Effects of various hyperbaric gas mixtures on metabolic parameters of human blood

Changes in metabolic parameters of healthy subjects were studied during experimental 4-to 21-day courses of simulated diving in hyperbaric normoxic (oxygen-helium), hyperoxic (oxygen-nitrogen-helium), and argon-containing gas mixtures with different oxygen contents. The blood concentrations of primary substrates and activity of enzymes were measured spectrophotometrically. In most cases, the clinical and biochemical parameters of the blood remained within normal clinical ranges and exhibited significant individual variations. Long-term simulated deep dives (>200 m) resulted in changes in lipid metabolism expressed as an increase in the plasma concentrations of triglycerides, low-density lipoproteins, and polyunsaturated fatty acids. No significant changes were found during experimental 70-m dives performed according to recompression treatment table with the use of a hyperoxic helium-containing gas mixture. In contrast, long-term exposure to a normoxic argon-containing mixture at a pressure of 5 msw caused a significant increase in the blood contents of triglycerides, total cholesterol, and glucose, as well as a smaller increase in the activities of several tissue enzymes. At the same pressure, hypoxic oxygen-nitrogen-argon and oxygen-nitrogen mixtures did not affect the majority of clinical and biochemical parameters examined. However, in some subjects, they increased the atherogenicity index, concentrations of triglycerides, and activities of lactate dehydrogenase and alkaline phosphatase. The absence of any pathological changes in clinical and biochemical parameters of the blood indicates that both gas mixtures are safe and can be used in barochambers. Episodic changes in lipid metabolism and enzyme activities observed in healthy subjects exposed to helium-and argon-containing gas mixtures can be interpreted as a reversible hepatic dysfunction due to the high pressure. The extent of the changes in the parameters of lipid metabolism in the blood is determined by the magnitude of the overpressure and the duration of the exposure.     

Long-term expansion of multipotent mesenchymal stromal cells under reduced oxygen tension

It has been shown that a decrease in oxygen tension during cultivation of multipotent mesenchymal stromal cells (MMSCs) caused a short-term decline in the proportion of CD73⁺ cells in the population, with no effect on the number of cells expressing the other constitutive surface markers (CD90, CD105). The heterogeneity of the cell population declined: large spread cells disappeared. The proliferative activity of MMSCs significantly increased and remained stable under conditions close to tissue oxygen levels (5% O₂). At lower oxygen concentration, it is gradually reduced from the third to fourth passages. The increase in proliferative activity was not accompanied by increased telomerase gene expression, which indicated that no cell transformation had occurred. Global gene expression analysis of MMSC gene expression revealed changes in expression of cyclins (CCND2, PCNA), regulatory subunit cyclin-dependent kinase (CKS2), and an inhibitor of cyclin-dependent kinases 4 and 6 (CDKN2C) regulating the cell cycle, which probably facilitated the proliferative activity of cells at lower oxygen tension.     

In vitro evaluation of crystalline silicon nanoparticles cytotoxicity

The effects of silicon-based nanoparticles on viability and cellular organelle state were evaluated in human lymphocytes in vitro. We did not find any changes in cell viability in experimental groups compared to control. Cell death occurred mainly due to apoptosis and late apoptosis, and necrosis/apoptosis ratio in the control and after exposure to nanoparticles remained unchanged. All silicon-based nanoparticles (Si, SiB, SiPd) caused an increase of reactive oxygen species in the cells. Evaluation of mitochondria and lysosomes state after interaction with modified nanoparticles demonstrated slight decrease in its function. Thus, modification of silicon nanoparticles did not significantly reduce their biocompatibility.     

Changes in the higher fatty acid composition of blood plasma and erythrocyte membranes during long exposure of a human to hyperbaric gas medium

The gas chromatographic method was used to study the changes in the fatty acid composition of the sum of the blood serum and erythrocyte membrane lipids in healthy male volunteers under the conditions of simulation in the ground-based hyperbaric set of long dives at depths of up to 350 m in the oxygen-helium and oxygen-neon media and in the readaptation period. At a depth of 100 m, a decrease in the serum content of the sum of saturated acids (palmitic (16:0)n and stearic (18:0) acids) and a 1.5-fold increase in the linoleic acid content compared to the background was found. A comparison of the individual changes in the blood serum and erythrocyte membrane fatty acids, as well as the unsaturation index (UI, the ratio of the sum of the unsaturated fatty acid concentrations multiplied by the number of double bonds in the molecule to the sum of the saturated fatty acid concentrations) and the R index (the erythrocyte to the serum fatty acid content ratio), showed that, under the experimental conditions and in the period of readaptation, the main changes occurred in the erythrocyte membranes, in which the unsaturated fatty acid content increased, and the linoleic and, especially, the arachidonic acid contents changed in different directions, depending on the depth of the dive. In the readaptation period, the linoleic and arachidonic acid contents decreased twofold on the first day and exceeded even the background level on the fourth day. The data obtained give evidence for the adaptive role of the erythrocyte membrane lipids upon exposure of humans to a hyperbaric medium with a changed gas composition.     

