Continuous recirculating peritoneal dialysis (CRPD) was newly introduced to improve solute removal efficiency in conventional dialysis therapies such as hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD). In CRPD, a part of the dialysate in the peritoneal cavity was drained through a double-lumen catheter and purified by an extracorporeal dialyzer. Urea removal characteristics in CRPD were examined in a canine study. In this study, a recirculation-dialysis experiment using a dog weighing 9.0 kg was carried out under 100 and 200 ml/min of flow for recirculating and delivered dialysates, respectively. An FB-50H (Nipro Medical Industries, Ltd., Osaka, Japan) composed of cellulose diacetate membrane with 0.5 m2 of surface area and Dianeal-1.5 (Baxter Limited Laboratories, Tokyo, Japan) containing urea were used as the extracorporeal dialyzer and dialysate. Urea peritoneal and dialyzer dialysances (DBP and DBD) were 3.05 and 33.3 ml/min by computer simulation using a compartment model for CRPD. This DBP value can be estimated as 20.3 ml/min for a 60 kg human. From this result, time-averaged value for BUN over an 8 hr/day CRPD, combined with three exchanges/day as CAPD is estimated to be 34.3 mg/dl, which is much lower than 45.2 mg/dl for a 12 hr/week HD, or 53.0 mg/dl for conventional CAPD.

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PubMedDate not supplied

Prolongation of cardiac xenograft survival by double filtration plasmapheresis and ex vivo immunoadsorption.

A double filtration plasmapheresis (DFPP) technique and ex vivo immunoadsorption were applied to remove natural antibodies and avoid hyperacute rejection in discordant xenotransplantation. A swine heart was heterotopically transplanted into a dog's neck after DFPP and ex vivo immunoadsorption using a swine spleen or liver. Mean graft survival time was prolonged to 240 +/- 141 min in the group treated by combined DFPP and splenic adsorption, and 225 +/- 62 min in the group treated by combined DFPP and hepatic adsorption, whereas it was 9 +/- 5 min in the group without any treatment (p < 0.01). Mean removal rates of IgG and IgM were 85.5% and 93.3%, respectively. Anti-swine lymphocytotoxic antibodies and hemagglutination antibodies were also effectively removed. Deposits of canine IgM and C3 on the vascular endothelium of the graft were observed on immunofluorescence, which suggested that natural antibodies in the IgM fraction played an important role in xenohyperacute rejection.

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PubMedDate not supplied

Effect of ischemia on hydroxylase cofactor (tetrahydrobiopterin) and monoamine neurotransmitters in rat brain.

Hydroxylase cofactor, monoamine neurotransmitters and their metabolites were measured in ischemic rat brain produced by four-vessel occlusion for 30 and 60 min periods. Slight reduction of hydroxylase cofactor activity was observed in the ischemic cortex after 60 min. Dopamine increased in the brainstem, and its metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, increased throughout the brain. Decrease in norepinephrine was observed in the whole brain. Decrease in serotonin and increase in 5-hydroxyindoleacetic acid, a metabolite of serotonin, was observed in the ischemic cerebral cortex. The present study has revealed that there appears to be no significant relationship between hydroxylase cofactor activity and monoamine levels in the ischemic brain. Thus, the hydroxylase cofactor does not play a main role in regulating monoamine synthesis in the acute phase of brain ischemia.

3,4-Dihydroxyphenylacetic Acid↗

PubMedDate not supplied

Prolongation of cardiac xenograft function after reduction of natural antibodies using double filtration plasmapheresis.

A double filtration plasmapheresis (DFPP) technique was applied to selectively remove the natural antibodies in discordant xenotransplantation. A swine heart was heterotopically transplanted in a canine neck after two DFPP procedures during which 200 to 500 ml of plasma were replaced with the same amount of Hartman's solution containing 7% human albumin. Mean removal rate of IgC and IgM by DFPP ranged from 74.2 +/- 0.5 to 95.9 +/- 2.8%. The anti-swine lymphocytotoxic reaction of canine serum was decreased after DFPP but still remained in low titers. Mean graft survival time in the group treated by DFPP in which 1000 ml of plasma was totally replaced was prolonged to 107 +/- 47 min, while it was 9 +/- 5 min in the group without any treatment (p less than 0.01). Deposits of canine IgM and C3 on the vascular endothelium of the graft were observed on immunofluorescence, while there were no deposits of IgG. In conclusion, DFPP effectively removed the natural antibodies, resulting in prolongation of xenograft survival time. Immunofluorescence study suggested that natural IgM antibodies played an important role in this xeno-hyperacute rejection.

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PubMedDate not supplied

Cardiac function of an acute ischemic heart failure model produced by microsphere injection into the left coronary artery. Pressure-volume relationship as determined by a conductance catheter.

The authors produced an acute canine heart failure model by injecting microspheres (phi 15.5 +/- 0.1 mm, 5 x 10(5)) into the left coronary artery, and characterized the model in terms of the pressure-volume relationship obtained by the conductance catheter method. Cardiodynamics of the microsphere injection group (M group: n = 10) and control group (C group: n = 12) were studied with 1) heart rate, 2) aortic pressure, 3) cardiac output (CO), 4) maximal ventricular elastance, 5) effective arterial elastance/maximal ventricular elastance, and 6) external work/pressure-volume area efficiency. With microsphere injection, CO and external work/pressure-volume area efficiency significantly decreased. With administration of dobutamine (5 mg/kg/min), CO and maximal ventricular elastance recovered to normal and aortic pressure became higher than normal. These changes in heart rate, aortic pressure, CO, maximal ventricular elastance, and external work/pressure-volume area efficiency in the M group were comparable in percentage to those in the C groups. Cardiodynamics of this heart failure model generally were stable for 3 hrs after microsphere injection. The authors concluded that this model would be an excellent acute heart failure model for investigating hemodynamic effects of circulatory assist devices.

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