Prevalence, significance and predictive value of antiphospholipid antibodies in Crohn's disease

AIM: To assess the prevalence and stability of different antiphospholipid antibodies(APLAs) and their association with disease phenotype and progression in inflammatory bowel diseases(IBD) patients.METHODS: About 458 consecutive patients [Crohn's disease(CD): 271 and ulcerative colitis(UC): 187] were enrolled into a follow-up cohort study in a tertiary IBD referral center in Hungary. Detailed clinical phenotypes were determined at enrollment by reviewing the patients' medical charts. Disease activity, medical treatment and data about evolvement of complications or surgical interventions were determined prospectively during the follow-up. Disease course(development f complicated disease phenotype and need for surgery),occurrence of thrombotic events, actual state of diseaseactivity according to clinical, laboratory and endoscopic scores and accurate treatment regime were recorded during the follow-up,(median, 57.4 and 61.6 mo for CD and UC). Sera of IBD patients and 103 healthy controls(HC) were tested on individual anti-β2-Glycoprotein-I(anti-β2-GPI IgA/M/G), anti-cardiolipin(ACA IgA/M/G)and anti-phosphatidylserine/prothrombin(anti-PS/PT IgA/M/G) antibodies and also anti-Saccharomyces cerevisiae antibodies(ASCA IgA/G) by enzyme-linked immunosorbent assay(ELISA). In a subgroup of CD(n = 198) and UC patients(n = 103), obtaining consecutive samples over various arbitrary timepoints during the disease course, we evaluated the intraindividual stability of the APLA status. Additionally,we provide an overview of studies, performed so far, in which significance of APLAs in IBD were assessed.RESULTS: Patients with CD had significantly higher prevalence of both ACA(23.4%) and anti-PS/PT(20.4%) antibodies than UC(4.8%, p < 0.0001 and10.2%, p = 0.004) and HC(2.9%, p < 0.0001 and15.5%, p = NS). No difference was found for the prevalence of anti-β2-GPI between different groups(7.2%-9.7%). In CD, no association was found between APLA and ASCA status of the patients.Occurrence of anti-β2-GPI, ACA and anti-PS/PT was not different between the group of patients with active vs inactive disease state according to appropriate clinical, laboratory and endoscopic scores in CD as well as in UC patients. All subtypes of anti-β2-GPI and ACA IgM status were found to be very stable over time, in contrast ACA IgG and even more ACA IgA status showed significant intraindividual changes.Changes in antibody status were more remarkable in CD than UC(ACA IgA: 49.9% vs 23.3% and ACA IgG:21.2% vs 5.8%). Interestingly, 59.1% and 30.1% of CD patients who received anti-TNF therapy showed significant negative to positive changes in ACA IgA and IgG antibody status respectively. APLA status was not associated with the clinical phenotype at diagnosis or during follow-up, medical therapy, or thrombotic events and it was not associated with the probability of developing complicated disease phenotype or surgery in a Kaplan-Meier analysis.CONCLUSION: The present study demonstrated enhanced formation of APLAs in CD patients. However,presence of different APLAs were not associated with the clinical phenotype or disease course.

Development of Wearable Micro-actuator Array for 3-D Virtual Tactile Displays

A novel 4 by 4 array of electromagnetic micro-actuators operating on the principle of voice-coil actuators is presented. The intended application of the array is dynamic tactile stimulation, where multiple actuators generate an illusion of touching a moving pattern. In comparison to earlier designs [1-3], the device has smaller dimensions of 2.28 mm in diameter and 7 mm in length, which allowed its use in an array capable of hosting up to a 5 by 5 set of actuators with a rectangular shape covering an area of 18 mm by 21 mm. Using finite element analysis of several conceptual designs of actuators [1,4,5], it was established that the voice-coil type device (where the coil is the moving part) has most beneficial characteristics for the envisioned application. These include sufficient force over a relatively large distance, allowing tactile stimulation of surfaces with irregular shape, fast response, and small foot-print that matches the density of the tactile sensory neurons in the human finger. Eexperimental evaluation of the operation of neighboring actuators spaced at 3.3 mm apart, indicates that there is no crosstalk between the actuators. The resulting density exceeds that of previously reported alternative designs based on moveable permanent magnets [4,6]. Static force measurement indicate that each micro-actuator can produce at least 26 mN of repulsive force over a stroke of 2100 μm with a peak force of 34 mN. The driving circuit operates at 13.5V and generates a vibration frequency of up to 265 Hz without significant change of the force-displacement characteristics. In the higher frequency range (above 100 Hz) the actuator provides at least 15 mN of force over a slightly reduced stroke of 2300 μm, and a peak force of 21 mN. All of the above parameters meet the required threshold values of tactile human perception known from [2] and [3].