Accelerated aging as evidenced by increased telomere shortening and mitochondrial DNA depletion in patients with type 2 diabetes

Although shortened telomeres were shown associated with several risk factors of diabetes, there is lack of data on their relationship with mitochondrial dysfunction. Therefore, we compared the relationship between telomere length and mitochondrial DNA (mtDNA) content in patients with type 2 diabetes mellitus (T2DM; n = 145) and in subjects with normal glucose tolerance (NGT; n = 145). Subjects were randomly recruited from the Chennai Urban Rural Epidemiology Study. mtDNA content and telomere length were assessed by Real-Time PCR. Malonodialdehyde, a marker of lipid peroxidation was measured by thiobarbituric acid reactive substances (TBARS) using fluorescence methodology. Adiponectin levels were measured by radioimmunoassay. Oxidative stress as determined by lipid peroxidation (TBARS) was significantly (p < 0.001) higher in patients with T2DM compared to NGT subjects. In contrast, the mean telomere length, adiponectin and mtDNA content were significantly (p < 0.001) lower in patients with T2DM compared to NGT subjects. Telomere length was positively correlated with adiponectin, HDL, mtDNA content and good glycemic/lipid control and negatively correlated with adiposity and insulin resistance. On regression analysis, shortened telomeres showed significant association with T2DM even after adjusting for waist circumference, insulin resistance, triglyceride, HDL, adiponectin, mtDNA & TBARS. mtDNA depletion showed significant association with T2DM after adjusting for waist circumference and adiponectin but lost its significance when further adjusted for telomere length, TBARS and insulin resistance. Our study emphasizes the clustering of accelerated aging features viz., shortened telomeres, decreased mtDNA content, hypoadiponectinemia, low HDL, and increased oxidative stress in Asian Indian type 2 diabetes patients.     

Impact of low and high fluence rates of UV-B radiation on growth and oxidative stress in Phormidium foveolarum and Nostoc muscorum under copper toxicity: differential display of antioxidants system

In the present study, impact of low (UV-B_L) and high (UV-B_H) fluence rates of UV-B on growth, oxidative stress and antioxidant system was studied in two cyanobacteria i.e. Phormidium foveolarum and Nostoc muscorum under Cu (2 and 5???M) toxicity after 24 and 72?h of experiments. UV-B_H and Cu treatment decreased growth of both the cyanobacteria and Cu induced decrease in growth was accompanied by a significant increase in Cu accumulation. Levels of reactive oxygen species (ROS), i.e. superoxide radicals (SOR; $ \text O_{2}^{\cdot\,-} $ ) and hydrogen peroxide (H₂O₂) were significantly increased by Cu and UV-B_H exposure which in turn accelerated lipid peroxidation (malondialdehyde: MDA) and protein oxidation (reactive carbonyl groups: RCG). Activities of enzymatic antioxidants, such as superoxide dismutase (SOD), peroxidase (POD) and glutathione-S-transferase (GST) were increased by both doses of Cu as well as UV-B. Conversely, Cu and UV-B_H drastically decreased catalase (CAT) activity. After the commencement of 24?h of treatment with Cu alone and together with UV-B_H, non-protein thiols (NP-SH) contents were decreased while after 72?h, a reverse trend was noticed. Unlike NP-SH, cysteine content decreased appreciably during the treatments. In contrast to this, low dose (UV-B_L) of UV-B did not influence growth, SOR, H₂O₂, MDA and RCG contents. An improvement in CAT activity and NP-SH content was observed under Cu and UV-B_L treatment; hence, UV-B_L treatment resulted into certain degree of protection against Cu toxicity in both the organisms. Thus, the results showed that UV-B_H and UV-B_L exerted differential effects on both the organisms under Cu toxicity, and compared to N. muscorum, P. foveolarum was less affected by Cu and UV-B_H.     

Biological characterization of lead-enhanced exopolysaccharide produced by a lead resistant Enterobacter cloacae strain P2B

A lead resistant bacterial strain isolated from effluent of lead battery manufacturing company of Goa, India has been identified as Enterobacter cloacae strain P2B based on morphological, biochemical characters, FAME profile and 16S rDNA sequence data. This bacterial strain could resist lead nitrate up to 1.6?mM. Significant increase in exopolysaccharide (EPS) production was observed as the production increased from 28 to 108?mg/L dry weight when exposed to 1.6?mM lead nitrate in Tris buffered minimal medium. Fourier-transformed infrared spectroscopy of this EPS revealed presence of several functional groups involved in metal binding viz. carboxyl, hydroxyl and amide groups along with glucuronic acid. Gas chromatography coupled with mass spectrometry analysis of alditol-acetate derivatives of acid hydrolysed EPS produced in presence of 1.6?mM lead nitrate demonstrated presence of several neutral sugars such as rhamnose, arabinose, xylose, mannose, galactose and glucose, which contribute to lead binding hydroxyl groups. Scanning electron microscope coupled with energy dispersive X-ray spectrometric analysis of this lead resistant strain exposed to 1.6?mM lead nitrate interestingly revealed mucous EPS surrounding bacterial cells which sequestered 17?% lead (as weight %) extracellularly and protected the bacterial cells from toxic effects of lead. This lead resistant strain also showed multidrug resistance. Thus these results significantly contribute to better understanding of structure, function and environmental application of lead-enhanced EPSs produced by bacteria. This lead-enhanced biopolymer can play a very important role in bioremediation of several heavy metals including lead.     

