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Background and Aims The reliability of haemoglobin A1c (HbA1c) as a glycaemic marker in patients receiving haemodialysis (HD) remains unknown. To assess accuracy, we compared HbA1c and fructosamine levels with interstitial glucose levels measured by continuous glucose monitoring (CGM) in patients with type 2 diabetes receiving HD. Method The HD group (maintenance HD and type 2 diabetes) comprised 30 patients who completed the study period of 17 weeks; the control group (type 2 diabetes and an estimated glomerular filtration rate >60 mL/min/1.73 m2) comprised 36 individuals. CGM (Ipro2®, Medtronic) for periods up to seven days was performed five times (with four weeks intervals) during a 16-week period. HbA1c and fructosamine were measured at week 17. The mean sensor glucose from CGM was compared with the measured HbA1c, its estimated mean blood glucose (eMBGA1c) and fructosamine levels. Results In the HD group, the mean sensor glucose from CGM was 1.4 (95% confidence interval [CI]: 1.0–1.8) mmol/L higher than the eMBGA1c, whereas the difference was 0.1 mmol/L (95% CI: -0.1–[0.4]; P Conclusion HbA1c evaluated by CGM underestimates mean blood glucose levels in patients receiving maintenance HD; fructosamine appears to be more accurate. CGM-assessed blood glucose could complement or replace HbA1c in patients where HbA1c underestimates blood glucose levels.

Plants, as sessile organisms, gained the ability to sense and respond to biotic and abiotic stressors to survive severe changes in their environments. The change in our climate comes with extreme dry periods but also episodes of flooding. The latter stress condition causes anaerobiosis-triggered cytosolic acidosis and impairs plant function. The molecular mechanism that enables plant cells to sense acidity and convey this signal via membrane depolarization was previously unknown. Here, we show that acidosis-induced anion efflux from Arabidopsis (Arabidopsis thaliana) roots is dependent on the S-type anion channel AtSLAH3. Heterologous expression of SLAH3 in Xenopus oocytes revealed that the anion channel is directly activated by a small, physiological drop in cytosolic pH. Acidosis-triggered activation of SLAH3 is mediated by protonation of histidine 330 and 454. Super-resolution microscopy analysis showed that the increase in cellular proton concentration switches SLAH3 from an electrically silent channel dimer into its active monomeric form. Our results show that, upon acidification, protons directly switch SLAH3 to its open configuration, bypassing kinase-dependent activation. Moreover, under flooding conditions, the stress response of Arabidopsis wild-type (WT) plants was significantly higher compared to SLAH3 loss-of-function mutants. Our genetic evidence of SLAH3 pH sensor function may guide the development of crop varieties with improved stress tolerance.

PURPOSE: Direct ophthalmoscopy can reveal systemic, neurologic and ophthalmic conditions, but is poorly mastered among young physicians. A theoretical test is needed to measure effect of educational interventions. We developed and gathered validity evidence for a multiple-choice questionnaire (MCQ)-based theoretical test in direct ophthalmoscopy.METHODS: The MCQ was developed by interviewing experts. Then, validity evidence was evaluated using Messick's validity framework. Content was ensured by inviting the experts to contribute in a Delphi-like process. Response process was ensured by piloting and by streamlining all instructions. Then, the test was taken by ophthalmologists and by medical students without experience in direct ophthalmoscopy. Results were used to evaluate internal structure (item quality analysis and internal consistency), relations to other variables (correlation of test scores to experience level) and consequences (establishment of pass-fail score and the consequences of its use).RESULTS: The first phase of the study yielded 100 MCQs. In second phase, we identified that 60 items fulfilled predefined relevance and item quality requirements. These items demonstrated very high internal consistency (Cronbach's alpha = 0.95), significantly discriminated medical students from specialists (p < 0.001, independent samples t-test) and the established pass-fail score of 50 (83%) correct answers resulted in no false positives (students passing) and no false negatives (specialists failing). A Decision study identified that sampling 15 items suffice for certification.CONCLUSION: We developed and validated an MCQ-based theoretical test in direct ophthalmoscopy that enables an evidence-based approach to measuring, evaluating and certifying the theoretical knowledge necessary for direct ophthalmoscopy.

