美托洛尔对缺氧-再给氧心肌细胞C-FOS表达和游离钙的影响

目的和方法研究表明,c-fos是细胞核内重要的原癌基因,它的表达产物对细胞具有重要意义,c-fos的表达产物Fos单独不能与DNA结合,Fos和Jun通过亮氨酸拉链形成二聚体,即具有活性的转录因子复合物AP.1,AP.1通过顺式作用激活相关的基因,从而调节基因的表达与蛋白质的合成。在正常情况下,c-fos在细胞中仅有低水平表达,但在心肌缺血再灌注中c-fos表达迅速增加。心肌细胞在缺氧-再给氧（A/R）时会产生大量氧自由基,氧自由基可诱导原癌基因表达,原癌基因表达程度与心肌细胞复氧损伤程度及细胞内游离钙有关。Ca²⁺超载可导致细胞不可逆损伤及细胞信息传递的紊乱,大量氧自由基生成及脂质过氧化物增强是心肌缺血再灌注损伤的主要机制之一。超氧化物岐化酶（SOD）作为重要的抗氧化酶可清除超氧阴离子自由基,保护心肌细胞,减轻心脏功能的损伤程度,其活性高低反映了机体清除氧自由基的能力。本研究通过培养心肌细胞,在细胞水平模拟心肌A/R损伤,用粘附式细胞仪,以荧光探针技术激光共聚焦扫描及免疫组化、灰度分析观察美托洛尔对培养心肌细胞A/R时细胞内钙(Ca²⁺)荧光强度、SOD活性及c-Fos表达的影响。结果心肌细胞A/R后,细胞内Ca²⁺荧光强度升高,对照组为:167.3±32.8,0.3±0.04,A/R组为:562±128.6,97.6±12.8,P<0.01。细胞培养液中SOD活性、平均灰度值降低,P<0.01。美托洛尔组上述改变得到明显改善,细胞内钙(Ca²⁺)荧光强度显著降低为376±39.1,22.8±8.2,细胞培养液中SOD活性、平均灰度值显著增高,P<0.05。^#P<0.01与对照组比较*P<0.05与A/R组比较。结论本实验证实美托洛尔能可明显减少c-fos的表达,提高心肌细胞SOD活性,有效清除超氧阴离子自由基,保护细胞膜结构完整性及阻止Ca²⁺内流,减轻Ca²⁺超载,对A/R心肌具有良好的保护作用。美托洛尔是选择性阻滞心脏β1受体,保护机制可能通过调节细胞膜腺苷酸环化酶活性,减少钙离子内流,从而降低心肌氧耗量,改善缺血再灌注损伤。     

硒对培养乳鼠心肌细胞缺氧—再给氧损伤影响的实验研究

硒与克山病发病率、冠心病死亡率呈负相关,临床上已用硒和vitE合剂治疗心绞痛。有人在整体心脏模型中证实了硒对缺血缺氧心脏具有保护作用。但无法排除全身体液、激素水平变化及心脏内各类型细胞的相互影响。本实验通过建立培养乳鼠心肌细胞缺氧—再给氧损伤模型,研究不同剂量的硒对心肌细胞缺氧—再给氧损伤的作用,这有利于临床硒的合理应用。     

镁对缺氧再给氧心肌保护作用的实验研究

实验研究心肌细胞缺氧－再给氧（ＡＯ－ＲＯ）时镁对细胞对脂质过氧化物（ＬＰＯ），Ｃａ＾２＋荧光强度及超微结构的影响，结果：心肌细胞ＡＯ－ＲＯ后，细胞线粒体肿胀，变性及排列紊乱，结果受损、细胞内ＬＰＯ、Ｃａ＾２＋荧光强度升高，低镁０．３ｍｍｏｌ／Ｌ＋ＡＯ－ＲＯ组比单纯ＡＯ－ＲＯ组再明显，Ｐ〈０．０１，镁２．０ｍｍｏｌ／Ｌ和０．８ｍｍｏｌ／Ｌ组，上述改变得到明显改善，这与镁具有抗ＬＰＯ保护细胞膜结构完整性及阻止Ｃａ＾２＋内流，减轻Ｃａ＾２＋超载从而降低心肌Ａ０－ＲＯ损伤等作用有关。     

