Search PubMed⌕ Search

Biomedical subjects

K Cho

Publications and source records attributed to K Cho.

At least 19 recordsLinked to original sources
PubMed2002

A high statistics measurement of the Lambda(+)(c) lifetime.

A high statistics measurement of the Lambda(+)(c) lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat) +/- 2.5 (syst) fs from 8034 +/- 122 Lambda(+)(c)-->pK(-)pi(+) decays represents a significant improvement over the present world average.

Journal Article↗
PubMed2002

Search for CP violation in the decays D+--> K(S)pi+ and D+-->K(S)K+.

A high-statistics sample of photoproduced charm from the FOCUS experiment has been used to search for direct CP violation in the decay rates for D+-->K(S)pi+ and D+-->K(S)K+. We have measured the following asymmetry parameters relative to D+-->K-pi+pi+: A(CP)(K(S)pi+) = (-1.6+/-1.5+/-0.9)%, A(CP)(K(S)K+) = (+6.9+/-6.0+/-1.5)%, and A(CP)(K(S)K+) = (+7.1+/-6.1+/-1.2)% relative to D+-->K(S)pi+. We have also measured the relative branching ratios and found Gamma(D+-->K(0)pi+)/Gamma(D+-->K-pi+pi+) = (30.60+/-0.46+/-0.32)%, Gamma(D+-->K(0)K+)/Gamma(D+-->K-pi+pi+) = (6.04+/-0.35+/-0.30)%, and Gamma(D+-->K(0)K+)/Gamma(D+-->K(0)pi+) = (19.96+/-1.19+/-0.96)%.

Journal Article↗
PubMed2001

Measurement of the branching ratios of D(+) and D(+)(s) hadronic decays to four-body final states containing a K(S).

We have studied hadronic four-body decays of D(+) and D(+)(s) mesons with a K(S) in the final state using data recorded during the 1996-1997 fixed-target run of the Fermilab high energy photoproduction experiment FOCUS. We report a new branching ratio measurement of gamma(D(+)-->K(S)K-pi(+)pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0768+/-0.0041+/-0.0032. We make the first observation of three new decay modes with branching ratios gamma(D(+)-->K(S)K+pi(+)pi(-))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0562+/-0.0039+/-0.0040, gamma(D(+)-->K(S)K+K-pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0077+/-0.0015+/-0.0009, and gamma(D(+)(s)-->K(S)K+pi(+)pi(-))/gamma(D(+)(s)-->K(S)K-pi(+)pi(+)) = 0.586+/-0.052+/-0.043, where in each case the first error is statistical and the second error is systematic.

Journal Article↗
PubMed2001

Parallel self-induction of TNF-alpha and apoptosis in the thymus of mice after burn injury.

BACKGROUND: Burn injury often causes multiple organ failure as well as skin damage. Several studies suggest that TNF-alpha plays an important role in postinjury immunosuppression by altering lymphoid tissues. We investigated the regulation of TNF-alpha expression and apoptosis in the spleen and thymus of mice after burn injury. MATERIALS AND METHODS: C57BLKS/J mice were subjected to 18% TBSA full-thickness burn and the spleen and thymus were harvested at various time points (3 h to 29 days). The expression of TNF-alpha mRNA and protein in tissue extracts was analyzed by RT-PCR and ELISA. Apoptosis was measured by flow cytometry using annexin V staining. RESULTS: Burn injury induced TNF-alpha mRNA expression in the thymus at Day 1 and it returned to the basal levels at Day 14 and thereafter. Similarly, TNF-alpha mRNA up-regulation peaked between Day 1 and Day 3 in the spleen. Induction of TNF-alpha protein peaked at Day 1 in the thymus, whereas, TNF-alpha protein was unchanged in the spleen after burn injury. There was a twofold increase in apoptotic cells at Day 1 in the thymus, which is consistent with mRNA and protein data. In contrast, burn injury did not change apoptotic events in the spleen. CONCLUSIONS: The parallel induction of TNF-alpha mRNA, TNF-alpha protein, and apoptosis suggests that TNF-alpha may contribute to immunosuppression after burn injury by inducing apoptosis in the thymus.

