Prefrontal cortical thinning links to negative symptoms in schizophrenia via the ENIGMA consortium.

BACKGROUND: Our understanding of the complex relationship between schizophrenia symptomatology and etiological factors can be improved by studying brain-based correlates of schizophrenia. Research showed that impairments in value processing and executive functioning, which have been associated with prefrontal brain areas [particularly the medial orbitofrontal cortex (MOFC)], are linked to negative symptoms. Here we tested the hypothesis that MOFC thickness is associated with negative symptom severity. METHODS: This study included 1985 individuals with schizophrenia from 17 research groups around the world contributing to the ENIGMA Schizophrenia Working Group. Cortical thickness values were obtained from T1-weighted structural brain scans using FreeSurfer. A meta-analysis across sites was conducted over effect sizes from a model predicting cortical thickness by negative symptom score (harmonized Scale for the Assessment of Negative Symptoms or Positive and Negative Syndrome Scale scores). RESULTS: Meta-analytical results showed that left, but not right, MOFC thickness was significantly associated with negative symptom severity (ß std = -0.075; p = 0.019) after accounting for age, gender, and site. This effect remained significant (p = 0.036) in a model including overall illness severity. Covarying for duration of illness, age of onset, antipsychotic medication or handedness weakened the association of negative symptoms with left MOFC thickness. As part of a secondary analysis including 10 other prefrontal regions further associations in the left lateral orbitofrontal gyrus and pars opercularis emerged. CONCLUSIONS: Using an unusually large cohort and a meta-analytical approach, our findings point towards a link between prefrontal thinning and negative symptom severity in schizophrenia. This finding provides further insight into the relationship between structural brain abnormalities and negative symptoms in schizophrenia.

Frequency-Domain Multiplexing Readout with a Self-Trigger System for Pulse Signals from Kinetic Inductance Detectors.

We present the development of a frequency-domain multiplexing readout of kinetic inductance detectors (KIDs) for pulse signals with a self-trigger system. The KIDs consist of an array of superconducting resonators that have different resonant frequencies individually, allowing us to read out multiple channels in the frequency domain with a single wire using a microwave-frequency comb. The energy deposited to the resonators break Cooper pairs, changing the kinetic inductance and, hence, the amplitude and the phase of the probing microwaves. For some applications such as X-ray detections, the deposited energy is detected as a pulse signal shaped by the time constants of the quasiparticle lifetime, the resonator quality factor, and the ballistic phonon lifetime in the substrate, ranging from microseconds to milliseconds. A readout system commonly used converts the frequency-domain data to the time-domain data. For the short pulse signals, the data rate may exceed the data transfer bandwidth, as the short time constant pulses require us to have a high sampling rate. In order to overcome this circumstance, we have developed a KID readout system that contains a self-trigger system to extract relevant signal data and reduces the total data rate with a commercial off-the-shelf FPGA board. We have demonstrated that the system can read out pulse signals of 15 resonators simultaneously with about 10 Hz event rate by irradiating α particles from 241 Am to the silicon substrate on whose surface aluminum KID resonators are formed.

Positive symptoms associate with cortical thinning in the superior temporal gyrus via the ENIGMA Schizophrenia consortium.

OBJECTIVE: Based on the role of the superior temporal gyrus (STG) in auditory processing, language comprehension and self-monitoring, this study aimed to investigate the relationship between STG cortical thickness and positive symptom severity in schizophrenia. METHOD: This prospective meta-analysis includes data from 1987 individuals with schizophrenia collected at seventeen centres around the world that contribute to the ENIGMA Schizophrenia Working Group. STG thickness measures were extracted from T1-weighted brain scans using FreeSurfer. The study performed a meta-analysis of effect sizes across sites generated by a model predicting left or right STG thickness with a positive symptom severity score (harmonized SAPS or PANSS-positive scores), while controlling for age, sex and site. Secondary models investigated relationships between antipsychotic medication, duration of illness, overall illness severity, handedness and STG thickness. RESULTS: Positive symptom severity was negatively related to STG thickness in both hemispheres (left: ßstd = -0.052; P = 0.021; right: ßstd = -0.073; P = 0.001) when statistically controlling for age, sex and site. This effect remained stable in models including duration of illness, antipsychotic medication or handedness. CONCLUSION: Our findings further underline the important role of the STG in hallmark symptoms in schizophrenia. These findings can assist in advancing insight into symptom-relevant pathophysiological mechanisms in schizophrenia.

