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Biomedical subjects

W D Johnson

Publications and source records attributed to W D Johnson.

At least 199 records · Page 11Linked to original sources
PubMed1980

Prevalence of latent prostate carcinoma in two U.S. populations.

The prevalence of latent prostate carcinoma, the suspected precursor of invasive carcinoma, was studied in 500 autopsy specimens from New Orleans, Louisiana, and found to be similar in both whites and blacks. The tumors were subdivided into latent infiltrative type (LIT) and latent noninfiltrative type tumor was measured by photographic techniques. A good correlation between size and histology was found: The mean size of LIT tumors was significanty greater than that of LNT tumors. Age-versus-size plots revealed a subset of large LIT lesions in blacks that was not found among whites of the same ages. This subset may account for the excess of invasive carcinomas in blacks. These results suggest that many latent carcinomas lack promotional stimuli to become invasive.

Adult↗
PubMed1980

Prosthetic valve endocarditis.

The diagnosis, therapy, and complications of prosthetic valve endocarditis (PVE) in 48 patients seen between 1962 and 1978 are reviewed. Staphylococcus epidermidis and diphtheroids were the most common causes of both early and late PVE. These microorganisms were frequently resistant to the penicillins and cephalosporins but were uniformly sensitive to vancomycin. The mortality rate in this series was 69%, with 20% of the deaths attributed to central nervous system emboli and the remainder to cardiac causes. The mortality rate exceeded 75% in patients with any of the following findings: aortic valve infection, nonstreptococcal infecting microorganism, new or increased regurgitant murmurs, or significant congestive heart failure (CHF). The mortality rate was lowest in streptococcal PVE (29%) and in mitral valve PVE (49%). The unacceptably high mortality rate suggests that early replacement of infected prostheses should be considered in all patients except those with uncomplicated streptoccal or mitral valve PVE.

Bacterial Infections↗
PubMed1980

Improvement in left ventricular function after myocardial revascularization: assessment by first-pass rest and exercise nuclear angiography.

Thirty-six patients with coronary artery disease were studied by first-pass radionuclide angiography to assess the effects of myocardial revascularization on exercise-induced myocardial ischemia. The radionuclide studies were performed in the 30 degree right anterior ablique position, at rest and during exercise, 1 to 3 days preoperatively and 10 to 14 days postoperatively. The mean population age was 53 years; the mean number of grafts placed was 4.0 per patient. Fifteen normal male volunteers were tested by rest and exercise radionuclide angiography to serve as normal control subjects. In all exercise radionuclide studies, progressive upright bicycle exercise was performed to symptoms of fatigue, dyspnea, or chest pain. The parameters of ejection fraction (EF), end-diastolic volume (EDV), and regional wall motion (RWM) were determined. Twenty-nine of the 36 patients had postoperative coronary arteriography that was correlated with radionuclide determinations. The results showed that in the normal subjects with maximal exercise the mean EF rose, the mean EDV increased 19%, and there was no exercise-induced regional wall motion dysfunction (ERWMD). In the patients with coronary artery disease prior to operation, the mean EF fell significantly, the mean EDV rose 24%, and 26 of 36 patients had ERWMD. After operation, the mean EF of the group rose, the EDV increased only 15%, and only two of 36 patients continued to show ERWMD. Of the eight patients who demonstrated on abnormal response postoperatively, seven had what was considered to be inadequate revascularization, and in one there was no explanation. The data demonstrate that myocardial revascularization does improve ventricular function by abolishing exercise-induced evidence of ischemia (decreased EF, increased EDV, and ERWMD) as assessed by radionuclide angiography. Failure to abolish the exercise-induced functional instability suggests incomplete revascularization.

Adult↗
PubMed1979

Fatty acid composition of human adipose tissue from two anatomical sites in a biracial community.

This report describes the age-race specific distribution of fatty acids in samples of adipose tissue taken from both the perirenal and buttock areas of 406 men autopsied in a community pathology study. This analysis of fatty acid composition of adipose tissue is part of a comprehensive investigation of atherosclerosis and coronary heart disease in a community setting. The findings from analysis of fatty acids are expressed as mass percentage of all fatty acids in adipose tissue triglyceride. For each age-site subgroup, white men tended to have higher mean percentages of myristic acid and palmitoleic acid than did black men. The converse was found for stearic acid. In the younger age groups only, the whites showed a higher mean percentage of linoleic acid than the blacks in adipose tissue from both sites. Age was associated with a decrease in mean percentage of stearic acid and an increase in mean percentage of oleic acid and palmitoleic acid in both races. The older age group had a lower mean percentage of linoleic acid than the younger age groups. The mean percentages of myristic, palmitic, and stearic acids were higher in perirenal tissue, while the mean percentages of palmitoleic and oleic acids were higher in buttock adipose tissue in both races.

Adipose Tissue↗
PubMed1978

Use of intra-aortic balloon pumping (IABP) in clinical cardiac surgery and management of patients with IABP.

