Seung-Taeck Park

Nitric oxide production by high molecular weight water-soluble chitosan via nuclear factor-κB activation

Abstract High molecular weight water-soluble chitosan (WSC), having an average molecular weight of 300u2008000 Da and a degree of deacethylation over 90%, can be produced using a simple multi-step membrane separation process. In this study, the effect of WSC on the production of nitric oxide (NO) in RAW 264.7 macrophages was evaluated. Water-insoluble chitosan alone has been previously shown to exhibit in vitro stimulatory effect on macrophages NO production. However, WSC had no effect on NO production by itself. When WSC was used in combination with recombinant interferon-γ (rIFN-γ), there was a marked cooperative induction of NO synthesis in a dose-dependent manner. The optimal effect of WSC on NO synthesis was shown 24 h after treatment with rIFN-γ. The increased production of NO from rIFN-γ plus WSC-stimulated RAW 264.7 macrophages was decreased by the treatment with N G -monomethyl- l -arginine ( N G MMA). The increase in NO synthesis was reflected, as an increased amounts of inducible NO synthase protein. In addition, synergy between rIFN-γ and WSC was mainly dependent on WSC-induced tumor necrosis factor-α (TNF-α) and nuclear factor-κB (NF-κB) activation. The present results indicate that the capacity of WSC to increase NO production from rIFN-γ-primed RAW 264.7 macrophages is the result of WSC-induced TNF-α secretion via the signal transduction pathway of NF-κB activation.

Tongkyutang inhibits mast cell-dependent allergic reactions and inflammatory cytokines secretion

BACKGROUNDnTongkyutang (TKT) is an Oriental herbal prescription, which has been successfully applied for the treatment of allergic disorders, mainly allergic-rhinitis in clinical medicine. However, its effect in experimental models remains unknown.nnnMETHODSnIn a mouse model, the role of TKT was examined in mast cell-dependent allergic reactions and secretion of inflammatory cytokines.nnnRESULTSnTKT concentration-dependently inhibited the ear-swelling response induced by intradermal injection of compound 48/80. TKT inhibited the compound 48/80-induced degranulation from mast cells in ear tissue. TKT dose-dependently inhibited the histamine release from the rat peritoneal mast cells by compound 48/80. TKT also showed inhibition of anti-dinitrophenyl IgE antibody-induced passive cutaneous anaphylaxis reaction by oral administration. Furthermore, TKT inhibited both IL-1beta and TNF-alpha secretion induced by PMA and A23187, respectively.nnnCONCLUSIONSnOur findings provide evidence that TKT inhibits the mast cell-dependent allergic reactions and inflammatory cytokines secretion.

Polymorphism of the angiotensin-converting enzyme gene in patients with cerebral infarction in koreans

The relationship between cerebrovascular disease and an insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene is still being debated. The frequency of the DD genotype of the ACE gene was significantly higher in subjects with than those without cerebral infarction in Japan. The aim of the present study was to assess the relationship between ACE gene polymorphism and the development of cerebral infarction in a population from Korea. We examined its possible role as a risk factor in patients with cerebral infarction. The association between ACE gene polymorphism and cerebral infarction was examined in 106 patients with cerebral infarction and 498 controls without cerebral infarction. Frequencies of the genotypes and alleles of the ACE gene were investigated. The ACE genotype was analyzed by the polymerase chain reaction (PCR). The frequency of D allele was 37.7% in patients and 39.1% in controls (X2=0.128, p=0.720). The frequencies of the genotypes of the ACE gene were II:39.6%, ID:45.3%, and DD:15.1% in patients, and II:37.1%, ID:47.6%, and DD:15.3% in controls (X2=0.127, p=0.721). There was no significant difference in the frequency of the DD genotype of the ACE gene, and we did not find any association between ACE polymorphism and cerebral infarction. These results indicate that ACE polymorphism is not a risk factor for the development of cerebral infarction in a Korean population.

Nitric oxide and tumor necrosis factor-α production by Ixeris dentata in mouse peritoneal macrophages

Abstract Using mouse peritoneal macrophages, we have examined the mechanism by which Ixeris dentata (IXD) regulates nitric oxide (NO) production. When IXD was used in combination with recombinant interferon-γ (rIFN-γ), there was a marked cooperative induction of NO production. However, IXD had no effect on NO production by itself. The increased production of NO from rIFN-γ plus IXD-stimulated cells was almost completely inhibited by pre-treatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor kappa B (NF-κB). Furthermore, treatment with IXD alone or rIFN-γ plus IXD in peritoneal macrophages caused a significant increase in tumor necrosis factor-α (TNF-α) production. PDTC decreased TNF-α production induced by IXD significantly. These findings demonstrate that IXD increases the production of NO and TNF-α by rIFN-γ-primed macrophages and suggest that NF-κB plays a critical role in mediating these effects of IXD.

