A Gene-Acculturation Study of Obesity Among US Hispanic/Latinos: The Hispanic Community Health Study/Study of Latinos

OBJECTIVE

In the United States, Hispanic/Latino adults face a high burden of obesity; yet, not all individuals are equally affected, partly due in part to this ethnic group's marked sociocultural diversity. We sought to analyze the modification of body mass index (BMI) genetic effects in Hispanic/Latino adults by their level of acculturation, a complex biosocial phenomenon that remains understudied.

METHODS

Among 11,747 Hispanic/Latinos adults in the Hispanic Community Health Study/Study of Latinos aged 18 to 76 years from four urban communities (2008-2011), we a) tested our hypothesis that the effect of a genetic risk score (GRS) for increased BMI may be exacerbated by higher levels of acculturation and b) examined if GRS acculturation interactions varied by gender or Hispanic/Latino background group. All genetic modeling controlled for relatedness, age, gender, principal components of ancestry, center, and complex study design within a generalized estimated equation framework.

RESULTS

We observed a GRS increase of 0.34 kg/m 2 per risk allele in weighted mean BMI. The estimated main effect of GRS on BMI varied both across acculturation level and across gender. The difference between high and low acculturation ranged from 0.03 to 0.23 kg/m 2 per risk allele, but varied across acculturation measure and gender.

CONCLUSIONS

These results suggest the presence of effect modification by acculturation, with stronger effects on BMI among highly acculturated individuals and female immigrants. Future studies of obesity in the Hispanic/Latino community should account for sociocultural environments and consider their intersection with gender to better target obesity interventions.

Poor clinical guideline adherence and inappropriate testing for incident lower urinary tract symptoms associated with benign prostatic hyperplasia

BACKGROUND

The American Urological Association makes recommendations for evaluation and testing for lower urinary tract symptoms associated with benign prostatic hyperplasia (LUTS/BPH) to help primary care providers and specialists identify LUTS/BPH and harmful related conditions including urinary retention and prostate or bladder cancer. Our understanding of provider adherence to these Guidelines is limited to single-site or nonrepresentative settings.

METHODS

We analyzed two insurance claims databases: the Optum^® de-identified Clinformatics^® Data Mart database for privately insured males aged 40-64 years (N ≈ 1,650,900 annually) and the Medicare 5% Sample for males aged ≥65 years (N ≈ 546,000 annually). We calculated the annual prevalence of LUTS/BPH and comorbid bladder cancer and bladder stones from 2004 to 2013. We additionally examined LUTS/BPH incidence and adherence to testing guidelines in a cohort of men newly diagnosed with LUTS/BPH in 2009.

RESULTS

While LUTS/BPH prevalence and incidence increased with increasing age, evaluation testing became less common. Urinalysis was the most common testing type but was performed in <60% of incident patients. Serum prostate-specific antigen (PSA) was the second most common test across age groups (range: 15-34%). Prevalence of comorbid bladder cancer (range: 0-4%), but not bladder stones (range: 1-2%), increased with increasing age.

CONCLUSIONS

Although older men were at greater risk of LUTS/BPH than younger men, they were less likely to undergo testing at diagnosis. Recommended testing with urinalysis was poor despite higher prevalence of bladder cancer in older men and a standard recommendation for urinalysis since 1994. Providers should be more cognizant of AUA Guidelines when assessing LUTS/BPH patients.

Intergenerational educational mobility and type 2 diabetes in the Sacramento Area Latino Study on Aging

PURPOSE

United States (US) Latinos have the lowest educational attainment of any US racial/ethnic group, which may contribute to their disparate burden of Type 2 Diabetes. Herein, we aimed to examine the association between intergenerational educational mobility and Type 2 Diabetes among US Latino adults.

METHODS

We used data from the Niños Lifestyle and Diabetes Study (2013-2014) and the Sacramento Area Latino Study on Aging (1998-1999) to link 616 adult Latino children to their parents. Model-based standardization and robust Poisson regression were used to estimate the prevalence of prediabetes, Type 2 Diabetes, treatment and glycemic control, and describe their associations with intergenerational educational mobility.

RESULTS

Adult children with stable high intergenerational educational attainment had a higher prevalence of prediabetes (Prevalence Ratio, PR=1.58; 95% Confidence Interval, CI=1.08, 2.34) and lower prevalence of Type 2 Diabetes (PR=0.64, CI=0.41, 0.99), as compared to those who experienced low educational attainment across generations. Downward mobility was associated with a higher prevalence of prediabetes (PR=1.54, CI=1.06, 2.23) and worse glycemic control (PR=2.20, CI=1.13, 4.30), and upward mobility was associated with a lower prevalence of Type 2 Diabetes (PR=0.39, CI=0.22, 0.70).

CONCLUSIONS

Our findings from a predominantly Mexican-heritage community suggest that higher education across generations may buffer individuals from glycemic dysregulation. As such, higher education may be a promising public health target to address the rising burden of Type 2 Diabetes in the US.

A prospective study of multiple sleep dimensions and hypertension risk among white, black and Hispanic/Latina women: findings from the Sister Study

BACKGROUND

Poor sleep is associated with increased hypertension risk, but few studies have evaluated multiple sleep dimensions or investigated racial/ethnic disparities in this association among women.

METHOD

We investigated multiple sleep dimensions (sleep duration, inconsistent weekly sleep patterns, sleep debt, frequent napping and difficulty falling or staying asleep) and hypertension risk among women, and determined modification by age, race/ethnicity and menopausal status. We used data from the Sister Study, a national cohort of 50 884 women who had sisters diagnosed with breast cancer in the United States enrolled in 2003-2009 and followed through September 2018.

RESULTS

Of 33 497 women without diagnosed hypertension at baseline (mean age ± standard deviation: 53.9 ± 8.8 years; 88.7% White, 6.4% Black and 4.9% Hispanic/Latina), 23% (n = 7686) developed hypertension over a median follow-up of 10.1 years [interquartile range: 8.2-11.9 years]. Very short, short or long sleep duration, inconsistent weekly sleep patterns, sleep debt, frequent napping, insomnia, insomnia symptoms as well as short sleep and exploratory cumulative poor sleep score were associated with incident hypertension after adjustment for demographics factors. After additional adjustment for lifestyle and clinical factors, insomnia [hazard ratio = 1.09, 95% confidence interval (95% CI): 1.03-1.15] and insomnia symptoms plus short sleep (hazard ratio = 1.13, 95% CI: 1.05-1.21) remained associated with incident hypertension. These associations were stronger in younger (age<54 vs. ≥54 years) and premenopausal vs. postmenopausal women (all P-interaction < 0.05). Associations did not differ by race/ethnicity (all P-interaction > 0.05).

CONCLUSION

Thus, screening for multiple sleep dimensions and prioritizing younger and premenopausal women may help identify individuals at high risk for hypertension.

Concordance between self-reported and actigraphy-assessed sleep duration among African-American adults: findings from the Jackson Heart Sleep Study

STUDY OBJECTIVES

Most epidemiological studies assess sleep duration using questionnaires. Interpreting this information requires understanding the extent to which self-reported habitual sleep reflects objectively assessed sleep duration, particularly among African Americans, who disproportionately experience poor sleep health.

METHODS

Among African-American participants of the Jackson Heart Sleep Study, we investigated differences in questionnaire-based self-assessed average sleep duration and self-assessed wake-bed time differences compared to actigraphy-based assessments of total sleep time (TST) and average time in bed (TIB). Linear regression models provided estimates of concordance between actigraphy-based and self-reported sleep duration.

RESULTS

Among 821 adults, self-assessed average sleep duration was lower than self-assessed wake-bed time differences (6.4 ± 1.4 vs. 7.5 ± 1.7 h, p < 0.0001). Mean actigraphy-based TST was 6.6 ± 1.2 h, and actigraphy-based average TIB was 7.6 ± 1.2 h. Self-assessed average sleep duration and actigraphy-based TST were moderately correlated (r = 0.28, p < 0.0001). Self-assessed average sleep duration underestimated actigraphy-based TST by -30.7 min (95% confidence intervals [CI]: -36.5 to -24.9). In contrast, self-assessed wake-bed time differences overestimated actigraphy-based TST by 45.1 min (95% CI: 38.6-51.5). In subgroup analyses, self-assessed average sleep duration underestimated actigraphy-based measures most strongly among participants with insomnia symptoms.

