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Biomedical subjects

D Y Lee

Publications and source records attributed to D Y Lee.

At least 55 records · Page 3Linked to original sources
PubMed2001

Aortic dissection: percutaneous management with a separating stent-graft--preliminary results.

The authors used a separating stent-graft to treat Stanford type B aortic dissection. The separating stent-graft consists of two stents: a stent-graft and an inner bare stent. The separating stent-graft has three parts: a proximal stent, a graft made of synthetic polyester textile fiber, and a distal stent. A 12-F introducing sheath was used. After the separating stent-graft was placed, false-lumen thrombosis was evident in all six patients during a follow-up period of 206 days. The major advantages of this technique are that a cutdown and blood pressure control are not required.

Adult↗
PubMed2001

Purification of soluble beta-glucan with immune-enhancing activity from the cell wall of yeast.

Beta-glucan, one of the major cell wall components of Saccharomyces cerevisiae, has been found to enhance immune functions, especially by activating macrophages. However, a major obstacle to the clinical application of beta-(1-->3)-glucan is its low solubility in aqueous media. In this study, soluble beta-glucan, free of mannoprotein, was prepared, and its effects on TNF-alpha secretion and phagocytosis by macrophages were evaluated. Beta-glucan was first rendered soluble from the yeast cell wall by alkaline extraction (glucan-p1). The extract contained 2.8% of protein which was subsequently removed by successive DEAE-cellulose and ConA chromatography. Beta-glucan thus prepared was completely free of mannoprotein and was soluble at neutral pH (glucan-p3). The effects of beta-glucan on phagocytosis and TNF-alpha release activity were investigated. While glucan-p1 moderately induced TNF-alpha secretion at 200 microg/ml (550 pg of TNF-alpha/5 x 10(5) cells), glucan-p3 markedly stimulated macrophages at 200 microg/ml (2,860 pg of TNF-alpha/5 x 10(5) cells). Furthermore, glucan-p3 stimulated phagocytosis about 20% more than glucan-p1 did. In conclusion, we purified water-soluble beta-glucan which was completely devoid of mannoprotein and effectively stimulated the macrophage function, enabling it to be used as an intravenous injection for sepsis.

Adjuvants, Immunologic↗
PubMed2001

An ischemic skin lesion after chemoembolization of the right internal mammary artery in a patient with hepatocellular carcinoma.

A huge nodular hepatocellular carcinoma located at the anterior superior portion of the left lobe in a patient with hepatocellular carcinoma was treated with transcatheter arterial chemoembolization through the left hepatic artery. Three months later, however, there was a re-elevation of the serum alpha-fetoprotein level and evidence of a marginal recurrence at the left side of the previously embolized tumor was noted on the postembolization computed tomographic scan. Although the hepatic artery was intact in the second hepatic arteriography, we found that the right internal mammary artery was feeding the recurred hepatocellular carcinoma. This internal mammary artery was successfully treated with Lipiodol-transcatheter arterial chemoembolization. However, an ischemic lesion occurred in the skin of the anterior chest and abdominal wall several days after internal mammary artery embolization. We report here a very rare case of ischemic skin lesion on the anterior chest and abdominal wall following transcatheter arterial chemoembolization of the right internal mammary artery. This internal mammary artery was embolized because it had developed a collateral tumor feeding vessel following the initial chemoembolization of a hepatocellular carcinoma.

Carcinoma, Hepatocellular↗
PubMed2001

The effect of 2,5,2',5'-tetrachlorobiphenyl on growth and death of the cyanobacterium Anabaena flos-aquae.

The effect of 2,5,2',5'-tetrachlorobiphenyl (TcBP) on cell death was investigated in the cyanobacterium Anabaena flos-aquae (Lyngb.) Bréb grown in a P-limited, semicontinuous culture under N2-fixing conditions during a 17-d period. The TcBP was supplied daily to yield final concentrations of 1, 10, and 100 ppb (or ng/ml). At 1 and 10 ppb, the population size of live cells (sum of live vegetative cells and live heterocysts) was not different from that of the TcBP-free controls (p > 0.1, t test) and remained constant both in its absolute value (9.6 X 10(5) cells/ml) and as a percentage of the total population (98.6%). However, at 100 ppb, the population size of live cells declined significantly after the 11th day (8.2 x 10(5) cells/ml, or 96.6% of total population; p < 0.01, t test). The decrease in viable cells was mostly found in vegetative cells. Bioconcentration factor in the cell ([pg TcBP/g dry wt cells]/[pg TcBP/ml]) was 1.23 x 10(5).

