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Journal Article↗
Biomedical subjects
L Debelle
Publications and source records attributed to L Debelle.
The structures of elastins and their function.
Elastin structures and their significance towards elastic recoil properties have been reviewed. Starting from the initial hypothesis that elastin conformation is conditioned by that of its monomer, the structure of tropoelastin was first described using theoretical and experimental methods and a beta class folding type was evidenced for the isolated unbound tropoelastin molecules. The structure of elastin in the solid state was consistent with that of its monomer and consequently, fibrous elastin appeared constituted of globular tropoelastin molecules. Finally, theoretical and experimental considerations have led us to the conclusion that the functional form of the elastomer, water swollen elastin, could be a triphasic system comprising the protein chains, hydration water and solvent water. Following this description, the dynamic structural equilibria occurring within elastin hydrophobic domains and the plasticizing effect of water could explain elastin elasticity, in keeping with a classical entropic mechanism.
Amino Acid Sequence↗
Elastin: molecular description and function.
Elastin, the protein responsible for the elastic properties of vertebrate tissues, has been thought to be solely restricted to that role. As a consequence, elastin was conventionally described as an amorphous polymer. Recent results in the biomedical, biochemical and biophysical fields have lead to the conclusion that the presence of elastin in the extracellular space has very complex implications involving many other molecules. The present review describes the current state of knowledge concerning elastin as an elastic macromolecule. First, the genetic, biological, biochemical and biophysical processes leading to a functional polymer are described. Second, the elastic function of elastin is discussed. The controversy on elastin structure and elasticity is discussed and a novel dynamic mechanism of elasticity proposed. Finally, pathologies where the elastin molecule is involved are considered. This updated description of functional elastin provides the required background for the understanding of its pathologies and defines clearly the properties a substance should possess to be qualified as a good elastic biomaterial.
Animals↗
[Angio-MRI of the lower limbs using the moving-bolus technic without subtraction: technical note].
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Aged↗
[Computed tomography study of the sigmoid colon: discriminating diagnostic criteria and interobserver correlations].
PURPOSE: To assess the value of pericolonic findings at CT in the evaluation of the sigmoid colon. MATERIALS AND METHODS: A total of 210 CT examinations were retrospectively reviewed by 3 blinded radiologists. Data was analyzed to determine the interobserver correlation and the value of pericolonic and colonic wall findings in diagnosis of sigmoid colon pathology. RESULTS: The interobserver correlation for pericolonic findings was equal to or superior to that for colonic wall findings. The presence of abnormal pericolonic fat was the most sensitive (88%) and specific (93%) sign to differentiate a diseased sigmoid colon from a normal one or from sigmoid diverticulosis. Wall-thickening was less sensitive (82%) and specific (76%). Findings suggesting malignancy over diverticulitis included acute zone of transition, focal fatty infiltration, and lymph nodes. Symmetrical and circumferential wall thickening, target-like enhancement, and local fatty proliferation were findings suggesting colitis over diverticulitis. Wall thickening more than 15 mm, involvement of 15 cm or less, asymmetrical involvement, acute zone of transition, and homogeneous or heterogeneous enhancement were findings suggesting malignancy over colitis. CONCLUSION: To render a diagnosis, the evaluation of the fat infiltration must prevail on the parietal thickening appreciation.
Adipose Tissue↗
The secondary structure and architecture of human elastin.
The presented work constitutes the first structural characterization of both insoluble human elastin and its solubilized form, kappa-elastin. Structural data were reached following the use of Fourier transform infrared, near infrared Fourier transform Raman and circular dichroism optical spectroscopic methods and their quantitative analysis permitted us to estimate approximately 10% alpha-helices, approximately 35% beta-strands and approximately 55% undefined conformations in the global secondary structure of insoluble human elastin in the solid state. Following the use of the LINK method, the probable local distribution of the secondary-structure elements along the sequence was determined and compared to that obtained for bovine elastin, the historical standard of elastin. This comparison led us to propose a globular architecture for the human elastomer and permitted us to delineate some elements of its structure-elasticity relationship.
Amino Acid Sequence↗
[Massive bone destruction: an atypical sign of orbital lymphoma].
A case of lacrimal sac malignant lymphoma with frank bony distruction visible on computed tomography is described. This is an unusual radiologic finding which does not rule out lymphoma. Biopsy is mandatory to complete the diagnosis.
Adult↗
Bovine elastin and kappa-elastin secondary structure determination by optical spectroscopies.
Elastin is the macromolecular polymer of tropoelastin molecules responsible for the elastic properties of tissues. The understanding of its specific elasticity is uncertain because its structure is still unknown. Here, we report the first experimental quantitative determination of bovine elastin secondary structures as well as those of its corresponding soluble kappa-elastin. Using circular dichroism and Fourier transform infrared and near infrared Fourier transform Raman spectroscopic data, we estimated the secondary structure contents of elastin to be approximately 10% alpha-helices, approximately 45% beta-sheets, and approximately 45% undefined conformations. These values were very close to those we had previously determined for the free monomeric tropoelastin molecule, suggesting thus that elastin would be constituted of a closely packed assembly of globular beta structural class tropoelastin molecules cross-linked to form the elastic network (liquid drop model of elastin architecture). The presence of a strong hydration shell is demonstrated for elastin, and its possible contribution to elasticity is discussed.
Amino Acids↗
Predictions of the secondary structure and antigenicity of human and bovine tropoelastins.
Secondary structure and antigenicity predictive methods have been applied to the sequences of human and bovine tropoelastins in order to have some insight into the molecular structure of its insoluble counterpart, i.e., elastin. For both tropoelastins, all the predictions yielded 11 major regions, in which the pleated conformation was predominant, separated by 10 strong helical segments of various lengths located within alanyl rich regions of the chains. The overall conformations of human and bovine tropoelastins were estimated to contain 18 +/- 5% alpha-helices, 63 +/- 17% beta-sheets, 13 +/- 13% beta-turns and 6 +/- 6% random coil. For both tropoelastins, antigenicity predictions indicated the presence of seven synthetic decapeptides corresponding to continuous linear epitopes of the molecule. Some of the predicted epitopes are located in the same regions in both species while others are not. These predictions have allowed us to propose an alpha/beta conformation for tropoelastin. Therefore this extracellular matrix macromolecule might be more structured (10 helical segments for about 18% of the overall structure) than previously suggested.
Algorithms↗