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Arsenic in natural waters: hydrogeochemistry characterization and toxicity effects
Doroteja Gošar, 2018, magistrsko delo

Opis: Arsenic contamination in natural water is a worldwide problem and a major health concern. In master thesis hydrogeochemistry and toxicity effects of natural waters rich in arsenic were studied. The main objective of the master thesis was to evaluate As pollution of the Freixeda stream and groundwater in abandoned Freixeda gold mine area in NE Portugal near Mirandela city (41.413767 N 7.103562 W) and compare it with the data from previous studies. Further on, toxicological evaluation of selected water samples was performed in the in vitro system of human cell line Caco-2. Chemical analyses of sampled water samples with use of different modelling sofware show that groundwater have higher sulphate and bicarbonate values than surface water, which could be the reason for As desorption and higher As values in groundwater. Water-rock interaction promotes reduction and dissolution of sulphide minerals and in reductive environments dissolution of secondary Fe minerals releases adsorbed As into solution. Toxicological testing on human cells included cytotoxicity assay, genotoxicity assay and production of reactive oxigene species (ROS). Genotoxicity was only modestly affected by a short-term exposure to As-contaminated water samples, however, higher concentrations of As in real samples lead to higher level of oxidative stress and decreased cell viability. Exposure of cells to pure As(III) solution show clear concentration dependent decrease in cell metabolism and viability, strong genotoxicity and increased ROS generation. Considering the worldwide extent of As contamination in natural waters and ability of intestinal epithelium to reduce the potential harmful effects of As, more studies evaluating the human intestinal permeability for As should be done in the future.
Najdeno v: osebi
Ključne besede: Water quality, arsenic, hydrogeochemistry, toxicity, Caco-2 cell line
Objavljeno: 26.09.2018; Ogledov: 808; Prenosov: 54
.pdf Polno besedilo (3,76 MB)

17.
DOLOČANJE ACETILHOLINESTERAZE V HUMANIH KRVNIH VZORCIH
Tjaša Birsa, 2018, magistrsko delo

Opis: V strokovni literaturi zasledimo encim acetilholinesterazo (AChE) v različnih raziskavah s področja okoljevarstva, medicine in veterine. Zmanjšana encimska aktivnost je lahko indikator onesnaženosti okolja z organofosfatnimi in karbamatnimi pesticidi, policikličnimi aromatskimi ogljikovodiki ter težkimi kovinami. Spremembe v encimski aktivnosti AChE pa so tudi biološki označevalec nekaterih nevrodegenerativnih bolezni pri človeku. V človeškem telesu se encim AChE primarno nahaja v živčnem sistemu, najdemo pa ga tudi v krvi, zlasti v membranah eritrocitov. V krvi je v večji meri prisoten tudi encim butirilholinesteraza (BChE), ki ravno tako spada v družino holinesteraz. Naš cilj je bil razviti metodo, ki bi omogočala specifično merjenje encimske aktivnosti AChE v okviru celotnih holinesteraz v krvnem serumu. Za merjenje encimske aktivnosti smo uporabili Ellmanovo metodo. Količino obarvanih produktov reakcije smo določali s spektroskopijo s toplotnimi lečami TLS in z UV-VIS spektrofotometrijo. Z različnimi koncentracijami čistega encima AChE smo najprej določili mejo zaznavnosti obeh metod (LOD). Detekcija s TLS je bila bolj občutljiva, saj je bil LOD 3,13-krat manjši kot pri detekciji z UV-VIS. Potem smo izmerili encimsko aktivnost celotnih holinesteraz AChE in BChE v serumskih vzorcih zdravih ljudi. Izračunana encimska aktivnost holinesteraz se je v analiziranih vzorcih gibala med 3004 mU mL-1 in 5698 mU mL-1. Po dodatku specifičnega inhibitorja BChE se je celotna encimska aktivnost znižala za najmanj 60 %, kar kaže, da večina holinesteraz v krvnem serumu pripada BChE. Preizkusili smo tudi metodo enojne imunske precipitacije, vendar se je le-ta izkazala za neuspešno pri ločevanju posameznih holinesteraz iz serumskih vzorcev. Na podlagi naših rezultatov smo prišli do zaključka, da je za merjenje encimske aktivnosti posameznih holinesteraz AChE in BChE v krvnem serumu najprimernejša uporaba specifičnih inhibitorjev, vendar bi bilo to metodo potrebno še dodatno optimizirati.
Najdeno v: osebi
Ključne besede: acetilholinesteraza, krvni serum, nevrodegenerativne bolezni, spektroskopija s toplotnimi lečami, UV-VIS spektrofotometrija, imunska precipitacija.
Objavljeno: 07.11.2018; Ogledov: 653; Prenosov: 49
.pdf Polno besedilo (1,65 MB)