Anabaena↗
PubMed2001

Using seafood waste as sludge conditioners.

In this study, three kinds of seafood wastes (shrimp shell particles, oyster shell particles, and internal bone particles of squid) were added to dewatered sludge preconditioned with chemical conditioner (alum or ferric chloride). The specific resistance of sludge dewatering was calculated to evaluate the effectiveness of sludge dewatering. The result showed that adding chemical conditioners alone caused noticeable pH decrease and resulted in a conditioned sludge with poor filterability. The addition of oyster shell or internal bone of squid to chemically preconditioned sludge efficiently improved sludge dewatering. This result was possibly due to both the availability of alkaline and the function as skeleton builder provided by these two waste solids. Particle sizes (0.59-2.0 mm) of oyster shell and internal bone of squid were found to have insignificant effect on sludge dewatering.

Conservation of Natural Resources↗
PubMed2000

Vascular endothelial growth factor KDR receptor signaling potentiates tumor necrosis factor-induced tissue factor expression in endothelial cells.

Vascular endothelial growth factor (VEGF) and tumor necrosis factor-alpha (TNF-alpha) have been shown to synergistically increase tissue factor (TF) expression in endothelial cells; however, the role of the VEGF receptors (KDR, Flt-1, and neuropilin) in this process is unclear. Here we report that VEGF binding to the KDR receptor is necessary and sufficient for the potentiation of TNF-induced TF expression in human umbilical vein endothelial cells. TF expression was evaluated by Western blot analysis and fluorescence-activated cell sorting. In the absence of TNF-alpha, wild-type VEGF- or KDR receptor-selective variants induced an approximate 7-fold increase in total TF expression. Treatment with TNF alone produced an approximate 110-fold increase in total TF expression, whereas coincubation of TNF-alpha with wild-type VEGF- or KDR-selective variants resulted in an approximate 250-fold increase in TF expression. VEGF lacking the heparin binding domain was also able to potentiate TF expression, indicating that heparin-sulfate proteoglycan or neuropilin binding is not required for TF up-regulation. Neither placental growth factor nor an Flt-1-selective variant was capable of inducing TF expression in the presence or absence of TNF. Inhibition of protein-tyrosine kinase or protein kinase C activity significantly blocked the TNF/VEGF potentiation of TF up-regulation, whereas phorbol 12-myristate 13-acetate, a protein kinase C activator, increased TF expression. These data demonstrate that KDR receptor signaling governs both VEGF-induced TF expression and the potentiation of TNF-induced up-regulation of TF.

Cells, Cultured↗
PubMed2000

Local radiotherapy for unresectable hepatocellular carcinoma patients who failed with transcatheter arterial chemoembolization.

PURPOSE: The purpose of this study was to investigate the efficacy of local radiotherapy (RT) as a salvage treatment for unresectable hepatocellular carcinoma (HCC) patients who failed with transcatheter arterial chemoembolization (TACE). METHODS AND MATERIALS: Patients with unresectable HCC who had been treated with and eventually failed with TACE were eligible. The judgment of TACE failure was based on incomplete tumor filling of lipiodol-adriamycin mixture on either angiography or computed tomography (CT) scan. From January 1993 to December 1997, 27 patients were entered into this study. They had UICC Stage III (17) or IVA (10) disease, with a mean tumor size of 7.2 +/- 2.9 cm. Local RT was done, with a mean tumor dose of 51.8 +/- 7.9 Gy, in daily 1.8-Gy fractions using a 10- or 6-MV linear accelerator. Survival was calculated from both the diagnosis and the start of RT using the Kaplan-Meier method. RESULTS: An objective response was observed in 16 of 24 patients (66.7%) including 1 CR. Intrahepatic metastasis was noted outside the RT field in 10 patients (37.0%). Extrahepatic distant metastasis occurred in 4 patients. Survival rates at 1, 2, and 3 years were 85. 2%, 58.1%, and 33.2%, respectively, from the diagnosis and 55.9%, 35. 7%, and 21.4%, respectively, from the start of RT. The median survivals were 26 months from the diagnosis and 14 months from the start of RT. Acute toxicity involved alteration in liver function test (13 patients) and thrombocytopenia (2 patients). Subacute and chronic toxicity involved gastroduodenal ulcer (3 patients) and duodenitis (2 patients). There was no treatment-related death. CONCLUSION: In unresectable HCC patients who failed with TACE, local RT induced a substantial tumor response of 66.7%, with a 3-year survival rate of 21.4% and a median survival time of 14 months. Toxicity was significant but manageable. Although we do not know if there is survival benefit through this treatment, local RT in these patients seems to be valuable as a salvage for TACE-failed HCC.

