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51.
Elizabeth R Seaquist Wei Chen Luke E Benedict Kamil Ugurbil Jae-Hwan Kwag Xiao-Hong Zhu Charles A Nelson 《Journal of cerebral blood flow and metabolism》2007,27(1):154-160
Functional magnetic resonance imaging (fMRI) based on blood oxygen level-dependent (BOLD) contrast has become an invaluable tool in the assessment of in vivo neuronal activation. Quantification of the BOLD response is determined by the hemodynamic and metabolic changes that occur in response to brain stimulation. However, these changes may vary by changes in insulin, a hormone known to be vasoactive in some tissues. To determine if insulin has an effect on fMRI, we measured the BOLD response to a visual stimulus in five normal volunteers in which insulin was first suppressed and then brought to a high physiological concentration. In addition, we also examined the effect of insulin on activation of the visual cortex as measured by the visual-evoked potential (VEP). We found that the BOLD response measured in the presence of insulin (serum insulin=236+/-29 pmol/L) was significantly lower (P<0.001) than that measured in its absence (serum insulin=8+/-2 pmol/L). Insulin was without effect on P100 amplitude or latency acquired in the presence or absence of insulin in 28 subjects using the same stimulus as that used for the fMRI experiments. Our observations suggest that insulin may have effects on cerebral blood flow and/or metabolism that affect the BOLD signal that are independent of its effects on neuronal activation identified by event related potentials (ERP). These findings highlight the complexity that must be considered when interpreting differences in fMRI responses between groups of subjects that differ in insulin concentration and/or insulin sensitivity. 相似文献
52.
We present a correspondence-based system for visual object recognition with invariance to position, orientation, scale and deformation. The system is intermediate between high- and low-dimensional representations of correspondences. The essence of the approach is based on higher-order links, called here maplets, which are specific to narrow ranges of mapping parameters (position, scale and orientation), which interact cooperatively with each other, and which are assumed to be formed by learning. While being based on dynamic links, the system overcomes previous problems with that formulation in terms of speed of convergence and range of allowed variation. We perform face recognition experiments, comparing ours to other published systems. We see our work as a step towards a reformulation of neural dynamics that includes rapid network self-organization as essential aspect of brain state organization. 相似文献
53.
以健康Wistar大白鼠为材料,对微波快速内源性过氧化物酶染色与灌注法显示微血管的方法进行了对比研究。结果,过氧化物酶组织化学法具有不用灌注,操作简单,所用时间短,对血管无扩张、破裂等人为改变的特点,保持了微血管真实的自然形态和管径大小,可以定量或半定量地判定组织器官活体时的血液循环状况。可以用于人及动物的大脑、脊髓、皮肤、耳及食管等组织内微血管形态学研究和定量分析。并对过氧化物酶显示微血管的原理和微波辐射促进染色的原理及特点进行了分析、讨论。 相似文献
54.
We determined the serum levels of the creatine kinase B subunit (CK-B) by an enzyme immunoassay method in patients with renal cell carcinoma (RCC) and benign renal diseases. Eighteen of 76 patients with RCC (24%) had elevated serum CK-B levels. The positive rates were 29% in stage I, 13% in stage II, 15% in stage III, and 27% in stage IV. In all 9 patients whose serum CK-B levels were serially measured and had been elevated before operation, the CK-B levels were reduced to the normal range after nephrectomy. These findings indicate that serum CK-B is a useful biomarker for monitoring the clinical course for a limited number of RCC patients, but is not a marker for diagnosis and staging. Concentrations of CK-B in RCC tissues were significantly lower than those of normal kidney. A high rate of cell turnover in tumor tissues might entail the higher level of serum CK-B in patients with RCC. 相似文献
55.
