模拟失重对人尿皮质醇,17—OHCS及钙离子昼夜节律的影响

本实验是观察模拟失重下(头低位-6°卧床)时人尿皮质醇、17-OHCS 及钙离子昼夜节律的变化。采用余弦法(COSinor)分析,我们首次观察到模拟失重能引起人体内分泌昼夜节律去同步化。表现为三相指标相位后移,振幅及中值升高。17—OHCS 的相位在整个模拟失重期后移。皮质醇、17—OHCS 与钙变化存在相关性,提示糖皮质激素可能在短期失重引起的脱钙中起一定作用。     

模拟失重（悬吊—30°）对大白鼠肾上腺髓质儿茶酚胺昼夜节律的影响

利用头低位(-30°)悬吊大白鼠8天的实验,对320只大白鼠观察对照日、悬吊第2、3、8天肾腺髓质儿茶酚胺(CA)含量的昼夜节律特征。实验数据用最小二乘法—余弦法数学分析。结果表明,悬吊第2天肾上腺素(E)节律水平显著下降,去甲肾上腺素(NE)的最大相位角移到夜间;悬吊第3天E 和NE 的最大相位角都移到夜间;悬吊第8天E 和NE 的水平都显著升高,最大相位角仍在夜间出现。以上结果说明模拟失重显著地影响了正常的大白鼠肾上腺髓质CA 的昼夜节律。     

模拟失重对大鼠肺动脉反应性的影响及其机制研究

目的研究模拟失重对肺动脉反应性的影响及其机制。方法采用-30°尾悬吊14d大鼠失重模型模拟微重力生理效应,利用离体灌流技术测量对照组和尾悬吊14d组大鼠肺动脉环对苯肾上腺素(PE)、氯化钾(KCl)和乙酰胆碱(Ach)等血管活性物质的反应性及Nω-硝基-L-精氨酸甲酯(L-NAME)对肺动脉收缩反应的影响,免疫印迹分析两组肺动脉内皮型一氧化氮合酶(eNOS)的表达。结果与对照组相比,尾悬吊组对PE和KCl的收缩反应显著下降,对Ach的舒张反应明显增强;L-NAME处理后使尾悬吊组对PE的收缩反应恢复;尾悬吊组大鼠肺动脉组织eNOS表达显著高于对照组。结论模拟失重后肺动脉收缩反应下降,舒张反应增强,肺动脉内皮细胞eNOS表达增加以致舒张产物NO增加是肺动脉收缩反应性下降的主要原因。     

失重或模拟失重对基因表达的影响

综述了前人在失重或模拟失重与基因表达的关系方面的研究成果,从三个方面重点阐明了失重或模拟失重对呆区神经系统内基因表达的影响,从中可以看出,中枢神经系统的基因的表达是受重力因素精确调节的,在分子水平上研究问题微重力环境中枢神经系统的影响具有重要意义。     

次声对大鼠心率与血压影响的实验观察

目的:观察大鼠暴露于8Hz,130dB及90dB次声不同时间后血压及心率的变化。方法:将90只雄性大鼠随机为对照组、90dB暴露组及130dB组各5组(n=6),在1,7,14,21和28d暴露期间施以次声,2h/d,采用颈动脉插管法记录大鼠血压与心率。结果:与对照组比较,90dB1d组及130dB1d组大鼠心率均加快(P<0.01),7,14,21,28d组无显著变化(P>0.05);130dB1d组心率快于90dB1d组(P<0.05)。90dB及130dB的1,14,21,28d组左室收缩压增加(P<0.01),90dB7d组无显著变化,而130dB7d组较90dB7d组增加(P<0.05)。90dB及130dB的1,7,14d组大鼠左室舒张压无显著变化(P>0.05),而21,28d组增加(90dB组P<0.05;130dB组P<0.01),130dB组增加较90dB组快。结论:次声对大鼠血压及心率有一定影响,与次声作用时间和声压级水平有关。     

模拟失重条件下体温调节的特点

为观察模拟失重条件下体温调节的特点，５名健康男性－６°头低卧床７ｄ、对照３ｄ、恢复２ｄ。结果表明：卧床中体温保持了觉醒－睡眠的昼变化规律，但节律发生了一定改变，直肠温度昼夜节律的改变主要出现在卧床初期。头颈部皮肤温度明显升高，温度分布改变。     

