scholarly journals Urea kinetics in healthy women during normal pregnancy

1997 ◽  
Vol 77 (2) ◽  
pp. 165-181 ◽  
Author(s):  
Irene S. M. McClelland ◽  
Chandarika Persaud ◽  
Alan A. Jackson
Keyword(s):  
Protein Intake ◽  
Late Pregnancy ◽  
Normal Pregnancy ◽  
Urea Hydrolysis ◽  
Urea Excretion ◽  
Urea Production ◽  
Urea Kinetics ◽  
Normal Women ◽  
Oral Doses ◽  
Habitual Protein Intake

Urea kinetics were measured in normal women aged 22-34 years at weeks 16, 24 and 32 on either their habitual protein intake (HABIT.) or a controlled intake of 60 g protein/d (CONTROL), using primed-intermittent oral doses of [15N15N]urea and measurement of plateau enrichment in urinary urea over 18 h (ID) or a single oral dose of [15N15N]urea and measurement of enrichment of urea in urine over the following 48 h (SD). The intake of protein during HABIT-ID (80 g/d) was greater than that on HABIT-SD (71 g/d); urea production as a percentage of intake was significantly greater at week 16 for HABIT-ID than HABIT-SD, whereas urea hydrolysis at week 16 was greater for HABIT-SD than HABIT-ID and urea excretion at week 32 was greater for HABIT-ID than HABIT SD. The combined results for HABIT-ID and HABIT-SD showed a significant reduction in urea production at week 32 compared with week 24. Urea excretion decreased significantly from week 16 to week 24 with no further decrease to week 32 and urea hydrolysis was significantly greater at week 24 than either week 16 or week 32. Compared with HABIT, on CONTROL there was a decrease in urea production at week 16, and urea excretion was significantly reduced at week 16. For all time periods urea production was closely related to the sum of intake plus hydrolysis. Hydrolysis was greatest at week 24 and closely related to urea production. There was a significant inverse linear relationship overall for hydrolysis as a proportion of production and excretion as a proportion of intake. The results show that on HABIT N is more effectively conserved in mid-pregnancy through an increase in urea hydrolysis and salvage, and during late pregnancy through a reduction in urea formation. Lowering protein intake at any stage of pregnancy increased the hydrolysis and salvage of urea. The staging of these changes was later than that in pregnancy in Jamaica.

The 24-h whole body leucine and urea kinetics at normal and high protein intakes with exercise in healthy adults

1998 ◽  
Vol 275 (2) ◽  
pp. E310-E320 ◽  
Author(s):  
Anders H. Forslund ◽  
Leif Hambraeus ◽  
Roger M. Olsson ◽  
Antoine E. El-Khoury ◽  
Yong-Ming Yu ◽  
...  
Keyword(s):  
Protein Intake ◽  
High Protein ◽  
Whole Body ◽  
Body Protein ◽  
Protein Levels ◽  
Adult Men ◽  
Exercise Regimen ◽  
Urea Production ◽  
Urea Kinetics ◽  
Marked Decline

In healthy adult men adapted to a diet/exercise regimen for 6 days, the effects of small, frequent meals supplying daily protein intakes of 1 ( n = 8) or 2.5 g ⋅ kg−1 ⋅ day−1( n = 6) on leucine oxidation, urea production, and whole body protein synthesis (PS) and degradation (PD) have been compared with the use of a 24-h continuous intravenous [13C]leucine and [15N,15N]urea infusion protocol. Two 90-min periods of exercise (∼50% maximal O2 consumption) were included during the fasting and the fed periods of the 24-h day. Subjects were determined to be at approximate energy, nitrogen, and leucine balances on both diets. Increased protein intake raised the urea production rate; the absolute rate of urea hydrolysis was the same on both diets. When the first-pass splanchnic uptake of leucine was taken to be 25% of intake, PS was stimulated by feeding (after an overnight fast) at both protein intake levels ( P < 0.05 and P < 0.01), whereas PD declined significantly ( P < 0.01) at both protein levels. Protein gain at a high protein intake appears to be the result of both a stimulation of PS and a marked decline in PD, whereas at a less generous intake, the gain appears to be a result of a fall in PD with a less evident change in PS. Exercise moderately decreased PS during and/or immediately after exercise at each protein level, and there was a postexercise-induced increase ( P < 0.01) in PD, which was more dramatic when feeding was at the higher protein intake level.

