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Biomedical subjects

E de Harven

Publications and source records attributed to E de Harven.

At least 55 records · Page 3Linked to original sources
PubMed1975

A quantitative comparison between in vivo-and in vitro-derived Friend leukemia virus.

The biological activities of RNA viruses derived from Friend leukemia cells in culture (TCV) were compared with those of viruses derived from the plasma (PV) of mice infected with Friend leukemia virus (FLV). The comparison was quantitatively based on the actual number of viruses used in each experiment as determined by counting under the electron microscope. Electron microscopy also provided a qualitative assessment of the structural integrity of the concentrated virus particles used in various bioassays. The data shows that the leukemogenic and spleen-focus-forming (SFF) activities of TCV, although demonstrable, are respectively 10(5) and 10(4) lower than those of PV. Moreover, TCV has 10(4) less helper activity (S+L- test) than PV. The level of reverse transcriptase activity is ten times lower in TCV than in PV which indicates that there is little correlation between polymerase activity and the other biological activities measured. The decreased biological activity of the in vitro grown virus is thought to be intrinsic to this type of virus although all extrinsic factors have not been ruled out.

Animals↗
PubMed1975

Surface morphology of murine B and T lymphocytes: A comparative study by scanning electron microscopy.

A variety of murine lymphocytes of known B or T derivation obtained from different lymphoid organs were prepared for scanning electron microscopy (SEM) by the critical point drying method after collecting the cells by aspiration onto silver membranes. Comparison of SEM appearances of cells prepared by this technique and serological classification according to surface antigens showed that most T cells had smooth surfaces with few microvilli, while many B lymphocytes were moderately to markedly villous. Further evidence for the above correlation was obtained by examining thymic cells and enriched B or T cell populations. Thymic cell suspensions containing less than 5% B cells showed over 80% generally smooth cells by SEM. Enriched T cell populations, obtained by mass cytolysis of lymph node preparations with anti-Ia or anti-Ig sera or by purification through nylon fiber columns, contained over 85% T cells, and more than 75% of them were of the smooth cell type. A similar correlation was noted for enriched B cell populations obtained by cytolysis of lymph node cells with anti-Thy-1 serum, and by lysis of EAC-rosettes. Over 90% of these cells were identified as B cells by immunologic methods and approximately 75% had moderate to markedly villous surfaces. The 15% difference can be accounted for by the existence of a subpopulation of smooth B cells. Direct observation of EAC-rosettes confirmed that most B cells had moderate to large numbers of surface microvilli and that less than 10% were smooth. It is possible that some of the smooth cells seen in enriched B cell populations may represent precursors or B lymphocytes at different stages of differentiation. These results indicate that murine T and B lymphocytes, like their human counterparts, can be recognized in many cases under the SEM on the basis of their surface morphology. Smoother B and more villous T cells are difficult to classify by SEM without parallel immunologic identification.

Animals↗
PubMed1975

A scanning electron microscopic study of 34 cases of acute granulocytic, myelomonocytic, monoblastic and histiocytic leukemia.

This report describes the surface architecture of leukemic cells, as seen by scanning electron microscopy in 34 patients with acute nonlymphoblastic leukemia. Six patients with myeloblastic, 4 with promyelocytic, 10 with myelomonocytic, 8 with monocytic, 4 with histiocytic and 2 with undifferentiated leukemia were studied. Under the scanning electron microscope most leukemia histiocytes and monocytes appeared similar and were characterized by the presence of large, well developed broad-based ruffled membranes or prominent raised ridge-like profiles, resembling ithis respect normal monocytes. Most cells from patients with acute promyelocytic or myeloblastic leukemia exhibited narrower ridge-like profiles whereas some showed ruffles or microvilli. Patients with myelomonocytic leukemia showed mixed populations of cells with ridge-like profiles and ruffled membranes whereas cells from two patients with undifferentiated leukemia had smooth surfaces, similar to those encountered in cells from patients with acute lymphoblastic leukemia. It appears that nonlymphoblastic and lymphoblastic leukemia cells (particularly histiocytes and monocytes) can frequently be distinquished on the basis of their surface architecture. The surface features of leukemic histiocytes and monocytes are similar, suggesting that they may belong to the same cell series. The monocytes seem to have characteristic surface features recognizable with the scanning electron microscope and differ from most cells from patients with acute granulocytic leukemia. Although overlap of surface features and misidentification can occur, scanning electron microscopy is a useful adjunct to other modes of microscopy in the study and diagnosis of acute leukemia.

Acute Disease↗
PubMed1975

Increased virus budding from Friend erythroleukemic cells treated with dimethyl sulfoxide, dimethyl formamide, and/or bromodeoxyuridine in vitro.

