Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cerebral microcirculation has a series of complex relationships with arterial hypertension determined, on one hand, by the size and the location of the vessels involved, and on the other hand, by the chronic or acute nature of the hypertension. The small arterial vessels of the cerebral parenchyma react to the effects of chronic hypertension with irreversible structural changes, whose pathologic and radiological correlation is chronic ischemia of the white substance, shown by paleness of the white substance, together with small lacunar infarctions, with a clinical association of dementia, motor disorders and pseudo-bulbar syndrome. With the appearance of an acute rise in arterial pressure, these vessels react with generally reversible changes which lead to an increase in the permeability of the hematoencephalic barrier with formation of cerebral edema and a clinical association generally demonstrating the focal nature of the vascular abnormality (such as in hypertensive encephalopathy with changes in posterior hemispheric predominance) or its unilateral location in cases in which the process occurs in one of the carotid territories (post-endarterectomy).
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PMID:[Hypertensive vascular disease and cerebral microcirculation]. 1037 57

EGb 761 is a standardized extract of dried leaves of Ginkgo biloba containing 24% ginkgo-flavonol glycosides, 6% terpene lactones such as ginkgolides A, B, C, J and bilobalide. Its broad spectrum of pharmacological activities allows it to be in adequacy to the numerous pathological requirements--hemodynamic, hemorheological, metabolic--which occur in cerebral, retinal, cochleovestibular, cardiac or peripheral ischemia. Moreover, EGb 761 has direct effects against necrosis and apoptosis of neurons and improves neural plasticity as evidenced in vestibular compensation. At the molecular and the cellular levels, some evidence obtained with animal models indicates that EGb 761 can interact as a free radical-scavenger and a inhibitor of lipid peroxidation with all, or nearly all reactive oxygen species; maintains ATP content by a protection of mitochondrial respiration and preservation of oxidative phosphorylations; exerts arterial and venous vasoregulator effects involving the release of endothelial factors and the catecholaminergic system. Moreover, EGb 761 regulates ionic balance in damaged cells and exerts a specific and potent Platelet-activating factor antagonist activity. Numerous well-controlled clinical studies, realized in Europe and in USA, have revealed that EGb 761 is an effective therapy for a wide variety of disturbances of cerebral function, ranging from cerebral impairment of ischemic vascular origins (i.e. multi infarct dementia), early cognitive decline to mild-to-moderate cases of the more severe types of senile dementias (including Alzheimer's disease) or mixed origins (i.e. psychoorganic origin). Improvement of signs and symptoms have been demonstrated for cognitive functions, particularly for memory loss, attention, alertness, vigilance, arousal and mental fluidity. Some clinical studies have showed that EGb 761 treatment may improve the capacity of geriatric patients to cope with the stressful demands of daily life. The explanation is a dual stress-alleviating action of EGb 761: its facilitates behavioral adaptation to stress and may decrease the excess of cortisol release to stress. Moreover, EGb 761 shows a specific neuroprotective effects to hippocampic cells. Regarding the visual system, experimental studies have shown that EGb 761 can inhibit or reduce the functional retinal impairments resulting from ischemia-reperfusion, photo-degeneration, diabetic or proliferative retinopathy. Clinical studies have revealed that EGb 761 may be useful in treating visual activity impairments and damages to the visual field associated with chronic cerebrovascular insufficiency, senile macular degeneration and diabete mellitus. Regarding the vestibular and auditory systems, experimental and clinical studies have shown the efficacy of EGb 761 in treating hypoacusis, tinnitus, vertigo, dizziness and other symptoms of vestibulocochlear disorders. At least, adequatly controlled studies in patients with peripheral arterial occlusive disease have provided good evidence for therapeutic efficacy in intermittent claudication. The future of EGb 761 is undoubtedly in the promise in slowing the progression of Alzheimer's disease. Indeed, two recent american clinical studies have shown the efficacy and safety of EGb 761 in patients with mild to severe Alzheimer's disease and multi-infarct dementia. In clinical terms, progression of symptoms was delayed by approximately 6 months. Actually new clinical studies are undertaken in USA and Europe. At the dawn of the third millenium (the Sixth for Ginkgo biloba) we propose a state of art about it.
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PMID:[Ginkgo biloba extract (EGb 761). State of knowledge in the dawn of the year 2000]. 1048 50

