Academic literature on the topic 'GPX'

The possible renal and hepatic toxicities of ethylenediaminetetraacetic acid (EDTA) in bean cooking media were studied using 100 male albino mice. Two sublethal doses of EDTA were used to explore their toxic effects; 20 mg/kg and 200 mg/kg, which corresponded to 1/100th and 1/10th of LD50, respectively. Accordingly, the toxicity study was performed using 50 mice, divided into five groups ( n = 10/group) as follows: group 1 (Gp1) served as a negative control and was orally administered normal saline; group 2 (Gp2) was administered the bean cooking medium; group 3 (Gp3) was administered EDTA (200 mg/kg); group 4 (Gp4) was administered bean cooking medium containing 20 mg/kg of EDTA; and group 5 (Gp5) was administered bean cooking medium containing 200 mg/kg of EDTA. The results showed no significant changes in liver and kidney functions in Gp2 while Gp3, Gp4, and Gp5 exhibited significant increases in adverse liver and kidney function markers. Hematocrit values were significantly decreased in Gp3 and Gp5, while the total white blood cells counts were significantly decreased in Gp3 and significantly increased in Gp5. The number of platelets was decreased in Gp3, Gp4, and Gp5. The blood levels of sodium (Na+), iron (Fe2+), and calcium (Ca2+) were decreased in Gp3, Gp4, and Gp5 due to the chelating effects of EDTA. The hepatic and renal architectures were disorganized in Gp3, Gp4, and Gp5 with some hemorrhagic manifestations in livers and kidneys of mice. These results demonstrate that EDTA in bean cooking is harmful in mice under the conditions of this study, and the potentially harmful effects in humans supports restricting its use.

The experiment was conducted to evaluate kindey selenium status, glutathione peroxidase (GPx) activity and GPx-1 expression in mice fed with nanoselenium. Sixty KM mice, female and male in half, were randomly divided into control, sodium selenite and nanoselenium groups. 0.5 milliliter of water, sodium selenite (2 μg Se/mL) and nanoselenium (2 μg Se/mL) were respectively supplemented to the three groups in oral (ig) every day. Whole experiment lasted for 28 days. Kindey selenium contents, GPx activities and GPx-1 mRNA expression were analyzed at experiment trrmination. The results showed that kindey selenium contents and GPx activities in nanoselenium group and sodium selenite group were very significantly higher than those in control group (P<0.01); kindey GPx activities in nanoselenium group were significantly higher than that in sodium selenite group (P<0.05). Kindey mRNA expression of GPx-1 was approx 166% higher in nanoselenium group and approx 157% higher in sodium selenite group than that in control group. Kindey mRNA expression of GPx-1 was approx 3.50 % higher in nanoselenium group than that in sodium selenite group. The results indicated that nanoselenium supplementation could significantly enhance kindey selenium contents, GPx activities and GPx-1 mRNA expression in mice, nanoselenium was more available than sodium selenite in increasing kindey selenium contents, GPx activities and GPx-1 mRNA expression in mice.

Abstract We have used a cloned cDNA for the major human selenoprotein, glutathione peroxidase (GPx), to assess the mode of regulation of human GPx gene (GPX-1) expression by selenium. When the HL-60 human myeloid cell line is grown in a selenium-deficient medium, GPx enzymatic activity decreases 30-fold compared with selenium-replete cells. Upon return to a medium containing selenium in the form of selenite, GPx activity in the cells starts to increase within 48 hours and reaches maximal (selenium-replete) levels at 7 days. Steady-state immunoreactive protein levels correlate with enzymatic activity. Cycloheximide inhibits the rise in GPx activity that accompanies selenium replenishment, indicating that protein synthesis is required for the increase. However, GPx mRNA levels and the rate of transcription of the human GPx gene change very little and thus appear to be independent of the selenium supply. Thus the human GPx gene appears to be regulated post-transcriptionally, probably cotranslationally, in response to selenium availability.

We have used a cloned cDNA for the major human selenoprotein, glutathione peroxidase (GPx), to assess the mode of regulation of human GPx gene (GPX-1) expression by selenium. When the HL-60 human myeloid cell line is grown in a selenium-deficient medium, GPx enzymatic activity decreases 30-fold compared with selenium-replete cells. Upon return to a medium containing selenium in the form of selenite, GPx activity in the cells starts to increase within 48 hours and reaches maximal (selenium-replete) levels at 7 days. Steady-state immunoreactive protein levels correlate with enzymatic activity. Cycloheximide inhibits the rise in GPx activity that accompanies selenium replenishment, indicating that protein synthesis is required for the increase. However, GPx mRNA levels and the rate of transcription of the human GPx gene change very little and thus appear to be independent of the selenium supply. Thus the human GPx gene appears to be regulated post-transcriptionally, probably cotranslationally, in response to selenium availability.

GPX-PDE (glycerophosphodiester phosphodiesterase; EC 3.1.4.46) is a relatively poorly characterized enzyme that catalyses the hydrolysis of various glycerophosphodiesters (glycerophosphocholine, glycerophosphoethanolamine, glycerophosphoglycerol, glycerophosphoserine and bis-glycerophosphoglycerol), releasing sn-glycerol 3-phosphate and the corresponding alcohol. In a previous study, we demonstrated the existence of a novel GPX-PDE in the cell walls and vacuoles of plant cells. Since no GPX-PDE had been identified in any plant organism, the purification of GPX-PDE from carrot cell walls was attempted. After extraction of cell wall proteins from carrot cell suspension cultures with CaCl2, GPX-PDE was purified up to 2700-fold using, successively, ammonium sulphate precipitation, gel filtration and concanavalin A–Sepharose. Internal sequence analysis of a 55 kDa protein identified in the extract following 2700-fold purification revealed strong similarity to the primary sequence of GLPQ, a bacterial GPX-PDE. To confirm the identity of plant GPX-PDE, an Arabidopsis thaliana cDNA similar to that encoding the bacterial GPX-PDE was cloned and overexpressed in a bacterial expression system, and was used to raise antibodies against the putative Arabidopsis thaliana GPX-PDE. Immunochemical assays performed on carrot cell wall proteins extracted by CaCl2 treatment showed a strong correlation between GPX-PDE activity and detection of the 55 kDa protein, validating the identity of the plant GPX-PDE. Finally, various properties of the purified enzyme were investigated. GPX-PDE is a multimeric enzyme, specific for glycerophosphodiesters, exhibiting a Km of 36 µM for glycerophosphocholine and active within a wide pH range (from 4 to 10). Since these properties are similar to those of GLPQ, the bacterial GPX-PDE, the similarities between plant and bacterial enzymes are also discussed.

