ORCID Profile
0000-0001-9175-9052
Current Organisation
Flinders University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Oxford University Press (OUP)
Date: 26-04-2023
DOI: 10.1093/JAC/DKAD121
Abstract: To elucidate the importance of a region in QacA predicted to be important in antimicrobial substrate recognition. A total of 38 amino acid residues within or flanking putative transmembrane helix segment (TMS) 12 of QacA were in idually replaced with cysteine using site-directed mutagenesis. The impact of these mutations on protein expression, drug resistance, transport activity and interaction with sulphhydryl-binding compounds was determined. Accessibility analysis of cysteine-substituted mutants identified the extents of TMS 12, which allowed for refinement of the QacA topology model. Mutation of Gly-361, Gly-379 and Ser-387 in QacA resulted in reduced resistance to at least one bivalent substrate. Interaction with sulphhydryl-binding compounds in efflux and binding assays demonstrated the role of Gly-361 and Ser-387 in the binding and transport pathway of specific substrates. The highly conserved residue Gly-379 was found to be important for the transport of bivalent substrates, commensurate with the role of glycine residues in helical flexibility and interhelical interactions. TMS 12 and its external flanking loop is required for the structural and functional integrity of QacA and contains amino acids directly involved in the interaction with substrates.
Publisher: Springer Science and Business Media LLC
Date: 19-04-2023
DOI: 10.1038/S41598-023-33625-X
Abstract: Green synthesized nanoparticles (GSNPs) display fascinating properties compared to physical and chemical synthesized ones. GSNPs are currently used in numerous applications such as food packaging, surface coating agents, environmental remediation, antimicrobial, and medicine. In the present study, the aqueous leaf extract of Perilla frutescens L. having suitable capping, reducing, and stabilizing compounds was used for green synthesis of silver nanoparticles (Pf-AgNPs). The bioreductant capacity of aqueous leaf extract of P. frutescens for Pf-AgNPs was determined by different confirmatory techniques including UV–Visible spectroscopy, XRD, FESEM, EDX, zeta potential, DLS, SERS, and FTIR analysis. The results exhibited that Pf-AgNPs had optimal size ( 61 nm), shape (spherical), and stability (− 18.1 mV). The antioxidant activity of Pf-AgNPs with both DPPH and FRAP assays was significantly higher compared to P. frutescens extract. Furthermore, Pf-AgNPs had high antimicrobial activity against Escherichia coli and Staphylococcus aureus (MIC = 0.78 mg/mL), and Candida albicans (MIC = 8 mg/mL) while the plant extract showed low antimicrobial activity against both bacterial strains and the fungus tested. Pf-AgNPs and P. frutescens extract also exhibited moderate toxicity on MCF-7 cancer cells with IC 50 values of 346.2 and 467.4 µg/mL, respectively. The results provide insights into using the biosynthesized Pf-AgNPs as an eco-friendly material for a wide range of biomedical applications.
Publisher: Science Alert
Date: 15-12-2011
Publisher: Bentham Science Publishers Ltd.
Date: 04-2013
DOI: 10.2174/1573406411309040006
Abstract: Tumor and especially breast cancer is among the most common causes of death worldwide. Finding novel nanosized therapeutic compounds have important role to decrease the chance of death and increase the survival. Cancer cells are highly attractive to glucose [with a nanosize bimolecular structure 1nm] as an energy source more than normal cell and nanosized therapeutics due to possessing different pharmacokinetic and pharmacodynamic have advantageous over classical dosage forms in cancer therapy. The aim of the study was to synthesize Glucosamin-Porphyrin-Tamoxifen [TPG] nanosized complex as a novel selective biocompatible anti breast cancer agent. After the synthesis procedure, this complex was purified and then tested In Vitro on breast cancer cells [MCF-7] in the absence or presence of the red light and found totally successful. The results showed a good anti breast cancer activity mediated by the activation of TNF-α and necrosis/apoptosis pathways for the nanosized complex with no alteration effects on blood PT/APTT and glucose or hexokinase levels/ activity. TPG nanoconjugate seems to be very good opponents to current anti breast cancer drugs and needs to be further investigated in near future.
Publisher: MDPI AG
Date: 02-08-2022
Abstract: Plant-derived pharmacological agents have been used extensively to dissect the structure–function relationships of mammalian GABA receptors and ion channels. Picrotoxin is a non-competitive antagonist of mammalian GABAA receptors. Here, we report that picrotoxin inhibits the anion (malate) efflux mediated by wheat (Triticum aestivum) ALMT1 but has no effect on GABA transport. The EC50 for inhibition was 0.14 nM and 0.18 nM when the ALMTs were expressed in tobacco BY2 cells and in Xenopus oocytes, respectively. Patch cl ing of the oocyte plasma membrane expressing wheat ALMT1 showed that picrotoxin inhibited malate currents from both sides of the membrane. These results demonstrate that picrotoxin inhibits anion efflux effectively and can be used as a new inhibitor to study the ion fluxes mediated by ALMT proteins that allow either GABA or anion transport.
