Comparison of machine learning and Logistic regression model in predicting acute kidney injury after cardiac surgery: data analysis based on MIMIC-Ⅲ database / 中华危重病急救医学

Objective:To establish an acute kidney injury (AKI) prediction model in patients after cardiac surgery by extreme gradient boosting (XGBoost) machine learning model, and to explore the risk and protective factors for AKI in patients after cardiac surgery.Methods:All patients who underwent cardiac surgery in Medical Information Mart for Intensive Care-Ⅲ (MIMIC-Ⅲ) database were enrolled, and they were divided into AKI group and non-AKI group according to whether AKI developed within 14 days after cardiac surgery. Their clinical characteristics were compared. Based on five-fold cross-validation, XGBoost and Logistic regression were used to establish the prediction model of AKI after cardiac surgery. And the area under the receiver operator characteristic curve (AUC) of the models was compared. The output model of XGBoost was interpreted by Shapley additive explanations (SHAP).Results:A total of 6 912 patients were included, of which 5 681 (82.2%) developed AKI within 14 days after the operation, and 1 231 (17.8%) did not. Compared with the non-AKI group, the main characteristics of AKI group included older age [years: 68.0 (59.0, 76.0) vs. 62.0 (52.0, 71.0)], higher incidence of emergency admission and complicated with obesity and diabetes (52.4% vs. 47.8%, 9.0% vs. 4.0%, 32.0% vs. 22.2%), lower respiratory rate [RR; bpm: times/min: 17.0 (14.0, 20.0) vs. 19.0 (15.0, 22.0)], lower heart rate [HR; bpm: 80.0 (67.0, 89.0) vs. 82.0 (71.5, 93.0)], higher blood pressure [mmHg (1 mmHg ≈ 0.133 kPa): 80.0 (70.7, 90.0) vs. 78.0 (70.0, 88.0)], higher hemoglobin (Hb), blood glucose, blood K + level and serum creatinine [SCr; Hb (g/L): 122.0 (109.0, 136.0) vs. 120.0 (106.0, 135.0), blood glucose (mmol/L): 7.3 (6.1, 8.9) vs. 6.8 (5.7, 8.5), blood K + level (mmol/L): 4.2 (3.9, 4.7) vs. 4.2 (3.8, 4.6), SCr (μmol/L): 88.4 (70.7, 106.1) vs. 79.6 (70.7, 97.2)], lower albumin (ALB) and triacylglycerol [TG; ALB (g/L): 38.0 (35.0, 41.0) vs. 39.0 (37.0, 42.0), TG (mmol/L): 1.4 (1.0, 2.0) vs. 1.5 (1.0, 2.2)] as well as higher incidence of multiple organ dysfunction syndrome (MODS) and sepsis (30.6% vs. 16.2%, 3.3% vs. 1.9%), with significant differences (all P < 0.05). In the output model of Logistic regression, important predictors were lactic acid [Lac; odds ratio ( OR) = 1.062, 95% confidence interval (95% CI) was 1.030-1.100, P = 0.005], obesity ( OR = 2.234, 95% CI was 1.900-2.640, P < 0.001), male ( OR = 0.858, 95% CI was 0.794-0.928, P = 0.049), diabetes ( OR = 1.820, 95% CI was 1.680-1.980, P < 0.001) and emergency admission ( OR = 1.278, 95% CI was 1.190-1.380, P < 0.001). Receiver operator characteristic curve (ROC curve) analysis showed that the AUC of the Logistic regression model for predicting AKI after cardiac surgery was 0.62 (95% CI was 0.61-0.67). After optimizing the XGBoost model parameters by grid search combined with five-fold cross-validation, the model was trained well with no overfitting or overfitting. ROC analysis showed that the AUC of XGBoost model for predicting AKI after cardiac surgery was 0.77 (95% CI was 0.75-0.80), which was significantly higher than that of Logistic regression model ( P < 0.01). After SHAP treatment, in the output model of XGBoost, age and ALB were the most important predictors of the final outcome, where age was the risk factor (average |SHAP value| was 0.434), and ALB was the protective factor (average |SHAP value| was 0.221). Conclusions:Age is an important risk factor for AKI after cardiac surgery, and ALB is a protective factor. The performance of machine learning in predicting cardiac and vascular surgery-associated AKI is better than the traditional Logistic regression. XGBoost can analyze the more complex relationship between variables and outcomes, and can predict the risk of postoperative AKI more accurately and individually.

