Dominance specific visual extinction associated with callosal disconnection

Callosal disconnection signs are closely related to asymmetric hemispheric specialization of cognitive functions. Although extinction is more commonly associated with the right parietotemporal lesion, it may occur following lesions of the corpus callosum. After an infarction involving the left splenium, a 58-year-old right-handed man had no disconnection symptoms that had been reported earlier, but showed visual extinction with left or right visual hemifield dominant stimuli. Our results suggest that dominance specific visual extinction might be another disconnection sign associated with splenial lesion.

Synthesis and properties of a polyhedral oligomeric silsesquioxane-based new light-emitting nanoparticle

A polyhedral oligomeric silsesquioxane (POSS)-based electroluminescent nanoparticle, POSS-NPA, which contains anthracenenaphthyl chromophores on each of its eight arms, was easily prepared via the hydrosilylation reaction between octakis(dimethylsiloxy)silsesquioxane and allyl-functionalized 9-naphthalene-2-yl-10-phenyl anthracene chromophores. POSS-NPA was completely soluble in common organic solvents such as chloroform, THF, toluene, p-xylene, and chlorobenzene, and showed good film-forming properties on a quartz plate or an indium tin oxide (ITO) plate, i.e., it has good solution processing properties. The UV-visible absorption and the photoluminescence (PL) emission maxima of POSS-NPA in chlorobenzene solution were found to be 378 nm and 433 nm while those of POSS-NPA in the solid state were 379 and 464 nm, respectively. An electroluminescent (EL) device with the configuration of ITO/PEDOT:PSS/POSS-NPA (50 nm)/BAIq (40 nm)/LiF (1 nm)/Al (120 nm) was also fabricated and the blue light emission was successfully obtained.

Bacterial adhesion, cell adhesion and biocompatibility of Nafion films

We investigated bioadhesion (bacterial and cell adhesion) and biocompatibility of poly(tetrafluoroethylene-co-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid) (Nafion) and compared the results with those obtained with poly(vinylidene fluoride-co-hexafluoropropylene) (PVFHFP). When incubated with bacteria for 4 h to 7 days, Nafion film exhibited scarce bacterial adhesion at 6 h, after which the adhesion gradually increasing to relatively low levels. In contrast, significant bacterial adhesion to PVFHFP film was observed at 4 h, and much higher adhesion levels were shown thereafter. Although HEp-2 human cells adhered normally to both films, reaching confluence in 7-8 days, the cells adhered to Nafion appeared more lively and stable than those to PVFHFP. Subcutaneous implantation in mice revealed that Nafion elicited a mild acute inflammatory reaction without chronic inflammation or tissue necrosis, indicating excellent biocompatibility in mice. PVFHFP, however, provoked a moderate and prolonged acute inflammatory response. These differences in the biological characteristics of Nafion and PVFHFP films may be attributable to the differences in the chemical and physical natures of these polymer films. Nafion film provided a sufficiently solid support, expressing a high surface charge density and good water-wettability. In summary, Nafion is suitable for use in biomedical applications that require biocompatibility with a reduced possibility of post-operative infections.

Celecoxib induces hepatic stellate cell apoptosis through inhibition of Akt activation and suppresses hepatic fibrosis in rats

BACKGROUND AND AIMS

Activated hepatic stellate cells (HSCs) but not quiescent HSCs express cyclo-oxygenase-2 (COX-2), suggesting that the COX-2/prostanoid pathway has an active role in hepatic fibrogenesis. However, the role of COX-2 inhibitors in hepatic fibrogenesis remains controversial. The aim of this study was to investigate the antifibrotic effects of celecoxib, a selective COX-2 inhibitor.

METHODS

The effects of various COX inhibitors-that is, ibuprofen, celecoxib, NS-398 and DFU, were investigated in activated human HSCs. Then, the antifibrotic effect of celecoxib was evaluated in hepatic fibrosis developed by bile duct ligation (BDL) or peritoneal thioacetamide (TAA) injection in rats.

