Fearlessness about death and suicidal ideation: Religious identity matters

INTRODUCTION

Religion is a salient aspect of patient background in treatment (The psychology of religion and coping: Theory, research, practice; Guilford Press). However, research investigating the role of religion in suicide is lacking and inconsistent (Journal of Religion and Health, 57, 2478-2499). The current study (1) clarifies the association between religious identity and fearlessness about death in a psychiatric sample and (2) tests whether religious identity moderates the association between fearlessness about death and suicidal ideation.

METHODS

Participants were 155 patients seeking treatment in a partial hospital program. Religious identity was assessed using the Identities in Treatment Scale (The Behavior Therapist). Fearlessness about death was assessed with two relevant items from the acquired capability with rehearsal for suicide scale (Psychological Assessment, 28, 1452-1464), as in prior studies (Suicide & Le-Threatening Behavior, 50, 1230-1240; Journal of Affective Disorders Reports, 12, 100492).

RESULTS

Fearlessness about death interacted with religious identity to predict suicidal ideation, b = 0.47, 95% C.I. [0.02, 0.91], p = 0.042. Conditional effects showed that greater fearlessness about death was associated with greater suicidal ideation among non-religious patients, b = -0.56, 95% C.I. [-0.88, -0.24], p = 0.001, but not in religious patients, b = -0.09, 95% C.I. [-0.41, 0.22], p = 0.559.

CONCLUSIONS

Our results suggest that fearlessness about death is a risk factor for suicidal ideation, but only among those who do not identify as religious. Results from this study inform theories of suicide and elucidate the influence of religious identity on links among suicide risk factors and suicide-related outcomes.

Non-suicidal Self-injurious Thoughts and Behaviors Among Adolescent Inpatients

Non-suicidal self-injury (NSSI) is a serious public health concern that typically onsets during early adolescence. Adolescents (N = 980, ages 12-19 years) admitted for acute, residential psychiatric treatment completed baseline clinical interviews assessing mental disorders and questionnaires measuring demographics, early life adversity, and symptom severity. Prevalence rates of NSSI for lifetime (thoughts: 78%; behaviors: 72%), past year (thoughts: 74%; behaviors: 65%), and past month (thoughts: 68%; behaviors: 51%) were high. Although effect sizes were modest, the presence of a lifetime depressive disorder, sexual abuse, and comorbidity (i.e., three or more current disorders) were significant correlates of experiencing NSSI thoughts and behaviors. Furthermore, lifetime depressive disorder, current anxiety disorder, and comorbidity were associated with a greater odds of persistent NSSI thoughts and/or behaviors. Longitudinal studies are needed to determine whether targeting these factors reduces the persistence of NSSI thoughts and behaviors.

Stress exposure in at-risk, depressed, and suicidal adolescents

BACKGROUND

Stress exposure contributes to the onset, maintenance, and recurrence of major depressive disorder (MDD) in adolescents. However, the precise stress facets (e.g. chronicity, domain) most strongly linked to outcomes at different stages along the depression severity continuum remain unclear. Across two studies, chronic and episodic stressors were comprehensively assessed among: (a) healthy youth with (High-Risk [HR]) and without (Low-Risk [LR]) a maternal history of MDD and (b) adolescents with current MDD and suicide ideation and healthy controls (HC).

METHOD

Study 1 included LR (n = 65) and HR (n = 22) 12- to 14-year-olds (49 females; 56.32%) with no lifetime history of mental disorders. Study 2 enrolled 87 mid-to-late adolescents (64 females; 73.56%), including 57 MDD youth from a short-term intensive treatment service and 30 HCs from the community. All depressed youth reported recent suicide ideation; some had no lifetime history suicide attempts (SI; n = 31) and others reported at least one past year attempt (SA; n = 26). The Life Events and Difficulties Schedule was used to capture stressor severity in both studies.

RESULTS

We used multiple linear regression models that adjusted for demographic and clinical covariates. Being in the HR versus LR group was associated with more severe chronic (β = .22, CI95  = 0.01-0.42, p = .041), independent (β = .34, CI95  = 0.12-0.56, p = .003), and interpersonal (β = .23, CI95  = 0.004-0.45, p = .047) stress severity. By contrast, the MDD group reported significantly more severe chronic (β = .62, CI95  = 0.45-0.79, p < .001) and dependent (β = .41, CI95  = 0.21-0.61, p < .001) stress than the HC group, but not independent (p = .083) stress. Stress severity did not differ between recent attempters versus youth who reported suicide ideation alone (SA vs. SI contrast). However, the SA group reported a higher rate of targeted rejection events (RR = 3.53, CI95  = 1.17-10.70, p = .026).

CONCLUSIONS

Our findings clarify the stressor features that may most strongly contribute to adolescent depression and its clinical correlates at two important points along depression's clinical course.

Suicidal Thoughts and Behaviors Among Adolescent Psychiatric Inpatients

BACKGROUND

Given low base rates of suicidal thoughts and behaviors (STBs) in national samples of adolescents, clarifying the sociodemographic and clinical correlates among psychiatric inpatients may afford insights into potential risk factors that predict STBs onset.

METHOD

Adolescents (N = 970; ages 12-19 years) admitted for acute, psychiatric inpatient care completed baseline clinical interviews and self-report measures assessing demographics and early life adversity. Lifetime and 12-month STBs prevalence were obtained, allowing for the estimate of STBs persistence (i.e., rates of those with both current and past STBs) and transition rates (i.e., proportion of ideators that transition to plans or attempts). Univariate and multivariate logistic regression tested sociodemographic and clinical correlates of STBs.

RESULTS

Age-of-onset for STBs occurred in early adolescence. Most patients reported suicide ideation with nearly half of patients making a plan and one-third a suicide attempt. Although relatively modest, the strongest correlates of lifetime attempts were depressive disorders, physical abuse, and non-suicidal self-injury. Knowing a peer that had attempted suicide also increased the likelihood of a suicide attempt, especially among attempters who transitioned from ideation to planned attempts.

CONCLUSION

STBs are highly prevalent among adolescents admitted for acute psychiatric inpatient treatment. The modest effects suggest that correlates, particularly those related to suicide attempts, are widely distributed. As a history of physical abuse and knowing a peer with a suicide attempt history are related to transitioning from ideation to action, these may be critical factors to target in the deployment of future suicide prevention and treatment programs. HIGHLIGHTSOne-third of adolescent inpatients report a lifetime history of suicide attempts.Approximately 65% of adolescent inpatients with a lifetime plan attempt suicide.Knowing peers who attempt suicide may facilitate the transition from ideation to action.

