血浆BNP变化对慢性心功能不全诊断的意义

目的探讨血浆B型利钠肽（BNP）与慢性心功能不全的关系。方法根据Framingham诊断标准纳入的60例慢性心功能不全患者,按NYHA分级,采用Triage快速定量测定仪检测BNP。结果Ⅰ～Ⅳ级各组患者,BNP水平逐渐升高;心功能Ⅳ级组患者BNP水平高于心功能Ⅱ级组和Ⅲ级组（P〈0.05）;而心功能Ⅱ级、Ⅲ级和Ⅳ级组均高于心功能Ⅰ级组（P〈0.05）。结论 BNP是评价慢性心功能不全患者心脏功能状态的有效指标。     

老年心功能不全患者缺血修饰白蛋白水平的变化及其对转归的评估

目的 研究老年心功能不全患者缺血修饰白蛋白(IMA)水平在不同心功能状态时的变化.方法 64 例心功能不全患者,按NYHA 分级分为心功能Ⅱ、Ⅲ、Ⅳ级,依据其转归将其分为症状缓解组及病情加重/死亡组,记录患者一般情况、发病及就诊时间,测定各组治疗前后血浆IMA、BNP 水平.结果 心功能Ⅱ级的血清IMA 明显低于心功能Ⅲ级和Ⅳ级(P ＜0.05);心功能Ⅳ级和心功能Ⅱ、Ⅲ级IMA 最适临界值为9.82 U/ml,曲线下面积为0.834,敏感度为81.6%,特异度为46.1%;症状缓解组治疗后IMA、BNP 均降低且治疗前后IMA、BNP 比较有统计学差异(P ＜0.05);病情加重/死亡组治疗后IMA、BNP 均升高且治疗前后IMA、BNP 比较也有统计学差异(P ＜0.05);病情加重/死亡组IMA、BNP 值明显高于缓解组(P ＜0.05);治疗前后血IMA 与BNP 没有相关性(P ＞0.05).结论 老年心功能不全患者血浆IMA 浓度显著升高,并随NYHA 心功能分级的增高而升高,经过治疗病情平稳后IMA 水平回落;检测血清IMA 浓度有助于老年心功能不全的诊断及病情评估,并可作为疗效判断、预后评估的重要指标之一;IMA 对老年心功能不全患者的转归判断可能强于BNP,但对心力衰竭诊断的特异性不如BNP.     

血清脑钠肽水平与老年慢性心力衰竭患者心功能的相关性

目的探讨血清脑钠肽(BNP)和超声心动图在评估慢性心力衰竭(CHF)患者心功能中的临床价值。方法选择120例CHF患者为观察组,同期体检的健康人群120例作为对照组,比较不同心功能分级比较超声心电图参数及BNP水平、左心射血分数(LVEF)和左心室舒张末期内径(LVEDD)。并按照心功能分级和BNP是否正常进行分组,分析血清BNP和超声心动图与心功能分级相关性,评价血清BNP和超声心动图在评估CHF心功能分级中的价值。结果观察组的血清BNP、LVEDD水平均高于对照组,LVEF低于对照组,差异有统计学意义(P0.05)。按照心力衰竭级别分组,各组间的BNP水平不同,且任意两组间的BNP有统计学差异,随着心力衰竭级别的增加,BNP逐渐增加(P0.05);随着心力衰竭级别的增加,LVEF逐渐降低(P0.05);各组间的LVEDD不同,且心力衰竭Ⅲ级与Ⅰ级、Ⅳ级与Ⅰ级、Ⅳ级与Ⅱ级间差异有统计学意义(P0.05);随着心力衰竭级别的增加,BNP水平逐渐增加(P0.05)但LVEF水平逐渐降低(P0.05);各组间的LVEDD不同,且心力衰竭Ⅲ级与Ⅰ级、Ⅳ级与Ⅰ级、Ⅳ级与Ⅱ级间差异有统计学意义(P0.05)。血清BNP与LVEF呈负相关,但与LVEDD呈正相关(P0.05);BNP升高组患者的年平均住院次数、住院时间均高于对照组,差异有统计学意义(P0.05)。结论血清BNP和LVEF、LVEDD参数一起用于CHF患者心功能评估,可提高评估准确性,为病情评估、临床治疗提供理论指导依据。     

