Faculty Bibliography

Rho GTPases, including the Rho, Cdc42, Rac, and ROP subfamilies, act as pivotal signaling switches in various growth and developmental processes. Compared with the well-defined role of cytoskeletal organization in Rho signaling, much less is known regarding transcriptional regulation. In a mutant screen for phenotypic enhancers of transgenic Arabidopsis plants expressing a constitutively active form of ROP2 (designated CA1-1), we identified RNA polymerase II (Pol II) C-terminal domain (CTD) phosphatase-like 1 (CPL1) as a transcriptional regulator of ROP2 signaling. We show that ROP2 activation inhibits CPL1 activity by promoting its degradation, leading to an increase in CTD Ser5 and Ser2 phosphorylation. We also observed similar modulation of CTD phosphorylation by yeast Cdc42 GTPase and enhanced degradation of the yeast CTD phosphatase Fcp1 by activated ROP2 signaling. Taken together, our results suggest that modulation of the Pol II CTD code by Rho GTPase signaling represents an evolutionarily conserved mechanism in both unicellular and multicellular eukaryotes.

OBJECTIVES/OBJECTIVE:To quantify cardiovascular disease and diabetes deaths attributable to dietary and metabolic risks by country, age, sex, and time in South Asian countries. METHODS:We used the 2010 Global Burden of Disease national surveys to characterize risk factor levels by age and sex. We derived etiological effects of risk factors-disease endpoints, by age, from meta-analyses. We defined optimal levels. We combined these inputs with cause-specific mortality rates to compute population-attributable fractions as a percentage of total cardiometabolic deaths. RESULTS:Suboptimal diet was the leading cause of cardiometabolic mortality in 4 of 5 countries, with population-attributable fractions from 40.7% (95% uncertainty interval = 37.4, 44.1) in Bangladesh to 56.9% (95% uncertainty interval = 52.4, 61.5) in Pakistan. High systolic blood pressure was the second leading cause, except in Bangladesh, where it superseded suboptimal diet. This was followed in all nations by high fasting plasma glucose, low fruit intake, and low whole grain intake. Other prominent burdens were more variable, such as low intake of vegetables, low omega-3 fats, and high sodium intake in India, Nepal, and Pakistan. CONCLUSIONS:Important similarities and differences are evident in cardiometabolic mortality burdens of modifiable dietary and metabolic risks across these countries, informing health policy and program priorities.

BACKGROUND: Gestational diabetes mellitus (GDM) is a major pregnancy complication with detrimental effects for both mothers and their children. Accumulating evidence has suggested a potential role for arsenic (As) exposure in the development of GDM, but current studies have not assessed As exposure from water, urine or toenail samples. METHODS: We investigated the association between As exposure and risk of glucose intolerance and GDM among 1151 women enrolled in the New Hampshire Birth Cohort Study. Arsenic was measured in home well water and via biomarkers (i.e., maternal urine collected ~24-28 weeks gestation and toenail clippings collected 2 weeks postpartum). RESULTS: A total of 105 (9.1 %) of women were diagnosed with glucose intolerance and 14 (1.2 %) of women were diagnosed with GDM. A total of 10.3 % of women had water As levels above 10 mug/L, with a mean As level of 4.2. Each 5 mug/L increase in As concentration in home well water was associated with a ~10 % increased odds of GDM (OR: 1.1, 95 % CI 1.0, 1.2). A positive and statistically significant association also was observed between toenail As and GDM (OR: 4.5, 95 % CI 1.2, 16.6), but not urinary arsenic (OR: 0.8, 95 % CI 0.3, 2.4). In a stratified analysis, the association between water As and GDM and glucose intolerance was largely limited to obese women (OR: 1.7, 95 % CI 1.0, 2.8). CONCLUSIONS: Our findings support the role of As exposure via water from private wells in the incidence of GDM and that this association may be modified by body composition.

AIM: To evaluate the relationship between periodontal diseases and subclinical atherosclerosis in a younger and lean South Asian population. METHODS: We conducted a cross-sectional study in 917 subjects (mean age 46 years and mean body mass index 21.1 kg/m2 ) from the Health Effects of Arsenic Longitudinal Study in Bangladesh. Multivariate linear regression models were used to assess the associations between multiple clinical measures of periodontal diseases and carotid intima-media thickness (IMT). RESULTS: Mean attachment loss (AL) and percentage of sites with AL >/= 4 mm (% AL >/= 4) were associated with increased IMT. The IMT was 20.0-mum (95% CI: 2.2, 37.8) and 26.5-mum (95% CI: 8.9, 44.1) higher in subjects in the top quartile of mean AL (>3.72 mm) and % AL >/= 4 (>58.4%), respectively, compared to those in the bottom quartile. In a subset of 366 subjects, mean AL was positively associated with plasma levels of matrix metalloproteinase-9 (p < 0.05) and soluble intercellular adhesion molecule-1 (p < 0.01). CONCLUSIONS: Attachment loss was associated with subclinical atherosclerosis in this young and lean Bangladeshi population. Future prospective studies are needed to confirm this association.