An evaluation of the construct validity of the Adult Rejection Sensitivity Questionnaire

Rejection sensitivity (RS), the predisposition to defensively expect, readily perceive, and react strongly to interpersonal rejection (Downey & Feldman, 1996; Feldman & Downey, 1994), may be a transdiagnostic trait associated with a range of psychiatric symptoms and psychosocial dysfunction. Valid and reliable assessment of vulnerability factors is essential for individualized treatment and improving clinical outcomes. Limited research has examined the factor structure of the predominantly used self-report measure of RS, the Adult Rejection Sensitivity Questionnaire (A-RSQ; Berenson et al., 2009). Across two studies (Study 1: N = 346, 57.2% female, 76.6% White; 16.8% Hispanic/Latinx; Study 2: N = 540; 43.7% female, 80.2% White; 16.7% Hispanic/Latinx), we examined the factor structure of the A-RSQ in samples of adult U.S. residents and investigated associations with mental health correlates, including neuroticism, social anxiety, anxiety, depression, anhedonia, somatic arousal, and psychological distress. Study 2 also evaluated relations with interpersonal correlates, including introversion, submissiveness, and anxious and avoidant attachment. A two-factor solution with rejection expectancy and rejection concern representing separate factors consistently fit the data best. Distinct patterns of associations emerged suggesting that concern was more strongly associated with indicators of negative affect while expectancy was uniquely associated with diminished positive affect. Both concern and expectancy were associated with indicators of interpersonal dysfunction. Findings suggest that the current operationalization, and perhaps conceptualization, of RS as measured by the A-RSQ requires revision. Additionally, RS may be a clinically relevant transdiagnostic phenotype that influences symptom manifestation and psychosocial functioning. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

I've seen enough! Prolonged and repeated exposure to disgusting stimuli increases oculomotor avoidance

Disgust motivates avoidance of stimuli associated with pathogens. Although disgust primarily inhibits oral and epidermal contact, it may also inhibit perceptual contact, particularly given the outsize role of sensory qualities in eliciting disgust. To examine perceptual avoidance of disgust, we presented images of bodily products or spoiled food paired with neutral images for 12-s trials and recorded eye movements (Experiment 1; N = 127). We found that, overall, these disgusting images were not visually avoided compared to neutral images. However, viewing of disgusting images decreased with prolonged (within-trial) and repeated (between-trial) exposure, and these trends were predicted by self-reported disgust to the images. In Experiment 2 (N = 84), we replicated Experiment 1 with a novel set of disgusting images, as well as other unpleasant image categories (suicide, threat) and pleasant images. We found that disgusting stimuli were viewed less than the other unpleasant image categories, and we again found that viewing of disgusting images decreased with prolonged and repeated exposure. Further, we replicated the finding that disgust ratings predicted decreasing viewing of disgusting images, but only for prolonged exposure (within-trial). Unexpectedly, we found that disgust ratings predicted a similar pattern of decreasing viewing for the suicide and threat images as well. These findings suggest that disgust inhibits perceptual contact, but in competition with motivational processes that steer attention toward pathogen threats. We discuss the implications for measuring disgust with eye tracking. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Specific early maladaptive schemas differentially mediate the relations of emotional and sexual maltreatment to recent life events in youth with depression

The current study provided a novel investigation of relations among particular types of childhood maltreatment (emotional vs. physical vs. sexual maltreatment), specific cognitive schema themes and the generation of dependent versus independent life events. Participants included 227 adolescents and emerging adults (74% female; aged 12-29) in a current episode of a unipolar depressive disorder drawn from three archival cross-sectional studies. Childhood maltreatment and life events from the past 6 months were assessed using detailed contextual interviews with independent, standardized ratings. Emotional maltreatment was uniquely associated with schema themes of emotional deprivation and subjugation, and sexual maltreatment was uniquely associated with schema themes of abandonment, vulnerability and dependence/incompetence. Further, subjugation and abandonment cross-sectionally mediated the relations of emotional and sexual maltreatment, respectively, to greater dependent, but not independent, life events. Physical maltreatment was not associated with cognitive schemas or recent life events after accounting for its overlap with emotional and sexual maltreatment. Results suggest targets for cognitive intervention that may improve outcomes for youth with specific histories of emotional and sexual maltreatment.

Life Stress and Suicide in Adolescents

Stress exposure is central to theories of suicide. To advance understanding of the relation between stress and suicide, we examined whether specific, theoretically-pertinent life stressors were differentially related to suicidal thinking versus suicidal behaviors among hospitalized adolescents. Participants were 197 (144 female) adolescents aged 13 to 19 years old (M = 15.61, SD = 1.48) recruited from an acute residential psychiatric treatment program. Participants were categorized into mutually exclusive groups: psychiatric controls (n = 38) with no lifetime history of suicide ideation or suicide attempts, suicide ideators (n = 99) with current ideation and no lifetime attempts, and suicide attempters (n = 60) with a lifetime history of suicide ideation and at least one attempt in the past month. Adolescents completed the Stress and Adversity Inventory for Adolescents (Adolescent STRAIN), which assessed life events and chronic difficulties occurring in five social-psychological categories: Interpersonal Loss, Physical Danger, Humiliation, Entrapment, and Role Change/Disruption. Additionally, they completed a structured interview and symptom questionnaires to capture concurrent psychopathology. Controlling for demographic and clinical covariates, only Interpersonal Loss events distinguished attempters from psychiatric controls (OR = 2.27) and ideators (OR = 1.49); no events or difficulties differentiated ideators from controls. These effects persisted when analyses were restricted to single attempters and when events following the most recent attempt were excluded. The findings elucidate potential social-environmental triggers of suicide. Ultimately, this may improve the identification of ideators most likely to make an attempt, enabling the deployment of targeted early interventions.

Emotional Response Inhibition: A Shared Neurocognitive Deficit in Eating Disorder Symptoms and Nonsuicidal Self-Injury

Eating disorder (ED) symptoms often co-occur with non-suicidal self-injury (NSSI). This comorbidity is consistent with evidence that trait negative urgency increases risk for both of these phenomena. We previously found that impaired late-stage negative emotional response inhibition (i.e., negative emotional action termination or NEAT) might represent a neurocognitive mechanism for heightened negative urgency among people with NSSI history. The current study evaluated whether relations between negative urgency and ED symptoms similarly reflect deficits in this neurocognitive process. A total of 105 community adults completed an assessment of ED symptoms, negative urgency, and an emotional response inhibition task. Results indicated that, contrary to predictions, negative urgency and NEAT contributed independent variance to the prediction of ED symptoms, while controlling for demographic covariates and NSSI history. Worse NEAT was also uniquely associated with restrictive eating, after accounting for negative urgency. Our findings suggest that difficulty inhibiting ongoing motor responses triggered by negative emotional reactions (i.e., NEAT) may be a shared neurocognitive characteristic of ED symptoms and NSSI. However, negative urgency and NEAT dysfunction capture separate variance in the prediction of ED-related cognitions and behaviors, distinct from the pattern of results we previously observed in NSSI.

