Four-gated transcranial Doppler ultrasound in the detection of circulating microemboli.

OBJECTIVE: Embolus detection by transcranial Doppler ultrasound is very time consuming and semi-automated detection is mandatory. The device studied, a TC4040, Nicolet-EME, uses the four-gate technique and allows for audiovisual off-line verification of the recorded events. METHODS: Twenty controls, 10 patients with mechanical prosthetic heart valves and 12 patients with occlusive carotid artery disease were investigated by transcranial colour-coded duplex sonography and, subsequently, underwent a 1-h unilateral embolus detection from the middle cerebral artery using four-gate TCD. We investigated the Doppler spectrum background, microembolic signals (MES) and artefacts produced. A detection threshold of 5 dB or more was defined taking into account natural fluctuations of the Doppler spectrum. RESULTS: Sensitivity of the software was 91.9% and observer-software agreement on MES was 7.8% in the valve patients, and 77.7% and 7.5% in the carotid artery disease patients, respectively. Weaker MES were more likely not to be detected in all four channels. The artefact signal rejection rate was 62%. MES produced either positive or zero time delays in adjacent channels. Artefact signals produced either no delay, or a positive or a negative time delay. Duration of MES ranged from 1-88 ms. CONCLUSIONS: Besides refined recognition of MES using the time delay, four gates give faint MES no less than four opportunities to overcome the detection threshold. With this device's satisfying sensitivity, regions of interest in a 1-h recording can audiovisually be evaluated off-line in a few minutes by an investigator.     

Microembolic signal description: a reappraisal based on a customized digital postprocessing system

The high variability in presence and signature of microembolic signals (MES), detected with transcranial Doppler sonography (TCD) in the middle cerebral artery (MCA), cannot be explained with the currently available published data. We applied customized postprocessing on the radiofrequency (RF) signal of a standard TCD system. The spatial resolution was on the order of 2 mm, depending only on the length of the ultrasound (US) burst emitted. The amplitude of clutter-filtered RF signals was color-coded and plotted as a function of time and depth (range 30 mm). Additionally, 128 point fast Fourier transforms (FFTs) (50% temporal overlap) were calculated, visualizing both the background Doppler spectrum and the MES. We evaluated 122 gaseous MES from two patients during cardiac surgery and 52 particulate MES from four patients after carotid endarterectomy. Both MES categories showed comparable properties: they appeared in the RF amplitude plot as rather straight lines of increased intensity, indicating that the velocity remained approximately the same while they passed the US beam. The velocity calculated from the amplitude plot never exceeded that of the background Doppler spectrum. Various "MES patterns" could be identified with respect to the depth range at which the MES were visible. A quarter of the gaseous MES changed their direction at a specific depth, suggesting that the MES entered a branch (e.g., an M2 artery or the anterior cerebral artery). In the FFT analysis, these MES contained both positive and negative frequencies. It is concluded that MES show consistent signature patterns in the amplitude-time plots and that the previously reported variability of MES appearance in conventional Doppler systems is an artefact caused by relatively large signal amplitudes and sample volumes.     

Differentiation between true microembolic signals and artefacts using an arbitrary sample volume

We evaluated a new discrimination technique between microemboli (MES) and artefact signals. Monitoring was performed over the middle cerebral artery (55 mm) and the brain parenchyma (29 mm). Intensity changes were expressed as percent of change compared to the value measured in the proximal depth. The cut-off value providing the highest sensitivity and specificity in the differentiation was evaluated using 250 MES and 250 artefact signals, and subsequently analysed in the first part of the study. Intensity values derived from the distal depth were subsequently evaluated in 10 patients undergoing cardiac surgery and 45 patients with potential arterial or cardioembolic source. Intensity changes of 87% (84%-90%) and -58% (-71%-(-48%)) were measured in the initial 500 signals for MES and artefact signals, respectively. The best intensity cut-off value was calculated at 27%. This value was subsequently applied to a total of 1858 MES and 1958 artefacts, resulting to sensitivity and specificity of 96% and 98%, respectively. The proposed technique provided adequate results, warranting further evaluation.     

