Search results for "Fibril"
showing 10 items of 836 documents
Astrocytes give rise to new neurons in the adult mammalian hippocampus
2001
Neurogenesis in the dentate gyrus of the hippocampus persists throughout life in many vertebrates, including humans. The progenitors of these new neurons reside in the subgranular layer (SGL) of the dentate gyrus. Although stem cells that can self-renew and generate new neurons and glia have been cultured from the adult mammalian hippocampus, the in vivo primary precursors for the formation of new neurons have not been identified. Here we show that SGL cells, which express glial fibrillary acidic protein and have the characteristics of astrocytes, divide and generate new neurons under normal conditions or after the chemical removal of actively dividing cells. We also describe a population o…
Analysis of NO synthase expression in neuronal, astroglial and fibroblast-like derivatives differen-tiating from PCC7-Mzl embryonic carcinoma cells
1999
We studied the expression of the NO synthase isoforms in an in vitro model of neural development using RT-PCR, Western blot and immu- nohistochemistry. Murine PCC7-Mzl cells (Jostock et al., Eur. J. Cell Biol. 76, 63–76,1998) differentiate in the presence of all-trans retinoic acid and dibutyryl cAMP along the neural pathway into neuron-like, fibroblast-like and astroglia-like cells. Undifferentiated cells showed immunofluorescent staining for neuronal-type NOSI and endothelial- type NOS III. This expression pattern was retained in those cells differ entiating into neurofilament- and tau protein-positive neuronal cells. Thymocyte alloantigen (Thyl.2/CD 90.2)-positive Fibroblasts, appearing …
A novel multielectrode for epicardial recording with temperature control based in Peltier cells
2009
Electrophysiological parameters of the myocardium are influenced by temperature. Working with experimental models of isolated heart, the analysis of modulating effect exerted by local changes of temperature can provide some information about the mechanisms of certain arrhythmias and their electrophysiological bases, such as ventricular fibrillation. Conventional multiple electrodes do not seem to be appropriate, being necessary the development of specific devices. The design and implementation of a device adapted to these requirements is presented in this paper. This is a multi-electrode able to reproduce located and controlled conditions of hypothermia and hyperthermia, in a determined are…
Analyzing the electrophysiological effects of local epicardial temperature in experimental studies with isolated hearts
2008
As a result of their modulating effects upon myocardial electrophysiology, both hypo- and hyperthermia can be used to study the mechanisms that generate or sustain cardiac arrhythmias. The present study describes an original electrode developed with thick-film technology and capable of controlling regional temperature variations in the epicardium while simultaneously registering its electrical activity. In this way, it is possible to measure electrophysiological parameters of the heart at different temperatures. The results obtained with this device in a study with isolated and perfused rabbit hearts are reported. An exploration has been made of the effects of local temperature changes upon…
Morphology of experimentally denervated and reinnervated rat facial muscle I. Histochemical and histological findings
1994
The morphological changes in rat facial muscles were evaluated after permanent denervation and were compared with findings after immediate reinnervation. Thirty rats underwent transection of the left and right facial nerves immediately followed by hypoglossal-facial nerve anastomosis on the right side (muscular reinnervation) and removal of 8-10 mm of the facial plexus on the left side (permanent muscular denervation). Levator labii muscle samples of both sides were collected sequentially at 2, 6, 7, 10, 20, and 24 weeks after surgery and submitted to routine histological and enzyme histochemical staining procedures. In normal levator labii muscles a typical "chessboard" pattern was found, …
Nouvelles perspectives concernant la structure et la fonction du domaine carboxyl terminal de Hfq
2015
Accumulating evidence indicates that RNA metabolism components assemble into supramolecular cellular structures to mediate functional compartmentalization within the cytoplasmic membrane of the bacterial cell. This cellular compartmentalization could play important roles in the processes of RNA degradation and maturation. These components include Hfq, the RNA chaperone protein, which is involved in the post-transcriptional control of protein synthesis mainly by the virtue of its interactions with several small regulatory ncRNAs (sRNA). The Escherichia coli Hfq is structurally organized into two domains. An N-terminal domain that folds as strongly bent β-sheets within individual protomers to…
Self-Organization Pathways and Spatial Heterogeneity in Insulin Amyloid Fibril Formation
2009
At high temperature and low pH, the protein hormone insulin is highly prone to form amyloid fibrils, and for this reason it is widely used as a model system to study fibril formation mechanisms. In this work, we focused on insulin aggregation mechanisms occurring in HCl solutions (pH 1.6) at 60 degrees C. By means of in situ Thioflavin T (ThT) staining, the kinetics profiles were characterized as a function of the protein concentration, and two concurrent aggregation pathways were pointed out, being concentration dependent. In correspondence to these pathways, different morphologies of self-assembled protein molecules were detected by atomic force microscopy images also evidencing the prese…
The Fibril-associated Collagen IX Provides a Novel Mechanism for Cell Adhesion to Cartilaginous Matrix
2004
Collagen IX is the prototype fibril-associated collagen with interruptions in triple helix. In human cartilage it covers collagen fibrils, but its putative cellular receptors have been unknown. The reverse transcription-PCR analysis of human fetal tissues suggested that based on their distribution all four collagen receptor integrins, namely alpha1beta1, alpha2beta1, alpha10beta1, and alpha11beta1, are possible receptors for collagen IX. Furthermore primary chondrocytes and chondrosarcoma cells express the four integrins simultaneously. Chondrosarcoma cells, as well as Chinese hamster ovary cells transfected to express alpha1beta1, alpha2beta1, or alpha10beta1 integrin as their only collage…
Intramuscular Extracellular Matrix: Complex Environment of Muscle Cells
2002
KOVANEN, V. Intramuscular extracellular matrix: Complex environment of muscle cells. Exerc. Sport Sci. Rev., Vol. 30, No. 1, pp 20–25, 2002. Different collagen types among other extracellular matrix molecules, remodeling of the extracellular matrix with the aid of matrix metalloproteinases, and inte
A case report of pulmonary vein isolation performed in a patient with polysplenia and interrupted inferior vena cava
2021
Abstract Background Pulmonary vein isolation (PVI) has entrenched itself as one of the main approaches for the treatment of paroxysmal symptomatic atrial fibrillation (AF). Pulmonary vein isolation prevents focal triggers from pulmonary veins from initiating AF paroxysms. As standard—PVI is performed through the inferior vena cava (IVC) approach, through the femoral vein. However, there are conditions when this approach is not appropriate or is not available. Case summary We report a case of a 53-year-old male who was referred to Pauls Stradins Clinical University Hospital for PVI due to worsening AF. Due to the rare anatomical variant of the venous system, the standard approach to PVI coul…