Inpatient Psychiatric Care Outcomes for Adolescents: A Test of Clinical and Psychosocial Moderators

Financial pressures have led to a reduced length of stay (LOS) in inpatient psychiatric facilities for adolescents, yet research on the outcomes of short-term programs remains scant. The present study evaluated the outcomes of an adolescent inpatient program by: (1) probing depression, anxiety, and suicidal ideation at admission and discharge and (2) testing whether clinical or psychosocial factors moderate treatment response. Participants included adolescents (n = 777) aged 13-19 years admitted to an inpatient treatment program for acute psychiatric concerns. Clinical interviews were administered to probe mental disorders and past suicidal thoughts and behaviors (STBs), and self-report measures assessed symptom severity, child abuse, and peer victimization (i.e., bullying). Results showed a significant decrease in depression, anxiety, and suicidal ideation from admission to discharge. Comorbidity, past month NSSI, and lifetime suicide attempts emerged as moderators of treatment response, and peer victimization predicted symptom severity at discharge. Although findings suggest an overall improvement, participants with more severe clinical presentations (e.g., comorbidity, past month NSSI, lifetime suicide attempts, and more severe bullying) reported greater symptom severity at admission and discharge, suggesting that these patients may benefit from longer inpatient stays to achieve further symptom reduction. Although this may incur greater costs in the short-term, it also may prevent unintended economic and psychosocial consequences in the long-term.

The Stress and Adversity Inventory for Adolescents (Adolescent STRAIN): associations with mental and physical health, risky behaviors, and psychiatric diagnoses in youth seeking treatment

BACKGROUND

Numerous theories have posited that stressors occurring over the lifespan may exert a cumulative effect on psychological and biological processes that increase individuals' risk for a variety of mental and physical health problems. Given the difficulty associated with assessing lifetime stress exposure, however, few empirical studies have directly tested these cumulative risk models of psychopathology and human health.

METHOD

To address this issue, we examined the usability, acceptability, concurrent validity, and predictive validity of the recently developed Stress and Adversity Inventory for Adolescents (Adolescent STRAIN) in 338 youth (M_age  = 15.64; 229 females) seeking mental health treatment.

RESULTS

The Adolescent STRAIN achieved high acceptability and was completed in approximately 25 min (interquartile range: 20-32 min). Concurrent associations with other measures of early adversity (Childhood Trauma Questionnaire-Short Form) and interpersonal stress (Revised Peer Experiences Questionnaire) were very good (rs = .50-.59). In analyses that adjusted for participants' age, sex, and race, the STRAIN was significantly associated with depression, anxiety, and anhedonia severity; general mental and physical health complaints; risky behavior engagement; and number of interviewer-based psychiatric diagnoses (βs = .16-.52; risk ratios = 1.006-1.014). Contrary to classic theories of stress which assume that different stressors exert similar effects on health, substantial differences were observed across the two stressor types, twelve life domains, and five core social-psychological characteristics assessed by the Adolescent STRAIN.

CONCLUSIONS

These data confirm the relevance of lifetime stress exposure for multiple health outcomes in adolescence, which can in turn inform existing theories of lifespan health. Because stress is a common presenting problem in hospitals and clinics, these data also suggest the possibility of using the Adolescent STRAIN to generate stress exposure profiles for case conceptualization and treatment planning purposes.

Investigating the psychometric properties of the Suicide Stroop Task

Behavioral measures are increasingly used to assess suicidal thoughts and behaviors. Some measures, such as the Suicide Stroop Task, have yielded mixed findings in the literature. An understudied feature of these behavioral measures has been their psychometric properties, which may affect the probability of detecting significant effects and reproducibility. In the largest investigation of its kind, we tested the internal consistency and concurrent validity of the Suicide Stroop Task in its current form, drawing from seven separate studies (N = 875 participants, 64% female, aged 12 to 81 years). Results indicated that the most common Suicide Stroop scoring approach, interference scores, yielded unacceptably low internal consistency (rs = -.09-.13) and failed to demonstrate concurrent validity. Internal consistency coefficients for mean reaction times (RTs) to each stimulus type ranged from rs = .93-.94. All scoring approaches for suicide-related interference demonstrated poor classification accuracy (AUCs = .52-.56) indicating that scores performed near chance in their ability to classify suicide attempters from nonattempters. In the case of mean RTs, we did not find evidence for concurrent validity despite our excellent reliability findings, highlighting that reliability does not guarantee a measure is clinically useful. These results are discussed in the context of the wider implications for testing and reporting psychometric properties of behavioral measures in mental health research. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Neurophysiological activity following rewards and losses among female adolescents and young adults with borderline personality disorder

Borderline personality disorder (BPD) is a complex and debilitating psychiatric illness. Prior research in adults has shown that neurophysiological deficits in feedback processing and learning from rewards may be central to the development of BPD; however, little research has examined these markers in adolescents and young adults with BPD. The present study used event-related potentials and time-frequency decomposition analysis to probe neural responses to wins and losses in a guessing task among 68 females (13 to 23 years old) either with BPD (n = 35) or no history of mental disorders (healthy control [HC]; n = 33). Participants completed a guessing task wherein they won and lost money at equal frequencies while electroencephalogram (EEG) data were acquired. Adolescents and young adults with BPD showed a smaller differentiation between wins and losses in the reward positivity (RewP) relative to HCs. Using time-frequency decomposition, we isolated distinct frequency bands sensitive to wins (delta = < 3Hz) and losses (theta = 4 Hz to 7 Hz). Compared with BPD participants, HCs showed significantly larger delta power to wins, specifically. The groups did not differ in delta power to losses, nor theta power to wins or losses. Collectively, findings implicate altered reward processing in the pathophysiology of BPD and may inform early identification and targeted intervention. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Peer Victimization and Suicidal Thoughts and Behaviors in Depressed Adolescents