双门深TCD检测脑动脉微栓子信号的敏感性和特异性

目的：研究双门深ＴＣＤ检测微栓子信号（ＭＥＳ）的敏感性和特异性。方法：采用双门深ＴＣＤ对２６例人工心瓣膜患者进行脑动脉微栓子检测,并与在线状态下有经验医师的人工判断（作为黄金标准）相比较。结果：双门深ＴＣＤ检测ＭＥＳ的敏感性为５９．６％,特异性为６４．４％。结论：双门深ＴＣＤ为识别、检测ＭＥＳ提供了新方法,但在线状态下的人工判断仍然是必需的。ＭＥＳ相对强度阈值对双门深ＴＣＤ检测ＭＥＳ敏感性和特异性的影响值得进一步研究。     

Common Carotid Artery Duplex for the Bubble Test to Detect Right-to-Left Shunt

We prospectively compared the bubble test with agitated saline for right-to-left shunt using transcranial Doppler (TCD) of the right middle cerebral artery and second harmonic imaging duplex of the right common carotid artery (CCA) in 100 consecutive patients. Microembolic signals (MES) were counted offline. MES were classified into 6 classes: absent (class 0), 1–10 MES (class 1), 11–20 MES (class 2), 21–30 MES (class 3), 31–50 MES (class 4) and >50 MES or “curtain effect” (class 5). For TCD, classes 2–5 combined (i.e., “large” shunts), the sensitivity of duplex with the Valsalva maneuver was 95.3%, the specificity was 100%, the positive predictive 100%, the negative predictive value 96.6% and accuracy 98.0%. Second harmonic imaging duplex of the CCA may substitute TCD for the bubble test when an adequate cranial bone window is not available. This technique may also greatly increase the number of facilities where the bubble test can be carried out. However, tests with few or no MES need to be confirmed by TCD or transesophageal echocardiography. (E-mail: irosnec@live.it)     

Reducing the gradient artefact in simultaneous EEG-fMRI by adjusting the subject's axial position

Large artefacts that compromise EEG data quality are generated when electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are carried out concurrently. The gradient artefact produced by the time-varying magnetic field gradients is the largest of these artefacts. Although average artefact correction (AAS) and related techniques can remove the majority of this artefact, the need to avoid amplifier saturation necessitates the use of a large dynamic range and strong low-pass filtering in EEG recording. Any intrinsic reduction in the gradient artefact amplitude would allow data with a higher bandwidth to be acquired without amplifier saturation, thus increasing the frequency range of neuronal activity that can be investigated using combined EEG-fMRI. Furthermore, gradient artefact correction methods assume a constant artefact morphology over time, so their performance is compromised by subject movement. Since the resulting, residual gradient artefacts can easily swamp signals from brain activity, any reduction in their amplitude would be highly advantageous for simultaneous EEG-fMRI studies. The aim of this work was to investigate whether adjustment of the subject's axial position in the MRI scanner can reduce the amplitude of the induced gradient artefact, before and after artefact correction using AAS. The variation in gradient artefact amplitude as a function of the subject's axial position was first investigated in six subjects by applying gradient pulses along the three Cartesian axes. The results of this study showed that a significant reduction in the gradient artefact magnitude can be achieved by shifting the subject axially by 4 cm towards the feet relative to the standard subject position (nasion at iso-centre). In a further study, the 4-cm shift was shown to produce a 40% reduction in the RMS amplitude (and a 31% reduction in the range) of the gradient artefact generated during the execution of a standard multi-slice, EPI sequence. By picking out signals occurring at harmonics of the slice acquisition frequency, it was also shown that the 4-cm shift led to a 36% reduction in the residual gradient artefact after AAS. Functional and anatomical MR data quality is not affected by the 4-cm shift, as the head remains in the homogeneous region of the static magnet field and gradients.     

