WorldWideScience

Sample records for exogenously applied ascorbic

  1. Exogenous ascorbic acid improves defence responses of sunflower (Helianthus annuus) exposed to multiple stresses.

    Science.gov (United States)

    Kaya, Armagan

    2017-09-01

    Ascorbic acid is an important antioxidant that plays role both on growth and development and also stress response of the plant. The purpose of this study was to determine the effect of ascorbate on physiological and biochemical changes of sunflower that was exposed to multiple stresses. Chlorophyll and carotenoid contents decreased and glutathione, ascorbate and malondialdehyde contents as well as antioxidant enzyme activities increased for sunflower plant that was exposed to 50 mM NaCl and pendimethalin at different concentrations. These changes were found to be more significant in groups simultaneously exposed to both stress factors. While malondialdehyde content decreased, chlorophyll, carotenoid, ascorbate, glutathione contents and antioxidant enzyme activities increased in plants treated exogenously with ascorbate, compared to the untreated samples. According to the findings of our study; compared to individual stress, the effect of stress is more pronounced in sunflower exposed to multiple stresses, and treatment with exogenous ascorbate reduces the negative effects of stress.

  2. Exogenous ascorbic acid increases resistance to salt of Silybum ...

    African Journals Online (AJOL)

    However, irrigation with salt water enhanced carotenoids and antioxidant enzyme activities. The detrimental effects of salt water were ameliorated by application of 100 ppm ascorbic acid (vitamin C). The inductive role of vitamin was associated with the improvement of seed germination, growth, plant water status, ...

  3. Exogenous application of ascorbic acid alleviates chilling injury in apricot (Prunus armeniaca L. cv. Shahroudi flowers

    Directory of Open Access Journals (Sweden)

    Hassan Bayat

    2013-08-01

    Full Text Available One of the most important limiting factors in spread of apricot in Iran is late spring frost, which damages flower bud and decrease total yield of crop. It has been found that ascorbic acid (AA plays a beneficial role during plant response to chilling and freezing stresses. To evaluate the effects of AA on alleviating of cold stress, the flower buds of Prunus armeniaca L. cv. Shahroudi were sprayed at pink cluster stage with AS at 4 levels (0, 100, 200 and 300 mg. L-1 and were then exposed to artificial cold stress (4 h at –4 °C or without cold stress (+ 25°C. Experimental attributes including electrolyte leakage (EL of flower buds and percentage of damage of pistil, anthers and petals to temperature treatments were determined. The results showed that at - 4°C the lowest and highest percentage of damage and EL of flower buds were observed in application of 200 and 0 mg. L-1 AA, respectively. The highest and lowest percentage of damage of flower organs and EL were obtained in application of 300 and 200 mg. L-1 AA, respectively at + 25 °C. Based on the results of this experiment, AA alleviates the negative effect of cold stress on EL and flower organ damages in apricot cv. Shahroudi, depending on the concentrations of AA used.

  4. Exogenous Spermidine Alleviates Low Temperature Injury in Mung Bean (Vigna radiata L. Seedlings by Modulating Ascorbate-Glutathione and Glyoxalase Pathway

    Directory of Open Access Journals (Sweden)

    Kamrun Nahar

    2015-12-01

    Full Text Available The role of exogenous spermidine (Spd in alleviating low temperature (LT stress in mung bean (Vigna radiata L. cv. BARI Mung-3 seedlings has been investigated. Low temperature stress modulated the non-enzymatic and enzymatic components of ascorbate-glutathione (AsA-GSH cycle, increased H2O2 content and lipid peroxidation, which indicate oxidative damage of seedlings. Low temperature reduced the leaf relative water content (RWC and destroyed leaf chlorophyll, which inhibited seedlings growth. Exogenous pretreatment of Spd in LT-affected seedlings significantly increased the contents of non-enzymatic antioxidants of AsA-GSH cycle, which include AsA and GSH. Exogenous Spd decreased dehydroascorbate (DHA, increased AsA/DHA ratio, decreased glutathione disulfide (GSSG and increased GSH/GSSG ratio under LT stress. Activities of AsA-GSH cycle enzymes such as ascorbate peroxidase (APX, monodehydroascorbate reductase (MDHAR, dehydroascorbate reductase (DHAR and glutathione reductase (GR increased after Spd pretreatment in LT affected seedlings. Thus, the oxidative stress was reduced. Protective effects of Spd are also reflected from reduction of methylglyoxal (MG toxicity by improving glyoxalase cycle components, and by maintaining osmoregulation, water status and improved seedlings growth. The present study reveals the vital roles of AsA-GSH and glyoxalase cycle in alleviating LT injury.

  5. Responses of Rapid Viscoanalyzer Profile and Other Rice Grain Qualities to Exogenously Applied Plant Growth Regulators under High Day and High Night Temperatures.

    Directory of Open Access Journals (Sweden)

    Shah Fahad

    Full Text Available High-temperature stress degrades the grain quality of rice; nevertheless, the exogenous application of plant growth regulators (PGRs might alleviate the negative effects of high temperatures. In the present study, we investigated the responses of rice grain quality to exogenously applied PGRs under high day temperatures (HDT and high night temperatures (HNT under controlled conditions. Four different combinations of ascorbic acid (Vc, alpha-tocopherol (Ve, brassinosteroids (Br, methyl jasmonates (MeJA and triazoles (Tr were exogenously applied to two rice cultivars (IR-64 and Huanghuazhan prior to the high-temperature treatment. A Nothing applied Control (NAC was included for comparison. The results demonstrated that high-temperature stress was detrimental for grain appearance and milling qualities and that both HDT and HNT reduced the grain length, grain width, grain area, head rice percentage and milled rice percentage but increased the chalkiness percentage and percent area of endosperm chalkiness in both cultivars compared with ambient temperature (AT. Significantly higher grain breakdown, set back, consistence viscosity and gelatinization temperature, and significantly lower peak, trough and final viscosities were observed under high-temperature stress compared with AT. Thus, HNT was more devastating for grain quality than HDT. The exogenous application of PGRs ameliorated the adverse effects of high temperature in both rice cultivars, and Vc+Ve+MejA+Br was the best combination for both cultivars under high temperature stress.

  6. Exogenously applied plant growth regulators enhance the morpho-physiological growth and yield of rice under high temperature

    Directory of Open Access Journals (Sweden)

    Shah Fahad

    2016-08-01

    Full Text Available A two-year experiment was conducted to ascertain the effects of exogenously applied plant growth regulators (PGR on rice growth and yield attributes under high day (HDT and high night temperature (HNT. Two rice cultivars (IR-64 and Huanghuazhan were subjected to temperature treatments in controlled growth chambers and four different combinations of ascorbic acid (Vc, alpha-tocopherol (Ve, brassinosteroids (Br, methyl jasmonates (MeJA and triazoles (Tr were applied. High temperature severely affected rice morphology, and also reduced leaf area, above- and below-ground biomass, photosynthesis, and water use efficiency, while increased the leaf water potential of both rice cultivars. Grain yield and its related attributes except number of panicles, were reduced under high temperature. The HDT posed more negative effects on rice physiological attributes, while HNT was more detrimental for grain formation and yield. The Huanghuazhan performed better than IR-64 under high temperature stress with better growth and higher grain yield. Exogenous application of PGRs was helpful in alleviating the adverse effects of high temperature. Among PGR combinations, the Vc+Ve+MejA+Br was the most effective treatment for both cultivars under high temperature stress. The highest grain production by Vc+Ve+MejA+Br treated plants was due to enhanced photosynthesis, spikelet fertility and grain filling, which compensated the adversities of high temperature stress. Taken together, these results will be of worth for further understanding the adaptation and survival mechanisms of rice to high temperature and will assist in developing heat-resistant rice germplasm in future.

  7. Leaves Of Cut Rose Flower Convert Exogenously Applied Glucose To Sucrose And Translocate It To Petals

    Directory of Open Access Journals (Sweden)

    Horibe Takanori

    2014-12-01

    Full Text Available To understand the role that the leaves play in the translocation of soluble carbohydrates in cut rose flowers, we first evaluated the effect of leaf removal on flower quality and the sugar content in petals. Cut rose flowers with leaves had higher soluble sugar content in petals compared with cut flower without leaves. Next, we treated cut flowers with radioactive glucose to clarify translocation routes of exogenously applied sugar. There was no significant difference between the specific radioactivity of sucrose and glucose in leaves, but specific radioactivity of sucrose in petals was much higher than that of glucose. These results suggested that most of the exogenously applied glucose first moved to the leaves, where it was converted into sucrose and then the synthesised sucrose was translocated to the petals. Our results showed that the leaves of cut rose flowers play an important role in the metabolism and transportation of exogenously applied soluble carbohydrates toward the petals, thus contributing to sustaining the post-harvest quality.

  8. Ascorbic Acid

    Science.gov (United States)

    Ascorbic acid is used to prevent and treat scurvy, a disease caused by a lack of vitamin C in ... Ascorbic acid comes in extended-release (long-acting) capsules and tablets, lozenges, syrup, chewable tablets, and liquid drops to ...

  9. Serotonergic transmission at Merkel discs: modulation by exogenously applied chemical messengers and involvement of Ih currents.

    Science.gov (United States)

    Chang, Weipang; Kanda, Hirosato; Ikeda, Ryo; Ling, Jennifer; Gu, Jianguo G

    2017-05-01

    The Merkel disc is a main type of tactile end organ consisting of Merkel cells and Aβ-afferent endings that responds to tactile stimulation with slowly adapting type 1 (SA1) afferent impulses. Our recent study has shown that Merkel discs in whisker hair follicles are serotonergic synapses using endogenous serotonin to transmit tactile signals from Merkel cells to Aβ-afferent endings. In this study, we hypothesize that tactile sensitivity of Merkel discs can be modulated by chemical messengers. We tested this hypothesis by determining whether and how SA1 responses of mouse whisker hair follicles may be affected by exogenously applied chemical messengers. We found that SA1 responses were potentiated by serotonin at low concentration (10 μM) but almost completely occluded by serotonin at high concentration (2 mM). In contrast, SA1 responses were not significantly affected by ATP and its metabolically stable analog α,β-methylene-ATP, glutamate, γ-aminobutyric acid (GABA), and histamine. SA1 responses were also not affected by antagonists for P2X receptors, ionotropic glutamate receptors, and ionotropic GABA and glycine receptors. Whole-cell patch-clamp recordings reconfirm the presence of both ionotropic and metabotropic 5-HT receptors on afferent neurons and their terminals innervating whisker hair follicles. All whisker afferent neurons expressed hyperpolarization-activated inward currents (I h ), which are potentiated by serotonin through the activation of metabotropic 5-HT receptors. Taken together, the findings substantiate the serotonergic mechanism of tactile transmission at Merkel discs and identify the involvement of I h currents in postsynaptic excitatory actions of serotonin. In addition, the findings do not favor any significant involvement of ATP, glutamate, histamine, GABA, or glycine in tactile transmission at the Merkel discs of whisker hair follicles. © 2017 International Society for Neurochemistry.

  10. Exogenously applied abscisic acid to Yan73 (V. vinifera) grapes enhances phenolic content and antioxidant capacity of its wine.

    Science.gov (United States)

    Xi, Zhu-Mei; Meng, Jiang-Fei; Huo, Shan-Shan; Luan, Li-Ying; Ma, Li-Na; Zhang, Zhen-Wen

    2013-06-01

    Yan73 is a 'teinturier' red wine variety cultivated in China and widely used in winemaking to strengthen red wine colour. The objective of this study was to evaluate the effect of exogenous abscisic acid (ABA) applied to the grapevine cluster on the antioxidant capacity and phenolic content of the wine made from Yan73. Two hundred mg/l ABA was applied on Yan73 grapevine cluster during veraison. As they mature, these ABA-treated and untreated grape berries were transformed into wines, respectively, and the phenolic content and antioxidant capacity of these wines were compared. The results showed that phenolic content (total phenolics, tannins, flavonoids and anthocyanins) and antioxidant capacity were higher in the wine produced with ABA-treated Yan73 grapes than those in the wine from untreated grapes. Compared to Cabernet Sauvignon wine, Yan73 wine had higher phenolic content and stronger antioxidant capacity. These strongly suggest that exogenously applied ABA to Yan73 grapes can enhance phenolic content and antioxidant capacity of its wine, and Yan73 wine has the higher utilization value and potential for development.

  11. The role of topically applied L-ascorbic acid in ex-vivo examination of burn-injured human skin

    Science.gov (United States)

    Pielesz, Anna; Biniaś, Dorota; Bobiński, Rafał; Sarna, Ewa; Paluch, Jadwiga; Waksmańska, Wioletta

    2017-10-01

    Wound treatment and healing is complex and is comprised of an elaborate set of processes including cellular, spectroscopic and biochemical ones as well as the ;reaction; of local tissue to thermal injury. Vitamin C as L-ascorbic acid (LA) prevents injurious effects of oxidants because it reduces reactive oxygen species to stable molecules, it becomes oxidized to the short-lived ascorbyl radical. As a result, antioxidant treatment may contribute to minimizing injury in burn patients. The aim of this study is to assess changes in molecular structure of collagen extracted from human epidermis burn wound scab during incubation of the epidermis in L-ascorbic acid solution. The study will be performed using FTIR and FT Raman spectroscopies. During this research it was observed that the intensity of Raman peaks increased where healing was being modified by LA. The intensity of the amide III band at 1247 cm- 1 relative to the intensity at 1326 cm- 1 was used to test tissue repair degree at the incision site. FTIR spectra were recorded from frozen specimens of serum modified by LA; an analysis of shifts in the amide I band position was conducted. The appearance of a new band for frozen samples modified by LA was observed around 1149-1220 cm- 1. The above conclusions confirmed the creation of hydrogen bonds between Nsbnd H stretch and Cdbnd O. Samples being incubated in solutions of L-ascorbic acid demonstrated the absence of electrophoretic bands of albumin. Alterations in the surface of the skin incubated in L-ascorbic acid were investigated with the use of Scanning Electron Microscopy (SEM). A decrease in external symptoms of burn injury was noted in the damaged epidermis incubated in L-ascorbic acid.

  12. An evaluation of the antiaging properties of strawberry hydrolysate treatment enriched with L-ascorbic acid applied with microneedle mesotherapy.

    Science.gov (United States)

    Markiewicz, Agata; Zasada, Malwina; Erkiert-Polguj, Anna; Wieckowska-Szakiel, Marzena; Budzisz, Elzbieta

    2018-04-16

    Mature skin is characterized by a loss of elasticity, hyperpigmentation, and dehydration. L-ascorbic acid stimulates the synthesis of collagen type I, inhibits melanogenesis, and helps to maintain correct skin hydration. Combining microneedle mesotherapy with the application of preparations rich in vitamin C results in better therapeutic effects due to the improved absorption of active substances. The study evaluates the effectiveness of the application of strawberry hydrolysate enriched with L-ascorbic acid using microneedle mesotherapy. Seventeen volunteers aged 45-70 years underwent a series of four microneedle mesotherapy treatments with vitamin C serum, performed every 10 days. The 20% L-ascorbic acid solution (pH = 3.5) was prepared immediately before application. After the treatment, the participants gave a subjective assessment of the effectiveness. Cutometer ® was used to measure skin elasticity and firmness, Corneometer ® to measure skin hydration, and Mexameter ® skin tone. The results of the survey showed improvements in skin hydration and elasticity. In vivo studies confirmed the effectiveness of serum and the impact of the active substance on skin firmness and elasticity, the degree of hydration and skin tone. Microneedling with vitamin C improves skin tone, hydratation and firmness, and decreases the visibility of hyperpigmentation. © 2018 Wiley Periodicals, Inc.

  13. Modulatory Effects of Exogenously Applied Polyamines on Postharvest Physiology, Antioxidant System and Shelf Life of Fruits: A Review.

    Science.gov (United States)

    Sharma, Sunil; Pareek, Sunil; Sagar, Narashans Alok; Valero, Daniel; Serrano, Maria

    2017-08-17

    Polyamines (PAs) are natural compounds involved in many growth and developmental processes in plants, and, specifically in fruits, play a vital role regulating its development, ripening and senescence processes. Putrescine (PUT), spermine (SPE), and spermidine (SPD) are prominent PAs applied exogenously to extend shelf life of fruits. They also originate endogenously during developmental phases of horticultural crops and simultaneously affect the quality attributes and shelf life. Their anti-ethylene nature is being exploited to enhance the shelf life when exogenously applied on fruits. In growth and development of fruits, PA levels generally fall, which marks the beginning of senescence at postharvest phase. PUT, SPE and SPD treatments are being applied during postharvest phase to prolong the shelf life. They enhance the shelf life of fruits by reducing respiration rate, ethylene release and enhance firmness and quality attributes in fruits. PAs have a mitigating impact on biotic and abiotic stresses including chilling injury (CI) in tropical and sub-tropical fruits. PAs are environment friendly in nature and are biodegradable without showing any negative effect on environment. Biotechnological interventions by using chimeric gene constructs of PA encoding genes has boosted the research to develop transgenic fruits and vegetables which would possess inherent or in situ mechanism of enhanced biosynthesis of PAs at different stages of development and thereby will enhance the shelf life and quality in fruits. Internal and external quality attributes of fruits are improved by modulation of antioxidant system and by strengthening biophysical morphology of fruits by electrostatic interaction between PAs and phospholipids in the cell wall.

  14. Group I mGlu receptors potentiate synaptosomal [3H]glutamate release independently of exogenously applied arachidonic acid

    International Nuclear Information System (INIS)

    Reid, M.E.; Toms, N.J.; Bedingfield, J.S.; Roberts, P.J.

    1999-01-01

    In the current study, we have characterized group I metabotropic glutamate (mGlu) receptor enhancement of 4-aminopyridine (4AP)-evoked [ 3 H]glutamate release from rat cerebrocortical synaptosomes. The broad spectrum mGlu receptor agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid ((1S,3R)-ACPD, 10 μM) increased 4AP-evoked [ 3 H]glutamate release (143.32±2.73% control) only in the presence of exogenously applied arachidonic acid; an effect reversed by the inclusion of bovine serum albumin (BSA, fatty acid free). In contrast, the selective group I mGlu receptor agonist (S)-3,5-dihydroxyphenylglycine (DHPG) potentiated (EC 50 =1.60±0.25 μM; E max =147.61±10.96% control) 4AP-evoked [ 3 H]glutamate release, in the absence of arachidonic acid. This potentiation could be abolished by either the selective mGlu 1 receptor antagonist (R,S)-1-aminoindan-1,5-dicarboxylic acid (AIDA, 1 mM) or the selective PKC inhibitor (Ro 31-8220, 10 μM) and was BSA-insensitive. The selective mGlu 5 receptor agonist (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG, 300μM) was without effect. DHPG (100 μM) also potentiated both 30 mM and 50 mM K + -evoked [ 3 H]glutamate release (121.60±12.77% and 121.50±4.45% control, respectively). DHPG (100 μM) failed to influence both 4AP-stimulated 45 Ca 2+ influx and 50 mM K + -induced changes in synaptosomal membrane potential. Possible group I mGlu receptor suppression of tonic adenosine A 1 receptor, group II/III mGlu receptors or GABA B receptor activity is unlikely since 4AP-evoked [ 3 H]glutamate release was insensitive to the selective inhibitory receptor antagonists 8-cyclopentyl-1,3-dimethylxanthine, (R,S)-α-cyclopropyl-4-phosphonophenylglycine or CGP55845A, respectively. These data suggest an 'mGlu 1 receptor-like' receptor potentiates [ 3 H]glutamate release from cerebrocortical synaptosomes in the absence of exogenously applied arachidonic acid. This PKC dependent effect is unlikely to be via modulation of synaptosomal membrane

  15. Influence of exogenously applied abscisic acid on carotenoid content and water uptake in flowers of the tea plant (Camellia sinensis).

    Science.gov (United States)

    Baldermann, Susanne; Yang, Ziyin; Sakai, Miwa; Fleischmann, Peter; Morita, Akio; Todoroki, Yasushi; Watanabe, Naoharu

    2013-05-01

    Carotenoids are a major class of plant pigments and fulfill many functions in different organisms that either produce or consume them. Although the color of the stamina of tea (Camellia sinensis) flowers is clearly due to the presence of carotenoids, the carotenoid profile and content remain to be discovered. We investigated the carotenoid profile of tea flowers and determined changes in concentrations over the floral development. The flowers contained oxygenated xanthophylls such as neoxanthin, lutein and zeaxanthin, as well as the hydrocarbons β-carotene and α-carotene. Flowers of the tea plant contain to vegetables comparable amounts of carotenoids. The content of 9'-cis-epoxycarotenoids, which serve as abscisic acid precursors, as well as changes in concentration of abscisic acid were studied. The concentrations of carotenoids decreased whereas the abscisic acid content increased over the floral development. Exogenously applied S-abscisic acid affected water uptake, flower opening and carotenoid accumulation. In summary, this paper reports, for the first time, the carotenoid profile and content of tea flowers. The study revealed that carotenoids in tea flowers are an interesting target in respect of possible applications of tea flower extracts as well as biological functions of abscisic acid during floral development. © 2012 Society of Chemical Industry.

  16. Group I mGlu receptors potentiate synaptosomal [{sup 3}H]glutamate release independently of exogenously applied arachidonic acid

    Energy Technology Data Exchange (ETDEWEB)

    Reid, M.E.; Toms, N.J.; Bedingfield, J.S.; Roberts, P.J. [Department of Pharmacology, School of Medical Sciences, University of Bristol, University Walk, Bristol, BS8 1TD (United Kingdom)

    1999-04-01

    In the current study, we have characterized group I metabotropic glutamate (mGlu) receptor enhancement of 4-aminopyridine (4AP)-evoked [{sup 3}H]glutamate release from rat cerebrocortical synaptosomes. The broad spectrum mGlu receptor agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid ((1S,3R)-ACPD, 10 {mu}M) increased 4AP-evoked [{sup 3}H]glutamate release (143.32{+-}2.73% control) only in the presence of exogenously applied arachidonic acid; an effect reversed by the inclusion of bovine serum albumin (BSA, fatty acid free). In contrast, the selective group I mGlu receptor agonist (S)-3,5-dihydroxyphenylglycine (DHPG) potentiated (EC{sub 50}=1.60{+-}0.25 {mu}M; E{sub max}=147.61{+-}10.96% control) 4AP-evoked [{sup 3}H]glutamate release, in the absence of arachidonic acid. This potentiation could be abolished by either the selective mGlu{sub 1} receptor antagonist (R,S)-1-aminoindan-1,5-dicarboxylic acid (AIDA, 1 mM) or the selective PKC inhibitor (Ro 31-8220, 10 {mu}M) and was BSA-insensitive. The selective mGlu{sub 5} receptor agonist (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG, 300{mu}M) was without effect. DHPG (100 {mu}M) also potentiated both 30 mM and 50 mM K{sup +}-evoked [{sup 3}H]glutamate release (121.60{+-}12.77% and 121.50{+-}4.45% control, respectively). DHPG (100 {mu}M) failed to influence both 4AP-stimulated {sup 45}Ca{sup 2+} influx and 50 mM K{sup +}-induced changes in synaptosomal membrane potential. Possible group I mGlu receptor suppression of tonic adenosine A{sub 1} receptor, group II/III mGlu receptors or GABA{sub B} receptor activity is unlikely since 4AP-evoked [{sup 3}H]glutamate release was insensitive to the selective inhibitory receptor antagonists 8-cyclopentyl-1,3-dimethylxanthine, (R,S)-{alpha}-cyclopropyl-4-phosphonophenylglycine or CGP55845A, respectively. These data suggest an 'mGlu{sub 1} receptor-like' receptor potentiates [{sup 3}H]glutamate release from cerebrocortical synaptosomes in the absence of

  17. Differential sensitivity of light-harnessing photosynthetic events in wheat and sunflower to exogenously applied ionic and nanoparticulate silver.

    Science.gov (United States)

    Pardha-Saradhi, P; Shabnam, Nisha; Sharmila, P; Ganguli, Ashok K; Kim, Hyunook

    2018-03-01

    Potential impacts of inevitable leaks of silver nanoparticles (AgNPs) into environment on human beings need attention. Owing to the vitality of photosynthesis in maintaining life and ecosystem functioning, impacts of exogenously applied nanoparticulate and Ag + on photosystem (PS)II function, which governs overall photosynthesis, in wheat and sunflower were evaluated. PSII efficiency and related Chl a fluorescence kinetics of these two plants remained unaffected by AgNPs. However, Ag + caused a significant decline in the PSII activity and related fluorescence steps in wheat, but not in sunflower. Electron flow between Q A and PQ pool was found most sensitive to Ag + . Number of active reaction centers, electron transport, trapping of absorbed light for photochemistry, and performance index declined, while dissipation of absorbed light energy as heat significantly increased in wheat exposed to Ag + . Total antioxidant activity in sunflower was least affected by both Ag and AgNPs. In contrast, in the case of wheat, the antioxidant activity was declined by Ag + but not by AgNPs. Further, the amount of silver absorbed by plants exposed to Ag + was higher than that absorbed by plants exposed to AgNPs. While wheat retained majority of Ag in its roots, sunflower showed major Ag accumulation in stem. Photosynthetic events in sunflower, unlike wheat, were least affected as no detectable Ag levels was recorded in their leaves. Our findings revealed that AgNPs seemed non/less-toxic to light harnessing photosynthetic machinery of wheat, compared to Ag + . Photosynthetic events in sunflower were not affected by Ag + , either, as its translocation to leaves was restricted. Copyright © 2017. Published by Elsevier Ltd.

  18. Ascorbic Acid Alleviates Water Stress in Young Peach Trees and Improves Their Performance after Rewatering

    Directory of Open Access Journals (Sweden)

    Consuelo Penella

    2017-09-01

    Full Text Available Exogenous application of biochemicals has been found to improve water stress tolerance in herbaceous crops but there are limited studies on deciduous fruit trees. The goal of this research was to study if ascorbic acid applications could improve physiological mechanisms associated with water stress tolerance in young fruit trees. Ascorbic acid was foliarly applied at a concentration of 250 ppm to water-stressed and well-watered peach trees (control of two cultivars (‘Scarletprince’ and ‘CaroTiger’. Trees received either one or two applications, and 1 week after the second application all trees were rewatered to field capacity. Upon rewatering, CO2 assimilation and stomatal conductance of water-stressed ‘Scarletprince’ trees sprayed with ascorbic acid (one or two applications were similar to those of well-irrigated trees, but water-stressed trees that had not received ascorbic acid did not recover photosynthetical functions. Also, water status in sprayed water-stressed ‘Scarletprince’ trees was improved to values similar to control trees. On the other hand, water-stressed ‘CaroTiger’ trees needed two applications of ascorbic acid to reach values of CO2 assimilation similar to control trees but these applications did not improve their water status. In general terms, different response mechanisms to cope with water stress in presence of ascorbic acid were found in each cultivar, with ‘Scarletprince’ trees preferentially using proline as compatible solute and ‘CaroTiger’ trees relying on stomatal regulation. The application of ascorbic acid reduced cell membrane damage and increased catalase activity in water-stressed trees of both cultivars. These results suggest that foliar applications of ascorbic acid could be used as a management practice for improving water stress tolerance of young trees under suboptimal water regimes.

  19. Ascorbic Acid Alleviates Water Stress in Young Peach Trees and Improves Their Performance after Rewatering.

    Science.gov (United States)

    Penella, Consuelo; Calatayud, Ángeles; Melgar, Juan C

    2017-01-01

    Exogenous application of biochemicals has been found to improve water stress tolerance in herbaceous crops but there are limited studies on deciduous fruit trees. The goal of this research was to study if ascorbic acid applications could improve physiological mechanisms associated with water stress tolerance in young fruit trees. Ascorbic acid was foliarly applied at a concentration of 250 ppm to water-stressed and well-watered peach trees (control) of two cultivars ('Scarletprince' and 'CaroTiger'). Trees received either one or two applications, and 1 week after the second application all trees were rewatered to field capacity. Upon rewatering, CO 2 assimilation and stomatal conductance of water-stressed 'Scarletprince' trees sprayed with ascorbic acid (one or two applications) were similar to those of well-irrigated trees, but water-stressed trees that had not received ascorbic acid did not recover photosynthetical functions. Also, water status in sprayed water-stressed 'Scarletprince' trees was improved to values similar to control trees. On the other hand, water-stressed 'CaroTiger' trees needed two applications of ascorbic acid to reach values of CO 2 assimilation similar to control trees but these applications did not improve their water status. In general terms, different response mechanisms to cope with water stress in presence of ascorbic acid were found in each cultivar, with 'Scarletprince' trees preferentially using proline as compatible solute and 'CaroTiger' trees relying on stomatal regulation. The application of ascorbic acid reduced cell membrane damage and increased catalase activity in water-stressed trees of both cultivars. These results suggest that foliar applications of ascorbic acid could be used as a management practice for improving water stress tolerance of young trees under suboptimal water regimes.

  20. Exogenous deposits

    International Nuclear Information System (INIS)

    Khasanov, A.Kh.

    1988-01-01

    Exogenous deposits forming as a result of complex exogenous processes, passed under the influence of outside forces on the Earth surface. To them relate physical and chemical weathering, decomposition and decay of mineral masses, redistribution and transportation of material, forming and deposit of new minerals and ores steady on the earth surface conditions

  1. A Simple and Useful Method to Apply Exogenous NO Gas to Plant Systems: Bell Pepper Fruits as a Model.

    Science.gov (United States)

    Palma, José M; Ruiz, Carmelo; Corpas, Francisco J

    2018-01-01

    Nitric oxide (NO) is involved many physiological plant processes, including germination, growth and development of roots, flower setting and development, senescence, and fruit ripening. In the latter physiological process, NO has been reported to play an opposite role to ethylene. Thus, treatment of fruits with NO may lead to delay ripening independently of whether they are climacteric or nonclimacteric. In many cases different methods have been reported to apply NO to plant systems involving sodium nitroprusside, NONOates, DETANO, or GSNO to investigate physiological and molecular consequences. In this chapter a method to treat plant materials with NO is provided using bell pepper fruits as a model. This method is cheap, free of side effects, and easy to apply since it only requires common chemicals and tools available in any biology laboratory.

  2. Final report of the safety assessment of L-Ascorbic Acid, Calcium Ascorbate, Magnesium Ascorbate, Magnesium Ascorbyl Phosphate, Sodium Ascorbate, and Sodium Ascorbyl Phosphate as used in cosmetics.

    Science.gov (United States)

    Elmore, Amy R

    2005-01-01

    microscopic pathological effects were observed in either mice, rats, or guinea pigs in short-term studies. Male guinea pigs fed a control basal diet and given up to 250 mg Ascorbic Acid orally for 20 weeks had similar hemoglobin, blood glucose, serum iron, liver iron, and liver glycogen levels compared to control values. Male and female F344/N rats and B6C3F(1) mice were fed diets containing up to 100,000 ppm Ascorbic Acid for 13 weeks with little toxicity. Chronic Ascorbic Acid feeding studies showed toxic effects at dosages above 25 mg/kg body weight (bw) in rats and guinea pigs. Groups of male and female rats given daily doses up to 2000 mg/kg bw Ascorbic Acid for 2 years had no macro- or microscopically detectable toxic lesions. Mice given Ascorbic Acid subcutaneous and intravenous daily doses (500 to 1000 mg/kg bw) for 7 days had no changes in appetite, weight gain, and general behavior; and histological examination of various organs showed no changes. Ascorbic Acid was a photoprotectant when applied to mice and pig skin before exposure to ultraviolet (UV) radiation. The inhibition of UV-induced suppression of contact hypersensitivity was also noted. Magnesium Ascorbyl Phosphate administration immediately after exposure in hairless mice significantly delayed skin tumor formation and hyperplasia induced by chronic exposure to UV radiation. Pregnant mice and rats were given daily oral doses of Ascorbic Acid up to 1000 mg/kg bw with no indications of adult-toxic, teratogenic, or fetotoxic effects. Ascorbic Acid and Sodium Ascorbate were not genotoxic in several bacterial and mammalian test systems, consistent with the antioxidant properties of these chemicals. In the presence of certain enzyme systems or metal ions, evidence of genotoxicity was seen. The National Toxicology Program (NTP) conducted a 2-year oral carcinogenesis bioassay of Ascorbic Acid (25,000 and 50,000 ppm) in F344/N rats and B6C3F(1) mice. Ascorbic Acid was not carcinogenic in either sex of both rats and

  3. Sclerotial biomass and carotenoid yield of Penicillium sp. PT95 under oxidative growth conditions and in the presence of antioxidant ascorbic acid.

    Science.gov (United States)

    Li, X L; Cui, X H; Han, J R

    2006-09-01

    To determine the effect of oxidative stress and exogenous ascorbic acid on sclerotial biomass and carotenoid yield of Penicillium sp. PT95. In this experiment, high oxidative stress was applied by the inclusion of FeSO(4) in the growth medium and exposure to light. Low oxidative stress was applied by omitting iron from the growth medium and by incubation in the dark. Supplementation of exogenous ascorbic acid (as antioxidant) to the basal medium caused a concentration-dependent delay of sclerotial differentiation (up to 48 h), decrease of sclerotial biomass (up to 40%) and reduction of carotenoid yield (up to 91%). On the contrary, the exogenous ascorbic acid also caused a concentration-dependent decrease of lipid peroxidation in colonies of this fungus. Under high oxidative stress growth condition, the sclerotial biomass and carotenoid yield of PT95 strain in each plate culture reached 305 mg and 32.94 microg, which were 1.23 and 3.71 times higher, respectively, than those at low oxidative stress growth condition. These data prompted us to consider that in order to attain higher sclerotial biomass and pigment yield, the strain PT95 should be grown under high oxidative stress and in the absence of antioxidants. These results suggest that strain PT95 may be used for solid-state fermentation of carotenoid production under high oxidative stress growth conditions.

  4. Action of exogenous ascorbic acid on physiological quality of cowpea seeds artificially agedAção do ácido ascórbico exógeno na qualidade fisiológica de sementes de feijão de corda envelhecidas artificialmente

    Directory of Open Access Journals (Sweden)

    Jean Carlos de Araújo Brilhante

    2013-06-01

    Full Text Available The aim of this study was to evaluate the effects of pre-treatment and post-treatment with ascorbic acid in reducing the damage caused by aging in cowpea seeds, which were aged in artificial accelerated aging chamber (45°C, 99% relative humidity in the dark for 72 h and it were subjected to four treatments: T1 – non-aged seeds were not treated with ascorbic acid (AsA; T2 – non-aged seeds treated with AsA; T3 – seeds before aging were subjected to a treatment with AsA to 0.85 mM; T4 – seeds after aging were subjected to a treatment with a 0.85 mM AsA. The aging of seeds for 72 h (T2 caused significant damage in the cell membranes of cowpea seeds, as evidenced by a increase in electrolyte leakage, higher level of lipid peroxidation and a lower germination percentage, when compared with the control (T1. T4 results were like the control treatment, with a lower electrolyte leakage and lipid peroxidation, well as a higher germination percentage, when compared with T2. The exogenous application of 0.85 mM ascorbic acid in cowpea seeds after artificial aging can mitigate its detrimental effects on the membranes integrity and seed physiological quality.O objetivo desse estudo foi avaliar os efeitos do pré e pós-tratamento com ácido ascórbico na redução dos danos ocasionados pelo envelhecimento em sementes de feijão de corda, as quais foram envelhecidas em câmara de envelhecimento artificial (45 ºC, 99% U.R., no escuro por 72 h, sendo submetidas a quatro tratamentos: T1 – sementes não envelhecidas e não tratadas com ácido ascórbico (AsA; T2 – sementes envelhecidas e não tratadas com AsA; T3 – sementes que antes do envelhecimento foram submetidas a um tratamento com AsA a 0,85 mM; T4 – sementes que após o envelhecimento foram submetidas a um tratamento com AsA a 0,85 mM. O envelhecimento das sementes por 72 h (T2 provocou danos significativos nas membranas celulares das sementes de feijão de corda, como foi evidenciado pelo

  5. Exogenous Ochronosis

    Directory of Open Access Journals (Sweden)

    Prachi A Bhattar

    2015-01-01

    Full Text Available Exogenous ochronosis (EO is a cutaneous disorder characterized by blue-black pigmentation resulting as a complication of long-term application of skin-lightening creams containing hydroquinone but may also occur due to topical contact with phenol or resorcinol in dark-skinned individuals. It can also occur following the use of systemic antimalarials such as quinine. EO is clinically and histologically similar to its endogenous counterpart viz., alkaptonuria, which, however, exhibits systemic effects and is an inherited disorder. Dermoscopy and in vivo skin reflectance confocal microscopy are noninvasive in vivo diagnostic tools. It is very difficult to treat EO, a cosmetically disfiguring and troubling disorder with disappointing treatment options.

  6. Study of endogenic abscisic acids and cytokinin content in soybean crops of variable salt sensitivity as well as the effect of exogenically applied abscisic acid on Cl/sup -/ translocation. [in German

    Energy Technology Data Exchange (ETDEWEB)

    Roeb, G.

    1981-05-01

    A study of the phytohormones abscisic acid and cytokinin with respect to plant salt stress and its relationship to genetic control over endogen content. An analysis is made of the acid cytokinin content, and an investigation is made of the influence exerted by exogenic applied synthetic abscisic acid on Cl/sup -/ uptake and accumulation. 275 references, 14 figures, 11 tables.

  7. Exogenous ascorbic acid increases resistance to salt of Silybum ...

    African Journals Online (AJOL)

    DR. NJ TONUKARI

    2012-05-24

    May 24, 2012 ... associated with the improvement of seed germination, growth, plant water status, carotenoids, ..... Coping with water-deficit-application of biochemical ... induce changes in the levels of some endogenous plant hormones in.

  8. Ascorbic acid in bronchial asthma

    African Journals Online (AJOL)

    1983-04-23

    Apr 23, 1983 ... by comparing the pre-ascorbic acid results with those obtained 21/2 hours after the intravenous ... (ASO), C-reactive protein and antibodies to certain respiratory viruses. These investigations were ..... vitamin.6 However, other investigators were unable to detect any protective effects of ascorbic acid on the ...

  9. Biochemical and physiological responses of lycoris sprengeri bulblets (amaryllidaceae) to exogenously applied N-(2-Chloro-4-Pyridyl)-N1-Phenylurea (CPPU)

    International Nuclear Information System (INIS)

    Ren, Z.; Xia, Y.; Xiao, Y.; Zhang, D.; Lv, X.

    2017-01-01

    Bulblets of Lycoris sprengeri (Amaryllidaceae) were obtained by cutting. Six concentrations of N-(2-chloro-4-pyridyl)-N1-phenylurea (CPPU) solutions were sprayed on leaves from one-year-old bulblets during their green period. Fresh weight, diameter,carbohydrate content, activity of starch metabolism-related enzymes and levels of endogenous hormones of bulblets were determined. The effects of CPPU treatment on bulblet development and biochemical and physiological indices of L. sprengeri were analyzed using the determined values. The results showed that CPPU treatment at an appropriate concentration promoted the enlargement of L. sprengeri bulblets; the optimal concentration was 7.5 mg L-1. Bulblet growth showed a significant positive correlation with starch content and the activities of soluble starch synthase (SSS) and starch-bound starch synthase (GBSS). Bulblet growth showed anextremely significant positive correlation with the ratio of endogenous gibberellic acid/abscisic acid (GA/ABA). The GA/ABA ratio showed a significant positive correlation with the activities of (a+beta)-amylase and GBSS. The exogenous application of CPPU promoted the synthesis and accumulation of starch in the bulblets of L. sprengeri and the activities of starch metabolism-related enzymes; an increase in the endogenous GA/ABA ratio had a synergistic effect. (author)

  10. CITOGENETICS EFFECTS INDUCED BY THE ASCORBIC ACID TREATMENT OF LARIX DECIDUA MILL. SSP. CARPATICA AND PICEA ABIES (L. KARST

    Directory of Open Access Journals (Sweden)

    Ioana Ieremia

    2006-08-01

    Full Text Available The paper present the influence of ascorbic acid upon the mitotic division of Larix decidua Mill ssp. carpatica and Picea abies (L. Karst. The treatment is applied of two variants, germinated seed in ascorbic acid (variantAand germinated seeds in disttilate water, than treated with ascorbic acid in 3 concentrations (variant B.

  11. The response of antioxidant systems in Nostoc sphaeroides against UV-B radiation and the protective effects of exogenous antioxidants

    Science.gov (United States)

    Wang, Gaohong; Hu, Chunxiang; Li, Dunhai; Zhang, Delu; Li, Xiaoyan; Chen, Kun; Liu, Yongding

    UV radiation is one of many harmful factors found in space that are detrimental to organisms on earth in space exploration. In the present work, we examined the role of antioxidant system in Nostoc sphaeroides Kütz (Cyanobacterium) and the effects of exogenously applied antioxidant molecules on its photosynthetic rate under UV-B radiation. It was found that UV-B radiation promoted the activity of antioxidant system to protect photosystem II (PSII) and exogenously applied antioxidant: sodium nitroprusside (SNP) and N-acetylcysteine (NAC) had an obvious protection on PSII activity under UV-B radiation. The activity of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7) and content of MDA (malondialdehyde) and ASC (ascorbate) were improved by 0.5 mM and 1 mM SNP, but 0.1 mM SNP decreased the activity of antioxidant system. Addition of exogenous NAC decreased the activity of SOD, POD, CAT and the content MDA and ASC. In contrast, exogenously applied NAC increased GSH content. The results suggest that exogenous SNP and NAC may protect algae by different mechanisms: SNP may play double roles as both sources of reactive free radicals as well as ROS scavengers in mediating the protective role of PSII on algae under UV-B radiation. On the other hand, NAC functions as an antioxidant or precursor of glutathione, which could protect PSII directly from UV-B radiation.

  12. Exogenous hydrogen peroxide reversibly inhibits root gravitropism and induces horizontal curvature of primary root during grass pea germination.

    Science.gov (United States)

    Jiang, Jinglong; Su, Miao; Wang, Liyan; Jiao, Chengjin; Sun, Zhengxi; Cheng, Wei; Li, Fengmin; Wang, Chongying

    2012-04-01

    During germination in distilled water (dH(2)O) on a horizontally positioned Petri dish, emerging primary roots of grass pea (Lathyrus sativus L.) grew perpendicular to the bottom of the Petri dish, due to gravitropism. However, when germinated in exogenous hydrogen peroxide (H(2)O(2)), the primary roots grew parallel to the bottom of the Petri dish and asymmetrically, forming a horizontal curvature. Time-course experiments showed that the effect was strongest when H(2)O(2) was applied prior to the emergence of the primary root. H(2)O(2) failed to induce root curvature when applied post-germination. Dosage studies revealed that the frequency of primary root curvature was significantly enhanced with increased H(2)O(2) concentrations. This curvature could be directly counteracted by dimethylthiourea (DMTU), a scavenger of H(2)O(2), but not by diphenylene iodonium (DPI) and pyridine, inhibitors of H(2)O(2) production. Exogenous H(2)O(2) treatment caused both an increase in the activities of H(2)O(2)-scavenging enzymes [including ascorbate peroxidase (APX: EC 1.11.1.11), catalase (CAT: EC 1.11.1.6) and peroxidase (POD: EC 1.11.1.7)] and a reduction in endogenous H(2)O(2) levels and root vitality. Although grass pea seeds absorbed exogenous H(2)O(2) during seed germination, DAB staining of paraffin sections revealed that exogenous H(2)O(2) only entered the root epidermis and not inner tissues. These data indicated that exogenously applied H(2)O(2) could lead to a reversible loss of the root gravitropic response and a horizontal curvature in primary roots during radicle emergence of the seedling. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  13. Ascorbic acid: Nonradioactive extracellular space marker in canine heart

    International Nuclear Information System (INIS)

    Reil, G.H.; Frombach, R.; Kownatzki, R.; Quante, W.; Lichtlen, P.R.

    1987-01-01

    The distribution pattern of ascorbic acid and L-[ 14 C]ascorbic acid in myocardial tissue was compared with those of the classical radioactive extracellular space markers [ 3 H]-inulin, [ 3 H]sucrose, and Na 82 Br. A new polarographic techniques was developed for analogue registration of ascorbic acid concentration in coronary venous blood. The kinetic data of the markers were studied in an open-chest canine heart preparation during a constant tracer infusion of up to 9 min. Distribution volumes were calculated based on the mean transit time method of Zierler. The distribution volume of ascorbic acid as well as of L-[ 14 C]ascorbic acid in myocardial tissue agreed closely with those of [ 3 H]inulin and [ 3 H]sucrose as well as 82 Br. The obtained kinetic data confirmed that ascorbic acid exhibits the physicochemical properties of an extracellular space marker, though this compound was shown to leak slowly into myocardial cells. Favorable attributes of this indicator are its low molecular weight, high diffusibility in interstitial fluid, low binding affinity to macromolecules, and high transcapillary as well as low transplasmalemmal penetration rate. Therefore, this nonradioactive marker can be applied in a safe and simple fashion, and without untoward side effects in experimental animals as well as in patients

  14. Effect of exogenous estradiol applied at different embryonic stages on sex determination, growth, and mortality in the leopard gecko (Eublepharis macularius).

    Science.gov (United States)

    Tousignant, A; Crews, D

    1994-01-01

    Temperature-dependent sex determination (TSD) occurs in three orders of reptiles. Several studies have examined the ability of estradiol to produce female hatchlings incubated at a male-producing temperature. The results of these experiments support the idea that estradiol could be used as a powerful tool in the conservation of endangered species with TSD by manipulating hatchling sex ratios. However, these experiments have concentrated on the mechanism of determination. This experiment was designed to test the efficacy of various dosages of estradiol applied at two different stages to alter the hatchling sex ratio as well as determining the potential use of such manipulation for conservation efforts by monitoring egg mortality and hatchling growth. The leopard gecko (Eublepharis macularius) exhibits TSD and reaches reproductive maturity in less than one year, making it an excellent model for evaluating the long-term effects of estradiol. The results demonstrate that estradiol has a dose-dependent effect on the hatchling sex ratio while only high dosages applied at the later stage of development showed increased mortality. Estrogen-determined females grew at the same rate as temperature-determined females and have produced viable hatchlings. Estradiol treatment of eggs from endangered species may provide a method of insuring female offspring when the TSD pattern is unknown or equipment for controlled incubation is unavailable.

  15. Exogenous vs. Endogenous Separation

    OpenAIRE

    Ramey, Garey

    2008-01-01

    This paper assesses how various approaches to modelling the separation margin a¤ect the ability of the Mortensen-Pissarides job matching model to explain key facts about the aggregate labor market. Allowing for realistic time variation in the separation rate, whether exogenous or endogenous, greatly in- creases the unemployment variability generated by the model. Speci…cations with exogenous separation rates, whether constant or time-varying, fail to pro- duce realistic volatility and prod...

  16. Molecularly imprinted polyaniline-ferrocene-sulfonic acid-Carbon dots modified pencil graphite electrodes for chiral selective sensing of D-Ascorbic acid and L-Ascorbic acid: A clinical biomarker for preeclampsia

    International Nuclear Information System (INIS)

    Pandey, Indu; Jha, Shashank Shekhar

    2015-01-01

    Highlights: • Pencil graphite electrode was non-covalently functionalized by C-dots. • Electrochemically synthesized ferrocene-sulfonic acid doped PANI film was used as chiral recognition element. • Electrochemical chiral sensing of L-ascorbic acid and D-ascorbic acid was carried out. • L-ascorbic acid determination was done in aqueous, biological and pharmaceutical samples at nM level. - Abstract: A simple and novel method is proposed for chiral separation of L-ascorbic acid and D-ascorbic acid in human cerebrospinal fluids and blood plasma samples. Electro-polymerized molecularly imprinted poly-aniline ferrocenesulfonic acid-C-dots modified pencil graphite electrodes was successfully applied for separation and quantification of D-/L-ascorbic acid in aqueous and some biological samples. Parameters, important to control the performance of the electrochemical sensor were investigated and optimized, including the effects of pH, monomer- template ratios, electropolymerization cycles and scan rates. The molecularly imprinted film exhibited a high chiral selectivity and sensitivity towards D-ascorbic acid and L-ascorbic acid respectively. The surface morphologies and electrochemical properties of the proposed sensor were characterized by scanning electron microscopy, cyclic voltammetry, difference pulse voltammetry, chrono-amperometry and electrochemical impedance spectroscopy. L-ascorbic acid selective sensor shows excellent selectivity towards the L-ascorbic acid in comparison to D- ascorbic acid vice versa for D- ascorbic acid selective sensor. Under optimal conditions the linear range of the calibration curve for L- ascorbic acid and D- ascorbic acid was 6.0–165.0 nM and 6.0–155.0 nM, with the detection limit of 0.001 nM and 0.002 nM. Chiral detection of L-ascorbic acid was successfully carried out in pharmaceuticals and human plasma samples (pregnant women and non pregnant women) via proposed sensor with good selectivity and sensitivity.

  17. 21 CFR 582.3013 - Ascorbic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ascorbic acid. 582.3013 Section 582.3013 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... Ascorbic acid. (a) Product. Ascorbic acid. (b) Conditions of use. This substance is generally recognized as...

  18. 21 CFR 582.5013 - Ascorbic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ascorbic acid. 582.5013 Section 582.5013 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5013 Ascorbic acid. (a) Product. Ascorbic acid. 1 Amino acids listed in this subpart may be...

  19. 21 CFR 182.8013 - Ascorbic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ascorbic acid. 182.8013 Section 182.8013 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8013 Ascorbic acid. (a) Product. Ascorbic acid. (b) Conditions of use. This substance is generally recognized as safe when used in...

  20. Metabolic response to exogenous ethanol in yeast

    Indian Academy of Sciences (India)

    In this study, we applied this approach to evaluate the effects of increasing concentration of exogenous ethanol on the Saccharomyces cerevisiae fermentative metabolism. We show that the STOCSY analysis correctly identifies the different types of correlations among the enriched metabolites involved in the fermentation, ...

  1. Explaining Cigarette Smoking: An Endogenous-Exogenous Analysis.

    Science.gov (United States)

    McKillip, Jack

    Kruglanski's endogenous-exogenous partition, when applied to reasons given by smokers for smoking cigarettes, distinguishes two types of actions: (1) endogenous reasons implying that the behavior of consuming the cigarette is the goal of the action and the actor is positive toward the behavior, and (2) exogenous reasons implying that the behavior…

  2. Sensitive spectrophotometric determination of ascorbic acid in drugs and foods using surface plasmon resonance band of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Kobra Zarei

    2015-12-01

    Full Text Available A simple and sensitive procedure was proposed for spectrophotometric determination of ascorbic acid. It was found that the reduction of Ag+ to silver nanoparticles (Ag-NPs by ascorbic acid in the presence of polyvinylpyrrolidone (PVP as a stabilizing agent produce very intense surface plasmon resonance peak of Ag-NPs. The plasmon absorbance of the Ag-NPs at λ = 440 nm allows the quantitative spectrophotometric detection of the ascorbic acid. The calibration curve was linear with concentration of ascorbic acid in the range of 0.5–60 μM. The detection limit was obtained as 0.08 μM. The influence of potential interfering substances on the determination of ascorbic acid was studied. The proposed method was successfully applied for the determination of ascorbic acid in some powdered drink mixtures, commercial orange juice, natural orange juice, vitamin C injection, effervescent tablet, and multivitamin tablet.

  3. Exogenous lipid pneumonia

    International Nuclear Information System (INIS)

    Bernasconi, A.; Gavelli, G.; Zompatori, M.; Galleri, C.; Zanasi, A.; Fabbri, M.; Bazzocchi, F.

    1988-01-01

    Exogenous lipid pneumonia (ELP) is caused by the aspiration of animal, vegetal or, more often, mineral oils. Even though it may also be acute, ELP is most frequently a chronic disease, affecting people with predisposing factors, such as neuromuscular disorders, structural abnormalities and so on; very often exogenous lipid pneumonia is found in tracheotomized patients. The pathology of lipid pneumonia is a chronic inflammatory process evolving in foreign-body-like reaction, and eventually in ''end-stage lung'' condition. Clinically, most patients are asymptomatic; few cases only present with cough, dyspnea and chest pain. Eight cases of ELP, studied over the past 3 years, are described in this paper. All the patients were examined by chest radiographs and standard tomograms; 3 patients underwent CT. X-ray features were mono/bilateral consolidation of the lower zones, with air bronchogram and variable reduction in volume. CT density was not specific for fat tissue. In all cases the diagnosis was confirmed at biopsy. In 5 patients, followed for at least one year, clinical-radiological features showed no change. Thus, complications of ELP (especially malignant evolution) could be excluded. The authors conclude that lipid pneumonia must be considered in differential diagnosis of patients with history of usage of oils and compatible X-ray findings. The usefulness of an accurate follow-up is stressed

  4. 21 CFR 182.3013 - Ascorbic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ascorbic acid. 182.3013 Section 182.3013 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... acid. (a) Product. Ascorbic acid. (b) Conditions of use. This substance is generally recognized as safe...

  5. Study of Ascorbic Acid as Iron(III Reducing Agent for Spectrophotometric Iron Speciation

    Directory of Open Access Journals (Sweden)

    Antesar Elmagirbi

    2012-10-01

    Full Text Available The study of ascorbic acid as a reducing agent for iron(III has been investigated in order to obtain an alternative carcinogenic reducing agent, hydroxylamine, used in spectrophotometric standard method based on the formation of a red-orange complex of Fe(II-o-phenanthroline. The study was optimised with regards to ascorbic acid concentration as well as pH solution. The results showed that ascorbic acid showed maximum capacity as reducing agent of iron(III under concentration of 4.46.10-4 M and pH solution of 1-4.Under these conditions, ascorbic acid reduced iron(III proportionally and performed similarly to that of hydroxylamine.  The method gave result to linear calibration over the range of 0.2-2 mg/L withhigh accuracy of 97 % and relative standard deviation of less than 2 %. This method was successfully applied to assay iron speciation in water samples.

  6. Performance of structured lipids incorporating selected phenolic and ascorbic acids.

    Science.gov (United States)

    Gruczynska, Eliza; Przybylski, Roman; Aladedunye, Felix

    2015-04-15

    Conditions applied during frying require antioxidant which is stable at these conditions and provides protection for frying oil and fried food. Novel structured lipids containing nutraceuticals and antioxidants were formed by enzymatic transesterification, exploring canola oil and naturally occurring antioxidants such as ascorbic and selected phenolic acids as substrates. Lipozyme RM IM lipase from Rhizomucor miehei was used as biocatalyst. Frying performance and oxidative stability of the final transesterification products were evaluated. The novel lipids showed significantly improved frying performance compared to canola oil. Oxidative stability assessment of the structured lipids showed significant improvement in resistance to oxidative deterioration compared to original canola oil. Interestingly, the presence of ascorbic acid in an acylglycerol structure protected α-tocopherol against thermal degradation, which was not observed for the phenolic acids. Developed structured lipids containing nutraceuticals and antioxidants may directly affect nutritional properties of lipids also offering nutraceutical ingredients for food formulation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Tumorigenicity of sodium ascorbate in male rats.

    Science.gov (United States)

    Cohen, S M; Anderson, T A; de Oliveira, L M; Arnold, L L

    1998-06-15

    Sodium ascorbate, like other sodium salts such as saccharin, glutamate, and bicarbonate, produces urinary alterations when fed at high doses to rats, which results in mild superficial urothelial cytotoxicity and regeneration but not tumors in a standard 2-year bioassay. Sodium saccharin was shown to produce a low incidence of bladder tumors in rats if administered in a two-generation bioassay. In the present study, we evaluated sodium ascorbate in a two-generation bioassay that involved feeding to the male and female parental F344 rats for 4 weeks before mating, feeding the dams during gestation and lactation, and then feeding the weaned (at 28 days of age) male F1 generation rats for the remainder of their lifetime (up to 128 weeks of the experiment). Dietary levels of 1.0, 5.0, and 7.0% sodium ascorbate were tested. At 5.0 and 7.0% sodium ascorbate, there was an increase in urinary bladder urothelial papillary and nodular hyperplasia and the induction of a few papillomas and carcinomas. There was a dose-responsive increase in renal pelvic calcification and hyperplasia and inhibition of the aging nephropathy of rats even at the level of 1% sodium ascorbate. Because the short-term urothelial effects of sodium ascorbate in rats are inhibited by treatments producing urinary acidification to pH sodium ascorbate to evaluate the long-term effects. The combination of 7.0% sodium ascorbate plus 2.78% NH4Cl in the diet was toxic, and the group was terminated early during the course of the experiment. The group fed 5.0% sodium ascorbate plus 2.04% NH4Cl showed complete inhibition of the urothelial effects of sodium ascorbate and significant inhibition of its renal effects. We also demonstrated the presence of a calcium phosphate-containing urinary precipitate in rats fed sodium ascorbate at all doses, in a dose-responsive manner. The formation of the precipitate was inhibited by coadministration with NH4Cl. The proliferative effects of sodium ascorbate on the male rat

  8. Fate of the synergistic antioxidant system ascorbic acid, lecithin, and tocopherol in mayonnaise: Partion of ascorbic acid

    DEFF Research Database (Denmark)

    Meyer, Anne Merete Boye; Jacobsen, Charlotte Munch

    1996-01-01

    Meyer, A. S. & C. Jacobsen, 1996. Fate of the synergistic antioxidant system ascorbic acid, lecithin, and tocopherol in mayonnaise: Partion of ascorbic acid, J. Food Lipids, 3, 139-147.......Meyer, A. S. & C. Jacobsen, 1996. Fate of the synergistic antioxidant system ascorbic acid, lecithin, and tocopherol in mayonnaise: Partion of ascorbic acid, J. Food Lipids, 3, 139-147....

  9. Interference of ascorbic acid with chemical analytes.

    Science.gov (United States)

    Meng, Qing H; Irwin, William C; Fesser, Jennifer; Massey, K Lorne

    2005-11-01

    Ascorbic acid can interfere with methodologies involving redox reactions, while comprehensive studies on main chemistry analysers have not been reported. We therefore attempted to determine the interference of ascorbic acid with analytes on the Beckman Synchron LX20. Various concentrations of ascorbic acid were added to serum, and the serum analytes were measured on the LX20. With a serum ascorbic acid concentration of 12.0 mmol/L, the values for sodium, potassium, calcium and creatinine increased by 43%, 58%, 103% and 26%, respectively (Pascorbic acid concentration of 12.0 mmol/L, the values for chloride, total bilirubin and uric acid decreased by 33%, 62% and 83%, respectively (Pcholesterol, triglyceride, ammonia and lactate. There was no definite influence of ascorbic acid on analytical values for total CO(2), urea, glucose, phosphate, total protein, albumin, amylase, creatine kinase, creatine kinase-MB, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total iron, unbound iron-binding capacity or magnesium. Ascorbic acid causes a false increase in sodium, potassium, calcium and creatinine results and a false decrease in chloride, total bilirubin, uric acid, total cholesterol, triglyceride, ammonia and lactate results.

  10. A highly sensitive kinetic spectrophotometric method for the determination of ascorbic Acid in pharmaceutical samples.

    Science.gov (United States)

    Shishehbore, Masoud Reza; Aghamiri, Zahra

    2014-01-01

    In this study, a new reaction system for quantitative determination of ascorbic acid was introduced. The developed method is based on inhibitory effect of ascorbic acid on the Orange G-bromate system. The change in absorbance was followed spectrophotometrically at 478 nm. The dependence of sensitivity on the reaction variables including reagents concentration, temperature and time was investigated. Under optimum experimental conditions, calibration curve was linear over the range 0.7 - 33.5 μg mL(-1) of ascorbic acid including two linear segments and the relative standard deviations (n = 6) for 5.0 and 20.0 μg mL(-1) of ascorbic acid were 1.08 and 1.02%, respectively. The limit of detection was 0.21 μg mL(-) (1) of ascorbic acid. The effect of diverse species was also investigated. The developed method was successfully applied for the determination of ascorbic acid in pharmaceutical samples. The results were in a good agreement with those of reference method.

  11. Static magnetic field reduced exogenous oligonucleotide uptake by spermatozoa using magnetic nanoparticle gene delivery system

    International Nuclear Information System (INIS)

    Katebi, Samira; Esmaeili, Abolghasem; Ghaedi, Kamran

    2016-01-01

    Spermatozoa could introduce exogenous oligonucleotides of interest to the oocyte. The most important reason of low efficiency of sperm mediated gene transfer (SMGT) is low uptake of exogenous DNA by spermatozoa. The aim of this study was to evaluate the effects of static magnetic field on exogenous oligonucleotide uptake of spermatozoa using magnetofection method. Magnetic nanoparticles (MNPs) associated with the labeled oligonucleotides were used to increase the efficiency of exogenous oligonucleotide uptake by rooster spermatozoa. We used high-field/high-gradient magnet (NdFeB) to enhance and accelerate exogenous DNA sedimentation at the spermatozoa surface. Flow cytometry analysis was performed to measure viability and percentage of exogenous oligonucleotide uptake by sperm. Flow cytometry analysis showed a significant increase in exogenous oligonucleotide uptake by rooster spermatozoa (P<0.001) when spermatozoa were incubated in exogenous oligonucleotide solution and MNPs. However, by applying static magnetic field during magnetofection method, a significant decrease in exogenous oligonucleotide uptake was observed (P<0.05). Findings of this study showed that MNPs were effective to increase exogenous oligonucleotide uptake by rooster spermatozoa; however unlike others studies, static magnetic field, was not only ineffective to enhance exogenous oligonucleotide uptake by rooster spermatozoa but also led to reduction in efficiency of magnetic nanoparticles in gene transfer. - Highlights: • Core/shell type Iron oxide nanoparticles were used as a novel and efficient method. • This method increases exogenous DNA uptake by rooster spermatozoa. • Static magnetic field decreased DNA uptake by rooster spermatozoa.

  12. Static magnetic field reduced exogenous oligonucleotide uptake by spermatozoa using magnetic nanoparticle gene delivery system

    Energy Technology Data Exchange (ETDEWEB)

    Katebi, Samira; Esmaeili, Abolghasem, E-mail: aesmaeili@sci.ui.ac.ir; Ghaedi, Kamran

    2016-03-15

    Spermatozoa could introduce exogenous oligonucleotides of interest to the oocyte. The most important reason of low efficiency of sperm mediated gene transfer (SMGT) is low uptake of exogenous DNA by spermatozoa. The aim of this study was to evaluate the effects of static magnetic field on exogenous oligonucleotide uptake of spermatozoa using magnetofection method. Magnetic nanoparticles (MNPs) associated with the labeled oligonucleotides were used to increase the efficiency of exogenous oligonucleotide uptake by rooster spermatozoa. We used high-field/high-gradient magnet (NdFeB) to enhance and accelerate exogenous DNA sedimentation at the spermatozoa surface. Flow cytometry analysis was performed to measure viability and percentage of exogenous oligonucleotide uptake by sperm. Flow cytometry analysis showed a significant increase in exogenous oligonucleotide uptake by rooster spermatozoa (P<0.001) when spermatozoa were incubated in exogenous oligonucleotide solution and MNPs. However, by applying static magnetic field during magnetofection method, a significant decrease in exogenous oligonucleotide uptake was observed (P<0.05). Findings of this study showed that MNPs were effective to increase exogenous oligonucleotide uptake by rooster spermatozoa; however unlike others studies, static magnetic field, was not only ineffective to enhance exogenous oligonucleotide uptake by rooster spermatozoa but also led to reduction in efficiency of magnetic nanoparticles in gene transfer. - Highlights: • Core/shell type Iron oxide nanoparticles were used as a novel and efficient method. • This method increases exogenous DNA uptake by rooster spermatozoa. • Static magnetic field decreased DNA uptake by rooster spermatozoa.

  13. A comparative analysis of property of lychee polyphenoloxidase using endogenous and exogenous substrates.

    Science.gov (United States)

    Sun, Jian; Shi, John; Zhao, Mouming; Xue, Sophia Jun; Ren, Jiaoyan; Jiang, Yueming

    2008-06-01

    Lychee polyphenoloxidase (PPO) was extracted and partially purified using ammonium sulphate precipitation and dialysis. The comparative analysis of PPO property was performed using its endogenous substrate (-)-epicatechin and exogenous substrate catechol. The pH optima for activity and activation temperature profiles of lychee PPO were very different when the enzyme reacted with endogenous and exogenous substrates. The addition of ethylenediaminetetraacetic acid disodium salt into the endogenous or exogenous substrate-enzyme system exhibited the same lowest inhibition of the PPO activity. However, l-cysteine was most effective in inhibiting enzymatic activity in the endogenous substrate-enzyme system while ascorbic acid was the best inhibitor in the exogenous substrate-enzyme system. Fe(2+) greatly accelerated the enzymatic reaction between endogenous substrate and PPO, but Cu(2+) exerted the same effect on the reaction between exogenous substrate and PPO. Based on the kinetic analysis, lychee PPO could strongly bind endogenous substrate but it possessed a higher catalytic efficiency to exogenous substrate. Copyright © 2007 Elsevier Ltd. All rights reserved.

  14. Ascorbic acid as a bifunctional hydrogen bond donor for the synthesis of cyclic carbonates from CO2 under ambient conditions

    KAUST Repository

    Arayachukiat, Sunatda

    2017-07-14

    Readily available ascorbic acid was discovered as an environmentally benign hydrogen bond donor (HBD) for the synthe-sis of cyclic organic carbonates from CO2 and epoxides in the presence of nucleophilic co-catalysts. The ascorbic acid/TBAI (TBAI: tetrabutylammonium iodide) binary system could be applied for the cycloaddition of CO2 to various epoxides under ambient or mild conditions. DFT calculations and catalysis experiments revealed an intriguing bifunctional mechanism in the step of CO2 insertion involving different hydroxyl moieties (enediol, ethyldiol) of the ascorbic acid scaffold.

  15. Ascorbic acid as a bifunctional hydrogen bond donor for the synthesis of cyclic carbonates from CO2 under ambient conditions

    KAUST Repository

    Arayachukiat, Sunatda; Kongtes, Chutima; Barthel, Alexander; Vummaleti, Sai V. C.; Poater, Albert; Wannakao, Sippakorn; Cavallo, Luigi; D'Elia, Valerio

    2017-01-01

    Readily available ascorbic acid was discovered as an environmentally benign hydrogen bond donor (HBD) for the synthe-sis of cyclic organic carbonates from CO2 and epoxides in the presence of nucleophilic co-catalysts. The ascorbic acid/TBAI (TBAI: tetrabutylammonium iodide) binary system could be applied for the cycloaddition of CO2 to various epoxides under ambient or mild conditions. DFT calculations and catalysis experiments revealed an intriguing bifunctional mechanism in the step of CO2 insertion involving different hydroxyl moieties (enediol, ethyldiol) of the ascorbic acid scaffold.

  16. Drug Nanoparticle Formulation Using Ascorbic Acid Derivatives

    Directory of Open Access Journals (Sweden)

    Kunikazu Moribe

    2011-01-01

    Full Text Available Drug nanoparticle formulation using ascorbic acid derivatives and its therapeutic uses have recently been introduced. Hydrophilic ascorbic acid derivatives such as ascorbyl glycoside have been used not only as antioxidants but also as food and pharmaceutical excipients. In addition to drug solubilization, drug nanoparticle formation was observed using ascorbyl glycoside. Hydrophobic ascorbic acid derivatives such as ascorbyl mono- and di-n-alkyl fatty acid derivatives are used either as drugs or carrier components. Ascorbyl n-alkyl fatty acid derivatives have been formulated as antioxidants or anticancer drugs for nanoparticle formulations such as micelles, microemulsions, and liposomes. ASC-P vesicles called aspasomes are submicron-sized particles that can encapsulate hydrophilic drugs. Several transdermal and injectable formulations of ascorbyl n-alkyl fatty acid derivatives were used, including ascorbyl palmitate.

  17. Endogenous versus exogenous shocks in systems with memory

    Science.gov (United States)

    Sornette, D.; Helmstetter, A.

    2003-02-01

    Systems with long-range persistence and memory are shown to exhibit different precursory as well as recovery patterns in response to shocks of exogenous versus endogenous origins. By endogenous, we envision either fluctuations resulting from an underlying chaotic dynamics or from a stochastic forcing origin which may be external or be an effective coarse-grained description of the microscopic fluctuations. In this scenario, endogenous shocks result from a kind of constructive interference of accumulated fluctuations whose impacts survive longer than the large shocks themselves. As a consequence, the recovery after an endogenous shock is in general slower at early times and can be at long times either slower or faster than after an exogenous perturbation. This offers the tantalizing possibility of distinguishing between an endogenous versus exogenous cause of a given shock, even when there is no “smoking gun”. This could help in investigating the exogenous versus self-organized origins in problems such as the causes of major biological extinctions, of change of weather regimes and of the climate, in tracing the source of social upheaval and wars, and so on. Sornette et al., Volatility fingerprints of large stocks: endogenous versus exogenous, cond-mat/0204626 has already shown how this concept can be applied concretely to differentiate the effects on financial markets of the 11 September 2001 attack or of the coup against Gorbachev on 19 August 1991 (exogenous) from financial crashes such as October 1987 (endogenous).

  18. Exogenously applied D-pinitol and D-chiro-inositol modifies the accumulation of α-D-galactosides in developing tiny vetch (Vicia hirsuta [L.] S.F. Gray seeds

    Directory of Open Access Journals (Sweden)

    Lesław B. Lahuta

    2011-01-01

    Full Text Available In the present study we have investigated the effect of exogenous cyclitols on the accumulation of their galactosides and raffinose family oligosaccharides (RFOs, as well as on some enzymes important for their biosynthesis in seeds of tiny vetch (Vicia hirsuta [L.] S.F. Gray. Immature seeds during 6-day incubation with D-chiro-inositol (naturally does not appear in seeds of tiny vetch were accumulated cyclitol and its galactosides (fagopyritols: B1 and B2. Short 4-hour incubation with D-chiro-inositol, and subsequent slow desiccation process caused accumulation of free cyclitol only, without biosynthesis of its galactosides. Feeding D-chiro-inositol to pods of tiny vetch induced accumulation of high levels of its galactosides (fagopyritol B1, B2 and B3 in maturing seeds. Similarly, feeding D-pinitol increased accumulation of its mono-, di- and tri-galactosides: GPA, GPB, DGPA and TGPA in tiny vetch seed. Accumulation of both cyclitols and their galactosides drastically reduced accumulation of verbascose. Inhibition of RFOs biosynthesis by elevated levels of free cyclitols suggests some competition between formation of both types of galactosides and similarity of both biosynthetic routes in tiny vetch seeds. Galactinol synthase (GolS from tiny vetch seeds demonstrated ability to utilize D-chiro-inositol as galactosyl acceptor, instead of myo-inositol. Presence of both cyclitols, as substrates for GolS, caused synthesis of their galactosides: fagopyritol B1 and galactinol. However, formation of galactinol was more efficient than fagopyritol B1. D-chiro-Inositol and D-pinitol at concentrations several-fold higher than myo-inositol had inhibitory effect on GolS. Thus, we suggest that a level of free cyclitols can have an influence on the rate of galactinol biosynthesis and further accumulation of RFOs and galactosyl cyclitols in tiny vetch seeds.