CONCLUSIONS

Among African Americans, self-assessed average sleep duration underestimated objectively measured sleep while self-assessed wake-bed time differences overestimated objectively measured sleep. Sleep measurement property differences should be considered when investigating disparities in sleep and evaluating their associations with health outcomes.

National Trends in Neuromodulation for Urinary Incontinence Among Insured Adult Women and Men, 2004-2013: The Urologic Diseases in America Project

OBJECTIVE

To examine US trends in neuromodulation for urinary incontinence (UI) treatment from 2004 to 2013.

METHODS

This study utilized 2 data sources: the Optum© de-identified Clinformatics® Data Mart Database for privately insured adults aged 18-64 years with a UI diagnosis (N≈40,000 women and men annually) and the Medicare 5% Sample for beneficiaries aged ≥65 years with a UI diagnosis (N≈65,000 women and men annually). We created annual cross-sectional cohorts and assessed prevalence of UI-related neuromodulation procedures among men and women separately from 2004 to 2013. Analyses were conducted overall and stratified by age, race/ethnicity, and geographic region.

RESULTS

Nearly all neuromodulation procedures occurred in outpatient settings. Sacral neuromodulation (SNM) procedures for UI in both women and men grew steadily from 2004 to 2013, with more procedures performed in women than men. Among women with UI, SNM prevalence grew from 0.1%-0.2% in 2004 to 0.5%-0.6% in 2013. Posterior tibial nerve stimulation (PTNS) experienced growth from 2011 to 2013. Chemodenervation of the bladder with onabotulinumtoxinA (BTX) combined with other injectable procedures (including urethral bulking) remained stable over time.

CONCLUSIONS

From 2004 to 2013, SNM procedures remained relatively uncommon but increased consistently. PTNS experienced growth starting in 2011 when PTNS-specific insurance claims became available. BTX trends remain unclear; future studies should assess it separately from other injectable procedures. Neuromodulation has a growing role in UI treatment, and ongoing trends will be important to examine.

1016 Multiple Sleep Disturbances and Hypertension Risk Among White, Black, and Hispanic/Latina Women

Introduction

Poor sleep has been associated with a higher risk of hypertension, but few prospective studies have included multiple sleep dimensions and few have investigated age differences or racial/ethnic disparities in this relationship among pre- and post-menopausal women.

Methods

To investigate the association between sleep disturbances and hypertension risk, we used data from women in the United States enrolled in the Sister Study who were aged 35 to 74 years at baseline (2003 to 2009) and did not have hypertension at enrollment. Participants were followed through September 2017. Sleep duration, inconsistent weekly sleep patterns, sleep debt, frequent napping, and insomnia symptoms were reported at baseline. During follow-up, participants reported whether they were diagnosed by a healthcare provider with hypertension. Adjusting for sociodemographic characteristics, health behaviors, and health conditions including diabetes and depression, we used Cox Proportional Hazards regression to estimate hypertension risk among women with vs. without unfavorable sleep characteristics. We also investigated potential modification by race/ethnicity, age,and menopausal status.

Results

Of 33,175 women without hypertension at baseline (mean age ± standard deviation: 53.9 ±8.8 years; 88.8% White, 6.4% Black, and 4.9% Hispanic/Latina), 19.9% developed hypertension over a median follow-up of 9.2 years (interquartile range: 7.6 to 10.9). After adjustment, insomnia symptoms (hazard ratio[HR]=1.08 (95% Confidence Interval [CI]: 1.03-1.15)) and insomnia symptoms combined with short sleep (HR=1.14 (95% CI: 1.06-1.23)) were associated with incident hypertension. While similar across race/ethnicity, these associations were stronger in younger (age &lt;54 vs. ≥54 years) and premenopausal vs. postmenopausal women (p-values for interaction &lt;0.05).

Conclusion

Sleep disturbances related to insomnia were associated with an increased risk of hypertension, especially among younger and premenopausal women.

Support

This work was funded by the Intramural Program at the National Institutes of Health (NIH), National Institute of Environmental Health Sciences (NIEHS, Z1AES103325-01 [CLJ] and Z01 ES044005 [DPS]).

Concomitant Use of Gabapentinoids with Opioids Is Associated with Increased Mortality and Morbidity among Dialysis Patients

BACKGROUND

The opioid epidemic is a public health emergency and appropriate medication prescription for pain remains challenging. Physicians have increasingly prescribed gabapentinoids for pain despite limited evidence supporting their use. We determined the prevalence of concomitant gabapentinoid and opioid prescriptions and evaluated their associations with outcomes among dialysis patients.

METHODS

We used the United States Renal Data System to identify patients treated with dialysis with Part A, B, and D coverage for all of 2010. Patients were grouped into 4 categories of drugs exposure status in 2010: (1) no prescriptions of either an opioid or gabapentinoid, (2) ≥1 prescription of an opioid and no prescriptions of gabapentinoids, (3) no prescriptions of an opioid and ≥1 prescription of gabapenbtinoids, (4) ≥1 prescription of both an opioid and gabapentinoid. Outcomes included 2-year all-cause death, dialysis discontinuation, and hospitalizations assessed in 2011 and 2012.

RESULTS

The study population included 153,758 dialysis patients. Concomitant prescription of an opioid and gabapentin (15%) was more common than concomitant prescription of an opioid and pregabalin (4%). In adjusted analyses, concomitant prescription of an opioid and gabapentin compared to no prescription of either was associated with increased risk of death (hazard ratio [HR] 1.16, 95% CI 1.12-1.19), dialysis discontinuation (HR 1.14, 95% CI 1.03-1.27), and hospitalization (HR 1.33, 95% CI 1.31-1.36). Concomitant prescription of an opioid and pregabalin compared to no prescription of either was associated with increased mortality (HR 1.22, 95% CI 1.16-1.28) and hospitalization (HR 1.37, 95% CI 1.33-1.41), but not dialysis discontinuation (HR 1.13, 95% CI 0.95-1.35). Prescription of opioids and gabepentinoids compared to only being prescribed opioids was associated with higher risk of hospitalizations, but not mortality, or dialysis discontinuation.

CONCLUSIONS

Concomitant prescription of opioids and gabapentinoids among US dialysis patients is common, and both drugs have independent effects on outcomes. Future research should prospectively investigate the potential harms of such drugs and identify safer alternatives for treatment of pain in end-stage renal disease patients.

Urinary phenols and parabens and diabetes among US adults, NHANES 2005-2014

BACKGROUND AND AIMS

Phenols and parabens are ubiquitous and have been associated with markers of cardiovascular health. However, the literature lacks population-based studies examining the link between these endocrine disruptors and diabetes. We examined the association between paraben/phenol concentrations and diabetes among a nationally representative sample of US adults.

METHODS AND RESULTS

We utilized data from the 2005-2014 National Health and Nutrition Examination Surveys (N = 8498). Total urinary concentrations of BPA, triclosan, BP-3, and propyl, butyl, ethyl, and methyl parabens were measured from urine specimens collected during the examination session. Diabetes status was based on self-report of a previous diagnosis or HbA1c≥6.5%. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CI) associated with the difference in log-transformed values of the 75th and 25th percentiles for each phenol/paraben, adjusting for potential confounders. The adjusted ORs (95% CI) of diabetes comparing the 75th to 25th percentiles of each paraben/phenol were 1.09 (0.96-1.23) for BPA, 0.84 (0.72-0.98) for triclosan, 0.69 (0.61-0.79) for BP-3, 0.71 (0.61-0.83) for propyl paraben, 0.66 (0.54-0.80) for butyl paraben, 0.60 (0.51-0.71) for ethyl paraben, and 0.79 (0.68-0.91) for methyl paraben.

CONCLUSIONS

Higher concentrations of triclosan, BP-3, and propyl, butyl, ethyl, and methyl parabens were associated with lower odds of diabetes. These findings warrant further investigation into the potential mechanism behind the observed associations and the temporal direction of the associations, given that we cannot rule out reverse causation. Future studies of these endocrine disruptors may improve the understanding of their relationship with diabetes.

