The prefusion structure of herpes simplex virus glycoprotein B.

Cell entry of enveloped viruses requires specialized viral proteins that mediate fusion with the host membrane by substantial structural rearrangements from a metastable pre- to a stable postfusion conformation. This metastability renders the herpes simplex virus 1 (HSV-1) fusion glycoprotein B (gB) highly unstable such that it readily converts into the postfusion form, thereby precluding structural elucidation of the pharmacologically relevant prefusion conformation. By identification of conserved sequence signatures and molecular dynamics simulations, we devised a mutation that stabilized this form. Functionally locking gB allowed the structural determination of its membrane-embedded prefusion conformation at sub-nanometer resolution and enabled the unambiguous fit of all ectodomains. The resulting pseudo-atomic model reveals a notable conservation of conformational domain rearrangements during fusion between HSV-1 gB and the vesicular stomatitis virus glycoprotein G, despite their very distant phylogeny. In combination with our comparative sequence-structure analysis, these findings suggest common fusogenic domain rearrangements in all class III viral fusion proteins.

Genetic and functional analyses demonstrate a role for abnormal glycinergic signaling in autism.

Autism spectrum disorder (ASD) is a common neurodevelopmental condition characterized by marked genetic heterogeneity. Recent studies of rare structural and sequence variants have identified hundreds of loci involved in ASD, but our knowledge of the overall genetic architecture and the underlying pathophysiological mechanisms remains incomplete. Glycine receptors (GlyRs) are ligand-gated chloride channels that mediate inhibitory neurotransmission in the adult nervous system but exert an excitatory action in immature neurons. GlyRs containing the α2 subunit are highly expressed in the embryonic brain, where they promote cortical interneuron migration and the generation of excitatory projection neurons. We previously identified a rare microdeletion of the X-linked gene GLRA2, encoding the GlyR α2 subunit, in a boy with autism. The microdeletion removes the terminal exons of the gene (GLRA2(Δex8-9)). Here, we sequenced 400 males with ASD and identified one de novo missense mutation, p.R153Q, absent from controls. In vitro functional analysis demonstrated that the GLRA2(Δex8)(-)(9) protein failed to localize to the cell membrane, while the R153Q mutation impaired surface expression and markedly reduced sensitivity to glycine. Very recently, an additional de novo missense mutation (p.N136S) was reported in a boy with ASD, and we show that this mutation also reduced cell-surface expression and glycine sensitivity. Targeted glra2 knockdown in zebrafish induced severe axon-branching defects, rescued by injection of wild type but not GLRA2(Δex8-9) or R153Q transcripts, providing further evidence for their loss-of-function effect. Glra2 knockout mice exhibited deficits in object recognition memory and impaired long-term potentiation in the prefrontal cortex. Taken together, these results implicate GLRA2 in non-syndromic ASD, unveil a novel role for GLRA2 in synaptic plasticity and learning and memory, and link altered glycinergic signaling to social and cognitive impairments.

Identification of congenital muscular dystonia 2 associated with an inherited GlyT2 defect in Belgian Blue cattle from the United Kingdom.

Two newborn Belgian Blue calves from a farm in the United Kingdom exhibited lateral recumbency, low head carriage and transient muscle spasms following tactile or auditory stimulation. DNA sequence analysis indicated that both calves were homozygous for the recessive congenital muscular dystonia type 2 (CMD2) mutation (c.809T>C, p.Leu270Pro) in SLC6A5, encoding the neuronal glycine transporter GlyT2. Further testing of animals from the index farm and a sample of Belgian Blue sires revealed an unexpectedly high frequency of CMD2 carriers. This implies that linked quantitative trait loci may be influencing the prevalence of CMD2 in the estimated 55,000 Belgian Blue cattle in the United Kingdom. We have therefore developed new inexpensive tests for the CMD2 allele that can be used to confirm diagnosis, identify carriers and guide future breeding strategy, thus avoiding animal distress/premature death and minimizing the future economic impact of this disorder.

Modeling the 3D structure of GPCRs from sequence.

G-protein-coupled receptors (GPCRs) are a large and functionally diverse protein superfamily, which form a seven transmembrane (TM) helices bundle with alternating extra-cellular and intracellular loops. GPCRs are considered to be one of the most important groups of drug targets because they are involved in a broad range of body functions and processes and are related to major diseases. In this paper we present a new technology, named PREDICT, for modeling the 3D structure of any GPCR from its amino acid sequence. This approach takes into account both internal protein properties (i.e., the amino acid sequence) and the properties of the membrane environment. Unlike competing approaches, the new technology does not rely on the single known structure of rhodopsin, and is thus capable of predicting novel GPCR conformations. We demonstrate the capabilities of PREDICT in reproducing the known experimental structure of rhodopsin. In principle, PREDICT-generated models offer new opportunities for structure-based drug discovery towards GPCR targets.

Interactive relationships between hospital patients' noise-induced stress and other stress with sleep.

