Decompression Chamber Research Articles

Acute Hypobaric Hypoxia Causes Alterations in Acetylcholine-Mediated Signaling Through Varying Expression of Muscarinic Receptors in the Prefrontal Cortex and Cerebellum of Rats' Brain.

Sharma, Narendra Kumar, Mansi Srivastava, Tikam Chand Dakal, Vipin Ranga, and Pawan Kumar Maurya. Acute hypobaric hypoxia (HH) causes alterations in acetylcholine-mediated signaling through varying expression of muscarinic receptors in the PFC and cerebellum of rats' brain. High Alt Med Biol. 00:00-00, 2024. Background: Muscarinic receptor (CHRM) proteins are G-protein-associated acetylcholine receptors found in neuronal membranes. Five major subtypes, CHRM1-CHRM5, modulate acetylcholine in central nervous system signaling cascades. CHRM1, CHRM3, and CHRM5 are linked to Gαq/Gα11 proteins, whereas CHRM2 and CHRM4 are linked to Gαi/Gαo proteins. Objective: Limited research has been conducted to explore the impact of HH on CHRM gene expressions. It is caused by low oxygen availability at high altitudes, which impairs neurotransmission, cognitive performance, and physiological functions. Previous studies have shown that exposure to hypoxia leads to a reduction in CHRM receptors, which in turn causes alteration in signal transduction, physiological responses, cognitive deficits, and mood alterations. Method: In the present study, we have used semiquantitative PCR to measure muscarinic receptor gene expression after 6, 12, and 24 hours of HH exposure at 25,000 feet using a decompression chamber in rat brain's PFC and cerebellum. Result: We have found that CHRM1-CHRM5 downregulated after acute exposure to hypoxia until 12 hours, and then, the expression level of these receptors increased to 24 hours when compared with 12 hours in PFC. All subtypes have shown a similar pattern in PFC regions under hypoxia exposure. On the other hand, these receptors have shown altered expression at different time points in the cerebellum. CHRM1 and CHRM4 acutely downregulated, CHRM2 and CHRM5 downregulated, while CHRM3 upregulated after hypoxia exposure. Conclusion: Our study, for the first time, has shown the altered expressions of muscarinic receptors under temporal hypoxia exposure. The altered expression pattern has shown an association with acclimatization and protection against necrosis due to hypoxia. This study may pave further investigations for understanding and addressing the cognitive, behavioral, and physiological impacts of hypoxia and therapeutic development.

Thymus morphological characteristics in acute and chronic colitis in animals with different hypoxia tolerance

Hypoxia is connected with inflammation, and the severity of inflammatory diseases predominantly depends on individual tolerance to oxygen deficiency. Hypoxia-inducible factor, HIF-1, regulates the thymus functional state, and its activity varies in organisms with different hypoxia tolerance. It is likely that differences in individual hypoxia tolerance and the associated HIF-1 functional activity may influence the inflammatory diseases severity, such as acute and chronic ulcerative colitis. The study aim is to characterize the thymus morphological changes during acute and chronic colitis in animals with different hypoxia tolerance. The hypoxia tolerance of male C57Bl/6 mice was determined by “gasping time” at an “altitude” of 10,000 m in a decompression chamber. A month after determining hypoxia tolerance, the animals were modeled as acute colitis by replacing drinking water with a 1.5% dextran sulfate sodium for 5 days; the animals were removed from the experiment on the 7th day. Chronic colitis was modeled by animals consuming a 1% dextran sulfate sodium on days 1-4, 12-14 and 22-26; animals were removed from the experiment on the 60th day. The volume fraction of thymus structural and functional zones was assessed using the point counting method. The relative number of different thymic bodies types was assessed: consisting of 3-5 cells, 5 or more epithelial cells, with keratohyalin deposits and thymic bodies in the form of cyst-like cavities. During acute colitis, in the thymus only in susceptible mice, there was a significant cortex narrowing and an increase in the number of thymic bodies consisting of 5 or more cells. In chronic colitis, only in susceptible animals in comparison with the control group, the cortex volume fraction and the cortex to the medulla ratio increased significantly. In susceptible mice, the number of bodies with keratohyalin increased. In tolerant animals, the indicators did not change. Thus, differences in the thymus response to acute and chronic ulcerative colitis were identified between tolerant and susceptible to hypoxia animals. Only in susceptible mice, in acute colitis, was observed cortex narrowing, but in chronic colitis, cortex hyperplasia. The data obtained must be taken into account when conducting experimental studies of the thymus.

