Boyoung Lee
Adventist University of the Philippines, Secondary Education, Graduate Student
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Um den akustischen Nachteil (vor allem das charakteristische Hochfrequenzgeraeusch) zu minimieren und Diesel-Pkw fuer den Endverbraucher attraktiver zu gestalten, hat Hyundai neue Akustikpakete fuer verschiedene Bereiche des Fahrzeugs... more
Um den akustischen Nachteil (vor allem das charakteristische Hochfrequenzgeraeusch) zu minimieren und Diesel-Pkw fuer den Endverbraucher attraktiver zu gestalten, hat Hyundai neue Akustikpakete fuer verschiedene Bereiche des Fahrzeugs entwickelt. Diese umfassen unter anderem Technologien zur Motorkapselung und einen schallabsorbierenden Teppich fuer den Innenraum. Zunaechst wurden zur gezielten Auslegung die akustischen Schwachpunkte bisheriger Pakete mit Hilfe der reziproken Holografie des PBNR-Verfahrens (Power Based Noise Reduction) sichtbar gemacht. Dabei handelt es sich um ein experimentelles Verfahren zur Visualisierung des Geraeuschminderungspegels bei einer bestimmten Frequenz. Anschliessend wurden die Teile des Akustikpakets optimiert.
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Signaling via the p42/44 mitogen-activated protein kinase (MAPK) pathway has been shown to be a key intracellular signaling event that couples light to entrainment of the mammalian circadian clock located in the suprachiasmatic nucleus... more
Signaling via the p42/44 mitogen-activated protein kinase (MAPK) pathway has been shown to be a key intracellular signaling event that couples light to entrainment of the mammalian circadian clock located in the suprachiasmatic nucleus (SCN). Because many of the physiological effects of the MAPK pathway are mediated by extracellular signal-regulated kinase (ERK)-regulated kinases, it was of interest to identify kinase targets of ERK in the SCN. In this study, we examined whether mitogen- and stress-activated protein kinase 1 (MSK1) is a downstream target of ERK in the SCN and whether it couples to clock gene expression. Here we show that photic stimulation during the subjective night stimulates MSK1 phosphorylation at serine 360, an event required for robust kinase activation. Activated ERK and MSK1 were colocalized in SCN cell nuclei after photic stimulation. The in vivo administration of the MAP kinase kinase 1/2 inhibitor U0126 [1,4-diamino-2,3-dicyano-1,4-bis(o-aminophenylmercap...
Research Interests: Neuroscience, Biology, Cell Biology, Medicine, Cell line, and 15 moreHumans, Nitriles, Mice, Darkness, Circadian Rhythm, Animals, Light, The, Phosphorylation, Cell nucleus, Cell Cycle Proteins, Suprachiasmatic Nucleus, photic stimulation, Psychology and Cognitive Sciences, and Medical and Health Sciences
Excitotoxic cell death is one of the precipitating events in the development of temporal lobe epilepsy. Of particular prominence is the loss of GABAergic hilar neurons. Although the molecular mechanisms responsible for the selective... more
Excitotoxic cell death is one of the precipitating events in the development of temporal lobe epilepsy. Of particular prominence is the loss of GABAergic hilar neurons. Although the molecular mechanisms responsible for the selective vulnerability of these cells are not well understood, activation of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway has been implicated in neuroprotective responses to excitotoxicity in other neuronal populations. Here, we report that high levels of the striatal-enriched protein tyrosine phosphatase (STEP), a key regulator of ERK/MAPK signaling, are found in vulnerable somatostatin-immunoreactive hilar interneurons. Under both control conditions and after pilocarpine-induced status epilepticus (SE), ERK/MAPK activation was repressed in STEP-immunoreactive hilar neurons. This contrasts with robust SE-induced ERK/MAPK activation in the granule cell layer of the dentate gyrus, a cell region that does not express...
