Biomedical subjects

Dong-Wook Kim

Publications and source records attributed to Dong-Wook Kim.

At least 55 records · Page 3Linked to original sources

PubMed2003

Characterization of Grp1p, a novel cis-Golgi matrix protein.

A high copy suppressor screen with sec34-2, a temperature-sensitive mutant defective in the late stages of ER to Golgi transport, has resulted in the identification of a novel gene called GRP1 (also called RUD3). GRP1 encodes a hydrophilic yeast protein related to the mammalian Golgi matrix protein golgin-160. A large portion of the protein is predicted to form a coiled-coil structure. Although GRP1 is not essential for growth, the loss of Grp1p results in a growth defect at high temperature. GRP1 genetically interacts with several genes involved in vesicle targeting/fusion stages of ER to Golgi transport. Despite these interactions, pulse chase analysis using Grp1p-depleted cells did not reveal a significant delay in the transit of the vacuolar protease carboxypeptidase Y. Grp1p-depleted cells efficiently secreted invertase which was underglycosylated, suggesting some disturbance of Golgi function. Grp1p-GFP predominantly colocalizes with the cis-Golgi marker Och1p. Despite lacking a signal peptide and a significant stretch of hydrophobic amino acids, Grp1p pellets with membranes. It is extracted with 1M NaCl or 0.1M Na(2)CO(3) (pH 11.0), but is surprisingly insoluble in 1% Triton X-100. Grp1p does not recycle to the ER when forward transport is blocked and a cis-Golgi marker (Och1p-HA), but not a trans-Golgi marker (Chs5p-HA), became dispersed in grp1 Delta cells after 1.5h incubation at 38.5 degrees C. Together, these data suggest that Grp1p is a novel matrix protein that is involved in the structural organization of the cis-Golgi.

Carrier Proteins↗

PubMed2003

Polymorphisms of IL-1B, IL-1RN, IL-2, IL-4, IL-6, IL-10, and IFN-gamma genes in the Korean population.

Cytokines play a crucial role in regulating the immune and inflammatory responses. The collective influence of several cytokines can regulate immune responses as complex as those underlying allograft rejections or autoimmune diseases. Polymorphisms in the regulatory regions of the cytokine genes may influence their expression. Therefore, the polymorphisms of cytokine genes are potentially important as genetic predictors of the disease susceptibility or clinical outcome. In 311 unrelated healthy Korean individuals, we investigated the polymorphisms of cytokine genes (interleukin-1 [IL-1], IL-2, IL-4, IL-6, IL-10, and interferon-gamma [IFN-gamma]), which had been previously reported to be associated with a number of immune diseases, transplant complications, and direct or indirect influences on the level of expression and production. And we also compared the results to those published for other populations. The genotype distributions were consistent with the assumption of the Hardy-Weinberg equilibrium, with the exceptions of IL-1B +3954 and IL-6-174 polymorphisms. The polymorphisms examined in this study were almost similar to that observed in Asian populations. There were significant differences of the polymorphisms, except for IL-4 receptor alpha +1902, between Korean and other populations. Comparing the alleles associated with higher level of expression and production, IL-1B +3954*T, IL-2-330*G, and IL-4-590*T alleles were significantly higher, and IL-1RN*A2, IL-10-1082*G, and IFN-gamma*2 alleles were lower in Koreans than other populations. Especially in IL-6 promoter -174 polymorphism, we found only the G allele associated with higher plasma IL-6 levels. In haplotype analysis of IL-10 promoter polymorphisms, the GCC haplotype, associated with higher expression of IL-10, was significantly lower in Koreans. These results may be helpful for understanding transplant-related complications, immune or autoimmune diseases, and malignant diseases in the Korean population.

Gene Frequency↗

PubMed2003

Inhibitory effect of methanol extract of Euonymus alatus on matrix metalloproteinase-9.

