• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 59
  • 11
  • 5
  • 4
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 95
  • 27
  • 12
  • 9
  • 9
  • 9
  • 8
  • 7
  • 6
  • 6
  • 6
  • 6
  • 5
  • 5
  • 4
  • 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.
71

Alpha₁-adrenoceptor-mediated phosphoinositide breakdown and inotropic responses in right ventricles of streptozotocin-diabetic rats

Xiang, Hong January 1990 (has links)
The morbidity of and the mortality from cardiac disease are higher in diabetic patients. Clinical and experimental evidence suggests that diabetes-induced changes at the level of myocardium can, at least partially, contribute to these cardiac problems. The mechanism(s) involved in this diabetic cardiomyopathy is still unclear, but one defect appears to occur in the alpha₁-adrenoceptor system. Altered myocardial sensitivity and responsiveness to alpha₁-adrenoceptor agonists have been reported in experimental diabetes mellitus. Stimulation of alpha₁-adrenoceptors is known to produce a positive inotropic effect and has been recently shown to stimulate the hydrolysis of phosphoinositides. To evaluate the possibility that the changes in the inotropic responsiveness to alpha₁-adrenoceptor stimulation in the diabetic heart could be linked to altered alpha₁-adrenoceptor-stimulated phosphoinositide turnover and further to the development of diabetic cardiomyopathy, we studied contractility and receptor-stimulated phosphoinositide turnover following norepinephrine (in the presence of propranolol) stimulation in right ventricles from male Wistar rats (200-225 g) which were made diabetic with streptozotocin (55 mg/kg, i.v.). Rats were sacrificed six weeks after the induction of diabetes. Diabetic rats were characterized by decreased body weight gain, hypoinsulinemia, hyperglycemia and hyperlipidemia. Stimulation of alpha₁-adrenoceptors by norepinephrine (in the presence of propranolol) in right ventricles resulted in the formation of inositol monophosphate (measured with a radioisotope method) and inositol 1,4,5-trisphosphate (measured with an inositol 1,4,5-trisphosphate protein binding assay kit) in a time- and concentration-dependent manner in both control and diabetic rats. The increase in inositol 1,4,5-trisphosphate levels preceded the increase in the alpha₁-adrenoceptor-mediated positive inotropic effect. Diabetic hearts showed a greater maximum inotropic response to norepinephrine stimulation and also had a higher inositol 1,4,5-trisphosphate levels. However, with the radioisotope method, a decreased inositol monophosphate formation was shown in diabetic hearts compared with controls. Omega-3 fatty acids supplementation (Promega[symbol omitted], 0.5 ml/kg/day) had no significant effect on the changes in norepinephrine-stimulated inositol monophosphate formation in diabetic hearts. In the presence of the cyclooxygenase inhibitor indomethacin or the thromboxane synthetase inhibitor imidazole, the norepinephrine-stimulated positive inotropic effect and inositol 1,4,5-trisphosphate formation were significantly increased in control hearts, but were unaltered in the hearts from diabetics. The addition of the prostacyclin synthetase inhibitor tranylcypromine reduced the norepinephrine-stimulated positive inotropic effect and inositol 1,4,5-trisphosphate formation only in diabetic hearts and had no effect in the controls. While inositol 1,4,5-trisphosphate may be able to mediate only transient inotropic effects produced by alpha₁-adrenoceptor stimulation, diacylglycerol may provoke a sustained positive inotropic effect by activating slow Ca²⁺ channels through stimulation of protein kinase C. Our results showed that the diabetic hearts had a higher protein kinase C activity in the membrane fraction compared with controls and this was accompanied by a decrease in cytosolic protein kinase C activity. The present study suggests that the increases in inositol 1,4,5-trisphosphate levels and the membrane fraction protein kinase C activity may be implicated in the increased inotropic responsiveness to alpha₁-adrenoceptor stimulation in the hearts of the streptozotocin-diabetic rats. The increases in inositol 1,4,5-trisphosphate level and protein kinase C activity could induce Ca²⁺ overload in the diabetic heart which might be involved in the development of diabetic cardiomyopathy. The results from the omega-3 fatty acid study indicate that the changes in cardiac alpha₁-adrenoceptor-mediated inositol phosphates formation cannot contribute to the previously described improved cardiac function of omega-3 fatty acid-treated streptozotocin-diabetic rats. The nature and physiological significance of the enhanced positive inotropic effect and inositol 1,4,5-trisphosphate formation in the control heart with the addition of indomethacin and imidazole is still unclear. The effect of tranylcypromine may indicate the participation of prostaglandins in mediating the enhanced alpha₁-inotropic effect of norepinephrine in the diabetic heart. / Pharmaceutical Sciences, Faculty of / Graduate
72

