Heterogeneous distribution of Culex pipiens, Culex quinquefasciatus and their hybrids along the urbanisation gradient

The mosquitoes of the Culex pipiens complex, hereafter referred to as the Pipiens Assemblage, are vectors of arbovirus of worldwide concern including West Nile and St. Louis encephalitis. Given their distinct eco-physiology and vectorial capacity, accurate specimen identification and insight in the environmental drivers of their distribution are essential for the understanding of disease transmission patterns. Using a PCR-based identification protocol, we characterized the spatial distribution of Cx. pipiens, Cx. quinquefasciatus and their hybrids developing in used tyres located within the overlapping region in South America as a function of different estimators of the urbanisation gradient. Out of 84 samples collected from tyre piles of 20 sites, we identified 369 larvae which corresponded predominantly to Cx. quinquefasciatus (76.4% of immatures) all along the gradient but more frequent at the urban end. Cx. pipiens (21.4%) was more conspicuous at the low urbanised end but was also present in highly urbanised sites, whereas hybrids were collected in very low numbers (2.2%). The urbanisation estimator best associated with the heterogeneous occurrence of the Pipiens Assemblage members was the proportion of impervious surface 1km around each tyre pile, which explained 41.7% of the variability in the data, followed closely by the distance to the Capital City (38.3%). Cumulative annual precipitation, population number in a 1km radius around each pile and distance to the de la Plata River were significantly associated with the distribution of the Pipiens Assemblage at lower explanation percentages (20-23%). A thorough understanding of the ecological basis and environmental associations of the distribution of Pipiens Assemblage members will enable forecasting population trends in changing environments to develop effective control measures for mosquitoes and the diseases they transmit.

Momentum-Resolved View of Electron-Phonon Coupling in Multilayer WSe_{2}

We investigate the interactions of photoexcited carriers with lattice vibrations in thin films of the layered transition metal dichalcogenide (TMDC) WSe_{2}. Employing femtosecond electron diffraction with monocrystalline samples and first-principles density functional theory calculations, we obtain a momentum-resolved picture of the energy transfer from excited electrons to phonons. The measured momentum-dependent phonon population dynamics are compared to first-principles calculations of the phonon linewidth and can be rationalized in terms of electronic phase-space arguments. The relaxation of excited states in the conduction band is dominated by intervalley scattering between Σ valleys and the emission of zone boundary phonons. Transiently, the momentum-dependent electron-phonon coupling leads to a nonthermal phonon distribution, which, on longer time scales, relaxes to a thermal distribution via electron-phonon and phonon-phonon collisions. Our results constitute a basis for monitoring and predicting out of equilibrium electrical and thermal transport properties for nanoscale applications of TMDCs.

[Nasogastric rehydration for treating children with gastroenteritis]

INTRODUCTION

When oral rehydration is not feasible, enteral rehydration via the nasogastric route has been the ESPGHAN recommended method of rehydration since 2008, rather than intravenous rehydration (IVR), for children with acute gastroenteritis. However, these recommendations are rarely followed in France. Since 2011, in case of failure of oral rehydration, enteral rehydration has been used as a first-line therapy in the Children's Emergency Department at the Grenoble-Alpes University Hospital.

PURPOSE

The aims of the study were to compare the length of the hospital stay, the duration of initial rehydration, and the incidence of complications and failure with the use of enteral nasogastric versus intravenous rehydration.

METHODS

This study compared two cohorts of children (<3 years of age) with mild-to-moderate dehydration caused by acute gastroenteritis and failure of rehydration via the oral route. The first group (winter 2010-2011) was managed according to the previous protocol (intravenous rehydration). The second group (winter 2011-2012) was managed according the new protocol (nasogastric tube rehydration [NGR]). The rest of the gastroenteritis management was identical in both groups.

RESULTS

A total of 132 children were included, 65 were treated with nasogastric tube rehydration (NGR) and 67 with intravenous rehydration. There was a significant reduction in the duration of hospitalization in the post-emergency unit in the NGR group: 23.6h vs 40.1h (P<0.05). The duration of initial rehydration was also significantly reduced (10.5h vs 22.0h). There was no significant difference regarding serious adverse events. However, the NGR group presented more mild adverse events (22 vs 7, P<0.05) and more treatment failures (15.3% vs 3%, P=0.013).