Spontaneous and Stimulated Production of Cytokines by Blood Cells Ex Vivo as a Biomarker of Initially High or Low Hypoxia Resistance in Rats.

Spontaneous and stimulated production of cytokines by peripheral blood cells obtained from the caudal vein of male Wistar rats was assessed before testing their resistance to oxygen deficiency in a decompression chamber. To study the spontaneous production of cytokines, heparinized blood cells were incubated in a culture medium (24 h, 5% CO2, 37°C) and the content of proinflammatory cytokines IL-6 and TNFα and anti-inflammatory IL-10 in the culture medium was assessed by ELISA. To stimulate cytokine production, blood cells were incubated for 24 h with LPS, phytohemagglutinin, and concanavalin A at final concentrations of 2, 4, and 4 μg, respectively. Two weeks after blood sampling, individual resistance of the animals to hypoxia in a decompression chamber was determined. In animals with low resistance to hypoxia, the levels of spontaneous production of all three cytokines were significantly higher, while after stimulation, the level of IL-1β increased by more than 2 times. The animals with spontaneous production of IL-10>50 pg/ml, IL-6>10 pg/ml, and TNFα>10 pg/ml, as well as with the increase in IL-1β production by more than 2 times upon stimulation were classified as low-resistant. At IL-10<15 pg/ml, IL-6<9 pg/ml, and TNFα<7 pg/ml, as well as the absence of the increase in IL-1β production upon stimulation, they were classified as high-resistant. The identified features of spontaneous and stimulated production of cytokines can be used as non-invasive biomarkers to determine the resistance to hypoxia without exposure to sublethal hypoxia in a decompression chamber.

Changes in the Expression of Genes Regulating the Response to Hypoxia, Inflammation, Cell Cycle, Apoptosis, and Epithelial Barrier Functioning during Colitis-Associated Colorectal Cancer Depend on Individual Hypoxia Tolerance.

One of the factors contributing to colorectal cancer (CRC) development is inflammation, which is mostly hypoxia-associated. This study aimed to characterize the morphological and molecular biological features of colon tumors in mice that were tolerant and susceptible to hypoxia based on colitis-associated CRC (CAC). Hypoxia tolerance was assessed through a gasping time evaluation in a decompression chamber. One month later, the animals were experimentally modeled for colitis-associated CRC by intraperitoneal azoxymethane administration and three dextran sulfate sodium consumption cycles. The incidence of tumor development in the distal colon in the susceptible to hypoxia mice was two times higher and all tumors (100%) were represented by adenocarcinomas, while in the tolerant mice, only 14% were adenocarcinomas and 86% were glandular intraepithelial neoplasia. The tumor area assessed on serially stepped sections was statistically significantly higher in the susceptible animals. The number of macrophages, CD3-CD19+, CD3+CD4+, and NK cells in tumors did not differ between animals; however, the number of CD3+CD8+ and vimentin+ cells was higher in the susceptible mice. Changes in the expression of genes regulating the response to hypoxia, inflammation, cell cycle, apoptosis, and epithelial barrier functioning in tumors and the peritumoral area depended on the initial mouse's hypoxia tolerance, which should be taken into account for new CAC diagnostics and treatment approaches development.

Evaluation of colour vision impairment during acute hypobaric hypoxia in aviation medicine: a randomized controlled trial

The digitization of aircraft cockpits places high demands on the colour vision of pilots. The present study investigates colour vision changes upon acute exposure to hypobaric hypoxia. The digital Waggoner Computerized Color Vision Test and the Waggoner D-15 were performed by 54 healthy volunteers in a decompression chamber. Respective altitude levels were sea level, 10,000 or 15,000 ft for exposure periods of 15 and 60 min, respectively. As for 60 min of exposure a significant decrease in colour perception was found between subjects at 15,000 ft as compared to the control group as well as between subjects at 15,000 ft as compared to subjects at 10,000 ft. No significant difference was found in the comparison within the 15,000 ft groups across time points pre-, peri-, and post-exposure. Thus, pilots appear to experience only minor colour vision impairment up to an exposure altitude of 15,000 ft over 60 min of exposure.

