Role of proximal electrode position in transvenous ventricular defibrillation

Transvenous defibrillation lead systems have been demonstrated to reduce operative morbidity and mortality associated with implantation of cardioverter-defibrillators. To determine the best position for the proximal electrode in transvenous systems, defibrillation thresholds were compared for three positions in a single-pathway, two-lead system. Two defibrillation lead electrodes were transvenously inserted into seven dogs. The distal electrode was positioned in the right ventricular apex. The proximal electrode was randomized to one of three positions: (1) the superior (cranial) vena cava (SVC) at he junction of the right atrium, (2) the left innominate vein at the junction of the SVC, or (3) the external jugular vein. Biphasic defibrillation thresholds for converting electrically induced ventricular fibrillation were determined for the three positions of the proximal electrode in each dog. The innominate vein position resulted in the lowest defibrillation threshold (555±123 V) as compared to the SVC (640±126 V;p=0.0612) and the jugular vein (709±117 V;p=0.0013). Lead impedance gradually increased with increasing dostamce between the two shocking electrodes: 58.4±11.4 Ω for SVC, 76.2±13.8 Ω for innominate vein, and 94.9±10.2 Ω for jugular vein proximal lead electrode position (p<0.05 for all pairwise comparisons). In two-electrode transvenous defibrillation lead systems, positioning the proximal electrode in the left innominate vein produced the lowest defibrillation threshold.     

佛山市高明区283名铅作业工人职业健康检查结果分析

目的通过了解铅对作业工人健康状况的影响,为采取有效的保护措施提供依据。方法选取2012年佛山市高明区某企业283名铅作业工人的职业健康检查结果进行分析。结果283名铅作业工人平均血铅浓度为（388．30±197．49）μ/L,有130人的血铅超过400μg/L,超标率为45．94％;心电图异常检出率最高,达20．85％;血铅与血红蛋白间不存在显著的线性相关关系。结论企业应积极改进生产工艺,改善生产环境,加强防护措施,定期对工人进行体检。     

天麻阿胶联合对染铅鼠脑一氧化氮及学习记忆的影响

目的 观察天麻和阿胶联合对染铅大鼠学习记忆损害的拮抗作用.方法 Wistar雄性大鼠经口染铅并分别单独及联合给予天麻(4.0g·kg^-1·d^-1)和阿胶(1.0g·kg^-1·d^-1)灌胃,连续3个月;每月用游泳试验(水中寻找平台试验)测试学习记忆1次,最后处死大鼠测定小脑组织一氧化氮含量.结果 在游泳试验中,高铅对照组和低铅对照组大鼠15次中直线到达平台次数,与空白组比较差异均非常显着(P<0.01).天麻单用即可显着增加染铅大鼠直线到达平台的次数(第1月P<0.05,第2,3月P<0.01);阿胶单用亦可显着增加染铅大鼠在游泳试验中直线到达平台次数(P<0.05);天麻和阿胶联用更能显着增加染铅大鼠在游泳试验中直线到达平台次数,与二者单用相比差异非常显着(P<0.01).小脑组织一氧化氮测定:高铅对照组和低铅对照组大鼠小脑一氧化氮,与空白组比较差异均非常显着(P<0.01);天麻单用即可显着提高染铅大鼠小脑一氧化氮(P<0.05,低铅时P<0.01);阿胶单用也可显着提高染铅大鼠小脑一氧化氮(P<0.05);天麻和阿胶联用更能显着提高染铅大鼠小脑一氧化氮含量,与二者单用相比差异非常显着(P<0.01).结论 天麻和阿胶单用即可显着减轻铅对学习记忆的损害作用,二者联用效果更为显著.     

幼儿铅负荷来源及其对神经行为影响的研究

目的探讨铅吸收的来源及铅暴露对学龄前儿童的影响.方法随机整体抽取太原市居民区某幼儿园211名4～6岁幼儿为对照组,工业区某幼儿园同年龄组96名为观察组,用火焰和石墨炉原子吸收法,测定两幼儿园空气、土壤、饮水、手尘铅含量及幼儿末梢血铅值,采用Achenbach儿童行为量表(CBCL)及自拟调查表作问卷调查.结果观察组空气、土壤、手尘及血铅水平均显著高于对照组(P＜0.05),血铅与手尘铅显著正相关(r=0.3084,P＜0.05),观察组外向行为得分,行为问题发生率均显著高于对照组(P＜0.05).多元逐步回归分析表明不良的卫生习惯是影响血铅水平的首要因素,手一口接触是铅进入机体主要途径,血铅值进入攻击、多动、违纪的回归方程.结论不良的卫生习惯直接影响幼儿铅负荷水平,铅暴露对外向行为产生负性影响.     