Disodium cromoglycate inhibits production of immunoglobulin E.

Disodium cromoglycate (DSCG) has been shown to inhibit the release of mediators from mast cells. In the present study, the effect of DSCG on active anaphylactic reaction was studied in mice. DSCG dose-dependently inhibited the active systemic anaphylactic reaction and serum immunoglobulin(Ig)E production induced by immunization with ovalbumin, Bordetella pertussis toxin and aluminum hydroxide gel. DSCG strongly inhibited IL-4-dependent IgE production by lipopolysaccharide-stimulated murine whole spleen cells. In the case of U266 human IgE-bearing B cells, DSCG also showed an inhibitory effect on the IgE production. These results suggest that DSCG has an anti-anaphylactic activity by inhibition of IgE production from B cells.

Expression of Protein Kinase C Genes in Normal (+/+) and W Mutant Alleles (Wsh/Wsh, W/Wv) Mice Testes

Abstract In the present study, we investigated the expression of mRNA of protein kinase C (PKC) isoenzymes (α, β, γ, δ, ε, ξ, and θ) in normal (+/+) and W mutant alleles mice testes. In +/+ mice testes, abundant expression of PKCδ and PKCθ was observed, while other PKCs (α, β, γ, ε, ξ, and η) generally were not detected by Northern blotting. The PKCδ and PKCθ isoenzymes demonstrated a distinctive cellular distribution when evaluated by in situ hybridization. We have previously shown that PKCδ gene was selectively expressed in spermatid of +/+ testes. Here we show that PKCδ gene is also present in spermatid of Wsh/Wsh mice testes and PKCθ gene was present in interstitial cells of +/+, Wsh/W sh, and W/Wv mice testes. These studies provide the evidence of selective cell distributions of the PKC isoenzymes and suggest that PKC has the functional significance in testes.

Inhibition of heat shock-induced apoptosis by peppermint oil in astrocytes.

Exposure to environmental stresses and toxins is linked to the pathogenesis of neuropsychiatric disorders. Astrocytes, the most abundant glial-cell type in the brain, are considered to have physiological and pathological roles in neuronal activities. We have investigated whether peppermint oil inhibits heat shock-induced apoptosis of astrocytes. We found that peppermint oil inhibits the heat shock-induced apoptosis in both human astrocyte CCF-STTG1 cells and rat astrocytes. Pretreatment of the cells with peppermint oil inhibited the heat shock-induced DNA fragmentation and condensation of nuclear chromatin. Peppermint oil also inhibited the caspase-3 activation and poly-ADP-ribose polymerase fragmentation in CCF-STTG1 cells. These results suggest that peppermint oil may modulate the apoptosis of astrocytes via the activation of the caspase-3.

PHOSPHATIDYLINOSITOL 3-KINASE REGULATES PROLIFERATION OF RAW 264.7 MACROPHAGES

Phosphatidylinositol 3-kinase (PI3-kinase) is an enzyme that acts as a direct biochemical link between a novel phosphatidylinositol pathway and a number of proteins containing intrinsic or associated kinase activities. Here we demonstrate that wortmannin, PI3-kinase inhibitor, decreases the proliferation of RAW 264.7 macrophages and that another structurally unrelated inhibitor of PI3-kinase, LY294002, also inhibits the proliferation. These results indicate a possible involvement of PI3-kinase in RAW 264.7 macrophages growth regulation. Wortmannin stimulation of RAW 264.7 macrophages is followed by sustained expression of the mRNA of c-fos and a transient expression of the mRNA of c-jun. We also show that the wortmannin and LY294002 induce a cell cycle arrest in asynchronously growing cells leading to an inhibition of cell proliferation after 12 h of treatment. In addition, wortmannin or LY294002 inhibited the phorbol 12-myristate 13-acetate-induced macrophages proliferation potently. These results suggest that PI3-kinase plays an important role in growth regulation of RAW 264.7 macrophages and that protein kinase C is a down stream effector of PI3-kinase.