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Biomedical subjects

B S Ramakrishna

Publications and source records attributed to B S Ramakrishna.

At least 55 records · Page 3Linked to original sources
PubMed1996

Isolation of Vibrio cholerae O139 from the drinking water supply during an epidemic of cholera.

In mid-1994, the public water supply was investigated in a medium-sized town in south India during an epidemic of cholera due to Vibrio cholerae O139. Vibrio cholerae O139 was isolated from the public water supply including one of the wells supplying the town, the central overhead tank, and domestic taps connected to the public supply. Following chlorination, the organism was no longer isolated from the water supply and the epidemic subsided. This demonstration of V. cholerae O139 in the drinking water supply of a town underlines the need for adequate treatment of the water supply.

Adolescent↗
PubMed1996

Colonic fluid handling in health & acute diarrhoeal diseases.

The ability of the colonic epithelium to actively absorb sodium against electrochemical gradients confers on it the capacity to dehydrate the faeces. This capacity is of considerable importance in limiting fluid losses in acute diarrhoeal illnesses characterised primarily by small intestinal fluid secretion. Even in these illnesses, colonic absorptive capacity may be altered for various reasons. Loss of colonic absorptive capacity is also responsible for diarrhoea in those illness where the pathology is primarily epithelial cell damage in the large bowel. The present review analyses the information available on this subject from studies in patients with acute diarrhoea, and in experimental animals. It also outlines measures that might possibly restore optimal function of the colonic salvage mechanism in acute diarrhoeal disease.

Acute Disease↗
PubMed1995

Prevalence and presentation of hepatitis C related chronic liver disease in southern India.

To determine the importance of hepatitis C virus (HCV) infection in the aetiology of chronic liver disease in southern India, the prevalence of HCV antibodies and HBV markers was estimated in 100 patients with chronic liver disease and in 56 patients with a variety of other gastrointestinal and liver diseases who served as controls. HCV antibody was measured by a second-generation ELISA. HBsAg, anti-HBc, anti-HBs and anti-D were also estimated. HCV antibodies were detected in 26/100 patients with chronic liver disease compared to 0/56 controls. HBV markers were present in 72 of 100 patients with chronic liver disease compared to 21/56 (37.5%) controls. Anti-D was noted in 4/100 patients with chronic liver disease and in none of the controls. Many patients had serological evidence of both B and C infection; 73% of those with anti-HCV also tested positive for HBV markers. HCV related disease presented at a median age of 60 years compared to HBV related disease which presented at a median age of 40. There was no significant difference between HCV and HBV positive patients in symptomatology, but encephalopathy was uncommon and cirrhosis the usual finding at histology in HCV positive individuals, while chronic active hepatitis was found in 30% of biopsied HBV related disease. HCV is a significant cause of chronic liver disease in this geographic region, although HBV infection continues to account for the largest proportion of cases.

Adolescent↗
PubMed1994

Alteration of colonic absorption by long-chain unsaturated fatty acids. Influence of hydroxylation and degree of unsaturation.

Unabsorbed dietary unsaturated fatty acids may cause diarrhea in patients with steatorrhea, but their ability to cause colonic fluid secretion is not known. The present study investigated the effect of several dietary long-chain unsaturated fatty acids on colonic absorption and morphology in the rat colon in vivo. The fatty acids tested induced concentration-dependent net water secretion. The ability of these fatty acids to induce net water secretion varied as follows: linolenic acid (18:3) > linoleic acid (18:2), ricinoleic acid (18:1 OH) > oleic acid (18:1), palmitoleic acid (16:1). Net absorption of sodium and chloride were decreased in fatty acid perfusions. Mucosal activity of sodium potassium adenosine triphosphate and adenyl cyclase were not significantly altered by fatty acids. Epithelial cell damage was noted and correlated with the ability of the fatty acid to induce fluid secretion. Unsaturated fatty acids induce epithelial cell damage and fluid secretion in the colon, their effect being related to the degree of unsaturation.

Adenylyl Cyclases↗
PubMed1993

Colonic dysfunction in acute diarrhoea: the role of luminal short chain fatty acids.

