• Preventive Nutrition and Food Science
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• 제1권2호
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• pp.269-277
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• 1996

Bacteriocins are proteins produced by a heterogeneous group of bacteria that have a bactericidal effect on closely related organisms. Recently, bacteriocins from lactic acid bacteria and other food-related organisms have been the subject of much research because of their potential as food biopreservatives. Various modifications of agar plate diffusion assays are the most widely used methods even though the limitations of such assays are generally recognized. The ability to obtain a concentrated crude preparation on bacteriocin by optimizing production parameters greatly simplifies recovery of bacteriocin on subsequent purification steps. Some studies performed to optimize bacteriocins have been purified to homogeneity, and the amino acid sequences of many of these purified bacteriocins have been determined. Obtaining characterization data on purified bacteriocin will minimize the risk of overlapping of research and confusion on identification of these compounds. Several me-chanisms leading to cell death have been hypothesized. These include depletion of the proton motive force(PMF) across the cell membrane: RNase and/or DNase activity within the sensitive cell; and pore formation and lysis of sensitive cells at the cell membrane.

• IMMUNE NETWORK
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• 제7권3호
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• pp.133-140
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• 2007

Background: It is well established that cross talk between natural killer (NK) cells and myeloid dendritic cells (DC) leads to NK cell activation and DC maturation. In the present study, we investigated whether type 1-polarized DC (DC1) matured in the presence of IFN-${\gamma}$ and type 2-polarized DC (DC2) matured in the presence of PGE2 can differentially activate NK cells. Methods: In order to generate DC, plastic adherent monocytes were cultured in RPMI 1640 containing GM-CSF and IL-4. At day 6, maturation was induced by culturing the cells for 2 days with cytokines or PGE2 in the presence or absence of LPS. Each population of DC was cocultured with NK cells for 24 h. The antigen expression on DC was analyzed by flow cytometry and cytokine production in culture supernatant was measured by ELISA or a bioassay for TNF-${\alpha}$ determination. NK cell-mediated lysis was determined using a standard 4h chromium release assay. Results: DC2, unlike DC1, had weak, if any, ability to induce NK cell activation as measured by IFN-${\gamma}$ production and cytolytic activity. DC2 were weakly stimulated by activated NK cells compared to DC1. In addition, IFN-${\gamma}$-primed mature DC appeared to be most resistant to active NK cell-mediated lysis even at a high NK cell/DC ratio. On the other hand, PGE2-primed DC were less resistant to feedback regulation by NK cells than IFN-${\gamma}$-primed mature DC. Finally, we showed that the differential effect of two types of DC population on NK cell activity is not due to differences in their ability to form conjugates with NK cells. Conclusion: These results suggest that different combinations of inflammatory mediators differentially affect the effector function of DC and, as a result, the function of NK cells, eventually leading to distinct levels of activation in adaptive immunity.

• Molecules and Cells
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• 제40권12호
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• pp.935-944
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• 2017

More than 50% of sepsis cases are associated with pneumonia. Sepsis is caused by infiltration of bacteria into the blood via inflammation, which is triggered by the release of cell wall components following lysis. However, the regulatory mechanism of lysis during infection is not well defined. Mice were infected with Streptococcus pneumoniae D39 wild-type (WT) and lipase mutant (${\Delta}lipA$) intranasally (pneumonia model) or intraperitoneally (sepsis model), and survival rate and pneumococcal colonization were determined. LipA and autolysin (LytA) levels were determined by qPCR and western blotting. S. pneumoniae Spd_1447 in the D39 (type 2) strain was identified as a lipase (LipA). In the sepsis model, but not in the pneumonia model, mice infected with the ${\Delta}lipA$ displayed higher mortality rates than did the D39 WT-infected mice. Treatment of pneumococci with serum induced LipA expression at both the mRNA and protein levels. In the presence of serum, the ${\Delta}lipA$ displayed faster lysis rates and higher LytA expression than the WT, both in vitro and in vivo. These results indicate that a pneumococcal lipase (LipA) represses autolysis via inhibition of LytA in a sepsis model.

