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1.  Electronic Word of Mouth on Twitter About Physical Activity in the United States: Exploratory Infodemiology Study 
Background
Twitter is a widely used social medium. However, its application in promoting health behaviors is understudied.
Objective
In order to provide insights into designing health marketing interventions to promote physical activity on Twitter, this exploratory infodemiology study applied both social cognitive theory and the path model of online word of mouth to examine the distribution of different electronic word of mouth (eWOM) characteristics among personal tweets about physical activity in the United States.
Methods
This study used 113 keywords to retrieve 1 million public tweets about physical activity in the United States posted between January 1 and March 31, 2011. A total of 30,000 tweets were randomly selected and sorted based on numbers generated by a random number generator. Two coders scanned the first 16,100 tweets and yielded 4672 (29.02%) tweets that they both agreed to be about physical activity and were from personal accounts. Finally, 1500 tweets were randomly selected from the 4672 tweets (32.11%) for further coding. After intercoder reliability scores reached satisfactory levels in the pilot coding (100 tweets separate from the final 1500 tweets), 2 coders coded 750 tweets each. Descriptive analyses, Mann-Whitney U tests, and Fisher exact tests were performed.
Results
Tweets about physical activity were dominated by neutral sentiments (1270/1500, 84.67%). Providing opinions or information regarding physical activity (1464/1500, 97.60%) and chatting about physical activity (1354/1500, 90.27%) were found to be popular on Twitter. Approximately 60% (905/1500, 60.33%) of the tweets demonstrated users’ past or current participation in physical activity or intentions to participate in physical activity. However, social support about physical activity was provided in less than 10% of the tweets (135/1500, 9.00%). Users with fewer people following their tweets (followers) (P=.02) and with fewer accounts that they followed (followings) (P=.04) were more likely to talk positively about physical activity on Twitter. People with more followers were more likely to post neutral tweets about physical activity (P=.04). People with more followings were more likely to forward tweets (P=.04). People with larger differences between number of followers and followings were more likely to mention companionship support for physical activity on Twitter (P=.04).
Conclusions
Future health marketing interventions promoting physical activity should segment Twitter users based on their number of followers, followings, and gaps between the number of followers and followings. The innovative application of both marketing and public health theory to examine tweets about physical activity could be extended to other infodemiology or infoveillance studies on other health behaviors (eg, vaccinations).
doi:10.2196/jmir.2870
PMCID: PMC3841353  PMID: 24257325
Twitter messaging; social marketing; motor activity
2.  Menstrual and reproductive characteristics and breast density in young women 
Cancer causes & control : CCC  2013;24(11):1973-1983.
Purpose
Breast density is strongly related to breast cancer risk, but determinants of breast density in young women remain largely unknown.
Methods
Associations of reproductive and menstrual characteristics with breast density measured by magnetic resonance imaging were evaluated in a cross-sectional study of 176 healthy women, 25–29 years old, using linear mixed effects models.
Results
Parity was significantly inversely associated with breast density. In multivariable adjusted models that included non-reproductive variables, mean percent dense breast volume (%DBV) decreased from 20.5 % in nulliparous women to 16.0 % in parous women, while mean absolute dense breast volume (ADBV) decreased from 85.3 to 62.5 cm3. Breast density also was significantly inversely associated with the age women started using hormonal contraceptives, whereas it was significantly positively associated with duration of hormonal contraceptive use. In adjusted models, mean %DBV decreased from 21.7 % in women who started using hormones at 12–17 years of age to 14.7 % in those who started using hormones at 22–28 years of age, while mean ADBV decreased from 86.2 to 53.7 cm3. The age at which women started using hormonal contraceptives and duration of hormone use were inversely correlated, and mean %DBV increased from 15.8 % in women who used hormones for not more than 2.0 years to 22.0 % in women who used hormones for more than 8 years, while mean ADBV increased from 61.9 to 90.4 cm3 over this interval.