Cellular glutathione peroxidase (GPx-1) is the most abundant intracellular isoform of the GPx antioxidant enzyme family. In this study, we hypothesized that GPx-1 deficiency directly induces an increase in vascular oxidant stress, with resulting endothelial dysfunction. We studied vascular function in a murine model of homozygous deficiency of GPx-1 (GPx-1−/−). Mesenteric arterioles of GPx-1−/− mice demonstrated paradoxical vasoconstriction to β-methacholine and bradykinin, whereas wild-type (WT) mice showed dose-dependent vasodilation in response to both agonists. One week of treatment of GPx-1−/− mice withl-2-oxothiazolidine-4-carboxylic acid (OTC), which increases intracellular thiol pools, resulted in restoration of normal vascular reactivity in the mesenteric bed of GPx-1−/−mice. We observed an increase of the isoprostane iPF2α-III, a marker of oxidant stress, in the plasma and aortas of GPx-1−/− mice compared with WT mice, which returned toward normal after OTC treatment. Aortic sections from GPx-1−/− mice showed increased binding of an anti-3-nitrotyrosine antibody in the absence of frank vascular lesions. These findings demonstrate that homozygous deficiency of GPx-1 leads to impaired endothelium-dependent vasodilator function presumably due to a decrease in bioavailable nitric oxide and to increased vascular oxidant stress. These vascular abnormalities can be attenuated by increasing bioavailable intracellular thiol pools.

The persistence of antibodies to glycoprotein X (gpX) in the serum of pigs experimentally infected with pseudorabies virus (PRV) was determined using an anti-gpX enzyme-linked immunosorbent assay (ELISA). Antibodies to gpX were detected for at least 365 days postchallenge in nonvaccinated pigs. Previous sensitization of pigs by vaccination with S/PRV had no apparent effect on the antibody response of pigs to gpX postchallenge. In determining previous exposure of pigs to PRV strains containing the gpX gene, the anti-gpX ELISA was highly specific, but its sensitivity was lower than the standard serological procedures currently used for detecting PRV antibodies.

Glutathione peroxidase-1 (GPx-1) is a crucial antioxidant enzyme, the deficiency of which promotes atherogenesis. Accordingly, we examined the mechanisms by which GPx-1 deficiency enhances endothelial cell activation and inflammation. In human microvascular endothelial cells, we found that GPx-1 deficiency augments intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression by redox-dependent mechanisms that involve NFκB. Suppression of GPx-1 enhanced TNF-α-induced ROS production and ICAM-1 expression, whereas overexpression of GPx-1 attenuated these TNF-α-mediated responses. GPx-1 deficiency prolonged TNF-α-induced IκBα degradation and activation of ERK1/2 and JNK. JNK or NFκB inhibition attenuated TNF-α induction of ICAM-1 and VCAM-1 expression in GPx-1-deficient and control cells, whereas ERK1/2 inhibition attenuated only VCAM-1 expression. To analyze further signaling pathways involved in GPx-1-mediated protection from TNF-α-induced ROS, we performed microarray analysis of human microvascular endothelial cells treated with TNF-α in the presence and absence of GPx-1. Among the genes whose expression changed significantly, dual specificity phosphatase 4 (DUSP4), encoding an antagonist of MAPK signaling, was down-regulated by GPx-1 suppression. Targeted DUSP4 knockdown enhanced TNF-α-mediated ERK1/2 pathway activation and resulted in increased adhesion molecule expression, indicating that GPx-1 deficiency may augment TNF-α-mediated events, in part, by regulating DUSP4.

The differential pseudorabies virus (PRV) vaccines currently in use in the USA have deletions of the genes coding for the glycoprotein I (gl) and/or glycoprotein X (gpX). The absence of gI and/or gpX allow for the serologic differentiation of vaccinated swine from PRV-infected swine using differential enzyme-linked immunosorbent assays (ELISAs). A newly developed pseudorabies vaccine virus has 4 deletions of the viral genome: the genes coding for gI, gpX, and thymidine kinase and a portion of the repeat region to attenuate the virus. The purpose of this work was to evaluate the diagnostic compatibility of the gI/gpX gene-deleted vaccine with 3 differential vaccines and 3 differential ELISAs currently in use. Pigs vaccinated 3 times with the gI/gpX gene-deleted vaccine remained seronegative on the 3 differential ELISAs tested. Pigs previously vaccinated with either a gI or gpX gene-deleted vaccine and then vaccinated with the gI/gpX gene-deleted vaccine remained seronegative on the respective gI or gpX differential assay.

The aim of this work is to study and theoretically process existing movement options of station in OPNET Modeler environment. These options are described in first part. Furthermore to design and implement function to display path obtained from real-world conditions and done to station following this route during simulation. Coordinates used to move station are obtained by GPX format, which is used to store clearly the GPS coordinates. Second part is devoted to describing creation of this function, first using PHP script, then direct implementation into OPNET Modeler environment using C++.