RESULTS

Celecoxib, NS-398 and DFU inhibited platelet-derived growth facor (PDGF)-induced HSC proliferation; however, only celecoxib (> or =50 microM) induced HSC apoptosis. All COX inhibitors completely inhibited prostaglandin E(2) (PGE(2)) and PGI(2) production in HSCs. Separately, PGE(2) and PGI(2) induced cell proliferation and extracellular signal-regulated kinase (ERK) activation in HSCs. All COX inhibitors attenuated ERK activation, but only celecoxib significantly inhibited Akt activation in HSCs. Celecoxib-induced apoptosis was significantly attenuated in HSCs infected with adenovirus containing a constitutive active form of Akt (Ad5myrAkt). Celecoxib had no significant effect on PPARgamma (peroxisome proliferator-activated receptor gamma) expression in HSCs. Celecoxib inhibited type I collagen mRNA and protein production in HSCs. Oral administration of celecoxib (20 mg/kg/day) significantly decreased hepatic collagen deposition and alpha-SMA (alpha-smooth muscle actin) expression in BDL- and TAA-treated rats. Celecoxib treatment significantly decreased mRNA expression of COX-2, alpha-SMA, transforming growth factor beta1 (TGFbeta1) and collagen alpha1(I) in both models.

CONCLUSIONS

Celecoxib shows a proapoptotic effect on HSCs through Akt inactivation and shows antifibrogenic effects in BDL- and TAA-treated rats, suggesting celecoxib as a novel antifibrotic agent of hepatic fibrosis.

Triplet harvesting for efficient white organic light emitting diodes

A novel hybrid device structure for efficient white organic light emitting diodes has been developed, which has a high hole injection barrier between a fluorescence blue emission layer and a electron transporting layer, and therefore excitons could be confined in the emission layer close to the electron transporting layer. A phosphorescent red dopant has been introduced into the electron transporting layer to harvest triplet states of the fluorescent blue emission layer and we have succeeded in obtaining the balanced white emission from blue singlet excitons and red triplet excitons with high efficiency. The optimized device showed the maximum external quantum efficiency of about 25% at 100 cd/m2.

Improvements of phosphorescent white OLEDs performance for lighting application

We developed white OLED device with high power efficiency, in which blue and orange phosphorescent emitters were used. By introduction of multi-functional interlayer which has partial doping of orange dopant inside EBL, we report WOLEDs with peak external efficiencies up to (14.1% EQE, 31.3 Im/W) without light out-coupling technique. At 1000 cd/m2, the performance achieved was 11.9% EQE, 18.7 Im/W with CIE = (0.39, 0.44). We also found that WOLED performances are related with doping ratio of the orange dopant that was inserted inside EBL.

Organic thin film transistor using a photo-curable organic/inorganic hybrid material as a gate dielectric

A polyhedral oligomeric silsesquioxane derivative (POSS-OXT) containing photo-curable 4-membered cyclic oxetane functional groups was used as a gate dielectric of organic field effect transistor. The POSS-OXT was cross-linked and completely solidified by UV irradiation in the presence of a selected photo acid generator, and pinhole free uniform thin film was obtained. We fabricated a metal/insulator/metal device of Au/POSS-OXT (300 nm)/Au with area of 0.7 mm2 and the measured leakage current and capacitance of the device to evaluate the insulating properties of the POSS-OXT thin film. The maximum current was about 0.25 nA when 40 V was applied to the device. The observed values of the capacitance per unit area and dissipation factor were 11.4 nF/cm2 and 0.025, respectively. We fabricated an organic thin film transistor with pentacene as the active semiconductor and the photo-cross-linked POSS-OXT as an insulator. A field effect carrier mobility of 0.03 cm2/VN s was obtained with the device.

Expression and serological application of a capsid protein of an iridovirus isolated from rock bream, Oplegnathus fasciatus (Temminck & Schlegel)

Iridoviruses infect a wide variety of wild and cultured fish. Those iridoviruses belonging to the genus Ranavirus, in the Iridoviridae family, cause systemic disease in infected animals with a high morbidity and mortality. This paper reports the cloning, sequencing, and expression of the rock bream iridovirus (RBIV) major capsid protein (MCP) in an Escherichia coli expression system for subsequent immunological studies. The completeness of the expressed protein was confirmed by peptide mass fingerprinting (PMF) analysis using MALDI-TOF MS. The recombinant MCP (rMCP)-specific mouse polyclonal antibody reacted with the viral 52 kDa protein, indicating that this rMCP induces an immunological response. Fish antibodies induced against iridovirus infection were also detected using ELISA when rMCP was used as an antigen. As a result, it was found that many cultured rock bream (92.5%) were naturally infected with iridovirus and that the rMCP might be useful for serological tests.

