[Teaching during the COVID-19 pandemic: how do medical students evaluate interactive video-based distance bedside teaching in otorhinolaryngology?] / Ausbildung in COVID-19-Pandemie-Zeiten: Wie bewerten Medizinstudierende einen interaktiven, videobasierten Distanzunterricht am Patienten im Fach Hals-Nasen-Ohren-Heilkunde?

BACKGROUND: The first wave of the SARS-CoV­2 pandemic required substantial changes in the teaching of medical students, with strict avoidance of direct contact between students and patients. Therefore, the teaching format "bedside teaching" was implemented and conducted as an interactive video-based distance bedside teaching. OBJECTIVE: The objective of this study was to analyze a students' evaluation of this teaching concept in otorhinolaryngology. MATERIALS AND METHODS: From an ENT examination room, the situation was transmitted live to the students in a lecture hall, who could interact with the patients through a video connection. Macro-, micro-, and endoscopic images were transmitted into the lecture hall in real time. Evaluation was performed by means of an online questionnaire with 13 questions (Likert scale) as well as by free-text feedback. RESULTS: The response rate was 16.8% (42 of 250 students). Overall, 85.7% had a positive impression, and it was generally considered that the concept was well implemented in light of the special situation. However, students would rather not renounce direct patient contact, even if a certain compensation by video transmission was reported. Overall, this teaching concept was considered as educative, and students could imagine using such a teaching concept more often in the future. CONCLUSION: This teaching model cannot replace classical bedside teaching, but represents a good alternative-particularly in otorhinolaryngology-if classical bedside teaching is not possible due to the pandemic situation. Aspects of the interactive video-based distance bedside teaching could be implemented into classical teaching concepts in the future.

Adverse childhood experiences and substance misuse in young people in India: results from the multisite cVEDA cohort.

BACKGROUND: Adverse childhood experiences (ACEs) increases vulnerability to externalising disorders such as substance misuse. The study aims to determine the prevalence of ACEs and its association with substance misuse. METHODS: Data from the Consortium on Vulnerability to Externalising Disorders and Addictions (cVEDA) in India was used (n = 9010). ACEs were evaluated using the World Health Organisation (WHO) Adverse Childhood Experiences International Questionnaire whilst substance misuse was assessed using the WHO Alcohol, Smoking and Substance Involvement Screening Test. A random-effects, two-stage individual patient data meta-analysis explained the associations between ACEs and substance misuse with adjustments for confounders such as sex and family structure. RESULTS: 1 in 2 participants reported child maltreatment ACEs and family level ACEs. Except for sexual abuse, males report more of every individual childhood adversity and are more likely to report misusing substances compared with females (87.3% vs. 12.7%). In adolescents, family level ACEs (adj OR 4.2, 95% CI 1.5-11.7) and collective level ACEs (adj OR 6.6, 95% CI 1.4-31.1) show associations with substance misuse whilst in young adults, child level ACEs such as maltreatment show similar strong associations (adj OR 2.0, 95% CI 1.1-3.5). CONCLUSION: ACEs such as abuse and domestic violence are strongly associated with substance misuse, most commonly tobacco, in adolescent and young adult males in India. The results suggest enhancing current ACE resilience programmes and 'trauma-informed' approaches to tackling longer-term impact of ACEs in India. FUNDING: Newton Bhabha Grant jointly funded by the Medical Research Council, UK (MR/N000390/1) and the Indian Council of Medical Research (ICMR/MRC-UK/3/M/2015-NCD-I).

[IMAGEN and beyond: novel population neuroscientific strategies for clinical and global cohorts in the STRATIFY and GIGA consortia]. / Jenseits von IMAGEN: populationsneurowissenschaftliche Strategien für klinische und globale Kohorten in den STRATIFY- und GIGA-Konsortien.

Cohort studies provide the possibility to more precisely define treatment and preventive approaches to mental diseases, when genetic and personal influences as well as sociocultural and environmental factors and their interactions are taken into account. This article presents cohort research approaches, which are dedicated to this aim and reports the lessons learnt and achievements made in the IMAGEN cohort study and the resulting further developments. Specifically, we focus on novel assessment instruments, the implementation of larger clinical and geographic ranges and innovative forms of data analysis.

