Diversity of the National Medical Student Body - Four Decades of Inequities.

A racially and ethnically diverse health care workforce remains a distant goal, the attainment of which is contingent on the inclusivity of the national medical student body. We examined the diversity of medical school applicants and enrollees over the past four decades with an eye toward assessing the progress made. Data on the gender and race or ethnic group of enrollees in all medical doctorate degree-granting U.S. medical schools from 1978 through 2019 were examined. The percentage of female enrollees doubled during this period, and women now constitute more than half the national medical student body. This upturn has been attributed largely to an increase by a factor of 12 in the enrollment of Asian women. The corresponding decrease in the percentage of male enrollees, most notably White men, was offset by an increase by a factor of approximately 5 in the enrollment of Asian men. The percentages of enrollees from Black, Hispanic, and other racial and ethnic groups that are underrepresented in medicine remain well below the percentages of these groups in the national Census.

Ventilatory Strategies in Infants with Established Severe Bronchopulmonary Dysplasia: A Multicenter Point Prevalence Study.

We performed a point prevalence study on infants with severe bronchopulmonary dysplasia (BPD), collecting data on type and settings of ventilatory support; 187 infants, 51% of whom were on invasive positive-pressure ventilation (IPPV), from 15 centers were included. We found a significant center-specific variation in ventilator modes.

A lipidome-wide association study of the lipoprotein insulin resistance index.

BACKGROUND: The lipoprotein insulin resistance (LPIR) score was shown to predict insulin resistance (IR) and type 2 diabetes (T2D) in healthy adults. However, the molecular basis underlying the LPIR utility for classification remains unclear. OBJECTIVE: To identify small molecule lipids associated with variation in the LPIR score, a weighted index of lipoproteins measured by nuclear magnetic resonance, in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study (n = 980). METHODS: Linear mixed effects models were used to test the association between the LPIR score and 413 lipid species and their principal component analysis-derived groups. Significant associations were tested for replication with homeostatic model assessment-IR (HOMA-IR), a phenotype correlated with the LPIR score (r = 0.48, p <  0.001), in the Heredity and Phenotype Intervention (HAPI) Heart Study (n = 590). RESULTS: In GOLDN, 319 lipids were associated with the LPIR score (false discovery rate-adjusted p-values ranging from 4.59 × 10- 161 to 49.50 × 10- 3). Factors 1 (triglycerides and diglycerides/storage lipids) and 3 (mixed lipids) were positively (ß = 0.025, p = 4.52 × 10- 71 and ß = 0.021, p = 5.84 × 10- 41, respectively) and factor 2 (phospholipids/non-storage lipids) was inversely (ß = - 0.013, p = 2.28 × 10- 18) associated with the LPIR score. These findings were replicated for HOMA-IR in the HAPI Heart Study (ß = 0.10, p = 1.21 × 10- 02 for storage, ß = - 0.13, p = 3.14 × 10- 04 for non-storage, and ß = 0.19, p = 8.40 × 10- 07 for mixed lipids). CONCLUSIONS: Non-storage lipidomics species show a significant inverse association with the LPIR metabolic dysfunction score and present a promising focus for future therapeutic and prevention studies.

Preventing the Early Introduction of Juice and Sugar-Sweetened Beverages in Infants' Diets: A Randomized Controlled Trial.

A randomized controlled trial was conducted to determine whether a simple educational intervention targeting parents of young infants could have an impact on the consumption of juice and sugar-sweetened beverages (SSBs) in early childhood and decrease overweight and obesity rates. Parents of 2- to 4-month-old infants were randomized into intervention (n = 67) and control (n = 77) groups. Parents completed questionnaires about juice and SSB consumption and knowledge at baseline and 1-year follow-up. Intervention parents received informational handouts and watched videos about the health effects of juice and SSBs. Knowledge about juice increased significantly in the intervention group compared with control (P < .01) and was significantly higher in black/African American parents (P < .05) and those with some college education (P < .05). The intervention had a significant impact on the knowledge gained by parents about the health effects of juice and SSBs but did not decrease the consumption of sugary drinks or change children's weight status.

