Sperm mitochondrial DNA copy number mediates the association between seminal plasma selenium concentrations and semen quality among healthy men.

Selenium (Se) is essential for successful male reproduction. However, the association of Se status with human semen quality remains controversial and the underlying mechanisms are poorly understood. We measured seminal plasma Se concentrations, sperm mitochondrial DNA copy number (mtDNAcn), and sperm quality parameters among healthy Chinese men screened as potential sperm donors. Linear mixed-effects models were used to investigate the associations of within-subject pooled seminal plasma Se concentrations (n = 1159) with repeated sperm quality parameters (n = 5617); mediation analyses were applied to evaluate the mediating role of sperm mtDNAcn (n = 989). Seminal plasma Se concentrations were positively associated with sperm concentration and total count (both P for trend < 0.001). In adjusted models, men in the top vs. bottom quartiles of seminal plasma Se concentrations had 70.1 % (95 % CI: 53.3 %, 88.9 %) and 59.1 % (95 % CI: 40.5 %, 80.2 %) higher sperm concentration and total count, respectively. Meanwhile, we observed inverse associations between seminal plasma Se concentrations and sperm mtDNAcn, and between sperm mtDNAcn and sperm motility, concentration, and total count (all P for trend < 0.05). Mediation analyses suggested that sperm mtDNAcn mediated 19.7 % (95 % CI: 15.9 %, 25.3 %) and 23.1 % (95 % CI: 17.4 %, 33.4 %) of the associations between seminal plasma Se concentrations and sperm concentration and total count, respectively. Our findings suggest that Se is essential for male spermatogenesis, potentially by affecting sperm mtDNAcn.

Palbociclib-based high-throughput combination drug screening identifies synergistic therapeutic options in HPV-negative head and neck squamous cell carcinoma.

BACKGROUND: Deregulation of cell-cycle pathway is ubiquitously observed in human papillomavirus negative (HPVneg) head and neck squamous cell carcinoma (HNSCC). Despite being an attractive target, CDK4/6 inhibition using palbociclib showed modest or conflicting results as monotherapy or in combination with platinum-based chemotherapy or cetuximab in HPVneg HNSCC. Thus, innovative agents to augment the efficacy of palbociclib in HPVneg HNSCC would be welcomed. METHODS: A collection of 162 FDA-approved and investigational agents was screened in combinatorial matrix format, and top combinations were validated in a broader panel of HPVneg HNSCC cell lines. Transcriptional profiling was conducted to explore the molecular mechanisms of drug synergy. Finally, the most potent palbociclib-based drug combination was evaluated and compared with palbociclib plus cetuximab or cisplatin in a panel of genetically diverse HPVneg HNSCC cell lines and patient-derived xenograft models. RESULTS: Palbociclib displayed limited efficacy in HPVneg HNSCC as monotherapy. The high-throughput combination drug screening provided a comprehensive palbociclib-based drug-drug interaction dataset, whereas significant synergistic effects were observed when palbociclib was combined with multiple agents, including inhibitors of the PI3K, EGFR, and MEK pathways. PI3K pathway inhibitors significantly reduced cell proliferation and induced cell-cycle arrest in HPVneg HNSCC cell lines when combined with palbociclib, and alpelisib (a PI3Kα inhibitor) was demonstrated to show the most potent synergy with particularly higher efficacy in HNSCCs bearing PIK3CA alterations. Notably, when compared with cisplatin and cetuximab, alpelisib exerted stronger synergism in a broader panel of cell lines. Mechanistically, RRM2-dependent epithelial mesenchymal transition (EMT) induced by palbociclib, was attenuated by alpelisib and cetuximab rather than cisplatin. Subsequently, PDX models with distinct genetic background further validated that palbociclib plus alpelisib had significant synergistic effects in models harboring PIK3CA amplification. CONCLUSIONS: This study provides insights into the systematic combinatory effect associated with CDK4/6 inhibition and supports further initiation of clinical trials using the palbociclib plus alpelisib combination in HPVneg HNSCC with PIK3CA alterations.

Dietary fat intake and risk of Parkinson disease: results from the Swedish National March Cohort.

