Altered intestinal microbiota in patients with chronic pancreatitis: implications in diabetes and metabolic abnormalities.

Intestinal dysbiosis and its functional implications in chronic pancreatitis (CP) have not been elaborately studied. We evaluated the taxonomic and functional alterations in intestinal microbiota in 30 well-characterised patients with CP (16 without, 14 with diabetes) and 10 healthy controls. The patients with CP and diabetes had significantly longer disease duration and greater degree of malnutrition. There was increase in plasma endotoxin concentrations from controls to CP non-diabetics to CP diabetics. We observed significant differences in richness and alpha diversity between the groups. We also observed increase in the Firmicutes:Bacteroidetes ratio in CP patients without and with diabetes. There was reduction in abundance of Faecalibacterium prausnitzii and Ruminococcus bromii from controls to CP non-diabetics to CP diabetics. On the other hand, there was increase in LPS (endotoxin) synthetic pathways (KEGG orthology) in the groups. Faecalibacterium prausnitzii abundance correlated negatively with plasma endotoxin and glycemic status; while plasma endotoxin correlated positively with blood glucose and negatively with plasma insulin. Our results have important implications for future studies exploring mechanistic insights on secondary diabetes in CP.

Pancreatic stellate cell: Pandora's box for pancreatic disease biology.

Pancreatic stellate cells (PSCs) were identified in the early 1980s, but received much attention after 1998 when the methods to isolate and culture them from murine and human sources were developed. PSCs contribute to a small proportion of all pancreatic cells under physiological condition, but are essential for maintaining the normal pancreatic architecture. Quiescent PSCs are characterized by the presence of vitamin A laden lipid droplets. Upon PSC activation, these perinuclear lipid droplets disappear from the cytosol, attain a myofibroblast like phenotype and expresses the activation marker, alpha smooth muscle actin. PSCs maintain their activated phenotype via an autocrine loop involving different cytokines and contribute to progressive fibrosis in chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC). Several pathways (e.g., JAK-STAT, Smad, Wnt signaling, Hedgehog etc.), transcription factors and miRNAs have been implicated in the inflammatory and profibrogenic function of PSCs. The role of PSCs goes much beyond fibrosis/desmoplasia in PDAC. It is now shown that PSCs are involved in significant crosstalk between the pancreatic cancer cells and the cancer stroma. These interactions result in tumour progression, metastasis, tumour hypoxia, immune evasion and drug resistance. This is the rationale for therapeutic preclinical and clinical trials that have targeted PSCs and the cancer stroma.

Polymorphisms in UGT1A1 Gene Predispose South Indians to Pigmentous Gallstones.

BACKGROUND/OBJECTIVES: Pigmentous gallstones occur in South Indians despite significant higher levels of circulating cholesterol. This study was conducted to identify the biochemical and/or genetic causes for the formation of pigmentous gallstones in this ethnic group. METHODS: Plasma lipid profile, bile cholesterol, acids, and phospholipid levels were estimated in patients with gall stone disease and age, sex matched controls using standard protocols. Twenty-seven SNPs related to cholesterol and bilirubin metabolism pathway genes were genotyped in the study population using the Sequenom platform. An equilibrium phase diagram involving bile salt-phospholipid-cholesterol was generated to relate phenotype with the genotype. RESULTS: There were no significant differences in the lipid profiles between the patients (n = 305) and controls (n = 177). Biliary cholesterol, acids, and phospholipids were significantly different between patients and controls. Single locus analysis revealed association of variants in ABCG6, ABCG8, and UGT1A1 genes with the disease; however when correction was applied as multiple testing was done, only one variant (rs6742078) in UGT1A1 gene was found to be associated with gall stone disease. Equilibrium phase diagram suggested that few samples were in the crystal formation zone. The mutant, but not wild type or heterozygous genotype of SNPs (rs6742078 and rs887829) in UGT1A1 gene, was associated with significantly higher levels of bilirubin. CONCLUSIONS: Higher incidence of pigment stones in South Indians could be due to raised serum bilirubin levels that may be ascribed to variant in the UGT1A1 gene involved in glucuronidation of free bilirubin.

