Methods are described for the estimation of plasma and urine alpha-amino nitrogen by the colorimetric ninhydrin reaction; in the method for urine, both ammonia and urea are separated by a rapid ion-exchange resin procedure. Two methods of estimation are given; one has the advantage of great simplicity, but involves the use of cyanide; in the other, cyanide is eliminated. Normal values are repor...

Although many methods for the determination of urea nitrogen have been described, few have proved highly convenient for the accurate determination of small amounts of urea nitrogen without having to make use of special apparatus or techniques. Among the older methods, the Van Slyke gasometric method (1) is generally considered the most accurate, with an allowable error of 1 per cent. This metho...

This study confirms in humans an age-related increase in plasma urea levels (r = 0.62; P < 0.001; y = 0.229x + 18.26) and no correlation between plasma creatinine and age (r = 0.06; NS). Fractional urea excretion (FE urea) decreases with age (r = -0.41; P < 0.001; y = -0.226x + 55). Comparing urea and creatinine clearances, measured in 19 young and in 15 old women, a larger decrease of urea cle...

Patients with severe uremia may have a bleeding tendency associated with a prolonged bleeding time and an adequate platelet count. We have tested the effects on platelet aggregation of three compounds that are found in increased concentration in the blood of patients with renal failure. The addition of urea was followed by an immediate, but transient, increase in optical density of platelet-ric...

• The metabolism of excess dietary protein results in high plasma urea nitrogen (PUN) concentrations • High PUN concentrations (and ammonia to a lesser extent) are associated with decreased fertility in lactating dairy cows • High PUN concentrations probably affect fertility via direct toxic effects on the oocyte and embryo, alterations in the uterine environment and decreased progesterone secr...

Introduction L-Arginine is a semi-essential amino acid involved in numerous areas of human physiology, including production of nitric oxide (NO) – a key messenger molecule involved in vascular regulation, immune activity, and endocrine function. Arginine is also involved in protein production, wound healing, erectile function, and fertility. Arginine is not considered essential because humans c...

Introduction L-Arginine is a semi-essential amino acid involved in numerous areas of human physiology, including production of nitric oxide (NO) – a key messenger molecule involved in vascular regulation, immune activity, and endocrine function. Arginine is also involved in protein production, wound healing, erectile function, and fertility. Arginine is not considered essential because humans c...

A monitoring program with a weekly sampling frequency over a 15-month period indicates that urea concentrations above a certain threshold level may trigger the blooms of Alexandrium catenella in Thau lagoon. However, urea concentrations were also sometimes related to ammonium and dissolved organic nitrogen concentrations, indicating that the role of urea may not be a direct one. An original app...

According to the usually accepted concept, the urea removed from the blood by the kidneys is excreted in two forms, chiefly as urea itself, but partly as ammonia. That the ammonia of the urine is formed in the kidneys was demonstrated by Nash and Benedict (1921), in work which has been confirmed by other authors (cf. Peters and Van Slyke, I, p. 373). Evidence from animal experiments in v4vo has...

BACKGROUND: Animal breeds are often recognized through their specific characteristics, nevertheless, the breeds' anatomical and biochemical characteristics have not considered yet in many of the researches done on one-humped camels. There are some particular differences in camel breeds due to different climate conditions and rearing necessity. OBJECTIVES: The aim of the current study was to com...