The Brain Metabolome Is Modified by Obesity in a Sex-Dependent Manner.

Obesity is linked to cognitive decline and metabolic dysregulation in the brain, yet the role of sex is relatively unexplored. We sought to explore the effects of obesity and sex on the brain metabolome. In male and female ob/ob and wild-type mice, we assessed whole brain untargeted metabolomics by liquid chromatography-mass spectrometry, behavior by open field test, and cognitive function by Y-maze and Morris water maze. The metabolic profiles of ob/ob and wild-type mice differed in both sexes. There were more obesity-altered brain metabolites in males than females. Thirty-nine metabolites were unique to males, 15 were unique to females, and five were common to both sexes. Two of the common metabolites were involved in nicotinamide adenine dinucleotide homeostasis. A key feature of the metabolites identified in males was an increase in free fatty acids. In females, a unique feature was the presence of the neuro-modulatory metabolites 2-linoleoyl glycerol and taurine. The behavioral effects of obesity were only seen in females. These results demonstrate that most impacts of obesity on the brain metabolomic profile are sex-specific. Our work has implications for understanding the role of obesity in brain metabolism and the differential contribution of obesity to cognitive decline in males and females.

Single nuclei transcriptomics in diabetic mice reveals altered brain hippocampal endothelial cell function, permeability, and behavior.

Type 2 diabetes mellitus (T2DM) is a metabolic disorder with cerebrovascular and cardiovascular sequelae. Yet, a clear pattern of gene dysregulation by T2DM in dementia has yet to be defined. We used single nuclei RNA sequencing technology to profile the transcriptome of endothelial cells (EC) from anatomically defined hippocampus of db/db mice to identify differentially expressed (DE) genes, gene pathways and networks, predicted regulating transcription factors, and targets of DE long noncoding RNAs. We also applied gadolinium (Gd) enhanced magnetic resonance imaging (MRI) to assess blood brain barrier (BBB) permeability, and functionally assessed cognitive behavior. The murine gene expression profiles were then integrated with those of persons with Alzheimer's disease (AD) and vascular dementia (VaD). We reveal that the transcriptome of the diabetic hippocampal murine brain endothelium differs substantially from control wild types with molecular changes characterized by differential RNA coding and noncoding pathways enriched for EC signaling and for endothelial functions for neuroinflammation, endothelial barrier disruption, and neurodegeneration. Gd enhanced structural brain MRI linked endothelial molecular alterations to BBB dysfunction by neuroimaging. Integrated multiomics of hippocampal endothelial gene dysregulation associated with impairments in cognitive adaptive capacity. In addition, the diabetic transcriptome significantly and positively correlated with that of persons with AD and VaD. Taken together, our results from comprehensive, multilevel, integrated, single nuclei transcriptomics support the hypothesis of T2DM-mediated neuroinflammation and endothelial cell and barrier disruption as key mechanisms in cognitive decline in T2DM, thereby suggesting potential endothelial-specific molecular therapeutic targets.

Sex Modifies the Impact of Type 2 Diabetes Mellitus on the Murine Whole Brain Metabolome.

Type 2 diabetes mellitus (T2DM) leads to the development of cardiovascular diseases, cognitive impairment, and dementia. There are sex differences in the presentation of T2DM and its associated complications. We sought to determine the impact of sex and T2DM on the brain metabolome to gain insights into the underlying mechanisms of T2DM-associated cognitive complications. Untargeted metabolomic analysis was performed, using liquid chromatography-mass spectrometry, on whole brain tissue from adult male and female db/db mice (a T2DM model) compared to wild-type (WT) C57Bl6/J mice. Regardless of sex, T2DM increased free fatty acids and decreased acylcarnitines in the brain. Sex impacted the number (103 versus 65 in males and females, respectively), and types of metabolites shifted by T2DM. Many choline-containing phospholipids were decreased by T2DM in males. Female-specific T2DM effects included changes in neuromodulatory metabolites (γ-aminobutyric acid, 2-linoleoyl glycerol, N-methylaspartic acid, and taurine). Further, there were more significantly different metabolites between sexes in the T2DM condition as compared to the WT controls (54 vs. 15 in T2DM and WT, respectively). T2DM alters the murine brain metabolome in both sex-independent and sex-dependent manners. This work extends our understanding of brain metabolic sex differences in T2DM, cognitive implications, and potential sex-specific metabolic therapeutic targets.

