Müller cells are activated in response to retinal outer nuclear layer degeneration in rats subjected to simulated weightlessness conditions

A microgravity environment has been shown to cause ocular damage and affect visual acuity,but the underlying mechanisms remain unclear.Therefore,we established an animal model of weightlessness via tail suspension to examine the pathological changes and molecular mechanisms of retinal damage under microgravity.After 4 weeks of tail suspension,there were no notable alterations in retinal function and morphology,while after 8 weeks of tail suspension,significant reductions in retinal function were observed,and the outer nuclear layer was thinner,with abundant apoptotic cells.To investigate the mechanism underlying the degenerative changes that occurred in the outer nuclear layer of the retina,proteomics was used to analyze differentially expressed proteins in rat retinas after 8 weeks of tail suspension.The results showed that the expression levels of fibroblast growth factor 2(also known as basic fibroblast growth factor)and glial fibrillary acidic protein,which are closely related to Müller cell activation,were significantly upregulated.In addition,Müller cell regeneration and Müller cell gliosis were observed after 4 and 8 weeks,respectively,of simulated weightlessness.These findings indicate that Müller cells play an important regulatory role in retinal outer nuclear layer degeneration during weightlessness.

Influences of traditional Chinese medicine intervention on the bone growth and metabolism of rats with simulated weightlessness

Objective:To prohe into the influences of Chinese herbal compound on the growth and metabolism of weight-bearing bones of tail-suspended rats.Methods:Twenty-four male St) rats were randomly divided into blank conlrol group leighti.tail-suspended conlrol group(eight) and Chinese medicine treatment group leighti according to their weights.No treatment was done for the blank conlrol group.Double distilled water lavage was performed daily for the tail-suspended control group.On the basis of the tail-suspended rat model,the rats were given Chinese herbal compound lavage every day in Chinese medicine treatment group.This compound includes mulberry,Poria cocas and barbary wolfberry.etc.The lest cycle was four weeks.The rats were killed after the experiment.The right femoral bone was taken out for the physical measurements, and the left femoral bone was for the three-point beading test.The influences of Chinese herbal compound on femoral hone growth and biomechanicsl properties of simulated weightlessness rats were observed.Results:(1) After simulated weightlessness(tail-suspension),compared with the blank control group,all the physiological indexes of rat femoral bone decreased in tailsuspended group and Chinese medicine treatment group(P【0.05).The strength and rigidity of rat femoral bone decreased in tail-suspended group(P【0.01).the maximum load and rigidity coefficient also decreased with the inereasing toughness coefficient in the control group(P【0.01). i2i After the countermeasure of Chinese herbal compound,each biomcchanical indexes showed the tendency of increasing in Chinese medicine treatment group,and theses indexes were close to those of the blank control group(P【0.05),which indicated that(he bone loss caused by simulated weightlessness was improved.Conclusions:Chinese herbal compound for tonifying kidney could effectively prevent the bone loss and have some enhancements on the bone hiomechanical properties.

Effects of Simulated Weightlessness on Tight Junction Protein Occludin and Zonula Occluden-1 Expression Levels in the Intestinal Mucosa of Rats

