• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 101
  • 87
  • 29
  • 10
  • 9
  • 9
  • 9
  • 7
  • 4
  • 3
  • 2
  • 2
  • Tagged with
  • 312
  • 312
  • 35
  • 35
  • 31
  • 28
  • 27
  • 27
  • 26
  • 26
  • 26
  • 25
  • 24
  • 24
  • 20
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
281

Physico-chimie des lipopolysaccharides et réponse inflammatoire : rôle des lipoprotéines / Physico-chemistry of lipopolysaccharides and inflammatory response : role of lipoproteins

Sali, Wahib 16 December 2014 (has links)
Le LPS est un puissant agent pro-inflammatoire bactérien, dont la partie lipide A est considérée comme le principe actif. Néanmoins, la chaîne O des LPS influence leur agrégation en solution aqueuse. Notre but a été de déterminer le rôle de la chaîne O sur les effets biologiques et physiopathologiques des LPS.Nos travaux, menés selon trois axes stratégiques complémentaires, ont donné lieu aux avancées suivantes :- développement d'un dosage innovant des LPS par LC-MS/MS et d'un ratio d'inactivation des LPS sur la base d'une utilisation combinée dudit dosage et du test LAL. Ce ratio traduit la capacité d'un organisme hôte à inactiver les LPS, notamment par leur transfert aux HDL par la PLTP. Ce ratio pourrait être utile dans l'évaluation des patients à haut risque.- la longueur de la chaîne O module l'inflammation induite par les LPS. Au-delà de leur concentration d'agrégation critique, les LPS forment des agrégats dotés d’une architecture et de propriétés physico-chimiques dépendant de leur chaîne O. Ces deux paramètres déterminent l'activité biologique des LPS et leur métabolisme ;- développement d'un double marquage innovant des LPS confirmant leur voie principale d'élimination : le transport inverse du LPS. Ce travail définit donc les effets physiopathologiques induits par les LPS comme résultant de deux composantes : leur activité biologique et leur métabolisme. Toute stratégie de recherche ou thérapeutique ciblant les LPS, devrait donc prendre en compte leur structure moléculaire, leur agrégabilité et la relation entre ces deux paramètres, déterminants majeurs de l'activité biologique des LPS et de leur métabolisme. / LPS is a potent bacterial pro-inflammatory agent, consisting of hydrophilic, polysaccharide part and of a lipid A which is considered like active moiety. Nevertheless, the O chain of LPS influences their aggregation in aqueous media. Therefore, our goal has been to determine the role of O chain on the LPS biological and physiopathological effects. Our work was organized according to three main axes, and led to the following findings :- development of a new LPS assay by LC-MS/MS. The combination of this new technique with LAL test allowed us to calculate an inactivation ratio which reflects the ability of host organism to inactivate LPS, especially through their transfer to HDL by PLTP. The ratio could be useful in predicting outcome of high risk patients.- the length of O chain modulates LPS-induced inflammation. Above their critical aggregation concentration, LPS form aggregates with an architecture and physiochemical properties dependent on their O chain. Both parameters determine LPS biological activity and their metabolism.- development of an innovative dual labelling of LPS as a new tool to explore LPS elimination pathway : the reverse LPS transport. This work brings evidence that the physiopathological effects of LPS depend on two parameters : their biological activity and their metabolism. Any strategy of research or therapeutic targeting LPS should take into account their molecular structure, their aggregability and the relation between the both parameters, which are major determinants of their biological activity and their metabolism.
282

Hemijska, biohemijska i mikrobiološka karakterizacija Trifolium pratense L. / Chemical, biochemical and microbiological characterization of Trifolium pratense L.