Racial/Ethnic Disparities in Atrial Fibrillation Treatment and Outcomes among Dialysis Patients in the United States

BACKGROUND

Because stroke prevention is a major goal in the management of ESKD hemodialysis patients with atrial fibrillation, investigating racial/ethnic disparities in stroke among such patients is important to those who could benefit from strategies to maximize preventive measures.

METHODS

We used the United States Renal Data System to identify ESKD patients who initiated hemodialysis from 2006 to 2013 and then identified those with a subsequent atrial fibrillation diagnosis and Medicare Part A/B/D. Patients were followed for 1 year for all-cause stroke, mortality, prescription medications, and cardiovascular disease procedures. The survival mediational g-formula quantified the percentage of excess strokes attributable to lower use of atrial fibrillation treatments by race/ethnicity.

RESULTS

The study included 56,587 ESKD hemodialysis patients with atrial fibrillation. Black, white, Hispanic, and Asian patients accounted for 19%, 69%, 8%, and 3% of the population, respectively. Compared with white patients, black, Hispanic, or Asian patients were more likely to experience stroke (13%, 15%, and 16%, respectively) but less likely to fill a warfarin prescription (10%, 17%, and 28%, respectively). Warfarin prescription was associated with decreased stroke rates. Analyses suggested that equalizing the warfarin distribution to that in the white population would prevent 7%, 10%, and 12% of excess strokes among black, Hispanic, and Asian patients, respectively. We found no racial/ethnic disparities in all-cause mortality or use of cardiovascular disease procedures.

CONCLUSIONS

Racial/ethnic disparities in all-cause stroke among hemodialysis patients with atrial fibrillation are partially mediated by lower use of anticoagulants among black, Hispanic, and Asian patients. The reasons for these disparities are unknown, but strategies to maximize stroke prevention in minority hemodialysis populations should be further investigated.

Perceived discrimination and depressive symptoms among US Latinos: the modifying role of educational attainment

OBJECTIVE

Despite growing evidence that discrimination may contribute to poor mental health, few studies have assessed this association among US Latinos. Furthermore, the interaction between discrimination and educational attainment in shaping Latino mental health is virtually unexplored. This study aims to examine the association between perceived discrimination and depressive symptoms and the modifying role of education among a population of Mexican-origin adults.

DESIGN

We utilized population-based data from 629 Mexican-origin adults (mean age = 52.8 years) participating the Niños Lifestyle and Diabetes Study (2013-2014). Perceived discrimination was defined as responding 'sometimes' or 'often' to at least one item on the 9-item Everyday Discrimination Scale. High depressive symptoms were defined as scoring ≥10 on the CESD-10. We used log-binomial and linear-binomial models to estimate prevalence ratios (PR) and prevalence differences (PD), respectively, of high depressive symptoms for levels of perceived discrimination. Final models were adjusted for age, sex, education, cultural orientation, and nativity. General estimating equations were employed to account for within-family clustering.

RESULTS

Prevalence of perceived discrimination and high depressive symptoms were 49.5% and 29.2%, respectively. Participants experiencing discrimination had higher depressive symptom prevalence than those never or rarely experiencing discrimination [PR = 1.94, 95% confidence interval (CI): 1.46-2.58; PD = 0.19, 95% CI: 0.12-0.27]. The strength of this association varied by education level. The association between discrimination and depressive symptoms was stronger among those with >12 years of education (PR = 2.69; PD = 0.24) compared to those with ≤12 years of education (PR = 1.36; PD = 0.09).

CONCLUSION

US Latinos suffer a high burden of depressive symptoms, and discrimination may be an important driver of this burden. Our results suggest that effortful coping strategies, such as achieving high education despite high perceived discrimination, may magnify discrimination's adverse effect on Latino mental health.

Spanish Language Use Across Generations and Depressive Symptoms Among US Latinos

Acculturation markers, such as language use, have been associated with Latino depression. Language use may change between generations; however, few studies have collected intergenerational data to assess how language differences between generations impact depression. Using the Niños Lifestyle and Diabetes Study (2013-2014), we assessed how changes in Spanish language use across two generations of Mexican-origin participants in Sacramento, California, influenced offspring depressive symptoms (N = 603). High depressive symptoms were defined as CESD-10 scores ≥ 10. We used log-binomial and linear-binomial models to calculate prevalence ratios and differences, respectively, for depressive symptoms by language use, adjusting for identified confounders and within-family clustering. Decreased Spanish use and stable-equal English/Spanish use across generations protected against depressive symptoms, compared to stable-high Spanish use. Stable-low Spanish use was not associated with fewer depressive symptoms compared to stable-high Spanish use. Exposure to multiple languages cross-generationally may improve resource access and social networks that protect against depression.

How do we assess a racial disparity in health? Distribution, interaction, and interpretation in epidemiological studies

Identifying the exposures or interventions that exacerbate or ameliorate racial health disparities is one of the fundamental goals of social epidemiology. Introducing an interaction term between race and an exposure into a statistical model is commonly used in the epidemiologic literature to assess racial health disparities and the potential viability of a targeted health intervention. However, researchers may attribute too much authority to the interaction term and inadvertently ignore other salient information regarding the health disparity. In this article, we highlight empirical examples from the literature demonstrating limitations of overreliance on interaction terms in health disparities research; we further suggest approaches for moving beyond interaction terms when assessing these disparities. We promote a comprehensive framework of three guiding questions for disparity investigation, suggesting examination of the group-specific differences in (1) outcome prevalence, (2) exposure prevalence, and (3) effect size. Our framework allows for better assessment of meaningful differences in population health and the resulting implications for interventions, demonstrating that interaction terms alone do not provide sufficient means for determining how disparities arise. The widespread adoption of this more comprehensive approach has the potential to dramatically enhance understanding of the patterning of health and disease and the drivers of health disparities.

Neighborhood language isolation and depressive symptoms among elderly U.S. Latinos

PURPOSE

Neighborhood segregation related to cultural factors, such as language use, may influence elderly Latino depression. We examined the association between neighborhood-level Spanish language segregation and individual depressive symptoms among elderly Latinos.

METHODS

We linked U.S. Census language use data with geocoded population-based data from 1789 elderly Latinos (mean age = 70.6 years) participating in the Sacramento Area Latino Study on Aging (1998-2008). Neighborhood language segregation was measured with the Index of Concentration at the Extremes, which demonstrates the extent to which residents are concentrated at extremes of deprivation and privilege. We fit two-level generalized linear-mixed models with random intercepts for census tracts to quantify the association between neighborhood-level language segregation and depressive symptoms, adjusting for identified confounders.

RESULTS

After adjusting for age, sex, and nativity, residents of highly segregated Spanish-speaking neighborhoods had more depressive symptoms than those in highly segregated English-only-speaking neighborhoods (β = -4.410; 95% confidence interval [CI] = -6.851 to -1.970). This association was largely attenuated upon adjustment for individual-level education (β = -2.119; 95% CI = -4.650 to 0.413).

CONCLUSIONS

Linguistically segregated communities may benefit from targeted outreach given the high depression prevalence in these neighborhoods. Furthermore, our findings suggest that limited access to fundamental social protections, such as education, may drive the segregation-depression association among U.S. Latinos.

Educational Mobility Across Generations and Depressive Symptoms Over 10 Years Among US Latinos

Few studies have collected intergenerational data to assess the association between educational mobility across multiple generations and offspring depression. Using data from the Sacramento Area Latino Study on Aging (1998-2008), we assessed the influence of intergenerational education on depressive symptoms over 10 years among 1,786 Latino individuals (mean age = 70.6 years). Educational mobility was classified as stable-low (low parental/low offspring education), upwardly mobile (low parental/high offspring education), stable-high (high parental/high offspring education), or downwardly mobile (high parental/low offspring education). Depressive symptoms were measured with the Center for Epidemiological Studies-Depression Scale (CES-D); higher scores indicated more depressive symptoms. To quantify the association between educational mobility and CES-D scores over follow-up, we used generalized estimating equations to account for repeated CES-D measurements and adjusted for identified confounders. Within individuals, depressive symptoms remained relatively stable over follow-up. Compared with stable-low education, stable-high education and upward mobility were associated with significantly lower CES-D scores (β = -2.75 and -2.18, respectively). Downwardly mobile participants had slightly lower CES-D scores than stable-low participants (β = -0.77). Our results suggest that sustained, low educational attainment across generations may have adverse mental health consequences, and improved educational opportunities in underresourced communities may counteract the adverse influence of low parental education on Latino depression.