This study investigated the tight junction（TJ） protein expression of the intestinal mucosa in a rat tail-suspension model under simulated weightlessness.Twenty-four Wistar rats were randomly divided into three groups：CON group（n=8）,control; SUS-14 d group（n=8）,tail-suspension for 14 days; SUS-21 d group（n=8）,tail-suspension for 21 days.Occludin and Zonula Occluden-1（ZO-1） expression levels were determined by immunohistochemical analysis and mRNA fluorescent quantitative PCR.Plasma levels of diamine oxidase（DAO） and d-lactate were determined using enzymatic spectrophotometry.Immunohistochemical results for occludin and ZO-1 showed disruption of the TJs in the intestinal mucosa in SUS-14 d and SUS-21 d groups.The expression levels of occludin and ZO-1 in SUS-21 d group were lower than those in SUS-14 d group,and significantly lower than those in CON group（Occldin：0.86±0.02 vs 1.01±0.03 vs 1.63±0.03 and ZO-1：0.82±0.01 vs 1.00±0.02 vs 1.55±0.01,P〈0.01）.Moreover,the levels of plasma DAO and d-lactate in SUS-21 d group were higher than those in SUS-14 d group,and significantly higher than those in CON group（DAO：27.58±0.49 vs 20.74±0.49 vs 12.94±0.21 and d-lactate：37.86±0.74 vs 28.26±1.01 vs 17.76±0.91,P〈0.01）.There were significant negative correlations between occludin or ZO-1 expression levels and DAO（r2=0.9014,r2=0.9355,P〈0.01） or d-lactate levels（r2=0.8989,r2=0.9331,P〈0.01）.Occludin and Zo-1 were reduced in intestinal mucosa both in mRNA and protein levels in the rat tail-suspension model.The significant negative correlations between expression levels of TJs and plasma levels of DAO or d-lactate support the hypothesis that intestinal permeability is increased due to a decrease in TJ protein expression during tail-suspension from 14 days to 21 days.

Changes of Stress-Strain Relationship of Rabbit Femoral Vein after Simulated Weightlessness

Objective: To observe the effect of simulated weightlessness on stress-strain relationship and the structural change of rabbit femoral vein. Methods: After seting up the Head-Down Tilt (-20°) (HDT) model to simulate weightlessness, 24 healthy male New-Zealand Rabbits were randomly divided into HDT-21d group, HDT-10d group and control group, with 8 in each. Femoral venous strips and rings were used to make uniaxial tensile test of the longitudinal and circumferential specimens of the vessels. At last we observed the microstructure of femoral vein wall in 3 groups. Results : With the increasing of load stress, both longitudinal and circumferential strains of vein samples from 3 groups increased significantly (P<0. 01). With the decrease of unload stress, strains decrease obviously (P<0. 01). The unloaded longitudinal and the circumferential strain from 3 groups increased much than those of the loaded. Under the same stress (longitudinal 0-2. 0 g, circumferential 0. 5-1. 0 g) , HDT-21d group and HDT-10d group increased obviously in tlie longitudinal or circumferential strain (load and unload) than control, and HDT-21d increased much than that of HDT-10d. The contents and structures of femoral vein walls of HDT-rabbits changed significantly. Some endotheli-um cells of femoral vein became short, columnar or cubic even fell off. Smooth muscle layers became thinner. Conclusion:The compliance of femoral venous increased significantly after weightlessness-simulation and increased much obviously after 21d-HDT than that of 10 d. The structure of femoral vein wall changed obviously. The changes may be one reason for the increase of femoral vein compliance.

EFFECT OF SIMULATED WEIGHTLESSNESS ON REPRODUCTION OF ADULT MALE RATS

Objective To study the effects of simulated weightlessness induced by tail-suspension on reproduction in adult male rats and its mechanisms. Methods Twenty Spraque-Dawley adult male rats were randomly divided into two groups: the experimental group and control group. Rats in the experimental group were tail-suspended for 14 days. After the treatment, the weight and morphology of testis, the quantity and quality of sperm, the level of serum testosterone and the apoptosis rate of testicular cells were observed. Results Compared with the control, the testicular weight, the quantity and quality of sperm, the level of serum testosterone significantly decreased (P<0.05) while the apoptosis rate of testicular cells significantly increased (P<0.05) in tail-suspended rats. In addition, hematoxylin and eosin (HE) staining showed that seminiferous tubules atrophied, spermatogenic cells decreased, seminiferous epithelial cells disintegrated and shed, and the lumina were azoospermic. Conclusion Simulated weightlessness induced by tail-suspension has a harmful effect on male reproduction of adult rats by increasing the apoptosis of testicular cells.

