Identfying predictors of St. Louis encephalitis activity in Houston Texas

Generalized linear Poisson and logistic regression models were utilized to examine the relationship between temperature and precipitation and cases of Saint Louis encephalitis virus spread in the Houston metropolitan area. The models were investigated with and without repeated measures, with a first order autoregressive (AR1) correlation structure used for the repeated measures model. The two types of Poisson regression models, with and without correlation structure, showed that a unit increase in temperature measured in degrees Fahrenheit increases the occurrence of the virus 1.7 times and a unit increase in precipitation measured in inches increases the occurrence of the virus 1.5 times. Logistic regression did not show these covariates to be significant as predictors for encephalitis activity in Houston for either correlation structure. This discrepancy for the logistic model could be attributed to the small data set.^ Keywords: Saint Louis Encephalitis; Generalized Linear Model; Poisson; Logistic; First Order Autoregressive; Temperature; Precipitation. ^

Detection of nonrandom association of alleles from the distribution of the number of heterozygous loci in a sample.

The distribution of the number of heterozygous loci in two randomly chosen gametes or in a random diploid zygote provides information regarding the nonrandom association of alleles among different genetic loci. Two alternative statistics may be employed for detection of nonrandom association of genes of different loci when observations are made on these distributions: observed variance of the number of heterozygous loci (s2k) and a goodness-of-fit criterion (X2) to contrast the observed distribution with that expected under the hypothesis of random association of genes. It is shown, by simulation, that s2k is statistically more efficient than X2 to detect a given extent of nonrandom association. Asymptotic normality of s2k is justified, and X2 is shown to follow a chi-square (chi 2) distribution with partial loss of degrees of freedom arising because of estimation of parameters from the marginal gene frequency data. Whenever direct evaluations of linkage disequilibrium values are possible, tests based on maximum likelihood estimators of linkage disequilibria require a smaller sample size (number of zygotes or gametes) to detect a given level of nonrandom association in comparison with that required if such tests are conducted on the basis of s2k. Summarization of multilocus genotype (or haplotype) data, into the different number of heterozygous loci classes, thus, amounts to appreciable loss of information.

The association of genetic groups 1, 2, and 3 of Mycobacterium tuberculosis with pulmonary and extra-pulmonary tuberculosis

Objective. To investigate the association of the three major genetic groups of Mycobacterium tuberculosis with pulmonary and extra-pulmonary tuberculosis in clustered and non-clustered TB cases in the Houston area. ^ Study design. Secondary analysis of an ambi-directional study. ^ Study population. Three hundred fifty-eight confirmed cases of tuberculosis in the Houston that occurred between October 1995 and May 1997, who had been interviewed by the Houston T13 Initiative staff at Baylor College of Medicine, and whose isolates have had their DNA fingerprint and genetic group determined. ^ Exclusions. Individuals whose mycobacterial genotype was unknown, or whose data variables were unavailable. ^ Source of data. Laboratory results, patient interviews, and medical records at clinics and hospitals of the study population. ^ Results. In clustered cases, the majority of both, pulmonary and extra-pulmonary TB cases were caused by genetic group 1. Independent factors were assessed to determine the interactions that may influence the site of infection or increase the risk for one site or another. HIV negative males were protected against extra-pulmonary TB compared to HIV negative females. Individuals ages 1–14 years were at higher risk of having extra-pulmonary TB. Group 3 organisms were found less frequently in the total population in general, especially in extra-pulmonary disease. This supports the evidence in previous studies that this group is the least virulent and genetically distinct from the other two groups. Group 1 was found more frequently among African Americans than other ethnic groups, a trend for future investigations. ^ Among the non-clustered cases, group 2 organisms were the majority of the organisms found in both sites. They were also the majority of organisms found in African Americans, Caucasians, and Hispanics causing the majority of the infections at both sites. However, group 1 organisms were the overwhelming majority found in Asian/Pacific Islander individuals, which may indicate these organisms are either endemic to that area, or that there is an ethnic biological factor involved. This may also be due to a systematic bias, since isolates from individuals from that geographic region lack adequate copies of the insertion sequence IS6110, which leads to their placement in the non-clustered population. ^ The three genetic groups of Mycobacterium tuberculosis were not found equally distributed between sites of infection in both clustered and non-clustered cases. Furthermore, these groups were not distributed in the same patterns among the clustered and non-clustered cases, but rather in distinct patterns. ^

