Biomedical subjects

R H Kim

Publications and source records attributed to R H Kim.

At least 19 recordsLinked to original sources

PubMed2006

Elevated Bmi-1 expression is associated with dysplastic cell transformation during oral carcinogenesis and is required for cancer cell replication and survival.

Bmi-1 is a polycomb group protein that was identified as c-myc cooperating oncogene in murine lymphomagenesis. The current study was undertaken to determine the role of Bmi-1 in human oral carcinogenesis. Bmi-1 protein and RNA expression levels were markedly enhanced in the cells of oral squamous cell carcinomas (OSCC) compared with that of normal human oral keratinocytes (NHOK). Enhanced-Bmi-1 expression was also detected in situ in the archived oral mucosal tissues with cancerous and precancerous histopathology, including that of mild epithelial dysplasia. Thus, Bmi-1 expression occurs at a very early stage in oral carcinogenesis. To determine the biological role of Bmi-1 in cell proliferation, endogenous Bmi-1 was knocked down in actively proliferating SCC4 cells and NHOK by RNA interference. After Bmi-1 knockdown, cell replication was severely retarded. However, the expression of p16(INK4A), a known cellular target of Bmi-1, was not changed in cells with or without Bmi-1 knockdown. Furthermore, Bmi-1 knockdown in HOK-16B-BaP-T cells, in which the p16(INK4A)/pRb pathway was abrogated, led to immediate arrest of replication and loss of viable cells. Thus, our data suggest that Bmi-1 may act through p16(INK4A)-independent pathways to regulate cellular proliferation during oral cancer progression.

Carcinoma, Squamous Cell↗

PubMed2006

Tumours and tremors: how PTEN regulation underlies both.

Mutations of the tumour suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10) are seen in many human cancers. However, dysregulation of PTEN may be involved in other disease states such as Parkinson's disease. This minireview describes recent work examining PTEN regulation and its implications for the development of both cancer and neurodegenerative disease.

Animals↗

PubMed2005

Developing technologies for rainwater utilization in urbanized area.

Rainwater utilization has potential to recover the hydrological cycle, to buffer extreme run-off situations in the watercourses, and to reduce the costs for water supply in urban areas. However, relatively few works have been done for developing technologies to improve the water quality during rainwater utilization in large cities where the contamination of rainwater is anticipated. Therefore, this study focused on developing technologies for rainwater utilization subsystems including catchment, storage, treatment, infiltration, and use for buildings in urban areas. The rainwater samples collected from roof and roof garden were compared with wet deposition to analyze and identify the major components that may cause problems in rainwater utilization. Based on these results, novel techniques utilizing TiO2, sunlight, and bauxsol to minimize the contamination level by particles, microorganisms, and nutrients were developed for rainwater subsystems and applied to explore their suitability.

Cities↗

PubMed2005

Pollutants in rainwater runoff in Korea: their impacts on rainwater utilization.

Frequent urban floods and insufficient water supply have led to developing technologies for rainwater utilization in order to buffer extreme runoff situations in the watercourses and to provide an ongoing water supply for non-potable use. However, little information is available on the water qualities and runoff properties of collected rainwater in connection with efficient design and maintenance strategies of rainwater utilization systems. In this work, the characteristics of rainwater were investigated in a full-scale rainwater utilization facility in Korea. Samples of runoff rainwater from various catchment surfaces were analyzed for physico-chemical and microbial determinants including metals, nutrients, pH, turbidity, conductivity, and microorganisms. The pollutant concentrations in rainwater storage tank were also monitored to elucidate the impact of input rainwater quality on stored water property. It is likely that particles and total coliforms are major issues in operating rainwater utilization system. However, further studies will be necessary to address the health effect of rainwater in terms of microbial and ecotoxicological measures.

Conservation of Natural Resources↗

PubMed2002

Long-term neuropsychological effects and MRI findings in patients with CS2 poisoning.