Diet Quality and the Gut Microbiota in Women Living in Alabama.

INTRODUCTION: The gut microbiota is associated with obesity and modulated by individual dietary components. However, the relationships between diet quality and the gut microbiota and their potential interactions with weight status in diverse populations are not well understood. This study examined the associations between overall diet quality, weight status, and the gut microbiota in a racially balanced sample of adult females. METHODS: Female participants (N=71) residing in Birmingham, Alabama provided demographics, anthropometrics, biospecimens, and dietary data in this observational study from March 2014 to August 2014, and data analysis was conducted from August 2017 to March 2019. Weight status was defined as a BMI (weight [kg]/height [m2]) <30 kg/m2 for non-obese participants and ≥30 kg/m2 for participants who were obese. Dietary data collected included an Automated Self-Administered 24-Hour recall and Healthy Eating Index-2010 (HEI-2010) score. Diet quality was defined as having a high HEI score (≥median) or a low HEI score (

Effects of environmental variability on superspreading transmission events in stochastic epidemic models.

Superspreaders (individuals with a high propensity for disease spread) have played a pivotal role in recent emerging and re-emerging diseases. In disease outbreak studies, host heterogeneity based on demographic (e.g. age, sex, vaccination status) and environmental (e.g. climate, urban/rural residence, clinics) factors are critical for the spread of infectious diseases, such as Ebola and Middle East Respiratory Syndrome (MERS). Transmission rates can vary as demographic and environmental factors are altered naturally or due to modified behaviors in response to the implementation of public health strategies. In this work, we develop stochastic models to explore the effects of demographic and environmental variability on human-to-human disease transmission rates among superspreaders in the case of Ebola and MERS. We show that the addition of environmental variability results in reduced probability of outbreak occurrence, however the severity of outbreaks that do occur increases. These observations have implications for public health strategies that aim to control environmental variables.

Introducing Juice and Sugar-Sweetened Beverages in Early Infancy: Parental Knowledge and Intended Behaviors.

OBJECTIVE: Assess caregivers' knowledge about juice and sugar-sweetened beverages (SSBs) and identify factors that contribute to their early introduction. METHODS: One hundred forty-four parents of young infants completed a 45-item questionnaire focused on infant nutrition. RESULTS: Seventy-two percent of parents plan to give juice to their babies starting in the first year of life; only 16% plan to introduce SSBs. Parents with some college education or more were significantly less likely to report an intention to introduce juice (P < .0001) and SSBs (P < .001) in their children's diets. Education level was significantly associated with knowledge about juice and SSBs (P < .001). Parents with higher knowledge were significantly less likely to plan on introducing juice (P < .001) and SSBs (P < .001). CONCLUSION: Parents of young infants lack enough knowledge about the detrimental effects of juice and sugary drinks. These knowledge gaps give pediatric providers a unique opportunity to provide anticipatory guidance starting in early infancy on the adverse health effects of juice and SSBs.

Comparison of Resident and Faculty Screening for Social Determinants of Health in an Academic Pediatric Primary Care Practice.

BACKGROUND: Social determinants of health (SDH) have an important role in children's health and development and should be investigated in pediatric well child care. METHODS: A retrospective chart review of children aged 5-17 at well visits at an urban academic pediatric primary care practice was performed. Chi-square tests of independence and z-test for proportions were used to assess differences between residents and faculty SDH screening.  Results: Faculty screened for SDH more frequently than residents (P<0.05). Residents screened less frequently for food insecurity (P<0.05) and financial insecurity (P<0.05). Financial insecurity was endorsed less frequently by resident families (P<0.05), while school absence was endorsed more frequently by resident families (P<0.05). Referrals to the clinic's community resource desk did not differ between residents and faculty. CONCLUSIONS: Differences exist in screening and need between clinician groups. Despite these differences, there was no difference in community resource desk referrals.

Variation in microparasite free-living survival and indirect transmission can modulate the intensity of emerging outbreaks.

