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Biomedical subjects

D C Savage

Publications and source records attributed to D C Savage.

At least 55 records · Page 3Linked to original sources
PubMed1986

Adhesion of Candida albicans to mouse intestinal mucosa in vitro: development of the assay and test of inhibitors.

This study describes an in-vitro assay for estimating numbers of Candida albicans adherent to mouse intestinal mucosa. No significant differences were observed in the capacity of C. albicans to adhere to genetically distinct mouse strains nor in the binding ability of three C. albicans strains. Chitin soluble extracts, prepared from chitin isolated from C. albicans or from chitin obtained commercially, inhibited adhesion of the yeasts to duodenal tissue by 48% and 43%, respectively.

Adhesiveness↗
PubMed1985

Purification and characterization of flagella from Roseburia cecicola, an obligately anaerobic bacterium.

Flagella from Roseburia cecicola, an obligately anaerobic bacterium originally isolated from murine caecal mucosa, were purified by mechanical shearing followed by differential centrifugation. Purity of the flagellar preparation was determined by polyacrylamide gel electrophoresis, electron microscopy and chemical analysis. The flagella were composed of a single protein subunit (flagellin) with an estimated molecular weight of 42 000. The amino acid composition of the flagellin was similar to that of some facultatively anaerobic and aerobic bacteria.

Amino Acids↗
PubMed1985

The diabetic with a diabetic parent.

Six of eight children with diabetes who have a parent with type I diabetes mellitus presented serious management problems. The doctor and diabetic health visitor should be aware that these families may require extra support.

Adolescent↗
PubMed1985

Pubertal growth in diabetics.

Mean values for two variables of the pubertal growth spurt, peak height velocity and age at peak velocity, of children attending the diabetic clinic in Bristol are reported. The growth spurt was normal both in timing and intensity in boys, but the peak velocity was reduced and age at peak velocity more variable among girls.

Adolescent↗
PubMed1985

Reversible inhibition of central precocious puberty with a long acting GnRH analogue.

A 7 year old girl with precocious puberty was treated with buserelin, a long acting analogue of gonadotrophin releasing hormone. Spontaneous and stimulated gonadotrophin secretion became prepubertal but returned to pubertal values when buserelin was withdrawn, suggesting that normal sexual maturation should follow cessation of treatment.

Buserelin↗
PubMed1985

Growth hormone responses to sleep, insulin hypoglycaemia and arginine infusion.

This study compares the peak serum growth hormone (GH) concentration during slow wave sleep with the serum GH responses to insulin-induced hypoglycaemia and intravenous arginine infusion in 23 children referred because of short stature (20) or precocious puberty (3). Peak serum GH concentration during sleep correlated significantly with peak GH response to insulin hypoglycaemia (r = 0.64, p less than 0.01) and arginine infusion (r = 0.57, p less than 0.01). 3 children had subnormal (less than 15 mU/l) peak serum GH concentrations during sleep but normal responses to either insulin-induced hypoglycaemia or intravenous arginine infusion. 1 child had a normal peak serum GH response to sleep but subnormal responses to insulin and arginine. Sleep studies of GH secretion may be indicated when the GH responses to pharmacological stimuli are inconsistent with the observed growth pattern.

Adolescent↗
PubMed1984

Motility as a factor in bowel colonization by Roseburia cecicola, an obligately anaerobic bacterium from the mouse caecum.