Adult↗
PubMed2000

A thioredoxin from the hyperthermophilic archaeon Methanococcus jannaschii has a glutaredoxin-like fold but thioredoxin-like activities.

A thioredoxin homologue (Mj0307) from the hyperthermophilic archaeon Methanococcus jannaschii (MjTRX) was cloned, produced in E. coli, and compared to the thioredoxin from E. coli (ETRX). The secondary structure profile of MjTRX obtained by NMR spectroscopy shows that it has four beta-sheets and three alpha-helices arranged in betaalphabetaalphabetabetaalpha, similar to that of glutaredoxin. However, MjTRX supports the growth of T7 bacteriophage in E. coli and is weakly reduced by the thioredoxin reductase from E. coli, indicating that MjTRX is functionally closer to a thioredoxin than a glutaredoxin. MjTRX has higher specific insulin reductase activity than ETRX and retained its full activity over 4 days at 95 degrees C, whereas ETRX lost its activity in 150 min. The standard state redox potential of MjTRX is about -277 mV, which is the lowest value thus far known among redox potentials of the thioredoxin superfamily. This indicates that the lower redox potential is necessary in keeping catalytic disulfide bonds reduced in the cytoplasm and in coping with oxidative stress in an anaerobic hyperthermophile.

Amino Acid Sequence↗
PubMed2000

No association between alpha-1-antichymotrypsin polymorphism and Alzheimer's disease in Koreans.

To examine the possible involvement of the alpha-1-antichymotrypsin gene (ACT) polymorphism in the manifestation of Alzheimer's disease (AD), we analyzed genotypes of the ACT and apolipoprotein E gene (APOE) among 110 Korean patients with probable AD and 209 nondemented controls. No significant difference was obtained in genotypic (chi(2)=1.98, df=2, P>0.1) and allelic frequencies (chi(2)=1.61, df=1, P>0.1) of ACT between the AD and control groups. No overexpression of the ACT A/A genotype and ACT A allele was found when we analyzed the late-onset AD patients and the early-onset AD patients, separately. Then we stratified the ACT genotypes based on the presence or absence of the APOE epsilon4 allele to evaluate the possible interaction between them. In the APOE epsilon4-negative subjects, although the ACT A allele tended to be overexpressed in the AD group, the differences in the frequencies of the ACT A allele (chi(2)=2.79, df=1, P>0.1) and ACT A/A genotype (chi(2)=0.16, df=1, P>0.1) were not statistically significant. No significant overrepresentations of the ACT A allele (chi(2)=0.02, df=1, P>0.1) and ACT A/A genotype (chi(2)=0.17, df=1, P>0.1) were found in the APOE epsilon4-positive subjects, either. In addition, the status of the ACT genotype did not influence the age-at-onset of AD (F=0.03, df=2, P>0.1). Therefore, the ACT polymorphism does not contribute to the development of AD independently or interactively with the APOE epsilon4 allele in Koreans.

Age of Onset↗
PubMed2000

Regulation of proliferation of the fetal myocardium.

Growth of the myocardium involves the completion of a fixed number of rounds of cell division during the embryonic and fetal stages followed by entry into a postmitotic state and hypertrophy of the postmitotic cardiomyocytes during the later stages of heart growth. It has been suggested that at the time of its determination in the early embryo, the embryonic myocardium is programmed for a fixed and limited number of cell divisions, after which the transition to the postmitotic state occurs autonomously. The proliferative response of cultured myocardium of the fetal chick was explored in four culture settings: monolayer cell culture, collagen lattice culture, organ culture of reaggregated cardiomyocyte tissue (cardiomyocyte spheroid culture), and organ culture of pieces of the ventricle wall. Several growth factors were identified by their ability to stimulate DNA synthesis in cardiomyocytes, identified by the incorporation of 5-bromodeoxyuridine (BrdU). The serine proteases thrombin and trypsin, fibroblast growth factor-2 (FGF-2), transforming growth factor-alpha (TGF-alpha), and insulin-like growth factor-II (IGF-II) all show growth factor activity but only for cardiomyocytes cultured in three-dimensional myocardial tissue, and not for cardiomyocytes maintained in monolayer cell culture. Thus, during its proliferation phase, the growth of the fetal myocardium is not controlled solely by internal, cell-autonomous programs, but is subject to external regulation by a family of peptide growth factors. The unconventional setting of three-dimensional culture of the myocardium is required to demonstrate its responsiveness to growth factor challenge.

