Bijlsma, J.W.J.

SMC6 is an essential gene in mice, but a hypomorphic mutant in the ATPase domain has a mild phenotype with a range of subtle abnormalities (Article)

2013-03-19T00:00:00Z

Smc5-6 is a highly conserved protein complex related to cohesin and condensin involved in the structural maintenance of chromosomes. In yeasts the Smc5-6 complex is essential for proliferation and is involved in DNA repair and homologous recombination. siRNA depletion of genes involved in the Smc5-6 complex in cultured mammalian cells results in sensitivity to some DNA damaging agents. In order to gain further insight into its role in mammals we have generated mice mutated in the Smc6 gene. A complete knockout resulted in early embryonic lethality, demonstrating that this gene is essential in mammals. However, mutation of the highly conserved serine-994 to alanine in the ATP hydrolysis motif in the SMC6 C-terminal domain, resulted in mice with a surprisingly mild phenotype. With the neo gene selection marker in the intron following the mutation, resulting in reduced expression of the SMC6 gene, the mice were reduced in size, but fertile and had normal lifespans. When the neo gene was removed, the mice had normal size, but detailed phenotypic analysis revealed minor abnormalities in glucose tolerance, haematopoiesis, nociception and global gene expression patterns. Embryonic fibroblasts derived from the ser994 mutant mice were not sensitive to killing by a range of DNA damaging agents, but they were sensitive to the induction of sister chromatid exchanges induced by ultraviolet light or mitomycin C. They also accumulated more oxidative damage than wild-type cells.

Cross-sectional and predictive associations between plasma adipokines and radiographic signs of early-stage knee osteoarthritis: Data from CHECK (Article)

2012-11-01T00:00:00Z

Objective: To investigate cross-sectional and predictive associations of plasma adipokines with biochemical markers of systemic joint metabolism and radiographic signs of early-stage knee osteoarthritis (OA). Design: The adipokines pLeptin, pAdiponectin, and pResistin, the cartilage markers C-terminal telopeptide of type II collagen (uCTX-II), N-terminal propeptide of type IIA procollagen (sPIIANP), chondroitin sulfate 846 (sCS846), and cartilage oligomeric matrix protein (sCOMP), and the synovial markers hyaluronic acid (sHA) and N-terminal propeptide of type III procollagen (sPIIINP) were assessed by enzyme-linked immunosorbent assay or radioactive immunoassay in baseline samples of Cohort Hip and Cohort Knee (CHECK), a cohort of 1002 subjects with early-stage symptomatic knee and/or hip OA. Knee radiographs were obtained at baseline and after 2 and 5 years and scored according to Kellgren and Lawrence. Results: pLeptin showed positive associations with uCTX-II, sCOMP, sPIIANP, sHA, and sPIIINP, and with presence and progression of radiographic knee OA. Associations expectedly disappeared after adjustment for body mass index. pResistin showed positive associations with sPIIINP and present and incident radiographic knee OA that were largely independent of BMI. pAdiponectin showed positive associations with uCTX-II and sCOMP. Furthermore, pAdiponectin did not show associations with radiographic knee OA on itself, but associations of pResistin with present radiographic knee OA were stronger in higher pAdiponectin tertiles (P = 0.024 for interaction between pAdiponectin and pResistin). Although statistically significant, all associations were weak. Conclusions: Adipokines may have aggravating, although may be minor, structural effects in early-stage knee OA.

Detection of progression of radiographic joint damage in case of very early osteoarthritis: Sensitivity to change of quantitative analysis compared to qualitative grading (Article)

2012-11-01T00:00:00Z

For more tailored treatment of osteoarthritis it is worthy to identify different subpopulations early in the disease. Objective of this study is to evaluate whether the sensitivity to detect progression of radiographic features, which may add to this identification, can be improved by quantitative measurement (using Knee Images Digital Analysis; KIDA), compared to qualitative grading (according to the Altman atlas). Among individuals with early signs related to osteoarthritis (Cohort Hip and Cohort Knee, Check) symptomatic knees (n=1082) were selected. Standardized baseline and two-year follow-up radiographs were evaluated for joint space narrowing, osteophyte formation, and bone density changes using KIDA measurement and Altman scales. Sensitivity to change was determined by calculating the standardized response mean (SRM). For all distinct KIDA parameters, the smallest detectable difference was calculated to define radiographic changes at the individual level. The percentage of knees that changed was compared between KIDA measurement and Altman grading. Also agreement between both methods was evaluated. Studying radiographic progression in knees with early signs related to osteoarthritis showed, for all KIDA and Altman parameters, a small SRM and radiographic change in a small percentage of knees. The sensitivity to detect radiographic progression was similar for KIDA measurement and Altman grading. However, agreement between the Altman and KIDA method was limited (kappa ≤0.20). Although sensitivity to change is limited, similar for KIDA measurement and Altman grading, this may not exclude that measurement of separate features might be useful to distinguish subpopulations of osteoarthritis later in the disease.

