Hypoxia stimulates via separate pathways ERK phosphorylation and NF-kappaB activation in skeletal muscle cells in primary culture.

Mammalian cells sense oxygen levels and respond to hypoxic conditions through the regulation of multiple signaling pathways and transcription factors. Here, we investigated the effects of hypoxia on the activity of two transcriptional regulators, ERK1/2 and NF-kappaB, in skeletal muscle cells in primary culture. We found that hypoxia significantly enhanced ERK1/2 phosphorylation and that it stimulated NF-kappaB-dependent gene transcription as well as nuclear translocation of a green fluorescent protein-labeled p65 NF-kappaB isoform. Phosphorylation of ERK1/2- and NF-kappaB-dependent transcription by hypoxia required calcium entry through L-type calcium channels. Calcium release from ryanodine-sensitive stores was also necessary for ERK1/2 activation but not for NF-kappaB-dependent-transcription. N-acetylcysteine, a general scavenger of reactive oxygen species, blocked hypoxia-induced ROS generation but did not affect the stimulation of ERK1/2 phosphorylation induced by hypoxia. In contrast, NF-kappaB activation was significantly inhibited by N-acetylcysteine and did not depend on ERK1/2 stimulation, as shown by the lack of effect of the upstream ERK inhibitor U-0126. These separate pathways of activation of ERK1/2 and NF-kappaB by hypoxia may contribute to muscle adaptation in response to hypoxic conditions.

A review on electron microscopy and neurotransmitter systems.

The purpose of this article is to review the contributions of transmission electron microscopy studies to the understanding of brain circuits and neurotransmitter systems. Our views on the microstructure of connections between neurons have gradually changed, and now we recognize that the classical mental image we had on a chemical synapse is no longer applicable to every neuronal connection. We highlight studies that converge to point out that, while the most prevalent fast transmitters in the brain, glutamate and GABA, are stored in small, clear synaptic vesicles (SSV) and released at synapses, neuropeptides are exclusively stored in large dense core vesicles (LDCV) and released extrasynaptically. Amine transmitters are preferentially, but not exclusively, accumulated in LDCV and may be released at synaptic or extrasynaptic sites. We discuss evidence suggesting that axon terminals from pyramidal cortical neurons and dorsal thalamic neurons lack LDCV and therefore could not use neuropeptides as transmitters. This idea fits with the fast, high temporal resolution information processing that characterizes cortical and thalamic function.

Depolarization of skeletal muscle cells induces phosphorylation of cAMP response element binding protein via calcium and protein kinase Calpha.

Membrane depolarization of skeletal muscle cells induces slow inositol trisphosphate-mediated calcium signals that regulate the activity of transcription factors such as the cAMP-response element-binding protein (CREB), jun, and fos. Here we investigated whether such signals regulate CREB phosphorylation via protein kinase C (PKC)-dependent pathways. Western blot analysis revealed the presence of seven isoforms (PKCalpha, -betaI, -betaII, -delta, -epsilon, -, and -zeta) in rat primary myotubes. The PKC inhibitors bisindolymaleimide I and Gö6976, blocked CREB phosphorylation. Chronic exposure to phorbol ester triggered complete down-regulation of several isoforms, but reduced PKCalpha levels to only 40%, and did not prevent CREB phosphorylation upon myotube depolarization. Immunocytochemical analysis revealed selective and rapid PKCalpha translocation to the nucleus following depolarization, which was blocked by 2-amino-ethoxydiphenyl borate, an inositol trisphosphate receptor inhibitor, and by the phospholipase C inhibitor U73122. In C2C12 cells, which expressed PKCalpha,-epsilon, and -zeta, CREB phosphorylation also depended on PKCalpha. These results strongly implicate nuclear PKCalpha translocation in CREB phosphorylation induced by skeletal muscle membrane depolarization.

Signal transduction and gene expression regulated by calcium release from internal stores in excitable cells.