Faecal concentrations and output of short chain fatty acids (SCFA) were assessed on successive days by gas-liquid chromatography in 24 patients with acute watery diarrhoea. Absorption of water and sodium from the rectum was also measured by a dialysis technique in 17 of these patients and in nine normal subjects in the presence and absence of luminal SCFA. Faecal SCFA concentrations were low on the first day of diarrhoea (mean (SEM) 9.9 (5.8) mmol/kg) and increased to 94.8 (16.4) mmol/kg by the fifth day. Faecal output of SCFA corresponded to these figures. Net water absorption, in the absence of luminal SCFA, was stopped in patients with acute diarrhoea (-59 (81) nl/cm2/min) compared with healthy controls (+322 (63) nl/cm2/min) (p < 0.01). Luminal SCFA restored net water absorption to +184 (67) nl/cm2/min in patients with acute diarrhoea (p < 0.01). Net absorption of sodium decreased in patients with acute diarrhoea in the absence of luminal SCFA, but returned to normal with luminal SCFA. Net secretion of potassium increased in acute diarrhoea, and did not change in the presence of SCFA. Defective absorption from the rectum in acute diarrhoea is reversed by luminal SCFA. The reduction of luminal SCFA in acute diarrhoea treated conventionally may be a factor contributing to colonic dysfunction.

Acute Disease↗
PubMed1992

Colonoscopic study of 50 patients with colonic tuberculosis.

Fifty patients with colonic tuberculosis are reported in whom a colonoscopic diagnosis confirmed by histological examination was possible in 40. Bacteriological studies did not increase the diagnostic yield. Abdominal pain was the most common symptom (90%) and an abdominal mass the most common abnormal physical finding (58%). A nodular mucosa with areas of ulceration was the usual colonoscopic finding. Ileocaecal disease was found in 16, ileocaecal and contiguous ascending colon disease in 14, segmental colonic tuberculosis in 13, ileocaecal disease and non-confluent involvement of another part of the colon in five, and pancolitis in two patients. This report emphasises that colonoscopy is a useful procedure for diagnosing colonic tuberculosis and that segmental colonic tuberculosis is not uncommon.

Biopsy↗
PubMed1991

Impaired sulphation of phenol by the colonic mucosa in quiescent and active ulcerative colitis.

Substantial amounts of phenols are produced in the human colon by bacterial fermentation of protein. In the colonic mucosa of animals, phenols are inactivated predominantly by conjugation with sulphate. The purpose of this study was to confirm sulphation of phenols by isolated colonocytes from man and to evaluate mucosal sulphation in inflammatory bowel disease using the phenol, paracetamol, in rectal dialysis bags. The incubation of paracetamol with colonocytes isolated from resected colon specimens (n = 7) yielded a mean (SE) value of 7.0 (0.9) mumols/g dry weight of paracetamol sulphate after 60 minutes but virtually undetectable values of paracetamol glucuronide. Paracetamol sulphate was detected in rectal dialysates from all control subjects, with a mean (SE) value of 4.2 (0.8) nmol/hour. Sulphation was significantly impaired (p less than 0.01) in 19 patients with active ulcerative colitis (0.6 (0.2) nmol/hour) and in 17 patients with ulcerative colitis in remission (1.1 (0.4) nmol/hour). Sulphation in eight patients with Crohn's colitis (4.3 (2.1) nmol/hour) was similar to that in control subjects. Impairment of the capacity of the mucosa to sulphate phenols in quiescent and active ulcerative colitis may pose a metabolic burden on colonic epithelial cells, which are continuously exposed to endogenous phenols from the colonic lumen.

Acetaminophen↗
PubMed1990

The effects of enterotoxins and short-chain fatty acids on water and electrolyte fluxes in ileal and colonic loops in vivo in the rat.

The effect of cholera toxin (CT) and Escherichia coli heat-stable enterotoxin (ST) on the ileum and colon was examined in vivo in the rat in an attempt to clarify the effects of enterotoxins on colonic mucosa and to determine if these effects were influenced by short-chain fatty acids (SCFA). Both CT and ST induced similar changes in water and electrolyte fluxes, and the magnitude of these changes in loops of colon was similar to that observed in loops of ileum. The addition of luminal SCFA, acetate, propionate and butyrate did not influence the effect of either toxin in loops of ileum. However, in loops of colon exposed to CT, luminal butyrate (40 mM) largely reversed the effect of CT by converting net water secretion (mean +/- SE, -363 +/- 154 nl.cm-2.min-1) to net water absorption (470 +/- 194 nl.cm-2.min-1) and by significantly reducing the net secretion of sodium ions. In loops of colon exposed to ST, similar effects were observed although net water secretion (-784 +/- 114 nl.cm-2.min-1) was only partially reversed by butyrate (-318 +/- 102 nl.cm-2.min-1). In contrast to butyrate, acetate and propionate did not influence changes in colonic fluxes of water and sodium induced by enterotoxins. Oxidation of butyrate and glucose was observed to be depressed in colonocytes pre-exposed to CT but not to ST. In this model, colonic secretion induced by enterotoxins is similar to that observed in the ileum but differs from ileal secretion in its modulation by luminal butyrate.

