In any multi-cellular organism, the balance between cell division and cell death maintains a constant cell number. Both cell division cycle and cell death are highly regulated events. Whether the cell will proceed thr...In any multi-cellular organism, the balance between cell division and cell death maintains a constant cell number. Both cell division cycle and cell death are highly regulated events. Whether the cell will proceed through the cycle or not, depends upon whether the conditions required at the checkpoints during the cycle are fulfilled. In higher eucaryotic cells, such as mammalian cells, signals that arrest the cycle usually act at a G1 checkpoint. Cells that pass this restriction point are committed to complete the cycle. Regulation of the GI phase of the cell cycle is extremely complex and involves many different families of proteins such as retinoblastoma family cyclin dependent kinases, cyclins, and cyclic kinase inhibitors.展开更多
Upon encountering the antigen (Ag), the immune system can either develop a specific immune response or enter a specific state of unresponsiveness, tolerance. The response of B cells to their specific Ag can be activat...Upon encountering the antigen (Ag), the immune system can either develop a specific immune response or enter a specific state of unresponsiveness, tolerance. The response of B cells to their specific Ag can be activation and proliferation, leading to the immune response, or anergy and activation-induced cell death (AICD), leading to tolerance. AICD in B lymphocytes is a highly regulated event initiated by crosslinking of the B cell receptor (BCR). BCR engagement initiates several signaling events such as activation of PLCr, Ras, and PI3K, which generally speaking, lead to survival. However, in the absence of survival signals (CD40 or IL-4R engagement), BCR crosslinking can also promote apoptotic signal transduction pathways such as activation of effector caspases, expression of pro-apoptotic genes, and inhibition of pro-survival genes. The complex interplay between survival and death signals determines the B cell fate and, consequently, the immune response.展开更多
IL-4 is an important B cell survival and growth factor. IL-4 induced the tyrosine phosphorylation of IRS2 in resting B lymphocytes and in LPS- or CD40L-activated blasts. Phosphorylated IRS2 coprecipitated with the p85...IL-4 is an important B cell survival and growth factor. IL-4 induced the tyrosine phosphorylation of IRS2 in resting B lymphocytes and in LPS- or CD40L-activated blasts. Phosphorylated IRS2 coprecipitated with the p85 subunit of PI 3’ kinase in both resting and activated cells. By contrast, association of phosphorylated IRS2 with GRB2 was not detected in resting B cells after IL-4 treatment although both proteins were expressed. However, IL-4 induced association of IRS2 with GRB2 in B cell blasts. The pattern of IL-4- induced recruitment of p85 and GRB2 to IRS2 observed in B cells derived from STAT6 null mice was identical to that observed for normal mice. While IL-4 alone does not induce activation of MEK, a MEKI inhibitor suppressed the IL-4-induced proliferative response of LPS-activated B cell blasts. These results demonstrate that costimulation of splenic B cells alters IL-4-induced signal transduction independent of STAT6 leading to proliferation. Furthermore, proliferation induced by IL-4 in LPS-activated blasts is dependent upon the MAP kinase pathway.展开更多
Neutrophils are the first cell type to arrive at the in-jury sites and play a critical role in host defense, by virtueof its ability to adhere and transmigrate through endothe-lium, to phagocytose foreign pathogens, a...Neutrophils are the first cell type to arrive at the in-jury sites and play a critical role in host defense, by virtueof its ability to adhere and transmigrate through endothe-lium, to phagocytose foreign pathogens, and to producefree oxygen radicals and proteolytic enzymes. Yet, inap-propriate neutrophil activation causes tissue damage andvarious inflammatory diseases. These physiological andpathological functions of neutrophils depend on the en-gagement of certain surface receptors, especially αMβ2,the ma jor β2 integrin receptor present on neutrophil sur-face. Understanding of the molecular mechanisms under-lying ligand binding by αMβ2, as well as the roles of αMβ2-ligand interactions in neutrophil functions will enable usto regulate more precisely neutrophil activities: that is,to promote their host defense functions, and at the sametime to minimize their deleterious effects on normal cells.展开更多
