Metabolomics, lipidomics and proteomics profiling of myoblasts infected with Trypanosoma cruzi after treatment with different drugs against Chagas disease

INTRODUCTION

Chagas disease, the most important parasitic infection in Latin America, is caused by the intracellular protozoan Trypanosoma cruzi. To treat this disease, only two nitroheterocyclic compounds with toxic side effects exist and frequent treatment failures are reported. Hence there is an urgent need to develop new drugs. Recently, metabolomics has become an efficient and cost-effective strategy for dissecting drug mode of action, which has been applied to bacteria as well as parasites, such as different Trypanosome species and forms.

OBJECTIVES

We assessed if the metabolomics approach can be applied to study drug action of the intracellular amastigote form of T. cruzi in a parasite-host cell system.

METHODS

We applied a metabolic fingerprinting approach (DI-MS and NMR) to evaluate metabolic changes induced by six different (candidate) drugs in a parasite-host cell system. In a second part of our study, we analyzed the impact of two drugs on polar metabolites, lipid and proteins to evaluate if affected pathways can be identified.

RESULTS

Metabolic signatures, obtained by the fingerprinting approach, resulted in three different clusters. Two can be explained by already known of mode actions, whereas the three experimental drugs formed a separate cluster. Significant changes induced by drug action were observed in all the three metabolic fractions (polar metabolites, lipids and proteins). We identified a general impact on the TCA cycle, but no specific pathways could be attributed to drug action, which might be caused by a high percentage of common metabolome between a eukaryotic host cell and a eukaryotic parasite. Additionally, ion suppression effects due to differences in abundance between host cells and parasites may have occurred.

CONCLUSION

We validated the metabolic fingerprinting approach to a complex host-cell parasite system. This technique can potentially be applied in the early stage of drug discovery and could help to prioritize early leads or reconfirmed hits for further development.

The PHF21B gene is associated with major depression and modulates the stress response

Major depressive disorder (MDD) affects around 350 million people worldwide; however, the underlying genetic basis remains largely unknown. In this study, we took into account that MDD is a gene-environment disorder, in which stress is a critical component, and used whole-genome screening of functional variants to investigate the 'missing heritability' in MDD. Genome-wide association studies (GWAS) using single- and multi-locus linear mixed-effect models were performed in a Los Angeles Mexican-American cohort (196 controls, 203 MDD) and in a replication European-ancestry cohort (499 controls, 473 MDD). Our analyses took into consideration the stress levels in the control populations. The Mexican-American controls, comprised primarily of recent immigrants, had high levels of stress due to acculturation issues and the European-ancestry controls with high stress levels were given higher weights in our analysis. We identified 44 common and rare functional variants associated with mild to moderate MDD in the Mexican-American cohort (genome-wide false discovery rate, FDR, <0.05), and their pathway analysis revealed that the three top overrepresented Gene Ontology (GO) processes were innate immune response, glutamate receptor signaling and detection of chemical stimulus in smell sensory perception. Rare variant analysis replicated the association of the PHF21B gene in the ethnically unrelated European-ancestry cohort. The TRPM2 gene, previously implicated in mood disorders, may also be considered replicated by our analyses. Whole-genome sequencing analyses of a subset of the cohorts revealed that European-ancestry individuals have a significantly reduced (50%) number of single nucleotide variants compared with Mexican-American individuals, and for this reason the role of rare variants may vary across populations. PHF21b variants contribute significantly to differences in the levels of expression of this gene in several brain areas, including the hippocampus. Furthermore, using an animal model of stress, we found that Phf21b hippocampal gene expression is significantly decreased in animals resilient to chronic restraint stress when compared with non-chronically stressed animals. Together, our results reveal that including stress level data enables the identification of novel rare functional variants associated with MDD.

Maternal Regulation of Daughters' Emotion During Conflicts From Early to Mid-Adolescence

Primary caregivers play an important role in emotion socialization. Real-time mother-daughter emotion socialization was examined in 45 mother-daughter dyads with early-adolescent daughters (age M = 11.80, SD = .27) at the first observation point. Maternal supportive emotion regulation and daughters' emotions were coded during two conflict discussions, 2 years apart. With multilevel survival analysis, the likelihood of maternal supportiveness was predicted both over time, between early and mid-adolescence, and by daughters' pubertal status. Mothers were more likely to respond to daughters' negative and positive emotions with supportiveness for daughters whose pubertal maturation occurred relatively early. Results suggest that mothers adjust their socialization of daughters' emotions according to their daughters' pubertal development.

Alterations in anxiety and social behaviour in Npas4 deficient mice following photochemically-induced focal cortical stroke

In addition to causing widespread cell death and loss of brain function, cerebral ischaemia also induces extensive neuroplasticity. In humans, stroke is often accompanied by severe cognitive and psychiatric changes that are thought to arise as a consequence of this infarct-induced remodelling. A candidate for producing these post-stroke neuropsychiatric changes is Npas4, an activity-dependent transcription factor involved in synaptic plasticity whose expression is aberrantly up-regulated following ischaemic injury. In this study we investigated the role of Npas4 in modulating these stroke-induced neuropsychiatric responses by comparing the performance of wildtype and Npas4^-/- mice in various cognitive and behavioural tasks in a photochemical model of focal cortical stroke. We show that this stroke model results in impaired spatial recognition memory and a reduction in despair-like behaviour that affect both genotypes to a similar degree. Moreover, mice lacking Npas4 also show differences in some aspects of post-stroke sociability and anxiety. Specifically, we show that while stroke had no effect on anxiety levels in wildtype mice, Npas4^-/- mice became significantly more anxious following stroke. In addition, Npas4^-/- mice retained a greater level of sociability in the acute post-stroke period in comparison to their wildtype littermates. Thus, our findings suggest that Npas4 may be involved in post-stroke psychiatric changes related to anxiety and sociability.

The Dialogical Brain

Using theory and data from emotional neurobiology, I suggest a neurally realistic model of the dialogical self. The model is premised on Hermans' idea of voicing and its implications for motivation, action and subjectivity. Because states of motivated attention unify brain activity, coexisting I-positions are as problematic for neuroscience as they are for psychology. To overcome this problem, I postulate an internal monologue in which the familiar I-position is subserved by an attentional system in the orbitofrontal cortex, linked with nearby affective and premotor areas. This internal monologue is fueled by gist-like perceptual expectancies of an-other's response, and it perpetuates and adjusts itself by updating these expectancies. A second I-position may be underpinned by an attentional system in the anterior cingulate cortex and its connections. These two attentional systems are partly independent, and they compete for control based on changes in emotional content and intensity. Thus, switching activation between them may account for semi-autonomous, but not coexisting, I-positions.

