Longer-Term Mental Health Consequences of COVID-19 Infection: Moderation by Race and Socioeconomic Status

OBJECTIVE

While evidence suggests that the mental health symptoms of COVID-19 can persist for several months following infection, little is known about the longer-term mental health effects and whether certain sociodemographic groups may be particularly impacted. This cross-sectional study aimed to characterize the longer-term mental health consequences of COVID-19 infection and examine whether such consequences are more pronounced in Black people and people with lower socioeconomic status.

METHODS

277 Black and White adults (age ≥ 30 years) with a history of COVID-19 (tested positive ≥ 6 months prior to participation) or no history of COVID-19 infection completed a 45-minute online questionnaire battery.

RESULTS

People with a history of COVID-19 had greater depressive (d = 0.24), anxiety (d = 0.34), post-traumatic stress disorder (PTSD) (d = 0.32), and insomnia (d = 0.31) symptoms than those without a history of COVID-19. These differences remained for anxiety, PTSD, and insomnia symptoms after adjusting for age, sex, race, education, income, employment status, body mass index, and smoking status. No differences were detected for perceived stress and general psychopathology. People with a history of COVID-19 had more than double the odds of clinically significant symptoms of anxiety (OR = 2.22) and PTSD (OR = 2.40). Education, but not race, income, or employment status, moderated relationships of interest such that COVID-19 status was more strongly and positively associated with all the mental health outcomes for those with fewer years of education.

CONCLUSION

The mental health consequences of COVID-19 may be significant, widespread, and persistent for at least 6 months post-infection and may increase as years of education decreases.

Effect of modernized collaborative care for depression on brain-derived neurotrophic factor (BDNF) and depressive symptom clusters: Data from the eIMPACT trial

Brain-derived neurotrophic factor (BDNF) levels are lower in people with depression and are normalized following pharmacological treatment. However, it is unknown if psychological treatments for depression improve BDNF and if change in BDNF is a mediator of intervention effects on depressive symptoms. Therefore, using data from the eIMPACT trial, we sought to determine the effect of modernized collaborative care for depression on 12-month changes in BDNF and cognitive/affective and somatic depressive symptom clusters and to examine whether BDNF changes mediate intervention effects on depressive symptoms. 216 primary care patients with depression from a safety net healthcare system were randomized to 12 months of the eIMPACT intervention (internet cognitive-behavioral therapy [CBT], telephonic CBT, and select antidepressant medications) or usual primary care. Plasma BDNF was measured with commercially available kits, and depressive symptom clusters were assessed by the Patient Health Questionnaire-9. The intervention did not influence BDNF but did improve both the cognitive/affective and somatic clusters over 12 months. Changes in BDNF did not mediate the intervention effect on either cluster. Our findings suggest that modernized collaborative care is an effective treatment for both the cognitive/affective and somatic symptoms of depression and that the mechanism of action is not improvements in BDNF. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02458690.

Analgesic effects of alcohol in adults with chronic jaw pain

BACKGROUND

Although recent literature provides promising support for the analgesic properties of alcohol, potential differences in alcohol analgesia as a function of chronic pain status are not well understood. Thus, this study examined chronic pain status as a potential moderator of alcohol analgesia and distinguished between multiple aspects of pain experience and sensitivity: pain threshold, pain intensity, pain unpleasantness, and perceived relief.

METHODS

Social drinkers with (N = 19) and without (N = 29) chronic jaw pain completed two testing sessions in a counterbalanced order: alcohol (target BrAC = 0.08 g/dl) and placebo. In each, pressure algometry was performed at the insertion of the masseter. Alcohol analgesia was assessed by examining the main and interactive effects of beverage condition, pressure level (4, 5, or 6 pound-feet [lbf]), and chronic jaw pain status (chronic pain vs. pain-free control) on quantitative sensory testing measures and pain relief ratings following noxious stimuli.

RESULTS

Analyses indicated significant increases in pain threshold and pain relief and reductions in pain unpleasantness and pain intensity, under the alcohol condition. Chronic pain participants demonstrated lower pain thresholds and greater pain intensity and pain unpleasantness ratings than controls. There were no interactive effects of alcohol and pain conditions on any pain measure.

CONCLUSIONS

Findings provide experimental evidence of alcohol's analgesic and pain-relieving effects and suggest that these effects do not significantly differ by chronic pain status. Individuals, who self-medicate pain via alcohol consumption, irrespective of pain status, may be at increased risk to engage in hazardous drinking patterns and thus experience adverse alcohol-related consequences.

Acute Tolerance to the Analgesic Effects of Alcohol

OBJECTIVE

The goal of this study was to determine whether the acute analgesic effects of alcohol intake are moderated by acute alcohol tolerance, characterized by differing subjective and neurobehavioral effects of a given blood alcohol concentration (BAC) depending on whether BAC is rising or falling.

METHOD

Twenty-nine healthy drinkers (20 women) completed two laboratory sessions in which they consumed a study beverage: active alcohol (target BAC= .08 g/dl) and placebo. Acute alcohol tolerance was assessed by examining the main and interactive effects of beverage condition and assessment limb (ascending vs. descending) on quantitative sensory testing measures collected using slowly ramping heat stimuli and perceived relief ratings at comparable breath alcohol concentrations on the ascending and descending limbs.

RESULTS

BAC limb moderated the effect of condition on pain threshold, such that the threshold was significantly elevated in the alcohol condition on the ascending limb. The alcohol condition produced greater ratings of perceived pain relief than the placebo condition, and pain relief ratings were greater on the ascending versus descending limb of the BAC curve. Alcohol intake did not significantly affect pain tolerance or aftersensation ratings on either BAC limb.

CONCLUSIONS

This study provides initial experimental evidence that alcohol's analgesic and pain-relieving effects are subject to acute tolerance following acute alcohol intake. These findings suggest that self-medicating pain via alcohol intake may be associated with high-risk drinking topography, increasing the risk for alcohol-related consequences. Further research is needed to determine if these effects extend to the context of clinical and chronic pain.

Acute Tolerance to the Analgesic Effects of Alcohol

OBJECTIVE

The goal of this study was to determine whether the acute analgesic effects of alcohol intake are moderated by acute alcohol tolerance, characterized by differing subjective and neurobehavioral effects of a given blood alcohol concentration (BAC) depending on whether BAC is rising or falling.

