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N Forest

Publications and source records attributed to N Forest.

At least 73 records · Page 4Linked to original sources
PubMed1990

Effects of acidic fibroblast growth factor and epidermal growth factor on subconfluent fetal rat calvaria cell cultures: DNA synthesis and alkaline phosphatase activity.

The effects of acidic fibroblast growth factor (aFGF) and epidermal growth factor (EGF) were examined in subconfluent fetal rat calvaria cell cultures, in the presence of 2% serum. Maximal effect of aFGF and EGF on DNA synthesis measured by [3H]thymidine incorporation was observed after 18 h. aFGF stimulated DNA synthesis by 3.5-fold with an ED50 of 0.75 ng/ml while a 2.3-fold EGF stimulation was recorded with an ED50 of 0.067 ng/ml. 5-Bromo-2-deoxyuridine staining showed a higher stimulation of proliferation in the scattered cells than in the cell clusters. An 18 h aFGF or EGF treatment decreased alkaline phosphatase (ALP) activity by 40 and 23%, respectively, as compared with control cultures. This inhibition was more pronounced after 48 h in the presence of the effectors but no modification of the ALP electrophoretic mobility was observed. These data suggest that aFGF is a less potent mitogen than EGF and a higher inhibitor of ALP activity in fetal rat calvaria cell culture.

Alkaline Phosphatase↗
PubMed1990

Changes in cytokeratin expression in gingiva during inflammation.

Cytokeratins represent specific markers of certain pathways of epithelial differentiation. The purpose of this study was to describe the alterations of cytokeratin pattern and topographical distribution of individual cytokeratins in inflamed gingiva. Five healthy and 15 inflammatory samples of human gingiva were studied. From each biopsy, cryostat sections allowed histological staining, immunofluorescence microscopy using a battery of monoclonal antibodies to cytokeratins, and gel electrophoresis. The results show marked differences in cytokeratin expression by healthy epithelia as compared with inflamed gingiva: in suprabasal cell layers there were reductions or disappearance of cytokeratins 1, 2 and 10, 11--specific for terminal differentiation--and increased expression of cytokeratins 4 and 13, as well as--in basal and parabasal cell layers--expression of cytokeratin 19. These alterations might represent an adaptation of involved epithelia to the alterations brought about by the inflammatory process.

Adult↗
PubMed1990

Evolution of cytokeratin expression in developing human tooth germ.

Cytokeratin expression by the developing human enamel organ between the 10th and the 23rd gestational week was studied by indirect immunofluorescence microscopy technique using a panel of 15 monoclonal antibodies. The results showed that five antibodies (RKSE 60, Kk 8-60, EE 21-6, 6B10 and 1 C-7) were never reactive, that five antibodies (RCK 102, 42.39.13.1, Ks 19 and Pan 1-8) were always positive and that five antibodies (KB 37, RPN 11-62, Ks 13.1, Ks 8-12 and Ks 18.174) obtained or increased their positivity between weeks 12 and 13. It was concluded that a switch in cytokeratin expression occurred around the 12th-13th weeks. No further important change could be noticed after this period. So it is suggested that final cell differentiation was initiated at weeks 12-13.

Amelogenesis↗
PubMed1990

Effects of acidic fibroblast growth factor and epidermal growth factor on fetal rat calvaria cell cultures.

An inhibitory effect of alkaline phosphatase (LP) activity on short and long term fetal rat calvaria cell cultures was recorded with both acidic fibroblast growth factor (aFGF) and epidermal growth factor (EGF) at a concentration of 30 ng ml-1. This inhibition was well correlated with the nodule number on long term culture, except for EGF treatment in subconfluent cell culture.

Alkaline Phosphatase↗
PubMed1989

A comparative ultrahistochemical study of glycosaminoglycans with cuprolinic blue in bone formed in vivo and in vitro.