Assessment of Helicobacter pylori eradication in patients on NSAID treatment (Article)

2012-09-24T00:00:00Z

Background: In this post-hoc analysis of a randomized, double blind, placebo controlled trial, we measured the sensitivity and specificity of Helicobacter pylori IgG-antibody titer changes, hematoxylin and eosin (H&E) stains, immunohistochemical (IHC) stains and culture results in NSAID using patients, following H. pylori eradication therapy or placebo.Methods: 347 NSAID using patients who were H. pylori positive on serological testing for H. pylori IgG-antibodies were randomized for H. pylori eradication therapy or placebo. Three months after randomization, gastric mucosal biopsies were taken for H. pylori culture and histological examination. At 3 and 12 months, blood samples were taken for repeated serological testing. The gold standard for H. pylori infection was based on a positive culture or both a positive histological examination and a positive serological test. Sensitivity, specificity and receiver operating curves (ROC) were calculated.Results: H. pylori eradication therapy was successful in 91% of patients. Culture provided an overall sensitivity of 82%, and 73% after eradication, with a specificity of 100%. Histological examination with either H&E or IHC stains provided sensitivities and specificities between 93% and 100%. Adding IHC to H&E stains did not improve these results. The ROC curve for percent change in H. pylori IgG-antibody titers had good diagnostic power in identifying H. pylori negative patients, with an area under the ROC curve of 0.70 (95 % CI 0.59 to 0.79, P = 0.085) at 3 months and 0.83 (95% CI 0.76 to 0.89, P < 0.0001) at 12 months. A cut-off point of at least 21% decrease in H. pylori IgG-antibody titers at 3 months and 58% at 12 months provided a sensitivity of 64% and 87% and a specificity of 81% and 74% respectively, for successful eradication of H. pylori.Conclusions: In NSAID using patients, following H. pylori eradication therapy or placebo, histological examination of gastric mucosal tissue biopsies provided good sensitivity and specificity ratios for evaluating success of H. pylori eradication therapy. A percentual H. pylori IgG-antibody titer change has better sensitivity and specificity than an absolute titer change or a predefined H. pylori IgG-antibody titer cut-off point for evaluating success of H. pylori eradication therapy.

Clusters within a wide spectrum of biochemical markers for osteoarthritis: Data from CHECK, a large cohort of individuals with very early symptomatic osteoarthritis (Article)

2012-07-01T00:00:00Z

Objective: To assess a wide spectrum of biochemical markers (biomarkers) in a large cohort of individuals with (very) early symptomatic knee and/or hip osteoarthritis (OA). Secondly, to investigate associations between biomarkers and between biomarkers and demographics to demonstrate validity of the obtained dataset and further investigate the involvement and/or role of these biomarkers in OA. Design: Fourteen biomarkers (uCTX-II, uCTX-I, uNTX-I, sCOMP, sPIIANP, sCS846, sC1,2C, sOC, sPINP, sHA, sPIIINP, pLeptin, pAdiponectin, pResistin) were assessed by ELISA or RIA in CHECK (Cohort Hip and Cohort Knee), a 10-year prospective cohort of 1,002 individuals with early symptomatic knee and/or hip OA. Results: Quality controls revealed that gathered data were technically reliable. The majority of biomarkers showed relevant associations with demographic variables, which were expectedly different between genders and/or menopausal status for some. Principal component analysis enabled identification of five clusters, consecutively designated as 'bone-CTX-II', 'inflammation', 'synovium', 'C1,2C-adipokines', and 'cartilage synthesis' cluster. Notably, uCTX-II clustered with biomarkers of bone metabolism, while sCOMP clustered with biomarkers of synovial activity. Conclusions: The identified clusters extended knowledge on individual biomarkers from mostly smaller studies as did the observed associations between biomarker levels and demographics, from which validity of our data was deduced. uCTX-II may not only reflect articular cartilage but also bone metabolism and sCOMP may reflect synovial rather than cartilage metabolism. Major involvement of adipokines in joint metabolism was not identified.

