Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 5 uppsatser.

Lic.-avh. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 2 uppsatser.

Thesis (M.Sc.) - Carleton University, 2003. / Includes bibliographical references (p. 81-87). Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 108-129).

Thesis (Ph. D.)--University of Oregon, 2006. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 88-100). Also available for download via the World Wide Web; free to University of Oregon users.

The upregulation of the inducible nitric oxide synthase (iNOS) and nitric oxide (NO) production have been implicated in inflammatory pathologies. Although research has revealed that glucocorticoids (GCs) such as dexamethasone and hydrocortisone inhibit iNOS expression and NO production, it remains unclear how these compounds attenuate iNOS expression and function. In response, this thesis has compared the effects of nonselective GCs (i.e., dexamethasone and hydrocortisone) with a selective GC namely, fluticasone propionate (fluticasone) to identify the precise GC actions that regulate the iNOS pathway. Additional investigations were performed to distinguish the GC and non-GC actions using receptor antagonists. Since the effects of GCs on upstream signalling pathways remain vague, further studies were conducted to investigate whether fluticasone regulates the p38 mitogen-activated protein kinases or protein kinase B (Akt) pathways, both of which have been reported to be critical for the induction of iNOS. All experiments were conducted using primary cultures of rat aortic smooth muscle cells (RASMCs). The cells were activated with bacterial LPS (100 μg/mL) and interferon-gamma (IFN-γ, 100 U/mL) to induce iNOS and NO. Nitrite levels in cellular supernatants were quantified by the Griess assay, and expressions of iNOS, phospho-p38 (P-p38), and phospho-Akt (P-Akt) were investigated by western blotting. Dexamethasone (0.1-10.0 μM) inhibited iNOS expression and NO production in a concentration dependent manner that was significant at higher concentrations (0.3-10.0 μM). Hydrocortisone (0.01-10.0 μM) also inhibited iNOS expression and NO production in a concentration dependent manner which was significant at the higher concentrations (0.1-10.0 μM). By contrast, fluticasone (0.1 nM-3.0 μM) inhibited NO production and iNOS expression only partially (~50%), and the effects were significant at 1 nM-3 μM. RU-486 (10 μM), a GC receptor (GCR) blocker, was able to reverse the inhibitions caused by dexamethasone, hydrocortisone, and fluticasone, though eplerenone (0.1-10.0 μM), the mineralocortocoid receptor blocker, had no effect. Fluticasone also inhibited the phosphorylation of p38 and Akt in activated RASMCs. The inhibitions were reversed upon incubation with RU-486 (10 μM) for 1 h prior to the addition of fluticasone. The partial inhibition of iNOS and NO by fluticasone suggests that the actions of dexamethasone and hydrocortisone were not restricted solely to GCR and that other receptors or pathways, if not both, might regulate iNOS and NO in RASMCs. In conclusion, the nonselective GCs (i.e., dexamethasone and hydrocortisone) showed a full inhibition of iNOS expression and function, whereas fluticasone only partially inhibited both processes. The inhibitions were reversed by RU-486, but not eplerenone, which strongly suggests a GC-mediated response to all three compounds investigated. Regarding fluticasone, mechanistic studies revealed that the GC can regulate key signalling pathways associated with the induction of iNOS. More specifically, fluticasone reduced the phosphorylation of p38 and Akt, thereby suggesting that its actions can be mediated by suppressing these kinase pathways, which are widely reported to critically regulate iNOS expression and function.

