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Biomedical subjects

I Yamada

Publications and source records attributed to I Yamada.

180 records · Page 10Linked to original sources

[Anti-DNA analysis].

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Antibodies, Antinuclear↗

Quantification of mitral flow by Doppler color flow mapping.

This study was performed to develop and validate Doppler color flow methods for quantifying forward transmitral flow rates and volumes with isovelocity aliasing contours. We undertook computer modeling of flows and studied an animal model with strictly controlled mitral flows. Finite element analysis was first used to establish the isovelocity surface contours reconstructed from the magnitudes and directions of the velocity vectors proximal to the normal mitral orifice. We modeled finite element-simulated Doppler color flow isovelocity surfaces and computed non-angle-dependent simulated isovelocities to compare them. Then 24 pharmacologically induced hemodynamic states in six sheep in which mitral regurgitation had been previously created surgically were studied. Three methods were used for peak flow (PF) computation: (1) the classic hemispheric methods: PF = 2 pi r2.aliasing velocity; (2) a modified hemispheric method: PF = 2 pi r2.aliasing velocity Vo/Vo-aliasing velocity; and (3) a new segment of sphere method: PF = pi p2.aliasing velocity, where p is the chord from the zenith of the first aliasing contour to the circumference at its base. Mean volume flow was also calculated in combination with phasic flow information from continuous-wave Doppler echocardiography: mean volume flow = PF.VTI/Vmax.heart rate, where VTI and Vmax are the velocity-time integral and maximal velocity of mitral inflow by continuous-wave Doppler echocardiography. Compared with the flow rates obtained by electromagnetic flowmeters, different correlations and agreements were achieved for these methods. Correlation (r = 0.86) and agreement were best for the segment of sphere method for computation of forward mean volume flows in our model. Color flow Doppler quantitation with a segment of sphere or modified hemispheric method appears applicable for quantification of forward transmitral valve flow rates and volumes with reasonable accuracy.

Animals↗

Abdominal macronodular tuberculomas: MR findings.

PURPOSE: Our goal was to determine the appearance of abdominal macronodular tuberculomas on MRI. METHOD: MR findings of two patients with abdominal macronodular tuberculoma, one of the liver and the other in the kidney, were reviewed. RESULTS: The two tuberculomas, histologically confirmed to have no calcification, hemorrhaging, or fibrosis, commonly showed low signal intensity on both T1- and T2-weighted images. CONCLUSION: We report two cases of a macronodular tuberculoma in the liver and kidney, which is visualized as a region of hypointensity on T2-weighted MR images. This finding appears to be important in reaching a definitive diagnosis of an abdominal tuberculoma.

Aged↗

[Disappearance of essential tremor after thalamic infarction].

Stereotactic thalamotomy has been used with some benefit in the treatment of essential tremor. We report a 73-year-old woman whose essential tremor of the right hand spontaneously disappeared after thalamic infarction. She had suffered hand tremor of the right hand for seven years. One morning, she noticed mild muscular weakness in her right upper and lower extremities, numbness around her mouth and paresthesia in her right arm. Simultaneously, she noticed disappearance of the tremor of her right hand. Several days later, right hemiplegia and paresthesia completely resolved. Neurological examination revealed no postural tremor or resting tremor. T 2-weighted brain MR imaging showed a high-intensity signal in the left thalamus that involved the ventralis intermedius nucleus. Clinical recovery from the effect of the infarct on essential tremor was complete. Therefore, it seems that thalamic infarction in this patient had an effect on essential tremor similar to that achieved with thalamotomy.

Aged↗

Surgical results of operations for carcinoma of the gallbladder.

We evaluated the surgical results for carcinoma of the gallbladder. Between 1971 and 1995 we treated 258 patients, 74 of whom were treated with simple cholecystectomy, 71 with extended cholecystectomy, and 24 with more extended operations. The tumors were classified according to the stage proposed by the Japanese Society of Biliary Surgery. For m and pm carcinoma simple cholecystectomy may have an excellent result. However, it is difficult to know cancer depth exactly before or during operation, especially when combined with inflammation due to gallstones. In Stage I disease, extended cholecystectomy had an excellent result. So extended cholecystectomy is needed even in the early stage of the disease. Second operation is needed in inapparent carcinoma of the gallbladder if the tumor is more than pm or the margin is positive. More extended operations may be needed in advanced stages for curative resection. Extended hepatic lobectomy combined with pancreaticoduodenectomy should be indicated only if the patients are in good condition because of its high postoperative mortality and morbidity without a significant improvement in survival.

Adult↗

Thrombectomy for acute deep vein thrombosis: prevention of postthrombotic syndrome.

Ninety-six limbs of 89 patients with acute deep vein thrombosis of the lower extremity were followed for 1 to 18 years. In the thrombectomy group (43 limbs), the cumulative incidence of pigmentation at the 15th year was 15%, but no stasis ulcers occurred throughout the follow-up period. In the conservative treatment group (53 limbs), the cumulative incidence of pigmentation at the 15th year was 41%, and that of stasis ulceration was 27%. Fogarty thrombectomy restricted below the pelvic vein spur and removal of thrombi in the leg veins by manual milking is sufficient to relieve early morbidity, preserve venous valve function, and promote intrapelvic collateral circulation. Preservation of venous valves in the femoropopliteal region is a key to the prevention of postthrombotic syndrome. Thrombectomy within 5 days of the onset of symptoms is recommended for patients with iliofemoropopliteal venous thrombosis.

Adult↗