Unique and interactive effects of emotion regulation difficulties and perceived stress on COVID-19 traumatic stress, anxiety, and safety behavior use: A four-year prospective study

Given that emotion regulation difficulties confer risk for poor responses to stress, they may predict who is at risk for adverse psychological reactions to major, chronic stressors such as the COVID-19 pandemic. Specific adverse reactions to the pandemic may include more severe traumatic stress, anxiety, and excessive safety behavior use (i.e., hand washing). While emotion regulation difficulties may be a diathesis for adverse reactions to chronic stressors, the context(s) by which they may confer elevated risk is unclear. Accordingly, the present longitudinal study examined the interaction between pre-pandemic emotion regulation difficulties and early pandemic perceived stress in predicting subsequent COVID-related traumatic stress, anxiety, and safety behavior use over 32 weeks of the pandemic. Community adults (N = 145) who completed a measure of emotion regulation in 2016 as part of a larger study were recontacted at the start of the pandemic (March 2020) and assessed every two weeks for 32 weeks. Consistent with a diathesis-stress model, the interaction between difficulties in emotion regulation and perceived stress was significant in predicting COVID-19 anxiety (p = 0.003, d = 0.52) such that at high, but not low, levels of perceived stress, difficulties in emotion regulation in 2016 significantly predicted higher COVID-19 anxiety in 2020. The interaction between difficulties in emotion regulation in 2016 and perceived stress early in 2020 approached significance in predicting COVID-19 traumatic stress (p = 0.073, d = 0.31) and safety behavior use (p = 0.069, d = 0.31). These findings highlight that current perceived stress is an important context that potentiates the effects of preexisting emotion regulation difficulties on the emergence of anxiety-related symptoms during COVID-19, which has important implications for diathesis-stress models of adverse reactions to chronic stressors.

Chronotype and Affective Response to Sleep Restriction and Subsequent Sleep Deprivation

Prior research indicates that sleep restriction, sleep deprivation, and circadian misalignment diminish positive affect, whereas effects on negative affect are inconsistent. One potential factor that may influence an individual's affective response to sleep restriction, sleep deprivation, and circadian misalignment is chronotype. Later chronotypes generally report higher negative affect and lower positive affect under typical sleep conditions; however, there is mixed evidence for an influence of chronotype on affective responses to sleep restriction and sleep deprivation. The present study examined the effect of chronotype on positive and negative affect during sleep restriction and subsequent total sleep deprivation. Sixteen healthy adults (Mage = 28.2 years, SDage = 11.6 years) were classified as earlier or later chronotypes using multiple chronotype definitions: morningness-eveningness (MEQ), mid-sleep on free days corrected (MSFsc), habitual mid-sleep timing, dim light melatonin onset (DLMO), and phase relationship between DLMO and bedtime. Participants completed a 10-day protocol with one night of sleep restriction and subsequent 28 h total sleep deprivation. Affect was assessed hourly during scheduled wakefulness with the Positive and Negative Affect Schedule (PANAS). Data were analyzed with mixed-model analyses of variance (ANOVAs). During sleep restriction and subsequent sleep deprivation, positive affect decreased and negative affect increased. Across all chronotype measures, relatively later chronotypes demonstrated vulnerability to increased negative affect during sleep loss. The influence of chronotype on positive affect during sleep loss varied by chronotype measure. These findings suggest later chronotypes are more vulnerable to affective impairments during sleep loss and circadian misalignment, even when late chronotype is not extreme.

Distribution of dim light melatonin offset (DLMOff) and phase relationship to waketime in healthy adults and associations with chronotype

OBJECTIVES

Dim light melatonin onset, or the rise in melatonin levels representing the beginning of the biological night, is the gold standard indicator of circadian phase. Considerably less is known about dim light melatonin offset, or the decrease in melatonin to low daytime levels representing the end of the biological night. In the context of insufficient sleep, morning circadian misalignment, or energy intake after waketime but before dim light melatonin offset, is linked to impaired insulin sensitivity, suggesting the need to characterize dim light melatonin offset and identify risk for morning circadian misalignment.

METHODS

We examined the distributions of dim light melatonin offset clock hour and the phase relationship between dim light melatonin offset and waketime, and associations between dim light melatonin offset, phase relationship, and chronotype in healthy adults (N = 62) who completed baseline protocols measuring components of the circadian melatonin rhythm and chronotype.

RESULTS

74.4% demonstrated dim light melatonin offset after waketime, indicating most healthy adults wake up before the end of biological night. Later chronotype (morningness-eveningness, mid-sleep on free days corrected, and average mid-sleep) was associated with later dim light melatonin offset clock hour. Later chronotype was also associated with a larger, positive phase relationship between dim light melatonin offset and waketime, except for morningness-eveningness.

CONCLUSIONS

These findings suggest morning circadian misalignment risk among healthy adults, which would not be detected if only dim light melatonin onset were assessed. Chronotype measured by sleep timing may better predict this risk in healthy adults keeping a consistent sleep schedule than morningness-eveningness preferences. Additional research is needed to develop circadian biomarkers to predict dim light melatonin offset and evaluate appropriate dim light melatonin offset timing to promote health.

Psychometric properties of a daily obsessive-compulsive symptom scale for ecological momentary assessment

Despite growing interest in ecological momentary assessment (EMA) in psychopathology and clinical observation of day-to-day fluctuations in obsessive-compulsive disorder (OCD) symptoms, there is not a standardized EMA measure of such symptoms that can guide systematic research. In the absence of such a measure, prior EMA research in OCD has utilized heterogeneous approaches to sampling momentary and daily OCD symptoms, which limits the ability to compare results between studies. The present study sought to examine the psychometric properties of a daily OCD symptom (d-OCS) measure that assesses common OCD symptom themes (e.g., contamination, checking, intrusive thoughts) in a sample of adults with OCD (n = 20), psychiatric controls (n = 27), and healthy controls (n = 27). Participants completed the d-OCS 3 times per day for 1 week. The d-OCS distinguished those with OCD from psychiatric controls and healthy controls. The d-OCS demonstrated good internal consistency, adequate test-retest reliability, and good convergent validity. These findings offer initial psychometric support for the use of the d-OCS in EMA research examining day-to-day fluctuations in symptoms of OCD. Additional investigation is needed to examine the discriminant validity of the d-OCS and generalize these findings to more diverse samples.

Subjective Sleep Disturbances in Sexual Assault Survivors: Associations With Trauma and Posttraumatic Stress Disorder Symptom Severity

Prior work implicates sleep disturbance in the development and maintenance of posttraumatic stress disorder (PTSD). However, the majority of this literature has focused on combat veteran men, and limited work has examined links between sleep disturbance and PTSD symptoms in sexual assault survivors. This is a notable gap in the literature, as sexual trauma is disproportionately likely to result in PTSD and is more common in women. We sought to examine the relations between subjective sleep disturbance, sexual assault severity, and PTSD symptoms in a sample of sexual assault survivors with PTSD (PTSD+), without PTSD (PTSD-), and healthy controls. The sample (N = 60) completed the Insomnia Severity Index and prospectively monitored their sleep for 1 week using the Consensus Sleep Diary. The sexual assault survivors also completed the Sexual Experiences Survey and PTSD Checklist-5. Results of group comparisons found that the PTSD+ group reported significantly higher insomnia symptoms, longer sleep onset latency, more nocturnal awakenings, and lower sleep quality compared to the healthy control group and higher insomnia symptoms compared to the PTSD- group. Results of regression analyses in the sexual assault survivors found that insomnia symptoms and number of nocturnal awakenings were significantly associated with higher PTSD symptoms, and sexual assault severity was significantly associated with higher insomnia symptoms, longer sleep onset latency, and lower sleep quality. These findings highlight specific features of sleep disturbance that are linked to trauma and PTSD symptom severity among sexual assault survivors.

