Repozitorij Univerze v Novi Gorici

Iskanje po repozitoriju
A+ | A- | Pomoč | SLO | ENG

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


1 - 10 / 13
Na začetekNa prejšnjo stran12Na naslednjo stranNa konec
1.
RAPID UPLC-ESI-MS/MS BASED ASSAY FOR DISCOVERY OF UDP-N-ACETYLMURAMOYL-L-ALANINE:D-GLUTAMATE (MurD) LIGASE INHIBITORS
Vjekoslava Car, 2016, magistrsko delo

Opis: A rapid, selective, robust and sensitive analytical assay method, operating in a short time frame with acceptable levels of precision, linear range and the accuracy necessary for successful Mur ligases inhibitors discovery, was developed. An LC-MS/MS analytical procedure was designed for the determination of a MurD ligase reaction product (UMAG). The special focus of this work was on UDP-N-acetylmuramyl-L-alanine:D-glutamate ligase (MurD) activity. The assay method is especially valuable as an orthogonal (secondary) assay for the primary high throughput fluorescent-based assay screening of potential Mur ligase inhibitors. The LC-MS/MS assay is fully compatible with the components from the primary fluorescent-based assay and enables the analysis of the same samples by both methodologies. The presented LC-MS/MS assay procedure is used for the evaluation of the false positive hits (molecules) from the primary, fluorescence based, high throughput screening assay experiments. This is important for the elimination of false positive hits from the prohibitively expensive and time-consuming investigation process. Method development describes the evaluation and optimization of the various stages of sample preparation, chromatographic separation, MS/MS determination and quantification. An enzyme reaction is performed in a 96-well plate. The quenched reaction mixture samples were spiked with an internal standard (phenacetin). The permeate was injected onto the U(H)PLC-MS/MS triple quadrupole system after sample ultrafiltration. Chromatographic separation was achieved on the ACQUITY UPLCTM HSS T3 column (100 x 2.1 mm i.d., 1.8 µm particle size) using an ammonium format buffer at pH 2.8 and acetonitrile as eluent. Elution initiated with an isocratic-hold for 1.1 min, followed by a two-step linear gradient of up to 3 min, giving a total run time of 5 min including equilibration. The flow rate was kept at a constant 0.4 mL/min. UMAG quantitative analysis was performed by positive electrospray ionization, followed by tandem mass spectrometry (ESI-MS/MS). The analytical assay quantifies UMAG in a linear range from 0.25 to 20 µM using 70 µL of samples. Validation results demonstrated that UMAG concentrations can be accurately and precisely determined in samples from the primary assay. Evaluation of inhibitory activities of compounds measured by both the fluorescence and the LC-MS/MS method demonstrated that the values were in a very good agreement. This analytical method can be used to screen a compound library at a defined concentration of each compound to obtain the percentage of inhibition, or with a series of compound concentrations to obtain inhibition potency of a compound (IC50). The selected Lek compounds no. 1 and 2 from the virtual screening campaign were presented, tested and further investigated due to the expression of significant MurD ligase inhibitory action acquired by primary high throughput tests. This assay has been developed for MurD, but during development, chromatographic and MS/MS conditions for UM and UMA were studied and defined as well. Therefore, this analytical assay method can easily be applied to other Mur ligases (i.e. MurC, MurE) enzyme activity monitoring in the process of bacteria cell wall peptidoglycan formation. This method enables the identification of many different Mur ligase inhibitors in a continued search for new Gram positive and Gram negative bacteria antibiotics.
Najdeno v: ključnih besedah
Povzetek najdenega: ...by positive electrospray ionization, followed by tandem mass spectrometry (ESI-MS/MS). The analytical assay quantifies UMAG...
Ključne besede: Mur ligases, UDP-N-acetylmuramyl-L-alanine:D-glutamate (MurD) inhibitors, UNAM-Ala-Glu, LC-MS/MS, liquid chromatography, tandem mass spectrometry, antibiotics, drug discovery
Objavljeno: 23.09.2016; Ogledov: 4628; Prenosov: 221
.pdf Polno besedilo (2,62 MB)

2.
Development and Validation of a High- Performance Liquid Chromatography– Tandem Mass Spectrometry Method for the Simultaneous Determination of Irinotecan and Its Main Metabolites in Human Plasma and Its Application in a Clinical Pharmacokinetic Study
Giuseppe Toffoli, Elena Marangon, Elisa Mazzega, Bianca Posocco, 2015, izvirni znanstveni članek

