The dynamic distribution of nitric oxide synthase in the small intestine of mice with intestinal radiation sickness

ＴｈｅｄｙｎａｍｉｃｄｉｓｔｒｉｂｕｔｉｏｎｏｆｎｉｔｒｉｃｏｘｉｄｅｓｙｎｔｈａｓｅｉｎｔｈｅｓｍａｌｌｉｎｔｅｓｔｉｎｅｏｆｍｉｃｅｗｉｔｈｉｎｔｅｓｔｉｎａｌｒａｄｉａｔｉｏｎｓｉｃｋｎｅｓｓＷｅｉＬｉｃｈｕｎ（魏丽春）；ＧｕｏＹａｏ（郭鹞）（...     

An Evolutionarily Conserved Region in the Second lntron of the Human Nestin Gene Directs Gene Exmession to CNS Progenitor Cells and to Early Neural Ciest Cells

Central nervous system (CNS) progenitor cells transiently proliferate in the embryonic neural tube and give rise to neurons and glial cells. A characteristic feature of the CNS progenitor cells is expression of the intermediate filament nestin and it was previously shown that the rat nestin second intron functions as an enhancer, directing gene expression to CNS progenitor cells. In this report we characterize the nestin enhancer in further detail. Cloning and sequence analysis of the rat and human nestin second introns revealed local domains of high sequence similarity in the 3' portion of the introns. Transgenic mice were generated with the most conserved 714 bp in the 3' portion of the intron, or with the complete, 1852 bp, human second intron, coupled to the reporter gene lacZ. The two constructs gave a very similar nestin-like expression pattern, indicating that the important control elements reside in the 714 bp element. Expression was observed starting in embryonic day (E)7.5 neural plate, and at E10.5 CNS progenitor cells throughout the neural tube expressed lacZ. At E12.5, lacZ expression was more restricted and confined to proliferating regions in the neural tube. An interesting difference, compared to the rat nestin second intron, was that the human intron at E10.5 mediated lacZ expression also in early migrating neural crest cells, which is a site of endogenous nestin expression. In conclusion, these data show that a relatively short, evolutionarily conserved region is sufficient to control gene expression in CNS progenitor cells, but that the same region differs between rodents and primates in its capacity to control expression in neural crest cells.     

Frequency of T-Cell Progenitors in Nude Mice

The hypothesis that prothymocytes are distinct from and regulated independently of multilineage hemopoietic progenitors was tested by enumeration of these two cell populations in normal versus congenitally athymic (nude) mice. The absence of a thymus and of peripheral T cells in nude mice had no effect on the frequency of either multilineage progenitors (day 12 CFU-S) or prothymocytes (CFU-T), suggesting that there is no feedback regulation of CFU-T frequency. Thymus seeding from the bone marrow is therefore likely to be regulated by the availability of niches for prothymocyte maturation, rather than by feedback control of prothymocyte production.     

A Novel Extravascular Input Function for the Assessment of Drug Absorption in Bioavailability Studies

Purpose. Flexible parametric models describing the input process after extravascular drug administration are needed for the assessment of absorption rate and the use of population methods in bioavailability and bioequivalence studies. Methods. The oral concentration-time curve modeled as the product of the input and disposition function in the Laplace domain was obtained by numerical inversion methods for parameter estimation. The utility of the inverse Gaussian input density was examined using bioavailability data of an extended-release dosage form. Measures of rate of absorption and the cumulative absorbed amount profile were defined in terms of the estimated model parameters. Results. Accurate estimation of absorption parameters was achieved by simultaneous fitting of the extravascular and intravascular data (describing the latter by a triexponential function). The new input function allowed a direct estimation of both extent of absorption and mean absorption time. Conclusions. The findings suggest that the inverse Gaussian density is a useful input function. Its flexibility may reduce the effect of model misspecification in parameter estimation. All parameters can be readily interpreted in terms of the absorption process.     