Conclusions
Breast density in young women is inversely associated with parity and the age women started using hormonal contraceptives but positively associated with duration of hormone use.
doi:10.1007/s10552-013-0273-2
PMCID: PMC3960004  PMID: 23933948
Breast density; Parity; Breast feeding; Hormonal contraceptives; Menarche; Menstrual cycle
3.  Depressive Symptoms and Serum Lipid Levels in Young Adult Women 
Journal of behavioral medicine  2012;36(2):143-152.
Accumulating data suggest that depression is associated with risk factors for cardiovascular disease, but few studies have investigated potential behavioral mediators of such associations, particularly among women. In this study of healthy young adult women (n = 225), we examined associations among depressive symptoms, health behaviors, and serum lipid levels. Depressive symptoms were assessed with the 20-item Center for Epidemiologic Studies – Depression (CES-D) scale, and a fasting blood sample was obtained for serum lipid levels, including total cholesterol, high-density lipoprotein (HDL-C) and low-density lipoprotein (LDL-C). Diet was measured using 24-hour recalls, and other health behaviors (physical activity, smoking) were assessed via self-report questionnaire. Results indicated a modest negative association between depressive symptoms and LDL-C levels. Higher levels of depressive symptoms were also associated with lower total and insoluble dietary fiber intake, both of which were associated with HDL-C and LDL-C. Mediational analyses indicated a significant indirect effect of depressive symptoms on LDL-C via total and insoluble dietary fiber in unadjusted analyses, but not in adjusted analyses. The present findings suggest that depressive symptoms are inversely associated with serum LDL-C levels in young adult women, but that these associations are not likely mediated by adverse lifestyle behaviors.
doi:10.1007/s10865-012-9409-1
PMCID: PMC3376669  PMID: 22382824
Depression; cholesterol; health behaviors; diet
4.  Height, adiposity and body fat distribution and breast density in young women 
Breast Cancer Research : BCR  2012;14(4):R107.
Introduction
Breast density is one of the strongest risk factors for breast cancer, but determinants of breast density in young women remain largely unknown.
Methods
Associations of height, adiposity and body fat distribution with percentage dense breast volume (%DBV) and absolute dense breast volume (ADBV) were evaluated in a cross-sectional study of 174 healthy women, 25 to 29 years old. Adiposity and body fat distribution were measured by anthropometry and dual-energy X-ray absorptiometry (DXA), while %DBV and ADBV were measured by magnetic resonance imaging. Associations were evaluated using linear mixed-effects models. All tests of statistical significance are two-sided.
Results
Height was significantly positively associated with %DBV but not ADBV; for each standard deviation (SD) increase in height, %DBV increased by 18.7% in adjusted models. In contrast, all measures of adiposity and body fat distribution were significantly inversely associated with %DBV; a SD increase in body mass index (BMI), percentage fat mass, waist circumference and the android:gynoid fat mass ratio (A:G ratio) was each associated significantly with a 44.4 to 47.0% decrease in %DBV after adjustment for childhood BMI and other covariates. Although associations were weaker than for %DBV, all measures of adiposity and body fat distribution also were significantly inversely associated with ADBV before adjustment for childhood BMI. After adjustment for childhood BMI, however, only the DXA measures of percentage fat mass and A:G ratio remained significant; a SD increase in each was associated with a 13.8 to 19.6% decrease in ADBV. In mutually adjusted analysis, the percentage fat mass and the A:G ratio remained significantly inversely associated with %DBV, but only the A:G ratio was significantly associated with ADBV; a SD increase in the A:G ratio was associated with an 18.5% decrease in ADBV.
Conclusion
Total adiposity and body fat distribution are independently inversely associated with %DBV, whereas in mutually adjusted analysis only body fat distribution (A:G ratio) remained significantly inversely associated with ADBV in young women. Research is needed to identify biological mechanisms underlying these associations.
doi:10.1186/bcr3228
PMCID: PMC3680938  PMID: 22800711
5.  Tanning behavior among young frequent tanners is related to attitudes and not lack of knowledge about the dangers 
Health education journal  2009;68(3):232-243.