• 한국가축번식학회지
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• 제15권3호
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• pp.179-187
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• 1991

This experiment was carried out to develop a new technique of identifying XX of XY-bearing bisected embryos prior to implantation by immunological method. H-Y antiserum prepared in inbred Wastar female rats by repeated immunization with spleen cells from males of the same strain. The reactivity of H-Y antibody was confirmed by culturing mouse embryos in the medium containing H-Y antiserum and complement obtained from the guinea pig. The optimal condition for the activity of H-Y antibody was also investigated by culturing embryos under the concentraton or affected H-Y antibody was also investigated by culturing embryos under the concentration or affected H-Y antibody and culture rate. However, production of live young or sex rates of male and female from embryos transferred with psudopregnant. The biological test with the morula stage embryos showed that H-Y antibody was formed in all female rats immunized with spleen cell, but it was formed only in 80% female rats immunized with the antigen. When the bisected mouse embryos were cultured in vitro for 5~6 hours in morula stage, of 457 bisected embryos 81.4% of then were developed to the blastocyst stage. When the concentration rate of complement to H-Y antiserum varied from 1.0~5.0${mu}ell$, the lysis-rate of embryo was 19.5 to 67.3%. The concentration rate of complement did not influence the lysis-rate of embryos(P<0.05). The morphology embryos of bisected, zona-free and intact embryos showed the embryos lysis rate of 58.6, 42.7 and 48.5% respectively(P<0.05). Pregnancy rate were 50.0, 45.5 and 57.1% in psudopregnant recipient transferred with bisected, zona-free and intact blastocyst embryos. However, production of live youngs, sexual rate of male or female was 24(50.0:50.0), 22(45.5:55.5) and 36(58.3:41.7)mice, but affected and non affected half embryos with H-Y antiserum treatment was 23.1 and 26.7%. Also production of live youngs and sexual rate was 14(92.9:7.1) and 17(17.6:82.4)mice in affected and non affected half embryos in H-Y antiserum treatment(P<0.05).

• IMMUNE NETWORK
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• 제12권6호
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• pp.240-246
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• 2012

Natural killer (NK) cells play a pivotal role in early surveillance against virus infection and cellular transformation, and are also implicated in the control of inflammatory response through their effector functions of direct lysis of target cells and cytokine secretion. NK cell activation toward target cell is determined by the net balance of signals transmitted from diverse activating and inhibitory receptors. A distinct feature of NK cell activation is that stimulation of resting NK cells with single activating receptor on its own cannot mount natural cytotoxicity. Instead, specific pairs of co-activation receptors are required to unleash NK cell activation via synergy- dependent mechanism. Because each co-activation receptor uses distinct signaling modules, NK cell synergy relies on the integration of such disparate signals. This explains why the study of the mechanism underlying NK cell synergy is important and necessary. Recent studies revealed that NK cell synergy depends on the integration of complementary signals converged at a critical checkpoint element but not on simple amplification of the individual signaling to overcome intrinsic activation threshold. This review focuses on the signaling events during NK cells activation and recent advances in the study of NK cell synergy.

• Parasites, Hosts and Diseases
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• 제60권3호
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• pp.155-161
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• 2022

All living organisms are destined to die. Cells, the core of those living creatures, move toward the irresistible direction of death. The question of how to die is critical and is very interesting. There are various types of death in life, including natural death, accidental death, questionable death, suicide, and homicide. The mechanisms and molecules involved in cell death also differ depending on the type of death. The dysenteric amoeba, E. histolytica, designated by the German zoologist Fritz Schaudinn in 1903, has the meaning of tissue lysis; i.e., tissue destroying, in its name. It was initially thought that the amoebae lyse tissue very quickly leading to cell death called necrosis. However, advances in measuring cell death have allowed us to more clearly investigate the various forms of cell death induced by amoeba. Increasing evidence has shown that E. histolytica can cause host cell death through induction of various intracellular signaling pathways. Understanding of the mechanisms and signaling molecules involved in host cell death induced by amoeba can provide new insights on the tissue pathology and parasitism in human amoebiasis. In this review, we emphasized on the signaling role of NADPH oxidases in reactive oxygen species (ROS)-dependent cell death by pathogenic E. histolytica.

