Biomedical subjects
Publications and source records attributed to K Gibson.
Osteochondral fragments, which originated from the proximolateral ridge of the talus, were discovered in an 8-month-old Rottweiler. A large fragment was reattached, using a lag screw and wire. Microscopic examination of a small fragment suggested the lesion resulted from osteochondritis dissecans. Stabilization of the major fragment resulted in acceptable joint function.
Human serum sickness is a syndrome characterized by fever, malaise, skin rashes, arthralgias, gastrointestinal disturbances, and lymphadenopathy. It is believed to be mediated by circulating immune complexes composed of a foreign antigen and host antibody. Several cephalosporins have been associated with serum sickness. We report the occurrence of serum sickness in a patient who received cefoxitin, a commonly used cephamycin antibiotic, and pentoxifylline, a xanthine derivative that improves the flow properties of blood by decreasing its viscosity. Serum sickness has not been previously reported with the use of cefoxitin or pentoxifylline.
The optimal assay conditions for rat myocardial cytosol protein kinases have been determined. The assay medium contained in 0.25 ml: 40 mM Tris/HCl pH 7.4, 5 mM MgCl2, 600 micrograms histone f1, 10--30 micrograms enzyme protein, 32 microM [gamma-32P]-ATP, with or without additions of 1 microM cAMP. The incubation time at 37 degrees C was 5 minutes. The protein kinase activity in the absence of cAMP decreased with development, while the activity in the presence of cAMP remained unchanged. The protein kinase activity of the left ventricle was higher than that in the right ventricle.
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A small, but not significant, decrease in ornithine decarboxylase activity occurred in isolated hearts during one hour of recirculating perfusion with Krebs-Henseleit solution. A significantly greater decrease occurred with a non-recirculating system. Ornithine decarboxylase activity was the same in the working heart preparation as in the non-working preparation. It is concluded that a substance, necessary for the maintenance of ornithine decarboxylase, is removed during perfusion. The nature of the mechanical activity of the heart did not appear to be a determining factor.
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Right ventricular hypertrophy induced by hypobaric conditions was accompanied by an increased collagen mass. Left ventricular collagen was unaffected. Right ventricular mass remained unchanged after involution of right ventricular hypertrophy on return to normobaric conditions. Dietary restriction limited the size and collagen mass of both ventricles.
Estimates of the collagen concentration in human ventricles have been made from measurements of the hydroxyproline concentration. In the normal heart the concentration of collagen was higher in the right ventricle than in the left ventricle. Age had no effect on the ventricular concentration of collagen. Hypertrophy in the absence of a valvar lesion was not associated with an increased concentration of collagen but, owing to the increased size of the ventricle, there was an increase in the estimated total mass of ventricular collagen. The concentration of collagen in the left ventricle of patients with aortic stenosis was higher than normal. Ventricular hypertrophy seems to be accompanied by an increase in the total mass of collagen whatever the cause. Whether the concentration changes or not depends on the proportion in which the mass of collagen increases relative to the mass of muscle cells.
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Ornithine decarboxylase activity was higher in the left ventricle than in the right ventricle of the rat. Swimming exercise for 2 hours caused an increase in left ventricular but not right ventricular enzyme activity. This effect was not influenced by the prior injection of propranolol, which also had no influence on the resting level of ornithine decarboxylase activity. After 4 hours' exposure to 400 mm Hg the decarboxylase activity became greater in the right ventricle. This was attributed to the increased work-load on the right ventricle caused by hypoxic pulmonary hypertension. In the left ventricle, ornithine decarboxylase showed an initial increase in activity followed by a transient decrease at 16 hours. Propranolol had no effect on the changes observed in either ventricle. It is concluded that beta-receptor stimulation is not involved in the mechanism of an increased myocardial ornithine decarboxylase activity during increased cardiac work.
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Rats treated with T3 (triiodothyronine) showed an increased heart weight after 3 days reaching 100% after 3 weeks of treatment compared to untreated controls. Cytosol protein kinases were not significantly different in the T3 treated rats compared to controls. The protein kinase activity of the NHP (nonhistone proteins) increased after 2 hours and doubled after 3 days for each substrate tested. After 1 week of T3 treatment the protein kinase activity returned to the control value and remained at the control level for the remainder of the 3 week experimental period. A study of the distribution of protein kinase activity in the NHP by disc gel electrophoresis showed that there was a difference in the distribution of some peaks in the T3 treated animals compared to the controls. T3 in concentrations from 10(-11) to 10(-3) M had no in vitro effect on the phosvitin kinase activity of NHP and of cytosol.
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