Identification of a novel frameshift mutation in the DFNB31/WHRN gene in a Tunisian consanguineous family with hereditary non-syndromic recessive hearing loss

Approximately 80% of hereditary hearing loss is non-syndromic. Non-syndromic deafness is the most genetically heterogeneous trait. The most common and severe form of hereditary hearing impairment is autosomal recessive non-syndromic hearing loss (ARNSHL), accounting for approximately 80% of cases of genetic deafness. To date, 22 genes implicated in ARNSHL have been identified. Recently a gene, DFNB31/WHRN, which encodes a putative PDZ scaffold protein called whirlin, was found to be responsible for the ARNSHL DFNB31. We found evidence for linkage to the DFNB31locus in a consanguineous Tunisian family segregating congenital profound ARNSHL. Mutation screening of DFNB31/WHRNrevealed four nonpathogenic sequence variants and a novel frameshift mutation [c.2423delG] + [c.2423delG] that changed the reading frame and induced a novel stop codon at amino acid 818 ([p.Gly808AspfsX11] + [p.Gly808AspfsX11]). To determine the contribution of the DFNB31locus in the childhood deafness, we performed linkage analysis in 62 unrelated informative families affected with ARNSHL. No linkage was found to this locus. From this study, we concluded that DFNB31/WHRN is most likely to be a rare cause of ARNSHL in the Tunisian population.     

Propolis attenuates cobalt induced-nephrotoxicity in adult rats and their progeny

The aim of this study was to evaluate the biochemical changes in cobalt-exposed rats and to investigate the potential role of Tunisian propolis against the cobalt-induced renal damages. Twenty-four pregnant Wistar rats were divided into four groups and were treated as follows: group 1 (control) received distilled water; group 2 received 350 ppm of CoCl₂ in drinking water; group 3 received 350 ppm CoCl₂ in drinking water and a propolis-supplemented diet (1 g/100 g of diet); group 4 received a propolis-supplemented diet (1 g/100 g of diet) without cobalt. In the cobalt group, a significant decrease in body, absolute and relative weights was noted when compared to controls. The administration of cobalt to pregnant rats from the 14th day of pregnancy until day 14 after delivery resulted in an increased level of renal malondialdehyde, a decreased renal content of glutathione and antioxidant enzyme activities such as superoxide dismutase, catalase and glutathione peroxidase in lactating rats and their pups. A statistically significant increase in plasma urea and creatinine serum levels was seen in treated female rats and their pups. Histopathologically, the cobalt-administration induced degenerative changes in the kidney of lactating rats and their pups. When compared with cobalt-treated rats, those receiving the propolis supplementation (along with cobalt-treatment) had lower malondialdehyde levels, higher antioxidant activities and the cobalt-related histopathological changes in the kidneys were at lower severity.Our results suggested that the propolis might be a potential candidate agent against cobalt-induced nephrotoxicity in adult and juvenile rats when administered to female rats during the late pregnancy and the early postnatal period.     

Design of a chattering-free integral terminal sliding mode approach for DFIG-based wind energy systems

This article proposes a Fuzzy Second Order Integral Terminal Sliding Mode (FSOITSM) control approach for DFIG-based wind turbines subject to grid faults and parameter variations. Since traditional terminal sliding mode control (SMC) suffers from singularity, a novel integral terminal sliding manifold is proposed to eliminate chattering and improve the wind turbine's performance in the presence of faults and disturbances. A fuzzy system is proposed to auto-tune the controllers' gains and ensures the invariance of the sliding surfaces even under heavy uncertainties, thus further improving the reliability and performance of the proposed controller. The performance of the proposed approach was assessed under various operating conditions. A comparison analysis with a standard SMC approach as well as the state of the art in voltage sag mitigation was also carried over. Reliability, robustness, and power availability under faulty grid conditions are among the main features of the proposed approach. In addition, the proposed approach exhibited chattering free dynamics and enabled the finite time convergence of the sliding manifold and overcame the singularity problem associated with standard TSMC.     

