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

Degeneration and death of neurons is the fundamental process responsible for the clinical manifestations of many different neurological disorders of aging, incuding Alzheimer's disease, Parkinson's disease and stroke. The death of neurons in such disorders involves apoptotic biochemical cascades involving upstream effectors (Par-4, p53 and pro-apoptotic Bcl-2 family members), mitochondrial alterations and caspase activation. Both genetic and environmental factors, and the aging process itself, contribute to intiation of such neuronal apoptosis. For example, mutations in the amyloid precursor protein and presenilin genes can cause Alzheimer's disease, while head injury is a risk factor for both Alzheimer's and Parkinson's diseases. At the cellular level, neuronal apoptosis in neurodegenerative disorders may be triggered by oxidative stress, metabolic compromise and disruption of calcium homeostasis. Neuroprotective (antiapoptotic) signaling pathways involving neurotrophic factors, cytokines and "conditioning responses" can counteract the effects of aging and genetic predisposition in experimental models of neurodegenerative disorders. A better understanding of the molecular underpinnings of neuronal death is leading directly to novel preventative and therapeutic approaches to neurodegenerative disorders.
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PMID:Neurodegenerative disorders and ischemic brain diseases. 1132 Oct 43

Cerebral amyloid beta-protein angiopathy (CAA) is a key pathological feature of patients with Alzheimer's disease and certain related disorders. In these conditions the CAA is characterized by the deposition of Abeta within the cerebral vessel wall and, in severe cases, hemorrhagic stroke. Several mutations have been identified within the Abeta region of the Abeta protein precursor (AbetaPP) gene that appear to enhance the severity of CAA. We recently described a new mutation within the Abeta region (D23N) of AbetaPP that is associated with severe CAA in an Iowa kindred (Grabowski, T. J., Cho, H. S., Vonsattel, J. P. G., Rebeck, G. W., and Greenberg, S. M. (2001) Ann. Neurol. 49, 697-705). In the present study, we investigated the effect of this new D23N mutation on the processing of AbetaPP and the pathogenic properties of Abeta. Neither the D23N Iowa mutation nor the E22Q Dutch mutation affected the amyloidogenic processing of AbetaPP expressed in H4 cells. The A21G Flemish mutation, in contrast, resulted in a 2.3-fold increase in secreted Abeta peptide. We also tested synthetic wild-type and mutant Abeta40 peptides for fibrillogenesis and toxicity toward cultured human cerebrovascular smooth muscle (HCSM) cells. The E22Q Dutch, D23N Iowa, and E22Q,D23N Dutch/Iowa double mutant Abeta40 peptides rapidly assembled in solution to form fibrils, whereas wild-type and A21G Flemish Abeta40 peptides exhibited little fibril formation. Similarly, the E22Q Dutch and D23N Iowa Abeta40 peptides were found to induce robust pathologic responses in cultured HCSM cells, including elevated levels of cell-associated AbetaPP, proteolytic breakdown of smooth muscle cell alpha-actin, and cell death. Double mutant E22Q,D23N Dutch/Iowa Abeta40 was more potent than either single mutant form of Abeta in causing pathologic responses in HCSM cells. These data suggest that the different CAA mutations in AbetaPP may exert their pathogenic effects through different mechanisms. Whereas the A21G Flemish mutation appears to enhance Abeta production, the E22Q Dutch and D23N Iowa mutations enhance fibrillogenesis and the pathogenicity of Abeta toward HCSM cells.
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PMID:Pathogenic effects of D23N Iowa mutant amyloid beta -protein. 1144 Oct 13

