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Biomedical subjects

M Salomé

Publications and source records attributed to M Salomé.

7 recordsLinked to original sources
PubMed2003

Evidence for various calcium sites in human hair shaft revealed by sub-micrometer X-ray fluorescence.

New information about calcium status in human scalp hair shaft, deduced from X-ray micro-fluorescence imaging, including its distribution over the hair section, the existence of one or several binding-types and its variation between people, is presented. The existence of two different calcium types is inferred. The first one corresponds to atoms (or ions) easily removable by hydrochloric acid, located in the cortex (granules), in the cuticle zone and also in the core of the medulla, which can reasonably be identified as calcium soaps. The second type consists of non-easily removable calcium atoms (or ions) that are located in the medulla wall, probably also in the cuticle, and rather uniformly in the cortex; these calcium atoms may be involved in Ca(2+)-binding proteins, and their concentration is fairly constant from one subject to another. In addition to its nonuniform distribution across the hair section, the second striking feature of the first type calcium content is its high variability from one subject to another, by up to a factor 10. We expect this information to be useful for analyzing in more detail the relationship between hair calcium and environmental and medical factors.

Calcium↗
PubMed2000

Perspectives in three-dimensional analysis of bone samples using synchrotron radiation microtomography.

In this paper we present a methodology based on 3D synchrotron radiation microtomography to analyze non-destructively 3D bone samples. After a technical presentation of the imaging system and the image analysis techniques, we report results on three-dimensional analysis of vertebral samples from women of different ages. The new capabilities of this technique for the investigation of bone are discussed. They include a high spatial resolution down to the micron level, a high density resolution allowing a local quantification of bone mineralization, phase contrast imaging and advances in 3D image analysis.

Adult↗
PubMed1999

A synchrotron radiation microtomography system for the analysis of trabecular bone samples.

X-ray computed microtomography is particularly well suited for studying trabecular bone architecture, which requires three-dimensional (3-D) images with high spatial resolution. For this purpose, we describe a three-dimensional computed microtomography (microCT) system using synchrotron radiation, developed at ESRF. Since synchrotron radiation provides a monochromatic and high photon flux x-ray beam, it allows high resolution and a high signal-to-noise ratio imaging. The principle of the system is based on truly three-dimensional parallel tomographic acquisition. It uses a two-dimensional (2-D) CCD-based detector to record 2-D radiographs of the transmitted beam through the sample under different angles of view. The 3-D tomographic reconstruction, performed by an exact 3-D filtered backprojection algorithm, yields 3-D images with cubic voxels. The spatial resolution of the detector was experimentally measured. For the application to bone investigation, the voxel size was set to 6.65 microm, and the experimental spatial resolution was found to be 11 microm. The reconstructed linear attenuation coefficient was calibrated from hydroxyapatite phantoms. Image processing tools are being developed to extract structural parameters quantifying trabecular bone architecture from the 3-D microCT images. First results on human trabecular bone samples are presented.

Aged↗
PubMed1996

N-acetyl-heparosan lyase of Escherichia coli K5: gene cloning and expression.

The structure of the capsular polysaccharide of Escherichia coli K5 is identical to that of N-acetyl-heparosan, a nonsulfated precursor of heparin, which makes this E. coli antigen an attractive starting point for the chemical synthesis of analogs of low-molecular-weight heparin. This polysaccharide is synthesized as a high-molecular-weight molecule that can be depolymerized by an enzyme displaying endo-beta-eliminase activity. The eliminase-encoding gene, designated elmA, has been cloned from E. coli K5 by expression in E. coli K-12. The K-12 genome is devoid of the elmA sequence. The elmA gene product is 820 amino acids long. Active recombinant eliminase is produced by K-12 cells in both cell-bound and secreted forms. Deletion analyses have shown that the C terminus and the N terminus are required for activity and secretion, respectively.

Amino Acid Sequence↗
PubMed1995

Adaptive predictive control of dissolved oxygen concentration in a laboratory-scale bioreactor.

We present an algorithm for the adaptive control of dissolved oxygen concentration in a bioreactor, based on the agitation rate. The dynamics are represented by an incremental first-order model with variable dead-time and parameters. These are estimated on-line by a recursive least-squares identification method with a forgetting factor and a constant sensitivity. The model is employed to predict the behaviour of the dissolved oxygen concentration over a finite horizon, using an original method which requires little computation. Then, a Generalized Predictive Control optimisation strategy computes the agitation rate from the predictions and the desired set point, while gradually updating the controller smoothness. This algorithm, which requires little preliminary knowledge, has been implemented on a laboratory-scale fed-batch bioreactor for which the use of conventional controllers showed limited performance, due to the unpredictable and evolutive nature of the dynamics. The new controller proved to be robust and effective over a wide range of operating conditions, while requiring no operator adjustments.

Algorithms↗
PubMed1983

Cytochemical localization of lipases during spore germination from Bryum capillare.

In the oil containing spores of Bryum capillare, lipid breakdown occurs within three days after sowing. The periods of activity of acid, neutral and alkaline lipases are coincident. They start at the first day after sowing the spores. After 3 days of germination, when storage fats forming large globules are mobilised no lipase activity could be detected any longer in the glyoxysomes. Acid lipase is preferentially located in spherosomal membrane but is also present at the glyoxysomal membrane. Alkaline lipase is specifically located in the glyoxysomes and mitochondria. A cooperation presumably exists between acid and alkaline lipases in the hydrolysis of monoglycerides at the glyoxysomal level. Neutral lipase activity is localized at the spherosomal membrane, in the endoplasmic reticulum and in dictyosomes. It is absent from glyoxysomes.

Histocytochemistry↗