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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Vliv zinkových nanokomplexů na zdravotní stav organismu modelových zvířat

Jeník, David January 2019 (has links)
Zinc is widely used as an alternative to antibiotic in piglets. Recent studies demonstrated the antibacterial effect of zinc nanoparticles. It is believed that zinc nanoparticles will exhibit better antibiotic effects than previously used medication zinc. There is a need to define ZnNPs effect on the organism. This thesis compares the influence of administration of zinc oxide nanoparticles and zinc standard forms at the dose of 2000 mg/Zn/kg diet in rat organism. The antioxidant status of rats and toxicity of zinc and zinc nanoparticles were monitored. The level of accumulated zinc for blood was on average 12 mg / kg ± 6 mg / kg, for liver 74 mg / kg ± 50 mg / kg, for kidneys 37 mg / kg ± 30 mg / kg for both nanoparticles and normal zinc . ZnNPs and zinc oxide did not extremely influence antioxidant status of samples of blood, liver and kidney. A significant effect was observed with GSH levels. Histological study of liver and duodenum showed slight tissue damage after administration of both zinc and nanoparticles. Zinc nanoparticles demonstrated beneficial effects as well as standard form.
52

Does Melatonin Have Therapeutic Use in Tinnitus?

Merrick, Leah, Youssef, Dima, Tanner, Michelle, Peiris, Alan N. 01 January 2014 (has links)
Melatonin, a hormone produced by the pineal gland, may be a promising treatment option for tinnitus. The primary functions of this hormone are believed to be the initiation and maintenance of sleep because its secretions coincide with circadian rhythms. Some investigators have noted that melatonin may alleviate subjective symptoms of tinnitus. Moreover, melatonin may have properties protective against ototoxic drugs such as amikacin, gentamicin, or cancer therapeutic agents that are dose dependent. In vitro, melatonin has demonstrated antioxidative properties and it has been postulated that these antioxidative properties contribute to the alleviation of tinnitus. Melatonin levels used to obtain these findings in vitro, however, are at supraphysiologic levels; therefore, it is more likely that the benefits from taking supplemental melatonin occur from minimal antioxidative properties, sleep enhancement, or other potential methods of action that are not yet understood. Melatonin offers minimal risk of toxicity with modest daily doses such as 1 to 3 mg, aswell as a low cost and favorable adverse effect profile for older adults. In addition to potential benefits in the treatment of tinnitus, melatonin also may have beneficial neurogenerative properties. We recommend that melatonin be considered for use in patients with significant tinnitus.
53

Methionine: an essential amino acid and potential enhancer of antioxidant systems in swine diets

Humphrey, Rebecca M 25 November 2020 (has links)
L-Methionine (L-Met) is a new product that supplies the biologically active form of methionine. Therefore, the objective of this study was to elucidate the benefits of dietary L-Met supplementation relative to the industry standard DL-Met. Sixteen gilts with an initial BW 81.2±7.93 kg were individually penned and randomly allotted to one of two equivalent dietary treatments for 37 days in 2 trials (8 pigs/trial): DL-Met (0.050% of diet) or L-Met (0.052% of diet). Body weight and feed intake were measured on days 0, 19, and 37 to calculate performance measures. Pigs were harvested and carcasses assessed on day 38. Liver, loin muscle, and subcutaneous fat were collected for antioxidant assessments. Data were analyzed via Proc Mixed in SAS and significance was set at P ≤ 0.05. There were no differences between dietary treatments in growth performance, carcass characteristics, or antioxidant status (P > 0.05). In conclusion, methionine form did not differentially impact animal growth or antioxidant status.
54

Antioxidant Effects of Apples and Apple Products in Diet

Zhao, Shi 28 July 2011 (has links)
No description available.
55

Antioxidant studies of fullerene and metallofullerene derivatives and fluorescence studies of terbium-containing metallofullerene derivatives

