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100 result(s) for "Renaud, Georges"
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The Epidemiology and Geographic Distribution of Relapsing Fever Borreliosis in West and North Africa, with a Review of the Ornithodoros erraticus Complex (Acari: Ixodida)
Relapsing fever is the most frequent bacterial disease in Africa. Four main vector / pathogen complexes are classically recognized, with the louse Pediculus humanus acting as vector for B. recurrentis and the soft ticks Ornithodoros sonrai, O. erraticus and O. moubata acting as vectors for Borrelia crocidurae, B. hispanica and B. duttonii, respectively. Our aim was to investigate the epidemiology of the disease in West, North and Central Africa. From 2002 to 2012, we conducted field surveys in 17 African countries and in Spain. We investigated the occurrence of Ornithodoros ticks in rodent burrows in 282 study sites. We collected 1,629 small mammals that may act as reservoir for Borrelia infections. Using molecular methods we studied genetic diversity among Ornithodoros ticks and Borrelia infections in ticks and small mammals. Of 9,870 burrows investigated, 1,196 (12.1%) were inhabited by Ornithodoros ticks. In West Africa, the southern and eastern limits of the vectors and Borrelia infections in ticks and small mammals were 13°N and 01°E, respectively. Molecular studies revealed the occurrence of nine different Ornithodoros species, including five species new for science, with six of them harboring Borrelia infections. Only B. crocidurae was found in West Africa and three Borrelia species were identified in North Africa: B. crocidurae, B. hispanica, and B. merionesi. Borrelia Spirochetes responsible for relapsing fever in humans are highly prevalent both in Ornithodoros ticks and small mammals in North and West Africa but Ornithodoros ticks seem absent south of 13°N and small mammals are not infected in these regions. The number of Ornithodoros species acting as vector of relapsing fever is much higher than previously known.
Accuracy of automated machine learning in classifying retinal pathologies from ultra-widefield pseudocolour fundus images
AimsAutomated machine learning (AutoML) is a novel tool in artificial intelligence (AI). This study assessed the discriminative performance of AutoML in differentiating retinal vein occlusion (RVO), retinitis pigmentosa (RP) and retinal detachment (RD) from normal fundi using ultra-widefield (UWF) pseudocolour fundus images.MethodsTwo ophthalmologists without coding experience carried out AutoML model design using a publicly available image data set (2137 labelled images). The data set was reviewed for low-quality and mislabeled images and then uploaded to the Google Cloud AutoML Vision platform for training and testing. We designed multiple binary models to differentiate RVO, RP and RD from normal fundi and compared them to bespoke models obtained from the literature. We then devised a multiclass model to detect RVO, RP and RD. Saliency maps were generated to assess the interpretability of the model.ResultsThe AutoML models demonstrated high diagnostic properties in the binary classification tasks that were generally comparable to bespoke deep-learning models (area under the precision-recall curve (AUPRC) 0.921–1, sensitivity 84.91%–89.77%, specificity 78.72%–100%). The multiclass AutoML model had an AUPRC of 0.876, a sensitivity of 77.93% and a positive predictive value of 82.59%. The per-label sensitivity and specificity, respectively, were normal fundi (91.49%, 86.75%), RVO (83.02%, 92.50%), RP (72.00%, 100%) and RD (79.55%,96.80%).ConclusionAutoML models created by ophthalmologists without coding experience can detect RVO, RP and RD in UWF images with very good diagnostic accuracy. The performance was comparable to bespoke deep-learning models derived by AI experts for RVO and RP but not for RD.
The Recent Evolution of a Maternally-Inherited Endosymbiont of Ticks Led to the Emergence of the Q Fever Pathogen, Coxiella burnetii
Q fever is a highly infectious disease with a worldwide distribution. Its causative agent, the intracellular bacterium Coxiella burnetii, infects a variety of vertebrate species, including humans. Its evolutionary origin remains almost entirely unknown and uncertainty persists regarding the identity and lifestyle of its ancestors. A few tick species were recently found to harbor maternally-inherited Coxiella-like organisms engaged in symbiotic interactions, but their relationships to the Q fever pathogen remain unclear. Here, we extensively sampled ticks, identifying new and atypical Coxiella strains from 40 of 58 examined species, and used this data to infer the evolutionary processes leading to the emergence of C. burnetii. Phylogenetic analyses of multi-locus typing and whole-genome sequencing data revealed that Coxiella-like organisms represent an ancient and monophyletic group allied to ticks. Remarkably, all known C. burnetii strains originate within this group and are the descendants of a Coxiella-like progenitor hosted by ticks. Using both colony-reared and field-collected gravid females, we further establish the presence of highly efficient maternal transmission of these Coxiella-like organisms in four examined tick species, a pattern coherent with an endosymbiotic lifestyle. Our laboratory culture assays also showed that these Coxiella-like organisms were not amenable to culture in the vertebrate cell environment, suggesting different metabolic requirements compared to C. burnetii. Altogether, this corpus of data demonstrates that C. burnetii recently evolved from an inherited symbiont of ticks which succeeded in infecting vertebrate cells, likely by the acquisition of novel virulence factors.
