CRF binding protein activity in the hypothalamic paraventricular nucleus is essential for stress adaptations and normal maternal behaviour in lactating rats

To ensure the unrestricted expression of maternal behaviour peripartum, activity of the corticotropin-releasing factor (CRF) system needs to be minimised. CRF binding protein (CRF-BP) might be crucial for this adaptation, as its primary function is to sequester freely available CRF and urocortin1, thereby dampening CRF receptor (CRF-R) signalling. So far, the role of CRF-BP in the maternal brain has barely been studied, and a potential role in curtailing activation of the stress axis is unknown. We studied gene expression for CRF-BP and both CRF-R within the paraventricular nucleus (PVN) of the hypothalamus. In lactating rats, Crh-bp expression in the parvocellular PVN was significantly higher and Crh-r1 expression in the PVN significantly lower compared to virgin rats. Acute CRF-BP inhibition in the PVN with infusion of CRF(6-33) increased basal plasma corticosterone concentrations under unstressed conditions in dams. Furthermore, while acute intra-PVN infusion of CRF increased corticosterone secretion in virgin rats, it was ineffective in vehicle (VEH)-pre-treated lactating rats, probably due to a buffering effect of CRF-BP. Indeed, pre-treatment with CRF(6-33) reinstated a corticosterone response to CRF in lactating rats, highlighting the critical role of CRF-BP in maintaining attenuated stress reactivity in lactation. To our knowledge, this is the first study linking hypothalamic CRF-BP activity to hypothalamic-pituitary-adrenal axis regulation in lactation. In terms of behaviour, acute CRF-BP inhibition in the PVN under non-stress conditions reduced blanket nursing 60 min and licking/grooming 90 min after infusion compared to VEH-treated rats, while increasing maternal aggression towards an intruder. Lastly, chronic intra-PVN inhibition of CRF-BP strongly reduced maternal aggression, with modest effects on maternal motivation and care. Taken together, intact activity of the CRF-BP in the PVN during the postpartum period is essential for the dampened responsiveness of the stress axis, as well as for the full expression of appropriate maternal behaviour.

Dysfunctions of brain oxytocin signaling: Implications for poor mothering

Good mothering has profound impact on both the mother's and the young's well-being. Consequently, experiencing inadequate maternal care - or even neglect - in the first stages of life is a major risk factor for the development of psychiatric disorders, and even for poor parenting towards the future offspring. Thus, understanding the neurobiological basis of maternal neglect becomes crucial. Along with other neurotransmitters and neuropeptides, oxytocin (OXT) has long been known as one of the main modulators of maternal behavior. In rodents, disruptions of central OXT transmission have been associated with poor maternal responses, like impaired onset of nursing behaviors, and reduced care and defense of the pups. Importantly, such behavioral and molecular deficits can be transmitted through generations, creating a vicious circle of low-quality maternal behavior. Similarly, evidence from human studies shows that OXT signaling is defective in conditions of inadequate mothering and child neglect. On those premises, this review aims at providing a comprehensive overview of animal and human studies linking perturbed OXT transmission to poor maternal behavior. Considering the important fallouts of inadequate maternal responses, we believe that unraveling the alterations in OXT transmission might provide useful insights for a better understanding of maternal neglect and, ultimately, for future intervention approaches.

Psychosocial predictors of binge-drinking residual harm in adolescence and young adulthood: Findings from the Australian Temperament Project

AIMS

We examine the extent to which adolescent and young adult psychosocial factors are associated with variation in the experience of common types of harm (e.g., injuries, violence, sexual regrets) with respect to binge-drinking frequency - termed residual harm.

METHODS

Data were from the Australian Temperament Project, a population-based cohort study that has followed a sample of young Australians from infancy to adulthood since 1983. The current sample comprised 1,081 (565 women). Residual harm was operationalised by saving residuals from models regressing number of alcohol harms onto binge-drinking frequency at each of 5 waves, two in adolescence (15-16 and 17-18 years) and three in young adulthood (19-20, 23-24, and 27-28 years). Psychosocial factors (mental health, social skills, quality of parent and peer relationships) were assessed prior to binge drinking in early adolescence (13-14 years) and then again in young adulthood (19-20 years).

RESULTS

Adolescent predictors of decreased residual harm were lower depressive symptoms, and higher cooperation, self-control, and peer and parent attachment. Young adult predictors of decreased residual harm were lower depressive, anxiety, and stress symptoms and peer and parent negative appraisal, and higher responsibility, and peer and parent emotional support. Associations were evident in males and females, although the strength of some associations diminished with age.

CONCLUSIONS

Adolescents and young adults with better mental health, social skills, and relationship quality experienced less harm with respect to their binge-drinking frequency. Future research should examine the potential of investment in strength-based interventions for young people.

Exposure to Prenatal Stress Is Associated With an Excitatory/Inhibitory Imbalance in Rat Prefrontal Cortex and Amygdala and an Increased Risk for Emotional Dysregulation

