Gamma-tocopherol supplementation alone and in combination with alpha-tocopherol alters biomarkers of oxidative stress and inflammation in subjects with metabolic syndrome

Metabolic syndrome (MetS) is associated with increased incidence of diabetes and cardiovascular disease (CVD). Prospective clinical trials with alpha-tocopherol (AT) have not yielded positive results. Because AT supplementation decreases circulating gamma-tocopherol (GT), we evaluated supplementation with GT (800 mg/day), AT (800 mg/day), the combination or placebo for 6 weeks alone AT and GT concentrations, biomarkers of oxidative stress, and inflammation in subjects with MetS (n=20/group). Plasma AT and GT levels increased following supplementation with AT alone or GT alone or in combination. AT supplementation significantly decreased GT levels. Urinary alpha- and gamma-CEHC, metabolites of the respective Ts, also increased correspondingly, i.e., alpha-CEHC with AT and gamma-CEHC with GT supplementation, compared to placebo. HsCRP levels significantly decreased in the combined AT+GT group. LPS-activated whole blood release of IL-1 and IL-6 did not change. There was a significant decrease in TNF with AT alone or in combination with GT. Plasma MDA/HNE and lipid peroxides were significantly decreased with AT, GT, or in combination. Nitrotyrosine levels were significantly decreased only with GT or GT+AT but not with AT compared to placebo. Thus, the combination of AT and GT supplementation appears to be superior to either supplementation alone on biomarkers of oxidative stress and inflammation and needs to be tested in prospective clinical trials to elucidate its utility in CVD prevention.     

Nutritional status assessment in complete denture wearers

doi: 10.1111/j.1741‐2358.2011.00620.x Nutritional status assessment in complete denture wearers Background and objectives: The relationship between oral health and the nutritional status in the elderly is complex and controversial. It has been suggested that poor oral health and a decreased ability to chew have a profound influence on food selection, diet and thereby the nutritional status of the individual. This study aimed to evaluate the effect of edentulousness and prosthetic treatment on the nutritional status of the individual. Methods: A total of 94 patients were selected for the study, which was conducted over a period of 16 months. The nutritional status was assessed using the Mini Nutritional Assessment Form (MNA) before the complete denture treatment and after an interval of 6 months and 9 months following the treatment. The individual scores obtained for each question and the total scores at the baseline study were compared with those obtained after 6 and 9 months. Proportions were compared using chi‐squared test of significance. Results: The results showed statistically significant differences in the total MNA scores between the baseline study and after 6 and 9 months. The edentulous patients without complete dentures had significantly lower MNA scores. Conclusion: Prosthetic rehabilitation of the edentulous patients with complete dentures, along with the dietary counselling, improved the nutritional status of these patients.     

Functions of the water soluble chlorophyll-binding protein in plants

Functional aspects of water soluble chlorophyll-binding protein (WSCP) in plants were investigated during the courses of leaf senescence, chlorophyll biogenesis, stress response and photoprotection. The cDNA sequence encoding WSCP from cauliflower was cloned into a binary vector to facilitate Agrobacterium tumefaciens mediated transformation of Nicotiana tabacum. The resultant transgenic tobacco plants overexpressed the CauWSCP gene under the control of a 35S-promoter. Analyses of protein and pigment contents indicate that WSCP overexpression does not enhance chlorophyll catabolism in vivo, thus rendering a role of WSCP in Chl degradation unlikely. Accumulation of higher levels of protochlorophyllide in WSCP overexpressor plants corroborates a proposed temporary storage and carrier function of WSCP for chlorophyll and late precursors. Although WSCP overexpressor plants did not show significant differences in non-photochemical quenching of chlorophyll fluorescence, they are characterized by significantly lower zeaxanthin accumulation and peroxidase activity at different light intensities, even at high light intensities of 700-900 μmol photons m⁻² s⁻¹. These results suggest a photoprotective function of the functional chlorophyll binding-WSCP tetramer by shielding of chlorophylls from molecular oxygen.     

