ORCID Profile
0000-0002-4569-876X
Current Organisation
The Hong Kong Polytechnic University Faculty of Science
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Publisher: Elsevier BV
Date: 07-2010
Publisher: Public Library of Science (PLoS)
Date: 17-06-2013
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.JNUTBIO.2009.06.015
Abstract: Folic acid supplementation provides beneficial effects on endothelial functions in patients with hyperhomocysteinemia. However, its effects on vascular functions under diabetic conditions are largely unknown. Therefore, the effect(s) of folic acid (5.7 and 71 microg/kg/day for 4 weeks) on aortic relaxation was investigated using obese/diabetic (+db/+db) mice and lean littermate (+db/+m) mice. Acetylcholine-induced relaxation in +db/+db mice was less than that observed in +db/+m mice. The reduced relaxation in +db/+db mice was restored by consumption of 71 microg/kg folic acid. Acetylcholine-induced relaxation (with and without folic acid treatment) was sensitive to N(G)-nitro-L-arginine methyl ester, 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one, geldanamycin and triciribine. In addition, acetylcholine-induced relaxation was attenuated by resistin. The plasma level of resistin in +db/+db mice was sevenfold higher than that measured in +db/+m mice, and the elevated plasma level of resistin in +db/+db mice was reduced by 25% after treatment with 71 microg/kg folic acid. Folic acid slightly increased the ratio of reduced glutathione to oxidized glutathione in +db/+db mice. Moreover, folic acid caused a reduction in PTEN (phosphatase and tensin homolog deleted on chromosome 10) expression, an increase in the phosphorylation of endothelial nitric oxide synthase (eNOS(Ser1177)) and Akt(Ser473), and an enhanced interaction of heat shock protein 90 (HSP90) with eNOS in both strains, with greater magnitude observed in +db/+db mice. In conclusion, folic acid consumption improved blunted acetylcholine-induced relaxation in +db/+db mice. The mechanism may be, at least partly, attributed to enhancement of PI3K/HSP90/eNOS/Akt cascade, reduction in plasma resistin level, down-regulation of PTEN and slight modification of oxidative state.
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.EJPHAR.2015.09.048
Abstract: In this study, we evaluated the anabolic effect and the underlying cellular mechanisms involved of vitamin K2 (10 nM) and 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) (10 nM), alone and in combination, on primary osteoblasts harvested from the iliac crests of C57BL/KsJ lean (+/+) and obese/diabetic (db/db) mice. A lower alkaline phosphatase (ALP) activity plus a reduced expression of bone anabolic markers and bone formation transcription factors (osteocalcin, Runx2, Dlx5, ATF4 and OSX) were consistently detected in osteoblasts of db/db mice compared to lean mice. A significantly higher calcium deposits formation in osteoblasts was observed in lean mice when compared to db/db mice. Co-administration of vitamin K2 (10 nM) and 1,25(OH)2D3 (10 nM) caused an enhancement of calcium deposits in osteoblasts in both strains of mice. Vitamins K2 and 1,25(OH)2D3 co-administration time-dependently (7, 14 and 21 days) increased the levels of bone anabolic markers and bone formation transcription factors, with a greater magnitude of increase observed in osteoblasts of db/db mice. Combined vitamins K2 plus 1,25(OH)2D3 treatment significantly enhanced migration and the re-appearance of surface microvilli and ruffles of osteoblasts of db/db mice. Thus, our results illustrate that vitamins K2 plus D3 combination could be a novel therapeutic strategy in treating diabetes-associated osteoporosis.