Epidemiological studies have shown that environmental insults and maternal stress during pregnancy increase the risk of several psychiatric disorders in the offspring. Converging lines of evidence from humans, as well as from rodent models, suggest that prenatal stress (PNS) interferes with fetal development, ultimately determining changes in brain maturation and function that may lead to the onset of neuropsychiatric disorders. From a molecular standpoint, transcriptional alterations are thought to play a major role in this context and may contribute to the behavioral phenotype by shifting the expression of genes related to excitatory and inhibitory (E/I) transmission balance. Nevertheless, the exact neurophysiological mechanisms underlying the enhanced vulnerability to psychopathology following PNS exposure are not well understood. In the present study, we used a model of maternal stress in rats to investigate the distal effects of PNS on the expression of genes related to glutamatergic and GABAergic neurotransmissions. We inspected two critical brain regions involved in emotion regulation, namely, the prefrontal cortex (PFC) and the amygdala (AMY), which we show to relate with the mild behavioral effects detected in adult rat offspring. We observed that PNS exposure promotes E/I imbalance in the PFC of adult males only, by dysregulating the expression of glutamatergic-related genes. Moreover, such an effect is accompanied by increased expression of the activity-dependent synaptic modulator gene Npas4 specifically in the PFC parvalbumin (PV)-positive interneurons, suggesting an altered regulation of synapse formation promoting higher PV-dependent inhibitory transmission and increased overall circuit inhibition in the PFC of males. In the AMY, PNS more evidently affects the transcription of GABAergic-related genes, shifting the balance toward inhibition. Collectively, our findings suggest that the E/I dysregulation of the PFC-to-AMY transmission may be a long-term signature of PNS and may contribute to increase the risk for mood disorder upon further stress.

Long-lasting effects of prenatal stress on HPA axis and inflammation: A systematic review and multilevel meta-analysis in rodent studies

Exposure to prenatal stress (PNS) can lead to long-lasting neurobiological and behavioral consequences for the offspring, which may enhance the susceptibility for mental disorders. The hypothalamus-pituitary-adrenal (HPA) axis and the immune system are two major factors involved in the stress response. Here, we performed a systematic review and meta-analysis of rodent studies that investigated the effects of PNS exposure on the HPA axis and inflammatory cytokines in adult offspring. Our analysis shows that animals exposed to PNS display a consistent increase in peripheral corticosterone (CORT) levels and central corticotrophin-releasing hormone (CRH), while decreased levels of its receptor 2 (CRHR2). Meta-regression revealed that sex and duration of PNS protocol are covariates that moderate these results. There was no significant effect of PNS in glucocorticoid receptor (GR), CRH receptor 1 (CRHR1), pro- and anti-inflammatory cytokines. Our findings suggest that PNS exposure elicits long-lasting effects on the HPA axis function, providing an important tool to investigate in preclinical settings key pathological aspects related to early-life stress exposure. Furthermore, researchers should be aware of the mixed outcomes of PNS on inflammatory markers in the adult brain.

Anti-Stress Properties of Atypical Antipsychotics

Stress exposure represents a major environmental risk factor for schizophrenia and other psychiatric disorders, as it plays a pivotal role in the etiology as well as in the manifestation of disease symptomatology. It may be inferred that pharmacological treatments must be able to modulate the behavioral, functional, and molecular alterations produced by stress exposure to achieve significant clinical outcomes. This review aims at examining existing clinical and preclinical evidence that supports the ability of atypical antipsychotic drugs (AAPDs) to modulate stress-related alterations. Indeed, while the pharmacodynamic differences between AAPDs have been extensively characterized, less is known on their ability to regulate downstream mechanisms that are critical for functional recovery and patient stabilization. We will discuss stress-related mechanisms, spanning from neuroendocrine function to inflammation and neuronal plasticity, which are relevant for the manifestation of schizophrenic symptomatology, and we will discuss if and how AAPDs may interfere with such mechanisms. Considering the impact of stress in everyday life, we believe that a better understanding of the potential effects of AAPDs on stress-related mechanisms may provide novel and important insights for improving therapeutic strategies aimed at promoting coping mechanisms and enhancing the quality of life of patients affected by psychiatric disorders.

A comparison of longitudinal modelling approaches: Alcohol and cannabis use from adolescence to young adulthood

BACKGROUND

Modelling trajectories of substance use over time is complex and requires judicious choices from a number of modelling approaches. In this study we examine the relative strengths and weakness of latent curve models (LCM), growth mixture modelling (GMM), and latent class growth analysis (LCGA).

DESIGN

Data were drawn from the Australian Temperament Project, a 36-year-old community-based longitudinal study that has followed a sample of young Australians from infancy to adulthood across 16 waves of follow-up since 1983. Models were fitted on past month alcohol use (n = 1468) and cannabis use (n = 549) across six waves of data collected from age 13-14 to 27-28 years.

FINDINGS

Of the three model types, GMMs were the best fit. However, these models were limited given the variance of numerous growth parameters had to be constrained to zero. Additionally, both the GMM and LCGA solutions had low entropy. The negative binomial LCMs provided a relatively well-fitting solution with fewer drawbacks in terms of growth parameter estimation and entropy issues. In all cases, model fit was enhanced when using a negative binomial distribution.

CONCLUSIONS

Substance use researchers would benefit from adopting a complimentary framework by exploring both LCMs and mixture approaches, in light of the relative strengths and weaknesses as identified. Additionally, the distribution of data should inform modelling decisions.

Shyness Ratings: Stability and Correlates in Early Childhood

This study explores the stability and correlates of shyness from infancy to 6 years of age using five sets of data from a large representative sample. Included in each set are maternal ratings on a temperament dimension named Approach which assesses reactions to new people and situations, and is the measure of shyness employed here. Two issues are examined: (1) the stability of shyness as revealed by log-linear analyses, in comparison to other temperamental attributes, and when comparing extreme groups to those with moderate scores; (2) the correlates of shyness in infancy and at 5-6 years. The results suggest that the stability of shyness from 1-2 years onwards is moderate, and similar in level and patterning to other temperamental attributes. Comparisons of four subgroups differing on shyness indicate differences on other temperamental and behavioural characteristics; shyness was related to general "difficultness" in infancy, but at 5-6 years was associated with the presence of internalising problems and the absence of externalising problems.

