• Restorative Dentistry and Endodontics
• /
• v.27 no.5
• /
• pp.543-551
• /
• 2002

Nitric oxide (NO) is a small molecule (mol. wt. 30 Da) and oxidative free radical. It is uncharged and can therefore diffuse freely within and between cells across membrane. Such characteristics make it a biologically important messenger in physiologic processes such as neurotransmission and the control of vascular tone. NO is also highly toxic and is known to acts as a mediator of cytotoxicity during host defense. NO is synthesized by nitric oxide synthase (NOS) through L-arginine/nitric oxide pathway which is a dioxygenation process. NO synthesis involves several participants, three co-substrates, five electrons, five co-factors and two prosthetic groups. Under normal condition, low levels of NO are synthesized by type I and III NOS for a short period of time and mediates many physiologic processes. Under condition of oxidant stress, high levels of NO are synthesized by type II NOS and inhibits a variety of metabolic processes and can also cause direct damage to DNA. Such interaction result in cytostasis, energy depletion and ultimately cell death. NO has the potential to interact with a variety of intercellular targets producing diverse array of metabolic effects. It is known that NO is involved in hemodynamic regulation, neurogenic inflammation, re-innervation, management of dentin hypersensitivity on teeth. Under basal condition of pulpal blood flow, NO provides constant vasodilator tone acting against sympathetic vasoconstriction. Substance P, a well known vasodilator, was reported to be mediated partly by NO, while calcitonin-gene related peptide has provided no evidence of its relation with NO. This review describes the roles of NO in dental pulp in addition to the known general roles of it.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
• /
• v.11 no.1
• /
• pp.1-22
• /
• 1998

During the last few years, nitric oxide(NO) as a potent macrophage-derived effector molecule against a variety of bacteria, parasites, and tumors has received increasing attention. More recent studies suggest that NO also has antiviral effects in both murine and human cells. The objective of the current study was to determine the effect of Yongdamsagantang(YST) on the production of NO. Stimulation of mouse peritoneal macrophages with YST after the treatment of recombinant $interferon-{\gammer}(rlFN-{\gammer})$ resulted in the increased NO synthesis. YST had no effect on NO synthesis by itself. When YST was used in combination with $rIFN-{\gammer}$, there was a marked cooperative induction of NO synthesis in a dose-dependent manner. The optimal effect of YST on NO synthesis was shown 6 hour after treatment with $rIFN-{\gammer}$. This increase in NO synthesis was reflected as increased amount of inducible NO synthase(iNOS) protein. NO production was inhibited by $N^G-monomethyl-L-arginine$. The increased production of NO from $rIFN-{\gammer}$ plus YST-stimulated cells was decreased by the treatment with staurosporin. In addition, synergy between $rIFN-{\gammer}$ and YST was mainly dependent on YST-induced tumor necrosis $factor-{\alpha}(TNF-{\alpha})$ secretion. These results suggest that the capacity of YST to increase NO production from $rIFN-{\alpha}-primed$ mouse peritoneal macrophages is the result of YST-induced $TNF-{\alpha}$ secretion.

• Tuberculosis and Respiratory Diseases
• /
• v.45 no.6
• /
• pp.1167-1177
• /
• 1998

Background : Pulmonary tuberculosis is one of the diseases characterized granuloma formation which was controlled by cellular immune reactions. In the process of granulomatous changes, activated alveolar macrophages and T lymphocytes secrete many cytokines including interleukin-1 (IL-1), tumor necrosis factor-alpha(TNF-$\alpha$), interferon-gamma(IFN-$\gamma$) which mediate inflammatory reactions. Intercelluar adhesion molecule-1(ICAM-1) also known to major role player in inflammatory processes, and increased cellular expressions when endothelial cell was stimulated by IL-1, TNF and IFN. Method : To evaluate relationships among cellular immune reactions and clinical stages, pulmonary tuberculosis patients were classified into three groups according to their clinical stages including minimal, moderate and far advanced tuberculosis. TNF-$\alpha$ IFN-$\gamma$, sICAM-1 (soluble form of ICAM-1) were measured at the time of diagnosis and after 6-months anti-tuberculosis medications by radioimmuno assay or enzyme linked immunosolvent assay. Result : TNF-$\alpha$, IFN-$\gamma$, sICAM-1 were significantly increased in moderate and far advanced pulmonary tuberculosis patients but no meaningful changes in minimal staged patients. 6-months anti-tuberculosis medications reduced serum sICAM-1 levels significantly, related to clinical improvement but no significant changes were found in the serum levels of TNF-$\alpha$ and IFN-$\gamma$. In the point of correlations. positive ones revealed between TNF-$\alpha$ and sICAM-1, also between IFN-$\gamma$ and sICAM-1 but no correlation between TNF-$\alpha$ and IFN-$\gamma$. Conclusion : Measurement of serum sICAM-1 could be useful parameter to evaluate the severity of pulmonary tuberculosis and to monitor disease activities during anti-tuberculosis medications.

