Search

Soumaya Ferchichi,1 Hamdi Trabelsi,1 Inès Azzouz,1 Amel Hanini,2 Ahmed Rejeb,3 Olfa Tebourbi,1 Mohsen Sakly,1 Hafedh Abdelmelek1 1Laboratory of Integrative Physiology, Faculty Of Sciences of Bizerte, 2Laboratory of Vascular Pathology, Carthage University, Carthage 3Laboratory of Pathological Anatomy, National School of Veterinary Medicine of Sidi Thabet, Manouba Univeristy, Manouba, Tunisia Abstract: The purpose of our study was the evaluation of toxicological effects of silica-coated gold nanoparticles (GNPs) and static magnetic fields (SMFs; 128 mT) exposure in rat lungs. Animals received a single injection of GNPs (1,100 µg/kg, 100 nm, intraperitoneally) and were exposed to SMFs, over 14 days (1 h/day). Results showed that GNPs treatment induced a hyperplasia of bronchus-associated lymphoid tissue. Fluorescence microscopy images showed that red fluorescence signal was detected in rat lungs after 2 weeks from the single injection of GNPs. Oxidative response study showed that GNPs exposure increased malondialdehyde level and decreased CuZn-superoxide dismutase, catalase, and glutathione peroxidase activities in rat lungs. Furthermore, the histopathological study showed that combined effects of GNPs and SMFs led to more tissular damages in rat lungs in comparison with GNPs-treated rats. Interestingly, intensity of red fluorescence signal was enhanced after exposure to SMFs indicating a higher accumulation of GNPs in rat lungs under magnetic environment. Moreover, rats coexposed to GNPs and SMFs showed an increased malondialdehyde level, a fall of CuZn-superoxide dismutase, catalase, and glutathione peroxidase activities in comparison with GNPs-treated group. Hence, SMFs exposure increased the accumulation of GNPs in rat lungs and led to more toxic effects of these nanocomplexes. Keywords: malondialdehyde, catalase, superoxide dismutase, glutathione peroxidase, bronchus-associated lymphoid tissue, nanotoxicity, histopathological study

Inès Azzouz, Hamdi Trabelsi, Amel Hanini, Soumaya Ferchichi, Olfa Tebourbi, Mohsen Sakly, Hafedh AbdelmelekLaboratory of Integrative Physiology, Faculty of Sciences of Bizerte, Carthage University, TunisiaAbstract: The aim of the present study was to investigate the interaction of zinc chloride (3 mg/kg, intraperitoneally [ip]) in rat liver in terms of the biosynthesis of nanoparticles. Zinc treatment increased zinc content in rat liver. Analysis of fluorescence revealed the presence of red fluorescence in the liver following zinc treatment. Interestingly, the co-exposure to zinc (3 mg/kg, ip) and selenium (0.20 mg/L, per os [by mouth]) led to a higher intensity of red fluorescence compared to zinc-treated rats. In addition, X-ray diffraction measurements carried out on liver fractions of zinc-treated rats point to the biosynthesis of zinc sulfide and/or selenide nanocomplexes at nearly 51.60 nm in size. Moreover, co-exposure led to nanocomplexes of about 72.60 nm in size. The interaction of zinc with other mineral elements (S, Se) generates several nanocomplexes, such as ZnS and/or ZnSe. The nanocomplex ZnX could interact directly with enzyme activity or indirectly by the disruption of mineral elements' bioavailability in cells. Subacute zinc or selenium treatment decreased malondialdehyde levels, indicating a drop in lipid peroxidation. In addition, antioxidant enzyme assays showed that treatment with zinc or co-treatment with zinc and selenium increased the activities of glutathione peroxidase, catalase, and superoxide dismutase. Consequently, zinc complexation with sulfur and/or selenium at nanoscale level could enhance antioxidative responses, which is correlated to the ratio of number of ZnX nanoparticles (X=sulfur or X=selenium) to malondialdehyde level in rat liver.Keywords: nanocomplexes biosynthesis, antioxidative responses, X-ray diffraction, fluorescence microscopy, liver

