Biomedical subjects
Publications and source records attributed to Tae-Hwan Kim.
Acute leukemia is uncommonly seen with rheumatoid arthritis during or following treatment with low-dose methotrexate, a safe and effective treatment for the arthritic condition. We describe here a 68-year-old woman with rheumatoid arthritis who developed acute erythroleukemia during low-dose methotrexate therapy (total dose 1702.5 mg). This may be the first such case reported in the literature.
It has been well known that Ras signaling is involved in various cellular processes, including proliferation, differentiation, and apoptosis. However, distinct cellular functions of Ras isozymes are not fully understood. Here we show the opposing roles of Ha-Ras and Ki-Ras genes in the modulation of cell sensitivity to ionizing radiation. Overexpression of active isoform of Ha-Ras (12V-Ha-Ras) in Rat2 cells increases resistance to the ionizing radiation. Constitutive activation of phosphoinositide-3-kinase (PI3K) and Akt is detected specifically in 12V-Ha-Ras-overexpressing cells. The specific PI3K inhibitor LY294002 inhibits PI3K/Akt signaling and potentiates the radiation-induced apoptosis, suggesting that activation of the PI3K/Akt signaling pathway is involved in the increased radio-resistance in cells overexpressing 12V-Ha-Ras. Overexpression of activated Ki-Ras (12V-Ki-Ras), on the other hand, markedly increases radiation sensitivity. The p38 mitogen-activated protein kinase (MAPK) activity is selectively enhanced by ionizing radiation in cells overexpressing 12V-Ki-Ras. The specific p38 MAPK inhibitor, PD169316, or dominant-negative p38 MAPK decreases radiation-induced cell death. We further show that the mechanism that underlies potentiation of cell death in cells overexpressing 12V-Ki-Ras involves Bax translocation to the mitochondrial membrane. Elevated Bax translocation following ionizing irradiation in 12V-Ki-Ras-overexpressing cells is completely inhibited by PD169316 or dominant-negative p38 MAPK. In addition, introduction of cells with RacN17, a dominant-negative mutant of Rac, resulted in a marked inhibition of radiation-induced Bax translocation and apoptotic cell death as well as p38 MAPK activation. Taken together, these findings explain the opposite effects of Ha-Ras and Ki-Ras on modulation of radiosensitivity, and suggest that differential activation of PI3K/Akt and Rac/p38 MAPK signaling by Ha-Ras and Ki-Ras may account for the opposing response to the ionizing radiation. These data provide an explanation for the diverse biological functions of Ras isozymes, and partly accounts for the differential response of transformed cells to anticancer treatments.
The effect of food waste (FW) composted with MS (Miraculous Soil Microorganisms) was compared with commercial compost (CC) and mineral fertilizer (MF) on bacterial and fungal populations, soil enzyme activities and growth of lettuce in a greenhouse. Populations of fungi and bacteria, soil biomass, and soil enzyme activities in the rhizosphere of FW treatments significantly increased compared to control (CON), CC and MF treatments at 2, 4, and 6 weeks. The fresh weight of lettuce in FW treatments was about 2-3 times higher than that in CC at 4 and 6 week. The pH, EC, total nitrogen content, organic matter and sodium concentration in FW treatments were generally higher than those in CON, CC and MF treatments.
