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Biomedical subjects

H M Dembitzer

Publications and source records attributed to H M Dembitzer.

At least 19 recordsLinked to original sources

Neuropathology of acquired immune deficiency syndrome (AIDS) in 53 autopsy cases with particular emphasis on microglial nodules and multinucleated giant cells.

Brains from 53 autopsied acquired immune deficiency syndrome (AIDS) cases were examined with special attention to microglial nodules and multinucleated giant cells, which are two histological features of AIDS encephalopathy. Twenty-four (45%) of the 53 brains had microglial nodules in varying frequency. Four of these had microglial nodules alone and the rest had other pathological changes, such as opportunistic infections, CNS lymphomas, cerebrovascular lesions, and multinucleated giant cells. Eleven (46%) of the 24 brains with microglial nodules were accompanied by cytomegalovirus infection in the brain (one case) or body (five cases), or both (five cases). However, the remaining 54% of the brains had no morphological evidence of cytomegalovirus infection either in the brain or body. Five brains had multinucleated giant cells and microglial nodules. Two of these brains had numerous multinucleated giant cells, especially in the cerebral white matter, where, in one case, a spectrum of forms included mononuclear macrophages, intermediate forms of binuclear and trinuclear cells, and multinucleated giant cells. Images suggesting cell fusion were also observed. Electron microscopic examination of this area revealed many viral particles (80-130 nm in diameter) with rod-like cores, reminiscent of HTLV-III, in the cytoplasm of one cell.

Acquired Immunodeficiency Syndrome↗

The periaxonal space in an experimental model of neuropathy: the mutant Syrian hamster with hindleg paralysis.

The periaxonal space of peripheral myelinated axons was studied in the mutant Syrian hamster with hindleg paralysis, an experimental model of neuropathy. Despite pronounced alterations of the axon and the surrounding sheath, sometimes leading to demyelination, the periaxonal space showed remarkable resistance to change in most instances. When the space was widened as the result of the infiltration of extracellular fluid, the axon was found at the periphery of the enlarged inner perimeter of the sheath. Even under these extreme conditions the axon maintained close to normal distance from the inner collar of cytoplasm. The significance of these findings with regard to both the normal anatomical relationship within the sheath and to the mechanisms of demyelination are discussed.

Animals↗

Desmosome development in an in vitro model.

A model has been devised to study the in vitro formation of desmonsomes. The model is based on the differential labeling of two subpopulations of a desmosome-forming human cancer line (C4I). The labeled subpopulations are dispersed, preincubated separately on a shaking water bath for 24 h to allow the internalization of desmosome fragments and the repair of the cell surface, and then mixed, and allowed to aggregate. Aliquots of the mixed suspension are fixed at various intervals. The time between mixing and fixation represents the maximum age of any junction between dissimilarly labeled cells. The beginnings of desmosome formation were observed within a few minutes after the beginning of aggregation. Close apposition of cell membranes was seen immediately after mixing, followed within 15 min by the appearance of a submembrane density in one or both of the interacting cells. Intracytoplasmic filament formation takes place at between 15 and 30 min. Desmosome formation is complete by 90 min. The process is accompanied by a progressive widening of the extracellular space and the desification and organization of the extracellular material and the submembrane plaques.

Cell Adhesion↗

Unusual intracytoplasmic inclusions in a case of idiopathic scleritis.

Large cells containing prominent, refractile PAS-positive inclusions were found in cytological smears prepared from scrapings of the conjunctiva of an elderly diabetic patient with idiopathic scleritis progressing to scleromalacia perforans. Electron-microscopic study of these inclusions revealed them to be intracellular accumulations of dense, flocculent mucoid material within vacuoles whose interior surface was frequently decorated with microvilli. Similar inclusions have been reported in a number of neoplasms in nonocular tissue. The significance of these findings with regard to the patient's condition is not understood.

Aged↗

Development of Purkinje cell somatic spines in the weaver mouse.

