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Biomedical subjects

E Bell

Publications and source records attributed to E Bell.

At least 109 records · Page 6Linked to original sources
PubMed1983

Endogenous peroxidases in normal human dermis: a marker of fibroblast differentiation.

Incubation of unfixed and unfrozen slices of normal human skin allows visualization of a peroxidase activity associated with the perinuclear envelope and with the endoplasmic reticulum of resident dermal macrophages, dermal mastocytes, and also of some dermal fibroblasts. No peroxidase activity can be detected in fibroblasts cultivated in monolayer, while 80% of fibroblasts in an "in vitro" collagen lattice, called a dermal equivalent, express a peroxidase activity in the perinuclear envelope and the endoplasmic reticulum. Hence expression of this peroxidase activity in normal human skin fibroblasts serves as a marker of fibroblast differentiation and seems to depend on an interaction to fibroblast with the elements of a three-dimensional matrix.

Adult↗
PubMed1983

The reconstitution of living skin.

A living-skin equivalent useful as a skin replacement and as a model system for basic studies has been fabricated and tested extensively. It consists of two components: (1) a dermal equivalent made up of fibroblasts in a collagen matrix that is contracted and modified by the resident cells, and (2) an epidermis that develops from keratinocytes "plated" on the dermal equivalent. A multilayered keratinizing epidermis with desmosomes, tonofilaments, and hemidesmosomes forms. Basement lamella formation occurs within 2 weeks in vitro when rat cells are used. With human cells, crypt or pseudofollicular morphogenesis is observed in vitro within 3 weeks after plating cells on the dermal equivalent. Autografts and isografts of rat-skin equivalents made with cultured cells from biopsies are rapidly vascularized, block wound contraction, and persist essentially for the lifespan of the host. Seven to 9 days after grafting, donor cells become activated biosynthetically and mitotically. By 1 year, the dermal population decreases to a normal level and the matrix has been extensively remodeled. The grafts remain free of hair and sebaceous glands. Grafts to rats have been in place for over 2 years. Now, allografts of dermal equivalents have been made across a major histocompatibility barrier and are not rejected. The persistence of cellular elements of the grafts is monitored by use of a genetic marker. Challenge of the allograft with a second skin-equivalent graft after 1 month does not result in rejection of the original graft or of the second skin-equivalent graft. We propose that allografts of tissue equivalents are tolerated because cells with class II antigens are selected against during in vitro cultivation and are excluded from the graft. Thus the fabrication of skin-equivalent tissues or of other equivalent tissues with parenchymal cells that do not bear class II antigens may render transplants of such tissues immunologically acceptable despite the presence of allogeneic cells. The capacity to graft across major histocompatibility barriers using living tissue equivalents may have important clinical significance.

Animals↗
PubMed1982

Cytostructural dynamics of spreading and translocating cells.

Cytostructural changes during fibroblast spreading and translocation and during the transition between the two states have been studied in living cells and in the same cells after fixation and immunofluorescent staining. In time-lapse sequences we observe that birefringent arcs, sometimes circles, concentric with the cell perimeter, form near the periphery of a spreading cell, or that arcs form near the leading edge of a locomoting cell. The arcs move toward the nucleus, where they disappear. In spreading cells, radial stress fibers extend from the region of the cell nucleus to the periphery. The arcs or circles and the stress fibers are visualized in the same cells after fixation and staining with fluorescein-conjugated antiactin antibodies. Stained images of spreading cells show the arcs and stress fibers in the same plane of focus. At points of intersection with arcs, stress fibers are bent toward the substrate on which the cell is moving. During a transitional stage between spreading and translocation the cytostructure undergoes reproducible changes. Arcs and circle cease to form. The radial stress fibers elongate, spiral around the nucleus, and move to the periphery as a band of filaments. We interpret the moving arcs as condensations of a microfilament network that move toward the nucleus as compression waves. As elements of the net are brought close together by the compression wave, contraction may occur and facilitate the condensations.

Actins↗
PubMed1982

The relationship of fibroblast translocations to cell morphology and stress fibre density.

Translocation of human fibroblasts in culture was studied using techniques of time-lapse cinemicrography, indirect immunofluorescence, and computer analysis. An inverse relationship between the velocity of cells during the last hour of life and the density of stress fibers seen by immune staining was demonstrated. Translocating cells generally assumed one of two interconvertible morphologies: a triangular tailed shape or tailed fibroblast (TF), and a tailless form that resembled a half-moon, which we call a half-moon fibroblast (HMF). The tail of TFs formed only on regions of substrate that had been previously traversed by cells. The half-moon morphology developed either on previously used or on virgin substrate. Cells adopted the HMF rather than the TF morphology with a four-fold greater frequency. HMFs translocated slightly faster than TFs. The foregoing observation suggest that the fibroblast tail is not an organelle essential for translocation. Since our technique allowed us to distinguish between cells which were cycling and those which had left cycle, we compared their velocities and found them to be similar. Also the average velocities of cells of different population-doubling levels (10th, 30th, 40th) were approximately equal.