Variation in free-living microparasite survival can have a meaningful impact on the ecological dynamics of established and emerging infectious diseases. Nevertheless, resolving the importance of indirect and environmental transmission in the ecology of epidemics remains a persistent challenge. It requires accurately measuring the free-living survival of pathogens across reservoirs of various kinds and quantifying the extent to which interaction between hosts and reservoirs generates new infections. These questions are especially salient for emerging pathogens, where sparse and noisy data can obfuscate the relative contribution of different infection routes. In this study, we develop a mechanistic, mathematical model that permits both direct (host-to-host) and indirect (environmental) transmission and then fit this model to empirical data from 17 countries affected by an emerging virus (SARS-CoV-2). From an ecological perspective, our model highlights the potential for environmental transmission to drive complex, nonlinear dynamics during infectious disease outbreaks. Summarizing, we propose that fitting alternative models with indirect transmission to real outbreak data from SARS-CoV-2 can be useful, as it highlights that indirect mechanisms may play an underappreciated role in the dynamics of infectious diseases, with implications for public health.

Variation in SARS-CoV-2 free-living survival and environmental transmission can modulate the intensity of emerging outbreaks.

Variation in free-living, microparasite survival can have a meaningful impact on the ecological dynamics of established and emerging infectious diseases. Nevertheless, resolving the importance of environmental transmission in the ecology of epidemics remains a persistent challenge, requires accurate measuring the free-living survival of pathogens across reservoirs of various kinds, and quantifying the extent to which interaction between hosts and reservoirs generates new infections. These questions are especially salient for emerging pathogens, where sparse and noisy data can obfuscate the relative contribution of different infection routes. In this study, we develop a mechanistic, mathematical model that permits both direct (host-to-host) and indirect (environmental) transmission and then fit this model to empirical data from 17 countries affected by an emerging virus (SARS-CoV-2). From an ecological perspective, our model highlights the potential for environmental transmission to drive complex, non-linear dynamics during infectious disease outbreaks. Summarizing, we propose that fitting such models with environmental transmission to real outbreak data from SARS-CoV-2 transmission highlights that variation in environmental transmission is an underappreciated aspect of the ecology of infectious disease, and an incomplete understanding of its role has consequences for public health interventions.

Cost analysis of treatment strategies for the control of HSV-2 infection in the U.S.: A mathematical modeling-based case study.

Infection of Herpes Simplex Virus type 2 (HSV-2) is a lifelong sexually transmitted disease. According to the Center for Disease Control and Prevention (CDC), 11.9% of the United States (U.S.) population was infected with HSV-2 in 2015-2016. The HSV-2 pathogen establishes latent infections in neural cells and can reactivate causing lesions later in life, a strategy that increases pathogenicity and allows the virus to evade the immune system. HSV-2 infections are currently treated by Acyclovir only in the non-constitutional stage, marked by genital skin lesions and ulcers. However, patients in the constitutional stage expressing mild and common (with other diseases) symptoms, such as fever, itching and painful urination, remain difficult to detect and are untreated. In this study, we develop and analyze a mathematical model to study the transmission and control of HSV-2 among the U.S. population between the ages of 15-49 when there are options to treat individuals in different stages of their pathogenicity. In particular, the goals of this work are to study the effect on HSV-2 transmission dynamics and to evaluate and compare the cost-effectiveness of treating HSV-2 infections in both constitutional and non-constitutional stages (new strategy) against the current conventional treatment protocol for treating patients in the non-constitutional stage (current strategy). Our results distinguish model parameter regimes where each of the two treatment strategies can optimize the available resources and consequently gives the long-term reduced cost associated with each treatment and incidence. Moreover, we estimated that the public health cost of HSV-2 with the proposed most cost-effective treatment strategy would increase by approximately 1.63% in 4 years of implementation. However, in the same duration, early treatment via the new strategy will reduce HSV-2 incidence by 42.76% yearly and the reproduction number will decrease to 0.84 from its current estimate of 2.5. Thus, the proposed new strategy will be significantly cost-effective in controlling the transmission of HSV-2 if the strategy is properly implemented.

Modeling the dynamics of glucose, insulin, and free fatty acids with time delay: The impact of bariatric surgery on type 2 diabetes mellitus.

