正常人左室收缩功能的超声三维斑点追踪研究

目的运用三维斑点追踪成像技术(3D-STI)评价正常人左室短轴及长轴心肌应变特征,探讨其对正常人左室收缩功能的评判价值。方法健康志愿者45名,采集标准左室长轴心尖四腔、三腔切面左室全容积图像进行在线分析,自动计算左室舒张末期容积(LVEDV)、左室收缩末期容积(LVESV)、左室射血分数(LVEF)、左室短轴径向各水平收缩期峰值及平均应变、左室短轴环向各水平收缩期峰值及平均应变、左室长轴纵向各水平收缩期峰值及平均应变,分析各应变指标变化情况。结果正常人左室短轴径向各节段收缩期峰值及平均应变,基底水平较中间段水平增大(P<0.05),中间段水平较心尖水平增大(P<0.05),基底水平较心尖水平增大(P<0.01)。正常人左室短轴环向各节段收缩期峰值及平均应变,心尖水平较中间段水平增大(P<0.05),中间段水平较基底水平增大(P<0.05),心尖水平较基底水平增大(P<0.01)。正常人左室长轴纵向收缩期峰值及平均应变,心尖水平较中间段水平增大(P<0.05),中间段水平较基底水平增大(P<0.05),心尖水平较基底水平增大(P<0.01)。结论 3D-STI可无创、客观评价正常人在不同水平和不同节段径向、环向、纵向心肌应变,为定量评价正常人左室收缩功能提供了一种新的思路。     

An Angular Compounding Technique Using Displacement Projection for Noninvasive Ultrasound Strain Imaging of Vessel Cross-Sections

Strain is considered to be a useful indicator of atherosclerotic plaque vulnerability. This study introduces an alternative for a recently introduced strain imaging method that combined beam steered ultrasound acquisitions to construct radial strain images of transverse cross-sections of superficial arteries. In that study, axial strains were projected in the radial direction. Using the alternative method introduced in this study, axial displacements are projected radially, followed by a least squares estimation of radial strains. This enables the use of a larger projection angle. Consequently, fewer acquisitions at smaller beam steering angles are required to construct radial strain images. Simulated and experimentally obtained radio-frequency data of radially expanding vessel phantoms were used to compare the two methods. Using only three beam steering angles (–30°, 0° and 30°), the new method outperformed the older method that used seven different angles and up to 45° of beam steering: the root mean squared error was reduced by 38% and the elastographic signal- and contrast-to-noise ratios increased by 1.8 dB and 4.9 dB, respectively. The new method was also superior for homogeneous and heterogeneous phantoms with eccentric lumens. To conclude, an improved noninvasive method was developed for radial strain imaging in transverse cross-sections of superficial arteries. (E-mail: r.hansen@cukz.umcn.nl)     

心肌应变与应变率在心血管疾病中的应用

近年来我国心血管疾病的发病率以及死亡率逐年增多,现已成为我国最高致死性疾病之一,对此类患者局部心肌功能的评价对其疾病的诊断、治疗及预后具有重要意义,因此在临床工作中,迫切需要一个能对局部心肌功能做出客观、定量评价的技术。心肌应变(Strain,S)及应变率(StrainSRate,SR)可以测量局部心肌组织发生的极小形变,从而更加准确的评价局部心肌功能及室壁运动。本文将就近年来心肌应变与应变率在心血管疾病中的应用情况进行综述。     

急性肺血栓栓塞症患者右室长轴应变及应变率变化的初步研究

目的：观察急性肺血栓栓塞症（APTE）患者右室压力负荷增加后右室长轴应变、应变率变化特点,并寻找可能判断右心功能不全的有效参数。方法：采集21例APTE患者及30例健康自愿者心尖四腔切面的二维图像,在组织速度显像（TV I）模式下应用应变、应变率成像技术测量右室游离壁及室间隔的基底段、中间段、心尖段心内膜下心肌收缩期峰值应变、应变率,进行分析研究。结果：APTE患者肺动脉压中度增高后,右室游离壁及室间隔基底段、中间段收缩期应变和应变率代偿性增强,左室收缩功能变化不大,而舒张功能轻度减低;APTE患者肺动脉压重度增高后,右室各节段收缩期应变和应变率较对照组均明显减小,以右室游离壁中间段变化最为明显,同时左室、右室收缩功能均减低。以右室游离壁中间段作为代表节段,以收缩期应变小于-15%,应变率小于-1.2s^- 1作为APTE时右心功能可能失代偿的参考指标。结论：应变、应变率技术是评价急性肺血栓栓塞症患者右室收缩功能变化的一种敏感、有效的方法。     

