Background Infection with Helicobacter pylori （H. pylon） may lead to chronic inflammation of the stomach epithelium, mucosal atrophy, imbalance of proliferation and apoptosis of epithelial cells; resulting in chroni...Background Infection with Helicobacter pylori （H. pylon） may lead to chronic inflammation of the stomach epithelium, mucosal atrophy, imbalance of proliferation and apoptosis of epithelial cells; resulting in chronic gastritis, peptic ulcer, gastric cancer, and many other clinical outcomes. Why and how H. pylorus leads to gastric cancer is not clear yet. Through in vitro experiments, this study evaluated the effects of broth culture filtrate protein （BCF-P） from the supernatant of liquid culture media of H. pylori on proliferation and apoptosis of immortalized human gastric epithelial cell lines （GES-1）and gastric cancer cell lines （AGS）. Methods For the study, GES-1 and AGS cell lines mix with BCF-P and epidermal growth factor （EGF）. MTT assay and flow cytometry （FCM） determined the levels of proliferation and apoptosis. Detected expression levels of cyclooxygenase-2 （COX-2） and Fas mRNA by reverse transcription （RT）-PCR. Also did analysis of the effects of BCF-P on epidermal growth factor receptor （EGFR） tyrosine kinase activity of GES-1 and AGS cells by non-radioactive enzyme-linked assay. The Student＇s t test and one-way analysis of variance （ANOVA） were used for statistical analysis. Results BCF-P inhibited proliferation of GES-1 and AGS cells in a concentration-dependent manner. The inhibition rates are respectively 68.7% in AGS and 61.4% in GES-1. With the same dose and time for inhibiting the proliferation, BCF-P failed to induce apoptosis of GES-1 and AGS cells. Effects of BCF-P reduced the expression of Fas mRNA of GES-1 and AGS cells （P 〈0.05）. This is consistent with the effects of EGF. BCF-P reduced the expression of COX-2 mRNA of AGS cells （P 〈0.05）. This is opposite to the effects of EGF （P 〈0.05）. Effects of BCF-P improved more than three times the EGFR tyrosine kinase activity of GES-1 and AGS cells. Conclusions BCF-P inhibited the proliferation of AGS and GES-1 cells in vitro, unrelated to apoptosis. Effects of BCF-P on gastric epitheli展开更多
Microtubule arrays in prothalli large-vacuolated and meristematic dividing cells of the fern Dryopteris crassirhizoma Nakai were studied using Steedman's wax, indirect immunofluorescence labelling and confocal las...Microtubule arrays in prothalli large-vacuolated and meristematic dividing cells of the fern Dryopteris crassirhizoma Nakai were studied using Steedman's wax, indirect immunofluorescence labelling and confocal laser scanning microscopy. Results showed that the use of high paraformaldehyde concentration (8%) allowed good fixation of prothallus cells, which are characterized by numerous (meristematic cells) and big (large-vacuolated cells) vacuoles. Results also plead for the efficiency of Steedman's wax embedding method in: (1) avoiding excessive use of enzyme for digesting cell wall in the process of the microtubule cytoskeleton labelling, (2) minimizing the autofluorescence effect in cells through utilization of alcohol in sample dehydration, and (3) permitting a clear visualization of microtubule patterns during the cell mitosis. Steedman's wax, coupled with immunofluorescence labelling and confocal laser scanning microscopy techniques, allows a good investigation of cell division process in plants by using simple multicellular organisms such as fern prothalli.展开更多
The most striking morphological feature of eukaryotic cells is the presence of various membrane-enclosed compartments. These compartments, including organelles and transient transport intermediates, are not static. Ra...The most striking morphological feature of eukaryotic cells is the presence of various membrane-enclosed compartments. These compartments, including organelles and transient transport intermediates, are not static. Rather, dynamic exchange of proteins and membrane is needed to maintain cellular homeostasis. One of the most dramatic examples of membrane mobilization is seen during the process ofmacroautophagy. Macroautophagy is the primary cellular pathway for degradation of long-lived proteins and organelles. In response to environmental cues, such as starvation or other types of stress, the cell produces