Histochemical and morphological studies have shown that proteoglygans (PG) are involved in mineralization process in vivo but such studies have not yet been conducted in vitro. A comparative histochemical study in electronic microscopy of the localization, organization, and morphology of the PG was performed with bones of calvaria rat formed in vivo and bone nodules formed in vitro from osteoblastic cells in culture. For this investigation, we used a cationic phthalocyanin dye, cuprolinic blue, in a critical electrolyte concentration which simultaneously stained the glycosaminoglycans and demineralized the bone. This histochemical technique demonstrated (1) osteoblast cells in vitro synthesized PG which were included in the matrix formed. (2) These PG were found in the calcified and uncalcified matrix both in vivo and in vitro. In the uncalcified matrix, PG were either free with a granular or rodlike structure or tightly connected to the periphery of the collagen fiber. Contrarily, in the calcified matrix, PG formed dense filamentous reticular patches between the collagen fibers. (3) Similarities in localization, organization, and morphology were noted in PG of bone formed de novo in vitro and in vivo with the exception of the mineralization front, where the staining in vivo compared with in vitro was faint or absent.

Animals↗
PubMed1989

A comparative biochemical and immunological analysis of cytokeratin patterns in the oral epithelium of the miniature pig and man.

In man, cytokeratin constitutes a family of 19 polypeptides that show different but distinct distribution patterns in the various epithelia. Changes in these patterns may occur during epithelial development and differentiation. The cytokeratin patterns in the oral mucosa of the miniature pig, an animal used in studies of wound healing, were investigated. Surgical biopsies were obtained from the gingiva, hard palate and alveolar mucosa of both man and pig. The cytokeratins were analysed by immunofluorescence, two-dimensional gel electrophoresis and by immunoblotting. Nine monoclonal antibodies were used to identify the different cytokeratin polypeptides in cryostat sections. Two-dimensional gel electrophoresis showed that pig oral mucosa contains at least 10 different polypeptides, five of the acidic type I and five of the basic type II cytokeratins. These were different from the human cytokeratin polypeptides and accordingly were designated P1-P10, according to their molecular weight and isoelectric mobility. Their molecular weight varied between 48 and 69 kdalton and the pHi varied between 5 and 7.3. Immunoblotting showed the monoclonal antibody Ks 13.1 (anticytokeratins Nos 13 and 14) to cross-react with the pig polypeptides P10 and P8. Immunolocalization showed that all the antibodies cross-reacted with the pig tissue except Ks 19.1 (anticytokeratin No. 19). It was possible to differentiate between pig alveolar mucosa, which expressed only P3, P4, P5, P8 and P10, and the gingival and hard palatal mucosae, which expressed all 10 polypeptides except P5. This distinction was made by antibody 6B10 (anticytokeratin No. 4), which reacted only with alveolar mucosa; antibody Ks 13.1, which strongly reacted with uncornified mucosa but weakly with cornified mucosa (gingiva and palate); and any of RKSE60, Kk 8.60 or EE21.6 (anticytokeratin No. 10, anticytokeratins Nos 10 and 11 and anticytokeratins Nos 1, 2, 10 and 11, respectively), which reacted strongly with cornified mucosa but weakly, if at all, with uncornified mucosa. These findings provide a baseline for studies on epithelial differentiation in the miniature pig such as in wound healing.

Animals↗
PubMed1989

Microcinematographic and autoradiographic kinetic studies of bone cell differentiation in vitro: matrix formation and mineralization.

Matrix formation and mineralization have been reported in vitro with cells isolated from rat calvaria bones by collagenase digestion (Nefussi et al., 1985). In the current study, kinetics of bone nodule formation and osteoblastic cell differentiation were studied in this in vitro system using an improved microcinematographic device and flash and follow-up labeling autoradiographic techniques. Microcinematographic analysis showed the formation of bone nodules within 24 h. The initial event observed was the change in the top cells layer which became alkaline phosphatase positive. Matrix synthesis occurred a few hours after this. The autoradiographic results demonstrated the formation of an integrated system where osteoblasts and osteocytes were active and synthesized a collagen matrix and mineralized it in a similar time sequence than in vivo.

Alkaline Phosphatase↗
PubMed1988

Compared roles of glucose, galactose and fructose as glycogen precursors during the acute response to insulin in cultured rat foetal hepatocytes.

