期刊文献+
共找到271,045篇文章
< 1 2 250 >
每页显示 20 50 100
An Inventory of Fluorspar Production, Industrial Use, and Emissions of Trifluoroacetic Acid (TFA) in the Period 1930 to 1999
1
作者 Andrew A. Lindley 《Journal of Geoscience and Environment Protection》 2023年第3期1-16,共16页
There is a generally accepted conclusion that trifluoroacetic acid (TFA) does occur naturally, in part based on the large quantities of TFA in the oceans (61 - 205 million tonnes, measured in 1998-2002). However, the ... There is a generally accepted conclusion that trifluoroacetic acid (TFA) does occur naturally, in part based on the large quantities of TFA in the oceans (61 - 205 million tonnes, measured in 1998-2002). However, the recent review paper “Insufficient evidence for the existence of natural trifluoroacetic acid” concludes that “the presence of TFA in the deep ocean and lack of closed TFA budget is not sufficient evidence that TFA occurs naturally, especially without a reasonable mechanism of formation”. Industrial sources of TFA can only result from the use of fluoride minerals in industrial processes. Major industrial uses of fluorspar started significant expansion from about the same time (1930s). Over 190 million tonnes of fluorspar have been mined in the period 1930 to 1999. An inventory has been developed (1930-1999), accounting for most of the fluorspar production (86%) and estimating emissions of TFA. Industrial emissions of TFA are estimated as 230,000 to 470,000 tonnes. Significant other industrial uses of fluorides have not been identified that could account for the large burden of TFA in the oceans. This inventory provides complementary evidence that the quantity of TFA in the oceans must include a large natural burden. 展开更多
关键词 FLUORSPAR trifluoroacetic acid TFA HFCS PESTICIDES Aluminium Steel ANAESTHETICS
下载PDF
Determination of Carbon and Nitrogen Isotope Fractions in Tartaric Acid, Oxalic Acid, Glucose and Fructose—National Center of High Technologies of Georgia
2
作者 Lamzira Pharulava Levani Eliashvili +1 位作者 Vakhtang Betlemidze Bachana Sulava 《American Journal of Analytical Chemistry》 CAS 2024年第8期229-240,共12页
Tartaric acid, oxalic acid, glucose, and fructose are highly important compounds. A comprehensive study of these substances is fascinating from a scientific perspective. They are key components found in wine, vegetabl... Tartaric acid, oxalic acid, glucose, and fructose are highly important compounds. A comprehensive study of these substances is fascinating from a scientific perspective. They are key components found in wine, vegetables, and fruits. Understanding the isotopic compositions in organic compounds is crucial for comprehending various biochemical processes and the nature of substances present in different natural products. Tartaric acid, oxalic acid, glucose, and fructose are widely distributed compounds, including in vegetables and fruits. Tartaric acid plays a significant role in determining the quality and taste properties of wine, while oxalic acid is also prevalent but holds great interest for further research, especially in terms of carbon isotopic composition. We can unveil the mechanisms of processes that were previously impossible to study. Glucose and fructose are the most common monosaccharides in the hexose group, and both are found in fruits, with sweeter fruits containing higher amounts of these substances. In addition to fruits, wheat, barley, rye, onions, garlic, lentils, peppers, dried fruits, beans, broccoli, cabbage, tomatoes, and other foods are also rich sources of fructose and glucose. To determine the mass fraction of the carbon-13 isotope in these compounds, it is important to study their changes during natural synthesis. These compounds can be modified with a carbon center. According to the existing isotopic analysis method, these compounds are converted into carbon oxide or dioxide [1]. At this point, the average carbon content in the given compound is determined, but information about isotope-modified centers is lost. Dilution may occur through the transfer of other carbon-containing organic compounds in the sample or by dilution with natural carbon or carbon dioxide during the transfer process. This article discusses the possibility of carbon-13 isotope propagation directly in these compounds, both completely modified and modified with individual carbon centers. The literature provides information on determining carbon-13 substance in organic compounds, both with a general approach and for individual compounds [2] [3]. 展开更多
关键词 Tartaric acid Oxalic acid GLUCOSE FRUCTOSE Mass Spectrum Ion Current Intensity Mass Line Mass Number Molecular and Fragment Ions CARBON Carbon Center
下载PDF
Hyodeoxycholic acid protects the neurovascular unit against oxygen-glucose deprivation and reoxygenation-induced injury in vitro 被引量:15
3
作者 Chang-Xiang Li Xue-Qian Wang +3 位作者 Fa-Feng Cheng Xin Yan Juan Luo Qing-Guo Wang 《Neural Regeneration Research》 SCIE CAS CSCD 2019年第11期1941-1949,共9页