18.
Vpliv proteinov APOBEC na infekcijo z virusi HPV
Tjaša Lojpur, 2018, magistrsko delo

Opis: Humani virusi papiloma (HPV) so povzročitelji najpogostejše spolno prenosljive okužbe, povezani pa so tudi z razvojem raka materničnega vratu. Proteini APOBEC so DNA/RNA editirajoči encimi, ki igrajo ključno vlogo pri prirojenih protivirusnih imunskih odzivih in so vpleteni tako v infekcijo s HPV kot tudi v razvoj rakavih obolenj pri dolgotrajni okužbi s HPV. Glavni cilj magistrskega dela je bil proučiti protivirusno delovanje proteinov APOBEC in določiti tudi ožji nabor proteinov APOBEC, vključenih v protivirusni odziv pri infekciji s HPV. Vpliv proteinov APOBEC na primarno infekcijo smo ugotavljali z uporabo psevdovirusnih delcev (PsV) HPV, v plašču katerih je bil vgrajen reporterski gen za luciferazo. Stopnjo infekcije virusov HPV v gostiteljskih celičnih linijah, transficiranih s proteini hAPOBEC, smo določali posredno preko encimske aktivnosti luciferaze. Ugotovili smo, da izražanje večine proteinov hAPOBEC zniža infektivnost PsV HPV. Izmed proučevanih proteinov hAPOBEC so imeli najmočnejši protivirusni odziv hAID, hA1, hA2, hA3A, hA3B, hA3C in hA3DE, saj so zmanjšali infektivnost PsV HPV-16 za več kot 50 %. Čeprav smo protivirusni učinek proteinov hAPOBEC ugotovili tudi pri dveh kožnih tipih, HPV-2 in HPV-5, je bil le ta značilno višji pri visokorizičnem sluzničnem tipu HPV-16. Mehanizme delovanja proteinov hAPOBEC smo ugotavljali s katalitskimi in nekatalitskimi mutantami proteinov hA3A (E72A) in hA3B (E255Q in E68Q), ki so za razliko od divjih tipov, infektivnost HPV-16 povečale. Mikroskopska analiza znotrajcelične lokalizacije izbranih proteinov hAPOBEC med infekcijo s HPV-16 pa je pokazala, da se 24 ur po infekciji zgodi premik deleža proteina hA3A iz citoplazme v jedro, kar bi lahko vplivalo na potek infekcije. V magistrskem delu smo potrdili prvotno hipotezo, da proteini APOBEC sodelujejo pri protivirusnem odzivu virusov HPV, njihov protivirusni učinek pa je odvisen tako od vrste proteina APOBEC kot tudi od tipa virusa HPV.
Najdeno v: osebi
Ključne besede: HPV, proteini APOBEC, protivirusni odziv, infektivnost, znotrajcelična lokalizacija
Objavljeno: 05.11.2018; Ogledov: 740; Prenosov: 52
.pdf Polno besedilo (1,64 MB)

19.
Characterization of lactic bacteria for biogenic amine formation
Branka Mozetič Vodopivec, Martina Bergant Marušič, Jelena Topić, Dorota Korte, Lorena Butinar, 2018, samostojni znanstveni sestavek ali poglavje v monografski publikaciji

