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Pathological biomineralization from human aortic and mitral valve stenosis.
No full textSamples were collected as surgical waste from patients undergoing valvular replacement because of severe aortic (n=6) and mitral (n=2) stenosis. Pathological mineral formations have been investigated with XRPD and SEM-EDS, both in high and in low vacuum conditions. Samples were not coated because of metallic coating artifacts.The a cell parameters were found to be smaller than the a parameter of human dental enamel apatite, while the c parameters were greater. High resolution images show a complex relationship between inorganic component and organic matrix as well as particular morphologies of the pathogenic biomineralization. Bioapatite appears as lamellar crystals, globular aggregated and massive; at high magnification it appears to be constituted of spherical particles of variable size. Bioapatite morphology observed in this study appears to be different from biogenic calcium phosphate crystals and from inorganically produced counterparts. The small spheres could be considered as nanobacterial-like structures (?). This attractive hypothesis has not been confirmed yet
Myosin changes in hypertrophied human atrial and ventricular myocardium. A correlated immunofluorescence and quantitative immunochemical study on serial cryosections.
No full textTwo antigenically distinct types of myosin heavy chain, referred to as alpha and beta, have been identified in autoptic and bioptic specimens of human heart using specific antimyosin antibodies. By immunofluorescence heavy chain alpha was present in all atrial myocytes and in a variable number of ventricular myocytes. Heavy chain beta was present in all ventricular myocytes and in a number of atrial myocytes. Ventricular hypertrophy in patients with aortic stenosis, systemic hypertension or tetralogy of Fallot was characterized by an almost complete absence of fibres reactive with anti-alpha. A striking decrease in alpha chain reactivity and a parallel increase in beta chain reactivity was apparent in the hypertrophied left atria of patients with mitral stenosis. To quantify these myosin changes a novel procedure was developed whereby myosin was extracted from single cryosections serial to those processed for immunofluorescence and the relative amount of alpha and beta heavy chain was determined by enzyme immunoassay. Heavy chain alpha was less than 5% in most normal ventricular specimens and disappeared completely under the effect of pressure overload. On the other hand heavy chain beta was generally undetectable in the left atrial myocardium but increased up to 90% in biopsies of hypertrophied atria
Calcification of the human heart valves: a mineralogical approach
No full textNormal physiologic processes result in development of mineralized tissue. Bones and tooth enamel are the main example of biominerals. Pathologic processes lead to calcification of the atherosclerotic plaques, kidney and salivary stones and other pathologic deposits. Most of these seem to be constituted from a mixture of calcium phosphate phases but their formation mechanisms are not completely known. In cardiac pathology, calcification of heart valves can be advanced by a congenital malformation or an infectious process or related to the senile degeneration. Pathological mineral deposits occurring in human cardiac valves were studied using Polarizing Microscopy, Scanning Electron Microscopy (SEM-EDS), Electron Microprobe (EMPA), X-Ray Powders Diffraction (XRPD), Infrared Spectroscopy (FTIR). Samples were obtained as surgical waste from thirty patients undergoing valvular replacement in case of severe aortic and mitral stenoses. The experimental results showed that the mineral phase grown in human cardiac valves is a calcium phosphate with poor crystallinity. It develops as nodules in the organic matrix. The FT-IR spectra may be used to infer the presence of carbonate group. The carbonate bands in the infrared spectra have a saw-tooth profile similar to sample PC18, a synthetic type A-B CAp but in samples of aortic valves a-parameter is smaller and the c-parameter is greater than those of PC18 [i.e. TV12 a=9.4165(8) Å, c= 6.8951(7) Å; PC18 a=9.4803(3) Å, c=6.8853(3) Å] probably due to substitutional carbonate groups in phosphate positions which cause a shrinkage in the a-parameter. Pathological phase investigated can be considered a bioapatite as the inorganic component of bone and tooth enamel, even if it possesses unusual morphologies for a calcium phosphate and a Ca/P ratio unlike that of normal mineralized tissue
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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