Evidence for a Neo-Piagetian Stage Transition in Early Cognitive Development

Criticisms of Piaget's stage theory have led neo-Piagetians to redefine stage change as an age-related-and possibly spurt-like-shift in the level of diverse cognitive operations. This study tests a hypothesised stage shift according to this definition, using longitudinal methodology in the period of early infancy. Case's theory of development predicts a stage transition beginning at about 4 months. To test this prediction, infants' performance on a battery of six sensorimotor tasks was examined weekly as they crossed the age range between 2.5 and 5.5 months. For all tasks, a pass rate of 50% was first observed between 3.7 and 4.6 months, and task profiles showed some evidence of clustering or synchrony. In addition, onset age data indicated intra-individual synchrony in task acquisitions, suggesting discontinuous or spurt-like changes in overall development. These results are consistent with a neo-Piagetian definition of stage change, and lend support to Case's model of early cognitive development.

Inflammasome signaling affects anxiety- and depressive-like behavior and gut microbiome composition

The inflammasome is hypothesized to be a key mediator of the response to physiological and psychological stressors, and its dysregulation may be implicated in major depressive disorder. Inflammasome activation causes the maturation of caspase-1 and activation of interleukin (IL)-1β and IL-18, two proinflammatory cytokines involved in neuroimmunomodulation, neuroinflammation and neurodegeneration. In this study, C57BL/6 mice with genetic deficiency or pharmacological inhibition of caspase-1 were screened for anxiety- and depressive-like behaviors, and locomotion at baseline and after chronic stress. We found that genetic deficiency of caspase-1 decreased depressive- and anxiety-like behaviors, and conversely increased locomotor activity and skills. Caspase-1 deficiency also prevented the exacerbation of depressive-like behaviors following chronic stress. Furthermore, pharmacological caspase-1 antagonism with minocycline ameliorated stress-induced depressive-like behavior in wild-type mice. Interestingly, chronic stress or pharmacological inhibition of caspase-1 per se altered the fecal microbiome in a very similar manner. When stressed mice were treated with minocycline, the observed gut microbiota changes included increase in relative abundance of Akkermansia spp. and Blautia spp., which are compatible with beneficial effects of attenuated inflammation and rebalance of gut microbiota, respectively, and the increment in Lachnospiracea abundance was consistent with microbiota changes of caspase-1 deficiency. Our results suggest that the protective effect of caspase-1 inhibition involves the modulation of the relationship between stress and gut microbiota composition, and establishes the basis for a gut microbiota-inflammasome-brain axis, whereby the gut microbiota via inflammasome signaling modulate pathways that will alter brain function, and affect depressive- and anxiety-like behaviors. Our data also suggest that further elucidation of the gut microbiota-inflammasome-brain axis may offer novel therapeutic targets for psychiatric disorders.

Does thyroid peroxidase provide an antigenic link between thyroid autoimmunity and breast cancer?

Women with breast cancer (BC) and antithyroid peroxidase (TPO) autoantibodies (TPOAb) have a better prognosis than women lacking TPOAb. Sera from women with TPOAb displayed immunoreactivity to BC tissue by immunofluorescence that was not apparent in women without TPOAb. We hypothesize a BC/thyroid shared antigen that provides a target for humoral or cell-mediated immune activity; candidates include the sodium/iodide symporter (expressed in thyroid and BC), cross-reacting epitopes in TPO and lactoperoxidase (LPO) or TPO itself. As the association is with TPOAb, we investigated TPO expression in BC, breast peritumoral tissue (PT), other tissues (tumoral and not) and thyroid as positive control. Transcripts for known and novel TPO isoforms were detected in BC (n = 8) and PT (n = 8) but at approximately 10(4) -fold lower than in thyroid while in non-BC tumors (n = 5) they were at the limit of detection. TPO was expressed also in adipose tissue (n = 17), 10(3) -fold lower than in thyroid. Full length TPO (Mr 105-110 kDa) was detected in Western blots in the majority of examined tissues; preabsorption of the TPO antibody with recombinant TPO (but not LPO) reduced the signal, indicating specificity. The same occurred with some lower molecular weight bands, which could correspond to smaller TPO transcript isoforms, present in all samples. In conclusion, TPO is weakly expressed in BC and other tissues; this could partly explain the high frequency and protective role of TPOAb in BC patients. Further studies will investigate tissue specificity, function and immunogenicity of the novel TPO variants (some BC-specific) identified.

Developmental change in EEG theta activity in the medial prefrontal cortex during response control

Cognitive control functions continue to improve from infancy until early adulthood, allowing flexible adaptation to a complex environment. However, it remains controversial how this development in cognitive capabilities is mediated by changes in cortical activity: both age-related increases and decreases of mediofrontal neural activity have been observed and interpreted as neural underpinnings of this functional development. To better understand this developmental process, we examined EEG theta activity in the mediofrontal region using a Go/No-go response control task. We found that both pre-stimulus baseline theta-power and theta-power during the response control task, without baseline-correction, decreased with age. Conversely, when task-related theta-power was baseline corrected (using a ratio method), it exhibited a positive developmental trajectory. The age-related theta-power increase was source-localized to the anterior cingulate cortex. This increase in theta activity also partially mediated age-related improvements in response control and was greatest in a condition that demanded greater effort. Theta activity in older children also showed greater temporal reliability across trials as measured by inter-trial phase-coherence. Interestingly, directly subtracting baseline activity from task-related activity did not yield significant developmental effects, which highlights the necessity of separating and contrasting the pre-stimulus baseline with task-related processing in the understanding of neurodevelopmental changes.

Neural mechanisms of emotion regulation in childhood anxiety

BACKGROUND

The present study was designed to examine the cortical processes that mediate cognitive regulation in response to emotion-eliciting stimuli in anxious children.

METHODS

Electroencephalographic (EEG) activity was recorded from clinically anxious children (n = 29) and typically developing children (n = 34). Event-related potential components were recorded while children performed a go/no-go task using facial stimuli depicting angry, calm, and happy expressions.