1. The efficiency of the contribution of hexoses to basal- and stimulated-glycogenesis, when studied in cultured 18 day-old rat foetal hepatocytes in the presence of glucose, was as follows: galactose greater than glucose greater than fructose. 2. Glucose deprivation had opposite effects on the contributions of [14C]galactose (decreased) and [14C]fructose (increased) to glycogenesis, which occurred independently of insulin and were reversed by glucose concentrations as low as 30-100 microM. 3. The stimulation of glycogenesis by insulin measured with [14C]glucose (3.2-fold) was superior to that obtained with either [14C]galactose or [14C]fructose (2.7-fold in both cases), which revealed a specific beneficial effect of insulin on glucose contribution.

Animals↗
PubMed1987

Comparative effects of quinolones on human mononuclear leucocyte functions.

The effects of three quinoline derivatives--pefloxacin, ciprofloxacin and ofloxacin--were investigated in mitogen-stimulated human peripheral blood mononuclear leucocytes (MNL). At concentrations of 50 mg/l or more, pefloxacin, ciprofloxacin or ofloxacin significantly inhibited MNL proliferation in response to phytohaemagglutinin. This inhibition was more marked with ciprofloxacin than pefloxacin or ofloxacin. To determine the possible mechanism(s) involved in the inhibition of MNL proliferation following exposure to pefloxacin, ciprofloxacin or ofloxacin, we assessed (1) interleukin-1 (IL-1) activity in supernatants from monocytes treated with the quinolones and (2) the effects of 2-mercaptoethanol (2-ME) a thiol compound which acts as an antioxidant agent and the effect of indomethacin (INDO) an inhibitor of prostaglandin E2 synthesis. 2-ME and INDO did not prevent the decrease in the proliferation. IL-1 activity was shown to be decreased for the same range of antibiotic concentrations as observed for the inhibition of MNL proliferation. Cellular viability of the MNL or monocytes was not modified by any of the quinolones at the concentrations tested. Taken together, these results suggest that pefloxacin, ciprofloxacin and ofloxacin act as immunomodulators. The mechanism involved with the cascade of events that leads to the lymphocyte proliferation and the clinical relevance need further investigation.

Cell Survival↗
PubMed1986

Macrolides and immunity: effects of erythromycin and spiramycin on human mononuclear cell proliferation.

Macrolides are actively concentrated by leucocytes. The dose-effect responses of spiramycin (Sp) and erythromycin (Er) on phytohaemagglutinin (PHA) and pokeweed mitogen (PWM) stimulated human mononuclear leucocytes (MNL) were studied. Cell viability was not altered at any antibiotic concentration (1-100 mg/l). Both Sp and Er showed dose-related inhibition of the proliferative response of PHA and PWM stimulated MNL. Very marked effects were observed at high antibiotic concentrations and the effects observed at low concentrations (1-10), although small, were also significant. Similar results were observed for the mitogen PWM. A decrease in tritiated thymidine (3H-TdR) incorporation occurred only if Sp and Er were added during the first 8 h of culture. Sp and Er also induced a decrease in tritiated uridine (3H-UdR) uptake. These data suggest that Sp and Er interfered with an early event in the cell cycle. However Sp did not affect PHA binding to MNL. The clinical significance of these findings is discussed.

Cell Division↗
PubMed1986

Collagen expression during teratocarcinoma cell line-induced endochondral bone tumor.

Collagen immunotyping by indirect immunofluorescence was performed in order to investigate the sequential development of bone formation. Osseous tumors were obtained after subcutaneous injection of 3/A/1D-1 teratocarcinoma cell line into 129/Sv mice (Nicolas et al., 1980). Frozen sections of developing tumors were incubated with specific antibodies directed against Types I, II, III, IV, and IX collagens. On Day 9, the expression of Type I and Type III collagens was correlated with the proliferation of mesenchymal cells. From Day 10, chondrogenesis was characterized by the occurrence of cartilaginous collagens, Types II and IX, in the cartilage matrix. Type IV collagen was also detected in focal areas and revealed vascular invasion of the tumor. On Day 13, osteogenesis was demonstrated by the presence of Type I collagen in the bone matrix coating the surfaces. Immunolocalization of Type III collagen on the hemopoietic elements corresponded with the bone remodeling. The sequential transitions of collagen types confirm the development of an endochondral bone tumor. These results suggest that 3/A/1D-1 teratocarcinoma cell line constitutes a valuable system for in vitro study of endochondral bone formation and cell differentiation.