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。     

Experimental study of the role of the local infectious focus in development ofPseudomonas aeruginosa septicemia

Department of Pathological Anatomy, Clinical-Biological Laboratory, and Laboratory of Immunology, Bacteriology, and Clinical Pharmacology, A. V. Vishnevskii Institute of Surgery, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR D. S. Sarkisov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 111, No. 3, pp. 285–287, March, 1991.     

Precision of three-dimensional CT-assisted model production in the maxillofacial area

Individual skull model fabrication was introduced into preoperative diagnostics in maxillofacial surgery in the mid-1980s. The aim of the present study was to collect information on the reproducibility of a skull model milled from hardened polyurethane foam. This model was based on the CT data of a real skull. Twenty comparative studies were carried out on both the model and the original skull, the model showing an average inaccuracy of 1.6 mm. The deviations ranged between 0.0 and 3.6 mm; the general trend favouring enlargements. The total deviation of the model as compared to the original skull was 1.8%. A convincing aspect of the model, which cannot be obtained by any other method, is its plasticity and the possibility of 3 D orientation on a lifesize model. This new method is already used in preoperative planning of corrections of post-traumatic defects and craniofacial deformities as well as in tumour surgery. Correspondence to: P. Solar     

Effect of temperature in focal ischemia of rat brain studied by 31P and 1H spectroscopic imaging

³¹P, ¹H and lactate spectroscopic imaging was used to evaluate the effects of hypothermia on focal cerebral ischemia produced by middle cerebral artery occlusion. The effects on high energy phosphate metabolism, pH, lactate and NAA were investigated in 24 spontaneously hypertensive rats subjected to either permanent or transient ischemia. Under either normothermic (37.5°C) or hypothermic (32°C) conditions, with permanent 6-h occlusion, there was little difference between groups in either the NMR measurements or the volume of infarction. In animals that underwent 3 h of ischemia followed by 12 h of reperfusion, the ischemic changes in lactate, pH, NAA, and high-energy phosphate returned toward control values, and there was a protective effect of hypothermia (infarct volume of 211 ± 26 and 40 ± 14 mm³ in normothermic and hypothermic groups, respectively). Thus, hypothermia did not ameliorate the changes in lactate, pH, NAA, or high energy phosphate levels occurring during ischemia, however, during reperfusion there was an improvement in both the recovery of these metabolites and pathological outcome in hypothermic compared with normothermic animals.     

矽肺动物模型全肺灌洗治疗的病理观察

通过对动物模型实验治疗的病理观察，评价全肺大容量灌洗治疗矽肺的效果，并优选灌洗液。对４０只家兔和１０只幼猪经ＳｉＯ２染尘处理后，各随机分为药物组、盐水组和对照组。４～５周后施行全肺大容量灌洗。治疗后３～５个月处死各组动物，进行病理双盲检查。经统计学秩和检验，兔与猪各组肺矽结节纤维化级别分布的差异有非常显著意义（Ｐ＜０．００５）。经卡方检验，各灌洗组的纤维化程度与对照组相比，差异亦有非常显著意义（Ｐ＜０．０１）。灌洗液中药与盐水比，Ｐ＜０．０５；盐水与西药比，Ｐ＜０．０５。兔和猪矽肺各灌洗组的效果明显优于对照组。灌洗液中药优于盐水，盐水又优于西药     

三种方案治疗小儿肺炎的药物经济学研究

目的：比较三种方案治疗小儿细菌性肺炎的效率（即费用－效果）。方法：2001年－2002年采用前瞻性随性临床试验A组50例，B组50例，C组50例作为分析模型，以深圳市二级甲等医院收费为标准，采用决策树的分析方法，进行费用一效果分析。结果：每治疗1例有效病人，A、B、C三组方案的期望成本分别为4707．45元，3052．51元，结论：同时考虑临床疗效及医疗费用，C组有最好的费用－效果，值得临床推广应用。