The 7.5-kb common plasmid is unrelated to the drug susceptibility of Chlamydia trachomatis

Using a new plaque cloning technique, we obtained unique Chlamydia trachomatis strains, which were confirmed to be free of the 7.5-kb common plasmid and glycogen in inclusions. The inclusions in plasmid-free and glycogen-negative strains were characterized by a target-like bull's eye morphology that appeared with the formation of a central translucent area that began to be seen clearly at 30 h postinoculation. The clear zone was composed of gel materials originating from reticulate bodies (RBs) that were abnormally large in size and irregular in shape, although one could not differentiate the aberrant RBs from normal RBs at early stages of development. The in-vitro susceptibility of these strains to various chemotherapeutic antibiotics was tested by comparison with their parent strains possessing the common plasmid. No difference was detected for any of the antibiotics tested, indicating that the 7.5-kb common plasmid is unrelated to the drug susceptibility of C. trachomatis. Received: August 7, 2000 / Accepted: December 11, 2000     

Direct mean strain estimation for elastography using nearest-neighbor weighted least-squares approach in the frequency domain

Ultrasound elastography is emerging with enormous potential as a medical imaging modality for effective discrimination of pathological changes in soft tissue. It maps the tissue elasticity or strain due to a mechanical deformation applied to it. The strain image most often calculated from the derivative of the local displacement field is highly noisy because of the de-correlation effect mainly due to unstable free-hand scanning and/or irregular tissue motion; consequently, improving the SNR of the strain image is still a challenging problem in this area. In this paper, a novel approach using the nearest-neighbor weighted least-squares is presented for direct estimation of the ‘mean’ axial strain for high quality strain imaging. Like other time/frequency domain reported schemes, the proposed method exploits the fact that the post-compression rf echo signal is a time-scaled and shifted replica of the pre-compression rf echo signal. However, the elegance of our technique is that it directly computes the mean strain without explicitly using any post filter and/or previous local displacement/strain estimates as is usually done in the conventional approaches. It is implemented in the short-time Fourier transform domain through a nearest-neighbor weighted least-squares-based Fourier spectrum equalization technique. As the local tissue strain is expected to maintain continuity with its neighbors, we show here that the mean strain at the interrogative window can be directly computed from the common stretching factor that minimizes a cost function derived from the exponentially weighted windowed pre- and post-compression rf echo segments in both the lateral and axial directions. The performance of our algorithm is verified for up to 8% applied strain using simulation and experimental phantom data and the results reveal that the SNR of the strain image can be significantly improved compared to other reported algorithms in the literature. The efficacy of the algorithm is also tested with in vivo breast data known to have malignant or benign masses from histology.     

Performance of Two Dimensional Displacement and Strain Estimation Techniques Using a Phased Array Transducer

The goal of this study was to investigate the applicability of conventional 2-D displacement and strain imaging techniques to phased array radiofrequency (RF) data. Furthermore, the possible advantages of aligning and stretching techniques for the reduction of decorrelation artefacts was examined. Data from both realistic simulations and phantoms were used in this study. Recently, the used processing concepts were successfully applied to linear array data. However, their applicability to sector scan data is not trivial because of the polar grid. Homogeneous and inhomogeneous tissue phantoms were simulated at a range of strains (0 to 5%) using Field II^©. The inhomogeneous phantom, a commonly used tumor/lesion model, was also constructed using gelatin/agar solutions. A coarse-to-fine displacement algorithm was applied, using aligning and stretching to enhance re-correlation. Vertical and horizontal strains were reconstructed from the axial and lateral displacements. Results revealed that the error on displacement estimates was lower when using 2-D data windows rather than 1-D windows. For regions at large depths and large insonification angles, the allowed lateral window size was limited. Still, 1-D windows resulted in larger errors. The re-correlation techniques resulted in a significant increase in the elastographic signal-to-noise ratio (SNRe) and elastographic contrast-to-noise ratio (CNRe) of the vertical and horizontal strain components. An increase of the SNRe of 5–20 dB was observed over a range of strains (0.5 to 5.0%). In the inhomogeneous phantom, a vertical SNRe of 27.7 dB and a horizontal SNRe of 16.7 dB were measured in the background. The vertical and horizontal CNRe were 35 dB and 23.1 dB, respectively. For the experimental data, lower SNRe (vertical: 19.1 dB; horizontal: 11.4 dB) and CNRe (vertical: 33.3 dB; horizontal: 12.5 dB) were found. In conclusion, 2-D window matching of sector scan data is feasible and outperforms 1-D window matching. Furthermore, the use of re-correlation techniques enhances both precision and contrast of strain images. (E-mail: r.lopata@cukz.umcn.nl)     

