• Fisheries and Aquatic Sciences
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• v.7 no.2
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• pp.58-63
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• 2004

Five urease-positive Vibrio parahaemolyticus strains were isolated from Kamak Bay in Yeosu in 2002 and 2003. V. parahaemolyticus YKB4 and YKB14 were isolated from seawater, YFB20 from black rockfish (Sebastes schlegeli), and YFO2l and YFO22 from olive flounder (Paralichthys olivaceus). The five urease-positive strains (YKB4, YKB14, YFB20, YFO21, and YFO22) did not show hemolysin and protease activity, while they did alter in color (to red) as the bacteria grew in the urea broth medium. All samples showed identical biochemical characteristics as a reference strain, V. parahaemolyticus KCTC2471, except in urease production. The five urease-positive strains showed urease activities at a mid stationary phase, and their activity was maximal in the late stationary phase of their culture supernatant. The addition of urea to the Luria-Bertani (LB) broth medium significantly affected the initial production of urease of V. parahaemolyticus isolates. Mortality by urease-positive V. parahaemolyticus YKB4, YKB14, YFO2l, and YFO22 was significantly high, being$60-80\%$, while YFB20 only reflected a rate of $20\%$. Protease-positive V. parahaemolyticus FM39 and FM50 showed a $40\%$ and $60\%$ mortality rate, respectively. However, hemolysin-positive V. parahaemolyticus had no mortality, like the non-pathogenic V. parahaemolyticus KCTC2471, while V. vulnificus resulted in a $40\%$ mortality rate. Injection with urease-positive V. parahaemolyticus strains showed mortality within 12 hrs in mice, and the strains could be isolated from the dead mice.

• Restorative Dentistry and Endodontics
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• v.30 no.4
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• pp.335-343
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• 2005

Hemolytic property is a specific feature of bacteria to obtain iron which is essential for its survival in host tissues. Therefore, it is thought to be one of several factors of virulence. The purpose of this study was to investigate the hemolytic properties of Prevotella nigrescens isolated from the teeth diagnosed as pulp necrosis and apical periodontitis under the presence of hemolysin inhibitors such as $NaN_3$ and dithiothreitol. heat, various pH and cultural conditions. The results were as follows; 1. Clinically isolated P. nigrescens strains and standard P. nigrscens ATCC 33563 showed hemolytic activity. 2. P. nigrescens showed higher hemolytic activity against human erythrocytes than sheep or horse erythrocytes. 3. $NaN_3$ and dithiothreitol (DTT) reduced the hemolytic activity of P. nigrescens in a dose dependent manner (p<0.05). 4. Optimal pH for the maximum hemolytic activity of P. nigrescens was 4.0 and the hemolysin was stable under the $50^{\circ}C$, but the hemolytic activity was significantly decreased at $95^{\circ}C$. 5. P. nigrescens cultured in $10\%\;CO_2$ condition showed higher hemolytic activity than the bacteria cultured in the anaerobic condition.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.196.1-196.1
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• 2003

Cinnamic acid derivatives(CAD) originating from vegetable kingdom have some biological activity. Effect of CAD on reversed cutaneous anaphylaxis (RCA) and hemolysin (HY) titer were studied in rats. Experiments were carried out to determine RCA as the skin edema induced at 2 hours after injection of 0.05 $m\ell$/site of anti-rat serum rabbit serum. Drugs were orally administered at one hour before antigen challenge. (omitted)

• The Journal of Pediatrics of Korean Medicine
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• v.21 no.1
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• pp.189-209
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• 2007

Objectives : In order to study the effect of Dangkwiyughwangtang and Okbyoungpoongsangamibang on the immune response induced by methotrexate in mice. Method : Delayed type of hypersensitivity, hemagglutinin titer, hemolysin titer, rosette forming cells, phagocytic activity for immune response, lymphocyte transformation, and productivity of Interleukin-2 were measured. Results : Body weight decreasing was significantly inhibited as compared with control group in both the Dangkwiyughwangtang and Okbyoungpoongsangamibang groups. Delayed type of hypersensitivity was significantly increased as compared with control group in both groups Hemagglutinin titer was significantly increased as compared with control group in both groups. Hemolysin titer was significantly increased as compared with control group in the Okbyoungpoongsangamibang group. Rosette forming cells were significantly increased as compared with control group in both groups. Phagocytic activity for immune response was slightly decreased in the Dangkwiyughwangtang group and slightly increased in the Okbyoungpoongsangamibang group insignificantly as compared with the control group. Lymphocyte transformation was significantly increased as compared with the control group in both the Dangkwiyughwangtang and Okbyoungpoongsangamibang groups. Productivity of Interleukin-2 was significantly increased as compared with the control group in both the Dangkwiyughwangtang and Okbyoungpoongsangamibang groups. Conclusion : Both the Dangkwiyughwangtang and Okbyoungpoongsangamibang groups enhance immunity in mice.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.443-450
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• 1995