  19. Role of ascorbic acid in the inhibition of polyphenol oxidase and the prevention of browning in different browning-sensitive Lactuca sativa var. capitata (L.) and Eruca sativa (Mill.) stored as fresh-cut produce.

    Science.gov (United States)

    Landi, Marco; Degl'Innocenti, Elena; Guglielminetti, Lorenzo; Guidi, Lucia

    2013-06-01

    Polyphenol oxidase (PPO) and, to a minor extent, peroxidase (POD) represent the key enzymes involved in enzymatic browning, a negative process induced by cutting fresh-cut produce such as lettuce (Lactuca sativa) and rocket salad (Eruca sativa). Although ascorbic acid is frequently utilised as an anti-browning agent, its mechanism in the prevention of the browning phenomenon is not clearly understood. The activity of PPO and POD and their isoforms in lettuce (a high-browning and low-ascorbic acid species) and rocket salad (a low-browning and high-ascorbic species) was characterised. The kinetic parameters of PPO and in vitro ascorbic acid-PPO inhibition were also investigated. In rocket salad, PPO activity was much lower than that in lettuce and cutting induced an increase in PPO activity only in lettuce. Exogenous ascorbic acid (5 mmol L(-1)) reduced PPO activity by about 90% in lettuce. POD did not appear to be closely related to browning in lettuce. PPO is the main enzyme involved in the browning phenomenon; POD appears to play a minor role. The concentration of endogenous ascorbic acid in rocket salad was related to its low-browning sensitivity after cutting. In lettuce, the addition of ascorbic acid directly inhibited PPO activity. The results suggest that the high ascorbic acid content found in rocket salad plays an effective role in reducing PPO activity. © 2012 Society of Chemical Industry.

  20. Sequential injection redox or acid-base titration for determination of ascorbic acid or acetic acid.

    Science.gov (United States)

    Lenghor, Narong; Jakmunee, Jaroon; Vilen, Michael; Sara, Rolf; Christian, Gary D; Grudpan, Kate

    2002-12-06

    Two sequential injection titration systems with spectrophotometric detection have been developed. The first system for determination of ascorbic acid was based on redox reaction between ascorbic acid and permanganate in an acidic medium and lead to a decrease in color intensity of permanganate, monitored at 525 nm. A linear dependence of peak area obtained with ascorbic acid concentration up to 1200 mg l(-1) was achieved. The relative standard deviation for 11 replicate determinations of 400 mg l(-1) ascorbic acid was 2.9%. The second system, for acetic acid determination, was based on acid-base titration of acetic acid with sodium hydroxide using phenolphthalein as an indicator. The decrease in color intensity of the indicator was proportional to the acid content. A linear calibration graph in the range of 2-8% w v(-1) of acetic acid with a relative standard deviation of 4.8% (5.0% w v(-1) acetic acid, n=11) was obtained. Sample throughputs of 60 h(-1) were achieved for both systems. The systems were successfully applied for the assays of ascorbic acid in vitamin C tablets and acetic acid content in vinegars, respectively.

  1. Iodometric determination of the ascorbic acid (Vitamin c) content of ...

    African Journals Online (AJOL)

    The ascorbic acid content of seven different fruits –grapefruit, lime, orange, tangerine, banana, pawpaw and pineapple was determined by iodine titration, in order to know which fruit would best supply the ascorbic acid need for the body. Results showed that tangerine had the highest value of ascorbic acid, ...

  2. Higher transcription levels in ascorbic acid biosynthetic and recycling genes were associated with higher ascorbic acid accumulation in blueberry.

    Science.gov (United States)

    Liu, Fenghong; Wang, Lei; Gu, Liang; Zhao, Wei; Su, Hongyan; Cheng, Xianhao

    2015-12-01

    In our preliminary study, the ripe fruits of two highbush blueberry (Vaccinium corymbosum L.) cultivars, cv 'Berkeley' and cv 'Bluecrop', were found to contain different levels of ascorbic acid. However, factors responsible for these differences are still unknown. In the present study, ascorbic acid content in fruits was compared with expression profiles of ascorbic acid biosynthetic and recycling genes between 'Bluecrop' and 'Berkeley' cultivars. The results indicated that the l-galactose pathway was the predominant route of ascorbic acid biosynthesis in blueberry fruits. Moreover, higher expression levels of the ascorbic acid biosynthetic genes GME, GGP, and GLDH, as well as the recycling genes MDHAR and DHAR, were associated with higher ascorbic acid content in 'Bluecrop' compared with 'Berkeley', which indicated that a higher efficiency ascorbic acid biosynthesis and regeneration was likely to be responsible for the higher ascorbic acid accumulation in 'Bluecrop'. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Spectrophotometric determination of copper with ascorbic acid

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, A; Mustafa, M M; Asma, R N; Sareecha, N [Islamia Univ., Bahawalpur (Pakistan). Chemistry Dept.

    1996-06-01

    Copper has been determined spectrophotometrically by using ascorbic acid as a chromagenic reagent. The complex formed in basic medium is measured for its absorbance at 340 n.m. Interference for 23 cations and 9 anions has also been checked. Effect of pH, time, temperature, ammonia, reagent concentration and interferents has been report. (author).

  4. Spectrophotometric determination of copper with ascorbic acid

    International Nuclear Information System (INIS)

    Majeed, A.; Mustafa, M.M.; Asma, R.N.; Sareecha, N.

    1996-01-01

    Copper has been determined spectrophotometrically by using ascorbic acid as a chromagenic reagent. The complex formed in basic medium is measured for its absorbance at 340 n.m. Interference for 23 cations and 9 anions has also been checked. Effect of pH, time, temperature, ammonia, reagent concentration and interferents has been report. (author)

  5. Consequences and detection of invalid exogeneity conditions

    NARCIS (Netherlands)

    Niemczyk, J.

    2009-01-01

    Estimators for econometric relationships require observations on at least as many exogenous variables as the model has unknown coefficients. This thesis examines techniques to classify variables as being either exogenous or endogenous, and investigates the consequences of invalid classifications.

  6. sup(99)Tcsup(m)-ascorbate

    International Nuclear Information System (INIS)

    Persson, R.B.R.; Strand, S.E.; White, T.

    1975-01-01

    The sup(99)Tcsup(m)-ascorbate preparation used in this investigation contained FeCl 3 4mN, asorbic acid 110 mM and had an initial pH-value of 7.4 and a final pH-value of 6.8. Studies of the complex-formation were performed with gel-chromatography column-scanning (GCS), which is the analytical method to be preferred for this type of compound, indicated that the complex was formed in two steps. First reduced hydrolyzed sup(99)Tcsup(m) was formed rapidly and the sup(99)Tcsup(m)-ascorbate was formed by a slower reaction (k = 3, 10 -2 min -1 ). The renal uptake of sup(99)Tcsup(m)- was studied in 29 patients with a gamma-camera. The time-course of radio-activity in kidneys, 'tissue background'-areas and in blood suggested that optimal conditions for kidney-imaging were reached 3 to 6 hr after injection. About 20% of the sup(99)Tcsup(m)-ascorbate was bound to plasma-proteins, and only a small fraction to red blood-cells. The disappearance of the sup(99)Tcsup(m)-ascorbate from plasma followed a three-exponential curve: 40% with a half-life of 0.2 hr, 30% with a half-life of 20 hr. The absorbed radiation dose to the kidneys was about 200 (SE +- 60) mrad mCi -1 and to the whole-body 10 (SE +- 3) mrad mCi -1 of administered activity. There was a close correlation (r + 0.98) of the separate renal uptake (dx:(dx +sin)) of sup(99)Tcsup(m)-ascorbate to the separate renal function as determined with 131 I-Hippuran. (author)

  7. Exogenic and endogenic Europa minerals

    Science.gov (United States)

    Maynard-Casely, H. E.; Brand, H. E. A.; Wilson, S. A.

    2016-12-01

    The Galileo Near Infrared Mapping Spectrometer (NIMS) identified a significant `non-ice' component upon the surface of Jupiter's moon Europa. Current explanations invoke both endogenic and exogenic origins for this material. It has long been suggested that magnesium and sodium sulfate minerals could have leached from the rock below a putative ocean (endogenic) 1 and that sulfuric acid hydrate minerals could have been radiologically produced from ionised sulfur originally from Io's volcanoes (exogenic) 2. However, a more recent theory proposes that the `non-ice' component could be radiation damaged NaCl leached from Europa's speculative ocean 3. What if the minerals are actually from combination of both endogenic and exogenic sources? To investigate this possibility we have focused on discovering new minerals that might form in the combination of the latter two cases, that is a mixture of leached sulfates hydrates with radiologically produced sulfuric acid. To this end we have explored a number of solutions in the MgSO4-H2SO4-H2O and Na2SO4-H2SO4-H2O systems, between 80 and 280 K with synchrotron x-ray powder diffraction. We report a number of new materials formed in this these ternary systems. This suggests that it should be considered that the `non-ice' component of the Europa's surface could be a material derived from endogenic and exogenic components. 1 Kargel, J. S. Brine volcanism and the interior structures of asteroids and icy satellites. Icarus 94, 368-390 (1991). 2 Carlson, R. W., Anderson, M. S., Mehlman, R. & Johnson, R. E. Distribution of hydrate on Europa: Further evidence for sulfuric acid hydrate. Icarus 177, 461-471, doi:10.1016/j.icarus.2005.03.026 (2005). 3 Hand, K. P. & Carlson, R. W. Europa's surface color suggests an ocean rich with sodium chloride. Geophysical Research Letters, 2015GL063559, doi:10.1002/2015gl063559 (2015).

  8. The Use of Ascorbic Acid as a Food Additive: Technical-Legal Issues

    Science.gov (United States)

    Varvara, Michele; Bozzo, Giancarlo; Celano, Giuseppe; Disanto, Chiara; Pagliarone, Cosimo Nicola

    2016-01-01

    Ascorbic acid (C6H8O6) is an organic compound belonging to the family of monosaccharide. It is highly soluble in water, and is often called one of the secrets of the Mediterranean diet. Its use is widespread in the food industry is also important, having always been exploited for its antioxidant and stabilising ability. Many indeed are the additive formulations that take advantage of these properties. The purpose of this paper is to explain the characteristics that make ascorbic acid an important food additive and to emphasise the technical and legal issues related to its use in food productions. In particular, in the course of this employment, laws and scientific studies have been applied to the resolution of a lawsuit, having as its object the use of ascorbic acid in preparations of ground beef sold at a butcher shop. The views expressed in court by the technical consultant have led to the acquittal of the accused, in the light of the demonstrated and proven non-toxicity of the molecule and the use of a mixture of additives for the production of sausage. The European and national legislations, supported by numerous scientific studies, define the possible use of ascorbic acid according to the principle of quantum satis, and it can be used in foods for children. Our work aims to represent further evidence of the safety of use of ascorbic acid as a food additive, and – as confirmed by the legal decision reported – it wants to bring out the prospects for use of ascorbic acid for technological purposes even by registered establishments. PMID:27800425

  9. [Effects of exogenous silicon on physiological characteristics of cucumber seedlings under ammonium stress].

    Science.gov (United States)

    Gao, Qing-Hai; Wang, Ya-Kun; Lu, Xiao-Min; Jia, Shuang-Shuang

    2014-05-01

    The present study evaluated the effects of exogenous silicon on growth and physiological characteristics of hydroponically cultured cucumber seedlings under ammonium stress. The results showed that the growth, especially the aerial part growth of cucumber seedlings cultured with ammonium were significantly inhibited than those with nitrate, especially after treatment for 10 d, the aerial part fresh mass of cucumber seedlings were reduced 6.17 g per plant. The accumulation of reactive oxygen species (ROS) was also promoted in cucumber seedlings under ammonium, and the contents of O2*- and H2O2 were significantly increased in cucumber leaves. With the exogenous silicon treatment, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) were significantly improved, the ability to remove reactive oxygen species was enhanced, the contents of O2*- and H2O2 were significantly reduced in cucumber leaves, decreasing the reactive oxygen damage to the cell membrane, and the ratio of electrolyte leakage and the content of MDA in cucumber leaves. Also, with exogenous silicon treatment, the plasma membrane and activity of vacuolar membrane H(+)-ATP was significantly increased, transport capacity of intracellular proton was improved, and the level of ammonium in cucumber body was significantly reduced, thereby reducing the toxicity of ammonium. In conclusion, exogenous silicon could relieve ammonium stress, by increasing the antioxidant enzyme activity, H(+)-ATP activity, and decreasing the ammonium content in cucumber seedlings.

  10. ASCORBIC ACID STATUS IN PREGNANCY AND POSTPARTUM WOMEN IN ENUGU, SOUTH-EAST, NIGERIA: ARE VITAMIN SUPPLEMENTS SUFFICIENT?

    Directory of Open Access Journals (Sweden)

    2017-01-01

    Full Text Available Pregnancy has been shown to be a period of stress, during which the nutritional needs of the foetus is dependent on that of the mother. It is also a condition exhibiting increased susceptibility to oxidative stress, leading to potential damage. Ascorbic acid is a strong antioxidant as well as a reducing agent and is increasingly utilized to normalize the pro-oxidant - antioxidant balance during pregnancy. Since ascorbic acid cannot be synthesized by the body, leading to total dependence on exogenous supply in diets, there is need to evaluate the level of the vitamin in pregnant women and determine their predisposition or otherwise to avitaminosis C. Ascorbic acid levels of 60 apparently healthy pregnant women, aged between 20-40 years old and attending the antenatal clinic at the UNTH, Enugu, 60 age-matched women in their postpartum and 60 age-matched non-pregnant women (controls were assayed using the 2,4-dinitrophenyl hydrazine method. The serum ascorbic acid levels were significantly lower (P and lt;0.05 in pregnant women, showing a steady decline with gestational age increase. There were statistically significant decreases (P and lt;0.05 in the second and third trimesters whereas a significant increase (P and lt;0.05 was observed in the postpartum period, when compared to the controls. The serum levels of ascorbic acid were decreased significantly as pregnancy progresses; in spite of the supplements given Significant increases in the postpartum period may be attributed to the absence of oxidative stress and recovery from stress. Additional supplementation and increased dietary intake should be encouraged in pregnant women.

  11. Control of cucumber (Cucumis sativus L. tolerance to chilling stress – evaluating the role of ascorbic acid and glutathione

    Directory of Open Access Journals (Sweden)

    Alexander S. Lukatkin

    2014-12-01

    Full Text Available Chilling temperatures (1-10 ºC are known to disturb cellular physiology, cause oxidative stress via creating imbalance between generation and metabolism of reactive oxygen species (ROS leading finally to cell and/or plant death. Owing to known significance of low molecular antioxidants - ascorbic acid (AsA and glutathione (GSH in plant stress-tolerance, this work analyzes the role of exogenously applied AsA and GSH in the alleviation of chilling stress (3°C-impact in cucumber (Cucumis sativus L. cv. Vjaznikowskij 37 plants. Results revealed AsA and GSH concentration dependent metabolism of ROS such as superoxide (O2•‾ and the mitigation of ROS-effects such as lipid peroxidation (LPO as well as membrane permeability (measured as electrolyte leakage in C. sativus leaf discs. AsA concentration (750 µM and GSH (100 µM exhibited maximum reduction in O2•‾ generation, LPO intensity as well as electrolyte leakage, all of these were increased in cold water (3°C and 25°C-treated leaf discs. However, AsA, in particular, had a pronounced antioxidative effect, more expressed in case of leaf discs during chilling (3°C; whereas, at temperature 25°C, some AsA concentrations (such as 50 and 100 mM AsA exhibited a prooxidative effect that requires molecular-genetic studies. Overall, it is inferred that AsA and GSH have high potential for sustainably increasing chilling-resistance in plants.

  12. Alleviation of isoproturon toxicity to wheat by exogenous application of glutathione.

    Science.gov (United States)

    Nemat Alla, Mamdouh M; Hassan, Nemat M

    2014-06-01

    Treatment with the recommended field dose of isoproturon to 7-d-old wheat seedlings significantly decreased shoot height, fresh and dry weights during the subsequent 15days. Meanwhile contents of carotenoids, chlorophylls and anthocyanin as well as activities of δ-aminolevulinate dehydratase (ALA-D), phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) were significantly inhibited. On the other hand, the herbicide significantly increased malondialdehyde (MDA), a naturally occurring product of lipid peroxidation and H2O2, while it significantly decreased the contents of glutathione (GSH) and ascorbic acid (AsA) and reduced the activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). These findings indicate an induction of a stress status in wheat seedlings following isoproturon treatment. However, exogenous GSH appeared to limit the toxic effects of isoproturon and seemed to overcome this stress status. Most likely, contents of pigment and activities of enzymes were raised to approximate control levels. Moreover, antioxidants were elevated and the oxidative stress indices seemed to be alleviated by GSH application. These results indicate that exogenous GSH enhances enzymatic and nonenzymatic antioxidants to alleviate the effects of isoproturon. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Determination of ascorbic acid in pharmaceutical preparation and fruit juice using modified carbon paste electrode

    Directory of Open Access Journals (Sweden)

    Simona Žabčíková

    2016-06-01

    Full Text Available Acrobic acid is key substance in the human metabolism and the rapid and accurate determination in food is of a great interest. Ascorbic acid is an electroactive compound, however poorly responded on the bare carbon paste electrodes. In this paper, brilliant cresyl blue and multi-walled carbon nanotubes were used for the modification of carbon paste electrode. Brilliant cresyl blue acts as a mediator improving the transition of electrons, whereas multiwalled carbon nanotubes increased the surface of the electrode. Both brilliant cresyl blue and multiwalled carbon nanotubes were added directly to the composite material. The electrochemical behavior of modified electode was determined in electrolyte at various pH, and the effect of the scan rate was also performed. It was shown that the electrochemical process on the surface of the modified carbon paste electrode was diffusion-controlled. The resulted modified carbon paste electrode showed a good electrocatalytic activity towards the oxidation of ascorbic acid at a reduced overpotential of +100 mV descreasing the risk of interferences. A linear response of the ascorbic acid oxidation current measured by the amperometry in the range of 0.1 - 350 µmol.L-1 was obtained applying the sensor for the standard solution. The limit of detection and limit of quantification was found to be 0.05 and 0.15 µmol.L-1, respectively. The novel method was applied for the determination of ascorbic acid in pharmaceutical vitamin preparation and fruit juice, and the results were in good agreement with the standard HPLC method. The presented modification of carbon paste electrode is suitable for the fast, sensitive and very accurate determination of ascorbic acid in fruit juices and pharmaceutical preparation.

  14. [Alleviation of salt stress during maize seed germination by presoaking with exogenous sugar].

    Science.gov (United States)

    Zhao, Ying; Yang, Ke-jun; Li, Zuo-tong; Zhao, Chang-jiang; Xu, Jing-yu; Hu, Xue- wei; Shi, Xin-xin; Ma, Li-feng

    2015-09-01

    The maize variety Kenyu 6 was used to study the effects of exogenous glucose (Glc) and sucrose (Suc) on salt tolerance of maize seeds at germination stage under 150 mmol · L(-1) NaCl treatment. Results showed that under salt stress condition, 0.5 mmol · L(-1) exogenous Glc and Suc presoaking could promote seed germination and early seedling growth. Compared with the salt treatment, Glc presoaking increased the shoot length, radicle length and corresponding dry mass up to 1.5, 1.3, 2.1 and 1.8 times, and those of the Suc presoaking treatment increased up to 1.7, 1.3. 2.7 and 1.9 times, respectively. Exogenous Glc and Suc presoaking resulted in decreased levels of thiobarbituric acid reactive substances (TBARS) and hydrogen peroxide (H2O2) content of maize shoot under salt stress, which were lowered by 24.9% and 20.6% respectively. Exogenous Glc and Suc presoaking could increase the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione peroxidase (GPX), glutathione reductase (GR) and induce glucose-6-phosphate dehydrogenase (G6PDH) activity of maize shoot under salt stress. Compared with the salt treatment. Glc presoaking increased the activity of SOD, APX, GPX, GR and G6PDH by 66.2%, 62.9%, 32.0%, 38.5% and 50.5%, and those of the Suc presoaking increased by 67.5%, 59.8%, 30.0%, 38.5% and 50.4%, respectively. Glc and Suc presoaking also significantly increased the contents of ascorbic acid (ASA) and glutathione (GSH), ASA/DHA and GSH/GSSG. The G6PDH activity was found closely related with the strong antioxidation capacity induced by exogenous sugars. In addition, Glc and Suc presoaking enhanced K+/Na+ in maize shoot by 1.3 and 1.4 times of water soaking salt treatment, respectively. These results indicated that exogenous Glc and Suc presoaking could improve antioxidation capacity of maize seeds and maintain the in vivo K+/Na+ ion balance to alleviate the inhibitory effect of salt stress on maize seed germination.

  15. Fate of the synergistic antioxidant system ascorbic acid, lecithin, and tocopherol in mayonnaise : Partition of ascorbic acid

    DEFF Research Database (Denmark)

    Meyer, A.S.; Jacobsen, Charlotte Munch

    1996-01-01

    The distribution of ascorbic acid between the lipid and aqueous phase was investigated in mayonnaises enriched with fish oil containing a synergistic antioxidant mixture of ascorbic acid, lecithin and gamma-tocopherol, i.e., the A/L/T system (Loliger and Saucy 1989). The ascorbic acid was found...... to be located in the aqueous phase indicating that the A/L/T system broke down in mayonnaises. Based on the hypothesis that synergistic antioxidant action between ascorbic acid, lecithin and tocopherol requires that the three components are in close assembly, the results offer an explanation as to why the A...

  16. Modelling the effects of transglutaminase and L-ascorbic acid on substandard quality wheat flour by response surface methodology

    Directory of Open Access Journals (Sweden)

    Šimurina Olivera D.

    2014-01-01

    Full Text Available In recent decade, there have been observed extreme variations in climatic conditions which in combination with inadequate agro techniques lead to decreased quality of mercantile wheat, actally flour. The application of improvers can optimise the quality of substandard wheat flour. This paper focuses to systematic analysis of individual and interaction effects of ascorbic acid and transglutaminase as dough strengthening improvers. The effects were investigated using the Response Surface Methodology. Transglutaminase had much higher linear effect on the rheological and fermentative properties of dough from substandard flour than L-ascorbic acid. Both transglutaminase and L-ascorbic acid additions had a significant linear effect on the increase of bread specific volume. Effects of transglutaminase and ascorbic acid are dependent on the applied concentrations and it is necessary to determine the optimal concentration in order to achieve the maximum quality of the dough and bread. Optimal levels of tested improvers were determined using appropriate statistical techniques which applied the desirability function. It was found that the combination of 30 mg/kg of transglutaminase and 75.8 mg/kg of L-ascorbic acid achieved positive synergistic effect on rheological and fermentative wheat dough properties, as well on textural properties and specific volume of bread made from substandard quality flour.

  17. Endogenous versus exogenous generic reference pricing for pharmaceuticals.

    Science.gov (United States)

    Antoñanzas, F; Juárez-Castelló, C A; Rodríguez-Ibeas, R

    2017-12-01

    In this paper we carry out a vertical differentiation duopoly model applied to pharmaceutical markets to analyze how endogenous and exogenous generic reference pricing influence competition between generic and branded drugs producers. Unlike the literature, we characterize for the exogenous case the equilibrium prices for all feasible relevant reference prices. Competition is enhanced after the introduction of a reference pricing system. We also compare both reference pricing systems on welfare grounds, assuming two different objective functions for health authorities: (i) standard social welfare and (ii) gross consumer surplus net of total pharmaceutical expenditures. We show that regardless of the objective function, health authorities will never choose endogenous reference pricing. When health authorities are paternalistic, the exogenous reference price that maximizes standard social welfare is such that the price of the generic drug is the reference price while the price of the branded drug is higher than the reference price. When health authorities are not paternalistic, the optimal exogenous reference price is such that the price of the branded drug is the reference price while the price of the generic drug is lower than the reference price.

  18. Exogenous melatonin administration is beneficial for male ...

    African Journals Online (AJOL)

    ABSTRACT. Background: A concern in the use of exogenous melatonin as a therapeutic intervention is that it may interfere with reproductive function. Herein, we report that chronic exogenous melatonin administration does not impair male reproductive function during ageing and at old age in male Sprague Dawley rats.

  19. Exogenous melatonin administration is beneficial for male ...

    African Journals Online (AJOL)

    Background: A concern in the use of exogenous melatonin as a therapeutic intervention is that it may interfere with reproductive function. Herein, we report that chronic exogenous melatonin administration does not impair male reproductive function during ageing and at old age in male Sprague Dawley rats. Methods: ...

  20. Computational analysis for biodegradation of exogenously depolymerizable polymer

    Science.gov (United States)

    Watanabe, M.; Kawai, F.

    2018-03-01

    This study shows that microbial growth and decay in a biodegradation process of exogenously depolymerizable polymer are controlled by consumption of monomer units. Experimental outcomes for residual polymer were incorporated in inverse analysis for a degradation rate. The Gauss-Newton method was applied to an inverse problem for two parameter values associated with the microbial population. A biodegradation process of polyethylene glycol was analyzed numerically, and numerical outcomes were obtained.

  1. Lipid peroxidation and ascorbic acid levels in Nigeria children with ...

    African Journals Online (AJOL)

    This study was undertaken to establish data on the roles of lipid peroxidation and ascorbic acid in the pathology of malaria in Nigeria children. We measured the levels of malondialdehyde (MDA), a marker of lipid peroxidation and ascorbic acid in the plasma of 406 parasitaemic and 212 non-parasitaemic Nigerian children.

  2. Oral Metformin-Ascorbic Acid Co-Administration Ameliorates Alcohol ...

    African Journals Online (AJOL)

    Oral Metformin-Ascorbic Acid Co-Administration Ameliorates Alcohol-Induced Hepatotoxicity In Rats. ... Nigerian Quarterly Journal of Hospital Medicine ... the present in vivo animal study was to determine whether metformin-ascorbic acid co-administration also prevents alcoholic hepatotoxicity in chronic alcohol exposure.

  3. Cloning and analysis of the ascorbate peroxidase gene promoter ...

    African Journals Online (AJOL)

    Ascorbate peroxidase (APX) is known to catalyze the reduction of H2O2 to water and enhance plants' tolerance in stress environment. An ascorbate peroxidase protein (BnAPX) was previously isolated from Brassica napus in our laboratory and it was located in the chloroplast. In order to clarify the physiological function of ...

  4. Isolation of an ascorbate peroxidase in Brassica napus and analysis ...

    African Journals Online (AJOL)

    USER

    2010-04-05

    Apr 5, 2010 ... domain; APX, ascorbate peroxidase; Bn-APX, Brassica napus ascorbate ... Brassica napus, which is widely grown as the oilseed crop of rape or canola, .... grew on the SD-Leu-Trp-His-Ade medium and were verified by PCR.

  5. Modelling of thermal degradation kinetics of ascorbic acid in ...

    African Journals Online (AJOL)

    Ascorbic acid (vitamin C) loss in thermally treated pawpaw and potato was modelled mathematically. Isothermal experiments in the temperature range of 50 -80 oC for the drying of pawpaw and 60 -100 oC for the blanch-drying of potato were utilized to determine the kinetics of ascorbic acid loss in both fruit and vegetable.

  6. Effect of ascorbic acid supplementation level to diets of indigenous ...

    African Journals Online (AJOL)

    All the birds were offered the same grower feed and fresh water ad libitum. Indigenous Venda hens supplemented with ascorbic acid produced chicks with improved (P<0.05) feed intake, feed conversion ratio, growth rate and live weight at 7 weeks of age. However, ascorbic acid supplementation to the diets of indigenous ...

  7. Gamma radiolysis of aqueous solution of ascorbic acid

    International Nuclear Information System (INIS)

    Loyola V, V.M.; Azamer B, J.A.; Laviada C, A.; Luna V, P.

    1977-01-01

    A preliminary study of the gamma radiolysis of a 1.13 x 10 -4 Maqueous solution of ascorbic acid is presented. It was found that dehydroascorbic acid was the principal product at doses of about 75 Krad. An increase in the dehydroascorbic acid concentration rangins from 5 to 40% was obtained, these values depend mainly on the initial ascorbic acid concentration. (author)

  8. Effect of supplemental Ascorbic acid and disturbance stress on the ...

    African Journals Online (AJOL)

    Effect of supplemental Ascorbic acid and disturbance stress on the performance of broiler chickens. ... Nigerian Journal of Animal Production ... Results showed that there were no significant interactions between dietary ascorbic acid supplementation and disturbance stress levels on any of the performance data considered.

  9. Exogenous fatty acid metabolism in bacteria.

    Science.gov (United States)

    Yao, Jiangwei; Rock, Charles O

    2017-10-01

    Bacterial type II fatty acid synthesis (FASII) is a target for novel antibiotic development. All bacteria encode for mechanisms to incorporate exogenous fatty acids, and some bacteria can use exogenous fatty acids to bypass FASII inhibition. Bacteria encode three different mechanisms for activating exogenous fatty acids for incorporation into phospholipid synthesis. Exogenous fatty acids are converted into acyl-CoA in Gammaproteobacteria such as E. coli. Acyl-CoA molecules constitute a separate pool from endogenously synthesized acyl-ACP. Acyl-CoA can be used for phospholipid synthesis or broken down by β-oxidation, but cannot be used for lipopolysaccharide synthesis. Exogenous fatty acids are converted into acyl-ACP in some Gram-negative bacteria. The resulting acyl-ACP undergoes the same fates as endogenously synthesized acyl-ACP. Exogenous fatty acids are converted into acyl-phosphates in Gram-positive bacteria, and can be used for phospholipid synthesis or become acyl-ACP. Only the order Lactobacillales can use exogenous fatty acids to bypass FASII inhibition. FASII shuts down completely in presence of exogenous fatty acids in Lactobacillales, allowing Lactobacillales to synthesize phospholipids entirely from exogenous fatty acids. Inhibition of FASII cannot be bypassed in other bacteria because FASII is only partially down-regulated in presence of exogenous fatty acid or FASII is required to synthesize essential metabolites such as β-hydroxyacyl-ACP. Certain selective pressures such as FASII inhibition or growth in biofilms can select for naturally occurring one step mutations that attenuate endogenous fatty acid synthesis. Although attempts have been made to estimate the natural prevalence of these mutants, culture-independent metagenomic methods would provide a better estimate. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  10. Formation of an ascorbate-apatite composite layer on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Atsuo [National Institute of Advanced Industrial Science and Technology (AIST), Institute for Human Science and Biomedical Engineering, Central 6, Higashi 1-1-1, Tsukuba, Ibaraki 305-8566 (Japan); Sogo, Yu [National Institute of Advanced Industrial Science and Technology (AIST), Institute for Human Science and Biomedical Engineering, Central 6, Higashi 1-1-1, Tsukuba, Ibaraki 305-8566 (Japan); Ebihara, Yuko [School of Science and Technology, Waseda University, 3-4-1 Okubo, Sinjuku-ku, Tokyo 169-8050 (Japan); Onoguchi, Masahiro [School of Science and Technology, Waseda University, 3-4-1 Okubo, Sinjuku-ku, Tokyo 169-8050 (Japan); Oyane, Ayako [National Institute of Advanced Industrial Science and Technology (AIST), Nanotechnology Research Institute, Central 4, Higashi 1-1-1, Tsukuba, Ibaraki 305-8562 (Japan); Ichinose, Noboru [School of Science and Technology, Waseda University, 3-4-1 Okubo, Sinjuku-ku, Tokyo 169-8050 (Japan)

    2007-09-15

    An ascorbate-apatite composite layer was successfully formed on NaOH- and heat-treated titanium by coprecipitating L-ascorbic acid phosphate and low-crystalline apatite in a supersaturated calcium phosphate solution at 37 {sup 0}C for 48 h. The supersaturated calcium phosphate solutions used have chemical compositions attainable by mixing infusion fluids officially approved for clinical use. The amount of immobilized L-ascorbic acid phosphate ranged from 1.0 to 2.3 {mu}g mm{sup -2}, which is most likely to be sufficient for the in vitro osteogenic differentiation of mesenchymal stem cells on titanium. Since ascorbate is important for the collagen synthesis and subsequent osteogenesis of mesenchymal stem cells, titanium coated with the ascorbate-apatite composite layer would be useful as a scaffold in bone tissue engineering and as a bone substitute.

  11. Formation of an ascorbate-apatite composite layer on titanium

    International Nuclear Information System (INIS)

    Ito, Atsuo; Sogo, Yu; Ebihara, Yuko; Onoguchi, Masahiro; Oyane, Ayako; Ichinose, Noboru

    2007-01-01

    An ascorbate-apatite composite layer was successfully formed on NaOH- and heat-treated titanium by coprecipitating L-ascorbic acid phosphate and low-crystalline apatite in a supersaturated calcium phosphate solution at 37 0 C for 48 h. The supersaturated calcium phosphate solutions used have chemical compositions attainable by mixing infusion fluids officially approved for clinical use. The amount of immobilized L-ascorbic acid phosphate ranged from 1.0 to 2.3 μg mm -2 , which is most likely to be sufficient for the in vitro osteogenic differentiation of mesenchymal stem cells on titanium. Since ascorbate is important for the collagen synthesis and subsequent osteogenesis of mesenchymal stem cells, titanium coated with the ascorbate-apatite composite layer would be useful as a scaffold in bone tissue engineering and as a bone substitute

  12. Radioprotective effects of ascorbic acid in barley seeds

    Energy Technology Data Exchange (ETDEWEB)

    Conger, B V

    1975-01-01

    Experiments were conducted to test the radioprotective effects of a naturally occurring reducing agent, ascorbic acid, on seeds (caryopses) of barley, Hordeum vulgare L. emend Lam. Seeds were soaked either before or after ..gamma.. or fission neutron irradiation in distilled water or ascorbic acid solutions ranging in concentration from 0.01 to 1.00 M. Results are reported as percentage germination, seedling height, seedling growth reduction, and (in one experiment) percent of cells with chromosome aberrations. As evidenced by both reduced germination and seedling growth, ascorbic acid was toxic when seeds were soaked for 1 hr at ambient temperature prior to irradiation and then planted immediately. When seeds were soaked in ascorbic acid before irradiation and soaked after irradiation in air-bubbled water at 0/sup 0/C for 18 hr, the toxicity disappeared, and a protective effect (which increased with increasing ascorbic acid concentration) was observed for ..gamma.. and, to a lesser extent, for neutron irradiation. Additional studies suggested that the protective effect was related to reduced hydration of the embryos of seeds soaked in ascorbic acid. Also, no radioprotective effect was observed when seeds were presoaked for 2 or 16 hr in 0.01 M ascorbic acid solutions buffered at pH 3 or pH 7. A protective effect was observed for seeds of 1.5 percent water content soaked after irradiation in an oxygen-bubbled ascorbic acid solution of 0.5 M but was not observed for seeds soaked in nitrogen-bubbled ascorbic acid. The protective effect against oxygen-dependent damage may be a result of interaction of ascorbic acid with radiation-induced free radicals.

  13. Electrochemical Sensor for Determination of Ascorbic Acid Using a 2-Chlorobenzoyl Ferrocene/Carbon Nanotube Paste Electrode

    Directory of Open Access Journals (Sweden)

    Sayed Zia Mohammadi

    2016-12-01

    Full Text Available A chemically modified carbon paste electrode with 2-chlorobenzoyl ferrocene (2CBF and carbon nanotube (2CBFCNPE was employed to study the electrocatalytic oxidation of ascorbic acid in aqueous solution using cyclic voltammetry, square wave voltammetry and chronoamperometry. The diffusion coefficient (D = 1.42 × 10-6 cm2 s-1, and the kinetic parameter such as the catalytic rate constant (k = 3.7 × 10 3 M-1 s-1 of ascorbic acid oxidation at the surface of 2CBFCNPE were determined using electrochemical approaches. It has been found that under an optimum condition (pH 4.0, the oxidation of ascorbic acid at the surface of such an electrode occurs at a potential about 85 mV less positive than that of an unmodified carbon paste electrode. Applying square wave voltammetry, in phosphate buffer solution (PBS of pH 4.0, the oxidation current increases linearly with two concentration intervals of ascorbic acid, one is 1.0 × 10-7-2.5 × 10-6 M and the other is 2.5 × 10-6-7.0 × 10-5 M. Detection limit (3δ was obtained 64.0 nM. This method was also examined for determination of ascorbic acid in some real samples.

  14. Exogenous melatonin improves Malus resistance to Marssonina apple blotch.

    Science.gov (United States)

    Yin, Lihua; Wang, Ping; Li, Mingjun; Ke, Xiwang; Li, Cuiying; Liang, Dong; Wu, Shan; Ma, Xinli; Li, Chao; Zou, Yangjun; Ma, Fengwang

    2013-05-01

    We examined whether exogenously applied melatonin could improve resistance to Marssonina apple blotch (Diplocarpon mali) by apple [Malus prunifolia (Willd.) Borkh. cv. Donghongguo]. This serious disease leads to premature defoliation in the main regions of apple production. When plants were pretreated with melatonin, resistance was increased in the leaves. We investigated the potential roles for melatonin in modulating levels of hydrogen peroxide (H2O2), as well the activities of antioxidant enzymes and pathogenesis-related proteins during these plant-pathogen interactions. Pretreatment enabled plants to maintain intracellular H2O2 concentrations at steady-state levels and enhance the activities of plant defence-related enzymes, possibly improving disease resistance. Because melatonin is safe and beneficial to animals and humans, exogenous pretreatment might represent a promising cultivation strategy to protect plants against this pathogen infection. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  15. Polarographic measurement of ascorbate washout in isolated perfused rabbit hearts

    International Nuclear Information System (INIS)

    Arts, T.; Kuikka, J.T.; Reneman, R.S.; Bassingthwaighte, J.B.

    1985-01-01

    To study the myocardial washout of ascorbate, the applicability of polarographic detection of ascorbate ions by a platinum electrode (sensitive area 0.03 mm2) was investigated, in both a calibration setup (sampling flow along the electrode: 100 microliter X s-1) and isolated, retrogradely perfused rabbit hearts. In the calibration setup at pH 7.4, the sensitivity of the electrode was 70 microA/mol. This sensitivity increased moderately with increasing pH (13%/unit pH) and increasing sampling flow rate (14% at an increase from 100 to 150 microliter X s-1). In the isolated hearts, ascorbate infused into the aorta was detected in a right ventricular drain by the electrode as well as by the use of 14 C-labeled ascorbate. Both recorded time courses were similar except for a scaling factor dependent on flow velocity. During continuous infusion the arteriovenous difference of ascorbate was 2 +/- 2% (SD), indicating a relatively low consumption of ascorbate by the isolated heart. The authors conclude that polarographic measurement of ascorbate in the coronary effluent of an isolated rabbit heart can be performed on-line and relatively easily

  16. Enhancing Lipid Stability in Irradiated Beef Mince by Oleoresins and/ or Ascorbic Acid during Chilling Storage

    International Nuclear Information System (INIS)

    Zahran, D.A.

    2008-01-01

    Lipid Oxidation, fatty acids profile and sensory properties of irradiated beef mince (2.5 kGy) treated with oleoresins (rosemary or ginger), ascorbic acid, or combination of ascorbic acid and oleoresins were investigated during 30 days of chilled storage. Thiobarbituric acid reactive substances (TBARS) as an indication of lipid oxidation, of irradiated control samples were significantly higher than those of non irradiated control and samples treated with rosemary and ginger oleoresins. By GC-MS analysis, it was found that the relative percentage of total saturated fatty acids (TSFA) increased in all treatments. However, the highest increase was recorded in irradiated control samples compared to non irradiated control samples. Beef mince samples treated with oleoresins (rosemary or ginger) had the best scores for discoloration and off odour. Thus, the addition of oleoresins (rosemary or ginger) to beef mince before irradiation could be an easily applied method to minimize oxidative degradation of irradiated meat

  17. The influence of ascorbic acid on the oxygen consumption and the heat production by the cells of wheat seedling roots with their mitochondrial electron transport chain inhibited at complexes I and III

    International Nuclear Information System (INIS)

    Gordon, L.K.; Rakhmatullina, D.F.; Ogorodnikova, T.I.; Alyabyev, A.J.; Minibayeva, F.V.; Loseva, N.L.; Mityashina, S.Y.

    2007-01-01

    The influence of exogenous ascorbic acid (AsA) on oxidative phosphorylation was studied using wheat seedling roots. Treatment of them with AsA stimulated the rates of oxygen consumption and the heat production and caused a decrease of the respiratory coefficient. The increase in respiration was prevented by inhibitors of ascorbate oxidase, diethyldithiocarbamate (DEDTC), and of cytochrome oxidase, cyanide (KCN). Exogenous AsA sharply stimulated the rate of oxygen consumption of roots when complexes I and III of the mitochondrial electron transport chain were inhibited by rotenone and antimycin A, respectively, while the rates of heat production did not change significantly. It is concluded that AsA is a potent energy substrate, which can be used in conditions of failing I and III complexes in the mitochondrial electron transport chain

  18. [Effect of exogenous sucrose on growth and active ingredient content of licorice seedlings under salt stress conditions].

    Science.gov (United States)

    Liu, Fu-zhi; Yang, Jun

    2015-11-01

    Licorice seedlings were taken as experimental materials, an experiment was conducted to study the effects of exogenous sucrose on growth and active ingredient content of licorice seedlings under NaCl stress conditions. The results of this study showed that under salt stress conditions, after adding a certain concentration of exogenous sucrose, the licorice seedlings day of relative growth rate was increasing, and this stress can be a significant weakening effect, indicating that exogenous sucrose salt stress-relieving effect. The total flavonoids and phenylalanine ammonia lyase (PAL) activity were significantly increased, the exogenous sucrose can mitigated the seedling roots under salt stress, the licorice flavonoid content in the enhanced growth was largely due to the activity of PAL an increased, when the concentration of exogenous sucrose wae 10 mmol x L(-1), PAL activity reaching a maximum, when the concentration of exogenous sucrose was 15 mmol x L(-1), PAL activity turned into a downward trend, the results indicating that this mitigation has concentration effect. After applying different concentrations of exogenous sugar, the contents of liquiritin changes with the change of flavonoids content was similar. After applying different concentrations of exogenous sucrose, the content of licorice acid under salt stress was higher than the levels were not reached during salt stress, the impact of exogenous sucrose concentration gradient of licorice acid accumulation was not obvious.

  19. Using synergistic exogenous phytohormones to enhance somatic ...

    African Journals Online (AJOL)

    Southern Forests: a Journal of Forest Science ... Eucalyptus spp. has been limited to germinated seeds, flowers, lignotubers or zygotic embryos. ... explants could be enhanced through pairing of synergistic exogenous plant growth regulators, ...

  20. Aortic wall damage in mice unable to synthesize ascorbic acid

    OpenAIRE

    Maeda, Nobuyo; Hagihara, Hiroyuki; Nakata, Yukiko; Hiller, Sylvia; Wilder, Jennifer; Reddick, Robert

    2000-01-01

    By inactivating the gene for l-gulono-γ-lactone oxidase, a key enzyme in ascorbic acid synthesis, we have generated mice that, like humans, depend on dietary vitamin C. Regular chow, containing about 110 mg/kg of vitamin C, is unable to support the growth of the mutant mice, which require l-ascorbic acid supplemented in their drinking water (330 mg/liter). Upon withdrawal of supplementation, plasma and tissue ascorbic acid levels decreased to 10–15% of normal within 2 weeks, and after 5 weeks...

  1. Visible propagation from invisible exogenous cueing.

    Science.gov (United States)

    Lin, Zhicheng; Murray, Scott O

    2013-09-20

    Perception and performance is affected not just by what we see but also by what we do not see-inputs that escape our awareness. While conscious processing and unconscious processing have been assumed to be separate and independent, here we report the propagation of unconscious exogenous cueing as determined by conscious motion perception. In a paradigm combining masked exogenous cueing and apparent motion, we show that, when an onset cue was rendered invisible, the unconscious exogenous cueing effect traveled, manifesting at uncued locations (4° apart) in accordance with conscious perception of visual motion; the effect diminished when the cue-to-target distance was 8° apart. In contrast, conscious exogenous cueing manifested in both distances. Further evidence reveals that the unconscious and conscious nonretinotopic effects could not be explained by an attentional gradient, nor by bottom-up, energy-based motion mechanisms, but rather they were subserved by top-down, tracking-based motion mechanisms. We thus term these effects mobile cueing. Taken together, unconscious mobile cueing effects (a) demonstrate a previously unknown degree of flexibility of unconscious exogenous attention; (b) embody a simultaneous dissociation and association of attention and consciousness, in which exogenous attention can occur without cue awareness ("dissociation"), yet at the same time its effect is contingent on conscious motion tracking ("association"); and (c) underscore the interaction of conscious and unconscious processing, providing evidence for an unconscious effect that is not automatic but controlled.

  2. Is Money Really Exogenous? Testing for Weak Exogeneity in Swiss Money Demand.

    OpenAIRE

    Fischer, Andreas M

    1993-01-01

    Although exogeneity is often associated with controllable policy variables, Engle, Hendry, and Richard (1983) show that the one condition is neither necessary nor sufficient for the other. Whether variables such as monetary aggregates are (weakly) exogenous depends on the conditioning properties of the data generating process. Testing exogeneity claims represents an important step in analyzing money demand functions. Although Switzerland adheres to fairly strict monetarist prescriptions, we r...

  3. Effect of 10% sodium ascorbate on Streptococcus mutans ...

    African Journals Online (AJOL)

    USER

    2010-08-16

    Aug 16, 2010 ... After sterilization of the intact enamel surfaces with UV light, the specimens .... the bleaching agent and sodium ascorbate has led to a maximum amount of .... Radcliffe CE, Lamp R, Blinkhorn AS, Drucker DB (2003). Effect of.

  4. Effects of Ascorbic Acid on Reproductive Functions of Male Wistar ...

    African Journals Online (AJOL)

    In conclusion, ascorbic acid supplement may suppress nicotine toxic effects on reproductive functions in male rats. ... et al., 2007). Nicotine is rapidly absorbed by the brain .... difference (LSD) test. p<0.05 was considered significant. Statistical ...

  5. Radiation protection by ascorbic acid in sodium alginate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Aliste, A.J.; Mastro, N.L. Del [Center of Radiation Technology, IPEN/CNEN/SP, University City, 05508-000 Sao Paulo (Brazil)]. E-mail: ajaliste@ipen.br

    2004-07-01

    Alginates are gelling hydrocolloids extracted from brown seaweed used widely in the nourishing and pharmaceutical industries. As alginic acid gellification retard food entrance in the stomach alginate is an additive used in diets. The objective of this work was to study the protective action of the ascorbic acid in alginate solutions against the action of {sup 60} Co gamma radiation. One % (w/v) solutions of alginate had been used and concentrations of ascorbic acid varied from 0 to 2.5% (w/v). The solutions were irradiated with doses up to 10 kGy. Viscosity/dose relationship and the p H of the solutions at 25 Centigrade were determined. Ascorbic acid behaved as an antioxidant against radiation oxidative shock in this model system of an irradiated viscous solution. Besides its radiation protective role on alginate solutions ascorbic acid promoted a viscosity increase in the range of concentrations employed. (Author)

  6. Lead induced dyslipidemia: The comparative effects of ascorbate ...

    African Journals Online (AJOL)

    R.N. UGBAJA

    2013-04-10

    Apr 10, 2013 ... Key words: Ascorbate, chelating agents, dyslipidemia, lead exposure, plumbism. .... elements like iron, zinc, calcium and a host of other divalent elements in ..... cholesterol synthesis and transport pathways may be adversely ...

  7. Effects of Ascorbic Acid on Reproductive Functions of Male Wistar ...

    African Journals Online (AJOL)

    Effects of Ascorbic Acid on Reproductive Functions of Male Wistar Rats Exposed to Nicotine. ... smoke, and its effects on male reproductive system and fertility are well documented. ... The drugs were orally administered for thirty-five days.

  8. Selective response of dopamine in the presence of ascorbic acid ...

    African Journals Online (AJOL)

    Selective response of dopamine in the presence of ascorbic acid and uric acid at gold nanoparticles and multi-walled carbon nanotubes grafted with ethylene diamine tetraacetic acid modified electrode.

  9. Radiation protection by ascorbic acid in sodium alginate solutions

    International Nuclear Information System (INIS)

    Aliste, A.J.; Mastro, N.L. Del

    2004-01-01

    Alginates are gelling hydrocolloids extracted from brown seaweed used widely in the nourishing and pharmaceutical industries. As alginic acid gellification retard food entrance in the stomach alginate is an additive used in diets. The objective of this work was to study the protective action of the ascorbic acid in alginate solutions against the action of 60 Co gamma radiation. One % (w/v) solutions of alginate had been used and concentrations of ascorbic acid varied from 0 to 2.5% (w/v). The solutions were irradiated with doses up to 10 kGy. Viscosity/dose relationship and the p H of the solutions at 25 Centigrade were determined. Ascorbic acid behaved as an antioxidant against radiation oxidative shock in this model system of an irradiated viscous solution. Besides its radiation protective role on alginate solutions ascorbic acid promoted a viscosity increase in the range of concentrations employed. (Author)

  10. Macrokinetics of magnesium sulfite oxidation inhibited by ascorbic acid

    International Nuclear Information System (INIS)

    Lidong, Wang; Yongliang, Ma; Wendi, Zhang; Qiangwei, Li; Yi, Zhao; Zhanchao, Zhang

    2013-01-01

    Graphical abstract: Ascorbic acid is used as an inhibitor to retard the oxidation rate of magnesium sulfite. It shows that the oxidation rate would decrease greatly with the rise of initial ascorbic acid concentration, which provides a useful reference for sulfite recovery in magnesia desulfurization. -- Highlights: • We studied the kinetics of magnesium sulfite oxidation inhibited by ascorbic acid. • The oxidation process was simulated by a three-phase model and proved by HPLC–MS. • We calculated the kinetic parameters of intrinsic oxidation of magnesium sulfite. -- Abstract: Magnesia flue gas desulfurization is a promising process for small to medium scale industrial coal-fired boilers in order to reduce sulfur dioxide emissions, in which oxidation control of magnesium sulfite is of great importance for the recycling of products. Effects of four inhibitors were compared by kinetic experiments indicating that ascorbic acid is the best additive, which retards the oxidation process of magnesium sulfite in trace presence. The macrokinetics of magnesium sulfite oxidation inhibited by ascorbic acid were studied. Effects of the factors, including ascorbic acid concentration, magnesium sulfite concentration, oxygen partial pressure, pH, and temperature, were investigated in a stirred reactor with bubbling. The results show that the reaction rate is −0.55 order in ascorbic acid, 0.77 in oxygen partial pressure, and zero in magnesium sulfite concentration, respectively. The apparent activation energy is 88.0 kJ mol −1 . Integrated with the kinetic model, it is concluded that the oxidation rate of magnesium sulfite inhibited by ascorbic acid is controlled by the intrinsic chemical reaction. The result provides a useful reference for sulfite recovery in magnesia desulfurization

  11. Nitric Oxide in Plants: The Roles of Ascorbate and Hemoglobin

    Science.gov (United States)

    Wang, Xiaoguang; Hargrove, Mark S.

    2013-01-01

    Ascorbic acid and hemoglobins have been linked to nitric oxide metabolism in plants. It has been hypothesized that ascorbic acid directly reduces plant hemoglobin in support of NO scavenging, producing nitrate and monodehydroascorbate. In this scenario, monodehydroascorbate reductase uses NADH to reduce monodehydroascorbate back to ascorbate to sustain the cycle. To test this hypothesis, rates of rice nonsymbiotic hemoglobin reduction by ascorbate were measured directly, in the presence and absence of purified rice monodehydroascorbate reductase and NADH. Solution NO scavenging was also measured methodically in the presence and absence of rice nonsymbiotic hemoglobin and monodehydroascorbate reductase, under hypoxic and normoxic conditions, in an effort to gauge the likelihood of these proteins affecting NO metabolism in plant tissues. Our results indicate that ascorbic acid slowly reduces rice nonsymbiotic hemoglobin at a rate identical to myoglobin reduction. The product of the reaction is monodehydroascorbate, which can be efficiently reduced back to ascorbate in the presence of monodehydroascorbate reductase and NADH. However, our NO scavenging results suggest that the direct reduction of plant hemoglobin by ascorbic acid is unlikely to serve as a significant factor in NO metabolism, even in the presence of monodehydroascorbate reductase. Finally, the possibility that the direct reaction of nitrite/nitrous acid and ascorbic acid produces NO was measured at various pH values mimicking hypoxic plant cells. Our results suggest that this reaction is a likely source of NO as the plant cell pH drops below 7, and as nitrite concentrations rise to mM levels during hypoxia. PMID:24376554

  12. Exogenous abscisic acid alleviates zinc uptake and accumulation in Populus × canescens exposed to excess zinc.

    Science.gov (United States)

    Shi, Wen-Guang; Li, Hong; Liu, Tong-Xian; Polle, Andrea; Peng, Chang-Hui; Luo, Zhi-Bin

    2015-01-01

    A greenhouse experiment was conducted to study whether exogenous abscisic acid (ABA) mediates the responses of poplars to excess zinc (Zn). Populus × canescens seedlings were treated with either basal or excess Zn levels and either 0 or 10 μm ABA. Excess Zn led to reduced photosynthetic rates, increased Zn accumulation, induced foliar ABA and salicylic acid (SA), decreased foliar gibberellin (GA3 ) and auxin (IAA), elevated root H2 O2 levels, and increased root ratios of glutathione (GSH) to GSSG and foliar ratios of ascorbate (ASC) to dehydroascorbate (DHA) in poplars. While exogenous ABA decreased foliar Zn concentrations with 7 d treatments, it increased levels of endogenous ABA, GA3 and SA in roots, and resulted in highly increased foliar ASC accumulation and ratios of ASC to DHA. The transcript levels of several genes involved in Zn uptake and detoxification, such as yellow stripe-like family protein 2 (YSL2) and plant cadmium resistance protein 2 (PCR2), were enhanced in poplar roots by excess Zn but repressed by exogenous ABA application. These results suggest that exogenous ABA can decrease Zn concentrations in P. × canescens under excess Zn for 7 d, likely by modulating the transcript levels of key genes involved in Zn uptake and detoxification. © 2014 John Wiley & Sons Ltd.

  13. Studies on the biological oxidation - The oxidation of ascorbic acid (vitamin C) in biological fluids

    OpenAIRE

    Guzmán Barrón, E. S.; Guzmán Barrón, Alberto; Klemperer, Friedrich

    2014-01-01

    Biological fluids can be divided according to their behavior toward ascorbic acid into two groups: those having an inhibitory mechanism that protects the ascorbic acid oxidation, and those lacking this mechanism. Animal fluids and some of vegetable origin (those containing dosables amounts of ascorbic acid) corresponding to the first group. Ascorbic acid is protected from oxidation in the fluids by the action of copper catalyst. Fluids from plants (those that contain very little ascorbic acid...

  14. Validation of ascorbic acid tablets of national production by igh-performance liquid chromatography method

    International Nuclear Information System (INIS)

    Rodriguez Hernandez, Yaslenis; Suarez Perez, Yania; Izquierdo Castro, Idalberto

    2009-01-01

    We validate an analytical method by high-performance liquid chromatography to determine ascorbic acid proportion in vitamin C tablets, which was designed as an alternative method to quality control and to follow-up of active principle chemical stability, since official techniques to quality control of ascorbic acid in tablets are not selective with degradation products. Method was modified according to that reported in USP 28, 2005 for analysis of injectable product. We used a RP-18 column of 250 x 4.6 mm 5 μm with a UV detector to 245 nm. Its validation was necessary for both objectives, considering parameters required for methods of I and II categories. This method was enough linear, exact, and precise in the rank of 100-300 μg/mL. Also, it was selective with remaining components of matrix and with the possible degradation products achieved in stressing conditions. Detection and quantification limits were estimated. When method was validated it was applied to ascorbic acid quantification in two batches of expired tablets and we detected a marked influence of container in active degradation principle after 12 months at room temperature. (Author)

  15. Genotoxicity and oxidative stress of microwave radiation role of ascorbic acid

    International Nuclear Information System (INIS)

    Desouky, O.S.; Abdel Karim, M.A.; Deiaa El Deen, D.A.; Nayal, N.A.

    2005-01-01

    Radiofrequency fields and especially microwaves are very important part of electromagnetic spectrum that can produce generations of reactive oxygen species, and thus can affect DNA and cause chromosomal aberrations. So this effect can be diminished by the supplement of an antioxidant such as ascorbic acid. In this study, the proposed protective role of ascorbic acid was tested against the EMF induced chromosomal aberrations and lipid peroxidation. The present study proved that EMF had a clastogenic effect on the bone marrow cells of mice, either with the exposure to EMF; 950 MHz or frequency EMF; 2450 MHz. This effect was evidenced by structural and numerical chromosomal aberrations. The study also proved that EMF had an effect on oxidative stress, evidenced by increase in the level of lipid peroxide, in a dose dependent manner. So, the mechanism of EMF induced chromosomal aberrations can be explained by this oxidative stress induced by EMF exposure. The present study showed that ascorbic acid had a protective effect against both EMF induced chromosomal aberrations and oxidative stress, when it is applied concomitantly with EMF exposure either at frequency of 950 MHz or 2450 MHz. this is evident by decreases in the level of lipid peroxide and decrease in chromosomal aberrations

  16. Modeling the degradation kinetics of ascorbic acid.

    Science.gov (United States)

    Peleg, Micha; Normand, Mark D; Dixon, William R; Goulette, Timothy R

    2018-06-13

    Most published reports on ascorbic acid (AA) degradation during food storage and heat preservation suggest that it follows first-order kinetics. Deviations from this pattern include Weibullian decay, and exponential drop approaching finite nonzero retention. Almost invariably, the degradation rate constant's temperature-dependence followed the Arrhenius equation, and hence the simpler exponential model too. A formula and freely downloadable interactive Wolfram Demonstration to convert the Arrhenius model's energy of activation, E a , to the exponential model's c parameter, or vice versa, are provided. The AA's isothermal and non-isothermal degradation can be simulated with freely downloadable interactive Wolfram Demonstrations in which the model's parameters can be entered and modified by moving sliders on the screen. Where the degradation is known a priori to follow first or other fixed order kinetics, one can use the endpoints method, and in principle the successive points method too, to estimate the reaction's kinetic parameters from considerably fewer AA concentration determinations than in the traditional manner. Freeware to do the calculations by either method has been recently made available on the Internet. Once obtained in this way, the kinetic parameters can be used to reconstruct the entire degradation curves and predict those at different temperature profiles, isothermal or dynamic. Comparison of the predicted concentration ratios with experimental ones offers a way to validate or refute the kinetic model and the assumptions on which it is based.

  17. Ascorbate regulates haematopoietic stem cell function and leukaemogenesis.

    Science.gov (United States)

    Agathocleous, Michalis; Meacham, Corbin E; Burgess, Rebecca J; Piskounova, Elena; Zhao, Zhiyu; Crane, Genevieve M; Cowin, Brianna L; Bruner, Emily; Murphy, Malea M; Chen, Weina; Spangrude, Gerald J; Hu, Zeping; DeBerardinis, Ralph J; Morrison, Sean J

    2017-09-28

    Stem-cell fate can be influenced by metabolite levels in culture, but it is not known whether physiological variations in metabolite levels in normal tissues regulate stem-cell function in vivo. Here we describe a metabolomics method for the analysis of rare cell populations isolated directly from tissues and use it to compare mouse haematopoietic stem cells (HSCs) to restricted haematopoietic progenitors. Each haematopoietic cell type had a distinct metabolic signature. Human and mouse HSCs had unusually high levels of ascorbate, which decreased with differentiation. Systemic ascorbate depletion in mice increased HSC frequency and function, in part by reducing the function of Tet2, a dioxygenase tumour suppressor. Ascorbate depletion cooperated with Flt3 internal tandem duplication (Flt3 ITD ) leukaemic mutations to accelerate leukaemogenesis, through cell-autonomous and possibly non-cell-autonomous mechanisms, in a manner that was reversed by dietary ascorbate. Ascorbate acted cell-autonomously to negatively regulate HSC function and myelopoiesis through Tet2-dependent and Tet2-independent mechanisms. Ascorbate therefore accumulates within HSCs to promote Tet activity in vivo, limiting HSC frequency and suppressing leukaemogenesis.

  18. Ascorbic acid transport and accumulation in human neutrophils

    International Nuclear Information System (INIS)

    Washko, P.; Rotrosen, D.; Levine, M.

    1989-01-01

    The transport, accumulation, and distribution of ascorbic acid were investigated in isolated human neutrophils utilizing a new ascorbic acid assay, which combined the techniques of high performance liquid chromatography and coulometric electrochemical detection. Freshly isolated human neutrophils contained 1.0-1.4 mM ascorbic acid, which was localized greater than or equal to 94% to the cytosol, was not protein bound, and was present only as ascorbic acid and not as dehydroascorbic acid. Upon addition of ascorbic acid to the extracellular medium in physiologic amounts, ascorbic acid was accumulated in neutrophils in millimolar concentrations. Accumulation was mediated by a high affinity and a low affinity transporter; both transporters were responsible for maintenance of concentration gradients as large as 50-fold. The high affinity transporter had an apparent Km of 2-5 microns by Lineweaver-Burk and Eadie-Hofstee analyses, and the low affinity transporter had an apparent Km of 6-7 mM by similar analyses. Each transporter was saturable and temperature dependent. In normal human blood the high affinity transporter should be saturated, whereas the low affinity transporter should be in its linear phase of uptake

  19. Ascorbic acid deficiency in patients with lichen planus.

    Science.gov (United States)

    Nicolae, Ilinca; Mitran, Cristina Iulia; Mitran, Madalina Irina; Ene, Corina Daniela; Tampa, Mircea; Georgescu, Simona Roxana

    2017-01-01

    Recent studies have highlighted the role of oxidative stress in the pathogenesis of lichen planus (LP). In the present study, the interest of the authors is focused on the investigation of ascorbic acid status in patients with LP and identification of parameters that might influence the level of this vitamin. We analyzed the level of urinary ascorbic acid (reflectometric method) in 77 patients with LP (cutaneous LP (CLP)-49 cases; oral LP (OLP)-28 cases) and 50 control subjects. The evaluation of all participants included clinical examination and laboratory and imaging tests. Compared to the control group (19.82 mg/dl) the level of ascorbic acid was significantly lower both in patients with CLP (8.47 mg/dl, p = 0.001) and in those with OLP (8.04 mg/dl, p = 0.001). In patients with LP it was found that the deficiency of ascorbic acid increases with age (r = -0.318, p = 0.032). The urinary concentrations of ascorbic acid were significantly lower in patients with LP associated with infections compared to patients with LP without infections. The urinary ascorbic acid level may be a useful parameter in identifying patients with LP who are at risk of developing viral or bacterial infections.

  20. Antagonism of ascorbate against the radioprotective action of cysteamine

    Energy Technology Data Exchange (ETDEWEB)

    Naeslund, M; Ehrenberg, L; Djalali-Behzad, G [Stockholm Univ. (Sweden). Radiobiologiska Institutionen

    1976-07-01

    An investigation has been carried out into the interaction of cysteamine (MEA) and ascorbate on the radiosensitivity of E.coli, with painstaking removal of autoxidation products from glassware. Trace amounts of copper could be effectively removed, and the influence of small amounts of iron contaminating the analytical grade phosphate was assessed. The bacteria were exposed to MEA and/or ascorbate for 1 hour at 37/sup 0/C, irradiation with 42 or 58 krad of /sup 60/Co ..gamma..rays taking place 30 to 40 minutes after the additions. Survival studies demonstrated the reversion of a major fraction of the radioprotective action of MEA (2 or 6 mM) by ascorbate (5 mM) simultaneously present in the medium. Net RNA synthesis, determined by the incorporation of /sup 3/H-uridine, was suppressed by MEA and this was partly reversed by ascorbate. The irradiation of bacterium suspensions containing MEA and ascorbate was found to provoke a conspicuous stimulation of RNA synthesis above the level of unirradiated parallel samples. The effects of some oxidizing treatments (dehydroascorbic acid, hydrogen peroxide, 3.6 ..mu..M FeSO/sub 4/ or 1 ..mu..M CuSO/sub 4/) together with MEA were also studied. Possible mechanisms for the ability of ascorbate to counteract the radioprotective action of MEA are discussed, and the implication of monodehydroascorbate formed during irradiation is suggested.

  1. Stimulation of matrix formation in rabbit chondrocyte cultures by ascorbate. 1. Effect of ascorbate analogs and beta-aminopropionitrile.

    Science.gov (United States)

    Wright, G C; Wei, X Q; McDevitt, C A; Lane, B P; Sokoloff, L

    1988-01-01

    The most consistent effects of 0.2 mM L-ascorbate on monolayer cultures of rabbit articular chondrocytes were a diversion of incorporated radiosulfate into a pericellular matrix and enhancement of cell proliferation. Only with certain batches of fetal bovine serum (FBS) was there a cell-for-cell increase of proteoglycan synthesis. These actions increased as the cell inoculum rose from 0.5 to 2 x 10(5) cells/T25 flask. Maximal effects of ascorbate and D-isoascorbate were found over a range of 0.05-0.2 mM. L-Dehydroascorbic acid was less effective than either, and no stimulatory action was exerted by L-cysteine, glutathione, dithiothreitol, methylene blue, or phenazine methosulfate. Ascorbate increased the hypro:pro ratio of newly synthesized proteins. beta-Aminopropionitrile (1 mM) reduced the proportion of [3H]hydroxyproline and [35S]O4-proteoglycans in the ascorbate-supplemented matrix 31 and 7%, respectively. In corresponding electronmicrographs, the number of pericellular filaments was reduced. We conclude: (a) Ascorbate has a general anabolic effect on chondrocytes in culture and enhances matrix assembly through mechanisms other than its redox function; (b) deposition of proteoglycans in the matrix is not simply the result of mechanical entrapment by allysine- or hydroxyallysine-derived cross-linking of collagen; and (c) contradictory reports on the subject result from variations in the serum employed, inoculum density, and concentration of ascorbate.

  2. Endogenous vs. exogenous regulations in the commons

    DEFF Research Database (Denmark)

    Abatayo, Anna Lou; Lynham, John

    2016-01-01

    It is widely believed that there is strong experimental evidence to support the idea that exogenously imposed regulations crowd out the intrinsic motivations of common pool resource (CPR) users to refrain from over-harvesting. We introduce a novel experimental design that attempts to disentangle...... potential confounds in previous experiments. A key feature of our experimental design is to have the exact same regulations chosen endogenously as those that are imposed exogenously. When we compare the same regulations chosen endogenously to those externally imposed, we observe no differences in extraction...... endogenous regulations with communication and exogenous regulations without communication. Our results suggest that externally imposed regulations do not crowd out intrinsic motivations in the lab and they confirm that communication facilitates cooperation to reduce extraction....

  3. Development of a universal RNA beacon for exogenous gene detection.

    Science.gov (United States)

    Guo, Yuanjian; Lu, Zhongju; Cohen, Ira Stephen; Scarlata, Suzanne

    2015-05-01

    Stem cell therapy requires a nontoxic and high-throughput method to achieve a pure cell population to prevent teratomas that can occur if even one cell in the implant has not been transformed. A promising method to detect and separate cells expressing a particular gene is RNA beacon technology. However, developing a successful, specific beacon to a particular transfected gene can take months to develop and in some cases is impossible. Here, we report on an off-the-shelf universal beacon that decreases the time and cost of applying beacon technology to select any living cell population transfected with an exogenous gene. ©AlphaMed Press.

  4. Role of ascorbic acid and α tocopherol in alleviating salinity stress on flax plant (Linum usitatissimum L.

    Directory of Open Access Journals (Sweden)

    Mervat Sh. Sadak

    2014-03-01

    Full Text Available Salinity is one of the environmental challenges in the world affecting on several physiological processes and the most limiting factor of plant productivity and quality. Two pot experiments were conducted at the wire house of National Research Centre, Cairo, Egypt during two successive seasons of 2010/2011 and 2011/2012 to assess the efficiency of two antioxidant vitamins (ascorbic acid at 1.13 and 2.27 mM or α tocopherol at 0.46 and 0.93 mM and/or salinity stress at (0.0, 3.08, 6.16, 9.23 ds/m on photosynthetic pigments, protein, carbohydrate, minerals, oil contents and yield as well as fatty acids composition of the yielded oils of three flax cultivars (Sakha 3, Giza 8 and Ariane. The data revealed that salinity stress caused significant and gradual decreases in total photosynthetic pigments, polysaccharides, total carbohydrates, total proteins and the uptake of Mg, K, Ca and P in the leaves of three flax cultivars with increasing salinity levels (3.08, 6.16, 9.23 ds/m. Otherwise, significant and gradual increase appeared in both Na and Cl. Ascorbic acid and α tocopherol at different concentrations caused significant increases in photosynthetic pigments, total carbohydrates and protein contents in the leaves of flax plants irrigated either with tap water or saline solution as compared with their corresponding controls. Exogenous application of ascorbic and α tocopherol at different concentrations exhibited decreases in Na and Cl whereas increases appeared in Mg, K, Ca and P relative to their corresponding control. Ascorbic acid (1.13 and 2.27 mM and α tocopherol (0.46 and 0.93 mM caused marked increases in yield and yield attributes of three flax cultivars either in plants irrigated with tap water or saline solution as compared to corresponding control. Ascorbic acid effects were more pronounced than α tocopherol effects. In addition, the higher level of two vitamins was more pronounced than the lower level. Regarding plants irrigated

  5. Characteristics of exogenous carbon monoxide deliveries

    Directory of Open Access Journals (Sweden)

    Hui-jun Hu

    2016-01-01

    Full Text Available Carbon monoxide (CO has long been considered an environmental pollutant and a poison. Exogenous exposure to amounts of CO beyond the physiologic level of the body can result in a protective or adaptive response. However, as a gasotransmitter, endogenous CO is important for multiple physiologic functions. To date, at least seven distinct methods of delivering CO have been utilized in animal and clinical studies. In this mini-review, we summarize the exogenous CO delivery methods and compare their advantages and disadvantages.