Evaluation of separate quantitative radiographic features adds to the prediction of incident radiographic osteoarthritis in individuals with recent onset of knee pain: 5-year follow-up in the CHECK cohort (Article)

2012-06-01T00:00:00Z

Objective: Detailed radiographic evaluation might enable the identification of osteoarthritis (OA) earlier in the disease. This study evaluated whether and which separate quantitative features on knee radiographs of individuals with recent onset knee pain are associated with incidence of radiographic OA and persistence and/or progression of clinical OA during 5-year follow-up. Method: From the Cohort Hip & Cohort Knee study participants with knee pain at baseline were evaluated. Radiographic OA development was defined as Kellgren & Lawrence (K&L) grade ≥II at 5-year follow-up. Clinical OA was defined as persistent knee pain and as progression of Westen Ontario & McMaster Universities Osteoarthritis index (WOMAC) pain and function score during follow-up. At baseline radiographic damage was determined by quantitative measurement of separate features using Knee Images Digital Analysis, and by K&L-grading. Results: Measuring osteophyte area [odds ratio (OR) = 7.0] and minimum joint space width (OR = 0.7), in addition to demographic and clinical characteristics, improved the prediction of radiographic OA 5 years later [area under curve receiver operating characteristic = 0.74 vs 0.64 without radiographic features]. When the predictive score (based on multivariate regression coefficients) was larger than the cut-off for optimal specificity, the chance of incident radiographic OA was 54% instead of the prior probability of 19%. Evaluating separate quantitative features performed slightly better than K&L-grading (AUC = 0.70). Radiographic characteristics hardly added to prediction of clinical OA. Conclusion: In individuals with onset knee pain, radiographic characteristics added to the prediction of radiographic OA development 5 years later. Quantitative radiographic evaluation in individuals with suspected OA is worthwhile when determining treatment strategies and designing clinical trials.

In early OA, thinning of the subchondral plate is directly related to cartilage damage: results from a canine ACLT-meniscectomy model (Article)

2010-05-01T00:00:00Z

Abstract OBJECTIVE: The pathogenesis of osteoarthritis (OA) includes cartilage degeneration, synovial inflammation, and bone changes. Slowly, the sequence and inter-relationship of these features is becoming clearer. Early models of OA suggest thinning of the subchondral plate in addition to trabecular bone changes. In the present study subchondral bone changes were studied in the canine anterior cruciate ligament transection (ACLT)-meniscectomy model. This model is characterized by intra-joint variability with respect to cartilage damage (predominantly medial) and loading (lateral unloading due to a shifted axis). METHODS: In 13 Labrador dogs, OA was induced by transection of the anterior cruciate ligament and removal of the medial meniscus. Twelve weeks later, cartilage integrity was evaluated histologically using the modified Mankin score (0-11), and proteoglycan content was determined by Alcian Blue assay. Bone architecture of the tibia was quantified by micro-CT. RESULTS: Cartilage damage was severe in the medial compartment (Mankin score +3.5, glycosaminoglycan (GAG) content -28%) and mild in the lateral compartment (Mankin score +1.6, GAG content -15%). Thinning and porosity of the subchondral plate were only present on the medial side (-21%, +87%, respectively). Interestingly, changes in trabecular bone structure did almost not occur in the medial compartment (volume fraction -7%) but were clear in the lateral compartment (-20%). CONCLUSION: Thinning of the subchondral plate is a localized phenomenon related to cartilage degeneration while trabecular bone changes are related to mechanical (un)loading. The different mechanisms responsible for bone changes in OA should be taken in account when designing and interpreting studies interfering with bone turnover in the treatment of OA.

EULAR evidence-based recommendations for the diagnosis of knee osteoarthritis (Article)

2010-03-01T00:00:00Z

Objective: To develop evidence-based recommendations for the diagnosis of knee osteoarthritis (OA). Methods: The multidisciplinary guideline development group, representing 12 European countries, generated 10 key propositions regarding diagnosis using a Delphi consensus approach. For each recommendation, research evidence was searched systematically. Whenever possible, the sensitivity, specificity and likelihood ratio were calculated for individual diagnostic indicators and a diagnostic ladder was developed using Bayes' method. Secondary analyses were undertaken to test directly the recommendations using multiple predictive models in two populations from the UK and the Netherlands. Strength of recommendation was assessed by the EULAR visual analogue scale. Results: Recommendations covered the definition of knee OA and its risk factors, subsets, typical symptoms and signs, the use of imaging and laboratory tests and differential diagnosis. Three symptoms (persistent knee pain, limited morning stiffness and reduced function) and three signs (crepitus, restricted movement and bony enlargement) appeared to be the most useful. Assuming a 12.5% background prevalence of knee OA in adults aged ≥45 years, the estimated probability of having radiographic knee OA increased with increasing number of positive features, to 99% when all six symptoms and signs were present. The performance of the recommendations in the study populations varied according to the definition of knee OA, background risk and number of tests applied. Conclusion: 10 key recommendations for diagnosis of knee OA were developed using both research evidence and expert consensus. Although there is no agreed reference standard, thorough clinical assessment alone can provide a confident rule-in diagnosis.