Histological and cytochemical analysis of the brain under conditions of hypobaric hypoxia-induced oxygen deficiency in albino rats

High altitude sickness is a life-threatening disease that occurs among acclimatized individuals working or living at a high altitude accompanied by hypobaric hypoxia exposure. The prolonged influence of hypobaric hypoxia on the brain may trigger neuronal damage and cell death due to an oxygen deficiency. The purpose of the current study was to investigate the histomorphological changes in the hippocampus, cerebral cortex, cerebellar cortex, and striatum of the rat’s brain following chronic hypobaric hypoxia. Fourteen albino rats were used for this investigation. The animals were exposed to chronic hypobaric hypoxia in the special decompression chamber at an altitude of 7000 m for 7 days. The histological analysis was conducted via toluidine staining and silver impregnation. DNA damage and cell apoptosis were assessed via Feulgen staining. The histochemical assessment revealed increased dark neurons in the hippocampus with cell swelling. Silver impregnation showed increased argyrophilic neurons in the cerebellar cortex, striatum, CA1 subfield of the hippocampus, and cerebral cortex. The cytochemical analysis determined the increased apoptotic cells with hyperchromatic condensation and pyknosis in the hippocampus subfields and cerebral cortex. In addition, it has been observed that hypoxia has resulted in small hemorrhages and perivascular edema within the cerebellar and cerebral cortex.The results indicate brain injury observed in the various parts of the brain towards hypobaric hypoxia, however, the hippocampus showed greater vulnerability against hypoxic exposure in comparison to the striatum, cerebellum, and cerebral cortex. These changes support our insights regarding brain intolerance under conditions of hypoxia-induced oxygen deficiency and its histomorphological manifestations.

Molecular and phenotypic distinctions of macrophages in tolerant and susceptible to hypoxia rats.

Individual hypoxia tolerance is a major influence on the course and outcome of infectious and inflammatory diseases. Macrophages, which play central roles in systemic inflammatory response and other immunity reactions, are subject to functional activation orchestrated by several transcription factors including hypoxia inducible factors (HIFs). HIF-1 expression levels and the lipopolysaccharide (LPS)-induced systemic inflammatory response severity have been shown to correlate with hypoxia tolerance. Molecular and functional features of macrophages, depending on the organisms resistance to hypoxia, can determine the severity of the course of infectious and inflammatory diseases, including the systemic inflammatory response. The purpose is the comparative molecular and functional characterization of non-activated and LPS-activated bone marrow-derived macrophages under normoxia in rats with different tolerance to oxygen deprivation. Hypoxia resistance was assessed by gasping time measurement in an 11,500 m altitude-equivalent hypobaric decompression chamber. Based on the outcome, the animals were assigned to three groups termed 'tolerant to hypoxia' (n=12), 'normal', and 'susceptible to hypoxia' (n=13). The 'normal' group was excluded from subsequent experiments. One month after hypoxia resistance test, the blood was collected from the tail vein to isolate monocytes. Non-activated and LPS-activated macrophage cultures were investigated by PCR, flow cytometry and Western blot methods. Gene expression patterns of non-activated cultured macrophages from tolerant and susceptible to hypoxia animals differed. We observed higher expression of VEGF and CD11b and lower expression of Tnfa, Il1b and Epas1 in non-activated cultures obtained from tolerant to hypoxia animals, whereas HIF-1α mRNA and protein expression levels were similar. LPS-activated macrophage cultures derived from susceptible to hypoxia animals expressed higher levels of Hif1a and CCR7 than the tolerant group; in addition, the activation was associated with increased content of HIF-1α in cell culture medium. The observed differences indicate a specific propensity toward pro-inflammatory macrophage polarization in susceptible to hypoxia rats.

