AIM:To investigate the effect of vitamin E on oxidative stress status in the small intestine of diabetic rats. METHODS:Twenty-four male Wistar rats were randomly divided into three groups:Control (C),non-treated diabe...AIM:To investigate the effect of vitamin E on oxidative stress status in the small intestine of diabetic rats. METHODS:Twenty-four male Wistar rats were randomly divided into three groups:Control (C),non-treated diabetic (NTD) and vitamin E-treated diabetic (VETD) groups. The increases in lipid peroxidation,protein oxidation and superoxide dismutase (SOD) in these three groups was compared after 6 wk. RESULTS:There was no significant difference in catalase activity between NTD and control rats. Compared to NTD rats,the treatment with vitamin E significantly decreased lipid peroxidation and protein oxidation,and also increased catalase activity and SOD. CONCLUSION:The results revealed the occurrence of oxidative stress in the small intestine of diabetic rats. Vitamin E,as an antioxidant,attenuates lipid peroxidation and protein oxidation,and increases antioxidant defense mechanism.展开更多
AIM: To investigate whether antioxidants vitamin E and C can retard development of hepatic fibrosis in the bilian/obstructed rats. METHODS: Fifty Wistar albino rats were randomly assigned to 5 groups (10 rats in e...AIM: To investigate whether antioxidants vitamin E and C can retard development of hepatic fibrosis in the bilian/obstructed rats. METHODS: Fifty Wistar albino rats were randomly assigned to 5 groups (10 rats in each). Bile duct was ligated in 40 rats and they were treated as follows: group vitC, vitamin C 10 mg/kg sc daily; group vitE, vitamin E 15 mg/kg sc daily; group vitEC, both of the vitamins; bile duct-ligated (BDL, control) group, physiological saline sc. The fifth group was assigned to sham operation. At the end of fourth week, the rats were decapitated, and hepatic tissue biochemical collagen content and collagen surface area were measured. Hepatic tissue specimens were histopathologically evaluated according to Scheuer system. Serum hyaluronate levels were measured by ELISA method. RESULTS: Despite being higher than sham group, hepatic collagen level was significantly decreased in each of the vitC, vitE and vitEC groups (32.7 ± 1.2, 33.8 ± 2.9, 36.7 ± 0.5 )μg collagen/mg protein, respectively) compared to BDL (48.3 ± 0.6 mg collagen/g protein) (P 〈 0.001 for each vitamin group). Each isolated vitamin C, isolated vitamin E and combined vitamin E/C supplementation prevented the increase in hepatic collagen surface density (7.0% ± 1.1%, 6.2% ± 1.7%, 12.3% ± 2.0%, respectively) compared to BDL (17.4% ± 5.6%) (P 〈 0.05 for each). The same beneficial effect of vitamin C, vitamin E and combined vitamin E/C treatment was also observed on the decrease of serum hyaluronate levels compared to BDL group (P 〈 0.001). The relative liver and spleen weights, serum transaminases, cholestatic enzymes, bilirubins and histopathological inflammation scores were not different between the antioxidant treatment groups and the control. However, fibrosis staging scores were obviously reduced only in the vitamin E/C combination group (vit EC: 2.4 ± 0.8 vs BDL: 3.1 ± 0.7; P 〈 0.05). CONCLUSION: Each antioxidant vitamin E, vitamin C and their combination retard hepatic fibrosis in biliary-obstructed rats. Oxidative stress may play a role in the pathogenesis of hepatic fibrosis in secondary biliary cirrhosis.展开更多
Non-a-tocopherols are hydroxymethylated and hydrogenated to produce α-tocopherol in one pot process by simultaneously reacting with paraformaldehyde and hydrogen in the presence of catalysts of benzenesulfonic acid a...Non-a-tocopherols are hydroxymethylated and hydrogenated to produce α-tocopherol in one pot process by simultaneously reacting with paraformaldehyde and hydrogen in the presence of catalysts of benzenesulfonic acid and 5% Pd/C in an autoclave. Effects of various operation conditions have been studied. The preferable reaction conditions are: temperature 180 ℃ to 200 ℃, pressure 5.0 MPa, acid concentration 0.5 g/100 ml ethanol, mass ratio of Pd/C to tocopherols 7.1 g/100 g, and reaction time 5.0 h. A product with α-tocopherol content of 80% was obtained by using a raw material with a total tocopherols content of 80.54%. The conversion of non-α-tocopherols is almost 100%, and the mole yield of a-tocopherol is more than 90%.展开更多