Case-control study of association of maternal recall of diarrhea or use of antimicrobials in the periconceptional period and neural tube defects

In June 1995 a case-control study was initiated by the Texas Department of Health among Mexican American women residing in the fourteen counties of the Texas-Mexico border. Case-women had carried infants with neural tube defect. Control-women had given birth to infants without neural tube defects. The case-control protocol included a general questionnaire which elicited information regarding illnesses experienced and antibiotics taken from three months prior to conception to three months after conception. An assessment of the associations between periconceptional diarrhea and the risk of neural tube defects indicated that the unadjusted association of diarrhea and risk of neural tube defect was significant (OR = 3.3, CI = 1.4–7.6). The unadjusted association of use of oral antimicrobials and risk of neural tube defect was also significant (OR = 3.4, CI = 1.6–7.3). These associations persisted among women who had no fever during the periconceptional period and were present irrespective of folate intake. Diarrhea was associated with an increased risk of NTD independent of use of antimicrobials. The converse was also true; antimicrobials were associated with an increased risk of NTD independent of diarrhea. Further research regarding these potentially modifiable risk factors is warranted. Replication of these findings could result in interventions in addition to folate supplementation. ^

The association of sexual behavior with oropharyngeal cancer and correlations with HPV-16 serologic status

Objectives. This hospital-based case-case study compared the characteristics of sexual behavior in patients with cancer of the oropharynx to patients with cancers of other head and neck sites. Additionally, the prevalence of certain sexual behaviors of HPV-16 seropositive head and neck cancer patients was compared to that of seronegative patients. ^ Methods. One hundred sixty five oropharyngeal cancer patients and 86 patients with cancers of other head and neck sites completed a sexual history questionnaire. ^ Results. Oropharyngeal cancer patients were significantly more likely to have had a greater number of lifetime sex partners, to have engaged in oral-genital sex, and to have had a greater number of oral-genital sex partners than non-oropharyngeal cancer patients. Oral-genital sex was significantly more common in the HPV-16 seropositive group. ^ Conclusion. These findings add to the evidence that HPV-16 is sexually transmitted to the upper aerodigestive tract and that certain sexual behaviors increase the risk for HPV-associated oropharyngeal cancer. ^

The association of HSV 1 and 2 with atherosclerosis defined by CRP level

A study of the association of Herpes simplex virus 1 and 2 exposure to early atherosclerosis using high C-reactive protein level as a marker was carried out in US born, non-pregnant, 20-49 year olds participating in a national survey between 1999 and 2004. Participants were required to have valid results for Herpes simplex virus 1 and 2 and C-Reactive Protein for inclusion. Cases were those found to have a high C-reactive protein level of 0.3-1 mg/dL, while controls had low to normal values (0.01-0.29 mg/dL). Overall, there were 1211 cases and 2870 controls. Mexican American and non-Hispanic black women were much more likely to fall into the high cardiac risk group than the other sex race groups with proportions of 44% and 39%, respectively. ^ Herpesvirus exposure was categorized such that Herpes simplex virus 1 and 2 exposure could be studied simultaneously within the same individual and models. The HSV 1+, HSV 2- category included the highest percentage (45.63%) of participants, followed by HSV 1-, HSV 2- (30.16%); HSV 1+, HSV 2+ (15.09%); and HSV 1-, HSV 2+ (9.12%) respectively. The proportion of participants in the HSV 1+, HSV 2- category was substantially higher in Mexican Americans (63%-66%). Further, the proportion in the HSV 1+, HSV 2+ category was notably higher in the non-Hispanic black participants (23%-44%). Non-Hispanic black women also had the highest percentage of HSV 1-, HSV 2+ exposure of all the sex race groups at 17%. ^ Overall, the unadjusted odds ratios for atherosclerotic disease defined by C-reactive protein with HSV 1-, HSV 2- as the referent group was 1.62 (95% CI 1.23-2.14) for HSV 1 +, HSV 2+; 1.3 (95% CI 1.10-1.69 for HSV 1+, HSV 2-; and 1.52 (95% CI 1.14-2.01). When the study was stratified into sex-race groups, only HSV 1+, HSV 2- in the Non-Hispanic white men remained significant (OR=1.6; 95% CI 1.06-2.43). Adjustment for selected covariates was made in the multivariate model for both the overall and sex-race stratified studies. High C-reactive protein values were not associated with any of the Herpesvirus exposure levels in either the overall or stratified analyses. ^

