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Biomedical subjects

P Atkison

Publications and source records attributed to P Atkison.

At least 19 recordsLinked to original sources
PubMed2004

Studies of Pediatric Liver Transplantation 2002: patient and graft survival and rejection in pediatric recipients of a first liver transplant in the United States and Canada.

Studies of Pediatric Liver Transplantation (SPLIT) is a cooperative research network comprising 38 pediatric liver transplant centers in North America. Data from the 1092 patients who have received a first liver transplant since 1995 were analyzed for factors influencing patient survival, graft survival and acute rejection. The 3, 12, 24 and 36 month Kaplan-Meier estimates of patient/graft survival were 90.9/85.5, 86.3/80.2, 84.3/76.0, and 83.8/75.3% respectively. Univariate analysis identified initial diagnosis, type of graft (whole vs. living and cadaveric technical variant), growth failure and continuous hospitalization or ICU admission prior to transplantation as significantly influencing patient and graft survival. Subsequent multivariate analysis identified as risk factors for death: fulminant liver failure (RR = 3.05, p < 0.05), cadaveric technical variant grafts (RR = 1.95, p < 0.05), continuous hospitalization pre-transplant (RR = 1.79, p < 0.05), height deficit >2 s.d. from mean (RR = 3.22, p < 0.05). Risk factors for graft loss included: fulminant liver failure (RR = 2.27, p < 0.05), cadaveric technical variant grafts, (RR = 1.97, p < 0.05). Eleven percent of the 1092 patients were re-transplanted; vascular complications, particularly hepatic artery thrombosis (8.3% overall; 36.3% of graft failures), were responsible for the majority of re-transplants. Infection was the single most important cause of death (40 of 141, 28.4%) and was a contributing cause in 55 (39%), particularly with bacterial or fungal organisms. The cumulative Kaplan-Meier estimates of first rejection at 3, 12, 24 and 36 months were 44.8, 52.9, 59.1, and 60.3%. Initial immunosuppression with tacrolimus reduced the probability of rejection (RR = 0.62, p < 0.05). Eleven percent of rejections were steroid-resistant; chronic rejection led to 7 of 121 (5.8%) re-transplants. The SPLIT registry, in compiling data from a large number of centers, reflects the current outcomes for pediatric liver transplants in North America.

Adolescent↗
PubMed1998

Glucose turnover and insulin sensitivity in rats with pancreatic islet transplants.

To study the metabolic effects of insulin derived from islet grafts, oral glucose tolerance (OGT) and glucose turnover were examined in streptozotocin-induced diabetic Lewis rats rendered normoglycemic by syngeneic islet grafts in the renal subcapsular space (REN), in REN with renal vein-to-mesenteric vein anastomosis (REN-RMA), in the liver (intrahepatic [IH]), or in a parahepatic omental pouch (POP) and compared with normal rats. Normal OGT was found at 1 month posttransplant in all animals receiving approximately 3,000 islets, with hyperinsulinemic responses in the REN group compared with the other groups, and with higher C-peptide responses in the IH group than in the other groups (P < 0.05 by one-way analysis of variance). Glucose turnover studies in the insulin-stimulated steady state (INS-SS; infusion of insulin at 10 pmol x kg(-1) x min(-1)) at 2 months posttransplant showed that whole body glucose disappearance rates (Rd) were similar in all groups, but the REN group had higher steady-state insulin levels than the other groups. Glucose infusion rates (GIRs) were lower in the REN and IH groups than in the other groups. Apparent endogenous glucose production (EGP) was not completely inhibited in the REN and IH groups, while complete inhibition was observed in the other groups. When INS-SS insulin levels were matched to the level in REN rats by increasing the insulin infusion rate to 20 pmol x kg(-1) x min(-1) in REN-RMA, IH, and normal rats, GIR and Rd were elevated, exceeding those values in REN rats, but GIR in IH rats was still lower than in REN-RMA and normal rats. Thus, 1) in the REN group, impairment of inhibition of EGP and of stimulation of Rd by exogenous insulin contribute to insulin resistance; 2) in the IH group, incomplete inhibition of EGP is the major determinant of insulin resistance; and 3) with portal delivery of insulin in the REN-RMA and POP groups, normal insulin sensitivity is preserved. The present study confirms that hepatic portal delivery of islet secretions is necessary for physiological regulation of glucose metabolism. The study also suggests the IH grafts do not provide physiological regulation of glucose metabolism, raising the question of whether the liver is an appropriate site for insulin-secreting tissue replacement therapy in diabetes.

