Polygenic risk associated with post-traumatic stress disorder onset and severity.

Post-traumatic stress disorder (PTSD) is a psychiatric illness with a highly polygenic architecture without large effect-size common single-nucleotide polymorphisms (SNPs). Thus, to capture a substantial portion of the genetic contribution, effects from many variants need to be aggregated. We investigated various aspects of one such approach that has been successfully applied to many traits, polygenic risk score (PRS) for PTSD. Theoretical analyses indicate the potential prediction ability of PRS. We used the latest summary statistics from the largest published genome-wide association study (GWAS) conducted by Psychiatric Genomics Consortium for PTSD (PGC-PTSD). We found that the PRS constructed for a cohort comprising veterans of recent wars (n = 244) explains a considerable proportion of PTSD onset (Nagelkerke R2 = 4.68%, P = 0.003) and severity (R2 = 4.35%, P = 0.0008) variances. However, the performance on an African ancestry sub-cohort was minimal. A PRS constructed with schizophrenia GWAS also explained a significant fraction of PTSD diagnosis variance (Nagelkerke R2 = 2.96%, P = 0.0175), confirming previously reported genetic correlation between the two psychiatric ailments. Overall, these findings demonstrate the important role polygenic analyses of PTSD will play in risk prediction models as well as in elucidating the biology of the disorder

Obsessive–compulsive disorder as a visual processing impairment

OCD has been hypothesized to involve the failures in both cognitive and behavioral inhibitory processes. There is evidence that the hyperactivation of cortical–subcortical pathways may be involved in the failure of these inhibitory systems associated with OCD. Despite this consensus on the role of frontal–subcortical pathways in OCD, recent studies have been showing that brain regions other than the frontal–subcortical loops may be needed to understand the different cognitive and emotional deficits in OCD. Some studies have been finding evidence for decreased metabolic activity in areas such as left inferior parietal and parieto- occipital junction suggesting the possible existence of visual processing deficits. While there has been inconsistent data regarding visual processing in OCD, recent studies have been claiming that these patients have abnormal patterns of visual processing social rich stimuli, particularly emotional arousing stimuli. Thus, in this article, we hypothesize that the fronto-subcortical activation consistently found in OCD may be due to a deactivation of occipital/parietal regions associated with visual-perceptual processing of incoming social rich stimuli. Additionally, this dissociation may be more evident as the emotional intensity of the social stimulus increases

Ensino, aprendizagem e novas tecnologias: relações entre abordagens teóricas clássicas e contemporâneas

The article aims to present a parallel between the classical and contemporary theories of teaching and learning with similar modern theories which make use of Information and Communication Digital Technologies (ICDT). A theoretical investigative study was carried out utilizing the qualitative research approach, with focus on identifying existing theories about teaching and learning with the usage of ICTs and their relations with the classical and contemporary theoretical approaches. It concludes by making a parallel between constructivist, cognitivist, humanist and socio-historical theories with constructionism and connectivism, highlighting the differences and similarities of classic and contemporary theories when put in contrast regarding modern ones.O artigo visa apresentar um paralelo entre as teorias clássicas e contemporâneas de ensino e aprendizagem com as teorias modernas de ensino e de aprendizagem com o uso das Tecnologias Digitais da Informação e Comunicação (TDIC). Foi realizado um estudo investigativo teórico, segundo a abordagem da pesquisa qualitativa, com vistas a identificar teorias existentes sobre ensino e aprendizagem com o uso das TDIC e suas relações com abordagens teóricas clássicas e contemporâneas. Conclui-se fazendo um paralelo entre as teorias construtivista, cognitivista, humanista e sócio-histórica com o construcionismo e o conectivismo, destacando proximidades e distanciamentos entre o grupo clássico e contemporâneo com a teoria moderna.Palavras chave: Teorias de Ensino e de Aprendizagem Clássicas; Teorias de Ensino e de Aprendizagem Contemporâneas; Teorias de Ensino e de Aprendizagem com Novas Tecnologia

Time of trauma prospectively affects PTSD symptom severity: The impact of circadian rhythms and cortisol.