Cells are continuously facing an oxidative challenge induced by free radicals. These may be generated in different way, i. e. by electron escaping the mitochondrial transport chain, activity of the NADPH oxidase and nitric oxide synthase family of enzymes and autoxidation of favoenzymes. However, the radicals superoxide (*O2- ) and nitric oxide (NO*) do not appear so destructive when produced in tissues. The abundance of superoxide dismutases (SODs) assures that O2*- is immediately dismutated to O2 and the apparently less dangerous H2O2. In pathologic conditions, however, H2O2 is used to produce hypoclorous acid (HOCl) and similarly reactive compounds by the heme peroxidases of leukocytes, or the hydroxyl radical (OH*) by Fenton-like chemistry. Similarly, under these conditions, peroxynitrite (ONOO-) -the reaction product between NO* and *O2- - is transformed into more toxic species. Interestingly, no enzyme has so far been discovered that could detoxify OH*, RO*, singlet oxygen, or HOCl. Evidently, nature was sage enough not to embark in this effort, due to the difficulty to compete with the diffusion-limited reaction of these species on biological targets. However living cells are continuously facing an oxidative challenge and self-protection appears mandatory. This is essentially achieved by preventing radical formation from hydroperoxides (R-OOH) and ONOO-. Interestingly, this appears particularly relevant on the light of the observation that these species may act as mediators of diverse physiological responses such as cell proliferation, differentiation and migration. The enzymes involved in mammals to handle R-OOH and ONOO-, belong to two distinct protein families, the glutathione peroxidases (GPxs) and the peroxiredoxins (Prxs). Both act on H2O2 and on ONOO- -although ONOO- is generally believed to be a better substrate for Prx than GPxs- and, also, on a wide spectrum of alkyl hydroperoxides comprising the products of lipoxygenases. GPxs are widely distributed in nature, from bacteria to humans. They use either selenium or sulfur in the redox center that is oxidized by the hydroperoxide, thus forming an oxidized enzyme intermediate, which is regenerated in its reduced form by a reductant. This is not always glutathione (GSH), as the name of the family should suggest. The redox center is remarkably conserved in the whole family and it is made of a catalytic tetrad containing Sec or Cys, Gln, Trp and Asn. When it contains selenium, as it typically occurs in mammalian GPx -the ‘SecGPxs’- the oxidized intermediate formed upon reaction of the catalytic moiety with the R-OOH -believed to be a selenol (SeO-)- is reduced by GSH. In this reaction a selenodisulfide intermediate is formed, that is displaced by a second GSH, yielding GSSG and reduced enzyme. When it contains sulphur, instead, as in the GPxs of non-vertebrates and plants (CysGPxs), the reducing substrate is a Trx or a ‘redoxin’ of the Trx family, and an intrachain disulphide is the oxidized intermediate of the enzyme. This mechanism requires, besides the ‘peroxidatic Cys ‘(CP), a second ‘resolving Cys’ (CR). The sole monomeric SecGPx of vertebrates -GPx4- does not bear the CR residue, is active on GSH and, obviously, does not form the intermediate intrachain selenodisulfide. The ‘canonic mechanism’ of GPxs, involving a CR when the redox center is a CP instead of a ‘peroxidatic Sec’ (UP) and the consequent use of Trx or ‘redoxins’ as the reducing substrate for the intermediate disulphide (CP - CR) has been challenged by the discovery of GPx7 and GPx8 in mammals. These are two monomeric GPxs of the endoplasmic reticulum (ER), containing a CP but missing a Cys residue –located within the aminoacid stretch of the alpha 4 helix of the GPx thioredoxin fold- where the CR residue of non-vertebrate and plants GPxs is found. Here, GPx7 has been characterized as the prototype of these unusual 1CysGPx. Although at low levels, GPx7 is widely distributed in tissues. Both, its NH2-terminal peptide and the C terminal KREDL motif proved to be functional to ER entrance and retention respectively. Kinetic studies on GPx7 have been carried out using phospholipid hydroperoxides, the most appropriate for monomeric GPxs, using the enzyme expressed in E. coli, fused with synuclein to overcome an otherwise very poor expression. From steady state kinetics the rate constant for the oxidation of the active site resulted rather high (k+1=9.5 x E03 M-1sec-1), whilst the rate of the regeneration of the catalyst by GSH remarkably low (k’+2=12.6 M-1sec-1). Unexpectedly, the oxidized active site is instead rapidly reduced by a ‘redoxin’, protein disulfide isomerase (PDI) (k’+2=3.5 x E03 M-1sec-1), but not by Trx. This evidence was corroborated by the affinity constant for PDI measured by SPR (KD= 5.2 µM). Furthermore the presence in GPx7 of a Cys residue replacing the resolving function of the CR of non-vertebrates and plants GPxs, was ruled out by mutagenesis. Thus, the ‘canonical mechanism’ by which in GPx a CR is required for being reduced by a ‘redoxin’ does not apply to GPx7. This enzyme indeed accepts electrons from a ‘redoxin’ such as PDI by a mechanism involving the CP only. GPx7, and the structurally similar GPx8, therefore, represent rare exceptions within the family of glutathione peroxidases, for being 1CysGPx preferentially reduced by a ‘redoxin’. In fact the GPxs family is mostly contributed by the non-vertebrates ‘2CysGPx’ that are functionally Trx peroxidases. Although these data frame the physiological function of GPx7 in the area of oxidative folding of proteins in ER, no evidence was obtained in this respect. Searching for adaptive response to ER stress alternative to the unfolded protein response (UPR), we observed increased phosphorylation of the extracellular signal regulated kinase 1-2 (ERK 1-2) by GPx7 silencing following a proliferative stimulus by the fibroblast growth factor (FGF). These data finalize the enzymatic characterization of GPx7 as a ‘non-canonical’ member of the GPxs family, do not support the role in ER stress but envisage a role in the cross talk between the redox status of ER and growth factor signaling.
Le cellule vanno continuamente incontro a ‘stress ossidativo’ indotto da radicali liberi. Questi possono essere generati in diversi modi, ad esempio da elettroni che sfuggono alla catena respiratoria mitocondriale, dall'attività delle NADPH ossidasi o dalle ossido nitrico sintasi e dalla autossidazione di flavoenzimi. Tuttavia, i radicali superossido (*O2-) e ossido nitrico (NO*) non appaiono così distruttivi per i tessuti. L'abbondanza di superossido dismutasi (SOD) assicura che l’ *O2- sia immediatamente dismutato a O2 e H2O2, una sostanza apparentemente meno pericolosa. Ciò non toglie che, in condizioni patologiche, l’H2O2 possa essere usata per produrre acido ipocloroso (HOCl) e altri composti reattivi dalle eme perossidasi dei leucociti, oppure per produrre il radicale idrossile (OH*) attraverso la reazione di Fenton. Allo stesso modo, in queste condizioni, il perossinitrito (ONOO-), prodotto di reazione tra NO* e *O2-, si trasforma in specie più tossiche. È interessante notare il fatto che non sia stato mai trovato enzima capace di detossificare OH*, RO*, ossigeno singoletto, oppure HOCl. Evidentemente, la natura è stata saggia abbastanza da non impegnarsi in uno sforzo impossibile, per la difficoltà di competere con l’altissima reattività di queste specie su bersagli biologici, limitata solo dalla diffusione. Tuttavia le cellule devono costantemente affrontare ‘stress ossidativo’ e pertanto l’autoprotezione è obbligatoria. Questa è perseguita prevenendo la formazione di radicali dagli idroperossidi (R-OOH) e dal perossinitrito. Ciò è particolarmente rilevante alla luce del fatto che queste sostanze stanno emergendo come mediatori di diverse risposte fisiologiche quali la proliferazione, la differenziazione e la migrazione cellulare. Gli enzimi dei mammiferi implicati nella detossificazione degli R-OOH e ONOO- appartengono a due distinte famiglie di proteine, le glutatione perossidasi (GPxs) e le peroxiredossine (Prx). Entrambi agiscono sull’H2O2 o sul ONOO- - anche se, generalmente il ONOO- è ritenuto substrato migliore per le Prx rispetto alle GPxs – e, inoltre, su un ampio spettro di idroperossidi alchilici comprendenti i prodotti della lipossigenasi. Le GPxs sono ampiamente distribuite in natura, dai batteri all'uomo. Utilizzano sia selenio che zolfo nel centro catalitico ossidoriduttivo, che viene ossidato dall’R-OOH, formando così un intermedio ossidato che viene rigenerato da un agente riducente. Questo non è sempre glutatione (GSH), come il nome di questa famiglia di enzimi potrebbe suggerire. Il centro redox delle GPxs è notevolmente conservato in tutta la famiglia ed è costituito da una tetrade catalitica composta da Sec o Cys, Gln, Trp e Asn. Quando contiene selenio, come tipicamente nelle GPx dei mammiferi – le ‘SecGPxs’-, l’intermedio ossidato, formatosi dalla reazione del centro catalitico con l’R-OOH, probabilmente il selenolo (SeO-), viene ridotto dal GSH, il quale forma un intermedio selenodisulfuro che viene poi ridotto da una seconda molecola di GSH, con produzione di GSSG ed enzima ridotto. Quando invece contiene zolfo, come tipicamente nelle GPxs dei non-vertebrati e nelle piante (CysGPxs), il substrato riducente è una preferenzialmente la tioredossina (Trx) o una ‘redossina’ della famiglia delle Trxs, e l'intermedio ossidato dell’enzima è un disolfuro intracatena. Per questo è necessario, oltre alla ‘Cys perossidasica’ (CP), un secondo residuo di Cys la ‘Cys resolving’ (CR). L'attuale, unica SecGPx monomerica nei vertebrati - la GPx4- non presenta il residuo CR, è ridotta dal GSH e ovviamente non forma un intermedio selenodisulfuro intracatena. Il ‘meccanismo canonico’ delle GPxs, che implica quindi una CR quando il centro redox è una CP invece di una Sec perossidasica (UP) e quindi l’uso di preferenziale di Trx o altre ‘redossine’ come substrato riducente, è stato rimesso in discussione dalla scoperta, nei mammiferi, di due nuove GPx, la GPx7 e la GPx8. Queste sono due GPx monomeriche del reticolo endoplasmatico (ER), contenenti una CP, senza un residuo di Cys nello ‘stretch’ di aminoacidi dove si trova la CR delle altre CysGPx dei non-vertebrati e delle piante. In questa tesi, abbiamo caratterizzato la GPx7, come prototipo di queste insolite ‘1CysGPx’. Anche se a bassi livelli, la GPx7 è ampiamente distribuita nei tessuti. Il peptide segnale presente all’estremità NH2-terminale e il motivo C-terminale KREDL sono funzionali per l’ingresso e la ritenzione nell’ER, rispettivamente. Gli studi cinetici sulla GPx7 sono stati effettuati su idroperossidi fosfolipidi (PL-OOH), il substrato più appropriato per le GPxs monomeriche, utilizzando enzima espresso in E. coli, fuso con sinucleina per ottenere alti livelli di espressione. Dalla cinetica in stato stazionario, la costante cinetica per l'ossidazione del sito attivo è risultata piuttosto elevata (k+1=9.5 x E03 M-1sec-1), mentre costante cinetica per la rigenerazione del catalizzatore con GSH notevolmente bassa (k’+2=12.6 M-1sec-1). Sorprendentemente, il sito attivo ossidato è invece rapidamente ridotto da una ‘redossina’, la protein disulfide isomerase (PDI) (k’+2=3.5 x E03 M-1sec-1) ma non dalla Trx. L’interazione PDI-GPx7 è stata confermata dalla misura della costante di affinità della GPx7 per la PDI mediante SPR (KD= 5.2 µM). Inoltre è stata esclusa, mediante mutagenesi, la eventuale presenza nella GPx7 di un residuo Cys che possa fare la funzione della CR tipica delle GPxs dei non-vertebrati e delle piante. Quindi, il ‘meccanismo canonico’ mediante il quale nelle GPxs è richiesta una CR per essere ridotte da una ‘redossina’ non si applica alla GPx7 (e probabilmente neanche alla GPx8, che è strutturalmente simile). Questo enzima infatti, accetta elettroni da un ‘redossina’ come la PDI attraverso un meccanismo che implica la sola CP. La GPx7 (e la GPx8) si configurano quindi come insolite ‘1CysGPx’ della famiglia delle glutation perossidasi, poiche’ sono di fatto rare eccezioni. Infatti, la famiglia delle glutation perossidasi è per la maggior parte composta da ‘2CysGPx’ dei non-vertebrati e delle piante che sono funzionalmente Trx perossidasi. Sebbene questi dati sembrerebbero inquadrare la funzione fisiologica della GPx7 nel ‘protein folding’ che avviene nell’ER, nessuna evidenza è stata da noi ottenuta in questo senso. In cerca di una risposta adattativa alternativa all’unfolded protein response (UPR), abbiamo osservato un aumento di fosforilazione della extracellular signal regulated kinase 1-2 (ERK 1-2) in seguito al silenziamento della GPx7 dopo uno stimolo proliferativo con il fattore di crescita dei fibroblasti (FGF). Questi dati finalizzano la caratterizzazione enzimatica della GPx7 come un membro ‘non-canonico’ della famiglia delle GPxs, non suggeiscono un ruolo nello stress del ER, ma indicano invece un ruolo nel cross talk tra lo stato redox del ER e segnali provenienti da fattori di crescita.

