Biomedical subjects

S H Lee

Publications and source records attributed to S H Lee.

At least 73 records · Page 4Linked to original sources

PubMed2005

Atomic-scale visualization of inertial dynamics.

The motion of atoms on interatomic potential energy surfaces is fundamental to the dynamics of liquids and solids. An accelerator-based source of femtosecond x-ray pulses allowed us to follow directly atomic displacements on an optically modified energy landscape, leading eventually to the transition from crystalline solid to disordered liquid. We show that, to first order in time, the dynamics are inertial, and we place constraints on the shape and curvature of the transition-state potential energy surface. Our measurements point toward analogies between this nonequilibrium phase transition and the short-time dynamics intrinsic to equilibrium liquids.

Journal Article↗

PubMed2005

Observation of an isotriplet of excited charmed baryons decaying to lambda+c pi.

We report the observation of an isotriplet of excited charmed baryons, decaying into Lambda(+)(c)pi(-), Lambda(+)(c)pi(0), and Lambda(+)(c)pi(+). We measure the mass differences M(Lambda(+)(c)pi)-M(Lambda(+)(c)) and widths to be 515.4(+3.2+2.1)(-3.1-6.0) MeV/c(2), 61(+18+22)(-13-13) MeV for the neutral state; 505.4(+5.8+12.4)(-4.6-2.0) MeV/c(2), 62(+37+52)(-23-38) MeV for the charged state; and 514.5(+3.4+2.8)(-3.1-4.9) MeV/c(2), 75(+18+12)(-13-11) MeV for the doubly charged state, where the uncertainties are statistical and systematic, respectively. These results are obtained from a 281 fb(-1) data sample collected with the Belle detector near the Upsilon(4S) resonance, at the KEKB asymmetric energy e(+)e(-) collider.

Journal Article↗

PubMed2005

Observation of B+-->K1(1270)+gamma.

We report the observation of the radiative decay B+-->K1(1270)(+) gamma using a data sample of 140 fb(-1) taken at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. We find the branching fraction to be B(B+-->K1(1270)(+)gamma)=(4.3+/-0.9(stat.)+/-0.9(syst.))x10(-5) with a significance of 7.3sigma. We find no significant signal for B+-->K1(1400)(+)gamma and set an upper limit B(B+-->K1(1400)(+)gamma)<1.5 x 10(-5) at the 90% confidence level. We also measure inclusive branching fractions for B+-->K+pi+pi-gamma and B0-->K0pi+pi-gamma in the mass range 1 GeV/c(2)<M(K+(0)pi+pi-)<2 GeV/c(2).

Journal Article↗

PubMed2005

Clocking femtosecond X rays.

Linear-accelerator-based sources will revolutionize ultrafast x-ray science due to their unprecedented brightness and short pulse duration. However, time-resolved studies at the resolution of the x-ray pulse duration are hampered by the inability to precisely synchronize an external laser to the accelerator. At the Sub-Picosecond Pulse Source at the Stanford Linear-Accelerator Center we solved this problem by measuring the arrival time of each high energy electron bunch with electro-optic sampling. This measurement indirectly determined the arrival time of each x-ray pulse relative to an external pump laser pulse with a time resolution of better than 60 fs rms.

Journal Article↗

PubMed2005

Search for D0-D0 mixing in D0 --> K+ pi(-) decays and measurement of the doubly-Cabibbo-suppressed decay rate.

We have searched for mixing in the D(0)-D (0) system by measuring the decay-time distribution of D(0) --> K(+) pi(-) decays. The analysis uses 90 fb(-1) of data collected by the Belle detector at the KEKB e(+) e(-) collider. We fit the decay-time distribution for the mixing parameters x' and y' and also for the parameter R(D), which is the ratio of the rate for the doubly-Cabibbo-suppressed decay D(0)--> K+ pi(-) to that for the Cabibbo-favored decay D(0)--> K-pi(+). We do these fits both assuming CP conservation and allowing for CP violation. We use a frequentist method to obtain a 95% C.L. region in the x'(2) - y' plane. Assuming no mixing, we measure R(D) = (0.381 +/- 0.017(+0.008)(-0.016))%.

