Luis H. Toledo-Pereyra
Henry Ford Hospital
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Featured researches published by Luis H. Toledo-Pereyra.
European Surgical Research | 1980
Luis H. Toledo-Pereyra; Krishna D. Valjee; Michael Zammit
The role of pancreatic fragment size prior to collagenase treatment, pH, K+ concentration and length of intraportal infusion was studied in islet cell transplantation of streptozotocin-induced diabetic adult rats. This study demonstrates that pancreatic fragments of 1 mm prior to collagenase digestion, pH of 7.4, extracellular potassium concentration and 10 min of intraportal infusion are important factors in successful islet cell transplantation of adult rats receiving six donor pancreases for amelioration of chemical diabetes. These factors should be taken into consideration when consistent islet cell transplantation results are to be expected.
Journal of Surgical Research | 1980
Luis H. Toledo-Pereyra
Abstract Our experiments have attempted to define in a randomized and double-blind fashion some of the important factors involved in freezing of kidneys for transplantation. Only kidneys that were perfused under hypothermic pulsatile perfusion for 6 to 24 hr (with dimethyl sulfoxide, 7.5%), frozen with intraarterial helium and liquid nitrogen, thawed with a rapid microwave thawing technique, reperfused again, and thereafter transplanted showed some evidence of protection. Although 5 out of 10 kidneys showed some evidence of function after grafting, only 3 kidneys functioned with normal creatinine for up to 20 days of follow-up. Kidneys frozen utilizing the current previously available techniques for freezing did not function after transplantation. All the kidneys in this group were not viable after transplantation.
European Surgical Research | 1979
Luis H. Toledo-Pereyra; Vellore R. Ramakrishnan; Michael Zammit
Canine kidneys subjected to 90 min of warm ischemia (37 degrees C) were protected by the administration of methylprednisolone but not by furosemide or mannitol. There was no protective effect observed through the vasodilating or diuretic effect of furosemide in the ischemic canine kidney. Mannitol-induced diuresis before warm ischemia also did not prove to be beneficial for severely ischemic kidneys. Methylprednisolone (30 mg/kg) given 2 h prior to warm ischemia prevented irreversible kidney damage observed in the control and experimental groups. By day 8 the serum creatinine and creatinine clearance returned to normal levels.
Journal of Surgical Research | 1980
Luis H. Toledo-Pereyra; Michael Zammit; Patricia W. Cromwell; Steven Malcom
Donor pretreatment with methylprednisolone (30 mg/kg) and/or glucagon (40 μg/kg) of adult Lewis rats before pancreas harvesting increased the insulin/amylase ratio prior to and after collagenase treatment. The respiratory control index and the number of islet cells were not significantly modified. The results of islet cell transplantation into the portal vein of isologous recipients varied according to the number of donors utilized. Similar results were obtained in animals transplanted with islet cells obtained from six donors whether they were pretreated or not. There were no significant differences in the glycemia post-transplantation when three donors were used for pretreated or control groups. However, animal survival was significantly (P < 0.005) improved in the donor pretreated groups. Donor pretreatment with methylprednisolone and/or glucagon appears to have some effect in stabilizing the release of insulin and amylase from islet cells. Further manipulations with these drugs could be even more helpful in improving islet cell function and survival.
Journal of Surgical Research | 1979
Michael Zammit; Krishna D. Valjee; Luis H. Toledo-Pereyra
Abstract This report confirms the satisfactory results obtained with splenic autotransplantation of islet cells or organ pancreas transplantation. When the allotransplantation technique was utilized, the islet cells rejected significantly faster than the organ pancreas grafts. Rejection in the allotransplant model was correlated with high levels of glucose and amylase at the onset of this phenomenon in the organ graft group and only elevation of glucose in the islet cell group. A progressive increase of these levels was continued after the first rejection was established and this persisted until death. Our data in the dog appear to indicate that islet cell allotransplantation is not justified clinically until better methods to control rejection are introduced. However, islet cell autotransplantation appears to be a good technical advancement in cases with pancreatitis undergoing total or near total pancreatectomy. Organ pancreas transplantation appears to be a good technique for allotransplantation in virtue of our results observed in the dog that has been moderately immunosuppressed.
