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Biomedical subjects

I Hammel

Publications and source records attributed to I Hammel.

At least 37 records · Page 2Linked to original sources
PubMed1995

An histochemical approach to characterization of anionic constituents in mast cell secretory granules.

We used cationized colloidal gold in order to investigate the distribution of anionic sites in different secretory granules of rat and mouse mast cells. The localization of the anionic sites was performed by post-embedding labeling of thin sections of rat peritoneal cells or mouse skin tissue, fixed in Karnovsky's fixative and OsO4, and embedded in Araldite or LR white, respectively. In all cases anionic sites were demonstrated with a high density variation depending on cell type. In all mast cell secretory granules we have observed the highest density (ca. 500-900 gold particles/microns2), while in other peritoneal cell granules it was about 10 times less (ca. 40-80 gold particles/microns2). Pretreatment of the LR white sections with heparinase I and III resulted in a reduction of 97% and 72%, respectively, in the binding of the gold particles to the granules, indicating that the majority of the gold binding reactivity is due to heparin. Correlation of section profile area with labeling density revealed that the smaller granules were significantly more labeled when compared to the larger profiles. On the basis of these observations it seems that a post-translational change (mainly sulfation of heparin) of secretory content influences the granule anionic charge and thus may affect the intragranule buffer capacity.

Animals↗
PubMed1995

The effect of lysosomal storage diseases on secretory cells: an ultrastructural study of pancreas as an example.

The lysosome is the disposal and recycling center of eukaryotic cells. The pancreas is an exocrine and endocrine organ. It contains different cell types secreting enzymes, hormones, ions and fluid. The purpose of this study was to demonstrate that the manifestation of the disease in individual cells depends on the expression of the defected gene within the function of the cells. We have thus compared the ultrastructural features of normal pancreas to pancreas affected by eleven different lysosomal storage diseases in human, cats, dogs and mice. The diseases studied include GM1- and GM2- gangliosidosis, galactosialidosis, alpha-mannosidosis, mucopolysaccharidosis-I (MPS-I), mucopolysaccharidosis-VI (MPS-VI), mucopolysaccharidosis-VII (MPS-VII), mucolipidosis-IV (ML-IV), Niemann-Pick C, neuronal ceroid-lipofuscinosis, and an undefined glycolipid storage disease. We demonstrated that morphological changes are seen in some pancreatic cell types but not in others, even though the genetic defect occurs in all cell types. Furthermore, we identified and characterized primary and secondary changes in affected cells. The primary changes include presence of numerous and/or enlarged secondary lysosomes laden with partially degraded substrates. The secondary changes were associated with an abnormal formation and maturation of zymogen or secretory granules. The mechanisms contributing to the secondary changes are thought to be associated with altered synthesis of various constituents of these granules.

Animals↗
PubMed1994

Cytoplasmic granule formation in mouse pancreatic acinar cells. Evidence for formation of immature granules (condensing vacuoles) by aggregation and fusion of progranules of unit size, and for reductions in membrane surface area and immature granule volume during granule maturation.

We used a computer-assisted morphometry approach to analyze quantitatively the process of cytoplasmic granule formation in mouse pancreatic acinar cells stimulated with pilocarpine to induce secretion. Our findings suggest that each condensing vacuole/immature granule of pancreatic acinar cells is formed by the progressive aggregation of 106 to 128 "unit progranules" of narrowly fixed volume, define a range of 7.7 to 9.2 for the factor of volume condensation between the largest immature granules and the mature unit granule, and predict that the formation of a single mature unit granule by the aggregation and fusion of unit progranules involves a net reduction of at least 95% in the amount of membrane surface area associated with these structures.

Animals↗
PubMed1994

Age-related basement membrane thickening of the vocal cords in sudden infant death syndrome (SIDS).

Sudden infant death syndrome (SIDS) remains the leading cause of death in the Western world among infants between the ages of 1 month to 1 year. The diagnosis can only be established at autopsy, at which time no obvious or recognizable pathology is evident. A correlation between thickening of the basement membrane of the true vocal cords and the victim's age was observed in all 51 larynges examined, whereas no such finding was detected in 82 larynges of infants who died of other causes. Thus, the data support the authors' previous morphological results suggesting the use of basement membrane thickening as a marker of positive diagnosis of SIDS at autopsy. The possibility that an immune process may be associated with this syndrome merits further investigation and could prove to be of great importance.

