5-L-oxoprolinuria and glycine sufficiency.
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Acetaminophen↗
Biomedical subjects
C Persaud
Publications and source records attributed to C Persaud.
The effect of the level of dietary protein, carbohydrate and fat on urea kinetics in young children during rapid catch-up weight gain.
The kinetics of urea metabolism were measured in children recovering from severe malnutrition. For a period of up to 10 d they received one of four diets which provided 711 kJ (170 kcal)/kg per d. Two groups received a diet with a high protein:energy (P:E) ratio of 10-6% (HP), enriched with either fat (HP/F) or maize starch and sucrose (HP/C). Two groups received a diet with a low P:E ratio of 8.8% (LP), enriched with either fat (LP/F) or maize starch and sucrose (LP/C). The rate of weight gain on the HP diets was significantly greater than on the LP diets. There was no difference in urea production between any of the four diets: HP/F 1.23 (SE 0.12), HP/C 1.37 (SE 0.14), LP/F 1.64 (SE 0.22), LP/C 1.15 (SE 0.15) mmol nitrogen/kg per h. On the HP diets urea excretion was 0.77 (SE 0.07) mmol N/kg per h, 61% of production. There was significantly less urea excreted in the urine on diet LP/C than on LP/F (0.36 (SE 0.05) and 0.64 (SE 0.04) mmol N/kg per h respectively). A significantly greater percentage of the urea production was hydrolysed on the LP diets (61%) compared with the HP diets (39%), with the consequence that 50% of urea-N produced was available for synthetic activity on the LP diets compared with 30% on the HP diets. The increase in the urea hydrolysed on the LP diets was equivalent in magnitude to the decreased intake of N, so that overall intake plus hydrolysis did not differ between the LP and the HP diets. Crude N balance was similar on diets HP/F, HP/C and LP/C, but was significantly reduced on diet LP/F. These results show that there is an accommodation in urea kinetics during rapid catch-up weight gain, which becomes evident when the P:E ratio of the diet falls to 8.8%. It is proposed that, for a P:E ratio of 8.8%, protein is limiting for catch-up growth. When the intake has a P:E ratio of 8.8% the pattern of urea kinetics can be modified by the relative proportions of fat and carbohydrate in the diet. The measurement of urea kinetics provides a useful approach to the definition of the adequacy of the protein in the diet.
Child, Preschool↗
Protein turnover and thermogenesis in response to high-protein and high-carbohydrate feeding in men.
The rates of energy expenditure and wholebody protein turnover were determined during a 9-h period in a group of seven men while they received hourly isocaloric meals of high-protein (HP) or high-carbohydrate (HC) content. Their responses to feeding were compared with those to a short period of fasting (15-24 h). The 9-h thermic response to the repeated feeding of HP meals was found to be greater than that to the HC meals (9.6 +/- 0.6% vs 5.7 +/- 0.4% of the energy intake, respectively, means +/- SEM, p less than 0.01). The rate of whole-body nitrogen turnover over 9 h increased from 17.6 +/- 2.2 g on the fasting day to 27.4 +/- 1.4 g during HC feeding (NS) and there was a further increase to 58.2 +/- 5.3 g resulting from HP feeding (p less than 0.001). By using theoretical estimates (based upon ATP requirements) of the metabolic cost of protein synthesis, 36 +/- 9% of the thermic response to HC feeding and 68 +/- 3% of the response to HP feeding could be accounted for by the increases in protein synthesis compared with the fasting state.
Adult↗
The excretion of 5-oxoproline in urine, as an index of glycine status, during normal pregnancy.
The urinary excretion of 5-oxoproline, which may be used as an index of glycine status, was investigated in 30 normal pregnant women during different stages of pregnancy and in 18 non-pregnant female volunteers. During an 18-h study there was little variation in the 5-oxoproline/creatinine index, and a single sample gave a representative value. The excretion of 5-oxoproline/creatinine (mumol/mmol) rose progressively as pregnancy advanced (non-pregnant mean 10, SD 5, first trimester mean 46, SD 12, second trimester mean 150, SD 180, and third trimester mean 280, SD 320) and by the third trimester was over 20 times greater than in non-pregnant women. The data suggest that as pregnancy advances the endogenous production of glycine may be insufficient to satisfy the increasing demands.
Female↗
Urinary excretion of 5-oxoproline (pyroglutamic aciduria) as an index of glycine insufficiency in normal man.