Suicide is a leading cause of death among youth worldwide, and depressed adolescents are at a significantly elevated risk to report suicidal ideation, planning, and attempts. Peer victimization is a robust predictor of adolescent suicidal thoughts and behaviors (STBs), but little research has focused on why bullying leads to suicidal thoughts and behaviors. To address this empirical gap, we recruited 340 (246 female) depressed adolescents ages 13-19 (M = 15.59, SD = 1.41) within 48 h of admission for acute psychiatric treatment. At the initial assessment, participants were administered clinical interviews characterizing psychopathology, nonsuicidal self-injury, and STBs (ideation, plans, and attempts). Further, they completed questionnaires assessing 3 forms of victimization (overt, relational, and reputational), recent risky behavior engagement, and psychiatric symptom severity. Controlling for internalizing symptoms and age, overt and reputational bullying were associated with more frequent past month suicide attempts, but not suicide ideation. Past month risky behavior engagement, but not NSSI, mediated the relation between victimization and attempts. However, sex differences revealed that this effect only held for males whereas bullying was directly associated with suicide attempts among females. In contrast, overt and relational bullying were non-linearly associated with suicide plans, and these relations were not mediated by risky behaviors or NSSI. Results highlight the complex network of factors that lead victimized adolescents to engage in STBs and may inform targeted suicide prevention and intervention programs.

Maternal- versus paternal-perpetrated maltreatment and risk for sexual and peer bullying revictimization in young women with depression

BACKGROUND

Childhood maltreatment is one of the strongest predictors of sexual and peer bullying re-victimization. However, it is not clear which types of maltreatment are associated with the greatest risk.

OBJECTIVE

The current study examined the differential relations of maternal- versus paternal-perpetrated emotional maltreatment, neglect, and physical maltreatment, as well as sexual maltreatment, to sexual victimization and peer bullying victimization outside the home. It was hypothesized that paternal-perpetrated emotional maltreatment would be the strongest predictor of later sexual and peer bullying victimization, and that sexual maltreatment would predict sexual re-victimization.

PARTICIPANTS AND SETTING

Participants included data from 263 adolescent and young adult women who had previously taken part in one of three larger studies conducted in an academic research setting investigating the relation between stress and depression. All participants had been recruited from the wider community or clinician referral and met criteria for a unipolar depressive disorder.

METHODS

Psychiatric diagnoses were assessed with a structured diagnostic interview. Childhood maltreatment and victimization were assessed retrospectively with a semi-structured contextual interview that includes standardized ratings.

RESULTS

Paternal-perpetrated emotional abuse was the only maltreatment type that was independently associated with sexual (OR = 3.09, p =  .004) and peer bullying (OR = 1.41, p =  .05) re-victimization over other forms of maltreatment and indicators of depression severity.

CONCLUSIONS

These findings provide an important foundation for future research examining the mechanisms driving the relation between father's hostility, criticism, and rejection and daughters' revictimization that can ultimately provide targets for prevention in girls at highest risk.

Non-Suicidal self-injury and suicide in depressed Adolescents: Impact of peer victimization and bullying

BACKGROUND

While prior research has demonstrated that peer victimization and bully perpetration contribute to non-suicidal self-injury (NSSI) and suicidal thoughts and behaviors (STBs), it remains unclear whether these interpersonal processes differentiate self-injuring adolescent suicide ideators and attempters.

METHODS

The study included adolescents aged 13-18 years (n = 223; M = 15.31, SD = 1.34) recruited from an acute inpatient program. Participants were divided into two groups: (1) NSSI_SI (n = 106): endorsed past year NSSI, current suicide ideation, and no lifetime suicide attempts and (2) NSSI_SI+SA (n = 117): endorsed past year NSSI, current suicide ideation, and lifetime suicide attempts. Adolescents completed clinical interviews (i.e., mental disorders, NSSI, and STBs) and self-report measures assessing peer victimization, bully perpetration, and depression severity.

RESULTS

NSSI_SI+SA youth reported higher levels of peer victimization and bully perpetration than NSSI_SI youth (ps < 0.01, ds = 0.36-0.37). Among the NSSI_SI+SA youth, bully perpetration was associated with a greater number of past month suicide attempts (p = 0.02, RR = 1.07). Only peer victimization was associated with greater NSSI behaviors in the past month (p = 0.04, RR = 1.01).

LIMITATIONS

The study is cross-sectional, and reports of peer victimization and bully perpetration rely on self-report assessment.

CONCLUSIONS

Peer victimization and bully perpetration differentiated adolescent suicide ideators and attempters, highlighting the need to address bully perpetration in addition to peer victimization in suicide interventions and research.

Treatment Effects following Residential Dialectical Behavior Therapy for Adolescents with Borderline Personality Disorder

Dialectical behavior therapy (DBT) is an empirically supported treatment for borderline personality disorder (BPD) in adults, however fewer studies have examined outcomes in adolescents. This study tested the effectiveness of an intensive 1-month, residential DBT treatment for adolescent girls meeting criteria for BPD. Additionally, given well-established associations between BPD symptoms and childhood abuse, the impact of abuse on treatment outcomes was assessed. Participants were female youth (n = 53) aged 13-20 years (M = 17.00, SD = 1.89) completing a 1-month residential DBT program. At pre-treatment, participants were administered a diagnostic interview and self-report measures assessing BPD, depression, and anxiety symptom severity. Following one month of treatment, participants were re-administered the self-report instruments. Results showed significant pre- to post-treatment reductions in both BPD and depression symptom severity with large effects. However, there was no significant change in general anxious distress or anxious arousal over time. The experience of childhood abuse (sexual, physical, or both) was tested as moderator of treatment effectiveness. Although experiencing multiple types of abuse was related to symptom severity, abuse did not moderate the effects of treatment. Collectively, results indicate that a 1-month residential DBT treatment with adolescents may result in reductions in BPD and depression severity but is less effective for anxiety. Moreover, while youth reporting abuse benefitted from treatment, they were less likely to achieve a clinically significant reduction in symptoms.

A longitudinal investigation of the Concise Health Risk Tracking Self-Report (CHRT-SR) in suicidal patients during and after hospitalization

The Concise Health Risk Tracking Self-Report (CHRT-SR) scale is a brief self-report instrument to assess suicide risk. Initial investigations have indicated good psychometric properties in psychiatric outpatients. The aims of this paper were to examine the construct validity and factor structure of the twelve- (CHRT-SR12) and seven-item (CHRT-SR7) versions and to test if clinically expected within-person changes in suicide risk over time were measurable using the CHRT-SR in two study cohorts hospitalized for suicidal ideation or behavior: (1) patients with major depressive disorder (MDD) who participated in a psychological intervention trial, n = 65, and (2) participants with bipolar disorder or MDD in an observational study, n = 44. The CHRT-SR12 and self-report measures of hopelessness, depression, and positive psychological states were administered during admission and several times post-discharge. Both versions showed good internal consistency in inpatients and confirmed the three-factor structure (i.e., hopelessness, perceived lack of social support and active suicidal ideation and plans) found in outpatients. CHRT-SR scores had strong correlations with negative and positive affective constructs in the expected directions, and indicated decreases in suicide risk following discharge, in line with clinical expectations. The CHRT-SR12 and CHRT-SR7 are promising self-report measures for assessing suicide risk in very high-risk patient populations.