Perceived Racial/Ethnic Discrimination and Mental Health: a Review and Future Directions for Social Epidemiology

PURPOSE OF REVIEW

Recent literature on racial or ethnic discrimination and mental health was reviewed to assess the current science and identify key areas of emphasis for social epidemiology. Objectives of this review were to: 1) Determine whether there have been advancements in the measurement and analysis of perceived discrimination; 2) Identify the use of theories and/or frameworks in perceived discrimination and mental health research; and 3) Assess the extent to which stress buffers are being considered and evaluated in the existing literature.

RECENT FINDINGS

Metrics and analytic approaches used to assess discrimination remain largely unchanged. Theory and/or frameworks such as the stress and coping framework continue to be underused in majority of the studies. Adolescents and young adults experiencing racial/ethnic discrimination were at greater risk of adverse mental health outcomes, and the accumulation of stressors over the life course may have an aggregate impact on mental health. Some growth seems evident in studies examining the mediation and moderation of stress buffers and other key factors with the findings suggesting a reduction in the effects of discrimination on mental health.

SUMMARY

Discrimination scales should consider the multiple social identities of a person, the context where the exposure occurs, how the stressor manifests specifically in adolescents, the historical traumas, and cumulative exposure. Life course theory and intersectionality may help guide future work. Despite existing research, gaps remain in in elucidating the effects of racial and ethnic discrimination on mental health, signaling an opportunity and a call to social epidemiologists to engage in interdisciplinary research to speed research progress.

Intergenerational education mobility and depressive symptoms in a population of Mexican origin

PURPOSE

Low educational attainment has been associated with depression among Latinos. However, few studies have collected intergenerational data to assess mental health effects of educational mobility across generations.

METHODS

Using data from the Niños Lifestyle and Diabetes Study, we assessed the influence of intergenerational education on depressive symptoms among 603 Mexican-origin individuals. Intergenerational educational mobility was classified: stable-low (low parent and/or low offspring education), upwardly mobile (low parent and/or high offspring education), stable-high (high parent and/or high offspring education), or downwardly mobile (high parent and/or low offspring education). High depressive symptoms were defined as scoring ≥10 on the Center for Epidemiological Studies Depression Scale-10 (CESD-10). We examined prevalence ratios (PRs) for depressive symptoms with levels of educational mobility. We used general estimating equations with log-binomial models to account for within-family clustering, adjusting for age, gender, and offspring and parent nativity.

RESULTS

Compared with stable-low participants, the lowest prevalence of CESD-10 score ≥10 occurred in upwardly mobile (PR = 0.55; 95% confidence interval [CI] = 0.39-0.78) and stable-high (PR = 0.62; 95% CI = 0.44-0.87) participants. Downwardly mobile participants were also less likely to have a CESD-10 score ≥10 compared with stable-low participants (PR = 0.65; 95% CI = 0.38-1.11), although the estimate was not statistically significant.

CONCLUSIONS

Sustained stress from low intergenerational education may adversely affect depression. Latinos with stable-low or downwardly mobile intergenerational educational attainment may need closer monitoring for depressive symptoms.

Distal antral gastropexy - a novel technique to prevent recurrence of giant hiatus hernia in selected cases - a cohort study

INTRODUCTION

The recurrence rate of giant hiatus hernias (GHH) following repair is high (30%) and increases with the hernia size and previous revision surgery. The mechanism of recurrence is poorly understood.

METHODS

This is a retrospective cohort study of all consecutive patients who underwent repair of giant hiatus hernia in a tertiary upper GI referral centre from November 2000 to November 2014. Patients who underwent redo surgery were identified and data on intra-operative findings and procedure performed at primary and redo surgery from their operation notes were collected.

RESULTS

A total of 81 patients underwent primary repair of GHH over the 14 year study period. 10 (12.3%) had symptomatic/radiological recurrence of which 4 were found to have the distal stomach herniating into the chest despite having an intact intra-abdominal wrap/gastropexy. To prevent migration of the distal stomach into the chest, distal gastropexy - fixing the antrum to the anterior abdominal wall, was added to 'conventional' gastropexy in 5 subsequent cases, in whom the antrum was in the chest preoperatively. These cases have no evidence of recurrence at the end of 6 months follow up.

CONCLUSION

Securing the antrum of stomach to the anterior abdominal wall may prevent migration of the distal stomach and other infracolic organs into the chest and thus reduce recurrence of some GHH where antrum had been in chest previously.

Part 3. Assessment of genotoxicity and oxidative stress after exposure to diesel exhaust from U.S. 2007-compliant diesel engines: report on 1- and 3-month exposures in the ACES bioassay

Human health hazards due to diesel exhaust (DE*) exposure have been associated with both solvent and combustion components. In the past, diesel engine exhaust components have been linked to increased mutagenicity in cultures of Salmonella typhimurium and mammalian cells (Tokiwa and Ohnishi 1986). In addition, DE has been shown to increase both the incidence of tumors and the induction of 8-hydroxy-deoxyguanosine adducts (8-OHdG) in ICR mice (Ichinose et al. 1997). Furthermore, DE is composed of a complex mixture of polycyclic aromatic hydrocarbons (PAHs) and particulates. One such PAH, 3-nitrobenzanthrone (3-NBA), has been identified in DE and found in urban air. 3-NBA has been observed to induce micronucleus formation in DNA of human hepatoma cells (Lamy et al. 2004). The purpose of the current research, which is part of the Advanced Collaborative Emissions Study (ACES), a multidisciplinary program being carried out by the Health Effects Institute and the Coordinating Research Council, is to determine whether improvements in the engineering of heavy-duty diesel engines reduce the oxidative stress and genotoxic risk associated with exposure to DE components. To this end, the genotoxicity and oxidative stress of DE from an improved diesel engine was evaluated in bioassays of tissues from Wistar Han rats and C57BL/6 mice exposed to DE. Genotoxicity was measured as strand breaks using an alkaline-modified comet assay. To correlate possible DNA damage found by the comet assay, measurement of DNA-adduct formation was evaluated by a competitive enzyme-linked immunosorbent assay (ELISA) to determine the levels of free 8-OHdG found in the serum of the animals exposed to DE. 8-OHdG is a specific modified base indicating an oxidative type of DNA damage to DNA nucleotides. In addition, a thiobarbituric acid reactive substances (TBARS) assay was used to assess oxidative stress and damage in the form of lipid peroxidation in the hippocampus region of the brains of DE-exposed animals. Results from the comet assay showed no significant differences in rats between the control and exposed groups (P = 0.53, low exposure; P = 0.92, medium exposure; P = 0.77, high exposure) after 1 month of DE exposure. There were no differences between sexes in the responses of rats to these exposures. Likewise, there were no significant differences found after 3 months of exposure. Similarly, no significant differences were found between the mice exposed for 1 and 3 months to DE, nor were any differences found between sexes. Measurements of 8-OHdG in both mice and rats showed no significant difference among DE exposure groups (P = 0.46, mice; P = 0.86, rats). In mice, measured 8-OHdG was lower in the 3-month group than the 1-month group. In rats, the inverse was true. In mice, no significant differences in the levels of lipid peroxidation, as measured by TBARS, were found between the controls and DE exposure groups (P = 0.92), nor were there any differences between sexes. In rats, comparisons between the control and low-exposure groups approached significance, but no significant differences were found between the other DE exposure groups. Additionally, in rats, there were no significant differences between the 1- and 3-month DE exposure groups.

Peritonitis from an abdominal wall biloma: a unique reason to avoid prophylactic surgical drainage

Prophylactic drainage of the peritoneal space after major surgery is widely practised despite evidence against its efficacy. We describe the case of a 56-year-old woman who underwent a converted cholecystectomy and whose correctly sited abdominal drain resulted in the formation of a biloma between the external and internal oblique musculature. Subsequent leakage from the biloma into the abdominal cavity presented as peritonitis days after surgery, necessitating an emergency laparotomy. This case represents the first reported description of an abdominal wall biloma as a complication of post-cholecystectomy abdominal drainage. The evidence surrounding prophylactic drainage is discussed.