[The IMAGEN cohort: perspectives and problems of longitudinal research]. / Die IMAGEN-Kohorte: Perspektiven und Probleme longitudinaler Forschung.

BACKGROUND: Genetic risk factors for major mental disorders identified in psychiatric research show a substantial overlap. Therefore, it has been suggested that neurobiological research should focus on intermediate phenotypes that reflect shared aspects of different mental disorders due to overlapping genetic effects and environmental factors. Longitudinal studies are required to assess the interaction between genetic variability and modifying environmental factors and to investigate the effects on intermediate phenotypes and (mediated by them) on the expression of individual mental disorders. OBJECTIVE: Discussion of the possibilities and limitations of longitudinal cohort studies using the IMAGEN study as an example. MATERIAL AND METHODS: The results of the European IMAGEN study are presented with a focus on addiction. RESULTS: The longitudinal assessments of the IMAGEN cohort revealed that neuroimaging data indicating a low activation of the dopaminergic reinforcement system detected at the age of 14 years are predictive for increased drug use. In addition to genetic factors, environmental influences such as maternal smoking during pregnancy were correlated with this low activation. CONCLUSION: Longitudinal neurobiological basic research can validate the effects of candidate genes and reveal relevant environmental factors. Relevant modifiable factors indicated by the IMAGEN study and related datasets include drug use during pregnancy, trauma and other experiences of violence, social disadvantage and exclusion.

[Potentials and limits of aging cohort studies for geriatric psychiatry]. / Potenziale und Grenzen von Alternskohortenstudien für die Gerontopsychiatrie.

The sizeable number of population-based cohort studies of aging in Germany have provided highly valuable contributions for the specification of risk factors and predictors for frequent mental disorders in old age, especially dementia and depression. The results from these cohort studies enable the specification of mechanisms for the development of and preventative interventions for common mental disorders in old age. On the other hand, there is a significant paucity of clinical cohort studies investigating disease trajectories and possible markers for specific individualized interventions of frequent mental disorders in old age. In this article, we report selected key findings from cohort studies of aging and discuss novel approaches for the integration and harmonization of population-based and clinical cohort studies.

An integrated brain-behavior model for working memory.

Working memory (WM) is a central construct in cognitive neuroscience because it comprises mechanisms of active information maintenance and cognitive control that underpin most complex cognitive behavior. Individual variation in WM has been associated with multiple behavioral and health features including demographic characteristics, cognitive and physical traits and lifestyle choices. In this context, we used sparse canonical correlation analyses (sCCAs) to determine the covariation between brain imaging metrics of WM-network activation and connectivity and nonimaging measures relating to sensorimotor processing, affective and nonaffective cognition, mental health and personality, physical health and lifestyle choices derived from 823 healthy participants derived from the Human Connectome Project. We conducted sCCAs at two levels: a global level, testing the overall association between the entire imaging and behavioral-health data sets; and a modular level, testing associations between subsets of the two data sets. The behavioral-health and neuroimaging data sets showed significant interdependency. Variables with positive correlation to the neuroimaging variate represented higher physical endurance and fluid intelligence as well as better function in multiple higher-order cognitive domains. Negatively correlated variables represented indicators of suboptimal cardiovascular and metabolic control and lifestyle choices such as alcohol and nicotine use. These results underscore the importance of accounting for behavioral-health factors in neuroimaging studies of WM and provide a neuroscience-informed framework for personalized and public health interventions to promote and maintain the integrity of the WM network.

Ventral striatal regulation of CREM mediates impulsive action and drug addiction vulnerability.