Made available in DSpace on 2014-06-11T19:33:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-12Bitstream added on 2014-06-13T21:06:12Z : No. of bitstreams: 1 oliveira_sr_dr_araca.pdf: 4808815 bytes, checksum: 6fc8deeffcd2c27c59c5d08cd94ab969 (MD5) / As modalidades terapêuticas que envolvem implantes dentais têm se expandido gradativamente, sendo implantados em uma variedade de estruturas ósseas. Dessa forma, o propósito do presente trabalho foi estudar a influência de corticóides no processo inicial de osseointegração de implantes de titânio instalados em maxilas de ratos. Foram utilizados implantes de titânio c.p., grau II, cônico de 1,4mm de diâmetro e 2,7mm de comprimento, com superfície tratada. Trinta e oito ratos wistar tiveram seus primeiros molares superiores esquerdo e direito extraídos. Após 30 dias de reparo alveolar, dois animais foram sacrificados para confirmar o fim desse processo. Os demais animais tiveram os implantes instalados bilateralmente e foram divididos randomicamente em três grupos: Controle (Ctr/n=12) que não receberam nenhum tipo de tratamento; Placebo (Pl/n=12) e Tratado (Tra/n=12), que receberam injeções diárias de 1 ml de solução salina e corticosterona na dosagem de 5mg/kg, respectivamente. Trinta dias após a implantação, todos os animais foram eutanasiados e tiveram a concentração plasmática do corticóide mensurada: Ctr (101,31 ± 26,7 ng/ml), Pla (95,22 ± 25,36 ng/ml) e Tra (281,37 ± 64,72 ng/ml); e o contato osso-implante determinado: Ctr (96,67%), Pla (82,22%) e Tra (15,73%), nos quais o grupo Tra apresentou-se estatisticamente diferente dos demais grupos (p<0,05). Assim, diante da metodologia empregada, foram evidenciadas menor formação óssea e conseqüente redução da área de tecido ósseo neo-formado na interface osso-implante. / The therapeutic modalities which involves dental implants has been gradually expanded, being implanted in a variety of bone structures. In this way, the aim of the present work was to study the corticoid influence at the initial process of bone integration of titanium implants installed in rat jaws. It were used titanium implants c.p.; grade II, conic with 1,4mm diameter and 2,7mm length, with treated surface. Thirty eight wistar rats had their first upper left and right molars extracted. After 30 days of alveolar repair, two animals were sacrificed to confirm the end of this process. The others had their implants installed bilaterally and they were splited randomly in three groups: Control (Ctr/n=12) which did not receive any kind of treatment; Placebo (Pla/n=12) and Treated (Tre/n=12) which received 1ml daily shots of salt solution and corticosterone at a dosage of 5mg/Kg, respectively. Thirty days after the implantation, all the animals were euthanasiated and the plasmatic concentration of corticoid was measured: Ctr (101,31 ± 26,7 ng/ml), Pla (95,22 ± 25,36 ng/ml) and Tre (281,37 ± 64,72 ng/ml); and the bone implant contact was determined: Ctr (96,67%), Pla (82,22%) and Tre (15,73%), in which the Tre group presented statistically different from the other groups (p<0,05). Thus, front the employed methodology it was shown lesser bone formation and consequent reduction of the bone tissue area neo-formed at bone-implant interface.

Made available in DSpace on 2016-06-02T19:23:00Z (GMT). No. of bitstreams: 1 6274.pdf: 1177315 bytes, checksum: 32dbfa4156c89cf69608584f37577279 (MD5) Previous issue date: 2014-03-28 / Universidade Federal de Minas Gerais / Dexamethasone (DEX) is widely used to treat inflammation and allergies, but its chronic use determines several side effects such as hyperglycemia, muscle atrophy and hypertension (H). The renin-angiotensin system (RAS) is an important regulator of blood pressure (BP) and its increased activity may be one possible mechanism responsible to increase BP induced by DEX. On the other hand, low to moderate aerobic exercise has been recommended for treatment of hypertension and its effects on RAS