格林—巴利综合征患者血清和脑脊液中的抗硫脂抗体 总被引:5,自引:1,他引:4
探讨抗硫脂抗体与格林-巴利综合征(GBS)的关系。方法采用固相酶联免疫吸附法对急性期GBS患者血清和脑脊液(CSF)中抗硫脂IgG和IgM抗体进行检测。结果GBS患者血清和CSF中抗硫脂IgG及IgM抗体的阳性率均明显高于正常对照组;血清中抗硫脂IgM抗体滴度与标本收集时患者发病天数呈负相关(P<0.05),而血清中抗硫脂IgG抗体滴度与临床分级(P<0.01)、CSF中抗硫脂IgG抗体滴度(P<0.01)呈正相关;血清中抗硫脂IgG或IgM阳性的GBS患者,体检时有不同程度的感觉障碍患者为56%,而血清中抗硫脂抗体阴性患者仅为16%,两者之间差异有显著意义(P<0.05)。结论抗硫脂抗体可能在GBS的病理过程中起重要作用 相似文献
56.
57.
58.
神经梅毒的临床特征与诊断分析 总被引:34,自引:2,他引:32
目的:分析神经梅毒的分型和临床特征及提供早期诊断依据。方法:回顾性分析经临床和实验室检查确诊的18例神经梅毒病人的有关临床资料。结果:神经梅毒的临床特征包括:(1)急性、亚急性起病为主;(2)临床以间质型,尤其是以脑卒中起病常见,症状元特异性;(3)血清学检查以梅毒螺旋体血凝试验(TPHA)及快速血浆反应素试验(RPR)特异性较高;(4)脑脊液检查表现为压力增高(42.9%)、蛋白增高(81.2%)及细胞数增高(56.3%);(5)头颅CT、MRI表现与高血压、动脉硬化所致脑梗死不同,为多发、散在病灶。结论:神经梅毒早期误诊率高,临床表现与分型密切相关,实验室及影像学检查是诊断的重要依据。 相似文献
59.
Summary. A prevalence study of Ureaplasma urealyticum (UU) infection of the male genital tract was carried out in Shanghai between March 1992 and June 1995. Significantly higher frequency of UU infection was found among infertile males (549/1416) as compared to fertile controls (34/375). Examination of 8 specimens each from infertile men and fertile subjects by electron microscopy, immunogold and immunofluorescence techniques, demonstrated adhesion of Ureaplasma urealyticum to the membrane of spermatozoa and exfoliated germ cells. In addition, gold particles on Ureaplasma urealyticum were found to be adhered to the sperm surface in 4 of the 8 samples. Strong specific anti-UU fluorescence was detected in 6 of 8 samples, mainly on the midpieces and post-acrosomal regions of the spermatozoa.
To further study the effects of Ureaplasma urealyticum on fertility, 47 male Sprague-Dawley (SD) rats were infected artificially with Ureaplasma urealyticum serotype 8 (T960). Morphological changes in the seminiferous tubules were observed 3–5 weeks after inoculation in the sacrificed animals. Dramatic impairment of spermatogenesis of both testes was found in 11 rats. Mating experiment confirmed infertility in 12 of 40 rats. Offsprings of the infected rats were significantly smaller than those of controls in terms of prenatal weights and birthweights. 相似文献
To further study the effects of Ureaplasma urealyticum on fertility, 47 male Sprague-Dawley (SD) rats were infected artificially with Ureaplasma urealyticum serotype 8 (T960). Morphological changes in the seminiferous tubules were observed 3–5 weeks after inoculation in the sacrificed animals. Dramatic impairment of spermatogenesis of both testes was found in 11 rats. Mating experiment confirmed infertility in 12 of 40 rats. Offsprings of the infected rats were significantly smaller than those of controls in terms of prenatal weights and birthweights. 相似文献
60.
在回顾《内经》、《难经》关于“气口独为五脏主”论述的基础上,指出:气口诊脉可测知全身气血盛衰、胃气的强弱、经脉的变动、五脏六腑的功能状态,以及外邪入侵后,人体疾病的阴阳、表里、虚实、寒热等变化。强调“气口诊脉”至今仍是中医诊脉的主要方法之一。 相似文献