Blocking the deadly effects of the NMDA receptor in stroke.

Excessive activation of NMDA glutamate receptors contributes to neuronal death after stroke. In this issue, Tu et al. (2010) demonstrate that ischemic injury promotes the association of death-associated protein kinase 1 with the NMDA receptor, thereby potentiating its activity, and show that disrupting this association reduces damage to the brain.

Comparison of Subjective Responses to Oral and Intravenous Alcohol Administration Under Similar Systemic Exposures.

BACKGROUND: Individuals perceive the effects of alcohol differently, and the variation is commonly used in research assessing the risk for developing an alcohol use disorder. Such research is supported by both oral and intravenous (IV) alcohol administration techniques, and any differences attributable to the route employed should be understood. Our objective was to test whether an individual's subjective responses to alcohol are similar when the breath alcohol concentration (BrAC) trajectory resulting from oral administration is matched by IV administration. METHODS: We conducted a 2-session, within-subject study in 44 young adult, healthy, nondependent drinkers (22 females and 22 males). In the first session, subjects ingested a dose of alcohol which was individually calculated, on the basis of total body water, to yield a peak BrAC near 80 mg/dl, and the resulting BrAC trajectory was recorded. A few days later, subjects received an IV alcohol infusion rate profile, precomputed to replicate each individual's oral alcohol BrAC trajectory. In both sessions, we assessed 4 subjective responses to alcohol: SEDATION, SIMULATION, INTOXICATION, and HIGH; at baseline and frequently for 4 hours. We compared the individuals' baseline-corrected responses at peak BrAC and at half-peak BrAC on both the ascending and descending limbs. We also computed and compared Pearson-product moment correlations of responses by route of administration, the Mellanby measure of acute adaptation to alcohol, and the area under the entire response curve for each subjective response. RESULTS: No significant differences in any measure could be attributed to the route of alcohol administration. Eleven of 12 response comparisons were significantly correlated across the routes of alcohol administration, with 9 surviving correction for multiple measures, as did the Mellanby effect and area under the response curve correlations. CONCLUSIONS: The route of alcohol administration has a minimal effect on subjective responses to alcohol when an individual's BrAC exposure profiles are similar.

Sex Differences in Motivation to Self-Administer Alcohol After 2 Weeks of Abstinence in Young-Adult Heavy Drinkers.

BACKGROUND: Studies in animal models document that forced abstinence from usual consumption of alcohol changes subsequent seeking and consumption, with increases or decreases depending on the species, duration of abstinence, number of deprivations, and sex. Human laboratory-based alcohol deprivation studies are rare. METHODS: We conducted a 2-session, within-participant, randomized-order comparison of intravenous, progressive ratio, alcohol self-administration during 2.5 hours of progressive work for alcohol and/or vehicle; once while the participants pursued their usual drinking habits and once after 2 weeks of closely monitored, voluntary outpatient abstinence from alcohol. The schedule of work for rewards and the incremental increases in breath alcohol concentration following completion of an alcohol work-set were identical across participants. Fifty young-adult (27 men), heavy-drinking participants completed both sessions. Our primary hypothesis was that motivation to work for alcohol after 2 weeks of abstinence would be greater in participants with a weekly binge pattern of drinking, compared to those who regularly drink heavily, and we intended to explore associations with biological family history of alcoholism and sex. RESULTS: We detected no change in work for alcohol associated with recent drinking history. However, females, on average, increased their work for alcohol upon resumption after 2 weeks of abstinence (mean ± SEM = +16.3 ± 9.6%), while males decreased that work (-24.8 ± 13.8%). The sex difference was substantial and significant (p < 0.03), with a medium effect size (Cohen's d = 0.63). CONCLUSIONS: We believe a more comprehensive study of mechanisms underlying the sex differences in the human postabstinence response is warranted.

Differential Adulthood Onset mGlu5 Signaling Saves Prefrontal Function in the Fragile X Mouse.

