A Complex Network Approach to Topographical Connections

The neuronal networks in the mammals cortex are characterized by the coexistence of hierarchy, modularity, short and long range interactions, spatial correlations, and topographical connections. Particularly interesting, the latter type of organization implies special demands on the evolutionary and ontogenetic systems in order to achieve precise maps preserving spatial adjacencies, even at the expense of isometry. Although object of intensive biological research, the elucidation of the main anatomic-functional purposes of the ubiquitous topographical connections in the mammals brain remains an elusive issue. The present work reports on how recent results from complex network formalism can be used to quantify and model the effect of topographical connections between neuronal cells over a number of relevant network properties such as connectivity, adjacency, and information broadcasting. While the topographical mapping between two cortical modules are achieved by connecting nearest cells from each module, three kinds of network models are adopted for implementing intracortical connections (ICC), including random, preferential-attachment, and short-range networks. It is shown that, though spatially uniform and simple, topographical connections between modules can lead to major changes in the network properties, fostering more effective intercommunication between the involved neuronal cells and modules. The possible implications of such effects on cortical operation are discussed.Comment: 5 pages, 5 figure

Excitonic Effects and Optical Spectra of Single-Walled Carbon Nanotubes

Many-electron effects often dramatically modify the properties of reduced dimensional systems. We report calculations, based on an many-electron Green's function approach, of electron-hole interaction effects on the optical spectra of small-diameter single-walled carbon nanotubes. Excitonic effects qualitatively alter the optical spectra of both semiconducting and metallic tubes. Excitons are bound by ~ 1 eV in the semiconducting (8,0) tube and by ~ 100 meV in the metallic (3,3) tube. These large many-electron effects explain the discrepancies between previous theories and experiments.Comment: 6 pages, 3 figures, 2 table

Oscillator Strength of Metallic Carbon Nanotubes

Based on the tight binding method with hopping integral between the nearest-neighbor atoms, an oscillator strength \int_0^{\infty} \d \omega {\rm Re} \sigma (\omega) is discussed for armchair and metallic zigzag carbon nanotubes. The formulae of the oscillator strength are derived for both types of nanotubes and are compared with the result obtained by a linear chain model. In addition, the doping dependence is investigated in the absence of Coulomb interaction. It is shown that the oscillator strength of each carbon nanotube shows qualitatively the same doping dependence, but the fine structure is different due to it's own peculiar band structure. Some relations independent of the radius of the tube are derived, and a useful formula for determining the amount of doping is proposed.Comment: 4 pages, 4 figures, submitted to J. Phys. Soc. Jpn. at June 30, 200

Left ventricular non-compaction: clinical features and cardiovascular magnetic resonance imaging

Background: It is apparent that despite lack of family history, patients with the morphological characteristics of left ventricular non-compaction develop arrhythmias, thrombo-embolism and left ventricular dysfunction. METHODS: Forty two patients, aged 48.7 +/- 2.3 yrs (mean +/- SEM) underwent cardiovascular magnetic resonance (CMR) for the quantification of left ventricular volumes and extent of non-compacted (NC) myocardium. The latter was quantified using planimetry on the two-chamber long axis LV view (NC area). The patients included those referred specifically for CMR to investigate suspected cardiomyopathy, and as such is represents a selected group of patients. RESULTS: At presentation, 50% had dyspnoea, 19% chest pain, 14% palpitations and 5% stroke. Pulmonary embolism had occurred in 7% and brachial artery embolism in 2%. The ECG was abnormal in 81% and atrial fibrillation occurred in 29%. Transthoracic echocardiograms showed features of NC in only 10%. On CMR, patients who presented with dyspnoea had greater left ventricular volumes (both p < 0.0001) and a lower left ventricular ejection fraction (LVEF) (p < 0.0001) than age-matched, healthy controls. In patients without dyspnoea (n = 21), NC area correlated positively with end-diastolic volume (r = 0.52, p = 0.0184) and end-systolic volume (r = 0.56, p = 0.0095), and negatively with EF (r = -0.72, p = 0.0001). CONCLUSION: Left ventricular non-compaction is associated with dysrrhythmias, thromboembolic events, chest pain and LV dysfunction. The inverse correlation between NC area and EF suggests that NC contributes to left ventricular dysfunction

CRISPR-Cas9 screens in human cells and primary neurons identify modifiers of C9ORF72 dipeptide-repeat-protein toxicity.

