Characterization of palmitic acid toxicity induced insulin resistance in HepG2 cells

BACKGROUND

An etiology of palmitic acid (PA) induced insulin resistance (IR) is complex for which two mechanisms are proposed namely ROS induced JNK activation and lipid induced protein kinase-C (PKCε) activation. However, whether these mechanisms act alone or in consortium is not clear.

METHODS AND RESULTS

In this study, we have characterized PA induced IR in liver cells. These cells were treated with different concentrations of PA for either 8 or 16 h. Insulin responsiveness of cells treated with PA for 8 h was found to be same as that of control. However, cells treated with PA for 16 h, showed increased glucose output both in the presence and in absence of insulin only at higher concentrations, indicating development of IR. In these, both JNK and PKCε were activated in response to increased ROS and lipid accumulation, respectively. Activated JNK and PKCε phosphorylated IRS1 at Ser-307 resulting in inhibition of AKT which in turn inactivated GSK3β, leading to reduced glycogen synthase activity. Inhibition of AKT also reduced insulin suppression of hepatic gluconeogenesis by activating Forkhead box protein O1 (FOXO1) and increased expression of the gluconeogenic enzymes and their transcription factors.

CONCLUSION

Thus, our data clearly demonstrate that both these mechanisms work simultaneously and more importantly, identified a threshold of HepG2 cells, which when crossed led to the pathological state of IR in response to PA.

Evaluation of HbA1c from CGM traces in an Indian population

Introduction

The development of continuous glucose monitoring (CGM) over the last decade has provided access to many consecutive glucose concentration measurements from patients. A standard method for estimating glycated hemoglobin (HbA1c), already established in the literature, is based on its relationship with the average blood glucose concentration (aBG). We showed that the estimates obtained using the standard method were not sufficiently reliable for an Indian population and suggested two new methods for estimating HbA1c.

Methods

Two datasets providing a total of 128 CGM and their corresponding HbA1c levels were received from two centers: Health Centre, Savitribai Phule Pune University, Pune and Joshi Hospital, Pune, from patients already diagnosed with diabetes, non-diabetes, and pre-diabetes. We filtered 112 data-sufficient CGM traces, of which 80 traces were used to construct two models using linear regression. The first model estimates HbA1c directly from the average interstitial fluid glucose concentration (aISF) of the CGM trace and the second model proceeds in two steps: first, aISF is scaled to aBG, and then aBG is converted to HbA1c via the Nathan model. Our models were tested on the remaining 32 data- sufficient traces. We also provided 95% confidence and prediction intervals for HbA1c estimates.

Results

The direct model (first model) for estimating HbA1c was HbA1cmmol/mol = 0.319 × aISFmg/dL + 16.73 and the adapted Nathan model (second model) for estimating HbA1c is HbA1cmmol/dL = 0.38 × (1.17 × ISFmg/dL) - 5.60.

Discussion

Our results show that the new equations are likely to provide better estimates of HbA1c levels than the standard model at the population level, which is especially suited for clinical epidemiology in Indian populations.

Genetic polymorphisms in Nrf2 and FoxO1: implications for antioxidant enzyme activity in diabetes

In diabetes, persistent hyperglycemia generates excess reactive oxygen species (ROS), leading to oxidative stress (OS). In response to OS, transcription factors (TFs) Nrf2 and FoxO1 get activated, which induce the expression of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). It is well documented that the antioxidant response in diabetic individuals is very low. Since Nrf2 and FoxO1 are the major TFs activating these genes, we were interested in determining if single nucleotide polymorphisms (SNPs) in genes for these TFs have any association with lowered antioxidant enzyme activity in diabetic individuals. The activity of CAT and SOD and total antioxidant capacity (TAC) were quantified from the serum samples of diabetic (n = 98) and non-diabetic (n = 90) individuals. Genomic DNA was isolated, and Nrf2 and FoxO1 were amplified and sequenced by Illumina NextSeq500. Data were screened for SNPs in amplified regions. An independent samples t-test to find an association between CAT, SOD, and TAC and allele frequency of SNP with the diabetic condition was carried out. We found decreased CAT and SOD activity and significantly low TAC in diabetic individuals. Thirty-two and thirty-four SNPs and Single-nucleotide variants (SNVs) were observed in Nrf2 and FoxO1, respectively. However, a statistically significant difference in the allele frequency distribution between study groups was observed only in two intronic SNPs, rs17524059:A > C and rs60373589:Indel(A) of Nrf2 and FoxO1, respectively. SNPs, rs17524059 in the Nrf2 and rs60373589 of FoxO1, were not associated with reduced CAT and SOD activity and level of TAC in Indian diabetic individuals.Communicated by Ramaswamy H. Sarma.

Andrographolide and pterostilbene inhibit adipocyte differentiation by downregulating PPARγ through different regulators

Adipogenesis involves commitment of stem cells and their differentiation into mature adipocytes. It is tightly regulated by hormones, nutrients and adipokines. Many natural compounds are being tested for their anti-adipogenic activity which can be attributed to apoptosis induction in adipocytes, blocking adipocyte differentiation, or inhibiting intracellular triglyceride synthesis and accumulation. In this study, we have determined molecular mechanism of two phytocompounds: andrographolide (AN) and pterostilbene (PT) during differentiation of the human MSCs into adipocyte. Interestingly, AN upregulates miR27a, whereas, PT upregulated SIRT1 which inhibits the expression of PPARγ. Thus, our results clearly demonstrate that both AN and PT inhibited adipogenesis by blocking a surge of reactive oxygen species (ROS) during differentiation and inhibiting expression of crucial transcription factors like SREBP1c and PPARγ.