Limits of adaptation to a diet low in protein in normal man: urea kinetics

1992 ◽  
Vol 83 (1) ◽  
pp. 103-108 ◽  
Author(s):  
M. Danielsen ◽  
A. A. Jackson
Keyword(s):  
Production Rate ◽  
Nitrogen Balance ◽  
Healthy Men ◽  
Nitrogen Pool ◽  
Low Protein ◽  
Urea Production ◽  
Urea Kinetics ◽  
Normal Man ◽  
Oral Doses ◽  
Protein Diets

1. Urea kinetics were measured using prime/intermittent oral doses of [15N15N]urea in six healthy men taking diets adequate in energy and containing either 74 or 30 g of protein/day. 2. On 74 g of protein/day, urea production (199 mg of N day−1 kg−1) was 121% of intake, with 60% of the urea produced being excreted in the urine and 40% being salvaged in the colon; 69% of the salvaged nitrogen was retained in the metabolic nitrogen pool. 3. Nitrogen balance was not maintained on 30 g of protein/day. There was a significant decrease in the urea production rate (123 mg of N day−1 kg−1) and 54% of production was excreted in urine, with 46% being salvaged. 4. The pattern of urea production and salvaging on 30 g of protein/day was different to that seen in an earlier study on 35 g of protein/day, with a significant decrease in both production (71%) and salvaging (50%). 5. These data reinforce the conclusions drawn from an earlier study, that the salvaging of urea nitrogen by the colon is an integral part of the process of adaptation to low protein diets. The salvage system appears to fail on an intake of 30 g of protein/day and nitrogen is no longer conserved in sufficient amounts for balance to be maintained. 6. The changes seen in urea kinetics reinforce the conclusion based upon nitrogen balance that the minimum physiological requirement for protein in normal adult man lies between 30 and 35 g of protein/day.

scholarly journals Urea kinetics in healthy young women: minimal effect of stage of menstrual cycle, contraceptivepill and protein intake

1996 ◽  
Vol 76 (2) ◽  
pp. 199-209 ◽  
Author(s):  
Irene S. M. McClelland ◽  
Alan A. Jackson
Keyword(s):  
Menstrual Cycle ◽  
G Protein ◽  
Young Women ◽  
Protein Intake ◽  
Individual Variability ◽  
Contraceptive Pill ◽  
Significant Difference ◽  
Urea Production ◽  
Urea Kinetics ◽  
Habitual Intake

Urea kinetics were measured using prime/lintermittent oral doses of [15N15N]urea, on five separate protocols in thirteen normal young women. Each woman underwent either two or three study protocols.Measurements were made at day 12 and day 22 of the menstrual cycle, whilst consuming their habitual protein intake in seven women not taking the contraceptive pill and in six women taking the contraceptive pill. In three woman taking the pill, and three not taking the pill, urea kinetics were measured whilst taking a diet in which the intakewas restricted to 55 g protein/d. There was no difference in the rate of urea production, urea excretion or urea hydrolysis between the women taking the pill and those not taking the pill at day 22. In the women not taking the pill there was no difference in any measure between day 12 and day 22. In the women taking the pill there was a significant difference in the disposal of urea N to excretion or hydrolysis on day 12 compared with day 22, with a relative decrease in excretion and enhancement of hydrolysis at day 12 compared with day 22. On the restricted diet, an intake of 55 g protein/d represented 77% of the habitual intake and urea production, excretion and hydrolysis were reduced to about 84% of the rate found on the habitual intake. In paired studies the reduction in urea production was statistically significant, and there was a statistically significant linear relationship between urea production and either intake or the sum of intake plus hydrolysis. The within-individual variability for urea production was about 10% for excretion 15% and for hydrolysis 44% The between-individual variability for intake was about 17% on the habitual intake. The variability for production, excretion and hydrolysis (14, 13, 36%) was less in the women not taking the contraceptive pill than in those taking the pill (23,32,42% respectively). The variability was reduced on the controlled low intake of 55 g protein compared with the habitual intake.These results confirm the wide variability in aspects of urea kinetics between individuals. In women this variability is not, to any large extent, accounted for by changes associated with themenstrual cycle

DIE AUSSCHEIDUNG VON TESTOSTERON UND EPITESTOSTERON BEI FRAUEN AM ENDE DER SCHWANGERSCHAFT

1969 ◽  
Vol 60 (4) ◽  
pp. 579-585
Author(s):  
K. Schollberg ◽  
E. Seiler ◽  
J. Holtorff
Keyword(s):  
Urinary Excretion ◽  
Late Pregnancy ◽  
Mean Values ◽  
Pregnant Females ◽  
Female Foetus ◽  
The Mean ◽  
The Difference ◽  
Normal Women ◽  
In Pregnancy

