糖尿病大鼠心肌病理变化及脂质过氧化和一氧化氮的改变

目的：研究糖尿病心肌的病理变化及其发生机制。方法：用光镜及透射电镜观察四氧嘧啶诱导的糖尿病1个月大鼠心肌形学改变,并测定心肌细胞超氧化物歧化酶（SOD）、谷膛甘肽过氧化物酶（GSH－Px)、一氧化氮合酶（NOS）的活性及一氧化氮（NO）、丙二醛（MDA）含量。结果：光镜下见心肌细胞萎缩、嗜酸性变及空泡变性,间质纤维增生,透射电镜下见线粒体扩张、嵴变短,内质网扩张,骨原纤维破坏,间质胶原纤维增生。SOD、GSH－Px活性下降,NOS活性及NO、MDA含量增加。结论：糖尿病大鼠心肌病变主要为心肌萎缩、线粒体扩张及肌原纤维破坏,间质纤维增生,脂质过氧化作用及NO所致的损伤可参与其中。     

发光法测量自由基、脂质过氧化及抗氧化剂

生物和化学发光分析技术应用于基础医学研究和临床生化指标检测已日益受到重视,并以蓬勃之势在许多领域,如自由基医学及生物学、药理学、免疫学、生物化学深入发展。本刊特邀国内造诣深厚的有关专家介绍这些方面的基本概貌、研究进展和前景预测,旨在促进该分析技术在全国的广泛开展。在分子生物学研究方面,该技术虽亦崭露头角,但因我国起步较晚,这次未能组织综合介绍,希广大同仁在这方面努力工作,积累经验,为进一步交流提供基础。     

大鼠烧伤后血清过氧化脂质含量的变化

用80℃水烫伤大鼠腰部以下身体30秒(占体表面积35—40%)引起烧伤休克。在烧伤后不同时间取血测定血中脂质过氧化物的二级产物丙二醛的含量。烧伤后1、2小时的血中脂质过氧化物含量已开始上升,3.5小时明显增高,5小时达高峰,7小时开始下降,但仍明显高于正常。在高峰出现前(烧伤后4.5小时)开始用平衡克氏液腹腔透析治疗,透析1.5小时可以使增多的血清脂质过氧化物恢复到接近正常。血中脂质过氧化物出现的时间经过与动物烧伤休克的发展过程基本一致,提示自由基使脂质过氧化带来组织损伤可能参与烧伤休克的发生。腹腔透析的疗效进一步阐明该疗法治疗烧伤休克的原理。     

脂质过氧化对人内皮细胞的损伤及抗氧化剂的保护作用

以氢过氧化估烯作为培养人内皮细胞脂质过氧化反应的引发剂，以亚硒酸钠、维生素E、超氧化物歧化酶作为抗氧剂，应用光镜、脂质过氧化物测定及放射免疫分析等方法观察了抗氧剂对脂质过氧化损伤的内皮细胞形态结构和功能的保护作用。结果表明：氢过氧化枯烯激发和促进了内皮细胞的脂质过氧化反应；而硒、维生素E、超氧化物歧化酶使细胞脂质过氧化物含量减少，由过氧化作用造成的细胞收缩、生物膜系统的损伤程度减轻，对细胞前列腺素（PGI2）合成的抑制作用减弱。提示：上述抗氧剂可能通过对内皮细胞的保护作用，阻止动脉粥样硬化病变的形成和发展。     

丹参对急性心肌缺血时脂质过氧化的影响

本实验以结扎家兔冠脉左室支造成在体急性心肌缺血模型,以硫代巴比妥酸荧光法测定心肌组织脂质过氧化物含量,探讨心肌脂质过氧化情况及其与心电图ST段改变的关系,并以丹参注射液为心肌保护因素,观察脂质过氧化物、心电图ST段的变化,探讨丹参对心肌的保护作用。实验结果表明:结扎冠脉左室支40分钟时,缺血区心肌脂质过氧化物含量比对照组增加2.4倍(P<0.01),缺血区脂质过氧化物含量与心电图ST段抬高程度呈正相关(r=0.822,P<0.025)。预先静脉注射丹参注射液,使缺血区心肌脂质过氧化物含量较缺血组缺血区降低47.9%(P<0.02).并使冠脉左室支结扎后2至5分钟的心电图ST段抬高程度降低44.8～47.0%(P<0.05)。     

