Cationic Polymeric Nanocapsules as a Strategy to Target Dexamethasone to Viable Epidermis: Skin Penetration and Permeation Studies

The present work aimed to evaluate the behavior of dexamethasone-loaded cationic polymericnanocapsules in hydrogels, regarding their in vitro drug release and skin drug retention and per- meation. Cationic polymeric nanocapsules prepared with Eudragit RS 100 as the polymeric wall had mean particle size of 139 +/- 3.6 nm, positive zeta potential (+11.38 +/- 1.7 mV), and high encapsulation efficiency (81 +/- 2%). After preparation, they were formulated as hydrogels, which showed non-Newtonian, plastic behavior, and acidic pH. Photon correlation spectroscopy analysis of these hydrogels demonstrated the presence of particles with mean particle size close to that of the original colloidal suspensions. The presence of dexamethasone-loaded nanocapsules in hydrogels promoted controlled drug release and an increase in the amount of drug delivered into viable epidermis, the main target tissue to topical glucocorticoid action. Moreover, the formulation did not increase the risk of drug penetration to dermis and permeation to the receptor compartment.

Control of Cell Attachment and Spreading on Poly(acrylamide) Brushes with Varied Grafting Density

To achieve spatial control of fibroblast cell attachment and spreading on a biocompatible polymer coating, the effect of poly(acrylamide) (PAAm) brushes with varied grafting density was investigated. The synthesis of the brushes was performed by surface-initiated atom transfer radical polymerization (SI-ATRP). Gold substrates were modified with binary self-assembled monolayers (SAMs) of an initiator and 16-mercaptohexadecanoic acid (MHDA) as an "inert" thiol to initiate the ATRP of AAm. By using different mixtures for the binary SAMs, a series of polymer brushes with varied grafting densities were prepared. The fractional coverage of surface bound initiator was determined by grazing incidence Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and contact angle measurements. A linear relationship between the Br/S ratio determined by XPS and ToF-SIMS versus the fraction of initiator on the surface determined by water contact angle measurements was observed. The varied initiation concentration on the gold substrates yielded PAAm brushes with different thicknesses, indicating a transition from mushroom to brush regimes with increasing grafting density. Thereby we achieved exquisite control of the degree of cell adhesion. Cell attachment experiments with NIH 3T3 fibroblast cells revealed cell spreading on PAAm brushes with low grafting densities (initiator fractional coverage <0.2) as well as a complete passivation by polymer brushes with higher grafting densities.

Combined Effect of Cryogel Matrix and Temperature-Reversible Soluble-Insoluble Polymer for the Development of in Vitro Human Liver Tissue

Hepatic cell culture on a three-dimensional (3D) matrix or as a hepatosphere appears to be a promising in vitro biomimetic system for liver tissue engineering applications. In this study, we have combined the concept of a 3D scaffold and a spheroid culture to develop an in vitro model to engineer liver tissue for drug screening. We have evaluated the potential of poly(ethylene glycol)-alginate-gelatin (PAG) cryogel matrix for in vitro culture of human liver cell lines. The synthesized cryogel matrix has a flow rate of 7 mL/min and water uptake capacity of 94% that enables easy nutrient transportation in the in vitro cell culture. Young's modulus of 2.4 kPa and viscoelastic property determine the soft and elastic nature of synthesized cryogel. Biocompatibility of PAG cryogel was evaluated through MTT assay of HepG2 and Huh-7 cells on matrices. The proliferation and functionality of the liver cells were enhanced by culturing hepatic cells as spheroids (hepatospheres) on the PAG cryogel using temperature-reversible soluble-insoluble polymer, poly(N-isopropylacrylamide) (PNIPAAm). Pore size of the cryogel above 100 μm modulated spheroid size that can prevent hypoxia condition within the spheroid culture. Both the hepatic cells have shown a significant difference (P < 0.05) in terms of cell number and functionality when cultured with PNIPAAm. After 10 days of culture using 0.05% PNIPAAm, the cell number increased by 11- and 7-fold in case of HepG2 and Huh-7 cells, respectively. Similarly, after 10 days of hepatic spheroids culture on PAG cryogel, the albumin production, urea secretion, and CYP450 activity were significantly higher in case of culture with PNIPAAm. The developed tissue mass on the PAG cryogel in the presence of PNIPAAm possess polarity, which was confirmed using F-actin staining and by presence of intercellular bile canalicular lumen. The developed cryogel matrix supports liver cells proliferation and functionality and therefore can be used for in vitro and in vivo drug testing.