Tocopherol is the most active vitamin and natural antioxidant existing in the nature known as vitamin E. Lacking of this vitamin makes drastic exchanges on the health of the living organisms. Their active chemical for...Tocopherol is the most active vitamin and natural antioxidant existing in the nature known as vitamin E. Lacking of this vitamin makes drastic exchanges on the health of the living organisms. Their active chemical form is l-α-tocopherol substance. In this article, α-thiotocopherol a tocopherol derivative was synthesized via a precursor like dl-α-tocopherol, which has better antioxidant than natural α-tocopherol. And the last compound after separation and purification via TLC and PC procedures was analyzed by FTIR, GC-MS and elemental analysis, oxidative stability is tested with TGA method in air showing roughly antioxidant effect. Another approach is measurment of redox potential against a reference electrode under inert nitrogen atmosphere.展开更多
The aim of this article is to develop a structural equation model to assess key factors of residents' support for hosting mega event based on previous literature.The model consisted of five latent constructs and e...The aim of this article is to develop a structural equation model to assess key factors of residents' support for hosting mega event based on previous literature.The model consisted of five latent constructs and eight path hypotheses.A survey was conducted in Shanghai before 2010 World Expo.It was found that the support for mega events is affected directly and/or indirectly by four determinants factors:perceived benefits,perceived costs,personal benefits and community attachment,and support relies heavily on perceived benefits rather than costs.This study contributes to the existing body of knowledge in an attempt to understand local residents' support for a mega event in different economic and cultural settings.展开更多
Vitamin E succinate was synthesized in organic solvents using a modified Novozym-435 as catalyst.In order to improve the catalytic performance of Novozym-435,the enzyme was modified using acetic anhydride, propionic a...Vitamin E succinate was synthesized in organic solvents using a modified Novozym-435 as catalyst.In order to improve the catalytic performance of Novozym-435,the enzyme was modified using acetic anhydride, propionic anhydride and succinic anhydride separately.We found that both the hydrolytic activity and the thermal stability of the modified Novozym-435 were enhanced compared with the unmodified enzyme.The modified Novozym-435 catalysts were used to synthesize the succinate derivative of vitamin E.Compared with the native Novozym-435,the catalytic activity of the modified novozym-435 in promoting the synthesis of vitamin E succinate was dramatically increased,with the novozym-435 modified with succinic anhydride(N435-S)as the most active catalyst.Conditions for the synthesis of vitamin E succinate were also optimized.A mixture of tert-butanol and DMSO(volume ratio of 2︰3)was the most suitable medium for the reaction,whereas the appropriate molar ratio of vitamin E to succinic anhydride and reaction temperature were 1︰5 and 40°C,respectively.Under these reaction conditions,the yield of vitamin E succinate reached 94.4%.N435-S could be reused for five batches.展开更多
Objective: To explore the frequency and significance of ApoE gene polymorphisms in Chinese patients with atherosclerotic cerebral infarction (ACI). Methods: Polymerase chain reaction and gene sequencing, single nucleo...Objective: To explore the frequency and significance of ApoE gene polymorphisms in Chinese patients with atherosclerotic cerebral infarction (ACI). Methods: Polymerase chain reaction and gene sequencing, single nucleotide polymorphisms of ApoE gene were used to analyze 33 cases of patients with ACI and 35 controls. Results: The frequencies of ApoE gene single nucleotide polymorphisms 465C/G, 462C/G and 451delC in the ACI group were significantly higher than those in the control group (P<0.05). The prevalence of polymorphism 486G/T in the control group was significantly higher than that in the ACI group ( P = 0.011) . Conclusions: 465C/G,462C/G and 451delC polymorphisms might be associated with ACI.486GT allele might have protective effect on the pathogenesis of ACI.展开更多