Immunological Investigations | 1979
Luis H. Toledo-Pereyra; Vellore R. Ramakrishnan
Pretreatment of kidneys with purified Concanavalin A (25 mg/L) allowed for a significant prolongation of survival after allotransplantation in minimally immunosuppressed mongrel dogs. Kidneys pretreated with standard Concanavalin A, impure fraction or the lipopolysaccharide had no prolongation of survival. In fact, the impure fraction and the lipopolysaccharide showed a diminished transplant kidney survival. These studied confirm the beneficial effect of Concanavalin A when the purified form is utilized in modifying kidney allograft survival.
Journal of Surgical Research | 1981
Luis H. Toledo-Pereyra; S. Taiyebb; Gerald H. McKenzie; Debra A. Gordon; Guat S. Sy
Although donor pretreatment has been utilized both experimentally and clinically, its role in conjunction with subsequent hypothermic pulsatile perfusion of renal allografts prior to transplantation has not been clearly defined. This study tests two modes of donor pretreatment and their compatibility with perfusion. Donor dogs were either (1) untreated, (2) pretreated with cyclophosphamide (CY) and methylprednisolone (MP), or (3) pretreated with equine anti-canine antilymphoblast globulin (ALG). Survival and rejection of perfused and nonperfused kidney allografts were compared in an unrelated mongrel dog population using CY and MP or ALG donor pretreatment. Results indicate that the beneficial effects of donor pretreatment with CY and MP are abrogated when kidneys are perfused for 24 hr prior to transplantation (CY + MP, nonperfused, survival = 17.23 ± 4.75, CY + MP, perfused 24 hr, survival = 12.83 ± 3.94 days). Dogs receiving kidneys from donors pretreated with ALG in conjunction with 24-hr pulsatile perfusion, however, demonstrated prolonged renal allograft survival (24.20 ± 10.46 days) (nonpretreated controls, survival = 12.60 ± 3.79 days) (P < 0.001), and the onset of rejection was also significantly delayed (ALG + 24-hr perfusion, graft rejection = 17.87 ± 7.72 days) (non-pretreated controls, graft rejection = 7.87 ± 2.59 days) (P < 0.001). Donor pretreatment of renal allografts with ALG, therefore, appears to be an attractive modality for reduction of graft immunogenicity when perfusion is also utilized prior to transplant.
The Annals of Thoracic Surgery | 1980
Deepak Vij; Luis H. Toledo-Pereyra; Donald J. Magilligan; Fernando M. Jara
This work studies the effect of hyaluronidase on myocardium subjected to long-term aortic cross-clamping (three hours) and moderate hypothermia (28 degrees C). Animals receiving hyaluronidase (1,00o U per liter) through the root of the aorta with a procaine-potassium chloride-lasmalyte cardioplegic solution showed better functional, electrical, and morphological response than the untreated animals. These findings, although preliminary, appear to be promising for potential clinical application.
The Annals of Thoracic Surgery | 1980
Fernando M. Jara; Luis H. Toledo-Pereyra; Joseph W. Lewis; Donald J. Magilligan
At the present time, the major obstacles in the successful clinical application of heart transplantation are the immunological attack on the allograft, the treatment of complications resulting from immunosuppression, and the supply of transplantable hearts. Recently, auxiliary heart transplantation has been proved to be a successful technique for treatment of end-stage myocardial failure in humans. Here we review the experimental work in auxiliary heart transplantation leading to the present technique used in humans.
European Surgical Research | 1980
Fernando M. Jara; Luis H. Toledo-Pereyra
The effect of venting on left atrial pressure and lung water accumulation was studied after prolonged aortic cross-clamping (90 min) and cardiopulmonary bypass in mongrel dogs. Two groups of animals, one with and one without venting, were studied. Left atrial pressure rose significantly (p less than 0.05) in the non-vented animals. This increase, however, did not allow for lung water accumulation or morphological evidence of pulmonary edema. These results appear to indicate that venting is only necessary if a normal left atrial pressure is sought during prolonged aortic cross-clamping. Since the increase in left atrial pressure did not have any detrimental effect on lung morphology or water accumulation, the role of venting under our experimental setting becomes more theoretical than necessary.