| 1. |
- Arokoski, Jari, et al.
(författare)
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Nivelrikon etiopatogeneesi [Etiopathogenesis of osteoarthritis].
- 2001
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Ingår i: Duodecim. - : Duodecim. - 0012-7183 .- 2242-3281. ; 117:16, s. 1617-1626
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Tidskriftsartikel (refereegranskat)abstract
- Nivelrikon patofysiologia tunnetaan huonosti. Nykykäsityksen mukaan artroosissa ei olekyse nivelruston passiivisesta kulumisesta vaan biokemiallisesta tapahtumasarjasta, jossasoluväliaineen tuhoutuminen saa ylivallan rustoa korjaavista prosesseista. Nivelrikon alkuvaiheessarustosoluissa eli kondrosyyteissä aktivoituvat sekä ruston aineosien synteesitoimintaettä rustoa hajottavien entsyymien ilmentyminen ja niitä koodaavien geenientoiminta. Nivelrikko on koko nivelen sairaus, joka aiheuttaa muutoksia niin nivelrustossa,luussa kuin pehmytosissakin. Vallitsevan käsityksen mukaan nivelrikko käynnistyynivelruston pinnallisesta vyöhykkeestä. On myös esitetty, että nivelalueen altistuminenliialliselle kuormitukselle aiheuttaisi ensin rustonalaisen luun paksunemisen ja jäykkenemisen,mikä puolestaan altistaisi nivelruston suuremmille kuormittaville voimille. Riskitekijöistätärkeimpiä ovat ikääntyminen, liikapaino, niveleen kohdistuvat vammat ja ruumiillisentyön aiheuttama liikarasitus. Perinnöllisten tekijöiden osuus on myös merkittävä.Ruston kollageenien rakennevirheiden tiedetään altistavan nivelrikolle.
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| 2. |
- Haapala, Jussi, et al.
(författare)
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Coordinated regulation of hyaluronan and aggrecan content in the articular cartilage of immobilized and exercised dogs.
- 1996
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Ingår i: Journal of Rheumatology. - : Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 23:9, s. 1586-1593
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study the influence of joint loading and immobilization on articular cartilage hyaluronan concentration and histological distribution in the knee joints of young dogs subjected to 11 weeks' immobilization by splinting, and 15 weeks' running exercise at a rate of 40 km/day.METHODS: The amount of hyaluronan in articular cartilage was determined by a competitive binding assay using a biotinylated hyaluronan binding complex (HABC) of aggrecan and link protein. Histologic sections were stained for the localization of hyaluronan with the HABC probe. Extracted proteoglycans were characterized by sodium dodecyl sulfate agarose gel electrophoresis.RESULTS: Immobilization significantly reduced the concentration of hyaluronan in all sites studied (tibial and femoral condyles, patellar surface of femur). The proportion of hyaluronan to total uronic acid (mainly from aggrecan) remained unchanged because of a concurrent decrease in aggrecan. The ratio of hyaluronan and aggrecan remained constant also in runners. The staining pattern of free hyaluronan in the tissue sections and the electrophoretic mobility of the extracted proteoglycans were not affected by the different loading regimes.CONCLUSION: Reduced joint loading due to splint immobilization significantly decreases both hyaluronan and aggrecan in the articular cartilage. The remarkably parallel changes in aggrecan and hyaluronan content suggest that joint loading exerts a coordinated influence on their metabolism.
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| 3. |
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| 4. |
- Hyttinen, Mika, et al.
(författare)
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Age matters : collagen birefringence of superficial articular cartilage is increased in young guinea-pigs but decreased in older animals after identical physiological type of joint loading.
- 2001
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Ingår i: Osteoarthritis and Cartilage. - : Saunders Elsevier. - 1063-4584 .- 1522-9653. ; 9:8, s. 694-701
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To compare responses of the collagen network and glycosaminoglycans (GAGs) of articular cartilage to physiological type of joint loading in young growing and adult mature guinea-pigs.DESIGN: 10- and 44-week-old guinea-pigs were accustomed to treadmill running for 3 weeks. Thereafter the animals ran 2500 m/day, 5 days a week, for 15 weeks. Articular cartilage specimens from knee joints were collected at 28 and 62 weeks. Osteoarthritis (OA) prevalence and severity was evaluated by aid of light microscopy. The degree of collagen fibril network organization and content was analyzed with quantitative polarized light microscopy. The local concentration of GAGs was determined from cartilage sections with digital densitometry after safranin-O staining.RESULTS: In the young guinea-pigs, running increased up to 24% the optical retardation of polarized light by collagen in the superficial articular cartilage of femur, indicating either a higher degree of fibril assembly and organization or increased amount of collagen, or both. In contrast, in the adult mature animals the optical retardation decreased almost 50% after joint loading (P< 0.01-0.001). Running did not increase cartilage fibrillation. Significant changes in GAG content of cartilage were not found either in the young or adult mature runners.CONCLUSIONS: Increased birefringence of the superficial articular cartilage after joint loading in young guinea-pigs can be interpreted to be a sign of improved and decreased birefringence in older animals a sign of worsened property of the collagen network. It can be suggested therefore that joint loading strengthened the collagen network in the young runners. It can be hypothesized further that with time the inferior property of the collagen network predisposes the older runners to earlier OA than in controls.
