141 research outputs found

    Sondheimer Oscillation as a Fingerprint of Surface Dirac Fermions

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    Topological states of matter challenge the paradigm of symmetry breaking, characterized by gapless boundary modes and protected by the topological property of the ground state. Recently, angle-resolved photoemission spectroscopy (ARPES) has revealed that semiconductors of Bi2_{2}Se3_{3} and Bi2_{2}Te3_{3} belong to such a class of materials. Here, we present undisputable evidence for the existence of gapless surface Dirac fermions from transport in Bi2_{2}Te3_{3}. We observe Sondheimer oscillation in magnetoresistance (MR). This oscillation originates from the quantization of motion due to the confinement of electrons within the surface layer. Based on Sondheimer's transport theory, we determine the thickness of the surface state from the oscillation data. In addition, we uncover the topological nature of the surface state, fitting consistently both the non-oscillatory part of MR and the Hall resistance. The side-jump contribution turns out to dominate around 1 T in Hall resistance while the Berry-curvature effect dominates in 3 T \sim 4 T

    Tuberculous Pericarditis Presenting as Multiple Free Floating Masses in Pericardial Effusion

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    Pericarditis is a rare manifestation of tuberculosis (Tb) in children. A 14-yr-old Korean boy presented with cardiac tamponade during treatment of pulmonary tuberculosis. He developed worsening anemia and persistent fever in spite of anti-tuberculosis medications. Echocardiography found free floating multiple discoid masses in the pericardial effusion. The masses and exudates were removed by pericardiostomy. The masses were composed of pink, amorphous meshwork of threads admixed with degenerated red blood cells and leukocytes with numerous acid-fast bacilli, which were confirmed as Mycobacterium species by polymerase chain reaction. The persistent fever and anemia were controlled after pericardiostomy. This is the report of a unique manifestation of Tb pericarditis as free floating masses in the effusion with impending tamponade

    Zinc status and growth of Korean infants fed human milk, casein-based, or soy-based formula: three-year longitudinal study

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    To evaluate the effect of feeding methods on growth and zinc nutritional status of infants early in life, we monitored from birth to 36 months in 51 infants who were exclusively fed human milk (HM, n = 20), casein-based formula (CBF, n = 12), or soy-based formula (SBF, n = 19) during the first five months of life. Zinc status was assessed by analyzing serum zinc concentrations and zinc intakes. Zinc contents in HM and formulas were measured. Zinc intake was estimated by weighing infants before and after feeding in the HM group and by collecting formula-intake records in the CBF and SBF groups. After solid foods were introduced, all foods consumed were also included to estimate zinc intake. The growth of infants in all groups was similar to that established for normal Korean infants. Human milk zinc concentrations declined as lactation progressed. Zinc concentrations in all formulas tested in this study were higher than HM and were also higher than those claimed by the manufacturers. During the first twelve months, mean serum zinc concentrations of infants were similar in all groups, although infants in the HM group consistently had the lowest zinc intake among the groups, and the overall zinc intake in infants fed SBF was highest. This finding could be explained by the different zinc bioavailability of HM and formulas. In conclusion, infants fed HM, CBF or SBF has normal growth up to three years of age, although HM contained the lowest zinc concentration followed by CBF, then SBF

    Phase Contrast Microradiography of Mouse Lung Using Synchrotron X-ray: Correlation with Optical Microscopy

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    Purpose: The purpose of this study is to evaluate the feasibility of phase contrast X-ray microtomography and microradiography, using a polychromatic synchrotron X-ray, for analysis of the mouse lung microstructure. Materials and Methods: Normal mice were used for experiments. Some of the mouse lungs were prepared by the lung fixation-inflation method. The resulting sponge-like inflated lung samples were used for microtomography. The remaining mouse lungs were cut into 10 um sections and were used for microradiography and optical microscopic correlation. The experiments on mouse lung samples were per-formed at the 7B2 beamline of the Pohang Light Source in Korea. Results: Phase contrast X-ray microtomography of inflated lung samples showed individual alveolar structure on 3-D reconstruction. Phase contrast microradiographs of thin lung samples showed microstructure of lung, such as alveoli and bronchioles, and were well correlated with optical microscopic images. Conclusions: The results indicate that the phase contrast X-ray microtomography and microradiography using polychromatic synchrotron X-ray is feasible for evaluation of microstructure of the lung.X115sciescopuskc

