Samples of skin, tendons, muscles, and knitwear composed of NiTi wire are studied by uniaxial cyclic tension and stretching to rupture. The metal knitted mesh behaves similar to a superelastic ...material when stretched, similar to soft biological tissues. The superelasticity effect was found in NiTi wire, but not in the mesh composed of it. A softening effect similar to biological tissues is observed during the cyclic stretching of the mesh. The mechanical behavior of the NiTi mesh is similar to the biomechanical behavior of biological tissues. The discovered superelastic effects allow developing criteria for the selection and evaluation of mesh materials composed of titanium nickelide for soft tissue reconstructive surgery.
Coatings based on calcium phosphate with thicknesses of 0.5 and 2 μm were obtained by high-frequency magnetron sputtering on NiTi substrates in an argon atmosphere. The coating was characterized ...using X-ray diffraction, scanning electron microscopy, atomic force microscopy, and in vitro cytocompatibility and bioactivity studies. A biphasic coating of tricalcium phosphate (Ca
(PO
)
) and hydroxyapatite (Ca
(PO
)
(OH)
) with a 100% degree of crystallinity was formed on the surface. The layer enriched in calcium, phosphorus, and oxygen was observed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Scanning electron microscopy showed that the surface structure is homogeneous without visible defects. The 2 µm thick coating obtained by sputtering with a deposition time of 4 h and a deposition rate of 0.43 µm/h is uniform, contains the highest amount of the calcium phosphate phase, and is most suitable for the faster growth of cells and accelerated formation of apatite layers. Samples with calcium phosphate coatings do not cause hemolysis and have a low cytotoxicity index. The results of immersion in a solution simulating body fluid show that NiTi with the biphasic coating promotes apatite growth, which is beneficial for biological activity.
At present, the use of alternative systems to replenish the lost functions of hepatic metabolism and partial replacement of liver organ failure is relevant, due to an increase in the incidence of ...various liver disorders, insufficiency, and cost of organs for transplantation, as well as the high cost of using the artificial liver systems. The development of low-cost intracorporeal systems for maintaining hepatic metabolism using tissue engineering, as a bridge before liver transplantation or completely replacing liver function, deserves special attention. In vivo applications of intracorporeal fibrous nickel–titanium scaffolds (FNTSs) with cultured hepatocytes are described. Hepatocytes cultured in FNTSs are superior to their injections in terms of liver function, survival time, and recovery in a CCl4-induced cirrhosis rats’ model. 232 animals were divided into 5 groups: control, CCl4-induced cirrhosis, CCl4-induced cirrhosis followed by implantation of cell-free FNTSs (sham surgery), CCl4-induced cirrhosis followed by infusion of hepatocytes (2 mL, 107 cells/mL), and CCl4-induced cirrhosis followed by FNTS implantation with hepatocytes. Restoration of hepatocyte function in the FNTS implantation with the hepatocytes group was accompanied by a significant decrease in the level of aspartate aminotransferase (AsAT) in blood serum compared to the cirrhosis group. A significant decrease in the level of AsAT was noted after 15 days in the infused hepatocytes group. However, on the 30th day, the AsAT level increased and was close to the cirrhosis group due to the short-term effect after the introduction of hepatocytes without a scaffold. The changes in alanine aminotransferase (AlAT), alkaline phosphatase (AlP), total and direct bilirubin, serum protein, triacylglycerol, lactate, albumin, and lipoproteins were similar to those in AsAT. The survival time of animals was significantly longer in the FNTS implantation with hepatocytes group. The obtained results showed the scaffolds’ ability to support hepatocellular metabolism. The development of hepatocytes in FNTS was studied in vivo using 12 animals using scanning electron microscopy. Hepatocytes demonstrated good adhesion to the scaffold wireframe and survival in allogeneic conditions. Mature tissue, including cellular and fibrous, filled the scaffold space by 98% in 28 days. The study shows the extent to which an implantable “auxiliary liver” compensates for the lack of liver function without replacement in rats.
A new approach to fabricate TiNi surfaces combining the advantages of both monolithic and porous materials for implants is used in this work. New materials were obtained by depositing a porous TiNi ...powder onto monolithic TiNi plates followed by sintering at 1200 °C. Then, further modification of the material surface with a high-current-pulsed electron beam (HCPEB) was carried out. Three materials obtained (one after sintering and two after subsequent beam treatment by 30 pulses with different pulse energy) were studied by XRD, SEM, EDX, surface profilometry, and by means of electrochemical measurements, including OCP and EIS. Structural and compositional changes caused by HCPEB treatment were investigated. Surface properties of the samples during their storage in saline for 10 days were studied and a model experiment with cell growth (MCF-7) was carried out for the unmodified sample with an electron beam to detect cell appearance on different surface locations.