THE MORPHOLOGICAL CHANGES IN MUSCLE SPINDLES AND ALTERATIONS IN CELL ACTIVITY OF THE RATS' RED NUCLEUS AFTER 2 WEEKS' SIMULATED WEIGHTLESSNESS

Objective To study the morphological changes of soleus muscle spindle and electrical activity of neurons in Red Nucleus(RN) of the rat after 2 weeks' simulated weightlessness, and to reveal the interaction between proprioceptive inputs of muscle spindles and reciprocal alterations in RN under simulated weightlessness. Methods Twenty female rats were exposed to weightlessness simulated by tail-suspension for 14 days (SW-14d). Body weight(200-220g) matched female rats were control group(Con). The morphological changes in isolated muscle spindle of soleus muscle, the discharges of red nucleus neurons were observed after 14d tail-suspensions by silver staining and extracellular recording respectively. Results Compared with control group ,the nerve ending of muscle spindle in SW-14d was distorted, degenerated and dissolved; the diameters of intrafusal fibers and capsule in equatorial region of soleus muscle spindles were diminished(P<0.05). The spontaneous cell activity and discharge of RN neurons (spikes/s) induced by afferent firing from muscle spindles after injection of succinylcholine were reduced after 2 weeks' simulated weightlessness respectively (18.44±5.96 vs. 10.19±6.88, 32.50±8.08 vs. 16.86±5.97, P<0.01). Conclusion The degeneration of muscle spindle induced by simulated weightlessness may be one of the causes that led to alterations in discharges of RN.

Fos expression in the medullary visceral zone following transient decrease of blood pressure in rats under simulated weightlessness

Objective: To observe Fos expression after transient decrease of blood pressure in catecholaminergic neurons of the medullary visceral zone(MVZ) in simulated weightlessness rats. Methods: Simulated weightlessness was abtained by tail suspension for 4 weeks, and transient decrease of blood pressure was induced by intravenous injection of sodium nitroprusside. Fos expression in catechlaminergic neurons of MVZ were visualized by an immunohistochemical double-labeling technique with anti-Fos and anti-tyrosine hydroxylase (TH) antibodies. Results: The decrease of blood pressure in the simulated weightlessness rats resulted in Fos expression in many neurons of the medulla oblongata, and they were primarily localized in the MVZ. In the MVZ, Fos-positive neurons were concentrated in the nucleus of the solitary tract (NTS) and ventrolateral region of the medulla (VLM). On the other hand, the numbers of Fos-positive neurons in MVZ were smaller than that of control rats (treated with tail suspension or intravenous injection of sodium nitroprusside only). Although some TH-positive neurons were found to be Fos-positive, the proportion of TH/Fos double-labeled neurons was much lower than that of the control rats; intensity of TH-like immunoreactivity was also reduced. Conclusion: The decrease of Fos-positive neurons and proportion of catechlaminergic neurons expressing Fos protein may result from decrease of parasympathetic activity in the simulated weightlessness rats.

Effects of electrostimulation and administration of succinylcholine on the expression of Fos protein in mesencephalic periaqueductal gray matter of rats after simulated weightlessness

