“Hands‐Free” Continuous Echocardiography during Treadmill Exercise Using a Novel Ultrasound Transducer

Background: Echocardiographic imaging using a handheld transducer in conjunction with treadmill exercise testing is commonly used for the diagnosis of coronary artery disease. Motion of the hand and the transducer during peak exercise preclude optimal imaging. To circumvent the limitations of handheld transducers, we developed a low profile transducer (CONTISON) which can be attached to the chest wall for continuous cardiac imaging. Methods and Results: This feasibility study was performed in 10 normal male subjects (28 to 36 years). The ultrasound transducer was placed in the third or fourth intercostal space at the left sternal border to permit imaging of the left ventricle in its short axis. The transducer was interfaced with a commercially available ultrasound machine. The left ventricle was imaged at rest and while subjects exercised according to a standard Bruce protocol. All segments of the left ventricular short axis were seen at rest and peak exercise. Increased left ventricular wall thickening and wall motion were seen at peak exercise. There were no complications from the procedure. Conclusion: We demonstrated the feasibility of hands‐free left ventricular imaging during treadmill exercise using the CONTISON transducer. Further evaluation of the technique to detect stress‐induced wall motion abnormalities, as a means of diagnosing myocardial ischemia, appears warranted. (ECHOCARDIOGRAPHY 2010;27:563‐566)     

锡兰绿茶中黄酮类成分对缺氧人脑上皮细胞的治疗作用

为研究从锡兰绿茶（Dilmah）提取纯化的黄酮类有效成分对缺氧人脑上皮细胞的治疗作用，体外培养人脑上皮细胞（HBEC），给与锡兰绿茶黄酮提取物治疗后造缺氧模型，检测锡兰绿茶中的黄酮类化合物的抗氧化活性及脑细胞的生存情况，探究其对缺氧脑细胞氧化应激的影响。生化检测显示锡兰绿茶提取物的自由基的清除抑制率（ABTS）为68％±2．8％，次氯酸漂白邻苯三酚红抑制率为79％±4．5％。缺氧后，空白对照组细胞生存率为29％±2．3％，而锡兰绿茶黄酮提取物治疗组为41％±4．7％，氯沙坦治疗组为39％±3．1％。同时，黄铜提取物与氯沙坦治疗组LDH释放分别减少75％±3．7％和79％±3．5％。锡兰绿茶的黄酮提取物治疗使细胞抗氧化酶活力显著增强，SOD：（1．5±0．6）μmol／min／mg蛋白，CAT：（0．61±0．06）μmol／min／mg蛋白，GPx：（2．6±0．41）μmol／min／mg蛋白，GST：（6．0±2．4）μmol／min／mg蛋白，显著高于缺氧对照组，其酶活力分别为：（0．5±0．52，51±0．04，1．2±0．35，3．1±1．6）μmol／min／mg蛋白。研究结果表明，锡兰绿茶有很大的临床应用价值。饮用锡兰绿茶可能成为预防中风的有效新方法，并能减少现代疾病对生命的威胁，提高人类生活质量。     

Modeling centrifugal cell washers using computational fluid dynamics

Reinfusion of shed blood during surgery could avoid the need for blood transfusions. Prior to reinfusion of the red blood cells, the shed blood must be washed in order to remove leukocytes, platelets, and other contaminants. Further, the hematocrit of the washed blood must be increased. The feasibility of using computational fluid dynamics (CFD) to guide the design of better centrifuges for processing shed blood is explored here. The velocity field within a centrifuge bowl and the rate of protein removal from the shed blood has been studied. The results obtained indicate that CFD could help screen preliminary centrifuge bowl designs, thus reducing the number of initial experimental tests required when developing new centrifuge bowls. Although the focus of this work is on washing shed blood, the methods developed here are applicable to the design of centrifuge bowls for other blood-processing applications.     