Objective: We aimed to investigate protective effects ofvit E on oxidative stress status and homocysteine (Hey) in cardiac tissue of diabetic rats. Methods: Sixteen Wistar male rats were treated with STZ (strepto...Objective: We aimed to investigate protective effects ofvit E on oxidative stress status and homocysteine (Hey) in cardiac tissue of diabetic rats. Methods: Sixteen Wistar male rats were treated with STZ (streptozotocin) (60 mg/kg) to induce diabetes. Diabetic rats were divided into two groups: NTD (non-treated diabetic) and VETD (vit E-treated diabetic) rats. The VETD group received 300 mg/kg vit E with daily feeding. Eight normal rats of the same age were used as the control group. After 6 weeks, the rats were anesthetized, their cardiac tissue was removed, and homogenated supernatant was separated. Samples were assayed for TAC (total antioxidant capacity), LPO (lipid peroxidation), nitrite (NO2), nitrate (NO3), and Hcy. Key Findings: The contents of LPO, NO3 and Hcy in NTD compared to control group indicate a significant increase, but the levels of these parameters decreased in VETD (p 〈 0.05). There was a significant decrease in the amount of TAC in the NTD group but in VETD group, that significantly increased (p 〈 0.05). The amount of NO2 in NTD and VETD groups, compared to the control group, did not show any significant changes (p 〉 0.05). Conclusions: Significant decrease of oxidative stress and Hey in the cardiac tissue caused by vit E supplementation strongly indicated that this radical scavenger may promote a protective effect on diabetic cardiomyopathy through the attenuation of oxidative stress and increase antioxidant defense mechanism.展开更多
For more than two decades, immunologists have been using the so-called Th1/Th2 paradigm to explain most of the phenomena related to adaptive immunity. The Thl/Th2 paradigm implied the existence of two different, mutu-...For more than two decades, immunologists have been using the so-called Th1/Th2 paradigm to explain most of the phenomena related to adaptive immunity. The Thl/Th2 paradigm implied the existence of two different, mutu- ally regulated, CD4+ T helper subsets: Thl cells, driving cell-mediated immune responses involved in tissue damage and fighting infection against intracellular parasites; and Th2 cells that mediate IgE production and are particu- larly involved in eosinophilic inflammation, allergy and clearance of helminthic infections. A third member of the T helper set, IL-17-producing CD4+ T cells, now called Th17 cells, was recently described as a distinct lineage that does not share developmental pathways with either Thl or Th2 cells. The Th17 subset has been linked to autoimmune disorders, being able to produce IL-17, IL-17F and IL-21 among other inflammatory cytokines. Interestingly, it has been reported that there is not only a cross-regulation among Thl, Th2 and Th17 effector cells but there is also a di- chotomy in the generation of Th17 and T regulatory cells. Therefore, Treg and Th17 effector cells arise in a mutually exclusive fashion, depending on whether they are activated in the presence of TGF-β or TGF-β plus inflammatory cytokines such as IL-6. This review will address the discovery of the Th17 cells, and recent progress on their development and regulation.展开更多
In order to search for high energy density materials,various 4,8-dihydrodifurazano[3,4-b,e]pyrazine based energetic materials were designed.Density functional theory was employed to investigate the relationships betwe...In order to search for high energy density materials,various 4,8-dihydrodifurazano[3,4-b,e]pyrazine based energetic materials were designed.Density functional theory was employed to investigate the relationships between the structures and properties.The calculated results indicated that the properties of these designed compounds were influenced by the energetic groups and heterocyclic substituents.The-N3 energetic group was found to be the most effective substituent to improve the heats of formation of the designed compounds while the tetrazole ring/-C(NO_(2))_(3) group contributed much to the values of detonation properties.The analysis of bond orders and bond dissociation energies showed that the addition of-NHNH2,-NHNO_(2),-CH(NO_(2))_(3) and-C(NO_(2))_(3) groups would decrease the bond dissociation energies remarkably.Compounds A8,B8,C8,D8,E8,and F8 were finally screened as the potential candidates for high energy density materials since these compounds possess excellent detonation properties and acceptable thermal stabilities.Additionally,the electronic structures of the screened compounds were calculated.展开更多
