Genistein is one of several isoflavones that has a structure similar to 17β-estradiol, has a strong antioxidant effect, and a high affinity to estrogen receptors. At 15 weeks after ovariectomy, the expression of Bcl-...Genistein is one of several isoflavones that has a structure similar to 17β-estradiol, has a strong antioxidant effect, and a high affinity to estrogen receptors. At 15 weeks after ovariectomy, the expression of Bcl-2 in the hippocampus of rats decreased and Bax expression increased, with an obvious upregulation of apoptosis. However, intraperitoneal injection of genistein or 17β-estradiol for 15 consecutive weeks from the second day after operation upregulated Bcl-2 protein expression downregulated Bax protein expression, and attenuated hippocampal neuron apoptosis. Our experimental findings indicate that long-term intervention with genistein can lead to a decrease in apoptosis in hippocampal neurons following ovadectomy, upregulate the expression of Bcl-2, and downregulate the expression of Bax. In addition, genistein and 17β-estradiol play equal anti-apoptotic and neuroprotective roles.展开更多
Triboelectric nanogenerators(TENGs) have shown promising potential for large-scale blue energy harvesting. However, the lack of reasonable designs has largely hindered TENG from harvesting energy from both rough and t...Triboelectric nanogenerators(TENGs) have shown promising potential for large-scale blue energy harvesting. However, the lack of reasonable designs has largely hindered TENG from harvesting energy from both rough and tranquil seas. Herein, a fully symmetrical triboelectric nanogenerator based on an elliptical cylindrical structure(EC-TENG) is proposed for all-weather blue energy harvesting. The novel elliptical cylindrical shell provides a unique selfstability, high sensitivity to wave triggering, and most importantly, an anti-overturning capability for the EC-TENG. Moreover, benefiting from its internal symmetrical design, the EC-TENG can produce energy normally, even if it was overturned under a rude oscillation in the rough seas, which distinguishes this work from previous reported TENGs. The working mechanism and output performance are systematically studied. The as-fabricated EC-TENG is capable of lighting 400 light-emitting diodes and driving small electronics. More than that, an automatic monitoring system powered by the EC-TENG can also monitor the water level in real-time and provide an alarm if necessary. This work presents an innovative and reliable approach toward all-weather wave energy harvesting in actual marine environments.展开更多
BACKGROUND： Endoplasmic reticulum （ER） stress impairs ER functions and leads to the accumulation of unfolded or misfolded proteins in the ER lumen. ER stress-induced cell death plays an important role in cerebral i...BACKGROUND： Endoplasmic reticulum （ER） stress impairs ER functions and leads to the accumulation of unfolded or misfolded proteins in the ER lumen. ER stress-induced cell death plays an important role in cerebral ischemia. Edaravon （3-methyl-1-phenyl-2-pyrazolin-5-one） is a potent and novel scavenger of free radicals that inhibit delayed neuronal death, as demonstrated by in vitro and animal studies. However, its effect on ER stress and induced neuronal apoptosis in a rat model of brief middle cerebral artery occlusion remains unclear. OBJECTIVE： To explore the effects of edaravone on the expression of ER stress-related factors and neuronal apoptosis, based on the hypothesis that edaravone influences ER stress in a rat model of cerebral ischemia/reperfusion. DESIGN, TIME AND SETTING： A randomized, controlled, animal study was performed at the Laboratory of Department of Neurology, Xiangya Hospital and the Department of Laboratory Animals, Xiangya Medical College, Central South University in China from June 2005 to May 2006. MATERIALS： Edaravone was purchased from Simcere Pharmaceutical Group, China. METHODS： A total of 216 adult, male, Sprague Dawley rats were randomly assigned to sham-surgery, model and edaravone groups, with 72 rats in each group, Brief middle cerebral artery occlusion was established in the model and edaravone groups. In addition, the edaravone group rats were injected with 3 mg/kg edaravone through the tail vein. MAIN OUTCOME MEASURES： RNA-dependent protein kinase-like endoplasmic reticulum eukaryotic translation initiation factor 2a kinase （PERK） and C/EBP homology protein （CHOP） mRNA expression in the ischemic parietal cortex was determined by reverse transcriptionpolymerase chain reaction; phosphorylated PERK and CHOP protein expression was detected by immunohistochemistry; neuronal apoptosis was detected by TdT-mediated-dUTP nick end labeling. RESULTS： Neurological deficit scores were significantly reduced in the edaravone group compared to the model group at 12, 24, and 72 hours following reperfusion （P〈 0.05）. In addition, PERK and CHOP mRNA as well as phosphorylated PERK and CHOP protein expression were significantly reduced in the edaravone group compared to the model group at 1,3, and 6 hours following reperfusion （P 〈 0.05, P 〈 0.01）. CHOP mRNA expression was decreased in the edaravone group compared to the model group at 3, 6, 12, and 24 hours following reperfusion （P〈 0.01）, while CHOP protein expression was less than the model group at 6, 12, and 24 hours following reperfusion （P 〈 0.05）. CONCLUSION： Edaravone treatment resulted in decreased PERK and CHOP expression following ischemia/reperfusion, as well as reduced neuronal apoptosis. Edaravone exhibited a neuroprotective role by inhibiting endoplasmic reticulum stress.展开更多
