Search PubMed⌕ Search

Biomedical subjects

H Larjava

Publications and source records attributed to H Larjava.

At least 91 records · Page 5Linked to original sources
PubMed1987

Fibronectin fragmentation induced by dental plaque and Bacteroides gingivalis.

Degradation of fibronectin (FN) by subgingival and supragingival plaque and Bacteroides gingivalis (Bg) was studied in vitro. The degradation of FN by both types of plaque was relatively rapid, continuous but incomplete. Some differences were found between supra- and subgingival samples. Supragingival plaque extracts produced several FN fragments of 110-180 kd during short incubations of 15-60 min. The predominant fragment after overnight incubation was a 110 kd polypeptide. With subgingival plaque extract a more extensive degradation of FN was noted. The main degradation product was a 120 kd fragment after overnight incubation. Several peptide fragments were released from fibronectin by Bg extracts. Their molecular size was different from those produced by trypsin, elastase or dental plaque. When cell extracts of Bg were fractionated by high performance liquid chromatography, three separate peaks of fibronectin degrading activity were obtained. Two of those peaks also contained trypsin-like enzyme activity. The degradation of fibronectin and the subsequent formation of biologically active peptides may have many effects in periodontal pockets. These may include modifying effects on plaque growth and wound healing.

Bacteroides↗
PubMed1987

Inhibition of gingival fibroblast growth by Bacteroides gingivalis.

Human gingival fibroblasts were exposed in culture to cell extracts of different black-pigmented Bacteroides species, and their growth was monitored by determining thymidine uptake and counting cells. Of the Bacteroides species tested (B. gingivalis, B. asaccharolyticus, and B. intermedius), B. gingivalis gave the extract with the strongest inhibitory effect on fibroblast thymidine uptake. Linear inhibition reaching 80% of the control level was obtained with a dose of 100 micrograms of B. gingivalis extract protein per ml. The effect of B. asaccharolyticus resembled that of B. gingivalis, but even at the highest dose tested B. intermedius had only a slight inhibitory effect. When fibroblasts were counted after 2- and 4-day exposures to B. gingivalis extracts, a clear depression in the number of fibroblasts was found. The effects of extracts obtained from early and late growth phases of B. gingivalis cultures were similar. A fraction of B. gingivalis consisting essentially of lipopolysaccharides (LPSs) was obtained by degrading the extract proteins with proteinase K. Silver staining of polyacrylamide gels revealed a LPS pattern with a molecular mass ranging from 37 to 60 kilodaltons. This LPS-rich fraction caused inhibition of thymidine uptake by gingival fibroblasts similar to that caused by the native extract alone. Thus, the inhibition of gingival fibroblast growth by B. gingivalis appeared to be LPS mediated. This inhibitory effect of B. gingivalis on oral fibroblast growth may be a virulence factor of this bacterium.

Bacteroides↗
PubMed1987

Abnormal dermal proteoglycan in aspartylglycosaminuria: a possible mechanism for ultrastructural changes of collagen fibrils in a glycoprotein storage disorder.

Changes in the structure and organization of collagen fibrils were recently described in the skin of aspartylglycosaminuria patients. The skin of the patients contained a normal amount and distribution of glycosaminoglycans, but the dermatan sulfate of aspartylglycosaminuria skin was more sensitive to chondroitinase AC digestion, resulting in unsaturated 4-sulfated disaccharides which were not detected in controls. Isolated dermatan sulfate chains as well as the chains present in the intact core protein synthesized by skin fibroblasts from an aspartylglycosaminuria patient were also digestible with chondroitinase AC, while those of a control fibroblast culture could be digested with chondroitinase ABC only. This is indirect evidence for abnormal epimerization of dermatan sulfate in the skin of aspartylglycosaminuria patients, which may be associated with the changes in collagen fibril formation.

Acetylglucosamine↗
PubMed1987

Alterations in scleroderma fibroblast surface glycoproteins associated with increased collagen synthesis.

Fibroblasts were cultured from affected and unaffected skin sites of 6 patients with localized scleroderma. As a parameter of fibroblast activation, collagen synthesis and cellular pro alpha 1(I)collagen mRNA levels were measured. Cell surface glycoproteins were labelled with the periodate/borohydride method and fractionated electrophoretically. A distinct reduction in the relative amount of surface glycoproteins in the 120 kDa region was observed in two affected cell lines producing increased amounts of collagen and in one affected cell line with normal collagen production when compared to unaffected fibroblast lines. Other, non-systematic alterations in the surface glycoproteins of the affected cell lines were also detected. Compared to unaffected and healthy control fibroblasts no alterations in the surface protein profiles were seen in the other three affected cell lines. These cells did not show an increase in collagen production either. The results suggest that the activation of collagen synthesis found in scleroderma fibroblasts might be connected with alterations in the normal cell surface glycoprotein pattern.

