Enhanced synthesis of hyaluronic acid by human gingival fibroblasts exposed to human dental bacterial extract.
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Adult↗
Biomedical subjects
H Larjava
Publications and source records attributed to H Larjava.
A method for the hyaluronic acid synthetase assay in human skin.
A method for the determination of hyaluronic acid synthetase activity of human skin is described. Skin samples were crush-homogenized, and incubated with UDP-14C-glucuronic acid and UDP-N-acetylglucosamine in Tris-HCl-buffer containing MgCl2. After papain digestion of the samples, the 14C-labeled hyaluronic acid was separated in Sephadex G 50 chromatography. The radioactivity incorporated into hyaluronic acid was an expression of the activity of hyaluronic acid synthetase. This activity was found to be increased in skin biopsies obtained from psoriatic lesions and decreased after local treatment with potent corticoids.
Adrenal Cortex Hormones↗
The effect of human dental plaque on bone resorption and hyaluronic acid synthesis in in-vitro cultures of fetal rat calvaria.
Dental bacterial plaque affects bone demineralization both in vivo and in vitro. Since hyaluronic acid may play a role in demineralization, calcium release into the media as a measure of bone resorption was correlated with the synthesis of [3H]-glucosamine-labelled macromolecules in bone culture. The synthesis of glycosaminoglycans was determined by both a Millipore method and by DEAE-cellulose chromatography. Addition of plaque extract to the culture media stimulated both the synthesis and release of hyaluronic acid to the culture media, while stimulating calcium release. Thus, the bone-demineralizing effect of dental plaque seems to be associated to the induced synthesis of hyaluronic acid.
Animals↗
Arginine depletion in macrophage medium inhibits collagen synthesis by fibroblasts.
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Animals↗
Synthesis of hyaluronic acid and collagen in skin fibroblasts cultured from patients with osteogenesis imperfecta.
Collagen and hyaluronic acid syntheses were studied in skin fibroblast cultures from patients with osteogenesis imperfecta and age-matched controls by labeling the cultures either with [3H]proline and separating the collagenous proteins with DEAE- and CM-cellulose chromatographies, or double-labeling the cultures with [3H]glucosamine and [14C]glycine and separating radioactive hyaluronic acid from glycoproteins and sulphated proteoglycans by DEAE-cellulose chromatography. The activities of the cell layer hyaluronate synthesizing enzyme complex (hyaluronate synthetase) were also determined. The osteogenesis imperfecta cultures were classified into three variants on the basis of type III collagen synthesis. Type III collagen amounted to approx. 40--50% from total collagen in the first variety and approx. 25--30% in the second variety. No difference was noted in the ratio of type III collagen to total collagen in the third variety in comparison with control cultures. The radioactivities of 3H-labeled hyaluronic acid in DEAE-cellulose chromatograms were compared with those of the 14C-labeled proteins. The ratios ranged 9.2--17.3 in the cultures from the patients and 4.6--8.8 in the control cultures. Hyaluronate synthetase activities were 1.3--2.0-fold higher in the osteogenesis imperfecta cells than in their controls. Increased hyaluronic acid synthesis in skin fibroblasts correlated with the severity of the disease but not with the increase in type III collagen synthesis.
Adolescent↗
Cortisol decreases the synthesis of hyaluronic acid by human aortic smooth muscle cells in culture.
The effect of cortisol on the synthesis of glycosaminoglycans (GAGs) was studied in cultured human aortic smooth muscle cells. Cortisol, at a level slightly exceeding the physiological concentration (10(-6) M), decreased the synthesis of hyaluronic acid (HA) by 50% but had no significant effect on the synthesis of sulphated GAGs. The ratio of HA to sulphated GAGs decreased by 47%. These effects were most marked in the fraction secreted into the culture medium. Cortisol neither affected the activity of the hyaluronic acid synthesizing enzyme complex in a cell-free system nor the molecular weight distribution of hyaluronic acid. We suggest that the atherogenity of cortisol and stress may be associated with their effect on the synthesis of HA by the smooth muscle cells of the arterial wall.
Aorta↗
Improved application of the diphenylamine reaction for the determination of DNA.
An improved procedure is described for the separation and quantitation of DNA from biological samples. Following papain digestion, DNA was separated from other cell material with CdCl2 precipitation onto a glass-fiber filter and quantitated easily by the modified diphenylamine reaction.
Aniline Compounds↗
Release of lysosomal hydrolases from bone explants affected by dental plaque.
