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Biomedical subjects

Banumathi Ramakrishna

Publications and source records attributed to Banumathi Ramakrishna.

9 recordsLinked to original sources

Insulin secretory characteristics of monkey pancreatic islets: a simple method of islet isolation and the effect of various density gradients on separation.

We describe a simple stationary digestion method of islet isolation and separation by various density gradients from monkey pancreas (Macaca radiata radiata). Effective method, different types and concentrations of collagenase were standardized. Sigma type XI collagenase yielded >1000 islets/gram pancreas at the concentration of 4 mg/ml and 3 ml Hank's/gram pancreas. Slow digestion with less concentration of collagenase was suitable for monkey islet isolation. Discontinuous density gradients of bovine serum albumin (BSA) and dextran were compared with standard Ficoll for separation of islets. Islet yield (1038 +/- 81), insulin secretory response (stimulation index, S.I.11) and histological examination revealed dextran gradients were more appropriate for monkey islets when compared to BSA and Ficoll. Insulin secretory characteristics of monkey islets were studied by exposing them to low and high concentrations glucose (S.I.11.5), arginine (S.I.4.2), leucine (S.I.2.3) and tolbutamide (S.I.1.7). The results indicated that the magnitude of glucose induced insulin secretion of monkey islet is about half as that of rat and mouse islets. However, it is higher than that of porcine and bovine islets. In conclusion, the knowledge of insulin secretory ability of Indian bonnet monkey islets together with the techniques of isolation and separation are useful tool for diabetic research especially islet transplantation.

Amino Acids↗

Histopathological study of chronic hepatitis B and C: a comparison of two scoring systems.

BACKGROUND/AIMS: Several histological scoring systems are used to evaluate chronic viral hepatitis. This study was undertaken to determine the correlation between the Ishak system (modified histological activity index, HAI) and the METAVIR system, in Indian patients with chronic viral hepatitis. METHODS: Liver biopsies from 127 patients with chronic viral hepatitis B or C were examined, and scored using the Ishak and METAVIR systems, and weighted kappa analysis of correlation was done. Correlation of necroinflammatory activity with serum transaminase levels was analyzed, and prevalence of specific histological features compared in hepatitis B virus (HBV) and HCV biopsies. RESULTS: HBV infection accounted for 64.6% of cases, and HCV for 35.4%; 91.3% of patients had minimal or mild hepatitis. The necroinflammatory scores of the Ishak and METAVIR systems correlated moderately well (weighted kappa 0.627), while there was excellent correlation with regard to fibrosis (weighted kappa 0.998). Similar concordance was found when HBV and HCV cases were analyzed separately. HAI showed poor correlation with serum transaminases (weighted kappa 0.21). Micronodular cirrhosis, lymphoid aggregates, bile duct damage, bile ductular proliferation and steatosis were significantly more common in HCV biopsies compared to HBV. CONCLUSIONS: Concordance between Ishak and METAVIR scoring systems is good for necroinflammatory change, and excellent for fibrotic change.

Adult↗

Oxidative damage to the hepatocellular proteins after chronic ethanol intake in the rat.

BACKGROUND: Protein carbonyl content, a measure of oxidative damage to hepatocellular proteins, and the activities of some thiol-containing proteins were assayed in the liver and plasma, as thiol-containing protein, appear to be targets for free radicals. These may be important in the mechanism of ethanol-induced liver injury. METHODS: Tap water containing ethanol at the concentration of 25% (v/v) and phenobarbital (500 mg/l) was the only source of drinking water for the experimental rats for 24 months. Another group of rats were administered 25% (v/v) ethanol alone in drinking water for 24 months. Control rats were administered either phenobarbital alone in drinking water or tap water for 24 months. At the end of 24 months, the rats were sacrificed. The protein carbonyl content, activities of glutamine synthase and biotinidase-sulfhydryl group containing enzymes were assayed in the liver along with alkaline protease, an enzyme that degrades oxidized proteins. The total thiol, albumin and the activity of biotinidase were measured in the plasma. RESULTS: The protein carbonyl content of the liver was increased in the ethanol/phenobarbital-treated rats as well as in the ethanol-treated rats as compared with the controls. The activities of glutamine synthase and biotinidase were decreased significantly in the livers of ethanol/phenobarbital-treated rats as well as the ethanol-treated rats as compared with the controls. The activity of alkaline protease was increased significantly in both the ethanol-treated groups. In the plasma of ethanol/phenobarbital-treated rats as well as the ethanol-treated rats total thiol, albumin and the activity of biotinidase were decreased significantly as compared with the controls. The ethanol/phenobarbital-treated rats as well as the ethanol-treated rats developed fatty liver. CONCLUSIONS: Damage to proteins occurs upon chronic ethanol intake in the rat, and it may play a role in the pathogenesis of alcohol-induced fatty liver.

