KB scanning of X-ray beam for Laue microdiffraction on accelero-phobic samples: application to in situ mechanically loaded nanowires.

A mapping technique has been developed where a sub-micrometer focused polychromatic X-ray beam is scanned across a stationary sample instead of scanning the sample in front of the X-ray microbeam. This method is applied to a gold nanowire during its mechanical loading using the tip of an atomic force microscope. During the loading process, such a sample is `accelero-phobic', i.e. the sample scanning stages must not to be moved to avoid parasitic additional load. Without beam scanning, only one single position within the sample can be probed during the test. The probed material point may even change because of drifts or movements induced by the test itself. The new scanning approach facilitates the in situ mapping of the entire wire giving access to the evolution of the wire shape as well as to the boundary conditions. This novel scanning technique opens promising perspectives for studies where sample motion is forbidden because of the sample environment.

Interaction and behaviour imaging: a novel method to measure mother-infant interaction using video 3D reconstruction.

Studying early interaction is essential for understanding development and psychopathology. Automatic computational methods offer the possibility to analyse social signals and behaviours of several partners simultaneously and dynamically. Here, 20 dyads of mothers and their 13-36-month-old infants were videotaped during mother-infant interaction including 10 extremely high-risk and 10 low-risk dyads using two-dimensional (2D) and three-dimensional (3D) sensors. From 2D+3D data and 3D space reconstruction, we extracted individual parameters (quantity of movement and motion activity ratio for each partner) and dyadic parameters related to the dynamics of partners heads distance (contribution to heads distance), to the focus of mutual engagement (percentage of time spent face to face or oriented to the task) and to the dynamics of motion activity (synchrony ratio, overlap ratio, pause ratio). Features are compared with blind global rating of the interaction using the coding interactive behavior (CIB). We found that individual and dyadic parameters of 2D+3D motion features perfectly correlates with rated CIB maternal and dyadic composite scores. Support Vector Machine classification using all 2D-3D motion features classified 100% of the dyads in their group meaning that motion behaviours are sufficient to distinguish high-risk from low-risk dyads. The proposed method may present a promising, low-cost methodology that can uniquely use artificial technology to detect meaningful features of human interactions and may have several implications for studying dyadic behaviours in psychiatry. Combining both global rating scales and computerized methods may enable a continuum of time scale from a summary of entire interactions to second-by-second dynamics.

The structural properties of GaN/AlN core-shell nanocolumn heterostructures.

The growth and structural properties of GaN/AlN core-shell nanowire heterostructures have been studied using a combination of resonant x-ray diffraction, Raman spectroscopy and high resolution transmission electron microscopy experiments. For a GaN core of 20 nm diameter on average surrounded by a homogeneous AlN shell, the built-in strain in GaN is found to agree with theoretical calculations performed using a valence force field model. It is then concluded that for an AlN thickness up to at least 12 nm both core and shell are in elastic equilibrium. However, in the case of an inhomogeneous growth of the AlN shell caused by the presence of steps on the sides of the GaN core, plastic relaxation is found to occur. Consistent with the presence of dislocations at the GaN/AlN interface, it is proposed that this plastic relaxation, especially efficient for AlN shell thickness above 3 nm, is promoted by the shear strain induced by the AlN inhomogeneity.

[The radiological report: shaping it up]. / Le compte-rendu radiologique: à fond la forme.

The studies found in the literature investigated the structure of the radiological report, its standardization, communication with the general physician, regulations, and the medicolegal importance of the report. What to include in terms of content was most often considered: identification, clinical context and questions asked, technique and technical limitations, ordered results, relevant negative elements, a conclusion including a response to the question, diagnostic orientation, and suggestions for other examinations if necessary. In terms of the report's form, computerized reports have advanced the debate, opposing free composition and the structured report. No recommendations on the style were found in the recent studies, even though the problem is not a new one. In 1904, Hickey introduced the term "interpretation." In 1922, he observed that the style of reports was always individualistic and often eccentric. He suggested standardizing the reports to "avoid verbosity and encourage concision and clarity." After revising the information that should be included in a report, we wish to emphasize the form and style of the writing. This is not a scientific work, but rather we wish to express our opinion through a critical analysis based on examples taken from patient files. Many reports contain needlessly repeated words and language tics that harm the credibility of the analysis. The main qualities of the radiological report that are useful for the clinician are clarity, concision, and results correlated with the clinical situation.

The cellular toxicity of two antitumoural agents derived from platinum, cisplatinum versus oxaliplatinum, on cultures of tubular proximal cells.

