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Biomedical subjects

V Burke

Publications and source records attributed to V Burke.

At least 163 records · Page 9Linked to original sources
PubMed1981

Detection of enterotoxins of Aeromonas hydrophila by a suckling-mouse test.

The suckling-mouse assay was reliable for detecting enterotoxigenic strains of Aeromonas hydrophila when standard conditions for growth and toxin testing were used. Enterotoxins were produced by bacteria grown in tryptone soya broth supplemented with yeast extract and aerated by shaking in an environmental incubator or water bath. When culture supernates together with dye were administered intragastrically to mice less than 6 days old, the presence of enterotoxin was assessed on the basis of a scoring system that incorporated the ratio intestinal weight: remaining body weight, and production of diarrhoea. This method should facilitate the detection of enterotoxigenic strains of Aeromonas in epidemiological studies.

Aeromonas↗
PubMed1980

Reduction by aspirin of intestinal fluid-loss in acute childhood gastroenteritis.

Soluble aspirin was given by mouth in therapeutic doses in a double-blind trial to malnourished infants and young children with gastroenteritis and dehydration. Faecal fluid-losses were reduced and weight-grain was enhanced in the group given aspirin. These effects were statistically significant when compared with those obtained with a placebo preparation and in a group of patients given supportive therapy but no specific drug treatment. The results suggest that aspirin may be useful in reducing intestinal fluid-loss in childhood gastroenteritis. Before the widespread use of aspirin can be recommended, its effects in patients not under hospital supervision must be determined.

Aspirin↗
PubMed1980

An experimental model of gastrointestinal candidiasis.

Intestinal absorption of arbutin (p-hydroxyphenyl-beta-glucoside), a non-metabolised analogue of d-glucose, and net flux of water out of the small intestinal lumen were found to be decreased in vitro in rats fed with Candida albicans. In rats on a protein-deficient diet and fed C. albicans there was net secretion of water. Sugar uptake and net water transport were also impaired in infected animals in vivo. These abnormalities were present although there was no histological evidence of invasion of the small-intestinal mucosa by C. albicans. The findings suggest that C. albicans has significant enteric pathogenicity and that this is particularly important in malnutrition.

Animals↗
PubMed1980

Effects of salicylate on intestinal absorption: in vitro and in vivo studies with enterotoxigenic micro-organisms.

This study was done to determine whether salicylate could affect alterations in intestinal absorption induced by preparations of enterotoxigenic micro-organisms. It was found in rats that salicylate increased intestinal monosaccharide uptake in vitro and reversed the inhibitory effects induced by cell-free preparations of Staphylococcus sp., Candida sp. and Klebsiella sp. In vivo, salicylates increased net water absorption in rat jejunum exposed to cell-free preparations of various micro-organisms. Increase in net fluid flux occurred after subcutaneous injection only with bacteria which stimulate adenylate cyclase activity. These observations suggest that the absorptive and anti-secretory effects of aspirin are cyclic nucleotide dependent. The potential clinical role of salicylates as anti-secretory agents in diarrhoeal diseases, particularly in children, requires further investigation.

Animals↗
PubMed1979

Defective Candida killing in childhood malnutrition.

This study shows that malnourished children have impaired candidacidal activity of leucocytes, a finding which runs parallel to the higher rates of isolation of Candida sp. from throat secretions. In well nournished subjects the mean candidacidal ability was 44.5% in the moderately undernourished group it was 17.6%, and in the severely malnourished group it was 13.7%. This impaired candidacidal capacity may be important in the establishment of large numbers of Candida sp. which are commonly found in the upper intestine and in the pathogenesis of diarrhoea in children with malnutrition.

Adult↗
PubMed1978

Intestinal transport of monosaccharide after biliary diversion in the rat.

Sugar absorption is increased in rats with a bile fistula but approaches normal values with the addition of bile salt. It has therefore been suggested that bile salts have a physiological role in decreasing intestinal absorption of monosaccharides. In experiments using rats, jejunal and ileal uptake of arbutin, a glucose analogue was increased 5 days after creating a bile fistula but normal by the 10th day after operation. Bile fistula rats ate only about one third of the intake of normal rats in the first 5 days after operation. Control animals fed the same amount as the bile fistula group showed a similar increase in jejunal and ileal arbutin uptake. In both groups, on the 5th post-operative day, addition of taurocholate depressed arbutin uptake towards normal. In normal rats, taurocholate depressed arbutin uptake in the ileum but not the jejunum. These results suggest that increased monosaccharide uptake in bile fistula rats is related to semi-starvation and is not a specific effect of bile salts.