Significance of exercise-induced ST changes in leads aVR,V5, and V1. Discrimination of patients with single- or multivessel coronary artery disease

BACKGROUND: It is known that exercise-induced ST-segment elevation in lead V1 (V1-E) detects left anterior descending (LAD) stenosis. It was also postulated that ST elevation in aVR and simultaneous ST depression in V5 (aVR-E + V5-D) is a marker of ischemia due to significant stenosis of the LAD in patients with single-vessel disease. HYPOTHESIS: This study was undertaken to investigate the significance of the concomitant appearance of both electrocardiographic (ECG) ischemic markers, and of each of them alone during exercise, to detect either LAD stenosis as single-vessel coronary artery disease (CAD), or multivessel CAD involving LAD stenosis. METHODS: A total of 196 consecutive patients (152 men and 44 women, mean age 54 +/- 7 years) with at least one of these ECG markers, who underwent treadmill exercise testing with the Bruce protocol and coronary arteriography, were studied. RESULTS: Patients were divided into three groups. In Group A (83 patients with V1-E + aVR-E & V5-D), 93% of patients with single-vessel disease had significant LAD stenosis (p<0.001), whereas 75% of patients with double-vessel disease had significant stenoses of the LAD and the left circumflex (LCx) coronary arteries (p<0.01). In Group B (97 patients with aVR-E & V5-D but without V1-E), 43% of patients with single-vessel disease had significant LAD stenosis (p<0.08), whereas 85% of patients with double-vessel disease had significant stenoses of the LAD and the right coronary artery (RCA) (p<0.01). In Group C (16 patients with only V1-E), 60% of patients with single-vessel disease had significant LAD stenosis (p<0.05), whereas 75% of patients with double-vessel disease had significant LAD and LCx stenoses (p<0.05). CONCLUSIONS: The concomitant appearance of exercise-induced ST elevation in lead V1, ST elevation in lead aVR, and ST depression in lead V5, as well as the isolated appearance of ST elevation in lead V1 detect significant LAD stenosis as single-vessel disease, or significant stenoses of LAD and LCx arteries in patients with double-vessel disease, whereas the appearance of ST elevation in aVR & ST depression in V5 but without ST elevation in V1 correlates strongly with significant LAD and RCA stenoses and usually indicates double-vessel disease.     

Blood lead levels in children after phase-out of leaded gasoline in Kinshasa,the capital of Democratic Republic of Congo (DRC)

Background

The phasing out of lead from gasoline has resulted in a significant decrease in blood lead levels (BLLs) in children during the last two decades. Tetraethyl lead was phased out in DRC in 2009. The objective of this study was to test for reduction in pediatric BLLs in Kinshasa, by comparing BLLs collected in 2011 (2 years after use of leaded gasoline was phased out) to those collected in surveys conducted in 2004 and 2008 by Tuakuila et al. (when leaded gasoline was still used).

Methods

We analyzed BLLs in a total of 100 children under 6 years of age (Mean ± SD: 2.9 ± 1.6 age, 64% boys) using inductively coupled argon plasma mass spectrometry (ICP – MS).

Results

The prevalence of elevated BLLs (≥ 10 μg/dL) in children tested was 63% in 2004 [n = 100, GM (95% CI) = 12.4 μg/dL (11.4 – 13.3)] and 71% in 2008 [(n = 55, GM (95% CI) = 11.2 μg/dL (10.3 – 14.4)]. In the present study, this prevalence was 41%. The average BLLs for the current study population [GM (95% CI) = 8.7 μg/dL (8.0 – 9.5)] was lower than those found by Tuakuila et al. (F = 10.38, p <0.001) as well as the CDC level of concern (10 μ/dL), with 3% of children diagnosed with BLLs ≥ 20 μg/dL.

Conclusion

These results demonstrate a significant success of the public health system in Kinshasa, DRC-achieved by the removal of lead from gasoline. However, with increasing evidence that adverse health effects occur at BLLs < 10 μg/dL and no safe BLLs in children has been identified, the BLLs measured in this study continue to constitute a major public health concern for Kinshasa. The emphasis should shift to examine the contributions of non-gasoline sources to children’s BLLs: car batteries recycling in certain residences, the traditional use of fired clay for the treatment of gastritis by pregnant women and leaded paint.     

Tea catechins protect against lead-induced cytotoxicity, lipid peroxidation, and membrane fluidity in HepG2 cells.