腺苷A1受体激动剂对心肌细胞缺氧再给氧脂质过氧化损伤的保护作用

目的观察腺苷A1受体激动剂对培养的心肌细胞缺氧再给氧脂质过氧化损伤的影响。方法以培养的心肌细胞为模型,在缺氧再给氧损伤细胞后,给予腺苷A1受体激动剂R(-)N6-(2-phenylisopropyl)adenosine(R-PIA)(0.1及1μmol/L),测定培养液上清液中超氧化物歧化酶(SOD)的活性和乳酸脱氢酶(LDH)、丙二醛(MDA)的含量及细胞MTT代谢率的变化。结果腺苷A1受体激动剂可以使培养液上清液中LDH和MDA的含量明显降低,SOD的活性增强,细胞MTT代谢率明显升高,且呈现剂量依赖性。而且这种作用可被腺苷A1受体拮抗剂8-cyclopentyl-1,3-dipropylxanthine(CPDPX)所拮抗。结论腺苷A1受体激动剂对缺氧再给氧损伤培养的心肌细胞有保护作用。     

牛磺酸对心肌细胞缺氧—再给氧损伤的保护作用

在心肌细胞缺氧－再给氧模型上，发现缺氧及再给氧后细胞膜荧光偏振度明显增加；线粒体，肌原纤维等结构受损；细胞内脂质过氧化物荧乐强度及荧光比率升高，上述变化再给氧组均比缺氧组更明显。     

卡托普利晚期预处理对缺氧复氧心肌细胞游离钙的影响

目的观察卡托普利晚期预处理对缺氧复氧心肌细胞游离钙的影响,评价其延迟心肌的保护作用。方法建立培养乳鼠心肌细胞缺氧复氧损伤模型。设正常对照组、缺氧复氧组、缺氧预适应组、卡托普利预处理组、蛋白激酶C阻断剂+卡托普利组、一氧化氮合酶阻断剂+卡托普利组和核因子κB阻断剂+卡托普利组。利用分光光度计测定丙二醛和超氧化物岐化酶含量;全自动生物化学分析仪测定乳酸脱氢酶含量。Flou3AM负载染色和流式细胞分析技术测定细胞内钙离子浓度。结果卡托普利预处理和缺氧预处理均可减轻缺氧再灌注时心肌细胞内钙离子浓度增加(594±5nmolL、507±32nmolL比789±9nmolL,P<0.01),抑制乳酸脱氢酶和丙二醛的增加和超氧化物岐化酶含量的降低;但与对照组(414±37nmolL)比较钙内流仍有轻度增加(P<0.05);预先分别加入蛋白激酶C阻断剂、一氧化氮合酶阻断剂、核因子κB阻断剂与卡托普利共同孵育细胞,行缺氧复氧损伤所测得细胞内钙离子浓度分别为676±32nmolL、700±37nmolL和689±11nmolL,与卡托普利预处理组比较有所增加(P<0.05);但与缺氧复氧组比较仍有降低(P<0.05)。结论以上提示,卡托普利预处理可抑制缺氧复氧时的钙超载及其脂质过氧化损伤。其机制可能是通过轻度增加钙内流、启动心肌延迟保护作用;其过程可能涉及蛋白激酶C、一氧化氮合酶和核因子κB信号转导通路中的多个环节。     

