Models to study intermediate filament dynamics and functions

Intermediate filaments are part of the cytoskeleton and nucleoskeleton; they provide cells with structure and have important roles in cell signalling. The IFs are a large protein family with more than 70 members; each tightly regulated and expressed in a cell type-specific manner. Although the IFs have been known and studied for decades, our knowledge about their specific functions is still limited, despite the fact that mutations in IF genes cause numerous severe human diseases. In this work, three IF proteins are examined more closely; the nuclear lamin A/C and the cytoplasmic nestin and vimentin. In particular the regulation of lamin A/C dynamics, the role of nestin in muscle and body homeostasis as well as the functions and evolutionary aspects of vimentin are investigated. Together this data highlights some less well understood functions of these IFs. We used mass-spectrometry to identify inter-phase specific phosphorylation sites on lamin A. With the use of genetically engineered lamin A protein in combination with high resolution microscopy and biochemical methods we discovered novel roles for this phosphorylation in regulation of lamin dynamics. More specifically, our data suggests that the phosphorylation of certain amino acids in lamin A determines the localization and dynamics of the protein. In addition, we present results demonstrating that lamin A regulates Cdk5-activity. In the second study we use mice lacking nestin to gain more knowledge of this seldom studied protein. Our results show that nestin is essential for muscle regeneration; mice lacking nestin recover more slowly from muscle injury and show signs of spontaneous muscle regeneration, indicating that their muscles are more sensitive to stresses and injury. The absence of nestin also leads to decreased over-all muscle mass and slower body growth. Furthermore, nestin has a role in controlling testicle homeostasis as nestin-/- male mice show a greater variation in testicle size. The common fruit fly Drosophila melanogaster lacks cytoplasmic IFs as most insects do. By creating a fly that expresses human vimentin we establish a new research platform for vimentin studies, as well as provide a new tool for the studies of IF evolution.

Nature of the state economic expanded functions in the Brazilian economy*

ABSTRACT The paper discusses the dynamics of capital accumulation in Latin America economies. The hypothesis is that in these economies the role of the State is comparatively broader than in the economies of the centers of the capitalism by structural reasons. The argument is mainly based on Marx and Kalecki, besides historical elements of Latin America economies, particularly the Brazilian economy. Then the paper explores the dynamics consequences of this nature at the national levels, concluding that this condition gives a higher degree of instability.

Implicit and explicit functions in the acquisition of a phonics rule in the word recognition of learning disabled and non learning disabled students /

One group of 12 non learning disabled students and two groups of 12 learning disabled students between the ges of 10 and 12 were measured on implicit and explicit knowledge cquisition. Students in each group implicitly cquired knowledge bout I of 2 vocabulary rules. The vocabulary rules governed the pronunciation of 2 types of pseudowords. After completing the implicit acquisition phase, all groups were administered a test of implicit knowledge. The non learning disabled group and I learning disabled group were then asked to verbalize the knowledge acquired during the initial phase. This was a test of explicit knowledge. All 3 groups were then given a postlest of implicit knowledge. This tcst was a measure of the effectiveness of the employment of the verbalization technique. Results indicate that implicit knowledge capabilities for both the learning disabled and non learning disabled groups were intact. However. there were significant differences between groups on explicit knowledge capabilities. This led to the conclusion that implicit functions show little individual differences, and that explicit functions are affected by ability difference. Furthermore, the employment of the verbalization technique significantly increased POStlest scores for learning disabled students. This suggested that the use of metacognitive techniques was a beneficial learning tool for learning disabled students.