Journal Article↗

PubMed2005

Observation of B0-->D*sJ(2317)+K- decay.

The decays B0-->D+sJK- and B0-->D-sJpi+ are studied for the first time. A significant signal is observed in the B0-->D*sJ(2317)+K- decay channel with B(B0-->D*sJ(2317)+K-) x B(D*sJ(2317)+-->D+spi0)=(5.3(+1.5)(-1.3)+/-0.7+/-1.4) x 10(-5). No signals are observed in the B0-->D*sJ(2317)-pi+, B0-->DsJ(2460)+K-, and B 0-->DsJ(2460)-pi+ decay modes, and upper limits are obtained. The analysis is based on a data set of 140 fb(-1) collected by the Belle experiment at the asymmetric e+e- collider KEKB.

Journal Article↗

PubMed2005

p66Shc expression in proliferating thyroid cells is regulated by thyrotropin receptor signaling.

It is almost unanimously accepted that thyrocyte proliferation is synergistically activated by TSH and insulin/IGF-I. Moreover, it was recently suggested that p66Shc, which is an adaptor molecule of the IGF-I receptor, might play a critical role in this synergistic effect. In this study, we undertook to confirm the role and the mechanism underlying the regulation of p66Shc expression via TSH receptor in thyrocytes. We have found that p66Shc expression is elevated in proliferating human thyroid tissues, including adenomatous goiter, adenoma, Graves' disease, and thyroid cancer, but not in normal thyroid. Among growth factors, TSH increased p66Shc expression both in vivo and in vitro; however, IGF-I, epidermal growth factor, or insulin did not. TSH and Graves' Ig increased the p66Shc expression via the TSH receptor-G(s)-cAMP pathway. However, interestingly, IGF-I or epidermal growth factor increased the tyrosine phosphorylations of p66Shc, and this was enhanced by TSH pretreatment. A similar synergism was observed during the DNA synthesis. When we measured the p66Shc levels induced by individual Igs from 130 patients with Graves' disease, TSH receptor stimulating activity and goiter size showed a weak correlation. We conclude that the expression of p66Shc is regulated by signaling through the TSH receptor in proliferating thyroid cells and that p66Shc appears to be an important mediator of the synergistic effect between TSH and IGF-I with respect to thyrocyte proliferation. Moreover, we suggest that TSH potentiates the regulatory effect of IGF-I on thyrocyte growth, at least in part, by increasing the expression of p66Shc.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Two formulations of the industrial surfactant, Toximul, differentially reduce mouse weight gain and hepatic glycogen in vivo during early development: effects of exposure to Influenza B Virus.

Previous studies demonstrated that young mice exposed chronically to industrial surfactant (IS) do not exhibit obvious adverse health effects, but do have persistently reduced body weights and compromised hepatic energy metabolism. The present study examined the time course of effects of two formulations of the Toximul (Tox) class of anionic/nonionic IS on body weights and liver glycogen (+/-virus) during early development. Results showed that effects differed in two commonly used strains of mice. In CFW mice, 12 days' exposure to Tox resulted in retardation of weight gain that was most obvious several days after exposure ceased. In this strain effects were greater with Tox 3409F than with Tox MP-A and appeared to be reversible except when the mice were treated with both Tox 3409F and FluB. Weights of the CD-1 mice were not affected by either Tox treatment alone, but were significantly reduced on postnatal day 20 when Tox exposure had been combined with FluB infection. Postnatal replenishment of hepatic glycogen stores during the first three weeks also occurred at different rates in CFW and CD-1 mice. The effects of Tox (+/-FluB) on glycogen also varied with mouse strain and Tox formulation. In CFW mice, exposure to either formulation resulted in significant (55-59%) reductions in glycogen, although reductions were not evident until nine days after Tox exposure stopped. By contrast, hepatic glycogen in CD-1 mice was reduced both during and after dermal exposure to Tox 3409F, whereas no effect was observed with Tox MP-A. Notably, the 3409F effect was reversible in the CD-1 mice, but reversal did not occur in mice also infected with FluB. Tox MP-A+FluB-treated mice exhibited only a transient glycogen reduction. These results illustrate the importance of mouse strain and formulation specificities in assessing biological effects of xenobiotic surfactants. As well, they emphasize that chronic IS exposure can induce changes in growth and energy substrate availability in young mice that may not be evident unless there is a precipitating cofactor such as a viral infection.

