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Biomedical subjects

R Hausmann

Publications and source records attributed to R Hausmann.

76 records · Page 5Linked to original sources
PubMed1966

Methylation of DNA.

The methylated bases of DNA are formed by the transfer of the methyl group from S-adenosylmethionine to a polynucleotide acceptor. This transfer is catalyzed by highly specific enzymes which recognize a limited number of available sites in the DNA. The mechanism for the recognition is presently unknown. In some instances, there is evidence that other cellular components, such as lipopolysaccharides, can influence the methylation reaction. Certain bacteriophages induce new methylases upon infection of their hosts. Phage T3 is unique in establishing an environment in which methylation of neither the phage nor the host nucleic acid can occur. By superinfecting T3-infected cells with other phages, the latter can be obtained with methyl-deficient DNA. Although a great deal is known about the enzymology of the methylation reaction, and there appears to be a strong correlation between the in vitro and in vivo reactions, studies in which DNA is either supermethylated or totally unmethylated have not yielded any insight as to what the possible function of the methylated bases may be.

Alkylation↗
PubMedDate not supplied

Phase-contrast MR angiography with reduced acquisition time: new concepts in sequence design.

A new acquisition scheme for three-dimensional (3D) phase-contrast MR angiography reduces by 33% the measurement time for a data set sensitive to flow in all three orthogonal directions. Background suppression is achieved by acquiring a flow-compensated data set and three data sets flow encoded in the three orthogonal directions, with subsequent complex subtraction. The data are acquired in an interleaved fashion, eliminating misregistration artifacts due to patient motion between measurements sensitive to different flow directions. A standard maximum-intensity-projection algorithm is applied to the combined 3D data set to obtain angiographic projections sensitive to all three orthogonal flow directions. The theory and implementation of the method are described and examples of its application to the intracranial and abdominal circulation are provided.

Blood Vessels↗