The problem with confidence: too much and too little results in poorer achievement, inner conflict, and social inhibition

Introduction

Confidence is defined as the feelings and thoughts people have during a task that result in judgments about their performance. Evidence suggests that confidence is trait-like, but thus far research on the relative match between confidence and accuracy has been primarily restricted to over-confidence effects, and subject to the methodological flaws involved with using difference scores. We sought to answer an exploratory question in this research, whether discrepancies in ability and confidence in either direction reliably predicted individual differences on a broad-spectrum and commercially available personality test, the California Psychological Inventory (CPI260).

Methods

Participants were 220 employed adults who had previously taken the CPI260 for career development purposes. They were invited to complete a measure of cognitive ability and confidence in return for feedback on the same. Data were modeled using polynomial regression and response surface analysis, to determine whether and how CPI260 personality traits were associated with matches or mismatches between accuracy and confidence in the same test.

Results

We identified negative curvilinear effects along the line of disagreement for four CPI260 scales, suggesting that both under- and over-confidence were associated with personality.

Discussion

In contrast to our expectations, individuals who were under-confident and those who were over-confident had lower achievement potential, less social confidence, and more inner conflict than other individuals in this sample. Although preliminary, these findings suggest that both over-confident and under-confident individuals are aware of potential weaknesses that impede their functioning.

Examination of bidirectional relationships between fear of negative evaluation and weight/shape concerns over 3 years: A longitudinal cohort study of Australian adolescents

OBJECTIVE

Adolescents commonly experience both fear of negative evaluation and weight/shape concerns. However, evidence concerning the prospective associations between these constructs during adolescence is limited. The current study examined the bidirectional relationships between fear of negative evaluation and weight/shape concerns over a 3-year period in adolescents.

METHOD

Australian high school students (n = 2073; 55% girls) completed self-report measures at three timepoints, each 1 year apart.

RESULTS

Findings showed a bidirectional relationship, whereby increases in fear of negative evaluation predicted exacerbated weight/shape concerns, and vice versa. Results point towards a vicious maintenance cycle between fear of negative evaluation and weight/shape concerns.

DISCUSSION

Findings from the current study highlight the importance of considering both fear of negative evaluation and weight/shape concerns in the development of health promotion and prevention programs designed to reduce the occurrence and adverse effects of body dissatisfaction or improve general mental health.

PUBLIC SIGNIFICANCE

Many adolescents experience some level of fear of negative evaluation (i.e., worry about being judged by others) and worry about their weight and/or shape. This study examined the prospective relationship between both constructs. Findings showed a bidirectional relationship, whereby higher fear of negative evaluation predicted increased weight/shape concerns, and vice versa. Programs designed to reduce body dissatisfaction might be improved by targeting both fear of negative evaluation and weight/shape concerns.

"Life's too short to be small": An experimental exploration of the relationship between death anxiety and muscle dysmorphia symptoms

Growing research demonstrates that death anxiety is strongly associated with numerous mental health conditions. It is possible that death anxiety may similarly contribute to behaviours associated with muscle dysmorphia (MD). The current pre-registered study examined this possibility in 322 young men with an interest in health and fitness. The mortality salience paradigm was used to experimentally examine whether reminders of death increased behaviours relevant to MD. Measures of MD symptoms and death anxiety were also completed by participants. Contrary to expectations, reminders of death did not significantly increase willingness to trial workout supplements, or dissatisfaction with current muscularity. Participants reminded of death reported lower intention to exercise in the near future, compared to the control condition. Moreover, death reminders did not lead to significantly larger portion sizes being chosen. However, in post-hoc analyses, men with high, but not low, MD symptoms did choose larger portions after being primed with death. Lastly, positive correlations were found between self-report measures of MD symptoms and two measures of death anxiety. Cumulatively, these results suggest that while fears of death may be associated with self-reported MD symptoms, they may not drive excessive exercise, nor body dissatisfaction in men.

Anabolic-Androgenic Steroid Use: Patterns of Use among a National Sample of Canadian Adolescents and Young Adults

Background

Androgenic-anabolic steroid (AAS) use is relatively common among international recreational and community samples and is associated with several deleterious side effects and health consequences that have not been studied recently among a large Canadian sample. Therefore, the purpose of this study was to assess and describe characteristics of AAS users compared to non-AAS users among a national sample of Canadian adolescents and young adults.

Methods

Data from 2,774 adolescents and young adults from the Canadian Study of Adolescent Health Behaviors were analyzed. Participants were recruited via social media advertisements and completed the survey online. Survey items measured sociodemographics, AAS use, AAS side effects, motives for AAS use, AAS administration, body satisfaction, other illicit substance use, mental health, and violence involvement.

Results

Among the overall sample, 1.6% of participants reported lifetime AAS use, with the majority of users being White, heterosexual males. Most users strived to gain weight, with main motives for AAS use including increased muscularity and strength, and improved appearance. Most AAS users were satisfied with their body compared to non-users. Approximately one in five users had AAS dependence and experienced multiple adverse side effects. Few differences between users and non-users in self-reported mental health were found.

Conclusion

Findings indicate that AAS use among a community sample of Canadian adolescents and young adults is an important health issue, particularly given the relatively high occurrence of AAS dependence and adverse side effects reported by users. Findings support the need for education and intervention efforts from healthcare professionals. Further investigations among Canadian AAS users may provide more insight regarding the unique supports these individuals require.

The Somatomorphic Matrix-Female: More evidence for the validity of bidimensional figural rating scales for women

Our study aimed to develop and provide a preliminary psychometric validation of the Somatomorphic Matrix-Female (SM-F), a new bidimensional female figural rating scale which can be used to gauge actual and desired levels of both body fat and muscularity in a consolidated measure, as well as providing an index of actual-desired body discrepancy based on these measures. Across two studies undergraduate women (n Study 1 = 481; n Study 2 = 391) completed the Eating Disorder Examination-Questionnaire, the Body Shape Questionnaire-34, and the Depression Anxiety Stress Scales-21 (Study 1) and the Drive for Thinness Scale and the Drive for Muscularity Scale (Study 2), as well as the SM-F. Overall, the SM-F demonstrated sound content, concurrent, and convergent validity for actual and desired body fat, actual and desired muscularity, and their respective discrepancy scores.

Use of Legal Appearance- and Performance-Enhancing Drugs and Substances: Findings from the Canadian Study of Adolescent Health Behaviors

BACKGROUND

Use of appearance- and performance-enhancing drugs and substances (APEDS) is common among adolescent and young adults. Many APEDS are legally sold "over-the-counter," however research has documented contamination of legal APEDS and many adverse effects of use. Despite this, little research has been conducted on legal APEDS use in Canada, particularly regarding the prevalence and sociodemographic predictors of use, which was the aim of this study.

METHODS

Data from the Canadian Study of Adolescent Health Behaviors (N = 2,731) were analyzed. Prevalence and frequency of use of 10 common APEDS in the past 12 months were estimated overall and across genders. Multiple modified Poisson regression analyses were conducted to determine the sociodemographic predictors of APEDS use.

RESULTS

Overall, use of caffeine was most common among the sample (71.3%), along with protein bars (63.4%), and whey protein powders or protein shakes (63.1%). Boys and men reported greater prevalence of use of eight of the 10 APEDS, with the exception of diuretics or water pills and probiotics, compared to girls and women and transgender/gender non-confirming participants. Over three quarters (82.5%) of boys and men reported use of whey protein powders or protein shakes and 50.3% reported use of creatine monohydrate. Use of APEDS varied based on several key sociodemographic identifiers.

CONCLUSIONS

This study is the first to document legal APEDS use among a sample of Canadian adolescents and young adults, providing important implications for health care and policymaking professionals. Further research is needed to gain greater insight into APEDS use among Canadian young people.

"Bulking and cutting" among a national sample of Canadian adolescents and young adults

PURPOSE

First, to characterize the prevalence and incidence of "bulk" and "cut" cycles among Canadian adolescents and young adults. Second, to determine the associations between bulk and cut cycle engagement and drive for muscularity and eating disorder and muscle dysmorphia psychopathology.

