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Biomedical subjects

K J Cho

Publications and source records attributed to K J Cho.

At least 19 recordsLinked to original sources
PubMed2006

Effective sludge solubilization treatment by simultaneous use of ultrasonic and electrochemical processes.

Sludge disintegration treatment by using simultaneously ultrasonic irradiation and electrolysis was investigated experimentally. A lab-scale diaphragm cell irradiated with ultrasound at a constant oscillating frequency of 20 kHz was used as a reactor. The batch experiments were carried out under different conditions of electric outputs of the ultrasonic generator, electric current for the electrolysis and different initial SS concentrations. A simultaneous treatment in the cathodic compartment without any chemical doses considerably facilitated the sludge solubilization, compared to the sonication alone. An increase in the electric current up to 400 mA under a constant ultrasonic density decreased the specific energy by 55% within the experimental range. The specific energy consumption was also reduced when the initial SS concentration increased. In addition, before carrying out the simultaneous treatment, a brief electrolysis was effective for further reduction of the specific energy and the acceleration of soluble COD generation.

Electrochemistry↗
PubMed2006

Settling characteristics of problem algae in the water treatment process.

The settling velocity or removal rates of problem algae in the water treatment process and their flocculants were measured with settling column (SETCOL) and fluorometric method. Our research who were centred on the algal density and shape affecting the settling. The settling velocities of large algae ranged from 0.1 cm/h to 2.6 cm/h, whereas those of small algae were below 1.0 cm/h. The settlings of algae in the stationary growth phase significantly increased and dead algae corresponded with the declining algae. The extent of deformation, which was expressed as the coefficient of form resistance of the algae had the great influences upon the settling. The most extreme deformed algae were needle-shaped ones like Synedra acus, which was known to be a problem in water treatment processes in Korea. Changes in the settling velocity of algae were correlated with algal volume and morphology rather than cell density.

Eukaryota↗
PubMed2005

On the origin of preferential growth of semiconducting single-walled carbon nanotubes.

A correlation is observed between the diameters (d) of single-walled carbon nanotubes and the percentages of metallic and semiconducting tubes synthesized at 600 degrees C by plasma-assisted chemical vapor deposition. Small tubes (d approximately 1.1 nm) show semiconductor percentages that are much higher than expected for a random chirality distribution. Density functional theory calculations reveal differences in the heat of formation energies for similar-diameter metallic, quasi-metallic, and semiconducting nanotubes. Semiconducting tubes exhibit the lowest energies and the stabilization scales with approximately 1/d(2). This could be a thermodynamic factor in the preferential growth of small semiconducting nanotubes.

Journal Article↗
PubMed2004

Application of a bio-electrochemical reactor process to direct treatment of metal pickling wastewater containing heavy metals and high strength nitrate.

The fundamental performance of a bio-electrochemical reactor for the direct treatment of metal pickling wastewater was investigated experimentally. In the reactor, carbon anode and cathode were installed. On the cathode, denitrifying microorganisms were immobilized. Continuous experiments were carried out by feeding a synthetic wastewater containing nitrate and binary heavy metal ions, copper and lead, under different operating conditions. Acetate as well as the electric current was supplied at the minimum amount for stoichiometry of the dissimilatory denitrification reaction. The results indicated that the dissolved copper and lead removal, denitrification and neutralization could be achieved simultaneously in a single bio-electrochemical reactor. The dissolved heavy metals were removed by electrochemical deposition on cathode and by the other phenomena such as the formation of insoluble suspensions and the sorption on suspended bacterial sludge. Denitrification proceeded effectively with the utilization of both added acetate and hydrogen gas generated by electrolysis of water. The pH value increased up to around neutral due to the occurrence of denitrification in the reactor, although the influent pH was less than 3. The removal efficiencies of heavy metals and nitrate increased with increasing the current density. The applied electric current was indispensable for sustaining the stable treatment in the reactor.

Acetates↗
PubMed2001

Mechanism of bifonazole-induced [Ca2+]i increases in MDCK renal tubular cells.