Pune GSH supplementation study: Analyzing longitudinal changes in type 2 diabetic patients using linear mixed-effects models

Oral GSH supplementation along with antidiabetic treatment was shown to restore the body stores of GSH significantly and reduce oxidative DNA damage (8-OHdG) in Indian Type 2 diabetic (T2D) patients over 6 months in our recent clinical study. Post hoc analysis of the data also suggested that elder patients benefit from improved HbA1c and fasting insulin. We modeled longitudinal changes in diabetic individuals using a linear mixed-effects (LME) framework and obtained i) the distribution of individual trajectories with and without GSH supplementation and ii) the overall rates of changes in the different study arms. Serial changes in elder and younger diabetic individuals were also modeled independently to examine differences in their progression. The average linear trajectories obtained from the model explain how biochemical parameters in T2D patients progress over 6 months on GSH supplementation. Model estimates show improvements in erythrocytic GSH of 108 µM per month and a reduction in 8-OHdG at a rate of 18.5 ng/μg DNA per month in T2D patients. GSH replenishes faster in younger people than in the elder. 8-OHdG reduced more rapidly in the elder (24 ng/μg DNA per month) than in younger (12 ng/μg DNA per month) individuals. Interestingly, elder individuals show a substantial reduction in HbA1c (0.1% per month) and increased fasting insulin (0.6 µU/mL per month). Changes in GSH correlate strongly with changes in HbA1c, 8-OHdG, and fasting insulin in the elder cohort. The model estimates strongly suggest it improves the rate of replenishment in erythrocytic GSH stores and reduces oxidative DNA damage. Elder and younger T2D patients respond differently to GSH supplementation: It improves the rate of reduction in HbA1c and increases fasting insulin in elder patients. These model forecasts have clinical implications that aid in personalizing treatment targets for using oral GSH as adjuvant therapy in diabetes.

Polyalanine polymorphism in the signal peptide of Glutathione peroxidase 1 (GPX1) gene & its association with osteoporosis

Background & objectives

Osteoporosis is a systemic skeletal disease, characterized by a low bone mass leading to increased bone fragility and hence, a greater susceptibility to the risk of fracture. Since age-related oxidative stress is one of the factors that has been implicated in developing low bone mineral density (BMD), leading to osteoporosis, this study wanted to explore the expression of antioxidant enzymes in individuals with osteoporosis. The present study focused on mapping polymorphism in an important antioxidant enzyme glutathione peroxidase 1 (GPx1) among osteoporosis and healthy Asian Indians.

Methods

Dual-energy X-ray absorptiometry was used to assess BMD of individuals and was classified into normal (n=96) and osteoporotic (n=88) groups. Biochemical parameters such as vitamin D, total oxidant status (TOS), and GPx1 enzyme activity were estimated from plasma samples of recruited individuals. Quantitative real-time qRT-PCR was carried out using GAPDH as an endogenous control. Genomic DNA was isolated from whole blood, and polymorphisms were evaluated by sequencing.

Results

The BMD was lower in osteoporotic individuals, and further analysis of biochemical parameters indicated significantly low 25-hydroxy vitamin D and GPx1 with higher TOS levels in osteoporotic as compared to healthy individuals. Furthermore, qRT-PCR revealed low expression of GPX1 in osteoporotic individuals. GPX1 sequence analysis of the promoter and two exons revealed the lower frequency of five alanine repeats in the osteoporotic individuals.

Interpretation & conclusions

In this study, the in silico analysis revealed the lower frequency of five alanine repeats in exon 1 of GPX1 and high TOS to be associated with osteoporosis. However, no polymorphism was found in exon 2 of GPX1 among the two study groups.

Randomized Clinical Trial of How Long-Term Glutathione Supplementation Offers Protection from Oxidative Damage and Improves HbA1c in Elderly Type 2 Diabetic Patients

Complications in type 2 diabetes (T2D) arise from hyperglycemia-induced oxidative stress. Here, we examined the effectiveness of supplementation with the endogenous antioxidant glutathione (GSH) during anti-diabetic treatment. A total of 104 non-diabetic and 250 diabetic individuals on anti-diabetic therapy, of either sex and aged between 30 and 78 years, were recruited. A total of 125 diabetic patients were additionally given 500 mg oral GSH supplementation daily for a period of six months. Fasting and PP glucose, insulin, HbA1c, GSH, oxidized glutathione (GSSG), and 8-hydroxy-2-deoxy guanosine (8-OHdG) were measured upon recruitment and after three and six months of supplementation. Statistical significance and effect size were assessed longitudinally across all arms. Blood GSH increased (Cohen’s d = 1.01) and 8-OHdG decreased (Cohen’s d = −1.07) significantly within three months (p < 0.001) in diabetic individuals. A post hoc sub-group analysis showed that HbA1c (Cohen’s d = −0.41; p < 0.05) and fasting insulin levels (Cohen’s d = 0.56; p < 0.05) changed significantly in diabetic individuals above 55 years. GSH supplementation caused a significant increase in blood GSH and helped maintain the baseline HbA1c overall. These results suggest GSH supplementation is of considerable benefit to patients above 55 years, not only supporting decreased glycated hemoglobin (HbA1c) and 8-OHdG but also increasing fasting insulin. The clinical implication of our study is that the oral administration of GSH potentially complements anti-diabetic therapy in achieving better glycemic targets, especially in the elderly population.

Molecular mechanism of anti-adipogenic effect of vitexin in differentiating hMSCs

In this study, we evaluated a detailed molecular mechanism of anti-adipogenic activity of vitexin, apigenin flavone glucoside, present in germinated fenugreek seeds, in differentiating human mesenchymal stem cells (hMSCs). The lipid content of differentiated adipocytes was estimated by ORO staining. Effect on mitotic clonal expansion was checked by cell cycle analysis. Expression of early and terminal adipocyte differentiation markers, anti- and pro-adipogenic transcription factors and signalling intermediates regulating them was evaluated at RNA and protein level. We found vitexin to be non-cytotoxic up to 20 μM at which intracellular lipid accumulation was significantly decreased. Cell cycle analysis suggested that vitexin does not affect mitotic clonal expansion. Expression of early and late differentiation markers, such as CEBPα, CEBPβ, PPARγ, FABP4, perilipin, adiponectin and Glut4 was significantly reduced in the presence of vitexin. Expression of KLF4 and KLF15, positive regulators of PPARγ, was decreased, whereas that of negative regulators, namely KLF2, GATA2, miR20a, miR27a, miR27b, miR128, miR130a, miR130b, miR182 and miR548 increased with vitexin treatment. This effect was mediated by the activation of the AMP-activated protein kinase (AMPK) pathway via the activation of LepR and additionally by inhibiting ROS. Thus, our results showed that vitexin regulates the expression of PPARγ and inhibits adipogenesis of hMSCs at an early stage of differentiation.

miR-3666 inhibits development of hepatic steatosis by negatively regulating PPARγ

AIMS

PPARγ is a crucial transcription factor involved in development of hepatic steatosis, an early stage of NAFLD. PPARγ is tightly regulated through various positive and negative regulators including miRNAs. In this study, we report for the first time miR-3666 as a negative regulator of PPARγ and its involvement in development of hepatic steatosis.

