Biophysical and enzymatic properties of aminoglycoside adenylyltransferase AadA6 from Pseudomonas aeruginosa

AbstractThe gene coding for the aminoglycoside adenylyltransferase (aadA6) from a clinical isolate of Pseudomonas aeruginosa was cloned and expressed in Escherichia coli strain BL21(DE3)pLysS. The overexpressed enzyme (AadA6, 281 amino-acid residues) and a carboxy-terminal truncated variant molecule ([1-264]AadA6) were purified to near homogeneity and characterized. Light scattering experiments conducted under low ionic strength supported equilibrium between monomeric and homodimeric arrangements of the enzyme subunits. Circular Dichroism spectropolarimetry indicated a close structural relation to adenylate kinases. Both forms modified covalently the aminoglycosides streptomycin and spectinomycin. The enzyme required at least 5mM MgCl2 for normal Michaelis–Menten kinetics. Streptomycin exhibited a strong substrate inhibition effect at 1mM MgCl2. The truncated 17 residues at the C-terminus have little influence on protein folding, whereas they have a positive effect on the enzymic activity and stabilize dimers at high protein concentrations (>100μM). Homology modelling and docking based on known crystal structures yielded models of the central ternary complex of monomeric AadA6 with ATP and streptomycin or spectinomycin

The association between increased body mass index and response to conventional synthetic disease-modifying anti-rheumatic drug treatment in rheumatoid arthritis: results from the METEOR database

Background Few data exist on the association between increased BMI and response to conventional synthetic DMARDs (csDMARDs) in RA. We aimed to explore the association between increased (overweight or obese) BMI on csDMARD prescribing, MTX dose and disease activity over 12 months. Methods Participants in an international RA database were stratified into early (<1 year post-diagnosis) and established RA. EULAR response, 28-joint DAS (DAS28) remission and treatments were recorded at baseline, 6 months and 12 months. Increased BMI was explored in early and established RA as predictors of good EULAR response, DAS28 remission, number of csDMARDs and MTX dose, using logistic and linear regression. Results Data from 1313 patients, 44.3% with early RA, were examined. In early RA, increased BMI was not significantly associated with remission. In established RA, obese patients on monotherapy were significantly less likely to achieve good EULAR response or DAS28 remission at 6 months and more likely to be treated with combination csDMARDs compared with normal BMI. In patients taking MTX, overweight and obese patients with early and established RA were exposed to higher MTX doses (mono- and combination therapy), with a mean dose of 20 mg/week, compared with 15 mg/week in those of normal BMI. Conclusion We observed that compared with patients with normal BMI, overweight and obese individuals experienced more intensive csDMARD exposures. Similar response rates were observed in early RA but increased BMI was associated with reduced response in established RA. Optimization of targeted RA treatment remains important, particularly in those with increased BMI where response in established disease may be attenuated

Body mass index and treatment survival in patients with RA starting treatment with TNF alpha-inhibitors: long-term follow-up in the real-life METEOR registry

Objectives To study whether there is an association between body mass index (BMI) category and survival of various tumour necrosis factor inhibitors (TNFi) in rheumatoid arthritis (RA) patients in a real-life longitudinal international registry.Methods Data from 5230 patients with RA starting treatment with any TNFi were selected from the METEOR registry. Patients were divided into six BMI categories: 3.7% underweight, BMI40 kg/m(2). Time on treatment in the different BMI categories was compared for all TNFi combined and for the infliximab, adalimumab and etanercept separately, using Kaplan-Meier curves and Cox regression analyses. Cox regression analyses were adjusted for potential confounders, with follow-up censored at 5000 days.Results Patients in obesity class II (HR 1.28, 95% CI 1.06 to 1.54) and III (HR 1.67, 95% CI 1.29 to 2.18) and underweight patients (HR 1.30, 95% CI 1.07 to 1.58) showed statistically significantly shorter TNFi survival than normal weight patients. The effect in underweight patients was strongest for infliximab (HR 1.82, 95% CI 1.20 to 2.76), the effect in overweight patients was strongest for infliximab (category II (HR 1.49, 95% CI 0.98 to 2.26); category III (HR 1.46, 95% CI 0.79 to 2.71)) and etanercept (category II (HR 1.27 95% CI 0.98 to 1.65); category III (HR 1.79, 95% CI 1.25 to 2.55)). No significant effect modification from reported pain was found.Conclusion Both underweight and overweight patients discontinued TNFi treatment earlier than normal weight patients, without evidence of reported pain as the main determinant. It remains uncertain what determines TNFi survival in individual patients.Pathophysiology and treatment of rheumatic disease

