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T Horii

Publications and source records attributed to T Horii.

166 records · Page 10Linked to original sources
PubMedDate not supplied

Head to head dimer model; an alternative model for the strand exchange reaction by RecA protein of Escherichia coli.

The RecA protein of E coli promotes a strand exchange reaction in vitro which appears to be similar to homologous genetic recombination in vivo. A model for the mechanism of strand transfer reaction by RecA protein has been proposed by Howard-Flanders et al based on the assumption that the RecA monomer has two distinctive DNA binding sites both of which can bind to ssDNA as well as dsDNA. Here, I propose an alternative model based on the assumption that RecA monomer has a single domain for binding to a polynucleotide chain with a unique polarity. In addition, the model is based on a few mechanical assumptions that, in the presence of ATP, two RecA molecules form a head to head dimer as the basic binding unit to DNA, and that the binding of RecA protein to a polynucleotide chain induces a structural change of RecA protein that causes a higher state of affinity for another RecA molecule that is expressed as cooperativy. The model explains many of the biochemical capabilities of RecA protein including the polar polymerization of RecA protein on single stranded DNA and polar strand transfer of DNA by the protein as well as the formation of a joint DNA molecule in a paranemic configuration. The model also presents the energetics in the strand transfer reaction.

Adenosine Triphosphate↗
PubMedDate not supplied

The Batista operation in patients with dilated cardiomyopathy.

Between December 1996 and October 1998, 34 patients with nonischemic dilated cardiomyopathy (DCM) received cardiac volume reduction surgery. The patients' ages ranged from 14 to 67 years (mean = 48 years) and included 28 males and 6 females. Associated mitral regurgitation was present in 31 patients, tricuspid regurgitation in 19 patients, and aortic regurgitation in 4 patients. We performed a partial left ventriculectomy (PLV) using antegrade intermittent warm blood cardioplegia in 15 patients (group A), and in 19 patients (group B) PLV was performed using the on-pump beating heart technique. In group A, the mean aortic clamping time was 79+/-33 minutes and the total cardiopulmonary bypass time was 155+/-58 minutes. In group B the mean cardiopulmonary bypass time was 121+/-43 minutes. There were eight hospital deaths (five in group A and three in group B). Five of 10 survivors of group A required inotropic support for 13.8+/-25.3 days after the operation, while 5 of 12 survivors in group B required inotropes for 4.2+/-3.1 days. Hospital mortality was 86% in 7 emergent cases and 7% in 27 elective cases. Echocardiographic study showed that the left ventricular ejection fraction improved from a mean of 18.7% to 30.3% and the left ventricular diameter decreased from a mean of 80.2 mm to 62.3 mm after the operation. All 26 hospital survivors were followed for 1 to 20 months. Three patients died at early follow-up because of congestive heart failure, thrombosed valve, and hepatic failure, respectively. Nineteen patients were in New York Heart Association (NYHA) Class I or II and four were in NYHA Class III. In conclusion, cardiac volume reduction surgery is effective when the operative technique and proper judgment of patient selection are established, and emergent operation is avoided.

Adolescent↗