There is a large scope for the use for cisplatin and its derivatives in the treatment of human malignancies. Nephrotoxicity is their most important use-limiting factor. The aim of this study has been to compare cisplatin (CDDP) and oxaliplatin (1-OHP), a new derivative, on cultures of tubular proximal cells. Three cells models were used: primary culture of rabbit kidney, proximal tubular cells (RPTC) and established opossum kidney (OK) and pig kidney (LLC-PK1) epithelial cell lines. Results indicate that in these three culture systems, the cytotoxicity-ranking of the two molecules were in agreement with their in vivo nephrotoxicity (CDDP > 1-OHP), but were less cytotoxic for OK and LLC-PK1 cells than for RPTC. Functional and biochemical evaluations in RPTC indicate that toxic effects of platinum derivates are exerted on DNA, protein synthesis and glucose uptake. 1-OHP effect on DNA synthesis seems to be more effective, but induced a more progressive cytotoxicity. Alteration of glutathione-dependent detoxication activities may reflect the occurrence of a lipid peroxidation process. The present study showed that 1) RPTC are more suitable that LLC-PK1 or OK cells for investigating the nephrotoxicity of platinum derivatives; 2) 1-OHP seems to have a more powerful pharmacological effect than CDDP. The toxic effect ratio seems to promise greater safety with 1-OHP than with CDDP.

Some milestones in in vitro organ Toxicity Assessment. The Kidney as a Case Study.

The expression of target organ toxicity ranges from subtle abnormalities of cellular organelles to permanent loss of organ function. The selective targeting of chemicals for discrete regions and cell types of a given organ is frequently due (besides some pharmacodynamic mechanisms) to the fact that target cells may express unique biochemical or functional characteristics predisposing them to chemically induced injury. In vitro models commonly used in target organ toxicity tests include perfused organ preparations, isolated tissue preparations, single-cell suspensions and tissue culture systems. Although these systems have proved their usefulness for acute toxicity tests, there is still a great need for in vitro models to be used for chronic toxicity tests. Among the systems listed above, the single-cell culture technique may be adapted to long-term study requirements. The example of kidney proximal tubules is taken to illustrate the necessity for extensive characterization of the actual capacities of the models in term of phenotypic profiling, energy status, drug detoxication activities, specific transport systems and organ-specific differentiated functions. LLC-PK1, LLC-RK1, NRK and OK cell lines are compared with primary cultures of rat, rabbit and human proximal tubule cells. The importance of the cell culture environment on the cell phenotypic profile, and its subsequent response pattern to toxicant exposure, are described using gentamicin and platinum derivatives as examples. In terms of experimental strategy, choice of cell type, choice of species of origin, choice of doses, choice of duration, continuous or discontinuous exposure, and whether to study the recovery phase, are crucial issues for designing models mimicking more closely the in vivo situation. The identification of relevant endpoints, allowing discrimination between general cell toxicity and specific organ toxicity, has not been sufficiently explored in vitro. Scientifically based endpoints referring to the background studies conducted by biochemists or physiologists should be selected and included in experimental designs dealing with organ toxicology in vitro. Conceptually, relevant specific target-organ toxicity could be investigated by the use of multiple cell types and by analysis of the difference in concentration between the cytotoxic concentration threshold and the specific endpoint alteration threshold.

Role of viscous guar gums in lowering the glycemic response after a solid meal.

The aim of the present study was to investigate how guar gum viscosity acts on starch digestion and glucose absorption in humans. Six healthy subjects received a mixed diet composed of 60.4% carbohydrate in the form of maize glucose or pregelatinized starch, to which was added 5.6% low- or high-viscosity guar gums. Meals were ingested or instilled in the duodenum and postprandial insulin and glucose responses were monitored for 3 h. Infusion of meals containing glucose showed that the delay in the diffusion rate to the duodenal mucosa due to bolus viscosity was not significant. Infusion of meals containing starch showed that a decrease in the digestion rate of starch in the upper small intestine accounted for part of the effect of viscosity on glycemic response, whereas the main effect of guar gum was apparently to slow gastric emptying.

[Toxic effect of two antitumoral agents derived from platinum, the cisplatin and the oxaliplatin on primary cultures of proximal tubular cells of the kidney in rabbits]. / Action toxique de deux agents antitumoraux dérivés du platine, le cisplatine et l'oxaliplatine sur des cultures primaires de cellules tubulaires proximales de rein de lapin.

There is a large field of use for cisplatin and its derivatives in the treatment of human malignancies. The nephrotoxicity is their most important use-limiting factor. The aim of this work has been to study comparatively the cisplatin and a new molecule, the oxaliplatin on primary culture of proximal tubular cells of rabbit kidney. Several markers, functional, enzymatic and biochemical have been evaluated after exposure to platinum's derivatives. The results indicates that their toxic effects are exerted on DNA and proteins synthesis, and for the cisplatin on the glucose uptake. Oxalyplatin's effect on DNA synthesis seems to be more effective, but induced a more progressive cytotoxicity. The lipids peroxidation's role with abnormalities of glutathione dependent detoxication system of the cell is possible. In conclusion, oxaliplatin seems to have a pharmacological effect more powerful than cisplatin. Its low dose effect ratio seems to promise greater safety in its use.