Animals↗
PubMed2001

An experimental test of the role of postsynaptic calcium levels in determining synaptic strength using perirhinal cortex of rat.

1. We have investigated the prediction of a relationship between the magnitude of activity-dependent increases in postsynaptic calcium and both the magnitude and direction of synaptic plastic change in the central nervous system. 2. Activity-dependent increases in calcium were buffered to differing degrees using a range of concentrations of EGTA and the effects on synaptic plasticity were assessed. Activity-dependent synaptic plasticity was induced during whole-cell recording in rat perirhinal cortex in vitro. In control conditions (0.5 mM EGTA) low frequency stimulation (LFS; 200 stimuli) delivered to neurones held at -40 or -70 mV induced long-term depression (LTD) or, at -10 mV, induced long-term potentiation (LTP). 3. The relationship between EGTA concentration (0.2 to 10 mM) and the magnitude of LTD was examined. This relationship described a U-shaped curve, as predicted by models of synaptic plasticity. This provides strong evidence that the magnitude of LTD is determined by the magnitude of the increase in intracellular calcium concentration. 4. LFS paired with depolarisation to -10 mV induced LTD, no change or LTP as activity-dependent postsynaptic calcium levels were allowed to increase progressively by the use of progressively lower concentrations of buffer (10 to 0.2 mM EGTA). 5. We investigated if the lack of plasticity that occurs at the transition between LTD and LTP is due to induction of both of these processes with zero net change, or is due to neither LTD nor LTP being induced. These experiments were possible as LTP but not LTD was blocked by the protein kinase inhibitor staurosporine while LTD but not LTP was blocked by the mGlu receptor antagonist MCPG. At the transition between LTD and LTP, blocking LTP mechanisms did not uncover LTD whilst blocking LTD mechanisms did not uncover LTP. This suggests that the transition between LTD and LTP is due to the lack of induction of both of these processes and also suggests that these two processes are induced independently of one another.

Animals↗
PubMed2001

Study of the decay D0 --> K+pi-.

Using a large sample of photoproduced charm mesons from the FOCUS experiment at Fermilab (FNAL-E831), we observe the decay D0-->K+pi- with a signal yield of 149+/-31 events compared to a similarly cut sample consisting of 36 760+/-195 D0-->K-pi+ events. We use the observed ratio of D0-->K+pi- to D0-->K-pi+ (0.404+/-0.085+/-0.025)% to obtain a relationship between the D0 mixing and doubly Cabibbo suppressed decay parameters.

Journal Article↗
PubMed2001

Correlation between genotype and phenotype in Korean patients with spinal muscular atrophy.

The goal of this study was to define the correlation between genotype and phenotype in Korean patients with spinal muscular atrophy (SMA). The SMA can be classified into three groups based on the age of onset and the clinical course. The candidate genes, survival motor neuron (SMN) gene, neuronal apoptosis inhibitory protein (NAIP) gene, and p44 gene were mapped and duplicated with telomeric and centromeric. The loss of the telomeric SMN occurs by a different mechanism. That is the deletion or conversion of telomeric SMN to centromeric SMN, in which case the conversion could produce a mild phenotype and deletion could produce a severe one. It has been known that there may be a balance between the numbers of copies expressed by the centromeric and telomeric SMN genes. In our study, ten patients with type I SMA and two type II patients were identified by their clinical findings and DNA studies. The major deletion of SMA candidate genes, deletion of the SMN gene, NAIP gene, and p44 gene were identified in six patients with type I SMA, while the rest of type I and all the type II patients showed the deletion of the SMN gene only. Allele numbers of the C212 marker were compared in patients and normal controls in order to find the correlation between the copy numbers and the clinical severity. The result was that type I patients had 2-5 alleles and the normal controls had 4-6. This suggests that the deletion is a major determining factor in the clinical phenotype. However, two type I patients with telomeric NAIP gene deletion notably had 4-5 alleles, as in the normal controls. This result implies that the correlation between the copy numbers and the severity is uncertain as opposed to the previous hypothesis. One type I patient showed the conversion of the centromeric SMN gene to the telomeric, which supports the conclusion that gene conversion is an important molecular mechanism for SMA. In the study of one hundred normal newborns, two physically normal newborns showed deletion of the centromeric SMN gene, suggesting frequent rearrangement in the locus.