Clinical features and influencing factors of long-term prognosis in patients with tuberculous meningitis / 中华内科杂志

Objective:To investigate the clinical features and influencing factors of long-term prognosis of tuberculous meningitis(TBM), and to provide a recommendation for treatment and early intervention of TBM.Methods:Clinical data of TBM patients were retrospectively collected at Peking Union Medical College Hospital from January 2014 to December 2021. Patients who were followed-up more than one year were divided into two groups according to modified Rankin Scale (mRS). Risk factors associated with long-term prognosis were analyze by conditional logistic stepwise regression.Results:A total of 60 subjects were enrolled including 33 (55%) males and 27 (45%) females with age 15-79 (44.5±19.8) years. There were 30 cases (50%) complicated with encephalitis, 21 cases (35%) with miliary tuberculosis. The diagnosis was microbiologically confirmed in 22 patients (36.7%), including 5 cases (22.7%, 5/22) by acid-fast staining, 8 cases (36.4%, 8/22) by Mycobacterium tuberculosis (MTB) culture, and 20 cases (90.9%, 20/22) by molecular biology. The median follow-up period was 52(43, 66 ) months in 55 cases surviving more than one year. Among them, 40 cases (72.7%) were in favorable group (mRS 0-2) and 15 cases (27.3%) were in unfavorable group (mRS 3-6) with poor prognosis. The mortality rate was 20% (11/55). Elderly ( OR=1.06, P=0.048 ) , hyponatremia( OR=0.81, P=0.020), high protein level in cerebrospinal fluid (CSF) ( OR=3.32, P=0.033), cerebral infarction( OR=10.50, P=0.040) and hydrocephalus( OR=8.51, P=0.049) were associated with poor prognosis in TBM patients. Conclusions:The mortality rate is high in patients with TBM. Molecular biology tests improves the sensitivity and shorten the diagnosis time of TBM. Elderly, hyponatremia, high protein level in CSF, cerebral infarction and hydrocephalus are independent risk factors of long-term survival in TBM patients.

Mycobacterium tuberculosis latency-associated antigen Rv1733c SLP improves the accuracy of differential diagnosis of active tuberculosis and latent tuberculosis infection / 中华医学杂志(英文版)

BACKGROUND@#Differential diagnosis of active tuberculosis (ATB) and latent tuberculosis infection (LTBI) has been a challenge for clinicians in high TB burden countries. The purpose of this study was to improve the accuracy of differential diagnosis of ATB and LTBI by using fluorescent immunospot (FluoroSpot) assay to detect specific Th1 cell immune responses. The novel mycobacterium tuberculosis (MTB) latency-associated antigens Rv1733c and synthetic long peptides derived from Rv1733c (Rv1733c SLP) were used based on virulence factors early secreting antigen target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10).@*METHODS@#Fifty-seven ATB cases, including 20 pathogen-confirmed ATB and 37 clinically diagnosed ATB, and 36 LTBI cases, were enrolled between January and December 2017. FluoroSpot assay was used to detect the interferon γ (IFN-γ) and interleukin 2 (IL-2) secreted by the specific T cells after being stimulated with MTB virulence factors ESAT-6 and CFP-10, MTB latency-associated antigens Rv1733c and Rv1733c SLP. The receiver operating characteristic (ROC) curve was used to define the best cutoff value of latency-associated antigens in the use of differentiating ATB and LTBI. The sensitivity, specificity, predictive value, and likelihood ratio of ESAT-6 and CFP-10-FluoroSpot combined with latency-associated antigen in the differential diagnosis of ATB and LTBI were also calculated.@*RESULTS@#Following the stimulation with Rv1733c and Rv1733c SLP, the frequency of single IL-2-secreting T cells stimulated by Rv1733c SLP had the largest area under the ROC curve, which was 0.766. With a cutoff value of 1 (spot-forming cells [SFCs]/2.5 × 105 peripheral blood mononuclear cells) for frequency, the sensitivity and specificity of distinguishing ATB from LTBI were 72.2% and 73.7%, respectively. ESAT-6 and CFP-10-FluoroSpot detected the frequency and proportion of single IFN-γ-secreting T cells; the sensitivity and specificity of distinguishing ATB from LTBI were 82.5% and 66.7%, respectively. Combined with the frequency of single IL-2-secreting T cells stimulated by Rv1733c SLP on the basis of ESAT-6 and CFP-10-FluoroSpot, the sensitivity and specificity increased to 84.2% and 83.3%, respectively.@*CONCLUSION@#Rv1733c SLP, combined with ESAT-6 and CFP-10, might be used as a candidate antigen for T cell-based tuberculosis diagnostic tests to differentiate ATB from LTBI.