血清miRNA-21、miRNA-126异常表达对慢性心力衰竭患者的临床意义

目的探讨循环血清miRNA-21、miRNA-126检测对慢性心力衰竭患者的临床意义。方法选取该院收治的慢性心力衰竭患者128例(CHF组)为研究对象(NYHA心功能Ⅱ级40例,NYHA心功能Ⅲ级46例,NYHA心功能Ⅳ级42例),另选择同期100例体检中心健康患者为对照组,采用实时荧光定量PCR(qPCR)检测血清miRNA-21和miRNA-126水平,同时测定CHF患者B型脑钠肽(BNP)、左室舒张末内径(LVEDD)和左室射血分数(LVEF),并进行统计学分析。结果 CHF组患者血清miRNA-21和miRNA-126水平显著高于健康对照组(P0.05);心功能Ⅳ级患者miRNA-21水平显著高于心功能Ⅱ级、Ⅲ级患者(P0.05),心功能Ⅲ级患者miRNA-21显著高于心功能Ⅱ级患者(P0.05);心功能Ⅳ级患者miRNA-126水平显著高于心功能Ⅱ级、Ⅲ级患者(P0.05),但是心功能Ⅱ级、Ⅲ级患者间比较差异无统计学意义(P0.05);CHF患者血清miRNA-21水平与BNP(r=0.792,P=0.001)、LVEDD(r=0.618,P=0.003)呈正相关,与LVEF呈负相关(r=-0.521,P=0.010),血清miRNA-126水平与BNP呈正相关(r=0.753,P=0.001),与LVEDD(r=0.207,P=0.096)、LVEF(r=-0.159,P=0.176)无明显相关性;血清miRNA-21(RR:2.158,95%CI:1.681~3.539,P=0.005)和miRNA-126(RR:1.852,95%CI:1.105~2.996,P=0.012)均是CHF的独立危险因素。结论慢性心力衰竭患者血清miRNA-21、miRNA-126水平异常升高,二者可能参与了慢性心力衰竭的发生与进展,是其独立危险因素。     

慢性心力衰竭患者BNP、hs-CRP水平检测的临床意义

目的探讨B型钠尿肽(BNP)、高敏C反应蛋白(hs-CRP)联合检测对慢性心力衰竭(CHF)患者的价值。方法将194例CHF患者按美国纽约心脏病学会(NYHA)心功能分级标准分为Ⅰ级38例、Ⅱ级56例、Ⅲ级59例、Ⅳ级41例,以60名健康体检者作为正常对照组,检测各组血清BNP及hs-CRP水平。结果 CHF组hs-CRP及BNP均明显高于正常对照组(P0.05、P0.01)。CHF组NYHAⅠ~Ⅳ级BNP水平逐渐升高,各级间比较差异有统计学意义(P0.05、P0.01);hs-CRP各级间差异均无统计学意义(P0.05)。结论检测CHF患者血清BNP和hs-CRP对了解CHF病情严重程度、预后判断具有一定的指导意义。     

血浆脑钠肽和血清肌钙蛋白 I 在老年慢性心力衰竭中的临床研究

目的 探讨血浆脑钠肽（BNP）及血清肌钙蛋白I（cTNI）含量改变在老年患者发生充血性心力衰竭时的临床意义。 方法 选择2010年7月－2012年8月住院的各种老年心脏病患者117例,根据纽约心功能分级分为4组（心功能Ⅰ级组、Ⅱ级组、Ⅲ级组、Ⅳ级组）,分别检测血浆BNP、血清cTNI及心肌酶[肌酸磷酸激酶（CK）、肌酸磷酸激酶同工酶（CK-MB）]进行组间比较,同时与健康老年组进行对比。 结果 ① 老年慢性充血性心力衰竭各组（心功能Ⅱ～Ⅳ级）血浆BNP水平均高于健康对照组及心功能正常组（心功能Ⅰ级组）;且心功能Ⅳ级组BNP水平＞心功能Ⅲ级组＞心功能Ⅱ级组。各组之间比较差异有统计学意义,但心功能Ⅰ级组与健康对照组血浆BNP水平无明显差异。② 各组之间CK及CK-MB水平差异均无统计学意义。③ 充血性心力衰竭各组（心功能Ⅱ～Ⅳ级组血清cTNI水平均高于健康对照组及心功能正常组（心功能Ⅰ级组）;且心功能Ⅳ级组cTNI水平＞心功能Ⅲ级组＞心功能Ⅱ级组。各组之间比较差异有统计学意义,而心功能Ⅰ级组及健康对照组血清cTNI水平差异无统计学意义。 结论 血浆BNP水平及血清cTNI水平在老年患者发生心力衰竭时随心力衰竭程度加重而逐渐升高,两者均对慢性充血性心力衰竭的临床诊断具有重要参考意义。     