Adult↗
PubMed1986

Changes in the expression of cell surface sialoglycoproteins during transition of human monocytes into macrophages.

Cell surface sialoglycoproteins of human mononuclear phagocytes in different maturation stages were labelled by the periodate/borohydride method and separated by SDS-polyacrylamide gel electrophoresis. The main surface glycoproteins of peripheral blood monocytes had molecular masses of 115 and 95 kDa. During in vitro transition into adherent macrophages, the monocyte-characteristic surface glycoproteins disappeared. Most of the changes in the surface glycoprotein pattern occurred during the first 24 h and after 96 h the changes were completed. The major sialoglycoproteins of the macrophage cell surface had molecular masses of 130 and 55 kDa. The macrophage cell surface showed further changes when cultured in the presence of synovial fluid (10%). These results may reflect the in vivo maturation of monocytes into tissue macrophages. In synovium, tissue-derived factors may also take part in differentiation.

Cell Membrane↗
PubMed1986

Oral health of patients with insulin-dependent diabetes mellitus.

Oral health, the amount of salivary Streptococcus mutans and lactobacilli, and the flow rate, pH and buffer capacity of paraffin-stimulated whole saliva were analyzed in 35 adult diabetic patients and their age- and sex-matched non-diabetic, clinically healthy controls. All patients had insulin-dependent diabetes (IDDM) with a mean (+/- SD) duration of 14.0 +/- 9.1 yr. The prevalence of dental caries was as high in the diabetic group as in the controls but the past caries experience was remarkably lower in those individuals whose diabetes had started at a very early age (less than or equal to 7 yr). In agreement with the clinical data, the salivary levels of cariogenic microorganisms were of the same order of magnitude in both study groups. However, the relative proportion of S. mutans from the total cultivable aerobic microflora was significantly higher (P less than 0.01) in diabetics compared to the controls. The other studied salivary parameters did not differ between the groups. Remarkable individual differences were observed in the correlation between glucose levels of blood and whole saliva among diabetics. In spite of the noncariogenic dietary habits, the adult diabetic patients seem to be at least as susceptible to dental caries as non-diabetics, probably due to the leakage of glucose from blood into the oral cavity.

Adolescent↗
PubMed1986

Collagens in neurofibromas and neurofibroma cell cultures.

Neurofibromas contain approximately 30-50% collagen of their lipid-free dry weight, which is about half of the value of skin but approximately twice that described for peripheral nerve endoneurium. Immunohistochemical stainings indicate that neurofibromas contain types I, III, IV, and V collagens and fibronectin. Most of the neurofibroma cells are type IV collagen and S-100 protein positive, which provides immunohistochemical evidence that neurofibromas are mostly composed of Schwann cell-like cells. The proteoglycan/collagen ratio is 4 to 10 times higher in the neurofibromas than in the surrounding dermal tissue. This would explain the typical soft consistency of the neurofibromas and may contribute to a favorable milieu for tumor growth. Pure fibroblastic cell cultures are obtained from neurofibromas after repeated passages. The cultured cells synthesized type I and III collagens and fibronectin, indicating that these cells are important in the production of the fibrous connective tissue proteins in neurofibromas.

Cells, Cultured↗
PubMed1986

Immunoglobulins and innate antimicrobial factors in whole saliva of patients with insulin-dependent diabetes mellitus.

We analyzed the flow rate and composition of paraffin-stimulated whole saliva samples from 35 adult diabetic patients and their age- and sex-matched, non-diabetic, clinically healthy controls. All patients had insulin-dependent diabetes (IDDM) with a mean (+/- S.D.) duration of 14.0 +/- 9.1 years. The saliva analysis included the quantitation of total protein, amylase, immunoglobulins (isotypes A, G, and M), and the non-antibody, innate antimicrobial factors (lysozyme, lactoferrin, salivary peroxidase, myeloperoxidase, thiocyanate, and hypothiocyanite). The whole saliva samples from diabetic patients had significantly higher amounts of IgA (p less than 0.001) and IgG (p less than 0.05) than did the controls. No differences between the study groups were observed in flow rate, protein content, amylase activity, or IgM. The levels of innate defense factors were similar in both study groups except for salivary peroxidase, which was higher (p less than 0.02) among diabetics than among controls. Our results indicate that the antimicrobial defense capacity of whole saliva is not impaired in diabetic patients.

