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Biomedical subjects

U Langenbeck

Publications and source records attributed to U Langenbeck.

At least 37 records · Page 2Linked to original sources
PubMed1990

A new approach to the newborn screening for hyperphenylalaninemias: use of L-phenylalanine dehydrogenase and microtiter plates.

We adapted the recently described colorimetric method for the specific determination of phenylalanine to a microplate assay using a NAD(H)-dependent L-phenylalanine dehydrogenase. With respect to sensitivity, analytical recovery and interrun imprecision this method for measuring phenylalanine in eluates of paper-dried blood spots is suitable for routine newborn screening for hyperphenylalaninemias. In contrast to the microbiological Guthrie assay, with the enzymatic method quantitative data may be obtained on the same day, also in the blood of newborns on antibiotic treatment.

Amino Acid Oxidoreductases↗
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

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)↗
PubMed1988

Skeletal anomalies in trisomy 21 as an example of amplified developmental instability in chromosome disorders: a histological study of the feet of 21 mid-trimester fetuses with trisomy 21.

In a previous radiographic study on the feet of 71 adults with trisomy 21 we found, in comparison to control individuals, an increased prevalence of biphalangeal toes and metatarsophalangeal sesamoid bones. The present histological study on the feet of 21 mid-trimester fetuses with prenatally diagnosed trisomy 21 confirms results of the earlier study. At both stages of development these minor bone anomalies have about the same frequency, thus suggesting 1) that they are selectively neutral, and 2) that they reflect a basic (innate) failure of ordered morphogenesis. Our observation that the normal spatial pattern of skeletal variants is reproduced in trisomy 21 simply on a quantitatively higher level lends sound support to the hypothesis of amplified developmental instability in chromosome trisomies.

Adult↗
PubMed1986

Hyper-2-oxoglutaric aciduria in long-term mental handicap.

One thousand one hundred and seventy-five mentally retarded patients in an institution (733 males and 442 females) were screened for urinary excretion of 2-oxoacids using a quantitative gas chromatographic method. On follow-up, in 10 out of 31 male patients with excretion of greater than or equal to 50 mmoles 2-oxoglutaric acid per mole creatinine, a previously unrecognized bacteriuria was considered the cause of hyper-2-oxoglutaric aciduria. Of the remaining 21, nine had elevated blood citric acid, and four had borderline elevations of blood pyruvic and/or 2-oxoglutaric acid. In the 11 males with persistent hyper-2-oxoglutaric aciduria an increased incidence of seizure disorders and cerebral palsy relative to the total patient population was found. Hyper-2-oxoglutaric aciduria with concomitant abnormalities of blood metabolites is thought to represent a heterogeneous group of mild inborn errors of energy metabolism which may be compatible with survival at least into young adulthood, but not with normal development of mental and neurological functions.

Adult↗
PubMed1986

Dermatoglyphic peculiarities in families with X-linked mental retardation and fragile site Xq27: a collaborative study.

The dermatoglyphic patterns of fingertips, palms and soles of 75 male patients with X-linked mental retardation and fra-Xq27 and of 28 obligate female heterozygotes were analyzed and compared with the data from 200 male and 200 female control individuals. The results show that there is a strong association between the fra-X-syndrome and dermatoglyphic peculiarities observed in male patients and also in female heterozygotes. The characteristic dermatoglyphic features of the fra-X-syndrome are: increased frequencies of radial loops, whorls and arches on the fingertips, a pronounced transversal course of palmar ridges, lower a-b RC, absence of c-triradii on the palms, abnormal palmar and plantar creases, dysplasia of the papillary ridges and low frequencies of true patterns on the soles. Some of these patterns were found in the female carriers of fra-Xq27 also. The combination of palmar and plantar patterns, expressed by a "log. score-Index", provides a high degree of discrimination between the male patients with fra-X-syndrome and the control group. A preliminary log. score-Index was developed also for the female heterozygotes. A "phantom picture" of the dermatoglyphic stigmata is constructed. We suggest that dermatoglyphic examination of the members of families suspected for fra-Xq27-syndrome can be useful for predicting this state and for diagnosing male hemizygotes and carrier females.

Adolescent↗
PubMed1985

Familial microtia, meatal atresia, and conductive deafness in three siblings.

We report on three sibs with right-sided microtia, meatal atresia, and conductive deafness. Two of the sibs also had right-sided palatoplegia. These sibs may have the autosomal-recessive form of microtia (No. 25180, McKusick [1983]), of which few familial cases are known to date. The malformation is due to a disturbance of the development of the first and second branchial arches. Review of the literature shows that microtia and meatal atresia with or without middle-ear involvement are developmental field defects which, either isolated or as a part of the facio-auriculo-vertebral spectrum, may occur (1) sporadically, (2) as component manifestation of syndromes, (3) as a multifactorial, or (4) as an apparent Mendelian trait.

Abnormalities, Multiple↗
PubMed1985

Keto acids in tissues and biological fluids: O-t-butyldimethylsilyl quinoxalinols as derivatives for sensitive gas chromatographic/mass spectrometric determination.

