| 1. |
- Lammi, Pirkko, et al.
(författare)
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Site-specific immunostaining for type X collagen in noncalcified articular cartilage of canine stifle knee joint.
- 2002
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Ingår i: Bone. - : Elsevier. - 8756-3282 .- 1873-2763. ; 31:6, s. 690-696
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Tidskriftsartikel (refereegranskat)abstract
- Type X collagen is a short-chain collagen that is strongly expressed in hypertrophic chondrocytes. In this study, we used an immunohistochemical technique exploiting a prolonged hyaluronidase unmasking of type X collagen epitopes to show that type X collagen is not restricted to calcified cartilage, but is also present in normal canine noncalcified articular cartilage. A 30 degrees valgus angulation procedure of the right tibia was performed in 15 dogs at the age of 3 months, whereas their nonoperated sister dogs served as controls. Samples were collected 7 and 18 months after the surgery and immunostained for type X collagen. The deposition of type X collagen increased during maturation from age 43 weeks to 91 weeks. In the patella, most of the noncalcified cartilage stained for type X collagen, whereas, in the patellar surface of the femur, it was present mainly in the femoral groove close to cartilage surface. In femoral condyles, the staining localized mostly in the superficial cartilage on the lateral and medial sides, but not in the central weight-bearing area. In tibial condyles, type X collagen was often observed close to the cartilage surface in medial parts of the condyles, although staining could also be seen in the deep zone of the cartilage. Staining for type X collagen appeared strongest at sites where the birefringence of polarized light was lowest, suggesting a colocalization of type X collagen with the collagen fibril arcades in the intermediate zone. No significant difference in type X collagen immunostaining was observed in lesion-free articular cartilage between controls and dogs that underwent a 30 degrees valgus osteotomy. In osteoarthritic lesions, however, there was strong immunostaining for both type X collagen and collagenase-induced collagen cleavage products. The presence of type X collagen in the transitional zone of cartilage in the patella, femoropatellar groove, and in tibial cartilage uncovered by menisci suggests that it may involve a modification of collagen fibril arrangement at the site of collagen fibril arcades, perhaps providing additional support to the collagen network.
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| 2. |
- Brage, Monica, et al.
(författare)
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Osteoclastogenesis is decreased by cysteine proteinase inhibitors.
- 2004
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Ingår i: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 34:3, s. 412-24
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Tidskriftsartikel (refereegranskat)abstract
- The effects of cystatin C and other cysteine proteinase inhibitors on osteoclast formation and differentiation have been investigated. Cystatin C decreased osteoclast formation stimulated by parathyroid hormone (PTH), 1,25(OH)2-vitamin D3 or interleukin-6 (IL-6) (in the presence of its soluble receptor) as assessed by the number of tartrate-resistant acid phosphatase (TRAP+) multinucleated cells in mouse bone marrow cultures. The inhibitory effect was associated with decreased mRNA expression for the calcitonin receptor as well as decreased number of specific binding sites for 125I-calcitonin, and without any effect on the mRNA expression of receptor activator of nuclear factor kappaB (NF-kappaB) ligand (RANKL). Similarly, the cysteine proteinase inhibitors leupeptin, E-64 and benzyloxycarbonyl-Phe-Ala-diazomethane (Z-FA-CHN2) decreased PTH-stimulated formation of TRAP+ multinucleated cells and binding of 125I-calcitonin. A peptidyl derivative synthesized to mimic part of the proteinase-binding site of cystatin C (benzyloxycarbonyl-Arg-Leu-Val-Gly-diazomethane, or Z-RLVG-CHN2) also decreased PTH-stimulated osteoclast formation. In a 9-day culture, addition of cystatin C during the last 5 days was sufficient to cause substantial inhibition of osteoclast formation. Cystatin C-induced decrease of osteoclast formation was associated with enhanced number of F4/80-positive macrophages and increased mRNA expression of the macrophage receptor c-fms in the bone marrow culture. Osteoclast formation in mouse bone marrow cultures as well as in mouse spleen cell cultures, stimulated by macrophage colony-stimulating factor (M-CSF) and RANKL was also decreased by different cysteine proteinase inhibitors. In addition, cystatin C inhibited M-CSF/RANKL induction of calcitonin receptor mRNA in spleen cell cultures. The inhibitory effect by cystatin C in spleen cells was associated with decreased mRNA expression of RANK and the transcription factor NFAT2. It is concluded that cysteine proteinase inhibitors decrease formation of osteoclasts by interfering at a late stage of pre-osteoclast differentiation.
