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Nucleic acid based affinity reagents (e.g., aptamers) offer several possible advantages over antibodies as specific recognition elements in biochemical assays. Besides offering improved cost and stability, aptamers are ideal for rapid electrophoretic analysis due to their low molecular weight and high negative charge. While aptamers have proven well-suited for affinity-shift electrophoretic analysis, demonstrating a fully integrated aptamer-based assay platform represents an important achievement toward low-cost point-of-care analysis, particularly for remote or resource poor settings where cost and ambient stability of reagents is a key consideration. Here we perform and evaluate the suitability of aptamer-based affinity assays for two clinically relevant target analytes (IgE using a known aptamer and NF-[kappa]B using a thio-modified aptamer) in an integrated electrophoretic gel-shift platform. Key steps of (i) mixing sample with aptamer, (ii) buffer exchange, and (iii) preconcentration of sample were successfully integrated on-chip upstream of a fluorescence-based gel-shift analysis step. This approach, utilizing a size-exclusion membrane optimized here for aptamer retention and preconcentration with sample, enables automated sample-to-answer for trace analytes in 10 rain or less. We addressed notable nonspecific interference from serum proteins by adding similar nucleic acid competitors to suppress such interactions with the aptamer. Nanomolar sensitivities were demonstrated and integrated preconcentration of sample provides an important means of further improving detection sensitivities. Aptamers proved superior in many respects to antibody reagents, particularly with regard to speed and resolution of gel-shifts associated with specific binding to target. 10.1021/ac101106

Lightweight ambulatory oxygen devices are provided on the assumptions that they enhance compliance and increase activity, but data to support these assumptions are lacking. We studied 22 patients with severe chronic obstructive pulmonary disease receiving long-term oxygen therapy (14 men, average age == 66.9 y, FEV1 == 33.6%%pred, PaO2 at rest == 51.7 torr) who were using E-cylinders as their portable oxygen. Subjects were recruited at 5 sites and studied over a 2-week baseline period and for 6 months after randomizing them to either continuing to use 22-lb E-cylinders towed on a cart or to carrying 3.6-lb aluminum cylinders. Utilizing novel electronic devices, ambulatory and stationary oxygen use was monitored continuously over the 2 weeks prior to and the 6 months following randomization. Subjects wore tri-axial accelerometers to monitor physical activity during waking hours for 2-3 weeks prior to, and at 3 and 6 months after, randomization. Seventeen subjects completed the study. At baseline, subjects used 17.2 hours of stationary and 2.5 hours of ambulatory oxygen daily. At 6 months, ambulatory oxygen use was 1.4 ± 1.0 hrs in those randomized to E-cylinders and 1.9 ± 2.4 hrs in those using lightweight oxygen (P == NS). Activity monitoring revealed low activity levels prior to randomization and no significant increase over time in either group. In this group of severe chronic obstructive pulmonary disease patients, providing lightweight ambulatory oxygen did not increase either oxygen use or activity. Future efforts might focus on strategies to encourage oxygen use and enhance activity in this patient group. This trial is registered at ClinicalTrials.gov (NCT003257540). [ABSTRACT FROM AUTHOR]

We sought to develop procedures for computerized analysis of long-term, high-resolution activity monitoring data that allow accurate assessment of the time course of activity levels suitable for use in chronic obstructive pulmonary disease (COPD) patients. Twenty-two COPD patients utilizing long-term oxygen recruited from 5 sites of the COPD Clinical Research Network wore a triaxial accelerometer (RT3, Stayhealthy, Monrovia, CA) during waking hours over a 14-day period. Computerized algorithms were composed allowing minute-by-minute activity data to be analyzed to determine, for each minute, whether the monitor was being worn. Temporal alignment allowed determination of average time course of activity level, expressed as average vector magnitude units (VMU, the vectorial sum of activity counts in three orthogonal directions) per minute, for each hour of the day. Mid-day activity was quantified as average VMU/minute between 10AM and 4PM for minutes the monitor was worn. Over the 14 day monitoring period, subjects wore the monitor an average of 11.4 ± 3.0 hours·day- 1. During mid-day hours, subjects wore the monitor 76.3% of the time and generated an average activity level of 112 ± 55 VMU·min-1. Increase in precision of activity estimates with longer monitoring periods was demonstrated. This analysis scheme allows a detailed temporal pattern of activity to be defined from triaxial accelerometer recordings and has the potential to facilitate comparisons among subjects and between subject groups. This trial is registered at ClinicalTrials.gov (NCT00325754). [ABSTRACT FROM AUTHOR]