Simultaneous multi‐slice spin‐ and gradient‐echo dynamic susceptibility‐contrast perfusion‐weighted MRI of gliomas

Although combined spin‐ and gradient‐echo (SAGE) dynamic susceptibility‐contrast (DSC) MRI can provide perfusion quantification that is sensitive to both macrovessels and microvessels while correcting for T₁‐shortening effects, spatial coverage is often limited in order to maintain a high temporal resolution for DSC quantification. In this work, we combined a SAGE echo‐planar imaging (EPI) sequence with simultaneous multi‐slice (SMS) excitation and blipped controlled aliasing in parallel imaging (blipped CAIPI) at 3 T to achieve both high temporal resolution and whole brain coverage. Two protocols using this sequence with multi‐band (MB) acceleration factors of 2 and 3 were evaluated in 20 patients with treated gliomas to determine the optimal scan parameters for clinical use. ΔR₂*(t) and ΔR₂(t) curves were derived to calculate dynamic signal‐to‐noise ratio (dSNR), ΔR₂*‐ and ΔR₂‐based relative cerebral blood volume (rCBV), and mean vessel diameter (mVD) for each voxel. The resulting SAGE DSC images acquired using MB acceleration of 3 versus 2 appeared visually similar in terms of image distortion and contrast. The difference in the mean dSNR from normal‐appearing white matter (NAWM) and that in the mean dSNR between NAWM and normal‐appearing gray matter were not statistically significant between the two protocols. ΔR₂*‐ and ΔR₂‐rCBV maps and mVD maps provided unique contrast and spatial heterogeneity within tumors.     

Mutation analysis of tubulin beta 8 class VIII in infertile females with oocyte or embryonic defects

Variants of tubulin beta 8 class VIII (TUBB8) have been shown to be associated with female infertility characterized by oocyte or embryonic defects. To further investigate the mutational spectrum of TUBB8 and the prevalence of variants, we performed Sanger sequencing of TUBB8 on a total of 115 infertile females who had undergone repeated in vitro fertilization cycles with oocyte or embryonic defects and 200 healthy controls. A total of 31 variants which were absent from the controls were identified in 36 unrelated individuals, accounting for a large proportion of this cohort (31.3%). All of the variants including heterozygous/homozygous missense variants and a heterozygous frameshift insertion variant were at conserved sites and predicted to be deleterious. Besides, these variants had diverse phenotypic effects, including not only oocyte maturation arrest, fertilization failure, and early embryonic arrest, but also multi‐pronuclei (MPN) formation, which is a new phenotype associated with TUBB8 variants. Overall, this study reveals a large number of variants of the TUBB8 gene in infertile females with oocyte or embryonic defects. Our results not only broaden the mutational and phenotypic spectra of TUBB8 variants, but also further confirm the critical role of TUBB8 in oocyte maturation, fertilization, and early embryonic development.     

Poly(hydrosilane)s as Sources of Silyl Radicals and Their Use as Polymerization‐Initiating Structures

Poly(hydrosilane)s, [R(H)Si]_n [R = Ph, Si(CH₂)₃SiMe₂Th, cy‐Hex], are investigated as sources of silyl radicals. The Si–H bonds in these oligomers exhibit good to excellent hydrogen donating properties which ensure the formation of reactive silyl radicals. For free radical photopolymerization, the polymerization initiating properties of these structures are checked. These polymers are found to be advantageous to overcome the classical oxygen inhibition of the FRP process. Their ability in FRPCP is also evaluated for an epoxy monomer. The mechanisms are investigated through ESR and laser flash photolysis experiments.

