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Jae-Kyu Roh

Publications and source records attributed to Jae-Kyu Roh.

At least 37 records · Page 2Linked to original sources
PubMed2005

Aphasia following striatocapsular infarction may be explained by concomitant small cortical infarct on diffusion-weighted imaging.

BACKGROUND: The underlying mechanism of aphasia following striatocapsular infarction (SCI) remains controversial. We hypothesized that aphasia resulting from SCI might be associated with concomitant cortical lesions, which can be demonstrated by diffusion-weighted imaging (DWI). METHODS: We analyzed 24 patients with left SCI who underwent DWI and MR angiography within 2 days after the onset. Aphasia was assessed by the modified Korean version of the Boston Diagnostic Aphasia Examination test. RESULTS: DWI showed the presence of additional ischemic lesions involving the cortical areas in 13 of 24 SCI patients (54%). Ten patients (42%) showed aphasia. All 10 patients with aphasia had cortical lesions in addition to SCI (p = 0.0002), whereas 21% (3/14) of the nonaphasic patients had additional cortical lesions. Conventional MRI did not reveal the presence of corresponding acute cortical lesions in any of the aphasic patients. There was no difference between the patients with and without aphasia in terms of their stroke etiology. CONCLUSIONS: Our data suggest that aphasia due to SCI in the acute stage may be attributed to direct cortical injury, whose presence can be demonstrated by DWI, even though it might be invisible on conventional imaging.

Aged↗
PubMed2005

Ipsilateral hemiparesis caused by a corona radiata infarct after a previous stroke on the opposite side.

Ipsilateral hemiparesis after a supratentorial stroke is rare. However, the role of the reorganization of the unaffected hemisphere in recovery after a stroke is poorly understood. Two patients developed ipsilateral hemiparesis after a left corona radiata infarct. Both of these patients had previously experienced contralateral hemiparesis after a right-sided supratentorial stroke. Functional magnetic resonance imaging demonstrated bilateral motor area activation during paretic left hand movement. This finding suggests that the ipsilateral hemiparesis was caused by a new stroke in the ipsilateral motor system that was functionally reorganized after the previous stroke.

Adult↗
PubMed2005

Induction method of tyrosine kinase A-mediated cell death in rat pheochromocytoma.

Nerve Growth Factor (NGF) is a neurotrophic factor that prevents apoptosis in neuronal progenitor cells. In rat pheochromocytoma (PC12) cells, tyrosine kinase A receptor (TrkA) mediates neurotrophic or protective effects, while p75 neurotrophin receptor (p75NTR) functions as a death receptor. We have determined whether TrkA mediates any cytotoxic effect. Following serum deprivation, TrkA expression increased 2.2-fold and apoptosis began with expression of Bax proapoptotic protein. Application of NGF halved cell viability but this was reversed by K252a, the TrkA inhibitor. These results confirmed the paradoxical cytotoxic effect of neurotrophic NGF via TrkA in PC12 cells following serum deprivation.

Animals↗
PubMed2005

Reversing the silencing of reporter sodium/iodide symporter transgene for stem cell tracking.