Animals↗
PubMed2000

A comparison of mechanical properties of all-ceramic alumina dental crowns prepared from aqueous- and non-aqueous-based tape casting.

Alumina-glass dental composites were prepared by aqueous- and non-aqueous-based tape casting and sintering at 1120 degrees C, followed by glass infiltration at 1100 degrees C. Flexural strength and fracture toughness of the composites were investigated in terms of influence of tape constituents, namely, alumina powder, binder, and plasticizer on the mechanical properties. For the alumina-glass composites prepared from the aqueous-based tapes, both strength and toughness increased with increasing alumina fraction ratio in tape constituents including organic substances, a/a+o, and binder content ratio in binder/binder + plasticizer mixture, b/b+p. For the composites prepared from the non-aqueous-based tapes, on the other hand, both strength and toughness increased with increasing the a/a+o ratio but decreased with increasing the b/b+p ratio. These observations were consistent with influence of the constituents on mean alumina particle distance in tapes, suggesting that high strength of the glass infiltrated alumina composites is related to toughening by crack bowing. The optimized strength of the aqueous and nonaqueous tape cast composites was 559 and 508 MPa, and the fracture toughness was 3.3 and 3.1 MPam(1/2), respectively.

Aluminum Oxide↗
PubMed2000

Mechanical properties, phase stability, and biocompatibility of (Y, Nb)-TZP/Al(2)O(3) composite abutments for dental implant.

ZrO(2)/Al(2)O(3) composites were prepared by mixing a tetragonal ZrO(2), stabilized by 5.31 mol% Y(2)O(3) and 4.45 mol% Nb(2)O(5), and various amounts of Al(2)O(3). Influence of the amount of Al(2)O(3) on strength and toughness and tetragonal phase stability in the composites under autoclave conditions was investigated. In addition, in vitro and in vivo biocompatibility of the composites was examined. The composite, prepared with addition of 20 vol% Al(2)O(3), exhibited the highest strength of 700 MPa and toughness of 8.1 MPa. m(1/2) and showed no hydrothermal degradation while aging in an autoclave. The biocompatibility of the composite exhibited no cytotoxicity and no significant adverse soft-tissue response for up to 3 months implant period in guinea pigs.

Aluminum Oxide↗
PubMed2000

No association between presenilin 1 (PS1) intronic polymorphism and sporadic Alzheimer's disease in Koreans.

To investigate the possible involvement of an intronic polymorphism in the presenilin 1 (PS1) gene and its interactions with the aplolipoprotein E (APOE) or alpha-1 antichymotrypsin (ACT) polymorphisms in the manifestation of AD, we analyzed the PS1, APOE and ACT genotypes of 100 sporadic AD patients and 199 normal elderly controls in Koreans. The genotypic (chi2= 0.92, df = 2, P > 0.1) and allelic (chi2 = 0.01, df = 1, P > 0.1) frequencies of the PS1 polymorphism in the late- and early-onset sporadic AD patients did not differ from those in the controls. And the occurrence of the APOE epsilon4 allele and ACT A allele did not influence the distribution of the PS1 intronic polymorphism. The PS1 intronic polymorphism didn't influence the age-at-onset of AD (F = 0.02, df = 2, P > 0.1). In conclusion, the PS1 intronic polymorphism did not modify the risk for sporadic AD, neither independently nor synergistically with the APOE epsilon4 allele or ACT A allele, in Koreans.

Age of Onset↗
PubMed2000

Needle thoracic sympathectomy for essential hyperhidrosis: intermediate-term follow-up.

BACKGROUND: Essential hyperhidrosis is a condition with excessive sweating localized to certain part of the body. A definitive cure can be obtained by upper thoracic sympathectomy. METHOD: Between June and October 1997, 117 patients with essential hyperhidrosis underwent needle thoracoscopic sympathectomy. Of the 94 patients, 42 were men and 52 women. Their ages ranged from 14 to 63 years, with a mean age of 23 years. RESULTS: There were no mortality or life-threatening complications. Symptomatic improvement was found in 95.7%. Compensatory hyperhidrosis was found in 71.2% of the patients, but in these compensatory hyperhidrosis were mostly tolerable. CONCLUSIONS: This therapeutic procedure is minimally invasive and very effective. Further development of the new device and surgical technique are expected to follow.

