Attenuation of fibrosis in vitro and in vivo with SPARC siRNA.

INTRODUCTION: SPARC is a matricellular protein, which, along with other extracellular matrix components including collagens, is commonly over-expressed in fibrotic diseases. The purpose of this study was to examine whether inhibition of SPARC can regulate collagen expression in vitro and in vivo, and subsequently attenuate fibrotic stimulation by bleomycin in mouse skin and lungs. METHODS: In in vitro studies, skin fibroblasts obtained from a Tgfbr1 knock-in mouse (TBR1CA; Cre-ER) were transfected with SPARC siRNA. Gene and protein expressions of the Col1a2 and the Ctgf were examined by real-time RT-PCR and Western blotting, respectively. In in vivo studies, C57BL/6 mice were induced for skin and lung fibrosis by bleomycin and followed by SPARC siRNA treatment through subcutaneous injection and intratracheal instillation, respectively. The pathological changes of skin and lungs were assessed by hematoxylin and eosin and Masson's trichrome stains. The expression changes of collagen in the tissues were assessed by real-time RT-PCR and non-crosslinked fibrillar collagen content assays. RESULTS: SPARC siRNA significantly reduced gene and protein expression of collagen type 1 in fibroblasts obtained from the TBR1CA; Cre-ER mouse that was induced for constitutively active TGF-beta receptor I. Skin and lung fibrosis induced by bleomycin was markedly reduced by treatment with SPARC siRNA. The anti-fibrotic effect of SPARC siRNA in vivo was accompanied by an inhibition of Ctgf expression in these same tissues. CONCLUSIONS: Specific inhibition of SPARC effectively reduced fibrotic changes in vitro and in vivo. SPARC inhibition may represent a potential therapeutic approach to fibrotic diseases.

Differential dynamic properties of scleroderma fibroblasts in response to perturbation of environmental stimuli.

Diseases are believed to arise from dysregulation of biological systems (pathways) perturbed by environmental triggers. Biological systems as a whole are not just the sum of their components, rather ever-changing, complex and dynamic systems over time in response to internal and external perturbation. In the past, biologists have mainly focused on studying either functions of isolated genes or steady-states of small biological pathways. However, it is systems dynamics that play an essential role in giving rise to cellular function/dysfunction which cause diseases, such as growth, differentiation, division and apoptosis. Biological phenomena of the entire organism are not only determined by steady-state characteristics of the biological systems, but also by intrinsic dynamic properties of biological systems, including stability, transient-response, and controllability, which determine how the systems maintain their functions and performance under a broad range of random internal and external perturbations. As a proof of principle, we examine signal transduction pathways and genetic regulatory pathways as biological systems. We employ widely used state-space equations in systems science to model biological systems, and use expectation-maximization (EM) algorithms and Kalman filter to estimate the parameters in the models. We apply the developed state-space models to human fibroblasts obtained from the autoimmune fibrosing disease, scleroderma, and then perform dynamic analysis of partial TGF-beta pathway in both normal and scleroderma fibroblasts stimulated by silica. We find that TGF-beta pathway under perturbation of silica shows significant differences in dynamic properties between normal and scleroderma fibroblasts. Our findings may open a new avenue in exploring the functions of cells and mechanism operative in disease development.

Mechanism of dendritic epidermal T cell-mediated tolerance induction and inhibition of proliferation