BACKGROUND: Following progressive aging of the population worldwide, the prevalence of Parkinson disease is expected to increase in the next decades. Primary prevention of the disease is hampered by limited knowledge of preventable causes. Recent evidence regarding diet and Parkinson disease is inconsistent and suggests that dietary habits such as fat intake may have a role in the etiology. OBJECTIVE: To investigate the association between intake of total and specific types of fat with the incidence of Parkinson disease. METHODS: Participants from the Swedish National March Cohort were prospectively followed-up from 1997 to 2016. Dietary intake was assessed at baseline using a validated food frequency questionnaire. Food items intake was used to estimate fat intake, i.e. the exposure variable, using the Swedish Food Composition Database. Total, saturated, monounsaturated and polyunsaturated fat intake were categorized into quartiles. Parkinson disease incidence was ascertained through linkages to Swedish population-based registers. Cox proportional hazards regression models were used to estimate hazard ratios (HR) with 95% confidence intervals (CI) of the association between fat intake from total or specific types of fats and the incidence of Parkinson disease. The lowest intake category was used as reference. Isocaloric substitution models were also fitted to investigate substitution effects by replacing energy from fat intake with other macronutrients or specific types of fat. RESULTS: 41,597 participants were followed up for an average of 17.6 years. Among them, 465 developed Parkinson disease. After adjusting for potential confounders, the highest quartile of saturated fat intake was associated with a 41% increased risk of Parkinson disease compared to the lowest quartile (HR Q4 vs. Q1: 1.41; 95% CI: 1.04-1.90; p for trend: 0.03). Total, monounsaturated or polyunsaturated fat intake were not significantly associated with Parkinson disease. The isocaloric substitution models did not show any effect. CONCLUSIONS: We found that a higher consumption of large amounts of saturated fat might be associated with an increased risk of Parkinson disease. A diet low in saturated fat might be beneficial for disease prevention.

Intake of Alcohol and Tea and Risk of Nasopharyngeal Carcinoma: A Population-Based Case-Control Study in Southern China.

BACKGROUND: The potential effect of alcohol or tea intake on the risk of nasopharyngeal carcinoma (NPC) remains controversial. METHODS: In a population-based case-control study in southern China, we assessed alcohol or tea intake from 2,441 histopathologically confirmed NPC cases and 2,546 controls. We calculated mean daily ethanol (g/day) and tea intake (mL/day). Fully adjusted ORs with 95% confidence intervals (CI) were estimated using logistic regression; potential dose-response trends were evaluated using restricted cubic spline analysis. RESULTS: Compared with nondrinkers, no significantly increased NPC risk in men was observed among current alcohol drinkers overall (OR, 1.08; 95% CI, 0.93-1.25), nor among current heavy drinkers (OR for ≥90 g/day ethanol vs. none, 1.32; 95% CI, 0.95-1.84) or former alcohol drinkers. Current tea drinking was associated with a decreased NPC risk (OR, 0.73; 95% CI, 0.64-0.84). Compared with never drinkers, those with the low first three quintiles of mean daily current intake of tea were at significantly lower NPC risk (OR, 0.53, 0.68, and 0.65, respectively), but not significant for the next two quintiles. Current daily tea intake had a significant nonlinear dose-response relation with NPC risk. CONCLUSIONS: Our study suggests no significant association between alcohol and NPC risk. Tea drinking may moderately reduce NPC risk, but the lack of a monotonic dose-response association complicates causal inference. IMPACT: Tea drinking might be a healthy habit for preventing NPC. More studies on biological mechanisms that may link tea with NPC risk are needed.

Survival of esophageal and gastric cancer patients with adjuvant and palliative chemotherapy-a retrospective analysis of a register-based patient cohort.

PURPOSE: The survival of esophageal and gastric cancer patients treated with chemotherapy is rarely assessed outside of clinical trials. Therefore, we compared the effectiveness of various curative or palliative chemotherapy regimens on the survival of esophageal and gastric cancer patients in a "real world" clinical setting. METHODS: We identified a cohort of 966 incident esophageal and gastric cancer patients in Stockholm/Gotland County (a low-risk Western population) during 2008-2013. Patients who received chemotherapy with curative intention (n = 279) and palliative intention (n = 182) were analyzed separately. Using Cox proportional hazards regression models, we estimated hazard ratios (HRs) with 95% confidence intervals (CIs) and adjusted for the potential confounding factors: age, sex, TNM stage, radiotherapy, comorbidity, marital status, education, income, and country of birth. RESULTS: In esophageal cancer patients with curative treatment intention, we observed a higher hazard for death among patients who received carboplatin-fluorouracil compared to patients who received cisplatin-fluorouracil, corresponding to a HR of 2.18 (95% CI 1.09-4.37). Conversely, in patients with cancer in the gastroesophageal junction who had a curative treatment intention at diagnosis, we observed a reduced hazard for death among those who received fluorouracil-oxaliplatin, compared to patients who received cisplatin-fluorouracil (HR 0.28; 95% CI 0.08-0.96). CONCLUSION: Among patients with esophageal cancer who received treatment with curative intention, cisplatin-fluorouracil was associated with better survival compared to carboplatin-fluorouracil, while patients with gastroesophageal junction cancer who were treated with cisplatin-fluorouracil had worse survival compared to fluorouracil-oxaliplatin.