have been demonstrated. We recently demonstrated that physical preconditioning attenuates H induced by DEX, however little is known about the mechanisms responsible for this response. Therefore, the aim of this study was to investigate whether RAS participated in the BP increase induced by DEX and BP reduction induced by aerobic preconditioning was associated with an alteration of RAS components. Rats were subjected to an aerobic exercise protocol on the treadmill or kept sedentary for 8 weeks. Additionally, animals were treated with DEX (1.0mg/kg of body weight per day i.p. for 10 days) and treated or not with losartan. Groups were: sedentary control (SC), DEX sedentary (SD), trained control (TC) and trained DEX (TD), sedentary losartan (SCL), sedentary DEX and losartan (SDL), trained losartan (TCL) and trained DEX and losartan (TDL). Body weight (BW), fasting glucose and resting blood pressure were analyzed. After euthanasia, the tibialis anterior (TA), soleus (SOL), flexor hallucis longus (FHL) and left ventricle (LV) were collected for evaluation of gene expression and protein levels of RAS components. Treatment with DEX caused decrease of BW and TA and FHL muscle weight (MW), and determined an increase in fasting glucose (+132%) and BP (16%). Losartan treated animals did not present BP attenuation after DEX treatment. Physical training did not prevent BW or MW loss, however it attenuated the increase in fasting glucose (60%) and BP (7%). Training increased ACE and AT1 mRNA which were further reduced in the LV muscle of TD group. Also, training increased 31% (TC) and 47% (TD) the protein levels of AGT. In the TA muscle, DEX increased by 270% the AT1 mRNA and by 175 % the MAS mRNA. TD group showed increases on AT2 mRNA (+142%) and MAS (+78%). DEX also reduced AT2 (-5%) protein levels and training did not prevent this reduction (- 13%, TD). In the SOL muscle DEX increased 87% AGT gene expression and trained rats presented an increase of AT1 (+32%) and ACE (+50%) mRNA. TD group presented increases of ACE (+53%), AT1 (+51%) and AGT (+155%) gene expression and no changes on protein levels were observed. In FHL muscle DEX determined protein level reduction of vasodilators RAS components (-20 % AT2; -33% ACE2 and - 36% MAS), although the TC group also presented a reduction on ACE2 (-16%) and MAS (-27%). TD group presented an increase of 47% on ACE2 protein level. Taken together these and the no effect of losartan on BP, we can suggest that RAS is not the main mechanism involved in this model of Hypertension induced by DEX. / A Dexametasona (DEX) é amplamente utilizada no tratamento de inflamações e alergias, porém seu uso crônico determina vários efeitos colaterais como hiperglicemia, atrofia muscular e hipertensão (HA). O sistema renina-angiotensina (SRA) é um importante regulador da pressão arterial e sua maior atividade pode ser um dos possíveis mecanismos responsáveis pelo aumento da pressão arterial (PA) induzida pela DEX. Por outro lado, o exercício físico aeróbio, de baixa e moderada intensidade, tem sido recomendado como coadjuvante no tratamento da HA e seus benefícios sobre as alterações do SRA têm sido demonstrados. Observamos recentemente que o pré-condicionamento físico atenua a HA induzida pela DEX, no entanto pouco se sabe sobre os mecanismos responsáveis por esta resposta. Portanto, o objetivo deste trabalho foi investigar se o SRA participava do aumento da PA induzido pela DEX e se a redução da PA induzida pelo pré-condicionamento aeróbio estava associada com a alteração dos componentes do SRA. Ratos Wistar foram submetidos a um protocolo de exercício físico aeróbio na esteira ou mantidos sedentários por 8 semanas. Além disso, os animais foram tratados ou não com DEX (1,0 mg/kg de peso corporal, por dia, i.p, por 10 dias) e tratados ou não com losartan, compondo assim 8 grupos, a saber: sedentário controle (SC), sedentário DEX (SD), treinado controle (TC) e treinado DEX (TD), sedentário