兔心肌挫伤心功能障碍与心肌细胞内Ca2+和线粒体ATP酶的变化

目的：探讨心肌细胞内游离钙([Ca^2 ]i)和心肌ATP酶变化在心肌挫伤（MC）后心功能障碍发生机制中的意义。方法：随机选取兔36只，分为6组：正常对照、伤后2、4、8、12、24h，每组6只。经右颈总动脉插管至左心室测左室压力。采用BIM-II型生物撞击机致成MC模型。在上述时相点测定左室压力，并测定心肌细胞内[Ca^2 ]i和心肌匀浆组织及线粒体ATP酶活力。结果：心脏收缩/舒张功能受到损害，心肌细胞内[Ca^2 ]i升高，心肌匀浆组织及线粒体ATP酶下降，相关分析表明心功能障碍与心肌细胞内[Ca^2 ]i含量升高呈明显负相关，与ATP酶活性降低呈明显正相关。结论：MC后心脏功能下降，心肌细胞内[Ca^2 ]i含量升高和ATP酶活性下降可能是其原因之一。     

黄芪对SHR心肌SERCA表达及血管平滑肌钙离子水平影响的初步探讨

目的:探讨黄芪注射液对SHR心肌SERCA的表达及血管平滑肌钙离子含量的影响.方法:将19只自发性高血压大鼠(SHR)与16只Wistar-kyoto大鼠(WKY)随机各分为空白对照组、低黄芪剂量组、中黄芪剂量组、高黄芪剂量组四组,分别每天腹腔注射0.9ml生理盐水和0.9ml、1.2ml、1.8ml的黄芪注射液共8周,再测量大鼠心肌中SERCA的表达和血管平滑肌钙离子含量.结果:SHR生理盐水组心肌SERCA在蛋白水平的表达,较WKY生理盐水组明是下降;SHR大剂量黄芪组心肌SERCA在蛋白水平的表达,较SHR生理盐水组明显升高.SHR生理盐水组血管平滑肌钙离子水平明显高于WKY组:SHR大剂量黄芪组血管平滑肌钙离子水平较SHR生理盐水组明显降低.结论:大剂量黄芪注射液能显著增加SHR心肌SERCA在蛋白水平的表达,能明显的减少SHR血管平滑肌钙离子的水平.     

p38丝裂原激活蛋白激酶对人胚胎肾293细胞一氧化氮合酶基因转录的调控

目的探讨p38 丝裂原激活蛋白激酶(MAPK)家族四种亚型对诱导型一氧化氮合酶(iNOS)基因的转录调控。方法以人胚胎肾293(HEK 293)细胞为靶细胞,采用脂质体(LPS)介导的细胞基因共转染技术、荧光素酶报告基因技术,分别将FLAG-tagged p38 MAPK 4种亚型、含有鼠iNOS基因启动子区的荧光素酶报告基因质粒(piNOS-Luc)、空载体(pcDNA3)、β-半乳糖苷酶表达质粒(pCMV-β)共转染,检测并比较荧光素酶相对活性。结果(1)未加刺激时,在HEK 293细胞中,p38 MAPK中仅有p38α能够诱导iNOS基因启动子的转录活性;(2)在LPS刺激下,p38 MAPK 4种亚型均能够诱导iNOS启动子的转录活性,其中,p38β所诱导的转录活性最高,p38α的诱导作用亦很明显。结论(1)LPS能够在HEK 293细胞中诱导iNOS基因转录活性;(2)在HEK 293细胞中,p38 MAPK参与了静息时及LPS刺激下对iN-OS基因的转录调控。     

Prevalence of silent myocardial ischemia in asymptomatic individuals with subclinical atherosclerosis detected by electron beam tomography

BACKGROUND: Electron beam tomography coronary calcium imaging is an evolving technique for the early detection of coronary atherosclerosis, and recent studies have established its prognostic value in asymptomatic individuals. The relationship of coronary artery calcium scores (CAC) to obstructive coronary artery disease (CAD) has been poorly studied but is clinically relevant because it determines which individuals are likely to benefit from revascularization procedures. Hence, we prospectively evaluated the prevalence of myocardial ischemia in asymptomatic patients with cardiovascular risk factors and subclinical atherosclerosis. METHODS AND RESULTS: We studied 864 asymptomatic patients with no previous CAD but with cardiovascular risk factors, referred for electron beam tomography coronary calcium imaging to our institution over an 18-month period. From this group, 220 consecutive patients (85% men; mean age, 61 +/- 9 years; age range, 31-84 years) with moderate to severe atherosclerotic disease (coronary calcium score > or =100 Agatston units) were prospectively evaluated by technetium 99m sestamibi single photon emission computed tomography (SPECT). Patients were followed up (mean follow-up, 14 months) and data regarding their subsequent clinical management recorded. Of the 220 patients, 119 had moderate atherosclerosis (CAC score of 100-400 Agatston units) and 101 had severe atherosclerosis (CAC score > or =400 Agatston units). Abnormal SPECT findings were seen in 18% of patients with moderate atherosclerosis (n = 21) and 45% of patients with severe atherosclerosis (n = 45). Increasing severity of atherosclerosis was related to increasing ischemic burden (summed difference score = 1 +/- 0.2 for CAC score of 100-400 Agatston units and 3.2 +/- 0.5 for CAC score > or =400 Agatston units). In a multivariate linear regression model incorporating risk factors, CAC was the only predictor of silent ischemia. CONCLUSION: In comparison to previously published data, we detected a higher prevalence of silent ischemia even in patients with moderate coronary atherosclerosis (18%). This may reflect the differing risk factor profile of our patient population. When coronary calcium screening is used to preselect asymptomatic patients with cardiovascular risk factors for myocardial perfusion imaging, the optimum coronary calcium score threshold will depend on the population prevalence of risk factors and asymptomatic obstructive CAD.     