Age Factors↗
PubMed1994

Histochemical study of the blue autofluorescence of collagen in oral irritation fibroma: effects of age of patients and of the duration of lesions.

The intensity of the autofluorescence of collagen was measured in 27 irritation fibromata of the buccal mucosa and 13 of the lip. The intensity of fluorescence correlated positively with the duration of the lesion. The fluorescence intensity also increased with the patients' age. The present observations show that in irritation fibromata of buccal and lip mucosae, the intensity of blue autofluorescence of the collagen increases with duration of the lesions and with the age of patients.

Adolescent↗
PubMed1994

Mast cell and basophil development.

Mast cells and basophils express certain remarkable similarities in mediator content, histochemical characteristics, and function. Yet a large body of evidence now indicates that the mast cell and basophil lineages are distinct. Stem cell factor, the ligand for the receptor encoded by c-kit, is a major growth factor for mast cells in both rodent and primate species, and can modulate mast cell secretory function. Moreover, abnormalities affecting the stem cell factor receptor or stem cell factor might contribute to some cases of mastocytosis or mast cell neoplasms. By contrast, basophils can develop independently of stem cell factor, and are not as sensitive as mast cells to the effects of stem cell factor on mediator secretion. In addition, the cytokine interleukin-3 greatly augments the production of human basophils, but has little or no growth promoting activity for human mast cells.

Animals↗
PubMed1993

Theoretical considerations on the formation of secretory granules in the rat pancreas.

Rat pancreatic zymogen granule sizes were determined by analysis of electron micrographs of the pancreas from adult and newborn rats. Areas of granule profiles were measured and converted to equivalent volumes. Histograms of the equivalent volumes showed integral multimodal distributions which were evaluated for goodness of fit with two models, unit addition and random fusion. Previous analyses of zymogen granule size distributions have failed to recognize the multimodality we have observed. Distributions of equivalent volumes for the two models were developed using Monte Carlo simulation. In the case of the granules from the newborn rats, the distribution of granule sizes gave a better fit with the random fusion model, whereas the granules from the adult rats had distributions with a better fit to the unit granule addition model. The estimated unit granule sizes for the two different ages were the same. Both unit addition and random fusion models propose that following formation of secretory granules from Golgi-derived material, the granules fuse with one another to create a wide dispersion of granule sizes. The present results extend the evidence for fusional growth of secretory granules, originally developed for the mast cell, to the zymogen granules of pancreas. All normal cells previously studied have yielded secretory granule distributions most consistent with unit addition. The basis for the expression of random fusion in the newborn rather than the more usual unit addition is not known.

Aging↗
PubMed1993

Ultrastructure of human dermal mast cells in 29 different lysosomal storage diseases.

The effect of lysosomal storage diseases on the ultrastructure of human mast cells has not previously been reported. Indeed, there has been little published evidence indicating that mast cells contain typical lysosomes. However, mast cell cytoplasmic granules contain hydrolases similar to those found in lysosomes, but which differ from lysosomal hydrolases in exhibiting optimal activity at higher pH. We therefore examined by transmission electron microscopy the dermal mast cells in 58 biopsies of patients exhibiting 1 of 29 different lysosomal storage diseases. We found mast cells containing abnormal lysosomes in 16 of these disorders. In 6 of these 16 diseases, the mast cells' cytoplasmic granules appeared normal. These observations indicate that human mast cells can contain lysosomes, and provide evidence that the enzymes affected by lysosomal storage diseases are active in mast cells.

Biopsy↗
PubMed1993

Characteristics of palatal wound healing in desalivated rats.

The healing of excisional wounds in the palate of desalivated rats was evaluated. Experimental rats became desalivated after extirpation of the submandibular and sublingual glands and ligation of the parotid ducts. Small or large circular wounds, 3 or 5 mm in diameter, were produced in the palate. The wound area, area of inflammation, area of connective tissue formation and the number of myofibroblasts were determined at 0, 3, 7, 14, 21 and 28 days after surgery. The area of the small wound (3 mm) was similar in experimental and control groups; however, the area of the large wound (5 mm) was greater in the experimental group (p < 0.05-0.01). The area of inflammation was greater in the experimental group with small or large wounds (p < 0.05-0.01). Connective tissue formation was less (p < 0.01) in desalivated rats with a small wound at day 14 and with a large wound at days 21 and 28. There were fewer myofibroblasts in the large wound of desalivated rats (p < 0.01) than in controls between days 3 and 14. The results indicate that palatal wound healing is delayed in desalivated rats and that larger wounds are more sensitive to desalivation than smaller wounds.