UNLABELLED: To track neural stem cells transfected with reporter gene, perpetual stem cell transgene expression is required. Referring to the knowledge about epigenetic modulation, we succeeded in reversing the silencing of sodium/sodide symporter (hNIS) transgenes transfected into human neural stem (HB1.F3) cells. METHODS: hNIS and hygromycin resistance gene were linked with IRES (Internal Ribosome Entry Site) under control of cytomegalovirus promoter, and this construct was transfected into HB1.F3 cells to yield the F3-NIS cell lines. hNIS transgene expression was examined by (125)I uptake and reverse transcriptase polymerase chain reaction (RT-PCR). The iodide uptake of F3-NIS III cells was initially higher by up to 12.9-fold than that of nontransfected HB1.F3 cells. However, repeated passage gradually silenced hNIS expression. The recovery of hNIS transgene expression by demethylating agent (5-azacytidine) or histone deacetylase inhibitor (trichostatin A; TSA) treatment was investigated. RESULTS: As hNIS transgene was gradually silenced in F3-NIS III cells, after the eighth passage its iodide uptake was 1.9-fold higher than that of nontransfected HB1.F3 cells. 5-azacytidine treatment (up to 40 micromol/L) for 24 h in F3-NIS III cells increased iodide uptake and hNIS messenger RNA (mRNA) 1.8- and 1.9-fold versus nontreated F3-NIS cells, respectively. Moreover, after TSA treatment (up to 62.5 nmol/L) for 24 h, iodide uptake and hNIS mRNA in F3-NIS III cells increased 36- and 1.9-fold versus nontreated F3-NIS III cells, respectively. The synergistic effect of demethylation and histone deacetylation inhibition was significant at high-dose 5-azacytidine and low-dose of TSA treatment. After treating F3-NIS III cells in vitro for 24 h with 62.5 nmol/L TSA, the cells were implanted into BALB/c nude mice. The TSA-treated F3-NIS III cells were clearly visible on gamma-camera imaging using (99m)Tc-pertechnetate as compared with F3-NIS III cells not treated with TSA. CONCLUSION: These results suggest that 2 well-known mechanisms of epigenetic modulation synergistically are involved in silencing reporter hNIS transgene in a neural stem cell line. Transgene silencing was reversed using demethylation and histone deacetylation inhibition. We conclude that silenced reporter transgenes once successfully expressed in stem cells might be awakened by pharmacologic treatment before infusion to track stem cells in vivo.

Animals↗
PubMed2004

Human neural stem cell transplantation reduces spontaneous recurrent seizures following pilocarpine-induced status epilepticus in adult rats.

Transplantation of neural stem cells (NSCs) can replace lost neurons and improve the functional deficits. Cell transplantation strategies have been tried in the epileptic disorder, but the effect of exogenous NSCs is unknown. In this study, we attempted to test the anti-epileptogenic effect of NSCs in adult rats with status epilepticus. Experimental status epilepticus was induced by lithium-pilocarpine injection, and beta galactosidase-encoded human NSCs were transplanted intravenously on the next day of status epilepticus. Spontaneous recurrent seizures were monitored with Racine's seizure severity scale. Immunohistochemistry with anti-beta gal, Tuj-1, NeuN, GFAP, CNPase, GluR2, parvalbumin, and GABA were performed and extracellular field excitatory postsynaptic potentials (fEPSP) were recorded. Human NSCs suppressed spontaneous recurrent seizure formation and transplanted NSCs were differentiated into GABA-immunoreactive interneurons in the damaged hippocampus. Amplitude of fEPSP in the hippocampal CA1 was reduced, which was reversed by picrotoxin. These findings suggest that NSCs could be differentiated into inhibitory interneurons and decrease neuronal excitability, which could prevent spontaneous recurrent seizure formation in adult rats with pilocarpine-induced status epilepticus.

Aggression↗
PubMed2004

Human neural stem cells improve sensorimotor deficits in the adult rat brain with experimental focal ischemia.

Ischemic stroke is caused by the interruption of cerebral blood flow that leads to brain damage with long-term sensorimotor deficits. Stem cell transplantation may recover functional deficit by replacing damaged brain. In this study, we attempted to test whether the human neural stem cells (NSCs) can improve the outcome in the rat brain with intravenous injection and also determine the migration, differentiation and the long-term viabilities of human NSCs in the rat brain. Focal cerebral ischemia was induced by intraluminal thread occlusion of middle cerebral artery (MCA). One day after surgery, the rats were randomly divided into two groups: NSCs-ischemia vs. Ischemia-only. Human NSCs infected with retroviral vector encoding beta galactosidase were intravenously injected in NSCs-ischemia group (5 x 10(6) cells) and the same amount of saline was injected in Ischemia-only group for control. The animals were evaluated for 4 weeks using turning in an alley (TIA) test, modified limb placing test (MLPT) and rotarod test. Transplanted cells were detected by X gal cytohistochemistry or beta gal immunohistochemistry with double labeling of other cell markers. The NSCs-ischemia group showed better performance on TIA test at 2 weeks, and MLPT and rotarod test from 3 weeks after ischemia compared with the Ischemia-only group. Human NSCs were detected in the lesion side and labeled with marker for neurons or astrocytes. Postischemic hemispheric atrophy was noted but reduced in NSCs-ischemia group. X gal+ cells were detected in the rat brain as long as 540 days after transplantation. Our data suggest intravenously transplanted human NSCs can migrate and differentiate in the rat brain with focal ischemia and improve functional recovery.

