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Biomedical subjects

P Tchen

Publications and source records attributed to P Tchen.

24 records · Page 2Linked to original sources
PubMed1974

Extent of transcription of mouse sarcoma-leukemia virus by RNA-directed DNA polymerase.

The DNA product obtained from the endogenous RNA-directed DNA polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) reaction of the Moloney sarcoma:leukemia viruses produced by the 78 A-1 cell line was analyzed and characterized. The extent of transcription of viral 70S RNA was measured by RNA.DNA hybridization ((32)P-viral RNA-(3)H product DNA). No double-stranded DNA was obtained. The product consisted of 95-99% single-stranded DNA with an average length of 200 nucleotides. In contrast to the results reported with avian and other RNA oncogenic viruses, it was found that the entire 70S viral RNA genome was transcribed into DNA pieces and that a small excess of the product DNA was sufficient to anneal the 70S RNA and render it totally resistant to single-stranded-specific enzyme digestion.

Animals↗
PubMedDate not supplied

Non-radioactive oligonucleotide probe for detection of clinical enterotoxigenic Escherichia coli isolates of bovine origin.

Oligonucleotides (32 or 34 mer) corresponding to enterotoxigenic Escherichia coli STIa (ST-P) toxin gene were tailed with Bio-11-dUTP using terminal deoxynucleotidyl transferase. Plasmids from clinical E. coli isolates were prepared by modified rapid alkaline lysis procedure and dot-spotted. Biotinylated oligonucleotide probes were hybridized to detect the STIa toxin gene. The results were in agreement with that obtained by radioactive oligonucleotide probes. Of 135 clinical isolates (sampled from 6 different regions of France), only 7 (5.2%) were found to be STIa+. These 7 isolates were the only ones to be found positive for the K99 adhesive pili antigen. Both the probes were specific to the STIa toxin gene and failed to detect the closely related STIb (ST-H) toxin gene. Possibilities of their wide usage in clinical labs are discussed.

Animals↗
PubMedDate not supplied

Genetic study of the Cuiva Indians of Venezuela.

Serum and red cell protein markers were investigated in Cuiva Indians. Our ethnologic studies indicate that the low degree of genetic variability in this population is probably due to genetic drift.

Asian People↗