Environmental drivers of increased ecosystem respiration in a warming tundra.

Arctic and alpine tundra ecosystems are large reservoirs of organic carbon1,2. Climate warming may stimulate ecosystem respiration and release carbon into the atmosphere3,4. The magnitude and persistency of this stimulation and the environmental mechanisms that drive its variation remain uncertain5-7. This hampers the accuracy of global land carbon-climate feedback projections7,8. Here we synthesize 136 datasets from 56 open-top chamber in situ warming experiments located at 28 arctic and alpine tundra sites which have been running for less than 1 year up to 25 years. We show that a mean rise of 1.4 °C [confidence interval (CI) 0.9-2.0 °C] in air and 0.4 °C [CI 0.2-0.7 °C] in soil temperature results in an increase in growing season ecosystem respiration by 30% [CI 22-38%] (n = 136). Our findings indicate that the stimulation of ecosystem respiration was due to increases in both plant-related and microbial respiration (n = 9) and continued for at least 25 years (n = 136). The magnitude of the warming effects on respiration was driven by variation in warming-induced changes in local soil conditions, that is, changes in total nitrogen concentration and pH and by context-dependent spatial variation in these conditions, in particular total nitrogen concentration and the carbon:nitrogen ratio. Tundra sites with stronger nitrogen limitations and sites in which warming had stimulated plant and microbial nutrient turnover seemed particularly sensitive in their respiration response to warming. The results highlight the importance of local soil conditions and warming-induced changes therein for future climatic impacts on respiration.

Thawing Yedoma permafrost is a neglected nitrous oxide source.

In contrast to the well-recognized permafrost carbon (C) feedback to climate change, the fate of permafrost nitrogen (N) after thaw is poorly understood. According to mounting evidence, part of the N liberated from permafrost may be released to the atmosphere as the strong greenhouse gas (GHG) nitrous oxide (N2O). Here, we report post-thaw N2O release from late Pleistocene permafrost deposits called Yedoma, which store a substantial part of permafrost C and N and are highly vulnerable to thaw. While freshly thawed, unvegetated Yedoma in disturbed areas emit little N2O, emissions increase within few years after stabilization, drying and revegetation with grasses to high rates (548 (133-6286) µg N m-2 day-1; median with (range)), exceeding by 1-2 orders of magnitude the typical rates from permafrost-affected soils. Using targeted metagenomics of key N cycling genes, we link the increase in in situ N2O emissions with structural changes of the microbial community responsible for N cycling. Our results highlight the importance of extra N availability from thawing Yedoma permafrost, causing a positive climate feedback from the Arctic in the form of N2O emissions.

[PECULIARITIES OF IMMUNE PROFILE IN BLOOD OF RATS IN THE DYNAMICS OF IMMOBILIZATION STRESS ON THE BACKGROUND OF HYPOTHYROIDISM].

The aim of our study was to investigate the peculiarities of changes in the indices of cellular and humoral immunity in the case of immobilization stress, which is implemented against the background of hypothyroidism. It was used 84 white Wistar male rats to study the peculiarities of the stress reaction against hypothyroidism. The study of cellular and humoral immunity was performed on a Beckman Coulter Epics-XL flow cytometer. During the immobilization stress in rats, the cellular immunity indices reliably decrease at the anxiety stage with adaptation to the effect of stress after 48 h in the resistance stage with subsequent exhaustion of the adaptation reserves at the depletion stage. Against the background of a decrease in the T-lymphocyte level at the anxiety stage, the B-lymphocyte population significantly increased (by 26.5%). In animals with deficiency of iodine-containing thyroid hormones, we noted a significant decrease in cellular and humoral immunity at all stages of immobilization stress, which was accompanied by a significant decrease of immunoregulatory index (p<0.05).

THE INFLUENCE OF MONOSODIUM GLUTAMATE ADMINISTRATION ON GENERATION OF REACTIVE OXYGEN SPECIES AND APOPTOSIS OF BLOOD LEUKOCYTES IN RATS.

