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Biomedical subjects

I Koshino

Publications and source records attributed to I Koshino.

23 records · Page 2Linked to original sources
PubMed1975

Analysis of the segmental venous stenosis in blood access.

During in vivo sheep studies on biolized shunts of a unique geometry it was found that venous stenosis was produced in 3 of 3 implants, suggesting its use as a model for the study of this lesion. Hemodynamic data on biolized shunts of different geometry and silicone shunts did not demonstrate significant differences among them. In general, venous side pressures were low and steady. Arterial side pressures upon stabilization were not significantly different than the controls. Time averaged hemodunamic parameters do not appear as dominant differences between the blood access devices evaluated. Angiographic studies indicated that a divergence of flow takes place at the shunt's exist and reveled angulation between the short shunt and the vein. Venous wall immobilization at increased pressures was observed. The tension which causes the wall to be immobilized is beleived to be due to anatomical mismatch between the short shunt and the vascular connection points. Although mechanical stress to the wall, fluid dynamic events and the resultant mass transport processes all may be important in causing the development of the stenotic lesion, the data to date seem to strongly implicate mechanical factors, specifically angualtion and stretching of the vein, in the development of venous stenosis. Local fluid dynamic and mass transfer effects may aggravate the already overstressed vessel.

Animals↗
PubMed1975

A biological extracorporeal metabolic device for hepatic support.

The results from OCTOPUS-I indicate that combined metabolic activities could be maintained under the optimal conditions provided for a prolonged period of time, but most effectively up to 14 hrs. The results of OCTOPUS-II and -III are lower than those in OCTOPUS-I. However, the activity in these systems is still higher than those previously reported((18)), which had urea production of 0.47 mg/Gm of liver. As imposed by any mass transfer device rate limitation, 60% efficacy of OCTOPUS-I brought into OCTOPUS-II, calculated by urea level, is acceptable. What is required for further improvement is mainly oriented to device rather than procurement andpreparation stages. The obstacles in the OCTOPUS-II and -III were, 1) the long time consumed for mounting the slices and assembling the devices before initiation of incubation, 2) inadequate control of incubation media, particularly blood, for oxygenation and pH, which was only for a short period of time but in the critical early stage of operation, 3) possible inadequate flow geometry in the device resulting in mass transfer resistance between the medium and the slices, 4) decrease in effective surface area of the slices, especially in OCTOPUS-III in which only one side of the slice faced the blood, and 5) in OCTOPUS-II, sagging of the slices due to the vertical position of the frames, with eventual reduction of effective surface area. Could a hepatic assist device utilizing liver slices be practical? Daily excretion of urea in dogs is 0.3-0.5 Gm/Kg((31)). Should the urea productivity in OCTOPUS-I(7.2 mg/Gm of liver/24 hrs) be successfully incorporated in a system, 600 Gm of slices can produce the amount of urea equivalent to the daily excretion in a 15 Kg dog. This volume of slices should not be considered unrealistic. Even though it is realized that in the practical situation 60% efficiency is expected, substitution of liver functions does not appear impossible. Further exploration for optimal conditions and practical considerations for improvement of devices will bring the goal closer to reality.

Animals↗