Various extracts prepared from stems of Euonymus alatus were tested for cytotoxic activity on human hepatocellular carcinoma cell line, Hep3B cells using the XTT assay method. Also, the extracts were investigated the inhibitory effects on matrix metalloproteinase (MMP)-9 activity using gelatin zymography. The methanol extract, hexane and ethyl acetate fraction exhibited weak cytotoxic activity (IC(50) of >100 microg/ml). However, butanol (IC(50)=65 microg/ml) and chloroform (IC(50)=85 microg/ml) fraction exhibited strongly cytotoxic activity. Gelatin zymography showed that the Hep3B cells secreted matrix metalloproteinase (MMP), probably including MMP-9, which may be involved in tumor cell invasion and metastasis. The butanol fraction showed stronger inhibitory effect of proteolytic activity than other fractions. Also, the butanol fraction was able to decrease the proteolytic activity of MMP-9 in a concentration-dependent manner on zymography. These results suggest that the butanol fraction from E. alatus has highly inhibitory effect on MMP-9 in comparatively low cytotoxicity.

Antineoplastic Agents↗

PubMed2003

A multiplex polymerase chain reaction for a differential diagnosis of Plasmodium falciparum and Plasmodium vivax.

A multiplex PCR was designed for the differential diagnosis of the two parasite species by targeting the 18S rRNA gene with a set of primer combinations, amplifying DNA fragments of 1451-bp and 833-bp for P. falciparum and P. vivax, respectively. The sensitivity of this PCR test was high, as minimal as 0.1 parasite per one microliter of blood sample and a minimum of four copies of the target gene could be detected. For the diagnosis of mixed infection of two Plasmodium spp., there were no apparent competition or cross-reaction between the majority and minority Plasmodium species. The multiplex PCR was evaluated on 210 clinical samples and 60 normal controls. The PCR test yielded highly concordant results with microscopic examination, with the only one exception of a mixed (P. falciparum plus P. vivax) infection case, which was diagnosed as a single infection of P. falciparum by microscopy. We propose that the multiplex PCR is a sensitive, specific, and rapid tool that can serve as a useful differential diagnostic tool for detecting P. falciparum and P. vivax.

Animals↗

PubMed2003

Risk factors for adults with Philadelphia-chromosome-positive acute lymphoblastic leukaemia in remission treated with allogeneic bone marrow transplantation: the potential of real-time quantitative reverse-transcription polymerase chain reaction.

The aim of this study was to evaluate the outcomes for Philadelphia-chromosome-positive acute lymphoblastic leukaemia (Ph+ ALL) patients in remission treated with allogeneic bone marrow transplantation (BMT). Twenty-three adults were entered onto this study. The 2-year probabilities of relapse and disease-free survival (DFS) were 39.4 +/- 11.6% and 43.5 +/- 10.3% respectively. The presence of chronic graft-versus-host disease (GVHD) was found to be an independent predictive factor affecting lower relapse and DFS. To monitor the BCR-ABL transcript, we also analysed 48 bone marrow samples of eight patients using real-time quantitative reverse-transcription polymerase chain reaction (RT-PCR). The kinetics of the BCR-ABL transcript correlated well with the patients' clinical course. In six patients who were in continuous remission after BMT, a rapid decrease in BCR-ABL copy number to the PCR-negative status was observed after the development of chronic GVHD. Meanwhile, routine bone marrow examination of two patients showed PCR positivity with a 3 or 4-log increase of BCR-ABL copy number and subsequent haematological relapse, which occurred 2 and 4 months later respectively. Although our data should be interpreted cautiously, the presence of chronic GVHD may reduce the risk of relapse in Ph+ ALL. Real-time quantitative RT-PCR appears to be a useful test for BCR-ABL transcript monitoring.

Adult↗

PubMed2003

An estimation method of hemolysis within an axial flow blood pump by computational fluid dynamics analysis.

Evaluation of hemolysis within a blood pump on a computer is useful for developing rotary blood pumps. The flow fields in the axial flow blood pump were analyzed using computational fluid dynamics (CFD). A blood damage index was calculated based on the changes in shear stress with time along 937 streamlines. Hemolysis of the pumps was measured using bovine blood. A good correlation between the computed and measured hemolysis results was observed. CFD analysis is useful for estimating hemolysis of rotary blood pumps on a computer.

