颈椎前路椎体间微创融合器的生物力学实验研究

目的评价植入镍钛记忆合金微创融合器(NiTi-TFC/C)的颈椎节段的稳定性及压缩力学性能。方法采集24只羊颈椎标本随机分为4组,每组6份,四组处理分别为:单取髓核组、自体髂骨植骨组、微创融合器组和钛制融合器组(InterFix)。所有标本进行前路减压,并对后3组进行椎间融合术。分别对各组标本进行生物力学测试并进行比较。结果微创融合器组与钛制融合器组在强度、刚度及扭转力学等方面无显著性差异(P>0.05)。而微创融合器组与自体髂骨植骨组具有显著性差异(P<0.05)。最大承载力为12050N。结论该微创融合器强度大、刚度高、抗扭转能力强,具有良好的抗压能力,为颈椎融合提供新型的融合装置。     

免疫透射比浊法测定血清免疫球蛋白

本文报道免疫透射比浊法测定血清免疫球蛋白,批内CV小于2.0％,批间CV小于3.5％,表明该法简便,快速,精密度和准确度高,重复性好。     

Modelling HA protein-mediated interaction between an influenza virus and a healthy cell: pre-fusion membrane deformation.

We present a mathematical model for pre-fusion interaction between an influenza virus and a healthy cell. Our model describes the role played by hemagglutinin (HA) protein clusters in bringing the viral membrane into close contact with the host cell membrane as a first step of the fusion process between the two membranes. The viral membrane is modelled as a lipid bilayer with bending rigidity. Using the calculus of variations, we compute the deformation of the viral membrane under the influence of HA protein clusters. Our numerical results support the hypothesis of dimple formation in the fusion site proposed in the literature. The asymmetric nature of the protein molecules due to various reasons such as tilting is the primary cause for the dimple formation. We discuss the effects of spontaneous curvature, the protein cluster radius, fusion-site size and the bending moment exerted by the protein cluster. We also examine the effects of membrane tension and the presence of a host cell on the dimple shape. Our results support previous experimental observations.     

White matter damage precedes that in gray matter despite similar magnetic resonance imaging changes following cerebral hypoxia-ischemia in neonatal rats

We hypothesized that the cerebral injury produced by hypoxia-ischemia (HI) in neonatal rats would differ in white compared with gray matter as detected histologically or with magnetic resonance (MR) imaging methods. Maps of T₂ and the apparent diffusion coefficient (ADC) of water were acquired in 1-week-old rats at times prior to cerebral HI (right carotid artery occlusion plus 1.5 h of hypoxia), within the last 5–10 min of HI, and 1 h or 24 h after HI. Near the end of HI, ADC decreased and T₂ increased in both cortical gray and subcortical white matter within the cingulum of the HI hemisphere. One hour after HI, ADC partially recovered, but T₂ remained increased and then increased further by 24 h post-HI. In contrast to the similar MR responses in white and gray matter, histological evidence for irreversible cell damage occurred in white matter earlier than in gray matter within the HI hemisphere. At 1 h post-HI, rarefied or disrupted nerve fibers and an increase in TUNEL-positive cells were observed within white matter in the cingulum, whereas neurons within the cortical gray matter appeared normal. By 24 h post-HI, damage was apparent in both white and gray matter. Thus, MR imaging detected acute tissue edema following cerebral HI in both gray and white matter but did not distinguish between the early irreversible tissue injury detected histologically in white but not gray matter in this rather severe model of neonatal encephalopathy.     

Effect on EEG responses of removing ocular artefacts by proportional EOG subtraction

Work undertaken to investigate the effect on EEG responses of ocular artefact removal by proportional electro-oculogram subtraction using the least-squares method is reported. The ocular artefact model and the least-squares approach to estimation of the model parameters and hence of the EEG waveform, including the response, are described. Results are presented to show that the response shapes become modified if ocular artefact removal is implemented recursively. This happens because the response is incorrectly treated as part of the random background EEG. The solution is to incorporate a model of the response within the ocular artefact removal algorithm. The results of tests on simulated data confirm these conclusions. The results of the incorporation of response models in removing ocular artefacts from CNV recordings are presented. Even with modelling recursive ocular artefact removal is found to modify the shape of the CNV, and so reliable results can only be obtained if the removal is implemented nonrecursively. Evidence is given that it is advisable to remove DC levels from the recorded data.     

