ABSTRACT
The Chilean workforce has over 200,000 people that are intermittently exposed to altitudes over 4000 m. In 2012, the Ministry of Health provided a technical guide for high altitude workers that included a series of actions to mitigate the effects of hypoxia. Previous studies have shown the positive effect of oxygen enrichment at high altitudes. The Atacama Large Millimeter / submillimeter Arrays (ALMA) radiotelescope operate at 5,050 m (Array Operation Site, AOS) and is the only place in the world where Pressure Swing Adsorption (PSA) and Liquid Oxygen technologies have been installed at a large scale. Here we discuss our experience using oxygen supplementation at ALMA, to prevent the malaise and/or risks associated with exposure at 5,050 m. Antenna operators experienced chronic intermittent hypobaric hypoxia (CIHH, shiftwork 8 days HA*6 days rest SL) over 4 years. Studies to define normal O2 saturation values were performed in OSF and AOS by continuous recording during the shift. The outcomes showed no differences between production procedures (PSA or Liquid oxygen) in regulating oxygen availability at AOS facilities. As a result, big-scale installations have difficulties reaching the appropriate oxygen concentration due to leaks in high mobility areas. In addition, the PSA plant requires adequation and maintenance to operate at a very high altitude.
La fuerza laboral chilena cuenta con más de 200.000 personas que están expuestas intermitentemente a altitudes superiores a los 4000 m. En 2012, el Ministerio de Salud entregó una guía técnica para trabajadores de altura que incluía una serie de acciones para mitigar los efectos de la hipoxia. Estudios anteriores han demostrado el efecto positivo del enriquecimiento de oxígeno en altitudes elevadas. El radiotelescopio Atacama Large Millimeter/submillimeter Arrays (ALMA) opera a 5.050 m (Array Operation Site, AOS) y es el único lugar en el mundo donde se han instalado tecnologías de adsorción por cambio de presión (PSA) y oxígeno líquido a gran escala. Aquí discutimos nuestra experiencia usando suplementos de oxígeno en ALMA, para prevenir el malestar y/o los riesgos asociados con la exposición a 5.050 m. Los operadores de antena experimentaron hipoxia hipobárica intermitente crónica (CIHH, trabajo por turnos 8 días HA*6 días descanso SL) durante 4 años. Se realizaron estudios para definir valores normales de saturación de O2 en OSF y AOS mediante registro continuo durante el turno. Los resultados no mostraron diferencias entre los procedimientos de producción (PSA u oxígeno líquido) en la regulación de la disponibilidad de oxígeno en las instalaciones de AOS. Como resultado, las instalaciones a gran escala tienen dificultades para alcanzar la concentración de oxígeno adecuada debido a fugas en áreas de alta movilidad. Además, la planta de PSA requiere de adecuación y mantenimiento para operar a gran altura.
Subject(s)
Humans , Oxygen/administration & dosage , Hypoxia/physiopathology , Blood Pressure/physiology , Models, Molecular , Desert , Absorption , Altitude , TelescopesABSTRACT
Objective:To observe the changes in hippocampus (CA1) and study the effect of chronic intermittent hypobaric hypoxia (CIHH) preconditioning on the memory and cognitive function of mice exposed to the whole brain irradiation.Methods:A total of 48 C57BL/6 male mice were randomly divided into control group, CIHH group, irradiation group (IR group) and CIHH+ IR group. For IR group, the whole brain of mice were irradiated with 10 Gy of 6 MV X-rays in a single fraction. Pretreatment with CIHH was performed by placing mice in a hypobaric chamber before radiation. The mirrors water maze experiment was performed in the four groups to observe the escape latency, the number of crossing platforms and the target quadrant residence time. Nissl staining was used to observe the changes of neuronal cells in hippocampal CA1 region. Immunofluorescence was used to detect the expression of microtubule-associated protein cells (DCX) in the subgranular zone (SGZ) of hippocampal dentate gyrus (DG) to evaluate neurogenesis.Results:After 30 days of whole brain irradiation, the escape latency of mice prolonged gradually, the frequency of crossing platform decreased ( P< 0.001), and the exploration time in the target quadrant decreased ( P<0.001). X-ray irradiation caused disorder of mice neuronal cells, degeneration and necrosis of neuronal cells, and decrease of DCX expression in CA1 region of mice. Compared with IR group, the CIHH+ IR group had shortened the escape latency, increased the frequency of crossing platform [(2.08±0.26) vs. (0.83±0.24), P<0.001], and also increased the exploration time in the target quadrant [(14.12±0.82)s vs. (7.42±0.73)s, P<0.001]. Pretreatment with CIHH also alleviated the deformation and necrosis of neurons in hippocampus, and increased DCX expression in CA1 region. Conclusions:Pretreatment of mice with CIHH plays a protective role in radiation induced hippocampal injury.
