Biomedical subjects

C K Jung

Publications and source records attributed to C K Jung.

18 recordsLinked to original sources

PubMed2006

Measurement of atmospheric neutrino flux consistent with tau neutrino appearance.

A search for the appearance of tau neutrinos from nu(mu) <--> nu(tau) oscillations in the atmospheric neutrinos has been performed using 1489.2 days of atmospheric neutrino data from the Super-Kamiokande-I experiment. A best fit tau neutrino appearance signal of 138+/-48(stat)-32(+15)(syst) events is obtained with an expectation of 78+/-26(syst). The hypothesis of no tau neutrino appearance is disfavored by 2.4 sigma.

Journal Article↗

PubMed2006

Improved search for nu(mu) --> nu(e) oscillation in a long-baseline accelerator experiment.

We performed an improved search for nu(mu) --> nu(e) oscillation with the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment, using the full data sample of 9.2 x 10(19) protons on target. No evidence for a nu(e) appearance signal was found, and we set bounds on the nu(mu) --> nu(e) oscillation parameters. At Deltam(2)=2.8 x 10(-3) eV(2), the best-fit value of the K2Knu(mu) disappearance analysis, we set an upper limit of sin(2)2theta(mue) < 0.13 at a 90% confidence level.

Journal Article↗

PubMed2005

Search for coherent charged pion production in neutrino-carbon interactions.

We report the result from a search for charged-current coherent pion production induced by muon neutrinos with a mean energy of 1.3 GeV. The data are collected with a fully active scintillator detector in the K2K long-baseline neutrino oscillation experiment. No evidence for coherent pion production is observed, and an upper limit of is set on the cross section ratio of coherent pion production to the total charged-current interaction at 90% confidence level. This is the first experimental limit for coherent charged pion production in the energy region of a few GeV.

Journal Article↗

PubMed2005

Evidence for muon neutrino oscillation in an accelerator-based experiment.

We present results for nu(mu) oscillation in the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced nu(mu) beam with a mean energy of 1.3 GeV directed at the Super-Kamiokande detector. We observed the energy-dependent disappearance of nu(mu), which we presume have oscillated to nu(tau). The probability that we would observe these results if there is no neutrino oscillation is 0.0050% (4.0 sigma).

Journal Article↗

PubMed2004

Evidence for an oscillatory signature in atmospheric neutrino oscillations.

Muon neutrino disappearance probability as a function of neutrino flight length L over neutrino energy E was studied. A dip in the L/E distribution was observed in the data, as predicted from the sinusoidal flavor transition probability of neutrino oscillation. The observed L/E distribution constrained nu(micro)<-->nu(tau) neutrino oscillation parameters; 1.9x10(-3) 0.90 at 90% confidence level.

Journal Article↗

PubMed2004

Search for electron neutrino appearance in a 250 km long-baseline experiment.

We present a search for electron neutrino appearance from accelerator-produced muon neutrinos in the K2K long-baseline neutrino experiment. One candidate event is found in the data corresponding to an exposure of 4.8 x 10(19) protons on target. The expected background in the absence of neutrino oscillations is estimated to be 2.4+/-0.6 events and is dominated by misidentification of events from neutral current pi(0) production. We exclude the nu(micro) to nu(e) oscillations at 90% C.L. for the effective mixing angle in the 2-flavor approximation of sin((2)2theta(microe)( approximately 1/2sin((2)2theta(13))>0.15 at Deltam(2)(microe)=2.8 x 10(-3) eV(2), the best-fit value of the nu(micro) disappearance analysis in K2K. The most stringent limit of sin((2)2theta(microe)<0.09 is obtained at Deltam(2)(microe)=6 x 10(-3) eV(2).

Journal Article↗

PubMed2004

Limits on the neutrino magnetic moment using 1496 days of Super-Kamiokande-I solar neutrino data.

A search for a nonzero neutrino magnetic moment has been conducted using 1496 live days of solar neutrino data from Super-Kamiokande-I. Specifically, we searched for distortions to the energy spectrum of recoil electrons arising from magnetic scattering due to a nonzero neutrino magnetic moment. In the absence of a clear signal, we found micro(nu)</=(3.6x10(-10))micro(B) at 90% C.L. by fitting to the Super-Kamiokande day-night spectra. The fitting took into account the effect of neutrino oscillation on the shapes of energy spectra. With additional information from other solar neutrino and KamLAND experiments constraining the oscillation region, a limit of micro(nu)</=(1.1x10(-10))micro(B) at 90% C.L. was obtained.