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The antioxidant action of organic selenium compounds, as well as ebselen and diphenyl diselenide (DPDS), is closely connected to its ability of generating the selenol group. (In) this study it was evaluated the in vitro antioxidant effect of new mono and diselenide compounds, where it was compared whether the formation of p-methyl-selenol from compounds 1-phenyl-3-(p-tolylselanyl)propan-2-amine (C1) and 1,2-dip-tolyldiselenide (C4) and o-methoxy-selenol from compounds 1-(2-methoxyphenylselanyl)-3-phenylpropan-2-amine (C2) and 1,2-bis(2-methoxyphenyl) diselenide (C3) may be involved with their antioxidant effects. The mono and diselenide compounds were tested in their Fe(II) and sodium nitroprusside (SNP)-induced lipid peroxidation in rat brain and liver homogenates and also in their antioxidant ability in phosphomolybdenum test-reductionand and DPPH radical. Besides, the effects of the compounds in the antioxidant enzymes thioredoxin reductase (TrxR) and glutathione peroxidase (GPx) were quantified. The new compounds oxidant effects were investigated through the thiol oxidase assay and the cellular viability of isolated leukocytes. The results demonstrated that the compounds obtained a significant reduce on the lipid peroxidation induced by different pro-oxidants, as well as an antioxidant effect similarly when compared to ascorbic acid equivalents. In the same manner, the compounds did not present thiol oxidase activity. Furthermore, they did not preset any decrease on the cellular viability of leucocytes. The compounds C1 and C2 did not show mimetic activity of GPx enzyme or had a substrate effect on TrxR enzyme, probably due the amino group presence on their chemical structures which must have inhibited the selenol formation. However, DPDS analog-compounds presented a mimetic activity of GPx, as well as they showed an increase in the TrxR activity, presumably due the formation of the selenol groups (p-methyl-selenol and o-methoxy-selenol).
A ação antioxidante dos compostos orgânicos de selênio, como o ebselen e o disseleneto de difenila (DPDS), está intimamente envolvida com a capacidade de formação do grupamento selenol. Neste estudo foi avaliado o perfil antioxidante in vitro de novos compostos mono e disseleneto, onde foi comparado se a formação do p-metil-selenol pelos compostos 1-fenil-3-(p-tolilselenil)propano-2-amina (C1) e o 1,2-dip-tolildisseleneto (C4), assim como a formação do grupamento o-metoxi-selenol pelos compostos 1-(2-metoxifenilselenil)-3-fenilpropano-2-amina (C2) e 1,2-bis(2-metoxifenil)disseleneto (C3) pode estar associados com os efeitos antioxidantes apresentados. Os novos compostos mono e disseleneto foram avaliados quanto a capacidade de redução dos níveis de peroxidação lipídica induzida por Fe(II) e nitroprussiato de sódio em homogenatos de cérebro e fígado de ratos, assim como também foi avaliada a capacidade antioxidante através do ensaio da redução do fosfomolibdênio e do radical DPPH. Além disso, foram quantificados os efeitos dos compostos quanto à atividade das enzimas antioxidantes, tioredoxina redutase (TrxR) e glutationa peroxidase (GPx). O efeito oxidante, dos novos compostos, foi investigado através do ensaio da tiol oxidase e da viabilidade celular de leucócitos isolados. Decorrente dos resultados obtidos foi possível evidenciar que ambos os compostos apresentaram uma redução significativa da peroxidação lipídica quando induzidas por diferentes pro oxidantes assim como, uma capacidade antioxidante total semelhante a equivalentes de acido ascórbico. Da mesma forma, os compostos não apresentaram efeito tiol oxidase, assim como não apresentaram uma diminuição da viabilidade celular de leucócitos. Os compostos C1 e C2 não apresentaram atividade mimética a enzima GPx assim como, também não serviram de substrato para a enzima TrxR, provavelmente devido a presença do grupamento amino nas estruturas químicas destas moléculas o que incapacitou a formação dos respectivos grupamentos selenois. No entanto, os compostos análogos ao DPDS apresentaram atividades miméticas a GPx, assim como também apresentaram uma aumento na atividade da TrxR provavelmente devido a formação dos selenois (p-metil-selenol e o-metoxi-selenol).