Effect of Baicalin on the Necroptosis of Mouse Colon Cancer in Vitro / 医药导报

Objective To investigate the effect of baicalin on CT26.WT cells of colon cancer in mice, and to discuss the cell death form. Methods CT26.WT cells were divided into four groups including of control group , routine cultured in fresh medium, the baicalin group, added with concentration of 100 μmol·L-1 baicalin, the z-VAD-fmk group, was added with final concentration of 20 μmol·L-1 z-VAD-fmk, and the combination group, added final concentration of 20 μmol·L-1 z-VADfmk,1 h before adding 100 μmol·L-1 baicalin. Then the inhibitory effect of baicalin on cell proliferation and cell viability were detected by CCK-8 method. The changes of nucleus were detected by DAPI staining, the ultrastructure of cells was observed by TEM, and the effect of baicalin on the expression of RIP3 gene and protein in cells was detected by QPCR method and Western blotting. Results Compared with control group, the differences of baicalin group and combination group had statistically significance (P<0.05) . cell death rate for control group was (10.54±0.19) ％ ,for baicalin group was (34.93±0.16) ％ ,for z- VAD group was (11.23±0.59) ％, and combination group was (23.27±1.20) ％ (P<0.01) . Compared with the normal control group, baicalin group showed nuclear concentration and fragmentation. there was obvious nuclear fragmentation in the combination group against baicalin group. The results of electron microscopy showed that the cells of baicalin were necrotic, cell swelling, mitochondria swelling and contents leaking. Baicalin group significantly up - regulated RIP3 mRNA expression (P < 0. 01) and enhanced RIP3 protein expression (P < 0. 05) . Conclusion Baicalin induces the necrosis of ct26. WT cells, and can significantly increase the gene and protein expression of RIP3.

Kinetics of serum HBsAg in chronichepatitis B patients with nucleos(t)ide analogues treatment / 基础医学与临床

Objective To summarize and analyze the dynamic change of HBsAg levels in patients with chronic Hepatitis B (CHB) after receiving nucleos(t)ide analogues (NAs) as antiviral treatment.Methods Patients who were performed quantitative Hepatitis B surface antigen(qHBsAg) from July 30, 2012 to December 30,2016 in Peking Union Medical College Hospital were retrospectively enrolled.qHBsAg, HBV DNA, HBeAg were collected and analyzed at baseline and at 192-week follow-up every 24 weeks.qHBsAg and HBeAg were assessed with chemiluminesent microparticle immuno assay(CMIA).HBV DNA was assessed with PCR and COBAS Amplicor.Results 60 patients were included.Patients in HBeAg-positive group had higher HBV DNA than that in HBeAg-negative group (P<0.05)at baseline and the two groups both were under detection limit after 48 weeks.BaselineqHBsAg in HBeAg positive-group and negative-group were (3.43±0.73) log10 IU/mL, (3.08±0.47) log10 IU/mL respectively.qHBsAg in HBeAg-positive group was higher than that in HBeAg negative-group on all follow-ups(P<0.05) except 48weeks.However on 168 weeks and 192 weeks, difference between the two groups was statistically significant(P<0.05).In HBeAg-positive group,quantitative HBeAg dropped significantly during antiviral treatment.Conclusions HBV replication can be suppressed in the process of long-term NAs treatment in CHB patients.However qHBsAg decline is not so obvious, which indicates that HBsAg cleavence is difficult,and long-term NAs therapy is still necessary.