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.JNUTBIO.2009.03.010
Abstract: We evaluated the vasorelaxation effects of formononetin, an isoflavone hytoestrogen found abundantly in Astragalus mongholicus Bunge, on rat isolated aorta and the underlying mechanisms involved. Cumulative administration of formononetin, genistein, daidzein and biochanin A relaxed phenylephrine-preconstricted aorta. Formononetin and biochanin A caused a similar magnitude of relaxation whereas daidzein was least potent. Mechanical removal of endothelium, L-NAME (100 microM) and methylene blue (10 microM) suppressed formononetin-induced relaxation. Formononetin increased endothelial nitric oxide (NO) synthase (eNOS), but not inducible NO synthase, activity with an up-regulation of eNOS mRNA and p-eNOS(Ser1177) protein expression. In endothelium-denuded preparations, formononetin-induced vasorelaxation was significantly reduced by glibenclamide (3 microM) and iberiotoxin (100 nM), and a combination of glibenclamide (3 microM) plus iberiotoxin (100 nM) abolished the relaxation. In contrast, formononetin-elicited endothelium-independent relaxation was not altered by ICI 182,780 (10 microM, an estrogen receptor (ER alpha/ER beta) antagonist) or mifepristone (10 microM, a progesterone receptor antagonist). In single aortic smooth muscle cells, formononetin caused opening of iberiotoxin-sensitive Ca(2+)-activated K(+) (BK(Ca)) channels and glibenclamide-sensitive adenosine triphosphate (ATP)-dependent K(+) (K(ATP)) channels. Thus, our results suggest that formononetin caused vascular relaxation via endothelium/NO-dependent mechanism and endothelium-independent mechanism which involves the activation of BK(Ca) and K(ATP) channels.
Publisher: SAGE Publications
Date: 09-2009
DOI: 10.3181/0902-RM-44
Abstract: The effects of folic acid (5.7 and 71 μg/kg, 4 weeks) consumption on the β-adrenoceptors (β-ARs)–elicited lipolysis in vitro of the abdominal adipocytes of lean/control (+ m/+ db) and obese/diabetic (+ db/+ db) mice (female) were investigated. β-AR agonists (salbutamol, a β 2 -AR agonist BRL 37344 and CGP 12177, β 3 -AR agonists adrenaline, a β-AR agonist)–mediated lipolysis, β 2 -, and β 3 -ARs protein expression of the adipose tissues after folic acid consumption were evaluated. Our results demonstrate that a smaller magnitude of the basal (spontaneous) and the β-AR agonists–triggered lipolysis was observed in + db/+ db mice, and folic acid supplementation (71 μg/kg) resulted in an improvement of both the baseline and the β-ARs–mediated lipolysis. In controls, a lower β 2 -and β 3 -ARs protein expression of the adipose tissues was detected in + db/+ db mice, compared to + m/+ db mice. In both strains fed with folic acid (71 μg/kg), a reduction of β 2 -AR protein expression was observed compared to the respective controls. In + db/+ db mice, folic acid (5.7 and 71 μg/kg) consumption caused a dose-dependent increase of β 3 -AR protein expression compared to controls. We demonstrate that lipolysis elicited by β-AR (β 2 - and β 3 -ARs) agonists was blunted in + db/+ db mice. Folic acid consumption has significant modulatory effects on β-ARs protein expression and lipolysis.
Publisher: Wiley
Date: 24-06-2010
Publisher: World Scientific Pub Co Pte Lt
Date: 2010
DOI: 10.1142/S0192415X10008263
Abstract: In Chinese communities, regular consumption of Chinese-medicated diets (CMD) (usually in the form of soup) is a traditional practice to promote health and prevent disease development. The overall improvement of health conditions is believed to be correlated with the anti-oxidant potentials of these herbs. Huangqin, roots of Scutellaria baicalensis Georgi (Lamiaceae), is one of the herbs commonly used in CMD. In this study, the anti-oxidant capacities of Huangqin extracts (water, ethanol and ether extracts) were evaluated and compared to commonly used CMD herbs, Heshouwu, roots of Polygonum multiflorum Thunb (Polygonaceae) and Renshen (or Ginseng), roots of Panax ginseng CA Meyer (Araliaceae). The anti-oxidant capacities were measured by using both cell-free assay [ferric reducing/anti-oxidant power (FRAP)] and biological methods [2,2'-azobis–(2-amidinopropane) (AAPH)-induced haemolysis assay and H 2 O 2 -induced cell damage on H9C2 cells]. Additionally, the total phenolic content was measured using Folin-Ciocalteu methods. Water extract of Huangqin has the highest anti-oxidant activities compared to the ethanol and ether extracts. A positive relationship between the anti-oxidant effects and total phenolic contents of extracts was demonstrated. This shows that Huangqin could be an effective dietary anti-oxidant that can be consumed regularly as a functional food for the prevention of oxidant/free radical-related diseases.
Location: Hong Kong
Location: Hong Kong
Location: Hong Kong
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Chui Wa Christina Poon.