A key feature of posttraumatic stress disorder (PTSD) is a disruption of hypothalamic-pituitary-adrenal (HPA) axis feedback sensitivity and cortisol levels. Despite known diurnal rhythmicity of cortisol, there has been little exploration of the circadian timing of the index trauma and consequent cortisol release. Stress-related glucocorticoid pulses have been shown to shift clocks in peripheral organs but not the suprachiasmatic nucleus, uncoupling the central and peripheral clocks. A sample of 425 participants was recruited in the Emergency Department following a DSM-IV-TR Criterion A trauma. The Zeitgeber time of the trauma was indexed in minutes since sunrise, which was hypothesized to covary with circadian blood cortisol levels (high around sunrise and decreasing over the day). Blood samples were collected M(SD)= 4.0(4.0) hours post-trauma. PTSD symptoms six months post-trauma were found to be negatively correlated with trauma time since sunrise (r(233) = -0.15, p = 0.02). The effect remained when adjusting for sex, age, race, clinician-rated severity, education, pre-trauma PTSD symptoms, and time of the blood draw (β = -0.21, p = 0.00057). Cortisol levels did not correlate with blood draw time, consistent with a masking effect of the acute stress response obscuring the underlying circadian rhythm. Interactions between trauma time and expression of NPAS2 (punadjusted=0.042) and TIMELESS (punadjusted=0.029) predicted six-month PTSD symptoms. The interaction of trauma time and cortisol concentration was significantly correlated with the expression of PER1 (padjusted=0.029). The differential effect of time of day on future symptom severity suggests a role of circadian effects in PTSD development, potentially through peripheral clock disruption

Childhood Trauma and COMT Genotype Interact to Increase Hippocampal Activation in Resilient Individuals

Both childhood trauma and a functional COMT genetic polymorphism have been associated with PTSD and depression; however, it is still unclear whether the two interact and how this interaction relates to long-term risk or resilience. Imaging and genotype data were collected on 73 highly traumatized women. DNA extracted from saliva was used to determine COMT genotype (Val/Val, n=38, Met carriers, n=35). Functional MRI data were collected during a Go/NoGo task to investigate the neurocircuitry underlying response inhibition. Self-report measures of adult and childhood trauma exposure, PTSD and depression symptom severity, and resilience were collected. Childhood trauma was found to interact with COMT genotype to impact inhibition-related hippocampal activation. In Met carriers, more childhood trauma was associated with decreased hippocampal activation, whereas in the Val/Val group childhood trauma was related to increased hippocampal activation. Second, hippocampal activation correlated negatively with PTSD and depression symptoms, and positively with trait resilience. Moreover, hippocampal activation mediated the relationship between childhood trauma and psychiatric risk or resilience in the Val/Val, but not in the Met-carrier group. These data reveal a potential mechanism by which childhood trauma and COMT genotype interact to increase risk for trauma-related psychopathology or resilience. Hippocampal recruitment during inhibition may improve the ability to use contextual information to guide behavior, thereby enhancing resilience in trauma-exposed individuals. This finding may contribute to early identification of individuals at risk, and suggests a mechanism that can be targeted in future studies aiming to prevent or limit negative outcomes

Inhibition of the p110α isoform of PI 3-kinase stimulates nonfunctional tumor angiogenesis

Understanding the direct, tumor cell–intrinsic effects of PI 3-kinase (PI3K) has been a key focus of research to date. Here, we report that cancer cell–extrinsic PI3K activity, mediated by the p110α isoform of PI3K, contributes in an unexpected way to tumor angiogenesis. In syngeneic mouse models, inactivation of stromal p110α led to increased vascular density, reduced vessel size, and altered pericyte coverage. This increased vascularity lacked functionality, correlating with enhanced tumor hypoxia and necrosis, and reduced tumor growth. The role of p110α in tumor angiogenesis is multifactorial, and includes regulation of proliferation and DLL4 expression in endothelial cells. p110α in the tumor stroma is thus a regulator of vessel formation, with p110α inactivation giving rise to nonfunctional angiogenesis, which can stunt tumor growth. This type of vascular aberration differs from vascular endothelial growth factor–centered antiangiogenesis therapies, which mainly lead to vascular pruning. Inhibition of p110α may thus offer a new antiangiogenic therapeutic opportunity in cancer

Frequency of pathogenic germline variants in pediatric medulloblastoma survivors.