Positive Rate of Different Hepatitis B Virus Serological Markers in Peking Union Medical College Hospital, a General Tertiary Hospital in Beijing / 中国医学科学杂志(英文版)

Objective s To investigate the positive rate of different hepatitis B virus (HBV) serological markers, and the demographic factors related to HBV infection.Methods We enrolled all patients tested for HBV serological markers, such as HBV surface antigen (HBsAg), HBV surface antibody (HBsAb), hepatitis B e antigen (HBeAg), hepatitis B e antibody (HBeAb), HBV core antibody (HBcAb), and HBV-DNA from July 2008 to July 2009 in Peking Union Medical College Hospital. The positive rate of each HBV serological marker was calculated according to gender, age, and de- partment, respectively. The positive rates of HBV-DNA among patients with positive HBsAg were also analyzed.Results Among 27 409 samples included, 2681 (9.8%) were HBsAg positive. When patients were divided into 9 age groups, the age-specific positive rate of HBsAg was 1.2%, 9.6%, 12.3%, 10.9%, 10.3%, 9.7%, 8.0%, 5.8%, and 4.3%, respectively. The positive rate of HBsAg in non-surgical department, surgical department, and health examination center was 16.2%,5.8%,and 4.7%, respectively. The positive rate of HBsAg of males (13.3%) was higher than that of females (7.3%, P=0.000). Among the 2681 HBsAg (+) patients, 1230 (45.9%) had HBV-DNA test, of whom 564 (45.9%) were positive. Patients with HBsAg (+), HBeAg (+), and HBcAg (+) result usually had high positive rate of HBV-DNA Results (71.8%, P=0.000).Conclusions Among this group of patients in our hospital, the positive rate of HBsAg was relatively high. Age group of 20-29, males, and patients in non-surgical departments were factors associated with high positive rate of HBsAg.

Early diagnosis values of C-reactive protein and procalcitonin for children with bacterial infectious pneumonia / 国际检验医学杂志

Objective To explore the early diagnosis value of C‐reactive protein (CRP) and procalcitonin (PCT ) for bacterial in‐fectious pneumonia of children .Methods A total of 101 children with bacterial infectious pneumonia ,64 children with non‐bacterial infectious pneumonia and 73 children with non‐infectious disease were selected in bacterial infectious pneumonia group ,non‐bacterial infectious pneumonia group and non‐infectious disease group respectively .Serum PCT and CRP levels were measured before treat‐ment in the three groups .With sputum culture results as gold standard for the diagnosis of bacterial infectious pneumonia ,the sensi‐tivity ,specificity ,positive predictive value ,negative predictive value ,Youden index and diagnostic accuracy of PCT ,CRP ,PCT /CRP series test and parallel test were calculated for bacterial infectious pneumonia diagnosis .Results The levels of PCT and CRP of children in bacterial infectious pneumonia group were significant higher than those of children in non‐bacterial infectious pneumonia group and non‐infectious disease group(P < 0 .05) .The sensitivity ,specificity ,positive predictive value ,negative predictive value , Youden index and diagnostic accuracy of PCT ( ≥ 0 .5 ng/mL as the best intercept point) for bacterial infectious pneumonia diagno‐sis were 0 .743 ,0 .719 ,0 .806 ,0 .639 ,0 .461 and 0 .733 .And the same values for PCT /CRP series test were 0 .604 ,0 .875 ,0 .884 , 0 .583 ,0 .479 and 0 .709 respectively .All the values were higher than those of children in non‐bacterial infectious pneumonia group and non‐infectious disease group except sensitivity .Conclusion The combination of PCT and PCT /CRP series test is ideal method for early diagnosis of bacterial infectious pneumonia with high sensitivity and specificity .

Extrahepatic manifestations of chronic hepatitis C virus infection: 297 cases from a tertiary medical center in Beijing, China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Chronic hepatitis C virus (HCV) infection can affect multiple organ systems and cause a variety of extrahepatic manifestations (EMs). We sought to assess the constituent ratio of EMs in Chinese patients with chronic HCV infection and identify the clinical and biological factors associated with EM.</p><p><b>METHODS</b>The medical records of 297 patients with chronic HCV infection were analyzed and demographic and epidemiological information was collected. The diagnosis of chronic HCV infection was based on positive anti-HCV combined with a positive HCV-RNA or at least two times of elevated aminotransferases attributable to HCV infection. Patients with HBV and/or HIV coinfection, autoimmune hepatitis, and history of alcohol abuse were excluded.</p><p><b>RESULTS</b>Sixty-two percent (184/297) of the patients had at least one EM, including fatigue (29.4%), type 2 diabetes mellitus (28.2%), renal involvement (12.5%), lymphadenopathy (9.6%), fever (9.4%), thyroid dysfunction (8.1%), and arthralgia (7.4%). Neuropathy, sicca syndrome, B-cell lymphoma, Raynaud's phenomenon, and lichen planus were rare. The mean age of patients with EM was older compared with those without EM.</p><p><b>CONCLUSIONS</b>EMs were common in Chinese patients with chronic HCV infection, particularly fatigue, type 2 diabetes, renal impairment, lymphadenophy, fever, and thyroid dysfunction. Older age was associated with EMs.</p>

