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Biomedical subjects

K Kim

Publications and source records attributed to K Kim.

At least 19 recordsLinked to original sources
PubMed2006

Process tomography of ion trap quantum gates.

A crucial building block for quantum information processing with trapped ions is a controlled-NOT quantum gate. In this Letter, two different sequences of laser pulses implementing such a gate operation are analyzed using quantum process tomography. Fidelities of up to 92.6(6)% are achieved for single-gate operations and up to 83.4(8)% for two concatenated gate operations. By process tomography we assess the performance of the gates for different experimental realizations and demonstrate the advantage of amplitude-shaped laser pulses over simple square pulses. We also investigate whether the performance of concatenated gates can be inferred from the analysis of the single gates.

Journal Article↗
PubMed2006

Changes in the levels of interferon-gamma and transforming growth factor-beta influence bronchial stenosis during the treatment of endobronchial tuberculosis.

BACKGROUND: Endobronchial tuberculosis (EBTB) has been shown to frequently complicate bronchial stenosis, a condition which can induce dyspnea as a result of airway obstruction, and is also frequently misdiagnosed as either bronchial asthma or lung cancer. OBJECTIVES: This study attempted to determine whether there was a correlation between interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) levels in the serum and bronchial washing fluid (BWF), and the results of the treatment of EBTB patients. METHODS: Thirty patients, all of whom were diagnosed as EBTB, were enrolled, as were 10 healthy control subjects. IFN-gamma and TGF-beta levels were measured by the ELISA method in the serum and BWF of these 30 EBTB patients before and after treatment. The EBTB patients were divided into two groups: those who exhibited bronchial stenosis after treatment and those who did not. Chest computed tomography (CT) and pulmonary function test (PFT) were performed in 16 and 25 patients, respectively, at initial bronchoscopy. RESULTS: IFN-gamma and TGF-beta levels in the BWF of the EBTB patients were elevated compared to the controls (p < 0.05). After 2 months of treatment, 13 of the 30 EBTB patients exhibited bronchial fibrostenosis and the other 17 cases had recovered without sequelae. In the bronchial stenosis group, the initial serum TGF-beta levels were lower than in the patients without bronchial stenosis (p < 0.05). Moreover, the levels of serum TGF-beta after treatment were shown to have decreased more than in the patients without bronchial stenosis (p < 0.05). On chest CT findings of 16 EBTB patients, bronchial narrowing was suspected except in 2 cases (1 edematous-hyperemic type, 1 actively caseating type of segmental bronchus). The common features of PFT in EBTB at the initial diagnosis were a restrictive pattern and normal ventilatory function. CONCLUSIONS: Elevated IFN-gamma and TGF-beta levels in the BWF of the EBTB patients may be related to EBTB pathogenesis. Lowered initial serum TGF-beta levels as well as the observed changes in the levels of TGF-beta in the serum after treatment have been implicated in bronchial fibrostenosis during the course of the disease.

Adult↗
PubMed2006

'Designer atoms' for quantum metrology.

Entanglement is recognized as a key resource for quantum computation and quantum cryptography. For quantum metrology, the use of entangled states has been discussed and demonstrated as a means of improving the signal-to-noise ratio. In addition, entangled states have been used in experiments for efficient quantum state detection and for the measurement of scattering lengths. In quantum information processing, manipulation of individual quantum bits allows for the tailored design of specific states that are insensitive to the detrimental influences of an environment. Such 'decoherence-free subspaces' (ref. 10) protect quantum information and yield significantly enhanced coherence times. Here we use a decoherence-free subspace with specifically designed entangled states to demonstrate precision spectroscopy of a pair of trapped Ca+ ions; we obtain the electric quadrupole moment, which is of use for frequency standard applications. We find that entangled states are not only useful for enhancing the signal-to-noise ratio in frequency measurements--a suitably designed pair of atoms also allows clock measurements in the presence of strong technical noise. Our technique makes explicit use of non-locality as an entanglement property and provides an approach for 'designed' quantum metrology.

Journal Article↗
PubMed2006

Single-atom optical clock with high accuracy.

For the past 50 years, atomic standards based on the frequency of the cesium ground-state hyperfine transition have been the most accurate time pieces in the world. We now report a comparison between the cesium fountain standard NIST-F1, which has been evaluated with an inaccuracy of about 4 x 10(-16), and an optical frequency standard based on an ultraviolet transition in a single, laser-cooled mercury ion for which the fractional systematic frequency uncertainty was below 7.2 x 10(-17). The absolute frequency of the transition was measured versus cesium to be 1,064,721,609,899,144.94 (97) Hz, with a statistically limited total fractional uncertainty of 9.1 x 10(-16) the most accurate absolute measurement of an optical frequency to date.