Animals↗
PubMed1978

Effects of intestinal micro-organisms on fluid and electrolyte transport in the jejunum of the rat.

Culture filtrates of micro-organisms isolated from the upper intestinal secretions of malnourished children and grown in pure culture were shown to impair the intestinal absorption of water and electrolytes in live rats. Decreased net movement out of the intestinal lumen, or actual secretion of water, sodium or potassium into the intestinal lumen, was found with culture filtrates of single isolates of Staphylococcus epidermidis, Escherichia coli 055, Escherichia coli B7A, Shigella sonnei, Klebsiella pneumoniae, Candida albicans and Candida tropicalis. These organisms have been found to contaminate upper intestinal secretions in malnourished children and it is suggested that the effects observed in these experiments might be relevant to the production of the diarrhoea that is a dominant clinical feature of childhood malnutrition.

Animals↗
PubMed1977

Effect of enteric micro-organisms on intestinal sugar and fatty acid absorption.

The effect of micro-organisms contaminating the upper intestinal contents of malnourished children on intestinal absorption of 3-0 methyl-alpha-D-glucopyranose (3-M.G.) and oleic acid was studied in rats in vivo. Oleci acid absorption was unaffected by non-pathogenic E. coli but decreased by E. coli 0111, Salmonella paratyphi B., Shigella sonnei and Candida sp. This effect was probably explained by intestinal secretion diluting the test solution leading to a decreased diffusion gradient for solubilised fatty acid. Inhibition of sugar absorption occurred with bacterial suspensions of Staphylococcus aureus, Streptococcus faecalis, E. coli and Candida sp. and cell-free preparations of Staphylococcus aureus, Streptococcus faecalis, a non-pathogenic E. coli, Proteus sp., Klebsiella sp., Pseudomonas sp. and Candida sp. These effects were not explained by dilution of the test solution. This indicates that numerous micro-organisms and, in some instances, their cell-free preparations can interfere with intestinal active sugar transport. These findings may be relevant to the production of malabsorption in malnourished children who have a wide variety of micro-organisms contaminating their upper intestinal contents.

Animals↗
PubMed1977

Effects of biliary diversion on intestinal microflora in the rat.

Certain bile acids inhibit the growth in vitro of organisms commonly found in the intestine and, in particular, anaerobic bacteria. As the importance of this effect in vivo has not been demonstrated, we investigated changes in intestinal flora in the rat after diversion of bile to the urinary bladder. Five days after operation there was an increase in numbers of Proteus sp. in the stomach, mid-jejunum and caecum and of coliform bacilli in the stomach and mid-jejunum. Lacto-bacilli were increased in the stomach. There was no change in numbers of anaerobic organisms. Similar changes in bacterial flora followed 5 days of pair feeding in control rats. Our results do not suggest a specific antibacterial effect of bile salts in the rat in vivo. The changes found are probably related to semi-starvation, because the food intake of the rats after operation was about half that of control rats having an unrestricted diet.

Anaerobiosis↗
PubMed1976

Inhibition of intestinal uptake of amino acids by unconjugated bile salt.

The unconjugated bile salt, sodium deoxycholate, at a concentration of 0.5 mM was shown to inhibit the intestinal uptake of the amino acids L-glycine, L-leucine, L-proline, L-lysine and L-tyrosine in rats in vitro. This effect was acutely reversible except for the basis amino acid L-lysine and is therefore not simply due to tissue damage. These results, and the recent finding that sodium deoxycholate inhibits intestinal absorption of amino acids in vivo, suggest that impaired intestinal amino acid transport may contribute to hypoproteinaemia in patients with bacterial overgrowth in the upper small intestine in whom deoxycholate is present in the small intestinal lumen in excessive concentrations.

Amino Acids↗
PubMed1976

Extracellular calcium and adrenergic and cholinergic effects on islet beta-cell function.

An in vitro perifusion system utilizing collagen-medium calcium on the dynamics of insulin release as induced by acetylcholine (ACh) stimulation (in the presence of glucose, 2.4 mM) and as modified by prior perfusion of islets in epinephrine. Continuous challenge with ACh produces a biphasic insulin release response, both phases of which are reduced when the medium calcium concentration is reduced during stimulation; when the calcium content is reduced during an initial perifusion period of 30 min and then replaced during subsequent stimulation only the first phase of the response to ACh is affected; perifusion with epinephrine prior to stimulation with ACh produces enhancement of both phases of ACh-induced insulin release when calcium in both media is normal. However,.when this experiment is repeated utilizing a medium with low calcium content during the period of exposure to epinephrine the priming effect of epinephrine on the subsequent insulin response to ACh is abolished (in fact, reversed). These studies provide direct evidence for a role for calcium in mediating an effect of epinephrine on insulin release. Further, the data suggest that epinephrine affects Ca transport in islets in some manner beyond stimulating net efflux from islets, perhaps by enhancing membrane binding of calcium.