Animals↗

PubMed2003

Development of a magnetic fluid shaft seal for an axial-flow blood pump.

A rotating impeller in a rotary blood pump requires a supporting system in blood, such as a pivot bearing or magnetic suspension. To solve potential problems such as abrasive wear and complexity of a supporting system, a magnetic fluid seal was developed for use in an axial-flow blood pump. Sealing pressures at motor speeds of up to 8,000 rpm were measured with the seal immersed in water or bovine blood. The sealing pressure was about 200 mm Hg in water and blood. The calculated theoretical sealing pressure was about 230 mm Hg. The seal remained perfect for 743 days in a static condition and for 180+ days (ongoing test) at a motor speed of 7,000 rpm. Results of measurement of cell growth activity indicated that the magnetic fluid has no negative cytological effects. The specially designed magnetic fluid shaft seal is useful for an axial-flow blood pump.

Animals↗

PubMed2003

Computational fluid dynamics analysis of an intra-cardiac axial flow pump.

A low rate of hemolysis is an important factor for the development of a rotary blood pump. It is, however, difficult to identify the areas where hemolysis occurs. Computational fluid dynamics (CFD) analysis enables the engineer to predict hemolysis on a computer. In this study, fluid dynamics throughout intracardiac axial flow pumps with different designs were analyzed three-dimensionally using CFD software. The computed pressure-flow characteristics of the pump were in good agreement with the measurements. The Reynolds shear stress was computed along particle trace lines. Hemolysis was estimated on the basis of shear stress (tau) and its exposure time (Deltat): dHb/Hb = 3.62 x 10(-7)(tau)(i)(2.416) x Delta(t)(i)(0.785). Particle damage increased with time along the particle trace lines. Hemolysis of each of the pumps was measured in vitro. The computed hemolysis values were in good agreement with the experimental results. CFD is a useful tool for developing a rotary blood pump.

Computational Biology↗

PubMed2003

Effects of traditional Chinese formulations on rat carotid artery injured by balloon endothelial denudation.

We examined the inhibitory effects of traditional Chinese formulations (TCFs: Kampo formulation in Japanese) on intimal thickening of the carotid artery injured by balloon endothelial denudation in rats. Among the eight TCFs examined oren-gedoku-to (huanglian-jiedu-tang in Chinese), choto-san (diao-teng-san), saiko-ka-ryukotsu-borei-to (chaihujia-longgu-muli-tang) and dai-joki-to (da-cheng-qi-tang) significantly inhibited the intimal thickening 7 days after denudation. These four TCFs also inhibited proliferation of vascular smooth muscle cells (VSMC), which may play a central role in the development of restenosis after balloon endothelial denudation. The present results suggest that further evaluation of these four TCFs as inhibitors of VSMC proliferation to prevent arteriosclerosis is warranted.

Animals↗

PubMed2002

Regulation and the role of Cu,Zn-containing superoxide dismutase in cell cycle progression of Schizosaccharomyces pombe.

Regulation and the role of the sod1+ gene encoding CuZnSOD were investigated in fission yeast Schizosaccharomyces pombe. The amount of sod1+ mRNA decreased in the stationary phase, consistent with the decrease in enzyme activity. The transcript increased by treatment with oxidants such as H(2)O(2) and menadione (MD). Induction by H(2)O(2) was rapid and transient, being dependent on Wis1-Spc1-Atf1 pathway of signal transduction, whereas induction by MD was slow and sustained longer, being independent of Wis1 pathway. Wis1 and Spc1 also turned out to down-regulate sod1+ gene at the stationary phase. Tetrad analysis following sod1+ gene disruption revealed that the sod1Delta cells were not viable, even on rich media. Repression of the sod1+ gene expression by thiamine through nmt1 promoter resulted in the arrest of cell cycle progression following S phase, possibly between G(2) and cytokinesis. The current and previous observations that the viability of Schizosaccharomyces pombe cells, unlike Saccharomyces cerevisiae, critically depends on the action of oxidative defense enzymes in the cytosol, such as CuZnSOD and glutathione reductase, suggest that S. pombe can serve as a good model system to study the effect of oxidative stress on cell proliferation.

