Structural validity of the Trunk Assessment Scale for Spinal Cord Injury (TASS) with Rasch analysis for individuals with spinal cord disorders.

OBJECTIVE: To confirm the structural validity of the Trunk Assessment Scale for Spinal Cord Injury (TASS). PARTICIPANTS AND METHODS: We evaluated 104 Japanese individuals with a spinal cord injury (SCI) (age 63.5 ± 12.2 years; 64 with tetraplegia) with the TASS 1-3 times. We conducted a Rasch analysis to assess the TASS' unidimensionality, fit statistics, category probability curve, ceiling/floor effects, local independence, reliability, and difference item function (DIF). RESULTS: The TASS was observed to be a unidimensional and highly reproducible scale of item difficulty hierarchy that sufficiently identifies the superiority of the examinee's ability. The TASS was easy for the participants of this study. One TASS item was a misfit based on the infit and outfit mean square; another item also showed a DIF contrast for age. Several items were found to require a synthesis or modification of the content. The TASS showed a floor effect, and most of the non-scorers were individuals with a complete SCI. CONCLUSION: Our findings clarify the structural validity of the TASS, and our analyses revealed that the TASS includes an unfitness item and was less challenging for individuals with SCIs. The improvements suggested by these results provide important information for modifying the TASS to a more useful instrument.

Validity of the trunk assessment scale for spinal cord injury (TASS) and the trunk control test in individuals with spinal cord injury.

BACKGROUND: The Trunk Assessment Scale for Spinal Cord Injury (TASS) and the Trunk Control Test for individuals with a Spinal Cord Injury (TCT-SCI) are highly reliable assessment tools for evaluating the trunk function of individuals with SCIs. However, the potential differences in the validity of these two scales are unclear. OBJECTIVES: To evaluate the criterion validity of the TASS and the construct validity of the TASS and TCT-SCI. PARTICIPANTS AND METHODS: We evaluated 30 individuals with SCIs (age 63.8 ± 10.7 yrs, 17 with tetraplegia). To evaluate criterion validity, we calculated Spearman's rho between the TASS and the gold standard (the TCT-SCI). To determine construct validity, we used the following hypothesis testing approaches: (i) calculating Spearman's rho between each scale and the upper and lower extremity motor scores (UEMS, LEMS), the Walking Index for SCI-II (WISCI-II), and the motor score of the Functional Independence Measure (mFIM); and (ii) determining the cut-off point for identifying ambulators with SCIs (≥ 3 points on item 12 of Spinal Cord Independent Measure III) by a receiver operating characteristics analysis. RESULTS: A moderate correlation was confirmed between the TASS and the TCT-SCI (r = 0.68). Construct validity was supported by six of the eight prior hypotheses. The cut-off points for identifying ambulators with SCIs were 26 points (TASS) and 18 points (TCT-SCI). CONCLUSION: Our results indicate that the contents of the TASS and the TCT-SCI might reflect the epidemiological characteristics of the populations in which they were developed.

Responsiveness and minimal clinically important differences of the Trunk Assessment Scale for Spinal Cord injury (TASS).

OBJECTIVE: To confirm the responsiveness and minimal clinically important differences (MCIDs) of the Trunk Assessment Scale for Spinal Cord Injury (TASS). PARTICIPANTS AND METHODS: We evaluated 48 Japanese individuals with spinal cord injury (SCI) (age 64.1 ± 10.4 yrs, 28 with tetraplegia) admitted to two institutions at admission, at 1 month of hospitalization, and at discharge with the TASS, the Trunk Control Test in individuals with an SCI (TCT-SCI) motor score, the Functional Independence Measure motor score (mFIM), and the Global Rating of Change Scale (GRCS). We assessed the TASS responsiveness by determining the correlation coefficients for the changes in the TASS' and other assessments' scores. We calculated the MCIDs by five anchor-based methods. RESULTS: The changes in the TASS and those in the other assessments were weakly correlated at 1 month and moderately correlated at discharge. The TASS MCIDs were observed at 1 month and at discharge. CONCLUSION: Our findings confirmed that the change in TASS scores had weak-to-moderate correlations with the changes in the participants' upper- and lower-limb function and activities of daily living. Using the MCID for the TASS determined by anchor-based methods may lead to a better interpretation of changes in the trunk function of individuals with SCIs.

