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Human Cell System (human + cell_system)

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Medical Sciences75%

Selected Abstracts

Inhibition of Human Cell Apoptosis by Silkworm Hemolymph

BIOTECHNOLOGY PROGRESS, Issue 4 2002
Shin Sik Choi
Many studies on preventing apoptosis have been carried out from the viewpoint of anti-apoptotic cloned-gene expressions inside cells, whereas in this study, we investigated the inhibition of apoptosis by the addition of silkworm hemolymph, a natural compound, from outside of the cells. In a previous study, we reported the inhibition effect of silkworm hemolymph on the baculovirus-induced insect cell apoptosis. Using the vaccinia virus-HeLa cell system as a model system in this study, we found that silkworm hemolymph, the insect serum, inhibits apoptosis not only in the insect cell system but also in the human cell system. The vaccinia virus-induced HeLa cell apoptosis was analyzed using DNA electrophoresis, TUNEL, and flow cytometry, and the resulting data confirmed that silkworm hemolymph inhibits human cell apoptosis. The inhibition of apoptosis due to silkworm hemolymph was not caused by an inhibition of virus binding and internalization steps, nor did silkworm hemolymph interfere with the virus production. The inhibition of apoptosis by silkworm hemolymph decreased the cell detachment from an adhering surface. With these characteristics, silkworm hemolymph can be effectively used to minimize cell death in commercial animal cell culture. [source]

Blockade of superoxide generation prevents high-affinity immunoglobulin E receptor-mediated release of allergic mediators by rat mast cell line and human basophils

CLINICAL & EXPERIMENTAL ALLERGY, Issue 4 2002
T. Yoshimaru
Summary Background Previous studies have shown that rat peritoneal mast cells and mast cell model rat basophilic leukaemia (RBL-2H3) cells generate intracellular reactive oxygen species (ROS) in response to antigen challenge. However, the physiological significance of the burst of ROS is poorly understood. Objective The present study was undertaken to investigate the role of superoxide anion in mediator release in rat and human cell systems. Methods RBL-2H3 cells were directly stimulated with anti-rat Fc,RI ,-subunit monoclonal antibody (mAb). For the analysis of human cell system, leucocytes were isolated by dextran sedimentation from healthy volunteers or from patients, and challenged either with anti-human Fc,RI mAb or with the relevant antigens. Superoxide generation was determined by chemiluminescence-based methods. The releases of histamine and leukotrienes (LT)s were determined by enzyme-linked immunosorben assay (ELISA). Results Cross-linking of Fc,RI on RBL-2H3 cells or on human leucocytes from healthy donors by the anti-Fc,RI mAb resulted in a rapid generation of superoxide anion, as determined by chemiluminescence using superoxide-specific probes. Similarly, leucocytes from patients generated superoxide anion in response to the challenge with the relevant allergen but not with the irrelevant allergen. Furthermore, diphenyleneiodonium (DPI), a well-known inhibitor of flavoenzymes suppressed the superoxide generation and the release of histamine and LTC4 induced by the anti-Fc,RI mAb or by allergen in parallel. Conclusion These results indicate that both RBL-2H3 cells and human basophils generate superoxide anion upon Fc,RI cross-linking either by antibody or by allergen challenge and that blockade of the generation prevents the release of allergic mediators. The findings strongly support the role of superoxide generation in the activation of mast cells and basophils under both physiological and pathological conditions. The findings suggest that drugs regulating the superoxide generation have potential therapeutic use for allergic disorders. [source]

The screening of the second-site suppressor mutations of the common p53 mutants

INTERNATIONAL JOURNAL OF CANCER, Issue 3 2007
Kazunori Otsuka
Abstract Second-site suppressor (SSS) mutations in p53 found by random mutagenesis have shown to restore the inactivated function of some tumor-derived p53. To screen novel SSS mutations against common mutant p53s, intragenic second-site (SS) mutations were introduced into mutant p53 cDNA in a comprehensive manner by using a p53 missense mutation library. The resulting mutant p53s with background and SS mutations were assayed for their ability to restore the p53 transactivation function in both yeast and human cell systems. We identified 12 novel SSS mutations including H178Y against a common mutation G245S. Surprisingly, the G245S phenotype is rescued when coexpressed with p53 bearing the H178Y mutation. This result indicated that there is a possibility that intragenic suppressor mutations might restore the protein function in an intermolecular manner. The intermolecular mechanism may lead to novel strategies for restoring inactivated p53 function and tumor suppression in cancer treatment. © 2007 Wiley-Liss, Inc. [source]

Blockade of superoxide generation prevents high-affinity immunoglobulin E receptor-mediated release of allergic mediators by rat mast cell line and human basophils

CLINICAL & EXPERIMENTAL ALLERGY, Issue 4 2002
T. Yoshimaru
Summary Background Previous studies have shown that rat peritoneal mast cells and mast cell model rat basophilic leukaemia (RBL-2H3) cells generate intracellular reactive oxygen species (ROS) in response to antigen challenge. However, the physiological significance of the burst of ROS is poorly understood. Objective The present study was undertaken to investigate the role of superoxide anion in mediator release in rat and human cell systems. Methods RBL-2H3 cells were directly stimulated with anti-rat Fc,RI ,-subunit monoclonal antibody (mAb). For the analysis of human cell system, leucocytes were isolated by dextran sedimentation from healthy volunteers or from patients, and challenged either with anti-human Fc,RI mAb or with the relevant antigens. Superoxide generation was determined by chemiluminescence-based methods. The releases of histamine and leukotrienes (LT)s were determined by enzyme-linked immunosorben assay (ELISA). Results Cross-linking of Fc,RI on RBL-2H3 cells or on human leucocytes from healthy donors by the anti-Fc,RI mAb resulted in a rapid generation of superoxide anion, as determined by chemiluminescence using superoxide-specific probes. Similarly, leucocytes from patients generated superoxide anion in response to the challenge with the relevant allergen but not with the irrelevant allergen. Furthermore, diphenyleneiodonium (DPI), a well-known inhibitor of flavoenzymes suppressed the superoxide generation and the release of histamine and LTC4 induced by the anti-Fc,RI mAb or by allergen in parallel. Conclusion These results indicate that both RBL-2H3 cells and human basophils generate superoxide anion upon Fc,RI cross-linking either by antibody or by allergen challenge and that blockade of the generation prevents the release of allergic mediators. The findings strongly support the role of superoxide generation in the activation of mast cells and basophils under both physiological and pathological conditions. The findings suggest that drugs regulating the superoxide generation have potential therapeutic use for allergic disorders. [source]