Evaluation of the efficacy and safety of oral ibuprofen suspension in treatment of neonatal patent ductus arteriosus / 中国基层医药

Objective To observe the efficacy and safety of oral ibuprofen suspension in treatment of neonatal patent ductus arteriosus. MethodsFrom January 2006 to December 2009 in our hospital,128 cases with neonatal patent ductus arteriosus were accepted as the observation group,treated with oral Ibuprofen Suspension:from January 2003 to December 2005 in our hospital,92 cases with neonatal patent ductus arteriosus were accepted as the control group,treated with lndomethacin.Efficacy and adverse reaction of two groups were compared. ResultsThe closure of the observation group was better than the control group,and the incidence of adverse events was less than the control group,the differences between two groups were statistically significant(P＜0.05). ConclusionOral ibuprofen suspension in treatment of neonatal patent ductus arteriosus had satisfactory effect and less adverse reaction,it was worthy of clinic application.

Analysis of the risk factors for post-operative respiratory failure in elderly cardiac carcinoma patients / 中国基层医药

Objective To analyze the risk factors of post-operative respiratory failure in elderly cardiac carcinoma patients.Methods 28 elderly patients with respiratory failure (respiratory failure group) after the resection of cardiac carcinoma and 56 controls (control group) were studied.Preoperative respiratory function,the other complications,the site of incision,intravenous infusion,age of patients and smoking between two groups were compared by Logistic regression.Results Univariate risk factors included MVV<50% ,RV/TLC>50% ,FEV1<1.5L,PEF<70% ,DLCO<80% ,V75<70% ,the venous input,incision at chest.Multivariate logistic regression analysis identified that MVV<50% ,RV/TLC>50% ,FEV,<1.5 L,DLCO<80% were risk factors.Conclusion These results suggested that the patients with risk factors described above need more careful pre and post operative surveillance and management.

Effects of simulated weightlessness on bone marrow stromal cell count and osteogentic capacity of weight bearing bone in rats / 中国组织工程研究

BACKGROUND: Under specially physical environment, for example weightlessness, metabolism of bone tissue may have remarkable changes; however, osteoblast is a core of bone metabolism and bone formation, so it is very sensitive to changes of gravity environment.OBJECTIVE: To observe the effects of simulated weightlessness on bone marrow stromal cell count and osteogentic capacity of weight bearing bone in rats so as to reveal the mechanism of bone loss.DESIGN : Randomized pairing and controlled study.SETTING: College of Aerospace Medicine and Department of Pathology of Stomatology College, the Fourth Military Medical University of Chinese PLA.MATERIALS: A total of 20 adult healthy male SD rats were selected in this study. At the beginning of experiment, rats based on their body mass were randomly divided into control group and suspension group with 10 in each group. Alkaline phosphatase kit was provided by Beijing Zhongsheng Bioengineering High-technological Company.METHODS: The experiment was carried out in the Department of Pathology, Collage of Stomatology, the Fourth Military Medical University of Chinese PLA from November 1999 to July 2000. Rats were randomly divided into tail suspension group and control group with 10 in each group. Rats in the tail suspension group were given tail suspension for 28 days. Their heads maintained 30° low position, and their hindlimbs freely suspended and were not given weight loading. While, rats in the control group were fed normally. At the end of experiment, bone marrow stromal cells were obtained from femur for primary and transferring cultures.MAIN OUTCOME MEASURES: Cell counting and methylthianolyldiphenyl-tetrazolium bromide (MTT) assay were used to draw growth curve of cells in primary and transferring cultures and to measure activity of alkaline phosphatase and forming quantity of mineralized nodules in vitro.RESULTS : ① Activity of alkaline phosphatase: Activity of alkaline phosphatase of cells in the primary and transferring cultures in the suspension group was lower than that in the control group, and there was significant difference between them (P＜0.05). ② Forming quantity of mineralized nodules: Forming quantity of mineralized nodules in the suspension group was less than that in the control group, and there was significant difference between them (P＜0.05). ③ Cell growth: Growth curve of femoral stromal cells in primary and transferring culture manifested as S. Doubling time of cells in the suspension group was similar to that in the control group. ④ Amount of bone marrow stromal cells in femur: Amount of bone marrow stromal cells in primary culture in the suspension group was decreased as 50% as that in the control group (P＜0.05).CONCLUSION: Under simulated weightlessness, amount of bone marrow stromal cells decreases obviously; in addition, amount of osteoblast also decreases in weight bearing bone of hindlimbs and osteogentic capacity in vitro decreases simultaneously.

