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H K Park

Publications and source records attributed to H K Park.

At least 19 recordsLinked to original sources
PubMed2006

Measurement of the asymmetry in the decay Omega+-->LamdaKappa+-->rhopi+Kappa+.

The asymmetry in the rho angular distribution in the sequential decay Omega+-->LamdaKappa+-->rhopi+Kappa+. has been measured to be alphaOmegaalphaLamda=[+1.16+/-0.18(stat)+/-0.17(syst)]x10(-2) using 1.89x10(6) unpolarized Omega+ decays recorded by the HyperCP (E871) experiment at Fermilab. Using the known value of alphaLamda, and assuming that alphaLamda=-alphaLamda, alphaOmega=[-1.81+/-0.28(stat)+/-0.26(syst)]x10(-2). A comparison between this measurement of alphaOmegaalphaLamda and recent measurements of alphaOmegaalphaLamda made by HyperCP shows no evidence of a violation of CP symmetry.

Journal Article↗
PubMed2006

Observation of high-field-side crash and heat transfer during sawtooth oscillation in magnetically confined plasmas.

High resolution (temporal and spatial), two-dimensional images of electron temperature fluctuations during sawtooth oscillations were employed to study the crash process and heat transfer in magnetically confined toroidal plasmas. The combination of kink and local pressure driven instabilities leads to a small poloidally localized puncture in the magnetic surface at both the low and the high field sides of the poloidal plane. This observation closely resembles the "fingering event" of the ballooning mode model with the high- mode only predicted at the low field side.

Journal Article↗
PubMed2006

Comparison study of 2D images of temperature fluctuations during sawtooth oscillation with theoretical models.

High temporal and spatial resolution two-dimensional (2D) images of electron temperature fluctuations were employed to study the sawtooth oscillation in the Toroidal Experiment for Technically Oriented Research tokamak plasmas. The 2D images are directly compared with the expected 2D patterns of the plasma pressure (or electron temperature) from various theoretical models. The observed experimental 2D images are only partially in agreement with the expected patterns from each model: The image of the initial reconnection process is similar to that of the ballooning mode model. The intermediate and final stages of the reconnection process resemble those of the full reconnection model. The time evolution of the images of the hot spot or island is partially consistent to those from the full reconnection model but is not consistent with those from the quasi-interchange model.

Journal Article↗
PubMed2005

Search for the lepton-number-violating decay Xi(-)-->pmu(-)mu(-).

A sensitive search for the lepton-number-violating decay Xi(-)-->pmu(-)mu(-) has been performed using a sample of approximately 10(9) Xi(-) hyperons produced in 800 GeV/c p-Cu collisions. We obtain B(Xi(-)-->pmu(-)mu(-))<4.0x10(-8) at 90% confidence, improving on the best previous limit by 4 orders of magnitude.

Journal Article↗
PubMed2005

Search for DeltaS = 2 nonleptonic hyperon decays.

A sensitive search for the rare decays Omega(-)--> Lambdapi(-) and Xi(0)--> ppi(-) has been performed using data from the 1997 run of the HyperCP (Fermilab E871) experiment. Limits on other such processes do not exclude the possibility of observable rates for |DeltaS| = 2 nonleptonic hyperon decays, provided the decays occur through parity-odd operators. We obtain the branching-fraction limits B(Omega(-)-->Lambdapi(-)) < 2.9 x 10(-6) and B(Xi(0)--> ppi(-)) < 8.2 x 10(-6), both at 90% confidence level.

Journal Article↗
PubMed2005

Evidence for the decay sigma+ --> pmu+ mu-.

We report the first evidence for the decay Sigma(+)-->pmu(+)mu(-) from data taken by the HyperCP (E871) experiment at Fermilab. Based on three observed events, the branching ratio is B(Sigma(+)-->pmu(+)mu(-))=[8.6(+6.6)(-5.4)(stat)+/-5.5(syst)]x10(-8). The narrow range of dimuon masses may indicate that the decay proceeds via a neutral intermediate state, Sigma(+)-->pP(0),P0-->mu(+)mu(-) with a P0 mass of 214.3+/-0.5 MeV/c(2) and branching ratio B(Sigma(+)-->pP(0),P0-->mu(+)mu(-))=[3.1(+2.4)(-1.9)(stat)+/-1.5(syst)]x10(-8).

