A catalogue of Clostridium thermocellum endoglucanase, β-glucosidase and xylanase genes cloned in Escherichia coli

Abstract Two independent collections of clones containing Clostridium thermocellum genes involved in cellulose have been previously obtained at IAPGR, Cambridge, and at the Pasteur Institute, Paris. The two collections were compared for cross-hybridization, restriction maps and enzyme phenotypes. Truly distinct genes were one β-glucosidase gene, two xylanase genes, and fifteen endogluconase genes. Two of the cloned fragments contained extraneous DNA which was absent from their respective counterparts isolated in the other collection. The dicrepancies resulted from in vivo rearrangements which had occurred in either of the C. thermocellum NCIB 10682 stocks used to generate the two gene banks.     

Lipotropha dorci n. sp. [Neogregarinida], parasite des larves deDorcus parallelipipedus L. [Coleopt. scarab.]

Résumé Des larves deDorcus parallelipipedus L. provenant de Saint-Hilaire-de-Brethmas (Gard) dans la région méditerranéenne de France et récoltées dans des troncs décomposés de chataigniers, se sont révélées intensément parasitées par des Grégarines appartenant à l'ordre desNeogregarinida. Nous étudions leur localisation dans le tissu adipeux, leur cycle, l'action pathogène sur l'h?te et discutons leur place systématique.

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Summary Lipotropha dorci n. sp. (Neogregarinida) is a parasite developing inDorcus parallelepipedus. The parasite is situated only in the fat body which can be destroyed completely by its activity. The life cycle ofLipotropha includes only one type of schizogony with 3–4 μ long merozo?ts, the spherical uninucleate gametocytes are gathered in pairs and form 23 μ long gametokysts. These give rise to 11 to 12 μ long sporocysts with a thick, non ornamented envelope, gathered round rests of cytoplasma. The size of these different stages enables to distinguishLipotropha dorci from the already described species:Lipotropha macrospora Keilin andLipotropha microspora Keilin.

     

Anomalies des autosomes et infertilité masculine

Spermatogenesis impairment is frequently associated with autosomal rearrangements. A meiotic study was performed on testicular biopsies of men ascertained through primary fertility and found to be heterozygous for reciprocal translocation, Robertsonian translocations, inversions and extra chromosomes. Pairing failure at meiosis as well as intimate associations between rearranged autosomes and the XY bivalent have been discussed as a cause of gametogenic arrest.     

Ferritin conjugates as specific magnetic labels. Implications for cell separation

Concanavalin A coupled to the naturally occurring iron storage protein ferritin is used to label rat erythrocytes and increase the cells' magnetic susceptibility. Labeled cells are introduced into a chamber containing spherical iron particles and the chamber is placed in a uniform 5.2 kG (gauss) magnetic field. The trajectory of cells in the inhomogeneous magnetic field around the iron particles and the polar distributions of cells bound to the iron particles compare well with the theoretical predictions for high gradient magnetic systems. On the basis of these findings we suggest that ferritin conjugated ligands can be used for selective magnetic separation of labeled cells.     

Colorimetric determination of N-hydroxylated metabolites in microsomal studies

A colorimetric method is described which can be used for the routine determination of primary and secondary N-hydroxylamino compounds in drug metabolism studies using microsomal preparations. The assay is carried out on the supernatant obtained after protein precipitation of the incubation mixture. The method is based on the reduction of ferric ion by the hydroxylamino moiety with the resulting ferrous ion being quantitated by coupling with 2,4,6-tripyridyl-s-triazine to form a purple color with a maximum absorbance at 595 nm. The method is specific to primary and secondary hydroxylamino compounds and calibration curves can be obtained in the range of concentrations of 1 to 20 μg/ml. Hydroxamic acid, amido, amino, phenolic, nitro, nitroso, oxime, nitrone, aldehyde, and ketone compounds do not produce any color reaction when analyzed by the same method. The method is simple, rapid, and many samples can be analyzed in a short period of time.     

