Effects of arginine-vasopressin and parathyroid hormone-related protein (1-34) on cell proliferation and production of YKL-40 in cultured chondrocytes from patients with rheumatoid arthritis and osteoarthritis

OBJECTIVE

Both arg-vasopressin (AVP) and parathyroid hormone-related protein (PTHrP) may act as proinflammatory hormones. In addition, they have been suggested to be involved in the pathophysiology of rheumatoid arthritis (RA). We therefore investigated the effects of AVP and PTHrP (1-34) on cell proliferation and secretion of the glycoprotein YKL-40 in human chondrocytes derived from healthy subjects as well as from patients with RA or osteoarthritis (OA).

METHOD

Primary cultures of human chondrocytes were incubated with AVP (1-100 pmol/l) or PTHrP (1-34) (0.1-100 nmol/l). Cell proliferation was measured as [3H]thymidine incorporation. Intracellular cAMP and YKL-40 in cell medium were determined by commercially available kits.

RESULTS

AVP and PTHrP (1-34) increased proliferation in chondrocytes derived from healthy donors as well as from RA and OA patients. PTHrP (1-34), but not AVP, increased intracellular levels of cAMP. PTHrP (1-34) did not change the amount of YKL-40 in chondrocytes from healthy subjects or patients with OA. AVP tended to decrease the secretion of YKL-40 from healthy chondrocytes. Both PTHrP (1-34) and AVP increased YKL-40 secretion from RA chondrocytes. In contrast, AVP decreased the secretion of YKL-40 in chondrocytes from patients with OA.

CONCLUSION

AVP and PTHrP (1-34) stimulated proliferation in human chondrocytes derived from healthy subjects as well as from patients with RA or OA. However, the effects of AVP and PTHrP (1-34) on YKL-40 secretion varied depending on the origin of the chondrocytes.

Radial head prosthesis after fracture of radial head with associated elbow instability

INTRODUCTION

Fractures of the radial head and associated elbow instability can be treated with operation with radial head prosthesis. In this study, we evaluate function 1-7 years after implantation and also function after removal of five prostheses.

MATERIAL AND METHODS

Eighteen patients with radial head fracture and associated elbow instability were evaluated 3.7 years (1-7) after implantation of a radial head prosthesis. Pain at rest and during activity was measured with a visual analogue scale (VAS). Test of stability and neurological examination was done manually as well as measurement of the range of motion, using a goniometer. Activity of daily living (ADL) was estimated using five questions where the answers were graded between 1 and 3. The patients were asked to grade their general satisfaction according to the following scale; very satisfied, satisfied, not satisfied, disappointed. Plain X-rays were taken and 14 patients agreed to have their elbow strength evaluated using the validated BTE work simulator.

RESULTS

Five prostheses had been extracted due to poor range of motion. All these patients improved after extraction. All elbows were stable. No patient with extracted prosthesis had VAS score >2. The mean extension defect for this group was 15 degrees (5-25) compared to the mean extension defect for the 13 patients with the prosthesis still in place 15 degrees (0-40). The highest VAS score for the patients with prosthesis was five but the mean as low as 0.8. In the whole group, 13 patients were pain free. ADL function was good in general. The X-rays of the prostheses, still in place, showed radiolucent lines in 7 of the 13 patients. In the whole group, there was a significant decrease in supination, flexion and extension strength (P<0.01, P<0.01, P<0.05).

DISCUSSION

Radial head prosthesis works as a spacer after fracture of the radial head and associated instability. If range of motion is much restricted post-operatively, the prosthesis can be removed with improved function as result.

Fusion of radiostereometric analysis data into computed tomography space: application to the elbow joint

Improvement of joint prostheses is dependent upon information concerning the biomechanical properties of the joint. Radiostereometric analysis (RSA) and electromagnetic techniques have been applied in previous cadaver and in vivo studies on the elbow joint to provide valuable information concerning joint motion axes. However, such information is limited to mathematically calculated positions of the axes according to an orthogonal coordinate system and is difficult to relate to individual skeletal anatomy. The aim of this study was to evaluate the in vivo application of a new fusion method to provide three-dimensional (3D) visualization of flexion axes according to bony landmarks. In vivo RSA data of the elbow joint's flexion axes was combined with data obtained by 3D computed tomography (CT). Results were obtained from five healthy subjects after one was excluded due to an instable RSA marker. The median error between imported and transformed RSA marker coordinates and those obtained in the CT volume was 0.22 mm. Median maximal rotation error after transformation of the rigid RSA body to the CT volume was 0.003 degrees . Points of interception with a plane calculated in the RSA orthogonal coordinate system were imported into the CT volume, facilitating the 3D visualization of the flexion axes. This study demonstrates a successful fusion of RSA and CT data, without significant loss of RSA accuracy. The method could be used for relating individual motion axes to a 3D representation of relevant joint anatomy, thus providing important information for clinical applications such as the development of joint prostheses.