慢性充血性心力衰竭时血浆脑钠肽和肌钙蛋白I的含量改变

目的：探讨老年心脏病患者发生充血性心力衰竭时血浆脑钠肽（BNP）及肌钙蛋白Ⅰ（cTNI）含量改变及临床意义。方法：选择2006-01-2011-03在我院住院的各种老年心脏病患者235例,根据纽约心功能分级,分为4组（心功能Ⅰ级组、Ⅱ级组、Ⅲ级组、Ⅳ级组）,分别检测血浆脑钠肽、肌钙蛋白I及心肌酶（CK、CK-MB）,进行组间比较,同时与健康老年组进行对比。结果：①老年心脏病慢性充血性心力衰竭各组（心功能Ⅱ～Ⅳ级）血浆BNP水平均高于健康对照组及心功能正常组（心功能Ⅰ级组）;且心功能Ⅳ级组BNP水平〉心功能Ⅲ级组〉心功能Ⅱ级组。各组之间比较,差异有统计学意义。但心功能Ⅰ级组与健康对照组血浆BNP水平无明显差异。②各组之间CK及CK-MB水平差异均无统计学意义。③充血性心力衰竭各组（心功能Ⅱ～Ⅳ级）血浆cTNI水平均高于健康对照组及心功能正常组（心功能Ⅰ级组）;且心功能Ⅳ级组cTNI水平〉心功能Ⅲ级组〉心功能Ⅱ级组。各组之间比较,差异有统计学意义。而心功能Ⅰ级组及健康对照组血浆cTNI水平差异无统计学意义。结论：血浆BNP水平及肌钙蛋白水平在老年人不同程度的充血性心力衰竭时均较正常人及慢性心脏病患者心功能正常时增高,且心功能损害程度越重,血浆BNP及肌钙蛋白I水平越高。两者均对慢性充血性心力衰竭的临床诊断具有重要参考意义。在临床诊断过程中,如能结合临床表现及其他检查结果,同时参考血浆BNP及肌钙蛋白水平,将会明显增加对慢性充血性心力衰竭诊断的及时性及正确性。     

血清PⅢNP、IGF-1水平与冠心病慢性心力衰竭患者心功能的相关性

目的 检测慢性心力衰竭(CHF)患者血清Ⅲ型前胶原氨基端肽(PⅢNP)、胰岛素样生长因子-1(IGF-1)水平,并探讨二者与CHF患者心功能的关系。方法 选取2019年2月至2020年5月于宝鸡市中心医院心内科住院的197例CHF患者为研究对象,根据心功能分级将患者分为CHFⅠ/Ⅱ级组64例、CHFⅢ级组71例和CHFⅣ级组62例;另选取同期该院68例体检健康者作为对照组。采用酶联免疫吸附试验检测血清PⅢNP、IGF-1及N-末端脑钠肽前体(NT-proBNP)水平;采用三维超声心动图检测患者心功能参数;分析CHF患者血清PⅢNP、IGF-1与心功能的相关性;采用Logistic回归分析发生CHF的影响因素。结果 CHFⅣ级组血清PⅢNP、IGF-1水平高于CHFⅢ级组、CHFⅠ/Ⅱ级组和对照组,CHFⅢ级组血清PⅢNP、IGF-1水平高于CHFⅠ/Ⅱ级组和对照组,CHFⅠ/Ⅱ级组血清PⅢNP、IGF-1水平高于对照组,差异均有统计学意义(P<0.05)。CHFⅣ级组左心室舒张末期内径(LVEDD)、左心室收缩末内径(LVESD)、NT-proBNP水平高于CHFⅢ级组、CHFⅠ...     