Calculus bovis is commonly used for the treatment of stroke in traditional Chinese medicine. Hyodeoxycholic acid(HDCA) is a bioactive compound extracted from calculus bovis. When combined with cholic acid, baicalin an... Calculus bovis is commonly used for the treatment of stroke in traditional Chinese medicine. Hyodeoxycholic acid(HDCA) is a bioactive compound extracted from calculus bovis. When combined with cholic acid, baicalin and jas-minoidin, HDCA prevents hypoxia-reoxygenation-induced brain injury by suppressing endoplasmic reticulum stress-mediated apoptotic signaling. However, the effects of HDCA in ischemic stroke injury have not yet been studied. Neurovascular unit(NVU) dysfunction occurs in ischemic stroke. Therefore, in this study, we investigated the effects of HDCA on the NVU under ischemic conditions in vitro. We co-cultured primary brain microvascular endothelial cells, neurons and astrocytes using a transwell chamber co-culture system. The NVU was pre-treated with 10.16 or 2.54 μg/mL HDCA for 24 hours before exposure to oxygen-glucose deprivation for 1 hour. The cell counting kit-8 assay was used to detect cell activity. Flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling were used to assess apoptosis. Enzyme-linked immunosorbent assay was used to measure the expression levels of inflammatory cytokines, including interleukin-1β, interleukin-6 and tumor necrosis factor-α, and neurotrophic factors, including brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor. Oxidative stress-related factors, such as superoxide dismutase, nitric oxide, malondialdehyde and γ-glutamyltransferase, were measured using kits. Pretreatment with HDCA significantly decreased blood-brain barrier permeability and neuronal apoptosis, significantly increased transendothelial electrical resistance and γ-glutamyltransferase activity, attenuated oxidative stress damage and the release of inflammatory cytokines, and increased brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor expression. Our findings suggest that HDCA maintains NVU morphological integrity and function by modulating inflammation, oxidation stress, apoptosis, and the expression of neurotrophic factors. Therefore, HDCA may have therapeutic potential in the clinical management of ischemic stroke. This study was approved by the Ethics Committee of Experimental Animals of Beijing University of Chinese Medicine(approval No. BUCM-3-2016040201-2003) in April 2016. 展开更多
关键词 hyodeoxycholic acid oxygen glucose deprivation and REOXYGENATION blood-brain barrier permeability anti-oxidative anti-inflammatory ANTI-APOPTOTIC BRAIN-DERIVED NEUROTROPHIC FACTOR glial cell line-derived NEUROTROPHIC FACTOR ischemic stroke in vitro NEUROVASCULAR unit
下载PDF
Six Amino Acids among Natural Moisturizing Factors Responsible for Skin Hydration: Improvement and Anti-Aging of Skin by Galactomyces Ferment Filtrate-PiteraTM Containing Skin Moisturizer
4
作者 Kukizo Miyamoto Yoko Munakata +4 位作者 Keisuke Fujii Wang Summer Ley Yang Suda Sudarsana Masutaka Furue 《Journal of Cosmetics, Dermatological Sciences and Applications》 2024年第2期113-127,共15页
Background: Natural moisturizing factors (NMFs) are filaggrin-derived components in the cornified layer that are critical for maintaining healthy skin moisturization and barrier function. However, studies have reporte... Background: Natural moisturizing factors (NMFs) are filaggrin-derived components in the cornified layer that are critical for maintaining healthy skin moisturization and barrier function. However, studies have reported conflicting findings on the relationship between NMF levels and aging, while few studies have investigated this relationship clinically. To fill this research gap, we determined the levels of major NMF components such as free amino acids, pyrrolidone carboxylic acid, and urocanic acids, and individually verified their relationships with skin hydration, barrier function, age, and skin aging. Purpose: The objective of this study was to clinically investigate the relationship between NMF components levels and skin aging in facial skin. The main NMF components were obtained from facial skin and quantified. We then selected NMF components showing strong relationships to skin hydration, and analyzed the relationships of the levels of these selected NMF components with signs of skin aging, namely, texture, pores, wrinkles, and dullness (L-value). We also examined the efficacy of treatment with a skin care formula (SK-II Facial Treatment Essence, called SK-II FTE hereafter) including Galactomyces ferment filtrate (GFF, PiteraTM) on the selected NMF component levels associated with skin hydration and barrier function, and the signs of skin aging of texture, pores, wrinkles, and dullness (L-value). Method: We conducted two clinical trials in this research. In Study 1, we measured 23 NMF components using tape-stripped cornified layer to quantify them via an HPLC method in 196 Asian females aged 20 to 59 (mean S.D., 38.6 9.4). Facial visual aging parameters [texture, pores, wrinkles, and dullness (L-value)], as well as elasticity (R7), skin hydration, and TEWL, were quantified using facial skin imaging and skin physical property measurement devices. Study 2 was performed to evaluate whether the facial application of SK-II FTE affects the NMF levels and skin aging parameters in 63 Asian female volunteers aged 20 to 55 (38.4 9.03). During the course of Study 2, 0.6 mL of SK-II FTE was applied to the face twice daily in the morning and afternoon. Skin measurements were performed at the start of the day (baseline) and at week 8. Results: In Study 1, we examined the stratum corneum levels of 23 NMF components comparing to the skin hydration status in 196 female