Beta(1)-selective agonist (-)-1-(3,4-dimethoxyphenetylamino)-3-(3,4-dihydroxy)-2-propanol [(-)-RO363] differentially interacts with key amino acids responsible for beta(1)-selective binding in resting and active states.

(-)-1-(3,4-Dimethoxyphenetylamino)-3-(3,4-dihydroxy)-2-propanol [(-)-RO363] is a highly selective beta(1)-adrenergic receptor (beta(1)AR) agonist. To study the binding site of beta(1)-selective agonist, chimeric beta(1)/beta(2)ARs and Ala-substituted beta(1)ARs were constructed. Several key residues of beta(1)AR [Leu(110) and Thr(117) in transmembrane domain (TMD) 2], and Phe(359) in TMD 7] were found to be responsible for beta(1)-selective binding of (-)-RO363, as determined by competitive binding. Based on these results, we built a three-dimensional model of the binding domain for (-)-RO363. The model indicated that TMD 2 and TMD 7 of beta(1)AR form a binding pocket; the methoxyphenyl group of N-substituent of (-)-RO363 seems to locate within the cavity surrounded by Leu(110), Thr(117), and Phe(359). The amino acids Leu(110) and Phe(359) interact with the phenyl ring of (-)-RO363, whereas Thr(117) forms hydrogen bond with the methoxy group of (-)-RO363. To examine the interaction of these residues with beta(1)AR in an active state, each of the amino acids was changed to Ala in a constitutively active (CA)-beta(1)AR mutant. The degree of decrease in the affinity of CA-beta(1)AR for (-)-RO363 was essentially the same as that of wild-type beta(1)AR when mutated at Leu(110) and Thr(117). However, the affinity was decreased in Ala-substituted mutant of Phe(359) compared with that of wild-type beta(1)AR. These results indicated that Leu(110) and Thr(117) are necessary for the initial binding of (-)-RO363 with beta(1)-selectivity, and interaction of Phe(359) with the N-substituent of (-)-RO363 in an active state is stronger than in the resting state.

Different internalization properties of the alpha1a- and alpha1b-adrenergic receptor subtypes: the potential role of receptor interaction with beta-arrestins and AP50.

The internalization properties of the alpha1a- and alpha1b-adrenergic receptors (ARs) subtypes transiently expressed in human embryonic kidney (HEK) 293 cells were compared using biotinylation experiments and confocal microscopy. Whereas the alpha1b-AR displayed robust agonist-induced endocytosis, the alpha1a-AR did not. Constitutive internalization of the alpha1a-AR was negligible, whereas the alpha1b-AR displayed significant constitutive internalization and recycling. We investigated the interaction of the alpha1-AR subtypes with beta-arrestins 1 and 2 as well as with the AP50 subunit of the clathrin adaptor complex AP2. The results from both coimmunoprecipitation experiments and beta-arrestin translocation assays indicated that the agonistinduced interaction of the alpha1a-AR with beta-arrestins was much weaker than that of the alpha1b-AR. In addition, the alpha1a-AR did not bind AP50. The alpha1b-AR mutant M8, lacking the main phosphorylation sites in the receptor C tail, was unable to undergo endocytosis and was profoundly impaired in binding beta-arrestins despite its binding to AP50. In contrast, the alpha1b-AR mutant DeltaR8, lacking AP50 binding, bound beta-arrestins efficiently, and displayed delayed endocytosis. RNA interference showed that beta-arrestin 2 plays a prominent role in alpha1b-AR endocytosis. The findings of this study demonstrate differences in internalization between the alpha1a- and alpha1b-AR and provide evidence that the lack of significant endocytosis of the alpha1a-AR is linked to its poor interaction with beta-arrestins as well as with AP50. We also provide evidence that the integrity of the phosphorylation sites in the C tail of the alpha1b-AR is important for receptor/beta-arrestin interaction and that this interaction is the main event triggering receptor internalization.

Molecular mechanisms involved in the activation and regulation of the alpha 1-adrenergic receptor subtypes.

The adrenergic receptors (ARs) belong to the superfamily of membrane-bound G protein coupled receptors (GPCRs). Our investigation has focused on the structure-function relationship of the alpha 1b-AR subtype used as the model system for other GPCRs. Site-directed mutagenesis studies have elucidated the structural domains of the alpha 1b-AR involved in ligand binding, G protein coupling or desensitization. In addition, a combined approach using site-directed mutagenesis and molecular dynamics analysis of the alpha 1b-AR has provided information about the potential mechanisms underlying the activation process of the receptor, i.e. its transition from the 'inactive' to the 'active' conformation.