Paget's disease of bone is associated with involvement of the central and peripheral nervous system. The brain, spinal cord, cauda equina, spinal roots, and cranial nerves can be affected in Paget's disease due to their anatomic relationship to bone. Neurologic syndromes are uncommon but include headache, dementia, brain stem and cerebellar dysfunction, cranial neuropathies, myelopathy, cauda equina syndrome, and radiculopathies. The central complications result from pagetic involvement of the skull. Expansion of diseased bone can result in compression of cranial nerves as they exit their bony foramina. Softening of the skull leads to basilar invagination with compression of the brain stem, cerebellum, and lower cranial nerves. Brain stem compression can cause hydrocephalus. Rarely, there is direct compression of the brain from acute epidural hematoma or hypertrophy of the calvarium. Myelopathy, cauda equina syndrome, and radiculopathies most commonly result from hypertrophy of the spine with direct compression. Spinal stenosis can also result from ossification of extradural structures or pathologic fractures. Ischemia from vascular compression or a steal syndrome has also been described. Neurologic complications rarely occur due to sarcomatous transformation of pagetic bone. Magnetic resonance imaging (MRI), computerized tomography (CT)-myelography, and bone X-rays are helpful to localize the lesion and direct therapy. Treatment options include surgical decompression, ventricular shunt placement, and medical management with calcitonin and/or the bisphosphonates. The selection of treatment will vary depending upon the rate of progression and the severity of the neurologic deficit.
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PMID:The neurologic complications of Paget's disease. 1051 Feb 21

Acetyl-L-carnitine (ALC) is an ester of the trimethylated amino acid, L-carnitine, and is synthesized in the human brain, liver, and kidney by the enzyme ALC-transferase. Acetyl-L-carnitine facilitates the uptake of acetyl CoA into the mitochondria during fatty acid oxidation, enhances acetylcholine production, and stimulates protein and membrane phospholipid synthesis. ALC, similar in structure to acetylcholine, also exerts a cholinomimetic effect. Studies have shown that ALC may be of benefit in treating Alzheimer's dementia, depression in the elderly, HIV infection, diabetic neuropathies, ischemia and reperfusion of the brain, and cognitive impairment of alcoholism.
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PMID:Acetyl-L-carnitine. 1060 18

Problems with diagnostic criteria for vascular dementia (VaD) stem from the inadequacy of the current dementia concept, a paradigm based on amnestic and other cortical deficits typical of Alzheimer disease (AD). However, most cases of VaD are due to subcortical lesions such as Binswanger-type periventricular white matter ischemia, or strokes causing decreased frontal activation and diaschisis-mediated cerebral hypoperfusion. We propose a new definition of dementia based on executive dysfunction and a formal assessment of executive control functions (ECF) for the diagnosis of VaD. The instruments proposed are the rapid screening executive clock-drawing task (CLOX; Royall et al. J Neurol Neurosurg Psychiatry 1998;64:588-94), and the more comprehensive Executive Interview Test (EXIT25; Royall et al. J Am Geriatr Soc 1992;40:122-6). Extensive application of these tests in elderly subjects in retirement communities has shown that both are brief, simple to administer, and more sensitive case-finding tools for cognitively impaired individuals than the Mini-Mental State Examination (MMSE). These three tests (CLOX, EXIT25, MMSE) accurately separate nondemented subjects from those with cortical or subcortical (frontal system) dementias. In addition, for controlled clinical trials of VaD, formal evaluation of motor and frontal sphincter functions--usually not considered part of the dementia syndrome--should also be included. Evaluation of gait and falls, timed-walk, manual dexterity, timed finger-tapping, and frontal bladder control (urge incontinence and nocturia) should improve determination of functional status and disability, and more accurately measure the effects of potential therapies.
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PMID:Executive control function: a rational basis for the diagnosis of vascular dementia. 1060 85

The neuroprotective glial cell modulator propentofylline has been used in clinical trials involving more than 800 patients with vascular dementia (VaD). These data derive from two sources: a pooled group of VaD patients from four early phase III European trials, and a multinational European/Canadian phase III study (MN 305) that features a combined randomized withdrawal/delayed onset of progression design to evaluate the effect of propentofylline on disease progression. In the pooled studies, DSM-III-R criteria, Hachinski Ischemia Scores, computed tomography (CT), and magnetic resonance imaging (MRI) were used to select subjects with mild-to-moderate disease; in MN 305, National Institute of Neurological Disorders and Stroke/Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN) criteria and neurologic examinations (including CT and MRI scans) were used to select patients with possible or probable VaD. The use of a central rater to assess cerebrovascular disease in neuroradiologic examinations for study MN 305 was considered to be a key feature for reducing the heterogeneity of the VaD patient population. In addition, the inclusion of patients with possible VaD in this trial greatly increased the number of eligible patients; subgroup analyses revealed no substantial differences between patients with probable versus possible VaD, justifying their inclusion in the study. VaD patients exhibited a more pronounced placebo response in global assessments compared with the Alzheimer disease population in a parallel study. In addition, they experienced less deterioration over time with respect to cognitive and global assessments. Beneficial effects of propentofylline were consistently demonstrated in the domains of cognitive and global function for both VaD populations; however, no treatment benefits could be demonstrated for activities of daily living, possibly due to factors relating to the study population/design, the lack of a validated test instrument for such patients, the caregiver-related phenomenon of "tutoring," or the nature of the disease itself.
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PMID:Clinical trials of propentofylline in vascular dementia. European/Canadian Propentofylline Study Group. 1060 97