Variability in synovial inflammation in rheumatoid arthritis investigated by microarray technology

In recent years microarray technology has been used increasingly to acquire knowledge about the pathogenic processes involved in rheumatoid arthritis. The present study investigated variations in gene expression in synovial tissues within and between patients with rheumatoid arthritis. This was done by applying microarray technology on multiple synovial biopsies obtained from the same knee joints. In this way the relative levels of intra-patient and inter-patient variation could be assessed. The biopsies were obtained from 13 different patients: 7 by orthopedic surgery and 6 by rheumatic arthroscopy. The data show that levels of heterogeneity varied substantially between the biopsies, because the number of genes found to be differentially expressed between pairs of biopsies from the same knee ranged from 6 to 2,133. Both arthroscopic and orthopedic biopsies were examined, allowing us to compare the two sampling methods. We found that the average number of differentially expressed genes between biopsies from the same patient was about three times larger in orthopedic than in arthroscopic biopsies. Using a parallel analysis of the tissues by immunohistochemistry, we also identified orthopedic biopsies that were unsuitable for gene expression analysis of synovial inflammation due to sampling of non-inflamed parts of the tissue. Removing these biopsies reduced the average number of differentially expressed genes between the orthopedic biopsies from 455 to 171, in comparison with 143 for the arthroscopic biopsies. Hierarchical clustering analysis showed that the remaining orthopedic and arthroscopic biopsies had gene expression signatures that were unique for each patient, apparently reflecting patient variation rather than tissue heterogeneity. Subsets of genes found to vary between biopsies were investigated for overrepresentation of biological processes by using gene ontology. This revealed representative 'themes' likely to vary between synovial biopsies affected by inflammatory disease.

Laser-induced fluorescence measurement of the ion-energy-distribution function in a collisionless reconnection experiment

Observations in space and laboratory plasmas suggest magnetic reconnection as a mechanism for ion heating and formation of non-Maxwellian ion velocity distribution functions (IVDF). Laser-induced fluorescence measurements of the IVDF parallel to the X line of a periodically driven reconnection experiment are presented. A time-resolved analysis yields the evolution of the IVDF within a reconnection cycle. It is shown that reconnection causes a strong increase of the ion temperature, where the strongest increase is found at the maximum reconnection rate. Monte Carlo simulations demonstrate that ion heating is a consequence of the in-plane electric field that forms around the X line in response to reconnection.

Treadmill training and body weight support for walking after stroke

BACKGROUND

Treadmill training, with or without some body weight supported using a harness, is a method of treating walking after stroke. A systematic review is required to assess the cost, effectiveness, and acceptability of this treatment.

OBJECTIVES

To assess the effectiveness of treadmill training and body weight support, individually or in combination, in the treatment of walking after stroke. The primary outcomes investigated were walking speed, endurance and dependency.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched 2 March 2005), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2004), MEDLINE (1966 to January 2005), EMBASE (1980 to February 2005), CINAHL (1982 to February 2005) and PEDro (last searched 2 March 2005). In addition, we handsearched relevant conference proceedings, screened reference lists and contacted trialists to identify further published and unpublished trials.

SELECTION CRITERIA

Randomised or quasi-randomised controlled and cross-over trials of treadmill training and body weight support, individually or in combination, for the treatment of walking after stroke were eligible.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, extracted data, and assessed quality. We contacted trialists for additional information. We used a fixed-effect model for analysis, but if heterogeneity existed a random-effects model was used. We analysed the results as weighted mean differences (WMD) for continuous variables and relative risk (RR) for dichotomous variables.

MAIN RESULTS

Fifteen trials (622 participants) were included. There were no statistically significant differences between treadmill training, with or without body weight support, and other interventions for walking speed or dependence. Among participants who could walk independently at the start of treatment, treadmill training with body weight support tended to produce higher walking speeds (WMD 0.09 m/s, 95% confidence interval (CI) -0.02 to 0.20 for speed; fixed-effect), but this result was not statistically significant. An individual trial tended to support the use of treadmill training with body weight support for dependent walkers as compared to treadmill training alone. One of three individual trials indicated that independent walkers may benefit from treadmill training combined with other task-orientated exercise. However, data are very limited. Adverse events occurred more frequently in participants receiving treadmill training but these were not judged to be clinically serious events.

