DETERMINATION OF BIOCOMPATIBILITY AND CYTOTOXICITY OF POROUS TITANIUM-BASED MATERIALS IN EXPERIMENT

Aim - to evaluate the proliferative activity of dermal fibroblast cultures in the presence of composite materials based on titanium silicides in vitro. Materials and methods. To assess the proliferative activity of dermal fibroblasts in vitro, the following materials were used: titanium silicide, titanium carbosilicide oxidized in vacuum and without vacuum, titanium VT-00 (comparison group). Testing of proliferative activity was carried out by the direct contact method. The proliferation index, the doubling time and the number of culture doubling during the cultivation period were calculated. Attachment of dermal fibroblasts to the surface of the test materials and their presence on it during cultivation was assessed by scanning electron microscopy. Results. The study of the morphofunctional characteristics of dermal fibroblasts cultured in the presence of the test samples of material showed that during the entire experiment no major changes occurred in any of the series, the cells retained the monolayer growth characteristic of fibroblasts, preferably spindleshaped with 2-4 shoots. Moreover, all cultures of dermal fibroblasts underwent the same number of doublings during the experiment and reached saturation density 7 days after sowing, which indicates good proliferative activity of cells in the presence of test materials. The results of scanning electron microscopy demonstrate the high affinity of human dermal fibroblasts for both titanium silicide and titanium carbosilicides. Conclusion. Absence of morphofunctional changes in dermal fibroblasts and active proliferation testify to the absence of cytotoxicity of the investigated alloys, and the ability of cells to adhere to the surface of materials indicates their good biocompatibility

REVIEW OF MATERIALS AND TECHNOLOGICAL METHODS USED IN THE MANUFACTURE OF ENDOPROSTHESIS IN TRAUMATOLOGY AND ORTHOPAEDICS

Traumas and diseases of the musculoskeletal system are the second among the causes of temporary disability of the population, and the third among the causes of disability and mortality. An effective method of treatment is endoprosthetics. ; Every year across the globe 500-1000 patients per 1 million of population require prosthetics. The development of endoprostheses is progressing in various spheres: design of the implant parts, methods of fixation, use of various materials, different types of surface finish of implants. Endoprostheses that are currently produced and used in traumatology and orthopaedics are unified, i.e. ; standardized - all of them have different size, but their shape is the same. This imposes serious limitations on the use of implantation in difficult clinical cases. The way out can be the use of personified implants, designed and manufactured with the use of modern rapid prototyping technologies. In this case, the use of titanium will fully implement the most important advantages of this direction: the best biocompatibility, high corrosion resistance, low modulus of elasticity, high specific strength and endurance

PERSONIFIED APPROACH IN SURGICAL TREATMENT OF BENIGN BONE TUMORS WITH THE USE OF PRE-OPERATIVE COMPUTER PLANNING AND NAVIGATION

Aim - to analyze the results of the use of 3D modeling and computer navigation in the treatment of benign tumors and tumor-like diseases of long bones. Materials and methods. The study included 19 patients with benign tumors and tumor-like diseases. The main group consisted of 10 patients. In the preoperative planning stage, in addition to X-ray and computed tomography these patients had 3D-models of the affected bone segment constructed. Surgical treatment was carried out with the use of the navigation system. The control group consisted of 9 patients who underwent radiography and computed tomography of the affected bone segment in the preoperative planning stage. Results. The application of the new method made possible to reduce the operation time by 40 min, intraoperative blood loss by 350 ml, and the intensity of pain on a visual analog scale by more than 2 points. This result was achieved by intuitively simple for the operator dimensional orientation in the operative field in real time, the possibility of more accurate surgical procedures due to a more precise calculation of the level of necessary transplant. It minimizes the trauma of the donor area, exerting a positive influence on the reduction of postoperative pain. Conclusion. The use of 3D modeling and computer navigation for the treatment of patients with benign tumors and tumor-like diseases of long bones managed to improve noticeably the results of surgical treatment, and consequently, to speed up social and functional adaptation of patients and to enhance social and economic outcome

Diarylethene moiety as an enthalpy-entropy switch: photoisomerizable stapled peptides for modulating p53/MDM2 interaction

Analogs of the known inhibitor (peptide pDI) of the p53/MDM2 protein–protein interaction are reported, which are stapled by linkers bearing a photoisomerizable diarylethene moiety. The corresponding photoisomers possess significantly different affinities to the p53-interacting domain of the human MDM2. Apparent dissociation constants are in the picomolar-to-low nanomolar range for those isomers with diarylethene in the “open” configuration, but up to eight times larger for the corresponding “closed” isomers. Spectroscopic, structural, and computational studies showed that the stapling linkers of the peptides contribute to their binding. Calorimetry revealed that the binding of the “closed” isomers is mostly enthalpy-driven, whereas the “open” photoforms bind to the protein stronger due to their increased binding entropy. The results suggest that conformational dynamics of the protein-peptide complexes may explain the differences in the thermodynamic profiles of the binding

High-field Faraday rotation in II-VI-based semimagnetic semiconductors

The effects of d-d exchange interaction have been studied by measuring high-field Faraday rotation in II-VI-based semimagnetic semiconductors. For Cd1-xMnxTe crystals with x = 0.43 and at room temperature a saturation in magnetic field dependence of the Faraday rotation has been observed. In the case of low temperature (T = 4.2 K) and low Mn content (x = 0.05), two steps for Cd1-xMnxTe and one step for Cd1-xMnxSe have been found on this dependence. These steps are interpreted by the nearest-neighbour cluster model. The evaluated exchange constant J(NN) is in agreement with direct magnetization measurements. Peculiarity of high-field Faraday rotation in Fe-and Co-based semimagnetic semiconductors has been discussed. (C) 1998 Elsevier Science B.V. All rights reserved