187 research outputs found
Controller Area Network With Flexible Data Rate (CAN FD) Eye Diagram Prediction
A method for predicting the eye diagram for a controller area network with a flexible data rate (CAN FD) is proposed in this article. A CAN FD changes a data rate according to the status to overcome the limitation of latency. In other words, when data to be transmitted are accumulated, the CAN FD increases the data rate up to 5 Mb/s. The CAN FD has a bus topology consisting of multiple electronic control units, which results in a significant amount of signal reflection. Thus, the above causes the signal integrity analysis uncertain. To avoid this, this article proposes a simplified model for the CAN FD and the eye diagram prediction method based on it. The proposed method has the deterministic and statistical: the deterministic part uses an iterative single bit response method for bit probabilities of a CAN FD packet, and the statistical part uses a modified double edge response method for the flexible data rate. For verification, this article compares the predicted eye diagram to the measured eye diagram, and they are nearly the same when the CAN FD operates at the nominal data rate of 1 and optional data rate of 2 Mb/s
Cerebral Venous Thrombosis and Livedo Reticularis in a Case with MTHFR 677TT Homozygote
Hyperhomocysteinemia associated with methylene terahydrofolate reductase (MTHFR) mutation can be a risk factor for idiopathic cerebral venous thrombosis. We describe the first case of MTHFR 677TT homozygote with cerebral venous thrombosis and livedo reticularis. A 45-year-old man presented with seizures and mottled-like skin lesions, that were aggravated by cold temperature. Hemorrhagic infarct in the right frontoparietal area with superior sagittal sinus thrombosis was observed. He had hyperhomocysteinemia, low plasma folate level, and MTHFR 677TT homozygote genotype, which might be associated with livedo reticularis and increase the risk for cerebral venous thrombosis
A Korean Case of Juvenile Muscular Atrophy of Distal Upper Extremity (Hirayama Disease) with Dynamic Cervical Cord Compression
We present a Korean case of Hirayama disease with its typical neuroradiological findings of forward displacement of cervical dural sac and compression of the lower cervical cord during neck flexion. A 15-yr-old boy was presented with a one-year history of progressive weakness and atrophy affecting bilateral hands and forearms. The electrodiagnostic findings were compatible with the lesion of the anterior horn cells at the C7, C8, and T1 spinal segments. With neck flexion, cervical magnetic resonance imaging (MRI) showed the anterior shifting of the lower cervical dural sac resulting in the cord compression of those segments. Presumably, this disease might have been prevalent in Korea frequently under the diagnosis of "benign focal amyotrophy". In this regard, we discuss the clinical importance of cervical MRI with neck flexion and anticipate the increasing reports of the case substantiated by its characteristic radiological features
Downregulated miR-18b-5p triggers apoptosis by inhibition of calcium signaling and neuronal cell differentiation in transgenic SOD1 (G93A) mice and SOD1 (G17S and G86S) ALS patients
Abstract
Background
MicroRNAs (miRNAs) are endogenous non-coding RNAs that regulate gene expression at the post-transcriptional level and are key modulators in neurodegenerative diseases. Overexpressed miRNAs play an important role in ALS; however, the pathogenic mechanisms of deregulated miRNAs are still unclear.
Methods
We aimed to assess the dysfunction of RNAs or miRNAs in fALS (SOD1 mutations). We compared the RNA-seq of subcellular fractions in NSC-34 WT (hSOD1) and MT (hSOD1 (G93A)) cells to find altered RNAs or miRNAs. We identified that Hif1ฮฑ and Mef2c were upregulated, and Mctp1 and Rarb were downregulated in the cytoplasm of NSC-34 MT cells.
Results
SOD1 mutations decreased the level of miR-18b-5p. Induced Hif1ฮฑ which is the target for miR-18b increased Mef2c expression as a transcription factor. Mef2c upregulated miR-206 as a transcription factor. Inhibition of Mctp1 and Rarb which are targets of miR-206 induces intracellular Ca2+ levels and reduces cell differentiation, respectively. We confirmed that miR-18b-5p pathway was also observed in G93A Tg, fALS (G86S) patient, and iPSC-derived motor neurons from fALS (G17S) patient.
