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Biomedical subjects

A Tzakis

Publications and source records attributed to A Tzakis.

At least 145 records · Page 8Linked to original sources
PubMed1993

The effect of prednisone on pancreatic islet autografts in dogs.

Prednisone was shown to induce hyperglycemia in dogs submitted to total pancreatectomy and pancreatic islet autotransplantation. The hyperglycemia caused by a 10-day course of prednisone, 1 mg/kg/day, starting on the day of operation was reversible within 1 week after steroid discontinuance. Three weeks after prednisone was stopped, there was no detectable adverse effect on glucose homeostasis as judged by fasting blood sugar levels and intravenous glucose tolerance test results. Four months after transplantation, glucose disappearance was delayed in animals previously treated with the prednisone compared with those previously treated with prednisone plus insulin or control animals. This was accompanied by lower insulin values on intravenous glucose tolerance testing and suggests a long-term subtle effect on islet function. The mechanism of the steroid effect is not known. However, this model could be used to test the diabetogenicity of other immunosuppressive agents including cyclosporine, FK 506, and azathioprine.

Animals↗
PubMed1992

Orthotopic liver transplantation for urea cycle enzyme deficiency.

Hyperammonemia, abnormalities in plasma amino acids and abnormalities of standard liver functions were corrected by orthotopic liver transplantation in a 14-day-old boy with carbamyl phosphate synthetase-I deficiency and in a 35-yr-old man with argininosuccinic acid synthetase deficiency. The first patient had high plasma glutamine levels and no measurable citrulline, whereas citrulline values were markedly increased in Patient 2. Enzyme analysis of the original livers showed undetectable activity of carbamyl phosphate synthetase-I in Patient 1 and argininosuccinic acid synthetase in Patient 2. Both patients were comatose before surgery. Intellectual recovery of patient 1 has been slightly retarded because of a brain abscess caused by Aspergillus infection after surgery. Both patients are well at 34 and 40 mo, respectively, after surgery. Our experience has shown that orthotopic liver transplantation corrects the life-threatening metabolic abnormalities caused by deficiencies in the urea cycle enzymes carbamyl phosphate synthetase-I and argininosuccinic acid synthetase. Seven other patients--six with ornithine transcarbamylase deficiency and another with carbamyl phosphate synthetase-I deficiency--are known to have been treated elsewhere with liver transplantation 1 1/2 yr or longer ago. Four of these seven recipients also are well, with follow-ups of 1 1/2 to 5 yr. Thus liver transplantation corrects the metabolic abnormalities of three of the six urea cycle enzyme deficiencies, and presumably would correct all.

Adult↗
PubMed1992

Composition of human islet cell preparations for transplantation.

To study the cellular composition of human islet cell isolates for transplantation, formalin-fixed and paraffin-embedded cell pellets were stained by the immunoperoxidase method with a panel of antibodies characterising endocrine, epithelial, soft tissue and haematolymphoid components. Immediately after separation, the isolates contained 30-80% islet cells, differing mainly in the content of islet and acinar cells, whereas the soft tissue, ductal/ductular and haematolymphoid elements comprised a relatively constant 10-20%. After 1 week in culture the islet cell content of less highly purified isolates (30-40% islets) dropped dramatically to 5%. The highly purified isolates (70-80% islets) showed only a minimal change in cellular composition; however, approximately two-thirds of islet cells were degranulated and did not stain for insulin. Haematolymphoid components were still present in all cultured isolates. We conclude that primarily mechanical purification methods and short-term culture are not sufficient to eliminate highly immunogenic cells. In addition, short-term culture is deleterious to the isolate if a significant number of acinar cells is still present after enrichment.

Adult↗
PubMed1992

Resection, including transplantation, for hepatoblastoma and hepatocellular carcinoma: impact on survival.

Long-term survival in children with primary hepatic malignancies can not be expected without complete tumor resection. In the last ten years we have treated 21 children with hepatocellular carcinoma (HCC) and 21 children with hepatoblastoma (HEP), with tumor extirpation our surgical goal. Operative treatment included partial hepatectomy ([PH] 20), either primary (10) or delayed (following chemotherapy) (10), total hepatectomy and orthotopic liver transplantation ([OLT] 13), or upper abdominal exenteration and multiple organ transplantation (2). Two patients had both PH and subsequent total hepatectomy and OLT. Overall survival was 48% (20/42), with 9 patients dying of progressive disease prior to removal of their tumor. HEP patient survival was 67% (14/21), including 2 of 6 who underwent primary PH, 7 of 8 who had delayed PH, and 5 of 6 who underwent OLT. Survival for the children with HCC was 29% (6/21), including 1 of 4 after primary PH, 1 of 2 following delayed PH, 3 of 7 following OLT, and 1 of 2 after exenteration and multiple organ transplantation. Preoperative chemotherapy facilitated removal of 10 initially unresectable tumors (8 HEP, 2 HCC) at a second-look procedure. Total hepatectomy and OLT markedly improved survival in patients with disease unresectable by standard methods. Partial hepatectomy, either primary or delayed, should be attempted in all children with hepatic malignancies. Total hepatectomy and OLT appears to be a viable adjunct in the treatment of childhood malignancies, and should be used for otherwise unresectable tumors as part of a carefully planned protocol.