Role of Different Solvents on the Purification of As-Synthesized Nano-Ce(1-x)Gd(x)O(2-d) Powders

Ceria and rare earth-doped ceria powders have important applications in catalysis, gas sensoring, and electronics. Even if many authors report different methods for the synthesis of nano-sized doped-ceria only few of them give information about the necessary washing processes for the powder purification. The organics adsorbed on the as-synthesized particles surface strongly affect, in fact, the properties of the powder. In this work, CeO2 and Ce(1-x)Gd(x)O(2-d) (x = 0.10, 0.20, 0.30) solid solutions were produced by polyol microwave assisted method. The amount of synthesis residues adsorbed on the as-synthesized powders was firstly evaluated. The purification ability of different solvents on the as-synthesized Ce0.80Gd0.20O190 was, then, accurately studied in order to obtain a clean powder without the need of any thermal treatments. The study shows that water purification allows to reduce the amount of the residues of synthesis leading to the production of nano-particles with a mono-dispersed distribution of dimensions.

On the neglecting of higher-order cumulants in EXAFS data analysis

The cumulant expansion is one of the most powerful and useful methods for EXAFS data analysis, in which the higher-order cumulants allow to consider deviations from a simple Gaussian distribution. In this work, analytical expressions have been derived to show the effects of neglecting higher-order cumulants in EXAFS analysis by the ratio method. The errors in the best-fitting procedure owing to the omission of the higher-order cumulants, as well as of the coordination number, can be determined.

Correlation between I-Ag distance and ionic conductivity in AgI fast-ion-conducting glasses

A large number of AgI-based fast-ion-conducting glasses have been investigated by K-iodine extended x-ray absorption fine structure spectroscopy (EXAFS) measurements at liquid nitrogen temperature. A general correlation between the I-Ag distance measured by EXAFS and the glass activation energy for dc ionic conductivity has been found out: glasses with longer I-Ag distances display higher ionic conductivity, independently from the chemical composition of their host glassy matrix. This behavior can be related to the progressive increase of the "pathway volume" for ionic conduction.

On the Einstein model for EXAFS parallel and perpendicular mean-square relative displacements

The correlated Einstein model for EXAFS parallel and perpendicular mean-square relative displacements (MSRDs) is discussed. By means of dynamical simulations on different crystalline structures, the error owing to the Einstein-fit model on the EXAFS MSRDs is estimated as a function of the standard deviation of the density of vibrational states. This error should be taken into account to improve the accuracy of the MSRDs.

Isotopic effect in extended x-ray-absorption fine structure of germanium

Extended x-ray absorption fine structure has been measured on two powdered samples of (70)Ge and (76)Ge as a function of temperature from 20 to 300 K. The effect of isotopic mass difference on the amplitude of relative atomic vibrations is neatly evidenced by the temperature dependence of the difference of Debye-Waller factors. The isotopic effect is also detected on the difference of nearest-neighbor average ineratomic distances, thanks to a resolution better than 10 fm.

No interaction between the serotonin transporter polymorphism (5-HTTLPR) and childhood adversity or recent stressful life events on symptoms of depression: results from two community surveys

In this study we investigated interactions between the 5-HTTLPR genotype and environmental risk factors (G x E) on symptoms of depression in two large Australian community samples of adolescents and young adults. We postulated that a significant interaction between the 5-HTTLPR genotype and environmental risk factors of childhood adversity or stressful life events on symptoms of depression would be observed in subjects with at least one short allele (s/l or s/s) compared with subjects with no short alleles (l/l). We did not find significant G x E interactions between the 5-HTTLPR genotype and recent stressful life events or childhood adversity on symptoms of depression in our sample populations. However, we did find adolescents aged 17-18 years homozygous for the long allele (l/l) and exposed to persistently high levels of family adversity over a 6-year period were at a greater risk of depression than subjects with the same genotype exposed to no or persistently low levels of family adversity. This interaction should be interpreted cautiously due to the small number of depressed subjects in the sample with persistently high levels of family adversity.

A cylinder-shaped double ribbon structure formed by an amyloid hairpin peptide derived from the β-sheet of murine PrP: An X-ray and molecular dynamics simulation study

A structural model of the murine PrP small beta-sheet was obtained by synthesizing the RGYMLGSADPNGNQVYYRG peptide comprising the two beta-strands 127-133 and 159-164 linked by a four-residue sequence of high turn propensity. The DPNG turn sequence is a "short circuit" replacing the original protein sequence between the two strands. This 19-residue peptide spontaneously forms very long single fibrils as observed by electron microscopy. The X-ray diffraction patterns of a partially oriented sample reveals an average arrangement of the hairpin peptides into a structure which can be geometrically approximated by an empty-core cylinder. The hairpins are oriented perpendicular to the cylinder axis and a 130 A helix period is observed. Based on X-ray diffraction constraints and on more indirect general protein structure considerations, a precise and consistent fibril model was built. The structure consists of two beta-sheet ribbons wound around a cylinder and assembled into a single fibril with a hairpin orientation perpendicular to the fibril axis. Subsequent implicit and explicit solvent molecular dynamics simulations provided the final structure at atomic resolution and further insights into the stabilizing interactions. Particularly important are the zipper-like network of polar interactions between the edges of the two ribbons, including the partially buried water molecules. The hydrophobic core is not optimally compact explaining the low density of this region seen by X-ray diffraction. The present findings provide also a simple model for further investigating the sequence-stability relationship using a mutational approach with a quasi-independent consideration of the polar and apolar interactions.

