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I Hammel

Publications and source records attributed to I Hammel.

68 records · Page 4Linked to original sources
PubMed1985

Differences in the volume distributions of human lung mast cell granules and lipid bodies: evidence that the size of these organelles is regulated by distinct mechanisms.

We analyzed transmission electron micrographs of human lung mast cells by digitized planimetry and point counting to determine the cross-sectional areas of two distinct cytoplasmic organelles: specific granules and lipid bodies. Specific granules have a limiting membrane and often contain one or more cylindrical scroll-like inclusions. By contrast, lipid bodies are on average much larger than granules and lack both limiting membranes and inclusions. The measured cross-sectional areas of lipid bodies and scroll-containing granules were converted to equivalent volumes, and the noise in the frequency distribution of these volumes was smoothed using a moving bin technique. This analysis revealed (a) a periodic, multimodal distribution of granule equivalent volumes in which the modes fell at volumes that were integral multiples of the volume defined by the first mode (the "unit volume"), and (b) a modal granule equivalent volume frequency that occurred at a magnitude equal to four "unit volumes." Thus, specific granules appear to be composed of units of a narrowly fixed volume. Furthermore, the mean volume of intragranule inclusions was 0.0061 mu3, a value very similar to that calculated for the "unit volume" (0.0071 mu3). This result suggests that each "unit volume" comprising the individual scroll-type granules contains (or is capable of generating or accommodating) a single scroll-like inclusion. In contrast to the specific granules, mast cell lipid bodies lack a periodic, multimodal volume distribution. Taken together, these findings suggest that the volumes of human lung mast cell granules and lipid bodies are regulated by distinct mechanisms.

Cytoplasmic Granules↗
PubMed1985

Cloned mouse mast cells and normal mouse peritoneal mast cells. Determination of serotonin content and ability to synthesize serotonin in vitro.

We determined the serotonin (5-hydroxytryptamine, 5HT) content of growth factor dependent mouse mast cell lines or clones, and measured their ability to synthesize and store 3H-5HT from exogenous 5-hydroxy-[G-3H]-tryptophan (3H-5HTP) in vitro. Mast cells grown in vitro synthesized 3H-5HT from 3H-5HTP at rates equal to or greater than those of peritoneal mast cells freshly isolated from normal mice. Furthermore, under usual conditions of culture, mast cell lines or clones contained more 5HT than freshly isolated peritoneal mast cells.

5-Hydroxytryptophan↗
PubMed1984

Unequivocal delayed hypersensitivity in mast cell-deficient and beige mice.

It has been suggested that reserpine blocks expression of delayed hypersensitivity in mice because it depletes stores of the vasoactive amine serotonin in mast cells. To determine whether mast cell serotonin or other mast cell-derived mediators are essential for delayed hypersensitivity, responses to contact sensitizers in mast cell-deficient W/Wv or Sl/Sld mice were studied. Because blood platelets represent another potential source of serotonin in delayed hypersensitivity responses, beige mice, whose platelets contain less than 1 percent of the normal levels of serotonin, were also examined. By the criteria of tissue swelling, infiltration of iodinated leukocytes, or histology, mast cell-deficient or beige mice expressed delayed hypersensitivity reactions whose intensity generally equaled or exceeded that of reactions in littermate controls. In addition, reserpine blocked delayed hypersensitivity in W/Wv and beige mice, suggesting that effects on mast cell or platelet serotonin cannot explain this drug's action in delayed hypersensitivity.

Animals↗
PubMed1984

Differences in the behavior of cytoplasmic granules and lipid bodies during human lung mast cell degranulation.

We used a morphometric and autoradiographic approach to analyze changes in specific cytoplasmic granules and cytoplasmic lipid bodies associated with human lung mast cell degranulation. Mast cells were dissociated from lung tissue by enzymatic digestion and were then enriched to purities of up to 99% by countercurrent centrifugation elutriation and recovery from columns containing specific antigen bound to Sepharose 6 MB. Degranulation was induced by goat anti-IgE. At various intervals after stimulation, parallel aliquots of cells were recovered for determination of histamine release or were fixed for transmission electron microscopy. We found that lipid bodies, electron-dense structures that lack unit membranes, were present in both control and stimulated mast cells. Autoradiographic analysis showed that lipid bodies represented the major repository of 3H-label derived from [3H]arachidonic acid taken up from the external milieu. By contrast, the specific cytoplasmic granules contained no detectable 3H-label. In addition, lipid bodies occurred in intimate association with degranulation channels during mast cell activation, but the total volume of lipid bodies did not change during the 20 min after stimulation with anti-IgE. This result stands in striking contrast to the behavior of specific cytoplasmic granules, the great majority of which (77% according to aggregate volume) exhibited ultrastructural alterations during the first 20 min of mast cell activation. These observations establish that mast cell cytoplasmic granules and cytoplasmic lipid bodies are distinct organelles that differ in ultrastructure, biochemistry, and behavior during mast cell activation.

