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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Overall, stroke is a common disease that can have devastating results. Treatment of stoke has been, for the most part, supportive in nature. Recently, more aggressive intervention has been used, particularly thrombolysis. Although such intervention can have devastating consequences, it has shown some promise, particularly in the arena of intraarterial administration. Although much work is needed to find the ideal agents and methods of administration, screening of patients may hold the key to success and the limitations of complications. Determination of exactly which patients will benefit and which will not and which will have complications and which will not, remains for the most part an enigma. Only through further investigation in a controlled, collaborative manner can such information be obtained.
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PMID:Radiologic intervention in the acute stroke patient. 889 25

The southeastern region of the United States has been recognized for 6 decades as an area of excess cerebrovascular mortality rates. While the reasons for the disease variation remain an enigma, South Carolina has consistently been the forerunner of the "Stroke Belt." To determine the effects of nativity (birthplace) on stroke mortality rates in South Carolina, proportional mortality ratios (PMRs) were calculated for stroke deaths in South Carolina during 1980-1996 according to birthplace and stratified by gender, race, age, and educational status. The analyses revealed a graded risk of stroke by birthplace, with the highest PMRs (95% CI) among individuals born in South Carolina (104.8 [103.4 to 106.3]), intermediate PMRs in those born in the Southeast other than South Carolina (92.5 [90.2 to 94.9]), and lowest PMRs for those born outside the Southeast (77.4 [74.9 to 80.1]). The lower stroke PMRs for individuals born outside the Southeast were more striking in blacks (51.8 [45.2 to 59.3]) than in whites (84.9 [82.0 to 88.0]) and for men (73.3 [69.5 to 77.3]) than women (83.5 [79.9 to 87.3]). The findings, particularly in blacks, were not explainable by gender, differences in age, and/or markers of educational and socioeconomic status. These findings suggest that nativity is a significant risk marker for the geographic variation in stroke mortality. Moreover, the regional disparities for nativity and subsequent stroke mortality appear to be greater in blacks than in whites and for men than for women. An understanding of factors linking birthplace to risk for cerebrovascular mortality could facilitate efforts directed at stroke prevention.
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PMID:Impact of nativity and race on "Stroke Belt" mortality. 1040 24

The pathophysiology of developmental or acquired stuttering still remains an enigma. In a few cases, the developmental stuttering that had disappeared spontaneously or as a result of therapy reoccurred following a brain lesion. We report on a patient with return of developmental stuttering following a left hemispheric stroke. This case supports the theory that acquired brain lesions may cause a return of stuttering, possibly by interfering with the compensatory mechanism(s) that once had relieved the developmental stuttering.
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PMID:Return of stuttering after stroke. 1087 40

There is a wealth of experimental and clinical information showing that hypertension, hyperglycaemia, hyperthermia and intracranial hypertension are each independent indicators of a poor prognosis after stroke, but there is an astonishing lack of evidence from randomised controlled trials to tell us how to manage these problems, bearing in mind their frequency in stroke patients. The therapeutic options will, in most cases, not involve patented drugs, and financial support for running the necessary randomised controlled trials will have to come from government or charity sponsors rather than from the pharmaceutical industry. It is vital that academic researchers now devise studies of appropriate design and size to answer these important questions. In the absence of randomised data, severe hyperglycaemia and pyrexia should be treated, whilst acute hypertension is probably best left untreated unless very severe or complicated by other medical conditions. The management of cerebral oedema remains an enigma.
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PMID:Optimising homeostasis. 1109 91

High blood pressure is common in the western world and is a major risk factor for the development of stroke. Lowering blood pressure reduces the risk of first and recurrent stroke. High blood pressure is also common in acute stroke and is independently associated with a poor prognosis, in part due to promoting early recurrence and the development of fatal cerebral oedema in patients with ischaemic stroke and, possibly, re-bleeding in those with haemorrhagic stroke. However, the management of blood pressure remains an enigma--its lowering could improve outcome by reducing recurrence or worsen outcome by reducing regional perfusion in the face of dysfunctional cerebral autoregulation. Conversely, raising blood pressure might improve outcome by raising regional perfusion or worsen it by inducing cerebral oedema and early recurrence. Administration of some vaso-active drugs (beta-receptor antagonists and calcium channel blockers) can worsen outcome and reduce cerebral blood flow. In contrast, other drug classes--angiotensin- converting enzyme inhibitors, angiotensin receptor antagonists and nitrates--appear to lower blood pressure without reducing measures of cerebral perfusion. In the absence of definitive trial data, which is urgently needed, blood pressure should not be routinely lowered unless it is extreme (systolic blood pressure >220 mm Hg) or associated with arterial dissection or cardiac ischaemia or failure, in which case cautious lowering (<15%), perhaps with an angiotensin-converting enzyme inhibitor, angiotensin receptor antagonist or nitrate, is appropriate.
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PMID:High blood pressure as risk factor and prognostic predictor in acute ischaemic stroke: when and how to treat it? 1469 80

The induction of hypometabolism in cells and organs to reduce ischemia damage holds enormous clinical promise in diverse fields, including treatment of stroke and heart attack. However, the thought that humans can undergo a severe hypometabolic state analogous to hibernation borders on science fiction. Some mammals can enter a severe hypothermic state during hibernation in which metabolic activity is extremely low, and yet full viability is restored when the animal arouses from such a state. To date, the underlying mechanism for hibernation or similar behaviors remains an enigma. The beneficial effect of hypothermia, which reduces cellular metabolic demands, has many well-established clinical applications. However, severe hypothermia induced by clinical drugs is extremely difficult and is associated with dramatically increased rates of cardiac arrest for nonhibernators. The recent discovery of a biomolecule, 5'-AMP, which allows nonhibernating mammals to rapidly and safely enter severe hypothermia could remove this impediment and enable the wide adoption of hypothermia as a routine clinical tool.
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PMID:Is human hibernation possible? 1818 3