subjects. The subjects were divided into two groups using the median of each measured NMF component. Skin hydration values were compared between the two groups defined for each NMF component. The results showed that subjects with higher levels of six amino acids, alanine, arginine, asparagine, glutamine, glycine, and histidine, exhibited significantly higher skin hydration than those with lower amino acid levels. No significant differences in skin hydration values were found for the other 17 NMF components. We then analyzed whether the sum of these six amino acid NMF components (called 6-AA-NMFs, hereafter) is affected by aging. The 6-AA-NMF level peaked in the subjects aged 25-29, and then gradually and significantly decreased with age. Interestingly, the 6-AA-NMF level was significantly correlated with the skin hydration value, but not with TEWL. In addition, the 6-AA-NMF level demonstrated significant correlations with the signs of skin aging of texture, pores, wrinkles, and dullness (L-value). Then, in Study 2, we examined whether the daily application of SK-II FTE affects the 6-AA-NMF level and visual aging parameters in 63 females. SK-II FTE demonstrated significant increases of the levels of 6-AA-NMFs and each of its components associated with hydration and barrier function, and improvements of skin texture, pores, wrinkles, and dullness (L-value) during the 8 weeks of treatment of facial skin. Conclusion: These clinical studies with large numbers of subjects across a wide age range revealed that six amino acids as NMF components were highly correlated with facial skin hydration in the stratum corneum. The levels of these six NMF components were also found to decrease at ages after the 30 s and were significantly correlated with major signs of skin aging. Notably, these six NMF components (6-AA-NMFs) were increased by SK-II FTE treatment associated with improvements of skin hydration and signs of skin aging, namely, texture, pores, wrinkles, and dullness (L-value). These studies were limited by the lack of investigation of why some NMF components were not associated with skin hydration. More clinical trials examining various NMF components and their relationship with aging are anticipated. 展开更多
关键词 NMF Amino acid Visual Aging Parameter Hydration AGING Texture Pore Wrinkle Dullness Galactomyces Ferment Filtrate PiteraTM SK-II Facial Treatment Essence
下载PDF
Roles of humidity and heat treatment temperatures on YBa_2Cu_3O_(7-x) coated conductors by trifluoroacetic acid-metal organic deposition process
5
作者 Seok-Hern JANG Jun-Hyung LIM +7 位作者 Chang-Min LEE Eui-Cheol PARK Soo-Min HWANG Jun-Hyuk CHOI Jong-Hyun SHIM Jin-Hyun PARK Won KIM Jinho JOO 《中国有色金属学会会刊:英文版》 EI CSCD 2009年第4期956-960,共5页
YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition(TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure... YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition(TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure,degree of texture and critical properties of the films were evaluated.In order to understand the combined effects of the humidity and the calcining and firing temperatures on critical properties,heat-treatment was performed at various temperatures with the other processing variables fixed.The films were calcined at 400-430 ℃ and fired at 750-800 ℃ in a 0-12.1% humidified Ar-O2 atmosphere.The texture was determined by pole-figure analysis.The amount of the BaF2 phase was effectively reduced and a sharp and strong biaxial texture was formed under a humidified atmosphere,which led to increased critical properties.In addition,the microstructure varied significantly with firing temperature but changed little with calcining temperature.The highest IC of 40 A/cm-width,which corresponds to JC value of 1.8 MA/cm2,was obtained for the films fired at 775 ℃(in 12.1% humidity) after calcining at 400-430 ℃.It is likely that the highest IC value is due to the formation of a more pure YBCO phase,c-axis grains,and a denser microstructure. 展开更多
关键词 YBA2CU3O7 湿
下载PDF
A Reliable Methodology for Quantitative Extraction of Fruit and Vegetable Physiological Amino Acids and Their Subsequent Analysis with Commonly Available HPLC Systems 被引量:4
6
作者 Wayne W. Fish 《Food and Nutrition Sciences》 2012年第6期863-871,共9页
Many of the extraction and amino acid analysis methodologies currently employed do not provide complete analysis of all the physiological amino acids and biogenic amines. Extraction procedures frequently employ dilute... Many of the extraction and amino acid analysis methodologies currently employed do not provide complete analysis of all the physiological amino acids and biogenic amines. Extraction procedures frequently employ dilute acid which partially converts gln and asn to glu and asp. A commonly used pre-column derivatizing agent, o-phthalaldehyde, does not react with the imino acids, pro and hydroxypro. The purpose of this investigation was to integrate extraction and analysis procedures into a reliable method for measuring the complete physiological amino acid profiles of fruit and vegetables using HPLC instrumentation commonly available to most laboratories. Water extraction of ground, frozen-thawed tissues effected complete recovery of the physiological amino acids as demonstrated by spiking experiments and tissue combination experiments. HPLC of dabsyl derivatives of the free amino acids allowed their quantification in a selection of fruit and vegetables. Physiological amino acid levels were determined for peach, apple, potato, onion, tomato, bell pepper, broccoli, and seven types of cucurbits. The coefficient of variation for estimation of an amino acid level generally fell in the range of 5% to 7%. Because of marked variability in physiological amino acid content as a result of growing conditions, cultural practices, and inherent cultivar differences, comparisons of results with literature values were not possible. 展开更多