Lysosomal hydrolases as indicators of plaque-induced bone resorption in tissue culture were studied. Fetal rat bones cultured in a synthetic medium containing sonicated and filtrated human dental plaque were used as bones to be resorbed. Acid phosphatase and beta-glucuronidase were found to be the most suitable enzymes for studying the degradation rate of bone cell lysosomes. When dental plaque is used as a resorbing agent, special attention has to be paid to the fact that plaque extract contains similar lysosomal hydrolase activity. Plaque hydrolases in the present study were quite stable in culture medium. No significant adsorption of enzymes by fetal rat bones occurred while remarkable adsorption by synthetic hydroxyapatite was found. The present results indicate that dental plaque is able to release lysosomal hydrolases from bone explants. This release corresponds to the degree of resorption measured by 45Ca release from bones.
Acid Phosphatase↗
Serum lipoprotein composition, hormones, and the synthesis of glycosaminoglycans by human aortic smooth muscle cells.
The synthesis of hyaluronic acid (HA) and sulphated glycosaminoglycans (S-GAGs) by cultured human aortic smooth muscle cells (SMC) was measured in the presence of human sera with high LDL-cholesterol concentration (type IIA hyperlipoproteinemic patients) or high HDL-cholesterol concentration (marathon runners and lumberjacks). In addition, the effect of some hormones on GAG-synthesis was studied. As compared to normolipidemic controls, type IIA hyperlipoproteinemic sera decreased markedly the synthesis of HA without affecting the synthesis of S-GAGs. On the contrary, sera with high HDL-cholesterol concentration decreased the synthesis of S-GAGs causing a decrease in S-GAGs/HA ratio. Cortisol in concentrations slightly above the physiological level inhibited the synthesis of HA and increased the S-GAGs/HA ratio. Insulin, and interestingly also sex hormones (estradiol, progesterone, testosterone) had no clear effect on GAG-synthesis. It is known that there is an increased S-GAGs/HA ratio in early atherosclerotic lesions. Our results suggest that the determination of this ratio in SMC cultures provides an useful method of studying the atherogenity and antiatherogenity of various sera and hormones.
Aorta↗
Exogenous phospholipase C stimulates epithelial cell migration and integrin expression in vitro.
Phospholipase C secreted by bacterial pathogens has been identified as a virulence factor in several human diseases and has been implicated in impeding wound healing. The role of phospholipase C in the intracellular signal control of epithelial growth was studied in normal human skin keratinocytes cultured in conditions simulating aspects of wound healing. Bacillus cereus phospholipase C decreased cell-cell contact and increased cell migration resulting in disruption of the advancing epithelial sheet. Phospholipase C-induced migration was blocked by inhibitor of the phosphoinositol signal transduction pathway neomycin sulfate and protein kinase C inhibitor RO-31-8220. Induced migration was associated with elevated levels of matrix metalloproteinase-9 which, when blocked by tissue inhibitor of metalloproteinase-1, was accompanied by a loss of migration. Adhesion studies showed that phospholipase C treatment enhanced cell binding to fibronectin, vitronectin and collagen IV. Immunostained phospholipase C-stimulated cells cultured on fibronectin showed enhanced expression and relocation of the integrin subunits alpha(v), alpha5 and beta1. Confocal microscopy showed that phospholipase C-induced levels of integrin subunit beta1 were predominantly deposited on the basal surface of the cell apparently in focal contacts and associated with actin stress fibers. These results indicate that exogenous phospholipase C signaling from a bacterial source may play an important role in perturbing normal reepithelialization via altered expression of integrins and matrix metalloproteinase-9.
Bacillus cereus↗
Effect of sex chromosome aneuploidy on growth of human skin fibroblasts in cell culture.
Growth of human skin fibroblast lines with sex chromosome aneuploidy was studied in cell culture. Two lines were derived from individuals with 45,X and two from individuals with 47,XYY chromosome constitution. The aneuploid cell lines were compared with normal skin fibroblasts derived from age-matched same-sex siblings. To ensure similar conditions in culture, each study-control pair was treated simultaneously and equally in all steps. Growth in both 45,X cell cultures slowed down earlier than in control cultures. One of the 47,XYY cultures grew faster and the other at a similar speed to the control culture. Thus, the 45,X cell lines seemed to have lesser, and one of the 47,XYY cell lines greater, growth potential than the 46,XX and 46,XY cells, respectively. These differences in the final cell numbers may relate to changes in the rate of cell division of the aneuploid cell lines. However, the results do not support the hypothesis that an increasing number of sex chromosomes decreases the rate of cell division.
Adolescent↗