OBJECTIVES: To evaluate the long-term neuropsychological effects and magnetic resonance imaging (MRI) findings among retired patients with a history of exposure to carbon disulfide (CS2). MATERIAL AND METHODS: Seventy-four patients with a history of exposure to CS2 were divided into two equal groups according to their level of exposure, and they completed a questionnaire and were evaluated for neuropsychological symptoms using the Korean version of the revised Wechsler Adult Intelligence Scale. Thirty-one MRI images were reviewed retrospectively. RESULTS: There were no statistically significant differences in total, verbal and performance IQs between high- and low-exposure groups. MRI findings revealed a significantly larger number of cerebral lacunae (five of 12 subjects) in the high-exposure group. Periventricular hyperintensities were mostly located in frontal and occipital areas, and white-matter hyperintensities were mostly in frontal and parietal areas. CONCLUSION: The higher prevalence of lacunae in the high-exposure group as revealed by MRI suggests that further MRI studies are needed into long-term neuropsychological effects induced by CS2.

Aged↗

PubMed2002

Application of membrane-coupled anaerobic volatile fatty acids fermentor for dissolved organics recovery from coagulated raw sludge.

To investigate the treatment performance of membrane-coupled anaerobic volatile fatty acids fermentor system, the effects of operational parameters for volatile fatty acids production were evaluated through experiments and a mathematical model. The volatile fatty acids recovery ratio was largely affected by the change of hydraulic retention time, reaching its maximum value at 12 hrs. Over the range of hydraulic retention time 8 to 96 hrs, the volatile fatty acids recovery ratio decreased with the increase of hydraulic retention time above 12 hrs, while the ratio of mineralization and gasification increased. Hydraulic retention time and membrane filtration ratio should be maintained less than 1 day and above 0.9, respectively, to attain over 40% of organic materials recovery ratio at 10 days of solids retention time. When the hydrolysis rate constant was 0.01 hr-1, the organic loading rate should be maintained at above 1.0 (kgC/m3/day) to attain over 45% of volatile fatty acids recovery ratio. Based on experimental and simulated results, membrane-coupled anaerobic volatile fatty acids fermentor system was thought to be effective for dissolved organics recovery from coagulated sewage sludge.

Bacteria, Anaerobic↗

PubMed2001

SNIP1 inhibits NF-kappa B signaling by competing for its binding to the C/H1 domain of CBP/p300 transcriptional co-activators.

SNIP1 is a 396-amino acid nuclear protein shown to be an inhibitor of the TGF-beta signal transduction pathway and to be important in suppressing transcriptional activation dependent on the co-activators CBP and p300. In this report we show that SNIP1 potently inhibits the activity of NF-kappa B, which binds the C/H1 domain of CBP/p300, but does not interfere with the activity of transcription factors such as p53, which bind to other domains of p300, or factors such as VP16, which are independent of these co-activators. Inhibition of NF-kappa B activity is a function of the N-terminal domain of SNIP1 and involves competition of SNIP1 and the NF-kappa B subunit, RelA/p65, for binding to p300, similar to the mechanism of inhibition of Smad signaling by SNIP1. Immunohistochemical staining shows that expression of SNIP1 is strictly regulated in development and that it colocalizes, in certain tissues, with nuclear staining for RelA/p65 and for p300, suggesting that they may regulate NF-kappa B activity in vivo in a spatially and temporally controlled manner. These data led us to suggest that SNIP1 may be an inhibitor of multiple transcriptional pathways that require the C/H1 domain of CBP/p300.

Animals↗

PubMed2001

Ceruloplasmin enhances DNA damage induced by cysteine/iron in vitro.