Two-body wear simulation influence on some direct and indirect dental resin biocomposites - A qualitative analysis

PURPOSE

The aim of this study was to qualitatively assess the outcomes of two in vitro aging methods, thermal-cycling and twobody wear simulation accomplished with a dual-axis chewing device, on the surface characteristics of eight direct and indirect dental resin biocomposites.

METHODS

Eighty mesial-occlusal-distal dental cavities were restored with four direct nanohybrid composite materials and with four nano- and micro-hybrid lab-fabricated resin composite inlays. After the restored teeth were subjected to thermal-cycling and wear simulation based on mechanical loading, the surface texture features of the restorations were separately analysed for each of the methods, on epoxy resin models using a digital camera, computer-aided-design system, optical stereo-microscopy and scanning electron microscopy.

RESULTS

All the dental restorative resin based composites used in this investigation displayed different cyclic wear patterns after undergoing mechanical loading. After thermal-cycling, the group of resin composite inlays showed a better adaptation, a smoother and more polished occlusal surface compared with direct restorative materials. Only two of direct nanohybrid resin composites performed better after two aging methods. One nanohybrid and the other two microhybrid resin inlays did not perform as expected when they were subjected to simulated wear compared to the rest of test materials.

CONCLUSIONS

The use of the two-body wear simulation method revealed important information about the behavior of the dental resin-based composites when multiple oral factors are involved in a lab-simulated condition. Furthermore, the macro- and micro-morphological analysis showed different abrasion patterns among the materials being tested according to the filler percentage and distribution of the particles within the resin matrix.

[PERIFOCAL TISSUE REACTIONS TO IMPLANTATION OF THE SAMPLES OF HYDROGEL MATERIAL BASED ON POLYACRYLAMIDE WITH THE ADDITION OF THE CELLULOSE (AN EXPERIMENTAL STUDY)]

Tissue reactions to the grafting of samples of composite hydrogel based on polyacrylamide and cellulose of different origin (plant and bacterial) were studied in 48 laboratory outbred rats and 24 rabbits of chinchilla breed. The observations were carried out on Days 5, 14, 45 and 90 after placement of implants in the muscle, joint cavity, deep defects of the articular cartilage and subchondral bone. The study has revealed no migration and degradation of the samples. On Day 90, the signs of their biointegration (regardless of their nature) were detected in the muscles and in one case (the sample containing bacterial cellulose) in the cavity of the knee joint of the rat. The materials had good biocompatibility with muscle, cartilage and bone tissues, did not cause perifocal inflammation and effectively functioned as a prosthetic articular cartilage until the end of the study period.

Reduction of Candida biofilm adhesion by incorporation of prereacted glass ionomer filler in denture base resin

OBJECTIVES

This study investigated the influence of surface reaction-type prereacted glass ionomer (S-PRG) fillers on Candida albicans adhesion on denture base resin.

METHODS

Discs were prepared by incorporating the S-PRG filler into the polymer powder of a polymethyl methacrylate (PMMA)-based, heat-polymerizing resin at 0 (control), 5%, 10%, and 20% (w/w). The surface roughness of all disc surfaces was measured. Elemental analysis of released Na(+), Sr(2+), SiO3(2-), Al(3-), BO3(3-), and F(-) was performed after water immersion. Each disc was placed in a well with artificial saliva to form acquired pellicle, incubated, washed with phosphate-buffered saline, and immersed in a C. albicans (JCM2085) cell suspension standardized at 10(4) cells/ml. After aerobic incubation at 37 °C for 24 h, the metabolic mitochondrial activity, total biofilm biomass, and biofilm thickness were evaluated. The morphogenetic transition of C. albicans in the early culture stage (1 and 3 h) was observed.

