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Biomedical subjects

A Fery

Publications and source records attributed to A Fery.

At least 19 recordsLinked to original sources
PubMed2006

Direct method to study membrane rigidity of small vesicles based on atomic force microscope force spectroscopy.

Mechanical properties of lipidic membranes such as their bending rigidity are governing liposome morphology and play an important role in processes like membrane fusion and adhesion. Force versus deformation measurements are the most direct means to determine this, but so far experimental data is scarce and mainly stems from techniques that are limited to giant vesicles. We present atomic force microscope force spectroscopy as a method allowing force-deformation measurements of submicron vesicles. Bending rigidities of small unilamellar dipalmitoylphosphatidylcholine (DPPC) liposomes (R<200 nm) can be derived from the force-deformation data using analytical models based on shell theory and are in good agreement with independent measurements.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2006

Adhesion of polyelectrolyte microcapsules through biotin-streptavidin specific interaction.

Adhesion of PAH/PSS and PDADMAC/PSS capsules through electrostatic and specific interactions has been investigated using reflective interference contrast microscopy (RICM). Adhesion of capsules via electrostatic interactions was found to be spontaneous and strong. Capsules functionalized with poly(l-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) did not exhibit significant adhesion (as determined by the adhesion area) to streptavidin-coated substrates, whereas capsules functionalized with biotinylated PLL-g-PEG showed a significantly larger adhesion area. Using continuum mechanical models, the total adhesion energies for these cases were calculated and were found to correspond to several tens of individual biotin-streptavidin pairs. The application of specific interactions such as the biotin-streptavidin system for controlled capsule adhesion has been demonstrated in this study.

Adhesiveness↗
PubMed2006

Freestanding polyelectrolyte multilayers as functional and construction elements.

This article reviews the progress in the field of polyelectrolyte multilayer membranes with special attention to freestanding membranes. These can be prepared both in the form of hollow capsules and as flat membrane sheets. While (bio) functionality, or bioactivity as it is known, from solid supported multilayers is maintained, additional applications arise for the freestanding membranes in the fields of encapsulation, separation and micromechanics. The production processes and functionalities achieved for capsules and flat sheets. The integration of membranes into larger scale structures is essential for their use and an overview of existing strategies is given. In particular, the way in which arrays of micro-compartments can be built up is shown, and their potential for sensing and combinatorial chemistry discussed. Recent results on the applications of such systems as membrane sensors in the case of flat membrane sheets are also discussed.

Biocompatible Materials↗
PubMed2005

Salt softening of polyelectrolyte multilayer capsules.

The changes in the morphology and the mechanical properties of hollow polyelectrolyte multilayer capsules made from poly(styrenesulfonate)/poly(allylamine hydrochloride) in response to added salt were investigated. We found that capsules shrink in response to salt exposure. The effect depends strongly on the nature of the salt added and follows trends of the Hoffmeister series, with weakly hydrated cations inducing the strongest shrinking. For NaCl, we have investigated additional effects on capsule mechanical properties that are occurring above a 3 M salt concentration and we found that the morphological changes are accompanied by a pronounced softening of the capsule wall material, which we can quantify by analyzing the force response of capsules in the prebuckling regime. This shows that salts can act as plasticizers in the multilayers and induce annealing effects.

Journal Article↗
PubMed2003

Elastic properties of polyelectrolyte capsules studied by atomic-force microscopy and RICM.

Mechanical properties of polyelectrolyte multilayer capsules were studied using a new method combining atomic-force microscopy and reflection interference contrast microscopy. By measuring the force vs. deformation for poly(styrene sulfonate)/poly(allylamine) capsules the existence of different deformation regimes depending on the applied deformation was shown. The present paper focuses on the small-deformation regime. The elastic response of the deformed capsule was studied as a function of the wall thickness and the capsule size, and showed the theoretically expected variations. The Young modulus obtained from the experiments ranges between 1.3 and 1.9 GPa.

Capsules↗
PubMed1998

Spinodal dewetting in liquid crystal and liquid metal films

Theory predicts that dewetting of a homogeneous liquid film from a solid surface may proceed via unstable surface waves on the liquid. This phenomenon, usually termed spinodal dewetting, has been sought after in many systems. Observations in liquid crystal and liquid metal films showed that, as expected, the emerging structures were similar to those found for spinodal decomposition in mixtures. Certain differences, however, could be attributed to peculiarities of the wetting forces in these two dissimilar systems, thereby demonstrating the role of nonlinearities inherent in the wetting forces.

Journal Article↗
PubMed1998

Expression of DNA excision-repair-cross-complementing proteins p80 and p89 in brain of patients with Down Syndrome and Alzheimer's disease.

Although deficient DNA repair was proposed for neurodegenerative disorders including Down syndrome (DS), repair proteins for nucleotide excision repair have not been studied in brain yet. As one of the hypotheses for the pathogenesis of brain damage in DS and Alzheimer's disease (AD), is oxidative stress, and cells of patients with DS were shown to be more susceptible to ionizing irradiation. We decided to study expression of excision repair-cross-complementing (ERCC) gene products, proteins 80 and 89, representatives of repair genes known to be involved in the repair of different types of DNA damage. ERCC2-protein 80 kDa and ERCC3-protein p89 were determined in five individual brain regions of controls, aged DS and AD patients. Although different in the individual regions, DNA repair proteins were consistently higher in temporal and frontal lobes of patients with DS and higher in all brain regions of patients with AD. Our results are the first to describe DNA repair gene protein patterns in human brain regions providing the basis for further studies in this area. We showed that DNA repair genes ERCC2 and ERCC3 (excision-repair-cross-complementing) for nucleotide excision repair were increased at the protein level with the possible biological meaning that this increase may be compatible with and indicate ongoing (oxidative?) DNA damage.