• Korean Journal of Microbiology
• /
• v.50 no.2
• /
• pp.87-94
• /
• 2014

Nitric oxide (NO), which has been recognized as an integral molecule in maintaining homeostasis, plays an important role in host defense against microbes. NO has diverse antimicrobial mechanisms by directly and/or indirectly interacting with microbes. Under the circumstance that there is an urgent need for a new class of antimicrobial agents due to antibiotic resistance, much effort has been made to develop a NO-based antimicrobial agent. In order to make it possible, strategies to store and release NO in a controlled manner are required because NO has a gaseous property and a very short half-life. In this review, we described NO biochemistry and its mechanisms of antimicrobial activity. In additions, we introduced various NO-releasing systems that improve NO's antimicrobial activity.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.159-159
• /
• 2022

Nitric oxide (NO) is a versatile signaling molecule, which is not only involved in plant growth and development but also regulates biological processes in response to biotic and abiotic stresses. Exogenous application of NO regulates the endogenous level of nitric oxide in response to stress conditions and therefore, NO donors are frequently used for stress alleviation. However, NO has very short half-life along with high reactivity. Therefore, conventional NO donors are often disadvantageous due to the relative instability of NO. On the contrary, development of NO releasing nanoparticles is a potential technique for enhancing the availability of NO in plants. Therefore, our aim was to synthesize such potential NO releasing nanoparticles which may be useful for application in agriculture. We have prepared Chitosan encapsulated S-nitrosoglutathione nanoparticles (GSNONP) and tried it with different concentrations for basic research in Arabidopsis thaliana. Our results suggest that lower concentration of this nanoparticle is highly effective for better growth of plants whereas higher concentration produces toxicity that leads to plant death. We observed better growth of Arabidopsis thaliana at 1µM concentration of the GSNONP compared to free GSNO.

• BMB Reports
• /
• v.35 no.1
• /
• pp.116-126
• /
• 2002

Nitric oxide (NO), synthesized from L-arginine by NO synthases, is a small, lipophilic, diffusible, highly reactive molecule with dichotomous regulatory roles in many biological events under physiological and pathological conditions. NO can promote apoptosis (pro-apoptosis) in some cells, whereas it inhibits apoptosis (anti-apoptosis) in other cells. This complexity is a consequence of the rate of NO production and the interaction with biological molecules such as metal ion, thiol, protein tyrosine, and reactive oxygen species. Long-lasting overproduction of NO acts as a pro-apoptotic modulator, activating caspase family proteases through the release of mitochondrial cytochrome c into cytosol, up-regulation of the p53 expression, and alterations in the expression of apoptosis-associated proteins, including the Bcl-2 family. However, low or physiological concentrations of NO prevent cells from apoptosis that is induced by the trophic factor withdrawal, Fas, $TNF{\alpha}$/ActD, and LPS. The anti-apoptotic mechanism is understood on the basis of gene transcription of protective proteins. These include: heat shock protein, hemeoxygenase, or cyclooxygenase-2 and direct inhibition of the apoptotic executive effectors caspase family protease by S-nitrosylation of the cysteine thiol group in their catalytic site in a cell specific way. Our current understanding of the mechanisms by which NO exerts both pro- and anti-apototic action is discussed in this review article.

• Archives of Pharmacal Research
• /
• v.26 no.3
• /
• pp.244-251
• /
• 2003

Plant nutrients are believed to provide protection against various diseases including inflammation. Since interactions of the cell adhesion molecules are known to play important roles in mediating inflammation, inhibiting adhesion protein upregulation is a possible therapeutic target. In this study, the interacellular adhesion molecule-1 (ICAM-1) was induced in human umbilical endothelial cells (HUVECs) after stimulation with $TNF-{\alpha}$. In addition, alginate, ascorbic acid and allicin were demonstrated to inhibit the $TNF-{\alpha}$ induced expression of ICAM-1 on the HUVECs in a dose-dependent manner. These compounds also inhibited the production of NO and $H_2O_2$ induced by $TNF-{\alpha}$, which suggests that the inhibition of ICAM-1 expression by the three compounds may be due to the modulated production of the reactive oxygen/nitrogen components. Overall, these results indicate that these dietary components have a therapeutic potential in the treatment of various inflammatory disorders associated with an increase in endothelial leukocyte adhesion molecules.