Impulsivity, a multifaceted behavioral hallmark of attention-deficit/hyperactivity disorder (ADHD), strongly influences addiction vulnerability and other psychiatric disorders that incur enormous medical and societal burdens yet the neurobiological underpinnings linking impulsivity to disease remain poorly understood. Here we report the critical role of ventral striatal cAMP-response element modulator (CREM) in mediating impulsivity relevant to drug abuse vulnerability. Using an ADHD rat model, we demonstrate that impulsive animals are neurochemically and behaviorally more sensitive to heroin and exhibit reduced Crem expression in the nucleus accumbens core. Virally increasing Crem levels decreased impulsive action, thus establishing a causal relationship. Genetic studies in seven independent human populations illustrate that a CREM promoter variant at rs12765063 is associated with impulsivity, hyperactivity and addiction-related phenotypes. We also reveal a role of Crem in regulating striatal structural plasticity. Together, these results highlight that ventral striatal CREM mediates impulsivity related to substance abuse and suggest that CREM and its regulated network may be promising therapeutic targets.

A new locus regulating MICALL2 expression was identified for association with executive inhibition in children with attention deficit hyperactivity disorder.

Impaired executive inhibition is a core deficit of attention deficit hyperactivity disorder (ADHD), which is a common childhood-onset psychiatric disorder with high heritability. In this study, we performed a two-stage genome-wide association study of executive inhibition in ADHD in Han Chinese. We used the Stroop color-word interference test to evaluate executive inhibition. After quality control, 780 samples with phenotype and covariate data were included in the discovery stage, whereas 922 samples were included in the replication stage. We identified one new significant locus at 7p22.3 for the Stroop word interference time (rs11514810, P=3.42E-09 for discovery, P=0.01176 for replication and combined P=5.249E-09). Regulatory feature analysis and expression quantitative trait loci (eQTL) data showed that this locus contributes to MICALL2 expression in the human brain. Most genes in the network interacting with MICALL2 were associated with psychiatric disorders. Furthermore, hyperactive-impulsive-like behavior was induced by reducing the expression of the zebrafish gene that is homologous to MICALL2, which could be rescued by tomoxetine (atomoxetine), a clinical medication for ADHD. Our results suggested that MICALL2 is a new susceptibility gene for executive inhibition deficiency related to hyperactive-impulsive behavior in ADHD, further emphasizing the possible role of neurodevelopmental genes in the pathogenic mechanism of ADHD.

The Arf6 activator Efa6/PSD3 confers regional specificity and modulates ethanol consumption in Drosophila and humans.

Ubiquitously expressed genes have been implicated in a variety of specific behaviors, including responses to ethanol. However, the mechanisms that confer this behavioral specificity have remained elusive. Previously, we showed that the ubiquitously expressed small GTPase Arf6 is required for normal ethanol-induced sedation in adult Drosophila. Here, we show that this behavioral response also requires Efa6, one of (at least) three Drosophila Arf6 guanine exchange factors. Ethanol-naive Arf6 and Efa6 mutants were sensitive to ethanol-induced sedation and lacked rapid tolerance upon re-exposure to ethanol, when compared with wild-type flies. In contrast to wild-type flies, both Arf6 and Efa6 mutants preferred alcohol-containing food without prior ethanol experience. An analysis of the human ortholog of Arf6 and orthologs of Efa6 (PSD1-4) revealed that the minor G allele of single nucleotide polymorphism (SNP) rs13265422 in PSD3, as well as a haplotype containing rs13265422, was associated with an increased frequency of drinking and binge drinking episodes in adolescents. The same haplotype was also associated with increased alcohol dependence in an independent European cohort. Unlike the ubiquitously expressed human Arf6 GTPase, PSD3 localization is restricted to the brain, particularly the prefrontal cortex (PFC). Functional magnetic resonance imaging revealed that the same PSD3 haplotype was also associated with a differential functional magnetic resonance imaging signal in the PFC during a Go/No-Go task, which engages PFC-mediated executive control. Our translational analysis, therefore, suggests that PSD3 confers regional specificity to ubiquitous Arf6 in the PFC to modulate human alcohol-drinking behaviors.

EFhd2/Swiprosin-1 is a common genetic determinator for sensation-seeking/low anxiety and alcohol addiction.