Animals↗

PubMed2005

An easily integrative and efficient micromixer and its application to the spectroscopic detection of glucose-catalyst reactions.

The focus of this paper is on the fabrication of a PDMS-based passive efficient micromixer to be easily integrated into the other on-chip microfluidic system. The mixing is achieved by "strong stretching and folding," which employs a three-dimensional microchannel structure. By the simultaneously vertical and transversal dispersion of fluids, strong advection is developed. Owing to this powerful mixing performance (more than 70% of the mixing is accomplished within 2.3 mm over a wide range of Reynold number (Re)), the smaller integrative mixer can be realized. The feasibility and the potential usefulness of an integrative micromixer were evaluated by incorporating two mixers into the microchannel for the spectroscopic detection of a glucose-catalyst reaction. The results demonstrate a promising performance for diverse applications in the assay or synthesis of biological or chemical materials.

Biosensing Techniques↗

PubMed2005

Measurement of the branching fraction and CP asymmetry in B+ --> rho+pi0.

We report a measurement of the branching fraction for the decay B+ --> rho(+) pi(0) based on a 140 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric e(+)e(-) collider. We measure the branching fraction B(B(+) --> rho(+)pi(0)) = (13.2 +/- 2.3(stat)(+1.4)(-1.9)(syst)) x 10(-6), and the CP-violating asymmetry A(CP)(B-/+ -->rho(-/+)pi(0))=0.06 +/- 0.17(stat)(+0.04)(-0.05)(syst).

Journal Article↗

PubMed2005

Evidence for the importance of extracranial venous flow in patients with idiopathic intracranial hypertension (IIH).

Idiopathic intracranial hypertension (IIH) is characterized by increased ICP without evidence for intracranial mass lesion. Although the pathogenesis remains unknown, some association was found with intracranial venous thrombosis. To our knowledge, the extracranial venous drainage was not systematically evaluated in these patients. This study compared extracranial cerebral venous outflow in eight IIH patients and eight control subjects using magnetic resonance (MR) Venography and flow measurements. In addition, the study identified extracranial factors that affect cerebral venous drainage. In six of the IIH patients, either complete or partial functional obstruction of the internal jugular veins (IJVs) coupled with increased venous outflow through secondary venous channels was documented. On average, a four-fold increase in mean venous flow rate through the epidural and/or vertebral veins was measured in IIH patients compared with the healthy subjects. In one of the healthy subjects, intracranial venous outflow was studied also during external compression of the IJVs. Over 40% of the venous outflow through the IJVs shifted to the epidural veins and intracranial pressure, measured noninvasively by MRI, increased from 7.5 to 13 mmHg. Findings from this study suggest that increased ICP in some IIH patients could be associated with increased extracranial resistance to cerebral venous outflow.

Adult↗

PubMed2005

MRI study of cerebral blood flow and CSF flow dynamics in an upright posture: the effect of posture on the intracranial compliance and pressure.

Postural related changes in cerebral hemodynamics and hydrodynamics were studied using Magnetic Resonance Imaging (MRI) measurements of cerebral blood flow and cerebrospinal fluid (CSF) flow dynamics. Ten healthy volunteers (mean age 29 +/- 7) were studied in supine and upright (sitting) postures. A Cine phase-contrast MRI technique was used to image the pulsatile blood flow to the brain, the venous outflow through the internal jugular, epidural, and vertebral veins, and the bi-directional CSF flow between the cranium and the spinal canal. Previously published analyses were applied to calculate and compare total cerebral blood flow (TCBF), intracranial compliance and pressure in both postures. A lower (12%) mean TCBF was measured in the upright position compared to supine position. A considerable smaller amount of CSF flow between the cranium and the spinal canal (58%), a much larger intracranial compliance (a 2.8-fold increase), and a corresponding decrease in the MRI-derived ICP were also measured in the sitting position. These changes suggest that the increased cerebrovascular and intracranial compliances in the upright posture are primarily due to reduced amounts of blood and CSF residing in their respective intracranial compartments in the upright position. This work demonstrates the ability to quantify neurophysiologic parameters associated with regulation of cerebral hemodynamics and hydrodynamics from dynamic MR imaging of blood and CSF flows.

