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Biomedical subjects

B D Johnson

Publications and source records attributed to B D Johnson.

At least 145 records · Page 8Linked to original sources
PubMed1988

Effect of Army basic training in sickle-cell trait.

In order to determine if sickle-cell trait (SCT) represents an inherent adverse effect on response to training, we objectively evaluated exercise performance in 22 healthy, black men with SCT (hemoglobin AS) and 15 controls (hemoglobin AA) before and after seven weeks of army basic training at an altitude of 1270 m. An incremental exercise test to exhaustion on a cycle ergometer was used. Before basic training, peak exercise measurements did not reveal significant differences between groups other than a slightly lower, albeit significant, value for oxygen uptake (VO2) per kilogram (42 +/- 1 vs 45 +/- 1.4 mL/min per kilogram) for the SCT group. Both groups experienced modest overall cardiovascular improvement reflected in both peak and submaximal exercise responses. No statistically significant difference was observed between the SCT and the control groups at the end of basic training for any of the measured variables at peak exercise, including power (258 +/- 6 vs 266 +/- 9W), VO2 (3.24 +/- .06 vs 3.36 +/- .16 L/min), VO2 per kilogram (46 +/- 0.7 vs 46 +/- 1.2), minute ventilation (138 +/- 4 vs 147 +/- 8 L/min), heart rate (185 +/- 2 vs 184 +/- 3 beats per minute), oxygen pulse (17.6 +/- .3 vs 18.4 +/- 1 mL/min per beat), as well as anaerobic threshold (1.81 +/- .04 vs 1.80 +/- .06 L/min), respectively. No medical problems directly attributed to SCT were reported; it remains uncertain, however, whether a seizure experienced by one of the other SCT basic trainees after a two-mile run was SCT related. The results of this study would, therefore, suggest that for the majority of individuals who possess SCT, the response to the moderate training regimen provided by army basic training is not impaired.

Adult↗
PubMed1986

Acute necrotizing ulcerative gingivitis. A review of diagnosis, etiology and treatment.

Vincent's original description of the fusiform-spirochete nature of acute necrotizing ulcerative gingivitis (ANUG) still remains true today, although much additional insight has been gained regarding the etiology, pathogenesis and treatment of the disease. In addition to the historic association of fusiform and spirochete microbes with ANUG, recent findings have also implicated Bacteroides and Selenomonas species. Possible abnormalities in immunological function, such as altered PMN and lymphocyte responsiveness, may be present. Stress, which has long been known to be associated with the disease, appears to play a role through induction of increased cortisol and catecholamine levels. These chemical mediators respectively may compromise the host immune responses and the gingival microcirculation. Cortisol may also serve as a nutrient source for Bacteroides bacteria. Other predisposing factors to ANUG may include smoking and poor oral hygiene. Treatment modalities involve eliminating or reducing the levels of bacterial pathogens by mechanical and antibiotic means, along with attempts at controlling significant psychological and physical precipitating factors.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Effects of donor age on protein and collagen synthesis in vitro by human diploid fibroblasts.

Diploid fibroblast strains were established from explants of normal gingiva from donors ranging in age from 12 to 68 years. By using labeled amino acid precursors, we measured protein and collagen production, and intra- and extracellular protein degradation. Qualitative assessment of the patterns of protein production was performed by two-dimensional gel electrophoresis and detection of labeled components by fluorography. Protein and collagen production decreased more than 5-fold as a function of increasing donor age over the age range studied while protein degradation remained unaffected by donor age. The pattern of proteins produced was unaffected by donor age. These data demonstrate a large statistically significant slowdown in general protein synthesis with increasing donor age. This slowdown is not selective, but appears to affect all of the proteins being produced.

Adult↗
PubMed1985

Imidazo[1,5-d][1,2,4]triazines as potential antiasthma agents.