In many societies, the majority of adults regularly consume alcohol. However, only a small proportion develops alcohol addiction. Individuals at risk often show a high sensation-seeking/low-anxiety behavioural phenotype. Here we asked which role EF hand domain containing 2 (EFhd2; Swiprosin-1) plays in the control of alcohol addiction-associated behaviours. EFhd2 knockout (KO) mice drink more alcohol than controls and spontaneously escalate their consumption. This coincided with a sensation-seeking and low-anxiety phenotype. A reversal of the behavioural phenotype with ß-carboline, an anxiogenic inverse benzodiazepine receptor agonist, normalized alcohol preference in EFhd2 KO mice, demonstrating an EFhd2-driven relationship between personality traits and alcohol preference. These findings were confirmed in a human sample where we observed a positive association of the EFhd2 single-nucleotide polymorphism rs112146896 with lifetime drinking and a negative association with anxiety in healthy adolescents. The lack of EFhd2 reduced extracellular dopamine levels in the brain, but enhanced responses to alcohol. In confirmation, gene expression analysis revealed reduced tyrosine hydroxylase expression and the regulation of genes involved in cortex development, Eomes and Pax6, in EFhd2 KO cortices. These findings were corroborated in Xenopus tadpoles by EFhd2 knockdown. Magnetic resonance imaging (MRI) in mice showed that a lack of EFhd2 reduces cortical volume in adults. Moreover, human MRI confirmed the negative association between lifetime alcohol drinking and superior frontal gyrus volume. We propose that EFhd2 is a conserved resilience factor against alcohol consumption and its escalation, working through Pax6/Eomes. Reduced EFhd2 function induces high-risk personality traits of sensation-seeking/low anxiety associated with enhanced alcohol consumption, which may be related to cortex function.

Genomic architecture of human neuroanatomical diversity.

Human brain anatomy is strikingly diverse and highly inheritable: genetic factors may explain up to 80% of its variability. Prior studies have tried to detect genetic variants with a large effect on neuroanatomical diversity, but those currently identified account for <5% of the variance. Here, based on our analyses of neuroimaging and whole-genome genotyping data from 1765 subjects, we show that up to 54% of this heritability is captured by large numbers of single-nucleotide polymorphisms of small-effect spread throughout the genome, especially within genes and close regulatory regions. The genetic bases of neuroanatomical diversity appear to be relatively independent of those of body size (height), but shared with those of verbal intelligence scores. The study of this genomic architecture should help us better understand brain evolution and disease.

Single nucleotide polymorphism in the neuroplastin locus associates with cortical thickness and intellectual ability in adolescents.

Despite the recognition that cortical thickness is heritable and correlates with intellectual ability in children and adolescents, the genes contributing to individual differences in these traits remain unknown. We conducted a large-scale association study in 1583 adolescents to identify genes affecting cortical thickness. Single-nucleotide polymorphisms (SNPs; n=54,837) within genes whose expression changed between stages of growth and differentiation of a human neural stem cell line were selected for association analyses with average cortical thickness. We identified a variant, rs7171755, associating with thinner cortex in the left hemisphere (P=1.12 × 10(-)(7)), particularly in the frontal and temporal lobes. Localized effects of this SNP on cortical thickness differently affected verbal and nonverbal intellectual abilities. The rs7171755 polymorphism acted in cis to affect expression in the human brain of the synaptic cell adhesion glycoprotein-encoding gene NPTN. We also found that cortical thickness and NPTN expression were on average higher in the right hemisphere, suggesting that asymmetric NPTN expression may render the left hemisphere more sensitive to the effects of NPTN mutations, accounting for the lateralized effect of rs7171755 found in our study. Altogether, our findings support a potential role for regional synaptic dysfunctions in forms of intellectual deficits.

Resilience and corpus callosum microstructure in adolescence.

