The Daunomycin, Cyclophosphamide, Cytarabine Hydrochloride and Vincrlstine Sulfale all are the drugs used in the therapy of leukemia. When the leukemia cell line, K562, were treated by them in vitro, a sharp decrease ...The Daunomycin, Cyclophosphamide, Cytarabine Hydrochloride and Vincrlstine Sulfale all are the drugs used in the therapy of leukemia. When the leukemia cell line, K562, were treated by them in vitro, a sharp decrease of intracellular free Ca2+ concentration could be found. The anti-cancer mechanisms of these drugs are inhibiting the DNA or RNA syntheses and Interrupting the mitoses of tumor cells. Our experiment suggested that beside the above behaviors, these anti-cancer drugs can also suppress the function of tumor cells by means of decreasing their intracellular Ca2+ levels.展开更多
O6-methylguanine-DNA Methyltransferase (MGMT) can specifically repair the DNA demage Induced by chioroethylnitrosoureas (CENU) such at 1-(4-amino-2-methyt-pyrlmidinyl) methyl-3-(2-chloroethyl-)-3-nitrosourea (ACNU), c...O6-methylguanine-DNA Methyltransferase (MGMT) can specifically repair the DNA demage Induced by chioroethylnitrosoureas (CENU) such at 1-(4-amino-2-methyt-pyrlmidinyl) methyl-3-(2-chloroethyl-)-3-nitrosourea (ACNU), constituting the molecular basis of tumor cell resistance to CENU. The present study demonstrated that sensitization of resistant tumor cells to ACNU could be achieved by streptozotocin (STZ) treatment which could deplete MGMT activity in vitro and in vivo. It suggested that depletion of the molecular basis of tumor cell resistance to chemotherapeutic agents might be a practicable way to improve the effectiveness of tumor chemotherapy.展开更多
Some antitumor activities of component (E), extracted from the root of Fagopynum Cymosum (Trev) Meisn (FCTM), have recently been discovered in vivo and in vitro. The component E (CE)'s pattern of action with tumor...Some antitumor activities of component (E), extracted from the root of Fagopynum Cymosum (Trev) Meisn (FCTM), have recently been discovered in vivo and in vitro. The component E (CE)'s pattern of action with tumor cellular DNA at the molecular pharmacological level was investigated by macromolecular synthesis experiment (MSE) and human DNA interaction system established in our laboratory. The experiments demonstrated that, in vitro, the agent could markedly inhibit the incorporation of 3H-TdR into the cellular DNA, and the IC50 in P388 leukemia cell and in SGC-7901 cell was 17.86 μg/ml and 110.4 μg/ml, respectively. The agent, at mg/ml level, could produce an intercalation reversion pattern with DNA within a short time (2 hours). But when the interval was prolonged for over 4 hours, the action changed to intercalation irreversible pattern. According to these observations, the authors infer that CE interacts with DNA in two ways - directly and indirectly. The indirect action, especially in low concentrations, probably plays the major role. The authors have also compared the interaction of CE with those of components (CB3 and CD1), extracted from FCTM by the same methods, and found that CE is the most active agent against the DNA of cancer cells among the extracts from FCTM.展开更多
Staphylococcus aureus is a common human bacterium that sometimes becomes pathogenic,causing serious infections.A key feature of S.aureus is its ability to acquire resistance to antibiotics.The presence of the staphylo...Staphylococcus aureus is a common human bacterium that sometimes becomes pathogenic,causing serious infections.A key feature of S.aureus is its ability to acquire resistance to antibiotics.The presence of the staphylococcal cassette chromosome(SCC) element in serotypes of S.aureus has been confirmed using multiplex PCR assays.The SCC element is the only vector known to carry the mecA gene,which encodes methicillin resistance in S.aureus infections.Here,we report the genome sequence of a novel methicillin-sensitive S.aureus(MSSA) strain:SCC-like MSSA463.This strain was originally erroneously serotyped as methicillin-resistant S.aureus in a clinical laboratory using multiplex PCR methods.We sequenced the genome of SCC-like MSSA463 using pyrosequencing techniques and compared it with known genome sequences of other S.aureus isolates.An open reading frame(CZ049;AB037671) was identified downstream of attL and attR inverted repeat sequences.Our results suggest that a lateral gene transfer occurred between S.aureus and other organisms,partially changing S.aureus infectivity.We propose that attL and attR inverted repeats in S.aureus serve as frequent insertion sites for exogenous genes.展开更多
文摘The Daunomycin, Cyclophosphamide, Cytarabine Hydrochloride and Vincrlstine Sulfale all are the drugs used in the therapy of leukemia. When the leukemia cell line, K562, were treated by them in vitro, a sharp decrease of intracellular free Ca2+ concentration could be found. The anti-cancer mechanisms of these drugs are inhibiting the DNA or RNA syntheses and Interrupting the mitoses of tumor cells. Our experiment suggested that beside the above behaviors, these anti-cancer drugs can also suppress the function of tumor cells by means of decreasing their intracellular Ca2+ levels.
