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Biomedical subjects

Y Hirota

Publications and source records attributed to Y Hirota.

At least 487 records · Page 27Linked to original sources
PubMed1981

Inhibitory effect of adenosine 3',5'-phosphate on cell division of Escherichia coli K-12 mutant derivatives.

Cell division of Escherichia coli K-12 strain PA3092 was inhibited by the addition of adenosine 3',5'-phosphate (cAMP), and the cellular morphology was changed from rods into filaments. Nucleoids in the filaments were regularly distributed and septum formation was perfectly inhibited. This inhibition of cell division by cAMP was reversed by the addition of guanosine 3',5'-monophosphate. To examine whether the inhibitory effect of cAMP on cell division in E. coli PA3092 was specific, its effect in several parental strains was investigated. Induction of cell filamentation by cAMP was observed in E. coli PA309 and P678, but not in E. coli W505, W1, Y10, or the wild-type strain. This result suggests that filamentation by cAMP in E. coli PA3092, PA309, and P678 was due to the mutagenesis by which E. coli P678 was derived from E. coli W595.

Cell Division↗
PubMed1981

[Pathophysiology of hypertrophic and congestive cardiomyopathies: a guide of fundamental therapeutic approach (author's transl)].

A precise assessment of left ventricular (LV) function was performed in 20 patients with hypertrophic cardiomyopathy (HCM) and 14 patients with congestive cardiomyopathy (CCM) to elucidate the pathophysiology of these diseases, expecting to establish a fundamental therapeutic approach of them. Twenty-two patients who underwent cardiac catheterization and were found to have normal LV function served as normal control. LV preload, defined as LV end-diastolic stress, was normal in HCM, and it was elevated in patients with CCM and congestive heart failure (CHF). While an index of afterload, defined as mid-systolic stress, was markedly reduced in HCM, it was elevated in CCM and CHF. Although three indices of LV contractility including the rate of LV pressure rise divided by developed pressure of 40 mmHg ((dp/dt)/DP40), ejection fraction (EF) and LV minute work index, were all in a normal range in HCM, they were very low in CCM. This observation indicates that the systolic function of HCM is normal as a pump, and that it is markedly reduced in CCM. One index of LV relaxation, which was the peak rate of LV pressure fall (peak negative dp/dt) was reduced in both HCM and CCM, and the other index, which was the time constant of LV pressure fall (the time constant T) was prolonged in both of these diseases. An index of compliance, defined as diastolic elastic stiffness constant (K) was high in HCM and normal in CCM, and the other index, defined as end-diastolic elastic stiffness was normal in HCM and high in patients with CCM and CHF. This observation suggests that chamber compliance is low in HCM, and that muscle compliance begins to decline with the appearance of CHF in CCM. Although poor systolic function is evident in CCM, poor contractility or inadequate contraction of a unit muscle is also suspected in HCM since 1) normal EF was maintained with very low afterload, 2) LV end-systolic volume index was normal with very low end-systolic stress, and 3) LV unit muscle minute work about one half of normal value with normal preload. Several important therapeutic guidelines can be derived from this study: As CCM is a disease of reduced LV contractility, the main therapy for this disease is to enhance the contractility. Elevation of preload and afterload are associated with the appearance of CHF, and this coincides with New York Heart Association functional class III. Therefore, the indication of preload and/or afterload reducing agents, such as diuretics and vasodilators, is considered for such patients. Although preload and/or afterload reducing agents are well known to be contraindicated in obstructive type of HCM, since they increase the intracardiac pressure gradient, these agents must be used with great precaution in nonobstructive type, as they reduce preload suddenly, and life-threatening low cardiac output might take place. For the same reason, strenuous exercise must be prohibited in HCM...

Adolescent↗
PubMed1981

Phase I--II study of N4-behenoyl-1-beta-D-arabinofuranosylcytosine.

A phase I-II study of N4-behenoyl-1-beta-D-arabinofuranosyl-cytosine (BH-AC) was conducted by a cooperative study group. In phase I study, a total of 126 patients, 64 of whom had metastatic solid tumors and 62 of whom had leukemia, were administered BH-AC in a single IV dose at day 1 only or in daily IV doses for 3 to 21 days, with dose ranges of 1.5--10.0 mg/kg. Side effects included nausea and vomiting, which were significantly less in incidence and severity than those observed with ara-C. Myelosuppressive toxicity became severe with doses 3.6--5.0 mg/kg per day x 10 days. In phase II study, a total of 37 adult patients with acute leukemia were entered in the study. Responses were noted, with an overall rate of 35% complete remission. Of th 26 patients with AML, there were 13 CR. The recommended schedule of treatment for BH-AC, based on our data, is daily infusion of 4--5 mg/kg over 3 h for approximately 3 weeks. The results with BH-AC in patients with acute leukemia are superior to those which have been reported for ara-C.