Adaptation, Physiological↗

PubMed2005

Relationship between total cerebral blood flow and ICP measured noninvasively with dynamic MRI technique in healthy subjects.

Cerebral blood flow and ICP are important neurophysiologic parameters known to be affected by pathology and by trauma. Limited data on the relationship between these parameters following head trauma is inconsistent with regard to whether these parameters are correlated. Data on the relationship between these parameters in the healthy state is not readily available due to a lack of noninvasive means to measure these important parameters. A recently developed noninvasive MRI-based method for simultaneous measurement of total cerebral blood flow and intracranial pressure was applied to establish the relationship between ICP and TCBF values in healthy subjects. Seventy-one simultaneous measurements of CBF and ICP were obtained from 23 healthy young adults. These results demonstrated that CBF values span over a much narrower range compared with ICP. The relationship between the inter-individual CBF and ICP measurements suggest that in the healthy state and in rest these parameters are not correlated.

Adult↗

PubMed2005

Conidia production by Beauveria bassiana (for the biocontrol of a diamondback moth) during solid-state fermentation in a packed-bed bioreactor.

Conidia of Beauveria bassiana CS-1, which have the potential for the control of the diamondback moth (Plutella xylostella), were produced by solid-state fermentation (SSF) using a packed-bed bioreactor with rice straw and wheat bran. As the packing density and the bed height were increased, the production of conidia decreased. In a packed-bed bioreactor under no aeration and no addition of polypropylene (PP) foam (control), the total average of conidia was 4.9 x 10(8) g-1. The production of conidia was affected more by the addition of PP foam as an inert support than forced aeration and was approx. 23 times higher than that of the control. The total average of conidia produced by B. bassiana was 1.1-1.2 x 10(10) g-1 .

Air↗

PubMed2005

Effects of teat number on litter size in gilts.

This study was carried out to investigate the effects of teat number and interval at first estrus and mating on litter size in Duroc, Landrace and Yorkshire gilts. Gilt body weight at first estrus was from 101.5 kg to 115.3 kg and gilts normally attained puberty at 170.5-181.5 days of age. Breed differences among Duroc, Landrace and Yorkshire in body weight and age at first estrus and mating were found. Total teat number of Duroc, Landrace and Yorkshire were 12.5, 14.9 and 13.7, respectively. Teat interval from pectoral to inguinal region and from left to right at first estrus and mating did not show any differences among the breeds. In conclusion, 14 or more teat number compared to 11-13 teat number in gilts increased litter size at birth and at 21 day weaning.

Aging↗

PubMed2005

Preliminary results of consolidation chemotherapy following concurrent chemoradiation after radical surgery in high-risk early-stage carcinoma of the uterine cervix.