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Aim To investigate the effect of chronic intermittent hypobaric hypoxia (CIHH) on relaxation of thoracic aorta rings in male developing rats and the underlying mechanisms. Methods Male neonatal Spra-gue-Dawlay ( SD) rats were randomly divided into eight groups respectively: CIHH treatment group (CIHH), group of one-week post-CIHH (CIHH-pl), group of two-week post-CIHH ( CIHH-p2 ) , group of three-week post-CIHH (CIHH-p3 ) , control group for CIHH (Con), control group for CIHH-pl (Con-1), control group for CIHH-p2 ( Con-2) and control group for CIHH-p3 (Con-3 ). Rats in CIHH groups were put into a hypobaric chamber with the mother rats 1 ~ 3 days before the birth to get a hypobaric hypoxia exposure mimicking 3 km altitude for 42 days, 5 hours daily. Rats in control groups were kept in the same environment as CIHH rats except hypoxia exposure. After anaesthetized with pentobarbital sodium (50 mg • kg-1 i. p. ), the thorax of rats was opened and thoracic aorta rings were made. The artery rings were placed in the bath chamber filled with K-H solution, and the relaxation of artery rings was recorded under normoxia or a-cute hypoxia conditions, respectively. Results (1) Under normoxia condition, the acetylcholine ( ACh)-induced relaxation of thoracic aorta increased obviously in CIHH groups compared with corresponding Con groups ( P < 0. 05 ). ( 2 ) The enhancing effect of CIHH treatment on thoracic aorta could be maintained for at least three weeks (P < 0. 05). (3 ) Under acute hypoxia condition, ACh-induced relaxation of thoracic aorta in each group decreased obviously, but the decrease in CIHH groups was significant less than that in Con groups ( P < 0.05 ). (4) The enhancement of CIHH on relaxation of thoracic aorta could be reversed by indomethacin (Indo), a cyclooxygenase inhibitor, glibenclamide (Gli), a KATP blocker, and Tempo, a free radical scavenger. Conclusions CIHH augments endothelium-dependent relaxation in thoracic aorta of developing rats. Also, CIHH can antagonize the inhibition of acute hypoxia on relaxation of thoracic aorta. The enhancing effect of CIHH treatment may be related with the increase of prostacyclin, the opening of KATP and free radical production.
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Chronic intermittent hypobaric hypoxia (CIHH) is known to have an anti-hypertensive effect, which might be related to modulation of the baroreflex in rats with renal vascular hypertension (RVH). In this study, RVH was induced by the 2-kidney-1-clip method (2K1C) in adult male Sprague-Dawley rats. The rats were then treated with hypobaric hypoxia simulating 5000 m altitude for 6 h/day for 28 days. The arterial blood pressure (ABP), heart rate (HR), and renal sympathetic nerve activity (RSNA) were measured before and after microinjection of L-arginine into the nucleus tractus solitarii (NTS) in anesthetized rats. Evoked excitatory postsynaptic currents (eEPSCs) and spontaneous EPSCs (sEPSCs) were recorded in anterogradely-labeled NTS neurons receiving baroreceptor afferents. We measured the protein expression of neuronal nitric oxide synthase (nNOS) and endothelial NOS (eNOS) in the NTS. The results showed that the ABP in RVH rats was significantly lower after CIHH treatment. The inhibition of ABP, HR, and RSNA induced by L-arginine was less in RVH rats than in sham rats, and greater in the CIHH-treated RVH rats than the untreated RVH rats. The eEPSC amplitude in NTS neurons receiving baroreceptor afferents was lower in the RVH rats than in the sham rats and recovered after CIHH. The protein expression of nNOS and eNOS in the NTS was lower in the RVH rats than in the sham rats and this decrease was reversed by CIHH. In short, CIHH treatment decreases ABP in RVH rats via up-regulating NOS expression in the NTS.
