Search PubMed⌕ Search

Biomedical subjects

J Thomas

Publications and source records attributed to J Thomas.

At least 577 records · Page 32Linked to original sources
PubMed1988

Failure of the cold pressor test to predict hypertension in black physicians: the Meharry Cohort Study.

As part of a longitudinal study of precursors for hypertension and atherosclerosis in a cohort of 315 black physicians, the predictive values of cold pressor reactivity were assessed. At initial evaluation, cold pressor tests were performed on all members of the cohort. At the 23- to 30- year follow-up, the participants were again examined and tho cumulative incidence of hypertension was analyzed by the Kaplan-Meier curves in relationship to cold pressor reactivity. The relationship between follow-up hypertension status and baseline cold pressor reactivity was also examined in a logistic regression analysis in which other potential confounders were controlled.The cold pressor test had no value in predicting the occurrence of primary hypertension.

Black People↗
PubMed1988

Type A behavior and black physicians: the Meharry Cohort Study.

A group of 261 black, male physicians was examined for the prevalence of Type A behavior and other sociomedical correlates.Type A behavior, as measured by the Jenkins Activity Survey (JAS), was collected together with type of practice specialty, blood pressure, weight, and height. Type A behavior tended to vary by physician practice specialty. The job involvement subscale correlated significantly with blood pressure but total JAS and other JAS subscale measurements did not. The job-involvement relationship with blood pressure parallels James's finding in lower socioeconomic status blacks. Type A behavior was not found to be related to hypertension but did tend to favor leanness.

Black or African American↗
PubMed1987

Structure of microtubules with reduced hydration. Comparison of results from X-ray diffraction and electron microscopy.

A recent model for the structure of microtubules is used to interpret X-ray fiber diffraction patterns from microtubules, obtained under various conditions. The results suggest that tubulin may undergo conformational changes under conditions of reduced water-activity. Such changes could account for some of the differences in the structure of tubulin as determined by electron microscopy and X-ray diffraction.

Microscopy, Electron↗
PubMed1987

Precursors of hypertension in black compared to white medical students.

Data were collected on 433 black medical students at Meharry Medical College (MMC) and 573 white medical students at The Johns Hopkins University School of Medicine (JHMS) during the period of 1958 through 1965 consisting of baseline measurement of some possible precursors of hypertension. Similar methods were employed in both cohorts. Comparison as to prevalence and significance of hypertension precursors revealed the following: Black males had significantly higher casual and resting blood pressures than whites (p less than 0.01); and higher mean changes in blood pressure following the cold pressor test. White males had a significantly higher mean change in heart rate following cold pressor test (p less than 0.01). Upon exercise black males had significantly higher mean change in blood pressure and heart rate (p less than 0.01). There appears to be more blood pressure lability in blacks as indicated by higher mean SBP + DBP changes following the cold pressor test, and by mean pulse pressure level at peak exercise. The difference in blood pressure lability observed between blacks and whites in young adulthood may be one of the earliest identifiers of later differences in the incidence of hypertension. However, of even more importance is the difference in blood pressure levels between the two groups, though both are normotensive.

Adult↗
PubMed1987

Magnetic resonance imaging in the diagnosis of disc degeneration: correlation with discography.

One hundred and one disc levels in 36 patients with low-back pain were studied with magnetic resonance imaging (MRI) (T2-weighted) sagittal images and conventional roentgenographic discography to detect early disc degeneration. Thirty-nine discs also were evaluated after discography with roentgenographic CT MRI findings were compared with discography results. MRI was 99% accurate in predicting normality or abnormality as determined by discography. Changes in disc signal on MRI accurately reflected the presence or absence of degenerative changes seen on discography in patients with low-back pain. Clinically, MRI is a useful technique for detecting early disc degeneration and for assessing the affected disc level and adjacent levels in patients with low-back pain and spondylolithesis.

Adolescent↗
PubMed1987

Promotion of incompatible allograft acceptance in rhesus monkeys given posttransplant antithymocyte globulin and donor bone marrow. I. In vivo parameters and immunohistologic evidence suggesting microchimerism.