  6. Phase I evaluation of intravenous ascorbic acid in combination with gemcitabine and erlotinib in patients with metastatic pancreatic cancer.

    Directory of Open Access Journals (Sweden)

    Daniel A Monti

    Full Text Available Preclinical data support further investigation of ascorbic acid in pancreatic cancer. There are currently insufficient safety data in human subjects, particularly when ascorbic acid is combined with chemotherapy.14 subjects with metastatic stage IV pancreatic cancer were recruited to receive an eight week cycle of intravenous ascorbic acid (three infusions per week, using a dose escalation design, along with standard treatment of gemcitabine and erlotinib. Of 14 recruited subjects enrolled, nine completed the study (three in each dosage tier. There were fifteen non-serious adverse events and eight serious adverse events, all likely related to progression of disease or treatment with gemcitabine or erlotinib. Applying RECIST 1.0 criteria, seven of the nine subjects had stable disease while the other two had progressive disease.These initial safety data do not reveal increased toxicity with the addition of ascorbic acid to gemcitabine and erlotinib in pancreatic cancer patients. This, combined with the observed response to treatment, suggests the need for a phase II study of longer duration.Clinicaltrials.gov NCT00954525.

  7. Effects of ascorbic acid, salt, lemon juice, and honey on drying kinetics and sensory characteristic of dried mango

    Directory of Open Access Journals (Sweden)

    E. E. Abano

    2013-01-01

    Full Text Available The effects of ascorbic acid, salt solution, lemon juice, and honey pretreatment on the drying kinetics and sensory characteristics were studied. Pretreatments used affected the effective moisture diffusivity and rehydration properties of the dried mangoes. The effective moisture diffusivity values were 2.22 × 10-10 m2/s for ascorbic acid, 1.80 × 10-10 m2/s for salt solution, 2.01 × 10-10 m2/s for lemon juice, 1.93 × 10-10 m2/s for honey pretreated mangoes, and 2.31 × 10-10 m2/s for the control slices. Pretreatments enhanced the drying rate potential of mangoes. Among the thin-layer drying models fitted to the experimental data, the Middil model gave the best fit. The ascorbic acid pretreated samples were the best while the salt solution ones were the poorest with respect to reconstitution capacity. Consumer studies for overall preference for taste, colour, texture, flavour and chewiness of the dried products revealed that there was a higher preference for honey pretreated dried samples followed by the ascorbic acid, control, lemon juice, and salt solution pretreated samples. The results demonstrate that these pretreatments can be applied to enhance the moisture transport during drying and the quality of the dried products.

  8. Antagonism between abscisic acid and gibberellins is partially mediated by ascorbic acid during seed germination in rice.

    Science.gov (United States)

    Ye, Nenghui; Zhang, Jianhua

    2012-05-01

    The antagonism between abscisic acid (ABA) and gibberellin (GA) plays a key role in controlling seed germination, but the mechanism of antagonism during this process is not known. In the associated study, we investigated the relationship among ABA, reactive oxygen species (ROS), ascorbic acid (ASC) and GA during rice seed germination. ROS production is reduced by ABA, which hence results in decreasing ASC accumulation during imbibition. GA accumulation was also suppressed by a reduced ROS and ASC level, whereas application of exogenous ASC can partially rescue seed germination from ABA treatment. Further results show that production of ASC, which acts as a substrate in GA biosynthesis, was significantly inhibited by lycorine which thus suppressed the accumulation of GA. Consequently, expression of GA biosynthesis genes was suppressed by the low levels of ROS and ASC in ABA-treated seeds. These studies reveal a new role for ASC in mediating the antagonism between ABA and GA during seed germination in rice.

  9. Assessing of distribution, mobility and bioavailability of exogenous Pb in agricultural soils using isotopic labeling method coupled with BCR approach

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhi-Yong, E-mail: zhyhuang@jmu.edu.cn [College of Bioengineering, Jimei University, Xiamen 361021 (China); Xie, Hong [College of Bioengineering, Jimei University, Xiamen 361021 (China); Shandong Vocational Animal Science and Veterinary College, Weifang 261061 (China); Cao, Ying-Lan [College of Bioengineering, Jimei University, Xiamen 361021 (China); Cai, Chao [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Zhang, Zhi [College of Bioengineering, Jimei University, Xiamen 361021 (China)

    2014-02-15

    Highlights: • Large amounts of exogenous Pb were found to distribute in reducible fractions. • Very few of exogenous Pb were found to distribute in acid-extractable fractions. • More than 60% of exogenous Pb in rhizosphere soils lost after planting. • Isotopic labeling method and SEP enable to explore Pb bioavailability in soil. -- Abstract: The contamination of Pb in agricultural soils is one of the most important ecological problems, which potentially results in serious health risk on human health through food chain. Hence, the fate of exogenous Pb contaminated in agricultural soils is needed to be deeply explored. By spiking soils with the stable enriched isotopes of {sup 206}Pb, the contamination of exogenous Pb{sup 2+} ions in three agricultural soils sampled from the estuary areas of Jiulong River, China was simulated in the present study, and the distribution, mobility and bioavailability of exogenous Pb in the soils were investigated using the isotopic labeling method coupled with a four-stage BCR (European Community Bureau of Reference) sequential extraction procedure. Results showed that about 60–85% of exogenous Pb was found to distribute in reducible fractions, while the exogenous Pb in acid-extractable fractions was less than 1.0%. After planting, the amounts of exogenous Pb presenting in acid-extractable, reducible and oxidizable fractions in rhizospheric soils decreased by 60–66%, in which partial exogenous Pb was assimilated by plants while most of the metal might transfer downward due to daily watering and applying fertilizer. The results show that the isotopic labeling technique coupled with sequential extraction procedures enables us to explore the distribution, mobility and bioavailability of exogenous Pb contaminated in soils, which may be useful for the further soil remediation.

  10. Assessing of distribution, mobility and bioavailability of exogenous Pb in agricultural soils using isotopic labeling method coupled with BCR approach

    International Nuclear Information System (INIS)

    Huang, Zhi-Yong; Xie, Hong; Cao, Ying-Lan; Cai, Chao; Zhang, Zhi

    2014-01-01

    Highlights: • Large amounts of exogenous Pb were found to distribute in reducible fractions. • Very few of exogenous Pb were found to distribute in acid-extractable fractions. • More than 60% of exogenous Pb in rhizosphere soils lost after planting. • Isotopic labeling method and SEP enable to explore Pb bioavailability in soil. -- Abstract: The contamination of Pb in agricultural soils is one of the most important ecological problems, which potentially results in serious health risk on human health through food chain. Hence, the fate of exogenous Pb contaminated in agricultural soils is needed to be deeply explored. By spiking soils with the stable enriched isotopes of 206 Pb, the contamination of exogenous Pb 2+ ions in three agricultural soils sampled from the estuary areas of Jiulong River, China was simulated in the present study, and the distribution, mobility and bioavailability of exogenous Pb in the soils were investigated using the isotopic labeling method coupled with a four-stage BCR (European Community Bureau of Reference) sequential extraction procedure. Results showed that about 60–85% of exogenous Pb was found to distribute in reducible fractions, while the exogenous Pb in acid-extractable fractions was less than 1.0%. After planting, the amounts of exogenous Pb presenting in acid-extractable, reducible and oxidizable fractions in rhizospheric soils decreased by 60–66%, in which partial exogenous Pb was assimilated by plants while most of the metal might transfer downward due to daily watering and applying fertilizer. The results show that the isotopic labeling technique coupled with sequential extraction procedures enables us to explore the distribution, mobility and bioavailability of exogenous Pb contaminated in soils, which may be useful for the further soil remediation

  11. Low brain ascorbic acid increases susceptibility to seizures in mouse models of decreased brain ascorbic acid transport and Alzheimer's disease.

    Science.gov (United States)

    Warner, Timothy A; Kang, Jing-Qiong; Kennard, John A; Harrison, Fiona E

    2015-02-01

    Seizures are a known co-occurring symptom of Alzheimer's disease, and they can accelerate cognitive and neuropathological dysfunction. Sub-optimal vitamin C (ascorbic acid) deficiency, that is low levels that do not lead the sufferer to present with clinical signs of scurvy (e.g. lethargy, hemorrhage, hyperkeratosis), are easily obtainable with insufficient dietary intake, and may contribute to the oxidative stress environment of both Alzheimer's disease and epilepsy. The purpose of this study was to test whether mice that have diminished brain ascorbic acid in addition to carrying human Alzheimer's disease mutations in the amyloid precursor protein (APP) and presenilin 1 (PSEN1) genes, had altered electrical activity in the brain (electroencephalography; EEG), and were more susceptible to pharmacologically induced seizures. Brain ascorbic acid was decreased in APP/PSEN1 mice by crossing them with sodium vitamin C transporter 2 (SVCT2) heterozygous knockout mice. These mice have an approximately 30% decrease in brain ascorbic acid due to lower levels of SVCT2 that supplies the brain with ASC. SVCT2+/-APP/PSEN1 mice had decreased ascorbic acid and increased oxidative stress in brain, increased mortality, faster seizure onset latency following treatment with kainic acid (10 mg/kg i.p.), and more ictal events following pentylenetetrazol (50 mg/kg i.p.) treatment. Furthermore, we report the entirely novel phenomenon that ascorbic acid deficiency alone increased the severity of kainic acid- and pentylenetetrazol-induced seizures. These data suggest that avoiding ascorbic acid deficiency may be particularly important in populations at increased risk for epilepsy and seizures, such as Alzheimer's disease. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Green reduction of graphene oxide by ascorbic acid

    Science.gov (United States)

    Khosroshahi, Zahra; Kharaziha, Mahshid; Karimzadeh, Fathallah; Allafchian, Alireza

    2018-01-01

    Graphene, a single layer of sp2-hybridized carbon atoms in a hexagonal (two-dimensional honey-comb) lattice, has attracted strong scientific and technological interest due to its novel and excellent optical, chemical, electrical, mechanical and thermal properties. The solution-processable chemical reduction of Graphene oxide (GO is considered as the most favorable method regarding mass production of graphene. Generally, the reduction of GO is carried out by chemical approaches using different reductants such as hydrazine and sodium borohydride. These components are corrosive, combustible and highly toxic which may be dangerous for personnel health and the environment. Hence, these reducing agents are not promising choice for reducing of graphene oxide (GO). As a consequence, it is necessary for further development and optimization of eco-friendly, natural reducing agent for clean and effective reduction of GO. Ascorbic acid, an eco-friendly and natural reducing agents, having a mild reductive ability and nontoxic property. So, the aim of this research was to green synthesis of GO with ascorbic acid. For this purpose, the required amount of NaOH and ascorbic acid were added to GO solution (0.5 mg/ml) and were heated at 95 °C for 1 hour. According to the X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and electrochemical results, GO were reduced with ascorbic acid like hydrazine with better electrochemical properties and ascorbic acid is an ideal substitute for hydrazine in the reduction of graphene oxide process.

  13. Ascorbic Acid Contents in Chili Peppers (Capsicum L.

    Directory of Open Access Journals (Sweden)

    Owk ANIEL KUMAR

    2009-12-01

    Full Text Available The genus Capsicum commonly known as chili pepper is a major spice crop and is almost cosmopolitan in distribution. The nutritive value of chili pepper is largely determined by ascorbic acid content. The fruits at five ripening stages viz., (M1, M2, M3, M4 and M5 from seventeen cultivars of Capsicum annuum L and one cultivar of Capsicum frutescens L were analyzed for ascorbic acid content. Among eighteen genotypes the C. annuum var. IC: 119262(CA2 showed higher ascorbic acid content (mg/100g FW i.e., 208.00.68 (M1, 231.00.66 (M2, 280.00.31 (M3, 253.00.34 (M4 and 173.70.27 (M5. The study revealed that the gradual increase in ascorbic acid content from green to red and subsequently declined in the lateral stages (red partially dried and red fully dried fruits. The variability of ascorbic acid content in the genotypes suggests that these selected genotypes may be use full as parents in hybridization programs to produce fruits with good nutritional values.

  14. Aortic wall damage in mice unable to synthesize ascorbic acid.

    Science.gov (United States)

    Maeda, N; Hagihara, H; Nakata, Y; Hiller, S; Wilder, J; Reddick, R

    2000-01-18

    By inactivating the gene for L-gulono-gamma-lactone oxidase, a key enzyme in ascorbic acid synthesis, we have generated mice that, like humans, depend on dietary vitamin C. Regular chow, containing about 110 mg/kg of vitamin C, is unable to support the growth of the mutant mice, which require L-ascorbic acid supplemented in their drinking water (330 mg/liter). Upon withdrawal of supplementation, plasma and tissue ascorbic acid levels decreased to 10-15% of normal within 2 weeks, and after 5 weeks the mutants became anemic, began to lose weight, and die. Plasma total antioxidative capacities were approximately 37% normal in homozygotes after feeding the unsupplemented diet for 3-5 weeks. As plasma ascorbic acid decreased, small, but significant, increases in total cholesterol and decreases in high density lipoprotein cholesterol were observed. The most striking effects of the marginal dietary vitamin C were alterations in the wall of aorta, evidenced by the disruption of elastic laminae, smooth muscle cell proliferation, and focal endothelial desquamation of the luminal surface. Thus, marginal vitamin C deficiency affects the vascular integrity of mice unable to synthesize ascorbic acid, with potentially profound effects on the pathogenesis of vascular diseases. Breeding the vitamin C-dependent mice with mice carrying defined genetic mutations will provide numerous opportunities for systematic studies of the role of antioxidants in health and disease.

  15. Effect of ascorbic acid on prevention of hypercholesterolemia induced atherosclerosis.

    Science.gov (United States)

    Das, S; Ray, R; Snehlata; Das, N; Srivastava, L M

    2006-04-01

    The notion that oxidation of lipids and propagation of free radicals may contribute to the pathogenesis of atherosclerosis is supported by a large body of evidence. To circumvent the damage caused by oxygen free radicals, antioxidants are needed which provide the much needed neutralization of free radical by allowing the pairing of electrons. In this study we have investigated the effect of ascorbic acid, a water soluble antioxidant on the development of hypercholesterolemia induced atherosclerosis in rabbits. Rabbits were made hypercholesterolemic and atherosclerotic by feeding 100 mg cholesterol/day. Different doses of ascorbic acid were administered to these rabbits. Low dose of ascorbic acid (0.5 mg/100 g body weight/day) did not have any significant effect on the percent of total area covered by atherosclerotic plaque. However, ascorbic acid when fed at a higher dose (15 mg/100 g body weight/day) was highly effective in reducing the atherogenecity. With this dose the percent of total surface area covered by atherosclerotic plaque was significantly less (p ascorbic acid may have great promise in the prevention of hypercholesterolemia induced atherosclerosis.

  16. Effect of exogenous phytohormones and sucrose on ...

    African Journals Online (AJOL)

    The effect of exogenous phytohormones and sucrose on micropropagation and microtuberization from nodal cuttings of Manihot esculenta was studied. Direct and indirect organogeneses were established from these explants. When nodal cuttings were cultured in the presence of 0.01 to 0.1 mg.L-1 of BAP or NAA there was ...

  17. Exogenous fibrolytic enzymes to unlock nutrients: Histological ...

    African Journals Online (AJOL)

    There is a need for a better understanding of the mode-of-action of exogenous fibrolytic enzymes (EFE) used as additives in ruminant feeds. Four forages, treated with EFE, were evaluated in vitro and histologically, in an attempt to determine the effect of EFE on tissue degradation. Weeping love grass, kikuyu leaf material, ...

  18. Open Syllable Once Again. Endogenous or Exogenous?

    Directory of Open Access Journals (Sweden)

    Raffaele Caldarelli

    2013-02-01

    Full Text Available After a brief reply to some critical remarks raised by Mario Enrietti in a paper published in “Studi Slavistici”, VI (2009, the Author tries to explain why Enrietti’s theory of an exogenous, namely Romance origin of the Slavic open syllable structure should be rejected.

  19. Assessing of distribution, mobility and bioavailability of exogenous Pb in agricultural soils using isotopic labeling method coupled with BCR approach.

    Science.gov (United States)

    Huang, Zhi-Yong; Xie, Hong; Cao, Ying-Lan; Cai, Chao; Zhang, Zhi

    2014-02-15

    The contamination of Pb in agricultural soils is one of the most important ecological problems, which potentially results in serious health risk on human health through food chain. Hence, the fate of exogenous Pb contaminated in agricultural soils is needed to be deeply explored. By spiking soils with the stable enriched isotopes of (206)Pb, the contamination of exogenous Pb(2+) ions in three agricultural soils sampled from the estuary areas of Jiulong River, China was simulated in the present study, and the distribution, mobility and bioavailability of exogenous Pb in the soils were investigated using the isotopic labeling method coupled with a four-stage BCR (European Community Bureau of Reference) sequential extraction procedure. Results showed that about 60-85% of exogenous Pb was found to distribute in reducible fractions, while the exogenous Pb in acid-extractable fractions was less than 1.0%. After planting, the amounts of exogenous Pb presenting in acid-extractable, reducible and oxidizable fractions in rhizospheric soils decreased by 60-66%, in which partial exogenous Pb was assimilated by plants while most of the metal might transfer downward due to daily watering and applying fertilizer. The results show that the isotopic labeling technique coupled with sequential extraction procedures enables us to explore the distribution, mobility and bioavailability of exogenous Pb contaminated in soils, which may be useful for the further soil remediation. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Mitochondria, Energy and Cancer: The Relationship with Ascorbic Acid

    Science.gov (United States)

    González, Michael J.; Rosario-Pérez, Glorivee; Guzmán, Angélica M.; Miranda-Massari, Jorge R.; Duconge, Jorge; Lavergne, Julio; Fernandez, Nadia; Ortiz, Norma; Quintero, Ana; Mikirova, Nina; Riordan, Neil H.; Ricart, Carlos M.

    2012-01-01

    Ascorbic Acid (AA) has been used in the prevention and treatment of cancer with reported effectiveness. Mitochondria may be one of the principal targets of ascorbate's cellular activity and it may play an important role in the development and progression of cancer. Mitochondria, besides generating adenosine triphosphate (ATP), has a role in apoptosis regulation and in the production of regulatory oxidative species that may be relevant in gene expression. At higher concentrations AA may increase ATP production by increasing mitochondrial electron flux, also may induce apoptotic cell death in tumor cell lines, probably via its pro-oxidant action In contrast, at lower concentrations AA displays antioxidant properties that may prevent the activation of oxidant-induced apoptosis. These concentration dependent activities of ascorbate may explain in part the seemingly contradictory results that have been reported previously. PMID:23565030

  1. Ascorbate and dehydroascorbic acid as reliable biomarkers of oxidative stress

    DEFF Research Database (Denmark)

    Lykkesfeldt, Jens

    2007-01-01

    , the analytical reproducibility was tested by repeated analysis of plasma aliquots from one individual over four years. The plasma was subjected to acidic deproteinization with an equal volume of 10% meta-phosphoric acid containing 2 mM EDTA and analyzed for ascorbate and dehydroascorbic acid by high-performance...... liquid chromatography with coulometric detection. In a parallel experiment, stability of human plasma samples treated as above and stored at -80°C for five years was tested in a cohort of 131 individuals. No degradation or shift in the equilibrium between ascorbate and dehydroascorbic acid was observed......Lack of post-sampling stability of ascorbate and dehydroascorbic acid and failure to block their in vivo equilibrium have lowered their value as biomarkers of oxidative stress and limited the ability to further investigate their possible role in disease prevention. In the present paper...

  2. Combined therapy of Ulmo honey (Eucryphia cordifolia and ascorbic acid to treat venous ulcers

    Directory of Open Access Journals (Sweden)

    Mariano del Sol Calderon

    2015-04-01

    Full Text Available OBJECTIVE: to assess the clinical effect of topical treatment using Ulmo honey associated with oral ascorbic acid in patients with venous ulcers. METHOD: longitudinal and descriptive quantitative study. During one year, 18 patients were assessed who were clinically diagnosed with venous ulcer in different stages, male and female, adult, with a mean injury time of 13 months. Ulmo honey was topically applied daily. The dressing was applied in accordance with the technical standard for advanced dressings, combined with the daily oral consumptions of 500 mg of ascorbic acid. The monitoring instrument is the assessment table of venous ulcers. RESULTS: full healing was achieved in 100% of the venous ulcers. No signs of complications were observed, such as allergies or infection. CONCLUSION: the proposed treatment showed excellent clinical results for the healing of venous ulcers. The honey demonstrated debriding and non-adherent properties, was easy to apply and remove and was well accepted by the users. The described results generated a research line on chronic wound treatment.

  3. Determination of Ascorbic Acid Content of Some Fruit Juices and Wine by Voltammetry Performed at Pt and Carbon Paste Electrodes

    Directory of Open Access Journals (Sweden)

    Aurel Pisoschi

    2011-02-01

    Full Text Available A method was developed for assessing ascorbic acid concentration in fruit juices and wine by differential pulse voltammetry. The oxidation peak for ascorbic acid occurs at about 530 mV (versus SCE on a Pt strip working electrode and at about 470 mV on a carbon paste working electrode. The influence of the operational parameters like the pulse amplitude and the pulse period on the analytical signal was investigated. The obtained calibration graph shows a linear dependence between the peak height and ascorbic acid concentration within the range 0.31-20 mM with a Pt working electrode, and within the range 0.07-20 mM with a carbon paste working electrode. The equation of the calibration graph was y = 21.839x + 35.726, r2 = 0.9940, when a Pt strip electrode was used (where y represents the value of the current intensity measured for the peak height, expressed as µA and x the analyte concentration, as mM. R.S.D. = 2.09%, n = 10, Cascorbic acid = 2.5 mM. The equation of the calibration graph was y = 3.4429x + 5.7334, r2 = 0.9971, when a carbon paste electrode was used (where y represents the value of intensity measured for the peak height, expressed as µA and x the analyte concentration, as mM. R.S.D. = 2.35%, n = 10, Cascorbic acid = 2.5 mM. The developed method was applied to ascorbic acid assessment in fruit juices and wine. The ascorbic acid content determined ranged between 6.83 mg/100 mL juice for soft drinks (Fanta Madness and 54.74 mg/100 mL for citrus (lemon juices obtained by squeezing fruit. Different ascorbic acid concentrations (from standard solutions were added to the analysed samples, the degree of recovery being comprised between 94.74 and 104.97%. The results of ascorbic acid assessment by differential pulse voltammetry were compared with those obtained by cyclic voltammetry. The results obtained by the two methods were in good agreement.

  4. A sensor of a polyoxometalate and Au–Pd alloy for simultaneously detection of dopamine and ascorbic acid

    International Nuclear Information System (INIS)

    Zhou, Chunlei; Li, Shuang; Zhu, Wei; Pang, Haijun; Ma, Huiyuan

    2013-01-01

    A composite film based on K 8 P 2 W 16 V 2 O 62 ·18H 2 O decorated by Au–Pd nanoparticles was prepared by the layer-by-layer self-assembly method. This composite film exhibits enhanced electrocatalytic performance, repeatability and long-term stability for the simultaneous determination of dopamine and ascorbic acid at biological pH (pH 7.0). The proposed electrochemical sensing film for simultaneous detecting dopamine and ascorbic acid shows rather low detection limit of 8.3 × 10 −7 and 4.3 × 10 −7 M and a linear response range from 2.1 × 10 −6 to 2.06 × 10 −3 M and 1.2 × 10 −6 to 1.61 × 10 −3 M, as well as no interference from the common interfering species at an applied potential. -- Abstract: A novel composite film based on Dawson-type phosphovanadotungstate K 8 P 2 W 16 V 2 O 62 ·18H 2 O (P 2 W 16 V 2 ) decorated by Au–Pd alloy nanoparticles (Au–Pd) was fabricated on quartz, silicon and ITO using the layer-by-layer self-assembly method. The composite film was characterized by UV–vis spectroscopy, X-ray photoelectron spectra, atomic force microscopy, Scanning electronic microscope, cyclic voltammetry and differential pulse voltammetry. The composite film can be employed for sensitive and simultaneous determination of dopamine and ascorbic acid at biological pH (pH 7.0). Linear analytical curves were obtained in the ranges from 2.1 × 10 −6 to 2.06 × 10 −3 M and 1.2 × 10 −6 to 1.61 × 10 −3 M for dopamine and ascorbic acid by DPV methods, respectively. The low detection limit for dopamine and ascorbic acid were 8.3 × 10 −7 and 4.3 × 10 −7 M, as well as no interference was observed from the common interfering species such as glucose, uric acid, L-cysteine, CH 3 OH, CH 3 CH 2 OH and H 2 O 2 . The composite film was used for dopamine and ascorbic acid determinations in real samples with satisfactory results. With high sensitivity and selectivity, the proposed electrochemical sensor would provide a simple method for

  5. All-solid-state potentiometric sensors for ascorbic acid by using a screen-printed compatible solid contact

    International Nuclear Information System (INIS)

    Veltsistas, Panayotis G.; Prodromidis, Mamas I.; Efstathiou, Constantinos

    2004-01-01

    The development of all-solid-state potentiometric ion selective electrodes for monitoring of ascorbic acid, by using a screen-printed compatible solid contact is described. The applied methodology is based on the use of PVC membrane modified with some firstly-tested ionophores (triphenyltin(IV)chloride, triphenyltin(IV)hydroxide and palmitoyl-L-ascorbic acid) and a novel one synthesized in our laboratory (dibutyltin(IV) diascorbate). Synthesis protocol and some preliminary identification studies are given. A conductive graphite-based polymer thick film ink was used as an internal solid contact between the graphite electrode and the PVC membrane. The presence and the nature of the solid contact (plain or doped with lanthanum 2,6-dichlorophenolindophenol (DCPI)) seem to enhance the analytical performance of the electrodes in terms of sensitivity, dynamic range, and response time. The analytical performance of the constructed electrodes was evaluated with potentiometry, constant-current chronopotentiometry and electrochemical impedance spectroscopy (EIS). The interference effect of various compounds was also tested. The potential response of the optimized Ph 3 SnCl-based electrode was linear against ascorbic acid concentration range 0.005-5.0 mM. The applicability of the proposed sensors in real samples was also tested. The detection limit was 0.002 mM ascorbic acid (50 mM phosphate, pH 5 in 50 mM KCl). The slope of the electrodes was super-Nernstian and pH dependent, indicating a mechanism involving a combination of charge transfer and ion exchange processes. Fabrication of screen-printed ascorbate ISEs has also been demonstrated

  6. Antimicrobial activity optimization of nisin, ascorbic acid and ethylenediamine tetraacetic acid disodium salt (EDTA against Salmonella Enteritidis ATCC 13076 using response surface methodology

    Directory of Open Access Journals (Sweden)

    Nongpanga Sangcharoen

    2017-10-01

    Full Text Available Nisin is a commercial bacteriocin produced by Lactococcus lactis subsp. lactis and widely used as a natural preservative in the food industry. However, while nisin alone cannot inhibit the growth of Gram-negative bacteria, it can in combination with a chelating agent or organic acid. This study combined nisin with some chelating agents, weak organic acids and their salts to inhibit Salmonella Enteritidis ATCC 13076. The combinations of nisin (2000 parts per million; ppm and ascorbic acid (2000 ppm or ethylenediamine tetraacetic acid disodium salt (EDTA; 7400 ppm showed significant inhibitory effects on the target strain. Due to regulatory limits, the second part of the study reduced the concentrations of nisin, ascorbic acid and EDTA to 500 ppm, 2000 ppm and 250 ppm, respectively. The mixture of nisin, ascorbic acid and EDTA showed the highest inhibitory effect with a reduction number of 3.41 log colony forming units (p < 0.05. To minimize the growth of S. Enteritidis ATCC 13076, central composite design and response surface methodology were applied to investigate the combined effect of nisin (0–500 ppm, ascorbic acid (0–2000 ppm, and EDTA (0–250 ppm on the target strain growth. Among the three factors, nisin had a higher antimicrobial effect than ascorbic acid or EDTA, while an increase in nisin resulted in a decrease in S. Enteritidis ATCC 13076 growth. The optimum concentration was 500 ppm nisin with 1515 ppm ascorbic acid and 250 ppm EDTA. Under these conditions, the growth of S. Enteritidis ATCC 13076 predicted by the model was 24.99%. Keywords: Antimicrobial activity, Ascorbic acid, Ethylenediamine tetraacetic acid disodium salt (EDTA, Nisin, Salmonella enteritidis

  7. Response of antioxidant system of tomato to water deficit stress and its interaction with ascorbic acid

    Directory of Open Access Journals (Sweden)

    Fatemeh Daneshmand

    2014-03-01

    Full Text Available Environmental stresses including water deficit stress may produce oxidants such as reactive oxygen species that damage the membrane structure in plants. Among the antioxidants, ascorbic acid has a critical role in the cell and scavenges reactive oxygen species. In this research, effects of ascorbic acid at two levels (0 and 10 mM and water deficit stress based on 3 levels of field capacity (100, 60 and 30% were studied in tomato plants. Both levels of stress increased lipid peroxidation, reduced the amount of ascorbic acid and glutathione and increased the activity of enzymes superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, guaiacol peroxidase and reduced the growth parameters. Ascorbic acid treatment, reduced lipid peroxidation, increased ascorbic acid and glutathione levels and decreased the activity of superoxide dismutase, catalase, ascorbate peroxidase, glutathione peroxidase and guaiacol peroxidase and positive effects of ascorbic acid treatment appeared to improve the plant growth parameters.

  8. Ascorbate concentrations in vitro and in vivo, and their role in the radiation response of cells

    International Nuclear Information System (INIS)

    Stratford, M.R.L.; Hodgkiss, R.J.

    1985-01-01

    Hydrogen-atom or electron-transfer reactions of ascorbate are often invoked in discussing its potential role in radiobiology and free radical damage by cytotoxins, but detailed information on actual levels in experimental systems is lacking. A range of 0-250 μM ascorbate is present in several commonly used mammalian cell culture media. V79 379A Chinese hamster cells can concentrate ascorbate from medium containing 200 or 500 μM ascorbate but when ascorbate is absent in medium, cells do not appear to contain a significant amount. Tumour concentrations are approximately 1mM, similar to that of glutathione (GSH). There is much current interest in depleting cells of GSH to enhance radiosensitivity, and ascorbate is maintained by a GSH dependent enzyme, glutathione dehydrogenase. Data is presented on the effect of GSH depletion by buthionine sulphoximine on cell and tumour ascorbate levels, and the effect of ascorbate on in vitro radiosensitivity, and misonidazole sensitizing efficiency

  9. Exogenous and endogenous landforms in the Mediterranean

    Science.gov (United States)

    Acar, Julia

    2017-04-01

    11th graders have already learned about endogenous forces and now we are having a closer look at the exogenous forces which act on the Earth's surface. The Po River-system, for example, is responsible for the formation of the alpine region. Students are asked to find out how this works with the help of the rock-cycle scheme, several suitable maps and information on weathering and the texture of rocks, erosion, etc. We will form groups that will look at different types of rock formations (including an example in the Mediterranean region each). Depending on the number of lessons available we will add the exogenous effect of flowing water and ice (glacial over forming) to the topic. At the end every group will present their findings explaining the scientific context by using topographic examples.

  10. Exogenous shocks and governing energy security

    OpenAIRE

    Diriöz, Ali Oğuz

    2017-01-01

    Cataloged from PDF version of article. Thesis (Ph.D.): Bilkent University, Department of International Relations, İhsan Doğramacı Bilkent University, 2017. Includes bibliographical references (leaves 219-248). The research examines how governments maintain energy security when faced with exogenous shocks. The main focus of inquiry examines the relative influence of markets vs. geopolitics in the area of energy security using the comparative case studies of Turkey, France, and Netherl...

  11. Exogenous sample contamination. Sources and interference.

    Science.gov (United States)

    Cornes, Michael P

    2016-12-01

    Clinical laboratory medicine is involved in the vast majority of patient care pathways. It has been estimated that pathology results inform 60-70% of critical patient care decisions. The primary goal of the laboratory is to produce precise and accurate results which reflect the true situation in vivo. It is not surprising that interference occurs in laboratory analysis given the complexity of some of the assays used to perform them. Interference is defined as "the effect of a substance upon any step in the determination of the concentration or catalytic activity of the metabolite". Exogenous interferences are defined as those that derive from outside of the body and are therefore not normally found in a specimen and can cause either a positive or negative bias in analytical results. Interferences in analysis can come from various sources and can be classified as endogenous or exogenous. Exogenous substances could be introduced at any point in the sample journey. The laboratory must take responsibility for the quality of results produced. It has a responsibility to have processes in place to identify and minimise the occurrence and effect contamination and interference. To do this well the laboratory needs to work with clinicians and manufacturers. Failure to identify an erroneous result could have an impact on patient care, patient safety and also on hospital budgets. However it is not always easy to recognise interferences. This review summarises the types and sources of exogenous interference and some steps to minimise the impact they have. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  12. The cellular receptors of exogenous RNA

    Directory of Open Access Journals (Sweden)

    Patryk Reniewicz

    2016-04-01

    Full Text Available One of the key determinants of survival for organisms is proper recognition of exogenous and endogenous nucleic acids. Therefore, high eukaryotes developed a number of receptors that allow for discrimination between friend or foe DNA and RNA. Appearance of exogenous RNA in cytoplasm provides a signal of danger and triggers cellular responses that facilitate eradication of a pathogen. Recognition of exogenous RNA is additionally complicated by fact that large amount of endogenous RNA is present in cytoplasm Thus, number of different receptors, found in eukaryotic cells, is able to recognize that nucleic acid. First group of those receptors consist endosomal Toll like receptors, namely TLR3, TLR7, TLR8 and TLR13. Those receptors recognize RNA released from pathogens that enter the cell by endocytosis. The second group includes cytoplasmic sensors like PKR and the family of RLRs comprised of RIG-I, MDA5 and LGP2. Cytoplasmic receptors recognize RNA from pathogens invading the cell by non-endocytic pathway. In both cases binding of RNA by its receptors results in activation of the signalling cascades that lead to the production of interferon and other cytokines.

  13. Transport of ascorbic acid and dehydroascorbic acid by pancreatic islet cells from neonatal rats

    DEFF Research Database (Denmark)

    Zhou, A; Farver, O; Thorn, N A

    1991-01-01

    . Dehydroascorbic acid was converted to ascorbic acid by an unknown mechanism after uptake. The uptake of both ascorbic acid and dehydroascorbic acid was inhibited by tri-iodothyronine, and uptake of ascorbic acid, but not of dehydroascorbic acid, was inhibited by glucocorticoids. Isolated secretory granules...

  14. Influence of enzymes and ascorbic acid on dough rheology and ...

    African Journals Online (AJOL)

    The combined action of ascorbic acid and two commercial enzymatic complexes containing amylase and xylanase/amylase was analyzed to determine their effects on dough rheology and bread quality. Seven bread formulations containing different concentrations of these improvers were used in the analysis.

  15. Vitamin C (ascorbic acid) requirements of Heterobranchus longifilis ...

    African Journals Online (AJOL)

    SERVER

    2007-07-04

    Jul 4, 2007 ... Fish fed the control (0 mg vitamin C kg-1) diet exhibited deficiency signs including lordosis, caudal fin deformity, ... INTRODUCTION. Vitamin C (ascorbic acid) belongs to the water-soluble group of vitamin. Its importance in fish diets and characteristics had been described by various authors. (Lim and Lovell ...

  16. ANTIOXIDANT AND PRO-OXIDANT EFFECT OF ASCORBIC ACID

    Directory of Open Access Journals (Sweden)

    Goran Rankovic

    2005-01-01

    Full Text Available Free radicals attack proteins, lipids, enzymes and DNA causing pathological changes in organism. There are many mechanisms that organism uses to fight against free radicals. Ascorbic acid is one of the strongest reducers and eliminators of free radicals. It reduces stable oxygenic, azoth and thyol radicals and acts as a primary defense against water radicals in blood. When radicals are dissolved in water suspensions of erythrocytes and low density lipoproteins (LDL, ascorbic acid catches and eliminates free radicals before they arrive to the membrane and LDL molecules. Even though ascorbic acid is not capable of eliminating free radicals out of fluid medium, it acts as synergist to alpha-tocopherol in lipid section, contributes to the lessening of lipid tocoperoxil radicals, and above all, regenerates alpha-tocopherol. Ascorbic acid may act as pro-oxidant under in vitro conditions in the presence of metals; however, this effect is probably not important under in vivo conditions where metal ions, being sequestered, become second reducers.

  17. Ascorbic acid, β-carotene, total phenolic compound and ...

    African Journals Online (AJOL)

    A two year study at Alexandria University compared ascorbic acid, β-carotene, total phenolic compound, nitrite content and microbiological quality of orange and strawberry fruits grown under organic and conventional management techniques to see if producers concerns are valid. Organically grown oranges and ...

  18. Mixed metal complexes of isoniazid and ascorbic acid: chelation ...

    African Journals Online (AJOL)

    Novel mixed complexes of isoniazid and ascorbic acid have been synthesized and characterized using infrared, electronic absorption data, elemental analysis, molar conductivity, melting point, thin layer chromatography and solubility. The metal ions involved in the complex formation are Cu2+, Zn2+ and Cd2+. The melting ...

  19. Influence of enzymes and ascorbic acid on dough rheology and ...

    African Journals Online (AJOL)

    Influence of enzymes and ascorbic acid on dough rheology and wheat bread quality. ... Journal Home > Vol 15, No 3 (2016) >. Log in or ... Seven bread formulations containing different concentrations of these ... The rheological properties of each dough formulation were determined by moisture, gluten and farinograph tests.

  20. ASCORBIC ACID IS DECREASED IN INDUCED SPUTUM OF MILD ASTHMATICS

    Science.gov (United States)

    Asthma is primarily an airways inflammatory disease, and the bronchial airways have been shown to be particularly susceptible to oxidant-induced tissue damage. The antioxidant ascorbic acid (AA) plays an essential role in defending against oxidant attack in the airways. Decreased...

  1. Determination of ascorbic acid content of some tropical fruits by ...

    African Journals Online (AJOL)

    The ascorbic acid content of three common juicy tropical fruits, orange, water melon and cashew, were determined using iodometric titration method under three temperature regimes (refrigerated, room temperature, and heated to about 80 oC), representing the range of temperatures the fruits may be exposed to during ...

  2. Ameliorative effects of betaine and ascorbic acid administration to ...

    African Journals Online (AJOL)

    This review highlights the huge challenges heat stress pose to profitable production of broiler chickens during the hot-dry season. It also enumerates the negative effects of heat stress due to excess production of reactive oxygen species (ROS) in broiler chickens. It emphasizes that administration of betaine and/or ascorbic ...

  3. Effect of ascorbic and folic acids supplementation on oxidative ...

    African Journals Online (AJOL)

    An experiment was conducted on the effect of supplementation of ascorbic and folic acids on the oxidative hormones, enzymatic antioxidants, haematological and biochemical properties of layers exposed to increased heat load. A total of 72 Isa Brown laying hens at 31 weeks of age were randomly divided into four groups ...

  4. Chemical dosimetry by UV spectrophotometry of aqueous ascorbic acid solutions

    International Nuclear Information System (INIS)

    Alian, A.; El-Assay, N.B.; Abdel-Rehim, F.; Amin, N.E.; McLaughlin, W.L.; Roushdy, H.

    1984-01-01

    The decrease in the ultraviolet absorption of aqueous solutions of ascorbic acid brought about by large doses of gamma radiation has been investigated as a means of developing a new chemical dosimeter. Because of spontaneous ring opening under various conditions after dissolution in water, some additives were examined as possible stabilizers against such denaturing of aqueous ascorbic acid. At an ascorbic acid concentration of 10 -4 M, either 1 to 2% glycine or 0.2 M NaCl was found to be a good stabilizer. A mechanism of radiation chemistry has been proposed based on hydroxyl radical and hydroxyl adduct intermediates, leading to dehydroascorbic acid through the ascorbate complex. The optimum dosimeter solution covers an absorbed dose range approx. 50 to 350 Gy, when measured at 264 nm wavelength. The G-values for dehydroascorbic acid production were determined to be 2.94 +- 0.33 and 2.43 +- 0.11 (100 eV) -1 , with glycine and NaCl used respectively as stabilizers. (author)

  5. Ascorbic acid for the healing of skin wounds in rats

    Directory of Open Access Journals (Sweden)

    CC. Lima

    Full Text Available BACKGROUND: Healing is a complex process that involves cellular and biochemical events. Several medicines have been used in order to shorten healing time and avoid aesthetic damage. OBJECTIVE: to verify the topical effect of ascorbic acid for the healing of rats' skin wounds through the number of macrophages, new vessels and fibroblast verifications in the experimental period; and analyse the thickness and the collagen fibre organization in the injured tissue. METHODS: Male Rattus norvegicus weighing 270 ± 30 g were used. After thionembutal anesthesia, 15 mm transversal incisions were made in the animals' cervical backs. They were divided into two groups: Control Group (CG, n = 12 - skin wound cleaned with water and soap daily; Treated Group (TG, n = 12 - skin wound cleaned daily and treated with ascorbic acid cream (10%. Samples of skin were collected on the 3rd, 7th and 14th days. The sections were stained with hematoxylin-eosin and picrosirius red for morphologic analysis. The images were obtained and analysed by a Digital Analyser System. RESULTS: The ascorbic acid acted on every stage of the healing process. It reduced the number of macrophages, increased the proliferation of fibroblasts and new vessels, and stimulated the synthesis of thicker and more organized collagen fibres in the wounds when compared to CG. CONCLUSION: Ascorbic acid was shown to have anti-inflammatory and healing effects, guaranteeing a suiTable environment and conditions for faster skin repair.

  6. Plasma Ascorbic Acid and Non-Enzymatic Antioxidants Level in ...

    African Journals Online (AJOL)

    Free radicals have been implicated in the pathology of several diseases including cataract. Ascorbic acid functions as the major chain breaking antioxidant vitamin in the aqueous phase. Bilirubin, albumin and uric acid are regarded as natural antioxidants. There are conflicting reports on plasma concentrations of these ...

  7. 21 CFR 172.315 - Nicotinamide-ascorbic acid complex.

    Science.gov (United States)

    2010-04-01

    ... 172.315 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.315 Nicotinamide-ascorbic acid complex...

  8. Silver nanoparticles prepared in presence of ascorbic acid and ...

    Indian Academy of Sciences (India)

    Administrator

    (AgNPs) by using ascorbic acid as reducing agent and gelatin as stabilizer. ... variety of organic and inorganic reactions (Hernández-. Santos et al ... The morphology and size of the nanoparticles can be con- ... the overpotentials of many analytes that occur at unmodi- ... implemented by a copper wire lead fitted into a glass.

  9. Plasma Concentration of Ascorbic Acid and Some Hematological ...

    African Journals Online (AJOL)

    Background: Tobacco snuffing, like cigarette smoking, is known to be a common habit among the adults of Igbo communities in Nigeria. In view of the various pharmacological actions of nicotine and other additive constituents of tobacco snuff, there is growing concern that ascorbic acid, which is a vital antioxidant, and blood ...

  10. Effects of calcium gluconate and ascorbic acid on controlling shoot ...

    African Journals Online (AJOL)

    In vitro shoot necrosis is a quite widespread disorder affecting raspberry micropropagation. This study was conducted to investigate effects of calcium gluconate and ascorbic acid on shoot necrosis and dieback of raspberry shoots during micropropagation. Nodal segments of primocane-fruiting raspberry cultivars 'Allgold', ...

  11. Formulation and Evaluation of Ascorbic acid Tablets by Direct ...

    African Journals Online (AJOL)

    PURPOSE: To evaluate the tableting properties of microcrystalline starch (MCS) used as a direct compression excipient in the formulation of ascorbic acid tablets and to compare with the properties of tablets produced using microcrystalline cellulose (MCC). METHODS: MCS was obtained by partial hydrolysis of cassava ( ...

  12. Formulation and Evaluation of Ascorbic acid Tablets by Direct ...

    African Journals Online (AJOL)

    Formulation and Evaluation of Ascorbic acid Tablets by Direct Compression using Microcrystalline Starch as a Direct Compression Excipient. ... Abstract. PURPOSE: To evaluate the tableting properties of microcrystalline starch (MCS) used as a direct ... RESULTS: Mechanical properties of tablets formulated with MCS were

  13. Chromium-induced membrane damage: protective role of ascorbic acid.

    Science.gov (United States)

    Dey, S K; Nayak, P; Roy, S

    2001-07-01

    Importance of chromium as environmental toxicant is largely due to impact on the body to produce cellular toxicity. The impact of chromium and their supplementation with ascorbic acid was studied on plasma membrane of liver and kidney in male Wistar rats (80-100 g body weight). It has been observed that the intoxication with chromium (i.p.) at the dose of 0.8 mg/100 g body weight per day for a period of 28 days causes significant increase in the level of cholesterol and decrease in the level of phospholipid of both liver and kidney. The alkaline phosphatase, total ATPase and Na(+)-K(+)-ATPase activities were significantly decreased in both liver and kidney after chromium treatment, except total ATPase activity of kidney. It is suggested that chromium exposure at the present dose and duration induce for the alterations of structure and function of both liver and kidney plasma membrane. Ascorbic acid (i.p. at the dose of 0.5 mg/100 g body weight per day for period of 28 days) supplementation can reduce these structural changes in the plasma membrane of liver and kidney. But the functional changes can not be completely replenished by the ascorbic acid supplementation in response to chromium exposure. So it is also suggested that ascorbic acid (nutritional antioxidant) is useful free radical scavenger to restrain the chromium-induced membrane damage.

  14. Ameliorative effect of ascorbic acid on mercury chloride‑induced ...

    African Journals Online (AJOL)

    Introduction: Mercury is a highly toxic metal that exerts its adverse effects on the health of humans and animals through air, soil, water and food. Aim: The present study was aimed at the evaluation of the effects of ascorbic acid on mercury chloride-induced changes on the histomorphology of the spleen of adult Wistar Rats.

  15. The biochemical, physiological and therapeutic roles of ascorbic acid

    African Journals Online (AJOL)

    Ascorbic acid is an important micronutrient necessary for a significant number of metabolic reactions in humans and other primates. It is a strong reducing agent involved in reduction reaction and it is structurally related to glucose. Experimental and epidemiological studies have documented the biochemical, physiological ...

  16. Thylakoid-bound ascorbate peroxidase increases resistance to salt ...

    African Journals Online (AJOL)

    Reactive oxygen species (ROS) are cellular indicators of stress. In plants, they function as secondary messengers in response to environmental stress. Ascorbate peroxidase (APX) is an important enzyme directly involved in the scavenging of ROS. In this study, we aimed at identifying the function of the Brassica napus ...

  17. Partial Granger causality--eliminating exogenous inputs and latent variables.

    Science.gov (United States)

    Guo, Shuixia; Seth, Anil K; Kendrick, Keith M; Zhou, Cong; Feng, Jianfeng

    2008-07-15

    Attempts to identify causal interactions in multivariable biological time series (e.g., gene data, protein data, physiological data) can be undermined by the confounding influence of environmental (exogenous) inputs. Compounding this problem, we are commonly only able to record a subset of all related variables in a system. These recorded variables are likely to be influenced by unrecorded (latent) variables. To address this problem, we introduce a novel variant of a widely used statistical measure of causality--Granger causality--that is inspired by the definition of partial correlation. Our 'partial Granger causality' measure is extensively tested with toy models, both linear and nonlinear, and is applied to experimental data: in vivo multielectrode array (MEA) local field potentials (LFPs) recorded from the inferotemporal cortex of sheep. Our results demonstrate that partial Granger causality can reveal the underlying interactions among elements in a network in the presence of exogenous inputs and latent variables in many cases where the existing conditional Granger causality fails.

  18. A panel Granger-causality test of endogenous vs. exogenous growth

    OpenAIRE

    Jochen Hartwig

    2009-01-01

    The paper proposes a new test of endogenous vs. exogenous growth theories based on the Granger-causality methodology and applies it to a panel of 20 OECD countries. The test yields divergent evidence with respect to physical and human capital. For physical capital, the test results favor Solow-type exogenous growth theory over AK-type endogenous growth models. On the other hand, the test results lend support to human capital oriented endogenous growth models - like the Uzawa-Lucas model - rat...

  19. Localization of ascorbic acid, ascorbic acid oxidase, and glutathione in roots of Cucurbita maxima L.

    Science.gov (United States)

    Liso, Rosalia; De Tullio, Mario C; Ciraci, Samantha; Balestrini, Raffaella; La Rocca, Nicoletta; Bruno, Leonardo; Chiappetta, Adriana; Bitonti, Maria Beatrice; Bonfante, Paola; Arrigoni, Oreste

    2004-12-01

    To understand the function of ascorbic acid (ASC) in root development, the distribution of ASC, ASC oxidase, and glutathione (GSH) were investigated in cells and tissues of the root apex of Cucubita maxima. ASC was regularly distributed in the cytosol of almost all root cells, with the exception of quiescent centre (QC) cells. ASC also occurred at the surface of the nuclear membrane and correspondingly in the nucleoli. No ASC could be observed in vacuoles. ASC oxidase was detected by immunolocalization mainly in cell walls and vacuoles. This enzyme was particularly abundant in the QC and in differentiating vascular tissues and was absent in lateral root primordia. Administration of the ASC precursor L-galactono-gamma-lactone markedly increased ASC content in all root cells, including the QC. Root treatment with the ASC oxidized product, dehydroascorbic acid (DHA), also increased ASC content, but caused ASC accumulation only in peripheral tissues, where DHA was apparently reduced at the expense of GSH. The different pattern of distribution of ASC in different tissues and cell compartments reflects its possible role in cell metabolism and root morphogenesis.

  20. Polymorphisms in sodium-dependent vitamin C transporter genes and plasma, aqueous humor and lens nucleus ascorbate concentrations in an ascorbate depleted setting.

    Science.gov (United States)

    Senthilkumari, Srinivasan; Talwar, Badri; Dharmalingam, Kuppamuthu; Ravindran, Ravilla D; Jayanthi, Ramamurthy; Sundaresan, Periasamy; Saravanan, Charu; Young, Ian S; Dangour, Alan D; Fletcher, Astrid E

    2014-07-01

    We have previously reported low concentrations of plasma ascorbate and low dietary vitamin C intake in the older Indian population and a strong inverse association of these with cataract. Little is known about ascorbate levels in aqueous humor and lens in populations habitually depleted of ascorbate and no studies in any setting have investigated whether genetic polymorphisms influence ascorbate levels in ocular tissues. Our objectives were to investigate relationships between ascorbate concentrations in plasma, aqueous humor and lens and whether these relationships are influenced by Single Nucleotide Polymorphisms (SNPs) in sodium-dependent vitamin C transporter genes (SLC23A1 and SLC23A2). We enrolled sixty patients (equal numbers of men and women, mean age 63 years) undergoing small incision cataract surgery in southern India. We measured ascorbate concentrations in plasma, aqueous humor and lens nucleus using high performance liquid chromatography. SLC23A1 SNPs (rs4257763, rs6596473) and SLC23A2 SNPs (rs1279683 and rs12479919) were genotyped using a TaqMan assay. Patients were interviewed for lifestyle factors which might influence ascorbate. Plasma vitamin C was normalized by a log10 transformation. Statistical analysis used linear regression with the slope of the within-subject associations estimated using beta (β) coefficients. The ascorbate concentrations (μmol/L) were: plasma ascorbate, median and inter-quartile range (IQR), 15.2 (7.8, 34.5), mean (SD) of aqueous humor ascorbate, 1074 (545) and lens nucleus ascorbate, 0.42 (0.16) (μmol/g lens nucleus wet weight). Minimum allele frequencies were: rs1279683 (0.28), rs12479919 (0.30), rs659647 (0.48). Decreasing concentrations of ocular ascorbate from the common to the rare genotype were observed for rs6596473 and rs12479919. The per allele difference in aqueous humor ascorbate for rs6596473 was -217 μmol/L, p humor ascorbate were higher for the GG genotype of rs6596473: GG, β = 1460 compared to

  1. The inter-relationship of ascorbate transport, metabolism and mitochondrial, plastidic respiration.

    Science.gov (United States)

    Szarka, András; Bánhegyi, Gábor; Asard, Han

    2013-09-20

    Ascorbate, this multifaceted small molecular weight carbohydrate derivative, plays important roles in a range of cellular processes in plant cells, from the regulation of cell cycle, through cell expansion and senescence. Beyond these physiological functions, ascorbate has a critical role in responses to abiotic stresses, such as high light, high salinity, or drought. The biosynthesis, recycling, and intracellular transport are important elements of the balancing of ascorbate level to the always-changing conditions and demands. A bidirectional tight relationship was described between ascorbate biosynthesis and the mitochondrial electron transfer chain (mETC), since L-galactono-1,4-lactone dehydrogenase (GLDH), the enzyme catalyzing the ultimate step of ascorbate biosynthesis, uses oxidized cytochrome c as the only electron acceptor and has a role in the assembly of Complex I. A similar bidirectional relationship was revealed between the photosynthetic apparatus and ascorbate biosynthesis since the electron flux through the photosynthetic ETC affects the biosynthesis of ascorbate and the level of ascorbate could affect photosynthesis. The details of this regulatory network of photosynthetic electron transfer, respiratory electron transfer, and ascorbate biosynthesis are still not clear, as are the potential regulatory role and the regulation of intracellular ascorbate transport and fluxes. The elucidation of the role of ascorbate as an important element of the network of photosynthetic, respiratory ETC and tricarboxylic acid cycle will contribute to understanding plant cell responses to different stress conditions.

  2. Interrelationship of dietary lipids and ascorbic acid with hepatic enzymes of cholesterol metabolic pathway.

    Science.gov (United States)

    Sen, S; Mukherjee, S

    1997-01-01

    Effect of unsaturated and saturated fats on cholesterol metabolism was studied in ascorbate sufficient and deficient guineapigs. Experimental animals were made chronic ascorbic acid deficient by allowing oral intake of 0.5 mg ascorbic acid/day/animal. Elevation in serum and liver cholesterol and triglyceride along with depression in cholesterol oxidation and 7 alpha-hydroxylation in liver was observed in unsaturated fat fed guineapigs with ascorbate deficiency. Liver microsomal cytochrome P-450 level was found to be low in ascorbate deficient animals. Polyunsaturated fat intake could not lower the serum cholesterol level in ascorbate deficiency. Today polyunsaturated fat in the diet is encouraged all over the world for its hypocholesterolemic effect. This study indicates that polyunsaturated fat intake with ascorbic acid deficiency may produce hypercholesterolemia.

  3. Ocularity Feature Contrast Attracts Attention Exogenously

    Directory of Open Access Journals (Sweden)

    Li Zhaoping

    2018-02-01

    Full Text Available An eye-of-origin singleton, e.g., a bar shown to the left eye among many other bars shown to the right eye, can capture attention and gaze exogenously or reflexively, even when it appears identical to other visual input items in the scene and when the eye-of-origin feature is irrelevant to the observer’s task. Defining saliency as the strength of exogenous attraction to attention, we say that this eye-of-origin singleton, or its visual location, is salient. Defining the ocularity of a visual input item as the relative difference between its left-eye input and its right-eye input, this paper shows the general case that an ocularity singleton is also salient. For example, a binocular input item among monocular input items is salient, so is a left-eye-dominant input item (e.g., a bar with a higher input contrast to the left eye than to the right eye among right-eye-dominant items. Saliency by unique input ocularity is analogous to saliency by unique input colour (e.g., a red item among green ones, as colour is determined by the relative difference(s between visual inputs to different photoreceptor cones. Just as a smaller colour difference between a colour singleton and background items makes this singleton less salient, so does a smaller ocularity difference between an ocularity singleton and background items. While a salient colour difference is highly visible, a salient ocularity difference is often perceptually invisible in some cases and discouraging gaze shifts towards it in other cases, making its behavioural manifestation not as apparent. Saliency by ocularity contrast provides another support to the idea that the primary visual cortex creates a bottom-up saliency map to guide attention exogenously.

  4. ENDOGENOUS OR EXOGENOUS INNOVATION DEVELOPMENT IN INDUSTRY ON REGIONAL LEVEL?

    Directory of Open Access Journals (Sweden)

    Arkadiusz Świadek

    2014-04-01

    Full Text Available At the moment endogenous growth theory has become increasingly popular in the world of science, particularly in developed countries. This article aims to show, for two regions case, the needs and sense of applying this theory in the polish regions. Due to the low level of economic development of many Polish regions, they are unable to growth in a comparable rate as regions in developed countries. This explains the economic divergence between polish regions and the highly developed regions of Europe and the World. Stimulating economic growth is insufficient in such cases, because of the weakness of its internal factors. Therefore it is important to strengthen an external impact to keep internal development. It means that the endogenous growth theory is no reason to exist, in conditions of poor polish regions. Without external inputs there can’t be convergences processes. Therefore, the economic development of the Polish regions should be based on the exogenous growth theory.

  5. Iodine application increased ascorbic acid content and modified the vascular tissue in opuntia ficus-indica

    International Nuclear Information System (INIS)

    Osuna, H.T.G.; Morales, R.; Rubio, E.M.; Mendoza, A.B.; Ruvalcaba, R.M

    2014-01-01

    The objective of this study was to discern the effect of applying both iodide and iodate to Opuntia ficus indica irrigation. The effect of iodate (KIO/sub 3/, 10-4 M) and iodide (KI, 10-4 M) on plant growth, yield and morphology was studied. Experiments were carried in three samples under tunnel conditions. In the last sampling, iodine species (KIO/sub 3/, KI) caused a negative effect in biomass. The amount of ascorbic acid, however, was increased over 51% in both iodine treatments. Phosphorus (0.26%), iron (50 ppm), and magnesium (1402 ppm) increases were also observed with iodate treatment in the first sampling, and increases in potassium (46.8 ppm) were apparent in the second. Iodide treatment increased the amounts of copper (1.02 ppm) and manganese (32.80 ppm) in the first sampling. Iodate treatment modified the number of xylem vessels and increased both the mucilage area and amount of druses. In general this study shows that iodate increases the amount of ascorbic acid and the morphology of the vascular tissue. (author)

  6. Rapid and specific spectrophotometric and RP-HPLC methods for the determination of ascorbic acid in fruits juices and in human plasma

    International Nuclear Information System (INIS)

    Arayne, M.S.; Bibi, Z.; Sultana, N.

    2009-01-01

    Ascorbic acid (AA) is one of the most important water soluble vitamin in the human diet, present naturally in a wide range of foods, especially fruits and vegetables. The objective of this study was to develop a rapid, sensitive and specific method for the determination of ascorbic acid (vitamin C) from a variety of sources like fresh fruits or from human plasma using spectrophotometric technique or by RP-HPLC. Initially, estimation of vitamin C was carried out spectrophotometrically as UV spectroscopy is a trusted technique to monitor small quantities of drugs and vitamins. The assay was linear over the concentration range of 0.05-100 mi cro g/mL/sup -I/. In the second procedure, we attempted to separate and quantitate ascorbic acid from fruit juices as well as from human plasma by RP-HPLC with UV detection. This has been possible because of the diversity of columns and conditions of analysis available. Chromatographic separation was successfully achieved on a pre-packed Kromasil 100, C/sub 18/ (5 macro m 25 x 0.46) column using acetonitrile water (60:40; v/v) as mobile phase at a flow rate of 0.75 mL/sup -min/ and effluent monitored at 265 nm. The assay was also linear over the concentration range of 0.05-100 micro g/mL/sub -1/, with recovery ranging from 99.0-100.0 % and intra and inter day CV <3 % when applied to the analysis of ascorbic acid from fruit juice available in Pakistan at the time of study Grape fruit, malta, mosami, sweetlemon, fruiter, lemon, lime, custard apple, orange, lemon, guava and papaya juice were found to be very rich in as ascorbic acid, while chikoo, pear, apricot, peach, carrot and some other fruits were found to be poor sources of ascorbic acid. (author)

  7. Exogenous Melatonin Application Delays Senescence of Kiwifruit Leaves by Regulating the Antioxidant Capacity and Biosynthesis of Flavonoids

    Directory of Open Access Journals (Sweden)

    Dong Liang

    2018-04-01

    Full Text Available Melatonin, a multiple signal molecule, plays important roles in delaying senescence during the development of plants. Because few species have been studied for the effect of exogenous melatonin on anti-aging, the plausible mechanism of melatonin of anti-aging effects on other plant species has remained largely unknown. In the present study, the effects of exogenous melatonin on leaf senescence in kiwifruit were examined during natural aging after melatonin (200 μM or water (Control pretreatment. The decreased membrane damage and lower hydrogen peroxide (H2O2 content due to the enhanced scavenging activity of antioxidant enzymes peroxidase (POD, superoxide dismutase (SOD, and catalase (CAT demonstrated that melatonin effectively delayed the aging of kiwifruit leaves. Likewise, owing to up-regulated expression of chlorophyll a/b-binding protein (CAB gene in the sampled leaves pretreated with melatonin, chlorophyll degradation decreased. Therefore, osmoregulatory substances in sampled leaves accumulated (e.g., soluble sugar and soluble protein and seedling cell environment stability was maintained. Simultaneously, melatonin decreased H2O2 concentration owing to increased glutathione (GSH and ascorbate (AsA content, and the expression levels of glutathione reductase (GR, ascorbate peroxidase (APX, monodehydroascorbate reductase (MDAR, dehydroascorbate reductase (DHAR were up-regulated by melatonin application, indicating that the increase of GSH and AsA was attributed to the expression of these genes. In addition, a large amount of flavonoids accumulated in seedlings pretreated with melatonin, and transcript levels of eight genes involved in flavonoid synthesis, including phenylalanine ammonia-lyase (PAL, cinnamate-4-hydroxymate (C4H, chalcone synthase (CHS, flavanone 3-hydroxylase (F3H, flavonol synthase (FNS, leucoanthocyanin reductase (LAR, anthocyanin reductase (ANR, flavonoid 3-O-glucosyltransferase (UFGT were enhanced in response to melatonin

  8. Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry

    Directory of Open Access Journals (Sweden)

    Sushil Kumar

    2012-05-01

    Full Text Available Multiwalled carbon nanotubes were used to modify the surface of a glassy carbon electrode to enhance its electroactivity. Nafion served to immobilise the carbon nanotubes on the electrode surface. The modified electrode was used to develop an analytical method for the analysis of ascorbic acid (AA by square-wave voltammetry (SWV. The oxidation of ascorbic acid at the modified glassy carbon electrode showed a peak potential at 315 mV, about 80 mV lower than that observed at the bare (unmodified electrode. The peak current was about threefold higher than the response at the bare electrode. Replicate measurements of peak currents showed good precision (3% rsd. Peak currents increased with increasing ascorbic acid concentration (dynamic range = 0.0047–5.0 mmol/L and displayed good linearity (R2 = 0.994. The limit of detection was 1.4 μmol/L AA, while the limit of quantitation was 4.7 μmol/L AA. The modified electrode was applied to the determination of the amount of ascorbic acid in four brands of commercial orange-juice products. The measured content agreed well (96–104% with the product label claim for all brands tested. Recovery tests on spiked samples of orange juice showed good recovery (99–104%. The reliability of the SWV method was validated by conducting parallel experiments based on high-performance liquid chromatography (HPLC with absorbance detection. The observed mean AA contents of the commercial orange juice samples obtained by the two methods were compared statistically and were found to have no significant difference (P = 0.05.

  9. Suppression of radiation-induced in vitro carcinogenesis by ascorbic acid

    International Nuclear Information System (INIS)

    Tauchi, Hiroshi; Sawada, Shozo

    1993-01-01

    The effects of ascorbic acid on radiation-induced in vitro carcinogenesis have been reported using neoplastic transformation system of C3H 10T1/2 cells. In these reports, no suppressive effect on X-ray-induced transformation was observed with 6 weeks' administration of ascorbic acid (daily addition for 5 days per week) by Kennedy (1984), whereas apparent suppression was observed with daily addition for 7 days by Yasukawa et al (1989). We have tested the effects of ascorbic acid on 60 Co gamma-ray or 252 Cf fission neutron-induced transformation in Balb/c 3T3 cells. The transformation induced by both types of radiations was markedly suppressed when ascorbic acid was daily added to the medium during first 8 days of the post-irradiation period. If ascorbic acid was added for a total of 8 days but with a day's interruption in the middle, the suppression of transformation was decreased. These results suggest that continuous presence of ascorbic acid for a certain number of days is needed to suppress radiation-induced transformation. Since ascorbic acid also suppressed the promotion of radiation-induced transformation by TPA when both chemicals were added together into the medium, ascorbic acid might act on the promotion stage of transformation. Therefore, the effect of ascorbic acid on the distribution of protein kinase C activity was also investigated, and possible mechanisms of suppression of radiation-induced transformation by ascorbic acid will be discussed. (author)

  10. Interplay between endogenous and exogenous fluctuations in financial markets

    OpenAIRE

    Gontis, Vygintas

    2016-01-01

    We address microscopic, agent based, and macroscopic, stochastic, modeling of the financial markets combining it with the exogenous noise. The interplay between the endogenous dynamics of agents and the exogenous noise is the primary mechanism responsible for the observed long-range dependence and statistical properties of high volatility return intervals. By exogenous noise we mean information flow or/and order flow fluctuations. Numerical results based on the proposed model reveal that the ...

  11. International Environmental Agreements with Endogenous or Exogenous Risk

    OpenAIRE

    Fuhai Hong; Larry Karp

    2014-01-01

    We examine the effect of endogenous and exogenous risk on the equilibrium (expected) membership of an International Environmental Agreement when countries are risk averse. Endogenous risk arises when countries use mixed rather than pure strategies at the participation game, and exogenous risk arises from the inherent uncertainty about the costs and benefits of increased abate- ment. Under endogenous risk, an increase in risk aversion increases expected participation. Under exogenous risk and ...

  12. Independent effects of endogenous and exogenous attention in touch.

    Science.gov (United States)

    Jones, Alexander; Forster, Bettina

    2013-12-01

    Endogenous and exogenous attention in touch have typically been investigated separately. Here we use a double-cueing paradigm manipulating both types of orienting in each trial. Bilateral endogenous cues induced long-lasting facilitation of endogenous attention up to 2 s. However, the exogenous cue only elicited an effect at short intervals. Our results favour a supramodal account of attention and this study provides new insight into how endogenous and exogenous attention operates in the tactile modality.

  13. Ascorbate status modulates reticuloendothelial iron stores and response to deferasirox iron chelation in ascorbate-deficient rats

    DEFF Research Database (Denmark)

    Brewer, Casey; Otto-Duessel, Maya; Lykkesfeldt, Jens

    2012-01-01

    Iron chelation is essential to patients on chronic blood transfusions to prevent toxicity from iron overload and remove excess iron. Deferasirox (DFX) is the most commonly used iron chelator in the United States; however, some patients are relatively refractory to DFX therapy. We postulated...... that vitamin C supplementation would improve the availability of transfusional iron to DFX treatment by promoting iron's redox cycling, increasing its soluble ferrous form and promoting its release from reticuloendothelial cells. Osteogenic dystrophy rats (n = 54) were given iron dextran injections for 10...... 12 weeks of sham chelation. Most importantly, ascorbate supplementation at 2250 ppm improved DFX efficiency, allowing DFX to remove 21% more hepatic iron than ascorbate supplementation with 900 ppm or 150 ppm (p vitamin C status modulates the release of iron from...

  14. Production of ascorbic acid releasing biomaterials for pelvic floor repair.

    Science.gov (United States)

    Mangır, Naşide; Bullock, Anthony J; Roman, Sabiniano; Osman, Nadir; Chapple, Christopher; MacNeil, Sheila

    2016-01-01

    An underlying abnormality in collagen turnover is implied in the occurrence of complications and recurrences after mesh augmented pelvic floor repair surgeries. Ascorbic acid is a potent stimulant of collagen synthesis. The aim of this study is to produce ascorbic acid releasing poly-lactic acid (PLA) scaffolds and evaluate them for their effects on extracellular matrix production and the strength of the materials. Scaffolds which contained either l-ascorbic acid (AA) and Ascorbate-2-Phosphate (A2P) were produced with emulsion electrospinning. The release of both drugs was measured by UV spectrophotometry. Human dermal fibroblasts were seeded on scaffolds and cultured for 2weeks. Cell attachment, viability and total collagen production were evaluated as well as mechanical properties. No significant differences were observed between AA, A2P, Vehicle and PLA scaffolds in terms of fibre diameter and pore size. The encapsulation efficiency and successful release of both AA and A2P were demonstrated. Both AA and A2P containing scaffolds were significantly more hydrophilic and stronger in both dry and wet states compared to PLA scaffolds. Fibroblasts produced more collagen on scaffolds containing either AA or A2P compared to cells grown on control scaffolds. This study is the first to directly compare the two ascorbic acid derivatives in a tissue engineered scaffold and shows that both AA and A2P releasing electrospun PLA scaffolds increased collagen production of fibroblasts to similar extents but AA scaffolds seemed to be more hydrophilic and stronger compared to A2P scaffolds. Mesh augmented surgical repair of the pelvic floor currently relies on non-degradable materials which results in severe complications in some patients. There is an unmet and urgent need for better pelvic floor repair materials. Our current understanding suggests that the ideal material should be able to better integrate into sites of implantation both biologically and mechanically. The impact of

  15. Endogenous and exogenous fluorescence of gastrointestinal tumors: initial clinical observations

    Science.gov (United States)

    Borisova, Ekaterina; Plamenova, Lilia; Keremedchiev, Momchil; Vladimirov, Borislav; Avramov, Latchezar

    2013-03-01

    The limitations of standard endoscopy for detection and evaluation of cancerous changes in gastrointestinal tract (GIT) are significant challenge and initiate development of new diagnostic modalities. Therefore many spectral and optical techniques are applied recently into the clinical practice for obtaining qualitatively and quantitatively new data from gastrointestinal neoplasia with different level of clinical applicability and diagnostic success. One of the most promising approaches is fluorescence detection using naturally existing fluorescent molecules or added fluorescent markers. Deltaaminolevulinic acid / protoporphyrin IX is applied for exogenous fluorescent tumor detection in the upper part of gastrointestinal tract. The 5-ALA is administered per os six hours before measurements at dose 20mg/kg weight. Highpower light-emitting diode at 405 nm is used as a source and the excitation light is passed through the light-guide of standard video-endoscopic system to obtain 2-D visualization. Both kinds of spectra - autofluorescence signals and protoporphyrin IX signal are recorded and stored using a fiber-optic microspectrometer, as in endoscopy instrumental channel a fiber is applied to return information about fluorescence signals. In such way 1-D detection and 2-D visualization of the lesions' fluorescence are received. The results from in vivo detection show significant differentiation between normal and abnormal tissues in 1-D spectroscopic regime, but only moderate discrimination in 2-D imaging.