Recent studies have shown that lead causes oxidative stress by inducing the generation of reactive oxygen species (ROS) and reducing the antioxidant defense system of cells. This suggests that antioxidants may play an important role in the treatment of lead poisoning as a kind of excellent scavenger of free radicals and chelator of heavy metal. Whether tea catechins have protective effects against oxidative stress after lead treatment in cell systems remains unclear. The present study was designed to elucidate if tea catechins have any protective effects on lipid peroxidation damage in lead-exposed HepG2 cells. Exposure of HepG2 cells to Pb(++) decreased cell viability and stimulated lipid peroxidation of cell membranes as measured by the thioburbituric acid reaction. Electron spin resonance (ESR) spin-labeling studies indicated that lead exposure could decrease the fluidity in the polar surface of cell membranes. Tea catechin treatment significantly increased cell viability, decreased lipid peroxidation levels, and protected cell membrane fluidity in lead-exposed HepG2 cells in a concentration-dependent manner. The galloylated catechins showed a stronger effect than nongalloylated catechins. Cotreatment with (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG) showed a synergistically protective effect. The results suggest that tea catechin supplementation may have a role to play in modulating oxidative stress in lead-exposed HepG2 cells.     

Determinants of bone and blood lead concentrations in the early postpartum period

OBJECTIVE—This study investigated determinants of bone and blood lead concentrations in 430 lactating Mexican women during the early postpartum period and the contribution of bone lead to blood lead.
METHODS—Maternal venous lead was measured at delivery and postpartum, and bone lead concentrations, measured with in vivo K-x ray fluorescence, were measured post partum. Data on environmental exposure, demographic characteristics, and maternal factors related to exposure to lead were collected by questionnaire. Linear regression was used to examine the relations between bone and blood lead, demographics, and environmental exposure variables.
RESULTS—Mean (SD) blood, tibial, and patellar lead concentrations were 9.5 (4.5) µg/dl, 10.2 (10.1) µg Pb/g bone mineral, and 15.2 (15.1) µg Pb/g bone mineral respectively. These values are considerably higher than values for women in the United States. Older age, the cumulative use of lead glazed pottery, and higher proportion of life spent in Mexico City were powerful predictors of higher bone lead concentrations. Use of lead glazed ceramics to cook food in the past week and increased patellar lead concentrations were significant predictors of increased blood lead. Patellar lead concentrations explained one third of the variance accounted for by the final blood lead model. Women in the 90th percentile for patella lead had an untransformed predicted mean blood lead concentration 3.6 µg/dl higher than those in the 10th percentile.
CONCLUSIONS—This study identified the use of lead glazed ceramics as a major source of cumulative exposure to lead, as reflected by bone lead concentrations, as well as current exposure, reflected by blood lead, in Mexico. A higher proportion of life spent in Mexico City, a proxy for exposure to leaded gasoline emissions, was identified as the other major source of cumulative lead exposure. The influence of bone lead on blood lead coupled with the long half life of lead in bone has implications for other populations and suggests that bone stores may pose a threat to women of reproductive age long after exposure has declined.


Keywords: postpartum; blood lead; bone lead     

正常人头胸导联和常规导联右胸异常Q波的比较

目的:比较常规导联心电图及头胸导联心电图所记录的正常人右胸导联Q波的特征.材料与方法:采用导联心电图机及头胸导联心电图机分别检查50个正常成人(30名男性,20名女性)的右胸心电图,记录Q波出现的频率及幅度.结果:头胸导联所记录到的Q波数及Q波幅度均显著低于常规导联心电图.结论:正常人头胸导联心电图较常规心电图较少出现右胸假性异常Q波.     

铅对儿童骨代谢的影响

【目的】　通过对山西省某铅污染较重矿区儿童血铅水平及骨代谢生化指标的测定 ,探讨血铅对儿童骨代谢的影响。　【方法】　整群抽取 5～ 6岁儿童 12 0名 ,应用石墨炉原子吸收光谱法测定血铅值 ;通过酶联免疫法(ELISA)检测本组儿童血清骨钙素 (OC)、骨碱性磷酸酶 (BALP)及 2 5 (OH)D3 水平。　【结果】　随着血铅水平的增高 ,该组儿童的血清OC和 2 5 (OH)D3 水平呈下降趋势 ,而BALP呈上升趋势。其中Ⅲ级铅中毒儿童血清OC较Ⅰ级铅中毒儿童显著下降 (P <0 .0 1) ,而血清BALP显著增高 (P <0 .0 1) ,且Ⅱ级铅中毒儿童血清BALP较Ⅰ级铅中毒儿童已有显著增高改变 (P <0 .0 1)。另外 ,相关性分析表明本调查组儿童血铅水平与OC和 2 5 (OH )D3 呈负相关而与BALP呈正相关。　【结论】　铅中毒可抑制成骨细胞的活动 ,阻碍生长期儿童骨的正常矿化过程