Biomedical subjects

H J Chun

Publications and source records attributed to H J Chun.

At least 37 records · Page 2Linked to original sources

PubMed1999

Involvement of specific calmodulin isoforms in salicylic acid-independent activation of plant disease resistance responses.

The Ca2+ signal is essential for the activation of plant defense responses, but downstream components of the signaling pathway are still poorly defined. Here we demonstrate that specific calmodulin (CaM) isoforms are activated by infection or pathogen-derived elicitors and participate in Ca2+-mediated induction of plant disease resistance responses. Soybean CaM (SCaM)-4 and SCaM-5 genes, which encode for divergent CaM isoforms, were induced within 30 min by a fungal elicitor or pathogen, whereas other SCaM genes encoding highly conserved CaM isoforms did not show such response. This pathogen-triggered induction of these genes specifically depended on the increase of intracellular Ca2+ level. Constitutive expression of SCaM-4 and SCaM-5 in transgenic tobacco plants triggered spontaneous induction of lesions and induces an array of systemic acquired resistance (SAR)-associated genes. Surprisingly, these transgenic plants have normal levels of endogenous salicylic acid (SA). Furthermore, coexpression of nahG gene did not block the induction of SAR-associated genes in these transgenic plants, indicating that SA is not involved in the SAR gene induction mediated by SCaM-4 or SCaM-5. The transgenic plants exhibit enhanced resistance to a wide spectrum of virulent and avirulent pathogens, including bacteria, fungi, and virus. These results suggest that specific CaM isoforms are components of a SA-independent signal transduction chain leading to disease resistance.

Calcium↗

PubMed1999

Dendritic cells/chimerism/alleviation of chronic allograft rejection.

Chronic rejection (CR) is the major obstacle of long-term successful organ transplantation. Using a recently developed rat model of CR, we found that heart allografts susceptible to development of CR showed an early (< 10 days) dramatic disappearance of donor MHC class II+ cells, including ED2+ tissue macrophages, and an influx of recipient ED1+ macrophages intermixed with small numbers of recipient ED2+ and OX62+ cells. In contrast, donor MHC class II+ cells persisted in allografts resistant to CR with a small influx of recipient macrophages. MHC class II+ cells function as potent modulators of the immune system and may mediate both stimulatory and tolerogenic immune reactions after transplantation. Persistence of donor MHC class II+ antigen-presenting cells (APC) in CR-free graft acceptance suggests that transplantation tolerance is an active immune response requiring antigen presentation to the recipient immune system in the proper context by dendritic cells and other APC.

Animals↗

PubMed1999

Association of pseudoachalasia with advancing cancer of the gastric cardia.

BACKGROUND: Pseudoachalasia is attributable to malignant tumors of the gastric cardia in more than 50% of cases. Study of the progression of esophageal manometric abnormalities with increasing tumorous involvement of the esophagogastric junction may improve our understanding of the pathophysiologic characteristics of pseudoachalasia. METHODS: During a 2-year period, esophageal manometric characteristics were evaluated for 17 of 21 consecutive patients with cancer of the gastric cardia. Manometry was not possible in the other four. Manometric parameters assessed included lower esophageal sphincter pressure, percentage lower esophageal sphincter relaxation, and percentage failed peristalsis. The extent of malignant involvement of the esophagogastric junction was graded as none, less than 50% of the circumference, or 50% or more of the circumference, assessed from surgical specimens in 13 cases and endoscopy in 4 cases. RESULTS: Pseudoachalasia was diagnosed in 3 cases, all with 50% or greater circumferential involvement of the esophagogastric junction. The first manometric indication of evolving pseudoachalasia was impaired lower esophageal sphincter relaxation; loss of peristaltic function was a secondary consequence. CONCLUSIONS: These findings suggest that the primary mechanism of pseudoachalasia with gastric cardia cancer is malignant stenosis of the esophagogastric junction.