联合检测血清BNP、GDF-15、MMP-9对慢性心力衰竭患者心功能的评估价值分析

目的 探讨联合检测血清B型脑钠肽（Brain natriuretic peptide,BNP）、生长分化因子-15(CDF-15)、基质金属蛋白酶-9(MMP-9)对慢性心力衰竭（Congestive heart failure,CHF）患者心功能的评估价值。方法 选取收治的93例CHF患者，依据美国纽约心脏病协会（New York Heart Association,NYHA）心功能分级评估患者心功能情况，检测并对比不同心功能分级CHF患者血清BNP、CDF-15、MMP-9水平，分析单独及联合检测血清BNP、CDF-15、MMP-9对CHF患者心功能的评估价值。结果 93例CHF患者中NYHA心功能分级Ⅰ级22例，Ⅱ级29例，Ⅲ级23例，Ⅳ级19例；心功能分级Ⅳ级CHF患者血清BNP、CDF-15、MMP-9水平依次高于Ⅲ级、Ⅱ级、Ⅰ级患者，且Ⅲ级依次高于Ⅱ级、Ⅰ级，Ⅱ级高于Ⅰ级，差异有统计学意义（P<0.05）；经Pearson相关性检验分析发现，血清BNP、CDF-15、MMP-9水平与CHF患者心功能分级均呈正相关（r>0,P<0.05）；绘制ROC曲线发现...     

不同剂量缬沙坦治疗慢性心功能不全的效果观察

目的探讨不同剂量缬沙坦治疗慢性心功能不全的效果。方法选取2015年1月至2016年1月96例慢性心功能不全患者,随机分成Ⅰ组、Ⅱ组、Ⅲ组,每组32例。三组患者均采用常规方法治疗,Ⅱ组、Ⅲ组予以缬沙坦,应用剂量分别为80 mg/d、160 mg/d,观察治疗前与治疗4周、12周后的脑钠肽(BNP)、血管紧张素Ⅱ(AngⅡ)、血浆肾素(PRA)及左室舒张末期容积指数(LVEDVI)、左室射血分数(LVEF)变化。结果治疗4周、12周后,Ⅱ组、Ⅲ组LVEDVI低于Ⅰ组,Ⅲ组LVEF与Ⅰ组比较明显提高(P0.05);Ⅱ、Ⅲ组间BNP、AngⅡ、PRA水平比较差异有统计学意义(P0.05)。结论缬沙坦治疗慢性心功能不全效果显著,160 mg/d可明显逆转慢性心功能不全患者心室重构,改善心功能,不良反应少,临床应用价值更高。     

Guns and Knives in New Mexico: Patterns of Penetrating Trauma, 1978–1993

Objective: To identify patterns of nonfatal and fatal penetrating trauma among children and adults in New Mexico using ED and medical examiner data.
Methods: The authors retrospectively sampled in 5-year intervals all victims of penetrating trauma who presented to either the state Level-1 trauma center or the state medical examiner from a 16-year period (1978–1993). Rates of nonfatal and fatal firearm and stabbing injury were compared for children and adults.
Results: Rates of nonfatal injury were similar (firearm, 34.3 per 100,000 person-years; stabbing, 35.1). However, rates of fatal injury were significantly different (firearm, 21.9; stabbing, 2.7; relative risk: 8.2; 95% confidence interval: 5.4, 12.5). From 1978 to 1993, nonfatal injury rates increased for children (p = 0.0043) and adults (p < 0.0001), while fatal penetrating injury remained constant. The increase in nonfatal injury in children resulted from increased firearm injury rates. In adults, both stabbing and firearm nonfatal injury rates increased.
Conclusions: Nonfatal injury data suggest that nonfatal violence has increased; fatal injury data suggest that violent death rates have remained constant. Injury patterns vary by age, mechanism of trauma, and data source. These results suggest that ED and medical examiner data differ and that both are needed to guide injury prevention programs.     

Systematic Reviews Published in the January 2011 Issue of The Cochrane Library

ABSTRACT

The Cochrane Library of Systematic Reviews is published quarterly as a DVD and monthly online. The January 2011 issue (first quarterly DVD for 2011) contains 4515 complete reviews, 1985 protocols for reviews in production, and 13,521 one-page summaries of systematic reviews published in the general medical literature. In addition, there are citations of 641,000 randomized controlled trials, and 14,018 cited papers in the Cochrane methodology register. The health technology assessment database contains over 9300 citations. One hundred and seven new reviews have been published in the last 3 months, of which five have potential relevance for practitioners in pain and palliative medicine.     