Neurological and neuropsychological examination and outcome after use of an intra-aortic filter device during cardiac surgery

Cerebral embolization of particles after cardiac surgery is frequently associated with neurological deficits. Aortic crossclamp manipulation seems to be the most significant cause of emboli release during cardiac surgery. The goal of this study was to demonstrate whether the use of an intra-aortic filter device has an effect on the magnet resonance imaging (MRI) and functional neurological outcome. Twenty-four patients undergoing cardiosurgical procedures using cardiopulmonary bypass (CPB) were selected: coronary artery bypass graft (CABG) surgery (n = 17), aortic valve replacement (AVR) surgery (n = 4) or combined procedures (n = 3). Patients were evaluated by diffusion weighted MRI of the brain, neurological examination and neuropsychological assessment regarding alertness as well as divided and selective attention before and five to seven days after surgery. The patients were divided into two groups. In group I, 12 patients received a filter through a modified 24 F arterial cannula immediately before the aortic crossclamp was released. Filters remained in the aorta until CPB was discontinued. Intraoperatively, bilateral middle cerebral artery transcranial Doppler (TCD) was monitored at baseline, at the beginning of CPB, at a timepoint when the aorta was crossclamped, when the filter was inserted and while the crossclamp was switched to partial clamping until the CPB was discontinued. TCD was used for detection of microembolic signals (MES). The captured material in the filter was examined histologically. Twelve patients served as controls without aortic filtration (group II). The MRI of the brain did not show any diffusion alterations in either group before or after surgery. No patient developed a focal neurological deficit or stroke. Intraoperative quantitative MES detection revealed a four to tenfold increase in patients of group I compared with group II (5-6 versus 0.5-1 MES/min) during the filter dwell time. There was no consistent pattern regarding the neurobehavioural sequelae. Filters showed arteriosclerotic debris in 75% of the patients. The use of the intra-aortic filter device did not show a positive effect on neurological, neuroradiographical and neuropsychological outcomes. The increase of the MES rate in group I patients may be due to microbubbles generated as microcavitations by the filter or the aortic filter cannula. The intra-aortic filter was able to capture atheromatous material in 75% of the patients.     

Ultrasound measurements of the saphenous vein in the pediatric emergency department population with comparison to i.v. catheter size

Background

Saphenous vein cutdown is a rare venous access procedure. Ultrasound (US) can assist with many vascular access procedures.

Objectives

Our objective was to identify the saphenous veins (SVs) using US in pediatric emergency department (ED) patients, and to determine if the SV size allows for potential cannulation by different standard-size intravenous (i.v.) catheters.

Methods

This study was a prospective, observational convenience sample of 60 pediatric patients at an urban, regional referral pediatric ED. Inclusion criteria were children ages 1 through 12 years categorized into four age groups: 1–<2, 2–4, 5–7, and 8–12 years, with informed consent and assent. Investigators performed US examination using a 10-MHz multi-frequency transducer to identify the SV on both legs and measure the SV in short-axis view. The US measurements were then used to calculate the SV areas. Diameters of typical pediatric gauge (G) catheters (24G, 22G, 20G, 18G) were used to calculate catheter areas.

Results

Sixty patients were enrolled, with five SVs unable to be measured in 4 patients (1 patient with both SVs). For the remaining 115 (96%) SVs available for further analysis, the median age was 4 years (interquartile range [IQR] 2) and median weight was 22.7 kg (IQR 14.5). Mean area (mm²) of the right SV was 2.85 ± 1.9 and for the left SV, 2.88 ± 1.8. For our study group, the compatibility rates of different size i.v. catheters to fit the measured SV areas were as follows: 24G = 100%, 22G = 100%, 20G = 97.3%, and 18G = 86.1%.

Conclusions

US can localize the SV in pediatric ED patients. US size of the SV in various pediatric age ranges suggests that the SV may be a potential US venous access site with multiple-size i.v. catheters up to 18G.     