Animals↗
PubMed2004

HMG-CoA reductase inhibitor, atorvastatin, promotes sensorimotor recovery, suppressing acute inflammatory reaction after experimental intracerebral hemorrhage.

BACKGROUND AND PURPOSE: Statins have neuroprotective effects on ischemic stroke. They modify the endothelial function, increase blood flow, and inhibit thrombus formation, which are independent of lipid-lowering effects. However, whether statins have a protective effect toward hemorrhagic stroke is yet unknown. To test this possibility, we attempted to determine the effect of atorvastatin on experimental intracerebral hemorrhage (ICH). METHODS: ICH was induced using stereotaxic infusion of collagenase into the left basal ganglia in adult rats. Atorvastatin (1 mg/kg or 10 mg/kg) or phosphate-buffered saline was administered for 2 weeks. To monitor the sensorimotor deficits, limb placing and Rotorod tests were performed. Hematoma volume, brain water content, and hemispheric atrophy were analyzed. Immunohistochemical staining for myeloperoxidase (MPO), microglia (OX42), inducible nitric oxide synthase (iNOS), or endothelial nitric oxide synthase (eNOS) was performed. Perihematomal cell death was determined by TUNEL staining. RESULTS: The atorvastatin-treated ICH group showed better performance on Rotorod and limb placing tests when compared with the vehicle-treated group (P<0.01). The hematoma volumes between groups were not different, but the brain water content and hemispheric atrophy were reduced in the atorvastatin-treated ICH group. Atorvastatin reduced TUNEL-positive cells, iNOS expression, and MPO-positive or OX42-positive cells in the perihematomal regions in a dose-dependent manner, whereas it increased eNOS expression. CONCLUSIONS: The present study shows that atorvastatin reduces the perihematomal cell death via antiinflammation, which is associated with sensorimotor recovery after experimental ICH.

Animals↗
PubMed2004

VEGF protects human cerebral hybrid neurons from in vitro ischemia.

Vascular endothelial growth factor (VEGF), the most potent angiogenic peptide, protects the neurons against experimental ischemia. However, its neuroprotective effect on human brain is unknown. The present study attempted to determine whether VEGF can protect human cerebral neurons in vitro. A1 human hybrid clonal neurons (human cerebral neuron + neuroblastoma cell) were exposed to hypoxia with glucose deprivation. Pretreatment with VEGF reduced the A1 cell death, and VEGFR-2/Flk-1 and VEGF increased with a neuroprotective effect. However, the human neuroblastoma or neuroglioma cells failed to show these findings. Our results suggest that VEGF can protect human cerebral neurons from cell death after an ischemic insult in vitro, which is correlated to both increased expression of VEGFR-2/Flk-1 and VEGF within the cells.

Cell Count↗
PubMed2004

Diffusion-weighted MRI and 99mTc-HMPAO SPECT in delayed relapsing type of carbon monoxide poisoning: evidence of delayed cytotoxic edema.

BACKGROUND: Carbon monoxide (CO) is a common cause of poisoning, and its sequelae include a progressive (25%) and a delayed relapsing form (75%). We report the diffusion-weighted MRI (DWI) findings in the delayed relapsing form of CO poisoning and characterize the types of edema. METHODS: From November 1, 2000 to June 1, 2003, 5 consecutive patients (2 men, 3 women, range of age: 54-67 years), who had the delayed relapsing type of CO poisoning, underwent DWI, conventional MRI, MR angiography and SPECT. CO poisoning was diagnosed by the presence of a typical clinical history, an abnormally increased level of serum carboxyhemoglobin and MRI findings. Apparent diffusion coefficient (ADC) values were measured in all of the abnormal lesions with visual inspection of DWI and T(2)-weighted echo-planar imaging. RESULTS: DWI showed high signal intensities in bilateral periventricular white matter, in the splenium of the corpus callosum, in internal capsules, and brainstem showing moderately decreased ADC values. In the globus pallidus, the ADC values were rather increased with low signal intensities on DWI. Brain SPECT showed decreased perfusion in bilateral white matter and some parts of the cerebral cortex, which correlated well with the DWI findings. CONCLUSIONS: We suggest that prominent, symmetric restricted diffusion can occur in periventricular white matter, brainstem, and corpus callosum after the delayed relapsing type of CO poisoning. Delayed cytotoxic edema can occur in this setting, which provides a new guidance for the pathogenesis of CO poisoning and the differential diagnosis of white matter diseases.

