Dermal eosinophils in atopic dermatitis undergo cytolytic degeneration.

BACKGROUND: Immunofluorescent staining for eosinophil granule proteins in lesional skin of patients with atopic dermatitis shows extensive extracellular deposition throughout the upper dermis with relatively few intact eosinophils. OBJECTIVE: This study was carried out to determine whether eosinophil granule protein deposition in atopic dermatitis occurs by classical exocytosis, by piecemeal degranulation, or as a result of cytolysis. METHODS: Skin biopsy specimens from 10 patients with atopic dermatitis were examined by electron microscopy. RESULTS: The biopsy specimens showed varying degrees of dermal eosinophil granule major basic protein deposition by indirect immunofluorescence. Specimens from seven patients showed striking alterations of eosinophils by electron microscopy including intact eosinophils with granule alterations (reversal of core staining and/or core lucency) and with uropod processes. Biopsy specimens from six patients showed evidence of eosinophil degeneration with disruption of nuclear and/or plasma membranes. In four patients' specimens, membrane-bound eosinophil granules were present near degenerating eosinophils or were present in the absence of recognizable eosinophils. Evidence of classical exocytotic degranulation was not observed. Two of the specimens were also examined by immunoelectron microscopy for major basic protein localization. In these, major basic protein appeared to be lost from the granule core and distributed in the eosinophil cytoplasm as granules disintegrated and the cell disrupted. CONCLUSION: These findings support the hypothesis that eosinophils undergo cytolysis with release of granule contents and membrane-bound granules; this is likely the usual mechanism of eosinophil granule protein release in atopic dermatitis.

Mixed ependymoma-neuroendocrine tumor of the lateral ventricle.

A histologically unique glioneuronal neoplasm occupying the lateral ventricle of a child was immunohistochemically and ultrastructurally characterized. Its principal component exhibited the characteristic features of ependymoma, whereas a minor population of neuroendocrine cells, occurring singly and in small clusters, lay scattered throughout the ependymoma component. Yet another unusual finding was the presence of numerous elastic fibers within the extracellular matrix. This tumor is considered to represent a true mixed neoplasm consisting of ependymal and neuroendocrine elements.

Tuber and subependymal giant cell astrocytoma associated with tuberous sclerosis: an immunohistochemical, ultrastructural, and immunoelectron and microscopic study.

The cellular nature of the giant eosinophilic cells of tuber and of the cells comprising subependymal giant cell astrocytoma (SEGA) in tuberous sclerosis (TS) remains unclear. To assess the characteristics of these lesions, 13 tubers and 6 SEGA were immunohistochemically studied with glial and neuron-associated antigens. In addition to conventional ultrastructure, 6 tubers and 8 SEGA were subjected to immunoelectron microscopic study for glial fibrillary acidic protein (GFAP) and somatostatin. Eosinophilic giant cells of tubers were positive for vimentin (100%), GFAP (77%) and S-100 protein (92%); such cells were also found to a various extent to be reactive for neuron-associated antigens, including neurofilament (NF) proteins (38%) or class III beta-tubulin (77%). SEGA also showed variable immunoreactivity for GFAP (50%) or for S-100 protein (100%); NF epitopes, class III beta-tubulin, and calbindin 28-kD were expressed in 2 (33%), 5 (83%) and 4 (67%) cases, respectively. Cytoplasmic staining for somatostatin (50%), met-enkephalin (50%), 5-hydroxytryptamine (33%), beta-endorphin (33%) and neuropeptide Y (17%) was noted in SEGA, but not in tubers. Ultrastructurally, the giant cells of tubers and the cells of SEGA contained numerous intermediate filaments, frequent lysosomes and occasional rectangular or rhomboid membrane-bound crystalloids exhibiting lamellar periodicity and structural transition to lysosomes. Some SEGA cells showed features suggestive of neuronal differentiation, including stacks of rough endoplasmic reticulum, occasional microtubules and a few dense-core granules. Furthermore, in one case of tuber, a process of a single large cell was seen to be engaged in synapse formation. Intermediate filaments within a few cells of both lesions were decorated by gold particle-labeled GFAP antiserum. Within the tumor cells of SEGA, irregular, non-membrane-bound, electron-lucent areas often contained somatostatin-immunoreactive particles, whereas the latter could not be detected in tuber. The present study provides further evidence of divergent glioneuronal differentiation, both in the giant cells of tubers and the cells of SEGA. The findings of similar cells at different sites, including the subependymal zone, white matter ("heterotopias"), and cortex indirectly supports the idea that these lesions of TS result from a migration abnormality.

The osmotic effect of glycerol on the stria vascularis and endolymph.