The long-term course of the Health Assessment Questionnaire in patients with systemic sclerosis

Objective: The Health Assessment Questionnaire-Disability Index is an important outcome measure reflecting functional disability, but knowledge on its course over time in patients with systemic sclerosis is scarce. Therefore, we investigated the long-term course of the Health Assessment Questionnaire-Disability Index and its association with baseline characteristics in systemic sclerosis patients. Methods: Systemic sclerosis patients, fulfilling the European League Against Rheumatism and the American College of Rheumatology 2013 criteria, were included from the Leiden Combined Care in Systemic Sclerosis cohort with annual assessments including the Scleroderma Health Assessment Questionnaire-Disability Index (range = 0-3). The course of the Health Assessment Questionnaire-Disability Index was evaluated over the total follow-up (baseline to last available Health Assessment Questionnaire-Disability Index) and between yearly visits. Based on a minimal clinical important difference of 0.22, courses were categorized into worsening, stable or improvement. The course of the Health Assessment Questionnaire-Disability Index over time was evaluated with linear mixed models. Baseline characteristics were compared between patients with a worsening or improvement of the Health Assessment Questionnaire-Disability Index over the total follow-up period with logistic regression analyses. Results: A total of 517 systemic sclerosis patients were included, with a median follow-up of 7 years (interquartile range = 4-9; 2649 visits) and a baseline Health Assessment Questionnaire-Disability Index of 0.625 (interquartile range = 0.125-1.25). On group level, the Health Assessment Questionnaire-Disability Index is stable with an annual increase of 0.019 (95% confidence interval = 0.011 to 0.027). Looking at subgroups, patients >65 years or who died/were physically unable to come during follow-up had a worse mean Health Assessment Questionnaire-Disability Index. In individual courses from baseline to the last follow-up, the proportions of patients with a clinically meaningful worsening, stable or improved Health Assessment Questionnaire-Disability Index were 35%, 42% and 23%, respectively. Patients with immunosuppressants (odds ratio = 0.5, 95% confidence interval = 0.3 to 0.9) or gastrointestinal involvement (odds ratio = 0.6, 95% confidence interval = 0.4 to 0.9) at baseline showed a reduced chance of worsening of the Health Assessment Questionnaire-Disability Index over the total follow-up period. Conclusion: Over time, the average course of the Health Assessment Questionnaire-Disability Index was stable in systemic sclerosis patients. However, individual courses vary, with worsening occurring in one-third. Worsening occurred less often in individuals using immunosuppressants or with gastrointestinal involvement at baseline.Pathophysiology and treatment of rheumatic disease

Worldwide treatment opportunities of rheumatoid arthritis

In this thesis we aimed to investigate ways to optimize treatment strategies and the choice of treatment for individual patients, to be implemented in a worldwide context. Although major advances have been made in the treatment of RA, it is still uncertain which treatment is the best choice for each individual patient. This can result in both overtreatment and undertreatment, increasing the burden of RA for patients as well as for society. In clinical trials and daily practice there appears to be a development towards earlier treatment, with higher dosages of medication and more stringent treatment targets. In part 1 of this thesis, some of these developments were investigated and challenged. In countries across the world, patients do not benefit similarly from recent advances in the treatment of RA. In part 2 of this thesis, we aimed to identify contributing factors to inequalities in access to treatment and care and clinical outcomes across countries, as a first step towards improvement.</p

Worldwide treatment opportunities of rheumatoid arthritis

In this thesis we aimed to investigate ways to optimize treatment strategies and the choice of treatment for individual patients, to be implemented in a worldwide context. Although major advances have been made in the treatment of RA, it is still uncertain which treatment is the best choice for each individual patient. This can result in both overtreatment and undertreatment, increasing the burden of RA for patients as well as for society. In clinical trials and daily practice there appears to be a development towards earlier treatment, with higher dosages of medication and more stringent treatment targets. In part 1 of this thesis, some of these developments were investigated and challenged. In countries across the world, patients do not benefit similarly from recent advances in the treatment of RA. In part 2 of this thesis, we aimed to identify contributing factors to inequalities in access to treatment and care and clinical outcomes across countries, as a first step towards improvement.LUMC / Geneeskund

Health inequalities across patients with early inflammatory arthritis of different ethnicities: what could be the driving factors?

Pathophysiology and treatment of rheumatic disease

What is the optimal target for treat-to-target strategies in rheumatoid arthritis?

Pathophysiology and treatment of rheumatic disease