AUTHORS' CONCLUSIONS

Overall no statistically significant effect of treadmill training with or without body weight support was detected. Although individual studies suggested that treadmill training with body weight support may be more effective than treadmill training alone and that treadmill training plus task-oriented exercise may be more effective than sham exercises, further trials are required to confirm these findings.

Orthopaedic surgery of the lower limbs in 49,802 rheumatoid arthritis patients: results from the Swedish National Inpatient Registry during 1987 to 2001

OBJECTIVES

To analyse changes in the rates of hospital admission and use of orthopaedic surgery to the lower limbs in Swedish patients with rheumatoid arthritis between 1987 and 2001.

METHODS

Data for all rheumatoid patients admitted to hospital between 1987 and 2001 were abstracted from the Swedish National Hospital Discharge Register (SNHDR). The data in the register are collected prospectively, recording all inpatient admissions throughout Sweden. The SNHDR uses the codes for diagnoses at discharge and surgical procedures according to the Swedish version of the International Classification of Diseases (ICD).

RESULTS

In all, 49,802 individual patients with rheumatoid arthritis were identified, accounting for 159,888 inpatient visits. Hospital admissions for rheumatoid arthritis decreased by 42% (p<0.001) during the period 1987 to 2001. Twelve per cent of all admissions were for a rheumatoid arthritis related surgical procedure to the lower limbs; those admissions decreased markedly (by 16%) between 1987 and 1996, and by 12% between 1997 and 2001, as did the overall number of rheumatoid arthritis related surgical procedures to the lower limbs during both time periods. Between 1997 and 2001, 47% of all rheumatoid arthritis related surgical procedures were total joint arthroplasties. There was an overall trend towards reduced length of hospital stay after orthopaedic surgery to the lower limbs during the study period.

CONCLUSIONS

Rates of hospital admission and rheumatoid arthritis related surgical procedures to the lower limbs in Swedish patients with rheumatoid arthritis decreased between 1987 and 2001. This may reflect trends in disease severity, management, and health outcomes of this disease in Sweden.

Morphological Characterization of Receptor Activator of NFkappaB Ligand (RANKL) and IL-1beta Expression in Rodent Collagen-Induced Arthritis

Bone loss represents a major unsolved problem in rheumatoid arthritis (RA). The receptor activator of nuclear factor-kappaB ligand (RANKL) is essential for the development and activation of osteoclasts, which are key mediators of bone erosions. This study was performed to determine temporal and spatial expression of RANKL compared with the potentially destructive cytokine interleukin-1beta (IL-1beta), related to progression of synovitis and joint destruction in collagen-induced arthritis (CIA), a model of RA. CIA was induced in dark agouti (DA) rats, and tissue specimens were obtained for immunohistochemical analyses at various time points before and after disease onset. Arthritis was monitored visually, and joint pathology was examined histologically. No disease-preceding expression of RANKL was detected. However, a marked increase of both RANKL- and IL-1beta-expressing cells correlated with the progression of synovial inflammation and clinical disease severity. Abundant and concomitant expression of these cytokines was detected at sites of bone erosion, where a colocalization by osteoclast-like multinuclear tartrate-resistant acid phosphatase (TRAP)+ cells was noted. In contrast to the paucity of RANKL expression in cartilage, an abundant expression of IL-1beta was demonstrated, particularly in superficial cartilage layers. These data support the hypothesis that RANKL and IL-1beta are central contributors to joint destruction in CIA.

Low IGF-I in synovial fluid and serum in patients with aseptic prosthesis loosening

BACKGROUND

We have previously shown that proliferation in primary cultures of human osteoblast-like cells is lower after exposure to synovial fluid from patients with aseptic prosthesis loosening than after exposure to synovial fluid from patients with osteoarthrosis.

MATERIALS AND METHODS

Insulin-like growth factors (IGF) I and II and IGF binding proteins (IGFBP) 3-6, were measured with radioimmunoassy in synovial fluid and in serum from patients with aseptic prosthesis loosening or osteoarthrosis. Proliferation in osteoblast-like MG-63 cells was studied with the CyQUANT assay.