Dendritic epidermal T cells (DETC) comprise a unique population of T cells that reside in mouse epidermis and whose function remains unclear. Most DETC express a $\gamma\delta$ TCR, although some, including our DETC line, AU16, express an $\alpha\beta$ TCR. Additionally, AU16 cells express CD3, Thy-1, CD45, CD28, B7, and AsGM-1. Previous studies in our laboratory demonstrated that hapten-conjugated AU16 could induce specific immunologic tolerance in vivo and inhibit T cell proliferation in vitro. Both these activities are antigen-specific, and the induction of tolerance is non-MHC-restricted. In addition, AU16 cells are cytotoxic to a number of tumor cell lines in vitro. These studies suggested a role for these cells in immune surveillance. The purpose of my studies was to test the hypothesis that these functions of DETC (tolerance induction, inhibition of T cell proliferation, and tumor cell killing) were mediated by a cytotoxic mechanism. My specific aims were (1) to determine whether AU16 could prevent or delay tumor growth in vivo; and (2) to determine the mechanism whereby AU16 induce tolerance, using an in vitro proliferation assay. I first showed that AU16 cells killed a variety of skin tumor cell lines in vitro. I then demonstrated that they prevented melanoma growth in C3H mice when both cell types were mixed immediately prior to intradermal (i.d.) injection. Studies using the in vitro proliferation assay confirmed that DETC inhibit proliferation of T cells stimulated by hapten-bearing, antigen-presenting cells (FITC-APC). To determine which cell was the target, $\gamma$-irradiated, hapten-conjugated AU16 were added to the proliferation assay on d 4. They profoundly inhibited the proliferation of naive T cells to $\gamma$-irradiated, FITC-APC, as measured by ($\sp3$H) TdR uptake. This result strongly suggested that the T cell was the target of the AU16 activity because no APC were present by d 4 of the in vitro culture. In contrast, the addition of FITC-conjugated splenic T cells (SP-T) or lymph node T cells (LN-T) was less inhibitory. Preincubation of the T cells with FITC-AU16 cells for 24 h, followed by removal of the AU16 cells, completely inhibited the ability of the T cells to proliferate in response to FITC-APC, further supporting the conclusion that the T cell was the target of the AU16. Finally, AU16 cells were capable of killing a variety of activated T cells and T cell lines, arguing that the mechanism of proliferation inhibition, and possibly tolerance induction is one of cytotoxicity. Importantly, $\gamma\delta$ TCR$\sp+$ DETC behaved, both in vivo and in vitro like AU16, whereas other T cells did not. Therefore, these results are consistent with the hypothesis that AU16 cells are true DETC and that they induce tolerance by killing T cells that are antigen-activated in vivo. ^

The role of endogenous IFN-beta in cutaneous melanoma: Consequences of epidermal hyperplasia

The purpose of this study was to characterize epidermal hyperplasia overlying malignant melanoma, to determine the mitogenic factor responsible for the induction of this hyperplasia and to investigate its biological consequence. Whether increased keratinocyte proliferation overlying melanoma is due to production of growth factors by the tumor cells or to other mechanisms is unknown. Epidermal hyperplasia overlying human melanoma was found overlying thick (>4.0mm), but not thin (<1.0mm) tumors. Immunostaining of the sections for growth factors related to angiogenesis revealed that epidermal hyperplasia was associated with loss of IFN-β production by the keratinocytes directly overlying the tumors. Since previous studies from our laboratory have demonstrated that exogenous administration of IFN-β negatively regulates angiogenesis, we hypothesize that tumors are able to produce growth factors which stimulate the proliferation of cells in the surrounding tissues. This hyperplasia leads to a decrease in the endogenous negative regulator of angiogenesis, IFN-β. ^ The human melanoma cell line, DM-4 and several of its clones were studied to identify the mitogenic factor for keratinocytes. The expression of TGF-α directly correlated with epidermal hyperplasia in the DM-4 clones. A375SM, a human melanoma cell line that produces high levels of TGF-α, was transfected with a plasmid encoding full-length antisense TGF-α. The parental and transfected cells were implanted intradermally into nude mice. The extent of epidermal hyperplasia directly correlated with expression of TGF-α and decreased production of IFN-β, hence, increased angiogenesis. ^ In the next set of experiments, we determined the role of IFN-β on angiogenesis, tumor growth and metastasis of skin tumors. Transgenic mice containing a functional mutation in the receptor for IFN α/β were obtained. A375SM melanoma cells were implanted both s.c. and i.v. into IFN α/βR −/− mice. Tumors in the IFN α/β R −/− mice exhibited increased angiogenesis and metastasis. IFN α/βR −/− mice were exposed to chronic UV irradiation. Autochthonous tumors developed earlier in the transgenic mice than the wild-type mice. ^ Collectively, the data show that TGF-α produced by tumor cells induces proliferation of keratinocytes, leading to epidermal hyperplasia overlying malignant melanoma associated with loss of IFN-β and enhanced angiogenesis, tumorigenicity and metastasis. ^

The role of UV radiation in the development of myeloid malignancy in Rag2 knockout mice