Calcium regulation of several transcription factors involves different calcium-dependent signaling cascades and engages cytoplasmic as well as nuclear calcium signals. The study of the specific sources of calcium signals involved in regulation of gene expression in skeletal muscle has been addressed only recently. In this tissue, most cytoplasmic and nuclear calcium signals originate from calcium release from internal stores, mediated either by ryanodine receptor (RyR) or IP3 receptor (IP3R) channels. The latter are located both in the sarcoplasmic reticulum (SR) and in the nuclear membrane, and their activation results in long-lasting nuclear calcium increase. The calcium signals mediated by RyR and IP3R are very different in kinetics, amplitude and subcellular localization; an open question is whether these differences are differentially sensed by transcription factors. In neurons, it is well established that calcium entry through L-type calcium channels and NMDA receptors plays a role in the regulation of gene expression. Increasing evidence, however, points to a role for calcium release from intracellular stores in this process. In this article, we discuss how RyR-mediated calcium release contributes to the activation of the calcium-dependent transcription factor CREB and the subsequent LTP generation. We present novel results from our laboratory showing ERK-mediated CREB activation by hydrogen peroxide. This activation takes place in the absence of extracellular calcium and is blocked by inhibitory ryanodine concentrations, suggesting it is caused by redox activation of RyR-mediated calcium release.

Signal transduction and gene expression regulated by calcium release from internal stores in excitable cells

Calcium regulation of several transcription factors involves different calcium-dependent signaling cascades and engages cytoplasmic as well as nuclear calcium signals. The study of the specific sources of calcium signals involved in regulation of gene expression in skeletal muscle has been addressed only recently. In this tissue, most cytoplasmic and nuclear calcium signals originate from calcium release from internal stores, mediated either by ryanodine receptor (RyR) or IP3 receptor (IP3R) channels. The latter are located both in the sarcoplasmic reticulum (SR) and in the nuclear membrane, and their activation results in long-lasting nuclear calcium increase. The calcium signals mediated by RyR and IP3R are very different in kinetics, amplitude and subcellular localization; an open question is whether these differences are differentially sensed by transcription factors. In neurons, it is well established that calcium entry through L-type calcium channels and NMDA receptors plays a role in the regulation of gene expression. Increasing evidence, however, points to a role for calcium release from intracellular stores in this process. In this article, we discuss how RyR-mediated calcium release contributes to the activation of the calcium-dependent transcription factor CREB and the subsequent LTP generation. We present novel results from our laboratory showing ERK-mediated CREB activation by hydrogen peroxide. This activation takes place in the absence of extracellular calcium and is blocked by inhibitory ryanodine concentrations, suggesting it is caused by redox activation of RyR-mediated calcium release.

Depolarization-induced slow calcium transients activate early genes in skeletal muscle cells.

The signaling mechanisms by which skeletal muscle electrical activity leads to changes in gene expression remain largely undefined. We have reported that myotube depolarization induces calcium signals in the cytosol and nucleus via inositol 1,4,5-trisphosphate (IP(3)) and phosphorylation of both ERK1/2 and cAMP-response element-binding protein (CREB). We now describe the calcium dependence of P-CREB and P-ERK induction and of the increases in mRNA of the early genes c-fos, c-jun, and egr-1. Increased phosphorylation and early gene activation were maintained in the absence of extracellular calcium, while the increase in intracellular calcium induced by caffeine could mimic the depolarization stimulus. Depolarization performed either in the presence of the IP(3) inhibitors 2-aminoethoxydiphenyl borate or xestospongin C or on cells loaded with BAPTA-AM, in which slow calcium signals were abolished, resulted in decreased activation of the early genes examined. Both early gene activation and CREB phosphorylation were inhibited by ERK phosphorylation blockade. These data suggest a role for calcium in the transcription-related events that follow membrane depolarization in muscle cells.

IP3 dependent Ca2+ signals in muscle cells are involved in regulation of gene expression.