Vlaisavljević Sanja 19 September 2014 (has links)
<p>Hemijska karakterizacija ekstrakata&nbsp; <em>T. pratense&nbsp;</em>L.&nbsp; određena je LC-MS-MS, a etarskih ulja GC-MS analizom, pri čemu je&nbsp; identifikovano vi&scaron;e&nbsp;bioaktivnih jedinjenja.&nbsp; Spektrofotometrijskim&nbsp;metodama ispitan je antioksidantni potencijal&nbsp;ekstrakata i etarskih ulja. Hepatoprotektivni&nbsp;efekat određen je&nbsp; na&nbsp; homogenatu i hemolizatu&nbsp;jetre laboratorijskih mi&scaron;eva.&nbsp; Budući da&nbsp; ova&nbsp;biljka ima visok sadržaj izoflavona, određena je&nbsp;<br />estrogena, antiestrogena aktivnost, kao i&nbsp;citotoksičnost ekstrakata. Antimikrobna&nbsp;<br />aktivnosta ekstrakata i etarskih ulja ispitana je&nbsp;na&nbsp; &scaron;est bakterijskih sojeva.&nbsp; Ekstrakti i etarska&nbsp;ulja su bili umereno aktivni u pogledu biolo&scaron;kih&nbsp;aktivnosti, osim u slučaju antimikrobne&nbsp;aktivnosti koju nije pokazao nijedan ispitivani&nbsp;uzorak.</p> / <p>The chemical characterization of&nbsp; <em>T.&nbsp; pratense</em> extracts was determined by LC-MS-MS, and the essential oils of the GC-MS analysis, wherein the&nbsp; various&nbsp; bioactive compounds were identified.&nbsp; Antioxidant potential of extracts and essential oils was tested&nbsp; by spectrophotometric methods.&nbsp; Hepatoprotective&nbsp; effect&nbsp; was determined&nbsp; in&nbsp; haemolysate and liver homogenate of&nbsp; laboratory&nbsp; mice.&nbsp; Estrogen, antiestrogen activity, as well&nbsp; as the cytotoxicity of the extracts were&nbsp; determined&nbsp; due to the high&nbsp;content of isoflavones.&nbsp; Antimicrobial activity of extracts and essential oils was&nbsp; investigatied&nbsp; on six bacterial strains. Essential oils and extracts were moderately active in terms of biological activity, except&nbsp; in the case of&nbsp;&nbsp; antimicrobial activity&nbsp; where none of the extracts were active against tested bacterial strains.</p>
283

Entwicklung einer Multimethode zur Probenaufarbeitung und Bestimmung von gas- und flüssigkeitschromatographisch erfassbaren Pestiziden in Hühnereiern