• 한국식품과학회지
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• 제11권4호
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• pp.242-248
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• 1979

Arthrobacter luteus로부터 분리(分離)한 zymolyase 조효소(粗酵素) 표품(標品)의 효모(酵母) 세포벽(細胞壁)에 대한 용해(溶解) 활성(活性)을 측정(測定)함에 있어서, 보다 적합(適合)한 조건(條件)을 찾기 위하여, 맥아즙(麥芽汁) 배지(培地)에서, 진탕 배양(培養)한 S. sake의 용해(溶解)에 관여(關與)하는 제(諸) 인자(因子)의 영향(影響)을 검사(檢射)하였다. 1. 본(本) 용해(溶解) 효소(酵素)에 대한 S. sake 생세포(生細胞)의 용해(溶解) 감수성(感受性)은 대수(對數) 증식기(增殖期)의 세포(細胞)는 높았고, 지체기 및 정상기(定常期)의 세포(細胞)는 낮았다. 그 중에서 특(特)히 18시간(時間) 배양(培養)된 세포(細胞)는 가장 높은 용해(溶解) 감수성(感受性)을 보였다. 2. 본(本) 용해(溶解) 효소(酵素)는 S. sake의 생세포(生細胞)에 대해서 아주 낮은 용해(溶解) 활성(活性)을 나타냈으나, 효모(酵母) 세포(細胞)를 아유산(亞硫酸) 소-다(0.05 M)로 전처리(前處理)하므로서 그 용해(溶解) 활성(活性)은 4배(倍) 이상(以上)으로 증가(增加)되었다. 3. 시중(市中)의 빵 효모(酵母)에 대해 본(本 ) 용해(溶解) 효소(酵素)의 활성(活性)은 지급히 미약(微弱)하였고 아유산(亞硫酸) 소다의 효과(效果)도 약하였다. 4. 동결(凍結) 건조(乾燥)시킨 빵 효모(酵母)의 세포(細胞)는 생세포(生細胞)의 경우 보다 높은 용해(溶解) 감수성(感受性)을 보였다. 그러나 동결(凍結) 건조(乾燥) 세포(細胞)의 경우, S. sake나 빵 효모(酵母)의 그 어느 세포(細胞)도 아유산(亞硫酸) 소-다에 의한 용해(溶解) 감수성(感受性)의 영향(影響)은 인정(認定)되지 않았다. 5. 효모(酵母) 세포벽(細胞壁) 용해(溶解)에 있어서, 그 반응(反應) 속도(速度)와 조효소(粗酵素)의 농도(濃度)와의 관계(關係)는 효소(酵素) 반응(反應) 속도론(速度論)에 준(準)하는 경향(傾向)을 보이는 것 같았으나, 반응(反應) 속도(速度)와 효모(酵母) 세포(細胞)의 농도(濃度)와의 관계(關係)는 효소(酵素) 반응(反應) 속도론(速度論)과는 다른 패턴을 보여주었다. 6. 0.05 M phoshate buffer (pH 7.5)에 용해(溶解)시킨 zymolyase 조세포(粗細胞) 표품(標品)을 $7^{\circ}C$에서 10일간(日間) 보존(保存) 시킨 결과(結果), 용해(溶解) 활성(活性)의 잔존(殘存)율은 약(約) 80 %였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVI)
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• pp.564-564
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• 2005

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.2321-2322
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• 2008

무선 유도 가열기(wireless induction heating system)를 바이오칩에서 사용 될 세포 파괴 기술을 이용하였다. 자기장에 의해 발생하는 유도전류를 열원으로 이용한 것으로 교류자기장에 금속을 놓아두면 전자기 유도 현상에 의해 금속에 와전류(eddy current)가 발생하고 발생된 전류(AC)에 의해 금속이 가열된다. 이 전류는 순간적으로 강한 열을 발생시켜 바이오칩 내에서 이를 이용해 짧은 시간동안에 효과적으로 세포를 파괴하였다.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1997년도 학술발표회
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• pp.34-34
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• 1997

Vibrio vulnificus is an estuarine bacterium that has been associated with septicemia and serious wound infection in person. Cytolysin has been incriminated as one of the important virulence determinants. Little is known about the target cell of Vibrio vulnificus cytolysin in the body. Recently, we observed cytolysin-induced blood coagulation in rat.(omitted)