Morphological and molecular-biological features of glioblastoma progression in tolerant and susceptible to hypoxia Wistar rats

Hypoxia is a major pathogenetic factor in many cancers. Individual resistance to suboptimal oxygen availability is subject to broad variation and its possible role in tumorigenesis remains underexplored. This study aimed at specific characterization of glioblastoma progression in male tolerant and susceptible to hypoxia Wistar rats. Hypoxia resistance was assessed by gasping time measurement in an 11,500 m altitude-equivalent hypobaric decompression chamber. Based on the outcome, the animals were assigned to three groups termed ‘tolerant to hypoxia’ (n = 13), ‘normal’, and ‘susceptible to hypoxia’ (n = 24). The ‘normal’ group was excluded from subsequent experiments. One month later, the animals underwent inoculation with rat glioblastoma 101.8 followed by monitoring of survival, body weight dynamics and neurological symptoms. The animals were sacrificed on post-inoculation days 11 (subgroup 1) and 15 (subgroup 2). Relative vessels number, necrosis areas and Ki-67 index were assessed microscopically; tumor volumes were determined by 3D reconstruction from histological images; serum levels of HIF-1α, IL-1β, and TNFα were determined by ELISA. None of the tolerant to hypoxia animals died of the disease during observation period, cf. 85% survival on day 11 and 55% survival on day 15 in the susceptible group. On day 11, proliferative activity of the tumors in the tolerant animals was higher compared with the susceptible group. On day 15, proliferative activity, necrosis area and volume of the tumors in the tolerant to hypoxia animals were higher compared with the susceptible group. ELISA revealed no dynamics in TNFα levels, elevated levels of IL-1β in the susceptible animals on day 15 in comparison with day 11 and tolerant ones. Moreover, there were elevated levels of HIF-1α in the tolerant animals on day 15 in comparison with day 11. Thus, the proliferative activity of glioblastoma cells and the content of HIF-1α were higher in tolerant to hypoxia rats, but the mortality associated with the tumor process and IL-1β level in them were lower than in susceptible animals. Specific features of glioblastoma 101.8 progression in tolerant and susceptible to hypoxia rats, including survival, tumor growth rates and IL-1β level, can become the basis of new personalized approaches for cancer diseases treatment in accordance to individual hypoxia resistance.

The Precautions Had Taken and Experiences Gained In a Hyperbaric Oxygen Therapy Center during COVID-19 Pandemic

Introduction: The aim of this study is to share our experiences with other hyperbaric clinics and healthcare professionals in their fight against other possible pandemics ahead. Hyperbaric oxygen therapy is a treatment performed in a fully enclosed pressure chamber, with multiple patients and an inside attendant nurse. During therapy, the probability of infecting each other and the inside attendant nurse is much higher than the external environment. The first detected case of the COVID-19 pandemic in Turkey which has spread around the world, was announced by the Ministry of Health on March 11. We had to take precautions in our hyperbaric oxygen therapy center. Methods: Before the pandemic, twelve patients were treated in a session, we carry out three sessions in a day. During pandemic six patients attended the same places in the same session. Patients shortened the hospital stay and avoided contact with other patients by coming during their own session. The sphygmomanometer and blood glucose meter were cleaned after each patient use to avoid cross-contact. At the end of each session, floors and seats inside the decompression chamber were wiped. Masks and tubes were washed with glutaraldehyde free high level disinfecting solution (CidexR OPA solution). The clothes were prepared by washing and ironing before each use every day [4]. COVID-19 PCR testing was requested from each new patient whose treatment was started and after the result was negative, the session was started. Patients with positive PCR test before the session were not treated. Results: Throughout the year 2021, a total of 796 HBO therapy sessions with an average of six patients were carried out, and we had six patients whose COVID-19 PCR test became positive in three separate sessions while receiving HBO therapy despite all the precautions. Conclusions: During the pandemic process, we continued to carry out hyperbaric oxygen therapy to emergently admitted and elective patients in our clinic by observing the social distance rules and using protective equipment during the pandemic. We observed successful results of risk and emergency planning.

Phagocytic activity of peripheral blood monocytes under &lt;i&gt;in vivo&lt;/i&gt; and &lt;i&gt;in vitro&lt;/i&gt; hypoxia conditions in tolerant and susceptible to oxygen deficiency rats

