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Biomedical subjects

H Feldmann

Publications and source records attributed to H Feldmann.

At least 217 records · Page 12Linked to original sources
PubMed1975

tRNAs undermethylation in a met-regulatory mutant of Saccharomyces cerevisiae.

A study of in vivo and in vitro methylation of tRNAs in regulatory mutants affected in methionine-mediated repression (eth2, eth3, eth10) has led to the following results: 1) The eth2-2 carrying strain presents a great undermethylation of its tRNAs of the same order of magnitude as observed during methionine starvation of methionine auxotrophs. 2) This undermethylation leads to a shift of the tRNAIII met peak on a BD cellulose column, while tRNAIII met peak is unchanged. 3) The study of a double mutant strain carrying eth2 and met2 mutations has shown that this undermethylation is a consequence of the high internal pool of methionine. 4) Undermethylation unequally affects the different bases and the different tRNA species.

Carbon Radioisotopes↗
PubMed1975

Characteristics of DNA fractionated on benzoylated DEAE-cellulose.

Chromatography on BD-cellulose columns with a salt gradient and formamide separates cellular DNA into two fractions (fraction I eluted within the salt gradient, fraction II with formamide), the proportions of these two fractions (ca. 2:1) being similar for DNA from a number of eucaryotic organisms. Yeast DNA was chosen for a detailed study of the mode of fractionation. Several physicochemical parameters, binding to nitrocellulose filters, sensitivity towards nuclease S1, labelling properties in vivo, and hybridization properties of the two DNA fractions were compared. It was shown that both fractions are native DNA and that the fractionation does not depend on the size or the (G + C) content of the DNA. Fraction I DNA contains only a small portion of molecules having single-stranded ends. Fraction II DNA is a heterogeneous population, containing molecules with peculiar structural characteristics: (a) It contains DNA molecules with single-stranded ends and/or gaps sensitive to nuclease S1; labeling experiments suggested that these are molecules undergoing repair and replication. (b) Another portion of fraction II is molecules sensitive to nuclease S1 in regions which are not single-stranded. (c) A third portion is DNA which, after treatment with nuclease S1, is still strongly bound to the resin. Indications that the segregation may be due to the presence of specific DNA sequences comes from the above experiments and from the finding that fraction I DNA is enriched in ribosomal genes and fraction II DNA in tRNA genes.

Centrifugation, Density Gradient↗
PubMed1975

Purification of tDNA from yeast.

tRNA-tDNA hybrids from yeast have been isolated. The main step in purification was chromatography on a BD-cellulose column with salt gradients and formamide, which separates the hybrid material from excess DNA. The hybrids were characterized by density centrifugation in CS2SO4 and by treatment with alkali and pancreatic ribonuclease. Experiments in which DNA that had been sheared to different molecular weights was used for hybrid formation suggest that the tRNA cistrons are tandemly arranged and that the external spacer DNA is preserved in the tDNA.

Centrifugation, Density Gradient↗
PubMed1975

[Osteomyelitis of the frontal bone following exeresis of the N. supraorbitalis].

The paper describes a case of osteomyelitis of the frontal bone after exeresis of the first trigeminal branch, which was postoperatively precipitated probably by chronically relapsing hordeola. General principles of skull-cap osteomyelitis are discussed, and conclusions are drawn form the case describe in the paper.

Adult↗
PubMed1975

[Communicative aspects of studies in schizophrenia].

Family studies of schizophrenics have shown the importance of factors such as a malignant mother-child symbiosis, changes in the family role structure, pseudo-mutuality and techniques on how 'to drive someone crazy'. More recent studies concern themselves with disturbance of communication and interaction within schizophrenic families. In particular, the problems of double-bind and other paradoxical modes of communication are discussed by the author. In contrast to double-bind as a sociological aetiological model which defines schizophrenia as a metacommunicative disturbance and evoked reaction of the self-system, the hypothesis is proposed of an intrapsychic double-bind which the patient is producing wihtin himself.

Family↗
PubMed1975

[Anomaly of supraganglionic portion of facial nerve (author's transl)].

In a boy of 10 with primary cholesteatoma of the right ear the following anomaly of the facial nerve was demonstrated: The nerve enters the mastoid posteriorly to the labyrinth, in Trautmann's area, there it makes a right-angled turn forward and runs in a horizontal, slightly upward direction through mastoid and antrum, crossing the lateral canal, via the epitympanum in close relation to body of incus and head of malleus, in which it had moulded a groove. It leaves the epitympanum superiorly to the processus cochleariformis, and joins the geniculate ganglion; from there completely normal course in tympanic and mastoid portion of Fallopian canal. The nerve could be preserved. Its identity was confirmed by electric stimulation. There were no other anomalies. The embryologic, forensic and surgical aspects of this anomaly are discussed. Reference is made to the paper of Prentiss and Dean 1905, the only known observation that resembles this case in some aspects.

Cholesteatoma↗