Topic
Urea
About: Urea is a research topic. Over the lifetime, 21394 publications have been published within this topic receiving 382444 citations. The topic is also known as: carbamide & carbonic acid diamide.
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TL;DR: Cyanate accumulation was prevented by storage of neutral solutions of urea (prepared at temperatures not exceeding 25°) at 5°, or by buffering the urea solutions at pH 4.7.
91 citations
TL;DR: Alterations in nu1 conformation were examined using hydrodynamic methods, thermal denaturation, circular dichroism, reactivity of histone thiol groups to N-ethyl maleimide, and electron microscopy, and the core protein structure revealed cooperative destabilization between 4 and 7 M urea.
Abstract: Monomer chromatin nu bodies (nu1) from chicken erythrocyte nuclei were exposed to 0-10 M urea plus 0.2 mM EDTA (PH 7). Alterations in nu1 conformation were examined using hydrodynamic methods (i.e., S, eta, and (formula: see text)), thermal denaturation, circular dichroism, reactivity of histone thiol groups to N-ethyl maleimide, and electron microscopy. The two domains of a nu body (i.e., the DNA-rich shell and the protein-rich core) aeared to respond differently to the destabilizing effects of increasing urea; DNA conformation and stability exhibited noncooperative changes; the core protein structure revealed cooperative destabilization between 4 and 7 M urea. Companion studies on the conformation of the inner histone "heterotypic tetramer" also revealed cooperative destabilization with increasing urea concentration.
91 citations
TL;DR: Propionic acid, sodium propionate, benzoic acid and ammonia were the best anti-fungal compounds, followed by urea and citric acid, and clove oil was the best followed by turmeric, garlic and onion.
91 citations
TL;DR: In those cases where TMAO increases enzymatic activity, it did so to the same relative degree, whether or not urea was present, indicating that it does favor compact protein structures.
91 citations
TL;DR: It was thought that useful information might be obtained by studying electrolyte excretion during severe osmotic diuresis, utilizing the clearance technics at present available and results obtained seemed to justify the experimental procedure.
Abstract: N ACCURATE description of the intrinsic renal mechanisms involved in A the excretion of sodium has been difficult to obtain because of the errors inherent in the available experimental technics. Measurements reveal that less than one per cent of the filtered sodium is excreted by man in the normal state of fluid and electrolyte balance (I). Any attempt to define variations of sodium excretion in terms of changes in renal blood flow, glomerular filtration rate or tubular activity, would, of necessity, require analytical and experimental procedures with a combined error of less than one per cent. As such an accuracy is not readily obtainable in the study of the normal state, it is diffiuclt if not impossible to distinguish between analytical errors and physiological variations in calculations designed to show changes in the intrinsic renal processes. It was therefore thought that useful information might be obtained by studying electrolyte excretion during severe osmotic diuresis, utilizing the clearance technics at present available. Under such circumstances, the combined technical errors would be relatively small if large changes in water and electrolyte excretion were demonstrated, thus permitting a quantitative description of the interrelationships of the changes observed. Experiments were performed on dogs subjected to extreme diuresis by the intravenous administration of 50 per cent urea solutions. The results obtained seemed to justify the experimental procedure as they uniformly revealed phenomena interpreted as showing that sodium is reabsorbed by an active process in the proximal tubule, and that water back diffuses as a result of the osmotic gradient thereby established. In independent studies on mannitol diuresis in the dog, Wesson and Anslow (2) ha.ve come to a similar conclusion regarding the nature of the reabsorption of sodium. However, certain differences in the interpretations of the results of the two studies will be discussed.
91 citations