Research Interests: Neuroscience, Biology, Cell Biology, Apoptosis, Medicine, and 15 moreSomatostatin, Hippocampus, Mice, Animals, Male, Cell Death, Dentate Gyrus, Rats, Status Epilepticus, Protein Tyrosine Phosphatases, Interneurons, Protein Kinase Inhibitors, Psychology and Cognitive Sciences, Medical and Health Sciences, and Nerve degeneration
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Ferritic stainless steels have excellent stress corrosion resistance and a low coefficient of thermal expansion compared to austenitic stainless steels. Ferritic stainless steels of the 400 series have been available for automotive... more
Ferritic stainless steels have excellent stress corrosion resistance and a low coefficient of thermal expansion compared to austenitic stainless steels. Ferritic stainless steels of the 400 series have been available for automotive exhaust systems, heat exchangers, radiators etc. in various industries. Automotive exhaust manifolds especially require good heat resistance because the typical operation temperature(800°C) of the exhaust system is exposed to during engine operation. In this study, the effects of high temperature(800°C) characteristics on the mechanical and microstructure properties were investigated for lap joint of ferritic stainless steel(STS 429) mainly used as the automotive exhaust manifolds. The microstructure of lap joint was characterized by optical microscopy(OM), scanning electron microscopy(SEM) and X-ray diffraction(XRD). The mechanical property of lap joint was evaluated by tensile test. The tensile test results show that a significant decrease in ultimate t...
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Research Interests: Genetics, Biology, Cell Cycle, Cytotoxicity, Medicine, and 15 moreCats, Biological Sciences, Cell line, Humans, Genetic Enhancement, Animals, Gene transfer techniques, Vesicular Stomatitis Virus, Gene Delivery, Plasmid, Cell Survival, Feline immunodeficiency virus, Gene Transfer, GAG, and Viral Vector
To enhance the transduction efficiency (TE) of a recombinant adeno-associated virus 2 (rAAV2) in human cancer cells, we examined the combined effects of various chemicals known to influence the rAAV2 transduction process at distinct... more
To enhance the transduction efficiency (TE) of a recombinant adeno-associated virus 2 (rAAV2) in human cancer cells, we examined the combined effects of various chemicals known to influence the rAAV2 transduction process at distinct steps. Among the agents tested were trichostatin A, a histone deacetylase inhibitor, MG-132, a proteosome inhibitor, the genotoxic agents hydroxyurea, aphidicolin, etoposide and camptothecin, and tyrphostin-1, an epidermal growth factor receptor inhibitor. During or after chemical treatment, various human cancer cells were infected with rAAV2 expressing beta-galactosidase. Treatment with hydroxy-urea or etoposide plus tyrphostin-1 dramatically increased the TE in most cell lines. The combination of hydroxyurea plus tyrphostin-1 increased TE to 37.7+/-7.9%, 32.8+/-2.0% and 31.8+/-2.1% in SK-Hep1, HeLa, and HCT116 cells, respectively. In addition, following rAAV2 infection and treatment with hydroxyurea plus tyrphostin-1, long-term transgene expression was observed for up to 6 months, with no damage to the transduced cells. These results indicate that rAAV2 transgene expression can be significantly enhanced by a combination of chemical agents with distinct activity and prolonged gene expression can occur following rAAV2 gene transfer into human cancer cells.
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Research Interests: Cognitive Science, Biology, Cell Biology, Medicine, Signal Transduction, and 14 moreProtein Kinases, Mice, Circadian Rhythm, cyclic AMP, Animals, Cellular and Molecular Neuroscience, Protein Kinase, Circadian Clock, Suprachiasmatic Nucleus, Neurosciences, Catalytic Activity, Dark Adaptation, photic stimulation, and Signaling pathway
A major problem with reverse transcription-polymerase chain reaction (RT-PCR) is that the products amplified from RNA and DNA are not distinguishable. The use of a primer set targeted for an intron-containing sequence or RNA extract... more
A major problem with reverse transcription-polymerase chain reaction (RT-PCR) is that the products amplified from RNA and DNA are not distinguishable. The use of a primer set targeted for an intron-containing sequence or RNA extract without contaminating DNA has been established to overcome this problem. However, an intron sequence does not always exist in the target region and complete removal of DNA during RNA extraction is not practical. For these reasons, we developed differential amplifying RT-PCR (DART-PCR) based on differences in reaction temperatures between RT and PCR, as well as in architectures between RNA and DNA. DART-PCR was designed to differentiate products amplified from RNA and DNA regardless of the presence of introns. DART-PCR can be readily applied for diagnosis of active infection of human cytomegalovirus by detection of glycoprotein B mRNA, which gene lacks introns. Other advantages of DART-PCR were as follows: there is no need for separation of RNA from DNA, simultaneous/differential detection in a single tube and possibility of determination of relative amounts of RNA and DNA.