Listeria monocrogenes has been increasingly recognized as an important food poisoning and pathogenic bacterium which is Gram positive, non spore forming and facultative anaerobic rod shape. Bacteriological and physiological characterization of L. monocytogenes YM-7 isolated from a patient was performed. Optimum growth condition of 1. monocytogenes YM-7 was at $37^{\circ}$, pH 8.0 and $0\%$ sodium chloride in tryptic soy broth, and then it grew pretty well in the range of $8-40^{\circ}C,\;pH 5.0-10.0\;and\;up\;to\;7\%$ of sodium chloride in the medium. The highest hemolysin activity of hemolysin produced by L. monocytogenes YM-7 was shown in the stationary phase of its growth. Hemolysin produced by the isolated strain was stable at $4^{\circ}C\;and\;pH\;6.0-8.0, while it was gradually unstable by increasing the storage temperature.

• The Journal of the Korean Society for Microbiology
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• v.35 no.3
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• pp.251-261
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• 2000

V. vulnificus is an estuarine bacterium which causes septicemia and shock in susceptible patients. The organism produces a hemolytic cytolysin (VvH), which has a membrane damaging effect on erythrocytes. To clarify the mechanisms by which VvH might contribute to virulence, we examined its effect on macrophages. When mouse peritoneal macrophages were harvested and co-cultured with hemolysin-positive V. vulnificus strains (100 bacteria/cell), about 60% of the macrophages were killed; macrophages were not killed when co-cultured V. vulnificus strain CVD 707, a VvH-negative deletion mutant. Exposure of macrophages to filtered culture supernatants (2.5 HU/ml) and purified VvH (3 HU/ml) resulted in an increase in dead cells (80 and 90%, respectively), as determined by the trypan blue dye exclusion method and LDH release from macrophages was also increased (70 and 65.5%, respectively). The cytotoxic effect of VvH on macrophages was both the dose- and time-dependent. The VvH caused damage to the macrophage membrane and was blocked significantly by preincubation with cholesterol (p<0.01). Fetal bovine serum showed remarkable inhibition of VvH synthesis by V. vulnificus and inhibited VvH activity in culture supernatant. Cell viability was increased by 35% (p<0.01) and LDH release decreased by 28% (p<0.01) when macrophages were incubated with V. vulnificus (100 bacterial cell) in DMEM-10% FBS for 2 hr. Bacterial clearance activity of mice against V. vulnificus CVD 707 was decreased by pretreatment with 10 HU of VvH. This result suggests that the VvH can impair the membrane of macrophages and may playa role in the pathogenesis of V. vulnificus septicemia.

• The Journal of Pediatrics of Korean Medicine
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• v.8 no.1
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• pp.39-58
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• 1994

Even though appropriate immune response is necessary for the survival of the individual, excessive or insufficient immune response might cause autoimmune or allergic disease respectively. So the immune response must be controlled to the degree that is beneficial for the well being of the individual. This study was undertaken to know the effects of Junsibaekchulsan(JB) on the immune system od the mouse. For the evalulation of the cell-mediated immunity(CMI), delayed-type hypersensitivity against dinitrofluorobenzene(DNFB) were measured, and humoral immunity, hemagglutinin and hemolysin titers against SRBCs(sheep red blood cells) were measured, and rosette formation of spleen cells with SRBCs were measured. For the evaluation of innate immunity, phagocytic activity of macrophages, natural killer cell activity, and reactive nitrogen and oxygen intermediates were measured. The results are as follows: 1. The administration of JB depressed the antibody formation (hemagglutinin and hemolysin) against SRBCs. 2. The administration of JB did not affect the delayed-type hypersensitivity against DNFB. 3. The administration of JB did not affect the cytotoxic activity of natural killer cells. 4. The administration of JB increased the phagocytic activity of macrophages. 5. The administration of JB increased the rosette formating cells of the spleen cells. 6. The exposure of JB induced the secretion of reactive nitrogen intermediates but administration of JB deperssed the production of reactive oxygen intermediates. Administration of JB selectively depressed the humoral immune response without affecting CMI and innate immunity. These results of JB on the immune system might be useful for the treatment of such.

• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.596-602
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• 2016

Staphylococcus aureus, like other gram-positive pathogens, has evolved a large repertoire of virulence factors as a powerful weapon to subvert the host immune system, among which alpha-hemolysin (Hla), a secreted pore-forming cytotoxin, plays a preeminent role. We observed a concentration-dependent reduction in Hla production by S. aureus in the presence of sub-inhibitory concentrations of isorhamnetin, a flavonoid from the fruits of Hippophae rhamnoides L., which has little antibacterial activity. We further evaluate the effect of isorhamnetin on the transcription of the Hla-encoding gene hla and RNAIII, an effector molecule in the agr system. Isorhamnetin significantly down-regulated RNAIII expression and subsequently inhibited hla transcription. In a co-culture of S. aureus and lung cells, topical isorhamnetin treatment protected against S. aureus-induced cell injury. Isorhamnetin may represent a leading compound for the development of anti-virulence drugs against S. aureus infections.

• Journal of Microbiology
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• v.44 no.2
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• pp.226-232
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• 2006

Swarming has proven to be a good in vitro model for bacterial surface adherence and colonization, and the swarming differentiation of a bacterium has been shown to be coupled with changes in the expression of virulence factors associated with its invasiveness, particularly in the early stages of infection. In this study, we attempted to determine whether the expression of vvhA, which encodes for hemolysin/cytolysin (VvhA), is either upregulated or downregulated during the swarming differentiation of V. vulnificus. The insertional inactivation of vvhA itself exerted no detectable effect on the expression of V. vulnificus swarming motility. However, in our lacZ-fused vvhA transcriptional reporter assay, vvhA expression decreased in swarming V. vulnificus as compared to non-swarming or planktonic V. vulnificus. The reduced expression of vvhA in swarming V. vulnificus increased as a result of the deletional inactivation of luxS, a gene associated with quorum sensing. These results show that vvhA expression in swarming V. vulnificus is downregulated via the activity of the LuxS quorum-sensing system, suggesting that VvhA performs no essential role in the invasiveness of V. vulnificus via the adherence to and colonization on the body surfaces required in the early stages of the infection. However, VvhA may playa significant role in the pathophysiological deterioration occurring after swarming V. vulnificus is differentiated into planktonic V. vulnificus.

• Journal of Microbiology and Biotechnology
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• v.31 no.9
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• pp.1200-1209
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• 2021

Sepsis is an acute inflammatory response that leads to life-threatening complications if not quickly and adequately treated. Cytolysin, hemolysin, and pneumolysin are toxins produced by gram-positive bacteria and are responsible for resistance to antimicrobial drugs, cause virulence and lead to sepsis. This work assessed the effects of aloe-emodin (AE) and photodynamic therapy (PDT) on sepsis-associated gram-positive bacterial toxins. Standard and antibiotic-resistant Enterococcus faecalis, Staphylococcus aureus, and Streptococcus pneumonia bacterial strains were cultured in the dark with varying AE concentrations and later irradiated with 72 J/cm^-2 light. Colony and biofilm formation was determined. CCK-8, Griess reagent reaction, and ELISA assays were done on bacteria-infected RAW264.7 cells to determine the cell viability, NO, and IL-1β and IL-6 pro-inflammatory cytokines responses, respectively. Hemolysis and western blot assays were done to determine the effect of treatment on hemolysis activity and sepsis-associated toxins expressions. AE-mediated PDT reduced bacterial survival in a dose-dependent manner with 32 ㎍/ml of AE almost eliminating their survival. Cell proliferation, NO, IL-1β, and IL-6 cytokines production were also significantly downregulated. Further, the hemolytic activities and expressions of cytolysin, hemolysin, and pneumolysin were significantly reduced following AE-mediated PDT. In conclusion, combined use of AE and light (435 ± 10 nm) inactivates MRSA, S. aureus (ATCC 29213), S. pneumoniae (ATCC 49619), MDR-S. pneumoniae, E. faecalis (ATCC 29212), and VRE (ATCC 51299) in an AE-dose dependent manner. AE and light are also effective in reducing biofilm formations, suppressing pro-inflammatory cytokines, hemolytic activities, and inhibiting the expressions of toxins that cause sepsis.