Motility induced changes in viscosity of suspensions of swimming microbes in extensional flows

Suspensions of motile cells are model systems for understanding the unique mechanical properties of living materials which often consist of ensembles of self-propelled particles. We present here a quantitative comparison of theory against experiment for the rheology of such suspensions. The influence of motility on viscosities of cell suspensions is studied using a novel acoustically-driven microfluidic capillary-breakup extensional rheometer. Motility increases the extensional viscosity of suspensions of algal pullers, but decreases it in the case of bacterial or sperm pushers. A recent model [Saintillan, Phys. Rev. E, 2010, 81:56307] for dilute active suspensions is extended to obtain predictions for higher concentrations, after independently obtaining parameters such as swimming speeds and diffusivities. We show that details of body and flagellar shape can significantly determine macroscale rheological behaviour.Comment: 12 pages, 1 appendix, 7 figures, submitted to Soft Matter - under revie

Child Temperamental Regulation and Classroom Quality in Head Start: Considering the Role of Cumulative Economic Risk

There is growing recognition that cumulative economic risk places children at higher risk for depressed academic competencies (Crosnoe & Cooper, 2010; NCCP, 2008; Sameroff, 2000). Yet, children’s temperamental regulation and the quality of the early childhood classroom environment have been associated with better academic skills. This study is an examination of prekindergarten classroom quality (instructional support, emotional support, organization) as a moderator between temperamental regulation and early math and literacy skills for children at varying levels of cumulative economic risk. The sample includes children enrolled in Head Start programs drawn from the FACES 2009 study. Three main findings emerged. First, for lower and highest risk children, more instructional support was associated with better math performance when children had high levels of temperamental regulation but poorer performance when children had low temperamental regulation. Second, among highest risk children, low instructional support was protective for math performance for children with low temperamental regulation and detrimental for those with high temperamental regulation. Third, for highest risk children, high classroom organization predicted better literacy scores for those with high temperamental regulation. Children with low temperamental regulation were expected to perform about the same, regardless of the level of classroom organization. Implications are discussed

RhoA is dispensable for axon guidance of sensory neurons in the mouse dorsal root ganglia

RhoA, a member of the Rho family small GTPases, has been shown to play important roles in axon guidance. However, to date, the physiological function of RhoA in axon guidance events in vivo has not been determined genetically in animals. Here we show that RhoA mRNA is strongly expressed by sensory neurons in the developing mouse dorsal root ganglia (DRG). We have deleted RhoA in sensory neurons of the DRG using RhoA-floxed mice under the Wnt1-Cre driver in which Cre is strongly expressed in sensory neurons. Peripheral projections of sensory neurons appear normal and there are no detectable defects in the central projections of either cutaneous or proprioceptive sensory neurons in RhoAf/f; Wnt1-Cre mice. Furthermore, a co-culture assay using DRG explants from RhoAf/f; Wnt1-Cre embryos, and 293T cells expressing semaphorin3A (Sema3A) reveals that RhoA is not required for Sema3A-mediated axonal repulsion of sensory neurons. Expression of RhoC, a closely related family member, is increased in RhoA-deficient sensory neurons and may play a compensatory role in this context. Taken together, these genetic studies demonstrate that RhoA is dispensable for peripheral and central projections of sensory neurons in the DRG

Healthcare preferences among lesbians: a focus group analysis

OBJECTIVE: The healthcare needs of lesbians are not well understood. We sought to characterize lesbians\u27 experiences with, and preferences for, women\u27s healthcare. METHODS: We conducted three age-stratified focus groups (18-29, 30-50, and \u3e50 years) with a total of 22 participants using a semistructured interview guide to elicit lesbians\u27 experiences and preferences. We analyzed transcripts of these audiotaped sessions using the constant comparative method of grounded theory. Community-dwelling women who self-identified as lesbian and responded to advertisements were selected on first-come basis. RESULTS: Participants voiced experiences and preferences for healthcare that emerged into three themes: desired models of care, desired processes of care, and desired patient-provider relationship. Each theme was further developed into multiple subthemes. Within the subthemes we identified issues that were specific to lesbians and those that were general women\u27s health issues. Participants preferred, but did not always receive, care that is comprehensive in scope, person centered, nondiscriminatory, and inclusive of them as lesbians. CONCLUSIONS: Healthcare providers, institutions, and society should adopt an inviting, person-centered approach toward lesbians seeking healthcare, assure them access to healthcare information, and establish healthcare delivery systems that take all aspects of health into account