The role of free fatty acids (FFA) on Type 2 diabetes mellitus (T2DM) progression has been studied extensively with prior studies suggesting that individuals with shared familial genetic predisposition to metabolic-related diseases may be vulnerable to dysfunctional plasma FFA regulation. A harmful cycle arises when FFA are not properly regulated by insulin contributing to the development of insulin resistance, a key indicator for T2DM, since prolonged insulin resistance may lead to hyperglycemia. We introduce a hypothesis-driven dynamical model and use it to evaluate the role of FFA on insulin resistance progression that is mathematically constructed within the context of individuals that have genetic predisposition to dysfunctional plasma FFA. The dynamics of the nonlinear interactions that involve glucose, insulin, and FFA are modeled by incorporating a fixed-time delay with the corresponding delay-differential equations being studied numerically. The results of computational studies, that is, extensive simulations, are compared to the known minimal ordinary differential equations model. Parameter estimation and model validation are carried out using clinical data of patients who underwent bariatric surgery. These estimates provide a quantitative measure that is used to evaluate the regulation of lipolysis by insulin action measured by insulin sensitivity, within a metabolically heterogeneous population (non-diabetic to diabetic). Results show that key metabolic factors improve after surgery, such as the effect of insulin inhibition of FFA on insulin and glucose regulation, results that do match prior clinical studies. These findings indicate that the reduction in weight or body mass due to surgery improve insulin action for the regulation of glucose, FFA, and insulin levels. This reinforces what we know, namely, that insulin action is essential for regulating FFA and glucose levels and is a robust effect that can be observed not only in the long-term, but also in the short-term; thereby preventing the manifestation of T2DM.

The association between allostatic load and anthropometric measurements among a multiethnic cohort of children.

OBJECTIVE: This study investigated if levels of allostatic load (ALoad) differed according to race/ethnicity in children and if ALoad was associated with obesity-related measures. METHODS: A multiethnic sample of 307 children aged seven to 12 was evaluated, composed of 39% European American (EA), 35% African American (AA), and 26% Hispanic American (HA) youth. Anthropometric measurements were evaluated by dual-energy X-ray absorptiometry, and other measurements included body mass index (BMI) and waist circumference (WC). Allostatic load scores were estimated based on two different calculations, including seven and eight biomarkers (ALoad1 and ALoad2), respectively. Analyses of variance, independence tests, and multiple regression models were performed. RESULTS: From the total sample, 22.80% (n = 70) of children were characterized as "no load," 46.58% (n = 143) "low load," and 30.62% (n = 94) "high load." Hispanic American children showed the highest ALoad scores (2.07 ± 1.54; 95% CI, 1.73-2.41) compared with AA children (1.71 ± 1.43; 95% CI, 1.43-1.99) and EA children (1.56 ± 1.34; 95% CI, 1.32-1.80) (P < 0.05). Higher scores of ALoad (using both ALoad1 and ALoad2 calculations) were associated with higher BMI, total body fat mass, body percent fat, and WC (P < 0.05). CONCLUSION: Significant differences in ALoad were observed in children according to race/ethnicity. Increased exposure to stressors captured by ALoad may result in increased risk for excessive adiposity and potential health risk in children. Further, ALoad may serve as a preventive marker for conditions known to continue throughout adulthood.

A Systematic Scoping Review of Surgically Manipulated Adipose Tissue and the Regulation of Energetics and Body Fat in Animals.

OBJECTIVE: Surgical manipulations of adipose tissue by removal, or partial lipectomy, have demonstrated body fat compensation and recovered body weight, suggesting that the body is able to resist changes to body composition. However, the mechanisms underlying these observations are not well understood. The purpose of this scoping review is to provide an update on what is currently known about the regulation of energetics and body fat after surgical manipulations of adipose tissue in small mammals. METHODS: PubMed and Scopus were searched to identify 64 eligible studies. Outcome measures included body fat, body weight, food intake, and circulating biomarkers. RESULTS: Surgeries performed included lipectomy (72%) or transplantation (12%) in mice (35%), rats (35%), and other small mammals. Findings suggested that lipectomy did not have consistent long-term effects on reducing body weight and fat because regain occurred within 12 to 14 weeks post surgery. Hence, biological feedback mechanisms act to resist long-term changes of body weight or fat. Furthermore, whether this weight and fat regain occurred because of "passive" and "active" regulation under the "set point" or "settling point" theories cannot fully be discerned because of limitations in study designs and data collected. CONCLUSIONS: The regulation of energetics and body fat are complex and dynamic processes that require further studies of the interplay of genetic, physiological, and behavioral factors.

