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Biomedical subjects

W Heine

Publications and source records attributed to W Heine.

At least 73 records · Page 4Linked to original sources
PubMed1985

[Determination by 15N tracer kinetics of the half-life of total body protein in premature and mature infants].

Based on 15N-tracer techniques important data of the intermediary protein metabolism can be assessed by compartment analysis. We calculated the half-life of whole body proteins in five preterm and five full term infants in addition to commonly used parameters of the protein metabolism e.g. protein synthesis rate, protein breakdown rate, N-turnover rate, size of metabolic pool, half-life and reutilization of aminoacid-N and the rate of endogenous urinary-N. The infants were aged 27 +/- 4 and 31 +/- 13 days resp. The half-life of whole body proteins were found to be 7.5 +/- 1.8 days in the premature infants and thus significantly shorter than the 16.0 +/- 3.8 days for the full term infants. The differences in the half-life of protein as well as protein synthesis rate and protein breakdown rate reflect the rapid proteinturnover in premature infants in comparison to full term infants.

Amino Acids↗
PubMed1985

15N-tracer-kinetic studies on the nitrogen metabolism of very small preterm infants on a diet of mother's milk.

Protein synthesis and breakdown, nitrogen flux and other parameters of nitrogen metabolism were measured in five male preterm infants with a mean gestational age of 30.4 +/- 1.95 complete weeks of gestation and a mean body weight of 1592 +/- 517 g. The infants were fed on mothers' milk; the measurements were made at a post-conceptional age of 31.6 +/- 1.9 weeks of gestation (Ia) and were repeated at 34.4 +/- 1.9 weeks of gestation (Ib). [15N]-glycine (95 atom per cent) was used as a tracer, administered as a single enteral dose of 20 mg/kg. Whole-body protein parameters were calculated from an assumed three-pool model. The results were compared with data from moderately small preterm (II) and full-term (III) infants measured at post-conceptional ages of 36.1 +/- 1.4 and 48.0 +/- 2.8 weeks respectively. Protein synthesis rates tended to decrease with increasing post-conceptional age: 14.3 +/- 4.5 g/kg/d (Ia); 11.8 +/- 2.9 g/kg/d (Ib); 7.9 +/- 2.7 g/kg/d (II); and 7.7 +/- 1.4 g/kg/d (III). Protein breakdown and nitrogen flux showed the same trends. Possible consequences for the appropriate nutrition of very small preterm infants are discussed.

Birth Weight↗
PubMed1984

Urea utilization by the intestinal flora, of infants fed mother's milk and a formula diet, as measured with the 15N-tracer technique.

15N-Incorporation by intestinal bacteria was measured under different feeding conditions in 16 infants after a single oral loading of 165 mg [15N2]urea X kg-1 body weight as a tracer. In five subjects on a mother's milk diet, the 15N-excess in the isolated intestinal bacteria was 1.08 (0.17-1.85) atom-%. The mean 15N-excess in the intestinal flora of five formula-fed subjects did not differ significantly from these values [0.63 (0.17-1.05) atom-%]. A trend to a higher incorporation of 15N from labeled urea by the intestinal flora was seen in four infants, who were adapted to an increased nutritional urea supply on a special formula, containing 14 g of milk protein, 80 g lactose, 36 g fat, and 0.35 g urea X L-1. The same observation was made in two infants with chronic renal failure. The incorporation of urea nitrogen by the putrefactive intestinal flora of infants on a formula diet as well as by the bifidobacterial flora of those on mother's milk feeding indicates the utilization of ureas as a source of bacterial protein and nucleic acid synthesis. The adaptive usage of urea for the bacterial metabolism can be considered as a sign of supportive detoxification by the intestinal flora.

Bacteria↗
PubMed1984

[Rett syndrome].

Explore the source record for details and available documents.

Ammonia↗
PubMed1983

D-amino acid utilization in infants measured with the 15N-tracer technique.

The utilization rates of D-[15N] valine, D-[15N] leucine, D-[15N] phenylalanine and D-[15N] alanine were investigated in seven infants being fed parenterally. Retention of the (15)N in the protein pool varied from one amino acid to another and ranged from 23.2% for D-[15N] valine to 48.6% for D-[15N] alanine. In the case of valine it was shown that cumulative renal excretion amounted to 70% of the applied (15)N-dose, 44% being overflow of unchanged D-[15N] valine, 16.6% appearing as [15N] urea and 1.2% as [15N] ammonium. This indicates that doubling the concentrations of D-amino acid racemates compared with their L-isomer counterparts in parenteral feeding solutions must inevitably lead to imbalances. The use of D-amino acids for the purposes of parenteral nutrition remains however ineffective due to their poor and variable utilization compared to L-amino acids.

Journal Article↗
PubMed1983

Evaluation of different 15N-tracer substances for calculation of whole body protein parameters in infants.

