Ra-226 in building materials as a source of indoor radon in high-rise residential buildings in Russian cities.

The problem of indoor radon in high-rise buildings is mostly associated with exhalation from building materials. Characterization of the radon entry from building materials by diffusion is required to provide a proper control of the population indoor radon exposure. To analyze the relationship between the content of Ra-226 in building materials and the indoor radon concentration the results of the following surveys in high-rise buildings in Russian cities were used: 1) indoor radon (>1000 apartments), 2) natural radionuclides in the building materials in existing buildings by means of non-destructive field gamma spectrometry (100 apartments). The surveys were carried out in nine large cities in different climatic zones. The radon entry rate due to diffusion from building materials, D, normalized to Ra-226 activity concentration, Ra, is in the range of 0.2-0.6 (Bq/m3/h)/(Bq/kg), depending on the type of building materials and building construction. In new multi-story buildings, the typical D/Ra ratio can be assumed to be 0.4 (Bq/m3/h)/(Bq/kg). In new energy-efficient buildings, the ratio of the radon concentration to Ra-226 activity concentration is on average 2.1 times higher than in multi-story buildings of lower energy efficiency built before 2000. The average radon exhalation rate from the building materials, normalized to Ra-226 activity concentration, is estimated to be 0.25 Bq/m2/h.

Relationship between Ra-226 activity concentration in building materials and indoor radon concentration: An example of Russian high-rise residential buildings.

The worldwide trend toward the construction of high-rise buildings with high energy efficiency highlights the role of building materials as a source of indoor radon in the modern urban environment. The aim of the study is to analyze the relationship between the Ra-226 activity concentration in building materials and indoor radon concentration using the example of multi-story buildings in Ekaterinburg. Measurements of the activity concentration of natural radionuclides in building materials were carried out using a new non-destructive method. A radon survey conducted early provided the data on indoor radon concentrations in the same apartments. The obtained Ra-226 activity concentrations in building materials in high-rise buildings were found to be relatively low, ranging from 9.1 to 51 Bq/kg. The typical radon entry rate by diffusion from building materials for modern Russian multi-story buildings can be accepted as equal to 0.5 Bq/(m3∙h) per 1 Bq/kg of Ra-226 activity concentration. Ra-226 in building materials has been shown to be a primary source of indoor radon in modern high-rise buildings, where this factor can cause indoor radon concentrations above the reference level of 100 Bq/m3 at low air exchange rates. The activity concentration of Ra-226 in building materials should be considered a separate parameter for regulation within the national radiation protection systems.

[Models of bone defects in rabbits used to evaluate the bone graft materials efficacy]. / Modeli kostnykh defektov u krolikov, ispol'zuemye dlya otsenki effektivnosti kostno-plasticheskikh materialov.

The review deals with the main types of experimental models of bone defects of the skull in rabbits. The information about the types of critical defects, methods of their modeling and the possibilities of application of the described models in the studies of bone graft materials in dentistry and maxillofacial surgery is systematized.

[Advantages and disadvantages of bone graft materials activated by BMP-2 and constructs carrying its gene]. / Preimushchestva i nedostatki kostno-plasticheskikh materialov, aktivirovannykh BMP-2 i nesushchimi ego gen konstruktsiyami.

In the review gene constructs and proteins used to impart osteoinductive properties to bone graft materials are compared. On the basis of clinical and experimental data the experience and prospects of their application in maxillofacial surgery and dentistry are described. Information about complications associated with the use of bone morphogenetic protein-2 (BMP-2) and vectors carrying its gene is provided.

[Treatment options for external inflammatory root resorption]. / Sposoby lecheniya naruzhnoi vospalitel'noi rezorbtsii kornya zuba.