Aged↗
PubMed2004

Clinical and radiologic differences between primary intracerebral hemorrhage with and without microbleeds on gradient-echo magnetic resonance images.

BACKGROUND: Microbleeds on gradient-echo magnetic resonance (MR) imaging reflect bleeding-prone microangiopathy. The microbleeds are frequently detected in patients with primary intracerebral hemorrhage (PICH). However, some patients do not have microbleeds. OBJECTIVE: To clarify the risk factors associated with microbleeds in PICH, thus providing insight into the pathogenesis of PICH. DESIGN: Prospective study. SETTING: Neurology department of a tertiary referral center. Patients A consecutive series of 107 patients with PICH. INTERVENTIONS: Gradient-echo MR imaging to determine distribution patterns and numbers of microbleeds. MAIN OUTCOME MEASURES: Clinical variables and the associated MR imaging abnormalities in patients with PICH with and without microbleeds. RESULTS: Patients with PICH who had microbleeds were significantly older (65.9 +/- 10.9 years) than those without microbleeds (53.9 +/- 13.0 years; P<.001), and previous stroke, medication with antithrombotics or anticoagulants, lacunes, and leukoaraiosis were more common in patients with microbleeds. However, potential triggering events tending to raise the blood pressure were more common in cases of PICH without microbleeds (18 [56.3%] vs 10 [15.4%]). In logistic regression analysis, age (odds ratio and 95% confidence interval: 1.07, 1.01-1.14), advanced leukoaraiosis (7.79, 1.05-57.74), number of lacunes (1.66, 1.21-2.28), and potential triggering events (0.18, 0.04-0.90) were independent risk factors associated with the presence of microbleeds in patients with PICH. CONCLUSIONS: Primary intracerebral hemorrhage without microbleeds was more common in younger patients with precipitating events, whereas PICH with microbleeds was more common in elderly patients with prominent ischemic change and frequent use of antithrombotics or anticoagulants. Our findings might help to determine the pathogenetic type for secondary prevention.

Adolescent↗
PubMed2004

Musical training-induced functional reorganization of the adult brain: functional magnetic resonance imaging and transcranial magnetic stimulation study on amateur string players.

We used the combined technique of functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) to observe changes that occur in adult brains after the practice of stringed musical instruments. We carried out fMRI on eight volunteers (aged 20-22 years): five novices and three individuals who had discontinued practice for more than 5 years. The motor paradigm contained a repetitive lift-abduction/fall-adduction movement of the left/right little finger, carried out with maximum efforts without pacing. The sensory paradigm was to stimulate the same little finger using a string. In parallel to the fMRI acquisition, TMS motor maps for the little finger were obtained using a frameless stereotactic neuronavigation system. After the baseline study, each participant began to learn a stringed instrument. Newly developed fMRI activations for the left little finger were observed 6 months after practice at multiple brain regions including inferior parietal lobule, premotor area (PMA), left precuneus, right anterior superior temporal gyrus, and posterior middle temporal gyrus. In contrast, new activations were rarely observed for the right little finger. The TMS study revealed new motor representation sites for the left little finger in the PMA or supplementary motor area (SMA). Unexpectedly, TMS motor maps for the right little finger were reduced significantly. Among new fMRI activations for sensory stimuli of the left little finger, the cluster of highest activation was located in the SMA. Collectively, these data provide insight into orchestrated reorganization of the sensorimotor and temporal association cortices contributing to the skillful fingering and musical processing after the practice of playing stringed instruments.

