Changes in cell shape and desmin intermediate filament distribution are associated with down-regulation of desmin expression in C2C12 myoblasts grown in the absence of extracellular Ca2+

Desmin is the main intermediate filament (IF) protein of muscle cells. In skeletal muscle, desmin IFs form a scaffold that interconnects the entire contractile apparatus with the subsarcolemmal cytoskeleton and cytoplasmic organelles. The interaction between desmin and the sarcolemma is mediated by a number of membrane proteins, many of which are Ca2+-sensitive. In the present study, we analyzed the effects of the Ca2+ chelator EGTA (1.75 mM) on the expression and distribution of desmin in C2C12 myoblasts grown in culture. We used indirect immunofluorescence microscopy and reverse transcription polymerase chain reaction (RT-PCR) to analyze desmin distribution and expression in C2C12 cells grown in the presence or absence of EGTA. Control C2C12 myoblasts showed a well-spread morphology after a few hours in culture and became bipolar when grown for 24 h in the presence of EGTA. Control C2C12 cells showed a dense network of desmin from the perinuclear region to the cell periphery, whereas EGTA-treated cells showed desmin aggregates in the cytoplasm. RT-PCR analysis revealed a down-regulation of desmin expression in EGTA-treated C2C12 cells compared to untreated cells. The present results suggest that extracellular Ca2+ availability plays a role in the regulation of desmin expression and in the spatial distribution of desmin IFs in myoblasts, and is involved in the generation and maintenance of myoblast cell shape.

A connection between extracellular matrix and hormonal signals during the development of the human fetal adrenal gland

The human adrenal cortex, involved in adaptive responses to stress, body homeostasis and secondary sexual characters, emerges from a tightly regulated development of a zone-specific secretion pattern during fetal life. Its development during fetal life is critical for the well being of pregnancy, the initiation of delivery, and even for an adequate adaptation to extra-uterine life. As early as from the sixth week of pregnancy, the fetal adrenal gland is characterized by a highly proliferative zone at the periphery, a concentric migration accompanied by cell differentiation (cortisol secretion) and apoptosis in the central androgen-secreting fetal zone. After birth, a strong reorganization occurs in the adrenal gland so that it better fulfills the newborn's needs, with aldosterone production in the external zona glomerulosa, cortisol secretion in the zona fasciculata and androgens in the central zona reticularis. In addition to the major hormonal stimuli provided by angiotensin II and adrenocorticotropin, we have tested for some years the hypotheses that such plasticity may be under the control of the extracellular matrix. A growing number of data have been harvested during the last years, in particular about extracellular matrix expression and its putative role in the development of the human adrenal cortex. Laminin, collagen and fibronectin have been shown to play important roles not only in the plasticity of the adrenal cortex, but also in cell responsiveness to hormones, thus clarifying some of the unexplained observations that used to feed controversies.

Comparison of the reliability of multifocal visual evoked cortical potentials generated by pattern reversal and pattern pulse stimulation

This study compared the effectiveness of the multifocal visual evoked cortical potentials (mfVEP) elicited by pattern pulse stimulation with that of pattern reversal in producing reliable responses (signal-to-noise ratio >1.359). Participants were 14 healthy subjects. Visual stimulation was obtained using a 60-sector dartboard display consisting of 6 concentric rings presented in either pulse or reversal mode. Each sector, consisting of 16 checks at 99% Michelson contrast and 80 cd/m² mean luminance, was controlled by a binary m-sequence in the time domain. The signal-to-noise ratio was generally larger in the pattern reversal than in the pattern pulse mode. The number of reliable responses was similar in the central sectors for the two stimulation modes. At the periphery, pattern reversal showed a larger number of reliable responses. Pattern pulse stimuli performed similarly to pattern reversal stimuli to generate reliable waveforms in R1 and R2. The advantage of using both protocols to study mfVEP responses is their complementarity: in some patients, reliable waveforms in specific sectors may be obtained with only one of the two methods. The joint analysis of pattern reversal and pattern pulse stimuli increased the rate of reliability for central sectors by 7.14% in R1, 5.35% in R2, 4.76% in R3, 3.57% in R4, 2.97% in R5, and 1.78% in R6. From R1 to R4 the reliability to generate mfVEPs was above 70% when using both protocols. Thus, for a very high reliability and thorough examination of visual performance, it is recommended to use both stimulation protocols.

A forced running wheel system with a microcontroller that provides high-intensity exercise training in an animal ischemic stroke model

We developed a forced non-electric-shock running wheel (FNESRW) system that provides rats with high-intensity exercise training using automatic exercise training patterns that are controlled by a microcontroller. The proposed system successfully makes a breakthrough in the traditional motorized running wheel to allow rats to perform high-intensity training and to enable comparisons with the treadmill at the same exercise intensity without any electric shock. A polyvinyl chloride runway with a rough rubber surface was coated on the periphery of the wheel so as to permit automatic acceleration training, and which allowed the rats to run consistently at high speeds (30 m/min for 1 h). An animal ischemic stroke model was used to validate the proposed system. FNESRW, treadmill, control, and sham groups were studied. The FNESRW and treadmill groups underwent 3 weeks of endurance running training. After 3 weeks, the experiments of middle cerebral artery occlusion, the modified neurological severity score (mNSS), an inclined plane test, and triphenyltetrazolium chloride were performed to evaluate the effectiveness of the proposed platform. The proposed platform showed that enhancement of motor function, mNSS, and infarct volumes was significantly stronger in the FNESRW group than the control group (P<0.05) and similar to the treadmill group. The experimental data demonstrated that the proposed platform can be applied to test the benefit of exercise-preconditioning-induced neuroprotection using the animal stroke model. Additional advantages of the FNESRW system include stand-alone capability, independence of subjective human adjustment, and ease of use.

