ABSTRACT
Objective To test the effects of restuscitation with air or oxygen on the blood gas and cerebral superoxide dismutase (SOD) concentration in neonatal rats with experimental intrauterine asphyxia. Method Seventy-seven neonatal rats were randomly (random number) divided into three experimental groups: sham operation group (SHAM), air resuscitation group (AR), and oxygen resuscitation group (OR). In groups AR and OR, animal models of intrauterine asphyxia were established and then resuscitated with air (AR) or oxygen (OR) for 30min. Comparison was made between groups including the mortality 0 hour after resuscitation, and the levels of blood gas and cerebral SOD concentrations 0 h, 6 h and 24 h after resuscitation. Results Mortality of neonatal rats in SHAM group, AR group and OR group were 0 (0/24), 0 (0/26) and 3.7% (1/27), respectively (P ＞0.05). The average levels of blood PaO2 in OR group and AR group 0 h after resuscitation were (69.2 ± 8.2)mmHg and (55.5±10.3) mmHg,respectively (P=0.004). Blood pH and PaCO2 and BE levels in OR group 0 h after resuscitation were not significantly different from those in AR group (P＞0.05). Blood pH, PO2, PCO2and BE levels in OR group were also not significantly different from those in AR group 6 h and 24 hours after resuscitation. The average concentrations of cerebral SOD in OR group 0 h and 6 hours after resucitation were (38.3±9.8) U/mgprot and (8.6±3.6) U/mgprot, and those in AR group were (53.8± 10.6) U/mgprot and (13.0±4.6) U/mgprot, respectively (P = 0.003, 0.04). The cerebral SOD concentration in OR group 24 hours after resuscitation was not significantly different from that in AR group (P＞0.05). The cerebral SOD concentrations in SHAM group 0 h,6 h and 24 hours after resuscitation were much higher than those in OR group and AR group (P＜0.05). Conclusions Resuscitation with air is as good as pure oxygen in neonatal resuscitation, in respect of early mortality and improvement of acidosis in neonatal rats after intrauterine asphyxia. Resuscitation with air will generate less radical oxygen species than pure oxygen in neonatal rats after intrauterine asphyxia.
ABSTRACT
Objective: To observe the signal changes of blood-oxygen-level-dependent functional MRI (BOLD-fMRI) in brain tissue after inhalation of oxygen. Methods: Fifteen volunteers, 9 males and 6 females, were included in the present experiment. The fMRI was conducted using 1.5T Singna Double-gradient Super Conducting Magnetic Resonance Imaging system (GE Inc). Bold-fMRI scanning was conducted using GRE-EPI sequence and data analysis was done using SPM2 software. Meanwhile, the BOLD-fMRI T2 signal changes after 15 s and 6 min inhalation of pure oxygen were observed and compared with those after inhaling normal air. Results: No obvious activation of BOLD-fMRI was observed in the whole brain after inhaling normal air. Fifteen seconds after inhaling pure oxygen, the signal changes in the whole brain mainly manifested as the signal decrease in the gray matter, with average signal change being (- 0.041 ± 0.31)% in the gray matter and about (0.056 ± 0.26)% in the white matter; the changes were significantly different from those of the normal air group (P<0.001). Six minutes after inhaling pure oxygen, signal changes in the whole brain mainly manifested as the signal increase in the white matter, with the average signal change being about (0.015±0.365)% in the gray matter and (0.14±0.278)% in the white matter; the changes were significantly different from those of the normal air group (P<0.001). Conclusion: Inhaling oxygen for different time periods can cause different BOLD signal changes in brain tissues. BOLD T2 signal in grey matter is decreased after short-time inhalation and is increased in white matter after long-time inhalation.
ABSTRACT
Objective To provide the oxygen supply apparatus when the civil aviator and airforce pilot are inspected the hypoxia tolerance and altitude tolerance in the hypobaric environment.Methods Demand oxygen and contstant flow oxygen were supplied.Results The portable hypobaric oxygen supply apparatus can supply mixed oxygen below the altitude 8 000 m,and the oxygenous concentration of mixed oxygen was adjusted according to the altitude.The pure oxygen was supplied when the altitude was at 8 000～12 000 m.Conclusion The normal and emergency oxygen supply performance can fulfill the system physiological requirements.The portable hypobaric oxygen supply apparatus may be used by the persons engaging in special task on plateau also.
ABSTRACT
Objective:To observe the signal changes of blood-oxygen-level-dependent functional MRI(BOLD-fMRI)in brain tissue after inhalation of oxygen.Methods:Fifteen volunteers,9 males and 6 females,were included in the present experiment.The fMRI was conducted using 1.5T Singna Double-gradient Super Conducting Magnetic Resonance Imaging system (GE Inc).Bold-fMRI scanning was conducted using GRE-EPI sequence and data analysis was done using SPM2 software. Meanwhile,the BOLD-fMRI T_2 signal changes after 15 s and 6 min inhalation of pure oxygen were observed and compared with those after inhaling normal air.Results:No obvious activation of BOLD-fMRI was observed in the whole brain after inhaling normal air.Fifteen seconds after inhaling pure oxygen,the signal changes in the whole brain mainly manifested as the signal decrease in the gray matter,with average signal change being(-0.041?0.31)% in the gray matter and about(0.056?0.26)% in the white matter;the changes were significantly different from those of the normal air group(P