Hamdi Trabelsi, Inès Azzouz, Soumaya Ferchichi, Olfa Tebourbi, Mohsen Sakly, Hafedh Abdelmelek Laboratory of Integrative Physiology, Faculty of Sciences of Bizerte, Carthage University, Jarzouna, Tunisia Abstract: The aim of this study was to investigate the interaction of cadmium chloride with mineral elements in rat nephrocytes in terms of the biosynthesis of nanocomplexes. The results show that selenium supplementation enhanced cadmium accumulation in kidneys. Analysis of the fluorescence revealed an increase in red fluorescence in the kidneys of rats co-exposed to cadmium and selenium. Interestingly, X-ray diffraction measurements carried out on kidney fractions of co-exposed rats point to the biosynthesis of cadmium selenide and/or sulfide nanoparticles (about 62 nm in size). Oxidative stress assays showed the ability of selenium to reduce lipid peroxidation and to restore glutathione peroxidase and superoxide dismutase activity in kidneys. Hence, cadmium complexation with selenium and sulfur at a nanoscale level could reduce oxidative stress induced by cadmium in kidneys. Keywords: nanoparticles, detoxification, oxidative stress, X-ray diffraction, fluorescence microscopy, kidneys

Hamdi Trabelsi, Inès Azzouz, Mohsen Sakly, Hafedh Abdelmelek Laboratory of Physiologie Intégrée, Faculty of Sciences of Bizerte, Carthage University, Tunisia Abstract: The purpose was to study the toxicity of cadmium (Cd) and to explore its potential to generate nanoparticles during detoxification. In order to demonstrate this, in vivo fluorescence imaging, X-ray diffraction, and flow cytometry were performed. The in vivo imaging showed a fluorescence signal after Cd treatment (CdCl2, 1.50 mg/Kg, intraperitoneally). By contrast, the control-rat fluorescence was negative. The fluorescence was divided into three colors, red, yellow, and green, and probably indicates the presence of quantum dots. X-ray diffraction results revealed the presence of Cd sulfide (CdS) and/or Cd selenide (CdSe) nanoparticles following Cd injection in the liver (6.52 nm) and kidneys (56.30 nm). Interestingly, flow cytometry revealed a heterogeneous size distribution and a homogeneous granularity of synthesized nanoparticles. Using the green fluorescence channel and the red fluorescence channel, a narrow green emission spectrum and a broad red emission spectrum were detected, respectively, by cytometric analysis. Keywords: XRD, in vivo imaging, flow cytometry, quantum dots, cadmium sulfide, cadmium selenide

The aim of our study was to detect free-living Amoebae (FLA) by morphological methods and to identify Acanthamoeba spp. by PCR in the dental unit water lines (DUWL). Materials and methods: it was a prospective study dealing with 196 water samples collected from DUWL (94 samples taken in the early morning before materials flush and patient consultations and 102 samples taken after consultations). At the same time, 39 samples from tap water were realized. Results: 135 (69 %) samples were positives by the morphological study with morphotypical diversity. The predominant morphotype was the monopodial (39.2 %). 18 strains of Acanthamoeba spp. were detected in DUW (13.3 %) and three strains in tap water (10 %). The amplification of 18S rDNA gene of these strains of Acanthamoeba spp. was positive for all samples. Conclusion: the FLA and Acanthamoeba were isolated both in tap water and in dental unit. The amoeba pathogenicity has not been demonstrated after oral or dental contamination; but the presence of intracellular and pathogenic bacteria in the amoeba could be a source of microbiological risks for patients in case of deep dental care or immunodepression. The improvement of this dental unit was necessary by putting a filter of 0.2 microns porosity before the arrival of the water in hand-pieces allowing the limitation of FLA passage.

