Determinants of the exclusion zone in dopaminergic amacrine cell mosaics

A fundamental organizing feature of the retina is the presence of regularly spaced distributions of neurons, yet we have little knowledge of how this patterning emerges during development. Among these retinal mosaics, the spatial organization of the dopaminergic amacrine cells is unique: using nearest-neighbor and Vornoi domain analysis, we found that the dopaminergic amacrine cells were neither randomly distributed, nor did they achieve the regularity documented for other retinal cell types. Autocorrelation analysis revealed the presence of an exclusion zone surrounding individual dopaminergic amacrine cells and modeling studies confirmed this organization, as the mosaic could be simulated by a minimal distance spacing rule defined by a broad set of parameters. Experimental studies determined the relative contributions of tangential dispersion, fate determination, and cell death in the establishment of this exclusion zone. Clonal boundary analysis and simulations of proximity-driven movement discount tangential dispersion, while data from bcl-2 overexpressing mice rule out feedback-inhibitory fate-deterministic accounts. Cell death, by contrast, appears to eliminate dopaminergic amacrine cells that are within close proximity, thereby establishing the exclusion zone surrounding individual cells and in turn creating their mosaic regularity.     

Detecting dose-response using contrasts: asymptotic power and sample size determination for binomial data

Recently, Stewart and Ruberg proposed the use of contrast tests for detecting dose-response relationships. They considered in particular bivariate contrasts for healing rates and gave several possibilities of defining adequate sets of coefficients. This paper extends their work in several directions. First, asymptotic power expressions for both single and multiple contrast tests are derived. Secondly, well known trend tests are rewritten as multiple contrast tests, thus alleviating the inherent problem of choosing adequate contrast coefficients. Thirdly, recent results on the efficient calculation of multivariate normal probabilities overcome the traditional simulation-based methods for the numerical computations. Modifications of the power formulae allow the calculation of sample sizes for given type I and II errors, the spontaneous rate, and the dose-response shape. Some numerical results of a power study for small to moderate sample sizes show that the nominal power is a reasonably good approximation to the actual power. An example from a clinical trial illustrates the practical use of the results.     

Immunohistochemical detection of chemokines in human skin wounds and its application to wound age determination

Immunohistochemical studies on the time-dependent expression of the chemokines such as interleukin (IL)-8, monocyte chemoattractant protein (MCP)-1 and macrophage inflammatory protein (MIP)-1α were performed on 50 human skin wounds with different wound ages (group I 0–12 h, group II 1–4 days, group III 7–14 days and group IV 17–21 days). In the wound specimens with wound ages between 4 and 12 h, neutrophils mainly showed positive reactions for IL-8, MCP-1 and MIP-1α. With increasing wound ages, macrophages and fibroblasts were positively stained with anti-IL-8, MIP-1α and MCP-1 antibodies. Morphometrically, there was a similar distribution in the positive ratios of the inflammatory cells among IL-8, MCP-1 and MIP-1α. The positive ratios of each chemokine were very low in group I and a considerable increase of the positive ratios in each chemokine was observed in group II (mean ± standard error IL-8: 59.8 ± 2.1%, MCP-1: 42.4 ± 3.1% and MIP-1α: 50.4 ± 3.7%). Although the positive ratios for each chemokine gradually decreased according to the wound age, the mean positive ratios in groups III and IV were significantly higher than those in group I. From the forensic aspect, these chemokines are considered useful markers for wound age determination. Thus, ratios of > 50% for IL-8, > 30% for MCP-1 or > 40% for MIP-1α indicate a wound age of at least 1 day. Moreover, the combined investigation of these three chemokines can make wound age determination more objective and accurate. Received: 30 May 2001 / Accepted: 14 August 2001     

高效液相色谱法测定普卢利沙星的含量

目的建立普卢利沙星的含量测定方法。方法采用高效液相色谱法;Alltima C18柱(150mm×4.6mm,5μm);乙腈∶0.005mol/L磷酸二氢钠溶液(取0.005mol/L磷酸二氢钠溶液100ml,加三乙胺0.2ml,用磷酸调节pH值至6.0)(40∶60)为流动相;流速1.0ml/min,检测波长278nm。结果普卢利沙星在12.8~204.1μg/ml浓度范围内呈现良好的线性关系,r=0.9999。结论该方法快速、简捷、准确都高,适用于普卢利沙星的含量测定。     