Antibodies, Anti-Idiotypic↗
PubMed1984

The role of connexon aggregate fusion in gap junction growth.

Gap junctions are thought to grow in size by the incorporation of single connexons and by the fusion of connexon aggregates but the relative importance of these two growth mechanisms, particularly in the formation of large gap junctions, remains unclear. We have used a quantitative approach to distinguish between these two growth mechanisms and present evidence here that gap junctions in Drosophila melanogaster wing discs have a periodic, (approximately equal to 0.025 micron 2), multimodal areal distribution which suggests that gap junctions grow by aggregate fusion. Previously published gap junction areal frequency distributions from another invertebrate, Manduca sexta, and from several vertebrate animals also show periodic (approximately equal to 0.030 micron 2), multimodal areal distributions. We suggest that the interpeak spacings on the frequency distributions represent average areas of 'unit aggregates' of connexons and that the fusion of such unit aggregates with one another and with integral multiples of unit aggregates may be a general mechanism for gap junction growth. Unit aggregates in mammals and insects are similar in surface area rather than in connexon number suggesting that a common molecular mechanism, perhaps operating at the level of the plasma membrane, may be involved in their formation and stabilization.

Animals↗
PubMed1983

Periodic, multimodal distribution of granule volumes in mast cells.

The areas of 2327 mast cell granules in transmission electron micrographs of sections of peritoneal mast cells from adult rats were measured by digitized planimetry. A histogram constructed using equivalent volumes calculated from the measured areas assuming approximation of the granules to spheres showed a periodic multimodal distribution in which the modes fell at volumes that were successively larger integral multiples of the volume at the first mode. Application of a moving-bin technique to the data confirmed the presence of the modes. We propose a mechanism of fusion of unit sized granules to account for the multimodal distribution. The presence of pear- and dumbbell-shaped granules in mast cells is consistent with this mechanism.

Animals↗
PubMed1981

Mast cells in Behçet's disease: ultrastructural and histamine content studies.

In order to assess the role of mast cells in the pathogenesis of mucocutaneous lesions of Behçet's disease, the following investigations were performed: (1) a comparative study of ultrastructural features of mast cells in spontaneous and reactive (pathergic) lesions of the process and in apparently uninvolved skin of patients in the active stage of the disease; (2) comparative estimation of the histamine content at the site of cutaneous hyperreactivity lesions and in apparently uninvolved skin of the same patients. Various forms and degrees of degranulation were revealed among the mast cells. These forms were obviously more frequent in spontaneous and reactive lesions than in the uninvolved skin, 66 and 56% as compared with 7.7%. Also the histamine content was twofold more in the reactive lesions than in the unaffected skin of the same patient, 43 ng/mg tissue as compared with 21 ng/mg tissue. The results of our study seem suggestive of an active role of mast cells in this process. The role is probably similar to that of basophils in cutaneous basophilic hypersensitivity.

Behcet Syndrome↗
PubMed1980

The quantification and significance of mast cells in lesions of Behçet's disease.

Mast cells in the upper dermis and mucosal subepithelial layer were counted in thirty consecutive light microscopy oil-immersion fields of the following: thirty-four skin and oral specimens from lesions in patients with active Behçet's disease, eight specimens of apparently uninvolved skin of the same patients, and 102 lesions of a variety of other skin diseases. The results revealed a significant increase in the number of mast cells in Behçet's lesions. Furthermore, the histamine content of five reactive lesions showed a two-fold increase compared with that in apparently uninvolved skin of patients with active Behçet's disease. It is suggested that mechanisms similar to cutaneous basophil hypersensitivity may be involved in the production of Behçet's lesions.

Behcet Syndrome↗
PubMed1978

Differentiation and activity of mast cells following immunization in cultures of lymph-node cells.