This study aims to look into the applicability of a porous TiNi-based shape memory alloy (SMA) scaffold as an incubator for bone marrow mesenchymal cells, hepatocytes, and pancreatic islet cells. The ...porous TiNi-based SMA used was fabricated using a self-propagating high-temperature synthesis (SHS) technique, in which scaffold blocks measuring 4 × 4 × 10 mm were prepared. In vitro tests were done using mesenchymal stem cells (MSC) isolated from mature bone marrow of CBA/j inbred mice, and cultured in 3 different culture media - Control medium, Osteogenic medium, and Chondrogenic medium. Hepatocytes and islet cells were isolated from the livers and pancreatic glands of Wistar rats respectively, seeded on porous TiNi-based SMA scaffolds, and cultured. The scaffolds were then implanted into the abdominal cavity of Wistar rats and later harvested, at days 7, 14, 21, and 28, post-implantation. SEM imaging was performed with pre-implanted scaffolds at day 0 and harvested scaffolds at days 7, 14, 21, and 28, post-implantation. Based on weight increase percentages, the in vitro study revealed that the osteogenic group showed a 2-fold increase, and the chondrogenic group showed a 1.33-fold increase, compared to the control group. The in vivo study, on the other hand, showed that from day 7 post-implantation, the cellular in-growth gradually invaded the inner porous structure from the periphery towards the center, and at day-28 post-implantation, all pores were closed and completely filled with cells and the extracellular matrix. The results show that porous TiNi-based SMA is a unique biocompatible incubator for cell cultures and can be successfully used for tissue bioengineering and artificial organs.
Structural properties of porous TiNi-based materials produced by SHS method and sintering have been investigated. The material having different pore wall surface topography, porosity and pore size ...distribution was shown to be produced depending on the powder metallurgy method for porous TiNi-based alloy. All the materials having porosity of 55-70%, mean pore size 90-150 μm, as well as normal pore size distribution are most preferable. Ultimate strength and breaking point were determined to depend on porosity, pore size distribution, pore intersections and phase chemical composition of the material. Strength properties of the sintered alloy are twice as much compared to the SHS-produced ones due to homogeneity of its macrostructure, low chemical heterogeneity and TiNi3 precipitations strengthening the TiNi matrix.
This study looked into the synthesis and study of Dextrane Sulfate-Doxorubicin Nanoparticles (DS-Dox NP) that are sensitive to amylase and show anticoagulant properties. The particles were obtained ...by the method of solvent replacement. They had a size of 305 ± 58 nm, with a mass ratio of DS:Dox = 3.3:1. On heating to 37 °C, the release of Dox from the particles was equal to 24.2% of the drug contained. In the presence of amylase, this ratio had increased to 42.1%. The study of the biological activity of the particles included an assessment of the cytotoxicity and the effect on hemostasis and antitumor activity. In a study of cytotoxicity on the L929 cell culture, it was found that the synthesized particles had less toxicity, compared to free doxorubicin. However, in the presence of amylase, their cytotoxicity was higher than the traditional forms of the drug. In a study of the effect of DS-Dox NP on hemostasis, it was found that the particles had a heparin-like anticoagulant effect. Antitumor activity was studied on the model of ascitic Zaidel hepatoma in rats. The frequency of complete cure in animals treated with the DS-Dox nanoparticles was higher, compared to animals receiving the traditional form of the drug.
Introduction: The study of the pharmacokinetics of glucocorticosteroids is often required to solve fundamental and applied tasks of pharmacology. HPLC methods based on ultraviolet detection are ...attractive due to their availability, but their sensitivity is low enough to study in vivo kinetics. In this study, we propose a method for the determination of dexamethasone in biological objects, based on the use of HPLC with UV detection and having sufficient sensitivity to determine the drug in biological media (blood and periarticular tissues).
Materials and methods: Extraction of dexamethasone from biosamples was carried out by liquid-liquid extraction with acetone in an acidic medium using atenolol as an internal standard. The analysis was carried out on a Kromasil-100 C18 column. A mixture of methanol with phosphate buffer in the ratio 50÷50, pH=5.6 was used as the mobile phase. Detector - UV, wavelength - 254 nm. The LLOQ of the method was 50 ng/mL; the calibration curve demonstrated linearity in the con-centration range of 50-1000 ng/mL.The method was used to detect the medicinal product in peri-synovial tissues of rats with an autoimmune arthritis model.
