Nick Shaw

Simultaneous quantitative analysis of eight vitamin D analogues in milk using liquid chromatography–tandem mass spectrometry

Publisher: Elsevier BV

Date: 09-2015

DOI: 10.1016/J.ACA.2015.08.017

Abstract: Milk is an important source of nutrients for various risk populations, including infants. The accurate measurement of vitamin D in milk is necessary to provide adequate supplementation advice for risk groups and to monitor regulatory compliance. Currently used liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods are capable of measuring only four analogues of vitamin D in unfortified milk. We report here an accurate quantitative analytical method for eight analogues of vitamin D: Vitamin D2 and D3 (D2 and D3), 25-hydroxy D2 and D3, 24,25-dihydroxy D2 and D3, and 1,25-dihydroxyD2 and D3. In this study, we compared saponification and protein precipitation for the extraction of vitamin D from milk and found the latter to be more effective. We also optimised the pre-column derivatisation using 4-phenyl-l,2,4-triazoline-3,5-dione (PTAD), to achieve the highest sensitivity and accuracy for all major vitamin D forms in milk. Chromatography was optimised to reduce matrix effects such as ion-suppression, and the matrix effects were eliminated using co-eluting stable isotope labelled internal standards for the calibration of each analogue. The analogues, 25-hydroxyD3 (25(OH)D3) and its epimer (3-epi-25(OH)D3) were chromatographically resolved, to prevent over-estimation of 25(OH)D3. The method was validated and subsequently applied for the measurement of total vitamin D levels in human, cow, mare, goat and sheep milk s les. The detection limits, repeatability standard deviations, and recovery ranges were from 0.2 to 0.4 femtomols, 6.30-13.5%, and 88.2-105%, respectively.

Factorial design-assisted supercritical carbon-dioxide extraction of cytotoxic active principles from Carica papaya leaf juice

Publisher: Springer Science and Business Media LLC

Date: 08-02-2019

DOI: 10.1038/S41598-018-37171-9

Abstract: The aims of this study are to investigate the selective cytotoxic activity of supercritical carbon dioxide (scCO 2 )-extracted freeze-dried leaf juice (FDLJ) of Carica papaya on squamous cell carcinoma (SCC25) cells, and to delineate the best small scale extraction parameters allowing maximal extract activity. Using scCO 2 as a solvent, six operating parameters were studied and the supercritical fluid extraction (SFE) process investigated using a factorial design 2 6-2 . The processing values promoting cytotoxic activity towards SCC-25 are: high pressure (250 bar), low temperature (35 °C), extended processing time (180 minutes), as well as a large amount of starting material (5 g). The factorial experimental design successfully identified the key parameters controlling the SFE of molecules cytotoxic to SCC cells from C. papaya juice. This study also validated the extraction method and showed that the SFE yield was reproducible. The chromatographic and mass spectrometric profiles of the scCO 2 extract acquired with high-resolution quadrupole time-of-flight mass spectrometry (LC-QToF-MS) were used to tentatively identify the bioactive compounds using comparative analysis. The principal compounds were likely to be mainly vitamins and phytosterols, some of which are documented to be cytotoxic to cancer cells.

Effect of perioperative opioids on cancer-relevant circulating parameters: mu opioid receptor and TLR4 activation potential, and proteolytic profile

Publisher: American Association for Cancer Research (AACR)

Date: 14-05-2018

DOI: 10.1158/1078-0432.CCR-18-0172

Abstract: Purpose: The purpose of this study is to investigate the potential interplay between opioid analgesia and tumor metastasis through modulation of μ-opioid receptor (MOR), Toll-like receptor 4 (TLR4) activation, and matrix degradation potential. Experimental Design: Plasma s les were collected from 60 patients undergoing elective lower limb joint replacement preoperatively and at 3, 6, and 24 hours after surgery pain scores were documented at the same time points. Opioid administration was recorded and converted into morphine IV equivalents. Plasma s les were also collected from 10 healthy volunteers. Alphascreen cyclic AMP assay and MOR-overexpressing cells were employed to quantify MOR activation. HEK-Blue hTLR4 were utilized to measure TLR4 activation. Circulating matrix metalloprotease and tissue inhibitor of matrix protease activities were assessed by gelatin zymography and reverse zymography, respectively. Results: Postoperative plasma s les displayed the ability to activate MOR and to inhibit lipopolysaccharide (LPS)-induced TLR4 activation. Linear mixed model analysis revealed that MOR activation had a significant effect on inhibition of LPS-induced TLR4 activation. Furthermore, TLR4 had a significant effect to explain pain scores. Postoperative s les also displayed altered circulating matrix-degrading enzymes activity potential, but this was correlated neither to opioid administration nor to MOR activation potential. Conclusions: Our results show for the first time that (i) opioids administered to surgery patients result in modulation of ligand-induced TLR4 activation and (ii) postoperative pain is associated with increased circulating TLR4 activation potential. Our study further promotes the use of MOR activation potential rather than opioid intake in clinical studies measuring opioid exposure at a given time point. Clin Cancer Res 24(10) 2319–27. ©2018 AACR.

Gastric metronidazole transfer in a new model of Helicobacter pylori gastritis

Publisher: Elsevier BV

Date: 04-2000

DOI: 10.1016/S0016-5085(00)81080-X

The pharmacokinetics and physiological effects of buprenorphine infusion in premature neonates.

Publisher: Wiley

Date: 09-1993

DOI: 10.1111/J.1365-2125.1993.TB04220.X

Abstract: 1. The pharmacokinetics and physiological effects of buprenorphine were studied in 12 newborn premature neonates (27 to 32 weeks gestational age) who were given a loading dose of 3.0 micrograms kg-1 of buprenorphine followed by an intravenous infusion of 0.72 micrograms kg-1 h-1 of buprenorphine. Plasma concentrations of buprenorphine were measured during the infusion, at steady-state and for 24 h after the cessation of the buprenorphine infusion. 2. The mean steady-state plasma buprenorphine concentration (+/- s.d.) for an infusion rate of 0.72 micrograms kg-1 h-1 was 4.3 +/- 2.6 ng ml-1. 3. Buprenorphine clearance was 0.23 +/- 0.07 l h-1 kg-1, the elimination half-life was 20 +/- 8 h and the volume of distribution was 6.2 +/- 2.11 l kg-1. 4. Small but significant falls were noted in systolic blood pressure at 6 h and heart rate at 1, 6 and 12 h after the administration of buprenorphine, but these did not appear to cause any clinical deterioration. 5. Four of the 12 subjects studied required an increase in the infusion rate of buprenorphine to achieve adequate sedation. 6. The results suggest that this dosing regimen of buprenorphine is safe but may not be as effective as other opioids in producing sedation and analgesia in premature newborns.

Chiral chromatography of amino acids on porous graphitic carbon coated with a series of N-substituted l-phenylalanine selectors effect of the anchor molecule on enantioselectivity

Publisher: Elsevier BV

Date: 03-1997

DOI: 10.1016/S0021-9673(96)00928-4

Molecular analysis of peroxisome proliferation in the hamster

Publisher: Elsevier BV

Date: 05-2004

DOI: 10.1016/J.TAAP.2004.01.019

Effects of salinity on antibiotic production in sponge-derived Salinispora actinobacteria

Publisher: Oxford University Press (OUP)

Date: 19-04-2014

DOI: 10.1111/JAM.12507

Abstract: To investigate the effects of growth conditions related to marine habitat on antibiotic production in sponge-derived Salinispora actinobacteria. Media with varying salt concentration were used to investigate the effects of salinity in relation to Salinispora growth and rifamycin production. The chemotypic profiles of the model strain Salinispora arenicola M413 was then assessed using metabolomic fingerprints from high-pressure liquid chromatography with diode array detection (HPLC-DAD) and multivariate data analysis, before extending this approach to two other strains of S. arenicola. Fingerprint data were generated from extracts of S. arenicola broth cultures grown in media of varying salt (NaCl) concentrations. These fingerprints were then compared using multivariate analysis methods such as principal components analysis (PCA) and orthogonal projection to latent structures discriminant analysis (OPLS-DA). From the analysis, a low-sodium growth condition (1% NaCl) was found to delay the onset of growth of the model S. arenicola M413 strain when compared to growth in media with either 3% artificial sea salt or 3% NaCl. However, low-sodium growth conditions also increased cell mass yield and contributed to at least a significant twofold increase in rifamycin yield when compared to growth in 3% artificial sea salt and 3% NaCl. The integration of HPLC-DAD and multivariate analysis proved to be an effective method of assessing chemotypic variations in Salinispora grown in different salt conditions, with clear differences between strain-related chemotypes apparent due to varying salt concentrations. The observed variation in S. arenicola chemotypic profiles further suggests ersity in secondary metabolites in this actinomycete in response to changes in the salinity of its environment.

Chromatographic retention behaviour of n-alkylbenzenes and pentylbenzene structural isomers on porous graphitic carbon and octadecyl-bonded silica studied using molecular modelling and QSRR

Publisher: Elsevier BV

Date: 10-2010

DOI: 10.1016/J.CHROMA.2010.08.023

Abstract: The retention behaviour of a series of 15 n-alkylbenzenes and pentylbenzene structural isomers and benzene were investigated using porous graphitic carbon (PGC) and octadecyl-bonded silica (ODS) stationary phases. Shorter chain n-alkylbenzenes and benzene (n=0-6), and all the pentylbenzene isomers were more strongly retained on ODS, although the selectivity was greater with PGC. For the pentylbenzene analytes the degree of branching in the alkyl chain at the position adjacent to the aromatic ring affects retention on PGC, with higher retention in less branched molecules. Molecular modelling studies have provided new insights into the geometry of aromatic π-π stacking interactions in retention on PGC. For alkylbenzenes with high branching at the position adjacent to the ring, the preferred geometry of association with the surface is with the branched chain directed away from the surface, a geometry not seen in the other alkylbenzenes. The most energetically favoured orientation for interaction between analytes and the PGC surface was found to be cofacial for toluene and ethylbenzene, whereas for other analytes this interaction was in a face-edge orientation. The alternative geometry of association observed with both toluene and ethylbenzene may explain the enhanced retention of these two analytes on PGC compared with their longer chain analogues. Quantitative structure-retention relationships revealed the importance of compactness in analyte structure during retention on PGC, with decreased compactness (associated with longer chain length and reduced chain branching) improving retention.

Ion-pair high-performance liquid chromatographic assay method for the assessment of clarithromycin stability in aqueous solution and in gastric juice

Publisher: Elsevier BV

Date: 06-1996

DOI: 10.1016/0378-4347(96)00064-3

Abstract: A simple and selective ion-pair HPLC method has been developed for the analysis of clarithromycin in aqueous solutions and in gastric juice. A Hypersil ODS 5-microns (150 x 4.6 mm I.D.) column was used with a mobile phase consisting of acetonitrile-aqueous 0.05 M phosphate buffer (pH 4.6) containing 5 mM l-octanesulphonic acid (50:50, v/v). The column temperature was 50 degrees C and detection was by UV absorption (210 nm). The limits of detection of 50-microliters s les were 0.4 microgram/ml (aqueous) and 0.78 microgram/ml (0.5 ml gastric juice) or better. The assay was linear in the range of 1.56 to 100 micrograms/ml with r2 values greater than 0.99. The recovery from the gastric juice s les was 98.5 +/- 2.9%. The method was applied successfully to determine the stability of clarithromycin in 0.01 M HCl and gastric juice.

Synergistic activity of tenofovir and nevirapine combinations released from polycaprolactone matrices for potential enhanced prevention of HIV infection through the vaginal route

Publisher: Elsevier BV

Date: 10-2014

DOI: 10.1016/J.EJPB.2014.05.018

Abstract: Polycaprolactone (PCL) matrices were simultaneously loaded with the antiviral agents, tenofovir (TFV) and nevirapine (NVP), in combination to provide synergistic activity in the prevention of HIV transmission through the vaginal route. TFV and NVP were incorporated in PCL matrices at theoretical loadings of 10%TFV-10% NVP, 5%TFV-5%NVP and 5%TFV-10%NVP, measured with respect to the PCL content of the matrices. Actual TFV loadings ranged from 2.1% to 4.2% equating to loading efficiencies of about 41-42%. The actual loadings of NVP were around half those of TFV (1.2-1.9%), resulting in loading efficiencies ranging from 17.2% to 23.5%. Approximately 80% of the initial content of TFV was released from the PCL matrices into simulated vaginal fluid (SVF) over a period of 30 days, which was almost double the cumulative release of NVP (40-45%). The release kinetics of both antivirals over 30 days were found to be described most satisfactorily by the Higuchi model. In vitro assay of release media containing combinations of TFV and NVP released from PCL matrices confirmed a potential synergistic/additive effect of the released antivirals on HIV-1 infection of HeLa cells. These findings indicate that PCL matrices loaded with combinations of TFV and NVP provide an effective strategy for the sustained vaginal delivery of antivirals with synergistic/additive activity.