Examining sleep disturbance components as near-term predictors of suicide ideation in daily life

Suicide ideation emerges and fluctuates over short timeframes (minutes, hours, days); however, near-term predictors of such fluctuations have not been well-elucidated. Sleep disturbance is a distal suicide risk factor, but less work has examined whether daily sleep disturbance predicts near-term changes in suicide ideation. We examined subjective sleep disturbance components as predictors of passive and active suicide ideation at the within-person (i.e., day-to-day changes within individuals relative to their own mean) and between-persons (individual differences relative to the sample mean) levels. A transdiagnostic sample of 102 at-risk young adults ages 18-35 completed a 21-day ecological momentary assessment protocol, during which they reported on sleep and passive and active suicide ideation. At the within-persons level, nightmares, sleep quality, and wake after sleep onset predicted passive suicide ideation, and sleep quality and wake after sleep onset predicted active suicide ideation. At the between-persons level, nightmares, sleep onset latency, and sleep quality were associated with passive suicide ideation, and sleep onset latency was associated with active suicide ideation. In contrast, suicide ideation did not predict subsequent sleep at the within-person level. Specific sleep disturbance components are near-term predictors of intraindividual increases in suicide ideation and may hold promise for suicide prevention and intervention.

Linking repetitive negative thinking and insomnia symptoms: A longitudinal trait-state model

Sleep disturbance is highly debilitating, and an abundance of research suggests that repetitive negative thinking (i.e., rumination, worry) may contribute to the development and maintenance of maladaptive sleep patterns, such as insomnia symptoms. Although repetitive negative thinking is often conceptualized as a 'trait' risk factor for anxiety-related disorders, it is unclear if it consists of time-varying (TV) or state-like features versus time-invariant (TI) or trait-like characteristics. Furthermore, it is unclear if it is the TV or TI components of repetitive negative thinking that contribute to insomnia symptoms that is commonly observed in anxiety-related disorders. In a 6-wave, 5-month longitudinal study, community participants (N = 1219) completed measures of rumination, worry, transdiagnostic repetitive negative thinking, and insomnia symptoms. A latent variable (trait-state-occasion) model was applied to the measures of repetitive negative thinking. The results showed that although estimates of TI factor variance and TV factor variance were both significant for latent repetitive negative thinking, worry, and rumination, the proportion of TI factor variance (0.82-0.89) was greater than the amount of TV factor variance (0.11-0.19). Although TV factor stability was statistically significant for latent repetitive negative thinking, rumination, and worry, the magnitude of the coefficients was small. Furthermore, regression weights for the latent repetitive negative thinking, rumination, and worry TI factor were significant and larger than those for the TV factor in predicting insomnia symptoms at each of the six time points. These findings suggest that repetitive negative thinking is largely TI, and it is this TI component that contributes to insomnia symptoms. Implications for conceptualizations of repetitive negative thinking as a predisposing and perpetuating factor in insomnia for anxiety and related disorders are discussed.

The role of insufficient sleep and circadian misalignment in obesity

Traditional risk factors for obesity and the metabolic syndrome, such as excess energy intake and lack of physical activity, cannot fully explain the high prevalence of these conditions. Insufficient sleep and circadian misalignment predispose individuals to poor metabolic health and promote weight gain and have received increased research attention in the past 10 years. Insufficient sleep is defined as sleeping less than recommended for health benefits, whereas circadian misalignment is defined as wakefulness and food intake occurring when the internal circadian system is promoting sleep. This Review discusses the impact of insufficient sleep and circadian misalignment in humans on appetite hormones (focusing on ghrelin, leptin and peptide-YY), energy expenditure, food intake and choice, and risk of obesity. Some potential strategies to reduce the adverse effects of sleep disruption on metabolic health are provided and future research priorities are highlighted. Millions of individuals worldwide do not obtain sufficient sleep for healthy metabolic functions. Furthermore, modern working patterns, lifestyles and technologies are often not conducive to adequate sleep at times when the internal physiological clock is promoting it (for example, late-night screen time, shift work and nocturnal social activities). Efforts are needed to highlight the importance of optimal sleep and circadian health in the maintenance of metabolic health and body weight regulation.

Linking self-disgust, negative affect, and PTSD in sexual assault: An ecological momentary assessment approach

OBJECTIVE

Although self-disgust has been implicated in sexual assault-related posttraumatic stress disorder (PTSD), empirical evidence of this association is limited.

METHOD

Participants with sexual assault-related PTSD (n = 19), sexual assault without PTSD (n = 20), and healthy controls (n = 21) completed "trait" measures of disgust proneness, self-disgust, and negative affect (NA; i.e., anxiety and depression). An ecological momentary assessment approach was also employed, where participants reported "state" levels of PTSD symptoms, self-disgust, and NA in the morning, afternoon, and evening for 1 week.

RESULTS

Those with PTSD reported more trait disgust proneness, self-disgust, and NA than those who experienced sexual assault without PTSD and controls. However, those experiencing sexual assault without PTSD and controls did not differ from each other. Participants with a history of sexual assault also experienced higher self-disgust and NA during the week than controls. Those with higher PTSD symptoms during the week also experienced more self-disgust and NA. Similarly, changes in PTSD symptoms were associated with changes in self-disgust and NA during the week. Although a temporal association was found where NA predicted subsequent PTSD symptoms (and vice versa) during the week, a temporal link between self-disgust and PTSD symptoms (or vice versa) was not found.

CONCLUSIONS

These findings suggest that the link between self-disgust and sexual assault-related PTSD is more correlational than causal. The implications of these findings for understanding how trait and state self-disgust fits within the broader emotional network of sexual assault-related PTSD are discussed. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Delayed circadian rhythms and insomnia symptoms in obsessive-compulsive disorder

BACKGROUND

Accumulating evidence implicates sleep and circadian rhythm disturbance in obsessive-compulsive disorder (OCD). However, a multimethod characterization of sleep and circadian rhythms in OCD, their association with symptom severity, and the functional relationship between these variables is lacking.

METHODS

The present study measured multiple indicators of sleep and circadian rhythms in a sample of adults with OCD, adults without OCD, and healthy controls (n = 74). Participants completed measures of morningness-eveningness, delayed sleep-wake phase disorder (DSWPD), insomnia symptoms, and OCD symptoms, as well as one week of sleep monitoring via a sleep diary and actigraphy.