The use of food additives in food manufacturing has been a public health issue for many years. Currently, more than 3000 food additives have been approved and estimates has shown that each person may consume 3.6 to 4.5 kg of food additives per year on average. One of the most common food additives in Ukraine and in Europe is monosodium glutamate (MSG). This paper reports the effect of monosodium glutamate administration at "safe" (allowed) doses on the generation of reactive oxygen species and apoptosis in leukocyte blood suspension of rats. Experimental studies were conducted on 32 non-linear, male, white rats weighing 180-200 g. The experimental animals were administered MSG (Sigma-Aldrich, USA) at a dose of 15, 30 and 45 mg/kg body weight. Control group of animals received normal saline. We have found that consumption of MSG at low dosage was associated with development of excessive reactive oxygen species generation and apoptotic processes in blood leukocytes of rats. Therefore it is advisable not only to investigate the established dangerous doses of E621, but also to study the molecular mechanisms of the "safe" (allowed) doses of MSG effect on a living organism.

THE INDICES OF ENDOGENOUS INTOXICATION IN RATS WITH CARRAGEENAN SOLUTION CONSUMPTION.

With changing lifestyle and dietary transition, there is an increase in intake of processed and packaged foods which tend to have a number of food additives. This has increased our consumption of these chemical substances. One of such additives is carrageenan (CGN) - E407. This paper reports the effect of 0.5 % carrageenan solution consumption on the main indices of endogenous intoxication in rats. Experimental studies were conducted on 48 non-linear, male, white rats weighing 180-200 g. The experimental animals had free access to 0.5% carrageenan solution (Sigma-Aldrich, USA) in drinking water. Control group of animals received pure water. Syndrome of endogenous intoxication was evaluated using measurement of the middle mass molecules contents in blood serum. We have found that even the minimal intake of carrageenan, triggers the mechanisms of endogenous intoxication in rats, starting in 2 weeks of consumption. 1 month consumption of carrageenan with drinking water in concentration of 0.5% is associated with significant increase in endogenous intoxication, manifested by increased contents of middle mass molecules (both the chain amino acids and the aromatic amino acids) in blood serum. From these facts, one may conclude that although carrageenan has been used widely in food as an emulsifier, a stabilizer, and a thickener for more than 50 years, some questions of its safety are still opened.

THE MECHANISMS OF APOPTOSIS INITIATION IN RATS WITH CHRONIC ENTEROCOLITIS COMBINED WITH STREPTOZOTOCIN-INDUCED DIABETES.

Diabetes mellitus is a multifactorial metabolic disease, characterized by hyperglycemia due to insulin deficiency or insulin resistance. A large number of experimental studies emphasizes the key role of apoptosis in the pathogenesis of diabetes. A deeper understanding of the apoptosis mechanisms, identifying of the predictors that positively or negatively influence on the cell death initiation, the correlation between some indices will improve therapeutic strategies for patients with diabetes and comorbidities, which makes the actuality of this study. The aim of the research was to study the mechanism of cell death initiation in rats with chronic enterocolitis combined with diabetes mellitus induced by streptozotocin. The experiments were performed on 48 white nonlinear mature male rats. The animals were divided into 4 groups: the 1st - control group (n=12), the 2nd - animals with diabetes mellitus (n=12), the 3rd - animals with chronic enterocolitis (n=12), the 4th - animals with diabetes mellitus and chronic enterocolitis (n=12). Apoptotic cells of blood leukocyte suspension and reactive oxygen species were identified by flow cytometry method. Correlation analysis was performed between all the studied indices. Coefficient of linear correlation (r) and its fidelity (p) was calculated that was accordingly denoted in the tables (correlation matrices). The correlation coefficient was significant at p<0.05. Development of chronic enterocolitis combined with streptozotocin-induced diabetes in rats is accompanied by an increase in the number of leukocytes with signs of apoptosis: the percentage of V+/PI- leukocytes is greater by 24.2%, as compared to the group with diabetes (p<0.01) and by 88.0%, compared to that with chronic enterocolitis (p<0.001); The value V+/PI+ of leukocytes exceeds the results of the chronic enterocolitis-group by 50.0%. Conducted correlative analysis showed that in case of chronic enterocolitis combined with streptozotocine-induced diabetes both free radical oxidation processes and the inflammatory process take part in the development of apoptotic death of leukocytes, but a stronger association is established with reactive oxygen species.

INVESTIGATION OF BONE MINERALIZATION IN PATIENTS WITH CORONARY HEART DISEASE COMPLICATED BY CHRONIC HEART FAILURE, STAGE II-A.