A Simple and Sensitive LC-MS/MS Method for the Simultaneous Determination of Cyclophosphamide and Doxorubicin Concentrations in Human Plasma

Publisher: Bentham Science Publishers Ltd.

Date: 11-12-2017

DOI: 10.2174/1573412913666170321111815

Mango Extracts and the Mango Component Mangiferin Promote Endothelial Cell Migration

Publisher: American Chemical Society (ACS)

Date: 29-03-2010

DOI: 10.1021/JF100249S

Abstract: This study tested the hypothesis that mango extracts contain bioactive molecules capable of modulating endothelial cell migration, an essential step in the formation of new blood vessels or angiogenesis. The formation of new blood vessels is an important therapeutic target for diseases such as limb ischemia, coronary infarction or stroke. We examined the effect of mango peel and flesh extracts as well as the in idual polyphenolic molecules, mangiferin and quercetin, on bovine aortic cell migration using a modified Boyden chamber assay. Our results show that mangiferin, and extracts rich in mangiferin, increase endothelial cell migration. The dose-effect relationship for various extracts further suggests that this action of mangiferin is modulated by other components present in the extracts. The promigratory effect of mango extracts or mangiferin was unrelated to an effect on cell proliferation, and did not involve a change in the production of matrix metalloprotease-2 or -9 by the endothelial cells. Taken together, these results suggest that mangiferin present in mango extracts may have health promoting effects in diseases related to the impaired formation of new blood vessels.

Kinetics of drug metabolism inhibition: Use of metabolite concentration-time profiles

Publisher: Springer Science and Business Media LLC

Date: 10-1987

DOI: 10.1007/BF01061759

Abstract: Subarachnoid hemorrhage (SAH) is the subtype of stroke with one of the highest mortality rates and the least well-understood pathophysiologies. One of the very early events which may occur after SAH is a significant decrease of cerebral perfusion pressure (CPP) caused by the excessive increase of intracranial pressure during the initial bleeding. A severely decreased CPP results in global cerebral ischemia, an event also occurring after cardiac arrest. The aim of the current paper is to review the pathophysiological events occurring in experimental models of SAH and global cerebral ischemia and to evaluate the contribution and the importance of global cerebral ischemia for the pathophysiology of SAH.

Effect of pregnenolone carbonitrile, promethazine and antipyrine pretreatment on antipyrine metabolite formation in rats

Publisher: Informa UK Limited

Date: 1986

DOI: 10.3109/00498258609038988

Abstract: The effect of three inducers of cytochrome P-450-mediated drug oxidations (Pregnenolone carbonitrile, promethazine and antipyrine) on antipyrine metabolite kinetics has been investigated using the urinary metabolite pattern and 14CO2 exhalation rate (CER)-time profile following [N-methyl-14C]antipyrine administration. The CER-time profiles showed the characteristic changes associated with induction, namely, increased maximum CER and decreased half-life, previously observed in phenobarbitone and beta-naphthaflavone-induced rats. Calculation of formation rate constants based on urinary recovery of 3-hydroxymethyl-, 4-hydroxy- and nor-antipyrine indicated no clear selectivity of induction by any pretreatment. However, the percentage increase of the latter two metabolites was two- to four-fold greater than for the former metabolite. The use of the metabolite ratio (3-hydroxymethylantipyrine/norantipyrine) is proposed to assess the qualitative nature of induction of antipyrine metabolism.

Compound Identification and In Vitro Cytotoxicity of the Supercritical Carbon Dioxide Extract of Papaya Freeze-Dried Leaf Juice

Publisher: MDPI AG

Date: 20-05-2020

DOI: 10.3390/PR8050610

Abstract: Carica papaya leaves are used as a remedy for the management of cancer. Freeze-dried C. papaya leaf juice was extracted using a supercritical fluid extraction system. Compound identification was carried out using analytical techniques including liquid chromatography coupled to high-resolution quadrupole time-of-flight mass spectrometry (LC–QToF-MS) and gas chromatography–mass spectrometry (GC–MS). The cytotoxic activities of the scCO2 extract and its chemical constituents were determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on squamous cell carcinoma (SCC25) and human keratinocyte (HaCaT) cell lines. The chemical constituents were quantified by QToF-MS. The supercritical carbon dioxide (scCO2) extract of papaya freeze-dried leaf juice showed cytotoxic activity against SCC25. Three phytosterols, namely, β-sitosterol, c esterol, and stigmasterol, together with α-tocopherol, were confirmed to be present in the scCO2 extract. Quantitative analysis showed that β-sitosterol was the major phytosterol present followed by α-tocopherol, c esterol, and stigmasterol. β-Sitosterol and c esterol were active against SCC25 (half maximal inhibitory concentration (IC50) ≈ 1 µM), while stigmasterol was less active (~33 µM) but was biologically more selective against SCC25. Interestingly, an equimolar mixture of phytosterols was not more effective (no synergistic effect was observed) but was more selective than the in idual compounds. The compounds identified are likely accountable for at least part of the cytotoxicity and selectivity effects of C. papaya.

Effects of acid treatment on the trace metal content of chromatographic silica: bulk analysis, surface analysis and chromatographic performance of bonded phases

Publisher: Elsevier BV

Date: 2001

DOI: 10.1016/S0021-9673(00)01000-1

Abstract: A series of studies has been carried out on the effect of refluxing silica chromatography particles for 0.5 h and 18 h in water, dilute hydrochloric acid and dilute hydrofluoric acid. The bulk and surface trace metal concentrations were measured by inductively-coupled plasma atomic emission spectroscopy, static secondary ion mass spectrometry (SSIMS) and X-ray photoelectron spectroscopy. Diffuse reflectance Fourier transform infrared spectroscopy was used to determine changes in 'isolated" and "bonded" silanol groups. The chromatographic behaviour of a series of weakly basic analytes was investigated on C8 and C18 bonded phases manufactured from the acid-treated silicas. The different reflux treatments all resulted in a reduction in the numbers of isolated silanols compared with the untreated silica and SSIMS analysis suggested that the HF-treated silicas had undergone a more efficient surface rehydroxylation. Bulk trace metals were removed most effectively by the HF treatment, with the multivalent elements (Ti and Al) being the most difficult to remove. Surface specific analysis suggested that trace metals were removed more rapidly from the surface of the silica compared to the bulk matrix and that the acid treatments resulted in halide contamination of the silica surface. Evidence is presented to suggest that the bulk metal content of the silica is not representative of the concentration of metals at the chromatographic surface. The chromatographic investigations showed that the HF-treated silica gave substantially better performance towards weak bases than the HCl-treated silicas.

Beta-Endorphin 1–31 Biotransformation and cAMP Modulation in Inflammation

Publisher: Public Library of Science (PLoS)

Date: 11-03-2014

DOI: 10.1371/JOURNAL.PONE.0090380

Mango fruit peel and flesh extracts affect adipogenesis in 3T3-L1 cells

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C2FO30073G

Abstract: Obesity is associated with many chronic disease states, such as diabetes mellitus, coronary disease and certain cancers, including those of the breast and colon. There is a growing body of evidence that links phytochemicals with the inhibition of adipogenesis and protection against obesity. Mangoes (Mangifera indica L.) are tropical fruits that are rich in a erse array of bioactive phytochemicals. In this study, methanol extracts of peel and flesh from three archetypal mango cultivars Irwin, Nam Doc Mai and Kensington Pride, were assessed for their effects on a 3T3-L1 pre-adipocyte cell line model of adipogenesis. High content imaging was used to assess: lipid droplets per cell, lipid droplet area per cell, lipid droplet integrated intensity, nuclei count and nuclear area per cell. Mango flesh extracts from the three cultivars did not inhibit adipogenesis peel extracts from both Irwin and Nam Doc Mai, however, did so with the Nam Doc Mai extract most potent at inhibiting adipogenesis. Peel extract from Kensington Pride promoted adipogenesis. The inhibition of adipogenesis by Irwin (100 μg mL(-1)) and Nam Doc Mai peel extracts (50 and 100 μg mL(-1)) was associated with an increase in the average nuclear area per cell similar effects were seen with resveratrol, suggesting that these extracts may act through pathways similar to resveratrol. These results suggest that differences in the phytochemical composition between mango cultivars may influence their effectiveness in inhibiting adipogenesis, and points to mango fruit peel as a potential source of nutraceuticals.

Determination of morphine and 6-acetylmorphine in plasma by high-performance liquid chromatography with fluorescence detection

Publisher: Elsevier BV

Date: 05-1991

DOI: 10.1016/0378-4347(91)80118-V

Abstract: A method is described for the simultaneous determination of morphine and 6-acetylmorphine in small volumes of human plasma by normal-phase high-performance liquid chromatography using solid-phase extraction, dansyl derivatisation and fluorescence detection. The lower limits of quantitation in a 0.1-ml plasma s le are 10 ng/ml for morphine and 25 ng/ml for 6-acetylmorphine. The method has been applied to determine concentrations of morphine and 6-acetylmorphine in plasma s les from premature babies administered an intravenous infusion of diamorphine.

Kynurenine aminotransferase activity in human liver: identity with human hepatic C-S lyase activity and a physiological role for this enzyme

Publisher: Elsevier BV

Date: 05-1992

DOI: 10.1016/0378-4274(92)90281-N

Abstract: The C-S lyase enzymes are responsible for the generation of mutagenic and cytotoxic metabolites via aberrant drug-metabolising pathways in mammalian tissues. We have examined human hepatic cytosolic, mitochondrial and microsomal fractions for evidence of C-S lyase activity. The cytosolic enzyme was purified using fast protein liquid chromatography over FFQ Sepharose, Mono P and Superose 12. An homogeneous protein (monitored by SDS-PAGE) was obtained following purification, and an 11-fold increase in C-S lyase specific activity was observed. The molecular weight of the enzyme was found to be 37 kDa in denaturing conditions, 82.3 kDa in non-denaturing conditions, and the C-S lyase activity was shown to co-purify with kynurenine aminotransferase activity when the transaminase activity of the enzyme was examined with kynurenine as the substrate.

Screening of rifamycin producing marine sponge bacteria by LC-MS-MS

Publisher: Elsevier BV

Date: 06-2007

DOI: 10.1016/J.JCHROMB.2007.01.042

Abstract: HPLC-MS-MS has been used for the identification and characterisation of rifamycin B and rifamycin SV in various strains of the marine sponge-derived bacterium Salinispora. Gradient elution using acetonitrile/water/ammonium acetate was used to separate the rifamycins from the matrix and negative ion-electrospray mass spectrometry was used for detection and confirmation. The presence of rifamycin in bacterial extracts was confirmed by matching retention times, parent ion spectra and the fragmentated parent ion spectra of the standard compounds and the bacterial extracts. All strains of the marine sponge bacterium Salinispora tested were found to contain rifamycin thus an alternate actinobacterial source of rifamycin was established.

Mango (Mangifera indica L.) peel extract fractions from different cultivars differentially affect lipid accumulation in 3T3-L1 adipocyte cells

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C2FO30224A

Abstract: Plant phytochemicals are increasingly recognised as sources of bioactive molecules which may have potential benefit in many health conditions. In mangoes, peel extracts from different cultivars exhibit varying effects on adipogenesis in the 3T3-L1 adipocyte cell line. In this study, the effects of preparative HPLC fractions of methanol peel extracts from Irwin, Nam Doc Mai and Kensington Pride mangoes were evaluated. Fraction 1 contained the most hydrophilic components while subsequent fractions contained increasingly more hydrophobic components. High content imaging was used to assess mango peel fraction effects on lipid accumulation, nuclei count and nuclear area in differentiating 3T3-L1 cells. For all three mango cultivars, the more hydrophilic peel fractions 1-3 inhibited lipid accumulation with greater potency than the more hydrophobic peel fractions 4. For all three cultivars, the more lipophilic fraction 4 had concentrations that enhanced lipid accumulation greater than fractions 1-3 as assessed by lipid droplet integrated intensity. The potency of this fraction 4 varied significantly between cultivars. Using mass spectrometry, five long chain free fatty acids were detected in fraction 4 these were not present in any other peel extract fractions. Total levels varied between cultivars, with Irwin fraction 4 containing the highest levels of these free fatty acids. Lipophilic components appear to be responsible for the lipid accumulation promoting effects of some mango extracts and are the likely cause of the erse effects of peel extracts from different mango cultivars on lipid accumulation.