Local thermal expansion in a cuprite structure: the case of Ag(2)O

The local thermal behavior of the Ag(2)O framework structure has been studied by extended x-ray absorption fine structure. The average Ag-O nearest-neighbor distance expands upon heating, while the Ag-Ag next-nearest-neighbor distance contracts. An original implementation of the cumulant analysis shows that the Ag-O expansion is a joint effect of potential anharmonicity and geometrical deformation of the Ag(4)O basic tetrahedral units. Accordingly, the negative thermal expansion of the lattice parameter in Ag(2)O cannot be explained uniquely in terms of rigid unit modes.

On the cumulant analysis of EXAFS in crystalline solids

The analysis of temperature-dependent EXAFS spectra based on the cumulant expansion is critically reviewed, seeking for accurate relations between EXAFS parameters and physical properties of crystals. The treatment is based on the distinction between the real and effective distribution of distances, and is divided into three logical steps. (a) The connection between lattice dynamics and cumulants C(n)* of the real distribution is studied and the extent of the usual approximations are numerically evaluated. Atomic vibrations perpendicular to the bond direction make the EXAFS thermal expansion larger than the crystallographic one; the difference is connected to a shift of the effective pair potential rather than to its asymmetry. Peculiar information on lattice dynamics of crystals can be obtained from accurate EXAFS measurements and their cumulant analysis. (b) The differences between cumulants of the real and effective distribution (C(n)* and C(n), respectively) are calculated for various physically realistic distributions. The largest discrepancy concerns the first cumulant: C(1)* measures the thermal expansion of the interatomic bond, while C(1) is a better estimate of the crystallographic thermal expansion. (c) The convergence properties of the cumulant series are discussed and some phenomenological procedures are suggested to monitor and possibly work out the connected failures of the cumulant method. Benefits and risks of the use of an effective pair potential are at last debated.

Investigating the conformational coupling between the transmembrane and cytoplasmic domains of a single-spanning membrane protein. A 1H-NMR study

PMP1 is a 38-residue single-spanning membrane protein whose C-terminal cytoplasmic domain, Y25-F38, is highly positively charged. The conformational coupling between the transmembrane span and the cytoplasmic domain of PMP1 was investigated from 1H-nuclear magnetic resonance data of two synthetic fragments: F9-F38, i.e. 80% of the whole sequence, and Y25-F38, the isolated cytoplasmic domain. Highly disordered in aqueous solution, the Y25-F38 peptide adopts a well-defined conformation in the presence of dodecylphosphocholine micelles. Compared with the long PMP1 fragment, this structure exhibits both native and non-native elements. Our results make it possible to assess the influence of a hydrophobic anchor on the intrinsic conformational propensity of a cytoplasmic domain.

Concerted influence of key amino acids on the lipid binding properties of a single-spanning membrane protein: NMR and mutational analysis

Finding the combinations of key amino acids involved in the interaction network underlying the interfacial features of membrane proteins would contribute to a better understanding of their sequence-structure-function relationships and the role of anionic phospholipids. To further address these questions, we performed mutational analysis associated with NMR experiments on synthetic fragments of the single-spanning membrane protein PMP1 that exhibit binding specificity for phosphatidylserine (PS). The aromatic and glutamine residues of the helix part of the PMP1 cytoplasmic domain were mutated. (1)H NMR experiments were carried out using perdeuterated DPC micelles as a membrane-like environment, in the absence and presence of small amounts of either POPC or POPS lipids. From intermolecular NOEs and chemical shift data, specific and nonspecific aspects of peptide-phospholipid interactions were distinguished. The major finding of our study is to reveal the concerted influence of a tryptophan and a glutamine residue on the interfacial conformation and lipid binding specificity of the PMP1 cytoplasmic domain.

Longitudinal predictors of behavioural adjustment in pre-adolescent children

OBJECTIVES

Longitudinal data from infancy onwards, from the Australian Temperament Project, a prospective study of the temperament and development of a large and representative sample of Victorian children, were examined to identify predictors of psychological disorder at 11-12 years of age.

METHOD

Those children scoring in the at-risk range for psychological disorder according to parents, teachers and self-reports using the Child Behaviour Questionnaire were selected at 11-12 years of age for in-depth assessment and comparison with a group of children with no history of adjustment problems. Analyses of group differences using longitudinal data gathered from infancy to 12 years focused on parent and teacher reports on child temperament and behaviour, and various facets of home and school adjustment.

RESULTS

The strongest predictors of adjustment at 12 years were previous behaviour problems, along with some specific temperament factors involving self-regulation capacities and mother's overall rating of child difficulty. Results based on parallel teacher data including peer adjustment, and social and academic competence measures were consistent with parent data.

CONCLUSIONS

Our research confirms the persistence of early appearing behaviour problems in a community sample and the longitudinal influence of temperament factors in childhood. The study supports the need for a focus on early intervention and prevention strategies in the child mental health field.

Association of a polymorphism of the dopamine transporter gene with externalizing behavior problems and associated temperament traits: a longitudinal study from infancy to the mid-teens

There have been reports that a variable number of tandem repeats (VNTR) polymorphism situated in the 3' untranslated region of the dopamine transporter gene is associated with attention-deficit hyperactivity disorder. On the basis of these findings, we predicted an association of this polymorphism with hyperactivity, other externalizing behavior problems, and related temperament traits in a general population sample. The association was investigated using children participating in a longitudinal study of childhood temperament and development. DNA was taken from 660 children who had been assessed for temperament from 4-8 months to 15-16 years, and for behavior problems from 3-4 to 15-16 years. No significant associations were found at any age. There are a number of methodological differences from earlier studies that might explain the lack of associations with hyperactivity. It is also possible that the earlier findings are not replicable.

