Astrocytic nitric oxide triggers tau hyperphosphorylation in hippocampal neurons

Production of nitric oxide (NO) by glial cells has been proposed to mediate cytotoxic effects on neighboring neurons. Although extensive genetic data implicate the beta amyloid peptide (Abeta) in the neurodegenerative cascade of Alzheimer's disease (AD), the molecular mechanisms underlying its effects on neurons and glia and the relationship between glial activation and neuronal death are not well understood. In AD, Abeta is sufficient to induce glial activation and promote the generation of inflammatory mediators including NO. We examined whether Abeta stimulated astrocytes to express nitric oxide synthase and produce NO. Also, we investigated whether astrocytic NO contributes to degenerative changes occurring in co-cocultured hippocampal neurons. We found that the treatment of rat hippocampal astrocyte cultures with Abeta(25-35) fragment up-regulated the mRNA and protein levels of both the inducible and neuronal forms of nitric oxide synthase (iNOS and nNOS, respectively) and increased the production of nitric oxide. Remarkably, hippocampal neurons co-cultured with astrocytes, previously stimulated with Abeta, displayed hyperphosphorylation of the microtubule-associated protein tau. This effect was attenuated by iNOS inhibitors, suggesting the role of overproduction of NO by reactive astrocytes in AD pathogenesis.     

Clinical Management of Small-Cell Carcinoma of the Urinary Tract: A 10-Year Single-Center's Experience

BackgroundSmall-cell carcinoma (SCC) comprises 1% of primary bladder tumors and approximately 2% of prostate neoplasms. Metastatic disease at diagnosis is common, and survival outcomes are extremely poor. There is controversy about the ideal clinical management of these patients. The neuron-specific enolase (NSE) serum levels have never been studied in patients with small-cell carcinoma of the urinary tract (SCCUT).Patients and MethodsWe report the clinical outcome of 12 consecutive SCCUT patients treated during the past 10 years. We also study the NSE levels at diagnosis and during treatment.ResultsPatients with limited disease (LD) experienced a non-significant longer progression-free survival (PFS) and overall survival (OS) compared with extensive disease (ED) subjects. Patients with bladder SCC showed a significantly higher median PFS compared with prostate SCCUT patients (22 vs. 6 months; P = .034), although that difference did not impact on a significant longer OS. NSE levels decreased during chemotherapy administration in all patients with ED and baseline high levels.ConclusionsOur patients showed a poor prognosis as described in previous studies. A better outcome for patients with bladder SCC compared with prostate SCC could be suggested. Serum NSE levels should be further evaluated to prove its potential use in early diagnosis and treatment monitoring during chemotherapy.     

Middle School Effects of the Dating Matters® Comprehensive Teen Dating Violence Prevention Model on Physical Violence,Bullying, and Cyberbullying: a Cluster-Randomized Controlled Trial

Few comprehensive primary prevention approaches for youth have been evaluated for effects on multiple types of violence. Dating Matters®: Strategies to Promote Healthy Teen Relationships (Dating Matters) is a comprehensive teen dating violence (TDV) prevention model designed by the Centers for Disease Control and Prevention and evaluated using a longitudinal stratified cluster-randomized controlled trial to determine effectiveness for preventing TDV and promoting healthy relationship behaviors among middle school students. In this study, we examine the prevention effects on secondary outcomes, including victimization and perpetration of physical violence, bullying, and cyberbullying. This study examined the effectiveness of Dating Matters compared to a standard-of-care TDV prevention program in 46 middle schools in four high-risk urban communities across the USA. The analytic sample (N?=?3301; 53% female; 50% Black, non-Hispanic; and 31% Hispanic) consisted of 6th–8th grade students who had an opportunity for exposure to Dating Matters in all three grades or the standard-of-care in 8th grade only. Results demonstrated that both male and female students attending schools implementing Dating Matters reported 11% less bullying perpetration and 11% less physical violence perpetration than students in comparison schools. Female Dating Matters students reported 9% less cyberbullying victimization and 10% less cyberbullying perpetration relative to the standard-of-care. When compared to an existing evidence-based intervention for TDV, Dating Matters demonstrated protective effects on physical violence, bullying, and cyberbullying for most groups of students. The Dating Matters comprehensive prevention model holds promise for reducing multiple forms of violence among middle school-aged youth. ClinicalTrials.gov Identifier: NCT01672541

     

Activation of the bacterial thermosensor DesK involves a serine zipper dimerization motif that is modulated by bilayer thickness

