脑磁共振灌注成像在大脑中动脉狭窄与闭塞患者中的应用价值分析

目的:研究脑磁共振灌注成像(PWI)在大脑中动脉(MCA)狭窄与闭塞患者中的应用价值。方法:纳入我院从2017年5月~2019年3月收治的单侧MCA狭窄与闭塞患者80例,对所有患者均实施经颅内数字减影血管造影(DSA)以及PWI检查,并将所有患者按照狭窄程度的不同分成轻度/中度组与重度/闭塞组。分析两组患者患侧与健侧大脑半球PWI相关参数,并作相关性分析。此外,分析PWI检查MCA狭窄或闭塞所致脑梗死类型分布情况。结果:DSA诊断结果显示:MCA轻度/中度狭窄患者35例,MCA重度/闭塞患者45例,其中MCA重度/闭塞的PWI检出率为100.00%,显著高于MCA轻度/中度狭窄的80.00%(P<0.05)。MCA轻度/中度组、重度/闭塞组患者患侧大脑半球的平均通过时间(rMTT)、达峰时间(rTTP)均显著高于健侧(均P<0.05)。经Spearman相关性分析可得:MCA患者狭窄程度与患侧大脑半球rMTT、rTTP均呈正相关关系(均P<0.05)。PWI检查结果显示,80例患者共检查出脑梗死患者53例,其中重度/闭塞组脑梗死总检出率以及纹状体内囊区脑梗死检出率分别为82.22%、11.11%,均明显高于轻度/中度组的45.71%、0.00%(均P<0.05)。结论:PWI应用于MCA狭窄与闭塞患者中的价值较高,可作为临床诊断MCA狭窄与闭塞的有效手段之一,值得临床推广应用。     

螺旋CT头颈部血管成像对急性脑梗死患者颈动脉狭窄的诊断价值

目的:探讨螺旋CT头颈部血管成像对急性脑梗死患者颈动脉狭窄的诊断价值。方法:选取2014年1月至2016年1月期间来我院就诊的60例急性脑梗死患者作为观察组,另选同期来我院就诊的非急性脑梗死患者60例作为对照组。两组患者均进行螺旋CT头颈部血管成像检查,比较两组患者的颈动脉狭窄程度及各段血管斑块分布情况,并根据检查结果评价螺旋CT头颈部血管成像对急性脑梗死患者颈动脉狭窄的诊断价值。结果:观察组轻度狭窄与中度狭窄检出率均显著高于对照组(P0.05),重度狭窄与闭塞检出率与对照组比较无统计学差异(P0.05),观察组总检出狭窄率高于对照组(P0.05)。观察组与对照组在颈动脉分叉处、颈总动脉、颈内动脉及颈外动脉均有斑块检出,观察组斑块总检出率为69.4%,显著高于对照组的41.2%(P0.05)。结论:临床上应用128层螺旋CT头颈部血管成像技术对急性脑梗死患者颈动脉狭窄情况可进行有效评估,该方法对患者轻、中度狭窄以及双侧颈动脉斑块检出率更高,在临床诊断及预后防治中具有应用推广价值。     