Adult↗

PubMed1999

Effect of resection velocity and suction ring on corneal flap formation in laser in situ keratomileusis.

PURPOSE: To determine the effects of microkeratome-cutting velocities and the suction ring on corneal flap creation. SETTING: Department of Ophthalmology, College of Medicine, The Catholic University of Korea, Seoul, Korea. METHODS: Procedures were performed under clinical settings in 65 pig eyes. Keratometric diopters (D) were measured before and after application of the suction ring. Corneal thickness was measured before and after resection cutting, and the difference was taken as flap thickness. The microkeratome was initially set at a resection thickness of 160 microns. The blade oscillation (turbine velocity) was set at 30, 35, and 42 psi. The translational velocity was arbitrarily divided into high (1 to 2 seconds), moderate (3 to 5 seconds), and low (6 seconds or more). Data were analyzed by varying the velocities consecutively. Photographs of the cut surface were acquired by scanning electron microscopy to evaluate resection morphology by comparison. RESULTS: Mean refractive powers were 39.94 D +/- 0.66 (SD) and 39.69 +/- 0.98 D before and after application of the suction ring, respectively; however, no significant difference was observed (P = .216). Lower surgeon translational velocity resulted in a significantly thicker corneal flap in 8 of the 9 paired comparisons (P < .05). Higher turbine velocity resulted in a significantly thicker corneal flap in 7 of the 9 paired comparisons (P < .05). The cut surface was smoother at higher turbine and lower translational velocity. The initial cut margin was steeper at higher translational velocity. CONCLUSIONS: The increase in intraocular pressure induced by the suction ring had no significant effect on keratometric power. At higher turbine and lower translational velocities, the corneal flap was thicker and the cut surface smoother. Higher translational velocities made the initial cut margin steeper.

Animals↗

PubMed1999

Endoscopic removal of submucous tumours.

Although gastrointestinal submucous tumours are increasingly being discovered with the development of endoscopic examination techniques, the reliable diagnosis of these lesions remains difficult at present. Before endoscopy became available, the treatment strategy for gastrointestinal submucous tumours was either surgery or observation. With the rapid evolution of therapeutic endoscopy, the endoscopic removal of various tumours in the gastrointestinal tract has been described, but the resection of submucous tumours is still reported only infrequently. Endoscopic removal of submucous tumours of the gastrointestinal tract has yet to become widespread, and this technique has not been fully evaluated. Not all patients need the treatment; however, endoscopic submucous tumour removal may be the treatment of choice for certain patient subgroups. This article reviews recent literature regarding the endoscopic removal of gastrointestinal submucous tumours and discusses the possibility of removing submucous tumours using endoscopic resection.

Adenocarcinoma, Mucinous↗

PubMed1999

Biliary papillary hyperplasia with clonorchiasis resembling cholangiocarcinoma.

Infection by the liver fluke Clonorchis sinensis is very common in the Far East. It causes low grade inflammatory changes and proliferation in the biliary tree. Initially there is desquamation of the biliary epithelium, followed by hyperplasia and adenomatous proliferation. Cholangiocarcinomas are potential long term complications. We present a case of biliary papillary hyperplasia with clonorchiasis resembling cholangiocarcinoma in a 69-yr-old Korean man. Early recognition of biliary hyperplasia and treatment of Clonorchis sinensis is important to prevent development of cholangiocarcinoma, especially in the Far East.

Aged↗

PubMed1999

Metastasis-induced acute pancreatitis in a patient with small cell carcinoma of the lung.

Acute pancreatitis in cancer patients can be secondary to the malignant process itself or a complication of antineoplastic agent administration. However, acute pancreatitis caused by metastatic carcinoma of the pancreas is an uncommon condition with a poor prognosis. We report a case of a 63-year-old man with small cell carcinoma of the lung, who developed acute pancreatitis lately. Thirteen months earlier, he developed small cell carcinoma of the lung and received 6 cycles of chemotherapy. Abdominal CT scan showed swelling of the pancreas with multiple masses. The patient was managed conservatively and pancreatitis subsided. This case indicates that metastasis induced acute pancreatitis can be a manifestation of lung cancer, especially in small cell carcinoma.

