Functional magnetic resonance imaging based on changes in vascular space occupancy.

During brain activation, local control of oxygen delivery is facilitated through microvascular dilatation and constriction. A new functional MRI (fMRI) methodology is reported that is sensitive to these microvascular adjustments. This contrast is accomplished by eliminating the blood signal in a manner that is independent of blood oxygenation and flow. As a consequence, changes in cerebral blood volume (CBV) can be assessed through changes in the remaining extravascular water signal (i.e., that of parenchymal tissue) without need for exogenous contrast agents or any other invasive procedures. The feasibility of this vascular space occupancy (VASO)-dependent functional MRI (fMRI) approach is demonstrated for visual stimulation, breath-hold (hypercapnia), and hyperventilation (hypocapnia). During visual stimulation and breath-hold, the VASO signal shows an inverse correlation with the stimulus paradigm, consistent with local vasodilatation. This effect is reversed during hyperventilation. Comparison of the hemodynamic responses of VASO-fMRI, cerebral blood flow (CBF)-based fMRI, and blood oxygenation level-dependent (BOLD) fMRI indicates both arteriolar and venular temporal characteristics in VASO. The effect of changes in water exchange rate and partial volume contamination with CSF were calculated to be negligible. At the commonly-used fMRI resolution of 3.75 x 3.75 x 5 mm(3), the contrast-to-noise-ratio (CNR) of VASO-fMRI was comparable to that of CBF-based fMRI, but a factor of 3 lower than for BOLD-fMRI. Arguments supporting a better gray matter localization for the VASO-fMRI approach compared to BOLD are provided.     

Alterations of G-protein Coupling Function in Phosphoinositide Signalling Pathways of Rat Hippocampus by Ischaemic Brain Injury

The activation of membrane-associated phospholipase C is rapidly and transiently induced in the central nervous system by a variety of stimuli. Ischaemic brain injury is one of the situations that leads to a dramatic increase in polyphosphoinositide (PPI) turnover. In this study, stimulation of PPI hydrolysis by glutamate (500 μM) was measured in hippocampal slices from rats up to 21 days after an ischaemic insult of 30 min. Ischaemia was induced using the four-vessel occlusion method. PPI hydrolysis elicited by glutamate was significantly increased in the slices prepared from ischaemic rats 24 h after reperfusion, the accumulation of inositol phosphates (InsP_s) and inositol 1,4,5-trisphosphate (InsP₃) was 614±74% ( n = 8) and 182±11% ( n = 9) of the basal level respectively. This potentiation was also observed 21 days after ischaemia. Hyper-responsiveness to glutamate was also accompanied by an increase in AIF⁻₄-stimulated formation of [³H]inositol phosphates. In addition, global ischaemia did not change either high-affinity [³H]glutamate binding in hippocampal membranes or the stimulation of PPI hydrolysis by carbachol or noradrenaline in hippocampal slices. The present results suggest that the increased responsiveness to glutamate is the result, at least in part, of functional changes at the G-protein level, and may contribute to the pathophysiology of ischaemic brain injury or to the regenerative phenomena that accompany ischaemic damage.     

城乡学龄前儿童视觉运动整合发育比较分析

为了探讨城乡学龄前儿童视觉运动整合发育的特点,本文采用视觉运动整合发育测试(VMI)对597名城乡集体及散居学龄前儿童进行测查。结果显示:3岁段各组VMI得分比较无差异,而其它年龄段均显示散居儿童低于集体儿童(P相似文献   

Line10肝癌腹水上清的免疫抑制作用

本文研究指出，Ｌｉｎｅ１０肝癌腹水上清具有一定的免疫抑制作用，可致巨噬细胞形态改变并降低其吞噬功能，还可使ＢＡＬＢ／ｃ小鼠的白细胞数量下降。应用Ｏｕｃｈｔｅｒｌｏｎｙ法证明Ｌｉｎｅ１０肝癌腹水上清中存在ｌｉｎｅ１０肝癌细胞的抗原成分。     