Research Interests: Microbiology, Molecular Biology, RNA, Medical Microbiology, Biology, and 15 moreMedicine, DNA, Cell line, Humans, Cytomegalovirus, Polymerase Chain Reaction, Gene, Introns, Intron, Differentiated Products, Reverse Transcriptase, Nucleic Acid Conformation, Human Cytomegalovirus, reverse transcriptase polymerase chain reaction, and Reverse transcription polymerase chain reaction
Signaling via the p42/p44 mitogen activated protein kinase (MAPK) pathway has been implicated as an intermediate event coupling light to entrainment of the mammalian circadian clock located in the suprachiasmatic nucleus (SCN). To examine... more
Signaling via the p42/p44 mitogen activated protein kinase (MAPK) pathway has been implicated as an intermediate event coupling light to entrainment of the mammalian circadian clock located in the suprachiasmatic nucleus (SCN). To examine how photic input dynamically regulates the activation state of the MAPK pathway, we monitored extracellular signal-regulated kinase (ERK) activation using different light stimulus paradigms. Compared with control animals not exposed to light, a 15 min light exposure during the early night triggered a marked increase in ERK activation and the translocation of ERK from the cytosol to the nucleus. ERK activation peaked 15 min after light onset, then returned to near basal levels within ∼45 min. The MAPK pathway could be reactivated multiple times by light pulses spaced 45 min apart, indicating that the MAPK cascade rapidly resets and resolves individual light pulses into discrete signaling events. Under conditions of constant light (120 min), the time...
Research Interests: Chemistry, Fluorescence Microscopy, Immunohistochemistry, Cell Biology, Confocal Microscopy, and 15 moreNeurophysiology, Medicine, Western blotting, Mice, Circadian Rhythm, Animals, Suprachiasmatic Nucleus, Protein Tyrosine Phosphatases, Extracellular, photic stimulation, Psychology and Cognitive Sciences, reverse transcriptase polymerase chain reaction, Mitogen- Activated Protein Kinases, Medical and Health Sciences, and Visual Pathways
Summary 1. Upon facing biotic stresses, plants orchestrate defence mechanisms via internal and external mechanisms that are mediated by signalling molecules such as salicylic acid, jasmonic acid, ethylene and various other volatile... more
Summary 1. Upon facing biotic stresses, plants orchestrate defence mechanisms via internal and external mechanisms that are mediated by signalling molecules such as salicylic acid, jasmonic acid, ethylene and various other volatile compounds. Although pathogen‐ and chemical‐induced plant resistance has been studied extensively within the same plant compartment, the effects of above‐ground (AG) insect‐elicited plant defence on the resistance expression in roots and the below‐ground (BG) microbial community are not well understood. 2. We assessed the effect of AG whitefly (Bemisia tabaci) attack on the elicitation of induced resistance against a leaf pathogen, Xanthomonas axonopodis pv. vesicatoria, a soil‐borne pathogen, Ralstonia solanacearum, and on BG modifications of the rhizosphere microflora in peppers (Capsicum annuum). 3. Symptom development caused by the two bacterial pathogens on leaves and roots was significantly reduced in whitefly‐exposed plants as compared to controls. ...