Highly Discriminatory Variable-Number Tandem-Repeat Markers for Genotyping of Trichophyton interdigitale Strains

Trichophyton interdigitale is the second most frequent cause of superficial fungal infections of various parts of the human body. Studying the population structure and genotype differentiation of T. interdigitale strains may lead to significant improvements in clinical practice. The present study aimed to develop and select suitable variable-number tandem-repeat (VNTR) markers for 92 clinical strains of T. interdigitale. On the basis of an analysis of four VNTR markers, four to eight distinct alleles were detected for each marker. The marker with the highest discriminatory power had eight alleles and a D value of 0.802. The combination of all four markers yielded a D value of 0.969 with 29 distinct multilocus genotypes. VNTR typing revealed the genetic diversity of the strains, identifying three populations according to their colonization sites. A correlation between phenotypic characteristics and multilocus genotypes was observed. Seven patients harbored T. interdigitale strains with different genotypes. Typing of clinical T. interdigitale samples by VNTR markers displayed excellent discriminatory power and 100% reproducibility.     

Bone mineral density in healthy Tunisian women

Interpretation of densitometric results requires a comparison with reference bone mineral density (BMD) values of normal age and sex-matched persons. Thus the aim of this study was to determine these values for healthy Tunisian women, to estimate the prevalence of osteoporosis and to compare our findings with other populations. A cross-sectional study of 1378 Tunisian women aged between 20 and 96 years was carried out using DXA (GE-Lunar Prodigy). Subjects with suspected conditions affecting bone metabolism were excluded. Measurements were taken at the lumbar spine and femoral neck. These values were expressed at T-scores, with reference to the mean BMD values of the group aged 20–40 years. The peak bone mass, estimated in this age group was 1.174 + 0.127 g/cm² at the lumbar spine and 1.016 ± 0.118 g/cm² at the femoral site. It was attained respectively within the age of 25 years and 36 years. For both sites, the expected decline in BMD was shown when the successive age groups [40–49 years] and [50–59 years] were compared. Bone loss was rapid during the first 5 years after menopause. Thereafter BMD declined slowly but continually. The prevalence of osteoporosis in the women over 50 years of age, taking account of peak bone mass observed in our cohort, was 23.3% at the spine and 17.3% at the femoral neck with a combined prevalence of 23.4%. These rates attained respectively 30.4%, 11.8% and 32.9% when we considered the Italian values, which demonstrate the variability of osteodensitometric depending to the reference population adopted.     

Hepatotoxicity induced by gibberellic acid in adult rats and their progeny

Gibberellic acid (GA₃), a plant growth regulator, was largely used in agriculture of many countries including Tunisia. However, its potential hazardous effects on human health were relatively unexplored. The purpose of this study was to investigate the effects of GA₃ on hepatic function in female rats and their pups. Animals were given daily 200 ppm GA₃ in drinking water from the 14th day of pregnancy until day 14 after delivery. It was found that GA₃ induced liver damages as evidenced by the elevation of plasma aminotransferases (ALT, AST), lactate dehydrogenase activities, bilirubin and albumin levels. Hepatotoxicity was objectified by the significant increase of malondialdehyde (MDA) level and a decrease of antioxidant enzyme activities such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione content in liver of suckling pups and their mothers. Impairment of hepatic function corresponded histologically. We have observed blood vessels congestion and leucocytes infiltration, which were more pronounced in hepatocytes of dams than those of suckling pups.Results of this current study suggest that exposure rats to GA₃ induces hepatotoxicity and histopathological changes in liver of female rats and their progeny.     

Cholangitis revealing an intrahepatic Osler's disease

Osler Weber Rendu Disease is an hereditary haemorrhagic télangectasia habitually revealed by reccurent bleeding (epistaxis). Hepatic involvement in Osler disease is found in 8 to 31%, manifested by cholestasis. We report an original observation of a cholangitis revealing Osler disease.