ABSTRACT The urinary excretion of testosterone and epitestosterone by women in late pregnancy has been studied. The mean values of 22 normal women in pregnancy mens X are 12.9 ± 9.2 μg/24 h in the case of testosterone and 16.1 ± 16.2 μg/24 h in the case of epitestosterone. Both values do not differ significantly from those of non-pregnant females. The excretion values of mothers bearing a male foetus (17.3 ± 8.9 μg/24 h) are higher than those of mothers with a female foetus (6.4 ± 4.8 μg/24 h). The difference is statistically significant with P = 0.01.

scholarly journals Higher maternal dietary protein intake in late pregnancy is associated with a lower infant ponderal index at birth

2006 ◽  
Vol 61 (4) ◽  
pp. 498-508 ◽  
Author(s):  
K Andreasyan ◽  
A-L Ponsonby ◽  
T Dwyer ◽  
R Morley ◽  
M Riley ◽  
...  
Keyword(s):  
Dietary Protein ◽  
Protein Intake ◽  
Late Pregnancy ◽  
Ponderal Index ◽  
Dietary Protein Intake

Fibrin monomer complex in normal pregnant women: a potential thrombotic marker in pregnancy

2007 ◽  
Vol 44 (5) ◽  
pp. 449-454 ◽  
Author(s):  
Hiroaki Onishi ◽  
Kimiko Kaniyu ◽  
Mitsutoshi Iwashita ◽  
Asashi Tanaka ◽  
Takashi Watanabe
Keyword(s):  
Pregnant Women ◽  
Late Pregnancy ◽  
Normal Pregnancy ◽  
Reference Ranges ◽  
Vein Thrombosis ◽  
Fibrin Monomer ◽  
Potential Marker ◽  
Deep Vein ◽  
Positive Results ◽  
In Pregnancy

Background: Pregnancy represents a major risk factor for deep vein thrombosis (DVT). Most coagulation/fibrinolysis markers currently utilized change during pregnancy, and therefore they cannot accurately evaluate thrombotic events in pregnancy because the rate of false positive results is high. Fibrin monomer complex (FMC) has recently become widely available for diagnosing DVT. The present study examined whether FMC is suitable for evaluating thrombotic status in pregnancy. Methods: Concentrations of FMC and other haemostatic markers were investigated in 87 pregnant women without major complications at early, mid- or late pregnancy. FMC concentrations were also measured in 127 normal non-pregnant women, and in one woman who developed DVT after delivery. Results: In normal pregnant women, FMC concentrations were unchanged during early or mid-pregnancy and slightly elevated during late pregnancy. Concentrations were within reference range in most cases, and none exceeded the cut-off value for DVT. In contrast, thrombin-antithrombin complex (TAT) and D-dimer (DD) concentrations were significantly elevated in late pregnancy, and median values exceeded reference ranges. The DVT case displayed significantly elevated FMC concentrations. Conclusions: Changes in FMC concentrations during normal pregnancy are minimal compared with other haemostatic markers. Because the rate of false positivity is lower, FMC could be a potential marker of thrombotic status in pregnancy rather than TAT and DD.

Effect of protein intake and physical activity on 24-h pattern and rate of macronutrient utilization

1999 ◽  
Vol 276 (5) ◽  
pp. E964-E976 ◽  
Author(s):  
Anders H. Forslund ◽  
Antoine E. El-Khoury ◽  
Roger M. Olsson ◽  
Anders M. Sjödin ◽  
Leif Hambraeus ◽  
...  
Keyword(s):  
Physical Activity ◽  
G Protein ◽  
Protein Intake ◽  
Healthy Adult ◽  
High Protein Diet ◽  
Positive Energy ◽  
Moderate Physical Activity ◽  
Adult Men ◽  
Urea Production ◽  
Positive Energy Balance

