Mechanisms of perceptual learning of depth discrimination in random dot stereograms.

Perceptual learning is a training induced improvement in performance. Mechanisms underlying the perceptual learning of depth discrimination in dynamic random dot stereograms were examined by assessing stereothresholds as a function of decorrelation. The inflection point of the decorrelation function was defined as the level of decorrelation corresponding to 1.4 times the threshold when decorrelation is 0%. In general, stereothresholds increased with increasing decorrelation. Following training, stereothresholds and standard errors of measurement decreased systematically for all tested decorrelation values. Post training decorrelation functions were reduced by a multiplicative constant (approximately 5), exhibiting changes in stereothresholds without changes in the inflection points. Disparity energy model simulations indicate that a post-training reduction in neuronal noise can sufficiently account for the perceptual learning effects. In two subjects, learning effects were retained over a period of six months, which may have application for training stereo deficient subjects.

Aminoacyl-tRNA synthetases: Probing the molecular basis of catalysis and discrimination

Aminoacyl-tRNA synthetases (RSs) are responsible for the essential connection of amino acids with trinucleotide sequences of tRNA's. The RS family constitutes two structurally dissimilar groups of proteins, class I and class II. Methionyl-tRNA synthetase (MetRS) and isoleucyl-tRNA synthetase (IleRS), both members of class I, were the focus of this work. Both enzymes are zinc-containing proteins; show a high degree of amino acid specificity; and edit activated noncognate amino acids, thereby ensuring the fidelity of the genetic code. The goals of this work were to further delineate the molecular basis of catalysis and discrimination in these enzymes by mapping active site geometries using high-resolution nuclear magnetic resonance spectroscopy (NMR).^ Internuclear distances obtained from transferred nuclear Overhauser effects were used to define the conformations of Mg($\alpha$,$\beta$-methylene)ATP bound to E. coli MetRS and E. coli IleRS in multiple complexes. Identical conformations were found for the bound ATP. Thus, the predicted structural homology between IleRS and MetRS is supported by consensus enzyme-bound nucleotide conformations. The conformation of the bound nucleotide is not sensitive to occupation of the amino acid site of MetRS or IleRS. Therefore, conformational changes known to occur in the synthetases upon ligand binding appear not to alter the bound conformation of the adenosine portion of the nucleotide. Nuclear Overhauser effects on the substrate amino acid L-selenomethionine were also used to evaluate the enzyme-bound conformation of the cognate amino acid. The amino acid assumes a conformation which is consistent with a proposed editing mechanism.^ The E. coli MetRS was shown to catalyze amino acid $\alpha$-proton exchange in the presence of deuterium oxide of all cognate amino acids. It is proposed that the enzyme-bound zinc coordinates the $\alpha$-carboxylate of the amino acid, rendering the $\alpha$-proton more acidic. An enzymic base is responsible for exchange of the $\alpha$-proton. This proposal suggests that the enzyme-bound zinc may have a role in amino acid discrimination in MetRS. However, the role of this exchange reaction in catalysis remains unknown. ^

Race and discourse analysis: Building a dialogue in health service research and health care settings

Using a framework for discourse analysis developed by Van Dijk, the investigator will pinpoint the pathological forms of discourse on race, defined as 'race talk' in three professional domains: health services research, public health provider organizations, and literature on multiculturalism. Attention will then turn to developing an analytical strategy for building more meaningful dialogue on race. The retrieval of potential resources for dialogue will be drawn from the third domain. Analysis will focus on enhancing the prospects of converting 'race talk' into dialogue. This will be accomplished by characterizing the normative preconditions as formal procedural requirements for dialogue and then supplementing these conditions with others related specifically to race. From here, the practical implications of combining procedural requirements and resources in each of the domains will be considered. Finally, the author will attempt to determine how these selected resources might be employed to transform 'race talk' in practice and lay the groundwork for a dialogue of understanding. ^

The impact of host immunity on oscillating rates of syphilis when gender and race are considered