THE AIM OF THE STUDY: Was to compare the efficacy of various treatment options for external inflammatory root resorption according to literature data. MATERIALS AND METHODS: Literature was searched in electronic databases «eLibrary¼ and «PubMed¼ for key words «external inflammatory resorption treatment¼, «external inflammatory resorption management¼. Inclusion criteria comprised publications in Russian or English, clinical and experimental studies, full description of treatment protocol and obtained results. Studies with no full text, describing root resorption of orthodontic origin, clinical cases and clinical case series were excluded from the study. RESULTS: The problem of external inflammatory root resorption is poorly described in the Russian scientific literature. There are no registered protocols for its prevention and treatment or therapeutic agents with proved efficacy available in Russia. The only accessible approach for external inflammatory root resorption remains timely pulp extirpation after dental trauma which importance is underlined by all authors involved in the field of dental trauma studies. MTA and calcium hydroxide being popular as intracanal medications still have significant inconveniences as they potentially provoke root dentine fractures or replacement resorption. CONCLUSION: There is a need for elaboration and implementation of new prevention and treatment options for external inflammatory root resorption after dental trauma.

[Relative survival and cell adhesion of multipotent mesenchymal cells from primary teeth pulp on the surface membranes and sponges produced from collagen]. / Otnositel'naya vyzhivaemost' i adgeziya mul'tipotentnykh mezenkhimal'nykh kletok iz pul'py molochnykh zubov na poverkhnosti membran i gubok, proizvodimykh iz kollagena.

OBJECTIVE: To study the behavior of SHED cell culture on different types of materials for the regeneration of periodontal tissues with different porosity. MATERIAL AND METHODS: Porous collagen material Fibro-Gide (Geitstlich Pharma AG, Switzerland), designed to increase the volume of the gum and the barrier collagen membrane Bio-Gide (Geitstlich Pharma AG, Switzerland) were studied in vitro on SHED cultures. As a control sample, a Spongostan sponge made of gelatin (Johnson & Johnson Medical, UK) with the most pronounced porosity and wettability was used. Acute cytotoxicity was determined using a screening method for assessing the number of living cells in a sample (MTT test). SHED cells were sown on the materials to study the attachment of cells to materials and their migration inside the samples. Before seeding, the cells were stained with vital fluorescent dye PKH26 (red fluorescent cell linker kit, Sigma, Germany) for further visualization. RESULTS AND DISCUSSION: Using the MTT test it was shown that they do not have cytotoxic effects. At the same time by the 8th day of the experiment in the presence of Fibro-Gide and Bio-Gide the cells showed an increase in proliferative activity by 19% and 12%, respectively compared with the control group. The cells attached and spread out on the surface of the materials and migrated into the thickness of porous Fibro-Gide and Spongostan. CONCLUSION: The in vitro study showed that the most favorable material for SHED cell culture is the collagen material Fibro-Gide with sufficient porosity, elasticity and hydrophilicity. SHED cells attach to the collagen matrix and easily penetrate into the sample, filling the entire internal space, while the proliferative capacity of the cell culture increases.

Development prospects of curable osteoplastic materials in dentistry and maxillofacial surgery.

The article presents classification of the thermosetting materials for bone augmentation. The physical, mechanical, biological, and clinical properties of such materials are reviewed. There are two main types of curable osteoplastic materials: bone cements and hydrogels. Compared to hydrogels, bone cements have high strength features, but their biological properties are not ideal and must be improved. Hydrogels are biocompatible and closely mimic the extracellular matrix. They can be used as cytocompatible scaffolds for tissue engineering, as can protein- and nucleic acid-activated structures. Hydrogels may be impregnated with osteoinductors such as proteins and genetic vectors without conformational changes. However, the mechanical properties of hydrogels limit their use for load-bearing bone defects. Thus, improving the strength properties of hydrogels is one of the possible strategies to achieve the basis for an ideal osteoplastic material.

[New directions of immunocorrection in multiple sclerosis]. / Novye napravleniia immunokorrektsii pri rasseiannom skleroze.

Multiple sclerosis is a central nervous system disease with autoimmune and neurodegenerative mechanisms of development. This disease can lead to severe disability and neurological defects. Although its etiology and pathogenesis remain unclear, research data show that multiple sclerosis is a multifactorial disease, the development of which depends on environmental factors, as well as a genetic predisposition. The impact of these factors lead to the death of neural cells, accompanied by demyelination of nerves and neuronal dysfunction. Therapy of multiple sclerosis is based on the use of anti-inflammatory and immunomodulating substances, however, there are certain disadvantages associated with the constant use of these drugs and a possible change in dosage over time. This review discusses the pathogenesis of multiple sclerosis and the role of various subpopulations of immune cells in the development of diseases, as well as existing approaches to therapy. It is noted that immunoreconstitution therapy has advantages over immunomodulation and immunosuppression maintenance therapy for some patients. Thus, short courses of therapy provide more adequate treatment for patients and lower risks of adverse events associated with chronic immunosuppression. The review also discusses the data of clinical studies on the immunoreconstitution therapy drugs, such as alemtuzumab, ocrelizumab and cladribine. It is noted that nowadays the exact mechanisms underlying this type of therapy remain unclear. In this regard, further studies are needed to explain the therapeutic effects. It is assumed that patients with a high risk of multiple sclerosis progression are the optimal group of patients for the early use of selective immunoreconstitution therapy. Thus, immunoreconstitution therapy may be the treatment of choice for many patients with highle active multiple sclerosis.