Carcinoma, Small Cell↗

PubMed1999

Epirubicin, cisplatin, oral UFT, and calcium folinate in advanced gastric carcinoma.

UFT (uracil and tegafur in a 4:1 molar ratio) plus calcium folinate treatment has favorable activity and tolerable toxicity in patients with advanced gastric carcinoma. High response rates have been reported in patients with advanced gastric carcinoma receiving a schedule of epirubicin, cisplatin (Platinol), and protracted infusion of 5-fluorouracil (5-FU). Replacing the inconvenient infusion pump and intravenous catheter needed for protracted infusion of 5-FU, we administered oral UFT plus calcium folinate (Orzel) to 37 patients (median age, 55 years; median World Health Organization [WHO] performance status of 1) with locally advanced or metastatic gastric carcinoma. Epirubicin 50 mg/m2 and cisplatin 60 mg/m2 were administered by intravenous injection on day 1; UFT 360 mg/m2/day po was administered in conjunction with oral calcium folinate 25 mg/m2/day in divided daily doses for 21 days, followed by a 7-day rest period. Courses were repeated every 4 weeks. Among 37 evaluable patients who received a median of four courses of treatment (range, 2 to 10), two achieved a complete response and 18 a partial response, for an overall response rate of 54% (95% confidence interval, 39% to 70%). Stable disease was reported in 12 patients (32.4%) and disease progression in another five (13.5%). The median duration of survival was 10 months (range, 2 to 15+). The main toxicities were nausea/vomiting, leukopenia, diarrhea, and oral mucositis. WHO grade 3 or 4 toxicity included leukopenia in 14 patients (37.8%), nausea/vomiting in 11 (29.7%), oral mucositis in five (13.5%), and diarrhea in four (10.8%). Epirubicin, cisplatin, and oral UFT plus calcium folinate, a convenient outpatient regimen, has significant activity and tolerable toxicities in patients with gastric carcinoma.

Adenocarcinoma↗

PubMed1999

Noninvasive graft flow and patency assessment following minimally invasive direct coronary artery bypass (MIDCAB) grafting.

OBJECTIVE: Assessment of graft patency following minimally invasive direct coronary artery bypass (MIDCAB) surgery is essential in order to determine the efficacy of this technique. This study was conducted to evaluate the role of intraoperative and postoperative noninvasive flow and velocity measurements to follow and predict graft performance. METHODS: Between April 1996 and July 1997, 130 patients had 133 grafts placed using MIDCAB techniques. Intraoperative transit-time ultrasound was used to assess graft patency and flow prior to wound closure. Also, serial transcutaneous doppler examinations were performed to evaluate graft patency on the first postoperative day, at two weeks, and at three months. Peak values for systolic and diastolic waveforms were measured for both flow and velocity, and the diastolic-to-systolic ratio was calculated at each time interval. Recatheterization was performed selectively for inadequate ultrasound flow or doppler velocity, or for patient symptoms. RESULTS: Seven (5.3 %) grafts developed stenosis or occlusion. When compared to normal grafts, mean intraoperative flows, flow ratios, and velocity ratios were lower. Mean postoperative diastolic peak velocity (DPV) to systolic peak velocity (SPV) ratio remained stable over time for normal grafts; however, grafts with stenosis or occlusion demonstrated a diminished DPV/SPV ratio. CONCLUSIONS: Intraoperative transit-time ultrasound and outpatient transcutaneous doppler examinations did not reach a predictive value for graft stenosis or occlusion following MIDCAB surgery in this series of patients. However, these data demonstrate trends that may help identify patients at an increased risk for unfavorable events, guiding the use of postoperative recatheterization in such patients.