The cerebellar cortices of weaver mice and their normal littermates ranging in age from six to thirteen days after birth were examined with the electron microscope. The initial development of spines, both somatic and dendritic, are the same in both the weaver and its normal littermates despite the extreme paucity of parallel fibers in the former.

Animals↗

The fine structure of astrocytes in the adult staggerer.

The fine structure of the cerebella of staggerer mice was studied. Particular attention was paid to the astrocytic processes which showed characteristic changes in the adult animal. These consisted of parallel configurations of slender sheet-like astrocytic processes frequently connected to one another by highly organized intercellular adhesive devices. The abnormal condition seen in staggerer is an exaggerated expression of the fundamental tendency of the astrocyte to form sheet-like peripheral processes.

Animals↗

Electron microscopic immunohistochemical identification of endothelial cells in the rabbit.

Antibody to tissue factor apoprotein was adsorbed against gamma-globulin and coupled to horseradish peroxidase; this complex was applied to various rabbit tissues. The distribution of the peroxidase marker then was observed by electron microscopy. We examined fixed or frozen sections, as well as breis of aorta, vena cava, brain, heart, lung, liver, spleen, kidney, bone marrow, mesothelial gut lining, erythrocytes, and platelets. All endothelial cells that had been exposed to the antibody complex were positive and in all cases only the endothelial cells showed localization of the electron-dense reaction product. Tissues that had been incubated with complexes prepared with gamma-globulin from animals not immunized with tissue factor apoprotein showed no staining. Prior treatment of the tissue with uncoupled anti-tissue factor gamma-globulin blocked binding by the coupled antibody. In blood vessel preparations that had been specifically designed to expose the media to the anti-tissue factor complex, medial smooth muscle cells and connective tissue showed no reaction product. Parenchymal cells of the other other organs mentioned likewise were devoid of reaction product. Similarly, the leukocytes and platelets occasionally observed in vessel lumens showed no evidence of binding. Platelets adhering to arterial subendothelial structure after injury also were unreactive. These findings suggest that in normal rabbits anti-tissue factor-horseradish peroxidase complex combines selectively with endothelial cells.

Adsorption↗

The use of a slide spinner in the analysis of cell dispersion.

A simple and reliable method of determining the degree of dispersion of a cell suspension has been developed using the Perkin-Elmer Uni-Smear Spinner. Optimum conditions regarding rate and duration of spin, etc., were first ascertained using dispersed cell cultures including human cervical cancer cells as well as gynecologic samples. After spinning, single cells in suspension appeared as isolated cells on the slides. Cell aggregates, on the other hand, remained together. Therefore, the distribution of cells in various sized aggregates could be easily quantitated and the slides retained for future review. This method was used to evaluate the dispersing effects of trypsin, ethylenediaminetetraacetate and and syringing human on human gynecology samples obtained by routine cervical scrapes. None of the dispersion methods has, so far, produced an adequate monodispersed cell suspension without unacceptable cell loss.

Autoanalysis↗

The fine structure of staggerer cerebellum.

The cerebellar cortex of staggerer mice, ranging in age from 12 days to three months, was studied in the electron microscope. In general, the cerebellum showed a much delayed developmental pattern with regard to Purkinje cell spine formation. Spines did not appear on the soma until about 6 days after birth and appeared on the dendritic branchlets at only 23 days. Climbing fibers were present and they were in synaptic contact with both somatic and dendritic spines. By the third month, spines were only rarely obserbed and some of these were unattached to any presynaptic element.

Aging↗

Cerebellar alterations in the weaver mouse.

The fine structure of the cerebellum of weaver mouse was examined and the paucity of granule cells and their axons, the parallel fibers, was confirmed. Unexpectedly, however, the dendritic spines of the Purkinje cells which, in normal animals, are the postsynaptic mates of the parallel fibers, were present. Furthermore, their essential morphology and their staining reactions were indistinguishable from those of the Purkinje cell dendritic spines in normal animals. Possible mechanisms of development are discussed.

Acetates↗