The critical sensor: a new type of evanescent wave immunosensor

A new planar waveguide immunosensor has been developed in which adsorption at a surface, changing the refractive index contrast, is measured. In this ¿critical¿ sensor the change in the effective refractive index contrast is transducted to a shift of the critical reflection angle. The sensor's response after a specific binding of antigens to antibodies is discussed theoretically. In addition, an experimental sensitivity evaluation on the basis of several immunosensing experiments is presented. The obtained lower detection limit is 2 × 10¿2 nm in adlayer growth, equivalent to 12 pg/mm2 of analyte coverage. This sensitivity is comparable to the performance of the surface plasmon resonance sensors or the grating coupler sensors. However, the ¿critical¿ sensor has some advantages. These are mainly the ease of fabrication and adjustment prior to a measurement, and the fact for an experiment no metal layer has to be used

New detection method for atrazine pesticides with the optical waveguide Mach-Zehnder immunosensor

Concentrations of analytes can be determined within a few minutes using on-line analysis of the immunobinding kinetics in a solid phase immunoassay. This approach has been applied to the detection of atrazine. Atrazine is detected, at concentrations around the European Community limit (0.1 ¿g/l) by a competitive assay. To this end, the two channels of a Mach-Zehnder waveguide sensor are used simultaneously in a difference measurement. The advantage of this way of measuring is discussed with the atrazine measurements

Optical-trapping micromanipulation using 780-nm diode lasers

We have designed and implemented an optical-trapping configuration that uses near-infrared laser diodes. The highly divergent output beam of the diode laser was collimated by using only one aspheric compact disc lens. The resulting output beams are astigmatic and elliptic and have a flat, non-Gaussian intensity profile. Calculations and measurements were performed to investigate the influence of this profile on the trapping forces. The results show that use of a laser diode, collimated with a compact disc lens, provides a near-infrared light source that can be used for optical trapping. The light source is compact and relatively cheap and can be easily incorporated into an existing microscope

The realization of an integrated Mach-Zehnder waveguide immunosensor in silicon technology

We describe the realization of a symmetric integrated channel waveguide Mach-Zehnder sensor which uses the evanescent field to detect small refractive-index changes (¿nmin ¿ 1 × 10¿4) near the guiding-layer surface. This guiding layer consists of ridge structures with a height of 3 nm and a width of 4 ¿m made in Si3N4. This layer has a thickness of 100 nm. The sensor device has been tested with glucose solutions of different bulk refractive indices. Results of a slab-model calculation are in good agreement with obtained experimental results. The feasibility of applying this sensor for immunosensing, detecting directly the binding of antigen to an antibody receptor surface, is shown with antibody-antigen binding experiments

Prevalence rate, predictors and long-term course of probable posttraumatic stress disorder after major trauma: A prospective cohort study

Background: Among trauma patients relatively high prevalence rates of posttraumatic stress disorder (PTSD) have been found. To identify opportunities for prevention and early treatment, predictors and course of PTSD need to be investigated. Long-term follow-up studies of injury patients may help gain more insight into the course of PTSD and subgroups at risk for PTSD. The aim of our long-term prospective cohort study was to assess the prevalence rate and predictors, including pre-hospital trauma care (assistance of physician staffed Emergency Medical Services (EMS) at the scene of the accident), of probable PTSD in a sample of major trauma patients at one and two years after injury. The second aim was to assess the long-term course of probable PTSD following injury.Methods: A prospective cohort study was conducted of 332 major trauma patients with an Injury Severity Score (ISS) of 16 or higher. We used data from the hospital trauma registry and self-assessment surveys that included the Impact of Event Scale (IES) to measure probable PTSD symptoms. An IES-score of 35 or higher was used as indication for the presence of probable PTSD.Results: One year after injury measurements of 226 major trauma patients were obtained (response rate 68%). Of these patients 23% had an IES-score of 35 or higher, indicating probable PTSD. At two years after trauma the prevalence rate of probable PTSD was 20%. Female gender and co-morbid disease were strong predictors of probable PTSD one year followin