BACKGROUND:The spectrum of mortality outcomes by cause in populations with/without dyspnoea has not been determined. The study aimed to evaluate whether dyspnoea, a symptom, predicts cause-specific mortality differences between groups. The hypothesis was that diseases that result in chronic dyspnoea, those originating from the heart and lungs, would preferentially result in heart and lung disease mortality in those with baseline dyspnoea (relative to no dyspnoea) when followed over time. METHODS:A population-based sample of 11 533 Bangladeshis was recruited and followed for 11-12 years and cause-specific mortality evaluated in those with and without baseline dyspnoea. Dyspnoea was ascertained by trained physicians. The cause of death was determined by verbal autopsy. Kaplan-Meier survival curves, the Fine-Gray competing risk hazards model and logistic regression models were used to determine group differences in cause-specific mortality. RESULTS:Compared to those not reporting dyspnoea at baseline, the adjusted HRs were 6.4 (3.8 to 10.7), 9.3 (3.9 to 22.3), 1.8 (1.2 to 2.8), 2.2 (1.0 to 5.1) and 2.8 (1.3 to 6.2) for greater risk of dying from chronic obstructive pulmonary disease (COPD), asthma, heart disease, tuberculosis and lung cancer, respectively. In contrast, there was a similar risk of dying from stroke, cancer (excluding lung), liver disease, accidents and other (miscellaneous causes) between the dyspnoeic and non-dyspnoeic groups. In addition, the HR was 2.1 (1.7 to 2.5) for greater all-cause mortality in those with baseline dyspnoea versus no dyspnoea. CONCLUSIONS:Dyspnoea, ascertained by a single question with binary response, predicts heart and lung disease mortality. Individuals reporting dyspnoea were twofold to ninefold more likely to die of diseases that involve the heart and/or lungs relative to the non-dyspnoeic individuals. Therefore, in those with chronic dyspnoea, workup to look for the five common dyspnoeic diseases resulting in increased mortality (COPD, asthma, heart disease, tuberculosis and lung cancer), all treatable, should reduce mortality and improve the public health.

Early childhood is a critical stage for the foundation and development of both the microbiome and host. Early-life antibiotic exposures, cesarean section, and formula feeding could disrupt microbiome establishment and adversely affect health later in life. We profiled microbial development during the first 2 years of life in a cohort of 43 U.S. infants and identified multiple disturbances associated with antibiotic exposures, cesarean section, and formula feeding. These exposures contributed to altered establishment of maternal bacteria, delayed microbiome development, and altered alpha-diversity. These findings illustrate the complexity of early-life microbiome development and its sensitivity to perturbation.

OBJECTIVE: Carotid intima-media thickness (IMT) is a validated surrogate marker of preclinical atherosclerosis and is predictive of cardiovascular morbidity and mortality. Research on the association between IMT and diet, however, is lacking, especially in low-income countries or low-BMI populations. DESIGN: Cross-sectional analysis. Dietary intakes were measured using a validated, thirty-nine-item FFQ at baseline cohort recruitment. IMT measurements were obtained from 2010-2011. SETTING: Rural Bangladesh. SUBJECTS: Participants (n 1149) randomly selected from the Health Effects of Arsenic Longitudinal Study, an ongoing, population-based, prospective cohort study established in 2000. Average age at IMT measurement was 45.5 years. RESULTS: Principal component analysis of reported food items yielded a 'balanced' diet, an 'animal protein' diet and a 'gourd and root vegetable' diet. We observed a positive association between the gourd/root vegetable diet and IMT, as each 1 sd increase in pattern adherence was related to a difference of 7.74 (95 % CI 2.86, 12.62) mum in IMT (P<0.01), controlling for age, sex, total energy intake, smoking status, BMI, systolic blood pressure and diabetes mellitus diagnoses. The balanced pattern was associated with lower IMT (-4.95 (95 % CI -9.78, -0.11) mum for each 1sd increase of adherence; P=0.045). CONCLUSIONS: A gourd/root vegetable diet in this Bangladeshi population positively correlated with carotid IMT, while a balanced diet was associated with decreased IMT.

BACKGROUND:Exposure to inorganic arsenic (iAs), a class I carcinogen, affects several hundred million people worldwide. Once absorbed, iAs is converted to monomethylated (MMA) and then dimethylated forms (DMA), with methylation facilitating urinary excretion. The abundance of each species in urine relative to their sum (iAs%, MMA%, and DMA%) varies across individuals, reflecting differences in arsenic metabolism capacity. METHODS:The association of arsenic metabolism phenotypes with participant characteristics and arsenical skin lesions was characterized among 4,794 participants in the Health Effects of Arsenic Longitudinal Study (Araihazar, Bangladesh). Metabolism phenotypes include those obtained from principal component (PC) analysis of arsenic species. RESULTS:Two independent PCs were identified: PC1 appears to represent capacity to produce DMA (second methylation step), and PC2 appears to represent capacity to convert iAs to MMA (first methylation step). PC1 was positively associated (P <0.05) with age, female sex, and BMI, while negatively associated with smoking, arsenic exposure, education, and land ownership. PC2 was positively associated with age and education but negatively associated with female sex and BMI. PC2 was positively associated with skin lesion status, while PC1 was not. 10q24.32/AS3MT region polymorphisms were strongly associated with PC1, but not PC2. Patterns of association for most variables were similar for PC1 and DMA%, and for PC2 and MMA% with the exception of arsenic exposure and SNP associations. CONCLUSIONS:Two distinct arsenic metabolism phenotypes show unique associations with age, sex, BMI, 10q24.32 polymorphisms, and skin lesions. IMPACT/CONCLUSIONS:This work enhances our understanding of arsenic metabolism kinetics and toxicity risk profiles.