Biomedical subjects

Seung-Hwan Lee

Publications and source records attributed to Seung-Hwan Lee.

At least 19 recordsLinked to original sources

PubMed2007

Hyperglycemia and hyperinsulinemia have additive effects on activation and proliferation of pancreatic stellate cells: possible explanation of islet-specific fibrosis in type 2 diabetes mellitus.

Pancreatic islet fibrosis observed in Type 2 diabetes is one of the major factors leading to progressive beta-cell loss and dysfunction. Despite its importance, the mechanism of islet-restricted fibrogenesis associated with pancreatic stellate cell (PSC) activation and proliferation remains to be defined. Therefore, we studied whether the islet-specific environment represented by hyperglycemia and hyperinsulinemia had additive effects on the activation and proliferation of cultured rat PSCs. Cells were stimulated to activate and proliferate with glucose and insulin, either individually or concomitantly. Both stimuli promoted PSC proliferation and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation independently, but an additive effect was also demonstrated. Blockade of ERK signaling by the mitogen-activated protein kinase kinase (MEK) inhibitor, U0126, suppressed both glucose- and insulin-induced ERK 1/2 phosphorylation and PSC proliferation. Glucose and insulin-induced ERK 1/2 phosphorylation also stimulated connective tissue growth factor gene expression. Thus, hyperglycemia and hyperinsulinemia are two crucial mitogenic factors that activate and proliferate PSCs, and the presence of both states will amplify this response.

Animals↗

PubMed2007

Factors predictive of cardiac events and restenosis after sirolimus-eluting stent implantation in small coronary arteries.

OBJECTIVES: Predictors of cardiac events and restenosis after sirolimus-eluting stent (SES) implantation in small coronary arteries were evaluated. BACKGROUND: Although SES implantation has markedly reduced the risk of restenosis, small vessel disease remains a major cause of SES failure. METHODS: We prospectively investigated the factors predictive of cardiac events and restenosis in 1,092 consecutive patients who received SES implantation for 1,269 lesions in small coronary arteries (< or = 2.8 mm). Follow-up angiography at 6 months was performed in 751 patients with 889 lesions (follow-up rate 70.3%). RESULTS: Restenosis (diameter stenosis > or = 50%) was angiographically documented in 65 patients with 77 lesions (8.7%): 55 focal (71.4%), 8 diffuse (10.4%), 2 diffuse proliferative (2.6%), and 12 total (15.6%). Lesion length, stent length, reference artery size, and in-stent restenotic lesions were univariate predictors of restenosis. By multivariate analysis, lesion length (OR 1.04; 95% CI 1.02-1.05; P < 0.001) and in-stent restenotic lesions (OR 3.38; 95% CI 1.80-6.35; P < 0.001) were significant independent predictors of restenosis. During follow-up (23.2 +/- 7.9 months), there were 17 deaths (5 cardiac and 12 noncardiac), 5 nonfatal Q-wave myocardial infarctions, and 42 target lesion revascularizations. The cumulative probability of survival without major adverse cardiac events (MACE) was (96.6 +/- 0.6)% at 1 year and (95.1 +/- 0.7)% at 2 years. In multivariate analysis, lesion length (HR 1.04; 95% CI 1.01-1.07; P = 0.004) and in-stent restenotic lesions (HR 3.29; 95% CI 1.58-6.86; P = 0.001) were independently related to MACE. CONCLUSIONS: SES implantation in small coronary arteries is safe and effective, with lesion length having a major impact on restenosis and MACE.

Adult↗

PubMed2006

The feasibility of percutaneous transradial coronary intervention for chronic total occlusion.