METHODS

Binding of miR-3666 to regulate PPARγ was checked by luciferase assay and was confirmed by mutating PPARγ 3'UTR. Regulation of PPARγ was determined by overexpression of miR-3666 in HepG2 cells. Hepatic steatotic state in HepG2 cells was developed by exposure to excess palmitic acid and expression of PPARγ, miR-3666 and some PPARγ target and non-target genes was checked. Involvement of mir-3666 by regulating PPARγ in hepatic steatosis was also examined in liver of HFD fed mice.

RESULTS

On overexpression of miR-3666, PPARγ expression decreased significantly in a dose-dependent manner in HepG2 cells. Binding of miR-3666 to PPARγ was confirmed as the luciferase activity using pMIR-REPORT with PPARγ 3'UTR decreased in PA treated HepG2 cells overexpressing miR-3666 and remained unchanged when PPARγ 3'UTR was mutated. In PA treated HepG2 cells during development of hepatic steatosis PPARγ was significantly up-regulated concomitant with down-regulation of miR-3666. Overexpression of miR-3666 in these cells decreased the extent of hepatic steatosis. Significant up-regulation of PPARγ and down-regulation of miR-3666 was also observed in liver of HFD fed mice indicating that miR-3666 regulates PPARγ in vivo.

CONCLUSIONS

miR-3666 negatively regulates PPARγ by binding to its 3'UTR during development of hepatic steatosis.

Vitexin alleviates non-alcoholic fatty liver disease by activating AMPK in high fat diet fed mice

Non-alcoholic fatty liver disease (NAFLD) is a most common liver disorder characterized by accumulation of fat in the liver and currently there is no approved treatment for it. Obesity and diabetes being leading cause of NAFLD, compounds having anti-obesity activity and potential to reduce insulin resistance are considered suitable candidate for NAFLD treatment. In this study, we checked effect of vitexin, a naturally occurring flavonoid, on high fat diet (HFD) induced NAFLD in C57BL/6J mice. In presence of vitexin, significant reduction in body and liver weight, triglyceride and cholesterol content in serum and liver was observed. Serum Alanine aminotransferase (ALT) and Aspartate aminotransferase (AST) levels were reduced significantly by vitexin which were elevated in HFD group whereas serum lipase activity remained unchanged. Vitexin suppressed de novo lipogenesis by downregulating expression of Peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein-α (C/EBP-α), sterol regulatory element-binding protein-1c (SREBP-1c), Fatty acid synthase (FAS) and Acetyl-CoA Carboxylase (ACC). Additionally, it also enhanced fatty acid oxidation and lipolysis by upregulating Peroxisome proliferator-activated receptor α (PPAR-α), carnitine palmitoyltransferase-1a (CPT-1a) and Adipose triglyceride lipase (ATGL). Inhibition of lipogenesis and activation of lipolysis and fatty acid oxidation by vitexin was found to be mediated by activation of AMP-activated protein kinase (AMPK). Vitexin also improved insulin signalling by activating insulin receptor substrate-1 (IRS-1) and its downstream target AKT. AMPK activation of vitexin was possibly through binding of vitexin to leptin receptor (LepR) which was confirmed by molecular docking studies and by observed enhanced expression of LepR. Thus, we propose that vitexin alleviates NAFLD by activating AMPK possibly by binding to LepR.

Andrographolide enhances redox status of liver cells by regulating microRNA expression

Andrographis paniculata Nees and its principal compound andrographolide are well known for exerting beneficial effects by modulating signaling pathways in different biological systems. Our earlier studies have demonstrated the ability of andrographolide as well as andrographolide enriched extracts to activate Nrf2/HO-1 pathway through adenosine A_2a receptor. Present study investigated ability of andrographolide to regulate Nrf2 induced antioxidant defense systems by miRNAs using HepG2 cells. Andrographolide strongly induced Nrf2 which in turn modulated enzymes of glutathione and thioredoxin antioxidant systems. It also regulated crucial transcription factors viz. hepatocyte nuclear factor alpha (HNF4A) and tumor suppressor protein 53 (p53). Downregulation of HNF4A by andrographolide led to decrease in miRNAs regulating Heme oxygenase-1 (miR-377) and glutathione cysteine ligase (miR-433). Upregulation of p53 on the other hand led to increase in miRNAs regulating thioredoxin interacting protein (miR-17, miR-224) and glutathione peroxidase (miR-181a). Involvement of p53 and HNF4A in modulation of these miRNAs was confirmed by chromatin immunoprecipitation assay. Overall, the work reveals that andrographolide through modulation of p53 and HNF4A, regulates miRNAs leading to upregulation of HO-1, glutathione and thioredoxin systems. Andrographolide thus, can play a beneficial role in modulating antioxidant defense in oxidative stress induced diseases such as diabetes, ageing etc.