Journal Article↗

PubMed2003

Search for nu(e) from the sun at Super-Kamiokande-I.

We present the results of a search for low energy nu(e) from the Sun using 1496 days of data from Super-Kamiokande-I. We observe no significant excess of events and set an upper limit for the conversion probability to nu(e) of the 8B solar neutrino. This conversion limit is 0.8% (90% C.L.) of the standard solar model's neutrino flux for total energy=8-20 MeV. We also set a flux limit for monochromatic nu(e) for E(nu(e))=10-17 MeV.

Journal Article↗

PubMed2003

Search for supernova relic neutrinos at Super-Kamiokande.

A search for the relic neutrinos from all past core-collapse supernovae was conducted using 1496 days of data from the Super-Kamiokande detector. This analysis looked for electron-type antineutrinos that had produced a positron with an energy greater than 18 MeV. In the absence of a signal, 90% C.L. upper limits on the total flux were set for several theoretical models; these limits ranged from 20 to 130 macro nu(e) cm(-2) s(-1). Additionally, an upper bound of 1.2 macro nu(e) cm(-2) s(-1) was set for the supernova relic neutrino flux in the energy region E(nu)>19.3 MeV.

Journal Article↗

PubMed2003

Indications of neutrino oscillation in a 250 km long-baseline experiment.

The K2K experiment observes indications of neutrino oscillation: a reduction of nu(mu) flux together with a distortion of the energy spectrum. Fifty-six beam neutrino events are observed in Super-Kamiokande (SK), 250 km from the neutrino production point, with an expectation of 80.1(+6.2)(-5.4). Twenty-nine one ring mu-like events are used to reconstruct the neutrino energy spectrum, which is better matched to the expected spectrum with neutrino oscillation than without. The probability that the observed flux at SK is explained by statistical fluctuation without neutrino oscillation is less than 1%.

Journal Article↗

PubMed2001

Solar 8B and hep neutrino measurements from 1258 days of Super-Kamiokande data.

Solar neutrino measurements from 1258 days of data from the Super-Kamiokande detector are presented. The measurements are based on recoil electrons in the energy range 5.0-20.0 MeV. The measured solar neutrino flux is 2.32+/-0.03(stat)+0.08-0.07(syst)x10(6) cm(-2) x s(-1), which is 45.1+/-0.5(stat)+1.6-1.4(syst)% of that predicted by the BP2000 SSM. The day vs night flux asymmetry (Phi(n)-Phi(d))/Phi(average) is 0.033+/-0.022(stat)+0.013-0.012(syst). The recoil electron energy spectrum is consistent with no spectral distortion. For the hep neutrino flux, we set a 90% C.L. upper limit of 40x10(3) cm(-2) x s(-1), which is 4.3 times the BP2000 SSM prediction.

Journal Article↗

PubMed2001

Constraints on neutrino oscillations using 1258 days of Super-Kamiokande solar neutrino data.

We report the result of a search for neutrino oscillations using precise measurements of the recoil electron energy spectrum and zenith angle variations of the solar neutrino flux from 1258 days of neutrino-electron scattering data in Super-Kamiokande. The absence of significant zenith angle variation and spectrum distortion places strong constraints on neutrino mixing and mass difference in a flux-independent way. Using the Super-Kamiokande flux measurement in addition, two allowed regions at large mixing are found.

Journal Article↗

PubMed2001

Epstein-Barr virus infection, drug resistance and prognosis in Korean T- and NK-cell lymphomas.