The A-kinase anchoring protein (AKAP)-Lbc-signaling complex mediates alpha1 adrenergic receptor-induced cardiomyocyte hypertrophy.

In response to various pathological stresses, the heart undergoes a pathological remodeling process that is associated with cardiomyocyte hypertrophy. Because cardiac hypertrophy can progress to heart failure, a major cause of lethality worldwide, the intracellular signaling pathways that control cardiomyocyte growth have been the subject of intensive investigation. It has been known for more than a decade that the small molecular weight GTPase RhoA is involved in the signaling pathways leading to cardiomyocyte hypertrophy. Although some of the hypertrophic pathways activated by RhoA have now been identified, the identity of the exchange factors that modulate its activity in cardiomyocytes is currently unknown. In this study, we show that AKAP-Lbc, an A-kinase anchoring protein (AKAP) with an intrinsic Rho-specific guanine nucleotide exchange factor activity, is critical for activating RhoA and transducing hypertrophic signals downstream of alpha1-adrenergic receptors (ARs). In particular, our results indicate that suppression of AKAP-Lbc expression by infecting rat neonatal ventricular cardiomyocytes with lentiviruses encoding AKAP-Lbc-specific short hairpin RNAs strongly reduces both alpha1-AR-mediated RhoA activation and hypertrophic responses. Interestingly, alpha1-ARs promote AKAP-Lbc activation via a pathway that requires the alpha subunit of the heterotrimeric G protein G12. These findings identify AKAP-Lbc as the first Rho-guanine nucleotide exchange factor (GEF) involved in the signaling pathways leading to cardiomyocytes hypertrophy.

[Recueil composite].

Contient : Job, cum commentariis ; Fridegisus, Tractatus de grammatica (34-36). - S. Bonifatius, Ars grammatica (36v-47v, 58-70). - Tatuinus, Ars grammatica (48, 57, 49-56v, 79-86, 71-78v)

The alpha(1A/C)- and alpha(1B)-adrenergic receptors are required for physiological cardiac hypertrophy in the double-knockout mouse.

Catecholamines and alpha(1)-adrenergic receptors (alpha(1)-ARs) cause cardiac hypertrophy in cultured myocytes and transgenic mice, but heart size is normal in single KOs of the main alpha(1)-AR subtypes, alpha(1A/C) and alpha(1B). Here we tested whether alpha(1)-ARs are required for developmental cardiac hypertrophy by generating alpha(1A/C) and alpha(1B) double KO (ABKO) mice, which had no cardiac alpha(1)-AR binding. In male ABKO mice, heart growth after weaning was 40% less than in WT, and the smaller heart was due to smaller myocytes. Body and other organ weights were unchanged, indicating a specific effect on the heart. Blood pressure in ABKO mice was the same as in WT, showing that the smaller heart was not due to decreased load. Contractile function was normal by echocardiography in awake mice, but the smaller heart and a slower heart rate reduced cardiac output. alpha(1)-AR stimulation did not activate extracellular signal-regulated kinase (Erk) and downstream kinases in ABKO myocytes, and basal Erk activity was lower in the intact ABKO heart. In female ABKO mice, heart size was normal, even after ovariectomy. Male ABKO mice had reduced exercise capacity and increased mortality with pressure overload. Thus, alpha(1)-ARs in male mice are required for the physiological hypertrophy of normal postnatal cardiac development and for an adaptive response to cardiac stress.

O Habitar Mínimo

O espaço mínimo é um tema sobre qual se tem debruçado o trabalho de muitos arquitectos, e que continua a alimentar reflexões e obras construídas de grande interesse. Uma vez que a habitação é o programa por excelência nesse tipo de investigação, estudam-se as pesquisas realizadas desde o século passado sobre o tema da casa mínima, em que se verifica uma evolução no enfoque do problema, de que se passa do doméstico para o urbano, da casa à cidade. Estudam-se também intervenções sobre o existente quando este se mostra desadequado aos standards contemporâneos de habitabilidade. Duma primeira análise, percebe-se que essa produção pode ter dois processos de concepção distintos, uma que está ligada a uma visão poética do mínimo e consequente depreciação do supérfluo, e outra, mais pragmática, fortemente ligada à prática de arquitectura em contextos de escassez de recursos. Nestes contextos o espaço é mínimo como resultado da falta de recursos, pelo que existe uma procura constante para superar essa limitação, de modo que se estudam casos exemplares que o fazem com sucesso. Tendo em conta que essa procura mantêm, naturalmente, uma forte relação com o fazer, com a dimensão tectónica do espaço mínimo, dedica-se um capítulo da presente dissertação a intervenções que desenvolvem uma investigação em torno da construção em contextos de escassez, de sistemas construtivos e materiais que ao serem utilizados trazem uma mais valia ao espaço construído, qualitativamente e quantitativamente.