RESULTS

Delayed circadian rhythms (higher eveningness, later mid-sleep timing, and higher rates of DSWPD) and higher insomnia symptoms were observed in those with OCD compared to healthy controls, as well as associations between delayed circadian rhythms and insomnia symptoms and OCD symptom severity across the full sample. Further, insomnia symptoms mediated the relationship between delayed circadian rhythms and OCD symptoms. In contrast, there were no links between total sleep time or sleep quality and OCD.

LIMITATIONS

Data collection during COVID-19 pandemic, correlational data, no physiological measure of circadian rhythms.

CONCLUSIONS

These findings highlight a robust association between delayed circadian rhythms and OCD and suggest insomnia symptoms may be one mechanism in this relationship. Sleep and circadian rhythm disturbance may be novel targets for OCD treatment.

Longitudinal trajectories of coronavirus anxiety and health behavior use before and after the U.S. 2020 presidential election: The effects of political orientation

Although heightened anxiety and health behavior use (i.e., masking, hand washing) may be viewed as an adaptive response to the coronavirus (COVID-19) pandemic, it is unclear how the politicization of the pandemic has influenced the trajectory of such responses. Accordingly, the present study examined differences between those that identify as more conservative or liberal in the trajectory of anxiety and health behaviors during the pandemic. This study also examines shifts in this trajectory before and after the presidential election. As part of a larger study, participants (N = 374) completed a symptom survey starting on May 27, 2020 every 2 weeks for a total of 15 timepoints over 30 weeks. The findings showed that more conservative participants reported lower levels of COVID-19 anxiety and less health behavior use compared to more liberal participants. In fact, anxiety levels increased slightly for more liberal participants and decreased slightly for more conservative participants during the pre-election time frame. Health behavior use also decreased more rapidly for conservative participants than for liberal participants during the pre-election time frame. However, COVID-19 anxiety and health behavior use rose sharply and similarly for both liberal and conservative individuals after the election. Importantly, these patterns were independent of state level variability in COVID-19 positivity and death rates. Subsequent analysis also revealed significant relations between COVID-19 anxiety and health behavior use that was slightly stronger among conservatives. Implications of these findings for navigating the influence of political ideology on anxiety-related responses during a public health emergency like the COVID-19 pandemic are discussed.

The effects of worry proneness on diurnal anxiety: An ecological momentary assessment approach

Existing theoretical models and empirical evidence suggest that worry proneness is associated with anxious responding. However, it is unknown how worry proneness may influence the experience of anxiety throughout the day. The present study addresses this gap in the literature by employing an ecological momentary assessment design to examine the impact of worry proneness on diurnal changes in anxiety reported in the morning, afternoon, and evening for one week in a sample of unselected adults (N = 136). Results indicated a significant reduction in anxiety from morning to evening. Further, this effect was moderated by worry proneness, such that a diurnal decline in anxiety was detectable among those with low and moderate levels of worry proneness, whereas those high in worry proneness reported increased momentary anxiety which was sustained throughout the day. These results replicate previous studies indicating anxiety is highest in the morning and lowest in the evening. Further, these findings suggest that worry proneness may override normative diurnal changes in anxiety and thereby maintain anxiety at elevated and consistent levels. The implications of these findings for the development and treatment of disorders characterized by excessive worry are discussed.

Sleep in a pandemic: Implications of COVID-19 for sleep through the lens of the 3P model of insomnia

The coronavirus disease 2019 (COVID-19) pandemic has fundamentally altered daily life across the globe, and the stress associated with these changes is likely to impact sleep. Sleep is critical for physical and mental health; thus, understanding the factors that may contribute to poor sleep during the pandemic represents a first step in identifying behavioral health targets for intervention efforts during and after the pandemic. This review first summarizes the developing research on sleep during the pandemic. The impact of the pandemic on sleep is then examined through the lens of the 3P model of insomnia by proposing pandemic-specific predisposing, precipitating, and perpetuating factors. The potential consequences of sleep disturbance on physical and mental health conditions most relevant to the pandemic are also reviewed. Finally, recommendations for reducing or eliminating pandemic-specific perpetuating factors are detailed, highlighting the potential utility of behavioral sleep medicine interventions in the integration of behavioral health responses and public health initiatives during and after the pandemic. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Eveningness Predicts Negative Affect Following Sleep Restriction

Although considerable research has shown that sleep loss results in decreased positive affect, findings regarding change in negative affect are inconsistent. Such inconsistency may be due in part to variability in individual difference factors, such as chronotype, which is associated with both sleep and affective outcomes. Chronotype represents the tendency to be a morning- or evening-type person and is underpinned by the timing of circadian processes linked to sleep and mental health. The present study examined the predictive effect of chronotype above and beyond that of depression on affective response to sleep restriction in a sample of healthy sleeping adults (n = 73). Participants completed measures of chronotype and depression at baseline and measures of positive and negative affect before and after one night of sleep restriction (4 hours between 4 a.m. and 8 a.m.). Results indicate a large, significant decrease in positive affect following sleep restriction, but no statistically significant change in negative affect. Subsequent analyses showed that chronotype predicted affective response to sleep restriction, such that eveningness predicted a medium, significant increase in negative affect following sleep restriction, controlling for depression-however, there was no association between chronotype and change in positive affect in response to sleep restriction. These findings highlight a differential effect of sleep loss on positive and negative affect and suggest that evening chronotype may confer a distinct vulnerability for increased negative affect following sleep loss.

Linking insomnia and OCD symptoms during the coronavirus pandemic: Examination of prospective associations

There is considerable concern in the mental health community about the psychological consequences of the coronavirus pandemic and who may be most vulnerable. Obsessive-compulsive disorder (OCD) symptoms may be particularly sensitive to the context of the pandemic. Previous research suggests insomnia symptoms may contribute to increased OCD symptoms over time, particularly during times of stress, such as the pandemic. The present study examined pre-coronavirus outbreak insomnia symptoms as a predictor of post-coronavirus outbreak OCD symptoms in a sample of community adults who completed a 2016 survey study and were re-contacted on April 1, 2020 (N = 369). Results revealed a small significant increase in OCD symptoms following the coronavirus outbreak and a small significant decrease in insomnia symptoms. Pre-coronavirus outbreak insomnia symptoms significantly predicted increases in post-coronavirus outbreak OCD symptoms. Similar results were found for specific OCD symptom facets with the exception of washing and hoarding symptoms, which were unrelated to pre-coronavirus insomnia symptoms. There was no evidence for a reverse effect of prior OCD symptoms on insomnia symptoms during the pandemic. These findings suggest those with insomnia symptoms prior to the coronavirus pandemic may be vulnerable to increases in some OCD symptoms during the pandemic. The implications for preventing adverse psychological responses during the coronavirus pandemic are discussed.

