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Biomedical subjects

K Ohara

Publications and source records attributed to K Ohara.

At least 379 records · Page 21Linked to original sources
PubMed1984

Thermochemotherapy for malignant melanoma: combination therapy of ACNU and hyperthermia in mice.

B16 melanoma (mouse melanoma) and C24 melanoma (human malignant melanoma) transplanted in mice were treated by a combined therapy of ACNU [1-(4-amino-2-methyl - 5 - pyrimidinyl) - methyl - 3 - (2 - chlorethyl) - 3 - nitrosourea hydrochloride] (10 mg/kg) and hyperthermia (43 degrees C, 30 min). In both types of melanoma, a marked synergistic effect of the combined therapy was noted. Particularly in C24 melanoma a reduction in the size of tumor was observed. Histopathologic findings revealed a strong degeneration such as destruction of the tumor structure and vacuolization of nuclei.

Animals↗
PubMed1984

Estimation of rat thermoregulatory ability based on body temperature response to heat.

A new simple but general estimation method for survival time in a hot environment is presented in this study. Even in heat-tolerant rats showing a triphasic heat response, an accurate estimation of survival time (ST) is possible. Rat groups, which included some heat-tolerant individuals, were exposed to 42.5 degrees C, 40% rh. Colonic temperature (Tco) was measured continuously by copper-constantan thermocouple. The ST (Y) of male and female rats were expressed as a linear function of time (X) until the Tco of 42.5 degrees C was reached: Y = 0.976X + 30.6 and Y = 0.968X + 31.6, respectively. A Tco of 42.5 degrees C at rest was just below the maximum survivable body temperature and above the steady-state equilibrium Tco levels during the second phase of the triphasic heat-response curve. Heat-tolerant individuals showed lower equilibrium temperatures than heat-intolerant rats. All 140 rats survived the Tco of 42.5 degrees C and lived for more than 8 wk, thus enabling them to be used for future experiments on thermoregulation. The heat survivors were able to reproduce, and their genetically controlled offspring could be used for thermoregulatory experiments.

Acclimatization↗
PubMed1984

In-vitro and clinical evaluation of cardiac valve substitutes.

One of the major causes of postoperative morbidity and mortality after valve replacement surgery is the prosthetic valve substitute itself. In this discussion, therefore, we make a fundamental evaluation of hydrodynamic valve function and present our clinical results following valve replacement with the Björk-Shiley valve prosthesis, the Hancock porcine xenograft and the Ionescu-Shiley bovine pericardial xenograft. In an experimental study using a mechanical simulator system, the pericardial xenograft displayed superior hydrodynamic characteristics compared to other two valve substitutes. Postoperative hemodynamic evaluation further indicated that the pericardial xenograft performed significantly better than the porcine xenograft regarding transvalvular pressure gradient, effective valve area and cusp opening. In addition, data from 387 patients with aortic, mitral or both types of valve replacement who had received one of the three kinds of valve substitute were analyzed. Systemic thromboembolic complications occurred in one patient with an aortic Björk-Shiley valve (0.6% per patient-year), six with mitral Hancock xenografts (2.8% per patient-year) and one with an aortic and mitral Hancock xenograft (2.2% per patient-year). The incidence of prosthetic valve endocarditis was 0.84% per patient-year for the Hancock xenograft and 1.84% per patient-year for the Ionescu-Shiley xenograft. It was concluded that the hemodynamic and antithrombogenic advantages of the pericardial xenograft proven by our mid-term follow-up study make it the valve substitute of choice. However, careful attention is required regarding prosthetic valve endocarditis tissue heart valves, which are more susceptible to infection than mechanical ones, and the long-term durability of the pericardial xenograft remains to be confirmed.

Aortic Valve↗
PubMed1984

[Left ventricular thrombus formation and cuspal fusion of the prosthetic valve during left heart bypass: their pathophysiological significance and echocardiographic observations].

The echocardiographic findings during left ventricular assist of a heart of a 36-year-old woman who underwent mitral valve replacement were described. Blood was bypassed from the left atrium to the aorta. Echocardiography demonstrated that the pulmonary and tricuspid valves functioned with each heart beat, but that the aortic and prosthetic mitral valves did not open, and the left ventricular wall did not contract. In the left ventricular cavity, there was a mobile and amorphous thrombus which correlated with dynamic intracavitary micro-echoes ("moya moya" echoes). With higher left atrial pressure, the left ventricular motion increased slightly, and the left ventricular dimension gradually decreased. These findings were interpreted as follows: (1) desired results were attained from the previous powerful assist, or (2) the most optimum pressure of the left atrium in relation to the left ventricle was relatively high. It has not yet been determined which is actually the case. The "moya moya" and thrombus echoes were decreased. The general condition of the heart appeared to be improved, but the prosthetic valve motion was not observed. Contrast study via an echocardiographically-guided catheter inserted retrogradely into the left ventricular cavity revealed prosthetic valve stenosis. Fusion of its cusps by fibrin was confirmed on repeat surgery. Although the patient's condition allowed removal of the left ventricular assist device after surgery, the patient died of progressive infection. Optimum powerful assist should be performed while the formation of thrombi and cuspal adhesions is being prevented by other methods, or a more mild assist may be desirable.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

[Primary intracranial hypotension associated with chronic subdural hematoma--report of 2 cases].

