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Biomedical subjects

U Wendel

Publications and source records attributed to U Wendel.

At least 109 records · Page 6Linked to original sources
PubMed1990

Age-dependent fatty acid composition of erythrocyte membrane phospholipids in healthy children.

The fatty-acid composition of red-cell-membrane phospholipids (total phospholipids, phosphatidylcholine, and phosphatidylethanolamine fractions) was determined in 88 apparently healthy children aged 1 to 15 years, 10 cord blood samples, and 6 infants below 1 year of age. The major aim of the study was to determine the normal ranges of fatty-acid proportions, including trans- and odd-numbered fatty acids, for further studies of nutritional and metabolic disorders. The concentrations of most fatty acids of the phospholipids analyzed increased or decreased after birth and assumed adult levels before the second year of life, alpha-linolenic acid (C18:3n - 3) and trans fatty acids, however, continued to increase with age until late childhood.

Adolescent↗
PubMed1990

Six-year follow up of phenylalanine intakes and plasma phenylalanine concentrations.

The daily Phe intakes of normally growing 1- to 6-year-old treated PKU patients were evaluated. The children received protein in amounts that varied from 2.26 +/- 0.47 g/kg body weight per day (mean +/- SD) at the age of 6 to 1.81 +/- 0.35 at the age of 72 months. Mean Phe intakes declining from 34 +/- 7 at the age of 6 months to 15 +/- 5 mg/kg body weight per day at the age of 72 months were required to maintain mean median plasma Phe levels around 6.0 mg/dl.

Aging↗
PubMed1990

[Diagnostic differentiation between precocious puberty and premature thelarche using ultrasonography and the stimulated LH/FSH quotient].

True precocious puberty represents a serious developmental disorder necessitating immediate therapeutic measures, whereas premature thelarche is a harmless variation from the norm. For the differential diagnosis the ultrasonographic evaluation of the internal genitalia is of value. Girls with precocious puberty reveal a statistically significantly greater uterus length and volume as well as ovarian size. The stimulated LH/FSH quotient allows verification of the diagnosis. This value is found always to be greater than 1 in precocious puberty and always less than 1 in premature thelarche.

Adolescent↗
PubMed1990

[Wolman's disease in an infant].

Wolman's disease is a rare inherited disorder of lipid metabolism in which large amounts of triglycerides and cholesteryl esters accumulate in the visceral organs. The main clinical features of the infantile form of the disease are failure to thrive, vomiting and diarrhoea, hepatosplenomegaly and radiological evidence of calcification of the adrenals. We were able to follow the course of this disease in a female turkish infant. It was first admitted because of a transient swelling within the right angle of mandible, subfebrile temperatures and abdominal distension as well as vomiting at the age of three days. After symptomatic treatment she was discharged home without a specific diagnosis. At the age of 4.5 months she was readmitted with severe hepatosplenomegaly, hypochromic anemia and fever of unknown origin. Calcifications of the adrenals and lymphocytic vacuoles led to the diagnosis of Wolman's disease. Deficiency of acid lipase activity in leucocytes could establish this diagnosis.

Adrenal Gland Diseases↗
PubMed1989

Analysis of maple syrup urine disease in cell culture: use of substrates.

Branched-chain 2-oxo acid dehydrogenase activity in human skin fibroblasts against L-leucine, L-valine, L-isoleucine and derived 2-oxo acids was compared in incubations with 1 mmol/l of 1-14C-labelled substrate. The results suggested that the amino acids are the more suitable substrates for an estimation of decarboxylation activity in intact cells. In control cell lines (n = 12), 14CO2 release from amino acids was highest for valine and least for leucine. In a representative number of fibroblast strains of patients with different forms of MSUD (n = 11; residual decarboxylation activity 2-60% of the controls), 14CO2 release from the different amino acids was reduced to a similar degree. Additional measurement of 2-oxo[1-14C]acid release suggested that substrate supply to the branched-chain 2-oxo acid dehydrogenase complex was not rate limiting in the cell lines under investigation.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1989

A convenient enzymatic method for the determination of 4-methyl-2-oxopentanoate in plasma: comparison with high performance liquid chromatographic analysis.

A simple and rapid spectrophotometric method for the estimation of 4-methyl-2-oxopentanoate in plasma samples by use of NAD+-dependent D-2-hydroxyisocaproate dehydrogenase from Lactobacillus casei ssp. pseudoplantarum is described. It is based on the kinetic measurement of the decrease of NADH absorbance at 334 nm. Applicability is demonstrated by comparative measurement of 4-methyl-2-oxopentanoate content in plasma of patients with maple syrup urine disease by the enzymatic and a reversed phase high performance liquid chromatographic method.

