All Stressors Are Not Equal: The Salience of Racial Discrimination and Appraisal for Blood Pressure in African American Women.

OBJECTIVE: Psychosocial stress is a major predictor of chronic disease among African American (AA) women. Stress is a process involving exposure, appraisal of threat, coping, and psychobiologic adaptation. However, many studies focus on the frequency of stress events and/or coping; few explicitly study stress events and their appraisals; and AA women experience high levels of racial discrimination, a well-known form of social identity threat (i.e., negative experiences due to judgment based on identity). Stressors related to social identity threat may be differentially appraised and associated with divergent physiologic outcomes. This study examined the differences in the frequency and stressfulness associated with general stressors and racial discrimination in relation to blood pressure (BP) among AA women. METHODS: Multivariable regression was used on cross-sectional data from 208 middle-aged AA women residing in the San Francisco Bay Area. RESULTS: AA women reported less frequency of racial discrimination compared with general stressors, but were more likely to appraise racial discrimination events as stressful. Racial discrimination stressfulness was more strongly associated with systolic BP (SBP) than the number of racial discrimination events. There was a U-shaped association between racial discrimination stress and SBP, with those reporting "none" and "high/very high" distress having the highest SBP ( b = 12.2 [2.7 to 21.8] and b = 15.7 [1.5-29.8], respectively, versus moderate stress). Conversely, those reporting "very low" general stressfulness had the lowest SBP ( b = -7.9 [-15.8 to -0.1], versus moderate stress). Diastolic BP followed a similar pattern, although results were nonsignificant. CONCLUSIONS: This study highlights the importance of stress appraisal measures and adds to the body of evidence documenting racial discrimination as a salient psychosocial stressor for AA women.

Genomic prediction with haplotype blocks in wheat.

Haplotype blocks might carry additional information compared to single SNPs and have therefore been suggested for use as independent variables in genomic prediction. Studies in different species resulted in more accurate predictions than with single SNPs in some traits but not in others. In addition, it remains unclear how the blocks should be built to obtain the greatest prediction accuracies. Our objective was to compare the results of genomic prediction with different types of haplotype blocks to prediction with single SNPs in 11 traits in winter wheat. We built haplotype blocks from marker data from 361 winter wheat lines based on linkage disequilibrium, fixed SNP numbers, fixed lengths in cM and with the R package HaploBlocker. We used these blocks together with data from single-year field trials in a cross-validation study for predictions with RR-BLUP, an alternative method (RMLA) that allows for heterogeneous marker variances, and GBLUP performed with the software GVCHAP. The greatest prediction accuracies for resistance scores for B. graminis, P. triticina, and F. graminearum were obtained with LD-based haplotype blocks while blocks with fixed marker numbers and fixed lengths in cM resulted in the greatest prediction accuracies for plant height. Prediction accuracies of haplotype blocks built with HaploBlocker were greater than those of the other methods for protein concentration and resistances scores for S. tritici, B. graminis, and P. striiformis. We hypothesize that the trait-dependence is caused by properties of the haplotype blocks that have overlapping and contrasting effects on the prediction accuracy. While they might be able to capture local epistatic effects and to detect ancestral relationships better than single SNPs, prediction accuracy might be reduced by unfavorable characteristics of the design matrices in the models that are due to their multi-allelic nature.

Differential associations between everyday versus institution-specific racial discrimination, self-reported health, and allostatic load among black women: implications for clinical assessment and epidemiologic studies.

PURPOSE: Black women have the highest estimated allostatic load (AL). AL and self-perceived health are strong health predictors and have been linked to racial discrimination. Research suggests that everyday and institution-specific racial discrimination may predict different AL and self-reported health (SRH) outcomes. Furthermore, discrepancies between AL and self-perceived health could widen disparities. We estimated associations between everyday versus institution-specific racial discrimination with AL and SRH. METHODS: Data are from a San Francisco Bay Area community sample of 208 black women aged 30-50 years. Participation involved a questionnaire, self-interview, blood draw, and anthropometric measurements. Adjusted generalized linear regression models estimated associations of racial discrimination with AL and SRH. RESULTS: After adjusting for age, socioeconomic position, and medication use, institution-specific discrimination was negatively associated with AL (i.e., better health), whereas everyday experiences showed no association. Those reporting very-high (vs. moderate) institution-specific discrimination had lower AL (ß = -1.31 [95% CI: -2.41, -0.20]; AL range: 0-15). No racial discrimination-SRH association was found. CONCLUSIONS: For black women, (1) institution-specific racial discrimination may be differentially embodied compared with everyday experiences and (2) institutional racism may contribute to physiologic stress-regulation regardless of self-perceived health status. Potential factors that may contribute to an inverse racial discrimination-AL association, and future research, are discussed.

Racial discrimination, educational attainment, and biological dysregulation among midlife African American women.

OBJECTIVE: To examine the association between self-reported racial discrimination and allostatic load, and whether the association differs by socioeconomic position. METHODS: We recruited a purposive cross-section of midlife (ages 30-50) African American women residing in four San Francisco Bay area counties (n = 208). Racial discrimination was measured using the Experience of Discrimination scale. Allostatic load was measured as a composite of 15 biomarkers assessing cardiometabolic, neuroendocrine, and inflammatory activity. We calculated four composite measures of allostatic load and three system-specific measures of biological dysregulation. Multivariable regression was used to examine associations, while adjusting for relevant confounders. RESULTS: In the high education group, reporting low (b = -1.09, P = .02, 95% CI = -1.99, -0.18) and very high (b = -1.88, P = .003, 95% CI = -3.11, -0.65) discrimination was associated with lower allostatic load (reference=moderate). Among those with lower education, reporting low (b = 2.05, P = .008, 95% CI = 0.55,3.56) discrimination was associated with higher allostatic load. Similar but less consistent associations were found for poverty status. Associations were similar for cardiometabolic functioning, but not for neuroendocrine or inflammatory activity. CONCLUSIONS: Racial discrimination may be an important predictor of cumulative physiologic dysregulation. Factors associated with educational attainment may mitigate this association for African American women and other groups experiencing chronic social stress.