BACKGROUND： Expression of Fos in neurons of periaqueductal gray （PAG） is used to reflect the excitability. However, changes of expression of Fos in neurons of PAG are caused by injured electrostimulation after simulated weightlessness, and the relationship between pretreatment and injection of succinylcholine has not been determined yet. OBJECTIVE ： To investigate the changes of expression of Fos in PAG induced by injured electrostimulation pretreatment and injection of succinylcholine at 2 weeks after simulated weightlessness.DESIGN： Observational and controlled animal study.SETTING： Department of Physiology, Medical School, Xi＇an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education. MATERIALS： A total of 24 adult female SD rats, of clean grade and weighing 180-220 g, were selected in this study. METHODS： The experiment was completed in the Experimental Animal Center of Xi＇an Jiaotong University.① All rats were randomly divided into 2 groups according to body mass： simulated weightlessness group and control group with 12 in each group. And then, each group was also divided into 3 subgroups： electrostimulation group, succinylcholine-pretreatment group and succinylcholine-injection group with 4 in each subgroup. ②The model of weightlessness was simulated by tail-suspended female rats, which were described and modified by Cheng Jie. Rats in normal control group were given the same interventions as simulated weightlessness group except for tail-suspended. ③ Experimental method： The rats in electrostimulation group were given nociceptive stimulus by a pair of subcutaneous electrodes inserted into 1 and 5 claw of left hindlimb. The stimulus （current： 10 mA; duration： 1 ms; interval： 1 s） lasted for 30 minutes. The rats in succinylcholine-pretreatment group received stimulus after intravenous administration of succinylcholine, rats in succinylcholine-injection group were not given stimulus, just received succinylcholine. ④ All rats were perfused and fixed after 2 hours from the end of stimulation. The brains were removed, and serial frozen sections of midbrain were stained using immunocytochemical method, observed and taken photos under light-microscope. The number and morphological characters of Fos-immunoreactive （Fos-IR） neurons in ventrolateral part of PAG were investigated. MAIN OUTCOME MEASURES： The alterations in number and morphological characters of Fos-IR neurons in ventrolateral PAG of all rats.RESULTS： A total of 24 rats were involved in the final analysis. ① The morphological changes of Fos-IR neurons： The expressions of Fos in ventrolateral part of PAG were observed in both control and simulated weightlessness groups rats after being given nociceptive stimulus. As compared with control group, Fos-IR neurons in simulated weightlessness group were dyed lightly, cellular integrity was impaired, and cellular verge was unclear. ② The numbers of Fos-IR neurons： In control group, the numbers of Fos-IR neurons in ventrolateral part of PAG in simulated weightlessness group were obviously lower than succinylcholine-pretreatment group, but obviously higher than succinylcholine-injection group （46.94±3.38, 71.06±8.96 and 35.04±4.62, respectively, P 〈 0.05）. In 14-day simulated weightlessness group, the numbers of Fos-IR neurons in electrostimulation group were also obviously lower than succinylcholine-pretreatment group, and obviously higher than succinylcholine-injection group （27.77±3.27, 32.91±2.99 and 11.75±1.00, respectively, P 〈 0.05）. The numbers of Fos-IR neurons in all subgroups in control group were obviously higher than those subgroups in simulated weightlessness group. Compared with electrostimulation group, the percentage of expression of Fos in ventrolateral part of PAG responsed to nociceptive stimulus after administration of succinylcholine （SCH） was increased to 51.83% in control group and 18.51% in simulated weightlessness group.CONCLUSION ：① The expression of Fos in neurons in ventrolateral part of PAG were increased by the pretreatment of SCH before nociceptive stimulus.② Nociceptive stimulus could increase the expression of Fos in neurons in ventrolateral part of PAG. ③ The numbers of Fos-IR neurons in ventrolateral part of PAG were decreased obviously after 2-week simulated weightlessness.

Effect of long-term weightlessness on retina and optic nerve in tail-suspension rats

AIM： To evaluate the effect of long weightlessness on retina and optic nerve in suspension （TS） rats. -term tail METHODS： A stimulated weightlessness model was established by suspending rats tail. After 12wk, the ultrastructure and the number of optic nerve axons were observed by transmission electron microscope. The number of survival retinal ganglion cells （RGCs） was calculated by fluorescent gold retrograde labeling. Retina cells apoptosis was detected by TUNEL staining. The function of optic nerve and retina was evaluated by the visual evoked potential （VEP） and oscillatory potentials （Ops）. RESULTS： The optic nerve axons were swollen and sparsely aligned, and the lamellar separation and myelin disintegration occurred after 12wk in TS rats. The density of optic nerve axons was 32.23±3.92 （ ys 37.43±4.13, P= 0.0145）, the RGCs density was 1645 ±46 cells/mm^2 （vs 1867±54 cells/mm^2 F=0.0000）, the incidence rate of retinal cells apoptosis was 5.38%±0.53% （ vs 4.75%±0.54%, P= 0.0238）, the amplitude of VEP-P100 was 15.43±2.14 μV （vs 17.67±2.17 μV, P=0.0424）, the latency of VEP-P100 was 69.05v5.34ms （vs 62.43±4.87ms P=0.0143） and the sum amplitude of Ops was 81.05±8.34 μV （Ys 91.67± 10.21 μV, P=0.0280） in TS group and the control group, respectively. CONCLUSION： Long-term weightlessness can induce the ultrastructural changes and functional depress of the optic nerve, as well as retinal cell damages in TS rats.