An extensive clonal differentiation into mast cells from primitive blast cell precursors occurred when lymph node cells obtained from mice immunized with horse serum were cultured on mouse embryonic skin monolayers. Horse serum was always present in the culture as a constituent of the nutritional medium. Mast cells developed to lesser extent also in cultures prepared from non-immunized mice. However, a clear difference in mast cell-granule ultrastructure and in histamine content was noted between the two. In cultures of lymph nodes cells from non-immunized mice the granules were tiny and uniform in size and in staining density; whereas granules in the immune cultures were larger and non-uniform in size and in staining density, and the intragranular organization manifested alterations of various forms. The content of intracellular histamine per 10(6) mast cells was about equal in both cultures. However, much more free histamine (per 10(6) mast cells) gradually accumulated in cultures of the immune lymph node cells, indicating higher rates of synthesis and release of histamine. The mast cells were readily degranulated by heat-inactivated (IgG1) sera of the mice used as donors of the lymph node cells. 92% of the mast cells were degranulated and as much as 80% of the histamine was released. The degranulation was accompanied by an immediate (albeit reversible) response of the fibroblast cells in the monolayer. A shift of the well-stretched cytoplasm of the fibroblasts opened numerous 'window' over the whole monolayer. The degranulated mast cells survived the process and could be maintained further in the cultures. Moreover, they were capable of repeated degranulation, releasing 50% of their histamine, even after four degranulation cycles performed over a 7 days' period of culture. No cytotoxic effect on the mast cells was noted and the histamine content in culture, 3 days after degranulation, seemed to be higher than in the undergranulated control cultures--suggesting an intensified rate of histamine synthesis.

Animals↗
PubMedDate not supplied

Histochemical characterization of collagen fibers in fibrous overgrowth (irritation fibroma) of the oral mucosa: effect of age and duration of lesion.

In a study of 43 specimens of oral mucosa irritation fibroma, polarization colours of collagen thin (0.8 microm) and thick (1.6-2.4 microm) fibers were recorded in formalin-fixed and paraffin-embedded sections stained with Picrosirius red. Examination of polarization colours of both the 'thin' and 'thick' collagen fibers revealed an increase of yellowish-orange and orange fibers as a function of age in patients over 30 years old (P < 0.05 only in thick fibers). When the polarization colours of thin and thick collagen fibers were recorded as a function of duration of the lesion, there was an increase in the number of yellowish-orange and orange fibers and a decrease in blue-green and green fibers in both thin (P < 0.1) and thick (P < 0.05) populations as the lesion matured. These findings show that increments in both the patient's age and the duration of the lesions increase the amount of collagen fibers which exhibit yellowish-orange and orange polarization colours indicating tighter packing and better alignment of the microfibrils, similar to normal mature collagen. These differences may have an effect on the timing of the surgical excision.

Journal Article↗
PubMedDate not supplied

The rigidity of bacterial flagellar filaments and its relation to filament polymorphism.

We determined and correlated the rigidity of Salmonella typhimurium, Escherichia coli, and Rhizobium lupini flagellar filaments representing various structural and polymorphic states (plain, complex, straight, superhelical, and right- and left-handed). Persistence length, from which the filament's rigidity and other parameters (Young's modulus, bending force constant, buckling persistence length, flexural deformation, and flexural time) were derived, was determined from electron micrographs of isolated, negatively stained filaments. Outer diameters and radii of strong intersubunit connectivity were determined from three-dimensional image reconstructions and radial mass density profiles from scanning transmission electron microscopy. All filaments appear to be highly rigid with no evident correlation with their helical sense or superhelicity. The complex filament of R. lupini is rigid to the extent that it becomes brittle. The overall flexibility of the flagellum seems to stem mainly from the hook and not from the filament. Polymorphism is probably related to the propelling properties and hydrodynamic shape of the filament rather than to its rigidity.

Escherichia coli↗
PubMedDate not supplied

A new scoring system using multiple immunohistochemical markers for diagnosis of uterine smooth muscle tumors.

The diagnosis of uterine smooth muscle neoplasms by light microscopy is difficult. Multiple classification schemes have been proposed based on mitotic rate, nuclear atypia, and the presence or absence of necrosis. None of these classification systems has been entirely successful. This study was undertaken to evaluate the use of selected immunohistochemical and histochemical markers in differentiating these tumors, in addition to accepted morphologic criteria. Ten cases of each of the following: leiomyosarcomas (LMS), atypical leiomyomas (AL), cellular leiomyomas (CL) and usual leiomyomas (UL), were classically evaluated for histological diagnosis and were stained for Ki-67 (MIB-1), bcl- 2 and p53 using monoclonal antibodies and the avidin-biotin peroxidase method, and argyrophilic nucleolar organizer region (AgNORs). The number of stained cells was counted in the most positively stained region in a 4 mm2 square cover glass mounted on each slide. The mean value was calculated for each group of tumors. The data for Ki-67 (MIB- 1), bcl-2, p53 and AgNOR staining respectively, were significantly higher in LMS by comparison to UL, CL or AL. Because many singular cases had superimposed data being difficult to diagnose, a new scoring system for pathological evaluation was created. The results obtained by this scoring system suggest that immunohistochemical markers Ki-67 (MIB-1), bcl-2, p53 together with the AgNOR staining could be useful, by the scoring system, as an adjunct to the current accepted morphologic criteria in differentiating smooth muscle tumors of the uterus.

Antigens, Nuclear↗