Modulation of glycolysis induction in primary cultures of rabbit kidney proximal tubule cells: the role of shaking, glucose and insulin.

We have assessed the impact of increasing oxygen availability on cellular phenotype expression of rabbit proximal tubule cells in primary culture developed with variable glucose and/or insulin contents. To mitigate hypoxia at the cell/medium interface, cells were shaken for the whole culture duration and their expressed phenotype was compared with those expressed by static cultures. O2 and CO2 tensions were kept constant in the incubator atmosphere. Glycolysis and gluconeogenesis pathways, detoxication system, and mitochondrial, apical and basolateral membrane marker enzyme activities were assessed. This study showed that the induction of glycolysis which appear in primary cultures of proximal tubule cells may be partially prevented by continuously shaking the cultures. This effect was more marked in the presence of glucose, suggesting better substrate oxidation in shaken cultures.

Insulin and glucose impact on functional and morphological differentiation of rabbit proximal tubule cells in primary culture.

Glucose and insulin impact on cellular phenotype expression was assessed on rabbit proximal tubule cells in primary culture. Glycolysis, gluconeogenesis pathways and lysosomal, mitochondrial, detoxication system, apical and basolateral membrane marker enzyme activities were assessed. Both insulin and glucose deprivation partially prevented the rise in glycolysis and delayed the drop of gluconeogenesis pathways. Scanning electron microscopy analysis of the apical surface of the monolayer revealed a much higher density of microvilli in glucose-free cultures compared to cultures developed with glucose. In conclusion, culture medium deprivation in both glucose and insulin allowed closer functional, biochemical and morphological properties to those which exist in the in vivo situation for proximal tubule cells.

Influence of particle size and sources of non-starch polysaccharides on postprandial glycaemia, insulinaemia and triacylglycerolaemia in pigs and starch digestion in vitro.

Physico-chemical properties of dietary fibres might be involved in metabolic control, particularly of the postprandial blood glucose response. The aim of the present study was to look at the effects of the content of soluble fibres and of the particle size of solid fibres on in vitro and in vivo starch hydrolysis and on the subsequent glucose absorption as well as the triacylglycerolaemia. Two sources of dietary fibres, one, with soluble fibres (beet pulp), the other with mostly insoluble fibres (wheat bran), were added at the rate of 60 g/kg to a meal simulating human food. The fibre sources were ground in order to obtain two different particle sizes (250 and 500 microns). Beet pulp decreased significantly (P < 0.05) initial in vitro hydrolysis whereas wheat bran increased starch hydrolysis in the first 10 min. Wheat bran and beet pulp, whatever its particle size, lowered the post-prandial triacylglycerol response. No significant effect was found with dietary fibre-supplemented diets on postprandial glycaemic and insulinaemic values. High correlation was found between initial in vitro starch hydrolysis and mean areas under the insulinaemic curves. This in vitro model can be used to predict initial in vivo digestion of carbohydrates from complex foods.

Characterization of gentamicin-induced dysfunctions in vitro: the use of optimized primary cultures of rabbit proximal tubule cells.

Compared to prior studies which frequently pinpoint the impairment of one parameter or function, this paper reports for the first time an extensive characterization of the toxic effects of gentamicin in a single model of primary cultured rabbit proximal tubule cells developed without insulin and glucose. Biochemical, functional and morphological approaches were used. Cellular response pattern was examined after a 72-h exposure during either the exponential growth phase or the stationary confluency phase of the culture to 0.2, 1, and 2.5 mM gentamicin. The biochemical study after gentamicin exposure showed increased activities for N-acetyl-beta-D-glucosaminidase and alkaline phosphatase, decreased activities for sphingomyelinase, cathepsin B, Na+/K(+)-ATPase, lactate dehydrogenase and NADPH cytochrome C reductase. Functional evaluation revealed decreased protein synthesis and alpha-methylglucose transport after gentamicin exposure. Morphometric study made it possible to show that the density of lysosomes, the cell fractional volume of the lysosomal compartment, and the mean size of the lysosomal profiles are increased in the cells. Intracellular accumulation of gentamicin in proximal tubular cells was dose dependent and reached high levels in cultured cells. In conclusion, this model compared to others in the literature allowed us to demonstrate in vitro a close response pattern to the in vivo situation after gentamicin exposure.