We evaluated the feasibility of the transradial coronary intervention (TRCI) in 85 consecutive patients with chronic total occlusion (CTO). Clinical, angiographic and procedural factors were compared between the success and failure groups. An overall success rate of 65.5% (57 of 87 lesions) was achieved with TRCI, and the most common cause of failure was an inability to pass the lesion with a guidewire. A multivariate analysis demonstrated that the most significant predictor of failure was the duration of occlusion (OR 1.064 per month, 95% CI 1.005 to 1.126, p = 0.03). The procedural success rate improved with use of new-generation hydrophilic guidewires. The 6 Fr guiding catheters were used in the majority of the 70 cases (81%). Five cases were crossed over to a femoral artery approach due to engagement failure of the guiding catheter into the coronary ostium because of severe subclavian tortuosity and stenosis in two cases, radial artery looping in one case, and poor guiding support in two cases. There were no major entry site complications. In conclusion, the radial artery might be a feasible vascular route in coronary interventions for CTO, with comparable procedural success and no access site complications.

Angioplasty, Balloon, Coronary↗

PubMed2006

Weight gain associated with the alpha2a-adrenergic receptor -1,291 C/G polymorphism and olanzapine treatment.

Weight gain can be an adverse effect of antipsychotics and is an important factor for long-term health and treatment compliance. Many reports have shown that the alpha(2)-adrenergic receptor may be related to eating behaviors or lipolytic activities, both associated with body weight change. We hypothesized that there might be a relationship between the alpha(2a)-adrenergic receptor -1,291 C/G polymorphism and olanzapine-induced weight gain. A group of 62 Korean schizophrenic patients participated in a study; weight and height measurements were obtained prior to starting olanzapine and measured again after long-term treatment. Genotyping for the -1291 C/G polymorphism was performed on all participants. Body weight changes from baseline to endpoint were significantly associated with genotypes (P = 0.028). The frequency of the G allele was significantly higher in subjects who had severe weight gain (defined as a more than 10% weight gain from baseline) compared to subjects who did not have extreme weight gain (less than 10% weight gain from baseline) (X(2) = 6.120, P = 0.013; OR = 2.58, 95% CI = 1.21-5.51). Therefore, the findings from this study support a relationship between the -1291 C/G polymorphism of the alpha(2a)-adrenergic receptor and weight gain in Korean schizophrenic patients receiving olanzapine treatment.

Adult↗

PubMed2006

Confirming single nucleotide polymorphisms from expressed sequence tag datasets derived from three cattle cDNA libraries.

Using the Phred/Phrap/Polyphred/Consed pipeline established in the National Livestock Research Institute of Korea, we predicted candidate coding single nucleotide polymorphisms (cSNPs) from 7,600 expressed sequence tags (ESTs) derived from three cDNA libraries (liver, M. longissimus dorsi, and intermuscular fat) of Hanwoo (Korean native cattle) steers. From the 7,600 ESTs, 829 contigs comprising more than two EST reads were assembled using the Phrap assembler. Based on the contig analysis, 201 candidate cSNPs were identified in 129 contigs, in which transitions (69%) outnumbered transversions (31%). To verify whether the predicted cSNPs are real, 17 SNPs involved in lipid and energy metabolism were selected from the ESTs. Twelve of these were confirmed to be real while five were identified as artifacts, possibly due to expressed sequence tag sequence error. Further analysis of the 12 verified cSNPs was performed using the program BLASTX. Five were identified as nonsynonymous cSNPs, five were synonymous cSNPs, and two SNPs were located in 3'-UTRs. Our data indicated that a relatively high SNP prediction rate (71%) from a large EST database could produce abundant cSNPs rapidly, which can be used as valuable genetic markers in cattle.

Animals↗

PubMed2006

Quantitative EEG and low resolution electromagnetic tomography (LORETA) imaging of patients with persistent auditory hallucinations.

