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Biomedical subjects

T Ohta

Publications and source records attributed to T Ohta.

At least 1,369 records · Page 76Linked to original sources
PubMed1979

Body surface potential distributions in posterior ventricular pre-excitation.

Waveform of the QRS complex during ventricular pre-excitation is subject to the influence of both the site of pre-excitation and the time of pre-excitation relative to that of excitation via the normal AV path. This paper reports a case in which lead V1 of the electrocardiogram (ECG) could be altered from an R to an rS pattern by the administration of atropine sulfate. The provable mechanism was that of reduced conduction time in the normal AV path with altered time phase of normal excitation and pre-excitation. This mechanism was simulated in experiments on dogs and yielded similar findings. Body surface mapping in both the patient and the dogs provided evidence that pre-excitation could be recognized by that means with varied time phase of normal excitation and pre-excitation. It was demonstrated that the QRS complex of right sided precordial leads could be altered from an R to an rS pattern by altering the time phase of normal excitation and pre-excitation of the posterior ventricular wall. This alteration was related to the degree to which negative potentials on the anterior chest wall due to right ventricular breakthrough of normal activation developed in relation to the time of pre-excitation.

Action Potentials↗
PubMed1979

Inhibitors for the mutagenicities of colon carcinogens, 1,2-dimethylhydrazine and azoxymethane, in the host-mediated assay.

Inhibitory effects of several chemicals on the mutagenicities of 1,2-dimethylhydrazine (DMH) and azoxymethane (AOM) for Salmonella typhimurium G46 in the host-mediated assay were investigated. They were carbon disulfide (CS2), tetraethylthiuram disulfide (disulfiram, DSF), sodium diethyldithiocarbamate (SDDC), ethylene-bis(dithiocarbamato) manganese (Maneb), pyrazole (PZ), aminoacetonitrile hydrogen sulfate (AAN), and sodium selenite (SE). All the compounds, except for SE, inhibited the mutagenicities of DMH and AOM.

Aminoacetonitrile↗
PubMed1979

Population genetics of multigene family with special reference to decrease of genetic correlation with distance between gene members on a chromosome.

A mathematical method is developed which enables us to treat exactly the process of coincidental evolution under mutation, unequal intrachromosomal crossing-over as well as ordinary crossing-over between homologous chromosomes in a finite population of the effective size N. It makes use of finite difference equations involving two quantities denoted by fi and phi i, in which fi is the identity coefficient of two gene members that are i steps apart on the same chromosome and phi i is that of two members i steps apart on two homologous chromosomes. When the number of genes (n) per family is large, the finite difference equations can be approximately by ordinary second-order differential equations which can then be solved analytically. Results obtained by the present method are compared with the corresponding results previously obtained by one of us (T.O.) using conventional diffusion models of gene frequency changes in population genetics. It is shown that the previous results obtained by T.O. regarding second-order statistics are essentially valid, and they give good approximations particularly when N beta is small, where beta is the rate of ordinary interchromosomal crossing-over within the multigene family.

Base Sequence↗
PubMed1979

Heterotransplantation of human leukemic B-cell, T-cell and null-cell lines in hamsters.

Human leukemic B-cell (BALL-1), T-cell (TALL-1) and null-cell (NALL-1) lines have been established from three patients with acute lymphoblastic leukemia (ALL). To study the heterotransplantability and in vivo growth characteristics, attempts were made to transplant these ALL cell lines into newborn Syrian hamsters treated with rabbit anti-hamster thymocyte serum. Intraperitoneal implantation of 1.8-3.5 x 10(7) cells gave rise to invasive tumors in all recipients after 15 to 41 days. In addition to a common in vivo feature of mesenteric and retroperitoneal tumors, BALL-1 line was characterized by infiltration of the skin, massive ascites and bone marrow invasion. TALL-1 cells infiltrated various organs including the lymph nodes, liver, gallbladder, spleen, bone marrow, central nervous system and eyes. NALL-1 line grew slowly, producing the least tumors, although there were distant metastases in the lungs. Tumor cells were detected in the blood of 2 of 3 BALL-1-bearing hamsters and in the blood of 4 of 5 TALL-1-bearing hamsters. Thus, these three ALL cell lines were found to exhibit a characteristic biological behavior in hamsters, which might be related to the different cell lineage.