O dólar e os desequilíbrios globais

The global expansion of capitalism under American hegemony in the second half of the 20th century has changed the international division of labor and center-periphery scheme proposed under British hegemony. Under the new international division of labor, the United States is forced to generate an ever growing deficit in their trade account in order to accommodate the "mercantilist' expansion of Asian countries, produced by the trans-nationalization of big capital, under American aegis. This form of global economic articulation is at the root of the rupture of the Bretton Woods system and the growing financial liberalization imposed by the hegemonic power over other countries since the 80s.

La reconfiguración economica internacional

The international economic reconfiguration. The developed and developing countries have adjusted with varying degrees of success to the new international order. The world's evolution has not stopped: Europe and the emerging Asian economies, are struggling to create a multipolar World. In the periphery, some countries (Asia) are modernizing at a fast rate, while others (Latin America) are lagging behind and in need to revise their growth strategies. The decentralization of production and trade driven by transnational firms are shifting the geographic distribution of investment and employment. As a result, the industrialized countries have ceased to provide the bulk of the world's savings, changing somehow the foundations of the international financial system.

Uma mestra na periferia do capitalismo: a economia política de Maria da Conceição Tavares

A master in the periphery of capitalism. Maria da Conceição Tavares is an eminent figure in Brazilian economic thought, especially in heterodox circles. She has tackled various issues, such as underdevelopment, from the perspective of a "critique of political economy". The purpose of this article is to identify the main theoretical references, as well as the methodological stance, in Tavares's works, by revisiting the author's critical dialogue with some strands of Political Economy. Although Tavares's work sets up a dialogue with various economists, the paper will focus on her interpretation of Marx, Keynes and Kalecki, whose ideas are of utmost importance for the construction of her analytical framework.

Reciprocidade implícita e crescimento na economia internacional: uma perspectiva estruturalista

Implicit reciprocity and growth in the international economy: a structuralist perspective. This paper discusses some of the structuralist ideas about international coordination and growth in an international system formed by countries whose productive structures and technological capabilities are strongly asymmetric. These ideas are formalized taking as a point of departure the Keynesian Balance-of-Payments constrained growth model with two countries. To this model is added a function (based on the catching up literature) in which the income elasticity of the demand for exports and imports depends on the technology gap. The model allows for discussing the inter-relations between the fiscal and the industrial and technological policies. It also allows for finding the rate of growth of autonomous expenditure in the periphery which ensures that it will use all the foreign exchange it earns in promoting economic growth (the principle of "automatic reciprocity").

Historical origins of Brazilian relative backwardness

This paper relies on some data to identify the 19th century as the major period in which Brazil economy lagged behind some chosen benchmarking countries, as the USA, Canada, New Zealand, Australia and some European periphery countries. To identify the reasons for this an exercise using immigration data was used to make a decomposition of the sources of growth of the proportion of the USA per capita GDP to the Brazilian one. The results indicate that the imported human capital was responsible for 59% to 88% of this total growth between 1820 and 1900.

Chronic macro-economic and financial imbalances in the world economy: a meta-economic view

Global finance, combining offshore banking and universal banks to drive a broader globalization process, has transformed the modus operandi of the world economy. This requires a new "meta-economic" framework in which short-term portfolio-investment flows are treated as the dominant phenomenon they have become. Organized by global finance, these layered bi-directional flows between center and periphery manage a tension between financial concentration and monetary fragmentation. The resulting imbalances express the asymmetries built into that tension and render the exchange rate a more strategic policy variable than ever.

The structuralist tradition in economics: methodological and macroeconomics aspects

This paper examines the structuralist tradition in economics, emphasizing the role that structures play in the economic growth of developing countries. Since the subject at hand is evidently too large to cover in a single article, an emphasis has been brought to bear upon the macroeconomic elements of such a tradition, while also exploring its methodological aspects. It begins by analysing some general aspects of structuralism in economics (its evolution and origins) associated with ECLAC thought, in this instance focusing on the dynamics of the center-periphery relationship. Thereafter, the macroeconomic structuralism derived from the works of Taylor (1983, 1991) is presented, followed by a presentation of neo-structuralism. Centred on the concept of systemic competitiveness, this approach defines a strategy to achieve the high road of globalization, understood here as an inevitable process in spite of its engagement being dependent on the policies adopted. The conclusions show the genuine contributions of this tradition to economic theory.

The concept of emerging power in international politics and economy

ABSTRACT This paper aims to analyze the concept of emerging power established to the understanding of international affairs. The work observes that the use of the lexicon emerging - regarding to markets, countries or powers - as qualifier for a range of international relations phenomena became a constituent part of the matter. In spite of that, the empirical denotation of the predicate is ahead of the amount of efforts on its theoretical contextualization. Our methodological hypothesis is that the rational denial of the concepts prevailing connotative spectrum by acknowledging the embedded wisdom about cognate phenomena synthesizes a theoretical framework on its accurate use.