The rates of syphilis in the United States have increased since the all time low in 2000. In 2003, the rates of syphilis in the United States were 2.5 cases per 100,000. There were 178 reported cases of primary and secondary syphilis (8.9 cases per 100,000) in Houston, Texas, which was a 58.9% increase from 2002. While syphilis can be completely treated now, unlike in times past, it is still a public health concern. The purpose of this study is to examine the possibility of modeling the impact of an immune response in primary and secondary syphilis in 63 major cities across the United States, stratified by gender and racial-ethnic groups. A Fourier analysis will be performed by SAS. Subsequently, this study will compare the results to a similar study of syphilis in 68 US cities, that focused on immune response, however, did not stratified by race and gender. This study will help determine if the oscillating rates of syphilis are due to biological factors of the disease or to behavioral changes in the population. This study will use surveillance data from 63 major cities across the United States. The data will be provided by the Centers of Disease Control. Ultimately, this study will expand the knowledge of the effect of immunity on endemics.^

The influence of socioeconomic status on the relationship between diabetes and amputations: A systematic review of the literature

This paper synthesizes the current knowledge available regarding the impact of socioeconomic status on diabetes and amputations. In September 2009, searches in the OVID Medline and PubMed databases were performed using keywords associated with race/ethnicity, educational level, insurance status, veteran status, low income, diabetes, and lower extremity amputation. Articles published between 1996 and the search date were used. The pertinent articles were analyzed, summarized, and synthesized. ^ The majority of the articles agreed that African American, American Indian, and Latino minorities experience significantly higher rates of diabetes-related lower extremity amputation (LEA) when compared to whites. Few articles suggested that the disparity experienced by minorities and others of low SES was due to biology; most articles link it to a combination of lower income, lower educational attainment, uninsured or underinsured status, and a greater prevalence of detrimental health behaviors such as smoking. These, in turn, are linked to decreased knowledge of self-care, delayed health care seeking, delayed diagnoses and treatment, discrimination, and low quality health care. Interventions focused on patient education, established regimens of treatment, foot care, and control of diabetes have been shown to be effective, although none have lowered the rate of diabetes-related LEA to rates found in the general population.^

Exploring race/ethnicity as a risk factor for mortality in newborns following congenital heart surgery at a center of excellence

The purpose of this study was to determine if race/ethnicity was a significant risk factor for hospital mortality in children following congenital heart surgery in a contemporary sample of newborns with congenital heart disease. Unlike previous studies that utilized administrative databases, this study utilized clinical data collected at the point of care to examine racial/ethnic outcome differences in the context of the patients' clinical condition and their overall perioperative experience. A retrospective cohort design was used. The study sample consisted of 316 newborns (<31 days of age) who underwent congenital heart surgery between January 2007 through December 2009. A multivariate logistic regression model was used to determine the impact of race/ethnicity, insurance status, presence of a spatial anomaly, prenatal diagnosis, postoperative sepsis, cardiac arrest, respiratory failure, unplanned reoperation, and total length of stay in the intensive care unit on outcomes following congenital heart surgery in newborns. The study findings showed that the strongest predictors of hospital mortality following congenital heart surgery in this cohort were postoperative cardiac arrest, postoperative respiratory failure, having a spatial anomaly, and total ICU LOS. Race/ethnicity and insurance status were not significant risk factors. The institution where this study was conducted is designated as a center of excellence for congenital heart disease. These centers have state-of-the-art facilities, extensive experience in caring for children with congenital heart disease, and superior outcomes. This study suggests that optimal care delivery for newborns requiring congenital heart surgery at a center of excellence portends exceptional outcomes and this benefit is conferred upon the entire patient population despite the race/ethnicity of the patients. From a public health and health services view, this study also contributes to the overall body of knowledge on racial/ethnic disparities in children with congenital heart defects and puts forward the possibility of a relationship between quality of care and racial/ethnic disparities. Further study is required to examine the impact of race/ethnicity on the long-term outcomes of these children as they encounter the disparate components of the health care delivery system. There is also opportunity to study the role of race/ethnicity on the hospital morbidity in these patients considering current expectations for hospital survival are very high, and much of the current focus for quality improvement rests in minimizing the development of patient morbidities.^

