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Pui Lan Wong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (Leaves 109-122). / Abstract --- p.i / Acknowledgements --- p.iii / Chapter Chapter1 --- Introduction / Chapter 1.1 --- A general introduction on mast cells --- p.1 / Chapter 1.2 --- Activation of mast cells --- p.6 / Chapter 1.3 --- Mediators of mast cells --- p.18 / Chapter 1.4 --- Usage of β-adrenoceptor agonists in asthma therapy --- p.26 / Chapter 1.5 --- Aim of this study --- p.32 / Chapter Chapter2 --- Materials and methods / Chapter 2.1 --- Chemicals --- p.42 / Chapter 2.2 --- Buffers and stock solutions --- p.43 / Chapter 2.3 --- Source of mast cells --- p.45 / Chapter 2.4 --- Animal sensitization --- p.45 / Chapter 2.5 --- Isolation of mast cells --- p.46 / Chapter 2.6 --- Procedure for the investigation of the effects of adrenoceptor agonists on histamine release from mast cells --- p.48 / Chapter 2.7 --- Procedure for the investigation of propranolol antagonism --- p.49 / Chapter 2.8 --- Histamine assay --- p.50 / Chapter 2.9 --- Data analysis --- p.50 / Chapter Chapter3 --- Results / Chapter 3.1 --- Establishment of experimental conditions --- p.53 / Chapter 3.2 --- The effects of β-agonists on immunologically induced histamine release from guinea pig lung mast cells --- p.54 / Chapter 3.3 --- The effects of β-agonists and two anti-allergic drugs on immunologically induced histamine release from guinea pig lung mast cells --- p.56 / Chapter 3.4 --- The effects of β2-agonists on histamine release induced by non-immunological agents from guinea pig lung mast cells --- p.56 / Chapter 3.5 --- Antagonism by propranolol on the effects of β2-agonists on histamine release from guinea pig lung mast cells --- p.57 / Chapter 3.6 --- The effects of β2-agonists on immunologically induced histamine release from rat peritoneal mast cells --- p.58 / Chapter 3.7 --- The effects of β2-agonists on immunologically induced histamine release from human lung mast cells --- p.58 / Chapter 3.8 --- "Comparison of the effects of β2-agonists on immunologically induced histamine release from mast cells isolated from the rat peritoneum, the guinea pig lung and the human lung" --- p.59 / Chapter Chapter4 --- Discussion / Chapter 4.1 --- The effects of β-agonists on immunologically induced histamine release from guinea pig lung mast cells --- p.89 / Chapter 4.2 --- The effects of β2-agonists and two anti-allergic drugs on immunologically induced histamine release from guinea pig lung mast cells --- p.97 / Chapter 4.3 --- The effects of novel β2-agonists on histamine release induced by non-immunological agents from guinea pig lung mast cells --- p.99 / Chapter 4.4 --- The study of propranolol --- p.100 / Chapter 4.5 --- The heterogeneity of mast cells --- p.103 / Chapter Chapter5 --- General conclusion --- p.107 / References --- p.109

Os problemas decorrentes de doenças alérgicas é tema em destaque atualmente devido ao aumento de pessoas que vêm apresentando sintomas e sofrendo as consequências de mudanças aceleradas nos costumes da nossa sociedade. Apesar das diversas terapias oferecidas, pacientes alérgicos ainda sofrem com efeitos colaterais decorrentes do uso de medicamentos anti-alérgicos. Assim, a busca por novas alternativas que possam amenizar os sintomas alérgicos torna-se relevante. As substâncias naturais tem sido alvo de intensa investigação devido às propriedades farmacológicas no tratamento de diversas doenças incluindo as alérgicas. Neste contexto, este trabalho foi focado no extrato Vimang e seu componente majoritário, a mangiferina (Mgf), que tem apresentado atividades biológicas diversas. Sabendo-se que a atividade biológica de um extrato pode ser potencializada pelo sinergismo entre seus componentes, foi avaliado o efeito sinérgico de substâncias isoladas do Vimang, tais como mangiferina, quercetina, catequina, ácido gálico e benzóico. Esses componentes foram combinados e as misturas avaliadas quanto à capacidade em inibir a desgranulação mastocitária. O Vimang, a quercetina e mangiferina inibem a desgranulação mastócitária enquanto catequina, ácido gálico e benzóico não são ativos; e porisso, não foram incluídos na determinação do isobolograma de aditividade, adotado no estudo de sinergismo. O isobolograma de aditividade mostra sinergismo para as concentrações de mangiferina iguais a 5, 10, 20 e 40 ?M e quercetina iguais a 0,2, 1 e 1,6 ?M; e mostra antagonismo para mangiferina 80 ?M e quercetina 0,4 e 0,8 ?M. Tais resultados sugerem que altas concentrações de mangiferina atrapalham a interação sinérgica entre estas substâncias e altas concentrações de quercetina exercem um efeito contrário, ou seja, favorecem o sinergismo entre quercetina e mangiferina. A baixa solubilidade de flavonóides em meio fisiológico levou ao estudo da interação da Mgf com lipossomos de Dimiristoil-L-?