Subject(s)
Animals , Male , Baroreflex , Physiology , Blood Pressure , Hypertension , Metabolism , Hypoxia , Kidney , Metabolism , Nitric Oxide Synthase Type I , Metabolism , Rats, Sprague-Dawley , Solitary Nucleus , MetabolismABSTRACT
RESUMEN Introducción En Chile, los trabajadores mineros están expuestos a condiciones laborales y ambientales particulares. Sin embargo, la normativa actual no considera estas condicionantes para evaluar el estado nutricional y riesgo cardiovascular de esta población. Objetivo Describir indicadores antropométricos de trabajadores mineros de la Región de Coquimbo, expuestos a un ambiente hipóxico hipobárico de manera crónica intermitente a una altitud moderada entre 0 a 2500 m. Metodología Se evaluaron 221 trabajadores a 0 m, 1600 m, y 2500 m. Se les midió peso, talla, pliegues cutáneos, perímetros de cintura y cuello. Con estas mediciones se determinó estado nutricional, composición corporal e indicadores antropométricos relacionados con riesgo cardiovascular. Resultados Los indicadores presentaron valores promedios superiores a la media nacional. Más aún, al separar los resultados por cota altitudinal, estos valores presentan un aumento a mayor altitud. Conclusión Este estudio mostró una alteración en los indicadores antropométricos, estado nutricional y composición corporal, con la altitud. Futuros estudios con un mayor tamaño muestral son necesarios para clarificar estos hallazgos.
ABSTRACT Introduction In Chile, miners are exposed to specific labor and environmental conditions. However, current regulations do not consider these conditions in the assessment of nutritional status and cardiovascular risk of this population. Objective To describe anthropometric indicators of miners in the Coquimbo Region who are exposed to chronic intermittent hypobaric hypoxia at moderate altitudes (between 0 and 2500 m). Methodology We evaluated 221 workers at 0 m, 1600 m, and 2500 m. We measured weight, height, skin fold, waist and neck circumference. With these measurements, we determined nutritional status, body composition and anthropometric indicators related to cardiovascular risk. Results The assessed indicators showed average values higher than national ones. Furthermore, values increased by altitude. Conclusion This study showed an alteration with the altitude in the anthropometric indicators, nutritional condition and body composition. Further studies with a high sample size are necessary to clarify these findings.
Subject(s)
Nutritional Status , Miners , Hypoxia , Body Composition , AnthropometryABSTRACT
Aim To confirm the inhibitory effect of chronic intermittent hypobaric hypoxia ( CIHH) on my-ocardial apoptosis induced by metabolism syndrome ( MS) , and to investigate its mechanism. Methods A rat model of MS induced by fructose was used. The blood pressure and the plasma content of glucose, tri-glyceride, cholesterol, and insulin after 12 h fasting were detected. HE stain were used to detect the cardi-ac structure. The TUNEL staining and activity of caspase-3 were used to detect the apoptosis of myocar-dium. The protein expression of Bcl-2 and Bax was detected by Western blot . Results Compared with the control rats, the blood pressure and the plasma content of glucose, triglyceride, cholesterol, and insu-lin were all increased in rats with MS. In rats with MS, the impairment of cardiac structure and the increase of apoptosis were also observed. The protein expression of Bcl-2 was significantly down-regulated, and that of Bax was significantly up-regulated in MS rats. The ratio of Bcl-2/Bax was also significantly decreased. Interest-ingly, CIHH could ameliorate all of the above issues. There was no significant difference between control group and CIHH group. Conclusion CIHH may im-prove the increased apoptosis in rats with MS via inhib-iting the mitochondrial pathway of apoptosis. This stud-y might provide new targets for therapy and the preven-tion of MS patients.
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Aim To investigate the effect of chronic intermittent hypobaric hypoxia ( CIHH) on the paeonol induced vasomotion of isolated rat ’ s thoracic aorta rings and its underlying mechanisms. Methods Spra-gue-Dawlay ( SD ) rats were randomly divided into 2 groups: control group ( CON ) and CIHH treatment group ( CIHH) . CIHH rats were exposed to hypoxia in a hypobaric chamber simulating 5 000 m altitude, 6 hours daily for 28 days. CON rats lived in the same en-vironment as CIHH animals except hypoxia. Organ bath technique was used to observe the effect of pae-onol on isolated thoracic aorta rings of rats. Results There were no significant differences of noradrenaline ( NE )- and KCl-induced contraction in thoracic aorta rings among CIHH and CON rats;CIHH enhanced va-sodilative effects of paeonol on isolated thoracic aorta rings of rats; the vasodilative effects on CIHH rats could be partly decreased by β-receptor blocker prop-ranolol,ATP-sensitive potassium channel ( KATP ) bloc-ker glibenclamide and NO synthase inhibitor L-NAME. Paeonol significantly inhibited NE-induced intracellular and extracellular calcium-dependent contraction in CIHH rats. Paeonol didn ’ t inhibit NE-induced con-traction by intracellular calcium release and its inhibi-tory effect couldn ’ t be blocked by glibenclamide in CON. Vasodilative effects of paeonol couldn ’ t be re-versed by indomethacin, a cyclooxygenase inhibitor, in CIHH and CON rats. Conclusion CIHH significantly enhances vasodilative effects of paeonol on isolated tho-racic aorta rings of rats. Besides promoting the signa-ling pathway of paeonol in CON, CIHH significantly enhances vasodilative effects of paeonol via activating KATP and inhibiting Ca2+ release from sarcoplasmic re-ticulum.