METHOD

Twenty-nine healthy drinkers (20 women) completed two laboratory sessions in which they consumed a study beverage: active alcohol (target BAC= .08 g/dl) and placebo. Acute alcohol tolerance was assessed by examining the main and interactive effects of beverage condition and assessment limb (ascending vs. descending) on quantitative sensory testing measures collected using slowly ramping heat stimuli and perceived relief ratings at comparable breath alcohol concentrations on the ascending and descending limbs.

RESULTS

BAC limb moderated the effect of condition on pain threshold, such that the threshold was significantly elevated in the alcohol condition on the ascending limb. The alcohol condition produced greater ratings of perceived pain relief than the placebo condition, and pain relief ratings were greater on the ascending versus descending limb of the BAC curve. Alcohol intake did not significantly affect pain tolerance or aftersensation ratings on either BAC limb.

CONCLUSIONS

This study provides initial experimental evidence that alcohol's analgesic and pain-relieving effects are subject to acute tolerance following acute alcohol intake. These findings suggest that self-medicating pain via alcohol intake may be associated with high-risk drinking topography, increasing the risk for alcohol-related consequences. Further research is needed to determine if these effects extend to the context of clinical and chronic pain.

Assessment of Student Perspectives on Improving Wellness in Medical School: Qualitative Results from a Cross-Sectional Survey of Medical Students in Florida

PURPOSE

Helping medical students maintain wellbeing has become an important concern, as many medical students report a decline in their mental health during the course of their training. To improve students' wellbeing, some schools have implemented wellness programs into their curricula. While there is growing research about the effectiveness of these programs, little is known about what medical students themselves desire to support their wellbeing. This study aimed to assess medical student perspectives regarding the most effective ways to promote wellness during medical school.

PARTICIPANTS AND METHODS

To address this gap in the literature, a survey was administered to medical students at the nine medical schools in the state of Florida. Participants included 864 medical students, whose anonymous responses were analyzed descriptively as well as qualitatively to determine major themes.

RESULTS

Students provided novel suggestions and recommendations, including ideas for curricular additions and changes, cultural changes within schools, promoting positive behaviors and extracurricular activities, and providing resources for students.

CONCLUSION

Based on the participants' responses, it is evident that wellness is an important issue to medical students and, given the variety of suggestions, schools should strongly consider what wellness changes to implement and whether participation in them should be mandatory. The results of this study will be a resource to medical schools and educators who are considering curricular changes to address medical student wellbeing.

Development of emotion regulation across the first two years of college

INTRODUCTION

Emotion regulation is thought to develop substantially from late adolescence into early adulthood; further, the rate of development purportedly varies based on personal and contextual characteristics. However, little research has explicitly documented this maturation in young adulthood or identified its determinants. We aimed to (1) characterize how adaptive (positive reappraisal, emotional social support-seeking) and maladaptive (suppression, substance use coping) emotion regulation strategies changed over time and (2) predict change in each strategy based on baseline personal, social, and motivational characteristics.

METHODS

We followed a sample of 1578 students entering university in the northeastern United States across their first two years, assessing them four times.

RESULTS

As expected, social support-seeking increased and suppression decreased. However, contrary to expectations, cognitive reappraisal declined over time while substance use coping increased. Women generally used more adaptive emotion regulation strategies than did men; social engagement and connection and eudaimonic well-being were generally predictive of using more adaptive coping over time.

CONCLUSIONS

Overall, students did not consistently demonstrate maturation to more adaptive emotion regulation and in fact exhibited decrements over the first two years of college. Students' baseline characteristics accounted for substantial degrees of change in emotion regulation. These findings suggest potentially fruitful directions for interventions to assist college students in developing more adaptive emotion regulation skills.

0838 Sex Specific Changes in Sleep Macro-Structure With Obstructive Sleep Apnea in a Large Clinical Population of Older Adults

Introduction

Sleep architecture is influenced by age and sex and is disrupted by obstructive sleep apnea (OSA) and periodic limb movements (PLM) of sleep. Although increasing OSA severity is thought to decrease both REM and slow wave sleep (SWS), it may do so in non-linear ways. Here, we aim to 1) compare sleep macrostructure between older men and women, 2) compare metrics of total and REM-specific OSA severity between older men and women, and 3) examine associations between metrics of OSA severity and REM sleep and SWS in a clinical sample.

Methods

Clinical in-lab diagnostic polysomnography (PSG) in adults ≥64 years of age from the greater New York area recorded between 2006- 2016 were collated including demographic and traditional sleep scoring metrics. Studies where TST < 4 hours were removed. Demographic, sleep macrostructure, OSA (AHI4% & AHI3A criteria), pulse oximetry (SpO2) nadir and PLM measures were compared according to sex.

Results

PSGs from 1282 older adults (average age 70 years in both sexes, 41% female) were included in the analyses. Women had a significantly greater SWS% (14.5 vs 7.9, p<0.001) and less N1% (18.2 vs 24.4, p<0.001), without significant differences in TST, N2%, REM%, sleep efficiency or SpO2 nadir. Men had significantly higher all-sleep OSA (median AHI4% 8.8 vs 11.1, p=0.0004; median AHI3A 24.4 vs 27.9, p=0.003) and PLM’s (4.0 vs 7.6/hour, p=0.008) but women had significantly more OSA during REM sleep (median REM AHI4% 16.7 vs 14.0, p=0.01; median REM AHI3A 32.6 vs 27.4, p=0.0002). Inverse non-linear associations were observed between OSA severity and %SWS and %REM with a unique pattern for each sleep stage. The pattern between men and women within each stage appeared similar.

Conclusion

In this clinical sample of older adults, women exhibit a greater proportion of SWS and worse REM-related OSA then men. Increasing OSA severity is associated with non-linear reductions in %SWS and %REM, and we plan to further investigate these relationships and sexual dimorphism by using quantitative analysis of PSG signals for more precise measures of slow wave activity and breathing physiology than traditional sleep scoring metrics.