Pre-pandemic disgust proneness predicts increased coronavirus anxiety and safety behaviors: Evidence for a diathesis-stress model

Although health anxiety and corresponding safety behaviors can facilitate disease transmission avoidance, they can be maladaptive in excess, including during the coronavirus pandemic. Disgust proneness (i.e., tendency to experience and be sensitive to disgust) is one factor that may predict elevated coronavirus anxiety and safety behaviors during the pandemic, given the role of disgust in avoiding disease transmission. The present study examined the relations between pre-pandemic disgust proneness and coronavirus anxiety and safety behaviors in community adults who completed a 2016 study and were re-contacted on 4/1/2020 (N = 360). Interactions between pre-pandemic disgust proneness and current perceived stress were tested to examine a diathesis-stress model of the role of disgust proneness in anxiety response to the pandemic. Increased pre-pandemic disgust proneness predicted increased coronavirus anxiety and safety behaviors, controlling for number of COVID-19 cases by state. Consistent with a diathesis-stress model, current perceived stress moderated this effect, such that highest coronavirus anxiety and safety behaviors were reported by those with high disgust proneness and high stress. Trait disgust proneness may be a vulnerability factor for anxiety responses to the coronavirus pandemic, particularly among individuals experiencing high stress. Assessing disgust proneness and current stress may facilitate targeted anxiety intervention during the pandemic.

Disgust regulation between menstrual cycle phases: Differential effects of emotional suppression and reappraisal

BACKGROUND AND OBJECTIVE

Immunosuppression is characteristic of the luteal phase of the menstrual cycle and is accompanied by an adaptive disgust response to reduce contact with pathogens. However, research has not examined the effects of emotion regulation on disgust during the menstrual cycle. Accordingly, the present study examines the effect of suppression and reappraisal on disgust during the luteal and follicular phases of the menstrual cycle.

METHOD

Menstrual cycle phase was estimated in a sample of naturally cycling women (n = 73), and those in the follicular or luteal phase were assigned to suppress or reappraise disgust while watching a disgust-inducing video. Physiological arousal during the video and avoidance of disgust cues in a public restroom after the video were also assessed.

RESULTS

No differences were observed in self-reported disgust to the video between those who suppressed and those who reappraised in the luteal phase. However, women in the follicular phase who suppressed reported less disgust than those who reappraised. The emotion regulation strategies did not influence physiology during the video or avoidance after the video as a function of menstrual cycle phase.

LIMITATIONS

Hormone assay data was not collected to confirm menstrual cycle phase and a relatively small sample of naturally cycling women was used.

CONCLUSIONS

Suppression may be a more effective strategy than reappraisal for reducing verbal disgust in the follicular phase but not in the luteal phase. The implications of these findings for the treatment of disgust-based disorders among women are discussed.

0283 Differential Impact of Chronotype on Positive and Negative Affect Following Sleep Restriction

Introduction

Previous research indicates sleep deprivation significantly decreases positive affect, while negative affect is often unaffected (Reddy et al., 2017; Schwarz et al., 2019). However, it is unclear whether individual difference factors predict a differential emotional response to sleep loss. Though one study found chronotype predicts decreased positive affect following sleep loss in adolescents (Dagys et al., 2012), the effect of chronotype on emotional response to sleep loss in adults remains unknown.

Methods

The present study addressed this limitation by examining whether chronotype predicts changes in positive and negative affect following partial sleep restriction. Healthy sleeping adults (N=113; Insomnia Severity Index<8) completed the Morningness-Eveningness Questionnaire (Horne & Ostberg, 1976) on day 1, and were instructed to sleep normally on night 1. On the evening of day 2, participants completed the Positive and Negative Affect Schedule (PANAS; MacKinnon et al., 1999) to sample baseline daily emotions. On night 2, sleep was restricted to 4-8am. On day 3, participants completed the PANAS post-sleep restriction. Compliance was verified with actigraphy (n=22 excluded for noncompliance), and response to the sleep restriction procedure was checked with the Stanford Sleepiness Scale (Hoddes, Dement, & Zarcone, 1972; n=18 excluded for nonresponse).

Results

Results suggest a significant decrease in positive affect from pre-sleep restriction (M=15.63, SD=4.09) to post-sleep restriction (M=11.08, SD=3.93), t(71)=10.33, p<.01, and a trend decrease in negative affect from pre-sleep restriction (M=7.68, SD=3.62) to post-sleep restriction (M=6.90, SD=2.41), t(71)=1.60, p=07. Chronotype was significantly associated with post-sleep restriction negative affect, controlling for baseline negative affect (β=-.42, p<.01), such that eveningness was associated with increased negative affect following sleep restriction. In contrast, chronotype was unrelated to post-sleep restriction positive affect.

Conclusion

These findings indicate that evening types may be more likely to experience emotions implicated in anxiety-related disorders following sleep loss, such as fear and nervousness.

Support

This work was supported by the National Institute of Mental Health of the National Institutes of Health [F31MH113271] and a Graduate Student Summer Research Award from Vanderbilt University. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Sleep in the anxiety-related disorders: A meta-analysis of subjective and objective research

Although sleep disturbance is implicated in psychopathology, its role in anxiety-related disorders remains unclear. The present meta-analysis characterizes sleep disturbance in anxiety-related disorders collectively and individually. Subjective measures of total sleep time and sleep continuity were included with objective measures. Results indicate a large effect for increased subjective sleep disturbance (g = 2.16), medium effects for decreased total sleep time (g = -.40) and sleep continuity (g = -.49), and a small effect for decreased sleep depth (g = -.20) in anxiety-related disorders compared to healthy controls. Each anxiety-related disorder exhibited a distinct sleep disturbance pattern, suggesting that sleep may facilitate identification of unique biopsychological underpinnings. Effects were not moderated by comorbid depression and were similar in magnitude to those found for depression. Sleep disturbances, particularly decreased sleep continuity, may be a key pathology in the anxiety-related disorders that could highlight novel etiological mechanisms and intervention targets.

Differential associations between chronotype, anxiety, and negative affect: A structural equation modeling approach

BACKGROUND

Increasing evidence implicates circadian rhythms, including chronotype, in anxiety symptoms and disorders. However, it remains unclear whether this relation is accounted for by sleep disturbance. Likewise, given overlap between anxiety and negative affect, a unique link between chronotype and anxiety remains to be established. The present study addressed these questions using a multimethod approach to determine whether there is a unique relation between chronotype and anxiety symptoms, controlling for sleep disturbance.

METHODS

Indicators of chronotype, sleep disturbance, anxiety, and negative affect were collected in a sample of adults (N = 151) using a combination of subjective and behavioral measures both within and outside the laboratory over a 9-day period. Structural equation modeling was used to examine associations between latent constructs.

RESULTS

Results revealed significant associations between sleep disturbance and both anxiety and negative affect. A significant association was found between chronotype and anxiety, over and above the effect of sleep disturbance. In contrast, the relation between chronotype and negative affect was nonsignificant after controlling for sleep disturbance.

LIMITATIONS

Unselected sample, lack of experimental manipulation, cross-sectional design.

CONCLUSIONS

These findings suggest a unique role of chronotype in anxiety and point to circadian disruption as a potential biological mechanism in anxiety-related disorders.