It is known that there are individual differences in resistance to hypoxia, which can determine the predisposition to the development and severity of various diseases, including infectious, inflammatory and tumor. There are no standardized methods for assessing resistance to hypoxia in experimental animals and humans without hypoxic exposure. The search for molecular-biological markers, identifying people with different resistance to oxygen deficiency under normoxic conditions or under moderate hypoxic exposure is undoubtedly efficient. It is possible that the assessment of the basic resistance to hypoxia can help to predict the development and severity of the course of diseases, the mechanisms of which are associated with oxygen deficiency. One of the methods to assess organism resistance to hypoxia without exposure in a decompression chamber or in highland conditions can be modeling hypoxia in vitro. The aim of the study was to characterize the phagocytic activity of peripheral blood monocytes in tolerant and susceptible to hypoxia Wistar rats under normoxic conditions, as well as after hypoxic exposure in vitro and in vivo. The resistance of rats to hypoxia was determined by the gasping time at an altitude of 11.500 m in a decompression chamber. A month after determining the resistance to hypoxia, one group of rats was placed in a decompression chamber at an altitude of 5,000 m for 1 hour to simulate the hypoxic state in vivo. Blood from the tail vein of the other group of rats was placed in 1% oxygen for 1 hour to simulate the hypoxic state in vitro. The phagocytic activity of peripheral blood monocytes was assessed by flow cytometry. It was demonstrated that phagocytic activity of monocytes did not differ in tolerant and susceptible to hypoxia rats under normoxic conditions. The phagocytic activity of monocytes after in vitro and in vivo hypoxic exposure was higher in tolerant to hypoxia animals in comparison to susceptible ones. An increase in the phagocytic activity of monocytes compared to normoxia conditions was observed only in tolerant rats under in vitro conditions of hypoxic exposure. The obtained results indicate that tolerant and susceptible to hypoxia organisms differ in the phagocytic activity of monocytes under conditions of oxygen deficiency, which can determine the course of inflammatory and tumor diseases. The data obtained will be the basis for further experimental investigations organism hypoxia resistance markers.

Black box of diving accidents: Contribution of forensic underwater experts to three fatal cases

Diving is a popular activity, largely practiced worldwide. Diving fatalities are not rare events, with drowning being the most common cause of death, followed by cardiac-related natural causes, immersion pulmonary edema and arterial gas embolism. In such cases, positive signs of drowning are not specific, depending also on the time of submersion of corpses. Moreover, drowning can be the terminal event. Over the years, measures to perform appropriate post-mortem examination in cases of diving fatalities were suggested, including the execution of post-mortem CT-scan, the use of a decompression chamber and the adoption of specific autoptic techniques. Although a multidisciplinary approach in forensic investigations concerning diving fatalities is discussed, poor cases focus on how the analysis of diving computer records and equipment can contribute to determining the cause of death. The present study shows how the cooperation between a forensic underwater expert and a forensic pathologist played a crucial role in interpreting radiological findings, guiding the autopsy and confirming/denying circumstantial data emerging from the investigations. Technical analysis of dive computer records and diving equipment is a fundamental step in the definition of the cause of death in diving fatalities. All diving computer data, not only those related to maximum depth and ascent’s profile, should be considered in detail, and the immersion graph carefully studied by both the forensic pathologist and the forensic underwater experts. The diving technical data can often play a crucial role in explaining any legal issue related to the circumstances of death, possibly leading the prosecutor to further investigation.

Napoleonic Governance in the Netherlands and Northwest Germany: Conquest, Incorporation, and Integration

At its height, the continental European possessions of Napoleonic France consisted of 130 departments. Among the last additions to the collection were the thirteen carved out of the Netherlands and north-west Germany and integrated, at least on paper, in 1810/11. Rule from Paris was short-lived: most of these departments were overrun by coalition troops in the course of 1813, though French forces clung on to Hamburg into the spring of 1814, when they finally surrendered after a devastating siege. Martijn van der Burg’s new book examines these departments, and thereby adds to a growing corpus of regional studies of Napoleon’s empire in recent decades. The territorial frame adopted by this book is its greatest strength. It allows for a comparison of integration policies in areas of vastly diverse histories and traditions. A similar methodology of cutting across multiple borders is adopted by Pierre Horn, in his book Le défi de l’enracinement napoléonien entre Rhin et Meuse, 1810–1814: L’opinion publique dans les départements de la Roër, de l’Ourthe, des Forêts et de la Moselle (published by Oldenbourg in 2016). With the Dutch departments examined by Van der Burg, the French confronted inhabitants already used to living together under a substantial territorial administration. The preceding phases under the Batavian Republic (1795–1806) and Kingdom of Holland (1806–1810) provided introductions to French-style governance. In contrast, the jumble of polities from which the north-west German departments were cobbled together were denied passage through any intervening decompression chamber. What made the whole area, Dutch and German, worth annexing from Napoleon’s perspective was his conflict with Britain. This was fought out economically, and the strategy of blockade and counter-blockade demanded direct control of the North Sea coast. The issue was how to best manage the annexation process.