Opis: Irinotecan is currently used in several cancer regimens mainly in colorectal cancer (CRC). This drug has a narrow therapeutic range and treatment can lead to side effects, mainly neutropenia and diarrhea, frequently requiring discontinuing or lowering the drug dose. A wide inter-individual variability in irinotecan pharmacokinetic parameters and pharmacodynamics has been reported and associated to patients’ genetic background. In particular, a polymorphism in the UGT1A1 gene (UGT1A1*28) has been linked to an impaired detoxification of SN-38 (irinotecan active metabolite) to SN-38 glucuronide (SN-38G) leading to increased toxicities. Therefore, therapeutic drug monitoring of irinotecan, SN-38 and SN-38G is recommended to personalize therapy. In order to quantify simultaneously irinotecan and its main metabolites in patients’ plasma, we developed and validated a new, sensitive and specific HPLC–MS/MS method applicable to all irinotecan dosages used in clinic. This method required a small plasma volume, addition of camptothecin as internal standard and simple protein precipitation. Chromatographic separation was done on a Gemini C18 column (3 μM, 100 mm x 2.0 mm) using 0.1% acetic acid/bidistilled water and 0.1% acetic acid/acetonitrile as mobile phases. The mass spectrometer worked with electrospray ionization in positive ion mode and selected reaction monitoring. The standard curves were linear (R20.9962) over the concentration ranges (10–10000 ng/mL for irinotecan, 1–500 ng/mL for SN-38 and SN-38G and 1–5000 ng/mL for APC) and had good back-calculated accuracy and precision. The intra- and inter-day precision and accuracy, determined on three quality control levels for all the analytes, were always <12.3% and between 89.4% and 113.0%, respectively. Moreover, we evaluated this bioanalytical method by re-analysis of incurred samples as an additional measure of assay reproducibility. This method wassuccessfully applied to a pharmacokinetic study in metastatic CRC patients enrolled in a genotype-guided phase Ib study of irinotecan administered in combination with 5-fluorouracil/ leucovorin and bevacizumab.
Najdeno v: ključnih besedah
Ključne besede: Pharmacokinetic, pharmacodynamics, phase I clinical study, colorectal cancer, Mass spectrometry, pharmacogenetics
Objavljeno: 21.03.2017; Ogledov: 2713; Prenosov: 0
.pdf Polno besedilo (1018,06 KB)

3.
Stable carbon isotope analysis of selected halocarbons at parts per trillion concentration in an urban location
M Iqbal Mead, M Anwar H Khan, Ian D Bull, Iain R White, Graham Nickless, Dudley E Shallcross, 2008, izvirni znanstveni članek

Opis: ∂13C values of a suite of halocarbons have been determined in an urban background site in Bristol, UK. A novel mobile preconcentration system, based on the use of multi-adsorbent sample tubes, has been developed for trapping relatively large-volume air samples in potentially remote areas. An Adsorption Desorption System-Gas Chromatography-Electron Capture Detector was used to measure the mixing ratios of the selected halocarbon species, while a Gas ChromatographyCombustionIsotope Ratio Mass Spectrometer was used to determine ∂13C values. For the species with strong local sources, the variation of isotope ratios has been observed over the experimental period. Some of the results reported in the present study differ from previously reported values and reasons for this are discussed. The reporting of different ∂13C values for selected halocarbons from different areas in the present study suggests that ∂13C values may be used to determine the relative magnitudes of anthropogenic and biogenic sources.
Najdeno v: ključnih besedah
Povzetek najdenega: ...halocarbon species, while a Gas ChromatographyCombustionIsotope Ratio Mass Spectrometer was used to determine ∂13C values.... ...(ECD), Gas Chromatography (GC), Isotope Ratio Mass Spectrometry (IRMS)...
Ključne besede: Adsorption Desorption System (ADS), Automated Thermal Desorber (ATD), Electron Capture Detector (ECD), Gas Chromatography (GC), Isotope Ratio Mass Spectrometry (IRMS)
Objavljeno: 18.07.2019; Ogledov: 1432; Prenosov: 0
.pdf Polno besedilo (227,35 KB)

4.
Increased sensitivity in proton transfer reaction mass spectrometry by incorporation of a radio frequency ion funnel
Andrew M Ellis, Stephen Mullock, Fraser Reich, Paul S Monks, Iain R White, Robert S Blake, Shane Barber, 2012, izvirni znanstveni članek