Bed rest is an integral part of treatment of numerous diseases. Typical examples are bone fractures of lower extremities and pelvis. Temporary immobilization is necessary also, e.g., in heart diseases (stroke), backbone and imminent abortion. The sick organism spares energy during the bed rest wich is beneficial. However, bed rest results in many alterations which are disadavantageous. They concern the function of almost all organs and systems but affect most significantly the locomotor and ciruclatory systems. Bed rest brings also about changes in the composition of peripheral blood and functions of the morphotic elements of blood. Red blood cells are subjected to the action of large amounts of reactive oxygen species (ROS). During oxidation of hemoglobin to methemoglobin superoxide radical anion (O2-) is formed: HbFe2+ + O2 --> MetHbFe3+ + O2- (1) Ferrous and ferric ions present in the cytoplasm of red blood cells may be catalysts of the Fenton reaction leading to the production of the hydroxyl radical: O2- + Fe3+ --> O2- + Fe2+ (2) Fe2+ + H2O2 --> Fe3+ + OH + HO- (3) OH shows a tremendous reactivity. It may react with lipids, proteins, nucleic acids and carbohydrates. The process of lipid peroxidation is best understood. It concerns mainly polyunsaturated fatty acids present in cell membranes. Peroxidation of membrane lipids decreases membrane fluidity and impairs its barrier function. The lowered membrane fluidity compromises erythrocyte deormability which in turn disturbs oxygen delivery to the tissues. End productions of lipid peroxidation are low-molecular wieght compounds, among them carbohydrates (ethane and pentane) and aldehydes, e.g. malondialdehyde (MDA). MDA concentration is an acknowldeged marker of the intensity of lipid peroxidation. Erythrocytes contain a complex system of protection against the action of ROS. It includes various enzymatic and non-enzymatic mechanism. The most important antioxidative enzymes of the red blood cells are superoxide dismutase (Cu,Zn-SOD, EC 1.15.1.1) catalase (CAT, EC 1.11.1.6) and glutathione peroxidase (GSH-Px, EC 1.11.1.9). Cu,Zn-SOD catalyzes the dismuation of O2- to hydrogen peroxide (H2O2). Catalase and peroxidase remove H2O2 and, moreover, GSH-Px can reduce lipid peroxides. Under normal conditions an equilibrium exists between the formation and removal ROS. If ROS are formed in excess or the defensive antioxidative mechanism are inefficient, oxidative stress develops. Derangement of the equilibrium between the formation and removal of ROS is important in the pathosgenesis of many diseases, e.g. atherosclerosis, diabetes, Down syndrome and Alzheimer disease. There are literature data on disturbances of enzymatic antioxidant defense mechanism of blood plateless during bed rest. This study was aimed at an examination of the post-traumatic bed rest on the enzymatic antioxidative defense mechanisms and lipid peroxidation in erythrocytes.
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PMID:Effect of long term bed rest in men on enzymatic antioxidative defence and lipid peroxidation in erythrocytes. 1154 39

The heme oxygenase (HO) and nitric oxide (NO) synthase (NOS) systems display notable similarities as well as differences. HO and NOS are both oxidative enzymes using NADPH as an electron donor. The constitutive forms of the enzyme are differentially activated, with calcium entry stimulating NOS by binding to calmodulin, whereas calcium entry activates protein kinase C to phosphorylate and activate HO2. Although both NO and carbon monoxide (CO) stimulate soluble guanylyl cyclase to form cGMP, NO also S-nitrosylates selected protein targets. Both involve constitutive and inducible biosynthetic enzymes. However, functions of the inducible forms are virtual opposites. Macrophage-inducible NOS generates NO to kill other cells, whereas HO1 generates bilirubin to exert antioxidant cytoprotective effects and also provides cytoprotection by facilitating iron extrusion from cells. The neuronal form of HO, HO2, is also cytoprotective. Normally, neural NO in the brain seems to exert some sort of behavioral inhibition. However, excess release of NO in response to glutamate's N-methyl-d-aspartate receptor activation leads to stroke damage. On the other hand, massive neuronal firing during a stroke presumably activates HO2, leading to neuroprotective actions of bilirubin. Loss of this neuroprotection after HO inhibition by mutant forms of amyloid precursor protein may mediate neurotoxicity in Familial Alzheimer's Disease. NO and CO both appear to be neurotransmitters in the brain and peripheral autonomic nervous system. They also are physiologic endothelial-derived relaxing factors for blood vessels. In the gastrointestinal pathway, NO and CO appear to function as coneurotransmitters, both stimulating soluble guanylyl cyclase to cause smooth muscle relaxation.
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PMID:Neural roles for heme oxygenase: contrasts to nitric oxide synthase. 1157 59