Randomised, double blind trial of two loading dose regimens of diamorphine in ventilated newborn infants.

Publisher: BMJ

Date: 07-1995

DOI: 10.1136/FN.73.1.F22

Abstract: To compare the safety and efficacy of two loading doses of diamorphine in 27 ventilated newborn infants in a randomised double blind trial. Fifty or 200 mcg/kg were infused intravenously over 30 minutes, followed by a 15 mcg/kg/hour continuous infusion. Serial measurements were made of physiology, behaviour, and stress hormones. Both loading doses produced small but significant falls in blood pressure. The 200 mcg/kg dose produced greater respiratory depression, and two infants deteriorated clinically, requiring resuscitation. Loading reduced respiratory effort in most of the infants, but had little effect on behavioural activity. Stress hormone concentrations were reduced at six hours in both dosage groups differences between loading doses were not significant. Morphine, morphine-3-glucuronide, and morphine-6-glucuronide were detected in the plasma of all patients. No significant differences in concentrations between loading doses were found. Diamorphine reduces the stress response in ventilated newborn infants. A high loading dose confers no benefit, and may produce undesirable physiological effects. A 50 mcg/kg loading dose seems to be safe and effective.

Gastric amoxicillin transfer in Helicobacter pylori +VE patients: Effect of bile reflux

Publisher: Elsevier BV

Date: 04-2000

DOI: 10.1016/S0016-5085(00)81081-1

Simultaneous determination of 12 vitamin D compounds in human serum using online sample preparation and liquid chromatography-tandem mass spectrometry

Publisher: Elsevier BV

Date: 2018

DOI: 10.1016/J.CHROMA.2017.12.012

Abstract: The development and validation of a method to simultaneously quantify 12 vitamin D compounds in human serum by LC-MS/MS is described. The main challenge was that of extracting and chromatographing vitamin D compounds with a range of polarities, both lipophilic and hydrophilic, in a single analytical procedure. The extractions of all 12 vitamin D compounds were achieved by an optimised protein precipitation method using acetonitrile as the precipitant, and the separation was accomplished by using a pentafluorophenyl (PFP) column. The sensitivity was increased by minimising matrix effects in MS detector rather than using a lengthy derivatisation procedure an online solid phase extraction (SPE) using a PFP guard column was used for cleanup. Detection limits for all compounds were in the picomole range when using a 500μL s le volume. Recovery percentages ranged from 92% to 99%. LC-MS/MS resolution of all 12 vitamin D compounds, including the chromatographic separation of 25(OH)D

Antitumor Benzothiazoles. 7. Synthesis of 2-(4-Acylaminophenyl)benzothiazoles and Investigations into the Role of Acetylation in the Antitumor Activities of the Parent Amines

Publisher: American Chemical Society (ACS)

Date: 23-01-1999

DOI: 10.1021/JM981076X

Temporal effects on antipyrine metabolite kinetics in aroclor 1254-treated rats

Publisher: Elsevier BV

Date: 06-1986

DOI: 10.1016/0041-008X(86)90130-4

Abstract: The in vivo consequences of a single dose of Aroclor 1254 (50 mg/kg) on the drug metabolizing capacity of rats were investigated. A noninvasive method, employing [N-methyl-14C]-antipyrine where both 14CO2 exhalation and urinary excretion of 4-hydroxy-, 3-hydroxymethyl-, and norantipyrine were monitored, was used. A group of rats were sequentially tested over a 3-week period to characterize temporal patterns. The antipyrine metabolite kinetic approach demonstrated that induction of hepatic cytochrome P-450 is maximal 3-6 days after Aroclor 1254 administration and the effects were apparent for at least a further 14-17 days. Evidence is presented to suggest selective effects of Aroclor 1254 on different cytochromes P-450 are apparent in vivo.

Becoming a pharmacist: Students' perceptions of their curricular experience and professional identity formation

Publisher: Elsevier BV

Date: 05-2014

DOI: 10.1016/J.CPTL.2014.02.010

Enhancing the ratio of molecular ions to non-covalent compounds in the electrospray interface of LC-MS in quantitative analysis

Publisher: Springer Science and Business Media LLC

Date: 12-05-2005

DOI: 10.1007/S00216-005-3236-Y

Abstract: A common problem encountered during the development of MS methods for the quantitation of small organic molecules by LC-MS is the formation of non-covalently bound species or adducts in the electrospray interface. Often the population of the molecular ion is insignificant compared to those of all other forms of the analyte produced in the electrospray, making it difficult to obtain the sensitivity required for accurate quantitation. We have investigated the effects of the following variables: orifice potential, nebulizer gas flow, temperature, solvent composition and the s le pH on the relative distributions of ions of the types MH+, MNa+, MNH4+, and 2MNa+, where M represents a small organic molecule: BAY 11-7082 ((E)-3-[4-methylphenylsulfonyl]-2-propenenitrile). Orifice potential, solvent composition and the s le pH had the greatest influence on the relative distributions of these ions, making these parameters the most useful for optimizing methods for the quantitation of small molecules.

Cyclodextrin-crosslinked poly(acrylic acid): Synthesis, physicochemical characterization and controlled release of diflunisal and fluconazole from hydrogels

Publisher: Elsevier BV

Date: 02-2013

DOI: 10.1016/J.IJPHARM.2013.01.005

Abstract: The aim of this work was to develop mucoadhesive hydrogels with variable drug delivery properties by crosslinking poly(acrylic acid) (PAA) with cyclodextrins (CDs). CD-PAA polymers with high CD content and good inter-batch reproducibility were synthesized by activating PAA with SOCl2, then reacting PAA chloride with CD in the presence of 4-dimethylaminopyridine at 50°C. Manipulation of the synthesis conditions affected the physicochemical character of the CD-PAA polymers and hydrogels in terms of CD content, the average number of ester bonds to an in idual CD, viscosity, and the association and release of model drugs. Inclusion complexation of diflunisal (DIF) and fluconazole (FLZ) with CD-PAA hydrogels was assessed by (19)F NMR spectroscopy and association constants (Kas) for DIF were in the range 220-486M(-1) with βCD-PAA and 1327-6055M(-1) with hydroxypropyl-βCD-PAA. For FLZ the Ka range was 34-171M(-1) with hydroxypropyl-βCD-PAA. The hydrogels were found to release both drugs by means of Fickian diffusion as the predominant mechanism. A slight trend toward negative correlation was found between the Ka and Higuchi kH values for DIF. These results highlight the potential of CD-PAA hydrogels to control the release of model drugs through inclusion complexation.

Review of Procedures Used for the Extraction of Anti-Cancer Compounds from Tropical Plants

Publisher: Bentham Science Publishers Ltd.

Date: 03-2015

DOI: 10.2174/1871520614666141114202104

Abstract: Tropical plants are important sources of anti-cancer lead molecules. According to the US National Cancer Institute, out of the 3000 plants identified as active against cancer using in vitro studies, 70% are of tropical origin. The extraction of bioactive compounds from the plant materials is a fundamental step whose efficiency is critical for the success of drug discovery efforts. There has been no review published of the extraction procedures of anti-cancer compounds from tropical plants and hence the following is a critical evaluation of such procedures undertaken prior to the use of these compounds in cancer cell line studies, during the last five years. It presents a comprehensive analysis of all approaches taken to extract anti-cancer compounds from various tropical plants. (Databases searched were PubMed, SciFinder, Web of Knowledge, Scopus, Embase and Google Scholar).

The effect of omeprazole on the pharmacokinetics of metronidazole and hydroxymetronidazole in human plasma, saliva and gastric juice

Publisher: Wiley

Date: 09-1997

DOI: 10.1046/J.1365-2125.1997.T01-1-00572.X

Abstract: To evaluate the effect of omeprazole on the pharmacokinetics of metronidazole and hydroxymetronidazole in plasma, gastric juice and saliva following intravenous infusion or oral dosing of metronidazole. Eight volunteers received single doses of metronidazole (400 mg) intravenously and orally, whilst taking placebo or omeprazole (40 mg, twice daily for 5 days) in a randomized 4-way crossover study. Metronidazole and hydroxymetronidazole concentrations in plasma, saliva and gastric juice s les were determined by h.p.l.c. Pharmacokinetic parameters for metronidazole and hydroxymetronidazole were calculated, and the significance of the mean differences in parameters between omeprazole and placebo co-administration was assessed using a two-tailed, paired t-test. There were no significant differences (P < 0.05) in any of the plasma or saliva pharmacokinetic parameter values for metronidazole between volunteers receiving omeprazole or placebo when metronidazole was administered either as an intravenous infusion or orally. Following intravenous administration of metronidazole to the placebo group and omeprazole treated group respectively, the gastric transfer of metronidazole was significantly reduced from 15.5 +/- 10.4% to 2.6 +/- 1.0% of the dose (P = 0.007 95% CI of difference 4.8 to 21.0) with concomitant changes in the metronidazole AUC (from 77.5 +/- 18.0 mumol l-1 h to 352.6 +/- 182.1 mumol l-1 h P = 0.0003 95% CI of difference 127.6 to 422.7), Cmax (from 61.4 +/- 26.5 mumol l-1 to 271.8 +/- 104.3 mumol l-1 p = 0.0001 95% CI of difference 118.6 to 302.1). Similarly, the gastric juice AUC of hydroxymetronidazole was significantly reduced from 3.2 +/- 1.9 mumol l-1 h to 1.5 +/- 0.8 mumol l-1 h of the dose (P = 0.0043 95% CI of difference 0.4 to 3.0) with a concomitant change in Cmax (from 5.0 +/- 2.5 mumol l-1 to 3.0 +/- 1.2 mumol l-1 P = 0.0007 95% CI of difference 0.7 to 3.4). Omeprazole had little effect on the plasma and salivary pharmacokinetics of metronidazole (or its hydroxymetabolite) after intravenous or oral administration, but it did have a substantial effect on the pharmacokinetics of metronidazole and hydroxymetronidazole in gastric juice.

Collection and determination of nucleotide metabolites in neonatal and adult saliva by high performance liquid chromatography with tandem mass spectrometry

Publisher: Elsevier BV

Date: 07-2013

DOI: 10.1016/J.JCHROMB.2013.05.001

Abstract: Saliva contains a number of biochemical components which may be useful for diagnosis/monitoring of metabolic disorders, and as markers of cancer or heart disease. Saliva collection is attractive as a non-invasive s ling method for infants and elderly patients. We present a method suitable for saliva collection from neonates. We have applied this technique for the determination of salivary nucleotide metabolites. Saliva was collected from 10 healthy neonates using washed cotton swabs, and directly from 10 adults. Two methods for saliva extraction from oral swabs were evaluated. The analytes were then separated using high performance liquid chromatography (HPLC) with tandem mass spectrometry (MS/MS). The limits of detection for 14 purine yrimidine metabolites were variable, ranging from 0.01 to 1.0μM. Recovery of hydrophobic purine yrimidine metabolites from cotton tips was consistently high using water/acetonitrile extraction (92.7-111%) compared with water extraction alone. The concentrations of these metabolites were significantly higher in neonatal saliva than in adults. Preliminary ranges for nucleotide metabolites in neonatal and adult saliva are reported. Hypoxanthine and xanthine were grossly raised in neonates (49.3±25.4 30.9±19.5μM respectively) compared to adults (4.3±3.3 4.6±4.5μM) nucleosides were also markedly raised in neonates. This study focuses on three essential details: contamination of oral swabs during manufacturing and how to overcome this weighing swabs to accurately measure small saliva volumes and methods for extracting saliva metabolites of interest from cotton swabs. A method is described for determining nucleotide metabolites using HPLC with photodiode array or MS/MS. The advantages of utilising saliva are highlighted. Nucleotide metabolites were not simply in equilibrium with plasma, but may be actively secreted into saliva, and this process is more active in neonates than adults.