A Minimal Model Approach for Analyzing Continuous Glucose Monitoring in Type 2 Diabetes

Continuous glucose monitoring (CGM), a technique that records blood glucose at a regular intervals. While CGM is more commonly used in type 1 diabetes, it is increasingly becoming attractive for treating type 2 diabetic patients. The time series obtained from a CGM provides a rich picture of the glycemic state of the subjects and may help have tighter control on blood sugar by revealing patterns in their physiological responses to food. However, despite its importance, the biophysical understanding of CGM is far from complete. CGM data series is complex not only because it depends on the composition of the food but also varies with individual physiology. All of these make a full modeling of CGM data a difficult task. Here we propose a simple model to explain CGM data in type 2 diabetes. The model combines a relatively simple glucose-insulin dynamics with a two-compartment food model. Using CGM data of a healthy and a diabetic individual we show that this model can capture liquid meals well. The model also allows us to estimate the parameters in a relatively straightforward manner. This opens up the possibility of personalizing the CGM data. The model also predicts insulin time series from the model, and the rate of appearance of glucose due to food. Our methodology thus paves the way for novel analyses of CGM which have not been possible before.

UV induced foot duplication in regenerating hydra is mediated by metalloproteinases and modulation of the Wnt pathway

We have shown earlier that irradiation with UV induces duplication of foot in regenerating middle pieces of hydra. The present study was undertaken to elucidate the underlying mechanism(s) leading to this curious phenomenon. UV irradiation induced duplicated foot in about 30% of regenerating middle pieces. Metalloproteinases are important in foot formation, while Wnt pathway genes are important in head formation in hydra. The effect of UV irradiation on expression of these genes was studied by in situ hybridization and q-PCR. In whole polyps and middle pieces, UV irradiation led to up-regulation of HMP2 and HMMP, the two metalloproteinases involved in foot formation in hydra. HMP2 expression was significantly increased starting from 30 min post exposure to UV at 254 nm (500 J/m(2)), while HMMP showed significant up-regulation 6 h post UV exposure onwards. In middle pieces, increased expression of both metalloproteinases was observed only at 48 h. In whole polyps as well as in middle pieces, expression of Wnt3 and β-catenin was detected within 30 min of UV exposure and was accompanied by up-regulation of GSK3β, DKK3 and DKK1/2/4, inhibitors of the Wnt pathway. These conditions likely lead to inactivation of Wnt signaling. We therefore conclude that duplication of foot due to UV irradiation in regenerating middle pieces of hydra is a combined effect of up-regulation of metalloproteinases and inactivation of the Wnt pathway. Our results suggest that UV irradiation can be employed as a tool to understand patterning mechanisms during foot formation in hydra.

Superoxide Dismutase 2 Polymorphisms and Osteoporosis in Asian Indians: A Genetic Association Analysis

Oxidative stress plays an important role in the development of osteoporosis. The present cross-sectional study focuses on mapping single nucleotide polymorphisms (SNPs) in the mitochondrial manganese superoxide dismutase (SOD2) gene in Asian Indians. The bone mineral density (BMD) of study subjects was assessed by dual x-ray absorptiometry. Individuals were classified as normal (n = 82) or osteoporotic (n = 98). Biochemical parameters such as vitamin D, total oxidant status (TOS) and SOD2 enzyme activity were estimated from plasma samples. Semi-quantitative PCR was carried out using GAPDH as an endogenous control. Genomic DNA was isolated from whole blood and SNPs were evaluated by PCR sequencing. Thirteen SNPs are reported in the examined region of the SOD2 gene, out of which in our samples SNPs rs5746094 and rs4880 were found to be polymorphic. Allele G of rs5746094 (intronic) and allele C of rs4880 (exonic) are significantly higher in the osteoporotic individuals. Presence of allele C of rs4880 and increased level of TOS among osteoporotic individuals were found to be associated with disease risk.

Molecular Characterization and Meta-Analysis of Gut Microbial Communities Illustrate Enrichment of Prevotella and Megasphaera in Indian Subjects

The gut microbiome has varied impact on the wellbeing of humans. It is influenced by different factors such as age, dietary habits, socio-economic status, geographic location, and genetic makeup of individuals. For devising microbiome-based therapies, it is crucial to identify population specific features of the gut microbiome. Indian population is one of the most ethnically, culturally, and geographically diverse, but the gut microbiome features remain largely unknown. The present study describes gut microbial communities of healthy Indian subjects and compares it with the microbiota from other populations. Based on large differences in alpha diversity indices, abundance of 11 bacterial phyla and individual specific OTUs, we report inter-individual variations in gut microbial communities of these subjects. While the gut microbiome of Indians is different from that of Americans, it shared high similarity to individuals from the Indian subcontinent i.e., Bangladeshi. Distinctive feature of Indian gut microbiota is the predominance of genus Prevotella and Megasphaera. Further, when compared with other non-human primates, it appears that Indians share more OTUs with omnivorous mammals. Our metagenomic imputation indicates higher potential for glycan biosynthesis and xenobiotic metabolism in these subjects. Our study indicates urgent need of identification of population specific microbiome biomarkers of Indian subpopulations to have more holistic view of the Indian gut microbiome and its health implications.

Mathematical Modeling of Glutathione Status in Type 2 Diabetics with Vitamin B12 Deficiency

Deficiencies in vitamin B12 and glutathione (GSH) are associated with a number of diseases including type 2 diabetes mellitus. We tested newly diagnosed Indian diabetic patients for correlation between their vitamin B12 and GSH, and found it to be weak. Here we seek to examine the theoretical dependence of GSH on vitamin B12 with a mathematical model of 1-carbon metabolism due to Reed and co-workers. We study the methionine cycle of the Reed-Nijhout model by developing a simple "stylized model" that captures its essential topology and whose kinetics are analytically tractable. The analysis shows-somewhat counter-intuitively-that the flux responsible for the homeostasis of homocysteine is, in fact, peripheral to the methionine cycle. Elevation of homocysteine arises from reduced activity of methionine synthase, a vitamin B12-dependent enzyme, however, this does not increase GSH biosynthesis. The model suggests that the lack of vitamin B12-GSH correlation is explained by suppression of activity in the trans-sulfuration pathway that limits the synthesis of cysteine and GSH from homocysteine. We hypothesize this "cysteine-block" is an essential consequence of vitamin B12 deficiency. It can be clinically relevant to appreciate that these secondary effects of vitamin B12 deficiency could be central to its pathophysiology.