Anastomosis, Surgical↗
PubMed1997

Small bowel transplantation in children.

Small bowel transplantation has become a life-saving procedure for selected adults and children with intestinal failure who are intolerant to parental nutrition. There are few pediatric data available on the results of this procedure. In this article we review the background of intestinal transplantation, present the results from the University of Western Ontario in London, Ontario and the University of Miami in Miami, Florida, and discuss some future directions. The majority of successful transplants are fully functional, and these children are able to assume a normal diet.

Child↗
PubMed1996

Small bowel transplantation. A life-saving option for selected patients with intestinal failure.

Thirty-seven patients were listed for small bowel transplantation; 16 were transplanted and 15 died while waiting for a donor. Cyclosporine (N = 6) or tacrolimus (N = 10) were used for immune suppression. Graft rejection rates were lower in the combined liver/small bowel grafts than the isolated intestinal transplants (1/7 vs 5/7; P < 0.01) All of the cyclosporine group have died; the median survival was 25.7 months with two patients living more than five years. The tacrolimus group had fewer infections and a shorter hospital stay. All but two are alive with a median survival of 13 months. Seven of eight long-term survivors are off intravenous feedings. We conclude that small bowel transplantation is a life-saving option for patients with intestinal failure who cannot be maintained on total parenteral nutrition.

Adolescent↗
PubMed1995

Hypertrophic cardiomyopathy associated with tacrolimus in paediatric transplant patients.

Reported side-effects of tacrolimus, a potent immunosuppressive agent, have not included cardiotoxicity. We describe 5 consecutive paediatric transplant recipients (3 small bowel with or without liver and 2 liver) who received tacrolimus. 2 developed congestive heart failure and hypertrophic obstructive cardiomyopathy which resolved after changing to cyclosporin. In the other 3 patients the cardiomyopathy regressed or improved with a lower dose of tacrolimus or after stopping the drug.

Blood Pressure↗
PubMed1992

Cyclosporin A treatment of young children with newly-diagnosed type 1 (insulin-dependent) diabetes mellitus. London Diabetes Study Group.

Several studies have demonstrated the efficacy of cyclosporin A in modifying the initial course of Type 1 (insulin-dependent) diabetes mellitus in older children and adults but none have reported the effects in very young children. We treated 14 newly-diagnosed Type 1 diabetic patients aged 22 months to 95 months with cyclosporin A. Mean insulin dose at entry was 0.7 +/- 0.07 IU.kg-1.day-1. Initial cyclosporin A dose was 10 mg.kg-1.day-1. Insulin dose reached a nadir of 0.13 IU.kg-1.day-1 by 180 days. Mean glucagon-stimulated connecting peptide levels were maximal at 6 months (0.75 nmol/l) and were maintained while on cyclosporin A. Insulin was discontinued in four patients for 4, 12, 15 and 30 months respectively. In five other patients the insulin dose was less than 0.15 IU.kg-1.day-1 for at least 3 months. Glycated haemoglobin levels for all patients were within the normal range. Side effects included anorexia, stomach pains, poor weight gain, hypertrichosis, gum hyperplasia, mild anaemia and elevated creatinine. All patients have now discontinued cyclosporin A and all but one have been followed for 5 years after discontinuation. Reasons for discontinuing cyclosporin A included exposure to chicken pox (varicella), non-resolving otitis media, incomplete or no response and relapse. All side effects have resolved since the treatment was discontinued. Following discontinuation of cyclosporin A insulin requirements and glycated hemoglobin levels increased while glucagon-stimulated connecting peptide levels declined dramatically.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1992

Histological and immunopathological analysis of recovered encapsulated allogeneic islets from transplanted diabetic BB/W rats.

Allogeneic islets encapsulated in an alginate/poly-L-lysine membrane and transplanted into diabetic BB/W rats resulted in graft failure within 2 weeks of transplantation. Graft failure was associated with a dense pericapsular infiltrate (PCI) that resulted in necrosis of the encapsulated islets. The PCI could be inhibited by immunosuppressive agents, including cyclosporine and dexamethasone, and this resulted in a significant increase in graft survival. Immunopathological characterization of the PCI indicated that there was a predominance of macrophages. T helper cells also appeared to be present in this PCI. Empty capsules were also found to induce a similar PCI that was identical in composition to that found around encapsulated islets. Thus alginate/poly-L-lysine capsules do not appear to be biocompatible and may account for the variable results in islet graft survival found with these capsules.

Animals↗