BACKGROUND: Resilience is the capacity of individuals to resist mental disorders despite exposure to stress. Little is known about its neural underpinnings. The putative variation of white-matter microstructure with resilience in adolescence, a critical period for brain maturation and onset of high-prevalence mental disorders, has not been assessed by diffusion tensor imaging (DTI). Lower fractional anisotropy (FA) though, has been reported in the corpus callosum (CC), the brain's largest white-matter structure, in psychiatric and stress-related conditions. We hypothesized that higher FA in the CC would characterize stress-resilient adolescents. METHOD: Three groups of adolescents recruited from the community were compared: resilient with low risk of mental disorder despite high exposure to lifetime stress (n = 55), at-risk of mental disorder exposed to the same level of stress (n = 68), and controls (n = 123). Personality was assessed by the NEO-Five Factor Inventory (NEO-FFI). Voxelwise statistics of DTI values in CC were obtained using tract-based spatial statistics. Regional projections were identified by probabilistic tractography. RESULTS: Higher FA values were detected in the anterior CC of resilient compared to both non-resilient and control adolescents. FA values varied according to resilience capacity. Seed regional changes in anterior CC projected onto anterior cingulate and frontal cortex. Neuroticism and three other NEO-FFI factor scores differentiated non-resilient participants from the other two groups. CONCLUSION: High FA was detected in resilient adolescents in an anterior CC region projecting to frontal areas subserving cognitive resources. Psychiatric risk was associated with personality characteristics. Resilience in adolescence may be related to white-matter microstructure.

White-matter microstructure and gray-matter volumes in adolescents with subthreshold bipolar symptoms.

Abnormalities in white-matter (WM) microstructure, as lower fractional anisotropy (FA), have been reported in adolescent-onset bipolar disorder and in youth at familial risk for bipolarity. We sought to determine whether healthy adolescents with subthreshold bipolar symptoms (SBP) would have early WM microstructural alterations and whether those alterations would be associated with differences in gray-matter (GM) volumes. Forty-two adolescents with three core manic symptoms and no psychiatric diagnosis, and 126 adolescents matched by age and sex, with no psychiatric diagnosis or symptoms, were identified after screening the IMAGEN database of 2223 young adolescents recruited from the general population. After image quality control, voxel-wise statistics were performed on the diffusion parameters using tract-based spatial statistics in 25 SBP adolescents and 77 controls, and on GM and WM images using voxel-based morphometry in 30 SBP adolescents and 106 controls. As compared with healthy controls, adolescents with SBP displayed lower FA values in a number of WM tracts, particularly in the corpus callosum, cingulum, bilateral superior and inferior longitudinal fasciculi, uncinate fasciculi and corticospinal tracts. Radial diffusivity was mainly higher in posterior parts of bilateral superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculi and right cingulum. As compared with controls, SBP adolescents had lower GM volume in the left anterior cingulate region. This is the first study to investigate WM microstructure and GM morphometric variations in adolescents with SBP. The widespread FA alterations in association and projection tracts, associated with GM changes in regions involved in mood disorders, suggest altered structural connectivity in those adolescents.

Cortical thickness of superior frontal cortex predicts impulsiveness and perceptual reasoning in adolescence.

Impulsiveness is a pivotal personality trait representing a core domain in all major personality inventories. Recently, impulsiveness has been identified as an important modulator of cognitive processing, particularly in tasks that require the processing of large amounts of information. Although brain imaging studies have implicated the prefrontal cortex to be a common underlying representation of impulsiveness and related cognitive functioning, to date a fine-grain and detailed morphometric analysis has not been carried out. On the basis of ahigh-resolution magnetic resonance scans acquired in 1620 healthy adolescents (IMAGEN), the individual cortical thickness (CT) was estimated. Correlations between Cloninger's impulsiveness and CT were studied in an entire cortex analysis. The cluster identified was tested for associations with performance in perceptual reasoning tasks of the Wechsler Intelligence Scale for Children (WISC IV). We observed a significant inverse correlation between trait impulsiveness and CT of the left superior frontal cortex (SFC; Monte Carlo Simulation P<0.01). CT within this cluster correlated with perceptual reasoning scores (Bonferroni corrected) of the WISC IV. On the basis of a large sample of adolescents, we identified an extended area in the SFC as a correlate of impulsiveness, which appears to be in line with the trait character of this prominent personality facet. The association of SFC thickness with perceptual reasoning argues for a common neurobiological basis of personality and specific cognitive domains comprising attention, spatial reasoning and response selection. The results may facilitate the understanding of the role of impulsiveness in several psychiatric disorders associated with prefrontal dysfunctions and cognitive deficits.

