Responsiveness of a Balance Assessment Using a Mobile Application.

BACKGROUND: Balance assessment is used by clinicians as part of athlete concussion screening. The King-Devick (K-D) Balance app is designed to provide an objective balance assessment value. The purpose of this study was to investigate the responsiveness of a balance assessment using the K-D Balance app. HYPOTHESIS: The K-D Balance app will demonstrate acceptable responsiveness for balance assessment. STUDY DESIGN: Repeated-measures study. LEVEL OF EVIDENCE: Level 5. METHODS: A convenience sample of 25 participants between the ages of 20 and 25 years completed testing procedures. A battery of balance tests using the K-D Balance app on an iPhone were conducted 1 week apart. After a 5-minute warm-up, 3 stances were assessed: double leg, tandem right, and tandem left. The K-D Balance app guided the test positions and test times. A value representing movement was generated by the app algorithm. Analysis included descriptive statistics along with intraclass correlation coefficient and minimal detectable change (MDC). RESULTS: The median score of the K-D test was 0.5 for session 1 and 0.4 for session 2. The ICC was 0.42 (95% CI, 0.04-0.70), and the MDC was 1.58. CONCLUSION: The MDC value of 1.58 represents the threshold of meaningful change in balance, as measured with the K-D Balance app. CLINICAL RELEVANCE: Clinicians can use the results of this study to objectively assess changes in balance over time using the K-D Balance app.

A stable bioluminescent construct of Escherichia coli O157:H7 for hazard assessments of long-term survival in the environment.

A chromosomally lux-marked (Tn5 luxCDABE) strain of nontoxigenic Escherichia coli O157:H7 was constructed by transposon mutagenesis and shown to have retained the O157, H7, and intimin phenotypes. The survival characteristics of this strain in the experiments performed (soil at -5, -100, and -1,500 kPa matric potential and artificial groundwater) were indistinguishable from the wild-type strain. Evaluation of potential luminescence was found to be a rapid, cheap, and quantitative measure of viable E. coli O157:H7 Tn5 luxCDABE populations in environmental samples. In the survival studies, bioluminescence of the starved populations of E. coli O157:H7 Tn5 luxCDABE could be reactivated to the original levels of light emission, suggesting that these populations remain viable and potentially infective to humans. The attributes of the construct offer a cheap and low-risk substitute to the use of verocytotoxin-producing E. coli O157:H7 in long-term survival studies.