RESULTS

There was a slight but significant increase in the surface roughness with an increase in the filler content. The metabolic activity and total biomass volume were significantly lower in all filler groups than in the control group, although there were no significant differences among the filler groups. Groups with at least 5% filler content exhibited a thinner biofilm compared with the control group. All filler groups showed hyphal forms at 3 h, with the length of the hyphae being lesser than those in the control group.

CONCLUSIONS

Although the incorporation of S-PRG filler slightly increases the surface roughness of denture base resin, it reduces the adhesion of C. albicans.

CLINICAL SIGNIFICANCE

The S-PRG filler has the potential to reduce Candida albicans adhesion on denture base resin and may lower the risk of denture stomatitis. However, filler incorporation can increase the surface roughness of heat-polymerizing denture base resin.

Evaluation of several flocculants for flocculating microalgae

Flocculation of microalgae with chitosan, polyacrylamide, Al2(SO4)3, NaOH and HNO3 was evaluated. Their flocculation efficiencies and optimal dosages were discussed. The effects of the flocculants on cells viability were also investigated and the cells were found to be intact during the flocculation process. Moreover, the effects of flocculants on the extractions were evaluated. Lipid content after flocculants treatments showed no significant differences. Carbohydrate content was lower but protein content was higher after NaOH treatment than those after other treatments. Furthermore, the five flocculated media maintained approximate growth yields to that of the fresh medium in microalgal cultivation, indicating the five flocculated media could be recycled, thereby reducing the cost of biodiesel production from microalgae. Finally, economic comparison of the flocculants was made and the cost of using HNO3, including flocculating cells and recycling medium, was found to be the lowest.

[Parathyreoidectomy in Rats Using Microsurgery and Medical Adhesive Sulfacrylate]

BACKGROUND

One of the main difficulties in assessing the effectiveness of etiologic treatment of hypoparathyroidism is absence of its standardized model.

OBJECTIVE

The aim of the study was to develop a method of hypoparathyroidism modeling.

METHODS

Controlled nonrandomized study was performed on female Wistar rats aged 10 month. Group 1 (n =14) was performed with destruction of parathyroid glands with electrocoagulation; group 2 (n =12)--parathyroidectomy by the developed method. In 3 and 14 days after the surgery the levels of ionized calcium, parathyroid hormone, number of white blood cells, blood leukocyte formula, indicators of immunological tests, histological examination of organs in the area of operations were performed. Statistical analysis was performed using the nonparametric Mann-Whitney-Wilcoxon test.

RESULTS

Selection of animals by sex and age criteria, angular skin incision, use of the operating microscope, microsurgical techniques, extirpation of parathyroid glands via resection of thyroid gland with the closure of the wound defect glue appeared to be the distinctive features of the developed method. In 14 days the group 2 showed decrease in ionized calcium (p = 0.016), PTH (p = 0.094), leucocytes (p = 0.004), PI (p = 0.003), spontaneous NBT test (p = 0.004), induced NBT test (p = 0.003) compared with group 1. Histological examination in the group 2 revealed no changes in thyroid gland, thin connective tissue capsule, cavity with a small amount of glue, however, there were determined foci of necrosis with perifocal inflammation in the group 1.

CONCLUSION

Combination of several techniques allowed to simulate metabolic disorders with persistent hypocalcemia as well as lack of mortality in early postoperative period.

[COMBINED ACRYLIC-POLYPROPYLEN REMOVABLE PROSTHESES FOR PROSTHODONTIC TREATMENT]

The article deals with the development of methods to prevent complications with prosthetic dentures patients with psychiatric status. The authors developed a method of manufacturing the denture using modern thermoplastic materials, the use of which in practice does not cause prosthetic stomatitis in patients with psychiatric status. The proposed methodology has been tested clinically. Based on Schiller- Pisarev and study fixation of prostheses has been shown the advantage of the prosthesis used for prosthetics partial dentition defects that can not be fixed prosthetics in this category of patients.