losartan (SCL), sedentário DEX e losartan (SDL), treinado losartan (TCL) e treinado DEX e losartan (TDL). Foram analisados peso corporal (PC), glicemia de jejum e pressão arterial de repouso. Após a eutanásia, os músculos tibial anterior (TA), sóleo (SOL), flexor longo do hálux (FHL) e ventrículo esquerdo (VE) foram coletados para a avaliação da expressão gênica e proteica dos componentes do SRA. O tratamento com DEX determinou redução do PC e do peso muscular (PM) do TA e FHL, além de aumento da glicemia de jejum (+132%) e PA (16%). Os animais tratados com losartan não apresentaram atenuação do aumento da PA após tratamento com DEX. O treinamento físico não preveniu a perda do PC e PM, no entanto atenuou o aumento da glicemia de jejum (60%) e da PA (7%). No VE observamos que o treinamento aumentou o mRNA de AT1 e ECA que foram reduzidos no grupo TD e aumentou em 31% (TC) e 47% (TD) os níveis proteicos do AGT. No músculo TA, a DEX aumentou o mRNA em 270% do AT1 e 175% do MAS, por outro lado o grupo TD apresentou aumento do mRNA do AT2 (+142%) e do MAS (+78%). A DEX determinou redução dos níveis proteicos do AT2 (- 5%) e o treinamento não preveniu esta redução (-13%, TD). No músculo SOL, a DEX aumentou o mRNA em 87% do AGT. Os animais treinados apresentaram aumento de mRNA do AT1 (+32%) e ECA (+50%) e no grupo TD houve aumento de ECA (+53%), AT1 (+51%) e AGT (+155%), sem qualquer alteração nas proteínas. No músculo FHL a DEX determinou redução das proteínas dos componentes vasodilatadores do SRA (- 20% AT2; -33% ECA2 e -36% MAS), apesar do grupo TC também ter uma redução de ECA2 (-16%) e MAS (-27%), por outro lado o grupo TD aumentou em 47% as quantidades de ECA2. Estes resultados, associados com a não atenuação da PA após tratamento com losartan, sugerem que o SRA não seja o principal mecanismo envolvido no aumento da PA neste modelo induzido pela DEX e provavelmente outros mecanismos estejam contribuindo para este aumento.

Made available in DSpace on 2016-06-02T19:23:01Z (GMT). No. of bitstreams: 1 6295.pdf: 4882645 bytes, checksum: 753ebcc5b034e8345c6f3057edbdb562 (MD5) Previous issue date: 2014-03-28 / Universidade Federal de Minas Gerais / The use of glucocorticoids as treatment for allergic and inflammatory conditions has become commom nowadays, although, chronically it can causes many side effects such as peripheral insulin resistance, hyperglycemia and hyperinsulinemia, hypertension, dyslipidemia, body weight loss and muscle atrophy. On the other hand, resistance training (RT) has been recommended as non-pharmacological treatment for some pathological conditions, however little is known about its effects on muscle atrophy induced by chronic treatment with dexamethasone (DEX). The aim of this study was to verify the preventive effect of RT (80% of maximal carrying capacity) on DEX-induced muscle atrophy as well as the responsible mechanisms for this response. Forty-three wistar rats (200-250g) were allocated into four groups: sedentary control (SC), sedentary treated with DEX (SD), trained control (TC) and trained treated with DEX (TD). After a familiarization period on the ladder, a maximal voluntary carrying capacity test (MVCC) was performed to determinate the training intensity and the rats underwent or RT (80% MCCT, 4 days/week, 70 days) or remained sedentary. The MVCC was performed in the beginning, after 4 weeks, before and after the DEX treatment. Through the last ten days, the animals received DEX (0.5 mg/kg/day, i.p.) or saline solution. After 24 hours of the last training session, the animals were euthanized and the flexor hallucis longus (FHL), tibialis anterior (TA) and soleus (SOL) muscles were collected and weighted for further analysis of mTOR, p70S6K, FOXO3a, Atrogin-1 and MuRF-1 protein levels. The results were presented as mean ± SEM, &#945;<0.05. DEX treatment evoked adrenal gland atrophy (-47%), body weight loss (-21%) and food intake reduction (-28%). The RT increased MVCC