Animals↗
PubMed1985

Mineralization in vitro of matrix formed by osteoblasts isolated by collagenase digestion.

Osteoblasts from calvaria of 18-day-old fetal Sprague-Dawley rats were isolated using a dissecting procedure followed by collagenase digestion. Freshly isolated or previously frozen cells were cultured for up to 4 weeks in a Dulbecco's modified Eagle's medium supplemented with 10% fetal calf serum and 50 micrograms/ml ascorbic acid, with or without 10 mM beta-glycerophosphate. Most of the cells were alkaline phosphatase positive throughout the culture period and expressed a type-I collagen as assessed by immunofluorescence. Cells cultured in the presence of beta-glycerophosphate formed a matrix with type-I collagen in 7 days. The matrix underwent mineralization in less than 2 weeks. In the absence of beta-glycerophosphate, only the formation of a nonmineralized matrix was observed. Electron-microscopic examination revealed osteoblasts embedded in a dense network of collagen fibers, with a well-defined mineralization process in association with matrix vesicles. Scanning electron-microscopy showed that the matrix composed of layers of irregularly shaped spread cells with smooth surfaces trapped in a fiber matrix. No mineralization process was observed when rat skin fibroblasts were cultured under similar conditions. These data demonstrate the ability of enzymatically isolated osteoblasts cultured in the presence of beta-glycerophosphate to form bone in vitro, and that this process is similar to bone formation in vivo.

Alkaline Phosphatase↗
PubMed1985

Cytokeratin patterns of human oral epithelia: differences in cytokeratin synthesis in gingival epithelium and the adjacent alveolar mucosa.

Human oral mucosa includes various epithelia that are commonly classified as lining, masticatory, and specialized epithelia. Although adjacent tissues, the gingiva and alveolar mucosa represent two different types of epithelia: the gingiva is cornified and exhibits high rate ridges, whereas the mucosa does not normally cornify and exhibits a relatively smooth-contoured borderline between the epithelium and the underlying connective tissue. We examined the cytokeratin patterns of both epithelia using one- and two-dimensional gel electrophoresis. The gingiva expresses a great complexity of cytokeratins, including significant amounts of components nos. 1, 2, 5, 6, 10, 11, 13, 14, 16, and 17, as well as traces of cytokeratins nos. 4 and 15, i.e., a pattern similar to those of vaginal mucosa and epidermis containing proliferative keratinocytes. In contrast, the alveolar mucosa contains only two major cytokeratins, i.e., nos. 4 and 13, together with two minor amounts of cytokeratins nos. 5, 6, 14, and 17, thus resembling the patterns of certain other stratified, noncornified epithelia, such as the esophagus. Immunofluorescence microscopy using monoclonal antibodies to cytokeratins nos. 4 and 13 revealed the presence of these proteins in the suprabasal layers of alveolar mucosa, whereas in the gingiva, only certain small, suprabasal clusters of cells appeared to contain these cytokeratins. The cytoskeletal differences between gingival and alveolar mucosa are discussed in relation to the differences in their morphology and function, and with respect to pathological processes characteristic of these epithelia.

Cytoskeletal Proteins↗
PubMed1984

Cell multiplication and type II collagen production by rabbit articular chondrocytes cultivated in a defined medium.

The complexity and the variations in the efficiency of different batches of serum stimulated the preparation of a serum-free medium which could promote not only growth, but also the differentiation properties of rabbit articular chondrocytes in culture. The serum-free medium (SFM) developed in this study contained insulin, transferrin, Na-selenite, human fibronectin bovine serum albumin (BSA), brain growth factor (BGF) or fibroblast growth factor (FGF), hydrocortisone and multiplication stimulating activity (MSA). Primary or secondary cultures of chondrocytes in such a medium attained a proliferation rate equal to 70-80% of that obtained with chondrocytes grown in a serum control medium. The deletion of various factors from SFM indicates that BGF or FGF are the most stimulating of growth factors. Insulin was beneficial when used individually; when combined with BGF or FGF, they had a synergistic effect on cell proliferation. MSA seemed not to play any role in chondrocyte growth in culture. The SFM medium did not modify either the morphology or the progression of cells into the cell cycle. It moreover allowed the maintenance of the specific function of chondrocytes to synthesize type II collagen.

Animals↗