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A semiphysiologically based pharmacokinetic (semi-PBPK) population model was used to evaluate the influence of enterohepatic recycling and protein binding, as well as the effect of genetic variability in CYP1A2, CYP2C19, and ABCG2, on the large interindividual variability of teriflunomide (active metabolite) concentrations following leflunomide administration in rheumatoid arthritis (RA) patients. The model was developed with total and free teriflunomide concentrations determined in RA patients taking leflunomide, as well as mean teriflunomide concentrations following the administration of leflunomide or teriflunomide extracted from the literature. Once developed, the 15-compartment model was able to predict total and free teriflunomide concentrations and was used to screen demographic and genotypic covariates, of which only fat-free mass and liver function (ALT) improved prediction. This approach effectively evaluated the effects of multiple covariates on both total and free teriflunomide concentrations, which have only been explored previously through simplistic one-compartment models for total teriflunomide. [ABSTRACT FROM AUTHOR]

Objective: We undertook a comprehensive cross-sectional analysis of a multicentred Australian cohort of systemic sclerosis (SSc) patients to evaluate the associations of anti-Ro52/TRIM21 with SSc pulmonary involvement. Method: The study included 596 patients from the Australian Scleroderma Cohort Study database whose anti-Ro52/TRIM21 status was known. Anti-Ro52/TRIM21 was measured via line immunoassay. Data on demographic variables, autoantibody profiles, presence of interstitial lung disease (ILD), presence of pulmonary arterial hypertension (PAH), oxygen saturation, Six-Minute Walk Test distance, Borg dyspnoea score, and lung function tests were extracted. SPSS software was used to examine associations using univariate and multivariate analyses. Results: Anti-Ro52/TRIM21 was present in 34.4% of SSc patients. In the cross-sectional analysis, anti-Ro52/TRIM21 was independently associated with PAH [odds ratio 1.75, 95% confidence interval (CI) 1.05–2.90], but not ILD or other surrogate measures of pulmonary involvement such as average patient oxygen saturation. The antibody, however, was also associated with a higher forced vital capacity/diffusing capacity of the lung for carbon monoxide ratio. Prospectively, anti-Ro52/TRIM21 was also associated with an increased risk of death in patients with SSc (hazard ratio 1.62, 95% CI 1.11–2.35), independent of confounding factors. The primary cause of death appeared to be related to PAH and/or ILD, and anti-Ro52/TRIM21 was associated with PAH-related complications. Conclusion: Anti-Ro52/TRIM21 was independently associated with PAH and mortality in SSc patients. Future longitudinal studies are recommended to investigate the timing and pathogenic mechanisms of this autoantibody in PAH. [ABSTRACT FROM AUTHOR]

Summary A system has been established to assess the recruitment of 99mTc-hexamethylpropylene amine oxamine (99mTc-HMPAO)-labelled PBMC and [125I]iododeoxyuridine-labelled Con A stimulated lymphoblasts to allogeneic human synovial xenografts in the ears of SCID mice. Successful engraftment of osteoarthritic synovium was achieved in approximately 90% of cases and a connection between the human microvasculature of the xenograft and the circulation of the mouse was shown. Cells were delivered to the xenograft by a system of regional vascular perfusion, thus avoiding the major murine vascular beds. The accumulation of 99mTc-HMPAO-labelled PBMC in mouse ears was monitored in real time. Direct injection of xenograft-bearing ears with recombinant human TNF-α, 7 h prior to perfusion, increased the accumulation of both PBMC and lymphoblasts in cytokine-injected ears compared to contralateral control-injected ears. Autoradiography revealed the presence of [125I]iododeoxyuridine-labelled lymphoblasts associated with human microvasculature within the xenograft. However, the increased accumulation of lymphoblasts in cytokine-injected ears occurred in the tissues surrounding the xenograft, where lymphoblasts were associated more often with murine than human vessels. Although the system described offers advantages over similar models, the propensity for mouse endothelium to interact with human leucocytes is likely to be a generic disadvantage for models of human leucocyte recruitment to xenografts in immunodeficient mice. [ABSTRACT FROM AUTHOR]