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.     

循证医学决策模式的建立与应用

循证医学决策模式是建立在对客观的医学研究证据，长期的临床工作经验，及不同患的医疗需求进行综合分析基础上的最佳医疗方案。其建立和应用对提高医疗质量，改善医疗服务质量具有重要意义。树立循证医学决策意识，建立循证医学决策系统，实施循证医学决策管理将为军队医疗系统实现全面品质管理提供可靠依据。     

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     

Improved intracranial lesion characterization by tissue segmentation based on a 3D feature map

Our aim was to develop an accurate multispectral tissue segmentation method based on 3D feature maps. We utilized proton density (PD), T₂-weighted fast spin-echo (FSE), and T₁-weighted spin-echo images as inputs for segmentation. Phantom constructs, cadaver brains, an animal brain tumor model and both normal human brains and those from patients with either multiple sclerosis (MS) or primary brain tumors were analyzed with this technique. Initially, misregistration, RF inhomogeneity and image noise problems were addressed. Next, a qualified observer identified samples representing the tissues of interest. Finally, k-nearest neighbor algorithm (k-NN) was utilized to create a stack of color-coded segmented images. The inclusion of T₁ based images, as a third input, produced significant improvement in the delineation of tissues. In MS, our 3D technique was found to be far superior to that based on any combination of 2D feature maps (P < 0.001). We identified at least two distinctly different classes of lesions within the same MS plaque, representing different stages of the disease process. Further, we obtained the regional distribution of MS lesion burden and followed its changes over time. Neuropsychological aberrations were the clinical counterpart of the structural changes detected in segmentation. We could also delineate the margins of benign brain tumors. In malignant tumors, up to four abnormal tissues were identified: 1) a solid tumor core, 2) a cystic component, 3) edema in the white matter, and 4) areas of necrosis and hemorrhage. Subsequent neurosurgical exploration confirmed the distribution of tissues as predicted by this analysis.     

关于Reed－Frost模型的研究和改进

笔者提出了对Ｒｅｅｄ－Ｆｒｏｓｔ模型的学术评论，并新建了一种Ｒｅｅｄ－Ｆｒｏｓｔ模型的改进模型。该改进模型全面考虑了隐性感染者的产生、传染作用及向免疫者的转化。应用这个模型，模拟了ＮｅｗＥｎｇｌａｎｄ的麻疹流行和中国上海市某保育院的水痘流行，结果颇为理想。该模型包括了基本的流行要因，故能用以解释流行过程，并可帮助流行病学工作者理解隐性感染在传染病流行过程中的作用。     

rhGM-CSF对小鼠口腔粘膜损伤的防治作用

目的：探讨rhGM-CSF促进口腔腔溃愈合的作用机制。方法：取体外培养的胎儿口腔粘膜成纤维细胞，用rhGM-CSF刺激成纤维细胞后第2、4、6天用细胞计数及^3H－胸腺嘧啶掺入法（^3H-TdR）测定其增殖情况，结果rhGM-CSF对胎儿口腔粘膜成纤维细胞增殖及DNA合成有刺激作用，在80－100ng/ml时，细胞生长达到最佳状态，过高浓度rhGM-CSF的刺激作用反而下降。结论：rhGM-CSF可以通过刺激成纤维细胞增殖及DNA合成促进口腔溃疡愈合。