This master thesis describes development of Photography Geotagging Application from an introduction to the issues, through the analysis and design to the resulting implementation. The reader should be able understand to issues of time in geotagging using the GPS tracks records. He will also understand where and how metadata are stored. The big part of thesis is dedicated to the implementation of application which leads the reader through building the application architecture, the photography representation and loading their metadata with program ExifTool. Gradually will be explained the convertors of coordinates and GPS track parsers, which are used to synchronization. The final application allows the user synchronize photography with GPS track and display them on the map.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
O papel fisiolÃgico das peroxidases de glutationa (GPX) da mitocÃndria em plantas à muito pouco conhecido. Suas relaÃÃes com a fotossÃntese sÃo desconhecidas, ainda mais na presenÃa de estresse salino. Essa enzima possui grande importÃncia na remoÃÃo de H2O2 e hidroperÃxidos orgÃnicos, contribuindo na proteÃÃo oxidativa e na homeostase redox. Neste estudo, mutantes de arroz silenciados nos genes OsGPX1 ou OsGPX3, das proteÃnas mitocondriais, foram utilizados para entender os mecanismos fisiolÃgicos do papel dessa enzima no crescimento e fotossÃntese. Adicionalmente, estes processos foram estudados tambÃm em condiÃÃes de estresse salino para as plantas silenciadas em OsGPX1. Os resultados mostram, pela primeira vez, que a deficiÃncia de uma GPX mitocondrial à capaz de restringir o crescimento vegetal por deficiÃncia na fotossÃntese. Este efeito deve ser causado indiretamente por mudanÃas nas redes genÃticas e metabÃlicas desencadeadas por alteraÃÃes nos nÃveis de H2O2 (aumentado) e/ou glutationa reduzida (diminuÃda). à provÃvel que o estado redox alterado em mitocÃndrias pelo efeito da GPX possa aumentar a fotossÃntese atravÃs da comunicaÃÃo entre esta organela e cloroplastos por mecanismos ainda nÃo estabelecidos. AlÃm disso, o gene OsGPX1 mostrou ter papel significativo no controle do movimento estomÃtico, que à crucial para a eficiÃncia do uso da Ãgua sob condiÃÃo de estresse salino. As GPX mitocondriais tambÃm parecem estar envolvidas com a dissipaÃÃo do excesso de energia luminosa na forma de calor (NPQ) no aparato do fotossistema II e na rota da fotorrespiraÃÃo. Em conclusÃo, o gene OsGPX1, associado com seu produto proteico e mudanÃas desencadeadas nas redes metabÃlicas e gÃnicas, sÃo essenciais para o crescimento de arroz pelo aumento da fotossÃntese, especialmente a nÃvel de eficiÃncia de uso da luz envolvendo atividade do fotossistema II e eficiÃncia quÃntica do CO2 em condiÃÃes normais de crescimento. Adicionalmente, a GPX1 aparenta mostrar uma importÃncia menor para a resistÃncia ao estresse salino.
The physiological role of glutathione peroxidases (GPX) in plant mitochondria is little known. Their relations with the photosynthesis are unknown, even more in presence of salt stress. This enzyme have great importance in H2O2 and organic hydroperoxides scavenging, contributing in oxidative protection and redox homeostasis. In this study, silenced rice mutants in OsGPX1 and OsGPX3 genes, coding for the mitochondrial proteins, were used to better understand the physiological mechanisms of the role of this protein in growth and photosynthesis. Additionally, these processes were also studied in salt stress conditions with the plants silenced in OsGPX1. The results show, for the first time, that the lacking of a mitochondrial GPX is capable of restricting plant growth by impairment in photosynthesis. This response might be an indirect consequence of changes in gene and metabolic networks trigged by alterations in H2O2 (raised) and/or reduced glutathione (diminished). It is likely that the altered redox state in mitochondria by GPX effects can improve photosynthesis through cross-talk between this organelle and chloroplasts by yet unknown mechanisms. Furthermore, the OsGPX1 gene showed significant role in stomatal control, which is crucial to the water use efficiency under salt stress conditions. The mitochondrial GPX also seems to be involved with dissipation of excess light energy as heat (NPQ) in photosystem II apparatus and in photorespiratory pathway. In conclusion, the OsGPX1 gene, associated with it protein product and changes in gene and metabolic networks, are essential to rice growth by improvement of photosynthesis, especially at light use efficiency level involving photosystem II activity and CO2 quantum efficiency in normal and growth conditions. Additionally, GPX1 seems to be less important to salt stress tolerance.