The association of food sources of calcium with weight class in adolescent girls

To determine the association of food sources of calcium with weight class in adolescent girls, the major food sources of calcium were determined for 718 sixth grade girls at three different time periods during an 18 month school-based health intervention program using a FFQ. To determine weight class, the BMI of each girl was stratified using CDC age and gender specific criteria at each time period. The percent contribution of the major food sources of calcium to total calcium intake was compared among the different weight classes at each time period, among those girls who had changed weight class at the different time periods and for those girls who did not change weight class at the different time periods. The mean total calcium intake increased by 20% between the first two time periods and by 12% between the first and last time periods with the intervention despite baseline total calcium intake already being greater than the recommended 1300 mg/day. The percent contribution of the major food sources of calcium were highly correlated among the weight classes that were compared throughout the study. Those girls who remained in the normal weight class throughout the study had the most consistent intake of food sources of calcium. Their top four food sources of calcium were different types of milk which provided greater than 50% of their total calcium intake. Despite there being no significant differences in the major food sources of calcium among the different weight classes, these data show a successful intervention for increasing calcium intake among adolescent girls. ^

The association of area socioeconomic status and cancer screening: A systematic review and multilevel study

Background. The gap between actual and ideal rates of routine cancer screening in the U.S., particularly for colorectal cancer screening (CRCS) (1;2), is responsible for an unnecessary burden of morbidity and mortality, particularly for disadvantaged groups. Knowledge about the effects of individual and area influences is being advanced by a growing body of research that has examined the association of area socioeconomic status (SES) and cancer screening after controlling for individual SES. The findings from this emerging and heterogeneous research in the cancer screening literature have been mixed. Moreover, multilevel studies in this area have not yet adequately explored the possibility of differential associations by population subgroup, despite some evidence suggesting gender-specific effects. ^ Objectives and methods. This dissertation reports on a systematic review of studies on the association of area SES and cancer screening and a multilevel study of the association between area SES and CRCS. The specific aims of the systematic review are to: (1) describe the study designs, constructs, methods, and measures; (2) describe the association of area SES and cancer screening; and (3) identify neglected areas of research. ^ The empiric study linked a pooled sample of respondents aged ≥50 years without a personal history of colorectal cancer from the 2003 and 2005 California Health Interview Surveys with a comprehensive set of census-tract level area SES measures from the 2000 U.S. Census. Two-level random intercept models were used to test 2 hypotheses: (1) area SES will be associated with adherence to two modalities of CRCS after controlling for individual SES; and (2) gender will moderate the relationship between area socioeconomic status and adherence to both modalities of CRCS. ^ Results. The systematic review identified 19 eligible studies that demonstrated variability in study designs, methods, constructs, and measures. The majority of tested associations were either not statistically significant or significant and in the positive direction, indicating that as area SES increased, the odds of CRCS increased. The multilevel study demonstrated that while multiple aspects of area SES were associated with CRCS after controlling for individual SES, associations differed by screening modality and in the case of endoscopy, they also differed by gender. ^ Conclusions. Conceptual and methodologic heterogeneity and weaknesses in the literature to date limit definitive conclusions about the underlying relationships between area SES and cancer screening. The multilevel study provided partial support for both hypotheses. Future research should continue to explore the role of gender as a moderating influence with the aim of identifying the mechanisms linking area SES and cancer prevention behaviors. ^