The mechanisms whereby arthritogenic organisms may induce cartilage and bone erosions in infection-triggered arthritis remain unknown. In this study, we asked whether an arthritogenic organism could contribute to osteoclast differentiation and activation through regulation of the receptor activator of NF-kappaB ligand (RANKL) in synovial fibroblasts. Rat synovial fibroblasts were infected in vitro with Salmonella enterica serovar Typhimurium and monitored over time. The expression of RANKL in resting and infected synovial fibroblasts was quantified by reverse transcription-PCR and Western blotting. Osteoclast progenitors, isolated from femurs of 8-week-old rats and cultured in the presence of macrophage colony-stimulating factor, were cocultured with either infected or noninfected synovial fibroblasts for 2 to 4 days. Differentiation and maturation of osteoclasts were determined by morphology and tartrate-resistant acid phosphatase (TRAP) staining and by a bone resorption bioassay. RANKL expression was undetectable in resting synovial fibroblasts but was dose-dependently upregulated in cells after Salmonella infection. Osteoprotegerin was constitutively expressed by synovial fibroblasts and was not upregulated by infection. Further, we observed the formation of multinucleated TRAP-positive cells and formation of bone resorption pits in cocultures of bone marrow-derived osteoclast precursors with synovial fibroblasts infected with Salmonella but not with heat-killed Salmonella or noninfected cells. Arthritogenic bacteria may alter bone structure via synovial fibroblast intermediaries, since infected synovial fibroblasts (i) upregulate RANKL expression and (ii) enhance osteoclast precursor maturation into multinucleated, TRAP-positive, bone-resorbing, osteoclast-like cells. These data provide a link between infection and osteoclastogenesis. A better understanding of infection-mediated osteoclast differentiation and activation may provide new therapeutic strategies for inflammatory joint disease.
BACKGROUND: Interaction of the integrin leukocyte function-associated antigen (LFA)-1 (CD11a/CD18) with its ligands, the intercellular adhesion molecules (ICAM)-1, -2, and -3 (CD54, CD102, and CD50), is pivotal to many leukocyte adhesion events. METHOD: To define the mechanism of the movement of leukocytes to the inflammatory site by somatostatin (SOM) and substance P (SP), we examined the expression of the adhesion molecule LFA-1 and inside-out signals for integrins, protein kinase C (PKC), Ras, Rap1, and phosphoinositide (PI) 3-kinase, in anti-CD3-, anti-CD3+SOM-, anti-CD3+SP-stimulated or unstimulated spleen cells. RESULTS: SOM caused down-regulation of LFA-1 mRNA translation as well as of adhesion-stimulating molecules such as Rap1, Ras, and PI 3-kinase. On the other hand, SP slightly induced LFA-1 mRNA translation and activation signals for integrins. The early-phase alteration of LFA-1 mRNA translation after 3 h of culture may be due to the changes of CD8+ T cells rather than changes of CD4+ cells. In adhesion assays, SOM significantly decreased cell adhesion (p < 0.05). CONCLUSION: These data suggest that SOM treatment of spleen cells, especially in CD8+ T cells, leads to downregulation of LFA-1 mRNA translation, inside-out signaling molecules for integrins (Ras, Rap1 and PI 3-kinase, but not PKC), and consequently to a decrease in the LFA-1-mediated adhesion to ICAM-1.
Severe systemic manifestations of adult onset Still's disease (AOSD) are often fatal and occasionally related to hemophagocytic syndrome (HS). We describe the case of a 49-yr-old woman with AOSD presenting with non-remitting high fever, confusion, jaundice, hepatosplenomegaly, serositis, azotemia, pancytopenia, coagulopathy with disseminated intravascular coagulation (DIC), hyperferritinemia, acute acalculous cholecystitis and ileocolitis noted in computed tomographic images. The patient had a history of herpes zoster developed prior to the admission, but there is no history of diarrhea or abdominal pain. Although bone marrow examination was not performed due to hemorrhagic diathesis, we suspected AOSD-associated HS on the basis of clinical course without detectable infectious agents in cultures or serologic studies. Intravenous immunoglobulin, pulse methylprednisolone, oral cyclosporine A (CsA) and ceftriaxone brought about transient improvement of fever and confusion, but the disease progressed. After increasing CsA dose, all previously mentioned abnormalities disappeared rapidly. Accordingly, we believe that DIC and multiple organ dysfunctions might have been the complications of HS but not that of sepsis, and that CsA can be used as a first-line therapy in case of life-threatening situations.