颈动脉支架置入术后患者认知功能的变化及CT灌注成像技术的疗效评估价值研究

目的:探讨颈动脉狭窄患者在行颈动脉支架置入术后认知功能的变化情况,并分析CT灌注成像(CTP)对手术疗效的评估价值。方法:选取2015年10月到2018年3月在济宁医学院附属日照市人民医院接受治疗的颈动脉狭窄患者80例,其中有症状性颈动脉狭窄患者49例作为有症状组,无症状性颈动脉狭窄患者31例作为无症状组。所有患者均接受颈动脉支架置入手术及CTP检查,采用蒙特利尔认知评估量表(MoCA)、简易智能精神状况量表(MMSE)、搭火柴测验(Stick Test)综合评价颈动脉狭窄患者的术前、术后1周、术后3个月、术后6个月认知功能的变化情况,比较有症状组和无症状组患者的CTP相对灌注参数。结果:术后1周,颈动脉狭窄患者的MoCA总分、视空间/执行能力、注意力、延迟回忆以及MMSE总分、Stick Test总分较术前有所降低(P0.05);术后3个月、术后6个月,颈动脉狭窄患者的MoCA总分、视空间/执行能力、注意力、延迟回忆以及MMSE总分、Stick Test总分较术前有所升高(P0.05)。术前,有症状组的相对血流达峰时间、相对平均通过时间长于无症状组,相对脑血流量低于无症状组(P0.05);术后1周,无症状组的相对血流达峰时间较术前有所缩短,且短于有症状组(P0.05);术后1周,有症状组的相对血流达峰时间、相对平均通过时间较术前有所缩短,相对脑血流量较术前有所升高(P0.05);两组术前、术后1周相对脑血容量比较均无统计学差异(P0.05)。结论:颈动脉支架置入术后患者会出现暂时的、可逆的认知功能恶化,但最终认知功能会得到明显的改善。CTP可发现异常的脑灌注情况,同时能够较好地评价颈动脉支架置入术治疗颈动脉狭窄患者的疗效。     

Cerebral perfusion changes in patients with internal carotid artery stenoses after surgical revascularization

Changes of cerebral perfusion and the condition of collateral blood supply in patients with internal carotid artery stenoses may have a prognostic value for effective blood flow restoration after revascularization of the internal carotid arteries (ICAs). To determine the patterns of cerebral perfusion changes in patients with ICA stenoses before and after surgical treatment, a clinical CT perfusion study of 41 patients with moderate to severe ICA stenoses was performed. Perfusion CT (PCT) had been conducted in 17 patients with moderate ICA stenoses (50–69%) and in 24 patients with severe ICA stenoses (70–99%) 3 times: before intervention (balloon angioplasty with stenting or carotid endarterectomy), on the 3rd to 7th day, and within 1 to 3 months after surgery. Scanning was performed at the level of the basal ganglia and semioval centers. In patients without ICA stenosis (control group of 39 individuals), PCT was conducted once. We found that surgical recanalization of the ICA leads to normalization of the cerebral blood flow parameters in the perfusion area of the middle cranial artery, as evidenced by a decrease of MTT and CBV and an increase of CBF to values comparable to those in the control group. However, blood flow restoration in the anterior and posterior watershed areas, which are known to be mostly affected under chronic hypoperfusion conditions, was observed only in patients with a complete circle of Willis (CW) and moderate ICA stenosis. Therefore, severe stenosis (>70%) and the incomplete CW are the prognostic factors for inadequate blood flow restoration after revascularization in patients with ICA stenoses.     

SPECT 对症状性颅内动脉狭窄支架成形术的疗效评价

目的:通过SPECT脑血流灌注显像,对症状性颅内动脉粥样硬化性狭窄行颅内支架成形术,进行血流动力学的疗效评价。方法:对42例症状性颅内动脉粥样硬化性狭窄(狭窄程度>50%)患者,术前通过SPECT,分为低灌注组和正常灌注组。术后3月复查SPECT,做出血流动力学的疗效评价。通过术前及术后1年mRS评分,比较两组的远期疗效。结果:低灌注组发病症状一般为缺血性卒中,正常灌注组一般为TIA(P<0.01)。低灌注组术后血流灌注较术前改善明显(P<0.01)。正常灌注组复发性TIA的发生率较低灌注组高(P<0.05)。低灌注组术前术后mRS评分有统计学差异(P<0.05)。结论:颅内支架成形术可以明确改善颅内低灌注区的血流灌注,对低灌注组术后缺血事件的预防效果好,并有改善神经功能作用。因此,存在颅内低灌注区的患者更具有颅内支架成形术的手术适应症。     

White Matter Injury Due to Experimental Chronic Cerebral Hypoperfusion Is Associated with C5 Deposition