经颅多普勒超声微栓子检测在颈动脉支架成形术中的应用

目的 应用经颅多普勒超声（TCD）动态观察脑保护滤网下颈动脉支架成形术中各操作阶段所产生的微栓子信号（MES）数量。 方法 对11例在脑保护滤网下颈动脉支架成形术患者术中采用TCD进行MES监测。将整个操作过程分为5个阶段，分别观察各操作阶段中患侧大脑中动脉的MES数量。 结果 11例患者术中各操作阶段均可产生MES。其中预扩、支架置入和后扩是栓子最易脱落的3个阶段，占MES总数量的68.7%。 结论 采用TCD可以有效地监测颈动脉支架成形术中各个阶段的MES数量，指导手术安全进行。     

微栓子监测对抗血栓药物疗效的评价

目的:探讨微栓子监测评价缺血性卒中患者抗凝或抗血小板聚集药物的治疗效果。方法:75例发病1周内经CT或MRI证实的缺血性卒中患者入选本试验组。常规TCD检查后,进入TCD 8.0微栓子监测软件,取双侧大脑中动脉(MCA)作监测血管,监测时间为40min。对微栓子监测阳性的患者,在常规治疗脑梗死药物的基础上加用抗凝药物(速碧林)或抗血小板聚集药物(力抗栓)治疗,分别在治疗前及治疗后第3、5、7、10天进行微栓子监测,观察药物治疗对微栓子的影响。结果:微栓子监测14例(18.7%)阳性;抗凝组(7例)和抗血小板聚集组(7例)治疗后第3、5、7、10天,MES明显低于治疗前(P<0.05);治疗后第5天,抗凝组MES的下降率高于抗血小板聚集组(P<0.05)。结论:抗凝或抗血小板聚集药物可以抑制MES的产生,而抗凝药物降低微栓子的作用比抗血小板聚集药物起效快;MES监测可作为评价抗凝或抗血小板聚集药物治疗是否有效的一项检测指标。     

Detection of ventricular fibrillation in the presence of cardiopulmonary resuscitation artefacts

Providing cardiopulmonary resuscitation (CPR) to a patient in cardiac arrest introduces artefacts into the electrocardiogram (ECG), corrupting the diagnosis of the underlying heart rhythm. CPR must therefore be discontinued for reliable shock advice analysis by an automated external defibrillator (AED). Detection of ventricular fibrillation (VF) during CPR would enable CPR to continue during AED rhythm analysis, thereby increasing the likelihood of resuscitation success. This study presents a new adaptive filtering method to clean the ECG. The approach consists of a filter that adapts its characteristics to the spectral content of the signal exclusively using the surface ECG that commercial AEDs capture through standard patches. A set of 200 VF and 25 CPR artefact samples collected from real out-of-hospital interventions were used to test the method. The performance of a shock advice algorithm was evaluated before and after artefact removal. CPR artefacts were added to the ECG signals and four degrees of corruption were tested. Mean sensitivities of 97.83%, 98.27%, 98.32% and 98.02% were achieved, producing sensitivity increases of 28.44%, 49.75%, 59.10% and 64.25%, respectively, sufficient for ECG analysis during CPR. Although satisfactory and encouraging sensitivity values have been obtained, further clinical and experimental investigation is required in order to integrate this type of artefact suppressing algorithm in current AEDs.     

Wavelet denoising of displacement estimates in elastography

Wavelet shrinkage denoising of the displacement estimates to reduce noise artefacts, especially at high overlaps in elastography, is presented in this paper. Correlated errors in the displacement estimates increase dramatically with an increase in the overlap between the data segments. These increased correlated errors (due to the increased correlation or similarity between consecutive displacement estimates) generate the so-called "worm" artefact in elastography. However, increases in overlap on the order of 90% or higher are essential to improve axial resolution in elastography. The use of wavelet denoising significantly reduces errors in the displacement estimates, thereby reducing the worm artefacts, without compromising on edge (high-frequency or detail) information in the elastogram. Wavelet denoising is a term used to characterize noise rejection by thresholding the wavelet coefficients. Worm artefacts can also be reduced using a low-pass filter; however, low-pass filtering of the displacement estimates does not preserve local information such as abrupt change in slopes, causing the smoothing of edges in the elastograms. Simulation results using the analytic 2-D model of a single inclusion phantom illustrate that wavelet denoising produces elastograms with the closest correspondence to the ideal mechanical strain image. Wavelet denoising applied to experimental data obtained from an in vitro thermal lesion phantom generated using radiofrequency (RF) ablation also illustrates the improvement in the elastogram noise characteristics.     