of trained animals (+215%). Also, DEX treatment reduced FHL and TA muscles mass (-19.6% e -17.7%, respectively), which was associated with the MuRF-1 protein level increase (+37% e +45,5%, respectively). We did not observe any alterations in mTOR, p70S6K, FOXO3a and Atrogin-1 protein levels after DEX treatment. RT was be able to attenuate FHL muscle atrophy due to blockade of MuRF-1 increase (-3.5%). In addition, it did increase mTOR (+63% for TC e TD) e p70S6K (+46% and +49% for TC e TD, respectively) protein levels in FHL muscle. FOXO3a and Atrogin-1 protein levels were not altered by RT. SOL muscle was not affected by neither treatment nor training. Therefore, these results allow us to suggest that DEX-induced muscle atrophy observed in the FHL and TA muscles can be associated with increases in MuRF-1 protein level. RT-induced attenuation of FHL muscle atrophy involved increases in mTOR and p70S6K protein levels associated with maintenance of MuRF-1 protein levels. / O uso de glicocorticoides como tratamento de quadros inflamatórios e alérgicos tem sido uma constante na atualidade, embora, cronicamente provoque vários efeitos colaterais como resistência periférica à insulina, hiperglicemia e hiperinsulinemia, hipertensão, dislipidemia, perda de peso corporal e atrofia muscular. Por outro lado o treinamento resistido (TR) tem sido recomendado como tratamento não farmacológico em alguns estados patológicos, embora pouco se conheça sobre seus efeitos sobre a atrofia muscular induzida pelo tratamento crônico com dexametasona (DEX). O objetivo principal deste trabalho foi verificar o efeito preventivo do TR a 80% do carregamento máximo sobre a atrofia muscular induzida pela DEX, bem como os mecanismos responsáveis por esta resposta. Foram utilizados 43 ratos Wistar (200-250g) distribuídos em 4 grupos: sedentário controle (SC), sedentário tratado com DEX (SD), treinado controle (TC) e treinado tratado com DEX (TD). Após um período de adaptação na escada, foi realizado um teste de carregamento máximo (TCM) para determinação da intensidade do treino. Em seguida, os ratos foram submetidos ao treinamento resistido (80% da capacidade máxima, 4 dias/semana, 70 dias) ou mantidos sedentários. Os TCM foram realizados no início do protocolo experimental, após 4 semanas, antes e após o tratamento com DEX. Nos últimos 10 dias, os animais receberam DEX (0,5 mg/kg por dia, i.p.) ou solução salina. Após 24 horas da última sessão de exercício, os animais foram eutanasiados e os músculos flexor longo do hálux (FHL), tibial anterior (TA) e sóleo (SOL) foram coletados, pesados e seus valores normalizados pelo tamanho da tíbia. Analisamos a produção das proteínas mTOR, p70S6K, FOXO3a, Atrogina-1 e MuRF-1. Os resultados são apresentados como média ± EPM, &#945;<0,05. A DEX provocou redução do peso da glândula adrenal (-47%), peso corporal (-21%) e ingestão alimentar (- 28%). O TR aumentou a capacidade física dos animais treinados (+215%). O tratamento com DEX reduziu a massa muscular do FHL e TA (-19,6% e -17,7%, respectivamente), que foi associada ao aumento da proteína MuRF-1 (+37% e +45,5%, respectivamente), não foram observadas alterações nas proteínas mTOR, p70S6K, FOXO3a e Atrogina-1 após o tratamento com DEX. O TR foi capaz de atenuar a atrofia no músculo FHL, pois conseguiu bloquear o aumento da proteína MuRF-1 (-3,5%), além de aumentar os níveis de mTOR (+63% para TC e TD) e p70S6K (+46% e +49% para TC e TD, respectivamente), embora não tenha alterado os valores de FOXO3a e Atrogina-1. O músculo SOL não foi alterado nem pelo tratamento nem pelo treinamento. Portanto, os resultados obtidos até o presente momento permite-nos sugerir que a atrofia observada nos músculos TA e FHL causadas por 10 dias de tratamento com DEX pode estar associada ao aumento da proteína MuRF-1. Por sua vez, o TR foi capaz de prevenir a atrofia no músculo FHL em decorrência do aumento de mTOR e p70S6K somados a manutenção dos valores de MuRF-1.