OBJECTIVE: Substantial epidemiological and genetic evidence suggests that ankylosing spondylitis (AS) is likely due to an interplay of genetic and environmental factors. Recently, CARD15, located in chromosome 16q12, has been established as a disease susceptibility gene for Crohn's disease, Blau syndrome, and possibly psoriatic arthritis. Association studies in admixed populations from Northern European ancestry noted no such association between CARD15 mutations and AS. However, a homogenous population has yet to be studied. We investigated the prevalence of the 3 common CARD15 variants in a homogenous Korean population with AS. METHODS: All subjects were native Koreans with AS satisfying the modified New York criteria. Korean controls were examined and confirmed to be unaffected by AS. Subjects with AS were genotyped for the R702W, G908R, and Leu1007fsinsC variants of CARD15 using mass array MALDI-TOF mass spectrometry. RESULTS: A total of 205 AS subjects and 200 controls were genotyped. No subject with AS had any variants at the 702 and 1007 sites of CARD15. Only one subject was heterozygous for the 908 variant. The overall genotype frequency in AS for any CARD15 variant was 0.5%. No control had any of the 3 CARD15 variants. CONCLUSION: Our findings indicate that the CARD15 gene is not a major contributor to AS susceptibility in the Korean population.
OBJECTIVE: To examine whether the high incidence of herpes zoster in patients with systemic lupus erythematosus (SLE) is associated with the frequency of memory T cells specific to varicella zoster virus (VZV). METHODS: Whole blood samples from 47 subjects [24 patients with SLE, 11 with rheumatoid arthritis (RA) as a disease control, and 12 healthy negative controls] were stimulated with VZV antigen, stained for surface CD4 and CD8 and intracellularly stained for the cytokines interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin 4 (IL-4), and IL-10, followed by flow cytometry analyses. Correlations of VZV-specific T cell frequencies with the clinical status of patients were analyzed. RESULTS: Percentage of IFN-gamma-positive CD4 T cells was significantly lower in patients with SLE (0.043 +/- 0.009%) than in RA (0.102 +/- 0.019%) and healthy controls (0.126 +/- 0.025%) upon VZV stimulation. A similar pattern was seen in TNF-alpha-positive CD4 T cell responses. These low frequencies of VZV-specific CD4 T cells in patients with SLE were significantly related with disease activity (r = -0.435, p = 0.043). CONCLUSION: These data suggest that the high incidence of herpes zoster in patients with SLE was related to the intrinsic defects in controlling VZV reactivation, and thus VZV-specific CD4 T cell frequency could be another practical risk factor of herpes zoster in patients with SLE.
A 27-year-old female lowland gorilla developed an asymmetric oligoarthritis 3 months post-partum. There was no evidence of an antecedent gastrointestinal or genitourinary infection. Serum was negative for rheumatoid factor and antinuclear antibody. Synovial fluid revealed 2000 white blood cells with negative cultures and polarized microscopy. Studies on synoviocytes were the following: (1) FACS analysis revealed surface expression of a B27-like epitope of the cells. (2) Analysis of intracellular clearance kinetics of arthritogenic organisms showed peak intracellular colony-forming units at 48 hours after bacterial invasion, and clearance by 13 days post-invasion. (3) Interferon-y (0.1-10.0 ng/ml)accelerated intracellular microbicidal pathways in a dose-dependent fashion. These findings closely parallel those seen in human synoviocytes of patients with spondyloarthropathy. Primate and human seronegative arthritis share clinical and immunologic features, as well as aspects of host:pathogen defense mechanisms. The interplay of genetic and microbial factors underlying this arthritis appears to be conserved across these species boundaries.