UDP-glucose pyrophosphorylase is an important enzyme concerned with carbohydrate metabolism in plants. Cloning of UGPase is a premise for further study on molecular level, and it is also crucial for study of carbohydr...UDP-glucose pyrophosphorylase is an important enzyme concerned with carbohydrate metabolism in plants. Cloning of UGPase is a premise for further study on molecular level, and it is also crucial for study of carbohydrate metabolism. UGPase cDNA sequence as a template, designed primer, then 3'-untranslate region (3' UTR) of UGPase were amplified by 3'-rapid amplification of cDNA ends (3'-RACE). The results suggested the 3' UTR were 243 bp, contained AATAA sequence and Poly(A).展开更多
This article reviews the pathogenic mechanism of nonsteroidal anti-inflammatory drug(NSAID)-induced gastric damage,focusing on the relation between cyclooxygenase(COX) inhibition and various functional events.NSAIDs,s...This article reviews the pathogenic mechanism of nonsteroidal anti-inflammatory drug(NSAID)-induced gastric damage,focusing on the relation between cyclooxygenase(COX) inhibition and various functional events.NSAIDs,such as indomethacin,at a dose that inhibits prostaglandin(PG) production,enhance gastric motility,resulting in an increase in mucosal permeability,neutrophil infiltration and oxyradical production,and eventually producing gastric lesions.These lesions are prevented by pretreatment with PGE 2 and antisecretory drugs,and also via an atropine-sensitive mechanism,not related to antisecretory action.Although neither rofecoxib(a selective COX-2 inhibitor) nor SC-560(a selective COX-1 inhibitor) alone damages the stomach,the combined administration of these drugs provokes gastric lesions.SC-560,but not rofecoxib,decreases prostaglandin E 2(PGE 2) production and causes gastric hypermotility and an increase in mucosal permeability.COX-2 mRNA is expressed in the stomach after administration of indomethacin and SC-560 but not rofecoxib.The up-regulation of indomethacin-induced COX-2 expression is prevented by atropine at a dose that inhibits gastric hypermotility.In addition,selective COX-2 inhibitors have deleterious influences on the stomach when COX-2 is overexpressed under various conditions,including adrenalectomy,arthritis,and Helicobacter pylori-infection.In summary,gastric hypermotility plays a primary role in the pathogenesis of NSAID-induced gastric damage,and the response,causally related with PG deficiency due to COX-1 inhibition,occurs prior to other pathogenic events such as increased mucosal permeability;and the ulcerogenic properties of NSAIDs require the inhibition of both COX-1 and COX-2,the inhibition of COX-1 upregulates COX-2 expression in association with gastric hypermotility,and PGs produced by COX-2 counteract the deleterious effect of COX-1 inhibition.展开更多
文摘AIM:To investigate the effect of vitamin E on oxidative stress status in the small intestine of diabetic rats. METHODS:Twenty-four male Wistar rats were randomly divided into three groups:Control (C),non-treated diabetic (NTD) and vitamin E-treated diabetic (VETD) groups. The increases in lipid peroxidation,protein oxidation and superoxide dismutase (SOD) in these three groups was compared after 6 wk. RESULTS:There was no significant difference in catalase activity between NTD and control rats. Compared to NTD rats,the treatment with vitamin E significantly decreased lipid peroxidation and protein oxidation,and also increased catalase activity and SOD. CONCLUSION:The results revealed the occurrence of oxidative stress in the small intestine of diabetic rats. Vitamin E,as an antioxidant,attenuates lipid peroxidation and protein oxidation,and increases antioxidant defense mechanism.