2007年中国CHINET细菌耐药性监测

目的了解国内主要地区医院临床分离菌对常用抗菌药物的耐药性。方法国内主要地区12所教学医院（10所综合性医院，2所儿童医院）临床分离菌采用K—B法按统一方案进行抗菌药物敏感试验。按CLSI 2007版判断结果。结果2007年1—12月收集各医院临床分离株共36001株，其中革兰阳性菌占34．3％，革兰阴性菌占65．7％。金葡菌和凝固酶阴性葡萄球菌中甲氧西林耐药株平均为58％和77％。大肠埃希菌、克雷伯菌属（肺炎克雷伯菌和产酸克雷伯菌）中产ESBLs株平均为55％和45％。葡萄球菌属中甲氧西林耐药株对8内酰胺类抗生素和其他抗菌药的耐药率显著高于甲氧西林敏感株，但仍有约60％80％的菌株对磷霉素、复方磺胺甲嗯唑或利福平敏感，未发现对万古霉素、替考拉宁和利奈唑胺耐药株。肠球菌属中粪肠球菌对多数药物的耐药率低于屎肠球菌，但后者对氯霉素的耐药率仅6％。粪肠球菌对呋喃妥因和磷霉素的耐药率均低于10％。两者中均出现少数对万古霉素和替考拉宁耐药株，经PCR检测27株VRE均系VanA型耐药。大肠埃希菌、克雷伯菌属（肺炎克雷伯菌和产酸克雷伯菌）、奇异变形杆菌中产ESBLs株对抗菌药的耐药率均比非产ESBLs株高。流感嗜血杆菌和卡他莫拉菌的产酶率分别为27，4％和96．1％。肺炎链球菌儿童分离株中青霉素不敏感株显著高于成人分离株，两者分别为88．5％和26．4％。肠杆菌科细菌对碳青霉烯类仍高度敏感，总耐药率〈1％，其次为阿米卡星、头孢哌酮一舒巴坦。铜绿假单胞菌对亚胺培南、美罗培南耐药率分别为36％和28．5％，不动杆菌属对两者的耐药率分别为40％和35％。米诺环素对嗜麦芽窄食单胞菌、伯克霍尔德菌有良好活性，两者的耐药率均低于5％，值得注意。不发酵糖革兰阴性杆菌对抗菌药物的耐药率均显著高于肠杆菌科?     

Fall armyworm FR sequences map to sex chromosomes and their distribution in the wild indicate limitations in interstrain mating

The fall armyworm, Spodoptera frugiperda, consists of two host strains (rice and corn) that differ in developmental, physiological and behavioural characteristics. However, because the strains are morphologically indistinguishable the investigation of strain-specific behaviour, particularly in the wild, is very difficult. This has spurred the isolation of diagnostic molecular markers. FR sequences are tandem-repeat genetic elements found in large clusters only in the rice strain. To facilitate their use as a strain marker we genetically mapped FR clusters and found they localized to the sex chromosomes. This represents one of the first examples of chromosome mapping in fall armyworm. The FR sequence and a strain-specific mitochondrial marker were then used to examine the distribution of different marker combinations in field specimens. These studies identified significant barriers to interstrain mating in the wild, specifically that corn strain females rarely, if ever, mate with rice strain males. The data also suggest that only a genetically distinct subset of the overwintering rice strain population in Florida annually migrate to Georgia. These studies demonstrate that the availability of genetically characterized molecular markers for strain identity makes possible studies on fall armyworm biology in the wild previously considered unfeasible.     

