Quoi de neuf en medecine des voyages? [What's new in travel medicine?]

Les menaces pour la santé des voyageurs proviennent souvent de l'émergence ou de la réémergence d'anciennes et de nouvelles maladies infectieuses. En Amérique du Sud c'est une augmentation des cas de fièvre jaune qui a fait du bruit. A Bornéo, une nouvelle espèce de Plasmodium pathogène pour l'humain a été mise en évidence. Après l'épidémie sur les îles de l'océan Indien, le virus du Chikungunya a causé de nouveaux foyers et ceci même en Europe. La première journée mondiale de la rage a rappelé que cette maladie continue à tuer un nombre important de personnes dans les pays aux ressources limitées. La rage affecte également des personnes de nos pays comme l'illustre deux situations récentes. Finalement, le nouveau Règlement sanitaire international permettra à l'OMS de mieux répondre aux urgences de santé publique de portée internationale. The threats for the health of travellers come often from the emergence or the re-emergence of old and new infectious diseases. In South America an important increase of the number of cases of yellow fever was reported. On the island of Borneo a new species of Plasmodium pathogenic for humans has been identified. After the Chikungunya epidemic that affected the islands of the Indian Ocean, the virus has caused new epidemic foci and this even in Europe. The first World Rabies Day reminded us that this disease still kills a large number of persons in countries with limited resources. Rabies can also affect persons from our countries, as it was illustrated by two recent situations. Finally the new International Health Regulation will allow the WHO to better respond to public health emergencies of international concern

Genetics of essential tremor.

Essential tremor (ET) is a prevalent condition manifesting with progressive action tremor. Although ET was traditionally viewed as a sporadic disease, a significant proportion of cases report a positive family history of tremor. Autosomal dominant inheritance can be demonstrated in many families. Previously, genome-wide linkage studies in families mapped three loci for ET, hereditary essential tremor-1 (ETM1), ETM2 and ETM3. However, no causal mutation has been replicated in candidate genes within these loci, including dopamine D3 receptor (DRD3) and HS1-binding protein 3 (HS1BP3). Recently, the first genome-wide association study in ET followed by replication studies conducted in diverse populations identified a significant association between the leucine-rich repeat and Ig domain containing 1 gene (LINGO1) SNP rs9652490 and risk for ET Although further novel variants were indentified in LINGO1 and its paralog LINGO2 that may be associated with risk for ET, the pathogenic mechanisms involved remain elusive. Given the possibility that ET as a complex trait may be influenced by the combined effects of rare variants, novel high-throughput technologies sequencing all exons across the genome (exome sequencing) or the whole genome (genome sequencing) may become crucial in understanding/deciphering the genetic background of ET.

Fenofibrate: a new treatment for diabetic retinopathy. Molecular mechanisms and future perspectives.

Despite improving standards of care, people with diabetes remain at risk of development and progression of diabetic retinopathy (DR) and visual impairment. Identifying novel therapeutic approaches, preferably targeting more than one pathogenic pathway in DR, and at an earlier stage of disease, is attractive. There is now consistent evidence from two major trials, the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study and the Action to Control Cardiovascular Risk in Diabetes Eye (ACCORD-Eye) study, totalling 11,388 people with type 2 diabetes (5,701 treated with fenofibrate) that fenofibrate reduces the risk of development and progression of DR. Therefore, fenofibrate may be considered a preventive strategy for patients without DR or early intervention strategy for those with mild DR. A number of putative therapeutic mechanisms for fenofibrate, both dependent and independent of lipids, have been proposed. A deeper understanding of the mode of action of fenofibrate will further help to define how best to use fenofibrate clinically as an adjunct to current management of DR.

The sigma factor AlgU (AlgT) controls exopolysaccharide production and tolerance towards desiccation and osmotic stress in the biocontrol agent Pseudomonas fluorescens CHA0.