The roles of ERK1/2 and PI3K in abnormal vascular functions in angiotensin II-infused hypertensive rats

Background: Ang II plays a major role in cardiovascular regulation. Recently, it has become apparent that vascular superoxide anion may play an important role in hypertension development. Treatment with antisense NAD(P)H oxidase or SOD decreased BP in Ang II-infused rats. Wang et al recently reported mice which lack one of the subunits of NAD(P)H oxidase developed hypertension at a much lower extent when compared to the wild type animals infused with Ang II, indicating that superoxide anion contributes to elevation in BP in the Ang II-infused hypertensive model. In the Ang II-infused hypertensive model, altered reactivity of blood vessels is often associated with the elevation of systolic blood pressure. We have observed abnormal tension development and impaired endothelium-dependent relaxation in the isolated aorta of Ang II-infused and DOCA-salt hypertensive rats. Recently, several other cellular signal molecules, including ERK1I2 and PI3K, have been determined to play important roles in the regulation of smooth muscle contraction and relaxation. ERKl/2 and PI3K pathways are also reported to contribute to Ang II induced cell growth, hypertrophy, remodeling and contraction. Moreover, these signaling pathways have shown ROS-sensitive properties. Therefore, the aim of the present study is to investigate the roles of ERKl12 and PI3K in vascular oxidative stress, spontaneous tone and impaired endothelium relaxation in Ang II-infused hypertensive model. Hypothesis: We hypothesize that the activation of ERKl12 and PI3K are elevated in response to an Ang II infusion for 6 days. The elevated activation of phospho-ERKl/2 and PI3K mediated the increased level of vascular superoxide anion, the abnormal vascular contraction and impaired endothelium-dependent vascular relaxation in Ang II-infused hypertensive rats. Methods: Vascular superoxide anion level is measured by lucigenin chemiluminescence. Spontaneous tone and ACh-induced endothelium-dependent relaxation was measured by isometric tension recording in organ chamber. The activity of ERK pathway will be measured by its Western blot of phosphorylation of ERK. PI3K activity was evaluated indirectly by Western blot of the phosphorylation of PDKl, a downstream protein of PI3K signaling pathway. The role of each pathway was also addressed via comparing the responses to the specific inhibitors. Results: Superoxide anion was markedly increased in the isolated thoracic aorta from Ang II-infused rats. There was spontaneous tone developed in rings from Ang II-induced hypertensive but not sham-operated normotensive rats. ACh-induced endothelium-dependent relaxation function is impaired in Ang II-infused hypertensive rats. Superoxide dismutase and NAD(P)H oxidase inhibitor, apocynin, inhibited the abnormal spontaneous tone and ameliorated impaired endothelium-dependent relaxation. The expression of phopho-ERKII2 was enhanced in Ang II-infused rats, indicating the activity of ERK1I2 could be increased. MEK1I2 inhibitors, PD98059 and U126, but not their inactive analogues, SB203580 and U124, significantly reduced the vascular superoxide anion in aortas from Ang II-infused rats. The MEK1I2 inhibitors reduced the spontaneous tone and improved the impaired endothelium-dependent relaxation in aorta of hypertension. These findings supported the role of ERKII2 signaling pathway in vascular oxidative stress, spontaneous tone and impaired endothelium-dependent relaxation in Ang II-infused hypertensive rats. The amount of phospho-PDK, a downstream protein of PI3K was increased in Ang II rats indicating the activity of PI3K activity was elevated. Strikingly, PI3K significantly inhibited the increase of superoxide anion level, abnormal spontaneous tone and restored endothelium-dependent relaxation in Ang II-infused hypertensive rats. These findings indicated the important role of PI3K in Ang II-infused hypertensive rats. Conclusion: ERKII2 and PI3K signaling pathways are sustained activated in Ang II-infused hypertensive rats. The activated ERKII2 and PI3K mediate the increase of vascular superoxide anion level, vascular abnormal spontaneous tone and impaired endothelium-dependent relaxation.

An analysis of decoupling procedures in generating thermal Green's functions of O([lambda]â ´) by the Zubarev equation of motion method

The Zubarev equation of motion method has been applied to an anharmonic crystal of O( ,,4). All possible decoupling schemes have been interpreted in order to determine finite temperature expressions for the one phonon Green's function (and self energy) to 0()\4) for a crystal in which every atom is on a site of inversion symmetry. In order to provide a check of these results, the Helmholtz free energy expressions derived from the self energy expressions, have been shown to agree in the high temperature limit with the results obtained from the diagrammatic method. Expressions for the correlation functions that are related to the mean square displacement have been derived to 0(1\4) in the high temperature limit.