Nanoscale mechanical properties of chitosan hydrogels as revealed by AFM.

In the context of tissue engineering, chitosan hydrogels are attractive biomaterials because they represent a family of natural polymers exhibiting several suitable features (cytocompatibility, bioresorbability, wound healing, bacteriostatic and fungistatic properties, structural similarity with glycosaminoglycans), and tunable mechanical properties. Optimizing the design of these biomaterials requires fine knowledge of its physical characteristics prior to assessment of the cell-biomaterial interactions. In this work, using atomic force microscopy (AFM), we report a characterization of mechanical and topographical properties at the submicron range of chitosan hydrogels, depending on physico-chemical parameters such as their polymer concentration (1.5%, 2.5% and 3.5%), their degree of acetylation (4% and 38.5%), and the conditions of the gelation process. Well-known polyacrylamide gels were used to validate the methodology approach for the determination and analysis of elastic modulus (i.e., Young's modulus) distribution at the gel surface. We present elastic modulus distribution and topographical and stiffness maps for different chitosan hydrogels. For each chitosan hydrogel formulation, AFM analyses reveal a specific asymmetric elastic modulus distribution that constitutes a useful hallmark for chitosan hydrogel characterization. Our results regarding the local mechanical properties and the topography of chitosan hydrogels initiate new possibilities for an interpretation of the behavior of cells in contact with such soft materials.

[Budd-Chiari syndrome due to membranous obstruction of the inferior vena cava of congenital origin. Ten-year follow-up after radiologic treatment]. / Syndrome de Budd-Chiari par obstruction membraneuse de la veine cave inférieure d'origine congénitale. Suive de 10 ans après traitment radiologique.

We report a case of Budd-Chiari syndrome due to membranous obstruction of the inferior vena cava with a congenital malformation composed of a left inferior vena cava at the sub-renal level with an azygo-caval continuation without a retrohepatic segment of the inferior vena cava. To our knowledge, this is the first report of this association. The congenital venous malformation suggests a congenital etiology to the inferior vena cava membrane. The membranous obstruction was treated by percutaneous transluminal angioplasty. During the 10-year follow-up, there was no recurrence of the membranous obstruction as seen with Doppler ultrasound and magnetic resonance imaging.

[Occlusive pneumatosis cystoides intestinalis of the left colon. Which therapeutic approach to choose?]. / Pneumatose kystique occlusive du côlon gauche. Quelle attitude thérapeutique faut-il adopter?

A rare case of colonic occlusion due to cystic pneumatosis required surgical cure. The problems related to the pathogenesis and, especially, the therapeutic approach to this disease were emphasized.

[Laser therapy of villous rectocolonic tumors. Evaluation of results by multivariate analysis]. / Traitement par laser des tumeurs villeuses rectocoliques. Evaluation des résultats par analyse multifactorielle.

One hundred and twenty-four patients (mean age: 70 years) with a villous tumour of the rectum (n = 98) or the colon (n = 26) were treated by laser therapy from 1985 to 1991. Initial complete eradication was obtained in 93.5% of cases with a median time of 16 months. Using multivariate analysis, the tumor size (> 4 cm) only was predictive of eradication (P < 0.001). At 6 and 12 months, the actuarial eradication rates were 91 and 98% for small tumours versus 45 and 74% for larger tumours respectively. The actuarial recurrence rates were 10.5, 23, and 37% at 6, 12 and 24 months, and no longer increased after 3 years. No predictive factor of recurrence was isolated by multivariate analysis. Seven complications (5.6%) and 4 malignant transformations (3.4%) occurred. This study confirms the efficiency and low morbidity of laser therapy, especially in patients with small tumors, less than 4 cm in size.

[Predictive factors of response to chemotherapy in epidermoid cancer of the esophagus. Study apropos of 60 patients and evaluation of a response score]. / Facteurs prédictifs de réponse à la chimiothérapie du cancer épidermoïde de l'oesophage. Etude à propos de 60 patients et élaboration d'un score de réponse.

The aim of this study was to select predictive factors for response to chemotherapy in esophageal squamous cell carcinoma. Sixty patients, aged between 39 and 77 years (mean 61.5) received two initial chemotherapy sessions of 5 FU (1 mg/m2/24 h) and cisplatinum (20 mg/m2/24 h) during four days. Sixteen clinical, endoscopic, biological, and histological factors were collected. The response to chemotherapy was evaluated one month after completion of the second session by means of endoscopic and computed tomographic data. Thirty-two percent (CI: 20-44 percent) of patients had an objective response to chemotherapy (according to WHO criteria). Univariate analysis showed two predictive factors: obstructing pattern of tumor (P less than 0.01) and albuminemia less than 35 g/l (P less than 0.01). A response score was calculated with a stepwise regression model. The score correctly predicted a satisfactory response to chemotherapy with a sensitivity and specificity of 84.2 and 73 percent, respectively. Overall survival of these patients was statistically higher (P less than 0.001) compared with patients without any response. A satisfactory response to chemotherapy in patients with esophageal squamous cell carcinoma can be expected according to certain pretreatment factors.

[Analysis of cellular DNA content by flow cytometry in epidermoid carcinoma of the esophagus]. / Analyse du contenu cellulaire en ADN par cytométrie en flux dans le carcinome épidermoïde de l'oesophage.