Effects of Tail Suspension on Renin-angiotensin System in Rat Myocardium / 航天医学与医学工程

Objective To study the changes of gene and protein expressions of key components of renin-angiotensin system (RAS) in myocardium of simulated weightless rats. Method Tail-suspended rats were adopted as animal model of simulated weightlessness. RT-PCR and Western blot analysis were performed to examine mRNA and protein expressions in rat myocardium, respectively. Result After 1 week tail-suspension,no obvious changes in angiotensinogen (AGT), angiotensin converting enzyme (ACE), 1a and 1b subtype of type 1 angiotensin Ⅱ receptor (AT 1aand AT 1b), key components of RAS in myocardium were observed. But after 4 weeks tail-suspension, the expressions of AGT mRNA and higher molecular weight band of AGT protein increased significantly (P

Protection Effects of a New Combined Anti-G Measure / 航天医学与医学工程

Objective To observe the protection effects of a new combined anti-G measure, which is composed of new bladder anti-G system, unassisted positive pressure breathing for G (PBG) and PHP maneuver. The problem of fatigue and pain when using this measure is also discussed. Method Each of the six fully qualified centrifuge subjects experienced 5 groups of centrifuge runs:1) relaxed +Gz tolerance without anti-G equipments and PHP maneuver;2) +Gz tolerance with FLH-x+KT-x;3) +Gz tolerance when performing PBG with FLH-x, KT-x, YM-x and TK-x;4) +6.5 Gz for 45 s using the same anti-G equipments as the 3rd group;5) +9.0 Gz for 15 s using the same anti-G equipments as the 3rd group and performing PHP maneuver. Result There were no incidents of G-induced loss of consciousness in this study. The protective effects of FLH-x+KT-x, PBG and PHP maneuver were 2.5 G, 1.67 G and 1.23 G respectively. All the subjects had accomplished the 6.5 G 45 s and 9.0 G 15 s runs with the new combined anti-G measure. The pain occured on neck, waist, arm and hands. Conclusion The new combined anti-G measure can provide enough anti-G protection for modern high performance aircraft. How to prevent the occurrence of neck injury and alleviate the pain induced by G when using this measure needs further investigation.

The changes of cardiovascular response to orthostatic stress caused by hypovolemia induced by weightlessness: a simulation study / 生物医学工程学杂志

We introduced the method of computer simulation in the studies of gravitational physiology. Based on work of Melchior (1994), we developed a mathematical model that can be used to stimulate cardiovascular responses to orthostatic stress (lower body negative pressure, LBNP). The model includes 7 sub-models: the redistribution of blood, the filling of left ventricle, left ventricle working, peripheral circulation, control of heart rate (HR), control of peripheral resistance and control of venous tone. Then we simulated the changes of blood pressure (BP) and heart rate during lower body negative pressure, and the results agreed well with the results of our human experiment. By using the developed model, we also simulated the effects of hypovolemia on the BP, HR and shock index during orthostatic stress. The simulation results indicate that the cardiovascular responses to orthostatic stress change significantly when the decrease of blood volume is more than 15% of the total blood volume. However, if the amount of the decrease of blood volume is less than 5% of the total blood volume, HR and BP could be maintained in normal range by the regulation of baroreflex during LBNP. Our simulation results suggest that hypovolemia may be the main cause of orthostatic intolerance induced by weightlessness.

Biomedical Problems of Artificial Gravity:Overview and Challenge / 航天医学与医学工程

The limitations of the currently used exercise-based counterm easures and the scientific rationale for the gravity-based countermeasures are a ddressed.Then,an overview of the physiological effects and requirements for th e two types of artificial gravity (AG),i.e.,the continuous AG provided by full -time spinning of the entire space system/habitat and the intermittent AG by i nco rporating a short-arm centrifuge into the spacecraft,is presented.Finally,sig nificance and challenge faced in future research on biochemical problems of arti ficial gravity are discussed

A STUDY OF THE ACCEPTABLE RATIO OF ADDED INSPIRATORY TO EXPIRA-TORY RESISTANCE / 解放军医学杂志

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