High-resolution copy number variation analysis of schizophrenia in Japan.

Recent schizophrenia (SCZ) studies have reported an increased burden of de novo copy number variants (CNVs) and identified specific high-risk CNVs, although with variable phenotype expressivity. However, the pathogenesis of SCZ has not been fully elucidated. Using array comparative genomic hybridization, we performed a high-resolution genome-wide CNV analysis on a mainly (92%) Japanese population (1699 SCZ cases and 824 controls) and identified 7066 rare CNVs, 70.0% of which were small (<100 kb). Clinically significant CNVs were significantly more frequent in cases than in controls (odds ratio=3.04, P=9.3 × 10-9, 9.0% of cases). We confirmed a significant association of X-chromosome aneuploidies with SCZ and identified 11 de novo CNVs (e.g., MBD5 deletion) in cases. In patients with clinically significant CNVs, 41.7% had a history of congenital/developmental phenotypes, and the rate of treatment resistance was significantly higher (odds ratio=2.79, P=0.0036). We found more severe clinical manifestations in patients with two clinically significant CNVs. Gene set analysis replicated previous findings (e.g., synapse, calcium signaling) and identified novel biological pathways including oxidative stress response, genomic integrity, kinase and small GTPase signaling. Furthermore, involvement of multiple SCZ candidate genes and biological pathways in the pathogenesis of SCZ was suggested in established SCZ-associated CNV loci. Our study shows the high genetic heterogeneity of SCZ and its clinical features and raises the possibility that genomic instability is involved in its pathogenesis, which may be related to the increased burden of de novo CNVs and variable expressivity of CNVs.

Abnormal asymmetries in subcortical brain volume in schizophrenia.

Subcortical structures, which include the basal ganglia and parts of the limbic system, have key roles in learning, motor control and emotion, but also contribute to higher-order executive functions. Prior studies have reported volumetric alterations in subcortical regions in schizophrenia. Reported results have sometimes been heterogeneous, and few large-scale investigations have been conducted. Moreover, few large-scale studies have assessed asymmetries of subcortical volumes in schizophrenia. Here, as a work completely independent of a study performed by the ENIGMA consortium, we conducted a large-scale multisite study of subcortical volumetric differences between patients with schizophrenia and controls. We also explored the laterality of subcortical regions to identify characteristic similarities and differences between them. T1-weighted images from 1680 healthy individuals and 884 patients with schizophrenia, obtained with 15 imaging protocols at 11 sites, were processed with FreeSurfer. Group differences were calculated for each protocol and meta-analyzed. Compared with controls, patients with schizophrenia demonstrated smaller bilateral hippocampus, amygdala, thalamus and accumbens volumes as well as intracranial volume, but larger bilateral caudate, putamen, pallidum and lateral ventricle volumes. We replicated the rank order of effect sizes for subcortical volumetric changes in schizophrenia reported by the ENIGMA consortium. Further, we revealed leftward asymmetry for thalamus, lateral ventricle, caudate and putamen volumes, and rightward asymmetry for amygdala and hippocampal volumes in both controls and patients with schizophrenia. Also, we demonstrated a schizophrenia-specific leftward asymmetry for pallidum volume. These findings suggest the possibility of aberrant laterality in neural pathways and connectivity patterns related to the pallidum in schizophrenia.

Imaging genetics and psychiatric disorders.

Imaging genetics is an integrated research method that uses neuroimaging and genetics to assess the impact of genetic variation on brain function and structure. Imaging genetics is both a tool for the discovery of risk genes for psychiatric disorders and a strategy for characterizing the neural systems affected by risk gene variants to elucidate quantitative and mechanistic aspects of brain function implicated in psychiatric disease. Early studies of imaging genetics included association analyses between brain morphology and single nucleotide polymorphisms whose function is well known, such as catechol-Omethyltransferase (COMT) and brain-derived neurotrophic factor (BDNF). GWAS of psychiatric disorders have identified genes with unknown functions, such as ZNF804A, and imaging genetics has been used to investigate clues of the biological function of these genes. The difficulty in replicating the findings of studies with small sample sizes has motivated the creation of largescale collaborative consortiums, such as ENIGMA, CHARGE and IMAGEN, to collect thousands of images. In a genome-wide association study, the ENIGMA consortium successfully identified common variants in the genome associated with hippocampal volume at 12q24, and the CHARGE consortium replicated this finding. The new era of imaging genetics has just begun, and the next challenge we face is the discovery of small effect size signals from large data sets obtained from genetics and neuroimaging. New methods and technologies for data reduction with appropriate statistical thresholds, such as polygenic analysis and parallel independent component analysis (ICA), are warranted. Future advances in imaging genetics will aid in the discovery of genes and provide mechanistic insight into psychiatric disorders.

