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Biomedical subjects

S K Kim

Publications and source records attributed to S K Kim.

At least 19 recordsLinked to original sources
PubMed2007

The effects of container materials and buffer additives on decreasing the iodide concentration in a disposal vault for spent nuclear fuel.

To retard the migration of iodine released from a spent fuel after the break of a container, the reducing effects on the concentration of the iodide by container corrosion products and some buffer additives were examined in a solution with bentonite. Iron and copper, and their corrosion products scarcely reduced the iodide concentration. And kaolinite, chalcopyrite, pyrite, copper ore and galena, known as having a sorption property for iodine, did not noticeably sorb the iodide. However, palm active carbon, silver metal and Ag2O lowered the iodide concentration. Especially, Ag2O put into a disposal container would effectively hinder the migration of iodine to the outside of a disposal vault without a great loss if the pore size of the compacted buffer layer is maintained below 1 mu m.

Buffers↗
PubMed2007

Human amniotic fluid-derived stem cells have characteristics of multipotent stem cells.

OBJECTIVES: To characterize mesenchymal stem cell-like cells isolated from human amniotic fluid for a new source of therapeutic cells. MATERIALS: Fibroblastoid-type cells obtained from amniotic fluid at the time of birth. METHODS: The ability of ex vivo expansion was investigated until senescence, and stem cell-like characteristics were analyzed by examining differentiation potential, messenger RNA expression and immunophenotypes. RESULTS AND CONCLUSIONS: A morphologically homogenous population of fibroblastoid-type (HAFFTs) cells, similar to mesenchymal stem cells from bone marrow (BM-MSCs), was obtained at the third passage. The cells became senescent after 27 passages over a period of 8 months while undergoing 66 population doublings. Under appropriate culture conditions, by the 8th passage they differentiated into adipocytes, osteocytes, chondrocytes and neuronal cells, as revealed by oil red O, von Kossa, Alcian blue and anti-NeuN antibody staining, respectively. Immunophenotype analyses at the 17th passage demonstrated the presence of TRA-1-60; SSEA-3 and-4; collagen types I, II, III, IV and XII; fibronectin; alpha-SMA; vimentin; desmin; CK18; CD44; CD54; CD106; FSP; vWF; CD31; and HLA ABC. Reverse transcriptase-polymerase chain reaction analysis of the HAFFTs from passages 6-20 showed consistent expression of Rex-1, SCF, GATA-4, vimentin, CK18, FGF-5 and HLA ABC genes. Oct-4 gene expression was observed up to the 19th passage but not at the 20th passage. HAFFTs showed telomerase activity at the 5th passage with a decreased level by the 21st passage. Interestingly, BMP-4, AFP, nestin and HNF-4alpha genes showed differential gene expression during ex vivo expansion. Taken together, these observations suggest that HAFFTs are pluripotent stem cells that are less differentiated than BM-MSCs, and that their gene expression profiles vary with passage number during ex vivo expansion.

Amniotic Fluid↗
PubMed2006

Evidence for B-->eta'pi and improved measurements for B-->eta'K.

We report evidence for the exclusive two-body charmless hadronic B meson decay B-->eta'pi, and improved measurements of B-->eta'K. The results are obtained from a data sample of 386x10(6) BB pairs collected at the Upsilon(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure B(B+-->eta'pi+)=[1.76(-0.62)(+0.67)(stat)(-0.14)(+0.15)(syst)]x10(-6) and B(B0-->eta'pi0)=[2.79(-0.96)(+1.02)(stat)(-0.34)(+0.25)(syst)]x10(-6). We also find the ratio of B(B+-->eta'K+)/B(B0-->eta'K0)=1.17+/-0.08(stat)+/-0.03(syst) and measure the direct CP asymmetries for the charged modes.

Journal Article↗
PubMed2006

Evidence for large direct CP violation in B+/- --> rho(770)0K+/- from analysis of three-body charmless B+/- --> K+/-pi+/-pi+/- decays.

We report results on a Dalitz analysis of three-body charmless B+/- --> K+/-pi+/-pi+/- decay including searches for direct CP violation. We report the first observation of the decay B+/- --> f2(1270)K+/- with a statistical significance above 6sigma. We also observe first evidence for large direct CP violation in the B+/- --> rho(770)0K+/- channel. The results are obtained with a data sample that contains 386 10(6) BB pairs collected at the Y(4s) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

Journal Article↗
PubMed2006

Measurement of forward-backward asymmetry and Wilson coefficients in B --> K*l+l-.