A variety of stress situations may affect the activity and survival of plant-beneficial pseudomonads added to soil to control root diseases. This study focused on the roles of the sigma factor AlgU (synonyms, AlgT, RpoE, and sigma(22)) and the anti-sigma factor MucA in stress adaptation of the biocontrol agent Pseudomonas fluorescens CHA0. The algU-mucA-mucB gene cluster of strain CHA0 was similar to that of the pathogens Pseudomonas aeruginosa and Pseudomonas syringae. Strain CHA0 is naturally nonmucoid, whereas a mucA deletion mutant or algU-overexpressing strains were highly mucoid due to exopolysaccharide overproduction. Mucoidy strictly depended on the global regulator GacA. An algU deletion mutant was significantly more sensitive to osmotic stress than the wild-type CHA0 strain and the mucA mutant were. Expression of an algU'-'lacZ reporter fusion was induced severalfold in the wild type and in the mucA mutant upon exposure to osmotic stress, whereas a lower, noninducible level of expression was observed in the algU mutant. Overexpression of algU did not enhance tolerance towards osmotic stress. AlgU was found to be essential for tolerance of P. fluorescens towards desiccation stress in a sterile vermiculite-sand mixture and in a natural sandy loam soil. The size of the population of the algU mutant declined much more rapidly than the size of the wild-type population at soil water contents below 5%. In contrast to its role in pathogenic pseudomonads, AlgU did not contribute to tolerance of P. fluorescens towards oxidative and heat stress. In conclusion, AlgU is a crucial determinant in the adaptation of P. fluorescens to dry conditions and hyperosmolarity, two major stress factors that limit bacterial survival in the environment.

Amoeba/amoebal symbiont genetic transfers: lessons from giant virus neighbours.

Free-living amoebae serve as hosts for a variety of amoebae-resisting microorganisms, including giant viruses and certain bacteria. The latter include symbiotic bacteria as well as bacteria exhibiting a pathogenic phenotype towards amoebae. Amoebae-resisting bacteria have been shown to be widespread in water and to use the amoebae as a reservoir, a replication niche, a protective armour as well as a training ground to select virulence traits allowing survival in the face of microbicidal effects of macrophages, the first line of defense against invading pathogens. More importantly, amoebae play a significant role as a melting pot for genetic exchanges. These ecological and evolutionary roles of amoebae might also be at play for giant viruses and knowledge derived from the study of amoebae-resisting bacteria is useful for the study and understanding of interactions between amoebae and giant viruses. This is especially important since some genes have spread in all domains of life and the exponential availability of eukaryotic genomes and metagenomic sequences will allow researchers to explore these genetic exchanges in a more comprehensive way, thus completely changing our perception of the evolutionary history of organisms. Thus, a large part of this review is dedicated to report current known gene exchanges between the different amoebae-resisting organisms and between amoebae and the internalized bacteria.

Micobiota associada a folhas de bananeira em Cabo Verde

A bananeira tem um elevado valor social e económico para Cabo Verde, desempenhando um papel fundamental na dieta alimentar das populações. Nos últimos anos a produtividade da cultura tem vindo a decair e de entre as causas responsáveis pelo declínio dos bananais incluem-se micoses. Com a finalidade de determinar o possível envolvimento de fungos nas doenças foliares fez-se o levantamento da micobiota associada a necroses foliares. Material foliar com lesões de diversos tipos foi recolhido em bananais de 10 localidades da Ilha de Santiago e observado ou colocado em câmara húmida sobre meio gelosado. As estruturas de fungos detectadas sobre as folhas foram montadas em lactofenol e utilizadas para identificação até ao nível da espécie, dos fungos registados, utilizando para o efeito critérios clássicos em sistemática micológica. Foram identificados 48 táxones, sendo 44 fungos mitospóricos e 4 fungos ascomicetas. Muitos dos fungos identificados não são considerados fitopatogénicos na bananeira, estando referidos como endófitos ou saprófitas na cultura. Os principais fungos patogénicos identificados foram Cladosporium musae, Colletotrichum gloeosporiodes, C. musae, Cordana musae, Deightoniella torulosa, Lasiodiplodia theobromae e Ramichloridium musae. A maioria das espécies apresentou larga distribuição nas zonas de produção amostradas.

Behavioral phenotyping of glutathione-deficient mice: Relevance to schizophrenia and bipolar disorder.