T-cell lymphomas are a biologically heterogeneous group of diseases with varying clinical presentations and outcomes. We tried to understand the effect of Epstein-Barr virus (EBV) on lymphogenesis, prognostic factors and drug resistance of T-cell lymphomas, and to establish their relationship with international prognostic factors. Formalin-fixed paraffin-embedded tissue sections from 35 patients (12 women and 23 men) with T-cell lymphomas were examined to detect the presence of EBV using RNA in situ hybridization for EBV-encoded small nuclear RNA (EBER) 1/2 and immunohistochemical stain for latent membrane protein (LMP)-1. We also tried to establish the expression of p53 and P-glycoprotein (P-gp) using immunohistochemistry. The distribution according to the subgroup was: two T-lymphoblastic lymphomas, 13 NK/T-cell lymphomas, one angioimmunoblastic T-cell lymphoma, 17 peripheral T-cell lymphomas, unspecified, and two anaplastic large cell lymphomas. The EBER was detected in 15 of 35 T-cell lymphomas (42.9%) and among these it was detected in five of 17 nodal lymphomas (29.4%) and 10 of 18 extranodal lymphomas (55.6%). There was close correlation between EBER positivity and NK/T-cell lymphoma (P = 0.032). Expression of LMP was found in a proportion of tumor cells in seven of the 15 EBER-positive cases (46.7%). There was no correlation between EBER expression and complete response (CR rate), but coexpression of EBER and p53 was associated with treatment failure (P = 0.047). The 18 patients (51.4%) with p53 expression had significantly poorer outcomes compared with the 17 patients without p53 expression (CR rate, P < 0.0005; overall survival, P = 0.0102). Twenty of 35 patients (57.1%) were positive for P-gp expression. P-gp expression was significantly associated with treatment failure (P = 0.001) and overall survival (P = 0.0089). Seventeen of 35 patients (48.6%) treated with systemic chemotherapy or radiation therapy achieved a CR after initial treatment. When the prognostic factors were grouped using the international prognostic index, the CR rate was 58.8% for the low risk group, 50.0% for the low-intermediate risk group, 14.3% for the high-intermediate risk group, and 0% for the high risk group. In conclusion, high incidence of EBV was detected among Korean patients with T-cell lymphomas. Our study supports the prediction that patients who express p53 and P-gp have a poorer prognosis than those who do not and this should be considered when treatment strategies for individual patients are selected.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2000

Shunt-independent surgical treatment of middle cranial fossa arachnoid cysts in children.

The best operative intervention for children with arachnoid cysts remains the subject of controversy. Recent reports stress that craniotomy for cyst fenestration is associated with a low incidence of morbidity and mortality and may leave the child shunt-independent. Among a total of 66 intracranial arachnoid cysts operated on in the authors' department from 1985 to 1997, 44 cases (67%) were located in the middle cranial fossa. A higher incidence in the first decade of life (53 cases) and a marked male predominance (45 cases) were recognized. Headache, cranial deformities, symptoms of raised intracranial pressure, and seizures constituted the most frequent features of the clinical presentation. To determine which treatment provides the greatest benefit with the lowest incidence of complications, the records of the 44 patients with arachnoid cysts in the middle cranial fossa were reviewed. The mean age of these patients was 4.6 years (range 0-16 years). Different types of initial surgical procedures were performed. In 33 patients with middle cranial fossa arachnoid cysts (MCFAC) the initial surgery took the form of craniotomy with excision of the cyst walls and fenestration into the basal cisterns. Shunting procedures were performed in 9 patients: cysto-peritoneal shunts (CPS) were placed in 4 patients and ventriculo-peritoneal shunts (VPS), in 3 patients, and cyst excision was performed in addition to CPS in 2 patients. Excision of the cyst membrane alone without fenestration was performed in 2 patients. The initial treatment was successful in terms of reduced symptoms and decreased cyst size, with no additional treatment needed for the cyst, in 79% (26/33) of patients who had undergone excision of the cyst walls and fenestration into the basal cisterns, compared with 66% (6/9) of patients who had undergone shunting procedures. Cyst membrane excision was not successful in any of the patients who underwent this procedure alone. No significant difference in morbidity was noted between these different treatment options. On follow-up CT scan and MRI, cysts of types I and II (Galassi classification) exhibited a steady tendency to reduction or obliteration. These results confirm that radical excision of the outer and inner membranes of the cyst wall with fenestration into the basal cistern is a safe and effective shunt-independent procedure for MCFAC, especially for those of types I and II.

Adolescent↗

PubMed2000

Decentration and tilt: silicone multifocal versus acrylic soft intraocular lenses.