Base Sequence↗

PubMed2002

Detection of the BCR-ABL gene by interphase fluorescence in situ hybridization (iFISH) in chronic myelogenous leukemia patients after hemopoietic stem cell transplantation: the feasibility of iFISH monitoring of therapeutic response in peripheral blood.

The detection of the Philadelphia (Ph) translocation has been accomplished primarily by cytogenetic analysis and reverse transcriptase polymerase chain reaction (RT-PCR). RT-PCR is highly sensitive (1/10(4)-10(6)) but not quantitatively reliable and is thus unsuitable for the monitoring of Ph-positive cells during therapy. Interphase fluorescence in situ hybridization (iFISH) allows analysis of a large number of cells (> 500) in a timely and efficiently quantitative manner. We obtained 118 peripheral blood (PB) and 127 bone marrow (BM) samples from 75 adult chronic myelogenous leukemia (CML) patients undergoing stem cell transplantation. We simultaneously performed nested RT-PCR and iFISH for all samples. False-positive cells were detected in 2.48% +/- 0.93% (mean +/- SD) of PB samples and 2.75% +/- 0.83% of BM samples. The iFISH results for PB and BM ranged from 1.4% to 92.8% and 1.0% to 93.8%, respectively. Correlation analysis of iFISH results for PB versus BM samples showed a strong relation (r = .993). A significant correlation (P < .05) was also found between iFISH and first-round RT-PCR. The sensitivity of BCR-ABL iFISH was similar to that of first-round RT-PCR, and iFISH results for PB and BM were also well correlated. Thus, iFISH analysis of PB and/or BM samples may be more clinically reliable than RT-PCR in the quantitative monitoring of BCR-ABL fusion in CML after transplantation.

Blood Cells↗

PubMed2002

Inhibitory effect of a Korean traditional medicine, Honghwain-Jahage (water extracts of Carthamus tinctorius L. seed and Hominis placenta) on interleukin-1-mediated bone resorption.

A Korean herbal formulation, Honghwain-Jahage (HJ), which is comprised of a herb of Carthamus tinctorius L. seed and Hominis Placenta, was investigated for inhibiting effects on IL-1 beta-stimulated bone resorption in the fetal mouse bone culture system. Results of in vitro cytotoxicities showed that HJ extracts have no any cytotoxicities in concentrations of 1-200 microg/ml on the cultured osteoblast cells derived from mouse calvarial bone explants. Cell viability was not significantly affected by treatment with the indicated concentration of the extracts. The HJ extracts were shown to have inhibitory effects against the synthesis of PGE(2). We also examined the effect of the pretreatment with various concentrations of the HJ extracts then treated by the PGE(2)-induction agents. Pretreatment of the HJ extracts for 1 h, which by itself had little effect on cell survival, reduced the synthesis of PGE(2). Furthermore, the HJ extracts were shown to have protective effects against plasminogen dependent fibrinolysis induced by IL-1 beta. Pretreatment of the HJ extracts for 1 h did not enhance the plasminogen dependent fibrinolysis. Finally, co-treatment of HJ with calcitonin showed significant inhibitory activity on the IL-1 beta-stimulated bone resorption. From these results, it was found that HJ extracts inhibited IL-1 beta-induced bone resorption.

Animals↗

PubMed2002

Comprehensive comparison of FISH, RT-PCR, and RQ-PCR for monitoring the BCR-ABL gene after hematopoietic stem cell transplantation in CML.

