维普中文期刊产品整合服务
2434篇 您的检索式:作者名="Spence"
    题名 作者 年代 出处 被引量
1Cardioembolic stroke:everything has changed显示文摘Historically,because of the difficulty of using warfarin safely and effectively,many patients with cardioembolic stroke who should have been anticoagulated were instead given ineffective antiplatelet therapy(or no antithrombotic therapy).With the arrival of new oral anticoagulants that are not significantly more likely than aspirin to cause severe haemorrhage,everything has changed.Because antiplatelet agents are much less effective in preventing cardioembolic stroke,it is now more prudent to anticoagulate patients in whom cardioembolic stroke is strongly suspected.Recent advances include the recognition that intermittent atrial fibrillation is better detected with more prolonged monitoring of the cardiac rhythm,and that percutaneous closure of patent foramen ovale(PFO)may reduce the risk of stroke.However,because in most patients with stroke and PFO the PFO is incidental,this should be reserved for patients in whom paradoxical embolism is likely.A high shunt grade on transcranial Doppler saline studies,and clinical clues to paradoxical embolism,can help in appropriate selection of patients for percutaneous closure.For patients with atrial fibrillation who cannot be anticoagulated,ablation of the left atrial appendage is an emerging option.It is also increasingly recognised that high levels of homocysteine,often due to undiagnosed metabolic deficiency of vitamin B_(12),markedly increase the risk of stroke in atrial fibrillation,and that B vitamins(folic acid and B_(12))do prevent stroke by lowering homocysteine.However,with regard to B_(12),methylcobalamin should probably be used instead of cyanocobalamin.Many important considerations for judicious application of therapies to prevent cardioembolic stroke are discussed.J David Spence 2018Stroke & Vascular Neurology2018,3,2:10
2How to identify which patients with asymptomatic carotid stenosis could benefit from endarterectomy or stenting显示文摘Offering routine carotid endarterectomy(CEA)or carotid artery stenting(CAS)to patients with asymptomatic carotid artery stenosis(ACS)is no longer considered as the optimal management of these patients.Equally suboptimal,however,is the policy of offering only best medical treatment(BMT)to all patients with ACS and not considering any of them for prophylactic CEA.In the last few years,there have been many studies aiming to identify reliable predictors of future cerebrovascular events that would allow the identification of patients with high-risk ACS and offer a prophylactic carotid intervention only to these patients to prevent them from becoming symptomatic.All patients with ACS should receive BMT.The present article will summarise the evidence suggesting ways to identify these high-risk asymptomatic individuals,namely:(1)microemboli detection on transcranial Doppler,(2)plaque echolucency on Duplex ultrasound,(3)progression in the severity of ACS,(4)silent embolic infarcts on brain CT/MRI,(5)reduced cerebrovascular reserve,(6)increased size of juxtaluminal hypoechoic area,(7)identification of intraplaque haemorrhage using MRI and(8)carotid ulceration.The evidence suggests that approximately 10%-15%of patents with asymptomatic stenosis might benefit from intervention;this will become more clear after publication of ongoing studies comparing stenting or endarterectomy with best medical therapy.In the meantime,no patient should be offered intervention unless there is evidence of high risk of ipsilateral stroke,from modalities such as those discussed here.Kosmas I Paraskevas Frank J Veith J David Spence 2018Stroke & Vascular Neurology2018,3,2:10
3Blood pressure gradients in cerebral arteries:a clue to pathogenesis of cerebral small vessel disease显示文摘rationale The role of hypertension in cerebral small vessel disease is poorly understood.At the base of the brain(the‘vascular centrencephalon’),short straight arteries transmit blood pressure directly to small resistance vessels;the cerebral convexity is supplied by long arteries with many branches,resulting in a drop in blood pressure.Hypertensive small vessel disease(lipohyalinosis)causes the classically described lacunar infarctions at the base of the brain;however,periventricular white matter intensities(WMIs)seen on MRI and WMI in subcortical areas over the convexity,which are often also called‘lacunes’,probably have different aetiologies.Objectives We studied pressure gradients from proximal to distal regions of the cerebral vasculature by mathematical modelling.Methods and results Blood flow/pressure equations were solved in an Anatomically Detailed Arterial Network(ADAN)model,considering a normotensive and a hypertensive case.Model parameters were suitably modified to account for structural changes in arterial vessels in the hypertensive scenario.Computations predict a marked drop in blood pressure from large and medium-sized cerebral vessels