Ceruloplasmin (Cp) was found to promote the oxidative damage to DNA in vitro, as evidenced by the formation of 8-hydroxy-2'-deoxyguanosine and strand breaks, when incubated with a cysteine metal-catalyzed oxidation system (Cys-MCO) comprised of Fe(3+), O(2), and cysteine as an electron donor. The capacity of Cp to enhance oxidative damage to DNA was inhibited by hydroxyl radical scavengers such as sodium azide and mannitol, a metal chelator, diethylenetriaminepentaacetic acid, a spin-trapping agent, 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and catalase. Ceruloplasmin also caused the two-fold enhancement of a mutation in the pUC18 lacZ' gene in the presence of Cys-MCO when measured as a loss of alpha-complementation. Incubation of Cp with Cys-MCO resulted in an increase in the content of carbonyl groups and the significant alteration of the ferroxidase activity, as well as the proteolytic susceptibility. The deoxyribose assay and the salicylate hydroxylation assay showed that hydroxyl free radicals were generated in the reaction of Cp with Cys-MCO. The release of a portion of Cu from Cp was observed, and conformational alterations were indicated by the changes in fluorescence spectra. Based on these results, we interpret the enhancing effect of Cp on DNA damage and mutagenicity induced by Cys-MCO as due to reactive oxygen species, probably hydroxyl free radicals, formed by the reaction of free Cu(2+), released from oxidatively damaged Cp, and H(2)O(2) produced by Cys-MCO. The release of Cu from Cp during oxidative stress could enhance the formation of reactive oxygen species and could also potentiate cellular damage.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2001

The molecular basis of O2-sensing and hypoxia tolerance in pheochromocytoma cells.

Hypoxia is a common environmental stimulus. However, very little is known about the mechanisms by which cells sense and respond to changes in oxygen. Our laboratory has utilized the PC12 cell line in order to study the biophysical and molecular response to hypoxia. The current review summarizes our results. We demonstrate that the O2-sensitive K(+) channel, Kv1.2, is present in PC12 cells and plays a critical role in the hypoxia-induced depolarization of PC12 cells. Previous studies have shown that PC12 cells secrete a variety of autocrine/paracrine factors, including dopamine, norepinephrine, and adenosine during hypoxia. We investigated the mechanisms by which adenosine modulates cell function and the effect of chronic hypoxia on this modulation. Finally, we present results identifying the mitogen- and stress-activated protein kinases (MAPKs and SAPKs) as hypoxia-regulated protein kinases. Specifically, we show that p38 and an isoform, p38gamma, are activated by hypoxia. In addition, our results demonstrate that the p42/p44 MAPK protein kinases are activated by hypoxia. We further show that p42/p44 MAPK is critical for the hypoxia-induced transactivation of endothelial PAS-domain protein 1 (EPAS1), a hypoxia-inducible transcription factor. Together, these results provide greater insight into the mechanisms by which cells sense and adapt to hypoxia.

Animals↗

PubMed2000

A novel smad nuclear interacting protein, SNIP1, suppresses p300-dependent TGF-beta signal transduction.

Members of the transforming growth factor-beta superfamily play critical roles in controlling cell growth and differentiation. Effects of TGF-beta family ligands are mediated by Smad proteins. To understand the mechanism of Smad function, we sought to identify novel interactors of Smads by use of a yeast two-hybrid system. A 396-amino acid nuclear protein termed SNIP1 was cloned and shown to harbor a nuclear localization signal (NLS) and a Forkhead-associated (FHA) domain. The carboxyl terminus of SNIP1 interacts with Smad1 and Smad2 in yeast two-hybrid as well as in mammalian overexpression systems. However, the amino terminus of SNIP1 harbors binding sites for both Smad4 and the coactivator CBP/p300. Interaction between endogenous levels of SNIP1 and Smad4 or CBP/p300 is detected in NMuMg cells as well as in vitro. Overexpression of full-length SNIP1 or its amino terminus is sufficient to inhibit multiple gene responses to TGF-beta and CBP/p300, as well as the formation of a Smad4/p300 complex. Studies in Xenopus laevis further suggest that SNIP1 plays a role in regulating dorsomedial mesoderm formation by the TGF-beta family member nodal. Thus, SNIP1 is a nuclear inhibitor of CBP/p300 and its level of expression in specific cell types has important physiological consequences by setting a threshold for TGF-beta-induced transcriptional activation involving CBP/p300.

Amino Acid Sequence↗

PubMed2000

Parathyroid hormone regulation of bone sialoprotein (BSP) gene transcription is mediated through a pituitary-specific transcription factor-1 (Pit-1) motif in the rat BSP gene promoter.