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| 3. |
- Brand, H S, et al.
(författare)
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Family 2 cystatins inhibit osteoclast-mediated bone resorption in calvarial bone explants.
- 2004
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Ingår i: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 35:3, s. 689-96
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Tidskriftsartikel (refereegranskat)abstract
- Osteoclastic bone resorption depends on the activity of various proteolytic enzymes, in particular those belonging to the group of cysteine proteinases. Biochemical studies have shown that cystatins, naturally occurring inhibitors of these enzymes, inhibit bone matrix degradation. Since the mechanism by which cystatins exert this inhibitory effect is not completely resolved yet, we studied the effect of cystatins on bone resorption microscopically and by Ca-release measurements. Calvarial bone explants were cultured in the presence or absence of family 2 cystatins and processed for light and electron microscopic analysis, and the culture media were analyzed for calcium release. Both egg white cystatin and human cystatin C decreased calcium release into the medium significantly. Microscopic analyses of the bone explants demonstrated that in the presence of either inhibitor, a high percentage of osteoclasts was associated with demineralized non-degraded bone matrix. Following a 24-h incubation in the presence of cystatin C, 41% of the cells were adjacent to areas of demineralized non-degraded bone matrix, whereas in controls, this was only 6%. If bone explants were cultured with both PTH and cystatin C, 60% of the osteoclasts were associated with demineralized non-degraded bone matrix, compared to 27% for bones treated with PTH only (P < 0.01). Our study provides evidence that cystatins, the naturally occurring inhibitors of cysteine proteinases, reversibly inhibit bone matrix degradation in the resorption lacunae adjacent to osteoclasts. These findings suggest the involvement of cystatins in the modulation of osteoclastic bone degradation.
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| 4. |
- Brechter, Anna Bernhold, et al.
(författare)
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Kinin B1 and B2 receptor expression in osteoblasts and fibroblasts is enhanced by interleukin-1 and tumour necrosis factor-alpha. Effects dependent on activation of NF-kappaB and MAP kinases.
- 2008
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Ingår i: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 43:1, s. 72-83
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Tidskriftsartikel (refereegranskat)abstract
- Pro-inflammatory mediators formed by the kallikrein-kinin system can stimulate bone resorption and synergistically potentiate bone resorption induced by IL-1 and TNF-alpha. We have shown that the effect is associated with synergistically enhanced RANKL expression and enhanced prostaglandin biosynthesis, due to increased cyclooxygenase-2 expression. In the present study, the effects of osteotropic cytokines and different kinins on the expression of receptor subtypes for bradykinin (BK), des-Arg10-Lys-BK (DALBK), IL-1beta and TNF-alpha have been investigated. IL-1beta and TNF-alpha enhanced kinin B1 and B2 receptor binding in the human osteoblastic cell line MG-63 and the mRNA expression of B1 and B2 receptors in MG-63 cells, human gingival fibroblasts and intact mouse calvarial bones. Kinins did not affect mRNA expression of IL-1 or TNF receptors. EMSA showed that IL-1beta and TNF-alpha activated NF-kappaB and AP-1 in MG-63 cells. IL-1beta stimulated NF-kappaB via a non-canonical pathway (p52/p65) and TNF-alpha via the canonical pathway (p50/p65). Activation of AP-1 involved c-Jun in