TRPM3 channels provide a regulated influx pathway for zinc in pancreatic beta cells

Zinc is stored in insulin-containing dense core vesicles of pancreatic β-cells where it forms crystals together with insulin and calcium ions. Zinc ions are therefore released together with insulin upon exocytosis of these vesicles. Consequently, pancreatic β-cells need to take up large amounts of zinc from the extracellular space across their plasma membrane. The pathways for zinc uptake are only partially understood. TRPM3 channels are present in pancreatic β-cells and can be activated by the endogenous steroid pregnenolone sulfate. We demonstrate here that recombinant TRPM3 channels are highly permeable for many divalent cations, in particular also for zinc ions. Importantly, TRPM3 channels endogenously expressed in pancreatic β-cells are also highly permeable for zinc ions. Using FluoZin3 to image changes of the intracellular zinc concentration, we show that pancreatic β-cells take up zinc through TRPM3 channels even when extracellular zinc concentrations are low and physiological levels of calcium and magnesium are present. Activation of TRPM3 channels also leads to depolarization of β-cells and to additional zinc influx through voltage-gated calcium channels. Our data establish that TRPM3 channels constitute a regulated entry pathway for zinc ions in pancreatic β-cells.     

Immunogenicity and safety of a measles-mumps-rubella-varicella vaccine following a 4-week or a 12-month interval between two doses

Background

The MMRV combination vaccine, Priorix-Tetra™, is currently licensed in several European countries using a two-dose schedule in infants aged ≥9 months, with a preferred 6-week to 3-month interval between doses. This study was undertaken to generate safety and immunogenicity data for two doses of MMRV vaccine administered according to dose schedules using the shortest permitted interval of 4 weeks versus a longer interval of 12 months, which would allow flexible adaptation to local immunization calendars.

Methods

Healthy children aged 11-13 months were randomized (1:1:1) to receive 2 doses of either: MMRV vaccine with a 4-week interval between doses (MMRV-4W group, N = 188), MMRV vaccine with a 12-month interval between doses (MMRV-12M group, N = 184), or MMR vaccine with a 4-week interval between doses (MMR group, N = 187). Blood samples were taken prior to, and 4-6 weeks after each vaccination.

Results

Post-Dose 2, both MMRV groups exhibited an adequate immunogenic response for all components; however the MMRV-12M group showed significantly greater geometric mean titers for mumps, rubella and varicella. Two varicella breakthrough cases occurred within the 12-month interval between doses in the MMRV-12M group. Local and general reactogenicity results were similar for all groups except for the MMRV-4W group, which had a greater incidence of fever during Days 0-14 post-Dose 1.

Conclusions

Two doses of MMRV vaccine administered in the second year of life elicited adequate immunogenicity and were well-tolerated whether administered with a dose interval of 4 weeks or 12 months.     

Red blood cell transfusion in patients with subarachnoid hemorrhage: a multidisciplinary North American survey

Introduction  

Anemia is associated with poor outcomes in patients with aneurysmal subarachnoid hemorrhage (SAH). It remains unclear whether this association can be modified with more aggressive use of red blood cell (RBC) transfusions. The degree to which restrictive thresholds have been adopted in neurocritical care patients remains unknown.     

Cortical spreading ischemia in the absence of proximal vasospasm after aneurysmal subarachnoid hemorrhage: evidence for a dual mechanism of delayed cerebral ischemia

There are longstanding inconsistencies in the evidence thought to link vasospasm in the major branches of the Circle of Willis with delayed cerebral ischemia and poor outcome from aneurysmal subarachnoid hemorrhage (aSAH). The demonstrations, first in the laboratory, and more recently in patients with aSAH, of cortical spreading ischemia based on an abnormal response of the cerebral microcirculation to spreading depolarization offer an additional possible mechanism for delayed ischemia. That such events can occur in the substantial absence of proximal vasospasm is compatible with this concept, but the preliminary evidence needs support from more extensive studies.     

Capture of magnetic carriers within large arteries using external magnetic fields

Our overall research goal is to advance the safety and effectiveness of acute ischemic stroke therapy by improving the benefit/risk ratio of thrombolysis and hence, the long-term outcome of acute ischemic stroke victims. Our approach is the development of a novel tissue plasminogen activator (t-PA) delivery system based on t-PA-loaded magnetic nano- and microcarriers guided directly to the site of vascular occlusion by external magnetic fields. Such a t-PA delivery system would conveniently combine the advantages of both intravenous (systemic) and intraarterial (catheter-facilitated) thrombolysis: non-invasiveness - the magnetic t-PA carriers can be injected intravenously and targeted, as drug delivery is magnetically guided to and t-PA focally released at and within the vascular clot to induce lysis. The focus of our discussion are the two necessary, fundamental and interrelated bioengineering steps: the research and development of well-characterized, biocompatible, functionally active and t-PA-loaded (encapsulated) magnetic nano- and microcarriers able to induce effective thrombolysis, and the design of magnetic guidance systems for targeted tPA-delivery allowing also the triggered release of the thrombolytic agent at the clot site. In this paper, we theoretically demonstrated magnetic trapping of blood borne magnetic nano- and microcarriers from human large vessels, especially arteries. Then, some preliminary experiments using primate models (monkeys) were done to identify successful in vivo sequestration of magnetic carriers in large and smaller arterial branches after arterial upstream and systemic venous injection. Histology (hematoxylin-eosin stain) verified intraarterial carrier concentration (identified as black carrier agglomerates on H and E staining) at the arterial region above the surface magnet. The results revealed the feasibility of magnetic drug-targeting at arteries and solidified the proposed t-PA delivery system.     