超氧阴离子自由基对心肌细胞的损伤作用

目的 :探讨超氧阴离子自由基 (O2 ·- )对培养心肌细胞的影响。方法 :利用黄嘌呤氧化酶 /黄嘌呤(XO/X)产生O2 ·- 系统作用于原代培养的新生大鼠心肌细胞 ,观察其对心肌细胞的损伤 ,并分析其对核DNA、Na/K ATP酶 (ATPase)活性和脂质过氧化的影响。结果 :O2 ·- 使心肌细胞受损 ,扫描电镜见细胞伪足变短甚或消失并趋于固缩 ,乳酸脱氢酶漏出增多〔(2 0 2 .0 0± 19.5 0 )U/L〕 ,核DNA单链断裂增加 (DNA EB的相对荧光强度 :31.93± 3.4 7) ,ATPase活性下降 [4 .75± 0 .4 3(μmol/min) a],丙二醛含量增加〔(1.16± 0 .14 )nmol/L〕 ,过氧化氢酶 (CAT)能明显抑制这些损伤效应。结论 :O2 ·- 可对心肌细胞及其核酸、蛋白质和脂质造成损伤。     

牛磺酸对心肌细胞缺氧－再给氧损伤的保护作用

在心肌细胞缺氧－再给氧模型上，发现缺氧及再给氧后细胞膜荧光偏振度明显增加；线粒体、肌原纤维等结构受损；细胞内脂质过氧化物（ＬＰＯ）荧光强度及［Ｃａ２＋］ｉ荧光比率升高，上述变化再给氧组均比缺氧组更明显。牛磺酸能剂量依赖性地降低细胞膜荧光偏振度，提高细胞膜脂质流动性；改善细胞的超微结构；可能与其明显降低细胞内ＬＰＯ荧光强度及［Ｃａ２＋］ｉ荧光比率有关。     

异丙酚对乳鼠心肌细胞缺氧/复氧损伤后凋亡的影响

目的探讨异丙酚对乳鼠心肌细胞缺氧/复氧损伤后凋亡的影响及其作用机制。方法把培养的18孔乳鼠心肌细胞随机分成3组:对照组、单纯缺氧/复氧组、异丙酚处理组。培养3 d的乳鼠心肌细胞给予1 h缺氧和3 h复氧处理（单纯缺氧/复氧组）。复氧期间给予异丙酚（25μmol/L）处理（异丙酚处理组）,复氧结束后采用DNA原位末端缺口标记技术（TUNEL）测定心肌细胞凋亡比例同时用免疫组化法测定心肌细胞内抗凋亡分子Akt、Bcl-2和促凋亡分子p38 MAPK的表达。结果与对照组相比,异丙酚显著降低了缺氧/复氧诱导的心肌凋亡（10.1%±3.2%vs25.3%±6.2%,P<0.01）,并改变了缺氧/复氧过程中凋亡介导因子的活性。免疫组化的结果显示,异丙酚增加了心肌细胞内抗凋亡蛋白pAkt和Bcl-2的形成,降低了促凋亡蛋白p38的活性。结论异丙酚对培养心肌细胞缺氧损伤后的凋亡有显著的保护作用,该作用与其对pAkt、Bcl-2和p38的影响密切相关。     

缺血再灌注对心肌细胞CX43表达的影响

目的检测缝隙连接通道蛋白43（Conexin43，CX43）在缺血再灌注中的心肌细胞基因表达和CX43通道蛋白变化情况，分析CX43变化的原因，判断CX43在心肌缺血再灌注中所起得作用。方法原代培养心肌细胞，建立缺血再灌注模型，分别于正常、缺氧30min、再灌注1h、2h、3h、6h搜集细胞。逆转录聚合酶链式反应（RT-PCR）检测CX43mRNA表达、蛋白免役印迹法（Westernblot）检测CX43蛋白的含量。结果未用药干预的心肌细胞缺氧30min时CX43mRNA表达与蛋白含量和正常相比无显著差异（P〉0．05），再供氧1h、2h、3h．6h则分别减少了39．16％、45．00％、46．67％、51．67％。和正常相比差异显著（P〈0．01）。其中再供氧1h下降幅度最大。结论CX43在心肌细胞缺氧再灌注过程中mRNA表达与蛋白含量均是减低的，其中再供氧1h下降幅度最大。     