Publisher: Springer Science and Business Media LLC
Date: 09-02-2013
DOI: 10.1007/S00284-013-0324-7
Abstract: Sequence analysis of dnaE, hlyA, and asd housekeeping genes were used to determine the genetic relatedness of our collection of Vibrio cholerae isolated from patients and surface waters over a 5-year period in Iran. The results showed 41, 17, and 9 variable sites throughout the sequenced fragments of dnaE (837 bp), hlyA (495 bp), and asd (295 bp), respectively. The results from sequence typing showed that all our clinical isolates were grouped in the same cluster. Eleven genotypes were identified among the environmental isolates. One environmental isolate was found to be in close genetic relatedness with our clinical isolates. One V. cholerae isolate showed a single-locus variant in the dnaE. For each of the studied genetic loci 10, 7, and 7 sequence types were observed for dnaE, hlyA, and asd, respectively. Only asd sequence analysis could make the distinction between the classical and El Tor isolates which emphasizes on selection of housekeeping locus with better discrimination power for analysis of different groups of isolates. Overall, the results indicated that surface waters in Tehran are a pool of non-toxigenic V. cholerae strains which are rarely related to clinical toxigenic isolates. In addition, our results verified that housekeeping gene sequence analysis could be a suitable approach for determination of the relatedness between clinical and environmental V. cholerae isolates.
Publisher: Elsevier BV
Date: 12-2008
Publisher: MDPI AG
Date: 07-12-2021
DOI: 10.3390/ANTIBIOTICS10121502
Abstract: The increasing emergence of antimicrobial resistance in staphylococcal bacteria is a major health threat worldwide due to significant morbidity and mortality resulting from their associated hospital- or community-acquired infections. Dramatic decrease in the discovery of new antibiotics from the pharmaceutical industry coupled with increased use of sanitisers and disinfectants due to the ongoing COVID-19 pandemic can further aggravate the problem of antimicrobial resistance. Staphylococci utilise multiple mechanisms to circumvent the effects of antimicrobials. One of these resistance mechanisms is the export of antimicrobial agents through the activity of membrane-embedded multidrug efflux pump proteins. The use of efflux pump inhibitors in combination with currently approved antimicrobials is a promising strategy to potentiate their clinical efficacy against resistant strains of staphylococci, and simultaneously reduce the selection of resistant mutants. This review presents an overview of the current knowledge of staphylococcal efflux pumps, discusses their clinical impact, and summarises compounds found in the last decade from plant and synthetic origin that have the potential to be used as adjuvants to antibiotic therapy against multidrug resistant staphylococci. Critically, future high-resolution structures of staphylococcal efflux pumps could aid in design and development of safer, more target-specific and highly potent efflux pump inhibitors to progress into clinical use.
Publisher: Elsevier BV
Date: 09-2011
Publisher: Elsevier BV
Date: 07-2012
Abstract: The aim of this study was to understand the epidemiological linkage of clinical and environmental isolates of Vibrio cholerae and to determine their genotypes and virulence genes content. A total of 60 V. cholerae strains obtained from clinical specimens (n = 40) and surface waters (n = 20) were subjected to genotyping using PFGE and determination of their virulence-associated gene clusters. PCR analysis showed the presence of chromosomally located hly and RTX genetic elements in 100% and 90% of the environmental isolates, respectively. The phage-mediated genetic elements such as CTX, TLC and VPI were detected in 5% of the environmental isolates suggesting that the environmental isolates cannot acquire certain mobile gene clusters. A total of 4 and 18 pulsotypes were obtained among the clinical and environmental V. cholerae isolates, respectively. Non-pathogenic environmentally isolated V. cholerae constituted a distinct cluster with one single non-O1, non-O139 strain (EP6) carrying the virulence genes similar to the epidemic strains. This may suggest the possible potential of conversion of non-pathogenic to a pathogenic environmental strain. The emergence of a single environmental isolate in our study containing the pathogenicity genes amongst the erse non-pathogenic environmental isolates needs to be further studied in the context of V. cholerae pathogenicity sero-coversion.
Publisher: Elsevier BV
Date: 2012
Abstract: Vibrio cholerae, the cause of cholera, is one of the leading causes of morbidity and mortality in many developing countries. Most laboratories initially rely on biochemical tests for a presumptive identification of these strains, followed by a polymerase chain reaction (PCR)-based method to confirm their identification. The aim of this study is to establish a rapid and reliable identification scheme for V. cholerae using a minimal, but highly specific number of biochemical tests and a PCR assay. We developed a species-specific PCR to identify V. cholerae, using a housekeeping gene recA, and used that to evaluate the sensitivity and specificity of 12 biochemical tests commonly used for screening and / or presumptive identification of V. cholerae in the clinical and environmental s les. Here we introduced a combination of three biochemical tests, namely, sucrose fermentation, oxidase test, and growth in trypton broth containing 0% NaCl, as also the PCR of the recA gene, for rapid identification of V. cholerae isolates, with 100% sensitivity and specificity. The established method accurately identified a collection of 47 V. cholerae strains isolated from the clinical cases (n = 26) and surface waters (n = 21), while none of the 32 control strains belonging to different species were positive in this assay. The triple-test procedure introduced here is a simple and useful assay which can be adopted in cholera surveillance programs for efficient monitoring of V. cholerae in surface water and fecal s les.
Publisher: Informa UK Limited
Date: 07-2012
DOI: 10.4161/HV.20166
Abstract: Nowadays adjuvants are extensively used as immuno-stimulatory and immuno-modulatory compounds as components of subunit and combination vaccine formulations. The adjuvants of microbial origin are more frequently used among currently used licensed or experimental adjuvants. The outer membrane vesicle (OMV) of Neisseria meningitidis is among the newly studied components of microbial origin, which could be applied as an adjuvant. Although the potency of OMV as a carrier (conjugated to a hapten) is now proven, the adjuvant properties of OMV have particular significance as a potential target for protective immunity. Since it has immune-stimulatory activity, OMV has been utilized in vaccine development. This commentary reviews the different applications of OMV as potential adjuvant in the field of vaccine development.
Publisher: Oxford University Press (OUP)
Date: 25-07-2011
No related grants have been discovered for Abolfazl Dashtbani-Roozbehani.