  16. Exogenously triggered response inhibition in developmental stuttering.

    Science.gov (United States)

    Eggers, Kurt; De Nil, Luc F; Van den Bergh, Bea R H

    2018-06-01

    The purpose of the present study was to examine relations between children's exogenously triggered response inhibition and stuttering. Participants were 18 children who stutter (CWS; mean age = 9;01 years) and 18 children who not stutter (CWNS; mean age = 9;01 years). Participants were matched on age (±3 months) and gender. Response inhibition was assessed by a stop signal task (Verbruggen, Logan, & Stevens, 2008). Results suggest that CWS, compared to CWNS, perform comparable to CWNS in a task where response control is externally triggered. Our findings seem to indicate that previous questionnaire-based findings (Eggers, De Nil, & Van den Bergh, 2010) of a decreased efficiency of response inhibition cannot be generalized to all types of response inhibition. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Extracellular ascorbate stabilization as a result of transplasma electron transfer in Saccharomyces cerevisiae.

    Science.gov (United States)

    Santos-Ocaña, C; Navas, P; Crane, F L; Córdoba, F

    1995-12-01

    The presence of yeast cells in the incubation medium prevents the oxidation of ascrobate catalyzed by copper ions. Ethanol increases ascorbate retention. Pyrazole, an alcohol dehydrogenase inhibitor, prevents ascorbate stabilization by cells. Chelation of copper ions does not account for stabilization, since oxidation rates with broken or boiled cells or conditioned media are similar to control rates in the absence of cells. Protoplast integrity is needed to reach optimal values of stabilization. Chloroquine, a known inhibitor of plasma membrane redox systems, inhibits the ascorbate stabilization, the inhibition being partially reversed by coenzyme Q6. Chloroquine does not inhibit ferricyanide reduction. Growth of yeast in iron-deficient media to increase ferric ion reductase activity also increases the stabilization. In conclusion, extracellular ascorbate stabilization by yeast cells can reflect a coenzyme Q dependent transplasmalemma electron transfer which uses NADH as electron donor. Iron deficiency increases the ascorbate stabilization but the transmembrane ferricyanide reduction system can act independently of ascorbate stabilization.

  18. The preparation and the sustained release of titanium dioxide hollow particles encapsulating L-ascorbic acid

    Science.gov (United States)

    Tominaga, Yoko; Kadota, Kazunori; Shimosaka, Atsuko; Yoshida, Mikio; Oshima, Kotaro; Shirakawa, Yoshiyuki

    2018-05-01

    The preparation of the titanium dioxide hollow particles encapsulating L-ascorbic acid via sol-gel process using inkjet nozzle has been performed, and the sustained release and the effect protecting against degradation of L-ascorbic acid in the particles were investigated. The morphology of titanium dioxide particles was evaluated by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The sustained release and the effect protecting against degradation of L-ascorbic acid were estimated by dialysis bag method in phosphate buffer saline (PBS) (pH = 7.4) as release media. The prepared titanium dioxide particles exhibited spherical porous structures. The particle size distribution of the titanium dioxide particles was uniform. The hollow titanium dioxide particles encapsulating L-ascorbic acid showed the sustained release. It was also found that the degradation of L-ascorbic acid could be inhibited by encapsulating L-ascorbic acid in the titanium dioxide hollow particles.

  19. The effects of exogenous surfactant administration on ventilation-induced inflammation in mouse models of lung injury.

    Science.gov (United States)

    Puntorieri, Valeria; Hiansen, Josh Qua; McCaig, Lynda A; Yao, Li-Juan; Veldhuizen, Ruud A W; Lewis, James F

    2013-11-20

    Mechanical ventilation (MV) is an essential supportive therapy for acute lung injury (ALI); however it can also contribute to systemic inflammation. Since pulmonary surfactant has anti-inflammatory properties, the aim of the study was to investigate the effect of exogenous surfactant administration on ventilation-induced systemic inflammation. Mice were randomized to receive an intra-tracheal instillation of a natural exogenous surfactant preparation (bLES, 50 mg/kg) or no treatment as a control. MV was then performed using the isolated and perfused mouse lung (IPML) set up. This model allowed for lung perfusion during MV. In experiment 1, mice were exposed to mechanical ventilation only (tidal volume =20 mL/kg, 2 hours). In experiment 2, hydrochloric acid or air was instilled intra-tracheally four hours before applying exogenous surfactant and ventilation (tidal volume =5 mL/kg, 2 hours). For both experiments, exogenous surfactant administration led to increased total and functional surfactant in the treated groups compared to the controls. Exogenous surfactant administration in mice exposed to MV only did not affect peak inspiratory pressure (PIP), lung IL-6 levels and the development of perfusate inflammation compared to non-treated controls. Acid injured mice exposed to conventional MV showed elevated PIP, lung IL-6 and protein levels and greater perfusate inflammation compared to air instilled controls. Instillation of exogenous surfactant did not influence the development of lung injury. Moreover, exogenous surfactant was not effective in reducing the concentration of inflammatory cytokines in the perfusate. The data indicates that exogenous surfactant did not mitigate ventilation-induced systemic inflammation in our models. Future studies will focus on altering surfactant composition to improve its immuno-modulating activity.

  20. Exogenous Melatonin Confers Cadmium Tolerance by Counterbalancing the Hydrogen Peroxide Homeostasis in Wheat Seedlings

    Directory of Open Access Journals (Sweden)

    Jun Ni

    2018-03-01

    Full Text Available Melatonin has emerged as a research highlight regarding its important role in regulating plant growth and the adaptation to the environmental stresses. In this study, we investigated how melatonin prevented the cadmium toxicity to wheat seedlings. The results demonstrated that cadmium induced the expression of melatonin biosynthesis-related genes and cause a significant increase of endogenous melatonin level. Melatonin treatment drastically alleviated the cadmium toxicity, resulting in increased plant height, biomass accumulation, and root growth. Cadmium and senescence treatment significantly increased the endogenous level of hydrogen peroxide, which was strictly counterbalanced by melatonin. Furthermore, melatonin treatment caused a significant increase of GSH (reduced glutathione content and the GSH/GSSG (oxidized glutathione ratio. The activities of two key antioxidant enzymes, ascorbate peroxidase (APX and superoxide dismutase (SOD, but not catalase (CAT and peroxidase (POD, were specifically improved by melatonin. Additionally, melatonin not only promoted the primary root growth, but also drastically enhanced the capacity of the seedling roots to degrade the exogenous hydrogen peroxide. These results suggested that melatonin played a key role in maintaining the hydrogen peroxide homeostasis, via regulation of the antioxidant systems. Conclusively, this study revealed a crucial protective role of melatonin in the regulation of cadmium resistance in wheat.

  1. Exogenous Melatonin Confers Cadmium Tolerance by Counterbalancing the Hydrogen Peroxide Homeostasis in Wheat Seedlings.

    Science.gov (United States)

    Ni, Jun; Wang, Qiaojian; Shah, Faheem Afzal; Liu, Wenbo; Wang, Dongdong; Huang, Shengwei; Fu, Songling; Wu, Lifang

    2018-03-30

    Melatonin has emerged as a research highlight regarding its important role in regulating plant growth and the adaptation to the environmental stresses. In this study, we investigated how melatonin prevented the cadmium toxicity to wheat seedlings. The results demonstrated that cadmium induced the expression of melatonin biosynthesis-related genes and cause a significant increase of endogenous melatonin level. Melatonin treatment drastically alleviated the cadmium toxicity, resulting in increased plant height, biomass accumulation, and root growth. Cadmium and senescence treatment significantly increased the endogenous level of hydrogen peroxide, which was strictly counterbalanced by melatonin. Furthermore, melatonin treatment caused a significant increase of GSH (reduced glutathione) content and the GSH/GSSG (oxidized glutathione) ratio. The activities of two key antioxidant enzymes, ascorbate peroxidase (APX) and superoxide dismutase (SOD), but not catalase (CAT) and peroxidase (POD), were specifically improved by melatonin. Additionally, melatonin not only promoted the primary root growth, but also drastically enhanced the capacity of the seedling roots to degrade the exogenous hydrogen peroxide. These results suggested that melatonin played a key role in maintaining the hydrogen peroxide homeostasis, via regulation of the antioxidant systems. Conclusively, this study revealed a crucial protective role of melatonin in the regulation of cadmium resistance in wheat.

  2. Exogenous hydrogen sulfide promotes cell proliferation and differentiation by modulating autophagy in human keratinocytes

    International Nuclear Information System (INIS)

    Xie, Xin; Dai, Hui; Zhuang, Binyu; Chai, Li; Xie, Yanguang; Li, Yuzhen

    2016-01-01

    The effects and the underlying mechanisms of hydrogen sulfide (H 2 S) on keratinocyte proliferation and differentiation are still less known. In the current study, we investigated the effects and the underlying mechanisms of exogenous H 2 S on keratinocyte proliferation and differentiation. Human keratinocytes (HaCaT cells) were treated with various concentrations (0.05, 0.25, 0.5 and 1 mM) of sodium hydrosulfide (NaHS, a donor of H 2 S) for 24 h. A CCK-8 assay was used to assess cell viability. Western blot analysis was performed to determine the expression levels of proteins associated with differentiation and autophagy. Transmission electron microscopy was performed to observe autophagic vacuoles, and flow cytometry was applied to evaluate apoptosis. NaHS promoted the viability, induced the differentiation, and enhanced autophagic activity in a dose-dependent manner in HaCaT cells but had no effect on cell apoptosis. Blockage of autophagy by ATG5 siRNA inhibited NaHS-induced cell proliferation and differentiation. The current study demonstrated that autophagy in response to exogenous H 2 S treatment promoted keratinocyte proliferation and differentiation. Our results provide additional insights into the potential role of autophagy in keratinocyte proliferation and differentiation. - Highlights: • Exogenous H 2 S promotes keratinocyte proliferation and differentiation. • The effects of H 2 S on proliferation and differentiation is modulated by autophagy. • Exogenous H 2 S has no effect on keratinocyte apoptosis.

  3. Neutron scattering and HPLC study on L-ascorbic acid and its degradation

    Energy Technology Data Exchange (ETDEWEB)

    Bellocco, E. [Department of Organic and Biological Chemistry, University of Messina, Messina (Italy)], E-mail: bellocco@isengard.unime.it; Barreca, D.; Lagana, G.; Leuzzi, U. [Department of Organic and Biological Chemistry, University of Messina, Messina (Italy); Migliardo, F.; Torre, R. La; Galli, G. [Department of Physics, University of Messina, Messina (Italy); Galtieri, A. [Department of Organic and Biological Chemistry, University of Messina, Messina (Italy); Minutoli, L.; Squadrito, F. [Department of Clinical and Experimental Medicine and Pharmacology, University of Messina, Messina (Italy)

    2008-04-18

    The present paper shows a systematic dynamic and kinetic study on L-ascorbic acid and its degradation at high temperature. The neutron scattering study allows, through the behavior of quasi-elastic neutron scattering (QENS) spectra, to characterize the diffusive dynamics of L-ascorbic acid in water mixtures. Ascorbic acid undergoes degradation process at high temperature, but the presence of trehalose in solution markedly avoids ascorbic acid loss enhancing its t{sub 1/2} (half life time), as determined by high performance liquid chromatography (HPLC)

  4. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex

    International Nuclear Information System (INIS)

    Arya, S. P.; Mahajan, M.

    1998-01-01

    A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 μg ml -1 . Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C [it

  5. Role Of Ascorbic Acid In Imparting Tolerance To Plants Against Oxidizing Pollutants

    Directory of Open Access Journals (Sweden)

    Priyanka Sharma

    2015-08-01

    Full Text Available Ascorbic acid is an antioxidant in plants which play important role in activation of many physiological and defense mechanisms. The level of ascorbic acid in plants is determinant of its tolerance against the adverse effect of oxidizing pollutants. The present study tries to relate the variation in ascorbic acid content with the tolerance and sensitivity of two selected plant species viz. Azadirachtaindica and Pongamiapinnata by calculating their Air Pollution Tolerance Index APTI during winter season from November to March in the urban city Delhi of North India. Moreover ascorbic acid is also an important part of chloroplast it protects different components of photosynthetic system from oxidative stress. Thus to understand the role of ascorbic acid in imparting tolerance to plants against oxidizing pollutants the changes in chlorophyll content of the selected plant species with variation in ambient ozone concentration was analysed. It was found that as per APTI values Azadirachta sp. came under tolerant range with highest ascorbic acid content whereas Pongamia sp. was under intermediate range with less ascorbic acid content. It was statistically established that ozone has no significant relation with chlorophyll content of Azadirachta sp. which has the highest ascorbic acid content. Whereas ambient ozone concentrations showed significant negative relation with the chlorophyll content of Pongamia sp. p 0.05. Thus it was observed that the plants with high ascorbic acid content are tolerant and have greater ability to remediate pollutants.

  6. Measurement of binding of ascorbic acid to myrosinase by rate of dialysis

    International Nuclear Information System (INIS)

    Ohtsuru, Masaru; Hata, Tadao

    1975-01-01

    The activation mechanism of myrosinase by L-ascorbic acid depends on the slight conformational change of enzyme protein induced by ascorbic acid. Ascorbic acid binds to enzyme like Michaelis-complex, and then the value of Km had been evaluated to be 1 x 10 -3 M. The authors determined the binding constant and the number of binding sites using dialysis rate technique. Rate dialysis was carried out with a dialysis cell, and the ordinary cellophane tubing membrane was used. ( 14 C) - ascorbic acid was added, and counted by liquid scintillation counting. By the time course of two dialysis rate measurement with and without enzyme. The concentrations of free and bound ascorbic acids were counted. From the results, the enzyme was activated to the maximum level at 10 -3 M of ascorbic acid, and four molecules of ascorbic acid bound to the enzyme on Kd=0.1x10 -4 M. However, when more than 4 molecules of L-ascorbic acid bound to the enzyme, Kd increased to 0.9x10 -4 M, and L-ascorbic acid acted as an inhibitor. (Kubatake, H.)

  7. The kinetics of oxidation of bilirubin and ascorbic acid in solution

    Science.gov (United States)

    Solomonov, A. V.; Rumyantsev, E. V.; Kochergin, B. A.; Antina, E. V.

    2012-07-01

    The results of a comparative study of the oxidation of bilirubin, ascorbic acid, and their mixture in aqueous solutions under the action of air oxygen and hydrogen peroxide are presented. The observed and true rate constants for the oxidation reactions were determined. It was shown that the oxidation of tetrapyrrole pigment occurred under these conditions bypassing the stage of biliverdin formation to monopyrrole products. Simultaneous oxidation of bilirubin and ascorbic acid was shown to be accompanied by the inhibition of ascorbic acid oxidation by bilirubin, whereas ascorbic acid itself activated the oxidation of bilirubin.

  8. Neutron scattering and HPLC study on L-ascorbic acid and its degradation

    International Nuclear Information System (INIS)

    Bellocco, E.; Barreca, D.; Lagana, G.; Leuzzi, U.; Migliardo, F.; Torre, R. La; Galli, G.; Galtieri, A.; Minutoli, L.; Squadrito, F.

    2008-01-01

    The present paper shows a systematic dynamic and kinetic study on L-ascorbic acid and its degradation at high temperature. The neutron scattering study allows, through the behavior of quasi-elastic neutron scattering (QENS) spectra, to characterize the diffusive dynamics of L-ascorbic acid in water mixtures. Ascorbic acid undergoes degradation process at high temperature, but the presence of trehalose in solution markedly avoids ascorbic acid loss enhancing its t 1/2 (half life time), as determined by high performance liquid chromatography (HPLC)

  9. The effects of exogenous proline and osmotic stress on morpho ...

    African Journals Online (AJOL)

    USER

    2010-06-21

    Jun 21, 2010 ... For evaluation of growth parameters of strawberry callus under osmotic stress and exogenous proline, embryonic calli were transferred to Murashige and Skoog (MS) medium containing four sucrose. (osmotic stress) treatments including 3, 6, 9 and 12% and various concentrations of exogenous L- proline ...

  10. The effects of exogenous proline and osmotic stress on morpho ...

    African Journals Online (AJOL)

    For evaluation of growth parameters of strawberry callus under osmotic stress and exogenous proline, embryonic calli were transferred to Murashige and Skoog (MS) medium containing four sucrose (osmotic stress) treatments including 3, 6, 9 and 12% and various concentrations of exogenous Lproline (0, 2.5, 5 and 10 ...

  11. Effect Of Exogenous Progesterone On Blood Chemistry Of Large ...

    African Journals Online (AJOL)

    Exogenous hormones are major economic factors in swine production. This study evaluate the effects of exogenous administration of progesterone on the blood chemistry of pigs.Experiment involved weekly injections of progesterone to 24 pigs (12 males and 12 females)from day old to 24 weeks and only corn oil to another ...

  12. The Endogenous-Exogenous Partition in Attribution Theory

    Science.gov (United States)

    Kruglanski, Arie W.

    1975-01-01

    Within lay explanation of actions, several significant inferences are assumed to follow from the partition between endogenous and exogenous attributions. An endogenous action is judged to constitute an end in itself; an exogenous action is judged to serve as a means to some further end. (Editor/RK)

  13. The Effects of Foliar Application of Benzyl Adenine, Ascorbic Acid and Thiamine on Some Morphological and Biochemical Characteristics of Petunia (Petunia hybrida

    Directory of Open Access Journals (Sweden)

    M. Salehi

    2016-05-01

    Full Text Available The improvement of growth and flowering of petunia as one of the most popular and cultivated bedding plants in Iran, is of significant importance. Thus, a CRD experiment with five replications was conducted at the Research Greenhouse of Shahid Bahonar University, Kerman, Iran.  From 48 days after sowing, when the seedlings had 5-6 true leaves, the seedlings were sprayed with  thiamine (0 and 100 mgL-1, ascorbic acid (0 and 100 mg L-1 and benzyl adenine (0 and 200 mg L-1 at 4 steps during  growth and development. The results indicated that the treatment of ascorbic acid with thiamine and benzyl adenine led to 2.5 and 3.5-fold increases in the number and length of lateral shoots compared to control treatment. The greatest fresh weight was obtained with ascorbic acid with thiamine and benzyl adenine treatment which led to a 2.5-fold increase in this trait, compared to the control. The highest dry weight was achieved in benzyl adenine treatment. The greatest vase-life and flower diameter were found with ascorbic acid (100 mg L-1, thiamine (100 mg L-1 and benzyl adenine (200 mg L-1 treatments in an extent that the flower longevity and diameter were increased by 83% and 72%, respectively, in comparison to control. Furthermore, chlorophyll a, chlorophyll b, total chlorophyll, carotenoids and reduced sugars concentrations were significantly increased by the foliar-applied compounds compared to control.

  14. Highly selective determination of dopamine in the presence of ascorbic acid and serotonin at glassy carbon electrodes modified with carbon nanotubes dispersed in polyethylenimine.

    Science.gov (United States)

    Rodríguez, Marcela C; Rubianes, María D; Rivas, Gustavo A

    2008-11-01

    We report the highly selective and sensitive voltammetric dopamine quantification in the presence of ascorbic acid and serotonin by using glassy carbon electrodes modified with a dispersion of multi-wall carbon nanotubes (MWCNT) in polyethylenimine, PEI (GCE/MWCNT-PEI). The electrocatalytic activity of the MWCNT deposited on the glassy carbon electrode has allowed an important decrease in the overvoltages for the oxidation of ascorbic acid and dopamine, making possible a clear definition of dopamine, serotonin and ascorbic acid oxidation processes. The sensitivities for dopamine in the presence and absence of 1.0 mM ascorbic acid and serotonin were (2.18 +/- 0.03) x 10(5) microAM(-1) (r = 0.9998); and (2.10 +/- 0.07) x 10(5) miroAM(-1) (r=0.9985), respectively, demonstrating the excellent performance of the GCE/MWCNT-PEI. The detection limit for dopamine in the mixture was 9.2 x 10(-7) M. The R. S. D. for the determination of 50 microM dopamine using four different electrodes was 3.9% when modified with the same MWCNT/PEI dispersion, and 4.6% when using four different dispersions. The modified electrode has been successfully applied for recovery assays of dopamine in human blood serum. Therefore, the new sensor represents an interesting and promising alternative for the electrochemical quantification of neurotransmitters and other analytes of clinical interest.

  15. Reduction of nitrobenzene with alkaline ascorbic acid: Kinetics and pathways

    International Nuclear Information System (INIS)

    Liang, Chenju; Lin, Ya-Ting; Shiu, Jia-Wei

    2016-01-01

    Highlights: • Alkaline ascorbic acid (a.k.a. vitamin C) is capable of reductively degrading NB. • The pH above the pK_a_2 of ascorbic acid increases reductive electron transfer to NB. • The rate equation for the reactions between NB and AA is determined. • NSB, AZOXY, and AZO are identified as intermediates and aniline as a final product. • Alkaline pH is essential for AA remediation of NB contaminated soils. - Abstract: Alkaline ascorbic acid (AA) exhibits the potential to reductively degrade nitrobenzene (NB), which is the simplest of the nitroaromatic compounds. The nitro group (NO_2"−) of NB has a +III oxidation state of the N atom and tends to gain electrons. The effect of alkaline pH ranging from 9 to 13 was initially assessed and the results demonstrated that the solution pH, when approaching or above the pK_a_2 of AA (11.79), would increase reductive electron transfer to NB. The rate equation for the reactions between NB and AA at pH 12 can be described as r = ((0.89 ± 0.11) × 10"−"4 mM"1"−"("a "+ "b") h"−"1) × [NB]"a "= "1"."3"5 "± "0"."1"0[AA]"b "= "0"."8"9 "± "0"."0"1. The GC/MS analytical method identified nitrosobenzene, azoxybenzene, and azobenzene as NB reduction intermediates, and aniline (AN) as a final product. These experimental results indicate that the alkaline AA reduction of NB to AN mainly proceeds via the direct route, consisting of a series of two-electron or four-electron transfers, and the condensation reaction plays a minor route. Preliminary evaluation of the remediation of spiked NB contaminated soils revealed that maintenance of alkaline pH and a higher water to soil ratio are essential for a successful alkaline AA application.

  16. Distinct roles of exogenous opioid agonists and endogenous opioid peptides in the peripheral control of neuropathy-triggered heat pain.

    Science.gov (United States)

    Labuz, Dominika; Celik, Melih Ö; Zimmer, Andreas; Machelska, Halina

    2016-09-08

    Neuropathic pain often results from peripheral nerve damage, which can involve immune response. Local leukocyte-derived opioid peptides or exogenous opioid agonists inhibit neuropathy-induced mechanical hypersensitivity in animal models. Since neuropathic pain can also be augmented by heat, in this study we investigated the role of opioids in the modulation of neuropathy-evoked heat hypersensitivity. We used a chronic constriction injury of the sciatic nerve in wild-type and opioid peptide-knockout mice, and tested opioid effects in heat and mechanical hypersensitivity using Hargreaves and von Frey tests, respectively. We found that although perineural exogenous opioid agonists, including peptidergic ligands, were effective, the endogenous opioid peptides β-endorphin, Met-enkephalin and dynorphin A did not alleviate heat hypersensitivity. Specifically, corticotropin-releasing factor, an agent triggering opioid peptide secretion from leukocytes, applied perineurally did not attenuate heat hypersensitivity in wild-type mice. Exogenous opioids, also shown to release opioid peptides via activation of leukocyte opioid receptors, were equally analgesic in wild-type and opioid peptide-knockout mice, indicating that endogenous opioids do not contribute to exogenous opioid analgesia in heat hypersensitivity. Furthermore, exogenously applied opioid peptides were ineffective as well. Conversely, opioid peptides relieved mechanical hypersensitivity. Thus, both opioid type and sensory modality may determine the outcome of neuropathic pain treatment.

  17. Ascorbic acid and melatonin reduce heat-induced performance inhibition and oxidative stress in Japanese quails.

    Science.gov (United States)

    Sahin, N; Onderci, M; Sahin, K; Gursu, M F; Smith, M O

    2004-02-01

    1. The effects of ascorbic acid (L-ascorbic acid) and melatonin supplementation on performance, carcase characteristics, malondialdehyde (MDA) as lipid peroxidation indicator, ascorbic acid, retinol, tocopherol and mineral status in the Japanese quail (Coturnix coturnix japonica) exposed to high ambient temperature were evaluated. 2. Two hundred and forty Japanese quails (10 d old) were randomly assigned to 8 treatment groups consisting of 10 replicates of three birds each. The birds were kept in a temperature-controlled room at 22 degrees C (Thermoneutral, TN groups) or 34 degrees C (for 8 h/d; 09:00 to 17:00 h; Heat stress, HS groups). Birds in both TN and HS were fed either a basal (control) diet or the basal diet supplemented with 250 mg of L-ascorbic acid/kg of diet (Ascorbic acid group), 40 mg of melatonin/kg of diet (Melatonin group) or both (Ascorbic acid + Melatonin group). 3. Supplementing heat-stressed quails with ascorbic acid and melatonin improved performance compared with the control group. Effects generally were greatest in quails supplemented with both ascorbic acid and melatonin. 4. Although supplementation did not consistently restore the concentrations of serum ascorbic acid, retinol and tocopherol to those of TN groups, these concentrations increased significantly with supplementation. Furthermore, serum and liver MDA and serum cholesterol and glucose concentrations were lower in the supplemented groups than in the heat-stressed controls. 5. Within each environment, excretion of Ca, P, Mg, Zn, Fe and Cr were lowest in the combination group and, in all cases, highest in the HS group. Interactions between diet and temperature were detected for live weight gain, cold carcase weight, MDA, ascorbic acid, tocopherol concentrations and excretion of zinc. 6. The results of the study indicate that ascorbic acid and melatonin supplementation attenuate the decline in performance and antioxidant and mineral status caused by heat stress and such

  18. Thermal stability of L-ascorbic acid and ascorbic acid oxidase in broccoli (Brassica oleracea var. italica).

    Science.gov (United States)

    Munyaka, Ann Wambui; Makule, Edna Edward; Oey, Indrawati; Van Loey, Ann; Hendrickx, Marc

    2010-05-01

    The thermal stability of vitamin C (including l-ascorbic acid [l-AA] and dehydroascorbic acid [DHAA]) in crushed broccoli was evaluated in the temperature range of 30 to 90 degrees C whereas that of ascorbic acid oxidase (AAO) was evaluated in the temperature range of 20 to 95 degrees C. Thermal treatments (for 15 min) of crushed broccoli at 30 to 60 degrees C resulted in conversion of l-AA to DHAA whereas treatments at 70 to 90 degrees C retained vitamin C as l-AA. These observations indicated that enzymes (for example, AAO) could play a major role in the initial phase (that is, oxidation of l-AA to DHAA) of vitamin C degradation in broccoli. Consequently, a study to evaluate the temperature-time conditions that could result in AAO inactivation in broccoli was carried out. In this study, higher AAO activity was observed in broccoli florets than stalks. During thermal treatments for 10 min, AAO in broccoli florets and stalks was stable until around 50 degrees C. A 10-min thermal treatment at 80 degrees C almost completely inactivated AAO in broccoli. AAO inactivation followed 1st order kinetics in the temperature range of 55 to 65 degrees C. Based on this study, a thermal treatment above 70 degrees C is recommended for crushed vegetable products to prevent oxidation of l-AA to DHAA, the onset of vitamin C degradation. The results reported in this study are applicable for both domestic and industrial processing of vegetables into products such as juices, soups, and purees. In this report, we have demonstrated that processing crushed broccoli in a temperature range of 30 to 60 degrees C could result in the conversion of l-ascorbic acid to dehydroascorbic (DHAA), a very important reaction in regard to vitamin C degradation because DHAA could be easily converted to other compounds that do not have the biological activity of vitamin C.

  19. Association between exogenous testosterone and cardiovascular events: an overview of systematic reviews.

    Science.gov (United States)

    Onasanya, Oluwadamilola; Iyer, Geetha; Lucas, Eleanor; Lin, Dora; Singh, Sonal; Alexander, G Caleb

    2016-11-01

    Given the conflicting evidence regarding the association between exogenous testosterone and cardiovascular events, we systematically assessed published systematic reviews for evidence of the association between exogenous testosterone and cardiovascular events. We searched PubMed, MEDLINE, Embase, Cochrane Collaboration Clinical Trials, ClinicalTrials.gov, and the US Food and Drug Administration website for systematic reviews of randomised controlled trials published up to July 19, 2016. Two independent reviewers screened 954 full texts from 29 335 abstracts to identify systematic reviews of randomised controlled trials in which the cardiovascular effects of exogenous testosterone on men aged 18 years or older were examined. We extracted data for study characteristics, analytic methods, and key findings, and applied the AMSTAR (A Measurement Tool to Assess Systematic Reviews) checklist to assess methodological quality of each review. Our primary outcome measure was the direction and magnitude of association between exogenous testosterone and cardiovascular events. We identified seven reviews and meta-analyses, which had substantial clinical heterogeneity, differing statistical methods, and variable methodological quality and quality of data abstraction. AMSTAR scores ranged from 3 to 9 out of 11. Six systematic reviews that each included a meta-analysis showed no significant association between exogenous testosterone and cardiovascular events, with summary estimates ranging from 1·07 to 1·82 and imprecise confidence intervals. Two of these six meta-analyses showed increased risk in subgroup analyses of oral testosterone and men aged 65 years or older during their first treatment year. One meta-analysis showed a significant association between exogenous testosterone and cardiovascular events, in men aged 18 years or older generally, with a summary estimate of 1·54 (95% CI 1·09-2·18). Our optimal information size analysis showed that any randomised controlled

  20. CENTRAL SEROUS CHORIORETINOPATHY IN POSTMENOPAUSAL WOMEN RECEIVING EXOGENOUS TESTOSTERONE.

    Science.gov (United States)

    Conway, Mandi D; Noble, Jason A; Peyman, Gholam A

    2017-01-01

    Central serous chorioretinopathy (CSR) is a serous detachment of the neurosensory retina commonly associated with male sex, Type-A personality and corticosteroid use. Exogenous administration of androgens and development of CSR in men has been reported. Only one case of CSR in a postmenopausal woman receiving exogenous androgen therapy has been reported. The authors describe three cases of chronic CSR in postmenopausal women receiving exogenous testosterone therapy. Diagnosis was based on characteristic clinical, fluorescein angiographic, and optical coherence tomography findings. The three women were being treated with exogenous testosterone and progesterone therapy for symptoms of menopause and libido loss. Average age at presentation was 54.7 years (53-56 years), average duration of exogenous androgen use was 61 months (36-87 months), with average 19.7-month follow-up. Resolution of symptoms seemed correlated with cessation of androgen use despite treatment with oscillatory photodynamic therapy and intravitreal pharmacotherapy with antivascular endothelial growth factor agents. Exogenous testosterone is increasingly prescribed for menopausal symptoms and libido loss. Treatment with oscillatory photodynamic therapy, supplemental bevacizumab intravitreal pharmacotherapy, and cessation of exogenous androgen therapy was successful in three cases of chronic, therapy-resistant CSR. Ophthalmologists should inquire about androgen usage in patients who present with CSR, especially in the setting of therapy resistance.

  1. Effects of cytochalasin B on the uptake of ascorbic acid and glucose by 3T3 fibroblasts: Mechanism of impaired ascorbate transport in diabetes

    International Nuclear Information System (INIS)

    Fay, M.J.; Bush, M.J.; Verlangieri, A.J.

    1990-01-01

    Hyperglycemia and/or hypoinsulinemia have been found to inhibit L-ascorbic acid cellular transport. The resultant decrease in intracellular ascorbic acid may de-inhibit aryl sulfatase B and increase degradation of sulfated glycosaminoglycans (sGAG). This could lead to a degeneration of the extracellular matrix and result in increased intimal permeability, the initiating event in atherosclerosis. The present studies show that the glucose transport inhibitor cytochalasin B blocked the uptake of 3 H-2-deoxy-D-glucose by mouse 3T3 fibroblasts. Cytochalasin B also blocked the uptake of 14 C-L-ascorbic acid. The results of these studies further support the hypothesis that glucose and ascorbate share a common transport system. This may have important implications concerning the vascular pathology associated with diabetes mellitus

  2. THE EFFECT OF ASCORBIC ACID ON PATHOHISTOLOGICAL TUMOR CHARACTERISTICS AND PHENOTYPE CHARACTERISTICS OF LYMPHOCYTES DURING THE DEVELOPMENT OF EXPERIMENTAL MAMMARY CARCINOMA IN MICE

    Directory of Open Access Journals (Sweden)

    Voja Pavlovic

    2005-04-01

    Full Text Available TIn our previous study we demonstrated that high doses of ascorbic acid prolonged the survival of mice with experimental mammary carcinoma. In this work we studied, ussing the same model, pathohistological characteristics of the tumor and phenotypic changes of lymphocyte subsets in the spleen. Experiments were performed on CBA/H mice. The growh of experimental tumor was induced by injection of mammary adenocarcinoma cells intramuscularly at the femoral region of mice. The animals were divided into control group and three experimental groups (I, II and III. Mice from experimental groups were treated peroraly with 10, 100 and 1000 mg/kg body mass (b.m. of ascorbic acid, respectively, whereas control mice received physiological saline. Mice were sacrified after 7, 14 and 21 days from the beginning of the experiment. Total tumor mass and its pathohistological characteristics, spleen mass and cellularity as well as relative and total numbers of T cells, B cells and T cell subsets (CD4+ and CD8+ in the spleen, were analyzed. High doses of ascorbic acid decreased tumor mass, stimulated proliferation of fibroblasts and formation of capsula arround the tumor, induced tumor necrosis and increased the number of tumor infiltrating lymphocytes. Changes of lymphocyte subsets and their numbers varied depending on the applied dose of ascorbic acid and the time elapsed following tumor induction. The most prominent changes, manifested by an increase in the number of CD4+ T cells were observed on the 14th day in II experimental group. Our results suggest that the beneficial effect of ascorbic acid on experimental tumorogenesis in our model was the consequence of its influence on the tumor and on the immune system.

  3. Pharmacological ascorbate and ionizing radiation (IR increase labile iron in pancreatic cancer

    Directory of Open Access Journals (Sweden)

    Justin C. Moser

    2014-01-01

    Full Text Available Labile iron, i.e. iron that is weakly bound and is relatively unrestricted in its redox activity, has been implicated in both the pathogenesis as well as treatment of cancer. Two cancer treatments where labile iron may contribute to their mechanism of action are pharmacological ascorbate and ionizing radiation (IR. Pharmacological ascorbate has been shown to have tumor-specific toxic effects due to the formation of hydrogen peroxide. By catalyzing the oxidation of ascorbate, labile iron can enhance the rate of formation of hydrogen peroxide; labile iron can also react with hydrogen peroxide. Here we have investigated the magnitude of the labile iron pool in tumor and normal tissue. We also examined the ability of pharmacological ascorbate and IR to change the size of the labile iron pool. Although a significant amount of labile iron was seen in tumors (MIA PaCa-2 cells in athymic nude mice, higher levels were seen in murine tissues that were not susceptible to pharmacological ascorbate. Pharmacological ascorbate and irradiation were shown to increase the labile iron in tumor homogenates from this murine model of pancreatic cancer. As both IR and pharmacological ascorbate may rely on labile iron for their effects on tumor tissues, our data suggest that pharmacological ascorbate could be used as a radio-sensitizing agent for some radio-resistant tumors.

  4. Ascorbic acid effects on in vitro maturation of mouse oocyte with or ...

    African Journals Online (AJOL)

    Ascorbic acid has long been associated with fertility. This study was designed to determine the effects of ascorbic acid on in vitro maturation of mouse oocyte with or without cumulus cells. In this study, 508 denuded oocytes (DOs) and 527 cumulus–oocyte complexes (COCs) from mice stimulated with pregnant mare's serum ...

  5. Effect of docosahexaenoic acid and ascorbate on peroxidation of retinal membranes of ODS rats.

    Science.gov (United States)

    Wang, Jin-Ye; Sekine, Seiji; Saito, Morio

    2003-04-01

    Mutant male osteogenic disorder Shionogi (ODS) rats, unable to synthesize ascorbic acid, were fed diets containing a high content of docosahexaenoic acid (DHA) and different amounts of ascorbic acid, to study the effect of DHA on peroxidative susceptibility of the retina and possible antioxidant action of ascorbic acid. ODS rats were fed from 7 weeks of age with diets containing high DHA (6.4% of total energy). A control group received a diet high in linoleic acid. The diets also contained varying amounts of ascorbic acid. Fatty acid compositions and phospholipid hydroperoxides in rod outer segment (ROS) membranes, and retinal ascorbic acid were analyzed. DHA in ROS membranes was significantly increased in rats fed high DHA, compared with the linoleic acid diet. Levels of phospholipid hydroperoxides in the DHA-fed rats were significantly higher than the linoleic acid-fed rats. Ascorbic acid supplementation did not suppress the phospholipid hydroperoxide levels after a high DHA diet, even when the supplement increased the content of retinal ascorbic acid. In conclusion, high DHA feeding induced a marked increase of phospholipid hydroperoxides in ROS membranes of ODS rats. Supplementation of ascorbic acid did not reverse this increase.

  6. Mechanism of ascorbic acid interference in biochemical tests that use peroxide and peroxidase to generate chromophore.

    Science.gov (United States)

    Martinello, Flávia; Luiz da Silva, Edson

    2006-11-01

    Ascorbic acid interferes negatively in peroxidase-based tests (Trinder method). However, the precise mechanism remains unclear for tests that use peroxide, a phenolic compound and 4-aminophenazone (4-AP). We determined the chemical mechanism of this interference, by examining the effects of ascorbic acid in the reaction kinetics of the production and reduction of the oxidized chromophore in urate, cholesterol, triglyceride and glucose tests. Reaction of ascorbic acid with the Trinder method constituents was also verified. Ascorbic acid interfered stoichiometrically with all tests studied. However, it had two distinct effects on the reaction rate. In the urate test, ascorbic acid decreased the chromophore formation with no change in its production kinetics. In contrast, in cholesterol, triglyceride and glucose tests, an increase in the lag phase of color development occurred. Of all the Trinder constituents, only peroxide reverted the interference. In addition, ascorbic acid did not interfere with oxidase activity nor reduce significantly the chromophore formed. Peroxide depletion was the predominant chemical mechanism of ascorbic acid interference in the Trinder method with phenolics and 4-AP. Distinctive effects of ascorbic acid on the reaction kinetics of urate, cholesterol, glucose and triglyceride might be due to the rate of peroxide production by oxidases.

  7. Control of lethal browning by using ascorbic acid on shoot tip ...

    African Journals Online (AJOL)

    The use of ascorbic acid during explants preparation and the effect of different concentrations of ascorbic acid in controlling lethal browning and survival of the explants in local banana cv. Mzuzu banana were investigated. The explants were taken from young suckers. The shoot tips were cultured on Murashige and Skoog's ...

  8. Ascorbic acid metabolism in the organism under the lack of oxygen supply to the tissues

    Directory of Open Access Journals (Sweden)

    Sergiy Petrov

    2017-06-01

    Full Text Available The number and ratios of the metabolites of vitamin C - ascorbic, dehydroascorbic and diketogulonic acids were studied under the action of closed space hypoxia, acute blood loss and during sleep – the conditions associated with various oxygen saturation of the organism. It was found that in case of closed space hypoxia, the level of ascorbic and diketogulonic acid decreased with a simultaneous increase in the content of dehydroascorbic acid in the heart and brain. Acute blood loss resulted in decrease in the level of all metabolites of ascorbic acid. During sleep, the level of ascorbic acid metabolites increased. The ratio of vitamin-active metabolites to vitamin-inactive form of ascorbic acid in case of closed space hypoxia and acute blood loss decreased, and during sleep – it did not change significantly.

  9. Salivary ascorbic acid levels in betel quid chewers: A biochemical study

    Directory of Open Access Journals (Sweden)

    Shishir R Shetty

    2013-01-01

    Full Text Available Background: Quid chewing practice has been a part of our tradition since centuries with little known evidence of oral cancer. However, recent trends show a rise in occurrence of oral cancer often associated with tobacco and arecanut usage. Ascorbic acid is an important salivary antioxidant. Betel leaf which is used in quid is known to contain ascorbic acid. Aim: The aim of our study was to assess the salivary levels of ascorbic acid in traditional quid chewers so as to determine whether the betel leaf has protective antioxidant action. Materials and Methods: Salivary ascorbic acid levels of 60 subjects were estimated using the Dinitrophenyl hydrazine method. Results: The results revealed that quid chewers who used betel leaf had higher salivary ascorbic acid content compared to nonbetel leaf quid chewers. This could possibly be due to the protective antioxidants in the betel leaf.

  10. Salivary ascorbic acid levels in betel quid chewers: A biochemical study.

    Science.gov (United States)

    Shetty, Shishir R; Babu, Subhas; Kumari, Suchetha; Prasad, Rajendra; Bhat, Supriya; Fazil, K A

    2013-07-01

    Quid chewing practice has been a part of our tradition since centuries with little known evidence of oral cancer. However, recent trends show a rise in occurrence of oral cancer often associated with tobacco and arecanut usage. Ascorbic acid is an important salivary antioxidant. Betel leaf which is used in quid is known to contain ascorbic acid. The aim of our study was to assess the salivary levels of ascorbic acid in traditional quid chewers so as to determine whether the betel leaf has protective antioxidant action. Salivary ascorbic acid levels of 60 subjects were estimated using the Dinitrophenyl hydrazine method. The results revealed that quid chewers who used betel leaf had higher salivary ascorbic acid content compared to nonbetel leaf quid chewers. This could possibly be due to the protective antioxidants in the betel leaf.

  11. Induction of virus resistance by exogenous application of double-stranded RNA.

    Science.gov (United States)

    Mitter, Neena; Worrall, Elizabeth A; Robinson, Karl E; Xu, Zhi Ping; Carroll, Bernard J

    2017-10-01

    Exogenous application of double-stranded RNA (dsRNA) for virus resistance in plants represents a very attractive alternative to virus resistant transgenic crops or pesticides targeting virus vectors. However, the instability of dsRNA sprayed onto plants is a major challenge as spraying naked dsRNA onto plants provides protection against homologous viruses for only 5 days. Innovative approaches, such as the use of nanoparticles as carriers of dsRNA for improved stability and sustained release, are emerging as key disruptive technologies. Knowledge is still limited about the mechanism of entry, transport and processing of exogenously applied dsRNA in plants. Cost of dsRNA and regulatory framework will be key influencers towards practical adoption of this technology. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Effect of exogenous IAA on radiation-induced seedling growth in rice

    International Nuclear Information System (INIS)

    Bhattacharya, Shakuntala; Shama Rao, H.K.

    1978-01-01

    Rice seeds of var. D-6-2-2 were used to ascertain the interaction between exogenous IAA and low and high dose of γ-rays on seedling growth. Low doses of radiation (1,2 kR) and low concentrations of IAA(5,10 ppm) stimulated growth when applied independently. However, they proved inhibitory in combination, indicating the possibility of native IAA involvement at optimum level in radiation-induced stimulation. At a higher dose (5 kR), higher concentrations of exogenous IAA (50,100 ppm) resulted in a significant growth recovery over control. These results suggest that low doses of ionizing radiations probably accelerate the IAA synthesizing system leading to stimulation. (author)

  13. Degradation of L-Ascorbic Acid in the Amorphous Solid State.

    Science.gov (United States)

    Sanchez, Juan O; Ismail, Yahya; Christina, Belinda; Mauer, Lisa J

    2018-03-01

    Ascorbic acid degradation in amorphous solid dispersions was compared to its degradation in the crystalline state. Physical blends and lyophiles of ascorbic acid and polymers (pectins and polyvinylpyrrolidone [PVP]) were prepared initially at 50:50 (w/w), with further studies using the polymer that best inhibited ascorbic acid crystallization in the lyophiles in 14 vitamin : PVP ratios. Samples were stored in controlled environments (25 to 60 °C, 0% to 23% RH) for 1 mo and analyzed periodically to track the physical appearance, change in moisture content, physical state (powder x-ray diffraction and polarized light microscopy), and vitamin loss (high performance liquid chromatography) over time. The glass transition temperatures of select samples were determined using differential scanning calorimetry, and moisture sorption profiles were generated. Ascorbic acid in the amorphous form, even in the glassy amorphous state, was more labile than in the crystalline form in some formulations at the highest storage temperature. Lyophiles stored at 25 and 40 °C and those in which ascorbic acid had crystallized at 60 °C (≥70% ascorbic acid : PVP) had no significant difference in vitamin loss (P > 0.05) relative to physical blend controls, and the length of storage had little effect. At 60 °C, amorphous ascorbic acid lyophiles (≤60% ascorbic acid : PVP) lost significantly more vitamin (P vitamin loss significantly increased over time. In these lyophiles, vitamin degradation also significantly increased (P vitamins are naturally present or added at low concentrations and production practices may promote amorphization of the vitamin. Vitamin C is one of the most unstable vitamins in foods. This study documents that amorphous ascorbic acid is less stable than crystalline ascorbic acid in some environments (for example, higher temperatures within 1 wk), especially when the vitamin is present at low concentrations in a product. These findings increase the understanding of

  14. Increasing Thai Catfish's Immunity (Pangasius hypophthalmus Fowler Using Ascorbic Acid

    Directory of Open Access Journals (Sweden)

    , Ilmiah

    2007-08-01

    Full Text Available ABSTRACTAn experiment to determine Thai catfish's (Pangasius hypophthalmus Fowler immunity was carried out using different levels of ascorbic acid (0, 1.000, 2.000 and 3.000 mg/kg feed.  Fish of 15-20 g in weight were kept in aquaria for 6 weeks with density of 15 fish/aquaria.  Feed was given at 5-10 % of total biomass with frequency of three times a day.  The blood sampling was taken every week and the challenge test with Aeromonas hydrophila (106cells/mm3 injection intramuscular was done on the 30th day.   The result of this experiment shown that feed with ascorbic acid of 2.000 mg/kg was elevated the cellular responses such as: leucocyte total (34.850 cels/mm3, differential of leucocyte (lymphocyte: 72,2%, monocyte: 8,0%, neutrophyl: 7,8%, phagocytic index (13% and humoral response (titre antibody: 0.829 serum aglutination unit, which at the same time proves high level of survival rate against the artificial injection using A. hydrophila. Key words :  Ascorbic acid, fish immunity, Thai catfish, Pangasius hypophthalmus.   ABSTRAK Suatu penelitian telah dilakukan di laboratorium dengan menggunakan ikan jambal Siam (Pangasius hypophthalmus Fowler untuk melihat tingkat kekebalan ikan dengan menambahkan vitamin C pada pakan (0, 1.000, 2.000 dan 3.000 mg/kg pakan.  Ikan jambal Siam ukuran 15-20 g dipelihara dalam aquarium selama 6 minggu dengan kepadatan 15 ekor/wadah.  Pemberian pakan dilakukan 3 kali sehari sebanyak 5-10% dari bobot biomasa, pengambilan contoh darah dilakukan setiap minggu dan uji tantang dilakukan pada hari ke-30 dengan bakteri Aeromonas hydrophila (106 sel/mm3 secara intramuskular.  Hasil penelitian menunjukkan bahwa penambahan vitamin C sebanyak 2.000 mg/kg pakan menyebabkan meningkatnya respon seluler antara lain: total lekosit (34.850 sel/mm3, jenis lekosit (limfosit: 72,2%, monosit: 8,0%, netrofil: 7,7% dan trombosit: 17,6% indeks fagositik 13% dan respon humoral (titer antibodi: 0,829 unit serum aglutinasi

  15. Reduction of nitrobenzene with alkaline ascorbic acid: Kinetics and pathways

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chenju, E-mail: cliang@nchu.edu.tw [Department of Environmental Engineering, National Chung Hsing University 250, Kuo-kuang Road, Taichung 402, Taiwan (China); Lin, Ya-Ting [Department of Environmental Engineering, Chung Yuan Christian University, 200 Chung Pei Road, Chung Li District, Taoyuan City 320, Taiwan (China); Shiu, Jia-Wei [Department of Environmental Engineering, National Chung Hsing University 250, Kuo-kuang Road, Taichung 402, Taiwan (China)

    2016-01-25

    Highlights: • Alkaline ascorbic acid (a.k.a. vitamin C) is capable of reductively degrading NB. • The pH above the pK{sub a2} of ascorbic acid increases reductive electron transfer to NB. • The rate equation for the reactions between NB and AA is determined. • NSB, AZOXY, and AZO are identified as intermediates and aniline as a final product. • Alkaline pH is essential for AA remediation of NB contaminated soils. - Abstract: Alkaline ascorbic acid (AA) exhibits the potential to reductively degrade nitrobenzene (NB), which is the simplest of the nitroaromatic compounds. The nitro group (NO{sub 2}{sup −}) of NB has a +III oxidation state of the N atom and tends to gain electrons. The effect of alkaline pH ranging from 9 to 13 was initially assessed and the results demonstrated that the solution pH, when approaching or above the pK{sub a2} of AA (11.79), would increase reductive electron transfer to NB. The rate equation for the reactions between NB and AA at pH 12 can be described as r = ((0.89 ± 0.11) × 10{sup −4} mM{sup 1−(a} {sup +} {sup b)} h{sup −1}) × [NB]{sup a} {sup =} {sup 1.35} {sup ±} {sup 0.10}[AA]{sup b} {sup =} {sup 0.89} {sup ±} {sup 0.01}. The GC/MS analytical method identified nitrosobenzene, azoxybenzene, and azobenzene as NB reduction intermediates, and aniline (AN) as a final product. These experimental results indicate that the alkaline AA reduction of NB to AN mainly proceeds via the direct route, consisting of a series of two-electron or four-electron transfers, and the condensation reaction plays a minor route. Preliminary evaluation of the remediation of spiked NB contaminated soils revealed that maintenance of alkaline pH and a higher water to soil ratio are essential for a successful alkaline AA application.

  16. Mixed Causal-Noncausal Autoregressions with Strictly Exogenous Regressors

    NARCIS (Netherlands)

    Hecq, Alain; Issler, J.V.; Telg, Sean

    2017-01-01

    The mixed autoregressive causal-noncausal model (MAR) has been proposed to estimate economic relationships involving explosive roots in their autoregressive part, as they have stationary forward solutions. In previous work, possible exogenous variables in economic relationships are substituted into

  17. The use of exogenous microbial species to enhance the ...

    African Journals Online (AJOL)

    film bioreactor with exogenous bacterial and diatoma species would increase the removal of chemical oxygen demand, nitrogenous compounds and suspended solids from a real-time coal gasification wastewater to meet environmental ...

  18. Effect of exogenously added rhamnolipids on citric acid production ...

    African Journals Online (AJOL)

    Effect of exogenously added rhamnolipids on citric acid production yield. Wojciech Białas, Roman Marecik, Alicja Szulc, Łukasz Ławniczak, Łukasz Chrzanowski, Filip Ciesielczyk, Teofil Jesionowski, Andreas Aurich ...

  19. Isolating Exogenous and Endogenous Modes of Temporal Attention

    Science.gov (United States)

    Lawrence, Michael A.; Klein, Raymond M.

    2013-01-01

    The differential allocation of information processing resources over time, here termed "temporal attention," may be achieved by relatively automatic "exogenous" or controlled "endogenous" mechanisms. Over 100 years of research has confounded these theoretically distinct dimensions of temporal attention. The current…

  20. Radioprotective effect of exogenic hypoxia in fractionated irradiation

    International Nuclear Information System (INIS)

    Kazymbetov, P.; Yarmonenko, S.P.; Vajnson, A.A.

    1988-01-01

    During the experiments with mice it is established, that exogenic hypoxia protective effect (8%O 2 ), evaluated according to survival rate, decreases at the change from single to fractionated irradiation. Dose change factor (DCF) is equal to 1.55 and 1.22-1.31, respectively. Skin protection using exogenic hypoxia at the local fractionated irradiation is expressed more, than at the fractionated one. DCF is equal to 1.56 and 1.28, respectively. Exogenic hypoxia protection effect in the tumor is expressed rather weakly. DCF at single and fractionated irradiation constitutes 1.03 and 1.07-1.13, respectively. Due to skin preferential protection the therapeutic gain factor at irradiation under the exogenic hypoxia conditions constitutes 1.24 and 1.38-1.46, respectively, at single and fractionated irradiation

  1. Minnesota urban partnership agreement national evaluation : exogenous factors test plan.

    Science.gov (United States)

    2009-11-17

    This report presents the exogenous factors test plan for the national evaluation of the Minnesota Urban Partnership Agreement (UPA) under the United States Department of Transportation (U.S. DOT) UPA Program. The Minnesota UPA projects focus on reduc...

  2. Effects of exogenous polyamines and inhibitors of polyamine ...

    African Journals Online (AJOL)

    guanylhydrazone) (MGBG) and dicyclohexylamine (DCHA) or three exogenous polyamines (putrescine, spermidine and spermine) were added into a modified HLM-1 maturation medium inoculated with embryogenic tissues. Medium responses were ...

  3. Is subclinical hypothyroidism increasing exogen obesity in children?

    Directory of Open Access Journals (Sweden)

    Ceyda Tuna Kirsaclioglu

    2015-03-01

    Conclusion:.Thyrotropin releasing hormone stimulation test may be helpful to determine subclinical hypothyroidism in exogen obese children, if basal TSH levels were elevated. [J Contemp Med 2015; 5(1.000: 1-7

  4. Spatial orienting around the fovea: exogenous and endogenous cueing effects.

    Science.gov (United States)

    Yang, Taoxi; Zhang, Jiyuan; Bao, Yan

    2015-09-01

    The effect of covert attention in perifoveal and peripheral locations has been studied extensively. However, it is less clear whether attention operates similarly in the foveal area itself. The present study aims to investigate whether the attentional orienting elicited by an exogenous or endogenous cue can operate within the foveal area and whether attentional orienting operates similarly between foveal and perifoveal regions. By manipulating exogenous orienting in Experiment 1 and endogenous orienting in Experiment 2, we observed both forms of cueing in the foveal area. Specifically, we observed a larger exogenous cue-induced inhibitory effect (i.e., inhibition of return effect) and a similar endogenous cue-elicited facilitatory effect for the perifoveal relative to the foveal targets. We conclude that exogenous and endogenous orienting subject to two independent attentional systems with distinct modulation patterns in the foveal area.

  5. Exogenous application of plant growth regulators increased the total ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... the exogenous application of flavonoids reports plant growth regulation ... method used for extraction and quantification of endogenous gibberellins was ... 365 nm) while separation was done on a C18 reverse-phase HPLC.

  6. Effect of ascorbate ions in DTPA treatment after contamination by mixed plutonium dioxide-sodium burning products

    International Nuclear Information System (INIS)

    Metivier, H.; Masse, R.; Nolibe, D.; Nenot, J.C.; Lafuma, J.

    1977-01-01

    Plutonium toxicity problems arising from the use of molten sodium cooled fast breeder reactors involving the accidental mixing and ignition of sodium contaminated by plutonium dioxide have been investigated. The possibility of using the strong reducing agent, ascorbate ion, in order to reduce Pu VI to a chemical form more complexable by DTPA, has been tested using male and female rats. Urine, feces, liver and skeletal measurements of 239 Pu daughter products were carried out. It was shown that the transportable fraction was not significantly modified by the associate ascorbate-DTPA treatment. However the skeletal burden which represents 2.2% with DTPA, reached only 1.6% with ascorbate association and 0.3% with preventive ascorbate injections. Whatever the DTPA ascorbate treatment, the liver burden was not modified significantly. Difference observable only with preventive ascorbate treatment cancels out ascorbate association in order to greatly increase DTPA therapy efficiency, but seems to indicate that the Pu-proteins associations in blood is reduced more easily by ascorbate than association of Pu with local proteins. Ascorbate reduction can also be observed in urinary elimination in that preventive ascorbate, followed by DTPA-ascorbate, leads to a quicker urinary elimination than DTPA or DTPA plus ascorbate post treatment. (U.K.)

  7. Purification of the Membrane Compartment for Endoplasmic Reticulum-associated Degradation of Exogenous Antigens in Cross-presentation.

    Science.gov (United States)

    Imai, Jun; Otani, Mayu; Sakai, Takahiro; Hatta, Shinichi

    2017-08-21

    Dendritic cells (DCs) are highly capable of processing and presenting internalized exogenous antigens upon major histocompatibility class (MHC) I molecules also known as cross-presentation (CP). CP plays an important role not only in the stimulation of naïve CD8 + T cells and memory CD8 + T cells for infectious and tumor immunity but also in the inactivation of self-acting naïve T cells by T cell anergy or T cell deletion. Although the critical molecular mechanism of CP remains to be elucidated, accumulating evidence indicates that exogenous antigens are processed through endoplasmic reticulum-associated degradation (ERAD) after export from non-classical endocytic compartments. Until recently, characterizations of these endocytic compartments were limited because there were no specific molecular markers other than exogenous antigens. The method described here is a new vesicle isolation protocol, which allows for the purification of these endocytic compartments. Using this purified microsome, we reconstituted the ERAD-like transport, ubiquitination, and processing of the exogenous antigen in vitro, suggesting that the ubiquitin-proteasome system processed the exogenous antigen after export from this cellular compartment. This protocol can be further applied to other cell types to clarify the molecular mechanism of CP.

  8. Induced effect of irradiated exogenous DNA on wheat

    International Nuclear Information System (INIS)

    Li Zhongjie; Sun Guangzu; Wang Guangjin

    1996-01-01

    Irradiated exogenous DNA introduced into wheat can give rise to break of DNA-chain and damage of part of alkali radicals. Introducing exogenous DNA irradiated by γ rays could increase Do fructification rate and decrease seed size and plumpness. These tendencies became obvious with dose increase. In comparison with control DNA, introducing DNA irradiated could raise evidently mutagenic effect of pollen tube pathway technique

  9. Exogenous (automatic) attention to emotional stimuli: a review

    OpenAIRE

    Carretié, Luis

    2014-01-01

    Current knowledge on the architecture of exogenous attention (also called automatic, bottom-up, or stimulus-driven attention, among other terms) has been mainly obtained from studies employing neutral, anodyne stimuli. Since, from an evolutionary perspective, exogenous attention can be understood as an adaptive tool for rapidly detecting salient events, reorienting processing resources to them, and enhancing processing mechanisms, emotional events (which are, by definition, salient for the in...

  10. Interaction between endogenous and exogenous orienting in crossmodal attention.

    Science.gov (United States)

    Chen, Xiaoxi; Chen, Qi; Gao, Dingguo; Yue, Zhenzhu

    2012-08-01

    Using a cue-target paradigm, we investigated the interaction between endogenous and exogenous orienting in cross-modal attention. A peripheral (exogenous) cue was presented after a central (endogenous) cue with a variable time interval. The endogenous and exogenous cues were presented in one sensory modality (auditory in Experiment 1 and visual in Experiment 2) whereas the target was presented in another modality. Both experiments showed a significant endogenous cuing effect (longer reaction times in the invalid condition than in the valid condition). However, exogenous cuing produced a facilitatory effect in both experiments in response to the target when endogenous cuing was valid, but it elicited a facilitatory effect in Experiment 1 and an inhibitory effect in Experiment 2 when endogenous cuing was invalid. These findings indicate that endogenous and exogenous cuing can co-operate in orienting attention to the crossmodal target. Moreover, the interaction between endogenous and exogenous orienting of attention is modulated by the modality between the cue and the target. © 2012 The Authors. Scandinavian Journal of Psychology © 2012 The Scandinavian Psychological Associations.

  11. P-wave dispersion in endogenous and exogenous subclinical hyperthyroidism.

    Science.gov (United States)

    Gen, R; Akbay, E; Camsari, A; Ozcan, T

    2010-02-01

    The aim of this study was to measure maximum P wave duration (Pmax) and P wave dispersion (PWD), which can be indicators for the risk of paroxysmal atrial fibrillation when increased, and to reveal their relationship with thyroid hormone levels in patients with endogenous and exogenous subclinical hyperthyroidism. Seventy-one patients with sublinical thyrotoxicosis (34 endogenous, 37 exogenous) and 69 healthy individuals were enrolled in the study. Pmax and minimum P wave duration (Pmin) on electrocardiogram recordings were measured and PWD was calculated as Pmax-Pmin. Pmax (pendogenous subclinical hyperthyroidism compared with the control group. Pmax (pexogenous subclinical thyrotoxicosis compared with the control group. Pmax (p=0.710) and PWD (p=0.127) were not significantly different in patients with endogenous subclinical hyperthyroidism compared with exogenous subclinical hyperthyroid patients. Pmax and PWD negatively associated with TSH in endogenous and exogenous subclinical hyperthyroidism. In the present study, we observed that Pmax and PWD were longer in patients with endogenous and exogenous subclinical hyperthyroidism. Lack of a difference in Pmax and PWD between patients with endogenous and exogenous subclinical hyperthyroidism seems to support the idea that hormone levels rather than the etiology of thyrotoxicosis affect the heart.

  12. A flexible micro biofuel cell utilizing hydrogel containing ascorbic acid

    Science.gov (United States)

    Goto, Hideaki; Fukushi, Yudai; Nishioka, Yasushiro

    2014-11-01

    This paper reports on a biofuel cell with a dimension of 13×24 mm2 fabricated on a flexible polyimide substrate. I its porous carbon-coated platinum (Pt) electrodes of 3 mm in width and 10 mm in length were fabricated using photolithography and screen printing techniques. Porous carbon was deposited by screen printing of carbon black ink on the Pt electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the electrode surfaces. It utilizes a solidified ascorbic acid (AA) aqueous solution in an agarose hydrogel to increase the portability. The maximum power and power density for the biofuel cell with the fuel unit containing 100 mM AA were 0.063 μW and 0.21 μW/cm2 at 0.019 V, respectively.

  13. A flexible micro biofuel cell utilizing hydrogel containing ascorbic acid

    International Nuclear Information System (INIS)

    Goto, Hideaki; Fukushi, Yudai; Nishioka, Yasushiro

    2014-01-01

    This paper reports on a biofuel cell with a dimension of 13×24 mm 2 fabricated on a flexible polyimide substrate. I its porous carbon-coated platinum (Pt) electrodes of 3 mm in width and 10 mm in length were fabricated using photolithography and screen printing techniques. Porous carbon was deposited by screen printing of carbon black ink on the Pt electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the electrode surfaces. It utilizes a solidified ascorbic acid (AA) aqueous solution in an agarose hydrogel to increase the portability. The maximum power and power density for the biofuel cell with the fuel unit containing 100 mM AA were 0.063 μW and 0.21 μW/cm 2 at 0.019 V, respectively

  14. In situ production of silver nanoparticles for high sensitive detection of ascorbic acid via inner filter effect

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei, B., E-mail: rezaeimeister@gmail.com; Shahshahanipour, M.; Ensafi, Ali A.

    2017-02-01

    In the present research, a sensitive biosensing method was proposed for the detection of trace amounts of ascorbic acid (AA). Herein, colloidal silver nanoparticles (SNPs) were successfully in-situ produced by chemical reduction of silver ion in the presence of AA, as a reducing agent. The one-pot in-situ produced silver nanoparticles were characterized by UV–vis, dynamic light scattering (DLS), zeta potential and transmission electron microscopic (TEM). SNPs act as a strong fluorescence quencher for the CdTe quantum dots via an inner filter effect (IFE). Since the absorption band of SNPs entirely covered both emission and excitation bands of QDs. Therefore, the decreasing in the fluorescence signal depends on the AA concentration in the linear range of 0.2–88.0 ng mL{sup −1} and with a detection limit of 0.02 ng mL{sup −1}. Relative standard deviations of 2.3% and 2.8% (n = 5) were achieved for the determination of 1.8 and 8.8 ng mL{sup −1} AA, respectively. This novel QDs nanosensor based on IFE could provide noticeable advantages of simplicity, convenience, cost-effectiveness, and sensitivity. This method was successfully applied for the detection of ascorbic acid in human real samples serums. - Highlights: • A sensitive and simple method has been developed for detection of ascorbic acid. • Silver nanoparticles as a strong quencher were prepared via the one-step reduction. • Its absorption band covered both emission and excitation bands of CdTe QDs. • So, the fluorescence of CdTe QDs quenching due to Inner filter effect.

  15. Exogenous melatonin suppresses dark-induced leaf senescence by activating the superoxide dismutase-catalase antioxidant pathway and down-regulating chlorophyll degradation in excised leaves of perennial ryegrass (Lolium perenne L.

    Directory of Open Access Journals (Sweden)

    Jing Zhang

    2016-10-01

    Full Text Available Leaf senescence is a typical symptom in plants exposed to dark and may be regulated by plant growth regulators. The objective of this study was to determine whether exogenous application of melatonin (N-acetyl-5-methoxytryptamine suppresses dark-induced leaf senescence and the effects of melatonin on reactive oxygen species (ROS scavenging system and chlorophyll degradation pathway in perennial grass species. Mature perennial ryegrass (Lolium perenne L. cv. ‘Pinnacle’ leaves were excised and incubated in 3 mM 2-(N-morpholino ethanesulfonic buffer (pH 5.8 supplemented with melatonin or water (control and exposed to dark treatment for 8 d. Leaves treated with melatonin maintained significantly higher endogenous melatonin level, chlorophyll content, photochemical efficiency, and cell membrane stability expressed by lower electrolyte leakage and malondialdehyde (MDA content compared to the control. Exogenous melatonin treatment also reduced the transcript level of chlorophyll degradation-associated genes and senescence marker genes (LpSAG12.1, Lph36, and Lpl69 during the dark treatment. The endogenous O2- production rate and H2O2 content were significantly lower in these excised leaves treated with melatonin compared to the water control. Exogenous melatonin treatment caused increases in enzymatic activity and transcript levels of superoxide dismutase and catalase but had no significant effects on ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and monohydroascorbate reductase. The content of non-enzymatic antioxidants, such as ascorbate and dehydroascorbate, were decreased by melatonin treatment, while the content of glutathione and oxidized glutathione was not affected by melatonin. These results suggest that the suppression of dark-induced leaf senescence by exogenous melatonin may be associated with its roles in regulating ROS scavenging through activating the superoxide dismutase-catalase enzymatic antioxidant

  16. Distribution of ascorbate-2-sulfate and distribution, half-life and turnover rates of [1-14C]ascorbic acid in rainbow trout

    International Nuclear Information System (INIS)

    Tucker, B.W.; Halver, J.E.

    1984-01-01

    Rainbow trout (250 g) were maintained at 15 degrees C for 3 months on a low ascorbic acid diet, given [1- 14 C]ascorbic acid by gavage, then fed the NAS/NRC requirement 12 times per week. Total urine, fecal water and branchial water were collected daily from five fish placed in metabolism chambers for four successive 5-day periods. Tissue samples were analyzed for 14 C, ascorbic acid (C1) and ascorbate-2-sulfate (C2). Excretion analysis indicated t1/2 . 42 days. After 20 days, the feeding schedule was changed to 3 times per week. Fish fed 14 C were sampled after 1, 2, 3 and 4 months. The half-life in each organ except brain was inversely proportional to the dietary level of ascorbate. Concentrations of C1 and C2 in the various tissues reflected dietary intake of vitamin C. Total C (CT . C1 + C2) levels were maintained in the liver even with the low vitamin C diet. Estimates of body pool for C1 are 27-29 mg/kg. At the higher ascorbate intake CT was 92-114 mg/kg, but decreased by 34% at the lower feeding rate to 51-62 mg/kg. Data indicate that there are two or more body pools that include a store of C2, which is readily interconverted in metabolizing tissues to and from C1. Since air and water stable C2 is antiscorbutic for fish, it is the preferred form of ascorbate for fish feeds

  17. Exogenous Calcium Enhances the Photosystem II Photochemistry Response in Salt Stressed Tall Fescue.

    Science.gov (United States)

    Wang, Guangyang; Bi, Aoyue; Amombo, Erick; Li, Huiying; Zhang, Liang; Cheng, Cheng; Hu, Tao; Fu, Jinmin

    2017-01-01

    Calcium enhances turfgrass response to salt stress. However, little is known about PSII photochemical changes when exogenous calcium was applied in salinity-stressed turfgrass. Here, we probe into the rearrangements of PSII electron transport and endogenous ion accumulation in tall fescue ( Festuca arundinacea Schreber) treated with exogenous calcium under salt stress. Three-month-old seedlings of genotype "TF133" were subjected to the control (CK), salinity (S), salinity + calcium nitrate (SC), and salinity + ethylene glycol tetraacetic acid (SE). Calcium nitrate and ethylene glycol tetraacetic acid was used as exogenous calcium donor and calcium chelating agent respectively. At the end of a 5-day duration treatment, samples in SC regime had better photochemistry performance on several parameters than salinity only. Such as the Area (equal to the plastoquinone pool size), N (number of [Formula: see text] redox turnovers until F m is reached), ψE 0 , or δRo (Efficiencdy/probability with which a PSII trapped electron is transferred from Q A to Q B or PSI acceptors), ABS/RC (Absorbed photon flux per RC). All the above suggested that calcium enhanced the electron transfer of PSII (especially beyond [Formula: see text]) and prevented reaction centers from inactivation in salt-stressed tall fescue. Furthermore, both grass shoot and root tissues generally accumulated more C, N, Ca 2+ , and K + in the SC regime than S regime. Interrelated analysis indicated that ψE 0 , δRo, ABS/RC, C, and N content in shoots was highly correlated to each other and significantly positively related to Ca 2+ and K + content in roots. Besides, high salt increased ATP6E and CAMK2 transcription level in shoot at 1 and 5 day, respectively while exogenous calcium relieved it. In root, CAMK2 level was reduced by Salinity at 5 day and exogenous calcium recovered it. These observations involved in electron transport capacity and ion accumulation assist in understanding better the protective role

  18. Exogenous Calcium Enhances the Photosystem II Photochemistry Response in Salt Stressed Tall Fescue

    Directory of Open Access Journals (Sweden)

    Guangyang Wang

    2017-11-01

    Full Text Available Calcium enhances turfgrass response to salt stress. However, little is known about PSII photochemical changes when exogenous calcium was applied in salinity-stressed turfgrass. Here, we probe into the rearrangements of PSII electron transport and endogenous ion accumulation in tall fescue (Festuca arundinacea Schreber treated with exogenous calcium under salt stress. Three-month-old seedlings of genotype “TF133” were subjected to the control (CK, salinity (S, salinity + calcium nitrate (SC, and salinity + ethylene glycol tetraacetic acid (SE. Calcium nitrate and ethylene glycol tetraacetic acid was used as exogenous calcium donor and calcium chelating agent respectively. At the end of a 5-day duration treatment, samples in SC regime had better photochemistry performance on several parameters than salinity only. Such as the Area (equal to the plastoquinone pool size, N (number of QA- redox turnovers until Fm is reached, ψE0, or δRo (Efficiencdy/probability with which a PSII trapped electron is transferred from QA to QB or PSI acceptors, ABS/RC (Absorbed photon flux per RC. All the above suggested that calcium enhanced the electron transfer of PSII (especially beyond QA- and prevented reaction centers from inactivation in salt-stressed tall fescue. Furthermore, both grass shoot and root tissues generally accumulated more C, N, Ca2+, and K+ in the SC regime than S regime. Interrelated analysis indicated that ψE0, δRo, ABS/RC, C, and N content in shoots was highly correlated to each other and significantly positively related to Ca2+ and K+ content in roots. Besides, high salt increased ATP6E and CAMK2 transcription level in shoot at 1 and 5 day, respectively while exogenous calcium relieved it. In root, CAMK2 level was reduced by Salinity at 5 day and exogenous calcium recovered it. These observations involved in electron transport capacity and ion accumulation assist in understanding better the protective role of exogenous calcium in tall

  19. Effects of GA3, BA, Thiamine and Ascorbic Acid on Some Morphological and Biochemical Characteristics of Periwinkle (Catharanthus roseus L.