Chinese nonmedicinal herbal diet and risk of nasopharyngeal carcinoma: A population-based case-control study.

BACKGROUND: An association between a nonmedicinal herbal diet and nasopharyngeal carcinoma (NPC) has often been hypothesized but never thoroughly investigated. METHODS: This study enrolled a total of 2469 patients with incident NPC and 2559 population controls from parts of Guangdong and Guangxi Provinces in southern China between 2010 and 2014. Questionnaire information was collected on the intake of traditional herbal tea and herbal soup as well as the specific herbal plants used in soups and other potentially confounding lifestyle factors. Multivariate logistic regression models were used to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for the NPC risk in association with herbal tea and soup intake. RESULTS: Ever consumption of herbal tea was not associated with NPC risk (OR, 1.03; 95% CI, 0.91-1.17). An inverse association was observed for NPC among ever drinkers of herbal soup (OR, 0.78; 95% CI, 0.67-0.90) but without any monotonic trend with an increasing frequency or duration of herbal soup consumption. Inverse associations with NPC risk were detected with 9 herbal plants used in herbal soup, including Ziziphus jujuba, Fructus lycii, Codonopsis pilosula, Astragalus membranaceus, Semen coicis, Smilax glabra, Phaseolus calcaratus, Morinda officinalis, and Atractylodes macrocephala (OR range, 0.31-0.79). CONCLUSIONS: Consuming herbal soups including specific plants, but not herbal tea, was inversely associated with NPC. If replicated, these results might provide potential for NPC prevention in endemic areas.

Deep/mixed cerebral microbleeds are associated with cognitive dysfunction through thalamocortical connectivity disruption: The Taizhou Imaging Study.

BACKGROUND: Cerebral microbleeds (CMBs) are considered to be risk factors for cognitive dysfunction. The specific pathology and clinical manifestations of CMBs are different based on their locations. We investigated the association between CMBs at different locations and cognitive dysfunction and explored the potential underlying pathways in a rural Han Chinese population. METHODS: We used baseline data from 562 community-dwelling adults (55-65 years old) in the Taizhou Imaging Study between 2013 and 2015. All individuals underwent multimodal brain magnetic resonance imaging (MRI) and 444 subjects completed neuropsychological tests: the Mini-Mental Status Examination and the Montreal Cognitive Assessment. Multinomial logistic regression was used to estimate the association between CMBs and cognitive dysfunction. The volume of brain regions and white matter microstructure were analyzed using Freesurfer and tract-based spatial statistics, respectively. RESULTS: CMBs were detected in 104 individuals (18.5%) in our study. Multinomial logistic regression found deep/mixed CMBs were associated with global cognitive dysfunction (OR 3.52; 95% CI 1.21 to 10.26), whereas lobar CMBs (OR 1.76; 95% CI 0.56 to 5.53) were not. Quantification of multimodal brain MRI showed that deep/mixed CMBs were accompanied by decreased thalamic volume and loss of fractional anisotropy of bilateral anterior thalamic radiations. CONCLUSION: Deep/mixed CMBs were associated with cognitive dysfunction in this Chinese cross-sectional study. Disruption of thalamocortical connectivity might be a potential pathway underlying this relationship.

Molecular Characterization and Identification of Stubby Root Nematode Species From Multiple States in the United States.

