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Biomedical subjects

D W Seo

Publications and source records attributed to D W Seo.

At least 37 records · Page 2Linked to original sources
PubMed2000

Apicidin, a histone deacetylase inhibitor, inhibits proliferation of tumor cells via induction of p21WAF1/Cip1 and gelsolin.

Apicidin [cyclo(N-O-methyl-L-tryptophanyl-L-isoleucinyl-D-pipecolinyl -L-2-amino-8-oxodecanoyl)] is a fungal metabolite shown to exhibit antiparasitic activity by the inhibition of histone deacetylase (HDAC). In this study, we evaluated apicidin as a potential antiproliferative agent. Apicidin showed a broad spectrum of antiproliferative activity against various cancer cell lines, although with differential sensitivity. The antiproliferative activity of apicidin on HeLa cells was accompanied by morphological changes, cell cycle arrest at G1 phase, and accumulation of hyperacetylated histone H4 in vivo as well as inhibition of partially purified HDAC in vitro. In addition, apicidin induced selective changes in the expression of p21WAF1/Cip1 and gelsolin, which control the cell cycle and cell morphology, respectively. Consistent with increased induction of p21WAF1/Cip1, phosphorylation of Rb protein was markedly decreased, indicating the inhibition of cyclin-dependent kinases, which became bound to p21WAF1/Cip1. The effects of apicidin on cell morphology, expression of gelsolin, and HDAC1 activity in vivo and in vitro appeared to be irreversible, because withdrawal of apicidin did not reverse those effects, whereas the induction of p21WAF1/Cip1 by apicidin was reversible. Taken together, the results suggest that induction of histone hyperacetylation by apicidin is responsible for the antiproliferative activity through selective induction of genes that play important roles in the cell cycle and cell morphology.

3T3 Cells↗
PubMed2000

Mapping of functional organization in human visual cortex: electrical cortical stimulation.

OBJECTIVES: To investigate the pattern of functional organization in the human visual cortex through electrical cortical stimulation. METHODS: Electrical cortical stimulation was applied to the occipital cortex and adjacent cortices using subdural grid electrodes in 23 epilepsy patients. Diverse visual responses were recorded. These responses were divided into different categories according to the specific response modalities, such as form, color, and motion. Form visual responses were further subdivided into simple, intermediate, and complex responses. The cortical localization of subdural electrodes was identified using MRI-CT coregistration. The cortical distribution of different visual responses was projected into three-dimensional surface renderings of the brain. The distribution and frequency of subdural electrodes showing different visual responses were quantified by calculating the percentage of the number of electrodes showing one specific type of visual response at the corresponding anatomic region to the total number of electrodes in all brain regions that produced the same response. RESULTS: Simple form responses were obtained mostly at the occipital pole and the inferior occipital gyrus (47.4%) and the striate cortex (42.4%). Intermediate form responses occurred mainly on the peristriate cortex (52.5%) and the lateral occipital (28.0%) and fusiform gyri (19.5%). Complex forms were produced by stimulation of the basal temporo-occipital region (57.6%) and the lateral temporal or lateral temporo-occipital junctional region (42.4%). Color responses occurred on the basal occipital area, mostly at the fusiform (40.0%) and lingual gyri (36.0%). Moving sensations were evoked by stimulation of the basal temporo-occipital (28.4%) and the mesial parieto-occipital or temporo-parieto-occipital junctional regions (23.9%). CONCLUSIONS: Different modalities of vision, such as form, color, and moving sensation, appeared to be distributed and organized in different areas of the human visual cortex.

Adolescent↗
PubMed2000

The relationship between the angiographic findings and the clinical features of carotid artery plaque.

