• Restorative Dentistry and Endodontics
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• v.44 no.2
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• pp.13.1-13.9
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• 2019

Objectives: This study evaluated the effect of dentin pretreatment with silver nanoparticles (SNPs) and chlorhexidine (CHX) on the microshear bond strength (${\mu}SBS$) durability of different adhesives to dentin. Materials and Methods: Occlusal surfaces of 120 human molars were ground to expose flat dentin surfaces. The specimens were randomly assigned to six groups (n = 20). Three groups (A, B, and C) were bonded with Adper Single Bond 2 (SB) and the other groups (D, E, and F) were bonded with Clearfil SE Bond (SEB). Dentin was pretreated with CHX in groups B and E, and with SNPs in groups C and F. The specimens were restored with Z250 composite. Half of the bonded surfaces in each group underwent ${\mu}SBS$ testing after 24 hours and the other half was tested after 6 months of water storage. Results: SNP application was associated with a higher ${\mu}SBS$ than was observed in the CHX and control groups for SEB after 24 hours (p < 0.05). A significantly lower ${\mu}SBS$ was observed when no dentin pretreatment was applied compared to dentin pretreatment with CHX and SNPs for SB after 24 hours (p < 0.05). The ${\mu}SBS$ values of the 6-month specimens were significantly lower than those obtained from the 24-hour specimens for all groups (p < 0.05). This decrease was much more pronounced when both adhesives were used without any dentin pretreatment (p < 0.05). Conclusions: SNPs and CHX reduced the degradation of resin-dentin bonds over a 6-month period for both adhesive systems.

• KSBB Journal
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• v.22 no.1
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• pp.43-47
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• 2007

The effect of surfactant on the hydrolysis of used newspaper was investigated. The most suitable surfactant for the pretreatment stage was found to be NP-series surfactants among 9 kinds of non ionic surfactants. Process parameters such as surfactant concentration, mixing speed, pretreatment temperature and time were tested to optimize for maximum digestibility and 0.5%, 100rpm, 30$^{\circ}C$, and 1 h were found to be optimum, respectively. In order to maximize digestibility, substrate was pretreated with NP-20 and then the pretreated substrate was hydrolyzed by adding TW-80. The effect of surfactant on the hydrolysis of previously surfactant-pretreated newspaper was marginal. Therefore, the digestibility with the addition order of enzyme and surfactant was investigated by using surfactant only in hydrolysis stage. The results show that digestibility was more lowered as the surfactant addition after adding enzyme to substrate was more delayed.

• The Journal of Advanced Prosthodontics
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• v.3 no.1
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• pp.16-19
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• 2011

PURPOSE. Purpose of this study was to evaluate effect of two surface treatments, sandblasting and monomer treatment, on tensile bond strength between two long term resilient liners and poly (methyl methacrylate) denture base resin. MATERIALS AND METHODS. Two resilient liners Super-Soft and Molloplast-B were selected. Sixty acrylic resin (Trevalon) specimens with cross sectional area of $10{\times}10$ mm were prepared and divided into two groups of 30 specimens each. Each group was surface treated (n = 10) by sandblasting (250 ${\mu}$ alumina particles), monomer treatment (for 180 sec) and control (no surface treatment). Resilient liners were processed between 2 poly(methyl methacrylate) surfaces, in the dimensions of $10{\times}10{\times}3$ mm. Tensile strength was determined with Instron Universal testing machine, at a crosshead speed of 5 mm/min; and the modes of failure (adhesive, cohesive or mixed) were recorded. The data were analyzed using one-way ANOVA, followed by Tukey HSD test (${\alpha}$= 0.05). RESULTS. Monomer pretreatment of acrylic resin produced significantly higher bond strengths when compared to sandblasting and control for both resilient liners (P < .001). Sandblasting significantly decreased the bond strength for both the liners when compared to monomer pretreatment and control (P < .001). Mean bond strength of Super-Soft lined specimens was significantly higher than Molloplast-B in various surface treatment groups (P < .05). CONCLUSION. Surface pretreatment of the acrylic resin with monomer prior to resilient liner application is an effective method to increase bond strength between the base and soft liner. Sandblasting, on the contrary, is not recommended as it weakens the bond between the two.

• Journal of Korean Neurosurgical Society
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• v.38 no.4
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• pp.287-292
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• 2005