文摘O6-methylguanine-DNA Methyltransferase (MGMT) can specifically repair the DNA demage Induced by chioroethylnitrosoureas (CENU) such at 1-(4-amino-2-methyt-pyrlmidinyl) methyl-3-(2-chloroethyl-)-3-nitrosourea (ACNU), constituting the molecular basis of tumor cell resistance to CENU. The present study demonstrated that sensitization of resistant tumor cells to ACNU could be achieved by streptozotocin (STZ) treatment which could deplete MGMT activity in vitro and in vivo. It suggested that depletion of the molecular basis of tumor cell resistance to chemotherapeutic agents might be a practicable way to improve the effectiveness of tumor chemotherapy.
文摘Some antitumor activities of component (E), extracted from the root of Fagopynum Cymosum (Trev) Meisn (FCTM), have recently been discovered in vivo and in vitro. The component E (CE)'s pattern of action with tumor cellular DNA at the molecular pharmacological level was investigated by macromolecular synthesis experiment (MSE) and human DNA interaction system established in our laboratory. The experiments demonstrated that, in vitro, the agent could markedly inhibit the incorporation of 3H-TdR into the cellular DNA, and the IC50 in P388 leukemia cell and in SGC-7901 cell was 17.86 μg/ml and 110.4 μg/ml, respectively. The agent, at mg/ml level, could produce an intercalation reversion pattern with DNA within a short time (2 hours). But when the interval was prolonged for over 4 hours, the action changed to intercalation irreversible pattern. According to these observations, the authors infer that CE interacts with DNA in two ways - directly and indirectly. The indirect action, especially in low concentrations, probably plays the major role. The authors have also compared the interaction of CE with those of components (CB3 and CD1), extracted from FCTM by the same methods, and found that CE is the most active agent against the DNA of cancer cells among the extracts from FCTM.
基金supported by the National High Technology Research and Development Program (2006AA02Z4A9)the National Science and Technology Major Project of Ministry of Science and Technology of China (2009ZX10004,2012ZX10004206)the National Natural Science Foundation of China (30971610, 30900053)
文摘Staphylococcus aureus is a common human bacterium that sometimes becomes pathogenic,causing serious infections.A key feature of S.aureus is its ability to acquire resistance to antibiotics.The presence of the staphylococcal cassette chromosome(SCC) element in serotypes of S.aureus has been confirmed using multiplex PCR assays.The SCC element is the only vector known to carry the mecA gene,which encodes methicillin resistance in S.aureus infections.Here,we report the genome sequence of a novel methicillin-sensitive S.aureus(MSSA) strain:SCC-like MSSA463.This strain was originally erroneously serotyped as methicillin-resistant S.aureus in a clinical laboratory using multiplex PCR methods.We sequenced the genome of SCC-like MSSA463 using pyrosequencing techniques and compared it with known genome sequences of other S.aureus isolates.An open reading frame(CZ049;AB037671) was identified downstream of attL and attR inverted repeat sequences.Our results suggest that a lateral gene transfer occurred between S.aureus and other organisms,partially changing S.aureus infectivity.We propose that attL and attR inverted repeats in S.aureus serve as frequent insertion sites for exogenous genes.
