Biofunctionalization of TiO2 surfaces with self-assembling oligopeptides in different pH and Ionic Strength conditions: Charge effects and molecular organization.

Self-assembling peptides (SAPs) were investigated by means of XPS and Angular Dependent NEXAFS spectroscopies, with the aim to probe the influence of pH and Ionic Strength conditions on the chemical structure and molecular organization of SAPs anchored on titania surfaces. XPS at the C1s, N1s, O1s core levels allowed to study surfaces and biomolecule/substrate interfaces. NEXAFS data allowed ascertaining that SAPs molecular structure is preserved upon grafting to the titania surface. Angular Dependent NEXAFS was used to investigate the influence of environmental conditions on the molecular organization behaviour. The objective of our study was to establish a set of methodologies for obtaining arrangements of well-organized biomolecules on scaffolds surfaces as a basic technology to develop and optimize cells adhesion and proliferation for tissue engineering applications.

[Scintigraphic detection of gastrointestinal hemorrhage. Value and limitations]. / Localisation scintigraphique des saignements digestifs. Intérêts et limites.

A technetium-99m labelled red blood cell scintigraphy was performed in 51 patients with an unexplained gastro intestinal bleeding. Static images were acquired on the injection day then at 24 hours. Forty one patients had a positive scintigraphy. In 13 patients with a positive scintigraphy, on the injection day (5 cases) and later (8 cases), no intestinal bleeding was identified in spite of further investigations guided by scintigraphy. In 24 patients, with a positive scintigraphy on the injection day (20 cases) and later (4 cases), an intestinal lesion was identified and treated; data were confirmed in 19 cases: there were 15 colon lesions, localized on caecum in 10 cases and 4 small bowel lesions. Clinical value and limitations of the investigation are discussed. The scintigraphic localization is usually accurate if the abnormal focus activity is noticed on the injection day. It helps to guide further investigations of the bleeding site. This non invasive method should be performed more quickly to help to localize intestinal bleeding which poses a diagnostic problem.

The potential usefulness of condensed image processing of sequential lymphoscintigrams in patients with lymphedema.

Condensed image processing (CIP), a computerized technique of scintiscans that generates a vertical distribution of activity as a function of time in a single image, was applied to isotopic lymphoscintigrams of four patients with leg lymphedema. By "condensing" information gained from multiple images into a single image, CIP better evaluates ascending progression of radiolabeled colloid in peripheral lymph and better localizes stagnant areas. In "high lymph flow failure," CIP also depicts radioactive "bursts" suggestive of increased lymphatic truncal contractility. This data processing method improves interpretation of dynamic scintiscan recordings and seems ideally suited for evaluation of peripheral lymph kinetics.

[The current role of lymphoscintigraphy in the study of lymphedema of the limbs]. / Place actuelle de la lymphoscintigraphie dans l'étude d'un lymphoedème des membres.

After a brief review of the classical methodology and results of lymphoscintigraphy, the technique is considered in terms of an original kinetic study approach. Immediately after distal subcutaneous injection of a technetium colloid (rhenium sulfocolloid), 40 1-min serial images of the limbs are recorded followed 4 h after injection by recording of static images. The main abnormalities detected by scintigraphy concern the lymphatic vessels, nodes and interstitium. They reveal the presence of lymphedema and provide information about its mechanism, indicating, particularly in the case of primary lymphedema, whether there is predominant hyperplasia or hypoplasia in vessels or nodes. Synoptic study of the initial dynamic recording based on simple examination of serial images is difficult. Complementary data provided by activity curves determined from manually selected regions of interest (ROI'S) are of limited value since the ROI'S correspond to superimposed spatial structures. Two data-processing techniques--the condensed image (CI) and factorial analysis (FA)--were therefore applied to dynamic scintigraphic recordings in order to study lymphatic progress of the radiotracer in the legs. A complete dynamic series is described in two IC, one for each leg. The CI, obtained by mounting the 40 serial images in vertical strips 1 pixel in width, describes the spatial distribution of radioactivity along the leg during recording. Factorial analysis provides automatic extraction of pure kinetic components or factors from the dynamic series despite their spatial superposition. The factors are described by factorial curves and factorial images representing the spatial identity of the factor. Three-factor FA was applied successively to each leg.(ABSTRACT TRUNCATED AT 250 WORDS)

Factorial analysis in radionuclide lymphography: assessment of the effects of sequential pneumatic compression.

The effects of intermittent pneumatic compression (IPC) in 12 patients with lower or upper limb lymphedema were studied using a computer-based technique (factorial analysis) of dynamic lymphoscintigraphy. After subcutaneous injection of radiocolloid into the first interdigital web space of the arm or leg, scintigraphic recordings consisted of 40 consecutive one-minute frames of both lower extremities or an edematous upper extremity. Pneumatic compression by Euroduc (6 patients) or by Lymphapress (6 patients) was applied during the final 20 minutes of the recording. A three factors factorial analysis (FA) was performed successively for each extremity. FA allowed "uncontaminated" curves to be displayed distinct from neighboring structures and corresponded to dynamic tracer activity in the interstitium, at the injection site, and within lymphatic vessels. Based on the results of lymphatic vascular factorial analysis, a beneficial effect of IPC was detected in 18 of 22 limbs examined. FA processing suggested that IPC facilitated radiocolloid transport in the proximal portion of the limb and also propelled tracer from the injection site toward the lymphatics. The effect of IPC was evident as soon as external compression therapy began and was similar with either mechanical unit. Residual tracer activity in peripheral lymphatics 20 minutes after application of IPC was higher in the edematous as compared with the normal limbs. FA processing is a new and potentially valuable method to evaluate the effects of external pneumatic compression in the management of peripheral lymphedema.

Factorial analysis of dynamic lymphoscintigraphy in lower limb lymphoedema.

The purpose of this work is to assess the contribution of factor analysis to the interpretation of dynamic lymphoscintigraphy. Twenty six adult patients with a lower limb lymphoedema and five control patients were studied. The technique involved a 3 mCi lymphovectoscint* 99Tcm-labelled ammonium sulphur colloid, bilateral pedal subcutaneous injection. Recording consisted of 40 consecutive 1-min frames of both legs followed by static pictures of each leg and pelvis at 40 min and 4 h after injection. The analysis of static pictures allowed a classification of patients into three groups: enhanced pattern, hypoplasia and dermic reflux. To evaluate better the different kinetic components of the sequential pictures, a factorial analysis (FA) software package was used. FA processing enabled the extraction from the dynamic series of different dynamic components, factorial curves and their associated factorial images which represent the anatomic structures with the same temporal behaviour. In each pattern the results of dynamic recording and of three FA factors were compared. FA provides an analytical temporal and spatial description of the dynamic sequence by extracting the different kinetic components; it yields a better differentiation of vessel and interstitium activity. It also provides some clues towards the understanding of oedema physiopathology and is of potential interest for the management of lymphoedema.