Interprofessional approaches to creating safe,high quality health care

Three supplementary perspectives are presented arguing that interprofessional collaboration is both necessary and desirable. Nonetheless, there are often too many serious intra-professional barriers and obstacles to interprofessional collaboration to make it successful. Some of these barriers, it is argued and illustrated, are found in the multiple ways in which professional identity is tacitly acquired and embodied in the practitioners' habitual, everyday practice. The paper then explores ways in which reflection, especially Second order reflection, can help to elucidate and overcome these obstacles, as well as increasing professional adaptability and competence.     

Determination of creatine kinase isoenzyme MB activity in serum using immunological inhibition of creatine kinase M subunit activity. Activity kinetics and diagnostic significance in myocardial infarction.

This is a new method for the determination of creatine kinase isoenzyme MB activity in serum. The method uses direct activity measurement of creatine kinase B subunit activity after blocking of CK-M subunit activity by inhibiting antibodies. The test takes no longer than 15 min. The method yields an intra-serial C.V. of 2.0-12.9%, and a C.V. from day to day of 5.5%. The detection limit is 3.4 U/l creatine kinase MB. In the 95 cases with proven myocardial infarction several types of creatine kinase MB activity kinetics could be determined. The percentage of creatine kinase MB of peak CK-total is 6-25%, with a mean of 11.1%. The amount of creatine kinase MB with respect to total CK activity after reinfarction is higher than the amount after initial infarction.     

Prise en charge des entorses externes de cheville : étude clinique préliminaire sur l’efficacité du dispositif Myolux™

Ankle sprains are the most common injury of the musculoskeletal system and are associated with significant societal and economic impacts. It has been proven that classical therapeutic strategies may not be effective in preventing recurrent injuries: the recurrence rates reported in the literature can reach 73%. In order to provide an effective rehabilitation solution, a destabilizing orthosis was developed. This device is equipped with a mechanical articulator reproducing the subtalar mechanics and placed under the heel. In this paper, we present the main results of a preliminary clinical study conducted between 2004 and 2007. All subjects included in this study were treated with the abovementioned orthosis during 10 rehabilitation sessions of 30 minutes each. Data show a relatively low recurrence rate of 12% for the overall population. Moreover, it's of primary importance to note that this satisfactory ratio is largely reduced (3% of recurrence rate) for the 29 patients who performed one training session per month after the 10th initial rehabilitation sessions. Hence, the destabilizing orthosis appears to be an effective solution to prevent recurrent ankle sprains. However, joint protection requires long-term and regular training sessions. This result has motivated the development of a similar device allowing patients to perform training sessions at home. Finally, data obtained in this study are promising awaiting the final results of the comparative, multicentric and independent clinical trials currently managed by the Hospices Civils de Lyon.     

俯卧位通气对高海拔地区肺复张治疗无效急性呼吸窘迫综合征患者氧合的影响

目的 探讨俯卧位通气对高海拔地区肺复张术(RM)治疗无效急性呼吸窘迫综合征(ARDS)患者的治疗作用.方法 从海拔2260m的地区医院筛选RM治疗无效的41例ARDS患者[平均氧合指数( PaO2/FiO2)较RM前升高＜20％视为RM无效],依不同病因分为肺内源性ARDS组(ARDSp组)和肺外源性ARDS组(ARDSexp组),每组再按信封法随机分为俯卧位组和仰卧位组,即ARDSp俯卧位组(11例)、ARDSp仰卧位组(9例)、ARDSexp俯卧位组(10例)、ARDSexp仰卧位组(11例).在通气前及通气1、2、3、4h监测动脉血氧分压( PaO2)、PaO2/FiO2、静态顺应性(Cst)、气道阻力(Raw)的变化.结果 通气lh时,ARDSexp俯卧位组PaO2/FiO2( mm Hg,l mm Hg=0.133 kPa)即较通气前显著升高(157.4±40.6比129.3±48.7,P＜0.05),并随通气时间延长呈持续增高趋势,4h达峰值(219.1 ±41.1);且ARDSexp俯卧位组通气3h内PaO2/FiO2较其他3组显著增高,另3组间则差异无统计学意义.ARDSp俯卧位组、ARDSexp俯卧位组通气4h时PaO2/FiO2均较相应仰卧位组显著增高(208.8±39.7比127.4±47.1,219.1±41.1比124.9±50.8,均P＜0.05).4组通气前后Cst无显著改变,各组间差异也无统计学意义.ARDSp俯卧位组通气4h时Raw(cmH2O·L-1·s-1)较通气前显著降低(6.8±1.7比10.7±1.8,P＜0.05),且明显低于其他3组;其他3组各时间点Raw组内及组间比较差异均无统计学意义.结论 俯卧位通气作为ARDS机械通气重要策略之一,可以改善RM无效高原ARDS患者的氧合,为抢救患者赢得宝贵的时间.     

