Biomedical subjects

B I Lee

Publications and source records attributed to B I Lee.

At least 19 recordsLinked to original sources

PubMed2006

Association of aortic plaque with intracranial atherosclerosis in patients with stroke.

OBJECTIVE: To determine whether there is a relationship between aortic plaques and intracranial (IC) atherosclerosis. METHODS: We reviewed 922 patients with stroke who had both transesophageal echocardiography and cerebral angiography. The plaques of these patients were classified as either complex aortic plaques (CAP), which protruded > or =4 mm or were present as mobile lesions in the proximal aorta, or simple aortic plaques (SAP), which were <4 mm or present in the descending aorta. Cerebral artery atherosclerosis was classified as either an IC or extracranial (EC) atherosclerosis. RESULTS: Among the 922 patients, we found aortic plaques in 237 patients (26%). There were 111 (47%) patients of SAP, 74 (31%) patients with CAP, and 52 (22%) patients that had both SAP and CAP. Angiography showed IC or EC atherosclerosis in 511 patients (55%). The presence of aortic plaques was significantly associated with IC or EC atherosclerosis. The significance appeared to be due to the strong association between the presence of SAP and IC atherosclerosis (51% SAP vs 35% no plaques; odds ratio = 1.94, 95% CI: 1.17 to 3.21). In the multiple logistic regression analysis, SAP were independent predictors of IC atherosclerosis CONCLUSIONS: The presence of simple aortic plaques may be a marker of advanced vascular disease. Detection of simple aortic plaques during transesophageal echocardiography may have clinical implications because patients with these plaques frequently had concomitant intracranial atherosclerosis, a risk factor for stroke.

Aged↗

PubMed2006

Physical phantom of typical Korean male for radiation protection purpose.

Dose distribution within a human body can be measured using physical anthropomorphic phantoms. In an effort to establish reference Korean physical model, the first Korean physical phantom of average Korean adult male was constructed using computed tomography (CT) images of a healthy volunteer. The body dimension of the subject was close to that of average Korean male. The source images were obtained using fusion positron emission tomography machine at Radiation Health Research Institute in Korea, and ported into rapid prototyping process. The physical phantom was composed of three tissue-equivalent materials: epoxy resin, urethane foam and polyurethane representing bone, lungs and soft tissues, respectively. The densities of the tissue-equivalent materials were close to those recommended by the International Commission on Radiation Units and measurements. To facilitate dose mapping, the phantom was sliced into 2 cm sections. Hole grids for thermoluminescence (TL) dosemeter chips were drilled. To verify the appropriateness of the physical phantom, organ doses of selected organs were measured for reference photon beam, and compared with those computed by tomographic model constructed from the same CT images. Absorbed doses converted from TL relative response showed good agreement within 7% with those calculated.

Body Burden↗

PubMed2003

The TB structural genomics consortium: a resource for Mycobacterium tuberculosis biology.

The TB Structural Genomics Consortium is an organization devoted to encouraging, coordinating, and facilitating the determination and analysis of structures of proteins from Mycobacterium tuberculosis. The Consortium members hope to work together with other M. tuberculosis researchers to identify M. tuberculosis proteins for which structural information could provide important biological information, to analyze and interpret structures of M. tuberculosis proteins, and to work collaboratively to test ideas about M. tuberculosis protein function that are suggested by structure or related to structural information. This review describes the TB Structural Genomics Consortium and some of the proteins for which the Consortium is in the progress of determining three-dimensional structures.

Amino Acid Sequence↗

PubMed2003

Thyrotoxic autoimmune encephalopathy: a repeat positron emission tomography study.

Thyroid related autoantibodies have been related to the development of encephalopathy, known as Hashimoto's encephalopathy. However, their relation with the encephalopathy occurring in patients with Graves' disease has not been well established. The case is reported of a 51 year old woman presenting with subacute progressive dementia with evidence of hyperthyroidism. She had Graves' disease associated with high titres of thyroid related autoantibodies. Her encephalopathy was not improved by antithyroid drugs, but promptly responded to corticosteroid treatment, and stabilised with a gradual reduction of thyroid related autoantibody titres. Brain positron emission tomography initially showed a diffuse and multifocal cerebral hypometabolism with subsequent normalisation on her clinical recovery, which was consistent with the acute and reversible cerebral inflammation probably mediated by autoimmune mechanisms.

Autoantibodies↗

PubMed2001

Bcl-2 blocks cisplatin-induced apoptosis by suppression of ERK-mediated p53 accumulation in B104 cells.

