System In Various Forms Research Articles

Studies on the Renin-angiotensin System in Younger Hypertensives

The renin-angiotensin system in various forms of hypertension in younger adults, refractory edema and normal controls was studied by measurement of serum renin, of serum angiotensinase and angiotensin infusion test. The attitudes of the renin-angiotensin system in renovascular hypertension, malignant hypertension and primary aldosteronism were significantly different from that in normal controls. The renin-angiotensin system in refractory edema without hypertension was similar to that in renovascular hypertension. In hypertension with unknown cause, subjects with hypertensive disposition showed increased pressor response to angiotensin infusion in spite of normal levels of serum renin. The studies on the renin-angiotensin system by these examinations are useful for differentiation of various forms of hypertension.

Photography of Neutron Diffraction Patterns

Photography of slow neutron radiation can be accomplished through use of fluorescent screens in which secondary radiation (beta particles, gamma rays, or visible light) is used to produce photographic action. Thus, as part of a comprehensive study on screen-film combinations, a study is made of the sensitivity and spatial resolution of Li/sup 6/ metal-zinc sulfide systems and Li/ sup 6/F-- ZnS systems in v-arious forms of combination. Hence, the relative neutron exposures required for the different screens to produce a photographic density of 0.5 on Tri-X film with monochromatic neutrons of wavelength 1.5 A are tabulated. It is seen that the homogeneously-mixed screen is more sensitive by an order of magnitude than the heterogeneous screens. Results are also given which show the screen response as a function of mixing ratio (ZnS to Li/sup 6/F) for different neutron wavelengths and an optimum weight ratio of about 4 is suggested. (N.W.R.)