15N NMR relaxation as a probe for helical intrinsic propensity: the case of the unfolded D2 domain of annexin I

The isolated D2 domain of annexin I is unable to adopt a tertiary fold but exhibits both native and non-native residual structures. It thus constitutes an attractive model for the investigation of dynamics of partially folded states in the context of protein folding and stability. 15N relaxation parameters of the D2 domain have been acquired at three different magnetic fields, 500, 600 and 800 MHz. This enables the estimation of the contribution of conformational exchange to the relaxation parameters on the micro- to millisecond time scale, thus providing a suitable data set for the description of motions on the pico- and nanosecond time scale. The analysis of the seven spectral densities obtained (J(0), J(50 MHz), J(60 MHz), J(80 MHz), <J(500 MHz)>, <J(600 MHz)>, <J(800 MHz)>) provides complementary and meaningful results on the conformational features of the D2 domain structure previously depicted by chemical shift and NOE data. Especially, residual helix segments exhibit distinct dynamical behaviors that are related to their intrinsic helical propensity. Beside the spectral density analysis, a series of models derived from the Lipari and Szabo model-free approach are investigated. Two models containing three parameters are able to reproduce equally well the experimental data within experimental errors but provide different values of order parameters and correlation times. The inability to find a unique model to describe the data emphasizes the difficulty to use and interpret the model-free parameters in the case of partially or fully unfolded proteins consisting of a wide range of interconverting conformers.

PMP1 18-38, a yeast plasma membrane protein fragment, binds phosphatidylserine from bilayer mixtures with phosphatidylcholine: a (2)H-NMR study

PMP1 is a 38-residue plasma membrane protein of the yeast Saccharomyces cerevisiae that regulates the activity of the H(+)-ATPase. The cytoplasmic domain conformation results in a specific interfacial distribution of five basic side chains, thought to strongly interact with anionic phospholipids. We have used the PMP1 18-38 fragment to carry out a deuterium nuclear magnetic resonance ((2)H-NMR) study for investigating the interactions between the PMP1 cytoplasmic domain and phosphatidylserines. For this purpose, mixed bilayers of 1-palmitoyl, 2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl, 2-oleoyl-sn-glycero-3-phosphoserine (POPS) were used as model membranes (POPC/POPS 5:1, m/m). Spectra of headgroup- and chain-deuterated POPC and POPS phospholipids, POPC-d4, POPC-d31, POPS-d3, and POPS-d31, were recorded at different temperatures and for various concentrations of the PMP1 fragment. Data obtained from POPS deuterons revealed the formation of specific peptide-POPS complexes giving rise to a slow exchange between free and bound PS lipids, scarcely observed in solid-state NMR studies of lipid-peptide/protein interactions. The stoichiometry of the complex (8 POPS per peptide) was determined and its significance is discussed. The data obtained with headgroup-deuterated POPC were rationalized with a model that integrates the electrostatic perturbation induced by the cationic peptide on the negatively charged membrane interface, and a "spacer" effect due to the intercalation of POPS/PMP1f complexes between choline headgroups.

Association of a functional polymorphism of the serotonin transporter gene with anxiety-related temperament and behavior problems in children: a longitudinal study from infancy to the mid-teens

A polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) has been associated with anxiety-related personality traits in adults. Initial studies showed that the short allele was associated with higher neuroticism, anxiety and harm avoidance. However, most attempts to replicate these findings have been negative. Because the association of candidate polymorphisms with behavioral traits may vary with stage of development, we investigated the association using participants in a longitudinal study of childhood temperament. DNA was available for 660 children who had been assessed for temperament from 4-8 months to 15-16 years, and for behaviour problems from 3-4 years to 15-16 years. No significant associations were found at most ages. However, at ages 13-14 years and 15-16 years, the long/long genotype was associated with higher anxiety. These findings do not support an association of the short allele with anxiety-related traits in early life.

Does shy-inhibited temperament in childhood lead to anxiety problems in adolescence?

OBJECTIVE

To assess the relationships between shy-inhibited temperament in childhood and anxiety problems in early adolescence using a prospective, longitudinal data set from a large community sample.

METHOD

Relationships between shyness ratings on age-appropriate temperament scales and anxiety problems were analyzed, looking both forward and backward in time from infancy to adolescence.

RESULTS

Forty-two percent of children rated as shy on 6 or more occasions over 8 surveys in childhood had anxiety problems in adolescence, compared with 11% who were never shy. Persistence of shyness and its presence in middle childhood increased risk for anxiety. A highly reactive temperament added to shyness did not increase the risk for anxiety. Few children with an anxiety diagnosis in early adolescence had a history of shyness.

CONCLUSIONS

Prediction from childhood shyness to adolescent anxiety disorder is modest but clinically meaningful in a community sample. However, most shy children did not develop an anxiety disorder and most adolescents with anxiety disorders had not been especially shy.

A longitudinal study of the role of childhood temperament in the later development of eating concerns

OBJECTIVE

This study examined the relationship between childhood temperament and the later development of eating and body concerns in early adolescent children.

METHOD

The Australian Temperament Project has followed a cohort of children from birth, assessing temperament factors such as Negative Emotionality, Persistence, Approach/Withdrawal, and Activity. Using a longitudinal design, the study reports on the relationship between temperament measured from infancy onward and eating and body concerns at 12-13 years of age. Participants (597 girls, 631 boys) completed the Eating Disorders Inventory subscales Drive For Thinness, Body Dissatisfaction, and Bulimia, and an estimate of their current size. Parents described their child's temperament and body size.