The final maturation of the prefrontal cortex (PFC) continues into early adulthood and is delayed compared with other forebrain structures. However, how these late onset changes in the PFC relate to neurodevelopment disorders is poorly understood. Fragile X syndrome (FXS) is a prevalent neurogenetic disorder linked to deficits in PFC function. mGlu5 is an important molecular hub in the etiology of FXS. Thus we have examined changes in mGlu5 function in the PFC in a mouse model of FXS (Fmr1 knockout) during early adulthood and subsequent maturity. An unusual endophenotype was identified; during early adulthood (2-month-old) Fmr1 knockout mice show a severe deficit in mGlu5 dependent eCB synaptic plasticity; however, in 1-year-old this deficit self rectifies. This adulthood onset correction in mGlu5 function is linked to an engagement of TRPV1 receptors in 1-year-old mice. In 2-month-old Fmr1 knockout mice, mGlu5 mediated synaptic plasticity could be recovered with eCB system targeted drugs, but also by direct enhancement of mGlu5 function with a positive allosteric modulator. These results point to further refinements to the role of mGlu5 in FXS. Furthermore our findings suggest when studying neurodevelopmental disorders with a significant PFC phenotype consideration of late onset changes may be important.

Age-Dependent Long-Term Potentiation Deficits in the Prefrontal Cortex of the Fmr1 Knockout Mouse Model of Fragile X Syndrome.

The most common inherited monogenetic cause of intellectual disability is Fragile X syndrome (FXS). The clinical symptoms of FXS evolve with age during adulthood; however, neurophysiological data exploring this phenomenon are limited. The Fmr1 knockout (Fmr1KO) mouse models FXS, but studies in these mice of prefrontal cortex (PFC) function are underrepresented, and aging linked data are absent. We studied synaptic physiology and activity-dependent synaptic plasticity in the medial PFC of Fmr1KO mice from 2 to 12 months. In young adult Fmr1KO mice, NMDA receptor (NMDAR)-mediated long-term potentiation (LTP) is intact; however, in 12-month-old mice this LTP is impaired. In parallel, there was an increase in the AMPAR/NMDAR ratio and a concomitant decrease of synaptic NMDAR currents in 12-month-old Fmr1KO mice. We found that acute pharmacological blockade of mGlu5 receptor in 12-month-old Fmr1KO mice restored a normal AMPAR/NMDAR ratio and LTP. Taken together, the data reveal an age-dependent deficit in LTP in Fmr1KO mice, which may correlate to some of the complex age-related deficits in FXS.

Basket to Purkinje Cell Inhibitory Ephaptic Coupling Is Abolished in Episodic Ataxia Type 1.

Dominantly inherited missense mutations of the KCNA1 gene, which encodes the KV1.1 potassium channel subunit, cause Episodic Ataxia type 1 (EA1). Although the cerebellar incoordination is thought to arise from abnormal Purkinje cell output, the underlying functional deficit remains unclear. Here we examine synaptic and non-synaptic inhibition of Purkinje cells by cerebellar basket cells in an adult mouse model of EA1. The synaptic function of basket cell terminals was unaffected, despite their intense enrichment for KV1.1-containing channels. In turn, the phase response curve quantifying the influence of basket cell input on Purkine cell output was maintained. However, ultra-fast non-synaptic ephaptic coupling, which occurs in the cerebellar 'pinceau' formation surrounding the axon initial segment of Purkinje cells, was profoundly reduced in EA1 mice in comparison with their wild type littermates. The altered temporal profile of basket cell inhibition of Purkinje cells underlines the importance of Kv1.1 channels for this form of signalling, and may contribute to the clinical phenotype of EA1.

Seemingly unrelated time series model for forecasting the peak and short-term electricity demand: Evidence from the Kalman filtered Monte Carlo method.

In this extant paper, a multivariate time series model using the seemingly unrelated times series equation (SUTSE) framework is proposed to forecast the peak and short-term electricity demand using time series data from February 2, 2014, to August 2, 2018. Further the Markov Chain Monte Carlo (MCMC) method, Gibbs Sampler, together with the Kalman Filter were applied to the SUTSE model to simulate the variances to predict the next day's peak and electricity demand. Relying on the study results, the running ergodic mean showed the convergence of the MCMC process. Before forecasting the peak and short-term electricity demand, a week's prediction from the 28th to the 2nd of August of 2018 was analyzed and it found that there is a possible decrease in the daily energy over time. Further, the forecast for the next day (August 3, 2018) was about 2187 MW and 44090 MWh for the peak and electricity demands respectively. Finally, the robustness of the SUTSE model was assessed in comparison to the SUTSE model without MCMC. Evidently, SUTSE with the MCMC method had recorded an accuracy of about 96% and 95.8% for Peak demand and daily energy respectively.

Alcohol intoxication progressively impairs drivers' capacity to detect important environmental stimuli.