The reverse transcriptase-polymerase chain reaction (RT-PCR) was compared with fluorescence in situ hybridization (FISH) and real-time quantitative RT-PCR (RQ-PCR) for minimal residual disease (MRD) monitoring in 266 post-transplant bone marrow samples from 78 patients with chronic myelogenous leukemia (CML). The sensitivities of FISH to BCR-ABL positive samples determined by first-round (1st) RT-PCR, second-round (2nd) RT-PCR, and RQ-PCR were 64.2%, 25.8%, and 20.7%, respectively. The BCR-ABL/ABL ratio by RQ-PCR had a mean of 0.000 13 in the 1st RT-PCR-negative samples and 1.42 in the 1st RT-PCR-positive samples (P<0.001), and means of 0.000 39 and 0.51 in the 2nd RT-PCR-negative and -positive samples (P< 0.001). The mean ratios of BCR-ABL/ABL by RQ-PCR were significantly different in N/N (1st/2nd RT-PCR) or N/P and P/P (P<0.001), but not in N/N and N/P, which showed that the discriminative power of RQ-PCR is confined to the 1st RT-PCR level. In this respect, monitoring of the 1st RT-PCR might be useful for estimating normalized BCR-ABL levels after transplantation. Nested RT-PCR was of limited use, as RQ-PCR quantified the BCR-ABL transcripts in 60 (91%) of 66 samples determined to be negative by 2nd RT-PCR. FISH was significantly correlated with RQ-PCR in FISH-positive samples (n=24, r=0.79, P=0.001). An increase of FISH preceded that of RQ-PCR in a few cases with molecular relapse. By analyzing a large number of samples post-transplant, we found that RQ-PCR might be the most useful assay for MRD monitoring; however, FISH and RT-PCR were found to be useful complementary tools.

Bone Marrow↗

PubMed2002

Influence of karyotype on outcome of allogeneic bone marrow transplantation for adults with precursor B-lineage acute lymphoblastic leukaemia in first or second remission.

The prognostic relevance of karyotype has been established in adult acute lymphoblastic leukaemia (ALL) patients treated with chemotherapy but not definitively evaluated in an allogeneic bone marrow transplantation (BMT) setting. To determine the factors affecting the outcome of allogeneic BMT for adults with precursor B-lineage ALL in first or second complete remission (CR), a total of 41 consecutive patients with a successful karyotype were enrolled in this study. There were 21 men and 20 women with a median age of 27 (15-43) years. The distribution of French-American-British (FAB) subtypes was as follows: L1 (n = 26), L2 (n = 15). Unfavourable karyotypes (n = 12) were defined as Ph+ or t(4;11). Disease status at the time of transplant was first CR (n = 35) or second CR (n = 6). With a median follow-up of 36 months, the 3-year probabilities of relapse and disease-free survival (DFS) were 36.3 +/- 8.4% and 57.3 +/- 8.4% respectively. Potential variables predicting worse relapse and DFS were FAB subtype (L2), extramedullary involvement, pre-BMT status (second CR), unfavourable karyotype and type of graft-versus-host disease (GVHD). Further multivariate analysis showed that karyotype and pre-BMT status were independently associated with relapse and DFS. In addition, chronic GVHD was found to be significantly associated with a lower relapse rate.

Adolescent↗

PubMed2002

Genetic engineering of mouse embryonic stem cells by Nurr1 enhances differentiation and maturation into dopaminergic neurons.

Nurr1 is a transcription factor critical for the development of midbrain dopaminergic (DA) neurons. This study modified mouse embryonic stem (ES) cells to constitutively express Nurr1 under the elongation factor-1alpha promoter. The Nurr1-expression in ES cells lead to up-regulation of all DA neuronal markers tested, resulting in about a 4- to 5-fold increase in the proportion of DA neurons. In contrast, other neuronal and glial markers were not significantly changed by Nurr1 expression. It was also observed that there was an additional 4-fold increase in the number of DA neurons in Nurr1-expressing clones following treatment with Shh, FGF8 and ascorbic acid. Several lines of evidence suggest that these neurons may represent midbrain DA neuronal phenotypes; firstly, they coexpress midbrain DA markers such as aromatic L-amino acid decarboxylase, calretinin, and dopamine transporter, in addition to tyrosine hydroxylase and secondly, they do not coexpress other neurotransmitters such as GABA or serotonin. Finally, consistent with an increased number of DA neurons, the Nurr1 transduction enhanced the ability of these neurons to produce and release DA in response to membrane depolarization. This study demonstrates an efficient genetic manipulation of ES cells that facilitates differentiation to midbrain DA neurons, and it will serve as a framework of genetic engineering of ES cells by key transcription factor to regulate their cell fate.