Aged↗

PubMed1998

Two hevein homologs isolated from the seed of Pharbitis nil L. exhibit potent antifungal activity.

Two antifungal peptides (Pn-AMP1 and Pn-AMP2) have been purified to homogeneity from seeds of Pharbitis nil. The amino acid sequences of Pn-AMP1 (41 amino acid0 residues) and Pn-AMP2 (40 amino acid residues) were identical except that Pn-AMP1 has an additional serine residue at the carboxyl-terminus. The molecular masses of Pn-AMP1 and Pn-AMP2 were confirmed as 4299.7 and 4213.2 Da, respectively. Both the Pn-AMPs were highly basic (pI 12.02) and had characteristics of cysteine/glycine rich chitin-binding domain. Pn-AMPs exhibited potent antifungal activity against both chitin-containing and non-chitin-containing fungi in the cell wall. Concentrations required for 50% inhibition of fungal growth were ranged from 3 to 26 micrograms/ml for Pn-AMP1 and from 0.6 to 75 micrograms/ml for Pn-AMP2. The Pn-AMPs penetrated very rapidly into fungal hyphae and localized at septum and hyphal tips of fungi, which caused burst of hyphal tips. Burst of hyphae resulted in disruption of the fungal membrane and leakage of the cytoplasmic materials. To our knowledge, Pn-AMPs are the first hevein-like proteins that show similar fungicidal effects as thionins do.

Amino Acid Sequence↗

PubMed1998

Cytogenetic and fluorescence in situ hybridization analyses of hematologic malignancies in Korea.

Cytogenetic analysis was performed in 86 cases of hematologic malignancy, using conventional cytogenetic analysis and fluorescence in situ hybridization (FISH) analysis at two university hospitals in Korea between 1993 and 1995. In addition to well-known anomalies, some unusual abnormalities were found, such as t(17;22), trisomy 9 combined with t(14;17), (2;7) and Philadelphia chromosome in CML; t(1;12), t(11;22), t(9;17), and t(12;21) in AML; trisomy 11 in MDS; t(2;9) and complex t(8;8;13;14) in ALL. The results of FISH analysis in interphase nuclei using a translocation probe for CML and APL showed more than 85% positive cells in CML, and 75% positive cells in APL.

Adult↗

PubMed1998

Chronic ethanol consumption affects glutathione status in rat liver.

There is no consensus yet on the role of oxidative stress in the nutritional outcome of chronic ethanol feeding and the status of cellular antioxidative defense systems against ethanol toxicity. In this study, chronic alcohol consumption in humans was reproduced in Sprague-Dawley rats to investigate the effect of ethanol ingestion on the regulation of oxidative stress in liver with a special focus on glutathione. Adult male rats were given 36% of total energy as alcohol in the Lieber-DeCarli liquid diet for 6 wk. The control group was pair-fed the diet containing isocaloric dextrin-maltose instead of ethanol. Chronic ethanol ingestion enhanced expression of cytochrome P450 II E1 in the liver, but did not significantly alter either the level of hepatic thiobarbituric acid reactive substances or the carbonyl group content of proteins. The hepatic concentrations of total and reduced glutathione and the activities of catalase, glutathione reductase and glutathione S-transferase were significantly higher in the ethanol group than in the control group. The activities of glutathione peroxidase and glucose-6-phosphate dehydrogenase were significantly lower in the ethanol group than in controls. Chronic ethanol consumption by well-nourished rats for 6 wk increased enzyme activities related to the recycling and utilization of glutathione in the liver. Such an enhancement in the activities of the hepatic antioxidative defense system may be one of the protective mechanisms of the body against oxidative tissue damage caused by ethanol-induced free radicals.

Alcohol Drinking↗

PubMed1998

Benign solitary fibrous tumour of the pre-sacral space: MRI findings.

Benign solitary fibrous tumour, a rare mesenchymal tumour of adults, usually arises from the pleura. Only a few cases have been reported in the retroperitoneum and, to our knowledge, there has been no report of its imaging features. We describe the MRI features of benign solitary fibrous tumour arising from the pre-sacral space.