Emotion processing in female youth: Testing the stability of the late positive potential

The Emotional Interrupt Task (EIT) has been used to probe emotion processing in healthy and clinical samples; however, research exploring the stability and reliability of behavioral measures and ERPs elicited from this task is limited. Establishing the psychometric properties of the EIT is critical, particularly as phenotypes and biological indicators may represent traitlike characteristics that underlie psychiatric illness. To address this gap, test-retest stability and internal consistency of behavioral indices and ERPs resulting from the EIT in healthy, female youth (n = 28) were examined. At baseline, participants were administered the EIT while high-density 128-channel EEG data were recorded to probe the late positive potential (LPP). One month later, participants were readministered the EIT. Four principal findings emerged. First, there is evidence of an interference effect at baseline, as participants showed a slower reaction time for unpleasant and pleasant images relative to neutral images, and test-retest of behavioral measures was relatively stable over time. Second, participants showed a potentiated LPP to unpleasant and pleasant images compared to neutral images, and these effects were stable over time. Moreover, in a test of the difference waves (unpleasant-neutral vs. pleasant-neutral), there was sustained positivity for unpleasant images. Third, behavioral measures and LPP demonstrated excellent internal consistency (odd/even correlations) across conditions. Fourth, highlighting important age-related differences in LPP activity, younger age was associated with larger LPP amplitudes across conditions. Overall, these findings suggest that the LPP following emotional images is a stable and reliable marker of emotion processing in healthy youth.

Cognitive Control Deficits Differentiate Adolescent Suicide Ideators From Attempters

OBJECTIVE

Mental illness and suicidal ideation are among the strongest correlates of suicidal behaviors, but few adolescents with these risk factors make a suicide attempt. Therefore, it is critical to identify factors associated with the transition from suicide ideation to attempts. The present study tested whether deficits in cognitive control in the context of suicide-relevant stimuli (ie, suicide interference) reliably differentiated adolescent ideators and attempters.

METHODS

Adolescents (n = 99; 71 girls) aged 13-18 years (mean = 15.53, SD = 1.34) with recent suicide ideation (n = 60) or a recent suicide attempt (n = 39) were recruited from an acute residential treatment facility between August 2012 and December 2013. We measured interference to suicide-related, negative, and positive words using the Suicide Stroop Task (SST).

RESULTS

When stimuli were analyzed separately, suicide attempters showed greater interference for suicide (t₉₇ = 2.04, P = .044, d = 0.41) and positive (t₉₇ = 2.63, P = .010, d = 0.53) stimuli compared to suicide ideators. An additional omnibus interference (suicide, negative, positive) x group (suicide ideator, suicide attempter) analysis of variance revealed a main effect of group (F₁,₉₇ = 4.31, P = .041, ηp² = 0.04) but no interaction (P = .166), indicating that attempters showed greater interference for emotional stimuli, regardless of valence. Multiple attempters drove this effect; single attempters and ideators did not differ in SST performance (P = .608).

CONCLUSIONS

General deficits in cognitive control in the context of emotional stimuli may be a marker of adolescent suicide risk.

Predictors of Rehospitalization for Depressed Adolescents Admitted to Acute Psychiatric Treatment

OBJECTIVE

Presently, little is known about what factors predict adolescent psychiatric rehospitalization. Thus, the present study tested whether a battery of demographic and clinical characteristics predicted readmission within 6 months of discharge.

METHODS

Participants were 165 adolescents (112 females) aged 13-19 years (mean = 15.61, SD = 1.48) admitted to an acute residential treatment program between November 25, 2013, and November 18, 2014. Patients met diagnostic criteria (DSM-IV-TR) for current major depressive disorder or dysthymia. At admission, participants completed a battery of clinical interviews and questionnaires assessing demographics, early life stress, comorbid diagnoses, psychiatric symptoms, suicidality, self-injury, and risky behavior engagement. At discharge, psychiatric symptoms were reassessed. Readmission to the same residential service was monitored over a 6-month period following discharge.

RESULTS

Overall, 12.1% of adolescents were rehospitalized. We conducted a series of Cox regression survival analyses to test demographic and clinical predictors of patients' time to readmission. More frequent self-injurious behaviors in the month prior to hospitalization was significantly associated with a more rapid time to rehospitalization (β = 0.05, SE = .02, Wald₁ = 4.35, P = .037, OR = 1.05, 95% CI = 1.003-1.10).

CONCLUSIONS

It is critical to more effectively manage self-injury during the treatment of depressed adolescents, as this is the strongest predictor of later rehospitalization.

Adolescent self-injurers: Comparing non-ideators, suicide ideators, and suicide attempters

Adolescent non-suicidal self-injury (NSSI) and suicidality are serious health concerns; however, factors that contribute to the transition from NSSI to suicide ideation and suicide attempts are unclear. To address this gap, we investigated whether demographic characteristics, child maltreatment, and psychiatric factors are associated with the level suicidality among adolescents with a history of self-injury. Participants were three groups of adolescent inpatient self-injurers (n = 397, 317 female), aged 13-18 years (M = 15.44, SD = 1.36): (a) non-ideators (n = 96; no current suicide ideation and no lifetime suicide attempts), (b) suicide ideators (n = 149; current ideation and no lifetime attempts), and (c) suicide attempters (n = 152; current ideation and at least one lifetime attempt). Participants completed interviews assessing psychiatric diagnoses, suicidality, and NSSI characteristics, as well as questionnaires on childhood trauma, psychiatric symptoms, and risky behavior engagement. Depression severity was associated with greater odds being a suicide ideator (p < 0.001, OR = 1.04) and an attempter (p < 0.001, OR = 1.05) compared to a non-ideator. Suicide attempters used more NSSI methods and reported greater risky behavior engagement than non-ideators (p = 0.03, OR = 1.29 and p = 0.03, OR = 1.06, respectively) and ideators (p = 0.015, OR = 1.25 and p = 0.04, OR = 1.05, respectively); attempters used more severe NSSI methods (e.g., burning). Our results identify a wide range of risk markers for increasing lethality in a sample at high risk for suicide mortality; future research is needed to refine risk assessments for adolescent self-injurers and determine the clinical utility of using risk markers for screening and intervention.