CONCLUSION

Nasogastric rehydration reduces the duration of rehydration and the length of the hospital stay without increasing the incidence of serious adverse events for dehydrated children hospitalized for acute gastroenteritis.

Prevalence and Phylogenetic Analysis of Bartonella Species of Wild Carnivores and Their Fleas in Northwestern Mexico

The host-parasite-vector relationship of Bartonella spp. system in wild carnivores and their fleas from northwestern Mexico was investigated. Sixty-six carnivores belonging to eight species were sampled, and 285 fleas belonging to three species were collected during spring (April-May) and fall (October-November) seasons. We detected Bartonella species in 7 carnivores (10.6%) and 27 fleas (9.5%) through either blood culture or PCR. Of the 27 Bartonella-positive fleas, twenty-two were Pulex simulans, three were Pulex irritans and one was Echidnophaga gallinacea. The gltA gene and ITS region sequences alignment revealed six and eight genetic variants of Bartonella spp., respectively. These variants were clustered into Bartonella rochalimae, Bartonella vinsonii subsp. berkhoffii and another genotype, which likely represents a novel species of Bartonella spp. Although experimental infection studies are required to prove the vector role of P. simulans, our results suggest that this flea may play an important role in the Bartonella transmission. The results indicated possible host-specific relationships between Bartonella genotypes and the families of the carnivores, but further studies are needed to verify this finding. The presence of zoonotic species of Bartonella spp. in wild carnivores raises the issue of their potential risk for humans in fragmented ecosystems.

FOTROCAN Delphi consensus statement regarding the prevention and treatment of cancer-associated thrombosis in areas of uncertainty and low quality of evidence

INTRODUCTION

Decision-making in cancer-related venous thromboembolism (VTE) is often founded on scant lines of evidence and weak recommendations. The aim of this work is to evaluate the percentage of agreement surrounding a series of statements about complex, clinically relevant, and highly uncertain aspects to formulate explicit action guidelines.

MATERIALS AND METHODS

Opinions were based on a structured questionnaire with appropriate scores and were agreed upon using a Delphi method. Questions were selected based on a list of recommendations with low evidence from the Spanish Society of Oncology Clinical Guideline for Thrombosis. The questionnaire was completed in two iterations by a multidisciplinary panel of experts in thrombosis.

RESULTS

Of the 123 statements analyzed, the panel concurred on 22 (17%) and another 81 (65%) were agreed on by qualified majority, including important aspects of long-term and prolonged anticoagulation, major bleeding and rethrombosis management, treatment in special situations, catheter-related thrombosis and thromboprophylaxis. Among them, the panelists agreed the incidental events should be equated to symptomatic ones, long-term and extended use of full-dose low-molecular weight heparin, and concluded that the Khorana score is not sensitive enough to uphold an effective thromboprophylaxis strategy.

CONCLUSION

Though the level of consensus varied depending on the scenario presented, overall, the iterative process achieved broad agreement as to the general treatment principles of cancer-associated VTE. Clinical validation of these statements in genuine practice conditions would be useful.

Diagnosis Accuracy of Transcutaneous Bilirubinometry in Very Preterm Newborns

BACKGROUND

Transcutaneous bilirubin (TcB) is a validated test for systematic screening of neonatal hyperbilirubinemia and monitoring term and near-term infants under phototherapy.

OBJECTIVES

To evaluate TcB diagnostic accuracy for very preterm neonates.

METHODS

Total serum bilirubin (TSB) and TcB measurements were performed prospectively in a multicenter sample of newborns <30 weeks of gestational age (GA). TcB sensitivity, specificity, predictive values, and likelihood ratios for the detection of neonates requiring phototherapy were calculated over the first 15 days of life, with or without phototherapy, with the expectation of achieving a detection rate of hyperbilirubinemia of over 95%. The potential influence of neonatal characteristics on the discordance between TcB and TSB in very preterm newborns was analyzed using multivariate multilevel logistic regression analyses.

