Vasodilator effects of C-type natriuretic peptide on cerebral arterioles in rats

The vasodilator effects of C-type natriuretic peptide (CNP) were investigated in isolated rat cerebral arterioles. CNP caused dose-dependent vasodilation, maximally by 10.0±2.2% at 10⁻⁶ M. The median effective concentration (EC₅₀) was 5.2×10⁻¹⁰ M. In contrast, atrial natriuretic peptide and B-type natriuretic peptide, other members of the natriuretic peptide family, produced little or no vasodilation. Pretreatment with methylene blue (10⁻⁴ M) abolished CNP-induced vasodilation, whereas pretreatment with N^G-monomethyl-

Full-size image

-arginine or indomethacin did not inhibit vasodilation. Thus, CNP is suggested to cause significant vasodilation in cerebral arterioles via a cyclic guanosine monophosphate-dependent mechanism. © 1997 Elsevier Science B.V. All rights reserved.     

重型颅脑损伤持续颅内压及脑灌注压监护与预后关系

作者对５０例重型颅脑损伤患者（ＧＣＳ３－８分），及５０例伤情与诊断和手术方式基本相似的另一组患者进行颅内压（ＩＣＰ）与脑灌注压（ＣＣＰ）连续监测对比研究。结果表明，监护组除８例ＩＣＰ压力＜２．００ｋＰａ，ＣＰＰ＞９．３３ｋＰａ外，余４２例均有不同程度ＩＣＰ增高与ＣＰＰ降低。这些患者分别为创伤性颅内血肿、广泛性脑挫裂伤、继发性脑水肿或脑肿胀等，均采取积极的手术及综合治疗。死亡率为１４％。非监护组治疗方法与监护组相同，预后较差且并发症多，死亡率为２８％。作者认为，对重型颅脑损伤患者施行连续ＩＣＰ、ＣＰＰ监护，是降低并发症和死亡率，提高疗效的有力措施，具有重要的临床应用价值。     

MRI of the brain in chronic carbon monoxide poisoning

We examined 13 patients with chronic carbon monoxide (CO) poisoning by magnetic resonance imaging (MRI); all of them had been in an explosion in a coal mine 25 years previously. Symmetrical globus pallidus lesions were observed in 12, as was degeneration of the white matter, with focal cortical atrophy. The temporal parietal and occipital lobes were usually affected, the parietooccipital region being the most frequently and extensively damaged. Of the 12 patients with white matter degeneration 7 had definitely asymmetrical cortical and subcortical lesions. There were 6 patients with dilated temporal horns, probably due to atrophy of the hippocampal gyri. A history of CO inhalation and an awareness of the typical distributions of lesions are important for recognition of the effects of CO poisoning, especially when patients are in the chronic stage.     

Contrast agents in functional MR imaging

Contrast agents have greatly expanded the role of MR imaging (MRI) to allow assessment of physiologic, or “functional,” parameters. Although activation mapping generally does not require contrast agents, other forms of functional MRI, including mapping of cerebral hemodynamics (eg, perfusion imaging), are best done with the use of contrast agents. Serial echo planar images are obtained after bolus injection of lanthanide chelates. Application of susceptibility contrast physics and standard tracer kinetic principles permits generation of relative cerebral blood volume maps. Deconvolution of cerebral blood flow and mean transit time parameters is also possible within technical limitations. By using diffusion and perfusion pulse sequences, an imaging correlate to the ischemic penumbra can be identified. Functional MRI perfusion imaging of intraaxial tumors is analogous to positron emission tomography for delineation of metabolic activity, yet may be even more sensitive to neovascularity and possesses improved image quality. Clinical applications include biopsy site selection and postirradiation follow-up. Further improvements in data analysis and map generation techniques may improve diagnostic accuracy and utility.     

老年脑梗死与血浆纤维蛋白原、血小板聚集率相关性研究

目的 探讨老年脑梗死和血浆纤维蛋白原、血小板聚集率的关系。方法 对2124名老年个体进行面对面问卷调查，按脑梗死诊断标准分为脑梗死组非脑梗死组，在脑梗死组的333人中，进行血浆纤维蛋白原、血小板聚集率化验，在非脑梗死组中完全随机按1：2抽取666人作为对照，亦进行血浆纤维蛋白原、血小板聚集率检查，行t检验。脑梗死的相关因素应用Logistic回归分析。结果 脑梗死组的血浆纤维蛋白原、血小板聚集率水平高于非脑梗死组。结论 老年脑梗死患者的血浆纤维蛋白原水平增高，血小板聚集功能增强。     

Expectant management of deep cerebral venous thrombosis with intraventricular hemorrhage

Limited randomized clinical trial data favor the use of anticoagulation in patients with cerebral venous thrombosis. We present a patient with deep cerebral venous thrombosis in whom anticoagulation was withheld because of coexistent intraventricular hemorrhage. She had a benign clinical course without anticoagulation, suggesting that close observation may be a management option in these patients.     