RATIONALE: Alcohol intoxication impairs driving skills, leading to an increased frequency of accidents and crash fatalities. Inebriation may specifically impair environmental vigilance, reducing the driver's capacity for attention to stimuli that are relevant to successful navigation. OBJECTIVES: We examined the separate and interactive effects of breath alcohol concentration (BrAC) and simulated driving scenario on the capacity to correctly identify visual stimuli embedded in the environment. METHODS: Ten healthy young adult drivers (6 males; 4 females) each performed 4 driving scenarios at each of 3 steady breath alcohol concentration levels (0, 60 and 100 mg/dl). Scenarios were based on speed or distance keeping while navigating a rural 2-lane road in daytime or nighttime conditions. Drivers pressed a button on the steering wheel corresponding to the direction of an arrow (up or down) which appeared briefly on road signs embedded in the environment, either overhead or on the roadside. RESULTS: Increasing level of BrAC and subjective scenario difficulty manifested significant, separate, but not interactive influences in association with the number of arrows correctly identified. Significant impairments could be detected at a level of BrAC below the current American limit for legal operation of a motor vehicle. CONCLUSIONS: Environmental vigilance is subject to impairment by either/both alcohol intoxication and driving conditions.

Effects of Static Correlation between Spin Centers in Multicenter Transition Metal Complexes.

Multicenter transition metal complexes are the key moieties of many processes in chemistry, biochemistry, and materials science such as in the active sites of enzymes, molecular catalysts, and biological electron carriers. Their electronic structure, often characterized by high-spin-polarized metal sites, is a challenge for theoretical chemists because of their high degree of dynamical and static correlation. Static correlation is necessary both for the appropriate description of the metal-ligand bonding and for a correct description of the multideterminant character arising from the magnetic interactions between spin centers. Density functional theory (DFT) is usually applied using a single-determinant broken-symmetry state that is lacking the correct spin symmetry when the ground state has total low-spin character. To alleviate this drawback, we use the extended broken-symmetry (EBS) approach to derive approximate ground-state energies and, for the first time, forces for the correctly symmetric ground state of an arbitrary number of spin centers within the framework of the Heisenberg-Dirac-van Vleck Hamiltonian. Remarkably, the proposed procedure supplies relaxed geometries that are fully consistent with the calculated J-coupling constants. We apply the method to investigate the relaxed geometrical structure of the low-spin ground state of iron-sulfur clusters with two, three, and four iron centers. We observed significant differences in both geometrical parameters and coupling constant J between the symmetrized ground state, the high-spin, and the broken-symmetry optimized structures. These changes are often comparable with the differences observed by using different functionals, and the use of EBS always improves the description of the studied systems. It will be therefore important to include it in any DFT attempt to quantitatively describe multicenter transition metal complexes in the future.

Endocannabinoids Mediate Muscarinic Acetylcholine Receptor-Dependent Long-Term Depression in the Adult Medial Prefrontal Cortex.

Cholinergic inputs into the prefrontal cortex (PFC) are associated with attention and cognition; however there is evidence that acetylcholine also has a role in PFC dependent learning and memory. Muscarinic acetylcholine receptors (mAChR) in the PFC can induce synaptic plasticity, but the underlying mechanisms remain either opaque or unresolved. We have characterized a form of mAChR mediated long-term depression (LTD) at glutamatergic synapses of layer 5 principal neurons in the adult medial PFC. This mAChR LTD is induced with the mAChR agonist carbachol and inhibited by selective M1 mAChR antagonists. In contrast to other cortical regions, we find that this M1 mAChR mediated LTD is coupled to endogenous cannabinoid (eCB) signaling. Inhibition of the principal eCB CB1 receptor blocked carbachol induced LTD in both rats and mice. Furthermore, when challenged with a sub-threshold carbachol application, LTD was induced in slices pretreated with the monoacylglycerol lipase (MAGL) inhibitor JZL184, suggesting that the eCB 2-arachidonylglyerol (2-AG) mediates M1 mAChR LTD. Yet, when endogenous acetylcholine was released from local cholinergic afferents in the PFC using optogenetics, it failed to trigger eCB-LTD. However coupling patterned optical and electrical stimulation to generate local synaptic signaling allowed the reliable induction of LTD. The light-electrical pairing induced LTD was M1 mAChR and CB1 receptor mediated. This shows for the first time that connecting excitatory synaptic activity with coincident endogenously released acetylcholine controls synaptic gain via eCB signaling. Together these results shed new light on the mechanisms of synaptic plasticity in the adult PFC and expand on the actions of endogenous cholinergic signaling.

Late onset deficits in synaptic plasticity in the valproic acid rat model of autism.