Animals↗
PubMed1979

Low-back pain among electric power supply workers and their attitude toward its prevention and the treatment.

Low-back pain among electric power supply workers and their opinions about the ways to prevent and relieve the disorder were investigated. A questionnaire study revealed that 38.7% of 6,272 electric power supply workers were suffering from low-back pain, including severe pain resulting in frequent absenteeism or requiring occasional rest from work. Chronological analysis of the occurrence of the disorder revealed that the incidence of gradually developing pain has increased and that improper working posture and overwork have become more important as etiological factors. Rest from work was found to be the most effective way of relieving pain, while any medical treatment which did not include rest was useless. Low-back pain among these workers is believed to have resulted from rapid and intensified work as required by increasing demand and mechanization, greater mental stress and improper working posture. As preventive measures, it is necessary to improve working hours and to lighten the rate of work. In order to relieve pain, the employers should permit the workers to absent themselves from work quickly following an attack. Discrepancy between workers' opinions and both actual causation of low-back pain and actual effectiveness of medical treatment is discussed.

Adult↗
PubMed1979

Growth characteristics of human leukemic B-cell, T-cell, and null-cell lines serially transplanted in hamsters.

Human leukemic B-cell (BALL-1), T-cell (TALL-1), and null-cell (NALL-1) lines were established from three patients with acute lymphoblastic leukemia (ALL). Intraperitoneal transplantation of these ALL cell lines into immunosuppressed newborn hamsters resulted in the development of invasive tumors in all recipients, except 4 of 10 implanted with NALL-1 line. BALL-1 and TALL-1 lines were serially transplanted for 10 and 9 passages, respectively. In addition to a common in vivo feature of mesenteric and retroperitoneal tumors, BALL-1 line was characterized by infiltration of the skin, massive ascites, and bone marrow invasion. TALL-1 cells infiltrated various organs including the lymph nodes, liver, bone marrow, central nervous system, eyes, etc. NALL-1 line grew slowly, producing the least number of tumors. Leukemic cells were detected in the blood of 24 of 25 hamsters bearing BALL-1 and in the blood of 18 of 24 hamsters bearing TALL-1. Thus, these three ALL cell lines were found to exhibit a characteristic biological behavior in hamsters.

Animals↗
PubMed1979

Assay for mutagenicity of bile in Sprague-Dawley rats treated subcutaneously with intestinal carcinogens.

To investigate the mode of action of sc injected intestinal carcinogens, the mutagenicity assay of bile collected from noninbred Sprague-Dawley rats treated sc with carcinogens was conducted in the presence and absence of beta-glucuronidase. The bile samples from rats inoculated with 4-aminobiphenyl were mutagenic for Salmonella typhimurium TA100 only in the presence of beta-glucuronidase, whereas those from the 3,2'-dimethyl-4-aminobiphenyl-treated rats did not require the enzyme for mutagenicity toward strain TA100. On the contrary, the assays with S. typhimurium G46 and TA100 of bile from rats inoculated with 1,2-dimethylhydrazine, azoxymethane, or methylazoxymethanol acetate failed to reveal mutagenicity whether beta-glucuronidase was added or not, though these carcinogens were highly mutagenic for strain G46 in the Salmonella-microsome mutagenicity test and/or in the host-mediated assay.

Animals↗
PubMed1979

[Clinical studies on apalcillin in biliary tract infections (author's transl)].

Clinical studies on apalcillin (APPC), a new broad spectrum semisynthetic penicillin developed in Japan, were carried out, and the following results were obtained. APPC was administered to three patients with serious biliary tract infections by intramuscular or intravenous injection at daily dosage of 2. Therapeutic responses were excellent in all cases, and no side effects and abnormalities of laboratory findings were observed. APPC was considered to be an excellent drug for the treatment of biliary tract infections.

Adult↗