Child↗
PubMed2001

Prenatal diagnosis of agnathia-holoprosencephaly: three-dimensional imaging by helical computed tomography.

We report a case of agnathia-holoprosencephaly which was prenatally diagnosed based on helical computed tomography (CT) images obtained at 23 weeks of gestation. Ultrasound examination first showed the presence of alobar holoprosencephaly, but the facial structures were not clearly detailed. However, three-dimensional imaging by helical CT precisely demonstrated the most striking feature of agnathia: absence of the mandible. This technique provided us valuable information that contributed to the in utero diagnosis. In utero helical CT is a useful examination tool for the diagnosis of osteogenic abnormalities.

Adult↗
PubMed2001

Examination of intra-gastrointestinal tract signal elimination in MRCP: combined use of T(1)-shortening positive contrast agent and single-shot fast inversion recovery.

To examine the effects of removing the gastrointestinal signal in MR cholangiopancreatography (MRCP), investigations were carried out on the combined use of T(1)-shortening intestine-positive contrast medium, FerriSeltz with ferric ammonium citrate as the main component, and high-speed imaging using single-shot fast inversion recovery (SSFIR). The contrast effect was significantly elevated to 10.2 +/- 1.6 after administration, compared with 5.9 +/- 2.4 before administration (P < 0.001). The enhancement effect was also significantly elevated to 13.2 +/- 3.0 after administration, compared with 4.9 +/- 3.1 before administration (P < 0.001). These results were obtained because the null point of FerriSeltz aqueous solution (5.97 mmol/L) was in the range of approximately 180 msec. With the present method, adequate suppression of the signal intensity of the digestive tract was obtained relatively easily with MRCP, and the technique was found to be effective. J. Magn. Reson. Imaging 2001;13:738-743.

Adult↗
PubMed2001

Structural determination of lysophosphatidylcholines extracted from marine sponges by fast atom bombardment tandem mass spectrometry.

A series of lysophosphatidylcholines were isolated from the marine sponge Spirastrella abata by reversed-phase high performance liquid chromatography (HPLC) and analyzed by fast atom bombardment mass spectrometry (FAB-MS). Their structural elucidation was carried out with fast atom bombardment tandem mass spectrometry (FAB-MS/MS). The collision-induced dissociation (CID) of protonated and sodiated molecular ions produced diverse product ions via a series of dissociative processes. Because of the positive charge of the amine group at the end of the molecules, charge-remote fragmentation patterns of specific ions, [M + H](+) or [M + Na](+), were very helpful for the identification of product ions which are characteristic for choline and long hydrocarbon chains substituted at the glycerol back bone. Moreover, the CID-MS/MS spectra of sodium adducted molecular ions for lysophosphatidylcholines yielded common characteristic fragment ions for the choline moiety and characteristic ions [M + Na-103](+), [M + Na-85](+) and [M + Na-59](+) in the higher mass region.

Animals↗
PubMed2001

Identification of four novel mutations in classical Menkes disease and successful prenatal DNA diagnosis.