Conclusions
Our data indicate that SOD1 mutation decreases miR-18b-5p, which sequentially regulates Hif1ฮฑ, Mef2c, miR-206, Mctp1 and Rarb in fALS-linked SOD1 mutation. These results provide new insights into the downregulation of miR-18b-5p dependent pathogenic mechanisms of ALS
Current Issues in Migraine Genetics
Migraine often runs in families and is associated with both genetic and environmental factors. Clinical and genetic heterogeneity as well as the influence of environmental factors have hampered the identification of the gene responsible for migraine disorder. Family/twin studies suggest the presence of hereditary susceptibility. Several different types of mutations or association studies with genetic polymorphism in neurotransmitters, inflammatory cytokines, homocysteine metabolism, mitochondria, or other risk genes in cerebrovascular disorders have been reported. Recently, progress of molecular genetics in familial hemiplegic migraine has provided important insights, a channelopathy, and now extending to a growing list of membrane excitability disorders. Further identification of candidate genes for migraine and exploring the correlation between phenotype and genotype are expected in the future for the understanding of migraine pathophysiology
Early intravenous infusion of sodium nitrite protects brain against in vivo ischemia-reperfusion injury
BACKGROUND AND PURPOSE: The rate of nitric oxide (NO) generation from nitrite is linearly dependent on reductions in oxygen and pH levels. Recently, nitrite-derived NO has been reported to exert a profound protection against liver and heart ischemia-reperfusion injury. In this study, we hypothesized that nitrite would be reduced to NO in the ischemic brain and exert NO-dependent neuroprotective effects. METHODS: Cerebral ischemia-reperfusion injury was induced by intraluminal thread occlusion of middle cerebral artery in the adult male rats. Solutions of sodium nitrite were infused intravenously at the time of reperfusion. Sodium nitrate and carboxy-PTIO (30 minutes before ischemic surgery), a direct NO scavenger, were infused for comparisons. RESULTS: Nitrite reduced infarction volume and enhanced local cerebral blood flow and functional recovery. The effects were observed at concentrations of 48 nmol and 480 nmol, but not at 4800 nmol nitrite and 480 nmol nitrate. The neuroprotective effects of nitrite were inhibited completely by the carboxy-PTIO. The 480 nmol nitrite attenuated dihydroethidium activity, 3-nitrotyrosine formation, and lipid peroxidation in the ischemic brain. CONCLUSIONS: Nitrite exerted profound neuroprotective effects with antioxidant properties in the ischemic brains. These results suggest that nitrite, as a biological storage reserve of NO, may be a novel therapeutic agent in the setting of acute stroke.This study was supported by a Korean Research Foundation grant
funded by the Korean Government (MOEHRD, Basic Research
Promotion Fund, KRF-2005-015-E00182)
Circulating endothelial progenitor cells as a new marker of endothelial dysfunction or repair in acute stroke
BACKGROUND AND PURPOSE: Understanding on distinct subsets of endothelial progenitor cells may provide insights of endothelial dysfunction or repair in the acute ischemic event. Recent in vitro data have reported the colony-forming unit (CFU) and outgrowth cell population as a subset of endothelial progenitor cells. In this study, we undertook to validate the significance of CFU number and outgrowth cell yield in acute stroke. METHODS: Mononuclear cells were isolated from the peripheral blood of 75 patients with acute stroke, 45 patients with chronic stroke, and 40 age-matched healthy volunteers. CFU numbers were counted after culturing them for 7 days, and outgrowth cell appearance was measured during the 2 months of culture. Endothelial progenitor cell function was also evaluated by matrigel plate assays. Independent parameters predicting CFU number and outgrowth cell yield were assessed using logistic regression analysis. RESULTS: The CFU numbers and tube formation abilities in matrigel assays were significantly reduced in patients with acute stroke compared with patients with chronic stroke or healthy control subjects. Moreover, patients with large artery atherosclerosis had much lower CFU numbers and functional activities than ones with cardioembolism. Outgrowth cells were isolated from 10% of healthy control subjects and 22% of patients with chronic stroke during the cultures, but from 71% of patients with stroke. Multivariate analysis identified glycosylated hemoglobin and National Institutes of Health Stroke Scale on admission as significant independent predictors of a low CFU number and a high isolation frequency of outgrowth cells, respectively. CONCLUSIONS: CFU number may thus represent an accumulated endothelial progenitor cell dysfunctional status, whereas outgrowth cell appearance may reflect the resilience of the systemic circulation to acute ischemic stress
Direct Generation of Neurosphere-Like Cells from Human Dermal Fibroblasts
Neural stem cell (NSC) transplantation replaces damaged brain cells and provides disease-modifying effects in many neurological disorders. However, there has been no efficient way to obtain autologous NSCs in patients. Given that ectopic factors can reprogram somatic cells to be pluripotent, we attempted to generate human NSC-like cells by reprograming human fibroblasts. Fibroblasts were transfected with NSC line-derived cellular extracts and grown in neurosphere culture conditions. The cells were then analyzed for NSC characteristics, including neurosphere formation, gene expression patterns, and ability to differentiate. The obtained induced neurosphere-like cells (iNS), which formed daughter neurospheres after serial passaging, expressed neural stem cell markers, and had demethylated SOX2 regulatory regions, all characteristics of human NSCs. The iNS had gene expression patterns that were a combination of the patterns of NSCs and fibroblasts, but they could be differentiated to express neuroglial markers and neuronal sodium channels. These results show for the first time that iNS can be directly generated from human fibroblasts. Further studies on their application in neurological diseases are warranted
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