Characterization of an aqueous extract of human placenta, used as a licensed drug for wound healing, leads to the identification of several bioactive components including polydeoxyribonu-cleotides (PDRNs). PDRNs are m...Characterization of an aqueous extract of human placenta, used as a licensed drug for wound healing, leads to the identification of several bioactive components including polydeoxyribonu-cleotides (PDRNs). PDRNs are mixture of DNA fragments of different molecular weight. A spectro-fluorimetric method of quantitation of PDRNs in the aqueous extract of human placenta by using ethidium bromide (EtBr) has been described here. It has been demonstrated by thin layer chromatography (TLC) followed by reversed phase HPLC that EtBr binds specifically with the PDRN fraction of the multi-component extract. The binding specificity of EtBr has been verified by the analysis of emission spectra of the extract. A concentration of 0.29 μg/ml EtBr exhibits a linear range of standard CT-DNA from 0.5 - 5 μg/ml of buffer (R2 = 0.992). The same concentration of EtBr shows a linear range of measurements of placenta extract from 5 - 35 μl/ml of buffer (R2 = 0.976). The points of the curve were the average of three sets where maximum variation observed was ±3%. PDRN content of the extract has been estimated based on the resultant fluorescence emission (after background correction) with respect to the standard calibration curve of calf thymus DNA (CT-DNA). Estimation of PDRN in a large number of batches of placenta extract (n = 100) has been done. The statistical analysis of the estimation was found to be significant and the lower and upper levels of PDRN were 158.30 and 239.03 μg/ml of the extract respectively. This easy-to-use method of estimation of PDRN in multi-component biological extract is reported for the first time. This will help in quantitation of PDRNs for other biological extracts.展开更多
Ethidium bromide(EtBr)is one of the contaminants recorded in aquatic environments whose effects have been investigated;however,there is still limited knowledge about its remediation.This study examined the potential p...Ethidium bromide(EtBr)is one of the contaminants recorded in aquatic environments whose effects have been investigated;however,there is still limited knowledge about its remediation.This study examined the potential protective effects of Spirulina platensis(SP)against the effects of EtBr toxicity in the Nile tilapia(Oreochromis niloticus)fry.Fry were divided to five groups,viz.,a control and four treatment groups of low-dose EtBr(10μg/L),low-dose EtBr with SP(10μg/L EtBr+200 mg/L SP),high-dose EtBr(100μg/L),and high-dose EtBr with SP(100μg/L EtBr+200 mg/L SP);the exposure period was 2 weeks.Low and high doses of EtBr induced alterations in some hematological,biochemical,and histopathological parameters.Necrotic hepatocytes,degenerated area,vacuolated hepatocytes,pyknotic nuclei,constricted and dilated blood sinusoids,and infiltration of inflammatory cells were observed.Lipid peroxidation concentration was not significantly different in groups exposed to low doses of EtBr and EtBr with SP,but it was increased in groups exposed to high doses of EtBr and EtBr with SP,compared with the control group.After feeding with SP,most histological and histochemical parameters restored to normal values.Therefore,SP may possess the ability to preserve the structural integrity of the hepatic and renal membranes.展开更多
Since the discovery of anticancer efficacy of titanocene dichloride （Cp<sub>2</sub>TiCl<sub>2</sub>, TDC） by Koepf in 1979, the study of antitumor properties of metallocene complexes is one o...Since the discovery of anticancer efficacy of titanocene dichloride （Cp<sub>2</sub>TiCl<sub>2</sub>, TDC） by Koepf in 1979, the study of antitumor properties of metallocene complexes is one of the most active subjects after that of cisplatin in this field. Being highly active against展开更多
Three-dimensional fluorescence (TDF) spectra of ethidium bromide (EB) in various environments, such as different types of micelle and glycerol solution, have recentiy been studied. In this note, the TDF spectra of EB ...Three-dimensional fluorescence (TDF) spectra of ethidium bromide (EB) in various environments, such as different types of micelle and glycerol solution, have recentiy been studied. In this note, the TDF spectra of EB are used to study the conformation change of calf thymus (CT) DNA and fish sperm (FS) DNA in different conditions.The results show that the TDF spectra of EB can not only be used to fingerprint CT DNA and FS DNA, but also effectively explain the interaction between EB and DNA and indicate the conformation change of DNA in different conditions.展开更多