Excessive exposure to the UV radiation present in sunlight can lead to the development of skin cancer in humans. Majority of the UV-induced skin tumors in immune-competent mice are highly antigenic in nature. Additionally, they exhibit a high frequency of mutations in the p53 gene, which arise very early in the course of UV radiation and most of them disappear before the development of skin tumors. ^ Initially, this study was to determine whether UV radiation induces skin tumors much earlier in immune deficient Rag2 knockout mice than in immune-competent mice, and if so, compare their antigenic properties and p53 mutation spectra. However, chronic UV irradiation (10 kJ/m2) induced myeloproliferative disease (MPD) as early as 4 weeks in Rag2 knockout mice instead of skin tumors. Conversely, unirradiated Rag2 knockout mice developed MPD at a low frequency, but the frequency increased with the animal's age. Although the UV-irradiated wild type mice (B6129) developed MPD, its frequency was lower and the occurrence much later than the Rag2 knockout mice. ^ This observation led to our new hypothesis that UV irradiation plays a role in the development of MPD in Rag2 knockout mice. After 4 weeks of UV radiation, both histopathology (myeloid:erythroid ratio, number of blast cells) and flow cytometry (mature myeloid, granulocytes and immature cells) demonstrated an increased number of mice affected with the disease in the UV-irradiated Rag2 knockout group than the other groups. ^ We also investigated the role of cytokines and absence of T and B cells in the development of MPD in the Rag2 knockout mice. Results indicated that IL-3 and IL-3Rα chain expression was upregulated in the spleens of the UV-irradiated Rag2 knockout mice (4 weeks). Reconstitution of the Rag2 knockout mice with T and B cells abrogated the UV-accelerated development of MPD. Both histopathology and flow cytometric analysis (mature myeloid cells, granulocytes) showed a decrease in the number of mice affected with the disease in the UV-irradiated, reconstituted group rather than any other group. In summary, this study provides the first experimental evidence that exposure to UV irradiation can lead to the development of MPD in immune deficient mice. ^

Role of the cyclin dependent kinase-4 in normal and neoplastic proliferation

In the last few years, our laboratory has studied the regulatory mechanisms of proliferation and differentiation in epidermal tissues. Our results showed differences in the roles of cyclin dependent-kinases 4 and 6, and the three D-type cyclins, during normal epidermal proliferation and neoplastic development. Thus, to elucidate the role of the different cell cycle regulators, we developed transgenic mice that overexpress CDK4 (K5-CDK4), or their cognate D-type cyclins, in epithelial tissues. The most severe phenotype was observed in K5-CDK4 animals that developed dermal fibrosis, epidermal hyperplasia and hypertrophy. Forced expression of CDK4 in the epidermal basal cell layer increased the malignant conversion of skin papillomas to squamous cell carcinomas (SCC). Contrastingly, lack of CDK4 completely inhibited tumor development, suggesting that CDK4 is required in this process. Biochemical studies demonstrated that p21 Cip1 and p27Kip1 inhibitors are sequestered by CDK4 resulting in indirect activation of Cyclin E/CDK2, implicating the non-catalytic activity of CDK4 in deregulation of the cell cycle progression. ^ It has been proposed that the proliferative and oncogenic role of Myc is linked to its ability to induce the transcription of CDK4, cyclin D1, and cyclin D2 in vitro. Deregulation of Myc oncogene has been found in several human cancers. Also it has been demonstrated that CDK4 has the ability to functionally inactivate the product of the tumor suppressor gene Rb, providing a link between Myc and the CDK4/cyclin D1/pRb/p16 pathway in some malignant tumors. Here, we sought to determine the role of CDK4 as a mediator of Myc activities by developing a Myc overexpressing mouse nullizygous for CDK4. We demonstrated that lack of CDK4 results in reduced keratinocyte proliferation and epidermal thickness in K5-Myc/CDK4-null mice. In addition, complete reversion of tumor development was observed. All together, this work demonstrates that CDK4 acts as an oncogene independent of the D-type cyclin levels and it is an important mediator of the tumorigenesis induced by Myc. In addition, we showed that the sequestering activity of CDK4 is critical for the development of epidermal hyperplasia during normal proliferation, malignant progression from papillomas to squamous cell carcinomas, and tumorigenesis induced by Myc. ^

Simulation study of joint transition and Weibull survival model with shared parameters

This study investigates a theoretical model where a longitudinal process, that is a stationary Markov-Chain, and a Weibull survival process share a bivariate random effect. Furthermore, a Quality-of-Life adjusted survival is calculated as the weighted sum of survival time. Theoretical values of population mean adjusted survival of the described model are computed numerically. The parameters of the bivariate random effect do significantly affect theoretical values of population mean. Maximum-Likelihood and Bayesian methods are applied on simulated data to estimate the model parameters. Based on the parameter estimates, predicated population mean adjusted survival can then be calculated numerically and compared with the theoretical values. Bayesian method and Maximum-Likelihood method provide parameter estimations and population mean prediction with comparable accuracy; however Bayesian method suffers from poor convergence due to autocorrelation and inter-variable correlation. ^

