急性脑梗死患者脑微出血的发病情况及其危险因素分析

目的探讨急性脑梗死患者脑微出血的发病情况及其危险因素。方法选择急性脑梗死患者75例,男51例,女24例,年龄42～83（64.9±10.8）岁。行头颅CT、磁敏感成像（SWI）检查,依据脑微出血检出的结果分成阳性组（23例）与阴性组（52例）,比较两组的一般资料,探讨脑微出血发病的危险因素。结果SWI检查的检出率比CT检出率高（χ2=27.17,P＜0.05）。阳性组年龄、高血压病、糖尿病患病率均较阴性组高,差异均有统计学意义（均P＜0.05）;两组性别、血脂异常、心房颤动、冠心病、吸烟、饮酒情况比较,差异均无统计学意义（均P＞0.05）。logistic回归分析显示年龄增长、高血压病是脑微出血的独立危险因素（P＜0.05）。结论急性脑梗死患者合并存在脑微出血的比例高,SWI检查是检测脑微出血的敏感方法,年龄大、高血压病与脑微出血的发生密切相关。     

Callistephin inhibits amyloid-β protein aggregation and determined cytotoxicity against cerebrovascular smooth muscle cells as an in vitro model of cerebral amyloid angiopathy

It has been indicated that amyloid β (Aβ) plaques can be accumulated within the basement membranes of cerebrovascular smooth muscle cells (CVSMCs) and stimulate the induction of cerebral amyloid angiopathy (CAA). However, the exact mechanism(s) of which small molecules including callistephin mitigate the formation of Aβ aggregation and associated CAA is not well-understood. Therefore, in the present study, Aβ_1–42 samples in the aggregation buffer were co-incubated for 36 h without or with of callistephin and the protein aggregation features along with the associated cytotoxicity against CVSMCs as the core components of cerebral arterial wall were explored by different biochemical and cellular methods. Fluorescence (ThT, Nile red) and CD techniques indicated the inhibition of Aβ_1–42 fibrillization in the presence of callistephin. Cellular assays revealed that cytotoxicity of Aβ_1–42 samples aged in the aggregation buffer with callistephin was much less against CVSMCs than Aβ_1–42 amyloid alone through regulation of membrane leakage and downregulation of TNF-α and IL-6 at protein level. In conclusion, these data may provide useful information about the possible mechanisms by which callistephin can show its protective effect against CAA.     

Gated magnetic resonance imaging of acute myocardial ischemia in dogs: application of multiecho techniques and contrast enhancement with GD DTPA

ECG gated magnetic resonance images were obtained in six canines prior to and immediately following occlusion of either the LAD or circumflex coronary artery using a surgically placed snare. Multiecho and single-echo acquisition techniques were utilized 0.25 mmol/kg Gd DTPA was injected as an IV bolus 1 hr following coronary artery ligation. In two animals, the region of ischemic myocardium was clearly visualized on multiecho technique without the use of intravenous contrast. The ischemic zone could be best identified on images with a long TE of 120 msec. Contrast enhancement with Gd DTPA enabled visualization of the ischemic myocardium in all six canines. Administration of Gd DTPA, a perfusion agent, improved both detectability and definition of the myocardial lesions.     

Proton spin relaxation studies of fatty tissue and cerebral white matter

Proton spin longitudinal (T1) and transverse (T2) relaxation and proton density studies were carried out on human fatty tissue and bovine white matter, both in the native state and after immersion in D2O. It is concluded that nuclear magnetic resonance signals from fatty tissue result mainly from methyl and methylene protons of hydrocarbons. No contribution from lipid protons could be detected for white matter, although it contains a high percentage of lipids. Imaging experiments, resulting in T1, T2, and proton density maps, support the results obtained with spectroscopic relaxation studies.     

F 2-FDG NMR imaging of the brain in rat

Images of the rat head reflecting glucose utilization were obtained using 2-fluoro-2-deoxy-D-glucose (2-FDG) and ¹⁹F nuclear magnetic resonance (NMR) imaging. Spatial heterogeneity of glucose utilization in the rat head was clearly demonstrated showing significantly higher glucose utilization in the brain as compared to the surrounding tissues. Although the potential adverse effects of the high doses of 2-FDG (400 mg/kg) needed to perform the study preclude immediate application of this technique to clinical quantitative glucose utilization studies, the present study shows potential for future development of glucose utilization imaging by NMR.     

On the sensitivity of ASL MRI in detecting regional differences in cerebral blood flow

Arterial-spin-labeling (ASL) magnetic resonance imaging (MRI) provides a noninvasive tool to measure cerebral blood flow (CBF) and is increasingly used as a surrogate for baseline neural activity. However, the power of ASL MRI in detecting CBF differences between patient and control subjects is hampered by inter-subject variations in global CBF, which are associated with non-neural factors and may contribute to the noise in the across-group comparison. Here, we investigated the sensitivity of this technique and proposed a normalization strategy to better detect such a difference. A “model” situation was employed in which two visual stimuli (i.e. cross fixation and flashing checkerboard) were presented to two groups of subjects to mimic “control” and “patient” groups (N=7 for each group), respectively. It was found that absolute CBF (aCBF) in the occipital lobe in the checkerboard group was 26.0% greater compared to the fixation group, but the level of significance was modest (P=.03). In contrast, when normalizing the CBF with whole-brain CBF or CBF in a reference region [termed relative CBF (rCBF)], the statistical significance was improved considerably (P<.003). For voxel-based analysis, the rCBF indices correctly detected CBF differences in the occipital lobe in the across-group comparison, while aCBF failed to detect any significant cluster using the same statistical threshold. We also performed Monte Carlo simulation to confirm the experimental findings and found that the power improvement was most pronounced when signal-to-noise-ratio is moderate and the underlying CBF difference was small. The simulation also showed that, with the proposed normalization, a detection power of 80% can be achieved using a sample size of about 20. In summary, rCBF is a more sensitive index to detect small differences in CBF, rather than the much-sought-after aCBF, since it reduces data noise caused by inter-subject variations in global CBF.     