BACKGROUND：Previous studies have focused on the correlation between Nogo-A expression and multiple sclerosis or between Nogo-A receptor （NgR） expression and multiple sclerosis in the central nervous system. Express...BACKGROUND：Previous studies have focused on the correlation between Nogo-A expression and multiple sclerosis or between Nogo-A receptor （NgR） expression and multiple sclerosis in the central nervous system. Expression patterns of Nogo-A and NgR remain poorly understood in rat models of experimental autoimmune encephalomyelitis （EAE）.OBJECTIVE：To observe dynamic changes in Nogo-A and NgR protein expression, and to verify the correlation between Nogo-A and NgR protein, as well as expression patterns at various time points, in periventricular tissue of EAE rats.DESIGN, TIME AND SETrlNG：A neuroimmunological, randomized, controlled experiment was performed at the Clinical Institute of Hunan People＇s Hospital of China from September to November 2008.MATERIALS：Immunohistochemistry （streptavidin-biotin-peroxidase complex method） kit was purchased from Boster, China.METHODS：A total of 60 female, Wistar rats, aged 6-8 weeks, ware randomly assigned to EAE and control groups （n = 30, respectively）. Guinea pig spinal cord homogenate, self-made complete Freund＇s adjuvant （0.2 mL/100 g）, and pertussis vaccine （0.2 mL） were subcutaneously injected into the hindlimb foot pad of rats from the EAE group to create rat models of EAE. Complete Freund＇s adjuvant （0.2 mL） was infused into rats from the control group.MAIN OUTCOME MEASURES：Nogo-A and NgR protein expression was determined in periventricular white matter using immunohistochemical methods. Neurological scores ware determined in all rats.RESULTS：Rats from the EAE group developed acute-onset EAE following immunization. The pathogenetic symptoms reached a peak on day 15, and neurological scores ware also greatest at this time point. Neurological scores decreased with recovery of the illness. Nogo-A was shown to be expressed in neuronal cells and oligodendrocytes, and expression increased 11 days after immunization （P 〈 0.01）, decreased by day 13 （P 〈 0.01）, and then increased again by day 15. Nogo-A expression remained greater in the EAE group compared with the control group at day 30 （P 〈 0.01）. In the EAE group, NgR protein was primarily expressed on the surface of neuronal bodies and axons. NgR expression increased 13-18 days after immunization （P 〈 0.01 or P 〈 0.05）.CONCLUSION：Nogo-A and NgR protein expression altered with disease course in periventdcular white matter of EAE rats. Results suggested that Nogo-A and NgR were involved in EAE occurrence.展开更多
BACKGROUND： In vitro cultures of neural stem cells have shown that estrogen can regulate beta-amyloid precursor protein （β-APP） metabolism and reduce amyloid-beta production. OBJECTIVE： To investigate the effects...BACKGROUND： In vitro cultures of neural stem cells have shown that estrogen can regulate beta-amyloid precursor protein （β-APP） metabolism and reduce amyloid-beta production. OBJECTIVE： To investigate the effects of long-term oral administration of compound nylestriol or low-dose 17beta-estradiol on β-APP and mRNA expression in the hippocampus of ovariectomized （OVX） rats. DESIGN, TIME AND SETTING： This randomized and controlled experiment was performed at the Animal Laboratory and Laboratory of Endocrine and Metabolic Disease, Xiangya Second Hospital of Central South University between April 2003 and May 2004. MATERIALS： According to body mass, 50 six-month-old female Sprague-Dawley rats were randomly divided into five groups （n = 10 per group）： normal control, sham operation, OVX model, 17beta-estradiol （Sigma, USA）, and compound nylestriol tablet （Laboratory of Endocrine and Metabolic Disease, Xiangya Second Hospital of Central South University） groups. METHODS： Rats in OVX plus 17beta-estradiol and OVX plus compound nylestriol tablet groups underwent ovariectomy. On the second day after surgery, rats were intragastrically given 17beta-estradiol （100 μg/kg）, once per day or compound nylestriol tablet （0.5 mg/kg） and levonorgestrel （0.15 mg/kg） every 2 days. MAIN OUTCOME MEASURES： β-APP expression in the hippocampus of OVX rats was determined using immunohistochemistry （SABC