Expression of protein phosphatase 4 in different tissues under hypoxia.

Relevant research data shows that there is a certain degree of energy metabolism imbalance in highland residents. Protein phosphatase 4 (PP4) has been found as a new factor in the regulation of sugar and lipid metabolism. Here, we investigate the differential expression of PP4 at a simulated altitude of 4,500 m in the heart, lung, and brain tissues of rats. A hypoxic plateau rat model was established using an animal decompression chamber. A blood routine test was performed by an animal blood cell analyzer on rats cultured for different hypoxia periods at 4,500 m above sea level. Quantitative polymerase chain reaction (qPCR) and western blot were used to detect the changes of protein phosphatase 4 catalytic subunit (PP4C) gene and protein in heart, lung, and brain tissues. The PP4C gene with the highest expression level found in rats slowly entering the high altitude area (20 m-2200 m-7 d-4500 m-3 d) was about twice as high as the low elevation group (20 m above sea level). The simulated high-altitude hypoxia induced an increase of PP4C expression level in all tissues, and the expression in the lung tissue was twice as expressed as heart and brain tissue at high altitude (P < 0.05). These results suggest that the PP4 phosphatase complex is ubiquitously expressed in rat tissues and likely involved in adaptation to or disease associated with high-altitude hypoxia.

Retro-fitment of an oxygen system in a transport aircraft of Indian Air Force: Decompression chamber trials to assess system functionality

The aeromedical concerns of sudden onset hypoxia and rapid decompression are an omnipresent threat to flight safety when flying over 10,000 ft. The concept of Time of Useful Consciousness (TUC) provides the aircrew a window to correct his predicament. The issues of hypoxia are mitigated in transport aircraft with cabin pressurization. However, the requirement of an oxygen system in these aircraft is considered essential in an emergency in case of cabin failure of cabin pressurization or rapid decompression, despite adequate TUC, as it provides immediate succor from anxiety, and subtle performance decrements, especially in VIP carriage or casevac roles. With this background, a requirement for retro-fitment of a functional oxygen system of a small transport ac of Indo-German origin into a pressurized medium-lift cargo aircraft of British Origin was envisaged. Toward this, ground-based simulator trials were conducted on the oxygen system to assess its functionality before undertaking flight trials in the aircraft. The assessment consisted of the ground trial of the test oxygen system in the Explosive Decompression Chamber with three experiment protocols. The experimentation involved exposure to a simulated altitude of 15,000 ft for 25 min and rapid decompression from 7000 to 15,000 ft. Physiological parameters, endurance, and flow of oxygen in the system were evaluated. The trial results indicated that the physiological parameters (heart rate, respiratory rate, oxygen saturation [SpO2], and end-tidal carbon dioxide [EtCO2]) were within normal limits during the entire duration of exposure to 15,000 ft and decompression from 7000 ft to 15,000 ft. In addition, the physiological parameters were also within normal limits during exposure to 1 min of simulated hyperventilation. Neither any subjective or objective symptoms of hypoxia were observed nor any appreciation of increased breathing resistance reported by the subjects. The endurance of the system in terms of delivering continuous oxygen flow at 15,000 ft was assessed to be 73 min. From the trials, it was inferred that the oxygen system in a single crew configuration could be used satisfactorily up to the operational ceiling altitude specified for the subject aircraft.

Tetrahydrocurcumin Ameliorates Acute Hypobaric Hypoxia-Induced Cognitive Impairment in Mice.

