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Biomedical subjects

H L Johnson

Publications and source records attributed to H L Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1976

Changes in pulmonary volumes with relocation to 1,600 m following acute translocation to 4,300 m.

In studies of 12 volunteer subjects, VC and ERV significantly decreased during a 3-d sojourn at 4,300 m while VE, VT, TLC, FRC and RV were elevated. Acid-base parameters showed typical changes associated with translocation to high altitude. Thus, PaO2, PaCO2 and SaO2 were immediately reduced upon translocation to 4,300 m, while the compensatory reduction in arterial HCO3- concentration was delayed temporarily by 24 h; pH, however, remained essentially unchanged throughout the sojourn. Upon relocation to 1,600 m, there was a gradual return to VC, ERV, TLC and RV to prealtitude values. FRC, on the other hand, remained elevated as did VE and VT through the third day of relocation to 1,600 m. PaCO2 and arterial HCO3- concentration showed a slight delay in returning to prealtitude values upon relocation, while the remainder of the acid-base measurements returned to prealtitude values within 24 h. The conclusion drawn from these results indicates a physiological adjustment period as long as 3 d may be required for individuals returning from a 72-h sojourn to high altitude (4,300 m).

Acclimatization↗
PubMed1975

Contact urticaria syndrome. Contact urticaria to diethyltoluamide (immediate-type hypersensitivity).

Contact urticaria refers to a wheal-and-flare response occurring on the application of chemicals to intact skin. Standard closed patch tests read at 48 hours after application yield misleading information; observations should be made instead using open patch tests 15 to 30 minutes after application. There are three major subdivisions of the syndrome: nonimmunologic cause (such as application of histamine), immunologic cause (immediate hypersensitivity), and uncertain cause (such as application of ammonium persulfate). Our patient had contact urticaria due to the insect repellent, diethyltoluamide. The experimental data suggest that this case was due to an immunologic response (immediate hypersensitivity) and demarcates the specificity of response. The immunologically mediated cases cover a broad spectrum of manifestations from contact urticaria only to local urticaria plus asthma and, in extreme sensitivity, includes anaphylactoid responses.

Adult↗
PubMed1975

Protein metabolism during intensive physical training in the young adult.

Two groups of men consumed two levels of protein (1.4 and 2.8 g/kg body weight) during a 40-day experimental period. Physical activity and the sweat rates were fairly high during the entire experimental phase. Urinary nitrogen excretions remained fairly constant for both groups during the training and heavy physical activity periods. Nitrogen balances were positive exclusive or inclusive of the daily sweat nitrogen losses showing nitrogen retention. The essentially unchanged blood hemoglobin and serum protein levels showed that the control group was receiving an adequate protein intake to maintain nitrogen equilibrium, under conditions of fairly heavy physical acitvity. Although others may have suggested some compensatory reductions in the urinary excretion of nitrogen under conditions of profuse sweating, our data have not supported these conclusions. It appears that sweat losses of nutrients become relevant in determining requirements and will increase in importance as sweat rates are increased. The data again demonstrate that the nutrient losses during profuse sweating consitute an error that could seriously invalidate the accuracy of metabolic balance studies. In this study, although the men did increase body protein stores and muscle mass with high-protein diets, the additional body protein did not enhance physiological work performance. It is suggested that in this sutdy 100 g of protein/day was adequate for men performing fairly heavy work.

Adult↗
PubMed1975

Organ fluid changes and electrolyte excretion of rats exposed to high altitude.

Electrolyte balances, serum electrolyte concentrations, and fluid changes in the liver, spleen, kidney, heart, and brain of albino rats were studied at Denver (1620 m) and Pike's Peak (4300m), in Colorado. Control animals were subjected to pair feeding and equal transportation stress. Animals were sacrificed after 2, 4, 6, 8, 10, and 12 h, and 1, 2, 3, 6, 9, and 12 d of exposure. There was no significant growth depression after the first 24 h at altitude. The water content of all tissues were increased during the first day of exposure. Liver showed an increased percent dry weight following 1 d, possibly due to an increase in fat content. Serum Na plus concentrations were significantly increased throughout the 12 d of exposure while K plus was decreased. Hematocrit and hemoglobin values were immediately increased at altitude with the RBC count being significantly higher by Day 9. Altitude rats retained more Na plus, K plus, Ca plus plus, and Mg plus plus than controls, with K plus and Ca plus plus showing the highest retention. The data indicated a shift of fluids from the extra- to the intracellular compartment, especially during the first 12 h of exposure.

Altitude↗