Journal Article↗
PubMed2006

Drosophila homolog of APP-BP1 (dAPP-BP1) interacts antagonistically with APPL during Drosophila development.

beta-Amyloid precursor protein binding protein 1 (APP-BP1) was previously identified based on its binding to the carboxyl terminal of beta-amyloid precursor protein. In this report, we have discovered that a mutation of dAPP-BP1 (Drosophila ortholog of APP-BP1) hinders tissue development, causes apoptosis in imaginal disc cells, and blocks the NEDD8 conjugation pathway. We show that dAPP-BP1 specifically binds the intracellular domain of APP-like protein (APPL). The dAPP-BP1 mutation partially suppresses the abnormal macrochaete phenotype of Appl(d), while overexpression of dAPP-BP1 causes abnormal macrochaetes. When APPL is overexpressed, the normal bristle pattern in the fly thorax is disturbed and apoptosis is induced in wing imaginal discs. APPL overexpression phenotypes are enhanced by reducing the level of dAPP-BP1. APPL overexpression is shown to inhibit the NEDD8 conjugation pathway. APPL-induced apoptosis is rescued by overexpression of dAPP-BP1. Our data suggest that APPL and dAPP-BP1 interact antagonistically during Drosophila development.

Amino Acid Sequence↗
PubMed2006

Repeated brief epileptic seizures by pentylenetetrazole cause neurodegeneration and promote neurogenesis in discrete brain regions of freely moving adult rats.

Recurrent epileptic seizures are known to provoke various forms of cellular reorganization in the brains of humans and experimental animals. However, little is known about the mechanism of neuronal cell death resulting from epileptic seizures elicited by GABA antagonists. In the present study, we explored the effect on the central nervous systems of freely moving adult rats, of repeated brief epileptic seizures induced by systemic injection of pentylenetetrazole, a GABA-A receptor antagonist. Starting with minor convulsions, repeated epileptic seizures elicited a progressive increase in seizure severity, culminating in the fully kindled state. Histological examination showed that the epileptic seizures caused overt neuronal cell death in the limbic system, including the hippocampus and amygdala, and its adjoining cortex. During the recurrent epileptic seizures, neurogenesis occurred in the subgranular zone of the hippocampus, the subventricular zone of the lateral ventricle, and the amygdala. This type of pentylenetetrazole-induced neurogenesis was seen at an early stage of epileptogenesis in some regions in which massive cell loss was not evident. This suggests that neurogenesis is not a secondary consequence of neuronal cell death, but rather an independent effect of recurrent epileptic seizures.

Animals↗
PubMed2006

The effect of Epstein-Barr virus status on clinical outcome in Hodgkin's lymphoma.

The association of Epstein-Barr virus (EBV) with Hodgkin's lymphoma (HL) has been investigated over the last few years. The impact of EBV on clinical outcome is still controversial, however. In this study, we investigated the effect of EBV status on clinical outcome of HL patients. Between January 1986 and September 2004, fifty-six patients, diagnosed as having HL, were included in the analysis. Clinical data were reviewed retrospectively from the patients' records. Tissues from 56 patients were analyzed for the presence of EBV using the in situ hybridization (ISH) for EBV-encoded RNA (EBER) and immunohistochemistry for latent membrane protein (LMP)1. EBV infection was identified in 41.1% of cases by EBER ISH, 26.8% by LMP1 expression, and 26.8% by LMP1 and EBER ISH. EBER-positive HL were significantly more frequent in mixed cellularity (MC) subtype (P=0.014) and advanced stage (P=0.034). There was a trend toward shorter overall survival in EBER-positive patients without statistical significance (P=0.238). LMP1 expression also correlated with MC subtype (P=0.006) and advanced stage (P=0.007), although it did not significantly influence the survival outcome. In subgroup analysis, both EBER and LMP1 positivities were associated with longer progression-free survival in patients with age <25 years old (P=0.045). Reverse trends were shown in patients > or =25 years old. In this study, we demonstrated that the impact of tumor EBV status on prognosis may be age dependent and young patients with latent EBV infection have favorable prognosis.

Adult↗
PubMed2006

Measurement of two- and three-nucleon short-range correlation probabilities in nuclei.

