Biomimetic layer-by-layer templates for calcium phosphate biomineralization.

Carboxylated, sulfated and/or phosphorylated surfaces are admitted as potential optimal templates for biomimetic deposition of calcium phosphate (CaP) coatings in view of improving implants' osseointegration. Layer-by-layer films were built up consisting of anionic chondroitin sulfate (ChS), a biological carboxylated and sulfated polysaccharide and cationic poly(l-lysine) (PLL). The films were used as soft matrices to immobilize a model phosphoprotein, phosvitin (PhV). The respective roles of ChS, PLL and PhV terminal layers on the heterogeneous nucleation kinetics and the structure of CaP deposits obtained from supersaturated solutions were inspected. Critical supersaturation ratios and induction times preceding heterogeneous nucleation were precisely determined and interpreted within the framework of classical nucleation theory in order to derive the effective interfacial energies of CaP crystals. It was found that the potency of terminal layers toward CaP nucleation increased in the order: PLL

Computer aided surgery system for shoulder prosthesis placement.

The aim of this research is to provide a light and easy-handling shoulder model for surgeons in order to ease the preoperative and peroperative work required when replacing the shoulder joint with a prosthesis. The digital mock-up of the shoulder is simplified according to the criteria of the surgeon, allowing easy manipulation of the model for a virtual operation. The model can be parameterized from X-rays or CT images. This paper describes the method used to obtain a virtual mock-up that is useful for preoperative simulation. Furthermore, it is shown that a real-time augmented reality system could be achieved for peroperative application.

Thyroid disorders during interferon alpha therapy in 625 patients with chronic hepatitis C: a prospective cohort study.

AIM: to report the prevalence, risk factors, management and long-term outcome of thyroid disorders caused by INFalpha in patients with chronic hepatitis C. PATIENTS AND METHODS: From January 1991 to December 2004, 625 patients with chronic hepatitis C underwent INFalpha therapy. TSH assay was normal and antithyroperoxidase antibodies (anti-TPO) was performed before onset antiviral treatment; then TSH was performed every 2 months in all patients during therapy, and every 3 months after treatment. RESULTS: 58 patients developed thyroid disorder (8.9%). Mean age was 50.6+/-13 years; sex ratio: 1 M/2 F; the anti-TPO antibodies were positive before onset antiviral treatment in 9 patients (13.8%). 26 patients developed hypothyroidism (44.8%), 9 patients developed hyperthyroidism (15.5%) and among them 3 cases of Grave's disease. Biphasic thyroiditis occurred in 21 patients (36.2%), anti-TPO increase during treatment in 2 patients (3.5%) without hypothyroidism. The dysthyroidism was more frequent in risk in female gender (p<0.05) and in the group with positive antiTPO antibodies before treatment (p<0.02). CONCLUSION: Female gender and positive antiTPO antibodies are the predictive factors of development of the thyroid dysfunction during INFalpha therapy.

[Hepatitis C and diabetes mellitus: effect of diabetes on the course of the liver disease]. / Hépatite virale C et diabète: influence du diabète sur l'évolution de l'hépatopathie.

UNLABELLED: The prevalence of diabetes mellitus is higher in chronic hepatitis C than in hepatitis B, even without cirrhosis. OBJECTIVE: To study the host, specific viral factors associated with diabetes mellitus and the influence of diabetes mellitus on the intensity of steatosis and the severity of fibrosis. MATERIAL AND METHODS: The following data were collected in a cohort of 1249 patients with chronic hepatitis C established between December 1991 and June 2004: age, gender, body mass index (BMI). None of the patients were under treatment for their liver disease. Serum transaminase level and hepatitis C serology with search for viral RNA, viral load and genotype were obtained. The Metavir score, iron overload using the Perls score (0-4) and steatosis class (0-3) were determined on liver biopsies. RESULTS: Mean patient age was 52.5+/-10 years (56% male). Mean BMI was 24.6+/-24 kg/m2. Forty-three patients (17.2%) presented diabetes mellitus. The mean duration of their diabetes was 8.9 years. Genotype 1 predominated (60.4%) and mean viral load was 7.7x10(6) eq.v/ml. Steatosis was present in 69.7% of the diabetic patients versus 17% of the non-diabetic patients. Grade 2 fibrosis (F2) was observed in 32.5% of diabetic patients versus 29% in non-diabetic patients and F3, F4 in 73% of the diabetic patients versus 57% of the non-diabetic patients. Comparison between diabetic and non-diabetic patients demonstrated an absence of statistically significant difference (at 5%) between the groups for gender, viral load and genotype. Diabetic persons were older (58.7 years against 51 years) and liver biopsy revealed steatosis and fibrosis (F3, F4) more often in diabetic patients (69.7% versus 49.5%). CONCLUSION: These findings suggest that steatosis could favor progression of fibrosis in diabetics with chronic hepatitis C.

Adherence of osteoblast-like cells on calcospherites developed on a biomaterial combining poly(2-hydroxyethyl) methacrylate and alkaline phosphatase.

The polymer poly(2-hydroxyethyl) methacrylate (pHEMA) can copolymerize with alkaline phosphatase (AlkP) to form a hybrid material. The enzyme retains its biological activity and forms hydroxyapatite nodules (calcospherites) when polymer pellets are incubated with a synthetic body fluid. Osteoblast-like cells (ROS 17/2.8) were seeded on pellets of pHEMA and pHEMA-AlkP on which calcospherites were grown. They were examined by scanning electron microscopy (SEM) with backscattered electron imaging. Cell surface and shape were measured by image analysis combining the SEM images. Cells grown on pHEMA-AlkP had an increased surface area (449 +/- 216 microm(2) vs. 204 +/- 80 microm(2)). The number of filopodia anchoring the cells on the free polymer surface was reduced on pHEMA-AlkP, but numerous thick pseudopodia permitted a direct anchorage on the calcospherites. Pseudopodia were wider and longer than the filopodia. The backscattered images revealed that each cell was seated on 7.1 +/- 1.5 calcospherites and partially covered 10.3 +/- 1.9 others. Antifibronectin and anti-bone sialoprotein antibodies were used to investigate cell attachment. With confocal microscopy, both molecules were located at the interface between the cells and the mineral, inside the cells, and as free molecules on the calcospherites. Immunogold labeling was done with the same antibodies and examined with transmission electron microscopy (TEM). Adsorption of fibronectin and bone sialoprotein was noticeable at the cell/calcospherite interface and on the surface of the hydroxyapatite crystals. Immunogold studies revealed adhesion proteins (bone sialoprotein, fibronectin) to be present at the surface of crystals and at focal points of cell contact.