Redox-dysregulation represents a common pathogenic mechanism in schizophrenia (SZ) and bipolar disorder (BP). It may in part arise from a genetically compromised synthesis of glutathione (GSH), the major cellular antioxidant and redox-regulator. Allelic variants of the genes coding for the rate-limiting GSH synthesizing enzyme glutamate-cysteine-ligase modifier (GCLM) and/or catalytic (GCLC) subunit have been associated with SZ and BP. Using mice knockout (KO) for GCLM we have previously shown that impaired GSH synthesis is associated with morphological, functional and neurochemical anomalies similar to those in patients. Here we asked whether GSH deficit is also associated with SZ- and BP-relevant behavioral and cognitive anomalies. Accordingly, we subjected young adult GCLM-wildtype (WT), heterozygous and KO males to a battery of standard tests. Compared to WT, GCLM-KO mice displayed hyperlocomotion in the open field and forced swim test but normal activity in the home cage, suggesting that hyperlocomotion was selective to environmental novelty and mildly stressful situations. While spatial working memory and latent inhibition remained unaffected, KO mice showed a potentiated hyperlocomotor response to an acute amphetamine injection, impaired sensorymotor gating in the form of prepulse inhibition and altered social behavior compared to WT. These anomalies resemble important aspects of both SZ and the manic component of BP. As such our data support the notion that redox-dysregulation due to GSH deficit is implicated in both disorders. Moreover, our data propose the GCLM-KO mouse as a valuable model to study the behavioral and cognitive consequences of redox dysregulation in the context of psychiatric disease.

Parachlamydia acanthamoebae, an emerging agent of pneumonia.

Parachlamydia acanthamoebae is a Chlamydia-like organism that easily grows within Acanthamoeba spp. Thus, it probably uses these widespread free-living amoebae as a replicative niche, a cosmopolite aquatic reservoir and a vector. A potential role of P. acanthamoebae as an agent of lower respiratory tract infection was initially suggested by its isolation within an Acanthamoeba sp. recovered from the water of a humidifier during the investigation of an outbreak of fever. Additional serological and molecular-based investigations further supported its pathogenic role, mainly in bronchiolitis, bronchitis, aspiration pneumonia and community-acquired pneumonia. P. acanthamoebae was shown to survive and replicate within human macrophages, lung fibroblasts and pneumocytes. Moreover, this strict intracellular bacterium also causes severe pneumonia in experimentally infected mice, thus fulfilling the third and fourth Koch criteria for a pathogenic role. Consequently, new tools have been developed for the diagnosis of parachlamydial infections. It will be important to routinely search for this emerging agent of pneumonia, as P. acanthamoebae is apparently resistant to quinolones, which are antibiotics often used for the empirical treatment of atypical pneumonia. Other Chlamydia-related bacteria, including Protochlamydia naegleriophila, Simkania negevensis and Waddlia chondrophila, might also cause lung infections. Moreover, several additional novel chlamydiae, e.g. Criblamydia sequanensis and Rhabdochlamydia crassificans, have been discovered and are now being investigated for their human pathogenicity.

The sand rat, Psammomys obesus, develops type 2 diabetic retinopathy similar to humans.

PURPOSE: Diabetic retinopathy (DR) is a leading cause of blindness, yet pertinent animal models are uncommon. The sand rat (Psammomys obesus), exhibiting diet-induced metabolic syndrome, might constitute a relevant model. METHODS: Adult P. obesus (n = 39) were maintained in captivity for 4 to 7 months and fed either vegetation-based diets (n = 13) or standard rat chow (n = 26). Although plant-fed animals exhibited uniform body weight and blood glucose levels over time, nearly 60% of rat chow-raised animals developed diabetes-like symptoms (test group). Animals were killed, and their eyes and vitreous were processed for immunochemistry. RESULTS: Compared with plant-fed animals, diabetic animals showed many abnormal vascular features, including vasodilation, tortuosity, and pericyte loss within the blood vessels, hyperproteinemia and elevated ratios of proangiogenic and antiangiogenic growth factors in the vitreous, and blood-retinal barrier breakdown. Furthermore, there were statistically significant decreases in retinal cell layer thicknesses and densities, accompanied by profound alterations in glia (downregulation of glutamine synthetase, glutamate-aspartate transporter, upregulation of glial fibrillar acidic protein) and many neurons (reduced expression of protein kinase Cα and Cξ in bipolar cells, axonal degeneration in ganglion cells). Cone photoreceptors were particularly affected, with reduced expression of short- and mid-/long-wavelength opsins. Hypercaloric diet nondiabetic animals showed intermediate values. CONCLUSIONS: Simple dietary modulation of P. obesus induces a rapid and severe phenotype closely resembling human type 2 DR. This species presents a valuable novel experimental model for probing the neural (especially cone photoreceptor) pathogenic modifications that are difficult to study in humans and for screening therapeutic strategies.