Illustration of Measurement Error Models for Reducing Bias in Nutrition and Obesity Research Using 2-D Body Composition Data.

OBJECTIVE: This study aimed to illustrate the use and value of measurement error models for reducing bias when evaluating associations between body fat and having type 2 diabetes (T2D) or being physically active. METHODS: Logistic regression models were used to evaluate T2D and physical activity among adults aged 19 to 80 years from the Photobody Study (n = 558). Self-reported T2D and physical activity were categorized as "yes" or "no." Body fat measured by two-dimensional photographs was adjusted for bias using dual-energy x-ray absorptiometry scans as a reference. Three approaches were applied: regression calibration (RC), simulation extrapolation (SIMEX), and multiple imputation (MI). RESULTS: Unadjusted two-dimensional measures of body fat had upward biases of 30% and 233% for physical activity and T2D, respectively. For the physical activity model, RC-adjusted values had a 13% upward bias, whereas MI and SIMEX decreased the bias to 9% and 91%, respectively. For the T2D model, MI reduced the bias to 0%, whereas RC and SIMEX increased the upward bias to > 300%. CONCLUSIONS: Of three statistical approaches to reducing bias due to measurement errors, MI performed best in comparison to RC and SIMEX. Measurement error methods can improve the reliability of analyses that look for relations between body fat measures and health outcomes.

Modeling the Diet Dynamics of Children: the Roles of Socialization and the School Environment.

Childhood obesity is a health emergency in many parts of the world including the U.S. and, consequently, identifying local, regional or national intervention models capable, of altering the dynamics of obesity at scales that make a difference remains a challenge. The fact that consumption of healthful foods among most youth has yet to meet recommended nutritional standards highlights a lack of effective policies aimed at addressing the epidemic of obesity. Mathematical models are used to evaluate the roles of socialization and school environment on the diet dynamics of children. Data suggest that standard nutrition education programs may have, at best, minimal impact in altering diet dynamics at the population-level. Inclusion of peer influence (model as contagion) reinforced by the use of culturally-sensitive school menus (environmental disruption) may prove capable of modifying obesity enhancing diet dynamics; altering the diets of a significant (critical) proportion of youngsters. A framework is introduced to explore the value of behavior-based interventions and policies that account for the sociocultural environments of at risk communities. These models capture carefully choreographed scenarios to account for the fact that when dealing with diet-dynamics systems, thinking additively is not enough as it cannot account for the power of nonlinear effects.

Modeling eating behaviors: The role of environment and positive food association learning via a Ratatouille effect.

Eating behaviors among a large population of children are studied as a dynamic process driven by nonlinear interactions in the sociocultural school environment. The impact of food association learning on diet dynamics, inspired by a pilot study conducted among Arizona children in Pre-Kindergarten to 8th grades, is used to build simple population-level learning models. Qualitatively, mathematical studies are used to highlight the possible ramifications of instruction, learning in nutrition, and health at the community level. Model results suggest that nutrition education programs at the population-level have minimal impact on improving eating behaviors, findings that agree with prior field studies. Hence, the incorporation of food association learning may be a better strategy for creating resilient communities of healthy and non-healthy eaters. A Ratatouille effect can be observed when food association learners become food preference learners, a potential sustainable behavioral change, which in turn, may impact the overall distribution of healthy eaters. In short, this work evaluates the effectiveness of population-level intervention strategies and the importance of institutionalizing nutrition programs that factor in economical, social, cultural, and environmental elements that mesh well with the norms and values in the community.