Hildmann, Fanny 24 August 2016 (has links)
Die Rückstandsanalytik tierischer Lebensmittel ist eine anspruchsvolle Aufgabe aufgrund des hohen Lipidanteils der Proben sowie des sich stetig vergrößernden Wirkstoffspektrums. Heutzutage werden für die Probenaufarbeitung die DFG S 19 Methode, mit der vorrangig unpolare Analyten nachgewiesen werden und zunehmend die QuEChERS Methode eingesetzt, die insbesondere auf die Erfassung polarer Pestizide abzielt. In dieser Arbeit wurde eine moderne Multirückstandsmethode für Hühnereier entwickelt, um sowohl gas- als auch flüssigkeitschromatographisch (GC, LC) erfassbare Wirkstoffe zu analysieren. Dazu gehören unpolare PCBs, Pyrethroide und Organochlorpestizide, aber auch polarere Organophosphate, Triazole und Carbamate. Das Verfahren basiert auf der Extraktion mittels Matrix Solid Phase Dispersion, der Reinigung auf Grundlage einer modifizierten Gelpermeationschromatographie (GPC) und zwei verschiedenen Festphasenextraktionen (SPEs) für GC- und LC-erfassbare Pestizide sowie der Quantifizierung mittels GC- und LC-MS/MS. Dünnschichtchromatographisch wurde die effektive Entfernung hochmolekularer Lipide durch die modifizierte GPC und niedrigmolekularer Fette durch die SPEs belegt. Laut der für Ei durchgeführten Validierung erfüllten 164 der 172 untersuchten Pestizide und alle sechs PCBs die Leistungskriterien für die amtliche Rückstandskontrolle - zumeist am niedrigsten validierten Level (5 µg/kg bzw. 0,5 µg/kg). Ausnahmen bildeten sehr polare LC-Pestizide (z.B. Aminopyralid, Clopyralid, MCPA, Quinmerac) und pH-Wert-abhängige GC-Analyten (Nicotin, Tolylfluanid, Dichlofluanid), die auch mit den etablierten Verfahren schwierig zu analysieren sind. Weiterhin verdeutlichte die erfolgreiche Untersuchung von verschiedenen Ringversuchsmaterialien, dass die ursprünglich für Eier entwickelte Methode auch für mageres Geflügelfleisch und Sahne genutzt werden kann. Gegenüber den etablierten Verfahren wies die neue Methode deutliche Vorzüge auf. So belegte die Dünnschichtchromatographie, dass mit der neuen Methode Cholesterin, aber auch freie Fettsäuren besser abgetrennt werden als mit den etablierten Verfahren. Die neue Methode verbrauchte im Vergleich zur DFG S 19 Methode 46 % weniger Lösungsmittel und ermöglichte eine Verdopplung des Probendurchsatzes innerhalb von 8 h. Zudem eignete sich das entwickelte Verfahren laut den Validierungsdaten für GC-Analyten deutlich besser als die QuEChERS Methode und etwas besser als die DFG S 19 Methode (v.a. für Pyrethroide). Hinsichtlich der LC-Analyten unterschieden sich die neue und die QuEChERS Methode nur bei wenigen Analyten. Mit dem neuen Verfahren konnten folglich im Gegensatz zu den etablierten Methoden sowohl unpolare GC- als auch polare LC-Analyten sicher erfasst werden.:1 EINLEITUNG UND ZIELSTELLUNG 1 2 THEORETISCHE GRUNDLAGEN 3 2.1 Grundlagen der Pestizidanalytik 3 2.1.1 Definitionen 3 2.1.2 Rechtliche Grundlagen in Bezug auf tierische Lebensmittel 3 2.2 Herausforderung der Analytik tierischer Lebensmittel 6 2.2.1 Erfassen eines breiten Analytspektrums 6 2.2.2 Komplexität der tierischen Matrix 8 2.3 Probenaufarbeitung tierischer Lebensmittel 11 2.3.1 Extraktion 11 2.3.2 Möglichkeiten der Lipid-Reinigung 14 2.3.3 Messmethoden in der modernen Pestizidanalytik 18 2.4 Multimethoden in der Pestizidanalytik tierischer Lebensmittel 21 2.4.1 Vorstellung etablierter Multimethoden 21 2.4.2 Vergleich etablierter Multimethoden 24 2.4.3 Forschungsergebnisse bezüglich fetthaltiger Matrizes bis 2010 26 3 ERGEBNISSE 28 3.1 Auswahl relevanter Analyten in tierischen Lebensmitteln 28 3.2 Auswahl der Matrix Hühnerfrischei 30 3.3 Messung mittels GC-MS/MS und LC-MS/MS 32 3.3.1 Ansatz 32 3.3.2 Erstellung einer GC-MS/MS Datenbank 33 3.3.3 Besonderheiten der SRM-Messmethoden 36 3.3.4 Vorsäulen-Backflush in der Gaschromatographie 38 3.3.5 Leistungsfähigkeit der SRM-Methoden 44 3.4 Beurteilung des Reinigungseffektes 45 3.5 Entwicklung der Probenaufarbeitungsmethode 47 3.5.1 Ziele und allgemeines Vorgehen 47 3.5.2 Extraktion mittels Matrix Solid Phase Dispersion 48 3.5.3 Konzentrierung von Lösungsmittelextrakten 55 3.5.4 Lipidentfernung durch Ausfrieren 56 3.5.5 Modifizierung der GPC zur Verbesserung der Wirtschaftlichkeit 57 3.5.6 Festphasenextraktion 63 3.6 Analysemethode für Eier 78 3.7 Validierung der neuen Analysemethode 82 3.7.1 Hintergrund und Durchführung 82 3.7.2 Linearität 83 3.7.3 Spezifität 84 3.7.4 Wiederfindungsraten und Wiederholbarkeit 84 3.7.5 Bestimmungsgrenze 88 3.7.6 Matrix-spezifische Auswirkung auf die Analyten 88 3.8 Vergleich mit etablierten Probenaufarbeitungsmethoden 89 3.8.1 Ansatz 89 3.8.2 Reinigungseffekt 90 3.8.3 Validierungsdaten 93 3.8.4 Identifizierung und Quantifizierung anhand gewachsener Rückstände 95 3.8.5 Zusammenfassende Bewertung 97 3.9 Untersuchung verschiedener Ringversuchsmaterialien 99 4 DISKUSSION 103 4.1 Entwickelte Analysemethode 103 4.2 Ausblick 111 5 ZUSAMMENFASSUNG 113 6 LITERATUR 117 7 ANHANG A-1
284

Multiple-approaches to the identification and quantification of cytochromes P450 in human liver tissue by mass spectrometry

Seibert, C., Davidson, B.R., Fuller, B.J., Patterson, Laurence H., Griffiths, W.J., Wang, Y. January 2009 (has links)
No / Here we report the identification and approximate quantification of cytochrome P450 (CYP) proteins in human liver microsomes as determined by nano-LC-MS/MS with application of the exponentially modified protein abundance index (emPAI) algorithm during database searching. Protocols based on 1D-gel protein separation and 2D-LC peptide separation gave comparable results. In total, 18 CYP isoforms were unambiguously identified based on unique peptide matches. Further, we have determined the absolute quantity of two CYP enzymes (2E1 and 1A2) in human liver microsomes using stable-isotope dilution mass spectrometry, where microsomal proteins were separated by 1D-gel electrophoresis, digested with trypsin in the presence of either a CYP2E1- or 1A2-specific stable-isotope labeled tryptic peptide and analyzed by LC-MS/MS. Using multiple reaction monitoring (MRM) for the isotope-labeled tryptic peptides and their natural unlabeled analogues quantification could be performed over the range of 0.1-1.5 pmol on column. Liver microsomes from four individuals were analyzed for CYP2E1 giving values of 88-200 pmol/mg microsomal protein. The CYP1A2 content of microsomes from a further three individuals ranged from 165 to 263 pmol/mg microsomal protein. Although, in this proof-of-concept study for CYP quantification, the two CYP isoforms were quantified from different samples, there are no practical reasons to prevent multiplexing the method to allow the quantification of multiple CYP isoforms in a single sample.
285