-Fosfatidilcolina (DMPC) para aplicação nos ensaios biológicos. A Interação da Mgf com lipossomos de DMPC, bem como a estabilidade lipossomal, foram avaliadas quanto aos efeitos de pH, força iônica e presença de colesterol. O pH influencia a eficiência de incorporação (EI) da Mgf que é maior em pHs ácidos. Em soluções de pH ácido ou fisiológico há aumento de tamanho do lipossomo na presença de Mgf, o que reforça a hipótese de interação desta com a bicamada lipídica. O aumento da força iônica, na ausência de Mgf, diminui a estabilidade do lipossomo. Na ausência de sal, a Mgf favorece a formação de agregados e diminui a estabilidade dos lipossomos e na presença de sal, a Mgf previne a agregação e estabiliza os agregados lipossomais. A EI da Mgf nos lipossomos de DMPC preparados pelo método da injeção etanólica, em pH fisiológico, foram ao redor de 13%. A tentativa de otimizar a EI foi realizada pela adição de colesterol em diferentes proporções lipídio:colesterol. Um aumento de 13% para 17% foi observado para a proporção DMPC:colesterol (9:1). A Mgf livre inibe a desgranulação dos mastócitos de forma concentração-dependente; mas a presença de lipossomos, preparados pelo método da injeção etanólica não altera significativamente esse perfil. A EI da mangiferina em lipossomos de DMPC:colesterol (9:1), preparados pelo método do filme lipídico, foi igual a 45%. Os resultados de potencial antialérgico, para este caso, mostraram que os lipossomos de DMPC favorecem o potencial antialérgico da Mgf em concentrações acima de 25 ?M. Esses resultados abrem perspectivas na busca de sistemas lipossomais mais estáveis e que possam ser aplicados em ensaios biológicos in vitro e in vivo. / The problems due to allergic diseases are currently a highlighted topic due to the increase of people who are showing symptoms and suffering the consequences of rapid changes in the habits of our society. Despite various therapies offered, allergic patients still suffer side effects from the use of anti-allergic drugs. Thus, the search for new alternatives that can alleviate the allergic symptoms becomes relevant. Natural substances have been the subject of intense research due to the pharmacological properties in the treatment of several diseases, including allergic ones. In this context, this work was focused on Vimang extract and its major component, the mangiferin (Mgf), which has shown several biological activities. Given that the biological activity of an extract can be enhanced by the synergism between its components, the synergistic effect of compounds isolated from Vimang such as mangiferin, quercetin, catechin, gallic acid and benzoic acid was evaluated. These components were combined and the mixtures tested for their ability to inhibit mast cell degranulation. The Vimang, quercetin and mangiferin inhibit mast cell degranulation while catechin, gallic acid and benzoic acid are not active and for that reason they were not included in the determination of the isobologram adopted in the synergism study. The isobologram of additivity shows synergism for the concentration of mangiferin equal to 5, 10, 20 and 40 ?M and quercetin equal 0.2, 1 and 1.6 ?M, and shows antagonism for mangiferin 80 ?M and quercetin 0.4 and 0.8 ?M. The low solubility of flavonoids in physiological medium led to the study of the interaction of Mgf with liposomes of L-?-dimyristoyl-phosphatidylcholine (DMPC) for application in biological assays. The interaction of Mgf with DMPC liposomes as well as the liposomal stability was evaluated considering the effects of pH, ionic strength and cholesterol presence. The pH influences the incorporation efficiency (IE) of mangiferin, which is higher in acidic pHs. In solutions of acidic or physiological pH, the liposome size increases in the presence of Mgf, which reinforces the hypothesis of interaction of Mgf with the lipid bilayer. The increased ionic strength in the absence of Mgf decreases the stability of the liposome. In the absence of salt, Mgf favors the formation of aggregates and decreases the stability of the liposomes. When in presence of salt, Mgf prevents the aggregation and stabilizes the liposomal aggregates. The IE of mangiferin in DMPC prepared by the ethanol injection method, at physiological pH, were around 13%. The attempt to optimize the IE was performed by the addition of cholesterol in different proportions lipid:cholesterol. An increase from 13% to 17% was observed for the proportion of DMPC:cholesterol (9:1). Free mangiferin inhibits mast cells degranulation in a dose-dependent manner, but the presence of liposomes prepared by the ethanol injection method does not significantly change this profile. The IE of mangiferin in liposomes of DMPC:cholesterol (9:1), prepared by the method of lipidic film was equal to 45%.The results of antiallergic potential in this case show that DMPC liposomes favor the mangiferin antiallergic potential at concentrations above 25 mM. These results open perspectives in the search for more stable liposomal systems and can be applied to biological assays in vitro and in vivo.