基金Supported by Trakya University Research Fund. TUBAP No. 548
文摘AIM: To investigate whether antioxidants vitamin E and C can retard development of hepatic fibrosis in the bilian/obstructed rats. METHODS: Fifty Wistar albino rats were randomly assigned to 5 groups (10 rats in each). Bile duct was ligated in 40 rats and they were treated as follows: group vitC, vitamin C 10 mg/kg sc daily; group vitE, vitamin E 15 mg/kg sc daily; group vitEC, both of the vitamins; bile duct-ligated (BDL, control) group, physiological saline sc. The fifth group was assigned to sham operation. At the end of fourth week, the rats were decapitated, and hepatic tissue biochemical collagen content and collagen surface area were measured. Hepatic tissue specimens were histopathologically evaluated according to Scheuer system. Serum hyaluronate levels were measured by ELISA method. RESULTS: Despite being higher than sham group, hepatic collagen level was significantly decreased in each of the vitC, vitE and vitEC groups (32.7 ± 1.2, 33.8 ± 2.9, 36.7 ± 0.5 )μg collagen/mg protein, respectively) compared to BDL (48.3 ± 0.6 mg collagen/g protein) (P 〈 0.001 for each vitamin group). Each isolated vitamin C, isolated vitamin E and combined vitamin E/C supplementation prevented the increase in hepatic collagen surface density (7.0% ± 1.1%, 6.2% ± 1.7%, 12.3% ± 2.0%, respectively) compared to BDL (17.4% ± 5.6%) (P 〈 0.05 for each). The same beneficial effect of vitamin C, vitamin E and combined vitamin E/C treatment was also observed on the decrease of serum hyaluronate levels compared to BDL group (P 〈 0.001). The relative liver and spleen weights, serum transaminases, cholestatic enzymes, bilirubins and histopathological inflammation scores were not different between the antioxidant treatment groups and the control. However, fibrosis staging scores were obviously reduced only in the vitamin E/C combination group (vit EC: 2.4 ± 0.8 vs BDL: 3.1 ± 0.7; P 〈 0.05). CONCLUSION: Each antioxidant vitamin E, vitamin C and their combination retard hepatic fibrosis in biliary-obstructed rats. Oxidative stress may play a role in the pathogenesis of hepatic fibrosis in secondary biliary cirrhosis.
文摘Non-a-tocopherols are hydroxymethylated and hydrogenated to produce α-tocopherol in one pot process by simultaneously reacting with paraformaldehyde and hydrogen in the presence of catalysts of benzenesulfonic acid and 5% Pd/C in an autoclave. Effects of various operation conditions have been studied. The preferable reaction conditions are: temperature 180 ℃ to 200 ℃, pressure 5.0 MPa, acid concentration 0.5 g/100 ml ethanol, mass ratio of Pd/C to tocopherols 7.1 g/100 g, and reaction time 5.0 h. A product with α-tocopherol content of 80% was obtained by using a raw material with a total tocopherols content of 80.54%. The conversion of non-α-tocopherols is almost 100%, and the mole yield of a-tocopherol is more than 90%.
文摘Tocopherol is the most active vitamin and natural antioxidant existing in the nature known as vitamin E. Lacking of this vitamin makes drastic exchanges on the health of the living organisms. Their active chemical form is l-α-tocopherol substance. In this article, α-thiotocopherol a tocopherol derivative was synthesized via a precursor like dl-α-tocopherol, which has better antioxidant than natural α-tocopherol. And the last compound after separation and purification via TLC and PC procedures was analyzed by FTIR, GC-MS and elemental analysis, oxidative stability is tested with TGA method in air showing roughly antioxidant effect. Another approach is measurment of redox potential against a reference electrode under inert nitrogen atmosphere.
基金supported by Shanghai Municipal Education Commission (Grant no.egd08025)
文摘The aim of this article is to develop a structural equation model to assess key factors of residents' support for hosting mega event based on previous literature.The model consisted of five latent constructs and eight path hypotheses.A survey was conducted in Shanghai before 2010 World Expo.It was found that the support for mega events is affected directly and/or indirectly by four determinants factors:perceived benefits,perceived costs,personal benefits and community attachment,and support relies heavily on perceived benefits rather than costs.This study contributes to the existing body of knowledge in an attempt to understand local residents' support for a mega event in different economic and cultural settings.