The purpose of this study was to investigate the histological characteristics of atheromatous carotid plaque, and to analyze the relationship between the angiographic findings and the clinical features. We retrospectively reviewed 55 cases of carotid endarterectomy for extracranial internal carotid artery stenosis, who were treated at our institute from January 1995 to December 1997. The histological examination included hematoxylin-eosin staining, Masson-trichrome staining, and immunostaining for antismooth muscle antibody and anti-CD68 antibody. The main compositions of the carotid plaque included synthetic type vascular smooth muscle cells and extracellular matrix. The histological findings showed ulceration in 49 (89.1%) cases, calcium deposits in 42 (76.4%) cases, and an inflammatory reaction in 44 (80.0%) cases. Neurological abnormalities were strongly associated with plaque ulceration (P = 0.045) and an inflammatory reaction (P = 0.013), whereas no correlation existed regarding calcium deposits (P = 0.173). The angiographic findings showed ulceration in 46 (83.6%) cases. Plaque ulceration in the angiography findings showed no statistically significant correlation with the histologic findings (P = 0.410) and preoperative neurologic abnormalities (P = 0.059). All of the atherosclerotic risk factors such as hypertension, smoking, diabetes mellitus, hyperlipidemia, and myocardial infarction had no statistically significant correlation with the histological features of the carotid plaque. In conclusion, the main compositions of carotid plaque were synthetic-type vascular smooth muscle cells and extracellular matrix. The histological ulceration and inflammatory reaction of the plaque showed a statistically significant correlation with the preoperative neurologic symptoms, whereas no correlation was seen in the calcium deposits. Angiographic ulceration showed no correlation with the histological findings or preoperative neurologic abnormalities. In addition, the histological findings showed no correlation with the atherosclerotic risk factors.

Aged↗
PubMed2000

Ipsilesional versus contralesional neglect depends on attentional demands.

Right hemisphere injuries often produce contralesional hemispatial neglect (CN). In contrast to CN, some patients with right hemisphere damage can also show so-called ipsilesional neglect (IN). Previous reports found that patients tend to show IN on line bisection tasks but CN on other tasks such as target cancellation. To learn why these two tasks induce different spatial biases in patients with right hemisphere injury, conventional (i.e. solid) line bisection was compared with two novel bisection tasks consisting of horizontally aligned strings of characters. The subjects' task was to mark a target character that was at or closest to the true midpoint of the simulated line. Four of the 5 patients showed a dissociation whereby IN occurred for solid lines while CN was observed on character lines. The two patients assessed with an antisaccade paradigm showed a "visual grasp" for leftward stimuli. The present results suggest that neglect on line bisection may reflect two opposing forces, an approach behavior or "visual grasp" toward left hemispace and an attentional bias toward right hemispace.

Adult↗
PubMed2000

An endogenous proteinacious inhibitor in porcine liver for S-adenosyl-L-methionine dependent methylation reactions: identification as oligosaccharide-linked acyl carrier protein.

A proteinacious inhibitor of S-adenosyl-L-methionine (AdoMet)-dependent transmethylation reactions was purified to homogeneity from porcine liver by size exclusion chromatography and FPLC. The molecular weight of the inhibitor was 12,222 Da. A 7400 Da polypeptide fragment of the purified inhibitor was sequenced by matrix-associated laser desorption ionization; time-of-flight MS, and was found to be identical with the known sequence of spinach acyl carrier protein (ACP). Although the remainder of the molecule was not clearly defined, 1H and H-H correlation of spectroscopy (COSY) NMR analysis revealed the presence of an oligosaccharide with alpha-glycosidic linkage. The purified oligosaccharide-linked ACP inhibited several AdoMet-dependent transmethylation reactions such as protein methylase I and II. S-farnesylcysteine O-methyltransferase, DNA methyltransferase and phospholipid methyltransferase. Protein methylase II was inhibited with a Ki value of 2.4 x 10(-3) M in a mixed inhibition pattern, whereas a well-known competitive product inhibitor S-adenosyl-L-homocysteine (AdoHcy) had Ki value of 6.3 x 10(-6) M. Commercially available active ACP fragments (65-74) and ACP from Escherichia coli had less inhibitory activity toward S-farnesylcysteine O-methyltransferase than the purified inhibitor. The biological significance of this oligosaccharide-linked ACP which has two seemingly unrelated functions (inhibitor for transmethylation and fatty acid biosynthesis) remains to be elucidated.

Acyl Carrier Protein↗
PubMed2000

Detection of Helicobacter pylori DNA in human biliary tree and its association with hepatolithiasis.

