Hallym University

About: Hallym University is a education organization based out in Chuncheon, South Korea. It is known for research contribution in the topics: Population & Medicine. The organization has 10605 authors who have published 18891 publications receiving 302498 citations.

Astroglial loss and edema formation in the rat piriform cortex and hippocampus following pilocarpine-induced status epilepticus.

Abstract: In the present study we analyzed aquaporin-4 (AQP4) immunoreactivity in the piriform cortex (PC) and the hippocampus of pilocarpine-induced rat epilepsy model to elucidate the roles of AQP4 in brain edema following status epilepticus (SE). In non-SE-induced animals, AQP4 immunoreactivity was diffusely detected in the PC and the hippocampus. AQP4 immunoreactivity was mainly observed in the endfeet of astrocytes. Following SE the AQP4-deleted area was clearly detected in the PC, not in the hippocampus. Decreases in dystrophin and α-syntrophin immunoreactivities were followed by reduction in AQP4 immunoreactivity. These alterations were accompanied by the development of vasogenic edema and the astroglial loss in the PC. In addition, acetazolamide (an AQP4 inhibitor) treatment exacerbated vasogenic edema and astroglial loss both in the PC and in the hippocampus. These findings suggest that SE may induce impairments of astroglial AQP4 functions via disruption of the dystrophin/α-syntrophin complex that worsen vasogenic edema. Subsequently, vasogenic edema results in extensive astroglial loss that may aggravate vasogenic edema.

Light Element Analysis of Individual Microparticles Using Thin-Window EPMA

Abstract: The determination of the concentration of light elements, such as carbon, nitrogen and oxygen, in e.g. atmospheric aerosol particles is important to study the chemical behaviour of atmospheric pollution. The knowledge of low-Z element concentrations gives us information on the speciation of nutrients (species having nutritional value for plants) and toxic heavy metals in the particles. The capability of the conventional energy-dispersive EPMA is strongly limited for the analysis of low-Z elements, mainly because the Be window in the EDX detector hinders the detection of characteristic X-rays of light elements such as C, N, O and Na. WDS is suitable for analysis of light elements, but the measurement of beam sensitive microparticles requires the minimisation of the beam current and the measurement time. A semi-quantitative analytical method based on EPMA using an ultra-thin window EDX detector was developed. It was found that the matrix and geometric effects that are important for low-energy X-rays can be reliably evaluated by Monte Carlo calculations. Therefore, the quantification part of the method contains reverse Monte Carlo calculation done by iterative simulations. The method was standardised and tested by measurements on single particles with known chemical compositions. Beam-sensitive particles such as ammonium-sulphate and ammonium-nitrate were analysed using a liquid nitrogen cooled sample stage. The shape and size of the particles, which are important for the simulations, were determined using a high-magnification secondary electron image. Individual marine aerosol particles collected over the North Sea by a nine-stage Berner cascade impactor were analysed using this new method. Preliminary results on five samples and 4500 particles show that the method can be used to study the modification of sea-salt particles in the troposphere.

High glucose increases extracellular matrix production in pancreatic stellate cells by activating the renin-angiotensin system.

Abstract: Pancreatic stellate cells (PSCs) are involved in pancreatic inflammation and fibrosis. Recent studies have shown that blocking the renin-angiotensin system (RAS) attenuates pancreatic inflammation and fibrosis. However, there are few data about the direct effects of high glucose on extracellular matrix (ECM) protein synthesis and angiotensin II (Ang II) induction in PSCs. PSCs were isolated from male Sprague-Dawley rats and cultured in medium containing 5.5 mM (LG group) or 27 mM D-glucose (HG group). Levels of Ang II and transforming growth factor-beta (TGF-beta) in culture media were measured and Ang II-positive cells were counted. We used real-time polymerase chain reaction (PCR) to detect Ang II receptor expression and Western blot analysis for the expression of ECM proteins such as connective-tissue growth factor (CTGF) and collagen type IV. Cells were also treated with an Ang II-receptor antagonist (candesartan, 10 microM) or angiotensin-converting enzyme (ACE) inhibitor (ramiprilat, 100 nM). Thymidine uptake by PSCs increased fourfold with high glucose treatment. Ang II levels and the proportion of Ang II-positive PSCs were significantly increased after 6 h under high-glucose conditions. TGF-beta concentrations also increased significantly with high glucose. After 72 h, the expression of CTGF and collagen type IV proteins in high-glucose cultures increased significantly and this increase was effectively attenuated by the candesartan or the ramiprilat. All together, high glucose induced PSCs proliferation and ECM protein synthesis, and these effects were attenuated by an Ang II-receptor antagonist. The data suggest that pancreatic inflammation and fibrosis aggravated by hyperglycemia, and Ang II play an important role in this pathogenesis.

Gastrodin decreases immunoreactivities of gamma-aminobutyric acid shunt enzymes in the hippocampus of seizure-sensitive gerbils.

Abstract: Gastrodin is one of the natural compound isolated from Gastrodia elata and has known anticonvulsant effects, although the exact pharmacological principles of this natural compound and its effects on other aspects of gamma-aminobutyric acid (GABA) metabolism in vivo have not been explored. Therefore, in the present study, the effects of gastrodin on GABA metabolism in the gerbil hippocampus were examined, in an effort to identify the antiepileptic characteristics of this substance. Gastrodin reduced the seizure score in the treated group, although the immunoreactivities of GABA synthetic enzymes and GABA transporters were unaltered in gastrodin-treated animals. Interestingly, in the gastrodin-treated group, GABA transaminase (GABA-T) immunoreactivity in the hippocampus, particularly in neurons, was significantly decreased. In the gastrodin-treated group, both succinic semialdehyde dehydrogenase (SSADH) and succinic semialdehyde reductase (SSAR) immunoreactivities in the hippocampus was also decreased significantly, which stood in contrast to the nontreated group, in which strong SSADH and SSAR immunoreactivities were detected. From the neuroanatomical viewpoint, these findings suggest that gastrodin may cause the elevation of GABA concentration by inhibiting the GABA shunt.