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Biomedical subjects

Seppo Santavirta

Publications and source records attributed to Seppo Santavirta.

At least 19 recordsLinked to original sources
PubMed2007

Upregulation of matrix metalloproteinase (MMP)-1 and its activator MMP-3 of human osteoblast by uniaxial cyclic stimulation.

Proper mechanical loading is essential for bone remodeling and maintenance of human skeletal system. Matrix metalloproteinases (MMPs) are secreted by mesenchymal stromal lining cells and osteoblasts to prepare the initiation sites for osteoclastic bone resorption at the beginning of the remodeling cycle. However, only a few studies have addressed the effect of mechanical stress on MMPs and their endogenous tissue inhibitors of matrix metalloproteinases (TIMPs) in osteoblasts. In this study, the response of human osteoblasts to uniaxial cyclic stretching was investigated to clarify this more in detail. Stretching affected the orientation of the osteoblasts, and quantitative reverse transcription-polymerase chain reaction revealed coordinated upregulation of MMP-1 and its activator MMP-3 mRNA by cyclic 5% stretching at 3 h (p < 0.01). Upregulation of cyclooxygenase-2 mRNA was also found in response to cyclic 1 and 5% stretchings at 1, 3, and 6 h (p < 0.01). No changes were found in MMP-2, TIMP-1, and -2. The mRNA expression of MMP-9 was low and MMP-13 was not detected. This study suggests that MMP-1 and -3, enhanced by uniaxial cyclic mechanical stimulation of osteoblasts, are candidate key enzymes in the processing of collagen on bone surface, which might be necessary to allow osteoclastic recruitment leading to bone resorption. The strain might also play a role in cleaning of demineralized bone surface during the reversal phase, before bone formation starts.

Base Sequence↗
PubMed2006

Operative and nonoperative treatments of medial collateral ligament rupture with early anterior cruciate ligament reconstruction: a prospective randomized study.

BACKGROUND: The apparent consensus is that solitary medial collateral ligament rupture can be treated nonoperatively, but treatment of severe combined ruptures of the medial collateral ligament and anterior cruciate ligament remains controversial. HYPOTHESES: Nonoperative and early operative treatments of grade III medial collateral ligament rupture lead to similar results when the anterior cruciate ligament is reconstructed in the early phase. STUDY DESIGN: Randomized controlled clinical trial; Level of evidence, 1. METHODS: Forty-seven consecutive patients with combined anterior cruciate ligament and grade III medial collateral ligament injuries were randomized into 2 groups. The medial collateral ligament injury was treated operatively in group 1 (n = 23) and non-operatively in group 2 (n = 24). In both groups, the anterior cruciate ligament injury was treated with early reconstruction, using bone-patellar tendon-bone graft and interference screw. Two years postoperatively, knee stability was measured with a KT-1000 arthrometer and Telos valgus radiography and knee extension strength with a Biodex dynamometer and a 1-legged hop test. An International Knee Documentation Committee evaluation form and Lysholm score were completed. RESULTS: All 47 patients were available for clinical evaluation for a mean of 27 months (range, 20-37 months) after surgery. There were no statistically significant differences between the 2 groups with respect to subjective function of the knee, postoperative stability, range of motion, muscle power, return to activities, Lysholm score, and overall International Knee Documentation Committee evaluation. The subjective outcome and Lysholm score were good and anteroposterior knee stability excellent in both groups. CONCLUSION: Nonoperative and operative treatments of medial collateral ligament injuries lead to equally good results. Medial collateral ligament ruptures need not be treated operatively when the anterior cruciate ligament is reconstructed in the early phase.

Adult↗
PubMed2006

Immunohistochemical evaluation of inflammatory mediators in failing implants.

It was hypothesized that peri-implant tissue around loosening dental implants may contain cytokines with a potential to regulate osteoclasts. Peri-implant and/or gingival samples from loosened implants, chronic periodontitis (CP), and normal controls (n = 10 samples in each group) were analyzed using immunohistochemical staining to observe tumor necrosis factor alpha (TNF-alpha), interleukin 1-alpha (IL-1alpha), IL-6, platelet-derived growth factor A (PDGF-A), and transforming growth factor alpha (TGF-alpha). These cytokines were found in foreign-body giant cells, macrophages, fibroblasts, and epithelial cells. TNF-alpha, IL-1alpha, and IL-6 were increased (P < .05; unpaired t test) in peri-implantitis and CP, whereas PDGF-A and TGF-alpha were not. In conclusion, cytokines with a potential to activate osteoclasts were found in both peri-implantitis and CP, but the cytokine profiles differed in that IL-1alpha was the most prevalent cytokine in the former and TNF-alpha was the most common in the latter. These cytokines may contribute to peri-implant bone loss/loosening by stimulating formation and activity of osteoclasts and might be an amenable target for local therapies with cytokine modulators.

