High Force Unimanual Handgrip Contractions Increase Ipsilateral Sensorimotor Activation and Functional Connectivity

Imaging and brain stimulation studies seem to correct the classical understanding of how brain networks, rather than contralateral focal areas, control the generation of unimanual voluntary force. However, the scaling and hemispheric-specificity of network activation remain less understood. Using fMRI, we examined the effects of parametrically increasing right-handgrip force on activation and functional connectivity among the sensorimotor network bilaterally with 25%, 50%, and 75% maximal voluntary contractions (MVC). High force (75% MVC) unimanual handgrip contractions resulted in greater ipsilateral motor activation and functional connectivity with the contralateral hemisphere compared to a low force 25% MVC condition. The ipsilateral motor cortex activation and network strength correlated with relative handgrip force (% MVC). Increases in unimanual handgrip force resulted in greater ipsilateral sensorimotor activation and greater functional connectivity between hemispheres within the sensorimotor network. (C) 2020 IBRO. Published by Elsevier Ltd. All rights reserved

Central Role of Manganese in Regulation of Stress Responses, Physiology, and Metabolism in Streptococcus pneumoniae ▿ †

The importance of Mn2+ for pneumococcal physiology and virulence has been studied extensively. However, the specific cellular role(s) for which Mn2+ is required are yet to be fully elucidated. Here, we analyzed the effect of Mn2+ limitation on the transcriptome and proteome of Streptococcus pneumoniae D39. This was carried out by comparing a deletion mutant lacking the solute binding protein of the high-affinity Mn2+ transporter, pneumococcal surface antigen A (PsaA), with its isogenic wild-type counterpart. We provide clear evidence for the Mn2+-dependent regulation of the expression of oxidative-stress-response enzymes SpxB and Mn2+-SodA and virulence-associated genes pcpA and prtA. We also demonstrate the upregulation of at least one oxidative- and nitrosative-stress-response gene cluster, comprising adhC, nmlR, and czcD, in response to Mn2+ stress. A significant increase in 6-phosphogluconate dehydrogenase activity in the psaA mutant grown under Mn2+-replete conditions and upregulation of an oligopeptide ABC permease (AppDCBA) were also observed. Together, the results of transcriptomic and proteomic analyses provided evidence for Mn2+ having a central role in activating or stimulating enzymes involved in central carbon and general metabolism. Our results also highlight the importance of high-affinity Mn2+ transport by PsaA in pneumococcal competence, physiology, and metabolism and elucidate mechanisms underlying the response to Mn2+ stress