RESULTS

IGF-I and IGFBP-4 concentrations were lower whereas the concentration of IGFBP-6 was higher in synovial fluids from patients with prosthesis loosening than in synovial fluid from patients with osteoarthrosis. IGF-I concentrations in serum from patients with prosthesis loosening were also lower than in the osteoarthrosis group, and were even below the normal range in most cases (72%). Synovial fluid from patients with aseptic loosening had a weaker stimulatory effect on MG63 osteoblast-like cell proliferation than synovial fluid from patients with osteoarthrosis, but there was no difference between the two groups when a human IGF-I antibody was added.

INTERPRETATION

Low levels of IGF-I in synovial fluid possibly result from low serum levels and may be a mechanism leading to aseptic prosthesis loosening.

Standard orientation of the pelvis: validation on a model and ten patients

PURPOSE

To validate an image post-processing method for re-orienting the pelvis in CT volumes to a standardized orientation in a model and in 10 patients.

MATERIAL AND METHODS

Twenty-four CT volumes of a pelvic model and 10 pairs of postoperative total hip arthroplasty (THA) patient CT scans were rotated to a defined pelvic standard orientation and the rotation was recorded. For precision, a test-retest procedure was used. For accuracy, three exactly represented coordinate points were used. For clinical application, the standard orientation was used for calculating the direction of acetabular cup migration from a previous model study.

RESULTS

Precision of pelvic standard orientation, calculated as maximal directional error, was better than 1 degrees in the model study and better than 1.5 degrees in the patient study. Accuracy, expressed as angle between ideal and measured coordinate axes, was 0.1 degrees for x, y, z axes. No measurable systematic errors were found. When applied to acetabular cup migration in the model, standardization of pelvic orientation had no significant effect on the measurements.

CONCLUSION

Reorienting the pelvis during image post-processing was shown to be accurate. It enables measurements relative to the pelvis and minimizes the dependency of patient positioning.

Periacetabular osteotomy. Good pain relief in symptomatic hip dysplasia, 32 patients followed for 4 years

BACKGROUND

When surgical treatment of dysplastic hip osteoarthrosis is necessary, osteotomy is preferable to fusion or THR. We evaluated periacetabular osteotomy as a method of choice.

PATIENTS AND METHODS

We treated 36 symptomatic dysplastic hip joints (32 patients) with the Bernese periacetabular osteotomy (PAO) between 1994 and 2001. We used the ilio-inguinal (I-I) approach in 32 hips and a modified Smith-Petersen (S-P) approach in 4. The patients were followed for mean 4 (1.5-8) years. In 1 patient with coxa valga, a varus femoral osteotomy was performed 1 year after PAO. 2 hips, in which we used the modified S-P approach, necessitated a capsulotomy.

RESULTS

The median Merle d'Aubignè score increased from 13 points preoperatively to 16 points postoperatively. This improvement in terms of pain, motion and ambulation was accompanied by spatial reorientation and correction. The lateral center edge angle of Wiberg (CE) improved from an average of 7 degrees to 28 degrees. The anterior center edge angle of Lequesne (FP) improved from an average of 18 degrees to 28 degrees. The acetabular index angle (AC) improved from an average of 22 degrees to 10 degrees. Major complications included 1 partial lesion of the sciatic nerve, 1 malunion and 1 combined nonunion of the pubic and ischiatic osteotomy. 2 patients underwent subsequent total hip replacement (THR) for progressive osteoarthrosis with pain.

INTERPRETATION

We found good radiographic correction of deformities, improvement of hip function and pain relief with an acceptable complication rate. With appropriate patient selection, this procedure is the most physiological treatment of symptomatic hip dysplasia in young adults. In addition to relieving symptoms, it may prevent and postpone the development of secondary osteoarthrosis.

Arg-vasopressin increases proliferation of human osteoblast-like cells and decreases production of interleukin-6 and macrophage colony-stimulating factor