Automatic artefact removal in a self-paced hybrid brain- computer interface system

ABSTRACT: BACKGROUND: A novel artefact removal algorithm is proposed for a self-paced hybrid brain-computer interface (BCI) system. This hybrid system combines a self-paced BCI with an eye-tracker to operate a virtual keyboard. To select a letter, the user must gaze at the target for at least a specific period of time (dwell time) and then activate the BCI by performing a mental task. Unfortunately, electroencephalogram (EEG) signals are often contaminated with artefacts. Artefacts change the quality of EEG signals and subsequently degrade the BCI's performance. METHODS: To remove artefacts in EEG signals, the proposed algorithm uses the stationary wavelet transform combined with a new adaptive thresholding mechanism. To evaluate the performance of the proposed algorithm and other artefact handling/removal methods, semi-simulated EEG signals (i.e., real EEG signals mixed with simulated artefacts) and real EEG signals obtained from seven participants are used. For real EEG signals, the hybrid BCI system's performance is evaluated in an online-like manner, i.e., using the continuous data from the last session as in a real-time environment. RESULTS: With semi-simulated EEG signals, we show that the proposed algorithm achieves lower signal distortion in both time and frequency domains. With real EEG signals, we demonstrate that for dwell time of 0.0s, the number of false-positives/minute is 2 and the true positive rate (TPR) achieved by the proposed algorithm is 44.7%, which is more than 15.0% higher compared to other state-of-the-art artefact handling methods. As dwell time increases to 1.0s, the TPR increases to 73.1%. CONCLUSIONS: The proposed artefact removal algorithm greatly improves the BCI's performance. It also has the following advantages: a) it does not require additional electrooculogram/electromyogram channels, long data segments or a large number of EEG channels, b) it allows real-time processing, and c) it reduces signal distortion.     

A method to remove CPR artefacts from human ECG using only the recorded ECG

AIM: To show the possibility of using cardiopulmonary resuscitation (CPR) artefact suppression methods that do not need additional reference signals to model CPR artefacts. MATERIALS AND METHODS: A CPR suppression method based on a Kalman filter was designed. The artefact was modelled using the fundamental frequency of the compressions, estimated from the spectral analysis of the ECG. Artificial mixtures of human shockable rhythms and CPR artefacts were used to design the algorithm that was then tested on samples obtained from real out-of-hospital cardiac arrest episodes. RESULTS: The shock/no-shock decision of an automated external defibrillator (AED) was evaluated before and after CPR suppression for 131 shockable and 347 non-shockable samples. The sensitivity improved from 56% (95% CI, 47-64%) to 90% (95% CI, 84-94%). However, the specificity decreased from 91% (95% CI, 87-93%) to 80% (95% CI, 76-84%). CONCLUSIONS: CPR artefacts can be suppressed using methods based on the analysis of the ECG alone. The hardware of current AEDs does not need to be replaced, although better artefact suppression methods exist for modified AEDs with additional reference channels.     

Strong corruption of electrocardiograms caused by cardiopulmonary resuscitation reduces efficiency of two-channel methods for removing motion artefacts in non-shockable rhythms