The effect of the antifungal drug bifonazole on Ca2+ homeostasis in Madin Darby canine kidney (MDCK) cells was investigated. Cell suspensions were loaded with the Ca2+-sensitive dye fura-2, and the fluorescence changes were measured with a spectrofluorophotometer. At concentrations between 10-80 microM bifonazole increased cytosolic free Ca2+ levels ([Ca2+]i) in a concentration-dependent manner. The Ca2+ signals were partly inhibited by removing extracellular Ca2+. Bifonazole (40 microM) released Ca2+ from the store sensitive to 1 microM thapsigargin, an endopolasmic reticulum Ca2+ pump inhibitor. Bifonazole (40 microM) per se induced capacitative Ca2+ entry while reduced 1 microM thapsigargin-induced capacitative Ca2+ entry. Inositol 1,4,5-trisphosphate may be involved in bifonazole-induced Ca2+ release because inhibiting phospholipase C with 2 microM U73122 partly reduced the bifonazole response. Together, bifonazole increased [Ca2+]i in renal tubular cells by inducing intracellular Ca2+ release and extracellular Ca2+ influx.

Adenosine Triphosphate↗
PubMed2001

Inhibition mechanisms of bioflavonoids extracted from the bark of Pinus maritima on the expression of proinflammatory cytokines.

The effect of bioflavonoids extracted from the bark of Pinus maritima, Pycnogenol (PYC), on gene expression of the proinflammatory cytokines interleukin-1beta (IL-1beta) and interleukin-2 (IL-2) were investigated in RAW 264.7 cells and Jurkat E6.1 cells, respectively. PYC exerted strong scavenging activities against reactive oxygen species (ROS) generated by H2O2 in RAW 264.7. In situ ELISA, immunoblot analysis, and competitive RT-PCR demonstrated that pretreatment of LPS-stimulated RAW 264.7 cells with PYC dose-dependently reduced both the production of IL-1beta and its mRNA levels. Furthermore, in the same cells, PYC blocked the activation of nuclear factor kappaB (NF-kappaB) and activator protein-1 (AP-1), two major transcription factors centrally involved in IL-1beta gene expression. Concordantly, pretreatment of the cells with PYC abolished the LPS-induced IkappaB degradation. We also investigated the effect of PYC on IL-2 gene expression in phorbol 12-myristate 13acetate plus ionomycin (PMA/Io)-stimulated human T-cell line Jurkat E6.1. PYC inhibited the PMA/Io-induced IL-2 mRNA expression. However, as demonstrated in a reporter gene assay system, the mechanism of IL-2 gene transcriptional regulation by PYC was different from the regulation of IL-1beta. PYC inhibited both NF-AT and AP-1 chloramphenicol acetyltransferase (CAT) activities in transiently transfected Jurkat E6.1, but not NF-kappaB CAT activity. We also found that PYC can destabilize PMA/Io-induced IL-2 mRNA by posttranscriptional regulation. All these results suggest that bioflavonids can be useful therapeutic agents in treating many inflammatory, autoimmune, and cardiovascular diseases based on its diverse action mechanisms.

Animals↗
PubMed2001

Spinal epidural extraskeletal Ewing sarcoma: MR findings in two cases.

SUMMARY: We report the CT myelography and MR findings of two cases of extraskeletal Ewing sarcoma involving the spinal epidural and paravertebral spaces in a middle-aged man (case 1) and a young woman (case 2). In both cases CT myelography showed epidural and paravertebral masses on one side, with widening of the ipsilateral neural foramina at the C5-C6 level in case 1 and at the C7-T1 level in case 2. On MR images, the masses were isointense to muscle on T1-weighted images, hyperintense on T2-weighted images, and showed moderate enhancement on contrast-enhanced T1-weighted images. In one case, all pulse sequences showed linear signal voids, representing the vertebral artery encasement within the mass. The intradural component connected with the main mass was detected in the other case.

Adult↗
PubMed2000

Effect of bioflavonoids extracted from the bark of Pinus maritima on proinflammatory cytokine interleukin-1 production in lipopolysaccharide-stimulated RAW 264.7.