method） and β-APP mRNA expression was analyzed by in situ hybridization. The results were quantitatively analyzed using cell counting and average optical density. RESULTS： The number and optical density of β-APP-positive neurons in every subregion of the hippocampus of OVX rats was dramatically increased compared with normal and sham operation groups following 35 weeks of administration （P 〈 0.05）. Levels of β-APP were decreased following oral administration of compound nylestriol or 17beta-estradiol. In situ hybridization showed that long-term estrogen deficiency and oral administration of compound nylestriol or 17beta-estradiol did not alter the number of β-APP mRNA-positive neurons. CONCLUSION： The results show that long-term estrogen deficiency results in an increase of expression of β-APP though no changes in the expression of β-APP mRNA are detected. Replacement of estrogen with low-dose 17 beta-estradiol or compound nylestriol tablet inhibits the expression of β-APP in the hippocampus to the same extent.展开更多
BACKGROUND： Phytoestrogen, derived from plants, is an estrogen-like element, and is effective and safe for estrogen replacement. OBJECTIVE： To compare the interventional effects of genistein and 17 S-estradiol on le...BACKGROUND： Phytoestrogen, derived from plants, is an estrogen-like element, and is effective and safe for estrogen replacement. OBJECTIVE： To compare the interventional effects of genistein and 17 S-estradiol on learning and memory and synaptophysin （SYN） expression in the hippocampus of ovariectomized rats.DESIGN： Randomized controlled animal study.SETTING： Department of Neurology, the Third Affiliated Hospital, Xiangya Medical College, Central South University. MATERIALS： 130 healthy female Sprague Dawley （SD） rats, 6 months old and weighing （293.1 ± 10.2） g, were provided by the Second Xiangya Hospital of Central South University. This animal experiment received confirmed consent from the local ethics committee. All rats were randomly divided into 5 groups, including baseline group （n= 10）, sham operation group （n = 30）, ovariectomized group （n = 30）, genistein group （n = 30）, and 17 β -estradiol group （n = 30）. Rats in the latter four groups were observed for 3 weeks （n = 10） and for 15 weeks （n = 20） after model establishment. METHODS： This study was performed at the Department of Endocrinology, the Second Affiliated Hospital, Xiangya Medical College, Central South University from August 2005 to January 2006. Animals were not submitted to any treatment in the baseline group, but anesthetized and sacrificed at the 7 months of age. After anesthesia in the ovariectomized, genistein, and 17 S-estradiol groups, both ovaries were separated and resected to establish an ovariectomized model. The same volume of fat was resected in the sham operation group. After surgery, rats were intraperitoneally injected with 5 mg/kg genistein in the genistein group,10μg/kg 17 β -estradiol in the 17 β-estradiol group, and 0.1 mL/100 g dimethyl sulfoxide （DMSO）/polyethylene glycol （PEG）-200 stock solution in the sham operation and ovariectomized groups once a day until one day before sacrifice. MAIN OUTCOME MEASURES：① Learning and memory changes of SD rats were detected using water maze behavioral testing 3 and 15 weeks after surgery. ② SYN expression in the hippocampus was measured using immunohistochemistry. RESULTS： A total of 16 out of 130 rats died due to infection, and 114 rats were included in the final analysis. ① Comparison of water maze results from the five groups： by 3 and 15 weeks after surgery, escape latency was prolonged and platform-crossing times decreased in the ovariectomized group compared to the baseline, genistein, 17 β-estradiol, and sham operation groups （t = 4.17 14.64, P 〈 0.05）. However, there were no significant differences in escape latency and platform-crossing times among the sham operation, genistein, and 17 S-estradiol groups （P 〉 0.05）. ② Distribution and quantity of SYN immunoreactive products in hippocampus： SYN-immunoreactive cells stained darkly in the baseline and sham operation groups, but were lightly stained in the genistein, 17 S -estradiol, and ovariectomized groups. In particular, SYN-immunoreactive cells stained lightly in the ovariectomized group 15 weeks after surgery. SYN correction gray values in hippocampal sub-regions, especially in the mossy fiber layer of the CA3 region, of the ovariectomized group was lower compared to the baseline, sham operation, 17 β -estradiol, and genistein groups （t = 12.57 23.92, P 〈 0.05） 15 weeks after surgery. However, there were no significant differences in SYN correction gray values among the baseline, sham operation, 17 β -estradiol and genistein groups （P 〉 0.05）. CONCLUSION： Genistein or 17 β -estradiol supplemental therapy antagonizes memory deterioration, due to endogenous estrogen deficiency and blocks the decrease of SYN expression in the hippocampus. The effect of genistein is similar to 17 β -estradiol.展开更多