Electrophysiological studies have demonstrated gamma and beta frequency oscillations in response to auditory stimuli. The purpose of this study was to test whether auditory hallucinations (AH) in schizophrenia patients reflect abnormalities in gamma and beta frequency oscillations and to investigate source generators of these abnormalities. This theory was tested using quantitative electroencephalography (qEEG) and low-resolution electromagnetic tomography (LORETA) source imaging. Twenty-five schizophrenia patients with treatment refractory AH, lasting for at least 2 years, and 23 schizophrenia patients with non-AH (N-AH) in the past 2 years were recruited for the study. Spectral analysis of the qEEG and source imaging of frequency bands of artifact-free 30 s epochs were examined during rest. AH patients showed significantly increased beta 1 and beta 2 frequency amplitude compared with N-AH patients. Gamma and beta (2 and 3) frequencies were significantly correlated in AH but not in N-AH patients. Source imaging revealed significantly increased beta (1 and 2) activity in the left inferior parietal lobule and the left medial frontal gyrus in AH versus N-AH patients. These results imply that AH is reflecting increased beta frequency oscillations with neural generators localized in speech-related areas.

Adult↗

PubMed2006

Acaricidal activities of paeonol and benzoic acid from Paeonia suffruticosa root bark and monoterpenoids against Tyrophagus putrescentiae (Acari: Acaridae).

The acaricidal activities of paeonol (2'-hydroxy-4'-methoxyacetophenone) and benzoic acid identified in the root bark of tree peony, Paeonia suffruticosa Andrews, against copra mite, Tyrophagus putrescentiae (Schrank), adults were examined using direct contact and vapour phase toxicity bioassays and compared with those of cinnamyl acetate, cinnamyl alcohol and 37 monoterpenoids as well as the acaricides benzyl benzoate, dibutyl phthalate and N,N-diethyl-m-toluamide (DEET). Based on LD(50) values in fabric piece contact toxicity bioassays, the acaricidal activities of benzoic acid (4.80 microg cm(-2)) and paeonol (5.29 microg cm(-2)) were comparable to that of benzyl benzoate (4.46 microg cm(-2)) but more pronounced than those of DEET (30.03 microg cm(-2)) and dibutyl phthalate (25.23 microg cm(-2)). In vapour phase toxicity bioassays, paeonol and benzoic acid were much more effective in closed containers than in open ones, indicating that the effects of these compounds were largely due to action in the vapour phase. As judged by 24 h LD(50) values, (1S)-(-)-verbenone (7.42 mg per disc) was the most toxic fumigant, followed by (1S)-(-)-camphor, (S)-(+)-carvone, (R)-(-)-linalool and (+/-)-camphor (10.45-18.18 mg). Potent fumigant toxicity was also observed with paeonol, (2S,5R)-(-)-menthone, (+/-)-citronellal, benzoic acid, (1S,4R)-(-)-alpha-thujone and (R)-(+)-pulegone (25.10-34.63 mg). Neither benzyl benzoate, DEET nor dibutyl phthalate caused fumigant toxicity. Paeonia root bark-derived materials, particularly paeonol and benzoic acid, as well as the monoterpenoids described, merit further study as potential acaricides or as leads for the control of T. putrescentiae.

Acetophenones↗

PubMed2006

Effects of ERCC1 expression in peripheral blood on the risk of head and neck cancer.

Squamous cell carcinoma of the head and neck (SCCHN) accounted for 3.5% of all cancers registered in Korea during 2001. Although tobacco smoking and alcohol consumption are known risk factors of SCCHN, only a small fraction of the populations exposed to tobacco or alcohol develop SCCHN. Therefore, differences in the susceptibility of SCCHN with respect to DNA repair and xenobiotic metabolisms have focused upon attempts to determine the causes of SCCHN. Here, we investigated factors that affect ERCC1 mRNA expression in peripheral blood. The study subjects were all Koreans (67 patients and 73 control subjects); 72.9% of all subjects were male; 68.4% were current or former smokers; and 62.4% were current or former alcohol drinkers. We also studied the association between ERCC1 mRNA expression and the C8092A polymorphism of ERCC1, and found lower ERCC1 mRNA expression in SCCHN patients than in controls (P<0.01). In the present study, we found that ERCC1 C8092A polymorphism is not related to the risk of SCCHN or expression of ERCC1 mRNA. In addition, we found a positive association between ERCC1 mRNA expression in peripheral blood and tumour tissues and inverse associations between ERCC1 mRNA expression and age or the number of cigarettes smoked. Therefore, our study suggests that ERCC1 mRNA expression is reduced by age and smoking and has a weak effect on SCCHN risk as compared with the effects of age and tobacco-smoking expression.