Prenatal presentation and postnatal evolution of a patient with Jansen metaphyseal dysplasia with a novel missense mutation in PTH1R.

Wave-shaped ribs were detected at prenatal ultrasound in a 20(+1) week female fetus. At birth, skeletal radiographs showed marked hypomineralization and suggested hypophosphatasia. However, elevated blood calcium and alkaline phosphatase excluded hypophosphatasia and raised the possibility of Jansen metaphyseal dysplasia. Molecular analysis of the PTH/PTHrP receptor gene (PTH1R) showed heterozygosity for a previously undescribed transversion variant (c.1373T>A), which predicts p.Ile458Lys. In vitro evaluation of wild type and mutant PTH/PTHrP receptors supported the pathogenic role of the p.Ile458Lys substitution, and confirmed the diagnosis of Jansen metaphyseal dysplasia. This disorder may present prenatally with wavy ribs and in the newborn with hypomineralization, and may therefore be confused with hypophosphatasia. The mottled metaphyseal lesions typically associated with this disease appear only in childhood.

A missense mutation in myelin oligodendrocyte glycoprotein as a cause of familial narcolepsy with cataplexy.

Narcolepsy is a rare sleep disorder characterized by excessive daytime sleepiness and cataplexy. Familial narcolepsy accounts for less than 10% of all narcolepsy cases. However, documented multiplex families are very rare and causative mutations have not been identified to date. To identify a causative mutation in familial narcolepsy, we performed linkage analysis in the largest ever reported family, which has 12 affected members, and sequenced coding regions of the genome (exome sequencing) of three affected members with narcolepsy and cataplexy. We successfully mapped a candidate locus on chromosomal region 6p22.1 (LOD score ¼ 3.85) by linkage analysis. Exome sequencing identified a missense mutation in the second exon of MOG within the linkage region. A c.398C>G mutation was present in all affected family members but absent in unaffected members and 775 unrelated control subjects. Transient expression of mutant myelin oligodendrocyte glycoprotein (MOG) in mouse oligodendrocytes showed abnormal subcellular localization, suggesting an altered function of the mutant MOG. MOG has recently been linked to various neuropsychiatric disorders and is considered as a key autoantigen in multiple sclerosis and in its animal model, experimental autoimmune encephalitis. Our finding of a pathogenic MOG mutation highlights a major role for myelin and oligodendrocytes in narcolepsy and further emphasizes glial involvement in neurodegeneration and neurobehavioral disorders. [corrected].