Currently, bioflavonoids have been known to have strong antioxidant capacities, and a variety of efforts have been made to identify the utilities of bioflavonoids in treating various diseases based on their antioxidant capacities. The effects of bioflavonoids extracted from the bark of Pinus maritima Pycnogenol (PYC) on free radical formation, activation of redox sensitive transcription factors, as well as interleukin-1 beta (IL-1 beta) production were investigated in murine macrophage cell lines. PYC exerted strong scavenging activities against reactive oxygen species generated either by H(2)O(2) or PMA in RAW 264.7 and IC-21 cells, respectively. In situ ELISA, immunoblot analysis, and competitive RT-PCR demonstrated that PYC pretreatment of LPS-stimulated RAW 264.7 cells dose-dependently reduced both the production of IL-1 beta and its mRNA levels. Furthermore, in the same cells, PYC blocked the activation of nuclear factor kappa B (NF-kappa B) and activator protein-1 (AP-1), two major transcription factors centrally involved in IL-1 beta gene expression. When RAW 264.7 cells were stimulated with LPS, the inhibitor protein I kappa B largely disappeared from cytosolic fractions. However, pretreatment of the cells with PYC abolished the LPS-induced I kappa B degradation. These results suggest that PYC can inhibit the expression of the proinflammatory cytokine IL-1 by regulating redox-sensitive transcription factors. This study may support the possibility that bioflavonoids including PYC can be used as antiinflammatory and immunosuppressive drugs based on their radical scavenging activities.

Animals↗
PubMed2000

Chlorophyllin suppression of lipopolysaccharide-induced nitric oxide production in RAW 264.7 cells.

Chlorophyllin (CHL), a water-soluble derivative of chlorophyll, functions as an anticarcinogen and antioxidant. In the present study, we investigated the effect of CHL on nitric oxide production in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Treatment with CHL inhibited nitric oxide production in the LPS-stimulated RAW 264. 7 cells in a dose-related manner. Competitive RT-PCR analysis, using a DNA competitor as an internal standard, demonstrated that the treatment with 1, 10, and 50 microM CHL decreased LPS-induced iNOS mRNA expression in a concentration-dependent manner. Since the expression of the iNOS gene is mainly regulated by NF-kappaB, we then examined the effects of CHL on the NF-kappaB DNA binding activity, using an electrophoretic mobility shift assay. CHL down-regulated the NF-kappaB DNA binding on its cognate recognition site at the concentrations just noted. Employing a transfection and reporter gene expression system with p(NF-kappaB)(3)-chloramphenicol acetyl transferase (CAT), the treatment of CHL produced a dose-dependent inhibition of CAT activity in RAW 264.7 cells. Furthermore, CHL partially restored LPS-decreased IkappaBalpha, an inhibitory protein against NF-kappaB activation, in the cytosolic extract from the LPS-treated cells determined by immunoblot analysis. CHL also protected the hydroxyl radical-induced cytotoxicity in RAW 264.7 cells, indicating its antioxidant effect. These results suggest that CHL suppresses the nitric oxide production and iNOS mRNA expression mediated by the inhibition of NF-kappaB activation, and its action mechanism may be based on its antioxidant effect.

Animals↗
PubMed2000

Parachordoma of the tibia: report of a rare case.

We report a case of recurrent parachordoma of the left anterior tibial region in a 64-year-old male patient. The tumor was a periosteal tender mass, and, histologically, displayed vague nodules of spindle to rounded eosinophilic cells embedded in a myxoid matrix. Large vacuolated (physalphorouslike) cells were noted as in sacrococcygeal chordoma. This tumor should be differentiated from myxoid chondrosarcoma, myxoid liposarcoma, chondromyxoid fibroma, and metastatic chordoma. The presence of physaliphorous cells in the tumor with positive immunoreactions caused by cytokeratin rules out the diagnosis of another myxoid tumor. The differential diagnosis from metastatic chordoma is basically made by clinicians. Even though parachordoma is usually regarded as a benign soft tissue neoplasm, two recurrences occurred in our case. Since the reported cases, including ours, have diverse clinical courses, it is essential to follow-up the patient carefully.

Chondrosarcoma↗
PubMed2000

Basaloid squamous carcinoma of the oesophagus: a distinct neoplasm with multipotential differentiation.