Flow cytometric DNA analysis was performed in 35 patients with squamous cell carcinoma of the esophagus. The aim of this study was a) to establish a tumoral DNA pattern, b) to determine an objective parameter correlating with tumoral response to chemotherapy (5 FU-cisplatin). DNA analysis was performed in perendoscopic ranged tumoral biopsy specimens to determine the DNA ploidy (DNA index) and S phase fraction. Tumor diameter and length were evaluated by computed tomography (CT) before and after chemotherapy in 24 patients. The relative variation of this product determined a CT index. Before chemotherapy, 82 percent (76/93) of the specimens were available for assessment; 72 percent (26/36) of the tumors were aneuploid. In these tumors, the DNA index ranged from 1.23 to 2.80. Five tumors had two distinct and simultaneous aneuploid populations. CT index values were not significantly different according to the ploidy (diploid, aneuploid), the S phase fraction (low, high), the DNA content modification after chemotherapy (absent, present). In this study, DNA analysis did not allow to select patients with higher response to chemotherapy. The inter- and intratumoral phenotypic heterogeneity may be one of the responsible factors.

[Bilateral abscess of the psoas with aero-anaerobic digestive flora in advanced tuberculosis]. / Abcès bilatéral du psoas à flore digestive aéro-anaérobie lors d'une tuberculose évolutive.

The authors report a case of bilateral psoas abscess without spondylodiscitis, occurring in the course of an advanced pleuro-pulmonary tuberculosis. The dual bacteriological composition of the pus with an aero-anaerobic flora on direct examination, and mycobacterium tuberculosis in the culture, as well as the presence of an obstructive appendicitis noticed during the surgery, open the discussion of its pathogenesis.

[Mixed carcinoid tumor-adenocarcinoma of the stomach. Review of the literature, apropos of a case]. / Tumeur mixte carcinoïde-adénocarcinome de l'estomac. Revue de la littérature, à propos d'un cas.

We report a case of mixed tumor of the stomach with a double histological population: carcinoid and adenocarcinoma. The carcinoid component presented an usual morphological pattern with "atypical" elements, and without argyrophilic cells; the carcinoid cells were exclusively marked by an anti-serotonin serum. The other component was a poorly differentiated carcinoma, with muco secretion, which was not marked by and anti-carcino-embryonic antigen serum. The limit between the two components was sharp. The association of mucin in the carcinoma and serotonin in the carcinoid component was an argument in favour of the diagnosis of mixed tumor carcinoid-adenocarcinoma (composite tumor) of the stomach. The evolution after operation leaded to a local recurrence and to the death 10 months later, in spite of chemotherapy. The existence of composite tumors raises nosological, histogenetical and diagnostic problems, which are discussed in this work. The prognosis of these tumors is unknown and therapeutic possibilities seem to be scanty.

[Chronic atrophic gastritis with carcinoid tumor and microcarcinoidosis. Report of a case with immunohistochemistry and ultrastructure study]. / Gastrite chronique atrophique avec tumeur carcinoïde et "microcarcinoïdose". Rapport d'un cas avec étude immunohistochimique et ultrastructurale.

Gastric endoscopy of a 40 year old woman suffering from ill-defined epigastralgy revealed a carcinoid tumor apparently located at the mucous membrane. The tumor was neither argyrophil nor argentaffin. Immunohistochemical tests for VIP, gastrin and serotonin were negative. Biological examinations indicated hypochrome anemia and hypergastrinemia (greater than 800 pg/ml). The excision was completed by a gastrectomy of 2/3 with a Pean anastomosis. No residual tumor was detected but the fundic mucous membrane showed considerable atrophic gastritis together with a marked hyperplasia of endocrine cells giving an aspect of microcarcinoidosis. Immunohistochemical studies showed that most of the cells produced serotonin while a few cells produced gastrin or VIP. Control biopsies of the stump showed similar hyperplasia of the endocrine cells and ultrastructural studies confirmed the polymorphism of the islets. The present observation is compared to analogous cases cited in the literature. The pathogenic mechanism possibly linked to the capacity of gastrin in stimulating endocrine cells is discussed. The prognosis in these carcinoid tumors appears to be the same as in other gastric carcinoid tumors. In particular, a recent observation (Goldman et al., 1981) illustrated their aptitude to lead to metastases.

[Interest of tiapride in digestive endoscopy (author's transl)]. / Intérêt du tiapride en endoscopie digestive.

Used in monotherapy in 20 patients as a premedication for a high digestive endoscopy, tiapride gave results quite comparable to those of substances used till now (anticholinergic, anxiolytic) with tolerance on the whole excellent.

[Primary intestinal lymphangiectasis or Waldmann's disease (author's transl)]. / Lymphangiectasie intestinale primitive ou maladie de Waldmann.

The authors report the observation of a primary intestinal lymphangiectasy diagnosed on a young girl sent for isolated edema of her inferior members, recently appeared. Clinical examination was normal. Biology found a low protein rate at 33 g/l and a low lymph rate : 183 L/mm3. Hepatic and renal records were normal. Test to marked albumin asserted the exsudative enteropathy with a fecal radio-activity of 3.6% (N 1%). Biopsy of the small intestines set out lymphangiectasies of the intestinal mucosa. Referring to this observation and to literature date, the authors realise a clinical and physiopathological analysis of Waldmann's disease or primary intestinal lymphangiectasy.