A balance of noncanonical Semaphorin signaling from the cerebrospinal fluid regulates apical cell dynamics during corticogenesis.

During corticogenesis, dynamic regulation of apical adhesion is fundamental to generate correct numbers and cell identities. While radial glial cells (RGCs) maintain basal and apical anchors, basal progenitors and neurons detach and settle at distal positions from the apical border. Whether diffusible signals delivered from the cerebrospinal fluid (CSF) contribute to the regulation of apical adhesion dynamics remains fully unknown.

X-linked partial corpus callosum agenesis with mild intellectual disability: identification of a novel L1CAM pathogenic variant.

Pathogenic variants in L1CAM, the gene encoding the L1 cell adhesion molecule, are responsible for a wide clinical spectrum including X-linked hydrocephalus with stenosis of the Sylvius aqueduct, MASA syndrome (mental retardation, aphasia, shuffling gait, adducted thumbs), and a form of spastic paraplegia (SPG1). A moderate phenotype with mild intellectual disability (ID) and X-linked partial corpus callosum agenesis (CCA) has only been related to L1CAM in one family. We report here a second family, including 5 patients with mild to moderate ID and partial CCA without signs usually associated with L1CAM pathogenic variations (such as hydrocephalus, pyramidal syndrome, thumb adductus, aphasia).

Understanding Bachelorhood in Poverty-stricken and High Sex Ratio Settings: An Exploratory Study in Rural Shaanxi, China.

Coupled with the social practice of female hypergamy, the male surplus within the never-married population means that today's Chinese marriage market is extremely tight in particular for men from a rural background and the least privileged socio-economic categories. Drawing on quantitative data from a survey conducted in 2014-2015, this article sheds light on the situation of single men who are past prime marriage age in three rural districts of Shaanxi particularly affected by this phenomenon. It compares single men's characteristics to those of their married counterparts and offers insights into the heterogeneity of single men with the aim of challenging some commonly accepted assumptions about bachelorhood in rural China.

A Spatiotemporal Sequence of Sensitization to Slits and Semaphorins Orchestrates Commissural Axon Navigation.

Accurate perception of guidance cues is crucial for cell and axon migration. During initial navigation in the spinal cord, commissural axons are kept insensitive to midline repellents. Upon midline crossing in the floor plate, they switch on responsiveness to Slit and Semaphorin repulsive signals and are thus propelled away and prevented from crossing back.

The dependence receptor TrkC regulates the number of sensory neurons during DRG development.

The development of the sensory nervous system is the result of fine-tuned waves of neurogenesis and apoptosis which control the appropriate number of precursors and newly generated neurons and orient them toward a specific lineage. Neurotrophins and their tyrosine-kinase receptors (RTK) orchestrate this process. They have long been in the scope of the neurotrophic theory which established that a neuron is committed to die unless a trophic factor generated by its target provides it with a survival signal.

Microenvironment-Driven Shift of Cohesion/Detachment Balance within Tumors Induces a Switch toward Metastasis in Neuroblastoma.

Neuroblastoma (NB) is a childhood cancer arising from sympatho-adrenal neural crest cells. Disseminated forms have high frequency of multiple tumoral foci whose etiology remains unknown; NB embryonic origin limits investigations in patients and current models. We developed an avian embryonic model driving human NB tumorigenesis in tissues homologous to patients.

Genetic specification of left-right asymmetry in the diaphragm muscles and their motor innervation.

The diaphragm muscle is essential for breathing in mammals. Its asymmetric elevation during contraction correlates with morphological features suggestive of inherent left-right (L/R) asymmetry. Whether this asymmetry is due to L versus R differences in the muscle or in the phrenic nerve activity is unknown.

Cerebrospinal fluid-derived Semaphorin3B orients neuroepithelial cell divisions in the apicobasal axis.

The spatial orientation of cell divisions is fundamental for tissue architecture and homeostasis. Here we analysed neuroepithelial progenitors in the developing mouse spinal cord to determine whether extracellular signals orient the mitotic spindle. We report that Semaphorin3B (Sema3B) released from the floor plate and the nascent choroid plexus in the cerebrospinal fluid (CSF) controls progenitor division orientation.

Marital sex among people living with HIV receiving antiretroviral treatment in northern Thailand.

Before the advent of effective antiretroviral treatment (ART), the sexuality of people living with HIV was mostly discussed in terms of risk. To assess the extent to which ART allows people living with HIV to regain a regular sexual life, we surveyed all HIV-infected people treated in four hospitals in Northern Thailand and a control group from the general population matched by sex, age and residence. Data included socio-demographic and health characteristics, frequency of sexual intercourse in the last month and condom use.

gdnf activates midline repulsion by Semaphorin3B via NCAM during commissural axon guidance.

The Neurotrophic factor gdnf plays diverse developmental roles, supporting survival and also acting as a chemoattractant for axon and cell migration. We report that in the developing spinal cord, a focal source of gdnf is present in the floor plate (FP) where commissural axons cross the midline. Gdnf has no direct guidance properties but switches on the responsiveness of crossing commissural growth cones to the midline repellent Semaphorin3B by suppressing calpain-mediated processing of the Sema3B signaling coreceptor Plexin-A1.

Motoneuronal Sema3C is essential for setting stereotyped motor tract positioning in limb-derived chemotropic semaphorins.