OBJECTIVE: The aim of this study was to determine the clinical and genetic risk factors that influence herpes zoster occurrence in patients with systemic lupus erythematosus (SLE). METHODS: Three hundred three SLE patients meeting the American College of Rheumatology criteria were enrolled in this study. Herpes zoster was diagnosed when classic grouped vesicles were noted. Medical records were reviewed retrospectively to collect clinical information. For Fc gamma receptor IIa (Fc gamma RIIa) and Fc gamma RIIIa genotyping, polymerase chain reaction (PCR) using allele-specific primers was performed. The PCR sequence-specific oligonucleotide probe method was utilized in human HLA-DRB1 genotyping. RESULTS: Forty-two cases (13.9%) of zoster occurred among 303 SLE patients. The incidence of zoster in patients with SLE was 32.5/1,000 patients per year. Patients who developed zoster had higher rates of lupus nephritis (P = 0.018) and positive anti-Sm antibody (P = 0.019). However, Fc gamma RIIa and Fc gamma RIIIa polymorphism and the HLA-DRB1 genotype did not influence herpes zoster occurrence. CONCLUSION: Systemic lupus erythematosus patients with lupus nephritis or anti-Sm antibody are at higher risk of herpes zoster. Fc gamma RIIa (H/R131), Fc gamma RIIIa (F/V176), and HLA-DRB1 genetic polymorphisms did not influence the occurrence of herpes zoster in these patients.
Biomarkers to indicate past exposure to radiation have not been entirely satisfactory. Using cDNA microarray hybridization to find new potential biomarkers, we identified highly expressed genes in human peripheral blood lymphocytes (PBLs) after irradiation 1 Gy ex vivo. The present set of radiation markers in PBLs was identified 12 h after radiation. A total of 44 genes were identified. However, when RT-PCR was performed with mRNA from the PBLs of five individuals, only four genes, including TRAIL receptor 2, DRAL (now known as FHL2), cyclin G, and cyclin protein gene, showed greater than 50% agreement between gene induction as detected by microarray analysis and by RT-PCR. When more than 32 donors were tested for the above four genes, greater than 85% agreement was obtained between gene induction measured by microarray analysis and by RT-PCR. There was a linear dose-response relationship between 0.5 and 4 Gy 12 h after irradiation; however, there was less linearity at later times. These results suggested that the relative expression levels of genes such as TRAIL receptor 2, FHL2, cyclin G, and cyclin protein gene in PBLs may provide estimates of radiation exposures.
The aim of our study was to develop a Korean rheumatic diseases-screening questionnaire. The questionnaire was constructed based on American College of Rheumatology criteria for rheumatic diseases and a connective tissue diseases screening questionnaire. Two groups of patients were selected and completed the questionnaire: (i) those with osteoarthritis (n=46), rheumatoid arthritis (n=52), systemic lupus erythematosus (n=50), scleroderma (n=8), polymyositis or dermatomyositis (n=7), Sjogren's disease (n=4), and mixed connective-tissue disease (n=9) as case subjects; and (ii) those with fibromyalgia (n=8) and general disease without evidence of any rheumatic disease (n=72) as controls. Laboratory results were analyzed for correlation with actual data using kappa (kappa) statistics. Test-retest reliability was performed in 12 patients, and showed strong agreement between the first and second interviews (kappa=0.91). The sensitivity of the questionnaire ranged from 77.8 to 100%, and specificity ranged from 68.8 to 95.0%. Negative predictive values were very high in the general population, from 98.4 to 99.99%. The kappa statistic for agreement between laboratory items was 0.22-0.56, except for rheumatoid factor, antinuclear antibody test, and muscle enzyme level. We have developed a simple and sensitive Korean rheumatic diseases-screening questionnaire for the epidemiologic study of rheumatic diseases in Korea.