Bone sialoprotein (BSP) is a mineralized tissue-specific protein expressed by differentiated osteoblasts that appears to function in the initial mineralization of bone. Parathyroid hormone (PTH), which regulates serum calcium through its actions on bone cells, increases the expression of BSP in the rat osteosarcoma cell line (ROS 17/2.8). At 10(-8) M PTH (human 1-34 PTH), stimulation of BSP mRNA was first evident at 3 h ( approximately 3.8-fold), reached maximal levels at 6 h ( approximately 4.7-fold), and declined slowly thereafter. The effects of PTH, which were abrogated by cycloheximide (28 microg/ml), did not alter the stability of the BSP mRNA. The increased transcription was mimicked by both forskolin (10(-6) M) and isoproterenol (10(-7) M), and was also increased by 3-isobutyl-1-methylxanthine (IBMX; 10(-5) M), while the transcriptional activity induced by PTH was inhibited by the protein kinase A inhibitor, H89 (5x10(-6) M). From transient transfection assays using various BSP promoter-luciferase constructs, a pituitary-specific transcription factor-1 (Pit-1) regulatory element (nts -111 to -105) was identified as the target of transcriptional activation by PTH. Thus, transcriptional activity of constructs including the Pit-1 was enhanced approximately 4.7-fold by 10(-8) M PTH while 5'-ligation of the Pit-1 element conferred PTH regulation in an SV40 promoter construct. Binding of a nuclear protein, recognized by anti-Pit-1 antibodies, to a radiolabelled Pit-1-BSP probe was decreased in nuclear extracts prepared from PTH, forskolin and isoproterenol-stimulated ROS 17/2.8 cells. Moreover, co-transfection of ROS cells with a double-stranded Pit-1 oligonucleotide also increased luciferase activity. Collectively, these results indicate that PTH acts through a protein kinase A pathway involving cAMP to stimulate BSP transcription by blocking the action of a Pit-1-related nuclear protein that suppresses BSP transcription by binding a cognate element in the BSP promoter. Thus, we have identified a novel Pit-1 suppressor element in the rat BSP gene promoter that is the target of PTH-stimulated transcription of the BSP gene.

Amino Acid Motifs↗

PubMed2000

Ceruloplasmin enhances DNA damage induced by hydrogen peroxide in vitro.

Ceruloplasmin (Cp) was found to promote the oxidative damage to DNA, as evidenced by the formation of 8-hydroxy-2'-deoxyguanosine and strand breaks, when incubated with H2O2 in vitro. The capacity of Cp to enhance oxidative damage to DNA was inhibited by hydroxyl radical scavengers such as sodium azide and mannitol, a metal chelator, diethylenetriaminepentaacetic acid, and catalase. Although the oxidized protein resulted in an increase in the content of carbonyl groups, the ferroxidase activity and the proteolytic susceptibility were not significantly altered. The release of a portion of Cu from Cp was observed, and conformational alterations were indicated by the changes in fluorescence spectra. Based on these results, we suggest that damage to DNA is mediated in the H2O2/Cp system via the generation of *OH by released Cu2+ and/or loosely bound Cu exposed from oxidatively damaged Cp through the conformational change. The release of Cu from Cp during oxidative stress could enhance the formation of reactive oxygen species and could also potentiate cellular damage.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1999

Transcription of the bone sialoprotein gene is stimulated by v-Src acting through an inverted CCAAT box.