both IL-1beta and TNF-alpha stimulated cells, but c-Fos only in TNF-alpha stimulated cells. Phospho-ELISA and Western blots showed that IL-1beta activated JNK and p38, but not ERK 1/2 MAP kinase. Pharmacological inhibitors showed that NF-kappaB, p38 and JNK were important for IL-1beta induced stimulation of B1 receptors, and NF-kappaB and p38 for B2 receptors. p38 and JNK were important for TNF-alpha induced stimulation of B1 receptors, whereas NF-kappaB, p38 and JNK were involved in TNF-alpha induced expression of B2 receptors. These data show that IL-1beta and TNF-alpha upregulate B1 and B2 receptor expression by mechanisms involving activation of both NF-kappaB and MAP kinase pathways, but that signal transduction pathways are different for IL-1beta and TNF-alpha. The enhanced kinin receptor expression induced by the pro-inflammatory cytokines IL-1beta and TNF-alpha might be one important mechanism involved in the synergistic enhancement of prostaglandin formation caused by co-treatment with kinins and one of the two cytokines. These mechanisms might help to explain the enhanced bone resorption associated with inflammatory disorders, including periodontitis and rheumatoid arthritis.
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| 5. |
- Conaway, H. H., et al.
(författare)
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Activation of dimeric glucocorticoid receptors in osteoclast progenitors potentiates RANKL induced mature osteoclast bone resorbing activity
- 2016
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Ingår i: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 93, s. 43-54
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Tidskriftsartikel (refereegranskat)abstract
- Glucocorticoid (GC) therapy is the greatest risk factor for secondary osteoporosis. Pathogenic mechanisms involve an initial increase in bone resorption followed by decreased bone formation. To gain a better understanding of the resorptive activity of GCs, we have used mouse bone marrow macrophages (BMM) to determine if GCs can directly modulate RANKL stimulated osteoclast formation and/or activity. In agreement with previous studies, experiments performed in plastic wells showed that GCs (dexamethasone, hydrocortisone, and prednisolone) inhibited osteoclast number and size during the initial phases of RANKL stimulated osteoclastogenesis; however, in prolonged cultures, decreased apoptosis was observed and escape from GC induced inhibition occurred with an enhanced number of osteoclasts formed, many with an increased area. When BMM cells were seeded on bone slices, GCs robustly enhanced RANKL stimulated formation of resorption pits and release of CTX without affecting the number or size of osteoclasts formed and with no effect on apoptosis. Stimulation of pit formation was not associated with increased life span of osteoclasts or an effect on mRNA expression of several osteoclastic or osteoclastogenic genes. The potentiation of RANKL induced CTX release by dexamethasone was significantly less in BMM cells from mice with conditional knockout of the osteoclastic glucocorticoid receptor and completely absent in cells from GRdim mice, which carry a point mutation in one dimerizing interface of the GC receptor. These data suggest that: 1. Plastic is a poor medium to use for studying direct effects of GCs on osteoclasts 2. GCs can enhance bone resorption without decreasing apoptosis, and 3. A direct enhancement of RANKL mediated resorption is stimulated by the dimeric GC-receptor. © 2016 Elsevier Inc.
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| 6. |
- Eklund, Fredrik, et al.
(författare)
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Bone mass, size and previous fractures as predictors of prospective fractures in an osteoporotic referral population.