Distinct fos-expressing neuronal ensembles in the ventromedial prefrontal cortex mediate food reward and extinction memories

In operant learning, initial reward-associated memories are thought to be distinct from subsequent extinction-associated memories. Memories formed during operant learning are thought to be stored in “neuronal ensembles.” Thus, we hypothesize that different neuronal ensembles encode reward- and extinction-associated memories. Here, we examined prefrontal cortex neuronal ensembles involved in the recall of reward and extinction memories of food self-administration.Wefirst trained rats to lever press for palatable food pellets for 7 d (1 h/d) and then exposed them to 0, 2, or 7 daily extinction sessions in which lever presses were not reinforced. Twenty-four hours after the last training or extinction session, we exposed the rats to either a short 15 min extinction test session or left them in their homecage (a control condition). We found maximal Fos (a neuronal activity marker) immunoreactivity in the ventral medial prefrontal cortex of rats that previously received 2 extinction sessions, suggesting that neuronal ensembles in this area encode extinction memories. We then used the Daun02 inactivation procedure to selectively disrupt ventral medial prefrontal cortex neuronal ensembles that were activated during the 15 min extinction session following 0 (no extinction) or 2 prior extinction sessions to determine the effects of inactivating the putative food reward and extinction ensembles, respectively, on subsequent nonreinforced food seeking 2 d later. Inactivation of the food reward ensembles decreased food seeking, whereas inactivation of the extinction ensembles increased food seeking. Our results indicate that distinct neuronal ensembles encoding operant reward and extinction memories intermingle within the same cortical area

Sickle cell trait and risk of cognitive impairment in African-Americans: The REGARDS cohort

Background: Sickle cell anemia may be associated with cognitive dysfunction, and some complications of sickle cell anemia might affect those with sickle cell trait (SCT), so we hypothesized that SCT is a risk factor for cognitive impairment. Methods: The Reasons for Geographic and Racial Differences in Stroke (REGARDS) study enrolled a national cohort of 30,239 white and black Americans from 2003 to 7, who are followed every 6 months. Baseline and annual global cognitive function testing used the Six-Item Screener (SIS), a validated instrument (scores range 0-6; ≤ 4 indicates cognitive impairment). Participants with baseline cognitive impairment and whites were excluded. Logistic regression was used to calculate the association of SCT with incident cognitive impairment, adjusted for risk factors. Linear mixed models assessed multivariable-adjusted change in test scores on a biennially administered 3-test battery measuring learning, memory, and semantic and phonemic fluency. Findings: Among 7743 participants followed for a median of 7·1 years, 85 of 583 participants with SCT (14·6%) developed incident cognitive impairment compared to 902 of 7160 (12·6%) without SCT. In univariate analysis, the odds ratio (OR) of incident cognitive impairment was 1·18 (95% CI: 0·93, 1·51) for those with SCT vs. those without. Adjustment did not impact the OR. There was no difference in change on 3-test battery scores by SCT status (all p > 0·11). Interpretation: In this prospective cohort study of black Americans, SCT was not associated with incident cognitive impairment or decline in test scores of learning, memory and executive function. Funding: National Institutes of Health, American Society of Hematology

Knowledge of and perceived need for evidence-based educational materials about antipsychotic medication safety by nursing home staff