Journal Article↗
PubMed2005

A 37-year-old spinal cord-injured female patient, transplanted of multipotent stem cells from human UC blood, with improved sensory perception and mobility, both functionally and morphologically: a case study.

HLA-matched UC blood-derived multipotent stem cells were directly transplanted into the injured spinal cord site of a 37-year-old female patient suffering from spinal cord injury (SPI). In this case, human cord blood (UCB)-derived multipotent stem cells improved sensory perception and movement in the SPI patient's hips and thighs within 41 days of cell transplantation. CT and MRI results also showed regeneration of the spinal cord at the injured site and some of the cauda equina below it. Therefore, it is suggested that UCB multipotent stem cell transplantation could be a good treatment method for SPI patients.

Adult↗
PubMed2004

Search for CP violation in charged-Xi and Lambda hyperon decays.

We have compared the p and p angular distributions in 117 x 10(6) Xi- -->Lambdapi- -->ppi-pi- and 41 x 10(6) Xi+ -->Lambda pi+ -->p pi+pi+ decays using a subset of the data from the HyperCP experiment (E871) at Fermilab. We find no evidence of CP violation, with the direct-CP-violating parameter AXiLambda identical with (alphaXialphaLambda-alpha Xialpha Lambda)/(alphaXialphaLambda+alphaXialphaLambda)=[0.0+/-5.1(stat)+/-4.4(syst)] x 10(-4).

Journal Article↗
PubMed2004

Effects of Paeonia lactiflora root extracts on the secretions of monocyte chemotactic protein-1 and -3 in human nasal fibroblasts.

In the field of Oriental medicine, the root of Paeonia lactiflora (Paeoniae Radix) has been prescribed usually to treat the common cold, and it was thought to alleviate upper respiratory infection or nasal inflammation. Monocyte chemotactic proteins (MCP)-1 and MCP-3 are known as the most potent chemokines to mediate allergic inflammation. The object of the study was to investigate the effect of Paeoniae Radix on the release of the chemokines such as MCP-1 and MCP-3. To detect the secretion of MCPs, an enzyme-linked immunosorbent assay was performed for human nasal mucosal fibroblasts after stimulation with several cytokines such as tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) and interleukin-1beta (IL-1beta). The secretion of MCP-1 was increased after stimulation with TNF-alpha or IL-1beta treatment. Co-treatment of TNF-alpha and IFN-gamma, or IL-1beta and IFN-gamma increased the secretion of MCP-1 and MCP-3. Paeoniae Radix was tested with inflammatory cytokines, and the results showed that the Paeoniae Radix significantly decreased the secretion of MCP-1 and MCP-3. In our study, Paeoniae Radix may play an important role in nasal inflammation with a modulation of MCP-1 and MCP-3.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2004

Attenuation of iNOS mRNA exacerbates hypoperfusion and upregulates endothelin-1 expression in hippocampus and cortex after brain trauma.

Nitric oxide (NO, a vasodilator) and endothelin-1 (ET-1, a powerful vasoconstrictor) participate in the regulation of brain's microcirculation influencing each other's expression and synthesis. Following injury to the brain, NO is derived largely from the inducible form of nitric oxide synthase (iNOS). We used Marmarou's model of traumatic brain injury (TBI) to study the cerebral blood flow and expression (mRNA) of ET-1 in rats that were pretreated with antisense iNOS oligodeoxynucleotides (ODNs). Intracerebroventricular application of iNOS ODNs resulted in reduced synthesis of iNOS as detected by Western blot analysis. The cerebral blood flow (measured by laser Doppler flowmetry), generally decreased after TBI, was further markedly reduced in the treated animals and remained at low levels up to 48 h post-TBI. The expression of ET-1 (detected by in situ hybridization in cortex and hippocampus) was increased 2-3-fold following TBI alone and this increase reached 5-6-fold in animals pretreated with antisense iNOS ODNs. The results indicate that most likely, NO, generated primarily by iNOS, suppresses ET-1 production and that a decrease of NO results in upregulation of ET-1 via transcriptional and translational mechanisms. Increased availability of ET-1 at the vascular bed and the neuropil may contribute to the altered microvascular reactivity and reduced perfusion of the brain following TBI.

Animals↗
PubMed2004

Impact of IL-1 receptor antagonist gene polymorphism on schizophrenia and bipolar disorder.

