Search PubMed⌕ Search

Biomedical subjects

S Hay

Publications and source records attributed to S Hay.

8 recordsLinked to original sources
PubMed1990

Effect of different carbohydrates on growth, polysaccharidase and glycosidase production by Bacteroides ovatus, in batch and continuous culture.

Bacteroides ovatus was grown in batch culture on 12 different carbon sources (five polysaccharides, seven monosaccharides and disaccharides). Specific growth rates were determined for each substrate together with polysaccharidase and glycosidase activities. Growth rates on polymerized carbohydrates were as fast or faster than on corresponding simple sugars, demonstrating that the rate of polysaccharide depolymerization was not a factor limiting growth. Bacteroides ovatus synthesized a large range of polymer-degrading enzymes. These polysaccharidases and glycosidases were generally repressed during growth on simple sugars, but arabinose was required for optimal production of alpha-arabinofuranosidase. Polysaccharidase and glycosidase activities were measured in continuous cultures grown with either xylan or guar gum under putative carbon limitation. With the exception of beta-xylosidase, activities of the polymer-degrading enzymes were inversely related to growth rate. This correlated with polysaccharide utilization which was greatest at low dilution rates. These results show that Bact. ovatus is highly adapted for growth on polymerized carbohydrate in the human colon and confirm that the utilization of polysaccharides is partly regulated at the level of enzyme synthesis.

Bacteroides↗
PubMed1990

A study of protein turnover in preterm neonates using 15N enrichment of urinary ammonia.

Hydrolysed yeast protein labelled with 15N was used to measure protein turnover, protein synthesis and protein breakdown in preterm infants. The yeast tracer was given as a bolus intragastric dose and protein turnover was determined from the 15N enrichment of urinary ammonia over known periods of about 12 h. Six boys (birthweight less than 1500 g) with gestation of 27-35 weeks were studied either two or three times at post-natal ages ranging from 13 to 54 d. There was no significant correlation between protein turnover with increasing post-conceptional or post-natal age. There was considerable interindividual variation and reproducibility varied between different infants. We suggest that this is a convenient non-invasive technique for monitoring serially nitrogen and protein metabolism in infants and that as such it merits further assessment.

Ammonia↗
PubMed1989

Effect of cyclosporine-A on connective tissue deposition in experimental inflammatory lesions.

The effect of cyclosporine-A, a potent immunosuppressant, on the development of experimental inflammatory lesions in rats was studied both histologically and biochemically. Continuous treatment with cyclosporine was begun after the implantation of sponges impregnated with heat-killed Mycobacterium tuberculosis and continued for up to 63 days. Cyclosporine-A significantly reduced the numbers of neutrophil polymorphonuclear leukocytes and lymphocytes present during both the acute and chronic phases. In addition, greater amounts of mature fibrous tissue were present in the sponges removed from animals which had been treated with cyclosporine-A. Biochemical analyses of the collagen and glycosaminoglycan content of the sponges at varying times confirmed that cyclosporine-A can influence the deposition of connective tissue macromolecules. These data provide additional evidence that cyclosporine-A affects not only the inflammatory response but also influences subsequent connective tissue metabolism.

Animals↗
PubMed1989

Influence of mucin on glycosidase, protease and arylamidase activities of human gut bacteria grown in a 3-stage continuous culture system.

Human intestinal bacteria were grown in a 3-stage continuous culture system on a medium containing complex polysaccharides and proteins as carbon and nitrogen sources. Selected bacterial populations were enumerated and glycosidase, protease and arylamidase activities measured. Comparison of arylamidase and glycosidase activities in the multichamber system (MCS) and faeces showed that the predominant faecal enzymes were also produced by bacteria growing in the MCS. After 48 d operation, porcine gastric mucin (5.8 g/d) was independently fed to vessel 1. Elevated levels of volatile fatty acid (VFA) formation showed that the glycoprotein was actively fermented. The increase in carbohydrate availability as a result of breakdown of the mucin oligosaccharides stimulated bacterial growth and activities. The enzymological measurements showed that mucin increased production of both cell-bound and extracellular glycosidases, such as beta-galactosidase, alpha-glucosidase and N-acetyl-beta-glucosaminidase. Protease activities were profoundly influenced by mucin. These were largely cell-bound in non-mucin cultures but were predominantly extracellular and collagenolytic when mucin was present. Experiments with protease inhibitors showed that cysteine proteases were the major cell-bound and extracellular enzymes in both mucin and non-mucin cultures, but that serine and metalloproteases were also present. The effect of mucin on arylamidase formation was less marked, although there was increased production of these enzymes in vessels 1 and 2 of the MCS. These results suggest that host-produced substances such as mucin glycoprotein may play a role in modulating the growth and activity of bacteria growing in the human large intestine.