抱茎苦荬菜药材中木犀草素-7-O-β-D-吡喃葡萄糖苷的分离与含量测定

目的建立分离、测定抱茎苦荬菜药材中木犀草素7OβD葡萄糖苷的方法。方法采用醇提取、氯仿萃取与硅胶柱分离等手段来分离木犀草素7OβD葡萄糖苷;采用RP HPLC法进行含量测定,色谱条件为:Diamonsin C18(250 mm×4.6 mm,5μm)色谱柱,以质量分数为0.2%的磷酸溶液甲醇(体积比为67∶33)为流动相,检测波长为260 nm,流速为0.8 mL.min-1。结果木犀草素7OβD葡萄糖苷质量浓度在4.80~24.0 mg.L-1内线性关系良好(r=0.999 7,n=5),平均回收率为99.4%,相对标准差(RSD)为0.97%。结论本法适合测定抱茎苦荬菜药材中木犀草素7OβD葡萄糖苷的含量。     

反相高效液相色谱法测定高效止痒去痱露中醋酸曲安奈德的含量

目的建立反相高效液相色谱法(RP-HPLC法)测定高效止痒去痱露中醋酸曲安奈德的含量。方法以C18反相键合硅胶为固定相,甲醇-水(75∶25)为流动相,流速1.0mL.m in-1,醋酸地塞米松为内标,检测波长为240nm。结果醋酸曲安奈德在3.0~60.0μg.mL-1浓度范围内呈良好线性关系,r=0.9999,方法平均回收率为99.71%,RSD=0.43%(n=6)。结论该方法测定醋酸曲安奈德的含量简便快捷,适于医院制剂的含量测定。     

HPLC-ELSD法测定复方氨基葡萄糖片中硫酸软骨素的含量

目的建立以蒸发光散射为检测器(ELSD)测定复方氨基葡萄糖片中硫酸软骨素的高效液相色谱分析方法。方法采用高效液相色谱法,以乙腈-水-三乙胺溶液(10∶90∶0.1)为流动相,ODS色谱柱为色谱柱,蒸发光散射检测器检测。结果硫酸软骨素在1.5~21μg范围与峰面积呈良好线性关系;该方法3个不同浓度的平均回收率分别为99.33%,98.29%,98.95%,重复性实验的RSD为0.15%。结论本方法准确、快速、重复性好。     

染料比色法测定硫酸卡那霉素滴眼液中主药的含量

目的:建立以染料比色法测定硫酸卡那霉素滴眼液中主药含量的方法。方法:依据卡那霉素与溴甲酚绿在pH值为6.0时的磷酸盐缓冲液中反应生成离子对化合物的光谱特征,于432nm波长处测定吸收度并计算含量。结果:卡那霉素检测浓度在18.0～72.0μg/ml范围内与吸收度呈良好的线性关系(r=0.9998),平均回收率为99.3%(RSD=1.20%)。结论:本方法快速、简便,可用于该制剂生产过程中的快速检验。     

高效液相色谱法测定雷公藤饮片中雷公藤内酯醇的含量

目的:建立以高效液相色谱(HPLC)法测定雷公藤饮片水提物中雷公藤内酯醇含量的方法。方法:样品分别用氯仿和乙酸乙酯超声萃取,经中性氧化铝柱洗脱分离后,在流动相为乙腈-水(23∶77)、流速为1.0ml/min、检测波长为218nm条件下测定含量并进行比较。结果:雷公藤内酯醇检测浓度线性范围为2.74～96μg/ml(r=0.9999),平均回收率分别为94.78%(RSD=1.57%)、98.2%(RSD=1.7%)。结论:2种含量测定方法均可用于雷公藤内酯醇的质量控制,尤以乙酸乙酯处理样品的方法分离、测定效果较好。     

原子吸收光谱法测定人血中铅含量

目的:研究以石墨炉原子吸收光谱法测定人血中铅含量。方法:取全血100μl,加入400μl0.1%TritonX-100稀释,于283.3nm波长处测定原子吸收。结果:血铅的检测浓度为40～640ng/ml(r=0.9999);石墨管管内变异RSD为2.63%～9.74%,管间变异RSD为14.31%～21.00%;方法回收率为98.4%～119.35%。结论:本方法简便、快速、准确,可用于测定人血中铅含量。