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Local Damage (local + damage)
Selected AbstractsUse of collision shear walls to minimize seismic separation and to protect adjacent buildings from collapse due to earthquake-induced poundingEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 12 2008S. A. Anagnostopoulos Abstract The use of collision shear walls (bumper-type), acting transversely to the side subject to pounding, as a measure to minimize damage of reinforced concrete buildings in contact, is investigated using 5-story building models. The buildings were designed according to the Greek anti-seismic and reinforced concrete design codes. Owing to story height differences potential pounding in case of an earthquake will occur between floor slabs, a case specifically chosen because this is when pounding can turn out to be catastrophic. The investigation is carried out using nonlinear dynamic analyses for a real earthquake motion and also a simplified solution for a triangular dynamic force of short duration, comparable to the forces caused by pounding. For such analyses, nonlinear, prismatic beam,column elements are used and the effects of pounding are expressed in terms of changes in rotational ductility factors of the building elements. The local effects of pounding on the collision shear walls are investigated using a detailed nonlinear finite element model of the shear walls and results are expressed in terms of induced stresses. It is found that pounding will cause instantaneous acceleration pulses in the colliding buildings and will somewhat increase ductility demands in the members of the top floor, but all within tolerable limits. At the same time the collision walls will suffer repairable local damage at the points of contact, but will effectively protect both buildings from collapse, which could occur if columns were in the place of the walls. Copyright © 2008 John Wiley & Sons, Ltd. [source] Histopathology, immunohistochemistry and ultrastructure of the intestine of Leuciscus cephalus (L.) naturally infected with Pomphorhynchus laevis (Acanthocephala)JOURNAL OF FISH DISEASES, Issue 1 2002B S Dezfuli The histopathology, immunohistochemistry and ultrastructure of the alimentary canal of chub, Leuciscus cephalus (L.), from the River Brenta, naturally infected with the acanthocephalan Pomphorhynchus laevis Müller, 1776, was studied and described. Of 62 chub examined, 54 (87%) were infected with P. laevis; the intensity of infection ranged from five to 130 parasites per host, and a density of 8 P. laevis per cm2 was common. Examination of histological material of infected chub revealed that both male and female acanthocephalans deeply penetrated all layers of the gut wall by means of their slender neck, bulb and proboscis. As a result, a capsule was formed around the bulb and proboscis on the external surface of the host intestine. In parasitized chub, four main types of reaction against the body of the acanthocephalan were recognized. Pomphorhynchus laevis caused local damage to the intestinal wall, eliciting catarrhal-erosive enteritis in the lumen and a fibroblastic-collagenous and fibro-epithelioid encapsulation in its thickness with tissue zonation according to the depth of parasite penetration. Furthermore, eosinophilic granular cells (EGC) within the inflammatory tissue were identified by immunohistochemical methods and transmission electron microscopy. [source] Regional-specific regulation of BDNF and trkB correlates with nigral dopaminergic cell sprouting following unilateral nigrostriatal axotomyJOURNAL OF NEUROSCIENCE RESEARCH, Issue 9 2008J. T. García Navia Abstract Axotomy is a powerful stimulus of axon growth and plastic changes. We investigated the potential role of BDNF/trkB signaling in the sprouting of dopaminergic nigral axons in response to axotomy of the medial forebrain bundle. Tyrosine hydroxylase immunohistochemistry revealed the existence of sprouting mechanisms in the axotomized substantia nigra (SN). Time-course changes of trkB mRNA expression demonstrated a robust increase in an area projecting from the rostral tip of the SN to the glial scar, which coincided with evidence of nigral dopaminergic sprouting. In addition, we found an early loss of this messenger in areas related to the knife cut, which recovered by 7 days postlesion. TrkB down-regulation appeared to be associated to the lesion-induced local damage, as it was restricted to an area showing Fluoro-Jade B, and TUNEL positive cells. In trkB-depleted areas, an inverse correlation between mRNA expressions of BDNF and trkB was apparent. Specific induction of BDNF mRNA was mostly seen in border of areas devoid of trkB mRNA. In contrast, in the areas exhibiting trkB mRNA expression, no BDNF mRNA was detected. We suggest that trkB levels could be a determinant element in regulating BDNF expression. Finally, the search for molecules involved in either promoting or inhibiting axonal growth, demonstrated up-regulation of GAP-43 and Nogo-A mRNA at sites close to the knife transections as early as 1 day postlesion. However, overall, Nogo-A induction was more robust than that seen for GAP-43. © 2008 Wiley-Liss, Inc. [source] Piezospectroscopic Analysis of Interface Debonding in Thermal Barrier CoatingsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2000Xiao Peng One of the principal modes by which electron-beam-evaporated thermal barrier coatings fail is via the nucleation of local regions of debonding, which grow and link together until reaching a critically sized flaw for spontaneous buckling and spalling. This progressive-failure mode is used as a basis for analyzing the changes that can occur in photostimulated luminescence spectra that have been recorded from the thermally grown oxide. This process also provides a basis for the quantitative determination of the extent of local damage prior to spalling from an analysis of the shape of the luminescence spectra. [source] Complementary roles of platelets and coagulation in thrombus formation on plaques acutely ruptured by targeted ultrasound treatment: a novel intravital modelJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 1 2009M. J. E. KUIJPERS Summary.,Background:,Atherothrombosis is a major cause of cardiovascular events. However, animal models to study this process are scarce. Objectives:,We describe the first murine model of acute thrombus formation upon plaque rupture to study atherothrombosis by intravital fluorescence microscopy. Methods:,Localized rupture of an atherosclerotic plaque in a carotid artery