Development and validation of a LC-MS/MS method for analysis of perfluorooctanesulfonic acid and perfluorooctaonic acid in liver organoid media

Heggebø Rolfsen, Sandra January 2024 (has links)
Per- and polyfluoroalkyl substances (PFAS) are organic synthetic compounds used in several industries because of their unique properties and thermal and chemical stability. Perfluorooctanesulfonic acid (PFOS) and perfluorooctaonic acid (PFOA) are two of the most prominent PFAS that are undegradable and accumulate in nature. To study the impact of PFOS and PFOA on the liver in a controlled environment, organoids can be used. A sensitive and selective LC-MS/MS method for individual and simultaneous analysis of PFOS and PFOA in liver organoid media and equipment used in organoid analyses was developed. For detection of low concentrations, ability to analyse complex organoid samples, and limit background contamination, a solid phase extraction (SPE) column, automatic filter (AFFL) and a trap column was included. The AFFL-SPE-LC-MS/MS was optimised efficiently through Design of Experiment (DoE) regarding the loading phase in the LC and six MS parameters for PFOS and PFOA. Validation was controlled against Eurachem’s guideline showing high sensitivity, detecting LOD at 6 pg/mL. The method demonstrated high repeatability with an RSD below 8 % for most samples. Simultaneous analysis of PFOS and PFOA demonstrated high selectivity. Nevertheless, the method showed low intermediate precision and varying reliability, as well as persistent background contamination limiting detection of lower concentrations. The method was fit for purpose and allowed rapid analysis of PFOS and PFOA in organoid media and equipment used in organoid analyses. Result from studies of PFAS in liver organoids through analysis with this method can aid in understanding the connection between PFAS and metabolic diseases. / Populärvetenskaplig sammanfattning Per- och polyfluorerade alkylsubstanser (PFAS) är en grupp av människoskapta, syntetiska ämnen med unika egenskaper. Dessa egenskaper gör att de är olja- och vattenavvisande, och har många applikationsområden. De finns i textiler, livsmedelsförpackningar, brandsläckningsskum och andra industriprodukter. De är väldigt termiskt och kemisk stabila, vilket gör att de inte bryts ner och därmed ackumulerar i miljön. Flera studier har också visat koppling mellan PFAS och många kroniska sjukdomar, som hormonstörningar, cancer, immunsuppression och metabolt associerad fettlever (MAFLD, tidigare nonalkoholisk fettlever (NAFLD)). Kopplingen mellan MAFLD och PFAS har fått mycket uppmärksamhet då levern har visats sig vara ett målorgan för PFAS. Eftersom PFAS är ihärdiga, har ett komplicerat spridningsbeteende och ackumulerar i naturen är det svårt att studera kopplingen mellan MAFLD och PFAS i en kontrollerad miljö. För att studera effekten av PFAS kan man använda organoider, laboratorieodlade 3D modeller gjord från stamceller för att imitera ett äkta organ.    Någon av de mest omtalade PFAS ämnen är perfluoroktansyra (PFOA) och perfluoroktansulfonat (PFOS), vilket är fokus för detta arbete. Leverorganoiderna kan utsättas för PFOS och PFOA, och mediet de ligger i kan extraheras och studeras med konventionella analytiska metoder för att få en bild av hur PFAS påverkar levern. I detta arbete vill analysen ske via vätskekromatografi med masspektrometri som detektion (LC-MS/MS). Med LC-MS/MS separeras den studerade molekylen, analyten från lösningen baserat på dess kemiska egenskaper. Analyten detekteras baserat på dess massa, mer bestämd massa/laddning-fördelningen (m/z). För att anpassa LC-MS metoden till injektion av komplexa organoidprover inkluderades ett automatiskt filter (AFFL) samt ett extra automatiskt separationssteg med en kolonn med fastfasextraktion (SPE). I övrigt ger SPE möjligheten att små mängder PFAS kan uppkoncentreras och fokuseras på kolonnen, vilket ger en sensitiv metod som kan detektera låga koncentrationer. SPE och AFFL implementerades båda för att bättre kunna separera och detektera PFOS och PFOA från andra ämnen, samt filtrera bort föroreningar och stora molekyler som kan skada LC-MS/MS instrumentet i längden. Då PFAS hopar upp sig i vår omgivning, visade det sig att kontamination av PFAS från systemet blev en utmaning under metodutvecklingen. Därför implementerades PFAS fritt utstyr, samt en extra kolonn för att fånga PFAS från systemet och på så sätt minska bakgrundskontaminationen som detekterades.    AFFL-SPE-LC-MS/MS metoden optimerades via en maskininlärningsbaserad optimeringsmetod baserad på parametrar i LC och MS. Metoden baserar sig på att, med tre värden för varje parameter, uppger programmet ett antal experiment som måste utföras för att kunna beräkna ett optimalt värde för varje parameter. Med resultatet från experimenten kan modellen matematiskt, genom en Bayes baserat Gaussian modell, uppskatta optimala värden för metoden. På så sätt kunde metoden optimeras systematiskt och tidseffektivt.    Innan rutinanvändning måste den optimerade metoden valideras. Validering blev gjord genom at följa Eurachem’s riktlinjer. Metoden visade hög repeterbarhet, selektivitet och riktighet. Den har hög sensitivitet, och kan detektera låga mängder, men bakgrundskontaminationen kunde inte elimineras totalt, och gör att man måste korrigera för detta i rutinanalyser. Komplexiteten av AFFL-SPE-LC-MS/MS med flera kolonner och filter gjorde att metoden visade låg robusthet och behövde justeras ofta. AFFL-SPE-LC-MS/MS metoden gör det möjligt att snabbt studera PFOS och PFOA i leverorganoider och utstyr använt i organoidanalyser, och kan bidra i forskningen för att bättre förstå hur PFAS påverkar levern. / Health Effects of Persistent Organic Pollutants
286