AIMS: Basaloid squamous carcinoma (BSC) is an uncommon variant of squamous cell carcinoma, with its prevalent sites being the hypopharynx, tongue base and larynx. In the oesophagus, BSC is rarer than in the head and neck region. This study was aimed to document the clinicopathological features of BSCs of the oesophagus, and to present their relative incidence and immunohistochemical findings. METHODS AND RESULTS: Eighteen cases of BSC of the oesophagus, comprising 3.6% of 502 oesophageal carcinomas, were reviewed for their pathological and clinical features, and examined for the immunohistochemical expression of neuroendocrine markers, cytokeratins, p53, pRb and bcl-2. Oesophageal basaloid squamous carcinomas tended to be biphasic or multiphasic carcinomas, most commonly with basaloid and squamous components (eight cases), or with additional adenocarcinoma (three cases) or with small cell carcinoma (two cases). Each component was microscopically clearly distinguishable from the others, and metastasized separately, chiefly the basaloid component. The remaining five cases were apparently pure basaloid carcinomas, being characterized by lobules and nests of monotonous round undifferentiated cells with frequent comedo necrosis. They resembled, but were differentiated from, the small cell carcinoma on the basis of neuroendocrine markers and cytokeratin expression. p53, pRb and bcl-2 oncoprotein, which are known to normally present in the basal/parabasal cells of the oesophageal epithelium, were detected in 40-50% of cases, with a heterogeneous expression pattern. The patients were all male, with the age ranging 47-74 years (median 57) and presented at variable stages. The plotted 3 years survival rate was 51%, and the immunohistochemical expression of p53, pRb and bcl-2 was not related to the survival of the patients. CONCLUSION: Basaloid squamous carcinoma of the oesophagus is a peculiar neoplasm with a capacity of multidirectional differentiation, often with heterogeneous oncogene expression, probably reflecting the pluripotential stem cell origin.

Aged↗
PubMed2000

Sebaceous carcinoma of the eyelids: frequent expression of c-erbB-2 oncoprotein.

Ocular sebaceous carcinoma (OSC) is an uncommon malignancy with a potential to recur and metastasize. Some characteristics of sebaceous carcinoma, such as female preponderance, shown in the present series during 11-year period at Korea Cancer Center Hospital, led us to study their hormone receptors and c-erbB-2 expression. c-erbB-2 overexpression was very common (83%) in OSC, and was not associated with pathologic findings or clinical outcome. Interestingly, estrogen and progesterone receptor was detected in 4 and 2 cases, respectively, suggesting a role of hormonal influence on this neoplasm. Immunohistochemical and clinicopathologic features of 18 cases of OSC in Korea are presented.

Adult↗
PubMed2000

Catheter technique for pulmonary embolectomy or thrombofragmentation.

The management of acute massive pulmonary embolism (PE) constitutes a major clinical problem because of the associated derangement of hemodynamic and respiratory functions from obstruction to pulmonary blood flow. Despite advances in management with thrombolytic therapy or open embolectomy, the mortality rate remains high. To improve the chance of survival, catheter techniques that are capable of removing or fragmenting the clot have been developed. These include catheter pulmonary embolectomy and thrombofragmentation. The former involves the introduction of a suction catheter from a femoral or jugular venotomy through the right heart into the appropriate pulmonary artery under fluoroscopic guidance. The technique for the latter involves the percutaneous introduction of a fragmentation catheter from a femoral vein through a guiding catheter into the appropriate pulmonary artery. The success of the catheter technique in removing pulmonary emboli varies with different devices. The overall success rate is approximately 76%, with a mortality rate of 25%. Transvenous pulmonary embolectomy and thrombofragmentation are safe and effective techniques for treating patients with massive PE. The success of each of the techniques depends on a thorough understanding of the mechanism of action of each of the devices used and a facile catheterization technique.

Catheterization, Peripheral↗
PubMed1999

Reactive astrocytes express p53 in the spinal cord of transgenic mice expressing a human Cu/Zn SOD mutation.

In a previous study, we reported increased NOS expression in the astrocytes in the spinal cord of SOD mutant transgenic mice that are used as ALS animal model. Recently, Messmer and Brune suggested that nitric oxide-induced apoptosis is intimately related with p53-dependent signaling pathway, and de la Monte et al. reported increased p53-immunoreactivity in the spinal cord of ALS patients. In the present study, we performed immunocytochemical studies to investigate the changes of p53-immunoreactivity in the brains of the mutant transgenic mice expressing a human Cu/Zn SOD mutation. Immunocytochemistry showed intensely stained p53-IR glial cells with the appearance of astrocytes in all levels of the spinal cord of the mutant transgenic mice, but no p53-IR glial cells were observed in the spinal cord of the control mice. P53-IR astrocytes were also detected in the brain stem of the mutant transgenic mice. In the medulla, they were observed in the medullary reticular formation, hypoglossal nucleus, vestibular nucleus, dorsal motor nucleus of the vagus and nucleus ambiguus. In the pons, their presences were noted in the pontine reticular formation, and trigeminal and facial nuclei. In the midbrain, astrocytes were detected in the mesencephalic reticular formation, red nucleus and periaqueductal gray matter. In the cerebellum, intensely stained p53-IR astrocytes were detected in the intracerebellar nuclei. In contrast to the mutant transgenic mice, no p53-IR astrocytes were detected in the brain stem and spinal cord of the control mice. Further multidisciplinary investigations involving p53-mediated cellular damage and pathogenesis of ALS are needed to clarify the importance of these results.