Animals↗

PubMed2002

Preventive effects of a traditional Chinese formulation, Chaihu-jia-Longgu-Muli-tang, on intimal thickening of carotid artery injured by balloon endothelial denudation in rats.

We report here that the traditional Chinese formulation, Chaihu-jia-Longgu-Muli-tang (CLM), significantly inhibited the increase in intimal thickening in rat carotid artery injured by balloon endothelial denudation, which mimics many aspects of restenosis after percutaneous coronary intervention (PCI) in humans. CLM, Saiko-ka-Ryukotsu-Borei-to in Japanese, is commonly prescribed for symptoms accompanying hypertension and atherosclerosis in Japanese Kampo medical care. CLM administered orally 1 week before and 1, 4 and 8 weeks after balloon injury inhibited the increase in intimal area, intimal/medial ratio and stenosis ratio. To our knowledge, this is the first report demonstrating inhibitory effects of a traditional Chinese formulation on intimal thickening of carotid artery after balloon injury. It is worth noting that CLM maintained its inhibitory effect up to 8 weeks after balloon injury. The reduction in intimal thickening by CLM could have resulted from inhibition of intimal smooth muscle cell proliferation, which was assessed by immuno-histochemical analysis using monoclonal antibody against proliferating cell nuclear antigen. Therefore, CLM may be a favourable candidate for prevention of restenosis after PCI. Moreover CLM may have a therapeutic value in the prevention of atherosclerosis, because restenosis after PCI is considered to be an accelerated atherosclerosis.

Angioplasty, Balloon, Coronary↗

PubMed2002

Three-dimensional approach to stem cell therapy.

Recent progress in stem cell research is opening a new hope for cell therapy in regenerative medicine. Two breakthroughs were made in the stem cell era, one, new discoveries in multi-potentiality of adult stem cells beyond the traditionally appreciated extent, and the other, establishment of pluripotent stem cell from human embryo. In addition to the newly identified multi-potentiality of adult stem cells, their ability to be trans-differentiated toward other tissue types (stem cell plasticity) as well as to migrate toward the site of tissue damage make adult stem cells particularly attractive choice for stem cell based therapy. Stem cell therapy for organ regeneration, therefore, could be approached from three distinct dimensions: first, direct differentiation of multi-potent stem cells toward desired tissue types; secondly, regeneration of specific tissues through in vivo stem cell plasticity, and lastly, by tissue-specific stem cells from many types of organs. While each approach in stem cell therapy poses distinctive limitations for their successful clinical applications, understanding regulatory mechanisms of stem cell self-renewal and their in vivo engraftment will mostly extend their medical efficacy of stem cell based therapy.

Animals↗

PubMed2002

Two cases of disseminated mucormycosis in patients following allogeneic bone marrow transplantation.

We describe two cases of disseminated mucormycosis following allogeneic bone marrow transplantation (BMT). Both patients were suffering from chronic graft-ver-sus-host disease (GVHD) and treated with prolonged administration of corticosteroid. In both cases, the initial symptoms were high fever and left flank pain. Involved organs were the spleen, right kidney and the right lung in one case, and the spleen and the brain in the other. The diagnosis was confirmed by pathology after splenectomy. One patient, in whom the immunosuppressants could be discontinued, was treated with prolonged conventional and liposomal amphotericin B and 5-fluorocytosine. The other, in whom the immunosuppressants could not be discontinued due to extensive GVHD, was unresponsive to amphotericin B, and eventually died from the fungal infection. Although mucormycosis, especially the disseminated form thereof is infrequent, it should be considered in high-risk patients because early diagnosis and timely therapy combining antifungal drug or surgery and reduction of immunosuppression appear to improve the prognosis.

Adult↗