Adolescent↗
PubMed2005

Human osteoblasts produce cathepsin K.

Healthy bone is a rigid yet living tissue that undergoes continuous remodeling. Osteoclasts resorb bone in the remodeling cycle. They secrete H(+)-ions and proteinases to dissolve bone mineral and degrade organic bone matrix, respectively. One of the main collagenolytic proteinase in osteoclasts is cathepsin K, a member of papain family cysteine proteinases. Recently, it has been shown that osteoblasts may contribute to organic matrix remodeling. We therefore investigated their ability to produce cathepsin K for this action. Trabecular bone samples were collected from patients operated due to a fracture of the femoral neck. Part of the bone was decalcified and the rest was used for cell isolation. Sections from the decalcified bone were immunostained with antibodies against cathepsin K. Isolated cells were characterized for their ability to form mineralized matrix and subsequently analyzed for their cathepsin K production by Western blotting and quantitative RT-PCR. Osteoblasts, bone lining cells and some osteocytes in situ showed cathepsin K immunoreactivity and osteoblast-like cells in vitro produced cathepsin K mRNA and released both 42 kDa pro- and 27 kDa processed cathepsin K to culture media. Osteoblastic cathepsin K may thus contribute to collagenous matrix maintenance and recycling of improperly processed collagen I. Whether osteoblastic cathepsin K synthesis has consequences in diseases characterized by abnormal bone matrix turnover remains to be investigated.

Alkaline Phosphatase↗
PubMed2005

Pseudosynovial fluid from loosened total hip prosthesis induces osteoclast formation.

Interface tissue between the bone and loosening total hip implant is acidic and highly osteolytic. It is characterized by the formation of cathepsin K positive foreign body giant cells. Similar structures to those found in the normal joint surround the artificial hip joint. Cells in synovial membrane of the artificial hip generate synovial fluid that is called pseudosynovial fluid. Interface tissue fibroblasts are able to produce receptor activator of NF-kappaB ligand (RANKL), which can induce osteoclastogenesis during the loosening process. Western blot analysis indicated that RANKL is present in the pseudosynovial fluid. Pseudosynovial fluid induced cultured peripheral blood mononuclear cells to form multinuclear TRAP positive giant cells. In the presence of osteoprotegerin, the soluble RANKL decoy receptor, the number of TRAP positive multinuclear cells was reduced to half (p < 0.05). The multinuclear cells induced with pseudosynovial fluid contained active cathepsin K protein and were capable of bone matrix resorption in vitro. The cells were shown to express osteoclast phenotype markers, such as mRNA for cathepsin K, TRAP, and calcitonin receptor. It is therefore apparent that pseudosynovial fluid from patients with aseptic loosening of total hip prosthesis contains a potent osteoclastogenic factor RANKL that further suggests a favorable environment for osteoclast formation in the peri-implant tissues. It is thus concluded that suppression of RANKL activity may be beneficial in terms of increasing the lifetime of total hip prostheses.

Acid Phosphatase↗
PubMed2005

Biotribology.

Explore the source record for details and available documents.

Arthroplasty, Replacement, Hip↗
PubMed2005

The microenvironment around total hip replacement prostheses.

The metal stem of the totally replaced hip carries load and resists fatigue, but it is electrochemically corroded. Metallic atoms act as haptens, induce type 1 T-helper cells/Th1-type immune responses and enhance periprosthetic osteolysis. Stiff metal implants, which do not have the same elasticity as the surrounding bone, cause stress shielding. Cyclic loading and lack of ligamentous support lead to mechanical and ischemia reperfusion injury and particle formation from bone, polymethylmethacrylate, and porous implant surfaces, which accelerate third-body polyethylene wear. Surgical injury and micromotion induce the formation of a fibrous capsule interface. Type-B lining cells produce lubricin and surface-active phospholipids to promote solid-to-solid lubrication but may loosen the implant from bone. The pumping action of the cyclically loaded joint and synovial fluid pressure waves dissect the implant-host interface and transports polyethylene particles and pro-inflammatory mediators to the interface. Hyaluronan induces formation of a synovial lining like layer. Because of its localization close to bone, foreign body inflammation at the interface stimulates osteoclastogenesis and peri-implant bone loss. Metal-on-metal and ceramic-on-ceramic pairs might minimize third body wear, but can lead to high-impact load of the acetabulum. Diamond coating of a metal-on-polyethylene couple might solve both of these problems. The basic biomaterial solutions allow good mechanical performance and relatively long life in-service, but surface modifications (porous coating, hydroxyapatite, diamond, bioglass, and others) may facilitate performance of the implant and improve the biomaterial and body interfaces.