In the chinchilla, quantitative changes in strial thickness, area of the endolymphatic space, serum osmolality, and serum levels of glycerol, glucose, total protein sodium, potassium and chloride were determined at 1, 2, 3 and 5 h after the intraperitoneal administration of 6 g/kg glycerol. The serum osmolality, glycerol, glucose and potassium levels increased, while serum sodium and chloride decreased. Quantitative changes in cochlear structure included an increase in strial thickness and a decrease in area of the endolymphatic space. In all the animals (n = 50), the increase in strial thickness was closely correlated (correlation coefficient r = 0.57) to an increase in serum osmolality. This correlation with strial thickness improved (R = 0.71) when the interval between injection and animal sacrifice was used in combination with serum osmolality. The increase in stria thickness was also closely correlated to an increase in serum glycerol and to a decrease in serum chloride. A decrease in endolymphatic volume was found most consistently at 3 h after the i.p. administration of glycerol.

The osmotic effect of glycerol on the stria vascularis and endolymph.

In the chinchilla, quantitative changes in strial thickness, area of the endolymphatic space, serum osmolality, and serum levels of glycerol, glucose, total protein sodium, potassium and chloride were determined at 1, 2, 3 and 5 h after the intraperitoneal administration of 6 g/kg glycerol. The serum osmolality, glycerol, glucose and potassium levels increased, while serum sodium and chloride decreased. Quantitative changes in cochlear structure included an increase in strial thickness and a decrease in area of the endolymphatic space. In all the animals (n=50), the increase in strial thickness was closely correlated (correlation coefficient r=0.57) to an increase in serum osmolality. This correlation with strial thickness improved (R=0.71) when the interval between injection and animal sacrifice was used in combination with serum osmolality. The increase in stria thickness was also closely correlated to an increase in serum glycerol and to a decrease in serum chloride. A decrease in endolymphatic volume was found most consistently at 3 h after the i.p. administration of glycerol.

Cochlear vessel permeability to horseradish peroxidase in the normal and acoustically traumatized chinchilla: a reevaluation.

A method involving incubation of intact cochleae using the small protein, horseradish peroxidase, has revealed that a barrier exists between the blood and the stria vascularis. This barrier is more tenuous than the barrier that exists across other cochlear vessels. The stria-strial vessel barrier can be altered physiologically by acoustic trauma or artifactually by dissection.

Mannitol-induced stria vascularis edema.

After administration of mannitol, an osmotic diuretic, edema of the stria vascularis occurs, which is morphologically indistinguishable from the stria edema observed after administration of loop-inhibiting diuretics. Similar edema also was observed after glycerin administration. Both mannitol and glycerin may act osmotically to draw fluid from the endolymph into the stria. Temporary improvement in the hearing level and discrimination from the glycerin test in endolymphatic hydrops could be explained by this potential mechanism of endolymph volume reduction.

Cochlear fluid balance. A clinical/research overview.

Stria edema, and in some cases atrophy, follows osmotic agents, loop-inhibiting diuretics, acoustic trauma, and rupture of Reissner's membrane. All have in common an imbalance of fluid and electrolytes in the cochlear duct. The glycerol test causes temporary improvement in hearing in Menière's disease. Glycerol causes stria edema and collapse of Reissner's membrane in the chinchilla. Stria edema, as well as stria atrophy, are found in Menière's disease. Metabolic manipulation of the stria might be that the best approach in the search for successful treatment of Menière's disease.

The morphologic effects of histamine on the lateral cochlear wall.

The chinchilla lateral cochlear wall (stria vascularis, spiral ligament, and spiral prominence) was examined by morphologic and histochemical techniques following various doses of intravenous histamine. The three main findings were as follows: (1) the basic ultrastructure was not altered by histamine; (2) there is a time- and dose-dependent change in the rate of stria vascularis vessel permeability to a small protein tracer (horseradish peroxidase), but the mode of transport (large pore system) is unchanged; and (3) glycogen depletion in stria marginal cells occurs with its apparent mobilization into stria intercellular spaces.

Delineation of cochlear glycogen by electron microscopy.

Two techniques for the demonstration and identification of glycogen by electron microscopy were applied to the cochlear duct tissues of normal guinea pigs and chinchillas. A modified osmium tetroxide fixative (with potassium ferricyanide) has been described by De Bruijn to selectively stain the glycogen particle. Identification of the stained particle was effected by its selective removal from the tissue with amyloglucosidase, an enzyme specific in its degradation of the glycogen molecule. Glycogen particles were noted in several cell types within the cochlear duct, but concentrations were greater in outer hair cells of both species and in the stria vascularis of the chinchilla. The fact that amyloglucosidase completely eliminated these particles from the liver of both species as well as cochlear tissue, led to the conclusion that these particles are indeed glycogen.