Isolation and properties of L-amino acid oxidase from Ophiophagus hannah venom

This paper reports the isolation and some properties of L-amino acid oxidase from Ophiophagus hannah venom. The differences between L-amino acid oxidase from Ophiophagus hannah and that from other sources in specific activity, properties and the spectrum of isozymes are noticeable. The result of electrophoresis on polyacrylamide gel shows that this purified enzyme is homogenous. The molecular weight determined by gradient polyacrylamide gel slab (4--30%) is around 15 X 10(4) dalton. The molecular weight of the subunit determined by SDS gradient gel electrophoresis (4--30%) is around 7.3 X 10(4) dalton. Therefore, this enzyme is composed of two subunits. The absorption spectrum reveals that there are two FADs in each molecule. The optimum pH of enzymic reaction is around 8.7--9.0 when L-leucine is used as substrate. The inhibition of the products is noticeable when substrate concentration goes beyond 3mM. This enzyme is heat stable and its activity would not decrease obviously after heating at 55 degrees C for 40 min. A linear relationship between enzyme concentration and reaction rate was noticed when enzyme concentration was below 5.7 micrograms/ml.

Cardiovascular effects of therapeutic doses of tricyclic antidepressants: importance of blood level monitoring

The cardiovascular effects of therapeutic doses of tricyclic antidepressants are reviewed and their clinical significance discussed. At standard therapeutic doses these antidepressant drugs produced small changes in heart rate and several intervals of the EKG in some patients, but clinically significant effects on the EKG are usually seen only in patients with high blood levels of the drugs; these high plasma levels are often above those needed for therapeutic antidepressant effects. In contrast, the orthostatic hypotension induced by antidepressants usually occurs at dosages and blood levels within the therapeutic range, and, therefore, this side-effect may be of greater clinical significance in standard clinical treatment with antidepressants. A review of recent studies suggest that adequate doses of antidepressants may be used safely in geriatric depressed patients and in many patients with stable preexisting cardiac disease. However, more frequent monitoring of plasma levels of antidepressants and EKGs may be particularly important in these groups of patients.

Detection of viral proteins in mouse mammary tumors by immunoperoxidase staining of paraffin sections

An indirect immunoperoxidase method is described, which can readily detect viral antigens in paraffin sections of primary, transplanted, and metastatic mammary tumors of mice. In addition to having the obvious advantage of not being limited to fresh specimens, immunoperoxidase staining of paraffin sections proved to be superior in many respects when compared with immunofluorescence and frozen sections. Immunoperoxidase staining of paraffin sections is permanent and provides the kind of histological detail required for precise cytological identification and localization with light microscopy. All of 25 tumors and 4 metastatic lesions showed evidence of glycoprotein gp52 as well as other mouse mammary tumor viral antigens. The pattern and intensity of the stain were related to the degree of histologic differentiation of the tumor. Wide variations in expression of viral antigens by individual malignant cells were observed within the same tumor.