Norepinephrine-induced apoptotic and hypertrophic responses in H9c2 cardiac myoblasts are characterized by different repertoire of reactive oxygen species generation

Despite recent advances, the role of ROS in mediating hypertrophic and apoptotic responses in cardiac myocytes elicited by norepinephrine (NE) is rather poorly understood. We demonstrate through our experiments that H9c2 cardiac myoblasts treated with 2 µM NE (hypertrophic dose) generate DCFH-DA positive ROS only for 2 h; while those treated with 100 µM NE (apoptotic dose) sustains generation for 48 h, followed by apoptosis. Though the levels of DCFH fluorescence were comparable at early time points in the two treatment sets, its quenching by DPI, catalase and MnTmPyP suggested the existence of a different repertoire of ROS. Both doses of NE also induced moderate levels of H₂O₂ but with different kinetics. Sustained but intermittent generation of highly reactive species detectable by HPF was seen in both treatment sets but no peroxynitrite was generated in either conditions. Sustained generation of hydroxyl radicals with no appreciable differences were noticed in both treatment sets. Nevertheless, despite similar profile of ROS generation between the two conditions, extensive DNA damage as evident from the increase in 8-OH-dG content, formation of γ-H2AX and PARP cleavage was seen only in cells treated with the higher dose of NE. We therefore conclude that hypertrophic and apoptotic doses of NE generate distinct but comparable repertoire of ROS/RNS leading to two very distinct downstream responses.

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H9c2 myoblasts upon treatment with 2 and 100 µM NE induces hypertrophy and apoptosis.

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Both treatments show comparable levels of DCFH fluorescence with different kinetics.

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Both treatments show comparable levels of HPF fluorescence in an oscillating manner.

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More hydroxyl radical was generated in 100 µM NE treated set.

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DNA damage and apoptosis occurs only in 100 µM NE treated sets.

The relationship between fasting plasma glucose and HbA1c during intensive periods of glucose control in antidiabetic therapy

OBJECTIVE

HbA1c measurements are typically less variable than fasting plasma glucose (FPG) for diagnosing diabetes, and for assessment of progress on glucose control therapy. However HbA1c reaches steady-state relative to average plasma glucose over about 120 days. HbA1c thus overestimates average FPG during first three months of starting therapy in newly diagnosed diabetic patients, and care needs to be exercised in interpreting HbA1c measurements during this period. At steady-state excellent regression exists between HbA1c and FPG. We hypothesize that this regression can also be used to obtain reliable estimates of HbA1c relative to FPG at 4 and 8 weeks following the onset of therapy.

MATERIALS AND METHODS

We collected FPG and HbA1c data of type 2 diabetic patients over the first 8 weeks of starting antidiabetic treatment. We fit linear and nonlinear regression models to steady-state data, and estimated how much measured HbA1c deviates at 4 and 8 weeks from these theoretical relations.

RESULTS

If measured HbA1c is decremented by 0.7% (8 mmol/mol) at 4 weeks and 0.3% (3 mmol/mol) at 8 weeks, this corrected HbA1c is a better predictor of the corresponding FPG. Using hyperbolic regression, corrections to HbA1c are 0.5 and 0.1% (5 and 1 mmol/mol), respectively.

CONCLUSION

With the corrections proposed here, HbA1c measurements can be better interpreted in the early weeks of antidiabetic treatment.

Thresholds of oxidative stress in newly diagnosed diabetic patients on intensive glucose-control therapy

Cellular and animal studies suggest that oxidative stress could be the central defect underlying both beta-cell dysfunction and insulin resistance in type 2 diabetes mellitus. A reduction of glycemic stress in diabetic patients on therapy alleviates systemic oxidative stress and improves insulin resistance and beta-cell secretion. Monitoring oxidative stress systematically with glucose can potentially identify an individual's recovery trajectory. To determine a quantitative model of serial changes in oxidative stress, as measured via the antioxidant glutathione, we followed patients newly diagnosed with diabetes over 8 weeks of starting anti-diabetic treatment. We developed a mathematical model which shows recovery is marked with a quantal response. For each individual the model predicts three theoretical quantities: an estimate of maximal glutathione at low stress, a glucose threshold for half-maximal glutathione, and a rate at which recovery progresses. Individual patients are seen to vary considerably in their response to glucose control. Thus, model estimates can potentially be used to determine whether an individual patient's response is better or worse than average in terms of each of these indices; they can therefore be useful in reassessing treatment strategy. We hypothesize that this method can aid the personalization of effective targets of glucose control in anti-diabetic therapy.

Conservation of the nucleotide excision repair pathway: characterization of hydra Xeroderma Pigmentosum group F homolog

Hydra, one of the earliest metazoans with tissue grade organization and nervous system, is an animal with a remarkable regeneration capacity and shows no signs of organismal aging. We have for the first time identified genes of the nucleotide excision repair (NER) pathway from hydra. Here we report cloning and characterization of hydra homolog of xeroderma pigmentosum group F (XPF) gene that encodes a structure-specific 5' endonuclease which is a crucial component of NER. In silico analysis shows that hydra XPF amino acid sequence is very similar to its counterparts from other animals, especially vertebrates, and shows all features essential for its function. By in situ hybridization, we show that hydra XPF is expressed prominently in the multipotent stem cell niche in the central region of the body column. Ectoderm of the diploblastic hydra was shown to express higher levels of XPF as compared to the endoderm by semi-quantitative RT-PCR. Semi-quantitative RT-PCR analysis also demonstrated that interstitial cells, a multipotent and rapidly cycling stem cell lineage of hydra, express higher levels of XPF mRNA than other cell types. Our data show that XPF and by extension, the NER pathway is highly conserved during evolution. The prominent expression of an NER gene in interstitial cells may have implications for the lack of senescence in hydra.