Digital imaging among medical facilities

The Department of Veterans Affairs (VA) in the USA operates a network of 172 medical centres which all utilize a hospital information system (HIS) which has been developed and is currently maintained by the VA. During the past several years, an image management and communication module has been developed, installed and clinically utilized at the Washington DC and Maryland VA Medical Centres. This image management and communication system, referred to as the decentralized hospital computer program (DHCP) imaging system, is fully integrated with a commercial picture archiving and communication system (PACS). The system is utilized to capture, archive, and display all images generated within the hospital including radiology, nuclear medicine, pathology, endoscopy, bronchoscopy, and dermatology, intraoperative photographs, ECG data, and a limited number of paper documents. The ultimate goal of the project is to have all patient text and image data available at any clinical workstation to any authorized user anywhere within the network of medical centres. Clinical requirements for an imaging workstation include ease of use, rapid and reliable access to the complete set of patient information, and images which are of acceptable quality to meet the requirements of the user and the subspecialty. Patient confidentiality and data security must be safeguarded at all times. Integration of the images with the remainder of the patient's database was found to be critical to the success of the project. The experience at the Washington and Maryland facilities suggests that an imaging system that is successfully integrated with a hospital information system can provide substantial clinical and economic benefits both within and among medical centres. Clinical acceptance and utilization of the system has been excellent, particularly in diagnostic radiology where DHCP Imaging has been interfaced to a commercial PAC system. Based upon this initial experience, the VA has begun to deploy the system throughout its large network of medical centres.     

Myocardial elastography at both high temporal and spatial resolution for the detection of infarcts

Myocardial elastography is a novel method for noninvasively assessing regional myocardial function, with the advantages of high spatial and temporal resolution and high signal-to-noise ratio (SNR). In this paper, in-vivo experiments were performed in anesthetized normal and infarcted mice (one day after left anterior descending coronary artery [LAD] ligation) using a high-resolution (30 MHz) ultrasound system (Vevo 770, VisualSonics Inc., Toronto, ON, Canada). Radiofrequency (RF) signals of the left ventricle (LV) in longitudinal (long-axis) view and the associated electrocardiogram (ECG) were simultaneously acquired. Using a retrospective ECG gating technique, 2-D full field-of-view RF frames were acquired at an extremely high frame rate (8 kHz) that resulted in high-quality incremental displacement and strain estimation of the myocardium. The incremental results were further accumulated to obtain the cumulative displacements and strains. Two-dimensional and M-mode displacement images and strain images (elastograms), as well as displacement and strain profiles as a function of time, were compared between normal and infarcted mice. Incremental results clearly depicted cardiac events including LV contraction, LV relaxation and isovolumetric phases in both normal and infarcted mice, and also evidently indicated reduced motion and deformation in the infarcted myocardium. The elastograms indicated that the infarcted regions underwent thinning during systole rather than thickening, as in the normal case. The cumulative elastograms were found to have higher elastographic SNR (SNR(e)) than the incremental elastograms (e.g., 10.6 vs. 4.7 in a normal myocardium, and 6.0 vs. 2.4 in an infarcted myocardium). Finally, preliminary statistical results from nine normal (m = 9) and seven infarcted (n = 7) mice indicated the capability of the cumulative strain in differentiating infracted from normal myocardia. In conclusion, myocardial elastography could provide regional strain information at simultaneously high temporal (>/=0.125 ms) and spatial ( approximately 55 microm) resolution as well as high precision ( approximately 0.05 microm displacement). This technique was thus capable of accurately characterizing normal myocardial function throughout an entire cardiac cycle, at the same high resolution, and detecting and localizing myocardial infarction in vivo.