Huang, Rong 10 February 2022 (has links)
Fullerenes and metallofullerenes have been discovered to have a lot of applications in the biomedical area, for instance, they have been shown to have antioxidant, anti-virus, anti-cancer, immunological properties, etc. However, the hydrophobicity nature of fullerenes and metallofullerenes raises the need for functionalized hydrophilic fullerenes and metallofullerenes. Also, the advancement of the purification techniques of fullerenes and metallofullerenes makes the isolation of new fullerenes and metallofullerenes possible. Therefore, discovering the biomedical applications of these newly found fullerenes and metallofullerenes is also of vital importance. In Chapter 1, we provided a comprehensive background on the history of fullerenes and metallofullerenes, synthesis and purification methods of fullerenes and metallofullerenes, and some of their biological applications, including antioxidant applications and fluorescence applications. Some important fullerene and metallofullerenes and milestones in this area were also discussed. In Chapter 2, we demonstrated the antioxidant and anti-inflammation ability of a conjugate, FIFIFK(Cy5)PEG24K(NH2)CONH2-C60, that consisted of a peptide that binds specifically to a formyl peptide receptor-1 (FPR-1), which expresses on activated macrophages, and a carboxyl-group-functionalized C60, which is the first discovered and most used fullerene is history. We showed that the fullerene-peptide conjugate had great ability as a radical scavenger and to reduce the volume of inflammatory tissue. In Chapter 3, we demonstrated the antioxidant and anti-inflammation ability of several metallofullerene derivatives, including amino-Gd3N@C80, amino-Sc3N@C80, carboxy-Gd3N@C80, and carboxyl-Sc3N@C80. Amino-group-functionalized metallofullerenes were found to have higher radical scavenging ability and anti-inflammation ability. In Chapter 4, we developed fluorescent metallofullerene derivatives, including Tb3N@C80(NH2)9(OH)4NO2 and Tb3N@C80(CH2CH2COOH)21(OH)18. The fluorescence properties of the derivatives of fullerenes or metallofullerenes were normally realized by the addition of fluorescent moieties on the carbon cage of fullerenes or metallofullerenes. However, the fluorescence of our newly developed metallofullerene derivative was realized by the tri-terbium nitride cluster inside the carbon cage. This saved the multi-step synthesis of the fluorescence probe and maintained the simplicity of the structure of the metallofullerene derivative. These derivatives of terbium-containing metallofullerene also showed radical scavenging ability towards hydroxyl radicals. In Chapter 5, we developed another fluorescent Tb3N@C80 derivative, Tb3N@C80[DiPEG2000]. The advantage of this fluorescent metallofullerene derivative was that it was easier to purify compared to small-functional-groups-functionalized Tb3N@C80 derivatives. This newly developed fluorescent Tb3N@C80 derivative also showed great fluorescent ability and radical scavenging ability. In Chapter 6, we provided a summary of the studies on the antioxidant and fluorescent properties of fullerenes and metallofullerenes' derivatives that were discussed in this dissertation. / Doctor of Philosophy / Fullerenes and metallofullerenes' have large carbonaceous outer structures that give them possibilities for a lot of chemical reactions. The conjugated carbonaceous outer structures also endow them with exceptional antioxidant ability by reacting with the oxidant species. Therefore, fullerenes and metallofullerenes can be considered as great antioxidants, which are substances that can prevent or slow damage to cells caused by oxidants, in most cases free radicals or other unstable oxidant molecules that the body produces as reactions to environmental and other pressures. Fullerenes and metallofullerenes are sometimes called "free-radical scavengers". However, fullerenes and metallofullerenes are not soluble in biological systems, therefore, it's necessary to attach functional groups onto the outer cage-like structures of fullerenes and metallofullerenes to make them water-soluble, while maintaining their great antioxidant properties. Fullerenes and metallofullerenes are not limited to antioxidant applications, and with the attachment of specialized moieties, for instance, short peptides, they can be made of additional applications. Different metals in these metallofullerenes also provide them with specialized applications. Herein, we have developed a series of water-soluble fullerenes and metallofullerenes and compared their antioxidant properties. We have also developed a water-soluble C60-peptide conjugate that can specifically bind to inflammatory cells and ease the inflammatory condition. We also synthesized a series of metallofullerene derivatives that had dual modalities fluorescent properties and antioxidant properties.
56

Glucose metabolism in human spermatozoa

Williams, Andrew C. January 2000 (has links)
No description available.
57

Synthetic approaches to alkaloid natural products using the Stille coupling

Mee, Simon P. H. January 2003 (has links)
No description available.
58

Pharmacologically active flavonoids from the anticancer, antioxidant and antimicrobial extracts of Cassia angustifolia Vahl