Effective Bone Regeneration Using Thermosensitive Poly(N-Isopropylacrylamide) Grafted Gelatin as Injectable Carrier for Bone Mesenchymal Stem Cells

In this study, thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) was grafted onto gelatin via atom transfer radical polymerization (ATRP). The chemical structure of PNIPAAm-grafted gelatin (Gel-PNIPAAm) was confirmed by XPS, ATR-IR, and (1)H NMR characterizations. Gel-PNIPAAm aqueous solution exhibited sol-to-gel transformation at physiological temperature, and was studied as injectable hydrogel for bone defect regeneration in a cranial model. The hydrogel was biocompatible and demonstrated the ability to enhance bone regeneration in comparison with the untreated group (control). With the incorporation of rat bone mesenchymal stem cells (BMSCs) into the hydrogel, the bone regeneration rate was further significantly enhanced. As indicated by micro-CT, histological (H&E and Masson) and immunohistochemical (osteocalcin and osteopontin) staining, newly formed woven bone tissue was clearly detected at 12 weeks postimplantation in the hydrogel/BMSCs treated group, showing indistinguishable boundary with surrounding host bone tissues. The results suggested that the thermosensitive Gel-PNIPAAm hydrogel was an excellent injectable delivery vehicle of BMSCs for in vivo bone defect regeneration.

Self-assembled microbubbles as contrast agents for ultrasound/magnetic resonance dual-modality imaging

In this work, superparamagnetic self-assembled microbubbles (SAMBs) consisting of "Poly(acrylic acid)-Iron oxide nanoparticles-Polyamine" sandwich-like shells and tetradecafluorohexane cores were fabricated by a template-free self-assembly approach. The SAMBs exhibit not only magnetic resonance (MR) T2 imaging functionality, but also ultrasound (US) image contrast, showing great potential as US/MR dual contrast agents. The diameters of the SAMBs can be tuned easily from 450nm to 1300nm by changing the precursor ratio, and this size variation directly affects their in vitro MRI and US signals. The SAMBs also exhibit in vivo contrast enhancement capabilities in rat liver with injection through portal vein, for both MR and US imaging. Additionally, the biodistribution of SAMBs over time suggests normal systemic metabolic activity through the spleen. The results show that the Fe content in rat liver reduces to a level of which Fe cannot be detected in 45days. The SAMBs exhibit no obvious damage to the primary organs of rat during the metabolic process, indicating their good biocompatibility in vivo.

Polyacrylamide gel substrates that simulate the mechanical stiffness of normal and malignant neuronal tissues increase protoporphyin IX synthesis in glioma cells

Protoporphyrin IX (PPIX) produced following the administration of exogenous 5d-aminolevulinic acid is clinically approved for photodynamic therapy and fluorescence-guided resection in various jurisdictions around the world. For both applications, quantification of PPIX forms the basis for accurate therapeutic dose calculation and identification of malignant tissues for resection. While it is well established that the PPIX synthesis and accumulation rates are subject to the cell’s biochemical microenvironment, the effect of the physical microenvironment, such as matrix stiffness, has received little attention to date. Here we studied the proliferation rate and PPIX synthesis and accumulation in two glioma cell lines U373 and U118 cultured under five different substrate conditions, including the conventional tissue culture plastic and polyacrylamide gels that simulated tissue stiffness of normal brain (1 kPa) and glioblastoma tumors (12 kPa). We found that the proliferation rate increased with substrate stiffness for both cell lines, but not in a linear fashion. PPIX concentration was significantly higher in cells cultured on tissue-simulating gels than on the much stiffer tissue culture plastic for both cell lines. These findings, albeit preliminary, suggest that the physical microenvironment might be an important determinant of tumor aggressiveness and PPIX synthesis in glioma cells.

