Search PubMed⌕ Search

Biomedical subjects

D C Savage

Publications and source records attributed to D C Savage.

At least 73 records · Page 4Linked to original sources
PubMed1982

Influence of the indigenous microbiota on amounts of protein, DNA, and alkaline phosphatase activity extractable from epithelial cells of the small intestines of mice.

Germfree mice housed in isolators under controlled environmental and nutritional conditions were associated with an intestinal microflora. These associated animals and germfree mice drawn from the same population were used in experiments in which saline extracts of cells from the small intestine were assayed for alkaline phosphatase activity and for protein and DNA content. Epithelial cells were harvested from the intestines sequentially from the villous tips to the crypts of Lieberkühn. In all preparations, germfree animals yielded from one and one-third to one and one-half times the mass (wet weight) of cells yielded by associated mice. Likewise, for all preparations, extracts of the mass of cells from germfree mice contained more protein and DNA per milliliter than did extracts from associated animals. The ratio of the amount of extractable protein or DNA per milliliter of extract to the total wet weight of the cells in milligrams was about the same, however, for preparations from germfree and associated animals. All preparations from germfree animals yielded higher total alkaline phosphatase activities than those from associated mice. When related to the amount of DNA in the cells, the enzymatic activities were slightly but not significantly higher in preparations from germfree animals, except for preparations of cells removed from the tips of the villi. When related to the amount of protein in the extracts, the enzymatic activity (i.e., specific activity) was about the same in preparations from germfree and from associated mice, except (again) for preparations of cells removed from the tips of the villi. In the latter preparations, the specific alkaline phosphatase activities and enzymatic activities calculated relative to the amount of DNA were substantially higher for germfree animals than for mice with a microflora. Individual intestinal epithelial cells from germfree and associated animals, except those close to the villous tips, contain about the same alkaline phosphatase activity. Therefore, germfree mice must yield more activity of such microvillous enzymes than do mice with a microflora, partly because enterocytes at the tips of the villi in germfree mice contain more protein with enzymatic activity than do cells in a comparable location in mice with a microflora. In addition, the small intestines of germfree mice contain more activity of enzymes such as alkaline phosphatase than do those of associated animals because the small intestines of the former animals contain more enterocytes than do those of the latter.

Alkaline Phosphatase↗
PubMed1982

Effects of dietary fibre and exercise on mid-morning diabetic control--a controlled trial.

Twenty-one insulin-dependent diabetic children completed a trial of 4 different breakfasts, given in random order. Three diets differed in fibre content. The fourth diet contained soya beans as part (38%) of the dietary fibre source. Children collected capillary blood samples on to filter paper strips which were analysed for blood glucose content. Each morning the children were asked to exercise vigorously for an hour and to rest for an hour, resulting in comparable rest and exercise periods for each child. Mean initial blood glucose levels on the 4 diets were not significantly different. The low-fibre diet resulted in the highest blood glucose concentrations after breakfast. Blood glucose levels on the high-fibre diet did not differ from those on the medium-fibre diet. The bean diet produced the lowest mean blood glucose level and the smallest reduction in blood glucose level in the hour before lunch. All the children found the bean diet unacceptable but liked the high- and medium-fibre diets, which were as popular as the low-fibre diet. The level of prescribed exercise had no effect on the level of blood glucose. It appears that the potentially major benefits from beans are limited by their unpalatability. The more acceptable cereal fibre produces a smaller but important benefit on morning hyperglycaemia after breakfast.

Adolescent↗
PubMed1982

Impact of home blood glucose monitoring on childhood diabetes.

Ninety diabetic children each provided at least one 24-hour blood glucose profile at home using an impregnated filter paper strip. The mean 24-hour blood glucose level correlated significantly with urine control, height velocity, and Hb A1. The correlation coefficient for individual blood glucose values (r = 0.61) and for mean 24-hour blood glucose values (r = 0.73) repeated within 14 days showed an acceptable degree of reproducibility for the blood glucose profiles. Mean 24-hour blood glucose values fell significantly overall (11.4 to 9.8 mmol/l; 205 to 176 mg/100 ml) in 47 children who had repeated profiles more than 2 weeks apart. Unrecognised nocturnal hypoglycaemia (less than 3.0 mmol/l; 54 mg/100 ml) was found in 19% of children on twice-daily Semitard insulin. The study shows that children over age 7 years manage home blood glucose monitoring without difficulty. It shows that the results are reproducible and correlate with other indices of control, and that it provides a practical basis for the improvement of diabetic control.

Blood Glucose↗
PubMed1981

Influence of indigenous microbiota on amount of protein and activities of alkaline phosphatase and disaccharidases in extracts of intestinal mucosa in mice.