Os recém-nascidos possuem o sistema antioxidante imaturo, por haver baixa tensão de oxigênio no ambiente intrauterino durante a vida fetal. Logo após o nascimento, as alterações súbitas das condições fisiológicas e ambientais causam significativo aumento no consumo de oxigênio, desencadeando, assim, a produção de radicais livres. Tais condições promovem vulnerabilidade dos neonatos ao efeito negativo do estresse oxidativo, o que potencialmente podem prejudicar a vitalidade neonatal. O presente estudo teve como objetivo comparar o perfil antioxidante e estresse oxidativo de neonatos e fêmeas caninas no periparto eutócico vaginal ou cesariana eletiva, e avaliar a influência da condição obstétrica para o estado oxidativo. Foram selecionadas 21 cadelas gestantes, as quais, constituíram dois grupos amostrais, de acordo com a condição obstétrica: Eutocia Vaginal (n = 10) e Cesariana Eletiva (n = 11); e seus respectivos neonatos foram alocados em subgrupos de acordo com a condição obstétrica e momento do nascimento: Eutocia Vaginal Inicial (n=10), Eutocia Vaginal Final (n = 9), Cesariana Eletiva Inicial (n = 11) e Cesariana Eletiva final (n= 10). As cadelas foram avaliadas no período pródromo do parto, intraparto; uma hora e três dias pós-parto, quando amostras de sangue foram colhidas para análise do perfil antioxidante [dosagem das enzimas superóxido dismutase (SOD), glutationa peroxidase (GPx), dosagem da concentração de tióis totais e determinação do status antioxidante total(TAC)] e do estresse oxidativo [dosagem da peroxidação lipídica (TBARS) e da oxidação de proteínas]. Os neonatos foram avaliados quanto ao escore Apgar aos 0 e 60 minutos do nascimento; avaliação clínica (frequências cardíaca e respiratória; escore de tônus muscular, irritabilidade reflexa e coloração de mucosa, aferição da temperatura corporal), lactatemia sanguínea, oximetria de pulso, determinação do perfil antioxidante e do estresse oxidativo e aferição do peso corporal aos 0, 60 minutos, às 12, 24 horas e ao 3º dia pós nascimento. As cadelas do Grupo Eutocia Vaginal apresentaram maior peroxidação lipídica, oxidação de proteínas e atividade de SOD e menor atividade de GPx e concentração de tióis totais em comparação ao Grupo Cesariana Eletiva. A capacidade antioxidante total elevou-se após 1h do parto em comparação aos outros momentos de avaliação no Grupo Cesariana Eletiva. Embora os neonatos do Grupo Eutocia Vaginal tenham apresentado melhores parâmetros de vitalidade neonatal, em comparação ao Grupo Cesariana Eletiva, todos os neonatos apresentaram adequada evolução do escore Apgar, coloração de mucosa, irritabilidade reflexa, tônus muscular e oxigenação periférica após 1h do nascimento. A lactatemia sanguínea foi maior no Grupo Eutocia Vaginal, bem como nos neonatos nascidos ao final do parto. A peroxidação lipídica foi superior nos neonatos nascidos por eutocia vaginal em comparação aos nascidos por cesariana eletiva, enquanto a oxidação de proteínas mostrou-se maior nos primeiros neonatos nascidos por eutocia vaginal em comparação aos nascidos ao final do parto. Porém, resultado contrário foi verificado para o Grupo Cesariana Eletiva, pois os neonatos nascidos ao final da cirurgia apresentaram maior valor de oxidação de proteínas. Ademais, para os neonatos nascidos ao final do parto, o Grupo Cesariana Eletiva apresentou maior oxidação proteica em comparação ao Grupo Eutocia Vaginal. A atividade da GPx foi superior nos neonatos nascidos por cesariana eletiva. Em conclusão, a condição obstétrica impõe diferenças no perfil oxidativo e antioxidante em cadelas e neonatos, os quais apresentam estado oxidativo semelhante, denotando influência materna sobre o equilíbrio oxidativo dos recém-nascidos.
Newborns have an immature antioxidant system, due to low oxygen exposure in intrauterine environment during fetal life. Immediately after birth, sudden changes of physiological and environmental conditions cause a significant increase in oxygen consumption, resulting in the production of free radicals. These conditions turn the newborn vulnerable to the negative effects of oxidative stress, which potentially can impair neonatal vitality. This study aimed to compare the antioxidant profile and oxidative stress of neonates and canine females during vaginal labour or elective cesarean section, and to evaluate whether the obstetric condition influences their oxidative status. For this purpose, 21 pregnant bitches were subjected to two experimental groups, according to the obstetric condition: Vaginal Eutocia (n = 10) and Elective Cesarian Section (n = 11) and their respective newborns were allocated into subgroups according to the obstetric condition and moment of birth: Inicial Vaginal Eutocia (n=10), Final Vaginal Eutocia (n = 9), Inicial Elective Cesarian Section (n = 11) and Final Elective Cesarian Section (n= 10). Bitches were evaluated during the preparatory phase of whelping, intrapartum; one and 72 hours postpartum, when blood samples were collected for analysis of the antioxidant profile [Superoxide Dismutase (SOD) and Glutathione Peroxidase (GPx) activity enzymes assays, Total Antioxidant Capacity (TAC) assay and Total Thiols Concentration assay] and oxidative stress [lipid peroxidation (TBARS) and protein oxidation assays]. Neonates were evaluated for the Apgar score at 0 and 60 minutes of birth; clinical evaluation (heart and respiratory rates; muscle tone, irritability reflex and mucous color score; and body temperature), blood lactate, pulse oximetry, determination of antioxidant profile and oxidative stress, and body weight measurement at 0, 60 minutes, 12, 24 and 72 hours after birth. The Vaginal Eutocia bitches had higher lipid peroxidation, protein oxidation and SOD activity and lower GPx activity and total thiols concentration in comparison to the Elective Cesarian Section Group. Total antioxidant capacity was higher 1 hour postpartum compared to the others evaluation moments in the Elective Cesarian Section Group. Although neonates from the Vaginal Eutocia Group presented better neonatal vitality than those from the Elective Cesarian Section, all neonates presented adequate evolution of the Apgar score, mucous color, irritability reflex, muscle tone and pulse oximetry 1 hour postpartum. Blood lactatemia was higher in the Vaginal Eutocia Group, as well as for the last neonates. Lipid peroxidation was higher in neonates born by vaginal eutocia compared to those born by elective cesarean section, whereas protein oxidation was higher in the first neonates born by vaginal eutocia compared to those born at the end of delivery. Conversely, Elective Cesarian Section neonates born at the end of surgery had higher protein oxidation. In addition, for those neonates born at the end of delivery, the Elective Cesarian Section group presented higher protein oxidation compared to the Vaginal Eutocia group. Furthermore, GPx activity was higher in neonates born by elective caesarean section. In conclusion, the obstetric condition imposes differences in the oxidative and antioxidant profile in bitches and neonates with similar oxidative status, denoting maternal influence on the oxidative balance of the newborns.