Solid solution strengthening(SSS)is one of the main contributions to the desired tensile properties of nickel-based superalloys for turbine blades and disks.The value of SSS can be calculated by using Fleischer’s and...Solid solution strengthening(SSS)is one of the main contributions to the desired tensile properties of nickel-based superalloys for turbine blades and disks.The value of SSS can be calculated by using Fleischer’s and Labusch’s theories,while the model parameters are incorporated without fitting to experimental data of complex alloys.In thiswork,four diffusionmultiples consisting of multicomponent alloys and pure Niare prepared and characterized.The composition and microhardness of singleγphase regions in samples are used to quantify the SSS.Then,Fleischer’s and Labusch’s theories are examined based on high-throughput experiments,respectively.The fitted solid solution coefficients are obtained based on Labusch’s theory and experimental data,indicating higher accuracy.Furthermore,six machine learning algorithms are established,providing a more accurate prediction compared with traditional physical models and fitted physical models.The results show that the coupling of highthroughput experiments and machine learning has great potential in the field of performance prediction and alloy design.展开更多
In this work,the flow behaviors and microstructure evolution of a powder metallurgy nickel-based superalloy during superplastic compression is investigated.Based on the strain rate sensitivity m determined by flow dat...In this work,the flow behaviors and microstructure evolution of a powder metallurgy nickel-based superalloy during superplastic compression is investigated.Based on the strain rate sensitivity m determined by flow data,superplastic region is estimated at relatively low temperature and strain rate domains,specifically around 1000℃/10^-3s^-1.Thereafter,the cylinder specimens are isothermally compressed at 1000℃/10^-3s^-1 and 1025℃/10^-3s^-1 with different strains,to exam the superplasticity and related mechanisms.The experimental results indicate that the accumulated dislocations are mainly annihilated by dynamic recovery and dynamic recrystallization(DRX),and the grain boundary sliding(GBS)contributes to the total strain during superplastic compression as well.In addition,the cavities and cracks at triple junctions or interfaces between matrix and second phase particle have not been detected,which is different from superplastic tensile deformation.展开更多
The hot deformation behaviors of nickel-based oxide dispersion strengthened(ODS)superalloys fabricated by mechanical alloying(MA)and hot extrusion(HEX)were investigated,the hot compression tests were performed to obta...The hot deformation behaviors of nickel-based oxide dispersion strengthened(ODS)superalloys fabricated by mechanical alloying(MA)and hot extrusion(HEX)were investigated,the hot compression tests were performed to obtain true stress-true strain curves,the influence of strain rate and temperature connected with the microstructure evolution was analyzed,and the processing map and microstructure proposed at different strain levels was used to select its hot working parameters.The results illustrated that hot working conditions,especially the temperature,strongly influenced the grain structure.Specifi-cally,deforming under high temperatures and low strain rate conditions enhances dynamic softening via dynamic recovery(DRV),dynamic recrystallization(DRX),and grain growth to consume the stored strain energy.In addition,the size and morphology of nanoparticles are not significantly changed before and after deformation,the nanoparticles and the matrix still maintain a good interface combination,and no interfacial mismatch such as nanosvoids between the nanoparticle and matrix is detected due to their outstanding interfacial binding ability and excellent ductility of matrix.展开更多
基金supported by Hunan Provincial Traditional Medicine Administration Bureau,No.2010044
文摘Genistein is one of several isoflavones that has a structure similar to 17β-estradiol, has a strong antioxidant effect, and a high affinity to estrogen receptors. At 15 weeks after ovariectomy, the expression of Bcl-2 in the hippocampus of rats decreased and Bax expression increased, with an obvious upregulation of apoptosis. However, intraperitoneal injection of genistein or 17β-estradiol for 15 consecutive weeks from the second day after operation upregulated Bcl-2 protein expression downregulated Bax protein expression, and attenuated hippocampal neuron apoptosis. Our experimental findings indicate that long-term intervention with genistein can lead to a decrease in apoptosis in hippocampal neurons following ovadectomy, upregulate the expression of Bcl-2, and downregulate the expression of Bax. In addition, genistein and 17β-estradiol play equal anti-apoptotic and neuroprotective roles.
