Hamstring harvest results in significantly reduced knee muscular protection during side-step cutting two years after anterior cruciate ligament reconstruction

The purpose of this study was to determine the effect of donor muscle morphology following tendon harvest in anterior cruciate ligament (ACL) reconstruction on muscular support of the tibiofemoral joint during sidestep cutting. Magnetic resonance imaging (MRI) was used to measure peak cross-sectional area (CSA) and volume of the semitendinosus (ST) and gracilis (GR) muscles and tendons (bilaterally) in 18 individuals following ACL reconstruction. Participants performed sidestep cutting tasks in a biomechanics laboratory during which lower-limb electromyography, ground reaction loads, whole-body motions were recorded. An EMG driven neuro-musculoskeletal model was subsequently used to determine force from 34 musculotendinous units of the lower limb and the contribution of the ST and GR to muscular support of the tibiofemoral joint based on a normal muscle-tendon model (Standard model). Then, differences in peak CSA and volume between the ipsilateral/contralateral ST and GR were used to adjust their muscle-tendon parameters in the model followed by a recalibration to determine muscle force for 34 musculotendinous units (Adjusted model). The combined contribution of the donor muscles to muscular support about the medial and lateral compartments were reduced by 52% and 42%, respectively, in the adjusted compared to standard model. While the semimembranosus (SM) increased its contribution to muscular stabilisation about the medial and lateral compartment by 23% and 30%, respectively. This computer simulation study demonstrated the muscles harvested for ACL reconstruction reduced their support of the tibiofemoral joint during sidestep cutting, while the SM may have the potential to partially offset these reductions. This suggests donor muscle impairment could be a factor that contributes to ipsilateral re-injury rates to the ACL following return to sport.

DUF2285 is a novel helix-turn-helix domain variant that orchestrates both activation and antiactivation of conjugative element transfer in proteobacteria

Horizontal gene transfer is tightly regulated in bacteria. Often only a fraction of cells become donors even when regulation of horizontal transfer is coordinated at the cell population level by quorum sensing. Here, we reveal the widespread 'domain of unknown function' DUF2285 represents an 'extended-turn' variant of the helix-turn-helix domain that participates in both transcriptional activation and antiactivation to initiate or inhibit horizontal gene transfer. Transfer of the integrative and conjugative element ICEMlSymR7A is controlled by the DUF2285-containing transcriptional activator FseA. One side of the DUF2285 domain of FseA has a positively charged surface which is required for DNA binding, while the opposite side makes critical interdomain contacts with the N-terminal FseA DUF6499 domain. The QseM protein is an antiactivator of FseA and is composed of a DUF2285 domain with a negative surface charge. While QseM lacks the DUF6499 domain, it can bind the FseA DUF6499 domain and prevent transcriptional activation by FseA. DUF2285-domain proteins are encoded on mobile elements throughout the proteobacteria, suggesting regulation of gene transfer by DUF2285 domains is a widespread phenomenon. These findings provide a striking example of how antagonistic domain paralogues have evolved to provide robust molecular control over the initiation of horizontal gene transfer.

Choosing to avoid the positive? Emotion regulation strategy choice in depression

Individuals with major depressive disorder (MDD) are more likely than nondepressed individuals to use emotion regulation strategies that decrease pleasant emotions (e.g., distraction from positive stimuli) and increase unpleasant emotions (e.g., negative rumination). If such strategies are actively chosen, these choices may partly reflect weaker motivation for pleasant emotions or stronger motivation for unpleasant emotions. Therefore, this investigation tested, for the first time, whether such strategies are actively chosen, even when alternatives are available. In Study 1, using a behavioral task, MDD participants (N = 38) were more likely than healthy controls (N = 39) to choose to use distraction over positive rumination in response to pleasant stimuli, resulting in reductions in pleasant affect. When instructed to choose the strategy that would make them feel better, however, MDD participants did not differ from controls in their strategy choices. In Study 2, using ecological momentary assessments, MDD participants (N = 58) were more likely than controls (N = 62) to use distraction from pleasant emotions and to use negative rumination in daily life. This pattern of strategy use was predicted by stronger motivation for unpleasant emotions among MDD participants, compared to controls. Stronger motivation for unpleasant emotions in daily life also predicted increases in unpleasant affect and decreases in pleasant affect. Findings suggest that compared to nondepressed individuals, people with MDD are more likely to choose emotion regulation strategies that decrease pleasant emotions. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Measuring college belongingness: Structure and measurement of the Sense of Social Fit Scale

Sense of belonging is theorized to be a fundamental human need and has been shown to have important implications in many domains of life, including academic achievement. The Sense of Social Fit scale (SSF; Walton & Cohen, 2007) is widely used to assess college belongingness, particularly to study differences in academic experiences along lines of gender and race. Despite its wide use, the instrument's latent factor structure and measurement invariance properties have not been reported in the published literature to date. Consequently, researchers regularly use subsets of the SSF's items without psychometric justification. Here, we explore and validate the SSF's factor structure and other psychometric properties, and we provide recommendations about how to score the measure. A one-factor model in Study 1 showed poor fit, and exploratory factor analyses extracted a four-factor solution. Study 2's confirmatory factor analyses demonstrated superior fit of a bifactor model with four specific factors (from Study 1) and one general factor. Ancillary analyses supported a total scale scoring method for the SSF and did not support computing raw subscale scores. We also tested the bifactor model's measurement invariance across gender and race, compared latent mean scores between groups, and established the model's criterion and concurrent validity. We discuss implications and suggestions for future research. (PsycInfo Database Record (c) 2023 APA, all rights reserved).