DesK is a bacterial thermosensor protein involved in maintaining membrane fluidity in response to changes in environmental temperature. Most likely, the protein is activated by changes in membrane thickness, but the molecular mechanism of sensing and signaling is still poorly understood. Here we aimed to elucidate the mode of action of DesK by studying the so-called “minimal sensor DesK” (MS-DesK), in which sensing and signaling are captured in a single transmembrane segment. This simplified version of the sensor allows investigation of membrane thickness-dependent protein–lipid interactions simply by using synthetic peptides, corresponding to the membrane-spanning parts of functional and nonfunctional mutants of MS-DesK incorporated in lipid bilayers with varying thicknesses. The lipid-dependent behavior of the peptides was investigated by circular dichroism, tryptophan fluorescence, and molecular modeling. These experiments were complemented with in vivo functional studies on MS-DesK mutants. Based on the results, we constructed a model that suggests a new mechanism for sensing in which the protein is present as a dimer and responds to an increase in bilayer thickness by membrane incorporation of a C-terminal hydrophilic motif. This results in exposure of three serines on the same side of the transmembrane helices of MS-DesK, triggering a switching of the dimerization interface to allow the formation of a serine zipper. The final result is activation of the kinase state of MS-DesK.All organisms have to be able to rapidly adapt to a vast variety of external stimuli to survive. In bacteria, two-component signal transduction systems are some of the most abundant mechanisms for sensing and adapting to changes in the extracellular environment. These systems mediate responses in chemotaxis and phototaxis, and regulate feedback to changes in osmolarity, redox state, and temperature (1, 2). However, despite the evident importance of two-component systems for bacterial survival, the molecular mechanisms of signal transduction via these systems have barely begun to be untangled.The DesKR system is a two-component system first identified in the soil bacterium Bacillus subtilis (3). Together with other regulatory systems, it is involved in maintaining membrane fluidity when the environmental temperature changes. The DesKR system works as follows. The actual thermosensor—i.e., the protein that senses the temperature change—is DesK. This protein consists of five transmembrane helices and an intracellular catalytic domain (DesKC) and is believed to function as a dimer (2, 4). In response to decreased environmental temperature, DesKC phosphorylates the response regulator DesR, which in turn controls the expression levels of the effector enzyme, a desaturase. This desaturase is inserted into the membrane, where it can introduce double bonds into preexisting lipids, allowing the recovery of membrane fluidity at this lower temperature (3).In the present study, we focused on the first step of the signaling pathway, examining how the sensor is able to sense and transmit a temperature-dependent signal. This challenge was recently simplified by the discovery that both the sensing and the signal transduction properties of the membrane-spanning part of DesK can be captured into a single transmembrane segment by fusing the N-terminal part of the first transmembrane segment to the C-terminal part of the fifth transmembrane segment (5). The resulting protein is called the minimal sensor DesK (MS-DesK).Importantly, MS-DesK shows a temperature-dependent switch in activity comparable to the full-length DesK not only in vivo, but also when reconstituted in protein-free lipid bilayers made from bacterial lipids (5). Therefore, no other membrane proteins are involved in sensing or signal transduction. Furthermore, the activity of the catalytic domain DesKC itself, is not temperature-sensitive (5, 6), and thus it must be the transmembrane segment of MS-DesK that somehow reacts to changes in temperature, most likely by sensing corresponding changes in the physical properties of the lipids.Which properties of the membrane could be sensed by DesK and MS-DesK? On a decrease in environmental temperature, membrane lipids become more ordered, and consequently the membrane becomes thicker (7). Some evidence suggests that such changes in membrane thickness may be a key factor in the regulation of DesK sensing and signaling. First, an MS-DesK length mutant (4V) containing four extra valines in the C-terminal region of its transmembrane segment was found to be inactive and to remain locked in the phosphatase state on a decrease in temperature (5). Second, reconstitution studies showed increasing activity of both DesK and MS-DesK with increasing acyl chain length of the lipids in which the protein is reconstituted (5, 8). Third, increased incorporation of long-chain fatty acids into the membrane lipids was found to stimulate kinase activity of DesK in vivo, whereas increased levels of short-chain fatty acids result in loss of activity (9).How can membrane thickness regulate the activity of DesK? It has been shown that the N terminus of MS-DesK at the exoplasmic side of the membrane contains a motif that may render the protein sensitive to membrane thickness and interfacial hydration. This motif contains two hydrophilic amino acids, K10 and N12, that are essential for activity (5) and that presumably are located within the transmembrane region just below the lipid–water interface. Because their side chains can snorkel to the hydrophilic membrane–water interface, these amino acids were proposed to act as a buoy, stabilizing the position of the transmembrane segment. For this reason, this has been called the sunken-buoy (SB) motif (5). In addition to the SB motif, a charged linker region at the intracellular membrane–water interface was found to be important for activity (10). It has been proposed that both motifs act together as a molecular gauge that senses membrane thickness and thereby regulates the switching of activity of the intracellular catalytic domain of DesK (10). The molecular details of the mode of action of this molecular gauge have remained elusive, however.Because the activity of MS-DesK is most likely regulated by direct interactions of its single transmembrane segment with surrounding lipids, as discussed above, this system is ideally suited for studies on relatively simple model membranes. In such model systems, the biological complexity of the host membrane is reduced to allow for systematic studies. Here, to gain insight into the molecular mode of action of the sensor, we studied the behavior of peptides mimicking the membrane-spanning parts of a functional mutant and a nonfunctional mutant of MS-DesK in synthetic lipid bilayers by spectroscopic techniques and molecular modeling. Combined with in vivo functional studies on MS-DesK mutants and cross-linking experiments, our results lead to a new model of thermosensing in which changes in bilayer thickness trigger a switch between distinct dimerization interfaces within the membrane, resulting in activation of the sensor.     