PURPOSE: Sphingolipid metabolites, such as sphingosine and ceramide, are highly bioactive compounds and are involved in diverse cell processes, including cell-cell interaction, cell proliferation, differentiation, and apoptosis. However, the physiological roles of phytosphingosine are poorly understood. In this study, we report that phytosphingosine can potently induce apoptotic cell death in human cancer cells via caspase activation and caspase-independent cytochrome c release. EXPERIMENTAL DESIGN: Phytosphingosine-induced apoptosis was determined by Hoechst 33258 staining, flow cytometric analysis, and DNA fragmentation assay. Involvement of caspases was determined by immunoblot analysis and cell death detection assays after treatment with synthetic inhibitor z-Val-Ala-Asp-fluoromethyl ketone, z-DEVD-fmk, or z-IETD-fmk. Death receptor (DR) dependency was analyzed by examining expression of DRs (Fas, DR4, DR5, TNFR1, and R2), and interaction of Fas-associated death domain and caspase 8. Involvement of the mitochondria pathway was examined by monitoring of the mitochondria membrane potential, cytochrome c release, and Bax translocation. RESULTS: Phytosphingosine-treated cells displayed several features of apoptosis, including increase of sub-G(1) population, DNA fragmentation, and poly(ADP-ribose) polymerase cleavage. We observed that phytosphingosine cause activation of caspase 8 in a DR-independent fashion. Phytosphingosine also induced activation of caspase 9 and 3, loss of mitochondrial membrane potential, and the cytochrome c release from mitochondria. However, we failed to detect Bid cleavage. Moreover, caspase 8 inhibitor z-IETD-fmk did not affect phytosphingosine-induced cytochrome c release and caspase 9 activation, suggesting that phytosphingosine-induced cytochrome c release is caused by caspase 8-independent manner. Phytosphingosine induced mitochondrial translocation of Bax from the cytosol without changes in the protein levels of Bcl-2, Bcl-xL, and Bax. In addition, Bcl-2/Bax interaction was diminished after addition of phytosphingosine. CONCLUSION: These findings indicate that phytosphingosine induces apoptotic cell death in human cancer cells by direct activation of caspase 8, and by mitochondrial translocation of Bax and subsequent release of cytochrome c into cytoplasm, providing a potential mechanism for the anticancer activity of phytosphingosine.
It is well-known that p38 mitogen-activated protein kinase (p38MAPK) participates in cellular responses to mitogenic stimuli, environmental and genotoxic stresses, and apoptotic agents. Although there are several reports on p38MAPK in relation to cell growth and apoptosis, the exact mechanism of p38MAPK-mediated cell growth regulation remains obscure. Here, we examined possible roles of p38MAPK in the sodium arsenite-induced cell growth inhibition in NIH3T3 cells. Sodium arsenite induced transient cell growth delay with marked activation of p38MAPK. In addition, arsenite induced CDK inhibitor p21(CIP1/WAF1) and enhanced its binding to the CDK2, which resulted in inhibition of CDK2 activity. The levels of cyclin D1 expression and the CDK4 kinase activity were also significantly reduced. pRB was hypophosphorylated by sodium arsenite. SB203580, a specific inhibitor of p38MAPK, blocked arsenite-induced growth inhibition as well as the arsenite-induced p21(CIP1/WAF1) expression. Expression of dominant negative p38MAPK also blocked arsenite-induced p21(CIP1/WAF1) expression. Inhibited-CDK2 activity was also completely reversed by SB203580 or expression of dominant negative p38MAPK, while the decreased-cyclin D1 protein by the compound was not restored. These data demonstrate a possible link between the activation of p38MAPK and induction of p21(CIP1/WAF1), suggesting that the activation of p38MAPK is, at least in part, related to the cell growth inhibition by sodium arsenite.
This study was performed to define the clinical spectrum and disease manifestations of ankylosing spondylitis (AS) in a referral hospital setting. We identified the differences in clinical manifestations according to the sex, the age at onset, the presence of peripheral arthritis and the presence of HLA B27. A total 412 patients (357 males, 55 females) were recruited. Eighty-seven percent were men and 155 out of 412 patients (35%) were juvenile-onset. HLA B27 was detected in 385 patients (93%). Peripheral joint involvement was noted in 287 of total AS cases (juvenile- onset ankylosing spondylitis (JOAS), 82%; adult-onset ankylosing spondylitis (AOAS), 61%), and was more common than those reported in other studies. A greater portion of patients with JOAS had peripheral arthritis and peripheral enthesitis than the patients with AOAS. The patients with peripheral arthritis showed a younger age at onset and an increased tendency of having enthesitis and trauma history. The natural history of Korean AS appears largely similar to those seen in Europe and North America, except a few differences. JOAS was quite common and AS was about nine times more common in men than in women. In addition, the HLA B27 antigen frequency was 93%, which is higher than those reported in other studies.
