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Biomedical subjects

K Shin

Publications and source records attributed to K Shin.

At least 19 recordsLinked to original sources
PubMed2006

Steroid myopathy in patients with acute graft-versus-host disease treated with high-dose steroid therapy.

High-dose steroids are the first line of treatment for acute graft-versus-host disease (aGVHD). Steroid myopathy is a debilitating steroid-induced complication that significantly impairs a patient's performance status. To determine the frequency and severity of steroid myopathy and other steroid related complications in patients with acute myeloid leukemia (AML)/myelodysplastic syndrome (MDS) who developed grade >or=2 aGVHD after allogeneic hematopoietic stem cell transplantation (HSCT), we performed a retrospective analysis. Patients were included in the analysis if they had a diagnosis of AML/MDS, underwent an allogeneic HSCT between January 1996 and December 2001 and developed grade >or=2 aGVHD that was treated with 2 mg/kg of methylprednisolone and survived at least 100 days post transplant. A total of 70 patients fulfilled our inclusion criteria. Steroid myopathy was identified in 29 (41%) patients. Steroid myopathy was generally of moderate severity with severe debilitating steroid myopathy seen in only 3% of patients. We concluded that steroid myopathy is a common complication of high-dose steroid therapy after allogeneic HSCT in AML/MDS. Interventions aimed at preventing and treating this complication are warranted and need to be explored in prospective clinical trials.

Acute Disease↗
PubMed2004

Expression of chemokine and inhibitory receptors on natural killer cells: effect of immune activation and HIV viremia.

We examined the cell-surface expression of chemokine and natural killer (NK) cell inhibitory receptors (iNKRs) on NK cells from individuals with human immunodeficiency virus (HIV) infection, chronic hepatitis C infection, and Wegener's granulomatosis (WG), an inflammatory, granulomatous vasculitis. The expression of CCR5 on NK cells was up-regulated in individuals with HIV viremia and in individuals with active WG, indicating that expression of this receptor is modulated by states of immune activation associated with viral infection and inflammatory or immune-mediated diseases. In contrast, iNKRs were shown to be up-regulated only on NK cells of individuals with HIV viremia, and they returned to a normal level when viremia was controlled with effective antiviral therapy. In individuals with HIV-1 viremia, there was a direct correlation between the level of expression of p58.1, p58.2, and CD94 receptors and plasma HIV viremia, suggesting that ongoing active HIV replication has an effect on the expression of such receptors on NK cells. These results suggest that immune activation leads to abnormal cell-surface expression of chemokine receptors on NK cells, whereas HIV-specific processes account for the up-regulation of iNKRs on NK cells; this may explain the NK cell-functional defects seen in HIV infection.

Antiretroviral Therapy, Highly Active↗
PubMed2003

X-ray scattering from freestanding polymer films with geometrically curved surfaces.

We show that the x-ray surface scattering from a freestanding polymer film exhibits features that cannot be explained by the usual stochastic formalism for surfaces with random height fluctuations. Instead, a geometric description of the film morphology assuming two curved surfaces characterized by a radius of curvature and a lateral cutoff length successfully accounts for the phase difference between the Kiessig fringes of the nominal "specular" and "off-specular" components of the scattering. The formalism allows one to distinguish unambiguously between conformal and anticonformal curvature morphologies at long length scales.

Journal Article↗
PubMed2002

Polyethylenimine-mediated cellular uptake, nucleus trafficking and expression of cytokine plasmid DNA.

