[A new paradigm for the treatment of sternomediastinitis]

OBJECTIVE

To analyze the results of simultaneous surgical treatment of sternomediastinitis compared to stage-by-stage approach.

MATERIAL AND METHODS

The study included 27 patients between October 2022 and March 2023. All patients underwent heart surgery through median sternotomy. There were 11 (40.7%) women and 16 (59.3%) men. Mean age of patients was 68.4±9.8 years. All patients were divided into 2 groups: 12 patients underwent partial necrectomy and vacuum wound therapy (or long-term dressings) before surgery (group 1), 15 patients underwent surgery without prior conservative treatment (group 2).

RESULTS

The most common causative agent of infection was staphylococcus (48.1%). In all patients, we found histological signs of osteomyelitis. Preoperative clinical status was similar in both groups. There were differences in the following indicators: C-reactive protein upon admission - 74.9±18.6 versus 94.8±23.8 mg/l, procalcitonin - 0.13 [0.02; 1.43] versus 0.21 [0.02; 0.94] ng/ml. Postoperative outcomes were similar in both groups. Mortality was 8.3% (n=1) and 13.3% (n=2), respectively.

CONCLUSION

Simultaneous combined surgical treatment (sequestrectomy + muscle flap grafting) demonstrates optimal results in the treatment of sternomediastinitis.

Toxicity of 13C-labeled linoleic and linolenic acids for diagnostic breath tests

Noninvasive stable isotope breath tests allow highly accurate and safe estimation of liver and biliary tract function. The aim of this study was to test 13С-labeled linoleic and linolenic acids intended for diagnostic use for acute and subchronic toxicity. The acids were synthesized using the patented method. A single intragastric administration of the tested compounds to experimental BALB/c mice and Wistar rats in the amounts exceeding clinical doses 500 to 2500-fold did not cause animal death. In the subchronic toxicity test, the rats received 5 to 25 times higher doses than recommended for clinical use in humans. In a 14-day follow-up period, no significant differences were observed between the main and the control groups in terms of weight, blood count (red blood cells, white blood cells, platelets), and blood biochemistry (hemoglobin, total protein, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, bilirubin). The studied compounds are safe at doses intended for oral administration and are recommended for further preclinical and clinical trials.

Synthesis of Au (III) polyacrylates and study of their tumoricidal activity

Aurumacryl is an incomplete metal salt of poly(acrylic acid) that exhibits hemostatic activity and inhibits the growth of transplantable carcinomas in vivo. The samples of aurumacryl synthesized following the original technique are insufficiently soluble, which complicates the study of the mechanisms involved in their synthesis and underlying their cytotoxic effect. The aim of this work was to study the impact of the following factors on aurumacryl properties: the molecular weight of the polyacrylate polymer in a range between 2 and 1,000 kDa, the presence of a counterion H+ or Na+, the molar ratio of AuCl– to the polyacrylate polymer (1 : 5 and 1 : 10), the total concentration of the polyacrylate polymer during synthesis (0.1 and 3%), and the type of drying (lyophilization). By comparing the cytotoxicity of aurumacryl samples with significantly different molar ratio of gold ions to the polyacrylate polymer against human breast carcinoma cells (MCF-7), we established that the proportion of the polymer and its molecular weight in the sample do not affect the biological properties of the synthesized substance. Using UV spectroscopy, we revealed that the concentration of Au (III) ions in aurumacryl determines its cytotoxicity.

Maintenance of the Cardiovascular Function in a Deeply Cooled Homeothermic Organism by Physiological Methods without External Rewarming

Gradual cooling of homeothermic organisms is followed by slowing and arrest of breathing and heart contractions. During deep cooling, even relatively slight artificial ventilation decreases the lower temperature limit of life (by 4.5-5°C) and provides minimum oxygen supply to the heart and whole body. This allows us to restore cardiovascular function and prevent animal death after lethal cooling without eternal warming.

[Physiological problems of alveolar circulation in the lungs]

Since the volume of the blood passing the lungs is great in the norm and especially during stressed muscle activity the question arises about the rate of the blood oxygenation. In the norm, when about 6 1 of the blood passes the lungs per minute, each 500 ml of the blood, which comprises the blood capacity of the lungs, is oxygenated during approximately 5 seconds. During muscle work, when the minute volume of the blood increases to 18-20 1, each 500 ml of the blood are oxygenated during 1-1.5 seconds. It is necessary to reveal the mechanisms of accelerating the blood oxygenation in the alveoli.