Tumors that invade the orbit are uncommon. The majority are meningiomas arising from the sphenoid ridge (66%). Others are bone and cartilage tumors arising from the surrounding bones of the orbit, pituitary adenomas, and epithelial tumors arising from the paranasal sinuses and nasal cavity. Meningiomas occur more often in women, whereas epithelial tumors have a predilection for men. Meningiomas and epithelial tumors typically present in the sixth decade of life, whereas bone tumors tend to affect individuals in their third decade of life. Patients often present with a combination of ophthalmological and otorhinolaryngological symptoms, including proptosis, pain, decreased visual acuity, restrictions in motility of the eye, epistaxis, and nasal obstruction. Sarcomas and benign bone and cartilage tumors arise from surrounding structures, whereas carcinomas usually arise from the paranasal sinuses. Surgery is the mainstay of treatment. Depending on the aggressiveness and histology of the tumor, surgery may be combined with radiation and chemotherapy. The prognosis is generally poor, but varies depending on histology and cell origin, size of the tumor, and degree of invasion. Meningiomas and benign bone tumors have the best prognoses. Sinonasal undifferentiated carcinomas, small-cell neuroendocrine carcinomas, osteosarcomas, and rhabdomyosarcomas have poorer prognoses.

Despite vast diversity in metabolites and the matching substrate specificity of their transporters, little is known about how evolution of transporter substrate specificities is linked to emergence of substrates via evolution of biosynthetic pathways. Transporter specificity towards the recently evolved glucosinolates characteristic of Brassicales is shown to evolve prior to emergence of glucosinolate biosynthesis. Furthermore, we show that glucosinolate transporters belonging to the ubiquitous NRT1/PTR FAMILY (NPF) likely evolved from transporters of the ancestral cyanogenic glucosides found across more than 2500 species outside of the Brassicales. Biochemical characterization of orthologs along the phylogenetic lineage from cassava to A. thaliana, suggests that alterations in the electrogenicity of the transporters accompanied changes in substrate specificity. Linking the evolutionary path of transporter substrate specificities to that of the biosynthetic pathways, exemplify how transporter substrate specificities originate and evolve as new biosynthesis pathways emerge. DOI: http://dx.doi.org/10.7554/eLife.19466.001, eLife digest All living cells are surrounded by membranes that protect them from the external environment. The membrane contains proteins called transporters, which move nutrients and other molecules (known as substrates) across the membrane. A variety of transporters have evolved to move the hundreds of thousands of different substrates found in nature. Plant cells make many different compounds to protect themselves from pests and diseases. A group of transporters known as the NPF family move some of these compounds across the cells outer membrane. The types of substrates they transport vary in different plants. In cassava, for example, NPF transporters move compounds called cyanogenic glucosides, which are poisonous to humans and other animals. On the other hand, NPF transporters in another plant called Arabidopsis thaliana can move bitter-tasting compounds called glucosinolates. The process that makes glucosinolates in plants evolved from the process that makes cyanogenic glucosides. Can transporters evolve the ability to move a new substrate before or after that substrate first appears? To answer this question, Jørgensen et al. studied the NPF family in A. thaliana, cassava and another plant called papaya that makes both cyanogenic glucosides and glucosinolates. The experiments suggest that NPF transporters able to move both cyanogenic glucosides and glucosinolates evolved before plants evolved the ability to make glucosinolates. Later in evolution, these multi-specific transporters specialized to only move glucosinolates. Jørgensen et al. also show that early glucosinolate transporters could move a broad variety of glucosinolates but later evolved to only transport particular types. These findings show how transporters and the processes that make compounds in cells may evolve together. A future challenge will be to understand the molecular changes in a transporter that make it specific for a certain substrate. This may help researchers to develop new ways of controlling the amount of toxic compounds in crops we eat by manipulating how the compounds are transported. DOI: http://dx.doi.org/10.7554/eLife.19466.002

Background. Patients with end-stage renal disease (ESRD) have glucometabolic disturbances resulting in a high prevalence of prediabetes. The underlying pathophysiology remains unclear, but may prove important for the strategies employed to prevent progression to overt diabetes. Meal-induced release of the insulinotropic gut-derived incretin hormones and pancreatic hormones play a critical role in the maintenance of a normal postprandial glucose tolerance. Methods. We studied patients with ESRD and either normal (n = 10) or impaired (n= 10) glucose tolerance, and control subjects (n = 11). Plasma concentrations of glucose, insulin, glucagon, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and paracetamol were measured repeatedly during a standardized 4-h liquid meal including 1.5 g paracetamol (added for evaluation of gastric emptying). Results. Fasting glucose and postprandial glucose responses were comparable between groups (P > 0.082). Patients with ESRD exhibited higher fasting levels of GIP and glucagon compared with controls (P < 0.001). Baseline-corrected GLP-1 and glucagon responses were enhanced (P < 0.002), baseline-corrected insulin responses and insulin excursions were reduced (P < 0.035), and paracetamol excursions were delayed (P < 0.024) in patients with ESRD compared with controls. None of the variables differed between the two ESRD subgroups. Conclusions. Non-diabetic patients with ESRD were characterized by reduced postprandial insulin responses despite increased secretion of the insulinotropic incretin hormone GLP-1. Fasting levels and baseline-corrected responses of glucagon were elevated and gastric emptying was delayed in the ESRD patients. These perturbations seem to be caused by uraemia per se and may contribute to the disturbed glucose metabolism in ESRD patients.