Bcl-2 has been reported to inhibit neurotoxicity induced by cisplatin. However, neither the mechanism of cisplatin-induced neurotoxicity nor the mechanism by which Bcl-2 confers neuroprotection is clear. In this study, the signaling pathways involved in cisplatin-induced neurotoxicity were examined using a rat neuroblastoma cell line, B104. Treatment of B104 cells with cisplatin induced apoptosis, accompanying the accumulation of p53 and Bax protein. Interestingly, extracellular signal-regulated kinase 1/2 (ERK1/2) activities of MAP kinases were markedly enhanced prior to cisplatin-induced accumulation of p53 and Bax. Inhibition of ERK1/2 activities using PD98059, a selective MEK inhibitor, blocked the apoptotic cell death preventing cisplatin-induced accumulation of p53 and Bax. These results suggest that ERK mediates cisplatin-induced p53 activation to trigger apoptosis in B104 cells. Overexpression of Bcl-2 in B104 cells resulted in the complete resistance to cisplatin-induced apoptosis blocking ERK activation and the subsequent signaling pathway of p53. Our study clearly demonstrates that the action site of Bcl-2 localizes upstream of ERK in cisplatin-induced apoptotic signaling pathway.

Animals↗

PubMed2001

Crystallization and preliminary X-ray crystallographic analysis of deoxyuridine triphosphate nucleotidohydrolase from Saccharomyces cerevisiae.

Deoxyuridine triphosphate nucleotidohydrolase (dUTPase) from Saccharomyces cerevisiae is essential for cell viability. It has been overexpressed in Escherichia coli and has been crystallized at 296 K using polyethylene glycol (PEG) 1500 as a precipitant. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 59.48, b = 138.54, c = 157.91 A, alpha = beta = gamma = 90 degrees. Two molecules of trimeric dUTPase from S. cerevisiae are present in the asymmetric unit, giving a crystal volume per protein mass (V(M)) of 3.36 A(3) Da(-1) and a solvent content of 63%. The diffraction limit of the crystals could be significantly extended by the crystal-annealing procedure. A set of native data extending to 2.7 A resolution has been collected at 100 K using synchrotron X-rays.

Crystallization↗

PubMed2001

Crystal structure of the MJ0490 gene product of the hyperthermophilic archaebacterium Methanococcus jannaschii, a novel member of the lactate/malate family of dehydrogenases.

The MJ0490 gene, one of the only two genes of Methanococcus jannaschii showing sequence similarity to the lactate/malate family of dehydrogenases, was classified initially as coding for a putative l-lactate dehydrogenase (LDH). It has been re-classified as a malate dehydrogenase (MDH) gene, because it shows significant sequence similarity to MT0188, MDH II from Methanobacterium thermoautotrophicum strain DeltaH. The three-dimensional structure of its gene product has been determined in two crystal forms: a "dimeric" structure in the orthorhombic crystal at 1.9 A resolution and a "tetrameric" structure in the tetragonal crystal at 2.8 A. These structures share a similar subunit fold with other LDHs and MDHs. The tetrameric structure resembles typical tetrameric LDHs. The dimeric structure is equivalent to the P-dimer of tetrameric LDHs, unlike dimeric MDHs, which correspond to the Q-dimer. The structure reveals that the cofactor NADP(H) is bound at the active site, despite the fact that it was not intentionally added during protein purification and crystallization. The preference of NADP(H) over NAD(H) has been supported by activity assays. The cofactor preference is explained by the presence of a glycine residue in the cofactor binding pocket (Gly33), which replaces a conserved aspartate (or glutamate) residue in other NAD-dependent LDHs or MDHs. Preference for NADP(H) is contributed by hydrogen bonds between the oxygen atoms of the monophosphate group and the ribose sugar of adenosine in NADP(H) and the side-chains of Ser9, Arg34, His36, and Ser37. The MDH activity of MJ0490 is made possible by Arg86, which is conserved in MDHs but not in LDHs. The enzymatic assay showed that the MJ0490 protein possesses the fructose-1,6-bisphosphate-activated LDH activity (reduction). Thus the MJ0490 gene product appears to be a novel member of the lactate/malate dehydrogenase family, displaying an LDH scaffold and exhibiting a relaxed substrate and cofactor specificities in NADP(H) and NAD(H)-dependent malate and lactate dehydrogenase reactions.

Allosteric Regulation↗

PubMed2001

Enhanced detection of right-to-left shunt through patent foramen ovale by transthoracic contrast echocardiography using harmonic imaging.