Potassium depolarization of cultured muscle cells was employed to study cellular responses linked to calcium signaling. Events occurring after depolarization include i) A transient increase of the IP3 mass (2-10s); ii) A slow calcium transient (5 to 25s) that propagates as a low concentration wave along the myotube showing a distinct calcium transient at the level of cell nuclei. Due to the presence of IP3 receptors both in the SR (A-band region) and in the nuclear envelope, these two events appear to be related; iii) Phosphorylation of mitogen activated kinases (ERK 1/2) and of the transcription factor CREB (30 s-10 min), as well as expression of the early genes c-fos, c-jun and egr-1 mRNA (5-15 min). Several independent pieces of evidence, including results obtained using inhibitors specific for individual steps, allowed us to connect these in a sequential manner. As the same type of signaling cascade can be triggered by oxidants, neurotransmitters and hormones, the ensemble of results allows us to propose a general model to describe signaling events that link membrane stimulation to regulation of gene transcription in skeletal muscle cells.

IP3 dependent Ca2+ signals in muscle cells are involved in regulation of gene expression

Potassium depolarization of cultured muscle cells was employed to study cellular responses linked to calcium signaling. Events occurring after depolarization include i) A transient increase of the IP3 mass (2-10s); ii) A slow calcium transient (5 to 25s) that propagates as a low concentration wave along the myotube showing a distinct calcium transient at the level of cell nuclei. Due to the presence of IP3 receptors both in the SR (A-band region) and in the nuclear envelope, these two events appear to be related; iii) Phosphorylation of mitogen activated kinases (ERK 1/2) and of the transcription factor CREB (30 s-10 min), as well as expression of the early genes c-fos, c-jun and egr-1 mRNA (5-15 min). Several independent pieces of evidence, including results obtained using inhibitors specific for individual steps, allowed us to connect these in a sequential manner. As the same type of signaling cascade can be triggered by oxidants, neurotransmitters and hormones, the ensemble of results allows us to propose a general model to describe signaling events that link membrane stimulation to regulation of gene transcription in skeletal muscle cells

O saber de enfermagem na assistência à hanseníase no Estado de São Paulo / The nursing knowledge in the leprosy care in São Paulo state

Neste trabalho, a preocupação metodológica abrange os estudos dos Modelos Tecno-Assistenciais em Saúde que embasaram as concepções dos formuladores de Políticas Públicas, normatizando saberes e práticas relativas ao cuidado do doente de Hanseníase. O estudo das correntes ligadas a esses modelos, visaram mostrar, a partir de seu campo de saberes e práticas, como o enfermeiro utiliza-se das fundamentações teóricas instituídas pela saúde pública e medicina para conformar a assistência em Hanseníase, a partir da década de 50. O trabalho apresenta também as fontes teóricas elaboradas pela própria enfermagem desde suas origens com Florence Nightingale e mais recentemente com as proposições das enfermeiras cientificistas norte-americanas. Os dados qualitativos da pesquisa revelam que a enfermagem, ao enveredar pela Saúde Pública, toma para si as proposições desse campo de saber, tal como foram concebidas pela ótica médica e acaba por se distanciar de suas propostas originais, quanto a uma assistência sistemática e cuidadosa ao paciente. A adesão duradora aos pressupostos da Saúde Pública criou dificuldades para gerar transformações de impacto no modo de acolher e cuidar dos portadores de Hanseíanse, na direção em que os enfermeiros apontaram quando assumiram a assistência de enfermagem a esses doentes. Esta situação propiciou um empobrecimento quanto à aquisição de novos conhecimentos à medida em que houve uma acomodação frente a saeres e práticas já constituídos sob a perspectiva da doença. A construção de novos modelos tecno-assistenciais em enfermagem exige que o enfermeiro retome os postulados próprios, buscando saberes e práticas baseadas no seu campo de conhecimento e que toma o cuidado do doente como seu eixo estruturante. Nesse sentido, faz-se necessário propostas que se voltem para um atendimento mais humano e integralizado, visando a participação do doente e sua família no tratamento proposto.

O doente de hanseníase em Campinas: uma perspectiva antropológica / People with leprosy in Campinas, Brazil: an anthropological perspective

Estuda a experiência de vida de doentes e comunicantes de hanseníase em Campinas, Brasil, a partir da análise de suas representaçoes sobre saúde, doença e terapêutica. Trata-se de captar no interior das condiçoes de vida e de trabalho destes indivíduos as estratégias que permitam adaptaçäo ao meio social e familiar, subsistência e convivência com a doença. Atençäo especial é dada à maneira pela qual estes indivíduos enfrentam o problema de manutençäo e recuperaçäo da saúde, assim como avaliam os serviçoes e as práticas oficiais e näo-oficiais de saúde.

