Chemotransport contributes to the effect of oscillatory fluid flow on human bone marrow stromal cell proliferation

Mechanical loads produce a diverse set of biophysical signals that may regulate bone cell activity, but accumulating evidence suggests that interstitial fluid flow is the primary signal that bone cells perceive. Because we previously demonstrated that oscillatory fluid flow increases human bone marrow stromal cell proliferation, we investigated the contribution of fluid shear stress and chemotransport, two stimuli induced by interstitial fluid flow. Alterations in flow rate at a constant peak shear stress were associated with decreases in oscillatory fluid flow‐induced marrow stromal cell proliferation, while variations in peak fluid shear stress had no significant effect. Modulation of marrow stromal cell proliferation by flow rate may be attributed to changes in the release of ATP and intracellular calcium signaling. We found that if the flow rate is decreased while maintaining a constant peak fluid shear stress, marrow stromal cells release less ATP into the extracellular environment. Moreover, as the flow rate decreased fewer cells respond to fluid flow with an increase in intracellular calcium concentration. These data suggest that chemotransport is a prerequisite for marrow stromal cells to respond to interstitial fluid flow. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:918–924, 2008     

Dispersion of Filtered P Wave Duration by P Wave Signal-Averaged ECG Mapping System:

INTRODUCTION: Although it is desirable to know drug efficacy before initiating antiarrhythmic therapy, there have been no methods for this evaluation. P wave signal-averaged ECG (P-SAECG) is useful to detect subtle changes in disturbance of atrial conduction. The purpose of this present study was to test whether P-SAECG mapping system would give any information on the efficacy of disopyramide on the prevention of paroxysmal atrial fibrillation (PAF). METHODS AND RESULTS: P-SAECG was performed before disopyramide treatment, at 3 hours after a single dose of oral disopyramide (200 mg), and after 4 weeks of disopyramide treatment (300 mg/day). After measuring the filtered P wave duration by the vector magnitude and mapping methods, we calculated filtered P wave duration dispersion, difference between the maximal and minimal filtered P wave duration within 16 chest leads at these three time points. Filtered P wave duration and filtered P wave duration dispersion before treatment were longer in 32 patients with symptomatic PAF than in 31 healthy volunteers. Disopyramide was effective for suppression of PAF in 17 patients and ineffective in 15 patients after 4 weeks of treatment. Filtered P wave duration was similarly prolonged at 3 hours in the two groups, whereas filtered P wave duration dispersion at 3 hours after the disopyramide administration behaved differently; it decreased in all of the effective group and increased in all of the ineffective group. The effective patients were prospectively followed with the same treatment for 6 months. In 16 (94%) of these 17 effective patients, no PAF was documented and they remained to be asymptomatic. CONCLUSIONS: Thus, measuring filtered P wave duration dispersion with the P-SAECG mapping method after a single administration may predict the long-term efficacy of disopyramide in patients with PAF.     

Shear Capacity and Behaviour of Bending Reinforced Concrete Beams Made of Steel Fibre-Reinforced Waste Sand Concrete

Inthis paper, we report the results of our research on reinforced concrete beams made of fine aggregate fibre composite, with the addition of steel fibres at 1.2% of the composite volume. The fine aggregate fibre composite is a novel construction material, in which the aggregate used is a post-production waste. Twenty reinforced concrete beams with varying degree of shear reinforcement, in the form of stirrups with and without the addition of steel fibres, tested under loading. The shear capacity results of reinforced concrete beams made of the fine aggregate fibre composite being bent by a transversal force, as well as the cracking forces causing the appearance of the first diagonal crack, are discussed. The stages of functioning of such elements are described. Furthermore, the effect of the steel fibres on the reduction of diagonal cracking is analysed. Computation of the shear capacity of the tested elements is performed, based on the Model Code 2010 and RILEM TC-162 TDF standards, for two variants of the compression strut inclination angle θ that measured during testing, and the minimum(in accordance with the Model Code 2010 standard). We found that the SMCFT method part of Model Code 2010 showed the best compatibility with the experimental results. The tests and analyses performed demonstrate that the developed novel fibrecomposite—the properties of which are close to, or better than, those of the ordinary concrete—can be used successfully for the manufacturing of construction elements in the shear capacity aspect. The developed fine aggregate fibrecomposite could serve, in some applications, as an alternative to ordinary concrete.     

Microfluidic Cell Separation by 2-dimensional Dielectrophoresis

We describe a microfluidic device for separating cells according to their dielectric properties by combining 2-dimensional dielectrophoretic forces with field-flow-fractionation. The device comprises a thin chamber in which a travelling-wave electrical field is generated by a planar, multilayer microelectrode array at the bottom. Under the balance of gravitational and dielectrophoretic levitation forces, cells introduced into the device are positioned at different equilibrium heights in a velocity profile established inside the chamber, and thereby transported at different velocities by the fluid. Simultaneously, cells are subjected to a horizontal travelling-wave dielectrophoretic force that deflects them across the flow stream. The 2-dimensional dielectrophoretic forces acting on cells and the associated velocities in the fluid-flow and travelling-field directions depend sensitively on cell dielectric properties. The responses of cultured MDA-435 human breast cancer, HL-60 human leukemia and DS19 murine erythroleukemia cells, and of peripheral blood mononuclear (PBMN) cells were studied as functions of the frequency and voltage of the applied electric signals, and of the fluid flow rate. Significant differences were observed between the responses of different cell types. Cell separation was demonstrated by the differential redistribution of MDA-435 and PBMN cells as they flowed through the device. The device can be readily integrated with other microfluidic components for microscale sample preparation and analysis.     