Immunohistochemical localization and biochemical changes in catalase and superoxide dismutase during metamorphosis in the olfactory system of frog Microhyla ornata

Amphibian metamorphosis is characterized by rapid tissue remodeling and drastic changes in the body structure and function. Like other organs, olfactory system also undergoes a dramatic rearrangement as the animal experiences transition from aquatic to terrestrial habitat. Reactive oxygen species (ROS) are known to play an important role during anuran metamorphosis and role of antioxidant enzymes like catalase and superoxide dismutase (SOD) are believed to play a major role in these processes. Therefore, we hypothesize that antioxidant enzymes in the olfactory system may undergo changes that reflect metamorphic processes. Immunohistochemical study revealed the presence of catalase and SOD in the olfactory receptor neurons and also granular reaction in olfactory epithelium of medial diverticulum during metamorphosis. Catalase and SOD immunoreactivity were seen in the epithelium of lateral diverticulum, vomeronasal organ as metamorphosis proceeds and in the apical lining of olfactory epithelium of adult frog. Biochemical study showed that catalase activity gradually increases in the olfactory system from metamorphic stage 40-46 and adult, while SOD activity decreases from stage 40 to 46 and increases in adult. Thus, the localization and relative levels of catalase and SOD during metamorphosis in the olfactory system suggests that these enzymes may be involved in protection from oxidative damage.

Indian herbs and herbal drugs used for the treatment of diabetes

Traditional Medicines derived from medicinal plants are used by about 60% of the world’s population. This review focuses on Indian Herbal drugs and plants used in the treatment of diabetes, especially in India. Diabetes is an important human ailment afflicting many from various walks of life in different countries. In India it is proving to be a major health problem, especially in the urban areas. Though there are various approaches to reduce the ill effects of diabetes and its secondary complications, herbal formulations are preferred due to lesser side effects and low cost. A list of medicinal plants with proven antidiabetic and related beneficial effects and of herbal drugs used in treatment of diabetes is compiled. These include, Allium sativum, Eugenia jambolana, Momordica charantia Ocimum sanctum, Phyllanthus amarus, Pterocarpus marsupium, Tinospora cordifolia, Trigonella foenum graecum and Withania somnifera. One of the etiologic factors implicated in the development of diabetes and its complications is the damage induced by free radicals and hence an antidiabetic compound with antioxidant properties would be more beneficial. Therefore information on antioxidant effects of these medicinal plants is also included.

Antioxidant properties of germinated fenugreek seeds

Fenugreek (Trigonella foenum-graecum) is used as a spice, vegetable and a medicinal plant. Since antioxidant properties have been linked to health benefits of natural products, such properties were studied in germinated fenugreek seeds which are considered to be more beneficial than dried seeds. Different fractions of the germinated seeds were used to determine their antioxidant potential at different levels. The assays employed were ferric reducing antioxidant power, radical scavenging by 1,1-diphenyl-2-picrylhydrazyl, ferrylmyoglobin/2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid, pulse radiolysis, oxygen radical absorbance capacity and inhibition of lipid peroxidation in mitochondrial preparations from rat liver. An aqueous fraction of fenugreek exhibited the highest antioxidant activity compared with other fractions. As the quantity of phenolic and flavonoid compounds can be related to antioxidant activity, the contents from these extracts were measured. HPLC analysis was carried out to detect polyphenols, flavonoids and other components. This study reveals significant antioxidant activity in germinated fenugreek seeds which may be due partly to the presence of flavonoids and polyphenols.

Protection of liver cells from ethanol cytotoxicity by curcumin in liver slice culture in vitro

Curcumin, a widely used spice and colouring agent in food has been shown to have a broad spectrum of biological activities such as anti-inflammatory, anti-neoplastic, antimutagenic and antioxidant. We have used liver slice culture model to demonstrate hepatoprotective activity of curcumin in vitro. Ethanol has been used as a hepatotoxin and the cytotoxicity of ethanol is estimated by quantitating the release of LDH. Ethanol induces 3.5 times more release of LDH from the liver cells and twice the amount of lipid peroxidation as compared to the cells from untreated liver tissue and this was significantly reduced in presence of curcumin (5 microM). We measured the activity of antioxidant enzymes (AOEs) namely superoxide dismutase, catalase and peroxidase and found that in ethanol treated cells activity of all three enzymes was elevated. However, when curcumin was added along with ethanol their levels were kept low. The fact that release of LDH is significantly reduced along with lipid peroxidation and the activity of AOEs is kept low indicates that curcumin by its antioxidant activity reduced the oxidative stress induced by ethanol and protected the liver cells in vitro.

FGF signaling is essential for the early events in the development of the chick nervous system and mesoderm

Fibroblast growth factor (FGF) belongs to a family of polypeptides with diverse biological functions. In the present study we have assessed the role of FGF signaling in the development of nervous system and mesodermal tissues in chick embryo. Treatment of in vitro cultured embryos with exogenous, human recombinant FGF led to abnormalities in neural induction and development, notochord formation and somitogenesis as studied by gross morphology and histology. Overall growth and development was also adversely affected as seen from the measurement of body axis length. Further, treatment of embryos with FGF resulted in differential modulation of expression of two genes important in normal development as studied by whole mount in situ hybridization using DIG-labeled riboprobes. The expression of Brachyury, which is necessary for mesoderm formation, was down-regulated in FGF-treated embryos. The expression of noggin, the product which participates in the patterning of the chick neural tube was, on the other hand, up-regulated within 2 h. We also studied development of neural and mesodermal tissues in conditions where FGF signaling was defective. This was achieved by culturing the embryos in the presence of suramin. In the presence of low doses of suramin (100-150 nmole/culture), abnormalities were detected mainly in the mesodermal structures while at higher doses (200-400 nmole/culture), the nervous system too was found to be abnormal in a large proportion of embryos. Treatment of chick embryos with suramin (200 nmole/culture) also modulated the expression of Brachyuryand noggin within a 2 h period. The results showthat FGF signaling plays an important role in the molecular events leading to the development of nervous system and mesodermal tissues in the chick embryo.