RESULTS

Anxious children had significantly greater posterior P1 and frontal N2 amplitudes, components associated with attention/arousal and cognitive control, respectively, than typically developing children. Anxious children also had significantly greater error-related negativities and correct-response negativities relative to typically developing children. For the anxious group only, there were no differences in neural activation between face (emotion) types or trial (Go vs. No-go) types. A regression analysis revealed that No-go N2 amplitudes for calm faces predicted self-reported anxiety levels.

CONCLUSIONS

Anxious children appeared to show increased cortical activation regardless of the emotional content of the stimuli. Anxious children also showed greater medial-frontal activity regardless of task demands and response accuracy. Taken together, these findings suggest indiscriminate cortical processes that may underlie the hypervigilant regulatory style seen in clinically anxious individuals.

Withholding response in the face of a smile: age-related differences in prefrontal sensitivity to Nogo cues following happy and angry faces

The modulation of control processes by stimulus salience, as well as associated neural activation, changes over development. We investigated age-related differences in the influence of facial emotion on brain activation when an action had to be withheld, focusing on a developmental period characterized by rapid social-emotional and cognitive change. Groups of kindergarten and young school-aged children and a group of young adults performed a modified Go/Nogo task. Response cues were preceded by happy or angry faces. After controlling for task performance, left orbitofrontal regions discriminated trials with happy vs. angry faces in children but not in adults when a response was withheld, and this effect decreased parametrically with age group. Age-related changes in prefrontal responsiveness to facial expression were not observed when an action was required, nor did this region show age-related activation changes with the demand to withhold a response in general. Such results reveal age-related differences in prefrontal activation that are specific to stimulus valence and depend on the action required.

Transient coordinated activity within the developing brain's default network

The concept of a brain default network postulates that specific brain regions are more active when a person is engaged in introspective mental activity. Transient functional coordination between groups of neurons is thought to be necessary for information processing. Since children develop introspection as they mature, regions of the default network may establish increasing functional coordination with age, resulting in fewer fluctuations in synchronization patterns. We investigated the transient coordinated activity in regions of the default network in seventeen children aged 11 months to 17 years of age using EEG recordings while subjects were resting quietly with eyes closed. The temporal and spatial fluctuations in the phase synchrony patterns were estimated across sites associated with the default network pattern and compared to other regions. Lower variability of the spatio-temporal patterns of phase synchronization associated with the default network was observed in the older group as compared to the younger group. This indicates that functional coordination increases among regions of the default network as children develop.

Magnitude and chronometry of neural mechanisms of emotion regulation in subtypes of aggressive children

Emotion regulation is a key social skill and children who fail to master it are at risk for clinical disorders. Specific styles of emotion regulation have been associated with particular patterns of prefrontal activation. We investigated whether anxious aggressive children would reveal a different pattern of cortical activation than non-anxious aggressive children and normally-developing children. We examined the magnitude and timing of source activation underlying the N2-an ERP associated with inhibitory control-during a go/nogo task with a negative emotion induction component (loss of earned points). We estimated cortical activation for two regions of interest-a ventral prefrontal and a dorsomedial prefrontal region-for three 100-ms windows over the range of the N2 (200-500 ms). Anxious aggressive children showed high ventral prefrontal activation in the early window; non-anxious aggressive children showed high ventral prefrontal activation in the late window, but only for the duration of the emotion induction; and normally-developing children showed low ventral prefrontal activation throughout. There were no group differences in dorsomedial prefrontal activation. These results suggest that anxious aggressive children recruit ventral prefrontal activation quickly and indiscriminately, possibly giving rise to their rigid, threat-oriented approach to conflict. The late ventral prefrontal activation seen for non-anxious aggressive children may underlie a more delayed, situation-specific, but ineffective response to frustration.

Three Time Scales of Neural Self-Organization Underlying Basic and Nonbasic Emotions

Our model integrates the nativist assumption of prespecified neural structures underpinning basic emotions with the constructionist view that emotions are assembled from psychological constituents. From a dynamic systems perspective, the nervous system self-organizes in different ways at different time scales, in relation to functions served by emotions. At the evolutionary scale, brain parts and their connections are specified by selective pressures. At the scale of development, connectivity is revised through synaptic shaping. At the scale of real time, temporary networks of synchronized activity mediate responses to situations. To the degree that humans share common emotional functions, neural structuration is similar across scales, giving rise to “basic” emotions. However, unique developmental and situational factors select for neural configurations mediating emotional variants.

Dopamine and the Neural “Now”

Rather than view addiction as a disease, Heyman sees it as a choice—one that works like other choices, whereby immediate rewards outshine long-term gains. He rejects neuroscientific explanations of addictive behavior, because he believes they cast it as involuntary or disease-like. I argue that the disease-versus-choice debate creates a false dichotomy: Neuroscience does not have to frame addiction as a disease. Rather, it can help explain how addicts make impulsive choices in the moment and distort appraisal and decision-making habits in the long run. Specifically, the salience of drug-related cues is enhanced by dopamine activity in the ventral striatum, orbitofrontal cortex, and amygdala, due to the intense hedonic impact of repeated drug experiences. Moreover, dopamine-based craving peaks when drug (or alcohol or gambling) rewards become available, in the moment, and this rapid increase in attractiveness preempts rational judgment. Finally, repeated dopamine enhancement modifies brain structures to maximize the appeal of addictive activities, minimize the appeal of competing rewards, and undermine the cognitive capacities necessary to choose between them. I conclude that addiction is not a monolithic state but a recurrent series of choices that permit negotiation, and sometimes cooperation, between immediate and long-range goals.