Synthesis of nordihydroguaiaretic acid (NDGA) analogues and their oxidative metabolism

2015 June 1900 (has links)
Nordihydroguaiaretic acid (NDGA), is a naturally-occurring lignan isolated from the creosote bush (Larrea tridentata). The aqueous extract of this shrub, commonly referred to as Chaparral tea, was listed in the American pharmacopeia as an ethnobotanical used to treat tuberculosis, arthritis and cancer. Other documented traditional applications of creosote bush extract include treatment for infertility, rheumatism, arthritis, diabetes, gallbladder and kidney stones, pain and inflammation among many others. In spite of the numerous pharmacological properties, NDGA use has been associated with toxicities including hepatotoxicity in humans. Previous studies in our group showed that oxidative cyclization of NDGA (a di-catechol) at physiological pH forms a dibenzocyclooctadiene that may have therapeutic benefits whilst oxidation to ortho-quinone likely mediates toxicological properties. In order to investigate the structural features responsible for pharmacological and toxicological properties, a series of NDGA analogues were designed, synthesized and characterized for the purpose of studying their oxidative metabolism. Literature procedures were modified to successfully prepare seven lignan analogues via multi-step synthesis. In our effort to understand the mechanisms of NDGA intramolecular cyclization, the prepared analogues were incubated under previously established conditions where NDGA autoxidized to yield the dibenzocyclooctadiene derivative. We also evaluated the stability of the analogues under the conditions of this study. Furthermore, we evaluated bioactivation potential of the prepared analogues with a goal of eliminating reactive metabolite liability through rational structural modification. We incubated NDGA and its analogues in rat liver microsomes (RLM) in the presence of glutathione as a nucleophilic trapping agent. Standards for comparison were generated by performing glutathione trapping experiments with chemical and enzyme oxidation systems. The potential of the dibenzocyclooctadiene lignan 2 derived from NDGA under physiological conditions to contribute to toxicological properties via reactive metabolite formation was also evaluated. Glutathione conjugates were detected by electrospray ionization-mass spectrometry (ESI-MS) scanning for neutral loss (NL) 129 Da or 307 Da in positive ion mode or precursor ion (PI) scanning for 272 Da in negative ion mode and further characterized by liquid chromatography–tandem mass spectrometry (LC–MS/MS) or in a single LC-MS run using multiple reactions monitoring (MRM) as a survey scan to trigger acquisition of enhanced product ion (EPI) data. We determined that NDGA autoxidation at pH 7.4 is dependent on substituents and/or substitution pattern on the two aromatic rings. In particular, spontaneous intramolecular cyclization to a dibenzocyclooctadiene required a di-catechol lignan, raising the possibility that o-Q formation may not be necessary for cyclization to occur. Cyclization was significantly inhibited in the presence of excess GSH which supports the involvement of free radicals as opposed to o-Q in the intramolecular cyclization process. The mono-catechol analogues A1 and A4 underwent oxidation to o-Q but no evidence of cyclization was found implying that electrophilic substitution cannot account for NDGA cyclization. The phenol-type analogues were oxidatively more stable in comparison with the catechol-type analogues at pH 7.4. The results demonstrate that electrophilic substitution makes no contribution to the intramolecular cyclization process and that a radical mediated process accurately describes the situation for NDGA. Oxidative metabolism and bioactivation studies on NDGA and its analogues revealed that reactive metabolites formation is dependent on substitution and/or substitution pattern of the aromatic rings. Cytochrome P450-mediated oxidation of NDGA and its catechol-type analogues yielded electrophilic intermediates which reacted with GSH. The GSH mono-conjugates were identified as ring adducts derived from o-Q although the position at which the GSH binds to the aromatic rings could not be determined. We also found that NL 129 or 307 scanning in positive ionization mode has potential diagnostic utility in distinguishing between aromatic and benzylic GSH conjugates although further studies may be required for validation. We found no evidence of p-QM either directly or via isomerization of o-Q intermediates suggesting that o-Q is the major reactive toxicophore responsible for reactive metabolite mediated toxicities associated with NDGA use. In addition, we demonstrated that the NDGA-derived dibenzycyclooctadiene lignan (cNDGA 2) undergoes P450-mediated oxidation to a reactive metabolite which might have toxicological implications. There was no evidence of P450-mediated oxidation to reactive metabolites for the phenol-type NDGA analogues. It is concluded that structural modification efforts should focus on phenol-type analogues to potentially enhance the safety profile of NDGA.
287

