Disease activity and dropout in young persons with juvenile idiopathic arthritis in transition of care: a longitudinal observational study.

OBJECTIVES: Reaching a certain age, juvenile idiopathic arthritis (JIA) patients in paediatric care are transferred to adult care. An increased disease activity after transfer and increased dropout has been suggested, however, evidence is scarce. Our aim is to determine whether the process of transition is associated with increased disease-activity and dropout, and to identify associated factors. METHODS: During a 3-year prospective transition cohort study, paediatric patients (14-17yrs) were transferred to adult care. Paediatric (10-13yrs) and adult JIA patients (18-27yrs) were used as control groups. Demographic and disease-related items were obtained yearly. Non-parametric tests were used to compare differences between the groups and mixed models to evaluate disease activity over time, measured by JADAS27 and DAS28. Dropout was defined as not attending the clinic for 2 consecutive visits. RESULTS: Groups did not differ regarding baseline variables of subtype, gender, uveitis, ANA-, RF- or HLA B27-positivity and current or past DMARD use. Median disease activity was not different between groups during follow-up. Transfer was not associated with disease activity. Dropout rate was 12%, and was significantly higher in patients under transition (22%) compared with paediatric (3%) and adult care (10%). Patients who dropped out had significantly lower disease activity at baseline and were using less MTX, but did not differ regarding subtype, ANA, RF and HLA-B27. CONCLUSIONS: The process of transition in JIA is not associated with an increase in disease activity, however, this period carries a risk for drop out especially in patients with low disease activity.

An implantable RF solenoid for magnetic resonance microscopy and microspectroscopy.

Miniature solenoids routinely enhance small volume nuclear magnetic resonance imaging and spectroscopy; however, no such techniques exist for patients. We present an implantable microcoil for diverse clinical applications, with a microliter coil volume. The design is loosely based on implantable depth electrodes, in which a flexible tube serves as the substrate, and a metal stylet is inserted into the tube during implantation. The goal is to provide enhanced signal-to-noise ratio (SNR) of structures that are not easily accessed by surface coils. The first-generation prototype was designed for implantation up to 2 cm, and provided initial proof-of-concept for microscopy. Subsequently, we optimized the design to minimize the influence of lead inductances, and to thereby double the length of the implantable depth (4 cm). The second-generation design represents an estimated SNR improvement of over 30% as compared to the original design when extended to 4 cm. Impedance measurements indicate that the device is stable for up to 24 h in body temperature saline. We evaluated the SNR and MR-related heating of the device at 3T. The implantable microcoil can differentiate fat and water peaks, and resolve submillimeter features.

A low-power, low-noise neural-signal amplifier circuit in 90-nm CMOS.

A fully-differential low-power low-noise preamplifier for biopotential and neural-recording applications is presented. This design, which has been simulated in a standard 90-nm CMOS process, consumes 30 microW from a 3-V power supply. The simulated integrated input-referred noise is 2.3 microV over 0.1 Hz to 20 kHz. The amplifier also provides an output swing of +/- 0.9 V with a THD of less than 0.1%

A linear piezoelectric stepper motor with submicrometer step size and centimeter travel range.

A linear stepper motor capable of submicrometer controlled movement has been constructed using the piezoelectric material lead zirconate titanate (PZT). This motor consists of a 25.4-mmx12.7-mmx1.6-mm piezoelectric driving element connected between a glider base and an attached load. The device is inset in a trench to constrain motion to one dimension. An electrode on the bottom of the glider is used with an electrode on the top of the trench to implement an electrostatic clamp. This clamp enables the stepper motor to climb slopes of up to 12 degrees , whereas without the clamp only slopes of 6 degrees or less are tolerated. A linear inertial sliding motion can be achieved by expanding and contracting the piezoelectric bar, but the addition of the electrostatic clamp enhances the movement capabilities of the glider by the periodic clamping and unclamping of the glider. Glider velocities of 5.7-476 mum/s are measured by timing the movement of the glider over a 1.0-mm portion of the track through an optical microscope. Displacement steps of 0.07-1.1 mum are calculated by dividing the measured glider velocity by the frequency of the applied voltage pulses. Displacement step size and glider velocity are controlled by the application of PZT extension voltages ranging from +/-(60-340) V.