    Directory of Open Access Journals (Sweden)

    F. Baniasadi

    2016-07-01

    . All growth promoter substances increased flower diameter. Combined application of BAwith gibberellic acid had more influence on this parameter than other treatments, and increase flower diameter about 25%. Ascorbic acid plays an important role in cell division, plasma membrane, proton pumps and enlargement cell. According to the theory of acidic growth, ascorbic acid weakens cell wall and increases cell enlargement. Among the applied treatments combination of banzyladenine, thiamine and ascorbic acid increased the number of lateral branches to 100%. Results showed that GA in all concentrations and combinations used in this experiment increased lateral branches length. Several reports in plants such as croton, hibiscus and pot marigold indicated that BA can increase the number of branches per plant. Therefore, BA is used to enhance branching and to reduce the total height of the plants. The highest fresh and dry weight were observed in plants treated with the combinations of BA, thiamine and ascorbic acid. Thiamine increased chlorophyll a content more than other substances. There was no significant difference between thiamine or thiamine combined with ascorbic acid treatment on chlorophyll b content. Thiamine in combinations with all the other treatments significantly improved carotenoids content compared to control. Chlorophyll plays a key role in plants for the absorption and utilization of light energy which used in photosynthesis. Therefore, effects of PGRs on chlorophyll biosynthesis or degradation influence directly on photosynthesis. Thiamine was reported that in some plants assist resynthesize of chlorophyll in plant without chlorophyll and increased growth and yield eventually. All the treatments significantly increased reducing sugar. Although all of the substances improved the amount of reducing sugar, the role of thiamine was more dramatic compared to other treatments. The greatest amount of reducing sugar 85.3 mg. g-1 fresh weight was observed in the

  20. Effects of ascorbic acid and antioxidants on color, lipid oxidation and volatiles of irradiated ground beef

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, D.U. E-mail: duahn@iastate.edu; Nam, K.C

    2004-10-01

    Beef loins with 3 different aging times after slaughter were ground, added with none, 0.1% ascorbic acid, 0.01% sesamol+0.01% {alpha}-tocopherol, or 0.1% ascorbic acid+0.01% sesamol+0.01% tocopherol. The meats were packaged in oxygen-permeable bags, irradiated at 2.5 kGy, and color, oxidation-reduction potential (ORP), lipid oxidation and volatile profiles were determined. Irradiation decreased the redness of ground beef, and visible color of beef changed from a bright red to a green/brown depending on the age of meat. Addition of ascorbic acid prevented color changes in irradiated beef, and the effect of ascorbic acid became greater as the age of meat or storage time after irradiation increased. The ground beef added with ascorbic acid had lower ORP than control, and the low ORP of meat helped maintaining the heme pigments in reduced form. During aerobic storage, S-volatiles disappeared while volatile aldehydes significantly increased in irradiated beef. Addition of ascorbic acid at 0.1% or sesamol+{alpha}-tocopherol at each 0.01% level to ground beef prior to irradiation were effective in reducing lipid oxidation and S-volatiles. As storage time increased, however, the antioxidant effect of sesamol+tocopherol in irradiated ground beef was superior to that of ascorbic acid.

  1. Effects of ascorbic acid and antioxidants on color, lipid oxidation and volatiles of irradiated ground beef

    International Nuclear Information System (INIS)

    Ahn, D.U.; Nam, K.C.

    2004-01-01

    Beef loins with 3 different aging times after slaughter were ground, added with none, 0.1% ascorbic acid, 0.01% sesamol+0.01% α-tocopherol, or 0.1% ascorbic acid+0.01% sesamol+0.01% tocopherol. The meats were packaged in oxygen-permeable bags, irradiated at 2.5 kGy, and color, oxidation-reduction potential (ORP), lipid oxidation and volatile profiles were determined. Irradiation decreased the redness of ground beef, and visible color of beef changed from a bright red to a green/brown depending on the age of meat. Addition of ascorbic acid prevented color changes in irradiated beef, and the effect of ascorbic acid became greater as the age of meat or storage time after irradiation increased. The ground beef added with ascorbic acid had lower ORP than control, and the low ORP of meat helped maintaining the heme pigments in reduced form. During aerobic storage, S-volatiles disappeared while volatile aldehydes significantly increased in irradiated beef. Addition of ascorbic acid at 0.1% or sesamol+α-tocopherol at each 0.01% level to ground beef prior to irradiation were effective in reducing lipid oxidation and S-volatiles. As storage time increased, however, the antioxidant effect of sesamol+tocopherol in irradiated ground beef was superior to that of ascorbic acid

  2. A metabolic switch in brain: glucose and lactate metabolism modulation by ascorbic acid.

    Science.gov (United States)

    Castro, Maite A; Beltrán, Felipe A; Brauchi, Sebastián; Concha, Ilona I

    2009-07-01

    In this review, we discuss a novel function of ascorbic acid in brain energetics. It has been proposed that during glutamatergic synaptic activity neurons preferably consume lactate released from glia. The key to this energetic coupling is the metabolic activation that occurs in astrocytes by glutamate and an increase in extracellular [K(+)]. Neurons are cells well equipped to consume glucose because they express glucose transporters and glycolytic and tricarboxylic acid cycle enzymes. Moreover, neuronal cells express monocarboxylate transporters and lactate dehydrogenase isoenzyme 1, which is inhibited by pyruvate. As glycolysis produces an increase in pyruvate concentration and a decrease in NAD(+)/NADH, lactate and glucose consumption are not viable at the same time. In this context, we discuss ascorbic acid participation as a metabolic switch modulating neuronal metabolism between rest and activation periods. Ascorbic acid is highly concentrated in CNS. Glutamate stimulates ascorbic acid release from astrocytes. Ascorbic acid entry into neurons and within the cell can inhibit glucose consumption and stimulate lactate transport. For this switch to occur, an ascorbic acid flow is necessary between astrocytes and neurons, which is driven by neural activity and is part of vitamin C recycling. Here, we review the role of glucose and lactate as metabolic substrates and the modulation of neuronal metabolism by ascorbic acid.

  3. Role of ascorbic acid in stratum corneum lipid models exposed to UV irradiation.

    Science.gov (United States)

    Trommer, Hagen; Böttcher, Roif; Pöppl, Andreas; Hoentsch, Joachim; Wartewig, Siegfried; Neubert, Reinhard H H

    2002-07-01

    The effects of ascorbic acid on Stratum corneum lipid models following ultraviolet irradiation were studied adding iron ions as transition metal catalysts. Lipid peroxidation was quantified by the thiobarbituric acid assay. The qualitative changes were studied on a molecular level by mass spectrometry. To elucidate the nature of free radical involvement we carried out electron paramagnetic resonance studies. The influence of ascorbic acid on the concentration of hydroxyl radicals was examined using the spin trapping technique. Moreover, we checked the vitamin's ability to react with stable radicals. Ascorbic acid was found to have prooxidative effects in all lipid systems in a concentration dependent manner. The degradation products of ascorbic acid after its prooxidative action were detected. The concentration of the hydroxyl radicals in the Fenton assay was decreased by ascorbic acid. The quantification assay of 2,2-diphenyl-1-picrylhydrazyl hydrate showed reduced concentration levels of the stable radical caused by ascorbic acid. Considering human skin and its constant exposure to UV light and oxygen, an increased pool of iron ions in irradiated skin and the depletion of co-antioxidants, the administration of ascorbic acid in cosmetic formulations or in sunscreens could unfold adverse effects among the Stratum corneum lipids.

  4. High Dose Ascorbate Causes Both Genotoxic and Metabolic Stress in Glioma Cells

    Science.gov (United States)

    Castro, Maria Leticia; Carson, Georgia M.; McConnell, Melanie J.; Herst, Patries M.

    2017-01-01

    We have previously shown that exposure to high dose ascorbate causes double stranded breaks (DSBs) and a build-up in S-phase in glioblastoma (GBM) cell lines. Here we investigated whether or not this was due to genotoxic stress as well as metabolic stress generated by exposure to high dose ascorbate, radiation, ascorbate plus radiation and H2O2 in established and primary GBM cell lines. Genotoxic stress was measured as phosphorylation of the variant histone protein, H2AX, 8-oxo-7,8-dihydroguanine (8OH-dG) positive cells and cells with comet tails. Metabolic stress was measured as a decrease in NADH flux, mitochondrial membrane potential (by CMXRos), ATP levels (by ATP luminescence) and mitochondrial superoxide production (by mitoSOX). High dose ascorbate, ascorbate plus radiation, and H2O2 treatments induced both genotoxic and metabolic stress. Exposure to high dose ascorbate blocked DNA synthesis in both DNA damaged and undamaged cell of ascorbate sensitive GBM cell lines. H2O2 treatment blocked DNA synthesis in all cell lines with and without DNA damage. DNA synthesis arrest in cells with damaged DNA is likely due to both genotoxic and metabolic stress. However, arrest in DNA synthesis in cells with undamaged DNA is likely due to oxidative damage to components of the mitochondrial energy metabolism pathway. PMID:28737676

  5. Estimation of redox potentials of Fe(III)- gallic acid complexes at different pH by spectrophotometric titration with ascorbate

    International Nuclear Information System (INIS)

    Iqbal, M.; Tasneem, Z.; Kazmi, S.A.

    1993-01-01

    Fe(III) is strongly chelated by Gallic acid. This equilibrium as well as the kinetics of reduction of the complex is strongly pH dependent. The complex was prepared in acetate buffers of pH 4.6, 5.0 and 5.6 and in Tris buffer of pH 7.0.The complex was reduced by ascorbate. The reduced absorbance was taken to be a measure of reaction. Nernst equation was then applied to determine the standard redox potentials of the complex taking the literature values of the redox potentials of ascorbate at different pH. The values of redox potentials of complex were found to be 0.197 V at pH 4.6. 0.181 V at pH 5.0 1.132 V at pH 5.6 and 0.092 V at pH 7.0. (author)

  6. D-penicillamine-templated copper nanoparticles via ascorbic acid reduction as a mercury ion sensor.

    Science.gov (United States)

    Lin, Shu Min; Geng, Shuo; Li, Na; Li, Nian Bing; Luo, Hong Qun

    2016-05-01

    Mercury ion is one of the most hazardous metal pollutants that can cause deleterious effects on human health and the environment even at low concentrations. It is necessary to develop new mercury detection methods with high sensitivity, specificity and rapidity. In this study, a novel and green strategy for synthesizing D-penicillamine-capped copper nanoparticles (DPA-CuNPs) was successfully established by a chemical reduction method, in which D-penicillamine and ascorbic acid were used as stabilizing agent and reducing agent, respectively. The as-prepared DPA-CuNPs showed strong red fluorescence and had a large Stoke's shift (270nm). Scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, fluorescence spectroscopy, and ultraviolet-visible spectrophotometry were utilized to elucidate the possible fluorescence mechanism, which could be aggregation-induced emission effect. Based on the phenomenon that trace mercury ion can disperse the aggregated DPA-CuNPs, resulting in great fluorescence quench of the system, a sensitive and selective assay for mercury ion in aqueous solution with the DPA-CuNPs was developed. Under optimum conditions, this assay can be applied to the quantification of Hg(2+) in the 1.0-30μM concentration range and the detection limit (3σ/slope) is 32nM. The method was successfully applied to determine Hg(2+) in real water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Structural Requirements of Alkylglyceryl-l-Ascorbic Acid Derivatives for Melanogenesis Inhibitory Activity.

    Science.gov (United States)

    Taira, Norihisa; Katsuyama, Yushi; Yoshioka, Masato; Muraoka, Osamu; Morikawa, Toshio

    2018-04-10

    l-Ascorbic acid has multifunctional benefits on skin aesthetics, including inhibition of melanin production, and is widely used in cosmetics. It, however, has low stability and poor skin penetration. We hypothesize that alkylglyceryl-l-ascorbic acid derivatives, highly stable vitamin C-alkylglycerol conjugates, would have similar anti-melanogenic activity with better stability and penetration. We test 28 alkylglyceryl-l-ascorbic acid derivatives ( 1 - 28 ) on theophylline-stimulated B16 melanoma 4A5 cells to determine if they inhibit melanogenesis and establish any structure-function relationships. Although not the most potent inhibitors, 3- O -(2,3-dihydroxypropyl)-2- O -hexyl-l-ascorbic acid ( 6 , IC 50 = 81.4 µM) and 2- O -(2,3-dihydroxypropyl)-3- O -hexyl-l-ascorbic acid ( 20 , IC 50 = 117 µM) are deemed the best candidate derivatives based on their inhibitory activities and low toxicities. These derivatives are also found to be more stable than l-ascorbic acid and to have favorable characteristics for skin penetration. The following structural requirements for inhibitory activity of alkylglyceryl-l-ascorbic acid derivatives are also determined: (i) alkylation of glyceryl-l-ascorbic acid is essential for inhibitory activity; (ii) the 3- O -alkyl-derivatives ( 2 - 14 ) exhibit stronger inhibitory activity than the corresponding 2- O -alkyl-derivatives ( 16 - 28 ); and (iii) derivatives with longer alkyl chains have stronger inhibitory activities. Mechanistically, our studies suggest that l-ascorbic acid derivatives exert their effects by suppressing the mRNA expression of tyrosinase and tyrosine-related protein-1.

  8. Modelling and predicting electricity consumption in Spain using the stochastic Gamma diffusion process with exogenous factors

    International Nuclear Information System (INIS)

    Nafidi, A.; Gutiérrez, R.; Gutiérrez-Sánchez, R.; Ramos-Ábalos, E.; El Hachimi, S.

    2016-01-01

    The aim of this study is to model electric power consumption during a period of economic crisis, characterised by declining gross domestic product. A novel aspect of this study is its use of a Gamma-type diffusion process for short and medium-term forecasting – other techniques that have been used to describe such consumption patterns are not valid in this situation. In this study, we consider a new extension of the stochastic Gamma diffusion process by introducing time functions (exogenous factors) that affect its trend. This extension is defined in terms of Kolmogorov backward and forward equations. After obtaining the transition probability density function and the moments (specifically, the trend function), the inference on the process parameters is obtained by discrete sampling of the sample paths. Finally, this stochastic process is applied to model total net electricity consumption in Spain, when affected by the following set of exogenous factors: Gross Domestic Product (GDP), Gross Fixed Capital Formation (GFCF) and Final Domestic Consumption (FDC). - Highlights: • The aim is modelling and predicting electricity consumption in Spain. • We propose a Gamma-type diffusion process for short and medium-term forecasting. • We compared the fit using diffusion processes with different exogenous factors.

  9. Exogenous reinfection of tuberculosis in a low-burden area.

    Science.gov (United States)

    Schiroli, Consuelo; Carugati, Manuela; Zanini, Fabio; Bandera, Alessandra; Di Nardo Stuppino, Silvia; Monge, Elisa; Morosi, Manuela; Gori, Andrea; Matteelli, Alberto; Codecasa, Luigi; Franzetti, Fabio

    2015-12-01

    Recurrence of tuberculosis (TB) can be the consequence of relapse or exogenous reinfection. The study aimed to assess the factors associated with exogenous TB reinfection. Prospective cohort study based on the TB database, maintained at the Division of Infectious Diseases, Luigi Sacco Hospital (Milan, Italy). Time period: 1995-2010. (1) ≥2 episodes of culture-confirmed TB; (2) cure of the first episode of TB; (3) availability of one Mycobacterium tuberculosis isolate for each episode. Genotyping of the M. tuberculosis strains to differentiate relapse and exogenous reinfection. Logistic regression analysis was used to assess the influence of risk factors on exogenous reinfections. Of the 4682 patients with TB, 83 were included. Of these, exogenous reinfection was diagnosed in 19 (23 %). It was independently associated with absence of multidrug resistance at the first episode [0, 10 (0.01-0.95), p = 0.045] and with prolonged interval between the first TB episode and its recurrence [7.38 (1.92-28.32) p = 0.004]. However, TB relapses occurred until 4 years after the first episode. The risk associated with being foreign born, extrapulmonary site of TB, and HIV infection was not statistically significant. In the relapse and re-infection cohort, one-third of the patients showed a worsened drug resistance profile during the recurrent TB episode. Exogenous TB reinfections have been documented in low endemic areas, such as Italy. A causal association with HIV infection could not be confirmed. Relapses and exogenous reinfections shared an augmented risk of multidrug resistance development, frequently requiring the use of second-line anti-TB regimens.

  10. Redox regulation of peroxiredoxin and proteinases by ascorbate and thiols during pea root nodule senescence.

    Science.gov (United States)

    Groten, Karin; Dutilleul, Christelle; van Heerden, Philippus D R; Vanacker, Hélène; Bernard, Stéphanie; Finkemeier, Iris; Dietz, Karl-Josef; Foyer, Christine H

    2006-02-20

    Redox factors contributing to nodule senescence were studied in pea. The abundance of the nodule cytosolic peroxiredoxin but not the mitochondrial peroxiredoxin protein was modulated by ascorbate. In contrast to redox-active antioxidants such as ascorbate and cytosolic peroxiredoxin that decreased during nodule development, maximal extractable nodule proteinase activity increased progressively as the nodules aged. Cathepsin-like activities were constant throughout development but serine and cysteine proteinase activities increased during senescence. Senescence-induced cysteine proteinase activity was inhibited by cysteine, dithiotreitol, or E-64. Senescence-dependent decreases in redox-active factors, particularly ascorbate and peroxiredoxin favour decreased redox-mediated inactivation of cysteine proteinases.

  11. Effect of residual ascorbate on determination of nitrite in commercial cured meat products.

    Science.gov (United States)

    Fox, J B; Doerr, R C; Gates, R

    1984-01-01

    Residual ascorbate in cured meat slurries results in different amounts of pigment being produced from different Griess reagent combinations. The phenomenon was used to study residual ascorbate in commercial cured meat products which had a variety of textures, acidities, moisture and meat content, fat, homogeneity, initial nitrite, and processing conditions. Diluting and heating the samples according to the AOAC procedure did not completely eliminate the ascorbate interference, but making the sample alkaline did. Determining nitrite separately in supernate and precipitate from the first dilution showed the effect of heating to be the elimination of interferences and solubilization or extraction of nitrite from the precipitate.

  12. Intramolecular electron transfer in ascorbate oxidase is enhanced in the presence of oxygen

    DEFF Research Database (Denmark)

    Farver, O; Wherland, S; Pecht, I

    1994-01-01

    Intramolecular electron transfer from the type 1 copper center to the type 3 copper(II) pair is induced in the multi-copper enzyme, ascorbate oxidase, following pulse radiolytic reduction of the type 1 Cu(II) ion. In the presence of a slight excess of dioxygen over ascorbate oxidase, interaction...... between the trinuclear copper center and O2 is observed even with singly reduced ascorbate oxidase molecules. Under these conditions, the rate constant for intramolecular electron transfer from type 1 Cu(I) to type 3 Cu(II) increases 5-fold to 1100 +/- 300 s-1 (20 degrees C, pH 5.8) as compared...

  13. Metabolic Conversion of l-Ascorbic Acid to Oxalic Acid in Oxalate-accumulating Plants 1

    Science.gov (United States)

    Yang, Joan C.; Loewus, Frank A.

    1975-01-01

    l-Ascorbic acid-1-14C and its oxidation product, dehydro-l-ascorbic acid, produced labeled oxalic acid in oxalate-accumulating plants such as spinach seedlings (Spinacia oleracea) and the detached leaves of woodsorrel (Oxalis stricta and O. oregana), shamrock (Oxalis adenopylla), and begonia (Begonia evansiana). In O. oregana, conversion occurred equally well in the presence or absence of light. This relationship between l-ascorbic acid metabolism and oxalic acid formation must be given careful consideration in attempts to explain oxalic accumulation in plants. PMID:16659288

  14. Salivary ascorbic acid levels in betel quid chewers: A biochemical study

    OpenAIRE

    Shetty, Shishir R.; Babu, Subhas; Kumari, Suchetha; Prasad, Rajendra; Bhat, Supriya; Fazil, K. A.

    2013-01-01

    Background: Quid chewing practice has been a part of our tradition since centuries with little known evidence of oral cancer. However, recent trends show a rise in occurrence of oral cancer often associated with tobacco and arecanut usage. Ascorbic acid is an important salivary antioxidant. Betel leaf which is used in quid is known to contain ascorbic acid. Aim: The aim of our study was to assess the salivary levels of ascorbic acid in traditional quid chewers so as to determine whether the b...

  15. The effects of ascorbic acid on diphtheria toxin and intoxicated hela cells

    International Nuclear Information System (INIS)

    Clark, C.E.; Smith, T.J.

    1976-01-01

    Ascorbic acid (vitamin C) prevented diphtheria toxin from inhibiting the incorporation of [U- 14 C]-alanine into trichloroacetic acid precipitable material in HeLa cells. Ascorbic acid did not exhibit an effect on the adenosine diphosphate-ribosylation of amino acyl transferase 2 nor did it separate fragment A from fragment B in ''nicked'' toxin. A non-specific reducing agent, para-methylaminophenol sulfate, exhibited an effect of HeLa cells very similar to the results of ascorbic acid. Citric acid, a tricarboxylic acid, had no effect on HeLa cells. (auth.)

  16. Indirect potentiometric titration of ascorbic acid in pharmaceutical preparations using copper based mercury film electrode.

    Science.gov (United States)

    Abdul Kamal Nazer, Meeran Mohideen; Hameed, Abdul Rahman Shahul; Riyazuddin, Patel

    2004-01-01

    A simple and rapid potentiometric method for the estimation of ascorbic acid in pharmaceutical dosage forms has been developed. The method is based on treating ascorbic acid with iodine and titration of the iodide produced equivalent to ascorbic acid with silver nitrate using Copper Based Mercury Film Electrode (CBMFE) as an indicator electrode. Interference study was carried to check possible interference of usual excipients and other vitamins. The precision and accuracy of the method was assessed by the application of lack-of-fit test and other statistical methods. The results of the proposed method and British Pharmacopoeia method were compared using F and t-statistical tests of significance.

  17. Exogenous Glycine Nitrogen Enhances Accumulation of Glycosylated Flavonoids and Antioxidant Activity in Lettuce (Lactuca sativa L.

    Directory of Open Access Journals (Sweden)

    Xiao Yang

    2017-12-01

    Full Text Available Glycine, the simplest amino acid in nature and one of the most abundant free amino acids in soil, is regarded as a model nutrient in organic nitrogen studies. To date, many studies have focused on the uptake, metabolism and distribution of organic nitrogen in plants, but few have investigated the nutritional performance of plants supplied with organic nitrogen. Lettuce (Lactuca sativa L., one of the most widely consumed leafy vegetables worldwide, is a significant source of antioxidants and bioactive compounds such as polyphenols, ascorbic acid and tocopherols. In this study, two lettuce cultivars, Shenxuan 1 and Lollo Rossa, were hydroponically cultured in media containing 4.5, 9, or 18 mM glycine or 9 mM nitrate (control for 4 weeks, and the levels of health-promoting compounds and antioxidant activity of the lettuce leaf extracts were evaluated. Glycine significantly reduced fresh weight compared to control lettuce, while 9 mM glycine significantly increased fresh weight compared to 4.5 or 18 mM glycine. Compared to controls, glycine (18 mM for Shenxuan 1; 9 mM for Lollo Rossa significantly increased the levels of most antioxidants (including total polyphenols, α-tocopherol and antioxidant activity, suggesting appropriate glycine supply promotes antioxidant accumulation and activity. Glycine induced most glycosylated quercetin derivatives and luteolin derivatives detected and decreased some phenolic acids compared to nitrate treatment. This study indicates exogenous glycine supplementation could be used strategically to promote the accumulation of health-promoting compounds and antioxidant activity of hydroponically grown lettuce, which could potentially improve human nutrition.

  18. Exogenous Glycine Nitrogen Enhances Accumulation of Glycosylated Flavonoids and Antioxidant Activity in Lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Yang, Xiao; Cui, Xiaoxian; Zhao, Li; Guo, Doudou; Feng, Lei; Wei, Shiwei; Zhao, Chao; Huang, Danfeng

    2017-01-01

    Glycine, the simplest amino acid in nature and one of the most abundant free amino acids in soil, is regarded as a model nutrient in organic nitrogen studies. To date, many studies have focused on the uptake, metabolism and distribution of organic nitrogen in plants, but few have investigated the nutritional performance of plants supplied with organic nitrogen. Lettuce ( Lactuca sativa L.), one of the most widely consumed leafy vegetables worldwide, is a significant source of antioxidants and bioactive compounds such as polyphenols, ascorbic acid and tocopherols. In this study, two lettuce cultivars, Shenxuan 1 and Lollo Rossa, were hydroponically cultured in media containing 4.5, 9, or 18 mM glycine or 9 mM nitrate (control) for 4 weeks, and the levels of health-promoting compounds and antioxidant activity of the lettuce leaf extracts were evaluated. Glycine significantly reduced fresh weight compared to control lettuce, while 9 mM glycine significantly increased fresh weight compared to 4.5 or 18 mM glycine. Compared to controls, glycine (18 mM for Shenxuan 1; 9 mM for Lollo Rossa) significantly increased the levels of most antioxidants (including total polyphenols, α-tocopherol) and antioxidant activity, suggesting appropriate glycine supply promotes antioxidant accumulation and activity. Glycine induced most glycosylated quercetin derivatives and luteolin derivatives detected and decreased some phenolic acids compared to nitrate treatment. This study indicates exogenous glycine supplementation could be used strategically to promote the accumulation of health-promoting compounds and antioxidant activity of hydroponically grown lettuce, which could potentially improve human nutrition.

  19. Exogenous hydrogen sulfide promotes cell proliferation and differentiation by modulating autophagy in human keratinocytes

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Xin [Department of Dermatology, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, Heilongjiang Province (China); Dai, Hui [Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, 150001, Heilongjiang Province (China); Zhuang, Binyu [Department of Dermatology, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, Heilongjiang Province (China); Chai, Li; Xie, Yanguang [Institute of Dermatology of Heilongjiang Province, Harbin, 150001, Heilongjiang Province (China); Li, Yuzhen, E-mail: liyuzhen@medmail.com.cn [Department of Dermatology, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, Heilongjiang Province (China)

    2016-04-08

    The effects and the underlying mechanisms of hydrogen sulfide (H{sub 2}S) on keratinocyte proliferation and differentiation are still less known. In the current study, we investigated the effects and the underlying mechanisms of exogenous H{sub 2}S on keratinocyte proliferation and differentiation. Human keratinocytes (HaCaT cells) were treated with various concentrations (0.05, 0.25, 0.5 and 1 mM) of sodium hydrosulfide (NaHS, a donor of H{sub 2}S) for 24 h. A CCK-8 assay was used to assess cell viability. Western blot analysis was performed to determine the expression levels of proteins associated with differentiation and autophagy. Transmission electron microscopy was performed to observe autophagic vacuoles, and flow cytometry was applied to evaluate apoptosis. NaHS promoted the viability, induced the differentiation, and enhanced autophagic activity in a dose-dependent manner in HaCaT cells but had no effect on cell apoptosis. Blockage of autophagy by ATG5 siRNA inhibited NaHS-induced cell proliferation and differentiation. The current study demonstrated that autophagy in response to exogenous H{sub 2}S treatment promoted keratinocyte proliferation and differentiation. Our results provide additional insights into the potential role of autophagy in keratinocyte proliferation and differentiation. - Highlights: • Exogenous H{sub 2}S promotes keratinocyte proliferation and differentiation. • The effects of H{sub 2}S on proliferation and differentiation is modulated by autophagy. • Exogenous H{sub 2}S has no effect on keratinocyte apoptosis.

  20. Effect of Zinc Sulfate and Ascorbic Acid on some Morpho-Physiological Traits of Echinacea purpurea (Purple coneflower under Water Deficit Conditions

    Directory of Open Access Journals (Sweden)

    F Farahvash

    2015-05-01

    Full Text Available To quantify the response of some morpho-physiological traits of Echinacea purpurea to thr application of zinc sulfate and ascorbic acid under water deficit, an experiment was carried out in split plot factorial based on RCBD with three replications at the Agricultural Research Station of Islamic Azad University, Tabriz Branch in 2011-12. Experimental factors consisted of water stress as the main factor with three levels (irrigation after70mm evaporation, irrigation after120mm evaporation and irrigation after 170mm evaporation from class A pan, Secondary factor consisted of: application of microelement with two levels (control and application of zinc sulfate 0.005 concentration and ascorbic acid with four levels (not application, application of 50 mg/l of ascorbic acid, application of 100 mg/l of ascorbic acid and application of 150 mg/l of ascorbic acid. The results showed that the effect of water deficit on purple coneflower caused significant differences in diameter of stem, number of flowering branch, stomata density, zinc concentration of aerial parts plant, fresh weight, relative water content of leaf, LAI, proline concentration, crop growth rate, relative growth rate and net assimilation rate. Comparison of means for water deficits between the different levels of drought stress showed that the maximum LAI, with 2.85, belonged to control. Comparison of means for interaction effects between drought stress and application of zinc sulfate revealed that the maximum proline concentration belonged to spraying plants with zinc sulfate at irrigation after 170mm evaporation from class A pan with 10.16 mg/g.fw. Minimum proline concentration was due to without applying zinc sulfate in complete irrigation (control with 0.08 mg/g.fw. Maximum crop growth rate with 6.77 g/m2.day was was related to control and the minimum, with 4.16 g/m2.day, to irrigation after 170mm. Maximum relative crop growth rate, with 0.19 g/m2.day, belonged to control and the

  1. Causal mediation analysis for longitudinal data with exogenous exposure.

    Science.gov (United States)

    Bind, M-A C; Vanderweele, T J; Coull, B A; Schwartz, J D

    2016-01-01

    Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different types of longitudinal measures of the mediator and outcome, we assume two generalized mixed-effects models for both the mediator and the outcome. The model for the mediator has subject-specific random intercepts and random exposure slopes for each cluster, and the outcome model has random intercepts and random slopes for the exposure, the mediator, and their interaction. We also expand our approach to settings with multiple mediators and derive the mediated effects, jointly through all mediators. Our method requires the absence of time-varying confounding with respect to the exposure and the mediator. This assumption is achieved in settings with exogenous exposure and mediator, especially when exposure and mediator are not affected by variables measured at earlier time points. We apply the methodology to data from the Normative Aging Study and estimate the direct and indirect effects, via DNA methylation, of air pollution, and temperature on intercellular adhesion molecule 1 (ICAM-1) protein levels. Our results suggest that air pollution and temperature have a direct effect on ICAM-1 protein levels (i.e. not through a change in ICAM-1 DNA methylation) and that temperature has an indirect effect via a change in ICAM-1 DNA methylation. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Application of ascorbic acid 2-phosphate as a new voltammetric substrate for alkaline phosphatase determination in human serum

    Directory of Open Access Journals (Sweden)

    Wei Sun

    2005-12-01

    Full Text Available An electrochemical assay of the enzyme alkaline phosphatase (ALP using ascorbic acid 2-phosphate (AAP as a new voltammetric substrate has been described in this paper. In the alkaline buffer solution the ALP enzymatic hydrolysis product of AAP was ascorbic acid (AA, which was an electro-active substance and had a sensitive differential pulse voltammetric (DPV oxidative response on glassy carbon electrode (GCE at +380 mV (versus Ag/AgCl, so the activity of ALP could be monitored voltammetrically of the oxidative peak current of AA. The electrochemical behaviours of AA were carefully studied and the AA standard solution could be measured by DPV method in the linear range from 10.0 to 1000.0 μmol/L with the detection limit of 8.0 μmol/L. The optimal conditions for ALP enzymatic reaction and the voltammetric detection were optimized. Under the optimal conditions the calibration curve for ALP assay exhibited a linear range from 0.4 to 2000.0 U/L with a detection limit of 0.3 U/L. This proposed method was further applied to determine the ALP content in healthy human serum and the results were in good agreement with the traditional p-nitrophenyl phosphate spectrophotometric method. The kinetic constants of enzymatic reaction were also investigated with the apparent kinetic constant Km as 2.77 mmol/L and the maximum velocity Vmax as 0.33 mol/min.

  3. Exogenous spatial attention influences figure-ground assignment.

    Science.gov (United States)

    Vecera, Shaun P; Flevaris, Anastasia V; Filapek, Joseph C

    2004-01-01

    In a hierarchical stage account of vision, figure-ground assignment is thought to be completed before the operation of focal spatial attention. Results of previous studies have supported this account by showing that unpredictive, exogenous spatial precues do not influence figure-ground assignment, although voluntary attention can influence figure-ground assignment. However, in these studies, attention was not summoned directly to a region in a figure-ground display. In three experiments, we addressed the relationship between figure-ground assignment and visuospatial attention. In Experiment 1, we replicated the finding that exogenous precues do not influence figure-ground assignment when they direct attention outside of a figure-ground stimulus. In Experiment 2, we demonstrated that exogenous attention can influence figure-ground assignment if it is directed to one of the regions in a figure-ground stimulus. In Experiment 3, we demonstrated that exogenous attention can influence figure-ground assignment in displays that contain a Gestalt figure-ground cue; this result suggests that figure-ground processes are not entirely completed prior to the operation of focal spatial attention. Exogenous spatial attention acts as a cue for figure-ground assignment and can affect the outcome of figure-ground processes.

  4. Exogenous (automatic) attention to emotional stimuli: a review.

    Science.gov (United States)

    Carretié, Luis

    2014-12-01

    Current knowledge on the architecture of exogenous attention (also called automatic, bottom-up, or stimulus-driven attention, among other terms) has been mainly obtained from studies employing neutral, anodyne stimuli. Since, from an evolutionary perspective, exogenous attention can be understood as an adaptive tool for rapidly detecting salient events, reorienting processing resources to them, and enhancing processing mechanisms, emotional events (which are, by definition, salient for the individual) would seem crucial to a comprehensive understanding of this process. This review, focusing on the visual modality, describes 55 experiments in which both emotional and neutral irrelevant distractors are presented at the same time as ongoing task targets. Qualitative and, when possible, meta-analytic descriptions of results are provided. The most conspicuous result is that, as confirmed by behavioral and/or neural indices, emotional distractors capture exogenous attention to a significantly greater extent than do neutral distractors. The modulatory effects of the nature of distractors capturing attention, of the ongoing task characteristics, and of individual differences, previously proposed as mediating factors, are also described. Additionally, studies reviewed here provide temporal and spatial information-partially absent in traditional cognitive models-on the neural basis of preattention/evaluation, reorienting, and sensory amplification, the main subprocesses involved in exogenous attention. A model integrating these different levels of information is proposed. The present review, which reveals that there are several key issues for which experimental data are surprisingly scarce, confirms the relevance of including emotional distractors in studies on exogenous attention.

  5. Exogenous and endogenous spatial attention effects on visuospatial working memory.

    Science.gov (United States)

    Botta, Fabiano; Santangelo, Valerio; Raffone, Antonino; Lupiáñez, Juan; Belardinelli, Marta Olivetti

    2010-08-01

    In this study, we investigate how exogenous and endogenous orienting of spatial attention affect visuospatial working memory (VSWM). Specifically, we focused on two attentional effects and their consequences on storage in VSWM, when exogenous (Experiment 1) or endogenous (Experiment 2) orienting cues were used. The first effect, known as the meridian effect, is given by a decrement in behavioural performance when spatial cues and targets are presented in locations separated by vertical and/or horizontal meridians. The second effect, known as the distance effect, is given by a decrement in the orienting effects as a function of the spatial distance between cues and targets. Our results revealed a dissociation between exogenous and endogenous orienting mechanisms in terms of both meridian and distance effects. We found that meridian crossing affects performance only when endogenous cues were used. Specifically, VSWM performance with endogenous cueing depended more on the number of meridian crossings than on distance between cue and target. By contrast, a U-shaped distance dependency was observed using exogenous cues. Our findings therefore suggest that exogenous and endogenous orienting mechanisms lead to different forms of attentional bias for storage in VSWM.

  6. On the protection of E.coli against radiation lethality by ascorbate combined with tetracycline

    International Nuclear Information System (INIS)

    Djalali-Behzad, G.; Ehrenberg, L.

    1977-01-01

    The radioprotective action in E.coli ATCC 9637 of ascorbate added to media containing the weak sensitizer, tetracycline (Pittillo, R.F., and Lucas, M.B., 1967, Radiat. Res., vol. 31, 36) was found to be dependent on the presence of metal catalysts of the autoxidation of ascorbate. Thus, the protective action of ascorbate + tetracycline as well as the rate of autoxidation of ascorbate in this mixture were enhanced by 0.1 μM Cu, and these effects were counteracted by pyrophosphate probably through chelation of iron that contaminates phosphate. A suppression of metabolism is apparently involved in the combined action as judged by the decrease of incorporation of labelled uridine. (author)

  7. Enthalpic characteristics of interactions occurring between an ascorbic acid and some saccharides in aqueous solutions

    International Nuclear Information System (INIS)

    Terekhova, Irina V.; Kulikov, Oleg V.; Titova, Elena S.

    2004-01-01

    The enthalpies of solution of mono- and disaccharides were measured in water and aqueous ascorbic acid solutions at 298.15 K using a calorimeter of solution. Enthalpies of transfer of saccharides from water to aqueous ascorbic acid solutions were derived, and enthalpic coefficients of pair interaction h xy were calculated according to MacMillan-Mayer theory. Interactions of ascorbic acid with D-fructose and sucrose are energetically favorable and characterized by negative h xy coefficients while h xy for the interactions occurring between ascorbic acid and α-D glucose, D-galactose and maltose are positive. The obtained results are interpreted in terms of the influence of structure and solvation of solutes on the thermodynamic parameters of their interaction in solutions

  8. Ascorbate oxidase is the potential conductor of a symphony of signaling pathways.

    Science.gov (United States)

    De Tullio, Mario C; Guether, Mike; Balestrini, Raffaella

    2013-03-01

    The functional role of ascorbate oxidase (AO; EC 1.10.3.3) has never been fully explained so far, due to the difficulties in understanding the presence of an enzyme specifically oxidizing ascorbate with no obvious advantage, and the apparent disadvantage of lowering plant stress resistance as a consequence of ascorbate consumption. Here we suggest a complete change of perspective, by proposing an essential role of AO as a modulator of both ascorbate and oxygen content, with relevant implications related to signaling. By affecting the overall redox state, AO is actually involved in redox regulation in the extracellular matrix. In addition, AO can contribute to creating a hypoxic microenvironment, especially relevant in the maintenance of meristem identity and the establishment of mutualistic plant-microbe interactions. We also hypothesize the possible involvement of AO in the activation of a signaling cascade analogous to the mechanism of prolyl hydroxylases/Hypoxia Inducible Factors in animals.

  9. Effect of Combined Intake of Garcinia Kola and Ascorbic Acid on ...

    African Journals Online (AJOL)

    Proximate and nutritional composition of kola nut, garcinia kola and alligator pepper. African Journal ... primarily carried bound to albumin in the blood and only a minor amount is ... increased oxida ve stress. With regular intake, the ascorbic ...

  10. Ascorbic acid effects on in vitro maturation of mouse oocyte with or ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-19

    Oct 19, 2009 ... in origin, that function interactively and synergistically to neutralize free radicals. ... antioxidant properties of ascorbic acid enable it to protect tissues from reactive oxygen ..... Effect of cyclic AMP on the isolated oocytecumulus ...

  11. Role of ascorbic acid on tyrosine hydroxylase activity in the adrenal gland of guinea pig

    Energy Technology Data Exchange (ETDEWEB)

    Nakashima, Y; Sanada, H; Suzue, R; Kawada, S [National Inst. of Nutrition, Tokyo (Japan)

    1976-10-01

    The decrease of tyrosine hydroxylase activity in adrenal homogenate in scurvy was recovered after the administration of ascorbic acid. The causes of the increase in the enzyme activity after the administration of ascorbic acid have been studied. 1. No significant elevation in the enzyme activity was observed after the administration of reserpine to the scorbutic guinea pig. 2. A dose of metal chelating agent, ..cap alpha.., ..cap alpha..'-dipyridyl, prevented the ascorbic acid-induced or reserpine-induced increase in enzyme activity in the scorbutic and the nonscorbutic guinea pigs, respectively. 3. Tyrosine hydroxylase activity was partially recovered by the administration of FeSO/sub 4/ to the scorbutic guinea pig. From these results, it became clear that the induction of tyrosine hydroxylase which was not observed in scurvy was due to the deficiency of Fe/sup 2 +/. These results suggested that ascorbic acid affected the induction of this enzyme via Fe/sup 2 +/.

  12. Role of ascorbic acid on tyrosine hydroxylase activity in the adrenal gland of guinea pig

    International Nuclear Information System (INIS)

    Nakashima, Yoko; Sanada, Hiroo; Suzue, Ryokuero; Kawada, Shoji

    1976-01-01

    The decrease of tyrosine hydroxylase activity in adrenal homogenate in scurvy was recovered after the administration of ascorbic acid. The causes of the increase in the enzyme activity after the administration of ascorbic acid have been studied. 1. No significant elevation in the enzyme activity was observed after the administration of reserpine to the scorbutic guinea pig. 2. A dose of metal chelating agent, α, α'-dipyridyl, prevented the ascorbic acid-induced or reserpine-induced increase in enzyme activity in the scorbutic and the nonscorbutic guinea pigs, respectively. 3. Tyrosine hydroxylase activity was partially recovered by the administration of FeSO 4 to the scorbutic guinea pig. From these results, it became clear that the induction of tyrosine hydroxylase which was not observed in scurvy was due to the deficiency of Fe 2+ . These results suggested that ascorbic acid affected the induction of this enzyme via Fe 2+ . (auth.)

  13. Effect of sodium ascorbate and delayed treatment on the shear bond ...

    African Journals Online (AJOL)

    Background: The effect of bleaching on enamel surfaces, as well as exploring methods of preventing the weakening ..... the calcium, phosphorus, sulfur and potassium content of ... demonstrated the potential protective effect of ascorbic.

  14. Protection of E. coli against radiation lethality by ascorbate combined with tetracycline

    Energy Technology Data Exchange (ETDEWEB)

    Djalali-Behzad, G; Ehrenberg, L [Stockholm Univ. (Sweden). Radiobiologiska Institutionen

    1977-06-01

    The radioprotective action in E.coli ATCC 9637 of ascorbate added to media containing the weak sensitizer, tetracycline (Pittillo, R.F., and Lucas, M.B., 1967, Radiat. Res., vol. 31, 36) was found to be dependent on the presence of metal catalysts of the autoxidation of ascorbate. Thus, the protective action of ascorbate + tetracycline as well as the rate of autoxidation of ascorbate in this mixture were enhanced by 0.1 ..mu..M Cu, and these effects were counteracted by pyrophosphate probably through chelation of iron that contaminates phosphate. A suppression of metabolism is apparently involved in the combined action as judged by the decrease of incorporation of labelled uridine.

  15. Neuronal Rat Brain Damage Caused by Endogenous and Exogenous Hyperthermia

    Directory of Open Access Journals (Sweden)

    Mustafa Aydın

    2012-03-01

    Full Text Available OBJECTIVE: Hyperthermia may induce pathologic alterations within body systems and organs including brain. In this study, neuronal effects of endogenous and exogenous hyperthermia (41°C were studied in rats. METHODS: The endogenous hyperthermia (41°C was induced by lipopolysaccharide and the exogenous by an (electric heater. Possible neuronal damage was evaluated by examining healthy, apoptotic and necrotic cells, and heat shock proteins (HSP 27, HSP 70 in the cerebral cortex, cerebellum and hypothalamus RESULTS: At cellular level, when all neuronal tissues are taken into account; (i a significant increase in the necrotic cells was observed in the both groups (p0.05. CONCLUSION: The neural tissue of brain can show different degree of response to hyperthermia. But we can conclude that endogenous hyperthermia is more harmful to central nervous system than exogenous hyperthermia

  16. [Farmer's lung--a form of exogenous allergic alveolitis].

    Science.gov (United States)

    Sambale, M; Liebetrau, G

    1990-11-15

    Exogenic allergic alveolitides are caused by organic dusts which contain bacteria, moulds or vegetable and animal antigens. The farmer's lung as a form of the exogenic allergic alveolitis is a rare disease. The uncharacteristic symptomatology in the initial phase and in particular the retarded beginning of the symptom after several hours handicap the timely recognition in an early phase of the disease so that curative therapeutic measures are rarely possible. The cases of the disease are found only at the chronic stage, at the stage of the pulmonary fibrosis. Then the prognosis is unfavourable. In the Central Clinic for Heart and Lung Diseases Bad Berka 1,110 patients with alveolitides and lung fibroses were diagnosed in the period from 1975 to 1988. 306 of them could be clarified as exogenic allergic alveolitis, 61 of them (19.8%) were farmer's lungs.

  17. Structure and texture of uranium ores in exogenous deposits

    International Nuclear Information System (INIS)

    Danchev, V.I.

    1977-01-01

    Structure and texture signs of uranium rock exogenous deposits have been systematized for the first time, taking into account the slaging of the ore-formation process, connected with formation and change of containing sedimentary rocks, starting with the sedimentogenesis stage and early sediment diagenesis and their subsequent transformation in katagenesis and metamorphism processes. The main features of uranium geochemistry in the exogenous process are considered. Suggested is the genetic classification of uranium exogenous deposits in rocks of sedimentary cover, made with respect to conjugation and various ore-forming productivity of the litogenesis stage. Described are the main combinations of various rock texture and structure properties, characteristic of deposits of genetic classes and groups of the above classification. Eight most frequently occuring textures (lamellar, concretion, oolitic, coagulate, crack, mixed and impregnated) and their types are described and illustrated. Materials of soviet and foreign authors have been used to compile the atlas

  18. Dynamics of tuberculosis transmission with exogenous reinfections and endogenous reactivation

    Science.gov (United States)

    Khajanchi, Subhas; Das, Dhiraj Kumar; Kar, Tapan Kumar

    2018-05-01

    We propose and analyze a mathematical model for tuberculosis (TB) transmission to study the role of exogenous reinfection and endogenous reactivation. The model exhibits two equilibria: a disease free and an endemic equilibria. We observe that the TB model exhibits transcritical bifurcation when basic reproduction number R0 = 1. Our results demonstrate that the disease transmission rate β and exogenous reinfection rate α plays an important role to change the qualitative dynamics of TB. The disease transmission rate β give rises to the possibility of backward bifurcation for R0 < 1, and hence the existence of multiple endemic equilibria one of which is stable and another one is unstable. Our analysis suggests that R0 < 1 may not be sufficient to completely eliminate the disease. We also investigate that our TB transmission model undergoes Hopf-bifurcation with respect to the contact rate β and the exogenous reinfection rate α. We conducted some numerical simulations to support our analytical findings.

  19. Hemato-biochemical responses to packing in donkeys administered ascorbic acid during the harmattan season

    OpenAIRE

    OLAIFA, Folashade; AYO, Joseph Olusegun; AMBALI, Suleiman Folorunsho; REKWOT, Peter Ibrahim

    2012-01-01

    Experiments were performed to investigate the effect of ascorbic acid (AA) in reducing hemato-biochemical changes in pack donkeys during the cold-dry (harmattan) season. Six experimental donkeys administered orally AA (200 mg/kg) and six control donkeys not administered ascorbic acid were subjected to packing. Blood samples were collected from all donkeys for hematological and biochemical analyses. In the control donkeys, packed cell volume (PCV), erythrocyte count and hemoglobin concentratio...

  20. Over-expression of ascorbate oxidase in the apoplast of transgenic tobacco results in altered ascorbate and glutathione redox states and increased sensitivity to ozone

    DEFF Research Database (Denmark)

    Sanmartin, Maite; Drogoudi, Pavlina D.; Lyons, Tom

    2003-01-01

    overexpressing plants exposed to 100 nmol mol-1 ozone for 7 h day-1 exhibited a substantial increase in foliar injury, and a greater pollutant-induced reduction in both the light-saturated rate of CO2 assimilation and the maximum in vivo rate of ribulose-1,5-bisphosphate carboxylase/oxygenase carboxylation......Transgenic tobacco (Nicotiana tabacum L. cv. Xanthi) plants expressing cucumber ascorbate oxidase (EC.1.10.3.3) were used to examine the role of extracellular ascorbic acid in mediating tolerance to the ubiquitous air pollutant, ozone (O3). Three homozygous transgenic lines, chosen on the basis...

  1. Fructose and Sucrose Intake Increase Exogenous Carbohydrate Oxidation during Exercise

    Science.gov (United States)

    Trommelen, Jorn; Fuchs, Cas J.; Beelen, Milou; Lenaerts, Kaatje; Jeukendrup, Asker E.; Cermak, Naomi M.; van Loon, Luc J. C.

    2017-01-01

    Peak exogenous carbohydrate oxidation rates typically reach ~1 g·min−1 during exercise when ample glucose or glucose polymers are ingested. Fructose co-ingestion has been shown to further increase exogenous carbohydrate oxidation rates. The purpose of this study was to assess the impact of fructose co-ingestion provided either as a monosaccharide or as part of the disaccharide sucrose on exogenous carbohydrate oxidation rates during prolonged exercise in trained cyclists. Ten trained male cyclists (VO2peak: 65 ± 2 mL·kg−1·min−1) cycled on four different occasions for 180 min at 50% Wmax during which they consumed a carbohydrate solution providing 1.8 g·min−1 of glucose (GLU), 1.2 g·min−1 glucose + 0.6 g·min−1 fructose (GLU + FRU), 0.6 g·min−1 glucose + 1.2 g·min−1 sucrose (GLU + SUC), or water (WAT). Peak exogenous carbohydrate oxidation rates did not differ between GLU + FRU and GLU + SUC (1.40 ± 0.06 vs. 1.29 ± 0.07 g·min−1, respectively, p = 0.999), but were 46% ± 8% higher when compared to GLU (0.96 ± 0.06 g·min−1: p exogenous carbohydrate oxidation rates during the latter 120 min of exercise were 46% ± 8% higher in GLU + FRU or GLU + SUC compared with GLU (1.19 ± 0.12, 1.13 ± 0.21, and 0.82 ± 0.16 g·min−1, respectively, p exogenous carbohydrate oxidation rates during prolonged exercise in trained cyclists. PMID:28230742

  2. VEGF-A is increased in exogenous endophthalmitis.

    Science.gov (United States)

    Seamone, Mark E; Lewis, Darrell R; Haidl, Ian D; Gupta, R Rishi; O' Brien, Daniel M; Dickinson, John; Samad, Arif; Marshall, Jean S; Cruess, Alan F

    2017-06-01

    Exogenous endophthalmitis is an ophthalmologic emergency defined by panocular inflammation. Vascular endothelial growth factor A (VEGF-A) contributes to inflammation by promoting chemotaxis of monocytes and granulocytes and by increasing vascular permeability. The purpose of this article is to determine if VEGF-A is elevated in the vitreous samples obtained from individuals with exogenous endophthalmitis. Vitreous samples from individuals with exogenous endophthalmitis (n = 18) were analyzed via Luminex assay and enzyme-linked immunosorbent assay for the cytokines VEGF-A, tumor necrosis factor (TNF), interleukin 6 (IL-6), IL-8 (chemokine [CXCL]-8), IL-1β, IL-10, IL-12p70, IL-33, interferon (IFN)-γ, IFN-α, IFN-β, chemokine ligand (CCL)-3, IL-2, IL-5, IL-15, CXCL-10, CCL-2, IL-1Ra, CCL-5, IL-17, and CCL-11. Vitreous samples obtained at the time of macular hole surgery served as controls (n = 8). Concentrations of VEGF-A were significantly elevated in vitreous samples from individuals with exogenous endophthalmitis compared with macular hole (p exogenous endophthalmitis after cataract surgery (p = 0.001), vitrectomy (p = 0.024), and intravitreal injection (p = 0.012). VEGF-A concentrations were similar in both culture-positive and culture-negative populations (p > 0.05). In a linear regression model, levels of VEGF-A correlated significantly with the chemokine CXCL-8 (p = 0.028). We demonstrate that VEGF-A is potently upregulated in exogenous endophthalmitis. This observation provides a foundation for future studies of targeted VEGF-A blockade in the management of endophthalmitis. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

  3. The effects of Α-tocopherol and ascorbic acid glucosides on radiation- and H2O2-induced decomposition of thymine in aqueous solution

    International Nuclear Information System (INIS)

    Brinkevich, S.D.; Lagutin, P.Yu.; Shadyro, O.I.

    2008-01-01

    The effects of ascorbic acid, ascorbic acid glycoside and α-tocopherol monoglycoside on radiation- and H 2 O 2 -induced decomposition of thymine in aqueous solutions were investigated. Of the three compounds studied, ascorbic acid glycoside was found to possess the most marked protecting properties. An explanation of this phenomenon has been given in terms of differences in molecular structures of ascorbic acid and ascorbic acid glycoside, as well as properties of radical adducts formed during their interaction with OH radicals. (authors)

  4. Application of bone marrow and adipose-derived mesenchymal stem cells for testing the biocompatibility of metal-based biomaterials functionalized with ascorbic acid

    International Nuclear Information System (INIS)

    Marycz, Krzysztof; Śmieszek, Agnieszka; Grzesiak, Jakub; Donesz-Sikorska, Anna; Krzak-Roś, Justyna

    2013-01-01

    In this study, metal-based biomaterials were functionalized with ascorbic acid (LAA). Two types of substrates were used: austenitic steel 316L and titanium Ti6Al4V. Coatings were prepared with the sol–gel method and applied on metal surfaces using the dip-coating technique. Ascorbic acid was delivered with SiO 2 -coating at concentrations of 0.1 and 0.4 M. The morphology of the surfaces and coatings was determined using scanning electron microscope (SEM), whereas their elemental composition by SEM-EDX. Immobilization of ascorbic acid in the coatings was confirmed with Raman spectroscopy. The biocompatibility of the materials obtained was tested in vitro using both bone marrow- and adipose-derived mesenchymal stem cells (BMMSC and ADMSC, respectively). Proliferation rate and morphology of cells cultured in the presence of designed biomaterials were monitored after 24, 48, 120 and 168 h of propagation. The results obtained indicated that silica coatings doped with 0.4 M LAA had a positive effect on the proliferation rate of investigated cells, and in some cases on the growth pattern of culture. (paper)

  5. Culturing bone marrow cells with dexamethasone and ascorbic acid improves osteogenic cell sheet structure.

    Science.gov (United States)

    Akahane, M; Shimizu, T; Kira, T; Onishi, T; Uchihara, Y; Imamura, T; Tanaka, Y

    2016-11-01

    To assess the structure and extracellular matrix molecule expression of osteogenic cell sheets created via culture in medium with both dexamethasone (Dex) and ascorbic acid phosphate (AscP) compared either Dex or AscP alone. Osteogenic cell sheets were prepared by culturing rat bone marrow stromal cells in a minimal essential medium (MEM), MEM with AscP, MEM with Dex, and MEM with Dex and AscP (Dex/AscP). The cell number and messenger (m)RNA expression were assessed in vitro, and the appearance of the cell sheets was observed after mechanical retrieval using a scraper. β-tricalcium phosphate (β-TCP) was then wrapped with the cell sheets from the four different groups and subcutaneously implanted into rats. After mechanical retrieval, the osteogenic cell sheets from the MEM, MEM with AscP, and MEM with Dex groups appeared to be fragmented or incomplete structures. The cell sheets cultured with Dex/AscP remained intact after mechanical retrieval, without any identifiable tears. Culture with Dex/AscP increased the mRNA and protein expression of extracellular matrix proteins and cell number compared with those of the other three groups. More bridging bone formation was observed after transplantation of the β-TCP scaffold wrapped with cell sheets cultured with Dex/AscP, than in the other groups. These results suggest that culture with Dex/AscP improves the mechanical integrity of the osteogenic cell sheets, allowing retrieval of the confluent cells in a single cell sheet structure. This method may be beneficial when applied in cases of difficult tissue reconstruction, such as nonunion, bone defects, and osteonecrosis.Cite this article: M. Akahane, T. Shimizu, T. Kira, T. Onishi, Y. Uchihara, T. Imamura, Y. Tanaka. Culturing bone marrow cells with dexamethasone and ascorbic acid improves osteogenic cell sheet structure. Bone Joint Res 2016;5:569-576. DOI: 10.1302/2046-3758.511.BJR-2016-0013.R1. © 2016 Akahane et al.

  6. Kinetics of degradation of ascorbic acid by cyclic voltammetry method

    Directory of Open Access Journals (Sweden)

    Grudić Veselinka V.

    2015-01-01

    Full Text Available Cyclic voltammetry was used to examine the kinetics of degradation of ascorbic acid (AA at different temperatures. It has been shown that the reduction of the concentration of AA in all temperatures follow the kinetics of the first order reaction. The rate constant of the oxidation reaction increases with temperature as follows: 5x10-5; 2x10-4; 1x10-3 and 3x10-3 min-1 at temperatures of 25°C, 35°C, 65°C and 90°C, respectively. The temperature dependence of the rate constant follows Arrhenius equation, and the value of activation energy of the reaction degradation is 48.2 kJ mol-1 . The effect of storage time at a temperature of 90 °C on AA content in fresh juice of green peppers was investigated. It was shown that AA oxidation reaction in the juice is also the first order reaction, while the lower rate constant in relation to the pure AA (5x10-3 min-1 indicates the influence of other substances present in peppers.

  7. Ascorbic acid (AA) metabolism in protection against radiation damage

    International Nuclear Information System (INIS)

    Rose, R.C.; Koch, M.J.

    1986-01-01

    The possibility is considered that AA protects tissues against radiation damage by scavenging free radicals that result from radiolysis of water. A physiologic buffer (pH 6.7) was incubated with 14 C-AA and 1 mM thiourea (to slow spontaneous oxidation of AA). Aliquots were assayed by HPLC and scintillation spectrometry to identify the 14 C-label. Samples exposed to Cobalt-60 radiation had a half time of AA decay of 30 minutes) indicating that AA scavenges radiation-induced free radicals and forms the ascorbate free radical (AFR). Pairs of 14 C-AFR disproportionate, with the net effect of 14 C-dehydroascorbic acid formation from 14 C-AA. Having established that AFR result from ionizing radiation in an aqueous solution, the possibility was evaluated that a tissue factor reduces AFR. Cortical tissue from the kidneys of male rats was minced, homogenized in buffer and centrifuged at 8000 xg. The supernatant was found to slow the rate of radiation-induced AA degradation by > 90% when incubated at 23 0 C in the presence of 15 μM 14 C-AA. Samples of supernatant maintained at 100 0 C for 10 minutes or precipitated with 5% PCA did not prevent radiation-induced AA degradation. AA may have a specific role in scavenging free radicals generated by ionizing radiation and thereby protect body tissues

  8. Neuropsychiatric findings in Cushing syndrome and exogenous glucocorticoid administration.

    Science.gov (United States)

    Starkman, Monica N

    2013-09-01

    This article reviews the neuropsychiatric presentations elicited by spontaneous hypercortisolism and exogenous supraphysiologic glucocorticoids. Patients with Cushing disease and syndrome develop a depressive syndrome: irritable and depressed mood, decreased libido, disrupted sleep and cognitive decrements. Exogenous short-term glucocorticoid administration may elicit a hypomanic syndrome with mood, sleep and cognitive disruptions. Treatment options are discussed. Brain imaging and neuropsychological studies indicate elevated cortisol and other glucocorticoids are especially deleterious to hippocampus and frontal lobe. The research findings also shed light on neuropsychiatric abnormalities in conditions that have substantial subgroups exhibiting elevated and dysregulated cortisol: aging, major depressive disorder and Alzheimer's disease. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Kinetics of ascorbic acid degradation in un-pasteurized Iranian lemon juice during regular storage conditions.

    Science.gov (United States)

    Abbasi, A; Niakousari, M

    2008-05-15

    The aim of this research was to determine shelf life stability of un-pasteurized lemon juice filled in clear or dark green glass bottles. Presence of light, time and temperature affect the ascorbic acid retention in citrus juices. Bottles were stored at room temperature (27 +/- 3 degrees C) and in the refrigerator (3 +/- 1 degrees C). Total soluble solids, total titrable acidity and pH value were measured every three weeks and analysis was carried out on ascorbic acid content by means of titration method in the presence of 2,6-dichlorophenol indophenol. The study was carried out for 12 weeks after which slight changes in color, taste and apparent texture in some samples were observed and ascorbic acid content reduced by 50%. Soluble solids content, pH value and total acidity were 5.5 degrees Brix, 2.73 and 5 g/100 mL, respectively which appeared not to be significantly influenced by storage time or conditions. Ascorbic acid content initially at 38.50 mg/100 mL was sharply reduced to about 22 mg/100 mL within the first three weeks of storage. The final ascorbic acid content of all samples was about 15 mg/100 mL. The deteriorative reaction of ascorbic acid in the juice at all conditions followed a first-order kinetic model with activation energy of 137 cal mol(-1).

  10. Ascorbate enhances u.v.-mutagenesis in E. coli but inhibits it in Chinese hamster cells

    International Nuclear Information System (INIS)

    Rossman, T.G.; Klein, C.B.; Naslund, M.

    1986-01-01

    Ascorbic acid (vitamin C) causes an increase in the mutation frequency of u.v.-irradiated Escherichia coli WP2. The enhancement occurs at all u.v. fluences, and is dependent upon the ascorbate concentration in the medium. A maximum effect (approx. 8- to 13-fold) is seen at 100-150 μg/ml, although some enhancement can be seen even at 10 μg/ml. The comutagenic effect of ascorbate with u.v. in E. coli is dependent upon peptone, a constituent of nutrient broth. The enhancement of u.v.-mutagenesis by ascorbate is absent in strains WP2sub(s) (uvrA) amd WP6 (polA), suggesting that ascorbate affects the repair of pyrimidine dimers. The opposite results are observed for u.v.-mutagenesis in Chinese hamster V79 cells. The presence of ascorbate (50 μg/ml) during u.v. irradiation does not enhance the u.v. effect, but rather decreases it approx. 30%. These results are discussed with regard to differences in the mechanism of u.v.-mutagenesis and DNA repair in bacterial and mammalian cells. (author)

  11. Ascorbic acid prevents vascular dysfunction induced by oral glucose load in healthy subjects.

    Science.gov (United States)

    De Marchi, Sergio; Prior, Manlio; Rigoni, Anna; Zecchetto, Sara; Rulfo, Fanny; Arosio, Enrico

    2012-01-01

    To examine the effects of oral glucose load on forearm circulatory regulation before and after ascorbic acid administration in healthy subjects. Microcirculation study with laser Doppler was performed at the hand in basal conditions, after ischemia and after acetylcholine and nitroprusside; strain gauge plethysmography was performed at basal and after ischemia. The tests were repeated in the same sequence 2 hour after oral administration of glucose (75 g). The subjects were randomised for administration of ascorbic acid (1 g bid) or placebo (sodium bicarbonate 1 g bid) for 10 days. After that, the tests were repeated before and after a new oral glucose load. Blood pressure and heart rate were monitored. Macrocirculatory flux, pressure values and heart rate were unvaried throughout the study. The glucose load caused a reduction in the hyperemic peak flow with laser Doppler and plethysmography; it reduced flux recovery time and hyperemic curve area after ischemia; acetylcholine elicited a minor increase in flux with laser Doppler. The response to nitroprusside was unvaried after glucose load as compared to basal conditions. Treatment with ascorbic acid prevented the decrease in hyperemia after glucose, detected with laser Doppler and plethysmography. Ascorbic acid prevented the decreased response to acetylcholine after glucose, the response to nitroprusside was unaffected by ascorbic acid. Results after placebo were unvaried. Oral glucose load impairs endothelium dependent dilation and hyperaemia at microcirculation, probably via oxidative stress; ascorbic acid can prevent it. Copyright © 2011 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  12. Application of titanium oxide nanotube films containing gold nanoparticles for the electroanalytical determination of ascorbic acid

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Mir Ghasem, E-mail: mg-hosseini@tabrizu.ac.ir; Faraji, Masoud; Momeni, Mohamad Mohsen

    2011-03-31

    Au/TiO{sub 2}/Ti electrodes have been prepared by galvanic deposition of gold particles on TiO{sub 2} nanotube substrates. Titanium oxide nanotubes are fabricated by anodizing titanium foil in a Dimethyl Sulfoxide electrolyte containing fluoride. The scanning electron microscopy results indicated that gold particles are homogeneously deposited on the surface of TiO{sub 2} nanotubes. The TiO{sub 2} layers consist of individual tubes of about 40-80 nm diameters. The electro-catalytic behavior of Au/TiO{sub 2}/Ti and flat gold electrodes for the ascorbic acid electro-oxidation was studied by cyclic voltammetry. The results showed that the flat gold electrode is not suitable for the oxidation of ascorbic acid. However, the Au/TiO{sub 2}/Ti electrodes are shown to possess catalytic activity toward the oxidation reaction. Catalytic oxidation peak current showed a linear dependence on the ascorbic acid concentration and a linear calibration curve is obtained in the concentration range of 1-5 mM of ascorbic acid. Also, determination of ascorbic acid in real samples was evaluated. The obtained results were found to be satisfactory. Finally the effects of interference on the detection of ascorbic acid were investigated.

  13. Ascorbic acid enables reversible dopamine receptor 3H-agonist binding

    International Nuclear Information System (INIS)

    Leff, S.; Sibley, D.R.; Hamblin, M.; Creese, I.

    1981-01-01

    The effects of ascorbic acid on dopaminergic 3 H-agonist receptor binding were studied in membrane homogenates of bovine anterior pituitary and caudate, and rat striatum. In all tissues virtually no stereospecific binding (defined using 1uM (+)butaclamol) of the 3 H-agonists N-propylnorapomorphine (NPA), apomorphine, or dopamine could be demonstrated in the absence of ascorbic acid. Although levels of total 3 H-agonist binding were three to five times greater in the absence than in the presence of 0.1% ascorbic acid, the increased binding was entirely non-stereospecific. Greater amounts of dopamine-inhibitable 3 H-NPA binding could be demonstrated in the absence of 0.1% ascorbic acid, but this measure of ''specific binding'' was demonstrated not to represent dopamine receptor binding since several other catecholamines and catechol were equipotent with dopamine and more potent than the dopamine agonist (+/-)amino-6,7-dihydroxy-1,2,3,4-tetrahydronapthalene (ADTN) in inhibiting this binding. High levels of dopamine-displaceable 3 H-agonist binding were detected in fresh and boiled homogenates of cerebellum, an area of brain which receives no dopaminergic innervation, further demonstrating the non-specific nature of 3 H-agonist binding in the absence of ascorbic acid. These studies emphasize that under typical assay conditions ascorbic acid is required in order to demonstrate reversible and specific 3 H-agonist binding to dopamine receptors

  14. Pretreatment with ascorbic acid prevents lethal gastrointestinal syndrome in mice receiving a massive amount of radiation

    International Nuclear Information System (INIS)

    Yamamoto, Tetsuo; Kinoshita, Manabu; Shinomiya, Nariyoshi; Hiroi, Sadayuki; Sugasawa, Hidekazu; Majima, Takashi; Seki, Shuhji; Matsushita, Yoshitaro; Saitoh, Daizoh

    2010-01-01

    While bone marrow or stem cell transplantation can rescue bone marrow aplasia in patients accidentally exposed to a lethal radiation dose, radiation-induced irreversible gastrointestinal damage (GI syndrome) is fatal. We investigated the effects of ascorbic acid on radiation-induced GI syndrome in mice. Ascorbic acid (150 mg/kg/day) was orally administered to mice for 3 days, and then the mice underwent whole body irradiation (WBI). Bone marrow transplantation (BMT) 24 h after irradiation rescued mice receiving a WBI dose of less than 12 Gy. No mice receiving 14 Gy-WBI survived, because of radiation-induced GI syndrome, even if they received BMT. However, pretreatment with ascorbic acid significantly suppressed radiation-induced DNA damage in the crypt cells and prevented denudation of intestinal mucosa; therefore, ascorbic acid in combination with BMT rescued mice after 14 Gy-WBI. DNA microarray analysis demonstrated that irradiation up-regulated expressions of apoptosis-related genes in the small intestine, including those related to the caspase-9-mediated intrinsic pathway as well as the caspase-8-mediated extrinsic pathway, and down-regulated expressions of these genes in ascorbic acid-pretreated mice. Thus, pretreatment with ascorbic acid may effectively prevent radiation-induced GI syndrome. (author)

  15. Combined effect of selenium and ascorbic acid on alcohol induced hyperlipidemia in male guinea pigs.

    Science.gov (United States)

    Asha, G S; Indira, M

    2004-02-01

    Alcoholics usually suffer from malnutrition and are especially deficient in micronutrients like vitamin C, selenium and Zn. In the present study, combined effects of selenium and ascorbic acid on alcohol-induced hyperlipidemia were studied in guinea pigs. Four groups of male guinea pigs were maintained for 45 days as follows: control (1 mg ascorbate (AA)/100 g body mass/day), ethanol (900 mg ethanol/100 g body mass + 1 mg AA/100 g body mass/day), selenium+ascorbic acid [(25 mg AA + 0.05 mg Se)/100 g body mass/day], ethanol+selenium+ascorbic acid [(25 mg AA + 0.05 mg Se + 900 mg ethanol)/100 g body mass/day]. Co-administration of selenium and ascorbic acid along with alcohol reduced the concentration of all lipids, as also evidenced from the decreased activities of hydroxymethylglutaryl-CoA reductase and enhanced activities of plasma lecithin cholesterol acyl transferase and lipoprotein lipase. Concentrations of bile acids were increased. We conclude that the supplementation of Se and ascorbic acid reduced alcohol induced hyperlipidemia, by decreased synthesis and increased catabolism.

