Biomedical subjects

E P de Harven

Publications and source records attributed to E P de Harven.

3 recordsLinked to original sources

PubMed1995

Cell surface changes of hemopoietic cells during normal and leukemic differentiation: an immuno-scanning electron microscopy study.

Hemopoietic cells display a wide range of cell surface antigens which are either lineage specific or acquired during differentiation. Monoclonal antibodies can be used, in conjunction with colloidal gold markers, to identify under the scanning electron microscopy (SEM) at the single cell level, specific lineage or maturation stages in the hemopoietic bone marrow. Normal bone marrow cells, either gradient separated or purified by immuno-magnetic methods and leukemic cell samples, which can be considered as "frozen" stages of hemopoietic differentiation, have been studied with this method. Typical cell surface morphologies, which characterize immature progenitor cells and cells committed or differentiated towards the lymphoid, myeloid, erythroid and megakaryocytic lineage have been identified. Correlations between cell surface features and some hemopoietic cells functions have been attempted on the basis of these findings.

Antibodies, Monoclonal↗

PubMed1993

Human chromosomes: evaluation of processing techniques for scanning electron microscopy.

Methods for scanning electron microscopy (SEM) of chromosomes have been developed in the last two decades. Technical limitations in the study of human chromosomes, however, have hindered the routine use of SEM in clinical and experimental human cytogenetics. We compared different methodologies, including metal impregnation, air drying and specimen coating. SEM preparation of human chromosomes in which osmium impregnation is mediated by tannic acid, yielded more reproducible results when compared with osmium impregnation protocols previously described. The level of osmium impregnation was systematically evaluated by imaging chromosomes in the backscattering mode. Critical point drying and a light gold-palladium coating were essential for appropriate secondary electron imaging of chromosomes. With this method, and in a preliminary quantitative analysis, we show that our SEM technique is more sensitive than light microscopy for the detection of aphidicolin-induced fragile sites. This technical approach is useful for chromosomal studies requiring resolution higher than that obtained by light microscopy. Also, it allows the use of clinical and archival chromosomal samples prepared by routine cytogenetic techniques.

Adult↗

PubMed1987

Lipid degeneration in pheochromocytomas mimicking adrenal cortical tumors.

A case of bilateral adrenal pheochromocytomas with unusual morphologic features is reported in a 27-year-old man with a family history of von Hippel-Lindau disease. In both glands, the medulla was replaced by neoplasms with two distinct gross and microscopic appearances. There was typical pheochromocytoma in areas of dusky red tissue. The yellow nodules noted on gross examination were microscopically composed of large cells with vacuolated cytoplasm. Fat stains confirmed the presence of lipid in these areas. Immunohistochemistry revealed positivity for neuron-specific enolase and chromogranin in the cytoplasm of pheochromocytes, as well as in the perinuclear cytoplasm and processes of cells scattered in the yellow nodules. Ultrastructural examination of the yellow lesions showed characteristics of pheochromocytoma and an extensive accumulation of lipid. Although gross and light-microscopic examination of the yellow tissue suggested adrenal cortical nodules, immunohistochemistry and electon microscopy elucidated lipid degeneration within pheochromocytoma, a finding not previously described.

Adrenal Cortex Neoplasms↗