    A case of granulomatous lung disease in a patient with Good's syndrome

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    Good's syndrome is extremely rare. This adult-onset condition is characterized by a thymoma with immunodeficiency, low B- and T-cell counts, and hypo-gammaglobulinemia. The initial clinical presentation is either a mass-lesion thymoma or a recurrent infection. Patients with Good's syndrome are very susceptible to infections; common respiratory and opportunistic infections can be life-threatening. There are no reports of granulomatous lung disease in patients with Good's syndrome, although it has been observed in patients with common variable immunodeficiency, of which Good's syndrome is a subset. We describe a 53-year-old male thymoma patient who presented with respiratory symptoms caused by granulomatous lung disease and an opportunistic infection. He died of uncontrolled fungal infection despite repeated intravenous immunoglobulin and supportive care. Clinicians should look for evidence of immunologic dysfunction in thymoma patients presenting with severe recurrent infections, especially opportunistic infections

    Korean Ginseng-Induced Occupational Asthma and Determination of IgE Binding Components

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    A number of case reports on occupational asthma caused by herbal medicines have been issued, for example, on Sanyak, Chunkung, Banha, and Brazilian ginseng. Recently, cases of occupational asthma induced by Sanyak and Korean ginseng have been reported, but the pathogenic mechanisms involved are unknown. This study was carried out to evaluate the immunologic mechanism underlying Korean ginseng-induced occupational asthma. A patient engaged in Korean ginseng wholesale was referred for recurrent dyspnea, wheezing, and nasal symptoms, which were aggravated at work. Allergen bronchial provocation testing to Korean ginseng extract showed a typical immediate response, and skin prick testing to Korean ginseng extract also showed a strong positive response. Moreover, serum-specific IgE levels to Korean ginseng extract were significantly higher than in controls. Enzyme-linked immunosorbent assay (ELISA) inhibition tests showed a dose-dependent inhibition by Korean ginseng, but not by Dermatophagoides farinae, wheat flour, or Chinese balloon flower. Sodium dodecylsulfate-poly-acrylamide gel electrophoresis (SDS-PAGE) and immunoblotting revealed four specific Immunoglobulin E (IgE) binding components at 26, 30, 47, and 60 kDa, which were not bound by control sera. These results strongly suggest that occupation asthma induced by Korean ginseng is induced via an IgE-mediated mechanism

    Nutritional Status of Vitamin D and the Effect of Vitamin D Supplementation in Korean Breast-fed Infants

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    We investigated the vitamin D status and the effect of vitamin D supplementation in Korean breast-fed infants. The healthy term newborns were divided into 3 groups; A, formula-fed; B, breast-fed only; S, breast-fed with vitamin D supplementation. We measured serum concentrations of vitamin D (25OHD3), calcium (Ca), phosphorus (P), alkaline phosphatase (AP), intact parathyroid hormone (iPTH) and bone mineral density (BMD) at 6 and 12 months of age. Using questionnaires, average duration of sun-light exposure and dietary intake of vitamin D, Ca and P were obtained. At 6 and 12 months of age, 25OHD3 was significantly higher in group S than in group B (P<0.001). iPTH was significantly lower in group S than in group B at 6 months (P=0.001), but did not differ at 12 months. Regardless of vitamin D supplementation, BMD was lower in group B and S than in group A (P<0.05). Total intake of vitamin D differed among 3 groups (P<0.001, A>S>B), but total intake of Ca and P were higher in group A than in group B and S (P<0.001). In conclusion, breast-fed infants show lower vitamin D status and bone mineralization than formula-fed infants. Vitamin D supplementation (200 IU/day) in breast-fed infants increases serum 25-OH vitamin D3, but not bone mineral density

    Rescue therapy with adefovir in decompensated liver cirrhosis patients with lamivudine-resistant hepatitis B virus

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    Background/AimsAdefovir dipivoxil (ADV) is a nucleotide analogue that is effective against lamivudine-resistant hepatitis B virus (HBV). The aim of this study was to determine the long-term clinical outcomes after ADV rescue therapy in decompensated patients infected with lamivudine-resistant HBV.MethodsIn total, 128 patients with a decompensated state and lamivudine-resistant HBV were treated with ADV at a dosage of 10 mg/day for a median of 33 months in this multicenter cohort study.ResultsFollowing ADV treatment, 86 (72.3%) of 119 patients experienced a decrease in Child-Pugh score of at least 2 points, and the overall end-stage liver disease score decreased from 16±5 to 14±10 (mean ± SD, P<0.001) during the follow-up period. With ADV treatment, 67 patients (56.3%) had undetectable serum HBV DNA (detection limit, 0.5 pg/mL). Virologic breakthrough occurred in 38 patients (36.1%) and 9 patients had a suboptimal ADV response. The overall survival rate was 89.9% (107/119), and a suboptimal response to ADV treatment was associated with both no improvement in Child-Pugh score (≥2 points; P=0.001) and high mortality following ADV rescue therapy (P=0.012).ConclusionsThree years of ADV treatment was effective and safe in decompensated patients with lamivudine-resistant HBV
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