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Biomedical subjects

R A Nelson

Publications and source records attributed to R A Nelson.

At least 145 records · Page 8Linked to original sources
PubMed1975

Nitrogen metabolism in bears: urea metabolism in summer starvation and in winter sleep and role of urinary bladder in water and nitrogen conservation.

Three bears were studied under conditions of (1) no food but access to water for 2 weeks and (2) no food or water for 3 weeks. During starvation in summer, the bears could not inhibit the net production of urea but used lean body mass; when denied access to water as well, the bears became dehydrated and azotemic. Urea was continuously formed and degraded in the winter. Arginase activity in liver increased in winter sleep; hepatic steatosis and inflammatory reactions were also noted. The urinary bladder readsorbed labeled urea and D20 in winter; the rate of absorption of urea was equal to the rate of excretion of it into the bladder. The ability to preserve lean body mass during winter sleep apparently is a special mechanism associated with the induction of winter sleep. Bears cannot duplicate this feat during summertime starvation. In winter sleep, urea is formed and degraded but the nitrogen produced is conserved in some manner that maintains the total nitrogen pool constant. The urinary bladder plays a central role in maintaining the state of winter sleep by absorbing water and solute at a rate equal to their entry into the urinary bladder.

Animals↗
PubMed1975

The effect of antibody and complement on perfused hearts: a model for the study of xenograft rejection phenomenon.

An in vitro heart perfusion system was developed to study the effect of antibody and complement on hearts in vitro, as a model to quantitatively evaluate factors involved in xenograft rejection. Both guinea pig and rabbit hearts were tested with various reagents. Perfusion of hearts with normal autologous or "homologous" sera did not induce rejection, while "heterologous" sera, normal or immune, arrested cardiac function. Either the inactivation of certain complement components or the absence of antibodies against heart tissue prevented rejection as determined by lack of change in electrocardiogram and alterations in ultrastructure. Antibody alone had no effect. A lethal effect of C6-deficient rabbit serum on guinea pig hearts was prevented by 2 antihistamines, Chlortripolon and Benadryl.

Animals↗
PubMed1975

Uremic neuropathy. III. Controlled study of restricted protein and fluid diet and infrequent hemodialysis versus conventional hemodialysis treatment.

The effect of a treatment schedule of restricted protein and fluid intake and of infrequent hemodialysis (schedule 1) as compared to a conventional hemodialysis treatment schedule (schedule 2) on the presence and severity of peripheral neuropathy has been studied in a small group of patients using a crossover design. Using the neurologic evaluation and quantitative assessment of cutaneous sensation and of nerve conduction as indices of peripheral nerve function, we have not demonstrated any worsening of peripheral nerve function from markedly curtailing the frequency of hemodialysis and modifying the diet. Because of the small size of the study, the preponderance of patients receiving the test treatment schedule first, and the possibility that nerve function slowly worsens with time, it is not possible to say with certainty that the test or the control treatment schedule might adversely affect peripheral nerve function. If such an effect is present it would appear to be small.

Adult↗
PubMed1973

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