Two monitoring methods of oral anticoagulant therapy in patients with mechanical heart valve prothesis: a meta-analysis

Oral anticoagulant therapy (OAT) with warfarin has become the standard therapy for the patients with mechanical heart valve prothesis. The monitoring method of self-monitoring or self-management was promising to optimize the use of warfarin, but most of previous studies have included patients with various indications of OAT, which made it difficult to extrapolate the results to the specific patient population with mechanical heart valve prostheses. This study was intended to evaluate the new and traditional monitoring methods in patients with mechanical heart valve prostheses. Relevant literature finished before Dec. 2010 were searched through a number of digital databases. And then they were pooled by RevMan 4.2 and R 2.13.0 in three fields: rate within the target range, test frequency and occurrence rate of poor events. Five randomized control trials with a total of 2,219 patients were identified. Pooled estimates showed reductions in thromboembolic events (OR 0.52, 95% CI 0.35–0.77; P = 0.0012) and all-cause mortality (OR 0.50, 95% CI 0.29–0.86; P = 0.0115). No difference was noted in major and minor haemorrhage. All trials reported improvements in the mean proportion of international normalized ratios in range. Self-monitoring and self-management can improve the quality of OAT in the patients with mechanical heart valve prostheses. The patients spend more time within the therapeutic range resulting in decreases in thromboembolic events and mortality, with no increase in haemorrhage. However, self-monitoring and self-management was not feasible for all patients, and require identification and education of suitable candidates. The success of self-monitoring and self-management method depends on consistent, regular, and frequent testing.     

Low-dose oral anticoagulation in patients with mechanical heart valve prostheses: final report from the early self-management anticoagulation trial II.

AIMS: In mechanical heart valve recipients, low-dose international normalized ratio (INR) self-management of oral anticoagulants can reduce the risk of developing thrombo-embolic events and improve long-term survival compared with INR control by a general practitioner. Here, we present data on the safety of low-dose INR self-management. METHODS AND RESULTS: In a prospective, randomized multi-centre trial, 1346 patients with a target INR range of 2.5-4.5 and 1327 patients with a target INR range of 1.8-2.8 for aortic valve recipients and an INR range of 2.5-3.5 for mitral or double valve recipients were followed up for 24 months. The incidence of thrombo-embolic events that required hospital admission was 0.37 and 0.19% per patient year in the conventional and low-dose groups, respectively (P = 0.79). No thrombo-embolic events occurred in the subgroups of patients with mitral or double valve replacement. The incidence of bleeding events that required hospital admission was 1.52 and 1.42%, respectively (P = 0.69). In the majority of patients with bleeding events, INR values were < 3.0. Mortality rate did not differ between the study groups. CONCLUSION: Data demonstrate that low-dose INR self-management does not increase the risk of thrombo-embolic events compared with conventional dose INR self-management. Even in patients with low INR target range, the risk of bleeding events is still higher than the risk of thrombo-embolism.     

Maternal and fetal sequelae of anticoagulation during pregnancy in patients with mechanical heart valve prostheses

