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Found 37684 matches. Displaying 6531-6540
Vincent QB, Ardant MF, Adeye A, Goundote A, Saint-Andre JP, Cottin J, Kempf M, Agossadou D, Johnson C, Abel L, Marsollier L, Chauty A, Alcais A
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Clinical epidemiology of laboratory-confirmed Buruli ulcer in Benin: a cohort study

LANCET GLOBAL HEALTH 2014 JUL; 2(7):E422-E430
Background Buruli ulcer, caused by Mycobacterium ulcerans, was identified as a neglected emerging infectious disease by WHO in 1998. Although Buruli ulcer is the third most common mycobacterial disease worldwide, understanding of the disease is incomplete. We analysed a large cohort of laboratory-confirmed cases of Buruli ulcer from Pob, Benin, to provide a comprehensive description of the clinical presentation of the disease, its variation with age and sex, and its effect on the occurrence of permanent functional sequelae. Methods Between Jan 1, 2005, and Dec 31, 2011, we prospectively collected clinical and laboratory data from all patients with Buruli ulcer diagnosed at the Centre de Depistage et de Traitement de l'Ulcere de Buruli in Pob, Benin. We followed up patients to assess the frequency of permanent functional sequelae. All analyses were done on cases that were laboratory confirmed. Findings 1227 cases of laboratory-confirmed Buruli ulcer were included in the analysis. Typically, patients with Buruli ulcer were children (median age at diagnosis 12 years) presenting with a unique (1172 [96%]) large (>= 15 cm, 444 [36%]) ulcerative (805 [66%]) lesion of the lower limb (733 [60%]). Atypical clinical presentation of Buruli ulcer included Buruli ulcer osteomyelitis with no identifiable present or past Buruli ulcer skin lesions, which was recorded in at least 14 patients. The sex ratio of Buruli ulcer widely varied with age, with male patients accounting for 57% (n= 427) of patients aged 15 years and younger, but only 33% (n=158) of those older than 15 years (odds ratio [OR] 2.59, 95% CI 2.04-3.30). Clinical presentation of Buruli ulcer was significantly dependent on age and sex. 54 (9%) male patients had Buruli ulcer osteomyelitis, whereas only 28 (4%) of female patients did (OR 2.21, 95% CI 1.39-3.59). 1 year after treatment, 229 (22% of 1043 with follow-up information) patients presented with permanent functional sequelae. Presentation with oedema, osteomyelitis, or large (>= 15 cm in diameter), or multifocal lesions was significantly associated with occurrence of permanent functional sequelae (OR 7.64, 95% CI 5.29-11.31) and operationally defines severe Buruli ulcer. Interpretation Our findings have important clinical implications for daily practice, including enhanced surveillance for early detection of osteomyelitis in boys; systematic search for M ulcerans in osteomyelitis cases of non-specific aspect in areas endemic for Buruli ulcer; and specific disability prevention for patients presenting with osteomyelitis, oedema, or multifocal or large lesions. Our findings also suggest a crucial underestimation of the burden of Buruli ulcer in Africa and raise key questions about the contribution of environmental and physiopathological factors to the recorded heterogeneity of the clinical presentation of Buruli ulcer.
Li J, Duarte T, Kocabas A, Works M, McConnell SK, Hynes MA
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Evidence for topographic guidance of dopaminergic axons by differential Netrin-1 expression in the striatum

MOLECULAR AND CELLULAR NEUROSCIENCE 2014 JUL; 61(?):85-96
There are two main subgroups of midbrain dopaminergic (DA) neurons: the more medially located ventral tegmental area (VTA) DA neurons, which have axons that innervate the ventral-lateral (VL) striatum, and the more laterally located substantia nigra (SN) DA neurons, which preferentially degenerate in Parkinson's disease (PD) and have axons that project to the dorsal-medial (DM) striatum. DA axonal projections in the striatum are not discretely localized and they arborize widely, however they do not stray from one zone to the other so that VTA axons remain in the VL zone and SN axons in the DM zone. Here we provide evidence that Netrin-1 acts in a novel fashion to topographically pattern midbrain DA axons into these two striatal zones by means of a gradient of Netrin-1 in the striatum and by differential attraction of the axons to Netrin-1. Midbrain DA neurons are attracted to the striatum in culture and this attraction is blocked by an anti-DCC (Netrin receptor) antibody. Mechanistically, outgrowth of both VTA and SN DA axons is stimulated by Netrin-1, but the two populations of DA axons respond optimally to overlapping but distinct concentrations of Netrin-1, with SN axons preferring lower concentrations and VTA axons preferring higher concentrations. In vivo this differential preference is closely mirrored by differences in Netrin-1 expression in their respective striatal target fields. In vivo in mice lacking Netrin-1, DA axons that reach the striatum fail to segregate into two terminal zones and to fully innervate the striatum. Our results reveal novel actions for Netrin-1 and provide evidence for a mechanism through which DA axons can selectively innervate one of two terminal zones in the striatum but have free reign to arborize widely within a terminal zone. (C) 2014 Elsevier Inc. All rights reserved.
Litvin Y, Cataldo G, Pfaff DW, Kow LM
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Estradiol regulates responsiveness of the dorsal premammillary nucleus of the hypothalamus and affects fear- and anxiety-like behaviors in female rats

