The Determinants Of World Islamic Banks Efficiency: Empirical Analysis Using A Non Parametric Approach

The purpose of this paper is to analyze the efficiency of Islamic banks operating in different countries, over the period 2006-2009.We applied a non-parametric approach, or a Data Envelopment Analysis (DEA), that utilizes both the constant returns to scale (CRS) and the variable returns to scale (VRS) assumptions to offer measures of the technical and scale efficiency. The outcomes reveal a considerable degree of dispersion of technical efficiency between banks within the sample of the year-to-year basis. To inspect the determinants of efficiency, we apply the panel regression analysis. In fact, we used panel regression analysis in order to explain the variation in the dependent variable (calculated efficiencies) by a set of independent variables, such as banks size, asset quality, management capability, liquidity, sensitivity to markets risks, and capitalization.We find that banks with higher liquidity and a good management capability are more likely to operate at higher levels of technical efficiency. In addition, the results show that size, seem to contribute negatively to the evolution of efficiency scores of Islamic banks operating in the world

Integrative Gene Cloning and Expression System for Streptomyces sp. US 24 and Streptomyces sp. TN 58 Bioactive Molecule Producing Strains

Streptomyces sp. US 24 and Streptomyces sp. TN 58, two strains producing interesting bioactive molecules, were successfully transformed using E. coli ET12567 (pUZ8002), as a conjugal donor, carrying the integrative plasmid pSET152. For the Streptomyces sp. US 24 strain, two copies of this plasmid were tandemly integrated in the chromosome, whereas for Streptomyces sp. TN 58, the integration was in single copy at the attB site. Plasmid pSET152 was inherited every time for all analysed Streptomyces sp. US 24 and Streptomyces sp. TN 58 exconjugants under nonselective conditions. The growth, morphological differentiation, and active molecules production of all studied pSET152 integrated exconjugants were identical to those of wild type strains. Consequently, conjugal transfer using pSET152 integration system is a suitable means of genes transfer and expression for both studied strains. To validate the above gene transfer system, the glucose isomerase gene (xylA) from Streptomyces sp. SK was expressed in strain Streptomyces sp. TN 58. Obtained results indicated that heterologous glucose isomerase could be expressed and folded effectively. Glucose isomerase activity of the constructed TN 58 recombinant strain is of about eighteenfold higher than that of the Streptomyces sp. SK strain. Such results are certainly of importance due to the potential use of improved strains in biotechnological process for the production of high-fructose syrup from starch

Modeling-based optimization approaches for the development of Anti- Agrobacterium tumefaciens activity using Streptomyces sp TN71

A new aerobic bacterium TN71 was isolated from Tunisian Saharan soil and has been selected for its antimicrobial activity against phytopathogenic bacteria. Based on cellular morphology, physiological characterization and phylogenetic analysis, this isolate has been assigned as Streptomyces sp. TN71 strain. In an attempt to increase its anti-Agrobacterium tumefaciens activity, GYM + S (glucose, yeast extract, malt extract and starch) medium was selected out of five different production media and the medium composition was optimized. Plackett-Burman design (PBD) was used to select starch, malt extract and glucose as parameters having significant effects on antibacterial activity and a Box-Behnken design was applied for further optimization. The analysis revealed that the optimum concentrations for anti-A. tumefaciens activity of the tested variables were 19.49 g/L for starch, 5.06 g/L for malt extract and 2.07 g/L for glucose. Several Artificial Neural Networks (ANN): the Multilayer perceptron (MLP) and the Radial basis function (RBF) were also constructed to predict anti-A. tumefaciens activity. The comparison between experimental with predicted outputs from ANN and Response Surface Methodology (RSM) were studied. ANN model presents an improvement of 12.36% in terms of determination coefficients of anti A. tumefaciens activity. To our knowledge, this is the first work reporting the statistical versus artificial intelligence based modeling for optimization of bioactive molecules against phytopathogen

Inhibition of Fungi and Gram-Negative Bacteria by Bacteriocin BacTN635 Produced by Lactobacillus plantarum sp. TN635

