Orientador: Marta Cristina Teixeira Duarte / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-26T04:57:52Z (GMT). No. of bitstreams: 1 Matsumura_LauraYumeRodrigues_M.pdf: 1312693 bytes, checksum: 7afc440e71f8e63ffdb4e0f57d78115f (MD5) Previous issue date: 2014 / Resumo: As leveduras causam deterioração de uma grande variedade de produtos alimentícios e nas indústrias de bebidas, além de serem resistentes a muito conservantes químicos. Os óleos essenciais e extratos de plantas têm surgido como alternativas seguras para substituir conservantes sintéticos. Contudo, os mecanismos de ação de óleos essenciais sobre micro-organismos são complexos e não estão completamente elucidados. Neste trabalho, foi investigada a ação de 14 óleos essenciais e 2 extratos diclorometânicos provenientes de plantas medicinais e aromáticas pertencentes à CPMA (Coleção de Plantas Medicinais e Aromáticas) do CPQBA/UNICAMP sobre leveduras do gênero Candida e sobre Pichia guilliermondii de importância em alimentos. Foi determinada a concentração mínima inibitória (MIC) e os efeitos sobre a lise da membrana celular, sobre os carboidratos de reserva trealose e glicogênio, sobre a depleção de ATP e sobre a biossíntese de ergosterol. Os resultados demonstraram que o óleo essencial de Cinnamomum burmanni foi o que apresentou melhor potencial para controle das leveduras, sendo o cinamaldeído e o acetato de cinamila os compostos majoritários presentes neste óleo. A investigação dos possíveis mecanismos de ação do óleo essencial de C. burmanni sobre Candida albicans ATCC 10231 demonstrou que este afetou a viabilidade da levedura a partir da concentração de 0,5 mg/mL (5MIC), e ocasionou a lise da membrana celular, havendo liberação de proteínas e lipídios para o meio extracelular, além de depleção de ATP. No caso dos carboidratos de reserva, os resultados demonstraram que o óleo essencial de C. burmanni ocasionou acúmulo de trealose, possivelmente pelo estresse ocasionado às células. Nenhum efeito foi observado sobre a reserva de glicogênio e sobre a inibição da síntese de ergosterol. Os resultados indicam a ação inibitória do óleo essencial de C. burmanni e mostram que este apresenta potencial para controle de leveduras de importância em alimentos / Abstract: Yeasts cause deterioration of a wide variety of food and drink industries, besides being very resistant to chemical preservatives. Essential oils and plant extracts have emerged as safe alternatives to synthetic preservatives. However, the mechanisms of action of essential oils on microorganisms are complex and not fully elucidated. In this work, was investigated the action of 14 essential oils and 2 dichloromethane extracts from medicinal and aromatic plants belonging to the Collection of Medicinal and Aromatic Plants - CPMA at CPQBA/ UNICAMP on Candida species and Pichia guilliermondii of importance in foods. The minimum inhibitory concentration (MIC) was determined and the effects of the essential oil on the cell membrane lysis, the carbohydrate reserves trehalose and glycogen, depletion of ATP and ergosterol biosynthesis were evaluated. The results showed that the essential oil from Cinnamomum burmanni presented the best potential to control the Candida spp. being the cinnamaldehyde and cinnamyl acetate the major compounds present in this oil. The investigation of the possible mechanisms of action of the C. burmanni essential oil on Candida albicans ATCC 10231 showed that the oil affected the viability of the yeast from 0.5 mg/mL (5MIC), and caused lysis of the cell membrane, with release of proteins and lipids into the extracellular environment, as well as ATP depletion. In the case of carbohydrate reserves, the results showed that the essential oil of C. burmanni caused accumulation of trehalose, possibly due to the cellular stress. No effect was observed on the synthesis of glycogen and ergosterol. The results indicate the inhibitory action of the essential oil from C. burmanni and show its potential to control yeasts of importance in foods / Mestrado / Ciência de Alimentos / Mestra em Ciência de Alimentos

Orientador: Alberto Vazquez Saa / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-21T14:37:47Z (GMT). No. of bitstreams: 1 Siqueira_KellenManoela_M.pdf: 18530292 bytes, checksum: b14fcd17f860e0698970af4213e1e126 (MD5) Previous issue date: 2012 / Resumo: O ATP (adenosina tri-fosfato) é uma molécula chave para a fisiologia, atuando como fonte de energia para diversos processos celulares. ...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: ATP (adenosine triphosphate acts as an "energy currency" providing energy to several physiological processes. ...Note: The complete abstract is available with the full electronic document / Mestrado / Matematica Aplicada / Mestre em Matemática Aplicada