Animals↗
PubMed1989

Estimation of phenolic conjugation by colonic mucosa.

Conjugation of phenol by the colonic mucosa was assessed in vivo using dialysis tubing containing 1.5 ml of 1 mmol/l acetaminophen (paracetamol) and 10 mmol/l butyrate. These were allowed to equilibrate in the rectum for one hour. The glucuronidated and sulphated conjugates of acetaminophen were measured by high pressure liquid chromatography and bicarbonate concentrations by gas analysis. In 21 subjects without colonic disease sulphate conjugation was observed in all cases, with a mean (SE) of 3.86 (0.66) nmol/hour, while glucuronide conjugation was found in seven of 21 cases. Mean (SE) bicarbonate output of 42.9 (3.9) mumol/hour (n = 21) indicated healthy colonic mucosal metabolism and phenolic sulphation in dialysate and agreed with published sulphation rates obtained with cultured cells of colonic epithelium. Acetaminophen sulphation suggests that the colonic mucosa has an important role in the conjugation of phenols, and the method reported here would be useful in assessing the detoxification capacity of the colonic mucosa in diseases of the rectal mucosa.

Acetaminophen↗
PubMed1988

Absorption of water and sodium and activity of adenosine triphosphatases in the rectal mucosa in tropical sprue.

In 10 southern Indian patients with tropical sprue, in vivo dialysis showed a defect of absorption of water and sodium from the rectum, when compared with 11 healthy volunteers. Sodium-potassium-ATPase activity, measured in homogenates of rectal biopsies, was significantly diminished in patients with sprue. Magnesium-ATPase and alkaline phosphatase were normal in biopsy homogenates. Decreased activity of colonic sodium-potassium-ATPase may contribute to diarrhoea in some patients with tropical sprue.

Humans↗
PubMed1987

Human erythrocyte gamma-glutamyltransferase in liver diseases.

The gamma-glutamyltransferase activity of erythrocytes was estimated in healthy adults and in patients with hepatobiliary disease. Control activity was 1.97 +/- 0.70 X 10(-4) U/mg ghost protein. Activity was elevated to 8.54 +/- 7.81 X 10(-4) U/mg in patients with hepatobiliary disease. Very high values, above 15 X 10(-4) U/mg were seen in patients with primary and secondary liver carcinoma, and also in some patients with obstructive jaundice. The erythrocyte enzyme had the same kinetic properties as serum and liver enzymes and was inhibited by serine-borate mixture, a specific inhibitor of the enzyme. There was no correlation between the erythrocyte enzyme level and either plasma hydrophobic enzyme level or erythrocyte glutathione content.

Electrophoresis, Polyacrylamide Gel↗
PubMed1987

Role of bacterial toxins, bile acids, and free fatty acids in colonic water malabsorption in tropical sprue.

Colonic perfusion studies in 10 southern Indian patients with tropical sprue and nine matched healthy adults revealed a defect of water and sodium absorption from the colon in sprue. Heat-labile and heat-stable enterotoxin production was not detected in coliforms cultured from the feces of any of the 19 subjects. The 24-hr fecal bile acid output was increased in patients with sprue, but fecal aqueous bile acid concentrations remained within normal limits, and these did not correlate with defects in colonic water and sodium absorption. Fecal free fatty acid excretion was markedly increased in sprue. There was a negative correlation between fecal excretion of unsaturated free fatty acids and colonic water and sodium absorption.

Adult↗
PubMed1982

Water and electrolyte absorption by the colon in tropical sprue.

A defect in colonic absorption of electrolytes and water was demonstrated in patients with tropical sprue by perfusing the colon with normal saline containing a non-absorbable marker. Colonic water absorption correlated negatively with stool weight and was abnormal in patients with steatorrhoea. The possible mechanisms producing this defect are discussed. This defect may be related to colonocyte damage produced by unabsorbed unsaturated fatty acids in patients with steatorrhoea.

Colon↗