Prospective associations between disgust proneness and OCD symptoms: Specificity to excessive washing compulsions

Although considerable evidence has linked disgust proneness (DP) to obsessive-compulsive disorder (OCD), few studies have examined the extent to which DP predicts OCD symptoms over time. Further, it remains unclear if DP is a risk factor for the contamination subtype of OCD specifically or if it is prospectively associated with other OCD symptom subtypes. The present study sought to address these gaps in the literature with a large sample of unselected community participants (n = 497) that completed measures of DP and OCD symptoms monthly over a 6-month period. Latent growth analysis revealed that initial levels of DP were associated with higher initial level of total OCD symptoms when controlling for depression, but not the slope of change in total OCD symptoms over time. Initial levels of total OCD symptoms were also associated with higher initial levels of DP when controlling depression, but not the slope of change in DP over time. Examination of symptom specificity revealed that initial levels of DP were associated with initial levels of washing, neutralizing, obsessing, ordering, and hoarding symptoms. However, initial levels of DP were associated only with the slope of change in the washing subtype when controlling for depression such that high initial levels of DP were associated with steeper increases in washing symptoms of OCD over the 6-month period. These findings suggest that although DP may have concurrent associations with symptoms of OCD more broadly, prospective associations are specific to the contamination/washing subtype of OCD. The implications of these findings for the etiology and treatment of contamination-based OCD are discussed.

Time of day effects on the relationship between daily sleep and anxiety: An ecological momentary assessment approach

Previous research has linked sleep disturbance to anxiety. However, evidence for this relation has been inconsistent, largely limited to retrospective reports that do not account for daily variability, and silent on when the association is most pronounced. Thus, the present study utilized ecological momentary assessment (EMA) to examine the effects of daily deviations in total sleep time (TST) and person-average TST on anxiety and whether these effects varied as a function of time of day in a sample of unselected adults (N = 138). Results indicate that the amount of TST on a given night, relative to personal average TST, negatively predicted anxiety, and this relation was significant in the morning and afternoon, but not evening. In contrast, person-average TST was unrelated to average anxiety. Relations between TST and anxiety did not differ across objective (e.g., actigraphy) and subjective (e.g., sleep diary) measures. Furthermore, the pattern of results remained the same when controlling for previous day's anxiety and were not bidirectional. These findings suggest that getting less sleep than is typical for the individual predicts subsequent anxiety, and this effect is particularly strong in the morning. Average sleep duration may be less important to the experience of anxiety than deviations from that average. These findings highlight the importance of EMA to examine how and when variability in sleep confers vulnerability for anxiety symptoms.

The role of eveningness in obsessive-compulsive symptoms: Cross-sectional and prospective approaches

BACKGROUND

Eveningness may be defined as the tendency to be most active and alert during the evening. Previous research has linked eveningness with maladaptive psychological outcomes, and recent evidence has highlighted circadian dysregulation as a novel factor in psychopathology, including obsessive-compulsive disorder (OCD). However, limited research has examined the unique relationship between eveningness and OC symptoms. Two studies were conducted to thoroughly examine the links between eveningness and OC symptoms, while also considering the role of depression symptoms and sleep-related factors.

METHODS

Using a cross-sectional approach, Study 1 examined the association between eveningness and OC symptoms when controlling for depression symptoms. Study 2 then employed a prospective approach to examine the extent to which the relationship between eveningness and change in OC symptoms over 4 months is mediated by change in sleep disturbance and total sleep time when controlling for depression symptoms.

RESULTS

Results indicated that depression better accounts for the cross-sectional association between eveningness and OC symptoms. However, eveningness was found to be a more robust prospective predictor of change in OC symptoms in Study 2. Furthermore, sleep disturbance, but not total sleep time, partially mediated the relationship between eveningness and OC symptoms.

LIMITATIONS

Single-method self-report approach, unselected sample, and lack of experimental manipulation.

CONCLUSIONS

These findings suggest that eveningness may contribute to the development of OC symptoms over time, in part due to its effect on sleep disturbance. Future research examining the role of circadian dysregulation in OCD may uncover novel physiological mechanisms.

Cognitive mechanisms of disgust in the development and maintenance of psychopathology: A qualitative review and synthesis

A growing body of research has implicated disgust in various psychopathologies, especially anxiety-related disorders. Although the observed role of disgust in many disorders is robust, the mechanisms that may explain this role are unclear. Cutting-edge research in cognitive science has the potential to elucidate such mechanisms and consequently improve our understanding of how disgust contributes to the etiology and maintenance of psychopathology. In this qualitative review, we systematically assess cognitive bias mechanisms that have been linked to disgust and its disorders. This review suggests that disgust-related biases may be observed in memory, interpretation, judgment of expectancies, and attention, as well as at implicit levels. Of these cognitive domains, the most robust bias appears to be observed at the level of attention. However, reliable moderators of attentional biases for disgust have not yet been identified, and this bias has not been systematically linked to other levels of analysis. Despite these limitations, the available research indicates that attentional avoidance rather than orienting or maintenance may be the most characteristic of disgust. Attentional avoidance of disgust may have important implications for etiological and treatment models of disorders characterized by excessive disgust reactions. The implications for advancing such models are discussed in the context of a combined cognitive bias hypothesis.

Prospective Associations Between Sleep Disturbance and Repetitive Negative Thinking: The Mediating Roles of Focusing and Shifting Attentional Control

Although considerable evidence has linked sleep disturbance to symptoms of psychopathology, including repetitive negative thinking, few studies have examined how sleep disturbance may predict repetitive negative thinking over time. Further, no study to date has examined specific mechanisms that may account for this relationship. The present study sought to address these gaps in the literature by testing focusing and shifting attentional control as two potential mediators of the relationship between sleep disturbance and repetitive negative thinking over a 6-month period. A final sample of 445 unselected community participants completed measures of sleep disturbance and repetitive negative thinking at Time 1, measures of focusing and shifting attentional control 3 months later, and measures of repetitive negative thinking again 6 months later. Results revealed that focusing, but not shifting, attentional control mediated the relationship between sleep disturbance and repetitive negative thinking, specifically, worry, rumination, and obsessions. These findings provide preliminary evidence for focusing attentional control as a candidate mechanism that may explain the causal role of sleep disturbance in the development of repetitive negative thinking observed in various disorders.

Interactive effects of insomnia symptoms and trauma exposure on PTSD: Examination of symptom specificity

OBJECTIVE

Although symptoms of posttraumatic stress disorder (PTSD) are common following exposure to a traumatic event, most people who experience trauma do not develop PTSD. Thus, the identification of risk factors that may interact with trauma exposure to confer vulnerability for the development of PTSD may highlight important targets for prevention and treatment. Recent research suggests that sleep disturbance amplifies the effect of maladaptive emotional processes on PTSD symptom severity. However, no study to date has examined the impact of sleep disturbance, such as insomnia symptoms, on the relationship between trauma exposure severity and specific PTSD symptom clusters.

METHOD

The present study examined insomnia symptoms as a potential moderator of the relationship between trauma exposure severity and specific PTSD symptom clusters among combat exposed veterans (N = 72).

RESULTS

Results revealed large associations between insomnia symptoms and PTSD symptom clusters, small to moderate associations between combat trauma severity and PTSD symptom clusters, and a significant interaction between insomnia symptoms and combat exposure to predict reexperiencing, but not avoidance or arousal, symptoms of PTSD.