Biocompatibilidade, perfil de permeação e eficácia anestésica de formulações de articaína associada à nanocápsulas de poli (epsilon-caprolactona) / Biocompatibility, permeation profile and anesthetic efficacy of articaine-loaded poly(epsilon-caprolactone) nanocapsules formulations

Silva, Camila Batista da, 1985- 04 October 2015 (has links)
Orientadores: Maria Cristina Volpato, Michelle Franz-Montan Braga Leite / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-27T10:54:29Z (GMT). No. of bitstreams: 1 Silva_CamilaBatistada_D.pdf: 1409264 bytes, checksum: 65dd976e07e29626f67c3414f2a97230 (MD5) Previous issue date: 2015 / Resumo: Articaína é um anestésico local que apresenta boa difusão após infiltração na maxila e mandíbula e rápida biotransformação, mas está associada a maior incidência de parestesia que a lidocaína. Sistemas de liberação como as nanocápsulas têm sido usados para melhorar a disponibilidade e diminuir a toxicidade de fármacos. Os objetivos deste trabalho foram avaliar uma formulação de articaína em nanocápsulas de poli(?-caprolactona) quanto à toxicidade (viabilidade em queratinócitos humanos), capacidade de permeação (através de epitélio de mucosa de esôfago de porco in vitro) e eficácia anestésica (modelo de dor pós-operatória em ratos). As formulações anestésicas testadas foram: articaína (ATC), articaína com epinefrina 1:200.000 (ATCepi), articaína associada a nanocápsulas de poli(?-caprolactona) (ATCnano), articaína associada a nanocápsulas de poli(?-caprolactona) com epinefrina 1:200.000 (ATCnanoepi), com os respectivos controles. As células foram expostas a várias concentrações das formulações durante 1 h e 24 h para os testes de MTT e microscopia de fluorescência. O estudo de permeação foi realizado em célula de difusão vertical tipo Franz com epitélio de de esôfago de porco, sendo avaliados o fluxo e o coeficiente de permeação das formulações ATC e ATCnano. A eficácia anestésica foi avaliada 24 h após desenvolvimento de hipernocicepção na pata traseira de ratos. Os animais receberam 0,1 mL de cada uma das formulações de articaína ou o respectivo controle lateralmente à ferida. A anestesia foi avaliada com o analgesímetro de von Frey. Os resultados foram avaliados por regressão não-linear (teste MTT), Mann-Whitney (fluxo e coeficiente de permeação) e Log-Rank, ANOVA e teste t LSD (sucesso e duração anestésica) (a=5%). A encapsulação de articaína não alterou o tamanho das nanopartículas e o índice de polidispersão, que se manteve baixo (0,11 ± 0,04). No teste de MTT, em ambos os tempos avaliados, a utilização de aditivos diminuiu a toxicidade da articaína (p<0,0001). No estudo de permeação em epitélio de mucosa, ATCnano apresentou maior fluxo (p=0,0007) e coeficiente de permeação (p=0,0004) que ATC. No modelo de dor pós-operatória em ratos a duração e sucesso da articaína 2% e 4%, associadas à epinefrina foram maiores (p<0,05) que os das demais formulações e não diferiram entre si (p>0,05). Conclui-se que a encapsulação e a adição de epinefrina (isolados ou em associação) diminuem a toxicidade da articaína e a encapsulação aumenta a permeação, sinalizando um possível uso da articaína em anestesia tópica. Entretanto, a encapsulação não melhora a eficácia anestésica da articaína em tecidos inflamados, mesmo com adição de epinefrina. A adição de epinefrina é essencial para o aumento do sucesso e duração da anestesia promovida pela articaína. Pela semelhança na eficácia anestésica, a articaína, associada à epinefrina, poderia ser utilizada em tecidos inflamados na menor concentração testada, 2% / Abstract: Articaine is a local anesthetic thar presents good diffusion after maxillary and mandibular infiltration, and fast biotransformation. However, it is associated to higher paresthesia prevalence than lidocaine. Delivery systems, such as nanocapsules, have been used to improve availability and to reduce toxicity of drugs. The aims of this study were to evaluate an articaine-loaded poli(?-caprolactone) formulation in relation to toxicity (in vitro viability of human keratinocyte cells), in vitro permeation capacity (through the mucosal epithelium of pig esophagus), and anesthetic efficacy (postoperative pain model in rats). The formulations tested were: articaine (ATC), articaine with 1:200,000 epinephrine (ATCepi), articaine loaded-nanocapsules of poly(?-caprolactone) (ATCnano), articaine loaded-nanocapsules of poly(?-caprolactone) with 1:200,000 epinephrine (ATCnanoepi) and the respective controls. HaCaT cells were exposed to formulations at various concentrations for 1 h and 24 h for MTT and fluorescence microscopy tests. Permeation profiles (flux and permeation coefficient) of ATC and ATCnano across pig esophageal epithelium were performed in Franz-type vertical diffusion cells. Anesthetic efficacy was evaluated 24 h after development of hypernociception in the hind paw of rats. The animals received, laterally to the wound, 0.1 mL of articaine or control formulations. Local anesthesia was evaluated with von Frey anesthesiometer. Results were evaluated by non-linear regression analysis (MTT test), Mann-Whitney (flux and permeation coefficient) and Log-Rank, ANOVA and t LSD tests (anesthesia success and duration) (a=5%). Encapsulation of articaine did not change nanoparticles size and polidispersion index, which remained at low levels (0.11 ± 0.04). Encapsulation and epinephrine lowered articaine toxicity (p<0.0001) on HaCaT cells. In the permeation study ATCnano presented higher flux (p=0.0007) and permeation coefficient (p=0.0004) than ATC. In the postoperative pain model in rats 2% and 4% articaine (both associated to epinephrine did not differ (p>0.05) and showed higher anesthesia success and duration (p<0.05) than the other articaine formulations. In conclusion, articaine encapsulation and epinephrine addition (isolated or associated) lower articaine toxicity and the encapsulation increases permeation and could provide a future use of articaine for topical anesthesia. However, encapsulation does not improve articaine anesthetic efficacy in inflamed tissues, even with epinephrine addition. Epinephrine addition to articaine is essential to improve its anesthetic success and duration. Due to the similar anesthetic efficacy, when associated to epinephrine, articaine could be used in inflamed tissues at the lower concentration tested, 2% / Doutorado / Farmacologia, Anestesiologia e Terapeutica / Doutora em Odontologia
73