The validity of using different 15N-tracer substances to measure whole body protein parameters, i.e., protein synthesis, protein breakdown, net protein gain, protein turnover, metabolic pool, and reutilization, was assessed by comparing the results obtained with: [15N]glycine, a mixture of 10 15N-labeled amino acids, and a 15N-labeled chicken egg protein in two infants, 9 and 12 weeks old, who were fed human milk. The tracer substances were fed orally as a single dose corresponding to a 15N-excess quantity of 0.2 mmol X kg-1 body weight. 15N Excretion in the urine was measured cumulatively by emission spectrometry, and the data on the protein metabolism were calculated by means of a three-pool model. All three tests yielded consistent net protein gains. The protein synthesis, protein breakdown, protein turnover, and nitrogen reutilization values produced by the [15N]glycine tracer study were higher than those produced by application of the 15N-amino acid mixture and the 15N-labeled egg protein. However, in our opinion, this discrepancy does not justify the replacement of [15N]glycine by expensive 15N-amino acid mixtures as tracer substances.

Amino Acids↗
PubMed1983

15N-tracer investigations into the nitrogen metabolism of preterm infants fed mother's milk and a formula diet.

Protein synthesis, protein breakdown, protein-N turnover, and other parameters describing the nitrogen metabolism were measured in five male preterm infants. The weight of the subjects at birth was 2,064 +/- 107 g and the measurements were performed at age 16.0 +/- 4.5 days in the case of the mother's milk diet and 27.4 +/- 6.8 days in the case of the formula diet containing 1.8% protein. The parameters were measured by means of the 15N-tracer technique using [15N]glycine (95 atom %) applied in a single oral dose of 20 mg/kg as a tracer. The three-pool model proposed by Winkler and Faust was used to calculate the whole body protein parameters. No difference in net protein gain, protein synthesis, protein breakdown, or the other protein metabolism parameters were recorded despite the different protein inputs. Renal nitrogen excretion and the rate of endogenous urea N excretion were significantly higher for the formula diet than for the mother's milk diet. The protein synthesis rate of 7.9 g X kg-1 X day-1 was, as has previously been observed, higher than in other age groups. The protein metabolism of the preterm infant older than 33 weeks of gestational age does not benefit from a formula diet based on cow's milk that is richer in protein than mother's milk.

Glycine↗
PubMed1983

[Value of the histamine liberation test in the diagnosis of intestinal protein intolerance].

The validity of the histamine releasing test for the diagnosis of cow's milk, soy, and egg protein allergy was checked in 31 infants with clinical features of intestinal protein intolerance. The test was positive in 12 of the infants, but in only 5 resp. 1 among them the prick or the Ouchterlony test were pathological. The remaining 19 infants reacted negatively in all 3 tests and subsequently tolerated oral protein loading. The results indicate the superiority of the histamine releasing test in comparison to the conventional prick- and Ouchterlony test.

Animals↗
PubMed1983

15N-labelled yeast protein--a valid tracer for calculating whole-body protein parameters in infants: a comparison between [15N]-yeast protein and [15N]-glycine.

The validity of [15N]-glycine and 15N-labelled yeast protein as tracers for investigating the parameters of nitrogen metabolism in man was studied by comparisons of each tracer in three infants on different diets. Both tracers were administered with the food as a single oral dose of 0.2 mmol 15N-excess nitrogen per kg body weight. Cumulative 15N-excess excretion in the urine was measured by emission spectrometry and a three-compartment model was used to calculate the pool sizes by computer. In all three comparisons the values calculated for protein synthesis, protein breakdown, protein turnover and reutilization after administration of 15N-labelled yeast protein were slightly lower than those calculated after administration of [15N]-glycine. The particular advantage of applying a highly enriched, completely labelled [15N]-protein instead of [15N]-glycine as a tracer is that the protein, containing some 20 amino acids, doubtless gives a more accurate picture of protein metabolism than the use of a single amino acid labelled with heavy nitrogen. However, the small differences between the whole-body parameters calculated from 15N-labelled yeast protein and [15N]-glycine do not justify the general replacement of [15N]-glycine by 15N-labelled protein.

Diet↗
PubMed1982

The effect of oral contraceptives on reproductive function during semichronic exposure to ethanol by the female rat.

1. Female rats were placed on water, 5% ethanol (ET), or 20% ET drinking solutions for 8 weeks. The last 2 weeks, the rats received orally either ethinyl estradiol (EE), norethindrone acetete (NED), or a combination of both. 2. Luteinizing hormone decreased due to ET drinking and was undetectable subsequent to the steroidal treatment. 3. Prolactin increased after steroid treatment and alcohol drinking in the controls. 4. Ethanol (5%) plus EE increased prolactin as did the steroidal combination, whereas ET (20%) likewise increased prolactin in conjunction with NED over water controls. 5. Hepatic alcohol dehydrogenase was inhibited due to EE when compared to water-controls in the 5% ET drinking animal, whereas aldehyde dehydrogenase was induced in combination with NED in both the 5% and 20% ET drinking rats.

Alcohol Oxidoreductases↗