| 1. |
- Ebrahimzadeh, PR, et al.
(författare)
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A subpopulation analysis of f-MLP stimulated granulocytes migrating in filters
- 1996
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Ingår i: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 33:3, s. 231-250
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Tidskriftsartikel (refereegranskat)abstract
- Leukocyte migration in vitro has been studied extensively during many years without providing satisfactory theoretical models for the different migratory behaviors (chemotaxis and chemokinesis) of leukocyte populations. The present study utilized the fluid gradient chamber, which is a new method to study leukocyte migration in filters. Human neutrophils were applied between two stacked filters and migrated in all directions under the influence of constant concentrations or chemotactic gradients of f-MLP, maintained in fluid phase density gradients. The distributions of the granulocytes over filter depth were fitted to theoretical functions composed by 1-3 Gaussian distributions, representing subpopulations. The results showed that the neutrophils migrated as two discrete subpopulations during chemokinetic stimulation (a constant concentration of f-MLP). One of the subpopulations showed less active and passive (slow sedimentation under the influence of gravity) translocation. The most mobile subpopulation was divided into two new subpopulations when exposed to chemotactic stimulation (concentration gradient of f-MLP), one of which responded chemotactically and one of which migrated in random directions. The properties of the different subpopulations where characterized in terms of diffusion coefficient (random migration), convection velocity (chemotactic migration) and sedimentation coefficient (passive translocation).
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| 2. |
- Braide, M, et al.
(författare)
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Migration of human granulocytes in filters: effects of gravity and movable gradients of f-MLP
- 1994
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Ingår i: Biorheology. - THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB : PERGAMON-ELSEVIER SCIENCE LTD. - 0006-355X .- 1878-5034. ; 31:6, s. 617-630
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Tidskriftsartikel (refereegranskat)abstract
- The Boyden chamber technique for chemotaxis uses a mesh filter that constitutes a matrix for cell locomotion and, at the same time, creates a local restriction for convective fluid movements that allows the establishment of a diffusive concentration gradient of chemotactic substance in the filter. In the present study, the Boyden chamber was modified by the introduction of a filter sandwich that allowed cell migration both upwards and downwards and by the use of a fluid density gradient controlling cell buoyancy and mechanically supporting a movable chemotactic gradient. This method was used to study chemotaxis and random migration of human granulocytes under the influence of gravitational forces and movable gradients of f-MLP. The results show that gravity affected cell motion significantly during random migration but not during chemotaxis. The rate of chemotactic migration was dependent on the steepness of the spatio-temporal f-MLP gradients. A stationary spatial gradient produced less migration than a gradient that was slowly moved through the filter sandwich in a direction opposite to that of the cell migration. The presence of f-MLP at constant concentration caused a minor, statistically insignificant, increase of the rate of random migration.
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| 3. |
- Elo, Mika, et al.
(författare)
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Specific induction of heat shock protein 90beta by high hydrostatic pressure.
- 2003
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Ingår i: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 40:1-3, s. 141-146
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Tidskriftsartikel (refereegranskat)abstract
- In chondrocytes, a low-amplitude intermittent hydrostatic pressure induces production of extracellular matrix molecules, while high hydrostatic pressure inhibits it. High pressure increases cellular heat shock protein 70 level in a number of cell types on account of increased stabilisation of the heat shock protein 70 mRNA. In our experiments, only bovine primary chondrocytes, but not an immortalized chondrocytic cell line, could resist the induction of the stress response in the presence of continuous 30 MPa hydrostatic pressure. We have recently shown that protein synthesis is required for the stabilization. According to two-dimensional gel electrophoresis the synthesis of heat shock protein 90 was also increased in a chondrocytic cell line and in HeLa cells, and mass spectrometric analysis suggested that the induction was rather due to increase in heat shock protein 90beta than in heat shock protein 90alpha. The stress response was rather intense in HeLa cells, therefore, we investigated the effect of continuous 30 MPa hydrostatic pressure on the expression of the two heat shock protein 90 genes in HeLa cells using Northern and Western blot analyses. Heat shock protein 90beta mRNA level increased within 6 hours of exposure to 30 MPa hydrostatic pressure, while hsp90alpha level remained stable. At protein level there was a clear increase in the heat shock protein 90beta/heat shock protein 90alpha ratio, too. These results show a specific regulation of stress proteins in cells exposed to high hydrostatic pressure.
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| 4. |
- Kaarniranta, Kai, et al.
(författare)
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Stress responses of mammalian cells to high hydrostatic pressure.