A synthetic pathway towards the cap-structure of 2,2,7-trimethylguanosine containing a methylene modified triphosphate bridge have been investigated. The modification to the triphosphate bridge is hoped to slow down cap degradation and give the connected  oligunucleotide an increased lifetime. This could result in an better understanding of nuclear transport of oligonucleotides and could thereby helping to develop new treatments for different diseases. The synthesis relies on a coupling reaction between the 2,2,7-trimethylguanosine 5’phosphate and 2’-O-methyladenosine with a 5’-pyrophosphate where the central oxygen has been replaced by a methylene group. The reaction pathway consists of 9 steps of which 8 steps have been successfully performed. The last step, which includes a coupling reaction, was attempted but without successful identification and isolation of the cap-structure, and will need further attention. The reaction has been performed in a milligram scale with various yields. / Presentation utförd

Malaria, caused by an intracellular Plasmodium parasite, remains a devastating disease, having claimed approximately 655 000 lives worldwide in 2010. The Medicines for Malaria Venture suggests a "single-dose radical cure" as the ideal malaria treatment since rapid clearance of blood-stage parasites and symptom relief improves patient compliance and limits drug resistance. Thus, novel antimalarials should be rapid-acting and assessing their rate of activity is critical to drug discovery. Traditional evaluation of this rate by morphological assessments is flawed by highly subjective, operator-specific interpretations, mainly due to heterogeneous parasite morphology under routine culture conditions. This study aimed to develop an alternative, quantitative assay. Energy is vital for the growth and maintenance of all living organisms. Commercially available kits allow rapid quantification of the cell's energy currency, ATP. Therefore, quantification of parasite ATP shows potential for diagnosing abnormal parasite metabolism and the kinetics of drug action. In this study, a rapid protocol for detecting ATP in Plasmodium falciparum parasites using a luminescence-based kit was developed and optimised. Furthermore, luciferase-expressing transgenic parasites, in which luciferase activity is detected using a similar kit, were acquired. The utility of both methods for evaluating the rate of drug-induced stress was explored using antimalarials with varying modes of action and, presumably, rates of activity. Results showed that parasite ATP remained unchanged, increased or decreased during drug exposure. Morphological examinations by light microscopy and a Recovery assay, aided interpretation of the drug-induced changes in parasite ATP. These investigations suggested that unchanged parasite ATP levels reflect poor drug action, increased ATP levels indicate a stress response and partially compromised viability, while significantly reduced ATP reflects severely compromised viability. Concerning the Luciferase assay, parasite luciferase activity decreased during drug exposure, even in the presence of proteasome inhibitors. Changes in parasite ATP and luciferase activity occurred at rates which suggested that chloroquine is slow-acting, mefloquine has a moderate rate of activity and artemisinin is rapid-acting. These findings are compatible with the expected rates of activity of these established antimalarials. Hence, measurement of parasite ATP and/or luciferase activity may support assessments of parasite health and the kinetics of antimalarial action during drug discovery

Adenosine 5’ triphosphate (ATP) is a molecule central to life for its role as the cellular energy currency, and a purine nucleotide which serves as a building block of RNA. Thus, on the backdrop of an indispensible intracellular role of ATP, its identification as an extracellular signaling molecule in early 1970s came as a surprise. A novel doctrine, termed as ‘purinergic signaling’, was thus put forth. By definition, purinergic signaling consists of the signaling events triggered by binding of extracellular ATP- a purine nucleotide, and its breakdown products (viz., ADP, AMP, and adenosine) to their cognate receptors, which in turn are termed as ‘purinergic receptors’. Based on their ligand affinity, purinergic receptors are classified into two groups- P1 and P2 receptors. P2 receptors are further subclassified as P2X and P2Y receptors. Till date, four P1 receptors (viz. A1, A2a, A2b, and A3), seven P2X receptors (P2X1-7), and eight P2Y receptors (P2Y1, P2Y2, P2Y4, P2Y6, P2Y11, P2Y12, P2Y13, and P2Y14) have been cloned and characterized. Conceptually, the first step of purinergic signaling is the release of ATP from an intact cell on encountering a stimulant or a modulator. The main mechanisms of such cellular ATP release include vesicular exocytosis and the release through conductive channels. ATP thus released, binds to its cognate receptors (i.e. P2X receptors, and certain P2Y receptors) and triggers the ‘purinergic signaling’ pathway that modulates the cellular response. In addition to purinergic receptors, cells also express ATP degrading enzymes on their surface, which break ATP down into ADP, AMP, and adenosine. ADP and adenosine, in turn, bind to their cognate receptors (certain P2Y receptors, and P1 receptors respectively) and further contribute to shaping the cellular response to a given cue. Thus, purinergic signaling is a highly dynamic process with pleiotropic downstream effects. First demonstrated in the context of neurotransmission, the phenomenon of purinergic signaling is now widely recognized and has been shown to play a role in regulating functional responses of cells of diverse origins, immune cells being one of them. Purinergic signaling in lymphocytes- an important subset of immune cells- is a common thread for the present research exercise, wherein we have addressed two sets of questions, one of academic curiosity and the other of clinical interest. In the former and the major part, we have examined whether purinergic signaling plays a role in functional aspects of ‘gamma delta (γδ) T cells’, which represent a unique subset of lymphocytes. Whereas, the latter part elaborates on the already identified involvement of purinergic signaling in T cell stimulatory action of ‘hypertonic saline (HS)’, which is used to treat trauma patients. The thesis, thus, is divided into five parts- the ‘Introduction’, ‘Aims and Scope of the study’, ‘Chapter 1’, ‘Chapter 2’, and ‘Summary of the work’. Understanding the questions posed in the present context, strategy designed to answer them, and eventually the experimental results answering these questions invoke basic knowledge of purinergic signaling, which has been attempted to be conferred through the ‘Introduction’ section. The discovery of purinergic signaling, its central theme, and individual molecular players involved in this signaling pathway are highlighted here. From the viewpoint of the present research endeavor, salient findings from the current literatureabout the involvement of purinergic signaling in the functional activities of various subsets of immune cells- are reviewed towards the end of this section. The ‘Introduction’ is followed by definition of the objectives for the present exercise, which are enlisted under ‘Aims and scope of the study’. Here, a brief overview of the background data that led us towards these objectives precedes the actual list of questions which we have approached. Purinergic signaling has been shown to play a role in the activation of ‘conventional αβ T’ cells. So we asked whether a similar purinergic signaling pathway also operates in unconventional γδ T cells. Thus, ‘Chapter 1’ is dedicated to answering the first set of questions about the role of purinergic signaling in γδ T cell activation. The chapter starts off by introducing γδ T cells. The topics such as discovery of γδ T cells, ontology, development, diversity, and distribution of these cells, and most importantly- their antigenic specificity and response are reviewed herein. The details of the experimental procedures employed to answer the defined objectives follow this introduction. We have carried out our experiments on γδ T cells in human circulation. For in vitro stimulation, we have used anti-CD3 + anti-CD28-coated beads (beads) or isopentenyl pyrophosphate (IPP), a γδ T cell specific stimulant. We observed that, circulating human γδ T cells rapidly release ATP on stimulation with beads or IPP. Pannexin-1 and connexin hemichannels, as well as vesicular exocytosis contribute to the ATP release. Real time RT-PCR data revealed that γδ T cells predominantly express purinergic receptors A2a, P2X1, P2X4, P2X7, and P2Y11. Of these, the inhibition of P2X4 receptors downregulated cytokine expression by γδ T cells post- in vitro stimulation, and also inhibited cytotoxic activity of γδ T cells towards Daudi cells. Selective translocation of P2X4 receptors to the immunological synapse was seen to be the underlying mechanism for these effects. Collectively, these data suggested that autocrine/paracrine purinergic signaling through P2X4 receptors indeed plays