Measurement of isotopic uranium in water for compliance monitoring by liquid scintillation counting with alpha/beta discrimination

A simple and inexpensive method is described for analysis of uranium (U) activity and mass in water by liquid scintillation counting using $\alpha$/$\beta$ discrimination. This method appears to offer a solution to the need for an inexpensive protocol for monitoring U activity and mass simultaneously and an alternative to the potential inaccuracy involved when depending on the mass-to-activity conversion factor or activity screen.^ U is extracted virtually quantitatively into 20 ml extractive scintillator from a 1-$\ell$ aliquot of water acidified to less than pH 2. After phase separation, the sample is counted for a 20-minute screening count with a minimum detection level of 0.27 pCi $\ell\sp{-1}$. $\alpha$-particle emissions from the extracted U are counted with close to 100% efficiency with a Beckman LS6000 LL liquid scintillation counter equipped with pulse-shape discrimination electronics. Samples with activities higher than 10 pCi $\ell\sp-1$ are recounted for 500-1000 minutes for isotopic analysis. Isotopic analysis uses events that are automatically stored in spectral files and transferred to a computer during assay. The data can be transferred to a commercially available spreadsheet and retrieved for examination or data manipulation. Values for three readily observable spectral features can be rapidly identified by data examination and substituted into a simple formula to obtain $\sp{234}$U/$\sp{238}$U ratio for most samples. U mass is calculated by substituting the isotopic ratio value into a simple equation.^ The utility of this method for the proposed compliance monitoring of U in public drinking water supplies was field tested with a survey of drinking water from Texas supplies that had previously been known to contain elevated levels of gross $\alpha$ activity. U concentrations in 32 samples from 27 drinking water supplies ranged from 0.26 to 65.5 pCi $\ell\sp{-1}$, with seven samples exceeding the proposed Maximum Contaminant Level of 20 $\mu$g $\ell\sp{-1}$. Four exceeded the proposed activity screening level of 30 pCi $\ell\sp{-1}$. Isotopic ratios ranged from 0.87 to 41.8, while one sample contained $\sp{234}$U activity of 34.6 pCi $\ell\sp{-1}$ in the complete absence of its parent, $\sp{238}$U. U mass in the samples with elevated activity ranged from 0.0 to 103 $\mu$g $\ell\sp{-1}$. A limited test of screening surface and groundwaters for contamination by U from waste sites and natural processes was also successful. ^

AN ANALYSIS OF THE RELATIVE INFLUENCE OF RACE, INCOME, EDUCATION, AND FOOD STAMP PROGRAM PARTICIPATION/NONPARTICIPATION ON THE FOOD AND NUTRIENT CONSUMPTION OF A NORTH FLORIDA URBAN CLINIC POPULATION IN CONJUNCTION WITH A SURVEY OF NUTRITION RELATED HABITS AND ATTITUDES

The relative influence of race, income, education, and Food Stamp Program participation/nonparticipation on the food and nutrient intake of 102 fecund women ages 18-45 years in a Florida urban clinic population was assessed using the technique of multiple regression analysis. Study subgroups were defined by race and Food Stamp Program participation status. Education was found to have the greatest influence on food and nutrient intake. Race was the next most influential factor followed in order by Food Stamp Program participation and income. The combined effect of the four independent variables explained no more than 19 percent of the variance for any of the food and nutrient intake variables. This would indicate that a more complex model of influences is needed if variations in food and nutrient intake are to be fully explained.^ A socioeconomic questionnaire was administered to investigate other factors of influence. The influence of the mother, frequency and type of restaurant dining, and perceptions of food intake and weight were found to be factors deserving further study.^ Dietary data were collected using the 24-hour recall and food frequency checklist. Descriptive dietary findings indicated that iron and calcium were nutrients where adequacy was of concern for all study subgroups. White Food Stamp Program participants had the greatest number of mean nutrient intake values falling below the 1980 Recommended Dietary Allowances (RDAs). When Food Stamp Program participants were contrasted to nonparticipants, mean intakes of six nutrients (kilocalories, calcium, iron, vitamin A, thiamin, and riboflavin) were below the 1980 RDA compared to five mean nutrient intakes (kilocalories, calcium, iron, thiamin and riboflavin) for the nonparticipants. Use of the Index of Nutritional Quality (INQ), however, revealed that the quality of the diet of Food Stamp Program participants per 1000 kilocalories was adequate with exception of calcium and iron. Intakes of these nutrients were also not adequate on a 1000 kilocalorie basis for the nonparticipant group. When mean nutrient intakes of the groups were compared using Student's t-test oleicacid intake was the only significant difference found. Being a nonparticipant in the Food Stamp Program was found to be associated with more frequent consumption of cookies, sweet rolls, doughnuts, and honey. The findings of this study contradict the negative image of the Food Stamp Program participant and emphasize the importance of education. ^