The ratios of inclusive electron scattering cross sections of 4He, 12C, and 56Fe to 3He have been measured at 1 < xB <. At Q2 > 1.4 GeV2, the ratios exhibit two separate plateaus, at 1.5 < xB < 2 and at xB > 2.25. This pattern is predicted by models that include 2- and 3-nucleon short-range correlations (SRC). Relative to A = 3, the per-nucleon probabilities of 3-nucleon SRC are 2.3, 3.1, and 4.4 times larger for A = 4, 12, and 56. This is the first measurement of 3-nucleon SRC probabilities in nuclei.

Journal Article↗
PubMed2006

Improved stabilization of a 1.3 microm femtosecond optical frequency comb by use of a spectrally tailored continuum from a nonlinear fiber grating.

We report significant enhancement (+24 dB) of the optical beat note between a 657 nm cw laser and the second-harmonic generation of the tailored continuum at 1314 nm generated with a femtosecond Cr:forsterite laser and a nonlinear fiber Bragg grating. The same continuum is used to stabilize the carrier-envelope offset frequency of the Cr:forsterite femtosecond laser and permits improved optical stabilization of the frequency comb from 1.0 to 2.2 microm. Using a common optical reference at 657 nm, a relative fractional frequency instability of 2.0 x 10(-15) is achieved between the repetition rates of Cr:forsterite and Ti:sapphire laser systems in 10 s averaging time. The fractional frequency offset between the optically stabilized frequency combs of the Cr:forsterite and Ti:sapphire lasers is +/-(0.024 +/- 6.1) x 10(-17).

Journal Article↗
PubMed2006

Rare cases of Ménière's disease in children.

Classical Ménière's disease is rarely found in children and literature regarding it is scarce. In general, the frequency of Ménière's disease in children is only 0.4-7.0 per cent of that in adults. The progression pattern of Ménière's disease in children is not known well. Here, we report three cases of Ménière's disease in children less than 15 years old, treated over nine years. The three cases comprise 14- and 13-year-old boys and a nine-year-old girl. Two of the three patients initially complained only of recurrent bouts of vertigo, without any tinnitus, ear fullness or hearing impairment. In all three cases, the early pure tone audiograms showed only high tone frequency loss, regardless of subjective hearing loss, and the decrease in the hearing threshold was observed one to eight years after the dizziness attacks began. The hearing threshold was usually decreased to a level of mild or moderate hearing impairment. After diuretic treatment, vertigo was generally well controlled, and some cases showed improvement in hearing. Of the total number of patients with Ménière's disease who visited our department over nine years, 2.6 per cent (3/114) were children, and the overall incidence of Ménière's disease in children with vertigo was 2.0 per cent (3/147). In conclusion, Ménière's disease in children rarely develops and may have characteristics of high tone loss in initial audiograms.

Adolescent↗
PubMed2006

High-dose chemotherapy with autologous stem cell transplantation in extranodal NK/T-cell lymphoma: a retrospective comparison with non-transplantation cases.

To determine the role of high-dose chemotherapy and autologous stem cell transplantation (HDC/ASCT) in extranodal NK/T-cell lymphoma patients, we conducted a retrospective analysis. In our previous study, we searched for patients who had received HDC/ASCT and identified 16 eligible patients and compared the treatment outcome with historical control group (n=246). Nine patients received HDC/ASCT in the first (CR1) or second complete remission (CR2), while seven patients received HDC/ASCT as salvage. Twelve of 16 patients achieved or maintained CR after HDC/ASCT. Among the 12 patients, five patients relapsed. Estimated 2-year overall survival (OS) and relapse-free survival (RFS) rates were 71.3+/-12.4% and 25.8+/-14.3%, respectively. There was a tendency of better survival in patients who received HDC/ASCT as compared to those who did not (P=0.091). In subset analysis, patients who underwent HDC/ASCT at CR (P=0.049) and patients with stage III or IV (P=0.001) had a favorable outcome. Patients with NKIPI 3,4 or EUNKTL, who underwent HDC/ASCT had more prolonged survival without statistical significance (P=0.055 and 0.056). In conclusion, HDC/ASCT may be considered as a treatment option for patients with extranodal NK/T-cell lymphoma, especially those in CR, with advanced disease (stage III/IV or EUNKTL) and high NKIPI scores.

Adolescent↗
PubMed2006

Usefulness of (18)F-fluorodeoxyglucose PET for radiosurgery planning and response monitoring in patients with recurrent spinal metastasis.

