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M C Jamur

Publications and source records attributed to M C Jamur.

17 recordsLinked to original sources
PubMed1998

Heparin potentiates in vivo neutrophil migration induced by IL-8.

Chemokine IL-8 attracts neutrophils by a haptotactic gradient, made possible by its interaction with proteoglycans of the extracellular matrix. Heparan sulfate, but not heparin, potentiates the attraction exerted in vitro by IL-8. In the present study we first confirmed this in vitro phenomenon, observing that IL-8 activity was potentiated 100% by heparan sulfate, but not by heparin. Then, we evaluated the interference of heparan sulfate or heparin on in vivo neutrophil migration induced by IL-8. The activity of rat IL-8 (3.5 microg/animal) preincubated with heparan sulfate (50 microg/animal) or heparin (77 microg/animal) was assayed on the rat dorsal air pouch. Contrary to in vitro experiments, heparin, but not heparan sulfate, potentiated the in vivo IL-8 activity two-fold. We investigated the relationship between this observation and that reported by others, that IL-8-induced migration depends on the presence of mast cells, which contain heparin-rich granules. We studied the neutrophil migration induced by IL-8 (3.5 microg/animal) into the rat peritoneal cavity depleted of mast cells. Neutrophil migration was reduced by 32% when compared to that observed in normal animals. The response of depleted rats was reconstituted by preincubation of IL-8 with heparin (77 microg/animal). These data suggest that heparin released from cytoplasmic granules may be the contribution of mast cells to IL-8-induced neutrophil migration.

Animals↗
PubMed1997

Immunocytochemical identification of immature rat peritoneal mast cells using a monoclonal antibody specific for rat mast cells.

The lack of immunological or morphological markers makes identification of immature mast cells difficult. In the present study we have used a rat mast cell specific monoclonal antibody (mAb AA4) to immunolabel mast cells during repopulation of the peritoneal cavity. Peritoneal cells were collected six days after injection of distilled water and examined by light and electron microscopy. mAb AA4 stained immature mast cells in various stages of maturation including a population of very immature mast cells that could not be identified using conventional staining methods. These cells had virtually no cytoplasmic granules and peripherally located lobated nuclei. Thus, immunolabeling with mAb AA4 has revealed a population of very immature mast cells not previously reported during repopulation of the peritoneal cavity.

Animals↗
PubMed1997

Mast cell maturation in young rats: a histofluorescence and cytochemical study.

Since they are not submitted to experimental alterations new-born rats are useful for the investigation of mast cell maturation and were therefore analysed in the present study. In the mesentery of new-born rats immature mast cells were present within and close to fat sheaths containing blood vessels. On day 15, mast cells were also found in mesentery windows and generally in a more advanced stage of maturation. On day 30, the distribution and maturation of mast cells were similar to those found in adult rats. In new-born rats, immature mast cells contained a few metachromatic granules, which showed a positive fluorescence after berberine sulfate staining for heparin and after exposure to paraformaldehyde for serotonin detection. Orthophthaldialdehyde-induced fluorescence for histamine demonstration was negative. On day 15, heparin and serotonin fluorescence were increased and histamine fluorescence became positive. Electron microscopically most mesentery immature mast cells of new-born rats had a well developed Golgi apparatus and rough endoplasmic reticulum, numerous mitochondria and an indented nucleus. The few cytoplasmic granules were large and some of them showed a positive trimetaphosphatase reaction in their periphery. On day 15, most mast cells were almost full of granules. On day 30, mast cells could not be distinguished from those in adult rats. These results show that mast cell maturation in young rats differs from that in adult animals after peritoneal distilled water injection.

Animals↗
PubMed1997

Immunomagnetic isolation of rat bone marrow-derived and peritoneal mast cells.

Mast cells are difficult to purify from heterogeneous cell populations and to preserve, especially for pre-embedding immunostaining at the ultrastructural level. We have developed a technique that permits the isolation of a pure population of mast cells suitable for immunocytochemical studies. A rat mast cell-specific monoclonal antibody (MAb AA4) conjugated to tosylactivated Dynabeads 450 was used to immunomagnetically separate mast cells from rat bone marrow and peritoneal cell suspensions. Approximately 85% of the mast cells were recovered in the positive population that comprised virtually pure mast cells. After microwave fixation, morphological examination showed that the cells were intact and retained their ultrastructural detail. Mast cells in all stages of maturation were immunolabeled with a panel of antibodies after immunomagnetic separation. The combination of immunomagnetic separation followed by immunostaining should prove useful for the study of mast cell maturation and for the characterization of other specific cell types that are present in tissues in only limited numbers.

Animals↗
PubMed1996

Binding of antibody to the gamma subunit of FCepsilonRI in rat basophilic leukemia cells results in morphological changes without inducing histamine release.

The high affinity IgE receptor on mast cells and basophils is composed of 3 subunits, alpha, beta and gamma. A polyclonal antibody was raised in rabbits to a 13 amino acid synthetic peptide corresponding to the amino terminal portion of the gamma subunit. The antiserum was screened using Western blots of solubilized RBL-2H3 cells and 125I goat anti-rabbit IgG. After purification of the serum on a protein G column, RBL-2H3 cells, mouse mast cells, and human basophils showed a doublet at 20 000 kDa. When 125I labeled, saponin-permeabilized cells were immunoprecipitated with the anti-gamma antibody, all 3 subunits of the IgE receptor complex coprecipitated. Furthermore, binding of the antibody to the cell surface did not induce histamine release. By immunofluorescence of fixed cells, the receptor was evenly distributed in the RBL-2H3 cells. Although no capping was observed when the cells were incubated with the antibody prior to fixation, the antibody did stimulate endocytosis when it was bound to the cells at 25 degrees C or at 37 degrees C, but not at 4 degrees C. Binding of the antibody to the RBL-2H3 cells also induced cell spreading and ruffling of the plasma membrane. The results of this study indicate that the gamma subunit of the high affinity IgE receptor may play a role in signal transduction.