There is an increasing interest in nootropic drugs for the treatment of CNS disorders. Since the last meta-analysis of the clinical efficacy of piracetam, more information has accumulated. The primary objective of this systematic survey is to evaluate the clinical outcomes as well as the scientific literature relating to the pharmacology, pharmacokinetics/pharmacodynamics, mechanism of action, dosing, toxicology and adverse effects of marketed and investigational drugs. The major focus of the literature search was on articles demonstrating evidence-based clinical investigations during the past 10 years for the following therapeutic categories of CNS disorders: (i) cognition/memory; (ii) epilepsy and seizure; (iii) neurodegenerative diseases; (iv) stroke/ischaemia; and (v) stress and anxiety. In this article, piracetam-like compounds are divided into three subgroups based on their chemical structures, known efficacy and intended clinical uses. Subgroup 1 drugs include piracetam, oxiracetam, aniracetam, pramiracetam and phenylpiracetam, which have been used in humans and some of which are available as dietary supplements. Of these, oxiracetam and aniracetam are no longer in clinical use. Pramiracetam reportedly improved cognitive deficits associated with traumatic brain injuries. Although piracetam exhibited no long-term benefits for the treatment of mild cognitive impairments, recent studies demonstrated its neuroprotective effect when used during coronary bypass surgery. It was also effective in the treatment of cognitive disorders of cerebrovascular and traumatic origins; however, its overall effect on lowering depression and anxiety was higher than improving memory. As add-on therapy, it appears to benefit individuals with myoclonus epilepsy and tardive dyskinesia. Phenylpiracetam is more potent than piracetam and is used for a wider range of indications. In combination with a vasodilator drug, piracetam appeared to have an additive beneficial effect on various cognitive disabilities. Subgroup 2 drugs include levetiracetam, seletracetam and brivaracetam, which demonstrate antiepileptic activity, although their cognitive effects are unclear. Subgroup 3 includes piracetam derivatives with unknown clinical efficacies, and of these nefiracetam failed to improve cognition in post-stroke patients and rolipram is currently in clinical trials as an antidepressant. The remaining compounds of this subgroup are at various preclinical stages of research. The modes of action of piracetam and most of its derivatives remain an enigma. Differential effects on subtypes of glutamate receptors, but not the GABAergic actions, have been implicated. Piracetam seems to activate calcium influx into neuronal cells; however, this function is questionable in the light of findings that a persistent calcium inflow may have deleterious impact on neuronal cells. Although subgroup 2 compounds act via binding to another neuronal receptor (synaptic vesicle 2A), some of the subgroup 3 compounds, such as nefiracetam, are similar to those of subgroup 1. Based on calculations of the efficacy rates, our assessments indicate notable improvements in clinical outcomes with some of these agents.
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PMID:Piracetam and piracetam-like drugs: from basic science to novel clinical applications to CNS disorders. 2016 67

The authors attempt to solve the enigma about the possible aphasia of the Byzantine Emperor Manuel II Palaeologus (1391-1425) in the 3-year period between his first and his second and fatal stroke. The texts of historians and chroniclers reveal that Manuel remained semi-paralyzed at bed and his motor disability alienated him from the state affairs and condemned him to isolation from all embassies and contact with others, except his family. Only the funeral oration of the Bishop Bessarion raises the suspicion of a speechless emperor. All testimonies referring to this infirmity are examined.
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PMID:The three last years of Manuel II Palaeologus' reign between two stroke attacks: aphasia or not? 2200 57

Molecular motors such as myosins are allosteric enzymes that power essential motility functions in the cell. Structural biology is an important tool for deciphering how these motors work. Myosins produce force upon the actin-driven conformational changes controlling the sequential release of the hydrolysis products of ATP (Pi followed by ADP). These conformational changes are amplified by a 'lever arm', which includes the region of the motor known as the converter and the adjacent elongated light chain binding region. Analysis of four structural states of the motor provides a detailed understanding of the rearrangements and pathways of communication in the motor that are necessary for detachment from the actin track and repriming of the motor. However, the important part of the cycle in which force is produced remains enigmatic and awaits new high-resolution structures. The value of a structural approach is particularly evident from clues provided by the structural states of the reverse myosin VI motor. Crystallographic structures have revealed that rearrangements within the converter subdomain occur, which explains why this myosin can produce a large stroke in the opposite direction to all other myosins, despite a very short lever arm. By providing a detailed understanding of the motor rearrangements, structural biology will continue to reveal essential information and help solve current enigma, such as how actin promotes force production, how motors are tuned for specific cellular roles or how motor/cargo interactions regulate the function of myosin in the cell.
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PMID:How myosin motors power cellular functions: an exciting journey from structure to function: based on a lecture delivered at the 34th FEBS Congress in Prague, Czech Republic, July 2009. 2217 85

Brain oscillations reflect pattern formation of cell assemblies' activity, which is often disturbed in neurological and psychiatric diseases like depression, schizophrenia and stroke. In the neurobiological analysis and treatment of these conditions, transcranial electric currents applied to the brain proved beneficial. However, the direct effects of these currents on brain oscillations have remained an enigma because of the inability to record them simultaneously. Here we report a novel strategy that resolves this problem. We describe accurate reconstructed localization of dipolar sources and changes of brain oscillatory activity associated with motor actions in primary cortical brain regions undergoing transcranial electric stimulation. This new method allows for the first time direct measurement of the effects of non-invasive electrical brain stimulation on brain oscillatory activity and behavior.
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PMID:In vivo assessment of human brain oscillations during application of transcranial electric currents. 2378 80


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