We report the first measurement of the forward-backward asymmetry and the ratios of Wilson coefficients and in A9/A7 and A10/A7 in B --> K*l+l-, where l represents an electron or a muon. We find evidence for the forward-backward asymmetry with a significance of 3.4sigma. The results are obtained from a data sample containing 386 x 10(6) BB pairs that were collected on the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

Journal Article↗
PubMed2006

Measurement of azimuthal asymmetries in inclusive production of hadron pairs in e(+)e(-) annihilation at Belle.

The Collins effect connects transverse quark spin with a measurable azimuthal dependence in the yield of hadronic fragments around the quark's momentum vector. Using two different reconstruction methods, we find evidence of statistically significant azimuthal asymmetries for charged pion pairs in e(+)e(-) annihilation at a center-of-mass energy of 10.52 GeV, which can be attributed to a transverse polarization of the primordial quarks. The measurement was performed using a sample of 79 x 10(6) hadronic events collected with the Belle detector.

Journal Article↗
PubMed2006

Active immunization against ghrelin decreases weight gain and alters plasma concentrations of growth hormone in growing pigs.

Ghrelin has been implicated in the control of food intake and in the long-term regulation of body weight. We theorize that preventing the ability of ghrelin to interact with its receptors, would eventually lead to decreased appetite and thereby decrease body weight gain. To test our hypothesis, pigs were actively immunized against ghrelin. Ghrelin((1-10)) was conjugated to BSA and emulsified in Freund's incomplete adjuvant and diethylaminoethyl-dextran. Primary immunization was given at 19 weeks of age (WOA), with booster immunizations given 20 and 40 days after primary immunization. Body weight (BW) and plasma samples were collected weekly beginning at 19 WOA, and feed intake was measured daily. Fourteen days after primary immunization, the percentage of bound (125)I-ghrelin in plasma from immunized pigs was increased compared with control animals (P<0.001). Voluntary feed intake was decreased more than 15% in animals that were actively immunized against ghrelin compared with controls. By the end of the experiment, immunized pigs weighed 10% less than control animals (P<0.1). Concentrations of GH were increased (P<0.05) in immunized pigs. Apoptosis was not observed in post-mortem samples obtained from the fundic region of the stomach. Our observations suggest that immunization against ghrelin induces mild anorexia. This procedure could potentially be used as a treatment to control caloric intake and obesity.

Animals↗
PubMed2006

Measurement of the branching fraction, polarization, and asymmetry for decays, and determination of the Cabibbo-Kobayashi-Maskawa phase.

We have measured the branching fraction , longitudinal polarization fraction f(L), and CP asymmetry coefficients A and S for B(0) --> rho(+) rho(-) decays with the Belle detector at the KEKB e(+) e(-) collider using 253 Fb(-1) of data. We obtain B = [22.8 +/- 3.8(stat)(+2.3)(-2.6)(syst)] x 10(-6), f(L) = 0.941 (+0.034)(-0.040)(stat) +/- 0.030(syst). A = 0.00 +/- 0.30(stat) +/- 0.09(syst) and S = 0.08 +/- 0.09(syst). These values are used to constrain the Cabibbo-Kobayashi-Maskawa phase ; the solution consistent with the standard model is phi(2) = (88 +/- 17) degrees or 59 degrees < phi(2) < 115 degrees at 90% C.L.

Journal Article↗
PubMed2006

Improved constraints on D0-D0 mixing in D0 --> K+ pi- decays from the Belle detector.

We report the results of a search for D0-D0 mixing in D0 --> K+ pi- decays based on 400 fb(-1) of data accumulated by the Belle detector at KEKB. Both assuming CP conservation and allowing for CP violation, we fit the decay-time distribution for the mixing parameters x and y, as well as for the parameter R(D), the ratio of doubly Cabibbo-suppressed decays to Cabibbo-favored decays. The 95% confidence level region in the (x'2,y') plane is obtained using a frequentist method. Assuming CP conservation, we find x'2 < 0.72 x 10(-3) and -9.9 x 10(-3) < y' < 6.8 x 10(-3) at the 95% confidence level; these are the most stringent constraints on the mixing parameters to date. The no-mixing point (0,0) has a confidence level of 3.9%. Assuming no mixing, we measure R(D) = (0.377 +/- 0.008 +/- 0.005)%.