Objective : Kainic acid[KA] enhances the expression of nitric oxide synthase, increases nitric oxide[NO], and thus evokes epileptic convulsion, which results in neuronal damage in the rat brain. NO may stimulate cyclooxygenase type-2 [COX-2] activity, thus producing seizure and neuronal injury, but it has also been reported that KA-induced seizure and neurodegeneration are aggravated on decreasing the COX-2 level. This study was undertaken to investigate whether the suppression of NO using the NOS inhibitor, N-nitro-L-arginine methyl ester[L-NAME], suppresses or enhances the activity of COX-2. Methods : Silver impregnation and COX-2 immunohistochemical staining were used to localize related pathophysiological processes in the rat forebrain following KA-induced epileptic convulsion and L-NAME pretreatment. Post-injection survival of the rat was 1, 2, 3days and 2months, respectively. Results : After the systemic administration of KA in rats, neurodegeneration increased with time in the cornu ammonis [CA] 3, CA 1 and amygdala, as confirmed by silver impregnation. On pretreating L-NAME, KA-induced neuronal degeneration decreased. COX-2 enzyme activities increased after KA injection in the dentate gyrus, CA 3, CA 1, amygdala and pyriform cortex, as determined by COX-2 staining. L-NAME pretreatment prior to KA-injection, caused COX-2 activities to increase compared with KA- injection only group by 1day and 2days survival time point. Conclusion : These results suggest that L-NAME has a neuroprotective effect on KA-induced neuronal damage, especially during the early stage of neurodegeneration.

• Korean Journal of Veterinary Research
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• v.42 no.4
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• pp.475-483
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• 2002

We performed this study to determine the effect of Korean favorite teas (green tea, ginseng tea, coffee and barley tea) on jejunal crypt survival, endogenous spleen colony formation and apoptosis in jejunal crypt cells of mice irradiated with high and low dose of ${\gamma}$-radiation. Jejunal crypts were protected by pretreatment of green tea (P.O.: 1.25% water extract, for 7 days before irradiation., I.P.: 50 mg/kg of body weight, at 12 and 36 hours before irradiation, p<0.01) or ginseng (I.P.: 50 mg/kg of body weight, at 12 and 36 hours before irradiation, p<0.05). Green tea (p<0.05) or ginseng (p<0.05) administration before irradiation (I.P. at 12 and 36 hours before irradiation) resulted in an increase of t formation of endogenous spleen colony. The frequency of radiation-induced apoptosis was also reduced by pretreatment of green tea (P.O.: p<0.005, I.P.: p<0.05), pretreatment of ginseng (P.O.: p<0.005, I.P.: p<0.005) or posttreatment of ginseng (I.P.: 50 mg/kg of body weight, at 30 minutes after irradiation, p<0.05). Treatment with coffee or barley tea showed no significant modifying effects on the radiation-induced damages. These results indicated that green tea and ginseng might be a useful radioprotector, especially since it is a relatively nontoxic natural product. Further studies are needed to characterize better the promotion nature of green tea, ginseng and its components.

• Korean Journal of Weed Science
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• v.2 no.2
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• pp.141-145
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• 1982

In order to determine the possibility of reducing rice injury caused by CNP and butachlor application, the effects of IAA seed presoaking on CNP and butachlor action against early growth of rice seedlings were investigated under flooded direct-seeding and dry-seeded conditions. CNP and butachlor injury to rice was reduced by soaking rice seeds at 0.1, 1.0 and 10ppm of IAA solution for 36 hours before seeding under flooded condition and thus shoot length and dry weight of rice seedlings increased compared with those of IAA untreated seedlings. IAA seed pretreatment also overcame the inhibitory effect of CNP and butachlor under dry-seeded condition. Effect on reducing rice injury by IAA pretreatment was more remarkable when CNP applied under dry seeded condition and butachlor under flooded condition.

• IMMUNE NETWORK
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• v.4 no.2
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• pp.100-107
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• 2004

Background: The fruit of Rubus coreanus (RC), a perennial herb, has been cultivated for a long time as a popular vegetable. The anti-allergy mechanism of RC is unknown. The purpose of this study is to investigate the inhibitory effect of RC on compound 48/80- or anti-DNP IgE-induced mast cell activation. Methods: For this, influences of RC on the compound 48/80-induced degranulation, histamine release, calcium influx and the change of the intracellular cAMP (cyclic adenosine-3',5' monophosphate) levels of rat peritoneal mast cells (RPMC) and on the anti-DNP IgE-induced histamine release of RPMC were observed. Results: The pretreatment of RC inhibited compound 48/80-induced degranulation, histamine release and intracelluar calcium uptake of RPMC. The anti-DNP IgE-induced histamine release of RPMC was significantly inhibited by pretreatment of RC. The RC increased the level of intracellular cAMP of RPMC, and the pretreatment of RC inhibited compound 48/80-induced decrement of intracellular cAMP of RPMC. Conclusion: These results suggest that RC contains some substances with an activity to inhibit the compound 48/80- or anti-DNP IgE-induced mast cell activitation. The inhibitory effects of RC are likely due to the stabilization of mast cells by blocking the calcium uptake and enhancing the level of intracellular cAMP.