[Modern medical problems of microcirculation and hypoxic syndrome]

In this paper long known problems of microcirculation are shown, which were solved only during the last 40 years. They are concerned with the velocity and character of the capillary blood flow, the regulation of the capillary blood flow, the role of various vessels in the oxygen transport, the role of leukocytes in physiology and pathology of the capillary blood flow, with the special features of the function of lungs in supplying the whole organism with oxygen and with bioenergetic laws in the development of an organism adaptation to hypoxia. Here we considered a number of the most important medical problems of microcirculation and hypoxic syndrome. A relatively new factor in the capillary circulation is the fact that in the brain and heart capillaries there are sites with pO2 close to zero. They show that the capillary circulation has no central nervous regulation of the blood flow. The blood flow in these organs obeys only occasional oscillations. The new fact is that Krogh's rule about metabolism and oxygen exchange occurring only in the capillaries is abandoned. It is shown that almost 30% of consumed oxygen is delivered to the brain via arterioles, which changes our relation to the capillary circulation as a unique mechanism of the tissue supply with oxygen. The new fact is also the mass adhesion of leukocytes to the walls of microvessels, which results in the occlusion of the vessels followed by the development of the heart and brain ischemia. It was shown for the first time that contrary to previous ideas the alveoli in the lungs are supplied with blood from a powerful network of large microvessels from 20 to 50 microm in diameter rather than from thin arterioles. They make possible the passage of 6-121 of the blood in the norm and during stressed muscle activity--up to 18-231 of blood per minute. The principle is substantiated that during hypoxia only normal supply of an organism with oxygen may result in a complete adaptation of an organism to the deficit of oxygen.

[Restoration of respiratory function of an organism after cold oppressions without warming]

In experiments on rats studied influence of intravenous introduction NazdTA on respiratory function of rats after the full termination of breath at deep hypothermia. It is shown that such method without warming application it is possible to lower on 1.5-2.0 degrees C a temperature threshold of approach full a cold paralysis of respiratory function of an organism. It confirms the hypothesis put forward earlier about an important role of infringement of balance of ions of calcium in cytoplasm of cells in development of a pathology of an organism at deep hypothermia. The received results can be used at resuscitation of victims accidental hypothermia.

[Resuscitation of vital activity after cold arrest of respiration by physiological methods without rewarming the body]

BACKGROUND

The arrest of respiration during deep hypothermia means death, though at a low temperature the heart may rhythmically contract for 30-40 minutes more. The attempts of rewarming only shorten the time before the heart arrest. Calcium ions (Ca2+) are believed to accumulate in the nervous cells in cold. An excess of these ions inhibits the metabolism. Moreover it stimulates the cell proteases, which destroy the cell membranes.

AIM

The aim of the study was to make the the attempts to develop the methods of stimulating the respiration and heart without rewarming the body.

MATERIALS AND METHODS

The work was carried out on wite rats 250-320g in weight. We introduced disodium salt of ethylenediaminetetraacetic acid into the animals. The second method of blocking the mechanisms of the cold death was artificial respiration.

RESULTS

Ethylenediaminetetraacetic acid reacts with calcium ions, decreases their quantity in the blood, and, consequently, in a complex manner in the cell protoplasm. Artificial respiration not only increases the flow of oxygen into an organism but also decreases the lowest temperature threshold of the cold death of an organism.

CONCLUSION

A decrease in the surviving threshold by 1.5-1.8 degrees C is very important from the point of view of reanimation of an organism since to preserve life in the critical period of reanimation each 0.5 degrees C are important. Prolongation of minimal frequency of heart contractions and maintaining a minimal arterial blood pressure in an overcooled organism given the body temperature of 11-12.5 degrees C is a special problem of great interest associated with many physiological and biological parameters.

[Diagnostic capabilities of single-photon emission computed tomography/computed tomography in the evaluation of perfusion disorders in pulmonary hypertension]

OBJECTIVE

to study the diagnostic capabilities of single-photon emission computed tomography/computed tomography (SPECT/ CT) in the evaluation of lung perfusion in pulmonary hypertension (PH).

SUBJECT AND METHODS

Ten patients with pulmonary hypertension were examined. Its diagnosis was verified in accordance with the Russian guidelines for the diagnosis and treatment of PH, by conducting a set of studies involving right heart catheterization. CT angiopulmonography was carried out in all the patients. At the same time all the patients underwent a radiological study on a combined SPECT/CT scanner with the intravenous injection of the radiotracer 9mTc-MAA (technetium-99m-labelled macroaggregated albumin) with an activity of 2-4 mCi.

