253 research outputs found
PALB2 self-interaction controls homologous recombination.
PALB2 is essential for BRCA2 anchorage to nuclear structures and for homologous recombinational repair of DNA double-strand breaks. Here, we report that the N-terminal coiled-coil motif of PALB2 regulates its self-association and homologous recombination. Monomeric PALB2 shows higher efficiency to bind DNA and promotes RAD51 filament formation with or without the inhibitory effect of Replication Protein A. Moreover, overexpression of the PALB2 coiled-coil domain severely affects RAD51 loading to DNA damage sites suggesting a competition between PALB2 self-interaction and PALB2-BRCA1 interaction. In the presence of DNA damage, the switch between PALB2-PALB2 and PALB2-BRCA1 interactions allows the activation of HR. Controlling HR via PALB2 self-interactions could be important to prevent aberrant recombination in normal conditions and activate DNA repair when required
Les cadres de lâencadrement : la gouvernance intermĂ©diaire des systĂšmes Ă©ducatifs en question
La notion de « cadre » est de dĂ©veloppement rĂ©cent dans les organisations publiques, non pas que la hiĂ©rarchie des rĂŽles et des statuts en ait Ă©tĂ© absente, loin de lĂ , mais parce que le fonctionnement bureaucratique qui imprĂšgne leur tradition sâaccommodait mal de lâexistence dâune forme de responsabilitĂ© associant engagement dans lâaction collective et autonomie dâaction. Ce sont les dĂ©nonciations et les dĂ©fis auxquels lâadministration de lâaction publique a eu Ă rĂ©pondre au tournant des ann..
Les cadres de lâencadrement : la gouvernance intermĂ©diaire des systĂšmes Ă©ducatifs en question
La notion de « cadre » est de dĂ©veloppement rĂ©cent dans les organisations publiques, non pas que la hiĂ©rarchie des rĂŽles et des statuts en ait Ă©tĂ© absente, loin de lĂ , mais parce que le fonctionnement bureaucratique qui imprĂšgne leur tradition sâaccommodait mal de lâexistence dâune forme de responsabilitĂ© associant engagement dans lâaction collective et autonomie dâaction. Ce sont les dĂ©nonciations et les dĂ©fis auxquels lâadministration de lâaction publique a eu Ă rĂ©pondre au tournant des ann..
Interactions between BRCA2 and RAD51 for promoting homologous recombination in Leishmania infantum.
In most organisms, the primary function of homologous recombination (HR) is to allow genome protection by the faithful repair of DNA double-strand breaks. The vital step of HR is the search for sequence homology, mediated by the RAD51 recombinase, which is stimulated further by proteins mediators such as the tumor suppressor BRCA2. The biochemical interplay between RAD51 and BRCA2 is unknown in Leishmania or Trypanosoma. Here we show that the Leishmania infantum BRCA2 protein possesses several critical features important for the regulation of DNA recombination at the genetic and biochemical level. A BRCA2 null mutant, generated by gene disruption, displayed genomic instability and gene-targeting defects. Furthermore, cytological studies show that LiRAD51 can no longer localize to the nucleus in this mutant. The Leishmania RAD51 and BRCA2 interact together and the purified proteins bind single-strand DNA. Remarkably, LiBRCA2 is a recombination mediator that stimulates the invasion of a resected DNA double-strand break in an undamaged template by LiRAD51 to form a D-loop structure. Collectively, our data show that LiBRCA2 and LiRAD51 promote HR at the genetic and biochemical level in L. infantum, the causative agent of visceral leishmaniasis
Diphtheria in Lao PDR: insufficient coverage or ineffective vaccine?
Background
During late 2012 and early 2013 several outbreaks of diphthe-ria were notified in the North of the Lao Peopleâs Democratic Republic. The aim of this study was to determine whether the re-emergence of this vaccine-preventable disease was due to insufficient vaccination coverage or reduction of vaccine effectiveness within the affected regions.