IDENTIFICATION OF CLINICAL, LABORATORY AND GENETIC COVARIATES FOR PHARMACOKINETICS, EFFICACY AND TOXICITY OF SORAFENIB IN PATIENTS WITH SOLID TUMORS

JAIN, LOKESH 10 August 2009 (has links)
The goal of this research work was to understand the clinical-pharmacology based treatment approaches for sorafenib. Treatment with sorafenib is associated with high inter-patient variability in pharmacokinetic exposures, efficacy and toxicity. We explored the demographic, laboratory, clinical and pharmacogenetic factors to elucidate the sources of variability. In addition, we examined the impact of pharmacogenetic variation in VEGFR2, an important mediator of the VEGF pathway, on risk of prostate cancer. To support these investigations, (mainly single-dose) pharmacokinetic, pharmacogenetic, efficacy and toxicity information were collected from patients with solid tumors, enrolled in five phase I / II clinical trials at National Cancer Institute. Non-compartmental analysis-general linear modeling (NCA-GLM), population pharmacokinetic analysis and several correlative studies were performed to characterize the sources of variability in pharmacokinetics and response. The role of prostate specific antigen (PSA) and ex-vivo anti-angiogenic activity as efficacy markers was evaluated, respectively, for patients with prostate cancer treated with sorafenib and patients with solid tumors treated with combination of sorafenib and bevacizumab. Sweat concentrations of sorafenib were measured to study its association with development of hand-foot skin reaction (HFSR). Only body weight was a significant covariate for volume of distribution by population pharmacokinetic analysis, while BSA, albumin and UGT1A9*3 appeared to be significant by NCA-GLM. However, the contribution of these covariates in overall exposure variability was very small; hence, these were considered clinically irrelevant. The association of sorafenib exposure with efficacy in patients with prostate cancer, colorectal cancer and combined solid tumors were not significant; exposure-efficacy relationship for lung cancer patients requires further evaluation. Sorafenib exposures appeared to be associated with incidences of rash in single agent trials and with HFSR in trials involving treatment with sorafenib and bevacizumab combination. In-vitro cell-line experiments determined that prostate specific antigen (PSA) is not a suitable marker of efficacy in patients with prostate cancer treated with sorafenib. The ex-vivo anti-angiogenic activity, measured by rat-aortic ring assay using patient serum samples, appeared to be not associated with clinical response. Sorafenib concentration in sweat, upto ≥5 ng/mL, apparently was not associated with HFSR. The VEGFR2 H472Q polymorphism was associated with progression-free survival (PFS) (with an apparent heterozygous advantage for survival) and toxicities in patients treated with drugs against the VEGF pathway. Patients who developed hypertension and HFSR on bevacizumab and sorafenib therapy, respectively, appeared to have longer PFS. Therefore, these side effects should be effectively managed to avoid/delay the treatment discontinuation. The VEGFR2 H472Q and V297I genotype were not predictive of risk of prostate cancer in Caucasian subjects.
288