Menkes disease is an X-linked recessive disorder of the copper metabolism and affected males suffer a systemic copper deficiency due to malabsorption and defective distribution of dietary copper. It is caused by a defect in the Menkes (ATP7A) gene, which encodes a transmembrane copper-transporting P-type ATPase. A variety of mutations were reported; however, only a few mutations were reported in Asian patients. We identified four novel mutations and one known mutation in five Korean patients. Arg646Ter in exon 8, a novel mutation transmitted from his carrier mother, was identified in one patient. Prenatal DNA diagnosis on an unaffected fetus in this carrier mother was successfully accomplished. An additional three novel mutations, Leu706Arg in exon 9, Gly1118Asp in exon 17, and Gly1255Arg in exon 19, were identified. Splicing mutation was not identified. Menkes disease in Korean patients appears to be caused by heterogeneous mutations with different spectrums from Caucasian patients.

Adenosine Triphosphatases↗
PubMed2001

Massive intravenous immunoglobulin treatment in pregnancy complicated by Guillain-Barré Syndrome.

A pregnant woman developed acute demyelinating poly-neuropathy (Guillain-Barré syndrome (GBS)) in the 28th week of gestation (GW) after flu-like infection. Hypertension, liver dysfunction, and a decrease in consciousness level developed at 29GW. Blood chemical analysis revealed increased levels of liver enzymes GOT 247 IU/l and GPT 624 IU/l. Viral serological study showed a positive test for Epstein-Barr virus IgM. Weakness of bilateral facial muscles and limbs, a loss of tendon reflexes, and generalized paresthesia were detected by neurologic examinations. Over the course of 5 days, a massive dose (100g) of intravenous immunoglobulin (MIVIg) was infused in 30GW. An average manual muscle testing score by the Medical Research Council method and peak flow value began to be significantly restored during and after MIVIg infusions. Values of the liver enzymes gradually decreased, and improvement of the muscle weakness and dysbasia was observed. Her pregnancy normally ended in spontaneous vaginal delivery of a healthy infant in 37GW. This is the first report confirming the efficacy of MIVIg, without plasmapheresis, in GBS-complicated pregnancy.

Adult↗
PubMed2001

Activation of muscarinic receptors induces protein synthesis-dependent long-lasting depression in the perirhinal cortex.

There is strong evidence that decrements in neuronal activation in perirhinal cortex when a novel stimulus is repeated provide a neural substrate of visual recognition memory. There is also strong evidence that muscarinic acetylcholine (ACh) receptors are involved in learning and memory. However, the mechanisms underlying neuronal decrements in the perirhinal cortex and the basis of ACh involvement in learning and memory are not understood. In an in vitro preparation of rat perirhinal cortex we now demonstrate that activation of ACh receptors by carbachol (CCh) produces long-lasting depression (LLD) of synaptic transmission that is dependent on muscarinic M1 receptor activation. Crucially, the induction of this form of LLD requires neither N-methyl-D-aspartate receptor activation nor synaptic stimulation. CCh-induced LLD was not blocked by the protein kinase C inhibitors staurosporine or BIM, or by the protein phosphatase inhibitor okadaic acid. However, each of cyclopiazonic acid (an agent that depletes intracellular calcium stores) and anisomycin (an inhibitor of protein synthesis) significantly reduced the magnitude of CCh-induced LLD. These mechanisms triggered by muscarinic receptor activation could play a role in the induction and/or expression of certain forms of activity-dependent long-term depression in perirhinal cortex. An understanding of CCh-induced LLD may thus provide clues to the mechanisms underlying lasting neuronal decrements that occur in the perirhinal cortex and hence for neural substrates of visual recognition memory.

Acetylcholine↗
PubMed2001

Antenatal dexamethasone administration impairs normal postnatal lung growth in rats.

Our purpose was to determine the influences of antenatal dexamethasone administration on neonatal lung development in rats. Dexamethasone (0.4 mg/kg maternal body weight per day) was administered i.p. on the 21st d (group 1) or on the 20th and 21st d (group 2) of gestation in Sprague Dawley rats with timed pregnancies. After natural deliveries, the lungs of the pups 1-60 d of age were removed and processed for morphometric analysis. In 60-d-old pups, groups 1 and 2 both showed a lower numerical density of alveoli and a larger mean alveolar radius than control pups. Antenatal administration of dexamethasone to rats impairs the normal postnatal lung growth. Some aspects of the use of antenatal glucocorticoid therapy in humans may require reconsideration.