Sex-Specific Response of the Brain Free Oxylipin Profile to Soluble Epoxide Hydrolase Inhibition.

Oxylipins are the oxidation products of polyunsaturated fatty acids and have been implicated in neurodegenerative disorders, including dementia. Soluble epoxide hydrolase (sEH) converts epoxy-fatty acids to their corresponding diols, is found in the brain, and its inhibition is a treatment target for dementia. In this study, male and female C57Bl/6J mice were treated with an sEH inhibitor (sEHI), trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB), for 12 weeks to comprehensively study the effect of sEH inhibition on the brain oxylipin profile, and modulation by sex. Ultra-high-performance liquid chromatography-tandem mass spectrometry was used to measure the profile of 53 free oxylipins in the brain. More oxylipins were modified by the inhibitor in males than in females (19 versus 3, respectively) and favored a more neuroprotective profile. Most were downstream of lipoxygenase and cytochrome p450 in males, and cyclooxygenase and lipoxygenase in females. The inhibitor-associated oxylipin changes were unrelated to serum insulin, glucose, cholesterol, or female estrous cycle. The inhibitor affected behavior and cognitive function as measured by open field and Y-maze tests in males, but not females. These findings are novel and important to our understanding of sexual dimorphism in the brain's response to sEHI and may help inform sex-specific treatment targets.

A high sucrose diet modifies brain oxylipins in a sex-dependent manner.

BACKGROUND: Oxylipins have been implicated in many biological processes and diseases. Dysregulation of cerebral lipid homeostasis and altered lipid metabolites have been associated with the onset and progression of dementia. Although most dietary interventions have focused on modulation of dietary fats, the impact of a high sucrose diet on the brain oxylipin profile is unknown. METHODS: Male and female C57BL/6J mice were fed a high sucrose diet (HSD, 34%) in comparison to a control low sucrose diet (LSD, 12%) for 12 weeks beginning at 20 weeks of age. The profile of 53 free oxylipins was then measured in brain by ultra-high performance liquid chromatography tandem mass spectrometry. Serum glucose and insulin were measured enzymatically. We first assessed whether there were any effects of the diet on the brain oxylipin profile, then assessed for sex differences. RESULTS: There were no differences in fasting serum glucose between the sexes for mice fed a HSD or in fasting serum insulin levels for mice on either diet. The HSD altered the brain oxylipin profile in both sexes in distinctly different patterns: there was a reduction in three oxylipins (by 47-61%) and an increase in one oxylipin (16%) all downstream of lipoxygenase enzymes in males and a reduction in eight oxylipins (by 14-94%) mostly downstream of cyclooxygenase activity in females. 9-oxo-ODE and 6-trans-LTB4 were most influential in the separation of the oxylipin profiles by diet in male mice, whereas 5-HEPE and 12-HEPE were most influential in the separation by diet in female mice. Oxylipins 9­hydroxy-eicosatetraenoic acid (HETE), 11-HETE, and 15-HETE were higher in the brains of females, regardless of diet. CONCLUSION: A HSD substantially changes brain oxylipins in a distinctly sexually dimorphic manner. Results are discussed in terms of potential mechanisms and links to metabolic disease. Sex and diet effects on brain oxylipin composition may provide future targets for the management of neuroinflammatory diseases, such as dementia.

Sex-Dependent Molecular Mechanisms of Lipotoxic Injury in Brain Microvasculature: Implications for Dementia.

