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Biomedical subjects

K Johnson

Publications and source records attributed to K Johnson.

At least 541 records · Page 30Linked to original sources
PubMed1977

In vitro stimulation of bovine circulating lymphocytes by parainfluenza type 3 virus.

Bovine circulating lymphocytes from animals sero-positive to parainfluenza-3 virus (PIV-3) could be stimulated by PIV-3 antigen in a microculture system. A semiautomatic multiple sample harvester was used to collect the lymphocytes from the microplates. Ultraviolet-killed PIV-3 induced better stimulation values than formalin or heat-treated virus. The highest stimulation values were obtained after a stimulation time of three to five days.

Animals↗
PubMed1976

A critical examination of the value of combined determinations of lecithin:cholesterol acyltransferase and lipoprotein-X in the differential diagnosis of liver disease.

The suggestion that combined determinations of lecithin: cholesterol acyltransferase activity and lipoprotein-X can be used to distinguish between patients with intrahepatic cholestasis and extrahepatic biliary obstruction has been studied. Of 21 patients who were lipoprotein-X positive and in whom an unequivocal diagnosis was made, 11 had intrahepatic cholestasis and 10 extrahepatic obstruction. The range of plasma lecithin:cholesterol acyltransferase activity was similar in the two groups and did not enable distinction to be made between them.

Acyltransferases↗
PubMed1976

Sodium polystyrene sulfonate resin candy for control of potassium in chronic dialysis patients.

A stable candy with 5.0 g sodium polystyrene sulfonate resin per piece was developed. In vitro testing indicated decrease in potassium concentration of 1.0 mEq per gram of resin. Six chronic dialysis patients with predialysis serum potassium of 5.2 mEq per liter or greater participated in a two week blind trial. No change in diet or dialysis routine was made during the study. Analysis of serum potassium by paired "t" test showed mean potassium decrease of 0.7 mEq per liter during treatment (P less than 0.001). Patient compliance and acceptance was excellent during the trial. Use in the treatment of chronic hyperkalemia may be worthwhile in the care of long-term dialysis patients.

Candy↗
PubMed1973

DD-carboxypeptidase-transpeptidase and killing site of beta-lactam antibiotics in Streptomyces strains R39, R61, and K11.

Additional evidence is given that in Streptomyces strains R39, R61, and K11 the same enzyme performs dd-carboxypeptidase and transpeptidase activities and that this enzyme is the killing site of beta-lactam antibiotics. With strain R61, it was found that the exocellular enzyme has a sensitivity towards some antibiotics different from that of the membrane-bound enzyme. Under the growth conditions used in the present investigations, beta-lactamase activity was not involved in susceptibility to beta-lactam antibiotics.

Acyltransferases↗
PubMed1973

Exocellular beta-lactamases of Streptomyces albus G and strains R39 and K11.

The beta-lactamases excreted by the highly benzylpenicillin-susceptible Streptomyces strain R39 and the highly benzylpenicillin-resistant Streptomyces albus G were isolated and purified. Neither beta-lactamase exhibited dd-carboxypeptidase activity. Both were anionic at pH 8.3, did not require metal ions, and were not sensitive to iodine, but were inhibited by Cu(2+) and readily inactivated by heat. p-Chloromercuribenzoate, iodoacetate, p-aminobenzoate, and substrates and inhibitors of dd-carboxypeptidase had no effect on beta-lactamase activity. The K(m) and V(max) values for beta-lactamase activity were studied with 6-aminopenicillanic acid and with various penicillins and cephalosporins. The beta-lactamase from the related strain K11 of Streptomyces, which is intermediate in its susceptibility to benzylpenicillin, was partially purified, and its activity was compared on the various substrates.

Carboxypeptidases↗
PubMed1973

Isolation and characterization of a bacteriophage for Thiobacillus novellus.

A DNA-containing bacteriophage for Thiobacillus novellus has been isolated from sewage and purified by ammonium sulfate precipitation, differential centrifugation, and cesium chloride equilibrium centrifugation. The buoyant density of this phage in CsCl is 1.51 g/cm(3). Electron microscopy studies have revealed a polyhedral head about 60 nm in diameter and a tail surrounded by a number of fine filaments. It has an adsorption rate constant of 1.1 x 10(-9) ml/min, a latent period of 45 min, and an average burst size of 150. The mole guanine and cytosine content in its DNA has been estimated to be 57 to 58%. Five structural proteins with molecular weights of 62,000, 42,500, 30,500, 17,750, and 13,500 have been detected by polyacrylamide gel electrophoresis techniques.

Adsorption↗