Support

R01AG056682

Promoting Resilience in Medicine: The Effects of a Mind-Body Medicine Elective to Improve Medical Student Well-being

Background

Poor mental health is common among medical students. In response, some medical schools have implemented wellness interventions. The University of Florida College of Medicine recently introduced a mind–body medicine elective, Promoting Resilience in Medicine (PRIMe), based on the Georgetown University School of Medicine course. PRIMe teaches meditation techniques including mindfulness, biofeedback, art, and journaling in a faculty-facilitated small group setting.

Methods

First- and second-year medical students (N = 24) who participated in the 11-week elective (3 cohorts over 2 years) completed anonymous surveys regarding their experiences. Measures included the Freiberg Mindfulness Inventory (FMI), Perceived Stress Scale-10 item (PSS-10), and a series of multiple-choice and free-response questions developed for this study. The study was approved by the University of Florida Institutional Review Board.

Results

Among students with available pre- and posttest scores, the average PSS-10 score at pretest was 14.4 (SD = 6.17, range = 3–26) and at posttest was 14.2 (SD = 4.17, range = 8–22), suggesting no change in perceived stress. However, average scores on the FMI improved from 34.4 (SD = 6.10, range = 24–47) at pretest to 41.8 (SD = 4.81, range = 33–49) at posttest. The overwhelming majority of participants (95.8%) described the course as “definitely” worth it. The greatest improvements were noted in mindfulness, relationships with peers, and having a safe place in medical school to receive support. Learning mindfulness/meditation skills and increasing social support were noted as the primary factors impacting student well-being.

Conclusion

A mind–body medicine elective course may be a practical method to improve medical student well-being and improve ability to care for patients. Future studies should include follow-up testing to determine if benefits are sustained over time. In addition, more work is needed to understand the cost–benefit of providing instruction in mind–body medicine techniques to all medical students.

Visible and Concealable Stigmatized Identities and Mental Health: Experiences of Racial Discrimination and Anticipated Stigma

Experiencing and anticipating discrimination because one possesses a visible (e.g., race) or concealable (e.g., mental illness) stigmatized identity has been related to increased psychological distress. Little research, however, has examined whether experiencing and anticipating discrimination related to possessing both a visible and concealable stigmatized identity (e.g., a racial/ethnic minority with a history of mental illness) impacts mental health. In the current study, we test two hypotheses. In the first, we examine whether experienced discrimination due to a visible stigma (race/ethnicity) and anticipating stigma due to a concealable stigma (e.g., substance abuse) each predict unique variance in depressive symptomatology. In the second, we examine whether experienced discrimination due to a visible stigma is related to greater anticipated stigma for a concealable stigma, which in turn is related to more depression. A total of 265 African American and Latinx adults who reported concealing a stigmatized identity at least some of the time completed measures of racial/ethnic discrimination, anticipated stigma of a concealable stigmatized identity, and depressive symptomatology. Results of a simultaneous linear regression revealed that increased racial/ethnic discrimination and anticipated stigma independently predicted greater depressive symptomatology (controlling for each other). A mediation analysis showed that the positive association between increased racial/ethnic discrimination and higher depressive symptomatology was partially mediated by greater anticipated stigma. These results demonstrate that a person can experience increased psychological distress from multiple types of stigma separately, but also may anticipate greater stigma based on previous experiences of racial discrimination, which in turn relates to increased distress.

Out and healthy: Being more “out” about a concealable stigmatized identity may boost the health benefits of social support

This research examined whether the relationship between perceived social support and health would be moderated by level of outness for people living with different concealable stigmatized identities (mental illness, substance abuse, domestic violence, rape, or childhood abuse). A total of 394 people living with a concealable stigmatized identity completed a survey. Consistent with hypotheses, at high levels of outness, social support predicted better health; at low levels of outness, social support was less predictive of health. People concealing a stigmatized identity may only be able to reap the health benefits of social support if they are “out” about the stigmatized identity.

From discrimination to internalized mental illness stigma: The mediating roles of anticipated discrimination and anticipated stigma

OBJECTIVE

Internalizing mental illness stigma is related to poorer well-being, but less is known about the factors that predict levels of internalized stigma. This study explored how experiences of discrimination relate to greater anticipation of discrimination and devaluation in the future and how anticipation of stigma in turn predicts greater stigma internalization.

METHOD

Participants were 105 adults with mental illness who self-reported their experiences of discrimination based on their mental illness, their anticipation of discrimination and social devaluation from others in the future, and their level of internalized stigma. Participants were approached in several locations and completed surveys on laptop computers.

RESULTS

Correlational analyses indicated that more experiences of discrimination due to one's mental illness were related to increased anticipated discrimination in the future, increased anticipated social stigma from others, and greater internalized stigma. Multiple serial mediator analyses showed that the effect of experiences of discrimination on internalized stigma was fully mediated by increased anticipated discrimination and anticipated stigma.

CONCLUSION AND IMPLICATIONS FOR PRACTICE

Experiences of discrimination over one's lifetime may influence not only how much future discrimination people with mental illness are concerned with but also how much they internalize negative feelings about the self. Mental health professionals may need to address concerns with future discrimination and devaluation in order to decrease internalized stigma.

Good Choices, Poor Choices: Relationship Between the Quality of Identity Commitments and Psychosocial Functioning

Research indicates making identity commitments on the part of emerging adults is associated with a wide range of psychosocial benefits. Data from a large research collaborative were used to evaluate hypotheses drawn from eudaimonic identity theory that the benefits of commitment are attributable to the quality of the commitments held. Findings from a study with 9,650 students attending 30 colleges and universities replicated previous research indicating the benefits of identity commitments with respect to subjective well-being, psychological well-being, self-esteem, an internal locus of control; and reduced likelihood of symptoms of general anxiety, social anxiety, and depression. However, when a measure of the quality of identity commitments was added to the analyses, results indicated that commitment quality accounted almost entirely for the associations of identity commitments with psychosocial functioning. Identity commitments of low quality were found to be associated with psychological costs rather than benefits. Implications for helping emerging adults distinguish better identity choices are discussed.

Acculturation and well-being among college students from immigrant families

OBJECTIVE

The present study was designed to ascertain the associations between acculturation and well-being in first-generation and second-generation immigrant college students. Acculturation was operationalized as a multidimensional construct comprised of heritage and American cultural practices, values (individualism and collectivism), and identifications, and well-being was operationalized in terms of subjective, psychological, and eudaimonic components.