VARIABILITY OF PHENOTYPIC, PROTEOMIC AND TRANSCRIPTOMIC EXPRESSION OF STAPHYLOCOCCUS AUREUS SURFACE ADHESINS

Staphylococcus aureus is a highly successful pathogen responsible of a wide variety of diseases, from minor skin infection to life-threatening sepsis or infective endocarditis, as well as food poisoning and toxic shock syndrome. This heterogeneity of infections and the ability of S. aureus to develop antibiotic-resistance to virtually any available drugs reflect its extraordinary capacity to adapt and survive in a great variety of environments. The pathogenesis of S. aureus infection involves a wide range of cell wall-associated adhesins and extracellular toxins that promote host colonization and invasion. In addition, S. aureus is extremely well equipped with regulatory systems that sense environmental conditions and respond by fine tuning the expression of metabolic and virulence determinants. Surface adhesins referred to MSCRAMMs - for Microbial Surface Component Recognizing Adherence Matrix Molecules - mediate binding to the host extracellular matrix or serum components, including fibrinogen, fibronectin, collagen and elastin, and promote tissue colonization and invasion. Major MSCRAMMs include a family of surface-attached proteins covalently bound to the cell wall peptidoglycan via a conserved LPXTG motif. Genomic analyses indicate that S. aureus contain up to 22 LPXTG surface proteins, which could potentially act individually or in synergy to promote infection. In the first part of this study we determined the range of adherence phenotypes to fibrinogen and fibronectin among 30 carriage isolates of S. aureus and compared it to the adherence phenotypes of 30 infective endocarditis and 30 blood culture isolates. Overall there were great variations in in vitro adherence, but no differences were observed between carriage and infection strains. We further determined the relation between in vitro adherence and in vivo infectivity in a rat model of experimental endocarditis, using 4 isolates that displayed either extremely low or high adherence phenotypes. Unexpectedly, no differences were observed between the in vivo infectivity of isolates that were poorly and highly adherent in vitro. We concluded that the natural variability of in vitro adherence to fibrinogen and fibronectin did not correlate with in vivo infectivity, and thus that pathogenic differences between various strains might only be expressed in in vivo conditions, but not in vitro. Therefore, considering the importance of adhesins expression for infection, direct measurement of those adhesins present on the bacterial surface were made by proteomic approach. 5 In the second series of experiments we assessed the physical presence of the LPXTG species at the staphylococcal surface, as measured at various time points during growth in different culture media. S. aureus Newman was grown in either tryptic soy broth (TSB) or in Roswell Park Memorial Institute (RPMI) culture medium, and samples were removed from early exponential growth phase to late stationary phase. Experiments were performed with mutants in the global accessory-gene regulator (agr), surface protein A (Spa) and clumping factor A (ClfA). Peptides of surface proteins were recovered by "trypsin-shaving" of live bacteria, and semi-quantitative proteomic analysis was performed by tandem liquid-chromatography and mass-spectrometry (LC-MS). We also determined in parallel the mRNA expression by microarrays analysis, as well as the phenotypic adherence of the bacteria to fibrinogen in vitro. The surface proteome was highly complex and contained numerous proteins theoretically not belonging to the bacterial envelope, including ribosomal proteins and metabolic enzymes. Sixteen of the 21 known LPXTG species were detected, but were differentially expressed. As expected, 9 known agr-regulated proteins (e.g. including Spa, FnBPA, ClfA, IsdA, IsdB, SasH, SasD, SasG and FmtB) increased up to the late exponential growth phase, and were abrogated in agr-negative mutants. However, only Spa and SasH modified their proteomic and mRNA profiles in parallel in the parent and its agr negative mutant, while all other LPXTG proteins modified their proteomic profiles independently of their mRNA. Moreover, ClfA became highly transcribed and active in in vitro fibrinogen adherence tests during late growth (24h), whereas it remained poorly detected by proteomics. Differential expression was also detected in iron-rich TSB versus iron-poor RPMI. Proteins from the iron-regulated surface determinant (isd) system, including IsdA, IsdB and IsdH were barely expressed in iron-rich TSB, whereas they increased their expression by >10 time in iron-poor RPMI. We conclude that semi-quantitative proteomic analysis of specific protein species is feasible in S. aureus and that proteomic, transcriptomic and adherence phenotypes demonstrated differential profiles in S. aureus. Furthermore, peptide signatures released by trypsin shaving suggested differential protein domain exposures in various environments, which might be relevant for antiadhesins vaccines. A comprehensive understanding of the S. aureus physiology should integrate all these approaches.