a unique membrane structure, the phagophore. The phagophore sequesters cytoplasm as it forms a double-membrane cytosolic vesicle, an autophagosome. Upon completion, the autophagosome fuses with a lysosome or a vacuole in yeast, which delivers hydrolases that break down the inner autophagosome membrane along with its cargo, and the resulting macromolecules are released back into the cytosol for reuse. Autophagy is therefore a recycling process, allowing cells to survive periods of nutrient limitation; however, it has a wider physiological role, participating in development and aging, and also in protection against pathogen invasion, cancer and certain neurodegenerative diseases. In many cases, the role ofautophagy is identified through studies of an autophagy-related protein, Atg6/Beclin 1. This protein is part of a lipid kinase complex, and recent studies suggest that it plays a central role in coordinating the cytoprotective function ofautophagy and in opposing the cellular death process of apoptosis. Here, we summarize our current knowledge ofAtg6/Beclin 1 in different model organisms and its unique function in the cell.展开更多
H py/ori is probably the most prevalent human pathogen worldwide. Since it was initially suggested in 1983 by Marshall and Warren to be implicated in gastritis and peptic ulcer disease, H pylori has also been implicat...H py/ori is probably the most prevalent human pathogen worldwide. Since it was initially suggested in 1983 by Marshall and Warren to be implicated in gastritis and peptic ulcer disease, H pylori has also been implicated in gastric carcinoma and was classified as a class I carcinogen. In the last two decades, a noteworthy body of research has revealed the multiple processes that this gram negative bacterium activates to cause gastroduodenal disease in humans. Most infections are acquired early in life and may persist for the life of the individual. While infected individuals mount an inflammatory response that becomes chronic, along with a detectable adaptive immune response, these responses are ineffective in clearing the infection. Hpylori has unique features that allow it to reside within the harsh conditions of the gastric environment, and also to evade the host immune response. In this review, we discuss the various virulence factors expressed by this bacterium and how they interact with the host epithelium to influence pathogenesis.展开更多
文摘Background Infection with Helicobacter pylori （H. pylon） may lead to chronic inflammation of the stomach epithelium, mucosal atrophy, imbalance of proliferation and apoptosis of epithelial cells; resulting in chronic gastritis, peptic ulcer, gastric cancer, and many other clinical outcomes. Why and how H. pylorus leads to gastric cancer is not clear yet. Through in vitro experiments, this study evaluated the effects of broth culture filtrate protein （BCF-P） from the supernatant of liquid culture media of H. pylori on proliferation and apoptosis of immortalized human gastric epithelial cell lines （GES-1）and gastric cancer cell lines （AGS）. Methods For the study, GES-1 and AGS cell lines mix with BCF-P and epidermal growth factor （EGF）. MTT assay and flow cytometry （FCM） determined the levels of proliferation and apoptosis. Detected expression levels of cyclooxygenase-2 （COX-2） and Fas mRNA by reverse transcription （RT）-PCR. Also did analysis of the effects of BCF-P on epidermal growth factor receptor （EGFR） tyrosine kinase activity of GES-1 and AGS cells by non-radioactive enzyme-linked assay. The Student＇s t test and one-way analysis of variance （ANOVA） were used for statistical analysis. Results BCF-P inhibited proliferation of GES-1 and AGS cells in a concentration-dependent manner. The inhibition rates are respectively 68.7% in AGS and 61.4% in GES-1. With the same dose and time for inhibiting the proliferation, BCF-P failed to induce apoptosis of GES-1 and AGS cells. Effects of BCF-P reduced the expression of Fas mRNA of GES-1 and AGS cells （P 〈0.05）. This is consistent with the effects of EGF. BCF-P reduced the expression of COX-2 mRNA of AGS cells （P 〈0.05）. This is opposite to the effects of EGF （P 〈0.05）. Effects of BCF-P improved more than three times the EGFR tyrosine kinase activity of GES-1 and AGS cells. Conclusions BCF-P inhibited the proliferation of AGS and GES-1 cells in vitro, unrelated to apoptosis. Effects of BCF-P on gastric epitheli