RESULTS

CT-angiopulmonography revealed no thrombi in the pulmonary artery lumen in 7 patients and confirmed the diagnosis of pulmonary thromboembolism (PTE) at the level of segmental vessels in 3. SPECT/CT examination identified 5 cases of non-thromboembolic PH and 5 cases of PTE with consideration for SPECT perfusion defects and no visible lung tissue (fibrous or other) changes on a CT scan. It should be noted that the 5 patients diagnosed as having PTE included 2 patients in whom PTE had not previously been diagnosed at CT angiopulmonography. This may be due to that this technique cannot always clearly visualize thrombi in the pulmonary vessel lumen at a subsegmental level.

CONCLUSION

The inivestigations have indicated that, by clearly ivisualizing pulmonary aanatomy, morphology, and function, combined SPECT/CT imaging is a valuable diagnostic tool in detecting lung pathology.

Blood circulation in rat lungs under conditions of reduced oxygen level in inhaled air

According to some authors, reduction in oxygen level in the lung alveoli results in constriction of afferent vessels, while others observed no vessel constriction. The issue is of principle importance in relation to the lung involvement in body adaptation to hypoxia. Conventional methods are inefficient to solve it, therefore we used a contact microscope allowing observation of lung circulatory system structure and condition of the lung circulatory system in whole, virtually intact animal, on whole undamaged lungs in situ, at normal physiological lung position in the thorax. We found that large vessels carrying blood to the alveoli do not constrict or dilate at reduced Po(2)in lung alveoli. These vessels with a diameter of 15 to 40 μ and more are the only blood source for alveoli.

[Modern medical problems of energy exchange in humans]

In a living organism 72% of energy exchange occur in the visceral organs, which comprise only 5-6% of the total body mass. The remaining energy is spent at the expense of the skin, bones, connective tissues, resting muscles. The level ofenergy expenditure determines the general physiological state of a human organism, serves for the diagnostics of various diseases, in particular, the diseases of endocrine system, the disruptions of thermoregulation, protein, carbohydrate, and lipometabolism, etc. It should be mentioned that in modern textbooks of physiology, pathophysiology, and biology the problem of energy exchange in humans and animals is given inadequate consideration. Traditionally it occupies only 2-2.5% of the content. Meanwhile, new problems of energy exchange have appeared recently, which almost never were advanced earlier. These are,for example, the reasons and mechanisms of high energy expenditure under conditions of metabolism, the significance of the coefficient of efficiency of a human organism in physiology, special processes previously unknown of the organism heat exchange with the environment, physiological and social components of human energy exchange. There is also a problem of a theoretical possibility of life without energy.

[Critical review of preconditioning]

Adaptation of the brain and myocardium to ischemia by short shutdowns of the regional circulation (preconditioning) is an interesting and important subject. Nowadays it is discussed with animation in the scientific literature. However this problem is very complicated and contains a lot of contradictions. We tried to examine these contradictions and tofind the reasons for this phenomenon.

[Function of alveoles as a result of evolutionary development of respiratory system in mammals]

Reaction of hemoglobin oxygenation is known to occur for 40 femtoseconds (40 x 10(-15) s). However, the process of oxygen diffusion to hemoglobin under physiologic conditions decelerated this reaction approximately billion times. In mammalian lungs, blood is moving at a high rate and in a relatively high amount. The human lung mass is as low as 600 g, but the complete cardiac output approaches 6 1/min. In rat, from 20 to 40 ml of blood is passed for q min through the lung whose mass is about 1.5 g. Such blood flow rate is possible, as in lungs of high animals there exists a dense network of relatively large microvessels with diameter from 20 to 40 microm and more. In spite of a large volume and a high blood flow rate hampering oxygen diffusion, the complete blood oxygenation occurs in lung alveoli. This is due to peculiar mechanisms that facilitate markedly the oxygen diffusion and that developed in alveoli of mammals in the course of many million years of evolution of their respiratory system. Thus, alveolus is not a bubble with air, but a complex tool of fight with inertness of diffusion. It is interesting that in lungs of the low vertebrates, neither such system of blood vessels nor alveoli exist, and their blood flow rate is much lower than in mammals.