CONCLUSION

These findings suggest that poor sleep may be one risk context in which trauma exposure results in the development of reexperiencing symptoms of PTSD. The implications of these findings for the development and maintenance of reexperiencing symptoms of PTSD are discussed. (PsycINFO Database Record

The effects of cognitive reappraisal on conditioned disgust in contamination-based OCD: An analogue study

Experimental research has shown that conditioned disgust is resistant to extinction, which may account for the slower habituation to disgust relative to fear in contamination-based obsessive-compulsive disorder (OCD). However, few studies have examined the efficacy of interventions that may attenuate conditioned disgust responses. Studies of cognitive reappraisal have demonstrated that reinterpreting a stimulus can alter emotional responding. This technique is based on cognitive theories which suggest that anxiety disorders arise from biased cognitions; therefore, changing a person's thoughts will elicit durable changes in emotional responses. Given the demonstrated effectiveness of cognitive reappraisal, the present study examined whether cognitive reappraisal would attenuate conditioned disgust responses. We conditioned participants high in contamination fear (n=55) using images of neutral food items (conditioned stimuli; CS) paired with videos of individuals vomiting (unconditioned stimuli; US) while we obtained subjective disgust reports. After conditioning, half of the participants were randomly assigned to cognitive reappraisal training aimed at decreasing their emotional response to the US and CS, while the other half received no such training. The findings showed that cognitive reappraisal participants demonstrated a reduction in learned disgust across sessions and further benefited from extinction. These findings suggest that cognitive reappraisal may be an effective strategy for attenuating learned disgust.

Sleep Disturbance in Posttraumatic Stress Disorder: Epiphenomenon or Causal Factor?

PURPOSE OF REVIEW

The goal of this review is to integrate recent findings on sleep disturbance and PTSD, examine sleep disturbance as a causal factor in the development of PTSD, and identify future directions for research, treatment, and prevention.

RECENT FINDINGS

Recent research highlights a relationship between both objective and subjective sleep disturbance and PTSD across diverse samples. Sleep disturbance also predicts PTSD over time. Finally, treatments targeting sleep disturbance lead to decreased PTSD symptoms, while standard PTSD treatments conclude with residual sleep disturbance. Sleep disturbance may be more than a mere epiphenomenon of PTSD. Future research examining the causal role of sleep disturbance in the development of PTSD, as well as the utility of targeting sleep disturbance in prevention and treatment, is necessary to fully understand the likely bidirectional relationship between sleep disturbance and PTSD.

A systematic review of sleep disturbance in anxiety and related disorders

Recent research suggests that sleep disturbance may be a transdiagnostic process, and there is increasing interest in examining how sleep disturbance may contribute to anxiety and related disorders. The current review summarizes and synthesizes the extant research assessing sleep in anxiety and related disorders. The findings suggest that sleep disturbance exacerbates symptom severity in the majority of anxiety and related disorders. However, the nature of sleep disturbance often varies as a function of objective versus subjective assessment. Although sleep disturbance is a correlate of most anxiety and related disorders, a causal role for sleep disturbance is less clear. A model of potential mechanisms by which sleep disturbance may confer risk for the development of anxiety and related disorders is discussed. Future research integrating findings from basic sleep research with current knowledge of anxiety and related disorders may facilitate the development of novel treatments for comorbid sleep disturbance and clinical anxiety.

Substrate specificity of the integral membrane protease OmpT determined by spatially addressed peptide libraries

Escherichia coli outer membrane protease T (OmpT) is an endopeptidase that specifically cleaves between two consecutive basic residues. In this study we have investigated the substrate specificity of OmpT using spatially addressed SPOT peptide libraries. The peptide acetyl-Dap(dnp)-Ala-Arg/Arg-Ala-Lys(Abz)-Gly was synthesized directly onto cellulose membrane. The peptide contained the aminobenzoyl (Abz) fluorophore, which was internally quenched by the dinitrophenyl (dnp) moiety. Treatment of the SPOT membrane with the small, water-soluble protease trypsin resulted in highly fluorescent peptide SPOTs. However, no peptide cleavage was observed after incubation with detergent-solubilized OmpT, a macromolecular complex with an estimated molecular mass of 180 kDa. This problem could be solved by the introduction of a long, polar polyoxyethylene glycol linker between the membrane support and the peptide. Peptide libraries for the P(2), P(1), P(1)', and P(2)' positions in the substrate were screened with OmpT, and peptides of positive SPOTs were resynthesized and subjected to kinetic measurements in solution. The best substrate Abz-Ala-Lys-Lys-Ala-Dap(dnp)-Gly had a turnover number k(cat) of 40 s(-)(1), which is 12-fold higher than the starting substrate. Peptides containing an acidic residue at P(2) or P(2)' were not substrates for OmpT, suggesting that long-range electrostatic interactions are important for the formation of the enzyme-substrate complex. OmpT was highly selective toward L-amino acids at P(1) but was less so at P(1)' where a peptide with D-Arg at P(1)' was a competitive inhibitor (K(i) of 19 microM). An affinity chromatography resin based on these findings was developed, which allowed for the one-step purification of OmpT from a bacterial lysate. The implications of the determined consensus substrate sequence (Arg/Lys)/(Arg/Lys)-Ala for the proposed biological function of OmpT in defense against antimicrobial peptides are discussed.

Rational design of alpha-keto triglyceride analogues as inhibitors for Staphylococcus hyicus lipase

We have synthesized a series of alpha-keto triglyceride analogues as inhibitors for the lipase from Staphylococcus hyicus (SHL). Hydrolysis at positions 1 and 2 was prevented by replacement of the ester bonds by nonhydrolyzable ether, carbamoyl, or amide bonds, and an alpha-keto fatty acid was introduced at position 3. Such compounds act as competitive inhibitors of SHL. Inhibition must be caused by the presence of the alpha-keto functions, since the compounds containing an ester or a hydroxyl group in position 3 did not inhibit the enzyme. We propose that our inhibitors react with the active site Ser of the lipase, hereby mimicking the tetrahedral intermediate occurring in substrate hydrolysis. We conclude that the localization of the alpha-keto triglycerides is very important for inhibition because only those compounds which are insoluble in water are lipase inhibitors. In addition, other specific protein-inhibitor interactions, probably with the carbonyl oxygen at position 1 and/or 2, improve inhibitor binding. This makes the compounds with amide or carbamoyl groups at positions 1 and 2 better inhibitors than their ether counterparts. The inhibitory power could be improved further by replacing the oxygen at position 3 by an amido group. The resulting inhibitor 1, 2-diethylcarbamoyl-3-amido-alpha-ketododecanoylglycerol has a Ki value of 0.008 mol %, indicating that it binds approximately 125-fold tighter than the substrate. These results illustrate that effective lipase inhibitors can be designed by combining an alpha-keto group with good micellar solubility and optimal protein-inhibitor interactions.

