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Digital game-based learning (DGBL) environments are increasingly utilized to facilitate classroom instruction. For the game in our study, a formative stealth assessment tool, in the form of an intelligent tutoring system (ITS) is guided by evidence-centered assessment design (ECD). Cognitive Load Theory and ECD are utilized as diagnostic tools to analyze upsurges in hints delivered by the ITS and inform game design revisions that will promote improved learner support and learning outcomes.

Secreted Frizzled-related protein-1 (sFRP-1) contains a cysteine-rich domain homologous to the putative Wnt-binding site of Frizzleds. To facilitate the biochemical and biological analysis of sFRP-1, we developed a mammalian recombinant expression system that yields ∼3 mg of purified protein/liter of conditioned medium. Using this recombinant protein, we demonstrated that sFRP-1 and Wg (wingless) interact in enzyme-linked immunosorbent and co-precipitation assays. Surprisingly, a derivative lacking the cysteine-rich domain retained the ability to bind Wg. Cross-linking experiments performed with radioiodinated sFRP-1 provided definitive evidence that sFRP-1 and Wg bind directly to each other. Besides detecting a cross-linked complex consistent in size with 1:1 stoichiometry of sFRP-1 and Wg, we also observed a larger complex whose size suggested the presence of a second sFRP-1 molecule. The formation of both complexes was markedly enhanced by an optimal concentration of exogenous heparin, emphasizing the potential importance of heparan-sulfate proteoglycan in Wnt binding and signaling. sFRP-1 exerted a biphasic effect on Wg activity in an armadillo stabilization assay, increasing armadillo level at low concentrations but reducing it at higher concentrations. These results provide new insights about the Wnt binding and biological activity of sFRPs.

This study characterized changes in the protein composition of human muscle tissue after eccentric exercise. Four subjects performed 70 maximum eccentric, isokinetic actions of the forearm flexors with one arm. The other arm served as control. A biopsy of the biceps muscle of each arm was taken 2 days after exercise when muscles were very sore (mean = 8.0; 1 = normal; 10 = very, very sore), and muscle damage was documented by a mean decrease of 0.2 radians in the relaxed elbow angle. Proteins from the biopsy tissue were solubilized in a high ionic strength buffer containing several proteolytic inhibitors. Protein concentrations of the extracts were determined and identical amounts loaded onto sodium dodecyl sulfate (SIDS) polyacrylamide gels (7.5, 12.5, and 17.5%). Densitometric analysis of the Coomassie brilliant blue stained gels revealed alterations in the amounts of three protein bands in the exercised tissue relative to the control. These changes were in the linear portion of the graph of absorbance versus protein amount. Wilcoxon's signed rank test showed the first two of the following bands to increase significantly in amount (P < 0.062). The average percentage changes [mean (SEM)] for these bands were 63 (21), 39 (5), and 82 (35). The corresponding molecular weights determined from known standards were 76 300 (860), 33 200 (310), and 12 000 (80) daltons, respectively. These changes imply that the increased synthesis, decreased degradation, or some combination thereof, of these three proteins may be necessary for the repair or regeneration response to exercise-induced muscle damage.

Running kinematics and physiological responses to high intensity submaximal treadmill running in training shoes and racing flats were evaluated. Eight women (mean age = 21.9 yr) completed a peak O2test on the treadmill (mean peak O2= 49.2 ml·kg-1·min-1). In two subsequent testing sessions, subjects completed 15-min runs at a speed corresponding to 90 of peak O2(range = 9.9–13.4 km·hr-1) while wearing training shoes and racing flats (balanced order assignment). No significant time effect or time by shoe condition interaction was observed for the rearfoot motion variables. Maximum rearfoot angle and total rearfoot motion averaged 42 and 13.9 higher, respectively, for the racing flat (P< 0.05). There were significant increases over time for O2, E, HR, and RPE, indicating an increase in cardiorespiratory response and the perception of effort over the course of the 15-min run. Thus, metabolic and perceptual indications of fatigue at the end of the run emerged but were not accompanied by rearfoot motion changes in either running shoe. These results indicate that rearfoot motion is a function of shoe design and did not change during 15 min of high intensity running.