influence.ME: tools for detecting influential data in mixed effects models

influence.ME provides tools for detecting influential data in mixed effects models. The application of these models has become common practice, but the development of diagnostic tools has lagged behind. influence.ME calculates standardized measures of influential data for the point estimates of generalized mixed effects models, such as DFBETAS, Cook’s distance, as well as percentile change and a test for changing levels of significance. influence.ME calculates these measures of influence while accounting for the nesting structure of the data. The package and measures of influential data\ud are introduced, a practical example is given, and strategies for dealing with influential data are suggested

Transplantation of the small intestine: the pathologist's perspective.

Small-bowel transplantation is now ready for clinical trials. The surgical techniques and methods for immunosuppression and monitoring bowel status have been developed in animal models over the past 30 years. Several attempts at small-bowel transplantation in humans have already been reported. In the course of future trials, pathologists will be involved in the monitoring of the posttransplant course by mucosal biopsies and functional studies, including maltose and xylose absorption tests. The morphology of rejection has been studied in canine and rat models. Activated lymphocytes and plasma cells infiltrate the lamina propria and invade crypt epithelium, causing "cryptitis." Villous blunting ensues, resulting eventually in necrosis. Graft survival without immunosuppression is about 10 days. Under Cyclosporine immunosuppression, a lymphoplasmacytic infiltrate has been noted around nerves and vessels in the submucosa. The overlying mucosa may be relatively normal. End-stage bowel is characterized by a contracted, scarred mass. Due to the large amount of lymphoid tissue in the allograft, graft-versus-host disease is a significant problem in small-bowel transplantation

Small bowel and liver/small bowel transplantation in children.

A clinical trial of intestinal transplantation was initiated at the University of Pittsburgh in May 1990. Eleven children received either a combined liver/small bowel graft (n = 8) or an isolated small bowel graft (n = 3). Induction as well as maintenance immunosuppression was with FK-506 and steroids. Four patients were male, and seven were female; the age range was 6 months to 10.2 years. There were 3 deaths (all in recipients of the combined liver/small bowel graft), which were attributed to graft-versus-host disease (n = 1), posttransplant lymphoproliferative disease (n = 1), and biliary leak (n = 1). Transplantation of the intestine has evolved into a feasible operation, with an overall patient and graft survival rate of 73%. These survivors are free of total parenteral nutrition, and the majority are home. These encouraging results justify further clinical trials

Percutaneous transhepatic cholangiography and biliary drainage after liver transplantation: A five-year experience

Evaluation of the biliary tract by percutaneous transhepatic cholangiography (PTC) is often required in liver transplant patients with an abnormal postoperative course. Indications for PTC include failure of liver enzyme levels to return to normal postoperatively, an elevation of serum bilirubin or liver enzyme levels, suspected bile leak, biliary obstructive symptoms, cholangitis, and sepsis. Over a 5-year period 625 liver transplants in 477 patients were performed at the University Health Center of Pittsburgh. Fifty-three patients (56 transplants) underwent 70 PTCs. Complications diagnosed by PTC included biliary strictures, bile leaks, bilomas, liver abscesses, stones, and problems associated with internal biliary stents. Thirty-two percutaneous transhepatic biliary drainage procedures were performed. Ten transplantation patients underwent balloon dilatation of postoperative biliary strictures. Interventional radiologic techniques were important in treating other complications and avoiding additional surgery in many of these patients. © 1987 Springer-Verlag New York Inc

Role of splenectomy in human liver transplantation under modern-day immunosuppression

Between January 1987 and October 1991, 1466 patients underwent consecutive Orthotopic Liver Transplantation (OLTx) at the University of Pittsburgh. Forty of these patient's had concomitant splenectomy with OLTx. These patients were compared to 147 randomly selected OLTx patients without splenectomy within the same time period. One-year patient and graft survival (PS and GS) were lower in splenectomized (Splx) patients compared to nonsplenectomized (non-Splx) patients (59% vs 86% PS, 55% vs 80% GS, respectively). One-month and one-year patient mortality in the Splx group was higher than in the non-splx patients (20% vs 3.4% P < 0.001 for one month; 40% vs 14.3%, P = 0.003 for one year, respectively). One-month and one-year sepsis-related mortality was also high in Splx patients (17.5% vs 2.7%, P = 0.0022, for one month, and 30% vs 11.5%, P = 0.0043, for one year, respectively). We conclude that concomitant splenectomy with OLTx has a significantly higher patient mortality mainly due to its septic complications and, at present, unless there is a specific indication for a splenectomy, the routine addition of this procedure to liver allograft surgery would not be recommended

Nonobstructing Colonic Dilatation and Colon Perforations Following Renal Transplantation

Nonobstructing colonic dilatation has not been commonly reported following renal transplantation, and colon perforations carry a high morbidity and mortality in this population. During a 7-year period, nonobstructing colonic dilatation developed in 13 adults 1 to 13 days after renal transplantation. Twelve (92%) of the 13 had poorly functioning allografts. Five (83%) of the 6 with and 2 (29%) of the 7 without colonoscopy had resolution of nonobstructing colonic dilatation. Of the seven right-sided colon perforations during this period, six were associated with nonobstructing colonic dilatation. An additional 4 patients had diverticular perforations in the left colon. Of a total of 11 patients with colon perforation, 7 had surgery within 24 hours of the perforation and 6 (86%) of these survived. Only 1 (25%) of the 4 having surgery more than 24 hours later survived. Six of the survivors retained functioning allografts. Nonobstructing colonic dilatation seems to be a potential complication of poor graft function after renal transplantation, and colonoscopy is effective in its treatment. In patients with colon perforations, early surgery and reduced immunosuppression are essential in decreasing mortality. © 1990, American Medical Association. All rights reserved