Discrete-choice preference comparison between patients and doctors for the surgical management of oesophagogastric cancer

BACKGROUND

Establishing preferences for surgery is paramount to preoperative patient counselling. This study aimed to prioritize and compare preferences of patients and doctors towards surgery for oesophagogastric cancer, to aid the counselling process.

METHODS

A discrete-choice questionnaire containing hypothetical scenarios was designed to test patient preferences for six treatment attributes: mortality, morbidity, quality of life (QoL), cure rate, hospital type and surgeon's reputation. The survey was mailed to all patients who underwent oesophagogastric cancer resection from 2008 to 2009 at two teaching hospital sites. All doctors at these sites with previous experience in counselling patients for cancer surgery were also identified and presented with the survey. Results were analysed using a random-effects probit regression model. Spearman correlation was used to compare participants' implicit choices from the discrete-choice scenarios (their true preferences) with their explicit choices from the direct ranking of preferences (their perceived preferences).

RESULTS

Eighty-one patients and 90 doctors completed the survey. Some 15 per cent of patients and 31 per cent of doctors based their choices solely on QoL. In order of importance, patients based their implicit responses on QoL (β = 1.19), cure rate (β = 0.82), morbidity (β = - 0.70), surgeon's reputation (β = 0.60), mortality (β = - 0.57) and hospital type (β = 0.26). Doctors similarly indicated QoL (β = 1.14) and hospital type (β = 0.31) as highest and lowest preferences respectively, but placed far greater emphasis on mortality (β = - 0.80) than morbidity (β = - 0.35). Implicit and explicit preferences correlated only for morbidity and surgeon's reputation in the patient cohort.

CONCLUSION

Clinicians may better meet patients' expectations and facilitate informed decision-making if QoL, cure rate and morbidity are emphasized foremost. A similar study employing preoperative patients is warranted for further clarification of preferences.

Chronic regulation of colonic epithelial secretory function by activation of G protein-coupled receptors

BACKGROUND

Enteric neurotransmitters that act at G protein-coupled receptors (GPCRs) are well known to acutely promote epithelial Cl(-) and fluid secretion. Here we examined if acute GPCR activation might have more long-term consequences for epithelial secretory function.

METHODS

Cl(-) secretion was measured as changes in short-circuit current across voltage-clamped T(84) colonic epithelial cells. Protein expression was measured by western blotting and intracellular Ca(2+) levels by Fura-2 fluorescence.

KEY RESULTS

While acute (15 min) treatment of T(84) cells with a cholinergic G(q) PCR agonist, carbachol (CCh), rapidly stimulated Cl(-) secretion, subsequent CCh-induced responses were attenuated in a biphasic manner. The first phase was transient and resolved within 6 h but this was followed by a chronic phase of attenuated responsiveness that was sustained up to 48 h. CCh-pretreatment did not chronically alter responses to another G(q)PCR agonist, histamine, or to thapsigargin or forskolin which elevate intracellular Ca(2+) and cAMP, respectively. This chronically acting antisecretory mechanism is not shared by neurotransmitters that activate G(s)PCRs. Conditioned medium from CCh-pretreated cells mimicked its chronic antisecretory actions, suggesting involvement of an epithelial-derived soluble factor but further experimentation ruled out the involvement of epidermal growth factor receptor ligands. Acute CCh exposure did not chronically alter surface expression of muscarinic M(3) receptors but inhibited intracellular Ca(2+) mobilization upon subsequent agonist challenge.

CONCLUSIONS & INFERENCES

These data reveal a novel, chronically acting, antisecretory mechanism that downregulates epithelial secretory capacity upon repeated G(q)PCR agonist exposure. This mechanism involves release of a soluble factor that uncouples receptor activation from downstream prosecretory signals.

Angelchik prosthesis with oesophageal adenocarcinoma: our surgical approach

The Angelchik prosthesis is an incomplete doughnut-shaped device composed of silicone elastomer used in the treatment of gastro-oesophageal reflux disease (GORD). It is used to encircle the lower oesophagus at the gastro-oesophageal junction (GOJ). The ease of the operation led to the insertion of over 25,000 such prostheses world-wide. However, a variety of major complications including intractable dysphagia, prosthesis migration and gastric erosion required a quarter of these devices to be removed. Development of adenocarcinoma in patients with Angelchik prosthesis is a rare occurrence. This article describes two patients who developed adenocarcinoma above their prosthesis and whose cardio-oesophagectomy was technically challenging due to the formation of a dense inflammatory capsule around the prosthesis. Our surgical approach to curative oesophageal resection with the Angelchik prosthesis in situ is also discussed.

Hodgkin's disease of appendix: report of a case

BACKGROUND

A number of cases of non Hodgkin's lymphoma of the appendix have been described, but Hodgkin's lymphoma is extremely rare. To our knowledge there are only two reports up to 1966 and none since then.

METHOD

We report a case of a 65-year-old gentleman who was treated for suspected Crohn's disease. He failed to respond to medical treatment and underwent right haemicolectomy. The resected segment of bowel demonstrated classical Hodgkin's disease originating in the appendix. He recovered well from the operation and responded well to postoperative chemotherapy.

CONCLUSION

Hodgkin's lymphoma of appendix is extremely rare. This case demonstrates the significance of repeated clinical evaluation of patients particularly in the absence of expected response to therapy.

3,4-Epoxy-1-butene, a reactive metabolite of 1,3-butadiene, induces somatic mutations in Xpc-null mice

Xpc-null (Xpc-/-) mice, deficient in the global genome repair subpathway of nucleotide excision repair (NER-GGR), were exposed by intraperitoneal (i.p.) injection to a 300 mg/kg mutagenic dose of 3,4-epoxy-1-butene (EB), to investigate NER's potential role in repairing butadiene (BD) epoxide DNA lesions. Mutagenic sensitivity was assessed using the Hprt assay. Xpc-/- mice were significantly more sensitive to EB exposure, exhibiting an average 2.8-fold increase in Hprt mutant frequency (MF) relative to those of exposed Xpc+/+ (wild-type) mice. As a positive control for NER-GGR, additional mice were exposed by i.p. injection to a 150 mg/kg mutagenic dose of benzo[a]pyrene (B[a]P). The Xpc-/- mice had MFs 2.9-fold higher than those of exposed Xpc+/+ mice. These results suggest that NER-GGR plays a role in recognizing and repairing some of the DNA adducts formed following in vivo exposure to EB. Additional research is needed to examine the response of Xpc-/- mice, as well as other NER-deficient strains, to inhaled BD. Furthermore, it is likely that alternative DNA repair pathways also are involved in restoring genomic integrity compromised by BD-epoxide DNA damage. Collaborative studies are currently underway to address these critical issues.

Assessment of 1,3-butadiene exposure in polymer production workers using HPRT mutations in lymphocytes as a biomarker

1,3-Butadiene (BD), which is used to make styrene-butadiene rubber, is a potent carcinogen in mice and a probable carcinogen, associated with leukemia, in humans. We have previously used HPRT mutation as a biomarker to evaluate exposures to BD in a monomer production plant. We now report on a study of 49 workers in a styrene-butadiene rubber plant in which we used the concentration of the BD metabolite 1,2-dihydroxy-4-(N-acetylcysteinyl-S)-butane (M1) in urine as a biomarker of exposure and the frequency of HPRT variant (mutant) lymphocytes (Vf) as a biomarker of effect. Workers were assigned to high- and low-exposure groups based on historical information about work areas and jobs. Personal exposure to BD for one work shift was measured using a passive badge dosimeter. Each participant provided a urine specimen and blood sample at the end of the work shift and completed a questionnaire providing information on lifestyle, health, and work activities. The average BD exposures in the high- and low-exposure groups were significantly different, even after excluding two extreme values, (high 1.48 ppm; low 0.15 ppm, p < 0.002). This study was done in 1994 and 1995 before the establishment, in 1996, of the new permissible exposure limit of 1 ppm. Both the mean M1 and the HPRT Vf were more than three times greater in the high-exposure group than in the low-exposure group (p < 0.0005). The three end points correlated with each other, with sample correlation coefficients between 0.4 and 0.6. The correlations among BD exposure and the biomarkers of internal exposure and genotoxicity suggest that occupational exposure to BD, in the range of 1-3 ppm, may be associated with adverse biological effects.