The wiring of neuronal circuits requires complex mechanisms to guide axon subsets to their specific target with high precision. To overcome the limited number of guidance cues, modulation of axon responsiveness is crucial for specifying accurate trajectories. We report here a novel mechanism by which ligand/receptor co-expression in neurons modulates the integration of other guidance cues by the growth cone.

Pathomechanistic characterization of two exonic L1CAM variants located in trans in an obligate carrier of X-linked hydrocephalus.

Mutations in the gene encoding the neural cell adhesion molecule L1CAM cause several neurological disorders collectively referred to as L1 syndrome. We report here a family case of X-linked hydrocephalus in which an obligate female carrier has two exonic L1CAM missense mutations in trans substituting amino acids in the first (p.W635C) or second (p.

Sexual risk-taking following relationship break-ups.

Background: Changes in sexual behaviour over time have resulted in more frequent relationship break-ups, which carry specific sexual health challenges that we aim to explore in this study.

Study Design: The data were drawn from the French sexual behaviour survey, comprising a random sample of 4,798 women and 4,045 men aged 18-44 years. Logistic regression models were used to describe the associations between recent relationship break-ups and reported sexually transmitted infections and abortions over the same period, and being tested positive for Chlamydia at the time of the survey.

Changes in sexual behaviours: from secular trends to public health policies.

Objective: To explore the relative contribution of secular trends and public health policies to changes in sexual behaviour.

Design: Three random probability surveys of the sexual behaviour of people aged 18-69 years were conducted in 1970, 1992 and 2006 in France.

Methods: Data of the 2006 survey (n = 12,364) were compared with those from two surveys carried out in 1970 (n = 2625) and 1992 (n = 20,055).

A midline switch of receptor processing regulates commissural axon guidance in vertebrates.

Commissural axon guidance requires complex modulations of growth cone sensitivity to midline-derived cues, but underlying mechanisms in vertebrates remain largely unknown. By using combinations of ex vivo and in vivo approaches, we uncovered a molecular pathway controlling the gain of response to a midline repellent, Semaphorin3B (Sema3B). First, we provide evidence that Semaphorin3B/Plexin-A1 signaling participates in the guidance of commissural projections at the vertebrate ventral midline.

A life course approach to patterns and trends in modern Latin American sexual behavior.

This article explores trends in sexual behavior in Latin America, envisaged from a life-course perspective, taking into account social differences. It is focused on three main issues: the timing of early sexual and reproductive events, sexual activity during adulthood, and measurement of homosexuality-bisexuality. It draws on general population data from nonspecific surveys, as surveys dealing specifically with sexual behavior are scarce in Latin American countries.

FAK-MAPK-dependent adhesion disassembly downstream of L1 contributes to semaphorin3A-induced collapse.

Axonal receptors for class 3 semaphorins (Sema3s) are heterocomplexes of neuropilins (Nrps) and Plexin-As signalling coreceptors. In the developing cerebral cortex, the Ig superfamily cell adhesion molecule L1 associates with Nrp1. Intriguingly, the genetic removal of L1 blocks axon responses of cortical neurons to Sema3A in vitro despite the expression of Plexin-As in the cortex, suggesting either that L1 substitutes for Plexin-As or that L1 and Plexin-A are both required and mediate distinct roles.

Semaphorin and neuropilin co-expression in motoneurons sets axon sensitivity to environmental semaphorin sources during motor axon pathfinding.

Class III semaphorins (SemaIIIs) are intercellular cues secreted by surrounding tissues to guide migrating cells and axons in the developing organism. This chemotropic activity is crucial for the formation of nerves and vasculature. Intriguingly, SemaIIIs are also synthesized by neurons during axon pathfinding, but their function as intrinsic cues remains unknown.

HIV prevalence, AIDS knowledge, and condom use among female sex workers in Santiago, Chile.

This paper describes HIV seroprevalence, knowledge of HIV transmission, and condom use among female sex workers (FSW) attending five specialized sexually transmitted disease (STD) clinics in Santiago, Chile. A short questionnaire with socio-demographic, AIDS knowledge, and condom-use variables was administered to 626 FSW. HIV seroprevalence was estimated with a blood test sent to the Chilean Public Health Institute.

New phenotype associated with an Arg116Cys mutation in the CRYAA gene: nuclear cataract, iris coloboma, and microphthalmia.

Objective: To describe a new phenotype with an arginine-to-cysteine mutation at position 116 (Arg116Cys) in the CRYAA gene.

Methods: We investigated a 4-generation French family with autosomal dominant cataract and performed a genetic linkage analysis using microsatellite DNA markers encompassing 15 known cataract loci. Exons 1, 2, and 3 and flanking intronic sequences of the CRYAA gene were amplified and analyzed using direct sequencing.

Dual functional activity of semaphorin 3B is required for positioning the anterior commissure.

Chemorepulsion by semaphorins plays a critical role during the development of neuronal projections. Although semaphorin-induced chemoattraction has been reported in vitro, the contribution of this activity to axon pathfinding is still unclear. Using genetic and culture models, we provide evidence that both attraction and repulsion by Sema3B, a secreted semaphorin, are critical for the positioning of a major brain commissural projection, the anterior commissure (AC).