1,721,121 research outputs found
Use of freeze-drying technology for the study of renal biopsies.
No full textAdequate handling of renal biopsies requires processing for light and electron
microscopy, as well as for immunohistochemical study. Problems of adequate
sampling are frequently encountered, and tissue size can be insufficient, since
morphologic examination requires chemical fixation, while immunofluorescence
study is currently performed on snap-frozen, cryostat-cut tissue. The application
of freeze-drying technology on 20 renal needle biopsies has been investigated to
assess the feasibility and reliability of the technique as a routine diagnostic
tool in renal pathology. Morphologic as well as immunohistochemical studies were
performed on freeze-dried, paraffin-embedded specimens, including
immunofluorescence and PAP techniques to detect immunoglobulins, complement
fractions, fibrinogen, collagen types, and laminin. Our results showed good
preservation of tissue morphology, similar to standard formalin fixation.
Moreover, absence of diffusion artifacts and intensity of immunohistochemical
reactions were comparable to what is obtained with cryostat sections. We
therefore suggest that freeze-drying before paraffin embedding is, at least for
diagnostic purposes, preferable to formalin fixation; unfixed, cryostat-cut
sections can still be informative and should be used whenever tissue is available
in selected cases, and/or in experimental work
Physico-chemical analysis of resorcin-fuchsin reagents and its relevance to staining quality of elastic fibres.
No full textThree Weigert's resorcin-fuchsin reagents for elastic fibres were prepared by
using different lots of basic fucsin and by preparing the staining solutions with
ferric chloride or ferric perchlorate. The solutions were analyzed by
spectrophotometry, thin layer chromatography (TLC) and spectrofluorimetry. Their
ability to stain elastic fibres was tested on several human tissue. The strongest
stain and faintest background were obtained with the fuchsin-chloride reagent,
which showed the most significant reduction of the absorption at 575 nm by
spectrofluorimetry, associated with an increased absorption at 510 nm with
respect to the other stains. The results showed that physico-chemical analysis
can represent a reliable, although empirical, way to predict the usefulness of a
resorcin-fuchsin reagent for histological work
Collagen VII expression in glomerular sclerosis
No full textGlomerular sclerosis is the final stage of a variety of kidney diseases and matrix molecules not normally expressed in the extracellular matrix are synthesized and accumulate during the sclerotic process. Collagen type VII is the major component of the anchoring fibrils at the dermal-epidermal junction, but it is usually not present in normal glomeruli. The aim of this study was to investigate whether this type of fibrillary collagen, different from types I and III, is expressed in chronically diseased glomerular extracellular matrix. The presence and distribution of collagen VII have been examined in 50 renal biopsies by indirect immunofluorescence staining, standard electron microscopy, and immuno-electron microscopy. In selected cases, collagen VII mRNA expression was also measured by RT-PCR on isolated glomeruli. Cases included focal segmental glomerulosclerosis, minimal change disease, membranous glomerulonephritis, IgA nephropathy, SLE nephritis, diabetic glomerulosclerosis, ischaemic renal disease, extracapillary glomerulonephritis, and end-stage renal disease. Collagen VII protein and mRNA expression was absent or present in trace amounts in normal kidneys or in disorders with only a mild increase of mesangial matrix, without scarring of the tuft. Maximal expression was evident in the presence of adhesions between the glomerular tuft and Bowman's capsule or fibrous crescents. The results showed that collagen VII is actively synthesized and laid down in areas of glomerular and/or tubular scarring, irrespective of the underlying disease, confirming the de novo expression of fibrillary collagens in diseased renal extracellular matrix. The appearance of an anchoring collagen may be a response to support mechanical stress and it takes part in the process of cell proliferation and tissue repair. Copyright (C) 2001 John Wiley & Sons, Ltd
Transforming growth factor-beta enhances adhesion of melanoma cells to the endothelium in vitro
No full textMelanoma invasion requires migration through the vascular barrier. An early event in this process is the adhesion of metastatic cells to the endothelium. To elucidate the role of TGF-beta in the regulation of this process, human melanoma SK-MEL24 cells were labelled with +AFs-5'-H-3+AF0--thymidine and co-cultured with bovine pulmonary artery endothelial-cell monolayers. Radioactivity was assumed to be proportional to the number of SK-MEL24 cells bound to the endothelium. A low number of melanoma cells adhered to endothelial cells in a time-related manner. Pretreatment for 24 hr with 0.001 to 10 ng/ml TGF-beta(1) or TGF-beta(2) of both cell types enhanced melanoma-endothelium adhesion in a dose-dependent manner. Both melanoma and endothelial cells expressed RI-and RII-type TGF-beta receptors. The effect of TGF-beta was abolished by co-incubation with the proteoglycan decorin. Conditioned media from melanoma-endothelium co-cultures contained latent TGF-beta and failed to affect cell-cell adhesion. However, activation of TGF-beta by heating the medium or reducing the pH, increased melanoma-endothelium adhesion to an extent similar to that of the TGF-beta administered to the cultures. Zimography demonstrated that both cell types expressed urokinase-type plasminogen activator (uPA). Addition of plasminogen to the co-cultures, which was likely to be activated to plasmin by uPA, resulted in activation of TGF-beta and parallel stimulation of melanoma-endothelium adhesion. In conclusion, TGF-beta may enhance adhesion of melanoma cells to the endothelium, playing a relevant autocrine/paracrine role in the progression of invasive melanoma. (C) 1997 Wiley-Liss, Inc
Prognostic value of glomerular collagen IV immunofluorescence studies in male patients with X-linked Alport syndrome.
No full textIndagine di correlazioni anatomo cliniche in 22 pazienti con sindrome di alport x-linked per valutare il significato prognostico della espressione del collagene di tipo IV nella membrana basale dei glomerul
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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