Distribution of ^3H—nicotine in Rat Tissues Under the Influence of Simulated Microgravity

Rat tail suspension offers a useful model to reproduce physiologic responses to weightlessness.The present study was conducted in the head-down-tilt(HDT) rat model to assess changes in metabolism of body tissues employing 3H-nicotine. Twelve male rats were used in the study. Half of the rats were tail suspended at 30°for two weeks on a 12/12 light/dark cycle. During this period,body weight, food and fluid intakes were measured. At term, animals were anesthetized and injected IV withe a solution contaming 4 microuries of micotine. After 90 min the animals were sacrificed, exsanguinated and tissues (brain,blood,trachea,salivary gland,lung,heart,esophagus,spleen, kidneys and testes) were harvested. The distribution of 3H-nicotine per gram of each tissue was determinded and ealeulated as percent of total injected radioactivity. Final body weights of suspended ammals were significantly (P < 0.0 5) lower than those of eontrols(309±21 vs 350±11g). 3HNicotine waw retained in greatest amounts by the kindneys, followed inorder by salivary glands, spleen, and gastrointestinal tissues. compared to non-suspended control, the tissue retention of nicotine in suspended animals was decreased in the following tissues:esphyagus (25 %), aorta (25%). fundus (25%), trachea (22%), adrenals (18%), spleen (17 %), and pancreas (12 %). The decreased retention of mcotine in tissues from suspended animals may be indicative of the fluid shifts and changes in blood flow to those tissue beds. The lack of differnces in nicotine retention in liver and kidney between control and suspended groups may implicate a normal metabolic function of these organs even under simulated weightlessness.

EFFECT OF SIMULATED WEIGHTLESSNESS ON THE RESPONSE CHARACTERISTICS OF HUMAN BRAIN

In order to systematically investigate the effects of simulated weightlessness on thefunction state of human brain, 15° head-down tilt (HDT) was used to simulate weightless-ness, and the response changes of event-related EEG power spectra, medium-frequencysynchronous potentials and slow-waves were examined in the present study. It was foundthat HDT had characteristic effects on the above EEG responses, suggesting that the ef-fects mainly occurred in the brain’s regulatory system, therefore, resulting in changes ofthe brain function state.

长期模拟失重实验中医证候诊断量表的研究

目的制订适用于长期模拟失重实验受试者整体健康状态评价的中医证候诊断量表,并对其信度与效度进行初步评价。方法本研究基于对长期航天飞行不同阶段中的人体中医病机的认识,通过文献调研结合专家咨询的方法制订量表。采用重测信度和内部一致性系数来检验量表信度;进行为期90 d的头低位卧床实验,采用项目分析和因子分析法评价量表的效度,采用旋转成分矩阵分析各条目与维度间的相关性。结果长期模拟失重实验中医证候诊断量表包含8个维度、57个条目。信度分析结果:30名受试者前后两次量表评分总分相关系数为0.889,表明量表的稳定性很高;量表的克龙巴赫α系数为0.934,表明量表内部一致性非常好;分半信度校正后为0.858,表明量表的信度很高。效度分析结果:57个条目在高分组和低分组的差异均有统计学意义(P<0.01),各条目与量表总分的皮尔逊相关系数均>0.4(P<0.001);采用主成分因子分析法提取8个公因子,累积贡献率为55.293%;旋转成分矩阵分析结果经医理分析和专家反馈显示,与初始8个维度的重合度高达87.5%,表明量表的结构效度良好。结论量表具有良好的信度和效度,能够进行中医证候诊断,适用于长期模拟失重实验,可为受试者主观感受的评价提供客观量化新方法。