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Aim To observe the cardioprotection of chronic intermittent hypobaric hypoxia (CIHH) against ischemia/reperfusion injury in adult and young rats.Methods Adult and postnatal male Sprague-Dawley rats were divided randomly into four groups:control 28-day group (CON28),control 42-day group (CON42), CIHH 28-day treatment group (CIHH28), and CIHH 42-day treatment group (CIHH42). CIHH animals with maternal rats were put into a hypobaric chamber 2 days before birth to get 28 days and 42 days CIHH mimicking 3000 m altitude (P_B=525 mmHg,P_(O_2)=108.8 mmHg), 5 h daily, respectively.The control animals were kept in the same environment as CIHH rats with free access to water and food except hypoxic exposure. The isolated hearts were perfused in the Langendorff apparatus, undergoing 30 min global ischemia and 60 min reperfusion.Cardiac function was recorded continuously during the whole experiment. Parameters of left ventricular function included left ventricular developing pressure (LVDP), left ventricular end-diastolic pressure (LVEDP), maximal positive (+LVdp/dt) and negative (-LVdp/dt) velocity of left ventricular pressure, coronary flow (CF) and heart rate(HR).Results ① For adult rats, there was no significant difference in the parameters of left ventricular function between CIHH28 and CON28 groups. However, the recovery of cardiac function in CIHH42 rats was much better than that in CON42, including LVDP, LVEDP, ±LVdp/dt and CF (P<0.05). ② For young rats, the basic coronary flow (CF) in CIHH rats was significant higher than that in CON rats, while other parameters of cardiac function didn't change. The recovery of cardiac function in CIHH rats was much better than that in CON rats, including LVDP, LVEDP,±LVdp/dt and CF (P<0.05).Conclusion CIHH confers cardioprotection against ischemia/reperfusion injury in rat cardiomyocytes, which is predominant in CIHH42 group and significantly affected by the age of animals. Cardioprotective effects produce more easily in young rats by CIHH.
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AIM: To investigate the effect of chronic intermittent hypobaric hypoxia (CIHH) on the activity of adrenergic receptor(AR) in rabbit sino-atrial node (SAN) by intracellular recording.METHODS: New Zealand rabbits were randomly divided into three groups: control group (Con), 14 d CIHH treatment group (CIHH14) and 28 d CIHH treatment group (CIHH28). The CIHH rabbits were exposed to a simulated 5 000 m (oxygen 11.1%) hypobaric hypoxia in hypoxic chamber for 14 d or 28 d (6 h/d), respectively. SAN preparation was used and the transmembrane action potential was recorded by micropipettes. Isoproterenol hydrochloride (ISO, agonist of β-AR) and phenylephrine (PE, agonist of α_1-AR) at different concentrations (0.01, 0.1 and 1 μmol/L) were applied cumulatively to investigate the electrophysiological effect of the drugs on the rabbit SAN among Con, CIHH14 and CIHH28 groups, respectively. RESULTS: (1) CIHH didnt change the parameters of action potential of SAN recorded under basic condition. (2) ISO changed some parameters of AP significantly in a dose-dependent manner, including increases in the amplitude of AP (APA), maximal rate of depolarization (V_(max)), the velocity of diastolic (phase 4) depolarization (VDD), and rate of pacemaker firing (RPF). (3) The response of AP to ISO in CIHH rabbits was decreased significantly compared to that in Con animals. Under 1 μmol/L of ISO, the increases in VDD, RPF, APA and V_(max) in CIHH animals were smaller than those in Con animals (P<0.05). (4) No effect of PE (0.01, 0.1 and 1 μmol/L) on the parameters of action potential was observed. CONCLUSION: CIHH decreases the reactivity of β-AR, but has no effect on α_1-AR in SAN of rabbit.