Activin disrupts somitogenesis in cultured chick embryos

The anatomical and cell biological aspects of somite formation in the chick embryo have been rather well studied. Molecular regulation of somitogenesis in vertebrates is just beginning to be understood. We have studied the effects of human recombinant activin on somitogenesis in gastrulating chick embryos cultured in vitro with a view to assessing the possible role of activin-related molecules in this phenomenon. Activin disrupted somitogenesis in treated embryos, resulting in the formation of abnormal, split or ectopic somites. Light microscopic examination indicated that the ability of activin to interfere with somitogenesis might be partly due to initiation of somite formation at ectopic sites. We show that these cells are indeed somitogenic by their expression of one of the earliest somite-specific marker genes, Pax3. Scanning electron microscopic examination of control and treated embryos revealed direct effects of activin on cell-cell interactions. Cells from treated embryos exhibited disrupted intercellular adhesion leading to large intercellular spaces, altered cell shapes and modification of cell surface protrusions. The effects of activin on somitogenesis appear to be specific, since the neural structures, which are generally more susceptible to chemical insults during gastrulation, were relatively less affected. The results clearly point to a role of activin-related molecules in somitogenesis in the chick embryo.

Hydra constitutively expresses transcripts involved in vertebrate neural differentiation

The diploblastic Hydra is among the most primitive multicellular organisms. Using cross-hybridization with Xenopus probes, noggin-like transcripts were detected in the hypostome and basal disc of adult Hydra (Pelmatohydra oligactis), regions with properties similar to that of the amphibian organizer. This points to the possibility of a close molecular similarity between the Xenopus and Hydra organizers. The constitutive expression of a noggin-like gene in Hydra may be responsible for its regenerative capacity.

Reproductive toxicity of piperine in Swiss albino mice

Piperine (CAS 94-62-2) is a constituent of various spices which are used as common food additives all over the world. The reproductive toxicity of piperine was studied in Swiss albino mice. Relevant short-term tests were employed to assess the effect on estrous cycle, mating behaviour, toxicity to male germ cells, fertilization, implantation and growth of pups. Piperine (10 and 20 mg/kg b.w.) increased the period of the diestrous phase which seemed to result in decreased mating performance and fertility. Post-partum litter growth was not affected by the piperine treatment. Sperm shape abnormalities were not induced by piperine at doses up to 75 mg/kg b.w. Considerable anti-implantation activity was recorded after five days post-mating oral treatment with piperine. The sex ratio and post-implantation loss were unaffected after treatment with piperine. Intrauterine injection of piperine caused the total absence of implants in either of the uterine horns (16.66%) or one of the horns (33%) of treated females. No histopathological changes were detected in the ovary and the uterus at the cellular level. Prostaglandin E1-induced acute inflammation of rat paw was significantly reduced after piperine treatment. Our results show that piperine interferes with several crucial reproductive events in a mammalian model.

Assessment of genotoxic effect of piperine using Salmonella typhimurium and somatic and somatic and germ cells of Swiss albino mice

Piperine (CAS 94-62-2) is a constituent of various spices and is used as a common food additive all over the world. The genotoxic potential of piperine was assessed using four different test systems, namely, Ames test using Salmonella typhimurium, micronucleus test, sperm shape abnormality test and dominant lethal test using Swiss albino mice. In the Ames test, six different doses of piperine, in the range of 0.005-10 mumol/plate, did not induce his+ revertants, with or without metabolic activation, indicating its nonmutagenic nature. In the bone narrow micronucleus test using two doses in the range of therapeutic usage (10 and 20 mg/kg body weight), piperine itself was non-mutagenic. Like in somatic cells, piperine (10 and 50 mg/kg body weight) failed to induce mutations in male germ cells of mouse as assessed by using the sperm shape abnormality and dominant lethal tests. Piperine thus appears to be a non-genotoxic chemical.

Cell surface alterations by taxol associated with abnormal morphogenesis in the chick embryo

The anticancer drug taxol brings about its biological effects by altering the stability of microtubules. We have examined the effects of taxol on early morphogenesis in chick embryos cultured in vitro. Taxol induced various abnormalities in the developing nervous system, heart and somites as well as general retardation of development. SEM studies revealed that taxol treatment leads to dramatic alterations in the embryonic cell surfaces. Time-course experiments demonstrated that the action of taxol is very rapid and becomes evident within a few minutes at the ultrastructural level. Taxol thus throws embryonic cell adhesion and motility out of balance. This appears to be the major cause of abnormal morphogenesis in taxol-treated embryos.

Ultrastructural cell surface alterations in developing embryos of frog (Microhyla ornata) treated with cytochalasins

Scanning electron microscopic examination of M. ornata embryos treated with cytochalasins A, B and H (CA, CB and CH) showed extensive cell disaggregation resulting in large intercellular spaces and apparent loss of intercellular communication. All the three cytochalasins significantly reduced surface features, such as, filopodia and membrane ruffling which are considered essential for normal morphogenetic movements. Appreciable qualitative differences could not be detected in effects exerted by CA, CB and CH although potency of the three drugs clearly differed. The results demonstrate that in spite of the differences in their primary mechanisms of action, treatment with all the three cytochalasins culminates in comparable effects on the cell surface architecture resulting into abnormal morphogenesis.

Mesoderm enhancing effect of human seminal plasma inhibin and its synthetic C-terminal nonapeptide fragment in the chick embryo

Isomers of fibroblast growth factor and members of the transforming growth factor beta family have been identified as potent mesoderm inducing factors, particularly in amphibians. Activins belonging to the latter group are capable of inducing all types of mesoderm. Inhibins, also belonging to the same family of proteins have an exactly opposite biological action than activins in the adult organism. We have examined the effects of human seminal plasma inhibin on the early development of the chick embryo, where also activins appear to be important in mesoderm induction. Contrary to expectations, inhibin brought about stimulation of development of somites and heart, structures of mesodermal origin, and increase in the body length in more than 50% of the treated chick blastoderms. A synthetic fragment of human seminal plasma inhibin, a nonapeptide fragment of C-terminal end, also exhibited similar effects. In some cases the treatments resulted in completely abnormal development while in some increase in the number of somites was associated with abnormality in the anterior region. Our results demonstrate that human seminal plasma inhibin does not act as an inhibitor of mesoderm induction in the chick embryo but in amniotes inhibin-related molecules may have a role as mesoderm enhancers.