Determination of radionuclide composition of the Russian NPPs atmospheric releases and dose assessment to population.

Original data on radionuclide activities in air emissions of Russian NPPs are presented based on direct on-site measurements in vent stacks of NPPs during an extensive survey in 2017-2018. For the first time, the detailed inventories of radionuclides in the air releases were directly measured for all types of nuclear reactors, employed in the Russian NPPs. Based on the results of measurements, annual doses for local populations around the Russian NPPs were estimated. The technogenic radionuclides, detected in the air emissions, were ranked according to their contribution in the annual dose. 14C is the major contributor for the annual dose from the atmospheric releases of LWGR reactors - almost 98% for Bilibino NPP's EGP-6 reactor, and up to 86% for RBMK-1000 reactors (Smolensk NPP). For PWR reactors (VVER) contribution to the annual dose from atmospheric releases is formed mostly by tritium, 14C and noble gases. Estimated annual doses for local populations in the vicinity of the Russian NPPs do not exceed 10-5 Sv/year. Atmospheric releases of 60Co, 134Cs, 137Cs and other aerosols, involved in the routine monitoring programs of Russian NPPs, do not contribute significantly to the annual dose. Based on these results, 14C and tritium will be included in the monitoring programs of atmospheric release control at all Russian NPPs; maximal permissible levels of annual releases for 14C and tritium will be established since 2019.

[Safety and efficacy of BMP-2 and BMP-7 use in dentistry]. / Bezopasnost' i éffektivnost' primeneniia morfogeneticheskikh belkov kosti 2 i 7 v stomatologii.

The article deals with bone morphogenetic proteins BMP-2 and BMP-7 with high osteoinductive potential. The materials containing these proteins are considered. Their safety and efficacy for regeneration of maxillofacial bone defects are evaluated. The prospects of bone tissue regeneration technologies development based on the use of bone morphogenetic proteins are described.

[Biocompatibility and osteoinductive properties of collagen and fibronectin hydrogel impregnated with rhBMP-2]. / Biosovmestimost' i osteogennye svoistva kollagen-fibronektinovogo gidrogelya, impregnirovannogo BMP-2.

The study aimed to demonstrate the biocompatibility and osteoinductive properties of a hydrogel based on highly purified collagen and fibronectin impregnated with rhBMP-2. In vitro and in vivo experiments have shown that the minimum effective dosage of rhBMP-2 is 10 µg/ml. The cytocompatibility of the collagen-fibronectin gel was determined using MTT test and staining with PKH-26. There was no inflammation reaction when the material was subcutaneously implanted in rats (n=30) in vivo. The collagen-fibronectin hydrogel containing 10 µg/ml rhBMP-2 showed high osteogenic properties. By the end of 28 days 8±4% of its volume was replaced by newly formed bone tissue in case of subcutaneous implantation, 17±10% in intramuscular implantation and 26±11% in intraosseous implantation in the calvarial critical-size. The optimal combination of biocompatible and osteogenic properties of collagen-fibronectin hydrogel impregnated with BMP-2 allows us to consider it as a promising basis for creating the new generation of osteoplastic materials for dentistry.

[Chitosan hydrogels biocompatibility improvement with the perspective of use as a base for osteoplastic materials in dentistry]. / Povyshenie biosovmestimosti khitozanovykh gidrogelei s perspektivoi ikh ispol'zovaniya v kachestve osnovy dlya kostno-plasticheskikh materialov v stomatologii.