模拟失重对大鼠后肢动脉血管床血管反应性的影响

目的 观察模拟失重对大鼠后肢血管床血管反应性的影响。方法 采用尾部悬吊大鼠模型模拟失重，利用离体后肢恒流灌流技术测定模拟失重２ｗｋ后动及血管床反应性的变化。     

模拟失重大鼠基底动脉血管壁超微结构的变化

目的为进一步阐明模拟失重下脑血管结构重塑变化的细节与性质。方法利用透射电镜技术观察了４周尾部悬吊大鼠基底动脉管壁超微结构的变化,并与对照组进行比较。结果在４周尾部悬吊大鼠基底动脉管壁可见以下几种形式的变化：①平滑肌细胞由收缩表型转化为合成表型。表现为：平滑肌细胞由梭形变为多角形或不规则形。细胞突起周围可见有较多的由其分泌的胶原蛋白或弹性蛋白。胞质内除肌丝外,可见有较多的粗面内质网、高尔基体和线粒体。细胞间质增厚、增多。②迁移。此现象在近内弹力层的平滑肌细胞多见。可见中膜平滑肌细胞伸出较长的突起,穿越过附近的平滑肌细胞及内弹力层而到达内皮下层,此处的内弹力层结构变得模糊;还可见内皮下层局部增厚、有大量松散的细胞间质,其内可见有体积较小、圆形的合成表型平滑肌细胞;可见原内弹力层变薄,而在内皮下形成新的内弹力层,那些迁移来的平滑肌细胞渐变为梭形,处于部分合成表型。③增生。中膜平滑肌细胞层数增加,由对照组的４～５层增加到５～６层。细胞排列较对照组不够整齐。结论４周尾部悬吊可导致大鼠基底动脉血管管壁发生增生改变,血管平滑肌细胞重新排列,部分细胞也由收缩表型向合成表型转变,并出现细胞迁移现象。     

模拟失重大鼠肺组织一氧化碳表达的变化

目的　研究在模拟失重大鼠肺组织中一氧化碳表达的变化 ,探讨其在失重时肺组织损伤中的作用。　方法　采用尾部悬吊模拟失重 ,分为悬吊 7d和 2 1d及相应对照 4组 ,每组 10只健康雄性 SD大鼠 ,共 4 0只大鼠。并采用原位杂交技术检测肺组织诱导型血红素氧合酶 (HO- 1) m RNA表达情况。　结果　同正常对照组相比 ,7d尾悬吊模拟失重大鼠肺组织 HO- 1m RNA表达水平明显增高 ,且具有统计学意义 (P<0 .0 1) ,2 1d悬吊组模拟失重大鼠肺组织 HO- 1m RNA表达水平仍显著增高 (P<0 .0 1)。　结论　在模拟失重条件下肺组织一氧化碳的表达水平增高。     

模拟失重大鼠不同部位动脉动脉血管壁超微结构的变化

目的 研究模拟失重下身体不同部位动脉血管壁结构重塑变化的性质及其可逆性。方法 用透射电镜观察尾部悬吊４ｗｋ（ＳＵＳ－４）、悬吊４ｗｋ后恢复１ｗｋ（ＲＥＣ－１）,及对照（ＣＯＮ）大鼠后肢和头颈部动脉血管壁的超微结构改变。结果 后肢的动脉血管（如股动脉及胫前动脉）的改变是：ＳＵＳ－４组平滑肌层数减少,平滑肌细胞内肌丝减少,间质胶原增多;ＲＥＣ－１组内弹力层增厚,平滑肌细胞内肌丝增加,内皮下出现合成表型     

昼夜节律在调控免疫系统功能中的作用

昼夜节律使机体生理、生化、行为等生命现象表现为以大致24 h为周期的振荡规律,受一系列生物钟基因(bmal1、clock、cry、per)和钟控基因(rev-erbα、rorα、dbp、tef、hlf等)调控.生物钟基因广泛存在于机体各免疫器官、组织和细胞中,使免疫细胞功能(迁移和趋化、吞噬、杀伤活性等)及多种免疫参数(循环免疫细胞及其亚群的相对和绝对数量、细胞因子水平等)呈现显著的昼夜节律性变化,从而在维持免疫稳态中发挥重要作用.此外,一些免疫相关疾病也与昼夜节律和生物钟系统异常密切相关.该文将着重阐述昼夜节律及生物钟系统对免疫细胞功能的影响及其在一些免疫相关疾病中的作用.     