Continuous exposure to l-arginine induces oxidative stress and physiological tolerance in cultured human endothelial cells

The therapeutic benefits of L-arginine (ARG) supplementation in humans, often clearly observed in short-term studies, are not evident after long-term use. The mechanisms for the development of ARG tolerance are not known and cannot be readily examined in humans. We have developed a sensitive in vitro model using a low glucose/low arginine culture medium to study the mechanisms of ARG action and tolerance using two different human endothelial cells, i.e., Ea.hy926 and human umbilical venous endothelial cells. Cultured cells were incubated with different concentrations of ARG and other agents to monitor their effects on endothelial nitric oxide synthase (eNOS) expression and function, as well as glucose and superoxide (O2(·-) ) accumulation. Short-term (2 h) exposure to at least 50 μM ARG moderately increased eNOS activity and intracellular glucose (p < 0.05), with no change in eNOS mRNA or protein expression. In contrast, 7-day continuous ARG exposure suppressed eNOS expression and activity. This was accompanied by increase in glucose and O2(·-) accumulation. Co-incubation with 100 μM ascorbic acid, 300 U/ml polyethylene glycol-superoxide dismutase (PEG-SOD), 100 μM L-lysine or 30 μM 5-chloro-2-(N-2,5-dichlorobenenesulfonamido)-benzoxazole (a fructose-1,6-bisphosphatase inhibitor) prevented the occurrence of cellular ARG tolerance. Short-term co-incubation of ARG with PEG-SOD improved cellular nitrite accumulation without altering cellular ARG uptake. These studies suggest that ARG-induced oxidative stress may be a primary causative factor for the development of cellular ARG tolerance.     

Synergistic effects of amyloid peptides and lead on human neuroblastoma cells

Aggregated amyloid peptides (AP), major components of senile plaques, have been considered to play a very important and crucial role in the development and neuro-pathogenesis of Alzheimer's disease (AD). In the present in vitro, study the synergistic effects of Pb(2+), a heavy metal, and AP on the human neuroblastoma SH-SY5Y cells were investigated. The cells treated with Pb(2+) (0.01-10 μM) alone exhibited a significant decrease in viability and IC(50) was 5 μM. A similar decrease in viability was also observed when the cells were exposed to AP, Aβ1-40 (20-120 μM) and Aβ25-35 (2.5-15 μM) for 48 hrs. The IC(50) values were 60 μM and 7.5 μM for Aβ1-40 and Aβ25-35 respectively. To assess the synergistic effects the cells were exposed to IC(50) of both AP and Pb(2+), which resulted in further reduction of the viability. The study was extended to determine the lactate dehydrogenase (LDH) release to assess the cytotoxic effects, 8-isoprostane for extent of oxidative damage, COX 1 and 2 for inflammation related changes, p53 protein for DNA damage and protein kinases A and C for signal transduction. The data suggest that the toxic effects of AP were most potent in the presence of Pb(2+), resulting in an aggravated clinical pathological condition. This could be attributed to the oxidative stress, inflammation neuronal apoptosis and an alteration in the activities of the signaling enzymes.     

Atherogenic effect of Arecoline: A computational study

There are over 600 million people worldwide covering Asian and Oceanic countries including India have the habit of chewing areca nut as masticator in different forms. Arecoline (C(8)H(13)NO(2)) has been reported as one of the abundant constituents of areca nut. A good number of scientific publications have made Arecoline responsible for oral cancer. Based on observation from clinical situation in North East India, one of the most betel quid chewing region of the country, we suspected a link between consumption of areca nut and Cerebro Vascular Disease like stroke. Therefore, we considered Low Density Lipoprotein (LDL) receptor as target and Arecoline as ligand and studied ligand -target interaction using computational tools. Also we considered High Density Lipoprotein (HDL) receptor as another target to see if Arecoline has any binding potential with it over and above LDL receptor. Docking result indicated that Arecoline and Cholesterol both, have affinity towards extracellular domain of Human LDL receptor but affinity of Arecoline is much higher (-12.3560.) than that of Cholesterol(-0.1810). Docking of Arecoline and 1, 2-Hexyl-1- cyclopentanone thiosemicarbazone (thiosemicarbazone) with Bovine HDL receptor showed that Arecoline also has the potential (Score, -6.2690Kcal/Mol) to block HDL receptor though its potential is less than that (score, -10.0509 Kcal/Mol) of control (thiosemicarbazone). We, therefore, suggest that by inhibiting endocytosis of LDL cholesterol because of blocking LDL receptor function and also by preventing LDL cholesterol uptake by liver from blood because of interference with HDL receptor, Arecoline may contribute to atherosclerosis. The study therefore, indicates a positive correlation between chewing of betel quid and Cerebro Vascular Disease.     

No Pain Relief with the Rubber Hand Illusion

The sense of body ownership can be easily disrupted during illusions and the most common illusion is the rubber hand illusion. An idea that is rapidly gaining popularity in clinical pain medicine is that body ownership illusions can be used to modify pathological pain sensations and induce analgesia. However, this idea has not been empirically evaluated. Two separate research laboratories undertook independent randomized repeated measures experiments, both designed to detect an effect of the rubber hand illusion on experimentally induced hand pain. In Experiment 1, 16 healthy volunteers rated the pain evoked by noxious heat stimuli (5 s duration; interstimulus interval 25 s) of set temperatures (47°, 48° and 49°C) during the rubber hand illusion or during a control condition. There was a main effect of stimulus temperature on pain ratings, but no main effect of condition (p = 0.32), nor a condition x temperature interaction (p = 0.31). In Experiment 2, 20 healthy volunteers underwent quantitative sensory testing to determine heat and cold pain thresholds during the rubber hand illusion or during a control condition. Secondary analyses involved heat and cold detection thresholds and paradoxical heat sensations. Again, there was no main effect of condition on heat pain threshold (p = 0.17), nor on cold pain threshold (p = 0.65), nor on any of the secondary measures (p<0.56 for all). We conclude that the rubber hand illusion does not induce analgesia.