Incidence and relative risk of renal replacement therapy in people with and without diabetes between 2002 and 2016 in a German region.

AIMS/HYPOTHESIS: Data on trends of end-stage renal disease among people with diabetes are lacking. We analysed the incidence of end-stage renal disease, defined as renal replacement therapy, among people with and without diabetes, and the corresponding relative risk. Moreover, we investigated time trends for the period 2002-2016. METHODS: In this retrospective population-based study we analysed data from one dialysis centre of a region in Germany covering a population of about 310,000 inhabitants. We estimated the age- and sex-standardised incidence rates for chronic renal replacement therapy among adults with and without diabetes and the corresponding relative risks. The time trend was analysed using Poisson regression models. RESULTS: Between 2002 and 2016, 1107 people (61.2% male; mean age 71.6 years; 48.7% with diabetes) had a first renal replacement therapy. During the study period, the incidence rate in the population with diabetes varied from 93.6 (95% CI 50.4, 136.7) in 2002 to 140.5 (95% CI 80.6, 200.4) in 2016 per 100,000 person-years. In the population without diabetes the incidence rate was substantially lower and reached 17.3 (95% CI 10.9, 23.6) in 2002 and 24.6 (95% CI 17.5, 31.7) in 2009. The relative risk comparing people with and without diabetes was 3.57 (95% CI 3.09, 4.13). No significant change in the incidence rates was found during the observation period, either in the population with or in the population without diabetes, and thus the relative risk also remained constant. CONCLUSIONS/INTERPRETATION: People with diabetes have a higher risk of needing renal replacement therapy than those without diabetes, a fact that remained constant over a time period of 15 years.

Atomic-level characterization of protein-protein association.

Despite the biological importance of protein-protein complexes, determining their structures and association mechanisms remains an outstanding challenge. Here, we report the results of atomic-level simulations in which we observed five protein-protein pairs repeatedly associate to, and dissociate from, their experimentally determined native complexes using a molecular dynamics (MD)-based sampling approach that does not make use of any prior structural information about the complexes. To study association mechanisms, we performed additional, conventional MD simulations, in which we observed numerous spontaneous association events. A shared feature of native association for these five structurally and functionally diverse protein systems was that if the proteins made contact far from the native interface, the native state was reached by dissociation and eventual reassociation near the native interface, rather than by extensive interfacial exploration while the proteins remained in contact. At the transition state (the conformational ensemble from which association to the native complex and dissociation are equally likely), the protein-protein interfaces were still highly hydrated, and no more than 20% of native contacts had formed.

Demonstrating an Order-of-Magnitude Sampling Enhancement in Molecular Dynamics Simulations of Complex Protein Systems.

Molecular dynamics (MD) simulations can describe protein motions in atomic detail, but transitions between protein conformational states sometimes take place on time scales that are infeasible or very expensive to reach by direct simulation. Enhanced sampling methods, the aim of which is to increase the sampling efficiency of MD simulations, have thus been extensively employed. The effectiveness of such methods when applied to complex biological systems like proteins, however, has been difficult to establish because even enhanced sampling simulations of such systems do not typically reach time scales at which convergence is extensive enough to reliably quantify sampling efficiency. Here, we obtain sufficiently converged simulations of three proteins to evaluate the performance of simulated tempering, a member of a widely used class of enhanced sampling methods that use elevated temperature to accelerate sampling. Simulated tempering simulations with individual lengths of up to 100 µs were compared to (previously published) conventional MD simulations with individual lengths of up to 1 ms. With two proteins, BPTI and ubiquitin, we evaluated the efficiency of sampling of conformational states near the native state, and for the third, the villin headpiece, we examined the rate of folding and unfolding. Our comparisons demonstrate that simulated tempering can consistently achieve a substantial sampling speedup of an order of magnitude or more relative to conventional MD.

Assessing the Accuracy of Two Enhanced Sampling Methods Using EGFR Kinase Transition Pathways: The Influence of Collective Variable Choice.

Structurally elucidating transition pathways between protein conformations gives deep mechanistic insight into protein behavior but is typically difficult. Unbiased molecular dynamics (MD) simulations provide one solution, but their computational expense is often prohibitive, motivating the development of enhanced sampling methods that accelerate conformational changes in a given direction, embodied in a collective variable. The accuracy of such methods is unclear for complex protein transitions, because obtaining unbiased MD data for comparison is difficult. Here, we use long-time scale, unbiased MD simulations of epidermal growth factor receptor kinase deactivation as a complex biological test case for two widely used methods-steered molecular dynamics (SMD) and the string method. We found that common collective variable choices, based on the root-mean-square deviation (RMSD) of the entire protein, prevented the methods from producing accurate paths, even in SMD simulations on the time scale of the unbiased transition. Using collective variables based on the RMSD of the region of the protein known to be important for the conformational change, however, enabled both methods to provide a more accurate description of the pathway in a fraction of the simulation time required to observe the unbiased transition.

Monthly continuous erythropoietin receptor activator treatment maintains stable hemoglobin levels in routine clinical management of hemodialysis patients.