关键词 CITRULLUS lanatus CUCUMIS melo CUCURBITA pepo CUCUMIS sativus CUCURBITA foetidissima Brassica OLERACEA Allium cepa Prunus persica Capiscum annum SOLANUM TUBEROSUM SOLANUM lycopersicum Malus domes-tica HPLC Free Amino acids
下载PDF
MGMT is down-regulated independently of promoter DNA methylation in rats with all-trans retinoic acidinduced spina bifida aperta 被引量:2
7
作者 He-Nan Zhang Yi Guo +3 位作者 Wei Ma Jia Xue Wei-Lin Wang Zheng-Wei Yuan 《Neural Regeneration Research》 SCIE CAS CSCD 2019年第2期361-368,共8页
O6-methylguanine DNA methyltransferase(MGMT), a DNA repair enzyme, has been reported in some congenital malformations, but it is less frequently reported in neural tube defects. This study investigated MGMT mRNA expre... O6-methylguanine DNA methyltransferase(MGMT), a DNA repair enzyme, has been reported in some congenital malformations, but it is less frequently reported in neural tube defects. This study investigated MGMT mRNA expression and methylation levels in the early embryo and in different embryonic stages, as well as the relationship between MGMT and neural tube defects. Spina bifida aperta was induced in rats by a single intragastric administration of all-trans retinoic acid on embryonic day(E) 10, whereas normal control rats received the same amount of olive oil on the same embryonic day. DNA damage was assessed by detecting γ-H2 A.X in spina bifida aperta rats. Real time-polymerase chain reaction was used to examine mRNA expression of MGMT in normal control and spina bifida aperta rats. In normal controls, the MGMT mRNA expression decreased with increasing embryonic days, and was remarkably reduced from E11 to E14, reaching a minimum at E18. In the spina bifida aperta model, γ-H2 A.X protein expression was increased, and mRNA expression of MGMT was markedly decreased on E14, E16, and E18. Bisulfite sequencing polymerase chain reaction for MGMT promoter methylation demonstrated that almost all CpG sites in the MGMT promoter remained unmethylated in both spina bifida aperta rats and normal controls, and there was no significant difference in methylation level between the two groups on either E14 or E18. Our results show that DNA damage occurs in spina bifida aperta rats. The mRNA expression of MGMT is downregulated, and this downregulation is independent of promoter DNA methylation. 展开更多
关键词 nerve REGENERATION NEURAL tube defects spina bifida aperta spinal cord all-trans RETINOIC acid O6-methylguanine DNA methyltransferase gene expression DNA methylation PROMOTER BISULFITE sequencing polymerase chain reaction NEURAL REGENERATION
下载PDF
Protective actions of salvianolic acid A on hepatocyte injured by peroxidation in vitro 被引量:15
8
作者 Hu YY Liu CH +3 位作者 Wang RP Liu C Liu P Zhu DY 《World Journal of Gastroenterology》 SCIE CAS CSCD 2000年第3期402-404,共3页
INTRODUCTION Salvianolic radix,one of the most commonly usedtraditional Chinese herbs,was widely studied aboutits actions against liver injury and fibrosis,and wasone of the focuses of recent research.Salvianolic acid... INTRODUCTION Salvianolic radix,one of the most commonly usedtraditional Chinese herbs,was widely studied aboutits actions against liver injury and fibrosis,and wasone of the focuses of recent research.Salvianolic acid-A(SA-A)was an aqueous solublecomponent of Salvianolic radix.In our 展开更多
关键词 Salvianolic acid A HEPATOCYTE carbon TETRACHLORIDE liver injury lipid PEROXIDATION water soluble vitamin E ALT AST superoxide DISMUTASE malondiadehyde catalase LACTASE dehydrogenase GLUTATHIONE peroxidase GLUTATHIONE
下载PDF
Increased excitatory amino acid transporter 2 levels in basolateral amygdala astrocytes mediate chronic stress–induced anxiety-like behavior
9
作者 Xirong Xu Shoumin Xuan +3 位作者 Shuai Chen Dan Liu Qian Xiao Jie Tu 《Neural Regeneration Research》 SCIE CAS 2025年第6期1721-1734,共14页
The conventional perception of astrocytes as mere supportive cells within the brain has recently been called into question by empirical evidence, which has revealed their active involvement in regulating brain functio... The conventional perception of astrocytes as mere supportive cells within the brain has recently been called into question by empirical evidence, which has revealed their active involvement in regulating brain function and encoding behaviors associated with emotions.Specifically, astrocytes in the basolateral amygdala have been found to play a role in the modulation of anxiety-like behaviors triggered by chronic stress. Nevertheless, the precise molecular mechanisms by which basolateral amygdala astrocytes regulate chronic stress–induced anxiety-like behaviors remain to be fully elucidated. In this study, we found that in a mouse model of anxiety triggered by unpredictable chronic mild stress, the expression of excitatory amino acid transporter 2 was upregulated