The C5 complement protein is a potent inflammatory mediator that has been implicated in the pathogenesis of both stroke and neurodegenerative disease. Microvascular failure is proposed as a potential mechanism of injury. Along these lines, this investigation examines the role of C5 in the setting of chronic cerebral hypoperfusion. Following experimental bilateral carotid artery stenosis, C5 protein deposition increases in the corpus callosum over thirty days (p<0.05). The time course is temporally consistent with the appearance of white matter injury. Concurrently, systemic serum C5 levels do not appear to differ between bilateral carotid artery stenosis and sham-operated mice, implicating a local cerebral process. Following bilateral carotid artery stenosis, C5 deficient mice demonstrate decreased white matter ischemia in the corpus callosum when compared to C5 sufficient controls (p<0.05). Further, the C5 deficient mice exhibit fewer reactive astrocytes and microglia (p<0.01). This study reveals that the C5 complement protein may play a critical role in mediating white matter injury through inflammation in the setting of chronic cerebral hypoperfusion.     

老年脑梗死患者急性期全脑血管造影及脑动脉狭窄的危险因素分析

目的:探究老年脑梗死患者急性期全脑血管造影(DSA)及脑动脉狭窄的危险因素。方法:选择2010年1月~2016年9月期间我院收治的562例老年脑卒中患者为研究对象。经DSA造影观察脑血管动脉造影脉狭窄情况,并收集患者一般资料,采用单因素分析及多因素logistics回归分析脑动脉狭窄的危险因素。结果:562例脑卒中患者经DSA检查共发现469例患者出现脑动脉狭窄,中度狭窄301例,血管重度狭窄168例;颅内段发生率显著高于颅外段(P0.05);高龄(OR=1.434,P0.05)、高血压(OR=2.084,P0.05)、糖尿病(OR=2.235,P0.05)及吸烟(OR=2.734,P0.05)是老年脑卒中患者脑血管狭窄的危险因素。结论:DSA显示老年人脑卒中患者多存在脑血管动脉狭窄的发生,年龄、高血压、糖尿病及吸烟是老年脑卒中患者脑血管狭窄的危险因素。     

Upregulation of BACE1 and β-Amyloid Protein Mediated by Chronic Cerebral Hypoperfusion Contributes to Cognitive Impairment and Pathogenesis of Alzheimer’s Disease

Chronic cerebral hypoperfusion (CCH) increases the risk of Alzheimer disease (AD) through several biologically plausible pathways, but the relationship between CCH and the development of AD remains uncertain. To investigate expression of APP, BACE1 and Aβ in the hippocampus of BCCAO rats and study pathophysiological mechanism of AD from CCH. CCH rat model was established by chronic bilateral common carotid artery occlusion (BCCAO). Behavior was evaluated after BCCAO with Morris water maze and open-field task. Expression of Aβ was measured by enzyme linked immunosorbent assay (ELISA). β-Amyloid precursor protein cleavage enzyme 1 (BACE1) and β-amyloid precursor protein (APP) were tested by ELISA, Western blotting and RT-PCR. Cognitive impairment occurred with CCH by Morris water maze test and open-field task. The BACE1 and Aβ level in BCCAO rats was more increased than sham-operation control rats (P < 0.01) but APP had no difference(P > 0.05). The expression of BACE1 and Aβ has no inter-grouop difference in BCCAO rats (P > 0.05). The level of BACE1 and Aβ had positive correlation with cognitive impairment (P < 0.01) while no correlation was observed between APP and cognitive impairment. Chronic cerebral ischemia contributes to cognitive impairment and vascular pathogenesis of Alzheimer’s disease that chronic cerebral hypoperfusion increases BACE1 and Aβ level in brain.     

Ischemic Postconditioning Decreases Cerebral Edema and Brain Blood Barrier Disruption Caused by Relief of Carotid Stenosis in a Rat Model of Cerebral Hypoperfusion

Background and Purpose

Complications due to brain edema and breakdown of blood brain barrier are an important factor affecting the treatment effects of patients with severe carotid stenosis. In this study, we investigated the protective effects of ischemic postconditioning on brain edema and disruption of blood brain barrier via establishing rat model of hypoperfusion due to severe carotid stenosis.