海水浸泡对火器伤兔肢体骨骼肌组织脂质过氧化反应影响的研究

目的:观察海水浸泡对火器伤伤口组织脂质过氧化反应的影响。方法:以滑膛枪发射质量250mg钢珠,致伤兔后肢,伤后将致伤兔随机分为两组:一组为海水浸泡组(SIG),将致伤兔浸泡于粗制海盐配制的人造海水中30min;另一组为单纯致伤组(SWG),伤后不浸泡海水。伤后3、6、12、24h手术取距伤道边缘0.5cm(A区)、1.5cm(B区)和2.5cm(C区)处肌组织,测定ATP、丙二醛(MDA)含量和超氧化物歧化酶(SOD)活力。取伤前骨骼肌组织作为对照。结果:伤后SIG兔伤肢骨骼肌MDA含量明显高于对照,伤后3、6h升高,12h略降,24h有再次升高的趋势。SWG的MDA含量变化与SIG相似,但升幅低于SIG;2组SOD活力和ATP含量的改变与MDA含量变化相似。结论:海水浸泡的火器伤伤口脂质过氧化反应增强,从而加重了肢体火器伤的过氧化反应。     

妊高征患者血中黄嘌呤氧化酶和过氧化脂质水平的变化

目的：探讨妊高征患者血清黄嘌呤氧化酶（XOD）与过氧化脂质（LPO）水平的变化。方法：采用比色法测定30例妊高征患者及20例正常孕妇血清XOD与LPO水平。结果：妊高征患者血清XOD、LPO水平显著高于正常妊娠妇女；妊高征患者血清XOD与LPO水平呈显著正相关，XOD水平与平均动脉压呈显著正相关。结论：胎盘缺血缺氧、过氧化反应增高是妊高征发病的主要环节。     

输精管结扎与实验性高血脂对听觉脑干电位及血清过氧化脂质的影响

输精管结扎12月以上日本大耳白兔16只,随机分为输精管结扎基础饲料(V-S)组和输精管结扎胆固醇(V-Ch)组。体重相近的同种雄兔16只,分为对照基础饲料(C-S)和对照胆固醇(C-Ch)组。听觉脑干电位检测结果表明:气导ABR阈值,输精管结扎组(V-S.V-Ch)与各门对照组比较无差异(P<0.05),而高胆固醇饲料组(C-Ch.V-Ch)则显著地高于对照组(P<0.01),并且与TC水平正相关(P<0.01);各组Ⅰ、Ⅲ、Ⅴ波潜伏期无延长,波间期各组比较也无显著差异,(P>0.05)。血清过氧化脂质含量与TC水平正相关(P<0.01)而与血清抗精子抗体滴度无相关(P>0.05)。本实验证明,实验性高血脂使气导ABR阈值及血清过氧化脂质增高,而输精管结扎对其无影响。     

自由基诱发剂对大肠癌细胞脂质过氧化、膜脂流动性及DNA含量的影响

本文以体外培养的大肠癌细胞为模型，观察了自由基诱发剂ｔｂｏｏＨ及抗癌药物对癌细胞脂质过氧化、膜脂流动性及ＤＮＡ含量的影响。结果表明，作用早期ＬＰＯ含量即有明显增加，且随温育时间的延长而增强，但早期ＤＮＡ含量则无明显变化，提示细胞ＬＰＯ含量的变化出现于细胞核酸ＤＮＡ改变之前。ｔｂｏｏＨ结合５－ＦＵ作用于癌细胞，发现在早期ＤＮＡ便可出现抑制作用，提示细胞膜的脂质过氧化损伤可增强抗癌药物的作用。采用ＤＰＨ荧光探针标记观察了细胞脂质过氧化与膜脂流动性的关系，结果表明ｔｂｏｏＨ和５－ＦＵ均能不同程度地引起大肠癌细胞膜脂流动性的减少。且这一效果可因抗癌药５－ＦＵ并用ｔｂｏｏＨ而明显增强，提示细胞膜膜脂流动性的改变是脂质过氧化介导癌细胞功能障碍的重要机制。     

输精管结扎对实验性动脉粥样硬化的影响

输精管结扎术后7和9个月家兔各10只,随机分为输精管结扎基础饲料(V-S)组和输精管结扎胆固醇(V-Ch)组,同种雄兔20只随机分为对照基础饲料(C-S)组和对照胆固醇(C-Ch)组。实验结果表明,V-S组血脂、脂质过氧化物含量与C-S组比较无差异,主动脉和冠动脉均无脂质斑块形成。在持续高脂负荷后,V-Ch组总脂、β-脂蛋白水平显著地高于C-Ch组,但是主动脉、冠动脉的病变面积和程度则无差异。这可能与V-Ch组血清脂质过氧化物含量与C-Ch组比较无增高有关,也可能与V-Ch组虽有抗精子抗体产生,但无循环免疫复合物形成有关。     

