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A half-collision process is described within a hemiquantal time dependent model to calculate the absorption line shape. The photodissociation of ICN in a collinear geometry serves as an illustrative example with the ‘‘light’’ CN motion treated quantum mechanically, whereas the ‘‘heavy’’ I–CN motion is treated classically. The emphasis is put on (i) the way to introduce the Wigner distribution which appears to be the equivalent of the classical density matrix, and (ii) the choice of the initial positions and momenta in the sampling of trajectories. The so-obtained converged results compare, within good accuracy, with the full quantal ones. Both conceptually and computationally, the hemiquantal approach appears as an interesting alternative to the full quantum wave packet calculation. [ABSTRACT FROM AUTHOR]

Background: Dyspnea and the decrease in arterial saturation in the upright position in elderly subjects is described as platypnea-orthodeoxia syndrome (POS). POS is secondary to the occurrence of an atrial right-to-left shunt through a patent foramen ovale (PFO). Methods: This French multicentric study reports on 78 patients (mean age 67 +/- 11.3 years) with POS who had transcatheter closure of the PFO; frequently associated diseases were pneumonectomy (n = 36) and an ascending aortic aneurysm (n = 11). In all patients, the diagnosis was confirmed by transthoracic or/and transesophageal echocardiography. Five different closure devices were used: Amplatz (n = 45), Cardioseal (n = 13), Sideris (n = 11), Das Angel Wings (n = 8) and Starflex (n = 1). Closure was successful in 76 patients (97%). Results: Oxygen saturation increased immediately after occlusion from 84.6 +/- 10.7% to 95.1 +/- 6.4% (p < 0.001) and dyspnea improved from grade 2.7 +/- 0.7 to grade 1 +/- 1 (p < 0.001). A small residual shunt was immediately observed in 5 patients (3 with the Cardioseal device, 1 with the Sideris and 1 with the Amplatz) leading to the implantation of a second device in one case (Cardioseal). Two early deaths occurred unrelated to the procedure (one due to sepsis probably related to pneumonectomy, another due to respiratory insufficiency). Other complications were: a small shunt between the aorta and the left atrium, two atrial fibrillations and a left-sided thrombus which disappeared with anticoagulant therapy. At a mean follow-up of 15 +/- 12 months, there were 7 late deaths related to the underlying disease. Conclusion: Percutaneous occlusion of the foramen ovale is safe and gives excellent results thanks to continuing improvement in available devices. This technique enables some patients in an unstable condition to avoid a surgical closure. [ABSTRACT FROM AUTHOR]

Oxidative stress is involved in the aetiology of defective embryo development. Reactive oxygen species (ROS) may originate from embryo metabolism and/or embryo surroundings. Embryo metabolism generates ROS via several enzymatic mechanisms. The relative contribution of each source seems different depending on the species, the stage of development, and the culture conditions. Several exogenous factors and culture conditions can enhance the production of ROS by embryos. ROS can alter most types of cellular molecules, and also induce development block and retardation. Multiple mechanisms of embryo protection against ROS exist, and these have complementary actions. External protection, present in follicular and tubal fluids, mainly comprises non-enzymatic antioxidants such as hypotaurine, taurine and ascorbic acid. Internal protection mainly comprises antioxidant enzymes: superoxide dismutase, glutathione peroxidase and gamma-glutamylcysteine synthetase. Transcripts encoding for these enzymes are present in the oocyte, embryo and oviduct. It may be important that these transcripts are stored during oocyte maturation in order to allow the embryo to acquire the aptitude to develop. It is now common to add antioxidant compounds to culture media. Nevertheless, maintaining the pro-oxidant-antioxidant equilibrium in embryos through such supplementation is a complex problem. Further studies are necessary to limit oxidative stress during embryo culture. [ABSTRACT FROM AUTHOR]

An approach based on the double Lagrange multipliers is developed using the finite element method in order to impose complex periodic or anti-periodic boundary conditions. The magnetostatic equations are solved using the vector or scalar potential formulations. In order to show the possibilities of the proposed approach, an example of application is studied and the results are discussed. [ABSTRACT FROM AUTHOR]