PURPOSE: To compare differences in decentration and tilt between a silicone multifocal and an acrylic intraocular lens (IOL) by evaluating postoperative changes. SETTING: Department of Ophthalmology, College of Medicine, The Catholic University of Korea, Seoul, Korea. METHODS: Forty eyes of 20 patients with IOL implantation were randomized into 2 groups according to IOL type: 3-piece silicone multifocal IOL or 3-piece acrylic IOL. All lenses were implanted in the capsular bag through a clear corneal incision after continuous curvilinear capsulorhexis and phacoemulsification. The amount of the decentration and the degree of the tilt of each IOL were measured using the EAS-1000 anterior eye segment analysis system 1 day and 1 and 2 months after surgery. RESULTS: No significant difference in decentration and tilt was found among the 3 follow-ups or between lens types. CONCLUSION: Neither IOL decentration nor tilt showed significant progression up to 2 months in eyes with a silicone multifocal or acrylic IOL when the IOLs were placed properly in the capsular bag. The amount of decentration and tilt was similar between lens types.

Acrylic Resins↗

PubMed1999

Development and validation of real-time quantitative reverse transcriptase-polymerase chain reaction for monitoring gene expression in cardiac myocytes in vitro.

In this article we present validation of a real-time RT-PCR method to quantitate mRNA expression levels of atrial natriuretic peptide and c-fos in an in vitro model of cardiac hypertrophy. This method requires minimal sample and no postreaction manipulation. In real-time RT-PCR a dual-labeled fluorescent probe is degraded concomitant with PCR amplification. Input target mRNA levels are correlated with the time (measured in PCR cycles) at which the reporter fluorescent emission increases beyond a threshold level. The use of an oligo(dt) magnetic bead protocol to harvest poly(A) mRNA from cultured cells in 96-well plates minimized DNA contamination. We show that the GAPDH gene chosen for normalization of the RNA load is truly invariant throughout the biological treatments examined. We discuss two methods of calculating fold increase: a standard curve method and the DeltaDelta Ct method. Real-time quantitative RT-PCR was used to determine the time course of c-fos induction and the effect of varying doses of four known hypertrophy agents on atrial naturitic factor messenger RNA expression in cultured cardiac muscle cells. Our results agree with published data obtained from Northern blot analysis.

Animals↗

PubMed1998

Perioperative specific management of blood volume loss in craniosynostosis surgery.

Accurate assessment and replacement of blood loss and fluid-electrolyte deficit during craniosynostosis repair is difficult owing to patient size and the diversity of surgical technique. Forty-three patients undergoing primary craniosynostosis repair over a 10-year period were studied retrospectively to determine blood loss and fluid deficit and to assess blood transfusion practices during both intraoperative and postoperative periods. Blood loss was calculated on the basis of estimated red cell mass (ERCM) and fluid-electrolyte imbalance was investigated with blood samplings. Blood transfusion was considered appropriate if the postoperative or posttransfusion ERCM was within 12% of the preoperative value. Estimated fluid requirement (EFR) was used in 4 ml kg(-1) h(-1) except for neonates. Intraoperatively, 80% of all patients were appropriately managed with respect to blood transfusion and EFR. Postoperatively only 20% of the patients receiving transfusions were transfused appropriately. In 23.3% of these patients (10/43) unexpected respiratory distress developed immediately after their recovery from the anesthesia. With the measurement of estimated blood volume and allowable blood loss, appropriate transfusion could be achieved for the successful treatment of the primary craniosynostosis.

Blood Loss, Surgical↗

PubMed1997

Tumors of the orbit. Pitfalls of the surgical approach in 37 children with orbital tumor.

The authors review their experience with 37 children with orbital tumors, summarizing their surgical techniques, the indications applied, and the pitfalls of each surgical approach. Tumors located in the retro-ocular or intraorbital space were surgically excised through a transcranial approach (28 cases), while for tumors in other sites lateral orbitotomy (5 cases), medial orbitotomy (1 case) and biopsy (3 cases) were performed. A transcranial approach was used for tumors with intracranial extension and for those located in the orbital apex and deep medial orbital compartment. Lateral orbitotomy was used for tumors located in the superior, temporal or inferior compartment of the orbit and those in the lateral apex. A medial orbitotomy was used for tumors located medial to the optic nerve. Outcomes of the surgical intervention varied, depending on the pathology, location and extent of the individual tumors. To obtain optimal exposure and minimize functional deficits, the pitfalls of surgical approaches to orbital tumors are discussed.

Adolescent↗