Roseburia cecicola strain GM is a motile obligate anaerobe that was isolated from mouse caecal mucosa. Twenty-five strains of motility mutants were obtained from populations of strain GM (wild-type) that had been exposed to UV light. Unlike GM cells, mutant bacteria were either non-motile and non-flagellated (Fla-) or migrated slowly or atypically in semi-solid medium. Strain GM and two mutant strains, SLS (Fla-) and WES (atypically motile), were used in mouse colonization experiments. In separate experiments, each strain colonized (4.8 X 10(9) to 1.5 X 10(10) c.f.u. per g caecum) the caecum of germfree mice inoculated intragastrically with pure cultures of the bacteria. In mice mono-associated with either mutant strain, bacteria which were non-motile or atypically motile predominated in their caeca (greater than 99% of total bacteria recovered). In mice mono-associated with motile cells of strain GM, mutant strains which had lost wild-type motility became predominant in the caecal populations (97% of total bacteria recovered at 48 to 70 days after inoculation). Mice mono-associated with either strain SLS or strain GM were colonized by one strain each of Escherichia coli, Candida pintolopesii, a Bacteroides sp., and a Clostridium sp. Most (99%) of the R. cecicola cells recovered from the caeca of these animals had typical wild-type motility. Motility, although not essential for R. cecicola to colonize germfree mice, is apparently advantageous to this bacterium when other micro-organisms are present with it in the mouse caecum. Motility may thus be essential for R. cecicola to colonize conventional laboratory mice.

Animals↗
PubMed1984

Gonadotrophin responses to GnRH in precocious puberty treated with GnRH analogue.

The gonadotrophin releasing hormone analogue Buserelin was given by intranasal spray to 13 children with precocious puberty. The LH responses to GnRH reverted to prepubertal levels in the boys on 200-400 micrograms daily of the analogue while doses of 400-1200 micrograms daily were needed to suppress the girls. The significance of this apparent sex difference is uncertain.

Buserelin↗
PubMed1984

Host specificity of filamentous, segmented microorganisms adherent to the small bowel epithelium in mice and rats.

Germfree rats and mice were given by gavage samples of ileal homogenates prepared from conventional rats and mice. Filamentous, segmented procaryotes adhered to the small bowel epithelium in the ex-germfree mice only when the homogenate was made from mouse bowel and in the ex-germfree rats only when the inoculum came from rats. Thus, the filamentous microorganisms are host animal specific.

Animals↗
PubMed1984

Serum resistance encoded by colicin V plasmids in Escherichia coli and its relationship to the plasmid transfer system.

Eight colicin V plasmids were conjugated into a plasmidless Escherichia coli (K-12) strain that was susceptible to the bactericidal effects of normal rabbit serum. The resulting colicin V-positive strains were examined for their capacity to resist the lethal effects of serum. Serum resistance was assessed as growth of the bacterial strain in medium containing 5% normal rabbit serum inoculated from a culture in the early exponential phase. Only three of the eight colicin V plasmids were found to confer the serum resistance phenotype on the host strain. Derepression of the transfer system was associated with serum resistance in two of the plasmids. Two other derepressed plasmids did not confer serum resistance on the host bacterium. Therefore, such derepression alone was insufficient to produce serum resistance. The factor(s) encoded by colicin V plasmids and responsible for the serum resistance of the bacterial strains bearing the plasmids was shown to be a property associated with the cell and not an extracellular factor excreted into the growth medium.

Animals↗
PubMed1983

Colonization of gnotobiotic mice by Roseburia cecicola, a motile, obligately anaerobic bacterium from murine ceca.

In scrapings of mouse cecal mucosae, motile bacteria outnumbered nonmotile bacteria by a ratio of 2:1. Obligately anaerobic bacteria were obtained from such scrapings through the use of techniques designed for the selective isolation of motile bacteria. One of the isolates, Roseburia cecicola, was rapidly motile in broth by means of 20 to 35 flagella arranged in a fascicle on each cell. R. cecicola cells colonized germfree mice (3 x 10(9) to 1 x 10(10) CFU/g of cecum) within 11 days after the animals were inoculated intragastrically with 2 x 10(8) CFU per mouse. In such monoassociated gnotobiotes, the bacteria were found primarily in the cecum, dispersed in the lumen among particles of digesta, and in the mucus over the epithelial surface. Between 2 and 3 weeks after birth, offspring of monoassociated adult mice were colonized by the bacterium (2 x 10(9) to 1 x 10(10) CFU/g of cecum). These results indicate that R. cecicola is suitable for studies of the ecology of host-associated microorganisms, particularly for investigation of the role of motility and possibly also chemotaxis in bacterial colonization of the mammalian gastrointestinal tract.