Stubby root nematodes (SRN) are important plant parasites infecting many crops and widely distributed in many regions of the United States. SRN transmit Tobacco rattle virus, which causes potato corky ringspot disease, thereby having a significant economic impact on the potato industry. In 2015 to 2017, 184 soil samples and 16 nematode suspensions from North Dakota, Minnesota, Idaho, Oregon, Washington, South Carolina, North Carolina, and Florida were assayed for the presence of SRN. SRN were found in 106 soil samples with population densities of 10 to 320 SRN per 200 g of soil and in eight of the nematode suspensions. Sequencing of ribosomal DNA (rDNA) or species-specific polymerase chain reaction assays revealed the presence of four SRN species, including Paratrichodorus allius, P. minor, P. porosus, and Trichodorus obtusus. Accordingly, their rDNA sequences were characterized by analyzing D2-D3 of 28S rDNA, 18S rDNA, and internal transcribed spacer (ITS) rDNA obtained in this study and retrieved from GenBank. Both intra- and interspecies variations were higher in ITS rDNA than 18S rDNA and D2-D3 of 28S rDNA. Based on phylogenetic analysis, the four SRN species formed a monophyletic group, with P. allius more closely related to P. porosus than P. minor and T. obtusus. Indel variation of ITS2 rDNA was present in P. allius populations from the same geographic regions. This study documented the occurrence of SRN species across multiple states. The intra- and interspecies genetic diversity of rDNA in this study will provide more information for understanding the evolutionary relationships of SRN and will be valuable for future studies of SRN species identification and management.

Medical History, Medication Use, and Risk of Nasopharyngeal Carcinoma.

Because persistent inflammation may render the nasopharyngeal mucosa susceptible to carcinogenesis, chronic ear-nose-throat (ENT) disease and its treatment might influence the risk of nasopharyngeal carcinoma (NPC). Existing evidence is, however, inconclusive and often based on methodologically suboptimal epidemiologic studies. In a population-based case-control study in southern China, we enrolled 2,532 persons with NPC and 2,597 controls, aged 20-74 years, from 2010 to 2014. Odds ratios were estimated for associations between NPC risk and history of ENT and related medications. Any history of chronic ENT disease was associated with a 34% increased risk of NPC. Similarly, use of nasal drops or aspirin was associated with approximately doubled risk of NPC. However, in secondary analyses restricted to chronic ENT diseases and related medication use at least 5 years prior to diagnosis/interview, most results were statistically nonsignificant, except a history of uncured ENT diseases, untreated nasal polyps, and earlier age at first diagnosis of ENT disease and first or most recent aspirin use. Overall, these findings suggest that ENT disease and related medication use are most likely early indications rather than causes of NPC, although the possibility of a modestly increased NPC risk associated with these diseases and related medications cannot be excluded.

Blood levels of trace metals and amyotrophic lateral sclerosis.

Some trace metals may increase risk of amyotrophic lateral sclerosis (ALS), whereas others may be beneficial. Our goal was to examine associations of ALS with blood levels of selenium (Se), zinc (Zn), copper (Cu), and manganese (Mn). We conducted a case-control study of 163 neurologist confirmed patients from the National Registry of Veterans with ALS and 229 frequency-matched veteran controls. We measured metal levels in blood using inductively coupled plasma mass spectrometry and estimated odds ratios (ORs) and 95% confidence intervals (CIs) for associations between ALS and a doubling of metal levels using unconditional logistic regression, adjusting for age, gender, and race/ethnicity. ALS was inversely associated with both Se (OR=0.4, 95% CI: 0.2-0.8) and Zn (OR=0.4, 95% CI: 0.2-0.8). Inverse associations with Se were stronger in patients with bulbar compared to spinal onset, worse function, longer diagnostic delay, and longer collection delay; inverse associations with Zn were stronger for those with worse function and longer collection delay. In contrast, ALS was positively associated with Cu (OR=3.4, 95% CI: 1.5-7.9). For Mn, no linear trend was evident (OR=0.9, 95% CI: 0.6-1.3, Ptrend=0.51). Associations of Se, Zn, Cu, and Mn with ALS were independent of one another. Adjustment for lead levels attenuated the positive association of ALS with Cu but did not change associations with Se, Zn, or Mn. In conclusion, Se and Zn were inversely associated with ALS, particularly among those with worse function, suggesting that supplementation with these metals may benefit such patients, while Cu was positively associated with ALS. Deficiencies of Se and Zn and excess Cu may have a role in ALS etiology.

Reducing Antibiotic Use for Young Children with Intussusception following Successful Air Enema Reduction.