Humans↗

PubMed1998

Effects of levosulpiride in patients with functional dyspepsia accompanied by delayed gastric emptying.

OBJECTIVES: Levosulpiride is the levo-enantiomer of sulpiride, a well-known antiemetic, antidyspeptic and antipsychotic drug. This study was undertaken to investigate the effects of levosulpiride on dyspeptic symptoms and gastric motor function in a group of patients with functional dyspepsia showing delayed gastric emptying. METHOD: Forty two eligible patients were entered into a 3 week, double-blind randomized comparison of 25mg of levosulpiride or placebo t.i.d.. Symptom assessment and gastric scintigraphy following the intake of scrambled egg sandwich, were performed in each patient before and after treatment. RESULTS: The improvement of symptom score in levosulpiride group was higher than the placebo group (p < 0.05). We assessed global efficacy, which was excellent in 1 (6%), good 11 (65%), fair 4 (24%), nil 1 (6%) of those receiving levosulpiride, and fair 9 (60%), nil 5 (33%), poor 1 (6%) of those receiving placebo. Levosulpiride tended to be more effective than placebo in relieving the dyspeptic symptoms especially in the subgroups of dysmotility-like (p < 0.05) and nonspecific (p < 0.05) as compared to other subgroups (p = 0.16). The reduction of gastric emptying time after levosulpiride treatment was more marked than Placebo group (p < 0.05). We found a significant correlation between changes of symptom score and gastric emptying time (r = 0.47, p = 0.01). No serious adverse effects were reported after administration of either levosulpiride or placebo. Only two patients reported mild somnolence during levosulpiride administration. CONCLUSIONS: Levosulpiride is effective and well tolerated in patients with functional dyspepsia accompanied by delayed gastric emptying. Its efficacy may be related to its action on the gastric motor function by improving the delayed gastric emptying.

Adolescent↗

PubMed1997

Endoscopic resection of submucosal tumor of the esophagus: results in 62 patients.

BACKGROUND AND STUDY AIMS: Although most submucosal tumors of the esophagus are benign, reliable exclusion of leiomyosarcoma requires histological analysis. However, this is rarely possible with an endoscopic forceps biopsy. In an attempt to establish the diagnosis, and as an alternative to surgery, we present here our experience with the endoscopic removal of submucosal tumors of the esophagus using two different techniques. PATIENTS AND METHODS: Sixty-two patients (38 men, 24 women, mean age 47) with submucosal tumors of the esophagus were treated endoscopically. If the tumor was less than 2 cm in diameter, polypoid, or showed a round protrusion with at least moderate elevation at endoscopy, a conventional snare polypectomy was performed. If the tumor was larger than 2 cm in diameter or only mildly elevated, the technique of modified endoscopic incisional enucleation was carried out, consisting of complete stripping of the overlying tissue followed by tumor enucleation using an electrocautery snare and a coagulation electrode. RESULTS: Based on these criteria, 36 patients underwent conventional snare polypectomy, and 25 received endoscopic incisional enucleation; complete resection of the tumor was possible in these 61 cases. In one patient, only partial removal was possible, due to firm and wide adhesions to the surrounding tissue. The tumor diameters ranged from 0.6 cm to 7.5 cm, with a mean value of 1.9 cm; 14 tumors measured more than 3 cm. At histopathology, the resected specimens were found to be 56 leiomyomas, four granular cell tumors, one neurogenic tumor, and one cyst. No serious complications such as perforation or massive bleeding occurred, and oozing bleeding, which was encountered in three patients, was easily managed by endoscopic electrocoagulation. During the follow-up period (mean 38.4 months, range 3-107 months) no recurrence was observed in any of the 61 patients who received complete resections. CONCLUSION: This method of endoscopic removal of submucosal tumors of the esophagus appears to be safe and effective in experienced hands. It allows complete histopathological workup, and at the same time complete removal of the tumor. The method can be considered as an alternative to surgery in symptomatic cases.