心脉灵对内毒素血症大鼠肺血管通透性及肺组织脂质过氧化物的影响

心脉灵以中医四逆汤为基础经剂型变化而得，具有回阳救逆之功效。以往的实验提示心脉灵有良好的抗内毒素休克作用。本实验用异硫氰酸荧光素右旋糖酐，分子量４０，０００（ＦＤ－４０Ｓ）观察发现：内毒素血症大鼠在给内毒素（ＥＴ）ｉ．ｖ后，１、３ｈ血浆荧光素下降率比对照组明显增加，支气管肺泡灌洗液（ＢＡＬ）中荧光素增长率相应地明显升高，同时发现血浆及肺组织脂质过氧化物也显著增高。事先给予心脉灵（ＸＭＬ），血浆荧光素下降曲线明显抬高，ＢＡＬ中荧光素上升曲线显著下移，血浆及肺组织脂质过氧化物也明显降低。提示内毒素血症大鼠肺血管通透性增加与脂质过氧化的增加有密切的关系，而心脉灵可能抑制肺脂质过氧化物的产生，从而改善了肺血管通透性。     

高浓度氧对沙土鼠脑缺血再灌流后脂质过氧化作用的影响

沙土鼠双侧颈总动脉结扎1小时后,于高氧环境中再灌流2小时,脑MDA含量(4.39±0.26nmol/mg蛋白)与空气对照组(2.63±0.50nmol/mg蛋白)、高氧对照组(3.07±0.52nmol/mg蛋白)、缺血组(2.96±0.41nmol/mg蛋白)及空气中再灌流组(2.79±0.59nmol/mg蛋白)相比较,差异均具有高度显著性(P<0.01)。大脑皮层TXB_2含量增加,6-Keto-PGF_(1α)含量减少,水、钠含量明显增加。但上述各指标与缺血后在大气环境中再灌流组相比,差异均无显著性。作者推测,高浓度氧导致脂质过氧化作用增强的机理可能源于异常的线粒体电子传递链功能。     

A review of high frequency oscillation ventilation in the neonate

In this study the use of high frequency oscillation (HFO) to treat neonates with respiratory failure is analysed. The theories behind gas exchange during HFO are reviewed and its specific application to neonatal care discussed. The mechanical performance of three HFO ventilators currently in use is compared with the views of medical staff operating them on a regular basis. The complex interactions between initial ventilator settings have led to difficulties in accurately comparing performance characteristics and ventilation strategies; each ventilator is seen to have its own strengths and weaknesses that contribute to the ventilator selection made. These interactions together with the specific HFO modes available on each ventilator should be taken into account when using a HFO for the first time or when switching from an alternative ventilation method. Medical staff who care for neonates suggest staff education and training into the variations of HFO will greatly improve its use in neonatal medicine.     

Effects of the ventilation pattern and pulmonary blood flow on lung heat transfer

To investigate the relative role of pulmonary perfusion compared to ventilation on lung heat exchange, we determined the effects of blood flow, tidal volume and frequency of ventilation on the rate of lung heat transfer. In anesthetized dogs and isolated, perfused lungs, we investigated the dependence of the overall lung heat transfer coefficient (HTC) and lung thermal capacitance upon ventilation and pulmonary blood flow. The relationship between the HTC and pulmonary blood flow was strongly dependent on ventilation parameters. A distributed model of non-steady-state heat exchange adequately described these observations and demonstrated that changes in pulmonary blood flow may be considered as changes in the effective conductivity of the bronchial walls as 0.4 (0.1) J s^–1m^–1 K^–1 per (l/min^–1) of pulmonary blood flow. Our model describes the complex relationship between HTC, ventilation pattern, and effective thermal conductivity of the bronchial walls, all of which present limitations for the use of lung heat transfer to determine pulmonary blood flow.     