Developmental change in the neurophysiological correlates of self-regulation in high- and low-emotion conditions

One of the most important tasks of childhood is learning to self-regulate in the presence of negative emotions. Until recently, almost no research has examined the neurophysiological correlates of emotional self-regulation as it develops over childhood and adolescence. We were interested in plotting a fine-grained developmental profile of the neural underpinnings of self-regulation, in the context of negative emotion, for 7- to 14-year-old children. We predicted that children would recruit less cortical activation with age in the service of self-regulation, reflecting increased neural efficiency with development. We also predicted that children would recruit more cortical activation with increased negative emotion, possibly reflecting greater demand on cortical resources. We administered a Go No-Go task with an emotion induction block and we measured the amplitude of the N2, an event related potential associated with inhibitory control, as it varied with block and with age. Furthermore, we estimated activation for a ventral prefrontal region of interest (ROI; suggestive of orbital frontal, ventromedial prefrontal, or rostral anterior cingulate activation) and a dorsomedial prefrontal ROI (suggestive of dorsal anterior cingulate activation) frequently modeled as cortical generators underlying the N2. Results revealed a marginal decrease in mediofrontal scalp activation, but a more pronounced decrease in activation of the ventromedial prefrontal ROI, with age. There were no age-related changes in dorsomedial prefrontal ROI activation. Lastly, as predicted, we found increased ventral prefrontal ROI activation during the negative emotion induction, possibly reflecting greater recruitment of frontocortical resources underlying emotion regulation, but developmental change in this activation was no different than for the other conditions. Thus, both self-regulation in general and emotion regulation in particular recruited less cortical activation with age, suggesting more efficient cortical mechanisms of response inhibition.

Dehydroepiandrosterone (DHEA) treatment in vitro inhibits adipogenesis in human omental but not subcutaneous adipose tissue

Dehydroepiandrosterone (DHEA), a precursor sex steroid, circulates in sulphated form (DHEAS). Serum DHEAS concentrations are inversely correlated with metabolic syndrome components and in vivo/in vitro studies suggest a role in modulating adipose mass. To investigate further, we assessed the in vitro biological effect of DHEA in white (3T3-L1) and brown (PAZ6) preadipocyte cell lines and human primary preadipocytes. DHEA (from 10(-8)M) caused concentration-dependent proliferation inhibition of 3T3-L1 and PAZ6 preadipocytes. Cell cycle analysis demonstrated unaltered apoptosis but indicated blockade at G1/S or G2/M in 3T3-L1 and PAZ6, respectively. Preadipocyte cell-line adipogenesis was not affected. In human primary subcutaneous and omental preadipocytes, DHEA significantly inhibited proliferation from 10(-8)M. DHEA 10(-7)M had opposing effects on adipogenesis in the two fat depots. Subcutaneous preadipocyte differentiation was unaffected or increased whereas omental preadipocytes showed significantly reduced adipogenesis. We conclude that DHEA exerts fat depot-specific differences which modulate body composition by limiting omental fat production.

The changing face of emotion: age-related patterns of amygdala activation to salient faces

The present study investigated age-related differences in the amygdala and other nodes of face-processing networks in response to facial expression and familiarity. fMRI data were analyzed from 31 children (3.5-8.5 years) and 14 young adults (18-33 years) who viewed pictures of familiar (mothers) and unfamiliar emotional faces. Results showed that amygdala activation for faces over a scrambled image baseline increased with age. Children, but not adults, showed greater amygdala activation to happy than angry faces; in addition, amygdala activation for angry faces increased with age. In keeping with growing evidence of a positivity bias in young children, our data suggest that children find happy faces to be more salient or meaningful than angry faces. Both children and adults showed preferential activation to mothers' over strangers' faces in a region of rostral anterior cingulate cortex associated with self-evaluation, suggesting that some nodes in frontal evaluative networks are active early in development. This study presents novel data on neural correlates of face processing in childhood and indicates that preferential amygdala activation for emotional expressions changes with age.

The time course of social-emotional processing in early childhood: ERP responses to facial affect and personal familiarity in a Go-Nogo task

To date, little is known about the neural underpinnings of social-emotional processes in young children. The present study investigated the time course of children's ERP responses to facial expression and personal familiarity, and the effect of these variables on ERP measures of effortful attention in a Go-Nogo task. Dense-array EEG was collected from 48 4-6-year-old children who were presented with pictures of their mothers' and strangers' happy and angry faces. ERPs were scored following face presentation and following a subsequent cue signaling a Go or Nogo response. Responses to face presentation showed early perceptual components that were larger following strangers' faces, suggesting facilitated rapid processing of personally important faces. A mid-latency frontocentral negativity was greatest following angry mothers' faces, indicating increased attentional monitoring and/or recognition memory evoked by an angry parent. Finally a right-lateralized late positive component was largest following angry faces, suggesting extended processing of negatively valenced social stimuli in general. Following the Go-Nogo response cue, a right-lateralized mid-latency negativity thought to measure effortful attention was larger in Nogo than Go trials, and following angry than happy faces, possibly reflecting increased effortful control required in those conditions. The present study suggests that overlapping but differentiated networks for both rapid and elaborative processing of important socio-affective information are established by 4-6 years. Moreover, the extended spatial and temporal distribution of components suggests a pattern of response to social stimuli in which more rapid processes may index personal familiarity, whereas temporally extended processes are sensitive to affective valence on both familiar and unfamiliar faces.

A Dynamic Systems Analysis of Parent–child Changes Associated with Successful “Real-world” Interventions for Aggressive Children

Studies have shown that improved parenting mediates treatment outcomes for aggressive children, but we lack fine-grained descriptions of how parent-child interactions change with treatment. The current study addresses this gap by applying new dynamic systems methods to study parent-child emotional behavior patterns. These methods tap moment-to-moment changes in interaction processes within and across sessions and quantify previously unmeasured processes of change related to treatment success. Aggressive children and their parents were recruited from combined Parent Management Training and Cognitive-behavioral programs in "real world" clinical settings. Behavioral outcomes were assessed by reports from parents and clinicians. At pre- and post-treatment, home visits were videotaped while parents and children discussed consecutively: a positive topic, a mutually unresolved problem, and another positive topic. Results showed that significant improvements in children's externalizing behavior were associated with increases in parent-child emotional flexibility during the problem-solving discussion. Also, dyads who improved still expressed negative emotions, but they acquired the skills to repair conflicts, shifting out of their negative interactions to mutually positive patterns.

