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Biomedical subjects

H Saari

Publications and source records attributed to H Saari.

At least 37 records · Page 2Linked to original sources
PubMed1992

Tetracycline inhibition identifies the cellular sources of collagenase in gingival crevicular fluid in different forms of periodontal diseases.

Tetracyclines have recently been shown to inhibit the activity of mammalian matrix metalloproteinases, i.e. type I collagenase (MMP-1) and type IV collagenase/gelatinase (MMP-2). The specificity of this effect, however, has not been examined in detail. In the present study, doxycycline (a clinically widely used commercial tetracycline) and 4-de-dimethylaminotetracycline (CMT-1, a chemically modified non-antimicrobial tetracycline) were tested, at a wide range of concentrations, for their ability to inhibit human neutrophil and fibroblast interstitial collagenases, which are distinct gene products, as well as collagenase in human gingival crevicular fluid (an inflammatory exudate in periodontal lesions) obtained from adult, juvenile and diabetic adult periodontitis patients. The concentrations of these two tetracyclines, required to inhibit 50% of the collagenase activity (IC50), were found to be 15-30 microM for purified human neutrophil collagenase as well as collagenase in gingival crevicular fluid of adult periodontitis patients and diabetic adult periodontitis patients, thus approximating in vivo therapeutic tetracycline levels. In contrast, the fibroblast collagenase and collagenase in gingival crevicular fluid of patients with juvenile periodontitis were relatively resistant to tetracycline inhibition: the IC50 for doxycycline and CMT-1 were 280 and 500 microM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Reactive oxygen species as regulators of human neutrophil and fibroblast interstitial collagenases.

The effects of various reactive oxygen species on latent human neutrophil and fibroblast-type interstitial collagenases were studied. Latent human neutrophil collagenases (proMMP-8) was efficiently activated by hypochlorous acid and hydrogen peroxide and less efficiently by the serine proteinases trypsin and chymotrypsin. Human plasmin and plasma kallikrein did not activate latent human neutrophil collagenase. The activation of latent human neutrophil collagenase by hypochlorous acid and hydrogen peroxide corresponded to the activation obtained with the other known non-proteolytic activators phenylmercuric chloride and gold thioglucose. The activation by hydrogen peroxide was inhibited by mannitol and desferoxamine, suggesting a localized Fenton-type reaction to be responsible for the generation of hydroxyl radical and/or hydroxyl radical-like reactive oxygen pathway of neutrophil procollagenase does not involve plasmin and plasma kallikrein, which are efficient proteolytic activators of latent fibroblast-type procollagenase (proMMP-1). Fibroblast procollagenase was also slightly activated by hypochlorous acid and gold thioglucose. Thus neutrophil procollagenase seems to prefer non-proteolytic means of activation and reactive oxygen species can be regarded as potent activators in vivo. Synovial-fluid neutrophils from rheumatoid arthritis patients were found to release collagenase in 30% active form when compared to same patients' peripheral blood neutrophils, which released collagenase in completely latent form. This may indicate that the triggering of neutrophil at the site of inflammation in vivo involves initial oxidative activation of collagenase upon the degranulation process.

Collagenases↗
PubMed1991

Effect of interleukin-1 on hyaluronate synthesis by synovial fibroblastic cells.

Interleukin-1 (IL-1) stimulates fibroblast-mediated hyaluronate (HA) synthesis in vitro. In the present study the degree of polymerization of such HA was studied using HPLC (high performance liquid chromatography) with a size exclusion column combined with 125I-HABP assay used to measure the HA concentration in various HA molecular weight fractions separated using HPLC. IL-1 stimulated HA was more polydisperse than that produced by resting fibroblasts with a molecular weight varying from more than 4 x 10(6) daltons to less than 7.1 x 10(3) daltons. This IL-1 effect may contribute to the low molecular weight HA produced by freshly explanted arthritic synovial tissue and to the low viscosity of arthritic synovial fluid in vivo.