METHOD

Participants were 2,774 first-generation and second-generation immigrant students (70% women), from 6 ethnic groups and from 30 colleges and universities around the United States. Participants completed measures of heritage and American cultural practices, values, and identifications, as well as of subjective, psychological, and eudaimonic well-being.

RESULTS

Findings indicated that individualistic values were positively related to psychological and eudaimonic well-being, and positively, although somewhat less strongly, linked with subjective well-being. American and heritage identifications were both modestly related to psychological and eudaimonic well-being. These findings were consistent across gender, immigrant generation (first versus second), and ethnicity.

CONCLUSIONS

Psychological and eudaimonic well-being appear to be inherently individualistic conceptions of happiness, and endorsement of individualistic values appears linked with these forms of well-being. Attachments to a cultural group-the United States, one's country of origin, or both-appear to promote psychological and eudaimonic well-being as well. The present findings suggest that similar strategies can be used to promote well-being for both male and female students, for students from various ethnic backgrounds, and for both first-generation and second-generation immigrant students.

Acculturation and Well-Being Among College Students From Immigrant Families

OBJECTIVE: The present study was designed to ascertain the associations between acculturation and well-being in first-generation and second-generation immigrant college students. Acculturation was operationalized as a multidimensional construct comprised of heritage and American cultural practices, values (individualism and collectivism), and identifications, and well-being was operationalized in terms of subjective, psychological, and eudaimonic components. METHOD: Participants were 2,774 first-generation and second-generation immigrant students (70% women), from 6 ethnic groups and from 30 colleges and universities around the United States. Participants completed measures of heritage and American cultural practices, values, and identifications, as well as of subjective, psychological, and eudaimonic well-being. RESULTS: Findings indicated that individualistic values were positively related to psychological and eudaimonic well-being, and positively, although somewhat less strongly, linked with subjective well-being. American and heritage identifications were both modestly related to psychological and eudaimonic well-being. These findings were consistent across gender, immigrant generation (first versus second), and ethnicity. CONCLUSIONS: Psychological and eudaimonic well-being appear to be inherently individualistic conceptions of happiness, and endorsement of individualistic values appears linked with these forms of well-being. Attachments to a cultural group-the United States, one's country of origin, or both-appear to promote psychological and eudaimonic well-being as well. The present findings suggest that similar strategies can be used to promote well-being for both male and female students, for students from various ethnic backgrounds, and for both first-generation and second-generation immigrant students. © 2012 Wiley Periodicals, Inc. J. Clin. Psychol. 00:1-21, 2012.

Identity consolidation and health risk behaviors in college students

OBJECTIVES

To investigate the protective role of personal identity consolidation against health risk behaviors in college-attending emerging adults.

METHODS

A multisite sample of 1546 college students completed measures of personal identity consolidation and recent risk behavior engagement.

RESULTS

Multivariate Poisson regression indicated that personal identity consolidation was negatively related to binge drinking, illicit drug use, sexual risk behaviors, and risky driving. These findings were consistent across gender, ethnicity, and place of residence.

CONCLUSIONS

A consolidated sense of personal identity may protect college-attending emerging adults from health-compromising behaviors. Health professionals could incorporate an identity development component into college health programming.

The Questionnaire for Eudaimonic Well-Being: Psychometric properties, demographic comparisons, and evidence of validity

The Questionnaire for Eudaimonic Well-Being (QEWB) was developed to measure well-being in a manner consistent with how it is conceptualized in eudaimonist philosophy. Aspects of eudaimonic well-being assessed by the QEWB include self-discovery, perceived development of one's best potentials, a sense of purpose and meaning in life, intense involvement in activities, investment of significant effort, and enjoyment of activities as personally expressive. The QEWB was administered to two large, ethnically diverse samples of college students drawn from multiple sites across the United States. A three-part evaluation of the instrument was conducted: (1) evaluating psychometric properties, (2) comparing QEWB scores across gender, age, ethnicity, family income, and family structure, and (3) assessing the convergent, discriminant, construct, and incremental validity of the QEWB. Six hypotheses relating QEWB scores to identity formation, personality traits, and positive and negative psychological functioning were evaluated. The internal consistency of the scale was high and results of independent CFAs indicated that the QEWB items patterned onto a common factor. The distribution of scores approximated a normal curve. Demographic variables were found to predict only small proportions of QEWB score variability. Support for the hypotheses tested provides evidence for the validity of the QEWB as an instrument for assessing eudaimonic well-being. Implications for theory and future research directions are discussed.

Perceived Parental Relationships and Health-Risk Behaviors in College-Attending Emerging Adults

The present study investigated the association of perceived parenting with health-risk behaviors in an ethnically diverse sample of 1,728 college-attending emerging adults. Participants completed retrospective measures of perceived maternal and paternal nurturance, connection, psychological control, and disrespect and reported their frequency of binge drinking, illicit drug use, unsafe sexual behavior, and impaired driving. Multivariate Poisson regression analyses indicated that perceived paternal acceptance was associated inversely with 6 of the 12 health-risk behaviors measured, whereas perceived mothering was related only to 2 of these health-risk behaviors. These patterns were consistent across gender, ethnicity, and family structure.

Toward promoting generative cultures of intentional mentoring within academic settings

Mentoring promotes ongoing learning of clinical psychologists, regardless of their expertise and experience. Most academic programs, however, do not possess vigorous mentoring cultures in which mentors simultaneously are learners. Academic programs are largely based on "mastery" philosophies that tacitly aim mentoring at less-experienced peers. This orientation can make stigmatizing mentoring opportunities, especially for psychologists from underrepresented populations. Using concepts from experiential learning theory, we articulate interventions to invigorate mentoring cultures and make mentoring less stigmatizing.

Experience of maltreatment as a child and acceptance of violence in adult intimate relationships: mediating effects of distortions in cognitive schemas

Links exist between being subjected to maltreatment as a child and tendencies to accept violence as normative in adult relationships. Constructivist Self Development Theory suggests that such relationships may be affected by "cognitive disruptions" in "self" and "other" schemas. Mediating effects of distorted cognitive schemas on the association between history of child maltreatment and the acceptance of violence in intimate interpersonal relationships were investigated among 433 men and women. Outcomes indicated that individuals who reported childhood maltreatment were more likely to display distortions in their cognitive schemas and those individuals with disrupted schemas were more likely to accept relationship violence. Least-square multiple regression analyses revealed that distorted beliefs fully mediated the relationship between reporting childhood maltreatment and acceptance of violence, for both men and women. Subsidiary analyses suggested that this full mediation was replicated for schemas involving the self but not for schemas about others.