Uncoupling of endothelial nitric oxide synthase after experimental subarachnoid hemorrhage

We studied whether endothelial nitric oxide synthase (eNOS) is upregulated and uncoupled in large cerebral arteries after subarachnoid hemorrhage (SAH) and also whether this causes cerebral vasospasm in a mouse model of anterior circulation SAH. Control animals underwent injection of saline instead of blood (n=16 SAH and n=16 controls). There was significant vasospasm of the middle cerebral artery 2 days after SAH (lumen radius/wall thickness ratio 4.3±1.3 for SAH, 23.2±2.1 for saline, P<0.001). Subarachnoid hemorrhage was associated with terminal deoxynucleotidyl transferase dUTP nick-end labeling, cleaved caspase-3, and Fluoro-Jade-positive neurons in the cortex and with CA1 and dentate regions in the hippocampus. There were multiple fibrinogen-positive microthromboemboli in the cortex and hippocampus after SAH. Transgenic mice expressing lacZ under control of the eNOS promoter had increased X-gal staining in large arteries after SAH, and this was confirmed by the increased eNOS protein on western blotting. Evidence that eNOS was uncoupled was found in that nitric oxide availability was decreased, and superoxide and peroxynitrite concentrations were increased in the brains of mice with SAH. This study suggests that artery constriction by SAH upregulates eNOS but that it is uncoupled and produces peroxynitrite that may generate microemboli that travel distally and contribute to brain injury.     

Lower incidence of cerebral infarction correlates with improved functional outcome after aneurysmal subarachnoid hemorrhage

Despite an undisputed association between vasospasm and delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage (SAH), there is debate if this association implies causality. It has been suggested that cerebral infarction is a better outcome measure than vasospasm in clinical trials and observational studies. To further investigate the relationship between infarction and outcome, we performed a systematic review and meta-analysis of all randomized, double-blind, placebo-controlled trials that studied the efficacy of pharmaceutical preventive strategies in SAH patients, and had both cerebral infarction and clinical outcome as outcome events. Effect sizes were expressed in (pooled) risk ratio (RR) estimates with corresponding 95% confidence intervals (CIs). Sensitivity analyses were performed for studies with a low risk of bias and for those who reported outcome at 3 months after SAH. Twenty-four studies including 8,552 patients were included. Pharmaceutical treatments decreased the incidence of both cerebral infarction (RR: 0.83; 95% CI: 0.74 to 0.93) and of poor functional outcome (RR: 0.92; 95% CI: 0.86 to 0.98). The sensitivity analyses did not change the results essentially. These data suggest that the previously observed association between cerebral infarction and functional outcome implies causality, and that cerebral infarction is a better outcome measure than vasospasm in clinical trials and observational studies.     

The psychosis continuum in the general population: findings from the São Paulo Epidemiologic Catchment Area Study

The aim of the study was to examine the psychosis continuum in a Latin-American community setting. Data were from the Brazilian São Paulo Epidemiologic Catchment Area Study, a cross-sectional survey conducted in two boroughs of the city of São Paulo. The Composite International Diagnosis Interview (version 1.1) was applied to a probabilistic sample of 1,464 adults, who were interviewed in their household, in order to identify the presence of psychotic symptoms. A subsample was assessed with Schedules for Clinical Assessment in Neuropsychiatry interview. We described the occurrence of psychotic symptoms, categorized into subgroups according to their clinical impact, disability, and help-seeking behavior. The correlation of socio-demographic variables, depressive symptoms, and alcohol and substance use disorders with those psychotic subgroups was analyzed. Polychotomic logistic regression tested the associations between subgroups of psychosis (clinical and subclinical) and the correlates. Of the total sample, 38.0% presented at least one lifetime psychotic symptom, 1.9% met the criteria for an ICD-10 diagnosis of non-affective psychosis, 5.4% presented clinically relevant psychotic symptoms, and 30.7% endorsed clinically non-relevant symptoms. The most common psychotic symptom was delusion with a plausible explanation (in 18.6%). The presence of any psychiatric diagnosis was associated with the presence of psychotic symptoms (OR range, 1.9–8.9). Subclinical psychosis subgroups were found to be associated with the 18–24 year age bracket, chronic depressive mood, and alcohol use disorder. Our results support the concept of a psychosis continuum in Latin-American populations, suggesting that different risk factors influence their manifestation across the continuum.