Brain activation during fear conditioning in humans depends on genetic variations related to functioning of the hypothalamic-pituitary-adrenal axis: first evidence from two independent subsamples.

BACKGROUND: Enhanced acquisition and delayed extinction of fear conditioning are viewed as major determinants of anxiety disorders, which are often characterized by a dysfunctional hypothalamic-pituitary-adrenal (HPA) axis. METHOD: In this study we employed cued fear conditioning in two independent samples of healthy subjects (sample 1: n=60, sample 2: n=52). Two graphical shapes served as conditioned stimuli and painful electrical stimulation as the unconditioned stimulus. In addition, guided by findings from published animal studies on HPA axis-related genes in fear conditioning, we examined variants of the glucocorticoid receptor and corticotropin-releasing hormone receptor 1 genes. RESULTS: Variation in these genes showed enhanced amygdala activation during the acquisition and reduced prefrontal activation during the extinction of fear as well as altered amygdala-prefrontal connectivity. CONCLUSIONS: This is the first demonstration of the involvement of genes related to the HPA axis in human fear conditioning.

Parental education and youth suicidal behaviours: a systematic review and meta-analysis.

AIMS: Lower parental education has been linked to adverse youth mental health outcomes. However, the relationship between parental education and youth suicidal behaviours remains unclear. We explored the association between parental education and youth suicidal ideation and attempts, and examined whether sociocultural contexts moderate such associations. METHODS: We conducted a systematic review and meta-analysis with a systematic literature search in PubMed, PsycINFO, Medline and Embase from 1900 to December 2020 for studies with participants aged 0-18, and provided quantitative data on the association between parental education and youth suicidal ideation and attempts (death included). Only articles published in English in peer-reviewed journals were considered. Two authors independently assessed eligibility of the articles. One author extracted data [e.g. number of cases and non-cases in each parental education level, effect sizes in forms of odds ratios (ORs) or beta coefficients]. We then calculated pooled ORs using a random-effects model and used moderator analysis to investigate heterogeneity. RESULTS: We included a total of 59 articles (63 study samples, totalling 2 738 374 subjects) in the meta-analysis. Lower parental education was associated with youth suicidal attempts [OR = 1.12, 95% Confidence Interval (CI) = 1.04-1.21] but not with suicidal ideation (OR = 1.05, 95% CI = 0.98-1.12). Geographical region and country income level moderated the associations. Lower parental education was associated with an increased risk of youth suicidal attempts in Northern America (OR = 1.26, 95% CI = 1.10-1.45), but with a decreased risk in Eastern and South-Eastern Asia (OR = 0.72, 95% CI = 0.54-0.96). An association of lower parental education and increased risk of youth suicidal ideation was present in high- income countries (HICs) (OR = 1.14, 95% CI = 1.05-1.25), and absent in low- and middle-income countries (LMICs) (OR = 0.91, 95% CI = 0.77-1.08). CONCLUSIONS: The association between youth suicidal behaviours and parental education seems to differ across geographical and economical contexts, suggesting that cultural, psychosocial or biological factors may play a role in explaining this association. Although there was high heterogeneity in the studies reviewed, this evidence suggests that the role of familial sociodemographic characteristics in youth suicidality may not be universal. This highlights the need to consider cultural, as well as familial factors in the clinical assessment and management of youth's suicidal behaviours in our increasingly multicultural societies, as well as in developing prevention and intervention strategies for youth suicide.

Boys do it the right way: sex-dependent amygdala lateralization during face processing in adolescents.