Antineoplastic Agents↗
PubMed1992

Pediatric renal transplantation under FK-506 immunosuppression.

Renal transplantation (11 cadaveric and 1 living-related donor) was performed in 12 pediatric recipients (mean age 10.8 years) under FK-506 immunosuppression in combination with prednisone therapy. At a mean followup of 6.1 months, patient and graft survival rates were 100% and 92%, respectively. The only graft loss was due to the recurrent hemolytic uremic syndrome 4 days after transplantation. In the functioning grafts the mean serum creatinine is 1.59 +/- 1.27 mg./dl. and the mean blood urea nitrogen is 36.3 +/- 24.6 mg./dl. Three patients take no prednisone, 5 are receiving 0.15 to 0.25 mg./kg. per day and 3 are taking 0.35 to 0.5 mg./kg. per day. There was a total of 8 rejection episodes in 5 patients. All rejection episodes were successfully reversed. Complications of transplantation included an episode of seizures in 1 patient, cytomegalovirus infection in 1 and steroid-induced diabetes mellitus in 1. Since pediatric transplant recipients are a group in whom the reduction or elimination of steroids is highly desirable, FK-506 immunosuppression may be particularly suited for use in this population.

Adolescent↗
PubMed1992

Logistics and technique for combined hepatic-intestinal retrieval.

During a 13-month period, en bloc liver-small bowel cadaveric grafts were procured for seven children and one adult. All liver grafts functioned immediately, and all but one of the recipient patients recovered. Return of absorptive small bowel function was slow, but the integrity of the bacterial intestinal barrier was not disrupted. The described technique allows the procurement of other abdominothoracic organs, with the exception of the whole pancreas.

Adolescent↗
PubMed1992

Detection of intrahepatic human islets following combined liver-islet allotransplantation.

This article describes the localization of intact insulin-containing intrahepatic islets after combined liver-islet allotransplantation. The patient was a 36-year-old woman who underwent upper abdominal exenteration for neuroendocrine carcinoma; 289,000 islets were transplanted via portal vein infusion immediately after complete revascularization of the liver. Immunosuppression was with low-dose FK-506. OKT3 and steroids were used to treat one rejection episode 2 weeks after transplantation, but the patient subsequently developed multiple infections and died 109 days after transplantation. At autopsy, the transplanted liver did not show any sign of rejection and well-preserved islets were present in portal triads sampled from the anterior inferior edge of the right lobe. Immunohistochemical labeling confirmed the presence of insulin-containing cells. This finding indicated that human islets can survive after intrahepatic allotransplantation, despite positive cross-match with no HLA antigen match, suggesting that upper abdominal exenteration and liver transplantation may constitute a protective factor for the survival of allogeneic human islets.

Adult↗
PubMed1992

Long-term survival of donor-specific pancreatic islet xenografts in fully xenogeneic chimeras (WF rat----B10 mouse).

We recently reported that reconstitution of lethally irradiated B10 mouse recipients with 40 x 10(6) untreated WF rat bone marrow cells resulted in stable fully xenogeneic chimerism (WF rat----B10 mouse). In these animals, the tolerance induced for skin xenografts was highly MHC specific in that donor-specific WF rat skin grafts were significantly prolonged while MHC-disparate third-party xenografts were rapidly rejected (median survival time [MST] = 9 days). We have now examined whether islet cell xenografts placed under the renal capsule of chimeras rendered diabetic with streptozotocin would be accepted and remain functional to maintain euglycemia. Animals were prepared, typed for chimerism at 6 weeks, and diabetes induced with streptozotocin. Donor-specific WF (Rt1Au) islet cell xenografts were significantly prolonged (MST greater than 180 days) in WF----B10 chimeras, while MHC-disparate third-party F344 rat (Rt1A1) grafts were rejected with a time course similar to unmanipulated B10 mice (MST = 8 days). The transplanted donor-specific islet cells were functional to maintain euglycemia, since removal of the grafts at from 100 to 180 days in selected individual chimeras uniformly resulted in return of the diabetic state. These data suggest that donor-specific islet cell xenografts are accepted and remain functional in mice rendered tolerant to rat xenoantigens following bone marrow transplantation.

Animals↗
PubMed1992

Hepatic artery pseudoaneurysm ligation after orthotopic liver transplantation--a report of 7 cases.

Pseudoaneurysm (PA) is a rare but life-threatening complication of liver transplantation. The authors present their experience on 7 patients treated by ligation of a post-OLT PA. Hepatic artery ligation or embolization was performed from 10 to 70 days after liver transplantation. Of the seven patients, four survived, one developed a biliary stricture, treated by percutaneous balloon dilatation, two died of a complication not related to treatment, and one died of multiple organ failure.

Adult↗