Low spinal fluid pressure syndrome is characterized by orthostatic headache aggravated in upright position. It is classified into two from etiological standpoint i.e. primary and secondary (most often seen after lumbar puncture). On the other hand, low spinal fluid pressure is one of the promoting factors of chronic subdural hematoma. We report 2 cases of primary low spinal fluid pressure syndrome (primary intracranial hypotension) associated with chronic subdural hematoma. Case 1 is a 47-year-old man who was admitted with disorientation following 2 week history of orthostatic headache. Spinal fluid pressure was 7mmH2O in the lateral recumbent position. CT scan revealed bilateral isodense chronic subdural hematoma. The subdural hematoma reaccumulated 17 days after the first operation. Case 2 is a 31-year-old woman who was admitted with 4 week history of progressive orthostatic headache accompanied by nausea and vomiting. Spinal fluid pressure was 0 mmH2O. CT scan and cerebral angiography showed bilateral chronic subdural hematoma. The hematoma reaccumulated 20 days after the first operation. Six cases including our two cases of primary intracranial hypotention associated with chronic subdural hematoma have been reported. When changes of characters of headache, especially mental symptoms and disturbances of consciousness occurred in patients with chronic orthostatic headache, association of chronic subdural hematoma should be suspected. In cases with chronic subdural hematoma associated with low spinal fluid pressure syndrome, the reaccumulation of hematoma tends to occur after burr hole opening and irrigation of hematoma.

Adult↗
PubMed1983

Comparison of efficacy of timiperone, a new butyrophenone derivative, and clocapramine in schizophrenia: a multiclinic double-blind study.

The clinical efficacy and safety of timiperone, a new butyrophenone derivative, on chronic schizophrenia was compared with clocapramine by the double-blind method using a total of eighty-eight patients, consisting of forty-four patients in each group. In the final global improvement rating, the global improvement rating in each week and the general usefulness rating, there were no statistically significant differences between the two groups. However, in the global improvement rating in each symptom, timiperone was significantly superior to clocapramine in delusion and showed a superior tendency to clocapramine in contact. Timiperone showed a higher improvement rate than clocapramine in hallucination and disturbance of self-consciousness. In the over-all safety rating, there were no significant differences between the two groups, but in accompanying symptoms and side-effects, timiperone showed significantly less tendency than clocapramine in dyskinesia, insomnia, constipation and nausea. From these results, including the analysis by stratification, it was considered that timiperone was a superior or equivalent neuroleptic in comparison with clocapramine against the negative symptoms as well as the positive ones of chronic schizophrenia, and was equally safe or safer than clocapramine.

Adolescent↗
PubMed1983

[Intra-operative irradiation of solid tumors in children].

For the purpose of getting better therapeutic ratio of radiation therapy, an intra-operative irradiation was scheduled and attempted. The advantages of this modality are 1) only the target area is irradiated under the direct vision, 2) unnecessary area is not irradiated due to the selected field and selected electron beam energy, and 3) repeated fractionated irradiation are not necessary and an intensive post-operative chemotherapy can be started earlier. Electron beams of betatron are used according to the necessary depth of tumor volume: usually 8 or 10 MeV are used. The irradiation fields changed by the plastic treatment cones 4 cm to 12 cm in diameter according to the necessary tumor field. One of the biggest problems in an actual attempt of intraoperative irradiation was the determination of a single radiation dose. Actual time-dose relationship of the cured cases of Wilms' tumor and neuroblastoma was investigated by world literature. The single doses for 2 years old patients were calculated from Ellis' formula. They were 9.4-11.8 Gy for Wilms' tumor and 6.5-12.2 Gy for neuroblastoma. Consequently, the single dose was started from 10 Gy and increased up to 15 Gy at the present time. External irradiation was scheduled for supplement if necessary. The details of irradiation on 5 cases were discussed. The clinical evaluation of this treatment method will take time, and many problems remain to be solved clinically and experimentally, such as the radiation effect and side effect of a large single dose.

Adolescent↗
PubMed1983

[Effects of a combination chemotherapy "VEMA" consisting of vincristine, cyclophosphamide, methotrexate and ACNU in the treatment of small cell bronchogenic carcinoma].

A combination chemotherapy "VEMA" consisting of vincristine (VCR), cyclophosphamide (Endoxan, EX), methotrexate (MTX) and nimustine (ACNU) has been carried out for the treatment of small cell bronchogenic carcinoma since September, 1978. "VEMA" regimen consists of VCR 1.3 mg/m2 iv push on day 1, EX 500 mg/m2 iv infusion on day 1 and 2, MTX 28 mg/m2 iv push on day 1, 2 and 3, and ACNU 67 mg/m2 iv push on day 3. This dose schedule was repeated every 3 to 4 weeks. The regimen was given to 14 patients and 12 patients were evaluable. In the 12 evaluable cases, 2 case of complete response (CR), 7 cases of partial response (PR) and 2 cases of effusion effective were obtained. Response rate of CR + PR was 90%. Response rate including CR, PR and effusion effective was 91.7%. The major clinical toxicity of "VEMA" therapy was bone marrow suppression. Other side effects were anorexia, nausea, vomiting, alopecia and stomatitis: etc; however, these side effects were not life threatening to terminate "VEMA" therapy. In conclusion, "VEMA" regimen is a new potent combination chemotherapy in the treatment of small cell bronchogenic carcinoma.

Adult↗
PubMed1983

[Phase II study with methyl-6[[[2-chloroethyl) nitrosoamino] carbonyl] amino]-6-deoxy-alpha-D-glucopyranoside (MCNU) in hematological malignancies].

A total of 117 cases with hematological malignancies were treated with MCNU at doses of 70-100 mg/m2. Following are the results obtained. 1. MCNU showed a marked depression of cells in the cases with CML, polycythemia vera and thrombocythemia. The low level of cells was maintained for 2 to 7 months. 2. A good response was observed in several cases with blastic crises of CML. 3. No response was observed in two cases with acute leukemia. 4. Although a fair response was observed in several cases with malignant lymphoma or multiple myeloma, moderate bone marrow suppression was observed in a majority of the cases.

Adult↗