• Journal of Periodontal and Implant Science
• /
• v.43 no.4
• /
• pp.191-197
• /
• 2013

Purpose: Nitric oxide (NO) is a short-lived bioactive molecule that is known to play an important role in the pathogenesis of periodontal disease. In the current study, we investigated the effect of the flavonoid quercetin on the production of NO in murine macrophages activated with lipopolysaccharide (LPS) from Prevotella intermedia, a pathogen related to inflammatory periodontal disease, and tried to elucidate the underlying mechanisms of action. Methods: LPS was isolated from P. intermedia ATCC 25611 cells by the standard hot phenol-water method. The concentration of NO in cell culture supernatants was determined by measuring the accumulation of nitrite. Inducible NO synthase (iNOS) and heme oxygenase-1 (HO-1) protein expression, phosphorylation of c-Jun N-terminal kinase (JNK) and p38, inhibitory ${\kappa}B$ $(I{\kappa}B)-{\alpha}$ degradation, and signal transducer and activator of transcription 1 (STAT1) phosphorylation were analyzed via immunoblotting. Results: Quercetin significantly attenuated iNOS-derived NO production in RAW246.7 cells activated by P. intermedia LPS. In addition, quercetin induced HO-1 protein expression in cells activated with P. intermedia LPS. Tin protoporphyrin IX (SnPP), a competitive inhibitor of HO-1, abolished the inhibitory effect of quercetin on LPS-induced NO production. Quercetin did not affect the phosphorylation of JNK and p38 induced by P. intermedia LPS. The degradation of $I{\kappa}B-{\alpha}$ induced by P. intermedia LPS was inhibited when the cells were treated with quercetin. Quercetin also inhibited LPS-induced STAT1 signaling. Conclusions: Quercetin significantly inhibits iNOS-derived NO production in murine macrophages activated by P. intermedia LPS via anti-inflammatory HO-1 induction and inhibition of the nuclear factor-${\kappa}B$ and STAT1 signaling pathways. Our study suggests that quercetin may contribute to the modulation of host-destructive responses mediated by NO and appears to have potential as a novel therapeutic agent for treating inflammatory periodontal disease.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.6
• /
• pp.892-898
• /
• 2005

A long, bis(monodentate), linking Schiff-base ligand L (py-CH=N-$C_6H_4$-N=CH-py) was prepared from 1,4-phenylenediamine and 3-pyridinecarboxaldehyde by the Schiff-base condensation. Ligand L has two terminal pyridyl groups capable of coordinating to metals through their nitrogen atoms. In contrast, the same reaction between 1,2-phenylenediamine and 3-pyridinecarboxaldehyde produced a mixture of imidazol isomers (2-pyridin-3-yl-1H-benzoimidazole), which are connected to one another by the N-H…N hydrogen bonding to form a tetramer. From Zn($NO_3)_2{\cdot}6H_2O$ and ligand L under various conditions, one discrete molecule, trans- [Zn($H_2O)_4L_2]{\cdot}(NO_3)_2{\cdot}(MeOH)_2$, and two 1-D zinc polymers, [Zn$(NO_3)(H_2O)_2(L)]{\cdot}(NO_3){\cdot}(H_2O)_2$ and [Zn(L) (OBC)($H_2O$)], were prepared. In ligand L, the N$\ldots$N separation between the terminal pyridyl groups is 13.994 $\AA$, with their nitrogen atoms at the meta positions (3,3’) in a trans manner. The corresponding N$\ldots$N separations in its compounds range from 13.853 to 14.754 $\AA$.

• BMB Reports
• /
• v.42 no.2
• /
• pp.106-112
• /
• 2009

The bio-complex "reaction pattern in vertebrate cells"(RiV) is mainly represented by characteristic exosome-like particles - probably as reaction products of cells to specific stress. The transcription factor NF-kappaB plays a central role in inflammation. We tested the hypothesis that RiV particle preparations (RiV-PP) reduce cellular adhesion molecule (CAM) expression (ICAM-1, VCAM-1, E-selectin) by the attenuation of NF-kappaB translocation in human umbilical vein endothelial cells (HUVEC). After 4 hours, pre-incubation of HUVEC with RiV-PP before stimulation with TNF-alpha significantly reduced ICAM-1 (65.5${\pm}$10.3%) and VCAM-1 (71.1${\pm}$12.3%) mRNA expression compared to TNF-alpha-treated cells (100%, n=7). ICAM-1 surface expression was significantly albeit marginally reduced in RiV/TNF-alpha- treated cells (92.0${\pm}$5.6%, n=4). No significant effect was observed on VCAM-1 surface expression. In RiV/TNF-alpha-treated cells (n=4), NF-kappaB subunits p50 (85.7${\pm}$4.1%) and p65 (85.0${\pm}$1.8%) nuclear translocation was significantly reduced. RiV-PP may exert an anti-inflammatory effect in HUVEC by reducing CAM mRNA expression via attenuation of p50 and p65 translocation.