  16. Old Things New View: Ascorbic Acid Protects the Brain in Neurodegenerative Disorders

    Directory of Open Access Journals (Sweden)

    Adriana Covarrubias-Pinto

    2015-11-01

    Full Text Available Ascorbic acid is a key antioxidant of the Central Nervous System (CNS. Under brain activity, ascorbic acid is released from glial reservoirs to the synaptic cleft, where it is taken up by neurons. In neurons, ascorbic acid scavenges reactive oxygen species (ROS generated during synaptic activity and neuronal metabolism where it is then oxidized to dehydroascorbic acid and released into the extracellular space, where it can be recycled by astrocytes. Other intrinsic properties of ascorbic acid, beyond acting as an antioxidant, are important in its role as a key molecule of the CNS. Ascorbic acid can switch neuronal metabolism from glucose consumption to uptake and use of lactate as a metabolic substrate to sustain synaptic activity. Multiple evidence links oxidative stress with neurodegeneration, positioning redox imbalance and ROS as a cause of neurodegeneration. In this review, we focus on ascorbic acid homeostasis, its functions, how it is used by neurons and recycled to ensure antioxidant supply during synaptic activity and how this antioxidant is dysregulated in neurodegenerative disorders.

  17. Unveiling the water-associated conformational mobility in the active site of ascorbate peroxidase.

    Science.gov (United States)

    Chao, Wei-Chih; Lin, Li-Ju; Lu, Jyh-Feng; Wang, Jinn-Shyan; Lin, Tzu-Chieh; Chen, Yi-Han; Chen, Yi-Ting; Yang, Hsiao-Ching; Chou, Pi-Tai

    2018-03-01

    We carried out comprehensive spectroscopic studies of wild type and mutants of ascorbate peroxidase (APX) to gain understanding of the conformational mobility of the active site. In this approach, three unnatural tryptophans were applied to replace the distal tryptophan (W41) in an aim to probe polarity/water environment near the edge of the heme-containing active site. 7-azatryptophan ((7-aza)Trp) is sensitive to environment polarity, while 2,7-azatryptophan ((2,7-aza)Trp) and 2,6-diazatryptophan ((2,6-aza)Trp) undergo excited-state water-catalyzed double and triple proton transfer, respectively, and are sensitive to the water network. The combination of their absorption, emission bands and the associated relaxation dynamics of these fluorescence probes, together with the Soret-band difference absorption and resonance Raman spectroscopy, lead us to unveil the water associated conformational mobility in the active site of APX. The results are suggestive of the existence of equilibrium between two different environments surrounding W41 in APX, i.e., the water-rich and water-scant forms with distinct fluorescence relaxation. Our results thus demonstrate for the first time the power of integrating multiple sensors (7-aza)Trp, (2,7-aza)Trp and (2,6-aza)Trp in probing the water environment of a specifically targeted Trp in proteins. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Polyethyleneimine-templated copper nanoclusters via ascorbic acid reduction approach as ferric ion sensor

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jie; Ju, Yuyun; Liu, Juanjuan; Zhang, Huige [State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Chen, Xingguo, E-mail: chenxg@lzu.edu.cn [State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Lanzhou 730000 (China)

    2015-01-07

    Highlights: • A new method for synthesis of the BPEI-CuNCs is established. • A facile approach for Fe{sup 3+} ion sensing by fluorescence quenching is developed. • The method for Fe{sup 3+} sensing has high sensitivity and excellent selectivity. - Abstract: In this report we reported a facile one-pot method for synthesis of water-soluble and stable fluorescent CuNCs at room temperature, in which branched polyethyleneimine (BPEI) served as capping scaffold and ascorbic acid as reducing agent. The prepared BPEI-CuNCs exhibited excellent properties such as good water-solubility, photostability and high stability toward high ionic strength. Based on the electron transfer induced fluorescence quenching mechanism, this fluorescence probe was used for the sensitive and selective determination of ferric ions (Fe{sup 3+}) in aqueous solution. The limit of detection was 340 nM in the linear range of 0.5–1000 μM, which was lower than the maximum level of Fe{sup 3+} permitted in drinking water by the U.S. Environmental Protection Agency. The method was successfully applied to the detection of Fe{sup 3+} in tap water, Yellow River water and human urine samples with the quantitative spike recoveries ranging from 95.3% to 112.0%.

  19. Seed-mediated grown silver nanoparticles as a colorimetric sensor for detection of ascorbic acid

    Science.gov (United States)

    Rostami, Simindokht; Mehdinia, Ali; Jabbari, Ali

    2017-06-01

    A simple and sensitive approach was demonstrated for detection of ascorbic acid (AA) based on seed-mediated growth of silver nanoparticles (Ag NPs). According to the seeding strategy, silver ions existing in the growth solution were reduced to silver atoms on the surface of silver seeds via redox reaction between silver ions and AA. This process -led to appear an absorption band in near 420 nm owing to the localized surface plasmon resonance peak of the generated Ag NPs. This change in absorption spectra of Ag NPs caused a change in color of the mixture from colorless to yellow. It was found that the changes in absorption intensity at 420 nm have a good relationship with the concentration of AA. Also, detection of AA was achieved through the established colorimetric sensor in the range of 0.25-25 μM with detection limit of 0.054 μM. Moreover, the selectivity of the method was evaluated with considering potential interferences. The method showed high selectivity toward AA rather than potential interferences and coexisted molecules with AA. It was successfully applied for detection and determination of AA in pharmaceutical tablets and commercial lemonade.

  20. Polyethyleneimine-templated copper nanoclusters via ascorbic acid reduction approach as ferric ion sensor

    International Nuclear Information System (INIS)

    Feng, Jie; Ju, Yuyun; Liu, Juanjuan; Zhang, Huige; Chen, Xingguo

    2015-01-01

    Highlights: • A new method for synthesis of the BPEI-CuNCs is established. • A facile approach for Fe 3+ ion sensing by fluorescence quenching is developed. • The method for Fe 3+ sensing has high sensitivity and excellent selectivity. - Abstract: In this report we reported a facile one-pot method for synthesis of water-soluble and stable fluorescent CuNCs at room temperature, in which branched polyethyleneimine (BPEI) served as capping scaffold and ascorbic acid as reducing agent. The prepared BPEI-CuNCs exhibited excellent properties such as good water-solubility, photostability and high stability toward high ionic strength. Based on the electron transfer induced fluorescence quenching mechanism, this fluorescence probe was used for the sensitive and selective determination of ferric ions (Fe 3+ ) in aqueous solution. The limit of detection was 340 nM in the linear range of 0.5–1000 μM, which was lower than the maximum level of Fe 3+ permitted in drinking water by the U.S. Environmental Protection Agency. The method was successfully applied to the detection of Fe 3+ in tap water, Yellow River water and human urine samples with the quantitative spike recoveries ranging from 95.3% to 112.0%

  1. Drought and exogenous abscisic acid alter hydrogen peroxide accumulation and differentially regulate the expression of two maize RD22-like genes.

    Science.gov (United States)

    Phillips, Kyle; Ludidi, Ndiko

    2017-08-18

    Increased biosynthesis of abscisic acid (ABA) occurs in plants in response to water deficit, which is mediated by changes in the levels of reactive oxygen species such as H 2 O 2 . Water deficit and ABA induce expression of some RD22-like proteins. This study aimed to evaluate the effect of water deficit and exogenous ABA (50 µM ABA applied every 24 hours for a total of 72 hours) on H 2 O 2 content in Zea mays (maize) and to characterise genes encoding two putative maize RD22-like proteins (designated ZmRD22A and ZmRD22B). The expression profiles of the two putative maize RD22-like genes in response to water deficit and treatment with ABA were examined in leaves. In silico analyses showed that the maize RD22-like proteins share domain organisation with previously characterized RD22-like proteins. Both water deficit and exogenous ABA resulted in increased H 2 O 2 content in leaves but the increase was more pronounced in response to water deficit than to exogenous ABA. Lignin content was not affected by exogenous ABA, whereas it was decreased by water deficit. Expression of both RD22-like genes was up-regulated by drought but the ZmRD22A gene was not influenced by exogenous ABA, whereas ZmRD22B was highly responsive to exogenous ABA.

  2. Exogenous insulin antibody syndrome (EIAS): a clinical syndrome associated with insulin antibodies induced by exogenous insulin in diabetic patients.

    Science.gov (United States)

    Hu, Xiaolei; Chen, Fengling

    2018-01-01

    Insulin has been used for diabetes therapy and has achieved significant therapeutic effect. In recent years, the use of purified and recombinant human insulin preparations has markedly reduced, but not completely suppressed, the incidence of insulin antibodies (IAs). IAs induced by exogenous insulin in diabetic patients is associated with clinical events, which is named exogenous insulin antibody syndrome (EIAS). The present review is based on our research and summarizes the characterization of IAs, the factors affecting IA development, the clinical significance of IAs and the treatments for EIAS. © 2018 The authors.

  3. The influence of endogenous and exogenous sex hormones on systemic lupus erythematosus in pre- and postmenopausal women

    Directory of Open Access Journals (Sweden)

    Bogna Grygiel-Górniak

    2014-09-01

    Full Text Available Systemic lupus erythematosus (SLE or lupus is a chronic inflammatory disease that occurs mainly in women. Typically, symptoms appear within the first few years of adolescence, but currently an increase can be observed in the percentage of postmenopausal women with this condition. This is possibly due to the sophisticated treatment of the disease, which significantly improves the survival curve and prognosis. Genetic and environmental factors are involved in the development of SLE. Both regulation of the immune system and the activity of this disease are influenced by a variety of hormones, including: 17-estradiol, testosterone, prolactin, progesterone and dehydroepiandrosterone (DHEA. Early menarche, menstrual cyclicity, the total number of years characterized by ovulatory cycles and early menopause are correlated with the development of SLE. Because of the health risks, attempts are increasingly being made to evaluate the impact of exogenous hormones (especially those applied exogenously on the course of SLE. In particular, the role of estrogens is being highlighted, either endo- or exogenous, including oral contraceptives (OC, therapy used in the treatment of infertility, and hormonal replacement therapy (HRT. The purpose of this manuscript is the revision of the literature concerning the impact of both endo- and exogenous estrogens on the development of lupus, inducement of flares and any possible complications.

  4. The influence of endogenous and exogenous sex hormones on systemic lupus erythematosus in pre- and postmenopausal women.

    Science.gov (United States)

    Grygiel-Górniak, Bogna; Puszczewicz, Mariusz Jacek

    2014-09-01

    Systemic lupus erythematosus (SLE or lupus) is a chronic inflammatory disease that occurs mainly in women. Typically, symptoms appear within the first few years of adolescence, but currently an increase can be observed in the percentage of postmenopausal women with this condition. This is possibly due to the sophisticated treatment of the disease, which significantly improves the survival curve and prognosis. Genetic and environmental factors are involved in the development of SLE. Both regulation of the immune system and the activity of this disease are influenced by a variety of hormones, including: 17β-estradiol, testosterone, prolactin, progesterone and dehydroepiandrosterone (DHEA). Early menarche, menstrual cyclicity, the total number of years characterized by ovulatory cycles and early menopause are correlated with the development of SLE. Because of the health risks, attempts are increasingly being made to evaluate the impact of exogenous hormones (especially those applied exogenously) on the course of SLE. In particular, the role of estrogens is being highlighted, either endo- or exogenous, including oral contraceptives (OC), therapy used in the treatment of infertility, and hormonal replacement therapy (HRT). The purpose of this manuscript is the revision of the literature concerning the impact of both endo- and exogenous estrogens on the development of lupus, inducement of flares and any possible complications.

  5. Effects of whey, molasses and exogenous enzymes on the ensiling ...

    African Journals Online (AJOL)

    The study was conducted to assess the effects of whey, molasses and exogenous enzymes on fermentation, aerobic stability and nutrient composition of ensiled maize cobs. Five treatments were ensiled in 1.5 L anaerobic glass jars over 32 days, namely i) control (maize cobs without additives (CON); ii) maize cobs with ...

  6. Endogenous versus Exogenous Growth Factor Regulation of Articular Chondrocytes

    Science.gov (United States)

    Shi, Shuiliang; Chan, Albert G.; Mercer, Scott; Eckert, George J.; Trippel, Stephen B.

    2014-01-01

    Anabolic growth factors that regulate the function of articular chondrocytes are candidates for articular cartilage repair. Such factors may be delivered by pharmacotherapy in the form of exogenous proteins, or by gene therapy as endogenous proteins. It is unknown whether delivery method influences growth factor effectiveness in regulating articular chondrocyte reparative functions. We treated adult bovine articular chondrocytes with exogenous recombinant insulin-like growth factor-I (IGF-I) and transforming growth factor-beta1 (TGF-β1), or with the genes encoding these growth factors for endogenous production. Treatment effects were measured as change in chondrocyte DNA content, glycosaminoglycan production, and aggrecan gene expression. We found that IGF-I stimulated chondrocyte biosynthesis similarly when delivered by either exogenous or endogenous means. In contrast, exogenous TGF-ß1 stimulated these reparative functions, while endogenous TGF-ß1 had little effect. Endogenous TGF-ß1 became more bioactive following activation of the transgene protein product. These data indicate that effective mechanisms of growth factor delivery for articular cartilage repair may differ for different growth factors. In the case of IGF-I, gene therapy or protein therapy appear to be viable options. In contrast, TGF-ß1 gene therapy may be constrained by a limited ability of chondrocytes to convert latent complexes to an active form. PMID:24105960

  7. Cassava Leaf Meal and Exogenous Enzyme as Supplements in ...

    African Journals Online (AJOL)

    %, 50% and 66.67% such that the levels of cassava leaf meal (CLM) supplementation were 5%, 7.5% and 10% but in addition Avizyme® (an exogenous commercial polysaccharidase) was added to the diets at the rate of 100g kg-1. The birds ...

  8. Accounting for Exogenous Influences in Performance Evaluations of Teachers

    Science.gov (United States)

    De Witte, Kristof; Rogge, Nicky

    2011-01-01

    Students' evaluations of teacher performance (SETs) are increasingly used by universities. However, SETs are controversial mainly due to two issues: (1) teachers value various aspects of excellent teaching differently, and (2) SETs should not be determined on exogenous influences. Therefore, this paper constructs SETs using a tailored version of…

  9. Do Endogenous and Exogenous Action Control Compete for Perception?

    Science.gov (United States)

    Pfister, Roland; Heinemann, Alexander; Kiesel, Andrea; Thomaschke, Roland; Janczyk, Markus

    2012-01-01

    Human actions are guided either by endogenous action plans or by external stimuli in the environment. These two types of action control seem to be mediated by neurophysiologically and functionally distinct systems that interfere if an endogenously planned action suddenly has to be performed in response to an exogenous stimulus. In this case, the…

  10. Do endogenous and exogenous action control compete for perception?

    Science.gov (United States)

    Pfister, Roland; Heinemann, Alexander; Kiesel, Andrea; Thomaschke, Roland; Janczyk, Markus

    2012-04-01

    Human actions are guided either by endogenous action plans or by external stimuli in the environment. These two types of action control seem to be mediated by neurophysiologically and functionally distinct systems that interfere if an endogenously planned action suddenly has to be performed in response to an exogenous stimulus. In this case, the endogenous representation has to be deactivated first to give way to the exogenous system. Here we show that interference of endogenous and exogenous action control is not limited to motor-related aspects but also affects the perception of action-related stimuli. Participants associated two actions with contingent sensory effects in learning blocks. In subsequent test blocks, preparing one of these actions specifically impaired responding to the associated effect in an exogenous speeded detection task, yielding a blindness-like effect for arbitrary, learned action effects. In accordance with the theory of event coding, this finding suggests that action planning influences perception even in the absence of any physical similarities between action and to-be-perceived stimuli.

  11. Exogenous ethylene inhibits sprout growth in onion bulbs.

    Science.gov (United States)

    Bufler, Gebhard

    2009-01-01

    Exogenous ethylene has recently gained commercial interest as a sprouting inhibitor of onion bulbs. The role of ethylene in dormancy and sprouting of onions, however, is not known. A cultivar (Allium cepa 'Copra') with a true period of dormancy was used. Dormant and sprouting states of onion bulbs were treated with supposedly saturating doses of ethylene or with the ethylene-action inhibitor 1-methylcyclopropene (1-MCP). Initial sprouting was determined during storage at 18 degrees C by monitoring leaf blade elongation in a specific size class of leaf sheaths. Changes in ATP content and sucrose synthase activity in the sprout leaves, indicators of the sprouting state, were determined. CO(2) and ethylene production of onion bulbs during storage were recorded. Exogenous ethylene suppressed sprout growth of both dormant and already sprouting onion bulbs by inhibiting leaf blade elongation. In contrast to this growth-inhibiting effect, ethylene stimulated CO(2) production by the bulbs about 2-fold. The duration of dormancy was not significantly affected by exogenous ethylene. However, treatment of dormant bulbs with 1-MCP caused premature sprouting. Exogenous ethylene proved to be a powerful inhibitor of sprout growth in onion bulbs. The dormancy breaking effect of 1-MCP indicates a regulatory role of endogenous ethylene in onion bulb dormancy.

  12. Endogenous versus exogenous growth factor regulation of articular chondrocytes.

    Science.gov (United States)

    Shi, Shuiliang; Chan, Albert G; Mercer, Scott; Eckert, George J; Trippel, Stephen B

    2014-01-01

    Anabolic growth factors that regulate the function of articular chondrocytes are candidates for articular cartilage repair. Such factors may be delivered by pharmacotherapy in the form of exogenous proteins, or by gene therapy as endogenous proteins. It is unknown whether delivery method influences growth factor effectiveness in regulating articular chondrocyte reparative functions. We treated adult bovine articular chondrocytes with exogenous recombinant insulin-like growth factor-I (IGF-I) and transforming growth factor-beta1 (TGF-β1), or with the genes encoding these growth factors for endogenous production. Treatment effects were measured as change in chondrocyte DNA content, glycosaminoglycan production, and aggrecan gene expression. We found that IGF-I stimulated chondrocyte biosynthesis similarly when delivered by either exogenous or endogenous means. In contrast, exogenous TGF-β1 stimulated these reparative functions, while endogenous TGF-β1 had little effect. Endogenous TGF-β1 became more bioactive following activation of the transgene protein product. These data indicate that effective mechanisms of growth factor delivery for articular cartilage repair may differ for different growth factors. In the case of IGF-I, gene therapy or protein therapy appear to be viable options. In contrast, TGF-β1 gene therapy may be constrained by a limited ability of chondrocytes to convert latent complexes to an active form. Published 2013 by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. This article is a U.S. Government work and is in the public domain in the USA.

  13. Optimizing Multireservoir System Operating Policies Using Exogenous Hydrologic Variables

    Science.gov (United States)

    Pina, Jasson; Tilmant, Amaury; Côté, Pascal

    2017-11-01

    Stochastic dual dynamic programming (SDDP) is one of the few available algorithms to optimize the operating policies of large-scale hydropower systems. This paper presents a variant, called SDDPX, in which exogenous hydrologic variables, such as snow water equivalent and/or sea surface temperature, are included in the state space vector together with the traditional (endogenous) variables, i.e., past inflows. A reoptimization procedure is also proposed in which SDDPX-derived benefit-to-go functions are employed within a simulation carried out over the historical record of both the endogenous and exogenous hydrologic variables. In SDDPX, release policies are now a function of storages, past inflows, and relevant exogenous variables that potentially capture more complex hydrological processes than those found in traditional SDDP formulations. To illustrate the potential gain associated with the use of exogenous variables when operating a multireservoir system, the 3,137 MW hydropower system of Rio Tinto (RT) located in the Saguenay-Lac-St-Jean River Basin in Quebec (Canada) is used as a case study. The performance of the system is assessed for various combinations of hydrologic state variables, ranging from the simple lag-one autoregressive model to more complex formulations involving past inflows, snow water equivalent, and winter precipitation.

  14. Competition Between Endogenous and Exogenous Orienting of Visual Attention

    Science.gov (United States)

    Berger, Andrea; Henik, Avishai; Rafal, Robert

    2005-01-01

    The relation between reflexive and voluntary orienting of visual attention was investigated with 4 experiments: a simple detection task, a localization task, a saccade toward the target task, and a target identification task in which discrimination difficulty was manipulated. Endogenous and exogenous orienting cues were presented in each trial and…

  15. Lagrange-multiplier tests for weak exogeneity: a synthesis.

    NARCIS (Netherlands)

    Boswijk, H.P.; Urbain, J.P.

    1997-01-01

    This paper unifies two seemingly separate approaches to test weak exogeneity in dynamic regression models with Lagrange-multiplier statistics. The first class of tests focuses on the orthogonality between innovations and conditioning variables, and thus is related to the Durbin-Wu-Hausman

  16. Effects of exogenous human insulin dose adjustment on body mass ...

    African Journals Online (AJOL)

    glycaemic control by frequent exogenous insulin injections. To maintain fasting ... mass index in adult patients with type 1 diabetes mellitus at Kalafong Hospital ..... The Diabetes Control and Complications Trial cited in the review by Kaufman[2] also .... in obese insulin-resistant children: A randomized clinical trial. Diabetes ...

  17. Exogenous cycilc AMP and cycilc GMP influence the metabolism of ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-09-01

    Sep 1, 2009 ... well with the metabolic dynamics of exogenous 3H-glycerol within 30 h after injection. Moreover, ... low molecular weight that exist widely in organism and exhibit very ... endogenous tracers for the study of protein and lipid metabolism ..... DM (1998). SAAM ⁄: simulation, analysis, and modeling software for.

  18. Matching cue size and task properties in exogenous attention.

    Science.gov (United States)

    Burnett, Katherine E; d'Avossa, Giovanni; Sapir, Ayelet

    2013-01-01

    Exogenous attention is an involuntary, reflexive orienting response that results in enhanced processing at the attended location. The standard view is that this enhancement generalizes across visual properties of a stimulus. We test whether the size of an exogenous cue sets the attentional field and whether this leads to different effects on stimuli with different visual properties. In a dual task with a random-dot kinematogram (RDK) in each quadrant of the screen, participants discriminated the direction of moving dots in one RDK and localized one red dot. Precues were uninformative and consisted of either a large or a small luminance-change frame. The motion discrimination task showed attentional effects following both large and small exogenous cues. The red dot probe localization task showed attentional effects following a small cue, but not a large cue. Two additional experiments showed that the different effects on localization were not due to reduced spatial uncertainty or suppression of RDK dots in the surround. These results indicate that the effects of exogenous attention depend on the size of the cue and the properties of the task, suggesting the involvement of receptive fields with different sizes in different tasks. These attentional effects are likely to be driven by bottom-up mechanisms in early visual areas.

  19. The analgesic effects of exogenous melatonin in humans.

    Science.gov (United States)

    Andersen, Lars Peter Holst

    2016-10-01

    The hormone, melatonin is produced with circadian rhythm by the pineal gland in humans. The melatonin rhythm provides an endogenous synchronizer, modulating e.g. blood pressure, body temperature, cortisol rhythm, sleep-awake-cycle, immune function and anti-oxidative defence. Interestingly, a number of experimental animal studies demonstrate significant dose-dependent anti-nociceptive effects of exogenous melatonin. Similarly, recent experimental- and clinical studies in humans indicate significant analgesic effects. In study I, we systematically reviewed all randomized studies investigating clinical effects of perioperative melatonin. Meta-analyses demonstrated significant analgesic and anxiolytic effects of melatonin in surgical patients, equating reductions of 20 mm and 19 mm, respectively on a VAS, compared with placebo. Profound heterogeneity between the included studies was, however, present. In study II, we aimed to investigate the analgesic, anti-hyperalgesic and anti-inflammatory effects of exogenous melatonin in a validated human inflammatory pain model, the human burn model. The study was performed as a randomized, double blind placebo-controlled crossover study. Primary outcomes were pain during the burn injury and areas of secondary hyperalgesia. No significant effects of exogenous melatonin were observed with respect to primary or secondary outcomes, compared to placebo. Study III and IV estimated the pharmacokinetic variables of exogenous melatonin. Oral melatonin demonstrated a t max value of 41 minutes. Bioavailability of oral melatonin was only 3%. Elimination t 1/2 were approximately 45 minutes following both oral and intravenous administration, respectively. High-dose intravenous melatonin was not associated with increased sedation, in terms of simple reaction times, compared to placebo. Similarly, no other adverse effects were reported. In Study V, we aimed to re-analyse data obtained from a randomized analgesic drug trial by a selection of

  20. The selective electrochemical detection of homocysteine in the presence of glutathione, cysteine, and ascorbic acid using carbon electrodes.

    Science.gov (United States)

    Lee, P T; Lowinsohn, D; Compton, R G

    2014-08-07

    The detection of homocysteine, HCys, was achieved with the use of catechol via 1,4-Michael addition reaction using carbon electrodes: a glassy carbon electrode and a carbon nanotube modified glassy carbon electrode. The selective detection of homocysteine was investigated and achieved in the absence and presence of glutathione, cysteine and ascorbic acid using cyclic voltammetry and square wave voltammetry. A calibration curve of homocysteine detection was determined and the sensitivity is (0.20 ± 0.02) μA μM(-1) and the limit of detection is 660 nM within the linear range. Lastly, commercially available multi walled carbon nanotube screen printed electrodes were applied to the system for selective homocysteine detection. This work presents a potential practical application towards medical applications as it can be highly beneficial towards quality healthcare management.

  1. Synthesis of L-ascorbic acid in the phloem

    Directory of Open Access Journals (Sweden)

    Haupt Sophie

    2003-11-01

    Full Text Available Abstract Background Although plants are the main source of vitamin C in the human diet, we still have a limited understanding of how plants synthesise L-ascorbic acid (AsA and what regulates its concentration in different plant tissues. In particular, the enormous variability in the vitamin C content of storage organs from different plants remains unexplained. Possible sources of AsA in plant storage organs include in situ synthesis and long-distance transport of AsA synthesised in other tissues via the phloem. In this paper we examine a third possibility, that of synthesis within the phloem. Results We provide evidence for the presence of AsA in the phloem sap of a wide range of crop species using aphid stylectomy and histochemical approaches. The activity of almost all the enzymes of the primary AsA biosynthetic pathway were detected in phloem-rich vascular exudates from Cucurbita pepo fruits and AsA biosynthesis was demonstrated in isolated phloem strands from Apium graveolens petioles incubated with a range of precursors (D-glucose, D-mannose, L-galactose and L-galactono-1,4-lactone. Phloem uptake of D-[U-14C]mannose and L-[1-14C]galactose (intermediates of the AsA biosynthetic pathway as well as L-[1-14C]AsA and L-[1-14C]DHA, was observed in Nicotiana benthamiana leaf discs. Conclusions We present the novel finding that active AsA biosynthesis occurs in the phloem. This process must now be considered in the context of mechanisms implicated in whole plant AsA distribution. This work should provoke studies aimed at elucidation of the in vivo substrates for phloem AsA biosynthesis and its contribution to AsA accumulation in plant storage organs.

  2. How does exogenously applied cytokinin type affect growth and endogenous cytokinins in micropropagated Merwilla plumbea?

    Czech Academy of Sciences Publication Activity Database

    Aremu, A.O.; Plačková, Lenka; Bairu, M. W.; Novák, Ondřej; Plíhalová, Lucie; Doležal, Karel; Finnie, J. F.; van Staden, J.

    2014-01-01

    Roč. 118, č. 2 (2014), s. 245-256 ISSN 0167-6857 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Conservation * Medicinal plant * Micropropagation Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.125, year: 2014

  3. Oxidative Stress in The Hippocampus During Experimental Seizures Can Be Ameliorated With The Antioxidant Ascorbic Acid

    Directory of Open Access Journals (Sweden)

    Ítala Mônica Sales Santos

    2009-01-01

    Full Text Available Ascorbic acid has many nonenzymatic actions and is a powerful water-soluble antioxidant. It protects low density lipoproteins from oxidation and reduces harmful oxidants in the central nervous system. Pilocarpine-induced seizures have been suggested to be mediated by increases in oxidative stress. Current studies have suggested that antioxidant compounds may afford some level of neuroprotection against the neurotoxicity of seizures. The objective of the present study was to evaluate the neuroprotective effects of ascorbic acid (AA in rats, against the observed oxidative stress during seizures induced by pilocarpine. Wistar rats were treated with 0.9% saline (i.p., control group, ascorbic acid (500 mg/kg, i.p., AA group, pilocarpine (400 mg/kg, i.p., pilocarpine group, and the association of ascorbic acid (500 mg/kg, i.p. plus pilocarpine (400 mg/kg, i.p., 30 min before of administration of ascorbic acid (AA plus pilocarpine group. After the treatments all groups were observed for 6 h. The enzyme activities as well as the lipid peroxidation and nitrite concentrations were measured using spectrophotometric methods and the results compared to values obtained from saline and pilocarpine-treated animals. Protective effects of ascorbic acid were also evaluated on the same parameters. In pilocarpine group there was a significant increase in lipid peroxidation and nitrite level. However, no alteration was observed in superoxide dismutase and catalase activities. Antioxidant treatment significantly reduced the lipid peroxidation level and nitrite content as well as increased the superoxide dismutase and catalase activities in hippocampus of adult rats after seizures induced by pilocarpine. Our findings strongly support the hypothesis that oxidative stress in hippocampus occurs during seizures induced by pilocarpine, proving that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences, and also imply that a

  4. Ascorbic acid reduces noise-induced nitric oxide production in the guinea pig ear.

    Science.gov (United States)

    Heinrich, Ulf-Rüdiger; Fischer, Ilka; Brieger, Jürgen; Rümelin, Andreas; Schmidtmann, Irene; Li, Huige; Mann, Wolf J; Helling, Kai

    2008-05-01

    Noise-induced hearing loss can be caused, among other causes, by increased nitric oxide (NO) production in the inner ear leading to nitroactive stress and cell destruction. Some studies in the literature suggest that the degree of hearing loss (HL) could be reduced in an animal model through ascorbic acid supplementation. To identify the effect of ascorbic acid on tissue-dependent NO content in the inner ear of the guinea pig, we determined the local NO production in the organ of Corti and the lateral wall separately 6 hours after noise exposure. Prospective animal study in guinea pigs. Over a period of 7 days, male guinea pigs were supplied with minimum (25 mg/kg body weight/day) and maximum (525 mg/kg body weight/day) ascorbic acid doses, and afterwards exposed to noise (90 dB sound pressure level for 1 hour). The acoustic-evoked potentials were recorded before and after noise exposure. The organ of Corti and the lateral wall were incubated differently for 6 hours in culture medium, and the degree of NO production was determined by chemiluminescence. Ascorbic acid treatment reduced the hearing threshold shift after noise exposure depending on concentration. When the maximum ascorbic acid dose was substituted, NO production was significantly reduced in the lateral wall after noise exposure and slightly reduced in the organ of Corti. Oral supplementation of the natural radical scavenger ascorbic acid reduces the NO-production rate in the inner ear in noisy conditions. This finding supports the concept of inner ear protection by ascorbic acid supplementation.

  5. Ascorbic acid attenuates endothelial permeability triggered by cell-free hemoglobin.

    Science.gov (United States)

    Kuck, Jamie L; Bastarache, Julie A; Shaver, Ciara M; Fessel, Joshua P; Dikalov, Sergey I; May, James M; Ware, Lorraine B

    2018-01-01

    Increased endothelial permeability is central to shock and organ dysfunction in sepsis but therapeutics targeted to known mediators of increased endothelial permeability have been unsuccessful in patient studies. We previously reported that cell-free hemoglobin (CFH) is elevated in the majority of patients with sepsis and is associated with organ dysfunction, poor clinical outcomes and elevated markers of oxidant injury. Others have shown that Vitamin C (ascorbate) may have endothelial protective effects in sepsis. In this study, we tested the hypothesis that high levels of CFH, as seen in the circulation of patients with sepsis, disrupt endothelial barrier integrity. Human umbilical vein endothelial cells (HUVEC) were grown to confluence and treated with CFH with or without ascorbate. Monolayer permeability was measured by Electric Cell-substrate Impedance Sensing (ECIS) or transfer of 14 C-inulin. Viability was measured by trypan blue exclusion. Intracellular ascorbate was measured by HPLC. CFH increased permeability in a dose- and time-dependent manner with 1 mg/ml of CFH increasing inulin transfer by 50% without affecting cell viability. CFH (1 mg/ml) also caused a dramatic reduction in intracellular ascorbate in the same time frame (1.4 mM without CFH, 0.23 mM 18 h after 1 mg/ml CFH, p < 0.05). Pre-treatment of HUVECs with ascorbate attenuated CFH induced permeability. CFH increases endothelial permeability in part through depletion of intracellular ascorbate. Supplementation of ascorbate can attenuate increases in permeability mediated by CFH suggesting a possible therapeutic approach in sepsis. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. H2O2 mediates ALA-induced glutathione and ascorbate accumulation in the perception and resistance to oxidative stress in Solanum lycopersicum at low temperatures.

    Science.gov (United States)

    Liu, Tao; Hu, Xiaohui; Zhang, Jiao; Zhang, Junheng; Du, Qingjie; Li, Jianming

    2018-02-15

    Low temperature is a crucial factor influencing plant growth and development. The chlorophyll precursor, 5-aminolevulinic acid (ALA) is widely used to improve plant cold tolerance. However, the interaction between H 2 O 2 and cellular redox signaling involved in ALA-induced resistance to low temperature stress in plants remains largely unknown. Here, the roles of ALA in perceiving and regulating low temperature-induced oxidative stress in tomato plants, together with the roles of H 2 O 2 and cellular redox states, were characterized. Low concentrations (10-25 mg·L - 1 ) of ALA enhanced low temperature-induced oxidative stress tolerance of tomato seedlings. The most effective concentration was 25 mg·L - 1 , which markedly increased the ratio of reduced glutathione and ascorbate (GSH and AsA), and enhanced the activities of superoxide dismutase, catalase, ascorbate peroxidase, dehydroascorbate reductase, and glutathione reductase. Furthermore, gene expression of respiratory burst oxidase homolog1 and H 2 O 2 content were upregulated with ALA treatment under normal conditions. Treatment with exogenous H 2 O 2 , GSH, and AsA also induced plant tolerance to oxidative stress at low temperatures, while inhibition of GSH and AsA syntheses significantly decreased H 2 O 2 -induced oxidative stress tolerance. Meanwhile, scavenging or inhibition of H 2 O 2 production weakened, but did not eliminate, GSH- or AsA- induced tomato plant tolerance to oxidative stress at low temperatures. Appropriate concentrations of ALA alleviated the low temperature-induced oxidative stress in tomato plants via an antioxidant system. The most effective concentration was 25 mg·L - 1 . The results showed that H 2 O 2 induced by exogenous ALA under normal conditions is crucial and may be the initial step for perception and signaling transmission, which then improves the ratio of GSH and AsA. GSH and AsA may then interact with H 2 O 2 signaling, resulting in enhanced antioxidant capacity

  7. Novel Spectrophotometric Methods for Determination of Salicylamide and Ascorbic acid in their binary mixture

    International Nuclear Information System (INIS)

    Ali, N.W.; Zaazaa, H.E.S.; Abdelrahman, M.M.

    2014-01-01

    Simple, selective and precise four spectrophotometric methods were developed and validated for quantitative determination of Salicylamide (SAD) and Ascorbic acid (ASC, Vitamin C) in their binary mixture. Method A is Area under curve spectrophotometry, in which the area under curve in the wavelength ranges 225-245 nm and 265-285 nm were selected for determination of SAD and ASC. Method B is based on dual wavelength spectrophotometry, where ASC can be determined by difference in absorbance at 249.8 and 285.8 nm. On the same way; SAD is measured by difference in absorbance at 240.4 and 286.4 nm. Method C utilizes isoabsorptive point spectrophotometry where total concentration of SAD and ASC was calculated at their isoabsorptive points at 246.4 and 287 nm, while SAD concentration alone can be determined by first derivative spectrophotometry (1D) at 315.4 nm, then ASC concentration can be determined by subtraction. Method D is ratio subtraction spectrophotometry, where ASC can be determined by dividing the spectrum of the mixture by the spectrum of the SAD (as a divisor) followed by subtracting the constant absorbance value of the plateau region, then finally multiplying the obtained spectrum by the spectrum of the divisor. The developed methods have been successfully applied for determination of the studied drugs in different laboratory prepared mixtures and in their pharmaceutical formulation. Statistical comparison between the results obtained by applying the proposed methods and the reported HPLC method was done, and it was found that there was no significant difference between them regarding both accuracy and precision. (author)

  8. L-Ascorbic acid metabolism during fruit development in an ascorbate-rich fruit crop chestnut rose (Rosa roxburghii Tratt).

    Science.gov (United States)

    Huang, Ming; Xu, Qiang; Deng, Xiu-Xin

    2014-09-01

    Chestnut rose (Rosa roxburghii Tratt) is a fruit crop that contains unusually high levels of l-ascorbic acid (AsA; ∼1300 mg 100g(-1) FW). To explore the mechanisms underlying AsA metabolism, we investigated the distribution and abundance of AsA during fruit development. We also analyzed gene expression patterns, enzyme activities, and content of metabolites related to AsA biosynthesis and recycling. AsA first accumulated during late fruit development and continued to accumulate during ripening, with the highest accumulation rate near fruit maturity. The redox state of AsA in fruit was also enhanced during late fruit development, while leaf and other tissues had much lower levels of AsA and the redox state of AsA was lower. In mature fruit, AsA was mainly distributed in the cytoplasm of the mesocarp. Correlation analysis suggested that the gene expression patterns, enzyme activities, and related metabolite concentrations involved in the l-galactose pathway showed relatively high correlations with the accumulation rate of AsA. The gene expression pattern and activity of dehydroascorbate reductase (DHAR, EC 1.8.5.1) correlated strongly with AsA concentration, possibly indicating the crucial role of DHAR in the accumulation of high levels of AsA in chestnut rose fruit. Over expression of DHAR in Arabidopsis significantly increased the reduced AsA content and redox state. This was more effective than over expression of the l-galactose pathway gene GDP-d-mannose-3,5-epimerase (EC 5.1.3.18). These findings will enhance understanding of the molecular mechanisms regulating accumulation of AsA in chestnut rose. Copyright © 2014 Elsevier GmbH. All rights reserved.

  9. Thermal degradation kinetics of ascorbic acid, thiamine and riboflavin in rosehip (Rosa canina L nectar

    Directory of Open Access Journals (Sweden)

    Çetin KADAKAL

    2017-10-01

    Full Text Available Abstract In this paper, the loss of L-ascorbic acid, thiamine and riboflavin in rosehip nectar with the heating periods (0, 5, 10, 15, 20 and 30 min at temperatures ranging from 70 to 95 °C is analyzed and experimental results are presented. Firstly, dried rosehip fruits were processed to rosehip nectar and then thermal treatment is performed. Liquid chromatographic (HPLC method was used for the analysis of the contents of L-ascorbic acid, thiamine and riboflavin and examined compounds are thoroughly separated within 25 min. During thermal processing, degradation of L-ascorbic acid, thiamine and riboflavin in rosehip nectar were fitted to a first-order reaction kinetic model. Arrhenius relationship was used for the description of temperature dependence of reaction. Activation energies for L-ascorbic acid, thiamine and riboflavin between 70 to 95 ºC were found to be 55.30, 36.38 and 37.15 kJ/mol, respectively. To the best of the author’s knowledge, due to lack of study on the thermal degradation of L-ascorbic acid, thiamine and riboflavin in rosehip nectar, this manuscript will be the first reported study to enable future analysis.

  10. Effect of sodium ascorbate and sodium nitrite on protein and lipid oxidation in dry fermented sausages.

    Science.gov (United States)

    Berardo, A; De Maere, H; Stavropoulou, D A; Rysman, T; Leroy, F; De Smet, S

    2016-11-01

    The effects of sodium nitrite and ascorbate on lipid and protein oxidation were studied during the ripening process of dry fermented sausages. Samples were taken at day 0, 2, 8, 14, 21 and 28 of ripening to assess lipid (malondialdehyde) and protein (carbonyls and sulfhydryl groups) oxidation. Sodium ascorbate and nitrite were separately able to reduce the formation of malondialdehyde. Their combined addition resulted in higher amounts of carbonyl compounds compared to their separate addition or the treatment without any of both compounds. Moreover, sodium nitrite limited the formation of γ-glutamic semialdehyde whereas sodium ascorbate showed a pro-oxidant effect. A loss of thiol groups was observed during ripening, which was not affected by the use of sodium ascorbate nor sodium nitrite. In conclusion, sodium nitrite and ascorbate affected protein and lipid oxidation in different manners. The possible pro-oxidant effect of their combined addition on carbonyl formation might influence the technological and sensory properties of these products. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Methemoglobinemia and ascorbate deficiency in hemoglobin E β thalassemia: metabolic and clinical implications

    Science.gov (United States)

    Allen, Angela; Fisher, Christopher; Premawardhena, Anuja; Bandara, Dayananda; Perera, Ashok; Allen, Stephen; St Pierre, Timothy; Olivieri, Nancy

    2012-01-01

    During investigations of the phenotypic diversity of hemoglobin (Hb) E β thalassemia, a patient was encountered with persistently high levels of methemoglobin associated with a left-shift in the oxygen dissociation curve, profound ascorbate deficiency, and clinical features of scurvy; these abnormalities were corrected by treatment with vitamin C. Studies of erythropoietin production before and after treatment suggested that, as in an ascorbate-deficient murine model, the human hypoxia induction factor pathway is not totally dependent on ascorbate levels. A follow-up study of 45 patients with HbE β thalassemia showed that methemoglobin levels were significantly increased and that there was also a significant reduction in plasma ascorbate levels. Haptoglobin levels were significantly reduced, and the high frequency of the 2.2 haptoglobin genotype may place an additional pressure on ascorbate as a free-radical scavenger in this population. There was, in addition, a highly significant correlation between methemoglobin levels, splenectomy, and factors that modify the degree of globin-chain imbalance. Because methemoglobin levels are modified by several mechanisms and may play a role in both adaptation to anemia and vascular damage, there is a strong case for its further study in other forms of thalassemia and sickle-cell anemia, particularly when splenic function is defective. PMID:22885163

  12. Electrochemical oxidation of ascorbic acid mediated by carbon nano tubes/ Li+/ carbon paste modified solid electrode

    International Nuclear Information System (INIS)

    Goh, J.K.; Tan, W.T.

    2008-01-01

    Multi-walled carbon nano tube (MWCNT) was used to modify BPPG electrode because of its unique structure and extraordinary properties. MWCNT modified electrode exhibited obvious enhancing and electro catalyzing effects to the oxidation of ascorbic acid using cyclic voltammetry technique. MWCNT was bonded on BPPG electrode surface using carbon paste with ratio of 30 % (w/ W) carbon paste (binder): 70 % (w/ w) MWCNT. This method of modification has lowered the capacitance background current and enabled lower detection limit of ascorbic acid concentration. The electrical conductivity property of MWCNT modified electrode was further improved with the intercalation with lithium ion and resulted in current enhancement of 2 times on the oxidation current of ascorbic acid. Parameters of pH and temperature showed significant relation to the sensitivity of MWCNT modified electrode. Under the optimized parameters, the calibration curve constructed was linear up from 50 μM to 5 mM with sensitivity of 34.5 mA M -1 . The practical application of MWCNT modified electrode was demonstrated with Vitamin C pill and orange juice. Good reproducibility and recovery of ascorbic acid concentration showed the feasibility of MWCNT modified electrode to be used in the detection of ascorbic acid in aqueous solution. This also proposed MWCNT modified BPPG electrode possessed advantages such as low detection limit, high stability, low cost and simplicity in fabrication. (author)

  13. Arsenic-induced toxicity and the protective role of ascorbic acid in mouse testis

    International Nuclear Information System (INIS)

    Chang, Soo Im; Jin, Bohwan; Youn, Pilju; Park, Changbo; Park, Jung-Duck; Ryu, Doug-Young

    2007-01-01

    Oxidative stress has been suggested to be a major cause of male reproductive failure. Here, we investigated whether arsenic, which impairs male reproductive functions in rodent models, acts by inducing oxidative stress. Male 8-week-old ICR mice were given drinking water containing 20 or 40 mg/l sodium arsenite with or without 0.75 or 1.5 g/l of the antioxidant ascorbic acid for 5 weeks. The arsenic-treated mice showed decreased epididymidal sperm counts and testicular weights compared to untreated mice. These effects were reversed in mice that were co-treated with ascorbic acid. Similarly, arsenic treatment lowered the activities of testicular 3β-hydroxysteroid dehydrogenase (HSD) and 17β-HSD, which play important roles in steroidogenesis, and this was reversed by co-treatment with ascorbic acid. The testicles of arsenic-treated mice had decreased glutathione (GSH) levels (which correlate inversely with the degree of cellular oxidative stress) and elevated levels of protein carbonyl (a marker of oxidative damage to tissue proteins). Ascorbic acid co-treatment reversed both of these effects. Thus, ascorbic acid blocks both the adverse effects of arsenic on male reproductive functions and the arsenic-induced testicular oxidative changes. These observations support the notion that arsenic impairs male reproductive function by inducing oxidative stress

  14. Ascorbic acid glycation of lens proteins produces UVA sensitizers similar to those in human lens

    International Nuclear Information System (INIS)

    Ortwerth, B.J.; Linetsky, Mikhail; Olesen, P.R.

    1995-01-01

    Soluble calf lens proteins were extensively glycated during a 4 week incubation with ascorbic acid in the presence of oxygen. Amino acids analysis of the dialyzed proteins removed at weekly intervals showed an increasing loss of lysine, arginine and histidine, consistent with the extensive protein cross-linking observed. Irradiation of the dialyzed samples with UVA light (1.0 kJ/cm 2 total illumination through a 338 nm cutoff filter) caused an increasing loss of tryptophan, an additional loss of histidine and the production of micromolar concentrations of hydrogen peroxide. No alteration in amino acid content and no photolytic effects were seen in proteins incubated without ascorbic acid in proteins incubated with glucose for 4 weeks. The rate of hydrogen peroxide formation was linear with each glycated sample with a maximum production of 25 nmol/mg protein illuminated. The possibility that the sensitizer activity was due to an ascorbate-induced oxidation of tryptophan was eliminated by the presence of a heavy metal ion chelator during the incubation and by showing equivalent effects with ascorbate-incubated ribonuclease A, which is devoid of tryptophan. The ascorbate-incubated samples displayed increasing absorbance at wavelengths above 300 nm and increasing fluorescence (340/430) as glycation proceeded. The spectra of the 4 week glycated proteins were identical to those obtained with a solubilized water-insoluble fraction from human lens, which is known to have UVA sensitizer activity. (Author)

  15. Ascorbic acid reduced mutagenicity at the HPRT locus in CHO cells against thermal neutron radiation

    International Nuclear Information System (INIS)

    Kinashi, Yuko; Sakurai, Yoshinori; Masunaga, Shinichiro; Suzuki, Minoru; Nagata, Kenji; Ono, Koji

    2004-01-01

    We investigated the biological effects of the long-lived radicals induced following neutron irradiation. It has been reported that radiation-induced long-lived radicals were scavenged by post-irradiation treatment of ascorbic acid (Koyama, 1998). We studied the effects of ascorbic acid acting as a long-lived radical scavenger on cell killing and mutagenicity in Chinese hamster ovary cells against thermal neutrons produced at the Kyoto University Research reactor. Ascorbic acid was added to cells 30 min after neutron irradiation and removed 150 min after irradiation. The biological end point of cell survival was measured by colony formation assay. The mutagenicity was measured by the mutant frequency in the HPRT locus. The post-irradiation treatment of ascorbic acid did not alter the cell killing effect of neutron radiation. However, the mutagenicity was decreased, especially when the cells were irradiated with boron. Our results suggested that ascorbic acid scavenged long-lived radicals effectively and caused apparent protective effects against mutagenicity of boron neutron capture therapy

  16. Dietary taurine alters ascorbic acid metabolism in rats fed diets containing polychlorinated biphenyls.

    Science.gov (United States)

    Mochizuki, H; Oda, H; Yokogoshi, H

    2000-04-01

    The effect of dietary taurine on ascorbic acid metabolism and hepatic drug-metabolizing enzymes was investigated in rats fed diets containing polychlorinated biphenyls (PCB) to determine whether taurine has an adaptive and protective function in xenobiotic-treated animals. Young male Wistar rats (60 g) were fed diets containing 0 or 0.2 g/kg diet PCB with or without 30 g/kg diet of taurine for 14 d. The rats fed the PCB-containing diets had greater liver weight, higher ascorbic acid concentrations in the liver and spleen and greater hepatic cytochrome P-450 contents than control rats that were not treated with PCB (P ascorbic acid excretion was enhanced, and serum cholesterol concentration (especially HDL-cholesterol) was significantly elevated compared with those in control rats. Dietary taurine significantly potentiated the increases in the urinary excretion of ascorbic acid and the rise in the levels of cytochrome P-450 which were caused by PCB treatment. On the other hand, the supplementation of taurine to control diet did not alter these variables. Taurine may enhance the hepatic drug-metabolizing systems, leading to the stimulation of the ascorbic acid metabolism in rats fed diets containing PCB.

  17. Further investigations on the role of ascorbic acid in stratum corneum lipid models after UV exposure.

    Science.gov (United States)

    Trommer, Hagen; Böttcher, Rolf; Huschka, Christoph; Wohlrab, Wolfgang; Neubert, Reinhard H H

    2005-08-01

    This study is the continuation of our research into vitamin C and its possible effects on human skin after topical administration. The effects of ascorbic acid, iron ions and UV irradiation on stratum corneum lipid models were investigated. The lipid models used were: a simple system (linolenic acid dispersion), a complex system (liposomes consisting of dipalmitoylphosphatidylcholine, cholesterol and linolenic acid) and complex systems with additionally incorporated ceramides (types III and IV). The lipid peroxidation was quantified by the thiobarbituric acid assay. A human adult low-calcium high-temperature (HaCaT) keratinocytes cell culture was used as a second in-vitro model. The amount of intracellular peroxides was determined by measuring the fluorescence intensity using the dihydrorhodamine 123 assay. Electron paramagnetic resonance spectroscopy was used to study the influence of ascorbic acid and iron ions on the signal intensity of 5-doxylstearic acid during UV exposure. Ascorbic acid showed prooxidative properties in the thiobarbituric acid assay whereas cell protection was measured in the HaCaT keratinocytes experiments. Electron paramagnetic resonance investigations revealed different extents of free radical production generated by iron ions, ascorbic acid and UV irradiation. In evaluating the results from this study new aspects of the mechanism of lipid damage caused by these three factors were suggested, transcending the simple redox behaviour of ascorbic acid.

  18. Oxidation in fish oil enriched mayonnaise : Ascorbic acid and low pH increase oxidative deterioration

    DEFF Research Database (Denmark)

    Jacobsen, Charlotte; Timm Heinrich, Maike; Meyer, Anne S.

    2001-01-01

    The effect of ascorbic acid (0-4000 ppm) and pH (3.8-6.2) on oxidation and levels of iron and copper in various fractions of mayonnaise enriched with 16% fish oil was investigated. Ascorbic acid induced release of iron from the assumed oil- water interface into the aqueous phase at all pH levels......, but this effect of ascorbic acid was strongest at low pH (pH 3.8- 4.2). Ascorbic acid generally promoted formation of volatile oxidation compounds and reduced the peroxide value in mayonnaises. Peroxide values and total volatiles generally increased with decreasing pH values, suggesting that low pH promoted...... oxidation. It is proposed that iron bridges between the egg yolk proteins low-density lipoproteins, lipovitellin, and phosvitin at the oil-water interface are broken at low pH values, whereby iron ions become accessible as oxidation initiators. In the presence of ascorbic acid, oxidation is further enhanced...

  19. Static magnetic field reduced exogenous oligonucleotide uptake by spermatozoa using magnetic nanoparticle gene delivery system

    Science.gov (United States)

    Katebi, Samira; Esmaeili, Abolghasem; Ghaedi, Kamran

    2016-03-01

    Spermatozoa could introduce exogenous oligonucleotides of interest to the oocyte. The most important reason of low efficiency of sperm mediated gene transfer (SMGT) is low uptake of exogenous DNA by spermatozoa. The aim of this study was to evaluate the effects of static magnetic field on exogenous oligonucleotide uptake of spermatozoa using magnetofection method. Magnetic nanoparticles (MNPs) associated with the labeled oligonucleotides were used to increase the efficiency of exogenous oligonucleotide uptake by rooster spermatozoa. We used high-field/high-gradient magnet (NdFeB) to enhance and accelerate exogenous DNA sedimentation at the spermatozoa surface. Flow cytometry analysis was performed to measure viability and percentage of exogenous oligonucleotide uptake by sperm. Flow cytometry analysis showed a significant increase in exogenous oligonucleotide uptake by rooster spermatozoa (Prooster spermatozoa; however unlike others studies, static magnetic field, was not only ineffective to enhance exogenous oligonucleotide uptake by rooster spermatozoa but also led to reduction in efficiency of magnetic nanoparticles in gene transfer.

  20. Treatment with exogenous surfactant stimulates endogenous surfactant synthesis in premature infants with respiratory distress syndrome

    NARCIS (Netherlands)

    Bunt, JEH; Carnielli, VP; Janssen, DJ; Wattimena, JLD; Hop, WC; Sauer, PJ; Zimmermann, LJI

    2000-01-01

    Objective: Treatment of preterm infants with respiratory distress syndrome (RDS) with exogenous surfactant has greatly improved clinical outcome. Some infants require multiple doses, and it has not been studied whether these large amounts of exogenous surfactant disturb endogenous surfactant

  1. Role of Endogenous and Exogenous Tocopherols in the Lipid Stability of Marine Oil Systems: A Review

    Directory of Open Access Journals (Sweden)

    Guadalupe Miroslava Suárez-Jiménez

    2016-11-01

    Full Text Available In marine organisms primarily intended for human consumption, the quality of the muscle and the extracted oils may be affected by lipid oxidation during storage, even at low temperatures. This has led to a search for alternatives to maintain quality. In this sense, antioxidant compounds have been used to prevent such lipid deterioration. Among the most used compounds are tocopherols, which, due to their natural origin, have become an excellent alternative to prevent or retard lipid oxidation and maintain the quality of marine products. Tocopherols as antioxidants have been studied both exogenously and endogenously. Exogenous tocopherols are often used by incorporating them into plastic packaging films or adding them directly to fish oil. It has been observed that exogenous tocopherols incorporated in low concentrations maintain the quality of both muscle and the extracted oils during food storage. However, it has been reported that tocopherols applied at higher concentrations act as a prooxidant molecule, probably because their reactions with singlet oxygen may generate free radicals and cause the oxidation of polyunsaturated fatty acids in fish oils. However, when tocopherols are included in a fish diet (endogenous tocopherols, the antioxidant effect on the muscle lipids is more effective due to their incorporation into the membrane lipids, which can help extend the shelf life of seafood by reducing the lipid deterioration that occurs due to antioxidant synergy with other phenolic compounds used supplements in fish muscle. This review focuses on the most important studies in this field and highlights the potential of using tocopherols as antioxidants in marine oils.

  2. A taxonomy of endogenous and exogenous uncertainty in high-risk, high-impact contexts.

    Science.gov (United States)

    Alison, Laurence; Power, Nicola; van den Heuvel, Claudia; Waring, Sara

    2015-07-01

    By reference to a live hostage negotiation exercise, this study presents a taxonomy of uncertainty that can be usefully applied to assist in the categorization and application of findings from decision-making research conducted in naturalistic (specifically critical incident) settings. Uncertainty was measured via observational methods (during the exercise and by reference to video footage), decision logs, and postincident simulated recall interviews with trainee police officers. Transcripts were coded and analyzed thematically. Uncertainty was dichotomized as deriving from either endogenous sources (about the problem situation itself) or exogenous sources (about the operating system that is dealing with the incident). Overall, exogenous uncertainty (75%) was more prevalent than endogenous uncertainty (25%), specifically during discussions on plan formulation and execution. It was also qualitatively associated with poor role understanding and trust. Endogenous uncertainty was more prevalent during discussions on situation assessment and plan formulation. The taxonomy provides a useful way for organizational researchers to categorize uncertainty during the naturalistic observations of workplace interactions and decision making. It reduces the complexity associated with observational research to allow organizational psychologists to better tailor their recommendations for reducing uncertainty. Dealing with endogenous uncertainties would entail targeting decision making specific to the problem incident (e.g., introduce training or policy to reduce redundant fixation on rote-repetitive superordinate goals and focus on more short-term actionable goals during situation assessments). Dealing with exogenous uncertainties would entail improving decision making relating to management and team processes across critical incidents (e.g., training to clarify distributed roles in critical incident teams to aid plan formulation and execution). Organizational researchers interested

  3. Role of Endogenous and Exogenous Tocopherols in the Lipid Stability of Marine Oil Systems: A Review

    Science.gov (United States)

    Suárez-Jiménez, Guadalupe Miroslava; López-Saiz, Carmen María; Ramírez-Guerra, Hugo Enrique; Ezquerra-Brauer, Josafat Marina; Ruiz-Cruz, Saul; Torres-Arreola, Wilfrido

    2016-01-01

    In marine organisms primarily intended for human consumption, the quality of the muscle and the extracted oils may be affected by lipid oxidation during storage, even at low temperatures. This has led to a search for alternatives to maintain quality. In this sense, antioxidant compounds have been used to prevent such lipid deterioration. Among the most used compounds are tocopherols, which, due to their natural origin, have become an excellent alternative to prevent or retard lipid oxidation and maintain the quality of marine products. Tocopherols as antioxidants have been studied both exogenously and endogenously. Exogenous tocopherols are often used by incorporating them into plastic packaging films or adding them directly to fish oil. It has been observed that exogenous tocopherols incorporated in low concentrations maintain the quality of both muscle and the extracted oils during food storage. However, it has been reported that tocopherols applied at higher concentrations act as a prooxidant molecule, probably because their reactions with singlet oxygen may generate free radicals and cause the oxidation of polyunsaturated fatty acids in fish oils. However, when tocopherols are included in a fish diet (endogenous tocopherols), the antioxidant effect on the muscle lipids is more effective due to their incorporation into the membrane lipids, which can help extend the shelf life of seafood by reducing the lipid deterioration that occurs due to antioxidant synergy with other phenolic compounds used supplements in fish muscle. This review focuses on the most important studies in this field and highlights the potential of using tocopherols as antioxidants in marine oils. PMID:27886145

  4. Ascorbate availability affects tumor implantation-take rate and increases tumor rejection in Gulo–/– mice

    Directory of Open Access Journals (Sweden)

    Campbell EJ

    2016-04-01

    Full Text Available Elizabeth J Campbell,1 Margreet CM Vissers,2 Gabi U Dachs1 1Mackenzie Cancer Research Group, 2Centre for Free Radical Research, Department of Pathology, University of Otago, Christchurch, New Zealand Abstract: In solid tumors, HIF1 upregulates the expression of hundreds of genes involved in cell survival, tumor growth, and adaptation to the hypoxic microenvironment. HIF1 stabilization and activity are suppressed by prolyl and asparagine hydroxylases, which require oxygen as a substrate and ascorbate as a cofactor. This has led us to hypothesize that intracellular ascorbate availability could modify the hypoxic HIF1 response and influence tumor growth. In this study, we investigated the effect of variable intracellular ascorbate levels on HIF1 induction in cancer cells in vitro, and on tumor-take rate and growth in the Gulo–/– mouse. These mice depend on dietary ascorbate, and were supplemented with 3,300 mg/L, 330 mg/L, or 33 mg/L ascorbate in their drinking water, resulting in saturating, medium, or low plasma and tissue ascorbate levels, respectively. In Lewis lung carcinoma cells (LL/2 in culture, optimal ascorbate supplementation reduced HIF1 accumulation under physiological but not pathological hypoxia. LL/2, B16-F10 melanoma, or CMT-93 colorectal cancer cells were implanted subcutaneously into Gulo–/– mice at a range of cell inocula. Establishment of B16-F10 tumors in mice supplemented with 3,300 mg/L ascorbate required an increased number of cancer cells to initiate tumor growth compared with the number of cells required in mice on suboptimal ascorbate intake. Elevated ascorbate intake was also associated with decreased tumor ascorbate levels and a reduction in HIF1α expression and transcriptional activity. Following initial growth, all CMT-93 tumors regressed spontaneously, but mice supplemented with 33 mg/L ascorbate had lower plasma ascorbate levels and grew larger tumors than optimally supplemented mice. The data from this

  5. Fate of exogenously supplied bacterial DNA in soybean

    Energy Technology Data Exchange (ETDEWEB)

    Ndiku, Luyindula [Commissariat des Sciences Nucleaires, Kinshasa (Zaire). Centre Regional d' Etudes Nucleaires

    1980-01-01

    The fate of exogenously supplied radiolabelled DNA from agrobacterium tumefaciens and micrococcus lysodeikticus was investigated in soybean tissues growing under various physiological conditions. The following observations are made: (a) Rapid degradation and reutilization of the donor DNA was observed in callus tissue culture. (b) Germinating seeds and five-day old seedlings were shown to degrade DNA in the incubation medium and to ultilize these degradation products for their own DNA synthesis. Reutilization could be almost totally suppressed the addition of unlabelled thymidine as a competitor. This allowed a detection of significant amounts of residuel donor closely but transiently associated with the plant tissues. (c) In soybean shoots dipped into a solution of donor DNA, partly this DNA was found to first migrate to the leaves where mostly labelled endogenous DNA was later found. Very large amounts of polymerized exogenous DNA were found in the regenerated roots after 12 days of culture.

  6. On the fate of exogenously supplied bacterial DNA in soybean

    International Nuclear Information System (INIS)

    Luyindula Ndiku

    1980-01-01

    The fate of exogenously supplied radiolabelled DNA from agrobacterium tumefaciens and micrococcus lysodeikticus was investigated in soybean tissues growing under various physiological conditions. The following observations are made: a) Rapid degradation and reutilization of the donor DNA was observed in callus tissue culture. b) Germinating seeds and five-day old seedlings were shown to degrade DNA in the incubation medium and to ultilize these degradation products for their own DNA synthesis. Reutilization could be almost totally suppressed the addition of unlabelled thymidine as a competitor. This allowed a detection of significant amounts of residuel donor closely but transiently associated with the plant tissues. c) In soybean shoots dipped into a solution of donor DNA, partly this DNA was found to first migrate to the leaves where mostly labelled endogenous DNA was later found. Very large amounts of polymerized exogenous DNA were found in the regenerated roots after 12 days of culture. (author)

  7. Exogenous factors in panic disorder: clinical and research implications.

    Science.gov (United States)

    Roy-Byrne, P P; Uhde, T W

    1988-02-01

    Because panic disorder has an underlying biologic and probably genetic basis, the role of factors outside the organism in initiating and sustaining panic is often overlooked. The authors review certain exogenous factors that seem capable of triggering attacks and/or increasing their frequency and intensity: self-administered pharmacologic agents (caffeine, alcohol, nicotine, over-the-counter cold preparations, cannabis, cocaine); habits (sleep deprivation, diet, exercise, relaxation, hyperventilation); and aspects of the environment (fluorescent lighting, life stressors). There may be a specificity to the action of some of these factors, because certain factors previously thought to trigger panic attacks (e.g., pain, hypoglycemia) have been proved not to have this effect. Although the clinical significance of many of the exogenous factors discussed still awaits empirical confirmation, attention to such factors during the initial evaluation of a patient with panic disorder may be helpful in formulating a successful treatment plan.

  8. Analyzing Bullwhip Effect in Supply Networks under Exogenous Uncertainty

    Directory of Open Access Journals (Sweden)

    Mitra Darvish

    2014-05-01

    Full Text Available This paper explains a model for analyzing and measuring the propagation of order amplifications (i.e. bullwhip effect for a single-product supply network topology considering exogenous uncertainty and linear and time-invariant inventory management policies for network entities. The stream of orders placed by each entity of the network is characterized assuming customer demand is ergodic. In fact, we propose an exact formula in order to measure the bullwhip effect in the addressed supply network topology considering the system in Markovian chain framework and presenting a matrix of network member relationships and relevant order sequences. The formula turns out using a mathematical method called frequency domain analysis. The major contribution of this paper is analyzing the bullwhip effect considering exogenous uncertainty in supply networks and using the Fourier transform in order to simplify the relevant calculations. We present a number of numerical examples to assess the analytical results accuracy in quantifying the bullwhip effect.

  9. Theory of endogenous and exogenous motivation in L2 migration

    Directory of Open Access Journals (Sweden)

    Kambon, Obadele Bakari

    2015-09-01

    Full Text Available Implied in theories of Second Language Acquisition (SLA is the notion that language learning is analogous to obtaining or acquiring a possession – thus the use of the term ‘acquisition.’ While this interpretation has gone relatively unchallenged in the literature, this article introduces a new analogy whereby language learning is seen as analogous to a process of permanent or semi-permanent migration towards a new socio-linguistic L2 space. As such, a theory of endogenous and exogenous motivation is delineated, entailing a dynamic interplay between internal (primarily psychological and external (primarily sociological push-pull factors. Endogenous and exogenous push-pull factors, together with various other personal factors, contribute to learner decisions to migrate towards, move away from or remain inert with regard to the target language. Further, motivation is framed in the larger theoretical context of causation.

  10. Exogenous cellulases of thermophilic micromycetes. Pt. 1. Selection of producers

    Energy Technology Data Exchange (ETDEWEB)

    Kvesitadze, G; Kvachadze, L; Aleksidze, T; Chartishvili, D K

    1986-01-01

    More than 600 micromycetes - representatives of different genera have been investigated for their ability to produce exogenous cellulases. Most of the investigated cultures were found to produce these enzymes, 24 cultures being thermophilic, and 18 thermotolerant. Cellulase or its derivatives proved to be the most favourable carbon source for cellulase secretion. None of the thermophilic cultures studied manifested the ability of exogenous exoglucanase biosynthesis. Using UV-rays as mutagen, a mutant strain A. terreus T-49 has been obtained being characterized by an increased endo-glucanase and cellobiase activity, as compared to the initial strains. The cellulase preparations of thermophilic micromycetes contain one cellulasic component: endo-glucanase, or two: endo-glucanase and cellobiase.

  11. Exogenous and endogenous shifts of attention in perihand space.

    Science.gov (United States)

    Le Bigot, Nathalie; Grosjean, Marc

    2016-07-01

    While some studies have found that attentional orienting is altered in perihand space, most have not. One reason for such discrepancies may be related to the types of cues (uninformative and informative) that have been used, as they are known to induce different types of shifts of attention (exogenous and endogenous, respectively). To systematically address this question, two experiments were performed in which an uninformative peripheral cue (Experiment 1) or an informative central cue (Experiment 2) preceded a peripheral target with a short (100-150 ms) stimulus-onset asynchrony. Participants performed the task with their left hand, right hand, both hands, or no hands near the display. Cueing effects were obtained in both experiments, but they were only modulated by hand position in Experiment 1, with larger effects observed in the right- and both-hand conditions. These findings suggest that exogenous attention shifts are affected by hand proximity, while endogenous shifts are not.

  12. Differentiation of stem cells upon deprivation of exogenous FGF2

    DEFF Research Database (Denmark)

    Kjartansdóttir, Kristín Rós; Gabrielsen, Anette; Reda, Ahmed

    2012-01-01

    Establishing a model for in vitro differentiation of human embryonic stem cells (hESCs) towards the germ cell lineage could be used to identify molecular mechanisms behind germ cell differentiation that may help in understanding human infertility. Here, we evaluate whether a lack of exogenous...... fibroblast growth factor 2 (FGF2) is supporting spontaneous differentiation of hESCs cultured on human foreskin fibroblast (hFF) monolayers towards germ cell lineage. Additionally to depriving the hESCs of exogenous FGF2, cells were stimulated with all-trans retinoic acid (ATRA). To get a more comprehensive...... impression on effects of removal of FGF2 and stimulation with ATRA, we combined the results of three cell lines for each experimental setting. When combining gene expression profiles of three cell lines for 96 genes, only 6 genes showed a significant up-regulation in all cell lines, when no FGF2 was added...

  13. Effect of irradiation and cooking methods on ascorbic acid levels of four potato cultivars

    International Nuclear Information System (INIS)

    Shirsat, S.G.; Thomas, Paul

    1998-01-01

    The changes in reduced and total ascorbic acid (AA) contents in control and in tubers irradiated to 100 Gy gamma rays for sprout inhibition were studied by HPLC and iodophenol titrimetry methods in four potato cultivars as a function of storage at 15 degC and after cooking by different methods. Both reduced and total ascorbic acid levels decreased in control tubers during the first 3 months in storage recording respectively 22 to 35% and 26 to 45% losses depending on the cultivar. Irradiated tubers recorded additional losses of 5 to 10% and 6.5 to 13%, respectively in reduced and total ascorbic acid levels during the same period but remained in good marketable conditions. Cooking of tubers in boiling water showed maximum loss in vitamin C content, whereas pressure and microwave cooking recorded least losses. The magnitude of losses in reduced and total vitamin C during cooking was comparable in control and in irradiated tubers. (author)

  14. Ascorbic acid protects lipids in human plasma and low-density lipoprotein against oxidative damage

    Energy Technology Data Exchange (ETDEWEB)

    Frei, B. (Department of Nutrition, Harvard School of Public Health, Boston, MA (Unites States))

    1991-12-01

    The authors exposed human blood plasma and low-density lipoprotein (LDL) to many different oxidative challenges and followed the temporal consumption of endogenous antioxidants in relation to the initiation of oxidative damage. Under all types of oxidizing conditions, ascorbic acid completely protects lipids in plasma and LDL against detectable peroxidative damage as assessed by a specific and highly sensitive assay for lipid peroxidation. Ascorbic acid proved to be superior to the other water-soluble plasma antioxidants bilirubin, uric acid, and protein thiols as well as to the lipoprotein-associated antioxidants alpha-tocopherol, ubiquinol-10, lycopene, and beta-carotene. Although these antioxidants can lower the rate of detectable lipid peroxidation, they are not able to prevent its initiation. Only ascorbic acid is reactive enough to effectively intercept oxidants in the aqueous phase before they can attack and cause detectable oxidative damage to lipids.