Animals↗
PubMed1992

Dissociation between release and gene expression of gonadotropin alpha-subunit in gonadotropin-releasing hormone-stimulated alpha T3-1 cell line.

The alpha T3-1 cell line which was derived by targeted tumorigenesis in transgenic mice [Windle et al. (1990) Mol. Endocrinol. 4, 597-603] possesses high-affinity binding sites for GnRH analogs coupled to enhanced phosphoinositide turnover and phospholipase D activity. Incubation of alpha T3-1 cells with [D-Trp6]-GnRH analog (GnRH-A) resulted in a rapid increase in gonadotropin alpha-subunit mRNA levels which was detected already at 30 min of incubation (0.1 nM GnRH-A, 3-fold, p < 0.01). The effect diminished with time to reach basal levels at about 12 h of incubation, with a secondary rise in alpha mRNA levels between 12 and 24 h of incubation. Addition of the protein kinase C activator 12-O-tetradecanoylphorbol 13-acetate (TPA, 100 ng/mL) or the Ca2+ ionophore ionomycin (1 microM) to alpha T3-1 cells also resulted in a rapid increase in alpha-subunit mRNA levels. Surprisingly, GnRH-induced alpha-subunit release was detected only after a lag of 4 h of incubation. Thus, dissociation between exocytosis and gene expression can be demonstrated in GnRH-stimulated alpha T3-1 cell line.

Animals↗
PubMed1992

Morphometric studies of pancreatic acinar granule formation in NCTR-Balb/c mice.

NCTR-Balb/c mice are afflicted with a cholesterol lysosomal storage disorder stemming from a defect in intracellular cholesterol processing. The clinical and biochemical abnormalities expressed in the mice resemble Niemann-Pick type C and D disorders in humans. One of the proposed mechanisms to explain the pathophysiology of the disorder implies a defect in the process of membrane transport that normally takes place in the vesicular movement of cholesterol to specific target sites in the cell. Secretory granule formation in pancreatic acinar cells is one of the biological processes known to involve massive membrane flow. Thus, we have undertaken a morphometric study of the regranulation mechanism in the pancreatic acinar cells of the mutant mice, as a way of studying cellular membrane movement. Electron micrographs of pancreatic acinar cells from mutant and normal mice were taken at several time points after extensive degranulation induced by pilocarpine injection. Two hours after stimulation the pancreatic cells demonstrated a complete loss of granules, and at later time points newly formed granules appeared. Identical unit granule volumes were observed in both groups, indicating that the progranules were of normal size. However, the rate of granule formation and maturation was reduced in the mutant mice, which might be the result of a defect in membrane function.

Animals↗
PubMed1992

Unusual renal deposit in mixed connective tissue disease.

We describe a patient with clinical signs of mixed connective tissue disease who developed nephrotic syndrome. The kidney biopsy revealed glomerular and vascular deposits that stained positive with Congo red and showed a green birefringence. The Congo red positivity became negative in sections treated with potassium permanganate. Peroxidase-antiperoxidase staining with anti-AA antibodies was strongly positive. Ultrastructurally, although the deposits were similar to amyloid, they were about twice the size of amyloid fibrils. To our knowledge, the deposition of an amyloidlike material that shows the histochemical and immunohistochemical features of amyloid AA but is lacking the distinctive ultrastructural characteristics of amyloid fibrils has not been described.

Amyloid↗
PubMed1991

Mast cells in rat dermis and jejunal lamina propria show a five-fold difference in unit granule volume.