Ca^＋＋对链霉素抗原—抗体反应的抑制作用

为探讨临床中使用钙制剂抢救链霉素过敏休克病人有良好效果的原因,由被动血凝试验、被动皮肤过敏试验和ELISA法证实,Ca~( )可以抑制链霉素抗原-抗体的反应。这种抑制作用是通过Ca~( )链霉素抗原结合,封闭链霉素抗原决定簇来加以实现的。     

碘杂环化合物对离体豚鼠心乳头肌动作电位和收缩力的作用

采用细胞内微电极记录技术,同步观察了3,6-[二甲氨基]-二苯并碘因甲酸盐(IHC-64)对豚鼠心乳头肌细胞动作电位和收缩力的作用。50μmol/L IHC-64抑制心肌收缩力,而不影响快反应动作电位。增加IHC-64浓度,动作电位0相最大峰值(APA)、除极速率(dp/dt_(max))和复极50％和90％时程(APD_(50)、APD_(90))被明显抑制。IHC-64抑制慢反应动作电位,提高细胞外钙浓度可拮抗这种抑制。结果提示,IHC-64主要抑制慢Ca~(2+)内流,同时也部分抑制快Na~+内流,它可能是一种新型B类钙通道阻滞剂。     

兔孤束核区微量注射γ-氨基丁酸的降压效应

在53只乌拉坦麻醉家兔身上,观察到延髓孤束核(NTS)区注射γ-氨基丁酸(GABA)使血压显著下降,安定(DZ)有相似的降压效应,荷包牡丹碱(BIC)和印防己毒素(PIC)则使血压升高;促甲状腺素释放激素(TRH)和甲硫脑啡肽(MTP)对血压无明显影响;延髓的另一些区域应用GABA等药物后血压变化不明显;提示GABA能神经递质系统参与心血管活动的抑制性中枢调节,NTS区是其作用部位之一。     

Inadequate dietary magnesium intake increases atherosclerotic plaque development in rabbits

Epidemiological studies have shown dietary magnesium (Mg) intake and serum Mg levels to be inversely correlated with the development of atherosclerosis. We hypothesized that low levels of Mg would promote atherosclerotic plaque development in rabbits. New Zealand white rabbits (4 months old, n = 22) were fed an atherogenic diet containing 0.12% (−Mg), 0.27% (control), or 0.43% (+Mg) Mg for 8 weeks. Blood samples were obtained at baseline, 2, 4, 6, and 8 weeks and were assayed for total cholesterol, high-density lipoprotein (HDL), non-HDL, triglycerides (TG), C-reactive protein, serum Mg, and erythrocyte Mg. Aortas from −Mg had significantly more plaque, with an intima thickness 42% greater than control and 36% greater than +Mg. Serum cholesterol levels rose over time, and at 8 weeks, −Mg had the highest and +Mg the lowest total and non-HDL cholesterol and TG levels, although these results did not reach significance. Over time, serum Mg levels increased, and erythrocyte Mg levels decreased. C-reactive protein significantly increased in all groups at 4 and 6 weeks but returned to baseline levels by 8 weeks. This study supports the hypothesis that inadequate intake of Mg results in an increase in atherosclerotic plaque development in rabbits.     

The in vitro elution characteristics of vancomycin and tobramycin from calcium sulfate beads

The purpose of this study was to determine the elution characteristics of vancomycin and tobramycin when mixed with calcium sulfate to form antibiotic beads. Calcium sulfate was combined with vancomycin and tobramycin separately to form 2 types of antibiotic beads, which were packaged and labeled separately. The packaged calcium sulfate beads with vancomycin and tobramycin were then gas sterilized. The beads were placed in phosphate-buffered saline and kept at 36 degrees C for 6 weeks. Two separate series of assays were run simultaneously for both types of beads. In one assay, a bead containing vancomycin was placed in a fresh vial of phosphate buffered saline after each assay. The same was done with beads containing tobramycin. In the second series of assays, 9 vials of phosphate buffered saline each containing 1 vancomycin bead and 9 vials of phosphate buffered saline each containing 1 tobramycin bead was arranged. The phosphate-buffered saline was then assayed at predetermined times for both the vancomycin bead series and the tobramycin bead series. The amount of vancomycin and tobramycin assayed nearly equaled the calculated amount of antibiotic per bead measured before bead construction. Also, the elution of antibiotic from the calcium sulfate was complete within 72 hours. In conclusion, the construction and gas sterilization of calcium sulfate beads containing vancomycin and tobramycin does not destroy vancomycin and tobramycin. Also, the complete elution of available vancomycin and tobramycin in calcium sulfate beads occurs within 72 hours.