By using inhibition of histamine release from antigen-challenged, sensitized human basophils as a means of identifying a potentially prophylactic drug for the treatment of asthma, a series of substituted imidazo[1,5-d][1,2,4]triazines were found, which were active. These compounds were prepared by treating imidazolecarboxaldehydes with excess Grignard agent and then oxidizing the resulting alcohols to ketones with Jones reagent. Pyrolysis of a mixture of ketone and methyl carbazate at 200 degrees C in diphenyl ether produced the desired imidazo[1,5-d][1,2,4]triazines. Those compounds with the greatest basophil activity were tested for in vivo activity in the mouse passive cutaneous anaphylaxis (PCA) and the guinea pig passive anaphylaxis tests. The best compounds, 1-ethyl-8-methyl-6-propylimidazo[1,5-d][1,2,4]triazin-4(3H)- one (4-17) and 1,8-dimethyl-6-propylimidazo[1,5-d][1,2,4]triazin-4-(3H)-one (4-16) were chosen for further study.

Anaphylaxis↗
PubMed1979

Availability of oral carbohydrates to neonatal calves.

Four experiments were conducted to determine the availability of 3 carbohydrate sources given orally to 1- to 3-week-old clinically normal calves. In terms of effect on plasma glucose concentration, commercial fruit pectin was equivalent to glucose, corn syrup was less effective (P less than 0.05) than glucose, and sucrose was totally unavailable. The addition of 80 mM NaCl to a 10% glucose solution enhanced glucose absorption (P less than 0.01). Increasing the glucose concentration of a commercial product from 1% to 3% resulted in a significant (P less than 0.01) increase in plasma glucose concentration. Lactose availability from suckled fluids was greater (P less than 0.01) than that from fluids given by stomach tube.

Administration, Oral↗
PubMed1979

Potential antiarthritic agents. 2. Benzoylacetonitriles and beta-aminocinnamonitriles.

Benzoylacetonitrile and beta-aminocinnamonitrile are shown to possess potent antiinflammatory activity in the rat adjuvant arthritis model. In a series of phenyl-substituted analogues, only o-, m-, and p-fluorobenzoylacetonitrile and m- and p-fluoro-beta-aminocinnamonitrile retained activity. Additionally, beta-amino-2- and beta-amino-3-thiopheneacrylonitrile and beta-oxo-2- and beta-oxo-3-thiophenepropionitrile exhibited similar activity. These agents are not believed to be acting via prostaglandin synthetase inhibition. The metabolic profile of benzoylacetonitrile is also described.

Acetonitriles↗
PubMed1978

NAD nucleosidase of Agkistrodon bilineatus venom.

NAD nucleosidase (NAD glycohydrolase, EC 3.2.2.5) activity in Agkistrodon bilineatus venom was observed. Using the cyanide assay method at pH 7.9, lyophilized crude venom had an activity of 0.19 units/mg. Chromatography of the crude venom on DEAE Sephadex A-50 with ammonium acetate buffer by two stage elution yielded 13 fractions. Peak NAD nucleosidase activity occurred at Fraction X. Crude venom and Fraction X NAD nucleosidase activities were thermolabile.

Animals↗
PubMed1978

A comparative study of five groups of handicapped children in vocational rehabilitation.

This study explored the vocational and educational plans, work values, realism, initiative commitment to choice, and awareness of occupational information of five groups of handicapped children compared with a group of normal children in grades 6--12. Handicapped children tested significantly lower on all measures of vocational development. Only the cystic fibrosis group approached the high scores of the normal group. Age, grade, and social class were the best predictors of vocational development in all six groups. The findings confirmed the hypothesis that handicapped children are less prepared for vocational training and placement and consequently require special rehabilitation programs to prepare them for work.

Adolescent↗
PubMed1977

How much heroin maintenance (containment) in Britain?

The British policy of providing heroin legally to a few addicts at Drug Treatment Centres (DTCs) is referred to as "heroin maintenance" in America and as "containment" of heroin in Britain. Virtually unknown statistics produced by the Home Office for the United Nations are reproduced in some detail to make them widely available to professional researchers. These statistics indicate that the provision of legal heroin is very rare: about 4% of British opiate addicts at DTCs receive heroin without methadone for over one year. About 12% receive heroin and/or methadone for a year or more. The majority of British addicts are maintained on methadone only. Shifts in drugs being prescribed are due more to patient turnover than to physicians switching addicts from heroin to methadone. Implications of this data for the transatlantic debate on heroin maintenance are considered. An appendix of references on British opium policy is included.

Adult↗