CHECK (Cohort Hip and Cohort Knee): Similarities and differences with the Osteoarthritis Initiative (Article)

2009-09-01T00:00:00Z

Objective: To describe the osteoarthritis study population of CHECK (Cohort Hip and Cohort Knee) in comparison with relevant selections of the study population of the Osteoarthritis Initiative (OAI) based on clinical status and radiographic parameters. Methods: In The Netherlands a prospective 10-year follow-up study was initiated by the Dutch Arthritis Association on participants with early osteoarthritisrelated complaints of hip and/or knee: CHECK. In parallel in the USA an observational 4-year follow-up study, the OAI, was started by the National Institutes of Health, on patients with or at risk of symptomatic knee osteoarthritis. For comparison with CHECK, the entire cohort and a subgroup of individuals excluding those with exclusively hip pain were compared with relevant subpopulations of the OAI. Results: At baseline, CHECK included 1002 participants with in general similar characteristics as described for the OAI. However, significantly fewer individuals in CHECK had radiographic knee osteoarthritis at baseline when compared with the OAI (p<0.001). In contrast, at baseline, the CHECK cohort reported higher scores on pain, stiffness and functional disability (Western Ontario and McMaster osteoarthritis index) when compared with the OAI (all p<0.001). These differences were supported by physical health status in contrast to mental health (Short Form 36/12) was at baseline significantly worse for the CHECK participants (p<0.001). Conclusion: Although both cohorts focus on the early phase of osteoarthritis, they differ significantly with respect to structural (radiographic) and clinical (health status) characteristics, CHECK expectedly representing participants in an even earlier phase of disease.

Helicobacter pylori eradication in patients on long-term treatment with NSAIDs reduces the severity of gastritis: A randomized controlled trial (Article)

2009-02-01T00:00:00Z

BACKGROUND: Maintenance use of nonsteroidal anti-inflammatory drugs (NSAIDs) is often complicated by gastropathy. In non-NSAID users, eradication of Helicobacter pylori is associated with decreased mucosal inflammation, and may halt the progression to atrophy and intestinal metaplasia, but the continuous use of NSAIDs may interfere with these processes. GOAL: To investigate the effect of H. pylori eradication on gastric mucosal histology during long-term NSAID use, with and without gastroprotective therapy. STUDY: Patients were eligible for inclusion if they were on long-term NSAIDs and were H. pylori-positive on serologic testing. Patients were randomly assigned to either eradication or placebo. Gastritis was assessed according to the updated Sydney classification for activity, chronic inflammation, gastric glandular atrophy, intestinal metaplasia, and H. pylori density. RESULTS: Biopsy specimens were available for histology of 305 patients. Of these, 48% were on chronic gastroprotective medication. Significant less active gastritis, inflammation, and H. pylori density was found in the eradication group compared with the placebo group in both corpus and antrum (P<0.001). In the corpus, less atrophy was found in the eradication group compared with the placebo group. CONCLUSIONS: H. pylori eradication in patients on long-term NSAID therapy leads to healing of gastritis despite ongoing NSAID therapy.

Eradication of Helicobacter pylori does not reduce the incidence of gastroduodenal ulcers in patients on long-term NSAID treatment: Double-blind, randomized, placebo-controlled trial (Article)

2007-10-01T00:00:00Z

Background: Helicobacter pylori and nonsteroidal antiinflammatory drugs (NSAIDs) are the major causes of gastroduodenal ulcers. Studies on the benefit of eradication of H. pylori in NSAID users yielded conflicting results. Objective: To investigate whether H. pylori eradication in patients on long-term NSAIDs reduces the incidence of gastroduodenal ulcers. Methods: Patients on long-term NSAID treatment and who are H. pylori positive on serologic testing, were randomly assigned to either H. pylori eradication (omeprazole, amoxicillin, and clarithromycin) or placebo. Primary endpoint was the presence of endoscopic gastric or duodenal ulcers 3 months after randomization. Results: One hundred sixty-five (48%) of a total of 347 patients were on gastroprotective medication. At endoscopy, gastroduodenal ulcers were diagnosed in 6 (4%) and 8 (5%) patients in the eradication and placebo group, respectively (p =.65). During follow-up of 12 months, no symptomatic ulcers or ulcer complications developed. No significant differences were found in the development of gastroduodenal erosions, dyspepsia, or in quality of life. Conclusion: H. pylori eradication therapy in patients on long-term NSAID treatment had no beneficial effect on the occurrence of ulcers, erosions, or dyspepsia. Ulcer rates in both study arms are remarkably low, in both patients with and without gastroprotective therapy.