Opis: Biogenic amines are compounds present in many different foods and beverages (wine, beer, dairy products, fermented vegetables and soy products, fish, etc.). Their presence in foodstuff is a result of a microbial action during storage and ageing. The most important are histamine, tryptamine, β-phenylethylamine and tryptamine, which can induce undesirable physiological effects in humans. They are formed through decarboxylation of corresponding amino acids, through the action of enzymes. Consumption of food containing biogenic amines can lead to food poisoning such as histamine poisoning. Histamine, the most studied biogenic amine, is known to cause headaches, oedema, vomiting, etc. [1]–[4]. Monitoring of the content of biogenic amines in foods is of concern for public health in their relation to the food safety, food spoilage and food intolerance. Because microorganisms are used in food productions as starters and biopreservers, characterization of microorganisms for their ability to produce biogenic amines is equally important. Lactic acid bacteria are often used as biopreservers as they can produce antimicrobial metabolites and antifungal peptides. Some strains can also produce undesirable biogenic amines [5]. In order to use lactic acid bacteria as starters or biopreservers, the selection of strains that would not produce biogenic amines is necessary. When considering studies of biogenic amines in foods, focus should be on developing new or improving analysis methods for biogenic amines detection. Secondly, the connections between microorganisms capable of producing biogenic amines and the content of biogenic amines in foods should be investigated [3]. The most widely technique used for quantification of biogenic amines in foodstuff is liquid chromatography, Alternatively to chromatographic techniques, other techniques such as enzymatic biosensors, ELISA and flow-injection analysis have also been employed. Sensors are interesting due to the fact that they do not require special instrumentations, and there is no need for sample clean-up and derivatization, which are the main drawback of chromatographic methods [4]. Detection of biogenic amines producing lactic bacteria is important due to the concerns for public health and there is a need for the early and rapid detection of such microorganisms. Most of the methods that are used for screening involved the measurement of amino acid-decarboxylase activity, although there were been some methods reported that used differential media and pH indicators. Nowadays, molecular methods are replacing culture methods. Molecular approaches are used to determine the presence or absence of genes responsible for biogenic amines formation. The main advantages of DNA hybridization and PCR methods are speed, simplicity, sensitivity and specificity as they allow detection of targeted genes. Culture independent methods which are based on PCR techniques are now regarded as most suitable methods for screening isolates [5]. [1] A. R. Shalaby, “Significance of biogenic amines to food safety and human health,” Food Res. Int., vol. 29, no. 7, pp. 675–690, Oct. 1996. [2] J. M. Landete, S. Ferrer, and I. Pardo, “Biogenic amine production by lactic acid bacteria, acetic bacteria and yeast isolated from wine,” Food Control, vol. 18, pp. 1569–1574, 2007. [3] F. B. Erim, “Recent analytical approaches to the analysis of biogenic amines in food samples,” TrAC - Trends in Analytical Chemistry, vol. 52. pp. 239–247, 2013. [4] J. L. Ordóñez, A. M. Troncoso, M. D. C. García-Parrilla, and R. M. Callejón, “Recent trends in the determination of biogenic amines in fermented beverages – A review,” Analytica Chimica Acta, vol. 939. pp. 10–25, 2016. [5] R. M. Elsanhoty and M. F. Ramadan, “Genetic screening of biogenic amines production capacity from some lactic acid bacteria strains,” Food Control, vol. 68, pp. 220–228, Oct. 2016.
Najdeno v: osebi
Ključne besede: lactic bacteria, biogenic amines
Objavljeno: 13.12.2018; Ogledov: 433; Prenosov: 0
.pdf Polno besedilo (504,99 KB)

20.
Phosphorylation of HPV-16 L2 Contributes To Efficient Virus Infectious Entry
Robert L. Garcea, Michael P. Myers, Martina Bergant Marušič, David Pim, Paola Massimi, Justyna Broniarczyk, Lawrence Banks, 2019, izvirni znanstveni članek

Opis: The Human Papillomavirus (HPV) capsid comprises two viral proteins, L1 and L2, with the L2 component being essential to ensure efficient endocytic transport of incoming viral genomes. Several studies have previously reported that L1 and L2 are post-translationally modified, but it is uncertain whether these modifications affect HPV infectious entry. Using a proteomic screen, we identified a highly conserved phospho-acceptor site on the HPV-16 and BPV-1 L2 proteins. The phospho-modification of L2, and its presence in HPV pseudovirions (PsVs), was confirmed using anti-phospho L2-specific antibodies. Mutation of the phospho-acceptor sites of both HPV-16 and BPV-1 L2 resulted in the production of infectious virus particles, with no differences in efficiency of packaging the reporter DNA. However, these mutated PsVs showed marked defects in infectious entry. Further analysis revealed a defect in uncoating, characterized by a delay in the exposure of a conformational epitope on L1 that indicates capsid uncoating. This uncoating defect was accompanied by a delay in the proteolysis of both L1 and L2 in mutated HPV-16 PsVs. Taken together, these studies indicate that phosphorylation of L2 during virus assembly plays an important role in optimal uncoating of virions during infection, suggesting that phosphorylation of the viral capsid proteins contributes to infectious entry.
Najdeno v: osebi
Ključne besede: HPV, L2, infection, protein phosphorylation
Objavljeno: 05.06.2019; Ogledov: 372; Prenosov: 0
.pdf Polno besedilo (1,70 MB)

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