Biomarkers for assessing occupational exposures to 1,3-butadiene

The overall objective of this study was to evaluate a continuum of biomarkers in blood and urine for their sensitivities as indicators of low level occupational exposures to 1,3 butadiene (BD). The study design was largely cross-sectional, with biological samples collected within a short timeframe. Personal 8-h BD exposure measures were made on several occasions over a 60-day period for each potentially exposed worker in order provide maximum accuracy for this independent variable and to accommodate the different expression intervals of the several biomarkers. Co-exposures to styrene, toluene and benzene were also measured. The study included 24 BD monomer production workers (mean BD exposure=0.642 mg/m(3)), 34 polymerization workers (mean BD exposure=1.794 mg/m(3)) and 25 controls (mean BD exposure=0.023 mg/m(3)). The several biomarkers were measured by a consortium of investigators at different locations in the US and Europe. These biomarkers included: (1) metabolic genotypes (CYP2E1, EH, GST M1, GST T1, ADH2, ADH3), determined in Prague and Burlington, VT; (2) urinary M1 and M2 metabolites (1,2-dihydroxy-4-[N-acetylcysteinyl]-butane and 1-hydroxy-2-[N-acetylcysteinyl]-3-butene, respectively), determined in Albuquerque, NM and Leiden; (3) hemoglobin adducts (N-[2-dihydroxy-3-butenyl]valine=HBVal and N-[2,3,4-trihydroxybutyl]valine=THBVal), determined in Amsterdam and Chapel Hill, NC, respectively; (4) HPRT mutations determined by autoradiographic assay in Galveston, TX, with slides re-read in Burlington, VT; (6) hypoxanthine-guanine phosphoribosyltransferase (HPRT) mutations determined by cloning assay in Leiden with mutational spectra characterized in Burlington, VT; (7) sister chromatid exchanges and chromosome aberrations determined by standard methods and FISH analysis in Prague. Urinary M1 and M2 metabolites and HBVal and THBVal hemoglobin adducts were all significantly correlated with BD exposure levels, with adducts being the most highly associated. No significant relationships were observed between BD exposures and HPRT mutations or any of the cytogenetic endpoints, regardless of method of assay.

Assessment of butadiene exposure in synthetic rubber manufacturing workers in Texas using frequencies of hprt mutant lymphocytes as a biomarker

1,3-Butadiene (BD), which is used to manufacture synthetic rubber, is a mutagen and carcinogen. Because past occupational exposures have been associated with an increased risk of leukemia, there has been a dramatic reduction in workplace exposure standards. The health benefits of these reduced levels of occupational exposure to BD will be difficult to evaluate using relatively insensitive traditional epidemiological studies; however, biomarkers can be used to determine whether there are genotoxic effects associated with recent exposures to BD. In past studies of BD-exposed workers in Southeast Texas, we observed an increase in the frequency of lymphocytes with mutations in a reporter gene, hprt. Frequencies of hprt mutant cells correlated with air levels of BD and with the concentration of a BD metabolite in urine. Average exposures to 1-3 parts per million (p.p.m.) of BD were associated with a threefold increase in hprt variant (mutant) frequencies (Vfs). We now report results from a follow-up study of workers in a synthetic rubber plant in Southeast Texas. Thirty-seven workers were evaluated on three occasions over a 2-week period for exposure to BD by the use of personal organic vapor monitors and by determining the concentration of a BD metabolite in urine. The frequency of hprt mutants was determined, by autoradiography, with lymphocyte samples collected 2 weeks after the final exposure measurement. Based on their work locations, the study participants were assigned to high-exposure (N=22) or low-exposure (N=15) groups. The BD exposure, +/-standard error, of the workers in the high-exposure group (1.65+/-0.52 p.p.m.) was significantly greater than the low-exposure group (0.07+/-0.03 p.p.m.; P<0.01). The frequency of hprt mutant lymphocytes was also significantly different in the two groups (high, 10.67+/-1.5 x 10(-6); low, 3.54+/-0.6 x 10(-6); P<0.001). The concentration of the urine metabolite was greater in the high-exposure group, but the difference was not significant. The correlation coefficient between hprt Vf and BD exposure levels was r=0.44 (CI(95), 0.11-0.69; P=0.011). This study reproduced the findings from a previous study at this plant. Although studies of butadiene-exposed workers in other countries have not detected an effect of exposure on frequencies of hprt mutant lymphocytes, we have repeatedly observed this result in our studies in Texas.

Human sensitivity to 1,3-butadiene: role of microsomal epoxide hydrolase polymorphisms

1,3-Butadiene (BD) is a major commodity chemical used in the manufacture of synthetic rubber and various plastics and has been shown to be a potent animal carcinogen and a probable human carcinogen. The bioactivation of BD to reactive epoxides, and the balance between activation and detoxication of these reactive metabolites, is thought to play a critical role in the genotoxic and carcinogenic effects of BD. The detoxication of reactive BD metabolites involves enzymatic conjugation with glutathione by glutathione S-transferases (GSTs) and by hydrolysis, a reaction mediated by microsomal epoxide hydrolase (mEH). Since polymorphisms in genes of xenobiotic-metabolizing enzymes such as mEH may influence individual susceptibility to adverse health effects from BD exposure, we tested the hypothesis that the mEH Tyr113His polymorphism increases sensitivity to the genotoxic effects of BD in exposed workers. We used the autoradiographic hprt mutant lymphocyte assay as a biomarker of effect to identify genotoxicity associated with BD exposure in 49 workers from two styrene/butadiene polymer plants in Southeast Texas. Exposure to BD was assessed by collecting breathing zone air samples using passive badge dosimeters for three full 12 h work shifts 25, 20 and 14 days before blood was collected for genotyping and for the hprt assay. We genotyped the study participants for the Tyr113His polymorphism in the mEH gene and also for deletion polymorphisms in the glutathione S-transferase genes, GSTM1 and GSTT1, as potential biomarkers of susceptibility to BD. Our data indicate that the majority of the study subjects (67%) were exposed to very low levels of BD of <150 parts per billion (p.p.b.) time-weighted average (TWA). In some workers, however, we found levels of BD exposures that exceeded a TWA of 2000 p.p.b. Our data indicate a significant (P < 0.05) 2-fold increase in frequencies of hprt variant (mutant) lymphocytes (Vf) in workers exposed to >150 p.p.b. BD, compared with workers exposed to <150 p.p.b. There was no significant effect from individual GSTM1, GSTT1 or mEH genotypes in workers exposed to <150 p.p.b. BD. In workers exposed to >150 p.p.b., individuals with at least one polymorphic mEH His allele (His/His or His/Tyr genotypes) had a significant (P < 0.001) 3-fold increase in Vf (mean Vf x 10(-6) +/- SE = 13.25 +/- 1.78) compared with individuals with the Tyr/Tyr genotype (mean Vf x 10(-6) +/- SE = 4.02 +/- 0.72). There was no significant effect from individual GSTM1 or GSTT1 polymorphisms, but combined polymorphism analysis showed that the genetic damage was highest in individuals who had at least one mEH His allele and either the GSTM1 and/or GSTT1 null genotypes (hprt Vf = 14.19 +/- 2.30 x10(-6)). In contrast, this response was not observed in individuals exposed to levels of BD < 150 p.p.b. These results indicate that polymorphisms in the mEH gene may play a significant role in human sensitivity to the genotoxic effects of BD exposure, and that the hprt mutant lymphocyte assay can serve as a sensitive biomarker of genotoxicity for monitoring occupational exposure to BD in industrial settings. Additional investigations in larger populations of workers are needed to confirm our results and to characterize the possible role of additional mEH polymorphisms in the induction of genetic damage associated with occupational exposure to butadiene.