Although polyethylenimine (PEI) has been widely used as a nonviral vector, there is little mechanistic understanding on PEI-mediated delivery. Here, we studied whether the expression of murine interleukin-2 (mIL-2) plasmids could be improved by complexation with PEI at various N/P ratios, and whether the cellular uptake, nuclear translocation, and retention of plasmids could be affected by the N/P ratios. Compared with the naked mIL-2, PEI/mIL-2 complexes showed at least two orders of magnitude higher expression at Raw264 cells in the N/P ratio-dependent manner. PEI-mediated cellular uptake and nuclear trafficking of plasmids, quantitated by competitive polymerase chain reaction, also depended on the N/P ratios showing the highest cell and nuclear levels of plasmids at 10/1. The higher cellular levels of plasmid DNA after PEI-mediated delivery were also observed in other cell lines. Unlike naked plasmids, PEI/mIL-2 complexes (N/P ratios >/=4/1) showed prolonged cellular and nuclear retention of mIL-2 plasmids. The nuclear translocation and higher cellular level of plasmids given in PEI complexes were similarly observed by fluorescence microscopy. Moreover, PEI/mIL-2 complexes revealed high stability against DNase I, partly explaining the prolonged subcellular retention. These results indicate that the expression of plasmid mIL-2 might be highly enhanced by complexation with PEI and that such increased expression could be attributed by the higher cellular uptake, nuclear translocation and prolonged retention.

Active Transport, Cell Nucleus↗
PubMed2002

Susceptibility of Helicobacter pylori and its urease activity to the peroxidase-hydrogen peroxide-thiocyanate antimicrobial system.

The susceptibility of Helicobacter pylori to the antimicrobial system involving lactoperoxidase, hydrogen peroxide and thiocyanate was investigated. The inhibitory effect of the system on the urease activity of H. pylori, which plays a role in its colonisation of the stomach, was also investigated. Twelve H. pylori strains examined, including 10 clinical isolates, were all inhibited by the peroxidase system in brain-heart infusion broth supplemented with fetal calf serum, but to different extents. The killing effect was observed within 3 h. Although bacterial viability recovered afterwards, there was still a clear difference between cultures incubated in the presence of the complete system and control cultures incubated in the absence of lactoperoxidase, after incubation for 24 h. The urease activity and viability of H. pylori were both inactivated by this system in phosphate buffer. These effects were dependent on the concentrations of both lactoperoxidase and hydrogen peroxide and were abolished by the addition of cysteine. Furthermore, these effects were observed when bovine lactoperoxidase was replaced by recombinant human lactoperoxidase or native or recombinant human myeloperoxidase. The peroxidase system found in saliva and milk may contribute to the host defence against H. pylori infection and inhibition of transmission via the oral route.

Animals↗
PubMed2001

Molecular cloning and functional expression of a human intestinal lactoferrin receptor.

Lactoferrin (Lf), a major iron-binding protein in human milk, has been suggested to have multiple biological roles such as facilitating iron absorption, modulating the immune system, embryonic development, and cell proliferation. Our previous binding studies suggested the presence of a specific receptor for Lf (LfR) in the small intestine of newborn infants, which may facilitate iron absorption. We here report the cloning and the functional expression of the human intestinal LfR and the evidence of its involvement in iron metabolism. The entire coding region of the LfR cDNA was cloned by PCR based on amino acid sequences of the purified native LfR (nLfR). The recombinant LfR (rLfR) was then expressed in a baculovirus-insect cell system and purified by immobilized human Lf (hLf) affinity chromatography where binding of hLf to the rLfR was partially Ca(2+) dependent. The apparent molecular mass was 136 kDa under nonreducing conditions and 34 kDa under reducing conditions. 125I-hLf bound to the rLfR with an apparent K(d) of approximately 360 nM. These biochemical properties of the rLfR are similar to those of the nLfR. RT-PCR revealed that the gene was expressed at high levels in fetal small intestine and in adult heart and at lower levels in Caco-2 cells. PI-PLC treatment of Caco-2 cells indicated that the LfR is GPI anchored. In Caco-2 cells transfected with the LfR gene, 125I-hLf binding and 59Fe-hLf uptake were increased by 1.7 and 3.4 times, respectively, compared to those in mock-transfected cells. Our findings demonstrate the presence of a unique receptor-mediated mechanism for nutrient uptake by the newborn.