Methods

Wistar rat model of hypoperfusion due to severe carotid stenosis was established by binding a stainless microtube to both carotid arteries. Ischemic postconditioning procedure consisted of three cycles of 30 seconds ischemia and 30 seconds reperfusion. Brain edema was evaluated by measuring cerebral water content, and blood brain barrier permeability was assayed by examining cerebral concentration of Evans'' Blue (EB) and fluorescein sodium (NaF). ELISA was used to analyze the expression of MMP-9, claudin-5 and occludin. The activity and location of MMP-9 was analyzed by gelatin zymography and in situ zymography, respectively. The distribution of tight junction proteins claudin-5 and occludin was observed by immunohistochemistry.

Results

The increased brain water content and cerebral concentration of EB and NaF were suppressed by administration of ischemic postconditioning prior to relief of carotid stenosis. Zymographic studies showed that MMP-9 was mainly located in the cortex and its activity was significantly improved by relief of carotid stenosis and, but the elevated MMP-9 activity was inhibited markedly by ischemic postconditioning. Immunohistochemistry revealed that ischemic postconditioning improved the discontinuous distribution of claudin-5 and occludin. ELISA detected that the expression of up-regulated MMP-9 and down-regulated claudin-5 and occludin caused by carotid relief were all attenuated by ischemic postconditioning.

Conclusions

Ischemic postconditioning is an effective method to prevent brain edema and improve BBB permeability and could be used during relief of severe carotid stenosis.     

Resting Brain Perfusion and Selected Vascular Risk Factors in Healthy Elderly Subjects

Background and Purpose

Both cerebral hypoperfusion and vascular risk factors have been implicated in early aging of the brain and the development of neurodegenerative disease. However, the current knowledge of the importance of cardiovascular health on resting brain perfusion is limited. The aim of the present study was to elucidate the relation between brain perfusion variability and risk factors of endothelial dysfunction and atherosclerosis in healthy aged subjects.

Methods

Thirty-eight healthy subjects aged 50–75 years old were included. Mean global brain perfusion was measured using magnetic resonance phase contrast mapping and regional brain perfusion by use of arterial spin labeling.

Results

Mean global brain perfusion was inversely correlated with caffeine and hematocrit, and positively with end-tidal P_CO2. Furthermore, the mean global brain perfusion was inversely correlated with circulating homocysteine, but not with asymmetric dimethylarginine, dyslipidemia or the carotid intima-media thickness. The relative regional brain perfusion was associated with circulating homocysteine, with a relative parietal hypoperfusion and a frontal hyperperfusion. No effect on regional brain perfusion was observed for any of the other risk factors. A multiple regression model including homocysteine, caffeine, hematocrit and end-tidal P_CO2, explained nearly half of the observed variability.

Conclusion

Both intrinsic and extrinsic factors influenced global cerebral perfusion variation between subjects. Further, the results suggest that the inverse relation between homocysteine and brain perfusion is owing to other mechanisms, than reflected by asymmetric dimethylarginine, and that homocysteine may be a marker of cerebral perfusion in aging brains.     

The role of perfusion computed tomography in the prediction of cerebral hyperperfusion syndrome

Background

Hyperperfusion syndrome (HPS) following carotid angioplasty with stenting (CAS) is associated with significant morbidity and mortality. At present, there are no reliable parameters to predict HPS. The aim of this study was to clarify whether perfusion computed tomography (CT) is a feasible and reliable tool in predicting HPS after CAS.

Methodology/Principal Findings

We performed a retrospective case-control study of 54 patients (11 HPS patients and 43 non-HPS) with unilateral severe stenosis of the carotid artery who underwent CAS. We compared the prevalence of vascular risk factors and perfusion CT parameters including regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF), and time to peak (TTP) within seven days prior to CAS. Demographic information, risk factors for atherosclerosis, and perfusion CT parameters were evaluated by multivariable logistic regression analysis. The rCBV index was calculated as [(ipsilateral rCBV - contralateral rCBV)/contralateral rCBV], and indices of rCBF and TTP were similarly calculated. We found that eleven patients had HPS, including five with intracranial hemorrhages (ICHs) of whom three died. After a comparison with non-HPS control subjects, independent predictors of HPS included the severity of ipsilateral carotid artery stenosis, 3-hour mean systolic blood pressure (3 h SBP) after CAS, pre-stenting rCBV index >0.15 and TTP index >0.22.