The relationship between risk perception and ethnicity as an explanation for late stage skin cancer diagnosis in Black and Hispanic populations: An analysis using data from the 2005 Health Information and National Trends Survey

Objective. The purpose of this study was to determine the relationship between ethnicity and skin cancer risk perception while controlling for other risk factors: education, gender, age, access to healthcare, family history of skin cancer, fear, and worry. ^ Methods. This study utilized the Health Information National Trends Survey (HINTS) dataset, a nationally representative sample of 5,586 individuals 18 years of age or older. One third of the respondents were chosen at random and asked questions involving skin cancer. Analysis was based on questions that identified skin cancer risk perception, fear of finding skin cancer, and frequency of worry about skin cancer and a variety of sociodemographic factors. ^ Results. Ethnicity had a significant impact on risk perception scores while controlling for other risk factors. Other risk factors that also had a significant impact on risk perception scores included family history of skin cancer, age, and worry. ^

Retrospective study of prevalence of Community Associated Methicillin Resistant Staphylococcus Aureus (CA-MRSA) seen in Texas MedClinics, San Antonio, TX from April 2006-August 2009

Purpose. To evaluate the presence of Community Associated–Methicillin Resistant Staphylococcus Aureus, CA-MRSA, in abscesses and skin and soft tissue infections presenting at 9 urgent care clinics in San Antonio, TX. ^ Methods. During the 40-month retrospective study (April 2006 to August 2009), wound cultures collected in 9 urgent care centers were evaluated for MRSA growth, antibiotics prescribed, follow up wound care, and antibiotic prescribing habits by physicians for all patients presenting with abscesses and skin/soft tissue infections. ^ Results. Across 9 urgent care centers in San Antonio, TX, 36,797 abscesses and cases of skin and soft tissue infections were treated during 40 months. Of the 36,797 cases, 9290 patients had wound cultures sent with 5,630 cultures sent to Texas MedClinic’s primary lab. Of the 5630 cultures sent to their primary lab, this reflected a prevalence of 4727 (84 %) cultures were positive for MRSA. Of the 9290 patients who had a wound culture sent (April 10th, 2006 to August 31st, 2009), a total of 4,307 antibiotics were prescribed. The top five antibiotics prescribed for CA-MRSA were Bactrim (55.5%), Clindamycin (18.4%), Bactroban (5%), Amoxicillin (3.5%), and Doxycycline (3%) representing 85.4% of the antibiotics prescribed. 8809/9290 (94.8%) of patients required no more than 3 follow up visits. Of the 33 physicians working full time during the entire study period, 29/33 (87.8%) of the physicians were family medicine physicians and represented varied prescribing rates of antibiotics between 11-76% with 26/33 (78.8%) of physicians prescribing antibiotics greater than 40% of the time.^ Conclusions. Abscesses and soft tissue infections are a common presenting complaint to urgent care centers. This study reveals that antibiotic-prescribing practices can be improved with physician education since this high prevalence was not known previously. Also, treating abscesses with limited packing has been shown to be a viable option in this particular circumstance and would be open field for additional clinical research. Due to the high prevalence of CA-MRSA skin and soft tissue infections among patients presenting to urgent care centers presumptive treatment for MRSA is indicated. Increasing levels of resistance to penicillin antibiotics is concerning and warrants alternative antibiotic management strategies.^

The role of workplace absence as an organizational mechanism in predicting employee alcohol and drug disorders