METHODS

Data were from the Canadian Study of Adolescent Health Behaviors (2021; N = 2762), a national study of Canadian adolescents and young adults aged 16-30 years (M = 22.9, SD = 3.9). Prevalence and mean incidence of bulk and cut cycles in both the past 12 months and 30 days were estimated. Modified Poisson regressions were estimated to determine the associations between bulk and cut cycle engagement and levels of drive for muscularity and eating disorder and muscle dysmorphia psychopathology.

RESULTS

The sample comprised of 53.5% women, 38.4% men, and 8.1% transgender/gender non-conforming (TGNC) individuals. Nearly half (48.9%) of men and one in five women (21.2%) and TGNC (21.9%) participants reported bulk and cut cycles in the past 12 months. TGNC participants and women reported a greater mean number of bulk and cut cycles completed compared to men. Engagement in bulk and cut cycles was associated with stronger drive for muscularity across the sample, and more severe eating disorder and muscle dysmorphia psychopathology among men and women.

CONCLUSION

Findings underscore the common incidence and accompanying psychopathology of bulk and cut cycles among a community sample of adolescents and young adults in Canada, indicating the need for future research, as well as clinical and public health efforts.

LEVEL OF EVIDENCE

Level V, cross-sectional descriptive study.

Characterizing cheat meals among a national sample of Canadian adolescents and young adults

BACKGROUND

"Cheat meals", described as brief eating episodes that depart from established dietary practices to consume prohibited foods, represent a novel and increasingly common eating behavior with particular salience in adolescence and young adulthood. However, knowledge gaps remain regarding the frequency and characterization of foods and calories consumed during cheat meals, and their associations with eating disorder behaviors and psychopathology. Thus, the aims of this study were to delineate engagement in cheat meals among a large, national sample of Canadian adolescents and young adults.

METHODS

Participants (N = 2,717) were from the Canadian Study of Adolescent Health Behaviors. Frequencies of engagement in cheat meals, and associated foods and calories consumed, in the past 12 months and 30 days were determined. The associations between engagement in cheat meals and eating disorder behaviors and psychopathology were determined using modified Poisson regression analyses.

RESULTS

Engagement in cheat meals in the past 12 months was highest among men (60.9%) compared to women (53.7%) and transgender/gender non-conforming (TGNC; 52.5%) participants. Cheat meals consisting between 1,000 and 1,499 cal were those most frequently reported among all participants. Mean number of cheat meals in the past 12 months was equivalent to > 1 per week, which was similar to engagement in the past 30 days. Finally, engagement in cheat meals in the past 12 months and 30 days was associated with patterns of eating disorder behaviors and psychopathology among all participants, including binge-eating-related behaviors.

CONCLUSIONS

This study further characterized and extended knowledge of cheat meal engagement across genders, aligning with prior research by demonstrating that engagement is associated with greater eating disorder psychopathology. Findings from this study add to the growing characterization of the novel behavioral phenomenon of cheat meals. Specifically, over half of adolescents and young adults across all 13 provinces and territories in Canada reported engaging in > 1 cal dense cheat meal per week, over the past 12 months. Despite the normalization and promotion of cheat meal engagement among the general public and unique fitness communities, engagement in this behavior is linked to greater eating disorder behaviors and psychopathology, including binge-eating episodes. Our findings emphasize the need for further research, public awareness, and clinical interventions aimed at addressing this potentially harmful eating behavior.

Psychological Well-Being of Australian Actors and Performing Artists: Life Satisfaction and Negative Affect

BACKGROUND

Anecdotal evidence and media reports suggest that actors and other performing artists experience high levels of depression, anxiety, and stress. However, no empirical study has examined the psychological well-being of this professional group.

OBJECTIVE

The Australian Actors' Wellbeing Study (AWS) was conducted to examine the general wellbeing of Australian actors and performing artists. The present paper, reporting on data from the AWS, focuses on two aspects of respondents' psychological well-being: life satisfaction and the experience of negative affect.

METHODS

An online survey including several questionnaires was distributed to the Equity Foundation membership representing Australian actors. We report results from the Satisfaction with Life Scale (SWLS) and the Depression Anxiety Stress Scales (DASS) and examine their associations with respondents' sociodemographic and occupational background, including their relationship status and any relationship stress, income from performing, and time taken away from performing.

RESULTS

A sample of 782 Australian actors responded to the survey, with 582 participants completing the DASS and 568 the SWLS. Participants reported lower levels of life satisfaction and higher levels of depression, anxiety, and stress than found in the Australian general population. Being in a relationship was associated with better psychological well-being; however, work stress often impacted negatively on relationships. Income had little association with psychological well-being, unless the respondent felt under financial stress. Respondents who took extended periods of time away from performing reported less life satisfaction and more depression than others.

CONCLUSION

Australian actors may be at a high risk for poor psychological health. Further research is necessary to establish causality among the variables we examined and to investigate protective factors that may increase well-being in the context of the performing arts industry.

Weight gain attempts and substance use behaviors among adults across five countries

Weight gain attempts are common among adolescents, yet a paucity of research has explored these behaviors among adults, particularly in relation to substance use behaviors. To address this gap in the literature, pooled data from the 2018 and 2019 International Food Policy Study (N = 42,108) were analyzed. The association of weight gain attempts in the past 12 months with four important and relatively common substance use behaviors (alcohol use, binge-drinking, cigarette smoking, marijuana use) was examined using multiple modified Poisson regression analyses that adjusted for theoretically relevant covariates. Among men and women, weight gain attempts were associated with a higher likelihood of cigarette smoking in the past 30 days, marijuana use in the past 12 months, and binge-drinking one or more times per month in the past 12 months among men only. Among women, weight gain attempts were associated with a lower likelihood of alcohol use one or more times per month in the past 12 months. Our findings contribute to the literature demonstrating that substance use behaviors are more prevalent among adults who report weight gain attempts in a large international sample.

Compulsive exercise among college students: 5-year time trends in prevalence and demographic, substance use, and mental health correlates

PURPOSE

To provide 5-year time trends in prevalence and demographic, substance use, and mental health correlates of compulsive exercise among a national sample of college men and women.

METHODS

We analyzed 4 academic survey years (2016-2020; N = 8251) of the national (USA) Healthy Minds Study. Compulsive exercise was measured by self-report of any occurrence of "compulsive" exercise in the past 4 weeks. Unadjusted prevalence of compulsive exercise in the past 4 weeks was estimated across the 4 survey years by sex. Multiple logistic regression analyses were conducted among the pooled sample and stratified by sex to estimate the associations between compulsive exercise in the past 4 weeks and demographic, substance use, and mental health correlates.

RESULTS

Among the pooled sample, 11% (95% confidence interval [CI] 9.60-12.42%) of men and 17% (95% CI 15.86-18.24%) of women reported compulsive exercise in the past 4 weeks. Prevalence across the 4 survey years remained stable among men and women. Higher body mass index was associated with greater odds of any compulsive exercise in the past 4 weeks among men, while any sports participation was associated with greater odds of any compulsive exercise in the past 4 weeks among women. Compulsive exercise in the past 4 weeks was associated with greater odds of all mental health symptoms and illicit drug use among men and women, and higher odds of alcohol use among women.

CONCLUSION

Compulsive exercise is relatively common among college men and women and is associated with substance use behaviors and poor mental health symptoms.

LEVEL OF EVIDENCE

V, cross-sectional descriptive study.

Gender compatibility and drive for muscularity among adolescent boys: Examining the indirect effect of emotion regulation difficulties

The drive for muscularity continues to be a prominent concern among adolescent boys. However, it is unknown how gender compatibility (gender typicality and gender contentedness) relates to this pursuit. The present study sought to examine the link between gender compatibility and drive for muscularity among male adolescents, and whether this is partially accounted for by emotion regulation difficulties. Participants were 903 male adolescents, aged 11-19 years, who completed self-report measures as part of the EveryBODY study. Using path analysis, a proposed mediation model was assessed, testing an indirect pathway of gender compatibility and drive for muscularity through emotion regulation difficulties. Findings showed an indirect pathway between gender compatibility and drive for muscularity through emotion regulation difficulties. That is, boys who were more content with their male gender and believed they were typical of their gender reported fewer emotion regulation difficulties and, in turn, exhibited a lower drive for muscularity. Findings support theoretical perspectives integrating masculinity and muscularity in boys, in that those who feel less compatible with their masculinity could be susceptible to developing a greater drive for muscularity to regulate distress deriving from perceptions of not being sufficiently masculine. This study sets the groundwork for future longitudinal studies.