基金the financial support from the National Key Research and Development Project(Grant No.2021YFA1201602)National Natural Science Foundation of China(Grant No.52076024)+3 种基金Guangxi Natural Science Foundation Project(Grant No.2021GXNSFAA075009)Guangxi Science and Technology Project(Grant No.GUIKEAD22035178)Natural Science Foundation of Chongqing(Grant No.cstc2021jcyjmsxmX0625)the Fundamental Research Funds for the Central Universities(Grant No.2020CDCGJ005)。
文摘Triboelectric nanogenerators(TENGs) have shown promising potential for large-scale blue energy harvesting. However, the lack of reasonable designs has largely hindered TENG from harvesting energy from both rough and tranquil seas. Herein, a fully symmetrical triboelectric nanogenerator based on an elliptical cylindrical structure(EC-TENG) is proposed for all-weather blue energy harvesting. The novel elliptical cylindrical shell provides a unique selfstability, high sensitivity to wave triggering, and most importantly, an anti-overturning capability for the EC-TENG. Moreover, benefiting from its internal symmetrical design, the EC-TENG can produce energy normally, even if it was overturned under a rude oscillation in the rough seas, which distinguishes this work from previous reported TENGs. The working mechanism and output performance are systematically studied. The as-fabricated EC-TENG is capable of lighting 400 light-emitting diodes and driving small electronics. More than that, an automatic monitoring system powered by the EC-TENG can also monitor the water level in real-time and provide an alarm if necessary. This work presents an innovative and reliable approach toward all-weather wave energy harvesting in actual marine environments.
文摘BACKGROUND： Endoplasmic reticulum （ER） stress impairs ER functions and leads to the accumulation of unfolded or misfolded proteins in the ER lumen. ER stress-induced cell death plays an important role in cerebral ischemia. Edaravon （3-methyl-1-phenyl-2-pyrazolin-5-one） is a potent and novel scavenger of free radicals that inhibit delayed neuronal death, as demonstrated by in vitro and animal studies. However, its effect on ER stress and induced neuronal apoptosis in a rat model of brief middle cerebral artery occlusion remains unclear. OBJECTIVE： To explore the effects of edaravone on the expression of ER stress-related factors and neuronal apoptosis, based on the hypothesis that edaravone influences ER stress in a rat model of cerebral ischemia/reperfusion. DESIGN, TIME AND SETTING： A randomized, controlled, animal study was performed at the Laboratory of Department of Neurology, Xiangya Hospital and the Department of Laboratory Animals, Xiangya Medical College, Central South University in China from June 2005 to May 2006. MATERIALS： Edaravone was purchased from Simcere Pharmaceutical Group, China. METHODS： A total of 216 adult, male, Sprague Dawley rats were randomly assigned to sham-surgery, model and edaravone groups, with 72 rats in each group, Brief middle cerebral artery occlusion was established in the model and edaravone groups. In addition, the edaravone group rats were injected with 3 mg/kg edaravone through the tail vein. MAIN OUTCOME MEASURES： RNA-dependent protein kinase-like endoplasmic reticulum eukaryotic translation initiation factor 2a kinase （PERK） and C/EBP homology protein （CHOP） mRNA expression in the ischemic parietal cortex was determined by reverse transcriptionpolymerase chain reaction; phosphorylated PERK and CHOP protein expression was detected by immunohistochemistry; neuronal apoptosis was detected by TdT-mediated-dUTP nick end labeling. RESULTS： Neurological deficit scores were significantly reduced in the edaravone group compared to the model group at 12, 24, and 72 hours following reperfusion （P〈 0.05）. In addition, PERK and CHOP mRNA as well as phosphorylated PERK and CHOP protein expression were significantly reduced in the edaravone group compared to the model group at 1,3, and 6 hours following reperfusion （P 〈 0.05, P 〈 0.01）. CHOP mRNA expression was decreased in the edaravone group compared to the model group at 3, 6, 12, and 24 hours following reperfusion （P〈 0.01）, while CHOP protein expression was less than the model group at 6, 12, and 24 hours following reperfusion （P 〈 0.05）. CONCLUSION： Edaravone treatment resulted in decreased PERK and CHOP expression following ischemia/reperfusion, as well as reduced neuronal apoptosis. Edaravone exhibited a neuroprotective role by inhibiting endoplasmic reticulum stress.