When the results of transesophageal echocardiography was regarded as the gold standard for detecting a patent foramen ovale (PFO) in 136 consecutive patients referred for evaluation of cardiac source of embolism, transthoracic harmonic imaging using saline contrast was superior to fundamental imaging in accuracy for detecting a PFO (sensitivity, 22.5%; specificity [p < 0.05] and sensitivity, 100%; specificity 100%, respectively.)

Adult↗

PubMed2001

MS-275, a histone deacetylase inhibitor, selectively induces transforming growth factor beta type II receptor expression in human breast cancer cells.

Transcriptional repression of the transforming growth factor (TGF)-1P type II receptor (TPRII) gene appears to be a major mechanism to inactivate TGF-beta responsiveness in many human cancers. Because histone acetylation/deacetylation plays a role in transcriptional regulation, we have examined the effect of MS-275, a synthetic inhibitor of histone deacetylase, in human breast cancer cell lines. MS-275 showed antiproliferative activity against all human breast cancer cell lines examined and induced TbetaRII mRNA, but not TGF-beta type I receptor mRNA. MS-275 caused an accumulation of acetylated histones H3 and H4 in total cellular chromatin. An increase in the accumulation of acetylated histones H3 and H4 was detected in the TbetaRII promoter after treatment with MS-275. However, the level of histone acetylation did not change in chromatin associated with the TGF-beta type I receptor gene. MS-275 treatment enhanced TGF-beta1-induced plasminogen activator inhibitor 1 expression. Thus, antitumor activity of MS-275 may be mediated in part through the induction of TbetaRII expression and consequent potentiation of TGF-beta signaling.

Acetylation↗

PubMed2001

Ictal automatisms with preserved responsiveness in a patient with left mesial temporal lobe epilepsy.

PURPOSE: To describe the possible mechanism of ictal automatisms with preserved responsiveness (APRs) in a patient with left mesial temporal lobe epilepsy, which had not been reported previously. METHODS: Ictal EEGs recorded from bilateral foramen ovale electrodes with scalp-sphenoidal electrodes were analyzed in respect to the ictal semiology. RESULTS: The patient had a right hemispheric language dominance in the dextral. Electroclinical analysis revealed that the onset of oroalimentary automatisms coincided with the involvement of the left mesial and lateral temporal structures by spreading ictal discharges. The ictal discharge spreading was limited to the ipsilateral hemisphere throughout the seizure, which explained the intact consciousness and preserved responsiveness of the patient. CONCLUSIONS: This case suggests that APRs take place in seizures originating from the nondominant temporal lobe, during which ipsilateral mesial and lateral temporal structures are diffusely involved without spreading to the contralateral side.

Adolescent↗

PubMed2001

Radionuclide cisternography in spontaneous intracranial hypotension with simultaneous leaks at the cervicothoracic and lumbar levels.

This case report clearly illustrates defined simultaneous cerebrospinal fluid leaks at the cervicothoracic and upper lumbar areas. A 53-year-old woman without a remarkable medical history was hospitalized for sudden onset of severe headache. The headache lasted more than 1 week and standing or sitting positions exaggerated the symptoms, although it was relieved when the patient was recumbent. Radionuclide cisternography was performed using 150 MBq (4 mCi) Tc-99m DTPA. It revealed two cerebrospinal fluid leaks from the cervicothoracic junction bilaterally and the left side of the upper lumbar area. Epidural blood patching was tried at the lumbar level (L1-L2) and showed only a transient effect. A second trial of this method at the level of C7-T1 performed 2 days later resulted in immediate improvement of the symptoms without recurrence. The simultaneous cerebrospinal fluid leaks were detected successfully with radionuclide cisternography using Tc-99m DTPA, which provided a useful guideline for treatment despite the limitations of delayed scanning.

Blood Patch, Epidural↗

PubMed2001

Crystallization and preliminary X-ray crystallographic analysis of the TM1442 gene product from Thermotoga maritima, a homologue of Bacillus subtilis anti-anti-sigma factors.

A 110-residue protein encoded by the TM1442 gene of Thermotoga maritima shows amino-acid sequence similarity to Bacillus subtilis anti-anti-sigma factors RsbV and SpoIIAA. It has been overexpressed in Escherichia coli and the recombinant protein exists primarily as both a monomer and a dimer in solution. The dimeric form has been crystallized using polyethylene glycol (PEG) 8000 as a precipitant. Native X-ray diffraction data have been collected at 100 K to 2.0 A resolution. The crystals are monoclinic, belonging to the space group P2(1), with unit-cell parameters a = 31.54 (13), b = 116.83 (37), c = 31.39 (7) A, alpha = 90, beta = 119.84 (9), gamma = 90 degrees. The asymmetric unit contains two monomers of the recombinant polypeptide, with a corresponding V(M) of 2.24 A(3) Da(-1) and a solvent content of 45.0%.