Cardiovascular risk factors and biologic sex play a role in vascular dementia which is characterized by progressive reduction in cognitive function and memory. Yet, we lack understanding about the role sex plays in the molecular mechanisms whereby lipid stress contributes to cognitive decline. Five-week-old low-density lipoprotein deficient (LDL-R -/-) male and female mice and C57BL/6J wild types (WT) were fed a control or Western Diet for 8 weeks. Differential expression of protein coding and non-protein coding genes (DEG) were determined in laser captured hippocampal microvessels using genome-wide microarray, followed by bioinformatic analysis of gene networks, pathways, transcription factors and sex/gender-based analysis (SGBA). Cognitive function was assessed by Y-maze. Bioinformatic analysis revealed more DEGs in females (2412) compared to males (1972). Hierarchical clusters revealed distinctly different sex-specific gene expression profiles irrespective of diet and genotype. There were also fewer and different biologic responses in males compared to females, as well as different cellular pathways and gene networks (favoring greater neuroprotection in females), together with sex-specific transcription factors and non-protein coding RNAs. Hyperlipidemic stress also resulted in less severe cognitive dysfunction in females. This sex-specific pattern of differential hippocampal microvascular RNA expression might provide therapeutic targets for dementia in males and females.

Lipotoxic Injury Differentially Regulates Brain Microvascular Gene Expression in Male Mice.

The Western diet (WD) and hyperlipidemia are risk factors for vascular disease, dementia, and cognitive impairment. However, the molecular mechanisms are poorly understood. This pilot study investigated the genomic pathways by which the WD and hyperlipidemia regulate gene expression in brain microvessels. Five-week-old C57BL/6J wild type (WT) control and low-density lipoprotein receptor deficient (LDL-R-/-) male mice were fed the WD for eight weeks. Differential gene expression, gene networks and pathways, transcription factors, and non-protein coding RNAs were evaluated by a genome-wide microarray and bioinformatics analysis of laser-captured hippocampal microvessels. The WD resulted in the differential expression of 1972 genes. Much of the differentially expressed gene (DEG) was attributable to the differential regulation of cell signaling proteins and their transcription factors, approximately 4% was attributable to the differential expression of miRNAs, and 10% was due to other non-protein coding RNAs, primarily long non-coding RNAs (lncRNAs) and small nucleolar RNAs (snoRNAs) not previously described to be modified by the WD. Lipotoxic injury resulted in complex and multilevel molecular regulation of the hippocampal microvasculature involving transcriptional and post-transcriptional regulation and may provide a molecular basis for a better understanding of hyperlipidemia-associated dementia risk.

Barriers to Career Flexibility in Academic Medicine: A Qualitative Analysis of Reasons for the Underutilization of Family-Friendly Policies, and Implications for Institutional Change and Department Chair Leadership.

PURPOSE: Academic medical and biomedical professionals need workplace flexibility to manage the demands of work and family roles and meet their commitments to both, but often fail to use the very programs and benefits that provide flexibility. This study investigated the reasons for faculty underutilization of work-life programs. METHOD: As part of a National Institutes of Health-funded study, in 2010 the authors investigated attitudes of clinical and/or research biomedical faculty at the University of California, Davis, toward work-life policies, and the rationale behind their individual decisions regarding use of flexibility policies. The analysis used verbatim responses from 213 of 472 faculty (448 unstructured comments) to a series of open-ended survey questions. Questions elicited faculty members' self-reports of policy use, attitudes, and evaluations of the policies, and their perceptions of barriers that limited full benefit utilization. Data were coded and analyzed using a grounded theory approach. RESULTS: Faculty described how their utilization of workplace flexibility benefits was inhibited by organizational influences: the absence of reliable information about program eligibility and benefits, workplace norms and cultures that stigmatized program participation, influence of uninformed/unsupportive department heads, and concerns about how participation might burden coworkers, damage collegial relationships, or adversely affect workflow and grant funding. CONCLUSIONS: Understanding underuse of work-life programs is essential to maximize employee productivity and satisfaction, minimize turnover, and provide equal opportunities for career advancement to all faculty. The findings are discussed in relation to specific policy recommendations, implications for institutional change, and department chair leadership.

