Pmarg-pearlin is a matrix protein involved in nacre framework formation in the pearl oyster Pinctada margaritifera.

The shell of pearl oysters is organized in multiple layers of CaCO(3) crystallites packed together in an organic matrix. Relationships between the components of the organic matrix and mechanisms of nacre formation currently constitute the main focus of research into biomineralization. In this study, we characterized the pearlin protein from the oyster Pinctada margaritifera (Pmarg); this shares structural features with other members of a matrix protein family, N14/N16/pearlin. Pmarg pearlin exhibits calcium- and chitin-binding properties. Pmarg pearlin transcripts are distinctively localized in the mineralizing tissue responsible for nacre formation. More specifically, we demonstrate that Pmarg pearlin is localized within the interlamellar matrix of nacre aragonite tablets. Our results support recent models for multidomain matrix protein involvement in nacreous layer formation. We provide evidence here for the existence of a conserved family of nacre-associated proteins in Pteriidae, and reassess the evolutionarily conserved set of biomineralization genes related to nacre formation in this taxa.

Dual RNAseq highlights the kinetics of skin microbiome and fish host responsiveness to bacterial infection.

BACKGROUND: Tenacibaculum maritimum is a fish pathogen known for causing serious damage to a broad range of wild and farmed marine fish populations worldwide. The recently sequenced genome of T. maritimum strain NCIMB 2154T provided unprecedented information on the possible molecular mechanisms involved in the virulence of this species. However, little is known about the dynamic of infection in vivo, and information is lacking on both the intrinsic host response (gene expression) and its associated microbiota. Here, we applied complementary omic approaches, including dual RNAseq and 16S rRNA gene metabarcoding sequencing using Nanopore and short-read Illumina technologies to unravel the host-pathogen interplay in an experimental infection system using the tropical fish Platax orbicularis as model. RESULTS: We showed that the infection of the host is characterised by an enhancement of functions associated with antibiotic and glucans catabolism functions but a reduction of sulfate assimilation process in T. maritimum. The fish host concurrently displays a large panel of immune effectors, notably involving innate response and triggering acute inflammatory response. In addition, our results suggest that fish activate an adaptive immune response visible through the stimulation of T-helper cells, Th17, with congruent reduction of Th2 and T-regulatory cells. Fish were, however, largely sensitive to infection, and less than 25% survived after 96 hpi. These surviving fish showed no evidence of stress (cortisol levels) or significant difference in microbiome diversity compared with controls at the same sampling time. The presence of T. maritimum in resistant fish skin and the total absence of any skin lesions suggest that these fish did not escape contact with the pathogen, but rather that some mechanisms prevented pathogens entry. In resistant individuals, we detected up-regulation of specific immune-related genes differentiating resistant individuals from controls at 96 hpi, which suggests a possible genomic basis of resistance, although no genetic variation in coding regions was found. CONCLUSION: Here we focus in detail on the interplay between common fish pathogens and host immune response during experimental infection. We further highlight key actors of defence response, pathogenicity and possible genomic bases of fish resistance to T. maritimum.

Selective strategy for urethral catheterization in febrile young girls to confirm urinary tract infection diagnosis.

BACKGROUND: Urinary tract infections (UTIs) are a common source of bacterial infections in childhood. Making a proper diagnosis is important but requires invasive urine collection techniques. We aimed to derive a clinical decision rule to identify non-toilet-trained febrile girls at high risk for UTIs to restrict urethral catheterizations (UCs) to this high-risk group of patients. METHODS: We included all non-toilet-trained girls with a positive microscopic urinalysis from urine collected by sterile bag in a prospective cohort study to derive a model to predict UTI assessed by urine culture from UC. RESULTS: Thirty-seven patients were included. Absence of another source of fever on examination and the child's unusual behaviour were found to be independent predictors of UTI. The corresponding model offered an 85% sensitivity [95% confidence interval (CI): 56-96], with a 59% specificity (95% CI: 30-83) for UTI. The internal cross-validation by bootstrap led to an 85% sensitivity (95% CI: 68-100), and a 59% specificity (95% CI: 35-83). CONCLUSION: We derived a clinical decision model to selectively identify young febrile girls at high risk for UTI with a positive microscopic analysis and propose UC with an 85% sensitivity, which would avoid approximately 60% of unnecessary UCs; although further validation is necessary before daily clinical use.

[Children's soft tissue infections in tropical countries. Prospective study in Mayotte]. / Les infections des parties molles de l'enfant en milieu tropical. Etude prospective hospitalière à Mayotte.