Behavioral differences in aggressive children linked with neural mechanisms of emotion regulation

Children with aggressive behavior problems may have difficulties regulating negative emotions, resulting in harmful patterns of interpersonal behavior at home and in the schoolyard. Ventral and dorsal regions of the prefrontal cortex (PFC) have been associated with response inhibition and self-control-key components of emotion regulation. Our research program aims to explore differences among aggressive and normal children in the activation of these cortical regions during emotional episodes, to the extent possible using electrophysiological techniques, to identify diagnostic subtypes, gain insights into their interpersonal difficulties, and help develop effective treatment strategies. This report reviews several recent studies investigating individual and developmental differences in cortical mechanisms of emotion regulation, corresponding with different patterns of interpersonal behavior. Our methods include event-related potentials (ERPs) and cortical source modeling, using dense-array electroencephalography (EEG) technology, as well as videotaped observations of parent-child interactions, with both normal and aggressive children. By relating patterns of brain activation to observed behavioral differences, we find (i) a steady decrease in cortical activation subserving self-regulation across childhood and adolescence, (ii) different cortical activation patterns as well as behavioral constellations distinguishing subtypes of aggressive children, and (iii) robust correlations between the activation of cortical mediators of emotion regulation and flexibility in parent-child emotional communication in children referred for aggressive behavior problems. These findings point toward models of developmental psychopathology based on the interplay among biological, psychological, and social factors.

Neurophysiological mechanisms of emotion regulation for subtypes of externalizing children

Children referred for externalizing behavior problems may not represent a homogeneous population. Our objective was to assess neural mechanisms of emotion regulation that might distinguish subtypes of externalizing children from each other and from their normal age mates. Children with pure externalizing (EXT) problems were compared with children comorbid for externalizing and internalizing (MIXED) problems and with age-matched controls. Only boys were included in the analysis because so few girls were referred for treatment. We used a go/no-go task with a negative emotion induction, and we examined dense-array EEG data together with behavioral measures of performance. We investigated two event-related potential (ERP) components tapping inhibitory control or self-monitoring - the inhibitory N2 and error-related negativity (ERN) - and we constructed source models estimating their cortical generators. The MIXED children's N2s increased in response to the emotion induction, resulting in greater amplitudes than EXT children in the following trial block. ERN amplitudes were greatest for control children and smallest for EXT children with MIXED children in between, but only prior to the emotion induction. These results were paralleled by behavioral differences in response time and performance monitoring. ERP activity was localized to cortical sources suggestive of the dorsal anterior cingulate for control children, posterior cingulate areas for the EXT children, and both posterior cingulate and ventral cingulate/prefrontal regions for the MIXED children. These findings highlight different mechanisms of self-regulation underlying externalizing subtypes and point toward distinct developmental pathways and treatment strategies.

Event-related potential measures of emotion regulation in early childhood

Emotion regulation in adults may be mediated by frontal cortical activities that adjust attention in response to challenging emotions. We examined event-related potentials across emotional conditions to assess normative patterns and individual differences in cortical mechanisms of emotion regulation in 4-6-year-olds. The children viewed pictures of angry, neutral, and happy faces during a Go/No-go task. Angry faces generated the greatest (frontocentral) N2 amplitudes and fastest N2 latencies, and happy faces produced the smallest amplitudes and slowest latencies. Frontal electrodes showed larger N2s to angry faces in the Go condition. The P3b was also largest for angry faces. More fearful children showed faster latency N2s to angry faces. These results are interpreted in terms of early-developing mechanisms for regulating anxiety and processing emotional information.

Neurophysiological correlates of emotion regulation in children and adolescents

Psychologists consider emotion regulation a critical developmental acquisition. Yet, there has been very little research on the neural underpinnings of emotion regulation across childhood and adolescence. We selected two ERP components associated with inhibitory control-the frontal N2 and frontal P3. We recorded these components before, during, and after a negative emotion induction, and compared their amplitude, latency, and source localization over age. Fifty-eight children 5-16 years of age engaged in a simple go/no-go procedure in which points for successful performance earned a valued prize. The temporary loss of all points triggered negative emotions, as confirmed by self-report scales. Both the frontal N2 and frontal P3 decreased in amplitude and latency with age, consistent with the hypothesis of increasing cortical efficiency. Amplitudes were also greater following the emotion induction, only for adolescents for the N2 but across the age span for the frontal P3, suggesting different but overlapping profiles of emotion-related control mechanisms. No-go N2 amplitudes were greater than go N2 amplitudes following the emotion induction at all ages, suggesting a consistent effect of negative emotion on mechanisms of response inhibition. No-go P3 amplitudes were also greater than go P3 amplitudes and they decreased with age, whereas go P3 amplitudes remained low. Finally, source modeling indicated a developmental decline in central-posterior midline activity paralleled by increasing activity in frontal midline regions suggestive of the anterior cingulate cortex. Negative emotion induction corresponded with an additional right ventral prefrontal or temporal generator beginning in middle childhood.

Who put the self in self-organization? A clarification of terms and concepts for developmental psychopathology

The term self-organization has at least two meanings for developmental psychopathologists: the spontaneous emergence of order in developing systems and the consolidation of that part of the person called the self. The first meaning is shared across the sciences at large, and it denotes a general model of change and growth in complex systems. We review principles of self-organization from the natural sciences and discuss their application to the study of human development. We then suggest possible sources and consequences of terminological confusion in developmental psychology and offer some potential resolutions. The "self" in self-organization seems a special case of this confusion, and it can be addressed by modeling the self as both autonomous agent and emergent form. We outline preliminary directions for this modeling and then go on to a more general discussion of how principles of self-organization can help bring developmental psychopathology closer to its goals.

Neurophysiological Correlates of Emotion Regulation in Children and Adolescents

Psychologists consider emotion regulation a critical developmental acquisition. Yet, there has been very little research on the neural underpinnings of emotion regulation across childhood and adolescence. We selected two ERP components associated with inhibitory control—the frontal N2 and frontal P3. We recorded these components before, during, and after a negative emotion induction, and compared their amplitude, latency, and source localization over age. Fifty-eight children 5–16 years of age engaged in a simple go/no-go procedure in which points for successful performance earned a valued prize. The temporary loss of all points triggered negative emotions, as confirmed by self-report scales. Both the frontal N2 and frontal P3 decreased in amplitude and latency with age, consistent with the hypothesis of increasing cortical efficiency. Amplitudes were also greater following the emotion induction, only for adolescents for the N2 but across the age span for the frontal P3, suggesting different but overlapping profiles of emotion-related control mechanisms. No-go N2 amplitudes were greater than go N2 amplitudes following the emotion induction at all ages, suggesting a consistent effect of negative emotion on mechanisms of response inhibition. No-go P3 amplitudes were also greater than go P3 amplitudes and they decreased with age, whereas go P3 amplitudes remained low. Finally, source modeling indicated a developmental decline in central-posterior midline activity paralleled by increasing activity in frontal midline regions suggestive of the anterior cingulate cortex. Negative emotion induction corresponded with an additional right ventral prefrontal or temporal generator beginning in middle childhood.