to cerebral peripheral beds.When blood pressure in the brachial artery is 192/113 mm Hg,the pressure in the small arterioles of the posterior parietal artery bed would be only 117/68 mm Hg.In the normotensive case,with blood pressure in the brachial artery of 117/75 mm Hg,the pressure in small parietal arterioles would be only 59/38 mm Hg.conclusion These findings have important implications for understanding small vessel disease.The marked pressure gradient across cerebral arteries should be taken into account when evaluating the pathogenesis of small WMIs on MRI.Hypertensive small vessel disease,affecting the arterioles at the base of the brain should be distinguished from small vessel disease in subcortical regions of the convexity and venous disease in the periventricular white matter.Pablo J Blanco Lucas O Müller J David Spence 2017Stroke & Vascular Neurology2017,2,3:9
4A CFD parametric study of geometrical variations on the pressure pulsations and performance characteristics of a centrifugal pump显示文摘R. Spence J. Amaral-Teixeira 2008Computers and Fluids2008,,6:5
5Controlling resistant hypertension显示文摘Resistant hypertension(failure to achieve target blood pressures with three or more antihypertensive drugs including a diuretic)is an important and preventable cause of stroke.Hypertension is highly prevalent in China(>60%of persons above age 65),and only~6%of hypertensives in China are controlled to target levels.Most strokes occur among persons with resistant hypertension;approximately half of strokes could be prevented by blood pressure control.Reasons for uncontrolled hypertension include(1)non-compliance;(2)consumption of substances that aggravated hypertension,such as excess salt,alcohol,licorice,decongestants and oral contraceptives;(3)therapeutic inertia(failure to intensify therapy when target blood pressures are not achieved);and(4)diagnostic inertia(failure to investigate the cause of resistant hypertension).In China,an additional factor is lack of availability of appropriate antihypertensive therapy in many healthcare settings.Sodium restriction in combination with a diet similar to the Cretan Mediterranean or the DASH(Dietary Approaches to Stop Hypertension)diet can lower blood pressure in proportion to the severity of hypertension.Physiologically individualised therapy for hypertension based on phenotyping by plasma renin activity and aldosterone can markedly improve blood pressure control.Renal hypertension(high renin/high aldosterone)is best treated with angiotensin receptor antagonists;primary aldosteronism(low renin/high aldosterone)is best treated with aldosterone antagonists(spironolactone or eplerenone);and hypertension due to overactivity of the renal epithelial sodium channel(low renin/low aldosterone;Liddle phenotype)is best treated with amiloride.The latter is far more common than most physicians suppose.J David Spence 2018Stroke & Vascular Neurology2018,3,2:4
6Mass transport deposits and processes in the north slope of the Xisha Trough,northern South China Sea显示文摘Triple mass-transport deposits(MTDs) with areas of 625, 494 and 902 km2, respectively, have been identified on the north slope of the Xisha Trough, northern South China Sea margin. Based on high-resolution seismic reflection data and multi-beam bathymetric data, the Quaternary MTDs are characterized by typical geometric shapes and internal structures. Results of slope analysis showed that they are developed in a steep slope ranging from 5° to 35°. The head wall scarps of the MTDs arrived to 50 km in length(from headwall to termination). Their inner structures include well developed basal shear surface, growth faults, stepping lateral scarps, erosion grooves, and frontal thrust deformation. From seismic images, the central deepwater channel system of the Xisha Trough has been filled by interbedded channel-levee deposits and thick MTDs. Therefore, we inferred that the MTDs in the deepwater channel system could be dominated by far-travelled slope failure deposits even though there are local collapses of the trough walls. And then, we drew the two-dimensional process model and threedimensional structure model diagram of the MTDs. Combined with the regional geological setting and previous studies, we discussed the trigger mechanisms of the triple MTDs.QIN Zhiliang WU Shiguo WANG Dawei LI Wei GONG Shaojun MI Lijun SPENCE George 2015Acta Oceanologica Sinica2015,34,9:4
7China Stroke Statistics 2019: a wealth of opportunities for stroke prevention显示文摘The China Stroke Statistics published in this issue of the journal1 represent an enormous undertaking.It included data on 3010204 patients who had a stroke admitted in 2018 to 1853 tertiary care hospitals and compiled data from multiple sources on stroke and stroke risk factors in China.The authors and the huge team of workers who must have compiled the statistics are to be commended on this enormous effort.In the report is a wealth of data on what is wrong in China to cause such a high risk of stroke but also a wealth of opportunity to make a difference.The reason this is so important is that~80%of strokes are preventable.J David Spence 2020Stroke & Vascular Neurology2020,5,3:3