Chronically infected Friend leukemia cells (FLC), grown in the presence of dimethyl sulfoxide (DMSO) (2%, v/v), dimethyl formamide (DMF) (1% v/v), or bromodeoxyuridine (BrdU) (3 or 20 mug/ml) for 4 or 7 days, were examined under the electron microscope. It was found that at the 4th day all three compounds induced comparable increases in the number of budding viruses (3 to 5 times that of the control). At the 7th day, the number had remained relatively constant in the BrdU-treated cells in contrast to the cells of the DMSO- or DMF-treated cultures, which showed a further increase of budding viruses. The greatest increase was seen when BrdU was added in combination with either DMSO or DMF, and this was reflected in the apparent increase in the number of extracellular viruses seen in cell pellets. Scanning electron microscopy on whole FLC mounts provided a rapid means of counting budding viruses and a good correlation was obtained between these counts and those made on thin sections by transmission electron microscopy. Attempts to quantitate the number of released viruses in controls and treated cultures after 4 days of growth revealed a 5- to 10-fold increase per cell in the samples treated with a combination of BrdU and either DMSO or DMF. Thymidine failed to prevent the increase of budding viruses induced by BrdU treatment. The number of budding viruses found after treatment with 3 mug/ml BrdU in the presence of 12 mug/ml thymidine was at a level comparable to that found after the individual BrdU treatment Finally, although FLC always contained varying amounts of intracisternal particles, their number, as compared to the paired controls, always decreased after BrdU treatment.

Animals↗
PubMed1974

Herpes simplex virus and human cytomegalovirus replication in WI-38 cells. II. An ultrastructural study of viral penetration.

An electron microscope study was carried out on the early minutes of herpes simplex virus (HSV) and cytomegalovirus (CMV) penetration into WI-38 cells. Both HSV and CMV entered cells either by fusion of the viral envelope with a limiting cell membrane, or via phagocytosis. Both fusion and phagocytosis occurred within 3 min after the initiation of penetration. After fusion, the naked capsids of CMV free in the cytoplasm became coated with a fine, fibrillar material. CMV capsids thus coated retained a well-defined and easily identifiable morphology until the eclipse of visible viral particles between 1 and 1.5 days postinfection. In contrast, naked HSV capsids free in the cytoplasm were never coated. Rather, within minutes after penetration, they assumed a rounded, less regular outline, and were no longer detectable by 90 to 120 min postinfection. The free naked capsids of both viruses appeared to migrate across the cytoplasm toward the nucleus and to become located near nuclear pores. Both HSV and CMV capsids reached the nucleus as early as 5 min after the initiation of penetration. No further interaction with the nucleus could be documented. Particles were also consistently identified in the Golgi region. Phagocytosed particles generally remained within phagosomes, where they appeared to be degraded. However, stages were identified in what is believed to be the escape of enveloped viruses from phagosomes into the cytoplasm via fusion of their envelope with the phagosomal membrane.

Cell Fusion↗
PubMed1971

A study of gluco-corticosteroid-induced pyknosis in the thymus and lymph node of the adrenalectomized rat.

Pyknotic nuclei, observed in the thymus of steroid-treated rats, are dense, homogeneous, intensely basophilic and Feulgen positive. Under the electron microscope, the image is that of a complete segregation of the chromatin from the nuclear sap producing a margin or crescent of condensed chromatin. Approximately 30% of all small thymocytes appeared to undergo this type of degeneration within 3-4 hr after administration of the synthetic corticosteroid, dexamethasone. At this time, pyknotic thymocytes were observed in clusters, probably as a result of the activity of dense reticular cells and macrophages. Topographical and experimental data suggest the existence of a select population of steroid-sensitive thymic cells. Furthermore, on the basis of thymidine-(3)H incorporation studies, it appears that the steroid-sensitive population of thymocytes does not correspond to "aged" cells. In addition, many plasma cells became pyknotic after the same steroid treatment, indicating an unexpected similarity between their nuclei and those of lymphocytes. Finally, steroid failed to induce pyknosis of thymocytes in a variety of in vitro experiments, suggesting that the in vivo effect of steroid is of an indirect nature. The results are discussed in terms of (a) the nature of the nuclear changes characterizing pyknosis, (b) the hypothetical mechanism whereby steroids trigger such changes, and (c) the population of cells susceptible to steroid-induced pyknosis.

Adrenalectomy↗
PubMed1968

Use of hybrid antibody with anti-gamma-G and anti-ferritin specificities in locating cell surface antigens by electron microscopy.

Hybrid antibody [F(ab')(2)] with dual specificity for mouse gammaG and ferritin was prepared from the corresponding rabbit antisera, providing a precise reagent for locating mouse gammaG on cell surfaces. Viable cells were exposed successively to (a) mouse antibody to a cell surface antigen, (b) the rabbit hybrid antibody, and (c) ferritin, before preparation for electron microscopy. This method of See PDF for Structure. labeling is sensitive and specific and clearly lends itself to the introduction of visual markers other than ferritin. Other advantages are uniformity of labeling, ease of purification of the reagent, and circumvention of the many drawbacks arising from coupling ferritin to antibody chemically.

Animals↗