Journal Article↗
PubMed2006

The privacy of T cell memory to viruses.

T cell responses to viral infections can mediate either protective immunity or damaging immunopathology. Viral infections induce the proliferation of T cells specific for viral antigens and cause a loss in the number of T cells with other specificities. In immunologically naive hosts, viruses will induce T cell responses that, dependent on the MHC, recognize a distinct hierarchy of virus-encoded T cell epitopes. This hierarchy can change if the host has previously encountered another pathogen that elicited a memory pool ofT cells specific to a cross-reactive epitope. This heterologous immunity can deviate the normal immune response and result in either beneficial or harmful effects on the host. Each host has a unique T cell repertoire caused by the random DNA rearrangement that created it, so the specific T cells that create the epitope hierarchy differ between individuals. This "private specificity" seems of little significance in the T cell response of a naive host to infection, but it is of profound importance under conditions of heterologous immunity, where a small subset of a cross-reactive memory pool may expand and dominate a response. Examples are given of how the private specificities of immune responses under conditions of heterologous immunity influence the pathogenesis of murine and human viral infections.

Animals↗
PubMed2006

Biological responses of anodized titanium implants under different current voltages.

The oxide layer of a titanium surface is very stable, and seems to result in excellent biocompatibility and successful osseointegration. The purpose of this study was to investigate the effects of high anodic oxidation voltages on the surface characteristics of titanium implants and the biologic response of rabbit tibiae. Bone tissue responses were evaluated by removal torque tests and histomorphometric analysis. Screw-shaped implants with microthreads were made of commercially pure titanium (Grade II). We prepared anodized implants under 300 V (group I), 400 V (group II), 500 V (group III) and 550 V (group IV). The surface characteristics of specimens were inspected according to three categories: surface morphology, surface roughness and oxide layer thickness. The screw-shaped implants were installed in rabbit tibiae. The removal torque values were measured and histomorphometric analysis was done after 1- and 3-month healing periods. Data indicate that as anodic oxidation voltage increased above 300 V, oxide layer thickness increased rapidly and pore size also increased. The roughness values of the implants increased with voltage up to 500 V, but decreased at 550 V. In the removal torque test, group III showed higher values than groups I and II at a statistically significant level (P < 0.05) after a 1-month healing period. In histomorphometric analysis, groups III and IV, after a 3-month healing period, showed greater bone to implant contact ratios for the total implant surface than did group I (P < 0.05).

Animals↗
PubMed2006

Tissue-specific regulation of malonyl-CoA decarboxylase activity in OLETF rats.

AIM: The intracellular concentration of malonyl-CoA, a key regulator of fatty acid oxidation, is determined both from its synthesis by acetyl-CoA carboxylase and from its degradation by malonyl-CoA decarboxylase (MCD). The aim of our study was to investigate the activity and mRNA expression of MCD under insulin resistance and after treatment with insulin sensitizers in different tissues. METHODS: We treated 18-week Otusuka Long-Evans Tokushima Fatty (OLETF) rats with pioglitazone (10 mg/kg/day) or metformin (300 mg/kg/day) for 8 weeks and determined the activity and mRNA expression of MCD in diabetic OLETF and non-diabetic Long-Evans Tokushima Otsuka (LETO) rats in myocardial and skeletal muscles, and in liver. RESULTS: The MCD activities of myocardial and skeletal muscles were remarkably reduced in OLETF rats compared with LETO rats (995 +/- 114 vs. 2012 +/- 359, 58 +/- 11 vs. 167 +/- 40 pmol/min/mg protein; p = 0.005 and p = 0.010). Surprisingly, after pioglitazone treatment, not after metformin, the MCD activities of myocardial and skeletal muscles (1906 +/- 320 and 259 +/- 44 pmol/min/mg protein) increased up to the levels in LETO rats. MCD mRNA expression in OLETF rats was also reduced in myocardial and skeletal muscles vs. LETO rats (p = 0.049 and p = 0.008) and was unchanged by pioglitazone or metformin treatment. In the liver, MCD activity and mRNA expression were similar in OLETF and LETO rats. CONCLUSION: Pioglitazone treatment restored MCD activity to non-diabetic level and improved the restrained fatty acid metabolism in myocardial and skeletal muscles caused by insulin-resistant diabetic status.