Previous reports indicate an increased risk of thrombotic and embolic events in patients with mechanical heart valve prostheses during pregnancy. We prospectively followed 50 pregnancies in 49 patients with 62 cardiac prostheses from presentation at the antenatal clinic through the remainder of the pregnancy. Of the 60 mechanical prostheses, 39 were Medtronic-Hall, 7 St. Jude Medical, 7 Starr-Edwards and 7 Bj?rk-Shiley. Forty-three patients were in New York Heart Association functional class I or II and 6 were in functional class III or IV. Forty-five patients were in sinus rhythm and 4 had chronic atrial fibrillation. All patients received warfarin during the first and second trimesters. Forty-one pregnancies proceeded beyond 28 weeks. In 23 of these (group I) warfarin was replaced with heparin at 36 weeks gestation. In the remaining 18 (group II) warfarin was not substituted owing to premature onset of labor. The target prothrombin ratio (international normalized ratio) in patients receiving warfarin was 2.0 to 2.5. The partial thromboplastin time was maintained at 1.5 to 2.5 times the control value in patients receiving heparin. Eleven patients received dipyridamole plus warfarin for the duration of pregnancy. There were no maternal thromboembolic complications or deaths associated with pregnancy. Antepartum hemorrhage occurred in 1 patient at 35 weeks gestation. One patient (group I) experienced peripartum hemorrhage. All patients were hemodynamically stable before delivery, but 2 developed pulmonary edema during labor. The mean fetal birth weight was low (2.54 +/- 0.98 kg). There were 9 abortions (18%), 7 stillbirths (14%), 2 neonatal deaths (4%) and 2 instances of warfarin embryopathy (4%).(ABSTRACT TRUNCATED AT 250 WORDS)     

人工机械瓣膜置换术后口服抗凝药的抗凝治疗强度标准

目的 探讨适合我国人工机械瓣膜置换患者特点的抗凝强度标准并分别确定主动脉瓣置换(AVR)、二尖瓣置换(MVR)、双瓣置换(DVR)的抗凝强度标准。方法 对北京安贞医院心外科1658例人工机械瓣膜置换术后的患者随访,分析随访抗凝强度(国际标准化比,INR)与口服抗凝治疗相关并发症的关系,总结并发症发生率最低的抗凝强度范围,即最佳抗凝强度标准。结果 完成随访1508例,随访率91.0％,随访(0.08～5.08)年,平均随访(3.8±1.3)年,随访总人年数为5731.9。随访INR 2.13±0.56,口服华法林剂量(3.09±0.85)mg,发生血栓栓塞66例(1.17％人年),抗凝有关的出血115例(2.02％人年),总事件发生率为3.24％人年,其中INR于1.3-2.3(AVR:1.3～1.8;MVR及DVR:1.8～2.3)范围内出血和总事件发生率最低(P<0.001)。结论 我国人工机械瓣膜置换患者的抗凝强度控制在INR1.3～2.3范围(AVR:1.3～1.8;MVR、DVR:1.8～2.3),可以减少口服抗凝治疗的并发症,获得满意的预防血栓栓塞,减少与抗凝有关的出血的效果。     

Anticoagulation in pregnant women with mechanical heart valve prostheses

OBJECTIVE: To evaluate the outcome of pregnancy in women with mechanical heart valve prostheses in relation to the anticoagulant treatment used in the first trimester and the incidence of thrombotic and bleeding complications. METHODS: 92 pregnancies in 59 women were followed between 1986 and 1997. In 31 pregnancies, oral anticoagulants were discontinued when pregnancy was diagnosed and subcutaneous heparin was started (12 500 U every 12 hours) adjusted to prolong the adjusted partial thromboplastin time to twice the control level. In the second trimester oral anticoagulants were resumed but changed to heparin again 15 days before the expected delivery date. In 61 pregnancies oral anticoagulants were continued during the first trimester. The same regimen of heparin was used for delivery. RESULTS: Abortion or fetal losses were similar (p = 0. 5717) in women exposed to oral anticoagulants in the first trimester (13/61; 25%) compared with those who received adjusted subcutaneous heparin (6/31; 19%). Embolic episodes were more common (p = 0.0029) in women who received heparin (4.92%) compared with those on oral anticoagulants (0.33%). Embolic episodes were cerebral and transient. No valve thromboses were observed. No malformations appeared in the 71 newborns, except for one case of hydrocephalus. There were no maternal deaths secondary to thrombotic complications. The only death was the result of major bleeding after the delivery of a premature stillborn. CONCLUSIONS: Oral anticoagulants seem to be safer for the mother than adjusted subcutaneous heparin. Heparin does not offer a clear advantage over oral anticoagulation in the pregnancy outcome.