The rate at which urea enters the body pool of urea in sheep was investigated using isotope dilution techniques. Both single injection and constant infusion of carbon-14 urea were used. Urea excretion rates were calculated by measuring the urea in urine collected from a catheter in the bladder. Urea entry and excretion rates were measured in sheep fed rations containing 3.5, 9, 17 and 27% crude...

The urea tests of renal efficiency commonly mentioned in the literature include (a) simple estimation of blood urea concentration, (b) determination of urine urea concentration following ingestion of urea, and (c) observations on the relationship between blood and urine urea concentrations. From a comparative study of these three methods, the general conclusion reached in this hospital (1) was ...

On one side of the urea-secreting cells of the kidney there is blood and on the other side there is urine. The rate of urea excretion is the rate at which these cells transfer urea from blood to urine. Under these circumstances it seems probable that changes in the concentration of urea in the ,blood will have an effect on the rate of urea excretion. If the concentration of urea in the blood we...

throughout the world, millions of muslims fast daily during the month of ramadan from sunrise (sahar) until sunset (iftar). considering the impacts of environment on physiological functions, we performed this study in order to examine the effects of ramadan fasting on some blood parameters of healthy volunteers and hypertensive patients. according to the results, there were no significant chang...

-the cowpea aphid, aphis craccivora koch, is an important pest of robinia pseudoacacia frisia. life table parameters of a. craccivora were determined under natural (16- 33ºc and 32-89% rh, respectively) and laboratory (25 ± 1ºc, rh of 70 ± 5% and a photoperiod of 16:8 h (l: d) conditions. the data were analyzed using the age-stage, two-sex life table theory. each experiment was replicated 45 ti...

life table parameters of aphis pomi degeer (hemiptera: aphididae) were determined on two host plants: apple (malus pumila l.) and flowering quince (chaenomeles japonica lindl.). this study was carried out under laboratory conditions (25 ± 1 ºc and rh of 70 ± 5 % and a photoperiod of 16: 8 h (l: d). the survivorship from first instar nymphs to adult was very close in m. pumila and c. japonica. t...