Os problemas decorrentes de doenças alérgicas é tema em destaque atualmente devido ao aumento de pessoas que vêm apresentando sintomas e sofrendo as consequências de mudanças aceleradas nos costumes da nossa sociedade. Apesar das diversas terapias oferecidas, pacientes alérgicos ainda sofrem com efeitos colaterais decorrentes do uso de medicamentos anti-alérgicos. Assim, a busca por novas alternativas que possam amenizar os sintomas alérgicos torna-se relevante. As substâncias naturais tem sido alvo de intensa investigação devido às propriedades farmacológicas no tratamento de diversas doenças incluindo as alérgicas. Neste contexto, este trabalho foi focado no extrato Vimang e seu componente majoritário, a mangiferina (Mgf), que tem apresentado atividades biológicas diversas. Sabendo-se que a atividade biológica de um extrato pode ser potencializada pelo sinergismo entre seus componentes, foi avaliado o efeito sinérgico de substâncias isoladas do Vimang, tais como mangiferina, quercetina, catequina, ácido gálico e benzóico. Esses componentes foram combinados e as misturas avaliadas quanto à capacidade em inibir a desgranulação mastocitária. O Vimang, a quercetina e mangiferina inibem a desgranulação mastócitária enquanto catequina, ácido gálico e benzóico não são ativos; e porisso, não foram incluídos na determinação do isobolograma de aditividade, adotado no estudo de sinergismo. O isobolograma de aditividade mostra sinergismo para as concentrações de mangiferina iguais a 5, 10, 20 e 40 ?M e quercetina iguais a 0,2, 1 e 1,6 ?M; e mostra antagonismo para mangiferina 80 ?M e quercetina 0,4 e 0,8 ?M. Tais resultados sugerem que altas concentrações de mangiferina atrapalham a interação sinérgica entre estas substâncias e altas concentrações de quercetina exercem um efeito contrário, ou seja, favorecem o sinergismo entre quercetina e mangiferina. A baixa solubilidade de flavonóides em meio fisiológico levou ao estudo da interação da Mgf com lipossomos de Dimiristoil-L-?-Fosfatidilcolina (DMPC) para aplicação nos ensaios biológicos. A Interação da Mgf com lipossomos de DMPC, bem como a estabilidade lipossomal, foram avaliadas quanto aos efeitos de pH, força iônica e presença de colesterol. O pH influencia a eficiência de incorporação (EI) da Mgf que é maior em pHs ácidos. Em soluções de pH ácido ou fisiológico há aumento de tamanho do lipossomo na presença de Mgf, o que reforça a hipótese de interação desta com a bicamada lipídica. O aumento da força iônica, na ausência de Mgf, diminui a estabilidade do lipossomo. Na ausência de sal, a Mgf favorece a formação de agregados e diminui a estabilidade dos lipossomos e na presença de sal, a Mgf previne a agregação e estabiliza os agregados lipossomais. A EI da Mgf nos lipossomos de DMPC preparados pelo método da injeção etanólica, em pH fisiológico, foram ao redor de 13%. A tentativa de otimizar a EI foi realizada pela adição de colesterol em diferentes proporções lipídio:colesterol. Um aumento de 13% para 17% foi observado para a proporção DMPC:colesterol (9:1). A Mgf livre inibe a desgranulação dos mastócitos de forma concentração-dependente; mas a presença de lipossomos, preparados pelo método da injeção etanólica não altera significativamente esse perfil. A EI da mangiferina em lipossomos de DMPC:colesterol (9:1), preparados pelo método do filme lipídico, foi igual a 45%. Os resultados de potencial antialérgico, para este caso, mostraram que os lipossomos de DMPC favorecem o potencial antialérgico da Mgf em concentrações acima de 25 ?M. Esses