Interaction of human multipotential mesenchymal stromal and immune cells

Multipotential mesenchymal stromal cells (MMSCs) are the subject of increasing scientific interest due to their key role in physiological renewal and repair. Allogeneic MMSCs interaction with other components of tissue environment, in particular with immune cells, represent one of the most intriguing question of modern cell physiology. MMSCs possess pronounced immunomodulatory capabilities based on their "immmunopriveledge" properties and the ability to suppress immune response. This review is highlighted the current state of art in the field of MMSCs immunomodulatory effects realization and mechanisms. MMSCs and immune cells interaction represents complex multidirectional process governed by both direct cell-to-cell interactions and soluble factors (interferon-gamma, tumor necrosis factor, prostaglandin E2, hepatocyte growth factor, interleukins ets.). The importance of physical environmental factors, primarily oxygen tension, on peculiarities of MMSCs and immune cells interaction is discussed.     

Immunophenotype of human lymphocytes after interaction with mesenchymal stromal cells

Human multipotent mesenchymal stromal cells (MMSCs) were cocultured with allogenic blood-born mononuclear cells (MNCs). The MNCs consisted of cells that differed in their maturity or functional state, such as lymphocytes from adult peripheral blood vs. umbilical cord blood (cb) or nonstimulated vs. phytohemagglutinin (PHA)-activated lymphocytes from peripheral blood, respectively. The share of T, B, and natural killer (NK) cells or T cell subsets within the initial MNCs or cbMNCs were within physiological reference range for adult peripheral blood. After coculturing with the MMSCs, the populations of B cells decreased in both MNCs and cbMNCs, whereas the populations of the T and NK cells decreased among cbMNC only (p < 0.05). A decrease in the subset of T-NK cells was observed in the T cells of both MNCs and cbMNCs. In the coculture of MMSCs and PHA-MNCs, we found decrease in the number of CD8⁺ and HLA-DR⁺ cells and an increase in the number of CD25⁺ lymphocytes compared to monocultured PHA-MNCs. Our data show that the interaction with MMSCs did not substantially modify the composition of allogenic lymphocytes independent of their maturation (MNCs vs. cbMNCs) or activation (MNCs vs. PHA-MNCs), and the means were within the physiological limits. Moreover, exposure to the MMSCs did not reduce the viability of lymphocytes and even promoted the survival of cells in case of cbMNCs.     

Effects of microgravity simulation on the production of interleukins in culture of human mesenchymal stromal cells

The effects of microgravity that were simulated using clinoritation and cell exposure in a Random Positioning Machine (RPM; Dutch Space, Netherlands) on the production of interleukins by mesenchymal stromal cells (MSCs) of the human bone marrow were studied. Additionally, interleukins production was studied in osteogenic derivatives of MSCs induced by growth factors, such as 10⁻⁸ M dexamethasone, 0.2 mM ascorbic acid, and 10 mM β-glycerolphosphate. Twenty-day clinoritation resulted in an increase in the interleukin-8 (IL-8) level by a factor of 1.4–3.2 in the culture medium of MSCs and their osteogenic derivatives. Exposure of cells to RPM was followed by an increase in IL-8 production by factors of 1.5–6 and 1.6–2.1 after 10 and 20 days of the treatment, respectively. MSCs and their osteogenic derivatives exhibited a tendency towards a decrease in the release of IL-6 into the culture medium after simulation of microgravity with RPM. Thus, in different models, microgravity modified production of interleukins in MSCs and mature cells with the osteogenic phenotype.     

西藏墨脱格当乡野生虎捕食家畜现状与保护建议

曾经在西藏东南的阔叶林中广泛分布的孟加拉虎,目前仅有一个小种群残留在墨脱县境内。2000年5－6月间,在大型家畜遭受野生虎捕食最严重的墨脱县格当乡展开调查,试图寻找减轻虎害的方法。结果表明：1994－1995年虎的捕食率达到最高,对牛和骡马的捕食率分别是17．9％和9．4％;但1996年后,捕食率分别降低到7．8％和1．8％,这可能与1996年当地曾捕杀过一头虎有关。1993－1999年间,全乡牛的数量下降了11％,但骡马数量上升了23％,这是因为当地为增加运输能力而从别处购得骡马。据反映,目前格当乡境内大约有4－5头虎。1997年和1999年,均见母虎和小虎同行,说明该种群尚有繁殖。在抽样的21户居民家中,1999年4月到2000年5月间,66．6％的人家有大型牲畜遭虎捕杀,共损失牛27头,马12匹,而自1993年以来,21户中共有18户（85．8％）,有牲畜被杀记录,共计损失117头。其中对牛的捕食率达19．7％,对马达11．9％,平均每户损失牛1．2头,骡马0．5匹。非法狩猎减少了虎的猎物如野猪、羚牛等的数量,是老虎转向家畜的主要原因之一。虎害已对格当乡群众的经济造成较大负面影响。但格当乡以及周边地区保护着中国最后的野生孟加拉虎种群,为确保虎的长期生存同时减少人－虎冲突,建议改变目前放牧方式,尽可能联合放牧、增加看护;改善放牧地条件,清除牧场周围蕨草丛;减少对羚牛等有蹄类的猎杀,以减少对老虎猎物种群的破坏;对部分家畜移入棚内试行圈养,既保护家畜,又提高乳制品产量和增加农家肥料;实行多种经营方法,建议养一些山羊和家禽;政府应该帮助安置好部分愿意外迁的居民,这样既满足这些居民的需要,同时也减轻对当地野生动物种群的压力。