Using chitosan as the basis for osteoplastic material, we were dealt with its low biocompatibility. The critical assessment of it is poorly presented in the literature and does not have systematic approaches to solving. The aim of the study was to determine the effect of factors affecting chitosan charge and its free amino groups number on the biocompatibility of hydrogels. Biocompatibility of chitosan compositions were studied in male Wistar rats (n=90). The subcutaneous implantation of chitosan discs and hydrogel caused abundant leukocyte infiltration. The addition of ß-glycerophosphate followed by dialysis slightly reduced the inflammatory response. Treatment with a solution of alkali NaOH and NaHCO3 buffer, on the contrary, intensified the inflammatory response. It is confirmed the effect of charged amino groups of chitosan on leukocyte taxis A decrease in the deacetylation degree (DD) of chitosan to 39.0% led to a statistically significant decrease in leukocyte infiltration. Saturation of chitosan hydrogels with PLA granules reduced by 16% the level of leukocyte infiltration, which was supposedly associated with a decrease in the volume of the hydrogel and an increase in the area of its interaction with blood plasma proteins, which reduce the positive charge of chitosan. The most significant reduction in leukocyte infiltration was achieved with a combination of deacetylated to 39.0% chitosan hydrogel with the addition of 16% by weight highly porous PLA granules.

[The prospects of collagen as a basis for curable and activated osteoplastic materials]. / Perspektivy ispol'zovaniia kollagenovogo gidrogelia v kachestve osnovy dlia otverzhdaemykh i aktivirovannykh kostno-plasticheskikh materialov.

In the review, the structure and biological properties of collagen, variants of its production from natural sources and purification are considered. Methods for modifying the physico-mechanical properties of collagen to create a curable, highly purified collagen hydrogel are described. The advantages of a cured highly purified collagen hydrogel as a basis for osteoplastic material and a means of delivery of growth factors are indicated. The registered osteoplastic materials based on the curable highly purified collagen hydrogel are described, and their comparative analysis is carried out. On the basis of the obtained data, a conclusion was made about the prospects of using collagen as a basis for curable and activated osteoplastic materials.

[Differences in the cytocompatibility of bone-plastic materials from xenogeneic hydroxyapatite with stem cells from human exfoliated deciduous teeth and adipose tissue-derived mesenchymal stem cells]. / Razlichiia tsitosovmestimosti kostno-plasticheskikh materialov iz ksenogennogo gidroksiapatita s mul'tipotentnymi mezenkhimal'nymi stromal'nymi kletkami, poluchennymi iz pul'py vypavshikh molochnykh zubov i podkozhnogo lipoaspirata.

AIM: To compare the cytocompatibility of osteoplastic materials used in dentistry with stem cells from human exfoliated deciduous teeth (SHED) and adipose tissue-derived mesenchymal stem cells (AD-MSC). MATERIAL AND METHODS: Materials of the brands 'Bio-Oss', 'Indost', 'Bioplast', 'Viscoll' and 'Trikafor' were selected for study purposes. Cultures of SHED and AD-MSC were used for testing. The cytotoxic effect of the materials was determined using MTT test and vital staining with trypan blue. Cell adhesion was assessed by the vital staining of PKH-26. RESULTS: Water extracts of bone-plastic materials from xenogeneic hydroxyapatite of the brands 'Bio-Oss', 'Indost' and 'Bioplast' exert a cytotoxic effect on SHED and do not cause the death of AD-MSC. Materials based on collagen and ß-tricalcium phosphate possess high cytocompatibility with all cell cultures under study. CONCLUSION: From the point of cytocompatibility all the examined bone-plastic materials may be considered safe for the restoration of bone defects. It should be noted that SHED transplantation on the surface of materials containing xenogeneic hydroxypatite is unacceptable.

IMMUNOGENIC PROPERTIES OF RECOMBINANT MOZAIC PROTEINS BASED ON ANTIGENS NS4A AND NS4B OF HEPATITIS C VIRUS.