Oocytes of the African clawed frog, Xenopus laevis, are often used for expression and biochemical characterization of transporter proteins as the oocytes are particularly suitable for uptake assays and electrophysiological recordings. Assessment of the expression level of expressed transporters at the individual oocyte level is often desirable when comparing properties of wild type and mutant transporters. However, a large content of yolk platelets in the oocyte cytoplasm makes this a challenging task. Here we report a method for fast and easy, semiquantitative Western blot analysis of proteins heterologously expressed in Xenopus oocytes.

Introduction Diabetes is the leading cause of end-stage renal disease (ESRD). Owing to renal clearance, several antidiabetic agents cannot be used in patients with ESRD. The present protocol describes an investigator-initiated trial aiming to test safety and efficacy of treatment with the glucagon-like peptide-1 receptor agonist liraglutide in patients with type 2 diabetes and dialysis-dependent ESRD. Methods and analysis Twenty patients with type 2 diabetes and ESRD will be compared with 20 matched patients with type 2 diabetes and normal kidney function in a randomised, parallel, placebo-controlled (1 : 1), double-blinded setting. All participants will receive 12 weeks of daily treatment with liraglutide/placebo in an individually titrated dose of 0.6, 1.2 or 1.8 mg. Over nine visits, plasma liraglutide, glycaemic control, β-cell response, cardiovascular parameters, various biomarkers and adverse events will be assessed. The primary endpoint will be evaluated from dose-corrected plasma trough liraglutide concentration at the final trial visit to determine potential accumulation in the ESRD group. Ethics and dissemination The study has been approved by the Danish Medicines Agency, the Scientific-Ethical Committee of the Capital Region of Denmark and the Danish Data Protection Agency. An external monitoring committee (The Good Clinical Practice Unit at Copenhagen University Hospitals) will oversee the study. The results of the study will be presented at national and international scientific meetings, and publications will be submitted to peer-reviewed journals. Trial registration ClinicalTrials.gov Identifier: NCT01394341

Nondiabetic patients with end-stage renal disease (ESRD) have disturbed glucose metabolism, the underlying pathophysiology of which is unclear. To help elucidate this, we studied patients with ESRD and either normal or impaired glucose tolerance (10 each NGT or IGT, respectively) and 11 controls using an oral glucose tolerance test and an isoglycemic intravenous glucose infusion on separate days. Plasma glucose, insulin, glucagon, and incretin hormones were measured repeatedly, and gastrointestinal-mediated glucose disposal (GIGD) based on glucose amounts utilized, and incretin effect based on incremental insulin responses, were calculated. The GIGD was significantly reduced in both ESRD groups compared with controls. Incretin effects were 69% (controls), 55% (ESRD with NGT), and 41% (ESRD with IGT), with a significant difference between controls and ESRDs with IGT. Fasting concentrations of glucagon and incretin hormones were significantly increased in patients with ESRD. Glucagon suppression was significantly impaired in both groups with ESRD compared with controls, while the baseline-corrected incretin hormone responses were unaltered between groups. Thus, patients with ESRD had reduced GIGD, a diminished incretin effect in those with IGT, and severe fasting hyperglucagonemia that seemed irrepressible in response to glucose stimuli. These factors may contribute to disturbed glucose metabolism in ESRD.

1. Six healthy volunteers were given single oral doses of the antiemetic metopimazine (MPZ), starting with trial (a) 20 mg preprandially and followed by trial (b) 50 mg preprandially. In trials (c) and (d) the doses were similar to those in trials (a) and (b), but MPZ was given postprandially. To evaluate intra-individual variation in serum concentrations, trial (a) was repeated three times in four of the volunteers (trial (e)). 2. Blood samples were drawn and the serum concentrations of MPZ and its acid metabolite (AMPZ) were measured by h.p.l.c. 3. There was no evidence of dose-dependent kinetics at the dose levels studied. 4. Median AUC values were 22.6, 16.2, 52.4 and 35.2 (trials (a), (b), (c) and (d), ng ml-1 h). Food intake decreased the serum concentrations of MPZ, suggesting that MPZ should be taken preprandially.

The absorption of the antiemetic metopimazine (MPZ) given as a single dose of (a) 40 mg microenema, (b) 40 mg orally and (c) 10 mg as a 60 min i.v. continuous infusion was investigated in six healthy volunteers. Blood samples were drawn and the serum concentrations of MPZ and its acid metabolite were measured. The bioavailability of MPZ given orally and as enemas was 22.3 and 19.5% respectively. Partial avoidance of hepatic first pass metabolism was seen with the enemas, which in contrast to suppositories, seems to represent a reliable form of rectal administration.