Bone sialoprotein (BSP) is an early marker of differentiated osteoblasts that has been implicated in the nucleation of hydroxyapatite crystal formation during de novo bone formation. Although essentially specific to mineralizing connective tissues, BSP is also expressed ectopically by carcinomas that exhibit microcalcification and which metastasize to bone with high frequency. However, it is not known how BSP is regulated in transformed cells. Because the v-src oncogene induces expression of a number of genes that are involved in tumor growth and metastasis, including osteopontin, we have studied the effects of v-Src on transcription of the BSP gene. Transfection of mouse src-/- cells with a v-src expression vector increased the transcriptional activity of rat BSP promoter/luciferase chimeric constructs approximately 5-fold. Deletion analysis revealed that the v-Src activity was targeted to an inverted CCAAT box located immediately upstream from an inverted TATA box in the BSP promoter. Although mutation of the CCAAT box diminished the basal transcription activity of the BSP promoter, the Src-induced stimulation was completely abolished. Gel mobility shift analysis identified four nuclear factors that bound to this region of the BSP promoter, two of which required an intact CCAAT sequence. Monoclonal antibodies identified nuclear factor-Y (NF-Y) as the principal nuclear factor that bound to the CCAAT box; the second factor (beta) showing strong binding only in short constructs containing the CCAAT sequence. Transcription analyses with a dominant negative NF-Y expression vector confirmed that NF-Y mediated the action of v-Src. These studies indicate that BSP gene expression in transformed cells can be up-regulated by Src kinase activity through a mechanism mediated by the NF-Y transcription factor, which targets an inverted CCAAT box in the BSP gene promoter.

3T3 Cells↗

PubMed1999

Bone sialoprotein.

The search for a protein nucleator of hydroxyapatite crystal formation has been a focus for the isolation and characterization of the major non-collagenous proteins in bone. Of the proteins characterized to date, bone sialoprotein (BSP) has emerged as the only bona fide candidate for nucleation. BSP is a highly glycosylated and sulphated phosphoprotein that is found almost exclusively in mineralized connective tissues. Characteristically, polyglutamic acid and arginine-glycine-aspartate (RGD) motifs with the ability to bind hydroxyapatite and cell-surface integrins, respectively, have been conserved in the protein sequence. Expression of the BSP gene, which is induced in newly formed osteoblasts, is up-regulated by hormones and cytokines that promote bone formation and down-regulated by factors that suppress bone formation. Thus, BSP has the biophysical and chemical properties of a nucleator, and its temporo-spatial expression coincides with de novo mineralization in bone and cementum. Moreover, BSP has been associated with mineral crystal formation in several pathologies, including breast carcinomas. However, the ability of BSP to mediate cell attachment and to signal through the RGD motif points to alternate functions for BSP which need further investigation. In combination, the hydroxyapatite-binding polyglutamic acid sequences and the RGD provide bi-functional entities through which BSP may mediate the targeting and attachment of normal and metastasizing cells to the bone surface.

Amino Acid Sequence↗

PubMed1998

Rheolytic thrombectomy of chronic coronary occlusion.

Percutaneous intervention in patients with intracoronary thrombus continues to pose a significant clinical challenge. In this report, we describe the successful treatment of a 44-year-old patient with an extensive chronic thrombotic occlusion of the right coronary artery using a rheolytic thrombectomy catheter. Despite angiographic documentation of coronary thrombosis 104 days prior to treatment and a voluminous thrombus burden (60 mm in length x 3 mm in diameter), rapid recanalization was accomplished with this device without embolic complications. At 1 year clinical follow-up, the patient has remained symptom free. The design of this novel device and its mechanism of action are described.

Adult↗

PubMed1998

Enhancement by copper, zinc superoxide dismutase of DNA damage and mutagenicity with hydrogen peroxide.

Oxidative DNA damage caused by hydrogen peroxide was enhanced by copper, zinc superoxide dismutase (CuZnSOD) in a concentration-dependent manner, as reflected by the formation of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) and strand breaks. Hydroxyl radical scavengers such as sodium azide, mannitol and 5,5-dimethyl-1-pyrroline N-oxide (DMPO), a metal chelator, diethylenetriamine-pentaacetic acid, and catalase decreased strand breaks and 8-OH-dG formation in DNA. The deoxyribose assay showed that hydroxyl free radicals were generated in the reaction of CuZnSOD with H2O2. CuZnSOD also caused enhancement of mutation in the pUC18 lacZ' gene in the presence of H2O2 when measured as a loss of alpha-complementation. Based on these results, we interpret the effects of CuZnSOD on hydrogen peroxide induced DNA damage and mutation as due to reactive oxygen species, probably hydroxyl free radicals, formed predominantly by the reaction of hydrogen peroxide and free Cu2+ released from oxidatively damaged CuZnSOD.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1998

Characteristics of vitamin D3 receptor (VDR) binding to the vitamin D response element (VDRE) in rat bone sialoprotein gene promoter.