Ma, Xuexinyu, Yang Pan, Yuye Xue, Yao Li, Yan Zhang, Yani Zhao, Xingzhao Xiong, Jianbo Wang, and Zhifu Yang. Tetrahydrocurcumin ameliorates acute hypobaric hypoxia-induced cognitive impairment in mice. High Alt Med Biol. 23:264-272, 2022. Background: Hypobaric hypoxia (HH) impairs spatial learning and increases oxidative stress in rodents. We hypothesized that tetrahydrocurcumin (THC) may attenuate HH-induced neurobehavioral deficits by reducing HH-induced lipid peroxidation and increasing glycolytic activity. Materials and Methods: A C57BL/6 mouse model of acute high altitude brain injury was established using an animal decompression chamber for 24 hours. Cognitive and behavioral assessments were conducted using the Y-maze, open field, and Rotarod tests. We measured superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity; malondialdehyde (MDA) and reactive oxygen species levels; anti-neuronal core antigen (NeuN) immunoreactivity; and active occludin, hypoxia-inducible factor-1α, glucose transporter 1 (GLUT1), and GLUT3 expression levels in mice brain tissue. Results: The mice in the THC group showed improved cognitive impairment compared with those in the HH group in cognitive and behavioral tests, but failed to show improvement in the decline in coordination. The mice in the THC group were more effected than those in the HH group in demonstrating alleviation of hyperemia in cortical vessels and cell voids, and cells in the CA1 region were more closely arranged. Compared with those in the mice of the HH group, the concentration of MDA decreased significantly, the expression of occludin, NeuN immunoreactivity, and the activities of SOD and GSH-Px significantly increased in the mice of the THC group. An increase in GLUT1 expression was observed in HH-exposed animals (N group vs. HH group: 0.4 ± 0.08 vs. 0.60 ± 0.07, p < 0.05), and this increase was enhanced in animals treated with THC (HH group vs. THC group: 0.60 ± 0.07 vs. 0.82 ± 0.08, p < 0.05). Conclusions: THC improved cognitive impairment in mice, accompanied by reduced oxidative stress and increased GLUT1 protein levels.

Experimental demonstration of comminution with transcritical carbon dioxide cycles

A new comminution technology that can reduce energy consumption when compared to traditional grinding of rock is presented. The process is based on pulverization driven by transcritical CO2 cycles, resulting in tensile fracture inside the particle rather than compression from outside. Tensile strength of many rocks is approximately 10 times lower compared to compressive strength offering significant potential for saving energy. In this apparatus, comminution can occur over multiple cycles to enhance rock breakage without extracting and refeeding rock between cycles. The test rig depicts test conditions to capture and to recycle the CO2.Limestone is utilized as an example material in a lab-scale experimental apparatus. Within the apparatus, the temperature and pressure are raised to supercritical conditions. A rapid release of the CO2 into a decompression chamber results in an expansion of supercritical CO2 inside the pores and fractures rock from tension instead of compression. Results show a significant fraction of the limestone is comminuted in three consecutive CO2 pressure cycles. A majority of the resulting particles exhibit larger fragments from 5 mm to 13.2 mm. 6.2% of the feed material was directly transferred to fine material <300 μm without many intermediate progeny particles. Initial results indicate a larger ratio of the pressure before and after burst, and longer soak times aid pulverization. A single rock is also analyzed, where it is noted that breakage occurs along visible fractures, and this behavior is noted over consecutive cycles.

Apêndice Atrial Esquerdo: Anatomia, Função e Importância na Formação de Trombos

The left atrial appendage (LAA) is an extension of the left atrium (LA) and has complex anatomical structure and unique pathophysiological properties. The LAA functions as a decompression chamber during left ventricular (LV) systole and under increased left atrial pressure conditions. Despite previously being considered a relatively insignificant portion of the cardiac anatomy, the LAA has been highlighted as an important structure involved in the genesis of thrombus formation and thromboembolic events. With the recent development of percutaneous closure devices, LAA morphology assessments have become increasingly important. This article aims to describe LAA anatomy and morphology, function assessment parameters, thrombus diagnostic challenges, and the main imaging modalities, particularly transesophageal echocardiography.

Indicators of Hypoxia Tolerance as Determined by Cellular Elements of Rat Blood.

