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Biomedical subjects

K Horiuchi

Publications and source records attributed to K Horiuchi.

At least 307 records · Page 17Linked to original sources
PubMed1976

Origin and direction of synthesis of bacteriophage fl DNA.

The origin and direction of synthesis in vivo of the viral and complementary strands of f1 DNA were studied by measuring the distribution of radioactivity along the genome after a short pulse of [3H]thymidine. The results indicate that the origins of replication of viral and complementary strands are located close to one another, probably both within a restriction fragment (HaeIII-G) which is about 120 bases long. Replication of both viral and complementary strands proceeds in the 5' leads to 3' overall direction. Thus, the viral strand is elongated in the counterclockwise and the complementary strand in the clockwise direction on the standard genetic map. A model is proposed in which only two mechanisms are invoked to generate all f1 DNA species: (1) the conversion of single-stranded viral DNA into double-stranded molecules and (2) the synthesis of viral single strands from double strands.

Chromosome Mapping↗
PubMed1976

[Sleep stages and growth hormone in manganese poisoning. Effects of L dopa].

Sleep characteristics are studied in 7 patients with sequelae of manganese intoxication and in 8 controls. A reduction in the length of the REM stage was observed, which could be prolonged by L Dopa administration, but without achieving values comparable to the controls. No changes were noted in the non-REM stage of sleep. These results are similar to the ones obtained in Parkinson's disease, suggesting clinical and probably biochemical similarities between the 2 conditions. The blood concentrations of growth hormone during sleep in the manganic patients was lower than in the control group, and no significant variations were noted after L Dopa administration.

Adult↗
PubMed1976

Technetium-99m-kethoxal-bis(thiosemicarbazone), an uncharged complex with a tetravalent 99mTc state, and its excretion into the bile.

Technetium-99m-kethoxal-bis (thiosemicarbazone) complex (99mTc-KTS), a potentially useful radiopharmaceutical for cholescintigraphy, is prepared by the reaction of KTS with 99mTcO4- in the presence of stannous chloride. Under the described conditions, a complex extractable with organic solvent was detected. Thin-layer chromatography, electrophoresis, and spectrometric analysis indicate the formation of an uncharged 99mTc(IV) complex. Organ distribution and biliary excretion studies are described. The complex showed a marked highly reproducible accumulation in the gallbladder.

Aldehydes↗
PubMed1975

Site-specific cleavage of single-stranded DNA by a Hemophilus restriction endonuclease.

Single-stranded viral DNA of bacteriophage f1 is cleaved into specific fragments by endo R-HaeIII, a restriction endonuclease isolated from Hemophilus aegyptius. The sites of the single strand cleavage correspond to those of the double strand cleavage. A single-stranded DNA fragment containing only one HaeIII site is also cleaved by this enzyme. This observation suggests that the reaction of single-stranded DNA cleavage does not require the formation of a symmetrical double-stranded structure that would result from the intramolecular base-pairing between two different HaeIII sites. Other restriction endonucleases may also cleave single-stranded DNA.

Base Sequence↗
PubMed1975

Endonuclease R-EcoRII restriction of bacteriophage f1 DNA in vitro: ordering of genes V and VII, location of an RNA promotor for gene VIII.

Replicative form DNA of bacteriophage f1 was found to be sensitive in vitro to restriction by endonuclease R-EcoRII if the DNA was isolated from an Escherichia coli strain deficient in cytosine methylase activity. A similar observation was previously made with DNA from the closely related bacteriophage fd (S. Schlagman, S. Hattman, M. S. May, and L. Berger, submitted for publication). The two DNA fragments produced by the endo R-EcoRII digestion of f1 DNA were localized on the f1 cleavage map and their genetic content was determined. The polypeptides synthesized in a "coupled" transcription-translation system under the direction of each RII fragment were examined. The results of such experiments allow the ordering of genes V and VII and indicate the location of a RNA promotor for gene VIII.

Chromosome Mapping↗
PubMed1974

Kinetics of methylation of DNA by a restriction endonuclease from Escherichia coli B.

The restriction endonuclease from E. coli B is both an endonuclease and a DNA methylase. Both activities either require or are stimulated by Mg(+2), adenosine triphosphate, and S-adenosyl-L-methionine. The particular activity which the enzyme exhibits depends upon the nature of the SB sites, the genetic sites that identify substrate DNA. Enzymatic treatment of DNA that has an unmodified, wild-type SB site results in either rapid restriction of the DNA or very slow methylation of the SB site. On the other hand, a hybrid SB site (modified), which protects the DNA molecule from restriction, results in rapid methylation of that SB site.

Adenosine Triphosphate↗