[Brain hypoxia and the role of active forms of oxygen and of energy deficit in the neuron degeneration]

The concepts about physiological mechanisms of oxygen transport to the brain have recently changed substantially. Precise data on the capillary blood flow rate, on a substantial dispersion of corresponding values, on the influence of the capillary blood flow rate on pO2 in the capillaries and tissues have evolved. Krog's paradigm about an exclusive role of capillaries in the gas exchange between the blood and tissues amounting to almost 100 years was abandoned. All these data also changed the concepts about the development of various types of hypoxia in the brain tissues. The study of pO2 in the brain at normoxia showed that pO2 exhibits the fluctuations from 1-2 to 80-85 mm Hg. This means, in particular, that hypoxic phenomena take place in the normal healthy brain. During hypoxia the mass adhesion of leukocytes to the walls of microvessels was shown to hamper the capillary blood flow and can become one of the reasons for the death of the brain during hypoxia. The brain hypoxia is not an occasional pathologic process. It exists in an intact brain owing to physiological fluctuations of pO2 in various microregions of the brain. It occurs during various physiological states in the norm and also during various illnesses associated with the changes and disruptions in the oxygen transport. The final stage of hypoxia is the destruction of the cells. The development of this process and its particular reasons are nowadays the subject of multiple physiological and biochemical studies. Certain changes are introduced into modern ideas about the reasons for the degradation of the nervous cells upon hypoxia. The degradation of the neurons during hypoxia or anemia is postulated to be associated not only with the cell generation of active forms of oxygen (AFO), but also with the energy deficiency. This means a deficient synthesis or a complete absence of ATP in a cell during hypoxia, anemia, and ishemia.

[Cold pathology and experimental therapy of deep hypothermia]

A complete cold paralysis of respiration and thermoregulation occurs in rats at the temperature in the brain 16.6 +/- 0.3 and in the rectum 15.2 +/- 0.3 degrees C. Under the conditions of room temperature 18-19 degrees C, the respiration never restores, and the animals die. This is believed [6] to be the result of calcium ion Ca2+ accumulation in the cells of respiration and thermoregulation centers. After the arrest of respiration the animals were injected with the solution of disodium salt of ethylenediaminetetraacetic acid (Na2EDTA), which binds calcium ions in the blood and facilitates their removal from the cell (explanations in the text). In 7-9 min after the injection the calcium content in the blood decreased and the respiration began to restore at the temperature of the cold paralysis. Thermoregulation was also restored. All the test animals survived. All the control animals, which were not injected with Na2EDTA, died.

Direct renin inhibitor aliskiren in women with menopausal metabolic syndrome and arterial hypertension

Aim. To study the effectiveness of a direct renin inhibitor, aliskiren, in patients with menopausal metabolic syndrome (MMS), and to assess aliskiren effects on blood pressure (BP), carbohydrate and lipid metabolism parameters, microalbuminuria, and arterial stiffness. Material and methods. The study included 23 women with MMS, to whom aliskiren monotherapy (150-300 mg/d) was administered. At baseline and in the end of the study, anthropometry, carbohydrate and lipid metabolism parameters assessment, 24-hour BP monitoring, and arterial stiffness assessment by volume sphygmography were performed. Results. By the end of the study, most parameters of circadian BP profile significantly decreased. Target levels of systolic and diastolic BP were achieved in 80 % of the patients. There was a significant reduction in postprandial glucose levels. According to the volume sphygmography results, a decrease in arterial stiffness was accompanied by a significant reduction in pulse wave velocity and augmentation index, with normalization of the former parameter. Conclusion. Aliskiren therapy demonstrated not only high antihypertensive effectiveness in MMS patients, but also a reduction in postprandial glucose levels and arterial stiffness.

Perspectives of impaired glucose tolerance management in patients with metabolic syndrome

Aim. To assess the effectiveness of vildagliptin, its effects on visceral obesity (VO), carbohydrate and lipid metabolism parameters, and circadian profile (CP) of blood pressure (BP) in patients with metabolic syndrome (MS), Stage I arterial hypertension (AH), and impaired glucose tolerance (IGT). Material and methods. The study included 30 patients, aged 18-60 years (16 men and 14 women). All patients had IGT, VO, and Stage I AH. Previously prescribed antihypertensive therapy (AHT) was not modified after the start of the study. In all participants, carbohydrate and lipid metabolism parameters, BP CP, and body weight were measured at baseline and after 24 weeks of vildagliptin treatment. Results. Vildagliptin therapy was associated with a significant reduction in body weight, waist circumference, postprandial and fasting glucose levels, the levels of total cholesterol and low-density lipoprotein cholesterol, as well as with a sustained reduction in systolic and diastolic BP levels. Conclusion. Vildagliptin therapy resulted in weight reduction, improved carbohydrate and lipid profiles, and target BP achievement, without inducing hypoglycemia episodes.