Adolescent↗
PubMed2000

Modulation of neuroendocrinological function by psychosomatic training: acute effect of ChunDoSunBup Qi-training on growth hormone, insulin-like growth factor (IGF)-I, and insulin-like growth factor binding protein (IGFBP)-3 in men.

The neuroendocrine system is regarded as the major link between the psychological state and the immune system in man. The present study was undertaken to examine the acute effect of ChunDoSunBup Qi-training, a traditional psychosomatic training, on the plasma level of growth hormone (GH), insulin-like growth factor (IGF)-I and insulin like growth factor binding protein (IGFBP)-3 in young men. To characterize the plasma level of hormones and the pattern of IGFBP-3 at pre- (-10 min), mid-time (40 min), and immediately after (post-time, +10 min) Qi-training, radioimmunoassay (RIA) and western ligand blot (WLB) analysis were used. The plasma level of GH at the mid-time was significantly increased (P<0.05) compared to the level at pre-time of Qi-training. The plasma level of IGF-I was also increased at mid-time (P<0.05) and immediately after Qi-training. There was a significant correlation between the levels of GH and IGF-I immediately after Qi-training (r=0.69, P<0.01). In this study, the change of IGFBP-3 among the several IGFBPs was determined. There was a relative shift in IGFBP-3 for the 43-kDa fraction during mid-time of Qi-training (P<0.05). These results suggest that Qi-training influences the growth hormone, IGF-I and IGFBP-3 status via brain-target organ axis in men.

Adult↗
PubMed2000

A new skin equivalent model: dermal substrate that combines de-epidermized dermis with fibroblast-populated collagen matrix.

Epidermis reconstructed on de-epidermized dermis (RE-DED) and on fibroblast-populated collagen matrix (Living Skin Equivalent) showed a histologic resemblance to native epidermis. However, some abnormalities have been found including different expression pattern of differentiation markers from native epidermis. In this study, to reconstruct an epidermis model resembling native epidermis more closely than previous skin equivalents, de-epidermized dermis (DED) was raised on fibroblast-populated collagen matrix and keratinocytes were cultured on top of the DED at the air-liquid interface. The new skin equivalent like RE-DED showed a similar morphology to that of native epidermis. Immunohistochemical studies revealed that differentiation markers such as involucrin, loricrin and filaggrin but not keratin 1 expressed similar pattern characteristics to native epidermis compared with those of RE-DED. In addition, the new model showed some fibroblasts in the DED as a result of migration from the fibroblast-populated collagen matrix, mimicking a living dermis in vivo. These results indicate that the new model seems to be a better skin equivalent model than previous models. Also, they provide additional evidence that the presence of fibroblasts improves epidermal differentiation.

Cells, Cultured↗
PubMed2000

Dysembryoplastic neuroepithelial tumor: radiological findings (including PET, SPECT, and MRS) and surgical strategy.

In order to elucidate the radiological features of dysembryoplastic neuroepithelial tumor (DNT), and to clarify the optimal surgical strategy for this tumor, the authors retrospectively analyzed 20 cases of DNT treated at our institution. Magnetic resonance (MR) imaging (all cases), 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) (eight cases), ictal/interictal Tc99m-HMPAO single photon emission computed tomography (SPECT) (seven and five cases respectively) and proton magnetic resonance spectroscopy (1H MRS) (one case) were performed preoperatively. Invasive monitoring/intraoperative electrocorticography (ECoG) was performed in four cases in order to determine the epileptogenic zone. A well-demarcated lobulating tumor located in the cortical with/without subcortical area was the typical MR finding. 18F-FDG PET showed glucose hypometabolism in all cases. Ictal Tc99m-HMPAO SPECT showed hyperperfusion of the lesion in three cases and interictal Tc99m-HMPAO SPECT showed hypoperfusion of the lesion in one case. 1H MRS showed nonspecific findings. Gross total resection was performed in all cases. Histologically, associated cortical dysplasia was found in 11 cases. The mean duration of follow-up after surgery was 37.9 months, and the overall seizure free rate was 90%. Follow-up MR imaging was performed in 14 cases (mean duration of follow-up: 21.6 months) and showed no recurrence of tumor in any of these cases. Invasive monitoring/intraoperative ECoG and the presence of cortical dysplasia showed no significant relationship with seizure control rate (p = 1.25 and p = 1.62 respectively).

Adolescent↗