Bacillus subtilis↗

PubMed2001

Yonsei Stroke Registry. Analysis of 1,000 patients with acute cerebral infarctions.

BACKGROUND AND PURPOSE: The hospital-based stroke registry is a well-established method useful for understanding diverse clinical characteristics of stroke related to geographical, racial or environmental differences. We analyzed the data from 1,000 patients with acute cerebral infarctions registered with the Yonsei Stroke Registry (YSR) which is the first prospective hospital-based observational study in Korea. METHODS: All patients had cerebral infarctions and presented within 7 days of onset. CT or MRI was performed in all patients and a vascular imaging study (digital subtraction or magnetic resonance angiography) was conducted in 53.9% of the patients. Subtype classification was made through a consensus approach based on the strict application of TOAST criteria. RESULTS: The mean age of patients was 62 +/- 12 years, and 60.8% were males. Undetermined cause (UD) was the most frequent subtype (40.6%), which was followed by lacunar stroke (LS 21.5%), cardiac embolism (CE 18.3%), large-artery atherosclerosis (LAA 16.5%) and other determined causes (3.1%). Hypertension was found in 64.3%, smoking in 35.2%, diabetes mellitus in 26.9%, hypercholesterolemia in 24.1%, high hematocrit (> or = 50%) in 21.8%, clinically identified potential cardiac sources of embolism in 18.3%, a history of previous stroke in 22.0% and a history of previous transient ischemic attack in 4.7%. Recurrent stroke was associated with a higher number of risk factors (p < 0.001) and a higher incidence of LAA (p = 0.003) than the first stroke. Vertebrobasilar artery territorial infarction was found in 39.8%, which was associated with higher incidences of LAA and LS and a lower incidence of CE than carotid artery territorial lesions (p = 0.001). The 30-day mortality rate was 5.3% and cerebral herniation caused early death in 52%. CONCLUSION: The distribution of stroke subtypes in the YSR was largely comparable with that of western registries. The highest incidence of UD might be related to the strict application of TOAST criteria.

Aged↗

PubMed2001

Diffusion-weighted image and MR spectroscopic analysis of a case of MELAS with repeated attacks.

We report the clinical and MR manifestations of an 18 year-old girl with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome. Recurrent status epilepticus caused reversible cytotoxic edema on diffusion-weighted images (DWI). Initial and one month follow-up MR spectroscopy, after seizure control, showed some discrepancies in the ratio of metabolites. N-acetylaspartate (NAA) partially recovered (NAA/creatine (Cr) ratio: 1.27-->1.84). This was because of a normalization of decreased NAA due to cellular dysfunction as a result of status epilepticus. A low ratio of NAA/Cr due to abnormal mitochondria remained in the decreased state. Reversible NAA/Cr ratios in the acute lesion suggested that NAA reflects the neuronal function as well as the level of neuronal structural damage. The altered NAA/Cr ratio better correlated with the abnormal signal intensity area of T2-weighted images (T2WI) and DWI than the lactate (Lac)/Cr ratio. With conservative treatment with anti-epileptics not accompanied by coenzyme Q or sodium dichloroacetate, lactate persistently increased (Lac/Cr ratio: 1.01-->1.21) because of the continued production of lactate in cells with respiratory deficiency, which is the main pathology of MELAS.

Adolescent↗

PubMed2001

Mechanism of induction of transforming growth factor-beta type II receptor gene expression by v-Src in murine myeloid cells.

Transforming growth factor (TGF)-beta1 plays an important role during hematopoiesis. Previously, we had shown that the growth of a v-Src-transformed myeloid cell line was markedly more inhibited by TGF-beta treatment when compared with the wild-type myeloid cell line. To investigate the increased growth sensitivity of the v-Src-transformed myeloid cell line, 32D-src, to TGF-beta, we examined expression of the TGF-beta type II receptor (TGF-beta RII) gene in myeloid cell lines. Northem blot analysis showed that expression of approximately 8- and 6-kb species of TGF-beta RII transcripts was markedly increased in the 32D-src cell line. The expression of the TGF-beta RII promoter linked to a reporter gene was increased 23-fold by v-Src. DNA transfection and electrophoretic mobility shift assay revealed that v-Src induces TGF-beta RII promoter activity through an AP1/ATF2-like sequence (-219 to -172), ETS binding sites (+1 to +36), and the inverted CCAAT box (-81 to -77). Novel DNA-protein complexes with ETS binding sites are significantly increased in v-src-transformed cell lines compared with the control cell line. These results suggest that v-Src induces activity of the TGF-beta RII promoter through multiple elements by inducing expression of nuclear proteins interacting with these elements.