Background: Given the widespread overuse of antipsychotic medications among US nursing home (NH) residents, we sought to identify knowledge of and perceived need for the AHRQ Comparative Effectiveness Research Summary Guide (CERSG) “Off-Label Use of Atypical Antipsychotic Drugs”. Methods: We conducted a baseline needs assessment with 12 NHs participating in a randomized controlled trail evaluating evidence dissemination strategies. Using a mixed method approach, we conducted in-depth assessments of knowledge, attitudes, and practice behavior using telephone interviews with NH leadership (administrators, directors of nursing [DON], and medical directors), and questionnaires with NH leadership, consultant pharmacists and direct care staff. Interviews were transcribed, verbatim responses were coded independently by 2 project staff. The coding scheme was revised after each round until substantial agreement (85%) was reached. Results: Interviews revealed that 70% of medical directors and 46% of DON and administrators believed that antipsychotics decreased agitation and controlled harmful behavior; 50% of medical directors and 7% of DONs & administrators reported knowledge of the increased risk of morbidity and mortality due to atypical antipsychotics. Half of administrators and DONs expressed interest in receiving information for NH staff pertaining to understanding dementia and dementia-related behaviors, 42% believed families would benefit from information about antipsychotic use for dementia-related behaviors. Questionnaire results were similar. When leaders were asked to list any risks associated with antipsychotic use for residents with dementia, only 17% reported death as a possible adverse event; licensed nursing staff (RN and LPNs) reported death 5% of the time. Over half of consultant pharmacists identified that their biggest barrier to improving medication use in challenging NHs was physician resistance to accepting recommendations. Conclusions: The responses of the NH leaders, staff and consultant pharmacists suggest widespread knowledge gaps regarding antipsychotic benefits and risks, and suggest a need for increase evidence dissemination and broad organizational change

Screening for eating disorders in adolescents with chronic pain: the Eating Attitudes Test– 16–Chronic Pain

Background Few measures have been validated to screen for eating disorders (ED) in youth with chronic pain. We conducted confirmatory (CFA) of two established factor structures of the Eating Attitudes Test-26 (EAT-26) in a sample of youth with chronic pain attending an intensive interdisciplinary pain treatment (IIPT) program and examined the validity of the best-fitting model in predicting ED diagnoses in this sample. Methods Participants were 880 adolescents (M age = 16.1, SD = 2.1) consecutively admitted into an IIPT program who completed the EAT-26 upon admission. CFA was conducted and in the case of inadequate fit, EFA was planned to identify alternative models. Factors of the best-fitting model were included in a logistic regression analysis to predict ED diagnoses. Results The TLIs (0.70; 0.90), RMSEAs (0.09; 0.07) and CFIs (0.73; 0.92) suggested poor fit of one model and adequate of the second model. Goodness of fit indices from EFA (TLI:0.85, RMSEA:0.06) did not outperform the fit of the second CFA. As such, the second model was retained with the exception of one factor. The items loaded onto a 16-item, five factor model: Fear of Getting Fat, Social Pressure to Gain Weight, Eating-Related Control, Eating-Related Guilt and Food Preoccupation. Based on chart review, 19.1% of the participants were diagnosed with an eating disorder. Logistic regression analyses indicated the new 16-item measure and Fear of Getting Fat, significantly predicted an ED diagnosis that did not include avoidant restrictive food intake disorder (ARFID) and Social Pressure to Gain Weight significantly predicted a diagnosis of ARFID

Effect of Human Disturbance on Small Mammal Communities in Itasca State Park, Minnesota

We determined effects of different levels of human disturbance on small mammal richness and relative abundance from live-trapping data obtained in Itasca State Park in northwestern Minnesota. We developed a quantitative measure of human disturbance based on disturbance units and trapped small mammals on three study sites, each reflecting a different level of disturbance. Our data revealed that small mammal diversity decreased with increasing human disturbance. Amount of ground cover and litter depth also appeared to be important in explaining differences in the demographic patterns of small mammals among sites

Prdx1 inhibits tumorigenesis via regulating PTEN/AKT activity

It is widely accepted that reactive oxygen species (ROS) promote tumorigenesis. However, the exact mechanisms are still unclear. As mice lacking the peroxidase peroxiredoxin1 (Prdx1) produce more cellular ROS and die prematurely of cancer, they offer an ideal model system to study ROS-induced tumorigenesis. Prdx1 ablation increased the susceptibility to Ras-induced breast cancer. We, therefore, investigated the role of Prdx1 in regulating oncogenic Ras effector pathways. We found Akt hyperactive in fibroblasts and mammary epithelial cells lacking Prdx1. Investigating the nature of such elevated Akt activation established a novel role for Prdx1 as a safeguard for the lipid phosphatase activity of PTEN, which is essential for its tumour suppressive function. We found binding of the peroxidase Prdx1 to PTEN essential for protecting PTEN from oxidation-induced inactivation. Along those lines, Prdx1 tumour suppression of Ras- or ErbB-2-induced transformation was mediated mainly via PTEN