Hexanucleotide-repeat expansions in the C9ORF72 gene are the most common cause of amyotrophic lateral sclerosis and frontotemporal dementia (c9ALS/FTD). The nucleotide-repeat expansions are translated into dipeptide-repeat (DPR) proteins, which are aggregation prone and may contribute to neurodegeneration. We used the CRISPR-Cas9 system to perform genome-wide gene-knockout screens for suppressors and enhancers of C9ORF72 DPR toxicity in human cells. We validated hits by performing secondary CRISPR-Cas9 screens in primary mouse neurons. We uncovered potent modifiers of DPR toxicity whose gene products function in nucleocytoplasmic transport, the endoplasmic reticulum (ER), proteasome, RNA-processing pathways, and chromatin modification. One modifier, TMX2, modulated the ER-stress signature elicited by C9ORF72 DPRs in neurons and improved survival of human induced motor neurons from patients with C9ORF72 ALS. Together, our results demonstrate the promise of CRISPR-Cas9 screens in defining mechanisms of neurodegenerative diseases

Social Participation and Disaster Risk Reduction Behaviors in Tsunami Prone Areas

This paper examines the relationships between social participation and disaster risk reduction actions. A survey of 557 households in tsunami prone areas in Phang Nga, Thailand was conducted following the 2012 Indian Ocean earthquakes. We use a multivariate probit model to jointly estimate the likelihood of undertaking three responses to earthquake and tsunami hazards (namely, (1) following disaster-related news closely, (2) preparing emergency kits and/or having a family emergency plan, and (3) having an intention to migrate) and community participation.We find that those who experienced losses from the 2004 tsunami are more likely to participate in community activities and respond to earthquake hazards. Compared to men, women are more likely to prepare emergency kits and/or have an emergency plan and have a greater intention to migrate. Living in a community with a higher proportion of women with tertiary education increases the probability of engaging in community activities and carrying out disaster risk reduction measures. Individuals who participate in village-based activities are 5.2% more likely to undertake all three risk reduction actions compared to those not engaging in community activities. This implies that encouraging participation in community activities can have positive externalities in disaster mitigation

Serum albumin levels and economic status in Japanese older adults

Background: Low serum albumin levels are associated with aging and medical conditions such as cancer, liver dysfunction, inflammation, and malnutrition and might be an independent predictor of long-term mortality in healthy older populations. We tested the hypothesis that economic status is associated with serum albumin levels and explained by nutritional and health status in Japanese older adults. Design: We performed a cross-sectional analysis using data from the Japan Gerontological Evaluation study (JAGES). The study participants were 6528 functionally independent residents (3189 men and 3339 women) aged ≥65 years living in four municipalities in Aichi prefecture. We used household income as an indicator of economic status. Multiple linear regression was used to compare serum albumin levels in relation to household income, which was classified as low, middle, and high. Additionally, mediation by nutritional and health-related factors was analyzed in multivariable models. Results: With the middle-income group as reference, participants with low incomes had a significantly lower serum albumin level, even after adjustment for sex, age, residential area, education, marital status, and household structure. The estimated mean difference was -0.17 g/L (95% confidence interval, -0.33 to -0.01 g/L). The relation between serum albumin level and low income became statistically insignificant when "body mass index", "consumption of meat or fish", "self-rated health", "presence of medical conditions", "hyperlipidemia", or "respiratory disease "was included in the model. Conclusion: Serum albumin levels were lower in Japanese older adults with low economic status. The decrease in albumin levels appears to be mediated by nutrition and health-related factors with low household incomes. Future studies are needed to reveal the existence of other pathways