- 2009
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Ingår i: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 45:4, s. 808-813
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Tidskriftsartikel (refereegranskat)abstract
- The influence of bone mass, bone size and previous low energy fractures upon prospective fractures has not been investigated in a referral osteoporotic population. We investigated the association between bone mass, bone size, previous fractures, body constitution, and prospective validated fractures in 5701 women and 1376 men, aged 30 years and older. Bone mass measurements of the femoral neck were collected at a single study center in Sweden. Most of the subjects were measured on suspicion of osteoporosis. Data on validated low energy retrospective and prospective fractures in the cohort were collected from the corresponding health care district. Bone mineral density (BMD, g/cm(2)) and estimated volumetric BMD (vBMD, g/cm(3)) were shown to be good independent predictors for fracture in both women and men (Hazard ratio per standard deviation decrease (HR)=1.27-1.52, p<0.05). Bone size did not predict prospective fractures in either sex (HR=0.91-0.99, p>0.05), and bone size completely explained the higher BMD in men than in women. In women, retrospective low energy fractures (HR=1.78, p<0.001) and height (HR=1.02, p=0.006) were additional independent predictors of osteoporotic fractures after adjusting for age and BMD. In conclusion, we show that in a large osteoporotic referral population, age, BMD and previous fractures are independent predictors of prospective low energy fractures. These results add additional strength to the recent change in focus towards a multivariate analysis when assessing the future risk of fracture.
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| 7. |
- Frysz, Monika, et al.
(författare)
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The influence of adult hip shape genetic variants on adolescent hip shape : Findings from a population-based DXA study
- 2021
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Ingår i: Bone. - : Elsevier. - 8756-3282 .- 1873-2763. ; 143
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Hip shape is a well-recognized risk factor for hip osteoarthritis (OA) and hip fracture. We aimed to investigate whether the genetic variants known to be associated with adult hip shape were also associated with adolescent hip shape.Methods: Hip DXA scans, obtained in offspring from the Avon Longitudinal Study of Parents and Children (ALSPAC) at two time points (mean ages 13.8 and 17.8 years), were used to quantify hip morphology using a 53-point Statistical Shape Model (SSM). Principal component analysis was used to generate hip shape modes (HSMs). Genetic variants which had previously shown genome-wide significant association with specific HSMs in adults were tested for association with the same HSMs in adolescents (at each timepoint separately) using SNPTEST v2.Results: Complete genotypic and phenotypic data were available for 3550 and 3175 individuals at 14 and 18 years, respectively. The strongest evidence for association with adolescent hip shape was for a variant located near SOX9 (rs2158915) with consistent effects across both time points for HSM1 (age 14: beta -0.05, p = 9.9 x 10(-8); age 18: -0.05, p = 3.3 x 10(-6)) and HSM5 (age 14: beta -0.07, p = 1.6 x 10(-4); age 18: -0.1, p = 2.7 x 10(-6)). There was also strong evidence of association between rs10743612 (near PTHLH) and HSM1 (age 14: 0.05, p = 1.1 x 10(-5); age 18: 0.04, p = 0.003) and between rs6537291 (near HHIP) and HSM2 (age 14: -0.06, p = 0.001; age 18: -0.07, p = 0.001) across both time points. The genes with the strongest associations with hip shape in adolescents, (SOX9, PTHLH and HHIP) are known to be involved in endochondral bone formation. HSM1 indicates narrower aspect ratio of the upper femur, whereas both HSM2 and HSM5 reflect variation in the femoral head size and femoral neck width, features previously found to be related to the risk of OA in later life. The SOX9 locus has previously been found to associate with increased risk of hip fracture.Conclusion: In conclusion, variants implicated in endochondral bone formation appear to consistently influence hip shape between adolescence and adulthood, including those aspects related to risk of hip OA and/or fracture in later life.
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| 8. |
- Granholm, Susanne, et al.