AimCardiopulmonary resuscitation (CPR) artefact removal methods provide satisfactory results when the rhythm is shockable but fail on non-shockable rhythms. We investigated the influence of the corruption level on the performance of four different two-channel methods for CPR artefact removal.Materials and methods395 artefact-free ECGs and 13 pure CPR artefacts with corresponding blood pressure readings as a reference channel were selected. Using a simplified additive data model we generated CPR-corrupted signals at different signal-to-noise ratio (SNR) levels from ?10 to +10 dB. The algorithms were optimized on learning data with respect to SNR improvement and then applied to testing data. Sensitivity and specificity were derived from the shock/no-shock advice of an automated external defibrillator before CPR corruption and after artefact removal.ResultsSensitivity for the filtered data (>95%) was significantly superior to that for the unfiltered data (76%), p < 0.001. However, specificity was similar for the filtered and unfiltered data (<90% vs 89.3%). For large artefacts (?10 dB) specificity decreased below 70%. No important difference in the performance of the four algorithms was found.ConclusionUsing a simplified data model we showed that, when the ECG rhythm is non-shockable, two-channel methods could not reduce CPR artefacts without affecting the rhythm analysis for shock recommendation. The reason could be poor reconstruction when the artefacts are large. However, poor reconstruction was not a hindrance to re-identifying shockable rhythms. Future investigations should both include the refinement of filter methods and also focus on reducing motion artefacts already at the recording stage.     

颈动脉超声、动态血压及微栓子监测对急性脑梗死患者血管评估的价值

目的探讨颈动脉超声、动态血压及微栓子信号（microemboli signals,MES）监测在急性脑梗死患者血管评估中的价值。方法收集2010年5月至2013年12月经CT或MRI证实的急性脑梗死住院患者157例,均在发病6~48 h内行24 h动态血压监测,并获得动态动脉硬化指数（AASI）;行颈动脉血管超声检查,并获得有颈动脉斑块的患者例数;应用经颅多普勒超声监测仪进行脑动脉MES监测,并观察脑动脉系统存在MES的患者例数。分析MES与AASI、颈动脉斑块的关系。结果 157例急性脑梗死患者中,MES阳性77例,MES阴性80例;颈动脉有斑块者91例,颈动脉无斑块者66例;AASI〉0.51者90例,AASI≤0.51者67例。有颈动脉斑块和AASI〉0.51者的MES阳性构成比分别高于无斑块、AASI≤0.51者[70.1%vs 29.9%,χ2=9.18,P〈0.01;68.8%vs 31.2%,χ2=8.18,P〈0.01]。结论颈动脉超声、动态血压及MES监测对急性脑梗死患者血管评估及预测其风险有一定临床意义。     

Distribution of artificially-produced microembolic signals into the cerebral circulation

According to clinical observations, cardiogenic embolism occurs more often in the anterior than in the posterior cerebral circulation. An ultrasound (US) contrast agent was used to artificially produce microembolic signals (MES) to imitate the intracranial distribution of systemic emboli. Systemic microemboli were simulated by IV administered US agent (Levovist(R) 300 mg/mL as bolus). A total of 20 patients were monitored by means of transcranial Doppler sonography (TCD), 3 min after the injection, with a 2-MHz transducer simultaneously at 50 mm (middle cerebral artery, MCA, on one side) and 90 mm (basilar artery, BA). Four 3-min recordings were done (two of the right MCA, two of the left MCA, with the BA, respectively). Three observers and an automatic detection system independently performed an off-line analysis. A total of 160 recordings were analyzed. The mean numbers of detected high-intensity transient signals (HITS) were 34.5 +/- 28.2 in the right MCA (simultaneously registered HITS in the BA: 9.4 +/- 16.8) and 39.1 +/- 34.2 in the left MCA (simultaneously registered HITS in the BA: 12.2 +/- 14.5). Only 21.4 to 23.7% of all HITS were recorded in the BA. Microembolic signals artificially produced by means of US contrast agent made it possible to mimic the physiologic distribution of small embolic particles. In future, these might help to investigate the distribution of systemic emboli in different vascular territories in various pathologic conditions of the cerebral blood flow.     