Opis: A drift tube capable of simultaneously functioning as an ion funnel is demonstrated in proton transfer reaction mass spectrometry (PTR-MS) for the first time. The ion funnel enables a much higher proportion of ions to exit the drift tube and enter the mass spectrometer than would otherwise be the case. An increase in the detection sensitivity for volatile organic compounds of between 1 and 2 orders of magnitude is delivered, as demonstrated using several compounds. Other aspects of analytical performance explored in this study include the effective E/N (ratio of electric field to number density of the gas) and dynamic range over which the drift tube is operated. The dual-purpose drift tube/ion funnel can be coupled to various types of mass spectrometers to increase the detection sensitivity and may therefore offer considerable benefits in PTR-MS work.
Najdeno v: ključnih besedah
Ključne besede: Analytical performance, Detection sensitivity, Drift tube, Dynamic range, Ion funnels, Proton-transfer reaction mass spectrometry, Volatile organic compounds
Objavljeno: 18.07.2019; Ogledov: 1344; Prenosov: 0
.pdf Polno besedilo (799,47 KB)

5.
Real-time multi-marker measurement of organic compounds in human breath: Towards fingerprinting breath
Iain R White, Kerry A Willis, Christopher Whyte, Rebecca Cordell, Robert S Blake, Andrew J Wardlaw, 2013, izvirni znanstveni članek

Opis: The prospects for exploiting proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS) in medical diagnostics are illustrated through a series of case studies. Measurements of acetone levels in the breath of 68 healthy people are presented along with a longitudinal study of a single person over a period of 1 month. The median acetone concentration across the population was 484 ppbV with a geometric standard deviation (GSD) of 1.6, whilst the average GSD during the single subject longtitudinal study was 1.5. An additional case study is presented which highlights the potential of PTR-ToF-MS in pharmacokinetic studies, based upon the analysis of online breath samples of a person following the consumption of ethanol. PTR-ToF-MS comes into its own when information across a wide mass range is required, particularly when such information must be gathered in a short time during a breathing cycle. To illustrate this property, multicomponent breath analysis in a small study of cystic fibrosis patients is detailed, which provides tentative evidence that online PTR-ToF-MS analysis of tidal breath can distinguish between active infection and non-infected patients.
Najdeno v: ključnih besedah
Povzetek najdenega: ...prospects for exploiting proton transfer reaction-time of flight- mass spectrometry (PTR-ToF-MS) in medical diagnostics are illustrated...
Ključne besede: Volatile Organic Compounds, breath, proton transfer reaction mass spectrometry, Cystic Fibrosis
Objavljeno: 22.07.2019; Ogledov: 1556; Prenosov: 0
.pdf Polno besedilo (1,37 MB)

6.
Observations of the release of non-methane hydrocarbons from fractured shale
Roberto Sommariva, Robert S Blake, Robert J Cuss, Rebecca L Cordell, Jon F Harrington, Iain R White, Paul S Monks, 2014, izvirni znanstveni članek

Opis: The organic content of shale has become of commercial interest as a source of hydrocarbons, owing to the development of hydraulic fracturing ("fracking"). While the main focus is on the extraction of methane, shale also contains significant amounts of non-methane hydrocarbons (NMHCs). We describe the first real-time observations of the release of NMHCs from a fractured shale. Samples from the Bowland-Hodder formation (England) were analyzed under different conditions using mass spectrometry, with the objective of understanding the dynamic process of gas release upon fracturing of the shale. A wide range of NMHCs (alkanes, cycloalkanes, aromatics, and bicyclic hydrocarbons) are released at parts per million or parts per billion level with temperature- and humidity-dependent release rates, which can be rationalized in terms of the physicochemical characteristics of different hydrocarbon classes. Our results indicate that higher energy inputs (i.e., temperatures) significantly increase the amount of NMHCs released from shale, while humidity tends to suppress it; additionally, a large fraction of the gas is released within the first hour after the shale has been fractured. These findings suggest that other hydrocarbons of commercial interest may be extracted from shale and open the possibility to optimize the "fracking" process, improving gas yields and reducing environmental impacts.
Najdeno v: ključnih besedah
Povzetek najdenega: ...(England) were analyzed under different conditions using mass spectrometry, with the objective of understanding the...
Ključne besede: Environmental impact, Hydraulic fracturing, Mass spectrometry
Objavljeno: 18.07.2019; Ogledov: 1354; Prenosov: 0
.pdf Polno besedilo (2,47 MB)