Protein kinase C (PKC) has been widely implicated in regulation ofcell growth/cell cycle progression and apoptosis. However,the role of PKCdelta in radiosensitivity and cell cycle regulation remains unclear. Overexpression of PKCdelta increased Ca2+-independent PKC activity without altering other PKC isoforms (PKCalpha, -beta1, -epsilon, and -zeta), and extracellular regulated protein kinase (ERK) 1/2 activity was also increased in PKCdelta-specific manner. A clonogenic survival assay showed that PKCdelta-overexpressed cells had more radiosensitivity and pronounced induction of apoptosis than control cells. Flow cytometric analysis revealed that PKCdelta made the cells escape from radiation-induced G(2)-M arrest. Moreover, p53 and p21(Waf) induction by radiation were higher in PKCdelta-overexpressed cells than control cells, and PKCdelta-mediated apoptosis was reduced, when radiation-induced ERK1/2 activity was inhibited by PD98059. Furthermore, PKCdelta antisense and rottlerin, PKC inhibitor-abrogated PKCdelta-mediated radiosensitivity and reduced ERK1/2 activity to the control vector level. These results demonstrated that PKCdelta overexpression enhanced radiation-induced apoptosis and radiosensitivity via ERK1/2 activation, thereby abolishing the radiation-induced G(2)-M arrest and finally apoptosis.
The purpose of this study was to estimate predictive markers of intrinsic radiosensitivity in individuals who were exposed to occupational or environmental radiation. Throughout this process, the actual biohazard risks and base-line chromosome damage were evaluated in human population. Further studies were carried out to provide evidence for the existence of individual variations in age-dependent responses through micronuclei (MN) assay. Spontaneous frequencies not only vary greatly between individuals, but also working or living areas. It was shown that the increased level of spontaneous cell with MN was observed with increasing age. The relationship between radiosensitivity and the increased spontaneous level of MN may be in an inverse proportion. Ionizing radiation may be targeted mutagenic effects at the usual exposures of background levels that populations were exposed. Age and gender are the most important demographic variables in determining the MN index with frequencies in females, which were greater than those in males. The main life-style factors influencing the MN index in subjects were correlated significantly and positively with smoke. The results showed that an indicator of the genetic damaged rate in MN index in human populations significantly correlated with age, sex and life-style factors. So far, it is evident that with regard to the application of MN assay all future studies have to take into account the influence of age, gender, and life-style. In Conclusion, using micronuclei assay technique a large population can be easily monitored. This study illustrated that the MN assay may provide a high potential to ensure appropriate quality control and standard documentation protocol that can be used to monitor a large population exposed to radiation epidemiologically.
The detrimental effects of environmental pollutants on the health of the individual are generally accepted, although the mechanisms of these effects remain to be incompletely understood. In the present study, we examined the effects of B[a]P, 2-BP, phenol and TCDD on proinflammatory cytokine gene expression in mice spleen cells which were stimulated with anti-CD3. 10(-9)M TCDD increased IFNgamma and TNFalpha gene expression, but suppressed IL-1 gene expression. 10(-6)M phenol inhibited IL-1, IL-6 and TNFalpha gene expression, and 10(-6)M of 2-BP downregulated TNFalpha gene expression. However, 10(-6)M of B[a]P did not influence on IL-1, IL-6, IFNgamma and TNFalpha gene expression. These findings suggest that TCDD may impair the immune functions of mice by enhancing proinflammatory cytokines production, whereas phenol and 2-BP may impair the functions by inhibiting the production of these cytokines.