Point mutations induced by 1,2-epoxy-3-butene N1 deoxyinosine adducts

The National Toxicology Program has recently classified 1,3-butadiene (BD) as a human carcinogen. BD is metabolized to the intermediates 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane (DEB), and 1,2-dihydroxy-3,4-epoxybutane. All three metabolites have been implicated in producing specific types of DNA damage and as genotoxic agents in mice, rat, and human cells. This study has focused on EB-induced N1 deoxyinosine lesions that are formed by deamination of deoxyadenosine following reaction of the epoxide at the N(1) position. The R and S stereoisomers of this lesion were incorporated site-specifically within the context of an 11-mer oligodeoxynucleotide, incorporated into M13mp7L2 single-stranded DNA, and transfected into E. coli. Both stereoisomers modestly reduced plaque-forming ability, indicating that neither lesion presents a base modification that cannot be bypassed. The resulting plaques were assessed for point mutations using differential hybridization and DNA sequence analyses. The overall mutagenic spectrum revealed that the N1 adducts were highly mutagenic (approximately 90% per replication cycle), causing a predominance of A --> G transitions.

Effect of CYP2E1 induction by ethanol on the immunotoxicity and genotoxicity of extended low-level benzene exposure

Potential additive effects of ethanol consumption, a common life-style factor, and low-level benzene exposure, a ubiquitous environmental pollutant, were investigated. Ethanol is a potent inducer of the cytochrome P-450 2E1 (CYP2E1) enzyme, which bioactivates benzene to metabolites with known genotoxicity and immunotoxicity. A liquid diet containing 4.1% ethanol was used to induce hepatic CYP2E1 activity by 4-fold in female CD-1 mice. Groups of ethanol-treated or pair-fed control mice were exposed to benzene or filtered air in inhalation chambers for 7 h/d, 5 d/wk for 6 or 11 wk. The initial experiment focused on immunotoxicity endpoints based on literature reports that ethanol enhances high-dose benzene effects on spleen, thymus, and bone marrow cellularity and on peripheral red blood cell (RBC) and white blood cell (WBC) counts. No statistically significant alterations were found in spleen lymphocyte cellularity, subtype profile, or function (mitogen-induced proliferation, cytokine production, or natural killer cell lytic activity) after 6 wk of ethanol diet, 0.44 ppm benzene exposure, or both. This observed absence of immunomodulation by ethanol alone, a potential confounding factor, further validates our previously established murine model of sustained CYP2E1 induction by dietary ethanol. Subsequent experiments involved a 10-fold higher benzene level for a longer time of 11 wk and focused on genotoxic endpoints in known target tissues. Bone marrow and spleen cells were evaluated for DNA-protein cross-links, a sensitive transient index of genetic damage, and spleen lymphocytes were monitored for hprt-mutant frequency, a biomarker of cumulative genetic insult. No treatment-associated changes in either genotoxic endpoint were detected in animals exposed to 4.4 ppm benzene for 6 or 11 wk with or without coexposure to ethanol. Thus, our observations suggest an absence of genetic toxicity in CD-1 mice exposed to environmentally relevant levels of benzene with or without CYP2E1 induction.

Multiplex polymerase chain reaction-based analysis of T-cell receptor gamma gene rearrangements for the determination of T-lymphocyte clonality

Determination of the frequency of mutations at hprt or other loci in human lymphocytes provides a useful biomarker for human exposure to mutagens. One problem, however, is distinguishing between unique mutants and sibling mutants arising as progeny of an earlier mutant cell. We have developed a multiplex polymerase chain reaction (PCR)-based method to analyze T-cell receptor (TCR) gamma gene rearrangements for determination of T-cell clonality in mutational spectrum analysis. PCR primers for different subgroups of the V gene segment of the TCR gamma gene were selected at different sites in the TCR gamma gene so that the size of PCR products could define which V subgroup was involved in rearranged TCR gamma genes; gamma genes involving different V and J subgroups could be determined directly by PCR. Mutant T-lymphocytes with rearranged TCR gamma genes containing the same V and J subgroups were analyzed using PCR-based denaturing polyacrylamide gel electrophoresis. All of the 161 hprt mutant clones analyzed contained rearranged TCR gamma genes. Rearrangements among all subgroups of the V and J gene segments of the TCR gamma gene could be detected. VgammaI and Jgamma1/2 subgroups were involved in 69 and 71% of rearranged TCR gamma genes, respectively. This PCR-based analysis of TCR gamma gene rearrangements provides a simple and comprehensive method for identifying the clonality of mutant T-lymphocytes in human hprt mutant lymphocyte assay and mutational spectrum analysis.

Molecular analysis of hprt mutant lymphocytes from 1, 3-butadiene-exposed workers

1,3-Butadiene (BD) has been shown to be a potent animal carcinogen and a probable human carcinogen, yet the molecular mechanisms of BD genotoxicity and carcinogenicity still are not fully understood. Our hypothesis is that metabolites of BD induce specific structural changes in the human hprt gene like those observed in vitro in TK6 cells and in vivo in the mouse. Characteristic mutations in BD-exposed subjects can be identified and used as biomarkers for monitoring genotoxic effects associated with BD exposure. Molecular analysis of hprt mutant lymphocytes from BD-exposed workers and unexposed control subjects was carried out to identify changes in the structure of the hprt gene. A multiplex polymerase chain reaction (PCR) assay was used to detect exon deletions in 360 hprt mutant clones. We determined that exon deletions were significantly more frequent (P < 0.05) in BD-exposed workers (17.5%) than in control subjects (9.7%). Sequence analysis of hprt cDNA from 175 independent mutants indicated that the distribution of the types of mutations was different between the workers and the unexposed control subjects. There was a significant increase in -1 frameshift mutations in BD-exposed workers, predominantly in repeated DNA sequences, and single-base substitutions were decreased to 66% in the workers compared to 83% in the control subjects (P < 0.05). In addition to the spectral changes, hprt clonal assays revealed an elevation in mutant frequency in the lymphocytes of workers (N = 10) when compared with that in unexposed control subjects (N = 11; P < 0. 05). There also was a twofold increase of A:T --> T:A transversions in BD-exposed workers (16% in BD-exposed workers compared to 8% in controls, P = 0.25). Some of the BD-associated changes in mutational spectra observed in our study have the potential for application in monitoring genotoxic effects related to butadiene exposure.

Frequencies of hprt mutant lymphocytes in smokers, non-smokers, and former smokers

Previous work with the autoradiographic mutant lymphocyte assay has provided information about the time-course of development of hprt mutations and the persistence of detectable mutant cells in human subjects following therapeutic exposures to genotoxic agents. These early studies also revealed elevations in frequencies of mutant cells in pretreatment blood samples from patients who were current tobacco smokers, but no information was available on former smokers. In the present study, blood samples were obtained from 21 healthy former tobacco smokers who had quit smoking at least 1 year before sampling, 42 subjects who had never smoked, and 23 tobacco smokers. Plasma from all samples was tested for cotinine, a metabolite of nicotine. Current smokers were categorized as heavy smokers (> or = 10 cigarettes per day, cotinine > or = 90 ng/ml plasma) and light smokers (< 10/day, cotinine < 90 ng/ml). Lymphocytes from the blood samples were isolated, cryopreserved, and later thawed and assayed with the autoradiographic hprt assay. The 21 former tobacco smokers had a mean variant (mutant) frequency (Vf +/- standard error) of 1.97 (+/-0.13) per million evaluatable cells. The Vf of 42 subjects who had never smoked was 1.74 (+/-0.13) x 10(-6), not significantly different from the former smokers. The smokers had Vfs of 8.09 (+/-0.78) x 10(-6) for 18 heavy smokers and 5.22 (+/-1.02) x 10(-6) for five light smokers. The two categories of smokers had frequencies of mutant cells significantly different from each other, and each was significantly higher than non-smokers and former smokers (P < 0.05). Vfs were significantly correlated with both cotinine concentrations and the number of cigarettes smoked per day, P < 0.001. This study demonstrates the sensitivity of the autoradiographic hprt assay for detecting mutagenic effects related to chronic low-level exposures to genotoxins, and indicates that this assay is more likely to detect the effects of recent rather than past exposures.

