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Biomedical subjects

J M Fagan

Publications and source records attributed to J M Fagan.

41 records · Page 3Linked to original sources
PubMed1985

Relationship of the redox state to muscle protein degradation.

With increasing muscle size, incubated or fresh-frozen leg muscles showed a more reduced redox state and slower proteolysis. The ln of these data gave a linear correlation showing faster proteolysis under more oxidized conditions. In incubated diaphragms, the inhibitory effects of insulin and catecholamines on proteolysis were associated with a more reduced state. Fasting, trauma or cortisol treatment led to accelerated proteolysis and a more oxidized state. Long term fasting and refeeding supported this relationship, as did streptozotocin diabetes. Like the NAD+ and NADP+ redox couples, the glutathione couple seemed to fit this relationship. Use of proteinase inhibitors showed that the redox state probably mediated the effects of the various factors on proteolysis rather than vice versa. Muscle contains thioltransferase which catalyzes the formation of glutathione-protein mixed disulfides. We propose that increased formation of oxidized glutathione and its interaction with muscle proteins may act as a signal for the initiation of proteolysis.

Adrenalectomy↗
PubMed1984

Pathogenicity of coccidia in Japanese quail (Coturnix coturnix japonica).

Coccidia were recovered from a field outbreak in commercially raised Japanese quail from South Carolina. After propagation in unmedicated quail, the culture was identified as a mixture of approximately 65% Eimeria uzura, 33% E. tsunodai, and 2% E. taldykurganica. Several pure cultures of E. uzura were obtained by single oocyst isolation. A micropyle was not present in all oocysts; thus, it is not a reliable taxonomic characteristic for identification of E. uzura. Neither the mixed culture nor the E. uzura isolates were infective for Bobwhite quail, Chukar partridge, pheasants, chickens, or turkeys. Seventeen-day-old quail were inoculated with various doses of sporulated oocysts ranging from 5 x 10(2) to 5 x 10(5) of the mixed culture and 1 x 10(3) to 1 x 10(6) of E. uzura. The rate of weight gain was depressed at 3 or 4 days postinoculation (DPT) with as few as 5 x 10(2) oocysts/quail of the mixed culture. As few as 1 x 10(3) oocysts of E. uzura produced a weight loss. Some individual quail had depressed packed cell volume and plasma pigment compared with levels in the uninoculated controls. Plasma protein was not affected. Young quail (3 days old at inoculation) were more susceptible than 17-day-old quail. Infection did not adversely affect body weights of adult quail, although egg production was reduced. Mortality was seen only with the mixed culture (100 and 8% in 3- and 17-day-old quail given 5 x 10(5) oocysts, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1983

Response to trauma of protein, amino acid, and carbohydrate metabolism in injured and uninjured rat skeletal muscles.

Soft tissue injury to one hindlimb produced trauma in rats without affecting their food intake or weight gain. Histologic examination showed damage to the soleus and gastrocnemius muscles but not to the extensor digitorum longus muscle. The protein content of the injured soleus muscle was lower than that of the contralateral soleus at one day after injury, and was reflected in vitro by a faster rate of protein degradation. The injured soleus also showed greater rates of protein synthesis, glucose uptake, glycolysis, oxidation of glucose, pyruvate, and leucine, and de novo synthesis of alanine. During three days after the injury, urinary nitrogen excretion increased progressively and was paralleled by a faster rate of protein degradation in uninjured muscles incubated with glucose, insulin, and amino acids. In these muscles, the inhibition of protein degradation by insulin diminished, while its stimulation of protein synthesis was unaffected. This insensitivity of proteolysis to insulin in trauma can explain the increased rate of this process. The oxidation of glucose and pyruvate were lower in the diaphragms of traumatized than of normal rats incubated with leucine, while glycolysis and uptake of 2-deoxyglucose did not differ. The degradation of leucine and isoleucine was greater in the diaphragms of traumatized animals and was associated with a faster de novo synthesis of alanine. For the uninjured soleus muscles of the traumatized rats, the slower rates of oxidation of glucose, glycolysis, and uptake of 2-deoxyglucose in the presence of insulin showed an insensitivity of glucose metabolism to this hormone. In contrast, no differences were seen in these various metabolic processes between the extensor digitorum longus muscles of traumatized and normal rats. These data suggest that the response of skeletal muscles to trauma may depend on their physiologic and biochemical characteristics.

Amino Acids↗
PubMed1978

Steroid myopathy.

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Adrenal Cortex Hormones↗