Local density of states on a vibrational quantum dot out of equilibrium

We calculate the nonequilibrium local density of states on a vibrational quantum dot coupled to two electrodes at T=0 using a numerically exact diagrammatic Monte Carlo method. Our focus is on the interplay between the electron-phonon interaction strength and the bias voltage. We find that the spectral density exhibits a significant voltage dependence if the voltage window includes one or more phonon sidebands. A comparison with well-established approximate approaches indicates that this effect could be attributed to the nonequilibrium distribution of the phonons. Moreover, we discuss the long transient dynamics caused by the electron-phonon coupling.Comment: 9 pages, 11 figure

Long transient dynamics in the Anderson-Holstein model out of equilibrium

We calculate the time dependent nonequilibrium current through a single level quantum dot strongly coupled to a vibrational mode. The nonequilibrium real time dynamics caused by an instantaneous coupling of the leads to the quantum dot is discussed using an approximate method. The approach, which is specially designed for the strong polaronic regime, is based on the so-called polaron tunneling approximation. Considering different initial dot occupations, we show that a common steady state is reached after times much larger than the typical electron tunneling times due to a polaron blocking effect in the dot charge. A direct comparison is made with numerically exact data, showing good agreement for the time scales accessible by the diagrammatic Monte Carlo simulation method

VITA-D: Cholecalciferol substitution in vitamin D deficient kidney transplant recipients: A randomized, placebo-controlled study to evaluate the post-transplant outcome

<p>Abstract</p> <p>Background</p> <p>Vitamin D does not only regulate calcium homeostasis but also plays an important role as an immune modulator. It influences the immune system through the induction of immune shifts and regulatory cells resulting in immunologic tolerance. As such, vitamin D is thought to exert beneficial effects within the transplant setting, especially in kidney transplant recipients, considering the high prevalence of vitamin D deficiency in kidney transplant recipients.</p> <p>Methods/Design</p> <p>The VITA-D study, a randomized, placebo-controlled, double-blind study with two parallel groups including a total of 200 kidney transplant recipients, is designed to investigate the immunomodulatory and renoprotective effects of cholecalciferol (vitamin D₃) within the transplant setting. Kidney transplant recipients found to have vitamin D deficiency defined as 25-hydroxyvitamin D₃< 50 nmol per liter will be randomly assigned to receive either oral cholecalciferol therapy or placebo and will be followed for one year. Cholecalciferol will be administered at a dose of 6800 International Units daily over a time period of one year.</p> <p>The objective is to evaluate the influence of vitamin D₃substitution in vitamin D deficient kidney transplant recipients on the post-transplant outcome. As a primary endpoint glomerular filtration rate calculated with the MDRD formula (modification of diet in renal disease) one year after kidney transplantation will be evaluated. Incidence of acute rejection episodes, and the number and severity of infections (analyzed by means of C-reactive protein) within the first year after transplantation will be monitored as well. As a secondary endpoint the influence of vitamin D₃on bone mineral density within the first year post-transplant will be assessed. Three DXA analyses will be performed, one within the first four weeks post-transplant, one five months and one twelve months after kidney transplantation.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov NCT00752401</p

The effect of steroid pretreatment of deceased organ donors on liver allograft function: A blinded randomized placebo-controlled trial

BACKGROUND & AIMS: Brain death-associated inflammatory response contributes to increased risk of impaired early liver allograft function, which might be counterbalanced by steroid pretreatment of the organ donor. The aim of this randomized controlled trial was to elucidate whether steroid pretreatment of liver donors improves early liver allograft function, prevents rejection and prolongs survival. METHODS: A placebo-controlled blinded randomized clinical trial was performed in three different centers in Austria and Hungary between 2006 and 2008. Ninety deceased organ donors received either 1000 mg of methylprednisolone or placebo 6h before recovery of organs. The primary end point was the concentration slope of transaminases within the first week. The secondary end point included survival and biopsy-confirmed acute rejection (BCAR) within 3 years after transplantation. RESULTS: Of the 90 randomized donors, 83 recipients were eligible for study. The trajectories of ALT and AST were not different between treatments (p=0.40 and p=0.13, respectively). Eight subjects died in the steroid and 13 in the placebo group within 3 years after engraftment (RR=0.63 95% CI [0.29,1.36], p=0.31). Eleven recipients experienced biopsy-confirmed rejection (BCAR) in the steroid and 11 in the placebo group (RR=1.02 95% CI [0.50,2.10], p=1.00). No effect modification could be identified in the predefined strata of donor age, sex, cold ischemic time, and cause of donor death. CONCLUSIONS: Steroid pretreatment of organ donors did not improve outcomes after liver transplantation

Efficacy and safety of tacrolimus compared with ciclosporin-A in renal transplantation: 7-year observational results

The European Tacrolimus versus Ciclosporin-A Microemulsion (CsA-ME) Renal Transplantation Study demonstrated that tacrolimus decreased acute rejection rates at 6 months. Primary endpoints of this investigator-initiated, observational 7-year follow-up study were acute rejection rates, patient and graft survival rates, and a composite endpoint (BPAR, graft loss, and patient death). We analyzed data from the original intent-to-treat population (n = 557; 286 tacrolimus, 271 CsA-ME). A total of 237 tacrolimus and 208 CsA-ME patients provided data. At 7 years, Kaplan-Meier estimated rates of patients free from BPAR were 77.1% in the tacrolimus arm and 59.9% in the CsA-ME arm, graft survival rates amounted to 82.6% and 80.6%, and patient survival rates to 89.9% and 88.1%. Estimated combined endpoint-free survival rates were 60.2% in the tacrolimus arm and 47.0% in the CsA-ME arm (P = <0.0001). A higher number of patients from the CsA-ME arm crossed over to tacrolimus during 7 year follow-up: 19.7% vs. 7.9% (P = <0.002). More patients in the tacrolimus group stopped steroids and received immunosuppressive monotherapy. Significantly, more CsA-ME patients received lipid-lowering medication and experienced cosmetic and cardiovascular adverse events. Tacrolimus-treated renal transplant recipients had significantly higher combined endpoint-free survival rates mainly driven by lower acute rejection rates despite less immunosuppressive medication at 7 years