基金Supported by the Fundamental Research Funds for the Central Universities and the State Key Development Program for Basic Research of China(2007CB714304)
文摘Vitamin E succinate was synthesized in organic solvents using a modified Novozym-435 as catalyst.In order to improve the catalytic performance of Novozym-435,the enzyme was modified using acetic anhydride, propionic anhydride and succinic anhydride separately.We found that both the hydrolytic activity and the thermal stability of the modified Novozym-435 were enhanced compared with the unmodified enzyme.The modified Novozym-435 catalysts were used to synthesize the succinate derivative of vitamin E.Compared with the native Novozym-435,the catalytic activity of the modified novozym-435 in promoting the synthesis of vitamin E succinate was dramatically increased,with the novozym-435 modified with succinic anhydride(N435-S)as the most active catalyst.Conditions for the synthesis of vitamin E succinate were also optimized.A mixture of tert-butanol and DMSO(volume ratio of 2︰3)was the most suitable medium for the reaction,whereas the appropriate molar ratio of vitamin E to succinic anhydride and reaction temperature were 1︰5 and 40°C,respectively.Under these reaction conditions,the yield of vitamin E succinate reached 94.4%.N435-S could be reused for five batches.
文摘Objective: To explore the frequency and significance of ApoE gene polymorphisms in Chinese patients with atherosclerotic cerebral infarction (ACI). Methods: Polymerase chain reaction and gene sequencing, single nucleotide polymorphisms of ApoE gene were used to analyze 33 cases of patients with ACI and 35 controls. Results: The frequencies of ApoE gene single nucleotide polymorphisms 465C/G, 462C/G and 451delC in the ACI group were significantly higher than those in the control group (P<0.05). The prevalence of polymorphism 486G/T in the control group was significantly higher than that in the ACI group ( P = 0.011) . Conclusions: 465C/G,462C/G and 451delC polymorphisms might be associated with ACI.486GT allele might have protective effect on the pathogenesis of ACI.
文摘Objective: We aimed to investigate protective effects ofvit E on oxidative stress status and homocysteine (Hey) in cardiac tissue of diabetic rats. Methods: Sixteen Wistar male rats were treated with STZ (streptozotocin) (60 mg/kg) to induce diabetes. Diabetic rats were divided into two groups: NTD (non-treated diabetic) and VETD (vit E-treated diabetic) rats. The VETD group received 300 mg/kg vit E with daily feeding. Eight normal rats of the same age were used as the control group. After 6 weeks, the rats were anesthetized, their cardiac tissue was removed, and homogenated supernatant was separated. Samples were assayed for TAC (total antioxidant capacity), LPO (lipid peroxidation), nitrite (NO2), nitrate (NO3), and Hcy. Key Findings: The contents of LPO, NO3 and Hcy in NTD compared to control group indicate a significant increase, but the levels of these parameters decreased in VETD (p 〈 0.05). There was a significant decrease in the amount of TAC in the NTD group but in VETD group, that significantly increased (p 〈 0.05). The amount of NO2 in NTD and VETD groups, compared to the control group, did not show any significant changes (p 〉 0.05). Conclusions: Significant decrease of oxidative stress and Hey in the cardiac tissue caused by vit E supplementation strongly indicated that this radical scavenger may promote a protective effect on diabetic cardiomyopathy through the attenuation of oxidative stress and increase antioxidant defense mechanism.
文摘For more than two decades, immunologists have been using the so-called Th1/Th2 paradigm to explain most of the phenomena related to adaptive immunity. The Thl/Th2 paradigm implied the existence of two different, mutu- ally regulated, CD4+ T helper subsets: Thl cells, driving cell-mediated immune responses involved in tissue damage and fighting infection against intracellular parasites; and Th2 cells that mediate IgE production and are particu- larly involved in eosinophilic inflammation, allergy and clearance of helminthic infections. A third member of the T helper set, IL-17-producing CD4+ T cells, now called Th17 cells, was recently described as a distinct lineage that does not share developmental pathways with either Thl or Th2 cells. The Th17 subset has been linked to autoimmune disorders, being able to produce IL-17, IL-17F and IL-21 among other inflammatory cytokines. Interestingly, it has been reported that there is not only a cross-regulation among Thl, Th2 and Th17 effector cells but there is also a di- chotomy in the generation of Th17 and T regulatory cells. Therefore, Treg and Th17 effector cells arise in a mutually exclusive fashion, depending on whether they are activated in the presence of TGF-β or TGF-β plus inflammatory cytokines such as IL-6. This review will address the discovery of the Th17 cells, and recent progress on their development and regulation.