Cationic polyacrylamide enhancing cellulase treatment efficiency of hardwood kraft-based dissolving pulp

Cellulase treatment for decreasing viscosity and increasing Fock reactivity of dissolving pulp is a promising approach to reduce the use of toxic chemicals, such as hypochlorite in the dissolving pulp manufacturing process in the industry. Improving the cellulase treatment efficiency during the process is of practical interest. In the present study, the concept of using cationic polyacrylamide (CPAM) to enhance the cellulase treatment efficiency was demonstrated. This was mainly attributed to the increased cellulase adsorption onto cellulose fibers based on the patching/bridging mechanism. Results showed that the cellulase adsorption was increased by about 20% with the addition of 250 ppm of CPAM under the same conditions as those of the control. It was found that the viscosity decrease and Fock reactivity increase for the cellulase treatment was enhanced from using CPAM. The CPAM-assisted cellulase treatment concept may provide a practical alternative to the present hypochlorite-based technology for viscosity control in the industry.

An international multi-centre prospective study on the efficacy of an intraarticular polyacrylamide hydrogel in horses with osteoarthritis: a 24 months follow-up

BACKGROUND

Polyacrylamide hydrogel (PAAG) was evaluated recently to treat osteoarthritis (OA) in horses with highly encouraging results; however no long term field-study was done to explore its clinical efficacy and lasting effect. The objective of this study was to evaluate the efficacy of PAAG in improving clinical signs of OA in horses. We hypothesized that lameness grade would significantly improve and the effect would last at least 2 years in osteoarthritic joints treated with PAAG. Forty three horses older than 2 years with OA in only one joint based on clinical evaluation, intra-articular anaesthesia and imaging (radiography) were included in this study. Horses were injected with 2 ml of PAAG into the affected joint and were followed up at 1, 3, 6, 12 and 24 months. Efficacy of PAAG was evaluated by blinded clinical assessment of lameness. Adverse reactions to joint injection were assessed. Data relating to case details, type of activity, joint and limb involved, lameness duration, lameness grading, previous joint treatment, joint effusion grading, radiographic grading, and owner assessment were recorded. Factors associated with the outcome measure "lameness grading" were analyzed using generalized linear mixed model for logistic regression.

RESULTS

At 1, 3, 6, 12 and 24 months follow-up, 59%, 69%, 79%, 81/% and 82.5% of horses were non-lame respectively. Reduction of joint effusion was observed over time. No side effect was observed in the treated joints. There was a significant decrease in lameness grade from baseline to 1, 3, 6, 12 and 24 months (P < 0.0001) and a significant positive association with joint effusion (P < 0.0001). Estimates for odds ratio (OR) showed that the effect of treatment increased over time (OR for lower lameness from month 1 to month 24 relative to baseline increased from 20 to 58).

CONCLUSIONS

PAAG significantly alleviated lameness and joint effusion in osteoarthritic joints. PAAG is a safe and lasting (at least 24 months) OA treatment in horses. PAAG is a promising new treatment for OA in horses.

Highly efficient antibacterial surface grafted with a triclosan-decorated poly(N-hydroxyethylacrylamide) brush

This work presented a highly efficient antibacterial Ti-surface which was grafted with poly(N-hydroxyethylacrylamide) (PHEAA) brush and further decorated with triclosan (TCS). The modified surfaces were characterized using contact angle measurements, X-ray photoelectron spectroscopy, and attenuated total reflectance Fourier transform infrared. The antibacterial performance of the modified surfaces was evaluated using the Streptococcus mutans and Actinomyces naeslundii attachment test. The Ti surface with PHEAA brush (Ti-PHEAA) was able to resist the adhesion of the bacteria, while the TCS-decorated Ti surface (Ti-TCS) showed the capability of killing the bacteria adhered on the surface. As we coupled the TCS to the PHEAA brush, the surface showed highly efficient antibacterial performance due to the combination of the resistance to the bacteria adhesion and its activity of killing bacteria.