Under different conditions, oligonucleotides can form several alternative DNA structures such as duplex, triplex and quadruplex. All these structures can interact with ethidium bromide (EB) and make its fluorescence i...Under different conditions, oligonucleotides can form several alternative DNA structures such as duplex, triplex and quadruplex. All these structures can interact with ethidium bromide (EB) and make its fluorescence intensity change. The fluorescence spectra and other related parameters provided by static fluorescence techniques showed that the interaction mechanisms between EB and these structures were not always the same. Among them, B type duplex and triplex DNA adopt an intercalative mode when binding to the EB, which has a relatively high efficiency of energy transfer and the fluorescence of EB cannot be quenched easily. While for the parallel duplex DNA, the interaction mode is an outside binding in which energy transfer can hardly happen and its fluorescence intensity as well as Stern-Volmer constant is almost the same to the free EB. For the quadruplex, the binding mechanism to EB is more complex. Results from the energy transfer and quenching studies indicate that the two interaction modes noted above probably coexist at the same time.展开更多
The preparations,the formation conditions and stabilities of duplex dA_(10)·dT_(10)and triplax dA_(10)·2dT_(10),and the interactions of ethidium bromide with them in an appropriate buffer are reported.Flu- o...The preparations,the formation conditions and stabilities of duplex dA_(10)·dT_(10)and triplax dA_(10)·2dT_(10),and the interactions of ethidium bromide with them in an appropriate buffer are reported.Flu- orescence spectra show that ethidium can be used as a useful fluorescence probe to detect triplex formation, and its fluorescence is significantly increased by either the duplex or triplex,but less in the case of the triplex.Thermal denaturation profiles demonstrate that the stability of the triplex is enhanced by ethidium. Fluorescence energy transfer studies suggest the existence of similar energy transfer from the triplex or du- plex to the bound ethidium but the presence of the triplex results in substantially smaller energy transfer than that of the duplex does.Furthermore,fluorescence quenching using the anionic quencher[Fe(CN)_6]^(4-)can- not decrease the fluorescence intensities of triplex/ethidium complex.These results demonstrate that ethidi- um has significantly binding affinity with the triplex,and interacts with it via intercalative mechanism,thus increases its stability.展开更多
文摘Characterization of an aqueous extract of human placenta, used as a licensed drug for wound healing, leads to the identification of several bioactive components including polydeoxyribonu-cleotides (PDRNs). PDRNs are mixture of DNA fragments of different molecular weight. A spectro-fluorimetric method of quantitation of PDRNs in the aqueous extract of human placenta by using ethidium bromide (EtBr) has been described here. It has been demonstrated by thin layer chromatography (TLC) followed by reversed phase HPLC that EtBr binds specifically with the PDRN fraction of the multi-component extract. The binding specificity of EtBr has been verified by the analysis of emission spectra of the extract. A concentration of 0.29 μg/ml EtBr exhibits a linear range of standard CT-DNA from 0.5 - 5 μg/ml of buffer (R2 = 0.992). The same concentration of EtBr shows a linear range of measurements of placenta extract from 5 - 35 μl/ml of buffer (R2 = 0.976). The points of the curve were the average of three sets where maximum variation observed was ±3%. PDRN content of the extract has been estimated based on the resultant fluorescence emission (after background correction) with respect to the standard calibration curve of calf thymus DNA (CT-DNA). Estimation of PDRN in a large number of batches of placenta extract (n = 100) has been done. The statistical analysis of the estimation was found to be significant and the lower and upper levels of PDRN were 158.30 and 239.03 μg/ml of the extract respectively. This easy-to-use method of estimation of PDRN in multi-component biological extract is reported for the first time. This will help in quantitation of PDRNs for other biological extracts.