Valproic acid (VPA) is a frequently used drug in the treatment of epilepsy, bipolar disorders and migraines; however it is also a potent teratogen. Prenatal exposure increases the risk of childhood malformations and can result in cognitive deficits. In rodents in utero exposure to VPA also causes neurodevelopmental abnormalities and is an important model of autism. In early postnatal life VPA exposed rat pups show changes in medial prefrontal cortex (mPFC) physiology and synaptic connectivity. Specifically, principal neurons show decreased excitability but increased local connectivity, coupled with an increase in long-term potentiation (LTP) due to an up-regulation of NMDA receptor (NMDAR) expression. However recent evidence suggests compensatory homeostatic mechanisms lead to normalization of synaptic NMDARs during later postnatal development. Here we have extended study of mPFC synaptic physiology into adulthood to better understand the longitudinal consequences of early developmental abnormalities in VPA exposed rats. Surprisingly in contrast to early postnatal life and adolescence, we find that adult VPA exposed rats show reduced synaptic function. Both NMDAR mediated currents and LTP are lower in adult VPA rats, although spontaneous activity and endocannabinoid dependent long-term depression are normal. We conclude that rather than correcting, synaptic abnormalities persist into adulthood in VPA exposed rats, although a quite different synaptic phenotype is present. This switch from hyper to hypo function in mPFC may be linked to some of the neurodevelopmental defects found in prenatal VPA exposure and autism spectrum disorders in general.

Stabilization of fatigue fractures of the dorsal pelvis with a trans-sacral bar. Operative technique and outcome.

INTRODUCTION: Due to ageing of our population the number of fatigue fractures of the pelvic ring is steadily growing. These fractures are often treated with bed rest but may result in a disabling immobility with severe pain. An operative treatment is an option in these cases. The aim of operative treatment is bony healing obtained by stable fixation giving back to the patient's previous mobility. Optimal surgical treatment is currently under debate. Sacroiliac screw fixation and sacroplasty are used for stabilization of the dorsal pelvis. Due to the technique and the low density of spongious sacral bone, no or only low compression in the fracture site is obtained, which may inhibit bony healing. The trans-sacral bar compression osteosynthesis is presented as an alternative procedure. We present the outcome of 11 patients, who were treated with this method. METHODS: The patient is placed in prone position on the operation table. Under image intensifier control, a 5mm threaded sacral bar is inserted through the body of S1 from the left to the right dorsal ilium. Nuts are placed over the bar achieving fracture compression. When anterior pelvic instability is present, an anterior osteosynthesis is also performed. Clinical and radiological outcome were evaluated one year after index surgery with different scoring systems. RESULTS: Eleven patients (9 F and 2 M) were treated between 2005 and 2010. The mean age of the patients was 73 years at time of operation. There were no mechanical complications. Postoperatively there was a temporary nerve palsy of L5 in one case. The mean follow-up was 14 months. In all patients, a bony healing of the dorsal pelvic ring was achieved. Seven patients showed a major clinical improvement, in four patients a moderate. CONCLUSIONS: Trans-sacral bar osteosynthesis is a promising method for stabilization of fatigue fractures of the pelvic ring. Only with this method, a high interfragmentary compression is achieved, independent of the quality of the spongious bone of the sacral body.

Uncoupling of the endocannabinoid signalling complex in a mouse model of fragile X syndrome.

Fragile X syndrome, the most commonly known genetic cause of autism, is due to loss of the fragile X mental retardation protein, which regulates signal transduction at metabotropic glutamate receptor-5 in the brain. Fragile X mental retardation protein deletion in mice enhances metabotropic glutamate receptor-5-dependent long-term depression in the hippocampus and cerebellum. Here we show that a distinct type of metabotropic glutamate receptor-5-dependent long-term depression at excitatory synapses of the ventral striatum and prefrontal cortex, which is mediated by the endocannabinoid 2-arachidonoyl-sn-glycerol, is absent in fragile X mental retardation protein-null mice. In these mutants, the macromolecular complex that links metabotropic glutamate receptor-5 to the 2-arachidonoyl-sn-glycerol-producing enzyme, diacylglycerol lipase-α (endocannabinoid signalosome), is disrupted and metabotropic glutamate receptor-5-dependent 2-arachidonoyl-sn-glycerol formation is compromised. These changes are accompanied by impaired endocannabinoid-dependent long-term depression. Pharmacological enhancement of 2-arachidonoyl-sn-glycerol signalling normalizes this synaptic defect and corrects behavioural abnormalities in fragile X mental retardation protein-deficient mice. The results identify the endocannabinoid signalosome as a molecular substrate for fragile X syndrome, which might be targeted by therapy.