The Mobi-C® cervical disc replacement is a semi-constrained prosthesis with a mobile polyethylene insert situated between two chrome cobalt plates. The insert can slide. Overall the Mobi-C® device has five degrees of freedom. The primary indications are as follows: 1) soft herniated discs leading to cervicobrachial pain refractory to conservative treatment; 2) some cases of hard herniated discs if movement has been documented on intra-operative dynamic bending films; 3) much more rarely in cases of spinal cord compression with myelopathy. Technically, centering of the device is facilitated by the dedicated instrument system. Regarding the results, the clinical efficacy is conventional. Mobility is preserved at a minimum 2-year follow-up in 85.5% of the devices. The main mechanical complications are radiological adjacent syndrome and heterotopic ossification (HO), among which even those of class III permit residual movement. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHAs) form an enlarged family of biopolyesters, which are biocompatible, biodegradable and non-toxic. Polyhydroxyalkanoates biodegradation corresponds to a hydrolysis involving endo- or exo-enzymatic systems in the breaking cleavage of esters bonds. This type of degradation is needed for environmental applications. In the case of therapeutic and biomedical uses, a simple hydrolysis is required. Hydrolytic degradation of PHAs is not evident as shown on poly(3-hydroxyoctanoate) (PHO) and is depending on the structure of the polyester and more particularly on the nature of the side chains. In some cases, blending with others polymers has decreased PHAs crystallinity and has made easier hydrolysis. Another route consists in the preparation of unsaturated PHAs which can be chemically modified. Pendant double bonds have been turned into carboxylic, hydroxyl or epoxy groups. Moreover these reactive functions were used for grafting oligomers of hydrolysable polylactic acid (PLA) or hydrophilic polyethylene glycol (PEG). Otherwise block copolymers with polycaprolactone (PCL) have been prepared, aiming at nanoparticles formation in the view of drug release. Therefore, the hydrophilic/hydrophobic balance of these materials was controlled by chemical modification and their stability/hydrolysis has been studied. Results have shown that the most suitable products in regard to hydrolysis concern PHAs containing carboxylic groups in side chains, noted poly(3hydroxyoctanoate-co-9-carboxy-3-hydroxydecanoate) and its derivatives. Carboxylic groups promote water penetration into the polymer and participate to ester groups hydrolysis through better water penetration and catalysis. [ABSTRACT FROM AUTHOR]

An optimisation technique using simulated annealing is described, in order to find the best placement of the harmonic filters to be installed in a distribution system with their minimum power size. The filtering currents are then calculated not to cancel the resulting harmonic voltages but to reduce their values with respect to the fixed limits. The objective is to minimise the power size in view of maximum savings in the equipment cost. The aboard power system of an electric propulsion ship with a great number of nonlinear loads is analysed in order to illustrate the efficiency of the optimisation method. [ABSTRACT FROM AUTHOR]

Although the use of stents has limited the incidence of restenosis, in-stent restenosis remains an important problem. In-stent restenosis is the result of a healing process that induced neointimal hyperplasia through mechanisms that are still not understood. The aim of this study was to analyze the histological consequences of the healing process following stent implantation. Internal mammary arteries from atheroslerotic patients undergoing coronary artery bypass surgery were stented and maintained in culture for 0–28 days. Stent implantation after predilatation induced an extensive loss of endothelial cells whereas direct stenting preserved endothelium between the struts. Morphometric analysis shows that stent placement induced neointimal thickening. Smooth muscle α-actin labeling indicates that neo-intimal formation was mainly due to proliferation and migration of smooth muscle cells. Smooth muscle cell proliferation, assessed by MIB-1 staining, was maximal at day 14 after stent insertion. Human mammary artery organ culture thus provides valuable information on histological consequences of stent implantation with or without predilatation regarding endothelial cell disappearance and neointimal hyperplasia. These data also demonstrate that neointimal thickening induced by stent implantation comprises an intrinsic component resulting from the vessel wall response to stent insertion and suggest that blood factors could play an amplifying but not necessary role. Copyright © 2004 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The crystal structure of Mo2.0 – xNi1.0 + xP ( x= 0.2) is determined by powder x-ray diffraction (monoclinic symmetry, new structure type, sp. gr. Im, a = 1.04036(5) nm, b= 0.84055(4) nm, c= 0.47357(2) nm, β = 91.538(3)°; Rint = 0.094, Rprof = 0.197). The 850°C section of the Mo–Ni–P phase diagram is studied in detail, and the crystal-chemical features of molybdenum nickel phosphides are discussed. [ABSTRACT FROM AUTHOR]

Thermal conductivity measurements of thin amorphous silicon films performed with a micro-thermistance mounted on an atomic force microscope are presented. A specific thermal model is implemented, and an identification procedure is proposed to extract the film contribution from the apparent thermal conductivity. Results show agreement with the literature regarding interface resistance data, but lower thermal conductivity values are obtained. [ABSTRACT FROM AUTHOR]