Genomics of secondary metabolite production by Pseudomonas fluorescens Pf-5

The complete sequence of the 7.07 Mb genome of the biological control agent Pseudomonas fluorescens Pf-5 is now available, providing a new opportunity to advance knowledge of biological control through genomics. P. fluorescens Pf-5 is a rhizosphere bacterium that suppresses seedling emergence diseases and produces a spectrum of antibiotics toxic to plant-pathogenic fungi and oomycetes. In addition to six known secondary metabolites produced by Pf-5, three novel secondary metabolite biosynthesis gene clusters identified in the genome could also contribute to biological control. The genomic sequence provides numerous clues as to mechanisms used by the bacterium to survive in the spermosphere and rhizosphere. These features include broad catabolic and transport capabilities for utilizing seed and root exudates, an expanded collection of efflux systems for defense against environmental stress and microbial competition, and the presence of 45 outer membrane receptors that should allow for the uptake of iron from a wide array of siderophores produced by soil microorganisms. As expected for a bacterium with a large genome that lives in a rapidly changing environment, Pf-5 has an extensive collection of regulatory genes, only some of which have been characterized for their roles in regulation of secondary metabolite production or biological control. Consistent with its commensal lifestyle, Pf-5 appears to lack a number of virulence and pathogenicity factors found in plant pathogen.

Biosafety of Recombinant Adeno-associated Virus Vectors.

It is hoped that the use of gene transfer technology to treat both monogenetic and acquired diseases may soon become a common therapy option in medicine. For gene therapy to achieve this objective, any gene delivery method will have to meet several criteria, including ease of manufacturing, efficient gene transfer to target tissue, long-term gene expression to alleviate the disease, and most importantly safety in patients. Viral vectors are an attractive choice for use in gene therapy protocols due to their relative efficiency in gene delivery. Since there is inherent risk in using viruses, investigators in the gene therapy community have devoted extensive efforts toward reengineering viral vectors for enhance safety. Here we review the approaches and technologies that are being evaluated for the use of recombinant vectors based upon adeno-associated virus (AAV) in the treatment of a variety of human diseases. AAV is currently the only known human DNA virus that is non-pathogenic and AAV-based vectors are classified as Risk Group 1 agents for all laboratory and animal studies carried out in the US. Although its apparent safety in natural infection and animals appears well documented, we examine the accumulated knowledge on the biology and vectorology of AAV, lessons learned from gene therapy clinical trials, and how this information is impacting current vector design and manufacturing with an overall emphasis on biosafety.

O Papel do Ar e Água Ambientais como Veículos de Transmissão de Infeções Fúngicas no Hospital Agostinho Neto, Cidade da Praia, Cabo Verde

Os fungos são um grupo de microrganismos diversificado com uma grande ubiquidade na natureza, podendo ser encontrados no solo, no ar e na água. Alguns destes microrganismos são considerados como verdadeiros agentes patogénicos para humanos e, embora na grande maioria sejam inofensivos para indivíduos saudáveis, tornam-se patogénicos para indivíduos com fragilidade imunológica. A infeção por estes agentes em ambiente hospitalar tem sido relatada neste últimos anos como a principal causa de morte nos pacientes internados com debilidade imunológica. Neste estudo foi feita a monitorização da presença de fungos no ambiente de algumas unidades mais críticas do Hospital Agostinho Neto na cidade da Praia em Cabo Verde durante o mês de Janeiro de 2012, nomeadamente no Bloco Operatório do hospital, no serviço de internamento Cirúrgico e Queimadura, no serviço de internamento de Neonatologia, no serviço de internamento de Infeciologia, no serviço de Oncologia e no serviço de Hemodiálise. No total foram recolhidas 34 amostras de diferentes locais, detectadas 393ufc/m3 no ar, 685ufc/m3 na água e 2696ufc/m2 nas superfícies e isolados 104 fungos morfologicamente diferentes, sendo sido obtidos 29 a partir do ar, 21 de amostras da água e 54 de superfícies. A análise micológica destas amostras revelou uma forte presença dos géneros como Penicillium sp., Cladosporium sp. e Aspergillus sp. em todas as colheitas. Sabendo que a contaminação do ambiente hospitalar por estes agentes pode ser um fator de risco para infeção nosocomial em pacientes com sistema imunitário muito debilitado, sugerimos no final do trabalho algumas linhas orientadoras para minimizar os fatores de risco e propor trabalhos futuros para correlacionar esses fatores com casos de ocorrência de infeções fúngicas no Hospital Agostinho Neto na cidade da Praia, Cabo Verde.