Reliability and minimal detectable change of the Trunk Assessment Scale for Spinal Cord Injury (TASS) and the trunk control test for individuals with spinal cord injury.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To evaluate the reliability and calculate the measurement error of the Trunk Assessment Scale for Spinal Cord Injury (TASS) and trunk control test (TCT-SCI) in individuals with spinal cord injury (SCI). SETTING: Rehabilitation Hospital in Japan. METHODS: The evaluations of TASS and TCT-SCI for individuals with SCI were video-recorded. The inter-rater reliability (two physiotherapists) was confirmed using the videos. ICC (2,1), kappa coefficient (κ) were used to determine the reliability of the total score and each item. Each minimal detectable change (MDC) was calculated. RESULTS: The TASS and TCT-SCI total scores showed excellent inter-rater reliability (ICC = 0.99, and 1.00). The kappa coefficients of TASS were acceptable to excellent for 8 items (κ = 0.76-1.00), below acceptable for 1 item (κ = 0.62). The kappa coefficients of TCT-SCI were excellent for 12 items (κ = 0.83-1.00), below acceptable for 1 item (κ = 0.68). The inter-rater MDC of the TASS total score was 4.07 points, and the MDC of the TCT-SCI total score was 1.13 points. The intra-rater MDC of the TASS total score was 3.86 points. CONCLUSION: Both TASS and TCT-SCI showed high reliability. Differences of less than four points in TASS and one point in TCT-SCI were interpreted as measurement errors between the two raters.

A single-molecule assessment of the protective effect of DMSO against DNA double-strand breaks induced by photo-and γ-ray-irradiation, and freezing.

Dimethyl sulfoxide (DMSO) is widely used as a cryoprotectant for organs, tissues, and cell suspension in storage. In addition, DMSO is known to be a useful free radical scavenger and a radio-protectant. To date, many in vitro assays using cultured cells have been performed for analysing the protective effect of DMSO against genomic DNA damage; however, currently it has been rather difficult to detect DNA double strand breaks (DSBs) in a quantitative manner. In the present study, we aimed to observe the extent of DNA damage by use of single molecular observation with a fluorescence microscope to evaluate DSBs induced by photo- and γ-ray-irradiation, or freeze/thawing in variable concentrations of DMSO. As a result, we found that 2% DMSO conferred the maximum protective effect against all of the injury sources tested, and these effects were maintained at higher concentrations. Further, DMSO showed a significantly higher protective effect against freezing-induced damage than against photo- and γ-ray-irradiation-induced damage. Our study provides significant data for the optimization of DNA cryopreservation with DMSO, as well as for the usage of DNA as the protective agent against the injuries caused by active oxygen and radiations.

Marked difference in conformational fluctuation between giant DNA molecules in circular and linear forms.

We performed monomolecular observations on linear and circular giant DNAs (208 kbp) in an aqueous solution by the use of fluorescence microscopy. The results showed that the degree of conformational fluctuation in circular DNA was ca. 40% less than that in linear DNA, although the long-axis length of circular DNA was only 10% smaller than that of linear DNA. Additionally, the relaxation time of a circular chain was shorter than that of a linear chain by at least one order of magnitude. The essential features of this marked difference between linear and circular DNAs were reproduced by numerical simulations on a ribbon-like macromolecule as a coarse-grained model of a long semiflexible, double-helical DNA molecule. In addition, we calculated the radius of gyration of an interacting chain in a circular form on the basis of the mean field model, which provides a better understanding of the present experimental trend than a traditional theoretical equation.

A toy model for nucleus-sized crowding confinement.