Cell Division↗
PubMed1982

Hemolytic and antigenic measurements of complement. A comparison of serum and plasma samples in normal individuals and patients.

Over a 2-year period we evaluated 10 patients with a discrepancy between functional and antigenic assays in the routinely employed clinical assays for measuring serum complement concentrations. These differences were shown to be secondary to cold-dependent activation of the classical complement pathway in vitro, in some cases by cryoglobulins and in others by unknown means. Plasma samples were procured with commonly used anticoagulants (EDTA, citrate, or heparin) that prevent in vitro complement activation. To assess whether plasma samples were suitable for complement determination, a comparison of serum vs. plasma samples for THC, C4, C2, C3, factor B, and C6 levels in normals and patient populations was undertaken. Only modest differences were found between serum and plasma samples for these functional and antigenic assays except for heparinized samples in which determinations by rate nephelometry produced falsely elevated C4, C3, and factor B antigenic levels. Thus plasma samples, especially EDTA or citrate, are suitable for complement determinations and could be used either routinely or, more selectively, in patients in whom there is a discrepancy between functional and antigenic determinations.

Adult↗
PubMed1981

Regulation of proliferation of fibroblasts of low and high population doubling levels grown in collagen lattices.

While IMR 90 and AG 1519 fibroblasts of low and high population doubling levels grow to confluency when plated on plastic surfaces, they cease to divide within four days when incorporated into collagen lattices. Growth inhibition in the lattices is not due to exhaustion of the medium or isotope, or to contact inhibition; nor is it due to impermeability of the lattice to the materials in the medium. While cells in a lattice arrest in G0, this state is reversible when cells are permitted to leave the lattice and populate a plastic substrate. We conclude that fibroblasts in tissue-like lattices may be responsive to some of the same controls as cells in connective tissues.

Animals↗
PubMed1981

Development and use of a living skin equivalent.

We have developed a living skin equivalent, which serves as a skin substitute in experimental animals. On application it is rapidly vascularized, it inhibits wound contraction, and it is immunologically tolerated and persists for as long as it is allowed to remain in place. It comes to resemble normal skin, although it lacks secondary derivatives, the cells for which may in time be available for incorporation into the fabricated tissue.

Animals↗
PubMed1980

[The scintigraphic features of cirrhosis of the liver (author's transl)].

A retrospective study of 101 patients with histologically confirmed cirrhosis of the liver and portal hypertension was carried out in order to evaluate the accepted scintigraphic criteria. In only 20% were all the essential criteria present. The absence of generally accepted important scintigraphic signs does not exclude the diagnosis of cirrhosis of the liver. Specificity of liver scintigraphy in cirrhosis of the liver is fairly low, but sensitivity of the method is almost 100%.

Colloids↗
PubMed1980

The hemicellulose component of dietary fiber.

The digestion of hemicellulose in humans was investigated with subjects with an ileostomy and subjects with healthy small and large bowel on a fixed diet of known fiber content. It was shown that an average of 65% of the hemicelluloses were digested by women ileostomy subjects and 83% by men ileostomy subjects and 97% in the intact women subjects and 95% in the intact men subjects. The monosaccharide composition of the hemicelluloses in the diet, small bowel excreta and feces, suggest that an arabinoxylan hemicellulose from cereals, is not digested in the small bowel and only partly digested in the large bowel. This study suggests that it is the arabinoxylans from cereals that are important components of dietary fiber.

Cellulose↗
PubMed1979

Production of a tissue-like structure by contraction of collagen lattices by human fibroblasts of different proliferative potential in vitro.

Fibroblasts can condense a hydrated collagen lattice to a tissue-like structure 1/28th the area of the starting gel in 24 hr. The rate of the process can be regulated by varying the protein content of the lattice, the cell number, or the concentration of an inhibitor such as Colcemid. Fibroblasts of high population doubling level propagated in vitro, which have left the cell cycle, can carry out the contraction at least as efficiently as cycling cells. The potential uses of the system as an immunologically tolerated "tissue" for wound healing and as a model for studying fibroblast function are discussed.

Animals↗
PubMed1979

An interactive computer system for the analysis of cell lineages.

We have developed an interactive computer system for analysing cell lineage data. It can be utilized in studies of cell motility, cell division, cell differentiation, and cell aging. It has enabled us to document the heterogeneity of human foreskin fibroblasts in culture and to propose that loss of proliferative potential may mean that cells enter a state of differentiation which makes them unable to respond to mitotic stimulation. Our method, which enables us to apply immunological and cytochemical probes after recording the history of a cell lineage, should allow us to define precisely features which uniquely distinguish cycling from noncycling cells on an individual cell basis.

Cell Cycle↗