Emotion dysregulation across the span of eating disorder symptoms: Findings from a community sample of adolescents

OBJECTIVE

Emotion dysregulation is proposed as a key factor within eating disorder pathology. However, less is known about specific emotion regulation difficulties experienced by adolescents with varying levels of eating disorders symptoms. The present study examined the relationship between eating disorder behaviors and specific facets of emotion dysregulation, and differences in emotion dysregulation between eating disorder diagnostic groups.

METHOD

Participants were 2,783 adolescents, 11-19 years (M = 14 years, 9 months, SD = 1 year, 6 months), who completed self-report measures as part of the EveryBODY study. Adolescents were identified as not having eating disorder symptoms (n = 2,122) or meeting diagnostic criteria for symptoms of specific eating disorder, including: anorexia nervosa or atypical anorexia nervosa (n = 57), bulimia nervosa (n = 136), binge-eating disorder (n = 57), other specified feeding or eating disorder characterized by binge eating or purging (n = 381), and unspecified feeding or eating disorder (n = 30).

RESULTS

Binge eating, driven exercise, and fasting were each uniquely associated with emotion dysregulation, whereas purging was not. Similar findings were obtained within specific domains of emotion dysregulation. Findings from diagnostic groups showed a significant main effect of diagnosis on overall emotion dysregulation and most domains of emotion dysregulation. Adolescents with eating disorder symptoms consistently reported higher emotion dysregulation compared to those without these symptoms.

DISCUSSION

Findings indicate that emotion dysregulation is a key factor across eating disorder pathology, and potential treatment target across the spectrum of eating disorder diagnoses in adolescents.

Factor structure and psychometric properties of the Muscularity-Oriented Eating Test in university women in Australia

OBJECTIVE

Toned muscularity continues to emerge as a salient aspect of women's body image. However, there is a dearth of research investigating the potentially maladaptive eating practices and related cognitions that accompany the drive for muscularity in women. This may be attributable to the limited empirical and clinical attention previously given to muscularity-oriented disordered eating and, accordingly, the lack of validated measures assessing these concerns. To address this knowledge gap, our study aimed to provide a preliminary evaluation of the factor structure and core psychometric properties of a recently developed measure of muscularity-oriented disordered eating, the Muscularity-Oriented Eating Test (MOET), in university women in Australia.

METHOD

Participants included 419 university women who completed the 15-item MOET and other self-report measures for validity evaluation as part of an online survey. Data from split-half samples were used to undertake an exploratory factor analysis and subsequent confirmatory factor analysis.

RESULTS

Factor analytic results supported a briefer (12-item), one-factor scale in this sample of university women. The internal consistency reliability and validity (convergent and discriminant) of this 12-item unidimensional MOET was supported.

DISCUSSION

Our study provides preliminary support for this modified MOET as a psychometrically sound self-report measure of muscularity-oriented disordered eating in university women in Australia, providing a useful tool for understanding maladaptive eating behaviors and cognitions concomitant to the pursuit of muscularity in this population.

Prevalence and correlates of weight gain attempts across five countries

OBJECTIVE

To determine the prevalence and correlates of weight gain attempts in a pooled sample of adults aged 18 and older from Canada, Australia, the United Kingdom, the United States, and Mexico.

METHOD

Data collected during 2 years (2018 and 2019) of the International Food Policy Study (N = 42,108) were analyzed. Unadjusted 12-month prevalence of weight gain attempts was estimated based on body mass index (BMI; kg/m² ), weight perception, country, survey year, and sex. Logistic regression analyses were estimated to determine the sociodemographic correlates (age, race/ethnicity, education, BMI, weight perception, weight perception accuracy, and self-rated mental health) of weight gain attempts among the pooled sample stratified by sex.

RESULTS

Men (10.4%) were significantly more likely than women (5.4%) to report weight gain attempts (p < .001). Nearly one in five (17.1%) men with a BMI in the "normal" range (≥18.5 to <25.0) reported weight gain attempts. Among both men and women, minority group identity was associated with higher odds, while older age and higher BMI category were associated with lower odds, of reporting weight gain attempts. Country differences over the two survey years showed the prevalence of weight gain attempts in 2019 (vs. 2018) was higher among women in Australia (p < .05) and men in the United States (p < .01).

DISCUSSION

Weight gain attempts are more common among men, compared to women, across five countries, potentially reflecting the global salience of the pursuit of a muscular body.

Associations between legal performance-enhancing substance use and future cardiovascular disease risk factors in young adults: A prospective cohort study

BACKGROUND

Legal performance-enhancing substances (PES), such as creatine, are commonly used by adolescents and young adults. As PES are mostly unregulated by the US Food and Drug Administration, there has been limited empirical attention devoted to examining their long-term safety and health outcomes. Preliminary studies have demonstrated associations between PES use and severe medical events, including hospitalizations and death. PES could be linked to cardiovascular disease (CVD), the most common cause of mortality in the US, by altering the myocardium, vasculature, or metabolism. The objective of this study was to examine prospective associations between the use of legal PES in young adulthood and CVD risk factors at seven-year follow-up.

MATERIALS AND METHODS

Nationally representative longitudinal cohort data from the National Longitudinal Study of Adolescent to Adult Health, Waves III (2001-2002) and IV (2008), were analyzed. Regression models determined the prospective association between the use of legal PES (e.g. creatine monohydrate) and CVD risk factors (e.g. body mass index, diabetes, hypertension, hyperlipidemia), adjusting for relevant covariates.

RESULTS

Among the diverse sample of 11,996 male and female participants, no significant differences by PES use in body mass index, diabetes, hypertension, or hyperlipidemia were noted at Wave III. In unadjusted comparisons, legal PES users (versus non-users) were more likely to be White, be male, be college educated, drink alcohol, and engage in weightlifting, exercise, individual sports, team sports, and other strength training. There were no significant prospective associations between legal PES use at Wave III and body mass index, hemoglobin A1c, systolic and diastolic blood pressure, and cholesterol (total, HDL, LDL, triglycerides) deciles at seven-year follow-up (Wave IV), adjusting for demographics, health behaviors, and Wave III CVD risk factors. Similarly, there were no significant prospective associations between legal PES use and diabetes, hypertension, or hyperlipidemia based on objective measures or self-reported medications and diagnoses, adjusting for demographics, health behaviors, and Wave III CVD risk.

CONCLUSIONS

We do not find evidence for a prospective association between legal PES use and CVD risk factors in young adults over seven years of follow-up, including BMI, diabetes, hypertension, or hyperlipidemia. It should be noted that legal PES use was operationalized dichotomously and as one broad category, which did not account for frequency, amount, or duration of use. Given the lack of regulation and clinical trials data, observational studies can provide much needed data to inform the safety and long-term health associations of legal PES use and, in turn, inform clinical guidance and policy.

'Big boys don't cry': Examining the indirect pathway of masculinity discrepancy stress and muscle dysmorphia symptomatology through dimensions of emotion dysregulation

Prevailing conceptualizations of muscle dysmorphia (MD) have highlighted the role of adherence to stereotypical ideals of masculinity. In addition, the endorsement of masculine norms has been associated with dysfunctional emotional regulation, itself a correlate of body image psychopathology. Building on this, the present study sought to investigate the indirect relationship between masculinity discrepancy stress (i.e., distress related to one's perceived discrepancy in masculinity) and MD symptomatology via different facets of emotion dysregulation among adult men. A sample of 391 university and community men aged 18-50 years completed an online survey measuring the aforementioned constructs. A test of parallel indirect pathways revealed that emotion dysregulation, as a unitary construct, accounted for a substantial proportion (29.3 %) of the total association between masculinity discrepancy stress and MD symptomatology. Further, a significant unique indirect pathway was found through the specific emotion dysregulation facet of lack of access to adaptive emotion regulation strategies. Together, these findings suggest that emotion dysregulation is a particularly important construct to consider in understanding the relationship between perceived discrepancies in masculinity and MD symptomatology.