Voorspellende factoren van functionele beperkingen na ernstig letsel

OBJECTIVE: To assess the health-related quality of life and prognostic factors of disability in survivors of severe trauma one year after injury. DESIGN:Prospective cohort study. METHOD: All severely-injured trauma patients presenting at a level I trauma centre during a 30-month period and surviving 30 days after admission were included. The EuroQol-5D (EQ-5D) and Health Utilities Index (HUI) were used to determine the health status 12 months after injury. RESULTS: 362 patients were included during the study period, 246 of whom returned the follow-up assessments (response rate: 68%). The median EQ-5D utility score was 0.73 (EQ-5D Dutch general population norm: 0.88). The HUI2, HUI3 and EQ-5D Visual Analogue Scale scores were 0.81, 0.65 and 70, respectively. One year after trauma only 22% of the patients reported no functional limitation in the 5 domains of the EQ-D5. Females and patients with co-morbidity at the time of the injury had a higher risk of low scores after 1 year. CONCLUSION: One year after severe injury, the functional outcome and quality of life of trauma patients were far from normalized. Female gender and comorbidity were predictors of poorer functional outcome

Willingness to pay for lives saved by helicopter emergency medical services

Introduction. Currently, policy makers in the Netherlands are discussing the possibility to expand the availability of Helicopter Emergency Medical Services (HEMS) from 12 hours to 24 hours per day. For this, the preferences of the general public towards both the positive effects and negative consequences of HEMS should be taken into account. Therefore, the willingness to pay (WTP) for lives saved by HEMS was calculated. Methods. A discrete choice experiment (DCE) was performed in order to explore the preferences of respondents towards (expansion of) HEMS availability. The attributes: costs (for HEMS) per household number of additional lives saved (by HEMS), number of noise disturbances (caused by HEMS) during day time or night time were used. A written questionnaire was presented to 150 individuals by convenience sampling. Result. One hundred and thirty-six (91%) of the 150 individuals completed the DCE questionnaire. The marginal WTP for one additional life saved (in a month) was 3.43 (95% CI; 2.96-3.90) per month per household. Overall, the WTP for expansion to a 24-hour availability of HEMS can therefore be estimated at 12.29 (∼ US$ 17.50) per household per month. Conclusion. The WTP derived from this study is by far exceeding the 1-1.5 Million-euro necessary per HEMS per year for the expansion from a daytime HEMS to a 24-h availability in the Netherlands. Respondents are willing to pay for lives saved by HEMS in spite of increases in flights and concurrent noise disturbances. These results may be helpful for the decision-making process,

Early mobilisation versus plaster immobilisation of simple elbow dislocations: Results of the FuncSiE multicentre randomised clinical trial

Background/aim To compare outcome of early mobilisation and plaster immobilisation in patients with a simple elbow dislocation. We hypothesised that early mobilisation would result in earlier functional recovery. Methods From August 2009 to September 2012, 100 adult patients with a simple elbow dislocation were enrolled in this multicentre randomised controlled trial. Patients were randomised to early mobilisation (n=48) or 3 weeks plaster immobilisation (n=52). Primary outcome measure was the Quick Disabilities of the Arm, Shoulder, and Hand (Quick-DASH) score. Secondary outcomes were the Oxford Elbow Score, Mayo Elbow Performance Index, pain, range of motion, complications and activity resumption. Patients were followed for 1 year. Results Quick-DASH scores at 1 year were 4.0 (95% CI 0.9 to 7.1) points in the early mobilisation group versus 4.2 (95% CI 1.2 to 7.2) in the plaster immobilisation group. At 6 weeks, early mobilised patients reported less disability (Quick-DASH 12 (95% CI 9 to 15) points vs 19 (95% CI 16 to 22); p<0.05) and had a larger arc of flexion and extension (121° (95% CI 115° to 127°) vs 102° (95% CI 96° to 108°); p<0.05). Patients returned to work sooner after early mobilisation (10 vs 18 days; p=0.020). Complications occurred in 12 patients; this was unrelated to treatment. No recurrent dislocations occurred. Conclusions Early active mobilisation is a safe and effective treatment for simple elbow dislocations. Patients recovered faster and returned to work earlier without increasing the complication rate. No evidence was found supporting treatment benefit at 1 year