| 1. |
- Brändström, Helena, et al.
(författare)
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Regulation of osteoprotegerin mRNA levels by prostaglandin E2 in human bone marrow stroma cells.
- 1998
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Ingår i: Biochemical and biophysical research communications. - : Elsevier BV. - 0006-291X. ; 247:2, s. 338-41
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Tidskriftsartikel (refereegranskat)abstract
- The recently cloned osteoclastogenesis inhibitory factor, or osteoprotegerin (OPG), has been shown to be a potent inhibitor of osteoclast formation. The inhibition is believed to be mediated through specific binding of OPG to a cell surface ligand on osteoblastic stromal cells. In this report we have studied the effect of the bone resorbing agent prostaglandin E2 (PGE2) on OPG mRNA levels in primary cultures of human bone marrow stroma cells (hBMSC). PGE2 dose- and time-dependently down-regulated the mRNA levels of OPG, as measured by RNAse protection assay. After 4 hours of stimulation with 1 microM PGE2, OPG mRNA levels were significantly decreased. The inhibitory effect was seen at and above 1 nM of PGE2. To elucidate whether the OPG mRNA levels are regulated via the proteinkinase A and/or the proteinkinase C pathways we stimulated cells with either forskolin (FSK) or phorbolic ester (PDbu) respectively. FSK (10 microM) decreased OPG mRNA levels to 50 % of control, whereas PE (10 nM) upregulated the mRNA levels to 250 % of control. These data show that PGE2 down-regulates the expression of OPG mRNA in hBMSC, probably via an increase in cAMP. This mechanism might be involved in PGE2-induced bone resorption.
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| 2. |
- Brändström, Helena, et al.
(författare)
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Tumor necrosis factor-alpha and -beta upregulate the levels of osteoprotegerin mRNA in human osteosarcoma MG-63 cells.
- 1998
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Ingår i: Biochemical and biophysical research communications. - : Elsevier BV. - 0006-291X. ; 248:3, s. 454-7
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Tidskriftsartikel (refereegranskat)abstract
- Osteoprotegerin (OPG) is a recently cloned soluble member of the tumor necrosis factor receptor family. OPG has been shown to inhibit osteoclast recruitment by binding to OPG-ligand, an osteoclast differentiating factor on osteoblastic stromal cells, thereby blocking osteoclastogenesis. In this report we have examined the effect of tumor necrosis factor-alpha (TNF-alpha) and tumor necrosis factor-beta (TNF-beta) on OPG mRNA levels in the human osteosarcoma cell line MG-63. We demonstrate that both TNF-alpha and TNF-beta dose- and time-dependently upregulate the mRNA levels of OPG. The effect is significant at and above 5 pM of TNF-alpha and 1 pM of TNF-beta. The stimulatory effect on OPG mRNA levels in MG-63 cells was detected after 2 hrs of incubation with TNF-alpha or TNF-beta. These data demonstrate that the expression of OPG in osteoblasts, with subsequent effects on osteoclastogenesis, is regulated by TNFs.
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| 3. |
- Frost, Anders, et al.
(författare)
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Interleukin-13 inhibits cell proliferation and stimulates interleukin-6 formation in isolated human osteoblasts.
- 1998
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Ingår i: The Journal of clinical endocrinology and metabolism. - 0021-972X. ; 83:9, s. 3285-9
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Tidskriftsartikel (refereegranskat)abstract
- Interleukin-13 (IL-13) is a recently identified cytokine that is secreted by activated T cells and regulates inflammatory responses. We have investigated the effects of IL-13 on isolated human osteoblast-like cells (hOB). IL-13 dose-dependently (1-100 pmol/L) reduced the incorporation rate of [3H]thymidine in hOB cells by more than 50%. Using a cell metabolic assay as well as direct cell counting, we found that treatment with IL-13 lead to a decrease in hOB cell number. The effect was both time and dose dependent, and after 12 days of culture, treatment with IL-13 (0.1 nmol/L) caused a 70% decrease in the number of cells. Also, IL-13 increased the levels of IL-6 messenger ribonucleic acid in hOBs, as measured by ribonuclease protection assay, and stimulated secretion of IL-6 into culture supernatants. In conclusion, IL-13 inhibits cell proliferation and increases IL-6 formation in human osteoblasts. Our findings suggest that IL-13 may cause bone loss due to impaired osteoblastic growth and IL-6-induced osteoclast recruitment.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Jonsson, Bert, 1961-, et al.
(författare)
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Predictive head movements in 6-month old infants
- 1998
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Ingår i: Infant Behavior and Development. - : Elsevier. - 0163-6383 .- 1879-0453. ; 21:Supplement, s. 491-491
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate infant’s predictive head-tracking relatively to a linearly moving object. Object’s motion was produced by a large computer controlled plotter, tilted 15 degrees forward from vertical position. The objects moved on a white ainted aluminum sheet (98x 130 cm). Objects were presented in three different conditions. It was either visible all the time, occluded during part of its motion, or the room lights were extinguished during part of the object’s motion. Infant’s head movements were recorded by two infrared cameras and mixed onto a single video screen. Each infant was shown 6 initial and 6 final visible trials, and 6 times 2 occlusion trials in between, occlusion either by occluder or extinguished light. Sticky paper was placed on the infant’s head and by a touch-screen technology the markers were coded every 100 msec.
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| 8. |
- Munakata, Yuko, et al.
(författare)
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When it helps to occlude and obscure : 6-month-olds' predictive tracking of moving toys
- 1996
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Ingår i: Infant Behavior and Development. - 0163-6383 .- 1879-0453. ; 19:Suppl. 1, s. 639-639
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Tidskriftsartikel (refereegranskat)abstract
- What do infants know about hidden objects’? Previous research suggests that the answer depends on how the objects are hidden. For instance, infants appear to reach for toys in the dark (Clifton, Rochat, Litovsky, & Penis, 1991; Hood & Willatts, 1986) before they reach for toys occluded in the light. However, these experiments have not compared directly toys occluded in the light and by darkness. The current experiment tests infants under both conditions in the same paradigm. In addition, the experiment introduces a combined ccluderdarkness condition to test two distinct explanations for a possible advantage in the dark. First, infants may have knowledge about hidden objects but cannot act on it for occluder-specific reasons (e.g., means-ends deficits, beliefs about the whether the object is accessible). Second, infants may have graded representations of occluded objects that can be more easily maintained in the face of global darkness than with the direct visual interference of an occluder. Counterintuitive results from the current experiment provide evidence for both representational and occluder-specific effects.
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| 9. |
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| 10. |
- Savelsbergh, Geert, et al.
(författare)
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The coupling of head, reach and grasp movement in ninemonths old infant prehension
- 1997
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Ingår i: Scandinavian Journal of Psychology. - Wiley : Wiley. - 0036-5564 .- 1467-9450. ; 38:4, s. 325-333
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Tidskriftsartikel (refereegranskat)abstract
- In 9-month-old-infants adjustments in the reaching pattern to sudden changes in object location were examined. An attractive ball was presented to the infants at their midline and on some trials (perturbation trials) the ball suddenly changed position 15 cm to the right or left during the reach. For the perturbed trials the movement times approximately doubled compared to the control trials and significantly fewer balls were grasped. The results indicate that infants need to finish the first movement before being able to redirect the reach to a new destination. The correlation between the latency of the head and hand adjustment to the perturbation were 0.85 and 0.78 for movements to the left and to the right, respectively, indicating a tight coupling. The time between the start of the perturbation and peak velocity(TPPV) was significantly shorter for the head movement than for the hand movement, indicating that the head is leading the hand.
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