The influence of a hexametaphosphate-containing chewing gum on the wetting ability of salivary conditioning films in vitro and in vivo

OBJECTIVE

Adsorbed conditioning films of salivary components on dental enamel surfaces or pellicles form the interface between teeth and the oral environment. The wetting ability of salivary conditioning films dictates biological adhesion phenomena such as plaque formation, calcification and staining, and also influences mouth perception through effects on lubricity. This study assessed the effects of hexametaphosphate release from a chewing gum matrix on the wetting ability of salivary conditioning films in vitro and in vivo.

METHODOLOGY

Results obtained for hexametaphosphate chewing gum were compared with those produced by hexametaphosphate-containing dentifrice, which has been clinically proven to have efficacy for stain removal and prevention and dental calculus prevention.

RESULTS

Contact angle assessments revealed that hexametaphosphate dentifrice produced markedly hydrophilic conditioning films in vitro. Hexametaphosphate chewing gums had only minor effects on surface contact angles in vitro. However, in vivo intra-oral contact angle measurements on tooth surfaces in volunteers showed that both hexametaphosphate dentifrice and chewing gum produced more hydrophilic tooth surfaces.

CONCLUSION

These results support the activity of hexametaphosphate on tooth surfaces delivered both from dentifrice and chewing gum forms.

Domain bridging interactions. A necessary contribution to the function and structure of Escherichia coli aspartate transcarbamoylase

Aspartate transcarbamoylase undergoes a domain closure in the catalytic chains upon binding of the substrates that initiates the allosteric transition. Interdomain bridging interactions between Glu(50) and both Arg(167) and Arg(234) have been shown to be critical for stabilization of the R state. A hybrid version of the enzyme has been generated in vitro containing one wild-type catalytic subunit, one catalytic subunit in which Glu(50) in each catalytic chain has been replaced by Ala (E50A), and wild-type regulatory subunits. Thus, the hybrid enzyme has one catalytic subunit capable of domain closure and one catalytic subunit incapable of domain closure. The hybrid does not behave as a simple mixture of the constituent subunits; it exhibits lower catalytic activity and higher aspartate affinity than would be expected. As opposed to the wild-type enzyme, the hybrid is inhibited allosterically by CTP at saturating substrate concentrations. As opposed to the E50A holoenzyme, the hybrid is not allosterically activated by ATP at saturating substrate concentrations. Small angle x-ray scattering showed that three of the six interdomain bridging interactions in the hybrid is sufficient to cause the global structural change to the R state, establishing the critical nature of these interactions for the allosteric transition of aspartate transcarbamoylase.

Influence of 3-methylcholanthrene pretreatment on sanguinarine toxicity in mice

We examined the effect of 3-methylcholanthrene (3-MC) on the liver toxicity of sanguinarine in mice. Administration of 10 mg sanguinarine/kg bw ip to male mice resulted in significant decreases in liver glutathione and P450 enzymes activities, and increased in sorbitol dehydrogenase and alanine aminotransferase levels in serum suggestive of liver damage. However, pretreatment with 20 mg 3-MC/kg/d ip, an inducer of P450 enzymes, for 3 d mitigated the sanguinarine toxic effects suggesting 3-MC induced cytochrome P450 enzymes that promote detoxification of sanguinarine.

Characterization of the aspartate transcarbamoylase from Methanococcus jannaschii

The genes from the thermophilic archaeabacterium Methanococcus jannaschii that code for the putative catalytic and regulatory chains of aspartate transcarbamoylase were expressed at high levels in Escherichia coli. Only the M. jannaschii PyrB (Mj-PyrB) gene product exhibited catalytic activity. A purification protocol was devised for the Mj-PyrB and M. jannaschii PyrI (Mj-PyrI) gene products. Molecular weight measurements of the Mj-PyrB and Mj-PyrI gene products revealed that the Mj-PyrB gene product is a trimer and the Mj-PyrI gene product is a dimer. Preliminary characterization of the aspartate transcarbamoylase from M. jannaschii cell-free extract revealed that the enzyme has a similar molecular weight to that of the E. coli holoenzyme. Kinetic analysis of the M. jannaschii aspartate transcarbamoylase from the cell-free extract indicates that the enzyme exhibited limited homotropic cooperativity and little if any regulatory properties. The purified Mj-catalytic trimer exhibited hyperbolic kinetics, with an activation energy similar to that observed for the E. coli catalytic trimer. Homology models of the Mj-PyrB and Mj-PyrI gene products were constructed based on the three-dimensional structures of the homologous E. coli proteins. The residues known to be critical for catalysis, regulation, and formation of the quaternary structure from the well characterized E. coli aspartate transcarbamoylase were compared.

Making consignment- and vendor-managed inventory work for you

This article will examine some of the benefits of vendor managed inventory (VMI) and consignment from a supplier's perspective. Indeed, there are benefits to both approaches, as well as costs and risks. By understanding and managing the costs, and controlling the risks through careful negotiations, one can make both consignment and VMI work not only for the customer, but for the supplier as well.

Break through to success with training and teamwork

This is a case study on the effect of training and teamwork in two different divisions within the same company. One division consisted of a nonunion manufacturing plant; the second was a unionized distribution operation. In both operations, serious problems existed--poor customer service levels, inadequate inventory turns, and insufficient profitability. These are the kinds of problems that, left untreated, can cause the death of any manufacturing or distribution operation. However, by implementing training and teamwork at both operations, impressive benefits were achieved, including customer service levels exceeding 90 percent, dramatic improvements in the inventory turnover rate, and profitability that exceeded corporate goals.