in the basolateral amygdala. Interestingly, our findings indicate that the targeted knockdown of excitatory amino acid transporter 2 specifically within the basolateral amygdala astrocytes was able to rescue the anxiety-like behavior in mice subjected to stress. Furthermore, we found that the overexpression of excitatory amino acid transporter 2 in the basolateral amygdala, whether achieved through intracranial administration of excitatory amino acid transporter 2agonists or through injection of excitatory amino acid transporter 2-overexpressing viruses with GfaABC1D promoters, evoked anxiety-like behavior in mice. Our single-nucleus RNA sequencing analysis further confirmed that chronic stress induced an upregulation of excitatory amino acid transporter 2 specifically in astrocytes in the basolateral amygdala. Moreover, through in vivo calcium signal recordings, we found that the frequency of calcium activity in the basolateral amygdala of mice subjected to chronic stress was higher compared with normal mice.After knocking down the expression of excitatory amino acid transporter 2 in the basolateral amygdala, the frequency of calcium activity was not significantly increased, and anxiety-like behavior was obviously mitigated. Additionally, administration of an excitatory amino acid transporter 2 inhibitor in the basolateral amygdala yielded a notable reduction in anxiety level among mice subjected to stress. These results suggest that basolateral amygdala astrocytic excitatory amino acid transporter 2 plays a role in in the regulation of unpredictable chronic mild stress-induced anxiety-like behavior by impacting the activity of local glutamatergic neurons, and targeting excitatory amino acid transporter 2 in the basolateral amygdala holds therapeutic promise for addressing anxiety disorders. 展开更多
关键词 ANXIETY ASTROCYTES basolateral amygdala behavior dihydrokainic acid excitatory amino acid transporter 2 fiber photometry GLUTAMATE LDN-212320 TRANSPORTER
下载PDF
Biochemical changes in grape rootstocks resulted from humic acid treatments in relation to nematode infection 被引量:4
10
作者 Hosny H Kesba Hossam S El-Beltagi 《Asian Pacific Journal of Tropical Biomedicine》 SCIE CAS 2012年第4期287-293,共7页
Objective:To investigate the effect of humic acid on nematode infected,resistant and susceptible grapes in relation to lipid peroxidation and antioxidant mechanisms on selected biochemical parameters known as proactiv... Objective:To investigate the effect of humic acid on nematode infected,resistant and susceptible grapes in relation to lipid peroxidation and antioxidant mechanisms on selected biochemical parameters known as proactive substances.Methods:The grape rootstocks,superior,superior/ freedom and freedom were reacted differently to Meloidogyne incognita and Rotylenchulus reniformis according to rootstock progenitor.Two weeks after inoculation,two commercial products of humic acid were applied at the rate of(2,4 mL or grams/plant) as soil drench.After 4 months,nematode soil populations were extracted and counted.A subsample of roots from each plant was stained and gall numbers,embedded stages per root were calculated,final population, nematode build up(Pf/Pi),average of eggs/eggmass were estimated.Subsamples of fresh root of each treatment were chemically analyzed.Results:Freedom reduced significantly the nematode criteria and build up.Humic acid granules appeared to be more suppressive to nematode build up on superior and the higher dose on superior/freedom than liquid treatments.On freedom,all treatments reduced significantly the nematode build up regardless to the material nature.The higher dose was more effective than the lower one.As a result of humic acid applications,the malondialdehyde(MDA) and H_2O_2 contents were significandy reduced after humic acid treatments while the antioxidant compounds glutathione(GSH),ascorbic acid(ASA) and total phenol contents were significandy increased when compared with check.Antioxidant defense enzymes ascorbate peroxidase(AFX),superoxide dismutase(SOD),catalase(CAT) and polyphenol oxidase(PPO) showed significant increase in their specific activities in treated plants compared with nematode treated check.Conclnsions:Humic acid treatments improve we yield of grape by increasing the contents of antioxidant compounds and the specific activities of antioxidant enzymes. 展开更多
关键词 MELOIDOGYNE incognita Rotylenchulus reniformis GRAPE HUMIC acid Oxidative stress ANTIOXIDANT enzymes Lipid PEROXIDATION Nematode GRAPE ROOTSTOCKS ANTIOXIDANT compounds Biochemical parameters Proactive substance MDA SOD
下载PDF
Maintaining moderate levels of hypochlorous acid promotes neural stem cell proliferation and differentiation in the recovery phase of stroke
11
作者 Lin-Yan Huang Yi-De Zhang +9 位作者 Jie Chen Hai-Di Fan Wan Wang Bin Wang Ju-Yun Ma Peng-Peng Li Hai-Wei Pu Xin-Yian Guo Jian-Gang Shen Su-Hua Qi 《Neural Regeneration Research》 SCIE CAS 2025年第3期845-857,共13页