A rapid method for the simultaneous determination of the major metabolites of sulphasalazine in plasma

Publisher: Elsevier BV

Date: 1983

DOI: 10.1016/S0378-4347(00)84450-3

Abstract: Nonsteroidal anti-inflammatory drugs (NSAIDs) are used as tocolytics, which are medications that suppress uterine contractions for preterm birth prevention. Their effect on cerebral/systemic vascular beds poses the question of whether antenatal NSAID exposure is associated with neonatal hypertension. We performed a retrospective case-control study in a tertiary neonatal intensive care unit, including 40 hypertension cases (hospitalized neonates ≥ 35 weeks with systolic BP > 100 mm Hg on three consecutive days) compared to 134 controls matched by gestational age at delivery, plurality, and delivery date. Cases and controls were compared by antenatal NSAID exposure, other common tocolytics, and maternal/neonatal characteristics and complications. Multivariable logistic regression was used to estimate the odds of hypertension among those with prenatal exposure to NSAIDs versus those without exposure. Newborns with hypertension had a lower gestational age at delivery and increased incidence of neonatal complications, including respiratory distress syndrome, bronchopulmonary dysplasia, surfactant administration, longer duration of ventilation, and history of umbilical artery catheterization. Days of indomethacin exposure were positively associated with greater odds of neonatal hypertension (OR 1.17 [1.00 to 1.38], P = 0.055), even after adjustment for other factors associated with neonatal hypertension. Newborns with hypertension were less likely to have been exposed to calcium channel blockers as a tocolytic. The results of our study suggest an association between prenatal exposure to nonsteroidal anti-inflammatory drugs and neonatal hypertension. Furthermore, our data suggest that prenatal calcium channel blocker exposure may protect against the development of neonatal hypertension. Future multicenter studies are needed to understand the risks of tocolytics and subsequent consequences in preterm infants.

Evidence for a saponin biosynthesis pathway in the body wall of the commercially significant sea cucumber Holothuria scabra

Publisher: MDPI AG

Date: 07-11-2017

DOI: 10.3390/MD15110349

Developmental cycle and pharmaceutically relevant compounds of Salinispora actinobacteria isolated from Great Barrier Reef marine sponges

Publisher: Springer Science and Business Media LLC

Date: 19-10-2013

DOI: 10.1007/S00253-012-4479-0

Abstract: The developmental cycle of the obligate marine antibiotic producer actinobacterium Salinispora arenicola isolated from a Great Barrier Reef marine sponge was investigated in relation to mycelium and spore ultrastructure, synthesis of rifamycin antibiotic compounds, and expression of genes correlated with spore formation and with rifamycin precursor synthesis. The developmental cycle of S. arenicola M413 on solid agar medium was characterized by substrate mycelium growth, change of colony color, and spore formation spore formation occurred quite early in colony growth but development of black colonies occurred only at late stages, correlated with a change in spore maturity in relation to cell wall layers. Rifamycins were detected throughout the growth cycle, but changed in relative quantity at particular phases in the cycle, with a marked increase after 32 days. Expression of the spore ision gene ssgA and the rifK gene for 3-amino-5-hydroxybenzoate synthase responsible for rifamycin precursor synthesis was seen even at early stages of the growth cycle. ssgA expression significantly increased between days 26 and 31, but rifK expression effectively remained constant throughout the growth cycle, consistent with the early synthesis of rifamycin. Factors other than precursor synthesis may be responsible for an observed late increase in rifamycin production. A useful approach for measuring and exploring the regulation of antibiotic synthesis and gene expression in the marine natural product producer S. arenicola has been established.

Retention Behavior of Ionizable Isomers in Reversed-Phase Liquid Chromatography:  A Comparative Study of Porous Graphitic Carbon and Octadecyl Bonded Silica

Publisher: American Chemical Society (ACS)

Date: 02-1996

DOI: 10.1021/AC950794D

Abstract: The retention behaviors of 36 positional isomers of ionizable substituted benzene compounds have been compared on two different packing materials: porous graphitic carbon (PGC) and octadecyl bonded silica (ODS) using 35% aqueous acetonitrile as the mobile phase. The effect of the mobile phase pH on the solute retention was studied over a range of pH values from pH 2.0 to 7.0. The retention as a function of pH was modeled using equations based on solute ionization. With PGC, the theoretical equations fitted the observed retention data for each class of solute, indicating that the retention mechanism was uniform over the whole pH range. However, with ODS, only the acidic solutes showed agreement with the theoretical model for the amine-containing compounds, serious deviations from the theory were observed, suggesting that strongly acidic silanols gave added retention at low mobile phase pH. Overall, PGC demonstrated a higher selectivity toward positional isomers than ODS. This was attributed to the greater steric discriminating ability arising from the flat surface of the PGC compared with the more fluid nature of the ODS bonded phase.

Evaporative light-scattering detection coupled to microcolumn liquid chromatography for the analysis of underivatized amino acids: Sensitivity, linearity of response and comparisons with UV absorbance

Publisher: Wiley

Date: 2001

DOI: 10.1002/MCS.1037

Concept mapping to evaluate an undergraduate pharmacy curriculum

Publisher: Elsevier BV

Date: 04-2011

DOI: 10.5688/AJPE75355

Human hepatic CS lyase: Transamination reactions and significant differences between kynurenine aminotransferase and kynureninase

Publisher: Elsevier BV

Date: 10-1992

DOI: 10.1016/S0960-894X(00)80218-8

Major Australian tropical fruits biodiversity: Bioactive compounds and their bioactivities

Publisher: Wiley

Date: 07-12-2012

DOI: 10.1002/MNFR.201100441

Abstract: The plant kingdom harbours many erse bioactive molecules of pharmacological relevance. Temperate fruits and vegetables have been highly studied in this regard, but there have been fewer studies of fruits and vegetables from the tropics. As global consumers demand and are prepared to pay for new appealing and exotic foods, tropical fruits are now being more intensively investigated. Polyphenols and major classes of compounds like flavonoids or carotenoids are ubiquitously present in these fruits, as they are in the temperate ones, but particular classes of compounds are unique to tropical fruits and other plant parts. Bioactivity studies of compounds specific to tropical fruit plants may lead to new drug discoveries, while the synergistic action of the wide range of erse compounds contained in plant extracts underlies nutritional and health properties of tropical fruits and vegetables. The evidence for in vitro and animal bioactivities is a strong indicator of the pharmacological promise shown in tropical fruit plant bio ersity. In this review, we will discuss both the occurrence of potential bioactive compounds isolated and identified from a selection of tropical fruit plants of importance in Australia, as well as recent studies of bioactivity associated with such fruits and other fruit plant parts.

Global metabolite analysis of the land snail Theba pisana hemolymph during active and aestivated states

Publisher: Elsevier BV

Date: 09-2016

DOI: 10.1016/J.CBD.2016.05.004

Abstract: The state of metabolic dormancy has fascinated people for hundreds of years, leading to research exploring the identity of natural molecular components that may induce and maintain this state. Many animals lower their metabolism in response to high temperatures and/or arid conditions, a phenomenon called aestivation. The biological significance for this is clear by strongly suppressing metabolic rate to low levels, animals minimize their exposure to stressful conditions. Understanding blood or hemolymph metabolite changes that occur between active and aestivated animals can provide valuable insights relating to those molecular components that regulate hypometabolism in animals, and how they afford adaptation to their different environmental conditions. In this study, we have investigated the hemolymph metabolite composition from the land snail Theba pisana, a remarkably resilient mollusc that displays an annual aestivation period. Using LC-MS-based metabolomics analysis, we have identified those hemolymph metabolites that show significant changes in relative abundance between active and aestivated states. We show that certain metabolites, including some phospholipids [e.g. LysoPC(14:0)], and amino acids such as l-arginine and l-tyrosine, are present at high levels within aestivated snails. Further investigation of our T. pisana RNA-sequencing data elucidated the entire repertoire of phospholipid-synthesis genes in the snail digestive gland, as a precursor towards future comparative investigation between the genetic components of aestivating and non-aestivating species. In summary, we have identified a large number of metabolites that are elevated in the hemolymph of aestivating snails, supporting their role in protecting against heat or desiccation.

Effect of omeprazole on the distribution of antibiotics in gastric juice

Publisher: Elsevier BV

Date: 04-1995

DOI: 10.1016/0016-5085(95)23072-6

Discovering the recondite secondary metabolome spectrum of salinispora species: A study of inter-species diversity

Publisher: Public Library of Science (PLoS)

Date: 12-03-2014

DOI: 10.1371/JOURNAL.PONE.0091488

Cyclodextrin-crosslinked poly(acrylic acid): Adhesion and controlled release of diflunisal and fluconazole from solid dosage forms

Publisher: Springer Science and Business Media LLC

Date: 11-01-2013

DOI: 10.1208/S12249-012-9903-3

Standard addition with internal standardisation as an alternative to using stable isotope labelled internal standards to correct for matrix effects—Comparison and validation using liquid chromatograph

Publisher: Elsevier BV

Date: 06-2018

DOI: 10.1016/J.CHROMA.2018.04.026

Abstract: With mass spectrometric detection in liquid chromatography, co-eluting impurities affect the analyte response due to ion suppression/enhancement. Internal standard calibration method, using co-eluting stable isotope labelled analogue of each analyte as the internal standard, is the most appropriate technique available to correct for these matrix effects. However, this technique is not without drawbacks, proved to be expensive because separate internal standard for each analyte is required, and the labelled compounds are expensive or require synthesising. Traditionally, standard addition method has been used to overcome the matrix effects in atomic spectroscopy and was a well-established method. This paper proposes the same for mass spectrometric detection, and demonstrates that the results are comparable to those with the internal standard method using labelled analogues, for vitamin D assay. As conventional standard addition procedure does not address procedural errors, we propose the inclusion of an additional internal standard (not co-eluting). Recoveries determined on human serum s les show that the proposed method of standard addition yields more accurate results than the internal standardisation using stable isotope labelled analogues. The precision of the proposed method of standard addition is superior to the conventional standard addition method.

Chromatographic behaviour of positional isomers on porous graphitic carbon

Publisher: Elsevier BV

Date: 04-1995

DOI: 10.1016/0021-9673(94)00813-O

Interaction of Opioids with TLR4—Mechanisms and Ramifications

Publisher: MDPI AG

Date: 21-10-2021

DOI: 10.3390/CANCERS13215274

Abstract: The innate immune receptor toll-like receptor 4 (TLR4) is known as a sensor for the gram-negative bacterial cell wall component lipopolysaccharide (LPS). TLR4 activation leads to a strong pro-inflammatory response in macrophages however, it is also recognised to play a key role in cancer. Recent studies of the opioid receptor (OR)-independent actions of opioids have identified that TLR4 can respond to opioids. Opioids are reported to weakly activate TLR4, but to significantly inhibit LPS-induced TLR4 activation. The action of opioids at TLR4 is suggested to be non-stereoselective, this is because OR-inactive (+)-isomers of opioids have been shown to activate or to inhibit TLR4 signalling, although there is some controversy in the literature. While some opioids can bind to the lipopolysaccharide (LPS)-binding cleft of the Myeloid Differentiation factor 2 (MD-2) co-receptor, pharmacological characterisation of the inhibition of opioids on LPS activation of TLR4 indicates a noncompetitive mechanism. In addition to a direct interaction at the receptor, opioids affect NF-κB activation downstream of both TLR4 and opioid receptors and modulate TLR4 expression, leading to a range of in vivo outcomes. Here, we review the literature reporting the activity of opioids at TLR4, its proposed mechanism(s), and the complex functional consequences of this interaction.

Intestinal lymphatic transport of three retinoids in the rat after oral administration: Effect of lipophilicity and lipid vehicle

Publisher: Elsevier BV

Date: 03-1996

DOI: 10.1016/0378-5173(95)04265-2

Quantification of clarithromycin, its 14-hydroxy and decladinose metabolites in rat plasma, gastric juice and gastric tissue using high-performance liquid chromatography with electrochemical detection

Publisher: Elsevier BV

Date: 2003

DOI: 10.1016/S1570-0232(02)00765-1

Abstract: A rapid, selective and sensitive HPLC assay has been developed for the simultaneous analysis of clarithromycin, its 14-hydroxy-clarithromycin metabolite, and its decladinose acid degradation product, in small volumes of rat gastric juice aspirate, plasma and gastric tissue. S le were extracted with n-hexane/2-butanol (4:1) and the internal standard was roxithromycin. A Kromasil ODS 5 micrometer(75x4.6 mm I.D.) column was used with a mobile phase consisting of acetonitrile/aqueous phosphate buffer (pH 7, 0.086 M) (45:55 v/v). The column temperature was 30 degrees C and coulometric detection was used at 850 mV using a screen voltage of 600 mV. The analysis time was less than 8 min. The limits of quantitation for clarithromycin, 14-OH clarithromycin and decladinose clarithromycin were 0.15 microgram ml(-1) or lower in plasma (0.05 ml) 0.16 microgram ml(-1) or lower in gastric juice (0.2 ml) and 0.51 microgram g(-1) or lower for gastric tissue (0.25 g). The method was linear up to at least 20.3, 15.4 and 12.5 microgram ml(-1) for clarithromycin, 14-OH-clarithromycin and decladinose, respectively, in gastric juice aspirate and plasma and up to 40.6, 30.9 and 25.0 microgram g(-1) in gastric tissue. The assay was applied to the measurement of clarithromycin, 14-OH-clarithromycin and, for the first time, decladinose clarithromycin in pharmacokinetic studies of gastric transfer of clarithromycin in in idual rats.