La contaminazione da micotossine può coinvolgere tutti i comparti della filiera agroalimentare e rappresenta a tutti gli effetti un potenziale di perdita economica. Il settore zootecnico è particolarmente esposto alle ricadute della contaminazione, in termini di costi sanitari per gli effetti cronici sulla salute animale conseguenti all’esposizione alle micotossine. La prevenzione in campo mediata da appropriate tecniche agronomiche rappresenta, per quanto ovvio, la più importante strategia per ridurre la contaminazione dei mangimi. Un approccio completamente differente è quello che si basa sulla possibilità di ridurre gli effetti delle tossine sull’animale, modificando la sua alimentazione attraverso l’integrazione nutrizionale di opportuni agenti chemiopreventivi. Numerose sono le specie chimiche, di origine naturale o sintetica, che hanno dimostrato una efficacia chemiopreventiva del danno ossidativo indotto da micotossine ed emergono per la loro efficacia il selenio e i suoi composti organici ed inorganici. L’azione antineoplastica del selenio è nota da molto tempo e ha trovato conferme in numerosi studi epidemiologici che indicano una relazione inversa tra assunzione di selenio con la dieta e rischio di sviluppo di una patologia neoplastica. Questa tesi di dottorato ha avuto come obiettivo la progettazione, la sintesi e lo studio di composti diamminoacidici contenenti un atomo di calcogeno (selenio o zolfo), mimici dalla glutatione perossidasi (GPx) e auspicabilmente attivi nel contrasto del danno ossidativo indotto dall’aflatossina B1 (AFB1). Le specie diamminoacidiche sintetizzate appartengono alla classe dei Sec-derivati, ovvero sono costitute da un residuo di L-selenocisteina (o L-cisteina) a cui è legato attraverso l’atomo di calcogeno un altro L-amminoacido. Alla porzione calcogenica, che rappresenta il sito redox, sono stati infatti ancorati rispettivamente un residuo di L-prolina modificata e un residuo di L-leucina. Al termine delle fasi di sintesi e caratterizzazione chimico-fisica dei calco-diamminoacidi è stata intrapresa una serie di indagini biochimiche in collaborazione con due distinti laboratori in Germania. I risultati ottenuti hanno permesso di dimostrare che alcuni Sec-derivati sono in grado di ridurre i perossidi attraverso un meccanismo catalitico che mima l’attività della GPx. Essi sembrano inoltre evidenziare che il “meccanismo antiossidante” sia mediato sostanzialmente dall’attività GPx mentre non sono particolarmente attivi meccanismi di radical scavenging né di puro trasferimento elettronico. Alcuni dei Sec-derivati sintetizzati sono stati oggetto di un’indagine cellulare preliminare volta a verificare una eventuale effettiva azione protettiva dei calco-diamminoacidi verso il danno cellulare indotto da AFB1. Le indagini sono state effettuate adoperando una linea cellulare HepG2. I dati ottenuti, nel loro insieme, hanno mostrato che i calco-diamminoacidi esaminati sono di per sé caratterizzati da una notevole attività biologica. In particolare, alla concentrazione più elevata utilizzata (100 µM), alcuni di essi hanno mostrato interessanti proprietà citoprotettive contro il danno indotto da AFB1. L’efficacia è paragonabile, e in qualche caso superiore, a quella riscontrabile per il composto di riferimento, la Se-metil-selenocisteina, principale forma di selenio organico che è naturalmente presente in specie vegetali quali Allium Sativum e Brassica juncea.
Mycotoxin contamination may involve all fields of the food agricultural chain and might potentially determine economic losses. In particular, the livestock sector is at risk of health costs, as a consequence of chronic diseases induced by mycotoxin exposure. It is obvious, although actual, that the mycotoxin contamination should be controlled on the field by a series of suitable agriculture practices in order to minimize the mycotoxin formation in feeds. Recently, dietary strategies (antioxidant compounds, medicinal herbs, plant extracts) to counteract the effects of mycotoxins have attracted considerable attention. Chemoprevention refers to the use of naturally occuring and/or synthetic chemicals to inhibit the development of mycotoxin induced chronic diseases. Selenium and its organic and inorganic compounds, have emerged as outstanding chemoprevention agents. Selenium antineoplastic properties have been well documented through the last decades, being supported by several epidemiological evidences on the association between selenium intake and the risk for some kinds of human/animal cancers. This PhD thesis was focussed on design, synthesis and study of a family of chalcogenic diamino acids (containing either selenium or sulfur), GPx mimics and potentially active to reduce the oxidative damage induced by aflatoxin B1 (AFB1). The diamino acids synthesized belong to the family of Sec-derivatives and consist of L-selenocysteine (or L-cysteine) linked through the calchogen atom to either a L-proline or a L-leucine moiety. The GPx-like catalytic activity of the various compounds was confirmed using both thiophenol and GPx assays. Their possible radical-scavenging activity, and electron-donor reducing character as well, could be ruled out by suitable assays. The cytoprotective capacity exhibited by several of the compounds synthesized was investigated in HepG2 cells by MTS assays. The results indicated that all the chalcogenic diamino acids tested had a strong biological activity. In particular, the pre-treatment of the test cells with two Sec-derivatives, employed at higher doses (100 µM), led to a protective effect on cell toxicity, lowering the AFB1-induced cell mortality, and this efficacy is comparable with that of the reference Se-metil-selenocysteine, main source of organic selenium in plants such as Allium Sativum and Brassica juncea.

La contaminazione da micotossine può coinvolgere tutti i comparti della filiera agroalimentare e rappresenta a tutti gli effetti un potenziale di perdita economica. Il settore zootecnico è particolarmente esposto alle ricadute della contaminazione, in termini di costi sanitari per gli effetti cronici sulla salute animale conseguenti all’esposizione alle micotossine. La prevenzione in campo mediata da appropriate tecniche agronomiche rappresenta, per quanto ovvio, la più importante strategia per ridurre la contaminazione dei mangimi. Un approccio completamente differente è quello che si basa sulla possibilità di ridurre gli effetti delle tossine sull’animale, modificando la sua alimentazione attraverso l’integrazione nutrizionale di opportuni agenti chemiopreventivi. Numerose sono le specie chimiche, di origine naturale o sintetica, che hanno dimostrato una efficacia chemiopreventiva del danno ossidativo indotto da micotossine ed emergono per la loro efficacia il selenio e i suoi composti organici ed inorganici. L’azione antineoplastica del selenio è nota da molto tempo e ha trovato conferme in numerosi studi epidemiologici che indicano una relazione inversa tra assunzione di selenio con la dieta e rischio di sviluppo di una patologia neoplastica. Questa tesi di dottorato ha avuto come obiettivo la progettazione, la sintesi e lo studio di composti diamminoacidici contenenti un atomo di calcogeno (selenio o zolfo), mimici dalla glutatione perossidasi (GPx) e auspicabilmente attivi nel contrasto del danno ossidativo indotto dall’aflatossina B1 (AFB1). Le specie diamminoacidiche sintetizzate appartengono alla classe dei Sec-derivati, ovvero sono costitute da un residuo di L-selenocisteina (o L-cisteina) a cui è legato attraverso l’atomo di calcogeno un altro L-amminoacido. Alla porzione calcogenica, che rappresenta il sito redox, sono stati infatti ancorati rispettivamente un residuo di L-prolina modificata e un residuo di L-leucina. Al termine delle fasi di sintesi e caratterizzazione chimico-fisica dei calco-diamminoacidi è stata intrapresa una serie di indagini biochimiche in collaborazione con due distinti laboratori in Germania. I risultati ottenuti hanno permesso di dimostrare che alcuni Sec-derivati sono in grado di ridurre i perossidi attraverso un meccanismo catalitico che mima l’attività della GPx. Essi sembrano inoltre evidenziare che il “meccanismo antiossidante” sia mediato sostanzialmente dall’attività GPx mentre non sono particolarmente attivi meccanismi di radical scavenging né di puro trasferimento elettronico. Alcuni dei Sec-derivati sintetizzati sono stati oggetto di un’indagine cellulare preliminare volta a verificare una eventuale effettiva azione protettiva dei calco-diamminoacidi verso il danno cellulare indotto da AFB1. Le indagini sono state effettuate adoperando una linea cellulare HepG2. I dati ottenuti, nel loro insieme, hanno mostrato che i calco-diamminoacidi esaminati sono di per sé caratterizzati da una notevole attività biologica. In particolare, alla concentrazione più elevata utilizzata (100 µM), alcuni di essi hanno mostrato interessanti proprietà citoprotettive contro il danno indotto da AFB1. L’efficacia è paragonabile, e in qualche caso superiore, a quella riscontrabile per il composto di riferimento, la Se-metil-selenocisteina, principale forma di selenio organico che è naturalmente presente in specie vegetali quali Allium Sativum e Brassica juncea.
Mycotoxin contamination may involve all fields of the food agricultural chain and might potentially determine economic losses. In particular, the livestock sector is at risk of health costs, as a consequence of chronic diseases induced by mycotoxin exposure. It is obvious, although actual, that the mycotoxin contamination should be controlled on the field by a series of suitable agriculture practices in order to minimize the mycotoxin formation in feeds. Recently, dietary strategies (antioxidant compounds, medicinal herbs, plant extracts) to counteract the effects of mycotoxins have attracted considerable attention. Chemoprevention refers to the use of naturally occuring and/or synthetic chemicals to inhibit the development of mycotoxin induced chronic diseases. Selenium and its organic and inorganic compounds, have emerged as outstanding chemoprevention agents. Selenium antineoplastic properties have been well documented through the last decades, being supported by several epidemiological evidences on the association between selenium intake and the risk for some kinds of human/animal cancers. This PhD thesis was focussed on design, synthesis and study of a family of chalcogenic diamino acids (containing either selenium or sulfur), GPx mimics and potentially active to reduce the oxidative damage induced by aflatoxin B1 (AFB1). The diamino acids synthesized belong to the family of Sec-derivatives and consist of L-selenocysteine (or L-cysteine) linked through the calchogen atom to either a L-proline or a L-leucine moiety. The GPx-like catalytic activity of the various compounds was confirmed using both thiophenol and GPx assays. Their possible radical-scavenging activity, and electron-donor reducing character as well, could be ruled out by suitable assays. The cytoprotective capacity exhibited by several of the compounds synthesized was investigated in HepG2 cells by MTS assays. The results indicated that all the chalcogenic diamino acids tested had a strong biological activity. In particular, the pre-treatment of the test cells with two Sec-derivatives, employed at higher doses (100 µM), led to a protective effect on cell toxicity, lowering the AFB1-induced cell mortality, and this efficacy is comparable with that of the reference Se-metil-selenocysteine, main source of organic selenium in plants such as Allium Sativum and Brassica juncea.

