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Biomedical subjects

R C Davis

Publications and source records attributed to R C Davis.

At least 109 records · Page 6Linked to original sources
PubMed1976

Prolongation of allograft survival by combination therapy with anti-thymocyte serum and anti-immunoglobulin.

Heterologous anti-immunoglobulin (AI) is a potent immunosuppressive agent which compares favorably to anti-thymocyte serum (ATS) in inhibiting E and EAC-rosette formation and diminishing the secondary antibody response to sheep erythrocytes and E. coli lipopolysaccharide. AI prolongs H-2 incompatible skin allograft survival than either antiserum used alone, without evidence of toxicity to recipient mice. AI does not cause significant immune complex glomerular or renovascular deposition and may act by interference with antigen binding.

Animals↗
PubMed1975

Spectral properties of Co(II)- and Ni(II)-activated rabbit muscle pyruvate kinase.

Stoichiometry, kinetics, and optical properties of rabbit muscle pyruvate kinase activated with Co(II), Ni(II), Mg(II), and Mn(II) were studied. The stoichiometry of metal binding to enzyme was found to be 4 metal ions per tetrameric enzyme for Co(II) and Ni(II) by carrying out circular dichroic titrations. Cu(II) and Fe(II) were inactive. Ca(II) and Zn(II) were not activating, and were inhibitory with respect to all of the active cations. The temperature dependence of the optimal velocity is similar for all activating metals. The pH rate profiles suggest that there are two classes of enzyme activation by metal ions. Mg(II) and Mn(II) are quite similar to each other while Co(II) and Ni(II) are different from them but similar to each other. Absorption, natural, and magnetic CD in the visible region were used to probe the environment of the activating divalent cation in Ni(II)- and Co(II)-activated pyruvate kinase and their complexes with substrates and inhibitors...

Animals↗
PubMed1975

Phosphoenolpyruvate hydrolase activity of rabbit muscle pyruvate kinase.

Rabbit muscle pyruvate kinase catalyzes the hydrolysis of P-enolpyruvate at the same active site which catalyzes the physiologically important kinase reaction. The hydrolase activity is lower than the kinase activity by a factor of at least 10(3). There are specific monovalent cation and divalent cation requirements. No other cofactors are required. The relative activation of the pyruvate kinase for the hydrolase reaction is: Ni(II) greater than Co(II) greater than Mg(II) greater than Mn(II). This parallels the rates of nonenzymatic hydrolysis of P-enolpyruvate (Benkovic, S.J., and Schray, K.J. (1968) Biochemistry 7, 4097-4102). The pH rate profiles of the hydrolase and kinase reactions activated by Ni(II) and Co(II) are similar, suggesting common features in their mechanisms. In contrast to the kinase reaction, the reaction velocity of the hydrolase increases at high Co(II) concentrations indicating a second mode for hydrolysis.

Animals↗
PubMed1975

Bypass vein grafts in patients with distal popliteal artery occlusion.

The results obtained by placing reversed autogenous saphenous vein bypass grafts in either isolated popliteal artery segments or tibial vessels distal to the popliteal artery segments or tibial vessels distal to the popliteal artery are compared. Fifty-five patients with arteriosclerotic peripheral vascular disease who were threatened with limb loss were followed up from six months to nine years prior to this report. The success rate at one year was 94 per cent for the isolated popliteal segment grafts and 73 per cent for the tibial vessel grafts. The success rate after four years was 70 per cent for the isolated popliteal segment grafts and 63 per cent for the tibial vessel grafts. The clinical factors associated with the success of isolated popliteal segment bypass grafts and the factors apparently associated with failure of vein grafts in both of these groups with very poor distal arterial outflow are discussed. Our results suggest that either an isolated popliteal artery segment graft or a tibial vessel graft is a satisfactory means of treating these patients; however, a graft to an isolated popliteal segment is probably preferable to a graft to a tibial artery.

Aged↗
PubMed1975

Successful renal transplantation in focal glomerular sclerosis: report of two cases.

The fate of renal allografts has provided much useful information about the pathogenesis of certain glomerular diseases. Idiopathic nephrotic syndrome with focal glomerular sclerosis (FGS) has been reported to recur in transplants. Two patients are reported with idiopathic nephrotic syndrome who progressed to renal failure. Immunopathologic and ultrastructural studies appeared to exclude immune pathogenic mechanisms in both patients, and light microscopic findings were characteristics of FGS. The nephrotic syndrome in one patient was initially steroid-dependent. Both patients underwent bilateral nephrectomy prior to renal transplantation. Graft function and urine protein excretion were normal in both patients 2 and 4 years respectively after transplantation, and transplant biopsies revealed no evidence of recurrent FGS. These results indicate that renal transplantation in patients with idiopathic nephrotic syndrome and FGS is not invariably followed by recurrent glomerular disease and suggest that the responsible pathogenetic mechanism(s) may not always persist.

Adult↗