Dynorphin A 1–17 biotransformation in inflamed tissue, serum and trypsin solution analysed by liquid chromatography–tandem mass spectrometry

Publisher: Springer Science and Business Media LLC

Date: 22-09-2012

DOI: 10.1007/S00216-012-6406-8

Abstract: Dynorphin A 1-17 (DYN A) is an endogenous neuropeptide that is of interest due to its erse roles in analgesia, inflammation and addiction. Upon release, DYN A is subject to metabolism by a range of enzymes and its biotransformation is dependent on the site and environment into which it is released. In this study, we investigated the biotransformation of DYN A in rat inflamed tissue at pH 7.4 and 5.5, in rat serum and in trypsin solution. DYN A-porcine was incubated at 37 °C in each matrix over a range of incubation periods. The resultant fragments were separated using a C4 column and detected by mass spectrometry using total ion current mode. Incubation of DYN A in trypsin solution and in rat serum resulted in 6 and 14 fragments, respectively. Incubation in inflamed rat paw tissue occasioned 21 fragments at pH 7.4 and 31 fragments at pH 5.5. Secondary breakdown of some larger primary fragments was also observed in this study.

Characterization of a range of alkyl‐bonded silica HPLC stationary phases: XPS and ToF‐SIMS studies

Publisher: Wiley

Date: 05-1994

DOI: 10.1002/SIA.740210502

Study of beta endorphin metabolism in inflamed tissue, serum and trypsin solution by liquid chromatography–tandem mass spectrometric analysis

Publisher: Springer Science and Business Media LLC

Date: 10-01-2012

DOI: 10.1007/S00216-011-5686-8

Abstract: Beta endorphin (β-END) is recognised as one of the most significant endogenous neuropeptides, responsible for a wide range of biological activities in the body. However, within the body β-END is exposed to hydrolysis by a variety of enzymes. In this study, we investigated the metabolism and fragmentation pattern of β-END in rat inflamed tissue, in rat serum and in trypsin solution. β-END (1-31)-rat was incubated at 37 °C in each matrix for different incubation times. The resultant fragments were separated using a C4 column and detected by mass spectrometry using total ion current mode. Structural information for the fragments was elucidated using tandem mass spectrometry. Incubation of β-END (1-31)-rat in trypsin solution and in rat serum resulted in 8 and 13 fragments, respectively. Incubation in inflamed rat paw tissue resulted in 22 fragments at pH 7.4 and 26 fragments at pH 5.5. Some of these fragments were common to both pH values. The degradation of β-END (1-31)-rat in inflamed tissue at pH 5.5 was faster than that at pH 7.4. Secondary fragmentation of some larger primary fragments was also observed in this study.

Resistance to Nonspecific Protein Adsorption by Poly(vinyl alcohol) Thin Films Adsorbed to a Poly(styrene) Support Matrix Studied Using Surface Plasmon Resonance

Publisher: American Chemical Society (ACS)

Date: 11-09-2001

DOI: 10.1021/AC010368U

Abstract: Thin films of poly(vinyl alcohol) (PVA) polymer were prepared on a flat, nonporous, poly(styrene) support matrix by adsorption from aqueous solution and were characterized in order to investigate the nonspecific adsorption of proteins to a chromatographically relevant surface. The integrity and surface coverage of the PVA thin films were established by surface analysis and atomic force microscopy imaging. The adsorption of the PVA polymers to the poly(styrene) substrate and the nonspecific adsorption of proteins to the PVA-coated surface were monitored using surface plasmon resonance. PVA was strongly bound to the poly(styrene) surface, but the surface density of the adsorbed PVA polymers was affected substantially by the concentration, molecular weight, and degree of hydrolysis of PVA polymers used. There was evidence of increasing degrees of unfolding of the PVA polymer onto the poly(styrene) surface as the concentration of the the PVA coating solution increased. Complete PVA coverage of the poly(styrene) surface was observed at PVA concentrations of 0.1 mg/mL or greater but with significant influence of both molecular weight and degree of hydrolysis of the PVA polymers. Resistance of the PVA-coated poly(styrene) surface to the nonspecific adsorption of human serum albumin (HSA) correlated with the degree of surface coverage of the PVA. The use of anti-HSA as a probe for adsorbed HSA suggested that HSA was displacing PVA from the poly(styrene) surface at the lower PVA surface coverage. A complete barrier to nonspecific protein adsorption was observed with a PVA coating solution concentration of greater than 0.1 mg/ mL with a degree of hydrolysis of <88%.

Electrophoretic behaviour of oligonucleotides and mono-, di- and triphosphate nucleotides by capillary zone electrophoresis

Publisher: Wiley

Date: 04-2001

DOI: 10.1002/1522-2683()22:6<1119::AID-ELPS1119>3.0.CO;2-X

Human renal C-S lyase: structure-activity relationships of cytosolic and mitochondrial enzymes

Publisher: Elsevier BV

Date: 09-1990

DOI: 10.1016/0378-4274(90)90142-9

Abstract: In 1981, the Ontario Ministry of Health began a lengthy and systematic process to build a modern and integrated Emergency Health Services System. This article outlines the Ministry's vision for emergency health services, the strategy used to realize this vision, and the accomplishments which have been achieved so far. Some of the concepts used successfully in this building process are also discussed, including the marketing of the systems approach, an emphasis on co-ordination and integration of efforts towards a well-defined common goal, and the involvement of an extensive network of health-care planners and providers in achieving consensus and co-operation. Finally, the article raises a number of major issues which must be addressed.

Systemic levels of glyceryl trinitrate following topical application to the anoderm do not correlate with the measured reduction in anal pressure

Publisher: Oxford University Press (OUP)

Date: 12-2001

DOI: 10.1046/J.0007-1323.2001.01932.X

Abstract: Topical 0·2 per cent glyceryl trinitrate (GTN) lowers resting anal pressure (RAP) and heals two-thirds of chronic anal fissures. Over 50 per cent of patients experience headache, presumably through systemic absorption, but the pharmacokinetics of GTN ointment are unknown. This study evaluated the systemic absorption profile of GTN, and correlation between plasma GTN levels, RAP, haemodynamic variables and side-effects. Thirty healthy volunteers were recruited with local medical school ethics committee approval. Continuous static anal manometry was performed for 10 min before and 2 h after application of 0·2 per cent GTN (0·5 g) to the anoderm. Blood s les were taken from an intravenous cannula, and pulse and blood pressure were measured before application of GTN, and 10, 20, 30, 40, 50, 60, 90, 120 and 180 min thereafter. Details of side-effects were recorded. GTN was detected in the plasma 10 min to 3 h after topical application. RAP was significantly reduced after 10 min, but had returned to pretreatment values by 120 min. Pulse was statistically unchanged during the study systolic blood pressure was significantly lower 20–90 min after GTN application, and diastolic pressure was decreased throughout the study. Headaches were experienced by 14 of 30 volunteers after a median (range) of 41 (4–120) min, persisting for 74 (30–176) min, with an intensity score of 19 (5–30) mm represented on a 100-mm linear visual analogue scale. There was no correlation between plasma GTN concentration, RAP, and the onset, duration or intensity of headaches. Topical GTN acts locally on the internal anal sphincter systemic levels do not contribute significantly to the reduction in RAP. There is marked interin idual variation in plasma GTN levels, and no correlation with haemodynamic variables and side-effects.

The C-S lysis of L-cysteine conjugates by aspartate and alanine aminotransferase enzymes

Publisher: SAGE Publications

Date: 05-1995

DOI: 10.1177/096032719501400506

Abstract: One biotransformation pathway which is responsible for the generation of mutagenic and cytotoxic metabolites is that of the C-S lysis (CSL) of L-cysteine conjugates. Thirteen cysteine S-conjugates, synthesised in our labora tories, were incubated with porcine heart aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT), and the C-S lyase activity for each enzyme-sub strate combination was determined. ASAT and ALAT were shown to exhibit CSL activity. It was also demonstrated that this activity was inhibited in the presence of the pyri doxal phosphate (PLP)-dependent enzyme inhibitor amino(oxyacetic acid) (AOAA) confirming the pyridoxal phosphate dependent mechanism by which C-S lysis is known to take place. Since the activities of these enzymes are used as biomarkers for the assessment of organ dam age, the potential interaction of L-cysteine conjugates with them may suppress their activity through direct inhibition.

Diversity of Mycobacterium species from marine sponges and their sensitivity to antagonism by sponge-derived rifamycin-synthesizing actinobacterium in the genus Salinispora

Publisher: Oxford University Press (OUP)

Date: 30-09-2010

DOI: 10.1111/J.1574-6968.2010.02118.X

Abstract: Eleven isolates of Mycobacterium species as well as an antimycobacterial Salinispora arenicola strain were cultured from the sponge Amphimedon queenslandica. The 16S rRNA, rpoB, and hsp65 genes from these Mycobacterium isolates were sequenced, and phylogenetic analysis of a concatenated alignment showed the formation of a large clade with Mycobacterium poriferae isolated previously from another sponge species. The separation of these Mycobacterium isolates into three species-level groups was evident from sequence similarity and phylogenetic analyses. In addition, an isolate that is phylogenetically related to Mycobacterium tuberculosis was recovered from the sponge Fascaplysinopsis sp. Several different mycobacteria thus appear to co-occur in the same sponge. An actinobacterium closely related to S. arenicola, a known producer of the antimycobacterial rifamycins, was coisolated from the same A. queenslandica specimen from which mycobacteria had been isolated. This Salinispora isolate was confirmed to synthesize rifamycin and displayed inhibitory effects against representatives from two of three Mycobacterium phylotype groups. Evidence for antagonism of sponge-derived Salinispora against sponge-derived Mycobacterium strains from the same sponge specimen and the production of antimycobacterial antibiotics by this Salinispora strain suggest that the synthesis of such antibiotics may have functions in competition between sponge microbial community members.

Measurement of amoxicillin in plasma and gastric samples using high-performance liquid chromatography with fluorimetric detection

Publisher: Elsevier BV

Date: 07-2002

DOI: 10.1016/S1570-0232(02)00179-4

Abstract: A rapid, selective and sensitive HPLC assay has been developed for the routine analysis of amoxicillin in rat plasma, gastric juice aspirate and gastric tissue which is applicable to low concentrations of amoxicillin (<1 microg mL(-1)) or small s le volumes. Amoxicillin was converted, via an internal rearrangement, to form a fluorescent product which was subsequently recovered using liquid-liquid extraction. A Kromasil ODS 3 microm (150 x 3.2 mm I.D.) column was maintained at 40 degrees C and used with a mobile phase consisting of methanol-water (55:45, v/v). Fluorimetric detection was at an lambda(ex) of 365 nm and an lambda(em) of 445 nm. The limits of quantitation for amoxicillin were 0.1 microg mL(-1) for gastric juice aspirate (500 microL), 0.5 microg mL(-1) for plasma (50 microL) and 0.075 microg g(-1) for gastric tissue (250 mg). The method was linear up to at least 15 microg mL(-1) in gastric juice aspirate, up to 200 microg mL(-1) in plasma and up to 100 microg g(-1) in gastric tissue, with inter- and intra-day RSDs being less than 19%. The assay has been applied to the measurement of amoxicillin in rat plasma, gastric juice aspirate and gastric tissue for pharmacokinetic studies in in idual rats.