OBJECTIVES: Variable levels of cytokines were observed in patients with schizophrenia and bipolar disorder, and an especially high level of interleukin-1 (IL-1) was detected in schizophrenia patients. It is known that IL-1 receptor antagonist (IL-1RA) binds to IL-1 receptors and inhibits the receptor binding of IL-1alpha and IL-1beta. METHODS: In this study, the association between the variable number of tandem repeats polymorphism of the IL-1RA gene and schizophrenia (n=269) and bipolar disorder (n=83) was investigated. RESULTS: The genotype distribution and allele frequency were significantly different between schizophrenic patients and the control group (P<0.05); however, there were no prominent differences between bipolar patients and the control group. The carriage rate for the IL1RN*2 allele was associated with higher risk of schizophrenia (odds ratio=2.24). CONCLUSIONS: This study indicates that IL-1RA could be a candidate gene for susceptibility to schizophrenia.

Adult↗
PubMed2003

Successive double high-dose chemotherapy with peripheral blood stem cell rescue collected during a single leukapheresis round in patients with high-risk pediatric solid tumors: a pilot study in a single center.

In total, 18 of 26 double high-dose chemotherapies (HDCT) in pediatric solid tumors were rescued with peripheral blood stem cells collected during a single leukapheresis round (single-harvest group, SHG). In the remaining eight HDCT, additional leukapheresis were necessary after the first HDCT (HDCT1) to rescue the second HDCT (HDCT2) (double-harvest group, DHG). Stem cell collection after HDCT1 was inefficient and delayed in patients who had received prior chemotherapy before HDCT1. The interval between HDCT1 and HDCT2 was shorter in SHG than in DHG (median 62.5 days vs 178.5 days, P-value=0.002). Hematologic recovery in HDCT2 was delayed compared to HDCT1. However, there was no difference in hematologic recovery between SHG and DHG. A high rate of treatment-related mortality (TRM) was recorded during HDCT2, but there was no evidence that the shorter interval caused a higher rate of TRM (P-value=0.454). The probability of disease-free survival at 2 years after HDCT2 in the SHG and DHG were 66.7 and 25.0%, respectively (P-value=0.031). Therefore, to administer the second HDCT earlier in double HDCT, and thus to improve the survival of patients with high-risk solid tumors, the single-harvest approach is recommended rather than the double-harvest approach.

Adolescent↗
PubMed2002

Observation of the decay K- --> pi(-)mu(+)mu(-) and measurements of the branching ratios for K+/- --> pi(+/-)mu(+)mu(-).

Using data collected with the HyperCP (E871) spectrometer during the 1997 fixed-target run at Fermilab, we report the first observation of the decay K--->pi(-)mu(+)mu(-) and new measurements of the branching ratios for K+/--->pi(+/-)mu(+)mu(-). By combining the branching ratios for the decays K+-->pi(+)mu(+)mu(-) and K--->pi(-)mu(+)mu(-), we measure Gamma(K+/--->pi(+/-)mu(+)mu(-))/Gamma(K+/--->all) = (9.8+/-1.0+/-0.5)x10(-8). The CP asymmetry between the rates of the two decay modes is [Gamma(K+-->pi(+)mu(+)mu(-))-Gamma(K--->pi(-)mu(+)mu(-))]/[Gamma(K+-->pi(+)mu(+)mu(-))+Gamma(K--->pi(-)mu(+)mu(-))] = -0.02+/-0.11+/-0.04.

Journal Article↗
PubMed2002

Respiratory syncytial virus infection induces matrix metalloproteinase-9 expression in epithelial cells.

Increased gelatinolytic activity was observed in respiratory syncytial virus (RSV)-infected HEp-2 cells by using zymography. The anti-matrix metalloproteinase-9 (MMP-9) antibody specifically reduced the gelatinolytic activity suggesting that the increased gelatinolytic activity was due to the MMP-9. It was also supported by the results from immunofluorescent staining, treatment of MMP inhibitors, and RSV infection of the cell clones that were transfected with plasmids to express more MMP-9 and tissue type inhibitor of metalloproteinase-1 (TIMP-1). The gelatinolytic activity of extracellular MMP-9 in RSV-infected HEp-2 cells increased 1.5 +/- 0.2 fold compared with the control (p < 0.01). Cell surface MMP-9 expression was also clearly detected by immunofluorescent staining. Treatment with 1,10-phenanthroline (0.05 mM), ethylenediamine-tetraacetate (EDTA) (1.5 mM), and penta-O-galloyl-beta-D-glucose (PGG) (3.3 microM) inhibited RSV multiplication as well as syncytia formation. Furthermore, the average syncytia size increased when the cells expressing more MMP-9 were infected by RSV. In contrast, syncytia formation was inhibited in the cells manipulated to express TIMP-1. Thus, this study concludes that although RSV infection induces MMP-9, which can enhance the syncytia formation leading to RSV multiplication and spread it can be inhibited by MMP inhibitors.