7.
TD/GC–MS analysis of volatile markers emitted from mono- and co-cultures of Enterobacter cloacae and Pseudomonas aeruginosa in artificial sputum
Craig Portsmouth, Pedro Povoa, Jan H Leopold, Pouline M P van Oort, Emili Diaz, Gemma Goma, Timothy Felton, Paul Dark, Alan Davie, Luis Coelho, Lieuwe D Bos, Marta Camprubi, Antonio Artigas, Jonathan Barnard-Smith, Waqar M Ahmed, Stephen J Fowler, Tamara M E Nijsen, Royston Goodacre, Weda Hans, Hugo Knobel, Oluwasola Lawal, Iain R White, 2018, izvirni znanstveni članek

Opis: Introduction: Infections such as ventilator-associated pneumonia (VAP) can be caused by one or more pathogens. Current methods for identifying these pathogenic microbes often require invasive sampling, and can be time consuming, due to the requirement for prolonged cultural enrichment along with selective and differential plating steps. This results in delays in diagnosis which in such critically ill patients can have potentially life-threatening consequences. Therefore, a non-invasive and timely diagnostic method is required. Detection of microbial volatile organic compounds (VOCs) in exhaled breath is proposed as an alternative method for identifying these pathogens and may distinguish between mono- and poly-microbial infections. Objectives: To investigate volatile metabolites that discriminate between bacterial mono- and co-cultures. Methods: VAP-associated pathogens Enterobacter cloacae and Pseudomonas aeruginosa were cultured individually and together in artificial sputum medium for 24 h and their headspace was analysed for potential discriminatory VOCs by thermal desorption gas chromatography–mass spectrometry. Results: Of the 70 VOCs putatively identified, 23 were found to significantly increase during bacterial culture (i.e. likely to be released during metabolism) and 13 decreased (i.e. likely consumed during metabolism). The other VOCs showed no transformation (similar concentrations observed as in the medium). Bacteria-specific VOCs including 2-methyl-1-propanol, 2-phenylethanol, and 3-methyl-1-butanol were observed in the headspace of axenic cultures of E. cloacae, and methyl 2-ethylhexanoate in the headspace of P. aeruginosa cultures which is novel to this investigation. Previously reported VOCs 1-undecene and pyrrole were also detected. The metabolites 2-methylbutyl acetate and methyl 2-methylbutyrate, which are reported to exhibit antimicrobial activity, were elevated in co-culture only. Conclusion: The observed VOCs were able to differentiate axenic and co-cultures. Validation of these markers in exhaled breath specimens could prove useful for timely pathogen identification and infection type diagnosis.
Najdeno v: ključnih besedah
Povzetek najdenega: ...potential discriminatory VOCs by thermal desorption gas chromatography– mass spectrometry. Results: Of the 70 VOCs putatively...
Ključne besede: Bacteria, Enterobacter cloacae, Gas Chromatography-Mass Spectrometry, Infection, Pseudomonas aeruginosa, Volatile organic compounds
Objavljeno: 18.07.2019; Ogledov: 1415; Prenosov: 60
.pdf Polno besedilo (1,29 MB)

8.
Capturing and Storing Exhaled Breath for Offline Analysis
Stephen J Fowler, Iain R White, 2019, samostojni znanstveni sestavek ali poglavje v monografski publikaciji

Opis: In this chapter we will summarize and discuss methods for the capture and storage of exhaled breath, prior to offline (and indirect online) analysis. We will detail and compare methods currently in use, including their applications, key strengths, and limitations. In synthesizing the best features of each technique, we will propose an ideal standardized breath sampling solution, and give a personal vision on the next steps to be taken in this exciting area of breath research.
Najdeno v: ključnih besedah
Povzetek najdenega: ...Breath sampling, Offline analysis, Thermal desorption, Gas chromatography- mass spectrometry...
Ključne besede: Breath analysis, Breath sampling, Offline analysis, Thermal desorption, Gas chromatography-mass spectrometry
Objavljeno: 22.07.2019; Ogledov: 1615; Prenosov: 0
.pdf Polno besedilo (36,24 MB)

