Brain and nerve = Shinkei kenkyū no shinpo
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Antiplatelet therapy is indicated in patients with non-cardioembolic stroke. The clinically used antiplatelet agents for secondary stroke prevention in this group of patients include the cyclooxygenase-1 (COX-1) inhibitor aspirin, the ADP receptor (P2Y12) inhibitors clopidogrel and ticlopidine, and the phosphodiesterase (PDE) inhibitors cilostazol and dipyridamole. Per medical economic data, aspirin is the most widely used antiplatelet agent. ⋯ The CHANCE study conducted in China showed a lower incidence of ischemic stroke in DAPT-treated patients than in those treated with aspirin monotherapy, while the incidence of hemorrhagic stroke was similar between the 2 treatment groups. However, DAPT should be restricted in the acute phase of stroke or TIA in acute settings. Novel antiplatelet agents have been developed for stroke prevention, and large randomized clinical trials should be conducted to evaluate the efficacy and safety of these agents when used singularly or in combination.
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With the demographic shift in life expectancy inexorably increasing in developed countries, dementia is set to become one of the most important health problems worldwide. In recent years, cerebral small vessel disease (SVD) has received much attention as an important cause of dementia. The reason for this is twofold: firstly, arteriosclerosis (type 1 SVD) is the leading cause of vascular cognitive impairment, and secondly, cerebral amyloid angiopathy (CAA; type 2 SVD) is an almost invariable accompaniment of Alzheimer's disease. ⋯ As arteries stiffen with age or with other co-morbid factors such as life-related diseases, amyloid β (Aβ) synthesis becomes upregulated, resulting in the deposition of insoluble Aβ not only in the parenchyma as senile plaques but also in the perivascular drainage pathways as CAA. Therefore, therapeutic strategies such as vasoactive drugs that enhance the patency of this Aβ drainage pathway may facilitate Aβ removal and help prevent cognitive decline in the elderly. Based on this emerging paradigm, clinical trials are warranted to investigate whether a neurovascular therapeutic approach can effectively halt cognitive decline and act as a preemptive medicine for patients at risk of dementia.
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"Blindsight" is a phenomenon whereby hemianopic patients with damage in the primary visual cortex (V1) are able to process visual information in their blind visual field. Two pathways that bypass the V1 may be responsible for this residual vision. The first pathway is the retinotectal pathway in which the superior colliculus in the midbrain receives direct retinal signals and sends them to the extrastriate cortex via the pulvinar. ⋯ I emphasize three points: 1) crosstalk exists between the retinotectal pathway and the geniculo-extrastriate pathway, that is, the projection from the superficial layer of the superior colliculus to the koniocellular layer of the lateral geniculate nucleus; 2) three visual channels (the luminance in the magnocellular pathway, the red-green opponency in the parvocellular pathway, and the blue-yellow opponency in the koniocellular pathway) are not independent, as previously assumed; and 3) a global reorganization in the brain circuit occurs following the lesions of the V1 and subsequent recovery. Finally, I introduce a recent study that employed a saliency computational model to quantitatively evaluate the residual visual channels in blindsight monkeys during free-viewing behavior. Their findings suggest that plastic changes occur in the color-processing pathways.
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Central nervous system hyperexcitability disorders, known as stiff-man/person syndrome (SPS), are thought to be related to the regulatory disturbance of inhibitory synaptic transmission of motor neurons in the brainstem and spinal cord. SPS is characterized by stiffness and spasms of the axis and limbs and is divided into two clinical subgroups: classic SPS, which affects the lumbar, trunk, and proximal limb muscles, and SPS-plus syndrome. The latter comprises (1) the stiff-limb subtype, in which symptom is limited to the lower limbs; (2) jerking stiff-man syndrome, characterized by chronically progressive stiffness and myoclonus; and (3) acute-onset and progressive encephalomyelitis with rigidity and myoclonus. ⋯ In paraneoplastic SPS, anti-amphiphysin antibodies have been shown in patients with breast cancer or small cell lung cancer. One case of mediastinal tumor with anti-gephyrin antibodies has also been reported. However, the roles of these autoantibodies in the pathomechanisms of SPS have not yet been elucidated.
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Alzheimer's disease (AD) is the most common type of dementia in the elderly and has multiple causes. The amyloid precursor protein (APP), presenilin1 (PSEN1), and presenilin2 (PSEN2) genes were identified as causative genes in a small number of families with autosomal dominant early-onset forms of AD (ADEOAD). However, many AD cases are sporadic and the late-onset type, which develops after 65 years of age. ⋯ Mutations in the causative genes of ADEOAD have been also observed in both familial LOAD and sporadic EOAD. Furthermore, new causative genes have been identifies in some families by whole genome or exome analyses. Considering the new common disease-rare variants hypothesis, personal genome sequence analysis is a potential strategy for identifying AD risk or protective genes.