文摘BACKGROUND：Previous studies have focused on the correlation between Nogo-A expression and multiple sclerosis or between Nogo-A receptor （NgR） expression and multiple sclerosis in the central nervous system. Expression patterns of Nogo-A and NgR remain poorly understood in rat models of experimental autoimmune encephalomyelitis （EAE）.OBJECTIVE：To observe dynamic changes in Nogo-A and NgR protein expression, and to verify the correlation between Nogo-A and NgR protein, as well as expression patterns at various time points, in periventricular tissue of EAE rats.DESIGN, TIME AND SETrlNG：A neuroimmunological, randomized, controlled experiment was performed at the Clinical Institute of Hunan People＇s Hospital of China from September to November 2008.MATERIALS：Immunohistochemistry （streptavidin-biotin-peroxidase complex method） kit was purchased from Boster, China.METHODS：A total of 60 female, Wistar rats, aged 6-8 weeks, ware randomly assigned to EAE and control groups （n = 30, respectively）. Guinea pig spinal cord homogenate, self-made complete Freund＇s adjuvant （0.2 mL/100 g）, and pertussis vaccine （0.2 mL） were subcutaneously injected into the hindlimb foot pad of rats from the EAE group to create rat models of EAE. Complete Freund＇s adjuvant （0.2 mL） was infused into rats from the control group.MAIN OUTCOME MEASURES：Nogo-A and NgR protein expression was determined in periventricular white matter using immunohistochemical methods. Neurological scores ware determined in all rats.RESULTS：Rats from the EAE group developed acute-onset EAE following immunization. The pathogenetic symptoms reached a peak on day 15, and neurological scores ware also greatest at this time point. Neurological scores decreased with recovery of the illness. Nogo-A was shown to be expressed in neuronal cells and oligodendrocytes, and expression increased 11 days after immunization （P 〈 0.01）, decreased by day 13 （P 〈 0.01）, and then increased again by day 15. Nogo-A expression remained greater in the EAE group compared with the control group at day 30 （P 〈 0.01）. In the EAE group, NgR protein was primarily expressed on the surface of neuronal bodies and axons. NgR expression increased 13-18 days after immunization （P 〈 0.01 or P 〈 0.05）.CONCLUSION：Nogo-A and NgR protein expression altered with disease course in periventdcular white matter of EAE rats. Results suggested that Nogo-A and NgR were involved in EAE occurrence.