Ahmed, Shabina Ishtiaq, Hayat, Muhammad Qasim, Tahir, Muhammad, Mansoor, Qaisar, Ismail, Muhammad, Keck, Kristen, Bates, Robert B. 11 November 2016 (has links)
Background: Cassia angustifolia Vahl. (commonly known as senna makkai or cassia senna), native to Saudi Arabia, Egypt, Yemen and also extensively cultivated in Pakistan, is a medicinal herb used traditionally to cure number of diseases like liver diseases, constipation, typhoid, cholera etc. This study was conducted to evaluate the in-vitro antimicrobial, antioxidant and anticancer assays and phytochemical constituents of aqueous and organic extracts of C. angustifolia leaves. Methods: The antimicrobial activities of C. angustifolia aqueous and organic (methanol, ethanol, acetone, ethyl acetate) extracts were investigated by the disk diffusion method. These extracts were further evaluated for antioxidant potential by the DPPH radical scavenging assay. Anticancer activities of the extracts were determined by the MTT colorimetric assay. The total phenolic and flavonoid contents of C. angustifolia extracts were evaluated by the Folin-Ciocalteu method and aluminum chloride colorimetric assay, respectively. The structures of the bioactive compounds were elucidated by NMR and ESI-MS spectrometry. Results: Bioactivity-guided screening of C. angustifolia extracts, led to the isolation and identification of three flavonoids quercimeritrin (1), scutellarein (2), and rutin (3) reported for the first time from this plant, showed significant anticancer activity against MCF-7 (IC50, 4.0 mu g/mu L), HeLa (IC50, 5.45 mu g/mu L), Hep2 (IC50, 7.28 mu g/mu L) and low cytotoxicity against HCEC (IC50, 21.09 mu g/mu L). Significant antioxidant activity was observed with IC50 2.41 mu g/mL against DPPH radical. Moreover, C. angustifolia extracts have the potential to inhibit microbial growth of E. cloacae, P. aeruginosa, S. mercescens and S. typhi. Conclusion: C. angustifolia extracts revealed the presence of quercimeritrin (1), scutellarein (2), and rutin (3), all known to have useful bioactivities including antimicrobial, antioxidant and anticancer activities.
59

Antioxidační vlastnosti extraktů z květů Sambucus nigra. / Antioxidant properties of Sambucus nigra flower extracts.

Štěpánová, Zuzana January 2013 (has links)
1. Abstract Purpose of this thesis was to prove and determine antioxidant activity of flower extracts from black elder (Sambucus nigra L.) and compile summary of their content substances and effects. Sambuci flos is often used in natural therapy and food industry. The main content substances are flavonoids, phenolic acids, triterpenoids, further are contained in flowers sterols, mucilage, essential oils, tannins. Flavonoids are the most significant, specifically rutin and kvercetin, because they can show antioxidant, antiviral, anti-inflammatory and anticancer properties. Flowers are used mainly for their diuretic, diaforetic, expectorant, analgetic effects. Method DPPH (2,2-difenyl-1- pikrylhydrazyl) was used for determination antioxidant activity of methanolic flower extracts. Results of antioxidant activity were expressed as IC50 values (concentration of extract which causes 50% reduction of radical). The average observed IC50values were 0,79 mg/ml and 0,83 mg/ml. The individual IC50values have changed fluently during development of flowers, they range from 1,086 mg/ml and 0,701 mg/ml in both collections. Deviations can be caused by ongoing synthesis of the secondary metabolites.
60

Modulation of root antioxidant status to delay cassava post-harvest physiological deterioration

Page, Michael January 2009 (has links)
Cassava ranks seventh in terms of worldwide crop production, providing a staple for over half a billion people. The production of cassava is limited by several factors, with post-harvest physiological deterioration (PPD) of storage roots a major constraint. PPD is a process initiated on harvesting and mediated by reactive oxygen species (ROS) that ultimately renders storage roots unpalatable and unmarketable. It is similar to a conventional plant wound response, but crucially lacks efficient wound repair and down-regulation of stress signalling. Therefore, the strategy utilised here to modulate PPD focussed on increasing the ROS scavenging ability of storage root tissue through a biotechnological approach. Three expression plasmids were produced, harbouring cassava genes encoding the antioxidant enzymes APX, CAT and SOD under the control of the storage rootspecific StPAT promoter. In addition, a reporter expression plasmid was created, with StPAT driving the expression of GusP. Transgenic Arabidopsis plants containing the StPAT::GusP cassette demonstrated root-specific GusP staining. Non-root tissue also showed wound-inducible GusP activity conferred by the StPAT promoter. This novel activity was detected almost immediately after wounding and occurred independently of ethylene, MeJa and ROS. The 3’ 261 bp of the StPAT promoter was sufficient to confer wound-inducible expression and contained putative wound responsive cis regulatory motifs. Analysis of PATATIN function indicated a role during early responses to wounding in the liberation of free fatty acids from cell membranes. Over-expression of the target genes in the model plant Arabidopsis increased the antioxidant enzyme activity in the roots of selected lines. Transgenic plants generally exhibited similar levels of oxidative stress resistance to wild-type plants, a result due in part to the efficient nature of the oxidative stress response of Arabidopsis – the APX activity of wild-type plants increased to transgenic levels under H2O2 stress. However, PPD in cassava is at least partially the result of a poor antioxidant response to harvesting, and so transformation of cassava with the expression plasmids remained a viable strategy. Transgenic cassava plants harbouring the expression cassettes are being generated and will soon be assessed for PPD resistance.

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