Methods
A serosurvey was conducted in the Huaphan Province on a cluster sampling of 132 children aged 12â59 months. Serum samples, socio-demographic data, nutri-tional status and vaccination history were collected when available. Anti-diphtheria and anti-tetanus IgG antibody levels were measured by ELISA.
Results
Overall, 63.6% of participants had detectable diphtheria antibodies and 71.2% tetanus antibodies. Factors independently associated with non-vaccination against diphtheria were the distance from the health centre (OR: 6.35 [95% CI: 1.4â28.8], p = 0.01), the Lao Theung ethnicity (OR: 12.2 [95% CI:1,74â85, 4], p = 0.01) and the lack of advice on vac-cination given at birth (OR: 9.8 [95% CI: 1.5â63.8], (p = 0.01) while the level of maternal edu-cation was a protective factor (OR: 0.08 [95% CI: 0.008â0.81], p = 0.03). Most respondents claimed financial difficulties as the main reason for non-vaccination. Out of 55 children whose vaccination certificates stated that they were given all 3 doses of diphtheria-containing vaccine, 83.6% had diphtheria antibodies and 92.7% had tetanus antibodies. Furthermore, despite a high prevalence of stunted and underweight children (53% and 25.8%, respectively), the low levels of anti-diphtheria antibodies were not correlated to the nutritional status.
Conclusions
Our data highlight a significant deficit in both the vaccination coverage and diphtheria vaccine effectiveness within the Huaphan Province. Technical defi-ciencies in the methods of storage and distribution of vaccines as well as unreliability of vac-cination cards are discussed. Several hypotheses are advanced to explain such a decline in immunity against diphtheria and recommendations are provided to prevent future outbreaks
Hepatitis B virus in the Lao Peopleâs Democratic Republic: a cross sectional serosurvey in different cohorts
Background
Despite hepatitis B vaccination at birth and at 6, 10 and 14 weeks of age, hepatitis B virus (HBV) infection continues to be endemic in the Lao Peopleâs Democratic Republic (PDR). We carried out a cross-sectional serological study in infants, pre-school children, school pupils and pregnant women to determine their burden of disease, risk of infection and vaccination status.
Methods
A total of 2471 participants between 9 months and 46 years old were recruited from urban (Vientiane Capital, Luang Prabang), semi-urban (Boulhikhamxai and Savannakhet) and remote rural areas (Huaphan). All sera were tested for anti-HBs and anti-HBc. Sera testing positive for anti-HBc alone were further tested for the presence of HBsAg.
Results
A low prevalence of HBsAg (0.5%) was detected among infants from Vientiane and Luang Prabang, indicating some success of the vaccination policy. However, only 65.6% had protective anti-HBs antibodies, suggesting that vaccination coverage or responses remain sub-optimal, even in these urban populations.
In pre-school children from remote areas in Huaphan, 21.2% were positive for anti-HBc antibodies, and 4.6% were for HBsAg positive, showing that a significant proportion of children in these rural regions have early exposure to HBV. In pre-school children with 3 documented HBV vaccinations, only 17.0% (15/55) were serologically protected.
Among school-children from semi-urban regions of Luang Prabang, Boulhikhamxai and Savannakhet provinces, those below the age of 9 who were born after HBV vaccine introduction had anti-HBc and HBsAg prevalence of 11.7% and 4.1%, respectively. The prevalence increased to 19.4% and 7.8% of 10â14 year olds and to 27% and 10.2% of 15â19 year olds.
Pregnant women from Luang Prabang and Vientiane had very high anti-HBc and HBsAg prevalence (49.5% and 8.2%), indicating high exposure and risk of onward vertical transmission to the unborn infant.