     

Exposure and reorganization: The what and how of effective psychotherapy

Even though the effectiveness of psychotherapy is generally acknowledged, researchers are yet to agree on a plausible explanation for this effectiveness or on possible mechanisms of change that are activated by psychotherapy. To enhance developments in these areas some researchers have called for a focus on treatment principles rather than treatment techniques. In this respect, the technique of exposure is instructive. Despite its common use with anxiety disorders and the successful outcomes it produces, it has only recently been considered as a treatment for other disorders. By focussing on the underlying principles of exposure it is possible to consider exposure as a transdiagnostic component of successful psychotherapies. Understanding exposure from the perspective of Perceptual Control Theory (PCT) enables the identification of a functional, rather than a conceptual or statistical, mechanism of change. Functionally, exposure can be understood as an essential precursor to the internal reorganization that is necessary for the amelioration of psychological distress. PCT suggests a more considered and widespread use of exposure in psychotherapy as a way of improving both the efficiency and the effectiveness of the treatments offered.Despite the proliferation of psychotherapies in recent years there has not been a commensurate growth in our understanding of the effective ingredients of treatment. It seems unlikely that there are multitudes of different mechanisms and processes through which psychological distress is resolved and that each of these different psychotherapies utilises a distinct item from the collection. In fact, the spawning of hundreds of different psychotherapies is perhaps the most telling sign that there may still be much work to do before the important principles of treatment are described and fundamental mechanisms of change are identified. Could a technique as mundane as exposure hold the key to effective psychotherapy? For psychotherapy, is there just one road leading to Rome but a plethora of ways to travel that road?     

Interpersonal emotion regulation as a mechanism of social support in depression

Although social support is widely considered to be protective against depression, the mechanisms through which it acts on depressive psychopathology are not well known. This integrative review argues that emotion regulation serves as such a mechanism. First, the literature on the effects of social support on depression is reviewed, with an emphasis on open empirical questions regarding mechanisms linking support and depression. Then, the literature on emotion regulation is reviewed, highlighting its importance as a mechanism in the psychopathology of depression. Finally, potential interpersonal influences on depressive emotion regulation and dysregulation are suggested, drawing from theory and research on psychotherapy and on close relationships. The review suggests that emotion regulation is responsive to interpersonal influences, and that this responsiveness may account for the effects of social support on depression. Implications of an interpersonal perspective for basic and clinical research on depression, close relationships, and emotion regulation are discussed.     

子宫内膜异位症相关信号通路研究进展

子宫内膜异位症（EMs）作为妇科公认的疑难病,严重影响女性身心健康,因其病变多态性、侵袭性、广泛性,其发病机制目前尚无统一定论。相关信号通路的异常激活、多细胞因子的共同作用均会导致异位内膜细胞黏附、侵袭以及炎症的形成,目前丝裂原活化蛋白激酶（MAPKs）、Wnt/β-连环蛋白（β-catenin）、转化生长因子β（TGF-β）/Smad、核因子κB（NF-κB）、Ras同源基因/Rho相关螺旋卷曲蛋白激酶（Rho/ROCK）、Janus激酶2/转录活化因子3（JAK2/STAT3）等信号通路与EMs的发生、发展密切相关。现从以上6条通路阐述EMs的发病机制,为其寻找有效靶向药物治疗提供新的思路。     

Attentional gain and processing capacity limits predict the propensity to neglect unexpected visual stimuli

Exogenous allocation of attentional resources allows the visual system to encode and maintain representations of stimuli in visual working memory (VWM). However, limits in the processing capacity to allocate resources can prevent unexpected visual stimuli from gaining access to VWM and thereby to consciousness. Using a novel approach to create unbiased stimuli of increasing saliency, we investigated visual processing during a visual search task in individuals who show a high or low propensity to neglect unexpected stimuli. When propensity to inattention is high, ERP recordings show a diminished amplification concomitantly with a decrease in theta band power during the N1 latency, followed by a poor target enhancement during the N2 latency. Furthermore, a later modulation in the P3 latency was also found in individuals showing propensity to visual neglect, suggesting that more effort is required for conscious maintenance of visual information in VWM. Effects during early stages of processing (N80 and P1) were also observed suggesting that sensitivity to contrasts and medium‐to‐high spatial frequencies may be modulated by low‐level saliency (albeit no statistical group differences were found). In accordance with the Global Workplace Model, our data indicate that a lack of resources in low‐level processors and visual attention may be responsible for the failure to “ignite” a state of high‐level activity spread across several brain areas that is necessary for stimuli to access awareness. These findings may aid in the development of diagnostic tests and intervention to detect/reduce inattention propensity to visual neglect of unexpected stimuli.     