Metal chelation, radical scavenging and inhibition of Aβ42 fibrillation by food constituents in relation to Alzheimer’s disease

Publisher: Elsevier BV

Date: 05-2016

DOI: 10.1016/J.FOODCHEM.2015.11.118

Abstract: Various food constituents have been proposed as disease-modifying agents for Alzheimer's disease (AD), due to epidemiological evidence of their beneficial effects, and for their ability to ameliorate factors linked to AD pathogenesis, namely by: chelating iron, copper and zinc scavenging reactive oxygen species and suppressing the fibrillation of amyloid-beta peptide (Aβ). In this study, nine different food constituents (l-ascorbic acid, caffeic acid, caffeine, curcumin, (-)-epigallocatechin gallate (EGCG), gallic acid, propyl gallate, resveratrol, and α-tocopherol) were investigated for their effects on the above factors, using metal chelation assays, antioxidant assays, and assays of Aβ42 fibrillation. An assay method was developed using 5-Br-PAPS to examine the complexation of Zn(II) and Cu(II). EGCG, gallic acid, and curcumin were identified as a multifunctional compounds, however their poor brain uptake might limit their therapeutic effects. The antioxidants l-ascorbic acid and α-tocopherol, with better brain uptake, deserve further investigation for specifically addressing oxidative stress within the AD brain.

Separation of pharmaceutical bases from neutral and acidic components by capillary electrochromatography

Publisher: Royal Society of Chemistry (RSC)

Date: 1998

DOI: 10.1039/A803876G

Bioactivity of Mango Flesh and Peel Extracts on Peroxisome Proliferator-Activated Receptor gamma [PPAR gamma] Activation and MCF-7 Cell Proliferation: Fraction and Fruit Variability

Publisher: Wiley

Date: 18-11-2011

DOI: 10.1111/J.1750-3841.2010.01899.X

Abstract: Mangos are a source of bioactive compounds with potential health promoting activity. Biological activities associated with mango fractions were assessed in cell-based assays to develop effective extraction and fractionation methodologies and to define sources of variability. Two techniques were developed for extraction and fractionation of mango fruit peel and flesh. Liquid chromatography-mass spectrometry (LC-MS) was used to assess compositional differences between mango fractions in flesh extracts. Many of the extracts were effective in inhibiting the proliferation of human breast cancer cells in vitro. All fractions showed bioactivity in PPAR activation assays, but quantitative responses showed marked fruit-to-fruit variability, highlighting the need to bulk fruit prior to extraction for activity-guided fractionation of bioactive components. This study also suggests that combinations of erse molecular components may be responsible for cell-level bioactivities from mango fractions, and that purification and activity profiling of in idual components may be difficult to relate to whole fruit effects. Practical Application: Although the health benefits of fruits are strongly indicated from studies of diet and disease, it is not known what role in idual fruit types can play, particularly for tropical fruits. This study shows that there is a ersity of potentially beneficial bioactivities within the flesh and peel of mango fruit, although fruit-to-fruit variation can be large. The results add to the evidence that the food approach of eating all components of fruits is likely to be more beneficial to health than consuming refined extracts, as the purification process would inevitably remove components with beneficial bioactivities.

Quantitative measurement of sulforaphane, iberin and their mercapturic acid pathway metabolites in human plasma and urine using liquid chromatography–tandem electrospray ionisation mass spectrometry

Publisher: Elsevier BV

Date: 12-2006

DOI: 10.1016/J.JCHROMB.2006.07.007

Abstract: A quantitative liquid chromatography positive ion electrospray tandem mass spectrometric method for the simultaneous determination of sulforaphane, iberin and their metabolites in human urine and plasma is described. The stability of the metabolites was determined in aqueous solution and in human plasma. Gradient liquid chromatographic separation was performed on a Zorbax SB-Aq 3.5 microm (100 x 2.1mm) column, using a mobile phase (flow rate 0.25 mL/min) consisting of ammonium acetate buffer at pH 4 and acetonitrile. Butyl thiocarbamoyl l-cysteine was used as internal standard. The assay was linear (r(2)>0.99) over the range of 0.03-300 microM in urine and 0.03-15 microM in plasma with intra- and inter-day assay precision (<10% CV) and accuracy (<20%). The lower limits of quantitation were in the range of 10-150 nmol/L. The method has been used to report, for the first time, in idual quantitative measurement of each of the mercapturic acid pathway metabolites of sulforaphane and iberin in both human plasma and urine following a dietary study of broccoli consumption.

The pharmacokinetics of trilostane and ketotrilostane in an interconverting system in the rat

Publisher: Springer Science and Business Media LLC

Date: 1992

DOI: 10.1023/A:1015828027060

Abstract: The pharmacokinetics of trilostane and one of its metabolites ketotrilostane are described and characterized in the rat following the separate intravenous administration of trilostane and ketotrilostane. It was noted during these studies that the parent compound and its metabolite undergo metabolic interconversion-trilostane producing ketotrilostane and ketotrilostane generating trilostane. This result means that trilostane is conserved in the body by interconversion--being metabolized to ketotrilostane and then subsequently back to the "parent" drug, trilostane.

Of Medicinal Chemistry, Pharmaceutical Sciences, and Pharmaceutical Science Communications

Publisher: Oxford University Press (OUP)

Date: 02-1996

DOI: 10.1111/J.2042-7158.1996.TB07110.X

Evaluation of Polycaprolactone Matrices for Sustained Vaginal Delivery of Nevirapine in the Prevention of Heterosexual HIV Transmission

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1002/JPS.24030

LC-MS-Based Metabolomics Study of Marine Bacterial Secondary Metabolite and Antibiotic Production in Salinispora arenicola

Publisher: MDPI AG

Date: 07-01-2015

DOI: 10.3390/MD13010249

Protein interactions with model chromatographic stationary phases constructed using self-assembled monolayers

Publisher: Wiley

Date: 03-2005

DOI: 10.1002/JSSC.200301667

Abstract: Model surfaces representative of chromatographic stationary phases were developed by immobilising an homologous series (C2-C18) of n-alkylthiols, mixed monolayers of C4/C18 and thioalkanes with alcohol, carboxylic acid, amino and sulphonic acid terminal groups onto a flat, silver-coated glass surface using self-assembled monolayer (SAM) chemistry. The processes of adsorption and desorption of serum albumins onto the monolayer surfaces was monitored in real-time using surface plasmon resonance (SPR). Alkyl-terminated SAMs all showed a strong adsorption of bovine serum albumin which was largely independent of alkyl chain length, the ratio of mixed C4/C18 SAMs or the solution pH/ionic strength. The adsorption of human serum albumin to carboxylic and amine terminated SAMs was shown to be predominantly via non-electrostatic interactions (hydrophobic or hydrogen bonding). However, sulphonic acid terminated SAMs showed almost exclusively electrostatic interactions with human serum albumin. This preliminary work using self-assembled monolayer chemistry confirms the usefulness of well characterised SAMs surfaces for investigating protein adsorption and desorption onto/from model chromatography surfaces and gives some guidance for selecting appropriate functionalities to develop better surfaces for chromatography and electrophoresis.

A highly sensitive LC-MS/MS method for quantitative determination of 7 vitamin D metabolites in mouse brain tissue

Publisher: Cold Spring Harbor Laboratory

Date: 23-02-2022

DOI: 10.1101/2022.02.21.481384

Abstract: Despite its critical role in neurodevelopment and brain function, vitamin-D (vit-D) homeostasis, metabolism and kinetics within the central nervous system remain largely undetermined. Thus, it is of critical importance to establish an accurate, highly sensitive and reproducible method to quantitate vit-D in brain tissue. Here, we present a novel liquid chromatography tandem mass spectrometry (LC-MS/MS) method and for the first time, demonstrate detection of seven major vit-D metabolites in brain tissues of C57BL/6J wild-type mice, namely: 1,25(OH) 2 D 3 , 3-epi-1,25(OH) 2 D 3, 1,25(OH) 2 D 2 , 25(OH)D 3 , 25(OH)D 2 , 24,25(OH) 2 D 3 , and 24,25(OH) 2 D 2 . Chromatographic separation was achieved on a pentaflurophenyol column 3 mM ammonium formate with water/methanol [A] and methanol/isopropanol [B] phases. Detection was by positive-ion electrospray tandem mass spectrometry. We used calibration standards of each metabolite prepared in brain matrices to validate the detection range, precision, accuracy and recovery. Isotopically labelled analogues, 1,25(OH) 2 D 3 -d 3 , 25(OH)D 3 -C 5 and 24,25(OH) 2 D 3 -d 6 , served as the internal standards for the closest molecular related metabolite in all measurements. The calibration range was between 1 fg/mL to 10 ng/mL with an LLOD and LLOQ of 10 fg/mL and 3 fg/mL, respectively. The intra-/inter-day precision and accuracy for measuring brain vit-D metabolites ranged between 0.12-11.53% and 0.28-9.11%, respectively. Recovery ranged between 99.06% and 106.9% for all metabolites. Collectively, the sensitivity and efficiency of our method supersedes previously reported protocols used to measure vit-D and to our knowledge, the first protocol to reveal the abundance of 25(OH)D 2 , 1,25(OH)D 2 and 24,25(OH) 2 D 2 , in brain tissue of any species. This technique may be important in supporting the future advancement of pre-clinical research into the function of vit-D in neurophysiological, neuropsychiatric, and neurodegeneration.

Novel Sources of Mammalian C-S Lyase Activity

Publisher: Oxford University Press (OUP)

Date: 02-1996

DOI: 10.1111/J.2042-7158.1996.TB07114.X

Abstract: The C-S lysis of L-cysteine conjugates is one biotransformation pathway which is responsible for the generation of mutagenic and cytotoxic metabolic species. Thirteen cysteine S-conjugates were synthesized in our laboratories and incubated with aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) enzymes from porcine heart tissue. The C-S lyase (CSL) activity for each enzyme-substrate combination was determined. ASAT and ALAT were shown to exhibit CSL activity and it was also demonstrated that this activity was inhibited in the presence of the pyridoxal phosphate-dependent enzyme inhibitor amino(oxyacetic acid) confirming the pyridoxal phosphate-dependent mechanism by which C-S lysis is known to take place. This finding has potentially important implications for the risk assessment of compounds which produce L-cysteine conjugates during their biotransformation.

The analysis of pharmaceutical bases on a silica stationary phase by capillary electrochromatography using aqueous mobile phases

Publisher: Springer Science and Business Media LLC

Date: 02-2000

DOI: 10.1007/BF02490560

Bio-Guided Fractionation of Papaya Leaf Juice for Delineating the Components Responsible for the Selective Anti-proliferative Effects on Prostate Cancer Cells

Publisher: Frontiers Media SA

Date: 16-11-2018

DOI: 10.3389/FPHAR.2018.01319

Cysteine Conjugate Toxicity in a Human Cell Line: Correlation with C-S Lyase Activity in Human Hepatic Tissue

Publisher: SAGE Publications

Date: 07-1993

DOI: 10.1177/096032719301200412

Abstract: C-S lyase enzymes catalyse the generation of mutagenic and/or cytotoxic thiols from cysteine conjugated xenobiotics. These cysteine conjugates are produced subsequent to glutathione conjugations as a metabolic step in the mercapturic acid pathway, traditionally thought of as a pathway solely associated with detoxification. Human Chang liver (HCL) cells were challenged with a range of cysteine conjugates demonstrated to be substrates for human hepatic C-S lyases. The cellular toxicity of these compounds was determined and it was observed that the rank order of substrate toxicity obtained for the HCL cells followed the rank order of C-S lyase activity of the substrates in a freshly isolated mitochondrial fraction of human tissue. The presence of C-S lyase activity was also established in this cell line.

Retention behaviour of an homologous series of oligodeoxythymidilic acids using reversed-phase ion-pair chromatography

Publisher: Springer Science and Business Media LLC

Date: 03-2002

DOI: 10.1007/BF02491658

High-performance liquid chromatographic analysis of trilostane and ketotrilostane in rat plasma

Publisher: Elsevier BV

Date: 06-1991

DOI: 10.1016/0378-4347(91)80333-8

Abstract: A simple high-performance liquid chromatographic (HPLC) method for assaying trilostane, a synthetic steroid, and one of its metabolites, ketotrilostane, in small volumes of rat plasma has been developed. A single liquid-liquid extraction was used to isolate the two compounds from acidified plasma prior to the quantitative analysis. The HPLC conditions involved the use of a Spherisorb ODS column (250 mm x 4.6 mm I.D.) and a mobile phase of 1,4-dioxan-Sorenson's buffer at pH 5.0 (52:48, v/v). Ethisterone was used as an internal standard. Trilostane and ketotrilostane were detected by their ultraviolet absorbance at 255 nm. Recoveries greater than 80% and detection limits of 50 ng/ml were obtained for both compounds. Inter-day coefficients of variation were less than 10%.