It has been shown clinically that continuous removal of ischemia/reperfusion-induced reactive oxygen species is not conducive to the recovery of late stroke.Indeed,previous studies have shown that excessive increases ... It has been shown clinically that continuous removal of ischemia/reperfusion-induced reactive oxygen species is not conducive to the recovery of late stroke.Indeed,previous studies have shown that excessive increases in hypochlorous acid after stroke can cause severe damage to brain tissue.Our previous studies have found that a small amount of hypochlorous acid still exists in the later stage of stroke,but its specific role and mechanism are currently unclear.To simulate stroke in vivo,a middle cerebral artery occlusion rat model was established,with an oxygen-glucose deprivation/reoxygenation model established in vitro to mimic stroke.We found that in the early stage(within 24 hours)of ischemic stroke,neutrophils produced a large amount of hypochlorous acid,while in the recovery phase(10 days after stroke),microglia were activated and produced a small amount of hypochlorous acid.Further,in acute stroke in rats,hypochlorous acid production was prevented using a hypochlorous acid scavenger,taurine,or myeloperoxidase inhibitor,4-aminobenzoic acid hydrazide.Our results showed that high levels of hypochlorous acid(200μM)induced neuronal apoptosis after oxygen/glucose deprivation/reoxygenation.However,in the recovery phase of the middle cerebral artery occlusion model,a moderate level of hypochlorous acid promoted the proliferation and differentiation of neural stem cells into neurons and astrocytes.This suggests that hypochlorous acid plays different roles at different phases of cerebral ischemia/reperfusion injury.Lower levels of hypochlorous acid(5 and 100μM)promoted nuclear translocation ofβ-catenin.By transfection of single-site mutation plasmids,we found that hypochlorous acid induced chlorination of theβ-catenin tyrosine 30 residue,which promoted nuclear translocation.Altogether,our study indicates that maintaining low levels of hypochlorous acid plays a key role in the recovery of neurological function. 展开更多
关键词 cell differentiation cerebral ischemia/reperfusion injury CHLORINATION hypochlorous acid MICROGLIA neural stem cell NEUROGENESIS nuclear translocation stroke β-catenin
下载PDF
Enhanced autophagic clearance of amyloid-βvia histone deacetylase 6-mediated V-ATPase assembly and lysosomal acidification protects against Alzheimer's disease in vitro and in vivo
12
作者 Zhimin Long Chuanhua Ge +5 位作者 Yueyang Zhao Yuanjie Liu Qinghua Zeng Qing Tang Zhifang Dong Guiqiong He 《Neural Regeneration Research》 SCIE CAS 2025年第9期2633-2644,共12页
Recent studies have suggested that abnormal acidification of lysosomes induces autophagic accumulation of amyloid-βin neurons,which is a key step in senile plaque formation.Therefore,resto ring normal lysosomal funct... Recent studies have suggested that abnormal acidification of lysosomes induces autophagic accumulation of amyloid-βin neurons,which is a key step in senile plaque formation.Therefore,resto ring normal lysosomal function and rebalancing lysosomal acidification in neurons in the brain may be a new treatment strategy for Alzheimer's disease.Microtubule acetylation/deacetylation plays a central role in lysosomal acidification.Here,we show that inhibiting the classic microtubule deacetylase histone deacetylase 6 with an histone deacetylase 6 shRNA or thehistone deacetylase 6 inhibitor valproic acid promoted lysosomal reacidification by modulating V-ATPase assembly in Alzheimer's disease.Fu rthermore,we found that treatment with valproic acid markedly enhanced autophagy.promoted clearance of amyloid-βaggregates,and ameliorated cognitive deficits in a mouse model of Alzheimer's disease.Our findings demonstrate a previously unknown neuroprotective mechanism in Alzheimer's disease,in which histone deacetylase 6 inhibition by valproic acid increases V-ATPase assembly and lysosomal acidification. 展开更多
关键词 Alzheimer's disease amyloid-β APP/PS1 mice autophagy cognitive impairment histone deacetylase 6 lysosomal acidification microtubule acetylation valproic acid V-ATPASE
下载PDF
Actional Mechanism of Trifluoroacetic Acid for the Separation of Biopolymers by Reversed-phase Liquid Chromatography
13
作者 SHI Ya-li and GENG Xin-du (Department of Chemistry, Northwest University, Xi’an, 710069) 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 1992年第3期207-211,共5页
The present paper covers the actional mechanism of trifluoroacetic acid for the separation of biopolymers investigated by using the parameters of stoichiometric displacement model for retention(SDM-R) in reversed-phas... The present paper covers the actional mechanism of trifluoroacetic acid for the separation of biopolymers investigated by using the parameters of stoichiometric displacement model for retention(SDM-R) in reversed-phase liquid chromatography. It was found that the trifluoroacetic acid(TFA) may participate in, or stimulate the association among displacing agent molecules in mobile phase, and decrease the affinity of both the associate molecules of the displacing agent and the TFA-protein ion-pairing. The former dominates over the separation selectivity of biopolymers as the concentration of TFA is lower than a given value, and the two contrary functions partly offset to each other and the latter dominates as its concentration is greater than the given value. 展开更多
关键词 trifluoroacetic acid Actional mechanism Reversed-phase liquid chroma-tography SEPARATION Biopolymers
下载PDF
Effects of glycyrrhetinic acid on collagen metabolism of hepatic stellate cells at different stages of liver fibrosis in rats 被引量:29
14