Results: This study demonstrated that intraarticular injection of the liposomal form of dexamethasone, compared with its water-soluble form, allows maintaining the active concentration of the product in the joint and periarticular tissues for a longer time, which creates prerequisites for enhancing its therapeutic effect.
Conclusion: The proposed method provides a sensitive and specific approach for measuring dexamethasone in biological samples, such as blood and periarticular tissues. Preliminary findings indicate that the liposomal form of dexamethasone may exhibit better pharmacokinetic properties than the water-soluble form, which could lead to improved therapeutic outcomes.
Introduction: The study of the pharmacokinetics of glucocorticosteroids is often required to solve fundamental and applied tasks of pharmacology. HPLC methods based on ultraviolet detection are ...attractive due to their availability, but their sensitivity is low enough to study in vivo kinetics. In this study, we propose a method for the determination of dexamethasone in biological objects, based on the use of HPLC with UV detection and having sufficient sensitivity to determine the drug in biological media (blood and periarticular tissues). Materials and methods: Extraction of dexamethasone from biosamples was carried out by liquid-liquid extraction with acetone in an acidic medium using atenolol as an internal standard. The analysis was carried out on a Kromasil-100 C18 column. A mixture of methanol with phosphate buffer in the ratio 50÷50, pH=5.6 was used as the mobile phase. Detector - UV, wavelength - 254 nm. The LLOQ of the method was 50 ng/mL; the calibration curve demonstrated linearity in the con-centration range of 50-1000 ng/mL.The method was used to detect the medicinal product in peri-synovial tissues of rats with an autoimmune arthritis model. Results: This study demonstrated that intraarticular injection of the liposomal form of dexamethasone, compared with its water-soluble form, allows maintaining the active concentration of the product in the joint and periarticular tissues for a longer time, which creates prerequisites for enhancing its therapeutic effect. Conclusion: The proposed method provides a sensitive and specific approach for measuring dexamethasone in biological samples, such as blood and periarticular tissues. Preliminary findings indicate that the liposomal form of dexamethasone may exhibit better pharmacokinetic properties than the water-soluble form, which could lead to improved therapeutic outcomes.
SPATIAL AND TEMPORAL PATTERNS OF AIR TEMPERATURE CHANGES IN RUSSIA IN THE 20th CENTURY AND EARLY 21st CENTURY Анисимов, О. А., Государственный гидрологический институт, oleg@oa7661.spb.edu, Россия, 199053 С.-Петербург, 2-я линия В. О., д. 23; Anisimov, O. A., State Hydrological Institute, oleg@oa7661.spb.edu, 23, Vtoraya liniya, V. O., 199053 St. Petersburg, Russia; Жильцова, Е. Л., Государственный гидрологический институт, , Россия, 199053 С.-Петербург, 2-я линия В. О., д. 23 ...
Проблемы экологического мониторинга и моделирования экосистем,
2/2016
Journal Article
Анализ рядов приземной температуры воздуха на 744 метеостанциях России и сопредельных стран показал, что потепление климата в начале и в конце XX века обладало выраженными региональными ...особенностями. Начало процесса потепления не было одновременным на всей рассматриваемой территории. В данной работе исследована пространственная связанность поля температуры и выделены 15 регионов на территории России с синхронными изменениями на протяжении последних 35 лет. Для них были рассчитаны среднерегиональные тренды сезонных и среднегодового значений температуры воздуха в 1976-2009 гг. На основе количественных статистических критериев были также рассчитаны начальные годы современного изменения климата для каждой из метеостанций и построено их распределение по территории России. Полученные результаты дают возможность уточнить оценки уровня и пространственно-временной структуры современного потепления на территории России.
Аnalysis of series of the surface air temperature from 744 weather stations in Russia and neighboring countries showed that climate warming in the early and late 20th century had distinct regional patterns. The start of the warming process was not simultaneous at various parts of the territory. We studied spatial correlations of the surface air temperature, identified 15 regions with coherent changes over the past 35 years within the territory of Russia, and calculated the average regional trends of the seasonal and mean annual temperatures in 1976-2009. Statistical criteria for identification of the beginning of the recent climate change were applied to the data from meteorological stations, and then the spatial distribution over Russia was plotted. The results obtained give an opportunity to improve the estimates of the level and spatiotemporal distribution of the recent warming over the Russian territory.
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