Recently, several authors have reported that Helicobacter pylori DNA has been found in human bile. The aim of this study is to investigate the presence of H. pylori in the biliary tree of Koreans, including the bile, biliary epithelium, and gallstones. This study analyzed intrahepatic bile, bile duct tissue, and gallstones from 43 patients with hepatobiliary disease (PTCS group), gallbladder bile and tissue from 23 patients with gallbladder disease (CCT group), and eight patients without hepatobiliary disease (control group). H. pylori was examined by PCR with two different primers. PCR was positive in 4/43 (9.3%) by 26 kDa protein antigen primer and in 5/43 (11.6%) by urease A gene primer in bile from the PTCS group. However, in intrahepatic duct tissue, PCR was positive in only one case. PCR of gallbladder bile, tissue, and intrahepatic duct stones was negative. Upon intrahepatic bile analysis, the pH was significantly lower in PCR-positive than in negative cases (P < 0.05). In conclusion, H. pylori DNA may be present in the bile when there are certain environmental changes, such as lowered pH; however, H. pylori does not colonize the bile duct epithelium. We could find no pathogenetic role for H. pylori in the formation of hepatolithiasis.

Adult↗
PubMed2000

Mucin-hypersecreting bile duct tumor characterized by a striking homology with an intraductal papillary mucinous tumor (IPMT) of the pancreas.

BACKGROUND AND STUDY AIMS: The mucin-hypersecreting bile duct tumor, which closely resembles an intraductal papillary mucinous tumor (IPMT) of the pancreas, is rare, and its clinical features are not well known. We report our experience of nine patients with this type of tumor, and analyze the data in order to elucidate its clinicopathologic characteristics. PATIENTS AND METHODS: Between 1995 and 1998, nine consecutive patients (four men, five women; mean age 54) who were diagnosed as having a mucin-hypersecreting bile duct tumor were enrolled in this study. RESULTS: Recent or previous attacks of biliary pain and acute cholangitis were reported by most of the patients. Characteristics included a widely open ampulla of Vater with extrusion of mucin, and a diffuse dilated intrahepatic and extrahepatic bile duct with amorphous filling defects on cholangiogram. On cholangioscopic examination, a papillary mass or minute mucosal lesion was found in the dilated bile duct containing thick viscid mucin. Nine patients were referred for an operation, and curative resection was performed in eight of them. Using histologic examination, well differentiated adenocarcinoma in the background of benign hyperplasia and adenoma was documented in all patients except one, who showed pure adenoma. CONCLUSION: The mucin-hypersecreting bile duct tumor can be characterized by a striking homology with IPMT of the pancreas in clinical, radiologic, and pathologic features.

Adenocarcinoma, Mucinous↗
PubMed2000

Safety and usefulness of percutaneous transhepatic cholecystoscopy examination in high-risk surgical patients with acute cholecystitis.

BACKGROUND: The aim of the present study was to evaluate the diagnostic and therapeutic usefulness of percutaneous transhepatic cholecystoscopy in high-risk surgical patients with acute cholecystitis. METHODS: Between January 1992 and June 1998, there were 33 consecutive patients who underwent percutaneous transhepatic cholecystostomy and subsequent percutaneous transhepatic cholecystoscopy for the management of acute cholecystitis. RESULTS: Percutaneous transhepatic cholecystostomy and subsequent percutaneous transhepatic cholecystoscopy were successfully accomplished in all 33 patients. During percutaneous transhepatic cholecystoscopy, minor complications (2 episodes of minor bleeding during electrohydraulic lithotripsy, 2 of tube dislodgement, and 1 of bile leakage to peritoneum) occurred in 5 patients. Percutaneous transhepatic cholecystoscopy revealed gallstones in 26 cases, sludge ball in 3, gallbladder carcinoma in 3, and 1 case of clonorchiasis related with acute cholecystitis. The 3 gallbladder cancers which were not identified radiologically were found incidentally during percutaneous transhepatic cholecystoscopy. For the 26 patients with gallstones, percutaneous transhepatic cholecystoscopy and concomitant stone removal were successful in 1 to 4 consecutive sessions (mean 2.2 sessions). Gallstones recurred in 3 of 22 patients (14%) during the mean follow-up period of 27 months. All of them remain asymptomatic. CONCLUSION: Percutaneous transhepatic cholecystostomy may be justified in the management of acute cholecystitis in selected patients with high surgical risk.