Animals↗

Reduction of immunogenicity by cyclophosphamide pretreatment and culture on xenograft survival of monkey pancreatic islets transplanted into rats.

INTRODUCTION: Islet cell transplantation offers a new approach for the treatment of diabetes. Before transplantation, immunomodulation procedures are conducted to reduce the immunogenicity of the pancreatic islets. AIM: To study the effect of cyclophosphamide pretreatment and culture on the xenograft survival of monkey pancreatic islets. METHODOLOGY: Islets were isolated from normal monkeys and transplanted under the renal capsule of the rats. The grafts were removed 7 days after transplantation and processed for histologic study to examine graft survival. Islets from normal monkeys without cyclosporine treatment were destroyed in 7 days. These islets required cyclosporine (30 mg/kg) to prevent rejection. In the second group, the donor monkeys were treated with cyclophosphamide (60 mg/kg body weight) -4 and -2 days before harvesting of the islets. On day 0, the islets were isolated and cultured in RPMI-1640 medium for 7 days in 95% air and 5% CO2. After culture, the islets were transplanted into the rats. The grafts were removed and processed for histologic study to examine graft survival. RESULTS: The pretreated and cultured islets required 15 mg/kg cyclosporine to prevent rejection. Half of the usual dose of cyclosporine is enough to prevent rejection if the donor monkeys were pretreated and the islets cultured. CONCLUSION: This study shows that donor pretreatment and culture reduces immunogenicity of the xenotransplanted primate islets into rats.

Animals↗

Epithelioid haemangioendothelioma of the liver.

Epithelioid haemangioendothelioma is a well-recognized vascular neoplasm but can be mistaken for metastatic adenocarcinoma or other primary liver tumors. We present a case of epithelioid haemangioendothelioma of the liver in a 62 year old woman, in whom the diagnosis was missed by various pathologists. This patient presented with loss of appetite and weight, and fever. She rapidly deteriorated and died presumably of liver cell failure. The characteristic histological features and the positive immunostaining for endothelial markers (CD31 & Ulex europaeus) confirmed the diagnosis.

Female↗

Acute fatty liver of pregnancy: a report of two cases.

Acute fatty liver of pregnancy is an uncommon, potentially fatal disorder. Between 1998 and 2000, two patients with acute fatty liver of pregnancy presented at the Christian Medical College Hospital, Vellore. Both patients were in the thirty-sixth week of pregnancy. jaundice and encephalopathy were the predominant symptoms. Both the mothers died after they delivered a stillborn Infant each. The maternal deaths were due to multiorgan failure and/or postpartum haemorrhage and sepsis. The route of delivery was vaginal in both the patients. Extrahepatic and metabolic complications in both cases Included renal failure, sepsis, hypoglycaemia, disseminated intravascular coagulation and gastrointestinal bleeding. Liver biopsy done in both patients was consistent with the diagnosis of acute fatty liver of pregnancy. To the best of our knowledge, this is the first report from India on acute fatty liver of pregnancy.

Acute Disease↗

Liver histology and immunohistochemical findings in asymptomatic Indians with incidental detection of hepatitis B virus infection.

BACKGROUND AND OBJECTIVES: The relationship between hepatocyte expression of hepatitis B virus (HBV) antigens, liver histology and viral replication in asymptomatic subjects with incidental detection of hepatitis B surface antigen (HBsAg) remains unclear. We evaluated the histological activity index (HAI) and hepatocyte expression of viral antigens with replicative status in asymptomatic chronic HBV infection. METHODS: Asymptomatic subjects with incidental detection of HBsAg and ALT levels less than twice the upper limit of normal were grouped as follows: Group A - negative for HBeAg and HBV DNA (no HBV replication); B - HBeAg negative, HBV DNA positive (low HBV replication or pre-core mutant); C - positive HBeAg and HBV DNA (high viral replication). Liver biopsies were assessed for HAI (Ishak's scoring system). These were also subjected to immunohistochemistry for expression of HBsAg and hepatitis B core antigen (HBcAg); distribution, staining pattern and quantitative measurement of antigen expression were assessed. RESULTS: Median HAI was similar in the three groups (1.0, 2.0 and 2.0 in groups A, B and C, respectively). All subjects in Group C showed discrete cytoplasmic expression of HBsAg, whereas the other two groups showed heterogeneity in distribution and pattern of HBsAg staining. Quantitative measurement of cytoplasmic HBsAg revealed similar results in the three groups. Core antigen (nuclear) was detected in 4 of 5 subjects in Group C and none of those in Groups A and B. Ground-glass hepatocytes were seen in 20 and orcein-positive cells in 26 cases. HBsAg was detected by immunohistochemistry in 37 biopsies. CONCLUSIONS: Among asymptomatic subjects with chronic HBV infection, those with high rate of viral replication had discrete cytoplasmic HBsAg expression and nuclear expression of core antigen; these findings were uncommon in subjects with low or no viral replication.

Adult↗