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Biomedical subjects

A Knapp

Publications and source records attributed to A Knapp.

At least 55 records · Page 3Linked to original sources
PubMed1983

[Detection of phenylalanine hydroxylase activity in leukocytes and fibroblasts].

Phenylalanine hydroxylase activity measured in leucocytes and fibroblasts by the fluorometric method is nonspecific and can be released by other aromatic hydroxylases. Investigations with the inhibitors p-Cl-phenylalanine, 3-I-tyrosine and 6-F-tryptophan made evident that these results may be caused by the tryptophan hydroxylase and the tyrosine hydroxylase. Phenylalanine hydroxylase activities in leucocytes could also not be measured by radiochemical investigations with [3-14C] phenylalanine (scanner and liquid scintillation technique).

Fibroblasts↗
PubMed1982

The genetic linkage between the PKU locus and the loci for amylase 1, amylase 2, Fy, PGM 1, and Rh and the question of assignment of the PKU locus to chromosome no. 1.

The alpha-amylase loci Amy 1 and Amy 2 and other loci on chromosome 1 were investigated for their linkage relationship to the PKU locus. Ten families were informative for the study of linkage between PKU/Amy, 20 for PKU-Fy, 11 for PKU/PGM 1, and 10 for PKU/Rh linkage. The probabilities of linkage at different recombinant fractions were calculated according to Bayes' theorem. The results are in striking contrast with those of Kamaryt et al. who found strong evidence for close linkage between the amylase loci and the PKU locus, whereas with our results close linkage can be excluded; loose linkage is possible but unlikely. The results are discussed with regard to the genetic heterogeneity of phenylketonuria.

Amylases↗
PubMed1982

[Neuropathological findings in Lesch-Nyhan syndrome (author's transl)].

The Lesch-Nyhan syndrome is commonly regarded as a metabolic disorder of the purine metabolism without specific morphological changes. In the present paper a report is given on a 13-year-old boy. The neuropathological investigation revealed PAS positive deposits in the ganglion cells of the nucleus olivaris. In HE preparations, the storage material appears as light foamy accumulations displacing nuclei to the cell border. The deposits are sudan-III-negative and there is no UV fluorescence. Electron microscopically the primarily formol fixed tissue of the nucleus olivaris shows circumscribed accumulations of a relatively homogeneous substance with medium density in the dilated smooth endoplasmic reticulum. The diameter ranges from 476 to 850 nm. In this connection, it seems to be possible that the lack of cGMP might lead to disturbances of the protein metabolism of postsynaptic structures, the significance of which is discussed. It is suggested that further investigations of the CNS in Lesch-Nyhan patients should be focussed on the nucleus olivaris.

Adolescent↗
PubMed1981

[Porphyrin diseases with particular emphasis on hereditary].

During the last 10 years our knowledge concerning the basis defect in porphyrias has increased so that a better genetic family advice. The following basis defects were found: 1. Uroporphyrinogen-III-cosynthetase in porphyria erythropoetica congenita, 2. haem-synthetase in protoporphyria erythropoetica, 3. uroporphyrinogen-1-synthetase in porphyria acuta intermittens, 4. uroporphyrinogen-carboxylase in porphyria cutanea tarda. According to this in porphyria cutanea tarda a genetic defect is supposed, which leads to the disease in connection with the environmental factors. On the basis of the biochemical findings a better understanding of the heredity is possible which is discussed in detail.

Adult↗
PubMed1978

[Tryptophan metabolism and oligophrenia (author's transl)].

After dealing with the biochemistry of tryptophan metabolism the most important results obtained in humans are presented. Special emphasis is given to the hereditary defects of tryptophan metabolism associated with mental retardation and convulsions due to lack of pyridoxine. The author's findings demonstrate the existence of a hereditary disturbance of the tryptophan metabolism via kynurenine in a certain part of oligophrenic patients. This metabolic defect can be controlled by high doses of vitamin B6. Furthermore investigations conducted with a view to interpreting these results are discussed, especially the determination of kynureninase activity, serotonin blood levels and pyridine nucleotide synthesis.

Amino Acid Metabolism, Inborn Errors↗