EUROPEAN JOURNAL OF NEUROSCIENCE 2014 JUL; 40(2):2344-2351
Research suggests a causal link between estrogens and mood. Here, we began by examining the effects of estradiol (E-2) on rat innate and conditioned defensive behaviors in response to cat odor. Second, we utilized whole-cell patch clamp electrophysiological techniques to assess noradrenergic effects on neurons within the dorsal premammillary nucleus of the hypothalamus (PMd), a nucleus implicated in fear reactivity, and their regulation by E-2. Our results show that E-2 increased general arousal and modified innate defensive reactivity to cat odor. When ovariectomized females treated with E-2 as opposed to oil were exposed to cat odor, they showed elevations in risk assessment and reductions in freezing, indicating a shift from passive to active coping. In addition, animals previously exposed to cat odor showed clear cue + context conditioning 24 h later. However, although E-2 persisted in its effects on general arousal in the conditioning task, its effects on fear disappeared. In the patch clamp experiments noradrenergic compounds that typically induce fear clearly excited PMd neurons, producing depolarizations and action potentials. E-2 treatment shifted some excitatory effects of noradrenergic agonists to inhibitory, possibly by differentially affecting a-and beta-adrenoreceptors. In summary, our results implicate E-2 in general arousal and fear reactivity, and suggest these may be governed by changes in noradrenergic responsivity in the PMd. These effects of E-2 may have ethological relevance, serving to promote mate seeking even in contexts of ambiguous threat and shed light on the involvement of estrogen in mood and its associated disorders.
Farazi TA, Leonhardt CS, Mukherjee N, Mihailovic A, Li S, Max KEA, Meyer C, Yamaji M, Cekan P, Jacobs NC, Gerstberger S, Bognanni C, Larsson E, Ohler U, Tuschl T
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Identification of the RNA recognition element of the RBPMS family of RNA-binding proteins and their transcriptome-wide mRNA targets

RNA-A PUBLICATION OF THE RNA SOCIETY 2014 JUL; 20(7):1090-1102
Recent studies implicated the RNA-binding protein with multiple splicing (RBPMS) family of proteins in oocyte, retinal ganglion cell, heart, and gastrointestinal smooth muscle development. These RNA-binding proteins contain a single RNA recognition motif (RRM), and their targets and molecular function have not yet been identified. We defined transcriptome-wide RNA targets using photoactivatable-ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) in HEK293 cells, revealing exonic mature and intronic pre-mRNA binding sites, in agreement with the nuclear and cytoplasmic localization of the proteins. Computational and biochemical approaches defined the RNA recognition element (RRE) as a tandem CAC trinucleotide motif separated by a variable spacer region. Similar to other mRNA-binding proteins, RBPMS family of proteins relocalized to cytoplasmic stress granules under oxidative stress conditions suggestive of a support function for mRNA localization in large and/or multinucleated cells where it is preferentially expressed.
Rosa A, Papaioannou MD, Krzyspiak JE, Brivanlou AH
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miR-373 is regulated by TGF beta signaling and promotes mesendoderm differentiation in human Embryonic Stem Cells

DEVELOPMENTAL BIOLOGY 2014 JUL 1; 391(1):81-88
MicroRNAs (miRNAs) belonging to the evolutionary conserved miR-302 family play important functions in Embryonic Stem Cells (ESCs). The expression of some members, such as the human miR-302 and mouse miR-290 clusters, is regulated by ESC core transcription factors. However, whether miRNAs act downstream of signaling pathways involved in human ESC pluripotency remains unknown. The maintenance of pluripotency in hESCs is under the control of the TGF beta pathway. Here, we show that inhibition of the Activin/Nodal branch of this pathway affects the expression of a subset of miRNAs in hESCs. Among them, we found miR-373, a member of the miR-302 family. Proper levels of miR-373 are crucial for the maintenance of hESC pluripotency, since its overexpression leads to differentiation towards the mesendodermal lineage. Among miR-373 predicted targets, involved in TGF beta signaling, we validated the Nodal inhibitor Lefty. Our work suggests a crucial role for the interplay between miRNAs and signaling pathways in ESCs. (C) 2014 Elsevier Inc. All rights reserved.
Gardete S, Tomasz A
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Mechanisms of vancomycin resistance in Staphylococcus aureus