Alcohol Oxidoreductases↗
PubMed1989

DNA haplotype analysis at the phenylalanine hydroxylase locus in the Turkish population.

Thirty-nine Turkish phenylketonuria (PKU) families were investigated for their DNA haplotypes at the phenylalanine hydroxylase (PAH) locus. There was a threefold higher incidence of consanguinity in the population studied compared with the general Turkish population. The PAH DNA haplotype 6 was found to be almost exclusively associated not only with the mutant PAH genes but also with the classic phenotype in 39% of the Turkish patients. This haplotype was of not importance in northern European populations. The two DNA haplotypes (1 and 4) that were almost equally frequent among the normal and the mutant PAH genes in northern European populations show virtually the same distribution in Turkish individuals. In all populations studied, these haplotypes are associated with different phenotypes.

Blotting, Southern↗
PubMed1989

Ornithine transcarbamylase deficiency in a male: strict correlation between metabolic control and plasma arginine concentration.

In a male with a partial defect of ornithine transcarbamylase (OTC) we observed that maintenance of arginine supply was crucial for adequate metabolic control in conjunction with a low protein diet. The arginine supplement had to be given such that the concentrations of arginine and ornithine in plasma were above 50 mumol/l. It appears that arginine is needed not only as an essential amino acid for protein synthesis but also as a precursor of ornithine. In this patient the substitution thus aimed at increasing the intramitochondrial ornithine in order to reach a critical substrate concentration for the kinetically abnormal OTC.

Amino Acid Metabolism, Inborn Errors↗
PubMed1989

Monitoring of phenylketonuria: a colorimetric method for the determination of plasma phenylalanine using L-phenylalanine dehydrogenase.

A simple, rapid, accurate, and precise colorimetric assay for the determination of L-phenylalanine in plasma samples using L-phenylalanine dehydrogenase [L-phenylalanine:NAD+-oxidoreductase (deaminating)] from Rhodococcus sp. M 4 is described. The enzyme catalyzes the NAD-dependent oxidative deamination of L-phenylalanine. However, the equilibrium of reaction favors L-phenylalanine formation. By stoichiometric coupling of this reaction with diaphorase/iodonitro tetrazolium chloride (INT) the formed NADH converts INT to a formazan whereby the reaction is displaced in favor of phenylpyruvate. Using a kinetic approach the increase in absorbance at 492 nm shows linearity over more than 30 min. Deproteinized standard solutions of L-phenylalanine in the range from 30 to 1200 mumol/liter show a linearity between the dAformazan/30 min and the substrate concentration. In phenylketonuria (PKU) plasma samples no interferences caused by L-tyrosine or phenylpyruvic acid are seen. Applicability is demonstrated by comparative determination of plasma L-phenylalanine of treated PKU patients by the colorimetric method and automated amino acid analysis.

Amino Acid Oxidoreductases↗
PubMed1989

Functional differences in the catabolism of branched-chain L-amino acids in cultured normal and maple syrup urine disease fibroblasts.

Possible functional differences in the catabolism of the four branched-chain L-amino acids in maple syrup urine disease were assessed using cultured human skin fibroblast stains. Transamination and oxidative decarboxylation were comparatively studied in 90-min incubations with 1 mmole/liter of 1-14C-labeled substrates. In normal cell strains (n = 5), apparent transamination rates (sum of branched-chain 2-oxo[14C]acid and 14CO2 release; means expressed in nmole/90 min/mg of cell protein) were in the order L-leucine (32) greater than L-valine (17) greater than or equal to L-isoleucine (14) greater than L-allo-isoleucine (8); 14CO2 production was in the order L-valine (9) greater than L-isoleucine (6) greater than or equal to L-leucine (5) greater than L-allo-isoleucine (2). In variant (n = 5) as well as classical (n = 2) MSUD cell lines, branched-chain 2-oxo-[14C]acid release rates were generally comparable to the control values. As compared to the 14CO2 release in controls (= 100%), branched-chain 2-oxo acid dehydrogenase activity in MSUD fibroblasts was individually reduced and varied considerably between strains (residual activity 2-38%). Within individual strains, only small differences in the residual decarboxylation activity were observed in incubations with L-valine, L-leucine, and L-isoleucine. It was remarkably high, however, when L-allo-isoleucine was applied as a substrate. With the exception of L-allo-isoleucine, apparent total transamination rates of branched-chain L-amino acids were therefore distinctly lower in MSUD cells than in normal cells.

Amino Acids, Branched-Chain↗
PubMed1989

Interrelation between the metabolism of L-isoleucine and L-allo-isoleucine in patients with maple syrup urine disease.

