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991.
Guo XT  Shi M  Shu MG  Xue Y  Li LW  Liu WC 《Medical hypotheses》2007,68(6):1389-1391
Hematopoietic stem cells transplantation has been wildly used in clinical settings and has shown exciting results in treating a wide variety of diseases. However, the relative small number of hematopoietic stem cells in bone marrow, even lower in peripheral or umbilical cord blood limits its clinical utility. There are several protocols, which have been developed to expand hematopoietic stem cells to reach clinical goal. With the recent insights into the mechanisms of hematopoietic stem cells self-renewal, we postulate that Cdx4, which is coded by one of the caudal related homeobox genes and regulates the expression of hox genes, could fuse with protein transduction domains, thereby get the ability to cross cellular membrane. And the recombinant fusion proteins could be used in expanding hematopoietic stem cells. Meanwhile, Cdx4 fusion proteins would be more efficient than other methods that had been developed for it can up-regulate a cocktail of hox genes, which has been proved to be capable of amplifying hematopoietic stem cells. It would provide us an alternative protocol to amplify hematopoietic stem cells if the hypothesis proved to be practical.  相似文献   
992.
Traditional diagnostic methods do not work well for gastrointestinal bleeding, and location of the haemorrhagic focus is even more difficult. Here a novel method with a microelectronic system is presented effectively to detect and locate the haemorrhagic focus. The outstanding advantage of this method is that it is non-invasive. The composition and working principles of the system are described in detail. Key to this system is the development of a haemoglobin (Hb) sensor. Through MEMS technology a micro haemoglobin sensor is developed and fabricated. The sensor's response performance, pH dependence and temperature dependence are tested experimentally. Initial tests suggest that the device is sufficiently sensitive to Hb concentration and insensitive to pH and temperature changes in the working range. As a result, the system has potential for development of an advanced instrument for detecting, localizing and treating gastrointestinal bleeding.  相似文献   
993.
Blocking layers are used to reduce leakage current in amorphous selenium detectors. The effect of the thickness of the blocking layer on the presampling modulation transfer function (MTF) and on dark current was experimentally determined in prototype single-line CCD-based amorphous selenium (a-Se) x-ray detectors. The sampling pitch of the detectors evaluated was 25 microm and the blocking layer thicknesses varied from 1 to 51 microm. The blocking layers resided on the signal collection electrodes which, in this configuration, were used to collect electrons. The combined thickness of the blocking layer and a-Se bulk in each detector was approximately 200 microm. As expected, the dark current increased monotonically as the thickness of the blocking layer was decreased. It was found that if the blocking layer thickness was small compared to the sampling pitch, it caused a negligible reduction in MTF. However, the MTF was observed to decrease dramatically at spatial frequencies near the Nyquist frequency as the blocking layer thickness approached or exceeded the electrode sampling pitch. This observed reduction in MTF is shown to be consistent with predictions of an electrostatic model wherein the image charge from the a-Se is trapped at a characteristic depth within the blocking layer, generally near the interface between the blocking layer and the a-Se bulk.  相似文献   
994.
A large number of the strain estimation methods presented in the literature are based on the assumption of tissue continuity that establishes a continuous displacement field. However, in certain locations in the body such as the arteries in vivo scanning may produce displacement fields that are discontinuous between the two walls of the artery. Many of the displacement or strain estimators fail when the displacement fields are discontinuous. In this paper, we present a new 2D multi-level motion or displacement tracking method for accurate estimation of the strain in these situations. The final high-resolution displacement estimate is obtained using two processing steps. The first step involves an estimation of a coarse displacement estimate utilizing B-mode or envelope signals. To reduce computational time, the coarse displacement estimates are obtained starting from down-sampled B-mode pre- and post-compression image pairs using a pyramidal processing approach. The coarse displacement estimate obtained from the B-mode data is used to guide the final 2D cross-correlation computations on radio-frequency (RF) data. Results from finite element simulations and in vivo experimental data demonstrate the feasibility of this approach for imaging tissue with discontinuous displacement fields.  相似文献   
995.
抗原修复技术研究进展   总被引:4,自引:0,他引:4  
自从应用抗原修复技术的文章于1991年发表后,抗原修复技术(煮沸石蜡切片于水溶液中)迅速、广泛应用于常规甲醛固定、石蜡包埋组织切片的免疫组织化学染色,从而打开了从传统形态学迈向分子形态学的大门。抗原修复技术被誉为免疫组织化学技术的革命性突破旧。Gown在评价抗原修复技术所取得的成就时,指出“在过去十多年里,抗原修复技术在诊断性免疫组织化学分析方面造成了如此深远的影响,使得这方面的文献分为2个时代:抗原修复技术前与抗原修复技术后时代。20世纪90年代初抗原修复技术的问世就是这两个阶段的分水岭”。  相似文献   
996.