Common variants at 1p36 are associated with superior frontal gyrus volume.

The superior frontal gyrus (SFG), an area of the brain frequently found to have reduced gray matter in patients with schizophrenia, is involved in self-awareness and emotion, which are impaired in schizophrenia. However, no genome-wide association studies of SFG volume have investigated in patients with schizophrenia. To identify single-nucleotide polymorphisms (SNPs) associated with SFG volumes, we demonstrated a genome-wide association study (GWAS) of gray matter volumes in the right or left SFG of 158 patients with schizophrenia and 378 healthy subjects. We attempted to bioinformatically ascertain the potential effects of the top hit polymorphism on the expression levels of genes at the genome-wide region. We found associations between five variants on 1p36.12 and the right SFG volume at a widely used benchmark for genome-wide significance (P<5.0 × 10(-8)). The strongest association was observed at rs4654899, an intronic SNP in the eukaryotic translation initiation factor 4 gamma, 3 (EIF4G3) gene on 1p36.12 (P=7.5 × 10(-9)). No SNP with genome-wide significance was found in the volume of the left SFG (P>5.0 × 10(-8)); however, the rs4654899 polymorphism was identified as the locus with the second strongest association with the volume of the left SFG (P=1.5 × 10(-6)). In silico analyses revealed a proxy SNP of rs4654899 had effect on gene expression of two genes, HP1BP3 lying 3' to EIF4G3 (P=7.8 × 10(-6)) and CAPN14 at 2p (P=6.3 × 10(-6)), which are expressed in moderate-to-high levels throughout the adult human SFG. These results contribute to understand genetic architecture of a brain structure possibly linked to the pathophysiology of schizophrenia.

Increased and decreased expression of CD69 and CD23, respectively, in gravity-stressed lymphocytes.

BACKGROUND: Recent studies have shown that gravity-changing stress modulates expression levels of cell surface molecules on human lymphocytes. However, previous in vitro microgravity studies have been performed with lymphocytes treated with mitogenic agents. HYPOTHESIS: The aim of the study was to test if exposure of cells to gravity-changing stress alone alters the expression levels of cell surface molecules. Specifically, we examined whether the expression of activation markers is altered after exposure of lymphocytes to combinations of microgravity and hypergravity. METHODS: We used free-fall in parabolic flight for human subjects and a drop-shaft to expose peripheral blood mononuclear cells (PBMC) to gravity-changing stress. After such exposure, PBMC were isolated, and expression levels of CD69, CD23 and CD38 were estimated using three-color flow cytometry. RESULTS: Increased percentages of CD69-positive cells were observed with PBMC from 3 of 4 volunteers who undertook 10 parabolic flights. Exposure of blood to gravity-changing stress in the drop-shaft increased both ratios of CD69-positive cells and levels of CD69 expression on T and B cells. In contrast, the percentages of CD23-positive B cells was decreased. However, gravity-changing stress was not always followed by significant alteration in CD38 expression. CONCLUSIONS: Our findings suggest that CD69 and CD23 might be useful markers that are up- and down-regulated, respectively, after exposure of lymphocytes to gravity-changing stress.

Mutagenicity of bisphenol A and its suppression by interferon-alpha in human RSa cells.