Patients with arginine-vasopressin (AVP) deficiency have been reported to have a decreased bone mass. The mechanism behind this is not known. In this study, the effects of AVP on primary human osteoblast-like (hOB) cells and SaOS-2 cells were investigated. Cell proliferation was measured by [3H]thymidine incorporation or a commercially available kit (EZ4U), and protein synthesis by [3H]proline incorporation. In addition, the production of interleukin-6 (IL-6) and macrophage colony-stimulating factor (M-CSF) in hOB cells was determined. AVP at 10-100 pmol/l increased cell proliferation in hOB and SaOS-2 cells (p < 0.05). Protein synthesis increased in SaOS-2 cells incubated with 10-100 pmol/l AVP (p < 0.01). When hOB and SaOS-2 cells were incubated with AVP together with a vasopressin receptor-1 (V1)-antagonist ([beta-Mercapto-beta,beta-cyclopenta-methylenepropionyl1,O-Me-Tyr2,Arg8]-vasopressin) or a protein kinase C (PKC)-inhibitor (chelerythrine) the increase in cell proliferation in response to AVP was abolished. The production of IL-6 and M-CSF was decreased in hOB-cells incubated with 10 pmol/l AVP (p < 0.01). In addition, by RT-PCR, we found evidence for expression of mRNA for the vasopressin 1a (V1a)-receptor in hOB cells. In conclusion, AVP stimulated proliferation of hOB- and SaOS-2 cells. We suggest that the effect was mediated through the V1-receptor. Additionally, AVP decreased production of IL-6 and M-CSF from the hOB cells. Moreover, the V1a-receptor seems to be expressed in hOB cells.

Expression of microsomal prostaglandin E synthase 1 in rheumatoid arthritis synovium

OBJECTIVE

Microsomal prostaglandin E synthase 1 (mPGES-1) catalyzes the formation of PGE(2) from cyclooxygenase-derived PGH(2). Microsomal PGES-1 is induced by proinflammatory cytokines and is strongly linked to conditions that result in high PGE(2) biosynthesis. PGE(2) contributes to the pathogenesis of rheumatoid arthritis (RA), acting as a mediator of inflammation and promoting bone destruction. Induction of mPGES-1 in rheumatoid synoviocytes by proinflammatory cytokines has been demonstrated in vitro, indicating an important role in RA pathogenesis. Recent studies using mPGES-1-deficient mice demonstrated the importance of this gene in chronic inflammation. The aim of this study was to investigate the expression and localization of mPGES-1 in synovial biopsy specimens obtained from patients with RA.

METHODS

Synovial tissue samples from 24 patients with RA were obtained, and immunohistologic analysis was performed using polyclonal antibodies against mPGES-1. Double immunofluorescence staining was performed with antibodies to CD3, CD19, CD20, CD68, CD163, and prolyl 4-hydroxylase.

RESULTS

Intracellular mPGES-1 staining was observed in synovial membranes from all of the RA patients studied. Specifically, strong expression of mPGES-1 was detected in synovial lining cells. In sublining mononuclear and fibroblast-like cells, the extent of mPGES-1 staining was less than that in the synovial lining cells. In some patients, positive staining was observed in endothelial cells. With the double immunofluorescence technique, mPGES-1 production was detected in synovial macrophages and fibroblasts, while mPGES-1 expression was not observed in lymphocytes.

CONCLUSION

The demonstration of mPGES-1 expression in synovial tissues from patients with RA suggests a role for mPGES-1 in the RA disease process. Microsomal PGES-1 might be a potential new target for treatment strategies to control PGE(2) synthesis in patients with RA, without the systemic side effects associated with cyclooxygenase inhibitors.

Weak evidence of thyrotropin receptors in primary cultures of human osteoblast-like cells

Extra-thyroidal thyrotropin (TSH) receptors (TSHRs) have been demonstrated in several tissues and cells, including human and rat osteosarcoma cell lines. We have explored whether human TSHR (hTSHRs) also are present in primary cultures of human osteoblast-like (hOB) cells. [(125) I]TSH binding was limited in hOB cells, but somewhat higher in UMR 106-01 cells and considerably higher in hTSHR-transfected CHO cells. In hOB cells, the basal intracellular cAMP levels increased 282% after stimulation with 10 U/L TSH. In the hTSHR-transfected CHO cells, the cAMP increase was 3030% in response to 10 U/L TSH and 1240% after 1 U/L TSH. Free cytoplasmic calcium did not change in response to TSH in hOB cells. HTSHR mRNA was detected in hOB cells from 3/4 bone by reverse transcriptase polymerase chain reaction RT-PCR and nucleotide sequencing HTSHR mRNA, but could not be demonstrated with the RNase protection technique in hOB cells from 5 different donors. In conclusion, even after the use of several methods, we have found only weak evidence for expression and presence of functionally active hTSHR in hOB cells. Given the low level of expression, specific binding and cAMP signaling, we suggest that it is unlikely that circulating TSH plays a physiological role for bone metabolism mediated through osteoblasts.