Avaliação da adrenalina, noradrenalina e cortisol sob a formação do biofilme, produção de ácido e expressão de fatores de virulência pelo Streptococcus mutans / Evaluation of adrenaline, noradrenaline and cortisol on biofilm formation, acid production and expression of virulence factors by Streptococcus mutans

Denise Leda Pedrini 30 March 2012 (has links)
Avaliar o efeito in vitro da adrenalina, noradrenalina e cortisol sobre a formação do biofilme, produção de ácido e expressão de fatores de virulência por S. mutans. Método: Para a formação do biofilme foi realizada uma monocultura de S. mutans (UA159) em discos de hidroxiapatita (HA) associados à adrenalina, noradrenalina e cortisol por cinco dias. Após esse período, foi realizada a contagem bacteriana (ufc/ml) para cada grupo experimental. A avaliação da queda do pH (produção de ácidos) foi realizada a cada 12 horas até o final do experimento (cinco dias). Para a avaliação da expressão de fatores de virulência, RNA total de biofilme maduro (cinco dias) foi extraído, e a análise da expressão de genes relacionados com a virulência do S. mutans (gtfB, gtfC, gtfD, brpA e ldh) foi realizada através de RT-qPCR. Resultados: As catecolaminas (adrenalina e noradrenalina) e também o cortisol aumentaram significativamente a formação de colônias de S. mutans em relação ao grupo controle. Uma queda no valor do pH foi observada nas 12 primeiras horas em todos os grupos. Após este período, os valores se mantiveram praticamente estáveis até o final do experimento (120h), não havendo diferença estatística entre o grupo controle e os grupos testes. Em relação ao efeito das catecolaminas/cortisol sobre a expressão de genes de virulência do S. mutans, não se observou diferença estatística significativa entre os diferentes grupos. Conclusões: Os achados do presente estudo demonstraram que a adrenalina, noradrenalina e cortisol aumentam a formação do biofilme (in vitro), sem alterar o pH (produção de ácidos) e expressão dos genes de virulência avaliados. / To evaluate the in vitro effect of adrenaline, noradrenaline and cortisol on biofilm formation, acid production and expression of virulence factors by S. mutans. Methods: Biofilm formation was performed by a monoculture of S. mutans (UA159) in discs of hydroxyapatite (HA) associated with adrenaline, noradrenaline and cortisol for five days. Further, bacterial count was performed (cfu / ml) for each experimental group. Evaluation of the reduction in pH (acid production) was conducted then every 12 hours until the end of treatment (five days). For evaluation of the virulence factors of mature biofilm, total RNA (five days) was extracted and the analysis of expression of genes related to the virulence of S. mutans (gtfB, gtfC, gtfD, brpA and ldh) was performed by RT-qPCR. Results: Catecholamines (adrenaline and noradrenaline) and cortisol tested in this study significantly increased the formation of colonies of S. mutans in the control group. In all groups (control, adrenaline, noradrenaline and cortisol) the highest reduction in pH was observed during the first 15 minutes, with no statistical difference between the control and test group. PH measurements were performed until the 5th day of the experiment at intervals of 12h. Continuous reduction was observed during the first 12 hours in all groups after this period, the values remained almost stable until the end of the experiment (120h). There was no statistical difference between the control and test groups. Regarding the effect of catecholamine / cortisol on the expression of virulence genes of the S. mutans, there was no statistically significant difference among the groups and the control group. Conclusions: The findings of this study demonstrated that adrenaline, norepinephrine and cortisol increase the formation of biofilm (in vitro), without changing the pH (initial and in biofilm) and expression of genes evaluated.
74