RESULTS

High Negative Emotionality and low Persistence were the factors most associated with risk status over time, particularly in girls.

DISCUSSION

While it is unlikely that temperamental characteristics per se lead to disordered eating, it is argued that in combination with other risk factors, certain temperamental characteristics may increase vulnerability.

Dimensions of early childhood behavior problems: stability and predictors of change from 18 to 30 months

The prevalence, structure, stability, and predictors of change in early behavior problems were examined in a population-based sample of Norwegian children at 18 and 30 months of age (N = 750). A clear factor structure involving four dimensions emerged at both assessment times: Two factors were characterized by externalizing behaviors and were labeled Social Adjustment and Overactive-Inattentive; one factor tapped internalizing problems and was labeled Emotional Adjustment; and the fourth, related to general immaturity, was labeled Regulation. Specific patterns of child and family risk factors were associated with stability and change over the two time points for each factor. Children with stable problems had the most problematic characteristics on all significant predictors, followed by children with problems at one, but not both, time points. The data suggest that it is possible to identify risk factors for stable problems at 18 months, allowing some prediction of those children whose problems will persist over early childhood. Since specific risk factors emerged for specific types of behavior problems, the results may provide some much-needed guidance to early intervention efforts.

Localization of Bud2p, a GTPase-activating protein necessary for programming cell polarity in yeast to the presumptive bud site

Yeast cells of different cell type exhibit distinct budding patterns that reflect the organization of the actin cytoskeleton. Bud1p (Rsr1p), a Ras-like GTPase, and Bud2p, a GTPase-activating protein for Bud1p, are essential for proper budding pattern. We show that Bud2p is localized at the presumptive bud site in G(1) cells in all cell types and that this localization is independent of Bud1p. Bud2p subsequently localizes to the mother-bud neck after bud emergence; this localization depends on the integrity of the septins. These observations indicate that Bud2p becomes positioned in G(1) cells by recognizing cell type-specific landmarks at the presumptive bud site.

Psychological disorders and their correlates in an Australian community sample of preadolescent children

The nature and correlates of psychological disorders of preadolescent children from the longitudinal Australian Temperament Project (ATP) are reported. Almost half of the children identified via checklists completed by mothers, teachers, and the children themselves as being in the at-risk range for disorder received a DSM-III-R diagnosis. Nine per cent of comparison, or low-risk, children also received a diagnosis. Internalising disorders were the most common, and 44% of cases had multiple problems. Children rated as problematic by all three informants or by child plus teacher were the most likely to receive a diagnosis. The at-risk group had more difficult temperament, poorer family and peer relationships, lower levels of social skills, and were of lower SES than the comparison group. There were minimal differences on these variables between at-risk children who did, or did not, receive a DSM-III-R diagnosis. It is argued that especially for boys, checklists from multiple informants are effective tools for identifying clinically significant disorders.

Relationships between learning difficulties and psychological problems in preadolescent children from a longitudinal sample

OBJECTIVES

To examine the relationships between learning difficulties and behavior problems in preadolescent children both concurrently and longitudinally, using data from the Australian Temperament Project, and to examine associations between DSM-diagnosed disorders and types of learning difficulties.

METHOD

Clinical and comparison groups of 11- to 12-year-old children were assessed on behavioral and learning indices and completed a structured diagnostic interview. Longitudinal data were available from earlier surveys of the development of these children.

RESULTS

Children in the clinical group were disadvantaged on all learning and behavioral indices, and their problems in many cases had been evident from 7 to 8 years of age. There were specific associations between types of learning difficulties and both internalizing and externalizing disorders. Numeracy difficulties were strongly associated with DSM diagnoses for both boys and girls, and externalizing problems tended to co-occur with a combination of learning problems.

CONCLUSIONS

Behavioral maladjustment in many domains is strongly associated with learning difficulties even after intelligence and socioeconomic factors are controlled. The odds ratios for persistence of difficulties throughout elementary school are extremely high for children with clinical problems.

Dodecylphosphocholine micelles as a membrane-like environment: new results from NMR relaxation and paramagnetic relaxation enhancement analysis

To further examine to what extent a dodecyl-phosphocholine (DPC) micelle mimics a phosphatidylcholine bilayer environment, we performed 13C, 2H, and 31P NMR relaxation measurements. Our data show that the dynamic behavior of DPC phosphocholine groups at low temperature (12 degrees C) corresponds to that of a phosphatidylcholine interface at high temperature (51 degrees C). In the presence of helical peptides, a PMP1 fragment, or an annexin fragment, the DPC local dynamics are not affected whereas the DPC aggregation number is increased to match an appropriate area/volume ratio for accommodating the bound peptides. We also show that quantitative measurements of paramagnetic relaxation enhancements induced by small amounts of spin-labeled phospholipids on peptide proton signals provide a meaningful insight on the location of both PMP1 and annexin fragments in DPC micelles. The paramagnetic contributions to the relaxation were extracted from intra-residue cross-peaks of NOESY spectra for both peptides. The location of each peptide in the micelles was found consistent with the corresponding relaxation data. As illustrated by the study of the PMP1 fragment, paramagnetic relaxation data also allow us to supply the missing medium-range NOEs and therefore to complete a standard conformational analysis of peptides in micelles.