Mechanism of diepoxybutane‐induced p53 regulation in human cells

Diepoxybutane (DEB) is the most potent active metabolite of the environmental chemical 1,3‐butadiene (BD). BD is a known mutagen and human carcinogen and possesses multisystems organ toxicity. We previously reported the elevation of p53 in human TK6 lymphoblasts undergoing DEB‐induced apoptosis. In this study, we have characterized the DEB‐induced p53 accumulation and investigated the mechanisms by which DEB regulates this p53 accumulation. The elevation of p53 levels in DEB‐exposed TK6 lymphoblasts and human embryonic lung (HEL) human fibroblasts was found to be largely due to the stabilization of the p53 protein. DEB increased the acetylation of p53 at lys‐382, dramatically reduced complex formation between p53 and its regulator protein mdm2 and induced the phosphorylation of p53 at serines 15, 20, 37, 46, and 392 in human lymphoblasts. A dramatic increase in phosphorylation of p53 at serine 15 in correlation to total p53 levels was observed in DEB‐exposed Ataxia Telangiectasia Mutated (ATM) proficient human lymphoblasts as compared to DEB‐exposed ATM‐deficient human lymphoblasts; this implicates the ATM kinase in the elevation of p53 levels in DEB‐exposed cells. Collectively, these findings explain for the first time the mechanism by which p53 accumulates in DEB‐exposed cells and contributes to the understanding of the molecular toxicity of DEB and BD. © 2009 Wiley Periodicals, Inc. J Biochem Mol Toxicol 23:373–386, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jbt.20300     

Intersubunit Disulfide Interactions Play a Critical Role in Maintaining the Thermostability of Glucose-6-phosphate Dehydrogenase from the Hyperthermophilic Bacterium Aquifex aeolicus

Proteins from thermophilic microorganisms are stabilized by various mechanisms to preserve their native folded states at higher temperatures. A thermostable glucose-6-phosphate dehydrogenase (tG6PDH) from the hyperthermophilic bacterium Aquifex aeolicus was expressed as a recombinant protein in Escherichia coli. The A. aeolicus G6PDH is a homodimer exhibiting remarkable thermostability (t_1/2=24 hr at 90°C). Based on homology modeling and upon comparison of its structure with human G6PDH, it was predicted that cysteine 184 of one subunit could form a disulfide bond with cysteine 352 of the other subunit resulting in reinforced intersubunit interactions that hold the dimer together. Site-directed mutagenesis was performed on tG6PDH to convert C184 and C352 to serines. The tG6PDH double mutant exhibited a dramatic decrease in the half-life from 24 hr to 3 hr at 90°C. The same decrease in half-life was also found when either C184 or C352 was mutated to serine. The result indicates that C184 and C352 may play a crucial role in strengthening the dimer interface through disulfide bond formation, thereby contributing to the thermal stability of the enzyme.     

CRP promotes monocyte-endothelial cell adhesion via Fcgamma receptors in human aortic endothelial cells under static and shear flow conditions

Monocyte-endothelial cell adhesion is a key early event in atherogenesis. C-reactive protein (CRP), a cardiovascular risk marker, is known to stimulate ICAM and VCAM in human aortic endothelial cells (HAEC) and induces monocyte-endothelial cell adhesion. In this study, we examined the mechanisms by which native CRP promotes monocyte-endothelial cell adhesion under static conditions and tested the effect of CRP on adhesion under shear flow. Incubation of HAEC with CRP (>25 microg/ml) upregulated NF-kappaB activity, and this resulted in a significant increase in ICAM (54% increase, P<0.001), VCAM (41% increase, P<0.01), and monocyte-endothelial cell adhesion (44% increase, P<0.02) compared with those of control. Preincubation with antibodies to CD32 and CD64 but not CD16 effectively inhibited this activation. Blocking NF-kappaB activity with inhibitors or a dominant negative inhibitory kappaB significantly decreased ICAM, VCAM upregulation, and subsequent monocyte-endothelial cell adhesion. Preincubation with antibodies to CD32 and CD64 or transient transfection with small interference RNA to CD32 attenuated CRP-induced NF-kappaB activity, ICAM, VCAM, and monocyte-endothelial cell adhesion under static conditions. Also, the Syk kinase inhibitor piceatannol and MG-132, a proteasome degradation inhibitor, produced similar attenuation in NF-kappaB activity, ICAM, VCAM, and adhesion. Furthermore, CRP-activated endothelial cells supported monocyte rolling, arrest, and transmigration in shear flow (2 dyn/cm2), and this was also inhibited by preincubation with antibodies to CD32 and CD64. Thus, in HAEC, CRP upregulates monocyte-endothelial adhesion by activation of NF-kappaB through engaging the Fcgamma receptors CD32 and CD64.     

Synthesis and structure-activity relationships of andrographolide analogues as novel cytotoxic agents

Andrographolide 1, the cytotoxic agent of the plant Andrographis paniculata was subjected to semi-synthetic studies leading to the preparation of a number of potent and novel analogues. Of the analogues synthesized, while 8,17-epoxy andrographolide 6 retained the cytotoxic activity of 1, ester derivatives of 6 exhibited considerable improvement in activity. Lower activity was observed when the epoxy moiety in the triacetate 9, derived from 6 was modified. Synthesis and structure-activity relationships are discussed.