Adolescent↗
PubMed1986

Distribution and biosynthesis of connective tissue components by synovial fibroblasts cultured with mononuclear inflammatory cells.

Two main cell types, spindle-shaped and large flattened cells, were identified in fibroblast cultures from synovial tissue explants. Type I collagen and fibronectin were visualized by indirect immunofluorescence and the hyaluronic acid coat around the cells by the erythrocyte exclusion method. Collagen was detected as intracellular granules which varied greatly in their number with no correlation to the cell shape. Hyaluronic acid coat was seen only around the spindle-shaped cells, whereas the intercellular fibronectin was found throughout the cultures. Morphological alterations in synovial fibroblasts were detected when subjected to mononuclear cells isolated from peripheral blood. The fibroblast became thinner and branched and stellate cells with numerous extensions appeared. Hyaluronic acid synthetase activity increased by about 50% and was obviously related to the appearance of the stellate cells, whereas no evident change was detected in collagen synthesis. The stellate cells were full of collagen granules. The hyaluronic acid coat around these cells did not differ from that around normal spindle-shaped cells. Synovial fibroblasts cocultured with mononuclear cells lost the intercellular fibronectin network, but other main cell surface glycoproteins studied with the periodate-borohydride method and electrophoresis remained unaltered in spite of morphological alterations.

Arthritis, Rheumatoid↗
PubMed1985

Urinary glycosaminoglycans in aspartylglycosaminuria: evidence for disturbed proteoglycan metabolism.

An abnormal excretion pattern of urinary glycosaminoglycans was found in patients with aspartylglycosaminuria, a lysosomal storage disorder of glycoprotein metabolism. The mean daily GAG excretion, measured as uronic acids, was within the reference range, though higher than that of matched controls. However, in AGU patients fractionation of isolated urinary glycosaminoglycans revealed markedly increased proportions of heparan sulfate which were nearly 50% of the total glycosaminoglycans. The changes observed in glycosaminoglycan excretion reflect abnormalities of proteoglycan metabolism. They offer further evidence for the presence of a generalized connective tissue disorder in aspartylglycosaminuria. Increase of heparan sulfate may also refer to abnormalities of glycosaminoglycan metabolism in the central nervous system with a possible role in the neurological manifestations of the disorder.

Acetylglucosamine↗
PubMed1984

The protective effect of peroxidase and thiocyanate against hydrogen peroxide toxicity assessed by the uptake of [3H]-thymidine by human gingival fibroblasts cultured in vitro.

The hypothiocyanite ion (OSCN-) is the principal oxidation product of the salivary peroxidase-thiocyanate (SCN-)-hydrogen peroxide antimicrobial system. Supplementation of human saliva in vitro and in vivo with low amounts (less than 1.0 mM) of hydrogen peroxide increase the concentration of salivary OSCN- (in vivo up to 0.3 mM). Elevated concentrations of OSCN- are strongly antimicrobial and may therefore be protective against dental caries. However, as OSCN- is a highly-reactive oxidizing agent, its possible toxic effect on human cells was studied using gingival fibroblasts as target cells. Concentrations of OSCN- (up to 300 microM) had no effect on [3H]-thymidine incorporation into the cells. However, fibroblasts were sensitive to peroxide so that 100 microM of H2O2 caused over 80 per cent reduction in [3H]-thymidine incorporation. The toxicity of H2O2 could be entirely prevented by adding lactoperoxidase and SCN- to the cell culture before the addition of peroxide. Thus, conversion of toxic H2O2 to non-toxic OSCN- in fibroblast culture by lactoperoxidase and SCN- suggests a dual role for the salivary peroxidase system: protection of human cells from H2O2 toxicity and antimicrobial action against oral pathogens. Furthermore, the elevated concentrations of OSCN- which produce inhibition of bacterial metabolism did not damage human cells.

Adult↗
PubMed1984

Chemotaxis and surface glycoproteins of neutrophil granulocytes from patients with juvenile periodontitis.

Neutrophil granulocytes were isolated from the peripheral blood of eight patients with juvenile periodontitis and their healthy controls. The cells were radioactively surface-labelled by the periodate-sodium boro-[3H]-hydride method and their surface glycoproteins studied by polyacrylamide gel electrophoresis and isoelectric focusing. The chemotaxis and chemokinesis were studied against casein. The results indicate that the cells of the patients have normal surface glycoprotein structure and do not show defect in chemotaxis.

Adolescent↗