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PubMed1989

Adenine uptake by rat connective tissue cells with special reference to macrophage precursors.

After 3 daily injections of [14C]adenine ([14C]A) (1 microCi/g body weight each) into young adult rats, the large majority of typical, spindle-shaped fibroblasts in the connective tissues of most organs showed almost no labeling, with the exception of a few weakly labeled ones. In contrast, in the interstitial connective tissues of pancreas and heart, unexpectedly numerous mesenchymal cells were found to exhibit especially strong labeling with [14C]A even after RNase treatment. Such cells had a large, round or ovoid, euchromatic nucleus and showed the blast-like appearance. The term mesenchymal cells was used to denote a special type of connective tissue cells that retain the potentiality of embryonic mesenchymal cells. Double labeling experiments using [14C]A and trypan blue by 7 daily injections (1 microCi/g body weight of [14C]A and 3 ml/rat of 0.5% aqueous solution of trypan blue each) disclosed that the mesenchymal cells exhibiting heavy [14C]A labeling did not ingest trypan blue at all. It was further revealed that, in addition to the mesenchymal cells, macrophages showing a remarkable trypan blue uptake were also labeled with [14C]A, though to a lesser extent than were the former cells. Moreover, transitional forms between the mesenchymal cells and macrophages were occasionally observed. The transitional forms were characterized by having the capacities not only for a fairly high rate of DNA synthesis but also of ingesting trypan blue, though to a slight extent. On the basis of the above findings, it can be stated that the mesenchymal cells showing heavy labeling with [14C]A are most likely the precursor cells of macrophages.

Adenine↗
PubMed1985

Raised serum hyaluronate levels in scleroderma: an effect of growth factor induced activation of connective tissue cells?

The circulating levels of hyaluronate were determined in 36 patients with scleroderma and in 36 control subjects matched for age and sex. The mean serum hyaluronate concentration in patients with progressive systemic sclerosis (n = 25) was 131 +/- 67 (SD) microgram/l and significantly greater (p less than 0.001) than that of the controls (mean level 49 +/- 21 (SD) microgram/l). Hyaluronate levels in patients with localised scleroderma (n = 4) were 141 +/- 47 (SEM) microgram/l and in patients with scleroderma-associated overlap syndromes (n = 7) 202 +/- 54 (SEM) microgram/l. The increase in serum hyaluronate probably reflected an enhanced synthesis or outflow of hyaluronate from the connective tissue, or both; it could not be explained by affection of the liver, which is the catabolic site of hyaluronate. The hyaluronate values were not related to certain serological indicators of inflammatory activity or to the extent of the skin lesions or the severity of internal organ manifestations. A positive correlation was noted between circulating platelet counts and hyaluronate levels (p less than 0.001). Plasma beta-thromboglobulin was measured in 15 of the patients with systemic sclerosis and found to correlate positively with platelet counts. Raised levels of beta-thromboglobulin were associated with the highest hyaluronate values. Platelet-derived growth factor, which stimulates connective tissue cells and is stored in the alpha-granules of platelets together with beta-thromboglobulin, was shown to enhance hyaluronate synthesis in fibroblast cultures. The results suggest an involvement in scleroderma of connective tissue activating substances released from platelets.

Cells, Cultured↗
PubMed1994

In vitro collagen synthesis by liver connective tissue cells isolated from schistosomal granulomas.

Hepatic injury elicits an excessive deposition of extracellular matrix probably due to a loss of control mechanisms in mesenchymal cells in fibrotic lesions, or a local activity of growth factors. To study collagen synthesis in an in vitro model of fibrotic lesions, we isolated liver connective tissue cells (LCTC) from murine schistosomal granulomas in C3H/HeN mice. Collagen was quantified in culture supernatants using a sirius red dye assay. LCTC and skin fibroblasts (SF) secreted similar amounts of collagen per cell and secretion was inversely proportional to the cell density. Cells cultured at low density (10,000 cells/cm2) secreted two- to three-times more collagen per cell when compared to cells grown in high-density cultures (60,000 cells/cm2). Collagen secretion was stimulated by transforming growth factor-beta (TGF-beta) in both cell lines, but the response of LCTC was detected from 1 ng/ml on, while SF responded only to higher concentrations (2.5 and 5 ng/ml). These data do not support the hypothesis that cells from fibrotic livers have lost the normal control mechanisms and suggest that their control is disturbed locally by the presence of peptide growth factors during the development of fibrosis.

Animals↗
PubMed1977

[Fluorescent-cytochemical study of the action of benz(a)pyrene on subcutaneous connective tissue cells during malignant transformation in vitro].

Alterations in the secondary DNA structure of cell nuclei of the rat's subcutaneous connective tissue exposed to benz(a)pyrene (BP) action have been revealed using the Roshlay fluorescent-cytochemical method in cultivating in vitro. Alterations in the luminescence of the acridin orange complex with DNA, i.e. displacement towards the red region of spectrum, indicates the changes in the secondary structure of DNA. The strongest action on the primary cultures were noted after the injection of carcinogen (on the 3rd day of explanation). The toxical effect was lower after a repeated BP injection (on the 10th and 20th days of explanation). Cells undergone malignization and transformation, due to the BP action on the primary explantates, were more resistant to carcinogen action than the normal cells. However, the spontaneously malignized cells were more sensitive to the BP action than the cells transformed under the carcinogen action.