Alzheimer Disease↗
PubMed1988

[Surgical treatment of metastases of the humerus].

Surgical treatment of metastasis disease of the humerus was applied for 46 lesions among 42 patients, i-e 22% of overall osteosyntheses for skeletal metastasis. Two patients only are still alive at 3 and 4 years. The mean survival time is 8.1 months and at 3 months 50% died. Metastasis disease of the humerus becomes evident late during the evolution of the primary cancer, but 26% are revealing lesions. For 9.5% the primary tumor remains unknown. After review of the surgical methods generally used, indirect osteosynthesis by intra-medullary pinning according to Hackethal, without bone cement, is alleged. So the arm is immediately mobilized and a complementary irradiation is applied in post-operative. Prophylactic fixation of impending fractures is encouraged in order to suppress pain, and for better function. This paper demonstrates the changing concept of internal fixation of pathologic fractures and recommends intra-medullary nailing or pinning.

Adult↗
PubMed1988

[Benign tumors of the spine in the adolescent. Surgical considerations apropos of 4 cases].

About 4 observations of benign tumours of the spine of the adolescent, we have studied the surgical aspect of the treatment of these lesion. The choice of the surgical approach is fundamental in view of the necessity of a complete exeresis, which implies techniques of spinal reconstruction and stabilization. Those problems are illustrated by: 2 cases of aneurysmal cyst, 1 case of eosinophilic granuloma, and 1 case of osteochondroma.

Adolescent↗
PubMed1987

[Technical development and radiological surveillance of the Schmitt minimadreporic uncemented total hip prosthesis. Evaluation of 275 arthroplasties with a follow-up of more than 6 years for the oldest cases].

The authors describe a porous-coated uncemented total hip prosthesis which has been used for more than six years: the Schmitt minimadreporic prosthesis. A homogenous series of 275 arthroplasties has been reviewed with a mean follow-up of three years and five months. The method of radiological assessment of the position of the femoral and acetabular components and their possible loosening is described in detail. Infection (0.72%) and aseptic loosening (1.8%) specific to this type of prosthesis was rare. For the series as a whole there were 92% of good, very good and excellent results and for 81 arthroplasties with a follow-up greater than four years the figure was 90%. The frequency of secondary displacement of the femoral component is emphasised, with 15 prostheses sinking downwards and 96 displacing into varus. Statistical analysis has shown the principal factors affecting the clinical result and has demonstrated the effect of resorption of the calcar in causing downward displacement of the femoral stem and insufficient filling of the medullary cavity on the development of varus angulation of the prosthesis.

Bacterial Infections↗
PubMed1986

[Tuberculous trochanteritis: value of ultrasonic diagnosis and x-ray computed tomography. Apropos of 3 cases].

Trochanteritis is a rare osteoarticular site of tuberculosis which initiates within the serous bursa of the gluteus maximus and extends only secondarily to the greater trochanter. Its course is a slow one. Diagnosis is usually delayed but should be made earlier by the use of ultrasound and the CT scan. These provide details of the bone remodelling detected on standard radiography, and show the presence of a variable fluid collection of a topography that attaches it to the serous bursa of gluteus maximus, and provides a guide to diagnostic needle puncture for biopsy. Overall data allow improved adaptation of medico-surgical treatment.

Aged↗
PubMed1984

[X-ray computed tomography in the study of anterior instability of the shoulder. Study of a series of 23 cases].

The place of standard CT scan imaging more particularly when combined with double contrast arthrography, is defined in the preoperative screening of patients with anterior instability of the shoulder. The joint scan provides complete data on the anatomic elements of the shoulder lesion, particularly with reference to the glenoidal labrum and the anterior capsular structure. It is also of major diagnostic value in painful subluxations.

Adolescent↗
PubMed1982

Therapeutic aspects of limb lesions due to hunting weapons: a study of twenty cases.

The authors report 20 cases of limb lesions provoked during hunting accidents by traditional weapons (gauges 12 and 20) or by 5.5 mm bullets of 22 L.R. Lesions caused by shotguns (gauge 12, 20) are much more serious when done point-blank or at very short shooting distance. The treatment of skin and bone lesions shall be realized in several steps: emergency removal of the foreign bodies with cutting out of non viable bone fragments. Immobilization and depending on the development, two therapeutic solutions may be chosen: either skin graft then bone graft or Papineau's method. Lesions caused by 5.5 mm bullets are much less serious because losses of substances are less important.

Adolescent↗
PubMed1981

Aseptic loosening of cemented total arthroplasties of the hip in relation to positioning of the prosthesis. New utilization of the Tschuprow-Cramer statistical test.

A statistical study of 1200 McKee-Farrar cemented total prostheses of the hip demonstrated the importance of a horizontal position of the cup and a valgus position of the prosthetic stem, in avoiding aseptic loosening of the prosthetic parts. A new test (the Cramer test) showed that a statistical bond exists between the position of the prosthesis and the occurrence of aseptic loosening.

Bone Cements↗
PubMed1981

[Shoulder radiographic evaluation. Radiographic examination of shoulder and scapular girdle trauma (author's transl)].

The Shoulder Radiographic Evaluation ("Complet Radiologique de l'Epaule") is completed by four positions: Standard A-P, Axillary axial view, Profil of the scapula, A-P in arm abduction. This paper focuses on the radiographic examination of the components of scapular girdle and shoulder articular complex. Several positions are described as routine positions in trauma. This radiographic procedure is of helpful interest for clinical, therapeutic and forensic applications.

Acromioclavicular Joint↗