Conclusions/Significance

The combination of severe ipsilateral carotid stenosis, 3 h SBP after CAS, rCBV index and TTP index provides a potential screening tool for predicting HPS in patients with unilateral carotid stenosis receiving CAS. In addition, adequate management of post-stenting blood pressure is the most important treatable factor in preventing HPS in these high risk patients.     

Intra-Arterial MR Perfusion Imaging of Meningiomas: Comparison to Digital Subtraction Angiography and Intravenous MR Perfusion Imaging

MethodsStudies were performed in a suite comprised of an x-ray angiography unit and 1.5T MR scanner that permitted intraprocedural patient movement between the imaging modalities. Patients underwent intra-arterial (IA) and intravenous (IV) T2* dynamic susceptibility MR perfusion immediately prior to meningioma embolization. Regional tumor arterial supply was characterized by digital subtraction angiography and classified as external carotid artery (ECA) dural, internal carotid artery (ICA) dural, or pial. MR perfusion data regions of interest (ROIs) were analyzed in regions with different vascular supply to extract peak height, full-width at half-maximum (FWHM), relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and mean transit time (MTT). Linear mixed modeling was used to identify perfusion curve parameter differences for each ROI for IA and IV MR imaging techniques. IA vs. IV perfusion parameters were also directly compared for each ROI using linear mixed modeling.Results18 ROIs were analyzed in 12 patients. Arterial supply was identified as ECA dural (n = 11), ICA dural (n = 4), or pial (n = 3). FWHM, rCBV, and rCBF showed statistically significant differences between ROIs for IA MR perfusion. Peak Height and FWHM showed statistically significant differences between ROIs for IV MR perfusion. RCBV and MTT were significantly lower for IA perfusion in the Dural ECA compared to IV perfusion. Relative CBF in IA MR was found to be significantly higher in the Dural ICA region and MTT significantly lower compared to IV perfusion.     

芸香苷对慢性脑低灌注大鼠认知功能障碍和脑损伤的神经保护作用

目的:研究芸香苷对慢性脑低灌注导致大鼠认知功能障碍和脑损伤的影响。方法:采用双侧颈总动脉结扎法(bilateral common carotid artery occlusion,BCCAO)建立慢性脑低灌注大鼠模型,随机分为4组(n=10):生理盐水治疗模型组、芸香苷治疗模型组、生理盐水治疗假手术组、芸香苷治疗假手术组;连续腹腔注射芸香苷和生理盐水共12周。采用Morris水迷宫评定大鼠学习和记忆能力。采用分光光度法检测脑组织中枢胆碱能相关指标和氧化应激指标。应用免疫组织化学和El ISA方法检测脑组织炎症反应。采用Nissl染色法检测脑组织神经元缺失。结果:芸香苷治疗模型组大鼠的逃脱潜伏期较生理盐水治疗模型组明显减少(P0.01)。与生理盐水治疗模型组相比,芸香苷治疗后显著提高了BCCAO大鼠脑组织中ACh水平(P0.01)和Ch AT活性(P0.01),并降低了ACh E活性(P0.01)。与生理盐水治疗模型组相比,芸香苷治疗模型组显著增加了大鼠脑组织中SOD活性(P0.01)和GPX活性(P0.01),降低了MDA水平(P0.01)和蛋白质羰基化合物水平(P0.01)。芸香苷治疗模型组大鼠海马区GFAP-免疫阳性星型胶质细胞(P0.01)和Iba1-免疫阳性小胶质细胞(P0.01)面积百分比较生理盐水治疗模型组显著减少。芸香苷治疗模型组大鼠海马区正常神经元的数量较生理盐水治疗模型组大鼠显著增加(P0.01)。结论:芸香苷可改善慢性脑低灌注引起的大鼠认知功能障碍和脑损伤。     

Predictors of the Extent of Carotid Atherosclerosis in Patients Treated with Radiotherapy for Nasopharyngeal Carcinoma

Objective

To determine the predictors of the extent of carotid atherosclerosis in patients treated with radiotherapy (RT) for nasopharyngeal carcinoma (NPC).