作者 Ji Yao Wang Qi Sheng Zhang +1 位作者 Ji Sheng Guo Mei Yu Hu Department of Gastroenterology, Zhongshan Hospital, Medical Center, Fu Dan University Shanghai Medical University), Shanghai 200032, China 《World Journal of Gastroenterology》 SCIE CAS CSCD 2001年第1期115-119,共5页
INTRODUCTIONLiver fibrosis is a dynamic course leading tocirrhosis from a various chronic liver diseases. Thepathological basis of fibrosis is the disturbance ofproduction and degradation of the extracellularmatrix (E... INTRODUCTIONLiver fibrosis is a dynamic course leading tocirrhosis from a various chronic liver diseases. Thepathological basis of fibrosis is the disturbance ofproduction and degradation of the extracellularmatrix (ECM), which causes accumulation of ECMin the liver[1,2]. 展开更多
关键词 Administration Topical Animals Anti-Inflammatory Agents Carbon Tetrachloride Cell Division Collagen Type I Collagen Type III COLLAGENASES Disease Models Animal Gene Expression Glycyrrhetinic acid Liver Cirrhosis Plasmids PROCOLLAGEN PROLINE RNA Messenger RATS Rats Sprague-Dawley Research Support Non-U.S. Gov't THYMIDINE Tritium
下载PDF
Methylmalonic Acidemia: An Unusual Cause of Chronic Renal Disease in Adults
15
作者 Kamel El Reshaid Abdulrahman Al Kanderi 《Open Journal of Nephrology》 2024年第3期334-339,共6页
Background: Methylmalonic aciduria (MMA) is a genetic disorder of aminoacid metabolism, due to mutations in methylmalonyl-CoA mutase, which leads to the accumulation of methylmalonic acid in body fluids. Patients typi... Background: Methylmalonic aciduria (MMA) is a genetic disorder of aminoacid metabolism, due to mutations in methylmalonyl-CoA mutase, which leads to the accumulation of methylmalonic acid in body fluids. Patients typically present at the age of 1 month to 1 year with dehydration, renal impairment as well as neurologic manifestations viz. seizure, encephalopathy, strokes and disease in the globus pallidi. The case: a 26-year-old man presented with severe acute on top of chronic renal disease with serum creatinine at 590 umol/L and bilateral 8 cm kidneys with thin and echogenic cortex. He had: (a) hypernatremic dehydration, metabolic acidosis and high ammonia level with (b) a history of multiple similar attacks since the age of 8 months. Diagnosis of MMA was confirmed by high serum and urine enzymatic levels as well as genetic testing. His initial management included support with replacements of fluids, electrolytes, and bicarbonates as well as intravenous dextrose, vitamin B12 and broad-spectrum antibiotic (Meropenem) for his chest infection. Subsequently, he received 1) CARBAGLU (carglumic acid) for 7 days to lower his ammonia level to Conclusion: Untreated homozygous MMA variants, can achieve adulthood with significant renal disease yet their morbidity and mortality can be ameliorated with diet and specific therapy. 展开更多
关键词 Methylmalonic acidemia Kidney Failure Metabolic acidosis Autosomal Recessive Amino acid Disorder Kreps Cycle Hyperammonia Vitamin 12 CARNITINE
下载PDF
马铃薯疮痂病菌Streptomyces acidiscabies鉴定及抑菌有机酸筛选
16
作者 黄勋 丰加文 +6 位作者 何文睿 徐亚锦 邓琳梅 周昆燕 张潇方 杨艳丽 刘霞 《中国农学通报》 2024年第18期125-134,共10页
本研究旨在鉴定微型薯连作基质中疮痂病原菌的种类,筛选具有良好抑制活性的有机酸以利于控制疮痂病发生。研究从病薯上分离纯化病原菌,用薯片法、萝卜片法及温室盆栽接种法检测其致病性,结合形态学观察、生理生化特性测定及16S rRNA基... 本研究旨在鉴定微型薯连作基质中疮痂病原菌的种类,筛选具有良好抑制活性的有机酸以利于控制疮痂病发生。研究从病薯上分离纯化病原菌,用薯片法、萝卜片法及温室盆栽接种法检测其致病性,结合形态学观察、生理生化特性测定及16S rRNA基因序列分析确定种类,对其耐盐性等生物学特性进行研究,用纸碟法测定甲酸等有机酸对疮痂链霉菌生长的影响。链霉菌19311具有致病性,其致病岛毒力相关基因型为txtAB+/tomA+/necI+,根据19311菌株培养特征、生理生化特性及16S rRNA序列分析结果鉴定为酸性疮痂链霉菌(Streptomyces acidiscabies)。甲酸、乙酸、丙酸、乳酸、柠檬酸、酒石酸可显著抑制S.acidiscabies的生长,甲酸抑菌效果最佳,抑菌圈直径为45.43 mm,抑菌最低有效浓度为1%,可通过增加细胞膜通透性抑制S.acidiscabies生长。综上所述,本研究明确了微型薯生产基质中疮痂链霉菌19311的种类及其生物学特性。未来可考虑使用1%甲酸进行疮痂病的控制试验,并评估其对原原种生产的潜在影响。 展开更多
关键词
下载PDF
Decoding the nexus:branched-chain amino acids and their connection with sleep,circadian rhythms,and cardiometabolic health
17
作者 Hui Li Laurent Seugnet 《Neural Regeneration Research》 SCIE CAS 2025年第5期1350-1363,共14页
The sleep-wake cycle stands as an integrative process essential for sustaining optimal brain function and,either directly or indirectly,overall body health,encompassing metabolic and cardiovascular well-being.Given th... The sleep-wake cycle stands as an integrative process essential for sustaining optimal brain function and,either directly or indirectly,overall body health,encompassing metabolic and cardiovascular well-being.Given the heightened metabolic activity of the brain,there exists a considerable demand for nutrients in comparison to other organs.Among these,the branched-chain amino acids,comprising leucine,isoleucine,and valine,display distinctive significance,from their contribution to protein structure to their involvement in overall metabolism,especially in cerebral processes.Among the first amino acids that are released into circulation post-food intake,branched-chain amino acids assume a pivotal role in the regulation of protein synthesis,modulating insulin secretion and the amino acid sensing pathway of target of rapamycin.Branched-chain amino acids are key players in influencing the brain's uptake of monoamine precursors,competing for a shared transporter.Beyond their involvement in protein synthesis,these amino acids contribute to the metabolic cycles ofγ-aminobutyric acid and glutamate,as well as energy metabolism.Notably,they impact GABAergic neurons and the excitation/inhibition balance.The rhythmicity of branchedchain amino acids in plasma concentrations,observed