Situaçäo epidemiológica da hanseníase e dos seus comunicantes em Campinas / The epidemiological status of Leprosy patients and their communiccants in Campinas

A Hanseníase é uma doença endêmica e de alta prevalência entre a populaçäo do país. Das endemias brasileiras, essa é a de mais longa duraçäo, trazendo como consequência, um problema social de importância extremamente relevante. O presente estudo analisa a situaçäo epidemiológica da hanseníase no município de Campinas. O quadro epidemiológico aponta para o controle dos comunicantes de hanseníase neste município que continua pouco eficiente, demonstrando necessidade de estudos mais aprofundados que privilegie estes atores sociais täo importantes na cadeia do processo epidemiológico da hanseníase.

Influência das escolas de administraçäo científica e clássica na produçäo científica da enfermagem brasileira / Influence of the scientific and classical schools of administration in the scientific output of brazilian nursing

Este trabalho estuda a influência de F.W. Taylor e H. Fayol na produçäo científica da enfermagem brasileira, desde 1930 até 1980. É estudada a produçäo científica da enfermagem brasileira, procurando trabalhos baseados nas Escolas de Administraçäo Científica e Clássica. A autora faz um levantamento bibliográfico baseado em duas publicaçöes: a Revista Brasileira de Enfermagem e Revista Paulista de Hospitais. Foram selecionados e estudados 68 trabalhos. Os achados mostram que Taylor/Fayol tiveram e ainda tem uma influência importante na fundamentaçäo teórica da produçäo científica da enfermagem. A temática principal dos trabalhos se refere a estudos sobre "A Organizaçäo do Serviço de Enfermagem Hospitalar e, "Estudos de Tempo e Movimento de Atividades de Técnicas de Enfermagem". A preocupaçäo central destes textos é com a produtividade e a racionalidade do trabalho. Isto näo leva em conta que a organizaçäo do trabalho na saúde e na enfermagem é um trabalho humano no atendimento das necessidades de saúde.

Influência das escolas de administraçäo científica e clássica na produçäo científica da enfermagem brasileira / Influence of the scientific and classical schools of administration in the scientific output of brazilian nursing

Esta dissertaçäo de mestrado objetivou estudar a importância de F. W. Taylor e H. Fayol na Produçäo Científica da Enfermagem Brasileira, a partir da década de 30 até a atualidade. Para identificar esta influência fizemos um estudo da produçäo científica da enfermagem brasileira buscando aquelas produçöes que fundamentavam-se nas Escolas de Administraçäo Científica e Clássica. Trouxemos a fundamentaçäo teórica destes dois teóricos porque foram eles que estudaram a organizaçäo do trabalho e a estrutura empresarial e como tal queremos problematizar o porque do predomínio da organizaçäo do trabalho das empresas capitalistas nos serviços de saúde e em especial na enfermagem. A técnica da pesquisa utilizada por nós foi o levantamento bibliográfico, em dois periódicos: na Revista Brasileira de Enfermagem e Revista Paulista de Hospitais, perfazendo um total de 129 textos levantados em administraçäo geral. Destes, selecionamos 68 que fundamentaram-se em Taylor e Fayol. Nossos achados nos mostraram que estes dois teóricos tiveram um forte papel na produçäo científica da enfermagem de maneira explícita e implícita e consequentemente na prática de enfermagem. A temática dos textos centrou-se em dois direcionamentos: Estudos da Organizaçäo do Serviço de Enfermagem Hospitalar e Estudos de Tempo e Movimento. A preocupaçäo central desses textos é com a produtividade e a racionalidade do trabalho. Somente na década de 80 é que surgiram trabalhos fazendo uma análise crítica aos fundamentos teóricos destas duas escolas clássicas, combatendo a crescente especializaçäo e divisäo de trabalho na saúde. O objeto de trabalho da enfermeira tem uma especificidade que é o exercício da funçäo administrativa centralizada na assistência do paciente e portanto necessita de um referencial teórico que contemple este objeto direcionando-se para a integralidade da assistência.