基金This work was supported by the National Natural Science Foundation of China(No.11602121)the Program for Scientific Research Innovation Team in Colleges and Universities of Ji’nan(No.2018GXRC006).
文摘In order to search for high energy density materials,various 4,8-dihydrodifurazano[3,4-b,e]pyrazine based energetic materials were designed.Density functional theory was employed to investigate the relationships between the structures and properties.The calculated results indicated that the properties of these designed compounds were influenced by the energetic groups and heterocyclic substituents.The-N3 energetic group was found to be the most effective substituent to improve the heats of formation of the designed compounds while the tetrazole ring/-C(NO_(2))_(3) group contributed much to the values of detonation properties.The analysis of bond orders and bond dissociation energies showed that the addition of-NHNH2,-NHNO_(2),-CH(NO_(2))_(3) and-C(NO_(2))_(3) groups would decrease the bond dissociation energies remarkably.Compounds A8,B8,C8,D8,E8,and F8 were finally screened as the potential candidates for high energy density materials since these compounds possess excellent detonation properties and acceptable thermal stabilities.Additionally,the electronic structures of the screened compounds were calculated.
文摘UDP-glucose pyrophosphorylase is an important enzyme concerned with carbohydrate metabolism in plants. Cloning of UGPase is a premise for further study on molecular level, and it is also crucial for study of carbohydrate metabolism. UGPase cDNA sequence as a template, designed primer, then 3'-untranslate region (3' UTR) of UGPase were amplified by 3'-rapid amplification of cDNA ends (3'-RACE). The results suggested the 3' UTR were 243 bp, contained AATAA sequence and Poly(A).
文摘This article reviews the pathogenic mechanism of nonsteroidal anti-inflammatory drug(NSAID)-induced gastric damage,focusing on the relation between cyclooxygenase(COX) inhibition and various functional events.NSAIDs,such as indomethacin,at a dose that inhibits prostaglandin(PG) production,enhance gastric motility,resulting in an increase in mucosal permeability,neutrophil infiltration and oxyradical production,and eventually producing gastric lesions.These lesions are prevented by pretreatment with PGE 2 and antisecretory drugs,and also via an atropine-sensitive mechanism,not related to antisecretory action.Although neither rofecoxib(a selective COX-2 inhibitor) nor SC-560(a selective COX-1 inhibitor) alone damages the stomach,the combined administration of these drugs provokes gastric lesions.SC-560,but not rofecoxib,decreases prostaglandin E 2(PGE 2) production and causes gastric hypermotility and an increase in mucosal permeability.COX-2 mRNA is expressed in the stomach after administration of indomethacin and SC-560 but not rofecoxib.The up-regulation of indomethacin-induced COX-2 expression is prevented by atropine at a dose that inhibits gastric hypermotility.In addition,selective COX-2 inhibitors have deleterious influences on the stomach when COX-2 is overexpressed under various conditions,including adrenalectomy,arthritis,and Helicobacter pylori-infection.In summary,gastric hypermotility plays a primary role in the pathogenesis of NSAID-induced gastric damage,and the response,causally related with PG deficiency due to COX-1 inhibition,occurs prior to other pathogenic events such as increased mucosal permeability;and the ulcerogenic properties of NSAIDs require the inhibition of both COX-1 and COX-2,the inhibition of COX-1 upregulates COX-2 expression in association with gastric hypermotility,and PGs produced by COX-2 counteract the deleterious effect of COX-1 inhibition.