2017年的“设计业奥斯卡”总其颁发了102件“至尊奖”（Best of the Best），其中让人感到惊喜的是：中国设计就占了10％！这是红点奖成立六十多年来的首例，也正式开启了后制造的中国设计新时代。环看这些至尊奖设计，尤其在包罗万象...2017年的“设计业奥斯卡”总其颁发了102件“至尊奖”（Best of the Best），其中让人感到惊喜的是：中国设计就占了10％！这是红点奖成立六十多年来的首例，也正式开启了后制造的中国设计新时代。环看这些至尊奖设计，尤其在包罗万象的奖项类别中（单单是参选产品总数就超过5500件）就能窥探出中国设计的功力和潜力所在：不管是已获奖无数的家电和大众消费品类、逐渐站稳脚步的家居用品类或是引领群雄的机器人领域，皆延续了去年充满科技和未来性的获奖趋势。展开更多
Four enzyme immunoassay (EIA) test kits, 1 Canadian product and 3 Chinese products,were used in the comparative study. Each pool consisted of 5 sera, and the 5 single sera were tested as controls. The tests were carri...Four enzyme immunoassay (EIA) test kits, 1 Canadian product and 3 Chinese products,were used in the comparative study. Each pool consisted of 5 sera, and the 5 single sera were tested as controls. The tests were carried out according to the instructions, keeping the same dilution of each serum in single and pool samples. It was found that with the Canadian kit,the positive and negative results of opled sera had no difference from that of the controls (P>0. 10). In the case of Chinese Yali and Kehua kits, the positive results of pooled sera showed no difference from the controls (P >0. 10), but the optical density (OD) of negative opls were increased (P < 0. 01 ), though quite distant from the cut-off values. In the case of Changzheng kit, the OD of opitive opls were significantly lower than those of the controls (P < 0. 05 ), and weak positive samples missed the detection. However this problem could be overcome by blocking the microwells beforehand. Our experiment demonstrate that not all EIA test kits are suitable for screening opls for antithey to hepatitis C virus, and that it is important to assess the sensitivity of the EIA kit to be used for this purpose.展开更多
Since their discovery over 100 years ago, sphingolipids have caught the eyes and the imagination of scientists.Modern science has made many new insights on the cell biology and day-to-day functions of many integral sp...Since their discovery over 100 years ago, sphingolipids have caught the eyes and the imagination of scientists.Modern science has made many new insights on the cell biology and day-to-day functions of many integral sphingolipids, especially those of ceramide. Ceramide is recognized as a vital second messenger in the signal transduction process mediated by receptors of many cytokines and growth factors.A great part of our current understanding of ceramide has been achieved from apoptosis-related studies, however recent data in the fields of immunology, endocrinology and neurobiology, also suggest a fundamental involvement of ceramide in the onset of diseases. Therefore, understanding the biology of ceramide could be a key to unraveling many biological mechanisms and provide information for the treatment of some common diseases.展开更多
文摘In any multi-cellular organism, the balance between cell division and cell death maintains a constant cell number. Both cell division cycle and cell death are highly regulated events. Whether the cell will proceed through the cycle or not, depends upon whether the conditions required at the checkpoints during the cycle are fulfilled. In higher eucaryotic cells, such as mammalian cells, signals that arrest the cycle usually act at a G1 checkpoint. Cells that pass this restriction point are committed to complete the cycle. Regulation of the GI phase of the cell cycle is extremely complex and involves many different families of proteins such as retinoblastoma family cyclin dependent kinases, cyclins, and cyclic kinase inhibitors.
文摘Upon encountering the antigen (Ag), the immune system can either develop a specific immune response or enter a specific state of unresponsiveness, tolerance. The response of B cells to their specific Ag can be activation and proliferation, leading to the immune response, or anergy and activation-induced cell death (AICD), leading to tolerance. AICD in B lymphocytes is a highly regulated event initiated by crosslinking of the B cell receptor (BCR). BCR engagement initiates several signaling events such as activation of PLCr, Ras, and PI3K, which generally speaking, lead to survival. However, in the absence of survival signals (CD40 or IL-4R engagement), BCR crosslinking can also promote apoptotic signal transduction pathways such as activation of effector caspases, expression of pro-apoptotic genes, and inhibition of pro-survival genes. The complex interplay between survival and death signals determines the B cell fate and, consequently, the immune response.