Adult↗

PubMed2006

Expression of RANKL and OPG in middle ear cholesteatoma tissue.

OBJECTIVES: The objective of this study was to investigate how the expression of the RANK-RANKL-OPG system mediates the formation and differentiation of osteoclasts and causes bone resorption in cholesteatoma. METHODS: An immunohistochemical analysis was carried out in 22 cholesteatoma tissues obtained during middle ear surgery and 15 normal postauricular skin tissues to examine the expression of RANKL and OPG. RESULTS: All 22 cases of cholesteatoma and the 15 cases of normal postauricular skin expressed RANKL and OPG. The count and rate of RANKL-positive cells in cholesteatoma was significantly higher than in normal postauricular skin. The count and rate of OPG-positive cells in normal postauricular skin was significantly higher than in cholesteatoma. The ratio of the positive expression rates of RANKL and OPG in cholesteatoma was statistically higher than in normal postauricular skin. CONCLUSIONS: We provide evidence suggesting that RANKL, which activates osteoclasts, plays a significant role in the mechanism of bone destruction in cholesteatoma, and that the ratio of RANKL to OPG may be a reliable indicator of bone destruction in cholesteatoma.

Biomarkers↗

PubMed2005

Sirolimus- versus paclitaxel-eluting stent implantation for unprotected left main coronary artery stenosis.

We performed this study in order to compare the immediate and mid-term outcomes of sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES) in lesions of the unprotected left main coronary artery (LMCA). We assessed 54 patients from 5 centers who had undergone unprotected LMCA stenting (35 SES and 19 PES). The procedural success rates were 100 and 95%, respectively, in the SES and PES patients (p = 0.19). At the 6-month clinical follow-up, the event-free probability was 100% in the SES group, and 88% in the PES group (p = 0.07). At the 6-month angiographic follow-up (n = 24), the SES group exhibited a slightly lower late loss than did the PES group (0.24 +/- 0.44 vs. 0.65 +/- 0.60 mm, p = 0.09), and the restenosis rates were 8 and 9% (p = 0.94) in the SES and PES patients, respectively. In conclusion, both groups exhibited excellent in-hospital and 6-month outcomes with no significant differences between them.

Adult↗

PubMed2005

Anatomical consideration of the radial artery for transradial coronary procedures: arterial diameter, branching anomaly and vessel tortuosity.