Chromatography, High Pressure Liquid↗
PubMed1991

Substrate specificity and activation mechanisms of collagenase from human rheumatoid synovium.

Substrate specificity studies of collagenase extracted from human rheumatoid synovium suggest that synovial pannus tissue overlying articular cartilage may not be particularly active in degradation of cartilage type II collagen, which, considering the poor inherent healing capacity of the articular hyaline cartilage, may exert a protective function against inadvertant tissue damage. Rheumatoid synovial tissue was also used to establish synovial fibroblast cell lines. Treatment of these cells in monolayer cultures with IL-1 leads to collagenase gene activation, increased collagenase production and an almost complete autoactivation of secreted collagenase. Interleukin-1 also activated stromelysin gene suggesting this as a possible mechanism effecting autoactivation. Latent human fibroblast and macrophage collagenase purified from culture medium were efficiently activated by phenylmercuric chloride but also by gold thioglucose, gold sodium thiomalate and HCIO. These new observations support the Cys73 switch activation mechanism. In contrast to neutrophil collagenase, the activation by gold(I) compounds and HCIO was associated with a change in the apparent molecular weight of the fibroblast procollagenase. In addition, gold(I) compounds rendered collagenase more susceptible to thermal denaturation. Thus the fibroblast-type interstitial collagenase, probably derived from fibroblast- and macrophage-like synoviocytes, seems to provide the predominant collagenolytic potential in human rheumatoid synovial tissue. Furthermore, the conditions in synovitis tissue may be such as to favor at least initial activation of collagenase synthesized and secreted in situ.

Arthritis, Rheumatoid↗
PubMed1991

Collagenase reserves in polymorphonuclear neutrophil leukocytes from synovial fluid and peripheral blood of patients with rheumatoid arthritis.

Degradation of cartilage in rheumatoid arthritis (RA) may be in part due to release of collagenase from specific granules of polymorphonuclear neutrophil leukocytes (PMNs) during degranulation. We decided to study, not synovial fluid (SF) collagenase, but PMN collagenase reserves. PMN were isolated from parallel SF and peripheral blood (PB) samples obtained from 7-arthritis patients. PMNs were stimulated in vitro by tetradecanoyl-phorbol-13-acetate (TPA). Collagenase activity in the supernatant without and with phenylmercuric chloride activation was studied. Compared to PB PMNs, there was no consistent decrease in the total collagenase reserves in the inflammatory SF PMNs. This suggests that the release of collagenase in the inflammatory synovial fluid does not deplete SF PMNs of the collagenase synthesized at the myelocyte stage. The role of PMN collagenase in pathogenesis of cartilage destruction would then seem to be more dependent on local release and autoactivation at cartilage surface by adherent PMNs and not excessive collagenase release from free floating SF PMNs at single cell level. Furthermore, under the experimental conditions used the proportion of collagenase released in active form was higher in SF PMN specimens than in PB PMN specimens (p less than 0.01). The predominant collagenous component of adult cartilage, native type II collagen, was degraded by PMN collagenase as fast as native type I collagen. These findings suggest an important role for this enzyme in destruction of the free cartilage surface in RA.

Arthritis, Rheumatoid↗
PubMed1991

Hypochlorous acid induced activation of human neutrophil and gingival crevicular fluid collagenase can be inhibited by ascorbate.