文摘IL-4 is an important B cell survival and growth factor. IL-4 induced the tyrosine phosphorylation of IRS2 in resting B lymphocytes and in LPS- or CD40L-activated blasts. Phosphorylated IRS2 coprecipitated with the p85 subunit of PI 3’ kinase in both resting and activated cells. By contrast, association of phosphorylated IRS2 with GRB2 was not detected in resting B cells after IL-4 treatment although both proteins were expressed. However, IL-4 induced association of IRS2 with GRB2 in B cell blasts. The pattern of IL-4- induced recruitment of p85 and GRB2 to IRS2 observed in B cells derived from STAT6 null mice was identical to that observed for normal mice. While IL-4 alone does not induce activation of MEK, a MEKI inhibitor suppressed the IL-4-induced proliferative response of LPS-activated B cell blasts. These results demonstrate that costimulation of splenic B cells alters IL-4-induced signal transduction independent of STAT6 leading to proliferation. Furthermore, proliferation induced by IL-4 in LPS-activated blasts is dependent upon the MAP kinase pathway.
文摘Neutrophils are the first cell type to arrive at the in-jury sites and play a critical role in host defense, by virtueof its ability to adhere and transmigrate through endothe-lium, to phagocytose foreign pathogens, and to producefree oxygen radicals and proteolytic enzymes. Yet, inap-propriate neutrophil activation causes tissue damage andvarious inflammatory diseases. These physiological andpathological functions of neutrophils depend on the en-gagement of certain surface receptors, especially αMβ2,the ma jor β2 integrin receptor present on neutrophil sur-face. Understanding of the molecular mechanisms under-lying ligand binding by αMβ2, as well as the roles of αMβ2-ligand interactions in neutrophil functions will enable usto regulate more precisely neutrophil activities: that is,to promote their host defense functions, and at the sametime to minimize their deleterious effects on normal cells.
文摘2017年的“设计业奥斯卡”总其颁发了102件“至尊奖”（Best of the Best），其中让人感到惊喜的是：中国设计就占了10％！这是红点奖成立六十多年来的首例，也正式开启了后制造的中国设计新时代。环看这些至尊奖设计，尤其在包罗万象的奖项类别中（单单是参选产品总数就超过5500件）就能窥探出中国设计的功力和潜力所在：不管是已获奖无数的家电和大众消费品类、逐渐站稳脚步的家居用品类或是引领群雄的机器人领域，皆延续了去年充满科技和未来性的获奖趋势。
文摘Four enzyme immunoassay (EIA) test kits, 1 Canadian product and 3 Chinese products,were used in the comparative study. Each pool consisted of 5 sera, and the 5 single sera were tested as controls. The tests were carried out according to the instructions, keeping the same dilution of each serum in single and pool samples. It was found that with the Canadian kit,the positive and negative results of opled sera had no difference from that of the controls (P>0. 10). In the case of Chinese Yali and Kehua kits, the positive results of pooled sera showed no difference from the controls (P >0. 10), but the optical density (OD) of negative opls were increased (P < 0. 01 ), though quite distant from the cut-off values. In the case of Changzheng kit, the OD of opitive opls were significantly lower than those of the controls (P < 0. 05 ), and weak positive samples missed the detection. However this problem could be overcome by blocking the microwells beforehand. Our experiment demonstrate that not all EIA test kits are suitable for screening opls for antithey to hepatitis C virus, and that it is important to assess the sensitivity of the EIA kit to be used for this purpose.
文摘Since their discovery over 100 years ago, sphingolipids have caught the eyes and the imagination of scientists.Modern science has made many new insights on the cell biology and day-to-day functions of many integral sphingolipids, especially those of ceramide. Ceramide is recognized as a vital second messenger in the signal transduction process mediated by receptors of many cytokines and growth factors.A great part of our current understanding of ceramide has been achieved from apoptosis-related studies, however recent data in the fields of immunology, endocrinology and neurobiology, also suggest a fundamental involvement of ceramide in the onset of diseases. Therefore, understanding the biology of ceramide could be a key to unraveling many biological mechanisms and provide information for the treatment of some common diseases.