Mechanisms and models of somatic cell reprogramming

Whitehead Institute for Biomedical Research (Jerome and Florence Brill Graduate Student Fellowship)National Institutes of Health (U.S.) (US NIH grant RO1-CA087869)National Institutes of Health (U.S.) (US NIH grant R37-CA084198)National Science Foundation (U.S.) (NSF Graduate Research Fellowship)National Institutes of Health (U.S.) ((NIH) Kirschstein National Research Service Award,1 F32 GM099153-01A1)Vertex Pharmaceuticals Incorporated (Vertex Scholar

A combination of right ventricular hypertrabeculation/noncompaction and arrhythmogenic right ventricular cardiomyopathy: a syndrome?

A combination of ARVC and RV NVM/HVM, which is extremely rare, to our knowledge, is never reported. RV NVM/HVM could be the cause and consequence of ARVC, or RV NVM/HVM and ARVC could be a consequence of a certain undetermined cause. It must be kept in mind, however, that the interaction of NVM/HVM and ARVC could be in part of pathophysiology mechanism of the combination even if as a consequence of an underlying genetic factor

Serum uric acid distribution according to SLC22A12 W258X genotype in a cross-sectional study of a general Japanese population

<p>Abstract</p> <p>Background</p> <p>Although <it>SLC22A12 258X </it>allele was found among those with hypouricemia, it was unknown that serum uric acid distribution among those with <it>SLC22A12 258X </it>allele. This study examined serum uric acid (SUA) distribution according to <it>SLC22A12 </it>W258X genotype in a general Japanese population.</p> <p>Methods</p> <p>Subjects were 5,023 health checkup examinees (3,413 males and 1,610 females) aged 35 to 69 years with creatinine < 2.0 mg/dL, who were participants of a cohort study belonging to the Japan Multi-Institutional Collaborative Cohort Study (J-MICC Study). <it>SLC22A12 </it>W258X was genotyped with a polymerase chain reaction with confronting two-pair primers.</p> <p>Results</p> <p>The genotype frequency was 4,793 for <it>WW</it>, 225 for <it>WX</it>, and 5 for <it>XX</it>, which was in Hardy-Weinberg equilibrium (p = 0.164) with <it>X </it>allele 0.023 (95% confidence interval [0.021-0.027]). Mean (range) SUA was 6.2 (2.1-11.4) mg/dL for <it>WW</it>, 3.9 (0.8-7.8) mg/dL for <it>WX</it>, and 0.8 (0.7-0.9) mg/dL for <it>XX </it>among males, and 4.5 (1.9-8.9) mg/dL, 3.3 (2.0-6.5) mg/dL, and 0.60 (0.5-0.7) mg/dL among females, respectively. Six individuals with SUA less than 1.0 mg/dL included two males with <it>XX </it>genotype, one male with <it>WX </it>genotype, and three females with <it>XX </it>genotype. Subjects with <it>WX </it>genotype were 14 (77.8%) of 18 males with a SUA of 1.0-2.9 mg/dL, and 28 (34.6%) of 81 females with the same range of SUA. The corresponding values were 131 (25.1%) of 522 males and 37 (3.5%) of 1,073 females for SUA 3.0-4.9 mg/dL, and 8 (0.4%) of 2,069 males and 5 (1.1%) of 429 females for SUA 5.0-6.9 mg/dL. The <it>X </it>allele effect for SUA less than 3 mg/dL was significantly (p < 0.001) higher in males (OR = 102.5, [33.9-309.8]) than in females (OR = 25.6 [14.4-45.3]).</p> <p>Conclusions</p> <p>Although <it>SLC22A12 </it>W258X was a determining genetic factor on SUA, SUA of those with <it>WX </it>genotype distributed widely from 0.8 mg/dL to 7.8 mg/dL. It indicated that other genetic traits and/or lifestyle affected SUA of those with <it>WX </it>genotype, as well as those with <it>WW </it>genotype.</p