Half-of-the-sites reactivity of outer-membrane phospholipase A against an active-site-directed inhibitor

The reaction of a novel active-site-directed phospholipase A1 inhibitor with the outer-membrane phospholipase A (OMPLA) was investigated. The inhibitor 1-p-nitrophenyl-octylphosphonate-2-tridecylcarbamoyl-3-et hanesulfonyl -amino-3-deoxy-sn-glycerol irreversibly inactivated OMPLA. The inhibition reaction did not require the cofactor calcium or an unprotonated active-site His142. The inhibition of the enzyme solubilized in hexadecylphosphocholine micelles was characterized by a rapid (t1/2 = 20 min) and complete loss of enzymatic activity, concurrent with the covalent modification of 50% of the active-site serines, as judged from the amount of p-nitrophenolate (PNP) released. Modification of the remaining 50% occurred at a much lower rate, indicative of half-of-the-sites reactivity against the inhibitor of this dimeric enzyme. Inhibition of monomeric OMPLA solubilized in hexadecyl-N,N-dimethyl-1-ammonio-3-propanesulfonate resulted in an equimolar monophasic release of PNP, concurrent with the loss of enzymatic activity (t1/2 = 14 min). The half-of-the-sites reactivity is discussed in view of the dimeric nature of this enzyme.

Identification of a calcium binding site in Staphylococcus hyicus lipase: generation of calcium-independent variants

In this study we have identified the presence of a high-affinity binding site for calcium in the lipase from Staphylococcus hyicus. By means of isothermal titration calorimetry we showed that the enzyme binds one calcium per molecule of enzyme with a dissociation constant of 55 microM. The residual activity of the apoenzyme compared to the activity in the presence of calcium ions varies from 65% at 10 degreesC to nearly zero at 40 degreesC. On the basis of primary sequence alignment with other staphylococcal lipases and the lipases from Bacillus thermocatenulatus and from Pseudomonas glumae in combination with site-directed mutagenesis, aspartates 354 and 357 could be identified as calcium ligands. Kinetic measurements with the D357E variant showed that replacement of Asp357 by a glutamate decreased the affinity for calcium ions 30-fold. Introduction of a lysine, an asparagine, or an alanine at position 357 and of a lysine or an asparagine at position 354 resulted in calcium-independent variants. Isothermal titration calorimetry confirmed the loss of calcium binding. Although the D357K, D357N, and D357A variants did not bind calcium, at room temperature they were nearly as active as wild-type lipase in the presence of calcium, but at elevated temperatures these calcium-independent lipases showed a reduced activity. Over the whole temperature range the activities of the D354K and D354N variants are significantly lower than wild-type enzyme in the presence of calcium and are comparable to the activity of the wild-type apoenzyme. Our results show that binding of calcium is important for the structural stabilization of staphylococcal lipases (and possibly other lipases) and that it is possible to engineer calcium-independent variants on the basis of limited structural homology with another lipase.

The lipase from Staphylococcus aureus. Expression in Escherichia coli, large-scale purification and comparison of substrate specificity to Staphylococcus hyicus lipase

The genes coding for the mature part of the lipases from Staphylococcus aureus NCTC8530 and Staphylococcus hyicus have been cloned and overexpressed in Escherichia coli as fusion proteins with an N-terminal hexa-histidine tag. The enzymes accumulated in the cytoplasm and were purified using sequential precipitation with protamine sulphate and ammonium sulphate, followed by metal-affinity and hydroxyapatite chromatography. The yield of pure lipase was 4.5 mg/g wet cells for S. aureus lipase and 13 mg/g for S. hyicus lipase. The purified enzymes need calcium for activity, albeit with different affinities, and a low residual activity was found in the absence of calcium. In contrast to S. hyicus lipase, not only strontium but also barium can replace calcium with full retention of activity of S. aureus lipase. Whereas S. hyicus lipase is optimally active at pH 8.5, the optimum pH for enzymatic activity for S. aureus lipase was found to be pH 6.5. The S. aureus lipase has a narrow substrate specificity: short-chain triacylglycerols and acyl esters of both p-nitrophenol and umbelliferone are readily degraded, whereas medium- and long-chain lipids, as well as phospholipids, are poor substrates. In contrast, S. hyicus lipase prefers phospholipids as substrate and hydrolyses neutral lipids irrespective of their chain length. The results are discussed in view of the large sequence similarity between both lipases.

Incorporation of an unnatural amino acid in the active site of porcine pancreatic phospholipase A2. Substitution of histidine by 1,2,4-triazole-3-alanine yields an enzyme with high activity at acidic pH

The effect of the substitution of the active site histidine 48 by the unnatural 1,2,4-triazole-3-alanine (TAA) amino acid analogue in porcine pancreas phospholipase A2 (PLA2) was studied. TAA was introduced biosynthetically using a his-auxotrophic Escherichia coli strain. To study solely the effect of the substitution of the active site histidine, two nonessential histidines (i.e. His17 and His115) were replaced by asparagines, resulting in a fully active mutant enzyme (His-PLA2). In this His-PLA2 the single histidine as position 48 was substituted by TAA with an incorporation efficiency of about 90%, giving a mixture of His-PLA2 and TAA-PLA2. Based on the charge difference at acidic pH, both forms could be separated by FPLC, allowing for the purification of TAA-PLA2 free from His-PLA2. At pH 6, TAA-PLA2 has a fivefold reduced activity compared with His-Pla2. This reduced activity paralells a reduced rate of covalent modification with p-nitrophenacyl bromide of TAA-PLA2 compared with His-PLA2. Competitive inhibition gave comparable IC50 values for WT-PLA2, His-PLA2 and TAA-PLA2. These results indicate that the reduction in activity is not caused by a different affinity for the substrate, but more likely results from a reduced kcat value in TAA-PLA2. The enzymatic activities for native and mutant PLA2s were measured at different pH values. For WT-PLA2 and His-PLA2 the activity is optimal at pH 6 and is strongly deminished at acidic pH, with no observable activity at pH 3. In contrast, TAA-PLA2 is as active at pH 3 as at pH 6. Most likely, the decrease in activity observed for WT-PLA2 and His-PLA2 is caused by the protonation of the active site His48, which is the general base involved in the activation of the nucleophilic water molecule. In TAA-PLA2, however, the active site residue TAA48 is unprotonated at both pH 3 and 6 as a result of the low pKa of TAA compared with histidine.

311C90, a new central and peripherally acting 5-HT1D receptor agonist in the acute oral treatment of migraine: a double-blind, placebo-controlled, dose-range finding study

311C90 is a novel, centrally and peripherally, acting 5-hydroxytryptamine1D receptor agonist. We investigated the efficacy and safety of 1, 5, and 25 mg of oral 311C90 in the acute treatment of migraine in a randomized, double-blind, placebo-controlled, parallel-group clinical trial involving 84 patients. The proportion of patients in whom the headache improved within 2 hours from moderate or severe to mild or no pain (primary efficacy measure) was 15% for placebo-treated patients and 27% (1 mg), 62% (5 mg), and 81% (25 mg) for patients treated with 311C90. Treatment differences compared with placebo were 12% (95% CI - 12, 37; p = 0.460) for 1 mg 311C90, 47% (CI 21, 73; p < 0.005) for 5 mg 311C90, and 66% (CI 43,89; p < 0.001) for 25 mg 311C90. Photophobia and nausea also showed improvement after 311C90. Adverse events were generally mild and transient in all treatment groups. There were no clinically significant changes in ECG recordings, blood pressure, or laboratory tests. Oral 311C90 (5 and 25 mg) is highly effective and well tolerated in the acute treatment of migraine. The response rates and treatment differences compared with placebo in this study suggest possible superiority over existing antimigraine therapies. This needs to be confirmed in formal comparative trials.