基金the National Key Medical Technologies Research and Development Program of China during the Tenth Five-Year Plan Period, No. 2001BA702B03
文摘BACKGROUND： In vitro cultures of neural stem cells have shown that estrogen can regulate beta-amyloid precursor protein （β-APP） metabolism and reduce amyloid-beta production. OBJECTIVE： To investigate the effects of long-term oral administration of compound nylestriol or low-dose 17beta-estradiol on β-APP and mRNA expression in the hippocampus of ovariectomized （OVX） rats. DESIGN, TIME AND SETTING： This randomized and controlled experiment was performed at the Animal Laboratory and Laboratory of Endocrine and Metabolic Disease, Xiangya Second Hospital of Central South University between April 2003 and May 2004. MATERIALS： According to body mass, 50 six-month-old female Sprague-Dawley rats were randomly divided into five groups （n = 10 per group）： normal control, sham operation, OVX model, 17beta-estradiol （Sigma, USA）, and compound nylestriol tablet （Laboratory of Endocrine and Metabolic Disease, Xiangya Second Hospital of Central South University） groups. METHODS： Rats in OVX plus 17beta-estradiol and OVX plus compound nylestriol tablet groups underwent ovariectomy. On the second day after surgery, rats were intragastrically given 17beta-estradiol （100 μg/kg）, once per day or compound nylestriol tablet （0.5 mg/kg） and levonorgestrel （0.15 mg/kg） every 2 days. MAIN OUTCOME MEASURES： β-APP expression in the hippocampus of OVX rats was determined using immunohistochemistry （SABC method） and β-APP mRNA expression was analyzed by in situ hybridization. The results were quantitatively analyzed using cell counting and average optical density. RESULTS： The number and optical density of β-APP-positive neurons in every subregion of the hippocampus of OVX rats was dramatically increased compared with normal and sham operation groups following 35 weeks of administration （P 〈 0.05）. Levels of β-APP were decreased following oral administration of compound nylestriol or 17beta-estradiol. In situ hybridization showed that long-term estrogen deficiency and oral administration of compound nylestriol or 17beta-estradiol did not alter the number of β-APP mRNA-positive neurons. CONCLUSION： The results show that long-term estrogen deficiency results in an increase of expression of β-APP though no changes in the expression of β-APP mRNA are detected. Replacement of estrogen with low-dose 17 beta-estradiol or compound nylestriol tablet inhibits the expression of β-APP in the hippocampus to the same extent.
基金the grants from Hunan Science and Technology Bureau, No. 03SSY4028the grants from Hunan Administration Bureau of Public Health, No. B2006046the grants from Human Development Bureau, No. 2006-773
文摘BACKGROUND： Phytoestrogen, derived from plants, is an estrogen-like element, and is effective and safe for estrogen replacement. OBJECTIVE： To compare the interventional effects of genistein and 17 S-estradiol on learning and memory and synaptophysin （SYN） expression in the hippocampus of ovariectomized rats.DESIGN： Randomized controlled animal study.SETTING： Department of Neurology, the Third Affiliated Hospital, Xiangya Medical College, Central South University. MATERIALS： 130 healthy female Sprague Dawley （SD） rats, 6 months old and weighing （293.1 ± 10.2） g, were provided by the Second Xiangya Hospital of Central South University. This animal experiment received confirmed consent from the local ethics committee. All rats were randomly divided into 5 groups, including baseline group （n= 10）, sham operation group （n = 30）, ovariectomized group （n = 30）, genistein group （n = 30）, and 17 β -estradiol group （n = 30）. Rats in the latter four groups were observed for 3 weeks （n = 10） and for 15 weeks （n = 20） after model establishment. METHODS： This study was performed at the Department of Endocrinology, the Second Affiliated Hospital, Xiangya Medical College, Central South University from August 2005 to January 2006. Animals were not submitted to any treatment in the baseline group, but anesthetized and sacrificed at the 7 months of age. After anesthesia in the ovariectomized, genistein, and 17 S-estradiol groups, both ovaries were separated and resected to establish an ovariectomized model. The same volume of fat was resected in the sham operation group. After surgery, rats were intraperitoneally injected with 5 mg/kg genistein in the genistein group,10μg/kg 17 β -estradiol in the 17 β-estradiol group, and 0.1 mL/100 g dimethyl sulfoxide （DMSO）/polyethylene glycol （PEG）-200 stock solution in the sham operation and ovariectomized groups once a day until one day before sacrifice. MAIN OUTCOME MEASURES：① Learning and memory changes of SD rats were detected using water maze behavioral testing 3 and 15 weeks after surgery. ② SYN expression in the hippocampus was measured using immunohistochemistry. RESULTS： A total of 16 out of 130 rats died due to infection, and 114 rats were included in the final analysis. ① Comparison of water maze results from the five groups： by 3 and 15 weeks after surgery, escape latency was prolonged and platform-crossing times decreased in the ovariectomized group compared to the baseline, genistein, 17 β-estradiol, and sham operation groups （t = 4.17 14.64, P 〈 0.05）. However, there were no significant differences in escape latency and platform-crossing times among the sham operation, genistein, and 17 S-estradiol groups （P 〉 0.05）. ② Distribution and quantity of SYN immunoreactive products in hippocampus： SYN-immunoreactive cells stained darkly in the baseline and sham operation groups, but were lightly stained in the genistein, 17 S -estradiol, and ovariectomized groups. In particular, SYN-immunoreactive cells stained lightly in the ovariectomized group 15 weeks after surgery. SYN correction gray values in hippocampal sub-regions, especially in the mossy fiber layer of the CA3 region, of the ovariectomized group was lower compared to the baseline, sham operation, 17 β -estradiol, and genistein groups （t = 12.57 23.92, P 〈 0.05） 15 weeks after surgery. However, there were no significant differences in SYN correction gray values among the baseline, sham operation, 17 β -estradiol and genistein groups （P 〉 0.05）. CONCLUSION： Genistein or 17 β -estradiol supplemental therapy antagonizes memory deterioration, due to endogenous estrogen deficiency and blocks the decrease of SYN expression in the hippocampus. The effect of genistein is similar to 17 β -estradiol.