Threonine 82 in the regulatory chain is important for nucleotide affinity and for the allosteric stabilization of Escherichia coli aspartate transcarbamoylase

The three-dimensional structure of Escherichia coli aspartate transcarbamoylase complexed with the allosteric effector CTP, shows an interaction between the hydroxyl of Thr-82 in the regulatory chain (Thr-82r) with the gamma-phosphate of CTP (R.P. Kosman, J.E. Gouaux, W.N. Lipscomb, Crystal structure of CTP-ligated T state aspartate transcarbamoylase at 2.5 A resolution: implications for aspartate transcarbamoylase mutants and the mechanism of negative cooperativity, Proteins Struct. Funct. Genet. 15 (1993) 147-176). In order to determine whether the Thr-82r interaction with the gamma-phosphate of CTP is important for either binding of the nucleotide effectors or their function, site-specific mutagenesis was employed. The mutant enzyme in which Thr-82r was replaced by Ala had almost the identical maximal observed specific activity as the wild-type enzyme; however, the mutant enzyme had a significantly increased [Asp]0.5, the aspartate concentration at one-half the maximal observed specific activity, as well as slightly increased homotropic cooperativity. The mutant enzyme was also activated more by ATP and inhibited less by CTP as compared to the wild-type enzyme. In addition, the nucleotide concentration required for one-half maximal effect was increased approx. 3-fold as compared to the corresponding values for the wild-type enzyme. The maximal inhibition of the mutant enzyme, in the presence of UTP and CTP was similar to that observed for the wild-type enzyme; however, higher concentrations of the nucleotides were required to achieve this level of inhibition. The reduced affinity of CTP, UTP and ATP induced by the mutation indicates that the hydrogen bonding interaction between the gamma-phosphate of the nucleotide effector and the side-chain hydroxyl of Thr-82r is important for the binding of the nucleotide effectors to the allosteric site. Furthermore, this interaction is important for the discrimination between CTP and CDP. Finally, the greater homotropic cooperativity, greater [Asp]0.5, diminished CTP inhibition and greater ATP activation of the mutant enzyme correlates with the X-ray structure of the mutant enzyme which shows that the unligated enzyme is in an 'extreme' T-state. These findings add support to the theory that the global stabilization of the enzyme is critical for both the homotropic and heterotropic properties of aspartate transcarbamoylase.

A single mutation in the regulatory chain of Escherichia coli aspartate transcarbamoylase results in an extreme T-state structure

Kinetic analysis of a mutant version of Escherichia coli aspartate transcarbamoylase in which Thr82 in the regulatory chain (Thr82r) was replaced by Ala results in a shift in the T <==> R equilibrium towards the T-state. In order to understand the structural determinants of this T-state stabilization, the X-ray structure of the unliganded Thr82r-->Ala enzyme was determined at 2. 6 A resolution and refined to a crystallographic residual of 0.175. The structure of the mutant r1 regulatory chain is more similar to that of the r6 regulatory chain than observed for the wild-type enzyme, resulting in a more symmetric structure. Furthermore, the structural changes in the mutant enzyme appears to occur only in the r1 chain, while the r6 chain is almost identical in structure to that of the r6 chain of the wild-type enzyme. The structure of the mutant enzyme exhibits alterations in the subunit interfaces between the regulatory and catalytic chains, as well as in the interface between the allosteric and zinc domains within the regulatory chain. Moreover, the regulatory dimers are rotated around their respective 2-fold axes approximately 1 degrees beyond the rotation which occurs in the wild-type T-state enzyme. The structural analysis indicates that the enzyme is an "extreme" T-state, in which a larger rotation of the regulatory dimers is required for the T to R transition compared to the wild-type enzyme. This extreme T-state structure correlates well with the kinetic parameters determined for the mutant enzyme, showing a stabilized T-state. Furthermore, the structural analysis of the mutant enzyme suggests that replacement of Thr82r with Ala alters the local conformation of the nucleotide binding pocket and therefore offers a plausible explanation for the reduced affinity of the enzyme for nucleotides.

Development of revised Ionising Radiations Regulations

New standards in ICRP60 led to the revision of the 1980 European Basic Safety Standards Directive, which in turn has created the necessity to revise the Ionising Radiations Regulations 1985. Proposals from the Health and Safety Commission (HSC) for revised regulations are currently out for public consultation in a formal Consultative Document. This article describes some of the background to the proposals in the Consultative Document, key influences on the revision process and the methods used to develop the proposal so that they are broadly acceptable to stakeholders. Some of the changes proposed are structural in nature, such as integration of the provision of the Outside Workers Regulations. Others are of a legal nature and include: new proposals for justification, prior authorisation and risk assessment; two options for the dose limitation system; and significant changes to the means of recognising the competence of the Radiation Protection Adviser. Following the current public consultation, final proposals need to be drawn up, approved by HSC and cleared through the European Commission under procedures required by the Euratom Treaty. If all goes according to plan, the revised regulations should be on the Statute Book about the middle of next year, with most provisions coming into force on 1 January 2000.

Self-esteem, gender, and alcohol use: relationships with HIV risk perception and behaviors in college students

The present study examined the confluence of alcohol use and self-esteem on risky sexual behavior and perceptions of risk for female and male college students. It was predicted that higher levels of self-esteem, female gender, and lower alcohol consumption would be associated with greater condom use and lower perceptions of risk for self and partner. Results indicated that for low drinking students, those with high self-esteem reported greater condom use. In addition, low rates of alcohol use were associated with greater frequency of past condom use. Women and students low in self-esteem indicated greater perceptions of risk for themselves and their partners. These findings are discussed in terms of their implications for developing interventions aimed at reducing risky sexual behavior.

From zero to teamwork: a manufacturing journey

This article is a case study of the implementation of employee-empowered problem-solving teams. Topics include how projects were selected, how project teams were trained, and how obstacles were overcome. Ths article concludes with 10 recommendations for organizations that would like to initiate team-based activities.

