Effects of exposure of mice to hindlimb unloading on leukocyte subsets and sympathetic nervous system activity

The hindlimb unloading (HU) rodent model was developed to simulate some of the aspects of spaceflight conditions. Our previous studies showed that exposure to HU for 48 h (h) followed by bacterial challenge, reduces the ability of mice to resist infection. The purpose of this study was to investigate the physiological changes in mice during the 48 h of exposure to HU to understand the mechanisms involved in the increased susceptibility to infection observed in mice subjected to these conditions. Female Swiss Webster mice were hindlimb-unloaded during 48 h. Blood samples, spleen and peritoneal cells were removed before and after 18 or 48 h of HU-exposure. Leukocyte subset analysis was performed in spleen and peritoneal cells by flow cytometry, and catecholamine levels were measured in plasma and whole spleen by a catecholamine enzyme immunoassay. Catecholamine levels measured in plasma and spleen were significantly greater in mice exposed to HU compared to control. This increase coincided with significant reductions in spleen size in the HU group. Flow cytometric analyses showed a significant reduction of splenic CD19 + B-cells and NK1.1+ cells in mice exposed to HU with a concomitant increase in T-cells. These results suggest that exposure to HU increases the activity of the sympathetic nervous system (SNS) and induces lymphocyte sub-population changes that may contribute to the deregulation of immunity seen in mice exposed to HU and, more importantly may predispose the otherwise healthy host to the subsequent reduced ability to resist infections.     

La réception juridique de l’incertitude médicale

As regards medical responsibility, the proof of an unquestionable causal link between the damage and the fault of the expert are made difficult in the presence of uncertainties related to the etiology of certain pathologies. The article raises the question of the reception of this uncertainty by the judge and the legislator, and wonders in particular about the founded good of the recourse to law and judicial presumptions within the framework of the dispute of the victims of multiple sclerosis developed following vaccination against hepatitis B.     

Parental Engagement and Barriers to Participation in a Community-Based Preventive Intervention

This study examined parent characteristics and barriers to participation in a community-based preventive intervention with a sample of 201 parents from low-income and predominantly ethnic minority backgrounds. Person-centered analyses revealed five subgroups of parents who demonstrated variability in their parent characteristics, which included psychological resources and level of parental involvement in education. Group membership was associated with differences in school involvement and use of the psychoeducational intervention at home, after accounting for the number of barriers to engagement. For the intervention attendance variable, greater number of barriers was associated with decreased attendance only for parents in the resilient subgroup and the psychologically distressed subgroup. Attendance remained constant across levels of barriers for the other three subgroups of parents. The results of the study inform theory and practice regarding how to tailor preventive interventions to accommodate subgroups of parents within populations that experience barriers to accessing mental health services.     

Effect of Client and Counselor Ethnicity on Preference for Counselor Disclosure

Preferences for counselor self‐disclosure based on the ethnicity of both the respondent and the counselor were examined for African American and Caucasian students. Results suggested that respondent ethnicity affected preferences for certain types of information about the counselor (personal feelings, sexual issues, professional issues, and success/failure) and that there were interaction (respondent by counselor ethnicity) effects on preference for disclosure in other areas (interpersonal relationships and success/failure). Implications for research and practice are discussed.     

Selective attention and inhibitory deficits in ADHD: Does subtype or comorbidity modulate negative priming effects?

Selective attention has durable consequences for behavior and neural activation. Negative priming (NP) effects are assumed to reflect a critical inhibitory component of selective attention. The performance of adolescents with Attention Deficit/Hyperactivity Disorder (ADHD) was assessed across two conceptually based NP tasks within a selective attention procedure. Comorbidity (non-comorbid ADHD vs. comorbid ADHD) and subtype (ADHD combined vs. ADHD inattentive) were considered key issues. Results found NP effects to differ as a function of comorbidity but not subtype. Findings are discussed in light of functional neuroimaging evidence for neuronal enhancement for unattended stimuli relative to attended stimuli that strongly complements an inhibitory-based explanation for NP. Implications for the ‘AD’ in ADHD and contemporary process models of the disorder are considered.     

Emergence of attributional style and its relation to depressive symptoms

The development of depressive attributional style (AS) and its role as a cognitive diathesis for depression were examined in children and adolescents (Grades 2-9). In a 4-wave longitudinal study of 3 overlapping age cohorts, AS, negative life events, and depressive symptoms were evaluated every 12 months. Consistency of children's attributions across situations was moderately high at all ages. The cross-sectional structure of AS changed with age, as stability became a more salient aspect of AS than internality and globality. The structure of AS also changed, becoming more traitlike as children grew older. In longitudinal analyses, evidence of a Cognitive Diathesis x Stress interaction did not emerge until Grades 8 and 9, suggesting that AS may not serve as a diathesis for depression at younger ages. Results suggest that attributional models of depression may require modification before they are applied across developmental levels.     

Social presence effects on the stroop task: Boundary conditions and an alternative account

Two studies investigated boundary conditions of an effect of social presence on the Stroop task and its interpretation in terms of an attentional view (P. Huguet, M. P. Galvaing, J. M. Monteil, & F. Dumas, 1999). In this view, social presence leads to attentional focusing, enhancing participants’ ability to screen out the distracting features of Stroop stimuli. As predicted, Stroop interference was found to be reduced by social presence, but an alternative account in which social presence exerts an effect on task selection received more support.     

Aging affects acquisition and reversal of reward-based associative learning

Reward-based associative learning is mediated by a distributed network of brain regions that are dependent on the dopaminergic system. Age-related changes in key regions of this system, the striatum and the prefrontal cortex, may adversely affect the ability to use reward information for the guidance of behavior. The present study investigated the effects of healthy aging on different components of reward learning, such as acquisition, reversal, effects of reward magnitude, and transfer of learning. A group of 30 young (mean age = 24.2 yr) and a group of 30 older subjects (mean age = 64.1 yr) completed two probabilistic reward-based stimulus association learning tasks. Older subjects showed poorer overall acquisition and impaired reversal learning, as well as deficits in transfer learning. When only those subjects who showed evidence of significant learning were considered, younger subjects showed equivalently fast learning irrespective of reward magnitude, while learning curves in older subjects were steeper for high compared to low reward magnitudes. Acquired equivalence learning, which requires generalization across stimuli and transfer of learned contingencies to new stimuli, was mildly impaired in older subjects.