A análise de redes sociais no mundo lusófono: contributos para o conhecimento de uma comunidade científica em desenvolvimento

Neste artigo visamos caraterizar um conjunto de investigadores da área das ciências sociais que se distinguem pela utilização da análise de redes sociais (ars) como perspetiva teórico-metodológica e que circunscrevemos à partilha da língua portuguesa. A partir da caraterização sociográfica e da medição do sistema de interdependências entre estes investigadores (colaboração, aconselhamento e coautoria) pretendemos contribuir para a compreensão do desenvolvimento da ars no mundo lusófono, esboçando hipóteses explicativas dos fatores inibidores e estimulantes do seu desenvolvimento neste contexto linguístico.

Fortifications. Etat, en forme de mémoire, des souterrains et des battimens militaires qui sont à la citadelle de Saint-Jean-Pied-de-Port

Ancien possesseur : Argenson, Antoine-René de Voyer (1722-1787 ; marquis de Paulmy d')

L'aventura difícil d'ésser humans: l'exili en la lírica de Mercè Rodoreda

Treball de recerca realitzat per alumnes d’ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l’any 2010. L’objectiu principal de la recerca és determinar si l'exili franquista afectà l'obra poètica de Mercè Rodoreda i, conseqüentment, en quin grau està present en les seves composicions. Així, doncs, es pretén analitzar la influència del transterrament a partir dels temes, paisatges, metàfores, imatges i símbols existents en els seus sonets. La metodologia emprada per elaborar la recerca es basa, inicialment, en un buidatge bibliogràfic d'articles i d'altres documents que tracten el tema de l'exili en la lírica catalana. Seguidament, es confecciona una llista amb possibles poetes a tractar i s'escull Mercè Rodoreda, amb la consegüent lectura i elecció d'obres poètiques a analitzar. Paral•lelament, s'elaboren fitxes on es fa constar la temàtica i els símbols recurrents de les composicions. Finalment, es posa en comú la informació extreta, tot elaborant una anàlisi simbolicoliterària i mitocrítica per extreure’n conclusions. Es pot afirmar que la lírica de Mercè Rodoreda està completament supeditada a les seves vivències d'exili. Tot i que la poeta no explicita el dolor provocat per la diàspora en cap composició, la seva antologia és plena de vocables amb connotació fosca i imatges ombrívoles. La poesia rodorediana es basa en l'evocació de sentiments tristos, melangiosos, dolorosos, d'angoixa vital i de mort, es basa en la lírica de l'eterno dolore, on hi impera una profunda imprecació elegíaca.

Mémoire d'observation sur la carte de la valée de Bareige, l'un des passages de France et d'Espagne

Ancien possesseur : Argenson, Antoine-René de Voyer (1722-1787 ; marquis de Paulmy d')

Mémoire sur le quay projetté le long de la gorge de l'ouvrage à corne qui couvre l'espace entre les bastions (31) et (26) de la ville de Perpignan pour y faire passer le grand chemin d'Espagne

Ancien possesseur : Argenson, Antoine-René de Voyer (1722-1787 ; marquis de Paulmy d')

Entre Nós : entrevista a José Luís Tavares

Entrevista ao poeta cabo-verdiano José Luís Tavares, distinguido com o Prémio Mário António de Poesia 2004, atribuído pela Fundação Calouste Gulbenkian, pela sua primeira obra poética “Paraíso apagado por um trovão”.

Borges: fervor de Dante

Ya son más de una docena los estudios dedicados a la asimilación de Dante en la obra de Borges, pero la dispersión bibliográfica y la carencia de una edición crítica de los textos borgesianos pueden suponer un obstáculo serio para quien pretenda estudiar este aspecto de forma sistemática. Por ello, en este artículo se ofrece una síntesis de los problemas que entraña la presencia de Dante en Borges (cronología de su presencia, tendencias de la crítica y significado de Dante en la poética del escritor argentino). También se ofrece un corpus, ordenado y completo, de las menciones de Dante en las narraciones, ensayos y poemas del bonaerense, que incluye los ensayos que este dedicó a la Comedia, los recuerdos autobiográficos que le conciernen, las menciones generales y precisas, y los comentaristas de Dante que citó a lo largo de sus textos