JOURNAL OF CLINICAL INVESTIGATION 2014 JUL; 124(7):2836-2840
Vancomycin is a glycopeptide antibiotic used for the treatment of Gram-positive bacterial infections. Traditionally, it has been used as a drug of last resort; however, clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) strains with decreased susceptibility to vancomycin (vancomycin intermediate-resistant S. aureus [VISA]) and more recently with high-level vancomycin resistance (vancomycin-resistant S. aureus [VRSA]) have been described in the clinical literature. The rare VRSA strains carry transposon Tn1546, acquired from vancomycin-resistant Enterococcus faecalis, which is known to alter cell wall structure and metabolism, but the resistance mechanisms in VISA isolates are less well defmed. Herein, we review selected mechanistic aspects of resistance in VISA and summarize biochemical studies on cell wall synthesis in a VRSA strain. Finally, we recapitulate a model that integrates common mechanistic features of VRSA and VISA strains and is consistent with the mode of action of vancomycin.
Spellicy CJ, Harding MJ, Hamon SC, Mahoney JJ, Reyes JA, Kosten TR, Newton TF, De La Garza R, Nielsen DA
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A variant in ANKK1 modulates acute subjective effects of cocaine: a preliminary study

GENES BRAIN AND BEHAVIOR 2014 JUL; 13(6):559-564
This study aimed to evaluate whether functional variants in the ankyrin repeat and kinase domain-containing 1 (ANKK1) gene and/or the dopamine receptor D2 (DRD2) gene modulate the subjective effects (reward or non-reward response to a stimulus) produced by cocaine administration. Cocaine-dependent participants (N = 47) were administered 40 mg of cocaine or placebo at time 0, and a subjective effects questionnaire (visual analog scale) was administered 15 min prior to cocaine administration, and at 5, 10, 15 and 20 min following administration. The influence of polymorphisms in the ANKK1 and DRD2 genes on subjective experience of cocaine in the laboratory was tested. Participants with a T allele of ANKK1 rs1800497 experienced greater subjective 'high' (P = 0.00006), 'any drug effect' (P = 0.0003) and 'like' (P = 0.0004) relative to the CC genotype group. Although the variant in the DRD2 gene was shown to be associated with subjective effects, linkage disequilibrium analysis revealed that this association was driven by the ANKK1 rs1800497 variant. A participant's ANKK1 genotype may identify individuals who are likely to experience greater positive subjective effects following cocaine exposure, including greater 'high' and 'like', and these individuals may have increased vulnerability to continue using cocaine or they may be at greater risk to relapse during periods of abstinence. However, these results are preliminary and replication is necessary to confirm these findings.
Gaschignard J, Levy C, Chrabieh M, Boisson B, Bost-Bru C, Dauger S, Dubos F, Durand P, Gaudelus J, Gendrel D, Le Guen CG, Grimprel E, Guyon G, Jeudy C, Jeziorski E, Leclerc F, Leger PL, Lesage F, Lorrot M, Pellier I, Pinquier D, de Pontual L, Sachs P, Thomas C, Tissieres P, Valla FV, Desprez P, Fremeaux-Bacchi V, Varon E, Bossuyt X, Cohen R, Abel L, Casanova JL, Puel A, Picard C
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Invasive Pneumococcal Disease in Children Can Reveal a Primary Immunodeficiency

