Sadri, A. | Search bioRxiv

bioRxiv2023

White Matter Correlates of Impulsive Behavior in Healthy Individuals: A Diffusion MRI Study

BackgroundImpulsivity is closely related to the tendency to engage in risky behaviors. Previous research identified macrostructural brain alterations in individuals exhibiting impulsive behaviors. Understanding the microstructural brain changes linked to impulsivity can elucidate its underlying mechanisms and guide effective treatment strategies. In this study, we employed diffusion magnetic resonance imaging (DMRI) connectometry to investigate white matter tracts associated with impulsivity while considering potential sex differences. MethodsWe enrolled 218 healthy participants from the Leipzig Study for Mind-Body-Emotion Interactions (LEMON) database. Correlations between DMRI-derived white matter changes and impulsivity were assessed using scores from the UPPS Impulsive Behavior Scales four subscales (lack of perseverance (PE), lack of premeditation (PM), sensation seeking (SS), and negative urgency (NU)). ResultsOur findings revealed negative correlations between quantitative anisotropy (QA) values in bilateral cerebellum, middle cerebellar peduncle (MCP), and the severity of PE and PM across the cohort. Additionally, QA values within MCP, corpus callosum (CC) body, and forceps major exhibited negative correlations with SS. Conversely, QA values in forceps minor were positively correlated with PM, and QA values in both the forceps minor and bilateral cingulum showed positive correlations with SS. Remarkably, the observed correlations between UPPS subscale scores and QA value alterations within white matter tracts varied between males and females. ConclusionsImpulsivity is correlated with discernible alterations in white matter integrity across diverse tracts, including CC, cerebellum, and cingulum. Moreover, males and females show distinct patterns of correlations between white matter integrity and impulsivity. HighlightsO_LIImpulsivity is associated with QA changes and white matter alterations in various brain tracts. C_LIO_LILower white matter integrity in the cerebellum is negatively correlated with impulsivity. C_LIO_LIQA values in the CC parts showed divergent correlations with impulsive behavior. C_LIO_LIThe patterns of correlations across various tracts varied between males and females. C_LI

neuroscience↗

bioRxiv2020

Direct Observation of the Mechanism of Antibiotic Resistance by Mix-and-Inject at the European XFEL

In this study, we follow the diffusion and buildup of occupancy of the substrate ceftriaxone in M. tuberculosis {beta}-lactamase BlaC microcrystals by structural analysis of the enzyme substrate complex at single millisecond time resolution. We also show the binding and the reaction of an inhibitor, sulbactam, on a slower millisecond time scale. We use the mix-and-inject technique to initiate these reactions by diffusion, and determine the resulting structures by serial crystallography using ultrafast, intense X-ray pulses from the European XFEL (EuXFEL) arriving at MHz repetition rates. Here, we show how to use the EuXFEL pulse structure to dramatically increase the size of the data set and thereby the quality and time resolution of "molecular movies" which unravel ligand binding and enzymatically catalyzed reactions. This shows the great potential for the EuXFEL as a tool for biomedically relevant research, particularly, as shown here, for investigating bacterial antibiotic resistance. One Sentence SummaryDirect observation of fast ligand binding in a biomedically relevant enzyme at near atomic resolution with MHz X-ray pulses at the European XFEL.

biophysics↗