Aminopeptidases↗
PubMed1989

Significance of microflora in proteolysis in the colon.

Protease activities in human ileal effluent and feces were compared by using a variety of native and diazotized protein substrates. In many cases the diazotized proteins had altered susceptibilities to hydrolysis compared with the native proteins. Proteolytic activity was significantly greater than (P less than 0.001) in small intestinal effluent than in feces (319 +/- 45 and 11 +/- 6 mg of azocasein hydrolyzed per h per g, respectively). Moreover, fecal proteolysis was qualitatively different in that ileal effluent did not hydrolyze the highly globular protein bovine serum albumin, whereas all fecal samples tested degraded this substrate. Inhibition experiments provided further evidence that fecal protease activity differed from that in the small intestine. Physical disruption of fecal bacteria released large quantities of proteases, indicating that the lysis of bacteria in the colon may contribute to the extracellular proteolytic activity in feces. Protease inhibition studies with washed fecal bacteria showed that they produced serine, cystine, and metalloproteases, and experiments with synthetic p-nitroanilide substrates indicated that low levels of trypsin- and chymotrypsin-like activities were associated with whole cells. An elastase-like enzyme was bound to the outer membranes of some fecal bacteria.

Bacteria↗
PubMed1976

Extraocular muscles: light microscopy and ultrastructural features.

Thirty extraocular muscles (EOM) from 20 patients were evaluated by light microscopy (LM), electron microscopy (EM), and enzyme histochemistry (EZH). Twenty-one EOM were obtained from 13 patients with strabismus, 9 EOM from 4 patients undergoing eye surgery for other reasons and from 3 autopsy cases. One mum thick sections revealed marked variation in muscle fibre shape and size and in myofibrillar structure; also noted were small, hypertrophied, whorled, and ringbinden fibres. Dense and granular material in the central portion of some fibres and sarcomere disruption in 2--3 mum sections was observed. EZH revealed the absence of the classical mosaic pattern usually found in skeletal muscles. ATPase studies were inconsistent and did not correlate with the expected reciprocal activity of NAD-H diaphorase, particularly on the large fibres. Ultrastructural features consisted of vacuoles within myofilament bundles, "smearing" of Z bands, and "nemaline rods". Occasional myelin figures and lipid-like droplets were observed in subsarcolemmal spaces, associated with scattered clusters of glycogen granules. Abnormal mitochondria and subsarcolemmal inclusions of dense and granular material were conspicuous. "Leptomeric" profiles, "Zebra bodies", or "striated bodies" were noted in 8 EOM's, and an Hirano body was found in 1. The intramuscular nerves contained structures resembling "Luse bodies" in 7 cases. These observations suggest that EOM from individuals with and without strabismus possess unique structural characteristics suggestive of developmental and morphological disarrangement of contractile elements. Some of these changes might play a role in the pathogenesis of strabismus and in the development of clinical symptoms. These features are significantly different from striated skeletal muscle. Therefore the criteria used in the pathological evaluation and diagnosis of skeletal muscle disorders cannot be unequivocally applied to EOM investigations. These data establish the necessity to determine histological norms, ultrastructural patterns, and develop new enzyme histochemistry criteria for the evaluation of EOM. Only then can an acceptable comparison of EOM and skeletal muscle be made.

Adenosine Triphosphatases↗
PubMed1976

Water fluoridation and congenital malformations: no association.

The incidence of selected congenital malformations in areas with fluoride supplementation of public water supplies was compared with the incidence in areas where the water supply is deficient in fluoride. Comparison of the incidences of several common birth defects (including Down's syndrome) in fluoridated and nonfluoridated areas revealed no substantial or significant differences in which there was a consistent pattern for both sets of data.

Adult↗