Quantitative Analysis of Tobacco Specific Nitrosamine in Human Urine Using Molecularly Imprinted Polymers as a Potential Tool for Cancer Risk Assessment

Shah, Kumar 18 November 2009 (has links)
Measuring urinary tobacco specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronide conjugate may provide the best biomarker of tobacco smoke lung carcinogen metabolism. Existence of differences in the extent of NNAL metabolism rates may be potentially related to an individuals’ lung cancer susceptibility. Low concentrations of NNAL in smokers urine (<1 ng/mL) require sensitive and selective methods for analysis. Traditionally, this involves extensive, time-consuming sample preparation that limits throughput and adds to measurement variability. Molecularly imprinted polymers (MIPs) have been developed for the analysis of urinary NNAL by offline cartridge extraction combined with LC-MS/MS. This method when reproduced demonstrated problems with matrix effects. In the first part of this work, investigation of matrix effects and related problems with sensitivity for the published offline extraction method has been conducted. In order to address the need to improve throughput and other analytical figures of merit for the original method, the second part of this work deals with development of a high-throughput online microfluidic method using capillary-columns packed with MIP beads for the analysis of urinary NNAL. The method was validated as per the FDA guidance, and enabled low volume, rapid analysis of urinary NNAL by direct injection on a microfluidic column packed with NNAL specific MIP beads. The method was used for analysis of urinary NNAL and NNAL-Gluc in smokers. Chemometric methods were used with this data to develop a potential cancer-risk-assessment tool based on pattern recognition in the concentrations of these compounds in urine. In the last part, method comparison approaches for the online and the offline sample extraction techniques were investigated. A ‘fixed’ range acceptance criterion based on combined considerations of method precision and accuracy, and the FDA bioanalytical guidance limits on precision and accuracy was proposed. Data simulations studies to evaluate the probabilities of successful transfers using the proposed criteria were performed. Various experimental designs were evaluated and a design comprised of 3 runs with 3 replicates each with an acceptance range of ±20% was found appropriate. The off-line and the on-line sample extraction methods for NNAL analysis were found comparable using the proposed fixed range acceptance criteria.
289

Análise de canabinóides e cocaínicos em amostras de cabelo e sua correlação com sintomas psiquiátricos / Analysis of cannabinoids and cocainics in hair samples and correlation with psychiatric symptoms