Imidazoline receptor agonist moxonidine and arterial hypertension treatment in women with menopausal metabolic syndrome

Aim. To assess the long-term effectiveness and safety of moxonidine (Physiotens®), as antihypertensive treatment in patients with metabolic syndrome (MS), including women with menopausal MS. Material and methods. The study included 274 patients: 203 women (74 %) and 70 men (26 %). Postmenopausal women comprised a separate study subgroup. At baseline and after 24 weeks of moxonidine treatment, all participants underwent anthropometry and the measurement of systolic and diastolic blood pressure (SBP, DBP), lipid and carbohydrate metabolism parameters. Results. Moxonidine therapy was associated with a reduction in SBP and DBP levels. A positive dynamics in the levels of fasting glucose, total cholesterol, low and high-density lipoproteins (LDL, HDL), and triglycerides was observed. The changes in these parameters were similar among postmenopausal women and all study participants. Conclusion. In MS patients, moxonidine improved circadian BP profile, and also demonstrated beneficial effects on carbohydrate and lipid metabolism parameters in women with menopausal MS.

[Morphodynamic analysis of lung microcirculation (a supravital morphological study)]

Using the system of contact optics, the circulation (microcirculation) was studied in the lungs of 15 adult Wistar rats during the normal physiological location of the organs inside the thorax. A 4x4 mm "window" was made in the tissues of the thorax of an anaesthetized rat, through which the pleura was incised, resulting in the lung collapse. The lung was filled with oxygen or hypoxic gas mixture under the pressure of 10-15 cm of water column through a tracheotomic cannula. Then the lung was brought in contact with the contact objective aperture (1.7 mm in diameter). Each alveolus was supposed earlier to be supplied with blood via a thinnest (5-10 microm in diameter) lung arteriole. The present study has shown that there exists a system of wide (20-30 microm in diameter and larger) microvessels, which run between the alveoli. These microvessels surround each alveolus, practically, from all the sides. In such a manner each alveolus is supplied by a maximal amount of blood. Such a structure of the lung circulation system accounts for a great blood flow through the lungs (up to 6 1 per minute in humans) and a rapid saturation of the blood with oxygen.

[Development of energetics in evolution of the living world. Stage, digits, postulates]

This work deals with the current stage of study of energy exchange between living organisms and the environment. In the epoch of molecular biology, study of energy exchange might have seemed a study of old, well known concepts. However, the retrospective insight into the energy exchange of quite a few organisms allows obtaining new data about development of energetics of the living world, approaches to interesting comparisons, opens the earlier unknown quantitative relations in energetics of living organisms, provides a possibility of analyzing causes of very high values of energy consumption by living organisms, causes of different sensitivity of living organisms to deficit of energy, etc. Based on all these data, there have been noted 12 principal moments or postulates in development of energetics of the living world from the most ancient to the present time.

[Disturbance and restoration of the cortical brain microcirculation in the global ischemia]

In the global brain ischemia, the leucocytes are adhered in the venules and smallest veins thus impeding the capillary blood circulation. In a more severe ischemia, the leucocytes conglomerates are formed. This causes the occlusion of venous vessels, blocks the venous outflow and practically is a reason of animal' death from ischemia. We suggest a method for removing leucocytes and leucocytes conglomerates from vessels.

[Modern problems of energetics of internal organs]

The review considers the general mechanisms of energy exchange in an organism, which determine its volume. The data are given on the energy exchange in various internal organs (heart, lungs, kidneys, liver, gastrointestinal tract). The reasons for a high energy exchange in the internal organs are considered and also for their substantial role in participating in the total energy budget of an organism.

[Leucocytosis and leucocyte adhesion in brain ischemia development]

Our previos studies revealed the phenomenon of leucocyte adhesion to microvessel walls in gradually developing brain ischemia. The problem of effect of the blood leucocyte number in the brain ischemia upon number of the adhesion acts was considered. This work attempts to solve this problem. Number of leucocytes was measured in the white rat blood after bilateral ligation of the carotid arteries and gradual increment of the brain ischemia. Simultaneously a number of leucocytes that adhered to the brain venule wall internal surface was recorded. Beginning of the ischemia was shown to quickly increase the number of leucocytes in the blood. In 2 hours, the number increased over two-fold. At this moment, the number of adhered leucocytes practically did not increase. In 3 hours, the number of the blood leucocytes started decreasing, whereas the number of the adhered leucocytes started increasing. By the 5th hour after artery ligation, the number of the blood leucocytes decreased to initial value, whereas the number of adhered leucocytes increased over 2.5-fold. The leucocytes adhesion seems to be unrelated to increase of their number in the blood. Reduction of the leucocyte amount in the blood on the 5th hour of the ischemia is associated with increase of the leucocyte adhesion acts in the brain. Reduction of the blood leucocyte number in grave ischemia of the brain might be a sign of increase of the leucocyte adhesion act number which leads to worsening of microcirculation and perishing of the organism.