P REHOSPITAL A IRWAY M ANAGEMENT WITH THE L ARYNGEAL M ASK A IRWAY IN P OLYTRAUMATIZED P ATIENTS

Abstract

Background. Thermal protective clothing (TPC) worn by firefighters provides considerable protection from the external environment during structural fire suppression. However, TPC is associated with physiologic derangements that may have adverse cardiovascular consequences. These derangements should be treated during on-scene rehabilitation periods. Objective. To examine heart rate and core temperature responses during the application of four active cooling devices, currently being marketed to the fire service for on-scene rehabilitation, and compare them with passive cooling in a moderate temperature (approximately 24°C) and with an infusion of cold (4°C) saline. Methods. Subjects exercised while they were wearing TPC in a heated room. Following an initial exercise period (bout 1), the subjects exited the room, removed the TPC, and for 20 minutes cooled passively at room temperature, received an infusion of cold normal saline, or were cooled by one of four devices (fan, forearm immersion in water, hand cooling, or water-perfused cooling vest). After cooling, the subjects donned the TPC and entered the heated room for another 50-minute exercise period (bout 2). Results. The subjects were not able to fully recover core temperature during a 20-minute rehabilitation period when provided rehydration and the opportunity to completely remove the TPC. Exercise durations were shorter during bout 2 when compared with bout 1 but did not differ by cooling intervention. The overall magnitudes and rates of cooling and heart rate recovery did not differ by intervention. Conclusions. No clear advantage was identified when active cooling devices and cold intravenous saline were compared with passive cooling in a moderate temperature after treadmill exercise in TPC.     

铜绿假单胞菌抗药基因检测及其对消毒剂抗性研究

目的研究临床分离的铜绿假单胞菌携带的抗药基因情况及其与消毒剂的抗性关系和水平。方法采用PCR方法和肉汤稀释法分别检测临床分离铜绿假单胞菌qacE△1-SulI基因和对消毒剂抗性变化,并与铜绿假单胞菌标准菌株进行了平行比较。结果临床分离的6株铜绿假单胞菌中,有5株检出qacE△1-SulI基因阳性,抗药基因携带率达到83%以上。醋酸氯己定对6株临床分离铜绿假单胞菌的MIC值为7.8mg/L,与标准菌株相同;对氯间二甲苯酚对其中1株临床分离株的MIC高于标准菌株,但有2株低于标准株;苯扎溴铵对6株临床分离的铜绿假单胞MIC均低于标准株;聚维酮碘对5株qacE△1-SulI基因阳性菌株的MIC值与标准菌株相同,但抗药基因阴性菌株的MIC值低于标准株。结论临床分离的铜绿假单胞菌多数携带qacE△1-SulI基因,该抗药基因的携带与其对消毒剂的抗性有一定的相关性。     

四种消毒剂对两种临床感染菌的杀灭效果

目的观察4种临床常用消毒剂对医院感染白色念珠菌、耐甲氧西林金黄色葡萄球菌的杀灭效果,以了解其对消毒剂抗力变化情况。方法用悬液定量杀菌试验方法,对以碘、醛、有效氯和氯己定等4种杀菌成分的消毒剂杀灭两种医院感染菌的效果进行了实验室观察。结果以含有效碘5000mg/L的碘伏作用1.5min,20g/L戊二醛作用3min,有效氯1000mg/L的三氯异氰尿酸泡腾片消毒液作用1min,含40g/L葡萄糖酸氯己定溶液作用2min,对白色念珠菌和金黄色葡萄球菌标准株杀灭率均为100%。以含有效碘50mg/L碘伏、125mg/L戊二醛、有效氯250mg/L三氯异氰尿酸泡腾片、2500mg/L葡萄糖酸氯己定溶液,均作用10min,对白色念珠菌、耐甲氧西林金黄色葡萄球菌医院感染菌株和标准株的杀灭率均达到100%。结论临床常用的4种消毒剂对白色念珠菌和耐甲氧西林金黄色葡萄球菌医院感染菌株杀灭效果与标准株没有明显差别。