resultados abrem perspectivas na busca de sistemas lipossomais mais estáveis e que possam ser aplicados em ensaios biológicos in vitro e in vivo. / The problems due to allergic diseases are currently a highlighted topic due to the increase of people who are showing symptoms and suffering the consequences of rapid changes in the habits of our society. Despite various therapies offered, allergic patients still suffer side effects from the use of anti-allergic drugs. Thus, the search for new alternatives that can alleviate the allergic symptoms becomes relevant. Natural substances have been the subject of intense research due to the pharmacological properties in the treatment of several diseases, including allergic ones. In this context, this work was focused on Vimang extract and its major component, the mangiferin (Mgf), which has shown several biological activities. Given that the biological activity of an extract can be enhanced by the synergism between its components, the synergistic effect of compounds isolated from Vimang such as mangiferin, quercetin, catechin, gallic acid and benzoic acid was evaluated. These components were combined and the mixtures tested for their ability to inhibit mast cell degranulation. The Vimang, quercetin and mangiferin inhibit mast cell degranulation while catechin, gallic acid and benzoic acid are not active and for that reason they were not included in the determination of the isobologram adopted in the synergism study. The isobologram of additivity shows synergism for the concentration of mangiferin equal to 5, 10, 20 and 40 ?M and quercetin equal 0.2, 1 and 1.6 ?M, and shows antagonism for mangiferin 80 ?M and quercetin 0.4 and 0.8 ?M. The low solubility of flavonoids in physiological medium led to the study of the interaction of Mgf with liposomes of L-?-dimyristoyl-phosphatidylcholine (DMPC) for application in biological assays. The interaction of Mgf with DMPC liposomes as well as the liposomal stability was evaluated considering the effects of pH, ionic strength and cholesterol presence. The pH influences the incorporation efficiency (IE) of mangiferin, which is higher in acidic pHs. In solutions of acidic or physiological pH, the liposome size increases in the presence of Mgf, which reinforces the hypothesis of interaction of Mgf with the lipid bilayer. The increased ionic strength in the absence of Mgf decreases the stability of the liposome. In the absence of salt, Mgf favors the formation of aggregates and decreases the stability of the liposomes. When in presence of salt, Mgf prevents the aggregation and stabilizes the liposomal aggregates. The IE of mangiferin in DMPC prepared by the ethanol injection method, at physiological pH, were around 13%. The attempt to optimize the IE was performed by the addition of cholesterol in different proportions lipid:cholesterol. An increase from 13% to 17% was observed for the proportion of DMPC:cholesterol (9:1). Free mangiferin inhibits mast cells degranulation in a dose-dependent manner, but the presence of liposomes prepared by the ethanol injection method does not significantly change this profile. The IE of mangiferin in liposomes of DMPC:cholesterol (9:1), prepared by the method of lipidic film was equal to 45%.The results of antiallergic potential in this case show that DMPC liposomes favor the mangiferin antiallergic potential at concentrations above 25 mM. These results open perspectives in the search for more stable liposomal systems and can be applied to biological assays in vitro and in vivo.