Mechanism of suppression of physiological functions in hypothermia and means for their stimulation without body warming

Cold-suppressed thermoregulatory reactions and respiration in rats in deep hypothermia (rectal body temperature (25-22 degrees C) were shown to be stimulated by injecting disodium ethylenediaminetetraacetic acid (EDTA) solution into the blood stream of cold rats at a dose of 16.5 mg/100 g (0.0045 mmol/100 g). EDTA binds Ca2+ ions in the blood, forming complexes. Increases in cold shivering and pulmonary respiration (by 5 min after the start of administration) coincided with a reduction in the blood Ca2+ concentration by 42-45% of normal. By 15 min after the start of the EDTA injection, the blood Ca2+ concentration returned to the normal level present in cold rats before EDTA treatment. This was accompanied by suppression of cold shivering and pulmonary respiration. Repeated injection of EDTA into the blood stream produced a new drop in blood Ca2+ and repeated stimulation of cold shivering and pulmonary respiration.

[Life under minimal energy expenses]

Vital activity is impossible without energy. Lung ventilation, heart activity, digestion, secretion, locomotion--these functions require and consume a substantial amount of energy. But preservation of viability requires comparatively small amount of energy, and in some cases can manage almost without energy. A prolonged preservation of viability with minimal energy consumption we conventionally call life without energy. This special feature of living organisms is considered in the present work in a comparative physiological aspect.

Recovery of brain microcirculation during ischemia

Blood pressure in the circle of Willis in rats decreased to about 40 mmHg after ligation of both carotid arteries. Developing ischemia was accompanied by massive adhesion of leukocytes to the walls of brain venules and the smallest veins. Blood pressure in the vessels of the circle of Willis decreased to 16-20 mmHg 2 h after ligation. The number of adhesion events increased sharply. Leukocyte aggregates formed in these vessels, resulting in complete occlusion of the vessels and death of the animals. These processes were found to be reversible. Introduction of 4-4.5 ml of the plasma replacement polyglucin directly into the vessels of the circle of Willis "washed away" the leukocyte aggregates and some of the adhered leukocytes, with restoration of circulation in venules and the smallest veins by 10-15 min.

[Physiological blocking of the mechanisms of the cold death]

Physiological mechanisms of the cold paralyses of the main, most important functions during deep hypothermia of a homeothermic organism were studied. The reasons for the organism death upon deep cooling were revealed. The cold paralyses and the following organism death were shown to be accounted for to a great extent by the specific impairments in the ion exchange between the nervous cells of vegetative brain centers and the intercellular medium and the blood. Removing these impairments with the help of the methods developed in the authors laboratory allows the lost physiological functions of an organism to be restored for a time without rewarming the body.

[Mechanisms of suppression of physiological function in hypothermia and a way of their restoration without body warming]

It was shown that in hypothermic rats (rectal temperature 25-22 degrees C) it was possible to stimulate responses that had been suppressed by cold (i. e. thermoregulation and breathing) with the aid of injecting a solution of ethylenediaminetetraacetic acid disodium salt (EDTA) in quantity 16.5 mg/100 g of body weight (0.0045 mmol/100 g) into the blood stream of the cooled animals. EDTA connects calcium ions in blood and forms complexes. It was shown that enhancement of cold shivering intensity and that of breathing (in 5 min after beginning the injection of EDTA) coincided with a 42-45 % reduction of [Ca2+] in the blood]. After 15 min following the beginning of injection of EDTA [Ca2+] into the blood stream, a return to the initial level was observed in cooled animals. Simultaneously we observed suppression of the cold shivering and breathing. The repeated injection of EDTA again caused similar fall of [Ca2+] in the blood and the following enhancement of cold shivering and breathing.

Leukocytes as a cause of microcirculatory dysfunction

Massive leukocyte adhesion to the endothelium of pial veins in rats with ischemic injury of brain tissue was studied by the method of vital microscopy.