from Apoe,/, mice was induced in vivo using ultrasound. Rupture of the plaque and formation of localized thrombi were verified by two-photon laser scanning microscopy (TPLSM) in isolated arteries, and by immunohistochemistry. The thrombotic reaction was quantified by intravital fluorescence microscopy. Results:,Inspection of the ultrasound-treated plaques by histochemistry and TPLSM demonstrated local damage, collagen exposure, luminal thrombus formation as well as intra-plaque intrusion of erythrocytes and fibrin. Ultrasound treatment of healthy carotid arteries resulted in endothelial damage and limited platelet adhesion. Real-time intravital fluorescence microscopy demonstrated rapid platelet deposition on plaques and formation of a single thrombus that remained subocclusive. The thrombotic process was antagonized by thrombin inhibition, or by blocking of collagen or adenosine diphosphate receptor pathways. Multiple thrombi were formed in 70% of mice lacking CD40L. Conclusions:,Targeted rupture of murine plaques results in collagen exposure and non-occlusive thrombus formation. The thrombotic process relies on platelet activation as well as on thrombin generation and coagulation, and is sensitive to established and novel antithrombotic medication. This model provides new possibilities to study atherothrombosis in vivo. [source] Review: Role of developmental inflammation and blood,brain barrier dysfunction in neurodevelopmental and neurodegenerative diseasesNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 2 2009H. B. Stolp The causes of most neurological disorders are not fully understood. Inflammation and blood,brain barrier dysfunction appear to play major roles in the pathology of these diseases. Inflammatory insults that occur during brain development may have widespread effects later in life for a spectrum of neurological disorders. In this review, a new hypothesis suggesting a mechanistic link between inflammation and blood,brain barrier function (integrity), which is universally important in both neurodevelopmental and neurodegerative diseases, is proposed. The role of inflammation and the blood,brain barrier will be discussed in cerebral palsy, schizophrenia, Parkinson's disease, Alzheimer's disease and multiple sclerosis, conditions where both inflammation and blood,brain barrier dysfunction occur either during initiation and/or progression of the disease. We suggest that breakdown of normal blood,brain barrier function resulting in a short-lasting influx of blood-born molecules, in particular plasma proteins, may cause local damage, such as reduction of brain white matter observed in some newborn babies, but may also be the mechanism behind some neurodegenerative diseases related to underlying brain damage and long-term changes in barrier properties. [source] Anti-snake venom properties of Schizolobium parahyba (Caesalpinoideae) aqueous leaves extractPHYTOTHERAPY RESEARCH, Issue 7 2008Mirian M. Mendes Abstract Many medicinal plants have been recommended for the treatment of snakebites. The aqueous extracts prepared from the leaves of Schizolobium parahyba (a plant found in Mata Atlantica in Southeastern Brazil) were assayed for their ability to inhibit some enzymatic and biological activities induced by Bothrops pauloensis and Crotalus durissus terrificus venoms as well as by their isolated toxins neuwiedase (metalloproteinase), BnSP-7 (basic Lys49 PLA2) and CB (PLA2 from crotoxin complex). Phospholipase A2, coagulant, fibrinogenolytic, hemorrhagic and myotoxic activities induced by B. pauloensis and C. d. terrificus venoms, as well as by their isolated toxins were significantly inhibited when different amounts of S. parahyba were incubated previously with these venoms and toxins before assays. However, when S. parahyba was administered at the same route as the venoms or toxins injections, the tissue local damage, such as hemorrhage and myotoxicity was only partially inhibited. The study also evaluated the inhibitory effect of S. parahyba upon the spreading of venom proteins from the injected area into the systemic circulation. The neutralization of systemic alterations induced by i.m. injection of B. pauloensis venom was evaluated by measuring platelet and plasma fibrinogen levels which were significantly maintained when S. parahyba extract inoculation occurred at the same route after B. pauloensis venom injection. In conclusion, the observations confirmed that the aqueous extract of S. parahyba possesses potent snake venom neutralizing properties. It may be used as an alternative treatment to serum therapy and as a rich source of potential inhibitors of toxins involved in several physiopathological human and animal diseases. Copyright © 2008 John Wiley & Sons, Ltd. [source] Evaluation of Process-Induced Dimensional Changes in the Membrane Structure of Biological Cells Using Impedance MeasurementBIOTECHNOLOGY PROGRESS, Issue 3 2002Alexander Angersbach The impact of high intensity electric field pulses, high hydrostatic pressure, and freezing-thawing on local structural changes of the membrane was determined for potato, sugar beet tissue, and yeast suspensions. On the basis of the electrophysical model of cell systems in biological tissues and suspensions, a method was derived for determining the extent of local damage of cell membranes. The method was characterized by an accurate and rapid on-line determination of frequency-dependent electrical conductivity properties from which information on microscopic events on cellular level may be deduced. Evaluation was based on the measurement of the relative change in the sampleapos;s impedance at characteristically low ( fl) and high ( fh) frequencies within the ,-dispersion range. For plant and animal cells the characteristic frequencies were fl , 5 kHz and fh > 5 MHz and for yeast cells in the range fl , 50 kHz and fh > 25 MHz. The observed phenomena were complex. The identification of the underlying mechanisms required consideration of the time-dependent nature of the processing effects and stress reactions of the biological systems, which ranged from seconds to several hours. A very low but significantly detectable membrane damage (0.004% of the total area) was found after high hydrostatic pressure treatment of potato tissue at 200 MPa. The membrane rupture in plant tissue cells was higher after freezing and subsequent thawing (0.9% of total area for potato cells and 0.05,0.07% for sugar beet cells determined immediately after thawing), which increased substantially during the next 2 h. [source] | |||||||||||||