Impact of a patient blood management program within an Orthogeriatric care service

Background

Patient blood management (PBM) performs multidisciplinary strategies to optimize red blood cell (RBC) transfusion. Orthogeriatric share care models (surgeon and geriatrician manage the patient together from admission) have the goal of improving outcomes in hip fracture patients.

Low-fat dairy products and blood pressure: follow-up of 2290 older persons at high cardiovascular risk participating in the PREDIMED study

High blood pressure (BP) has been ranked as the most important risk factor worldwide regarding attributable deaths. Dietary habits are major determinants of BP. Among them, frequent intake of low-fat dairy products may protect against hypertension. Our aim was to assess the relationship between low-fat dairy product intake and BP levels and their changes after 12-month follow-up in a cohort of asymptomatic older persons at high cardiovascular risk recruited into a large-scale trial assessing the effects of Mediterranean diets on cardiovascular outcomes. Data from 2290 participants, including 1845 with hypertension, were available for analyses. Dairy products were not a specific part of the intervention; thus, data were analysed as an observational cohort. Dietary information was collected with validated semi-quantitative FFQ and trained personnel measured BP. To assess BP changes, we undertook cross-sectional analyses at baseline and at the end of follow-up and longitudinal analyses. A statistically significant inverse association between low-fat dairy product intake and systolic BP was observed for the 12-month longitudinal analysis. In the longitudinal analysis, the adjusted systolic and diastolic BP were significantly lower in the highest quintile of low-fat dairy product intake (-4.2 (95% CI -6.9, -1.4) and -1.8 (95% CI -3.2, -0.4) mmHg respectively), whereas the point estimates for the difference in diastolic BP indicated a modest non-significant inverse association. Intake of low-fat dairy products was inversely associated with BP in an older population at high cardiovascular risk, suggesting a possible protective effect against hypertension.     

The relationships of adolescent school-related deviant behaviour and victimization with psychological distress: testing a general model of the mediational role of parents and teachers across groups of gender and age

Deviant behaviour and victimization at school have been consistently related to poor psychological adjustment in adolescents. This research explores the mediating role that parents and teachers have in adolescent psychological distress in 973 Spanish students aged 11-16 years old. Structural equation analyses results showed that adolescent deviant behaviour and victimization were positively related to psychological distress as seen by the total effects. However, while victimization was directly related to psychological distress, the association of deviant behaviour and psychological distress was mediated by adolescent-parent communication and adolescent-teacher relationships. Multigroup analyses showed that relationships among variables were not significantly different for groups of age and gender.     

The c.-1639G > A polymorphism of the VKORC1 gene is a major determinant of the response to acenocoumarol in anticoagulated patients

Much of the variability in the sensitivity to warfarin in anticoagulated patients is associated with the c.-1639G > A polymorphism of the vitamin K-epoxide reductase (VKORC1) gene. However, its association with the acenocoumarol dose in patients under anticoagulant therapy has not been studied. The c.-1639G > A genotype of VKORC1 was determined in 113 patients on stable anticoagulation requiring low (n = 42), medium (n = 42) or high (n = 21) acenocoumarol doses. To evaluate the association between acenocoumarol requirements and the c.-1639G > A variant, multivariate logistic regression models were fitted, adjusting for age, gender, and the c.430C > T and c.1075A > C variants of cytochrome P450 2C9 (CYP2C9). A total of 90.5% of the patients in the low acenocoumarol dose group carried the A allele of VKORC1:c.-1639G > A. The A allele independently increased the odds of requiring a low acenocoumarol dose [odds ratio (OR) 9.4; 95% confidence interval (CI) 1.9-46.4; P = 0.006], especially when the homozygous form was present (OR 44.2; 95% CI 5.5-354.6; P < 0.001). The A allele was less frequent in the high dose group showing an inverse association with the requirement for high doses (OR 0.04; 95% CI 0.01-0.22; P < 0.001). The A allele of the c.-1639G > A polymorphism of VKORC1 is therefore associated with a low-dose requirement for acenocoumarol in patients receiving anticoagulant therapy.