Adult↗
PubMed2001

Mutations affecting the calcium-binding site of myeloperoxidase and lactoperoxidase.

Both myeloperoxidase (MPO) and lactoperoxidase (LPO) contain high affinity bound calcium, which has been suggested to play a structural role. Asp-96 in MPO, a residue next to the histidine distal from the heme prosthetic group, has been assigned to the calcium-binding site of the enzyme by X-ray crystallography. Multiple sequence alignment of known animal peroxidases has revealed that the calcium-binding site is highly conserved. In this study, we replaced Asp-96 in MPO and the counterpart Asp-227 in LPO both with Ala by site-directed mutagenesis. The level of peroxidase activity in insect cells infected with recombinant baculoviruses and their culture supernatants was reduced to virtually zero as a result of these mutations. Immunoblotting revealed that these mutant peroxidases were expressed in the cells but not secreted as effectively as the wild-type enzymes. Our findings suggest that a functional calcium-binding site is essential for the biosynthesis of active animal peroxidases.

Amino Acid Sequence↗
PubMed2001

Temporal non-linearities of the cochlear amplifier revealed by maximum length sequence stimulation.

OBJECTIVES: The objective of this study was to examine whether temporal non-linearities of the cochlear amplifier, as reflected by otoacoustic emissions (OAEs), exist and are distinct from any recording system non-linearities. METHODS: Maximum length sequence stimulation, at various stimulus rates, was used to evoke OAEs from normally hearing subjects. Recordings from a 2cc cavity were also made. The data were analyzed to obtain the linear response and estimates of the slices of the 2nd and 3rd order Volterra kernels. This provided a measure of two and 3 click non-linear temporal interactions, respectively. RESULTS: The results showed that temporal non-linearities of OAEs do exist, are stable and repeatable within individuals and have properties that differ from those shown by the conventional linear response. Whilst some of the non-linear response properties conformed to the expected pattern, of increasing amplitude with increase in stimulus rate, there are some areas in which they show an unpredicted complexity. CONCLUSIONS: Whilst system non-linearities could be found, there was no difficulty in distinguishing between the physiological and system non-linear components. New areas of research and application may result from the use of these new OAE responses.

Acoustic Stimulation↗
PubMed2001

Inhibition of Escherichia coli respiratory enzymes by the lactoperoxidase-hydrogen peroxide-thiocyanate antimicrobial system.

AIMS: The lactoperoxidase-hydrogen peroxide-thiocyanate antimicrobial system (LPAS) is known to inhibit bacterial respiration. In the present study, several respiratory enzymes of Escherichia coli were compared in terms of their susceptibility to the LPAS. METHODS AND RESULTS: Exposure of E. coli to the LPAS, upon which 99.6% of the bacteria were killed, resulted in the following percentage of inactivation of substrate-specific membrane oxidases: succinate (94.2%) > NADH (84.6%) > glycerol-3-phosphate (67.8%) > DL-lactate (64.1%). With the same treatment, substrate-specific membrane dehydrogenases were inactivated as follows: succinate (99.1%) > DL-lactate (53.8%) > glycerol-3-phosphate (45.0%) > NADH (36.8%). Terminal oxidase, however, measured using a ubiquinone analogue (2,3-dimethoxy-5-methyl-6-decyl-1,4-benzoquinone) after reduction, was only 21.4% inactivated by the LPAS. CONCLUSION: These data suggest that dehydrogenases are the primary targets of the LPAS in the respiratory chain of E. coli. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has determined for the first time the primary targets of LPAS in the bacterial respiratory chain.

Anti-Bacterial Agents↗
PubMed2001

Purification and quantification of lactoperoxidase in human milk with use of immunoadsorbents with antibodies against recombinant human lactoperoxidase.