Animals↗
PubMed1993

Immunohistochemical identification of myoepithelial, epithelial, and connective tissue cells in canine mammary tumors.

Fifty-eight formalin-fixed paraffin-embedded canine mammary tumors, 19 malignant and 39 benign, were used in this study. Tumors were obtained from dogs submitted for surgical resection of lesions at private veterinary practices in Brussels or from the surgery unit of the Faculty of Veterinary Medicine, University of Liège. Immunohistochemical evaluation was performed, using monoclonal antibodies directed against keratins 8-18 and 19, vimentin, desmin, and alpha-actin and polyclonal antibodies directed against high-molecular-weight keratins and S-100 protein. The main cell types, epithelial, myoepithelial, and connective, were identified, and myoepithelial cells represented the major component of most tumors, both benign and malignant. Myoepithelial cells had five patterns: resting and proliferative suprabasal cells, spindle and star-shaped interstitial cells, and cartilage. Reactivity to keratin 19, vimentin, alpha-actin, and S-100 protein suggested a progressive transformation from resting cells to cartilage. Epithelial cell reactivities were limited to keratins; only keratinized cells were positive for polyclonal keratins. Myofibroblasts were positive for both vimentin and alpha-actin, and connective tissue cells were positive for vimentin. Myoepithelial cells appeared to be the major component of carcinomas, justifying reevaluation and simplification of histomorphologic classifications, with a "pleomorphic carcinoma" group including all carcinomas except squamous, mucinous, and comedo carcinomas. Immunohistochemical evaluation, in addition to routine hematoxylin and eosin histopathologic evaluation is recommended for precise classification of canine mammary tumors.

Actins↗
PubMed1983

Effect of Mycoplasma pulmonis infection on protein and glycosaminoglycan synthesis of cultured connective tissue cells.

Human synovial cells, fetal skin fibroblasts and rat granulation tissue fibroblasts were experimentally infected with Mycoplasma pulmonis, a species identified as a contamination of cell cultures, and studied for collagen, total protein and glycosaminoglycan synthesis. Hyaluronic acid and sulfated glycosaminoglycan synthesis were stimulated in cultures where the infection reduced cell density, while they were retarded in cultures which had proliferated into higher density than the controls. An extra polypeptide with molecular weight of 20 kD was seen in [35S]methionine-labelled cells. Media of rat granulation tissue cells showed a shift of a 39-42 kD polypeptide to 33-36 kD position in [35S]methionine and [3H]proline labellings. Other minor changes were also noticed. Collagen synthesis or procollagen conversion to collagen were, however, not altered.

Animals↗
PubMed1991

Increased matrix gene expression by glucose in rat neural connective tissue cells in culture.

The effects of different glucose concentrations on the expression of extracellular matrix genes were examined in primary cell cultures initiated from sciatic nerves of nondiabetic Sprague-Dawley rats. The cells were incubated in medium containing 5.5, 15, or 25 mM D-glucose, and the expression of type I and IV collagens, laminin, and fibronectin genes was examined at mRNA steady-state levels by Northern hybridizations. Incubation of cell cultures, consisting of Schwann cells, perineurial cells, and fibroblasts, in high glucose concentrations (15 or 25 mM D-glucose) resulted in elevation of pro-alpha 1(IV), pro-alpha 2(IV), and pro-alpha 1(I) collagen chain and fibronectin mRNAs after only 3 days of incubation, whereas laminin B2 chain mRNA levels appeared unaltered. These observations suggest that hyperglycemia may partially contribute to basement membrane thickening in peripheral nerves of diabetic individuals by increasing the expression of genes coding for basement membrane components, e.g., type IV collagen.

Animals↗
PubMedDate not supplied

Identification of a common class of high affinity receptors for both types of porcine interleukin-1 on connective tissue cells.

Interleukin-1 (IL-1) is the name given to the polypeptides produced by activated mononuclear phagocytes which were originally defined as lymphocyte activating factors (LAF). Administration of IL-1 in vivo causes fever and synthesis of acute phase proteins. In vitro they have been shown to cause cartilage and bone resorption, and to stimulate fibroblasts and chondrocytes to make prostaglandins and latent collagenase. IL-1 has therefore been proposed to be an important inflammatory mediator and may be involved in the destruction of cartilage and bone that is a feature of rheumatoid arthritis and other inflammatory diseases of joints. We therefore looked for IL-1 receptors on connective tissue cells which might be targets for therapeutic intervention. Here we report the iodination, to high specific activity and with retention of full biological potency, of the two types of natural porcine IL-1. These ligands have been used to demonstrate high affinity dissociation constant (approximately 10(-10) M) specific binding sites on pig chondrocytes and synovial fibroblasts, human dermal fibroblasts and murine osteoblasts (3,000-5,000 sites per cell). Most interestingly, the two different Il-1 proteins show a similar affinity for a common class of receptors.

Animals↗