Background: Cimetidine, an antagonist of histamine type II receptors, has shown protective effects against γ-rays or neutrons. However, there have been no reports on the effects of cimetidine against neutrons combine...Background: Cimetidine, an antagonist of histamine type II receptors, has shown protective effects against γ-rays or neutrons. However, there have been no reports on the effects of cimetidine against neutrons combined with γ-rays. This study was carried out to evaluate the protective effects of cimetidine on rats exposed to long-term, low-dose-rate neutron and γ-ray combined irradiation(n-γ LDR).Methods: Fifty male Sprague-Dawley(SD) rats were randomly divided into 5 groups: the normal control group, radiation model group, 20mg/(kg·d) cimetidine group, 80mg/(kg·d) cimetidine group and 160mg/(kg·d) cimetidine group(10 rats per group). Except for the normal control group, 40 rats were simultaneously exposed to fission neutrons(^(252)Cf, 0.085 m Gy/h) for 22 h every day and γ-rays(^(60)Co, 0.097Gy/h) for 1.03 h once every three days, and the cimetidine groups were administered intragastrically with cimetidine at doses of 20, 80 and 160mg/kg each day. Peripheral blood WBC of the rats was counted the day following exposure to γ-rays. The rats were anesthetized and sacrificed on the day following exposure to ^(252)Cf for 28 days. The spleen, thymus, testicle, liver and intestinal tract indexes were evaluated. The DNA content of bone marrow cells and concanavalin A(Con A)-induced lymphocyte proliferation were measured. The frequency of micronuclei in polychromatic erythrocytes(f MNPCEs), superoxide dismutase(SOD), malondialdehyde(MDA), and glutathione peroxidase(GSH-Px) in the serum and liver tissues were detected.Results: The peripheral blood WBC in the cimetidine groups was increased significantly on the 8th day and the 26 th day compared with those in the radiation model group. The spleen, thymus and testicle indexes of the cimetidine groups were higher than those of the radiation model group. The DNA content of bone marrow cells and lymphocyte proliferation in the cimetidine groups were increased significantly, and fMNPCE was reduced 1.41-1.77 fold in cimetidine treated groups. The activities of SOD and GSH-Px in the cimetidine groups were increased significantly, and the content of MDA in the cimetidine groups was decreased significantly.Conclusions: The results suggested that cimetidine alleviated damage induced by long-term, low-dose-rate neutron and γ combined irradiation via antioxidation and immunomodulation. Cimetidine might be useful as a potent radioprotector for radiotherapy patients as well as for occupational exposure workers.展开更多
Background: Wounded personnel who work at sea often encounter a plethora of difficulties. The most important of these difficulties is seawater immersion. Common medical dressings have little effect when the affected a...Background: Wounded personnel who work at sea often encounter a plethora of difficulties. The most important of these difficulties is seawater immersion. Common medical dressings have little effect when the affected area is immersed in seawater, and only rarely dressings have been reported for the treatment of seawater-immersed wounds. The objective of this study is to develop a new dressing which should be suitable to prevent the wound from seawater immersion and to promote the wound healing.Methods: Shark skin collagen(SSC) was purified via ethanol de-sugaring and de-pigmentation and adjusted for p H. A shark skin collagen sponge(SSCS) was prepared by freeze-drying. SSCS was attached to an anti-seawater immersion polyurethane(PU) film(SSCS+PU) to compose a new dressing. The biochemical properties of SSC and physicochemical properties of SSCS were assessed by standard methods. The effects of SSCS and SSCS+PU on the healing of seawaterimmersed wounds were studied using a seawater immersion rat model. For the detection of SSCS effects on seawaterimmersed wounds, 12 SD rats, with four wounds created in each rat, were divided into four groups: the 3 rd day group, 5 th day group, 7 th day group and 12 th day group. In each group, six wounds were treated with SSCS, three wounds treated with chitosan served as the positive control, and three wounds treated with gauze served as the negative control. For the detection of the SSCS+PU effects on seawater-immersed wounds, 36 SD rats were divided into three groups: the gauze(GZ)+PU group, chitosan(CS)+PU group and SSCS+PU group, with 12 rats in each group, and two wounds in each rat. The wound sizes were measured to calculate the healing rate, and histomorphology and the immunohistochemistry of the CD31 and TGF-β expression levels in the wounded tissues were measured by standard methods.Results: The results of Ultraviolet-visible(UV-vis) spectrum, Fourier-transform infrared(FTIR) spectrum, circular dichroism(CD) spectra, sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE), and amino acid composition analyses of SSC demonstrated that SSC is type I collagen. SSCS had a homogeneous porous structure of approximately 200μm, porosity rate of 83.57%±2.64%, water vapor transmission ratio(WVTR) of 4500 g/m2, tensile strength of 1.79±0.41 N/mm, and elongation at break of 4.52%±0.01%. SSCS had significant beneficial effects on seawater-immersed wound healing. On the 3 rd day, the healing rates in the GZ negative control, CS positive control and SSCS rats were 13.94%±5.50%, 29.40%±1.10% and 47.24%±8.40%, respectively. SSCS also enhanced TGF-in the initial stage of the healing period. The SSCS+PU dressing effectively protected woundsβ and CD31 expression from seawater immersion for at least 4 h, and accelerated re-epithelialization, vascularization and granulation formation of seawater-immersed wounds in the earlier stages of wound healing, and as well as significantly promoted wound healing. The SSCS+PU dressing also enhanced expression of TGF-n and gauze dressings.