Abstract With the development of intelligent vehicle driving, the vehicles must be trained through deep learning method. Therefore, the vehicles will be driven on real roads and subjected to traffic and environmental conditions, such as traffic lights, traffic jams, rounds, stops, curves, road condition and gradient. The on-road driving tests make it difficult to predefine beforehand the route, since the conditions are changeable and unpredictable. On the other hand, it is quite time-consuming and expensive. However, the generation of methods and algorithms able to read the main important parameters from the route (speed and gradient profile) would give a twofold benefit: generation and optimization or appropriate routes considering the testing objective, and if a powertrain model available, simulation of vehicle performance and emissions. In such a context, this thesis aims to generate real driving speed profiles based on either Google Maps guidance or GPX experiment data, considering speed limit, curvature and traffic condition. Real driving cycle generation from the on-line platform Google Maps and GPX data shows advantage over traditional experimental data characterization in aspects of cost, universality and convenience. Based on this approach, it is possible to analyze the influence of driver characteristics, curvature and traffic condition on driving behavior, emissions and fuel consumption, supporting in the phase of intelligent vehicle strategy development. The generated profile is compared to real driving recorded GPX data and is verified to be generally realistic.

Ground-penetrating radar (GPR) is a nondestructive geophysical technique used to create images of the subsurface. A major limitation of GPR is that a subject matter expert (SME) needs to post-process and interpret the data, limiting the technique’s use. Post-processing is time-intensive and, for detailed processing, requires proprietary software. The goal of this study is to develop automated GPR post-processing software, compatible with Geophysical Survey Systems, Inc. (GSSI) data, in open-source R programming. This would eliminate the need for an SME to process GPR data, remove proprietary software dependencies, and render GPR more accessible. This study collected GPR profiles by using a GSSI SIR4000 control unit, a 100 MHz antenna, and a Trimble GPS. A standardized method for post-processing data was then established, which includes static data removal, time-zero correction, distance normalization, data filtering, and stacking. These steps were scripted and automated in R programming, excluding data filtering, which was used from an existing package, RGPR. The study compared profiles processed using GSSI software to profiles processed using the R script developed here to ensure comparable functionality and output. While an SME is currently still necessary for interpretations, this script eliminates the need for one to post-process GSSI GPR data.

The McMurdo shear zone (MSZ) is strip of heavily crevassed ice oriented in the south-north direction and moving northward. Previous airborne surveys revealed a chaotic crevasse structure superimposed on a set of expected crevasse orientations at 45 degrees to the south-north flow (due to shear stress mechanisms). The dynamics that produced this chaotic structure are poorly understood. Our purpose is to present our field methodology and provide field data that will enable validation of models of the MSZ evolution, and here, we present a method for deriving a local velocity field from ground penetrating radar (GPR) data towards that end. Maps of near-surface crevasses were derived from two annual GPR surveys of a 28 km² region of the MSZ using Eulerian sampling. Our robot-towed and GPS navigated GPR enabled a dense survey grid, with transects of the shear zone at 50 m spacing. Each survey comprised multiple crossings of long (> 1 km) crevasses that appear in echelon on the western and eastern boundaries of the shear zone, as well as two or more crossings of shorter crevasses in the more chaotic zone between the western and eastern boundaries. From these maps, we derived a local velocity field based on the year-to-year movement of the same crevasses. Our velocity field varies significantly from fields previously established using remote sensing and provides more detail than one concurrently derived from a 29-station GPS network. Rather than a simple velocity gradient expected for crevasses oriented approximately 45 degrees to flow direction, we find constant velocity contours oriented diagonally across the shear zone with a wavy fine structure. Although our survey is based on near-surface crevasses, similar crevassing found in marine ice at 160 m depth leads us to conclude that this surface velocity field may hold through the body of meteoric and marine ice. Our success with robot-towed GPR with GPS navigation suggests we may greatly increase our survey areas.

The National Science Foundation operates stations on the ice sheets of Antarctica and Greenland to investigate Earth’s climate history, life in extreme environments, and the evolution of the cosmos. Understandably, logistics costs predominate budgets due to the remote locations and harsh environments involved. Currently, manual ground-penetrating radar (GPR) surveys must preceed vehicle travel across polar ice sheets to detect subsurface crevasses or other voids. This exposes the crew to the risks of undetected hazards. We have developed an autonomous rover, Yeti, specifically to conduct GPR surveys across polar ice sheets. It is a simple four-wheel-drive, battery-powered vehicle that executes autonomous surveys via GPS waypoint following. We describe here three recent Yeti deployments, two in Antarctica and one in Greenland. Our key objective was to demonstrate the operational value of a rover to locate subsurface hazards. Yeti operated reliably at −30 ◦C, and it has good oversnow mobility and adequate GPS accuracy for waypoint-following and hazard georeferencing. It has acquired data on hundreds of crevasse encounters to improve our understanding of heavily crevassed traverse routes and to develop automated crevasse-detection algorithms. Importantly, it helped to locate a previously undetected buried building at the South Pole. Yeti can improve safety by decoupling survey personnel from the consequences of undetected hazards. It also enables higher-quality systematic surveys to improve hazard-detection probabilities, increase assessment confidence, and build datasets to understand the evolution of these regions. Yeti has demonstrated that autonomous vehicles have great potential to improve the safety and efficiency of polar logistics.