Methods

The present study investigated 129 post-RT NPC patients. Carotid atherosclerotic parameters, such as carotid intima-media thickness, carotid arterial stiffness and carotid plaque burden (plaque score, the presence of plaque and ≥50% stenosis) were assessed using ultrasonography. The association between carotid atherosclerotic parameters and nine potential predictors, including age, gender, post-RT duration, radiation dose, chemotherapy, diabetes mellitus, hypertension, hypercholesterolemia, and smoking, were determined using multiple regression. The cutoff values of age, post-RT duration and number of cardiovascular risk factors for the presence of carotid plaque or ≥50% carotid stenosis were analyzed using receiver operating characteristic (ROC) curve analysis. Multiple testing was corrected using Benjamini-Hochberg false discovery rate.

Results

Age, post-RT duration and number of cardiovascular risk factors were significantly associated with carotid plaque burden (corrected P value, P_cor<0.05). Age of 44.5 years (sensitivity = 99.2% and specificity = 50%, P_cor<0.01) and post-RT duration of 8.5 years (sensitivity = 75.7% and specificity = 64.3%, P_cor<0.001) were the cutoff values for detecting carotid plaque, while post-RT duration of 13.5 years (sensitivity = 66.7% and specificity = 71.6%, P_cor<0.001) and 1.5 cardiovascular risk factors (sensitivity = 40.7% and specificity = 84.3%, P_cor<0.05) were the cutoff values for screening ≥50% carotid stenosis.

Conclusions

Age, post-RT duration and number of cardiovascular risk factors are significant predictors of carotid atherosclerosis in post-RT NPC patients. Post-RT NPC patients, who are at least 45 years old, with post-RT duration of 9 years or above, and/or have ≥2 cardiovascular risk factors, are more susceptible to carotid atherosclerosis.     

Digital Subtraction Angiography Imaging Characteristics of Patients with Extra–Intracranial Atherosclerosis and Its Relationship to Stroke

To investigate the angiographic characteristics and clinical features in patients with suspected extra–intracranial atherosclerosis in a large cohort of Chinese population. On the basis of digital subtraction angiography characteristics, pathological morphology of extra–intracranial atherosclerosis was divided into tortuosity, kinking, coiling, and stenosis in 2,218 individuals aged 45–89 years. The degree of stenosis was further divided into low-grade (<30 %), intermediate-grade (30–69 %), and high-grade stenosis (≥70 %). Clinical manifestations were divided into transient ischemic attack, cerebral infarction and cerebral hemorrhage. The prevalence of tortuosity and stenosis were significantly higher in the extracranial arterial system than that of intracranial arterial system. The prevalence of tortuosity and kinking were significantly higher on the left side than the right side. The prevalence of mild and moderate stenosis in the internal carotid artery was significantly higher in the left side than the right side. The incidence of cerebral infarction was significantly higher in the internal carotid arterial (ICA) system than the vertebrobasilar arterial (VBA) system. Tortuosity is a common carotid abnormality in the Chinese population. The prevalence of ICA tortuosity is higher than that of VBA. The incidence of cerebral infarction in each atherosclerosis group was significantly higher in ICA than that of VBA. The prevalence of stroke is higher in the ICA system than the VBA system. Kinkings and coilings may not have a clinical significance if these lesions are not associated with atheromatous plaques or carotid stenosis.     