The majority of the studies have shown that individuals with cardiovascular diseases have a higher risk of experiencing bone loss and thus greater predisposition to risk of fracture. On the other hand there is growing evidence that individuals with low bone mass have higher mortality for cardiovascular events compared to patients with cardiovascular disease with normal bone mass. This research aims to investigate bone mineralization in patients with coronary heart disease complicated by stage II-A chronic heart failure. The study involved 33 men with coronary heart disease complicated by Stage II-A chronic heart failure. Bone mineral density was measured using dual energy x-ray densitometry of lumbar region of spine. Structural and functional changes of bone tissue of the lumbar spine have been found in 49,2% patients with coronary heart disease complicated by Stage II-A chronic heart failure, in particular, I stage of osteopenia - in 44,6%, II stage of osteopenia - in 27,7%, III stage of osteopenia - in 10,8% and osteoporosis - in 16,9%. It was established the same type of downward trend for BMD decreasing in L1 of patients with different stages of osteopenia, but in case of osteoporosis mineralization decreased equally in all vertebrae.

THE DETERMINATION OF CORRELATION LINKAGES BETWEEN LEVEL OF REACTIVE OXYGEN SPECIES, CONTENTS OF NEUTROPHILES AND BLOOD GAS COMPOSITION IN EXPERIMENTAL ACUTE LUNG INJURY.

Acute lung injury (ALI) remains a major cause of acute respiratory failure and death of patients. Despite the achievements at the current stage in treatment, morbidity and mortality of ALI remain high. However, a deeper understanding of the pathogenetic links of ALI, identifying of the predictors that positively or negatively influence on the course of the syndrome, the correlation between some pathogenetic mechanisms will improve therapeutic strategies for patients with ALI, which makes the actuality of this study. The aim of the research was to detect additional pathogenetic mechanisms of the acute lung injury development in rats based on a comparative analysis of the correlations between the level of reactive oxygen species in blood and bronchoalveolar lavage, contents of neutrophils and blood gas composition. The experiments were performed on 54 white nonlinear mature male rats 200-220g in weight. The animals were divided into 5 groups: the 1st - control group (n=6), the 2nd - animals affected by hydrochloric acid for 2 hours (n=12), the 3rd - animals affected by hydrochloric acid for 6 hours (n=12), the 4th - animals affected by hydrochloric acid for 12 hours (n=12), the 5th - animals affected by hydrochloric acid for 24 hours (n=12). Correlation analysis was performed between all the studied indices. Coefficient of linear correlation (r) and its fidelity (p) was calculated that was accordingly denoted in the tables (correlation matrices). The correlation coefficient was significant at p<0.05. Conducted correlative analysis showed that the level of ROS in neutrophils of blood in rats with modeled ALI had a high negative correlative linkage with pH of arterial blood in 2nd and 3rd experimental groups. Conducted correlative analysis of data in BAL showed that the level of ROS in neutrophils in rats with modeled ALI had a strong positive correlative relationship with the number of white blood cells in 3-rd, 4-th and 5-th experimental groups and positive correlative relationship with the absolute number of neutrophils in the same experimental group. Consequently, the main manifestation of acute lung injury is the development of hypoxia and respiratory acidosis that is caused by the violation of gases diffusion in the alveoli. On this background non-specific inflammatory reaction is developed at lung microvessels level with violation of lung homeostasis, which is iniciated by neutrophils' activation, which are producing ROS.

EXPERIMENTAL-MORPHOLOGICAL SUBSTANTIATION OF EXPEDIENCY TO USE THE SKIN GLUE "DERMABOND" FOR POSTOPERATIVE WOUND CLOSURE.

We aimed to investigate the morphological features of healing of postoperative wounds in the early stages of reparative process in the experiment, depending on the used type of the wound closure. It is proved that the nature and type of the scar depends on the processes that occur in the wound at the early postoperative stage, which in turn greatly affects the form of suture material used. The experiment included 20 male rats, weighing 180-200 g. All rats were anesthetized by a single intraperitoneal injection of sodium thiopental. After the shaving operative field, 2 cm full-thickness incision wound was made on the anterior surface of the abdomen in the longitudinal direction. As suture material for wound closure in the 1st experimental group (10 rats) we used surgical filament "Polyamide 4-0¼. In the 2nd experimental group (10 rats) wounds were closured by using skin glue "Dermabond". According from our experiment, the usage of skin glue creates better conditions for wound healing. Thus, to achieve a more aesthetic scar, we recommend applying skin glue instead of using nodal joints.