[Mechanisms of disrupting the microcirculation in the brain during deep hypothermia development]

The number of the acts of leukocyte adhesion per unit of the vessel length was shown to increase gradually in the venous brain vessels during gradual cooling of the white rat from the body temperature in the rectum of approximately 37 to 13.5 +/- 0.2 degrees C. Upon a very deep hypothermia at the level of body temperature of 15 degrees C, the adhesion ofleukocytes to the walls of the brain microvessels gains a mass character. As the body temperature decreases to 13.5 +/- 0.2 degrees C, the respiration gets arrested. This coincides with an aspecially abrupt increase in the number of the acts of adhesion and with stretching the venules and smallest veins. The dynamics of these phenomena resembles the development of the mass adhesion of leukocytes during various kinds of hypoxia. There are reasons to believe that the adhesion of leukosytes during hypothermia disrupts the microcirculation and provokes the development of hypoxia in the cooled brain.

[Modern theoretical and practical problems of homoiothermia and thermoregulation]

The adjuncts to the existing determinations of homoiothermia are made on the basis of new data, the principles of temperature adaptation of humans and homoiothermal animals are presented. The main purposes of the thermoregulation system of homoiothermal animals and humans in various temperature excesses are formulated. The arguments are advanced in favor of the fact that in the thermoneutral zone the thermoregulation system goes from the principles of regulating the temperature homeostasis by one or several temperature points of a body to the regulation by the fluctuations of the total heat content of an organism, which increases the sensitivity and the accuracy of the thermoregulation system operation. The physiological mechanisms are described of determining (measuring) the total heat content of a body.

[Restoration of microcirculation in the brain during ischemia]

The work shows that, after slinging two carotids in rats, the blood pressure in the circle of Willis decreases to approximately 40 mm Hg. The developing ischemia is accompanied by a mass adhesion of leukocytes to the walls of the brain venules and smallest veins. In two hours after slinging, the blood pressure in the vessels of the circle of Willis decreases to 16-20 mm Hg. The rate of adhesion increases abruptly. In these vessels the leukocyte conglomerates are formed which results in complete occlusion of the vessels and the death of animals. These processes are shown to be reversible. The insertion of 4.0-4.5 ml of plasmosubstituent polyglucin into the vessels of the circle of Willis "washes away" the leukocyte conglomerates as well as a part of adhered leukocytes and restores the blood flow in the venules and smallest veins for 10-15 min.

[About a correlation between calcium ion concentration (Ca2+) in the blood and the state of physiological functions in animals in deep cooling]

The changes in physiological functions of the organism (respiration, functions of the heart and vessels, thermoregulation) were studied. The concentration of Ca2+ ions in the blood of white rats was determined by the ion-selective electrodes at various stages of hypothermia. The aim of the study was to reveal changes in the blood concentration of ionized calcium in animals during their gradual cooling. In deep hypothermia (16 degrees C), calcium ion concentration in the blood increased by 30% against the norm which coincides with arrest of the cold shivering and lung ventilation. An increased content of Ca2+ in the blood is supposed to result in an increase in the content of these ions in the intercellular liquid and in the nervous cells, which is one of the reasons for the cold paralysis of the respiration and thermoregulation centers.

[Stimulation of physiological functions in cooled rats without rewarming after introducing ethylenediaminetetraacetate into lateral ventricles of the brain]

On cooling the animals to the rectum temperature from approximately 37 to 24-28 degrees C the decreases were shown to occur in the frequency and amplitude of respiration motions, in the intensity of muscle electrical activity (thermoregulation muscle tone and cold muscle shivering), in the frequency of heart contractions. In 3-8 min after introducing ethylenediaminetetraacetate into a lateral ventricle of the rat brain the frequency and the amplitude of respiration motions increased statistically reliable and so did the intensity of thermoregulation muscle tone and cold muscle shivering (judging from the total muscle electrical activity). The doses of EDTA, which caused this effect, were by a factor of 30 - 100 less than the doses, which caused a similar stimulation of the functions in cooled animals after introduction into the blood.

[Physiological problems of biological evolution. "Errors" in the development of physiological functions]

During the evolution the physiological functions grow more perfect and complex. However, sometimes a developing function can show some evidence of regress and in certain cases can become the cause of dangerous diseases. The autoimmune diseases are among them. We conventionally call such cases the "error" of the evolution. In this work a negative role of leukocytes in the brain microcirculation is considered. With the help of experimental studies it was shown that leukocytes owing to their large volume (by a factor of 2-2.5 greater than the volume of an erythrocyte) slow down the capillary blood flow. As the result of the increasing tendency to adhesion, under the influence of hypoxia they make leukocyte conglomerates which cause the occlusion of venules and smallest veins of the brain. This is the reason for the known effect "no reflow" and results in an organism death.