Cerebral amyloid angiopathy (CAA) is one of the two most common cerebral arteriopathies seen in the brains of elderly patients. The other is arteriosclerosis (AS), historically considered a consequence of chronic hypertension and also described as lipohyalinosis (LH), a clinicopathologic association that is increasingly questioned. These and other less frequently encountered degeneralions of the cerebral microvasculature (CADASIL, Binswanger subcortical leukoencephalopathy) share the common feature of degeneration of the medial smooth muscle layer within arteriolar walls. This can be dramatic in CAA, in the course of which complete replacement of medial smooth muscle by fibrillar amyloid may occur. It is a less prominent feature of CADASIL and BSLE: in the latter condition, medial smooth muscle hyperplasia, possibly a response to some kind of injury, is a more dramatic finding. In some of these "angiomyopathies", fibrinoid necrosis of the arterial wall and microaneurvsm formation may lead to stroke, manifest as cerebral hemorrhage. With CADASIL and BSLE, ischemic brain injury is more common. In the case of CAA, upregulation of the Abeta-amyloid precursor protein occurs when arteriolar smooth muscle cells in culture are exposed to prolonged hypoxia, especially with reoxygenation. Injury to arteriolar smooth muscle cells may be one mechanism by which angiomyopathies progress and become symptomatic.
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PMID:Non-CAA angiopathies and their possible interactions with cerebral amyloid angiopathy. 1167 85

Cerebral amyloid angiopathy (CAA) due to the accumulation of amyloid beta-protein (Abeta) occurs in up to half of elderly individuals and in most cases of Alzheimer's disease (AD). Following identification of the apolipoprotein E (APOE) epsilon4 allele as a risk factor for AD, APOE epsilon4 was also found to be associated with asymptomatic CAA. The major clinical manifestation of CAA is stroke due to a lobar hemorrhage. A complex relationship between APOE epsilon4, APOE epsilon2 and hemorrhage associated with CAA (CAAH) is emerging. Pathological studies have demonstrated that APOE epsilon2 is over-represented among patients with CAAH. This remains the case for patients with co-existing Alzheimer's disease, who otherwise have a very low epsilon2 allele frequency. Other forms of intracranial hemorrhage do not share the same association, indicating that APOE epsilon2 has a specific association with CAAH. Patients with the epsilon2 allele and CAAH are more likely to have taken anticoagulant or antiplatelet medication, had hypertension or had minor head trauma than non-epsilon2 carriers. In addition, the epsilon2 allele is specifically associated with CAA-associated microangiopathic changes such as fibrinoid necrosis and concentric splitting of the vessel wall.
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PMID:APOE gene polymorphism as a risk factor for cerebral amyloid angiopathy-related hemorrhage. 1167 91

The dense-cored plaques are considered the pathogenic type of amyloid deposition in Alzheimer's disease brains because of their predominant association with dystrophic neurites. Nevertheless, in > 90% of cases of Alzheimer's disease amyloid is also deposited in cerebral blood vessel walls (congophilic amyloid angiopathy; CAA) but its role in Alzheimer's disease pathogenesis remains enigmatic. Here, we report a family (family GB) in which early-onset Alzheimer's disease was caused by a novel presenilin 1 mutation (L282V). This was unusually severe CAA reminiscent of the Flemish amyloid precursor protein (A692G) mutation we reported previously, which causes Alzheimer's disease and/or cerebral haemorrhages. In family GB, however, the disease presented as typical progressive Alzheimer's disease in the absence of strokes or stroke-like episodes. Similarly, neuroimaging studies and neuropathological examination favoured a degenerative over a vascular dementia. Interestingly, an immunohistochemical study revealed that, similar to causing dense-cored amyloid plaques, CAA also appeared capable of instigating a strong local dystrophic and inflammatory reaction. This was suggested by the observed neuronal loss, the presence of tau- and ubiquitin-positive neurites, micro- and astrogliosis, and complement activation. Together, these data suggest that, like the dense-cored neuritic plaques, CAA might represent a pathogenic lesion that contributes significantly to the progressive neurodegeneration that occurs in Alzheimer's disease.
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PMID:Cerebral amyloid angiopathy is a pathogenic lesion in Alzheimer's disease due to a novel presenilin 1 mutation. 1170 93