This report extends previous studies demonstrating that prolonged acceptance of incompatible kidney allografts in rhesus monkeys can be achieved by a short recipient rabbit antithymocyte globulin (RATG) treatment course followed by donor bone marrow infusion on day 12 without a requirement for chronic immunosuppression. Serial studies of antilymphocyte cyctotoxic antibody in recipients' sera following RATG injections showed pan-lymphocyte-reactive antibody present until day 10 posttransplant. On days 11 and 12, pan-lymphocyte-reactive antibody was no longer detectable, but cytotoxic antibody specific for mature T cells remained in recipients' sera. These findings might explain the critical time relationship between antithymocyte globulin treatment and donor bone marrow infusion, and further suggest that the tolerance-promoting cell in donor bone marrow is not a mature T cell, but rather a pre-T or a non-T cell. Finally, it was found that this treatment protocol resulted in development of lymphoid nodules in the transplanted kidney that express a CD8-positive, FcIgG-receptor-positive phenotype and appear to be of donor origin. The possibility of a veto cell type of mechanism is discussed as an explanation for the promotion of allograft acceptance in this model.

Animals↗
PubMed1987

Lymphocyte subsets in the neonates of preeclamptic mothers.

With the aid of specific monoclonal antibodies, indirect immunofluorescence, and flow cytometry, peripheral blood lymphocyte populations were studied in 12 preeclamptic mothers and compared with those of ten normal patients at term. As well, lymphocyte subsets from newborns of these preeclamptic mothers and ten normal patients at term were studied. Lymphocytes were labelled with murine monoclonal antibodies directed against T cells and subsets of helper cells, suppressor/cytotoxic cells and natural killer cells. Cord blood lymphocytes of neonates from preeclamptic mothers showed a statistically significant reduction of total T cells, helper cells, and natural killer cells as compared to control. A significant reduction in helper/suppressor ratio was also observed. It is hypothesized that the differences in the immune system of the neonates in the preeclamptic group may be due to the stress of intrauterine malnutrition secondary to uteroplacental insufficiency.

Female↗
PubMed1987

Relationship between Sodium Influx and Salt Tolerance of Nitrogen-Fixing Cyanobacteria.

The relationship between sodium uptake and cyanobacterial salt (NaCl) tolerance has been examined in two filamentous, heterocystous, nitrogen-fixing species of Anabaena. During diazotrophic growth at neutral pH of the growth medium, Anabaena sp. strain L-31, a freshwater strain, showed threefold higher uptake of Na than Anabaena torulosa, a brackish-water strain, and was considerably less salt tolerant (50% lethal dose of NaCl, 55 mM) than the latter (50% lethal dose of NaCl, 170 mM). Alkaline pH or excess K (>25 mM) in the medium causes membrane depolarization and inhibits Na influx in both cyanobacteria (S. K. Apte and J. Thomas, Eur. J. Biochem. 154:395-401, 1986). The presence of nitrate or ammonium in the medium caused inhibition of Na influx accompanied by membrane depolarization. These experimental manipulations affecting Na uptake demonstrated a good negative correlation between Na influx and salt tolerance. All treatments which inhibited Na influx (such as alkaline pH, K above 25 mM, NO(3), and NH(4)), enhanced salt tolerance of not only the brackish-water but also the freshwater cyanobacterium. The results indicate that curtailment of Na influx, whether inherent or effected by certain environmental factors (e.g., combined nitrogen, alkaline pH), is a major mechanism of salt tolerance in cyanobacteria.

Journal Article↗
PubMed1987

Antigen-specific T-cell anergy in progressive Mycobacterium marinum infection in humans.

The cellular immune responses of 12 patients with culture-proved Mycobacterium marinum infection involving deep tissues were studied. Of the 12 patients, 11 failed to respond to M. marinum antigens. All of the patients had, however, normal blastogenic responses to concanavalin A, phytohemagglutinin, pokeweed mitogen, and the antigens tetanus toxoid and Candida albicans. In contrast, 9 of 14 healthy fishermen responded to the M. marinum antigens with significant in-vitro blastogenesis. Infection of deep tissues with M. marinum is associated with antigen-specific T-cell anergy to M. marinum antigens.

Antigens, Bacterial↗
PubMed1987

Cervical Gram stain for rapid detection of colonization with beta-streptococcus.

The group B beta-hemolytic streptococcus has been implicated in significant maternal and neonatal infections. The usual criteria for identifying the organism has been culture. A preliminary prospective study of the applicability of a simple, rapid, and readily available inexpensive screening tool, the Gram stain, was evaluated in 98 high-risk patients (premature rupture of the membranes and/or premature labor). In this selected population, cervical Gram stain was found to have a 98% negative predictive value for subsequent culture-proven group B beta-hemolytic streptococcus colonization. The sensitivity, specificity, and positive predictive values were, respectively, 93, 69, and 33%. Gram stain may be an appropriate test to assist in evaluation of group B beta-hemolytic streptococcus colonization in an at-risk population.

Female↗