超声波治疗脑梗塞偏瘫的疗效观察

目的　观察超声波治疗脑梗塞偏瘫患者的疗效。方法　８９ 例脑梗塞偏瘫患者用超声波治疗，超声频率０ ．８ ＭＨｚ，剂量０ ．７５ ～１ ．２５ Ｗ／ｃｍ ，每日１ 次，每次２０ 分钟，１ 个疗程１０ 天。在超声波治疗前后，患者偏瘫肢体功能评测采用神经功能缺损积分减少的百分比评定。结果　超声波治疗组总有效率９３ ．３ ％ ，对照组７３ ．２ ％ ，差异有显著意义（Ｐ 值＜ ０ ．０１） 。结论　用超声波治疗脑梗塞偏瘫疗效好，无痛苦，患者乐于接受，值得临床推广应用。     

Continuous wave Doppler umbilical artery blood flow velocity wave forms in drug addicted mothers

Summary Continuous wave Doppler umbilical artery blood flow velocity wave form is presented in 14 drug addicted mothers between 22–40 weeks of gestational age from New York City. The mean S/D ratio ranged from 2.36 to 4.30. Doppler study of the fetal umbilical artery could be a valuable addition for assessment of fetal well being in drug addicted mothers.     

Anatomical interconnections of the pedunculopontine tegmental nucleus and the nucleus prepositus hypoglossi in the cat

The Pedunculopontine tegmental nucleus (PPT) is a mesopontine structure containing predominantly cholinergic neurons, and physiological data indicate its neurons transfer eye-movement gated ponto-geniculo-occipital (PGO) waves to thalamus during the rapid eye movement phase of sleep. The present study, using anterograde and retrograde tracing of wheat germ agglutinin-conjugated horseradish peroxidase, found that the medullary nucleus Prepositus hypoglossi (PH), whose neurons are known to have eye-movement-related information, projects densely to PPT, and PPT has reciprocal projections to PH. The PH-PPT projection has some topographic organization, with rostral PH to rostral PPT and caudal PH to caudal PPT projections dominating. The PH-PPT projection may furnish the anatomical substrate for input of eye movement-related information into the rostral PGO wave system.     

The relationship between vascular wall shear stress and flow-mediated dilation: endothelial function assessed by phase-contrast magnetic resonance angiography

OBJECTIVES

We sought: 1) to investigate the relationship between vascular wall shear stress and flow-mediated dilation (FMD) in humans, and 2) to investigate whether this relationship could explain why FMD is greater in small arteries.

BACKGROUND

Arterial wall shear stress (WSS) is considered to be the primary stimulus for the endothelial-dependent FMD response. However, the relationship between WSS and FMD has not been investigated in humans. Furthermore, FMD is greater in small arteries, though the reasons for this phenomenon are unclear.

METHODS

Using phase-contrast magnetic resonance angiography (PMRCA), we measured hyperemic WSS and FMD in 18 healthy volunteers. Peak systolic WSS was calculated assuming a blunted parabolic velocity profile. Diameter by PCMRA and by ultrasound was compared in nine subjects.

RESULTS

Flow-mediated dilation was linearly proportional to hyperemic peak systolic WSS (r = 0.79, P = 0.0001). Flow-mediated dilation was inversely related to baseline diameter (r = 0.62, P = 0.006), but the hyperemic peak WSS stimulus was also inversely related to baseline diameter (r = 0.47, P = 0.049). Phase-contrast magnetic resonance angiography and ultrasound diameters were compared in nine subjects and correlated well (r = 0.84, p < 0.0001), but diameter by PCMRA was greater (4.1 ± 0.7 mm vs. 3.7 ± 0.5 mm, P = 0.009).

CONCLUSIONS

Arterial FMD is linearly proportional to peak hyperemic WSS in normal subjects. Thus, the endothelial response is linearly proportional to the stimulus. Furthermore, the greater FMD response in small arteries is accounted for, at least partially, by a greater hyperemic WSS stimulus in small arteries. By allowing the calculation of vascular WSS, which is the stimulus for FMD, and by imaging a fixed arterial cross-section, thus reducing operator dependence, PCMRA enhances the assessment of vascular endothelial function.     

益肾排石中药保护高能冲击波致肾损伤的实验研究

目的：探讨益肾排石中药对高能冲击波致肾损伤的保护作用。方法：将家兔30只随机分为两组，中药组和生理盐水对照组各15只，于高能冲击波致兔肾损伤模型，测定不同时间血浆，肾组织浆浆内皮素（ET－1），超氧化物歧化酶（SOD）、丙二醛（MDA）变化及肾组织病理改变。结果：冲击波肾损伤后血浆中ET－1、血清中MDA值及组织均浆中ET－1、MDA值显著升高（P＜0．05），血浆及组织匀浆中SOD显著降低（P＜0．05）；而中药治疗组血浆中ET－1、MDA及组织均浆中ET－1、MDA峰值显著低于对照组（P＜0．05），血浆及组织匀浆中SOD值高于对照组（P＜0．05），且病理检查较对照组损伤轻。结论：益肾排石中药对高能冲击波致肾损伤具有保护作用。