BACKGROUND: The radial artery is currently regarded as a useful vascular access site for coronary procedures. Adequate anatomical information of the radial artery should be helpful in performing the transradial coronary procedure. Therefore, we tried to evaluate the size of radial artery, the incidence and clinical significance of anomalous branching patterns and tortuosity of the radial artery related with transradial coronary procedure. MATERIALS AND METHOD: In 1191 cases, mean radial arterial diameter (RAD) was measured before and after the procedure using a two-dimensional ultrasound and retrograde radial artery angiography was performed before the transradial coronary procedure in all patients. Branching anomaly, tortuosity of the radial artery and procedural characteristics including procedure times and local vascular complications were analyzed. RESULTS: The mean RAD was 2.60 +/- 0.41 mm by two-dimensional ultrasound: 2.69 +/- 0.40 mm in men and 2.43 +/- 0.38 mm in women (p < 0.001). Radial artery occlusion occurred in 0.6% in coronary angiography and 1.4% in coronary intervention. In multivariate analysis, coronary intervention was significantly related to the radial artery occlusion (p = 0.048). Anomalous branching of upper extremity artery was found in 38 cases (3.2%); high origin of the radial artery was most frequent in 28 cases (2.4%). Tortuosity of radial and brachial artery was found in 67 of 50 cases (4.2%). Most common forms of tortuosity were S-shape in 21 cases (31.3%) and Omega-shape in 21 cases (31.3%). And most common site of radial artery tortuosity was proximal third of antecubital fossa (35 cases, 52.2%). Prolonged procedure times and cross-overs to other arteries were related with tortuosity of the radial artery, but not with anomalous branching. CONCLUSION: In our study, radial artery diameter was larger than the outer diameter of 5Fr sheath in 82.7% for transradial coronary procedure. Radial artery occlusion was associated with coronary intervention using larger size sheath than diagnostic angiography using 5Fr sheath. The incidence in branching anomaly and tortuosity of radial artery was not rare in our study. Radial artery tortuosity was associated with old age and prolonged procedure time.

Catheterization, Peripheral↗

PubMed2005

Broken guidewire fragment in the radio-brachial artery during transradial sheath placement: percutaneous retrieval via femoral approach.

A case in which a 0.014" wire was broken during the sheath placement in the radial artery for transradial coronary procedure is described here, and a successful retrieval of it using conventional methods is also described. Through the left femoral artery, the 6 Fr guiding catheter was advanced down to the tip of the broken wire at the brachial artery, and the distal part of the broken guidewire was captivated into the guiding catheter. By inflating the balloon catheter inside of the guiding catheter, seized broken guidewire between the inflated balloon and the guiding catheter was removed successfully by withdrawing the whole system en bloc.

Aged↗

PubMed2005

Percutaneous coronary stenting in guide-induced aortocoronary dissection: angiographic and CT findings.

We report here on a case of accidental aortocoronary dissection that occurred during the engagement of a guiding catheter. This resulted in an antegrade dissection into the right coronary artery, and a retrograde extension of the dissection into the Sinus of Valsalva and the ascending aorta up to the aortic arch. It was successfully treated with a stent deployment at the RCA ostium; this restored optimal coronary blood flow and there was a complete resolution of the aortic dissection as was documented by coronary angiography and the follow-up CT scan.

Aged↗

PubMed2005

No association between the tryptophan hydroxylase gene polymorphism and major depressive disorders and antidepressant response in a Korean population.

The serotonergic neurotransmitter system has been implicated in major depressive disorder (MDD) and appears to be the target of a variety of antidepressants. Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in serotonin biosynthesis, and selective serotonin re-uptake inhibitors exert their activity enhancing the general serotonergic tone. The goal of this study was to investigate whether the A218C polymorphism of the TPH gene is associated with MDD or antidepressant response. All patients were evaluated at the start and in the eighth week of using the 21-item Hamilton Depression Rating Scale. Genotyping was analyzed with polymerase chain reaction. There were no significant differences in genotypes and allele frequencies between the MDD patients (n = 93) and the control group (n = 127) and in the antidepressant response among TPH gene variants. Results suggest that the A218C polymorphism of the TPH gene does not play a major role in pathogenesis in MDD and does not serve as a modulator of antidepressant activity.

Adult↗

PubMed2005

Association between the 5-HT6 receptor C267T polymorphism and response to antidepressant treatment in major depressive disorder.

The purpose of the present study was to determine if a 5-HT6 receptor polymorphism is associated with antidepressant treatment response in major depressive disorder (MDD). Ninety-one patients with MDD, compared with 127 normal control subjects, were evaluated after an 8-week treatment period. An association analysis revealed no differences in genotype and allele distribution between patients with MDD and normal control subjects. However, there were significant differences in the treatment response in some Hamilton Depression Rating Scale (HAM-D) scores (sleep, activity, somatic anxiety, and total) between genotypes. Moreover, the heterozygote group (CT genotype) had significantly better treatment response than the homozygote group (CC + TT genotypes), especially in the somatic-anxiety subcategory and the total score of HAM-D. These findings imply that a 5-HT6 receptor polymorphism (C267T) is associated with treatment response in MDD.