Evaluating a Medical School's Climate for Women's Success: Outcomes for Faculty Recruitment, Retention, and Promotion.

OBJECTIVE: Women are under-represented in academia. Causative factors include challenges of career-family integration. We evaluated factors reflecting institutional culture (promotion, retention, hiring, and biasing language in promotion letters) as part of an intervention to help shift culture and raise awareness of flexibility policies at the University of California, Davis (UCD). MATERIALS AND METHODS: Data on faculty use of family-friendly policies were obtained at baseline, and surveys for policy awareness were conducted pre(2010)/post(2013) an NIH-funded study educational intervention. Data on hires, separations, and promotions were obtained pre(2007-2009, 2234 person-year data points)/post(2010-2012, 2384 person-year data points) intervention and compared by logistic regression and for gender differences. Department promotion letters (53) were also analyzed for biasing language. RESULTS: Policy use was overall low, highest for female assistant professors, and for maternity leave. Awareness significantly increased for all policies postintervention. Promotions decreased, likely because of increases in advancement deferrals or tenure clock extensions. Pre/postintervention, female and male hires were near parity for assistant professors, but female hires were substantially lower than males for associate (54% less likely, p = 0.03) and full professors (70% less likely, p = 0.002). Once hired, women were no more likely to separate than men. Fewer associate/full professors separated than assistant professors (p = 0.002, p < 0.001, respectively), regardless of gender. Language in promotion letters was not gender biased. CONCLUSIONS: We demonstrate a shift at UCD toward a culture of work-life flexibility, an environment in which letters of recommendation show very few biased descriptions, and in which assistant professor hiring is gender equitable. At the same time, a decrease in number of faculty members applying for promotion and an imbalance of men over women at senior hires independent of policy awareness may challenge the assumption that family-friendly policies, while promoting flexibility, also have a positive impact on professional advancement.

Outcomes of a Clinic-Based Educational Intervention for Cardiovascular Disease Prevention by Race, Ethnicity, and Urban/Rural Status.

BACKGROUND AND PURPOSE: Heart disease is the leading killer of women and remains poorly recognized in high-risk groups. We assessed baseline knowledge gaps and efficacy of a survey-based educational intervention. METHODS: Four hundred seventy-two women in clinical settings completed pre-/post-surveys for knowledge of: heart disease as the leading killer, risk factors (general and personal levels), heart attack/stroke symptoms, and taking appropriate emergency action. They received a clinic-based educational intervention delivered by healthcare professionals in the course of their clinical care. Change score analyses tested pre-/post-differences in knowledge after the educational intervention, comparing proportions by race, ethnicity, and urban/nonurban status. RESULTS: Knowledge and awareness was low in all groups, especially for American Indian women (p < 0.05). Awareness was overall highest for heart disease as the leading killer, but it was the lowest for taking appropriate action (13% of Hispanic, 13% of American Indian, 29% of African American, and 18% of nonurban women; p < 0.05). For all women, knowledge of the major risk factors was low (58%) as was knowledge of their personal levels for risk factors (73% awareness for hypertension, 54% for cholesterol, and 50% for diabetes). The intervention was effective (% knowledge gain) in all groups of women, particularly for raising awareness of: (1) heart disease as the leading killer in American Indian (25%), Hispanic (18%), and nonurban (15%) women; (2) taking appropriate action for American Indian (80%), African American (64%), non-Hispanic (55%), and urban (56%) women; (3) heart disease risk factors for Hispanic (56%) and American Indian (47%) women; and (4) heart disease and stroke symptoms in American Indian women (54% and 25%, respectively). CONCLUSIONS: Significant knowledge gaps persist for heart disease in high-risk women, suggesting that these gaps and groups should be targeted by educational programs. We specify areas of need, and we demonstrate efficacy of a clinic-based educational intervention that can be of utility to busy healthcare professionals.

Lipotoxic brain microvascular injury is mediated by activating transcription factor 3-dependent inflammatory and oxidative stress pathways.