Interstitial collagenase either obtained from human neutrophils by phorbol myristate acetate (PMA) induced degranulation or isolated from human gingival crevicular fluid was found to be activated by addition of an oxidative agent, hypochlorous acid (HOCl). Collagenase released by PMA stimulated neutrophils was completely in latent form but underwent partial autoactivation during 16 h incubation at 22 degrees C in the presence of soy bean trypsin inhibitor. The partial autoactivation was potentiated to complete activation of released collagenase after addition of exogenous HOCl. Ascorbate prevented this activation of neutrophil collagenase. Isolated human gingival crevicular fluid collagenase represented an apparent Mr of 70 kD in completely latent form, whereas 70/54 kD enzyme species were detected for partially autoactive form of the enzyme. Western blot analysis of gingival crevicular fluid using a polyclonal antibody raised against purified human neutrophil collagenase revealed the same 70/54 kD molecular forms of the enzyme. The latent gingival crevicular fluid collagenase was also activated by HOCl and this activation could be prevented by ascorbate. Activation of the 70 kD latent collagenase by HOCl as well as by other non-proteolytic activators such as an organomercurial compound (phenylmercuric chloride) and a gold(I) compound (gold thioglucose) was not associated with detectable changes in apparent Mr, whereas trypsin activation resulted in fragmentation of 70 kD enzyme to 54 kD species. Our results provide further evidence for the neutrophil origin of gingival crevicular fluid collagenase and suggest that, in addition to proteolytic activation, oxidative and antioxidative agents seem to be able to regulate neutrophil collagenase activity.

Ascorbic Acid↗
PubMed1991

Oxygen derived free radicals and synovial fluid hyaluronate.

High performance liquid chromatography with TSK 5000 PW or TSK 6000 PW size exclusion columns combined with a 125I labelled hyaluronic acid binding protein assay was used to study the effects of oxygen derived free radicals on synovial fluid hyaluronate. A continuous flux of free radicals was generated by the xanthine oxidase/hypoxanthine system. When the free radical flux was generated with xanthine oxidase/hypoxanthine in the presence of the iron chelator desferrioxamine and the hydroxyl radical scavenger mannitol a 30-50% decrease in hyaluronate peak was detected, but the molecular weight of synovial fluid hyaluronate remained almost unchanged as a result of reaction with superoxide radicals and hydrogen peroxide. When trace amounts of iron and EDTA were present in the reaction mixture depolymerisation of synovial fluid hyaluronate occurred, and it reached a final molecular weight of about 13,500 daltons. These results suggest that superoxide and hydroxyl radicals may have a different mode of action on synovial fluid hyaluronate. Superoxide radicals and hydrogen peroxide do not induce depolymerisation but, rather, change the molecular configuration of synovial fluid hyaluronate.

Carrier Proteins↗
PubMed1991

Effect of joint mobilization on serum hyaluronate.

Serum hyaluronate was monitored in volunteer patients with rheumatoid arthritis who were mobilized on day 1 at 7 am, but stayed at rest in bed on day 2 until mobilized at 11:30 am. 125I-hyaluronate binding protein assay disclosed a normal morning peak on day 1 but not on day 2. Instead, on day 2 transiently high hyaluronate levels were seen after 11:30 am. This suggests that joint mobilization affects serum hyaluronate. The morning peak may depend on the accumulation of hyaluronate in immobilized joints at night and its mobilization in the morning. High performance liquid chromatography with a size exclusion column used for fraction collection with 125I-hyaluronate binding protein assay showed that the serum hyaluronate in the morning peak is of relatively low molecular weight when compared to synovial fluid hyaluronate. This difference may be due to degradation of synovial fluid hyaluronate before its clearance into the blood stream.

Adult↗
PubMed1991

Serum zinc, copper and selenium in rheumatoid arthritis.

Rheumatoid arthritis (RA) is characterized by low serum Zn and high serum Cu. In multiple linear regression both were explained by disease activity parameters. It is suggested that interleukin-1 causes both changes by 1) increasing the metallothionein-mediated hepatic uptake to serum Zn and 2) upregulating ceruloplasmin (acute phase reactant) gene and synthesis in liver and subsequently the level of ceruloplasmin-Cu complexes in the blood. Cu absorption was diminished by zinc intake. Cu- and Zn-dependent erythrocyte SOD was increased in RA. In contrast to plasma GSHPx serum selenium was low in RA and this was associated with disease activity parameters.

Aging↗
PubMed1990

Serum baseline hyaluronate and disease activity in rheumatoid arthritis.