Acute Disease↗
PubMed2000

A new strategy to predict the neoplastic polyps of the gallbladder based on a scoring system using EUS.

BACKGROUND: A new method to predict neoplastic polyps of the gallbladder using a scoring system based on five endoscopic ultrasonography (EUS) variables is presented. METHODS: EUS data from patients with gallbladder polyps who were to undergo cholecystectomy were used for the construction of an EUS scoring system in polyps between 5 and 15 mm in diameter (reference group). The EUS scoring system developed from those patients was applied to other patients (validation group). RESULTS: In the reference group, size was the most significant predictor of neoplastic polyp. All polyps 5 mm or less in diameter were non-neoplastic and 94% of polyps of greater than 15 mm were neoplastic in the reference group. For polyps between 5 and 15 mm in diameter, the area under the receiver-operating characteristic curves (ROC) plots for the endoscopic scoring system was significantly greater than that under the ROC plots for polyp size alone (p < 0.01). In the validation group, the risk of neoplastic polyp was significantly higher for polyps with a score of 6 or greater compared with those with a score of less than 6 (p < 0.01). CONCLUSIONS: Our data show that a score based on five EUS variables identifies those patients at risk of neoplasia when polyps are between 5 and 15 mm in diameter. (Gastrointest Endosc 2000;52:372-9).

Adult↗
PubMed2000

Cholangioscopic findings in bile duct tumors.

BACKGROUND: Cholangioscopy has been used in the treatment of bile duct stones and the diagnosis of various bile duct tumors. However, the cholangioscopic characteristics of the various types of bile duct tumors have not been clearly described. We analyzed the results of cholangioscopic examinations and classified the findings according to tumor histology. METHODS: Cholangioscopic findings from 111 patients with benign or malignant bile duct tumors were reviewed. The mucosal changes, the presence of neovascularization, and the patterns of luminal narrowing were analyzed and compared with the histologic diagnosis. RESULTS: Bile duct adenocarcinoma can be classified into 3 different types according to the cholangioscopic findings: nodular, papillary, and infiltrative. Bile duct adenoma, hepatocellular carcinoma and other types of bile duct cancer such as mucin-hypersecreting cholangiocarcinoma, biliary cystadenocarcinoma, and squamous cell carcinoma also presented unique cholangioscopic characteristics. CONCLUSIONS: Bile duct tumors exhibit characteristic cholangioscopic findings and cholangioscopy seems to be useful for differential diagnosis.

Bile Duct Neoplasms↗
PubMed2000

Tumor vessel: a valuable cholangioscopic clue of malignant biliary stricture.

BACKGROUND: An irregularly dilated and tortuous vessel, the so-called tumor vessel, is considered to be one of the cholangioscopic features that suggest biliary malignancy. This is a prospective analysis of the presence of a tumor vessel as a finding that discriminates between benign and malignant biliary strictures. METHODS: From August 1997 to August 1998, a total of 63 patients with biliary strictures diagnosed with endoscopic retrograde cholangiography or percutaneous transhepatic cholangiography obtained during percutaneous transhepatic biliary drainage tube placement were included in this study. Strictures were characterized as benign or malignant based on the observation of tumor vessels. The results were compared with those of percutaneous transhepatic cholangiography-guided biopsy and final diagnosis. RESULTS: Forty-one patients were confirmed to have malignant strictures and 22 had benign biliary strictures. Cancer was confirmed by histopathologic evaluation of biopsies in 33 of 41 patients with malignancy (80.4%). Tumor vessel was seen in 25 of 41 patients with malignancy (61%). No patients with benign stricture had tumor vessels. Of the 8 patients with negative percutaneous transhepatic cholangioscopy-guided biopsies but with a final diagnosis of malignancy, 6 had tumor vessels. Combining the observation of tumor vessel and percutaneous transhepatic cholangiography-guided biopsy resulted in a diagnosis of malignancy in 39 of 41 patients (96%) and significantly increased the rate of preoperative diagnosis when compared with percutaneous transhepatic cholangiography-guided biopsy or presence of tumor vessel alone (p<0.05). CONCLUSION: The presence of tumor vessel may be a valuable cholangioscopic finding that indicates the presence of a malignant biliary stricture. The combination of tumor vessel observation and percutaneous transhepatic cholangiography-guided biopsy may improve the preoperative diagnosis of malignancy.