In France and Europe, soft tissue infections are secondary to chickenpox infection. In tropical countries, soft tissue infections seem to be different and are more frequent. We conducted a prospective and descriptive study in children hospitalised for cellulitis. We studied characteristics of our population and we tried to individualize risk factors for deep soft tissue infections. 54 children were included over a six-month period. Blood cultures were positive in 10% and local culture in 62%. Pathogenic organisms to be found, were first Staphylococcus aureus (78%) and secondly alpha-haemolytic streptococcus. Average rate hospitalisation was 4.5 days (1-28). Despite intravenous antibiotherapy, more than one third of patients had had a deep soft tissue infection (myositis, abscess, or arthritis). As regards the overall population, deep soft tissue infections associated with cellulitis were more frequent in children over six. Association with arthritis was found only in children under two. Severe malnutrition seems to be a notable risk factor for myositis. Soft tissue infections are still frequent in tropical countries. Deep soft tissue infections are encountered in more than one third of the cases, specially in children over six, and with Staphylococcus aureus. These results justify a systematic hospitalisation. If severe malnutrition is present, association with myositis should be suspected.

[Febrile torticollis: an atypical presentation of Kawasaki disease]. / Un torticolis fébrile: présentation atypique d'une maladie de Kawasaki.

Kawasaki disease is a form of idiopathic systemic vasculitis. Diagnosis is based upon specific clinical parameters. Cardiac manifestations explain the mortality rate. They can be reduced by early treatment using intravenous immunoglobulin. Atypical Kawasaki disease is difficult to diagnose and can delay diagnosis. We report a case of Kawasaki disease with arthritis in a 4-year-old girl whose initial presentation was a febrile torticollis. A literature review details the atypical early signs of Kawasaki disease revealed by torticollis.

[Vestibular neuronitis in a teenager with sickle cell disease. Treatment is urgent]. / Syndrome vestibulaire chez une adolescente drépanocytaire SC. Le traitement est urgent.

Vestibular syndrome is not frequently described in patients with sickle cell disease. We report the case of a teenager with sickle cell disease who had a vestibular syndrome with vertigo that successfully responded to exchange transfusion. We discuss guidelines and review the literature in view of this case report. Sensorineural disorders should be considered as stroke syndromes. They require urgent treatment consisting of exchange transfusion or maintaining optimal hydration associated with blood withdrawal. Treatment of vestibular syndrome in sickle cell disease is urgent.

[Lemierre syndrome and influenza A (H1N1)]. / Syndrome de Lemierre et grippe A(H1N1).

Lemierre syndrome is an anaerobic bacteremia associated with a septic thrombophlebitis of the internal jugular vein. Septic emboli can be found in many organs. It often occurs after pharyngitis. Today, Lemierre syndrome is quite rare, but without rapid treatment, it may become life-threatening. A 4-year-old child presented with a febrile headache and torticollis. He was influenza A (H1N1)-positive. He also had beta-hemolytic streptococcal pharyngitis. A secondary CT scan was taken because of clinical worsening (non reducible torticollis). Parapharyngeal abscess and septic thrombophlebitis in the left jugular vein were revealed. In spite of negative blood cultures, our patient may have presented Lemierre syndrome. The outcome was favorable using intravenous antibiotics (metronidazole and penicillin) and curative anticoagulation. The thrombophlebitis vanished during a 2-month course of anticoagulation. Lemierre syndrome may occur after viral infections such as EBV or CMV infections. Like those viruses, influenza A (H1N1) virus may induce transient immunosuppression that predisposes to bacterial infections. Our patient had Lemierre syndrome occurring during an influenza A (H1N1) infection.

[Repeat visits in a pediatric emergency department]. / Consultations itératives aux urgences pédiatriques.

OBJECTIVE: The objective of this study was to characterize children who frequently use the pediatric emergency department. METHODS: This retrospective study selected children who consulted five times or more at the Pellegrin University Hospital emergency department in Bordeaux during the year 2006. We looked for risk factors for recurrent visits first in a comparative study and then conducted a phone survey with their GP. RESULTS: Among the 157 frequent-user children, 30.6% suffered from a chronic disease (more than half of them regularly seeing CHU doctors). For the other 59.4%, the risk factors for recurrent visits were age (children under the age of 1 year account for 35% of frequent users), distance from home to hospital (71.3% live within a 10-km perimeter), parental worry (44%), a precarious socioeconomic family situation, and being a beneficiary of the CMU (universal free health care coverage for low-income individuals) (37.6%). These children consulted more for a medical pathology (81.9%) than for a surgical pathology (18.1%) and were more often hospitalized (53.3% were hospitalized at least once). The degree to which these consultations followed an emergency situation was the same for both groups (i.e., 25% true emergencies). CONCLUSION: Approximately one-third of emergency department frequent-user children are children with a chronic disease, the others being young children, living close to the hospital, from unfavorable socioeconomic groups (using CMU health coverage), or with anxious parents.