Rejection of persistent‐bounded disturbances in continuous time‐delay systems using observer‐based feedback

In this paper, the problem of persistent‐bounded disturbance rejection of linear continuous‐time systems with time‐varying delays is investigated using the tools of invariant set analysis and Lyapunov‐function methodology. We derive less conservative sufficient conditions on robust attractor for time‐delay systems in terms of strict linear matrix inequalities (LMIs) to guarantee the desired ??₁‐performance. A robust output‐feedback controller is designed and the associated gain is determined using strict LMIs. The developed results are tested on two representative time‐delay examples. Copyright © 2009 John Wiley & Sons, Ltd.     

Decreasing plasma soluble IL‐1 receptor antagonist and increasing monocyte activation early post‐transplant may be involved in pathogenesis of delayed graft function in renal transplant recipients

Sadeghi M, Daniel V, Naujokat C, Schmidt J, Mehrabi A, Zeier M, Opelz G. Decreasing plasma soluble IL‐1 receptor antagonist and increasing monocyte activation early post‐transplant may be involved in pathogenesis of delayed graft function in renal transplant recipients
Clin Transplant 2010: 24: 415–423. © 2009 John Wiley & Sons A/S. Abstract: Delayed graft function (DGF) increases the risk of acute allograft rejection and may affect long‐term graft survival. We compared pre‐transplant, early post‐transplant, and late post‐transplant serum creatinine (Cr) and plasma levels of neopterin, cytokines, and cytokine receptors/antagonists in patients with DGF (n = 39), slow graft function (SGF) (n = 43), or immediate graft function (IGF) (n = 30). Three and eight days post‐transplant, plasma neopterin (p < 0.001; p < 0.001), Soluble Interleukin‐6 (IL‐6) receptor (R) (p = 0.002; p = 0.001), and IL‐10 (p = 0.003; p = 0.001) were higher in DGF than IGF patients. One month post‐transplant, plasma neopterin (p < 0.001) and IL‐10 (p < 0.001) were higher in DGF than IGF patients. Three days post‐transplant, the results indicated reduced sIL‐1 receptor antognist (RA) production in DGF patients (p = 0.001). Simultaneously, plasma sIL‐6R and IL‐10 increased in DGF (p < 0.001; p = 0.003) and SGF (p = 0.007; p = 0.030) patients, indicating increased production of sIL‐6R and IL‐10. Lower sIL‐1 production in DGF than IGF patients early post‐transplant might promote the increased production of monocyte‐derived neopterin, sIL‐6R, and IL‐10. This monocyte/macrophage activation might induce inflammation in the graft and subsequently cause an impairment of graft function. Blocking of monocyte activity after renal transplantation may be considered a potential approach for improving graft outcome.     

Single-stage medial plateau elevation and metaphyseal osteotomies in advanced-stage Blount’s disease: a new technique

PurposeSurgical treatment in advanced-stage infantile Blount’s disease with medial plateau (MP) depression is challenging. Several osteotomies and fixation methods have been described with no established benchmark. We conducted this study to evaluate the efficacy and safety of a new single-stage technique for acute medial condyle elevation and metaphyseal osteotomies with internal fixation.MethodsA prospective case series of 19 consecutive patients (21 knees) with severe infantile Blount’s disease underwent a single-stage MP elevation and metaphyseal osteotomies, with internal fixation. The mean age was 10.3 years (8.2 to 13.6) and the mean follow-up was 5.1 years (3.2 to 8.3). The outcome measures included clinical and radiological parameters and patient-reported pediatric outcomes data collection instrument (PODCI) score.ResultsThe mean PODCI score improved significantly from 50% to 88%. The mean internal tibial torsion improved from -27° to 11°. All cases maintained full knee extension, no limitation in flexion range of movement and no signs of instability or lateral thrust gait. All the radiographic parameters improved significantly; the mean tibiofemoral angle improved from -29° to 7°, the metaphyseal-diaphyseal angle improved from 33.4° to 4.7° and the angle of depressed MP improved from 38.3° to 2.4° (p < 0.001). At the latest follow-up, no cases of deformity recurrence were identified, the final limb-length discrepancy was < 1 cm in all patients.ConclusionSingle-stage MP elevation and metaphyseal osteotomies with internal fixation significantly improved the clinical and radiographic parameters and PODCI score in advanced infantile Blount’s disease and precluded the use of external immobilization, with no evidence of deformity recurrence.Level of evidenceIV     