Quinoxalinol t-butyldimethylsilyl ethers were prepared from three branched-chain and from two aliphatic unbranched 2-keto acids. The electron impact (EI) mass spectra display pronounced [M-57]+ ions. With 39-51% of total ion current contained within them, sensitivity is greater than on chemical ionization (CI) mass spectrometry of O-trimethylsilyl derivatives. Mass spectra and chromatographic behaviour of these novel keto acid derivatives are discussed and preliminary quantitative data from rat muscle are given.

Animals↗
PubMed1985

A male with a monocentric Yq isochromosome and presence of a Yp-specific DNA sequence.

We describe clinical features and laboratory findings in a physically and mentally retarded male with underdeveloped testes, a seemingly monocentric isochromosome of Yq but the presence of a Yp-specific DNA sequence at a single dose of unknown genomic localisation, and the presence of H-Y antigen at normal male titer. Our data contribute to the fine mapping of the human Y chromosome by correlating phenotypic features with results from karyotypic, immunologic, and molecular hybridisation analyses.

Adolescent↗
PubMed1985

Serum branched chain amino and keto acid response to fasting in humans.

Eight healthy individuals were fasted for 72 hours. The concentrations of the branched chain keto acids (BCKA), branched chain amino acids (BCAA), C peptide, and glucagon were determined in peripheral venous blood. alpha-ketoisocaproic acid, alpha-keto-beta-methyl-n-valeric acid, and alpha-ketoisovaleric acid increased significantly within 36 hours along with the corresponding amino acids. After 60 hours of starvation, the concentrations of BCKA and BCAA declined despite the fact that the subjects were still in the fasting state. These changes were accompanied by a decrease in the concentrations of C peptide and an increase in glucagon levels. It is suggested that in starving man insulinopenia may contribute to the rise in BCKA concentrations and that the increase in BCKA may be a mechanism to reduce proteolysis.

3-Hydroxybutyric Acid↗
PubMed1984

Developmental pathogenesis of chromosome disorders: report on two newly recognized signs of Down syndrome.

Testing the hypothesis of amplified developmental instability in autosomal trisomies as proposed by Shapiro we predicted and found an increased frequency of symphalangies in the toes of patients with Down syndrome. In our X-ray study of the feet of 71 adults with trisomy 21 we also detected a greater than normal number of sesamoid bones. A corollary to Shapiro's hypothesis is a dependence on ethnic origin of the frequency of symptoms in Down syndrome. Compared to data from Europe, toe symphalangies are more prevalent in Japan. We predict this anomaly to occur even more often in Japanese patients with trisomy 21.

Adult↗
PubMed1984

Mean corpuscular hemoglobin is increased in Martin-Bell syndrome.

Studying the blood picture of 11 patients with Martin-Bell syndrome, we found the erythrocytes relatively hyperchromic when compared to the data from 171 matched controls living in the same institution. Because mean corpuscular hemoglobin is increased also in patients with folic acid deficiency states, we feel that our data provide further evidence that Martin-Bell syndrome is an inherited disease of folate metabolism.

Adult↗
PubMed1984

Restriction fragment length polymorphisms at the human parathyroid hormone gene locus.

Two common Pst I and Taq I restriction enzyme fragment length polymorphisms (RFLPs) were detected at the human parathyroid hormone (PTH) gene locus. The allele frequencies in a Northern German population were 0.578/0.422 (Pst I) and 0.628/0.372 (Taq I). The allele distributions follow Hardy-Weinberg expectations of equilibrium in the population. The Mendelian nature of the polymorphisms were confirmed in family studies.

Alleles↗
PubMed1984

Mitochondrial myopathy with lactic acidosis and deficient activity of muscle succinate cytochrome-c-oxidoreductase.

A male infant had severe muscular hypotonia from birth. Recurrent vomiting with dehydration and severe metabolic acidosis complicated the course. Elevated lactate (up to 12.3 mmol/l; n less than 2), pyruvate (0.4 mmol/l; n less than 0.05) and alanine levels were found in serum with an abnormal lactate/pyruvate ratio (greater than 30; n less than 15). In urine the concentrations of lactate, pyruvate, alanine and of several intermediates of the citric acid cycle were increased. In muscle, numerous disseminated "ragged red fibres" were found by light microscopy; muscle fibres were found to contain subsarcolemmal aggregates of mitochondria, lipid droplets and glycogen by electromicroscopical methods. Moreover, mitochondria with a typical circular arrangement of cristae were noticed. In liver homogenates normal activities of pyruvate carboxylase and pyruvate dehydrogenase complex were found; in liver mitochondria also succinate-cytochrome-c-oxidoreductase activity was normal. However, in muscle no succinate-cytochrome-c-oxidoreductase activity was detectable. The patient became increasingly lethargic and died because of sepsis at 5 months of age.

Acidosis↗
PubMed1984

Hereditary ocular dysproteinhydria of the aqueous humour with crystalline deposits.

We describe a family with coloured crystalline deposits on the corneal endothelium and on the lens surface. A protein with a molecular weight of about 110,000 and an isoelectric point of 7-8 could be demonstrated in the aqueous humour, which was not found in the controls or in the serum of the family members. The pedigree is suggestive of autosomal dominant inheritance. To our knowledge this is the first report of this entity.

Adult↗