In Vitro Investigation of Equine Gut Microbiota Alterations During Hypoglycin A Exposure
Hypoglycin A is a plant-derived protoxin that causes atypical myopathy in equids. In atypical myopathy-affected horses, metabolomic and microbiome studies have reported alterations in metabolic markers and faecal microbiota composition, pointing to a potential disruption of microbial homeostasis. However, in vivo observations are strongly confounded by host-related factors, underscoring the need for controlled in vitro approaches. To address this, we used an in vitro static batch fermentation model simulating the equine colon to investigate the direct effects of hypoglycin A on microbiota composition and activity. Faecal inocula from healthy horses were incubated in control and hypoglycin A-treated fermenters for 48 h, with serial analyses of hypoglycin A concentration, short-chain fatty acids, and 16S rRNA gene profiles. Hypoglycin A remained stable in the nutritive medium in the absence of microbiota, confirming that its degradation in inoculated fermenters was microbiota-dependent. The results showed significant microbial-associated hypoglycin A degradation without evidence of toxic metabolite formation. The analysis of α- and β-diversity revealed both an effect of incubation time, reflecting the natural temporal dynamics of microbial communities under batch fermentation, and a specific impact of hypoglycin A exposure, with certain taxa such as Paraclostridium being affected. This study provides the first in vitro evidence that the equine microbiota contributes to hypoglycin A degradation.
Laparoscopic transperitoneal pudendal nerve and artery release for pudendal entrapment syndrome
IntroductionPudendal nerve and artery entrapment is an underdiagnosed pathology responsible of several urinary, sexual and anorectal complaints. The aim of our study was to evaluate safety and feasibility of laparoscopic transperitoneal pudendal nerve and artery release in a large retrospective cohort of patients with pudendal nerve entrapment syndrome with both a short and long-term follow-up. Technical details and outcomes are also reported.MethodsA series of 235 patients with pudendal syndrome underwent laparoscopic transperitoneal pudendal canal release between June 2015 and February 2020. Operative data were recorded prospectively for all patients. A complete history, pain visual analog scale (VAS) for perineodynia, and three scores evaluating the main symptoms (USP, IIEF-5, PAC-SYM) were obtained before and at least 24 months after surgery for 32 patients only. Post-operative complications were also evaluated using Clavien-Dindo classification at regular interval.ResultsThe mean operating time per side was 33.9 ± 6.8 min and the average hospital stay was 1.9 ± 0.3 days. Blood loss was 20 cc ± 10 cc with no patients needing transfusion. The only significant per-operative complication was hemorrhage (600 ml) in one patient induced by a pudendal artery laceration, successfully treated by laparoscopic suturing. Post-operative complications were noted in 18.7% of patients with no serious Clavien-Dindo complications. Perineodynia VAS dropped from 6.8 ± 0.9 to 2.2 ± 1.8 after surgery (p < 0.001). Mean IIEF-5 scores significantly improved one month after the surgery (15.2 vs 19.3, p = 0.036). Mean USP scores significantly improved for the dysuria domain (4.2 vs 1.6, p = 0.021) but not for stress urinary incontinence (3.9 vs 4.1, p = 0.082) or overactive bladder symptoms (14.1 vs 13.8, p = 0.079). Mean PAC-SYM scores significantly improved after the procedure (1.8 vs 1.1, p < 0.001).ConclusionA complete laparoscopic pudendal nerve and artery release, from the sciatic spine through the Alcock’s canal, is a fast and safe surgery with promising functional results. A large prospective trial is needed to validate such an approach.
Medical students’ perception of simulation-based assessment in emergency and paediatric medicine: a focus group study
Background Although simulation-based assessment (SBA) is being implemented in numerous medical education systems, it is still rarely used for undergraduate medical students in France. Objective structured clinical examinations (OSCEs) will be integrated into the national medical curriculum in 2021. In 2016 and 2017, we created a mannequin SBA to validate medical students’ technical and psychometric skills during their emergency medicine and paediatric placements. The aim of our study was to determine medical students’ perceptions of SBA. Methods We followed the grounded theory framework to conduct a qualitative study. A total of 215 students participated in either a paediatric or an emergency medicine simulation-based course with a final assessment. Among the 215 participants, we randomly selected forty students to constitute the focus groups. In the end, 30 students were interviewed. Data were coded and analysed by two independent investigators within the activity theory framework. Results The analyses found four consensual themes. First, the students perceived that success in the SBA provided them with self-confidence and willingness to participate in their hospital placements (1). They considered SBA to have high face validity (2), and they reported changes in their practice after its implementation (3). Nevertheless, they found that SBA did not help with their final high-stakes assessments (4). They discussed three other themes without reaching consensus: stress, equity, and the structure of SBA. After an analysis with activity theory, we found that students’ perceptions of SBA underlined the contradictions between two systems of training: hospital and medical. We hypothesise that a specific role and place for SBA should be defined between these two activity systems. Conclusion The students perceived that SBA would increase self-confidence in their hospital placements and emphasise the general skills required in their future professional environment. However, they also reported that the assessment method might be biased and stressful. Our results concerning a preimplementation mannequin SBA and OSCE could provide valuable insight for new programme design and aid in improving existing programmes. Indeed, SBA seems to have a role and place between hospital placements and medical schools.