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Biomedical subjects

R Koch

Publications and source records attributed to R Koch.

At least 325 records · Page 18Linked to original sources
PubMed1979

[Determining the overall density of permanent human teeth and its relation to the carrier's age (author's transl)].

(1) The pyknometer method was used to determine the specific gravity of the roots, central portions (necks), and crowns of 130 human teeth (incisors, canines, premolars, molars) obtained during autopsies. The overall density or specific gravity was calculated as the mean of the values obtained for these portions of permanent teeth. To test the relation between the total specific gravity and the carrier's individual age, a simple linear regression was calculated. It was not possible for a definite relation to be found between the specific gravities of teeth and the age of their carriers. (2) Limits to determining the individual age from the specific gravity of teeth are set especially by the factors discussed in this paper, by pathological influences, and by variations of specific gravity within isolated hard dental tissue. In human teeth, age-dependent physiosclerosis of bradytrophic tissue obviously is in the form of re- or transmineralization without major changes in the degree of mineralization and is usually overlapped by other phenomena. In addition, preparative and technical faults may result in false specific gravities being obtained. (3) Specific gravities of portions of teeth and total specific gravities determined therefrom cannot be used to find the carrier's age and, therefore, should be dismissed as means of identifying age by methods of forensic stomatology.

Adult↗
PubMed1978

Biochemical studies of a human low-activity galactose-1-phosphate uridyl transferase variant.

A low activity galactose-1-phosphate uridyl transferase (transferase) variant in a newborn infant has been demonstrated by biochemical studies in erythrocytes and cultured skin fibroblasts. The newborn infant was a galactosaemic suspect identified in a neonatal metabolic screening programme. On breast feeding, he did well without clinical symptoms of galactosaemia during the first 15 days of life. However, substantial amounts of erythrocyte galactose-1-phosphate and urinary galactitol corresponding to the levels in untreated galactosaemic patients, along with mild amino aciduria, were found. The transferase activity, as measured by a sensitive micro kinetic radioisotopic method, was about 7--10% of the normal. On starch gel electrophoresis, the enzyme from the haemolysate had similar mobility as the normal in Tris--glycine buffer, pH 8.8 and phosphate buffer, pH 7.0, but had a slower mobility than that of the normal in the histidine buffer, pH 7.8. The mobility difference was much clearer in a semipurified enzyme preparation. The transferase enzyme in the haemolysate appeared to be more heat labile.

Cells, Cultured↗
PubMed1978

Diet, genetics, and mental retardation interaction between phenylketonuric heterozygous mother and fetus to produce nonspecific diminution of IQ: evidence in support of the justification hypothesis.

The justification hypothesis postulates that an individual genetically deficient in the synthesis of any of the 12 nonessential amino acids requires that amino acid in the diet just as a normal individual requires any essential amino acid. The deficiency of that single amino acid causes diminished protein synthesis. The hypothesis proposes that mental retardation develops during the late stage of fetal development, when the brain is growing most rapidly, as a result of the inability of the mother to deliver an appropriate amount of that nonessential amino acid to her fetus who, in turn, is unable to correct for this deficiency due to his genetic constitution. A paradigm is provided by the disease phenylketonuria in which the homozygote lacks the enzyme for synthesis of the nonessential amino acid tyrosine. By measuring the appearance of tyrosine in the plasma after an oral dose of phenylalanine, it is possible to show differential capability among siblings of known phenylketonuric children, in the expected Mendelian ratio. The mean IQ of the two-thirds of the siblings who were least able to convert phenylalanine to tyrosine (presumably heterozygotes) was 10 points lower than the mean IQ of the "normals," who were most able to synthesize tyrosine. The difference is statistically significant (P <0.01). The mean maternal IQ was halfway between that of the heterozygote group and that of the normal group, confirming the prediction of maternal-fetal interaction.

Diet↗
PubMed1978

Congenital and neurological abnormalities in infants with phenylketonuria.

We reported the occurrence of congenital and neurological abnormalities in 150 children with phenylketonuria (PKU) age 1 year or older, who have been treated with a restricted phenylalanine diet, according to the protocol used in a nation-wide longitudinal collaborative study of children treated for PKU. The overall occurrence (9.3%) of congenital anomalies was not significantly different from that of a general population, except for an apparent increased incidence of pyloric stenosis. None of the subjects had a persistent major neurological defect.

Abnormalities, Multiple↗
PubMed1977

Representation of the cochlea in the neocortex of guinea pigs.

By recording unit clusters and local evoked responses in the auditory cortex of guinea pigs the cortical representation of best frequencies was studied. In penetrations vertical to the cortical surface best frequencies were similar. Parallel to the cortical surface, however, different frequencies were found in the antero-posterior direction, whereas medio-laterally best frequencies usually remained in the same range (isofrequency stripes). Two auditory cortical fields could be distinguished, which are tonotopically organized. With increasing sound intensity the cortical response field for a given frequency and thus the frequency overlap increased. All along the isofrequency stripes in the medio-lateral direction, the stimulation of the contralateral ear produces larger responses than the same stimulus delivered to the ipsilateral ear.

Acoustic Stimulation↗
PubMed1977

The isolation of tubulin and actin from mouse 3T3 cells transformed by simian virus 40 (SV3T3 cells), an established cell line growing in culture.

Tubulin can be purified from mouse SV3T3 cells (3T3 cells transformed by SV40 virus) by several cycles of temperature-dependent polymerization and depolymerization. Electron microscopical analysis of the final product reveals morphologically normal microtubules. Homogeneous actin can be isolated as a byproduct of the purification procedure. Mouse SV3T3 actin and skeletal muscle actin were compared by fingerprint analysis of the tryptic peptides obtained from performic-acid-oxidized protein. The two actins show a high degree of homology although apparently five of the twenty-five spots visualized by fluorescamine show a difference in chromatographic mobility. The purification procedure described allows the rapid isolation of both actin and tubulin from tissue culture in sufficient amounts for comparative biochemicals studies.

Actins↗
PubMed1977

Collaborative study of children treated for phenylketonuria: study design.

Studies that have attempted to test the effectiveness of treatment in phenylketonuria (PKU) have been handicapped by small samples due to rarity of the disorder and inadequate control of other sources of error. The present study was designed to overcome these limitations by treating a large number of children with PKU under controlled conditions from near birth to 6 years of age. Nineteen medical centers in 13 states have participated in the study, which is currently in progress. This article is one of a series of final reports. It describes the study design and sampling procedures employed to answer questions of interest for which results will be reported in subsequent articles. The study serves as a model for future collaborative investigations of a similar nature.

Child↗