Alpha-1 adrenergic receptors, protein kinase C, and regulation of intracellular pH in cardiac purkinje fibers

Breen, Timothy Edward January 1990 (has links)
This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).
75

Identifying effects of adrenaline and dopamine binding on the beta2-adrenergic receptor structure and function using machine learning

Gunnarsson, Joar, Bergner, Leon January 2023 (has links)
The beta2-adrenergic receptor is a G-protein coupled receptor, involved in several physiological processes, which enables signaling through the cell membrane. To study the effect of dopamine and adrenaline binding on the receptor structure and function, we used machine learning methods applied to data from molecular dynamics simulations. We found that the three machine learning methods Random Forest, Kullback-Leibler divergence, and Principal Component Analysis generated results that correspond to previous studies. When comparing the active state of the receptor with or without a ligand bound, we found that residues around Ser203 and Asn301 of the orthosteric binding pocket and residues around Ala91 of the TM2 differed. When instead comparing the active state of the receptor with adrenaline or dopamine bound, we found that residues around Thr68 differed. Additionally, we also found that adrenaline and dopamine cause different structural changes in the intracellular parts of TM5 and TM6. These findings indicate ligand-specific effects on the receptor, providing potentially useful information for the understanding of the interaction of adrenaline and dopamine with the beta2-adrenergic receptor.
76

Adrenal chromaffin cell function in high-altitude deer mice (Peromyscus maniculatus)

Pranckevicius, Nicole 11 1900 (has links)
The deer mouse (Peromyscus maniculatus) inhabits a broad altitudinal range from sea level to over 4300m, where they experience continuous hypoxia. Typically hypoxia activates the sympathetic nervous system; however this could become maladaptive in high-altitude residents if it is maintained over chronic periods. We hypothesized that high-altitude deer mice might have altered the physiology of adrenaomedullary chromaffin cells (AMC) in the adrenal gland to avoid chronic activation of the sympathetic response. Highland mice had lower plasma adrenaline levels compared to lowland populations of Peromyscus mice, both before and after acclimation to hypobaric hypoxia. This did not correspond to any apparent changes in AMC Ca2+-signalling dynamics. Instead a profound blunting of catecholamine storage was found in highland AMCs that appeared to underlie the reduction in adrenaline release / Thesis / Master of Science (MSc)
77

Mecanismos celulares ativados por agonistas adrenérgicos em aorta de ratos hipertensos renais com disfusão endotelial / Cellular mechanisms activated by adrenergic agonists in the aorta of renal hypertensive rats with endothelial dysfunction