Near-Infrared Transillumination Back Scattering Sounding—New Method to Assess Brain Microcirculation in Patients with Chronic Carotid Artery Stenosis

Purpose

The purpose of the study was to assess the responses of pial artery pulsation (cc-TQ) and subarachnoid width (sas-TQ) to acetazolamide challenge in patients with chronic carotid artery stenosis and relate these responses to changes in peak systolic velocity (PSV), cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and time to peak response (TTP).

Methods

Fifteen patients with carotid artery stenosis ≥90% on the ipsilateral side and <50% on the contralateral side were enrolled into the study. PSV was assessed using colour-coded duplex sonography, CBF, CBV, MTT and TTP with perfusion computed tomography, cc-TQ and sas-TQ with near-infrared transillumination/backscattering sounding (NIR-T/BSS).

Results

Based on the ipsilateral/contralateral cc-TQ ratio after acetazolamide challenge two groups of patients were distinguished: the first group with a ratio ≥1 and the second with a ratio <1. In the second group increases in CBF and CBV after the acetazolamide test were significantly higher in both hemispheres (ipsilateral: +33.0%±8.1% vs. +15.3%±4.4% and +26.3%±6.6% vs. +14.3%±5.1%; contralateral: +26.8%±7.0% vs. +17.6%±5.6% and +20.0%±7.3% vs. +10.0%±3.7%, respectively), cc-TQ was significantly higher only on the ipsilateral side (+37.3%±9.3% vs. +26.6%±8.6%) and the decrease in sas-TQ was less pronounced on the ipsilateral side (−0.7%±1.5% vs. −10.2%±1.5%), in comparison with the first group. The changes in sas-TQ following the acetazolamide test were consistent with the changes in TTP.

Conclusions

The ipsilateral/contralateral cc-TQ ratio following acetazolamide challenge may be used to distinguish patient groups characterized by different haemodynamic parameters. Further research on a larger group of patients is warranted.     

Local blood flow velocities in the carotid body of fetal sheep and newborn lambs

Summary Elastically-suspended microelectrodes were used in the vascularly isolated blood-perfused carotid body of fetal and newborn lambs as well as of 6–7-day-old lambs to measure local blood flow velocities by means of hydrogen clearance. Fetal sheep (n=9) carotid bodies elicited mean local blood velocity values between 0.008 and 0.11 cm·s^–1, whereas newborn lamb carotid bodies (n=7) showed values between 0.008 and 0.067 cm·s^–1 at a perfusion pressure range between 30 and 150 mmHg. The 6–7-day-old lamb carotid bodies (n=5) were characterized by values of 0.003 and 0.049 cm·s^–1 over the same perfusion pressure range. Fetal carotid body values were statistically significantly higher than the values of the 6–7-day-old lamb carotid bodies, whereas the newborn carotid body values showed no significant difference to both other groups. The flow velocity/perfusion pressure relationship peaked at perfusion pressure values between 100 and 150 mmHg in all groups with a reduced steepness in the lamb carotid body. It is concluded that local blood flow velocities in the carotid body are similar to that in other organs, and that after birth local blood flow velocities in the carotid body decrease during the first week of life, probably induced by vasoconstriction, changed blood gas values, and/or increasing shunt flow.Abbreviations significance level - D diffusion coefficient - i.v. intravenous - n number of experiments - PCO ₂ carbon dioxide partial pressure - pH negative logarithm of hydrogen ion concentration - PH ₂ hydrogen partial pressure - Po PH₂ with perfusion - P PH₂ without perfusion - PO ₂ oxygen partial pressure - PP perfusion pressure - r radius     

The Value of the Serum Neurofilament Protein Heavy Chain as a Biomarker for Peri-operative Brain Injury After Carotid Endarterectomy