Role of alkyl and aryl substituents in chiral ligand exchange chromatography of amino acids study using porous graphitic carbon coated with N-substituted-l-proline selectors

Publisher: Elsevier BV

Date: 10-1997

DOI: 10.1016/S0021-9673(97)00601-8

Simultaneous quantitative analysis of nine vitamin D compounds in human blood using LC–MS/MS

Publisher: Future Science Ltd

Date: 03-2016

DOI: 10.4155/BIO.15.260

Abstract: Aim: It has been suggested that each member of the family of vitamin D compounds may have different function(s). Therefore, selective quantification of each compound is important in clinical research. Materials & methods: Development and validation attempts of a simultaneous determination method of 12 vitamin D compounds in human blood using precolumn derivatization followed by LC–MS/MS is described. Internal standard calibration with 12 stable isotope labeled analogs was used to correct for matrix effects in MS detector. Results & conclusion: Nine vitamin D compounds were quantifiable in blood s les with detection limits within femtomole levels. Serum (compared with plasma) was found to be a more suitable s le type, and protein precipitation (compared with saponification) a more effective extraction method for vitamin D assay.

The effect of pasteurization on trace elements in donor breast milk

Publisher: Springer Science and Business Media LLC

Date: 02-06-2016

DOI: 10.1038/JP.2016.88

Abstract: Premature infants often receive pasteurized donor human milk when mothers are unable to provide their own milk. This study aims to establish the effect of the pasteurization process on a range of trace elements in donor milk. Breast milk was collected from 16 mothers donating to the milk bank at the Royal Brisbane and Women's Hospital. S les were ided into pre- and post-pasteurization aliquots and were Holder pasteurized. Inductively coupled plasma mass spectrometry was used to analyze the trace elements zinc (Zn), copper (Cu), selenium (Se), manganese (Mn), iodine (I), iron (Fe), molybdenum (Mo) and bromine (Br). Differences in trace elements pre- and post-pasteurization were analyzed. No significant differences were found between the trace elements tested pre- and post-pasteurization, except for Fe (P<0.05). The median (interquartile range, 25 to 75% μg l(-1)) of trace elements for pre- and post- pasteurization aliquots were-Zn: 1639 (888-4508), 1743 (878-4143), Cu: 360 (258-571), 367 (253-531), Se: 12.34 (11.73-17.60), 12.62 (11.94-16.64), Mn: (1.48 (1.01-1.75), 1.49 (1.11-1.75), I (153 (94-189), 158 (93-183), Fe (211 (171-277), 194 (153-253), Mo (1.46 (0.37-2.99), 1.42 (0.29-3.73) and Br (1066 (834-1443), 989 (902-1396). Pasteurization had minimal effect on several trace elements in donor breast milk but high levels of inter-donor variability of trace elements were observed. The observed decrease in the iron content of pasteurized donor milk is, however, unlikely to be clinically relevant.

Anticancer activity of Carica papaya: A review

Publisher: Wiley

Date: 05-12-2012

DOI: 10.1002/MNFR.201200388

Abstract: Carica papaya is widely cultivated in tropical and subtropical countries and is used as food as well as traditional medicine to treat a range of diseases. Increasing anecdotal reports of its effects in cancer treatment and prevention, with many successful cases, have warranted that these pharmacological properties be scientifically validated. A bibliographic search was conducted using the key words "papaya", "anticancer", and "antitumor" along with cross-referencing. No clinical or animal cancer studies were identified and only seven in vitro cell-culture-based studies were reported these indicate that C. papaya extracts may alter the growth of several types of cancer cell lines. However, many studies focused on specific compounds in papaya and reported bioactivity including anticancer effects. This review summarizes the results of extract-based or specific compound-based investigations and emphasizes the aspects that warrant future research to explore the bioactives in C. papaya for their anticancer activities.

A sensitive, high-throughput fluorescent method for the determination of lactoperoxidase activities in milk and comparison in human, bovine, goat and camel milk

Publisher: Elsevier BV

Date: 03-2021

DOI: 10.1016/J.FOODCHEM.2020.128090

Quantification of metronidazole in small-volume biological samples using narrow-bore high-performance liquid chromatography

Publisher: Elsevier BV

Date: 09-2001

DOI: 10.1016/S0378-4347(01)00334-6

Abstract: A rapid, selective and sensitive HPLC assay has been developed for the routine analysis of metronidazole in small volumes of rat plasma, gastric aspirate and gastric tissue. The extraction procedure involves liquid-liquid extraction and a protein precipitation step. A microbore Hypersil ODS 3 microm (150 x 2.1 mm I.D.) column was used with a mobile phase consisting of acetonitrile-aqueous 0.05 M potassium phosphate buffer (pH 7) containing 0.1% triethylamine (10:90). The column temperature was at 25 degrees C and the detection was by UV absorbance at 317 nm. The limit of detection was 0.015 microg ml(-1) for gastric juice aspirate and plasma and 0.010 microg g(-1) for gastric tissue (equivalent to 0.75 ng on-column). The method was linear up to a concentration of 200 microg ml(-1) for plasma and gastric juice aspirate and up to 40 microg g(-1) for tissue, with inter- and intra-day relative standard deviations less than 14%. The measured recovery was at least 78% in all s le matrices. The method proved robust and reliable when applied to the measurement of metronidazole in rat plasma, gastric juice aspirate and gastric tissue for pharmacokinetic studies in in idual rats.

A role for caveola‐forming proteins caveolin‐1 and CAVIN1 in the pro‐invasive response of glioblastoma to osmotic and hydrostatic pressure

Publisher: Wiley

Date: 17-02-2020

DOI: 10.1111/JCMM.15076

A gas chromatography–mass spectrometry method for the measurement of fatty acid ω and ω−1 hydroxylation kinetics by CYP4A1 using an artificial membrane system

Publisher: Elsevier BV

Date: 02-2004

DOI: 10.1016/J.AB.2003.10.046

Abstract: A gas chromatography-mass spectrometry assay method for the analysis of lauric, myristic, and palmitic acids and their omega and omega(-1) hydroxylated metabolites from in vitro incubations of cytochrome P450 CYP4A1, involving solid-phase extraction and trimethysilyl derivatization, was developed. The assay was linear, precise, and accurate over the range 0.5 to 50microM for all the analytes. It has the advantages of a more rapid analysis time, an improved sensitivity, and a wider range of analytes compared with other methods. An artificial membrane system was optimized for application to purified CYP4A1 enzyme by investigating the molar ratios of cytochrome b(5) and cytochrome P450 reductase present in the incubation mixture. Using this method, the kinetics of omega and omega(-1) oxidation of lauric, myristic, and palmitic acids by CYP4A enzymes were measured and compared in rat liver microsomes and an artificial membrane system.

Solvent and stationary phase selectivity in capillary electrochromatography method development: Comparison of C18, C8, and phenyl-bonded phases for the separation of a series of substituted barbiturat

Publisher: Wiley

Date: 1999

DOI: 10.1002/(SICI)1520-667X(1999)11:4<305::AID-MCS8>3.0.CO;2-G

The Simultaneous Analysis of Eight Essential Trace Elements in Human Milk by ICP-MS

Publisher: Springer Science and Business Media LLC

Date: 06-01-2016

DOI: 10.1007/S12161-015-0396-Z

Synthesis of cationic derivatives of Quil A and the preparation of cationic immune-stimulating complexes (ISCOMs)

Publisher: Elsevier BV

Date: 07-2009

DOI: 10.1016/J.IJPHARM.2009.04.011

Abstract: The aim of the study was to prepare cationic ISCOMs using cationic derivatives of the saponin Quil A. The polyamines ethylenediamine, spermidine and spermine were conjugated with the glucuronic acid moiety of Quil A. The aqueous solubility of the derivatives increased with decreasing pH, and the pK(a) values were between 6 and 7. The CMCs of the ionised derivatives were around 0.5-1.0 mg/mL. Using the method of hydration of freeze-dried monophase systems, the interaction of each of the Quil A derivatives with phosphatidylcholine and cholesterol, at a mass ratio of 4:4:2 and a pH of 3 and 7.4, was investigated. A few ISCOM-like structures were present in the systems prepared at pH 7.4, hence the ternary system of Quil A spermine derivative, phosphatidylcholine and cholesterol was further investigated at pH 7.4 using a variety of mass ratios. A relatively high number of cationic ISCOM-like structures were observed at the mass ratio of 6:2:2. These ISCOM-like structures were less homogeneous and more irregular in shape than ISCOMs prepared from unmodified Quil A. Colloidal particles with positive zeta potential were produced and may find application in the delivery of nucleic acids or anionic proteins.

A Stability Indicating HPLC Assay for Diamorphine in Aqueous Solution

Publisher: Informa UK Limited

Date: 10-1994

DOI: 10.1080/10826079408013988

Mango Fruit Extracts Differentially Affect Proliferation and Intracellular Calcium Signalling in MCF-7 Human Breast Cancer Cells

Publisher: Hindawi Limited

Date: 2015

DOI: 10.1155/2015/613268

Abstract: The assessment of human cancer cell proliferation is a common approach in identifying plant extracts that have potential bioactive effects. In this study, we tested the hypothesis that methanolic extracts of peel and flesh from three archetypal mango cultivars, Irwin (IW), Nam Doc Mai (NDM), and Kensington Pride (KP), differentially affect proliferation, extracellular signal-regulated kinase (ERK) activity, and intracellular calcium ( [ Ca 2 + ] I ) signalling in MCF-7 human breast cancer cells. Mango flesh extracts from all three cultivars did not inhibit cell growth, and of the peel extracts only NDM reduced MCF-7 cell proliferation. Mango cultivar peel and flesh extracts did not significantly change ERK phosphorylation compared to controls however, some reduced relative maximal peak [ Ca 2 + ] I after adenosine triphosphate stimulation, with NDM peel extract having the greatest effect among the treatments. Our results identify mango interfruit and intrafruit (peel and flesh) extract variability in antiproliferative effects and [ Ca 2 + ] I signalling in MCF-7 breast cancer cells and highlight that parts of the fruit (such as peel and flesh) and cultivar differences are important factors to consider when assessing potential chemopreventive bioactive compounds in plants extracts.

Peroxisome proliferator activated receptor α regulates a male-specific cytochrome P450 in mouse liver

Publisher: Elsevier BV

Date: 09-2004

DOI: 10.1016/J.ABB.2004.06.025

Effect of Helicobacter gastritis on gastric antibiotic transfer in man

Publisher: Elsevier BV

Date: 04-2001

DOI: 10.1016/S0016-5085(01)82923-1

Development of an HPLC-MS/MS method for the selective determination of paracetamol metabolites in mouse urine

Publisher: Elsevier BV

Date: 03-2008

DOI: 10.1016/J.AB.2007.11.011

Abstract: An HPLC-MS/MS method has been developed for the selective quantitative analysis of paracetamol and its two major metabolites. The use of tandem MS enabled the detection and quantitation of metabolites in small s le sizes with high sensitivity and selectivity. Isocratic elution using acetonitrile and water containing formic acid combined with electrospray-tandem MS enabled the separation and accurate quantitation of each analyte and the internal standard 3-acetamidophenol. The on-column limits of detection for paracetamol, paracetamol sulfate, and paracetamol glucuronide were 2.4, 1.2, and 1.2 pmol, respectively. The method was applied to quantitate paracetamol and its metabolites in mouse urine. It is highly specific, sensitive, and easily adaptable to measure these analytes in biological fluids of other animals.

Effect of ionization suppression by trace impurities in mobile phase water on the accuracy of quantification by high‐performance liquid chromatography/mass spectrometry

Publisher: Wiley

Date: 04-05-2010

DOI: 10.1002/RCM.4549

Abstract: The high-performance liquid chromatography (HPLC) column is capable of enrichment re-concentration of trace impurities in the mobile phase during the column equilibration, prior to s le injection and elution. These impurities elute during gradient elution and result in significant chromatographic peaks. Three types of purified water were tested for their impurity levels, and hence their performances as mobile phase, in HPLC followed by total ion current (TIC) mode of MS. Two types of HPLC-grade water produced 3-4 significant peaks in solvent blanks while LC/MS-grade water produced no peaks (although peaks were produced by LC/MS-grade water also after a few days of standing). None of the three waters produced peaks in HPLC followed by UV-Vis detection. These peaks, if co-eluted with analyte, are capable of suppressing or enhancing the analyte signal in a MS detector. As it is not common practice to run solvent blanks in TIC mode, when quantification is commonly carried out using single ion monitoring (SIM) or single or multiple reaction monitoring (SRM or MRM), the effect of co-eluting impurities on the analyte signal and hence on the accuracy of the results is often unknown to the analyst. Running solvent blanks in TIC mode, regardless of the MS mode used for quantification, is essential in order to detect this problem and to take subsequent precautions.