RESULTS

Altogether, 481 measurements were analyzed in 167 preterm patients. Mean GA was 27.6 ± 1.6 weeks. The rates of newborns requiring phototherapy were 52% in the first 3 days, 16% from the 4th to the 7th day, and 2% during the second week. Diagnostic performance was similar among babies with or without phototherapy. TcB sensitivity decreased over time from 100% (93.9-100.0) to 50% (1.3-98.7). Specificity showed an inverse evolution from 14.8% (7.0-26.2) to 80.7% (72.2-89.2). The best performance was that of negative predictive values which varied from 95.5 to 100.0. False negatives were rare throughout the study (0.8% of measurements). In a multivariate analysis, the only factor significantly influencing discordance between TcB and TSB was postnatal age. We did not find any impact of GA and skin color.

CONCLUSION

Among very preterm babies, TcB measurements might be useful for screening for neonatal jaundice in the first 2 weeks of life. In case of a TcB value below the phototherapy threshold, invasive TSB quantification could be unnecessary, with potential avoidance of blood drawing.

Generation and Evolution of Spin-, Valley-, and Layer-Polarized Excited Carriers in Inversion-Symmetric WSe_{2}

We report the spin-selective optical excitation of carriers in inversion-symmetric bulk samples of the transition metal dichalcogenide (TMDC) WSe_{2}. Employing time- and angle-resolved photoelectron spectroscopy (trARPES) and complementary time-dependent density functional theory (TDDFT), we observe spin-, valley-, and layer-polarized excited state populations upon excitation with circularly polarized pump pulses, followed by ultrafast (<100  fs) scattering of carriers towards the global minimum of the conduction band. TDDFT reveals the character of the conduction band, into which electrons are initially excited, to be two-dimensional and localized within individual layers, whereas at the minimum of the conduction band, states have a three-dimensional character, facilitating interlayer charge transfer. These results establish the optical control of coupled spin-, valley-, and layer-polarized states in centrosymmetric materials with locally broken symmetries and suggest the suitability of TMDC multilayer and heterostructure materials for valleytronic and spintronic device concepts.

Brain responses to uncertainty about upcoming rectal discomfort in quiescent Crohn's disease - a fMRI study

BACKGROUND

Patients with Crohn's disease (CD) in remission are exposed to chronic psychological distress, due to the constant risk of relapse. This permanent situation of anticipation and uncertainty can lead to anxiety, which may, in turn, trigger relapse. We aimed to investigate the effects of uncertainty on behavioral and brain responses to anticipation of visceral discomfort in quiescent CD patients.

METHODS

Barostat-controlled rectal distensions were preceded by cued uncertain or certain anticipation in nine CD patients and nine matched healthy volunteers. Brain responses obtained before distension across the different anticipation conditions in regions of interest (ROI) involved in (anticipation of) pain were measured using functional magnetic resonance imaging and compared between CD and controls. The association between anxiety-related psychological variables and cerebral anticipatory activity was tested.

KEY RESULTS

During uncertainty, CD patients had significantly stronger activations than controls in the cingulate cortex, insula, amygdala, and thalamus with trends in the hippocampus, prefrontal, and secondary somatosensory cortex. In patients, brain responses to uncertainty in the majority of ROI correlated positively with gastrointestinal symptom-specific anxiety, trait-anxiety, and intolerance of uncertainty.

CONCLUSIONS & INFERENCES

In a context of uncertainty regarding occurrence of uncomfortable visceral sensations, CD is associated with excessive reactivity in brain regions known to be involved in sensory, cognitive and emotional aspects of pain processing and modulation, and threat appraisal. Our findings contribute to a better understanding of the role of emotional and cognitive processes in CD. This may, in turn, lead to the development of new (psycho)therapeutic approaches for management of symptoms and related anxiety.