1. The evidence is accumulating to suggest that glycine, the simplest amino acid, is conditionally essential in man. Benzoic acid, by conjugation with glycine to form hippuric acid, is known to deplete the free glycine pool of the body. Glycine is one substrate for the enzyme glutathione synthase (EC 6.3.2.3) and in the inborn error of metabolism in which glutathione synthase function is defective, increased quantities of 5-oxoproline are excreted in the urine. 2. An oral dose of 4-10 g sodium benzoate was given to six normal adults to deplete the metabolic pool of glycine, and the urinary excretion of 5-oxoproline was followed for 6 h. In five of the six, a significant increase in the urinary 5-oxoproline was seen within 3 h. 3. These findings show that 5-oxoprolinuria can result from limited glycine availability, and may provide a useful test for assessing glycine sufficiency in a range of physiological and pathological states.
Adult↗
Whole-body protein turnover in man determined in three hours with oral or intravenous 15N-glycine and enrichment in urinary ammonia.
Studies were carried out in eight normal adults to simplify the continuous infusion-end product method for measuring whole-body protein turnover using 15N-glycine. When a priming dose of label suitable for the urea pool was followed by intermittent oral doses of label, plateau enrichment was maintained in urinary urea and ammonia from 9 to 18 h, giving values for nitrogen flux (18 h) of 0.69 +/- 0.05 g N/kg/d with urea and 0.46 +/- 0.01 g N/kg/d with ammonia. With a priming dose appropriate for the ammonia pool, plateau was reached in urinary ammonia in less than 120 min and maintained for up to 6 h. Nitrogen flux (3 h) with oral 15N-glycine was 0.96 +/- 0.12 g N/kg/d, and with intravenous label was 0.61 +/- 0.13 g N/kg/d. There was a significant linear relationship between flux measured with oral and intravenous isotope. It is suggested that different components of protein turnover are measured with the different approaches, and that the short method in particular measures rapidly turning over proteins associated with the gastrointestinal tract.
Adult↗
Whole-body protein turnover in Jamaican women during normal pregnancy.
A cross-sectional study was carried out among 18 Jamaican pregnant women divided into three groups of 6 subjects according to the stage of pregnancy: group B, 12 weeks, group C, 24 weeks and group D, 33 weeks. A group (group A) of 6 non-pregnant women was selected as control. The rate of whole-body protein turnover was measured by continuous oral administration of 15N-glycine and the resting metabolic rate by the open-circuit method. All subjects had a normal pregnancy outcome. The composition of the diet on the day of the study was comparable between the four groups (approximately 80 g protein and 9.45 MJ energy) and not significantly different from the composition of the diet during the 2 d prior to the experiment. The rates of protein synthesis and breakdown were higher in groups B and C compared to group A and lower in group D where they reached values slightly higher than in group A. Estimated from urea enrichment, these rates did not vary significantly among the groups, while estimated from ammonia enrichment the difference was significant (P less than 0.05) and there was a negative correlation between the gestational age and the rate of synthesis (r = -0.63) and breakdown (r = -0.69). Nitrogen retention was comparable between the three groups of pregnant women and significantly higher than in the group A. The resting metabolic rate was similar between the groups of pregnant women. These results suggest that the rates of protein turnover observed during gestation reflect more the changes that occur in maternal than those in fetal tissues. The values for protein synthesis and nitrogen retention indicate that the amount of protein deposited during pregnancy is greater than that expected on the basis of body composition analysis. It is also suggested that as pregnancy proceeds whole-body protein turnover represents a smaller part of the resting metabolic rate.
Adult↗
Hyperinfection syndrome with Strongyloides stercoralis in malignant lymphoma.
Hyperinfection with Strongyloides stercoralis occurred in three patients with malignant lymphoma. The probable cause in each case was alteration of the immune responses either as a result of the malignant lymphoma or by the treatment given. Though thiabendazole (Mintezol) has produced reasonable results in the treatment of the hyperinfection syndrome, preliminary data suggest that the new broad-spectrum anthelmintic levamisole (Ketrax) is more effective. All patients who live or have lived in an area where strongyloidiasis is endemic should be investigated to detect the presence of the nematode before and during treatment with drugs with immunosuppressive properties. In view of the high mortality with S. stercoralis hyperinfection, vigorous therapy should be instituted before the use of immunosuppressive drugs.
Adult↗