Adult↗
PubMed2004

Cerebral microbleeds in patients with hypertensive stroke. Topographical distribution in the supratentorial area.

OBJECTIVE: To analyse the topography of cerebral microbleeds (CMBs) visualized by T2*-weighted gradient-echo MR imaging in the supratentorial brain area, based on the anatomical classification of the regions and the arterial territories. BACKGROUND: CMBs are associated with hypertension and the risk of intracerebral hemorrhage; however, little is known about the cerebral topography of CMBs. METHODS: We examined 164 consecutive patients with hypertensive stroke who underwent T2*-weighted gradient-echo MRI. The anatomical locations and the vascular territories of the CMBs were determined in the subcortical white matter, basal ganglia/internal capsule and thalamus along the standard axial slices. RESULTS: We detected 2,193 CMBs in 98 patients (13.4+/-39.0 per patient). The CMBs showed a significant predilection for the temporo-occipital area of the subcortical white matter, the posterolateral part of the upper putamen, and the lateral nuclei of the mid-level thalamus. The most common arterial territories were those of the middle-posterior cerebral artery in the white matter, the middle cerebral artery in the basal ganglia, and the thalamogeniculate artery in the thalamus. CONCLUSIONS: These findings were quite similar to the cerebral topography of intracerebral hemorrhage described in the literature. Our results suggest that CMBs are regionally associated with intracerebral hemorrhage.

Adult↗
PubMed2004

Celecoxib induces functional recovery after intracerebral hemorrhage with reduction of brain edema and perihematomal cell death.

The selective cyclooxygenase-2 (COX-2) inhibitor has been reported to have antiinflammatory, neuroprotective, and antioxidant effects in ischemia models. In this study, the authors examined whether a selective COX-2 inhibitor (celecoxib) reduces cerebral inflammation and edema after intracerebral hemorrhage (ICH), and whether functional recovery is sustained with longer treatment. ICH was induced using collagenase in adult rats. Celecoxib (10 or 20 mg/kg) was administered intraperitoneally 20 minutes, 6 hours, and 24 hours after ICH and then daily thereafter. Seventy-two hours after ICH induction, the rats were killed for histologic assessment and measurement of brain edema and prostaglandin E2. Behavioral tests were performed before and 1, 7, 14, 21, and 28 days after ICH. The brain water content of celecoxib-treated rats decreased both in lesioned and nonlesioned hemispheres in a dose-dependent manner. Compared with the ICH-only group, the number of TUNEL-positive, myeloperoxidase-positive, or OX42-positive cells was decreased in the periphery of hematoma and brain prostaglandin E2 level was reduced in the celecoxib-treated group. Celecoxib-treated rats recovered better by the behavioral tests at 7 days after ICH throughout the 28-day period, and the earlier the drug was administered, the better the functional recovery. Evidence of similar effects in an autologous blood-injected model showed that direct collagenase toxicity was not the major cause of inflammation or cell death. These data suggest that celecoxib treatment after ICH reduces prostaglandin E2 production, brain edema, inflammation, and perihematomal cell death in the perihematomal zone and induces better functional recovery.

Animals↗
PubMed2004

Continuous cytosine-b-D-arabinofuranoside infusion reduces ectopic granule cells in adult rat hippocampus with attenuation of spontaneous recurrent seizures following pilocarpine-induced status epilepticus.

Brief or prolonged seizures induce various patterns of plasticity. Axonal or dendritic remodelling and development of ectopic granule cells have been described in the hilus and molecular layer of the adult rodent hippocampus. Hippocampal cell proliferation also occurs after seizures. However, whether the seizure-induced cell proliferation plays a pathological or reparative role in the epileptic brain is unknown. In this study, we attempted to suppress the seizure-induced cell proliferation with the antimitotic agent cytosine-b-D-arabinofuranoside (Ara-C) and to examine the development of spontaneous recurrent seizures (SRS). Experimental status epilepticus was induced with pilocarpine, and Ara-C or vehicle alone was infused continuously with an osmotic minipump. SRS were video-monitored. BrdU immunohistochemistry was used for the spatial and temporal analysis of hippocampal cell proliferation, and double labelling with NeuN, calbindin and GFAP antibodies was performed for the differentiation of BrdU-positive cells. Timm staining was also performed for evaluation of mossy fibre sprouting (MFS). With continuous Ara-C infusion, the likelihood of developing SRS was decreased and, during the latent period, the development of ectopic granule cells in the hilus and new glia in the CA1 area was reduced when compared with the vehicle-infused group, while MFS was not altered. The results suggest that the hippocampal cell proliferation plays a pro-epileptogenic role rather than a compensatory role, and that the epileptogenic process may be associated with the generation of new glia in the CA1 area and/or new neurons in the dentate gyrus, particularly the ectopically located hilar granule cells.