Previous studies have observed a sex-dependent lateralization of amygdala activation related to emotional memory. Specifically, it was shown that the activity of the right amygdala correlates significantly stronger with memory for images judged as arousing in men than in women, and that there is a significantly stronger relationship in women than in men between activity of the left amygdala and memory for arousing images. Using a large sample of 235 male adolescents and 235 females matched for age and handedness, we investigated the sex-specific lateralization of amygdala activation during an emotional face perception fMRI task. Performing a formal sex by hemisphere analysis, we observed in males a significantly stronger right amygdala activation as compared to females. Our results indicate that adolescents display a sex-dependent lateralization of amygdala activation that is also present in basic processes of emotional perception. This finding suggests a sex-dependent development of human emotion processing and may further implicate possible etiological pathways for mental disorders most frequent in adolescent males (i.e., conduct disorder).

The IMAGEN study: reinforcement-related behaviour in normal brain function and psychopathology.

A fundamental function of the brain is to evaluate the emotional and motivational significance of stimuli and to adapt behaviour accordingly. The IMAGEN study is the first multicentre genetic-neuroimaging study aimed at identifying the genetic and neurobiological basis of individual variability in impulsivity, reinforcer sensitivity and emotional reactivity, and determining their predictive value for the development of frequent psychiatric disorders. Comprehensive behavioural and neuropsychological characterization, functional and structural neuroimaging and genome-wide association analyses of 2000 14-year-old adolescents are combined with functional genetics in animal and human models. Results will be validated in 1000 adolescents from the Canadian Saguenay Youth Study. The sample will be followed up longitudinally at the age of 16 years to investigate the predictive value of genetics and intermediate phenotypes for the development of frequent psychiatric disorders. This review describes the strategies the IMAGEN consortium used to meet the challenges posed by large-scale multicentre imaging-genomics investigations. We provide detailed methods and Standard Operating Procedures that we hope will be helpful for the design of future studies. These include standardization of the clinical, psychometric and neuroimaging-acquisition protocols, development of a central database for efficient analyses of large multimodal data sets and new analytic approaches to large-scale genetic neuroimaging analyses.

Complement-dependent B-cell activation by cobra venom factor and other mitogens?

It has been proposed that two distinct signals are required for the triggering of the precursors of antibody-forming bone marrow-derived cells (B cells): (a) the binding of antigen or of a mitogen to the corresponding receptor sites on B-cell membranes and (b) the interaction of activated C3 with the C3 receptor of B lymphocytes. There is growing evidence that B-cell mitogens and T (thymus-derived cell)-independent antigens are capable of activating the alternate pathway of the complement system (bypass). Therefore, the effect of another potent bypass inducer was investigated with regard to B-cell activation and the role of C3. Purified, pyrogen-free cobra venom factor was mitogenic for both T and B lymphocytes (cortisone-resistant mouse thymus cells and lymph node lymphocytes from congenitally athymic mice). Venom factor could substitute for T cells by restoring the potential of antibody formation to sheep red blood cells in mouse B-cell cultures supplemented with macrophages or 2-mercaptoethanol. Venom factor may be capable of conferring activated C3 to the C3 receptor of B lymphocytes: preincubation of lymphoid cells with homologous serum or plasma, 10 mM EDTA, and sepharose-coupled venom factor converted with serum to an enzyme active against C3, inhibited their capacity to subsequently form rosettes with sheep erythrocytes sensitized with amboceptor and C5-deficient mouse complement. In the absence of EDTA, preincubation of freshly prepared B-cell suspensions with C3-sufficient homologous serum also blocked their subsequent interaction with complement-sensitized erythrocytes and at the same time rendered them reactive to an otherwise T-cell-specific mitogen. Moreover, mitogen induced B-cell proliferation in lymph node (but not in spleen) cell cultures, appeared to depend on the availability of exogenous C3: zymosan-absorbed fetal bovine serum (only 8.3% site-forming units remaining) supported T-cell activation by phytohemagglutinin, concanavalin A, and venom factor, but failed to sustain B-cell stimulation by pokeweed mitogen, lipopolysaccharide, and venom factor. T-cell-dependent antibody formation in composite cultures containing T cells or T-cell-substituting B-cell mitogens, B cells, and macrophages, always required the presence of C3-sufficient serum.