CLINICAL INFECTIOUS DISEASES 2014 JUL 15; 59(2):244-251
Background. About 10% of pediatric patients with invasive pneumococcal disease (IPD) die from the disease. Some primary immunodeficiencies (PIDs) are known to confer predisposition to IPD. However, a systematic search for these PIDs has never been carried out in children presenting with IPD. Methods. We prospectively identified pediatric cases of IPD requiring hospitalization between 2005 and 2011 in 28 pediatric wards throughout France. IPD was defined as a positive pneumococcal culture, polymerase chain reaction result, and/or soluble antigen detection at a normally sterile site. The immunological assessment included abdominal ultrasound, whole-blood counts and smears, determinations of plasma immunoglobulin and complement levels, and the evaluation of proinflammatory cytokines. Results. We included 163 children with IPD (male-to-female ratio, 1.3; median age, 13 months). Seventeen children had recurrent IPD. Meningitis was the most frequent type of infection (87%); other infections included pleuropneumonitis, isolated bloodstream infection, osteomyelitis, endocarditis, and mastoiditis. One patient with recurrent meningitis had a congenital cerebrospinal fluid fistula. The results of immunological explorations were abnormal in 26 children (16%), and a PID was identified in 17 patients (10%), including 1 case of MyD88 deficiency, 3 of complement fraction C2 or C3 deficiencies, 1 of isolated congenital asplenia, and 2 of Bruton disease (X-linked agammaglobulinemia). The proportion of PIDs was much higher in children aged >2 years than in younger children (26% vs 3%; P < .001). Conclusions. Children with IPD should undergo immunological investigations, particularly those aged >2 years, as PIDs may be discovered in up to 26% of cases.
Meredith LS, Eisenman DP, Green BL, Kaltman S, Wong EC, Han B, Cassells A, Tobin JN
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Design of the Violence and Stress Assessment (ViStA) study: A randomized controlled trial of care management for PTSD among predominantly Latino patients in safety net health centers

CONTEMPORARY CLINICAL TRIALS 2014 JUL; 38(2):163-172
Posttraumatic stress disorder (PTSD) is a common problem in primary care. Although effective treatments are available, little is known about whether such treatments are effective within the context of Federally Qualified Health Centers (FQHCs) that serve as national "safety nets" for providing primary care for low income and underinsured patients. The Violence and Stress Assessment (ViStA) study is the first randomized controlled trial (RCT) to test the impact of a care management intervention for treating PTSD in FQHCs. To develop a PTSD management intervention appropriate for lower resource FQHCs and the predominantly Latino patients they serve, formative work was conducted through a collaborative effort between researchers and an FQHC practice-based research network. This article describes how FQHC stakeholders were convened to review, assess, and prioritize evidence-based strategies for addressing patient, clinician, and system-level barriers to care. This multi-component care management intervention incorporates diagnosis with feedback, patient education and activation; navigation and linkage to community resources; clinician education and medication guidance; and structured cross-disciplinary communication and continuity of care, all facilitated by care managers with FQHC experience. We also describe the evaluation design of this five-year RCT and the characteristics of the 404 English or Spanish speaking patients enrolled in the study and randomized to either the intervention or to usual care. Patients are assessed at baseline, six months, and 12 months to examine intervention effectiveness on PTSD, other mental health symptoms, health-related quality-of-life, health care service use; and perceived barriers to care and satisfaction with care. (C) 2014 Elsevier Inc. All rights reserved.
Reichenbach T, Hudspeth AJ
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The physics of hearing: fluid mechanics and the active process of the inner ear

REPORTS ON PROGRESS IN PHYSICS 2014 JUL; 77(7):? Article 076601
Most sounds of interest consist of complex, time-dependent admixtures of tones of diverse frequencies and variable amplitudes. To detect and process these signals, the ear employs a highly nonlinear, adaptive, real-time spectral analyzer: the cochlea. Sound excites vibration of the eardrum and the three miniscule bones of the middle ear, the last of which acts as a piston to initiate oscillatory pressure changes within the liquid-filled chambers of the cochlea. The basilar membrane, an elastic band spiraling along the cochlea between two of these chambers, responds to these pressures by conducting a largely independent traveling wave for each frequency component of the input. Because the basilar membrane is graded in mass and stiffness along its length, however, each traveling wave grows in magnitude and decreases in wavelength until it peaks at a specific, frequency-dependent position: low frequencies propagate to the cochlear apex, whereas high frequencies culminate at the base. The oscillations of the basilar membrane deflect hair bundles, the mechanically sensitive organelles of the ear's sensory receptors, the hair cells. As mechanically sensitive ion channels open and close, each hair cell responds with an electrical signal that is chemically transmitted to an afferent nerve fiber and thence into the brain. In addition to transducing mechanical inputs, hair cells amplify them by two means. Channel gating endows a hair bundle with negative stiffness, an instability that interacts with the motor protein myosin-1c to produce a mechanical amplifier and oscillator. Acting through the piezoelectric membrane protein prestin, electrical responses also cause outer hair cells to elongate and shorten, thus pumping energy into the basilar membrane's movements. The two forms of motility constitute an active process that amplifies mechanical inputs, sharpens frequency discrimination, and confers a compressive nonlinearity on responsiveness. These features arise because the active process operates near a Hopf bifurcation, the generic properties of which explain several key features of hearing. Moreover, when the gain of the active process rises sufficiently in ultraquiet circumstances, the system traverses the bifurcation and even a normal ear actually emits sound. The remarkable properties of hearing thus stem from the propagation of traveling waves on a nonlinear and excitable medium.