Animals↗

PubMed2000

Evaluation of ictal brain SPET using statistical parametric mapping in temporal lobe epilepsy.

An automated voxel-based analysis of brain images using statistical parametric mapping (SPM) is accepted as a standard approach in the analysis of activation studies in positron emission tomography and functional magnetic resonance imaging. This study aimed to investigate whether or not SPM would increase the diagnostic yield of ictal brain single-photon emission tomography (SPET) in temporal lobe epilepsy (TLE). Twenty-one patients (age 27.14 +/- 5.79 years) with temporal lobe epilepsy (right in 8, left in 13) who had a successful seizure outcome after surgery and nine normal subjects were included in the study. The data of ictal and interictal brain SPET of the patients and baseline SPET of the normal control group were analysed using SPM96 software. The t statistic SPM¿t¿ was transformed to SPM¿Z¿ with various thresholds of P<0.05, 0.005 and 0.001, and corrected extent threshold P value of 0.05. The SPM data were compared with the conventional ictal and interictal subtraction method. On group comparison, ictal SPET showed increased uptake within the epileptogenic mesial temporal lobe. On single case analysis, ictal SPET images correctly lateralized the epileptogenic temporal lobe in 18 cases, falsely lateralized it in one and failed to lateralize it in two as compared with the mean image of the normal group at a significance level of P<0.05. Comparing the individual ictal images with the corresponding interictal group, 15 patients were correctly lateralized, one was falsely lateralized and four were not lateralized. At significance levels of P<0.005 and P<0.001, correct lateralization of the epileptogenic temporal lobe was achieved in 15 and 13 patients, respectively, as compared with the normal group. On the other hand, when comparison was made with the corresponding interictal group, only 7 out of 21 patients were correctly lateralized at the threshold of P<0.005 and five at P<0.001. The result of the subtraction method was close to the single case analysis on SPM at P<0.05. However, at higher thresholds (P<0.005 and 0.001) the subtraction method was comparable to the SPM results only when individual ictal images were compared with the normal control group, and not when comparison was with the interictal group. It is concluded that SPM is an alternative diagnostic method for the localization or lateralization of the seizure focus in temporal lobe epilepsy and that interictal SPET could be omitted if a normal brain SPET database were to be established. The medical cost of seizure localization would thereby be reduced.

Adolescent↗

PubMed2000

Abnormal band of the lateral meniscus of the knee.

We report 2 cases of an abnormal band of the lateral meniscus of the knee joint. A 23-year-old man complained of mechanical symptoms in both knees and an arthroscopic procedure was performed. We found meniscal abnormalities in the both knees. A 20-year-old man sustained a posterior cruciate ligament injury. In the course of an arthroscopy for his torn posterior cruciate ligament, an abnormal band of the lateral meniscus was seen. It was characteristic that the upper abnormal band was loose and serpentine and connected at the posterior horn and the middle segment of the lower normal lateral meniscus. Arthroscopic resection of abnormal bands successfully eliminated the symptoms. Because of its characteristic appearance and bilaterality, it was evident that this abnormal band was a congenital anomaly.

Adult↗

PubMed2000

Topical and systemic anticoagulation in the treatment of absent or compromised venous outflow in replanted fingertips.

Adequate venous repair is not always possible in fingertip replantation. We have used topical and systemic anticoagulation for fingertip replantation to overcome venous congestion in cases without venous repair or in cases in which there is obstruction of a repaired vein. Our technique consists of continuous external bleeding via a stab incision on the paraungal area and dripping heparinized saline solution at the incision site to maintain external bleeding. From July 1985 to December 1993, 157 fingers in 140 patients with complete amputation of the fingertip were replanted at Korea University Guro Hospital. Of these, 74 fingers in 68 patients were managed by topical and systemic anticoagulation due to the impossibility of repair or obstruction of a repaired vein. The overall survival rate of the fingertip replantations was 76%; that of the topical and systemic anticoagulation group was 64%.

Administration, Topical↗