- 2003
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Ingår i: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 40:1-3, s. 87-92
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Tidskriftsartikel (refereegranskat)abstract
- High hydrostatic pressure causes stress response in many types of mammalian cells. We have previously shown that an accumulation of heat shock protein 70 (Hsp70) in a chondrocytic cell line occurred without an activation of the gene itself. Stabilization of the hsp70 mRNA was shown to be the reason for the Hsp70 stress response in the pressurized cells. Since accumulation of Hsp70 in pressurized cells indicated that high hydrostatic pressure induces a stress response without heat shock transcription factor activation, we decided to investigate the activation of two other stress-associated transcription factors, activator protein-1 (AP-1) and nuclear factor-kappaB (NF-kappaB). Induction of Hsp70 in immortalized and primary chondrocytes, murine Neuro-2a neuroblastoma and HeLa cervical carcinoma cell lines was investigated at both mRNA and protein levels. In immortalized chondrocytes and HeLa cells, hsp70 mRNA levels were clearly elevated after 6 hours of the onset of 30 MPa continuous hydrostatic pressure, while in primary chondrocytes and Neuro-2a cells (the cells known to be stress-sensitive) no induction was observed. Surprisingly, neither heat shock nor high hydrostatic pressure could induce the hsp70 mRNA in Neuro-2a cells, although an activation of heat shock transcription factor could be observed in heat-shocked cells. No activation of the AP-1 and NF-kappaB binding to their target DNA sequences could be shown in the immortalized chondrocytes.
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| 5. |
- Karjalainen, Hannu, et al.
(författare)
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Gene expression profiles in chondrosarcoma cells subjected to cyclic stretching and hydrostatic pressure. A cDNA array study.
- 2003
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Ingår i: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 40:1-3, s. 93-100
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical forces have a profound effect on cartilage tissue and chondrocyte metabolism. Strenuous loading inhibits the cellular metabolism, while optimal level of loading at correct frequency raises an anabolic response in chondrocytes. In this study, we used Atlas Human Cancer cDNA array to investigate mRNA expression profiles in human chondrosarcoma cells stretched 8% for 6 hours at a frequency of 0.5 Hz. In addition, cultures were exposed to continuous and cyclic (0.5 Hz) 5 MPa hydrostatic pressure. Cyclic stretch had a more profound effect on the gene expression profiles than 5 MPa hydrostatic pressure. Several genes involved with the regulation of cell cycle were increased in stretched cells, as well as mRNAs for PDGF-B, glucose-1-phosphate uridylyltransferase, Tiam1, cdc37 homolog, Gem, integrin alpha6, and matrix metalloproteinase-3. Among down-regulated genes were plakoglobin, TGF-alpha, retinoic acid receptor-alpha and Wnt8b. A smaller number of changes was detected after pressure treatments. Plakoglobin was increased under cyclic and continuous 5 MPa hydrostatic pressure, while mitogen-activated protein kinase-9, proliferating cell nuclear antigen, Rad6, CD9 antigen, integrins alphaE and beta8, and vimentin were decreased. Cyclic and continuous pressurization induces a number of specific changes. In conclusion, a different set of genes were affected by three different types of mechanical stimuli applied on chondrosarcoma cells.
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| 6. |
- Kopakkala-Tani, Milla, et al.
(författare)
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Ultrasound stimulates proteoglycan synthesis in bovine primary chondrocytes.
- 2006
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Ingår i: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 43:3-4, s. 271-282
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical forces can stimulate the production of extracellular matrix molecules. We tested the efficacy of ultrasound to increase proteoglycan synthesis in bovine primary chondrocytes. The ultrasound-induced temperature rise was measured and its contribution to the synthesis was investigated using bare heat stimulus. Chondrocytes from five cellular isolations were exposed in triplicate to ultrasound (1 MHz, duty cycle 20%, pulse repetition frequency 1 kHz) at average intensity of 580 mW/cm2 for 10 minutes daily for 1-5 days. Temperature evolution was recorded during the sonication and corresponding temperature history was created using a controllable water bath. This exposure profile was used in 10-minute-long heat treatments of chondrocytes. Heat shock protein 70 (Hsp70) levels after one-time treatment to ultrasound and heat was analyzed by Western blotting, and proteoglycan synthesis was evaluated by 35S-sulfate incorporation. Ultrasound treatment did not induce Hsp70, while heat treatment caused a slight heat stress response. Proteoglycan synthesis was increased approximately 2-fold after 3-4 daily ultrasound stimulations, and remained at that level until day 5 in responsive cell isolates. However, chondrocytes from one donor cell isolation out of five remained non-responsive. Heat treatment alone did not increase proteoglycan synthesis. In conclusion, our study confirms that pulsed ultrasound stimulation can induce proteoglycan synthesis in chondrocytes.
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| 7. |
- Lammi, Mikko, 1961-
(författare)
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Current perspectives on cartilage and chondrocyte mechanobiology.