Kynurenine aminotransferase/human hepatic C-S lyase: preliminary structure-activity relationship studies

Publisher: Elsevier BV

Date: 10-1992

DOI: 10.1016/S0960-894X(00)80217-6

Chromatographic retention behaviour of monosubstituted benzene derivatives on porous graphitic carbon and octadecyl-bonded silica studied using molecular modelling and quantitative structure–retention

Publisher: Elsevier BV

Date: 03-2012

DOI: 10.1016/J.CHROMA.2011.12.090

Abstract: The retention behaviour of a series of 28 monosubstituted benzenes, representing a erse range of functional groups and substituent shape, were investigated using porous graphitic carbon (PGC) and octadecyl-bonded silica (ODS) stationary phases. For the majority of analytes retention on PGC was greater than on ODS, and in most cases this effect occurred at both pH 2.5 and 7.0. The main trends observed on PGC (in comparison with ODS) were: (i) similar or reduced retention of low polarity molecules such as the hydrocarbon and halogenated analytes (ii) increased retention of conjugated analytes with extended planarity (iii) increased retention of polar and charged species and (iv) substantial increases in retention for selected polar and negatively charged analytes, including some ionised and unionised acid analytes. Poor retention of positively charged analytes was observed on both stationary phases. Molecular modelling studies have explored the geometry of π-π stacking interactions in retention on PGC and have highlighted the strong retention of large conjugated analytes, with extended planar conformations, which can interact with the graphite surface with cofacial geometry. Quantitative structure-retention relationships showed the importance of hydrophobic (π) and electronic factors (e.g. mean polarisability and LUMO energy) in retention on PGC, whilst retention on ODS was correlated to hydrophobicity (logP and π).

Hydrophilic Interaction Liquid Chromatography-Tandem Mass Spectrometric Determination of Creatinine in Human Urine

Publisher: Informa UK Limited

Date: 03-03-2014

DOI: 10.1080/00032719.2013.848363

Biotransformation of beta-endorphin and possible therapeutic implications

Publisher: Frontiers Media SA

Date: 2014

DOI: 10.3389/FPHAR.2014.00018

Quantitative analysis of lignocaine and metabolites in equine urine and plasma by liquid chromatography–tandem mass spectrometry

Publisher: Elsevier BV

Date: 07-2010

DOI: 10.1016/J.JCHROMB.2010.05.042

Abstract: In this paper, a method for the sensitive and reproducible analysis of lignocaine and its four principal metabolites, monoethylxylidide (MEGX), glycylxylidide (GX), 3-hydroxylignocaine (3-HO-LIG), 4-hydroxylignocaine (4-HO-LIG) in equine urine and plasma s les is presented. The method uses liquid chromatography coupled to tandem mass spectrometry operating in electrospray ionisation positive ion mode (+ESI) via multiple reaction monitoring (MRM). S le preparation involved solid-phase extraction using a mixed-mode phase. The internal standard adopted was lignocaine-d(10). Lignocaine and its metabolites were successfully resolved using an octadecylsilica reversed-phase column using a gradient mobile phase of acetonitrile and 0.1% (v/v) aqueous formic acid at a flow rate of 300 microL/min. Target analytes and the internal standard were determined by using the following transitions lignocaine, 235.2>86.1 3-HO-LIG and 4-HO-LIG, 251.2>86.1 MEGX, 207.1>58.1 GX, 179.1>122.1 and lignocaine-d(10), 245.2>96.1. Calibration curves were generated over the range 1-100 ng/mL for plasma s les and 1-1000 ng/mL for urine s les. The method was validated for instrument linearity, repeatability and detection limit (IDL), method linearity, repeatability, detection limit (MDL), quantitation limit (LOQ) and recovery. The method was successfully used to analyse both plasma and urine s les following a subcutaneous administration of lignocaine to a thoroughbred horse.

A sensitive and high-throughput fluorescent method for determination of oxidase activities in human, bovine, goat and camel milk

Publisher: Elsevier BV

Date: 2021

DOI: 10.1016/J.FOODCHEM.2020.127689

Determination of four sulfated vitamin D compounds in human biological fluids by liquid chromatography–tandem mass spectrometry

Publisher: Elsevier BV

Date: 2016

DOI: 10.1016/J.JCHROMB.2015.12.014

Abstract: The determination of both the water-soluble and lipid-soluble vitamin D compounds in human biological fluids is necessary to illuminate potentially significant biochemical mechanisms. The lack of analytical methods to quantify the water-soluble forms precludes studies on their role and biological functions currently available liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods are able to determine only a single sulfated form of Vitamin D. We describe here a highly sensitive and specific LC-MS/MS method for the quantification of four sulfated forms of vitamin D: vitamins D2- and D3-sulfate (D2-S and D3-S) and 25-hydroxyvitamin D2- and D3-sulfate (25(OH)D2-S and 25(OH)D3-S). A comparative evaluation showed that the ionization efficiencies of underivatized forms in negative ion mode electrospray ionisation (ESI) are superior to those of the derivatized (using 4-phenyl-l,2,4-triazoline-3,5-dione (PTAD)) forms in positive ion mode ESI. Separation was optimised to minimise co-elution with endogenous matrix compounds, thereby reducing ion suppression/enhancement effects. Isotopically labelled analogues of each compound were used as internal standards to correct for ion suppression/enhancement effects. The method was validated and then applied for the analysis of breastmilk and human serum. The detection limits, repeatability standard deviations, and recoveries ranged from 0.20 to 0.28fmol, 2.8 to 10.2%, and 81.1 to 102%, respectively.

Solvent Supercritical Fluid Technologies to Extract Bioactive Compounds from Natural Sources: A Review

Publisher: MDPI AG

Date: 14-07-2017

DOI: 10.3390/MOLECULES22071186

The evaluation of integrated courseware: Can interactive molecular modelling help students understand three-dimensional chemistry?

Publisher: Elsevier BV

Date: 05-1996

DOI: 10.1016/0360-1315(95)00074-7

Estrogen modulation properties of mangiferin and quercetin and the mangiferin metabolite norathyriol

Publisher: Royal Society of Chemistry (RSC)

Date: 2015

DOI: 10.1039/C5FO00133A

Abstract: Mango fruit contain many bioactive compounds, some of which are transcription factor regulators.

Development and validation of a reversed-phase high-performance liquid chromatographic method for quantification of peptide dendrimers in human skin permeation experiments

Publisher: Elsevier BV

Date: 11-2009

DOI: 10.1016/J.JCHROMB.2009.08.039

Abstract: The aim of the present work was to develop and validate a simple RP-HPLC method with UV detection to quantify peptide dendrimers in skin permeation experiments. Six dendrimers of varying positive charges (4(+), 8(+) and 16(+)) containing either histidine or arginine as terminal aminoacids were prepared by solid phase peptide synthesis. Mobile phase containing 0.02% (v/v) heptafluorobutyric acid in 90% acetonitrile-water was capable of separating all dendrimers from interfering peaks of receptor fluid. For the calibration of each dendrimer, a different dendrimer from the same class was selected as the internal standard. The results of preliminary human skin permeation studies showed that the developed analytical method can be successfully used for the quantification of cationic poly(aminoacid)-based dendrimers in skin permeation experiments.

Traditional Aboriginal Preparation Alters the Chemical Profile of Carica papaya Leaves and Impacts on Cytotoxicity towards Human Squamous Cell Carcinoma

Publisher: Public Library of Science (PLoS)

Date: 02-2016

DOI: 10.1371/JOURNAL.PONE.0147956

Determination of para-aminohippuric acid (PAH) in human plasma and urine by liquid chromatography–tandem mass spectrometry

Publisher: Elsevier BV

Date: 10-2009

DOI: 10.1016/J.JCHROMB.2009.08.037

Abstract: In this manuscript, we present a simple and reliable method for the quantitation of para-aminohippuric acid (PAH 2-(4-aminobenzamido)acetic acid) in human plasma and urine using liquid chromatography coupled to electrospray ionisation low-energy collision-induced dissociation tandem mass spectrometry (HPLC-ESI-CID-MS/MS) analysis (negative ion mode) via multiple reaction monitoring (MRM). S le preparation involved protein precipitation of plasma s les with acetonitrile and subsequent dilution of urine s les with the mobile phase. The internal standard (IS) adopted was para-aminosalicylic acid (PAS 4-amino-2-hydroxybenzoic acid). Chromatographic separation was achieved on a Cosmosil HILIC column using an isocratic mobile phase consisting of ammonium acetate buffer (20mM) and acetonitrile (45:55, v/v) at a flow rate of 200microl/min. The transactions monitored were m/z 192.9-->149.1 for PAH and m/z 152.1-->108.1 for IS. Linear calibration curves were generated over the PAH concentration range of 0.2-100mg/L in human plasma and urine. The method was validated for selectivity, accuracy, precision, recovery and stability according to USFDA criteria, and has been successfully applied to a pharmacokinetic study in healthy volunteers administered an intravenous dose of 440mg PAH.

The Development of a High Performance Liquid Chromatographic Assay Method to Determine Pyruvate Generated During The C-S Lysis of Cysteine Conjugated Xenobiotics

Publisher: Informa UK Limited

Date: 09-1993

DOI: 10.1080/10826079308019633

The Metabolism of a Series of Ester Pro-drugs by NCTC 2544 Cells, Skin Homogenate and LDE Testskin

Publisher: Oxford University Press (OUP)

Date: 12-1994

DOI: 10.1111/J.2042-7158.1994.TB03251.X

Abstract: The metabolism of a series of substituted pyrazolopyridine ester pro-drugs was investigated using NCTC 2544 cells, human skin homogenate and LDE Testskin as model systems. The compounds were incubated in each system and the disappearance of drug and the production of the major hydrolysis product was observed with time and quantitated using HPLC. The toxicity of the ester pro-drugs and the metabolites was examined in NCTC 2544 cells using a cell viability assay procedure. Hydrolytic activity was slightly higher in the cell culture model than in skin homogenate solution but the rank order of activity for each pro-drug was similar. The metabolic activity of LDE Testskin was much reduced compared with the other systems, but again the overall pattern of metabolism was not dissimilar. These findings indicate that NCTC 2544 cells provide a reasonable model for human skin ester hydrolysis both in terms of rate and in terms of substrate specificity.

Biomolecular changes that occur in the antennal gland of the giant freshwater prawn (Machrobrachium rosenbergii)

Publisher: Public Library of Science (PLoS)

Date: 29-06-2017

DOI: 10.1371/JOURNAL.PONE.0177064

Recent trends in the determination of vitamin D

Publisher: Future Science Ltd

Date: 12-2013

DOI: 10.4155/BIO.13.283

Abstract: The occurrence of vitamin D deficiency has become an issue of serious concern in the worldwide population. As a result numerous analytical methods have been developed, for a variety of matrices, during the last few years to measure vitamin D analogs and metabolites. This review employs a comprehensive search of all vitamin D methods developed during the last 5 years for all applications, using ISI Web of Science ® , Scifinder ® , Science Direct, Scopus and PubMed. Particular emphasis is given to s le-preparation methods and the different forms of vitamin D measured across different fields of applications such as biological fluids, food and pharmaceutical preparations. This review compares and critically evaluates a wide range of approaches and methods, and hence it will enable readers to access developments across a number of applications and to select or develop the optimal analytical method for vitamin D for their particular application.

The structure and organization of lanceolate mechanosensory complexes at mouse hair follicles

Publisher: eLife Sciences Publications, Ltd

Date: 25-02-2014

DOI: 10.7554/ELIFE.01901

Abstract: In mouse hairy skin, lanceolate complexes associated with three types of hair follicles, guard, awl/auchene and zigzag, serve as mechanosensory end organs. These structures are formed by unique combinations of low-threshold mechanoreceptors (LTMRs), Aβ RA-LTMRs, Aδ-LTMRs, and C-LTMRs, and their associated terminal Schwann cells (TSCs). In this study, we investigated the organization, ultrastructure, and maintenance of longitudinal lanceolate complexes at each hair follicle subtype. We found that TSC processes at hair follicles are tiled and that in idual TSCs host axonal endings of more than one LTMR subtype. Electron microscopic analyses revealed unique ultrastructural features of lanceolate complexes that are proposed to underlie mechanotransduction. Moreover, Schwann cell ablation leads to loss of LTMR terminals at hair follicles while, in contrast, TSCs remain associated with hair follicles following skin denervation in adult mice and, remarkably, become re-associated with newly formed axons, indicating a TSC-dependence of lanceolate complex maintenance and regeneration in adults.