Genotoxicity assessment of the antifungal antibiotic aureofungin in Salmonella typhimurium and Swiss albino mice

The widely used agricultural antifungal agent aureofungin (ARF) was subjected to genotoxicity assessment using the Ames Salmonella assay as well as the in vivo micronucleus test and dominant lethal test in Swiss mice. In the Ames Salmonella spot test, ARF slightly elevated the number of histidine revertants after metabolic activation over a wide dose range (1-1000 micrograms/plate) in TA102 but not in TA97a, TA98 or TA100. In the preincubation plate incorporation assay with TA102, ARF increased the number of revertants in a dose-dependent manner only after metabolic activation. ARF failed to significantly elevate the frequency of micronucleated polychromatic erythrocytes (PE) in the bone marrow of Swiss mice. It elevated the frequency of dominant lethal mutations in the 7th and 8th weeks at 30 mg/kg body weight, a concentration much higher than the actual concentration used in the field. We conclude that ARF is non-mutagenic in somatic cells in vivo at doses used in the present study, probably mutagenic in stem-cell spermatogonia and may be classified as an equivocal promutagen, possibly acting as a cross-linker.

Essential role of insulin during early prepancreatic development of the frog Microhyla ornata

We undertook the present study to examine the role of insulin during early development of frog when functional pancreas does not exist. Two approaches were adopted to achieve this objective. In the first approach, influence of exogenous insulin on the early embryonic development of the frog Microhyla ornata was studied. In the second approach, the effects of antiserum to insulin on embryonic development were studied. Exogenous insulin stimulated the embryonic development while immunoneutralization of endogenous insulin not only resulted in retardation of development but also induced developmental abnormalities. These results demonstrate the essential role of insulin during early embryonic development of this frog. To our knowledge, such findings have not been reported so far in any amphibian.

Modulation of cyclophosphamide mutagenicity by vitamin C in the in vivo rodent micronucleus assay

The modulatory effect of vitamin C (Vit C) on the mutagenic effect of the antineoplastic drug cyclophosphamide (CP) was assessed in the in vivo micronucleus test in Swiss mice. Simultaneous oral administration of Vit C with i.p. administration of CP was found to decrease the frequency of micronucleated polychromatic erythrocytes elevated by CP. Vit C exhibited a significant antimutagenic effect over a wide dose range (1.56-200 mg/kg). The dose-response relationship was highly significant. These results demonstrated the ability of the in vivo micronucleus test to detect in vivo modulation of CP mutagenicity by Vit C. Our earlier results and those from other laboratories also indicate that this model system is suitable for primary in vivo screening of modulation of mutagenesis.

Studies on modulation of the effects of colchicine by L-cysteine using bone marrow of Swiss mice

Colchicine (COL) elevates the frequency of micronucleated polychromatic erythrocytes (PE), the ratio of normochromatic to polychromatic erythrocytes (N/PE) and the frequency of large PE due to spindle disruption. Simultaneous i.p. injection of L-cysteine (CYS) does not influence the effects of COL while if administered 1 h prior to COL, CYS suppresses the N/PE ratio and frequency of large PE but not the frequency of micronucleated PE elevated by COL. Preincubation of CYS with COL at 37 degrees C for 1 h results in a significant decrease in all the COL effects. The modulatory effect of exogenous CYS appears to be due to its competition with the endogenous tubulin cysteine residues for interacting with COL.

In vivo antimutagenic effect of ascorbic acid against mutagenicity of the common antiamebic drug diiodohydroxyquinoline

We have previously shown that the common antiamebic drug diiodohydroxyquinoline (DIHQ) exhibits mutagenic activity in the in vivo micronucleus test in Swiss albino mice. Results of experiments undertaken to study the influence of ascorbic acid (vitamin C) on the mutagenicity of DIHQ in this model system showed that ascorbic acid acts as an antimutagen against DIHQ. The effective antimutagenic doses of ascorbic acid themselves do not show any genotoxic effects in this in vivo system. It will be necessary, however, to elucidate the mechanism of action of ascorbic acid as well as its effects on the therapeutic properties of DIHQ before a practical use of ascorbic acid is contemplated for this purpose.

Bio-antimutagenic effect of L-cysteine on diiodohydroxyquinoline-induced micronuclei in Swiss mice

The mutagenic potential of diiodohydroxyquinoline (DIHQ), a common anti-amebic drug, was tested using the in vivo micronucleus test in Swiss mice following oral administration. It was found to be mutagenic in a dose-dependent manner. Using the same model system, the bio-antimutagenic effect of the sulfhydryl compound L-cysteine against DIHQ was established.

Effects of cytochalasin H on chick embryo explants cultured in vitro

Effects of the mould metabolite, cytochalasin H (CH) were studied in chick embryos explanted at stages 4, 5 and 8 and cultured in vitro. Morphological and histological observations revealed that the major effects of CH are inhibition of primary morphogenesis of heart and disaggregation of cells. Inhibition of neural tube closure, microcephaly and shortening of body axis was also noted. The effects were found to be dose- and stage-dependent. Histochemical studies demonstrated that CH brings about a reduction in the contents of glycoproteins and non-sulfated glycosaminoglycans important in cell adhesion. Effects of CH appeared due to its interference primarily with cell adhesion and secondarily with morphogenetic movements.

Inhibitory effect of cytochalasin H on cell reaggregation of the fresh water sponge, Ephydatia meyeni Carter

Cytochalasin H (CH) has been shown to inhibit the reaggregation of dissociated cells of a fresh water sponge. The effect is dose-dependent and reversible. Even after 24 h of CH treatment, the cells show the formation of pseudopodia suggesting that the effect of CH may not be due to arrested cell motility. Exogenously added alpha-D-glucosamine, a precursor of complex carbohydrates, brings about reaggregation of CH-treated cells. Fluorescent Con A binding, both patching and capping, is shown by untreated as well as CH-treated cells. It is likely that CH, like cytochalasin B, may interfere with the production, release or binding of carbohydrate-containing macromolecules important in cell aggregation.