an important role in the functional aspects of circulating human γδ T cells. The experimental results are compiled in ‘Chapter 1’; which concludes with the ‘Discussion’ on the mentioned findings, and possible in vivo applications. ‘Chapter 2’ deals with the role of purinergic signaling in HS resuscitation. In addition to restoring the hemodynamic parameters, fluid replacement with small volumes of concentrated NaCl solution (HS) has been reported to reverse the suppression of T cells commonly found in the trauma subjects. Through an in vitro study using Jurkat cells as a model for primary human T cells, it has been shown earlier that, on HS exposure T cells release ATP- which binds to P2X7 receptors and promotes calcium influx. HS treatment also elicits phosphorylation of p38; and put together, Ca2+ influx and phosphorylated p38 synergize with TCR-induced stimulation resulting in the enhancement of transcriptional upregulation of IL-2. However, the mechanism of release of ATP on HS treatment and the possible involvement of P2X1 and P2X4 receptors expressed by T cells had not been addressed in this study. These very questions thus formed the objectives of the second part of present work. Experiments aimed to answer these questions showed that on HS treatment, Jurkat cells release ATP through pannexin-1 hemichannels. The released ATP binds to purinergic receptors P2X1, P2X4, and P2X7. This in turn triggers the downstream signaling cascade leading to phosphorylation of p38 and upregulation of IL-2 transcription, hence augmenting the T cell function. An overview of HS resuscitation, experimental protocols and results, and the discussion on the pathophysiological relevance of these findings comprise ‘Chapter 2’. Hence, we have found the answers to the questions we began with. The results are listed in a point-wise manner under the ‘Summary of the work’. Taken together, our data shows that: (i) Purinergic signaling does play a role in the functional aspects of circulating human γδ T cells. The release of ATP by γδ T cells post-stimulation, and autocrine/paracrine signaling through P2X4 receptors are the main components in this context. (ii) ATP release through pannexin-1 hemichannels, and autocrine/paracrine signaling through P2X1, P2X4, and P2X7 receptors underlie the mechanism of action of HS.

Glycogen Synthase Kinase 3 (GSK3), a serine/threonine kinase initially characterized in the context of glycogen metabolism, has been repeatedly realized as a multitasking protein that can regulate numerous cellular events in both metazoa and protozoa. I recently found GSK3 plays a role in regulating chemotaxis, a guided cell movement in response to an external chemical gradient, in one of the best studied model systems for chemotaxis - Dictyostelium discoideum. It was initially found that comparing to wild type cells, gsk3- cells showed aberrant chemotaxis with a significant decrease in both speed and chemotactic indices. In Dictyostelium, phosphatidylinositol 3,4,5-triphosphate (PIP3) signaling is one of the best characterized pathways that regulate chemotaxis. Molecular analysis uncovered that gsk3- cells suffer from high basal level of PIP3, the product of PI3K. Upon chemoattractant cAMP stimulation, wild type cells displayed a transient increase in the level of PIP3. In contrast, gsk3- cells exhibited neither significant increase nor adaptation. On the other hand, no aberrant dynamic of phosphatase and tensin homolog (PTEN), which antagonizes PI3K function, was observed. Upon membrane localization of PI3K, PI3K become activated by Ras, which will in turn further facilitate membrane localization of PI3K in an F-Actin dependent manner. The gsk3- cells treated with F-Actin inhibitor Latrunculin-A showed no significant difference in the PIP3 level. I also showed GSK3 affected the phosphorylation level of the localization domain of PI3K1 (PI3K1-LD). PI3K1-LD proteins from gsk3- cells displayed less phosphorylation on serine residues compared to that from wild type cells. When the potential GSK3 phosphorylation sites of PI3K1-LD were substituted with aspartic acids (Phosphomimetic substitution), its membrane localization was suppressed in gsk3- cells. When these serine residues of PI3K1-LD were substituted with alanine, aberrantly high level of membrane localization of the PI3K1-LD was monitored in wild type cells. Wild type, phosphomimetic, and alanine substitution of PI3K1-LD fused with GFP proteins also displayed identical localization behavior as suggested by the cell fraction studies. Lastly, I identified that all three potential GSK3 phosphorylation sites on PI3K1-LD could be phosphorylated in vitro by GSK3.