Memantine is a moderate-affinity, voltage-dependent, uncompetitive antagonist of N-methyl-D-aspartate (NMDA) receptors. In contrast to competitive NMDA antagonists, Memantine is well tolerated in humans and is being developed for the treatment of dementia. The pathogenesis of vascular dementia (VaD) is largely unknown, and is likely multifactorial, but it involves the impairment of blood circulation as a common denominator. There is broad evidence for the efficacy of Memantine in several animal models of ischemia. Memantine also acts on several secondary, potentially contributing factors in VaD such as neuronal depolarization, removal of magnesium block of NMDA receptors, chronic overstimulation of these receptors, and, possibly, mitochondrial dysfunction. Among others, it also has additional positive effects on long-term potentiation and cognition in standard animal models of impaired synaptic plasticity. Recently, clinical efficacy of Memantine has been shown in an etiologically mixed population of severely demented patients, including those with VaD. Given the difficulties of diagnosing VaD in clinical practice, an optimal antidementive drug should be beneficial in both Alzheimer disease and VaD. Preclinical data presented in this paper indicate that such benefits can be achieved with Memantine. In addition, phase II clinical data in dementia are summarized, and two ongoing pivotal trials in VaD are described. Suggestions for VaD guideline development are made regarding clinical instruments, and etiologies and severity stages are considered.
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PMID:Pharmacologic rationale for memantine in chronic cerebral hypoperfusion, especially vascular dementia. 1060 98

Silent stroke is one of the risk factors of dementia. In the present study, we used a novel focal ischemic animal model to investigate the effects of comparatively small changes of cerebral blood flow (CBF) on the expression of beta-amyloid precursor protein (APP) mRNA. Focal ischemia was achieved by introducing a 4-0 monofilament to the bifurcation of anterior and middle cerebral arteries. Brain samples were harvested from ischemic core and penumbra of cortices at 1, 4 and 7 days following ischemia. The expression of APP mRNA was assessed by RT-PCR. The CBF was decreased to 50% for 1 day after stroke and recovered to 90% at the fourth day after stroke. The changes of CBF were accompanied by an increase in the expression of APP mRNA. APP mRNA increased to 208% and 152% in the penumbra and core ischemic regions, respectively, on the fourth day after MCAO and remained high through the seventh day of ischemia. This study suggests brain hypoperfusion enhances APP mRNA expression and may contribute to the progression of cognitive impairment after silent stroke.
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PMID:Hypoperfusion induces overexpression of beta-amyloid precursor protein mRNA in a focal ischemic rodent model. 1062 1

The effects of (-)-huperzine A, a promising therapeutic agent for Alzheimer's disease, on learning behavior and on alterations of the cholinergic system, the oxygen free radicals and energy metabolites induced by permanent bilateral ligation of the common carotid arteries were investigated in rats. Daily oral administration of huperzine A produced a significant improvement of the deficit in the learning of the water maze task, beginning 28 days after ischemia, correlating to about 33-40% inhibition of acetylcholinesterase activity in cortex and hippocampus. Huperzine A significantly restored the decrease in choline acetyltransferase activity in hippocampus and significantly reduced the increases in superoxide dismutase, lipid peroxide, lactate and glucose to their normal levels. The present findings demonstrate that the improvement by huperzine A of the cognitive dysfunction in the late phase in chronically hypoperfused rats is due to its effects, not only on the cholinergic system, but also on the oxygen free radical system and energy metabolism. Our results strongly suggest that huperzine A has therapeutic potential for the treatment of dementia caused by cholinergic dysfunction and/or decrease of cerebral blood flow.
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PMID:Huperzine A improves cognitive deficits caused by chronic cerebral hypoperfusion in rats. 1085 49

Recent epidemiological studies have shown that vascular risk factors may be involved in Alzheimer's disease (AD) as well as dementia in general. To investigate the relation between a vascular disorder and AD pathology, current criteria are defective because most depend on exclusion of a cerebrovascular disorder. Epidemiological studies have indicated the possibilities that arteriosclerosis, abnormal blood pressure, diabetes mellitus and smoking may be related to the pathogenesis of AD. As for the mechanism that vascular disorders influence AD, it is presumed that amyloid deposition may be caused by a vascular disorder. Alternatively, a vascular event may cause progression of subclinical AD to a clinical stage. Insulin resistance and apolipoprotein E may also be involved in these mechanisms. Our studies show that ischemia-induced the Alzheimer-associated gene presenilin 1 (PS1) and endoplasmic reticulum-stress, generated from a vascular disorder, may unmask clinical AD symptoms caused by presenilin mutation, suggesting that a vascular factor might be involved in the onset of familial AD.
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PMID:Are cerebrovascular factors involved in Alzheimer's disease? 1086 6


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