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| 2. |
- Eerola, Iiro, et al.
(författare)
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Type X collagen, a natural component of mouse articular cartilage : association with growth, aging, and osteoarthritis.
- 1998
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Ingår i: Arthritis and Rheumatism. - : John Wiley & Sons. - 0004-3591 .- 1529-0131. ; 41:7, s. 1287-1295
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To perform a systematic study on the production and deposition of type X collagen in developing, aging, and osteoarthritic (OA) mouse articular cartilage.METHODS: Immunohistochemistry was employed to define the distribution of type X collagen and Northern analyses to determine the messenger RNA levels as an indicator of the synthetic activity of the protein.RESULTS: Type X collagen was observed in the epiphyseal and articular cartilage of mouse knee joints throughout development and growth. Type X collagen deposition in the transitional zone of articular cartilage became evident toward cessation of growth, at the age of 2-3 months. The most intense staining for type X collagen was limited to the tidemark, the border between uncalcified and calcified cartilage. Northern analysis confirmed that the type X collagen gene is also transcribed by articular cartilage chondrocytes. Intense immunostaining was observed in the areas of OA lesions, specifically, at sites of osteophyte formation and surface fibrillation. Type X collagen deposition was also seen in degenerating menisci.CONCLUSION: This study demonstrates that type X collagen is a natural component of mouse articular cartilage throughout development, growth, and aging. This finding and the deposition of type X collagen at sites of OA lesions suggest that type X collagen may have a role in providing structural support for articular cartilage.
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| 3. |
- Helminen, Heikki, et al.
(författare)
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Kuormituksen vaikutus nivelrustoon [The effects of loading on articular cartilage].
- 1992
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Ingår i: Duodecim. - : Duodecim. - 0012-7183 .- 2242-3281. ; 108:12, s. 1097-1107
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Forskningsöversikt (refereegranskat)abstract
- Nivelen kuormitus on tärkeimpiä nivelruston aineenvaihduntaan ja rakenteeseen vaikuttavia fysiologisia tekijöitä. Kohtuullinen rytminen kuormitus lisää nuoren ihmisen nivelruston proteoglykaanipitoisuutta. Tämän vaikutuksesta rusto jäykistyy ja kasvaa paksuutta. Hyvin voimakas kuormitus ei aiheuta tällaista positiivista vastetta. Toisaalta nivelkuormituksen puuttuminen pienentää ruston proteoglykaanipitoisuutta ja heikentää kimmo-ominaisuuksia. Nämä surkastumismuutokset ovat suurimmaksi osaksi–elleivät kokonaan–korjautuvia. Kohtuullisella nivelkuormituksella voidaan siis ylläpitää ja parantaa nivelruston ominaisuuksia. Pitkäaikaisen liikkumattomuuden jälkeen nivelrusto on heikompi kuin normaalisti ja voi vaurioitua niveltä voimakkaasti kuormitettaessa. Siksi nivelen kuormitusta pitää lisätä toipumisvaiheessa vähitellen.
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| 5. |
- Kiviranta, Ilkka, et al.
(författare)
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Effects of mechanical loading and immobilization on the articular cartilage
- 1997
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Ingår i: Bailliere's Clinical Orthopaedics. - 1074-8814. ; 2:1, s. 109-122
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Forskningsöversikt (refereegranskat)abstract
- Articular cartilage provides nearly frictionless surfaces for joint movemants and reduces contact pressures, protecting the underlying suchondral bone from excess stress. The unique properties of articular cartilage are based on the interaction of the main components of the extracellular matrix: proteoglycans (PGs), collagen and interstitial fluid. Animal experiments and in vitro studies demonstrate that one of the most important regulators of the extracellular matrix metabolism is mechanical loading acting on the joints. Unloading and immobilization leads to PG depletion and softening of articular cartilage, increasing the risk of permanent cartilage degeneration. Moderate running exercise and increased weight bearing increases cartilage thickness, PG concentration and improves biomechanical properties of articular cartilage. With further increase in training intensity this positive influence of exercise disappears and cartilage shows changes analogous to immobilization of the joint, i.e. PG depletion and softening of the tissue. In humans most epidemiological studies have failed to prove the connection between running training and cartilage degeneration, but there is evidence that sports activities exposing joints to impact loading might increase the risk of osteoarthrosis.