Tissue elasticity regulated tumor gene expression: implication for diagnostic biomarkers of primitive neuroectodermal tumor

Background

The tumor microenvironment consists of both physical and chemical factors. Tissue elasticity is one physical factor contributing to the microenvironment of tumor cells. To test the importance of tissue elasticity in cell culture, primitive neuroectodermal tumor (PNET) stem cells were cultured on soft polyacrylamide (PAA) hydrogel plates that mimics the elasticity of brain tissue compared with PNET on standard polystyrene (PS) plates. We report the molecular profiles of PNET grown on either PAA or PS.

Methodology/Principal Findings

A whole-genome microarray profile of transcriptional expression between the two culture conditions was performed as a way to probe effects of substrate on cell behavior in culture. The results showed more genes downregulated on PAA compared to PS. This led us to propose microRNA (miRNA) silencing as a potential mechanism for downregulation. Bioinformatic analysis predicted a greater number of miRNA binding sites from the 3' UTR of downregulated genes and identified as specific miRNA binding sites that were enriched when cells were grown on PAA—this supports the hypothesis that tissue elasticity plays a role in influencing miRNA expression. Thus, Dicer was examined to determine if miRNA processing was affected by tissue elasticity. Dicer genes were downregulated on PAA and had multiple predicted miRNA binding sites in its 3' UTR that matched the miRNA binding sites found enriched on PAA. Many differentially regulated genes were found to be present on PS but downregulated on PAA were mapped onto intron sequences. This suggests expression of alternative polyadenylation sites within intron regions that provide alternative 3' UTRs and alternative miRNA binding sites. This results in tissue specific transcriptional downregulation of mRNA in humans by miRNA. We propose a mechanism, driven by the physical characteristics of the microenvironment by which downregulation of genes occur. We found that tissue elasticity-mediated cytokines (TGFβ2 and TNFα) signaling affect expression of ECM proteins.

Conclusions

Our results suggest that tissue elasticity plays important roles in miRNA expression, which, in turn, regulate tumor growth or tumorigenicity.

Methods for biomimetic remineralization of human dentine: a systematic review

This study aimed to review the laboratory methods on biomimetic remineralization of demineralized human dentine. A systematic search of the publications in the PubMed, TRIP, and Web of Science databases was performed. Titles and abstracts of initially identified publications were screened. Clinical trials, reviews, non-English articles, resin-dentine interface studies, hybrid layer studies, hybrid scaffolds studies, and irrelevant studies were excluded. The remaining papers were retrieved with full texts. Manual screening was conducted on the bibliographies of remaining papers to identify relevant articles. A total of 716 studies were found, and 690 were excluded after initial screening. Two articles were identified from the bibliographies of the remaining papers. After retrieving the full text, 23 were included in this systematic review. Sixteen studies used analogues to mimic the functions of non-collagenous proteins in biomineralization of dentine, and four studies used bioactive materials to induce apatite formation on demineralized dentine surface. One study used zinc as a bioactive element, one study used polydopamine, and another study constructed an agarose hydrogel system for biomimetic mineralization of dentine. Many studies reported success in biomimetic mineralization of dentine, including the use of non-collagenous protein analogues, bioactive materials, or elements and agarose hydrogel system.

Inhibition of the enhancement of infection of human immunodeficiency virus by semen-derived enhancer of virus infection using amyloid-targeting polymeric nanoparticles