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Two precursors of taurine have been studied: cysteamine and hypotaurine. Cysteamine has been quantified in genital secretions and found in follicular fluids of all species tested. On the contrary cysteamine was not detected (or traces) in tubal fluids of the same species. Addition of 50, 100 or 250 μM of cysteamine to the maturation medium used in the culturing of bovine oocytes did not improve the cleavage rate nor the embryo's developmental potential in vitro. Furthermore, at 250 μM, cysteamine seems to be toxic to the embryo. Addition of 0.5–1 mM hypotaurine to the bovine embryo culture medium improved significantly blastocyst production and quality. The respective roles of these 2 taurine precursors on maturation and embryo development are discussed. [ABSTRACT FROM AUTHOR]

Taurine and/or hypotaurine are necessary compounds for sperm capacitation, fertilization and embryo development. Hypotaurine has a protective role against peroxidative damage. The object of this work was, on the one hand, to determine the precise amounts of hypotaurine and taurine in the sperm environment at the moment of fertilization, and on the other hand to evaluate the production of hypotaurine and taurine by oviduct epithelial cells. Hypotaurine and taurine were quantified in spermatozoa and seminal and tubal fluid of various species, and in secretions by oviduct epithelial cell layers . Significant amounts of taurine and hypotaurine were identified. Both compounds were quantified in pre-ovulatory follicular fluid, i.e. in one of the fluids present at the site of fertilization. We also observed that hypotaurine and taurine are synthesized and secreted by oviduct epithelial cells. We were able to demonstrate that hypotaurine is stable when added to an in-vitro fertilization (IVF) culture medium. The effects of this compound should be more carefully studied in human IVF. [ABSTRACT FROM PUBLISHER]

Racemic ((3S,4R)-(3R,4S))-3-methyl-4-benzyloxycarbonyl-2-oxetanone has been prepared by a simple and reproductible method starting from a racemic mixture of threo-((2S,3S)-(2R,3R))-3-methylaspartic acid as chiral precursor. This α, β substituted β-lactone has been polymerized anionically, using tetraethylammonium benzoate as initiator, to yield high molecular weight and amorphous racemic threo-poly(β-benzyl-3-methylmalate). The catalytic cleavage of protecting benzyl ester groups has been conducted in different solvents and racemic threo-poly(β-3-methylmalic acid) has been obtained in N-methylpyrrolidone at room temperature. Racemic threo-poly(β-3-methylmalic acid-co-benzyl-β-3-methylmalate) has been prepared by heterogeneous H/Pd charchoal catalyzed partial hydrogenolysis of the polymer precursor. Solubility of these different materials has been considered. Hydrolysis of threo-poly(β-3-methylmalic acid) has conducted to racemic threo-3-methylmalic acid. High resolution C NMR and selective INEPT NMR have been used for resonances assignment of polymers and copolymers. This new poly(β-hydroxy acid) type polyester expands the family of poly(β-malic acid) derivatives by opening the route for tailor making functional polystereoisomers with two stereogenic centers in the main chain and with the presence of an hydrophobic alkyl group and an hydrophilic carboxylic acid group in the macromolecule. [ABSTRACT FROM AUTHOR]

Cortical auditory evoked potentials (N1 wave) were studied in 24 adults (12 men, 12 women) and 20 children (12 boys. 8 girls; age: 4-8 years). In adults, this wave was recorded with maximal amplitude at frontocentral sites, peaking at about 100 ms poststimulation, whereas in children the auditory response displayed maximal amplitude at the midtemporal sites, with a positive wave at about 100 ms and a large negative wave at approximately 170 ms. Moreover, the modulatory effects of intensity on N1 amplitude were prominent at frontocentral sites in adults and at temporal sites in children. Frontocentral negative response was also recorded in children but was smaller in amplitude and longer in peak latency (around 140 ms) than in adults; responses were of greater amplitude at the frontal site than at the vertex before 6 years of age, whereas the reverse was more often found after this age. These data suggest great differences with age in the neural generators contributing to auditory evoked potentials recorded in the N1 latency range. [ABSTRACT FROM AUTHOR]