Once-monthly administration of CERA, a continuous erythropoietin receptor activator, has shown equivalent efficacy to shorter-acting erythropoiesis-stimulating agents (ESAs) that require more frequent dosing, but data on routine use of once-monthly CERA in hemodialysis patients are lacking. Study on Efficacy, Safety and Applicability of Mircera (SESAM) was a prospective, multicenter, noninterventional trial with a duration of up to 9 months (month 0-5 "titration phase"; month 6-8 "evaluation phase") to test the stability of Hb control in hemodialysis patients under routine conditions. Patient selection, Hb targets and CERA dosing were at the discretion of the local nephrologist. 918 patients from 92 German nephrology centers were included. Ninety-three percent were on ESA treatment prior to study entry. The mean number of CERA dose changes during the study was 1.9 ± 1.9 per patient. Mean Hb level was 11.4 ± 1.2 g/dL at baseline and 11.7 ± 1.4 g/dL at the end of the 8-month study. During the evaluation phase (months 6-8), 15.6%, 40.3%, and 66.0% of patients had stable Hb (i.e., at least two values) in the ranges 11-12, 10-12, and 10-13 g/dL, respectively. The mean intra-individual fluctuation in Hb was 1.4 ± 0.7 g/dL during the study (0.5 ± 0.4 g/dL during the 3-month evaluation phase). More than 90% of patients, and > 80% of physicians, rated CERA therapy as "very good" or "good" throughout the study. Four patients (0.4%) discontinued prematurely due to adverse drug reactions. Once-monthly CERA therapy maintains stable Hb values with low intra-individual variability and few dose adaptations in hemodialysis patients when administered entirely according to local practice, and the regimen was well-tolerated.

High pre-eruptive water contents preserved in lunar melt inclusions.

The Moon has long been thought to be highly depleted in volatiles such as water, and indeed published direct measurements of water in lunar volcanic glasses have never exceeded 50 parts per million (ppm). Here, we report in situ measurements of water in lunar melt inclusions; these samples of primitive lunar magma, by virtue of being trapped within olivine crystals before volcanic eruption, did not experience posteruptive degassing. The lunar melt inclusions contain 615 to 1410 ppm water and high correlated amounts of fluorine (50 to 78 ppm), sulfur (612 to 877 ppm), and chlorine (1.5 to 3.0 ppm). These volatile contents are very similar to primitive terrestrial mid-ocean ridge basalts and indicate that some parts of the lunar interior contain as much water as Earth's upper mantle.

Pharmacokinetics of sulfobutylether-beta-cyclodextrin and voriconazole in patients with end-stage renal failure during treatment with two hemodialysis systems and hemodiafiltration.

Sulfobutylether-beta-cyclodextrin (SBECD), a large cyclic oligosaccharide that is used to solubilize voriconazole (VRC) for intravenous administration, is eliminated mainly by renal excretion. The pharmacokinetics of SBECD and voriconazole in patients undergoing extracorporeal renal replacement therapies are not well defined. We performed a three-period randomized crossover study of 15 patients with end-stage renal failure during 6-hour treatment with Genius dialysis, standard hemodialysis, or hemodiafiltration using a high-flux polysulfone membrane. At the start of renal replacement therapy, the patients received a single 2-h infusion of voriconazole (4 mg per kg of body weight) solubilized with SBECD. SBECD, voriconazole, and voriconazole-N-oxide concentrations were quantified in plasma and dialysate samples by high-performance liquid chromatography (HPLC) and by HPLC coupled to tandem mass spectrometry (LC-MS-MS) and analyzed by noncompartmental methods. Nonparametric repeated-measures analysis of variance (ANOVA) was used to analyze differences between treatment phases. SBECD and voriconazole recoveries in dialysate samples were 67% and 10% of the administered doses. SBECD concentrations declined with a half-life ranging from 2.6 +/- 0.6 h (Genius dialysis) to 2.4 +/- 0.9 h (hemodialysis) and 2.0 +/- 0.6 h (hemodiafiltration) (P < 0.01 for Genius dialysis versus hemodiafiltration). Prediction of steady-state conditions indicated that even with daily hemodialysis, SBECD will still exceed SBECD exposure of patients with normal renal function by a factor of 6.2. SBECD was effectively eliminated during 6 h of renal replacement therapy by all methods, using high-flux polysulfone membranes, whereas elimination of voriconazole was quantitatively insignificant. The SBECD half-life during renal replacement therapy was nearly normalized, but the average SBECD exposure during repeated administration is expected to be still increased.

Effectiveness and safety of recombinant human erythropoietin beta in maintaining common haemoglobin targets in routine clinical practice in Europe: the GAIN study.

OBJECTIVE: The Gain effectiveness in Anaemia treatment wIth NeoRecormon (epoetin beta) study (GAIN) evaluated the effectiveness and safety of recombinant human erythropoietin beta in correcting and/or maintaining common haemoglobin (Hb) targets in routine clinical practice in Europe. RESEARCH DESIGN AND METHODS: European 18-month observational, prospective clinical practice study across 217 centres from 13 countries. During a 3-month retrospective period, patients received any erythropoiesis stimulating agent (ESA). For the subsequent 18-month study phase, patients receiving intravenous (IV) epoetin beta or any other ESA were recommended to be switched to subcutaneous (SC) epoetin beta. Presence of anti-erythropoietin antibodies (AEAB) and related outcomes was investigated before and during the study. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov number: NCT00551603. MAIN OUTCOME MEASURES: Correction and maintenance of Hb levels within recommended target range and mean dose requirement to correct and maintain target Hb levels. RESULTS: A total of 4264 patients on haemodialysis received an ESA for treatment of renal anaemia. During the study period, the number of patients who maintained Hb levels in the recommended target range of 10-12 g/dL increased from 57% to 62%. Administration of SC epoetin beta resulted in a 24% lower mean dose requirement to maintain target Hb levels compared to IV administration (p < 0.001). Considerable differences were observed between countries in the study. No patients developed pure red cell aplasia associated with AEAB during observation. CONCLUSION: This observational study suggests that haemodialysis patients who are receiving any ESA via SC or IV administration for treatment of their renal anaemia can be safely and effectively switched to SC epoetin beta to achieve or maintain the currently recommended Hb targets. SC required a lower dose than IV administration to maintain similar efficacy, thereby potentially lowering the drug costs.