Optical tweezers (infrared laser-based optical traps) have emerged as a powerful tool in molecular and cell biology. However, their usefulness has been limited, particularly in vivo, by the potential for damage to specimens resulting from the trapping laser. Relatively little is known about the origin of this phenomenon. Here we employed a wavelength-tunable optical trap in which the microscope objective transmission was fully characterized throughout the near infrared, in conjunction with a sensitive, rotating bacterial cell assay. Single cells of Escherichia coli were tethered to a glass coverslip by means of a single flagellum: such cells rotate at rates proportional to their transmembrane proton potential (Manson et al.,1980. J. Mol. Biol. 138:541-561). Monitoring the rotation rates of cells subjected to laser illumination permits a rapid and quantitative measure of their metabolic state. Employing this assay, we characterized photodamage throughout the near-infrared region favored for optical trapping (790-1064 nm). The action spectrum for photodamage exhibits minima at 830 and 970 nm, and maxima at 870 and 930 nm. Damage was reduced to background levels under anaerobic conditions, implicating oxygen in the photodamage pathway. The intensity dependence for photodamage was linear, supporting a single-photon process. These findings may help guide the selection of lasers and experimental protocols best suited for optical trapping work.

The new Disability Attitudes in Health Care scale developed in this study shows good internal consistency and criterion validity. Attitudes toward caring for patients with disability seem to be unrelated to the standard medical education curriculum or previous experience with disability. Specific educational experiences may be designed to engender more positive attitudes toward providing health care to this patient population.

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Objective: To examine the psychometric properties of the Community Integration Questionnaire (CIQ) in large samples of individuals with spinal cord injury (SCI). Design: Longitudinal 12-month survey study. Setting: Nation-wide, community dwelling. Participants: Adults with SCI: 627 at Time 1, 494 at Time 2. Interventions: Not applicable. Outcome measures: The CIQ is a 15-item measure developed to measure three domains of community integration in individuals with traumatic brain injury: home integration, social integration, and productive activity. SCI consumer input suggested the need for two additional items assessing socializing at home and internet/email activity. Results: Exploratory factor analyses at Time 1 indicated three factors. Time 2 confirmatory factor analysis did not show a good fit of the 3-factor model. CIQ scores were normally distributed and only the Productive subscale demonstrated problems with high (25%) ceiling effects. Internal reliability was acceptable for the Total and Home scales, but low for the Social and Productive activity scales. Validity of the CIQ is suggested by significant differences by sex, age, and wheelchair use. Conclusions: The factor structure of the CIQ was not stable over time. The CIQ may be most useful for assessing home integration, as this is the subscale with the most scale stability and internal reliability. The CIQ may be improved for use in SCI by including items that reflect higher levels of productive functioning, integration across the life span, and home-and internet-based social functioning.

BackgroundMedical students have difficulty performing and interpreting musculoskeletal physical examinations and interpreting the findings. Research has focused on students' knowledge deficits, but there are few direct assessments of students' ability to perform a hypothesis-driven physical examination (HDPE). We developed a novel musculoskeletal Objective Structured Clinical Exam (OSCE) focusing on HDPE skills for disorders of the shoulder, back and knee, and used it to explore medical student diagnostic reasoning.MethodsA multidisciplinary group of musculoskeletal specialists developed and gathered validity evidence for a three station OSCE focusing on the HDPE of the shoulder, back and knee, emphasizing the ability to anticipate (identify pre-encounter) expected physical exam findings, and subsequently perform discriminatory physical examination maneuvers. The OSCE was administered to 45 final year medical students. Trained faculty observed and scored students’ ability to anticipate exam findings and perform diagnostic examination maneuvers on simulated patients. Encounters were digitally recorded and scored again by another trained faculty member. Inter-rater reliability for each maneuver was estimated using type-2 intra-class correlations (ICC). Percentages of perfect scores for anticipation and performance were calculated. Pearson’s correlation between anticipation and performance scores was computed for each maneuver and their relationship to diagnostic accuracy was tested with logistic regression.ResultsInter-rater reliability was good (ICC between .69 and .87) for six exam maneuvers. Maneuver performance was overall poor, with no discriminatory maneuver performed correctly by more than two thirds of students, and one maneuver only performed correctly by 4 % of students. For the shoulder and knee stations, students were able to anticipate necessary discriminatory exam findings better than they could actually perform relevant exam maneuvers. The ability to anticipate a discriminatory finding correlated with the ability to perform the associated maneuver correctly, with the exception of the ability to perform maneuvers needed to diagnose a torn anterior cruciate ligament of the knee. Neither the ability to anticipate or perform was predictive of identifying correct diagnoses for the different cases.ConclusionsA novel musculoskeletal OSCE, based on principles of the hypothesis-driven physical examination, was able to identify significant deficiencies in examination skills needed to diagnose common disorders of the shoulder, back and knee amongst graduating medical students. In addition, the OSCE demonstrated that accurate anticipation of discriminatory examination findings correlates with ability to perform the associated maneuver; however, the ability to anticipate exceeds the ability to perform. Students do not appear to be using the physical exam to inform their diagnostic reasoning. The findings of this study have implications for both assessment and teaching of the musculoskeletal exam.Electronic supple...