The baseline serum hyaluronate (HA) concentration from samples obtained five to seven hours after mobilization of the patient was quantified using a radiometric 125I-HA binding method in 58 patients with rheumatoid arthritis and compared with several clinical and laboratory parameters by means of stepwise multiple linear regression. In the age- and sex-adjusted model, the variables with independent predictive value for serum hyaluronate concentration were the erythrocyte sedimentation rate (ESR) and the joint score index measuring the extent of the synovial inflammation. The estimated synovial mass index and C-reactive protein values did not improve the fit of the model after ESR and joint score were entered, and were left out from the multiple regression equation. When ESR and joint score were studied in univariate regression analysis with serum hyaluronate, the coefficients were r = 0.492 and r = 0.397, and the P values were P less than 0.001 and P less than 0.005, respectively. It was concluded that the baseline hyaluronate level in serum is closely related to the synovitic activity of the rheumatoid inflammation and that measurement of serum hyaluronate is of value when the activity and extent of synovial inflammation is being assessed in patients with rheumatoid arthritis.

Adult↗
PubMed1990

Activation of latent human neutrophil collagenase by reactive oxygen species and serine proteases.

The ability of various reactive oxygen species and serine proteases to activate latent collagenase (matrix metalloproteinase-1) purified from human neutrophils was examined. Latent 70-75 kD human neutrophil collagenase (HNC) was efficiently activated by known non-proteolytic activators phenylmercuric chloride (an organomercurial compound) and gold thioglucose (Au(I)-salt). Corresponding degree of activation was achieved by reactive oxygen species including hypochlorous acid (HOCl), hydrogen peroxide (H2O2) and hydroxyl radical generated by hypoxanthine/xanthine oxidase (HX/XAO). The presence of trace amounts of iron and EDTA were necessary and even enhanced H2O2 induced activation of latent HNC. This activation could be abolished by an iron chelator desferrioxamine and a hydroxyl radical scavenger mannitol. HOCl induced activation of latent HNC was not affected by desferrioxamine and mannitol. Thus, these compounds do not inhibit the active/activated form of HNC. Latent HNC could also be activated by trypsin and chymotrypsin but not by plasmin and plasma kallikrein. The ability of mannitol and desferrioxamine to inhibit the H2O2-induced activation of HNC suggests the transition metal dependent Fenton reaction to be responsible for localized and/or site-specific generation of hydroxyl radical/hydroxyl radical -like oxidants to act as the activating oxygen species. Our results support the ability of myeloperoxidase derived HOCl to act as a direct oxidative activator of HNC and further suggest the existence of a new/alternative oxidative activation pathway of HNC involving hydroxyl radical.

Blood Proteins↗
PubMed1990

Reactive oxygen species and hyaluronate in serum and synovial fluid in arthritis.

Oxygen-derived free radicals (ODFR) depolymerized synovial-fluid (SF) hyaluronic acid (HA) when hypoxanthine/xanthine oxidase (HX/XAO) was used as the radical generator. The molecular-weight distribution of ODFR-induced SF HA degradation products was determined using high performance liquid chromatography (HPLC) with TSK 5000 PW or TSK 6000 PW size-exclusion columns and simultaneously using 125I-labelled hyaluronate-binding protein (125I-HABP) assay. The exposure of SF HA to hydroxyl-radical flux resulted in the formation of a degradation product having a molecular weight of 13.5 X 10(3) daltons, from which no further degradation was achieved. If the iron chelator desferrioxamine and hydroxyl-radical scavenger mannitol were present in the reaction mixture, the HA peak decreased by 30-50%, as a result of reaction with superoxide radical and hydrogen peroxide. These results show that superoxide radical and hydroxyl radical may have different modes of action on SF HA. The molecular-weight distribution of serum HA from patients with rheumatoid arthritis varied in different individuals and ranged between 275 X 10(3) and 650 X 10(3).

Arthritis, Rheumatoid↗
PubMed1990

Determination of concentration of hyaluronate in equine serum.