Reliability and reproducibility of perfusion MRI in cognitively normal subjects

Arterial spin labeling (ASL) magnetic resonance imaging (MRI) is becoming a popular method for measuring perfusion due to its ability of generating perfusion maps noninvasively. This allows for frequent repeat scanning, which is especially useful for follow-up studies. However, limited information is available regarding the reliability and reproducibility of ASL perfusion measurements. Here, the reliability and reproducibility of pulsed ASL was investigated in an elderly population to determine the variation in perfusion among cognitively normal individuals in different brain structures. Intraclass correlation coefficients (ICC) and within-subject variation coefficients (wsCV) were used to estimate reliability and reproducibility over a period of 1 year. Twelve cognitively normal subjects (75.5±5.3 years old, six male and six female) were scanned four times (at 0, 3, 6 and 12 months). No significant difference in cerebral blood flow (CBF) was found over this period. CBF values ranged from 46 to 53 ml/100 g per minute in the medial frontal gyrus (MFG) and from 40 to 44 ml/100 g per minute over all gray matter regions in the superior part of the brain. Data obtained from the first two scans were processed by two readers and showed high reliability (ICC >0.97) and reproducibility (wsCV <6%). However, over the total period of 1 year, reliability reduced to a moderate level (ICC=0.63–0.74) with wsCVs of gray matter, left MFG, right MFG of 13.5%, 12.3%, and 15.4%, respectively. In conclusion, measurement of CBF with pulsed ASL provided good agreement between inter-raters. A moderate level of reliability was obtained over a 1-year period, which was attributed to variance in slice positioning and coregistration. As such pulsed ASL has the potential to be used for CBF comparison in longitudinal studies.     

Effects of L-Carnitine and its Derivatives – Studies on Isolated Hearts

Summary. The metabolism in the heart prefers long-chain fatty acids to other substrates. L-Carnitine, a co-factor of coenzyme A, plays an essential role in the transport of long-chain fatty acids through the inner mitochondrial membrane. Without carnitine, metabolisation of long-chain fatty acids in the mitochondria is not possible. In addition, acyl groups from acyl-CoA compounds can be transferred to L-carnitine, thus influencing the enzymatic activities of important mitochondrial enzymes.The isolated heart model developed by Langendorff was used to investigate the effects of L-carnitine on the heart. During aerobic perfusion, the hemodynamic parameters of isolated hearts reacted in a very sensitive way to alterations in the external conditions (temperature, preload, composition of the perfusion solution). During postischemic perfusion, recovery of the hearts was also influenced by the composition of the perfusion. The hemodynamic parameters of the reperfused hearts increased markedly if there was a sufficiently high supply of long-chain fatty acids and/or glucose. The insufficient recovery of hearts perfused without glucose and at low fatty acid concentrations could be improved by adding L-carnitine. Determination of carnitine levels in heart tissue found that the heart loses about 30% of its carnitine content during ischemia, and that exogenous carnitine is taken up by the heart during reperfusion. There it effects the restoration of sufficient concentrations of creatine phosphate and ATP, a fact that was confirmed by ³¹P NMR spectroscopy. NMR spectroscopy also established that L-carnitine lessens the harmful effects of ischemia-induced metabolic acidosis.The favourable influence of L-carnitine on the heart in the reperfusion period could be due to a reduction in oxygen radicals (lowering of MDA concentrations during reperfusion, raising of GP_x and SOD activities).The findings of these experiments on isolated hearts as well as the favourable results of two placebo-controlled and double-blind clinical studies (investigating the effects of carnitine in cardiomyopathy patients and the effects of L-carnitine in hemodialysis patients) demonstrate that L-carnitine produces positive therapeutic effects, particularly in heart and circulatory diseases.     

毓神口服液对大鼠前脑缺血海马CA1区神经元的保护作用

为研究毓神口服液对大鼠前脑缺血后海马CA1区神经元的保护作用 ,采用改良的Pulsinelli四血管闭塞法制作前脑缺血模型 ,光镜下观察了CA1区组织病理学变化 ,并计存活锥体细胞密度 (个 mm)。结果表明 ,小剂量组对海马CA1区神经元无明显的保护作用 (与生理盐水组比 ,P >0 0 5 ) ;中剂量、高剂量组对海马CA1区神经元有明显的保护作用 ,且呈剂量依赖性 (缺血 3天各组 ,r=0 877;缺血 7天各组 ,r=0 83 6,P均 <0 0 0 1 )。可见毓神口服液对大鼠前脑缺血后海马CA1区神经元具有明显的保护作用     

MRI in cerebral developmental malformations and epilepsy

Cerebral developmental malformations are increasingly recognized as a major cause of developmental delay and epilepsy. The incidence of these developmental malformations in patients with epilepsy is not known, but epilepsy surgery data suggest that this pathology is commonly seen in children who undergo epilepsy surgery for intractable epilepsy. These malformations can be diagnosed by a combination of clinical, neurophysiological, and imaging techniques. However, imaging techniques such as MRI have been able to provide in vivo recognition of many of these malformations and have contributed to the recognition of specific syndromes. These malformations can be classified on an anatomical basis either into diffuse, unilateral, or generalized. However, a combination of imaging data in conjunction with genetics and embryology may be more appropriate in the future. Further technical developments promise to increase the sensitivity of MRI in detecting these malformations and may help to delineate the possible biology of these disorders.