Who's the 'bigger' man? Parsing the relationships between masculinity and men's muscularity dissatisfaction

Muscularity dissatisfaction is documented to be a pervasive phenomenon among men. While previous studies have examined theoretically relevant predictors of muscularity dissatisfaction, such as adherence to traditional masculine norms, to the best of our knowledge we are not aware of empirical research that has assessed how perceived discrepancies in one's level of masculinity may also be associated with these concerns. Therefore, the objective of this study was to determine whether perceived deficits in masculinity bear predictive utility over and above adherence to traditional masculine norms in the context of muscularity dissatisfaction. An online survey that included measures assessing the aforementioned constructs was completed by 390 university and community adult men. A hierarchical regression analysis showed that while adherence to masculine norms was associated with increased muscularity dissatisfaction, masculine role discrepancy (and attendant stress) were particularly strong predictors of muscularity dissatisfaction. Our findings make a novel contribution to the male body image literature by demonstrating the relative importance of perceived discrepancies in masculinity, and related stress, in the context of muscularity dissatisfaction. Pending replication in relevant clinical samples using prospective designs, this study provides preliminary evidence that masculine role discrepancies may be promising targets to help allay muscularity concerns among men.

Alcohol Use by Australian Actors and Performing Artists: A Preliminary Examination from the Australian Actors' Wellbeing Study

BACKGROUND

Anecdotal and media reports suggest that actors and performing artists are vulnerable to high levels of alcohol use. However, little empirical research is available to document the extent and correlates of alcohol use amongst these artists, particularly in an Australian context.

OBJECTIVE

This study investigated alcohol use in a sample of Australian actors and other performing artists and its associations with sociodemographic background, psychological wellbeing, and work stress.

METHODS

An online survey was distributed to the Equity Foundation membership representing Australian actors and performing artists. The survey included questions on sociodemographic and occupational background and psychological wellbeing (DASS-21), as well as the AUDIT questionnaire to assess self-reported alcohol consumption. A sample of 620 performing artists responded to the survey, a large majority of whom were actors.

RESULTS

Australian actors and performing artists appear to consume alcohol at levels that are higher than those found in the general Australian population. About 40% of men and 31% of women were classified as drinking alcohol at potentially harmful or hazardous levels. Alcohol use was not strongly associated with age, education, or income, but it had a relationship with poorer psychological wellbeing. About 50% of respondents reported that their alcohol drinking was related to work stress as a performer. This perception was more pronounced amongst those performers who reported drinking at harmful levels.

CONCLUSIONS

Australian actors and performing artists appear to be an at-risk population for harmful or hazardous alcohol use.

An investigation of distress tolerance and difficulties in emotion regulation in the drive for muscularity among women

Despite the negative emotional experiences that often accompany the pursuit of an idealized appearance, we know little about emotion regulation in the context of female drive for muscularity. To address this knowledge gap, we examined whether distress tolerance and difficulties in emotion regulation were significantly associated with the drive for toned muscularity among women. In this study, 221 Australian university women completed an online survey assessing drive for muscularity, distress tolerance, and emotion regulation difficulties. Results revealed that low distress tolerance and emotion regulation difficulties were positively associated with drive for muscularity attitudes and behaviors, after controlling for body mass index and general negative affect. Our findings suggest that women with a range of distress tolerance and emotion regulation difficulties, particularly the urgent need to regulate, and non-acceptance of, distress may experience a higher drive for muscularity. This study provides preliminary evidence that specific aspects of distress tolerance and poor emotion regulation may be promising targets in prevention and treatment interventions aimed to address the excessive drive for muscularity among women.

Eating Disorder Symptoms in Australian Actors and Performing Artists

AIMS

Anecdotal evidence suggests that actors and other performing artists are under great pressure to conform to idealized appearances and body types. The pursuit of such appearances may trigger eating disorder symptoms, such as unhealthy attitudes towards body weight and shape. Thus far, there has been no dedicated empirical study of the prevalence of such problems in Australian actors and performing artists specifically. Therefore, this study sought to examine eating disorder symptomatology in Australian actors and performing artists.

METHODS

An online survey was distributed to the Equity Foundation membership representing Australian actors and performing artists, of whom 573 individuals completed the survey. This survey gauged demographic information and eating disorder symptoms using the psychometrically validated Eating Disorder Diagnostic Scale (EDDS).

RESULTS

A large proportion of actors reported unhealthy attitudes such as 'feeling fat' even though they are of normal weight or underweight; reported an extreme fear of gaining weight; and evaluated their self-worth based on their body weight and shape, particularly women. Results also showed that 2.5% of women in the study met the diagnostic criteria for anorexia nervosa and 13% met diagnostic criteria for bulimia nervosa based on their scores on the EDDS.

DISCUSSION

Performers may be a particularly at-risk population for the development and/or maintenance for a range of eating disorders.

Negative psychological correlates of the pursuit of muscularity among women

OBJECTIVE

There is increasing public and scientific focus on women's pursuit of a muscular and toned appearance. However, the psychological correlates of women's drive for muscularity are currently unclear. Therefore, we examined the associations of drive for muscularity with four important negative psychological indices among women: eating disorder (ED) symptoms, and symptoms of depression, anxiety, and stress.

METHOD

A sample of 221 university women completed an online survey that included measures assessing the aforementioned constructs.

RESULTS

Drive for muscularity evidenced positive associations with all negative psychological indices, except for anxiety. Muscularity-oriented attitudes, as opposed to behaviors, demonstrated the strongest associations with ED and depression symptoms.

DISCUSSION

Our findings make a novel contribution to the scant literature by demonstrating that women who endorse attitudes and/or behaviors geared toward attaining the female muscular ideal may be susceptible to experiencing ED symptoms and negative emotional states. This study provides preliminary evidence that muscularity-oriented attitudes, in particular, may be a promising target for the treatment of EDs and negative emotional states in women with a preoccupation toward muscularity.

Mobile phone conversation distraction: Understanding differences in impact between simulator and naturalistic driving studies

A current issue within the driver distraction community centres around different findings regarding the impact of mobile phone conversation on driving found in driving simulators versus instrumented vehicles employed in real-world naturalistic driving studies (NDSs). This paper compares and contrasts the two types of studies and aims to provide reasons for the differences in findings that have been documented. A comprehensive review of literature and consultations with human factors experts highlighted that simulator studies tend to show degradation in driving performance, suggestive of increased crash risk as a result of mobile phone conversation. Whilst NDSs, at times, present data suggesting that mobile phone conversation distraction actually reduces crash risk. This study identifies that these differences may be attributed to behavioural hypotheses associated with driver self-regulation, arousal from cognitive loading, task displacement and gaze concentration - all of which need to be explicitly tested in future driving studies. Metric estimation and application was also revealed to be polarising results and the subsequent assessment of the crash risk. A common metric applied in this domain is the 'Odds Ratio', particularly prevalent in NDSs. This study presents a detailed investigation into the assumptions and application of the Odds Ratio which revealed the potential for over- and under-estimation of the metric depending on the core data and sampling assumptions. Furthermore, this research presents a comparative analysis of select driving simulator studies and an NDS considering only driving behaviour data as a means to consistently compare the findings of both methodologies. The findings from this investigation implores the need for greater consistency in the application of analysis methods and metrics across both simulator and NDSs. Improvements can yield a more robust platform to systematically compare and interpret data across both approaches, ultimately leading to enhanced planning and safety regarding mobile phone use while driving.