BACKGROUND: Two heme-containing peroxidases, secretory lactoperoxidase and leukocyte-derived myeloperoxidase, which play host defense roles through antimicrobial activity, were previously identified in human colostrum. Within several days after the start of lactation, the relative contribution of myeloperoxidase to the peroxidase activity in milk was shown to decline as the number of milk leukocytes decreased. OBJECTIVE: Our knowledge of lactoperoxidase in human milk is still limited. The objective of this study was to use specific antibodies as a means of simplifying the purification and quantification of lactoperoxidase. DESIGN: Polyclonal antibodies were raised against recombinant human lactoperoxidase. Immunoglobulin G (IgG) was isolated by means of a protein A column and was characterized by immunoblotting. For the purification of lactoperoxidase from whey, a cation-exchange column and an immunoaffinity column with coupled IgG were used. The concentration of lactoperoxidase was determined by a sandwich enzyme-linked immunosorbent assay by using purified native lactoperoxidase as a standard. Native and biotinylated IgG were used as capture and detector antibodies, respectively. RESULTS: Two bands with molecular masses of approximately 80 and 100 kDa were detected in an immunoblot of human whey. Similar heterogeneity was observed in the sodium dodecyl sulfate-polyacrylamide gel electophoresis profile of purified lactoperoxidase. The mean (+/-SD) concentration of lactoperoxidase in 26 whey samples was estimated to be 0.77 +/- 0.38 mg/L. The concentrations were positively correlated with the peroxidase activity detected in these samples. CONCLUSION: Lactoperoxidase is commonly present in human milk throughout the lactation period and is likely to contribute to the protective effects of milk.

Antibodies↗
PubMed2001

Radioactivity induced in a 2.5 GeV electron beam dump.

The saturation activity of residual nuclei was estimated based on measurements when 2.5 GeV electron beams were totally absorbed in thick Al, Fe, Cu and Pb. A calculation was also made for a beam dump from 0.1 to 10 GeV using the EGS4 and PICA95 Monte Carlo codes. Above 1 GeV, the activity was constant in units of MBq.W-1. The gamma ray dose rates from the targets were calculated using these data.

Aluminum↗
PubMed2001

An experimental study on radiation streaming through a labyrinth in a proton accelerator facility of intermediate energy.

A radiation streaming experiment has been carried out at the Takasaki Ion Accelerator Facility for Advanced Radiation Application at the Japan Atomic Energy Research Institute in a room housing a Cu target irradiated with 68 MeV protons and in a labyrinth of three-legs having a total length of 29 m. In the experiment, neutron and gamma ray energy spectra, neutron reaction rates, and neutron and gamma ray dose equivalent rates were measured using various counters and dosimeters. The experimental data show the applicability of some empirical formulas for estimating the thermal neutron flux in a room and neutrons streaming in a labyrinth designed for a proton accelerator operating in the intermediate energy region. The data suggest that it is mandatory to estimate the gamma ray dose equivalent rate in a labyrinth, which is dominated by the secondary gamma rays due to the neutron capture reaction.

Academies and Institutes↗
PubMed2001

[Periodontal plastic surgery as a regenerative medical science].

A regenerative medical science is the medical field of the next generation for a human's tissue and organ reproducing original structure and an original function. On the other hand, periodontal plastic surgery (PPS) defines as surgical procedures performed to correct or eliminate deformities of the gingival or alveolar mucosa. Therefore, PPS is considered to be one field in a regenerative medical science. In addition to the free soft tissue graft from the former, a guided tissue regeneration (GTR) and/or enamel matrix derivative has come to be used. This paper displays and explains clinical cases about the PPS from the standpoint of a regenerative medical science.

English Abstract↗
PubMed2000

DNA electrophoresis on a flat surface.

We report a new approach for performing DNA electrophoresis. Using experimental studies and molecular dynamics simulations, we show that a perfectly flat silicon wafer, without any surface features, can be used to fractionate DNA in free solution. We determine that the ability of a flat surface to separate DNA molecules results from the local friction between the surface and the adsorbed DNA segments. We control this friction by coating the Si surface with silane monolayer films and show that it is possible to systematically change the size range of DNA that can be separated.