Extremely low frequency magnetic fields induce oxidative stress in rat brain.

The present investigation was conducted to understand the influence of long-term exposure of rats to extremely low frequency magnetic fields (ELF-MF), focusing on oxidative stress (OS) on different regions of rat's brain. Male Wistar rats (21-day-old) were exposed to ELF-MF (50 Hz; 50 and 100 µT) for 90 days continuously; hippocampal, cerebellar and cortical regions from rats were analyzed for (i) reactive oxygen species (ROS), (ii) metabolites indicative of OS and (iii) antioxidant enzymes. In comparison to control group rats, the rats that were continuously exposed to ELF-MF caused OS and altered glutathione (GSH/GSSG) levels in dose-dependent manner in all the regions of the brain. Accumulation of ROS, lipid peroxidation end products and activity of superoxide dismutase in different regions was in the descending order of cerebellum < hippocampus < cortex. Decrement in GSH/GSSG levels and increment in glutathione peroxidase activity were in the descending order of hippocampus < cerebellum < cortex. The continuous exposure to ELF-MF caused OS in all the examined regions of brain more significantly at 100 µT than at 50 µT. Varied influences observed in different regions of the brain, as documented in this study, may contribute to altered metabolic patterns in its related regions of the central nervous system, leading to aberrant neuronal functions.

Long-term functions of encapsulated islets grafted in nonhuman primates without immunosuppression.

BACKGROUND: Long-term survival and functions of encapsulated islet grafts need to be evaluated in the absence of immunosuppression. The present study aimed to assess the viability and functions of macroencapsulated islets grafted in nonhuman primates without immunosuppression for 1 year. METHODS: Islet transplantations were performed in partially pancreatectomized rhesus monkeys (two autologous and four allogenic) without immunosuppression using immunoisolatory devices. Macroencapsulated islets were implanted subcutaneously (5000-8000 IEQ/device) at two sites (left thigh and interscapular region) and were explanted at 2, 6, and 12 months after implantation. Staining for viability and apoptosis, in vivo and in vitro glucose-stimulated insulin release, expression of insulin and glucagon genes, and histopathologic examination of the device were used to assess engraftment potential, viability, and functions of islets. Animals were regularly monitored for dietary intake, body weight, and fasting blood glucose levels after islet transplantation. RESULTS: Devices explanted showed vascularization at the end of 2, 6, and 12 months with occasional lymphocytes and minimal fibrosis outside the device. Flow cytometric analysis revealed 97.9%±1.5% and 94.3%±5.71% viable ß cells in interscapular site and thigh in autologous recipients and 85.6%±4.01% (interscapular site) and 74.1%±12.05% (thigh) viable ß cells in allogenic islet recipients. In vivo glucose challenge test revealed significantly increased glucose-stimulated insulin release (P=0.028) in the left thigh with implant (17.58±3.13 mU/L) compared with the thigh without implant (9.86±1.063 mU/L). Insulin and glucagon gene expression was evident in islets recovered from explanted device. CONCLUSIONS: These results indicate that subcutaneous implantation of macroencapsulated islets is minimally invasive and has potential for transplantation without immunosuppression.

Characterization of calcineurin-dependent response element binding protein and its involvement in copper-metallothionein gene expression in Neurospora.