The current paper presents an investigation on the tensile strength of unsaturated clay, and a discussion about the significant differences between the behaviours of compacted soils and those of the completely remoulded soils. The adapted experimental device based on the shear box for the measurement of the tensile strength is also presented. In the tensile tests, stress-strain characteristics are measured using high precision transducers and electronic data acquisition. The equipment is capable of measuring tensile strengths of soil (about 10 MPa). Moreover, a new model to predict cracks is presented in 3D. This analytical model for the prediction of tensile strength, as a function of suction and porosity, is given.

This paper deals with the problem of the uncertainties interaction in the design parameters of a two-stage gearbox of a wind turbine. The purpose of the dynamic study is to minimize the linear displacements in order to have more stability. The uncertainty consideration using a unique parameter, allowed the identification of the influence of this latter on the dynamic response, in addition to its extreme values. The examination of multivariate parameters investigates the interaction of these parameters. Thus, the gear system dynamic behavior was studied by taking into account the uncertainty with a suggested diagram: uncoupled form to evaluate the impact of each parameter and coupled form based on the progressive interaction of uncertain dynamic parameters using the multivariate uncertainty method. For this purpose, the generalized polynomial chaos approach (GPC) was applied to simulate the dynamic behavior of the wind turbine gearbox. The obtained results were then verified using Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

This study aimed to investigate azole resistance mechanisms in Aspergillus flavus, which involve cyp51A and cyp51B genes. Real-time Reverse Transcriptase qPCR method was applied to determine the overexpression of cyp51A and cyp51B genes for 34 A. flavus isolates. PCR sequencing of these two genes was used to detect the presence of gene mutations. Susceptibility test found sensitivity to voriconazole (VOR) in all strains. 14.7% and 8.8% of isolates were resistant to itraconazole (IT) and posaconazole (POS), respectively, with a cross-resistance in 5.8%. For the double resistant isolates (IT/POS), the expression of cyp51A was up to 17-fold higher. PCR sequencing showed the presence of 2 mutations in cyp51A: a synonymous point mutation (P61P) in eight isolates, which did not affect the structure of CYP51A protein, and another non synonymous mutation (G206L) for only the TN-33 strain (cross IT/POS resistance) causing an amino acid change in the protein sequence. However, we noted in cyp51B the presence of the only non-synonymous mutation (L177G) causing a change in amino acids in the protein sequence for the TN-31 strain, which exhibits IT/POS cross-resistance. A short single intron of 67 bp was identified in the cyp51A gene, whereas three short introns of 54, 53, and 160 bp were identified in the cyp51B gene. According to the models provided by PatchDock software, the presence of non-synonymous mutations did not affect the interaction of CYP51A and CYP51B proteins with antifungals. In our study, the overexpression of the cyp51A and cyp51B genes is the primary mechanism responsible for resistance in A. flavus collection. Nevertheless, other resistance mechanisms can be involved.

Cohesive soil was often submitted to the shrinkage when it is dried. Constrained shrinkage and heterogeneity of the soil in terms of density or porosity and water content conduct to cracks of the fine soil. The unsaturated permeability as a function of suction changes significantly with cracks number and opening. The paper aims to study the flow exchange flow in the unsaturated cracked clay flow, by measurement of the unsaturated permeability using tensiometer and hygrometer sensors in cracked specimens under drying and controlled in an environmental chamber. The instantaneous profile method was used to interpret these tests. Cracks were characterised by Image Analysis which conducted to define some known quantitative parameters as the Cracks Intensity Factor (CIF). Aiming at reproducing the experimental results, the paper presents a model which leads to the prediction of the suction field and the flow rate exchange. This model integrates analytical equations of the unsaturated permeability and water retention property of the cracked soil and also the shrinkage behaviour. A good agreement between numerical and experimental results is highlighted in terms of flow exchange rate. [ABSTRACT FROM AUTHOR]