Feasibility of shock advice analysis during CPR through removal of CPR artefacts from the human ECG

Mechanical activity from chest compressions and ventilations during cardiopulmonary resuscitation (CPR) introduces artefact components into the electrocardiogram (ECG). CPR must therefore be discontinued for reliable shock advice analysis in automated external defibrillators. Reducing or eliminating this detrimental "hands-off" time by removing the CPR artefacts, should significantly improve the defibrillation success rate. The feasibility of this was tested by removing the CPR artefacts using a multichannel adaptive filter, the multichannel recursive adaptive matching pursuit (MC-RAMP) algorithm. Human ECG and reference channel data from episodes with both shockable and non-shockable underlying heart rhythms were recorded from 105 patients with out-of-hospital cardiac arrest. The performance of a shock advice algorithm was evaluated before and after artefact removal using the MC-RAMP algorithm. From a test set consisting of 92 shockable and 174 non-shockable episodes a sensitivity of 96.7% and specificity of 79.9% was achieved, an increase of approximately 15 and 13%, respectively, compared to no filtering. Good sensitivity was achieved, enabling ECG analysis during CPR that would reduce the hands-off time on patients with shockable rhythms. However, CPR artefact removal on non-shockable rhythms proved a more difficult problem. We need a better understanding of the physiological mixing of artefacts and the underlying heart rhythm and suggest clinical trials to investigate the nature of CPR artefacts further.     

雷公藤内酯醇抑制小鼠肾小球系膜细胞表达CXCL10的实验研究

目的探讨雷公藤内酯醇(triptolide,TPL)对γ干扰素(interferon-γ,IFN-γ)诱导的小鼠肾小球系膜细胞(SV40MES13)表达趋化因子CXCL10 m RNA的影响及其可能机制。方法将对数生长期SV40MES13随机分为空白组、刺激组、干预组,用不同浓度的IFN-γ(0U/ml~2000U/ml)刺激细胞不同时间(0h~48h)后,观察细胞表达CXCL10 m RNA的变化;用CCK-8法检测不同浓度(2ng/ml~20ng/ml)TPL对SV40MES13生存率的影响,选用细胞生存率大于90%的TPL用于后续实验,观察TPL对SV40MES13表达CXCL10 m RNA的影响;选用JAK/STAT信号通路特异性抑制剂AG490干预细胞,探讨IFN-γ是否通过JAK/STAT信号通路诱导CXCL10表达;收集以上细胞,用Real-Time PCR技术检测各组CXCL10 m RNA表达水平。结果 IFN-γ能诱导SV40MES13表达CXCL10 m RNA,并呈时间、剂量依赖性;AG490具有抑制IFN-γ诱导的SV40MES13表达CXCL10 m RNA;TPL具有抑制IFN-γ诱导的SV40MES13表达CXCL10 m RNA的作用。结论 IFN-γ可能通过激活JAK/STAT信号通路,诱导SV40MES13表达CXCL10 m RNA;TPL具有抑制IFN-γ诱导的SV40MES13表达CXCL10的作用。     

Increased cerebral blood flow velocities assessed by transcranial Doppler examination is associated with complement activation after cardiopulmonary bypass

The role of complement activation on the cerebral vasculature after cardiopulmonary bypass (CPB) is unclear. The goal of the study was to assess whether heparin-coated CPB reduces complement activation, and influences cerebral blood flow velocities (CBFV). Twenty-four patients undergoing coronary surgery were randomly allocated to non-coated (NC-group) or heparin-coated (HC-group) CPB. Complement activation was assessed by measuring sC5b-9. Transcranial Doppler (TCD) was performed on middle cerebral arteries before and after CPB. Systolic (SV), diastolic (DV) and mean (MV) CBFV were measured. Significant increase of sC5b-9 (p=0.003) was observed in the NC-group and CBFV increased after CPB (SV by 27%, p=0.05; DV by 40%, p=0.06; MV by 33%, p=0.04) whereas no changes were detected in the HC-group. TCD values were higher in the NC-group than in the HC-group (SV, p=0.04; DV, p=0.03; MV, p=0.03) although cardiac index, systemic vascular resistance, haematocrit and pCO(2) were similar. Postoperative SV, DV and MV were significantly correlated with sC5b-9 (r=0.583, p=0.009; r=0.581, p=0.009; r=0.598, p=0.007, respectively). Increased CBFV after CPB are correlated to the level of complement activation and may be controlled by heparin-coated circuits.