A state space analysis of emotion and flexibility in parent-child interactions

Negative emotion has been shown to reduce flexibility in cognition and behavior. We examined interpersonal flexibility during negative emotional episodes within parent-child interactions. Fifty-five mothers and early-adolescent daughters were observed during a positive discussion, a negative (conflict) discussion, and another positive discussion. Codes of moment-to-moment changes in emotion expression were used to create state space grids from which measures of emotional valence and flexibility were derived. As expected, mean flexibility was lowest during the conflict discussion when negative emotion peaked, suggesting that interpersonal flexibility decreases with increasing negative emotion. Sub-groups identified as low or high in stress were also compared. Dyads with girls reporting more stressful events showed lower flexibility during the first positive discussion. However, dyads expressing more negative emotion during the conflict discussion were also more flexible, suggesting that flexible dyadic styles permit more negative emotion. These individual difference findings are discussed in terms of the suppression versus expression of negative emotions.

Neural correlates of cognitive control in childhood and adolescence: Disentangling the contributions of age and executive function

Dense-array (128-channel) electroencephalography (EEG) was used to record event-related potentials (ERPs) from 33 participants between 7 and 16 years of age while they performed a Go/Nogo task. The frontal (Nogo) N2 component of the ERP was taken as an index of cognitive control, and examined in relation to both age and independent assessments of executive function (EF), including the Iowa Gambling Task (IGT), the Stroop task, a delay discounting task, and backward digit span. Better performance on the IGT and the Stroop task was associated with smaller N2 amplitudes, over and above effects of age. N2 latencies decreased with age but were not predicted by EF. Source modeling of the N2 revealed neural generators in areas suggestive of cingulate cortex and orbitofrontal cortex, and the locations of these generators varied systematically with EF (IGT and Stroop task): the cingulate generator was more anterior for good EF participants at all ages; the orbitofrontal generator was relatively left lateralized for younger and for poorer EF participants. Taken together, these findings suggest that age-related decreases in N2 amplitude, but not N2 latency, reflect the development of cognitive control and cannot be attributed solely to incidental changes that may affect assessments of the N2 (e.g., increases in skull thickness). Functionally relevant decreases in N2 amplitude may reflect changes in the regions of cortex giving rise to the N2.

Bridging emotion theory and neurobiology through dynamic systems modeling

Efforts to bridge emotion theory with neurobiology can be facilitated by dynamic systems (DS) modeling. DS principles stipulate higher-order wholes emerging from lower-order constituents through bidirectional causal processes--offering a common language for psychological and neurobiological models. After identifying some limitations of mainstream emotion theory, I apply DS principles to emotion-cognition relations. I then present a psychological model based on this reconceptualization, identifying trigger, self-amplification, and self-stabilization phases of emotion-appraisal states, leading to consolidating traits. The article goes on to describe neural structures and functions involved in appraisal and emotion, as well as DS mechanisms of integration by which they interact. These mechanisms include nested feedback interactions, global effects of neuromodulation, vertical integration, action-monitoring, and synaptic plasticity, and they are modeled in terms of both functional integration and temporal synchronization. I end by elaborating the psychological model of emotion-appraisal states with reference to neural processes.

Trouble ahead: predicting antisocial trajectories with dynamic systems concepts and methods

This paper reviews and evaluates a set of studies that utilize dynamic systems (DS) principles, and in two cases dynamic systems methods, for predicting antisocial development and other behavioral outcomes. I suggest that the emphasis of DS approaches on process and nonlinear causation is very different from the emphasis in developmental psychopathology on prediction, yet the marriage of these approaches is necessary to capture the complex interactions that give rise to problematic trajectories. The studies reviewed do indeed uncover predictive relations that would have been difficult to conceptualize or impossible to find using more traditional strategies. In discussing these studies. I suggest DS interpretations of emerging individual differences, phase-specific change, sleeper effects, mediating variables, and behavioral rigidity versus malleability, in the context of developmental prediction. I also discuss the advantages of moving from DS concepts to DS methods in clinical-developmental research.

Biological activity of activating thyrotrophin receptor mutants: modulation by iodide

Epidemiological studies have revealed a significantly higher incidence of toxic adenoma (TA) and toxic multi-nodular goitre (TMNG) in regions of iodine deficiency. Fifty to eighty percent of TA and TMNG are caused by activation of the cAMP pathway, mostly by mutations in the thyrotrophin receptor (TSHR). We aimed to investigate whether iodide could modulate the biological effects of activating TSHR mutations. We have applied an in vitro model of TA comprising FRTL-5 cells stably expressing activating TSHR. We have mimicked the in vivo situation by examining the effects of prolonged exposure to iodide on the proliferation and signal transduction etc. of these cells. We observed an iodide-induced 'inhibition of proliferation' which was significant from 10 mM in the presence of serum but from 1 mM in its absence. The inhibition of proliferation was significantly higher in the activating mutant expressing FRTL-5 compared with control Neo or wild-type TSHR, indicating that the effect was mediated via the cAMP cascade. The effect was neither due to hyper-tonicity nor was it the result of an increase in cell death either by apoptosis or necrosis. Prolonged exposure to iodide produces an increase in cells in the G2 and post-G2 phases, indicating that G2/M blockade contributes to the mechanism of inhibition. The mutant expressing FRTL-5 cells have increased proliferation when chronically exposed to TSH, and this is associated with a reduction in phosphorylated (p) CREB levels. This contrasts with the effect of iodide in which inhibition of proliferation is accompanied by an increase in pCREB. In conclusion, our studies indicate that the biological effects of activating TSHR mutations vary with the ambient iodide supply and could be masked in regions of high iodine intake.

Reorganization in coping behavior at 1 1/2 years: dynamic systems and normative change

By the age of 1 year toddlers demonstrate distinct coping habits for dealing with frustration. However, these habits may be open to change and reorganization at subsequent developmental junctures. We investigated change in coping habits at 18-20 months, a normative age for major advances in social cognition, focusing on the dynamic systems principles of fluctuation and novelty at transitions. Specifically, we asked whether month-to-month fluctuation, novel behavioral habits and real-time variability increased at the age of a normative transition, despite individual differences in the content of behavior. Infants were given frustrating toys while their mothers sat nearby without helping, on monthly visits at 14-25 months (before, during and after the hypothesized transition). State space grids representing patterns of behavioral durations were constructed for each episode and compared over age. As predicted, month-to-month fluctuation in grid patterns increased temporarily between 17 and 20 months, partly independently of a concurrent peak in distress, and new behavioral habits replaced old ones at the same age. Coping habits changed differently for high-and low-distressed toddlers. However, changes in real-time variability did not generally meet our expectations.