Concentration of hyaluronate (HA) in equine serum was determined by a recently developed specific radioassay. The mean +/- SD HA concentration in equine serum was 288 +/- 145 micrograms/L, was age dependent, and varied widely between horses (range, 190 to 760 micrograms/L). Light or moderate exercise increased serum HA concentration from baseline values by 1.5- to 3-fold. In all horses, serum HA concentration returned to or below the original resting values 1 and 2 hours after exercise.

Age Factors↗
PubMed1989

Isolation and characterization of hot particles from Chernobyl fallout in southwestern Finland.

Three types of activity composition have been found in airborne hot particles that were transported long distances from the Chernobyl accident. Their characterization is based on the analysis of single particles isolated from Pinus Sylvestris needles. The average activity of the particles was 130 Bq at the time of the accident. The most common type of particle contains the radioactive species 141Ce, 144Ce, 95Zr and 95Nb; the second type includes 103Ru and 106Ru along with the previous isotopes; and the third contains 103Ru and 106Ru only. Cesium-134 and -137 were present only in very small amounts. The activity composition of the Chernobyl reactor core fuel was similar to the composition of the first and second type particle; apparently the core fuel was only partially volatilized. The main bulk composition of the particles is shown to be U. The average aerodynamic size of the identified hot particles is 10 microns. The particles are rectangular or pentagonal in shape.

Accidents↗
PubMed1989

Determination of synovial fluid hyaluronate concentration and polymerisation by high performance liquid chromatography.

High performance liquid chromatography (HPLC) with a size exclusion column and ultraviolet monitoring was used to study the effect of synovial fluid hyaluronate concentration and degree of polymerisation on viscosity and mucin clot formation. Rotational viscometry measurements showed an exponential relation between the synovial fluid hyaluronate concentration and relative viscosity, the viscosity increasing particularly steeply with hyaluronate concentrations exceeding 2-2.5 mg/ml. The scattering of individual values observed around the expected curve was eliminated when both the hyaluronate concentration and its degree of polymerisation were taken into account. Hyaluronate concentration and degree of polymerisation also correlated with the quality of mucin clot, though only HPLC provided more detailed quantitative information about this association. Because HPLC allows reproducible and rapid simultaneous analysis of the synovial fluid hyaluronate concentration and the degree of polymerisation in small volumes of unprocessed samples it can be used in well equipped rheumatological units to replace other methods used previously.

Chromatography, High Pressure Liquid↗
PubMed1989

DNA synthesis in prolyl 4-hydroxylase positive fibroblasts in situ in synovial tissue. An autoradiography-immunoperoxidase double labeling study.

DNA synthesis in prolyl 4-hydroxylase (PH; EC 1.14.11.2) positive fibroblasts in situ in synovial tissue was studied using an autoradiography-avidin-biotin-peroxidase complex (ABC) double labeling. Fibroblasts in monolayer culture and in situ in synovial tissue were PH positive, whereas freshly isolated peripheral blood lymphocytes, monocytes, dendritic cells and granulocytes were PH negative. In rheumatoid arthritis (RA) 37 +/- 3 (22-56)% of all DNA synthesizing cells in situ were PH containing fibroblasts, whereas all DNA synthesizing cells in patients with meniscus lesion were PH positive. In both conditions, more than half of the self-replicating fibroblasts were located in the lining cell layer. This is probably not an artifact caused by insufficient penetration of 3H-thymidine because most of the DNA synthesizing lymphocytes were deep down in the synovial stroma. In RA 51 +/- 8 (17-88) PH positive fibroblasts in the S phase of the cell cycle were observed/3 mm2 synovial tissue, whereas the corresponding figure in meniscus patients was only 1 +/- 1 (0-5) (p less than 0.01). This suggests that the local fibroblasts in RA are activated, probably as a result of various fibroblast growth factors produced locally as a result of the inflammatory synovitis. In RA however, less than 1% of all local fibroblasts were self-replicating in situ, whereas labeling indices over 5% were not uncommon in RA synovial fibroblast cultures. This finding suggests that uncontrolled fibroblast proliferation is regulated in vivo by negative feedback mechanisms.

Arthritis, Rheumatoid↗