β and CD31. The effects of SSCS and SSCS+PU were superior to those of both the chitosaConclusion: SSCS has significant positive effects on the promotion of seawater-immersed wound healing, and a SSCS+PU dressing effectively prevents seawater immersion, and significantly promotes seawater-immersed wound healing.展开更多
In this article, the effect of diethylaluminum chloride (DEAC) in propylene polymerization with MgCl2-supported Ziegler-Natta catalyst was studied. Addition of DEAC in the catalyst system caused evident change in cata...In this article, the effect of diethylaluminum chloride (DEAC) in propylene polymerization with MgCl2-supported Ziegler-Natta catalyst was studied. Addition of DEAC in the catalyst system caused evident change in catalytic activity and polymer chain structure. The activity decrease in raising DEAC/Ti molar ratio from 0 to 2 is a result of depressed production of isotactic polypropylene chains. The number of active centers in fractions of each polymer sample was determined by quenching the polymerization with 2-thiophenecarbonyl chloride and fractionating the polymer into isotactic, medium-isotactic and atactic fractions. The number of active centers in isotactic fraction ([Ci*]/[Ti]) was lowered by increasing DEAC/Ti molar ratio to 2, but further increasing the DEAC/Ti molar ratio to 20 caused marked increase of [Ci*]/[Ti]. The number of active centers that produce atactic and medium-isotactic PP chains was less influenced by DEAC in the range of DEAC/Ti = 0-10, but increased when the DEAC/Ti molar ratio was further raised to 20. The propagation rate constant of Ci * (kpi) was evidently increased when DEAC/Ti molar ratio was raised from 0 to 5, but further increase in DEAC/Ti ratio caused gradual decrease in k pi . The complicated effect of DEAC on the polymerization kinetics, catalysis behaviors and polymer structure can be reasonably explained by adsorption of DEAC on the central metal of the active centers or on Mg atoms adjacent to the central metal.展开更多
基金supported by the Research Fund of National Science and Technology Major Project of China(No.2014ZX09J14103-07B)
文摘Background: Cimetidine, an antagonist of histamine type II receptors, has shown protective effects against γ-rays or neutrons. However, there have been no reports on the effects of cimetidine against neutrons combined with γ-rays. This study was carried out to evaluate the protective effects of cimetidine on rats exposed to long-term, low-dose-rate neutron and γ-ray combined irradiation(n-γ LDR).Methods: Fifty male Sprague-Dawley(SD) rats were randomly divided into 5 groups: the normal control group, radiation model group, 20mg/(kg·d) cimetidine group, 80mg/(kg·d) cimetidine group and 160mg/(kg·d) cimetidine group(10 rats per group). Except for the normal control group, 40 rats were simultaneously exposed to fission neutrons(^(252)Cf, 0.085 m Gy/h) for 22 h every day and γ-rays(^(60)Co, 0.097Gy/h) for 1.03 h once every three days, and the cimetidine groups were administered intragastrically with cimetidine at doses of 20, 80 and 160mg/kg each day. Peripheral blood WBC of the rats was counted the day following exposure to γ-rays. The rats were anesthetized and sacrificed on the day following exposure to ^(252)Cf for 28 days. The spleen, thymus, testicle, liver and intestinal tract indexes were evaluated. The DNA content of bone marrow cells and concanavalin A(Con A)-induced lymphocyte proliferation were measured. The frequency of micronuclei in polychromatic erythrocytes(f MNPCEs), superoxide dismutase(SOD), malondialdehyde(MDA), and glutathione peroxidase(GSH-Px) in the serum and liver tissues were detected.Results: The peripheral blood WBC in the cimetidine groups was increased significantly on the 8th day and the 26 th day compared with those in the radiation model group. The spleen, thymus and testicle indexes of the cimetidine groups were higher than those of the radiation model group. The DNA content of bone marrow cells and lymphocyte proliferation in the cimetidine groups were increased significantly, and fMNPCE was reduced 1.41-1.77 fold in cimetidine treated groups. The activities of SOD and GSH-Px in the cimetidine groups were increased significantly, and the content of MDA in the cimetidine groups was decreased significantly.Conclusions: The results suggested that cimetidine alleviated damage induced by long-term, low-dose-rate neutron and γ combined irradiation via antioxidation and immunomodulation. Cimetidine might be useful as a potent radioprotector for radiotherapy patients as well as for occupational exposure workers.