over a 24-hour cycle and conserved in rodent models,is under circadian clock control.The mechanisms underlying those rhythms and the physiological consequences of their disruption are not fully understood.Disturbed sleep,obesity,diabetes,and cardiovascular diseases can elevate branched-chain amino acid concentrations or modify their oscillatory dynamics.The mechanisms driving these effects are currently the focal point of ongoing research efforts,since normalizing branched-chain amino acid levels has the ability to alleviate the severity of these pathologies.In this context,the Drosophila model,though underutilized,holds promise in shedding new light on these mechanisms.Initial findings indicate its potential to introduce novel concepts,particularly in elucidating the intricate connections between the circadian clock,sleep/wake,and metabolism.Consequently,the use and transport of branched-chain amino acids emerge as critical components and orchestrators in the web of interactions across multiple organs throughout the sleep/wake cycle.They could represent one of the so far elusive mechanisms connecting sleep patterns to metabolic and cardiovascular health,paving the way for potential therapeutic interventions. 展开更多
关键词 branched-chain amino acids cardiovascular health circadian clock DROSOPHILA INSULIN metabolism SLEEP γ-aminobutyric acid
下载PDF
Short term effect of Salvia miltiorrhiza in treating rat acetic acid chronic gastric ulcer and long term effect in preventing recurrence 被引量:8
18
作者 Wang, GZ Ru, X +1 位作者 Ding, LH Li, HQ 《World Journal of Gastroenterology》 SCIE CAS CSCD 1998年第2期77-78,共2页
AIM To study the short term effect of Danshen ( Salvia miltiorrhiza ) on acetic acid induced chronic gastric ulcer in rats and its long term effect in preventing recurrence. METHODS Rats with acetic acid indu... AIM To study the short term effect of Danshen ( Salvia miltiorrhiza ) on acetic acid induced chronic gastric ulcer in rats and its long term effect in preventing recurrence. METHODS Rats with acetic acid induced gastric ulcer were treated with Danshen and cimetidine for 30 days. Traditional gastric mucosal auto radiography and 3H TdR incorporation into gastric mucosa in vitro were employed to study the effects of Danshen in rat acetic acid induced chronic gastric ulcer, including ulcer index (UI), ulcer inhibitory rate (IR) and label rate (LR). RESULTS On the day 5, 30 and 126 of ulcer making, the UI in the Danshen group was obviously lower than that in the cimetidine group and the control group (42 3±3 9, 3 6±1 2, 4 4±2 3; 49 1±3 6, 5 9±1 4, 9 2±1 3; 61 0±3 8, 8 9±2 5, 12 4±2 4, respectively, P <0 01), the IR (%) in the Danshen group was obviously higher than that in the cimetidine group (31, 59, 64 8; 19, 33, 26, respectively), and the LR in the Danshen group was obviously higher than that in the cimetidine group and the control group (10 0±0 5, 16 2±0 8, 15 0±0 6; 9 0±0 5, 13 9±0 6, 10 8±0 7; 6 5±0 7, 10 1±0 5, 8 0±0 7, respectively, P <0 01). There was no obvious difference in UI in the Danshen group on day 30 as compared with that on day 126. CONCLUSION Danshen is effective in promoting ulcer healing and preventing recurrence. The mechanism of action is to strengthen the gastric mucosal barrier and to promote the gastric mucosal cell proliferation along the edge of the ulcer. 展开更多
关键词 DANSHEN disease models animal SALVIA miltiorrhiza stomach ulcer acetic acid cimitidine gastric MUCOSA RECURRENCE rats Wistar chronic diseases
下载PDF
An Approach for Using of Poly Glycolic Acid (PGA) in Reference Standard Dosimetry: PGA/ESR Dosimetry System Response Curve and Post Irradiation Stability
19
作者 Arbi Mejri Haikel Jelassi +2 位作者 Khaled Farah Ahmad Hichem Hamzaoui Hichem Eleuch 《World Journal of Nuclear Science and Technology》 2012年第3期73-79,共7页
Reference Standard Dosimeters are used to calibrate radiation environments and routine dosimeters. It can also be used in routine dosimetry applications for radiation processing where higher quality dosimetry measurem... Reference Standard Dosimeters are used to calibrate radiation environments and routine dosimeters. It can also be used in routine dosimetry applications for radiation processing where higher quality dosimetry measurements are required. Electron Spin Resonance (ESR) is a well-established Reference Standard Dosimetry system in industrial applications of ionising radiation, and its use is also proposed in radiation therapy and accident dosimetry. In the present experimental work, PGA solid state dosimeter (SSD) has been investigated using ESR spectroscopy to study the gamma radiation response of this material and to evaluate its dosimetric characteristics: dose response, room temperature fading, heat treatment effect during post-irradiation storage. Results obtained up to now confirm that PGA seems to be suitable material for ESR dosimetry applications. 展开更多
关键词 DOSIMETRY Solid State Dosimeter (SSD) POLY Glycolic acid (PGA) Electron Spin Resonance (ESR) Reference Standard Dosimetery Post-Irradiation Thermal Treatments Fading Behaviour
下载PDF
一种新型2,6-吡啶二甲酸镓(Ⅲ)配合物的合成、结构及抑菌活性研究(英文) 被引量:3
20
作者 张秀英 李书静 杨林 《无机化学学报》 SCIE CAS CSCD 北大核心 2005年第7期1109-1114,共6页
关键词 crystal Infrared Bacillus spectra complex the and space group check The with acid unit cell was its met ^1H NMR for to
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部