OBJECTIVE: The purpose of this study was to test the hypothesis that hospital noise-induced subjective stress would interact with other subjective environmental and personal stress in a relationship with poorer patient sleep. METHODS: A secondary data analysis was done using correlations and hierarchical multiple regression. Ninety-seven cardiac patients participated after transfer from critical care to a general unit. The independent variables were assessed with Topf's 24-item Disturbance Due to Hospital Noise Scale and 5-point items for other environmental stress (ie, bed, lights) and personal stress (ie, pain, anxiety). Sleep was evaluated with the Verran and Snyder-Halpern Sleep Scale. RESULTS: Hierarchical multiple regression led to a multiple R of 0.435 (P <.01). An interaction term, subjective noise stress x subjective bed stress x subjective pain x subjective anxiety accounted for a significant amount of sleep variance (12%, F = 13.63, P =.000). Subjective bed stress x subjective pain accounted for an additional 5% (F = 6.4, P =.013). CONCLUSIONS: Studies using research designs that assess relationships between multiple patient stress variable interactions and sleep or other stress-related outcomes may produce more accurate results than studies on the independent effects of different types of stress.

Hospital noise pollution: an environmental stress model to guide research and clinical interventions.

Hospital noise pollution: an environmental stress model to guide research and clinical interventions This commentary provides an expanded environmental stress model. Conceptual relationships between ambient stressors, ambient stress, and health are detailed. A three-part intervention, enhancement of person-environment compatibility, is specified. Details are provided on how this approach to reducing environmental pollution/hazards and sustaining these changes may be influenced by sociopolitical values, technological advances, and motivation for control over hazards. Personal variables thought to mediate the impact of environmental stress on health, including intrinsic sensitivity to specific hazards, personality, restricted capacities, other stress, culture, personal preferences, stage of life, gender, and perceived social support, are highlighted. Research results on the stress and health effects of hospital noise on patients and nurses are summarized to provide support for the model. Future directions for research are recommended. Implications of the model for nursing, including an environmental activist role in an interdisciplinary effort to plan and implement noise abatement interventions, are described.

Effects of critical care unit noise on the subjective quality of sleep.

Nurse researchers have provided evidence that hospital critical care unit (CCU) noise may put patients at risk for sleep problems. Technological advances in this setting have been described as contributing to this problem. Although data on the negative effects of CCU noise on physiological sleep are available, less attention has been given to self-reports of the subjective quality of sleep following exposure to this stressor. This study hypothesized that subjects exposed to CCU sound levels would report poorer subjective sleep than subjects in a quieter environment. Sixty female subjects, attempting to sleep overnight in a laboratory, were randomly assigned to an experimental group, where they heard an audiotape recording of CCU sounds throughout the night, or to a quiet group where the audiotape recording of CCU sounds was withheld. A self-rating questionnaire was used to assess subjective sleep. The noise condition subjects reported taking longer to fall asleep, less time sleeping, more awakenings, poorer quality of sleep compared to home, as well as fewer positive and more negative adjectives descriptive of sleep. Self-reports of the time spent sleeping and the number of negative adjectives descriptive of sleep yielded the greatest number of significant correlations with scores for the other measures of sleep, indicating that these measures may be more accurate. Data on the quality of dreams yielded no difference between groups. The results provide support for the hypothesis that CCU sound levels impact negatively on subjective sleep. It was recommended, now that CCU sound levels were isolated in the laboratory as a potential stressor, that future research should attempt to replicate this study in a hospital CCU.

Personality hardiness, work-related stress, and health in hospital nurses.

Personality hardiness is a set of beliefs about oneself and the world one lives in. Hardier persons take control of their lives, believe that commitment to goals will result in positive outcomes, and perceive daily stressors as challenges. Hardiness has been linked with less stress and fewer health problems among various occupational groups. This study found that among 237 hospital nurses, work-related stress and emotional exhaustion were associated with greater health problems in the form of anxiety, depression, and somatic complaints. Hardier nurses reported less work-related stress, less emotional exhaustion, and less anxiety, depression, and somatization. This article discusses considerations for strengthening future studies concerned with the relationships between personality hardiness, work-related stress, and health in nurses.

Theoretical considerations for research on environmental stress and health.

Research on hospital noise may have implications for the usefulness of stress theory as a framework for the study of environmental stress and stress-related health outcomes. In this article, the results of hospital noise research are described. It is argued that noise-induced stress in hospitals is largely uncontrollable by individual coping and that stress theory may therefore need to be supplemented for the reduction of reactivity. Three concepts are proposed for this purpose. Primary among these is an intervention concept--enhancement of person-environment compatibility. Others are ongoing societal and technological development, and intrinsic sensitivity to specific stressors in the environment. Future research should attempt to reveal whether these concepts are consistently effective in the management of hospital noise and other environmental stressors.

Critical care unit noise and rapid eye movement (REM) sleep.

