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.     

核黄素缺乏大鼠红细胞维生素E水平的变化及脂质过氧化关系的研究

对两组大鼠分别喂饲核黄素缺乏（ＲＤ）膳和核黄素添加（Ｒ８，２２ｍｇ／ｋｇ饲料）膳８周后，测定了两组大鼠的红细胞维生素Ｅ（ＲＢＬＶｅ）、红细胞超氧化物歧化酶（ＳＯＤ）和红细胞丙二醛（ＭＤＡ）的水平。结果发现：ＲＤ组ＲＢＣＶｅ水平（４．７１７３±０．７７１０ｍｇ／ｇ蛋白质）显著低于ＲＳ组（５。３８６８±１．１５３７ｍｇ／ｇ蛋白质，Ｐ＜０．０５）。而ＲＤ组的ＲＢＣＳＯＤ（７７４５．２±６１０．１ｕ／ｇ蛋白质）和ＭＤＡ（０．６８６８±０．１３７２μｇ／ｇ蛋白质）则分别显著低于和高于ＲＳ组（８２６８．５±３０１．０ｎｕ／ｇ蛋白质，０．５５４８±０．０９８０，Ｐ＜０．０５）。研究提示，核黄素缺乏引起细胞膜脂质过氧化加重可能ＲＢＣＶｅ消耗增加。     

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     

模拟高原和返回平原后大鼠心肌血流量的变化

目的：观察缺氧及停止缺氧后对大鼠心肌血流量的影响。方法：３４只Ｗｉｓｔａｒ大鼠，随机分为４组：①平原对照组；②急性缺氧组；③慢性缺氧组；④返回平原组。以放射性生物微球法测定心肌血流量。结果：急性缺氧引起ＰａＯ２、心输出量及氧运送量降低，但左、右心室心肌血流量明显增加；慢性缺氧时右心室收缩压、血球压积、血液粘滞性及右心室生理指数明显增加，而心肌血流量接近正常。停止缺氧３０ｄ后，上述所有指标均与平原以     

精氨酸加压素（AVP）的衍生物AVP4—8不能作用于AVPV1a受体而诱发电流反应

在微量注射大量肝脏ｍＲＮＡ之后，通过电压箝方法进行功能鉴定，两栖类卵母细胞成功地表达了ＡＶＰＶ１ａ受体。但在灌流ＡＶ４－８溶液时，却不能诱导卵母细胞产生内向振荡电流反应。提示ＡＶＰ４－８不能通过ＡＶＰＶ１ａ受体而介导生理学效应。     

Nutritional Anemias

Prevention of nutritional deficiencies should be attained by the consumption of a good diet. Unfortunately, in the case of iron, this is not always possible, and it is advantageous to fortify food with iron. Milk-based formulas and cereals are the most commonly used iron-fortified products in infancy and early childhood. Bioavailability of iron from cereals is low and more clinical studies on the field are necessary to demonstrate the effectiveness of iron-fortified cereals in infants and children of developing countries. Infections and excessive blood loss in infancy related to the use of fresh, pasteurized or powdered cow milk result in much of the anemia we currently see in industrialized countries. Vitamin A deficiency interacts with iron metabolism and recent intervention studies have shown that anemia in Vitamin A deficient children can be successfully treated with oral supplements.     

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.