Limits on interactions between weakly interacting massive particles and nucleons obtained with CsI(Tl) crystal detectors

The Korea Invisible Mass Search (KIMS) experiment presents new limits on the weakly interacting massive particle (WIMP)-nucleon cross section using data from an exposure of 3409 kg.d taken with low-background CsI(Tl) crystals at the Yangyang Underground Laboratory. The most stringent limit on the spin-dependent interaction for a pure proton case is obtained. The DAMA signal region for both spin-independent and spin-dependent interactions for the WIMP masses greater than 20 GeV/c2 is excluded by the single experiment with crystal scintillators.

A biocompatibility study of a reinforced acrylic-based hybrid denture composite resin with polyhedraloligosilsesquioxane

Acrylic-based denture materials have several common weak points, such as shrinkage after curing, lack of strength and toxicity. In order to solve these problems, we adapted a hybrid system using acrylic polymer and polyhedraloligosilsesquioxane (POSS). The aim of the study was to investigate the biocompatibility of a reinforced acrylic-based hybrid denture composite resin with POSS. Specimens of a novel polymeric denture base resin, in which POSS was used to partially replace the commonly used base monomer, were fabricated. In order to examine changes in biocompatibility with time, fresh specimens, along with specimens soaked in distilled water for 24 and 72 h were fabricated. Three other types of acrylic denture base resins were used to prepare the resin specimens. Biocompatibility (as measured by a metabolic assay, an agar overlay test, and a mutagenesis assay) of the composites was tested. The metabolic and mutagenesis assays were conducted with pure culture medium as a control. In this study, the reinforced acrylic-based hybrid denture composite resin with POSS showed improved biocompatibility and lower mutagenicity than the control. Statistical examinations showed the cell metabolic activity of the novel polymeric denture base resin in the 72-h immersion case as having almost the same inclination as the control. We hope that these results might aid in the development of a reinforced acrylic-based denture resin.

Internal Pallidal Neuronal Activity During Mild Drug-Related Dyskinesias in Parkinson's Disease: Decreased Firing Rates and Altered Firing Patterns

The neuronal basis of hyperkinetic movement disorders has long been unclear. We now test the hypothesis that changes in the firing pattern of neurons in the globus pallidus internus (GPi) are related to dyskinesias induced by low doses of apomorphine in patients with advanced Parkinson's disease (PD). During pallidotomy for advanced PD, the activity of single neurons was studied both before and after administration of apomorphine at doses just adequate to induce dyskinesias (21 neurons, 17 patients). After the apomorphine injection, these spike trains demonstrated an initial fall in firing from baseline. In nine neurons, the onset of on was simultaneous with that of dyskinesias. In these spike trains, the initial fall in firing rate preceded and was larger than the fall at the onset of on with dyskinesias. Among the three neurons in which the onset of on occurred before that of dyskinesias, the firing rate did not change at the time of onset of dyskinesias. After injection of apomorphine, dyskinesias during on with dyskinesias often fluctuated between transient periods with dyskinesias and those without. Average firing rates were not different between these two types of transient periods. Transient periods with dyskinesias were characterized by interspike interval (ISI) independence, stationary spike trains, and higher variability of ISIs. A small but significant group of neurons demonstrated recurring ISI patterns during transient periods of on with dyskinesias. These results suggest that mild dyskinesias resulting from low doses of apomorphine are related to both low GPi neuronal firing rates and altered firing patterns.