Bocalon, Ana Carolina Campos Cotrim 30 September 2014 (has links)
O sistema nervoso simpático (SNS) desempenha importante papel sobre o controle da pressão arterial assim como o endotélio, pela liberação de fatores de relaxamento e contração que atuam sobre a modulação do tônus vascular. A hipertensão renovascular (2R-1C) está associada à elevada produção de espécies reativas de oxigênio, hiperatividade do SNS e disfunção endotelial. A hipótese deste trabalho é de que os agonistas adrenérgicos noradrenalina (NOR) e adrenalina (ADR), catecolaminas endógenas, promovam efeito anti-contrátil devido à ativação da eNOS em aorta de ratos 2R-1C. Este estudo teve por objetivo investigar se a ativação de adrenoceptores (AR) com NOR ou ADR leva à maior ativação da eNOS em aortas de ratos 2R-1C do que em 2R e os mecanismos relacionados. Realizamos curvas concentração-efeito para NOR ou ADR, em aortas com ou sem endotélio de ratos 2R e 2R-1C em ausência (controle) ou presença dos antagonistas ?-AR (propranolol), ?2-AR (ioimbina), e inibidor não seletivo da NOS (L-NAME). Por western blot, verificamos a fosforilação do resíduo de ativação da enzima eNOS, Serina1177 (Ser1177), via ativação de ?-AR ou ?-AR, pela NOR ou ADR em aortas com endotélio, de ratos 2R e 2R-1C e se a via PI3K/AKT e o H2O2 estariam envolvidos nesse processo. Avaliamos a produção de NO pelas células endoteliais isoladas de ratos 2R e 2R-1C, por citometria de fluxo. Realizamos a dosagem de NOR e ADR plasmática e tecidual (adrenais) por meio de HPLC. Nos estudos de reatividade vascular avaliamos a potência (pD2) e eficácia (Emax) dos agonistas em induzir contração. O Emax da NOR foi menor na contração de aorta de ratos 2R-1C comparada a 2R, provavelmente devido à maior atividade da eNOS evidenciada pelo efeito do L-NAME em aorta de 2R-1C. A particularidade mais significativa da resposta da NOR é de que em aorta de ratos 2R-1C, a NOR promove a maior fosforilação de Ser1177 via ?-AR, e esta envolve a participação da via PI3K/AKT e do H2O2, não havendo alteração dos níveis plasmáticos e tecidual de NOR entre 2R e 2R-1C. O estímulo com ADR, em aorta de 2R-1C, promoveu aumento da atividade da eNOS, certificada pelo efeito do L-NAME, que pode contribuir para o menor Emax da ADR em 2R-1C do que em 2R. Entretanto, a ADR promoveu maior fosforilação de Ser1177 via ?-AR, em aorta de ratos 2R-1C, e esta não envolve participação da via PI3K/AKT e do H2O2. Os níveis teciduais de ADR foram semelhantes entre 2R e 2R- 1C, mas a concentração plasmática de ADR foi menor em 2R-1C do que em 2R. Não houve diferença na produção de NO pelas células endoteliais entre 2R e 2R-1C. Os resultados obtidos sugerem que a ativação de ?-AR com NOR envolve participação de H2O2 e da via PI3K/AKT para maior ativação da eNOS em aortas de ratos 2R-1C, mecanismo que pode contribuir para o menor Emax da NOR em aorta de 2R-1C. A ADR ao ativar ?-AR leva à maior ativação da eNOS, porém sem participação efetiva de H2O2 e da via PI3K/AKT em aortas de ratos 2R-1C. / The sympathetic nervous system (SNS) plays important role on the arterial pressure control as well the vascular endothelium by relaxing and contractile factors release that modulates the vascular tone. The renovascular hypertension (2K-1C) is related to the increased production of oxygen reactive species, SNS hyperactivity and endothelium dysfunction. The hypothesis of this work is that the adrenoceptor (AR) agonists noradrenaline (NOR) and adrenaline (ADR), the endogenous catecholamine promote anti-contractile effect due to eNOS activation in 2K-1C rat aorta. This study aimed to investigate if AR activation by NOR or ADR leads to the increased activation of eNOS in 2K-1C rat aorta, and the mechanisms activated by these agonists. Concentration-effect curves were constructed for NOR or ADR, in intactendothelium or denuded aortas isolated from 2K-1C and 2K rats in the absence (control) or in the presence of the AR antagonists propranolol (?-AR) or yohimbine (?2-AR), or the non-selective NOS inhibitor, L-NAME. By using western blot, we have veryfied the the effects of activation of ?-AR ou ?-AR and the phosphorylation of NOS activation site Serine1177 (Ser1177) by NOR or ADR in intact endothelium aorta from 2K and 2K-1C and also whether the PI3K/AKT pathway and hydrogen peroxide (H2O2) are related to this phosphorylation. We evaluated by flow cytometry the NO production in the isolated endotelial cells from 2K and 2K-1C. Plasma and tissue (adrenal) levels of NOR and ADR were measured by HPLC. In the vascular reactivity studies, we evaluated the potency (pD2) and efficacy (Emax) of the agonists in inducing contraction. The Emax induced by NOR was lower in 2K-1C than in 2K rat probably due to the higher activity of eNOS as shown by the effect of L-NAME. The most interesting finding was in 2K-1C aorta that NOR increases the Ser1177 phosphorylation via ?-AR activation that involves the signaling trough PI3K/AKT and H2O2. There is no differences in NOR at the plasma and tissue levels between 2K-1C and 2K. ADR activates more eNOS in 2K-1C rat aorta as shown by the effect of LNAME. It could contribute to the lower Emax of ADR in 2K-1C than in 2K. However, ADR increased Ser1177 phosphorylation via ?-AR activation in 2K-1C rat aorta, which does not involve PI3K/AKT and H2O2 pathway. The tissue levels of ADR were not different between 2K-1C and 2K, but the plasma concentration of ADR was lower in 2K-1C than in 2K. There was no difference in the NO production in the endothelial cells from 2K-1C and 2K. Taken together, our results suggest that ?-AR activation by NOR involves H2O2 and PI3K/AKT that activates eNOS in 2K-1C rat aorta that could contribute to the lower contractile effect induced by NOR in 2K-1C. ?-AR activation by ADR leads to the eNOS activation without activation of H2O2 and PI3K/AKT pathway in 2K-1C rat aorta.
78