8Prevalence and outcomes of anemia in surgery: a systematic review of the literature显示文摘Aryeh Shander Kevin Knight Robert Thurer John Adamson Richard Spence 2004The American Journal of Medicine2004,,7:2
9Exohiss wave enhancement following substorm electron injection in the dayside magnetosphere显示文摘Exohiss is a low-frequency structureless whistler-mode emission potentially contributing to the precipitation loss of radiation belt electrons outside the plasmasphere. Exohiss is usually considered the plasmaspheric hiss leaked out of the dayside plasmapause.However, the evolution of exohiss after the leakage has not been fully understood. Here we report the prompt enhancements of exohiss waves following substorm injections observed by Van Allen Probes. Within several minutes, the energetic electron fluxes around 100 keV were enhanced by up to 5 times, accompanied by an up to 10-time increase of the exohiss wave power. These substorm-injected electrons are shown to produce a new peak of linear growth rate in the exohiss band(< 0.1 f_(ce)). The corresponding path-integrated growth rate of wave power within 10° latitude of the magnetic equatorial plane can reach 13.4, approximately explaining the observed enhancement of exohiss waves. These observations and simulations suggest that the substorm-injected energetic electrons could amplify the preexisting exohiss waves.ZhongLei Gao ZhenPeng Su FuLiang Xiao HuiNan Zheng YuMing Wang Shui Wang H. E. Spence G.D. Reeves D. N. Baker J. B. Blake H.O. Funsten 2018Earth and Planetary Physics2018,2,5:2
10Multisensory flavor perception: Assessing the influence of fruit acids and color cues on the perception of fruit-flavored beverages显示文摘Massimiliano Zampini Emma Wantling Nicola Phillips Charles Spence 2007Food Quality and Preference2007,,3:2
11Association of homocysteine and smoking with cerebral microemboli in patients with mechanical heart valves:a transcranial Doppler study显示文摘Objectives Microembolic signals(MES)on transcranial Doppler(TCD)predict stroke and cognitive decline.Plasma levels of total homocysteine(tHcy),a prothrombotic factor,are higher in patients with microemboli in carotid stenosis and in patients with paradoxical embolism.In this study we assessed the association between the level of tHcy and the number of MES in patients with mechanical heart valves(MHVs).Methods TCD monitoring was performed to detect MES before and after breathing 100% oxygen and repeated every 2-4 weeks up to six times.results Twenty-five patients with MHVs(mean age:63.60±10.15 years)participated in this study;15 were men(66.47±7.25 years)and 10 were women(59.30±12.60 years).In total,there were 126 study visits.In multiple regression,higher tHcy was associated with more MES in both preoxygenation(OR 1.34(95%CI 1.07 to 1.68,P=0.009))and postoxygenation(OR 1.40(95% CI 1.07 to 1.83,P=0.01))phases.Current smoking and the length of time between the operation and monitoring also correlated with a higher number of MES before and after breathing oxygen,particularly in women.conclusions Higher tHcy and smoking were associated with a higher MES count in both preoxygenation and postoxygenation phases.Because smoking can be stopped and hyperhomocysteinaemia is treatable,these are clinically important findings.Alicia Mattia M Reza Azarpazhooh Claudio Munoz Chrysi Bogiatzi Mackenzie A Quantz J David Spence 2017Stroke & Vascular Neurology2017,2,4:2
12神奇的纳米技术显示文摘从来没有哪一个30年像过去30年那样经历了如此之长的技术发展历程。当然是指科学和技术领域所获成就的常增曲线。Bill Spence 戴雪梅 2000世界科学2000,22,5:2
13Investigation into pressure pulsations in a centrifugal pump using numerical methods supported by industrial tests显示文摘R. Spence J. Amaral-Teixeira 2007Computers and Fluids2007,,6:2
14The behaviour and ecology of the zebrafish, Danio rerio 显示文摘Spence R Gerlach G Lawrence C 2008Biol Rev Camb Philos Soc2008,83,:1
15Carpal tunnel syndrome显示文摘Aroori S Spence RA 2008Ulster Med J2008,77,1:1
16Job Market Signaling显示文摘Spence M 1973The Quarterly Journal of Economics1973,87,3:1
17Content - Centered Collaboration Spaces in the Cloud 显示文摘ERICKSON J S SPENCE S RHODES M 2009IEEE Internet Computing2009,13,5:1
18Perioperative fluid management:currentconsensus and controversies显示文摘Yeager MP Spence BC 2006Semin Dial2006,19,6:1
19The Forgotten Stakeholder? Ethics and Social Respon- sibility in Relation to Competitors 显示文摘Spence L J Coles A Harris L 2001Business and Society Review2001,106,4:1
20Changes in the size and shape of the human mandible in Britain显示文摘Moore WJ Lavelle CLB Spence TF 1968British Dental Journal1968,125,:1
返回顶部 每页显示:
共122页 首页 上一页 第1页 下一页 末页 /122 跳转

网站首页 | 关于我们 | 联系我们 | 产品服务 | 客服中心 | 广告服务 | 版权声明 | 网站联盟 | 友情链接 | 售卡网点

版权所有© 渝B2-20050021-1 渝公网安备 50019002500403号 违法和不良信息举报中心

互联网出版许可证 新出网证(渝)字10号 全国400电话 - 免长途话费