Muscle Dysmorphia: An Overview of Clinical Features and Treatment Options

An increasing public and empirical focus on male body image indicates that muscularity is a preeminent concern among boys and men. For some, these concerns develop into a complex and disabling psychiatric disorder termedmuscle dysmorphia(MD), the hallmark of which is an intense preoccupation regarding one’s (subjectively) insufficient muscularity. Treatment of MD is critical; however, evidence to inform treatment approaches is sorely lacking. The purpose of this article is twofold. First, we provide an overview of the clinical features of MD, drawing particular attention to the preoccupation, functional impairment and psychiatric comorbidity associated with the disorder. Second, we discuss and recommend potential treatment directions for MD, including techniques that have demonstrated efficacy in the treatment of related disorders, namely, body dysmorphic disorder and eating disorders (and anorexia nervosa in particular). Psychotherapeutic techniques, including cognitive restructuring of deleterious perfectionistic and egosyntonic beliefs, and dialectical behavioral techniques to improve the repertoire of emotion regulation skills available to afflicted individuals, are discussed, in addition to psychopharmacological approaches.

Craniosynostosis and risk factors related to thyroid dysfunction

Thyroid disease is a common problem among women of reproductive age but often goes undiagnosed. Maternal thyroid disease has been associated with increased risk of craniosynostosis. We hypothesized that known risk factors for thyroid disease would be associated with risk of craniosynostosis among women not diagnosed with thyroid disease. Analyses included mothers of 1,067 cases and 8,494 population-based controls who were interviewed for the National Birth Defects Prevention Study. We used multivariable logistic regression to estimate adjusted odds ratios (AOR) and 95% confidence intervals (CI). After excluding women with diagnosed thyroid disease, younger maternal age (AOR 0.7, 95% CI 0.6-0.9, for <25 years versus 25-29), black or other race-ethnicity (AOR 0.3, 95% CI 0.2-0.4 and AOR 0.6, 95% CI 0.4-0.8, respectively, relative to non-Hispanic whites), fertility medications or procedures (AOR 1.5, 95% CI 1.2-2.0), and alcohol consumption (AOR 0.8, 95% CI 0.7-0.9) were associated with risk of craniosynostosis, based on confidence intervals that excluded 1.0. These associations with craniosynostosis are consistent with the direction of their association with thyroid dysfunction (i.e., younger age, black race-ethnicity and alcohol consumption are associated with reduced risk and fertility problems are associated with increased risk of thyroid disease). This study thus provides support for the hypothesis that risk factors associated with thyroid dysfunction are also associated with risk of craniosynostosis. Improved understanding of the potential association between maternal thyroid function and craniosynostosis among offspring is important given that craniosynostosis carries significant morbidity and that thyroid disease is under-diagnosed and potentially modifiable.

Three-dimensional head shape quantification for infants with and without deformational plagiocephaly

OBJECTIVE

The authors developed and tested three-dimensional (3D) indices for quantifying the severity of deformational plagiocephaly (DP).

DESIGN

The authors evaluated the extent to which infants with and without DP (as determined by clinic referral and two experts' ratings) could be correctly classified.

PARTICIPANTS

Infants aged 4 to 11 months, including 154 with diagnosed DP and 100 infants without a history of DP or other craniofacial condition. After excluding participants with discrepant expert ratings, data from 90 infants with DP and 50 infants without DP were retained.

MEASUREMENTS

Two-dimensional (2D) histograms of surface normal vector angles were extracted from 3D mesh data and used to compute the severity scores.

OUTCOME MEASURES

Left posterior flattening score (LPFS), right posterior flattening score (RPFS), asymmetry score (AS), absolute asymmetry score (AAS), and an approximation of a previously described 2D measure, the oblique cranial length ratio (aOCLR). Two-dimensional histograms localized the posterior flatness for each participant.

ANALYSIS

The authors fit receiver operating characteristic curves and calculated the area under the curves (AUC) to evaluate the relative accuracy of DP classification using the above measures.

RESULTS

The AUC statistics were AAS = 91%, LPFS = 97%, RPFS = 91%, AS = 99%, and aOCLR = 79%.

CONCLUSION

Novel 3D-based plagiocephaly posterior severity scores provided better sensitivity and specificity in the discrimination of plagiocephalic and typical head shapes than the 2D measurements provided by a close approximation of OCLR. These indices will allow for more precise quantification of the DP phenotype in future studies on the prevalence of this condition, which may lead to improved clinical care.

Transcriptome correlation analysis identifies two unique craniosynostosis subtypes associated with IRS1 activation

The discovery of causal mechanisms associated with nonsyndromic craniosynostosis has proven to be a difficult task due to the complex nature of the disease. In this study, differential transcriptome correlation analysis was used to identify two molecularly distinct subtypes of nonsyndromic craniosynostosis, termed subtype A and subtype B. In addition to unique correlation structure, subtype A was also associated with high IGF pathway expression, whereas subtype B was associated with high integrin expression. To identify a pathologic link between altered gene correlation/expression and the disease state, phosphorylation assays were performed on primary osteoblast cell lines derived from cases within subtype A or subtype B, as well as on primary osteoblast cell lines with novel IGF1R variants previously reported by our lab (Cunningham ML, Horst JA, Rieder MJ, Hing AV, Stanaway IB, Park SS, Samudrala R, Speltz ML. Am J Med Genet A 155A: 91-97, 2011). Elevated IRS1 (pan-tyr) and GSK3β (ser-9) phosphorylation were observed in two novel IGF1R variants with receptor L domain mutations. In subtype A, a hypomineralization phenotype coupled with decreased phosphorylation of IRS1 (ser-312), p38 (thr-180/tyr-182), and p70S6K (thr-412) was observed. In subtype B, decreased phosphorylation of IRS1 (ser-312) as well as increased phosphorylation of Akt (ser-473), GSK3β (ser-9), IGF1R (tyr-1135/tyr-1136), JNK (thr-183/tyr-187), p70S6K (thr-412), and pRPS6 (ser-235/ser-236) was observed, thus implicating the activation of IRS1-mediated Akt signaling in potentiating craniosynostosis in this subtype. Taken together, these results suggest that despite the stimulation of different pathways, activating phosphorylation patterns for IRS1 were consistent in cell lines from both subtypes and the IGF1R variants, thus implicating a key role for IRS1 in the pathogenesis of nonsyndromic craniosynostosis.

The Measurement of Monoamine Neurotransmitters in Microdialysis Perfusates Using HPLC-ECD

Microdialysis is a perfusion-based sampling procedure that is now used routinely to study the chemistry of the extracellular environment of a variety of tissues in the living organism (1,2). A microdialysis probe (consisting of an inlet and outlet tube connected by an area of semipermeable membrane) is perfused at a constant flow rate with a medium (artificial cerebrospinal fluid, CSF; aCSF) that is iso-osmotic to and contains ions at the same concentration as the extracellular fluid. Analytes pass through the semipermeable membrane down their concentration gradient and are swept through the probe by the constantly moving perfusion medium. Once collected, samples can then be analyzed by a variety of different analytical procedures.

Symbolic shape descriptors for classifying craniosynostosis deformations from skull imaging

Craniosynostosis is a serious condition of childhood, caused by the early fusion of the sutures of the skull. The resulting abnormal skull development can lead to severe deformities, increased intra-cranial pressure, as well as vision, hearing and breathing problems. In this work we develop a novel approach to accurately classify deformations caused by metopic and isolated sagittal synostosis. Our method combines a novel set of symbolic shape descriptors and off-the-shelf classification tools to model morphological variations that characterize the synostotic skull. We demonstrate the efficacy of our methodology in a series of large-scale classification experiments that contrast the performance of our proposed symbolic descriptors to those of traditional numeric descriptors, such as clinical severity indices, Fourier-based descriptors and cranial image quantifications.

