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Biomedical subjects

B Johnson

Publications and source records attributed to B Johnson.

At least 361 records · Page 20Linked to original sources
PubMed1978

Seeking truth in heroin indicators: the case of New York City.

An epidemiological investigation of New York City's indirect indicators of heroin activity from 1970 through 1976 yielded insights about New York City heroin trends. Indirect indicators were gathered from official data sources, such as law enforcement, health, and treatment agencies. Since each indicator had significant limitations inhibiting interpretation, a factor analysis of the indicators was performed, resulting in the reduction of a large number of variables to a small number of factors. The factor analysis demonstrated the way in which New York City indicators cluster or move together--a "street" component, including arrests, hepatitis, price and purity of retail heroin; a "new admissions to methadone treatment" component; and a "readmissions to methadone treatment" component. Furthermore, the analysis revealed the time-lag relationships between components--"new admissions to methadone treatment" lag 1--2 years behind the "street" component; "readmissions to methadone treatment" lag 1--3 years behind the "new admissions" component. Finally, the 1970--1976 factor scores were related to 1970--1974 estimates of narcotic addicts in New York City in regression analysis, and were also projected through 1978, yielding estimates of New York City's heroin addict population from 1975 through 1978.

Crime↗
PubMed1978

Factors influencing the susceptibility of Candida albicans to the polyenoic antibiotics nystatin and amphotericin B.

Factors influencing the interaction between Candida albicans and the polyenoic antibiotics nystatin and amphotericin B have been investigated using a K+-specific electrode to measure polyene-mediated efflux of cellular K+. In batch cultures, sensitivity was a function of culture age. Using continuous (chemostat) cultures, the influence of growth-limiting substrate, specific growth rate, growth temperature and growth pH were examined. Carbon-limited cultures showed the highest sensitivity of those substrates tested, and susceptibility increased with growth rate. Within the range 22 to 42 degrees C, growth at lower temperatures resulted in increased sensitivity, whilst a similar trend was observed when the growth pH of cultures was reduced. Further, under the conditions tested, there were considerable variations in free intracellular K+ concentrations.

Amphotericin B↗
PubMed1977

Mortality among women participating in the Oxford/Family Planning Association contraceptive study.

43 deaths are known to have occurred among the 17 032 participants in the Oxford/Family Planning Association contraceptive study up to the end of April, 1977. 9 deaths from cardiovascular causes have been observed among the women in the oral-contraceptive entry group (49 681 woman-years of observation) while no such deaths have been observed among the women who entered the study while using a diaphragm or an intrauterine device (39 146 woman-years of observation). These findings are consistent with the results presented in the accompanying report from the Royal College of General Practitioners Oral Contraception Study.

Adult↗
PubMed1977

The care of oral contraceptive users by general practitioners in Oxfordshire.

A questionnaire was circulated to a sample of general practitioners in Oxfordshire enquiring about the supervision of women taking oral contraceptives. A high standard of care was being offered and the doctors believed that there was a wide range of conditions that should influence the prescription of oral contraceptives. We conclude that while suitably trained paramedical staff could provide the same standard of care as the general practitioners, this could not be achieved through the use of a package insert listing possible contraindications.

Contraceptives, Oral↗
PubMed1976

Jamaican vomiting sickness. Biochemical investigation of two cases.

We identified methylenecyclopropylacetic acid, a known metabolite of hypoglycin A, in the urine of two patients with Jamaican vomiting sickness. Excretion of unusual dicarboxylic acids such as 2-ethylmalonic, 2-methylsuccinic, glutaric, adipic and dicarboxylic acids with eight and 10 carbon chains were also detected in both patients. The amounts of these dicarboxylic acids were 70 to 1000 times higher than normal. These metabolites have also been identified in urine of hypoglycin-treated rats. This evidence links hypoglycin A to Jamaican vomiting sickness as its causative agent. Urinary excretion of short-chain fatty acids was also increased up to 300 times higher than normal. These results indicate that, despite their clinical and histologic similarities, the cause and biochemical mechanisms of Jamaican vomiting sickness differ distinctly from those of Reye's syndrome in which these abnormal urinary metabolites are not appreciably increased.

Animals↗
PubMed1976

Identification of ethylmalonic acid in urine of two patients with the vomitting sickness of Jamaica.

Large amounts of ethylmalonic acid have been identified in urines from two patients with the vomitting sickness of Jamaica. The amounts were 178 and 882 mug per mg creatinine which are 70 and 350 times, respectively, over control values. Other short and medium chain dicarboxylic acids including glutaric and adipic acids and those with eight and ten carbon chain, saturated and cis-unsaturated, were also detected in large quantities as in the case of hypoglycin treated rats; urine. However, the large increase of urinary ethylmalonic acid in these two human cases is in a sharp contrast to the findings in hypoglycin treated rats in which urinary ethylmalonic acid increased only 3 times over control. It appears that ethylmalonic acid is produced in the cases with the vomiting sickness of Jamaica by carboxylation of n-butyryl-CoA which is not oxidized further due to the inhibition by hypoglycin A. In case of hypoglycin-treated rats, n-butyryl-CoA is mainly conjugated with glycine or deacylated to free butyric acid.

Animals↗