  15. Function of endothelium at adolescents with constitutional exogenous obesity before and after rehabilitation

    OpenAIRE

    Miroshnichenko, O.

    2011-01-01

    Function of endothelium at 43 adolescents with constitutional exogenous obesity before rehabilitation and at 33 healthy adolescents has been studied. Disorder of endothelial function has been established in 32 (74.4%) adolescents with constitutional exogenous obesity and in 7 (21.2%) healthy adolescents. We showed the efficiency of the rehabilitation program on restoration of endothelial function at adolescents with constitutional exogenous obesity.

  16. Speculative prototypes and exogenous ethnographies: Experiencing relationships beyond the human

    DEFF Research Database (Denmark)

    Jönsson, Li; Ulv Lenskjold, Tau

    2017-01-01

    This article deals with the role that speculative design prototypes have as means to intervene in contexts of everyday life in order to explore, and possibly facilitate, new types of relationships between human and non-human beings. Focusing on an off-centered design of the human, it seeks to exp...... to explore what types of new possibilities may arise when speculation in design meets the practice of doing what might be termed an "exogenous ethnography"....

  17. An interpretable LSTM neural network for autoregressive exogenous model

    OpenAIRE

    Guo, Tian; Lin, Tao; Lu, Yao

    2018-01-01

    In this paper, we propose an interpretable LSTM recurrent neural network, i.e., multi-variable LSTM for time series with exogenous variables. Currently, widely used attention mechanism in recurrent neural networks mostly focuses on the temporal aspect of data and falls short of characterizing variable importance. To this end, our multi-variable LSTM equipped with tensorized hidden states is developed to learn variable specific representations, which give rise to both temporal and variable lev...

  18. Managers with and without Style: Evidence Using Exogenous Variation

    OpenAIRE

    C. Edward Fee; Charles J. Hadlock; Joshua R. Pierce

    2013-01-01

    In a large panel of Compustat firms, we find that firm policy changes after exogenous CEO departures do not display abnormally high levels of variability, casting doubt on the presence of idiosyncratic-style effects in policy choices. After endogenous CEO departures, we do detect abnormally large policy changes. These changes are larger when the firm is likely to draw from a deeper pool of replacement CEO candidates, suggesting the presence of causal-style effects that are anticipated by the ...

  19. Functional Forms, Exogenous Shifts, and Economic Surplus Changes

    OpenAIRE

    Xueyan Zhao; John D. Mullen; Gary R. Griffith

    1997-01-01

    Conditions for exact welfare measures in equilibrium displacement modeling are examined. These relate to the functional form of supply and demand, the nature of the exogenous shift, and the definition of percentage changes. Approximation errors when these conditions are not met in empirical applications are investigated and analytical expressions for the errors derived. Significant errors are possible when a proportional shift is assumed. The assumptions underlying Alston and Wohlgenant's emp...

  20. Measuring Concentration in Data with an Exogenous Order

    OpenAIRE

    Abedieh, Jasmin; Groll, Andreas; Eugster, Manuel J. A.

    2013-01-01

    Concentration measures order the statistical units under observation according to their market share. However, there are situations where an order according to an exogenous variable is more appropriate or even required. The present article introduces a generalized definition of market concentration and defines a corresponding concentration measure. It is shown that this generalized concept of market concentration satisfies the common axioms of (classical) concentration measures. In an appl...

  1. Peer Effects in Exogenously Formed University Student Groups

    OpenAIRE

    Gregory Androushchak; Oleg Poldin; Maria Yudkevich

    2012-01-01

    We estimate the influence of classmates’ ability characteristics on student achievement in exogenously formed student groups. The study uses administrative data on undergraduate students at a large selective university in Russia. The presence of high-ability classmates has a positive effect on individual academic performance, and students at the top of the ability distribution derive the greatest benefit from their presence. An increase in the proportion of less able students has an insignifi...

  2. Expression and analysis of exogenous proteins in epidermal cells.

    Science.gov (United States)

    Dagnino, Lina; Ho, Ernest; Chang, Wing Y

    2010-01-01

    In this chapter we review protocols for transient transfection of primary keratinocytes. The ability to transfect primary epidermal cells regardless of their differentiation status allows the biochemical and molecular characterization of multiple proteins. We review methods to analyze exogenous protein abundance in transfected keratinocytes by immunoblot and immunoprecipitation. We also present protocols to determine the subcellular distribution of these proteins by indirect immunofluorescence microscopy approaches.

  3. Control of exogenous factors affecting plasma homovanillic acid concentration.

    Science.gov (United States)

    Davidson, M; Giordani, A B; Mohs, R C; Mykytyn, V V; Platt, S; Aryan, Z S; Davis, K L

    1987-04-01

    Measurements of plasma homovanillic acid (pHVA) concentrations appear to be a valid research strategy in psychiatric disorders in which a central dopamine (DA) abnormality has been implicated. This study provides guidance about the control of some of the exogenous factors affecting pHVA concentrations. Fasting for 14 hours eliminates the dietary effects on pHVA in healthy human subjects. Changing position, walking for 30 minutes, or smoking two cigarettes has no effect on pHVA concentrations.

  4. Synergistic effects of sodium 
ascorbate and acetone to restore compromised bond strength 
after enamel bleaching.

    Science.gov (United States)

    Boruziniat, Alireza; Manafi, Safa; Cehreli, Zafer C

    To evaluate the effect of a new experimental solution containing sodium ascorbate (SA) and acetone on reversing compromised bonding to enamel immediately after bleaching. The buccal surface of intact, extracted human premolars (n = 60) was bleached. The teeth were then randomly assigned to 6  groups according to the type of pretreatment applied prior to adhesive procedures: 10% SA in acetone-water solution applied for 1 and 5 min (groups 1 and 2, respectively); aqueous solution of 10% SA applied for 10 min (group 3); 100% acetone applied for 10 min (group 4); no pretreatment (negative control; group 5). An additional group (positive control; group 6) comprised unbleached teeth (n = 12). Two composite microcylinders were bonded on each specimen for evaluation of microshear bond strength (MBS) and failure modes. Data were analyzed using the one-way ANOVA and Tukey's post-hoc and chi-square tests at P = 0.05. Groups 1 and 2 yielded similar MBS values to groups 4 and 6 (positive control). The mean MBS of groups 3 and 5 (negative control) were similar, and significantly lower than that of the positive control group. The application of 10% SA in an acetone-water solution prior to bonding procedures can restore compromised enamel bond strength to its unbleached state within a clinically acceptable time of 1 min.

  5. Ascorbic acid deficiency stimulates hepatic expression of inflammatory chemokine, cytokine-induced neutrophil chemoattractant-1, in scurvy-prone ODS rats.

    Science.gov (United States)

    Horio, Fumihiko; Kiyama, Keiichiro; Kobayashi, Misato; Kawai, Kaori; Tsuda, Takanori

    2006-02-01

    ODS rat has a hereditary defect in ascorbic acid biosynthesis and is a useful animal model for elucidating the physiological role of ascorbic acid. We previously demonstrated by using ODS rats that ascorbic acid deficiency changes the hepatic gene expression of acute phase proteins, as seen in acute inflammation. In this study, we investigated the effects of ascorbic acid deficiency on the production of inflammatory chemokine, cytokine-induced neutrophil chemoattractant-1 (CINC-1), in ODS rats. Male ODS rats (6 wk of age) were fed a basal diet containing ascorbic acid (300 mg/kg diet) or a diet without ascorbic acid for 14 d. Obvious symptoms of scurvy were not observed in the ascorbic acid-deficient rats. Ascorbic acid deficiency significantly elevated the serum concentration of CINC-1 on d 14. The liver and spleen CINC-1 concentrations in the ascorbic acid-deficient rats were significantly elevated to 600% and 180% of the respective values in the control rats. However, the lung concentration of CINC-1 was not affected by ascorbic acid deficiency. Ascorbic acid deficiency significantly elevated the hepatic mRNA level of CINC-1 (to 480% of the value in the control rats), but not the lung mRNA level. These results demonstrate that ascorbic acid deficiency elevates the serum, liver and spleen concentrations of CINC-1 as seen in acute inflammation, and suggest that ascorbic acid deficiency stimulate the hepatic CINC-1 gene expression.

  6. [Exogenous Sr2+ sedimentation on otolith of chum salmon embryos].

    Science.gov (United States)

    Wang, Chen; Liu, Wei; Zhan, Pei-rong; Wang, Ji-long; Li, Pei-lun

    2015-10-01

    To explore the exogenous Sr2+ sedimentation on otolith of chum salmon embryos, chum salmon embryos were exposed to culture water contained Sr2+ at Sr2+ concentration of 50, 100, 200 or 400 mg . L-1 for 48 h to imitate Sr2+ sedimentation. After a culturing period of 12 d and 100 d, the otoliths of the chum salmon were taken to detect exogenous Sr2+ sedimentation with electro-probe microanalyzer (EPMA). The results showed that obvious deep red strontium signatures were produced in the otolith of chum salmon at different concentrations of Sr2+. The mean and extreme values of peak strontium area were not stable for the same Sr2+ dose, but the lowest of all the peak values was 35.1 times as much as that of control. Overall, the strontium value increased with the increase of Sr2+concentration. The strontium peak had no signs of abating after a culture period of 100 d. The results also showed that strontium was gradually deposited in the otolith, and had obvious hysteresis to immersion. Strontium sedimentation could also return to a normal level after the peak. These characteristics accorded exactly with the requirement of discharge tag technology, which indicated that exogenous Sr2+ was suitable in the marking of salmon otolith.

  7. Exogenous lipoid pneumonia: high-resolution CT findings

    International Nuclear Information System (INIS)

    Lee, J.S.; Song, K.S.; Lim, T.H.; Im, J.G.; Seo, J.B.

    1999-01-01

    The aim of this study was to assess high-resolution computed tomography (HRCT) findings of exogenous lipoid pneumonia. High-resolution computed tomography was obtained in 25 patients with proven exogenous lipoid pneumonia resulting from aspiration of squalene (derived from shark liver oil). Diagnosis was based on biopsy (n = 9), bronchoalveolar lavage (n = 8), or sputum cytology and clinical findings (n = 8). The clinical history of taking squalene was confirmed in all patients. The CT findings were classified into three patterns: diffuse ground-glass opacity, consolidation, and interstitial abnormalities. Distribution of the abnormalities, duration of taking squalene, predisposing factors for aspiration, and route of administration were analyzed. Ten patients showed diffuse ground-glass opacity pattern. Seven of 10 patients had predisposing conditions such as unconsciousness, pharyngeal dysmotility, or motor disturbances, and 6 patients had a recent history of taking large amount of squalene through nasal route. Seven patients who had consolidation pattern had a history of taking squalene for several months and did not have any predisposing factor. All of the 5 patients who had a pattern of interstitial abnormalities had a history of taking squalene longer than 1 year and showed segmental distribution of interstitial thickening with interposing ground-glass opacities. Three patients simultaneously had two different patterns at different lobes of the lung. The HRCT findings of lipoid pneumonia are ground-glass opacities, consolidation, and interstitial abnormalities. These HRCT findings with appropriate inquiries could be useful for diagnosis of exogeneous lipoid pneumonia. (orig.)

  8. Glucocorticoid-related bone changes from endogenous or exogenous glucocorticoids.

    Science.gov (United States)

    Warriner, Amy H; Saag, Kenneth G

    2013-12-01

    Glucocorticoids have a negative impact on bone through direct effects on bone cells and indirect effects on calcium absorption. Here, recent findings regarding glucocorticoid-induced osteoporosis, bone changes in patients with endogenous glucocorticoid derangements, and treatment of steroid-induced bone disease are reviewed. Although the majority of our understanding arises from the outcomes of patients treated with exogenous steroids, endogenous overproduction appears to be similarly destructive to bone, but these effects are reversible with cure of the underlying disease process. Additionally, there are bone changes that occur in diseases that interrupt adrenal glucocorticoid production, both in response to our inability to perfectly match glucocorticoid replacement and also related to the underlying disease process. More investigation is required to understand which patients with endogenous overproduction or underproduction of glucocorticoid would benefit from osteoporosis treatment. Better understood is the benefit that can be achieved with currently approved treatments for glucocorticoid-induced osteoporosis from exogenous steroids. With growing concern of long-term use of bisphosphonates, however, further investigation into the duration of use and use in certain populations, such as children and premenopausal women, is essential. Glucocorticoid-induced osteoporosis is a complex disease that is becoming better understood through advances in the study of exogenous and endogenous glucocorticoid exposure. Further advancement of proper treatment and prevention is on the horizon.

  9. Electrocatalytic oxidation and voltammetric determination of ciprofloxacin employing poly(alizarin red)/graphene composite film in the presence of ascorbic acid, uric acid and dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xin; Wei, Youli; Ding, Yaping, E-mail: wdingyp@sina.com

    2014-07-04

    Graphical abstract: An electrochemical sensor based on PAR/EGR/GCE via a cooperation of the potentiostatic technique and cyclic voltammetry was first fabricated for the determination of CPFX with satisfied detecting result of real samples. - Highlights: • PAR/EGR composite film was prepared for the first time. • The sensor can be applied to determinate CPFX in the presence of AA, UA and DA. • The sensor indicated the feasibility in drug samples and biological media. - Abstract: A glassy carbon electrode modified with poly(alizarin red)/electrodeposited graphene (PAR/EGR) composite film was prepared and applied to detect ciprofloxacin (CPFX) in the presence of ascorbic, uric acid and dopamine. The morphology and interface property of PAR/EGR films were examined by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The electrocatalytic oxidation of CPFX on AR/EGR was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The linearity ranged from 4 × 10{sup −8} to 1.2 × 10{sup −4} M with a detection limit (S/N = 3) of 0.01 μM. The modified electrode could be applied to the individual determination of CPFX as well as the simultaneous determination of CPFX, ascorbic acid, uric acid and dopamine. This method proved to be a simple, selective and rapid way to determine CPFX in pharmaceutical preparation and biological media.

  10. Electrocatalytic oxidation and voltammetric determination of ciprofloxacin employing poly(alizarin red)/graphene composite film in the presence of ascorbic acid, uric acid and dopamine

    International Nuclear Information System (INIS)

    Zhang, Xin; Wei, Youli; Ding, Yaping

    2014-01-01

    Graphical abstract: An electrochemical sensor based on PAR/EGR/GCE via a cooperation of the potentiostatic technique and cyclic voltammetry was first fabricated for the determination of CPFX with satisfied detecting result of real samples. - Highlights: • PAR/EGR composite film was prepared for the first time. • The sensor can be applied to determinate CPFX in the presence of AA, UA and DA. • The sensor indicated the feasibility in drug samples and biological media. - Abstract: A glassy carbon electrode modified with poly(alizarin red)/electrodeposited graphene (PAR/EGR) composite film was prepared and applied to detect ciprofloxacin (CPFX) in the presence of ascorbic, uric acid and dopamine. The morphology and interface property of PAR/EGR films were examined by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The electrocatalytic oxidation of CPFX on AR/EGR was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The linearity ranged from 4 × 10 −8 to 1.2 × 10 −4 M with a detection limit (S/N = 3) of 0.01 μM. The modified electrode could be applied to the individual determination of CPFX as well as the simultaneous determination of CPFX, ascorbic acid, uric acid and dopamine. This method proved to be a simple, selective and rapid way to determine CPFX in pharmaceutical preparation and biological media

  11. Factors that affect leaf extracellular ascorbic acid content and redox status

    Energy Technology Data Exchange (ETDEWEB)

    Burkey, K.O.; Fiscus, E.L. [North Carolina State Univ., United States dept. og Agriculture-Agricultural Research Service and Dept. of Crop Science, Raleigh, NC (United States); Eason, G. [North Carolina, State Univ., United States Dept. of Plant Pathology, Raleigh, NC (United States)

    2003-01-01

    Leaf ascorbic acid content and redox status were compared in ozone-tolerant (Provider) and ozone-sensitive (S156) genotypes of snap bean (Phaseolus vulgaris L.). Plants were grown in pots for 24 days under charcoal-filtered air (CF) conditions in open-top field chambers and then maintained as CF controls (29 nmol mol{sup 1} ozone) or exposed to elevated ozone (71 nmol mol{sup 1} ozone). Following a 10-day treatment, mature leaves of the same age were harvested early in the morning (06:00-08:00 h) or in the afternoon (13:00-15:00 h) for analysis of ascorbic acid (AA) and dehydroascorbic acid (DHA). Vacuum infiltration methods were used to separate leaf AA into apoplast and symplast fractions. The total ascorbate content [AA + DHA] of leaf tissue averaged 28% higher in Provider relative to S156, and Provider exhibited a greater capacity to maintain [AA + DHA] content under ozone stress. Apoplast [AA + DHA] content was 2-fold higher in tolerant Provider (360 nmol g{sup 1} FW maximum) relative to sensitive S156 (160 nmol g1 FW maximum) regardless of sampling period or treatment, supporting the hypothesis that extracellular AA is a factor in ozone tolerance. Apoplast [AA + DHA] levels were significantly higher in the afternoon than early morning for both genotypes, evidence for short-term regulation of extracellular ascorbate content. Total leaf ascorbate was primarily reduced with AA/[AA + DHA] ratios of 0.81-0.90. In contrast, apoplast AA/[AA + DHA] ratios were 0.01-0.60 and depended on genotype and ozone treatment. Provider exhibited a greater capacity to maintain extracellular AA/[AA + DHA] ratios under ozone stress, suggesting that ozone tolerance is associated with apoplast ascorbate redox status. (au)

  12. Protective role of ascorbic acid in the decontamination of cow milk casein by gamma-irradiation.

    Science.gov (United States)

    Kouass Sahbani, Saloua; Klarskov, Klaus; Aloui, Amine; Kouass, Salah; Landoulsi, Ahmed

    2013-06-01

    The aim of this work was to investigate the protective role of ascorbic acid on irradiation-induced modification of casein. Casein stock solutions were irradiated with increasing doses 2-10 kGy using (60)Co Gamma rays at a dose rate D• = 136.73 Gy/min at room temperature. The total viable microorganism content of cow milk casein was evaluated by Plate Count Agar (PCA) incubation for 48 h at 37°C. Sodium dodecylsulfate gel electrophoresis (SDS-PAGE) and Matrix-Assisted Laser Desorption-Ionization Time-of-Flight mass spectrometry (MALDI-TOF-MS) analysis were used to evaluate the effect of gamma irradiation on casein integrity. Gamma irradiation reduced the bacterial contamination of casein solutions at a lower irradiation dose when performed in the presence of ascorbic acid. The irradiation treatment of casein in the absence of ascorbic acid with a dose of 4 kGy could reduce 99% of the original amount of bacterial colonies. However, in the presence of ascorbic acid the irradiation treatment of casein with a dose lower than 2 kGy could reduce 99% of the original amount of bacterial colonies which suggested that the irradiation dose lower than 2 kGy achieved almost the entire decontamination result. SDS-PAGE and MALDI-TOF-MS analysis showed that ascorbic acid protected cow milk casein from degradation and subsequent aggregation probably by scavenging oxygen and protein radicals produced by the irradiation. It is demonstrated that the combination of gamma irradiation and ascorbic acid produce additive effects, providing acceptable hygienic quality of cow milk casein and protects caseins against Reactive Oxygen Species (ROS) generated, during the irradiation process.

  13. The comparison of techniques and methods for L-ascorbic acid determination in the fruits

    Directory of Open Access Journals (Sweden)

    Cvetković Biljana R.

    2012-01-01

    Full Text Available Vitamin C is an essential vitamin for human nutrition; with the L-ascorbic acid (AA being the active form of vitamin C. Hence, determination of the L-ascorbic acid in the natural and processed foods is very important. In the past, plenty of methods based on the reversible redox reaction of AA oxidation/DHA reduction were developed. Because of L-ascorbic acid instability in aqueous solutions, it is useful to analyze various types of extraction. The aim of this study is to compare three different methods and three different extractants for the L-ascorbic acid determination. Fruits (kiwi, lemon, orange, and grapefruit were purchased from a local market. The L-ascorbic acid in these four samples was determined by the three different methods: the AOAC, the HPLC method with three different types of extractions, and the colorimetric method using ascorbate-oxidase. For the HPLC measurements, one part of the fruits was extracted with distilled water, the second with potassium hydrogen phosphate, and the third with 3% meta-phosphoric acid (MPA in 8% acetic acid. The HPLC measurements of each sample were repeated three times, the AOAC titration was repeated five times, and in the calorimetric method three measurements were performed. The results were statistically evaluated related to sample basis. Statistical analysis shows that there is a significant difference between the results for all three methods of extraction for all samples, except for the grapefruit sample where no significant difference was observed between the results obtained after the buffer extraction (E2 and the metaphosphoric acid in acetic acid extraction (E3. Discriminative analysis for the HPLC determinations proves that there is a clear difference and defined border between the samples in relation to the methods of extraction during the HPLC determination.

  14. Effect of Ascorbic Acid on Noise Induced Hearing Loss in Rats

    Directory of Open Access Journals (Sweden)

    Ziba Loukzadeh

    2015-07-01

    Full Text Available Introduction: After presbycusis, noise-induced hearing loss is the second most common cause of acquired hearing loss. Numerous studies have shown that high-intensity noise exposure increases free radical species; therefore, use of antioxidants to detoxify the free radicals can prevent cellular damage in the cochlea. We studied the potential hearing protective effect of different doses of ascorbic acid administered prior to noise exposure in rats.   Materials and Methods: Twenty-four male albino Wistar rats were randomly allocated into four groups: groups A, B, and C received 1250, 250, and 50 mg/kg/day of ascorbic acid, respectively, and group D acted as the control group. After 14 days of ascorbic acid administration, the rats were exposed to noise (105 dB sound pressure level for 2 h. Distortion product otoacoustic emissions (DPOAE were recorded prior to starting the ascorbic acid as baseline and 1 h after the noise exposure.   Results: The amplitude decrease was 14.99 dB for group A, 16.11 dB for group B, 28.82 dB for group C, and 29.91 dB for the control group. Moderate and high doses of ascorbic acid significantly reduced the transient threshold shift in the rats.   Conclusion:  The results of present study support the concept of cochlea protection by antioxidant agents. This dose-dependent protective effect was shown through the use of ascorbic acid treatment prior to noise exposure.

  15. Synthesis of colloidal silver nanoparticle clusters and their application in ascorbic acid detection by SERS.

    Science.gov (United States)

    Cholula-Díaz, Jorge L; Lomelí-Marroquín, Diana; Pramanick, Bidhan; Nieto-Argüello, Alfonso; Cantú-Castillo, Luis A; Hwang, Hyundoo

    2018-03-01

    Ascorbic acid (vitamin C) has an essential role in the human body mainly due to its antioxidant function. In this work, metallic silver nanoparticle (AgNP) colloids were used in SERS experiments to detect ascorbic acid in aqueous solution. The AgNPs were synthesized by a green method using potato starch as reducing and stabilizing agent, and water as the solvent. The optical properties of the yellowish as-synthesized silver colloids were characterized by UV-vis spectroscopy, in which besides a typical band at 410 nm related to the localized surface plasmon resonance of the silver nanoparticles, a shoulder band around 500 nm, due to silver nanoparticle cluster formation, is presented when relatively higher concentrations of starch are used in the synthesis. These starch-capped silver nanoparticles show an intrinsic Raman peak at 1386 cm -1 assigned to deformation modes of the starch structure. The increase of the intensity of the SERS peak at 1386 cm -1 with an increase in the concentration of the ascorbic acid is related to a decrease of the gap between dimers and trimers of the silver nanoparticle clusters produced by the presence of ascorbic acid in the colloid. The limit of detection of this technique for ascorbic acid is 0.02 mM with a measurement concentration range of 0.02-10 mM, which is relevant for the application of this method for detecting ascorbic acid in biological specimen. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Tear ascorbic acid levels and the total antioxidant status in contact lens wearers: A pilot study

    Directory of Open Access Journals (Sweden)

    Venkata Sai

    2009-01-01

    Full Text Available Aims: The tear ascorbate owing to its high concentration, functions as an effective antioxidant against the oxidative damage of cornea. Contact lens wearers (CLW are prone to oxidative stress due to the lens-induced hypoxic conditions. A pilot study was done to compare the tear ascorbic acid level and the total antioxidant capacity give as in normal and CLW. Materials and Methods: In this study 21 CLW (Mean age 23 ± 3 years ; M-2, F-19, who were daily wear users, with duration of wear not more than four years, along with age-matched 28 controls (Mean age 28 ± 3 ; M-15, F-13 were recruited in the study for collection of reflex tears using Schirmer′s strip. Ascorbic acid in tears was determined using high-performance liquid chromatography (HPLC, total antioxidant capacity (TAC and total protein assay by spectrophotometric analysis. Results: CLW showed no significant change in the tear ascorbic acid levels (0.4 ± 0.26 mM compared to the control subjects (0.61 ± 0.59 mM. The amount of ascorbic acid in tears did not correlate with the TAC or the total protein of the tears. The mean TAC in CLW was 0.69 ± 0.16 mM, with a total protein of 1.35 ± 0.46 mg/ml while in controls it was 0.7 ± 0.18 mM and 1.21 ± 0.47 mg/ml respectively . Conclusions: Soft contact lens wear did not show any significant change in tear ascorbic acid, TAC and total protein levels compared to controls.

  17. Simultaneous determination of rutin and ascorbic acid in a sequential injection lab-at-valve system.

    Science.gov (United States)

    Al-Shwaiyat, Mohammed Khair E A; Miekh, Yuliia V; Denisenko, Tatyana A; Vishnikin, Andriy B; Andruch, Vasil; Bazel, Yaroslav R

    2018-02-05

    A green, simple, accurate and highly sensitive sequential injection lab-at-valve procedure has been developed for the simultaneous determination of ascorbic acid (Asc) and rutin using 18-molybdo-2-phosphate Wells-Dawson heteropoly anion (18-MPA). The method is based on the dependence of the reaction rate between 18-MPA and reducing agents on the solution pH. Only Asc is capable of interacting with 18-MPA at pH 4.7, while at pH 7.4 the reaction with both Asc and rutin proceeds simultaneously. In order to improve the precision and sensitivity of the analysis, to minimize reagent consumption and to remove the Schlieren effect, the manifold for the sequential injection analysis was supplemented with external reaction chamber, and the reaction mixture was segmented. By the reduction of 18-MPA with reducing agents one- and two-electron heteropoly blues are formed. The fraction of one-electron heteropoly blue increases at low concentrations of the reducer. Measurement of the absorbance at a wavelength corresponding to the isobestic point allows strictly linear calibration graphs to be obtained. The calibration curves were linear in the concentration ranges of 0.3-24mgL -1 and 0.2-14mgL -1 with detection limits of 0.13mgL -1 and 0.09mgL -1 for rutin and Asc, respectively. The determination of rutin was possible in the presence of up to a 20-fold molar excess of Asc. The method was applied to the determination of Asc and rutin in ascorutin tablets with acceptable accuracy and precision (1-2%). Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Simultaneous determination of ascorbic acid, dopamine and uric acid based on tryptophan functionalized graphene

    International Nuclear Information System (INIS)

    Lian, Qianwen; He, Zhifang; He, Qian; Luo, Ai; Yan, Kaiwang; Zhang, Dongxia; Lu, Xiaoquan; Zhou, Xibin

    2014-01-01

    Highlights: • Trp-GR was synthesized by utilizing a facile ultrasonic method. • The material as prepared had well dispersivity in water and better conductivity than pure GR. • Trp-GR/GCE showed excellent potential for the determination of AA, DA and UA. • The proposed method was applied for the analysis of AA, DA and UA in real samples. - Abstract: A new type of tryptophan-functionalized graphene nanocomposite (Trp-GR) was synthesized by utilizing a facile ultrasonic method via π–π conjugate action between graphene (GR) and tryptophan (Trp) molecule. The material as prepared had well dispersivity in water and better conductivity than pure GR. The surface morphology of Trp-GR was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA), and uric acid (UA) were investigated by cyclic voltammetry (CV) on the surface of Trp-GR. The separation of the oxidation peak potentials for AA–DA, DA–UA and UA–AA was about 182 mV, 125 mV and 307 mV, which allowed simultaneously determining AA, DA, and UA. Differential pulse voltammetery (DPV) was used for the determination of AA, DA, and UA in their mixture. Under optimum conditions, the linear response ranges for the determination of AA, DA, and UA were 0.2–12.9 mM, 0.5–110 μM, and 10–1000 μM, with the detection limits (S/N = 3) of 10.09 μM, 0.29 μM and 1.24 μM, respectively. Furthermore, the modified electrode was investigated for real sample analysis

  19. Simultaneous determination of ascorbic acid, dopamine and uric acid based on tryptophan functionalized graphene

    Energy Technology Data Exchange (ETDEWEB)

    Lian, Qianwen; He, Zhifang; He, Qian; Luo, Ai; Yan, Kaiwang; Zhang, Dongxia [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Geography and Environment Science, Northwest Normal University, Lanzhou, 730070 (China); Lu, Xiaoquan, E-mail: Luxq@nwnu.edu.cn [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070 (China); Zhou, Xibin, E-mail: zhouxb@nwnu.edu.cn [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Geography and Environment Science, Northwest Normal University, Lanzhou, 730070 (China)

    2014-05-01

    Highlights: • Trp-GR was synthesized by utilizing a facile ultrasonic method. • The material as prepared had well dispersivity in water and better conductivity than pure GR. • Trp-GR/GCE showed excellent potential for the determination of AA, DA and UA. • The proposed method was applied for the analysis of AA, DA and UA in real samples. - Abstract: A new type of tryptophan-functionalized graphene nanocomposite (Trp-GR) was synthesized by utilizing a facile ultrasonic method via π–π conjugate action between graphene (GR) and tryptophan (Trp) molecule. The material as prepared had well dispersivity in water and better conductivity than pure GR. The surface morphology of Trp-GR was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA), and uric acid (UA) were investigated by cyclic voltammetry (CV) on the surface of Trp-GR. The separation of the oxidation peak potentials for AA–DA, DA–UA and UA–AA was about 182 mV, 125 mV and 307 mV, which allowed simultaneously determining AA, DA, and UA. Differential pulse voltammetery (DPV) was used for the determination of AA, DA, and UA in their mixture. Under optimum conditions, the linear response ranges for the determination of AA, DA, and UA were 0.2–12.9 mM, 0.5–110 μM, and 10–1000 μM, with the detection limits (S/N = 3) of 10.09 μM, 0.29 μM and 1.24 μM, respectively. Furthermore, the modified electrode was investigated for real sample analysis.

  20. A novel nanocomposites sensor for epinephrine detection in the presence of uric acids and ascorbic acids

    International Nuclear Information System (INIS)

    Lu Xiaoquan; Li Yaya; Du Jie; Zhou Xibin; Xue Zhonghua; Liu Xiuhui; Wang Zhihua

    2011-01-01

    Highlights: · A novel PPy/AuNPs/SWCNTs nanomaterials biosensor was prepared to the selective determination of EP. · The methods we employed to prepare PPy/AuNPs/SWCNTs nanomaterials are extremely simple. · The PPy/AuNPs/SWCNTs nanocomposites biosensor we got from the results of experiments can totally eliminate the interference from AA and distinguish EP from UA. - Abstract: A novel nanocomposites film of conducting polymers including single-walled carbon nanotubes (SWCNTs), polypyrrole (PPy) and gold nanoparticles (AuNPs) modified electrode has been applied in voltammetric sensors to detect epinephrine (EP) sensitively when ascorbic acids (AA) and uric acids (UA) exist. The nanocomposites film of conducting polymers which show an excellent electrocatalystic activity for the oxidation of EP and UA was characterized by scanning electron microscopy (SEM) and electrochemical methods. The catalytic peak currents obtained from differential pulse voltammetry (DPV) increased linearly with increasing EP concentrations in the range of 4.0 x 10 -9 -1.0 x 10 -7 M with a detection limit of 2.0 x 10 -9 M (S/N = 3), respectively. The results showed that the nanocomposites of conducting polymers can selectively determine EP in the coexistence of a large amount of UA and AA. In addition, the sensor exhibited excellent sensitivity, selectivity and stability. The PPy/AuNPs/SWCNTs nanocomposites film can also be satisfactorily used for detecting EP in epinephrine hydrochloride injection when contain AA and UA, which also shows good recovery for determination of EP in some biological fluids.

  1. A novel nanocomposites sensor for epinephrine detection in the presence of uric acids and ascorbic acids

    Energy Technology Data Exchange (ETDEWEB)

    Lu Xiaoquan, E-mail: luxq@nwnu.edu.cn [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, LanZhou, 730070 (China); Li Yaya; Du Jie; Zhou Xibin; Xue Zhonghua; Liu Xiuhui; Wang Zhihua [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, LanZhou, 730070 (China)

    2011-08-30

    Highlights: {center_dot} A novel PPy/AuNPs/SWCNTs nanomaterials biosensor was prepared to the selective determination of EP. {center_dot} The methods we employed to prepare PPy/AuNPs/SWCNTs nanomaterials are extremely simple. {center_dot} The PPy/AuNPs/SWCNTs nanocomposites biosensor we got from the results of experiments can totally eliminate the interference from AA and distinguish EP from UA. - Abstract: A novel nanocomposites film of conducting polymers including single-walled carbon nanotubes (SWCNTs), polypyrrole (PPy) and gold nanoparticles (AuNPs) modified electrode has been applied in voltammetric sensors to detect epinephrine (EP) sensitively when ascorbic acids (AA) and uric acids (UA) exist. The nanocomposites film of conducting polymers which show an excellent electrocatalystic activity for the oxidation of EP and UA was characterized by scanning electron microscopy (SEM) and electrochemical methods. The catalytic peak currents obtained from differential pulse voltammetry (DPV) increased linearly with increasing EP concentrations in the range of 4.0 x 10{sup -9}-1.0 x 10{sup -7} M with a detection limit of 2.0 x 10{sup -9} M (S/N = 3), respectively. The results showed that the nanocomposites of conducting polymers can selectively determine EP in the coexistence of a large amount of UA and AA. In addition, the sensor exhibited excellent sensitivity, selectivity and stability. The PPy/AuNPs/SWCNTs nanocomposites film can also be satisfactorily used for detecting EP in epinephrine hydrochloride injection when contain AA and UA, which also shows good recovery for determination of EP in some biological fluids.

  2. Cloning and Functional Analysis of the Promoter of an Ascorbate Oxidase Gene from Gossypium hirsutum

    OpenAIRE

    Xin, Shan; Tao, Chengcheng; Li, Hongbin

    2016-01-01

    Apoplastic ascorbate oxidase (AO) plays significant roles in plant cell growth. However, the mechanism of underlying the transcriptional regulation of AO in Gossypium hirsutum remains unclear. Here, we obtained a 1,920-bp promoter sequence from the Gossypium hirsutum ascorbate oxidase (GhAO1) gene, and this GhAO1 promoter included a number of known cis-elements. Promoter activity analysis in overexpressing pGhAO1::GFP-GUS tobacco (Nicotiana benthamiana) showed that the GhAO1 promoter exhibite...

  3. Kinetics and mechanism of reduction of cerium(IV) by ascorbic acid

    International Nuclear Information System (INIS)

    Bhatt, K.; Nand, K.C.

    1979-01-01

    The reduction of cerium(IV) has been studied in sulfuric acid medium using ascorbic acid as the reductant. The rate is found to be function of both Ce(IV) and AH 2 concentrations. Sulfuric acid retards the rate and the inverse order with respect to sulfuric acid is unity. The addition of chloride, bisulfate and sulfate of sodium show negative salt effect and an increase in the dielectric constant of the medium shows an accelerating effect on the reaction rate. Arrhenius parameters have been evaluated. A mechanism involving intermediate formation of ascorbate radical (AH) is proposed and the derived rate law agrees well with the experimental observations. (author)

  4. Relevance of DNA repair pathways on ascorbic acid effects on Echerichia Coli K-12 cells

    International Nuclear Information System (INIS)

    Slyus, M.A. van; Oliveira, R.L.B. da C.; Felzenszwalb, I.; Gomes, R.A.; Menck, C.F.

    1985-01-01

    Inactivation kinetics were performed with repair proficient and deficient Escherichia coli K-12 cells treated with oxidized solutions of ascorbic acid. The repair pathways controlled by the recA and uvrA gene products are essential for cell survival to the treatment. However, SOS chromotest result indicates that the SOS functions are only induced at high and toxic concentrations of the drug. Moreover, single strand breaks in DNA from treated cells are detected, demonstrating genome damage promoted by oxidized solutions of ascorbate. (M.A.C.) [pt

  5. Limit Theory for Panel Data Models with Cross Sectional Dependence and Sequential Exogeneity.

    Science.gov (United States)

    Kuersteiner, Guido M; Prucha, Ingmar R

    2013-06-01

    The paper derives a general Central Limit Theorem (CLT) and asymptotic distributions for sample moments related to panel data models with large n . The results allow for the data to be cross sectionally dependent, while at the same time allowing the regressors to be only sequentially rather than strictly exogenous. The setup is sufficiently general to accommodate situations where cross sectional dependence stems from spatial interactions and/or from the presence of common factors. The latter leads to the need for random norming. The limit theorem for sample moments is derived by showing that the moment conditions can be recast such that a martingale difference array central limit theorem can be applied. We prove such a central limit theorem by first extending results for stable convergence in Hall and Hedye (1980) to non-nested martingale arrays relevant for our applications. We illustrate our result by establishing a generalized estimation theory for GMM estimators of a fixed effect panel model without imposing i.i.d. or strict exogeneity conditions. We also discuss a class of Maximum Likelihood (ML) estimators that can be analyzed using our CLT.

  6. A collagen-based scaffold delivering exogenous microrna-29B to modulate extracellular matrix remodeling.

    Science.gov (United States)

    Monaghan, Michael; Browne, Shane; Schenke-Layland, Katja; Pandit, Abhay

    2014-04-01

    Directing appropriate extracellular matrix remodeling is a key aim of regenerative medicine strategies. Thus, antifibrotic interfering RNA (RNAi) therapy with exogenous microRNA (miR)-29B was proposed as a method to modulate extracellular matrix remodeling following cutaneous injury. It was hypothesized that delivery of miR-29B from a collagen scaffold will efficiently modulate the extracellular matrix remodeling response and reduce maladaptive remodeling such as aggressive deposition of collagen type I after injury. The release of RNA from the scaffold was assessed and its ability to silence collagen type I and collagen type III expression was evaluated in vitro. When primary fibroblasts were cultured with scaffolds doped with miR-29B, reduced levels of collagen type I and collagen type III mRNA expression were observed for up to 2 weeks of culture. When the scaffolds were applied to full thickness wounds in vivo, reduced wound contraction, improved collagen type III/I ratios and a significantly higher matrix metalloproteinase (MMP)-8: tissue inhibitor of metalloproteinase (TIMP)-1 ratio were detected when the scaffolds were functionalized with miR-29B. Furthermore, these effects were significantly influenced by the dose of miR-29B in the collagen scaffold (0.5 versus 5 μg). This study shows a potential of combining exogenous miRs with collagen scaffolds to improve extracellular matrix remodeling following injury.

  7. The effect of exogenous 24-epibrassinolide on the ecdysteroid content in the leaves of Spinacia oleracea L.

    Science.gov (United States)

    Kamlar, Marek; Rothova, Olga; Salajkova, Sarka; Tarkowska, Dana; Drasar, Pavel; Kocova, Marie; Harmatha, Juraj; Hola, Dana; Kohout, Ladislav; Macek, Tomas

    2015-05-01

    The aim of this study was to show whether/how the application of exogenous 24-epibrassinolide can affect the content of ecdysteroids in spinach leaves. Brassinosteroids and ecdysteroids, structurally related phytosterols, show effect on a range of processes in plants. Brassinosteroids increase biomass yield in some species, photosynthesis and resistance to stress, and ecdysteroids show effect on proteins responsible for binding of CO2 or water cleavage. The mutual interaction of these sterols in plants is unclear. The UPLC-(+)ESI-MS/MS analyses of extracts of treated and untreated spinach (Spinacia oleracea L.) leaves show that the application of exogenous 24-epibrassinolide does influence the ecdysteroid content in plant tissues. The response differs for the major ecdysteroids and also differs from that for the minor ones and is dependent on the developmental stage of the leaves within the same plant or the 24-epibrassinolide concentration applied. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. The browning kinetics of the non-enzymatic browning reaction in L-ascorbic acid/basic amino acid systems

    Directory of Open Access Journals (Sweden)

    Ai-Nong YU

    Full Text Available Abstract Under the conditions of weak basis and the reaction temperature range of 110-150 °C, lysine, arginine and histidine were reacted with L-ascorbic acid at equal amount for 30-150 min, respectively and the formation of browning products was monitored with UV–vis spectrometry. The kinetic characteristics of their non-enzymatic browning reaction were investigated. The study results indicated that the non-enzymatic browning reaction of these three amino acids with L-ascorbic acid to form browning products was zero-order reaction. The apparent activation energies for the formation of browning products from L-ascorbic acid/lysine, L-ascorbic acid/arginine and L-ascorbic acid/histidine systems were 54.94, 50.08 and 35.31kJ/mol. The activation energy data indicated the degree of effects of reaction temperature on non-enzymatic browning reaction. Within the temperature range of 110-150 °C, the reaction rate of L-ascorbic acid/lysine system was the fastest one, followed by that of the L-ascorbic acid/arginine system. The reaction rate of L-ascorbic acid/histidine system was the slowest one. Based on the observed kinetic data, the formation mechanisms of browning products were proposed.

  9. UlaR activates expression of the ula operon in Streptococcus pneumoniae in the presence of ascorbic acid

    NARCIS (Netherlands)

    Afzal, Muhammad; Shafeeq, Sulman; Henriques-Normark, Birgitta; Kuipers, Oscar P

    In this study, the regulatory mechanism of the ula (utilization of l-ascorbic acid) operon, putatively responsible for transport and utilization of ascorbic acid in Streptococcus pneumoniae strain D39, is studied. β-Galactosidase assay data demonstrate that expression of the ula operon is increased

  10. Uptake of ascorbic acid by freshly isolated cells and secretory granules from the intermediate lobe of ox hypophyses

    DEFF Research Database (Denmark)

    Zhou, A; Matsumoto, T; Farver, O

    1990-01-01

    Mechanically isolated cells from the intermediate lobe of ox hypophyses contained 40.6 +/- 3.7 nmol mg-1 protein (mean +/- SE, n = 5) of ascorbic acid. They accumulated radioactivity time dependently, on incubation with L-[14C]ascorbic acid in ionic medium dominated by NaCl. No definite saturation...

  11. Low brain ascorbic acid increases susceptibility to seizures in mouse models of decreased brain ascorbic acid transport and Alzheimer’s disease

    OpenAIRE

    Warner, Timothy A; Kang, Jing-Qiong; Kennard, John A; Harrison, Fiona E

    2014-01-01

    Seizures are a known co-occurring symptom of Alzheimer’s disease, and they can accelerate cognitive and neuropathological dysfunction. Sub-optimal vitamin C (ascorbic acid) deficiency, that is low levels that do not lead the sufferer to present with clinical signs of scurvy (e.g. lethargy, hemorrhage, hyperkeratosis), are easily obtainable with insufficient dietary intake, and may contribute to the oxidative stress environment of both Alzheimer’s disease and epilepsy. The purpose of this stud...

  12. Ascorbic Acid Alleviates Damage from Heat Stress in the Photosystem II of Tall Fescue in Both the Photochemical and Thermal Phases

    Directory of Open Access Journals (Sweden)

    Ke Chen

    2017-08-01

    Full Text Available L-Ascorbate (Asc plays important roles in plant development, hormone signaling, the cell cycle and cellular redox system, etc. The higher content of Asc in plant chloroplasts indicates its important role in the photosystem. The objective of this study was to study the roles of Asc in tall fescue leaves against heat stress. After a heat stress treatment, we observed a lower value of the maximum quantum yield for primary photochemistry (φPo, which reflects the inhibited activity of the photochemical phase of photosystem II (PSII. Moreover, we observed a higher value of efficiency of electron transfer from QB to photosystem I acceptors (δR0, which reflects elevated activity of the thermal phase of the photosystem of the tall fescue. The addition of Asc facilitate the behavior of the photochemical phase of the PSII by lowering the ROS content as well as that of the alternative electron donor to provide electron to the tyrosine residue of the D1 protein. Additionally, exogenous Asc reduces the activity of the thermal phase of the photosystem, which could contribute to the limitation of energy input into the photosystem in tall fescue against heat stress. Synthesis of the Asc increased under heat stress treatment. However, under heat stress this regulation does not occur at the transcription level and requires further study.

  13. Applied physics

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    The Physics Division research program that is dedicated primarily to applied research goals involves the interaction of energetic particles with solids. This applied research is carried out in conjunction with the basic research studies from which it evolved

  14. Effect of L-ascorbic acid on nickel-induced alterations in serum lipid profiles and liver histopathology in rats.

    Science.gov (United States)

    Das, Kusal K; Gupta, Amrita Das; Dhundasi, Salim A; Patil, Ashok M; Das, Swastika N; Ambekar, Jeevan G

    2006-01-01

    Nickel exposure greatly depletes intracellular ascorbate and alters ascorbate-cholesterol metabolism. We studied the effect of the simultaneous oral treatment with L-ascorbic acid (50 mg/100 g body weight (BW) and nickel sulfate (2.0 mg/100 g BW, i.p) on nickelinduced changes in serum lipid profiles and liver histopathology. Nickel-treated rats showed a significant increase in serum low-density lipoprotein-cholesterol, total cholesterol, triglycerides, and a significant decrease in serum high-density lipoprotein-cholesterol. In the liver, nickel sulfate caused a loss of normal architecture, fatty changes, extensive vacuolization in hepatocytes, eccentric nuclei, and Kupffer cell hypertrophy. Simultaneous administration of L-ascorbic acid with nickel sulfate improved both the lipid profile and liver impairments when compared with rats receiving nickel sulfate only. The results indicate that L-ascorbic acid is beneficial in preventing nickel-induced lipid alterations and hepatocellular damage.

  15. Plasma ascorbic acid, a priori diet quality score, and incident hypertension

    NARCIS (Netherlands)

    Buijsse, Brian; Jacobs, D.R.; Steffen, L.M.; Kromhout, Daan; Gross, M.D.

    2015-01-01

    Vitamin C may reduce risk of hypertension, either in itself or by marking a healthy diet pattern. We assessed whether plasma ascorbic acid and the a priori diet quality score relate to incident hypertension and whether they explain each other's predictive abilities. Data were from 2884 black and

  16. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex

    Energy Technology Data Exchange (ETDEWEB)

    Arya, S. P.; Mahajan, M. [Haryana, Kurukshetra Univ. (India). Dept. of Chemistry

    1998-05-01

    A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 {mu}g ml{sup -1}. Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C. [Italiano] Si propone un rapido e semplice metodo spettrofotometrico per la determinazione dell`acido ascorbico. L`acido ascorbico riduce il ferro(III) a ferro(II) che forma con la dimetilgliossima, in presenza di piridina, un complesso colorato in rosso. L`assorbanza della soluzione risultante e` misurata a 514 nm e si ottiene una relazione lineare tra assorbanza e concentrazione dell`acido ascorbico fino a 14 {mu}g ml{sup -1}. Si sono condotti studi sugli interferenti usualmente associati all`acido ascorbico ed e` stata valutata l`applicabilita` del metodo all`analisi di preparati farmaceutici di vitamina C.

  17. Investigation of L(+)-Ascorbic Acid with Raman Spectroscopy in Visible and UV Light

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    2015-01-01

    Abstract: Raman spectroscopy investigations of l(+)-ascorbic acid and its mono- and di-deprotonated anions (AH(-) and A(2-)) are reviewed and new measurements reported with several wavelengths, 229, 244, 266, 488, and 532nm. Results are interpreted, assisted by new DFT/B3LYP quantum chemical calc......). Relatively weak preresonance enhancement was seen for A(2-) when excitation was done with 229nm UV light, allowing water bands to become observable as for normal visible light Raman spectra....... calculations with 6-311++G(d,p) basis sets for several conformations of ascorbic acid and the anions. Raman spectra were measured during titration with NaOH base in an oxygen-poor environment to avoid fluorescence when solutions were alkaline. The ultraviolet (UV) absorption band for ascorbic acid in aqueous......cm(-1). Finally, for the ascorbate di-anion, absorption was found at similar to 298.4nm with molar absorptivity of similar to 7,000 L mol(-1) cm(-1) and below similar to 220nm. With UV light (244 and 266nm), strongly basic solutions gave pronounced Raman resonance enhancement at similar to 1556cm(-1...

  18. Effects of Ascorbic Acid on Garlic-induced Alterations in Semen ...

    African Journals Online (AJOL)

    Effects of Ascorbic Acid on Garlic-induced Alterations in Semen Parameters Of Wistar Rats. GO Omotoso, IO Onanuga, AAG Jimoh. Abstract. No Abstract. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · http://dx.doi.org/10.4314/tjhc.v18i2.69616 · AJOL African Journals ...

  19. Use of equimolar cysteine/ascorbic acids to recover MCP synthesized Ti(Mg) alloy

    CSIR Research Space (South Africa)

    Mushove, T

    2010-10-01

    Full Text Available Dissolution of waste by-products of mechanochemical processing (MCP) synthesis of Ti(Mg) alloy, from TiO2 and 15 wt.% excess Mg, was conducted in equimolar cysteine/ascorbic acids. The synthesized alloy is inherently mixed with MgO and other oxides...

  20. Effects of supplemental vitamin C (Ascorbic Acid) on the growth and ...

    African Journals Online (AJOL)

    Four different diets each containing 37.4% crude protein were formulated from locally available feed materials to contain 0 (control), 23, 46 and 92 mg/Kg supplemental Ascorbic acid (AA) respectively. Catfish with average weight of 2 - 6g were stocked and fed twice daily to satiation initially with Coppens fish feed for the first ...

  1. A proposed relationship between pH and ascorbic acid content of ...

    African Journals Online (AJOL)

    A relationship between the ascorbic acid content of fresh squeezed juice of orange, lemon, grape and lime and the pH was presented. The relationship established were statistically compared with those obtained by the 2,6 dichlorophenol indophenol titration method. It was shown that they do not differ significantly (p≥0.05) ...

  2. The Effects of Various Levels of Ascorbic Acid Intake Upon Oral Wound Healing in Guinea Pigs.

    Science.gov (United States)

    1983-01-01

    Pauling, L.C.: Ascorbic Acid and Glycosaminoglycans. An Orthomolecular Approach to Cancer and Other Diseases. Oncology. 37: 181, 1973. .- . .. 92 2 13...Metabolism or Vitamin C. Medicine . 20s 251, 1941. 37. Abt. A.F., Von Schuching, S., and Roe, J.s. Connective Tissue Studies. I. Relation of Dietary and

  3. Effects of Ascorbic Acid and Reduced Glutathione on the Alleviation of Salinity Stress in Olive Plants

    NARCIS (Netherlands)

    Aliniaeifard, S.; Hajilou, J.; Tabatabaei, S.J.; Seifi Kalhor, Maryam

    2016-01-01

    The aim of this study was to evaluate the effects of low molecular mass antioxidants and NaCl salinity on growth, ionic balance, proline, and water contents of ‘Zard’ olive trees under controlled greenhouse conditions. The experiment was carried out by spraying 2 mM of ascorbic acid (Asc) and 3

  4. [Nickel exposure to A549 cell damage and L-ascorbic acid interference effect].

    Science.gov (United States)

    Fu, Yao; Wang, Yue; Dan, Han; Zhang, Lin; Ma, Wenhan; Pan, Yulin; Wu, Yonghui

    2015-05-01

    Studying different concentrations of nickel smelting smoke subjects of human lung adenocarcinoma cells (A549) carcinogenic effects, discusses the influence of L-ascorbic acid protection. The A549 cells were divided into experimental and L-ascorbic acid in the intervention group. Plus exposure group concentration of nickel refining dusts were formulated 0.00, 6.25, 12.50, 25.00, 50.00, 100.00 µg/ml suspension, the intervention group on the basis of the added exposure group containing L-ascorbic acid (100 mmol/L), contact 24 h. Detection of cell viability by MTT assay. When the test substance concentration select 0.00, 25.00, 50.00, 100.00 µg/ml experiment for internal Flou-3 fluorescent probe to detect cell Ca²⁺ concentration, within DCFH-DA detect intracellular reactive oxygen (ROS) content, real-time quantitative PCR (real time, in the RT-PCR) was used to detect cell HIF-1α gene expression. With the increase of concentration, subjects increased cell growth inhibition rate, intracellular Ca²⁺ concentration increases, ROS content increased, HIF-1α gene expression increased, differences were statistically significant (P nickel exposure damage to cells. With subjects following exposure to nickel concentration increased, its effect on A549 cell damage increases, L-ascorbic acid cell damage caused by nickel has certain protective effect.

  5. Neurobehavioural and Neurotoxic Effects of L-ascorbic Acid and L ...

    African Journals Online (AJOL)

    Background: Lead is an environmental toxicant, occupational and environmental exposures remain a serious problem in developing and industrializing countries. Objective: This study is designed to investigate the effects of L-ascorbic acid and L-tryptophan on the neurotoxicity and neurobehavioural alterations in lead ...

  6. Plasma Ascorbic Acid in Insulin and Non-insulin Dependent Diabetes

    African Journals Online (AJOL)

    Blood glucose, plasma ascorbic acid and haemoglobin levels were estimated in insulin dependent diabetics, non-insulin dependent diabetics and controls matched for number, sex and age. Significantly higher levels of these parameters were found in control group than in the other two groups. Statistically differences were ...

  7. Effect of Two-minute Application of 35% Sodium Ascorbate on Composite Bond Strength following Bleaching.

    Science.gov (United States)

    Ismail, Eman H; Kilinc, Evren; Hardigan, Patrick C; Rothrock, James K; Thompson, Jeffrey Y; Garcia-Godoy, Cristina

    2017-10-01

    The aim of this study is to assess the effect of 35% sodium ascorbate on microtensile bond strength of dentin immediately after bleaching with 35% hydrogen peroxide. A total of 25 sound human 3 rd molars were collected. Teeth were randomly divided into five groups for different treatments: Group I [bleaching + immediate bonding (i.e., restoration)], group II (bleaching + delayed bonding), group III (bleaching + sodium ascorbate + immediate bonding), group IV (bleaching + sodium ascorbate + delayed bonding), and group V (bonding only). After bleaching, but before bonding, groups II and IV were stored for 1 week in deionized water at 37°C. All samples were bonded using OptiBoned FL (Kerr) and Filtek Supreme (3M/ESPE). Teeth were sectioned into 1 × 1 mm 2 bars, and microtensile bond strength was tested with a universal testing machine (Instron 8841) at a cross-head speed of 0.5 mm/minute. Microtensile bond strength differed significantly across the five groups, with a significant reduction in microtensile bond strength observed for samples in group I relative to samples in any of the other treatment groups (p bleaching on composite bonding strength to dentin. The negative effects of bleaching on composite bonding can be neutralized by the application of the reversing agent sodium ascorbate thus, increasing the efficiency of clinic chair time. This is clinically relevant for those patients requiring restorative treatment immediately after in-office bleaching.

  8. Foliar application of ascorbic acid mitigates sodium chloride induced stress in eggplant (solanum melongena l.)

    International Nuclear Information System (INIS)

    Jan, S.; Hamayun, M.

    2016-01-01

    The current work was designed to test the effect of sodium chloride on germination, seedling establishment, vegetative growth, yield, chemical contents and ionic composition of eggplant. The consequences of foliar application of ascorbic acid (AA) on mitigation of adverse effects of sodium chloride were also tested. The seeds of Solanum melongena were germinated using NaCl (60 mM, 100 mM) and ascorbic acid (100 and 200 mM). High levels of salinity significantly affected the seed germination and seedling fresh and dry weights. Plants grown under salinity stress with foliar application of ascorbic acid showed significant increase in germination percentage and seedlings growth as compare to control plants. Sodium chloride stress showed adverse effects on plant height, root length, number of leaves, leaf area, fresh and dry biomass, total chlorophyll, carbohydrates and proteins as compared to untreated plants. The relative water content, electrolyte leakage were increased and Na+ and K+ ions balance was disturbed in different plant parts. Ascorbic acid (100 and 200ppm) enhanced all the growth parameters affected adversely by sodium chloride stress. (author)

  9. Reversal of clinical symptoms and radiographic abnormalities with protein restriction and ascorbic acid in alkaptonuria.

    NARCIS (Netherlands)

    Morava, E.; Kosztolanyi, G.Y.; Engelke, U.F.H.; Wevers, R.A.

    2003-01-01

    There is no definitive treatment protocol for alkaptonuria. A patient with alkaptonuria was treated with ascorbic acid (0.5 g/day) from the age of 4 years. He developed episodes of severe recurrent joint pain at 9.5 years of age after which a protein-restricted diet (1.3 g/kg/day) was started.

  10. Pyrophosphate levels strongly influence ascorbate and starch content in tomato fruit

    Directory of Open Access Journals (Sweden)

    Sonia eOsorio

    2013-08-01

    Full Text Available Ascorbate (vitamin C deficiency leads to low immunity, scurvy, and other human diseases and is therefore a global health problem. Given that plants are major ascorbate sources for humans, biofortification of this vitamin in our foodstuffs is of considerable importance. Ascorbate is synthetized by a number of alternative pathways: (i from the glycolytic intermediates D-glucose-6P (the key intermediates are GDP-D-mannose and L-galactose, (ii from the breakdown of the cell wall polymer pectin which uses the methyl ester of D-galacturonic acid as precursor and (iii from myo-inositol as precursor via myo-inositol oxygenase. We report here the engineering of fruit-specific overexpression of a bacterial pyrophosphatase, which hydrolyzes the inorganic pyrophosphate (PPi to orthophosphate (Pi. This strategy resulted in increased vitamin C levels up to 2.5 fold in ripe fruit as well as increasing in the major sugars, sucrose and glucose, yet decreasing the level of starch. When considered together, these finding indicate an intimate linkage between ascorbate and sugar biosynthesis in plants. Moreover, the combined data reveal the importance of PPi metabolism in tomato fruit metabolism and development.

  11. Stabilization of an injection preparation of technetium-99m MDP with ascorbic acid

    International Nuclear Information System (INIS)

    Lindelauf, F.M.P.; Sijtma, S.K.

    1983-01-01

    Tc-99m-labelled preparations for bone scanning are subject to oxidation in vitro. This results in bad scans with images of soft tissues as well. Three commercially available preparations were tested for stability after addition of ascorbic acid which effectively counteracts the oxidation by dissolved oxygen. (Auth.)

  12. Morphological assessment of bone mineralization in tibial metaphyses of ascorbic acid-deficient ODS rats.

    Science.gov (United States)

    Hasegawa, Tomoka; Li, Minqi; Hara, Kuniko; Sasaki, Muneteru; Tabata, Chihiro; de Freitas, Paulo Henrique Luiz; Hongo, Hiromi; Suzuki, Reiko; Kobayashi, Masatoshi; Inoue, Kiichiro; Yamamoto, Tsuneyuki; Oohata, Noboru; Oda, Kimimitsu; Akiyama, Yasuhiro; Amizuka, Norio

    2011-08-01

    Osteogenic disorder shionogi (ODS) rats carry a hereditary defect in ascorbic acid synthesis, mimicking human scurvy when fed with an ascorbic acid-deficient (aa-def) diet. As aa-def ODS rats were shown to feature disordered bone formation, we have examined the bone mineralization in this rat model. A fibrous tissue layer surrounding the trabeculae of tibial metaphyses was found in aa-def ODS rats, and this layer showed intense alkaline phosphatase activity and proliferating cell nuclear antigen-immunopositivity. Many osteoblasts detached from the bone surfaces and were characterized by round-shaped rough endoplasmic reticulum (rER), suggesting accumulation of malformed collagen inside the rER. Accordingly, fine, fragile fibrillar collagenous structures without evident striation were found in aa-def bones, which may result from misassembling of the triple helices of collagenous α-chains. Despite a marked reduction in bone formation, ascorbic acid deprivation seemed to have no effect on mineralization: while reduced in number, normal matrix vesicles and mineralized nodules could be seen in aa-def bones. Fine needle-like mineral crystals extended from these mineralized nodules, and were apparently bound to collagenous fibrillar structures. In summary, collagen mineralization seems unaffected by ascorbic acid deficiency in spite of the fine, fragile collagenous fibrils identified in the bones of our animal model.

  13. Functional role of ascorbic acid in bread-making | Dadzie-Mensah ...

    African Journals Online (AJOL)

    bread characteristics. Various levels of ascorbic acid and bromate were used in the bread production to compare critical functional properties of bread. The results showed that the specific volume of the loaves increased from 2.80 cm3/g ...

  14. The effect of ascorbic acid and propranolol on normal sleep and ...

    African Journals Online (AJOL)

    This study was designed to investigate the possible effects of ascorbic acid on open field locomotor activity and normal sleep in healthy adult rats and evaluate how these correlate with those of propranolol. MethodS: Eighty healthy adult Wistar rats of both sexes were divided into two groups of 40 animals each group.

  15. Effects of L-ascorbic acid and alpha-tocopherol on biochemical ...

    African Journals Online (AJOL)

    Background: The purpose of this study is to determine the effect of L-ascorbic acid and alpha-tocopherol as well as combination of these vitamins with or without exposure to physical exercise on intensity of lipid peroxidation, activity of xanthine oxidase, activity of total antioxidative system, concentration of glutathione, and ...

  16. The effects of ascorbic acid on salt induced alfalfa (Medicago sativa L.)

    African Journals Online (AJOL)

    Dr. J. T. Ekanem

    contribute to the high electrical conductivity of salt-affected lands3. ... the cellular mechanisms of the stress and its application at the .... Fig 2: Effect of salt and ascorbic acid on a) stem length, b) root length, c) root number, d) dry weight of ...

  17. Experience of application of ascorbate chitosan in the treatment of periodontal disease

    Directory of Open Access Journals (Sweden)

    Bulkina N.V.

    2013-09-01

    Full Text Available Aim. To study the clinical anti-inflammatory effect of gel form 8% ascorbate chitozan in treatment of inflammatory periodontal disease. Material and methods. The study included 30 patients: 10 patients with chronic catarrhal gingivitis, 10 patients with chronic generalized periodontitis mild and 10 moderate. Criteria for inclusion of patients in the study: age between 18 and 45 years old, reliable diagnosis, informed consent of the patient. Case history of the disease duration from one to five years. The state of periodontal tissue was evaluated clinically and radiographically by intraoral radiography. According to treatment methods patients were divided into groups: group 1 underwent traditional treatment, group 2 was treated with the use of applications of 8% of ascorbate chitosan on the area of papillae and marginal gingiva with the capture of 1-2 cm of the mucous membrane of the alveolar process. The duration of treatment was 15 minutes daily for 10 days. Results. The patterns suggest that the therapeutic effect of ascorbate chitazan caused prolonged sanation of periodontal pockets due to the antibacterial activity of chitazan. Conclusion. The data show that regeneration in patients who have a combined treatment included ascorbate chitosan has been more rapid and complete than similar processes in periodontal patients treated in a traditional way.

  18. Copper/ascorbic acid dyad as a catalytic system for selective aerobic oxidation of amines

    Czech Academy of Sciences Publication Activity Database

    Šrogl, Jiří; Voltrová, Svatava

    2009-01-01

    Roč. 11, č. 4 (2009), s. 843-845 ISSN 1523-7060 Institutional research plan: CEZ:AV0Z40550506 Keywords : copper * ascorbic acid * oxidative deamination Subject RIV: CC - Organic Chemistry Impact factor: 5.420, year: 2009

  19. Effect of Combined Intake of Garcinia Kola and Ascorbic Acid on ...

    African Journals Online (AJOL)

    This study was carried out to determine the effect of combined intake of Garcinia kola and Ascorbic acid on Intraocular pressure (IOP) of normotensive Nigerians. A total of one hundred and sixty (n= 160) parcipants, males, and females within the age range of 18-50 years (Mean age = 29.29± 8.74) were used for this study.

  20. Antinociceptive Properties of Ascorbic Acid: Evidence for the Mechanism of Action

    Directory of Open Access Journals (Sweden)

    Zeraati

    2014-09-01

    Full Text Available Background Ascorbic acid is amongst important water-soluble vitamins and when used orally in high-doses it has been observed to relieve pain and reduce opioid use in patients. However no controlled trial has compared the antinociceptive effects of ascorbic acid with other analgesic groups on animal models, and investigated the involved mechanisms. Objectives In the present study, the antinociceptive effect of vitamin C on male mice was investigated and compared with morphine and diclofenac. Also, possible mechanisms were assayed. Materials and Methods Male albino mice were used in this study. Antinociception was measured using the writhing test, tail flick and formalin tests. Ascorbic acid was used in three doses (30, 150 and 300 mg/kg, IP and compared with the antinociceptive effects of 10 mg/kg of morphine as an opioid analgesic agent and 5-10 mg/kg of diclofenac as a nonsteroidal anti-inflammatory drug (NSAID analgesic agent.The antinociceptive effect of ascorbic acid (300 mg/kg was compared before and after treatment with naloxone (4 mg/kg, ondansetron (0.5 mg/kg, atropine (5 mg/kg and metoclopramide (1 mg/kg in the writhing test. Results Vitamin C caused dose-dependent antinociceptive effects in acetic acid writhing test (P < 0.05. It had no significant effect in the tail flick test. Meanwhile, vitamin C in high doses reduced pain in the second phase of the formalin test (P < 0.05. Morphine had higher nociceptive effects in comparison to ascorbic acid in the writhing test (P < 0.05. In the second phase of the formalin test the antinociceptive effects of vitamin C (300 mg/kg was not significantly different with morphine at dose of 10 mg/kg. There was not significant difference between vitamin C (300 mg/kg and diclofenac (10 mg/kg in the second phase of the formalin test. Metoclopramide and ondansetrone reduced the antinociceptive effects of vitamin C. Conclusions The results obtained from the acetic acid induced writhing test and second

  1. Improved control of exogenous attention in action video game players

    Directory of Open Access Journals (Sweden)

    Matthew S Cain

    2014-02-01

    Full Text Available Action video game players have demonstrated a number of attentional advantages over non-players. Here, we propose that many of those benefits might be underpinned by improved control over exogenous (i.e., stimulus-driven attention. To test this we used an anti-cuing task, in which a sudden-onset cue indicated that the target would likely appear in a separate location on the opposite side of the fixation point. When the time between the cue onset and the target onset was short (40 ms, non-players (nVGPs showed a typical exogenous attention effect. Their response times were faster to targets presented at the cued (but less probable location compared with the opposite (more probable location. Video game players (VGPs, however, were less likely to have their attention drawn to the location of the cue. When the onset asynchrony was long (600 ms, VGPs and nVGPs were equally able to endogenously shift their attention to the likely (opposite target location. In order to rule out processing-speed differences as an explanation for this result, we also tested VGPs and nVGPs on an attentional blink task. In a version of the attentional blink task that minimized demands on task switching and iconic memory, VGPs and nVGPs did not differ in second target identification performance (i.e., VGPs had the same magnitude of attentional blink as nVGPs, suggesting that the anti-cuing results were due to flexible control over exogenous attention rather than to more general speed-of-processing differences.

  2. Exogenous attention enhances 2nd-order contrast sensitivity

    Science.gov (United States)

    Barbot, Antoine; Landy, Michael S.; Carrasco, Marisa

    2011-01-01

    Natural scenes contain a rich variety of contours that the visual system extracts to segregrate the retinal image into perceptually coherent regions. Covert spatial attention helps extract contours by enhancing contrast sensitivity for 1st-order, luminance-defined patterns at attended locations, while reducing sensitivity at unattended locations, relative to neutral attention allocation. However, humans are also sensitive to 2nd-order patterns such as spatial variations of texture, which are predominant in natural scenes and cannot be detected by linear mechanisms. We assess whether and how exogenous attention—the involuntary and transient capture of spatial attention—affects the contrast sensitivity of channels sensitive to 2nd-order, texture-defined patterns. Using 2nd-order, texture-defined stimuli, we demonstrate that exogenous attention increases 2nd-order contrast sensitivity at the attended location, while decreasing it at unattended locations, relative to a neutral condition. By manipulating both 1st- and 2nd-order spatial frequency, we find that the effects of attention depend both on 2nd-order spatial frequency of the stimulus and the observer’s 2nd-order spatial resolution at the target location. At parafoveal locations, attention enhances 2nd-order contrast sensitivity to high, but not to low 2nd-order spatial frequencies; at peripheral locations attention also enhances sensitivity to low 2nd-order spatial frequencies. Control experiments rule out the possibility that these effects might be due to an increase in contrast sensitivity at the 1st-order stage of visual processing. Thus, exogenous attention affects 2nd-order contrast sensitivity at both attended and unattended locations. PMID:21356228

  3. On the spatial specificity of audiovisual crossmodal exogenous cuing effects.

    Science.gov (United States)

    Lee, Jae; Spence, Charles

    2017-06-01

    It is generally-accepted that the presentation of an auditory cue will direct an observer's spatial attention to the region of space from where it originates and therefore facilitate responses to visual targets presented there rather than from a different position within the cued hemifield. However, to date, there has been surprisingly limited evidence published in support of such within-hemifield crossmodal exogenous spatial cuing effects. Here, we report two experiments designed to investigate within- and between-hemifield spatial cuing effects in the case of audiovisual exogenous covert orienting. Auditory cues were presented from one of four frontal loudspeakers (two on either side of central fixation). There were eight possible visual target locations (one above and another below each of the loudspeakers). The auditory cues were evenly separated laterally by 30° in Experiment 1, and by 10° in Experiment 2. The potential cue and target locations were separated vertically by approximately 19° in Experiment 1, and by 4° in Experiment 2. On each trial, the participants made a speeded elevation (i.e., up vs. down) discrimination response to the visual target following the presentation of a spatially-nonpredictive auditory cue. Within-hemifield spatial cuing effects were observed only when the auditory cues were presented from the inner locations. Between-hemifield spatial cuing effects were observed in both experiments. Taken together, these results demonstrate that crossmodal exogenous shifts of spatial attention depend on the eccentricity of both the cue and target in a way that has not been made explicit by previous research. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Exogenous lipoid pneumonia: HRCT, MR, and pathologic findings

    International Nuclear Information System (INIS)

    Laurent, F.; Philippe, J.C.; Vergier, B.; Granger-Veron, B.; Darpeix, B.; Vergeret, J.; Blanc, P.; Velly, J.F.