The semen-derived enhancer of virus infection (SEVI) is a natural amyloid material that has been shown to substantially increase viral attachment and infectivity of HIV in cells. We previously reported that synthetic monomeric and oligomeric amyloid-targeting molecules could form protein-resistive coatings on SEVI and inhibit SEVI- and semen-mediated enhancement of HIV infectivity. While oligomeric amyloid-binding compounds showed substantial improvement in apparent binding to SEVI compared to monomeric compounds, we observed only a modest correlation between apparent binding to SEVI and activity for reducing SEVI-mediated HIV infection. Here, we synthesized amyloid-binding polyacrylate-based polymers and polymeric nanoparticles of comparable size to HIV virus particles (∼150 nm) to assess the effect of sterics on the inhibition of SEVI-mediated enhancement of HIV infectivity. We show that these polymeric materials exhibit excellent capability to reduce SEVI-mediated enhancement of HIV infection, with the nanoparticles exhibiting the greatest activity (IC50 value of ∼4 μg/mL, or 59 nM based on polymer) of any SEVI-neutralizing agent reported to date. The results support that the improved activity of these nanomaterials is likely due to their increased size (diameters = 80-200 nm) compared to amyloid-targeting small molecules and that steric interactions may play as important a role as binding affinity in inhibiting viral infection mediated by SEVI amyloids. In contrast to the previously reported SEVI-neutralizing, amyloid-targeting molecules (which required concentrations at least 100-fold above the Kd to observe activity), the approximate 1:1 ratio of apparent Kd to IC50 for activity of these polymeric materials suggests the majority of polymer molecules that are bound to SEVI contribute to the inhibition of HIV infectivity enhanced by SEVI. Such size-related effects on physical inhibition of protein-protein interactions may open further opportunities for the use of targeted nanomaterials in disease intervention.

Prevention of aggregation and renaturation of carbonic anhydrase via weak association with octadecyl- or azobenzene-modified poly(acrylate) derivatives

The prevention of aggregation during renaturation of urea-denatured carbonic anhydrase B (CAB) via hydrophobic and Coulomb association with anionic polymers was studied in mixed solutions of CAB and amphiphilic poly(acrylate) copolymers. The polymers were derivatives of a parent poly(acrylic acid) randomly grafted with hydrophobic side groups (either 3 mol % octadecyl group, or 1-5 mol % alkylamidoazobenzene photoresponsive groups). CAB:polymer complexes were characterized by light scattering and fluorescence correlation spectroscopy in aqueous buffers (pH 7.75 or 5.9). Circular dichroism and enzyme activity assays enabled us to study the kinetics of renaturation. All copolymers, including the hydrophilic PAA parent chain, provided a remarkable protective effect against CAB aggregation during renaturation, and most of them (but not the octadecyl-modified one) markedly enhanced the regain of activity as compared to CAB alone. The significant role of Coulomb binding in renaturation and comparatively the lack of efficacy of hydrophobic association was highlighted by measurements of activity regain before and after in situ dissociation of hydrophobic complexes (achieved by phototriggering the polarity of azobenzene-modified polymers under exposure to UV light). In the presence of polymers (CAB:polymer of 1:1 w/w ratio) at concentration ∼0.6 g L(-1), the radii of the largest complexes were similar to the radii of the copolymers alone, suggesting that the binding of CAB involves one or a few polymer chain(s). These complexes dissociated by dilution (0.01 g L(-1)). It is concluded that prevention of irreversible aggregation and activity recovery were achieved when marginally stable complexes are formed. Reaching a balanced stability of the complex plays the main role in CAB renaturation, irrespective of the nature of the binding (by Coulomb association, with or without contribution of hydrophobic association).

[Clinical examination of the gingival effects of three glass ionomer restorative materials (GC Fuji IX GP, GC Fuji IX GP EXTRA és GC EQUIA)]

The restoration of cervical abrasions, erosions or cervical carious lesions is still challenging because of their unpredictable adhesion and possible negative effects on the marginal plaque accumulation. The impact of three different glass ionomer cements (GIC) on the marginal gingiva and root sensitivity was studied. Furthermore, it was investigated in details, whether or not a recently developed light curing varnish (GC Coat - EQUIA) had any additional effect on the gingival tissue. A total number of 30 non-smokers with healthy gingiva having at least one cervical supra/paragingival abrasion/erosion/abfraction defects were enrolled in the present study. The cervical defects were randomly restored by using one of the three GIC and the gingival parameters were recorded and evaluated at baseline, 6 weeks and 6 months. According to our results root sensitivity were substantially decreased in all the three groups. Plaque scores were also reduced in all groups with the greatest improvement at the sites where the new varnish were applied. Although this improvement was not reflected by the gingival parameters, such as bleeding on probing and crevicular fluid flow, since both were slightly increased in the varnish group. However, neither the intra-group, nor the intergroup differences reached statistical significance. Consequently, the three investigated GIC did not significantly affect the gingival health, therefore they might serve as alternative for the treatment of such cervical lesions. Nevertheless, the new light cure varnish-coated GIC did not seem to be either clinically or statistical significantly more favorable.