基金supported by a Major Project of the Ministry of National Science and Technology of China(Grant No.2014ZX09J14103-09C).
文摘Background: Wounded personnel who work at sea often encounter a plethora of difficulties. The most important of these difficulties is seawater immersion. Common medical dressings have little effect when the affected area is immersed in seawater, and only rarely dressings have been reported for the treatment of seawater-immersed wounds. The objective of this study is to develop a new dressing which should be suitable to prevent the wound from seawater immersion and to promote the wound healing.Methods: Shark skin collagen(SSC) was purified via ethanol de-sugaring and de-pigmentation and adjusted for p H. A shark skin collagen sponge(SSCS) was prepared by freeze-drying. SSCS was attached to an anti-seawater immersion polyurethane(PU) film(SSCS+PU) to compose a new dressing. The biochemical properties of SSC and physicochemical properties of SSCS were assessed by standard methods. The effects of SSCS and SSCS+PU on the healing of seawaterimmersed wounds were studied using a seawater immersion rat model. For the detection of SSCS effects on seawaterimmersed wounds, 12 SD rats, with four wounds created in each rat, were divided into four groups: the 3 rd day group, 5 th day group, 7 th day group and 12 th day group. In each group, six wounds were treated with SSCS, three wounds treated with chitosan served as the positive control, and three wounds treated with gauze served as the negative control. For the detection of the SSCS+PU effects on seawater-immersed wounds, 36 SD rats were divided into three groups: the gauze(GZ)+PU group, chitosan(CS)+PU group and SSCS+PU group, with 12 rats in each group, and two wounds in each rat. The wound sizes were measured to calculate the healing rate, and histomorphology and the immunohistochemistry of the CD31 and TGF-β expression levels in the wounded tissues were measured by standard methods.Results: The results of Ultraviolet-visible(UV-vis) spectrum, Fourier-transform infrared(FTIR) spectrum, circular dichroism(CD) spectra, sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE), and amino acid composition analyses of SSC demonstrated that SSC is type I collagen. SSCS had a homogeneous porous structure of approximately 200μm, porosity rate of 83.57%±2.64%, water vapor transmission ratio(WVTR) of 4500 g/m2, tensile strength of 1.79±0.41 N/mm, and elongation at break of 4.52%±0.01%. SSCS had significant beneficial effects on seawater-immersed wound healing. On the 3 rd day, the healing rates in the GZ negative control, CS positive control and SSCS rats were 13.94%±5.50%, 29.40%±1.10% and 47.24%±8.40%, respectively. SSCS also enhanced TGF-in the initial stage of the healing period. The SSCS+PU dressing effectively protected woundsβ and CD31 expression from seawater immersion for at least 4 h, and accelerated re-epithelialization, vascularization and granulation formation of seawater-immersed wounds in the earlier stages of wound healing, and as well as significantly promoted wound healing. The SSCS+PU dressing also enhanced expression of TGF-n and gauze dressings.β and CD31. The effects of SSCS and SSCS+PU were superior to those of both the chitosaConclusion: SSCS has significant positive effects on the promotion of seawater-immersed wound healing, and a SSCS+PU dressing effectively prevents seawater immersion, and significantly promotes seawater-immersed wound healing.
基金supported by the National Natural Science Foundation of China (No. 21074108)the Major State Basic Research Programs (No. 2011CB606001)
文摘In this article, the effect of diethylaluminum chloride (DEAC) in propylene polymerization with MgCl2-supported Ziegler-Natta catalyst was studied. Addition of DEAC in the catalyst system caused evident change in catalytic activity and polymer chain structure. The activity decrease in raising DEAC/Ti molar ratio from 0 to 2 is a result of depressed production of isotactic polypropylene chains. The number of active centers in fractions of each polymer sample was determined by quenching the polymerization with 2-thiophenecarbonyl chloride and fractionating the polymer into isotactic, medium-isotactic and atactic fractions. The number of active centers in isotactic fraction ([Ci*]/[Ti]) was lowered by increasing DEAC/Ti molar ratio to 2, but further increasing the DEAC/Ti molar ratio to 20 caused marked increase of [Ci*]/[Ti]. The number of active centers that produce atactic and medium-isotactic PP chains was less influenced by DEAC in the range of DEAC/Ti = 0-10, but increased when the DEAC/Ti molar ratio was further raised to 20. The propagation rate constant of Ci * (kpi) was evidently increased when DEAC/Ti molar ratio was raised from 0 to 5, but further increase in DEAC/Ti ratio caused gradual decrease in k pi . The complicated effect of DEAC on the polymerization kinetics, catalysis behaviors and polymer structure can be reasonably explained by adsorption of DEAC on the central metal of the active centers or on Mg atoms adjacent to the central metal.
