High-resolution molecular fingerprinting in the 11.6-15 μm range by a quasi-CW difference-frequency-generation laser source

We report an approach for high-resolution spectroscopy using a widely tunable laser emitting in the molecular fingerprint region. The laser is based on difference-frequency generation (DFG) in a nonlinear orientation-patterned GaAs crystal. The signal laser, a CO2 gas laser, is operated in a kHz-pulsed mode while the pump laser, an external-cavity quantum cascade laser, is finely mode-hop-free tuned. The idler radiation covers a spectral range of ∼11.6-15 μm with a laser linewidth of ∼ 2.3 MHz. We showcase the versatility and the potential for molecular fingerprinting of the developed DFG laser source by resolving the absorption features of a mixture of several species in the long-wavelength mid-infrared. Furthermore, exploiting the wide tunability and resolution of the spectrometer, we resolve the broadband absorption spectrum of ethylene (C2H4) over ∼13-14.2 μm and quantify the self-broadening coefficients of some selected spectral lines

Contrasting patterns of hepatitis C virus infection in two regions from Tunisia

International audienceThis report is a population-based study describing the pattern of hepatitis C virus (HCV) infection in two distinct regions in Tunisia. The study included a total of 11,507 individuals sampled in 1996 from both genders, all age groups, urban and rural settings belonging to 2,973 families. HCV infection was assessed by commercial enzyme immunoassay (EIA) and immunoblot assays and detection of HCV RNA by PCR. HCV genotypes and subtypes were determined by sequencing in the 5'-untranslated region (UTR) viral genomic region and the INNO-LiPA HCVII genotyping kit. Genetic relatedness between HCV strains was assessed by sequencing of a portion of the NS5B region. HCV prevalence was significantly higher in the North-Western region than in the Southern one: 1.7% versus 0.2% (P < 10(-3), chi(2)=8,506). There was no difference in positivity according to gender or living in rural or urban settings; the only significant risk factor was advanced age. HCV prevalence among household contacts of HCV positives was not significantly higher than the prevalence in the whole study population. These results indicate a heterogeneity in the geographical distribution of HCV in Tunisia. An increased HCV transmission occurs in the North-Western region with large predominance of genotype 1b (88%) and low contribution of intrafamilial transmission. (c) 2005 Wiley-Liss, Inc

Infections par des virus transmissibles par le sang chez des hémophiles en Tunisie

International audienceIn this work, we proposed to evaluate prevalences of hepatitis B and C viruses and Parvovirus B19 among 70 Tunisian haemophiliacs treated with clotting factors imported from Europe and/or locally produced cryoprecipitate; among them 6 (8.6%) are known HIV positive patients. HBs antigen, anti-HBc antibodies and anti-Parvovirus B19 antibodies were detected in 7.1%, 52.9% and 91.8%, respectively. HCV prevalence, defined as positive ELISA with positive Immunoblot and/or PCR was 50.0%. Prevalences of these viral infections in haemophiliacs are higher than prevalences detected among general population and in the control group of the study. HCV infection is less frequent in haemophiliacs born after 1985, the year of introduction of the inactivation procedures in the production of coagulation factors concentrates; it decreases more considerably after 1994, date of introduction of systematic screening of HCV among blood donors. In contrast, despite the inactivation of the factors concentrates and the systematic screening of the blood donations against HBs antigen, since 1973, the risk of HBV infection contamination remains high in the Tunisian haemophiliacs. The introduction in 1995 of hepatitis B vaccination in the national schedule of new-born vaccination may resolve in the future the problem of HBV infection in haemophiliacs and in the other categories of the Tunisian population.Dans ce travail, nous nous sommes proposés d'évaluer les prévalences des infections par les virus des hépatites B et C et le parvovirus B19 chez 70 hémophiles tunisiens traités avec les facteurs de coagulation importés d'Europe et/ou le cryoprécipité fabriqué localement ; parmi eux six patients (8,6 %) sont connus VIH positifs. L'antigène HBs, les anticorps anti-HBc et les anticorps anti-Parvovirus B19 ont été retrouvés chez 7,1, 52,9 et 91,8 % des patients, respectivement. La prévalence de l'infection par le VHC, définie par un test Elisa positif avec Immunoblot et/ou PCR positifs, a été de 50,0 %. Les prévalences de ces infections virales sont plus élevées chez les hémophiles que dans la population générale et la population témoin admise dans ce travail. L'infection à VHC est plus faible chez les sujets hémophiles nés après 1985, date d'introduction des procédés d'inactivation virale dans la fabrication des concentrés de facteurs de coagulation. Elle est encore plus faible chez les patients nés après 1994, date d'introduction du dépistage systémique du VHC chez les donneurs de sang tunisiens. En revanche, malgré l'inactivation des concentrés de facteurs et le dépistage systématique des dons du sang vis-à-vis de l'AgHBs depuis 1973, un risque élevé de contamination par le VHB persiste chez les hémophiles tunisiens. L'introduction depuis 1995 de la vaccination anti-hépatite B dans le calendrier national de vaccination des nouveau-nés devrait prochainement résoudre le problème de l'infection à VHB aussi bien chez les hémophiles que chez d'autres catégories de la population tunisienne

Traumatic isolated perforation of lower oesophagus

One of the rarest cases of non-iatrogenic oesophageal perforation is falling from height. We report a case of a 26 year old man with oesophageal perforation resulting from a fall of 12 meter height. A pneumomediastinum in the absence of a pneumothorax and contrast extravasation from the oesophagus on CT evoked a perforation of the aerodigestive tract. No other injuries were seen. A non-operative management was pursued with good outcomes. Keywords: Oesophageal perforation, Trauma, Pneumomediastinum, High fallin

Hepatitis B genotypes, precore and core promoter mutants circulating in Tunisia

International audienceHepatitis B virus (HBV) is characterized by genetic heterogeneity, including genotypes and mutations. Eight genotypes (A-H) have been identified throughout the world with a characteristic geographical distribution. Previous studies also suggest that the viral genotypes may correlate with differences in clinical features of the infection. Two types of mutations were particularly described, precore and basal promoter mutations; they may play an important role in the clinical outcome of HBV infection. The aim of this study was to investigate the prevalence of HBV genotypes and HBV variants in Tunisia, and their eventual association with severity of liver disease. Using a molecular method, HBV genotypes, precore and basal core promoter mutations were determined in 56 asymptomatic carriers and in 82 patients with histologically verified chronic liver disease and hepatocellular carcinoma (HCC). Three genotypes (D, A, and E) were detected; the prevalence was 80%, 8%, and 9%, respectively. No significant difference was observed for genotype D with clinical status. HBV mutants were detected in 93% of cases, precore mutants were the most prevalent. Basal core promoter mutants were observed in 61% of cases, they were frequently characterized by a double mutation in 1762 and 1764. Co-infection by these two types of mutants was detected in 50% of cases. Genotype D was the most prevalent HBV genotype in Tunisia. High circulation of precore and basal core promoter mutants are common in chronic hepatitis B infection in Tunisia