Circulating endothelial progenitor cells and coronary collaterals in patients with non-ST segment elevation myocardial infarction

BACKGROUND: Endothelial progenitor cells (EPCs) are bone marrow-derived cells that are augmented in response to ischemia and incorporated into neovascularization sites. We sought to determine whether circulating EPCs are related to collateral formation following non-ST segment elevation myocardial infarction (NSTEMI). METHODS: Twenty patients who underwent percutaneous coronary intervention (PCI) within a week of NSTEMI were divided into two groups: patients without collaterals (coll-, n=10) and patients with Rentrop grade 3--4 collaterals (coll+, n=10). Blood samples were drawn before PCI and 24+/- 2 h after PCI. EPC colonies were grown from peripheral blood mononuclear cells, characterized, and counted. Using flow cytometry the percentage of cells co expressing vascular endothelial growth factor receptor-2 and CD 133 was determined. RESULTS: The coll+ group had higher degree of culprit vessel stenosis and lower initial thrombolysis in myocardial infarction flow grade. The relative number of EPCs before PCI was significantly higher in the coll+ group than in the coll- group (1.49 +/- 0.9% vs. 0.77+/- 0.4%, p= 0.045). There were no significant intergroup differences in the number of EPC colony-forming cells. The number of EPC colonies increased in the coll- group after PCI (9.5 +/- 4.8 to 14.0 +/- 5.9/10(6) cells, p=0.01). CONCLUSIONS: This study supports an association between circulating EPC levels and collateral formation in patients with an NSTEMI.     

The role of nutricline depth in regulating the ocean carbon cycle

Carbon uptake by marine phytoplankton, and its export as organic matter to the ocean interior (i.e., the “biological pump”), lowers the partial pressure of carbon dioxide (pCO₂) in the upper ocean and facilitates the diffusive drawdown of atmospheric CO₂. Conversely, precipitation of calcium carbonate by marine planktonic calcifiers such as coccolithophorids increases pCO₂ and promotes its outgassing (i.e., the “alkalinity pump”). Over the past ≈100 million years, these two carbon fluxes have been modulated by the relative abundance of diatoms and coccolithophores, resulting in biological feedback on atmospheric CO₂ and Earth's climate; yet, the processes determining the relative distribution of these two phytoplankton taxa remain poorly understood. We analyzed phytoplankton community composition in the Atlantic Ocean and show that the distribution of diatoms and coccolithophorids is correlated with the nutricline depth, a proxy of nutrient supply to the upper mixed layer of the ocean. Using this analysis in conjunction with a coupled atmosphere–ocean intermediate complexity model, we predict a dramatic reduction in the nutrient supply to the euphotic layer in the coming century as a result of increased thermal stratification. Our findings indicate that, by altering phytoplankton community composition, this causal relationship may lead to a decreased efficiency of the biological pump in sequestering atmospheric CO₂, implying a positive feedback in the climate system. These results provide a mechanistic basis for understanding the connection between upper ocean dynamics, the calcium carbonate-to-organic C production ratio and atmospheric pCO₂ variations on time scales ranging from seasonal cycles to geological transitions.     

颈动脉狭窄的筛查美国预防服务特别工作组对证据的更新

背景 在美国,脑血管病是导致死亡的第3位原因.在所有卒中病例中,由既往无症状颈动脉狭窄(carotid artery stenosis,CAS)造成的比例并不高.1996年,美国预防服务特别工作组得出结论,没有充分的证据推荐或反对通过体格检查或颈动脉超声在无症状患者中对CAS进行筛查.目的 评估采用双功能超声对无症状患者进行筛查以及应用颈动脉内膜切除术(carotid endarterectomy,CEA)对CAS进行治疗的利弊.数据来源 Medline和Cochrane数据库(检索日期为1994年1月-2007年4月)、最近的系统评价、检索文章的参考文献以及专家的建议.研究选择 选择对CAS进行筛查的英文随机对照试验(randomized controlled trial,RCT)、对CEA与药物治疗进行比较的RCT、筛查试验的系统评价以及对CEA害处的观察性研究,以回答下列问题:是否有直接证据表明使用超声筛查无症状CAS能降低卒中风险? 超声检测CAS的准确性如何? CEA治疗能否降低卒中残疾率或病死率? CAS筛查或CEA治疗是否会给患者带来伤害? 数据提取 使用预先确定的特殊工作组标准,对所有研究进行评估、提炼和质量评定.数据综合 至今尚未进行过CAS筛查的RCT.根据系统评价,超声检测CAS的敏感性约为94%,特异性约为92%.在经过选择的患者中由选定的外科医生进行手术治疗可使5年卒中风险降低约5%.在RCT中,CEA的30 d卒中和死亡发生率为2.7%～4.7%,而在观察性研究中的发生率更高(高达6.7%).局限性 证据不足以对有临床意义的CAS进行风险分层.对患者行CEA与药物治疗相比较的RCT是在经过选择的人群中由特定的外科医生实施的.结论 对无症状患者进行CAS筛查以及进行CEA治疗造成的实际卒中风险降低率尚不清楚;由于整个无症状人群中可治疗疾病的总体患病率不高且治疗会造成一定的害处,因此筛查的益处受到限制.     

Six-year clinical and immunologic follow-up of workers exposed to trimellitic anhydride

We report a 6-year study from 1979 through 1985 of workers exposed to trimellitic anhydride (TMA) in three groups of volunteers. Twenty-nine percent of workers (5/17) originally studied had immunologically induced respiratory disease. Subsequent to this evaluation, increased environmental control of TMA exposure was instituted. Since that time, there have been decreasing clinical symptoms and decreasing levels of antibody against TMA conjugated to human serum albumin. These long-term studies originally used radioimmunoassays, but enzyme-linked immunoassays against TMA-conjugated proteins are now demonstrated to be equally appropriate and are more cost-effective. With appropriate clinical and immunologic studies, immunologic airway reactions to TMA may be identified and then prevented by environmental control to decrease inhalation exposure to TMA. This is likely applicable to certain other chemical antigens that immunize by inhalation.