Biological monitoring for mutagenic effects of occupational exposure to butadiene

The use of biological markers in the evaluation of human exposure to hazardous agents has increased rapidly in recent years. Because 1,3-butadiene is a mutagenic carcinogen, existing occupational levels of exposure may be appropriately evaluated using somatic cell mutation as a biomarker. Previously, we have described a biomarker study of workers in a butadiene monomer plant (Ward et al., 1994). We now report results from a second study of the same group of workers, conducted after plant modernization, and present preliminary results from a study of exposures in a styrene butadiene rubber (SBR) plant. Air levels of butadiene were determined using either charcoal tubes with air pumps or passive badge dosimeters. The quantity of a butadiene metabolite in the urine was used as a biomarker of exposure and the mutagenic effects of exposure were measured using the autoradiographic hprt mutant lymphocyte assay. In all three studies, the frequencies of hprt mutants were significantly elevated in workers from the areas of highest exposure when compared to workers from lower exposure areas or non-exposed subjects. The concentration of the urinary metabolite was significantly increased in high-exposed workers in the first study of monomer plant workers but not in the second. In the first monomer plant study, historical air concentrations of butadiene were higher in the production units than in the central control unit. While concurrent determined air concentrations were not elevated in the second monomer plant study, they were elevated in high exposure areas in the SBR plant study. Mutant frequencies in the lower-exposure and the non-exposed groups were consistent with historical values for non-smoking individuals who were not exposed to known mutagens. The use of biomarkers, including the hprt mutant lymphocyte assay, may be of great value in determining an appropriate occupational exposure limit for butadiene.

Identification of needs in biomarker research

Interest in the use of biological markers to evaluate future disease risk has increased greatly in recent years. Biomarkers are observable end points in a continuum of events leading from exposure to toxic agents to diseases that ultimately result from exposure. Because many significant diseases develop over long periods of time, methods for detecting early events that can predict risk are important for disease prevention. Biomarkers are generally categorized as detecting exposure, effects of exposure, or individual susceptibility to exposure. Although there has been significant progress in the technical development of biomarkers, implementation of their use in human populations has progressed much more slowly. We discuss four major needs in the development of biomarkers. First, new biomarkers need to be developed to fill gaps in our ability to observe steps in the continuum from exposure to disease. Second, the relationships between biomarker responses and disease pathology needs to be better understood. Third, the sensitivity, specificity, and variability of biomarkers need to be better characterized and they must be better validated as predictors of disease risk. Fourth, there are several societal impediments to the practical implementation of biomarker studies as public health tools. A common agreement among employers, employees, regulators, and the legal community must be established regarding appropriate and ethical uses and interpretation of biomarker data.

Repeated oral benzene exposure alters enzymes involved in benzene metabolism

Benzene is a known carcinogen and hematopoietic toxin in humans and experimental animals. The effect of acute, high-dose exposure to benzene on hepatic bioactivation and detoxication enzymes has been defined, while little is known about the effect of repeated, low-dose benzene exposure on these enzymes. Our objective was to determine whether repeated, oral benzene exposure alters enzymes involved in benzene metabolism. Specifically, we were concerned with cytochrome P-450-2E1, a bioactivation enzyme, and glutathione transferase and aldehyde dehydrogenase, two detoxifying enzymes. Female CD-1 mice were treated by gavage for 3 wk with benzene doses of 5 mg/kg (0.064 mmol/kg) or 50 mg/kg (0.646 mmol/kg) in corn oil. These doses of benzene produced 0.048 and 0.236 mumol muconic acid/d, respectively. We found that repeated exposure to 50 mg benzene/kg/d decreased P-450-2E1 activity by 34% and induced glutathione transferase activity by 30% without affecting aldehyde dehydrogenase activity. These changes in enzyme activities may serve a protective role against repeated exposure to benzene.

Progressive disruption of acinar cell calcium signaling is an early feature of cerulein-induced pancreatitis in mice

BACKGROUND & AIMS

Disruption of pancreatic exocrine secretion is an important feature of acute pancreatitis. Because cytosolic calcium is a key intracellular messenger controlling pancreatic secretion, this study examined patterns of calcium signaling during the early stages of cerulein-induced pancreatitis.

METHODS

Mice were administered hourly intraperitoneal injections of cerulein (50 micrograms/kg), and paired controls were administered saline. Acini were isolated by collagenase from pancreatic tissue harvested after injections 1, 3, 5, and 7 and were loaded with Fura-2. Individual cellular calcium responses to acetylcholine and cholecystokinin were studied using digital imaging.

RESULTS

The proportion of cells maintaining a normal oscillatory calcium response to physiological secretagogue stimulation diminished progressively after increasing cerulein injections. Also, the normal polarized spatial pattern of calcium Increase within individual acinar cells was progressively lost. A sustained response to high-dose stimulation was maintained but with diminishing amplitude. The characteristic calcium response to the Ca(2+)-adenosine triphosphatase inhibitor thapsigargin was maintained, implying that calcium reuptake and extrusion were not impaired.

CONCLUSIONS

Progressive disruption of physiological patterns of pancreatic acinar cell calcium signaling, notably in the secretory pole of the cell, is an early feature of pancreatitis induced by cerulein hyperstimulation. These changes may be important in contributing to the disruption of exocrine secretion in acute pancreatitis.

Reversible abnormalities in the ophthalmic arteries detected by color Doppler imaging

PURPOSE

To demonstrate dynamic, reversible abnormalities in ophthalmic artery blood flow velocity identified with color Doppler imaging (CDI) in patients with clinical findings of ocular ischemia with and without carotid artery stenosis.

METHODS

One patient with ocular ischemia and normal carotid arteries had abnormal ophthalmic artery velocities demonstrated by CDI. Two other patients with reversed ophthalmic artery flow and critical internal carotid artery stenosis were studied before and after carotid endarterectomy. Peak systolic and diastolic velocities as well as pulsatility indices of ophthalmic, posterior ciliary, and central retinal arteries were calculated.

RESULTS

The patient who had ocular ischemic syndrome without carotid artery stenosis showed increased ophthalmic artery velocities initially, and reversal of flow within the ophthalmic artery subsequently developed. Clinical findings and symptoms improved gradually as ophthalmic artery, posterior ciliary, and central retinal artery velocities increased. The patients with critical internal carotid artery stenosis had reversed ophthalmic artery blood flow initially which reverted to normal after carotid endarterectomy.

CONCLUSION

Ocular ischemic syndrome may occur due to abnormal blood flow in the ophthalmic artery in the absence as well as in the presence of carotid artery stenosis. Flow dynamics in the ophthalmic artery and its branches can be shown by CDI to revert toward normal as the clinical findings improve spontaneously or after opening an occluded carotid artery.

Is an elevated concentration of acinar cytosolic free ionised calcium the trigger for acute pancreatitis?

The pathogenesis of acute pancreatitis is poorly understood, despite well-recognised precipitating factors. Current evidence suggests that the earliest abnormalities of acute pancreatitis arise within acinar cells, but the key intracellular trigger has yet to be identified. Within the pancreas, physiological concentrations of secretagogues bind to G-protein-linked cell-surface receptors on acinar cells, evoking short, oscillatory spikes of acinar cytosolic-free ionised calcium ([Ca2+]i), an ubiquitous intracellular messenger. Specific effects within acinar cells include initiation of enzyme release through the phosphorylation cascades of stimulus-secretion coupling. Low resting levels of [Ca2+]i are restored by Ca(2+)-ATPase, which pumps calcium into the endoplasmic reticulum and out of the cell. If high concentrations of [Ca2+]i persist, toxicity results, intracellular signalling is disrupted, and cell damage occurs. Sustained elevations in acinar [Ca2+]i result from exposure to high concentrations of secretagogues, high doses of which also induce acute pancreatitis. Similarly, sustained elevations of [Ca2+]i may result from ductal hypertension, alcohol, hypoxia, hypercalcaemia, hyperlipidaemia, viral infection, and various drugs--all factors known to precipitate acute pancreatitis. We suggest that these factors precipitate acute pancreatitis by causing either excessive release of acinar [Ca2+]i, or damage to the integrity of mechanisms that restore low resting levels of [Ca2+]i, and that the consequent calcium toxicity is the key trigger in the pathogenesis of acute pancreatitis.