A systematic review of the methods used to assess race and racial disparities in uterine fibroid research

Context: Black women are reported to have a higher prevalence of uterine fibroids, and a threefold higher incidence rate and relative risk for clinical uterine fibroid development as compared to women of other races. Uterine fibroid research has reported that black women experience greater uterine fibroid morbidity and disproportionate uterine fibroid disease burden. With increased interest in understanding uterine fibroid development, and race being a critical component of uterine fibroid assessment, it is imperative that the methods used to determine the race of research participants is defined and the operational definition of the use of race as a variable is reported for methodological guidance, and to enable the research community to compare statistical data and replicate studies. ^ Objectives: To systematically review and evaluate the methods used to assess race and racial disparities in uterine fibroid research. ^ Data Sources: Databases searched for this review include: OVID Medline, NML PubMed, Ebscohost Cumulative Index to Nursing and Allied Health Plus with Full Text, and Elsevier Scopus. ^ Review Methods: Articles published in English were retrieved from data sources between January 2011 and March 2011. Broad search terms, uterine fibroids and race, were employed to retrieve a comprehensive list of citations for review screening. The initial database yield included 947 articles, after duplicate extraction 485 articles remained. In addition, 771 bibliographic citations were reviewed to identify additional articles not found through the primary database search, of which 17 new articles were included. In the first screening, 502 titles and abstracts were screened against eligibility questions to determine citations of exclusion and to retrieve full text articles for review. In the second screening, 197 full texted articles were screened against eligibility questions to determine whether or not they met full inclusion/exclusion criteria. ^ Results: 100 articles met inclusion criteria and were used in the results of this systematic review. The evidence suggested that black women have a higher prevalence of uterine fibroids when compared to white women. None of the 14 studies reporting data on prevalence reported an operational definition or conceptual framework for the use of race. There were a limited number of studies reporting on the prevalence of risk factors among racial subgroups. Of the 3 studies, 2 studies reported prevalence of risk factors lower for black women than other races, which was contrary to hypothesis. And, of the three studies reporting on prevalence of risk factors among racial subgroups, none of them reported a conceptual framework for the use of race. ^ Conclusion: In the 100 uterine fibroid studies included in this review over half, 66%, reported a specific objective to assess and recruit study participants based upon their race and/or ethnicity, but most, 51%, failed to report a method of determining the actual race of the participants, and far fewer, 4% (only four South American studies), reported a conceptual framework and/or operational definition of race as a variable. However, most, 95%, of all studies reported race-based health outcomes. The inadequate methodological guidance on the use of race in uterine fibroid studies, purporting to assess race and racial disparities, may be a primary reason that uterine fibroid research continues to report racial disparities, but fails to understand the high prevalence and increased exposures among African-American women. A standardized method of assessing race throughout uterine fibroid research would appear to be helpful in elucidating what race is actually measuring, and the risk of exposures for that measurement. ^

Impact of donor-recipient gender and race mismatching on patient survival in patients with end-stage liver diseases undergoing liver transplantation

