Controllability of brushite structural parameters using an applied magnetic field.

The paper studies the influence of low intensity static magnetic field on brushite structural and microstructural parameters using the X-ray diffraction and the transmission electron microscopy. This effect was shown to have various influences on DCPD (Dicalcium Phosphate Dihydrate) structure depending on a magnetic field configuration or time of synthesis, which allows achieving controllability of the main properties of an obtained material. The influence of the magnetic field leads mostly to the decrease of crystallite sizes with no impact on the crystal lattice parameters. In (0 2 0) and (1 5 0) planes the growth of crystallite sizes is observed after 2 and 3 days of crystallization, respectively. The analysis of different contributions to peak broadening in [0 b 0] direction showed a similar trend for the crystallite sizes with the lower lattice microstrains after 2 days of synthesis. The effect similar to the preferred orientation was observed and classified with the Harris method.

Haemostatic chitosan coated gauze: in vitro interaction with human blood and in-vivo effectiveness.

BACKGROUND: Chitosan and its derivates are widely used for biomedical application due to antioxidative, anti-inflammatory, antimicrobial and tissue repair induced properties. Chitosan-based materials also used as a haemostatic agent but influence of different molecular weight and concentration of chitosan on biological response of blood cells is still not clear. The aim of this research was to evaluate interaction between human blood cells and various forms of chitosan-based materials with different molecular weight and chitosan concentration and prove their effectiveness on in-vivo model. METHODS: We used chitosan with molecular weight 200, 500 and 700 kDa and deacetylation rate 80-82 %. For chitosan impregnation of gauze chitosan solutions in 1 % acetic acid with different concentrations (1, 2, 3, 5 %) were used. We used scanning electron microscopy to obtain information about chitosan distribution on cotton surface; Erythrocyte agglutination test and Complete blood count test - for evaluation of interaction between blood cells and chitosan-based materials with different compound. In-vivo studies was performed in 20 Wistar rats to evaluate effectiveness of new dressing. RESULTS: Our data shown that chitosan can bind erythrocytes in concentration-depend manner that does not depend on its molecular weight. In addition, chitosan-based materials affect selectively human blood cells. Composition of chitosan with cotton materials does not change erythrocyte shape and does not cause agglutination. CONCLUSIONS: Сotton-chitosan materials have higher adhesive properties to platelets that depend on molecular weight and concentration of chitosan. These materials also change platelets' shape that probable is one of the most important mechanisms of haemostatic effect. In-vivo studies have shown high effectiveness of 2 % 200 kDa chitosan for stop bleeding from arteries of large diameter.

Rare case of pathological biomineralization of eye tissue.

The authors have described the case of pathological biomineralization of ocular posterior chamber. Histological examination of affected eye shells revealed inflammation, oedema, dyscirculatory violations, and signs of dystrophic calcification. Structural-phase and chemical analyses of calcification have revealed that the biomineral consists of hydroxyapatite with relatively small crystallite size and defective crystal lattice. In the described case the formation of pathological biomineral in the vision organ was initiated by penetrating wound. Eye injury might have caused a hemophthalmus and chronic inflammatory reaction in the shells, these processes eventually led to the organ subatrophy and to the development of dystrophic and necrobiotic changes in the tissues. Pathological biomineralization in the affected organ developed as a type of dystrophic calcification.Key words: eye, pathological biomineralization, hydroxyapatite.

Silver-doped hydroxyapatite coatings formed on Ti-6Al-4V substrates and their characterization.

Coatings with antibacterial components for medical implants are recommended to reduce the risk of bacterial infections. Therefore hydroxyapatite (HA) coatings with addition of chitosan (CS) and silver (Ag) are proposed in this work in an attempt to resolve this problem. Ti-6Al-4V substrates were modified by a chitosan film to study the influence of surface modification on the formation of the HA-Ag and HA-CS-Ag coatings. Using a thermal substrate method, HA and HA-CS coatings doped with Ag(+) were prepared at low substrate temperatures (90°C). Coated surfaces were examined using X-ray diffraction and scanning electron microscopy. The amount of silver in the deposited coatings was analyzed by atomic absorption spectroscopy. From this study it is concluded that the substrate surface modified by a chitosan film promotes the coating formation and increases the antibacterial activity of produced coatings against a strain of Escherichia coli. The adhesion of E. coli (ATCC 25922) to sheep erythrocytes was decreased by 14% as compared with the reference samples without Ag. It could be explained by the inhibition of bacterial adhesins by Ag(+) ions released. The combined action of silver ions and chitosan resulted in a 21% decrease in adhesive index.

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.

A study of brushite crystallization from calcium-phosphate solution in the presence of magnesium under the action of a low magnetic field.

The paper discusses the crystallization of dicalcium phosphate dehydrate (DCPD) with subsequent transformation to nanocrystalline hydroxyapatite (НA) under the permanent magnetic field in the presence of magnesium. It was found that the presence of magnesium in the initial solution in concentrations of 0.01-0.03g/l decreased the crystallinity of calcium-phosphates. The precipitation of DCPD under the magnetic field of 0.3T was carried out in proximity of the north and south magnetic poles. The differences in the particle morphology and structure of precipitates with the same phase composition (DCPD) were observed in the neighborhood of the north and the south pole. Lattice parameters of DCPD precipitates obtained biomimetically near opposite magnet poles were calculated using XRD results. It was found that the increased crystallization time (more than 3days) leads to a complete attenuation of DCPD peaks, whereas НА peaks are still present.