Dysfunction of the cerebrovasculature plays an important role in vascular cognitive impairment (VCI). Lipotoxic injury of the systemic endothelium in response to hydrolyzed triglyceride-rich lipoproteins (TGRLs; TGRL lipolysis products) or a high-fat Western diet (WD) suggests similar mechanisms may be present in brain microvascular endothelium. We investigated the hypothesis that TGRL lipolysis products cause lipotoxic injury to brain microvascular endothelium by generating increased mitochondrial superoxide radical generation, upregulation of activating transcription factor 3 (ATF3)-dependent inflammatory pathways, and activation of cellular oxidative stress and apoptotic pathways. Human brain microvascular endothelial cells were treated with human TGRL lipolysis products that induced intracellular lipid droplet formation, mitochondrial superoxide generation, ATF3-dependent transcription of proinflammatory, stress response, and oxidative stress genes, as well as activation of proapoptotic cascades. Male apoE knockout mice were fed a high-fat/high-cholesterol WD for 2 months, and brain microvessels were isolated by laser capture microdissection. ATF3 gene transcription was elevated 8-fold in the hippocampus and cerebellar brain region of the WD-fed animals compared with chow-fed control animals. The microvascular injury phenotypes observed in vitro and in vivo were similar. ATF3 plays an important role in mediating brain microvascular responses to acute and chronic lipotoxic injury and may be an important preventative and therapeutic target for endothelial dysfunction in VCI.

Inflammation and Cardiometabolic Risk in African American Women Is Reduced by a Pilot Community-Based Educational Intervention.

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of death for women, and African Americans have higher rates of CVD mortality than do other racio/ethnic groups. Women in community settings can benefit from preventive interventions, yet few investigations of successful programs have been conducted and evaluated in high-risk women, especially for metabolic syndrome. The purpose of our study was to pilot and assess the effectiveness of a 4-month pre-/post-CVD preventive educational intervention in improving knowledge, clinical risk profiles, adoption of heart-healthy lifestyles, inflammatory burden, and cardiometabolic risk in African American women in local communities. METHODS: Forty-two African American women (mean age 59 years) enrolled in the 4-month educational Cardiovascular Disease Preventive Intervention Program in Sacramento, CA, in 2010. Participants completed knowledge-based surveys pre-/postintervention, provided clinical measures (weight, waist circumference, body mass index (BMI), blood pressure and blood samples for analysis of fasting glucose and lipids, and inflammatory markers: tumor necrosis factor (TNF)-α±, high-sensitivity C-reactive protein (hs-CRP), and interleukin (IL)-12. RESULTS: The CVD risk profile of participants confirmed a high-risk cohort. Postintervention (n=31), there were significant (p<0.05) gains in knowledge for all symptoms of a heart attack and calling 911; improvements in clinical risk parameters, especially for waist circumference and low-density lipoprotein (LDL) cholesterol (p<0.05); and reductions in all the inflammatory markers assessed: TNF-α±by 16%, IL-12 by 20%, and hs-CRP by 26% (p<0.05). There was also a 60% reduction in the number of participants with metabolic syndrome (MetS) (p<0.05), driven primarily by reductions in triglycerides and glucose and a rise in high-density lipoprotein (HDL) cholesterol. CONCLUSIONS: We demonstrated the efficacy of a pilot community-based educational cardiovascular program in reducing cardiometabolic risk and inflammation in high-risk African American women. Our successful culturally appropriate and sustainable model could be implemented as part of comprehensive efforts to improve community-based health outcomes.

The Role of Compensation Criteria to Minimize Face-Time Bias and Support Faculty Career Flexibility: An Approach to Enhance Career Satisfaction in Academic Pathology.

