Quantum master equations from classical Lagrangians with two stochastic forces.

We show how a large family of master equations, describing quantum Brownian motion of a harmonic oscillator with translationally invariant damping, can be derived within a phenomenological approach, based on the assumption that an environment can be simulated by two classical stochastic forces. This family is determined by three time-dependent correlation functions (besides the frequency and damping coefficients), and it includes as special cases the known master equations, whose dissipative part is bilinear with respect to the operators of coordinate and momentum.

Effects of random migration in population dynamics.

We study the influence of random migration of a species (may be insects) in the population dynamics when initially all the individuals live in a primordial site (their habitats may be trees). We assume (i) a finite number of sites, (ii) that migration occurs randomly to nearest neighbors, and (iii) an on-site age-structured population whose size varies according to Ricker's map. We find that even for a very small migration rate, the population density becomes appreciably affected. If migration is not allowed, depending on the value of the characteristic parameters, the population may display a chaotic oscillation; however, with migration permitted, the chaos is reduced or even suppressed, and the population density will oscillate with period 2 or period 4. We examined the effects of migration through higher-order iterations of the map, entropy, and time correlation function. We also considered a long chain, analyzing (a) the spatial correlation between sites, noting the occurrence of a transition in the correlation function between sites separated by odd and even units of distance and (b) the fluctuations in time of the populations when initially all sites are populated.

Type II diabetes after combined kidney and pancreas transplantation for type I diabetes mellitus and end-stage renal disease.

We report a case of a patient who developed type II diabetes after receiving a successful combined kidney and pancreas transplant for type I diabetes and end-stage renal disease. This patient underwent a combined kidney and pancreas transplant and had no evidence of rejection with good function following the transplant for nine months. The patient developed significant post-transplant obesity with her transplant weight of 80 kg rising to 109 kg. At this level of obesity, the patient developed fasting hyperglycemia of 180 mg/dl with no change in her renal function or her pancreas exocrine function. She developed hyperinsulinemia to this fasting hyperglycemia. The clinical course of this patient demonstrates that rapid weight gain following transplantation can result in type II diabetes.

A facilitated technique for hepatectomy of porcine liver.

The swine liver has been used for experimental transplantation and as an ex vivo support system for patients with fulminant hepatic failure. Preservation of liver function after the cold storage period can be accomplished by complying with several key steps during the procurement: Keep the procedure short, provide extensive exposure, allow only minimal dissection, irrigate the portal system through the splenic vein and thereby obtain regular blood flow through the organ up to the clamping point, and ice the liver abruptly in situ. This retrieval technique was used and evaluated in 10 pigs. The method allowed a short and successful organ procurement while preserving normal function of the liver ex vivo.

Success and complications of pancreatic transplantation at one institution.

OBJECTIVE: The authors report the results and complications of the first 59 pancreas transplantation procedures performed at one institution. SUMMARY BACKGROUND DATA: Pancreas transplantation is performed at relatively few centers. Results have improved in the past few years. METHODS: A retrospective review was completed of the results and complications after pancreas transplantation at one institution. Pancreas transplantation was indicated for patients with insulin-dependent diabetes mellitus and who were younger than 50 years of age. The results were divided into era I (March 1987-December 1992) and era II (January 1993-October 1995). RESULTS: Fifty-nine transplants were performed since March 1987. There were 45 combined kidney/pancreas transplants and 13 pancreas transplants. Graft survival at 1 year was 57% for those in era I versus 79% in era II. Rejection occurred in 74% of the patients in era I and 48% in era II. Eighty-five percent of all rejection episodes in both eras were steroid resistant and required antibody therapy. Complications were not different from eras I and II. CONCLUSIONS: Pancreas transplantation is a successful procedure with a number of significant complications. Rejection episodes are most often steroid resistant.

Left gastric artery as an alternative for arterial reconstruction in orthotopic liver transplantation.

The hepatic arterial blood supply is indispensable for the survival of the graft during liver transplantation. Inadequacies in the recipient hepatic artery mandate arterial reconstruction different from the preferred method of direct anastomosis. We report the use of the left gastric artery as an attractive alternative for reconstructing the arterial blood supply of a transplanted liver.

Nodular regenerative hyperplasia: a controversial indication for orthotopic liver transplantation.

Nodular regenerative hyperplasia of the liver is an uncommon cause of portal hypertension. Patients with nodular regenerative hyperplasia have signs and symptoms of portal hypertension, without evidence of hepatocellular failure or encephalopathy. We report the case of a 44-year-old woman with recurrent esophageal bleeding and refractory ascites who had a history of hemosiderosis, hepatitis C, and chronic renal allograft rejection. Our preoperative diagnosis was cirrhotic end-stage liver disease and end-stage renal disease for which the patient underwent combined hepatic and renal transplantation. Her portal hypertension symptoms resolved, and her renal function has been normal for 18 months of follow-up. Histologic examination of the liver revealed nodular regenerative hyperplasia, and a review of the literature regarding the surgical management of patients with nodular regenerative hyperplasia revealed that various shunting procedures are generally recommended. After the failure of medical management in patients with nodular regenerative hyperplasia, portosystemic shunting may be indicated before proceeding to hepatic transplantation.