Adult↗
PubMed2000

Correlation of temporal lobe glucose metabolism with the Wada memory test.

PURPOSE: The goal of the present study was to examine the relationship of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) and the Wada memory test in lateralizing memory dominance and epileptic focus. METHODS: FDG-PET and the Wada test were performed in 18 patients with temporal lobe epilepsy (TLE). The asymmetry indices of FDG-PET (PET-AI) were calculated in mesial, polar, anterolateral, midlateral, and posterolateral regions of the temporal lobe, and those of Wada memory test (Wada-AI) were obtained as well. RESULTS: The Wada-AI was significantly correlated with PET-AI in mesial (r = 0.67, p = 0.003), polar (r = 0.55, p = 0.019), anterolateral (r = 0.55, p = 0.019), and midlateral (r = 0.51, p = 0.031) regions of the temporal lobe. However, after a linear regression analysis, PET-AI of only the mesial temporal region was significantly correlated with Wada-AI (p = 0.008). Wada-AI could correctly lateralize the seizure focus in 90% of the left TLE and 75% of the right TLE patients. The PET-AI of the mesial temporal region showed the highest sensitivity of seizure lateralization (80% of left TLE and 87.5% of right TLE). PET-AI of other temporal regions had lower sensitivities (50-80% of left TLE, 20-75% of right TLE). One or two patients showed false seizure lateralization by PET-AI on each temporal region. CONCLUSIONS: Although FDG-PET hypometabolism is observed at both mesial and lateral regions of the temporal lobe in mesial TLE, mesial temporal region appeared to be a dominant and leading area for lateralizing Wada memory dominance and epileptic focus.

Adolescent↗
PubMed2000

Contralateral EEG slowing and amobarbital distribution in Wada test: an intracarotid SPECT study.

PURPOSE: To relate the occurrence of contralateral electroencephalogram slowing (CES) to amobarbital distribution, we performed electroencephalogram (EEG) monitoring and intracarotid single photon emission computed tomography (SPECT) during an intracarotid amobarbital procedure (IAP). METHODS: IAP was performed on 22 patients with temporal lobe epilepsy. CES was defined as the occurrence of significant EEG slowing on the contralateral hemisphere (>50% of the ipsilateral hemisphere slowing) after amobarbital injection. To map the distribution of the amobarbital, we injected a mixture of amobarbital and (99m)technetium-ethylcysteinate dimer (99mTc-ECD) into the internal carotid artery and performed a brain SPECT 2 h later. In the SPECT images, regions of interest were determined by ipsilateral and contralateral anterior cerebral artery territories (iACA, cACA), ipsilateral and contralateral middle cerebral artery territories (iMCA, cMCA), and ipsilateral and contralateral posterior cerebral artery territories (iPCA, cPCA), as well as ipsilateral and contralateral anterior and posterior mesial temporal regions (iAMT, cAMT, iPMT, cPMT). The perfusion of amobarbital was interpreted visually in each region. RESULTS: Amobarbital was distributed in the iMCA in all the patients; in the iACA in 20 (90.9%) patients; in the iAMT in 14 (63.5%); and in the iPCA and iPMT in only two (9.1%). CES was observed in 13 (59.1%) patients. Cross-perfusion of amobarbital in limited areas of the cACA were observed in only four of 13 patients. Wada retention memory scores (WRMS) showed no significant difference between the CES- (n = 9) and CES+ (n = 13) groups. CONCLUSIONS: Amobarbital rarely perfused the iPCA territory and the iPMT region and was rarely delivered to the contralateral hemisphere. The occurrence of CES was not related to the cross-perfusion of amobarbital. CES appears to be produced by a transient functional disconnection from the ipsilateral hemisphere.

Adolescent↗