非接触式生理心理检测在长期模拟失重效应分析中的应用研究

目的在模拟失重生理效应场景下,构建基于面部视频的非接触式生理心理检测模型,探索长期模拟失重生理效应分析的非接触式心率和负性心境状态检测新方法。方法搭建可见光和热红外视频融合分析的非接触式生理心理数据采集系统,采集“地星二号”90 d头低位卧床实验中受试者生理心理相关数据,构建基于图卷积网络面部多区域特征融合的非接触式心率检测模型和考虑数据可靠性的非接触式负性心境状态检测模型,并以指夹式心率和POMS-SF量表为标签,验证模型的有效性。结果研究结果显示,非接触式心率检测模型的Bland-Altman图差值平均数为-1.26 bpm,且96.3%的误差值检测数据处于95%一致性区间内,模型检测的心率与指夹式心率有较高的一致性;非接触式负性心境状态检测模型对于紧张、压抑、愤怒、疲劳的检测准确率均超过0.85,且心率、AU06、眼部视线、头部姿态对心境状态检测的影响显著。结论非接触式生理心理检测方法不仅能够用于长期模拟失重的生理效应分析,还可为未来长期空间飞行的航天员在轨健康保障提供新途径。

溅射工艺时间对不同靶材溅射速率的影响

为了研究溅射工艺时间对不同靶材溅射速率的影响,以铜、铝、二氧化硅、氧化锌4种靶材为研究对象,获得不同溅射工艺时间下沉积薄膜厚度。根据靶材的导热情况和溅射时腔内的温度变化建立数学模型,采用Matlab软件模拟出靶材表面温度随溅射工艺时间的变化。结果表明,随着溅射工艺时间的延长,铜、铝等金属靶材的溅射速率几乎没有改变,而氧化锌和二氧化硅等靶材出现“溅射失重”现象,原因可能与靶材的导热性能和键能有关。

麻栎木热解过程的热质变化行为及其动力学

为了解麻栎木热解特性,采用TGA/DSC同步热分析仪对其热解过程的失重机制和热行为进行了研究,采用Flynn-Wall-Ozawa(FWO)法和Kissinger-Akahira-Sunose(KAS)法计算了该过程的表观活化能,通过Malek方法得到了麻栎木热解最概然机理函数。研究结果表明:麻栎木的热解过程分为干燥、预热、挥发分析出和炭化4个阶段,在挥发分析出阶段质量损失最大,达71.24%。麻栎木热解过程既包括吸热反应也包括放热反应,随着升温速率的增加,其TG曲线和DTG曲线均向高温方向移动。FWO法和KAS法计算得到的表观活化能(E)范围分别为226.79~258.17 kJ/mol和229.22~260.8 kJ/mol,相关系数(R^(2))均在0.94以上,E随转化率变化趋势一致。Malek法计算结果表明:麻栎木热解机理在转化率小于0.5时符合三维扩散机理(Jander方程);在转化率大于0.5时符合成核生长机理(Avrami-Erofeev方程,n=3/2)。

中性浮力水下机械臂关键技术研究

水下机械臂可为航天员中性浮力训练提供转运和定点支持功能,提高训练过程的连贯性和效率。针对水下密封、中性浮力配平和防腐蚀3项水下机械臂关键技术,提出了采用多重冗余密封、浮力块与关节外壳赋形设计的技术方案,选用钛合金和双相不锈钢材料提升了机械臂的防腐蚀性能。研制的水下机械臂产品参与出舱活动训练已超过2年,最长在水下连续使用超过226天,工作状态良好,保证了空间站出舱活动水下试验的质量与有效性。

利用玻璃渣替代安山岩骨料制备耐热混凝土的试验研究

采用普通硅酸盐水泥、安山岩粗细骨料、粉煤灰、玻璃渣制备了耐热混凝土,研究了不同掺量玻璃渣替代部分粗骨料(0、5%、10%)对耐热混凝土在不同温度热处理(常温25℃,110℃烘干,300℃、500℃、700℃、900℃煅烧)前后对混凝土的尺寸、质量、抗压强度、热导率的影响,评价了混凝土的耐热性能,并分析了混凝土在高温热处理过程中的耐热损伤机理。研究结果表明:随温度从25℃升高至900℃,混凝土逐渐脱水脱碳而失重,密度逐渐降低,热导率也相应减小。混凝土的质量和密度可以用来评价混凝土的导热率。随热处理温度的升高,混凝土先收缩后膨胀,抗压强度则随温度的升高而先增加后减少,在300℃时达到最大值,此时混凝土的收缩变形也最小。玻璃渣取代粗骨料比例越高,混凝土变形越大,失质量越大,导热率越小,混凝土抗压强度越低,但整体差异不大。验证了采用玻璃渣取代部分骨料制备耐热混凝土的可行性。