The protein content and the activities of alkaline phosphatase, maltase, and sucrase were measured at 0800, 1000, 1200, 1400, and 1600 in saline extracts of the proximal small bowels of germfree and of ex-germfree mice colonized with an indigenous microbiota. In extracts prepared from germfree mice, the total activities of all of the enzymes were relatively constant throughout the sampling period. Likewise, the total activity of alkaline phosphatase in extracts prepared from associated mice varied little as a function of time. By contrast, the total activities of maltase and sucrase in the extracts from these latter animals varied significantly from sample to sample. The total activity levels in extracts from germfree mice were approximately twofold greater than the levels in extracts from associated mice. The specific activities of alkaline phosphatase and sucrase did not vary from sample to sample in extracts prepared from either type of mouse. In contrast, the specific activity of maltase in extracts prepared from both germfree and associated mice differed significantly from sample to sample. The specific activities of all three enzymes were greater in extracts from germfree animals than in those from associated animals. The protein content of extracts prepared from germfree mice also was greater than that of extracts prepared from associated animals at every sampling time. The amount of protein extractable from the mucosa of the small bowels of the former animals varied significantly at different sampling times during the day, whereas the amount of protein extractable from the tracts of associated animals remained relatively constant throughout the day. The indigenous microbiota apparently stabilizes in some way the amount of protein extractable from the mucosa of the mouse small bowel.

Alkaline Phosphatase↗
PubMed1981

Transit time of epithelial cells in the small intestines of germfree mice and ex-germfree mice associated with indigenous microorganisms.

Germfree mice housed in isolators under controlled environmental and nutritional conditions were associated with an intestinal microflora. These associated animals and germfree mice drawn from the same population were tested for the rate at which the epithelial cells transited from the crypts of Lieberkuhn to the tips of the villi in their small intestines. The method for estimating the rate of transit of epithelial cells involved the use of liquid scintillation counting to determine the amount of radioactivity entering the cells while the animals were being injected with [3H]thymidine and statistical analysis of th data with a computer program developed for the purpose. As estimated by that method, the cells transited from the crypts to the villous tips in germfree mice in about 115 h and in the associated animals in about 53 h. In monoassociated mice, a strain of a Lactobacillus sp. had no effect on the transit time of the epithelial cells. A strain of Torulopsis pintolopesii stimulated uptake of 3[H]thymidine by the small bowel mucosae in mice monoassociated with the organisms for 5 weeks. In animals monoassociated with the yeast fo 3, 4, and 6 weeks, however, the radioactive compound was incorporated into the bowel mucosae to the same extent as the mucosae of germfree mice. Therefore, similarly to the Lactobacillus strain, T. pintolopesii has no obvious influence on the transit rate of small bowel epithelial cells.

Animals↗
PubMed1981

Another Colicin V phenotype: in vitro adhesion of Escherichia coli to mouse intestinal epithelium.

Two assays were designed with which isogenic laboratory strains of Escherichia coli K-12 with and without ColV plasmids were compared for their ability to adhere in vitro to mouse intestinal epithelium. In both assays, disks of intestinal tissue were exposed to bacteria. In the first, disks were homogenized and the numbers of viable bacteria adherent to them were estimated from colony counts of plates inoculated with dilutions of the homogenates. In the second, bacteria were labeled with [(14)C]aspartic acid; the number of adherent cells per disk was estimated by liquid scintillation spectrometry. Data from each assay were compared by analysis of variance. In both assays, strains bearing the ColV plasmid adhered in two- to threefold-greater numbers than isogenic strains without the plasmid. These differences were highly significant statistically. A non-colicinogenic strain free of the ColV plasmid was selected by treatment of a ColV strain with sodium dodecyl sulfate. In the radioisotopic assay, the ColV strain associated with the epithelium in significantly greater numbers than the cured derivative. A ColV strain was created by conjugation; in the radioisotopic assay this strain bound to epithelium in significantly greater numbers than the recipient strain without the plasmid. The original ColV strain, when negatively stained and examined by electron microscopy, had pili that adsorbed male-specific bacteriophage, whereas its isogenic variant without ColV did not. Some such properties, coded by the plasmid, may increase the virulence of the bacteria.

Animals↗
PubMed1981

Height and skeletal maturity in children with newly-diagnosed juvenile-onset diabetes.

Height and skeletal maturity scores (TW 2) were determined in 77 diabetic children at diagnosis and again in 48 of them after 1 to 4 years on insulin treatment. Boys, especially those of prepubertal age, were tall at onset. Girls had normal stature, but showed significant growth retardation after treatment. Skeletal maturity was appreciably advanced in both sexes at diagnosis, and on treatment returned to normal only in boys. Girls maintained their advanced skeletal maturity, resulting in an increased disparity between height and skeletal maturity. The results of this study suggest that a prediabetic metabolic abnormality may enhance skeletal maturity in children with diabetes and continues to operate in girls after treatment, despite a reduced growth rate.