9.
Hypoxia influences the cellular cross-talk of human dermal fibroblasts. A proteomic approach.
Naldini Antonella, Tiozzo Roberta, Sommer Pascal, Carraro Fabio, Annovi Giulia, Boraldi Federica, Quaglino Daniela, 2007, izvirni znanstveni članek

Opis: The ability of cells to respond to changes in oxygen availability is critical for many physiological and pathological processes (i.e. development, aging, wound healing, hypertension, cancer). Changes in the protein profile of normal human dermal fibroblasts were investigated in vitro after 96 h in 5% CO2 and 21% O2 (pO2=140 mm Hg) or 2% O2 (pO2=14 mm Hg), these parameters representing a mild chronic hypoxic exposure which fibroblasts may undergo in vivo. The proliferation rate and the protein content were not significantly modified by hypoxia, whereas proteome analysis demonstrated changes in the expression of 56 proteins. Protein identification was performed by mass spectrometry. Data demonstrate that human fibroblasts respond to mild hypoxia increasing the expression of hypoxia inducible factor (HIF1a) and of the 150-kDa oxygen-regulated protein. Other differentially expressed proteins appeared to be related to stress response, transcriptional control, metabolism, cytoskeleton, matrix remodelling and angiogenesis. Furthermore, some of them, like galectin 1, 40S ribosomal protein SA, N-myc-downstream regulated gene-1 protein, that have been described in the literature as possible cancer markers, significantly changed their expression also in normal hypoxic fibroblasts. Interestingly, a bovine fetuin was also identified that appeared significantly less internalised by hypoxic fibroblasts. In conclusion, results indicate that human dermal fibroblasts respond to an in vitro mild chronic hypoxic exposure by modifying a number of multifunctional proteins. Furthermore, data highlight the importance of stromal cells in modulating the intercellular cross-talk occurring in physiological and in pathologic conditions.
Najdeno v: ključnih besedah
Povzetek najdenega: ...56 proteins. Protein identification was performed by mass spectrometry. Data demonstrate that human fibroblasts respond to...
Ključne besede: Human fibroblast, Primary cell culture, Hypoxia, Connective tissue, Proteome, 2D gel electrophoresis, Mass-spectrometry
Objavljeno: 22.07.2019; Ogledov: 1617; Prenosov: 0
.pdf Polno besedilo (919,07 KB)

10.
Uranium bearing dissolved organic matter in the porewaters of uranium contaminated lake sediments
Breda Novotnik, Wei Chen, R. Douglas Evans, 2018, izvirni znanstveni članek

Opis: Uranium (U) mobility in the environment strongly depends on its oxidation state and the presence of complexing agents such as inorganic carbon, phosphates, and dissolved organic matter (DOM). Despite the importance of DOM in U mobility, the exact mechanism is still poorly understood. Therefore, the aim of our investigation was to characterise sediment porewater DOM in two lakes in Ontario, Canada (Bow and Bentley Lakes) that were historically contaminated with U and propose possible composition of UO2-bearing DOM. Depth profiles of U concentrations in porewaters and total sediment digests reveal U levels of up to 1.3 mg L−1 in porewater and up to 0.8 mg−1 g in sediment. Depth profiles of U did not correlate with Fe, Mn, SO4 2−, or Eh profiles. Therefore, porewater DOM was analysed and taken into consideration as the primary source of U mobility. Porewater DOM in each sediment section (1 cm sections, 20 cm core length) was analysed by high-resolution electrospray ionisation mass spectrometry. PCA analyses of porewater DOM mass spectra showed grouping and clear separation of DOM in sediment sections with elevated U concentrations in comparison to sections with background U concentrations. Several criteria were set to characterise UO2-bearing DOM and more than 70 different molecules were found. The vast majority of these UO2-DOM compounds fell in the category of carboxyl-containing aliphatic molecules (H/C between 0.85 and 1.2 and O/C≤0.4) and had a mean value of m/z about 720.
Najdeno v: ključnih besedah
Povzetek najdenega: ...core length) was analysed by high-resolution electrospray ionisation mass spectrometry. PCA analyses of porewater DOM mass...
Ključne besede: Uranium Lake sediments Porewater Disolved organic matter High resolution mass spectrometry
Objavljeno: 09.10.2019; Ogledov: 1477; Prenosov: 0
.pdf Polno besedilo (1,48 MB)

Iskanje izvedeno v 0 sek.
Na vrh