Differences In Biological Sensitivity Research Articles

Characterization of the functional activity of botulinum neurotoxin subtype B6.

Clostridium botulinum produces the highly potent neurotoxin, botulinum neurotoxin (BoNT), which is classified into seven serotypes (A-G); the subtype classification is confirmed by the diversity of amino acid sequences among the serotypes. BoNT from the Osaka05 strain is associated with type B infant botulism and has been classified as BoNT/B subtype B6 (BoNT/B6) by phylogenetic analysis and the antigenicity of its C-terminal heavy chain (HC ) domain. However, the molecular bases for its properties, including its potency, are poorly understood. In this study, BoNT/B6 holotoxin was purified and the biological activity and receptor binding activity of BoNT/B6 compared with those of the previously-characterized BoNT/B1 and BoNT/B2 subtypes. The derivative BoNT/B6 was found to be already nicked and in an activated form, indicating that endogenous protease production may be higher in this strain than in the other two strains. BoNT/B1 exhibited the greatest lethal activity in mice, followed by BoNT/B6, which is consistent with the sensitivity of PC12 cells. No significant differences were seen in the enzymatic activities of the BoNT/Bs against their substrate. HC /B1 and HC /B6 exhibited similar binding affinities to synaptotagmin II (SytII), which is a specific protein receptor for BoNT/B. Binding to the SytII/ganglioside complex is functionally related to the toxic action; however, the receptor recognition sites are conserved. These results suggest that the distinct characteristics and differences in biological sensitivity of BoNT/B6 may be attributable to the function of its Hc .domain.

Adolescent Conflict Appraisals Moderate the Link Between Marital Conflict and Physiological Stress Reactivity.

The goal of this study was to advance understanding of how adolescent conflict appraisals contribute uniquely, and in combination with interparental conflict behavior, to individual differences in adolescent physiological reactivity. Saliva samples were collected from 153 adolescents (52% female; ages 10-17years) before and after the Trier Social Stress Test. Saliva was assayed for cortisol and alpha-amylase. Results revealed interactive effects between marital conflict and conflict appraisals. For youth who appraised parental conflict negatively (particularly as threatening), negative marital conflict predicted dampened reactivity; for youth who appraised parental conflict less negatively, negative marital conflict predicted heightened reactivity. These findings support the notion that the family context and youth appraisals of family relationships are linked with individual differences in biological sensitivity to context.

Friendship network position and salivary cortisol levels

We employed a social network analysis approach to examine the associations between friendship network position and cortisol levels. The sample consisted of 74 first-year students (93% female, ages 22–38 years, M = 27) from a highly competitive, accelerated Nursing program. Participants completed questionnaires online, and the entire group met at one time to complete a series of sociometric nominations and donated a saliva sample. Saliva was later assayed for cortisol. Metrics derived from directed friendship nominations indexed each student's friendship network status regarding popularity, gregariousness, and degree of interconnectedness. Results revealed that (1) individuals with lower gregariousness status (i.e., lowest number of outgoing ties) had higher cortisol levels, and (2) individuals with higher popularity status (i.e., higher numbers of incoming ties) had higher cortisol levels. Popularity and gregariousness-based network status is significantly associated with hypothalamic–pituitary–adrenal axis activity. Implications for prevailing theories of the social determinants of individual differences in biological sensitivity and susceptibility to context are discussed.

113. Oxytocin receptor gene (OXTR) variation moderates affective placebo responders in fatigued breast cancer survivors: Relevance to biological sensitivity to context

Current studies suggest that A-allele carriers of the OXTR SNP rs53576 have greater social stress vulnerability. The biological sensitivity to context theory (Boyce and Ellis) suggests that high-reactivity phenotypes exhibit risk-augmenting or risk-protective responses depending on social context. We examined rs53576 allele variation on affective and placebo responses to an intervention with positive social context (touch therapy). Thirty-two fatigued breast cancer survivors received eight 60-min touch sessions over 4 weeks. Pre-post session ratings of negative affect (NA; Profile of Mood States) and expectations were assessed. DNA was amplified via PCR and pyrosequenced. There were 12 G/Gs, 19 A/Gs, 1 A/A. G/G vs. A-carriers did not differ on pre-treatment NA or expectation. A-carriers showed greater initial reductions in NA (p r > .69;.10 > p > .005 for 6/8 sessions). For A-carriers, cumulative expectation rating scores predicted NA scores at session 8, while controlling for baseline NA (β = − .70, t(df = 15) = − 2.3, p = .036). Rs53576 A-allele carriers appear more sensitive to the beneficial effects of placebo mechanisms on negative affect reduction by socially supportive intervention contexts. Results suggest that psychological and placebo responses to interventions with positive social valence may be predicted by individual differences in biological sensitivity to context.

Understanding and promoting resilience in children and youth

In a context of global concern about the consequences of stress and extreme adversities, advances in theory and methods for studying human resilience have ushered in a new era of integrative, biopsychosocial research. This review highlights recent theory, findings, and implications of resilience research on young people. Resilience research has shifted toward dynamic system models with multiple levels of interaction, including research on the neurobiology of stress and adaption, epigenetic processes, and disasters. Growing evidence indicates individual differences in biological sensitivity to negative and positive experiences, including interventions. Early experiences show enduring programming effects on key adaptive systems, underscoring the importance of early intervention. Studies of developmental cascades demonstrate spreading effects of competence and symptoms over time, with important implications for the timing and targeting of interventions. Disaster research suggests guidelines for planning to protect children in the event of large-scale trauma. Research is integrating the study of resilience across system levels, with implications for promoting positive adaptation of young people faced with extreme adversity. However, studies on neurobiological and epigenetic processes are just beginning, and more research is needed on efficacy, as well as strategic timing and targeting, of interventions.

Peer Victimization and Aggression: Moderation by Individual Differences in Salivary Cortiol and Alpha-Amylase

This research examined whether variations in salivary measures of the hypothalamic-pituitary-adrenal axis (cortisol) and autonomic nervous system (alpha amylase [sAA]) contribute to individual differences in the association between peer victimization and aggression. Children (N = 132; M age = 9.46 years, SD = 0.33) completed a measure of peer victimization, teachers rated children's aggression, and children's saliva was collected prior to, and following, participation in a laboratory-based peer-oriented social challenge task. Children rated their level of frustration at the end of the task. Results revealed that victimization interacted with cortisol and sAA measured in anticipation of the task to predict aggression; the victimization x cortisol contribution to aggression was partly mediated by children's self-reported frustration level. Victimization also was associated with heightened frustration in girls with high task-related sAA reactivity. Task-related sAA reactivity was associated with heightened aggression, but only for girls. These findings suggest that associations between peer victimization and aggression are moderated by variation in the activity of the major components of the psychobiology of stress; results are discussed in relation to theoretical models of individual differences in biological sensitivity to context.

Prenatal cocaine exposure and infant cortisol reactivity.

This study examined the effects of prenatal cocaine exposure on infant hypothalamic-pituitary-adrenal axis activity and reactivity at 7 months of infant age. Participants were 168 caregiver-infant dyads (87 cocaine exposed, 81 not cocaine exposed; 47% boys). Maternal behavior, caregiving instability, and infant growth and behavior were assessed, and children's saliva was sampled before, during, and after standardized procedures designed to elicit emotional arousal. Results revealed cocaine-exposed infants had a high amplitude trajectory of cortisol reactivity compared to non-cocaine-exposed infants. Infant gender and caregiving instability moderated this association. The findings support a dual hazard vulnerability model and have implications for evolutionary-developmental theories of individual differences in biological sensitivity to context.