Arthroplasty, Replacement, Hip↗
PubMed2005

Interface tissue fibroblasts from loose total hip replacement prosthesis produce receptor activator of nuclear factor-kappaB ligand, osteoprotegerin, and cathepsin K.

OBJECTIVE: The highly osteolytic interface tissue between the bone and loosening total hip prosthesis is characterized by low pH, formation of foreign body giant cells, osteoclasts, and production of receptor activator of nuclear factor-kappaB (RANKL) and cathepsin K. We hypothesized that fibroblasts in the interface tissue may form a source for RANKL production. METHODS: Primary interface tissue fibroblasts, fibrous joint capsule fibroblasts, and trabecular bone osteoblasts were stimulated with tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta), IL-6, IL-11, or 1alpha,25-(OH)2 vitamin D3. Cellular RANKL and released cathepsin K were detected by Western blotting. RANKL in cell lysates and osteoprotegerin (OPG) in cell culture medium were measured by ELISA. RANKL, OPG, and cathepsin K mRNA were measured with quantitative reverse transcriptase polymerase chain reaction. RESULTS: Interface tissue fibroblasts were found to produce RANKL. 1alpha,25-(OH)2 vitamin D3 stimulation increased RANKL mRNA expression. TNF-alpha was found to be the most potent OPG inducer in interface tissue fibroblasts. Cathepsin K mRNA production in fibroblasts was upregulated roughly 3-fold (p < 0.01) after 1alpha,25-(OH)2D3 stimulation, and both pro- and active cathepsin K protein was released to fibroblast culture media. CONCLUSION: Interface tissue fibroblasts are able to produce RANKL, OPG, and cathepsin K and may contribute indirectly and directly to pathologic periprosthetic collagenolysis and bone destruction.

Aged↗
PubMed2005

Increased expression and processing of ADAM 12 (meltrin-alpha) in osteolysis associated with aseptic loosening of total hip replacement implants.

OBJECTIVE: To assess the expression and processing of a disintegrin and metalloproteinase, ADAM 12 (meltrin-alpha), in the formation of multinuclear cells. Methods. In situ hybridization, immunohistochemical staining, and Western blotting of interface membrane around loosened total hip replacement implants. Macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor-kappaB ligand (RANKL) costimulation of human monocytes followed by FACS, immunofluorescence staining, Western blotting, and bone resorption assay. RESULTS: ADAM 12 mRNA-containing mononuclear cells were often seen in a close spatial relationship with ADAM 12-positive multinuclear cells. Morphometric analysis of ADAM 12 disclosed that 53% +/- 2% of all interface cells were ADAM 12-positive compared to 5% +/- 1% in controls (p < 0.001). M-CSF and RANKL were richly present in interface tissue around loosening implants. Upon M-CSF and RANKL costimulation of human monocytes in vitro, the ADAM 12 staining pattern changed over time, and ADAM 12-positive cells formed large mono-, bi-, and multinuclear cells at Day 7 and many multinuclear giant cells and/or osteoclasts at Day 14. Western blot disclosed 90 kDa latent ADAM 12L but also the metalloproteinase-cleaved, fusion-active 60 kDa form transiently just before the burst of fusion. CONCLUSION: ADAM 12, well recognized for participation in cell-cell fusion in myoblast formation, is upregulated and processed upon formation of multinuclear giant cells and osteoclasts. It may play a role in formation of giant cells and osteoclasts around loosened total hip replacement implants.

ADAM Proteins↗
PubMed2004

Fracture dislocations of the cervical spine: a review of 106 conservatively and operatively treated patients.

We compared clinical outcomes following conservative treatment of subaxial fracture dislocations of the cervical spine and posterior fusion using bone grafts and interspinous Roger's wiring (Bohlman modification). We reviewed 106 patients: 51 were treated primarily surgically, and 55 treated conservatively served as historical controls. Those patients who neurologically recovered at least one Frankel grade had on average less displacement on discharge (1.3 mm vs 3.1 mm, p=0.04). Although anatomical outcomes were better in the operatively treated group (1.6 mm vs 2.9 mm displacement at end of follow-up, p=0.001), there was no difference in neurological recovery. Late neck pain correlated with residual displacement ( p=0.04) and was more common in the conservatively treated patients ( p=0.01). Time in hospital was shorter in the group with posterior fusions, and complication rates were similar to those found after conservative treatment. A significant number of the conservatively treated patients developed kyphotic deformity, and 29% needed later surgery because of chronic instability or unacceptable anatomical results.