(författare)
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Osteoclast progenitor cells present in significant amounts in mouse calvarial osteoblast isolations and osteoclastogenesis increased by BMP-2
- 2013
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Ingår i: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 52:1, s. 83-92
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Tidskriftsartikel (refereegranskat)abstract
- Enzymatically released cells from neonatal mouse calvarial bones are frequently used as primary mouse osteoblasts for in vitro studies. We, here, report that although these cells lack mRNA expression of the osteoclastic genes Calcr, Acp5 and Mmp-9 at early time points after their isolation, these transcripts are gradually upregulated when the calvarial osteoblast cultures are differentiated to more mature osteoblasts in long term cultures. Similarly, Calcr, Acp5, Mmp-9, as well as Rank and Nfatc1 mRNA expressions are robustly increased when the osteoblast cultures were induced to differentiate by treatment with bone morphogenetic protein (BMP-2). The increased Calcr mRNA resulted in functionally active calcitonin receptors. Enhanced osteoblastic differentiation was associated with increased Rankl mRNA expression and decreased Opg and Cfs1 mRNA expression. Treatment of the osteoblastic cells with BMP-2 or RANKL, either on plastic dishes or bone slices, resulted in the formation of multinucleated tartrate-resistant acid phosphatase positive cells, which were able to excavate resorption pits and release CTX from the bones. In contrast, increased osteoblastic differentiation induced by BMP-2 in the mouse calvarial osteoblastic cell line MC3T3-E1 was not associated with increased mRNA expression of Calcr, Acp5, Rank, c-Fms or Oscar. Interestingly, Ctsk mRNA was increased during osteoblastic differentiation in both mouse calvarial osteoblast cultures and in MC3T3-E1 cultures. Also osteoblasts isolated from mouse long bones by outgrowth from explant cultures were contaminated with osteoclast progenitors able to differentiate into bone resorbing osteoclasts. These data indicate that mouse calvarial osteoblast cultures contain osteoclast progenitor cells, which will be differentiated along the osteoclastic lineage during osteoblastic differentiation. Moreover, the data show that BMP-2 not only stimulates osteoblastic differentiation but can also induce osteoclastogenesis through increased RANKL.
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| 9. |
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| 10. |
- Johansson, Jonas, 1984-, et al.
(författare)
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Objectively measured physical activity is associated with parameters of bone in 70-year-old men and women
- 2015
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Ingår i: Bone. - : Elsevier. - 8756-3282 .- 1873-2763. ; 81, s. 72-79
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Tidskriftsartikel (refereegranskat)abstract
- As the world's population ages, the occurrence of osteoporosis-related fractures is projected to increase. Low areal bone mineral density (aBMD), a well-known risk factor for fractures, may be influenced by physical activity (PA). In this cross-sectional study, we aimed to investigate potential associations between objective measures of PA and bone properties, in a population-based cohort of 1228 70-year-old men and women. We measured volumetric BMD (vBMD, mg/cm3) together with cross-sectional area (CSA, mm2) by peripheral quantitative computed tomography at sites located 4% and 66% in the distal–proximal trajectory at the tibia and radius. We also measured aBMD (g/cm2) by dual energy X-ray absorptiometry at the femoral neck, lumbar spine (L1–L4) and radius. Participants wore triaxial accelerometers for 7 consecutive days to obtain objective estimates of PA. The intensity of the objective PA was divided into light (100–1951 counts/min [CPM]), moderate (1952– 5724 cpm) and vigorous (≥5725 cpm). Maximal accelerations for the anterior–posterior (z), medio-lateral (x), and vertical (y) axes were also separately assessed. Associations were investigated using bivariate correlations and multiple linear regression, adjusted for height, weight and sex. Vigorous PA showed the strongest association with femoral neck aBMD (β = 0.09, p b 0.001), while both moderate and vigorous PAs were associated with cor- tical area and trabecular vBMD in the weight-bearing tibia (all p b 0.05). Peak vertical accelerations were associated significantly with cortical area (β = 0.09, p b 0.001) and trabecular vBMD (β = 0.09, p = 0.001) of the tibia, whereas peak anterior–posterior accelerations showed no correlation with these properties. No positive association was found between objectively measured PA and bone parameters of the radius. In conclusion, vertical accelerations and moderate to vigorous PA independently predict bone properties, especially in the weight-bearing tibia, in 70-year-old men and women.
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