Biomedical subjects

D Kahn

Publications and source records attributed to D Kahn.

At least 307 records · Page 17Linked to original sources

PubMed1978

[Toxicity of propyphenazone].

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Animals↗

PubMed1977

Affinity chromatography on agarose-hexyl-adenosine-5'-phosphate of methionyl-tRNA synthetase from Escherichia coli. Application of the couplings between the methionine and ATP sites.

Recent studies by us [Biochemistry (1977) 16, 2570-2579] have shown that L-methioninol, a methionine analog lacking the carboxylate negative charge, enhances the affinity of AMP for methionyl-tRNA synthetase while L-methionine antagonizes the nucleotide binding. Such couplings between ligands of the enzyme have now been applied to affinity chromatography of methionyl-tRNA synthetase on an agarose-hexyl-adenosine-5'-phosphate gel (the spacer is attached to AMP at the adenine C-8 position). Retention of the enzyme on this gel column was shown to be dependent on the presence of appropriate concentrations of magnesium and of L-methioninol in the equilibration buffer. The enzyme was then specifically recovered from the column by omitting the amino alcohol or by adding an excess of L-methionine which antagonizes the cooperative effect of L-methioninol. This approach has provided the basis for a new purification procedure of methionyl-tRNA synthetase which leads to a 200-fold purification in a single chromatographic step. In this manner, after 30-50% ammonium sulfate fractionation of extracts of Escherichia coli EM 20031 (carrying the F32 episome), 0.25 mg X methionyl-tRNA synthetase was obtained at 90% purity per ml of agarose-hexyl-adenosine-5'-phosphate gel.

Adenosine Monophosphate↗

PubMed1977

Comparative study of healing and remodeling in various bones.

The effects of normal physiologic stimuli on healing and remodeling in various bones of different embryogenic origin in the rabbit and dog were compared. The findings disclosed that the healing and remodeling of the tibia and mandible were consistent with the magnitude of the forces that act on these bones; namely, the tension created by muscle contraction and the compression exerted by body weight in the tibia, and masticatory compression in the mandible. The slower healing and remodeling in the maxilla was attributed to the selection of the excision of bone in the edentulous site with minimal masticatory compression and muscle-pull tension. The excision of the bone in the skull appeared to heal by fibrous tissue with no evidence of remodeling, which is consistent with the minimal external forces that act on this bone.

Animals↗

PubMed1975

Myocardial metabolic studies in prolapsing mitral leaflet syndrome.

Patients with prolapsing mitral leaflet syndrome (PML) frequently have chest pain of undetermined etiology. Twenty-three patients with PML underwent cardiac hemodynamic, angiographic, and metabolic studies. The latter were performed during control spontaneous heart rate and tachycardia by right atrial pacing. Myocardial supply-demand ratio (DPTI:SPTI) was estimated from the planimetric integration of the diastolic area (diastolic pressure time index = DPTI) and systolic area (systolic pressure time index = SPTI) of the central aortic pressure. Chest pain during pacing occurred in five patients. In two patients, it was associated with ST depression typical of ischemia on the electrocardiogram. Myocardial lactate abnormalities (lactate production or less than 10% extraction) occurred in seven patients during pacing tachycardia and was present in two patients during control state. DPTI:SPTI ratio during control state was 1.22 (+/- 0.07 SE) and decreased to 0.85 (+/- 0.05 SE) during pacing tachycardia. It is concluded that the myocardial lactate abnormalities in PML, which were present in approximately 30% of the patients in the present series, are most likely due to myocardial hypoxia. Whether or not the hypoxia is secondary to "small vessel disease" is not elucidated by this study.

Adult↗

PubMed1975

Aortocoronary vein graft surgery in a cadaver kidney transplant recipient.

A case of Prinzmetal angina occurred in a recipient of a cadaver kidney transplant who was treated with aortocoronary vein graft. The patient had severe retrosternal chest pain associated with ST-segment elevation in the precordial leads. Coronary arteriograms disclosed two major lesions in the proximal anterior descending artery. Aortocoronary vein graft was successfully performed with no untoward effect on the renal status. The patient has been free of angina approximately two years postoperatively.

Adult↗

PubMed1975