• Toxicological Research
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• v.11 no.2
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• pp.247-252
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• 1995

To evaluate the effect of xanthine oxidase on liver injury by $CCl_4$, liver damage was induced both in allopurinol pretreated rats (500 mg/kg. ip) and control group by twice intraperitoneal injection of $CCl_4$ (0.1 ml/100 g body wt. 50% in olive oil) at interval of one day. Increases in the levels of serum alanine aminotransferase and liver weight/body weight (%) by $CCl_4$ were significantly smaller inallopurinol pretreated rats than in control whereas the hepatic microsomal glucose-6-pholphatase activities were significantly higher in allopurinol pretreated rats than control group by $CCl_4$ treatment. These results indicates that allopurinol pretreatment may reduce the liver damage in $CCl_4$ intoxicated rats. In rats either with $CCl_4$or not, hepatic type O xanthine oxidase activities were significantly reduced by allopurinol pretreatment and the increasing rate of these enzymes to each control was remarkably lower in allopurinol pretreated rats than control. Liver cytosolic protein contents and aniline hydroxylase, aminopyrine demethylase activities were higher in allopurinol pretreated rats than coirol rats when animals were treated with $CCl_4$. On the other hand, neither allopurinol pretreated nor $CCl_4$ treatment caused any significant changes in hepatic superoxide dismutase and catalase activities. Hepatic glutathione contents were higher in $CCl_4$-treated rats than control, but no significant changes were found in both between the allopurinol treated rats and $CCl_4$-treated rats pretreated with allopurinol, and glutathione and glutathione S-transferase activities were significantly reduced in $CCl_4$-treated rats than control whereas these enzyme activities showed on significant change in both between allopurinel treated and $CCl_4$-treated rats pretreated with allopurinol. It is concluded that xanthine oxidase reaction system augment $CCl_4$ induced liver injury via even oxygen free radical system.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.17 no.1
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• pp.82-93
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• 2004

Recently many efforts were focused to understanding the mechanical insights of melanogenesis to develop the agents for hyper-pigmentation and hypo-pigmentation. In the melanin biosynthetic pathway, tyrosinase is the rate limiting enzyme, and ${\alpha}$-melanocyte stimulating hormone(MSH) or cAMP-elevating agents stimulate melanogenesis and enhance the melanin synthesis and the tyrosinase activity. The author has analyzed the effects of Radix Trichosanthis on the basal Melanogenic activities of Bl6/F10 mouse melanoma cells, and on the ${\alpha}$-MSH or forskolin-induced melanogenesis. Radix Trichosanthis alone markedly suppressed melanin content and tyrosinase activity in a dose-dependent manner. Pretreatment of the cells with Radix Trichosanthis also suppressed the increase of ${\alpha}$-MSH(10 nM) or forskolin(20 ${\mu}$M)-induced melanin content and tyrosinase activity. The decrease in the tyrosinase activity was paralled by a decrease in the abundance of tyrosinase protein and tyrosinase promoter activity. Pretreatment of the cells with Radix Trichosanthis also inhibited the increase of forskolin(20 ${\mu}$M) induced the amount of tyrosinase protein and tyrosinase promoter activity. The results of DOPA staining revealed that pretreatment of the cells with Radix Trichosanthis showed less intensity than B16 melanoma cells stimulated with ${\alpha}$-MSH or forskolin. These results suggest that Radix Trichosanthis inhibits melanogenesis and abrogates ${\alpha}$-MSH and cAMP-induced melanogenesis in B16 melanoma cells.

• The Korean Journal of Physiology and Pharmacology
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• v.10 no.1
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• pp.25-30
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• 2006

Lysophosphatidylcholine (LPC), which accumulates in atherosclerotic arteries, has been reported to inhibit endothelium-dependent relaxation (EDR) in many different species. However, the underlying mechanism of LPC-induced inhibition of EDR is still uncertain. In the present study, we measured simultaneously both isometric tension and cytosolic free $Ca^{2+}$ ($[Ca^{2+}]_i$) in rabbit carotid strips, and examined the effect of LPC on tension and $[Ca^{2+}]_i$. In carotid strips with intact-endothelium, high $K^+$ (70 mM) increased both tension and $[Ca^{2+}]_i$, and cumulative addition of acetylcholine (ACh) from 0.1 to $10{\mu}M$ induced dose dependent increase of $[Ca^{2+}]_i$ with concomitant relaxation. In the presence of L-NAME (0.1 mM), ACh increased $[Ca^{2+}]_i$ without affecting the amplitude of high $K^+-induced$ tension. These ACh-induced change of $[Ca^{2+}]_i$ and tension was abolished by removal of endothelium or 10 nM 4-DAMP (muscarinic receptor antagonist) pretreatment. Pretreatment of LPC ($10{\mu}M$) inhibited ACh ($10{\mu}M$)-induced change of tension and $[Ca^{2+}]_i$ in endothelium-intact carotid artery. On the other hand, LPC had no effect on ACh-induced change of tension and $[Ca^{2+}]_i$ in endothelium denuded artery. In $Ca^{2+}$-free external solution, ACh transiently increased $[Ca^{2+}]_i$, and pretreatment of LPC significantly inhibited ACh-induced transient $[Ca^{2+}]_i$ change. Based on the above results, it may be concluded that LPC inhibits the ACh-induced $[Ca^{2+}]_i$ change through inhibition of $Ca^{2+}$ mobilization in vascular endothelial cells, resulting in decreased production of NO and concomitant inhibition of endotheliumdependent vascular relaxation.