INTRODUCTION: With the advancement and successful treatment of metastatic spinal cord disease, newer treatments are needed for the long-term survivors of recurrent disease. The lack of a standardized re-treatment regimen and the difficulty in delineating the tumor margins among patients who have received the treatment with metallic spinal fixation and conventional radiation are two of the challenges to be faced in recurrent metastatic spinal cord disease. In these patients, we applied hypofractionated stereotactic radiosurgery by defining the tumor margin with (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET). PATIENTS AND METHODS: Three consecutive recurrent spinal metastasis patients underwent the CyberKnife treatment (Accuray, Inc., Sunnyvale, CA) from March 2004 to July 2004. A three-fraction schedule was applied at approximately 24 hour intervals. One patient had sarcoma and the other two patients had breast cancer. All patients had received previous conventional radiotherapy after operation ranging from 30 Gy to 45 Gy. CT-based planning was corrected by the FDG-PET hyperuptake area with the help of nuclear medicine. The mass responses were followed not only by MRI but also by FDG-PET, which was taken prior to treatment, and at one and six months after the treatment. The changes in standard uptake value (SUV) of serial PET were taken as a measure of response. To evaluate the relative SUV changes from different pretreatment values, we set a reduction index (RI), which represents the ratio of SUV change to pretreatment SUV. RESULTS: No significant complications were noted during treatment with a mean follow-up of 13.3 months. The tumor volume on CT-based planning was 2.2 times larger than that of the CT-PET combined planning in case 1 of paraspinal muscle invasion. But the tumor volumes showed minimal changes in the other cases, in which the metastatic tumors were confined to the vertebral bodies. The SUV one month after treatment showed variable decreases and the RI ranged from 0.07 to 0.7. However, the SUVs at 6 months were well correlated with the clinical results. One patient showed marginal failure and the other two patients showed local control of the tumor, as their RI values were 0.65 and 0.87, respectively. CONCLUSION: To our knowledge, this is the first report using FDG-PET with radiosurgery in patients with recurrent spinal metastases hidden under metallic artifacts. The mass responses measured by SUV changes in FDG-PET correlated with the clinical results.

Adult↗
PubMed2006

A high filtration system with synthetic permeable media for wastewater reclamation.

A novel filtration process with synthetic permeable media was investigated for secondary effluent reclamation. Polyurethane was chosen as the filter medium among three tested media. Compressibility and up-flow velocity were changed to determine the optimum operation for the system. An equation was introduced to express the relationship between the removal efficiency and up-flow velocity. In a pilot study, the synthetic medium filtration with compression showed very stable effluent quality without clogging trouble, though the system operated with three times higher filtration rate and much longer backwashing interval than conventional systems.

Filtration↗
PubMed2006

3T 1H-MR spectroscopy in grading of cerebral gliomas: comparison of short and intermediate echo time sequences.

BACKGROUND AND PURPOSE: Echo time (TE) can have a large influence on the spectra in proton MR spectroscopy ((1)H-MR spectroscopy). The purpose of this study was to comparatively assess the diagnostic value of 3T single-voxel (1)H-MR spectroscopy with short or intermediate TEs in grading cerebral gliomas. METHODS: Single voxel (1)H-MR spectroscopy was performed at 3T in 35 patients with cerebral glioma. The spectra were obtained with both short (35 ms) and intermediate TEs (144 ms). Metabolite ratios of choline (Cho)/creatine (Cr), Cho/N-acetylaspartate (NAA), lipid and lactate (LL)/Cr and myo-inositol (mIns)/Cr were calculated and compared between short and intermediate TEs in each grade. After receiver operating characteristic curve analysis, diagnostic accuracy for each TE in differentiating high-grade glioma from low-grade glioma was compared. RESULTS: At short TE, Cho/Cr and Cho/NAA ratios were significantly lower, and LL/Cr and mIns/Cr were significantly higher, compared with those at intermediate TE, regardless of tumor grade. Lactate inversion at intermediate TE was found in only 2 patients. At both TEs, there were significant differences in Cho/Cr and LL/Cr ratios between low- and high-grade gliomas. Diagnostic accuracy was slightly higher at short TE alone or combined with intermediate TE than intermediate TE alone (85.7% versus 82.9%). CONCLUSION: Metabolite ratios were significantly different between short and intermediate TE. Cho/Cr and LL/Cr ratios at either TE were similarly useful in differentiating high-grade gliomas from low-grade gliomas. If only a single spectroscopic sequence can be acquired, short TE seems preferable because of poor lactate inversion at intermediate TE on 3T single-voxel (1)H-MR spectroscopy.

Adult↗
PubMed2005

Giant intracranial aneurysm of the anterior communicating artery treated by direct surgery using A3-A3 side-to-side anastomosis and A3-RA graft-STA anastomosis.