白细胞介素—2新的功能位点及其中枢镇痛作用

白细胞介素－２（ＩＬ－２）不仅是重要的免疫调节因子，而且还具有重要的中枢调节作用。本实验以钾离子透入引起大鼠甩尾反应为指标，发现侧脑室注射ＩＬ—２能显著提高动物痛阈，并能被纳洛酮所阻断，表示ＩＬ－２的中枢镇痛作用可能与阿片受体有关。利用基因定位突变技术获得的无免疫活性ＩＬ－２实查体仍具有中枢镇痛作用，表明ＩＬ—２分子上发挥镇痛和免疫调节作用的功能位点是相互独立的。纳洛酮能够阻断ＩＬ—２的中枢镇痛作用，而不能影响ＩＬ—２增殖ＣＴＬＬ－２细胞的作用，提示ＩＬ－２发挥镇痛和免疫调节作用可能通过不同的受体途径。ＩＬ－２分子中第４５位Ｔｙｒ残基突变为Ｖａｌ后，虽仍保留了免疫活性，但丧失了镇痛功能，表示４５位Ｔｙｒ残基是ＩＬ—２发挥中枢镇痛功能的关键残基之一。我们推测ＩＬ—２的镇痛功能位点可能在ＩＬ—２分子中第４５位Ｔｙｒ残基附近区域。     

血清MUC1粘蛋白IRMA及其初步临床应用

建立有效的ＭＵＣ１粘蛋白免疫放射分析法（ＩＲＭＡ），并初步用于乳腺肿瘤的诊断。利用纯化的ＭＵＣ１及其多抗，建立ＭＵＣ１双抗夹心ＩＲＭＡ法，对５５例健康女性、１１例乳腺良性肿瘤、２７例乳腺癌及２８例乳腺癌术后患者进行血清ＭＵＣ１的测定。结果：血清ＭＵＣ１ＩＲＭＡ的灵敏度为０７４ｋＵ／Ｌ；健康女性、乳腺良性肿瘤、乳腺癌及乳腺癌术后患者血清ＭＵＣ１的平均含量分别为７２３±３６７、１７８０±１０５６、３００４±２３８４和３１８４±２４７９ｋＵ／Ｌ；正常值上限为１３５４ｋＵ／Ｌ，假阳性率为１８２％；乳腺肿瘤患者血清ＭＵＣ１水平较健康女性明显提高；乳腺癌患者血清ＭＵＣ１水平高于乳腺良性肿瘤患者，但两者的阳性率（７７８７％和７２７０％）差异无显著性（χ２＝０１５４，Ｐ＞００５）；乳腺癌与乳腺癌术后患者血清ＭＵＣ１水平差异无显著性（ｔ＝－０２２，Ｐ＞００５）。ＭＵＣ１血清水平与肿瘤恶性程度成正相关，对于乳腺癌的诊断具有重要参考价值。     

补体对免疫沉淀的抑制作用与小儿肾脏疾病的关系

以辣根过氧化物酶（PO）和抗-PO作为免疫沉淀中的抗原和抗体，用光电比色法，对78例小儿肾脏疾病血清补体对免疫沉淀的抑制作用（IIPC）进行了研究，并同时检测补体成分C3、C4。结果，正常对照IIPCOD值为0．505±0．085，急性肾小球肾炎（0．137±0．108）显著降低（P＜0．001）；慢性肾小球肾炎（0．470±0．053）改变不明显（P＞0．05）；肾病综合征（0．401±0．038）明显低下（P＜0．05）。IIPC低下的发生率依次为急性肾小球肾炎（83％）、肾病综合征（43％）、慢性肾小球肾炎（32％）。表明小儿肾小球疾病时IIPC大多降低并与疾病的活动性有关。因此认为IIPC低下在肾脏病的发生和发展中起一定作用。     

吲达帕胺对高血压病患者降压作用的临床研究

３４例高血压病患者服国产吲达帕胺后，血压持续缓慢下降，ＴＰＲ显著下降，血浆肾素活性（ＲＡ）、血管紧张素Ⅱ（ＡＴ－Ⅱ）和醛固酮（ＡＤＳ）浓度显著增高，而心率及血儿茶酚爱（ＣＡ）水平无显著变化。治疗４周对全轿Ｃｄ，Ｐｂ，红细胞（ＲＢＣ）及血浆Ｚｎ，Ｃｕ，Ｎａ，Ｋ，Ｍｇ浓度无显著影响。其总疗效为８８．２４％，表明国产吲达帕胺是一种疗效显著而副作用低的降压药物。