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Biomedical subjects

W D Johnson

Publications and source records attributed to W D Johnson.

At least 289 records · Page 16Linked to original sources
PubMed1968

In vitro antimicrobial activity and human pharmacology of cephaloglycin.

Serum and urine concentrations of cephaloglycin (an orally absorbed derivative of cephalosporin C) were determined in normal volunteers and in patients. The in vitro activity of cephaloglycin was also studied. All strains of group A streptococci (Streptococcus pyogenes) and Diplococcus pneumoniae were inhibited by 0.4 mug of cephaloglycin per ml. Eighty per cent of the Staphylococcus aureus strains and about 50% of the Escherichia coli and Proteus mirabilis strains were inhibited by 1.6 mug of cephaloglycin per ml. Klebsiella-Aerobacter species were more resistant to cephaloglycin and 12.5 mug per ml was required to inhibit 70% of these strains. When single doses of 250, 500, or 1,000 mg of cephaloglycin were administered to fasting volunteers, a peak serum concentration of at least 0.5 mug per ml was achieved. A full breakfast did not interfere with absorption of cephaloglycin. Probenecid enhanced both the peak serum concentration and the duration of antibiotic activity in the serum. Serum concentrations of cephaloglycin were even higher in patients who were receiving repeated doses. The peak serum concentrations of cephaloglycin in all volunteers and patients were adequate to inhibit all strains of group A streptococci and D. pneumoniae. Many of the peak serum concentrations were adequate to inhibit some strains of S. aureus, E. coli, and P. mirabilis. Urine levels of cephaloglycin were high enough in all volunteers and patients to inhibit more than 90% of the E. coli and P. mirabilis strains and over 70% of the strains of Klebsiella-Aerobacter.

Bacteria↗
PubMedDate not supplied

Long-term follow-up of patients with Leishmania (Viannia) braziliensis infection and treated with Glucantime.

Seventy-nine patients with cutaneous (62) or mucosal (17) infection with Leishmania (Viannia) braziliensis in Três Braços, Bahia, Brazil, were followed for at least 4 years after initiating treatment with antimony. Cutaneous relapses occurred in 6/62 (10%), mucosal relapse after cutaneous infection in 2/62 (3%), and mucosal relapse after mucosal disease in 2/17 (17%). It is concluded that relapse (cutaneous and mucosal) is rare after adequate antimony therapy and that no definite prediction of relapse (clinical, serological or by skin reaction) is possible.

Adolescent↗
PubMedDate not supplied

Visceral leishmaniasis in a new ecological niche near a major metropolitan area of Brazil.

In 1991, a community cross-sectional study was conducted in a village situated near the beach and close to Salvador, the capital city of Bahia, in Brazil, to determine the prevalence of visceral leishmaniasis since 1989. A serological survey was made of human and canine reservoirs and an intradermal skin test for leishmaniasis was used to assess cellular immune responses. Nearly 30% of the 243 individuals in the study area had positive skin tests and 14% had positive serology, the latter being compatible with recent infection; 29 of 460 dogs examined were seropositive. A possible association was observed between human infection and the presence of dogs in or near residences, but not between human infection and malnutrition. This report describes the evolution of a new focus of visceral leishmaniasis, its expansion toward a metropolitan area, and current measures taken to control the epidemic.

Adolescent↗
PubMedDate not supplied

Response of adult murine uterine epithelium to 50% methoxychlor.

This study was designed to assess the response of uterine epithelia of adult mice to a 4-week exposure of 50% methoxychlor (MXC) to ascertain whether significant changes were induced by 50% MXC that might compromise future implantation. Sexually mature virgin female mice were exposed to 0.1, 0.5, 1.0, 2.5, or 5.0 mg MXC via oral gavage for 5 consecutive days for 4 weeks. Controls received either sesame oil or 25 micrograms estradiol-17 beta (E-17 beta) also by gavage. At sacrifice, segments from each uterine horn were prepared for morphometric studies or for transmission electron microscopy. Results revealed a dose-dependent increase in the heights of uterine epithelial cells. Epithelial cell heights of the two groups treated with the highest doses of the pesticide were similar to that of the E-17 beta-treated group. Electron microscopy revealed increased vacuolization and swelling of mitochondria in cells of the 2.5 and 5.0 mg treated groups when compared to either of the control groups. In addition, there were effects on the number and size of microvilli in the uterine epithelial cells. The present study clearly demonstrates that a 4-week exposure of adult female mice to 50% MXC elicits significant estrogenic and toxic effects on the uterine epithelium.

