Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.6.4 (chondroitinase)
 2,039 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Pacinian corpuscle consists of a sensory axon terminal that is enveloped by two different structures, the inner core and the capsule. Since proteoglycans are extremely water soluble and are extracted by conventional methods for electron microscopy, the current picture of the structural composition of the extracellular matrix in the inner core and the capsule of the Pacinian corpuscle is incomplete. To study the structural composition of the extracellular matrix of the Pacinian corpuscles, cationic dyes (ruthenium red, alcian blue, acridine orange) and tannic acid were applied simultaneously with the aldehyde fixation. The interosseal Pacinian corpuscles of the rat were fixed either in 2% formaldehyde and 1.5% glutaraldehyde, with the addition of one of these cationic dyes or, in Zamboni's fixative, with tannic acid added. The cationic dyes and tannic acid revealed a different structural pattern of proteoglycans in the extracellular matrix in the inner core and in the capsule of the rat Pacinian corpuscles. The inner core surrounding the sensory axon terminal is a compartment containing proteoglycans that were distributed not only in the extracellular matrix but also in the cytoplasm of the lamellae. In addition, this excitable domain was separated from the capsular fluid by a thick layer of proteoglycans on its surface. An enlarged interlamellar space of the capsule contained large amounts of proteoglycans that were removed by digestion with chondroitinase-ABC. Ruthenium red and alcian blue provided only electron dense granules, probably corresponding to collapsed monomeric proteoglycan molecules. Acridine orange and tannic acid preserved proteoglycans very well and made it possible to visualize them as "bottlebrush" structures in the electron microscope. These results show that the inner core and the capsule of rat Pacinian corpuscles have different structural patterns of proteoglycans, which are probably involved in different functions.
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PMID:The extracellular matrix of rat pacinian corpuscles: an analysis of its fine structure. 1059 65

In situ binding of (chimeric) proteins to tissue sections is a widely used method to identify ligands and their localization. Many different protocols for the fixation of frozen tissue sections are used for in situ binding studies. We report the effects of different fixation protocols on the binding pattern observed using in situ binding of an L-selectin-IgM chimeric protein to both rat lymph node and kidney tissue sections. L-selectin is a C-type lectin, expressed on leukocytes and is involved in both lymphocyte homing and migration upon inflammation. We show that different in situ binding patterns in rat kidney are observed using different fixation protocols, including glutaraldehyde, methanol, formaldehyde and acetone fixation. The observed staining is specific, as it can be blocked in the presence of EGTA, an L-selectin blocking antibody or by ligand competition. Enzymatic pre-treatment of the tissue sections using sialidase, heparitinase I or chondroitinase ABC has differential effects on in situ binding depending on tissue type and fixation protocol. These data indicate that special attention should be paid in choosing a fixation protocol for in situ binding studies, especially when using lectins. This could prevent biologically relevant ligands remaining undetected or wrong conclusions being drawn based on the localization of observed binding.
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PMID:Effect of fixation protocols on in situ detection of L-selectin ligands. 1584 5

The aim of this study was to investigate the relationship between proteoglycans (PGs) and collagen fibrils at the early mineralization process of mantle dentin. Ten first molar dental germs of rats were removed and fixed in glutaraldehyde/formaldehyde in cacodylate buffer and post-fixed in osmium tetroxide. The samples were dehydrated and embedded in epoxy resin. Ultrathin sections were contrasted and analyzed in TEM before and after treatment with EDTA, chondroitinases AC and ABC. After EDTA treatment, a electrondense substance associated with collagen fibril was removed, and did not stain again. A high magnification of these areas showed globular structures with 15 nm diameter surrounding collagen fibrils. In advanced mineralization areas, collagen fibrils showed a banded pattern and at high magnification the fibrils presented a light 10 nm ring inside and a dark 10 nm ring outside. After chondroitinase treatment, the electrondense substance associated with collagen fibrils was removed, showing a banded pattern of clear and dark areas along them. From morphological data, the authors proposed a model of interaction between PGs and collagen fibrils, where glicosaminoglycans chains are inside the fibrils, while the protein core remains outside. That stereochemical arrangement would start the crystal nucleation.
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PMID:A model of the early mineralization process of mantle dentin. 1699 43