OBJECTIVE: To determine if Critical Care Unit (CCU) sound levels suppress rapid eye movement (REM) sleep. DESIGN: Posttest-only control group experimental design. SETTING: Sleep laboratory located in a university neurologic institute. SUBJECTS: Seventy paid ($40) women who had no hearing or sleep problems. PROCEDURES: Subjects were randomly assigned to a noise or quiet (control) group while attempting to sleep overnight in the laboratory. Noise-condition subjects heard an audiotape recording of CCU nighttime sounds. The audiotape recording was withheld from the control group. RESULTS: Subjects in the noise condition showed poorer REM sleep on seven of 10 measures. These included REM activity and shorter REM durations throughout the night and during the first and second halves of the night as well as a longer interval between the first and second REM cycles. The majority of the t test results were significant at the 0.001 level or better. CONCLUSIONS: Although generalization of the results to CCU patients is limited (because of the use of laboratory subjects), the results provided convincing support for a causal relationship between CCU sound levels and suppression of REM sleep.

Effects of personal control over hospital noise on sleep.

Critical Care Unit (CCU) sound levels, subjective stress due to noise, and sleep were studied in 105 female volunteers in a simulated hospital environment. Subjects were randomly assigned to instruction in personal control over noise via the availability of a sound conditioner, no instruction in personal control over noise, or quiet conditions. Subjects in the two noise conditions heard audiotape-recorded CCU nighttime sounds while attempting to sleep overnight in the laboratory. The intervention did not facilitate better sleep as measured by polysomnograph equipment and self-report. However, the results provided strong support for a causal relationship between CCU sounds and poorer sleep. When compared to the quiet condition, subjects in the noise conditions had poorer sleep efficiency; more difficulty falling and staying asleep; more difficulty progressing from one stage of sleep to the next; more intrasleep awakenings; spent less time in Rapid Eye Movement sleep; and poorer sleep via self-report (all ps less than .03). As predicted, scores for subjective stress due to CCU sounds yielded significant relationships with 9 of 16 measures of sleep (all ps less than .01). Hierarchical multiple regressions showed that 13% (p less than .001) and close to 6% (p less than .05) of the variance in sleep efficiency was accounted for by CCU sound levels and noise-induced subjective stress, respectively. Thirty-eight percent (p less than .001) of the variance in Rapid Eye Movement sleep was accounted for by CCU sound levels.

Stress effects of personal control over hospital noise.

Hospital critical care unit (CCU) sounds, instruction in personal control over noise, and stress were studied in 105 female volunteers attempting to sleep overnight in a simulated hospital environment. Subjects were randomly assigned to three groups--instruction in personal control over noise, no instruction in personal control over noise, or a quiet condition. The two noise conditions heard audiotaped recorded playback of CCU nighttime sounds. The subjects with instruction in personal control received directions for using a sound conditioner to block out unwanted sounds. This intervention failed to result in less stress. The results of group comparisons provided strong support for a causal relationship between CCU sounds and greater subjective stress (p less than .000) but not for physiological stress measured by urinary epinephrine. As predicted, scores for sensitivity of the person to noise were positively correlated with scores for noise-induced subjective stress (r = .226, p less than .05). Hierarchical multiple regression revealed that CCU sound levels independently accounted for 54% (p less than .001) and sensitivity to noise for 5% (p less than .01) of the variance in subjective stress.

Increasing the validity of research results with a blend of laboratory and clinical strategies.

Some nursing research problems may benefit from studies that combine laboratory and clinical research settings. Examples of studies that use a blend of laboratory and clinical components are provided. Traditional laboratory, clinical, and combined laboratory-clinical research settings are discussed in terms of their relative potential for yielding valid results.

Personality hardiness, occupational stress, and burnout in critical care nurses.

Personality hardiness, occupational stress, and burnout were investigated in 100 critical care nurses. Hardiness was predictive of occupational stress and burnout. Hierarchical multiple regressions revealed that one of the three dimensions of hardiness, commitment to work, was the only variable to account for significant amounts of variance (up to 24%) across three of four measures of burnout. The study did not provide support for the stress buffering effect of hardiness. That is, an interaction term, hardiness x occupational stress, was not convincingly predictive of burnout in nurses. The findings are discussed in terms of other research on burnout in critical care nurses and recent issues on the conceptualization of hardiness.

Noise-induced stress as a predictor of burnout in critical care nurses.

In this study we found that, for 100 critical care nurses, noise-induced occupational stress was positively related to burnout as measured by Jones's Staff Burnout Scale for Health Professionals (r = 0.369, p less than 0.001) and the emotional exhaustion subscale of Maslach's Burnout Inventory (r = 0.300, p less than 0.01). Hierarchical multiple regressions confirmed these results once variance in burnout linked with life stressors and other occupational stressors was accounted for. Furthermore, an interaction term, noise-induced stress X intrinsic sensitivity to noise in the person, did not account for significant variance in burnout once independent variance linked with noise-induced stress was identified. That is, nurses with intrinsic sensitivity to noise were no more at risk for burnout linked with noise-induced stress than were less sensitive nurses. This result is discussed as evidence that there are exceptionally high levels of noise in critical care units. The critical care unit noises that are most distressing to nurses are identified and discussed in terms of stress theory.

Interrater reliability decline under covert assessment.

This article highlighted representative studies on a methodological problem that may generalize to other observational methods and circumstances. A number of strategies have been suggested to combat this problem. Despite the need for additional research on this methodological problem and the remedial tactics discussed here, studies that deal with interrater reliability decline will surely be evaluated as more credible than those that overlook the problem.