Work-life balance is important to recruitment and retention of the younger generation of medical faculty, but medical school flexibility policies have not been fully effective. We have reported that our school's policies are underutilized due to faculty concerns about looking uncommitted to career or team. Since policies include leaves and accommodations that reduce physical presence, faculty may fear "face-time bias," which negatively affects evaluation of those not "seen" at work. Face-time bias is reported to negatively affect salary and career progress. We explored face-time bias on a leadership level and described development of compensation criteria intended to mitigate face-time bias, raise visibility, and reward commitment and contribution to team/group goals. Leaders from 6 partner departments participated in standardized interviews and group meetings. Ten compensation plans were analyzed, and published literature was reviewed. Leaders did not perceive face-time issues but saw team pressure and perception of availability as performance motivators. Compensation plans were multifactor productivity based with many quantifiable criteria; few addressed team contributions. Using these findings, novel compensation criteria were developed based on a published model to mitigate face-time bias associated with team perceptions. Criteria for organizational citizenship to raise visibility and reward group outcomes were included. We conclude that team pressure and perception of availability have the potential to lead to bias and may contribute to underuse of flexibility policies. Recognizing organizational citizenship and cooperative effort via specific criteria in a compensation plan may enhance a culture of flexibility. These novel criteria have been effective in one pilot department.

Do Family Responsibilities and a Clinical Versus Research Faculty Position Affect Satisfaction with Career and Work-Life Balance for Medical School Faculty?

BACKGROUND: Balancing career and family obligations poses challenges to medical school faculty and contributes to dissatisfaction and attrition from academics. We examined the relationship between family setting and responsibilities, rank, and career and work-life satisfaction for faculty in a large U.S. medical school. METHODS: Baseline faculty surveys were analyzed from the first year of a 4-year National Institutes of Health-funded study to evaluate awareness, knowledge, attitudes, and use of family friendly policies and career satisfaction. The study focus was on the impact of family responsibilities and characteristics of the faculty position (rank, clinical vs. nonclinical, and academic series) in multivariate comparisons between primary predictors and outcomes of interest. RESULTS: Both clinical and family responsibilities for children under 18 play a major and interacting role in satisfaction with career and work-life balance. Clinical faculty respondents without children at home reported significantly greater career satisfaction and better work-life balance than their nonclinical counterparts. Nonclinical faculty respondents with children reported greater satisfaction and better balance than counterparts without family responsibilities. However, the advantage in career satisfaction and work-life balance for clinical faculty respondents disappeared for those with responsibility for young children. No gender-based differences were noted in the results or across faculty rank for respondents; however, for women, reaching associate professor resulted in greater career satisfaction. CONCLUSION: This study suggests that both work-related factors and family responsibilities influence satisfaction with career and work-life balance, but the predictors appear to interact in complex and nuanced ways. Further research is needed to delineate more clearly these interactions and to explore other factors that may play important additional roles.

The Women in Medicine and Health Science program: an innovative initiative to support female faculty at the University of California Davis School of Medicine.

PROBLEM: Although more female physicians and scientists are choosing careers in academic medicine, women continue to be underrepresented as medical school faculty, particularly at the level of full professor and in leadership positions. Effective interventions to support women in academic medicine exist, but the nature and content of such programs varies widely. APPROACH: Women in medicine programs can play a critical role in supporting women's careers and can improve recruitment and retention of women by providing opportunities for networking, sponsorship, mentorship, and career development. The University of California Davis School of Medicine established the Women in Medicine and Health Science (WIMHS) program in 2000 to ensure the full participation and success of women in all roles within academic medicine. The authors describe the components and evolution of the WIMHS program. OUTCOMES: A steady increase in the number and percentage of female faculty and department chairs, as well as a relatively low departure rate for female faculty, strong and growing internal partnerships, and enthusiastic support from faculty and the school of medicine leadership, suggest that the WIMHS program has had a positive influence on recruitment and retention, career satisfaction, and institutional climate to provide a more inclusive and supportive culture for women. NEXT STEPS: Going forward, the WIMHS program will continue to advocate for broader institutional change to support female faculty, like creating an on-site child care program. Other institutions seeking to address the challenges facing female faculty may consider using the WIMHS program as a model to guide their efforts.