Bisphenol A is used as a monomer in the production of polycarbonate plastic products. The widespread use of bisphenol A has raised concerns about its effects in humans. Since there is little information on the mutagenic potential of the chemical, the mutagenicity of bisphenol A was tested using human RSa cells, which has been utilized for identification of novel mutagens. In genomic DNA from cells treated with bisphenol A at concentrations ranging from 1x10(-7) to 1x10(-5)M, base substitution mutations at K-ras codon 12 were detected using PCR and differential dot-blot hybridization with mutant probes. Mutations were also detected using the method of peptide nucleic acid (PNA)-mediated PCR clamping. The latter method enabled us to detect the mutation in bisphenol A-treated cells at a dose (1x10(-8)M) equivalent to that typically found in the environment. Induction of ouabain-resistant (Oua(R)) phenotypic mutation was also found in cells treated with 1x10(-7) and 1x10(-5)M of bisphenol A. The induction of K-ras codon 12 mutations and Oua(R) mutations was suppressed by pretreating RSa cells with human interferon (HuIFN)-alpha prior to bisphenol A treatment. The cells treated with bisphenol A at the concentration of 1x10(-6)M elicited unscheduled DNA synthesis (UDS). These findings suggested that bisphenol A has mutagenicity in RSa cells as well as mutagens that have been tested in these cells, and furthermore, that a combination of the PNA-mediated PCR clamping method with the human RSa cell line may be used as an assay system for screening the mutagenic chemicals at very low doses.

Preoperative immunosuppression: its relationship with high morbidity and mortality in patients receiving thoracic esophagectomy.

The operative procedure for thoracic esophageal cancer, including thoracotomy, laparotomy, and three-field lymph node dissection, is a particularly stressful surgery that is characterized by high morbidity and mortality. The aim of this study was to evaluate the immunologic and nutritional states of patients to determine possible predictive factors of morbidity and mortality in patients receiving thoracic esophagectomy. Patients receiving thoracic esophagectomy were retrospectively divided into two groups. One group had postoperative infectious complications (group C+, n = 27), and the other had no complications (group C-, n = 76). They were treated with total parenteral nutrition or enteral nutrition providing 35-40 kcal. kg(-1). d(-1) of energy and 1.3-1.5 kcal. kg(-1). d(-1) of amino acids throughout the study period. The phytohemagglutinin (PHA)- and concanavalin A (Con A)-induced proliferation of peripheral blood mononuclear cells (PBMC) from the patients were measured before and at days 7 and 21 after the operation. Serum albumin, prealbumin, transferrin, the retinol binding protein, and the C-reactive protein were also evaluated. Three patients out of 27 in group C+ died because of severe infectious complications, whereas none of patients was fatal in group C-. PHA- and Con A-induced proliferation of PBMC was significantly low before the operation and remained suppressed on the 21st postoperative day in group C+. No significant difference was observed in nutritional status during the perioperative days between the two groups. Our results indicate that esophageal cancer patients with preoperative suppression of the cell-mediated immunity can be identified as a higher risk population in the postoperative period. When adequate nutrition is received, however, the correlation between nutritional status and mortality disappears.

Search for UV-responsive genes in human cells by differential mRNA display: involvement of human ras-related GTP-binding protein, Rheb, in UV susceptibility.

The search for genes responsible for the sensitivity of human cells to cell-killing effects of UV is an important area of biological research. To identify candidate genes responsible for UV sensitization, levels of mRNA expression were compared between UV-sensitive RSa cells and UV-resistant variant UV(r)-1 cells, using a differential display method and Northern blot analysis. Messenger RNA expression levels of human Ras homologue enriched in brain (Rheb) and/or a Rheb-like gene were up-regulated and slightly decreased in UV-irradiated RSa and UV(r)-1 cells, compared to in mock-irradiated cells, respectively. RSa and UV(r)-1 cells, both of which were treated with antisense oligonucleotides for Rheb RNA, exhibited an increased resistance to UV cell-killing. It remains unclear why UV(r)-1 cells are resistant to UV yet express Rheb mRNA at high levels. However, the results of antisense experiments together with the up-regulation in UV-irradiated RSa cells, suggest that Rheb is involved in the UV sensitization of both cells to UV cell-killing.

Modulating effects of the feeding route on stress response and endotoxin translocation in severely stressed patients receiving thoracic esophagectomy.

