The earliest known event in the sequence leading to mitosis is the duplication of cell centers. The present investigation shows that the synthesis of DNA, although closely following it in time, is initiated entirely independently of this prior event. Fertilized eggs of the sea urchin, S. purpuratus, were exposed to beta-mercaptoethanol at intervals during development. This substance, when intro...

Colony-forming capacity of human melanoma cells was investigated in five established cell lines and isolated cells from seven metastatic or recurrent tumors. A single-cell suspension was added to 0.3% agar medium, and colonies were observed over 7 to 21 days. With the five cell lines, colony formation occurred in all cases and was usually accelerated by 2-mercaptoethanol, but there was wide var...

When chicken liver dihydrofolate reductase reacts with an excess of sodium tetrathionate, 1 mol of thiosulfate becomes covalently attached to the single sulfhydryl group of the enzyme. The identity of the thiosulfate was established by obtaining 1:l binding independently with both innerand outer-labeled [36S]tetrathionate. The thiosulfate form of the enzyme has 5to 10-fold more activity than n...

Human Factor VIII/von Willebrand factor, purified by calcium citrate-cellulose chromatography and 4% agarose gel filtration was subjected to sodium dodecyl sulfate gel electrophoresis on gels containing 2% acrylamide and 0.5% agarose. We find a series of multimers of which the apparent molecular weight of the higher members was congruent with5 million. The higher multimers were isolated by 2% a...

The aim of the present study was to investigate the involvement of nitric oxide and prostaglandin pathways in the cardioprotective actions mediated by bradykinin via the combined inhibition of angiotensin converting enzyme and aminopeptidase P in an in vivo rat model of acute ischemia (30 min) and reperfusion (4 h). Myocardial infarction was produced by occlusion of the left anterior descending...

Hepatitis B e antigen (HBeAg) occurs in the serum of individuals infected with hepatitis B virus both free and in association with IgG. Utilizing a succession of steps involving salt precipitation, affinity chromatography, ion-exchange chromatography and isoelectrofocusing, we isolated free and IgG-bound forms of HBeAg from the sera of infected individuals with an overall gain in specific activ...

polyphenol oxidase (ec. 1.10.3.1 ppo), an ionically unbound and thermostable enzyme, was extracted from the leaves of cinnamomum tamala having aroma flavor used to add in indian food and vegetables as a part of spices to enhance the taste of recipes. the enzyme was purified 2.63-fold with a total yield of 9.5% by ammonium sulfate precipitation followed by sephadex g-100 gel filtration chromatog...

results the results showed that bbb test showed an improvement in the cr, while the quantitative analysis showed that the improvement rate was higher in the rats treated with cnl than those treated with bmscs only or the untreated animals, similar results were noticed in the improvement index. immunohistochemical analysis of the tissue section prepared from the cr showed that the transplanted c...