Adult↗

PubMed1997

Glutathione recycling is attenuated by acute ethanol feeding in rat liver.

The mechanism for ethanol-induced oxidative stress has been disputed because of the controversies on modulation of radical generating and scavenging activities by ethanol. In the present work, we attempted to clarify the acute effect of ethanol on the radical generating system as well as the radical scavenging system. For that purpose, chow-fed rats were given ethanol (5 g/kg) or isocaloric glucose solution by intragastric intubation and placed at 32 degrees C for 6 hr. Acute ethanol administration enhanced the expression of cytochrome P450 II E1(CYP II E1) in the liver and attenuated the activities of hepatic glutathione peroxidase (GPx) and reductase (GR). It also caused a significant increase in the level of hepatic thiobarbituric acid reactive substances (TBARS), an indicator of lipid peroxidation. On the other hand, acute ethanol feeding had no effect on the activities of catalase, xanthine oxidase (XO), glutathione transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH). From this result, it is suggested that acute ethanol administration causes the oxidative tissue damage by CYP II E1-associated radical generation and the decreased radical scavenging function due to the reduced activities of hepatic glutathione recycling system such as GPx and GR.

Alcohol Drinking↗

PubMed1996

NF-AT-Driven interleukin-4 transcription potentiated by NIP45.

The induction of cytokine gene transcription is mediated in part by the nuclear factor of activated T cells (NF-AT). Factors involved in the mechanisms of NF-AT-mediated transcription are not well understood. A nuclear factor that interacted with the Rel homology domain (RHD) of NF-ATp was identified with the use of a two-hybrid interaction trap. Designated NIP45 (NF-AT interacting protein), it has minimal similarity to any known genes. Transcripts encoding this factor were enriched in lymphoid tissues and testes. NIP45 synergized with NF-ATp and the proto-oncogene c-Maf to activate the interleukin-4 (IL-4) cytokine promoter; transient overexpression of NIP45 with NF-ATp and c-maf in B lymphoma cells induced measurable endogenous IL-4 protein production. The identification of NIP45 advances our understanding of gene activation of cytokines, critical mediators of the immune response.

Amino Acid Sequence↗

PubMed1995

A new method of endoscopic variceal ligation-injection sclerotherapy (EVLIS) for gastric varices.

OBJECTIVES: For esophageal varices, endoscopic variceal sclerotherapy and band ligation have been effectively and frequently used, but these methods were not effective for gastric varices. In gastric varices, because of rich networks of feeding vessels and shunts that may exist in many cases, an effective therapeutic level of sclerosant is difficult to be maintained. Accordingly, we propose a new method called "Endoscopic Variceal Ligation-Injection Sclerotherapy (abbreviated EVLIS)" for gastiric varices, with focus on maintenance of the effective therapeutic level of a sclerosant by partially blocking the blood flow of gastric varices using the band ligation method. The study was undertaken prospectively to evaluate the efficacy and safety of EVLIS for the treatment of gastric varices. METHODS: EVLIS was performed in a group of 32 patients with gastric varices. Active bleeding varices were 11 and non-bleeding 21. Five cases were grade A, 12 grade B, and 14 grade C of Child's classification. Nine cases were type 1, 22 type 2, and 1 was type 3 of Hosking-Johnson's classification. RESULTS: The results of EVLIS were excellent, active bleeding of gastric varices in the 11 cases were successfully controlled and all the gastric varices of 32 cases including those bleeding varices were completely eradicated. The bleeding status, the Child's grade and the Hosking-Johnson's class do not appear to correlate in any way with the efficacy of this technique. No perforation or re-bleeding was observed in any of the patients until the mean 10.6 months of the follow-up period. CONCLUSIONS: EVLIS should be considered as an effective and safe treatment for gastric varices.

Adult↗