<p>Akrilamid je toksična hemijska supstanca koja ima vrlo &scaron;iroku primenu u hemijskoj industriji, a 2002. godine otkriveno je njegovo prisustvo u namirnicima bogatim skrobom koje se pripremaju na visokim temperaturama. U poslednjh desetak godina primećen je veliki porast gastrointestinalnih tegoba u ljudskoj populaciji. Cilj istraživanja bio je ispitati patohistolo&scaron;ke promene u tkivu želuca pacova soja Wistar izazvanih peroralnim aplikovanjem akrilamida i na taj način povući paralelu sa mogućim gastrointestinalnim tegobama nastalim kao posledica konzumiranja hrane bogate akrilamidom. U istraživanju je ispitivano 6 grupa od po 5 eksperimentalnih životinja (pacovi soja Wistar). Dve kontrolne grupe kojima je peroralno aplikovana destilovana voda i koje su žrtvovane posle 24h i 72h; dve eksperimentalne kojima je peroralno aplikovan akrilamid u dnevnoj dozi od 25 mg/kg i koje su žrtvovane posle 24h i 72h; dve eksperimentalne grupe kojima je peroralno aplikovan akrilamid u dnevnoj dozi od 50 mg/kg i koje su žrtvovane posle 24h i 72h. Na histolo&scaron;kom materijalu tkiva želuca primenjena je kvalitativna histolo&scaron;ka analiza pod svetlosnim mikroskopom, semikvantitativna procena tipa mucina u epitelnim ćelijama sluznice želuca, prisustvo limfocita i granulocita u sluznici želuca, stereolo&scaron;ka merenja pojedinih kompartmana zida želuca, linearna merenja broja i veličine ganglijskih ćelija u Maissner-ovom i Auerbach-ovom nervnom pleksusu, kao i broj mastocita u lamini propriji sluznice i podsluznici želuca. Dobijene vrednosti merenih parametara su potom statistički obrađene. Nastale promene na tkivu želuca pacova soja Wistar se ogledaju u vidu blagog direktnog o&scaron;tećenja povr&scaron;nog epitela sa propratnom blagom inflamatornom reakcijom i blagom degranulacijom mastocita. U Maissner-ovom i Auerbach-ovom nervnom pleksusu su smanjene volumenske gustine nervnih vlakana i ganglijskih ćelija, kao i broj i veličina ganglijskih ćelija. Direktno toksično delovanje na epitel dovodi do posledične obnove epitela, te je potvrđeno prisustvo nezrelijih oblika mukoproduktivnih ćelija koje sadrže kisele, AB pozitivne mucine. Ispitani inflamatorni i degenerativni parametri pokazuju pozitivnu korelaciju u odnosu na dozu i/ili dužinu ekspozicije akrilamidu. Primena akrilamida peroralno pokazala je da postoje patohistolo&scaron;ke promene na tkivu želuca u vidu direktnog toksičnog o&scaron;tećenja epitela, inflamatorne reakcije i o&scaron;tećenja nervnih pleksusa. Poznavanjem mehanizma delovanja ove toksične materije moguće je primeniti adekvatnu prevenciju u ishrani i izvr&scaron;iti odgovarajući izbor terapijskih metoda.</p> / <p>Acrylamide is a toxic chemical substance with wide implementation in chemical industry. In 2002 it was discovered the presence of acrylamide in foods rich in starch which are prepared at high temperatures. In the last ten years there is a large increase in gastrointestinal illnesses in human population. The aim of this study was to investigate the histopathological changes in the gastric tissue in Wistar rats induced with injection of oral acrylamide and thus draw a parallel with possible gastrointestinal problems arising as a result of the consumption of foods rich in acrylamide. The research was carried out 6 groups of 5 experimental animals (Wistar rats). Two control groups that are orally concomitant application of distilled water and which were sacrificed after 24h and 72h; two experimental groups which are orally administrated acrylamide in a daily dose of 25 mg / kg and that were sacrificed after 24h and 72h; two experimental groups which were orally administrated acrylamide in a daily dose of 50 mg / kg and that were sacrificed after 24h and 72h. On histological gastric tissue material is applied qualitative histological analysis by light microscopy, semi-quantitative assessment of the type of mucin in epithelial cells of the stomach lining, the presence of lymphocytes and granulocytes in gastric mucosa, stereological measurements of individual compartments of the stomach wall, linear measuring the number and size of ganglion cells in the Maissner and Auerbach&#39;s nerve plexus, and the number of mast cells in the lamina propria of the mucosa and in the submucosis of the stomach. Obtained values of measured parameters were statistically processed. Histological changes in the stomach tissue of Wistar rats are seen as a direct slight damage of the surface epithelium, with accompanynig mild inflammatory reaction and the degranulation of mast cells. The Meissner&#39;s and Auerbach&#39;s nerve plexus decreased volume density of nerve fibers and ganglion cells, as well as the number and size of the ganglion cells. Directly toxic effect on epithelium leads to the result of the reconstruction of the epithelium, which is confirmed by the presence of immature form of mucoproductive cells which contain acid, AB positive mucins. Examined inflammatory and degenerative parameters show a positive correlation with respect to dose and / or a time of exposition to acrylamide. Acrylamide oral application revealed that there are histologic changes in the stomach tissue in the form of a direct toxic damage to the epithelium, inflammatory reaction and damage to the nerve plexus. Knowing the mechanism of action of these toxic substances allows to apply adequate prevention in nutrition and make an appropriate choice of therapeutic methods.</p>