Diffusion-weighted magnetic resonance imaging for demonstration of cerebral infarcts

Summary Forty-one patients demonstrating clinical symptoms for cerebral infarction were investigated by magnetic resonance imaging with diffusion-weighted echo-planar imaging (DWI) and T2-weighted imaging (T2WI). In 8 patients only DWI showed the cerebral lesions clearly. One patient with positive DWI and T2WI suffered from HSV encephalitis. DWI is superior to T2WI in assessment of small cortical infarcts and cerebral infarction in patients with preexisting vascular lesions. DWI is not specific, so other causes like cerebral hematoma and encephalitis have to be considered.      

Reduction in Internal Carotid Arterial Blood Flow Velocity in Children During Antiepileptic Drug Therapy with Clinical Dosages

Summary: We studied the effect of antiepileptic drugs (AEDs) on internal carotid artery (ICA) blood flow velocity, as an index of total cerebral blood flow (CBF). The subjects were 45 newly diagnosed children with febrile convulsion or epilepsy who were seizure-free for a period long enough not to affect the results. They had no neurologic deficit, received fixed monotherapy, and were examined by a noninvasive Doppler ultrasound method, in comparisonwith 13 age-matched normal volunteers with no AED. In 30 patients, the measurements were performed before and after AED administration [10 with phenobarbital (PB), 10 with carbamazepine (CBZ), and 10 with valproate (VPA)], and performed before and after AED discontinuation in the remaining 15 patients (all with PB). Normal volunteers underwent the two consecutive examinations with a mean interval equal to that of the entire patient group, and there was no difference in velocity values between the measurements. In patients receiving CBZ or VPA, a significant reduction was noted in blood flow velocity after drug administration. Although velocity values in the patients receiving PB did not change after drug administration, they were significantly increased after complete discontinuation. In the present study, a slight but significant reduction in CBF caused by AED administration at therapeutic doses in children was suggested.     

富氧气体防护下暴发性缺氧大鼠大脑超微病理变化

目的 从亚细胞水平观察大鼠在12 000m高度暴发性缺氧及富氧气体防护时大脑顶叶皮质组织超微结构变化，为高空暴发性缺氧的防护和治疗提供理论依据。方法 将24只雄性Wistar大鼠随机分为地面对照组、3000m对照组、12000m暴发性缺氧组、12000m吸90％富氧气体防护组、12000m吸100％氧气防护组、12000m吸50％富氧气体防护组，每组4只。于低压舱内暴露于12000m高度30min，然后将动物即刻处死，取大脑顶叶皮质层组织，制成切片，透射电镜下观察。结果与地面对照组相比，随着吸氧浓度的降低，实验组缺氧程度加重，主要表现为脑组织神经细胞、神经胶质细胞结构模糊不清，核及胞质内线粒体、内质网扩张，突触小泡减少等，以12000m暴发性缺氧组及吸50％氧气防护组明显。结论 吸100％和吸90％富氧气体防护效果是理想的，与地面对照组和3000m对照组的结果无明显差别。     

依托咪酯对大鼠皮层、海马脑片缺氧复氧损伤的保护作用

目的观察依托眯酯对大鼠皮层、海马脑片缺氧复氧损伤的保护作用及其机制。方法雄性SD大鼠10只,体重90-100 g,制备大脑皮质和海马脑片,随机分为对照组、缺氧复氧组、3 μmol ·L-1依托咪酯组、6μmol·L-1依托咪酯组、15 μmol·L-1依托咪酯组和6 μmol·L-1依托咪酯+γ-氨基丁酸 A(GABAA)受体拮抗剂Picrotoxin 50 μmol·L-1组。各组脑片缺氧10 min复氧120 min时,测定经三苯基氯化四唑氮染色的吸光度(A490),Fluo-3荧光染色后计算细胞内Ca2+浓度。结果缺氧复氧可导致大脑皮层、海马A490降低,细胞内Ca2+浓度升高,不同浓度依托咪酯可减弱缺氧复氧导致的上述改变,以 6 μmol·L-1依托咪酯的效果较好,且此作用可被GABAA受体拮抗剂完全拮抗。结论依托咪酯对大鼠皮层、海马脑片缺氧复氧损伤有一定的保护作用,可能通过GABAA受体介导,并降低Ca2+负荷有关。