AIMS: To evaluate the efficacy and toxicity of consolidation chemotherapy after concurrent chemoradiation (CCRT) with 5-fluorouracil (5-FU) and cisplatin in the treatment of high-risk, early stage cervical carcinoma after radical surgery. MATERIALS AND METHODS: Women with clinical stage IB and IIA cervical carcinoma, initially treated with radical hysterectomy and pelvic lymphadenectomy, and who had positive pelvic lymph nodes, positive margins, parametrial involvement, or all three, were divided into either a CCRT alone group or a consolidation chemotherapy after CCRT group. Three cycles of chemotherapy were given to the CCRT alone group, and six cycles to the consolidation chemotherapy group. Women in each group received 50.4 Gy external radiation in 28 fractions to a standard pelvic field. Chemotherapy consisted of cisplatin 60 mg/m2 (X 1) and 5-FU 1000 mg/m2/d (X 5) every 3 weeks, with the first and second cycles given concurrent with radiation. Survival and toxicity were compared between the two groups. RESULTS: Forty women were evaluable (25 in the CCRT alone group and 15 in the consolidation chemotherapy group). The estimated 2-year progression-free survival was 87.7% in the CCRT alone group and 67.0% in the consolidation chemotherapy group. The estimated 2-year overall survival was 95.8% in the CCRT alone group and 100% in the consolidation chemotherapy group. However, no significant differences were found in progression-free and overall survival in the two groups (P = 0.17 and P = 0.29, respectively). Grade 2 or higher leukopenia and neutropenia were significantly more frequent in the consolidation chemotherapy group than in the CCRT alone group (P = 0.02 and P < 0.01, respectively). CONCLUSIONS: Although the sample size was small, and this study was not randomised, these results suggest that consolidation chemotherapy may not improve survival. Rather, it may increase haematologic toxicities for women with high-risk, early stage cervical carcinoma who undergo radical surgery followed by CCRT.

Adenocarcinoma↗

PubMed2005

Depressive symptoms of type 2 diabetics treated with insulin compared to diabetics taking oral anti-diabetic drugs: a Korean study.

OBJECTIVE: The purpose of this study was to examine the depressive symptoms of type 2 diabetic patients who were treated with insulin compared to those diabetics treated with oral anti-diabetic drugs in Korea. METHODS: A total 204 outpatients with type 2 diabetes were invited to complete a questionnaire using the Beck depression inventory (BDI) to measure depressive symptoms. Age, gender, body mass index, serum lipid profile, and a social history including marital status, occupation and educational background were also assessed. The presence of diabetic complications was evaluated by examining the patients' medical records. Diabetic patients who were not treated with anti-diabetic drugs were excluded. All the study subjects were classified into two groups based on their mode of therapy: the oral drug group and insulin group. The insulin group included patients treated with insulin-oral drug combinations as well as those treated solely with insulin. RESULTS: Overall, 32.4% of our diabetic subjects showed depressive symptoms with the criterion being a BDI score > or = 16. Compared to the oral drug group, the insulin group showed a significantly higher frequency of depressive symptoms (insulin group, 48.0%; oral drug group, 27.3%; p<0.01) and higher BDI scores (insulin group, 16.6+/-10.7; oral drug group, 12.6+/-8.7; p<0.01). Moreover, after an adjustment for social factors, the degree of hyperglycemia and the presence of diabetic complications, the insulin group showed a significantly higher frequency of depression (odds ratio 4.38, 95% CI 1.66-11.6, p=0.003), compared to the oral drug group. CONCLUSIONS: The data showed that insulin treatment is related to the presence of depressive symptoms, and the importance of more careful psychological support of Korean insulin-treated type 2 diabetic patients is strongly suggested.

Administration, Oral↗

PubMed2005

Investigation of a nosocomial outbreak of Acinetobacter baumannii producing PER-1 extended-spectrum beta-lactamase in an intensive care unit.

We investigated an outbreak of Acinetobacter baumannii in an adult intensive care unit of Kosin University Gospel Hospital in Busan, Republic of Korea. The outbreak involved 10 cases of infection by A. baumannii producing PER-1 extended-spectrum beta-lactamase over a seven-month period, and was caused by a single pulsed-field gel electrophoresis clone. The epidemic isolates were characterized by slight synergy between clavulanic acid and cefepime. Isoelectric focusing of crude bacterial extracts detected two nitrocefin-positive bands with pI values of 8.0 and 5.3. Polymerase chain reaction amplification and characterization of the amplicons by restriction analysis and direct sequencing indicated that the epidemic isolates carried a bla(PER-1) determinant. The epidemic isolates were characterized by a multidrug-resistant phenotype that remained unchanged over the outbreak, including penicillins, beta-lactam/beta-lactamase inhibitor, extended-spectrum cephalosporins and monobactams. Isolation of infected patients and appropriate carbapenem therapy were successful in ending the outbreak. Our report indicates that the bla(PER-1) resistance determinant may become an emerging therapeutic problem.

Acinetobacter Infections↗