Objective
To examine the importance of tanning among students in relation to attitudes and knowledge regarding skin cancer prevention.
Design
A cross-sectional survey.
Setting
College students at a major Midwestern university
Methods
Students were recruited to complete a self-administered questionnaire that included information on sun-sensitivity, knowledge and tanning attitudes and behaviors. Survey sampling statistical techniques that account for clustering among the 163 students recruited were used.
Results
We found a high level of skin cancer prevention knowledge; however knowledge was not related to a reduction in the importance of tanning. In many cases, higher levels of knowledge corresponded to a greater emphasis on the importance of tanning. Sunscreen use was low among this population. Those who placed an importance on tanning more often checked that they believed that “sunless tanning creams are safer than the sun”.
Conclusions
This population’s belief that they look healthier and feel better with a tan strongly influences the desire to tan. Therefore, future cancer information campaigns or other prevention efforts should directly address the desire to tan by encouraging the use of sunless tanning products as an alternative method of tanning.
doi:10.1177/0017896909345195
PMCID: PMC3374486  PMID: 22707763
Knowledge; Attitudes; Cancer Prevention; Tanning; Ultraviolet Rays
6.  Adolescent attitudes towards tanning: does age matter? 
Pediatric health  2009;3(6):565-578.
Adolescents seem to be obsessed with tanning. One third of both adolescents and adults report sunbathing. On average, about 20% of adolescents report ever-using of artificial UV tanning devices with 15% currently using them. Tanning attitudes appear similar for adolescents and adults. The top three reasons for tanning included beliefs that a tan makes them more comfortable socializing with friends, looks better and is attractive. The top reason for using artificial UV tanning devices is also aesthetics, followed by relaxation. Other reasons for using artificial UV tanning devices include vacation preparation and to gain a protective base. Attitudes related to appearance that result in more frequent tanning may be difficult to change.
doi:10.2217/phe.09.55
PMCID: PMC3374604  PMID: 22707979
adolescent; attitudes; behavior; public health; skin cancer (skin neoplasms); tanning; ultraviolet rays
7.  Duration of Physical Activity and Serum 25-hydroxyvitamin D Status of Postmenopausal Women 
Annals of epidemiology  2011;21(6):440-449.
Purpose
To investigate whether the association between physical activity and serum 25-hydroxyvitamin D (25(OH)D) concentrations is independent of sun exposure, body size, and other potential explanatory variables.
Methods
Using data from a sample of 1,343 postmenopausal women, from the Women’s Health Initiative, linear regression was used to examine the associations of duration (minutes/week) of recreational activity and of yard work with 25(OH)D concentrations (nmol/L).
Results
In age-adjusted analyses, positive associations were observed between 25(OH)D concentrations and both duration of recreational physical activity (β=0.71, SE(0.09), P<0.001) and yard work (β=0.36, SE(0.10), P=0.004). After further adjustment for vitamin D intake, self-reported sunlight exposure, waist circumference, and season of blood draw, 25(OH)D was significantly associated with recreational activity (β=0.21, SE(0.09), P=0.014) but not with yard work (β=0.18, SE(0.09), P=0.061). Interactions were observed between season and both recreational activity (Pinteraction=0.082) and yard work (Pinteraction=0.038) such that these activity-25(OH)D associations were greater during summer/fall compared to winter/spring. Self-reported sunlight exposure and measures of body size did not modify the associations.
Conclusion
The observed age-adjusted activity-25(OH)D associations were attenuated after adjusting for explanatory variables and were modified by season of blood draw. Adopting a lifestyle that incorporates outdoor physical activity during summer/fall, consuming recommended amounts of vitamin D, and maintaining a healthy weight may improve or maintain vitamin D status in postmenopausal women.
doi:10.1016/j.annepidem.2010.11.011
PMCID: PMC3090482  PMID: 21414803
25-hydroxyvitamin D; vitamin D; serum; sunlight exposure; physical activity; epidemiology; women
8.  Nutrient Intake and Anemia Risk in the WHI Observational Study 
Background
Nutritional anemia among post-menopausal women is preventable; recent data on prevalence are limited.
