33 research outputs found

    Pathways of the Modified Atlantic Water across the Strait of Sicily

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    The purpose of this study is to study the medium-scale dynamics, as well as the dynamics of the sub-basin scale in the Central Mediterranean, and to elucidate the routes of the Atlantic waters in this region using a high-resolution numerical model of the eddy-resolving simplest equation. The seasonal variability of the two streams of modified Atlantic waters crossing the Sicilian Strait varies considerably. The main stream along the coast of Tunisia, giving rise to the Atlantic Tunisian current, is stronger than the Atlantic Ionian stream (AIP) from autumn to spring. The Atlantic Tunisian current, which, apparently, is present throughout the year, is characterized by high spatial and temporal variability from the simulation results. The high-resolution model is capable of well reproducing the flow and variability of AIP, including such associating characteristic structures as the Advent Benk Vortex, Moltis Channel Cross, Ionian Benc Vortex and the outflow to the northern Ionian Sea

    Temporal Dynamics and Impact of Climate Factors on the Incidence of Zoonotic Cutaneous Leishmaniasis in Central Tunisia

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    Old world cutaneous leishmaniasis is a vector-borne disease occurring in rural areas of developing countries. The main reservoirs are the rodents Psammomys obesus and Meriones shawi. Zoonotic Leishmania transmission cycle is maintained in the burrows of rodents where the sand fly Phlebotomus papatasi finds the ideal environment and source of blood meals. In the present study we showed seasonality of the incidence of disease during the same cycle with an inter-epidemic period ranging from 4 to 7 years. We evaluated the impact of climate variables (rainfall, humidity and temperature) on the incidence of zoonotic cutaneous leishmaniais in central Tunisia. We confirmed that the risk of disease is mainly influenced by the humidity related to the months of July to September during the same season and mean rainfall lagged by 12 to 14 months

    Microplastics in surface waters of the Gulf of Gabes, southern Mediterranean sea : distribution, composition and influence of hydrodynamics

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    The Mediterranean Sea has been described as one of the most affected areas by marine litter in the world. Although microplastics and their effects have been investigated in this area, most of the currently available studies have been limited to the northwestern part of the basin. This study constitutes a first attempt to determine the abundance, characteristics and composition of microplastics in near surface waters of the Gulf of Gabes (southern Mediterranean Sea, Tunisia). Samples were collected using a 200 mu m-mesh size trawl net along two transects. The study revealed an average concentration of 63,739 items/km(2) where fragments and films were the most frequent microplastics. Polyethylene, reformulated polyethylene and polypropylene were the most abundant plastics identified among the samples (86-100%). The influence of hydrodynamics on microplastics in the Gulf of Gabes was investigated through the use of a Lagrangian tracking model to simulate the dispersion of particles in water. Modelling results seem to be in agreement with the reported distribution and characteristics of microplastics in this area

    Analysis of the Genomics and Mouse Virulence of an Emergent Clone of Streptococcus dysgalactiae Subspecies equisimilis

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    International audienceStreptococcus dysgalactiae subsp. equisimilis is a bacterial pathogen that is increasingly recognized as a cause of severe human infections. Much less is known about the genomics and infection pathogenesis of S. dysgalactiae subsp. equisimilis strains compared to the closely related bacterium Streptococcus pyogenes. To address these knowledge deficits, we sequenced to closure the genomes of seven S. dysgalactiae subsp. equisimilis human isolates, including six that were emm type stG62647. Recently, for unknown reasons, strains of this emm type have emerged and caused an increasing number of severe human infections in several countries. The genomes of these seven strains vary between 2.15 and 2.21 Mbp. The core chromosomes of these six S. dysgalactiae subsp. equisimilis stG62647 strains are closely related, differing on average by only 495 single-nucleotide polymorphisms, consistent with a recent descent from a common progenitor. The largest source of genetic diversity among these seven isolates is differences in putative mobile genetic elements, both chromosomal and extrachromosomal. Consistent with the epidemiological observations of increased frequency and severity of infections, both stG62647 strains studied were significantly more virulent than a strain of emm type stC74a in a mouse model of necrotizing myositis, as assessed by bacterial CFU burden, lesion size, and survival curves. Taken together, our genomic and pathogenesis data show the strains of emm type stG62647 we studied are closely genetically related and have enhanced virulence in a mouse model of severe invasive disease. Our findings underscore the need for expanded study of the genomics and molecular pathogenesis of S. dysgalactiae subsp. equisimilis strains causing human infections. IMPORTANCE Our studies addressed a critical knowledge gap in understanding the genomics and virulence of the bacterial pathogen Streptococcus dysgalactiae subsp. equisimilis. S. dysgalactiae subsp. equisimilis strains are responsible for a recent increase in severe human infections in some countries. We determined that certain S. dysgalactiae subsp. equisimilis strains are genetically descended from a common ancestor and that these strains can cause severe infections in a mouse model of necrotizing myositis. Our findings highlight the need for expanded studies on the genomics and pathogenic mechanisms of this understudied subspecies of the Streptococcus family

    Genetic and mutational heterogeneity of autosomal recessive chronic granulomatous disease in Tunisia