Predicting neuropsychological development from skull imaging

Craniosynostosis is a serious and common pediatric disease caused by the premature fusion of sutures of the skull. Although studies have shown an increase in risk for cognitive deficits in patients with isolated craniosynostosis, the causal basis for this association is still unclear. It is hypothesized that an abnormally shaped skull produces a secondary deformation of the brain that results in the disruption of normal neuropsychological development. In this paper, we conduct a comparative analysis of our newly developed shape descriptors in an attempt to understand the impact of skull deformations on neurobehavior. In particular, we show that our scaphocephaly severity indices and symbolic shape signatures are predictive of mental ability and psychomotor functions, respectively, which suggests the possibility that secondary deformation could influence neuro-developmental status.

Differential Expression of CYP1A, 2B, and 3A Genes in the F344 Rat following Exposure to a Polybrominated Diphenyl Ether Mixture or Individual Components

Polybrominated diphenyl ethers (PBDEs), used as flame retardants, have been detected in the environment and in mammalian tissues and fluids. Evidence indicates that PBDE mixtures induce CYPs through aryl hydrocarbon receptor (AhR)-dependent and -independent pathways. The present work has investigated the effects of individual components of a commercial PBDE mixture (DE71) on expression of CYP1A1, a biomarker for activation of the AhR (dioxin-like), and CYP2B and CYP3A, biomarkers for activation of the constitutive androstane and pregnanexreceptors (CAR and PXR), respectively, in the rat. Male F344 rats were dosed orally on three consecutive days with either DE71, PBDE components, 2,2',4,4'-tetraBDE (BDE47), 2,2',4,4',5-pentaBDE (BDE99), 2,2',4,4',5,5'-hexaBDE (BDE153), representative polybrominated dibenzofurans (PBDFs) present in DE71, or reference PCBs. Differential expression of target genes was determined in liver 24 h after the last dose. Quantitative PCR analysis indicated up-regulation of CYP1A1 by DE71; however, the response was weak compared to that for dioxin-like PCB126. Individual PBDE components of DE71 up-regulated CYP1A1 only at the highest administered dose (100 micromol/kg/day). Representative PBDFs efficiently up-regulated CYP1A1; therefore, they, along with other PBDFs and polybrominated dibenzodioxins detected in DE71 and individual PBDE components, may be responsible for most, if not all, dioxin-like properties previously observed for PBDEs. Conversely, PBDEs appear capable of up-regulating CYP2B and CYP3A in rats at doses similar to that for non-dioxin-like PCB153. These results indicate that in vivo PBDE-mediated toxicity would be better categorized by AhR-independent mechanisms, rather than the well-characterized AhR-dependent mechanism associated with exposure to dioxin-like chemicals.

Correlation between thyroid hormone status and hepatic hyperplasia and hypertrophy caused by the peroxisome proliferator-activated receptor alpha agonist Wy-14,643

BACKGROUND: The metabolic inhibitor rotenone inhibits hepatocellular proliferation and the incidence of liver cancer resulting from exposure to the PPARalpha agonist Wy-14,643, via unknown mechanisms. Since the absence of thyroid hormones diminishes hepatomegaly, an early biomarker for the hepatocarcinogenicity induced by PPARalpha agonists, this study was undertaken to investigate whether rotenone might interference with the ability of Wy-14,643 to alter the animal thyroid status. METHODS: Male B6C3F1 mice were given Wy-14,643 (100 ppm), rotenone (600 ppm) or a mixture of both, in the feed for 7 days. Bromodeoxyuridine (BrDU), marker of cell replication, was delivered through subcutaneously implanted osmotic mini-pumps. At the end of the experiment, sera were collected and corticosterone and thyroid hormone levels were measured by solid-phase radioimmunoassay kits. In addition, liver tissue samples were stained immunohistochemically for BrDU to determine percentages of labeled cells. Further, cell surface area was determined from images generated by a Zeiss Axioplan microscope equipped with a plan Neofluar x40 0.75 na objective. Tracings of individual hepatocyte perimeters were then analyzed and cell-surface areas were calculated using MicroMeasure FL-4000. RESULTS: Wy-14,643 caused a significant increase in liver weights, hepatocyte BrDU labeling index (LI), and hepatocyte surface area. In animals which received both Wy-14,643 and rotenone simultaneously, all of these effects were significantly less pronounced compared with mice that received Wy-14,643 alone. Rotenone alone decreased liver weights, LI and surface area. The Free Thyroid Index (FTI), which provides an accurate reflection of the animal's thyroid status, was 5.0 +/- 0.3 in control mice. In animals exposed to rotenone, these values decreased to 2.0 +/- 0.9, but in animals which received Wy-14,643, levels increased significantly to 7.7 +/- 0.9. FTI values decreased to 3.4 +/- 0.8 in mice receiving both rotenone and Wy-14,643. CONCLUSION: A strong correlation was observed between the animal thyroid status and both, hepatocyte proliferation (r2 = 0.62), and hepatocyte surface area (r2 = 0.83). These results support the hypothesis that the thyroid status of the animal plays a role in PPARalpha-induced hepatocellular proliferation and liver cell enlargement. Both these events are known to contribute to the expression of liver cancer in response to the activation of PPARalpha.

Hepatic expression of polymerase beta, Ref-1, PCNA, and Bax in WY 14,643-exposed rats and hamsters

The hepatic levels of three protein markers of oxidative stress, polymerase beta, Ref-1, and PCNA, and of the pro-apoptotic protein, Bax, were quantitated after exposure to WY 14,643 (500 ppm in the feed) for 6 or 34 days in a rodent that is susceptible peroxisome proliferator (PP)-induced liver tumors (the Sprague Dawley rat) and in a rodent that is relatively resistant PP-induced liver tumors (the Syrian hamster). The analysis of detergent-extracted whole liver homogenates by immunoblotting showed a marked increase in the abundance of a 45-kDa variant of polymerase beta immunoreactivity and significant increases in the expression of Ref-1 and PCNA in WY 14,643-exposed rats. In contrast. WY 14,643-exposed hamsters expressed only trace levels of the polymerase beta variant and showed significant decreases in the expression of Ref-1 and PCNA. Long-term WY 14,643 exposure was associated with marked decreases in Bax expression in both species. Dose-response studies in the rat showed that the hepatic expression of the polymerase beta and Ref-1 were significantly increased after 6 days of exposure to WY 14,643 at levels of 5 and 50 ppm, respectively. The analysis of subcellular fractions of rat liver showed that the pathological increases in the levels of polymerase beta, Ref-1, and PCNA were especially prominent in mitochondria-enriched particulate liver subfractions. These results indicate that WY 14,643 exposure is associated with an increase in oxidative stress to the liver and that liver mitochondria are a major target of WY 14,643-associated liver damage. Our data are consistent with the hypothesis that the chronic overexpression of mutagenic or oncogenic effectors like polymerase beta and Ref-1 in a setting of increased hepatocyte proliferation and decreased apoptosis may facilitate peroxisome proliferator-induced hepatocellular carcinoma in the rat.

Determination of tamoxifen and metabolites in mouse fetal tissue using nonaqueous capillary electrophoresis

Tamoxifen (TAM), an antiestrogen, has been approved for use by women at risk for developing hormone-dependent breast cancer. Administration of TAM to pregnant CD-1 mice apparently results in reproductive tract toxicity in female offspring. However, there is little or no data describing potential TAM-induced fetal toxicity to women who may become pregnant while receiving prophylactic TAM treatment. In support of the National Toxicology Program's characterization of reproductive and developmental effects of TAM, the present work describes a capillary electrophoresis (CE)-based analytical technique used for detection of TAM and two major metabolites, N-desmethyltamoxifen (DMT), and 4-hydroxytamoxifen (4-HT) in CD-1 mouse fetal tissue. TAM-derived material was extracted from CD-1 mouse fetuses 2-12 h following TAM administration (100 mg/kg) to dams on gestation day 16. The presence of TAM, DMT, and 4-HT was confirmed in the solvent extracts by nonaqueous CE. The limit of detection of TAM by UV absorption was approximately 675 amol at a signal-to-noise ratio of 2:1. This work demonstrates both transplacental transport of TAM in CD-1 mice and a sensitive analytical technique for detecting low concentrations of TAM and similar compounds in biological tissues.