    1999-01-01

    The objective of this study was to describe high-resolution CT (HRCT) and MR findings of exogenous lipoid pneumonia and to correlate them with pathologic findings. A retrospective review of the medical records of our institution revealed seven patients with a diagnosis of lipoid pneumonia based on clinical data, chest films, bronchoalveolar lavage, and follow-up. Both HRCT and MR imaging were reviewed by two readers. Pathologic examination of the resected specimen or surgical biopsies were also reviewed in the four available cases. The HRCT findings were pulmonary consolidations (n = 6) with fatty (n = 3) or unspecific but low attenuation values (n = 3), areas of ground-glass opacities (n = 5), septal lines, and centrilobular interstitial thickening (n = 5). In five of the seven cases, a crazy-paving pattern of various spread was also present, either isolated (n = 1) or surrounding a pulmonary consolidation. In two cases traction bronchiectasis and cystic changes consistent with fibrosis were seen. At MR imaging (n = 2) a pulmonary consolidation of high signal intensity on T1-weighted image consistent with lipid content was present in one case. Pathologic examination (n = 4) showed the coexistence of lobules with lesions of various ages, sometimes in contiguous lobules, within the same patient. Recent lesions were those with alveolar fill-in by spumous macrophages and almost normal alveolar walls and septae. In more advanced lesions, lobules were filled in with larger vacuoles often surrounded by inflammatory infiltrates of alveolar walls, bronchiolar walls, and septa. The oldest lesions were characterized by fibrosis and parenchymal distortion around large lipid-containing vacuoles. The HRCT findings reflect pathologic findings in exogenous lipoid pneumonia. Although non-specific, consolidation areas of low attenuation values and crazy-paving pattern are frequently associated in exogenous lipoid pneumonia and are indicative of the diagnosis. (orig.)

  5. Offshoring as an Exogenous Shock to the Services Production System

    DEFF Research Database (Denmark)

    Brandl, Kristin; Mol, Michael; Petersen, Bent

    Production of services involves three key elements, an output for the client, resources of a provider and task execution. Offshoring of services acts as an exogenous shock to such a production system. Using multiple case methodology we investigate how task output, execution, and resources change...... as a consequence of offshoring and particularly how these elements are realigned. The cases reveal substantial managerial challenges in the alignment process prompted by a relocation of service task execution to an emerging economy. In particular, we find that instead of some set of capabilities that proactively...

  6. Volumetric and viscometric studies of amino acids in L-ascorbic acid aqueous solutions at T = (293.15 to 323.15) K

    International Nuclear Information System (INIS)

    Jiang, Xiaofeng; Zhu, Chunying; Ma, Youguang

    2014-01-01

    Graphical abstract: The densities and viscosities of L-alanine in L-ascorbic acid aqueous solutions at T = 293.15 K. Highlights: • Densities and viscosities of five amino acids in L-ascorbic acid aqueous solutions were measured. • Based on the experimental data, a series of volumetric and viscometric parameters were calculated. • The group additivity analysis has been applied to analyze the V φ 0 and B-coefficients. -- Abstract: Densities and viscosities of glycine, L-alanine, L-valine, L-threonine and L-arginine in aqueous solutions of (0.0, 0.1, 0.2, 0.3 and 0.4) mol · kg −1 L-ascorbic acid have been measured at T = (293.15, 303.15, 313.15 and 323.15) K under atmospheric pressure. The apparent molar volumes (V φ ), limiting partial molar volumes (V φ 0 ), limiting partial molar volumes of transfer (Δ tr V φ 0 ) and limiting partial molar expansibilities (E 2 0 ) were computed by densities. The extended Jones–Dole equation was used to correlate the viscosities in order to obtain viscosity B-coefficients and the free energies of activation per mole of solvent (Δμ 1 0≠ ) and solute (Δμ 2 0≠ ) were also calculated. The contributions of zwitterionic end group (NH 3 + , COO − ), CH 2 group, OH group and CNHNHNH 2 group to V φ 0 and viscosity B-coefficients were obtained through the group additivity analysis

  7. Interactive effects of herbicide and enhanced UV-B on growth, oxidative damage and the ascorbate-glutathione cycle in two Azolla species.

    Science.gov (United States)

    Prasad, Sheo Mohan; Kumar, Sushil; Parihar, Parul; Singh, Rachana

    2016-11-01

    A field experiment was conducted to investigate the impact of alone and combined exposures of herbicide pretilachlor (5, 10 and 20μgml(-1)) and enhanced UV-B radiation (UV-B1; ambient +2.2kJm(-2) day(-1) and UV-B2; ambient +4.4kJm(-2) day(-1)) on growth, oxidative stress and the ascorbate-glutathione (AsA-GSH) cycle in two agronomically important Azolla spp. viz., Azolla microphylla and Azolla pinnata. Decreased relative growth rate (RGR) in both the species under tested stress could be linked to enhanced oxidative stress, thus higher H2O2 accumulation was observed, that in turn might have caused severe damage to lipids and proteins, thereby decreasing membrane stability. The effects were exacerbated when spp. were exposed to combined treatments of enhanced UV-B and pretilachlor. Detoxification of H2O2 is regulated by enzymes/metabolites of AsA-GSH cycle such as ascorbate peroxidase (APX) and glutathione reductase (GR) activity that were found to be stimulated. While, dehydroascorabte reductase (DHAR) activity, and the amount of metabolites: ascorbate (AsA), glutathione (GSH) and ratios of reduced/oxidized AsA (AsA/DHA) and GSH (GSH/GSSG), showed significant reduction with increasing doses of both the stressors, either applied alone or in combination. Glutathione-S-transferase (GST), an enzyme involved in scavenging of xenobiotics, was found to be stimulated under the tested stress. This study suggests that decline in DHAR activity and in AsA/DHA ratio might have led to enhanced H2O2 accumulation, thus decreased RGR was noticed under tested stress in both the species and the effect was more pronounced in A. pinnata. Owing to better performance of AsA-GSH cycle in A. microphylla, this study substantiates the view that A. microphylla is more tolerant than A. pinnata. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Comparison of radioprotective effects of caffeine and ascorbic acid in male mice

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Kyu; Kim, Ji Hyang; Lee, Byoung Hun [KAERI, Taejon (Korea, Republic of); Yoon, Yong Dal [Hanyang Univ., Seoul (Korea, Republic of)

    2003-04-01

    The oxygen effect in radiation biology is well known. Since oxygen enhances radiation-induced biological damage, antioxidants should be radioprotectors. Ascorbic acid (vitamin C) or caffeine is an essential component in the diet of humans and a small range of other mammals. Radioprotective effects of vitamin C have been demonstrated in certain cells and animals, which would result from scavenging free radicals. Caffeine is the main psychoactive ingredient of coffee, tea, even coke with a high frequency of concurrent use in humans. Caffeine has been recently reported as a scavenger of hydroxyl radical in millimolar levels and a potently radioprotector in a chronically exposed rodent. This study investigates functional radioprotection of caffeine and ascorbic acid against gamma irradiation in male mice. Eight-week-old male C57BL/6N mice were irradiated with 6.5 Gy. A caffeine treated group was administered with 80 mg/kg body weight by i.p injection, a single exposure 1 hour before irradiation. Ascorbic acid was administered 330 mg/liter in drinking water through all the experimental period. The remaining mice were kept as sham controls. After collecting a serum from the experimental mice 6 hr after irradiation, qualitative analysis of testosterone was performed by means of radioimmunoassay (RIA). For histological investigation, testes were removed 1 week after irradiation and fixed in NBF. Fixed testes were processed for paraffin sections and stained by H-E. The circulating testosterone significantly decreased in all irradiated groups. The harmful effect of radiation on the body and organ weight and the appearance of semiferous tubules were significantly improved in the caffeine - or ascorbic acid-treated group. In conclusion, caffeine and ascorbic acid protected spermatogenesis from impairment against gamma radiation, acting as a radioprotector.

  9. Ascorbic acid supplementation diminishes microparticle elevations and neutrophil activation following SCUBA diving.

    Science.gov (United States)

    Yang, Ming; Barak, Otto F; Dujic, Zeljko; Madden, Dennis; Bhopale, Veena M; Bhullar, Jasjeet; Thom, Stephen R

    2015-08-15

    Predicated on evidence that diving-related microparticle generation is an oxidative stress response, this study investigated the role that oxygen plays in augmenting production of annexin V-positive microparticles associated with open-water SCUBA diving and whether elevations can be abrogated by ascorbic acid. Following a cross-over study design, 14 male subjects ingested placebo and 2-3 wk later ascorbic acid (2 g) daily for 6 days prior to performing either a 47-min dive to 18 m of sea water while breathing air (∼222 kPa N2/59 kPa O2) or breathing a mixture of 60% O2/balance N2 from a tight-fitting face mask at atmospheric pressure for 47 min (∼40 kPa N2/59 kPa O2). Within 30 min after the 18-m dive in the placebo group, neutrophil activation, and platelet-neutrophil interactions occurred, and the total number of microparticles, as well as subgroups bearing CD66b, CD41, CD31, CD142 proteins or nitrotyrosine, increased approximately twofold. No significant elevations occurred among divers after ingesting ascorbic acid, nor were elevations identified in either group after breathing 60% O2. Ascorbic acid had no significant effect on post-dive intravascular bubble production quantified by transthoracic echocardiography. We conclude that high-pressure nitrogen plays a key role in neutrophil and microparticle-associated changes with diving and that responses can be abrogated by dietary ascorbic acid supplementation. Copyright © 2015 the American Physiological Society.

  10. EFFECT OF PHYSICAL EXERCISE ON LIPID PEROXIDATION AND ANTIOXIDANT ASCORBIC ACID DEFENSE

    Directory of Open Access Journals (Sweden)

    Ljiljana M. Popović

    2006-06-01

    Full Text Available Strenuous exercises greatly increase oxygen consumption in the whole body, especially in skeletal muscles. Large part of oxygen consumption is reduced to H2O and ATP, but smaller part (2-5% results in an increased leakage of electrons from the mitochondrial respiratory chain, forming various reactive oxygen species ─ ROS (O2˙¯, H2O2 i OH˙. These free radicals are capable of triggering a chain of damaging biochemical and physiological reactions (oxidative stress, lipid peroxidation,as a base for skeletal muscles damage after exercise. MDA (malondialdehide is a marker of exercise induced lipid peroxidation process. L–ascorbic acid is a major aqueous-phase antioxidant. To estimate antioxidant role of ascorbic acid we use rate between dehidroascorbate and ascorbate. In this paper those markers were determinated in 30 students, in rest and after treadmill running protocol (Bruce Treadmill Protocol. It was found that after the treadmill test , plasma MDA level had increased from 3,04 to 4,39 μM/L. Plasma ascorbic acid was also found to be higher after the treadmill test comparing to rest level (from 55,4 to 67,6 μM/L. DHA/A level in rest was 1,62 and after treadmill test it increased to 2,05. These results suggests that strenuous exercise increased process of lipid peroxidation, but in the same time increased ascorbic acid level in plasma and DHA/A rate indicates stronger antioxidant defense system.

  11. Comparison of radioprotective effects of caffeine and ascorbic acid in male mice

    International Nuclear Information System (INIS)

    Kim, Jin Kyu; Kim, Ji Hyang; Lee, Byoung Hun; Yoon, Yong Dal

    2003-01-01

    The oxygen effect in radiation biology is well known. Since oxygen enhances radiation-induced biological damage, antioxidants should be radioprotectors. Ascorbic acid (vitamin C) or caffeine is an essential component in the diet of humans and a small range of other mammals. Radioprotective effects of vitamin C have been demonstrated in certain cells and animals, which would result from scavenging free radicals. Caffeine is the main psychoactive ingredient of coffee, tea, even coke with a high frequency of concurrent use in humans. Caffeine has been recently reported as a scavenger of hydroxyl radical in millimolar levels and a potently radioprotector in a chronically exposed rodent. This study investigates functional radioprotection of caffeine and ascorbic acid against gamma irradiation in male mice. Eight-week-old male C57BL/6N mice were irradiated with 6.5 Gy. A caffeine treated group was administered with 80 mg/kg body weight by i.p injection, a single exposure 1 hour before irradiation. Ascorbic acid was administered 330 mg/liter in drinking water through all the experimental period. The remaining mice were kept as sham controls. After collecting a serum from the experimental mice 6 hr after irradiation, qualitative analysis of testosterone was performed by means of radioimmunoassay (RIA). For histological investigation, testes were removed 1 week after irradiation and fixed in NBF. Fixed testes were processed for paraffin sections and stained by H-E. The circulating testosterone significantly decreased in all irradiated groups. The harmful effect of radiation on the body and organ weight and the appearance of semiferous tubules were significantly improved in the caffeine - or ascorbic acid-treated group. In conclusion, caffeine and ascorbic acid protected spermatogenesis from impairment against gamma radiation, acting as a radioprotector

  12. Exogenous trehalose improves growth under limiting nitrogen through upregulation of nitrogen metabolism.

    Science.gov (United States)

    Lin, Yingchao; Zhang, Jie; Gao, Weichang; Chen, Yi; Li, Hongxun; Lawlor, David W; Paul, Matthew J; Pan, Wenjie

    2017-12-19

    The trehalose (Tre) pathway has strong effects on growth and development in plants through regulation of carbon metabolism. Altering either Tre or trehalose 6-phosphate (T6P) can improve growth and productivity of plants as observed under different water availability. As yet, there are no reports of the effects of modification of Tre orT6P on plant performance under limiting nutrition. Here we report that nitrogen (N) metabolism is positively affected by exogenous application of Tre in nitrogen-deficient growing conditions. Spraying foliage of tobacco (Nicotiana tabacum) with trehalose partially alleviated symptoms of nitrogen deficiency through upregulation of nitrate and ammonia assimilation and increasing activities of nitrate reductase (NR), glycolate oxidase (GO), glutamine synthetase (GS) and glutamine oxoglutarate aminotransferase (GOGAT) with concomitant changes in ammonium (NH 4 + ) and nitrate (NO 3 - ) concentrations, glutamine and amino acids. Chlorophyll and total nitrogen content of leaves and rates of photosynthesis were increased compared to nitrogen-deficient plants without applied Tre. Total plant biomass accumulation was also higher in Tre -fed nitrogen-deficient plants, with a smaller proportion of dry weight partitioned to roots, compared to nitrogen-deficient plants without applied Tre. Consistent with higher nitrogen assimilation and growth, Tre application reduced foliar starch. Minimal effects of Tre feeding were observed on nitrogen-sufficient plants. The data show, for the first time, significant stimulatory effects of exogenous Tre on nitrogen metabolism and growth in plants growing under deficient nitrogen. Under such adverse conditions metabolism is regulated for survival rather than productivity. Application of Tre can alter this regulation towards maintenance of productive functions under low nitrogen. This has implications for considering approaches to modifying the Tre pathway for to improve crop nitrogen-use efficiency and

  13. Differential effects of 10-Hz and 40-Hz transcranial alternating current stimulation (tACS) on endogenous versus exogenous attention.

    Science.gov (United States)

    Hopfinger, Joseph B; Parsons, Jonathan; Fröhlich, Flavio

    2017-04-01

    Previous electrophysiological studies implicate both alpha (8-12 Hz) and gamma (>30 Hz) neural oscillations in the mechanisms of selective attention. Here, participants preformed two separate visual attention tasks, one endogenous and one exogenous, while transcranial alternating current stimulation (tACS), at 10 Hz, 40 Hz, or sham, was applied to the right parietal lobe. Our results provide new evidence for the roles of gamma and alpha oscillations in voluntary versus involuntary shifts of attention. Gamma (40 Hz) stimulation resulted in improved disengagement from invalidly cued targets in the endogenous attention task, whereas alpha stimulation (10 Hz) had no effect on endogenous attention, but increased the exogenous cuing effect. These findings agree with previous studies suggesting that right inferior parietal regions may be especially important for the disengagement of attention, and go further to provide details about the specific type of oscillatory neural activity within that brain region that is differentially involved in endogenous versus exogenous attention. Our results also have potential implications for the plasticity and training of attention systems.

  14. Transcriptional profile of genes involved in ascorbate glutathione cycle in senescing leaves for an early senescence leaf (esl) rice mutant.

    Science.gov (United States)

    Li, Zhaowei; Su, Da; Lei, Bingting; Wang, Fubiao; Geng, Wei; Pan, Gang; Cheng, Fangmin

    2015-03-15

    To clarify the complex relationship between ascorbate-glutathione (AsA-GSH) cycle and H2O2-induced leaf senescence, the genotype-dependent difference in some senescence-related physiological parameters and the transcript levels and the temporal patterns of genes involved in the AsA-GSH cycle during leaf senescence were investigated using two rice genotypes, namely, the early senescence leaf (esl) mutant and its wild type. Meanwhile, the triggering effect of exogenous H2O2 on the expression of OsAPX genes was examined using detached leaves. The results showed that the esl mutant had higher H2O2 level than its wild type at the initial stage of leaf senescence. At transcriptional level, the association of expression of various genes involved in the AsA-GSH cycle with leaf senescence was isoform dependent. For OsAPXs, the transcripts of two cytosolic OsAPX genes (OsAPX1 and OsAPX2), thylakoid-bound OsAPX8, chloroplastic OsAPX7 and peroxisomal OsAPX4 exhibited remarkable genotype-dependent variation in their expression levels and temporal patterns during leaf senescence, there were significantly increasing transcripts of OsAXP1 and OsAPX7, severely repressed transcripts of OsAPX4 and OsAPX8 for the esl rice at the initial leaf senescence. In contrast, the repressing transcript of OsAPX8 was highly sensitive to the increasing H2O2 level in the senescing rice leaves, while higher H2O2 concentration resulted in the enhancing transcripts of two cytosolic OsAPX genes, OsAPX7 transcript was greatly variable with different H2O2 concentrations and incubating duration, suggesting that the different OsAPXs isoforms played a complementary role in perceiving and scavenging H2O2 accumulation at various H2O2 concentrations during leaf senescence. Higher H2O2 level, increased AsA level, higher activities of APX and glutathione reductase (GR), and relatively stable GSH content during the entire sampling period in the leaves of esl mutant implied that a close interrelationship existed

  15. Effects of Pre-Converted Nitrite from Red Beet and Ascorbic Acid on Quality Characteristics in Meat Emulsions

    Science.gov (United States)

    Kim, Hyun-Wook; Hwang, Ko-Eun

    2017-01-01

    We investigated the effects of fermented red beet extract and ascorbic acid on color development in meat emulsions. The pH of meat emulsions containing red beet extract decreased with an increase in the amount of extract added. The redness of the treated meat emulsions was higher than that of the control with no added nitrite or fermented red beet extract (pmeat emulsions treated with fermented red beet extract only was lower than in that treated with both fermented red beet extract and ascorbic acid (pmeat emulsions treated with fermented red beet extract were higher than in that treated with both fermented red beet extract and ascorbic acid (pmeat emulsions tested. Treatment T2, containing nitrite and ascorbic acid, had the highest overall acceptability score (pnitrite from red beet extract and 0.05% ascorbic acid (p>0.05). The residual nitrite content of the meat emulsions treated with ascorbic acid was lower than in those treated without ascorbic acid (pnitrite for the stability of color development in meat emulsions. PMID:28515652

  16. Ascorbic acid levels in human tears after photorefractive keratectomy, transepithelial photorefractive keratectomy, and laser in situ keratomileusis.

    Science.gov (United States)

    Bilgihan, A; Bilgihan, K; Toklu, Y; Konuk, O; Yis, O; Hasanreisoğlu, B

    2001-04-01

    To investigate the level of ascorbic acid in human tear fluid after photorefractive keratectomy (PRK), transepithelial PRK, and laser in situ keratomileusis (LASIK). Departments of Ophthalmology and Biochemistry, School of Medicine, Gazi University, Ankara, Turkey. Twenty patients (7 women and 13 men) were included in this study. Traditional PRK with epithelial scraping by a blunt spatula followed by surface ablation (7 eyes), transepithelial PRK (7 eyes), or LASIK (6 eyes) was performed. Tears were collected preoperatively and 1 and 5 days postoperatively. Ascorbic acid levels were measured using 2-4 dinitrophenylhydrazine. Ascorbic acid levels in the tear fluid were decreased significantly 1 day after PRK, transepithelial PRK, and LASIK (P <.05). On the fifth day, the ascorbic acid levels were significantly lower than preoperatively in all groups. After PRK, transepithelial PRK, and LASIK, the ascorbic acid levels of the tear fluid decreased significantly. Because ascorbic acid is the major scavenger of superoxide radicals in tears, topical ascorbic acid therapy may help eliminate the harmful effect of free radicals from excimer laser surgery.

  17. EFFECT OF ASCORBIC ACID ON THE RIGHT AND LEFT CORONARY ARTERIES OF MALE RABBITS FED WITH HIGH-CHOLESTEROL DIET

    Directory of Open Access Journals (Sweden)

    Gholamreza Dashti

    2010-12-01

    Full Text Available   Abstract INTRODUCTION: Atherosclerosis and cardiovascular diseases are the most common causes of death in western countries. The beneficial effect of ascorbic acid on various organs has been reported. The present study was conducted to determine the effect of ascorbic acid on the right and left coronary arteries of male rabbits fed with high-cholesterol diet. methods: Twenty white male rabbits (mean weight: 950 g were weighed and randomly divided into two groups. For 40 days, group 1 (n=10 was given a high-cholesterol (1% diet, group 2 (n=10 was fed with a high-cholesterol diet and ascorbic acid (100 mg/kg. Then both of the groups were weighed and the animals were sacrificed. The right and left coronary arteries were dissected and then fixation, tissue processing, histological sectioning and H & E staining were carried out and sections were studied by light microscopy. The results were analyzed by using the Mann Whitney test. results: Group 2 which received ascorbic acid had no fatty streaks in their coronary arteries. Significant difference in mean weight was observed before and after the diet in both groups (P<0.05. CONCLUSIONS: Histopathological study of the coronary arteries showed that the rabbits which received ascorbic acid diet did not develop fatty streaks. Thus ascorbic acid exerts an apparently inhibitory effect on fatty streak formation and may slow down or prevent atherosclerosis by countering the side effects of a high-fat meal.     Keywords: Ascorbic acid, cholesterol, coronary arteries.

  18. Understanding the Effects of Users' Behaviors on Effectiveness of Different Exogenous Regulatory Common Pool Resource Management Institutions

    Science.gov (United States)

    Madani, K.; Dinar, A.

    2013-12-01

    Tragedy of the commons is generally recognized as one of the possible destinies for common pool resources (CPRs). To avoid the tragedy of the commons and prolonging the life of CPRs, users may show different behavioral characteristics and use different rationales for CPR planning and management. Furthermore, regulators may adopt different strategies for sustainable management of CPRs. The effectiveness of different regulatory exogenous management institutions cannot be evaluated through conventional CPR models since they assume that either users base their behavior on individual rationality and adopt a selfish behavior (Nash behavior), or that the users seek the system's optimal solution without giving priority to their own interests. Therefore, conventional models fail to reliably predict the outcome of CPR problems in which parties may have a range of behavioral characteristics, putting them somewhere in between the two types of behaviors traditionally considered. This work examines the effectiveness of different regulatory exogenous CPR management institutions through a user-based model (as opposed to a system-based model). The new modeling framework allows for consideration of sensitivity of the results to different behavioral characteristics of interacting CPR users. The suggested modeling approach is applied to a benchmark groundwater management problem. Results indicate that some well-known exogenous management institutions (e.g. taxing) are ineffective in sustainable management of CPRs in most cases. Bankruptcy-based management can be helpful, but determination of the fair level of cutbacks remains challenging under this type of institution. Furthermore, some bankruptcy rules such as the Constrained Equal Award (CEA) method are more beneficial to wealthier users, failing to establish social justice. Quota-based and CPR status-based management perform as the most promising and robust regulatory exogenous institutions in prolonging the CPR's life and

  19. Does exogenous carbon extend the realized niche of canopy lichens? Evidence from sub-boreal forests in British Columbia.

    Science.gov (United States)

    Campbell, Jocelyn; Bengtson, Per; Fredeen, Arthur L; Coxson, Darwyn S; Prescott, Cindy E

    2013-05-01

    Foliose lichens with cyanobacterial bionts (bipartite and tripartite) form a distinct assemblage of epiphytes strongly associated with humid microclimatic conditions in inland British Columbia. Previous research showed that these cyano- and cephalolichen communities are disproportionately abundant and species-rich on conifer saplings beneath Populus compared to beneath other tree species. More revealing, lichens with cyanobacterial bionts were observed beneath Populus even in stands that did not otherwise support them. We experimentally test the hypothesis that this association is due to the interception of glucose-rich nectar that is exuded from Populus extra-floral nectaries (EFN). Using CO2 flux measurements and phospholipid fatty acid (PLFA) analysis with experimental applications of 13C6-labeled glucose, we demonstrate that cyano- and cephalolichens have a strong respiratory response to glucose. Lichens treated with glucose had lower net photosynthesis and higher establishment rates than control thalli. Furthermore, lichens with cyanobacterial bionts rapidly incorporate exogenous 13C into lichen fatty acid tissues. A large proportion of the 13C taken up by the lichens was incorporated into fungal biomarkers, suggesting that the mycobiont absorbed and assimilated the majority of applied 13C6 glucose. Our observations suggest that both cyanolichens and cephalolichens may utilize an exogenous source of glucose, made available by poplar EFNs. The exogenous C may enable these lichens to become established by providing a source of C for fungal respiration despite drought-induced inactivity of the cyanobacterial partner. As such, the mycobiont may adopt an alternative nutritional strategy, using available exogenous carbon to extend its realized niche.

  20. Applied Electromagnetics

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, H; Marinova, I; Cingoski, V [eds.

    2002-07-01

    These proceedings contain papers relating to the 3rd Japanese-Bulgarian-Macedonian Joint Seminar on Applied Electromagnetics. Included are the following groups: Numerical Methods I; Electrical and Mechanical System Analysis and Simulations; Inverse Problems and Optimizations; Software Methodology; Numerical Methods II; Applied Electromagnetics.

  1. Applied Electromagnetics

    International Nuclear Information System (INIS)

    Yamashita, H.; Marinova, I.; Cingoski, V.

    2002-01-01

    These proceedings contain papers relating to the 3rd Japanese-Bulgarian-Macedonian Joint Seminar on Applied Electromagnetics. Included are the following groups: Numerical Methods I; Electrical and Mechanical System Analysis and Simulations; Inverse Problems and Optimizations; Software Methodology; Numerical Methods II; Applied Electromagnetics

  2. The interactions of multisensory integration with endogenous and exogenous attention

    Science.gov (United States)

    Tang, Xiaoyu; Wu, Jinglong; Shen, Yong

    2016-01-01

    Stimuli from multiple sensory organs can be integrated into a coherent representation through multiple phases of multisensory processing; this phenomenon is called multisensory integration. Multisensory integration can interact with attention. Here, we propose a framework in which attention modulates multisensory processing in both endogenous (goal-driven) and exogenous (stimulus-driven) ways. Moreover, multisensory integration exerts not only bottom-up but also top-down control over attention. Specifically, we propose the following: (1) endogenous attentional selectivity acts on multiple levels of multisensory processing to determine the extent to which simultaneous stimuli from different modalities can be integrated; (2) integrated multisensory events exert top-down control on attentional capture via multisensory search templates that are stored in the brain; (3) integrated multisensory events can capture attention efficiently, even in quite complex circumstances, due to their increased salience compared to unimodal events and can thus improve search accuracy; and (4) within a multisensory object, endogenous attention can spread from one modality to another in an exogenous manner. PMID:26546734

  3. Exogenic geomorphic processes dynamics at the Black Sea coast, Russia

    Science.gov (United States)

    Kuznetsova, Yulia; Tsvetkova, Daria

    2017-04-01

    Nowadays there is an obvious grow of anthropogenic load going on in many areas worldwide. Under such conditions, intensive activation of a number of exogenic geomorphic processes may be observed. Moreover, if natural environment is aggressive itself their dynamics and rates may reach enormous values. Our work is conducted at the Black Sea coast, known for its mountainous topography, wet subtropical climate and intensive anthropogenic development (especially during the last decade due to the recent Olympic games). We chose two key basins near Sochi, Russia to study a number of presented exogenic processes, including rill, gully and channel erosion, weathering, suffusion and piping, soil creep. A set of field study methods is used to monitor the processes dynamics since 2005 (and late 1970s for soil creep). In addition, soil erosion rates and landslide susceptibility were modelled to get information of the watersheds dynamics. This is ongoing work, but the results of the passed period of observations will be resented. Special attention is paid to the processes connectivity and their input into sediment redistribution over the river basins.

  4. Exogenous Testosterone Enhances the Reactivity to Social Provocation in Males

    Directory of Open Access Journals (Sweden)

    Lisa Wagels

    2018-03-01

    Full Text Available Testosterone affects human social behavior in various ways. While testosterone effects are generally associated with muscular strength and aggressiveness, human studies also point towards enhanced status–seeking motives after testosterone administration. The current study tested the causal influence of exogenous testosterone on male behavior during a competitive provocation paradigm. In this double blind, randomized, placebo (PL-controlled study, 103 males were assigned to a PL or testosterone group receiving a colorless PL or testosterone gel. To induce provocation, males played a rigged reaction time game against an ostensible opponent. When participants lost, the opponent subtracted money from the participant who in return could subtract money from the ostensible opponent. Participants subjectively indicated anger and self-estimated treatment affiliation (testosterone or PL administration. A trial-by-trial analysis demonstrated that provocation and success during the repeated games had a stronger influence on participants’ choice to reduce money from the opponent if they had received testosterone. Participants who believed to be in the testosterone group were angrier after the experiment and increased monetary reductions during the task course. In line with theories about mechanisms of testosterone in humans, provocation is shown to be necessary for the agency of exogenous testosterone. Thus, testosterone reinforces the conditional adjustment of aggressive behavior but not aggressive behavior per se. In contrast undirected frustration is not increased by testosterone but probably interferes with cognitive appraisals about biological mechanisms of testosterone.

  5. Exogenous Testosterone Enhances the Reactivity to Social Provocation in Males.

    Science.gov (United States)

    Wagels, Lisa; Votinov, Mikhail; Kellermann, Thilo; Eisert, Albrecht; Beyer, Cordian; Habel, Ute

    2018-01-01

    Testosterone affects human social behavior in various ways. While testosterone effects are generally associated with muscular strength and aggressiveness, human studies also point towards enhanced status-seeking motives after testosterone administration. The current study tested the causal influence of exogenous testosterone on male behavior during a competitive provocation paradigm. In this double blind, randomized, placebo (PL)-controlled study, 103 males were assigned to a PL or testosterone group receiving a colorless PL or testosterone gel. To induce provocation, males played a rigged reaction time game against an ostensible opponent. When participants lost, the opponent subtracted money from the participant who in return could subtract money from the ostensible opponent. Participants subjectively indicated anger and self-estimated treatment affiliation (testosterone or PL administration). A trial-by-trial analysis demonstrated that provocation and success during the repeated games had a stronger influence on participants' choice to reduce money from the opponent if they had received testosterone. Participants who believed to be in the testosterone group were angrier after the experiment and increased monetary reductions during the task course. In line with theories about mechanisms of testosterone in humans, provocation is shown to be necessary for the agency of exogenous testosterone. Thus, testosterone reinforces the conditional adjustment of aggressive behavior but not aggressive behavior per se . In contrast undirected frustration is not increased by testosterone but probably interferes with cognitive appraisals about biological mechanisms of testosterone.

  6. The interactions of multisensory integration with endogenous and exogenous attention.

    Science.gov (United States)

    Tang, Xiaoyu; Wu, Jinglong; Shen, Yong

    2016-02-01

    Stimuli from multiple sensory organs can be integrated into a coherent representation through multiple phases of multisensory processing; this phenomenon is called multisensory integration. Multisensory integration can interact with attention. Here, we propose a framework in which attention modulates multisensory processing in both endogenous (goal-driven) and exogenous (stimulus-driven) ways. Moreover, multisensory integration exerts not only bottom-up but also top-down control over attention. Specifically, we propose the following: (1) endogenous attentional selectivity acts on multiple levels of multisensory processing to determine the extent to which simultaneous stimuli from different modalities can be integrated; (2) integrated multisensory events exert top-down control on attentional capture via multisensory search templates that are stored in the brain; (3) integrated multisensory events can capture attention efficiently, even in quite complex circumstances, due to their increased salience compared to unimodal events and can thus improve search accuracy; and (4) within a multisensory object, endogenous attention can spread from one modality to another in an exogenous manner. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Exogenous CO2 in South American sparkling wine

    Directory of Open Access Journals (Sweden)

    Leonardelli Susiane

    2016-01-01

    Full Text Available The sparkling wine production and consumption have increased significantly in the last years. With the increased demand appear the necessity to check the sparkling wine authenticity, because the practice of adding CO2 in sparkling wine is not allow. A way to control the carbonation process is through the determination of CO2 δ13C, because the sugar added during the second fermentation define the CO2 isotopic value, according to elaboration process. For this reason, the aim of this study was to evaluate the relationship between values of δ13C from still wines and sparkling wines, in order to set up limit values to exogenous carbonation control. Thirty-eight still wines elaborated by microvinification and 59 samples of commercial sparkling wines were analyzed, using an isotope ratio mass spectrometer (IRMS. The most negative value of natural δ13C from still wine found was − 24.7‰, it can be to estimate that lowest values are an indicative of industrial CO2 addition. Among the commercial sparkling wine from South America evaluated in this study, 10% from the samples showed signs of carbonation. Through this research was possible to establish limits of isotopic values to determine the presence of exogenous CO2.

  8. Photoacoustic imaging at 1064nm wavelength with exogenous contrast agents

    Science.gov (United States)

    Upputuri, Paul Kumar; Jiang, Yuyan; Pu, Kanyi; Pramanik, Manojit

    2018-02-01

    Photoacoustic (PA) imaging is a promising imaging modality for both preclinical research and clinical practices. Laser wavelengths in the first near infrared window (NIR-I, 650-950 nm) have been widely used for photoacoustic imaging. As compared with NIR-I window, scattering of photons by biological tissues is largely reduced in the second NIR (NIR-II) window, leading to enhanced imaging fidelity. However, the lack of biocompatible NIR-II absorbing exogenous agents prevented the use of this window for in vivo imaging. In recent years, few studies have been reported on photoacoustic imaging in NIR-II window using exogenous contrast agents. In this work, we discuss the recent work on PA imaging using 1064 nm wavelength, the fundamental of Nd:YAG laser, as an excitation wavelength. The PA imaging at 1064 nm is advantageous because of the low and homogeneous signal from tissue background, enabling high contrast in PA imaging when NIR-II absorbing contrast agents are employed.

  9. Dynamic Financial Constraints: Distinguishing Mechanism Design from Exogenously Incomplete Regimes.

    Science.gov (United States)

    Karaivanov, Alexander; Townsend, Robert M

    2014-05-01

    We formulate and solve a range of dynamic models of constrained credit/insurance that allow for moral hazard and limited commitment. We compare them to full insurance and exogenously incomplete financial regimes (autarky, saving only, borrowing and lending in a single asset). We develop computational methods based on mechanism design, linear programming, and maximum likelihood to estimate, compare, and statistically test these alternative dynamic models with financial/information constraints. Our methods can use both cross-sectional and panel data and allow for measurement error and unobserved heterogeneity. We estimate the models using data on Thai households running small businesses from two separate samples. We find that in the rural sample, the exogenously incomplete saving only and borrowing regimes provide the best fit using data on consumption, business assets, investment, and income. Family and other networks help consumption smoothing there, as in a moral hazard constrained regime. In contrast, in urban areas, we find mechanism design financial/information regimes that are decidedly less constrained, with the moral hazard model fitting best combined business and consumption data. We perform numerous robustness checks in both the Thai data and in Monte Carlo simulations and compare our maximum likelihood criterion with results from other metrics and data not used in the estimation. A prototypical counterfactual policy evaluation exercise using the estimation results is also featured.

  10. Endogenous and Exogenous Natural Adjuvants for Vaccine Development.

    Science.gov (United States)

    Bolhassani, Azam; Talebi, Somayeh; Anvar, Ali

    2017-01-01

    Objective & Background: Various adjuvants are usually co-injected with an antigen for stimulation of effective immune responses. Adjuvants are able to elicit innate immune responses at the injection site. Depending on the activated type of innate responses, adjuvants can modify the quality and quantity of adaptive immune responses. Their mechanisms of action in vaccine development include: a) enhancement of the total antibody titers; b) reduction of the antigen dose; c) induction of potent cell-mediated immunity; d) increase in the speed and duration of the protective response; e) stimulation of mucosal immunity; and f) cross-protection. Up to now, different exogenous adjuvants have been identified to boost immune responses including inorganic compounds, mineral oil, bacterial products, non-bacterial organics, detergents or Quil A, plant saponins, Freund's complete or incomplete adjuvants, and delivery systems. However, some immune responses can be generated in the absence of the exogenous adjuvants. Indeed, endogenous adjuvants released from the cells were known as the danger signals and immunogenic compounds. Several main endogenous adjuvants contain cytokines, chemokines, alarmins, dendritic cells (DCs), toll like receptor (TLR) ligands or agonists, and antibodies. In this review, the immune activities of the natural adjuvants especially endogenous adjuvants and their mechanisms of action are discussed. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  11. Effect of exogenous cellulase enzyme on feed digestibility in lamb

    International Nuclear Information System (INIS)

    Boonek, Lerchat; Shinkoi, Henrry S; Piadang, Nattayana

    2006-09-01

    The aim of this study was to determine the effect of exogenous enzyme on digestibility and N retention in lamb. Eight lambs were randomly allocated to 2 experiment group in group comparison design trial. Experimental treatments were: 1) CTL (No enzyme) and 2 50NZ (Mixed enzyme with high cellulase at 50g/100kg.feed). The digestibility study showed that Exogenous enzyme increased (P<0.05) dry matter and crude protein digestibility of treated lamb compared to those of control. A similar trend (P=0.11) was observed for the NDF digestibility. Mean values for dry matter digestibility were 57.86 and 69.83% and for protein digestibility were 64.76 and 73.38%, for CTL and 50NZ, respectively). The N intake was similar among treatment, averaging 22.57g/head/day. Percent N retained of 50 NZ treated lambs was higher (P<.05) than those of CTL group (mean value were 47.74 and 59.07 for CTC and 50NZ, respectively). Feed efficiency or feed conversion ratio was numerically improved for enzyme-treated groups. Overall, the results of this study provide evidence that mixed cellulase enzyme can be used to improver performance of lambs as compare to non-enzyme diet.

  12. Graphitic carbon nitride nanosheets doped graphene oxide for electrochemical simultaneous determination of ascorbic acid, dopamine and uric acid

    International Nuclear Information System (INIS)

    Zhang, Hanqiang; Huang, Qitong; Huang, Yihong; Li, Feiming; Zhang, Wuxiang; Wei, Chan; Chen, Jianhua; Dai, Pingwang; Huang, Lizhang; Huang, Zhouyi; Kang, Lianping; Hu, Shirong; Hao, Aiyou

    2014-01-01

    Graphical abstract: Schematic drawing of electrochemical oxidize AA, DA and UA on graphitic carbon nitride nanosheets-graphene oxide composite modified electrode. - Highlights: • Synthesize g-C 3 N 4 , GO and CNNS-GO composite. • CNNS-GO composite was the first time for simultaneous determination of AA, DA and UA. • CNNS-GO/GCE displays fantastic selectivity and sensitivity for AA, DA and UA. • CNNS-GO/GCE was applied to detect real sample with satisfactory results. - Abstract: Graphitic carbon nitride nanosheets with a graphite-like structure have strong covalent bonds between carbon and nitride atoms, and nitrogen atoms in the carbon architecture can accelerate the electron transfer and enhance electrical properties effectually. The graphitic carbon nitride nanosheets-graphene oxide composite was synthesized. And the electrochemical performance of the composite was investigated by cyclic voltammetry and differential pulse voltammetry ulteriorly. Due to the synergistic effects of layer-by-layer structures by π-π stacking or charge-transfer interactions, graphitic carbon nitride nanosheets-graphene oxide composite can improved conductivity, electro-catalytic and selective oxidation performance. The proposed graphitic carbon nitride nanosheets-graphene oxide composite modified electrode was employed for simultaneous determination of ascorbic acid, dopamine and uric acid in their mixture solution, it exhibited distinguished sensitivity, wide linear range and low detection limit. Moreover, the modified electrode was applied to detect urine and dopamine injection sample, and then the samples were spiked with certain concentration of three substances with satisfactory recovery results

  13. Simultaneous quantification of endogenous and exogenous plasma glucose by isotope dilution LC-MS/MS with indirect MRM of the derivative tag.

    Science.gov (United States)

    Yu, Lingling; Wen, Chao; Li, Xing; Fang, Shiqi; Yang, Lichuan; Wang, Tony; Hu, Kaifeng

    2018-03-01

    Quantification of endogenous and exogenous plasma glucose can help more comprehensively evaluate the glucose metabolic status. A ratio-based approach using isotope dilution liquid chromatography tandem mass spectrometry (ID LC-MS/MS) with indirect multiple reaction monitoring (MRM) of the derivative tag was developed to simultaneously quantify endo-/exogenous plasma glucose. Using diluted D-[ 13 C 6 ] glucose as tracer of exogenous glucose, 12 C 6 / 13 C 6 glucoses were first derivatized and then data were acquired in MRM mode. The metabolism of exogenous glucose can be tracked and the concentration ratio of endo/exo-genous glucose can be measured by calculating the endo-/exo-genous glucose concentrations from peak area ratio of specific daughter ions. Joint application of selective derivatization and MRM analysis not only improves the sensitivity but also minimizes the interference from the background of plasma, which warrants the accuracy and reproducibility. Good agreement between the theoretical and calculated concentration ratios was obtained with a linear correlation coefficient (R) of 0.9969 in the range of D-glucose from 0.5 to 20.0 mM, which covers the healthy and diabetic physiological scenarios. Satisfactory reproducibility was obtained by evaluation of the intra- and inter-day precisions with relative standard deviations (RSDs) less than 5.16%, and relative recoveries of 85.96 to 95.92% were obtained at low, medium, and high concentration, respectively. The method was successfully applied to simultaneous determination of the endo-/exogenous glucose concentration in plasma of non-diabetic and type II diabetic cynomolgus monkeys. Graphical Abstract The scheme of the proposed ratio-based approach using isotope dilution LC-MS/MS with indirect MRM of the derivative tag for simultaneous quantification of endogenous and exogenous plasma glucose.

  14. Exogenous DNA internalisation by sperm cells is improved by combining lipofection and restriction enzyme mediated integration.

    Science.gov (United States)

    Churchil, R R; Gupta, J; Singh, A; Sharma, D

    2011-06-01

    1. Three types of exogenous DNA inserts, i.e. complete linearised pVIVO2-GFP/LacZ vector (9620 bp), the LacZ gene (5317 bp) and the GFP gene (2152 bp) were used to transfect chicken spermatozoa through simple incubation of sperm cells with insert. 2. PCR assay, Dot Blot hybridisation and Southern hybridisation showed the successful internalisation of exogenous DNA by chicken sperm cells. 3. Lipofection and Restriction Enzyme Mediated Integration (REMI) were used to improve the rate of internalisation of exogenous DNA by sperm cells. 4. Results from dot blot as well as Southern hybridisation were semi-quantified and improved exogenous DNA uptake by sperm cells through lipofection and REMI. Stronger signals were observed from hybridisation of LacZ as well as GFP specific probe with the DNA from lipofected exogenous DNA transfected sperm DNA in comparison with those transfected with nude exogenous DNA.

  15. Hemin offers neuroprotection through inducing exogenous neuroglobin in focal cerebral hypoxic-ischemia in rats

    Science.gov (United States)

    Song, Xue; Xu, Rui; Xie, Fei; Zhu, Haiyuan; Zhu, Ji; Wang, Xin

    2014-01-01

    Objective: To investigate the inducible effect of hemin on exogenous neuroglobin (Ngb) in focal cerebral hypoxic-ischemia in rats. Methods: 125 healthy SD rats were randomly divided into five groups: sham-operation control group, operation group, hemin treatment group, exogenous Ngb treatment group, and hemin and exogenous Ngb joint treatment group. Twenty-four hours after focal cerebral hypoxic-ischemia, Ngb expression was evaluated by immunocytochemistry, RT-PCR, and western blot analyses, while the brain water content and infarct volume were examined. Results: Immunocytochemistry, RT-PCR, and western blot analyses showed more pronounced Ngb expression in the hemin and exogenous Ngb joint operation group than in the hemin or exogenous Ngb individual treatment groups, thus producing significant differences in brain water content and infarct volume (p exogenous Ngb. PMID:24966924

  16. Exogenous Hydrogen Peroxide Contributes to Heme Oxygenase-1 Delaying Programmed Cell Death in Isolated Aleurone Layers of Rice Subjected to Drought Stress in a cGMP-Dependent Manner.

    Science.gov (United States)

    Wang, Guanghui; Xiao, Yu; Deng, Xiaojiang; Zhang, Heting; Li, Tingge; Chen, Huiping

    2018-01-01

    Hydrogen peroxide (H 2 O 2 ) is a reactive oxygen species (ROS) that plays a dual role in plant cells. Here, we discovered that drought (20% polyethylene glycol-6000, PEG)-triggered decreases of HO-1 transcript expression and HO activity. However, exogenous H 2 O 2 contributed toward the increase in HO-1 gene expression and activity of the enzyme under drought stress. Meanwhile, the HO-1 inducer hematin could mimic the effects of the H 2 O 2 scavengers ascorbic acid (AsA) and dimethylthiourea (DMTU) and the H 2 O 2 synthesis inhibitor diphenyleneiodonium (DPI) for scavenging or diminishing drought-induced endogenous H 2 O 2 . Conversely, the zinc protoporphyrin IX (ZnPPIX), an HO-1-specific inhibitor, reversed the effects of hematin. We further analyzed the endogenous H 2 O 2 levels and HO-1 transcript expression levels of aleurone layers treated with AsA, DMTU, and DPI in the presence of exogenous H 2 O 2 under drought stress, respectively. The results showed that in aleurone layers subjected to drought stress, when the endogenous H 2 O 2 level was inhibited, the effect of exogenous H 2 O 2 on the induction of HO-1 was enhanced. Furthermore, exogenous H 2 O 2 -activated HO-1 effectively enhanced amylase activity. Application of 8-bromoguanosine 3',5'-cyclic guanosine monophosphate (8-Br-cGMP) (the membrane permeable cGMP analog) promoted the effect of exogenous H 2 O 2 -delayed PCD of aleurone layers in response to drought stress. More importantly, HO-1 delayed the programmed cell death (PCD) of aleurone layers by cooperating with nitric oxide (NO), and the delayed effect of NO on PCD was achieved via mediation by cGMP under drought stress. In short, in rice aleurone layers, exogenous H 2 O 2 (as a signaling molecule) triggered HO-1 and delayed PCD via cGMP which possibly induced amylase activity under drought stress. In contrast, as a toxic by-product of cellular metabolism, the drought-generated H 2 O 2 promoted cell death.

  17. Exogenous Hydrogen Peroxide Contributes to Heme Oxygenase-1 Delaying Programmed Cell Death in Isolated Aleurone Layers of Rice Subjected to Drought Stress in a cGMP-Dependent Manner

    Science.gov (United States)

    Wang, Guanghui; Xiao, Yu; Deng, Xiaojiang; Zhang, Heting; Li, Tingge; Chen, Huiping

    2018-01-01

    Hydrogen peroxide (H2O2) is a reactive oxygen species (ROS) that plays a dual role in plant cells. Here, we discovered that drought (20% polyethylene glycol-6000, PEG)-triggered decreases of HO-1 transcript expression and HO activity. However, exogenous H2O2 contributed toward the increase in HO-1 gene expression and activity of the enzyme under drought stress. Meanwhile, the HO-1 inducer hematin could mimic the effects of the H2O2 scavengers ascorbic acid (AsA) and dimethylthiourea (DMTU) and the H2O2 synthesis inhibitor diphenyleneiodonium (DPI) for scavenging or diminishing drought-induced endogenous H2O2. Conversely, the zinc protoporphyrin IX (ZnPPIX), an HO-1-specific inhibitor, reversed the effects of hematin. We further analyzed the endogenous H2O2 levels and HO-1 transcript expression levels of aleurone layers treated with AsA, DMTU, and DPI in the presence of exogenous H2O2 under drought stress, respectively. The results showed that in aleurone layers subjected to drought stress, when the endogenous H2O2 level was inhibited, the effect of exogenous H2O2 on the induction of HO-1 was enhanced. Furthermore, exogenous H2O2-activated HO-1 effectively enhanced amylase activity. Application of 8-bromoguanosine 3′,5′-cyclic guanosine monophosphate (8-Br-cGMP) (the membrane permeable cGMP analog) promoted the effect of exogenous H2O2-delayed PCD of aleurone layers in response to drought stress. More importantly, HO-1 delayed the programmed cell death (PCD) of aleurone layers by cooperating with nitric oxide (NO), and the delayed effect of NO on PCD was achieved via mediation by cGMP under drought stress. In short, in rice aleurone layers, exogenous H2O2 (as a signaling molecule) triggered HO-1 and delayed PCD via cGMP which possibly induced amylase activity under drought stress. In contrast, as a toxic by-product of cellular metabolism, the drought-generated H2O2 promoted cell death. PMID:29449858

  18. Study of radio-protective effects of ascorbic acid in rates

    International Nuclear Information System (INIS)

    Bakir, A.M.; Mohammad, A.

    2011-06-01

    The aim of this study was to evaluate the potential radio-protective effects of different ascorbic acid concentrations (vitamin C) in rats before whole body irradiation with total dose of 7 Gy ( 60 Co source) using two different dose rates of 1 and 0.55 Gy.min -1 by increasing percent of surviving. In the first group (1 Gy/m); rats were administered four different concentrations of ascorbic acid (7.5, 12.5, 100, 200 mg/kg b wt ) in drinking water for 30 days before irradiation starting from the ablactation which considered as day 0. Whereas, in the second group (0.55 Gy/m); rats were administered six different concentrations of ascorbic acid (1, 5, 7.5, 12.5, 100, 200 mg/kg b wt) before irradiation with total dose 7 Gy ( 60 Co source). The results have showed that the ascorbic acid enhance the 30-day survival of irradiated rats in 1 and 0.55 Gy/m groups, compared to the control group. The mean cumulated probability of survival of rats (1 Gy/m group) was 66%± 6 (Mean± S.E), 69%± 5, 52%± 9 and 51%± 9 in groups of rats which administered 7.5, 12.5, 100, 200 mg/kg, respectively, versus 41%± 9 in control group for 14 days. While, it was 90%± 2, 90%± 2, 88%± 2, 94%± 1, 84%± 3 and 78%± 3 in groups of rats which administered 1, 5, 7.5, 12.5, 100, 200 mg/kg respectively, versus 52%± 6 in control group for 30 days. Our data, also, indicated that all ascorbic acid concentrations in both groups had significant reduction in mortality and increasing percent of surviving compared to the control groups. We conclude that all ascorbic acid concentrations which used in both groups (1 and 0.55 Gy/m), had radioprotective effects in rats when administrated before irradiations, and this role was more effective against lower dose rate of radiation exposure. (author)

  19. Applied superconductivity

    CERN Document Server

    Newhouse, Vernon L

    1975-01-01

    Applied Superconductivity, Volume II, is part of a two-volume series on applied superconductivity. The first volume dealt with electronic applications and radiation detection, and contains a chapter on liquid helium refrigeration. The present volume discusses magnets, electromechanical applications, accelerators, and microwave and rf devices. The book opens with a chapter on high-field superconducting magnets, covering applications and magnet design. Subsequent chapters discuss superconductive machinery such as superconductive bearings and motors; rf superconducting devices; and future prospec

  20. Distribution of exogenous DNA in upland cotton by pollen tube pathway

    International Nuclear Information System (INIS)

    Yang Shuhua; Ge Cailin; Zhu Jing; Wang Zegang; Luo Shishi; Ni Wanchao

    2007-01-01

    The distribution of exogenous DNA in upland cotton by pollen tube pathway was studied. The results showed that the exogenous DNA could be transported into ovules by dripping and injection. The optimum time for treatment is at 33 h after pollination. The radioactivity in ovules by dripping exogenous DNA was lower than that by injecting. In autoradiogram, the number of sliver grains in the treated ovules was more than that in the controls. (authors)

  1. Exogenous vs. endogenous governance in innovation communities: Effects on motivation, conflict and justice - An experimental investigation

    OpenAIRE

    Störmer, Niclas; Herstatt, Cornelius

    2014-01-01

    In this study we examine the effects of exogenous vs. endogenous governance rules on a virtual community handling an innovative task. Specifically we investigate the relationship between the two modes (exogenous vs. endogenous) and factors such as motivation, conflict and justice. We conducted an experiment with 70 students, divided into teams of five. We manipulated procedural legitimacy by allowing one group to choose a set of rules and giving the other group the same rules exogenously. Our...

  2. Exogenous lipoid pneumonia after ingestion of shark liver oil: a case report

    International Nuclear Information System (INIS)

    Yang, Jae Bum; Seong, Hyeon Lim; Park, Chan Sup; Park, Yang Hee; Lee, Sang Sun

    1991-01-01

    Exogenous lipoid pneumonia was first described in 1925 by Laughlen and a sizeable literature developed, reaching a peak in the 1940s. Two cases of exogenous lipoid pneumonia in children were reported domestically. We wish to report a case of exogenous lipoid pneumonia presented with bilateral air-space consolidation in a 53-year-old man who had a long history of ingestion of shark liver oil. This report describes its radiological findings, along with a review of the literature

  3. Simultaneous detection of ascorbic acid, dopamine, uric acid and tryptophan with Azure A-interlinked multi-walled carbon nanotube/gold nanoparticles composite modified electrode

    Directory of Open Access Journals (Sweden)

    Hayati Filik

    2016-05-01

    Full Text Available In this paper, multi-walled carbon nanotube/Azure A/gold nanoparticle composites (Nafion/AuNPs/AzA/MWCNTs were prepared by binding gold nanoparticles to the surfaces of Azure A-coated carbon nanotubes. Nafion/AuNPs/AzA/MWCNTs based electrochemical sensor was fabricated for the simultaneous determination of ascorbic acid, dopamine, uric acid, and tryptophan. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the electrochemical properties of the modified electrodes. The modified electrode showed excellent electrocatalytic activity toward ascorbic acid, dopamine, uric acid, and tryptophan (pH 7.0. The experiment results showed that the linear response range for simultaneous detection of AA, DA, UA and Trp were 300–10,000 μM, 0.5–50 μM, 0.5–50 μM and 1.0–100 μM, respectively, and the detection limits were 16 μM, 0.014 μM, 0.028 μM and 0.56 μM (S/N = 3. The proposed method offers promise for simple, rapid, selective and cost-effective analysis of small biomolecules. The procedure was also applied to the determination of tryptophan in spiked milk samples.

  4. Exogenous subclinical hyperthyroidism: effect on the cardiovascular system.

    Science.gov (United States)

    Federico Moreno, Karol; Paoli de Valeri, Mariela; Odreman, Rodolfo; Núñez, Tulio; Arata-Bellabarba, Gabriela

    2008-06-01

    To evaluate the effects of exogenous subclinical hyperthyroidism on left ventricular structure and function. Twenty-three patients of both sexes, aged 27 to 70 years, with a diagnosis of exogenous subclinical hyperthyroidism (serum thyroid-stimulating hormone [TSH] ≤ 0.4mU/ml and normal free thyroxine [FT4]) were evaluated. The patients had been taking levothyroxine in suppressive doses for an average of 6.7 years (1 to 35 years). Twenty euthyroid individuals matched for age, sex and body mass index were selected as controls. A medical history was obtained and symptoms of thyrotoxicosis were quantified in all subjects. To evaluate left ventricular structure and function, as well as atrial conduction time, a two-dimensional echocardiogram and pulsed echo and tissue echo Doppler with electrocardiography monitoring were performed. The index of hemodynamic compensation of the left ventricular mass was calculated. Hyperthyroid symptom scores were significantly higher in patients than in controls (p=0.0001). A positive correlation was found between hyperthyroidism scores and FT4 (p=0.005) and ejection fraction (p=0.04) and a negative correlation was found with TSH levels (p=0.03). End-diastolic volume, stroke volume, cardiac output and stroke work were significantly higher in patients with SH (p=0.04, p=0.02, p=0.05 and p=0.01, respectively). A positive correlation was found between fractional shortening and FT4 level (p=0.022) and levothyroxine dose (p=0.016) and between stroke work and FT4 level (p=0.034). Left ventricular mass, diastolic function and atrial conduction time were similar in patients and controls. Our study suggests that patients with exogenous subclinical hyperthyroidism have hemodynamic changes resulting from adaptation to the biological effects of levothyroxine on the cardiovascular system. However, structural changes are not produced. Copyright © 2008 Sociedad Española de Endocrinología y Nutrición. Published by Elsevier Espana. All rights

  5. Altitude Acclimatization and Blood Volume: Effects of Exogenous Erythrocyte Volume Expansion

    National Research Council Canada - National Science Library

    Sawka, M

    1996-01-01

    ...: (a) altitude acclimatization effects on erythrocyte volume and plasma volume; (b) if exogenous erythrocyte volume expansion alters subsequent erythrocyte volume and plasma volume adaptations; (c...

  6. Solubilities of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid in water

    Energy Technology Data Exchange (ETDEWEB)

    Mishelevich, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel); Apelblat, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel)], E-mail: apelblat@bgu.ac.il

    2008-05-15

    The solubility in water of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid was determined in the 278.15 K to 343.15 K temperature range. The solubility of these compounds served to permit the evaluation of the apparent molar enthalpies of solution.

  7. Solubilities of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid in water

    International Nuclear Information System (INIS)

    Mishelevich, Alexander; Apelblat, Alexander

    2008-01-01

    The solubility in water of magnesium-L-ascorbate, calcium-L-ascorbate, magnesium-L-glutamate, magnesium-D-gluconate, calcium-D-gluconate, calcium-D-heptagluconate, L-aspartic acid, and 3-nitrobenzoic acid was determined in the 278.15 K to 343.15 K temperature range. The solubility of these compounds served to permit the evaluation of the apparent molar enthalpies of solution

  8. Nitrate uptake and utilization is modulated by exogenous gamma-aminobutyric acid in Arabidopsis thaliana seedlings.

    Science.gov (United States)

    Barbosa, Jose M; Singh, Narendra K; Cherry, Joe H; Locy, Robert D

    2010-06-01

    Exogenously applied GABA modulates root growth by inhibition of root elongation when seedlings were grown in vitro on full-strength Murashige and Skoog (MS) salts, but root elongation was stimulated when seedlings were grown on 1/8 strength MS salts. When the concentration of single ions in MS salts was individually varied, the control of growth between inhibition and stimulation was found to be related to the level of nitrate (NO(3)(-)) in the growth medium. At NO(3)(-) concentrations below 40 mM (full-strength MS salts level), root growth was stimulated by the addition of GABA to the growth medium; whereas at concentrations above 40 mM NO(3)(-), the addition of GABA to the growth medium inhibited root elongation. GABA promoted NO(3)(-) uptake at low NO(3)(-), while GABA inhibited NO(3)(-) uptake at high NO(3)(-). Activities of several enzymes involved in nitrogen and carbon metabolism including nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase (NADH-GOGAT), NADP-dependent isocitrate dehydrogenase (NADP-ICDH), and phosphoenol pyruvate carboxylase (PEPCase) were regulated by GABA in the growth medium. Supplementing 1/8 strength MS medium with 50 mM GABA enhanced the activities of all of the above enzymes except ICDH activities in root tissues. However, at full-strength MS, GABA showed no inhibitory effect on the activities of these enzymes, except on GS in both root and shoot tissues, and PEPCase activity in shoot tissues. Exogenous GABA increased the amount of NR protein rather than its activation status in the tissues. This study shows that GABA affects the growth of Arabidopsis, possibly by acting as a signaling molecule, modulating the activity of enzymes involved in primary nitrogen metabolism and nitrate uptake.

  9. Rewards modulate saccade latency but not exogenous spatial attention.

    Directory of Open Access Journals (Sweden)

    Stephen eDunne

    2015-07-01

    Full Text Available The eye movement system is sensitive to reward. However, whilst the eye movement system is extremely flexible, the extent to which changes to oculomotor behaviour induced by reward paradigms persist beyond the training period or transfer to other oculomotor tasks is unclear. To address these issues we examined the effects of presenting feedback that represented small monetary rewards to spatial locations on the latency of saccadic eye movements, the time-course of learning and extinction of the effects of rewarding saccades on exogenous spatial attention and oculomotor IOR. Reward feedback produced a relative facilitation of saccadic latency in a stimulus driven saccade task which persisted for 3 blocks of extinction trials. However this hemifield-specific effect failed to transfer to peripheral cueing tasks. We conclude that rewarding specific spatial locations is unlikely to induce long-term, systemic changes to the human oculomotor or attention systems.

  10. CT and HR-CT of exogenous allergic alveolitis

    International Nuclear Information System (INIS)

    Lederer, A.; Kullnig, P.; Pongratz, M.

    1992-01-01

    The CT changes on conventional and high resolution CT in 14 patients with exogeneous allergic alveolitis (EAA) were analysed retrospectively. There were 8 patients with clinically subacute disease, 5 patients in a chronic stage and 1 patient with acute EAA. The appearances and their distribution were examined. Seven of the 8 patients in the subacute stage showed a ground glass pattern and multiple nodules of less than 2 mm. All patients in the chronic stage showed a combination of fine infiltrates, small nodules and irregular linear densities; distortion of the pulmonary pattern was present in 3 cases. The patient with acute EAA showed diffuse dense areas of consolidation in both lungs as well as multiple nodules and a ground glass pattern. The CT appearances of EAA correspond with the basic micropathology and, within the clinical context, permit diagnostic classification. (orig.) [de

  11. Rewards modulate saccade latency but not exogenous spatial attention.

    Science.gov (United States)

    Dunne, Stephen; Ellison, Amanda; Smith, Daniel T

    2015-01-01

    The eye movement system is sensitive to reward. However, whilst the eye movement system is extremely flexible, the extent to which changes to oculomotor behavior induced by reward paradigms persist beyond the training period or transfer to other oculomotor tasks is unclear. To address these issues we examined the effects of presenting feedback that represented small monetary rewards to spatial locations on the latency of saccadic eye movements, the time-course of learning and extinction of the effects of rewarding saccades on exogenous spatial attention and oculomotor inhibition of return. Reward feedback produced a relative facilitation of saccadic latency in a stimulus driven saccade task which persisted for three blocks of extinction trials. However, this hemifield-specific effect failed to transfer to peripheral cueing tasks. We conclude that rewarding specific spatial locations is unlikely to induce long-term, systemic changes to the human oculomotor or attention systems.

  12. Avoidable cancers in the Nordic countries. Exogenous hormones

    DEFF Research Database (Denmark)

    Winther, J F; Dreyer, L; Tryggvadottir, L

    1997-01-01

    of the breast and uterine cervix) and beneficial effects (protection against cancers of the ovary and endometrium), indicate that 95 cases of breast cancer and 40 of cervical cancer will be caused by oral contraceptives annually around 2000 in the Nordic countries, which corresponds to 0.6% of all breast......The well-described influence of several aspects of reproductive life on the risk for cancer in the reproductive organs has raised concern regarding the safety of exogenous hormones, particularly since sex hormones have become one of the most widely used drugs among women in the western world...... aged 15-45 years in 1985 ranging between 6% (Norway) and 19% (Sweden) and proportions of current users in 1994 ranging between 20% (Norway) and 28% (Sweden). Such data on the current and long-term use of oral contraceptives by the female populations, linked with relative estimates of adverse (cancers...

  13. On the possibility of cyclic postvariscan exogene ore formation

    International Nuclear Information System (INIS)

    Schmid, H.

    1980-01-01

    The appearance of time-bound or time-related ore deposits is well known. As for the variscan-orogen-area, the author tries to explain the formation of time-related deposits of U-Cu in the Permian, Pb, Zn(Ba,Sr) in Muschelkalk and lower Keuper, Mn in Lias and Fe in Dogger by a systematic sequence of terrigene solutions from variscan weathering-detritus according to following scheme: Firstly, in the Permian, the mobile elements U and Cu were leached. In Muschelkalk and Keuper climatic (weathering) conditions caused decomposition of silicates (particularly potassium-feldspars), so that Pb, Ba, Sr and Zn became free. Then in special acid leaching conditions, Mn and Fe could be transported. This system allows to suppose exogene origin for some deposits for which in literature endogene-sedimentary formation is considered. (orig.) [de

  14. Atherosclerosis in familial lines of pigeons fed exogenous cholesterol.

    Science.gov (United States)

    Patton, N M; Brown, R V; Middleton, C C

    1975-01-01

    Exogenous cholesterol was fed to F1 pigeons of high and low serum cholesterol differentiated lines of White Carneau and Racing Homer pigeons that had previously been developed by selection and positive assortive mating. The serum cholesterol response of the various high and low lines was dependent upon the breed and the amount of cholesterol in the diet. Racing Homer pigeons were found to be more resistant to aortic atherosclerosis and more susceptible to coronary atherosclerosis than White Carneau pigeons. Data from necropsy examinations showed significant differences in both aortic and coronary atherosclerosis between lines within the White Carneau breed, but no differences between lines of the Racing Homer breed. Mean organ weights for the 4 lines of pigeons were reported.

  15. Transient expression of exogenous gus gene in Porphyra yezoensis (Rhodophyta)

    Science.gov (United States)

    Kuang, Mei; Wang, Su-Juan; Li, Yao; Shen, Da-Leng; Zeng, Cheng-Kui

    1998-03-01

    Electroporation, PEC, PEG plus electroporation and Biolistics methods were tested in gene transformation of P. yezoensis. The exogenous gus was from plasmid of pBI121 and pCAMBIA1301, both contain the CaMV35S promoter. The receptors included the protoplasts, tissues and free-living conchocelis filaments of P. yezoensis. Several factors, for example, the voltage, capacitance and bivalent cations, etc., were studied. Results show that these four methods are all efficient for gene transformation in P. yezoensis; and that PEG is the best one, with transformation efficiency of up to 4×10-5. GUS activity was detected 26 days after transformation by using PEG method.

  16. A sensitive competitive binding assay for exogenous and endogenous heparins

    International Nuclear Information System (INIS)

    Dawes, J.; Pepper, D.S.

    1982-01-01

    A new type of assay for heparins has been devised, in which the test material competes with 125 I-labelled heparin for binding to protamine-Sepharose. The assay is very sensitive and will measure heparin concentrations down to 10 ng ml-1. It responds to both the degree of sulphation and the molecular weight of acidic polysaccharides, but is independent of their biological activities. It can be used to quantitate heparins in biological fluids after pretreatment of the samples with protease. In this way endogenous heparins were measured in normal human serum, plasma and urine. The assay is extremely versatile and has great potential for the investigation of endogenous and exogenous heparins

  17. Exogenous endothelial cells as accelerators of hematopoietic reconstitution

    Directory of Open Access Journals (Sweden)

    Mizer J

    2012-11-01

    Full Text Available Abstract Despite the successes of recombinant hematopoietic-stimulatory factors at accelerating bone marrow reconstitution and shortening the neutropenic period post-transplantation, significant challenges remain such as cost, inability to reconstitute thrombocytic lineages, and lack of efficacy in conditions such as aplastic anemia. A possible means of accelerating hematopoietic reconstitution would be administration of cells capable of secreting hematopoietic growth factors. Advantages of this approach would include: a ability to regulate secretion of cytokines based on biological need; b long term, localized production of growth factors, alleviating need for systemic administration of factors that possess unintended adverse effects; and c potential to actively repair the hematopoietic stem cell niche. Here we overview the field of hematopoietic growth factors, discuss previous experiences with mesenchymal stem cells (MSC in accelerating hematopoiesis, and conclude by putting forth the rationale of utilizing exogenous endothelial cells as a novel cellular therapy for acceleration of hematopoietic recovery.

  18. A TAD further: exogenous control of gene activation.

    Science.gov (United States)

    Mapp, Anna K; Ansari, Aseem Z

    2007-01-23

    Designer molecules that can be used to impose exogenous control on gene transcription, artificial transcription factors (ATFs), are highly desirable as mechanistic probes of gene regulation, as potential therapeutic agents, and as components of cell-based devices. Recently, several advances have been made in the design of ATFs that activate gene transcription (activator ATFs), including reports of small-molecule-based systems and ATFs that exhibit potent activity. However, the many open mechanistic questions about transcriptional activators, in particular, the structure and function of the transcriptional activation domain (TAD), have hindered rapid development of synthetic ATFs. A compelling need thus exists for chemical tools and insights toward a more detailed portrait of the dynamic process of gene activation.

  19. Does oculomotor readiness mediate exogenous capture of visual attention?

    Science.gov (United States)

    MacLean, Gregory H; Klein, Raymond M; Hilchey, Matthew D

    2015-10-01

    The oculomotor readiness hypothesis makes 2 predictions: Shifts in covert attention are accompanied by preparedness to move one's eyes to the attended region, and preparedness to move one's eyes to a region in space is accompanied by a shift in covert attention to the prepared location. Both predictions have been disconfirmed using an endogenous attention task. In the 2 experiments presented here, the same 2 predictions were tested using an exogenous attention task. It was found that participants experienced covert capture without accompanying oculomotor activation and experienced oculomotor activation without accompanying covert capture. While under everyday conditions the overt and covert orienting systems may be strongly linked, apparently they can nonetheless operate with a high degree of independence from one another. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

  20. Dog rose (Rosa canina L.) as a functional ingredient in porcine frankfurters without added sodium ascorbate and sodium nitrite.

    Science.gov (United States)

    Vossen, Els; Utrera, Mariana; De Smet, Stefaan; Morcuende, David; Estévez, Mario

    2012-12-01

    The effect of dog rose (Rosa canina L.; RC), rich in polyphenols and ascorbic acid, on lipid and protein oxidation, colour stability and texture of frankfurters was investigated. Four treatments were prepared: with 5 or 30 g/kg RC extract and without sodium ascorbate and sodium nitrite (5RC and 30RC, respectively), a positive control (with sodium ascorbate and sodium nitrite; PC) and a negative control (without sodium ascorbate, sodium nitrite or RC extract; NC). Hexanal values were much higher throughout storage in NC compared to RC and PC frankfurters (Prose can act as a natural antioxidant in frankfurters, but not as full replacer for sodium nitrite. Copyright © 2012 Elsevier Ltd. All rights reserved.