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    International audienceNADPH oxidase, a multi-subunit protein consisting of cytosolic components and the membrane-bound heterodimer, plays an instrumental role in host defence mechanisms of phagocytes. Genetic deficiency of the enzymatic complex results in an inherited disorder, chronic granulomatous disease (CGD), which is characterized by an impaired phagocyte microbicidal activity. X-Linked (XL) CGD results from a mutation in the CYBB gene encoding the gp91phox subunit, while autosomal recessive (AR) CGD is associated with mutations in one of the NCF1, NCF2 and CYBA genes that encode the p47phox, p67phox and p22phox subunits, respectively. In the study reported here, we investigated genetic defects underlying CGD in 15 Tunisian patients from 14 unrelated families. Haplotype analyses and homozygosity mapping with microsatellite markers around known CGD genes assigned the genetic defect to NCF1 in four patients, to NCF2 in four patients and to CYBA in two patients. However, one family with two CGD patients seemed not to link the genetic defect to any known AR-CGD genes. Mutation screening identified two novel mutations in NCF2 and CYBA in addition to the recurrent mutation, Delta GT, in NCF1 and a splice site mutation previously reported in a North African patient. Our results revealed the genetic and mutational heterogeneity of the AR recessive form of CGD in Tunisia

    Patients' preferences of cutaneous leishmaniasis treatment outcomes: Findings from an international qualitative study

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    Background: Cutaneous leishmaniasis (CL) is a disease that often affects exposed skin areas and may heal leaving lifelong scars. Patients’ expectations from treatment are rarely considered in drug development for CL. An initiative aiming to address shortcomings in clinical trial design and conduct for CL treatments involving the researchers’ community is on-going. This manuscript presents patient-preferred outcomes for CL and an assessment on how to consider these in the conduct of future trials. Methodology/Principal findings: We report preferred treatment outcomes by 74 patients with confirmed CL in endemic regions of Brazil, Burkina Faso, Colombia, Iran, Morocco, Peru and Tunisia during individual in-depth interviews. Beyond outcomes customarily considered in trials (such as lesion appearance and adverse events), patients talked about a large number of outcomes related to quality of life, such as pain, scar formation, and others affecting their work and daily activities. They also reported fears around getting rid of the parasite, disease recurrence, and possible sequelae. Conclusions/Significance: The study results provide a rich insight into important outcomes for CL treatments, as well as related topics, from the perspective of a diverse patient population. Among the outcomes identified, we argue that those related to quality of life as well as recurrence should be included to a greater extent for assessment in clinical trials, and discuss the suitability of measurement instruments such as the Dermatology Quality of Life Index (DLQI). Interviews also point out the potential need to address concerns related to parasitological cure or scar formation, such as social stigmatization and disability. In addition, patients should be given information in order to clarify reported misconceptions. This study therefore suggests a methodology for consulting CL patients on outcomes as elements of clinical trial design, and how to incorporate these outcomes in trials. It also discusses how reported outcomes could be addressed in clinical care.</br

    Mass variation in the Mediterranean Sea from GRACE and its validation by altimetry, steric and hydrologic fields

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    The seasonal seawater mass variation in the Mediterranean Sea is estimated between April 2002 and July 2004 from GRACE and altimetry data and from hydrologic and oceanographic models. A smoothed spatial averaging kernel is applied to each field, in order to obtain comparable basin averages. The GRACE seawater mass corrected for the leakage of continental hydrology and the filtered steric?corrected altimeter sea level have similar annual amplitude and phase. To restore the magnitude of the GRACE?derived water mass signal we apply a scaling factor to the smoothed annual amplitude. The estimated scaled mass signal has an annual amplitude of 52 ± 17 mm peaking in November. We combine the seawater mass variation with the Mediterranean freshwater deficit and obtain a net flow at the Strait of Gibraltar with annual amplitude of 60 ± 25 mm/month (0.06 Sv) and maximum in September.Earth Observation and Space SystemsAerospace Engineerin

    An international qualitative study exploring patients’ experiences of cutaneous leishmaniasis: study set-up and protocol

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    Lack of investments in drug development, lack of standardisation of clinical trials and the complexity of disease presentations contribute to the current lack of effective, safe and adapted treatments for cutaneous leishmaniasis (CL). One aspect concerns outcomes affecting patients' quality of life (QoL): these are hardly assessed in trials, despite potential functional and/or aesthetic impairment caused by CL, which typically affects disadvantaged and vulnerable people living in rural areas. Here, we describe the approach used to bring perspectives of patients with CL into designing and assessing treatments.This international qualitative study uses interviews with patients to explore their experiences with CL to (1) elicit outcomes and eligibility criteria for clinical trials important to them and (2) to better understand their needs and views about the disease and their requirements and expectations from treatment. Here, we describe the set-up of this collaborative study and the protocol. Data collection is ongoing.The protocol includes study design, preparation, conduct and analysis of individual interviews with approximately 80 patients in seven countries (Burkina Faso, Brazil, two sites in Colombia, Iran, Morocco, Peru and Tunisia) where CL is prevalent. Principal investigators and sites were selected through an open call, and two workshops were organised for protocol development and training in conduct and analysis of qualitative health research. Patient recruitment aims at covering a maximum variation of experiences. Transcripts will be analysed to identify outcomes and eligibility criteria as well as further topics that are expected to emerge from the interviews, such as direct and indirect costs related to CL, its psychological impact, preferred modes of drug administration and traditional treatments.The study received ethical approval by the responsible committees of each of the participating institutions. Findings will be disseminated through publication in peer-reviewed journals, scientific meetings and to participants and their communities
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