Search PubMed⌕ Search

Biomedical subjects

R R Bollinger

Publications and source records attributed to R R Bollinger.

117 records · Page 7Linked to original sources
PubMed1975

Prevention of decompression sickness during a simulated space docking mission.

This study has shown that repetitive exchanges between the American Apollo space vehicle atmosphere of 100% oxygen at 5 psia (258 torr) and the Russian Soyuz spacecraft atmosphere of 30% oxygen-70% nitrogen at 10 psia (523 torr), as simulated in altitude chambers, will not likely result in any form of decompression sickness. This conclusion is based upon the absence of any form of bends in seven crewmen who participated in 11 tests distributed over three 24-h periods. During each period, three transfers from the 5 to the 10 psia environments were performed by simulating passage through a docking module which served as an airlock where astronauts and cosmonauts first adapted to each other's cabin gases and pressures before transfer. Biochemical tests, subjective fatigue scores, and the complete absence of any form of pain were also indicative that decompression sickness should not be expected if this spacecraft transfer schedule is followed.

17-Hydroxycorticosteroids↗
PubMed1975

Biomedical cost of low-level flight in a hot environment.

The physiologic and performance effects of low-level reconnaissance flying in hot environments were documented and quantitated. RF-4C pilots and weapons system operators were studied in hot and cool seasons during both high and low missions to distinguish environmental temperature from flight level effects. ECG, sternal and thigh skin temperatures, and cockpit temperature at helmet level were monitored continuously. Body weights, oral temperatures, sweat Na/K ratios, and urine electrolytes, steroids, and catecholamines, as well as sleep and fatigue scores, were measured. Mission performance was assessed using photo target acquisition scores. RF-4C aircrews are exposed to moderate heat stress and acute dehydration (1.2% over 90 min) during low-level summer flights were cockpit temperature occasionally exceeded 50 degrees C. Photo target scores indicated that the potential for crew error was increased, and that the margin of safety was accordingly decreased, during such hot missions. The RF-4C cockpit air conditioning system proved inadequate.

Aerospace Medicine↗
PubMedDate not supplied

Alpha 1-adrenergic effects and liver regeneration.

The effects of several treatments involving alpha-adrenergic mechanisms upon the early stages of rat liver regeneration were examined. Catecholamine concentrations in rat plasma were measured at various times after hepatectomy and were found to be elevated relative to those in plasma from sham-operated rats. Surgical hepatic denervation or injection of an alpha 1-adrenergic receptor antagonist (prazosin) reduced incorporation of [3H]thymidine into liver DNA during the first 24 hr after partial hepatectomy. Chronic guanethidine injections (3 to 6 weeks) reduced liver catecholamine levels, but did not affect its ability to regenerate. The inhibition of regenerative DNA synthesis by prazosin was preceded by an alteration in the binding of epidermal growth factor to regenerating liver, which was apparently the result of an increased number of epidermal growth factor receptors. Thus, alpha 1-adrenergic blockade, which affects both epidermal growth factor receptor binding and subsequent DNA synthesis in hepatocyte primary cultures, can also modulate these processes during liver regeneration in vivo.

Animals↗
PubMedDate not supplied

A randomized study comparing leukocyte-depleted versus packed red cell transfusions in prospective cadaver renal allograft recipients.

A prospective randomized study at a single renal transplant center between 1980 and 1982 compared the influence of leukocyte-depleted versus packed red cell pretransplantation blood transfusions on patient sensitization to leukocyte (HLA) antigens, likelihood of receiving a graft, and eventual transplantation results. All consenting potential cadaver renal transplant recipients (n = 107) were randomly assigned to receive transfusions at 6-week intervals with either packed red cells (Group 1) or leukocyte-poor red cells (Group 2) until they were transplanted. Actuarial graft and patient survival were identical for graft recipients in both groups. Although the likelihood of receiving a graft was associated with the level of pretransplant sensitization to leukocyte (HLA) antigens (p less than 0.02) as measured by the percent of panel reactive antibody (PRA), it was not associated with the type of blood used. The highest mean peak reactive PRA level for all patients showed a low but significant increase (29 +/- 4 versus 43 +/- 5%; p less than 0.0005) following entry into the transfusion protocol, but the rate of increase was the same for patients in both treatment groups. The likelihood of receiving a transplant was primarily associated with a history of prior graft rejection (p less than 0.05), and patients with prior graft loss had the greatest increase in sensitization following entry into the transfusion protocol. These findings indicate that using leukocyte-poor red cells for pretransplant transfusions provided no added benefit when compared with packed red cells in terms of patient sensitization, the likelihood of receiving a transplant, or eventual graft survival.

Actuarial Analysis↗
PubMedDate not supplied

Prolonged heart xenograft survival using combined total lymphoid irradiation and cyclosporine.

Total lymphoid irradiation and cyclosporine have profound immunosuppressive properties and permit successful heart allotransplantation. Cyclosporine used alone has not permitted consistently successful transplantation between species in all cases. Total lymphoid irradiation has not been applied to xenotransplantation. The efficacy of total lymphoid irradiation alone and in combination with cyclosporine was examined using an animal model of heart xenotransplantation. Heterotopic heart transplants were performed using inbred Syrian hamsters as donors and Lewis rats as recipients. Total lymphoid irradiation was administered preoperatively over 3 weeks for a total dose of 15 gray. Cyclosporine was started on the day of surgery and was given as a daily intramuscular injection of 2.5, 5, or 10 mg/kg/day until rejection was complete. Neither total lymphoid irradiation nor cyclosporine alone markedly prolonged graft survival. However, combined total lymphoid irradiation and cyclosporine, 5 or 10 mg/kg/day, dramatically prolonged graft survival to greater than 100 days in most recipients. There were no treatment-related deaths. In conclusion, combined total lymphoid irradiation and cyclosporine permit successful long-term survival of heart xenotransplants in this hamster-to-rat model.

Animals↗
PubMedDate not supplied

The effect of cyclosporine, total lymphoid irradiation, and cobra venom factor on hyperacute rejection.

Transplantation into sensitized recipients is contraindicated due to the potential for hyperacute rejection. In order to study the mechanism of hyperacute rejection and the role of immunosuppression in the face of presensitization, we evaluated the effect of total lymphoid irradiation, cyclosporine, and cobra venom factor, alone and in combination, on hyperacute rejection of heterotopic rat heart allografts. Lewis rats were sensitized to strongly RT-1-incompatible ACI rats by three successive skin grafts. Heart allografts were then performed, and survived for a mean period of 15.7 +/- 7.4 hours. Neither preoperative treatment of hypersensitized rats with total lymphoid irradiation alone nor with cyclosporine (5 mg/kg/day) resulted in a prolongation of survival (20.4 +/- 16.6 hours and 35.6 +/- 6.2 hours, respectively). However, complement depletion using cobra venom factor significantly prolonged mean graft survival time to 114.4 +/- 31.0 hours (p less than 0.05). Cyclosporine (10 mg/kg/day) also significantly prolonged survival to 149 +/- 29 hours (p less than 0.01), but did not lower the antibody or complement levels. The addition of total lymphoid irradiation or cyclosporine to treatment with cobra venom factor did not result in longer survival than cobra venom factor alone. In conclusion, cobra venom factor and cyclosporine delay but do not prevent hyperacute rejection, while total lymphoid irradiation has no observable effect on hyperacute rejection.

Animals↗