Another TWIST on Baller-Gerold syndrome

Baller-Gerold syndrome is characterized by craniosynostosis and preaxial upper limb malformations. Wide heterogeneity exists with regard to the presence of additional anomalies. Most of the 31 reported cases involve other malformations, including cardiac, Central Nervous System (CNS), and urogenital anomalies. Baller-Gerold syndrome is thought to have autosomal recessive inheritance. However, Gripp et al. [1999: Am. J. Med. Genet. 82:170-176] recently provided the first evidence for autosomal dominant inheritance with variable expressivity and severity. A nonsense mutation was found in TWIST, a gene associated with Saethre-Chotzen syndrome (SCS). Here we report on a male Caucasian patient of nonconsanguineous parents, with synostosis of the coronal, metopic, and sagittal sutures, and bilateral radial ray hypoplasia. The patient's small, round ears with prominent crus helices, and cervical anomalies are common features of SCS. The father had very mild features of SCS. We identify direct paternal transmission of a novel missense TWIST mutation in the highly conserved Helix II domain of this bHLH-family gene. This report lends further support to the recent findings by Gripp et al. [1999]. Future TWIST mutational analysis on patients with craniosynostosis and radial ray involvement will shed light on whether Baller-Gerold syndrome should be a distinct entity or some cases should be reclassified as a heterogeneous form of SCS.

Comparison of the mutant frequencies and mutation spectra of three non-genotoxic carcinogens, oxazepam, phenobarbital, and Wyeth 14,643, at the lambdacII locus in Big Blue transgenic mice

Oxazepam (OX), a widely used benzodiazepine anxiolytic, phenobarbital (PHE), a drug used for convulsive disorders, and Wyeth 14,643 (WY; [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio]acetic acid), a hypolipidemic agent, are all hepatocarcinogenic in B6C3F1 mice. They have been classified as "non-genotoxic" carcinogens since they are non-DNA reactive in in vitro assays and are either negative or weakly positive in Salmonella typhimurium (Ames assay). Male B6C3F1 Big Blue(R) transgenic mice were fed 2500 ppm of OX or PHE or 500 ppm of WY in their diet, while a control group of mice received diet alone for 180 days. The mutant frequency (MF) of cII in the control mice, after correction for clonality, was 6.2 +/- 2.8 x 10(-5). The MF values for mice fed OX, PHE, and WY were 10.0 +/- 3.6 x 10(-5) (P < 0.05), 7.9 +/- 1.3 x 10(-5) (P = 0.1) and 17.4 +/- 4.2 x 10(-5) (P < 0.01), respectively. The mutation spectrum (MS) at cII from the PHE-fed mice was significantly different (P < 0.05) from that of the control mice even though the MF was not, whereas the MS spectra of mice fed OX (P = 0.4) and WY (P = 0.7) were not significantly different. The PHE-derived spectrum differed from the spontaneous spectrum in the lower occurrence of G:C>C:G transversions (17 vs 1.6%) and the higher incidence of A:T>T:A transversions (3.4 vs 9.5%). Prior to correction for clonal expansion, each treated group exhibited a high incidence of frameshift mutations at the homopolymeric run of guanines at bp 179-184 (OX 21%, PHE 21%, WY 16% of the total mutations); this was not the case with the control group (6%). Even after clonal correction, more than 10% of the mutations were frameshifts in the treated mice, while 5% were frameshifts in the control mice. Despite this hypersensitive region of the gene, our findings suggest that the cII locus is less sensitive than the lacI locus to mutation induction by non-DNA reactive carcinogens.

Unilateral aplasia of the middle cranial fossa floor in atypical hemifacial microsomia

We present the first report of a patient with atypical hemifacial microsomia (HFM) and unilateral aplasia of the floor of the middle cranial fossa, glenoid fossa, and portions of her posterior fossa. The patient also developed a Chiari I malformation with cervical syrinx over a 3-year interval. This case report highlights the critical role of imaging in revealing serious, but clinically occult, structural abnormalities, as well as the evolution in the pathogenetic understanding of HFM.

Inhalation toxicity studies of the alpha,beta-unsaturated ketones: ethyl vinyl ketone

The National Toxicology Program is conducting a chemical class study to investigate the structure-activity relationships for the toxicity of alpha,beta-unsaturated ketones. Ethyl vinyl ketone (EVK) was selected for study because it is a representative straight-chain aliphatic alpha,beta-unsaturated ketone with extensive use and widespread exposure. Short-term inhalation studies of EVK were conducted to provide toxicity data for comparison with the related alpha,beta-unsaturated ketones 2-cyclohexene-1-one (CHX) and methyl vinyl ketone (MVK). These data will be used in designing chronic toxicity and carcinogenicity studies of these ketones. Male and female F344 rats and B6C3F1 mice were exposed to 0, 2, 4, or 8 ppm EVK 6 h/day, 5 days/wk for 13 wk. The nasal cavity was the major target organ of EVK in both rats and mice. Pathologic findings in both the olfactory and respiratory epithelium were observed. Lesions consisted primarily of olfactory epithelial necrosis, atrophy and regeneration, and/or hyperplasia and squamous metaplasia of the respiratory epithelium. Squamous metaplasia of the respiratory epithelium was present in all rats and mice exposed to 4 and 8 ppm EVK, and these lesions were more severe in rats than in mice. Few systemic effects were observed in rats and mice exposed to EVK. A transient decrease in total leukocytes due to decrements in lymphocyte and monocyte populations was present in male rats after exposure to 8 ppm for 3 and 21 days; however, this effect was not present after exposure for 13 wk. There were no chemical-related effects on micronucleus formation in mice, or on sperm motility and vaginal cytology in either species. EVK, like other alpha,beta-unsaturated ketones, is a reactive, direct-acting gaseous irritant with toxicity limited primarily to the upper respiratory tract.

Differential activation of hepatic NF-kappaB in rats and hamsters by the peroxisome proliferators Wy-14,643, gemfibrozil, and dibutyl phthalate

Nuclear factor-kappaB (NF-kappaB) is an oxidative stress-activated transcription factor involved in the regulation of cell proliferation and apoptosis. We found previously that the peroxisome proliferator ciprofibrate activates NF-kappaB in the livers of rats and mice. These species are sensitive to the hepatocarcinogenic effects of peroxisome proliferators, whereas other species such as Syrian hamsters are not. In the present study we examined the effects of 3 different peroxisome proliferators on NF-kappaB activation in rats and Syrian hamsters. The peroxisome proliferators Wy-14,643, gemfibrozil, and dibutyl phthalate were administered to animals for 6, 34, or 90 days. NF-kappaB activity was determined using electrophoretic mobility-shift assays and confirmed using supershift assays. Wy-14,643 increased the DNA binding activity of NF-kappaB at all 3 time points in rats and produced the highest activation of the 3 chemicals tested. Gemfibrozil and dibutyl phthalate increased NF-kappaB activation to a lesser extent in rats and not at all times. There were no differences in hepatic NF-kappaB levels between control hamsters and hamsters treated with any of the peroxisome proliferators. This study demonstrates species-specific differences in hepatic NF-kappaB activation by peroxisome proliferators.

Heterozygous mutations in ANKH, the human ortholog of the mouse progressive ankylosis gene, result in craniometaphyseal dysplasia

Craniometaphyseal dysplasia (CMD) is a bone dysplasia characterized by overgrowth and sclerosis of the craniofacial bones and abnormal modeling of the metaphyses of the tubular bones. Hyperostosis and sclerosis of the skull may lead to cranial nerve compressions resulting in hearing loss and facial palsy. An autosomal dominant form of the disorder (MIM 123000) was linked to chromosome 5p15.2-p14.1 (ref. 3) within a region harboring the human homolog (ANKH) of the mouse progressive ankylosis (ank) gene. The ANK protein spans the outer cell membrane and shuttles inorganic pyrophosphate (PPi), a major inhibitor of physiologic and pathologic calcification, bone mineralization and bone resorption. Here we carry out mutation analysis of ANKH, revealing six different mutations in eight of nine families. The mutations predict single amino acid substitutions, deletions or insertions. Using a helix prediction program, we propose for the ANK molecule 12 membrane-spanning helices with an alternate inside/out orientation and a central channel permitting the passage of PPi. The mutations occur at highly conserved amino acid residues presumed to be located in the cytosolic portion of the protein. Our results link the PPi channel ANK with bone formation and remodeling.