Expression, purification, and characterization of Sss1p, an essential component of the yeast Sec61p protein translocation complex

Sss1p, a 8.9-kDa membrane protein, is an essential component of the protein translocation complex involved in the transport of secretory proteins across the Saccharomyces cerevisiae endoplasmic reticulum membrane. In order to determine the high resolution structure of Sss1p by NMR, we have undertaken its overexpression and purification. We first inserted the yeast SSS1 gene into the pGEX-2T plasmid expression vector. Sss1p was expressed as fusions with Schistosoma japonica glutathione S-transferase (GST-Sss1p) in MC1061 Escherichia coli cells. Maximum yield of GST-Sss1p was obtained from cells harvested 2 h after induction at 37 degreesC in Luria broth medium. GST-Sss1p was found associated predominantly with the membrane pool and was readily extracted with Triton X-100. Detergent-solubilized GST-Sss1p was isolated by adsorption on glutathione-agarose beads. Sss1p was released from its GST carrier by cleavage with thrombin and its recovery was maximized by addition of dodecyl maltoside. Desorbed Sss1p was loaded on a high-performance liquid chromatography hydroxyapatite column equilibrated in phosphate buffer supplemented with dodecyl maltoside and the fractions containing Sss1p were subsequently purified to homogeneity by reverse-phase chromatography on a C4 column. The entire purification protocol can be completed in 5-6 h and yields about 0.4 mg of Sss1p per gram of transformed cells. CD and preliminary 1H NMR experiments show that purified Sss1p solubilized in SDS micelles is very stable and adopts a helical secondary structure.

A conformational equilibrium in a protein fragment caused by two consecutive capping boxes: 1H-, 13C-NMR, and mutational analysis

The conformational properties of an 18 residues peptide spanning the entire sequence, L1KTPA5QFDAD10ELRAA15MKG, of the first helix (A-helix) of domain 2 of annexin I, were thoroughly investigated. This fragment exhibits several singular features, and in particular, two successive potential capping boxes, T3xxQ6 and D8xxE11. The former corresponds to the native hydrogen bond network stabilizing the alpha helix N-terminus in the protein; the latter is a non-native capping box able to break the helix at residue D8, and is observed in the domain 2 partially folded state. Using 2D-NMR techniques, we showed that two main populations of conformers coexist in aqueous solution. The first corresponds to a single helix extending from T3 to K17. The second corresponds to a broken helix at residue Ds. Four mutants, T3A, F7A, D8A, and E11A, were designed to further analyze the role of key amino acids in the equilibrium between the two ensembles of conformers. The sensitivity of NMR parameters to account for the variations in the populations of conformers was evaluated for each peptide. Our data show the delta13Calpha chemical shift to be the most relevant parameter. We used it to estimate the population ratio in the various peptides between the two main ensembles of conformers, the full helix and the broken helix. For the WT, E11A, and F7A peptides, these ratios are respectively 35/65, 60/40, 60/40. Our results were compared to the data obtained from helix/coil transition algorithms.

Exploring the folding pathways of annexin I, a multidomain protein. I. non-native structures stabilize the partially folded state of the isolated domain 2 of annexin I

Proteins of the annexin family constitute very attractive models because of their four approximately 70 residue domains, D1 to D4, exhibiting an identical topology comprising five helix segments with only a limited sequence homology of approximately 30%. We focus on the isolated D2 domain, which is only partially folded. A detailed analysis of this equilibrium partially folded state in aqueous solution and micellar solution using 15N-1H multidimensional NMR is presented. Comparison of the residual structure of the entire domain with that of shorter fragments indicates the presence of long-range transient hydrophobic interactions that slightly stabilize the secondary structure elements. The unfolded domain tends to behave as a four-helix, rather than as a five-helix domain. The ensemble of residual structures comprises: (i) a set of native structures consisting of three regions with large helix populations, in rather sharp correspondence with A, B and E helices, and a small helix population in the second part of the C helix; (ii) a set of non-native local structures corresponding to turn-like structures stabilized by several side-chain to side-chain interactions and helix-disruptive side-chains to backbone interactions. Remarkably, residues involved in these local non-native interactions are also involved, in the native structure, in structurally important non-local interactions. During the folding process of annexin I, the local non-native interactions have to switch to native long-range interactions. This structural switch reveals the existence of a sequence-encoded regulation of the folding pathways and kinetics, and emphasizes the key role of the non-native local structures in this regulation.

Exploring the folding pathways of annexin I, a multidomain protein. II. Hierarchy in domain folding propensities may govern the folding process

In the context of exploring the relationship between sequence and folding pathways, the multi-domain proteins of the annexin family constitute very attractive models. They are constituted of four approximately 70-residue domains, named D1 to D4, with identical topologies but only limited sequence homology of approximately 30%. The domains are organized in a pseudochiral circular arrangement. Here, we report on the folding propensity of the D1 domain of annexin I obtained from overexpression in Escherichia coli. Unlike the D2 domain, which is only partially folded, the isolated D1 domain exhibits autonomous refolding in pure aqueous solution. Similarly, the D3 domain and D2-D3 module were obtained from expression in E. coli but were found to be largely unfolded. No conclusion could be drawn for the D4 domain because it was not possible to extract it from the bacterial inclusion bodies. The data allow us to propose a plausible scenario for the annexin I folding. This working model states that firstly the D1 domain folds, and the D2 and D3 domains remain partly unfolded, facilitating the docking of the D4 domain to the D1 domain. In a second step, the D1 and D4 domains dock, and D4 may fold if already not folded. The final step starts with the stabilization of the D1-D4 module. This stabilization is crucial for allowing the non-native local interactions inside the still partially unfolded D2 domain to switch to the native long-range interactions involving D4. This switch allows the complete folding of D2 and D3. The model proposes a sequential and hierarchical process for the folding of annexin I and emphasizes the role of both native framework and non-native structures in the process.