The cytoplasmic granules of mast cells have a periodic multimodal size distribution in which the volumes of individual granules are integral multiples of the intermodal distance, a volume defined as the "unit granule" or v1. In this study, we used two 3-month-old male rats to analyze two classical mast cell subpopulations, dermal "connective tissue-type mast cells" and jejunal lamina propria "mucosal mast cells", for the morphometric characteristics of their cytoplasmic granules. Both v1 and the mean volume of individual cytoplasmic granules were much smaller in dermal than in jejunal mast cells (ratios of 1:5.5 and 1:4.2, respectively), but dermal mast cells contained 150% more granules per cell than did jejunal mast cells. The two types of mast cells did not differ significantly in total cell volume, nucleus volume, aggregate volume of cytoplasmic granules per cell or numbers of unit granules comprising a granule of mean volume. These findings add unit granule volume to the list of phenotypic characteristics which express significant variation in anatomically distinct populations of mast cells.

Animals↗
PubMed1991

Morphological evidence for chronic mast cell activation after prolonged exposure with supernatants from chronic graft-versus-host splenocytes.

Chronic graft-vs.-host disease (cGVHD) includes a syndrome of inflammatory and fibrotic changes in some respects resembling scleroderma. In the present study we have quantitated the number of peritoneal mast cells (MC) in mice with cGVHD induced across minor histocompatibility barriers. MC were evaluated by staining with toluidine blue. The number of MC decreased significantly (by 25%) at the onset of the cGVHD fibrosis (day 12). Around day 35, MC were virtually undetectable, and started to reappear on day 130. Upon clinical recovery (day 200) a dramatic increase in MC numbers was found (about 8-fold). In addition, we evaluated by electron microscopy the morphology of peritoneal MC, obtained from normal mice and rats, that had been co-cultured on 3T3 fibroblast monolayer in the presence of splenocyte supernatants from mice with cGVHD or from control mice. After 6-8 days of continuous incubation with the cGVHD splenocyte supernatant, MC appeared to be activated, since they displayed an array of heterogenous granules. Few of the granules were dense; many were swollen and pale. Rare granule extrusion was evident. This would indicate that MC underwent a slow activation process due to a factor(s) present in the cGVHD supernatant, different from the classical acute anaphylactic activation.

Animals↗
PubMed1991

Lipid pigment (lipofuscin) accumulation in rat tongue muscle with aging.

Lipid pigment (lipofuscin) was examined in perioral and tongue muscles of aging rats. While in perioral striated muscle the pigmented granules could not be found, a considerable accumulation with aging could be noted in the tongue muscle. Unlike the human tongue muscle, in which the pigmented granules were stored in clusters of different sizes at the nuclear poles of the muscle fibers, in rats, they were scattered randomly through the cytoplasm. The results of this study suggest that lipofuscin can be used as a marker for aging of the tongue muscle in the rat.

Aging↗
PubMed1991

Osteopenia, hematopoiesis, and bone remodelling in iliac crest and femoral biopsies: a prospective study of 102 cases of femoral neck fractures.

Cancellous microanatomy, bone remodelling, and hematopoietic tissue were studied in iliac crest and femoral neck biopsies taken intraoperatively in 102 consecutive patients with displaced intracapsular fractures. About half of the femoral biopsies had osteopenia, and most showed replacement of hematopoietic tissue by fat cells, with absence of osteoblasts and osteoclasts. In contrast, most of the iliac crest biopsies showed relatively less decrease in cancellous bone, while hematopoietic tissue and bone remodelling cells were present in approximately 75%. These results indicate that the iliac crest biopsy does not necessarily reflect cancellous microanatomy, hematopoietic tissue, and bone remodelling at other skeletal sites in any given patient.

Aged↗
PubMed1991

Histopathology of benign prostatic hyperplasia after failure of hyperthermia treatment.

We have used a fine morphometric method to evaluate hyperplastic prostate tissue after treatment by local hyperthermia and compare it with untreated specimens. Local hyperthermia was delivered to the prostate gland by a transrectal applicator using microwaves at 915 MHz. Prostatic tissue was obtained from 13 patients who had completed a course of local hyperthermia treatment and who underwent prostatectomy 3 to 12 months later because the treatment had failed. Prostatic tissue from 9 patients who had undergone prostatectomy with no previous treatment served as a control. A significant reduction in the volume fraction of fibrous tissue was found in the study group (37%) compared with the general population (48%). No inter-group difference was observed in the volume fractions of vascular or glandular tissue. We suggest that the difference observed in the fibrous elements may be the reason for the failure of treatment and that the histological composition of the diseased gland may, therefore, be a key factor in determining the outcome.

Aged↗