[Leukocyte adhesion to walls of the rat pial venules in normoxia and during brain ischemia]

With the help of contact optic system direct observations were carried out on leukocyte movements and on the acts of their adhesion to the inner surface of the walls of pial venules of the rats in normoxia and ischemia resulting from ligating two carotid arteries. After ligating the carotid artery and subsequent gradual development of ischemia, an abrupt increase in the number of the acts of adhesion to the walls of pial venules was shown to occur, the leukocytes adhere to each other inside the venules. A complete occlusion of venules and small veins results, which can be one of the reasons for the animal death in brain ischemia.

[The role of leukocytes in microcirculation dynamics in the norm and pathology]

The physiological functions grow to be more perfect and complicated in the process of evolution. However, a developing function could display some evidence of regress and, in certain cases, it can trigger serious diseases including autoimmune ones. Conventionally, we refer to the above cases as to "errors" of evolution. The present case study deals with a negative factor of leukocytes in the cerebral microcirculation. Leukocytes were shown, experimentally, to inhibit the capillary blood flow owing to their big volume (2-2.5-fold more versus that of erythrocytes). An increasing trend to adhesion due to hypoxia is responsible for shaping of leukocytes' conglomerates, which cause the occlusion of venules and of the smallest cerebral veins. It entails the effect known as "no re-flow" resulting in death.

[Thermoregulation in the comfort temperature zone]

Under constant adequate temperature conditions (comfortable for a man) the retention of temperature homeostasis was shown to require a continuous functioning of the physiological thermoregulation system to prevent short-term and whole day deviations of the temperature from the physiological level. Under adequate temperature conditions the thermoregulation system was shown to attain its highest sensitivity and accuracy. It is possible that this occurs owing to physiological control over the total body heat content being included into the process of thermoregulation. The data are given on the existence and "structure" of the physiological mechanisms of such a control.

[Morphodynamic analysis of the role of leukocytes in the microcirculation disorder of the cerebral cortex]

The aim of this work was to establish the reasons for the disturbances of microcirculation (no reflow) during various kinds of oxygen starvation of the brain. Using contact optics and video-recording, direct observations were performed and leukocyte and erythrocyte displacement was monitored in the blood vessels of rat cerebral cortex in vivo in normoxia, during the development of various kinds of oxygen deficiency up to the terminal periods of life of an organism. In normoxia leukocytes were shown to decelerate erythrocyte movement in capillaries and to cause the irregularity of the capillary blood flow. Using the color videofilm recording it was shown that at deep stages of brain oxygen deficiency the disturbances of microcirculation up to its complete cessation were explained by the occlusion of venous microvessels as a result of massive adhesion of leukocytes to the inner surface of venules and the smallest veins. The co-adhesion of leukocytes was also found to take place. The latter leads to the formation of large leukocyte aggregates in venous vessels, results in "no reflow" effect. Leukocyte aggregates in veins block the venous outflow from the brain and may become the immediate cause of organism death as a result of disruption of circulation and oxygen deficiency.

[Bioethical problems in contemporary physiology]

The review is devoted to problems of bioethics in modern physiology. Definition of bioethics is presented. One can find short history of the problem. Existing discripancies between interests of scientific research and modern rules of bioethics are discussed. Main principles of experiment in physiology organisation and role in its organisation of bioethics rules are formulated.

[Current views on oxygen transport from blood to tissues]

During the recent 25-30 years, sophisticated experiments and mathematical simulation significantly changed the generally accepted theory of oxygen transport in tissue, which was based on two major postulates, namely: 1) Blood flows in capillaries continuously at uniform velocity, 2) Gas circulation between blood and tissue takes place exclusively in capillaries. As was shown by modern research techniques, blood flow in microvessels has irregular sharp velocity fluctuations in very short time intervals (seconds). In addition, mean velocity of blood flow in microvessels of the same caliber and the same micro-region of tissue may differ several times. Therefore, efficiency of microcirculation reactions may be assessed exclusively witH mean blood velocity in capillaries of the whole micro-region, and with complicated changes of the histogram of mean velocity distribution in capillaries. It was shown that arteriolas and venulas of inactive muscles and brain account for 30 to 50% of gas circulation between blood and tissue. This resulted in fundamental change of the previous postulates in the area of tissue gas circulation physiology, and, in effect, in replacement of oxygen transport paradigm created by A. Krog. This study is an attempt to present a new modern concept of oxygen transport in tissue, to show its research significance, and possible applications.