Alves, Marcela Nogueira Rabelo 08 July 2015 (has links)
O consumo dos diferentes tipos de drogas está associado a problemas sociais, econômicos e de saúde pública, em todas as regiões no mundo. Dentre os problemas de saúde pública, podemos destacar a alta prevalência de comorbidade entre o uso de drogas e os transtornos mentais. A Cannabis, a cocaína e o crack são as drogas ilícitas mais consumidas no Brasil. A utilização do cabelo como matriz biológica para determinação destas drogas permite avaliar o uso crônicos pelos indivíduos, uma vez que o cabelo é uma matriz estável, de fácil manipulação e a janela de detecção depende apenas do comprimento do cabelo. Entretanto, a análise em cabelo ainda representa um desafio analítico. Foram desenvolvidos dois métodos para a detecção das diferentes drogas no cabelo, com diferentes enfoques analíticos. O primeiro método (desenvolvido durante o estágio de doutorado sanduíche na Itália) identificou e quantificou cocaína e metabólitos usando a técnica de column switching e detecção por LC-MS/MS. O segundo método foi desenvolvido para determinação de canabinóides nas amostras de cabelo utilizando GC-MS. O diferencial deste método foi a utilização de um novo dispositivo de extração em fase sólida (as ponteiras DPX) para concentração e purificação do extrato, utilizando menor quantidade de solventes. A determinação dos canabinóides e cocaínicos foi realizada nas amostras de cabelo da população atendida no CAPS - AD de Ribeirão Preto, São Paulo. Além da coleta da amostra de cabelo, o sujeito foi submetido a uma entrevista, onde os seguintes instrumentos de avaliação foram aplicadas: Questionário sobre a saúde do Paciente 9, Inventário de fobia social, Self Report Questionnaire, Questionário de Ansiedade de Beck, Inventário de Depressão de Beck e Questionário sobre o uso da Cannabis, bem como um questionário elaborado pelo pesquisador para coleta de dados sociodemográficos, consumo de substâncias e dados sobre a amostra de cabelo, como comprimento, cor, tintura ou coloração. As amostras de cabelo foram analisadas e a média das concentrações de cada droga encontrada no cabelo foi correlacionada com os indicadores clínicos de transtorno mentais, obtidos através dos instrumentos de avaliação psiquiátrica. A maior prevalência de indicadores clínicos positivos para transtornos psiquiátricos entre a população estudada foi de transtornos mentais comuns, entre eles a ansiedade e depressão. A comparação da média de concentração de Cannabis, cocaína e crack no cabelo com os indicadores clínicos positivos para os transtornos não apresentou resultados estatisticamente significantes. Entretanto, podemos inferir que os sujeitos que apresentaram maior concentração média de Cannabis e cocaína no cabelo possuíam mais indicadores clínicos positivos para sintomas mentais comuns e depressão maior enquanto que os sujeitos usuários de crack possuíam mais indicadores clínicos positivos para sintomas ansiedade. Apesar de algumas limitações, podemos concluir que o estudo possibilitou estimar a prevalência da morbidade entre abuso de drogas ilícitas e transtornos psiquiátricos na população atendida no Centro de Atenção Psicossocial Álcool e drogas de Ribeirão Preto. / Different kinds of drug use have been associated to social, economic and health public problems worldwide. Among the high prevalent public health problems is the comorbidity between drug abuse and psychiatric disorders. Cannabis, cocaine and crack are the most consumed illicit drugs in Brazil. Hair use as the biological matrix for the determination of these drugs allows to evaluate chronic use, once hair is a stable matrix, easy to manipulate and the window detection only depends on the size of the hair. However, hair analysis still represents an analytical challenge. It was developed two methods for the detection of the drugs in hair, with different analytical approach. The first method (developed during doctoral stage in Italy) had identified and quantified cocaine and metabolites using column switching technique and LCMS/ MS detection. The second method was developed for determination of cannabinoids in hair samples using GC-MS. Decontamination procedure was the same cited above. The differential of this method was the use of a new device in solid phase extraction (DPX tips) for the extracts concentration and purification, using less solvents volumes. Cannabinoids and cocaine analysis were performed in hair samples from people who were enrolled in the CAPS - AD of Ribeirão Preto, São Paulo. Besides hair collection, the individual was submitted to an interview, where it was applied the following evaluation scales: Patient health questionnaire - 9, Social phobia inventory, Self report questionnaire, Beck anxiety inventory, Beck depression inventory and Cannabis research questionnaire as well as a questionnaire made by the author to collect sociodemographic data, substance consume and hair data. Hair samples were analyzed and the concentrations were correlated with positive clinical factors of mental disorders obtained through evaluation scales. The highest prevalence of positive clinical indicators for psychiatric disorders among the population studied was of common mental disorders, including anxiety and depression. The comparison of the average concentration of Cannabis, cocaine and crack in the hair with the positive clinical indicators for the disorders did not show statistically significant results. However, we can infer that the subjects who had higher average concentration of Cannabis and cocaine in hair had showed positive indicators for common mental symptoms and major depression as well as the subjects who had higher average concentration of crack in hair had showed positive indicators for anxiety. Despite of some limitations, we can conclude that the study had allowed estimating the prevalence of morbidity among illicit drugs abuse and psychiatric disorders in the population enrolled in the psychosocial care center in Ribeirão Preto.
290

Metaproteomic Investigation of the Vaginal Microbiome in Pregnancy

Hassan, Zaneera 01 January 2019 (has links)
The development of early diagnostics and prevention strategies for preterm birth is an important global health challenge with the potential to impact over 15 million children annually, by improving health outcomes and reducing economic burden. Advances in microbial sequencing technology have opened the door to 16S rRNA gene survey, whole metagenomics, and whole transcriptomics, providing molecular evidence that the composition of the vaginal microbiome affects pregnancy outcomes in women, particularly those of African descent. A current gap in our molecular level understanding of the vaginal microbiome as it relates to healthy pregnancies is the metaproteome which comprises proteins from both the woman and colonizing microorganisms. Herein, I describe the development of a label-free mass spectrometry-based workflow for preparing and analyzing the vaginal metaproteome as sampled from vaginal swab extracts. The workflow was applied to two longitudinal cohorts of vaginal swab samples collected during the VCU MOMS-PI study. The work presented herein demonstrates for the first time that sufficient vaginal-specific biomaterial can be extracted from swabs for metaproteomics analysis as evidenced by high proteome coverage (>1790 human and >1609 microbial proteins), quantitative readouts for over 37% of identified proteins, and the identification of candidate protein biomarkers that change with gestational age and parturition status.

Page generated in 0.0323 seconds