Malaria is a fatal tropical disease affecting billions of people in impoverished countries world-wide. An alarming fact is that a child in Africa dies of malaria every 30 seconds that amounts to 2500 children per day (www.who.int/features/factfiles). Malaria is caused by the intraerythrocytic forms of Plasmodium species, notably P. falciparum, P. vivax, P. ovale and P. malariae (Hyde 2007). The spread of drug-resistant strains, failure of vector control programs, rapid growth rate of the parasite, and lack of a vaccine have further exacerbated the effects of malaria on economic development and human health. It is therefore imperative that novel drug targets are developed or current antimalarial drugs optimized (Foley and Tilley 1998). One such target is folate biosynthesis, given that folates and their derivatives are required for the survival of organisms (Muller et al. 2009). DHFR and DHPS are currently the only folate targets exploited however, their antifolate drugs are almost useless against parasite resistant strains. As such, guanosine-5’triphosphate cyclohydrolase I (GTPCHl) among other antifolate candidates are considered for intervention (Lee et al. 2001). Knock-out studies (of P. falciparum gtpchI) resulted in the suppression of DHPS activity (Nzila et al. 2005). Additionally, gtpchI amplified 11-fold in P. falciparum strains resistant to antifolates due to mutations in dhps and dhfr and this may be a mechanism for the compensation of reduced flux of folate intermediates (Kidgell et al. 2006; Nair et al. 2008). Over-expression of P. falciparum proteins in E. coli remains a challenge mainly due to the A+T rich Plasmodium genome resulting in a codon bias. This results in the expression of recombinant proteins as insoluble proteins sequestered in inclusion bodies (Carrio and Villaverde 2002; Mehlin et al. 2006; Birkholtz et al. 2008a). Comparative expression studies were conducted of native GTPCHI (nGTPCHI), codon optimized GTPCHI (oGTPCHI) and codon harmonized (hGTPCHI) in various E. coli cell lines, using alternative media compositions and co-expression with Pfhsp70. The nGTPCHI protein did not express because the gene consisted of codons rarely used by E. coli (codon bias). The expression levels of purified hGTPCHI were a greater in comparison to oGTPCHI using the different expression conditions. This is because codon-harmonization involves substituting codons to replicate the codon frequency preference of the target gene in P. falciparum, as such the translation machinery matches that of Plasmodium (Angov et al. 2008). Furthermore, greater expression levels of GTPCHI were achieved in the absence of Pfhsp70 due to expression of a possible Nterminal deletion product or E. coli protein. Purification conditions could be improved to obtain homogenous GTPCHI and further analysis (mass spectrometry and enzyme activity assays) would be required to determine the nature of soluble GTPCHI obtained. To improve the expression of soluble proteins the wheat germ expression system was used as an alternate host. However, GTPCHI expression was not effective, possibly due to degradation of mRNA template or the absence of translation enhancer elements. / Dissertation (MSc)--University of Pretoria, 2010. / Biochemistry / unrestricted

This thesis examines the hypothesis that human erythrocyte net sugar transport is the sum of two serial processes: sugar translocation followed by interaction of newly imported sugar with an intracellular binding complex from which sugar dissociates into the bulk cytosol. This hypothesis suggests that steady-state transport measurements in the human erythrocyte do not accurately reflect the intrinsic catalytic features of the glucose transporter and unless correctly interpreted, may lead to apparent inconsistencies in the operational behavior of the human erythrocyte sugar transport system. Our results support this proposal by demonstrating that although sugar transport measurements in human red blood cells suggest that transport is catalytically asymmetric, ligand binding measurements indicate that transport must be symmetric. In order to examine the serial compartments hypothesis, we set out to determine the following: 1) identify the component(s) of the proposed sugar binding complex, 2) determine whether cytosolic ATP levels and transporter quaternary structure affect sugar binding to the sugar binding complex, and 3) determine whether the sugar binding site(s) are located within or outside the cell. We present findings which support the hypothesis that the sugar binding complex is in fact the sugar transport protein, GLUT1. The number of sugar binding sites and the release of sugar from the GLUT1 complex are regulated by ATP and by GLUT1 quaternary structure. The sugar binding sites are located on a cytoplasmic domain of the GLUT1 complex. We show how these observations can account for the apparent complexity of erythrocyte sugar transport and its regulation by ATP.

Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2017-2018 / Les nanomatériaux attirent l’attention dans le domaine biomédical en raison de leurs propriétés liées à leur taille. Les nanoparticules métalliques, plus particulièrement, possèdent un plasmon de surface localisé leur conférant une signature d’extinction de la lumière caractéristique. Bien que l’argent possède de meilleures propriétés plasmoniques, l’or est habituellement préféré pour des applications médicales, puisqu’il est stable en conditions biologiques en plus d’être biocompatible. Ce projet a donc pour objectif d’exploiter les propriétés des nanoparticules d’or dans le cadre de deux applications : le relargage contrôlé de médicaments et la détection d’analytes en milieu cellulaire. Dans un premier temps, des nanobâtonnets d’or possédant une bande plasmonique dans le proche infrarouge sont utilisés afin de développer des nano-véhicules pour le transport actif de médicaments. Ces bâtonnets sont entourés d’une couche de polymère thermosensible permettant l’encapsulation et le transport de biomolécules jusqu’au site biologique d’intérêt. Un laser dans le proche infrarouge est utilisé comme stimulus externe pour déclencher le relargage des molécules bioactives en causant une augmentation locale de température autour des nanobâtonnets. Ces nouveaux modules sont développés en collaboration avec le Dr. Patrick Mathieu à l’Institut universitaire de cardiologie et de pneumologie de Québec pour étudier la décalcification des valves cardiaques. Le second projet vise à développer un outil micrométrique pour la détection d’adénosine 5’-triphosphate dans l’environnement des cellules, et ce, en collaboration avec les groupes des professeurs Jean-François Masson de l’Université de Montréal et Joachim Spatz de l’Université d’Heidelberg en Allemagne. Cet outil consiste en une micropipette de verre recouverte de nanoparticules d’or fonctionnalisée avec un aptamère fluorescent qui possède une grande affinité pour l’ATP. Lorsque l’aptamère se lie à sa cible, il se replie sur lui-même, rapprochant ainsi le fluorophore de la surface plasmonique. En microscopie de fluorescence, il est possible de mesurer l’extinction de fluorescence résultant de ce changement de conformation pour quantifier la concentration d’ATP localement. / Nanomaterials have attracted a great deal of attention in the fields of biology and medicine because of their unique properties arising from their small size. Metallic nanoparticles, more precisely, can interact with light in various ways as a result of their localized surface plasmon. Even though silver is the best plasmonic material, gold is usually preferred for medical applications because it is both more stable in biological conditions and biocompatible. Therefore, the objective of this project is to take advantage of the properties of gold nanoparticles in two distinct applications: controlled drug delivery and detection of biomolecules in cell cultures. First, gold nanorods with a plasmon in the near-infrared region are used to develop new nanocarriers for active drug transport. These nanorods are covered with a thermosensitive polymeric shell allowing the encapsulation of bioactive molecules. A near-infrared laser is used as an external stimulus to trigger the release of the drug ¬once the nanocarriers have reached the desired biological location by locally increasing the temperature of the gold nanorods. These new modules are developed in collaboration with Dr. Patrick Mathieu from the Quebec Heart and Lung Institute of Université Laval in order to study the decalcification of heart valves. The second project aims at developing a micrometric tool for the detection of adenosine 5’-triphosphate in the vicinity of live cells, in collaboration with the groups of Prof. Jean-François Masson of Université de Montréal and Prof. Joachim Spatz of Heidelberg University in Germany. This tool consists of a glass micropipette covered with gold nanoparticles and functionalized with a fluorescent ATP-selective aptamer. Upon binding to its target, the aptamer changes conformation to form a hairpin, which brings the fluorophore closer to the plasmonic surface. Using fluorescence microscopy, it is possible to measure the fluorescence quenching resulting from this change of conformation, and thus to quantify the concentration of ATP locally.

No description available.