We conduct Monte Carlo simulations to understand the spatial distribution of a polymer molecule confined within a rigid spherical capsule under crowding conditions, via a bead-spring chain model. To adjust the crowding level, the polymer is mixed with spherical crowders. As the interior of the capsule becomes more crowded, chain monomers tend to move to the capsule boundary under the penalty of conformational entropy. By incorporating some attraction between monomers and crowders, the polymer chain moves away from the capsule boundary. The interplay, between the conformational entropy, DNA-protein interaction, and molecular crowding induced depletion force between the chain and capsule boundary, may be essential to elucidate the heterogeneous chromatin structure in nuclei. Furthermore, the effects of chain length and size disparity between the monomers and the crowders are also investigated preliminarily.

Rigidity of a spherical capsule switches the localization of encapsulated particles between inner and peripheral regions under crowding condition: simple model on cellular architecture.

We have investigated the inhomogeneous interior of confined spherical cavities as capsules containing encapsulated binary hard sphere mixtures for different compositions and cavity wall rigidity. Such a greatly simplified model manifests the effects of macromolecular crowding arising from excluded volume interactions in a tiny cell or a cellular nucleus. By fixing the number of large particles, the level of crowding is adjusted by changing the amount of small hard spheres in the cavity. For a rigid cavity, large spheres tend to pack in liquid-like order apart from the surface to the center of the cavity as the crowding level is increased. Whereas, for a soft cavity, larger spheres tend to blend with small spheres in the peripheral region at near the boundary of the cavity, and are susceptible to be depleted from the interior of the cavity as the cavity becomes more crowded. These results may help future elucidation of the thermodynamic pathways to stabilize the inhomogeneous structure of mixtures confined in cavities, such as the derepression of genome materials around the interior rim of the nucleus in a cancerous cell.

Confinement causes opposite effects on the folding transition of a single polymer chain depending on its stiffness.

We investigated the folding transition between an elongated coil state and a compact state on a single polymer chain confined in a small space with different stiffness with the aid of Monte Carlo simulation. In a flexible polymer, the folding transition is retarded in a confined space. In contrast, the transition is promoted for a semiflexible chain, in which the discontinuity of the volume change occupied by a single chain is diminished by confinement. This unique confinement effect is interpreted in terms of conformational entropy and self-avoiding repulsive interaction.

Elucidation of conformational hysteresis on a giant DNA.

The conformational behavior of a giant DNA mediated by condensing agents in the bulk solution has been investigated through experimental and theoretical approaches. Experimentally, a pronounced conformational hysteresis is observed for folding and unfolding processes, by increasing and decreasing the concentration of condensing agent (polyethylene glycol) (PEG), respectively. To elucidate the observed hysteresis, a semiflexible chain model is studied by using Monte Carlo simulations for the coil-globule transition. In the simulations, the hysteresis loop emerges for stiff enough chains, indicating distinct pathways for folding and unfolding processes. Also, our results show that globular state is thermodynamically more stable than coiled state in the hysteresis loop. Our findings suggest that increasing chain stiffness may reduce the chain conformations relevant to the folding pathway, which impedes the folding process.

Competition between compaction of single chains and bundling of multiple chains in giant DNA molecules.

It has been established that in a dilute solution individual giant DNA molecules undergo a large discrete transition between an elongated coil state and a folded compact state. On the other hand, in concentrated solutions, DNA molecules assemble into various characteristic states, including multichain aggregate, liquid crystalline, ionic crystal, etc. In this study, we compared single-chain and multiple-chain events by observing individual chains using fluorescence microscopy. We used spermidine, SPD(3+), as a condensing agent for giant DNA. When the concentration of DNA is below 1 microM in base-pair units, individual DNA molecules exhibit a transition from an elongated state to a compact state. When the concentration of DNA is increased to 10 microM, a thick fiberlike assembly of multiple chains appears. AFM measurements of this thick fiber revealed that more than tens of DNA molecules form a bundle structure with parallel ordering of the chains. The transition between single-chain compaction and bundle formation with multiple-chain assemblies was reproduced by a theoretical calculation.