Epithelial Cells↗
PubMed2002

(AC)(n) polymorphism of aldose reductase gene and diabetic microvascular complications in type 2 diabetes mellitus.

Recent studies suggest that the gene encoding aldose reductase, the enzyme that converts glucose to sorbitol, may confer susceptibility to microvascular disease. The aim of this study therefore, was to investigate the relationship between the aldose reductase gene and type 2 diabetic microvascular complications such as diabetic nephropathy and retinopathy. DNA from 127 Korean patients with type 2 diabetes was typed for an (AC)(n) dinucleotide repeat polymorphic marker at the 5'-end of the aldose reductase gene using polymerase chain reaction. No significant difference in the frequency of the putative risk allele Z-2 was found in patients of nephropathy and retinopathy groups compared with the uncomplicated group (32.2, 34.1 vs. 25.1%, respectively, P>0.05). Similarly, no difference was found in the frequency of the putative protective allele Z+2 among any of the study groups. In conclusion, the results of the study in Korean type 2 diabetic patients do not support the hypothesis that polymorphism at the 5' end of the aldose reductase gene contributes to the susceptibility to diabetic microvascular complications.

Aged↗
PubMed2001

Characterization of aberrant FHIT transcripts in gastric adenocarcinomas.

Aberrant transcripts of FHIT (fragile histidine triad) have been reported in several types of primary tumors and cell lines, including gastric carcinoma. The role of these aberrant transcripts in tumorigenesis is not clear yet. Forty-eight aberrant-sized FHIT transcripts with various lengths and number in 35 cases of gastric adenocarcinomas were further characterized. Aberrant transcripts, with deletions and/or insertions, were frequently observed in 20 cases of tumors. Sequence analysis demonstrated that different types of aberrant transcripts used normal splice sites but skipped exons, contained the inserts with the part of intron 5 sequences, or used the FHIT cDNA sequence 179-180 as a cryptic splice acceptor site. Most of aberrant transcripts lacked exon 5 and were presumably non-functional as the translation initiation codon is located in exon 5. Additionally, other transcripts, indicative of additional splice processing, either deletions or insertions, were expressed in several tumors. Taken together, our data indicate that the FHIT gene expression is frequently altered in gastric adenocarcinomas by aberrant splicing, and suggest that different types of aberrant transcripts may result during the multi-step splice processing.

Acid Anhydride Hydrolases↗
PubMed2001

pncA mutations in clinical Mycobacterium tuberculosis isolates from Korea.

BACKGROUND: Pyrazinamide (PZA) is among the first-line drugs for the treatment of tuberculosis. In vitro, it kills semidormant mycobacteria only at low pH. The purpose of this study was to compare PZA resistance with pyrazinamidase (PZase) activity and the genotype to better understand the molecular basis of PZA resistance and to expand the profile of pncA mutations worldwide. RESULTS: Of the 28 tested strains of Mycobacterium tuberculosis, 6 were susceptible to PZA and positive for PZase activity and had no pncA mutations. Twenty-one strains were resistant to PZA and negative for PZase activity and had mutations in the pncA gene, including 15 point mutations, 5 insertions, and 2 deletions. One strain had no mutation in the pncA gene, even though it was resistant to PZA and negative for PZase activity. Three isolates had adenine to guanine point mutations in the -11 upstream region, making this the most common type of pncA mutations in this study, with at least two different RFLP patterns. CONCLUSION: These data help in the understanding of the molecular basis of PZA resistance. An adenine to guanine point mutation in the -11 upstream region was the most common type of pncA mutation in our isolates. The results of pncA mutation analyses should be carefully interpreted for epidemiologic purposes.

Amidohydrolases↗