An extended binding pocket determines the polar head group specificity of porcine pancreatic phospholipase A2

Porcine pancreatic phospholipase A2 (PLA2) was studied by site-directed mutagenesis. Arg53 and/or Lys56 were replaced by a methionine (R53M or K56M, respectively) in combination with the Tyr69-->Phe (Y69F) substitution. These substitutions improved the activity on micellar and monomeric zwitterionic substrates and reduced the activity on negatively charged substrates compared to the Y69F mutant. With the neutral substrate 1,2-didodecanoyl-sn-glycerol-3-dimethyl phosphate (Lau2GroMe2P) a 20-fold increase of activity was observed for the 69F53M56M mutant, whereas this mutant showed a lower activity than native PLA2 on zwitterionic substrates. Thus the ratio Lau2GroMe2P/Lau2GroPCho has become 65 times higher for 69F53M56M compared to native phospholipase A2, illustrating that the substrate specificity has changed enormously. The methionine substitutions were also prepared in a 69F mutant in which a part of the surface loop (residues 62-66) was deleted. Also in this deletion mutant these substitutions showed a similar effect as the substitutions in the native 69F mutant. Furthermore it was shown that deletion of the loop increases the activity on micellar lecithins and negatively charged micellar substrates, but reduces the activity on Lau2GroMe2P. Therefore it can be concluded that the loop is important for the recognition of substrates. We also show that the loop plays a role in the dimerization of these proteins. Dimerization may account for the high activities observed for some mutants acting on monomeric substrate.

Cutinase from Fusarium solani pisi hydrolyzing triglyceride analogues. Effect of acyl chain length and position in the substrate molecule on activity and enantioselectivity

Triglyceride analogues were synthesized in which one of the primary acyl ester functions has been replaced by an alkyl group and the secondary acyl ester bond has been replaced by an acyl amino bond. The chain length at either position was varied, and both (R)- and (S)-enantiomers of each compound were synthesized. These pseudo triglycerides contain only one hydrolyzable ester bond, and they are ideally suited to studying the influence of the chain length at the 1-, 2-, and 3-position on lipase activity and on stereopreference. These substrates were used to characterize cutinase from Fusarium solani pisi. Our results show that the activity of cutinase is very sensitive to the length and distribution of the acyl chains and that the highest activities are found when the chains at positions 1 and 3 contain three or four carbon atoms. The enzyme preferentially hydrolyzes the (R)-enantiomers, but this preference is strongly dependent on the acyl chain length distribution, with (R) over (S) activity ratios varying from about 30 to 1. This enantioselectivity was found in three different assay systems: a mixed micellar, a reverse micellar, and a monolayer study. Our data suggest that at least two alkyl chains of the pseudo triglycerides must be fixed during hydrolysis. Therefore, these substrates were used to characterize mutants of cutinase with mutations in putative lipid binding domains. Two mutants (A85F and A85W) have increased activities. The results obtained with these mutants suggest an interaction of the acyl chain of the scissile ester bond with a surface loop, comprising residues 80-90, in the enzyme-substrate complex.

Prostate cancer. Radiation therapy for localized disease

BACKGROUND

Since 1910, a variety of radiation modalities, including radioactive isotopes, photons, and particle beams, have been used to treat prostatic cancer.

METHODS

This report focuses on external beam x-irradiation produced by medium energy linear accelerators. Between 1956 and 1990, 1119 patients have been treated with curative intent at Stanford University. Tumor doses of 70 Gy delivered at 10 Gy/wk have been safe and effective.

RESULTS

Fifteen-year survival rates ranging from 50%, equivalent to that of an age-matched cohort, for the least extensively localized tumors to 18% for the most extensive have been achieved. Survival is inversely proportional to clinical stage and histopathologic grade.

CONCLUSION

Although external beam radiation therapy has been found to be safe and effective for the treatment of prostatic cancer, improvement in results of treatment of the more advanced tumors might be achieved by combining external beam and interstitial irradiation. This would achieve a higher radiation dose within the tumor. Alternatively, the treatment can be augmented with hyperthermia or other sensitizers in order to achieve a higher biological dose.

The educational preparation and professional activities of occupational therapists

The professional activities of five groups of occupational therapists with different educational backgrounds were compared to examine the influence of education on career characteristics. Analysis of covariance, using length of professional experience as the covariate, revealed statistically significant differences in the areas of education, administration and supervision, leadership, oral presentations, publications, and research but not in clinical practice, public relations, products development, or professional recognition. The greatest differences emerged between the bachelor's, postbaccalaureate certificate, and basic master's groups and the advanced master's and other master's groups, thus supporting the association between increased education and increased professional involvement. No differences were detected between the bachelor's, certificate, and basic master's groups or between the advanced and other master's groups. The least involvement in professional activities occurred in the certificate group although the participation level for all groups was low. Although the findings highlight the important role of education in increasing therapists' involvement in professional activities, educational interventions more subtle than manipulating the entry level for practice or proliferating occupational therapy graduate programs may be needed to create a cadre of occupational therapists committed to advancing the stature of occupational therapy.

THE ROLE OF ABSCISIC ACID AND CALCIUM IN DETERMINING THE BEHAVIOUR OF ADAXIAL AND ABAXIAL STOMATA

Experiments are described which attempted to clarify the reasons for differences in stomatal opening on adaxial and abaxial epidemics. Previous studies had suggested that endogenous auxin levels might be responsible. It was found that adaxial stomata were more sensitive than abaxial stomata to externally supplied abscisic acid (ABA). It is suggested that differing endogenous concentrations of calcium ions in the upper and lower epidermes may contribute to the observed differences in sensitivity to ABA. It is further suggested that studies of stomata on isolated epidermis may represent a useful model system for examining the role of cell or tissue sensitivity in determining the responses to ABA and other hormones. Data are presented which lend support to the suggestion that calcium ions play an important part. Treatment with lanthanum ions, which block calcium channels in cell membranes, had little effect on abaxial stomata, but caused the apertures of adaxial stomata to increase considerably. The chelating agent EGTA eliminated the differential behaviour of adaxial and abaxial stomata, which clearly suggests that calcium ions have a dominant role. Experiments in which EGTA and fusicoccin were presented separately and in combination indicated that their effects were independent and additive. It is suggested that they operate at different locations, or on different processes in the guard cells.

Class of 1980

The purpose of this study was to collect and summarize comprehensive demographic data and other information about students graduating from entry-level physical therapy education programs. A survey of graduating students from 83 institutions with approved programs listed in the October 1979 issue of Physical Therapy resulted in responses from 2,280 students from 81 institutions. The findings present a description of the 2,280 respondents and profiles for male and female students and for graduates of different types of entry-level programs. This information should be useful to those involved with educational programs, the professional Association, and other individuals as they make decisions and plan educational strategies for the preparation of future physical therapists.