Purpose

We aimed to demonstrate the use of jackknife residuals to take advantage of the longitudinal nature of available growth data in assessing potential biologically implausible values and outliers.

Methods

Artificial errors were induced in 5% of length, weight, and head circumference measurements, measured on 1211 participants from the Maternal Vitamin D for Infant Growth (MDIG) trial from birth to 24 months of age. Each child's sex- and age-standardized z-score or raw measurements were regressed as a function of age in child-specific models. Each error responsible for a biologically implausible decrease between a consecutive pair of measurements was identified based on the higher of the two absolute values of jackknife residuals in each pair. In further analyses, outliers were identified as those values beyond fixed cutoffs of the jackknife residuals (e.g., greater than +5 or less than ?5 in primary analyses). Kappa, sensitivity, and specificity were calculated over 1000 simulations to assess the ability of the jackknife residual method to detect induced errors and to compare these methods with the use of conditional growth percentiles and conventional cross-sectional methods.

Results

Among the induced errors that resulted in a biologically implausible decrease in measurement between two consecutive values, the jackknife residual method identified the correct value in 84.3%–91.5% of these instances when applied to the sex- and age-standardized z-scores, with kappa values ranging from 0.685 to 0.795. Sensitivity and specificity of the jackknife method were higher than those of the conditional growth percentile method, but specificity was lower than for conventional cross-sectional methods.

Conclusions

Using jackknife residuals provides a simple method to identify biologically implausible values and outliers in longitudinal child growth data sets in which each child contributes at least 4 serial measurements.  相似文献   
997.
OBJECTIVE: The purpose of these laboratory studies was to evaluate three toothbrushes for their ability to remove artificial plaque deposits at interproximal sites and along the gingival margin of simulated anterior and posterior teeth, using horizontal and vertical brushing motions. METHODOLOGY: Three toothbrushes were evaluated: elmex SENSITIVE SOFT; elmex SENSITIVE EXTRA SOFT; and the ADA reference. Twenty-four tests on each toothbrush group were conducted, and results were statistically analyzed using ANOVA and the post hoc Tukey test. RESULTS: In both the interproximal access efficacy and gingival margin cleaning assays, the elmex SENSITIVE EXTRA SOFT and SENSITIVE SOFT toothbrushes were statistically superior (p < 0.001) to the ADA reference toothbrush. CONCLUSION: The elmex SENSITIVE SOFT and EXTRA SOFT toothbrushes are predicted to offer excellent plaque removal efficacy interproximal areas and along the gingival margin of both anterior and posterior teeth.  相似文献   
998.
999.
International Urology and Nephrology - The efficacy of the antioxidants vitamin E (VitE) and vitamin C (VitC) on male infertility is uncertain. Therefore, this research systematically assessed the...  相似文献   
1000.
Neurological Sciences - The growth and development of tumors are closely related to the initiation and amplification of the inflammatory response. Various inflammatory biomarkers had attained...  相似文献   
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