Adolescent↗
PubMed1981

Effect of cyproterone acetate on adrenocortical function in children with precocious puberty.

Seven children with precocious puberty were treated with cyproterone acetate and their adrenal function studied. In each child the drug caused significant adrenal hypofunction which was secondary to adrenocorticotrophic hormone suppression. None of these children had clinical evidence of adrenal hypofunction and it is assumed that the drug has glucocorticoid-like properties. Children receiving cyproterone acetate should carry information to warn doctors of this effect since they may require steroid cover during illness.

Adrenal Cortex↗
PubMed1980

Kinetics of changes induced by indigenous microbiota in the activity levels of alkaline phosphatase and disaccharidases in small intestinal enterocytes in mice.

The concentration of protein and the activities of alkaline phosphatase, maltase, and sucrase were measured in saline extracts of the proximal small intestine of germfree and ex-germfree mice colonized with an indigenous microflora. The two populations of animals were maintained in plastic film isolators under tightly controlled environmental and nutritional conditions. Samples were taken at 0, 4, 8, 12, and 17 days and at 3, 4, 5, 6, 7, and 8 weeks after association. The activities were expressed as specific activities and as total units per segment of small intestine. Enzymatic activities expressed in both ways fluctuated considerably in the samples taken from one time to the next in animals of both types. The activities expressed as total units per segment of bowel of all three enzymes had decreased from levels in germfree animals by as early as 4 days after association. The total units of activity per segment of bowel tested continued to decrease for approximately 3 weeks in the associated animals to levels two- to fivefold lower than those of germfree animals. However, the specific activities of the three enzymes in the animals of the two types became less disparate at later sample times. This latter result is predictable because the concentration of protein extractable from the small intestines of the mice of the two types was the same at the beginning of the experiment, but by the later sampling times, the concentration of protein extractable from small bowels of ex-germfree mice was significantly lower than that from germfree mice. The fluctuations in levels of the enzymatic activities, even under controlled environmental and nutritional conditions, point to the necessity of using such conditions and a kinetic approach in studies of the effects of the microbiota on the activities of enzymes in the microvillous membranes of small bowel enterocytes. The changes in protein concentrations suggest that such activities and the amounts of protein extractable from the mucosa are influenced by different properties of the microflora. Thus, studies in which the enzymes are extracted from the entire mucosa and the activities are expressed as units per weight of extractable protein may give misleading results concerning the influence of the microbiota on the enterocyte membranes.

Alkaline Phosphatase↗
PubMed1979

Introduction to mechanisms of association of indigenous microbes.

Indigenous microorganisms of numerous types associate with epithelial surfaces in the gastrointestinal tracts of mammals and birds. Some of the microbial types, e.g., Lactobacillus sp. in the stomachs of laboratory rodents, adhere to a surface without altering it ultrastructurely. In such cases, the adherence is mediated undoubtedly by macromolecules on the bacterial surfaces, possibly polysaccharides in most cases, interacting in specific ways with receptor macromolecules on the epithelial surface. Other microbial types that associate with epithelial surfaces without altering them ultrastructurally, e.g., Clostridium 109-2 in the mouse large bowel, may adhere to the surface only weakly or not at all, and maintain the association because they are motile and attracted to the epithelium by chemotactic substances. Microbial types that alter the ultrastructure of the epithelial cells to which they attach interact intimately with the membranes of the epithelial cells. In such cases, the microbes have specialized segments or ends for adhering to the membranes, and probably elaborate systems for stabilizing the membranes and cytoplasm at the site in the epithelial cell to which they attach. Some such organisms may have evolved unique reproductive mechanisms to maintain their populations on the epithelial surface.

Adhesiveness↗
PubMed1979

Determinants in microbial colonization of the murine gastrointestinal tract: pH, temperature, and energy-yielding metabolism of Torulopsis pintolopesii.

Torulopsis pintolopesii is an indigenous yeast that colonizes the secreting epithelia in the stomachs of mice and rats. A wild-type strain of this microbe was isolated and identified. To attempt to learn characteristics of the yeast that are advantageous to it in colonizing its natural habitat in vivo, we examined some aspects of its nutrition and energy-yielding metabolism and some environmental conditions that influence its growth in vitro. The yeast appeared to be limited in the compounds it can utilize as carbon and nitrogen sources. It grew best at 37 degrees C and did not grow at 23 or 43 degrees C. It grew optimally at neutral pH but could grow aerobically at pH values as low as 2.0 and anaerobically at pH values as low as 3.4. As assessed by measurements of growth rates and yield coefficients, it grew better aerobically than anaerobically. When grown aerobically, it had a cyanide-sensitive system for taking up O(2) and tested positively for cytochrome c oxidase activity. A petite mutant strain isolated from the wild-type strain had a growth rate and yield coefficient when incubated aerobically that were essentially the same as those of the wild-type parent grown anaerobically. Likewise similar to the wild-type parent grown anaerobically, the petite strain, though incubated aerobically, did not take up O(2). Yeast-free mice associated with either the wild-type or the petite mutant strain were colonized at essentially the same rates and to similar final population levels by both strains. The yeast's capacity to respire may be of little advantage to it in its natural environment. By contrast, its abilities to grow best at 37 degrees C and to grow at low pH values are undoubtedly advantageous characteristics in this respect. The limitations in its carbon and nitrogen nutrition are difficult to evaluate as ecological factors in its colonization of the natural habitat.