Conclusions
Overall, the results demonstrate a dramatic deficiency in vaccination coverage and vaccine responses and/or documentation within the regions of Lao PDR studied, which included urbanized areas with better health care access. Timely and effective hepatitis B vaccination coverage is needed in Lao PDR
MRI Findings in 77 Children with Non-Syndromic Autistic Disorder
International audienceBACKGROUND: The clinical relevance of MR scanning in children with autism is still an open question and must be considered in light of the evolution of this technology. MRI was judged to be of insufficient value to be included in the standard clinical evaluation of autism according to the guidelines of the American Academy of Neurology and Child Neurology Society in 2000. However, this statement was based on results obtained from small samples of patients and, more importantly, included mostly insufficient MRI sequences. Our main objective was to evaluate the prevalence of brain abnormalities in a large group of children with a non-syndromic autistic disorder (AD) using T1, T2 and FLAIR MRI sequences. METHODOLOGY: MRI inspection of 77 children and adolescents with non-syndromic AD (mean age 7.4+/-3.6) was performed. All met the DSM-IV and ADI -R criteria for autism. Based on recommended clinical and biological screenings, we excluded patients with infectious, metabolic or genetic diseases, seizures or any other neurological symptoms. Identical MRI inspections of 77 children (mean age 7.0+/-4.2) without AD, developmental or neurological disorders were also performed. All MRIs were acquired with a 1.5-T Signa GE (3-D T1-FSPGR, T2, FLAIR coronal and axial sequences). Two neuroradiologists independently inspected cortical and sub-cortical regions. MRIs were reported to be normal, abnormal or uninterpretable. PRINCIPAL FINDINGS: MRIs were judged as uninterpretable in 10% (8/77) of the cases. In 48% of the children (33/69 patients), abnormalities were reported. Three predominant abnormalities were observed, including white matter signal abnormalities (19/69), major dilated Virchow-Robin spaces (12/69) and temporal lobe abnormalities (20/69). In all, 52% of the MRIs were interpreted as normal (36/69 patients). CONCLUSIONS: An unexpectedly high rate of MRI abnormalities was found in the first large series of clinical MRI investigations in non-syndromic autism. These results could contribute to further etiopathogenetic research into autism
Les disparités territoriales dans l'accÚs aux formations d'élite: La situation des Pays de la Loire au regard des autres régions françaises
La formation des Ă©lites demeure un sujet controversĂ© entre les partisans de la suppression des grandes Ă©coles, de leur fusion au sein des universitĂ©s ou de leur maintien. Alors que dans la plupart des autres pays lâUniversitĂ© assure seule la formation des Ă©lites, le systĂšme français est organisĂ© de telle sorte quâune partie des futures Ă©lites administratives, managĂ©riales, intellectuelles, politiques et scientifiques est sĂ©lectionnĂ©e, prĂ©parĂ©e et formĂ©e dans des structures non universitaires : les « grandes Ă©coles » et les classes prĂ©paratoires aux grandes Ă©coles (CPGE). Autre particularitĂ© du systĂšme : ces classes prĂ©paratoires relĂšvent de lâenseignement supĂ©rieur alors quâelles se situent dans des Ă©tablissements dâenseignement secondaire. InstituĂ©es au XVIIIe siĂšcle (Belhoste, 2003), elles accueillent actuellement 81135 Ă©tudiants, soit 3,5% des Ă©tudiants (RERS, 2010). Leur reprĂ©sentation nâa quasiment pas Ă©voluĂ© depuis 1970 (3,8%), malgrĂ© une croissance forte des effectifs, notamment durant la pĂ©riode 1985-1995 avec la crĂ©ation de nouvelles divisons, essentiellement dans les filiĂšres scientifiques et dans une moindre mesure, Ă©conomiques et commerciales.Ces classes suscitent de vives critiques : plus coĂ»teuses â le coĂ»t moyen dâun prĂ©parationnaire Ă©tait en 2007 de 15080 euros contre 9120 euros pour un Ă©tudiant des universitĂ©s â , faisant preuve dâune faible ouverture sociale (Euriat et ThĂ©lot, 1995 ; Duru-Bellat et Kieffer, 2008) â 51,1% dâenfants de cadre supĂ©rieur en 