Illusory conjunctions in visual short‐term memory: Individual differences in corpus callosum connectivity and splitting attention between the two hemifields

Overloading the capacity of visual attention can result in mistakenly combining the various features of an object, that is, illusory conjunctions. We hypothesize that if the two hemispheres separately process visual information by splitting attention, connectivity of corpus callosum—a brain structure integrating the two hemispheres—would predict the degree of illusory conjunctions. In the current study, we assessed two types of illusory conjunctions using a memory‐scanning paradigm; the features were either presented across the two opposite hemifields or within the same hemifield. Four objects, each with two visual features, were briefly presented together followed by a probe‐recognition and a confidence rating for the recognition accuracy. MRI scans were also obtained. Results indicated that successful recollection during probe recognition was better for across hemifields conjunctions compared to within hemifield conjunctions, lending support to the bilateral advantage of the two hemispheres in visual short‐term memory. Age‐related differences regarding the underlying mechanisms of the bilateral advantage indicated greater reliance on recollection‐based processing in young and on familiarity‐based processing in old. Moreover, the integrity of the posterior corpus callosum was more predictive of opposite hemifield illusory conjunctions compared to within hemifield illusory conjunctions, even after controlling for age. That is, individuals with lesser posterior corpus callosum connectivity had better recognition for objects when their features were recombined from the opposite hemifields than from the same hemifield. This study is the first to investigate the role of the corpus callosum in splitting attention between versus within hemifields.     

In vivo observation of quadrupolar splitting in 39K magnetic resonance spectroscopy of human muscle tissue

The purpose of this work was to explore the origin of oscillations of the T^*₂ decay curve of ³⁹K observed in studies of ³⁹K magnetic resonance imaging of the human thigh. In addition to their magnetic dipole moment, spin‐³/₂ nuclei possess an electric quadrupole moment. Its interaction with non‐vanishing electrical field gradients leads to oscillations in the free induction decay and to splitting of the resonance. All measurements were performed on a 7T whole‐body MRI scanner (MAGNETOM 7T, Siemens AG, Erlangen, Germany) with customer‐built coils. According to the theory of quadrupolar splitting, a model with three Lorentzian‐shaped peaks is appropriate for ³⁹K NMR spectra of the thigh and calf. The frequency shifts of the satellites depend on the angle between the calf and the static magnetic field. When the leg is oriented parallel to the static magnetic field, the satellites are shifted by about 200 Hz. In the thigh, rank‐2 double quantum coherences arising from anisotropic quadrupolar interaction are observed by double‐quantum filtration with magic‐angle excitation. In addition to the spectra, an image of the thigh with a nominal resolution of (16 × 16 × 32) mm³ was acquired with this filtering technique in 1:17 h. From the line width of the resonances, ³⁹K transverse relaxation time constants T^*_{2, fast} = (0.51 ± 0.01) ms and T^*_{2, slow} = (6.21 ± 0.05) ms for the head were determined. In the thigh, the left and right satellite, both corresponding to the short component of the transverse relaxation time constant, take the following values: T^*_{2, fast} = (1.56 ± 0.03) ms and T^*_{2, fast} = (1.42 ± 0.03) ms. The centre line, which corresponds to the slow component, is T^*₂, _slow = (9.67 ± 0.04) ms. The acquisition time of the spectra was approximately 10 min. Our results agree well with a non‐vanishing electrical field gradient interacting with ³⁹K nuclei in the intracellular space of muscle tissue. Copyright © 2016 John Wiley & Sons, Ltd.