1H- and 2H-NMR studies of a fragment of PMP1, a regulatory subunit associated with the yeast plasma membrane H(+)-ATPase. Conformational properties and lipid-peptide interactions

PMP1 is a 38-residue polypeptide associated with the yeast plasma membrane H(+)-ATPase, found to regulate the enzyme activity. To investigate the molecular basis of the PMP1 biological function, the conformational properties of a synthetic PMP1 fragment, A18-F38, comprising the predicted C-terminal cytoplasmic domain and a part of the transmembrane anchor have been studied by 1H- and 2H-NMR spectroscopies. High resolution 1H-NMR experiments showed that, in deuterated DPC micelles, the A18-G34 segment adopts a well defined helix conformation. Our data suggest that the whole PMP1 molecule forms a unique helix whose axis might be slightly tilted with respect to the bilayer normal. Protonated DPC, DMPC and DMPS were incorporated in deuterated micelles containing the PMP1 fragment for studying lipid-peptide interactions. Unusually strong and selective intermolecular NOEs between lipid chain and peptide side chain protons, especially those of the unique Trp residue, were observed. Solid state 2H-NMR experiments performed on pure deuterated POPC and mixed deuterated POPC:POPS (5:1) bilayers revealed that the PMP1 fragment specifically interacts with negatively charged PS lipids.

Structure of human annexin I: comparison of homology modelling and crystallographic experiment

A model of domain II of annexin I has been built by homology modelling using an annexin V crystal structure as a template. The method used is based on that of Summers and Karplus (J Mol Biol (1989) 210, 785-811) and involves the calculation of torsion-angle rotational energy maps to position side chains. The RMS deviation of the backbone heavy atoms between the model and a crystal structure of annexin I is 1.1 A. Similarities and differences in the experimental and model-derived side-chain rotameric conformations and hydrogen-bonding interactions are examined. It is found that whereas many of the side chains are well positioned some of those placed using the 'entropy argument' in which the broadest of the available minima are preferred, are erroneous. The domain is subjected to molecular dynamics simulation in explicit solvent. The simulations are found to 'correct' some of the side-chain rotamer positions that were poorly placed in the homology modelling. Considerable helix instability is seen in the simulations, consistent with the requirement of domain interactions for the structural integrity of the protein.

"Growing pains": clinical and behavioral correlates in a community sample

Parents of 183 children identified them as having "pain in arms, legs, or joints during the previous 12 months." This group was compared with a group of children without pains selected randomly from the rest of a 1605-member community-based cohort in a study of chronic illness. The pains were most likely to be deep seated, to involve predominantly the lower limbs, and to be described in vague, nonspecific terms. These children were significantly more likely to have recurrent abdominal pain, a negative mood, and behavior problems, and to be aggressive, anxious, and hyperactive. There were no differences between the groups on any teacher ratings of behavior, temperament, social skills, or academic achievement. We conclude that children with "growing pains" are rated by their parents, but not their teachers, as having different temperamental and behavioral profiles than controls. These data suggest a psychosocial contribution to growing pains akin to that seen with other pain syndromes.

NMR conformational study of the cytoplasmic domain of the canine Sec61 gamma protein from the protein translocation pore of the endoplasmic reticulum membrane

Conformational studies of the synthesized N-terminal cytoplasmic domain of the canine Sec61 gamma protein, an essential protein from the translocation pore of secretory proteins across the endoplasmic reticulum membrane, were performed using two-dimensional proton NMR spectroscopy. This canine domain is one of the smallest domains within the homologous protein family and may thus constitute the minimal functional structure. The peptide was solubilized in pure aqueous solution or in the presence of dodecylphosphocholine micelles mimicking a membrane-solution interface. In pure aqueous solution, the peptide is remarkably unfolded. Forming a stable complex with dodecylphosphocholine micelles, it acquires a well-defined alpha-helix-loop-alpha-helix secondary structure, with the helix, highly amphipathic, lying at the micelle surface. The loop comprising four residues is delimited by two flanking helix-capping structures, highly conserved in the whole homologous protein family. No tertiary structure, which could have been revealed by interhelix NOE contacts, was observed. From these experimental results and using general arguments based on sequence information and knowledge of peptide-membrane interactions, a structure of the entire Sec61 gamma protein in membrane bilayers is proposed.

Folding properties of an annexin I domain: a 1H-15N NMR and CD study

The annexin fold consists of four 70-residue domains with markedly homologous sequences and nearly identical structures. Each domain contains five helices designated A to E. Domain 2 of annexin I was obtained by chemical synthesis including ten specifically labeled residues and studied by 1H-15N NMR and circular dichroism (CD). In pure aqueous solution this annexin domain presents, at most, 25% of residual helix secondary structure compared to 75%-85% for the native helix content and thus does not constitute an autonomous folding unit. Dodecylphosphocholine (DPC) micelles were used to provide the annexin domain with non-specific hydrophobic interactions. The structuring effect of micelles was thoroughly investigated by CD and 1H-15N NMR. Most, but not all, of the native helix secondary structure was recovered at DPC saturation. NMR data made it possible to determine the intrinsic helix propensity hierarchy of the different helix segments of the domain: A approximately B approximately E > C, D. This hierarchy is remarkably well correlated with the location of the helices in the native protein since A, B, and E helices are those in contact with the remaining parts of the protein. This result tends to support the view that, for large proteins like annexins (35 kDa), high intrinsic secondary structure propensities, at least helix propensity, in selected protein segments is necessary for a correct folding process. As a consequence this also indicates that important information concerning the folding pathway is encoded in the protein sequence.