Anaerobiosis↗
PubMed1983

Characterization of Lactobacillus sp. strain 100-37 from the murine gastrointestinal tract: ecology, plasmid content, and antagonistic activity toward Clostridium ramosum H1.

A gram-positive, nonsporulating, microaerophilic rod that had two colonial variants was obtained during a study in which anaerobic bacteria were isolated from murine gastrointestinal tracts and screened for cryptic plasmids. The rod (both colonial variants) was identified as a Lactobacillus sp. (strain 100-37) by selective media, gas chromatography, and biochemical tests. In monoassociated, ex-germfree mice, the bacterium colonized the gastrointestinal tract and formed a thick, continuous layer on the keratinized squamous epithelium of the nonsecreting portion of the stomach. When lysate preparations of both colonial variants were electrophoresed in agarose gels, two bands which stained with ethidium bromide were detected with each lysate. When the DNA preparations were exposed to UV light, the lower ethidium bromide band gradually disappeared while the top band became either broader or more intense. The approximate size of the lower band was 2.2 megadaltons, as determined by comparison with plasmid molecular weight standards. In a search for phenotypes which could be encoded by the cryptic 2.2-megadalton plasmid, we detected an antagonistic activity toward an obligate anaerobe isolated from mouse feces, Clostridium ramosum H1. The antagonistic factor was precipitated with (NH4)2SO4 (70% saturation) from supernatant solutions of broth cultures of strain 100-37. The factor was not inducible with mitomycin C or UV light, but was stable in flowing steam for up to 50 min, and in buffers of pHs over a range of 1.6 to 6.8. It was nondialyzable and inactivated by trypsin and papain.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Growth and endocrine function after treatment for medulloblastoma.

Children with medulloblastoma in Bristol are treated surgically and with craniospinal irradiation, and in some cases chemotherapy. Thirteen medium or long term survivors were investigated to determine their growth and endocrine function. Their rate of growth was considerably reduced through the first year of their illness and after spinal irradiation spinal growth was poor. Nine children developed growth hormone deficiency. They were clinically euthyroid but 7 had raised basal thyroid stimulating hormone values. Gonadal function was abnormal in all but the youngest child. The rate of survival is increasing in children with medulloblastoma but this is associated with appreciable endocrine abnormalities. Some of these problems are present shortly after treatment ends but others may develop later and long term surveillance is therefore essential.

Adolescent↗
PubMed1983

Mechanisms by which indigenous microorganisms colonize gastrointestinal epithelial surfaces.

Indigenous microorganisms are known to associate with epithelial surfaces in the gastrointestinal tracts of birds and mammals of many species. In general, the mechanisms by which microorganisms associate with the epithelia are poorly understood. In some cases, in associating with epithelial surfaces, the microbial species involved undoubtedly colonize (i. e., multiply on) them. Some examples of such microorganisms are strains of certain Lactobacillus, and Candida (Torulopsis) species that associate with gastric surfaces, and strains of segmented, filamentous and of oxygen-intolerant anaerobic bacteria of numerous species that associate with intestinal surfaces in mice and rats. Several properties of the microbial cells involved may be important for them to be able to colonize epithelial habitats. Some such properties are a capacity for the cells to adhere to structures on the epithelium, or to be motile and able to move into the mucous gel present on most gastrointestinal surfaces. In addition, microorganisms that can colonize surface microhabitats on gastric or intestinal epithelia must be able to thrive in the environments and nutritional circumstances found in such habitats. In this respect, a capacity to multiply well in environments containing high concentrations of hydrogen ion is important for microbial cells to be able to colonize gastric surfaces, while a capacity enzymatically to digest mucinous glycoproteins and use the degradation products as carbon, energy and nitrogen sources may be important for microorganisms to be able to colonize most gastric or epithelial surfaces. These and related issues are examined in this paper.

Animals↗