Level of Education and Gender-specific Self-reported Oral Health Behavior Among Dental Students

Purpose: To identify the oral health attitudes/behaviour among dental students in Jordan, and analyse the variations in oral health attitudes based on gender and level of education. Materials and Methods: Out of the 653 registered dental students at the faculty of dentistry, 580 students (455 females and 125 males, mean age = 20.1 ± 1.6 years) participated in the study (response rate 89%). The Hiroshima University-Dental Behavioural Inventory (HU-DBI) was used to assess oral heath attitudes and behaviour of the participants. Data were analysed using the chi-square test, and statistical significance was set at P < 0.05. Results: Females had better oral health attitudes and behaviour, especially towards visiting the dentist, toothbrushing habits and oral hygiene practice (P < 0.05). Also, students from the higher years had better oral health attitudes, behaviour and knowledge, especially towards gingival health, oral hygiene practice, toothbrushing and visiting the dentist (P < 0.05). Conclusion: Dental students in Jordan had poor oral health attitudes and behaviour. Females had better oral health knowledge, attitudes and behaviour than males. With increasing years of study, some aspects of dental students' oral health behaviour and attitudes improved. However, this improvement was limited and students should be encouraged to become an example of oral health for their society. Better comprehensive dental education with early exposure to dental health and prevention was suggested to improve dental students' oral health attitudes and behaviour.     

Differential expression of interferon gamma by mitogen-stimulated peripheral blood mononuclear cells among Kuwaiti psoriasis patients

Most diseases exhibit characteristic profiles of cytokine expression, broadly subdivided into Th1, involving primarily cell-mediated responses, of which Interferon-gamma (INF-gamma), Interleukin-2 (IL-2) and Tumor Necrosis Factor-alpha (TNF-alpha) are hallmarks, and Th2 processes, which often involve activation of the humoral arm of the immune system, resulting in elevated levels of IL-4, IL-5 and IL-10. Psoriasis, a disorder characterized by disfiguring skin lesions and elevated levels of activated CD4+ T helper lymphocytes in both peripheral blood and lesional tissue, exhibits a profile of cytokine expression that includes high levels of TNF-alpha and IFN-gamma, with low IL-5 and IL-10, indicating that immunologically, the pathogenesis of the disease is Th1. In this study, we report the results of an investigation of peripheral blood mononuclear cell cytokine expression among Kuwaiti psoriasis patients; we demonstrated two patterns of IFN-gamma production which may suggest differing pathogeneses. Whole, haparinized blood was donated by 17 patients with active psoriasis and 11 healthy control subject. Mononuclear cells were isolated by density centrifugation and cultured for 3 days in the presence or absence of a mitogen (PHA). Supernatants were assayed for IFN-gamma (a Th1 marker) and IL-10 (a Th2 marker) by enzyme-linked immunoabsorption assay (ELISA). IFN-gamma expression by both PHA-stimulated and unstimulated cultures from psoriatics significantly exceeded that of controls (p < 0.001), whereas no significant differences in IL-10 expression were noted between psoriatic and control subjects. Stimulation indices (cytokine concentration in PHA-stimulated/unstimulated cultures, SI) for psoriatic subjects were significantly higher than those of controls for IFN-gamma (p = 0.000), but not for IL-10. Ratios of SI (SI IFN-gamma/SL IL-10) for the psoriatic subjects also were significantly greater for the psoriatic subjects than for the controls (p = 0.003). However, within the psoriatic group, eight patients failed to show the expected elevation of IFN-gamma/IL-10 ratio as a result of high unstimulated levels of IFN-gamma production. The divergence of IFN-gamma expression within the psoriatic group may indicate two different modes of T lymphocyte activation contributing to the pathogenesis of psoriasis in this study.