基于敏感性定理的EIT重构算法仿真研究

为了研究性能更好的EIT图像重构算法，我们对基于敏感性定理的EIT图像重构算法进行了计算机仿真研究，并与几种常用图像重构算法进行比较，提出对基于敏感性定理的EIT图像重构算法的改进措施。     

The structuring of an allergy index based on IgE-mediated skin sensitivity to common environmental allergens

We computed skin-test sensitivity levels in 485 adults puncture-tested with eight standardized, high-quality inhalant allergens tested at single concentrations. In order to quantitate the "average" IgE-mediated skin sensitivity of each subject, we used both nonparametric and parametric statistical methods to generate two "allergy indices" (Allergy Index I and Allergy Index II) based on sensitivity end-point data from the subpopulations of individuals positive to six of the eight allergens. For the 192 skin test-positive subjects, Allergy Index I and Allergy Index II were significantly correlated with each other (rs = 0.98, p less than 0.001) and with the number of positive skin-test reactions (rs congruent to 0.9, p less than 0.001) as well as with log[total serum IgE] (r congruent to 0.4, p less than 0.01). In 102 ragweed-positive subjects, log[specific IgE to ragweed] was significantly correlated with ragweed-specific "ragweed indices I and II" (r congruent to 0.6, p less than 0.01). Furthermore, the average daily symptom scores reported by 14 ragweed-positive subjects during the ragweed pollination season were significantly correlated with ragweed indices I and II (p less than 0.05). We propose the use of Allergy Index II in epidemiologic and genetic studies of allergic phenotypes as well as in clinical decisions for diagnosis and immunotherapeutic intervention.     

No effects of large doses of catecholamines on vascular permeability in isolated blood-perfused dog lungs

Neurogenic pulmonary oedema (NPO) is believed to be induced by intense activation of the sympathetic nervous system, characterized by massive secretion of catecholamines into the blood stream. There is a possibility that NPO is partly the result of increased vascular permeability. However, the mechanism for an increase in pulmonary vascular permeability is not known. The present study was designed to test the hypothesis that large doses of catecholamines increase pulmonary microvascular permeability directly. Adrenaline or noradrenaline (100 and 300 pug) was injected as a bolus into isolated dog lungs perfused with heparinized autologous blood at constant pressure. Adrenaline or noradrenaline produced sustained lung weight loss although both catecholamines increased pulmonary capillary pressure, assessed by double occlusion pressure, by 2–5 mmHg above baseline. Vascular permeability, as measured by the capillary filtration coefficient and the isogravimetric capillary pressure, did not change significantly frombaseline at 30 and 60 min after catecholamine. Finally, the final-to-initial wet lung weight ratio of the catecholamine-treated lungs did not differ from that of saline-injected control lungs. Thus, we conclude that circulating catecholamines, even at supra-physiological doses, do not increase vascular permeability in isolated blood-perfused dog lungs.     

细胞核形态和DNA指数分析在星形细胞瘤分级诊断中的应用

目的 探索自动图像分析系统在胶质瘤分级诊断中的应用。方法 采用自行设计组装的MIPS-I型自动图像分析系统对3个级别星形细胞瘤的细胞核形态和DNA指数(倍体)同时进行原位定量测定。结果 在星形细胞瘤分级诊断中，5项反映核形态的参数诊断正确率为56．3％；代表核DNA改变的7项参数诊断正确率为70．8％；综合应用12项参数诊断正确率为75％。结论 细胞核形态和DNA指数分析可作为星形细胞瘤分级诊断的参考指标之一。     

Normal and homogeneous red blood cell populations over a wide range of hyper-iso-hypotonic media

The volumes of human erythrocytes after rapid and gradual swelling in hypotonic NaCl media were measured using a Coulter Counter Z_B at temperatures of +4°C and +20°C together with potassium leakage, the degree of hemolysis and the ‘returning volume’, i. e., the volume in an isotonic solution to which the cells will return from that in a hypotonic solution. The methodological and systematic errors in the volume measurements were corrected by taking into account the shape dependence of the Coulter Counter and the change in cell population during hemolysis, whereafter the measured cell volume values and the comparison between them become more reliable. The curves for cell volume as an inverse function of osmotic pressure appeared to be non-linear. The slopes were small at first but shoed a rapid increase as the cells approached their maximal volume. The critical hemolytic volume was approx.8% higher at +20°C after both rapid and gradual swelling than at +4°C and approx.4% higher after a gradual swelling as compared with a rapid swelling both at +4°C and +20°C.A decrease in temperature resulted in an increase in the critical osmotic pressure both in rapid and gradual hemolysis, but did not greatly affect the amount of prelytic K⁺ leakage. The critical osmotic pressure was smaller in gradual hemolysis than in rapid hemolysis and the prelytic K⁺ leakage was doubled at both +4°C and +20°C.The shifts in osmotic fragility as a function of temperature may be due to differences in the visco-elastic properties of the cell membrane, but the shifts in osmotic fragility as a function of swelling rate may be connected with differences in potassium leakage and membrane stretch.