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| 5. |
- Inkinen, Ritva, et al.
(författare)
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Hyaluronan distribution in the human and canine intervertebral disc and cartilage endplate.
- 1999
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Ingår i: The Histochemical Journal. - 0018-2214 .- 1573-6865. ; 31:9, s. 579-587
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Tidskriftsartikel (refereegranskat)abstract
- A biotinylated complex of aggrecan G1-domain and link protein was used to characterize the distribution of hyaluronan in paraffin-embedded sections of adult human and canine intervertebral disc and cartilage endplate. Limited chondroitinase ABC and trypsin digestions of the sections before staining was utilized to expose hyaluronan potentially masked by aggrecan. Hyaluronan concentration and hyaluronan to uronic acid ratio in different parts of the discs were measured as a background for the histological analysis. Hyaluronan staining was strong in the nucleus pulposus and inner parts of annulus fibrosus of both species, corroborated by biochemical assays of the same compartments. Particularly in human samples, hyaluronan in the interterritorial matrix of nucleus pulposus and annulus fibrosus was readily accessible to the probe without enzyme treatments. In contrast, the cell-associated hyaluronan signal was enhanced after trypsin or limited chondroitinase ABC-treatment of the sections, suggesting that pericellular hyaluronan was more masked by aggrecan than in the distant matrix. A puzzling feature of canine cartilage endplate cells was their intensive cell-associated hyaluronan signal, part of which appeared intracellular. Hyaluronan was abundant between the collagenous lamellae in annulus fibrosus, perhaps important in the plasticity of this tissue.
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| 6. |
- Jortikka, Matti, et al.
(författare)
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The role of microtubules in the regulation of proteoglycan synthesis in chondrocytes under hydrostatic pressure.
- 2000
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier. - 0003-9861 .- 1096-0384. ; 374:2, s. 172-180
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Tidskriftsartikel (refereegranskat)abstract
- Chondrocytes of the articular cartilage sense mechanical factors associated with joint loading, such as hydrostatic pressure, and maintain the homeostasis of the extracellular matrix by regulating the metabolism of proteoglycans (PGs) and collagens. Intermittent hydrostatic pressure stimulates, while continuous high hydrostatic pressure inhibits, the biosynthesis of PGs. High continuous hydrostatic pressure also changes the structure of cytoskeleton and Golgi complex in cultured chondrocytes. Using microtubule (MT)-affecting drugs nocodazole and taxol as tools we examined whether MTs are involved in the regulation of PG synthesis in pressurized primary chondrocyte monolayer cultures. Disruption of the microtubular array by nocodazole inhibited [(35)S]sulfate incorporation by 39-48%, while MT stabilization by taxol caused maximally a 17% inhibition. Continuous hydrostatic pressure further decreased the synthesis by 34-42% in nocodazole-treated cultures. This suggests that high pressure exerts its inhibitory effect through mechanisms independent of MTs. On the other hand, nocodazole and taxol both prevented the stimulation of PG synthesis by cyclic 0. 5 Hz, 5 MPa hydrostatic pressure. The drugs did not affect the structural and functional properties of the PGs, and none of the treatments significantly affected cell viability, as indicated by the high level of PG synthesis 24-48 h after the release of drugs and/or high hydrostatic pressure. Our data on two-dimensional chondrocyte cultures indicate that inhibition of PG synthesis by continuous high hydrostatic pressure does not interfere with the MT-dependent vesicle traffic, while the stimulation of synthesis by cyclic pressure does not occur if the dynamic nature of MTs is disturbed by nocodazole. Similar phenomena may operate in cartilage matrix embedded chondrocytes.
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| 7. |
- Király, Kari, et al.
(författare)
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Safranin O reduces loss of glycosaminoglycans from bovine articular cartilage during histological specimen preparation.