Adolescent↗
PubMed1980

Terminal deoxynucleotidyl transferase in the blastic phase of chronic myelogenous leukemia: an indicator of response to vincristine and prednisone therapy.

Terminal deoxynucleotidyl transferase (TdT) activity was assayed in leukemic cells of 34 patients in blastic phase of Philadelphia-positive chronic myelogenous leukemia (CML). The TdT levels were correlated with the response to vincristine and prednisone therapy. None of 20 Tdt-negative patients, but 10 of 14 TdT-positive patients responded to vincristine and prednisone. There was poor correlation between blast cell morphology and response to this therapy. This study confirms that TdT levels in the majority of patients predict effectiveness of vincristine and prednisone therapy in blastic phase of CML.

Adolescent↗
PubMed1980

Replication origin of the Escherichia coli K-12 chromosome: the size and structure of the minimum DNA segment carrying the information for autonomous replication.

A DNA fragment containing the replication origin of the Eschericia coli K-12 chromosome was inserted in two correlations at either the BamHI or SalI site of pBR322 DNA. All the resulting hybrid plasmids were found to replicate in both polA and polA+ cells, whereas pBR322 replicates only in polA+ cells. This characteristic provided a method for assaying the autonomously replicating ability (Ori function of the E. coli origin. In order to define the minimum DNA region (ori) that determines Ori function, deletions of various sizes were introduced from either side of the ori-containing segment in the hybrid plasmids by in vitro techniques, and the correlation between the Ori phenotype and nucleotide sequence of the deletion derivatives was analyzed. It was found that the left end of ori is between positions 23 and 35, and the right end is either position 266 or 267 in our nucleotide coordinate (Sugimoto et al., 1979). Therefore, ori is present within a region of minimum 232 base pairs and maximum 245 base pairs in length. The Ori+ and Ori- phenotypes were clearly resolved at both sides of these boundaries by the above assay procedure. To obtain information about the effect of mutations in the internal region of the defined ori stretch, short sequences were inserted or deleted in vitro in the vicinity of several restriction sites within ori on the hybrid plasmids. Most of these plasmids carrying modified sequences showed Ori- phenotype, suggesting that most parts of the ori stretch play important roles in Ori function.

Base Sequence↗
PubMed1980

Clinicopathological study of the heart and coronary arteries of autopsied cases from the community of Hisayama during a 10-year period. Part IV. QS waves in the precordial leads.

During a ten-year period, from November 1, 1961, to October 31, 1971, 339 residents aged 40 years or over at death were nonselectively autopsied in a Japanese community, Hisayama town (mean autopsy rate: 84%). One or more standard 12-lead ECGs plus V4R and V7 electrocardiograms taken at periodic medical examinations were available for 308 of them. In 46 persons, QS waves were localized in one or more leads from V1 to V4. By transverse sectioning of the hearts, old myocardial infarction extending into the interventricular septum was found in nine of these 46 persons. Frequency of myocardial infarction cases in each category for QS localization was as follows: Lead V1 to V4, three of three; Leads V1 to V3, six of nine; Leads V1 and V2, three of 15; Leads V2 and V3, none of two; Lead V3, none of one; Lead V2, one of eight; and Lead V1, one of 25.

Adult↗
PubMed1980

Cerebral and aortic atherosclerosis in Hisayama, Japan.

This study of autopsy cases in the general population of the town, Hisayama, describes the incidence and severity of aortic and cerebral atherosclerosis in Japan. Atherosclerosis was more severe in the aorta than in the cerebral arteries of all age groups and its disparity became more conspicuous with age. In hypertensive cases, atherosclerosis was more severe in both the aorta and the cerebral arteries from and beyond the 6th decade of age. The severity of atherosclerosis in the aorta in those with systolic hypertension was lower under the age of 79 and higher after the age of 80 than in diastolic hypertension; the cerebral arteries were afflicted similarly by the two forms of hypertension. The serum cholesterol level correlated better with the severity of aortic than cerebral atherosclerosis.

Adult↗