In vivo cardiovascular magnetic resonance diffusion tensor imaging shows evidence of abnormal myocardial laminar orientations and mobility in hypertrophic cardiomyopathy

Background

Cardiac diffusion tensor imaging (cDTI) measures the magnitudes and directions of intramyocardial water diffusion. Assuming the cross-myocyte components to be constrained by the laminar microstructures of myocardium, we hypothesized that cDTI at two cardiac phases might identify any abnormalities of laminar orientation and mobility in hypertrophic cardiomyopathy (HCM).

Methods

We performed cDTI in vivo at 3 Tesla at end-systole and late diastole in 11 healthy controls and 11 patients with HCM, as well as late gadolinium enhancement (LGE) for detection of regional fibrosis.

Results

Voxel-wise analysis of diffusion tensors relative to left ventricular coordinates showed expected transmural changes of myocardial helix-angle, with no significant differences between phases or between HCM and control groups. In controls, the angle of the second eigenvector of diffusion (E2A) relative to the local wall tangent plane was larger in systole than diastole, in accord with previously reported changes of laminar orientation. HCM hearts showed higher than normal global E2A in systole (63.9° vs 56.4° controls, p = 0.026) and markedly raised E2A in diastole (46.8° vs 24.0° controls, p < 0.001). In hypertrophic regions, E2A retained a high, systole-like angulation even in diastole, independent of LGE, while regions of normal wall thickness did not (LGE present 57.8°, p = 0.0028, LGE absent 54.8°, p = 0.0022 vs normal thickness 38.1°).

Conclusions

In healthy controls, the angles of cross-myocyte components of diffusion were consistent with previously reported transmural orientations of laminar microstructures and their changes with contraction. In HCM, especially in hypertrophic regions, they were consistent with hypercontraction in systole and failure of relaxation in diastole. Further investigation of this finding is required as previously postulated effects of strain might be a confounding factor.

Electronic supplementary material

The online version of this article (doi:10.1186/s12968-014-0087-8) contains supplementary material, which is available to authorized users.     

A novel multimodal platform for assessing surgical technical skills

BackgroundEstablished methods for assessing surgical performance face limitations. Global rating scales and procedure-specific checklists are resource intensive and rely on expert opinions. Alternatives that use technology to track hand movements, such as magnetic and optical tracking systems, are generally expensive and ill suited to the surgical environment.MethodsThe authors present a new platform that integrates a novel, low-cost optical tracking system, magnetic tracking technology and a videographic recording system to quantify surgical performance synchronously across all modalities. The validity of this platform was tested by examining its ability to differentiate between the performance of expert and novice participants on a basic surgical task.ResultsEach modality was able to differentiate between expert and novice participants, and metrics were well correlated across modalities.ConclusionsThe authors have developed a platform for assessing surgical performance. It can operate in the absence of expert raters and has the potential to provide immediate feedback to trainees.     

Effects of spatial separation and stimulus probability on the event-related potentials elicited by occasional changes in sound location

The ability to extract information about the spatial location of sounds plays an important role in auditory scene analysis. The present study examined the effects of spatial separation and stimulus probability on auditory event-related potentials (ERPs) to changes in sound location. In Experiment 1, we found that difference waves between ERPs elicited by standard and deviant stimuli showed a biphasic negative-positive response peaking around 126 and 226 ms after deviant onset. The amplitude of both responses increased with decreasing deviant stimulus probability, and increasing stimulus deviance. When the same stimuli were presented with equal probability for all locations (Experiment 2), there were no significant differences in the ERP amplitude and latency. These results suggest that the data reported in Experiment 1 are the result of contextual changes, rather than changes in simple acoustic features. Brain electrical source analyses are consistent with generators located in auditory cortices posterior to Heschel's gyrus. Although occasional changes in sound location elicit earlier peaks than the mismatch negativity (MMN) response reported for other types of deviation, their topographical distribution and behavior are consistent with MMN. The early latency of MMN for changes in sound location is interpreted in the context of an early-warning system to alert the organism to new sound sources in the environment.