The role of the orbitofrontal cortex in normally developing compulsive-like behaviors and obsessive-compulsive disorder

Mounting evidence concerning obsessive-compulsive disorders points to abnormal functioning of the orbitofrontal cortices. First, patients with obsessive-compulsive disorder (OCD) perform poorly on tasks that rely on response suppression/motor inhibition functions mediated by the orbitofrontal cortex relative to both normal and clinical controls. Second, patients with OCD exhibit functional hyperactivity in lateral orbitofrontal and related structures corresponding with symptom severity. In this article, we compare these neurocognitive correlates of OCD with the executive and neural underpinnings of "compulsive-like" behaviors that are common in normal childhood. We discuss the phenomenology and natural history of normative compulsive-like behaviors as well as the behavioral, emotional, and cognitive continuities between typical and pathological obsessive-compulsive behaviors. We then examine associations between children's executive performance deficits and their observed compulsive-like characteristics. We relate these patterns to executive deficits shown by adults with OCD. Finally, we speculate on the developmental neurobiology of children's compulsive-like behaviors, with particular attention to orbitofrontal functions including behavioral and emotional regulation, and we suggest similarities and differences with the neurobiology of OCD. In making these comparisons, we hope to open a dialogue between researchers who study underlying brain pathologies associated with OCD and those who explore the neurocognitive bases of normal development.

Emotion regulation in the brain: conceptual issues and directions for developmental research

Emotion regulation cannot be temporally distinguished from emotion in the brain, but activation patterns in prefrontal cortex appear to mediate cognitive control during emotion episodes. Frontal event-related potentials (ERPs) can tap cognitive control hypothetically mediated by the anterior cingulate cortex, and developmentalists have used these to differentiate age, individual, and emotion-valence factors. Extending this approach, the present article outlines a research strategy for studying emotion regulation in children by combining emotion induction with a go/no-go task known to produce frontal ERPs. Preliminary results indicate that medial-frontal ERP amplitudes diminish with age but become more sensitive to anxiety, and internalizing children show higher amplitudes than noninternalizing children, especially when anxious. These results may reflect age and individual differences in the effortful regulation of negative emotion.

Biological activity of activating thyroid-stimulating hormone receptor mutants depends on the cellular context

Activating TSH receptor (TSHR) mutations are a major cause of toxic thyroid adenoma and familial hyperthyroidism, and more than 37 such mutations have been described. Previously their functional activity had been assessed in terms of cAMP and inositol phosphate production and predominantly in transiently transfected COS-7 (monkey embryonic kidney cells), a model that does not reflect effects on thyrocyte proliferation and function. Here we have performed a systematic comparison of wild-type and seven gain-of-function TSHR mutants, introduced into rat FRTL-5 and human thyrocytes, using retroviral vectors. Our results show that 1) biological potency of TSHR mutants in thyroid cells does not correlate with their cAMP levels in transfected COS cells, highlighting the importance of cellular context and level of expression when assessing biological effects of oncogenic mutations; 2) dissociation between stimulation of function and growth occurs with thyrocyte differentiated functions more readily stimulated than growth; 3) TSHR mutants show a similar order of potency in FRTL-5 cells and human thyrocytes; 4) mutants inducing the highest stimulation of adenylyl cyclase may paradoxically fail to induce proliferation; and 5) biological effects of cAMP activating TSHR mutants are attenuated by complex counterregulatory mechanisms at least at the level of phosphodiesterases and cAMP regulatory element modulator isoforms.

Antitumor activity of ER-51785, a new peptidomimetic inhibitor of farnesyl transferase: synergistic effect in combination with paclitaxel

Inhibitors of ras farnesylation have been extensively studied in the preclinical stage, and some of them are being developed in the clinic. Herein, we describe the antitumor activity of a new farnesyl transferase inhibitor, ER-51785. In vitro, ER-51785 selectively inhibited farnesyl transferase activity (IC50 = 77 nM) compared with geranylgeranyl transferase I activity (IC50 = 4200 nM). In cells, ER-51785 inhibited posttranslational processing of H-ras with IC50 = 28 nM, but not that of rap 1A at concentrations up to 50 microM. This compound also strongly inhibited colony formation of H-ras-transformed NIH 3T3 fibroblasts and EJ-1 bladder carcinoma cells. In vivo, ER-51785 showed potent tumor regression activity against EJ-1 xenografts but only modest activity against MIA PaCa-2 xenografts. Treatment of ER-51785 in combination with paclitaxel exhibited synergistic effects against colony formation and tumor growth of MIA PaCa-2 cells. The results presented herein support the idea that farnesyl transferase inhibitors alone and in combination with other chemotherapeutic agents have the potential to be developed as therapies for tumors expressing H-ras or K-ras oncogenes.

Adenosine-regulated cell proliferation in pituitary folliculostellate and endocrine cells: differential roles for the A(1) and A(2B) adenosine receptors

A(1) and A(2) adenosine receptors have been identified in the pituitary gland, but the cell type(s) on which they are located and their effects on pituitary cell growth are not known. Therefore, we analyzed the expression of A(1) and A(2) receptors in primary rat anterior pituitary cells, two pituitary folliculostellate (TtT/GF and Tpit/F1) and two pituitary endocrine (GH(3) and AtT20) cell lines, and compared their effects on cell proliferation. In anterior pituitary and folliculostellate cells, adenosine and adenosine receptor agonists (5'-N-ethylcarboxamidoadenosine, a universal agonist, and CGS 21680, an A(2A) receptor agonist) stimulated cAMP levels with a rank order of potency that indicates the presence of functional A(2B) receptors. This stimulation, however, was not observed in either GH(3) or AtT20 cells, where adenosine and the A(1) receptor agonist 2-chloro-N(6)-cyclopentyladenosine inhibited VIP/forskolin-stimulated cAMP production. Expression of A(2B) and A(1) receptors in the folliculostellate cells and that of the A(1) receptor in the endocrine cells were confirmed by RT-PCR, immunocytochemistry, and ligand binding. Adenosine and 5'-N-ethylcarboxamidoadenosine dose-dependently (10 nM to 10 microM) stimulated growth in the folliculostellate, but not in the endocrine, cells, whereas in the latter, 100 microM adenosine and 2-chloro-N(6)-cyclopentyladenosine inhibited cell proliferation by slowing cell cycle progression. These data highlight the differential expression of A(1) and A(2B) adenosine receptors in pituitary cells and provide evidence for opposing effects of adenosine on pituitary folliculostellate and endocrine cell growth.

