Search PubMed⌕ Search

Biomedical subjects

P Hirsch

Publications and source records attributed to P Hirsch.

At least 91 records · Page 5Linked to original sources
PubMed1972

Deoxyribonucleic acid base sequence homologies of some budding and prosthecate bacteria.

The genetic relatedness of a number of budding and prosthecate bacteria was determined by deoxyribonucleic acid (DNA) homology experiments of the direct binding type. Strains of Hyphomicrobium sp. isolated from aquatic habitats were found to have relatedness values ranging from 9 to 70% with strain "EA-617," a subculture of the Hyphomicrobium isolated by Mevius from river water. Strains obtained from soil enrichments had lower values with EA-617, ranging from 3 to 5%. Very little or no homology was detected between the amino acid-utilizing strain Hyphomicrobium neptunium and other Hyphomicrobium strains, although significant homology was observed with the two Hyphomonas strains examined. No homology could be detected between prosthecate bacteria of the genera Rhodomicrobium, Prosthecomicrobium, Ancalomicrobium, or Caulobacter, and Hyphomicrobium strain EA-617 or H. neptunium LE-670. The grouping of Hyphomicrobium strains by their relatedness values agrees well with a grouping according to the base composition of their DNA species. It is concluded that bacteria possessing cellular extensions represent a widely diverse group of organisms.

Adenine↗
PubMed1968

Cell wall composition of Hypomicrobium species.

Chemical analysis of cell walls obtained from Hyphomicrobium B-522 and from a morphologically and nutritionally distinct organism, Hyphomicrobium neptunium (ATCC 15444), showed that the organisms have a similar cell wall composition, which is typical of gram-negative bacteria. The walls of both strains contained many amino acids, including the characteristic mucopeptide components diaminopimelic acid and muramic acid. Isolation of the mucopeptide by use of sodium dodecyl sulfate was successful only with cell walls of H. neptunium, thus revealing a difference between the walls of the two strains. The mucopeptide preparation contained glucosamine, muramic acid, alanine, glutamic acid, diaminopimelic acid, and glycine in molar ratios of 1.05:1.21:1.84:1.0:1.04:0.31, respectively. The concentration of glycine was sufficiently high to suggest that it is a mucopeptide component rather than an impurity.

Amino Acids↗
PubMedDate not supplied

Hepatitis TT virus infection in high-risk groups.

The novel hepatitis TT virus first described by a Japanese group has been reported to be parenterally transmitted and furthermore, to have been detected in patients with hepatitis of unknown etiology. Hence, in the present study its prevalence was investigated within groups at high risk for contracting blood-borne viruses, such as individuals with chronic liver disease, intravenous drug users and recipients of blood and blood products, as compared to voluntary blood donors and pregnant women. To that end, DNA was extracted from sera obtained from the respective patients and subjected to PCR using semi-nested primers. The frequency of TTV DNA detected within high risk groups, such as nine out of 50 patients with chronic non-A-to-G liver disease (18%), nine out of 98 hepatocellular carcinoma cases (9.2%), 17 out of 52 intravenous drug users (32.7%), 15 out of 80 thalassemia patients with multiple blood transfusions (18.8%) and three out of 31 prostitutes (9.7%) exceeded that among voluntary blood donors and pregnant women, which amounted to 14 out of 200 (7%) and seven out of 103 (6.8%), respectively. Additional molecular research should be performed in order to determine its short-, as well as long-term clinical significance.

Adolescent↗