Morning or evening training: effect on heart rate circadian rhythm

Abstract Twenty male endurance athletes (aged 20–25 years) carried out 2-hour daily training sessions, every day from Monday to Friday, for an overall period of 4 weeks. Four different weekly training time table (09.00-11.00; 11.00-13.00; 16.00-18.00; 18.00-20.00 hours) were followed, changing the time slot each week. Each athlete trained, in turn, in each period. The fifth day of each week, heart rate was monitored for 24-28 hours. Statistical analysis employed the single and mean cosinor methods. The heart rate (HR) circadian rhythm was statistically significant (p<0.05) in all 4 training session time. The HR acrophase is progressively postponed during the afternoon: the heart rate acrophase for training done between 18.00 and 20.00 is delayed by approximately 3 hours compared to that of the training done between 09.00 and 11.00. Training done at different daily times synchronizes the HR circadian rhythm. Temporal programming of physical activity is a tool capable of modifying the temporal structure of physiological variables. This approach can be of great interest for coaches who plan training programs and it may benefit athletes when time zone adjustment is an issue, such as transferring to a different continent for a competitive event.     

老年原发性高血压患者窦性心率震荡与血压晨峰的关系

目的探讨窦性心率震荡(HRT)与老年原发性高血压患者血压晨峰(MBPS)的关系。方法将68例老年原发性高血压患者根据24 h动态血压(ABPM)监测分为晨峰组和非晨峰组,所有受试者行24 h动态心电图(Holter)检查,计算机上读出HRT的参数:震荡初始值(TO)及震荡斜率值(TS),并分析两组的参数值。结果晨峰组TO明显高于非晨峰组,TS明显低于非晨峰组(P<0.05)。结论 HRT对老年原发性高血压及伴有血压晨峰患者的心源性损害有较好的预测作用。     

Radioprotective effect of endogenous melatonin secretion associated with the circadian rhythm in irradiated rats

Abstract

Purpose: We investigated the radioprotective effect of endogenous melatonin release at different times associated with the circadian rhythm on head and neck radiotherapy.

Materials and methods: Two groups of animals were subjected daily to 8?Gy single fraction radiotherapy in the head and neck region from 5:00 to 6:00 (the morning group) or from 19:00 to 20:00 (the evening group). Corresponding untreated groups served as controls. Submandibular glands from rats sacrificed on the seventh day after irradiation were assessed biochemically and histopathologically. Melatonin, malondialdehyde and superoxide dismutase levels in blood collected immediately prior to irradiation were measured with rat-specific ELISA kits.

Results: In irradiated rats, melatonin, malondialdehyde and superoxide dismutase levels were significantly higher in the evening group than in the morning group. In nonirradiated rats, melatonin and superoxide dismutase levels were significantly higher in the evening group than in the morning group. The areas of seromucous acinar cells were similar between the irradiated and nonirradiated evening groups, but the area was higher in the evening irradiated group than in the morning irradiated group.

Conclusion: Consideration of endogenous melatonin secretion associated with the circadian rhythm may offer new therapeutic solutions for the complications of head and neck radiotherapy.     

Associations of fitness and physical activity with orthostatic responses of heart rate and blood pressure at midlife

Cardiorespiratory fitness (CRF) and physical activity (PA) are associated with autonomic function, but their associations to orthostatic autonomic responses are unclear in epidemiological setting. We hypothesized that higher CRF and PA would associate with higher immediate vagal responses and lower incidence of adverse findings during orthostatic test. At age of 46, 787 men and 938 women without cardiorespiratory diseases and diabetes underwent an orthostatic test (3‐minutes sitting, 3‐minutes standing) with recording of RR intervals (RRi) and blood pressure (BP) by finger plethysmography. Acute responses of RRi (30:15 ratio) and BP were calculated. CRF was measured by a submaximal step test and daily amount of moderate‐to‐vigorous PA (MVPA) for 2 weeks by wrist‐worn accelerometer. Lifelong PA was based on questionnaires at ages of 14, 31, and 46. High CRF was significantly associated with higher RRi 30:15 ratio (adjusted standardized β = 0.17, P < 0.001) and milder acute decrease of systolic BP while standing (β = 0.10, P = 0.001), while MVPA was not (β = 0.04 for RRi 30:15 ratio and β = 0.05 for systolic BP acute response). High lifelong PA was significantly associated with higher RRi 30:15 ratio (β = 0.08, P = 0.002) but not with acute systolic BP response. Those in the lowest tertile of CRF had 9.2‐fold risk (P = 0.002) of having postural orthostatic tachycardia syndrome compared to more fit. Cardiorespiratory fitness and lifelong physical activity, but not current physical activity, were independently associated with higher cardiac vagal response to orthostasis. The present results underscore the importance fitness and lifelong physical activity in prevention of abnormal autonomic function and related cardiovascular risk.     