Testing a Revised Interpersonal Theory of Depression Using a Laboratory Measure of Excessive Reassurance Seeking

OBJECTIVE

This study tested whether core beliefs with themes of abandonment and rejection moderated the link between trait and behavioral excessive reassurance seeking (ERS) and interpersonal rejection.

METHOD

Participants were 118 women with high (n = 43; mean [M]_age = 18.58, standard deviation [SD]_age = 1.24) and low (n = 75; M_age = 18.58, SD_age = 1.24) levels of depression symptoms and their male romantic partners. Couples reported their depression, ERS, abandonment/rejection cognitions, and relationship quality. We also coded women's reassurance-seeking behavior during an audiotaped discussion task.

RESULTS

Among women with high levels of depression symptoms and low levels of abandonment/rejection core beliefs, behavioral ERS was associated with lower partner-reported relationship quality. Self-reported ERS was significantly associated with partner relationship quality, but the effect was not moderated by depression or core beliefs.

CONCLUSIONS

ERS is a potent predictor of stress and subsequent depression. Our findings underscore the need to better understand factors (e.g., cognitions, partner characteristics) that may determine whether ERS behaviors beget interpersonal stress and rejection.

Electrocortical Reactivity During Self-referential Processing in Female Youth With Borderline Personality Disorder

BACKGROUND

Borderline personality disorder (BPD) is debilitating, and theoretical models have postulated that cognitive-affective biases contribute to the onset and maintenance of BPD symptoms. Despite advances, our understanding of BPD pathophysiology in youth is limited. The present study used event-related potentials (ERPs) to identify cognitive-affective processes that underlie negative self-referential processing in BPD youth.

METHODS

Healthy females (n = 33) and females with BPD (n = 26) 13 to 22 years of age completed a self-referential encoding task while 128-channel electroencephalography data were recorded to examine early (i.e., P1 and P2) and late (late positive potential [LPP]) ERP components. Whole-brain standardized low-resolution electromagnetic tomography explored intracortical sources underlying significant scalp ERP effects.

RESULTS

Compared to healthy females, participants with BPD endorsed, recalled, and recognized fewer positive and more negative words. Moreover, unlike the healthy group, females with BPD had faster reaction times to endorse negative versus positive words. In the scalp ERP analyses, the BPD group had greater P2 and late LPP positivity to negative as opposed to positive words. For P2 and late LPP, whole-brain standardized low-resolution electromagnetic tomography analyses suggested that females with BPD overrecruit frontolimbic circuitry in response to negative stimuli.

CONCLUSIONS

Collectively, these findings show that females with BPD process negative self-relevant information differently than healthy females. Clinical implications and future directions are discussed.

Predicting suicide attempts in depressed adolescents: Clarifying the role of disinhibition and childhood sexual abuse

BACKGROUND

Suicide is the second leading cause of death among adolescents, and depressed youth are six times more likely to make suicide attempts as compared to non-depressed adolescents. The present study examined the unique and interactive effects of two well-established correlates of suicidality - childhood sexual abuse (CSA) and disinhibition - in predicting suicide attempts among depressed adolescents.

METHOD

Participants were 163 adolescents (125 females) aged 13-18 (M=15.60, SD=1.27) diagnosed with Major Depressive Disorder (n=95, 58.3%) and/or Dysthymia (n=69, 42.3%) recruited from an acute residential treatment service. Participants completed interviews assessing psychopathology and suicidality, self-report measures of depressive symptoms and CSA, and a computerized disinhibition task.

RESULTS

Consistent with hypotheses, CSA moderated the association between disinhibition and adolescents' report of their past year and lifetime suicide attempts. Specifically, higher disinhibition was associated with a greater likelihood of having made a suicide attempt among adolescents with a history of CSA, but not among those without. The same pattern of results held in analyses of suicide attempt frequency.

LIMITATIONS

Primary findings were based on observational, cross-sectional data, and therefore, causal relationships cannot be inferred. The gender imbalance in the sample precluded stratifying our analyses by gender. CSA was ascertained by self-report; replication of the results with more objective measures is warranted.

CONCLUSIONS

Our findings indicate that CSA and disinhibition may work together to predict elevated suicide risk, and these results have implications for early identification efforts in youth at high risk for suicide.

Identifying differences between depressed adolescent suicide ideators and attempters

BACKGROUND

Adolescent depression and suicide are pressing public health concerns, and identifying key differences among suicide ideators and attempters is critical. The goal of the current study is to test whether depressed adolescent suicide attempters report greater anhedonia severity and exhibit aberrant effort-cost computations in the face of uncertainty.

METHODS

Depressed adolescents (n=101) ages 13-19 years were administered structured clinical interviews to assess current mental health disorders and a history of suicidality (suicide ideators=55, suicide attempters=46). Then, participants completed self-report instruments assessing symptoms of suicidal ideation, depression, anhedonia, and anxiety as well as a computerized effort-cost computation task.

RESULTS

Compared with depressed adolescent suicide ideators, attempters report greater anhedonia severity, even after concurrently controlling for symptoms of suicidal ideation, depression, and anxiety. Additionally, when completing the effort-cost computation task, suicide attempters are less likely to pursue the difficult, high value option when outcomes are uncertain. Follow-up, trial-level analyses of effort-cost computations suggest that receipt of reward does not influence future decision-making among suicide attempters, however, suicide ideators exhibit a win-stay approach when receiving rewards on previous trials.

LIMITATIONS

Findings should be considered in light of limitations including a modest sample size, which limits generalizability, and the cross-sectional design.

CONCLUSIONS

Depressed adolescent suicide attempters are characterized by greater anhedonia severity, which may impair the ability to integrate previous rewarding experiences to inform future decisions. Taken together, this may generate a feeling of powerlessness that contributes to increased suicidality and a needless loss of life.

EMOTION-PROCESSING BIASES AND RESTING EEG ACTIVITY IN DEPRESSED ADOLESCENTS

BACKGROUND

Although theorists have posited that adolescent depression is characterized by emotion-processing biases (greater propensity to identify sad than happy facial expressions), findings have been mixed. Additionally, the neural correlates associated with putative emotion-processing biases remain largely unknown. Our aim was to identify emotion-processing biases in depressed adolescents and examine neural abnormalities related to these biases using high-density resting EEG and source localization.