The aim of this study was to evaluate 54 lactic acid bacteria (LAB) strains isolated from meat, fermented vegetables and dairy products for their capacity to produce antimicrobial activities against several bacteria and fungi. The strain designed TN635 has been selected for advanced studies. The supernatant culture of this strain inhibits the growth of all tested pathogenic including the four Gram-negative bacteria (Salmonella enterica ATCC43972, Pseudomonas aeruginosa ATCC 49189, Hafnia sp. and Serratia sp.) and the pathogenic fungus Candida tropicalis R2 CIP203. Based on the nucleotide sequence of the 16S rRNA gene of the strain TN635 (1,540 pb accession no FN252881) and the phylogenetic analysis, we propose the assignment of our new isolate bacterium as Lactobacillus plantarum sp. TN635 strain. Its antimicrobial compound was determined as a proteinaceous substance, stable to heat and to treatment with surfactants and organic solvents. Highest antimicrobial activity was found between pH 3 and 11 with an optimum at pH = 7. The BacTN635 was purified to homogeneity by a four-step protocol involving ammonium sulfate precipitation, centrifugal microconcentrators with a 10-kDa membrane cutoff, gel filtration Sephadex G-25, and C18 reverse-phase HPLC. SDS-PAGE analysis of the purified BacTN635, revealed a single band with an estimated molecular mass of approximately 4 kDa. The maximum bacteriocin production (5,000 AU/ml) was recorded after a 16-h incubation in Man, Rogosa, and Sharpe (MRS) medium at 30 °C. The mode of action of the partial purified BacTN635 was identified as bactericidal against Listeria ivanovii BUG 496 and as fungistatic against C. tropicalis R2 CIP203

Bioactive Secondary Metabolites from a New Terrestrial Streptomyces sp. TN262

During our search for Streptomyces spp. as new producers of bioactive secondary metabolites, the ethyl acetate extract of the new terrestrial Streptomyces isolate TN262 delivered eight antimicrobially active compounds. They were identified as 1-acetyl-β-carboline (1), tryptophol (2), cineromycin B (3), 2,3-dihydrocineromycin B (4), cyclo-(tyrosylprolyl) (5), 3-(hydroxyacetyl)-indole (6), brevianamide F (7), and cis-cyclo-(l-prolyl-l-leucyl) (8). Three further metabolites were detected in the unpolar fractions using GC–MS and tentatively assigned as benzophenone (9), N-butyl-benzenesulfonamide (10), and hexanedioic acid-bis-(2-ethylhexyl) ester (11). This last compound is known as plasticizer derivatives, but it has never been described from natural sources. In this article, we describe the identification of the new Streptomyces sp. isolate TN262 using its cultural characteristics, the nucleotide sequence of the corresponding 16S rRNA gene and the phylogenetic analysis, followed by optimization, large-scale fermentation, isolation of the bioactive constituents, and determination of their structures. The biological activity of compounds (2), (3), (4), and those of the unpolar fractions was addressed as well

Hereditary breast cancer in Middle Eastern and North African (MENA) populations: identification of novel, recurrent and founder BRCA1 mutations in the Tunisian population

Germ-line mutations in BRCA1 breast cancer susceptibility gene account for a large proportion of hereditary breast cancer families and show considerable ethnic and geographical variations. The contribution of BRCA1 mutations to hereditary breast cancer has not yet been thoroughly investigated in Middle Eastern and North African populations. In this study, 16 Tunisian high-risk breast cancer families were screened for germline mutations in the entire BRCA1 coding region and exon–intron boundaries using direct sequencing. Six families were found to carry BRCA1 mutations with a prevalence of 37.5%. Four different deleterious mutations were detected. Three truncating mutations were previously described: c.798_799delTT (916 delTT), c.3331_3334delCAAG (3450 delCAAG), c.5266dupC (5382 insC) and one splice site mutation which seems to be specific to the Tunisian population: c.212 + 2insG (IVS5 + 2insG). We also identified 15 variants of unknown clinical significance. The c.798_799delTT mutation occurred at an 18% frequency and was shared by three apparently unrelated families. Analyzing five microsatellite markers in and flanking the BRCA1 locus showed a common haplotype associated with this mutation. This suggests that the c.798_799delTT mutation is a Tunisian founder mutation. Our findings indicate that the Tunisian population has a spectrum of prevalent BRCA1 mutations, some of which appear as recurrent and founding mutations

Leptin and leptin receptor polymorphisms are associated with increased risk and poor prognosis of breast carcinoma