Mecanismos celulares ativados por agonistas adrenérgicos em aorta de ratos hipertensos renais com disfusão endotelial / Cellular mechanisms activated by adrenergic agonists in the aorta of renal hypertensive rats with endothelial dysfunction

Ana Carolina Campos Cotrim Bocalon 30 September 2014 (has links)
O sistema nervoso simpático (SNS) desempenha importante papel sobre o controle da pressão arterial assim como o endotélio, pela liberação de fatores de relaxamento e contração que atuam sobre a modulação do tônus vascular. A hipertensão renovascular (2R-1C) está associada à elevada produção de espécies reativas de oxigênio, hiperatividade do SNS e disfunção endotelial. A hipótese deste trabalho é de que os agonistas adrenérgicos noradrenalina (NOR) e adrenalina (ADR), catecolaminas endógenas, promovam efeito anti-contrátil devido à ativação da eNOS em aorta de ratos 2R-1C. Este estudo teve por objetivo investigar se a ativação de adrenoceptores (AR) com NOR ou ADR leva à maior ativação da eNOS em aortas de ratos 2R-1C do que em 2R e os mecanismos relacionados. Realizamos curvas concentração-efeito para NOR ou ADR, em aortas com ou sem endotélio de ratos 2R e 2R-1C em ausência (controle) ou presença dos antagonistas ?-AR (propranolol), ?2-AR (ioimbina), e inibidor não seletivo da NOS (L-NAME). Por western blot, verificamos a fosforilação do resíduo de ativação da enzima eNOS, Serina1177 (Ser1177), via ativação de ?-AR ou ?-AR, pela NOR ou ADR em aortas com endotélio, de ratos 2R e 2R-1C e se a via PI3K/AKT e o H2O2 estariam envolvidos nesse processo. Avaliamos a produção de NO pelas células endoteliais isoladas de ratos 2R e 2R-1C, por citometria de fluxo. Realizamos a dosagem de NOR e ADR plasmática e tecidual (adrenais) por meio de HPLC. Nos estudos de reatividade vascular avaliamos a potência (pD2) e eficácia (Emax) dos agonistas em induzir contração. O Emax da NOR foi menor na contração de aorta de ratos 2R-1C comparada a 2R, provavelmente devido à maior atividade da eNOS evidenciada pelo efeito do L-NAME em aorta de 2R-1C. A particularidade mais significativa da resposta da NOR é de que em aorta de ratos 2R-1C, a NOR promove a maior fosforilação de Ser1177 via ?-AR, e esta envolve a participação da via PI3K/AKT e do H2O2, não havendo alteração dos níveis plasmáticos e tecidual de NOR entre 2R e 2R-1C. O estímulo com ADR, em aorta de 2R-1C, promoveu aumento da atividade da eNOS, certificada pelo efeito do L-NAME, que pode contribuir para o menor Emax da ADR em 2R-1C do que em 2R. Entretanto, a ADR promoveu maior fosforilação de Ser1177 via ?-AR, em aorta de ratos 2R-1C, e esta não envolve participação da via PI3K/AKT e do H2O2. Os níveis teciduais de ADR foram semelhantes entre 2R e 2R- 1C, mas a concentração plasmática de ADR foi menor em 2R-1C do que em 2R. Não houve diferença na produção de NO pelas células endoteliais entre 2R e 2R-1C. Os resultados obtidos sugerem que a ativação de ?-AR com NOR envolve participação de H2O2 e da via PI3K/AKT para maior ativação da eNOS em aortas de ratos 2R-1C, mecanismo que pode contribuir para o menor Emax da NOR em aorta de 2R-1C. A ADR ao ativar ?-AR leva à maior ativação da eNOS, porém sem participação efetiva de H2O2 e da via PI3K/AKT em aortas de ratos 2R-1C. / The sympathetic nervous system (SNS) plays important role on the arterial pressure control as well the vascular endothelium by relaxing and contractile factors release that modulates the vascular tone. The renovascular hypertension (2K-1C) is related to the increased production of oxygen reactive species, SNS hyperactivity and endothelium dysfunction. The hypothesis of this work is that the adrenoceptor (AR) agonists noradrenaline (NOR) and adrenaline (ADR), the endogenous catecholamine promote anti-contractile effect due to eNOS activation in 2K-1C rat aorta. This study aimed to investigate if AR activation by NOR or ADR leads to the increased activation of eNOS in 2K-1C rat aorta, and the mechanisms activated by these agonists. Concentration-effect curves were constructed for NOR or ADR, in intactendothelium or denuded aortas isolated from 2K-1C and 2K rats in the absence (control) or in the presence of the AR antagonists propranolol (?-AR) or yohimbine (?2-AR), or the non-selective NOS inhibitor, L-NAME. By using western blot, we have veryfied the the effects of activation of ?-AR ou ?-AR and the phosphorylation of NOS activation site Serine1177 (Ser1177) by NOR or ADR in intact endothelium aorta from 2K and 2K-1C and also whether the PI3K/AKT pathway and hydrogen peroxide (H2O2) are related to this phosphorylation. We evaluated by flow cytometry the NO production in the isolated endotelial cells from 2K and 2K-1C. Plasma and tissue (adrenal) levels of NOR and ADR were measured by HPLC. In the vascular reactivity studies, we evaluated the potency (pD2) and efficacy (Emax) of the agonists in inducing contraction. The Emax induced by NOR was lower in 2K-1C than in 2K rat probably due to the higher activity of eNOS as shown by the effect of L-NAME. The most interesting finding was in 2K-1C aorta that NOR increases the Ser1177 phosphorylation via ?-AR activation that involves the signaling trough PI3K/AKT and H2O2. There is no differences in NOR at the plasma and tissue levels between 2K-1C and 2K. ADR activates more eNOS in 2K-1C rat aorta as shown by the effect of LNAME. It could contribute to the lower Emax of ADR in 2K-1C than in 2K. However, ADR increased Ser1177 phosphorylation via ?-AR activation in 2K-1C rat aorta, which does not involve PI3K/AKT and H2O2 pathway. The tissue levels of ADR were not different between 2K-1C and 2K, but the plasma concentration of ADR was lower in 2K-1C than in 2K. There was no difference in the NO production in the endothelial cells from 2K-1C and 2K. Taken together, our results suggest that ?-AR activation by NOR involves H2O2 and PI3K/AKT that activates eNOS in 2K-1C rat aorta that could contribute to the lower contractile effect induced by NOR in 2K-1C. ?-AR activation by ADR leads to the eNOS activation without activation of H2O2 and PI3K/AKT pathway in 2K-1C rat aorta.
79

