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N Morikawa

Publications and source records attributed to N Morikawa.

At least 109 records · Page 6Linked to original sources
PubMed1979

[Development of high-sensitivity radio gas chromatography--specific characteristics of a long path internal gas flow proportional counter (author's transl)].

A long path internal gas flow proportional counter was devised was to be used as a high sensitivity detector for radio gas chromatography, and its performance characteristics were investigated. The long path counter tube used for this detector has a sufficiently long passage in comparison with the diameter. The counter tube for general use is made of brass or copper tube 1 cm in diameter, 100 cm in length with a mirror finish on all internal surface, and the center electrode is of tungsten wire 0.05 mm in diameter. For actual use, several of these counter tubes are connected in series in assembly to hold the total volume of a gas sample in the counting system over a desired counting period. Thus this flow detector as an integral type one and gives directly a counting rate. Experiments showed that the dynamic counting efficiencies of tritium and carbon-14 were about 90% and equal to the static counting efficiencies. Furthermore, with this detector, the counting rate does not appear to be affected by minor variations of the effective inner volume of the counter tube and the flow rate of counting gas.

Carbon Radioisotopes↗
PubMedDate not supplied

A newly developed three-layer agarose microcapsule for a promising biohybrid artificial pancreas: rat to mouse xenotransplantation.

We examined the effectiveness of an improved version of a three-layer agarose microcapsule in islet xenotransplantation. The microcapsule is composed of a mixture of 5% agarose and 5% polystyrene sulfonic acid. The other two outer layers are polybrene and carboxymethyl cellulose. The agarose/polystyrene sulfonic acid membrane is for the purpose of immunoisolation, suppression of complement activity and reinforcement of the microcapsule. The polybrene layer suppresses the polystyrene sulfonic acid leakage by forming a polyionic complex at the surface of the agarose/polystyrene sulfonic acid membrane. The outermost layer, a carboxymethyl cellulose coating, improves the biocompatibility of the microcapsule. In vitro static incubation study showed that the insulin secretion from rat islets in microcapsules in response to 16.7 mM glucose stimulation was more than four times higher than that on 3.3 mM glucose stimulation (n = 8). In an in vivo study, 500 rat islets in microcapsules were xenogenically implanted in the abdominal cavity of mice with streptozotocin-induced diabetes. The graft survival times ranged from 2 to 5 mo, the average being 75 days (n = 5). Our results demonstrate that the improved version of the three-layer agarose microcapsule can effectively prolong the xenograft survival time without employing immunosuppressants, suggesting that this microcapsule could provide a promising biohybrid artificial pancreas for future clinical applications.

Animals↗