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Biomedical subjects

R M Stewart

Publications and source records attributed to R M Stewart.

At least 55 records · Page 3Linked to original sources
PubMed1991

Effect of dietary ethanol on gallbladder absorption and cholesterol gallstone formation in the prairie dog.

Dietary ethanol has been reported to protect against cholesterol gallstone formation. Because enhanced gallbladder absorption of water is important in cholesterol cholelithiasis, we examined the hypothesis that ethanol acts by inhibiting the absorptive function of the gallbladder. Eighteen adult male prairie dogs were fed a lithogenic liquid diet containing 0.4% cholesterol. Half of the animals received 30% of total calories as ethanol, whereas their pair-fed controls received equicaloric amounts of maltose-dextrin. After 3 months, the gallbladders were inspected for gallstones and crystals, and gallbladder and hepatic bile were analyzed. Cholesterol stones and crystals were present in all nine controls. None of the alcohol-fed animals had stones, but four had cholesterol crystals. Gallbladder cholesterol, phospholipids, and total calcium were significantly decreased in alcohol-fed animals. In both gallbladder and hepatic bile, the cholesterol saturation index was significantly lower in alcohol-fed animals, as was the ratio of trihydroxy to dihydroxy bile salts. The ethanol-supplemented diet produced a significant decrease in the absorption of water by the gallbladder as indicated by changes in the gallbladder bile to hepatic bile ratios of the total bile salt concentration (7.29 +/- 1.25 versus 3.84 +/- 0.56; p less than 0.05) and the total calcium (3.37 +/- 0.24 versus 2.43 +/- 0.29; p less than 0.05). These findings indicate that the protective effect of ethanol may be related to its ability both to inhibit gallbladder absorption of water and to alter the composition of biliary lipids.

Absorption↗
PubMed1991

Linkage of loci associated with two pigment mutations on mouse chromosome 13.

Progeny from one intra- and two inter-specific backcrosses between divergent strains of mice were typed to map multiple markers in relation to two pigment mutations on mouse chromosome 13, beige (bg) and pearl (pe). Both recessive mutants on a C57BL/6J background were crossed separately with laboratory strain PAC (M. domesticus) and the partially inbred M. musculus stock PWK. The intra- and inter-specific F1 hybrids were backcrossed to the C57BL/6J parental strain and DNA was prepared from progeny. Restriction fragment length polymorphisms were used to follow the segregation of alleles in the backcross offspring at loci identified with molecular probes. The linkage analysis defines the association between the bg and pe loci and the loci for the T-cell receptor gamma-chain gene (Tcrg), the spermatocyte specific histone gene (Hist1), the prolactin gene (Prl), the Friend murine leukaemia virus integration site 1 (Fim-1), the murine Hanukuh Factor gene (Muhf/Ctla-3) and the dihydrofolate reductase gene (Dhfr). This data confirms results of prior chromosomal mapping studies utilizing bg as an anchor locus, and provides previously unreported information defining the localization of the prolactin gene on mouse chromosome 13. The relationship of multiple loci in relation to pe is similarly defined. These results may help facilitate localization of the genes responsible for two human syndromes homologous with bg and pe, Chediak-Higashi syndrome and Hermansky-Pudlak syndrome.

Animals↗
PubMed1990

Region-specific neural induction of an engrailed protein by anterior notochord in Xenopus.

Anterior-specific neural induction can be assayed by means of an antibody that recognizes the Xenopus homeobox-containing protein En-2. The En-2 antigen is an excellent early marker, since it is present as a discrete band in the anterior neural plate of neurula embryos. Regional induction was assayed by combining dorsal mesoderm with competent ectoderm. Anterior notochord from the early neurula induced En-2 frequently, while posterior notochord induced En-2 less frequently. Presumptive somitic mesoderm and presumptive head mesoderm, though they induced neural tissue, were not strong inducers of En-2. Thus, anterior notochord may be the primary mesodermal tissue responsible for the patterning of the anterior neural plate.

Animals↗
PubMed1990

The anterior extent of dorsal development of the Xenopus embryonic axis depends on the quantity of organizer in the late blastula.

