Purification of a nuclease from human serum

Summary The purification procedure for a nuclease from human serum is described. It includes ammonium sulfate precipitation, chromatography on DEAE-Sephadex and on Sephacryl-S 200, and preparative electrophoresis. The enzyme, purified about 2000-fold, is homogeneous in a sodium dodecyl sulfate electrophoretic system, where it has a mol. wt of 78,000. The pH optimum lies around pH 6.5; it is a sugar-nonspecific endonuclease.Acknowledgment. This work has been supported by a research grant from Stiftung Volkswagenwerk through the Akademie der Wissenschaften und der Literatur, Mainz. We thank Mrs R. Nehrbass and Mrs C. Wolpert for technical assistance.     

Acute stress reduces the sensitivity of the vasculature to sympathetic control

Vascular smooth muscle from rabbits subjected to acute severe stress exhibits decreased sensitivity to sympathetic regulation. Stimulation of the sympathetic innervation of isolated vascular segments resulted in a similar subsensitivity as did exposure to norepinephrine (NE) but not histamine. Periodic contraction of these segments caused an increase in their maximum ability to contract independent of the constrictor procedure used. These results suggest that the increase in sympathetically mediated NE release that occurs in stress and some other pathological conditions may result in a blunting of neural control and possibly resistance to certain therapeutic agents.     

The effect of various diuretic agents on renal electrolyte and urea concentration gradients in rats

Zusammenfassung Die Konzentrationsgradienten von Na+und Harnstoff im Rattennierengewebe werden durch intravenöse Applikation von Merallurid, Salyrgan und Hydrochlorothiazid nicht beeinflusst. Die Änderung des Na-Gradienten nach Aminophyllin hängt von der Injektionszeit ab. Acetazolamid-, Chlorothiazid- und Furosemid-Injektion führt jedoch zur Senkung oder zum Verschwinden eines Na-Gradienten. Die Kaliumkonzentration in der Rinde und Papilla wird durch Hg- und Sulfonamid-Diuretica erniedrigt.     

Whole-bodyγ-irradiation,food intake and glucuronic acid excretion in rats

Zusammenfassung Ganzkörperbestrahlung bei Ratten führt zur Verminderung der Futteraufnahme und zur Reduktion der ausgeschiedenen Glukoronide. Die Ausscheidung der Glukoronide erhöht sich nach dreitägigem Hunger.

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The Puerto Rico Nuclear Center is operated by the University of Puerto Rico under Contract No. AT-(40-1)-1833 for U.S. Atomic Energy Commission.