Animals↗
PubMedDate not supplied

Absence of Chlamydia pneumoniae in surgical specimens of coronary and carotid arteries by polymerase chain reaction.

PURPOSE: Several recent articles indicate the renewed interest that Chlamydia pneumoniae is associated with and contributes to arterial diseases. Associations have been established for coronary arteries, carotid arteries and abdominal aortic aneurysms by serological studies, immunofluorescence and DNA-specific testing. The purpose of this study was to determine the presence of C. pneumoniae in coronary artery plaques, carotid artery plaques and old vein grafts that were harvested at the time of surgery. METHODS AND MATERIALS: Interventions were carried out on patients with carotid artery disease and coronary disease based upon their anatomic findings and symptomatology. Plaques were removed from the carotid arteries with standard endarterectomy techniques. The coronary plaques were removed utilizing blunt dissection to peel the plaque from the coronary artery. Old vein grafts were harvested during repeat surgery by excising the vein grafts. The tissue specimens were analyzed by polymerase chain reaction (PCR). RESULTS: Ninety-nine specimens from 68 consecutive patients with advanced coronary atherosclerosis with or without cerebrovascular disease were analyzed. We failed to find C. pneumoniae in any of the vascular tissue. CONCLUSIONS: A large cooperative study involving surgical specimen analysis is needed to assess the role of C. pneumoniae in the etiology of atherosclerosis.

Blood Vessel Prosthesis↗
PubMedDate not supplied

Relationship between respiratory cancer and wetlands residency in Louisiana.

Cancer mortality is high among white men residing in southern Louisiana parishes (counties). In an effort to elucidate this phenomenon, we studied three environmental correlates of cancer-namely, smoking, residence in urban communities, and residence in the wetlands. Multiple regression analysis was applied to cancer mortalities adjusted for age and urban residency, and specific for race, sex, amount of standing water area in the parish, and cancer site. Cancer sites were grouped according to their correlation with smoking: strong, moderate, and no correlation. For men, the smoking-related cancer mortality not only showed an association with residence in wetlands but also was higher in the Louisiana wetlands than in the remainder of the United States.

Bronchial Neoplasms↗
PubMedDate not supplied

Additive statistical effects of cadmium and lead on heart-related disease in a North Carolina autopsy series.

The association of heart-related mortality with tissue cadmium and lead in a study of autopsies performed on persons who resided in a soft-water, leached-soil area of North Carolina was examined. Liver cadmium concentrations and aortic lead level were indices of these elements. Both cadmium and lead levels had statistically significant correlations with cause of death (heart-related disease vs. non-heart-related disease, excluding cancer). Although cause of death was significantly associated with age, the association with cadmium and lead persisted after statistical adjustment for the effect of age. The combined effects of cadmium and lead provided sufficient information in an additive model to predict cause of death correctly for 80% of the cases, with age contributing insignificantly. These findings indicate the intimate relation of these two trace metals with increased risk of heart-related mortality, even in light of known conventional causes of such deaths.

Adult↗
PubMedDate not supplied

Symmetry in square contingency tables: tests of hypotheses and confidence interval construction.

Bowker's test, a generalization of McNemar's test, performs well under the hypothesis of symmetry, but the estimator of variance used in the test is biased when the table is asymmetric and this calls into question the test's performance in non-null situations. We seek an alternative to Bowker's test in search of methods for simultaneous inference that are valid when the hypothesis of symmetry is false. We apply multivariate normal theory to develop chi-square tests and simultaneous confidence intervals for inferences concerning symmetry in k X k contingency tables. We propose a modified Wald statistic as a competitor to Bowker's test. We also proffer quadratic estimators of confidence intervals. In large samples, the recommended test statistic rejects the null hypothesis at the stated level of significance when the null hypothesis is true and always rejects with greater power than Bowker's test. The proffered interval estimators provide good simultaneous coverage of the pairwise differences between the population proportions at the stated confidence level.

Biometry↗