- 1996
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Ingår i: The Histochemical Journal. - : Chapman & Hill. - 0018-2214 .- 1573-6865. ; 28:2, s. 99-107
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Tidskriftsartikel (refereegranskat)abstract
- The ability of Safranin O, added to fixation and decalcification solutions, to prevent the escape of glycosaminoglycans (GAGs) from small cartilage tissue blocks during histological processing of cartilage has been studied. GAGs in the fixatives and decalcifying solutions used and those remaining in the 1 mm3 cubes of cartilage were assayed biochemically. The quantity of GAGs remaining in the cartilage cubes were determined from Safranin O-stained sections using videomicroscopy or microspectrophotometry. A quantity (10.6%) of GAGs were lost during a conventional 4% buffered formaldehyde fixation (48 h) and a subsequent decalcification in 10% EDTA (12 days) at 4 degrees C. Roughly one-quarter of the total GAG loss occurred during the 48 h fixation, and three-quarters during the 12 days of decalcification. Inclusion of 4% formaldehyde in the decalcification fluid decreased the loss of GAGs to 6.2%. The presence of 0.5% Safranin O in the fixative reduced this loss to 3.4%. When 0.5% Safranin O was included in the fixative and 4% formaldehyde in the decalcification solution, Safranin O staining of the histological sections increased on average by 13.5%. After fixation in the presence of 0.5% Safranin O, there was no difference in the staining intensities when decalcification was carried out in the presence of either Safranin O or formaldehyde, or both. It took 24 h for Safranin O to penetrate into the deep zone of articular cartilage, warranting a fixation period of at least this long. In conclusion, the addition of Safranin O to the fixative and either Safranin O or formaldehyde in the following decalcification fluid, markedly reduces the loss of GAGs from small articular cartilage explants during histological processing. However, for immunohistochemical studies, Safranin O cannot be included in the processing solutions, because it may interfere.
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| 8. |
- Lammi, Mikko, 1961-, et al.
(författare)
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Expression of reduced amounts of structurally altered aggrecan in articular cartilage chondrocytes exposed to high hydrostatic pressure.
- 1994
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Ingår i: Biochemical Journal. - : Portland Press Ltd.. - 0264-6021 .- 1470-8728. ; 304, s. 723-730
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Tidskriftsartikel (refereegranskat)abstract
- The effect of hydrostatic pressure on proteoglycan (PG) metabolism of chondrocyte cultures was examined using a specially designed test chamber. Primary cultures of bovine articular chondrocytes at confluence were exposed for 20 h to 5 and 30 MPa continuous hydrostatic pressures and 5 MPa hydrostatic pulses (0.017, 0.25 and 0.5 Hz) in the presence of [35S]sulphate. Northern blot analyses showed that chondrocyte cultures used in this study expressed abundant mRNA transcripts of aggrecan, typical of chondrocytes, but not versican. The cultures also expressed biglycan and decorin. Enzymic digestions with keratanase and chondroitinases AC, ABC and B and subsequent SDS/agarose gel electrophoresis confirmed the synthesis of aggrecans and small dermatan sulphate PGs. The continuous 30 MPa pressure reduced total PG synthesis by 37% as measured by [35S]sulphate incorporation, in contrast to the 5 MPa continuous pressure which had no effect. The high static pressure also reduced total [3H]glucosamine incorporation by 63% and total [14C]leucine incorporation by 57%. The cyclic pressures showed a frequency-dependent stimulation (0.5 Hz, 11%) or inhibition (0.017 Hz, -17%) of [35S]sulphate incorporation. Aggrecans secreted under continuous 30 MPa pressure showed a retarded migration in 0.75% SDS/agarose gel electrophoresis and they also eluted earlier on Sephacryl S-1000 gel filtration, indicative of a larger molecular size. The increased size was consistent with an increase of average glycosaminoglycan chain length as determined by Sephacryl S-300 gel filtration. No change in aggrecan size was observed with the lower (5 MPa) static or cyclic pressures. Continuous 30 MPa hydrostatic pressure slightly reduced the steady-state mRNA level of aggrecan, in parallel with the decline in PG synthesis measured by [35S]sulphate incorporation. The results demonstrated that high hydrostatic pressure could influence the synthesis of PGs, especially of aggrecans, in chondrocytes both at the transcriptional and translational/post-translational levels.