2009 vs 29,7% Ă lâUniversitĂ© â , territorialement inĂ©quitables (Bodin, 2007) â les effectifs sont concentrĂ©s en Ile-de-France et dans les grandes mĂ©tropoles rĂ©gionales â et dâune « productivitĂ© » moyenne (Michaut, Ă paraĂźtre) â sur 100 nĂ©o-inscrits en CPGE scientifiques , seuls 50% intĂ©greront une grande Ă©cole en deux annĂ©es de prĂ©paration et la situation est bien plus problĂ©matique dans la filiĂšre littĂ©raire avec seulement 8% dâintĂ©grĂ©s (Lemaire, 2008). A lâinverse, les « gardiens du temple » dĂ©fendent un modĂšle dâexcellence Ă la française qui favorise lâapprentissage de certaines compĂ©tences chez les Ă©tudiants, leur assurant ainsi une meilleure insertion professionnelle et de meilleurs salaires (Adangnikou, 2007 ; Giret, 2009).Les recherches se sont, jusquâĂ prĂ©sent, essentiellement focalisĂ©es sur le territoire national, sans faire apparaitre les Ă©ventuelles spĂ©cificitĂ©s des « prĂ©pas de proximitĂ© » ou des CPGE des Ă©tablissements privĂ©s. De mĂȘme, les caractĂ©ristiques, les conditions de travail et les reprĂ©sentations des enseignants qui font souvent figure dâĂ©lites dans le corps professoral du secondaire ont Ă©tĂ© peu Ă©tudiĂ©es. Ce rapport offre des Ă©lĂ©ments de rĂ©ponse en sâappuyant sur les recherches entreprises par des chercheurs du Centre de recherche en Ă©ducation de Nantes (CREN-UniversitĂ© de Nantes), du Centre Nantais en sociologie (CENS-UniversitĂ© de Nantes), du Laboratoire de Recherche en Education et Formation (LAREF-UniversitĂ© Catholique de lâOuest), du Laboratoire d'Economie et de Sociologie du Travail (LEST-CNRS) et de lâObservatoire sociologique du changement (OSC- Sciences.Po). Il Ă©claire Ă©galement les dĂ©bats sur les projets de rĂ©formes en cours (30% de boursiers en CPGE, dispositif dâouverture sociale) et aborde de nouvelles problĂ©matiques, notamment lâendorecrutement des Ă©tablissements.La recherche est articulĂ©e autour de quatre axes :- les disparitĂ©s territoriales de recrutement des classes prĂ©paratoires aux grandes Ă©coles ;- les conditions dâĂ©tudes et les parcours scolaires des Ă©tudiants des filiĂšres dâexcellence ;- Les stratĂ©gies des personnels des lycĂ©es ;- Les politiques d'ouverture sociale et les dispositifs innovants de lâEducation nationale, des collectivitĂ©s territoriales et des Ă©tablissements d'enseignement
Coupling Complete Blood Count and Steroidomics to Track Low Doses Administration of Recombinant Growth Hormone: An Anti-Doping Perspective
Growth Hormone (GH) under its human recombinant homologue (rhGH), may be abused by athletes to take advantage of its well-known anabolic and lipolytic properties; hence it is prohibited in sports by the World Anti-Doping Agency. Due to the rapid turnover of rhGH, anti-doping screening tests have turned to monitor two endocrine biomarkers (IGF-I and P-III-NP), but unfortunately, they show population-wise variability, limiting the identification rate of rhGH users. Previous studies have evidenced the numerous effects of GH on human physiology, especially in hematopoiesis and steroidogenesis. In this work, aiming to discover novel physiological rhGH biomarkers, we analyzed the complete blood count and the steroidomics profile of healthy, physically active, young males treated either with EPO + rhGH or EPO + placebo. The time-trends of these two physiological routes have been analyzed through geometric trajectory analysis (GTA) and OPLS-DA. Individuals supplemented with micro-doses of rhGH exhibited different leukopoietic and steroidal profiles compared to the control population, suggesting a role of the rhGH in both pathways. In the article, hypotheses on the observed differences are discussed according to the most recent literature and compared to results in animal models. The use of leukopoietic and steroidal biomarkers together with endocrine biomarkers (IGF-1 and P-III-NP) allows to correctly classify over 98% of samples with no false positives, miss-classifying only one single sample (false negative) over a total of 56; a promising result, if compared to the current rhGH detection strategies
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