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Biomedical subjects

H Uchida

Publications and source records attributed to H Uchida.

At least 523 records · Page 29Linked to original sources
PubMed1987

Serial evaluation of cardiac function with aortic regurgitation caused by serious aortic lesions. A preliminary comparative study with isolated chronic aortic incompetence.

Clinical and hemodynamic appearances of aortic regurgitation caused by serious aortic lesions (AR-Ao-group) seemed more deteriorated than those with isolated chronic aortic regurgitation (AR-group). Often postoperative course and operative outcome are smooth and satisfactory in the AR-Ao-group. To support this observation, serial changes of left ventricular (LV) function and LV sphericity were evaluated before and after operation in ten cases in the AR-Ao-group and compared with those in the AR-group. Before operation, there were no significant differences in LV function between the two groups. Postoperative improvement of LV sphericity and LV function were statistically better in the AR-Ao-group. The LV function reserve was considered sufficiently retained in the AR-Ao-group. Results with this study supported that clinical observation. Therefore, the total correction, at the same time of aortic incompetence and aortic lesions is recommended.

Adult↗
PubMed1987

Experimental model for predicting metastatic ability of tumors using chick embryo.

At present, there is no established diagnostic method by which the metastatic ability of an individual human cancer can be accurately predicted. We used chicken chorioallantoic membrane (CAM) to predict the metastatic ability of three B16 murine melanoma variant lines and also of human giant-cell carcinoma of the lung. Tumor cells were deposited on the CAM of eggs 10 days after fertilization. On day 7 after the tumor inoculation, the embryos were killed, and the lungs removed, minced and implanted on the CAM of other 10-day-old embryos. On day 7 after this inoculation, the tumors on the CAM were inspected under a surgical microscope, and were also checked histologically. The results accurately reflected the differing metastatic abilities of the B16 melanoma variant lines. Metastases were observed in the lungs of the embryo bearing human giant-cell carcinoma of the lung on the CAM. Using CAM seems to be a suitable way of predicting the malignancy of tumors with metastatic ability.

Animals↗
PubMed1987

Response to antitumor agents of murine transplantable tumors implanted onto chorioallantoic membrane of chick embryo.

The chorioallantoic membrane of chick embryo was used to examine the chemosensitivity of the murine tumors, B16-F1 melanoma, B16-F10 melanoma, Meth-A fibrosarcoma, and Ehrlich carcinoma. The tumors were grown on the membrane, and the effects of 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride, cyclophosphamide, dacarbazine, 5-fluorouracil, methotrexate, adriamycin, mitomycin C, vincristine, and cisplatin on the growth of the tumors were tested by iv injection into a vein of the chorioallantoic membrane or injection into the yolk sac. The use of chick embryo limits the time for drug exposure to 3 or 4 days, but Ehrlich carcinoma and Meth-A fibrosarcoma needed longer for the test; the use of irradiation from a cobalt source overcame the problem by increasing the growth rate of the grafts of these two tumors. There appeared to be a good correlation between the effects of the drugs on B16 melanomas grown in the eggs and in the original animals. Many compounds, including pro-drugs such as cyclophosphamide and dacarbazine, could be assayed in this way.

Allantois↗
PubMed1987

[Canine orthotopic liver transplantation].

For the purpose of increasing long-term survival in canine orthotopic hepatic allotransplantation, immunosuppression by mizoribine and/or cyclosporin was instituted with the following results: 1) The survival of control dogs without treatment (n = 5) was 10.0 +/- 2.9 days (Mean +/- S.E.), and the survival of dogs treated with mizoribine (n = 15) was 44.6 +/- 31.8 days. There was no statistical difference between the two groups. On the other hand, the mean survival of dogs that were initially treated with cyclosporin and were then switched to mizoribine at one to three months after transplantation reached 145.4 +/- 70.8 days. The survival rate of dogs in the cyclosporin-mizoribine group was significantly greater than that of control group (p less than 0.02); and the survival rate of the former group proved also significantly better than that of the mizoribine group at 20 days after transplantation (X2, p less than 0.05); 2) in cases of acute rejection of the allograft, a gradual increase of the serum bilirubin level with a concomitant rise of S-GPT and alkaline phosphatase was generally observed. For an accurate diagnosis, however, an assessment of the biopsy findings of the allograft is important; 3) in chronic rejection, one animal developed the selective disappearance of interlobular bile ducts, often referred to as the "vanishing bile duct syndrome"; and 4) for differential diagnosis of vascular and/or biliary tract complications, specific morphological diagnostic procedures such as vascular and/or biliary tract angiographies are needed.

Animals↗
PubMed1987

Electrophysiological mechanisms for the initiation and maintenance of ventricular fibrillation in nonischemic rabbit hearts.

Two series of experiments were carried out using isolated, perfused rabbit hearts to elucidate the mechanisms of initiation and maintenance of ventricular fibrillation in the absence of ischemia. In the first series, either single premature or rapid electrical stimulation induced ventricular fibrillation, during which the spread of excitation was studied by recording electrograms from the endocardial and epicardial surfaces of both ventricles. Left ventricular endocardial stimulation appeared to induce fibrillation most easily. Initiation of ventricular fibrillation was preceded by the spread of areas showing a conduction delay. In certain instances, excitation of the endocardial and subendocardial tissue was necessary for the maintenance of repetitive responses. Injury to the endocardial and subendocardial layers of a ventricle (or both ventricles) by formaldehyde perfusion made the initiation of fibrillation more difficult, although complete prevention of fibrillation required extensive injury with a significant reduction in the excitable myocardial mass. In the second series of experiments, sustained ventricular fibrillation was produced by rapid electrical stimulation and the effects of several antiarrhythmic agents or electrolytes were studied by recording transmembrane action potentials of subepicardial ventricular muscle fibers with microelectrodes. Quinidine, lidocaine, and high K+ concentration significantly decreased the frequency of cellular depolarization and terminated fibrillation in all the 14 hearts studied. These agents suppressed local responses and small action potentials, and made the action potentials more uniform. In 5 of the 14 hearts in these three groups, termination of fibrillation was followed by either transient or prolonged periods of regular ventricular tachycardia. High Mg2+ concentration and bretylium tosylate tended to hyperpolarize the cell membrane, but less markedly decreased the frequency of cellular discharge. Defibrillation was achieved in only two of the ten hearts in which these two interventions were tested. Lanatoside C shortened the action potential duration, sometimes increased the frequency of cellular depolarization, and tended to sustain fibrillatory movements. These observations suggest the role of numerous microreentry movements in both the initiation and maintenance of ventricular fibrillation, although unifocal, ectopic impulse formation may not be definitely ruled out as an initiating mechanism. The possible defibrillating effect of certain antiarrhythmic agents is suggested.

Animals↗