Association of self-reported physical activity and performance in the physical fitness assessment among Airmen

The U.S. Air Force, as with the other branches of military services, has physical fitness standards imposed on their personnel. These standards ensure a healthy and fit combat force. To meet these standards, Airmen have to maintain a certain level of physical activity in their lifestyle. Objective. This was a cross sectional (prevalence) study to evaluate the association of Airmen's self-reported physical activity and their performance in the Air Force Physical Fitness Assessment in 2007. Methods. The self-reported physical activity data were obtained from the Air Force Web Health Assessment (AF WEB HA), a web-based health questionnaire completed by the Airmen during their annual Preventive Health Assessment. The physical activity levels were categorized as having met or not having met the Centers for Disease Control and Prevention (CDC) and the American College of Sports Medicine (ACSM) physical activity recommendations. Physical Fitness scores were collected from the Air Force Fitness Management System (AFFMS), a repository of physical fitness test data. Results. There were 49,029 Airmen who answered the AF WEB HA in 2007 and also took their physical fitness test. 94.4% (n = 46,304) of Airmen met the recommended physical activity guidelines and 79.9% (n = 39,178) passed the fitness test. Total Airmen who both met the physical activity recommendations and passed the fitness test was 75.6% (n = 37,088). Airmen who did not meet the activity recommendations and also failed the fitness test totaled 635 or 1.3% of the study group. The Mantel-Haenszel Chi-Square analysis of the data on the activity levels and the physical fitness test relationship was the following χ2 = 18.52, df 1, and p = <0.0001. The Odds Ratio (OR) was 1.22 (95% CI 1.12, 1.34). Conclusion. The study determined that there was a positive association between Airmen's self-reported physical activity and their performance in the physical fitness assessment.^

The association of peer victimization and/or bullying perpetration and body dissatisfaction in elementary students from the healthy passages baseline study

This is the first U.S. study to investigate the association between peer victimization and/or bullying perpetration and body image dissatisfaction in American elementary school students. The study used data collected from the Healthy Passages baseline cohort of 5152 ethnically diverse fifth grade students from Alabama, Texas, and California. The overall prevalence of body dissatisfaction in our fifth grade sample was 50%. Students who were dissatisfied with their bodies were 23% more likely to be involved in peer victimization than students who were satisfied with their bodies (OR = 1.23; 95% CI = 1.02, 1.48). No significant associations were found between bullying status or bully-victim status and body dissatisfaction. Other factors that contributed significantly to a student's body image status were BMI, level of self-worth, level of household income, gender, pubertal timing and support received from adults (other than parents). It is noteworthy that those who were dissatisfied were heavier, came from lower income homes and were more likely to be male. Additional longitudinal studies are needed to confirm these associations, especially among large ethnically and socio-economically diverse samples. ^

The association of internet use and depression among spinal cord injury population

The purpose of this study was to exam the relationship between internet use and depression among a population of individuals who have sustained spinal cord injury. This was cross-sectional survey design conducted among spinal cord injury (SCI) patients in the Model Spinal Cord Injury System. We included a total of 1,011 SCI-patients who were interviewed face-to-face or by telephone interview over approximately a three year time period (2004–2006). All data were collected through a telephone survey which included the Patient Health Questionnaire-9 (PHQ-9) to assess depression. We examined various scales of this survey, included a reduced 3-item scale (items 1, 2 and 6) to avoid the presence of somatic symptoms among SCI patients from influencing classification of depression. The frequency of internet usage was grouped as daily/weekly/monthly/non user. Covariates examined as possible confounders included demographic characteristics, occupational status, educational level, injury type, daily function of living, pain level, self-perceived health status and satisfaction with life. We observed a negative association between the frequency of internet use and the level of depression. Daily use of internet was associated with lower PHQ-9 score and depression; however this association did not reach statistical significance after for the mentioned covariates. In conclusion, the factors related to lower depression in SCI patients who use the internet are complicated. Daily internet usage was associated with lower levels of depression. The accuracy of 3-item scale needs further validation and investigation. Further study of internet usage pattern in SCI patient is recommended. ^