Essential role of SBP-1 activation in oxygen deprivation induced lipid accumulation and increase in body width/length ratio in Caenorhabditis elegans.

Epidemiological evidence suggests a link between chronic oxygen starvation and fat accumulation/obesity, however the underlying mechanism remains unclear. Using Caenorhabditis elegans we found extended oxygen deprivation resulted in activation of SBP-1, the worm homologue of SREBP1, a transcription factor important in maintaining lipid homeostasis. SBP-1 knockdown prevented hypoxia-induced fat accumulation and the associated increase in worm width/length ratio, demonstrating that SBP-1/SREBP1 plays an essential role in hypoxia-induced lipid accumulation and body shape alteration. This study provides the first evidence suggesting that activation of SREBP1 may be a critical pathogenic factor contributing to chronic hypoxia associated excessive fat accumulation/obesity in humans.

Role of NMDA receptor-dependent activation of SREBP1 in excitotoxic and ischemic neuronal injuries.

Excitotoxic neuronal damage caused by overactivation of N-methyl-D-aspartate glutamate receptors (NMDARs) is thought to be a principal cause of neuronal loss after stroke and brain trauma. Here we report that activation of sterol regulatory element binding protein-1 (SREBP-1) transcription factor in affected neurons is an essential step in NMDAR-mediated excitotoxic neuronal death in both in vitro and in vivo models of stroke. The NMDAR-mediated activation of SREBP-1 is a result of increased insulin-induced gene-1 (Insig-1) degradation, which can be inhibited with an Insig-1-derived interference peptide (Indip) that we have developed. Using a focal ischemia model of stroke, we show that systemic administration of Indip not only prevents SREBP-1 activation but also substantially reduces neuronal damage and improves behavioral outcome. Our study suggests that agents that reduce SREBP-1 activation such as Indip may represent a new class of neuroprotective therapeutics against stroke.

Plastid movement in statocytes of the arg1 (altered response to gravity) mutant.

The ability of a plant to respond to gravity is crucial for growth and development throughout the life cycle. A key player in the cellular mechanisms of gravitropism is ARG1 (altered response to gravity), a DnaJ-like protein that associates with components of the vesicular trafficking pathway and carries a C-terminal domain with similarities to cytoskeleton-associated proteins. The arg1-2 mutant of Arabidopsis thaliana has reduced and delayed gravitropism in roots, shoots, and inflorescence stems when grown in the light or dark. We performed light microscopic studies of plastid movement in the gravity-perceiving statocytes (endodermal cells) of hypocotyls of arg1-2 and WT light-grown seedlings following reorientation to better characterize the role of ARG1 in gravitropism. Cryofixation/freeze substitution procedures were used because they provide a reliable indication of rapid cellular events within the statocytes. Our results suggest that ARG1 affects gravitropism by reducing plastid movement/sedimentation, a process known to be essential for early phases of signaling cascades in the statocytes.

Novel putative targets of N-ethylmaleimide sensitive fusion protein (NSF) and alpha/beta soluble NSF attachment proteins (SNAPs) include the Pak-binding nucleotide exchange factor betaPIX.

N-ethylmaleimide sensitive fusion protein (NSF) is a chaperone that plays a crucial role in the fusion of vesicles with target membranes. NSF mediates the ATP-consuming dissociation of a core protein complex that assembles during vesicle fusion and it thereby recharges the fusion machinery to perform multiple rounds of fusion. The binding of NSF to the core complex is mediated by co-chaperones named soluble NSF attachment proteins (SNAPs), for which three isoforms (alpha, beta and gamma) are known. Here, we sought to identify novel targets of the NSF-SNAP complex. A yeast two-hybrid screen using the brain specific betaSNAP isoform as bait revealed, as expected, NSF and several isoforms of the SNARE protein syntaxin as interactors. In addition, three isoforms of the reticulon protein family and two isoforms of BNIP3 interacted with betaSNAP. A yeast two-hybrid screen using NSF as bait identified Rab11-FIP3 and the Pak-binding nucleotide exchange factor betaPIX as putative binding partners. betaPIX interacts with recombinant NSF in co-sedimentation assays and the two proteins may be co-immunoprecipitated. A leucine zipper (LZ) motif within the C-terminus of betaPIX mediates binding to NSF; however, this fragment of betaPIX does not exhibit dominant negative effects in a cellular assay. In summary, our results support the evolving view that NSF has numerous targets in addition to conventional SNARE complexes.