DNA↗
PubMed2000

cAMP response element-mediated gene transcription is upregulated by chronic antidepressant treatment.

Regulation of gene transcription via the cAMP-mediated second messenger pathway has been implicated in the actions of antidepressant drugs, but studies to date have not demonstrated such an effect in vivo. To directly study the regulation of cAMP response element (CRE)-mediated gene transcription by antidepressants, transgenic mice with a CRE-LacZ reporter gene construct were administered one of three different classes of antidepressants: a norepinephrine selective reuptake inhibitor (desipramine), a serotonin selective reuptake inhibitor (fluoxetine), or a monoamine oxidase inhibitor (tranylcypromine). Chronic, but not acute, administration of these antidepressants significantly increased CRE-mediated gene transcription, as well as the phosphorylation of CRE binding protein (CREB), in several limbic brain regions thought to mediate the action of antidepressants, including the cerebral cortex, hippocampus, amygdala, and hypothalamus. These results demonstrate that chronic antidepressant treatment induces CRE-mediated gene expression in a neuroanatomically differentiated pattern and further elucidate the molecular mechanisms underlying the actions of these widely used therapeutic agents.

Animals↗
PubMed2000

PCR cloning and baculovirus expression of human lactoperoxidase and myeloperoxidase.

Lactoperoxidase (LPO) and myeloperoxidase (MPO) have been identified previously in human milk. These peroxidases have antimicrobial activity and presumably contribute to the protective functions of milk. In this study, we amplified genes encoding LPO and MPO from human mammary gland cDNA by the polymerase chain reaction (PCR). These genes were expressed in a baculovirus-insect cell system. Peroxidase activity was observed in the culture supernatant of Tricoplusia ni cells infected with the recombinant viruses and the levels increased upon addition of delta-aminolevulinic acid. Purified recombinant human LPO and MPO, both with a molecular mass of about 80 kDa, showed properties similar to bovine LPO and human MPO, respectively, in terms of absorption spectrum, sensitivity to dapsone, specificity for chloride ions, and reactivity with anti-bovine LPO or anti-MPO antibodies. Our data suggest that this expression system is useful for studying the catalytic mechanism and biological significance of these human peroxidases.

Baculoviridae↗
PubMed2000

Identification of lactoperoxidase in mature human milk.

Myeloperoxidase (MPO) derived from milk leukocytes and lactoperoxidase (LPO) secreted from the mammary gland have been identified previously in human colostrum. These peroxidases are known to play host defensive roles through antimicrobial activity. The goals of this study were to measure the peroxidase activity in mature human milk and to characterize the enzyme responsible for the activity. As determined using 3,3',5,5'-tetramethylbenzidine as substrate, whey prepared from human milk samples obtained 1 and 5 months postpartum showed levels of peroxidase activity equivalent to 0.13 +/- 0.18 and 0.24 +/- 0.21 microg/mL bovine LPO (bLPO; n = 13), respectively. Whey from early milk was fractionated into two peaks of peroxidase activity by cation-exchange chromatography; the peroxidase in the first peak was sensitive to dapsone, which is an inhibitor of LPO, whereas the second peroxidase was not. Whey from mature milk showed only the first peak. Purified bLPO and MPO showed chromatographic behaviors that were similar to the first and second peaks, respectively. The dapsone-sensitive peroxidase from mature milk was further purified (952-fold from whey) by hydrophobic interaction chromatography. This preparation showed two bands with molecular masses of 80 and 90 kDa by polyacrylamide gel electrophoresis and immunoblotting using an antibody against bLPO. After deglycosylation, two distinct proteins with lower molecular weights were observed. Amino acid sequencing indicated that both of these proteins are LPO. These results provide evidence that LPO is present in mature human milk and that it is responsible for most of the peroxidase activity in mature milk.

Journal Article↗