三七总皂甙对急性缺氧时脑损伤及血中有关生化指标影响的探讨

本文观察了三七总皂甙对急性缺氧动物脑皮质与软脑膜微循环的保护作用,结果表明:三七总皂甙能抑制缺氧家兔第20分钟时PaO_2(缺氧组27.15±5.67,三七组39.63±6.38,P<0.01)和pH(7.21±0.04,7.30±0.03,P<0.05)的下降,并能减轻此时软脑膜微静脉的扩张(137.80±9.59,118.88±10.09,P<0.01),延长血流加速期(26.40±6.17,35.37±6.79,P<0.01)和脑血流停止时间(30.00±6.20.40.46±6.50),P<0.01)。电镜观察:三七总皂甙能减轻脑皮质细胞的损伤。血液生化指标测定:三七总皂甙具有抗低含缺氧5小时大鼠血清LPO(缺氧组4.04±0.38,三七组3.71±0.29,P<0.05)β—G活力(34.57±5.80,27.66±3.43,P<0.01)和血乳酸上升的作用。如上所述,三七总皂甙具有抗氧化、稳定溶酶体膜、改善机体能量代谢与软脑膜的微循环,因之对缺氧时脑皮质的损伤有保护作用。     

高频振荡通气治疗新生儿呼吸衰竭的对比性研究

目的探讨高频震荡通气对新生儿重症呼吸衰竭治疗的疗效。方法对比分析36例新生儿重症呼吸衰竭使用传统机械通气失败后改用高频震荡通气治疗前后动脉血氧分压（PaO2）,二氧化碳分压（PCO2）,血氧饱和度（SaO2）,动脉血氧分压与吸入氧浓度之比（PaO2/FiO2）,动脉-肺泡氧张力比值（a/APaO2）,氧合指数（oxygenation index,OI）。结果改高频通气治疗后二氧化碳分压（PaCO2）、氧合指数（OI）下降,（P〈0.01）。动脉血氧分压（PaO2）、动脉血氧分压与吸入氧浓度之比（PaO2/FiO2）、动脉-肺泡氧张力比值（a/APaO2）上升,（P〈0.01）。结论高频震荡通气能更好地改善重症呼吸衰竭新生儿的通气和气体交换,减少气压伤,对治疗新生儿重症呼吸衰竭具有较好的疗效。     

The effect of ventilation on spectral analysis of heart rate and blood pressure variability during exercise

Heart rate variability (HRV) and systolic blood pressure variability (BPV) during incremental exercise at 50, 75, and 100% of previously determined ventilatory threshold (VT) were compared to that of resting controlled breathing (CB) in 12 healthy subjects. CB was matched with exercise-associated respiratory rate, tidal volume, and end-tidal CO(2) for all stages of exercise. Power in the low frequency (LF, 0.04-0.15 Hz) and high frequency (HF, >0.15-0.4 Hz) for HRV and BPV were calculated, using time-frequency domain analysis, from beat-to-beat ECG and non-invasive radial artery blood pressure, respectively. During CB absolute and normalized power in the LF and HF of HRV and BPV were not significantly changed from baseline to maximal breathing. Conversely, during exercise HRV, LF and HF power significantly decreased from baseline to 100% VT while BPV, LF and HF power significantly increased for the same period. These findings suggest that the increases in ventilation associated with incremental exercise do not significantly affect spectral analysis of cardiovascular autonomic modulation in healthy subjects.     

The effects of exercise duration on dynamics of respiratory gas exchange,ventilation, and heart rate

This study investigated the effect of exercise duration on the response dynamics of oxygen consumptionVO₂, carbon dioxide outputVCO₂, ventilation V_E), and cardiac frequency (f _c) following stepped changes in exercise intensity, by manipulating the duration of the pretransition exercise period. A group of 11 healthy men performed a stepped exercise intensity cycling protocol on three separate occasions, each consisting of a stepped increase from 55% to 65% peak oxygen consumptionVO_2,peak of 6-min duration, followed by a stepped decrease to 55%VO_2,peak of 10-min duration. This stepped protocol was preceded by either 5, 15, or 60 min of cycling at 55%VO_2,peak. The response times for each variable were calculated at 10% increments between the prestep baselines and poststep plateaux. Following the stepped increase, the response times forVO₂ at the 50%, 60%, 70%, 80%, and 90% relative increments were significantly reduced in the 60-min condition compared to the 15-min condition (P< 0.05); however, the response times forVCO₂ andf _c were not significantly altered across the three conditions. No significant differences were found in the response times forVO₂,VCO₂ andf _c, across the three conditions following the stepped decrease in exercise intensity. It was concluded that the faster response time of aerobic metabolism to a stepped increase in exercise intensity was mediated by increases in active muscle temperature, leading to improved oxygen utilisation.