In continuation of our recent observations indicating the presence of a lone calcineurin-dependent response element (CDRE) in the -3730bp upstream region of copper-induced metallothionein (CuMT) gene of Neurospora [K.S. Kumar, S. Dayananda, C. Subramanyam, Copper alone, but not oxidative stress, induces copper-metallothionein gene in Neurospora crassa, FEMS Microbiol. Lett. 242 (2005) 45-50], we isolated and characterized the CDRE-binding protein. The cloned upstream region of CuMT gene was used as the template to specifically amplify CDRE element, which was immobilized on CNBr-activated Sepharose 4B for use as the affinity matrix to purify the CDRE binding protein from nuclear extracts obtained from Neurospora cultures grown in presence of copper. Two-dimensional gel electrophoresis of the affinity purified protein revealed the presence of a single 17kDa protein, which was identified and characterized by MALDI-TOF. Peptide mass finger printing of tryptic digests and analysis of the 17kDa protein matched with the regulatory beta-subunit of calcineurin (Ca(2+)-calmodulin dependent protein phosphatase). Parallel identification of nuclear localization signals in this protein by in silico analysis suggests a putative role for calcineurin in the regulation of CuMT gene expression.

Interrelations between oxidative stress and calcineurin in the attenuation of cardiac apoptosis by eugenol.

In view of the known involvement of oxidative stress and calcineurin (Ca(2+)-calmodulin dependent protein phosphatase) in beta-Adrenergic stimulated events, we examined the influence of eugenol (an antioxidant generally regarded as safe by the Food and Agricultural Organization of the United Nations) on isoproterenol-induced apoptosis in neonatal cardiomyocytes. In comparison to unstimulated controls, cardiomyocytes stimulated with 50 microM isoproterenol for 48 h demonstrated (a) increased intracellular Ca(2+) levels (b) oxidative stress involving enhanced reactive oxygen species, decreased GSH/GSSG ratio, enhanced lipid peroxidation, increased activities of superoxide dismutase and glutathione peroxidase (c) apoptosis, evidenced by increased number of annexin V/TUNEL positive cells, enhanced membrane fluidity, decreased mitochondrial membrane potential, increased activities of caspase 3 and 9 along with (d) increased calcineurin activity. Pre-incubation of cardiomyocytes with 100 microM eugenol for 1 h, followed by isoproterenol treatment for 48 h, led to reversal of enhanced intracellular Ca(2+) levels, oxidative stress, calcineurin activation and apoptosis caused by isoproterenol. In addition, similar treatment of cardiomyocytes with 10 nM FK506, a calcineurin inhibitor, could also attenuate isoproterenol-induced apoptosis. These results indicate the beneficial effects of eugenol in preventing cardiomyocyte apoptosis.

Positive correlations between serum calcineurin activity and left ventricular hypertrophy.

BACKGROUND: Among various intracellular signaling cascades associated with cardiac hypertrophy, the involvement of calcineurin (CaN; Ca2+-calmodulin dependent protein phosphatase) is gaining credence because of its enhanced activity in ventricular myocardium and the ability of CaN inhibitors to prevent pressure-overload hypertrophy. Since our recent findings attribute clinical significance to serum CaN, the present investigation was conducted to evaluate its significance in cardiac hypertrophy. METHODS: The study group comprised of patients diagnosed for hypertensive hypertrophy, hypertrophic cardiomyopathy, chronic coronary artery disease with compensatory left ventricular hypertrophy, dilated cardiomyopathy and acute myocardial infarction. Serum contents of CaN and calmodulin were determined and activities of CaN as well as of acid and alkaline phosphatases were assayed and correlated with 2D echocardiography findings. The results were compared with those obtained from age-matched healthy volunteers. RESULTS: Serum CaN activity, but not of acid or alkaline phosphatases, was significantly enhanced by 2-fold in hypertensive hypertrophy, 3-fold in hypertrophic cardiomyopathy and 3.75-fold in chronic coronary artery disease associated with left ventricular hypertrophy, unaccompanied by changes in serum contents of calmodulin and CaN. No such increases were observed in acute myocardial infarction and dilated cardiomyopathy. CONCLUSIONS: Positive correlations observed between serum CaN activity and enhanced left ventricular mass in cardiac hypertrophy suggest that assaying serum CaN activity may be useful in the diagnosis and management of left ventricular hypertrophy.