Mathematical modeling of adrenaline-induced adiponectin secretion in white adipocytes

Simonsson, Christian January 2018 (has links)
There is an ongoing worldwide obesity epidemic. As a consequence, prevalence of obesity- related diseases and conditions are rapidly increasing. One of these related conditions is type 2 diabetes (T2D), which alone caused 1.5 million deaths in 2012. Thus, it is of upmost importance to develop a more complete understanding of these interrelated diseases. At the heart of all these diseases lies the adipose tissue. This tissue is a major endocrine organ, and one of the key secreted cytokines is adiponectin. Adiponectin interplays with the complex insulin signaling network, and adiponectin levels are inversely related with increased adiposity. The presence of these complex dependencies argues for the usage of mathematical modelling. In the work of Brännmark et al, a model of short-term adiponectin release has been validated. However, this model did not include adrenergic signaling, which is the canonical pathway for in situ regulation of adiponectin secretion. To fill this gap, herein, a mechanistic model describing adrenaline-induced short-term adiponectin exocytosis in white adipocytes has been constructed. The newly constructed model is capable of describing experimental data depicting adiponectin release due to adrenergic stimulation as well as data for different mediator combinations. By implementing adrenergic receptor components, the transition to a more physiological model has been initiated. By finding the smallest possible model capable of describing data, one can argue that the model depicts, to some degree, the fundamental mechanisms for short-term adiponectin secretion. Thus, this work has contributed to solidifying the framework of the mechanisms behind short-term adiponectin secretion from white adipocytes. The result of the model work upholds the role of adrenergic signaling as a central regulatory mechanism for adiponectin release. The constructed model could be used as a fundament for creating a model describing adiponectin release under diabetic conditions.
80

Uppvisar standarddos vasopressin alternativt högdos adrenalin överlevnadsfördel hos vuxna patienter med hjärtstillestånd jämfört med standarddos adrenalin? / Does standard dose vasopressin alternatively high dose adrenaline show survival advantage in adult patients suffering from cardiac arrest compared to standard dose adrenaline?

