Search PubMed⌕ Search

Biomedical subjects

R L Montgomery

Publications and source records attributed to R L Montgomery.

At least 19 recordsLinked to original sources
PubMed1991

Isoniazid as preventive therapy in HIV-infected intravenous drug abusers. A decision analysis.

Tuberculin skin testing is a notoriously poor marker of tuberculosis infection in patients who are serologically positive for the human immunodeficiency virus. A decision analysis was performed to determine if and when isoniazid should be prescribed to prevent tuberculosis in these patients. The decision was analyzed for an intravenous drug abuser who may have been anergic, while tuberculin test status, race, and gender were varied. The assumptions and parameter estimates selected for this investigation represent a highly conservative vantage point opposing the use of isoniazid as a preventive therapy. Nevertheless, results showed a benefit from the use of isoniazid as a preventive therapy for all groups, even without tuberculin testing, except tuberculin-negative black women. This benefit of isoniazid therapy increased patient life expectancy as much as 285 days. Further, the decisions continue to favor prescribing isoniazid even when the suspected incidence of tuberculosis infection falls as low as 3% to 8%. Tuberculin testing appears important primarily for black women, since those who have negative tuberculin skin tests may not be candidates for isoniazid therapy.

Adult↗
PubMed1991

Regulation of ornithine decarboxylase mRNA by phorbol esters and insulin in normal and C-kinase-deficient rat hepatoma cells.

Tumor-promoting phorbol esters and insulin produce similar effects in Reuber H35 rat hepatoma cell proliferation, including increased ornithine decarboxylase (ODC) enzyme activity, DNA synthesis, and mitogenesis. We investigated ODC mRNA accumulation in cells treated with either insulin or 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Both agents caused rapid accumulation of ODC mRNA: for TPA, it was maximal 3 hr after treatment (4-6-fold greater than control cells) and returned quickly to control levels; for insulin, it was significantly longer, continuing to increase for at least 6 hr. Simultaneous treatment with TPA and insulin led to additive effects on ODC mRNA. Induction of ODC by TPA was blocked by down-regulation or inhibition of protein kinase C (PKC), consistent with a PKC-mediated mechanism. In contrast, PKC down-regulation had little effect on ODC induction by insulin. Furthermore, although both agents stimulated ribosomal S6 protein phosphorylation in cells containing normal amounts of PKC, the response to TPA was abolished in PKC-depleted cells; the effect of insulin was only slightly inhibited. TPA caused a rapid redistribution of essentially all of the PKC activity from the cytosolic to the membrane fraction of the cells, whereas insulin had no effect on PKC distribution. These results suggest that although insulin and TPA share some common cytoplasmic signalling pathways, their effects on phosphorylation of nuclear proteins and transcription of ODC may be mediated by distinct factors.

Animals↗
PubMed1988

Social support, perceptions of attractiveness, weight, and the CPI in socially anxious males and females.

To see how socially anxious people function in a number of domains, Watson and Friend's (1969) Social Avoidance and Distress Scale (SAD) was administered to 101 undergraduates along with the California Personality Inventory (CPI) and the Psychosocial Support Inventory (PSI), a measure of social support. Additionally, a perceived attractiveness measure and various measures related to being overweight were taken. SAD scores correlated significantly in a negative direction with 13 of the 18 CPI scales, and those with high SAD scores had poorer social support networks. High SAD scores also were related to the perception of being overweight, but not to perceived physical attractiveness or to actually being overweight. Gender differences showed that females had more intimate social interactions and that socially anxious females relied more on their family for social support than did other people. Overall, the results suggested that the socially anxious person may have deficits in a variety of personal and interpersonal domains.

Adult↗
PubMed1987

Demography and pathology of an urban slave population from New Orleans.

Twenty-nine skeletons from the first cemetery in New Orleans provide significant new information about urban slavery in America. Dating as early as 1720 and used perhaps as late as 1810, the cemetery provided an identifiable sample of two whites, 13 blacks, one individual of possible Indian-white ancestry, and two possibly mulatto individuals. Numerous skeletal and dental lesions were noted in the series, and historical information was used in conjunction with the physical data to draw conclusions about rates and patterns of mortality. Pathological changes indicate that the cemetery contained individuals representing two slave occupational groups, house servants and laborers. This research provides information in the expanding area of Afro-American biohistorical research.

Black or African American↗
PubMed1978

An X-ray diffraction comparison of myelins from the human nervous system.

Earlier small-angle X-ray diffraction studies have indicated that central and peripheral nerve myelins may be significantly different structurally, although relatively few examples for each system and for individual species have been examined. In order to understand better the intra- and inter-system relationships, this study has developed more extensive information for a single species: six cases centrally and ten peripherally, featuring cranial nerves and a few others of the human nervous system. Peripheral myelin spacings (membrane pair thicknesses) are relatively similar, 184.4 +/- 1.40 A, and the ratios of diffraction peak height intensities of the second to fourth orders are also closely bunched: 1.85 +/- 0.216. Central myelin spacings and intensity ratios are distinctly different and more variable: spacings 160.3-165.8 A and intensity ratios 2.81-4.46. It appears that within a given species or between closely related (e.g., mammalian) species peripheral myelins possess relatively invariant structures, though significant spacing declines are encountered for both systems as phylogenetic relationships become more distant. The observed greater variability of CNS structures within a single species may correspond to known compositional differences between CNS regions or result from observational difficulties. In any case there is a marked discontinuity between the myelin structures of CNS and PNS nerves.

Adolescent↗