This prospective study examined the value of serum neurofilament protein levels for detecting peri-operative brain damage following carotid endarterectomy. An ELISA was used for quantification of neurofilament protein heavy chain (NfH^SMI35) levels from patients undergoing endarterectomy for symptomatic (n = 17) and asymptomatic high-grade internal carotid artery stenosis (n = 30). All patients underwent diffusion-weighted brain imaging before and after the procedure. NfH^SMI35 levels were significantly higher in patients with a symptomatic carotid artery stenosis (0.131 ng/ml) if compared to asymptomatic patients (0.055 ng/ml, P = 0.01). However, serum NfH^SMI35 levels were not related to signs of brain ischemia on routine brain imaging techniques. Our pilot data suggests that raised NfH^SMI35 serum levels in patients with symptomatic carotid artery disease may be a sensitive biomarker for diffuse ischemic damage to the CNS. We conclude that NfH^SMI35 failed to qualify as a biomarker for peri-operative brain injury in CEA and factors that may have compromised the validation of this biomarker are discussed and need to be taken into account for the design of further studies.     

Bilateral variation and the evolutionary origin of macroscopic asymmetries

Given that characters exhibiting macroscopic asymmetry have evolved in a wide variety of taxa, heritable variation for bilateral asymmetry must have arisen at some point in their history. The recognition that heritable variation may underlie some statistical asymmetries not only raises concerns about the incautious use of statistical estimates of FA in studies of developmental stability, but it suggests some intriguing questions about the possible evolutionary origins of macroscopic asymmetries. First, we developed an additive model of bilateral variation based on some simple assumptions about the developmental control of bilateral variation. Second, using a new approach for studying statistical asymmetries, we conducted an analysis of bilateral variation in eight metrical traits of a harpacticoid copepod (Tigriopus californicus) to search for novel forms of statistical asymmetries. The model we developed revealed three independent statistical asymmetries of potential evolutionary significance:a) a previously unrecognized form of asymmetry (referred to here asnormal covariant asymmetry),b) antisymmetry, andc) directional asymmetry. Because each pattern of variation would seem to require different amounts and kinds of developmental-genetic information [a- only negative feedback between sides (bilateral inhibition),b- bothbilateral inhibition and average departure from symmetry (bilateral offset),c- bilateral inhibition, bilateral offset, and a consistent overdevelopment of one side or the other (side-bias control)], those requiring less information would seem more likely to represent earlier stages in the evolution of macroscopic asymmetries. Our analysis of bilateral variation inTigriopus revealed no evidence for any form of statistical asymmetry other than fluctuating asymmetry. However, a significant positive covariation between sides, even after correction for body size variation, suggested that factors influencing relative limb length (whether genetic or environmental) affected both sides equally rather than one side at the expense of the other. Finally, we note that certain statistical asymmetries (directional asymmetry, any form of covariant asymmetry) may render characters unreliable for estimating developmental stability because, unlike pure fluctuating asymmetry, they may signal a genetic component to asymmetry variation.     

Relationship between Watershed Infarcts and Recent Intra Plaque Haemorrhage in Carotid Atherosclerotic Plaque

Objective

Watershed infarcts (WSI) are thought to result from hemodynamic mechanism, but studies have suggested that microemboli from unstable carotid plaques may distribute preferentially in watershed areas, i.e., between two cerebral arterial territories. Intraplaque haemorrhage (IPH) is an emerging marker of plaque instability and microembolic activity. We assessed the association between WSI and IPH in patients with recently symptomatic moderate carotid stenosis.

Methods and Results

We selected 65 patients with symptomatic moderate (median NASCET degree of stenosis = 31%) carotid stenosis and brain infarct on Diffusion-Weighted Imaging (DWI) on Magnetic Resonance Imaging (MRI) from a multicentre prospective study. Fourteen (22%) had WSI (cortical, n = 8; internal, n = 4; cortical and internal, n = 2). Patients with WSI were more likely to have IPH than those without WSI although the difference was not significant (50% vs. 31%, OR = 2.19; 95% CI, 0.66–7.29; P = 0.20). After adjustment for degree of stenosis, age and gender, the results remained unchanged.

Conclusion

About one in fifth of brain infarcts occurring in patients with moderate carotid stenosis were distributed in watershed areas. Albeit not significant, an association between IPH - more generally plaque component - and WSI, still remains possible.