基金supported by National Science and Technology Major Project (J2019-IV-0003-0070)the Natural Science Foundation of China (91860105,52074366)+4 种基金China Postdoctoral Science Foundation (2019M662799)Natural Science Foundation of Hunan Province of China (2021JJ40757)the Science and Technology Innovation Program of Hunan Province (2021RC3131)Changsha Municipal Natural Science Foundation (kq2014126)Project Supported by State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.
文摘Solid solution strengthening(SSS)is one of the main contributions to the desired tensile properties of nickel-based superalloys for turbine blades and disks.The value of SSS can be calculated by using Fleischer’s and Labusch’s theories,while the model parameters are incorporated without fitting to experimental data of complex alloys.In thiswork,four diffusionmultiples consisting of multicomponent alloys and pure Niare prepared and characterized.The composition and microhardness of singleγphase regions in samples are used to quantify the SSS.Then,Fleischer’s and Labusch’s theories are examined based on high-throughput experiments,respectively.The fitted solid solution coefficients are obtained based on Labusch’s theory and experimental data,indicating higher accuracy.Furthermore,six machine learning algorithms are established,providing a more accurate prediction compared with traditional physical models and fitted physical models.The results show that the coupling of highthroughput experiments and machine learning has great potential in the field of performance prediction and alloy design.
基金supported financially by the National Key Research and Development Program of China (No.2016YFB0701404)the National Natural Science Foundation of China (No.91860105)the Fund from Innovation and Entrepreneur Team Introduced by Guangdong Province (No. 201301G0105337290)
文摘In this work,the flow behaviors and microstructure evolution of a powder metallurgy nickel-based superalloy during superplastic compression is investigated.Based on the strain rate sensitivity m determined by flow data,superplastic region is estimated at relatively low temperature and strain rate domains,specifically around 1000℃/10^-3s^-1.Thereafter,the cylinder specimens are isothermally compressed at 1000℃/10^-3s^-1 and 1025℃/10^-3s^-1 with different strains,to exam the superplasticity and related mechanisms.The experimental results indicate that the accumulated dislocations are mainly annihilated by dynamic recovery and dynamic recrystallization(DRX),and the grain boundary sliding(GBS)contributes to the total strain during superplastic compression as well.In addition,the cavities and cracks at triple junctions or interfaces between matrix and second phase particle have not been detected,which is different from superplastic tensile deformation.
基金supported by supported by the National Natu-ral Science Foundation of China(No.52271177)the Leading Tal-ents Project of Scientific and Technological Innovation in Hunan Province(No.2021RC4036)the Natural Science Foundation of Hu-nan Province(Nos.2023JJ50172 and 2020JJ6069).
文摘The hot deformation behaviors of nickel-based oxide dispersion strengthened(ODS)superalloys fabricated by mechanical alloying(MA)and hot extrusion(HEX)were investigated,the hot compression tests were performed to obtain true stress-true strain curves,the influence of strain rate and temperature connected with the microstructure evolution was analyzed,and the processing map and microstructure proposed at different strain levels was used to select its hot working parameters.The results illustrated that hot working conditions,especially the temperature,strongly influenced the grain structure.Specifi-cally,deforming under high temperatures and low strain rate conditions enhances dynamic softening via dynamic recovery(DRV),dynamic recrystallization(DRX),and grain growth to consume the stored strain energy.In addition,the size and morphology of nanoparticles are not significantly changed before and after deformation,the nanoparticles and the matrix still maintain a good interface combination,and no interfacial mismatch such as nanosvoids between the nanoparticle and matrix is detected due to their outstanding interfacial binding ability and excellent ductility of matrix.