METHODS

Healthy (n = 36) and depressed (n = 23) female adolescents, aged 13-18 years, completed a facial recognition task in which they identified happy, sad, fear, and angry expressions across intensities from 10% (low) to 100% (high). Additionally, 128-channel resting (i.e., task-free) EEG was recorded and analyzed using a distributed source localization technique (low-resolution electromagnetic tomography (LORETA)). Given research implicating the dorsolateral prefrontal cortex (DLPFC) in depression and emotion processing, analyses focused on this region.

RESULTS

Relative to healthy youth, depressed adolescents were more accurate for sad and less accurate for happy, particularly low-intensity happy faces. No differences emerged for fearful or angry facial expressions. Further, LORETA analyses revealed greater theta and alpha current density (i.e., reduced brain activity) in depressed versus healthy adolescents, particularly in the left DLPFC (BA9/BA46). Theta and alpha current density were positively correlated, and greater current density predicted reduced accuracy for happy faces.

CONCLUSION

Depressed female adolescents were characterized by emotion-processing biases in favor of sad emotions and reduced recognition of happiness, especially when cues of happiness were subtle. Blunted recognition of happy was associated with left DLPFC resting hypoactivity.

Acute and chronic stress exposure predicts 1-year recurrence in adult outpatients with residual depression symptoms following response to treatment

BACKGROUND

One of the strongest predictors of depression recurrence in those who respond to treatment is the presence of residual depressive symptoms. Our goal was to examine stressful life event exposure as a mechanism of recurrence in previously depressed patients with residual depression symptoms. That is, we predicted that higher levels of residual symptoms will significantly predict exposure to acute life events that will then heighten prospective recurrence risk.

METHODS

Participants included 68 adult outpatients with major depression (42 women; age 18-60) who completed a 12-month naturalistic follow-up after achieving remission in a 20-week randomized, open label trial of interpersonal psychotherapy, cognitive-behavioral therapy, or antidepressant medication. Depression recurrence was defined as the reemergence of an episode of major depression as determined by structured interview. Acute life events and chronic stressors were assessed at the end of follow-up using a contextual interview.

RESULTS

Posttreatment depression scores significantly prospectively predicted an increased risk for recurrence, and acute life events in the follow-up period. Cox regression survival analyses modeling life events as time-dependent covariates showed that life event exposure mediated the relation of residual symptoms to recurrence even controlling for chronic stress.

CONCLUSIONS

Our findings implicate residual symptoms in heightening depression recurrence risk through exposure to stressful life events. Depression recurrence adds significantly to the burden of the disorder. Therefore, rigorous follow-up of patients targeting the stressful context has the potential to prevent a lifelong pattern of illness.

Symptom specificity in the acute treatment of Major Depressive Disorder: a re-analysis of the treatment of depression collaborative research program

BACKGROUND

Antidepressant medications, Cognitive-Behavioral Therapy (CBT) and Interpersonal Psychotherapy (IPT) are equally efficacious in the acute treatment of Major Depressive Disorder (MDD). Nevertheless, remission rates remain unacceptably low. Examining the differential time course of remission of specific symptom clusters across treatments may provide a basis for assigning patients to treatments that have the highest chance of being effective.

METHODS

This study re-analyzed data from the NIMH Treatment of Depression Collaborative Research Project (TDCRP), which included 250 adult outpatients with MDD randomized to 16 weeks of CBT, IPT, imipramine+clinical management (IMI-CM), or pill placebo (PLA-CM). We derived four symptom factors from the 23-item Hamilton Depression Rating Scale, and three symptom factors from the Beck Depression Inventory. Within-subject hierarchical regression models were specified to examine the linear and quadratic patterns of symptom remission over five assessment points.

RESULTS

IMI-CM produced a more rapid rate of remission than CBT or IPT for both the somatic/vegetative and cognitive-affective symptoms of MDD. There were no statistically significant differences in the rates of improvement of any of the symptom factors between the IMI-CM and PLA-CM groups.

LIMITATIONS

Some core symptoms of depression were excluded due to low factor loadings. Past research has argued that the CBT arm in the TDCRP may have been weak.

CONCLUSIONS

We failed to find evidence that treatments act preferentially on specific symptom clusters. Therefore, the symptoms of MDD may be inter-dependent when it comes to their courses of remission in treatment.

Cortisol reactivity to social stress in adolescents: role of depression severity and child maltreatment

This study examined the hypothesis that depressed adolescents with a history of childhood maltreatment will show greater cortisol reactivity to psychological stress challenge than those without, and this relation will be moderated by level of depression severity. Seventy-one adolescents were exposed to the Trier Social Stress Test. Salivary cortisol was assessed at baseline, immediately before the challenge, after the challenge, and during an extended recovery period. Childhood maltreatment was assessed with a rigorous contextual interview and rating system. Adolescents with a history of maltreatment produced higher and more prolonged levels of cortisol in response to the challenge than did adolescents with no maltreatment, but only among those with a mild/moderate level of depression severity. Those with moderate/severe depression exhibited a blunted cortisol response regardless of child maltreatment history. These findings indicate that depression is a heterogeneous syndrome, and that both depression severity and child maltreatment history should be considered in studies examining biological stress reactivity.

Symptom specificity and the prospective generation of life events in adolescence

The purpose of the present study was to uncover patterns in the generation of life events from symptom profiles and specific depression symptoms in an effort to obtain a fine-grained understanding of the stress-generation phenomenon. A community sample of 161 adolescents completed the Beck Depression Inventory-II (A. T. Beck, 1996) at Time 1, and then 88 returned 1 year later for an assessment of life events using a rigorous contextual interview and rating system. Consistent with hypotheses, and controlling for baseline stress, cognitive-affective symptoms of depression prospectively predicted higher levels of dependent interpersonal life events. In contrast, somatic symptoms prospectively predicted higher levels of independent life events. Further examination of the types of events generated by specific symptoms suggests that different mechanisms may drive specific patterns of symptom-event generation and suggests that broadening the definition of independence may be necessary to capture the full context of event generation.

Primary and revision total hip replacement in patients who are Jehovah's Witnesses

The Jehovah's Witnesses do not accept allogeneic blood transfusion or certain types of autologous blood transfusion and, therefore, present the orthopaedic surgeon with a challenge in the management of perioperative blood loss. Accepting a patient who is a Jehovah's Witness as a surgical candidate requires the surgeon to be prepared medically to use known techniques to limit red blood cell loss or increase red blood cell mass, to resort to extraordinary means when necessary, and to be prepared philosophically to deal with catastrophic blood loss in a patient who may refuse even potentially life-saving transfusion. Issues pertinent to the management of intraoperative blood loss in the patient who is a Jehovah's Witness require careful delineation and specific treatment guidelines. The authors herein review their past and current experiences in the perioperative blood management of this patient population in an attempt to address this need.