Acetylcholine↗
PubMed1976

Effect of streptozotocin on red-blood-cell-reduced glutathione: modification by glucose, nicotinamide, and epinephrine.

Previous studies had shown that administration of streptozotocin to rats produces both diabetes and hemolysis and that both could be ameliorated by prior injections of diazoxide. Thus, it appeared pertinent to define the effect of streptozotocin on the red cell. In the present studies, streptozotocin administered in vivo to rats produced a rapid fall in red-cell-reduced glutathione. This effect was duplicated in vitro in incubated human red cells. Furthermore, it was demonstrated that glucose loading prior to bleeding modified the in-vitro red-cell GSH response to streptozotocin and that preincubation of red cells from fasted individuals with glucose, nicotinamide, and epinephrine (but not nicotinic acid) protected against the subsequent effect of streptozotocin on RBC GSH. The pattern of the RBC GSH response under each of these conditions is that which occurs in response to challenge with an oxidant, that is, with appropriate protection, oxidation stress produces an acute rise rather than falll in gsh. further, when glucose was present through both preincubation and test periods (i.e., in presence of streptozotocin) a third pattern of GSH response was observed--no change. The data are compatible with the postulate that the cytotoxic action of streptozotocin is dependent, in part, on an oxidant effect, and that glucose may protect through at least two mechanisms, that adrenergic stimulation can enhance protective mechanisms against redox insults and so contribute to maintenance of cell viability.

Animals↗
PubMed1975

Effect of microorganisms isolated from the upper gut of malnourished children on intestinal sugar absorption in vivo.

The effect of microorganisms isolated from the upper gastrointestinal tract of malnourished children on intestinal sugar absorption was studied in rats in vivo. Pure cultures of organisms were grown overnight in a nutrient broth and the resultant supernatant fluid which contained microorganisms in similar numbers to those found in the patients was used as the basic solution for jejunal perfusions which were done in anesthetized adult Wistar rats. The substrate used was arbutin (p-hydroxphenyl-beta-glucoside), a recognized marker of intestinal active sugar transport. Of the gram-positive cocci studied, only the saprophyte, Staphylococcus saprophyticus, did not adversely affect the intestinal absorption of arbutin. The only gram-positive rod studied, a lactobacillus, also significantly inhibited arbutin absorption. Of the Enterobacteriaciae studied, Salmonella paratyphi B, a Shigella and Proteus sp. did not affect arbutin absorption. All the species of Escherichia coli studied, including a nonpathogenic variety, inhibited absorption. Klebsiella sp. and Pseudomonas sp. were also effective. Of the Candida sp., C. albicans and C. parapsilosis were inhibitory while C. tropicalis was not. These results suggest that microorganisms not generally considered enteropathogenic may adversely affect intestinal function when present in the lumen of the gut in excessive numbers and contribute to the production of diarrhea in children with malnutrition.

Animals↗
PubMed1975

Inhibition of intestinal amino acid absorption by unconjugated bile salt in vivo.

The intestinal absorption of five amino acids studied (L-lysine, L-glycine, L-leucine and L-tyrosine) and one dipeptide (glycylglycine) was significantly inhibited by the deconjugated bile salt, sodium deoxycholate, in rats in vivo. It is suggested that inhibition of absorption of amino acids and dipeptides by unconjugated bile salts may contribute to hypoproteinaemia in patients with the contaminated small-bowel syndrome.

Amino Acids↗
PubMed1973

Effects on small-intestinal function and structure induced by feeding a deconjugated bile salt.

Feeding sodium deoxycholate orally to rats for three days caused inhibition of small-intestinal active sugar transport and ouabain-sensitive, sodium-potassium-dependent adenosine triphosphatase activity. At the same time, there was evidence of extensive ultrastructural damage to the microvillar and intracellular compartments of the small-intestinal epithelium while its light microscopic appearance was essentially normal. These functional and morphological changes reverted towards normal over the subsequent four days when a normal diet, without added bile salt, was reintroduced.

Adenosine Triphosphatases↗