Mitogen-activated protein kinase mediates epidermal growth factor-induced morphogenesis in pituitary GH3 cells

Epidermal growth factor (EGF) causes pituitary GH3 cells to change from their normal predominantly rounded morphology to much more elongated cells with extensive filopodia, and this effect is accompanied by a parallel increase in cell volume. In view of this, and because EGF receptor expression is increased in some pituitary tumours, we examined the mechanism of this EGF-induced morphological effect as it may play a role in tumour invasiveness. The effect of treatment of the cells with EGF (1 nm, 4 days) was determined visually (expressed as percent non round cells) and by measuring the cell volume by Coulter Counter analysis. EGF treatment caused the cells to change their morphology with percent non round cells increasing from 37% in control cells to 74% in EGF-treated cultures; this was accompanied by a parallel increase in cell volume. Treatment of the cells with EGF in the presence of the MEK1 inhibitor (PD98059) completely blocked the EGF-induced morphological changes, showing that activation of the mitogen-activated protein kinase (MAPK) pathway is necessary to mediate this effect. Transfection of the cells with a constitutively activated mutant of MEK1 produced a similar morphological change to that produced by EGF treatment, with the proportion of non round cells increasing to 62% with a parallel increase in cell volume compared to cells transfected with the empty vector, demonstrating that direct activation of MAPK pathway is sufficient to mediate the observed morphological effects. The effects produced by activated MEK1 transfection could be blocked by PD98059. EGF had opposing effects on prolactin and growth hormone (GH) secretion by the cells, increasing prolactin release and inhibiting GH release. Transfection of the cells with activated MEK1 produced similar effects on hormone release as EGF treatment. In conclusion, the morphological effects of EGF on GH3 cells are mediated by activation of the MAPK pathway as blockade of this pathway abolished the observed effect, and direct activation of this pathway by transfection with an activated mutant of MEK1 was able to duplicate these effects. This mechanism may contribute to the growth and possibly local invasiveness of some pituitary tumours that express the EGF receptor.

Loss of ACTH expression in cultured human corticotroph macroadenoma cells is consistent with loss of the POMC gene signal sequence

The proopiomelanocortin (POMC) gene is highly expressed in the pituitary gland where the resulting mRNA of 1200 base pairs (bp) gives rise to a full-length protein sequence. In peripheral tissues however both shorter and longer POMC variants have been described, these include for example placental tissue which contain 800 (truncated at the 5' end) and 1500 as well as the 1200 bp transcripts. The importance of the 800 bp transcript is unclear as the lack of a signal sequence renders the molecule to be non-functional. This transcript has not been previously demonstrated in the pituitary gland. In this report we show evidence of a 5' truncated POMC gene in human pituitary corticotroph macroadenoma cells (JE) maintained in primary culture for >1 year. The original tumour tissue and the derived cells during early passage (up to passage 4-5) immunostained for ACTH and in situ hybridisation confirmed the presence of the POMC gene in the cultured cells. These cells also secreted 15-40 pg/10(5) cells/24 h ACTH. In addition, as expected RT-PCR demonstrated the presence of all three POMC gene exons and is thus indicative of a full-length POMC gene. In late culture passages (passages 8-15) JE cells ceased to express ACTH and cell growth became very slow due presumably to cells reaching their Hayflick limit. ACTH immunostaining in these cells was undetectable and ACTH secretion was also at the detection limits of the assay and no greater than 10 pg/10(5) cells/24 h. ACTH precursor molecules were also undetectable. RT-PCR for the POMC gene in these late passage cells showed that only exon 3 was detectable, in contrast to early passage cells where all three exons were present. In summary we isolated in culture, human pituitary cells that possessed initially all three exons of the POMC gene and immunostained for ACTH. On further passaging these cells showed a loss of exons 1 and 2 in the POMC gene and a loss of ACTH immunostaining and secretion. We would like to suggest that the loss of ACTH peptide expression in these late passage cells is in part due to the loss of the POMC signal sequence. An alternative explanation for our findings is that there were originally two populations of corticotrophs in the cultures, one of which possessed the full-length POMC gene and the other only the 5' truncated POMC transcript and it is these latter cells which survived in culture. In either scenario this is the first report of the 5' truncated POMC gene occurring in pituitary cells.

Synthesis and evaluation of some hydroxyproline-derived peptidomimetics as isoprenyltransferase inhibitors

CA1A2X peptidomimetics containing a modified proline at position A2 were prepared and evaluated for their ability to inhibit farnesyltransferase (FTase) and geranylgeranyltransferase I (GGTase I) in enzymatic and cell-based assays. These compounds inhibited farnesylation of H-ras in vitro in the high nanomolar to low micromolar IC50 range.

The promise of dynamic systems approaches for an integrated account of human development

After decades of theoretical fragmentation and insularity, a converging explanatory framework based on general scientific principles is an important goal for developmental psychology. Dynamic systems approaches may provide such a framework, using principles of self-organization to explain how novel forms emerge without predetermination and become increasingly complex with development. New trends in traditional theoretical families emphasize systemic, emergent processes, and these can now be explicated with principles of self-organization that apply to all natural systems. Self-organization thus provides a single explanation for the multiple facets of development, integrating diverse developmental viewpoints within a larger scientific perspective.

Synthesis and evaluation of hydroxyproline-derived isoprenyltransferase inhibitors

A series of peptidomimetics based on a hydroxyproline scaffold was prepared and evaluated for inhibition of farnesyltransferase and geranylgeranyltransferase I in both enzymatic and cell-based assays. A number of analogs were potent and selective inhibitors of FTase, while one compound (22) was nonselective in the enzymatic assays but eight-fold selective for inhibition of GGTase in the cellular assay (IC50 = 0.39 microM).