China introduced a new policy regarding the management of antibiotic use. We evaluated the reasonableness of antibiotic use among children suffering from intussusception before and after policy. A retrospective study was conducted involving 234 young children with intussusception who were treated between January 1, 2011 and December 30, 2013. Demographics and detailed antibiotics regimens were collected. χ2 test was used to evaluate differences between the phase I (preintervention, n = 68) and phase II (postintervention, n = 166). We determined that the overall antibiotic use rate following successful air enema reduction was 41% (97/234), which decreased from 99% (67/68) in phase I to 18% (30/166) in phase II. In phase I, prophylactic antibiotic usage reached up to 84% (56/67). The quantity of aztreonam for injection accounted for 63% (45/71), and cefamandole nafate for injection accounted for 25% (18/71). In phases II, prophylactic antibiotic usage were reduced to 13% (4/30). The quantity of aztreonam for injection was decreased to 12% (4/33) and cefamandole nafate for injection was 3% (1/33). Antibiotics' options were more diverse. In conclusion, policy intervention was effective in addressing some aspects of antibacterial drug usage among young children with intussusception. However, excessive drug use remains a public health problem. The guidelines for the antibiotic management of intussusception for children must be established in China.

Intake of coffee, decaffeinated coffee, or tea does not affect risk for pancreatic cancer: results from the European Prospective Investigation into Nutrition and Cancer Study.

BACKGROUND & AIMS: Few modifiable risk factors have been implicated in the etiology of pancreatic cancer. There is little evidence for the effects of caffeinated coffee, decaffeinated coffee, or tea intake on risk of pancreatic cancer. We investigated the association of total coffee, caffeinated coffee, decaffeinated coffee, and tea consumption with risk of pancreatic cancer. METHODS: This study was conducted within the European Prospective Investigation into Nutrition and Cancer cohort, comprising male and female participants from 10 European countries. Between 1992 and 2000, there were 477,312 participants without cancer who completed a dietary questionnaire and were followed up to determine pancreatic cancer incidence. Coffee and tea intake was calibrated with a 24-hour dietary recall. Adjusted hazard ratios (HRs) were computed using multivariable Cox regression. RESULTS: During a mean follow-up period of 11.6 y, 865 first incidences of pancreatic cancers were reported. When divided into fourths, neither total intake of coffee (HR, 1.03; 95% confidence interval [CI], 0.83-1.27; high vs low intake), decaffeinated coffee (HR, 1.12; 95% CI, 0.76-1.63; high vs low intake), nor tea were associated with risk of pancreatic cancer (HR, 1.22, 95% CI, 0.95-1.56; high vs low intake). Moderately low intake of caffeinated coffee was associated with an increased risk of pancreatic cancer (HR, 1.33; 95% CI, 1.02-1.74), compared with low intake. However, no graded dose response was observed, and the association attenuated after restriction to histologically confirmed pancreatic cancers. CONCLUSIONS: Based on an analysis of data from the European Prospective Investigation into Nutrition and Cancer cohort, total coffee, decaffeinated coffee, and tea consumption are not related to the risk of pancreatic cancer.

Dose dependent activation of retinoic acid-inducible gene-I promotes both proliferation and apoptosis signals in human head and neck squamous cell carcinoma.

The retinoic-acid-inducible gene (RIG)-like receptor (RLR) family proteins are major pathogen reorganization receptors (PRR) responsible for detection of viral RNA, which initiates antiviral response. Here, we evaluated the functional role of one RLR family member, RIG-I, in human head and neck squamous cell carcinoma (HNSCC). RIG-I is abundantly expressed both in poorly-differentiated primary cancer and lymph node metastasis, but not in normal adjacent tissues. Activation of RIG-I by transfection with low dose of 5'-triphosphate RNA (3p-RNA) induces low levels of interferon and proinflammatory cytokines and promotes NF-κB- and Akt-dependent cell proliferation, migration and invasion. In contrast, activation of RIG-I by a high dose of 3p-RNA induces robust mitochondria-derived apoptosis accompanied by decreased activation of Akt, which is independent of the interferon and TNFα receptor, but can be rescued by over-expression of constitutively active Akt. Furthermore, co-immunoprecipitation experiments indicate that the CARD domain of RIG-I is essential for inducing apoptosis by interacting with caspase-9. Together, our results reveal a dual role of RIG-I in HNSCC through regulating activation of Akt, in which RIG-I activation by low-dose viral dsRNA increases host cell survival, whereas higher level of RIG-I activation leads to apoptosis. These findings highlight the therapeutic potential of dsRNA mediated RIG-I activation in the treatment of HNSCC.