Adolescent↗
PubMed2004

Arthroscopic operations in joint tuberculosis.

We assessed the usefulness of arthroscopy in bone and joint tuberculosis (11 knees, 1 elbow and 1 ankle). In all 11 patients with knee joint involvement the arthroscopic operation were successful with a significant improvement in the range of motion (P=0.007) and knee score (P=0.003). There were no cases of reactivation or recurrence during a follow-up period of 15-42 months. In contrast, in the two patients with ankle or elbow joint involvement and bone destruction, arthroscopy had to be converted to open operation. Minor trauma, a short hospitalization time and a short post-operative rehabilitation period combined with good cosmetic and clinical results favor the use of the arthroscopic technology in the surgical treatment of tuberculous arthritis of the knee.

Adolescent↗
PubMed2004

Bioabsorbable fixation devices in trauma and bone surgery: current clinical standing.

Bioabsorbable fixation devices are increasingly used in trauma, orthopedic and craniomaxillofacial surgery. The devices are essentially made of polylactic acid and/or polyglycolic acid polymers. Ultra-high-strength implants are manufactured from such polymers using self-reinforcing techniques. Implants are available for stabilization of fractures, osteotomies, bone grafts and fusions, as well as for reattachment of ligaments, tendons, meniscal tears and other soft tissue structures. As these implants are completely absorbed, the need for a removal operation is overcome and long-term interference with tendons, nerves and the growing skeleton is avoided. The risk of implant-associated stress shielding, peri-implant osteoporosis and infections is reduced. Implants do not interfere with clinical imaging. Current clinical use of bioabsorbable devices is reviewed.

Absorbable Implants↗
PubMed2004

Hyaluronate inhibits the interleukin-1beta-induced expression of matrix metalloproteinase (MMP)-1 and MMP-3 in human synovial cells.

Intra-articular administration of hyaluronate (HA) is an effective treatment for arthritis. HA injections can decrease not only joint pain but also synovial effusion, although little is known concerning the mechanism of HA action. The aim of this study was to investigate the role of HA on the expression and production of matrix metalloproteinase (MMP) in synovial cells activated by interleukin (IL)-1beta in order to achieve a better understanding of exogenous HA function in the extracellular matrix degradation in arthritic joints. Human synovial cells were incubated with HA (0.1-1000 microg/ml) and/or IL-1beta (1 ng/ml). The expression of MMP-1 and MMP-3 mRNAs was analyzed by quantitative real-time polymerase chain reaction. The protein levels of MMP-1 and MMP-3 in cultured media were measured by immunoblotting. Expression of MMP-1 and MMP-3 mRNAs was induced by IL-1beta. The IL-1beta-mediated induction of MMP-1 mRNA expression was attenuated by 10 microg/ml HA (p=0.026) and that of MMP-3 mRNA was strongly down-regulated in the presence of 10 or 1000 microg/ml HA (p<0.001). The increased protein levels of MMP-1 and MMP-3 were also reduced by 1000 microg/ml HA. These data suggest that HA inhibits the expression and production of MMP-1 and MMP-3 in IL-1beta-stimulated human synovial cells. We therefore prepose that intra-articular HA may rescue inflamed joints from bone and cartilage destruction by reducing the production of MMP-1 and MMP-3.

Cells, Cultured↗
PubMed2004

Use of polymerase chain reaction to diagnose tuberculous arthritis from joint tissues and synovial fluid.

CONTEXT: Tuberculosis of the joints and bones is a significant worldwide problem, often leading to joint and bone destruction. The diagnosis of this disease manifestation is difficult. OBJECTIVE: To assess the role of conventional diagnostics compared to polymerase chain reaction applied to samples obtained at arthroscopy. DESIGN: This was an open observational study that was blinded to the microbiologist, histopathologist, and molecular biologist responsible for assessing the main outcome measures. PATIENTS: Seven patients (8 samples) with joint and bone tuberculosis and 14 patients (16 samples) with nontuberculous joint and bone disease. INTERVENTION: Arthroscopic examination and tissue sample collection. MAIN OUTCOME MEASURES: Mycobacterium tuberculosis staining, culture, and histopathologic assessment of caseating granulomas vs polymerase chain reaction. RESULTS: Polymerase chain reaction was positive in all cases of true tuberculosis and falsely identified 2 samples as positive, both however, in patients who had lung tuberculosis in the past. CONCLUSIONS: Conventional bacteriological methods for demonstration of M tuberculosis are not very sensitive and can be time-consuming. Polymerase chain reaction of arthroscopically obtained joint tissue biopsies appears promising in the early diagnosis of tuberculous arthritis.

Arthritis, Infectious↗