Fructose-1,6-bisphosphatase: arginine-22 is involved in stabilization of the T allosteric state

A comparison of the X-ray crystallographic structures of the R and T allosteric states [Ke, H. M., Liang, J.-Y., Zhang, Y., & Lipscomb, W. N. (1991) Biochemistry 30, 4412-4420] of the pig kidney fructose-1,6-bisphosphatase (EC 3.1.3.11) reveals major changes in the quaternary structure of the enzyme upon the binding of the allosteric inhibitor AMP. This change in quaternary structure involves the breaking of one set of interactions that stabilize the R state and the formation of another set of interactions that stabilize the T state of the enzyme. In particular, the interactions of Arg-22 with nearby amino acid residues are quite different in the R and T states of the enzyme. Although the crystallographic data suggest that intersubunit interactions such as those involving Arg-22 are important for stabilization of the R and/or T states, the X-ray structures do not provide direct evidence concerning the functional role of specific amino acid residues. Therefore, site-specific mutagenesis has been used to probe the function of Arg-22 in pig kidney fructose-1,6-bisphosphatase. The replacement of Arg-22 by Ala results in a mutant enzyme with enhanced catalytic efficiency compared to the wild-type, as indicated by a kinetic analysis showing a slightly lower Km and increased Vmax compared to the wild-type enzyme. In addition, the substitution enhances both substrate inhibition and the affinity of the inhibitor fructose 2,6-bisphosphate. Moreover, the replacement of Arg-22 by Ala results in a more than 10-fold loss of the ability of AMP to inhibit the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Overexpression and purification of the trimeric aspartate transcarbamoylase from Bacillus subtilis

A procedure has been developed for the overexpression and purification of milligram quantities of the Bacillus subtilis aspartate transcarbamoylase. The plasmid pEK171, carrying the B. subtilis pyrB structural gene under the control of the Escherichia coli pyrBI promoter, was transformed into the E. coli strain EK1104 and the enzyme overexpressed to approximately 50% of total soluble protein under extreme derepression of the pyrimidine pathway. The enzyme was subsequently purified by means of ammonium sulfate fractionation, anionic exchange chromatography using Q-Sepharose Fast Flow resin, negative chromatography on Matrex Gel Red A agarose, and hydrophobic interaction chromatography using Matrex Phenyl Cellufine. The purification yields approximately 60 mg of pure enzyme per liter of bacterial culture. Kinetic analysis of the overexpressed enzyme indicated that it had kinetic properties very similar to those of the enzyme purified from B. subtilis cells.

Shared active sites of fructose-1,6-bisphosphatase. Arginine 243 mediates substrate binding and fructose 2,6-bisphosphate inhibition

The active site of pig kidney fructose-1,6-bisphosphatase (EC 3.1.3.11) is shared between subunits, Arg-243 of one chain interacting with fructose-1,6-bisphosphate or fructose-2,6-bisphosphate in the active site of an adjacent chain. In this study, Arg-243 was replaced by alanine using techniques of site-specific mutagenesis and the cloned pig kidney enzyme expressed in Escherichia coli. Compared with wild-type enzyme, kinetic parameters of the altered enzyme characterizing catalytic efficiency, magnesium binding, and inhibition by AMP differed but by less than an order of magnitude; affinity for substrate fructose 1,6-bisphosphate was 10-fold poorer, and affinity for inhibitor fructose 2,6-bisphosphate was 1000-fold poorer. Molecular dynamics simulations were undertaken to determine possible alterations in active sites of the enzyme due to replacement of Arg-243 by Ala and suggested that in the mutant enzyme loss of one cationic group leads to reorganization of the active site especially involving lysine residues 269 and 274. The differences in properties of the mutant enzyme indicate the key importance of Arg-243 in the function of fructose-1,6-bisphosphatase and confirm on a functional basis the shared active site in this important metabolic enzyme.

Alfalfa yield response to inoculation with recombinant strains of Rhizobium meliloti with an extra copy of dctABD and/or modified nifA expression

The construction of rhizobial strains which increase plant biomass under controlled conditions has been previously reported. However, there is no evidence that these newly constructed strains increase legume yield under agricultural conditions. This work tested the hypothesis that carefully manipulating expression of additional copies of nifA and dctABD in strains of Rhizobium meliloti would increase alfalfa yield in the field. The rationale for this hypothesis is based on the positive regulatory role that nifA plays in the expression of the nif regulon and the fact that a supply of dicarboxylic acids from the plant is required as a carbon and energy source for nitrogen fixation by the Rhizobium bacteroids in the nodule. These recombinant strains, as well as the wild-type strains from which they were derived, are ideal tools to examine the effects of modifying or increasing the expression of these genes on alfalfa biomass. The experimental design comprised seven recombinant strains, two wild-type strains, and an uninoculated control. Each treatment was replicated eight times and was conducted at four field sites in Wisconsin. Recombinant strain RMBPC-2, which has an additional copy of both nifA and dctABD, increased alfalfa biomass by 12.9% compared with the yield with the wild-type strain RMBPC and 17.9% over that in the uninoculated control plot at the site where soil nitrogen and organic matter content was lowest. These increases were statistically significant at the 5% confidence interval for each of the three harvests made during the growing season. Strain RMBPC-2 did increase alfalfa biomass at the Hancock site; however, no other significant increases or decreases in alfalfa biomass were observed with the seven other recombinant strains at that site. At three sites where this experiment was conducted, either native rhizobial populations or soil nitrogen concentrations were high. At these sites, none of the recombinant strains affected yield. We conclude that RMBPC -2 can increase alfalfa yields under field conditions of nitrogen limitation, low endogenous rhizobial competitors, and sufficient moisture.

Allan-Herndon-Dudley syndrome: clinical and linkage studies on a second family

We restudied a family with X-linked mental retardation (XLMR) originally reported in abstract form by Davis et al. [1981]. All 8 living affected males were examined. Characteristics included severe mental retardation, spastic paraplegia, dysarthria, muscle wasting, scoliosis, broad shallow pectus excavatum, long face, large ears with minor modeling anomalies, foot deformities, joint contractures, and neck drop. Stature, OFC, testicular volume, high resolution chromosome and fragile X studies, and plasma amino acids were all normal. Their manifestations closely resemble those of a large family with XLMR originally reported by Allan et al. [1944] and restudied by Stevenson et al. [1990]. This condition has been termed the Allan-Herndon-Dudley syndrome (AHDS). As AHDS has been mapped to Xq21, mapping studies were undertaken to determine if this family maps to the same location. These studies demonstrate tight linkage to Xq21, with a maximum lod score of 2.88 obtained with probe pX65H7 (DXS72). Multipoint analysis located the mutant gene quite close to pX65H7 (multipoint Z = 4.14), slightly more proximal in Xq21 than was suggested by the data from the original AHDS family. It appears likely that this family is the second reported family with AHDS.