The aim of the study was to investigate immunogenic properties of mosaic recombinant proteins constructed on the data of hepatitis C virus NS4A and NS4B antigens. Four mosaic recombinant proteins, containing the T and B epitopes of the NS4A and NS4B antigens, were created by genetic engineering methods in the E. coli system. To enhance the immune response they were linked in different variations to the nucleotide sequences of murine interleukin-2 (IL-2), the Neisseria meningiditis lipopeptide, and the T helper epitope of the core protein of hepatitis C virus. The immunogenic properties of these recombinant proteins were analyzed by immunoblotting, ELISA and ELISpot using sera from immunized mice and patients infected with hepatitis C virus. Recombinant proteins specifically reacted with the sera of immunized mice and infected patients in immunoblotting. According to the ELISA data, the predominant formation of antibodies to NS4B was observed when mice were immunized with the recombinant proteins containing both antigens. Analysis of gamma-interferon production by T-lymphocytes upon contact with activated dendritic cells showed in ELISpot that the maximum production of this cytokine was detected when adjuvant components were located at the N- and C-ends of the recombinant protein. The highest level of gamma-interferon production during stimulation with this drug was detected in lymphocytes from the bone marrow and lymph nodes. The recombinant protein containing the T and B epitopes of NS4A and NS4B, murine IL-2 and the lipopeptide Neisseria meningiditis had the greatest immunostimulate effect among the four constructions. This recombinant protein formed nanoparticles of 100-120 nm in size.

[The prospects of hydrogels usage as a basis for curable osteoplastic materials]. / Perspektivy ispol'zovaniia gidrogelei v kachestve osnovy dlia otverzhdaemykh kostno-plasticheskikh materialov.

The article deals with the main types of the polymers used in hydrogel preparation. Their biological, physical and chemical properties was compared. Ways of polymers hardening and prospects of medical application were considered. The prospect of use of chitosan hydrogels activated by osteoinductors as a material for bone augmentation were concluded.

[Molecular epidemiological analysis of HIV-1 in Kazakhstan in 2009-2013].

In this study pol gene analysis of 205 HIV-1 samples collected in Kazakhstan in 2009 and 2012-2013 was carried out. CRF02_AG variant is dominating in Almaty and actively circulates in East Kazakhstan Province. IDU-A variant is dominating in the rest of Kazakhstan. The data on low prevalence (3%) of HIV drug resistance mutations in native patients were obtained.

Low air exchange rate causes high indoor radon concentration in energy-efficient buildings.

Since 1995, requirements on energy-efficient building construction were established in Russian Building Codes. In the course of time, utilisation of such technologies became prevailing, especially in multi-storey building construction. According to the results of radon survey in buildings constructed meeting new requirements on energy efficiency, radon concentration exceeds the average level in early-constructed buildings. Preponderance of the diffusion mechanism of radon entry in modern multi-storey buildings has been experimentally established. The experimental technique of the assessment of ventilation rate in dwellings under real conditions was developed. Based on estimates of average ventilation rate, it was approved that measures to increase energy efficiency lead to reduction in ventilation rate and accumulation of higher radon concentrations indoors. Obtained ventilation rate values have to be considered as extremely low.

Mechanisms and sources of radon entry in buildings constructed with modern technologies.

To investigate the influence of modern building construction technologies on the accumulation of radon indoor, 20 rooms in buildings constructed using mostly monolithic concrete or aerated concrete blocks have been studied. Dominance of the diffusion mechanism of radon entry in buildings constructed with modern technologies has been established. As a result of computer simulations it was found that the main contribution to the variability of radon concentration was made by changes in the ventilation rate. At a low ventilation rate (<0.2 h(-1)) radon concentration above 200 Bq m(-3) can be observed for residential buildings. There is a need for the regulation of the radium-specific activity in building materials. According to the estimates of this study, the content of 226Ra in building materials should not exceed the value of 100 Bq kg(-1).

Indoor radon problem in energy efficient multi-storey buildings.

Modern energy-efficient architectural solutions and building construction technologies such as monolithic concrete structures in combination with effective insulation reduce air permeability of building envelope. As a result, air exchange rate is significantly reduced and conditions for increased radon accumulation in indoor air are created. Based on radon survey in Ekaterinburg, Russia, remarkable increase in indoor radon concentration level in energy-efficient multi-storey buildings was found in comparison with similar buildings constructed before the-energy-saving era. To investigate the problem of indoor radon in energy-efficient multi-storey buildings, the measurements of radon concentration have been performed in seven modern buildings using radon monitoring method. Values of air exchange rate and other parameters of indoor climate in energy-efficient buildings have been estimated.