Although hypoxia tolerance is mainly determined genetically, it is important to study individual variability of animal organisms in order to identify the factors that underlie their tolerance to hypoxic exposure. We investigated blood cell counts and coagulograms in Wistar rats as predictors allowing the animal population to be split into hypoxia-tolerant and hypoxia-intolerant individuals. The validity of the specific predictors’ choice was proved by a coincidence between the population split in accordance with the detected individual parameters and the results of testing animals in a decompression chamber at a rarefaction corresponding to the “rise to an altitude” of 11500 m above sea level. Circulating blood cells were quantitatively assessed by eighteen indicators before and after hypoxic exposure. The differences between animals low-tolerant (LT), high-tolerant (HT), and medium-tolerant (MT) to hypoxia were determined by five indicators: white blood cell count (WBC), granulocyte count (Gran#), red blood cell count (RBC), reticulocyte count/percent (RTC), and mean corpuscular hemoglobin (MCH). The RBC, RTC, and MCH values in HT rats were significantly higher than in LT animals (by 1.4, 1.9, and 1.1 times, respectively). The WBC and Gran# values in HT rats were lower than in LT individuals. The hypoxia tolerance indices (HTI) were calculated using the original formula. It was established that in LT rats, the HTI ≤ 0.203, in HT rats ≥ 0.335, and in MT rats < 0.335 but > 0.203. After testing in a decompression chamber, the activated partial thromboplastin time (APTT), thrombin time (TT), and prothrombin time (PT) decreased, but the fibrinogen level increased. LT rats were characterized by the lowest APTT, TT, and PT values and the highest values of the fibrinogen level. Our results indicate that one of the most important mechanisms underlying a high hypoxia tolerance in rats consists in sustaining reciprocal relationships between the complex of RBC indicators, which tend to increase under hypoxia, and Gran# indicators, which tend to decrease after hypoxic exposure.

Protective effects of active compounds from on heart and brain of mice at simulated high altitude.

To investigate the active compounds from on the heart and brain of mice at simulated high altitude.Fifty healthy male adult BALB/c mice were randomly divided into normal control group, hypoxic model group, acetazolamide group, petroleum ether extract of (PESI) group and octacosan group with 10 mice in each group. Acetazolamide group, PESI group and octacosan group were treated with acetazolamide PESI (200 mg/kg) or octacosan by single tail vein injection, respectively. Except normal control group, the mice were exposed to a simulated high altitude of for in an animal decompression chamber. After the mice were sacrificed by cervical dislocation, the heart and brain were histologically observed by HE staining; superoxide dismutase (SOD) activity, total anti-oxidant capacity (T-AOC) and the content of malondialdehyde (MDA) in plasma, heart and brain tissues were detected by WST-1 method, ABTS method and TBA method, respectively; lactic acid and lactate dehydrogenase (LDH) activity in plasma, heart and brain tissues were detected by colorimetric method and microwell plate method, respectively; ATP content and ATPase activity in heart and brain tissues were detected by colorimetric method. PESI and octacosane significantly attenuated the pathological damages of heart and brain tissue at simulated high altitude; increased SOD activity, T-AOC and LDH activity, and decreased the contents of MDA and lactic acid in plasma, heart and brain tissues; increased the content of ATP in heart and brain tissues; increased the activities of Na-K ATPase, Mg ATPase, Ca ATPase and Ca-Mg ATPase in myocardial tissue; and increased the activities of Mg ATPase, Ca-Mg ATPase in brain tissue. PESI and octacosan exert anti-hypoxic activity by improving the antioxidant capacity, reducing the free radical levels, promoting the anaerobic fermentation, and alleviating the energy deficiency and metabolic disorders caused by hypoxia in mice.

A Case of Decompression Sickness Associated With PFO in a Dive Medical Officer

Abstract Current medical guidelines and regulations do not require routine examinations for the right-to-left shunt at divers. We present the case of a Polish Navy Dive Medical Officer (DMO) who more than 20 years ago suffered from decompression ilness - bends accompanied by cutis marmorata, numbness in one limb and mild vertigo. After treatment in decompression chamber all symptoms entirely resolved. Since then, despite of continuing diving, he experienced no decompression ilness symptoms. Twenty years later, then 52 years-old, the DMO was admitted as a patient to the Neurology Department at the Gdańsk Naval Hospital due to episodes of transient ischemic attacks. Contrast-enhanced transcranial Doppler ultrasound and transesophageal echocardiography were performed and he was diagnosed with severe right-to-left shunt across a patent foramen ovale (PFO). Retrospectively analyzing incident of DCI he suffered 20 years earlier, we suppose that it may have been caused by paradoxical air embolism associated with the RLS across the PFO, which was not diagnosed at the time of this incident yet. We conclude that although the risk of severe neurological, cutaneous or vestibular forms of DCI is very low, in order to increase diving safety, it seems to be reasonable to develop standards for initial PFO screening in certain groups of divers - professional divers, military divers and medical diving personnel. Contrast-enhanced transcranial Doppler ultrasound seems to be useful in RLS screening in divers. Using multi-compartment chambers equipped with an entry lock should be preferred for safe recompression treatment of divers.