Isolation and sequence analysis of the cDNA for pig kidney fructose 1,6-bisphosphatase

A full-length clone of pig kidney fructose 1,6-bisphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) was isolated by screening a cDNA library for complementation of an Escherichia coli fbp deletion mutation. The open reading frame of 1011 bases corresponds to 337 amino acids, two more than have been previously reported [Marcus, F., Edelstein, I., Reardon, I. & Heinrikson, R. L. (1982) Proc. Natl. Acad. Sci. USA 79, 7161-7165]. The extra two amino acids (Ala-Lys) are located at the C-terminal end of the protein as an extension. Comparison of the deduced amino acid sequence with the reported (see above) and revised amino acid sequence [Harrsch, P. B., Kim, Y., Fox, J. L. & Marcus, F. (1985) Biochem. Biophys. Res. Commun. 133, 520-526] indicates three differences in addition to the C-terminal extension. Gln-20, Thr-96, and Asn-199 in the amino acid sequence are found to be Glu, Ser, and Asp, respectively. Since the x-ray structure of the pig kidney enzyme has been reported, the cDNA clone will allow the construction of site-specific mutants to help test possible structure-function relationships in this important metabolic enzyme.

Intrauterine cytomegalovirus infection presenting as fetal meconium peritonitis

Recent reports have suggested that focal hyperechoic abdominal masses detected during the second trimester may represent a normal variation in fetal intestinal development that is transient in nature and not associated with pathologic conditions. The patient described here had second-trimester ultrasonic findings of fetal meconium peritonitis without ascites, polyhydramnios, or other anomalies. Subsequent ultrasound examinations at 22, 30, and 36 weeks demonstrated no change in the abdominal appearance. At birth, this preterm male infant had clinical symptoms of congenital cytomegalovirus infection confirmed by viral culture and serologic studies. Retrospective studies of maternal serum obtained early in the second trimester confirmed a primary cytomegalovirus infection 4 weeks before the initial ultrasound examination. Although fetal hydrops and ascites have occasionally been associated with intrauterine cytomegalovirus infection, fetal meconium peritonitis has not been previously recognized in patients with congenital cytomegalovirus.

Expression and functional analysis of the Rhizobium meliloti nif A gene

The translational initiation point for Rhizobium meliloti nifA, the specific activator for nitrogen fixation (nif) genes, was determined. When expressed in an Escherichia coli linked transcriptional-translational system the DNA coding for the R.meliloti nifA gene produced four polypeptide bands of 71 000, 67 000, 62 000 and 59 000 daltons. There are three in-frame ATG codons at the N-terminus of the gene; by replacing the poor ribosome binding sites of the native DNA with a synthetic consensus ribosome binding site prior to each of ATG codons the polypeptides were produced at enhanced levels and related to each of the initiation codons. The ability of these specifically expressed polypeptides to activate nif promoters fused to lacZ was determined. Only the fulllength polypeptide activated the Klebsiella pneumoniae nifH, R.meliloti nifH and fixA and Bradyrhizobium japonicum nifH and nifD promoters. The R.meliloti fixA promoter, contrary to previous evidence, could be activated in E.coli. Deletion of the putative N-terminal domain of the R.meliloti nifA gene product greatly increased the ability of the protein to activate nif promoters. However, deletions retaining part of this domain were not functional. This shows that the N-terminal domain is not essential for activity and that its presence decreases the full potential function of the protein. Our results are consistent with the suggesting that this domain has a regulatory role. In contrast to K.pneumoniae nifA protein, the function of the full length and domain deleted forms of R.meliloti nifA gene product was sensitive to oxygen in E.coli.

Thiram-induced toxic liver injury in male Sprague-Dawley rats

A single i.p. dose (120 mg/kg) of thiram given to male Sprague-Dawley rats caused a significant increase in the activity of SGOT and SGPT 24 hr post-treatment indicating liver damage. A considerable diminution in the serum cholinesterase activity was also noted in the treated rats as against the control animals. Additional evidence for thiram-induced liver toxicity is provided by the observation that there was approximately 50% inhibition of the activity of hepatic microsomal benzphetamine N-demethylase with a concomitant decrease in the concentration of cytochrome P-450, an important component of the mixed-function oxidase system. Although not significant, hepatic glutathione levels were also depleted by thiram, probably making the liver susceptible to toxic injury.

Biological tests of lead absorption following a brief massive exposure

A contractor's man suffered a brief, massive exposure to lead fume by contaminating and then smoking hand-rolled cigarettes. His blood lead concentration rose very rapidly to very high levels, but zinc erythrocyte protoporphyrin, urinary lead, and urinary coproporphyrin did not. It is possible that only the blood lead concentration is of value in detecting brief massive exposure.

Blood lead and the symptoms of lead absorption

ABSTRACT Eighty-one percent of all hourly paid men who had been employed for more than six months in a factory making lead acid batteries and plastics completed a modified Cornell medical index health questionnaire. Blood lead and erythrocyte protoporphyrin (EPP) were also measured. The questions were grouped into symptom categories as follows: all physical, all psychological, “potentially lead induced,” pulmonary, cardiovascular, gastrointestinal, skin, nervous system, genitourinary, and fatigue. For each symptom category the pooled percentages of men whose symptom scores were above the common median of the three blood lead groups 10-, 40-, and 60 and over μg/100 ml (0·48-, 1·93-, and 2·90 and over μmol/l) within age/smoking subgroups were calculated. In every symptom category the percentages in the two lower blood lead groups differed little, but the percentages were consistently higher in men with blood concentration of 60 μg/100 ml (2·90 μmol/l) and over. Differences between a combined 10-59 μg/100 ml (0·48-2·85 μmol/l) blood lead group and the 60 and over μg/100 ml (≥2·90 μmol/l) group were statistically significant at the 0·01 level for “potentially lead induced” symptoms and at the 0·05 level for skin and psychological symptoms. Broadly similar results were obtained with four log₁₀ EPP groups 0·6-, 1·5-, 1·7-, and ≥2·0, but differences did not reach statistical significance. There was no obvious explanation as to why symptoms that are not found in classic lead poisoning should be increased almost as much as those that are. It was thought that these results could be biased due to the men's knowledge of the symptoms associated with lead exposure, but the possibility that they may be partly due to lead absorption cannot be excluded.