Experimental evaluation of new chitin-chitosan graft for duraplasty.

Natural materials such as collagen and alginate have promising applications as dural graft substitutes. These materials are able to restore the dural defect and create optimal conditions for the development of connective tissue at the site of injury. A promising material for biomedical applications is chitosan-a linear polysaccharide obtained by the deacetylation of chitin. It has been found to be nontoxic, biodegradable, biofunctional and biocompatible in addition to having antimicrobial characteristics. In this study we designed new chitin-chitosan substitutes for dura mater closure and evaluated their effectiveness and safety. Chitosan films were produced from 3 % of chitosan (molar mass-200, 500 or 700 kDa, deacetylation rate 80-90%) with addition of 20% of chitin. Antimicrobial effictively and cell viability were analysed for the different molar masses of chitosan. The film containing chitosan of molar mass 200 kDa, had the best antimicrobial and biological activity and was successfully used for experimental duraplasty in an in vivo model. In conclusion the chitin-chitosan membrane designed here met the requirements for a dura matter graft exhibiting the ability to support cell growth, inhibit microbial growth and biodegradade at an appropriate rate. Therefore this is a promising material for clinical duroplasty.

STRUCTURAL CHANGES IN SUBMANDIBULAR SALIVARY GLAND, CAUSED BY HEAVY METAL SALTS, AND THEIR CORRECTION WITH DIALIPON (EXPERIMENTAL STUDY).

Setting of possibilities of structural changes correction in submandibular salivary gland with a Dialipone drug, caused by adverse effect of heavy metals salts on an organisms of different age group rats. Structural changes and their correction were studied on the histological preparations basis painted by hematoxylin-eozin, Van-Gizon, PAS reaction, investigated and photographed by means of the digital image display system "SEO Scan". In comparison to the results of submandibular salivary gland tissue histological research of animals without any correction of microelementosis, animals that took Dialipone are marked with a better glandular epithelium saving, less widespreading of dystrophic and dyscirculatory changes, sclerotization processes in stroma. When comparing of Dialipone restoration possibilities, it was set, that different age group animals show different application efficiency of the corrector. The rats of young and mature age have more complete renewal of structural changes. The rats of advanced age show worse reparative capabilities, less complete and effective renewal of structural changes.

[In-vitro degradation of the chitosan membranes under various syntheses conditions].

The hydrolytic degradation of polymer films, which were obtained by application of 2% and 3% chitosan solutions in 1% acetic acid on a base sheet has been investigated. As the solvent was removed, these firms were either treated with 0.5% NaOH for 3 min or with phosphate buffer (рН 8) for 10 min. The degrees of degradation for the obtained samples were studied during 1-96 h in solutions with pH values of 5.0, 7.0 and 8.5. The results revealed resistance of the films within the first 6 h, followed by their subsequent degradation. The rate of degradation depended on pH of the solution, chitosan percentage and the treatment methods of films. The materials with the initial chitosan content of 3% were more resistant to the hydrolytic degradation, but the decreasing in pH accelerated the weight loss of the film. However, if the membranes were treated with phosphate buffer, the rate and degree of sample degradation were slowed down. Thus, the results are considered as a basis for the further development of biomaterials to treat the skin surface damages.

Morphogenetic aspects of biomineralization on the background of benign prostatic hyperplasia.

Despite the considerable spread of pathological prostate inclusions their nature and significance in the development of gland pathology are not established exactly. The work includes histological research of 628 surgical biopsies of benign prostatic hyperplasia, the sections were stained with hematoxylin and eosin or Congo red, von Kossa methods. Mineral constituent of prostatoliths (5 cases) was studied by infrared spectroscopy (IRS); scanning electron microscopy with X-ray microanalysis (REMMA/EDX), transmission electron microscopy and electron diffraction (TEM/ED). The average age of the operated patients was 69,5±0,42 years old. In 88,22±1,67% of cases nodular prostatic hyperplasia was combined with diffuse or focal inflammation, engorgements of prostate gland secretion were observed in 81,76±2,97%. In the lumen of the prostate gland corpora amylacea were detected in 64,72±1,13% of cases, in 27,6±3,48% - concreations. There was a significant strong correlation between inflammation and calculi - r = 0.93 (p<0,05), inflammation and secret engorgement - r=0,95 (p<0,05), engorgement and concreations - r = 0,88 (p <0,05). TEM results show the same morphological type of prostatolith crystals and their small size (tens of nanometers), that indicates their preferential formation by direct sedimentation from the liquid phase, rather than the appearance and maturation of corpora amylacea on the surface. Based on the received data, the dominant mechanism of concrements formation is precipitation by direct sedimentation of prostate secretions, but it's not a dystrophic calcification of the corpora amylacea. Mineral component of prostatic concrements is carbonate bioapatite with a minor inclusion of other chemical elements.