Adult↗

PubMed2004

A double blind study showing that two weeks of daily repetitive TMS over the left or right temporoparietal cortex reduces symptoms in patients with schizophrenia who are having treatment-refractory auditory hallucinations.

The aim of this study was to evaluate the effect of repetitive transcranial magnetic stimulation (rTMS) on the left and right temporoparietal cortex compared with sham stimulation in schizophrenic patients with treatment-refractory auditory hallucinations (AH). Thirty-nine patients with schizophrenia with treatment-refractory AH were allocated randomly to one of three groups: daily left, right, and sham rTMS groups. rTMS was applied to the TP3 or 4 regions with the aid of the electroencephalography 10-20 international system at 1 Hz for 20 min per day for 10 treatment days. Symptoms were evaluated using the Auditory Hallucination Rating Scale (AHRS), the Positive and Negative Symptoms Scale (PANSS), the Clinical Global Impression--Severity (CGI-S), and Clinical Global Impression--Improvement (CGI-I) scale. For the time effect (within-subject comparison), there were significant changes in the frequency of AHs, positive symptoms of PANSS, and CGI-I. A between-group comparison revealed significant differences in the positive symptoms of PANSS, and CGI-I scores. Post hoc analysis revealed that both the right- and left-side rTMS treatment groups exhibited better CGI-I scores compared to the sham-stimulated group. This study suggests that 10 days of low-frequency rTMS applied daily for 20 min to either temporoparietal cortex significantly reduces the symptoms in patients with schizophrenia who are having refractory AH, but the left sided rTMS is not superior to right or sham rTMS.

Adolescent↗

PubMed2004

Association between norepinephrine transporter gene polymorphism and major depression.

Noradrenergic and serotonergic abnormalities have long been implicated in patients with major depression. The novel selective norepinephrine reuptake inhibitor reboxetine has been shown to be at least as effective as imipramine, desipramine and fluoxetine in the treatment of major depression. It is suggested that the dysfunction of the norepinephrine transporter (NET) may be related to major depression. Although the transcriptional activity related to the NET gene expression is little known, it may be a good candidate gene for major depression. Therefore, we investigated whether the T-182C polymorphism of the NET gene is associated with major depression in a Korean sample of 112 major depression patients compared with 136 healthy controls. We found a significantly lower frequency in TT genotype in patients with major depression than in normal controls when the genotypes of T-182C polymorphism were classified into two groups: TT group versus TC + CC group (p = 0.019). This result suggests that the T-182C polymorphism in the NET gene might be associated with major depression.

Adult↗

PubMed2004

Detection rates of bacteria in chronic otitis media with effusion in children.

This study was performed to investigate polymerase chain reaction-based detection of bacterial DNA in middle ear fluid and assess the correlation between the PCR-positive rate with several factors associated with middle ear effusion. The purpose was to gain a further understanding of bacterial infection as a major cause of otitis media with effusion. Of the 278 specimens of middle ear fluid, 39 (14%) tested positive by ordinary culture. The overall detection rate of bacterial DNA using the PCR method was 36.7% for middle ear effusion, and bacterial DNA detection rates of Hemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis in the middle ear effusion were 29.1%, 4.7% and 10.8%, respectively. The bacterial DNA detection rate was higher in ears with a history of acute otitis media than those without the history. High detection rates were observed in patients younger than 48 months who have had a higher tendency to present with acute otitis media. We concluded that PCR is a more sensitive method for the detection of bacteria in middle ear effusion than ordinary culture, and acute otitis media is a major contributor to the pathogenesis of otitis media with effusion.

Child↗