Background. EAP programs for airline pilots in companies with a well developed recovery management program are known to reduce pilot absenteeism following treatment. Given the costs and safety consequences to society, it is important to identify pilots who may be experiencing an AOD disorder to get them into treatment. ^ Hypotheses. This study investigated the predictive power of workplace absenteeism in identifying alcohol or drug disorders (AOD). The first hypothesis was that higher absenteeism in a 12-month period is associated with higher risk that an employee is experiencing AOD. The second hypothesis was that AOD treatment would reduce subsequent absence rates and the costs of replacing pilots on missed flights. ^ Methods. A case control design using eight years (time period) of monthly archival absence data (53,000 pay records) was conducted with a sample of (N = 76) employees having an AOD diagnosis (cases) matched 1:4 with (N = 304) non-diagnosed employees (controls) of the same profession and company (male commercial airline pilots). Cases and controls were matched on the variables age, rank and date of hire. Absence rate was defined as sick time hours used over the sum of the minimum guarantee pay hours annualized using the months the pilot worked for the year. Conditional logistic regression was used to determine if absence predicts employees experiencing an AOD disorder, starting 3 years prior to the cases receiving the AOD diagnosis. A repeated measures ANOVA, t tests and rate ratios (with 95% confidence intervals) were conducted to determine differences between cases and controls in absence usage for 3 years pre and 5 years post treatment. Mean replacement costs were calculated for sick leave usage 3 years pre and 5 years post treatment to estimate the cost of sick leave from the perspective of the company. ^ Results. Sick leave, as measured by absence rate, predicted the risk of being diagnosed with an AOD disorder (OR 1.10, 95% CI = 1.06, 1.15) during the 12 months prior to receiving the diagnosis. Mean absence rates for diagnosed employees increased over the three years before treatment, particularly in the year before treatment, whereas the controls’ did not (three years, x = 6.80 vs. 5.52; two years, x = 7.81 vs. 6.30, and one year, x = 11.00cases vs. 5.51controls. In the first year post treatment compared to the year prior to treatment, rate ratios indicated a significant (60%) post treatment reduction in absence rates (OR = 0.40, CI = 0.28, 0.57). Absence rates for cases remained lower than controls for the first three years after completion of treatment. Upon discharge from the FAA and company’s three year AOD monitoring program, case’s absence rates increased slightly during the fourth year (controls, x = 0.09, SD = 0.14, cases, x = 0.12, SD = 0.21). However, the following year, their mean absence rates were again below those of the controls (controls, x = 0.08, SD = 0.12, cases, x¯ = 0.06, SD = 0.07). Significant reductions in costs associated with replacing pilots calling in sick, were found to be 60% less, between the year of diagnosis for the cases and the first year after returning to work. A reduction in replacement costs continued over the next two years for the treated employees. ^ Conclusions. This research demonstrates the potential for workplace absences as an active organizational surveillance mechanism to assist managers and supervisors in identifying employees who may be experiencing or at risk of experiencing an alcohol/drug disorder. Currently, many workplaces use only performance problems and ignore the employee’s absence record. A referral to an EAP or alcohol/drug evaluation based on the employee’s absence/sick leave record as incorporated into company policy can provide another useful indicator that may also carry less stigma, thus reducing barriers to seeking help. This research also confirms two conclusions heretofore based only on cross-sectional studies: (1) higher absence rates are associated with employees experiencing an AOD disorder; (2) treatment is associated with lower costs for replacing absent pilots. Due to the uniqueness of the employee population studied (commercial airline pilots) and the organizational documentation of absence, the generalizability of this study to other professions and occupations should be considered limited. ^ Transition to Practice. The odds ratios for the relationship between absence rates and an AOD diagnosis are precise; the OR for year of diagnosis indicates the likelihood of being diagnosed increases 10% for every hour change in sick leave taken. In practice, however, a pilot uses approximately 20 hours of sick leave for one trip, because the replacement will have to be paid the guaranteed minimum of 20 hour. Thus, the rate based on hourly changes is precise but not practical. ^ To provide the organization with practical recommendations the yearly mean absence rates were used. A pilot flies on average, 90 hours a month, 1080 annually. Cases used almost twice the mean rate of sick time the year prior to diagnosis (T-1) compared to controls (cases, x = .11, controls, x = .06). Cases are expected to use on average 119 hours annually (total annual hours*mean annual absence rate), while controls will use 60 hours. The cases’ 60 hours could translate to 3 trips of 20 hours each. Management could use a standard of 80 hours or more of sick time claimed in a year as the threshold for unacceptable absence, a 25% increase over the controls (a cost to the company of approximately of $4000). At the 80-hour mark, the Chief Pilot would be able to call the pilot in for a routine check as to the nature of the pilot’s excessive absence. This management action would be based on a company standard, rather than a behavioral or performance issue. Using absence data in this fashion would make it an active surveillance mechanism. ^

Evaluation of risk factors for long term changes in refractive error among adult patients at a Dallas Texas private setting A retrospective chart-review study