A caesarean section was performed on 30 cows before normal term and 16 to 20 hours after the induction of parturition with dexamethasone. During the surgical procedure, 20,000 U of bacterial collagenase was injected into the uterine artery of 15 of the cows. The average periods of retention of the fetal membranes were 40 hours in the treated cows and 114 hours in the control cows (P<0.001). At 36 hours after the surgery six of the treated cows (40 per cent) but all 15 of the control cows had retained fetal membranes. The collagenase-treated cows showed no abnormal clinical signs during the 10 days after the operation. [ABSTRACT FROM AUTHOR]

BN-Fe nanocomposite films have been produced by dual ion-beam sputtering codeposition. The effect of using a reactive nitrogen assistance beam during the elaboration process has been studied by transmission electron microscopy, selected area electron diffraction, grazing incidence small-angle x-ray scattering, and magnetic measurements. Experimental results show that without assistance, we produce nearly spherical Fe(B) nanoparticles (2-3 nm in diameter) exhibiting a superparamagnetic behavior. When growing under assistance, we obtain vertically elongated nanoparticles of paramagnetic Ζ-Fe[sub 2]N encapsulated in disordered hexagonal BN. This study demonstrates the possibility of producing encapsulated nanoparticles with high shape anisotropy by activating the surface diffusion of the incoming deposited species. [ABSTRACT FROM AUTHOR]

The present study evaluated: (1) in vivo follicular development in canine ovarian tissue after slow freezing and xenotransplantation; and (2) the use of erythropoietin (EPO) as an angiogenic factor to optimise the transplantation procedure. Frozen–thawed ovarian tissue from five bitches was grafted into severe combined immunodeficient (SCID) mice (n = 47) treated with or without EPO (500 IU kg[–1], once daily for 3 days) (Groups A and B, respectively) and analysed after 0, 1, 8 or 16 weeks. Follicle grade, follicle density, follicle morphology and stromal cells density were assessed by histological analysis, whereas vascularisation of the graft was quantified by immunohistochemistry with anti-ɑ-smooth muscle actin antibody. Despite a massive loss of follicles after grafting, secondary follicle density was higher at 8 and 16 weeks than at 1 week regardless of EPO treatment. EPO significantly improved early follicle morphology and stromal cell density after 8 weeks and blood vessel density at 16 weeks after transplantation (P < 0.05). Intact secondary follicles with more than three granulosa cells layers were observed 16 weeks after transplantation. The results suggest that canine ovarian tissue can be successfully preserved by our slow-freezing protocol because the tissue showed follicular growth after xenotransplantation. EPO treatment did not lessen the massive loss of follicles after transplantation. Cryopreservation is relevant to preserve endangered wildlife species or genetic resources in domestic animals. The aim of the present study was to assess the integrity and of frozen–thawed ovarian tissue from bitch after xenografting. Despite a massive follicular loss, a follicle growth was observed at 8 weeks post-transplantation and several well-developed intact secondary follicles were present at the end of the experiment. This confirms canine ovarian tissue is well preserved by our slow freezing process. [ABSTRACT FROM AUTHOR]

The mRNA expression of five enzymes: catalase, Cu-Zn-superoxide dismutase (Cu-Zn-SOD), Mn-superoxide dismutase (Mn-SOD), glutathione peroxidase (GPX), and γ-glutamylcysteine synthetase (GCS) each involved in protection against free radicals was studied in human and mouse oocytes. In the mouse, oocytes were collected at different stages of maturation in order to determine the storage of these transcripts. For the human, germinal vesicle (GV) oocytes harvested during intracytoplasmic sperm injection (ICSI) procedures and failed fertilized metaphase II (MII) oocytes were analysed. Human and mouse were compared in order to determine whether the differential developmental capacity of mouse and human preimplantation embryos in culture could be explained by the variations in the patterns of expression for these enzymes. mRNA expression for these enzymes was examined using reverse transcription-polymerase chain reaction (RT-PCR). In the mouse, all transcripts (except for catalase) were detected, whatever the maturation stage. No qualitative differences were detected between GV and MII oocytes. In human, all the enzymes (except for catalase) were expressed in MII oocytes and Cu-Zn-SOD was particularly highly expressed. Transcripts corresponding to GPX and Mn-SOD were not detected at GV stage but only at MII stage, suggesting that storage could occur between GV and MII stages. However, using 3′ end-specific primers for GPX and Mn-SOD, instead of the oligo(dT)[sub 12-18] primer, for the reverse transcription reaction, the transcripts for these antioxidants enzymes have been detected in human oocytes at the GV stage. This suggests the presence of maturation-specific polyadenylation of these transcripts. These enzymes can be considered as markers of cytoplasmic maturation. [ABSTRACT FROM AUTHOR]