Association of exogenous hormonal intake with the risk of development of hepatocellular carcinoma in women

Background. Primary liver cancer, the majority of which is hepatocellular carcinoma, is the third most common cause of mortality from cancer. It has one of the worst prognosis outcomes and an overall 5-year survival of only 5-6%. Hepatocellular carcinoma has been shown to have wide variations in geographic distribution and there is a marked difference in the incidence between different races and gender. Previously low-rate countries, including the US, have shown to have doubled the incidence of HCC during the past two decades. Even though the incidence of HCC is higher in males as compared to females, female hormones, especially estrogens have been postulated to have a role in the development of hepatocellular carcinoma on a molecular level. Despite the frequent usage of oral contraceptive pills (OCP) and previously, hormone replacement therapy (HRT), their role on HCC development has not been studied thoroughly. We aim to examine the association between exogenous hormone intake (oral contraceptives and post-menopausal hormone replacement therapy) and the development of HCC. Methods. This study is part of an ongoing hospital-based case-control study which is conducted at the Department of Gastrointestinal Oncology at The University of Texas M. D. Anderson Cancer Center. From January 2005 up to January 2008, a total of 77 women with pathologically confirmed hepatocellular carcinoma (cases) and 277 healthy women (controls) were included in the investigation. Information about the use of hormonal contraceptives, hormone replacement therapy and risk factors of hepatocellular cancer was collected by personal interview. Univariate and multivariate logistic regression analyses were done to estimate the crude odds ratios (OR) and adjusted odds ratios (AOR). Results. We found statistically significant protective effect for the use of HRT on the development of HCC, AOR=0.42 (95% CI, 0.21, 0.81). The significance was observed for estrogen replacement, AOR=0.43 (95% CI, 0.22, 0.83) and not for progesterone replacement, AOR=0.49 (95% CI, 0.10, 2.35). On the other hand, any hormonal contraceptive use, which encompasses oral contraceptive pills, implants and injections, did not show a statistical significance either in the crude OR=0.58 (95% CI, 0.33, 1.01) or AOR=0.56 (95% CI 0.26, 1.18). Conclusions. As corroborated by previous studies, HRT confers 58% HCC risk reduction among American women. The more important question of the association between hormonal contraceptives and HCC remains controversial. Further studies are warranted to explore the mechanism of the protective effect of HRT and the relationship between hormonal contraception and HCC.^

Association of maternal sphinganine:sphingosine ratio and folate levels with neural tube defects along the South Texas border

Neural tube defects (NTDs) remain elevated in Hispanic women along the South Texas Border, despite folate supplementation and folate fortification of cereal products. Missmer et al. examined the relationships between fumonisins, a class of corn mycotoxin, and NTDs in Hispanic women who ate corn tortillas and found increased odds ratios with increasing exposure, as measured by serum sphinganine:sphingosine (sa:so) ratios. This study examined the interactions between categorized maternal serum folate levels and stratified sa:so ratios and the resultant odds ratios of NTDs, stratified by type (anencephaly and spina bifida). The hypothesis was that the above normal folate category would have lower odds ratios of NTDs at given sa:so ratio categories and that there would be a difference in odds ratio patterns for anencephaly and spina bifida. Methods. Data for 406 Hispanic women were obtained from the Missmer case-control study. Sa:so ratios were calculated and subjects were stratified into “below normal,” “normal,” and above normal range for folate. A logistic regression model was applied, controlling for BMI, serum B12, lab batch, and conception date. Results. While OR’s of NTDs increased for increasing sa:so ratios, OR’s for “above normal” folate were not decreased at any sa:so ratio and there was no statistically significant difference between OR’s of anencephaly and spina bifida. Conclusion. Folate does not appear to be protective against the potential teratogenic effect of fumonisins and did not differ in effect on OR’s of NTD by type. More research is necessary to determine the extent of fumonisin exposure in Hispanic women along the South Texas Border.^