Background. Over 39.9% of the adult population forty or older in the United States has refractive error, little is known about the etiology of this condition and associated risk factors and their entailed mechanism due to the paucity of data regarding the changes of refractive error for the adult population over time.^ Aim. To evaluate risk factors over a long term, 5-year period, in refractive error changes among persons 43 or older by testing the hypothesis that age, gender, systemic diseases, nuclear sclerosis and baseline refractive errors are all significantly associated with refractive errors changes in patients at a Dallas, Texas private optometric office.^ Methods. A retrospective chart review of subjective refraction, eye health, and self-report health history was done on patients at a private optometric office who were 43 or older in 2000 who had eye examinations both in 2000 and 2005. Aphakic and pseudophakic eyes were excluded as well as eyes with best corrected Snellen visual acuity of 20/40 and worse. After exclusions, refraction was obtained on 114 right eyes and 114 left eyes. Spherical equivalent (sum of sphere + ½ cylinder) was used as the measure of refractive error.^ Results. Similar changes in refractive error were observed for the two eyes. The 5-year change in spherical power was in a hyperopic direction for younger age groups and in a myopic direction for older subjects, P<0.0001. The gender-adjusted mean change in refractive error in right eyes of persons aged 43 to 54, 55 to 64, 65 to 74, and 75 or older at baseline was +0.43D, +0.46 D, -0.09 D, and -0.23D, respectively. Refractive change was strongly related to baseline nuclear cataract severity; grades 4 to 5 were associated with a myopic shift (-0.38 D, P< 0.0001). The mean age-adjusted change in refraction was +0.27 D for hyperopic eyes, +0.56 D for emmetropic eyes, and +0.26 D for myopic eyes.^ Conclusions. This report has documented refractive error changes in an older population and confirmed reported trends of a hyperopic shift before age 65 and a myopic shift thereafter associated with the development of nuclear cataract.^

Selection of body fat distribution indices in adults and associations with plasma lipid metabolism variables

Body fat distribution is a cardiovascular health risk factor in adults. Body fat distribution can be measured through various methods including anthropometry. It is not clear which anthropometric index is suitable for epidemiologic studies of fat distribution and cardiovascular disease. The purpose of the present study was to select a measure of body fat distribution from among a series of indices (those traditionally used in the literature and others constructed from the analysis) that is most highly correlated with lipid-related variables and is independent of overall fatness. Subjects were Mexican-American men and women (N = 1004) from a study of gallbladder disease in Starr County, Texas. Multivariate associations were sought between lipid profile measures (lipids, lipoproteins, and apolipoproteins) and two sets of anthropometric variables (4 circumferences and 6 skinfolds). This was done to assess the association between lipid-related measures and the two sets of anthropometric variables and guide the construction of indices.^ Two indices emerged from the analysis that seemed to be highly correlated with lipid profile measures independent of obesity. These indices are: 2*arm circumference-thigh skinfold in pre- and post-menopausal women and arm/thigh circumference ratio in men. Next, using the sum of all skinfolds to represent obesity and the selected body fat distribution indices, the following hypotheses were tested: (1) state of obesity and centrally/upper distributed body fat are equally predictive of lipids, lipoproteins and apolipoproteins, and (2) the correlation among the lipid-related measures is not altered by obesity and body fat distribution.^ With respect to the first hypothesis, the present study found that most lipids, lipoproteins and apolipoproteins were significantly associated with both overall fatness and anatomical location of body fat in both sex and menopausal groups. However, within men and post-menopausal women, certain lipid profile measures (triglyceride and HDLT among post-menopausal women and apos C-II, CIII, and E among men) had substantially higher correlation with body fat distribution as compared with overall fatness.^ With respect to the second hypothesis, both obesity and body fat distribution were found to alter the association among plasma lipid variables in men and women. There was a suggestion from the data that the pattern of correlations among men and post-menopausal women are more comparable. Among men correlations involving apo A-I, HDLT, and HDL$\sb2$ seemed greatly influenced by obesity, and A-II by fat distribution; among post-menopausal women correlations involving apos A-I and A-II were highly affected by the location of body fat.^ Thus, these data point out that not only can obesity and fat distribution affect levels of single measures, they also can markedly influence the pattern of relationship among measures. The fact that such changes are seen for both obesity and fat distribution is significant, since the indices employed were chosen because they were independent of one another. ^

Validity of using item response theory to analyze data from the Work Limitations Questionnaire