文摘Ethidium bromide(EtBr)is one of the contaminants recorded in aquatic environments whose effects have been investigated;however,there is still limited knowledge about its remediation.This study examined the potential protective effects of Spirulina platensis(SP)against the effects of EtBr toxicity in the Nile tilapia(Oreochromis niloticus)fry.Fry were divided to five groups,viz.,a control and four treatment groups of low-dose EtBr(10μg/L),low-dose EtBr with SP(10μg/L EtBr+200 mg/L SP),high-dose EtBr(100μg/L),and high-dose EtBr with SP(100μg/L EtBr+200 mg/L SP);the exposure period was 2 weeks.Low and high doses of EtBr induced alterations in some hematological,biochemical,and histopathological parameters.Necrotic hepatocytes,degenerated area,vacuolated hepatocytes,pyknotic nuclei,constricted and dilated blood sinusoids,and infiltration of inflammatory cells were observed.Lipid peroxidation concentration was not significantly different in groups exposed to low doses of EtBr and EtBr with SP,but it was increased in groups exposed to high doses of EtBr and EtBr with SP,compared with the control group.After feeding with SP,most histological and histochemical parameters restored to normal values.Therefore,SP may possess the ability to preserve the structural integrity of the hepatic and renal membranes.
基金Project supported by the National Natural Science Foundation of Chinaby the Youth Science Foundation of Shanxi Province.
文摘Since the discovery of anticancer efficacy of titanocene dichloride （Cp<sub>2</sub>TiCl<sub>2</sub>, TDC） by Koepf in 1979, the study of antitumor properties of metallocene complexes is one of the most active subjects after that of cisplatin in this field. Being highly active against
基金Project supported by the National Natural Science Foundation of China.
文摘Three-dimensional fluorescence (TDF) spectra of ethidium bromide (EB) in various environments, such as different types of micelle and glycerol solution, have recentiy been studied. In this note, the TDF spectra of EB are used to study the conformation change of calf thymus (CT) DNA and fish sperm (FS) DNA in different conditions.The results show that the TDF spectra of EB can not only be used to fingerprint CT DNA and FS DNA, but also effectively explain the interaction between EB and DNA and indicate the conformation change of DNA in different conditions.
基金Project supported by the Ninth Five-Year Plan Key Project Grant of the Chinese Academy of Sciences
文摘Under different conditions, oligonucleotides can form several alternative DNA structures such as duplex, triplex and quadruplex. All these structures can interact with ethidium bromide (EB) and make its fluorescence intensity change. The fluorescence spectra and other related parameters provided by static fluorescence techniques showed that the interaction mechanisms between EB and these structures were not always the same. Among them, B type duplex and triplex DNA adopt an intercalative mode when binding to the EB, which has a relatively high efficiency of energy transfer and the fluorescence of EB cannot be quenched easily. While for the parallel duplex DNA, the interaction mode is an outside binding in which energy transfer can hardly happen and its fluorescence intensity as well as Stern-Volmer constant is almost the same to the free EB. For the quadruplex, the binding mechanism to EB is more complex. Results from the energy transfer and quenching studies indicate that the two interaction modes noted above probably coexist at the same time.
基金the Eighth Five-Year Plan's Key Basic Research Project of Academia Sinica
文摘The preparations,the formation conditions and stabilities of duplex dA_(10)·dT_(10)and triplax dA_(10)·2dT_(10),and the interactions of ethidium bromide with them in an appropriate buffer are reported.Flu- orescence spectra show that ethidium can be used as a useful fluorescence probe to detect triplex formation, and its fluorescence is significantly increased by either the duplex or triplex,but less in the case of the triplex.Thermal denaturation profiles demonstrate that the stability of the triplex is enhanced by ethidium. Fluorescence energy transfer studies suggest the existence of similar energy transfer from the triplex or du- plex to the bound ethidium but the presence of the triplex results in substantially smaller energy transfer than that of the duplex does.Furthermore,fluorescence quenching using the anionic quencher[Fe(CN)_6]^(4-)can- not decrease the fluorescence intensities of triplex/ethidium complex.These results demonstrate that ethidi- um has significantly binding affinity with the triplex,and interacts with it via intercalative mechanism,thus increases its stability.