Experimental studies have demonstrated that the route of nutritional supply impacts the systemic metabolic responses after surgical injury. Intestinal mucosal atrophy, as induced by total parenteral nutrition (TPN) or prolonged bowel rest, has been reported to enhance bowel endotoxin translocation. The operative procedure for thoracic esophageal cancer, including thoracotomy, laparotomy, and three-field lymph-node dissection, is a particularly stressful surgery that requires long-term aggressive nutritional support and often results in the postoperative hypermetabolic state, leading to perturbation of postoperative immune function. Interleukin-6 (IL-6) plays an important role in host inflammatory responses, whereas IL-10 is linked to suppression of cellular immunity. The aim of this study was to investigate how the antecedent nutritional routes influence systemic IL-6 and IL-10 responses and endotoxin translocation after an operation for thoracic esophageal cancer. Twenty-nine patients who underwent esophagectomy with three-field lymphadenectomy were investigated. They were assigned to groups receiving either TPN (n = 18) or enteral nutrition (EN; n = 11) providing 35 kcal x kg(-1) x d(-1) of energy and approximately 1.2-1.5 g x kg(-1) x d(-1) of amino acids. These nutritional supports were conducted from 1 wk before the operation to 14 d after the operation. Serum IL-6, IL-10, and endotoxin concentration were measured before and during the operation and at 2 h and 1, 3, and 7 d after the operation. IL-6 in sera was significantly higher after the operation in both groups. In the EN group, however, significantly less IL-6 production was observed on the third and seventh postoperative days when compared with those patients in the TPN group. Similarly, serum IL-10 concentration in the TPN group showed a significantly higher level than that in the EN group. Serum IL-6 showed a significant positive correlation with IL-10 at 2 h and at 7 d after the operation, suggesting that the reduced inflammatory responses were related to the inhibition of the development of postoperative immunosuppression. Endotoxin concentration in sera was significantly lower in the EN group after the operation than in the TPN group. Perioperative EN provides better regulation of inflammatory cytokine responses and may contribute less to immunosuppression after major surgery than parenteral nutrition. The attenuated production of endotoxin induced by EN may play an important role in these phenomena.

Increase in ultraviolet sensitivity by overexpression of calpastatin in ultraviolet-resistant UVr-1 cells derived from ultraviolet-sensitive human RSa cells.

Human RSa cells are highly sensitive to apoptotic-like cell death by ultraviolet irradiation (UV) while UVr-1 cells are their variant with an increased resistance to UV. Three days after UV at 10 J/m2, the viability of RSa cells was approximately 17% while that of UVr-1 cells was 65%. This different survival might reflect apoptotic cell death since apoptosis-specific DNA ladder was more clearly observed in RSa cells than in UVr-1 cells after UV. Addition of ALLN/calpain inhibitor I to the culture medium after UV resulted in similar survival (14 - 18%) between RSa and UVr-1 cells. Immunoblot analysis showed down-regulation of protein kinase CTheta, Src, Bax and mu-calpain after UV was more prominent in UVr-1 than in RSa cells. Activated mu-calpain appeared within 1 h post-UV only in UVr-1 cells. The expression of calpastatin, a specific endogenous inhibitor of calpain, was higher in RSa than in UVr-1 cells. To further examine the role of calpain in UV-induced cell death, cDNA of human calpastatin was transfected into UVr-1 cells. The results showed that overexpression of calpastatin suppressed down-regulation of Src, mu-calpain and Bax. Concomitantly, colony survival after UV was reduced in calpastatin-transfected cells as compared to vector control cells. Our results suggest that activation of calpain might account for, at least in part, the lower susceptibility to UV-induced cell death in UVr-1 cells.

Low levels of NPM gene expression in UV-sensitive human cell lines.

Nucleophosmin (NPM) is a major nuclear matrix protein associated with neoplastic growth in various cell types. We recently suggested that expression of the NPM gene is involved in an increased resistance to UV irradiation in human cells against the cell-killing effects of UV (mainly 254nm wavelength far-ultraviolet ray) [Y. Higuchi, K. Kita, H. Nakanishi, X-L. Wang, S. Sugaya, H. Tanzawa, H. Yamamori, K. Sugita, A. Yamaura, N. Suzuki, Biochem. Biophys. Res. Commun. 248 (1998) 597-602]. In the present study, expression levels of the NPM gene were examined in human cell lines with a high sensitivity to UV cell-killing. Cockayne syndrome patient-derived cell lines, CSAI and CSBI, and the Xeroderma pigmentosum patient-derived cell line, XP2OS(SV), XP13KY, XP3KA, XP6BE(SV), XP101OS and XP3BR(SV), have been investigated for their NPM mRNA expression with Northern blotting analysis. All of these UV-sensitive cells demonstrated lower expression levels compared with those of normal fibroblast cells, FF, or an UV-resistant cell line, UH(r)-10; quite a lower level of expression in XP205(SV) cells after UV irradiation in contrast to a distinguishable increase in the expression in UV(r)- cells. These results confirmed an intimate correlation between degree of UV sensitivity and expression levels of the NPM gene in human cells.