French recommendations for the management of systemic necrotizing vasculitides (polyarteritis nodosa and ANCA-associated vasculitides)

Systemic necrotizing vasculitis comprises a group of diseases resembling polyarteritis nodosa and anti-neutrophil cytoplasmic antibody-associated vasculitis (ANCA): granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, and microscopic polyangiitis. The definitive diagnosis is made in cooperation with a reference center for autoimmune diseases and rare systemic diseases or a competency center. The management goals are: to obtain remission and, in the long term, healing; to reduce the risk of relapses; to limit and reduce the sequelae linked to the disease; to limit the side effects and the sequelae linked to the treatments; to improve or at least maintain the best possible quality of life; and to maintain socio-professional integration and/or allow a rapid return to school and/or professional activity. Information and therapeutic education of the patients and those around them are an integral part of the care. All health professionals and patients should be informed of the existence of patient associations. The treatment of vasculitis is based on variable combinations of glucocorticoids and immunosuppressants, chosen and adapted according to the disease concerned, the severity and/or extent of the disease, and the underlying factors (age, kidney function, etc.). Follow-up clinical and paraclinical examinations must be carried out regularly to clarify the progression of the disease, detect and manage treatment failures and possible relapses early on, and limit sequelae and complications (early then late) related to the disease or treatment. A distinction is made between the induction therapy, lasting approximately 3–6 months and aimed at putting the disease into remission, and the maintenance treatment, lasting 12–48 months, or even longer. The role of the increase or testing positive again for ANCA as a predictor of a relapse, which has long been controversial, now seems to have greater consensus: Anti-myeloperoxidase ANCAs are less often associated with a relapse of vasculitis than anti-PR3 ANCA.

     

3D strain map of axially loaded mouse tibia: a numerical analysis validated by experimental measurements

A combined experimental/numerical study was performed to calculate the 3D octahedral shear strain map in a mouse tibia loaded axially. This study is motivated by the fact that the bone remodelling analysis, in this in vivo mouse model should be performed at the zone of highest mechanical stimulus to maximise the measured effects. Accordingly, it is proposed that quantification of bone remodelling should be performed at the tibial crest and at the distal diaphysis. The numerical model could also be used to furnish a more subtle analysis as a precise correlation between local strain and local biological response can be obtained with the experimentally validated numerical model.     

Pulsed magnetohydrodynamic blood flow in a rigid vessel under physiological pressure gradient

Blood flow in a steady magnetic field has been of great interest over recent years. Many researchers have examined the effects of magnetic fields on velocity profiles and arterial pressure, and major studies have focused on steady or sinusoidal flows. In this paper, we present a solution for pulsed magnetohydrodynamic blood flow with a somewhat realistic physiological pressure wave obtained using a Windkessel lumped model. A pressure gradient is derived along a rigid vessel placed at the output of a compliant module which receives the ventricle outflow. Then, velocity profile and flow rate expressions are derived in the rigid vessel in the presence of a steady transverse magnetic field. As expected, results showed flow retardation and flattening. The adaptability of our solution approach allowed a comparison with previously addressed flow cases and calculations presented a good coherence with those well established solutions.     

Biomechanical evaluation of porous biodegradable scaffolds for revision knee arthroplasty

Tibial bone defect is a critical problem for revision knee arthroplasty. Instead of using metallic spacer or cement, biodegradable scaffolds could be an alternative solution. A numerical model of a revision knee arthroplasty was thus developed to estimate the mechanical resistance of the scaffold in this demanding situation. The tibia, scaffold, and prosthesis were represented by simplified parameterised geometries. The maximal gait cycle force was applied asymmetrically to simulate a critical loading. Several parameters were analysed: 1) inter-individual variability, 2) cortical bone stiffness, 3) cortical bone thickness, 4) prosthesis fixation quality, and 5) scaffold thickness. The calculated scaffold strain was compared to its experimental ultimate strain. Among the tested parameters, failure was only predicted with scaffold thickness below 5 mm. This study suggests that biodegradable bone scaffolds could be used to fill bone defects in revision knee arthroplasty, but scaffold size seems to be the limiting factor.