We describe a giant aneurysm of the anterior communicating artery (ACoA) which was treated with a STA-RA graft-A3 bonnet bypass and A3-A3 side-to-side anastomosis. A giant and partially thrombosed ACoA aneurysm was partially coated 3 years before his current presentation, its gradual increase producing visual field disturbances. An A3-A3 side-to-side anastomosis and STA-RA graft-A3 bonnet bypass were performed. The aneurysm was dissected, and the thrombus removed under transient parent-artery occlusion. The aneurysmal neck was successfully clipped without encountering ischemic changes. This strategy may be useful for treating giant or thrombosed aneurysms in the region of the ACoA.

Adult↗
PubMed2005

Effects of calibration on L-THIA GIS runoff and pollutant estimation.

Urbanization can result in alteration of a watershed's hydrologic response and water quality. To simulate hydrologic and water quality impacts of land use changes, the Long-Term Hydrologic Impact Assessment (L-THIA) system has been used. The L-THIA system estimates pollutant loading based on direct runoff quantity and land use based pollutant coefficients. The accurate estimation of direct runoff is important in assessing water quality impacts of land use changes. An automated program was developed to calibrate the L-THIA model using the millions of curve number (CN) combinations associated with land uses and hydrologic soil groups. L-THIA calibration for the Little Eagle Creek (LEC) watershed near Indianapolis, Indiana was performed using land use data for 1991 and daily rainfall data for six months of 1991 (January 1-June 30) to minimize errors associated with use of different temporal land use data and rainfall data. For the calibration period, the Nash-Sutcliffe coefficient was 0.60 for estimated and observed direct runoff. The calibrated CN values were used for validation of the model for the same year (July 1-December 31), and the Nash-Sutcliffe coefficient was 0.60 for estimated and observed direct runoff. The Nash-Sutcliffe coefficient was 0.52 for January 1, 1991 to December 31, 1991 using uncalibrated CN values. As shown in this study, the use of better input parameters for the L-THIA model can improve accuracy. The effects on direct runoff and pollutant estimation of the calibrated CN values in the L-THIA model were investigated for the LEC. Following calibration, the estimated average annual direct runoff for the LEC watershed increased by 34%, total nitrogen by 24%, total phosphorus by 22%, and total lead by 43%. This study demonstrates that the L-THIA model should be calibrated and validated prior to application in a particular watershed to more accurately assess the effects of land use changes on hydrology and water quality.

Calibration↗
PubMed2005

Salvage chemotherapy with irinotecan, 5-fluorouracil and leucovorin for taxane- and cisplatin-refractory, metastatic gastric cancer.

We performed a phase II study of combination chemotherapy with irinotecan, 5-fluorouracil (5-FU) and leucovorin in metastatic gastric cancer patients who were previously treated with taxane and cisplatin, to evaluate the antitumour activity and toxicity of the combination chemotherapy. The metastatic gastric adenocarcinoma patients who were previously treated with taxane and cisplatin combination as first line, and had at least one measurable lesion, 0-2 ECOG performance status and adequate organ functions, were considered eligible. They received irinotecan (150 mg m(-2), day 1) and leucovorin (100 mg m(-2), day 1), followed by continuous infusion of 5-FU (1000 mg m(-2) day(-1), days 1 and 2) every 2 weeks. Treatment was continued until progression of disease was observed. In all, 64 patients were treated with this combination chemotherapy. The median age of the patients was 55 years (range, 33-74 years), and the median ECOG performance status was 1 (0-1, 61 (95%)). Out of 64 patients, 57 were assessable for response. Among 57 assessable patients, no complete response and 12 partial responses were observed (overall response rate, 21%; 95% confidence interval (CI), 10-32%). Stable disease was observed in 14 patients (25%) and progressive disease in 31 patients (54%). The median time to progression was 2.5 months (95% CI, 1.6-3.4) and the median overall survival since the start of the second-line modified FOLFIRI was 7.6 months (95% CI, 6.5-8.7). Grade 3-4 haematologic toxicities included neutropenia in seven patients (11%) and thrombocytopenia in five patients (8%). Grade 3-4 nonhaematologic toxicities included diarrhoea in two patients (3%) and vomiting in two patients (3%). There were no treatment-related deaths. The combination of irinotecan, 5-FU and leucovorin showed moderate activity and favourable toxicity profile as a second-line treatment in metastatic gastric cancer patients, who were previously treated with taxane and cisplatin.

Adenocarcinoma↗