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| 6. |
- Qu, Chengjuan, 1967-
(författare)
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Articular cartilage proteoglycan biosynthesis and sulfation
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Glucosamine (GlcN) and glucosamine sulfate (GS) have been used to treat the patients with osteoarthritis(OA) as a disease-modifying agent. Previousin vitro studies have focused on the effects of GlcN or GSon cartilage metabolism, whereas in vivo studies have investigated their potential for the treatment of OA. Although these results have raised promises of the disease-modifying effects of GlcN or GS, the cellular mechanisms behind these proposed effects are not clear. In general, the effectiveness of GS in thetreatment of OA as a symptomatic and as a disease-modifying agent is a matter of debate. Loss of proteoglycans (PGs) in OA could be partly due to deficient water binding e.g., by undersulfation of glycosaminoglycans (GAGs). In this study, the molar ratios of chondroitin sulfate (CS)disaccharide isoforms were analyzed with fluorophore-assisted carbohydrate electrophoresis to investigate the hypothesis that sulfate deficiency is involved with the development of bovine and human OA. Our present results indicate that the molar ratio of non-sulfated CS disaccharide in human samples was much lower than that detected in bovine samples, and it did not increase in human OA samples. Conversely, this ratio significantly decreased in bovine OA samples. Furthermore, the steady-state levels of aggrecan mRNA expression and sulfated GAG synthesis were analyzed by using Northern blot assay, quantitative real time reverse transcription polymerase chain reaction and[35S]sulfate incorporation analyses in bovine primary chondrocyte cultures. Aggrecan which is a large CS-PG of cartilage provides osmotic resistance for the cartilage helping it to absorb the compressive loads. Loss of PGs is a major cause of joint dysfunction and disability in OA. However, our results from 25 individual animals showed that none of the different forms of hexosamines, nor the GS salt, could stimulate aggrecan mRNA expression or GAG synthesis in bovine primary chondrocytes. Glucosamine is produced intracellularly from endogenous glucose, and is one of the basic sugar structures required for CS synthesis. It is converted to UDP-glucuronic acid (GlcA) and UDP-N-acetylgalactosamine (UDP-GalNAc) before use for the synthesis of CS polysaccharide chain. If exogenous GS is made available to the cultured cells, it can be directly incorporated into the CS synthesis by UDP-GalNAc via GlcN-6-phosphate bypassing fructose-6-phosphate. Thus, the levels of intracellular UDP-N-acetylhexosamines and UDP-GlcA were explored with reversed-phase high-performance liquid chromatography-electrospray ionization mass spectrometry in bovine primary chondrocytes to analyze whether a physiologically attainable level of GS could stimulate CS synthesis by increasing intracellular UDP-sugar levels. Our present results with the cells from nine individual animals did not support this hypothesis. In conclusion, bovine and human articular cartilage PGs were not undersulfated in the early stage of OA. Exogenous GS did not increase steady state levels of aggrecan mRNA expression, GAG synthesis or intracellular levels of nucleotide-activated precursors of GAG synthesis in bovine primary chondrocytes.
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| 7. |
- Säämänen, Anna-Marja, et al.
(författare)
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Effect of running exercise on proteoglycans and collagen content in the intervertebral disc of young dogs.
- 1993
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Ingår i: International Journal of Sports Medicine. - : Georg Thieme Verlag KG. - 0172-4622 .- 1439-3964. ; 14:1, s. 48-51
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Tidskriftsartikel (refereegranskat)abstract
- Collagen and proteoglycans in the intervertebral disc (LI-II) of young beagle dogs (age 55 weeks) were analyzed following a 15 weeks' daily 20 km running training on a treadmill with 15 degree uphill inclination. In nucleus pulposus no statistically significant alterations were found in the content of proteoglycans or collagen. In annulus fibrosus the total tissue wet weight and total amount of collagen (hydroxyproline) increased by 34-36% in the runners as compared to age-matched, untrained controls. Since the total amount of proteoglycans did not increase, the annulus fibrosus became relatively depleted of proteoglycans, as indicated by the 27% reduction in uronic acid concentration, expressed either per wet weight or hydroxyproline. The average molecular size of the remaining nonaggregating proteoglycans was larger, and there was also a trend towards increased proportion of proteoglycans aggregating with hyaluronan. Most of the chondroitin sulfate side chains were 6-sulfated (65-66%). Running did not alter the sulfation or length of the chondroitin sulfate chains. The decreased proteoglycan/collagen ratio in annulus fibrosus may result in altered mechanical properties of the tissue and reflects its adaptation to enhanced motion and stress.
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