Isometric handgrip training lowers blood pressure and increases heart rate complexity in medicated hypertensive patients

Hypertension is characterized by elevated blood pressure (BP) and autonomic dysfunction, both thought to be improved with exercise training. Isometric handgrip (IHG) training may represent a beneficial, time‐effective exercise therapy. We investigated the effects of IHG training on BP and traditional and nonlinear measures of heart rate variability (HRV). Pre‐ and post‐measurements of BP and HRV were determined in 23 medicated hypertensive participants (mean ± SEM, 66 ± 2 years) following either 8 weeks of IHG training (n = 13) or control (n = 10). IHG exercise consisted of four unilateral 2‐min isometric contractions at 30% of maximal voluntary contraction, each separated by 4 min of rest. IHG training was performed 3 days/week for 8 weeks. IHG training decreased systolic BP (125 ± 3 mmHg to 120 ± 2 mmHg, P < 0.05) and mean BP (90 ± 2 mmHg to 87 ± 2 mmHg, P < 0.05), while sample entropy was increased (1.07 ± 0.1 to 1.35 ± 0.1, P < 0.05) and the fractal scaling distance score was decreased (0.34 ± 0.1 to 0.19 ± 0.1, P < 0.05). No significant changes were observed in traditional spectral or time‐domain measures of HRV or control participants. IHG training improves nonlinear HRV, but not traditional HRV, while reducing systolic and mean BP. These results may highlight the benefits of IHG training for patients with primary hypertension.     

模拟微重力对NIH-3T3细胞clock及bmal1基因表达的影响

目的探讨模拟微重力对NIH-3T3细胞节律基因clock与bmal1 mRNA表达的影响。方法 NIH-3T3细胞采用回转器分别回转培养6 h,12 h,18 h,24 h,30 h,36 h,42 h和48 h,同时设置1 G静置培养为对照组。Trizol试剂提取细胞总RNA,实时定量PCR法检测节律基因clock及bmal1 mRNA在各时间点的相对表达量。通过余弦法获取节律参数,并经振幅检验分析是否存在昼夜节律。结果 clock及bmal1基因mRNA的表达趋势相近。对照组clock与bmal1 mRNA相对水平呈现节律性表达,而回转组表达无节律性。回转组mRNA相对水平最大值出现于约6 h时间点,最小值出现在约18 h,而对照组分别出现于约18 h与24 h。与对照组比回转组的周期延长了约16 h。回转后clock与bmal1的峰值相位前移。结论 NIH-3T3细胞中clock与bmal1的表达存在同步化的转录特征。模拟微重力可影响clock与bmal1节律的周期长度及峰值相位。     

武警新战士运动应激时心率和血压的变化

 目的 检测新入伍战士运动应激时心率和血压的反应.方法 采用活动平板运动试验,按照标准的Bruce方案从第3级开始对85名新入伍战士进行试验,测量休息时、运动应激中每3 min和恢复阶段每2 min的心率和血压.结果 运动应激开始后心率较安静时成倍增加,此后心率随着运动应激量的增加而增快,极量心率约为安静时的2.5倍,增加117次/min,期间有两个高峰,分别为运动至第5级和第7级时.恢复期心率以停止运动后2 min内减慢明显(减慢36次/min),10 min后恢复正常;运动应激时血压升高,以收缩压升高为主,应激过程中收缩压和舒张压分别约增加21 mmHg和4 mmHg,12 min后恢复至安静时水平,运动应激后舒张压持续降低.结论 运动应激时心率和收缩压的变化呈双峰型,心率恢复较血压快.     

高压氧治疗对患者血压及心率变化的影响

目的 观察高压氧(HBO)治疗对人体血压、心率的影响,为临床更安全、有效地实施HBO治疗提供依据.方法 对行HBO治疗的57例患者(其中高血压病患者22例)分别于HBO治疗前、加压结束、稳压25 min、减压结束前、HBO治疗结束1 h测量血压及心率,并进行统计学分析.结果 高血压病患者及非高血压病患者血压、平均动脉压及心率的变化规律基本一致,收缩压在减压结束前与HBO治疗前比较明显升高(P<0.05);舒张压于稳压、减压阶段与HBO治疗前比较明显增高(P<0.05);平均动脉压于稳压、减压阶段与HBO治疗前比较明显升高(P<0.05);心率自加压结束前至减压结束前与HBO治疗前比较均明显减慢(P<0.01).结论 高血压病患者及非高血压病患者HBO治疗过程血压、平均动脉压及心率的变化规律基本一致.HBO治疗可以引起患者的血压升高、平均动脉压升高、心率减慢,且在减压阶段作用尤其明显,应引起足够的重视.