Variation in the position and orientation of the elbow flexion axis

We analysed the axis of movement in the normal elbow during flexion in vivo using radiostereometric analysis (RSA). The results show an intraindividual variation in the inclination of the axis ranging from 2.1 degrees to 14.3 degrees in the frontal and from 1.6 degrees to 9.8 degrees in the horizontal plane analysed at 30 degrees increments. The inclination of the mean axis of rotation varied within a range of 12.7 degrees in the frontal and 4.6 degrees in the horizontal plane. In both planes, the mean axes were located close to a line joining the centres of the trochlea and capitellum. The intra- and interindividual variations of the axes of flexion of the elbow were greater than previously reported. These factors should be considered in the development of elbow prostheses.

Treadmill training and body weight support for walking after stroke

BACKGROUND

Treadmill training, with some body weight supported using a harness, is a method of treating walking after stroke. Systematic review is required to assess the cost, effectiveness and acceptance of this treatment.

OBJECTIVES

To assess the effectiveness of treadmill training and/or body weight support in the treatment of walking after stroke. The primary outcomes investigated were walking speed and walking dependency.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched 21 March 2003), the Cochrane Central Register of Controlled Trials (Cochrane Library, Issue 1 2003), MEDLINE (1966-March 2003), EMBASE (1980-March 2003), CINAHL (1982-February 2003) and PEDro (last searched 21 March 2003). In addition, we handsearched relevant conference proceedings, screened reference lists and contacted trialists to identify further published and unpublished trials.

SELECTION CRITERIA

Randomised, or quasi-randomised, controlled and cross-over trials of treadmill training and/or body weight support for the treatment of walking after stroke were eligible.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials and extracted data. Trialists were contacted for additional information. A fixed effects model was used for analysis, but if heterogeneity existed (Chi squared statistic) a random effects model was used. Results were analysed as weighted mean differences (WMD) for continuous variables and relative risk (RR) for dichotomous variables. The main outcome variables were walking speed and dependency.

MAIN RESULTS

Eleven trials (458 participants) were included. There were no statistically significant differences between treadmill training, with or without body weight support, and other interventions for walking speed or dependence. There was a small trend toward the effectiveness of treadmill training with body weight support for participants who could walk independently (WMD: 0.24 m/sec, 95% CI: -0.19 to 0.66 for speed; random effects). The one trial which compared treadmill training with and without body weight support showed benefit at the end of follow-up (mean difference: 0.22 m/sec, 95% CI: 0.05 to 0.39). Adverse events occurred slightly more frequently in participants receiving treadmill training, although statistically there were no differences.

REVIEWER'S CONCLUSIONS

Overall, no statistically significant effect of treadmill training and body weight support was detected. However, among people who could walk independently, treadmill training with body weight support appeared to be more effective than other interventions at improving walking speed, but this conclusion was not robust.

Contribution of self-reported health ratings to predicting frailty, institutionalization, and death over a 5-year period

Cross-sectional data from Phase 1 of the Canadian Study of Health and Aging was used to examine the relationship between two self-report health measures: "How would you say your health is these days?"(HEALTH) and "How much do your health troubles stand in the way of your doing the things you want to do?"(TROUBLE). The contribution of these measures to predictive models for institutionalization and mortality is examined, using linked data from Phases 1 and 2. Their relationship to a proposed frailty measure is also examined. At CSHA-1, a majority of respondents perceived that they were in good health and did not feel that their health problems interfered with their preferred activities. At all frailty levels, a majority of both males and females rated their health as "very good" or "pretty good." As frailty increased, health problems increasingly interfered with normal activities. Logistic regression of the longitudinal data indicated that, despite their correlation, HEALTH and TROUBLE cannot act as proxies for each other. They appear to predict independently; adding one to the other significantly improved prediction of institutionalization and mortality.

Cobalt ions influence proliferation and function of human osteoblast-like cells

Cobalt is the major component in many orthopedic implants and the introduction of a second generation of metal on metal bearing prosthesis systems actualizes the toxicity and biocompatibility of this compound. We studied the effect of cobalt ions on primary cultures of human osteoblast-like cells. Cobalt ions dissolved in cell culture medium caused a dose-dependent decrease in proliferation of human osteoblasts measured as (3H)thymidine incorporation. We also found that cobalt ion-enriched medium increased the production of interleukin-6 from the osteoblast-like cells. Furthermore, incubation of osteoblasts with cobalt ion-enriched medium reduced collagen type I and osteocalcin production in a dose-dependent manner when 1,25 dihydroxyvitamin-D3 was added to the culture medium. Cobalt concentrations below 10 microg/mL or 0.17 mmollmL in the cell culture medium had no significant effect on human osteoblast proliferation and function.