Infant Television Watching Predicts Toddler Television Watching in a Low-Income Population.

OBJECTIVE: This study examines the development of active television (TV) watching behaviors across the first 2 years of life in a racially and ethnically diverse, low-income cohort and identifies caregiver and child predictors of early TV watching. METHODS: We used longitudinal data from infants enrolled in the active control group (N = 235; 39% Latino; 29% Black; 15% White) of Greenlight, a cluster randomized multisite trial to prevent childhood obesity. At preventive health visits from 2 months to 2 years, caregivers were asked: "How much time does [child's first name] spend watching television each day?" Proportional odds models and linear regression analyses were used to assess associations among TV introduction age, active TV watching amount at 2 years, and sociodemographic factors. RESULTS: Sixty-eight percent of children watched TV by 6 months, and 88% by 2 years. Age of TV introduction predicted amount of daily active TV watching at 2 years, with a mean time of 93 minutes if starting at 2 months; 64 minutes if starting at 4 or 6 months; and 42 minutes if starting after 6 months. Factors predicting earlier introduction included lower income, fewer children in household, care away from home, male sex, and non-Latino ethnicity of child. CONCLUSIONS: Many caregivers report that their infants actively watch TV in the first 6 months of life. Earlier TV watching is related to sociodemographic factors yet predicts more daily TV watching at 2 years even controlling those factors. Interventions to limit early TV watching should be initiated in infancy.

Applying the Stress Process Model to Stress-Burnout and Stress-Depression Relationships in Biomedical Doctoral Students: A Cross-Sectional Pilot Study.

Although doctoral students in the biomedical sciences have been recognized as a population at particular risk for mental health problems such as burnout and depression, little research has been conducted to identify candidate targets for intervention. To this end, we used the stress process model to evaluate potential mediators of stress-burnout and stress-depression relationships in biomedical doctoral students. A cross-sectional sample (n = 69) completed validated self-report measures of stress; symptoms of burnout and depression; and perceptions of mastery, social support, and advisor support. In linear regression models, we found that academic stressors were most predictive of burnout, whereas family/monetary stressors were most predictive of depression. In mediation models, we found that the relationship between stress and burnout was partially mediated by mastery and advisor support, while the stress-depression relationship was partially mediated by mastery. These findings represent a first step in identifying interventional targets to improve mental health in this at-risk population. Whereas certain stressors are inherent to the doctoral training environment, psychosocial interventions to enhance one's sense of mastery and/or to improve advisor relationships may mitigate the influence of such stressors on burnout and depression.

Burnout and Mental Health Problems in Biomedical Doctoral Students.

Although burnout and mental health problems may adversely impact quality of scientific research, academic productivity, and attrition in biomedical doctoral training programs, very little research has been done on this topic. Recent studies have used brief survey methods to begin to explore burnout and mental health problems in biomedical doctoral students. In this pilot study, biomedical doctoral students (N = 69; 12% of enrolled biomedical doctoral students at a large research institution's school of medicine in the United States) were administered standardized psychiatric interviews and self-report questionnaires focused on dimensions of burnout, mental health symptoms, and academic outcomes. We discovered high levels of burnout, depression, and anxiety. Additionally, we identified that burnout was significantly associated with thoughts related to dropping out, subjective appraisal of employment opportunities, functional impairment due to a mental health problem, and having at least one current psychiatric disorder. These findings extend prior research indicating the presence of significant emotional health challenges doctoral students in biomedical graduate programs face involving high burnout and difficulties with the training environment. We outline several recommendations and next steps to programmatically understand and address these emerging emotional wellness concerns in biomedical doctoral students.

E-Cadherin Represses Anchorage-Independent Growth in Sarcomas through Both Signaling and Mechanical Mechanisms.

CDH1 (also known as E-cadherin), an epithelial-specific cell-cell adhesion molecule, plays multiple roles in maintaining adherens junctions, regulating migration and invasion, and mediating intracellular signaling. Downregulation of E-cadherin is a hallmark of epithelial-to-mesenchymal transition (EMT) and correlates with poor prognosis in multiple carcinomas. Conversely, upregulation of E-cadherin is prognostic for improved survival in sarcomas. Yet, despite the prognostic benefit of E-cadherin expression in sarcoma, the mechanistic significance of E-cadherin in sarcomas remains poorly understood. Here, by combining mathematical models with wet-bench experiments, we identify the core regulatory networks mediated by E-cadherin in sarcomas, and decipher their functional consequences. Unlike carcinomas, E-cadherin overexpression in sarcomas does not induce a mesenchymal-to-epithelial transition (MET). However, E-cadherin acts to reduce both anchorage-independent growth and spheroid formation of sarcoma cells. Ectopic E-cadherin expression acts to downregulate phosphorylated CREB1 (p-CREB) and the transcription factor, TBX2, to inhibit anchorage-independent growth. RNAi-mediated knockdown of TBX2 phenocopies the effect of E-cadherin on CREB levels and restores sensitivity to anchorage-independent growth in sarcoma cells. Beyond its signaling role, E-cadherin expression in sarcoma cells can also strengthen cell-cell adhesion and restricts spheroid growth through mechanical action. Together, our results demonstrate that E-cadherin inhibits sarcoma aggressiveness by preventing anchorage-independent growth. IMPLICATIONS: We highlight how E-cadherin can restrict aggressive behavior in sarcomas through both biochemical signaling and biomechanical effects.