[Collagenous gastritis and colitis in a 10-year-old girl]

There are few data in the literature on microscopic gastritis and colitis in the pediatric population. The diagnosis is often made after the occurrence of complications. We report the case of a 10.5 year-old girl for whom the diagnosis was made several years after the initial symptoms. Test for infections, inflammation, and auto-immunity yielded normal results. Upper endoscopy and colonoscopy revealed an abnormal mucosa. However, histology showed microscopic inflammation and fibrotic lesions in the lamina propria, and a thick subepithelial collagenous band. This led to the diagnosis of collagenous gastritis and colitis. Budesonide treatment resulted in the cessation of diarrhea and significant weight gain. Treatment by oral budesonide indeed seems to be highly effective but relapses are frequent when the treatment is stopped. This case shows the importance of being vigilant regarding transit disorders with impact on growth kinetics. Upper endoscopy and colonoscopy need to be carried out when children have organic diarrhea with normal blood tests.

Characterization and isolation of immature neurons of the adult mouse piriform cortex

Physiological studies indicate that the piriform or primary olfactory cortex of adult mammals exhibits a high degree of synaptic plasticity. Interestingly, a subpopulation of cells in the layer II of the adult piriform cortex expresses neurodevelopmental markers, such as the polysialylated form of neural cell adhesion molecule (PSA-NCAM) or doublecortin (DCX). This study analyzes the nature, origin, and potential function of these poorly understood cells in mice. As previously described in rats, most of the PSA-NCAM expressing cells in layer II could be morphologically classified as tangled cells and only a small proportion of larger cells could be considered semilunar-pyramidal transitional neurons. Most were also immunoreactive for DCX, confirming their immature nature. In agreement with this, detection of PSA-NCAM combined with that of different cell lineage-specific antigens revealed that most PSA-NCAM positive cells did not co-express markers of glial cells or mature neurons. Their time of origin was evaluated by birthdating experiments with halogenated nucleosides performed at different developmental stages and in adulthood. We found that virtually all cells in this paleocortical region, including PSA-NCAM-positive cells, are born during fetal development. In addition, proliferation analyses in adult mice revealed that very few cells were cycling in layer II of the piriform cortex and that none of them was PSA-NCAM-positive. Moreover, we have established conditions to isolate and culture these immature neurons in the adult piriform cortex layer II. We find that although they can survive under certain conditions, they do not proliferate in vitro either. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 748-763, 2016.

Uncertainty in anticipation of uncomfortable rectal distension is modulated by the autonomic nervous system--a fMRI study in healthy volunteers

The human brain responds both before and during the application of aversive stimuli. Anticipation allows the organism to prepare its nociceptive system to respond adequately to the subsequent stimulus. The context in which an uncomfortable stimulus is experienced may also influence neural processing. Uncertainty of occurrence, timing and intensity of an aversive event may lead to increased anticipatory anxiety, fear, physiological arousal and sensory perception. We aimed to identify, in healthy volunteers, the effects of uncertainty in the anticipation of uncomfortable rectal distension, and the impact of the autonomic nervous system (ANS) activity and anxiety-related psychological variables on neural mechanisms of anticipation of rectal distension using fMRI. Barostat-controlled uncomfortable rectal distensions were preceded by cued uncertain or certain anticipation in 15 healthy volunteers in a fMRI protocol at 3T. Electrocardiographic data were concurrently registered by MR scanner. The low frequency (LF)-component of the heart rate variability (HRV) time-series was extracted and inserted as a regressor in the fMRI model ('LF-HRV model'). The impact of ANS activity was analyzed by comparing the fMRI signal in the 'standard model' and in the 'LF-HRV model' across the different anticipation and distension conditions. The scores of the psychological questionnaires and the rating of perceived anticipatory anxiety were included as covariates in the fMRI data analysis. Our experiments led to the following key findings: 1) the subgenual anterior cingulate cortex (sgACC) is the only activation site that relates to uncertainty in healthy volunteers and is directly correlated to individual questionnaire score for pain-related anxiety; 2) uncertain anticipation of rectal distension involved several relevant brain regions, namely activation of sgACC and medial prefrontal cortex and deactivation of amygdala, insula, thalamus, secondary somatosensory cortex, supplementary motor area and cerebellum; 3) most of the brain activity during anticipation, but not distension, is associated with activity of the central autonomic network. This approach could be applied to study the ANS impact on brain activity in various pathological conditions, namely in patients with chronic digestive conditions characterized by visceral discomfort and ANS imbalance such as irritable bowel syndrome or inflammatory bowel diseases.