One hundred thirty eight patients were reviewed which required IABP assist. Sixty nine (84 per cent) of 82 patients who had been able to come off cardiopulmonary bypass despite increasing pharmacologic support survived operation and 56 patients (68 per cent) discharged hospital. Twenty three (75 per cent) of 31 patients who took for elective coronary artery surgery as extremely high risk because of extensive three vessel coronary artery disease and severely compromised left ventricular function discharged hospital. In summary, hospital death was 35 per cent, late death 12 per cent and long term survivors 54 per cent. Severe complication concerned with inserting balloon catheter occurred in two cases (1.4 per cent) which were abdominal aortic dissection and laceration of iliac artery. At the present time, the primary indication for IABP is in assistance of the open heart surgical patient. Thre are three important factors in successfully managing the patients with IABP. First, begin IABP assist as soon as possible if indicated. Second, keep an adequate circulating volume with mean left atrial pressure being maintained around 20 mmHg and cardiac index at 2.1 L/min./M or greater. Third, improve the peripheral vascular circulation, which might need peripheral vasodilator.

Assisted Circulation↗
PubMed1978

Vancomycin therapy of bacterial endocarditis.

Fifteen patients with bacterial endocarditis were treated with vancomycin between 1967 and 1976. The indications for vancomycin therapy were penicillin-cephalosporin allergy in six patients, antibiotic resistant bacteria in six, initial therapy in one and culture-negative endocarditis in two. The causative microorganisms were Staph. epidermidis (four patients), Staph. aureus (two patients), diphtheroids (four patients), viridans streptococci (two patients) and enterococci (one patient). Minimum inhibitory concentrations of vancomycin for these organisms ranged from 0.8 to 3.1 micrograms/ml. The patients received vancomycin for two to 10 weeks (mean five weeks). Cure was achieved in 13 patients, including six with prosthetic valve endocarditis (PVE). Two patients had a relapse of PVE and cultures of blood or heart valve were positive within two months of vancomycin therapy. Vancomycin serum levels did not exceed 50 micrograms/ml, and no serious drug toxicity was encountered in any patient. Three patients had minimal audiogram changes beyond the social hearing range. One patient had mild phlebitis and a rash, and one patient had a transient leukopenia. Vancomycin is an effective nontoxic antibiotic in patients with endocarditis when penicillin or cephalosporin therapy is not appropriate.

Adult↗
PubMed1978

A computer program for the generalized chi-square analysis of competing risks grouped survival data (CRISCAT).

CRISCAT is a computer program for the analysis of grouped survival data with competing risks via weighted least squares methods. Competing risks adjustments are obtained from general matrix operations using many of the strategies employed in a previously developed program (GENCAT) for multivariate categorical data. CRISCAT computes survival rates at several time points for multiple causes of failure, where each rate is adjusted for other causes in the sense that failure due to thes other causes has been eliminated as a risk. The program can generate functions of the adjusted survival rates, to which asymptotic regression models may be fit. CRISCAT yields test statistics for hypotheses involving either these functions or estimated model parameters. Thus, this computational algorithm links competing risks theory to linear models methods for contingency table analysis and provides a unified approach to estimation and hypothesis testing of functions involving competing risks adjusted rates.

Actuarial Analysis↗
PubMed1978

Dehydroretronecine-induced skin tumors in mice.

Female Swiss mice susceptible to skin tumors received 6 sc injections and/or topical applications of dehydroretronecine, a metabolite of the pyrrolizidine alkaloid monocrotaline, and were observed for 15 months for tumor development. Of 92 animals examined, 63 had tumors at the site of application or injection; 47 of these had skin tumors, mainly basal cell and squamous cell carcinomas. These data indicate that dehydroretronecine is a proximate carcinogen capable of causing a high incidence of skin tumours in mice at the site of sc injection or topical application.

Administration, Topical↗
PubMed1978

Monocyte function in human neonates.

Monocytes of healthy, full-term newborns were isolated from cord blood, and functional and biochemical activities were quantitated. The yield of monocytes per milliliter of cord blood was 60% greater than that from the peripheral blood of healthy adults. Placental monocytes were initially less well spread than cells from adults, but no other morphological differences were noted. During 4 days of in vitro cultivation, placental monocytes secreted lysozyme at a constant rate, lost peroxidase activity, and increased 5'-nucleotidase activity 15- to 25-fold. Similar findings were obtained with monocytes from adults. Placental monocytes also displayed Fc and complement receptor activity. Ingestion and intracellular multiplication of Toxoplasma gondii were identical in normal placental and adult monocytes. Furthermore, toxoplasma multiplication was significantly inhibited by cells from both sources when the monocytes were preincubated with supernatants prepared from sensitized lymphocytes and toxoplasma antigen. Monocytes from newborns were competent cells in terms of the specific functions and activities we examined.

Adult↗
PubMed1978

Fixatives and methods of fixation in selected tissues of the laboratory rat.

The histologic appearances of tissues fixed by immersion and perfusion were compared, as well as the effects of these different fixatives: 10% neutral buffered formalin, Carnoy's fluid, and Bouin's fluid. Intravascular perfusion provided better tissue preservation than fixation by immersion. The quality of preservation by neutral buffered formalin was equal to that of Carnoy's fluid and Bouin's fluid, but the overall staining quality of the latter two was judged to be superior.

Animals↗