Animals↗
PubMed2001

Teleradiology in a military training area.

A pilot teleradiology project was established for the medical service providers at the Pohakuloa Training Area (PTA) in Hawaii. It connected them with radiologists at Tripler Army Medical Center (TAMC) on the island of Oahu, approximately 400 km away. This involved changing the standard practice of sending soldiers from the PTA to a civilian hospital in Hilo for radiographs. These emergency trips to Hilo, 55 km away, were expensive, manpower intensive, and dangerous due to road and weather conditions. During 51 days of a training exercise involving 2600 personnel, 29 evacuations were avoided, which would have cost $36,569 in total. The expected savings during one year of training were $176,540. The cost of teleradiology during the first year, including the cost of the equipment, was $167,203. Over five years, the costs and savings were estimated to be $349,940 and $882,700, respectively.

Hawaii↗
PubMed2001

[Assessment of left ventricular function with the solid-state digirad 2020tc Imager].

Multigated equilibrium radionuclide ventriculography from best septal position (LAO view) was performed in 17 patients with cardiac disease with a single detector Anger-type gamma camera (GCA 602A, Toshiba), then immediately imaged with a solid-state, multi-crystal gamma camera (Digirad 2020tc Imager). Acquisition times were the same of 10 minutes. The solid-state gamma camera uses CsI(Tl) as the scintillation material and a Si photodiode. CsI(Tl) has a higher density and higher atomic number than NaI(Tl), so that its efficiency for detecting gamma rays is higher. To confirm this, total acquisition counts in 17 patients obtained from the 2020tc Imager were significantly higher than those obtained from the Anger-type camera (7847 +/- 2061 K vs. 4427 +/- 1162 K counts, p < 0.0001). In comparing left ventricular ejection fractions obtained from the Anger-type camera and the 2020tc Imager data, an excellent correlation was revealed with a correlation coefficient of 0.97 (p < 0.0001). Again, peak ejection rate and peak filling rate obtained from the 2020tc Imager data correlated well with those obtained from the Anger-type camera data (r = 0.93, p < 0.0001 and r = 0.80, p < 0.001, respectively). These data reveal that the 2020tc Imager has an excellent data collection efficiency and a high reliability in assessment of left ventricular function. Thus, the solid-state gamma camera was thought to be a useful hardware in nuclear cardiology.

Aged↗
PubMed2001

[Examination concerning dissociation of left ventricular volume calculation value based on difference of analytical algorithm and perfusion tracer in gated myocardial SPECT].

According to improvement of SPECT system, ECG-gated SPECT with 201TlCl have been applied to the left ventricular volumetry. In this study 24 patients without ischemia demonstrated by stress (99mTc-TF) and rest (201TlCl) dual-isotope ECG-gated myocardial SPECT were enrolled. To evaluate left ventricular volumetry using 201Tl ECG-gated SPECT data, the left ventricular end diastolic volumes (EDV) were compared between Quantitative Gated SPECT (QGS) and Emory Cardiac Toolbox (ECT) as well as between dual-isotopes based on the same ECG-gated data. The EDV values with 99mTc data (EDVTc) using QGS were well correlated with those using ECT (r = 0.96, p < 0.0001). Both QGS and ECT demonstrated well correlation between EDVTc (r = 0.98, p < 0.0001) and the EDV value with 201Tl (EDVTl) (r = 0.93, p < 0.0001). However, QGS processing induced significantly lower EDVTl compared with EDVTc. In contrast, EDVTl were significantly higher than EDVTc in ECT performance. The QGS errors subtracting EDVTl from EDVTc were more evident according to the left ventricular volume increase. On the other hand, ECT error showed no tendency associated with the left ventricular volume. From these results, a careful strategy for selection of tracers and softwares should be necessary to assessment of quantitative values derived from ECG-gated SPECT data because of interaction with softwares, tracers, and subjects.

Adult↗