Monitoring synaptic transmission in primary neuronal cultures using local extracellular stimulation

Various techniques have been applied for the functional analysis of synaptic transmission in Cultured neurons. Here, we describe a method of studying synaptic transmission in neurons cultured at high-density from different brain regions such as the cortex, striatum and spinal cord. We use postsynaptic whole-cell recordings to monitor synaptic Currents triggered by presynaptic action potentials that are induced by brief stimulations with a nearby extracellular bipolar electrode. Pharmacologically isolated excitatory or inhibitory postsynaptic currents can be reliably induced, with amplitudes, synaptic charge transfers, and short-term plasticity properties that are reproducible from culture to culture. We show that the size and kinetics of pharmacologically isolated inhibitory postsynaptic Currents triggered by single action potentials or stimulus trains depend on the Ca2+ concentration, temperature and stimulation frequency. This method can be applied to study synaptic transmission in wildtype neurons infected with lentiviruses encoding various components of presynaptic release machinery, or in neurons from genetically modified mice, for example neurons carrying floxed genes in which gene expression can be acutely ablated by expression of Cre recombinase. The preparation described in this paper should be useful for analysis of synaptic transmission in inter-neuronal synapses formed by different types of neurons. (c) 2006 Elsevier B.V. All rights reserved

Deterministic Partial Differential Equation Model for Dose Calculation in Electron Radiotherapy

Treatment with high energy ionizing radiation is one of the main methods in modern cancer therapy that is in clinical use. During the last decades, two main approaches to dose calculation were used, Monte Carlo simulations and semi-empirical models based on Fermi-Eyges theory. A third way to dose calculation has only recently attracted attention in the medical physics community. This approach is based on the deterministic kinetic equations of radiative transfer. Starting from these, we derive a macroscopic partial differential equation model for electron transport in tissue. This model involves an angular closure in the phase space. It is exact for the free-streaming and the isotropic regime. We solve it numerically by a newly developed HLLC scheme based on [BerCharDub], that exactly preserves key properties of the analytical solution on the discrete level. Several numerical results for test cases from the medical physics literature are presented.Comment: 20 pages, 7 figure

Expanding the clinical phenotype of the 3q29 microdeletion syndrome and characterization of the reciprocal microduplication

<p>Abstract</p> <p>Background</p> <p>Interstitial deletions of 3q29 have been recently described as a microdeletion syndrome mediated by nonallelic homologous recombination between low-copy repeats resulting in an ~1.6 Mb common-sized deletion. Given the molecular mechanism causing the deletion, the reciprocal duplication is anticipated to occur with equal frequency, although only one family with this duplication has been reported.</p> <p>Results</p> <p>In this study we describe 14 individuals with microdeletions of 3q29, including one family with a mildly affected mother and two affected children, identified among 14,698 individuals with idiopathic mental retardation who were analyzed by array CGH. Eleven individuals had typical 1.6-Mb deletions. Three individuals had deletions that flank, span, or partially overlap the commonly deleted region. Although the clinical presentations of individuals with typical-sized deletions varied, several features were present in multiple individuals, including mental retardation and microcephaly. We also identified 19 individuals with duplications of 3q29, five of which appear to be the reciprocal duplication product of the 3q29 microdeletion and 14 of which flank, span, or partially overlap the common deletion region. The clinical features of individuals with microduplications of 3q29 also varied with few common features. <it>De novo </it>and inherited abnormalities were found in both the microdeletion and microduplication cohorts illustrating the need for parental samples to fully characterize these abnormalities.</p> <p>Conclusion</p> <p>Our report demonstrates that array CGH is especially suited to identify chromosome abnormalities with unclear or variable presentations.</p

Teaching psychology to student nurses: the use of talking heads videos

Psychology is a central part of undergraduate nursing curricula in the UK.However, student nurses report difficulties recognising the relevance and value of psychology. We sought to strengthen first-year student nurses’ application of psychology by developing a set of digital stories based around ‘Talking Head’video clips where authentic patients relate their experiences of illness and nursing care. The aim of this article is to discuss the technological, organisational and pedagogical challenges, student and staff evaluations and our recommendations for the future of Talking Heads. First-year student nurses were shown a video clip of a patient talking about their illness experiences followed by a group learning situation linking main themes to psychology and nursing. Students and staff valued the authenticity of patient’s narrative, found the video clip easy to follow,reported a raised awareness of psychological concepts and improved empathetic understanding of chronic illness. Negative evaluations were related to a sanitised, untypical representation and limited internet access. This small-scale study highlighted how patient narrative may enhance students understanding of illness experience. It chronicles the development and evaluation of a Talking Head in a specific context but which may be useful across disciplines