Bone sialoprotein (BSP) is a mineralised tissue-specific protein that is highly expressed during the initial formation of bone and cementum. Expression of BSP is suppressed by the osteotropic hormone, 1,25-dihydroxyvitamin D3 (vitamin D3), which regulates bone remodelling. In previous studies, we have identified a vitamin D response element (VDRE) that is integrated with a novel inverted TATA box in the rat BSP promoter which mediates the suppression of BSP transcription (1). Although the nucleotide sequences of VDREs in different genes conform to a direct (hexamer) repeat, spaced by three nucleotides, the precise sequences are unique for each VDRE. To determine whether the nucleotide differences in the VDRE influence VDR binding, we have compared interactions of VDR proteins with various VDREs using gel mobility shift analysis. Both natural and recombinant VDRs bound to rat BSP and both mouse and porcine osteopontin (OPN) VDRE oligonucleotides in a concentration-dependent manner with a strong preference for dimer formation, whereas equal amounts of dimer and monomer were bound to the human osteocalcin VDRE. However, whereas a truncated VDR comprising the DNA binding domain alone bound the mouse osteopontin VDRE, it failed to interact with the porcine OPN and rat BSP VDREs. VDR binding to the BSP was sequence specific, as shown by mutagenesis analysis, and could be abolished by heat and VDR antibody. These studies demonstrate that subtle differences in the nucleotide sequence of VDREs affect VDR binding, which mediates the vitamin D3 response.

Animals↗

PubMed1997

Transforming growth factor-beta 1 regulation of bone sialoprotein gene transcription: identification of a TGF-beta activation element in the rat BSP gene promoter.

Transforming growth factor-beta (TGF-beta) increases steady-state mRNA levels of several extracellular matrix proteins in mineralized connective tissues. Bone sialoprotein (BSP) is a major constituent of the bone matrix, thought to initiate and regulate the formation of mineral crystals. To determine the molecular pathways of TGF-beta 1 regulation of bone proteins, we have analyzed the effects of the TGF-beta 1 on the expression of the BSP in the rat osteosarcoma cell line (ROS 17/2.8). TGF-beta 1 at 1 ng/ml, increased BSP mRNA levels in ROS 17/2.8 cells approximately 8-fold: the stimulation was first evident at 3 hr, reached maximal levels at 12 hr and slowly declined thereafter. Since the stability of the BSP mRNA was not significantly affected by TGF-beta 1, and nuclear "run-on" transcription analyses revealed only a approximately 2-fold increase in the transcription of the BSP gene, most of the increase in BSP mRNA appeared to involve a nuclear post-transcriptional mechanism. Moreover, the effects of TGF-beta 1 were indirect, since the increase in BSP mRNA was abrogated by cycloheximide (28 micrograms/ml). To identify the site of transcriptional regulation by TGF-beta 1, transient transfection analyses were performed using BSP gene promoter constructs linked to a luciferase reporter gene. Constructs that included nt -801 to -426 of the promoter sequence were found to enhance transcriptional activity approximately 1.8-fold in cells treated with TGF-beta 1. Within this sequence, approximately 500 nt upstream of the transcription start site, a putative TGF-beta activation element (TAE) was identified that contained the 5'-portion of the nuclear factor-1 (NF-1) canonical sequence (TTGGC) overlapping a consensus sequence for activator protein-2 (AP-2). The functionality of the TAE was shown by an increased binding of a nuclear protein from TGF-beta 1 stimulated cells in gel mobility shift assays and from the attenuation of TGF-beta 1-induced luciferase activity when cells were co-transfected with a double-stranded TAE oligonucleotide. Competition gel mobility shift analyses revealed that the nuclear protein that binds to the TAE has similar properties to, but is distinct from, NF-1 nuclear protein. These studies have therefore identified a TGF-beta activation element (TAE) in the rat BSP gene promoter that mediates the stimulatory effects of TGF-beta 1 on BSP gene transcription.

Animals↗