文摘Microtubule arrays in prothalli large-vacuolated and meristematic dividing cells of the fern Dryopteris crassirhizoma Nakai were studied using Steedman's wax, indirect immunofluorescence labelling and confocal laser scanning microscopy. Results showed that the use of high paraformaldehyde concentration (8%) allowed good fixation of prothallus cells, which are characterized by numerous (meristematic cells) and big (large-vacuolated cells) vacuoles. Results also plead for the efficiency of Steedman's wax embedding method in: (1) avoiding excessive use of enzyme for digesting cell wall in the process of the microtubule cytoskeleton labelling, (2) minimizing the autofluorescence effect in cells through utilization of alcohol in sample dehydration, and (3) permitting a clear visualization of microtubule patterns during the cell mitosis. Steedman's wax, coupled with immunofluorescence labelling and confocal laser scanning microscopy techniques, allows a good investigation of cell division process in plants by using simple multicellular organisms such as fern prothalli.
文摘The most striking morphological feature of eukaryotic cells is the presence of various membrane-enclosed compartments. These compartments, including organelles and transient transport intermediates, are not static. Rather, dynamic exchange of proteins and membrane is needed to maintain cellular homeostasis. One of the most dramatic examples of membrane mobilization is seen during the process ofmacroautophagy. Macroautophagy is the primary cellular pathway for degradation of long-lived proteins and organelles. In response to environmental cues, such as starvation or other types of stress, the cell produces a unique membrane structure, the phagophore. The phagophore sequesters cytoplasm as it forms a double-membrane cytosolic vesicle, an autophagosome. Upon completion, the autophagosome fuses with a lysosome or a vacuole in yeast, which delivers hydrolases that break down the inner autophagosome membrane along with its cargo, and the resulting macromolecules are released back into the cytosol for reuse. Autophagy is therefore a recycling process, allowing cells to survive periods of nutrient limitation; however, it has a wider physiological role, participating in development and aging, and also in protection against pathogen invasion, cancer and certain neurodegenerative diseases. In many cases, the role ofautophagy is identified through studies of an autophagy-related protein, Atg6/Beclin 1. This protein is part of a lipid kinase complex, and recent studies suggest that it plays a central role in coordinating the cytoprotective function ofautophagy and in opposing the cellular death process of apoptosis. Here, we summarize our current knowledge ofAtg6/Beclin 1 in different model organisms and its unique function in the cell.
基金the National Institutes of Health Grants DK50669and DK56338 EB was a recipient of a fellowship under NationaInstitutes of Health T32 AI007536-06 Training Grant. The costs ofpublication of this article were defrayed in part by the payment ofpage charges. The article must therefore be marked advertisemenin accordance with 18 U.S.C. section 1734 solely to indicate thisfact
文摘H py/ori is probably the most prevalent human pathogen worldwide. Since it was initially suggested in 1983 by Marshall and Warren to be implicated in gastritis and peptic ulcer disease, H pylori has also been implicated in gastric carcinoma and was classified as a class I carcinogen. In the last two decades, a noteworthy body of research has revealed the multiple processes that this gram negative bacterium activates to cause gastroduodenal disease in humans. Most infections are acquired early in life and may persist for the life of the individual. While infected individuals mount an inflammatory response that becomes chronic, along with a detectable adaptive immune response, these responses are ineffective in clearing the infection. Hpylori has unique features that allow it to reside within the harsh conditions of the gastric environment, and also to evade the host immune response. In this review, we discuss the various virulence factors expressed by this bacterium and how they interact with the host epithelium to influence pathogenesis.