Investigation of NRXN1 deletions: Clinical and molecular characterization

Deletions at 2p16.3 involving exons of NRXN1 are associated with susceptibility for autism and schizophrenia, and similar deletions have been identified in individuals with developmental delay and dysmorphic features. We have identified 34 probands with exonic NRXN1 deletions following referral for clinical microarray‐based comparative genomic hybridization. To more firmly establish the full phenotypic spectrum associated with exonic NRXN1 deletions, we report the clinical features of 27 individuals with NRXN1 deletions, who represent 23 of these 34 families. The frequency of exonic NRXN1 deletions among our postnatally diagnosed patients (0.11%) is significantly higher than the frequency among reported controls (0.02%; P  = 6.08 × 10 −7 ), supporting a role for these deletions in the development of abnormal phenotypes. Generally, most individuals with NRXN1 exonic deletions have developmental delay (particularly speech), abnormal behaviors, and mild dysmorphic features. In our cohort, autism spectrum disorders were diagnosed in 43% (10/23), and 16% (4/25) had epilepsy. The presence of NRXN1 deletions in normal parents and siblings suggests reduced penetrance and/or variable expressivity, which may be influenced by genetic, environmental, and/or stochastic factors. The pathogenicity of these deletions may also be affected by the location of the deletion within the gene. Counseling should appropriately represent this spectrum of possibilities when discussing recurrence risks or expectations for a child found to have a deletion in NRXN1 . © 2013 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97220/1/35780_ftp.pd

Spatial chemical distance based on atomic property fields

Similarity of compound chemical structures often leads to close pharmacological profiles, including binding to the same protein targets. The opposite, however, is not always true, as distinct chemical scaffolds can exhibit similar pharmacology as well. Therefore, relying on chemical similarity to known binders in search for novel chemicals targeting the same protein artificially narrows down the results and makes lead hopping impossible. In this study we attempt to design a compound similarity/distance measure that better captures structural aspects of their pharmacology and molecular interactions. The measure is based on our recently published method for compound spatial alignment with atomic property fields as a generalized 3D pharmacophoric potential. We optimized contributions of different atomic properties for better discrimination of compound pairs with the same pharmacology from those with different pharmacology using Partial Least Squares regression. Our proposed similarity measure was then tested for its ability to discriminate pharmacologically similar pairs from decoys on a large diverse dataset of 115 protein–ligand complexes. Compared to 2D Tanimoto and Shape Tanimoto approaches, our new approach led to improvement in the area under the receiver operating characteristic curve values in 66 and 58% of domains respectively. The improvement was particularly high for the previously problematic cases (weak performance of the 2D Tanimoto and Shape Tanimoto measures) with original AUC values below 0.8. In fact for these cases we obtained improvement in 86% of domains compare to 2D Tanimoto measure and 85% compare to Shape Tanimoto measure. The proposed spatial chemical distance measure can be used in virtual ligand screening

Polarity Changes in the Transmembrane Domain Core of HIV-1 Vpu Inhibits Its Anti-Tetherin Activity

Tetherin (BST-2/CD317) is an interferon-inducible antiviral protein that restricts the release of enveloped viruses from infected cells. The HIV-1 accessory protein Vpu can efficiently antagonize this restriction. In this study, we analyzed mutations of the transmembrane (TM) domain of Vpu, including deletions and substitutions, to delineate amino acids important for HIV-1 viral particle release and in interactions with tetherin. The mutants had similar subcellular localization patterns with that of wild-type Vpu and were functional with respect to CD4 downregulation. We showed that the hydrophobic binding surface for tetherin lies in the core of the Vpu TM domain. Three consecutive hydrophobic isoleucine residues in the middle region of the Vpu TM domain, I15, I16 and I17, were important for stabilizing the tetherin binding interface and determining its sensitivity to tetherin. Changing the polarity of the amino acids at these positions resulted in severe impairment of Vpu-induced tetherin targeting and antagonism. Taken together, these data reveal a model of specific hydrophobic interactions between Vpu and tetherin, which can be potentially targeted in the development of novel anti-HIV-1 drugs

Maternal mental health predicts risk of developmental problems at 3 years of age: follow up of a community based trial

<p>Abstract</p> <p>Background</p> <p>Undetected and untreated developmental problems can have a significant economic and social impact on society. Intervention to ameliorate potential developmental problems requires early identification of children at risk of future learning and behaviour difficulties. The objective of this study was to estimate the prevalence of risk for developmental problems among preschool children born to medically low risk women and identify factors that influence outcomes.</p> <p>Methods</p> <p>Mothers who had participated in a prenatal trial were followed up three years post partum to answer a telephone questionnaire. Questions were related to child health and development, child care, medical care, mother's lifestyle, well-being, and parenting style. The main outcome measure was risk for developmental problems using the Parents' Evaluation of Developmental Status (PEDS).</p> <p>Results</p> <p>Of 791 children, 11% were screened by the PEDS to be at high risk for developmental problems at age three. Of these, 43% had previously been referred for assessment. Children most likely to have been referred were those born preterm. Risk factors for delay included: male gender, history of ear infections, a low income environment, and a mother with poor emotional health and a history of abuse. A child with these risk factors was predicted to have a 53% chance of screening at high risk for developmental problems. This predicted probability was reduced to 19% if the child had a mother with good emotional health and no history of abuse.</p> <p>Conclusion</p> <p>Over 10% of children were identified as high risk for developmental problems by the screening, and more than half of those had not received a specialist referral. Risk factors for problems included prenatal and perinatal maternal and child factors. Assessment of maternal health and effective screening of child development may increase detection of children at high risk who would benefit from early intervention.</p> <p>Trial registration</p> <p>Current Controlled Trials ISRCTN64070727</p