Animals↗
PubMed1979

Microbial interference and colonization of the murine gastrointestinal tract by Listeria monocytogenes.

Two strains of Listeria monocytogenes, one that formed smooth colonies on agar surfaces and a varient of it that formed rough colonies, colonized the gastrointestinal tracts of germfree mice. Within 24 h after mice were inoculated orally with about 100 bacteria, the population levels per gram (wet weight) of tissue of both strains were 10(5) to 10(7) in the stomach and ileum and 10(8) to 10(9) in the cecum and colon, respectively. As detected in Gram-stained histological sections, in such gnotobiotes, the bacteria colonized the lumen in all areas of the tract and much of the mucus layer on the epithelial surface in the proximal colon. The strain that formed smooth colonies did not colonize the tracts of specific-pathogen-free mice, but did colonize, to the same levels as in germfree mice, the stomachs and bowels of ex-germfree mice previously associated with two members of the indigenous flora (Bacteroides and Clostridium). In the latter animals, however, the listeria did not form layers on the colonic epithelium as efficiently as they did in monoassociated gnotobiotes.

Animals↗
PubMed1979

Ecological determinants in microbial colonization of the murine gastrointestinal tract: adherence of Torulopsis pintolopesii to epithelial surfaces.

Torulopsis pintolopesii is a yeast indigenous to the gastrointestinal tracts of conventional mice and rats from many colonies. In such natively colonized animals, the organism forms layers on the surface of the epithelium in the secreting portion of the stomach and can be cultured from all areas of the gastrointestinal tract. When given in water or food to germfree mice or specific pathogen-free mice possessing an indigenous microbiota free of yeast, T. pintolopesii also can be cultured from all areas of the tract at population levels ranging from 10(5) to 10(8) cells per g (wet weight). Likewise, as in its native hosts, the organism forms layers on gastric surfaces in the associated animals. The layers form on the secreting surface in both the specific pathogen-free and monoassociated ex-germfree mice. In the latter animal, however, a layer of yeast also forms on the nonsecreting gastric surface. In tests of its capacity to adhere to gastrointestinal surfaces in vitro, the organism adheres to epithelia from all areas of the mouse tract. These findings support an hypothesis that the capacity of T. pintolopesii to adhere to epithelial surfaces may be only one determinant influencing it to form layers on the gastric secreting surface in its native hosts.

Animals↗
PubMed1979

Models for study of the specificity by which indigenous lactobacilli adhere to murine gastric epithelia.

A Lactobacillus strain isolated from a mouse (indigenous) and another strain isolated from swine feces (nonindigenous) were compared in two model systems for their ability to adhere in vitro and in vivo to keratinizing squamous and columnar epithelia of mouse stomachs. In one model, stomachs dissected from specific-pathogen-free or germfree mice were injected with suspensions of lactobacilli labeled with [(3)H]thymidine and incubated at 37 degrees C. Thereafter, the non-secreting and secreting tissues were separated and washed vigorously. The radioactivity remaining with each tissue was counted by liquid scintillation spectrometry. When the radioactivity remaining with these tissues ranged between 500 and 100,000 cpm, the calculated radioactivity (disintegrations per minute) was related linearly to the number of lactobacilli adhering to the tissue. The estimate of the number of bacteria adherent to the tissue was not influenced significantly by artifacts in the techniques used. In this model, both Lactobacillus strains adhered in equally high numbers to both types of epithelial surfaces from stomachs from germfree mice. In contrast, in the second model, in which germfree mice were monoassociated with one or the other of the Lactobacillus strains, only the strain indigenous to the mouse formed dense layers on the epithelia of the nonsecreting portions of the stomachs, although both strains maintained high population levels throughout the gastrointestinal tracts of the animals. The capacity to adhere to the mucosal surface is undoubtedly necessary for lactobacilli to colonize gastric epithelia in mice. Our findings suggest, however, that nutritional or environmental conditions dictate whether particular Lactobacillus strains can colonize particular surfaces in the stomachs of living animals.

Animals↗