Development of LiF:Mg,Cu,Si TL material (new KLT-300) with a low-residual signal and high-thermal stability

LiF-based thermoluminescence (TL) materials have been widely used for radiation dosimetry due to their attractive features. LiF:Mg,Cu,P is one of the most sensitive tissue-equivalent TL materials, approximately 40 times more sensitive than LiF:Mg,Ti (TLD-100), but it has two main drawbacks: a thermal loss of the TL sensitivity when annealed at temperatures>240 degrees C, and a relatively high-residual signal. Recently, LiF:Mg,Cu,Na,Si TL material was developed to overcome these drawbacks at the Korea Atomic Energy Research Institute, but it provided only marginal improvements in reducing the residual signal. The newly developed LiF:Mg,Cu,Si TL material has a significantly lower residual signal and a better stability to thermal treatments. In this article, the preparation method and some dosimetric properties (sensitivity and residual signal) of the new LiF:Mg,Cu,Si TL material are presented. At the end of the preparation procedures, a dual-step annealing method is introduced and this has proved as a very efficient method to reduce the high-temperature peak and is the cause of residual signal. Therefore, the high-temperature peak in the glow curve was significantly reduced. The sensitivity is approximately 20 times higher than that of TLD-100 and the residual signal was estimated to be approximately 0.04%.

Frequency and distribution of patellar luxation in dogs. 134 cases (2000 to 2005)

This study investigated the frequency and distribution of patellar luxation in the dogs presented to the Chonbuk National University Animal Medical Centre during January 2000 to September 2005. Patellar luxations were classified as medial or lateral, and unilateral or bilateral, were graded I to IV, and were subdivided according to age, sex and size of the dogs. The incidence of medial patellar luxation (MPL) was greater than the incidence of lateral patellar luxation (LPL) in both small and large dogs. Small-breed dogs were admitted almost exclusively with MPL. LPL was found uncommon; however it was observed more often in larger-breed dogs. Surgical correction was performed primarily in the dogs (165 stifles in 111 dogs) with grade II, III and IV patellar luxations following different surgical techniques. The combination of the surgical techniques was found to be more effective for the management of the disease. The prognosis was found to be favourable, because when the grade was low, the dog was younger, without cruciate ligament rupture, and as the surgical correction was performed with combination of more techniques.

Mitochondrial dysfunction induces aberrant insulin signalling and glucose utilisation in murine C2C12 myotube cells

AIMS/HYPOTHESIS

Mitochondrial dysfunction is considered a critical component in the development of diabetes. The aim of this study was to elucidate the molecular mechanisms involved in the development of insulin resistance and diabetes through investigation of mitochondrial retrograde signalling.

MATERIALS AND METHODS

Mitochondrial function of C2C12 myotube cells was impaired by genetic (ethidium bromide) and metabolic (oligomycin) stress, and changes in target molecules related to insulin signalling were analysed.

RESULTS

Concomitant with reductions in mitochondrial membrane potential (DeltaPsim) and ATP synthesis, production of IRS1 and solute carrier family 2 (facilitated glucose transporter), member 4 (SLC2A4, formerly known as GLUT4) were reduced. Moreover, serine phosphorylation of IRS1 increased, resulting in decreased tyrosine phosphorylation. This indicates that mitochondrial dysfunction decreases insulin-stimulated SLC2A4 translocation and glucose uptake. Mitochondrial stress activated c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK) signalling in a Ca(2+)-dependent manner, and removal of free Ca(2+) by BAPTA-AM, as well as inhibition of JNK and p38 MAPK, abrogated mitochondrial stress-induced reductions in IRS1 and SLC2A4 production. Mitochondrial dysfunction after oligomycin treatment significantly increased levels of activating transcription factor 3 (ATF3), which represses Irs1 promoter activity. Removal of the 5' flanking region of Irs1 demonstrated that the promoter region within 191 bases from the transcription site may be involved in the transcriptional repression of Irs1 by mitochondrial stress.

CONCLUSIONS/INTERPRETATION

We show distinct mitochondrial retrograde signalling, where Irs1 is downregulated through ATF3 in a Ca(2+)-, JNK- and p38 MAPK-dependent manner, and IRS1 is inactivated. Therefore, mitochondrial dysfunction causes aberrant insulin signalling and abnormal utilisation of glucose, as observed in many insulin resistance states.