The nonprotein amino acid L-allo-isoleucine is formed endogenously in maple syrup urine disease patients from (R)-3-methyl-2-oxo-pentanoic acid. During strict metabolic balance, the plasma L-allo-isoleucine/L-isoleucine ratio correlates inversely with the residual activity of the branched-chain 2-oxoacid dehydrogenase in fibroblasts and thus constitutes a relevant in vivo parameter of the severity of the metabolic defect in MSUD patients.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1989

Abnormality of odd-numbered long-chain fatty acids in erythrocyte membrane lipids from patients with disorders of propionate metabolism.

In propionic acidemia and methylmalonic aciduria, disorders of propionate catabolism, excess intracellular propionyl-CoA leads to an enhanced synthesis of odd-numbered long-chain fatty acids. Red cell membrane lipids of patients with these disorders contain pentadecanoic, heptadecanoic, and heptadecenoic acids in excess of normal levels. The odd-numbered long-chain fatty acid content may reflect individual differences in severity of these disorders as well as the degree of effective dietary control. It might be a useful long term parameter for determining the effectiveness of clinical management.

Adolescent↗
PubMed1989

Plasma tocopherol and tocopherol to lipid ratios in a normal population of infants and children.

The plasma tocopherol concentrations were measured by HPLC in 73 apparently healthy West German children aged from 1 to 14 years and in 7 cord blood samples and 5 infants below 1 year of age. Total tocopherols ranged from 584 to 2024 micrograms/dl in the children above 1 year of age (mean 1046 +/- 283 micrograms/dl) and from 511 to 1155 micrograms/dl in the infants below 1 year of age (mean 879 +/- 270 micrograms/dl). The total tocopherol/total lipid ratio-representing the reliable index for vitamin E status-was far above 0.6 mg/g lipid, a level which is regarded as the lower limit of normal (range 1.23 to 4.09 mg/g total lipid in the older children and 1.52 to 2.05 in the infants below 1 year). A positive correlation was found between plasma lipids and total tocopherol (r = 0.71). Our investigation demonstrated an excellent vitamin E status in the children investigated which is considered to reflect the high supply of West German food with PUFA and vitamin E.

Adolescent↗
PubMed1988

Analysis of the fatty acid composition of erythrocyte phospholipids by a base catalysed transesterification method--prevention of formation of dimethylacetals.

A sensitive method for the analysis of the fatty acid composition of erythrocyte phospholipids with capillary column GLC is described. Under the assay conditions (base catalysed transesterification with sodium methoxide), only the fatty acids of the phospholipids are converted to their methylesters. The alkenyl ether chains of the plasmalogens are not transmethylated. This eliminates the need for thin layer chromatography for the separation of dimethylacetals and esterified fatty acids. The method is suitable for the measurement of the fatty acid patterns of erythrocyte phospholipids in small blood samples.

Acetals↗
PubMed1988

Prevalence of coeliac disease in diabetic children and adolescents. A multicentre study.

Screening for coeliac disease (CD) with serum antigliadin antibodies (AGA) was performed in 1032 diabetic children and adolescents. In 8 children CD had been diagnosed before study entry. Of the remaining 1024 children, 33 had an elevated AGA titre in the first serum sample. On follow-up an elevated AGA titre was confirmed in only 17 of 31 patients. Nine of the repeatedly positive patients underwent jejunal biopsy, and CD was diagnosed in two asymptomatic patients; both were positive for IgG- and IgA-AGA. Among 10 AGA-positive patients in whom biopsies could not be performed, only 1 showed IgA-AGA and thus carried a high risk for CD. From our results we estimate a prevalence of CD in Swiss and German diabetic children between 1.1% and 1.3%. False-positive AGA titres occurred significantly more often in patients with diabetes duration of less than 1 year. AGA testing reached a specificity of 99% if performed at least 1 year after the onset of diabetes. Children suffering from both diabetes and CD showed a diabetes manifestation at a significantly younger age than non-coeliac patients, whereas CD tended to be diagnosed at a remarkably late age.

Adolescent↗
PubMed1988

DNA analysis of ornithine transcarbamylase deficiency.

By analysing the restriction fragment length polymorphism (RFLP) detected by an ornithinetranscarbamylase (OTC) gene specific DNA probe, we followed the segregation of the defective gene in two families with OTC deficiency (X-linked disease). We were able to exclude some female family members as carriers. In one case a doubtful result obtained in a biochemical carrier detection test (by examining the renal orotic acid excretion after a protein load) could be clarified by DNA analysis. In every family with OTC deficiency, carrier detection should be biochemical with additional DNA analysis. Previous results of the biochemical carrier test should be controlled by DNA analysis, especially when "normal" results were obtained.

Amino Acid Metabolism, Inborn Errors↗