Relationship between duodenal pH and pancreatic secretion in dogs and pigs

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Isolation and amino acid composition of human angiotensin I

1. Angiotensin, the most powerful pressor substance known, suspected to be a causal substance in renal hypertension and previously isolated from animal sources, has now been isolated from human sources and the amino acid composition was analysed. 2. The procedures followed in the successful isolation of human angiotensin include: (a) preparation of stable materials to obtain maximum formation of human angiotensin; (b) a relatively selective adsorption of the formed angiotensin on Dowex 50W (X2); (c) gel filtration through Sephadex G-25; (d) cation-exchange chromatography on CM-cellulose; (e) anion-exchange gel filtration on DEAE-Sephadex A-25; (f) molecular-sieve chromatography through Bio-Gel P-2. 3. The homogeneity of the human angiotensin isolated was confirmed by paper and thin-layer chromatography and paper electrophoresis. 4. The biological activity observed indicates the substance isolated to be human angiotensin I. 5. The amino acid analysis suggested the following proportional composition: Asp, 1; Pro, 1; Val, 1; Ile, 1; Leu, 1; Tyr, 1; Phe, 1; His, 2; Arg, 1. This composition is similar to that of horse angiotensin I, i.e. isoleucine(5)-angiotensin I.

Heat resistance of spores of Clostridium welchii

Eight strains ofCl. welchiiwere studied for the heat-resistance of their spores. Spores ofCl. welchiiisolated from food-poisoning cases had greater heat-resistance than strains isolated from soil or faeces.D-values and trend values were calculated from the thermal death curves.