Paraphenylenediamine Poisoning in Tunisia: A Case Report

Paraphenylenediamine (PPD) represents the main active substance in the color of hair dyes. In Tunisia, PPD poisoning is very common, especially in rural areas where the consequences linked to this toxic substance are still unknown. In this paper, we report a case of PPD poisoning and confirm the diagnosis by a qualitative method of analysis. We discuss the clinical manifestations and study the kinetics of biological parameters during the monitoring of the poisoning. The main complication was renal failure and the treatment was basically symptomatic

Effect of γ-radiation on free radicals formation, structural changesand functional properties of wheat starch

Wheat starch was treated by different γ-radiation doses (3, 5, 10, 20, 35 and 50 kGy). The effects of γ-radiation on structural, thermal, physicochemical, morphological and rheological properties of wheat starch were studied. The presence of free radicals after γ-radiation treatment, which number decreased with time was confirmed. Structural analysis revealed decreases in the intensities of the O–H and C–H stretches and glycosidic linkages indicating the depolymerization of amylose and probably amy-lopectin into shorter chain molecules, but showed that γ-radiation treatment did not affect the crystalline structure. Differential scanning calorimetric (DSC) thermograms showed the absence of significant differences in the gelatinization temperatures, as well as the corresponding transition enthalpies since the DSC parameters are related to the crystalline ordering within the granules. Apparent amylose content decreased linearly with increasing irradiation dose leading to an increase in water solubility index. Anincrease in the swelling power was observed after irradiation treatment until 20 kGy, followed by a rapiddecrease at higher doses. Microscopic observations showed that the effect of γ-radiation was more visible on starch pastes than on starch granules. Rheological properties of the starch pastes decreased within creasing irradiation dose as a result of glycosidic bond cleavage

Functional characterization of Penicillium occitanis Pol6 and Penicillium funiculosum GH11 xylanases

Xylanases are hemicellulolytic enzymes, which are responsible for the degradation of heteroxylans constituting the lignocellulosic plant cell wall. Xylanases from the GH11 family are considered as true xylanases because of their high substrate specificity. In order to study in depth a crucial difference in the thumb region between two closely related xylanases from Penicillium in terms of kinetic parameters and inhibition sensitivity, the GH11 xylanases from Penicillium occitanis Pol6 (PoXyn3) and from Penicillium funiculosum (PfXynC) were heterologously expressed in Pichia pastoris. The PoXyn3 and PfXynC cDNAs encoding mature xylanases were cloned into pGAPZ alpha A vectors and integrated into the genome of P. pastoris X-33 under the control of the glyceraldehyde 3-phosphate dehydrogenase constitutive promoter. PfXynC was expressed as a His-tagged recombinant protein and purified from the supernatant homogeneity by a one-step purification protocol using immobilized metal affinity chromatography. The recombinant PoXyn3 was purified using a single anion-exchange chromatography. The purified recombinant enzymes were optimally active at 45 degrees C and pH 4.0 for PoXyn3 and 40 degrees C and pH 3.0 for PfXynC. The measured kinetic parameters (k(cat) and V-max) showed that PfXynC was five times more active than PoXyn3 irrespective of the substrate whereas the apparent affinity (K-m) was similar. The recombinant enzymes showed distinct sensitivity to the Triticum aestivum xylanase inhibitor TAXI-I