The Work Limitations Questionnaire (WLQ) is used to determine the amount of work loss and productivity which stem from certain health conditions, including rheumatoid arthritis and cancer. The questionnaire is currently scored using methodology from Classical Test Theory. Item Response Theory, on the other hand, is a theory based on analyzing item responses. This study wanted to determine the validity of using Item Response Theory (IRT), to analyze data from the WLQ. Item responses from 572 employed adults with dysthymia, major depressive disorder (MDD), double depressive disorder (both dysthymia and MDD), rheumatoid arthritis and healthy individuals were used to determine the validity of IRT (Adler et al., 2006).^ PARSCALE, which is IRT software from Scientific Software International, Inc., was used to calculate estimates of the work limitations based on item responses from the WLQ. These estimates, also known as ability estimates, were then correlated with the raw score estimates calculated from the sum of all the items responses. Concurrent validity, which claims a measurement is valid if the correlation between the new measurement and the valid measurement is greater or equal to .90, was used to determine the validity of IRT methodology for the WLQ. Ability estimates from IRT were found to be somewhat highly correlated with the raw scores from the WLQ (above .80). However, the only subscale which had a high enough correlation for IRT to be considered valid was the time management subscale (r = .90). All other subscales, mental/interpersonal, physical, and output, did not produce valid IRT ability estimates.^ An explanation for these lower than expected correlations can be explained by the outliers found in the sample. Also, acquiescent responding (AR) bias, which is caused by the tendency for people to respond the same way to every question on a questionnaire, and the multidimensionality of the questionnaire (the WLQ is composed of four dimensions and thus four different latent variables) probably had a major impact on the IRT estimates. Furthermore, it is possible that the mental/interpersonal dimension violated the monotonocity assumption of IRT causing PARSCALE to fail to run for these estimates. The monotonicity assumption needs to be checked for the mental/interpersonal dimension. Furthermore, the use of multidimensional IRT methods would most likely remove the AR bias and increase the validity of using IRT to analyze data from the WLQ.^

Associations between ambient levels of combustion pollutants and small for gestational age infants in Texas

There is scant evidence regarding the associations between ambient levels of combustion pollutants and small for gestational age (SGA) infants. No studies of this type have been completed in the Southern United States. The main objective of the project presented was to determine associations between combustion pollutants and SGA infants in Texas using three different exposure assessments. ^ Birth certificate data that contained information on maternal and infant characteristics were obtained from the Texas Department of State Health Services (TX DSHS). Exposure assessment data for the three aims came from: (1) U.S. Environmental Protection Agency (EPA) National Air Toxics Assessment (NATA), (2) U.S. EPA Air Quality System (AQS), and (3) TX Department of Transportation (DOT), respectively. Multiple logistic regression models were used to determine the associations between combustion pollutants and SGA. ^ For the first study looked at annual estimates of four air toxics at the census tract level in the Greater Houston Area. After controlling for maternal race, maternal education, tobacco use, maternal age, number of prenatal visits, marital status, maternal weight gain, and median census tract income level, adjusted ORs and 95% confidence intervals (CI) for exposure to PAHs (per 10 ng/m3), naphthalene (per 10 ng/m3), benzene (per 1 µg/m3), and diesel engine emissions (per 10 µg/m3) were 1.01 (0.97–1.05), 1.00 (0.99–1.01), 1.01 (0.97–1.05), and 1.08 (0.95–1.23) respectively. For the second study looking at Hispanics in El Paso County, AORs and 95% confidence intervals (CI) for increases of 5 ng/m3 for the sum of carcinogenic PAHs (Σ c-PAHs), 1 ng/m3 of benzo[a]pyrene, and 100 ng/m3 in naphthalene during the third trimester of pregnancy were 1.02 (0.97–1.07), 1.03 (0.96–1.11), and 1.01 (0.97–1.06), respectively. For the third study using maternal proximity to major roadways as the exposure metric, there was a negative association with increasing distance from a maternal residence to the nearest major roadway (Odds Ratio (OR) = 0.96; 95% CI = 0.94–0.97) per 1000 m); however, once adjusted for covariates this effect was no longer significant (AOR = 0.98; 95% CI = 0.96–1.00). There was no association with distance weighted traffic density (DWTD). ^ This project is the first to look at SGA and combustion pollutants in the Southern United States with three different exposure metrics. Although there was no evidence of associations found between SGA and the air pollutants mentioned in these studies, the results contribute to the body of literature assessing maternal exposure to ambient air pollution and adverse birth outcomes. ^