In amphibian gastrulae, the cell population of the organizer region of the marginal zone (MZ) establishes morphogenesis and patterning within itself and within surrounding regions of the MZ, presumptive neurectoderm, and archenteron roof. We have tested the effects on pattern of reducing the amount of organizer region by recombining halves of Xenopus laevis late blastulae cut at different angles from the bilateral plane. When regions within 30 degrees of the dorsal midline are excluded from recombinants, ventralized embryos develop lacking the entire anterior-posterior sequence of dorsal structures, suggesting that the organizer is only 60 degrees wide (centered on the dorsal midline) at the late blastula stage. As more and more dorsal MZ (organizer) is included in the recombinant, progressively more anterior dorsal structures are formed. In all cases, when any dorsal structures are missing they are deleted serially from the anterior end. Thus, we suggest that the amount (lateral width) of the organizer in the MZ determines the anterior extent of dorsal development.

Animals↗
PubMed1990

Attributions for rapid or slow recovery from sports injuries.

Sport participants (n = 276) stated the most likely cause of rapid or slow recovery from injury and rated that causal factor along several dimensions. Examination of the open-ended responses suggested that four general types of attributions were utilized by the athletes: personal factors, injury-related factors, treatment-related factors, and situational factors. Analysis of dimensional ratings indicated: (a) causes of slow recovery were consistently perceived as less stable, controllable, global, and intentional than causes of rapid recovery; (b) causes of slow recovery were sometimes perceived as more internal than causes of rapid recovery; and (c) physical self-esteem interacted with gender to influence dimensional ratings of the attributions. These findings were discussed in relation to the motivational significance of causal interpretations during recovery and in relation to the model of stress and athletic injury presented by Andersen and Williams (1988).

Adult↗
PubMed1988

An outcome study of Gamblers Anonymous.

Retrospective and prospective studies of a total sample of 232 attenders at groups of Gamblers Anonymous suggest that total abstinence from gambling was maintained by 8% of all comers at one year from first attendance and by 7% at two years.

Alcoholics Anonymous↗
PubMed1987

The incidence and risk of early postoperative small bowel obstruction. A cohort study.

Early postoperative small bowel obstruction is a rare (0.69 percent incidence) but serious postoperative complication with a relatively high mortality rate (17.8 percent). Operations performed below the transverse mesocolon impose an increased risk, whereas those limited to the upper abdomen are virtually free of risk. The clinical picture of a patient who initially manifests a return of gut function and advances to a diet, but then has loss of bowel function with distention and pain is most characteristic of early postoperative small bowel obstruction. Any patient in the high-risk group demonstrating this clinical picture should be presumed to have a mechanical small bowel obstruction, and early operation should be considered.

Abdomen↗
PubMed1984

Evoked potentials in Huntington's disease. A comparative and longitudinal study.

Pattern-reversal visual (PRVEPs), brain-stem auditory (BAEPs), and somatosensory (SSEPs) evoked potentials were studied in 12 patients with Huntington's disease (HD) and were repeated in eight at one and two years. The mean cortical SSEP amplitude was decreased compared with that of age-matched controls, with a trend of decreasing amplitude with increasing duration and severity of illness. The SSEP latency was not significantly different from that of controls. The PRVEPs and BAEPs were normal. The serial studies showed a progressive decrease in amplitude of the SSEP over a two-year period. These neurophysiological findings may reflect the pathological involvement of the thalamus reported for HD. While evoked potentials are not of use in individual case diagnosis, the SSEP may be an objective physiological method for following the course of the disease in HD and the effects of therapeutic intervention in patient populations.

Aged↗
PubMed1983

Dynamic membrane studies in individuals at risk for Huntington's disease.

Lymphocyte plasma membrane dynamics were studied by energy-transfer polarization in twenty-three neurologically normal individuals at-risk for Huntington's disease (HD). The results were compared to 10 normal controls and 10 known HD patients. The normal and HD subjects segregated into two distinct groups. The at-risk group had findings distributed along a continuum with values similar to known HD patients or to normal controls. These findings suggest that further studies of membrane dynamics will contribute to understanding the molecular defect in HD and to the development of a potential molecular marker.

Adult↗
PubMed1983

Defining neurosurgical and neurological nursing practice: establishing our clinical parameters, part I.

We have examined the education and practice roles of various professional and allied health personnel necessary for providing optimal care to a specialized group of patients, in this case, the neurosurgical/neurological patient group. One needs to investigate these factors in order to plan for effective economic utilization of such personnel in the health care system. The primary goal of all health care providers is quality patient care services, yet secondary concerns cannot be overlooked if we are to accomplish this ultimate goal. Prohibitive health care costs for those we serve and escalating educational costs to become competent to render such services mandate that we choose the most advantageous use of available resource personnel. Placing professionals in appropriate positions which allow them to apply their education and clinical strengths in the care of patients will not only promote excellence in patient care but also excellence in each professional practice role.

Education, Nursing↗