Animals↗
PubMed2005

Measurements of B decays to two kaons.

We report measurements of B meson decays to two kaons using 253 fb(-1) of data collected with the Belle detector at the KEKB energy-asymmetric e+ e- collider. We find evidence for signals in B+ --> K0 K+ and B0 --> K0 K0 with significances of 3.0sigma and 3.5sigma, respectively. (Charge-conjugate modes are included.) The corresponding branching fractions are measured to be [symbol: see text](B+ --> K0 K+) = (1.0 +/- 0.4 +/- 0.1) x 10(-6) and [symbol: see text](B0 --> K0 K0) = (0.8 +/- 0.3 +/- 0.1) x 10(-6). These decay modes are examples of hadronic bd transitions. No signal is observed in the decay B0 --> K+ K-, and we set an upper limit of 3.7 x 10(-7) at 90% confidence level.

Journal Article↗
PubMed2005

Measurement of the wrong-sign decays D0 --> K+ pi- pi0 and D0 --> K+ pi- pi+ pi-, and search for CP violation.

Using 281 fb-1 of data from the Belle experiment recorded at or near the (4S) resonance, we have measured the rates of the "wrong-sign" decays D0 --> K+ pi- pi0 and D0 --> K+ pi- pi+ pi- relative to those of the Cabibbo-favored decays D0 --> K- pi+ pi0 and D0 --> K- pi+ pi+ pi-. These wrong-sign decays proceed via a doubly Cabibbo-suppressed amplitude or via D0-D0 mixing; the latter has not yet been observed. We obtain R(WS)(K pi pi0) = [0.229 +/- 0.015(stat)(+0.013)(-0.009)(syst)]% and R(WS)(K3pi) = [0.320 +/- 0.018(stat)(+0.018)(0.013)(syst)]%. The CP asymmetries are measured to be -0.006 +/- 0.053 and -0.018 +/- 0.044 for the K+ pi- pi0 and K+ pi- pi+ pi- final states, respectively.

Journal Article↗
PubMed2005

Radiofrequency thermal ablation of hepatic tumors: pitfalls and challenges.

Image-guided radiofrequency (RF) thermal ablation has been accepted as a promising interventional technique to control unresectable hepatic tumors. One important key to maximize the efficacy of RF ablation is to adhere to the therapeutic guidelines and to avoid preventable pitfalls. There are also several challenges obstructing successful ablation: poor approach path; small sonic window during multiple overlapping ablations; incomplete ablation due to the heat sink effect; subcapsular mass (too exophytic or the mass is adjacent to the gastrointestinal tract); focal residual tumors; too isoechoic or small masses; and mistargeting to adjacent another lesion. Knowledge of these challenges and pitfalls in RF ablation is helpful for a successful ablation.

Catheter Ablation↗
PubMed2005

Comparison of the efficacy of Burch colposuspension, pubovaginal sling, and tension-free vaginal tape for stress urinary incontinence.

OBJECTIVE: To compare the cure rate and confirm the clinical efficacy of the 3 most frequently performed surgical procedures for stress urinary incontinence (SUI). METHODS: Between January 2001 and May 2003, 92 women with SUI were randomly assigned to undergo the Burch colposuspension (n=33), pubovaginal sling (n=28), or tension-free vaginal tape (n=31) at the Department of Obstetrics and Gynecology, Yonsei Medical Center, Seoul, Korea. Patient characteristics, urodynamic study results, cure rates at 3, 6, and 12 months, and complication rates were compared using the chi2 test. RESULTS: There were no statistically significant differences in the cure rates initially, but after 12 months the cure rate of the pubovaginal sling procedure was found to be significantly higher than those of the tension-free vaginal tape or Burch colposuspension procedures. CONCLUSION: The cure rate of the pubovaginal sling procedure was significantly higher after 1 year, but no difference in efficacy was observed between the 2 other procedures. A randomized prospective study of a larger population should be conducted.

Female↗