Biomedical subjects
Publications and source records attributed to C D Taylor.
A growth factor present in rumen fluid and essential for growth of a rumen strain of Methanobacterium ruminantium was shown to be coenzyme M, 2-mercaptoethanesulfonic acid.
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This paper describes the first detailed study on a dihydroorotate dehydrogenase involved in pyrimidine biosynthesis. In most organisms the enzyme is membrane-bound; however, a soluble dihydroorotate dehydrogenase was produced in relatively high levels when the anaerobe, Lactobacillus bulgaricus, was released from repression. The enzyme was purified 213-fold over derepressed levels with a 39% recovery of enzyme units. The enzyme showed only one minor protein contaminant when analyzed by polyacrylamide electrophoresis. It was characterized as a flavoprotein containing only flavine mononucleotide as the prosthetic group. Molecular weight estimations by gel filtration gave a value of approximately 55,000, which is one-half that of the degradative enzyme described by others. During aerobic oxidation of dihydroorotate, the rates of oxygen consumption, orotate formation, and hydrogen peroxide formation were equal, as would be expected in a flavoprotein-catalyzed reaction. The enzymatic activity with ferricyanide as acceptor was optimum around pH 7.7. The stimulation of enzymatic activity over a wide pH range by ammonium sulfate was attributed to an effect on the maximum velocity of the reaction. As analyzed by polyacrylamide electrophoresis, inactivation of the enzyme by visible light resulted in the appearance of a second protein band with lowered specific activity. The purified enzyme used redox dyes, oxygen, or cytochrome c as electron acceptors but was not active with pyridine nucleotides. Flavine adenine dinucleotide has been implicated at the active site for pyridine nucleotide reduction in the degradative enzyme. The biosynthetic enzyme lacks this flavine and the associated activity.
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Reports exist in the literature where metastasis or inadvertent operative spread has transferred excised squamous cell carcinoma, keratoacanthoma, and melanoma to skin graft donor sites. This report examines the potential for the reverse to occur. A de novo squamous cell carcinoma developing in a split-thickness skin graft donor site within 5 weeks of harvest for acute burn coverage is presented. As repeated harvesting from this site was performed, the transplantation of carcinoma could have occurred. The etiology of this squamous cell carcinoma, the risk of transplantation, and the 18-month follow-up are presented.
Antiemetic effects of perphenazine and prochlorperazine, both administered by continuous i.v. infusion after a loading dose, were compared in patients receiving cisplatin. Study subjects were 6 men and 13 women for whom other antiemetic therapy had failed; each patient was studied during two courses of cisplatin therapy. Patients were randomly selected to receive either perphenazine or prochlorperazine during the first course; for the second course, each received the other antiemetic. During drug administration, nausea, retching, vomiting, and side effects of the antiemetic were recorded hourly by the patient and concurrently by a pharmacist observer (both blinded). Each patient's scores on nausea, retching, and vomiting were compared by drug and by treatment sequence. Evaluable data for 17 patients showed that aggregate differences between responses to the two drugs were not significant. Fourteen patients had significantly less nausea, retching, and vomiting during the second course of treatment. Few side effects were reported. Nervousness was experienced with prochlorperazine in four patients and perphenazine in one, and drowsiness occurred with prochlorperazine in four patients and perphenazine in three. Perphenazine and prochlorperazine, when given in equal doses and administered by continuous i.v. infusion after a loading dose, were equally effective in controlling nausea and vomiting associated with cisplatin therapy.