周期性压力下椎间盘细胞中肌动蛋白的变化及其意义

目的探讨在周期性压力下,体外培养的椎间盘细胞中的肌动蛋白的变化及其意义。方法采用10只5～6周龄、体重为25～30kg的猪的椎间盘进行体外细胞的分离和培养,对细胞施加周期性液压,通过对细胞的形态学观察及Western免疫印迹和免疫荧光实验,检测在周期性压力下椎间盘细胞中的肌动蛋白的变化。结果纤维环细胞和髓核细胞经1MPa、1Hz,持续每天3h加压,3d后髓核细胞的存活率大于90%,纤维环细胞的存活率大于85%,加压后的纤维环细胞和髓核细胞体积均缩小,由多角形转变为细长形。Western免疫印迹结果显示,肌动蛋白在纤维环细胞和髓核细胞中的表达均明显减少,以髓核细胞为著。免疫荧光结果显示,肌动蛋白由正常纤维环细胞和髓核细胞内的疏松排列转变为受压细胞内的紧密排列,髓核细胞的体积明显缩小,其中的肌动蛋白在细胞膜周围紧密排列。结论体外培养的单层椎间盘细胞在受力状态下,肌动蛋白的表达减少,细胞的体积缩小,并且肌动蛋白在细胞内重排列。这可能是激发细胞内或细胞表面信号传导的重要机制。     

Dynamic changes in sensitization to specific aeroallergens in children raised in a desert environment

BACKGROUND: Allergen skin test reactivity and total serum IgE are objective measures used to characterize and help diagnose allergic diseases. Cross-sectional studies have shown that overall aeroallergen skin test reactivity increases throughout childhood. However, little attention has been paid to whether individual aeroallergen remittance occurs, which could distort or mask relationships to disease. OBJECTIVE: To access the incidence and remittance of skin test reactions to individual allergens in children aged 6-11 years. METHODS: Longitudinal sensitization to six aeroallergens and total IgE were assessed in 828 children raised in the semi-arid US southwest at ages 6 and 11 years. RESULTS: New sensitization (to any allergen) between 6 and 11 years occurred in 30.2% of children compared with 39.7% before age 6 years. The rate of complete remittance from positive to negative between ages 6 and 11 years was 8.2%, and total IgE at age 6 years was not predictive. Remittance rates for individual allergens were high and variable (19-49%). The perennial allergens Bermuda and Alternaria were early sensitizers and had low remittance rates. Early sensitization to the four seasonal allergens was less common and more subject to remittance with the bulk of sensitization occurring between 6 and 11 years. CONCLUSION: This study shows that sensitization to individual aeroallergens in childhood is dynamic and indicates the limitation of single point assessment of skin test reactivity.     

Comparison between broad-band ultrasound attenuation of the calcaneum and total body bone mineral density in children

We measured broad-band ultrasound attenuation (BUA) in the calcaneum using the prototype Paediatric Contact Ultrasound Bone Analyser (CUBA) and total body bone mineral density (TBBMD) using dual-energy X-ray absorptiometry (DXA) (Hologic QDR-1000W) in 58, 7 17-year-old healthy children and adolescents. Calcaneal BUA was significantly related to TBBMD ( r = 0.74, p < 0.001), and both the calcaneal BUA and TBBMD were significantly correlated with age and body weight. We conclude that calcaneal BUA reflects bone mineral density (BMD) in healthy children and adolescents; however, BMD measured by CUBA appears to be less sensitive than that measured by DXA. Since BUA reflects structural properties of bone, as well as density, it may complement radiological techniques of bone density measurement in the assessment of paediatric conditions associated with fracture risk.     

Cavernous hemangioma of the liver: detection with single-photon emission computed tomography

The roles of single-photon emission computed tomography (SPECT) and planar imaging with technetium-99m-labeled red blood cells in the diagnosis of cavernous hemangioma of the liver were evaluated. The study group consisted of 26 consecutive patients referred for evaluation of liver lesions. A total of 23 cavernous hemangiomas were found, all of which showed decreased or normal flow and delayed uptake of the radiotracer. SPECT demonstrated 13 hemangiomas that were not detected with planar imaging; both modalities demonstrated the other ten lesions. Lesions that were not cavernous hemangiomas showed either normal (n = 6) or increased (n = 4) flow; none had delayed increased uptake on either planar or SPECT images. SPECT with labeled red blood cells is an accurate method for the detection of cavernous hemangiomas of the liver and is more sensitive than planar imaging in depicting small lesions.     

Single-point (constant-time) imaging in radiofrequency Fourier transform electron paramagnetic resonance.

This study describes the use of the single-point imaging (SPI) modality, also known as constant-time imaging (CTI), in radiofrequency (RF) Fourier transform (FT) electron paramagnetic resonance (EPR). The SPI technique, commonly used for high-resolution solid-state nuclear magnetic resonance (NMR) imaging, has been successfully applied to 2D and 3D RF-FT-EPR imaging of phantoms containing narrow-line EPR spin probes. The SPI scheme is essentially a phase-encoding technique that operates by acquiring a single data point in the free induction decay (FID) after a fixed delay (phase-encoding time), following the pulsed RF excitation, in the presence of static magnetic field gradients. Since the phase-encoding time remains constant for a given image data set, the spectral information is automatically deconvolved, providing well-resolved pure spatial images. Therefore, images obtained using SPI are artifact-free and the resolution is not significantly limited by the line width, compared to the images obtained using the conventional filtered back-projection (FBP) scheme, suggesting that the SPI modality may have advantages for EPR imaging of large objects. In this work the advantages and limitations of SPI as compared to FBP are investigated by imaging suitable phantom objects. Although SPI takes longer to perform than the FBP method, optimization of the data collection scheme may increase the temporal resolution, rendering this technique suitable for in vivo studies. Spectral information can also be extracted from a series of SPI images that are generated as a function of the delay from the excitation pulse.