UB-I粘结剂粘结面的微形态观察

目的：研究UB-Ⅰ粘结剂的粘结界面和粘结表面的微形态特点。方法：用扫描电子显微镜观察UB-Ⅰ和牙本质的粘结界面和粘结表面。结果：UB-Ⅰ粘结剂在牙本质小管内可聚合形成树脂突，在牙本质小管内的树脂突表面有树脂侧枝呈树枝状横行排列，并且和相邻的树脂突相连接，在牙本质和复合树脂之间有杂合层形成。结论：UB-Ⅰ粘合剂具有良好的渗透性，与牙本质之间可以形成良好的机械嵌合。     

基于LVQ的自发脑电信号的分类研究

为了识别在不同思维状态下的自发脑电(EEG)信号，本文用6阶自回归(AR)模型表示EEG信号，用学习矢量量化(LVQ)神经网络作分类器，分别用LVQl和LVQ2．1算法对网络进行训练，并对分类结果进行测试，比较了网络选择不同参数时对分类正确率的影响。研究表明：竞争层神经元数目直接影响了正确率，当选择最佳参数值时分类正确率为62％-83％，因人而异。     

霉变谷物中霉菌毒素的污染调查

应用酶联免疫吸附测定法和薄层色谱法,对安徽、河南部分地区1991年因特大洪涝灾害造成粮食霉变而引起食物中毒的小麦和大米样品,进行了霉菌毒素[黄曲霉毒素B_1(AFB_1)、脱氧雪腐镰刀菌烯醇(DON)、T-2毒素(T-2)及赭曲霉毒素A(OA)等]的检测。在测定的样品中,检出了高含量的DON和T-2。其中,霉变小麦中,T-2的污染阳性率为96.9%。最高含量为1064.4μg/kg,平均含量为212.1μg/kg;6份霉变大米中,T-2平均含量达532.0μg/kg。     

Determination of residual Kryptofix 2.2.2 levels in [F]-labeled radiopharmaceuticals for human use

4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane (Kryptofix^® 2.2.2) is used in the routine preparation of [¹⁸F]-labeled tracers employed in positron emission tomography (PET) imaging. Confirming the absence of Kryptofix^® in radiopharmaceuticals is a quality control criterion required before they can be released for human use. Analysis of Kryptofix^® levels using the iodoplatinate spot-test can be complicated by false-positive results due to nitrogen containing tracers and/or false-negative results caused by added stabilizers. To overcome this issue, we have developed a universal TLC method for the rapid and reliable determination of Kryptofix^® levels in the wide range of fluorine-18 radiopharmaceuticals we prepare, including complex multi-component formulations.     

Cellular degeneration and synaptogenesis in the developing retina of the rat

We have investigated the time course and magnitude of cellular degeneration in the ganglion cell layer and the presumptive amacrine and bipolar regions of the inner nuclear layer during the development of the retina in the rat. Pyknotic profiles are present in the ganglion cell layer during the first 2 postnatal weeks, reaching peak numbers during the first 4 postnatal days (corresponding to the time of greatest loss of ganglion cells and their axons: Potts et al., '82; Lam et al., '82; Perry et al., '83). Two observations suggest that the majority of pyknotic profiles present in the ganglion cell layer during the second postnatal week are not ganglion cells. First, following injection of kainic acid into one superior colliculus, degenerating ganglion cells in the contralateral retina are cleared within 24-48 hours. Therefore, since most ganglion cell and axon loss occurs within the first postnatal week, few of the pyknotic profiles present in the second week are likely to be ganglion cells. Second, the time course of cellular degeneration in the ganglion cell layer during the second postnatal week follows a very similar pattern to that seen in the presumptive amacrine sublayer of the inner nuclear layer. Such a correspondence suggests that two phases of cell death occur in the ganglion cell layer: during the first postnatal week the majority of dying cells are ganglion cells, and in the second, most cell death is due to a loss of displaced amacrine cells. In the inner nuclear layer pyknotic profiles are most numerous in the presumptive amacrine region on postnatal days 6 and 7, and in the presumptive bipolar region on day 10. Synaptogenesis in the inner plexiform layer occurs later but reflects the order of cell death. Thus, conventional (presumed amacrine) synapses were first observed on day 11 and synaptic ribbons (indicative of bipolar synapses) on day 13. These observations suggest that amacrine and bipolar cells initiate synapses only after their numbers have stabilized.     

胃癌中性糖脂的分离及纯化

作者应用甲醇氯仿抽提胃癌总脂,经sephadex-A25离子交换层析,florisil层析的方法从28g胃癌组织中分离纯化出中性糖脂(?)1.1mg,经高效薄层色谱分析,与标准品对照证实,条带清楚,纯度可靠。为胃癌中性糖脂抗原的研究打下了基础。     

带血管蒂肠浆肌层环贴术防治肠瘘

本文报导用带蒂血管肠浆肌层环贴术防治各种复杂肠瘘,经过十一年的临床观察,疗效满意。本文还着重介绍了手术方法及操作过程中应注意的问题。     

Occupational allergic contact dermatitis and composition of acrylates in dentin bonding systems

Background Dentin-bonding systems contain sensitizing acrylates. They are increasingly used in dentistry, but only few cases of allergy have been encountered. Objective This study reports observations on eleven patients sensitized by acrylates in dentin-bonding compounds. Furthermore, the composition of dentin-bonding products was analysed and compared with the information given in the material safety data sheets. Methods Patch testing was performed to reveal allergic contact dermatitis, and chamber provocation tests to reveal possible respiratory sensitivity. Gas chromatography/mass spectrometry was used to analyse the chemical composition of the bonding products. Results The most common sensitizer in our material of eleven patients was 2-hydroxyethyl methacrylate (2-HEMA). Another putative sensitizer, BIS-GMA, used in dentin adhesives, did not cause sensitization. The typical allergic dermatitis localized to the fingertips (pulpitis). Seven of the eleven patients also developed paresthesia of the fingertips. One patient with positive patch test reactions to (meth)acrylates had pharyngitis hut no skin symptoms. One patient was sensitized because she had been patch tested with too high a concentration (undiluted) of dentin-bonding components. Material safety sheets gave inaccurate or wrong information about the contents. Conclusion Dentin-bonding acrylates are strong sensitizers, and even a single exposure may sensitize.     

Age estimation in biopsy specimens of dentin

Determination of age at death on the basis of aspartic acid racemization in dentin is one of the most reproducible and accurate methods. In Germany, age estimation by this method has so far generally not been applied to living persons, since the extraction of a tooth exclusively for age estimation when it is not medically indicated is regarded as ethically and legally problematic. The development of a biopsy technique applicable to dentin took place against this background. Testing the technique and analysis of dentinal biopsy specimens revealed that the biopsy technique is a low-risk procedure that causes only minor discomfort to the affected person. It is readily practicable and facilitates standardized specimen removal. The relationship between the extent of aspartic acid racemization in dentinal biopsy specimens and age is very close, facilitating age estimation. A prerequisite for accurate results is the performance of biopsies under strictly standardized conditions. If this is guaranteed, age determination on the basis of aspartic acid racemization in dentinal biopsy specimens appears to be superior in precision to most other methods in living persons and can be used for all age groups.     

薄层色谱溶剂系统的最优化方法——Ⅵ.均匀设计法的再探讨

就第Ⅱ报及第Ⅴ报提出的用于选取薄层色谱最佳溶剂系统的均匀设计法进行了进一步的改进及实验验证,使其更趋完善。结果表明,该法不仅适用于已知混合物,而且适用于未知混合物,是一种比较简捷、快速且行之有效的方法。