Animals↗
PubMed1999

Proliferating cell nuclear antigen and c-erbB-2 oncoprotein expression in adenoid cystic carcinomas of the salivary glands.

BACKGROUND: Adenoid cystic carcinoma (ACC) of the salivary gland shows a variable clinical course. It would be helpful to discover reliable biologic markers in the management of patients with ACC. METHODS: We examined proliferating cell nuclear antigen (PCNA) and c-erbB-2 oncoprotein expression on 30 cases of ACC of the salivary glands. The immunohistochemical results, and size, location, and histologic grade of the tumors were compared with the clinical outcome of the patients. RESULTS: Mean PCNA positivity of ACCs was 15%, and was higher in solid than in cribriform/tubular areas. High PCNA value was significantly correlated with shorter disease-free and overall survival of the patients with ACC. c-erbB-2 overexpression was observed in only five cases, focally in cribriform/tubular areas. High histologic grade, which was determined by the presence of solid components, showed a trend toward shorter survival. Size and location of ACC were not associated with patient outcome. CONCLUSIONS: The present study indicates that PCNA score may be one of the most useful prognostic factor of ACC.

Adult↗
PubMed1999

Magnetic resonance imaging in renal transplantation.

End stage renal disease is common and can result from a variety of diseases. The expense and morbidity of dialysis has made renal transplantation the preferred treatment when it is available. In the United States, 11,000 renal transplants are performed annually. Because of the limited supply of donor organs, every effort is made to salvage the transplanted kidney that has began to fail. Imaging modalities that are currently used to evaluate transplanted kidneys are ultrasound (US), computed tomography (CT), scintigraphy, intravenous urography (IVU), contrast angiography, and magnetic resonance imaging (MRI). MRI offers multiple advantages. MRI provides cross sectional and vascular information without the risks of ionizing radiation, iodinated contrast, or arterial catheterization. This article describes the role of MR imaging in renal transplantation, technical aspects of image acquisition, and MR findings of post-transplantation complications.

Contrast Media↗
PubMed1999

Postoperative adjuvant therapy for stage II non-small-cell lung cancer.

BACKGROUND: Stage II non-small-cell lung cancer is regarded as one of the early lung cancers. Although resection, including the mediastinal lymph nodes, is currently regarded as the standard treatment, the survival rate of this disease is not encouraging. It is well known that the most common causes of death are locoregional recurrences or distant metastases, or both. However, the best adjuvant treatment to improve survival is as controversial an issue as ever. METHODS: This study was designed as a randomized, blinded, two-armed study with operation and adjuvant radiotherapy in one arm, versus operation and adjuvant mitomycin C (10 mg/m2), vinblastine (6 mg/m2), and cisplatin (100 mg/m2) (MVP) chemotherapy in the other arm. We assigned 57 resected patients with pathologic proven stage II non-small cell lung cancer to the groups according to our eligibility criteria. RESULTS: The most common pattern of recurrence was distant metastases, and nearly all the recurrences (17 of 18 patients) in both groups were found within 2 years after operation. The rates of the locoregional and distant metastases were 3.6% and 46.4% in the adjuvant radiotherapy group and 6.9% and 10.3% in the adjuvant chemotherapy group (p = 0.018). The 5-year disease-free survival rates were 52.0% in the adjuvant radiotherapy group and 74.0% in the adjuvant chemotherapy group (p = 0.16, log-rank test). The 2-year, 5-year, and 6-year survival portions were 60.3%, 56.5%, and 28.3% in the adjuvant radiotherapy group, and 82.8%, 70.1%, and 60.1% in the adjuvant chemotherapy group (p = 0.01, p = 0.17, and p = 0.03, Z-test). The difference of the actuarial survival between these two groups was somewhat significant (p = 0.09, log-rank test). CONCLUSIONS: Our results suggest that the addition of adjuvant MVP chemotherapy may reduce the distant metastasis rates and prolong the survival of the surgically resected stage II non-small-cell lung cancer patients.

Adult↗