Objective
To investigate the association between nutrient intakes and anemia prevalence, in relation to both incidence and persistence, in a longitudinal sample of post-menopausal women. We hypothesized that anemia prevalence, incidence and persistence would be greater among women reporting lower intake of B12, folate and iron.
Design
Prospective cohort analysis.
Participants/setting
Observational Cohort of the Women’s Health Initiative(WHI-OS) including 93,676 postmenopausal women, age 50 to 79 years, were recruited across the United States at 40 clinical study sites. Women were enrolled between 1993 and 1998; data collection for these analyses continued through 2000.
Main outcome measures
Anemia was defined as a blood hemoglobin concentration of <12.0 mg/dL. Persistent anemia was defined as anemia present at each measurement time point. Diet was assessed by food frequency questionnaire for iron, folate, B12, red meat and cold breakfast cereal; inadequacies were based on dietary reference intakes for women over age 50 years.
Statistical analysis
Descriptive statistics (mean and standard deviation) were used to characterize the population demographics, anemia rates and diet. Unconditional logistic regression was used to investigate associations between diet and incident and persistent anemia. Associations are presented as odds ratio (OR) and 95% confidence intervals (CI).
Results
Anemia was identified in 3,979 women or 5.5% of the cohort. Inadequate intakes of multiple anemia-associated nutrients were less frequent in non-Hispanic whites (7.4%) than other race/ethnic groups (inadequacies demonstrated in 14.6 to 16.3% of sample). Age, body mass index and smoking were associated with anemia. Women with anemia reported lower intakes of energy, protein, folate, B12, iron, vitamin C and red meat. Multiple (more than a single nutrient) dietary deficiencies were associated with a 21% greater risk of persistent anemia (OR-1.21, 95% CI: 1.05–1.41) and three deficiencies resulted in a 44% increase in risk for persistent anemia (OR-1.44, 95% CI: 1.20–1.73).
Conclusion
Inadequate nutrient intake, a modifiable condition, is associated with greater risk for anemia in post-menopausal women participating in the WHI-OS. Efforts to identify and update incidence estimates for anemia-associated nutrient deficiencies in aging women should be undertaken.
doi:10.1016/j.jada.2011.01.017
PMCID: PMC3066454  PMID: 21443985
anemia; diet; aging
9.  Adolescent Diet and Subsequent Serum Hormones, Breast Density and Bone Mineral Density in Young Women: Results of the Dietary Intervention Study in Children (DISC) Follow-Up Study 
Background
Adolescent diet is hypothesized to influence breast cancer risk. We evaluated the long-term effects of an intervention to lower fat intake among adolescent girls on biomarkers that are related to breast cancer risk in adults.
Methods
A follow-up study was conducted of 230 girls who participated in the Dietary Intervention Study in Children (DISC), in which healthy, prepubertal 8-10 year olds were randomly assigned to usual care or to a behavioral intervention that promoted a reduced fat diet. Participants were 25-29 years old at follow-up visits. All tests of statistical significance are two-sided.
Results
In analyses that did not take account of diet at the time of the follow-up visit, the only statistically significant treatment group difference was higher bone mineral content (BMC) in intervention group participants compared to usual care group participants; their mean BMCs were 2,444g and 2,377g, respectively. After adjustment for current diet, the intervention group also had statistically significantly higher bone mineral density and luteal phase serum estradiol concentrations. Serum progesterone concentrations and breast density did not differ by treatment group in unadjusted or adjusted analyses.
Conclusion
Results do not support the hypothesis that consumption of a lower fat diet during adolescence reduces breast cancer risk via effects on subsequent serum estradiol and progesterone levels, breast density or BMD.
Impact
Additional research is needed to clarify the association of adolescent diet with breast cancer risk and to determine if the results reported here are specific to the DISC intervention or more broadly applicable.
doi:10.1158/1055-9965.EPI-09-1259
PMCID: PMC2883023  PMID: 20501774

Results 1-9 (9)