失重和重力条件液态金属绕流管束对流传热特性对比

液态金属绕流管束对流换热能力强,其应用有助于换热设备小型化,是空间动力反应堆主换热器设计的较好选择。失重是空间环境的典型特征,失重和重力条件下液态金属绕流管束流动传热特性的异同尚不清楚,阻碍了液态金属用于空间反应堆的发展进程。为此,通过雷诺时均数值模拟方法,对比研究了失重和重力条件下液态金属绕流管束湍流传热特性,获得了局部温度与速度分布,得到了流动传热性能变化规律。结果表明:竖直向下流动时,液态金属对流传热性能在失重和重力条件下表现不同;重力条件下浮力影响了流场和温度场,相比失重条件,阻力和换热性能最大偏差约10%。

CKIP-1对模拟失重诱导的成骨细胞微丝变化的影响

【目的】探讨酪蛋白激酶结合蛋白1(CKIP-1)对模拟失重诱导的成骨细胞微丝变化的影响。【方法】选择小鼠成骨样细胞株(MC3T3-E1)进行研究,借助回转器模拟微重力环境,通过慢病毒感染构建CKIP-1过表达模型,将细胞分为a组(微重力组)、b组(空载慢病毒及微重力组)、c组(CKIP-1过表达慢病毒及微重力组)、d组(CKIP-1过表达慢病毒组)。使用FITC标记的鬼笔环肽对细胞进行荧光染色,在激光共聚焦显微镜下观察细胞微丝的变化,同时通过qRT-PCR技术测定CKIP-1 mRNA、ALP mRNA及RUNX2 mRNA的表达情况。【结果】每组细胞的微丝结构均呈现不同程度的解聚,而且张力纤维可见紊乱排列,并数量下降,以CKIP-1过表达慢病毒感染的成骨细胞模拟微重力组改变最为明显。c组、d组CKIP-1 mRNA表达水平高于a组、b组,差异有统计学意义(P<0.05)。c组成骨细胞RUNX2 mRNA、ALPL mRNA表达水平均低于a组、b组、d组,差异有统计学意义(P<0.05)。a组、b组、d组成骨细胞RUNX2 mRNA、ALPL mRNA表达水平比较,差异无统计学意义(P>0.05)。【结论】CKIP-1过表达可能会进一步加重微重力条件下成骨细胞骨架微丝的解聚,进而抑制成骨细胞增殖及分化。

CO_(2)分压对S135钢在CO_(2)/H_(2)S共存体系中腐蚀行为的影响

为了给井下油气管材的选择和腐蚀预测模型的建立提供理论依据,利用高温高压反应釜进行S135钢在CO_(2)/H_(2)S共存体系中的腐蚀模拟试验,采用失重法、恒载荷法、X射线衍射(XRD)、扫描电镜(SEM)、能谱(EDS)、三维轮廓扫描仪等手段研究了CO_(2)分压对S135钢在温度100℃、CO_(2)/H_(2)S共存体系中腐蚀行为的影响及规律。结果表明,随CO_(2)分压升高,S135钢的腐蚀速率增大,屈服强度损伤加剧,CO_(2)分压为5,10,15,20 MPa时,其屈服强度(σs)损伤率分别为1.4%、3.6%、4.5%和15.9%;抗拉强度(σb)损伤率分别为1.2%、3.4%、5.2%和15.4%。S135钢在低CO_(2)分压下发生全面腐蚀,随CO_(2)分压增大发展为以全面腐蚀为主,辅以局部腐蚀。应力腐蚀裂纹在萌生阶段以局部阳极溶解作用(点蚀)为主,随CO_(2)分压增大应力腐蚀裂纹更易生长,应力腐蚀敏感性增加,加剧了基体的腐蚀进程。