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The transcriptional feedback circuit, which is at the core of the suprachiasmatic nucleus (SCN) circadian (i.e., 24 h) clock, is tightly coupled to both external entrainment cues, such as light, as well as rhythmic cues that arise on a... more
The transcriptional feedback circuit, which is at the core of the suprachiasmatic nucleus (SCN) circadian (i.e., 24 h) clock, is tightly coupled to both external entrainment cues, such as light, as well as rhythmic cues that arise on a system-wide level within the SCN. One potential signaling pathway by which these cues are conveyed to the molecular clock is the CREB/CRE transcriptional cascade. In this study, we employed a tetracycline-inducible CREB repressor mouse strain, in which approximately 60% of the SCN neurons express the transgene, to test CREB functionality in the clock and its effects on overt rhythmicity. We show that attenuated CREB signaling in the SCN led to a significant reduction in light-evoked clock entrainment. An examination of circadian timing revealed that CREB repressor mice exhibited normal free-running rhythms in the absence of external lighting cues. However, under conditions of constant light, which typically leads to a lengthening of the circadian peri...
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Research Interests: Cancer, Biology, Cytotoxicity, Cancer Research, Apoptosis, and 15 moreMedicine, Cell Culture, Cell line, Humans, Cancer Therapy, Gastric Cancer, Polymerase Chain Reaction, Cancer Cell, Camptothecin, Protein Binding, Adenocarcinoma, binding sites, Stomach neoplasms, advanced gastric cancer, and cytolysis
The Ihh (Indian Hedgehog) pathway plays an essential role in facilitating chondrocyte hypertrophy and bone formation during skeletal development. Nkx3.2 (NK3 homeobox 2) is initially induced in chondrocyte precursor cells, maintained in... more
The Ihh (Indian Hedgehog) pathway plays an essential role in facilitating chondrocyte hypertrophy and bone formation during skeletal development. Nkx3.2 (NK3 homeobox 2) is initially induced in chondrocyte precursor cells, maintained in early-stage chondrocytes and down-regulated in terminal-stage chondrocytes. Consistent with these expression patterns, Nkx3.2 has been shown to enhance chondrocyte differentiation and cell survival, while inhibiting chondrocyte hypertrophy and apoptosis. Thus, in the present study, we investigated whether Nkx3.2, an early-stage chondrogenic factor, can be regulated by Ihh, a key regulator for chondrocyte hypertrophy. We show that Ihh signalling can induce proteasomal degradation of Nkx3.2. In addition, we found that Ihh can suppress levels of Lrp (low-density-lipoprotein-receptor-related protein) (Wnt co-receptor) and Sfrp (secreted frizzled-related protein) (Wnt antagonist) expression, which, in turn, may selectively enhance Lrp-independent non-cano...
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Research Interests: Biology, Cell Biology, Signal Transduction, Biological Sciences, Clinical Sciences, and 7 moreKinase, Biochemistry and cell biology, Vascular Endothelial Growth Factor, Psychology and Cognitive Sciences, Medical and Health Sciences, Cardiovascular medicine and haematology, and Medical biochemistry and metabolomics
Formation of reactive oxygen and nitrogen species is a precipitating event in an array of neuropathological conditions. In response to excessive reactive oxygen species (ROS) levels, transcriptionally dependent mechanisms drive the... more
Formation of reactive oxygen and nitrogen species is a precipitating event in an array of neuropathological conditions. In response to excessive reactive oxygen species (ROS) levels, transcriptionally dependent mechanisms drive the up‐regulation of ROS scavenging proteins which, in turn, limit the extent of brain damage. Here, we employed a transgenic approach in which cAMP‐response element binding protein (CREB)‐mediated transcription is repressed (via A‐CREB) to examine the contribution of the CREB/cAMP response element pathway to neuroprotection and its potential role in limiting ROS toxicity. Using the pilocarpine‐evoked repetitive seizure model, we detected a marked enhancement of cell death in A‐CREB transgenic mice. Paralleling this, there was a dramatic increase in tyrosine nitration (a marker of reactive species formation) in A‐CREB transgenic mice. In addition, inducible expression of peroxisome proliferator‐activated receptor gamma coactivator‐1α was diminished in A‐CREB ...