Animals↗
PubMed2004

Diagnosis of moyamoya disease with transcranial Doppler sonography: correlation study with magnetic resonance angiography.

BACKGROUND AND PURPOSE: Although the diagnosis of moyamoya disease may be confirmed by digital subtraction angiography, recent studies have shown the accuracy of magnetic resonance angiography. Characteristics of transcranial Doppler, a noninvasive and cost-effective method, and specific transcranial Doppler parameters reflecting distinct vascular status in moyamoya disease are explored. METHOD AND PATIENTS: Consecutive patients (> 15 years of age) diagnosed with moyamoya disease by a typical clinical history and digital sub traction angiography or magnetic resonance angiography were included. The statuses of the anterior, middle, and posterior cerebral arteries were graded as stage 1, stage 2, and stage 3 by magnetic resonance angiography. Mean flow velocity and pulsatility index were compared between these groups, and the receiver operating characteristic analysis was used to define transcranial Doppler criteria for distinct vascular status. RESULTS: Forty-five patients were included (37 women; mean age, 34.9 +/- 11.4 years). Mean flow velocity was higher and pulsatility index was lower in stage 2 (P < .01), while mean flow velocity was lower and pulsatility index was higher in stage 3 than in stage 1 (P < .01). Cutoff values reflecting stenosis or occlusion with substantial sensitivity and specificity were as follows: mean flow velocity > 85 cm/s or pulsatility index < 0.60 for stage 2, and mean flow velocity < 50 cm/s for stage 3 of middle cerebral artery; mean flow velocity > 80 cm/s or pulsatility index < 0.60 for stage 2 of anterior cerebral artery; and mean flow velocity > 60 cm/s or pulsatility index < 0.60 for stage 2 of posterior cerebral artery. CONCLUSION: Transcranial Doppler may help to refine magnetic resonance angiography findings and thus help clinicians differentiate severity or stages of moyamoya disease.

Adolescent↗
PubMed2004

Topographical distribution of pontocerebellar microbleeds.

BACKGROUND AND PURPOSE: Microbleeds (MBs) visualized by use of T2*-weighted gradient-echo MR imaging are pathologic blood-breakdown products after tiny cerebral hemorrhages. The topographic distribution of the lesions has not been compared with that of symptomatic intracerebral hemorrhage (ICH). The purpose of this study was to evaluate the distribution of MBs in the pontocerebellar region and to compare it with the distribution of ICHs reported in the literature. METHODS: We examined 164 consecutive hypertensive patients with ischemic infarction or spontaneous ICH over a 1-year period. Two experienced neuroradiologists assessed cerebral localization of MBs without prior knowledge of the clinical information and in consensus. After obtaining 16 standard axial brain images, we analyzed the anatomic locations and the vascular territories of the MBs in the pontocerebellar area. RESULTS: We detected 374 pontocerebellar MBs in 40 patients (8.1 +/- 12.7). Pontine MBs showed a significant predilection for the central portion (middle part along the axial plane, 3.4 +/- 4.9 [P < .01]; medial part along the coronal plane, 3.4 +/- 4.1 [P < .01]) and mostly belonged to the territory of the anteromedial group arising from the basilar artery. Cerebellar MBs had a frequent distribution around the dentate nucleus, occurring significantly more in the lower half, in the medial part (3.4 +/- 4.6; P < .01), and in the middle part along the axial plane (4.8 +/- 7.0; P < .01). CONCLUSION: These findings were similar to the topography of ICH described in the literature. Our results suggest that MBs may be a lesional marker for ICH.

Aged↗