Animals↗
PubMed1995

Microwave fixation improves antigenicity of glutaraldehyde-sensitive antigens while preserving ultrastructural detail.

Microwave fixation for electron microscopy has been used primarily for post-embedding immunocytochemistry. The present study examined the ability of microwave fixation to preserve the antigenicity of glutaraldehyde-sensitive antigens for pre-embedding immunocytochemistry. Five monoclonal antibodies (MAbs) directed against cell surface components of rat mast cells were tested. The MAbs failed to show any labeling of conventionally fixed rat bone marrow-derived mast cells even at glutaraldehyde concentrations as low as 0.1%. Strong staining of mast cell plasma membranes was seen when bone marrow was initially fixed with 2% formaldehyde and then refixed in 2% glutaraldehyde/2% formaldehyde after immunostaining. However, the ultrastructural preservation of the cells was poor. Antigenicity and morphological detail were both preserved when bone marrow was fixed in 0.05% glutaraldehyde/2% formaldehyde for 4 sec in a 550-W microwave oven. With this method, mast cells in various stages of maturation as well as cells that did not contain granules were immunoreactive. This method should prove useful with antigens from many different cell types that are sensitive to glutaraldehyde fixation.

Animals↗
PubMed1993

Ultrastructural similarity between bat and human mast cell secretory granules.

Mast cells in the tongue of the bat (Artibeus lituratus) show a well-developed Golgi area and abundant mitochondria in the granule-free perinuclear cytoplasm. Rough endoplasmic reticulum profiles, free ribosomes, mitochondria, bundles of filaments and a great number of secretory granules are found throughout the remaining cytoplasm. The granules, of various shapes and sizes, are simple containing an electron-dense, homogeneous matrix, coarse particles or cylindrical scrolls, or combinations (cylindrical scrolls with either electron-dense, homogeneous matrix or coarse particle contents). Up to now, scroll-containing granules have been considered to be a unique feature of human mast cells.

Animals↗
PubMed1990

Cytochemical demonstration of acid phosphatase, trimetaphosphatase and basic protein in rat peritoneal mast cells during 48/80 induced exocytosis.

Acid phosphatase (AcP-A), trimetaphosphatase (TmP-A) activities and basic protein reaction were cytochemically studied in rat peritoneal mast cells 15 minutes after stimulation by compound 48/80. The AcPase reaction was positive in slightly altered granules, but negative in those more intensely altered, and also in unaltered granules. The TmP-A reaction was negative in altered granules and positive in a few unaltered granules. These results suggest that mast cells have two populations of granules, one, comprising most granules, is AcP-A positive and is exocytosed. The other, smaller, is TmP-A positive, and is not exocytosed. Intact granules gave a strong positive reaction with amoniacal silver nitrate (AS), which detects basic protein. This reaction decreased in intensity with increasing granule alteration.

Acid Anhydride Hydrolases↗
PubMed1986

Ultrastructural and cytochemical studies of acid phosphatase and trimetaphosphatase in rat peritoneal mast cells developing in vivo.

The ultrastructural and cytochemical features of peritoneal mast cells of the rat were studied. Immature mast cells show specific cytoplasmic granules of different sizes, the smaller ones localized in the Golgi region. The rough endoplasmic reticulum and Golgi apparatus are well developed, and mitochondria are numerous. Nuclei show deep indentations. Acid phosphatase is present in the Golgi saccules, in GERL (Golgi apparatus-endoplasmic reticulum-lysosome) and in some small granules. It is not present in mature granules. Trimetaphosphatase is present in the Golgi saccules, in GERL, in most immature granules and in some mature granules. These enzymes appear to be transported and packaged into granules by the Golgi apparatus, suggesting that the specific mast cell granules may be a form of lysosome. The results of this study are consistent with the hypothesis that peritoneal mast cells may be derived from macrophage-like precursors.

Acid Anhydride Hydrolases↗
PubMed1986

Maturation of adult rat peritoneal and mesenteric mast cells. A morphological and histofluorescence study.

Repopulation and maturation of rat mesenteric and peritoneal mast cells were studied after mast cell depletion by intraperitoneal injection of distilled water. Immature mast cells were first identified in the mesentery and peritoneal fluid 5 and 6 days, respectively, after water injection. The most immature mast cells that could be identified contained a few orthochromatic granules. Upon maturation, the granules became metachromatic and increased in size and number. Heparin, revealed by toluidine blue staining and berberine sulfate fluorescence, appeared simultaneously with orthophthaldialdehyde (OPT)-induced histamine fluorescence. Paraformaldehyde-induced serotonin fluorescence appeared somewhat later. Repopulation of mesentery and peritoneal fluid by mast cells seemed to be independent of each other and to occur from undifferentiated precursor cells.

Animals↗
PubMed1983

[Nemaline myopathy: report of a case with a histochemical and electron microscopy study].

Report of a case of a male child, with hypotonia since birth, along with severe feeding difficulties due to lack of swallowing, that resulted in a permanent gastrostomy. Despite the delayed motor development, he had a normal intelligence. An electromyography was suggestive of primary muscle involvement. A fresh-frozen muscle biopsy stained by the modified Gomori trichrome and processed by histochemistry and electron microscopy presented the typical nemaline rods and deficiency of type II muscle fibers. It is made a brief revision about the clinical symptoms, origin and pathogenesis of nemaline bodies. The case reported probably represents a nemaline myopathy, of the congenital type.

Deglutition Disorders↗