Regulation of differentiation to the infective stage of the protozoan parasite Leishmania major by tetrahydrobiopterin

A critical step in the infectious cycle of Leishmania is the differentiation of parasites within the sand fly vector to the highly infective metacyclic promastigote stage. Here, we establish tetrahydrobiopterin (H4B) levels as an important factor controlling the extent of metacyclogenesis. H4B levels decline substantially during normal development, and genetic or nutritional manipulations showed that low H4B caused elevated metacyclogenesis. Mutants lacking pteridine reductase 1 (PTR1) had low levels of H4B, remained infectious to mice, and induced larger cutaneous lesions (hypervirulence). Thus, the control of pteridine metabolism has relevance to the mechanism of Leishmania differentiation and the limitation of virulence during evolution.

Pteridine salvage throughout the Leishmania infectious cycle: implications for antifolate chemotherapy

Protozoan parasites of the trypanosomatid genus Leishmania are pteridine auxotrophs, and have evolved an elaborate and versatile pteridine salvage network capable of accumulating and reducing pteridines. This includes biopterin and folate transporters (BT1 and FT1), pteridine reductase (PTR1), and dihydrofolate reductase-thymidylate synthase (DHFR-TS). Notably, PTR1 is a novel alternative pteridine reductase whose activity is resistant to inhibition by standard antifolates. In cultured promastigote parasites, PTR1 can function as a metabolic by-pass under conditions of DHFR inhibition and thus reduce the efficacy of chemotherapy. To test whether pteridine salvage occurred in the infectious stage of the parasite, we examined several pathogenic species of Leishmania and the disease-causing amastigote stage that resides within human macrophages. To accomplish this we developed a new sensitive HPLC-based assay for PTR1 activity. These studies established the existence of the pteridine salvage pathway throughout the infectious cycle of Leishmania, including amastigotes. In general, activities were not well correlated with RNA transcript levels, suggesting the occurrence of at least two different modes of post-transcriptional regulation. Thus, pteridine salvage by amastigotes may account for the clinical inefficacy of antifolates against leishmaniasis, and ultimately provide insights into how this may be overcome in the future.

Effects of peroxisome proliferators on antioxidant enzymes and antioxidant vitamins in rats and hamsters

Peroxisome proliferators (PPs) cause hepatomegaly, peroxisome proliferation, and hepatocarcinogenesis in rats and mice, whereas hamsters are less responsive to PPs. PPs increase the activities of enzymes involved in peroxisomal beta-oxidation and omega-hydroxylation of fatty acids, which has been hypothesized to result in oxidative stress. The hypothesis of this study was that differential modulation of antioxidant enzymes and vitamins might account for differences in species susceptibility to PPs. Accordingly, we measured the activities of DT-diaphorase and superoxide dismutase (SOD) and the hepatic content of ascorbic acid and alpha-tocopherol in male Sprague-Dawley rats and Syrian hamsters fed 2 doses of 3 known peroxisome proliferators (dibutyl phthalate [DBP], gemfibrozil, and [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio]acetic acid (Wy-14,643) for 6, 34, or 90 days. In untreated animals, the activity of DT-diaphorase was much higher in hamsters than in rats, but the control levels of SOD, ascorbic acid and alpha-tocopherol were similar. In rats and hamsters treated with Wy-14,643, we observed decreases in alpha-tocopherol content and total SOD activity. DT-diaphorase was decreased in activity following Wy-14,643 treatment in rats at all time points and doses, but only sporadically affected in hamsters. Rats and hamsters treated with DBP demonstrated increased SOD activity at 6 days; however, in the rat, DBP decreased SOD activity at 90 days and alpha-tocopherol content was decreased throughout. In gemfibrozil treated rats and hamsters, a decrease in alpha-tocopherol content and an increase in DT-diaphorase activity were observed. In either species, no consistent trend was observed in total ascorbic acid content after treatment with any of the PPs. In conclusion, these data suggest that both rats and hamsters are compromised in antioxidant capabilities following PP treatment and additional hypotheses for species susceptibility should be considered.

14-Week toxicity and cell proliferation of methyleugenol administered by gavage to F344 rats and B6C3F1 mice

Methyleugenol, a food flavor and fragrance agent, was tested for toxicity in male and female F344/N rats and B6C3F1 mice. Groups of 10 males and 10 females per sex per species were administered 0, 10, 30, 100, 300 or 1000 mg methyleugenol/kg body weight in 0.5% aqueous methylcellulose by gavage, 5 days per week for 14 weeks. Additional groups of rats and mice of each sex were dosed similarly and used for hematology and clinical chemistry studies. Groups of 10 male and 10 female rats and mice received the vehicle by gavage on the same dosing schedule and served as vehicle controls. For serum gastrin, gastric pH and cell proliferation studies groups of 10 female rats were given 0, 37, 75 or 150 mg/kg, once daily 5 days per week for 30 or 90 days or 300 or 1000 mg/kg for 30 days; male mice were given 0, 9, 18.5, 37, 75, 150 or 300 mg/kg for 30 or 90 days. For the gastrin, pH and cell proliferation studies, groups of 10 female rats and 10 male mice were given the vehicle for 30 or 90 days and served as controls. Methyleugenol administration to rats induced erythrocyte microcytosis and thrombocytosis in male and female rats. It also caused an increase in serum alanine aminotransferase and sorbitol dehydrogenase activities and bile acid concentration, suggesting hepatocellular injury, cholestasis or altered hepatic function. Additionally, methyleugenol induced hypoproteinemia and hypoalbuminemia, evidenced by decreased total protein and albumin concentrations in both male and female rats, suggesting in inefficiency of dietary protein utilization due to methyleugenol-induced toxic effects on the liver and glandular stomach of rats and mice. The increase in gastrin and gastric pH of rats and mice given methyleugenol suggests that gastrin feedback was impaired and resulted in conditions not conducive to protein digestion. In rats, methyleugenol caused an increase in the incidences of hepatocyte cytologic alteration, cytomegaly, Kupffer cell pigmentation, mixed foci of cellular alteration and bile duct hyperplasia of the liver and atrophy and chronic inflammation of the mucosa of the glandular stomach. In mice, it caused an increase in the incidence of cytologic alteration, necrosis, bile duct hyperplasia and subacute inflammation of the liver and atrophy, degeneration, necrosis, edema, mitotic alteration, and cystic glands of the fundic region of the glandular stomach. The increased incidences of adrenal gland cortical hypertrophy and/or cytoplasmic alteration in the submandibular salivary glands, adrenal glands, testis and uterus of rats were considered secondary to the chemical-related effects observed in the liver and glandular stomach. Based on mortality, body weight gain, clinical chemistry and gross and microscopic evaluation of tissues of rats and mice, the no-observed-effect level (NOEL) of methyleugenol for both species was estimated at 10 mg/kg.

New models for assessing carcinogenesis: an ongoing process

Traditionally, the use of rodent models in assessing the carcinogenic potential of chemicals has been expensive and lengthy, and the relevance of the carcinogenic effect to humans is often not fully understood. Today, however, with the rapid advances in molecular biology, genetically altered mice containing genes relevant to humans (e.g. oncogenes, tumor suppressor genes) and reporter genes (e.g. lacI) provide powerful tools for examining specific chemical-gene interactions thereby allowing a better understanding of the mechanisms of carcinogenesis in a shorter period of time. This paper will cover an overview of ongoing validation efforts, followed by examples of studies using several genetically engineered models including the p53def mouse model and the Big Blue transgenic mouse model. Specifically, examples where transgenic models were integrated into the testing program based on specific hypotheses dealing with genetic alterations in cancer genes and reporter genes will be discussed. The examples will highlight possible ways genetically altered mice may be integrated into a comprehensive research and testing strategy and thereby provide an improved estimation of human health risks.