BACKGROUND: Leptin (LEP) has been consistently associated with angiogenesis and tumor growth. Leptin exerts its physiological action through its specific receptor (LEPR). We have investigated whether genetic variations in LEP and LEPR have implications for susceptibility to and prognosis in breast carcinoma. METHODS: We used the polymerase chain reaction and restriction enzyme digestion to characterize the variation of the LEP and LEPR genes in 308 unrelated Tunisian patients with breast carcinoma and 222 healthy control subjects. Associations of the clinicopathologic parameters and these genetic markers with the rates of the breast carcinoma-specific overall survival (OVS) and the disease free survival (DFS) were assessed using univariate and multivariate analyses. RESULTS: A significantly increased risk of breast carcinoma was associated with heterozygous LEP (-2548) GA (OR = 1.45; P = 0.04) and homozygous LEP (-2548) AA (OR = 3.17; P = 0.001) variants. A highly significant association was found between the heterozygous LEPR 223QR genotype (OR = 1.68; P = 0.007) or homozygous LEPR 223RR genotype (OR = 2.26; P = 0.001) and breast carcinoma. Moreover, the presence of the LEP (-2548) A allele showed a significant association with decreased disease-free survival in breast carcinoma patients, and the presence of the LEPR 223R allele showed a significant association with decreased overall survival. CONCLUSION: Our results indicated that the polymorphisms in LEP and LEPR genes are associated with increased breast cancer risk as well as disease progress, supporting our hypothesis for leptin involvement in cancer pathogenesis

Détection d'épistasie dans les études d'association pangénomiques avec des techniques d'apprentissage pour l'identification de cibles thérapeutiques

By offering an unprecedented picture of the human genome, genome-wide association studies (GWAS) have been expected to fully explain the genetic background of complex diseases. So far, the results have been mitigated to say the least. This, among other things, can be partially attributed to the adopted statistical methodology, which does not often take into account interaction between genetic variants, or epistasis. The detection of epistasis through statistical models presents several challenges for which we develop in this thesis a pair of adequate tools. The first tool, epiGWAS, uses causal inference to detect epistatic interactions between a target SNP and the rest of the genome. The second tool, kernelPSI, instead uses kernel methods to model epistasis between nearby single-nucleotide polymorphisms (SNPs). It also leverages post-selection inference to jointly perform SNP-level selection and gene-level significance testing. The developed tools are -- to the best of our knowledge -- the first to extend powerful statistical learning frameworks such as causal inference and nonlinear post-selection inference to GWAS. In addition to the methodological contributions, a special emphasis was placed on biological interpretation to validate our findings in multiple sclerosis and body-mass index variations.En offrant une image sans précédent du génome humain, les études d'association pangénomiques (GWAS) expliqueraient pleinement le contexte génétique des maladies complexes. A ce jour, les résultats ont été pour le moins mitigés. Cela peut être partiellement attribué à la méthodologie statistique adoptée, qui ne prend pas souvent en compte l'interaction entre les variants génétiques, ou l'épistasie. La détection d'épistasie à travers des modèles statistiques présente plusieurs défis pour lesquels nous développons dans cette thèse une paire d'outils adéquats. Le premier outil, epiGWAS, utilise l'inférence causale pour détecter les interactions épistatiques entre un SNP cible et le reste du génome. Le deuxième outil, kernelPSI, utilise à la place des méthodes à noyaux pour modéliser l'épistasie entre plusieurs polymorphismes mononucléotidiques (SNPs) voisins. Il tire également partie de l'inférence post-sélection pour effectuer conjointement une sélection au niveau des SNPs et des tests de signification au niveau des gènes. Les outils développés sont - au meilleur de nos connaissances - les premiers à étendre au domains des GWAS des outils puissants d'apprentissage statistique tels que l'inférence causale et l'inférence post-sélection nonlinéaire. En plus des contributions méthodologiques, un accent particulier a été mis sur l'interprétation biologique pour valider nos résultats dans la sclérose en plaques et les variations d'indice de masse corporelle

Studium niezależności rady nadzorczej a zarządzanie wynikiem finansowym firmy

This study examines the relationship between the independence of the Board of Directors and earnings management for firms of the stock exchange of Paris which have applied the International Accounting Standard of IASB. We have used methods of structural equations and have shown that a high proportion of independent outside directors constrain the leader to use earnings management