Carlander, Robin January 2018 (has links)
Hjärtstillestånd är ett tillstånd då hjärtat förlorat förmågan att pumpa ut blod i kroppen vilket leder till cerebral och koronar ischemi. Hjärtstillestånd definieras som plötslig och ihållande medvetslöshet med pulslöshet och andningsstillestånd eller agonal andning. Vanliga symtom som kan uppstå en timme före hjärtstilleståndet är yrsel, trötthet, bröstsmärtor och andningssvårigheter. Behandlingen vid hjärtstillestånd i Sverige utgörs av ”basic” och ”advanced cardiac life support”. De viktigaste åtgärderna innefattar hjärt-lung-räddning, defibillering och läkemedelsadministrering. Förstahandsläkemedlet är standarddos adrenalin baserat på den vasokontraherande och därmed blodtryckshöjande effekten. Syftet med arbetet är att utvärdera effekten av standarddos vasopressin alternativt högdos adrenalin jämfört med standarddos adrenalin på vuxna med hjärtstillestånd. Arbetet är en litteraturstudie där sju studier om effekten av standarddos adrenalin jämfört med standarddos vasopressin alternativt högdos adrenalin vid hjärtstillestånd hos vuxna har analyserats. Studierna hämtades från databasen Pubmed. De patienter som behandlades med standarddos vasopressin istället för den första eller andra standarddosen adrenalin hade bättre överlevnad till sjukhusinläggning (31,6% jämfört med 26,0%, p &lt;0,01). De patienter som behandlades med högdos adrenalin istället för standarddos adrenalin hade bättre överlevnad till sjukhusinläggning (26,1% jämfört med 23,1%, p &lt;0,05). Ingen överlevnadsfördel till sjukhusutskrivning fanns för varken standarddos vasopressin eller högdos adrenalin. Dock behövs fler studier med fler patienter för att verifiera resultaten i denna litteraturstudie. Det vore även intressant med studier som fokuserar på de enskilda hjärtstilleståndsrytmerna. Dessutom behövs mer forskning om de potentiellt negativa effekterna på hjärtat och hjärnan som högdos adrenalin kan ha. Orsaken till den dåliga överlevnaden till sjukhusutskrivning oavsett vasopressorisk behandling behöver utredas. / Cardiac arrest is a state when the heart has lost the ability to pump blood to the body which causes cerebral and coronary ischemia. Cardiac arrest is defined as sudden and sustained unconsciousness with pulselessness and suspension of breathing or agonal breathing. Common symptoms that can arise one hour before a cardiac arrest includes dizziness, tiredness, chest pain and breathing difficulties. The treatment for cardiac arrest in Sweden includes basic and advanced cardiac life support. The most important measures are cardiopulmonary resuscitation, defibrillation and drug administration. The drug of choice is standard dose adrenaline based on its vasoconstricting and thus blood pressure raising effect. The aim of this study was to evaluate the effect of standard dose vasopressin alternatively high dose adrenaline compared to standard dose adrenaline in adults with cardiac arrest. This study is a literature review where seven studies on the effect of standard dose adrenaline compared to standard dose vasopressin alternatively high dose adrenaline on cardiac arrest in adults have been analyzed. The studies were found in the database Pubmed. Four studies evaluate the effect on survival by standard dose vasopressin compared to standard dose adrenaline. Three studies evaluate the effect on survival by high dose adrenaline compared to standard dose adrenaline. Patients that were treated with standard dose vasopressin instead of the first or second standard dose adrenaline had better survival to hospital admission (31,6% compared to 26,0%, p &lt;0,01). Patients that were treated with high dose adrenaline instead of standard dose adrenaline had better survival to hospital admission (26,1% compared to 23,1%, p &lt;0,05). There were no effects on survival to hospital discharge for either standard dose vasopressin or high dose adrenaline. More studies are needed though with more patients to verify the results of this literature review. It would also be interesting with studies that focus on the different cardiac arrest rhytms. More research is needed about the potential negative effects on the heart and brain caused by high dose adrenaline. The reason for the bad results regarding survival to hospital discharge regardless of vasopressive treatment needs to be evaluated.

Page generated in 0.1108 seconds