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| 9. |
- Lammi, Mikko, 1961-
(författare)
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Influences of in vivo and in vitro loading on the proteoglycan synthesis of articular cartilage chondrocytes
- 1993
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this study, the biosynthesis of proteoglycans (PGs) was examined in articular cartilage of canine hip joint after long-distance running experiment and in bovine chondrocyte cultures during in vitro loading with hydrostatic pressure. In addition, new assays were developed for more sensitive quantitation of glycosaminoglycans (GAGs) and PGs.Anterior (weight-bearing) and posterior (less weight-bearing) areas of the femoral head from young beagles were labeled after long-term, longdistance running exercise. Total sulpahte incorporation rates were determined and distribution of of the incorporated sulphate in the tissue was localized by quantitative autoradiography. Concentration and extractability of the PGs were determined, and PG structures were studied by gel filtration, agarose gel electrophoresis, and chemical determinations. In the less weight-bearing area, the amount of extractable PGs was decreased, simultaneously with an increased concentration of residual GAGs in the tissue after 4M GuCl extraction. In the weight-bearing area, no marked alterations were noticed. The congruency of the femoral head seems to protect the cartilage from untoward alterations that occur in the femoral head condyles subjected to the same running program.The effect of hydrostatic pressure on PG metabolism of chondrocyte cultures was examined during 20 hours' exposure of chondrocytes to 5 and 30 MPa pressures. The continuous 30 MPa pressure reduced total PG synthesis by 37 % as measured by [35S]sulphate incorporation, in contrast to the 5 MPa which had no effect. Continuous 30 MPa hydrostatic pressure also reduced the steady-state mRNA level of aggrecan. The cyclic pressures showed a frequency dependent stimulation (0.5 Hz, + 11 %) or inhibition (0.017 Hz, -17 %). Aggrecans secreted under continuous 30 MPa pressure showed a retarded migration in 0.75 % SDS-agarose gel electrophoresis and also eluted earlier on Sephacryl S-1000 gel filtration, indicative of larger molecular size. The results demonstrate that high hydostatic pressure can influence the synthesis of PGs in chondrocytes both at the transcriptionl and translational/posttranslational levels.
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| 10. |
- Lin, Chun-Yu, 1976-
(författare)
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The role of hyaluronan and its CD44 receptor in inflammation and cancer
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hyaluronan, an important extra-cellular matrix molecule, was thought to be interstitial connecting glue decades ago. However, recent evidence has revealed that hyaluronan and its binding proteins also play crucial roles in various pathophysiological conditions in humans, including inflammation and infection.Study I focused on dengue virus infection and found that elevated serum hyaluronan levels during early infection phase was an independent predictor for occurrence of warning signs, and thus severe dengue. High circulating levels of the viral non-structural protein 1 (NS1) correlated with high concentrations of serum hyaluronan. NS1 exposure decreased the expression of CD44 in differentiating endothelial cells impairing the integrity of vessel-like structures and promoted the synthesis of hyaluronan in dermal fibroblasts and endothelial cells in synergy with dengue-induced pro-inflammatory mediators. Perturbed hyaluronan-CD44 interactions enhanced endothelial permeability through modulation of VE-cadherin and cytoskeleton re-organization, and exacerbated the NS1-induced disruption of endothelial integrity. Study II reports a negative correlation between the expression of genes encoding hyaluronan synthase HAS2, its natural antisense transcript HAS2-AS, the chromatin modulating factor HMGA2 and transforming growth factor-β (TGFβ), and survival of patients with invasive breast cancer. TGFβ induction of Hmga2, Has2as and Has2 in mouse mammary epithelial cells, and synthesis of hyaluronan were accompanied with activation of Akt and Erk1/2 MAP-kinase signaling and were required for breast cancer cell motility. Importantly, the hyaluronan receptor Cd44, but not Hmmr, was required for TGFβ-mediated epithelial-mesenchymal transition phenotype. Has2as was found to contribute to the maintenance of stem cell factors and breast cancer stemness. Study III explored the physical interaction between the inhibitor of the apoptosis-stimulating protein of p53 (iASPP) and the hyaluronan receptor CD44. The CD44 standard isoform (CD44s), but not the variant isoform, bound to iASPP via the ankyrin-binding domain in CD44s. iASPP was required for hyaluronan-induced CD44-dependent migration and adhesion of fibroblasts. CD44 altered the sub-cellular localization of the iASPP-p53 complex; thus, ablation of CD44 promoted translocation of iASPP from the nucleus to the cytoplasm, resulting in increased formation of a cytoplasmic iASPP-p53 complex in fibroblasts. Overexpression of iASPP decreased the level of intracellular reactive oxygen species, while overexpression of CD44 increased. Knock-down of CD44s, in the presence of p53, led to increased cell growth and cell density of fibroblasts by suppression of p27 and p53.In summary, we investigated the interaction of hyaluronan and its transmembranous receptor, CD44, as well as the modulation of hyaluronan synthesis, in several different pathophysiological conditions.
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