- 2004
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Ingår i: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 41:3-4, s. 593-596
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Forskningsöversikt (refereegranskat)abstract
- It is well known that physiological forces are essential for the maintenance of normal composition and structure of articular cartilage. Although some of the mechanisms of mechanotransduction are known today, there are certainly many others left unrevealed. In order to understand the complicated systems present in articular cartilage, we have to bring together the data from all fields of cartilage mechanobiology. The 3rd Symposium on Mechanobiology of Cartilage and Chondrocyte was a good effort towards that goal.
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| 8. |
- Lammi, Mikko, 1961-, et al.
(författare)
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Hydrostatic pressure-induced changes in cellular protein synthesis.
- 2004
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Ingår i: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 41:3-4, s. 309-313
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Forskningsöversikt (refereegranskat)abstract
- Hydrostatic pressure is a well-known effector of cellular protein synthesis. High continuous hydrostatic pressure inhibits protein synthesis in general. It has been known for a long time that 30S ribosomal subunit is associated with the effects of pressure on protein synthesis in prokaryotes, however, the mechanisms of action are still not completely understood. Our new data suggest that synthesis of eukaryotic elongation factor-2 (eEF-2) is decreased under 30 MPa continuous hydrostatic pressure. Thus, eEF-2 may have a role in the synthesis of pressure-regulated proteins in eukaryotic cells. The presence of pressure-sensitive proteins indicate that hydrostatic pressure can induce very specific responses in stressed cells. Accumulation of heat shock protein 70 and 90 beta occurs under high pressure, independent of the general inhibition of protein synthesis, although this response appears clearly weaker than during heat stress.
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| 9. |
- Larsson, Hans, et al.
(författare)
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Studies on blood pressure, pulse rate, laboratory parameters, blood and plams viscosity in 55 patients with impaired glucose tolerance (borderline diabetes)
- 1999
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Ingår i: Biorheology. - Amsterdam,The Netherlands : IOS Press. - 0006-355X .- 1878-5034. ; 36:1/2, s. 87-88
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Tidskriftsartikel (refereegranskat)abstract
- Abstract As a substudy to a broader investigation concerning clinical parameters in patients with impaired glucose tolerance blood and plasma viscosity were studied in 55 patients in ages from 39 to 81 years (mean age 62,4 years). These patients were selected from a large health study in southern Sweden where they presented with impaired glucose tolerance but without signs of vascular disease. At the time of our study these 55 patients were still not, 20 years after their first oral glucose tolerance test, classified as ouvert diabetes. Our intention was to study effects of minor disturbances of glucose tolerance on blood rheology. The patients had a laboratory profile close to that of patients with ouvert type 2 diabetes. Compared to a ontrol group of healthy individuals they had higher values for blood and plasma viscosity at all shear rates (p<0.001), higher values for b-glucose, ESR, triglycerides, s-GT (p<0.05-0.005) and lower values for s-creatinine p<0.001). It was also found that diastolic pressure, both at rest and after exercise, was positively correlated to plasma viscosity. This holds true also for systolic arm pressure. Pulse rate at rest and after exercise showed a negative correlation to blood rheology parameters. The pool of data is very large and further analyses are under way. So far our data show that even minor abnormalities of glucose metabolism are harmful and create a risk for vascular disease.
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| 10. |
- Leskinen, Jarkko, et al.
(författare)
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Genome-wide microarray analysis of MG-63 osteoblastic cells exposed to ultrasound.
- 2008
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Ingår i: Biorheology. - : IOS Press. - 0006-355X .- 1878-5034. ; 45:3-4, s. 345-354
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Tidskriftsartikel (refereegranskat)abstract
- It is well documented that low intensity pulsed ultrasound can be clinically used to accelerate bone fracture healing. Additionally, in vitro studies have shown that ultrasound can, for instance, increase mineralization, collagen production and alkaline phosphatase activity in osteoblasts. Despite the extensive research on the subject, the exact mechanism of ultrasound effect on bone cell gene regulation has not yet been deduced. In this study, we made an effort to reveal the features of genome-wide transcriptional response of osteoblast-type cells to ultrasound. MG-63 osteoblastic cell transcriptome was analyzed with whole genome microarray either 6 or 24 h after 30 min long exposure to 1.035 MHz pulsed ultrasound with three different acoustic pressures. Special attention was paid to the experimental design to minimize thermal effects and unwanted reflections of ultrasound. Microarray analysis suggested that ultrasound affects the genes involved with cellular membranes, and regulation of transcription as well. Several plasma membrane solute carriers were also regulated by ultrasound. It also changed the transcript level of several transcription factors belonging to the zinc finger proteins. However, ultrasound did not clearly promote genes involved with osteoblast differentiation.
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