Biomedical subjects
P Tzardis
Publications and source records attributed to P Tzardis.
Beneficial and detrimental effects of RBC-adsorbed antilymphocyte globulin and prednisone on purified canine islet autograft and allograft function.
We have examined the effects of prednisone, cyclosporine, azathioprine, and RBC-adsorbed goat antidog antilymphocyte globulin on islet graft function in totally pancreatectomized canines with purified, quantitatively defined, autologous, or allogeneic islets transplanted to the liver. The objectives were twofold: (1) to determine the potential detrimental effects to islet autograft function of the aforementioned agents, and (2) to determine the relative efficacy of the "nontoxic" agents in prolonging purified islet allograft function administered in doses that would be considered tolerable in human. The islet autograft studies demonstrated that prednisone given in doses of 1-2 mg/kg/day had a detrimental effect on islet autograft function, and that the combinations of immunosuppression involving CsA, azathioprine, and ALG were not detrimental to islet autograft function to the extent that hyperglycemia would ensue. In the subsequent allograft studies, three groups of canines received islet transplants: (1) controls (n = 5; 7860 +/- 750 islets/kg/weight), (2) canines given CsA and azathioprine (n = 6; 6810 +/- 890 islets/kg/body weight), and (3) canines given CsA, azathioprine, and RBC-adsorbed goat antidog ALG (n = 8; 6540 +/- 710 islets/kg/body weight). The mean (+/- SE) day of rejection (serum glucose greater than or equal to 200 mg/dl) in the group of canine islet allograft recipients receiving CsA, azathioprine, and ALG was 11.8 +/- 1.4 days--significantly prolonged versus islet allograft recipients receiving no immunosuppression (mean survival 4.8 +/- 1.1 days, P less than 0.03), and versus allograft recipients receiving CsA/azathioprine without ALG (mean survival 4.4 +/- 1.4 days, P less than 0.05). Prednisone appears to be detrimental to islet graft function, even at low doses. ALG was not toxic, and significantly extended the survival of canine islet allografts. The inclusion of steroids as part of maintenance immunosuppression, or as treatment for acute rejection of islets, in human islet transplants should be reconsidered, whereas ALG or other antilymphocyte agents should continue to be used.
Total pancreatectomy in the pig for islet transplantation. Technical alternatives.
Pigs appear to be a suitable biological and logistical animal donor of islets for xenotransplantation in human diabetic type I recipients. To improve the islet isolation technique in this species, to evaluate the islet function in vivo, and to assess the toxic effects of various immunosuppressive regiments on transplanted islets will necessitate a model of the pancreatectomized pig suitable for islet autotransplantation. We describe three techniques of total pancreatectomy in pigs. The first removed the pancreas in order to study postoperative management and pig survival; no attempt was made to preserve the pancreas for islet isolation. The second consisted of a pancreatectomy in a surviving pig, with careful preservation of the whole pancreas for subsequent islet isolation. The third was rapid en bloc procurement of the pancreas and duodenum, to obtain a pancreas solely for the purpose of islet isolation. We conclude that pigs tolerate and survive a total pancreatectomy--they are suitable animals for islet isolation and possible autotransplantation. The result of islet isolation does not appear related to the pancreas procurement technique; however, the islet yield must be improved before autotransplantation can be functionally successful.
Cancer development in renal allograft recipients treated with conventional and cyclosporine immunosuppression.
Explore the source record for details and available documents.
De novo cancer after pediatric kidney transplantation.
Explore the source record for details and available documents.
Islet xenotransplantation in a pre-clinical large animal model.
Explore the source record for details and available documents.
Changing pattern of distribution of carcinoma of the stomach.
Explore the source record for details and available documents.
Canine islet autografts: functional outcome as influenced by islet number and purity.
Explore the source record for details and available documents.
Pharmacodynamics of local heparin infusion in a canine renal allograft model.
Inasmuch as heparin has demonstrated immunosuppressive activity in vivo and in vitro, we utilized a canine renal transplant model to estimate the first-pass extraction of heparin during renal artery infusion and to examine the effect of regional heparin delivery on the histologic features of rejection and allograft survival. Four autotransplanted mongrel dogs with programmable, implantable pump/catheter systems received a continuous intrarenal heparin infusion which was increased daily in stepwise fashion. Activated coagulation time (ACT) rose linearly with local heparin dose, indicating that heparin clearance remained constant over the dosage range studied. Comparison of these ACT values with those measured during same-dose i.v. infusion and those predicted from i.v. bolus studies revealed that there was little or no first-pass renal extraction of heparin by the transplanted kidney. In nine allografted dogs, the heparin infusion rate was adjusted according to daily ACT to maximize local heparin delivery but still maintain the ACT close to 125% of base line. There was no difference in overall survival between the heparin-treated dogs and a group of 14 untreated controls, and vascular rejection was significantly more intense in the heparin-treated animals. We conclude that intrarenal dosing of heparin to the point of producing systemic anticoagulation is limited by failure of the transplanted kidney to eliminate drug and does not prolong canine renal allograft survival.
Overwhelming postsplenectomy infection in patients with thalassemia major.
The efficacy of pre- and post-operative protection against overwhelming postsplenectomy infection was evaluated in a prospective study of 98 patients with thalassemia major. All patients were vaccinated four to ten weeks pre-operatively with a polyvalent antipneumonococcal vaccine; after their discharge from the hospital they received 1,000,000 units (625 mg) of oral penicillin daily for one to two years and have been closely followed up since then. The incidence of overwhelming infection among our patients was 1.02%. This very low incidence suggests that vaccination and prophylactic penicillin administration, combined with careful follow-up, provide adequate protection against overwhelming infection in splenectomized patients with thalassemia major.
Thyroglossal duct cyst carcinoma (report of two cases).
Two cases of papillary carcinoma of thyroglossal duct cyst that were treated in our department are presented. Differential diagnosis and pathological features are emphasized. Radical excision of the cyst according to Sistrunk's technique is recommended. The recent literature concerning this subject is reviewed.