A food pattern that is predictive of flavonol intake and risk of pancreatic cancer.

BACKGROUND: In the Multiethnic Cohort (MEC) study, we showed inverse associations between flavonols and pancreatic cancer risk. OBJECTIVE: We aimed to define a food pattern associated with intakes of quercetin, kaempferol, and myricetin; to examine the association of that pattern with pancreatic cancer risk; and to investigate the associations in an independent study. DESIGN: Reduced rank regression was applied to dietary data for 183,513 participants in the MEC. A food group pattern was extracted and simplified and applied to dietary data of 424,978 participants in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Dietary intake in both studies was assessed by using specially developed questionnaires. Multivariate Cox proportional hazards models were used to estimate relative risks for pancreatic cancer in the MEC (610 cases) and the EPIC (517 cases) studies. RESULTS: The food group pattern consisted mainly of tea, fruit, cabbage, and wine. In the MEC, inverse associations with pancreatic cancer in smokers were observed for the food group pattern [relative risk: 0.59 (95% CI: 0.31, 1.12) when extreme quintiles were compared; P for trend = 0.03]. In the EPIC study, the simplified pattern was not associated with pancreatic cancer risk (P for trend = 0.78). CONCLUSIONS: A food pattern associated with the intake of quercetin, kaempferol, and myricetin was associated with lower pancreatic cancer risk in smokers in a US-based population. However, failure to replicate the associations in an independent study weakens the conclusions and raises questions about the utility of food patterns for flavonols across populations.

Green tea and coffee intake and risk of pancreatic cancer in a large-scale, population-based cohort study in Japan (JPHC study).

Pancreatic cancer is one of the most aggressive and treatment-refractory malignancies in humans. The most effective means of reducing pancreatic cancer mortality may be primary prevention. Although laboratory studies have demonstrated that green tea possesses anticancer activities, results from epidemiological studies have failed to show a consistent cancer-preventive effect. In addition, there is a lingering concern that coffee mighty increase the risk of pancreatic cancer although the most recent epidemiological studies showed no overall association between coffee and risk. Here, we examined the association between the drinking of green tea or coffee and the risk of pancreatic cancer in a large population-based cohort study in Japan (JPHC study). In total, 102 137 participants were followed for an average of 11 years through to the end of 2003. A total of 233 incident cases of pancreatic cancer were identified among 1 116 945 person-years of follow-up. Overall, the risk of pancreatic cancer was not associated with either green tea or coffee intake in our population, although a reduced risk was apparent among men who drank at least three cups of coffee per day compared with those who did not drink any or only rarely drank coffee. In conclusion, our findings support the idea that green tea or coffee consumption does not have a substantial impact on pancreatic cancer risk in general.

Lifestyle factors and risk for symptomatic gastroesophageal reflux in monozygotic twins.

BACKGROUND & AIMS: Lifestyle and genetic factors dominate the etiology of gastroesophageal reflux disease. We investigated associations between lifestyle factors and gastroesophageal reflux (GER) symptoms, with and without controlling for genetic predisposition. METHODS: In 1967 and 1973, questionnaires including lifestyle exposures were mailed to twins in the Swedish Twin Registry, and data on GER symptoms were collected by telephone interview during 1998-2002. Two analytic methods were used: external control analysis (4083 twins with GER symptoms and 21,383 controls) and monozygotic co-twin control analysis (869 monozygotic twin pairs discordant for GER symptoms). RESULTS: In the external control analysis, leanness (body mass index [BMI] <20), upper normal weight (BMI 22.5-24.9), overweight (BMI 25-29.9), and obese (BMI > or =30) conferred -19%, 25%, 46%, and 59% increased risk of frequent GER symptoms compared with normal weight (BMI 20-22.4), respectively, among women, whereas no such associations were evident among men. When adjusted for genetic and nongenetic familial factors, these estimates were -28%, 44%, 187%, and 277%, respectively, among men. Frequent smoking rendered a 37% increased risk of frequent GER symptoms among women and 53% among men compared with nonsmokers. Physical activity at work was dose dependently associated with increased risk of frequent GER symptoms, and recreational physical activity decreased this risk. CONCLUSIONS: BMI, tobacco smoking, and physical activity at work appear to be risk factors for frequent GER symptoms, whereas recreational physical activity appears to be beneficial. Association between BMI and frequent GER symptoms among men seems to be attenuated by genetic factors.