Background. End-stage liver disease (ESLD) is an irreversible condition that leads to the imminent complete failure of the liver. Orthotopic liver transplantation (OLT) has been well accepted as the best curative option for patients with ESLD. Despite the progress in liver transplantation, the major limitation nowadays is the discrepancy between donor supply and organ demand. In an effort to alleviate this situation, mismatched donor and recipient gender or race livers are being used. However, the simultaneous impact of donor and recipient gender and race mismatching on patient survival after OLT remains unclear and relatively challenging to surgeons. ^ Objective. To examine the impact of donor and recipient gender and race mismatching on patient survival after OLT using the United Network for Organ Sharing (UNOS) database. ^ Methods. A total of 40,644 recipients who underwent OLT between 2002 and 2011 were included. Kaplan-Meier survival curves and the log-rank tests were used to compare the survival rates among different donor-recipient gender and race combinations. Univariate Cox regression analysis was used to assess the association of donor-recipient gender and race mismatching with patient survival after OLT. Multivariable Cox regression analysis was used to model the simultaneous impact of donor-recipient gender and race mismatching on patient survival after OLT adjusting for a list of other risk factors. Multivariable Cox regression analysis stratifying on recipient hepatitis C virus (HCV) status was also conducted to identify the variables that were differentially associated with patient survival in HCV + and HCV − recipients. ^ Results. In the univariate analysis, compared to male donors to male recipients, female donors to male recipients had a higher risk of patient mortality (HR, 1.122; 95% CI, 1.065–1.183), while in the multivariable analysis, male donors to female recipients experienced an increased mortality rates (adjusted HR, 1.114; 95% CI, 1.048–1.184). Compared to white donors to white recipients, Hispanic donors to black recipients had a higher risk of patient mortality (HR, 1.527; 95% CI, 1.293–1.804) in the univariate analysis, and similar result (adjusted HR, 1.553; 95% CI, 1.314–1.836) was noted in multivariable analysis. After the stratification on recipient HCV status in the multivariable analysis, HCV + mismatched recipients appeared to be at greater risk of mortality than HCV − mismatched recipients. Female donors to female HCV − recipients (adjusted HR, 0.843; 95% CI, 0.769–0.923), and Hispanic HCV + recipients receiving livers from black donors (adjusted HR, 0.758; 95% CI, 0.598–0.960) had a protective effect on patient survival after OLT. ^ Conclusion. Donor-recipient gender and race mismatching adversely affect patient survival after OLT, both independently and after the adjustment for other risk factors. Female recipient HCV status is an important effect modifier in the association between donor-recipient gender combination and patient survival.^

Attitudes of health-care workers toward pregnant, HIV -positive women

The management of HIV infection with antiretroviral drugs has succeeded in increasing survival rates, but the subject of pregnancy in HIV-positive women continues to garner debate. Discrimination and stigma have been identified as barriers to health care, suggesting that women with HIV may be disinclined to seek prenatal care if health-care workers exhibit negative attitudes toward the women's pregnancies. To optimize prenatal and medical care for women with HIV infection, it is important to understand the general social conditions and cultural context in which these women have children. Goffman's treatise on stigma, Foucault's discussion of the knowledge/power matrix, and Bandura's Social Cognitive Theory offer theoretical perspectives by which we can evaluate the gender, race, and class issues that are inherent in pregnancy decision-making for women with HIV infection. It is also necessary to evaluate prevailing attitudes on childbearing toward HIV-positive women and to review the historical background of prejudice in which HIV-positive women make decisions regarding childbearing. ^ This qualitative study used a survey instrument and one-on-one interviews with HIV-infected women to elicit their perceptions of how they were treated by care providers when they became pregnant. It also included interviews with health-care workers to determine what their feelings are about pregnancy within the context of HIV infection. Results of the ethnographic inquiry reveal that most of the women had negative experiences at some point during a pregnancy, but that the situation improved when they sought care from a provider who was familiar with HIV infection. The health-care providers interviewed were firm in their belief that HIV-positive women deserved optimal care and treated the women with respect, but these are individuals who are also experts in providing care to HIV-positive patients. The question remains as to what kind of care HIV-positive women are receiving generally and what types of attitudes they are being subjected to if they see less experienced providers. Further research is also needed to determine whether HIV-positive women from a broader ethnic representation and higher socioeconomic status experience similar negative attitudes. ^