Cerebral amyloid angiopathy (CAA), defined by deposition of the beta-amyloid peptide in medium and small cortical and meningeal vessels, is a well-recognized cause of hemorrhagic stroke. This paper reviews the accumulating evidence supporting an additional role for CAA in producing vessel dysfunction, reduced cerebral blood flow and ischemia. Ischemic lesions are characteristic of several hereditary CAA syndromes, including a recently described mutation of the amyloid precursor protein associated with dementia (but not hemorrhagic stroke) in an Iowa family. Ischemic lesions are seen in some sporadic CAA patients as well, and recent data from transgenic mice suggest potential mechanisms by which beta-amyloid may alter vessel physiology. Future studies will seek to define the clinical importance of vascular beta-amyloid as a potential target for drug therapy in dementia.
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PMID:Cerebral amyloid angiopathy and vessel dysfunction. 1190 Dec 42

Born in Poland in 1931, Henryk Miroslaw Wisniewski, obtained MD at the Medical School in Gdansk (1955), where he continued his neuropathological research awarded with Ph. D. in 1960. During 1961-1962 a worked as a Visiting Scientist at NIH (Institute of Neurology and Communicative Diseases and Stroke). In Medical School in Warsaw he was promoted to Docent degree (an associate professor). In 1966 he emigrated with his family to New York, where he was a Research Associate and Professor at Albert Einstein College of Medicine (1966-1975) Subsequently he became a Director of the State Institute for Basic Research in Developmental Disabilities Staten Island. In New York he remained till his early death at the age of 68. Prof. Wisniewski advanced pathological research concerning the development of dementia, including Alzheimer disease. His investigations proved that presentile dementia (Alzheimer disease) is almost identical with senile dementia. That is why he is called the pioneer of modern Alzheimers research. The comments about his scientific contribution were generously published in scientific journals and daily press. The New York Times cited Dr Mony de Leon Prof. of Psychiatry statement reflecting so well Prof. Wisniewski's achievements "He taught us what the lesions for Alzheimers looked like, what they were made of and how they worked".
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PMID:[Outstanding contribution of prof. Henryk M. Wisniewski (1931-1999) to the world neuropathology in 20th century]. 1192 63

Tauhe main component of cerebral amyloid angiopathy (CAA) in Alzheimer's disease is the amyloid-beta protein (Abeta), a 4-kDa polypeptide derived from the beta-amyloid protein precursor (APP). The accumulation of Abeta in the basement membrane has been implicated in the degeneration of adjacent vascular smooth muscle cells (VSMC). However, the mechanism of Abeta toxicity is still unclear. In this study, we examined the effect of substrate-bound Abeta on VSMC in culture. The use of substrate-bound proteins in cell culture mimics presentation of the proteins to cells as if bound to the basement membrane. Substrate-bound Abeta peptides were found to be toxic to the cells and to increase the rate of cell death. This toxicity was dependent on the length of time the peptide was allowed to 'age', a process by which Abeta is induced to aggregate over several hours to days. Oxidative stress via hydrogen peroxide (H2O2) release was not involved in the toxic effect, as no decrease in toxicity was observed in the presence of catalase. However, substrate-bound Abeta significantly reduced cell adhesion compared to cells grown on plastic alone, indicating that cell-substrate adhesion may be important in maintaining cell viability. Abeta also caused an increase in the number of apoptotic cells. This increase in apoptosis was accompanied by activation of caspase-3. Homocysteine, a known risk factor for cerebrovascular disease, increased Abeta-induced toxicity and caspase-3 activation in a dose-dependent manner. These studies suggest that Abeta may activate apoptotic pathways to cause loss of VSMC in CAA by inhibiting cell-substrate interactions. Our studies also suggest that homocysteine, a known risk factor for other cardiovascular diseases, could also be a risk factor for hemorrhagic stroke associated with CAA.
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PMID:Toxicity of substrate-bound amyloid peptides on vascular smooth muscle cells is enhanced by homocysteine. 1207 66


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