BACKGROUND: Medulloblastoma is the most common malignant brain tumor in children. Most cases are sporadic, but well characterized germline alterations in APC, ELP1, GPR161, PTCH1, SUFU, and TP53 predispose to medulloblastoma. However, knowledge about pathogenic/likely pathogenic (P/LP) variants that predispose to medulloblastoma vary based on genes evaluated, patient demographics, and pathogenicity definitions. METHODS: Germline exome sequencing was conducted on 160 childhood survivors of medulloblastoma. Analyses focused on rare variants in 239 known cancer susceptibility genes (CSGs). P/LP variants were identified using ClinVar and InterVar. Variants of unknown significance in known medulloblastoma predisposing genes (APC, ELP1, GPR161, PTCH1, SUFU, TP53) were further classified for loss of function variants. We compared the frequency of P/LP variants in cases to that in 1,259 cancer-free adult controls. RESULTS: Twenty cases (12.5%) had a P/LP variant in an autosomal dominant CSG versus 5% in controls (p=1.0 x10-3), and 10 (6.3%) of these were P/LP variants in a known medulloblastoma gene, significantly greater than 0.2% observed in controls (p=1.4x10-8). The CSGs with the most P/LP variants in cases, and significantly higher than controls, were ELP1 (p=3.0x10-4) and SUFU (p=1.4x10-3). CONCLUSION: Approximately one in eight pediatric medulloblastoma survivors had an autosomal dominant P/LP CSG variant. We confirm several known associated genes and identify novel genes that may be important in medulloblastoma

Light-strand bias and enriched zones of embedded ribonucleotides are associated with DNA replication and transcription in the human-mitochondrial genome

Abundant ribonucleoside-triphosphate (rNTP) incorporation into DNA by DNA polymerases in the form of ribonucleoside monophosphates (rNMPs) is a widespread phenomenon in nature, resulting in DNA-structural change and genome instability. The rNMP distribution, characteristics, hotspots and association with DNA metabolic processes in human mitochondrial DNA (hmtDNA) remain mostly unknown. Here, we utilize the ribose-seq technique to capture embedded rNMPs in hmtDNA of six different cell types. In most cell types, the rNMPs are preferentially embedded on the light strand of hmtDNA with a strong bias towards rCMPs; while in the liver-tissue cells, the rNMPs are predominately found on the heavy strand. We uncover common rNMP hotspots and conserved rNMP-enriched zones across the entire hmtDNA, including in the control region, which links the rNMP presence to the frequent hmtDNA replication-failure events. We show a strong correlation between coding-sequence size and rNMP-embedment frequency per nucleotide on the non-template, light strand in all cell types, supporting the presence of transient RNA-DNA hybrids preceding light-strand replication. Moreover, we detect rNMP-embedment patterns that are only partly conserved across the different cell types and are distinct from those found in yeast mtDNA. The study opens new research directions to understand the biology of hmtDNA and genomic rNMPs.Graphical Abstrac

PACAP-PAC1R modulates fear extinction via the ventromedial hypothalamus

Exposure to traumatic stress can lead to fear dysregulation, which has been associated with posttraumatic stress disorder (PTSD). Previous work showed that a polymorphism in the PACAP-PAC1R (pituitary adenylate cyclase-activating polypeptide) system is associated with PTSD risk in women, and PACAP (ADCYAP1)-PAC1R (ADCYAP1R1) are highly expressed in the hypothalamus. Here, we show that female mice subjected to acute stress immobilization (IMO) have fear extinction impairments related to Adcyap1 and Adcyap1r1 mRNA upregulation in the hypothalamus, PACAP-c-Fos downregulation in the Medial Amygdala (MeA), and PACAP-FosB/ΔFosB upregulation in the Ventromedial Hypothalamus dorsomedial part (VMHdm). DREADD-mediated inhibition of MeA neurons projecting to the VMHdm during IMO rescues both PACAP upregulation in VMHdm and the fear extinction impairment. We also found that women with the risk genotype of ADCYAP1R1 rs2267735 polymorphism have impaired fear extinction

Inhibition of the p110α isoform of PI 3-kinase stimulates nonfunctional tumor angiogenesis

Understanding the direct, tumor cell–intrinsic effects of PI 3-kinase (PI3K) has been a key focus of research to date. Here, we report that cancer cell–extrinsic PI3K activity, mediated by the p110α isoform of PI3K, contributes in an unexpected way to tumor angiogenesis. In syngeneic mouse models, inactivation of stromal p110α led to increased vascular density, reduced vessel size, and altered pericyte coverage. This increased vascularity lacked functionality, correlating with enhanced tumor hypoxia and necrosis, and reduced tumor growth. The role of p110α in tumor angiogenesis is multifactorial, and includes regulation of proliferation and DLL4 expression in endothelial cells. p110α in the tumor stroma is thus a regulator of vessel formation, with p110α inactivation giving rise to nonfunctional angiogenesis, which can stunt tumor growth. This type of vascular aberration differs from vascular endothelial growth factor–centered antiangiogenesis therapies, which mainly lead to vascular pruning. Inhibition of p110α may thus offer a new antiangiogenic therapeutic opportunity in cancer