Effects of moderate physical activity (90 min at 45–50% of maximal O2 uptake 2 times daily) and “high” (2.5 g protein ⋅ kg−1 ⋅ day−1, n = 6) or “normal” protein intake (1.0 g protein ⋅ kg−1 ⋅ day−1, n = 8) on the pattern and rate of 24-h macronutrient utilization in healthy adult men were compared after a diet-exercise-adjustment period of 6 days. Energy turnover (ET) was determined by indirect and direct (suit) calorimetry, and “protein oxidation” was determined by a 24-h continuous intravenous infusion of [1-13C]leucine. Subjects were in slight positive energy balance during both studies. Protein contributed to a higher (22 vs. 10%) and carbohydrate (CHO) a lower (33 vs. 58%) proportion of total 24-h ET on the high- vs. normal-protein intake. The highest contribution of fat to ET was seen postexercise during fasting (73 and 61% of ET for high and normal, respectively). With the high-protein diet the subjects were in a positive protein ( P < 0.001) and CHO balance ( P < 0.05) and a negative fat balance ( P < 0.05). The increased ET postexercise was not explained by increased rates of urea production and/or protein synthesis.

Effects of intraruminal infusions of urea, sucrose or urea plus sucrose on plasma urea and glucose kinetics in sheep fed chopped lucerne hay

1993 ◽  
Vol 121 (1) ◽  
pp. 125-130 ◽  
Author(s):  
Y. Obara ◽  
D. W. Dellow
Keyword(s):  
Plasma Glucose ◽  
Rumen Fluid ◽  
Glucose Production ◽  
Ammonia Concentration ◽  
Irreversible Loss ◽  
Glucose Kinetics ◽  
Plasma Urea ◽  
Urea Excretion ◽  
Urea Kinetics ◽  
Plasma Urea Concentration

SUMMARYThe effect of rumen fermentation on the relationship between urea and glucose kinetics was examined in sheep fed chopped lucerne hay with intraruminal infusions of water, urea, sucrose, or urea plus sucrose at Palmerston North, New Zealand in 1986. Sheep were fed hourly and infused intraruminally with water (1200 m1/day), or a similar volume containing either urea alone (13·7g/day), sucrose alone (178·2 g/day) or urea (14·6 g/day) plus sucrose (175·0 g/day). The added sucrose resulted in a lower rumen ammonia concentration (P< 0·05), lower plasma urea concentration (P< 0·05) and reduced urinary urea excretion (P< 0·05). Urea recycled to the gut tended to increase with the sucrose, urea or sucrose plus urea treatments compared with the water treatment. The fermentation of sucrose in the rumen resulted in decreases in ruminal pH (P< 0·05) and in the ratio of acetate to propionate (A:P) (P< 0·05). The infusion of sucrose also increased the concentration of propionate in rumen fluid (P< 0·05), tended to increase the plasma glucose level and increased plasma glucose irreversible loss (P< 0·05). The infusion of urea resulted in an increase in the plasma urea level (P< 0·05), urea pool size (P< 0·05) and urea irreversible loss (P< 0·01). However, urea infusion did not affect glucose metabolism or volatile fatty acid (VFA) fermentation. The effects of sucrose infusion on glucose and urea kinetics were broadly similar when given alone or with urea, apart from changes in the urea degradation rate. It was concluded that the additional fermentative activity resulting from sucrose increased propionate production which, in turn, was available for glucose production, thus ‘sparing’ amino acids for tissue protein utilization and reducing urea excretion.

Reassessment of primed constant-infusion tracer method to measure urea kinetics

1987 ◽  
Vol 252 (4) ◽  
pp. E557-E564 ◽  
Author(s):  
F. Jahoor ◽  
R. R. Wolfe
Keyword(s):  
Steady State ◽  
Constant Infusion ◽  
Dependent Manner ◽  
Tracer Technique ◽  
Tracer Method ◽  
Priming Dose ◽  
Short Term ◽  
Urea Production ◽  
Urea Kinetics ◽  
Dose Dependent

The validity of the primed constant-infusion tracer technique to make short-term measurements of urea production rates (Ra) in humans in a physiological steady state and during disruption of steady state was evaluated. Four subjects received a primed constant infusion (P/I = 560 min) of [13C]urea for 8 h. A plateau in urea enrichment was reached after 2 h and maintained throughout. When [13C]- and [18O]urea were simultaneously infused into four subjects at P/I ratios of 560:1 and 360:1, respectively, both tracers reached plateau enrichment at the same time (2-4 h). The enrichment at plateau was a function of the infusion rate rather than the priming dose, and calculated urea Ra was the same with either prime. In five additional experiments the technique responded acutely to a physiological perturbation (alanine infusion) in a dose-dependent manner. The results confirm that this technique is appropriate for short-term measurements of urea Ra, and the requirement for accuracy in estimating the priming dose is not impractically stringent.

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