[Features of adhesion of anaerobic periodontopathogenic bacteria and Candida albicans fungi to experimental samples of basis dental plastic depending on surface roughness and polishing method]

AIM

Study the main surface parameters of milled polyacrylic materials using atomic force microscopy and primary microbial adhesion of periodontopathogenic group bacteria and Candida albicans fungi taking into consideration the method of sample polishing.

MATERIALS AND METHODS

Studied samples: mill-treated without polishing (control); ergobox polished; polished in dental laboratory conditions; polished by a rubber brush in dentists' office. Microbial strains belonging to periodontopathogenic species (clinical isolates) that had been isolated from periodontal pockets of periodontitis patients: Porphyromonas gingivalis, Fusobacterium nucleatum, Streptococcus sanguis, C. albicans fungi were used for modelling experiments of primary adhesion of microbes to the material samples.

RESULTS

S. sanguis had the highest degree of adhesion to polymer after milling, P. gingivalis, C. albicans--medium, F. nucleatum--low. A significant reduction of adhesion is observed during polishing in dental laboratory conditions or ergobox, less significant--during polishing in dental office.

CONCLUSION

The data obtained allow to make a conclusion that the samples from polymer materials for preparation of prosthesis basis have varying degree of intensity of microbial adhesion of members of periodontopathogenic microflora and C. albicans fungi that depends on the polishing method, that accordingly determined the differences in colonization resistance against formation of microbial biofilm during polymer use in clinical conditions. . ,

Substrate stiffness together with soluble factors affects chondrocyte mechanoresponses

Tissue cells sense and respond to differences in substrate stiffness. In chondrocytes, it has been shown that substrate stiffness regulates cell spreading, proliferation, chondrogenic gene expression, and TGF-β signaling. But how the substrate stiffness together with soluble factors influences the mechanical properties of chondrocyte is still unclear. In this study, we cultured goat articular chondrocytes on polyacrylamide gels of 1, 11, and 90 kPa (Young's modulus), and measured cellular stiffness, traction force, and response to stretch in the presence of TGF-β1 or IL-1β. We found that TGF-β1 increased cellular stiffness and traction force and enhanced the response to stretch, while IL-1β increased cellular stiffness, but lowered traction force and weakened the response to stretch. Importantly, the effects of TGF-β1 on chondrocyte mechanics were potent in cells cultured on 90 kPa substrates, while the effects of IL-1β were potent on 1 kPa substrates. We also demonstrated that such changes of chondrocyte mechanoresponse were due to not only the changes of actin cytoskeleton and focal adhesion, but also the alteration of chondrocyte extracellular matrix synthesis. Taken together, these results provide insights into how chondrocytes integrate physical and biochemical cues to regulate their biomechanical behavior, and thus have implications for the design of optimized mechanical and biochemical microenvironments for engineered cartilage.

[Polyacrylates of noble metals as potential antitumor drugs]

The antitumor activity of polyacrylates of the noble metals containing argentum (argacryl), aurum (auracryl) and platinum (platacryl) has been studied using experimental murine solid tumor models (Lewis lung carcinoma and Acatol adenocarcinoma). It has been found that polyacrylates of the noble metals are capable of inhibiting tumor development by 50-90% compared to control. Auracryl that inhibites the growth of Lewis lung carcinoma and Acatol adenocarcinoma by 80 and 90%, respectively, compared to control is the most efficient among the tested compounds and can be recommended for the further profound preclinical studies.