Human performance evaluation of a metaphor graphic display for respiratory data

Metaphor graphics are data displays designed to look like corresponding variables in the real world, but in a non-literal sense of "look like". Evaluation of the impact of these graphics on human problem solving has twice been carried out, but with conflicting results. The present experiment attempted to clarify the discrepancies between these findings by using a complex task in which expert subjects interpreted respiratory data. The metaphor graphic display led to interpretations twice as fast as a tabular (flowsheet) format, suggesting that conflict between earlier studies is due either to differences in training or to differences in goodness of metaphor. Findings to date indicate that metaphor graphics work with complex as well as simple data sets, pattern detection as well as single number reporting tasks, and with expert as well as novice subjects.

Metaphor graphics to support integrated decision making with respiratory data

Support for data integration in the intensive care unit (ICU) often includes efforts to improve the display of data. An electronic version of a flowsheet (table of numbers) with optimal line graphs is by far the most common format in current ICU computer workstation technology, yet there is little evidence that this format provides particularly good support for human integration of data. The present work introduces a new form of graphic representation, one that is far more metaphoric, far more tailored to the intensive care unit than a line graph. This graphic system, called volume rectangles represents mechanical ventilator data in such a way that is easy to keep different types of variables conceptually separated, yet easy to see how they relate in a truly integrated way. Volume rectangles are one example of a general approach to display of data called the metaphor graphic approach, which is being evaluated in this and other contexts. Metaphor graphics are custom tailored visual displays designed to look like the real world situation from which the data is collected but not in a literal sense of 'look like'. Anecdotal observation suggests that such graphics are easy to learn, are remembered over long period, and are good decision support tools when the task is finding patterns in a mass of data.

Formulas for calculation of extraction volumes for commonly used pesticide residue extraction procedures

Formulas are presented for the calculation of extraction volume for pesticide residue procedures that use a single extraction with acetone, acetonitrile, or methanol, with or without prior dilution of these solvents with water. These formulas account for the volume change on mixing and for the volume contribution from the soluble sugars sucrose, glucose, and fructose. Results using these formulas are in agreement with the observed volumes of such mixtures within 0.3% throughout the following ranges, expressed as percent water in the mixtures: 15-38% for acetone, 4.8-59% for acetonitrile, and 9.3-33% for methanol.

Gastrointestinal blood loss and anemia in runners

Iron deficiency, with or without anemia, occurs commonly in long-distance runners, but the cause is unknown. The recent development of a simple quantitative assay for fecal hemoglobin, HemoQuant , allowed us to study whether gastrointestinal bleeding occurs in runners. Blood and stool samples were collected from 24 runners before and after a race of 10 to 42.2 km and from age- and sex-matched, nonrunning controls. The mean blood hemoglobin level and hematocrit were significantly lower in runners than in controls. Serum ferritin levels were below normal in 4 runners but in no controls. Fecal hemoglobin levels increased in 20 of 24 runners (p less than 0.01) after a race. Mean fecal hemoglobin level was 1.08 mg/g (range, 0.11 to 2.36) in controls and 0.99 mg/g (0.18 to 2.41) in runners before a race, but peaked at 3.96 mg/g (0.37 to 43.20) after a race. Competitive long-distance running induces gastrointestinal blood loss and may contribute to iron deficiency.

The tolerance of re-irradiation of heavily irradiated human skin

The clinical course of a group of 15 female patients treated with X-ray therapy for radiation-induced hypopharyngeal tumours is reviewed. Neither acute nor late skin reactions exceeded those expected in similar radical treatments of patients not previously irradiated. One patient appeared to have been cured by the treatment and four achieved two years' palliation. It is suggested that the tolerance of skin to re-irradiation following a long period may approach normal.

Re-irradiation of rat tails to necrosis at six months after treatment with a "tolerance" dose of x rays or neutrons

Rat tails were re-irradiated to necrosis levels at about six months after various fractionated treatments with 290 kV X rays or 14 MeV neutrons. The X ray dose required to produce necrosis in half of a group of tails (ND50), which had been heavily X-irradiated six months before, was 91+/-4% of the ND50 for aged controls. After prior neutron-irradiation, however, this value was 87+/-4% (neutrons in second treatment) or 75+/-5% (X rays in second course). The "effective" oxygenation of mouse tails at this time after X-irradiation was similar to that of controls; thus these percentage dose values indicate the remarkable tolerance of this organized tissue to a second course of X-irradiation, and the presence of more residual injury in neutron-irradiated tissues.

Evidence for conformeric states of rhodopsin

Spectrophotometric measurements of metarhodopsin II appearance are made on five different kinds of rhodopsin preparations. Although the preparations differ greatly in their rhodopsin: phospholipid ratio, the meta II kinetics in all of them are strikingly similar in certain respects. Meta II appearance kinetics in all of the preparations are best described by two and only two exponentials. The ratio of these two rates is always about 5. The fast fraction: slow fraction ratio depends upon temperature. These fractions are reversibly convertible in the dark, and are interconverted on a time-scale which is long compared to the meta II appearance rate. It is shown that the kinetics of the earlier step in the bleaching sequence, viz., lumi-leads to meta I, is also described by double exponentials. Again the ratio of rates is ca. 5 and the fast-slow fractions correspond to those found in the meta I leads to meta II step. It is proposed that these facts support an hypothesis for the existence of two conformeric states of rhodopsin which are in thermal equilibrium. Thermodynamic parameters associated with this proposed equilibrium are presented.

Tolerance of rodent tails to necrosis after "daily" fractionated X rays or D-T neutrons

The rat tail has been used as a model system to study the necrosis of an organized tissue following fractionated doses of collimated D-T neutrons or 290 kV X rays. RBE values for tail tolerance - 10 per cent of tails necrosing after the early skin reactions - rise from about 1-7 (single doses) to about 3-1 (16 fractions in 22 days). Neutron tolerance doses are almost independent of fractionation from 2 to 16 fractions. The tissues at risk are shown to be rather hypoxic. Early skin reaction levels can be used to predict the fraction of tails that will necrose. Early peak reactions for a given fraction of necrotic tails were slightly higher for neutrons than for X rays, and this difference was consistent for all the dose fractionation schedules employed.