Induction of Mesenchymal-Epithelial Transitions in Sarcoma Cells.

Phenotypic plasticity refers to a phenomenon in which cells transiently gain traits of another lineage. During carcinoma progression, phenotypic plasticity drives invasion, dissemination and metastasis. Indeed, while most of the studies of phenotypic plasticity have been in the context of epithelial-derived carcinomas, it turns out sarcomas, which are mesenchymal in origin, also exhibit phenotypic plasticity, with a subset of sarcomas undergoing a phenomenon that resembles a mesenchymal-epithelial transition (MET). Here, we developed a method comprising the miR-200 family and grainyhead-like 2 (GRHL2) to mimic this MET-like phenomenon observed in sarcoma patient samples.We sequentially express GRHL2 and the miR-200 family using cell transduction and transfection, respectively, to better understand the molecular underpinnings of these phenotypic transitions in sarcoma cells. Sarcoma cells expressing miR-200s and GRHL2 demonstrated enhanced epithelial characteristics in cell morphology and alteration of epithelial and mesenchymal biomarkers. Future studies using these methods can be used to better understand the phenotypic consequences of MET-like processes on sarcoma cells, such as migration, invasion, metastatic propensity, and therapy resistance.

Reproductive interference by male Drosophila subobscura on female D. persimilis: A laboratory experiment.

While females often reject courtship attempts by heterospecific males, reproductive interference by harassment from such males can nonetheless occur, potentially reducing female fitness. Such effects may be profound following a range expansion, when males from a new species may suddenly encounter (and perhaps even become abundant relative to) females of related native species. Drosophila subobscura recently invaded North America and may impact native species through reproductive interference and other processes. We test for the potential for reproductive interference by D. subobscura males on D. persimilis females in the laboratory. D. subobscura males aggressively copulated with D. persimilis females, including many females that exhibit rejection behaviors. Despite females attempting to dismount the males, the heterospecific copulations are on average longer than conspecific copulations, and females exhibit some reluctance to remate with conspecific males following this harassment. Females confined with both conspecific and heterospecific males produce fewer adult progeny than those with either conspecific males only or with conspecific males and distantly related D. simulans males that do not engage in female harassment. Overall, our results illustrate how reproductive interference by an invasive species can have negative effects on resident natural populations.

Mesenchymal-Epithelial Transition in Sarcomas Is Controlled by the Combinatorial Expression of MicroRNA 200s and GRHL2.

Phenotypic plasticity involves a process in which cells transiently acquire phenotypic traits of another lineage. Two commonly studied types of phenotypic plasticity are epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET). In carcinomas, EMT drives invasion and metastatic dissemination, while MET is proposed to play a role in metastatic colonization. Phenotypic plasticity in sarcomas is not well studied; however, there is evidence that a subset of sarcomas undergo an MET-like phenomenon. While the exact mechanisms by which these transitions occur remain largely unknown, it is likely that some of the same master regulators that drive EMT and MET in carcinomas also act in sarcomas. In this study, we combined mathematical models with bench experiments to identify a core regulatory circuit that controls MET in sarcomas. This circuit comprises the microRNA 200 (miR-200) family, ZEB1, and GRHL2. Interestingly, combined expression of miR-200s and GRHL2 further upregulates epithelial genes to induce MET. This effect is phenocopied by downregulation of either ZEB1 or the ZEB1 cofactor, BRG1. In addition, an MET gene expression signature is prognostic for improved overall survival in sarcoma patients. Together, our results suggest that a miR-200, ZEB1, GRHL2 gene regulatory network may drive sarcoma cells to a more epithelial-like state and that this likely has prognostic relevance.

Temporal Stability of Molecular Diversity Measures in Natural Populations of Drosophila pseudoobscura and Drosophila persimilis.

Many molecular ecological and evolutionary studies sample wild populations at a single point in time, but that data represents genetic variation from a potentially unrepresentative snapshot in time. Variation across time in genetic parameters may occur quickly in species that produce multiple generations of offspring per year. Here, we compare genetic diversity in wild caught populations of Drosophila persimilis and Drosophila pseudoobscura collected 16 years apart at the same time of year and same site at 4 X-linked and 2 mitochondrial loci to assess genetic stability. We found no major changes in nucleotide diversity in either species, but we observed a drastic shift in Tajima's D between D. pseudoobscura timepoints at 1 locus associated with increased abundance of a set of related haplotypes. Our data also suggests that D. persimilis may have recently accelerated its demographic expansion. While the changes we observed were modest, this study reinforces the importance of considering potential temporal variation in genetic parameters within single populations over short evolutionary timescales.