Para-infectious brain injury in COVID-19 persists at follow-up despite attenuated cytokine and autoantibody responses

To understand neurological complications of COVID-19 better both acutely and for recovery, we measured markers of brain injury, inflammatory mediators, and autoantibodies in 203 hospitalised participants; 111 with acute sera (1–11 days post-admission) and 92 convalescent sera (56 with COVID-19-associated neurological diagnoses). Here we show that compared to 60 uninfected controls, tTau, GFAP, NfL, and UCH-L1 are increased with COVID-19 infection at acute timepoints and NfL and GFAP are significantly higher in participants with neurological complications. Inflammatory mediators (IL-6, IL-12p40, HGF, M-CSF, CCL2, and IL-1RA) are associated with both altered consciousness and markers of brain injury. Autoantibodies are more common in COVID-19 than controls and some (including against MYL7, UCH-L1, and GRIN3B) are more frequent with altered consciousness. Additionally, convalescent participants with neurological complications show elevated GFAP and NfL, unrelated to attenuated systemic inflammatory mediators and to autoantibody responses. Overall, neurological complications of COVID-19 are associated with evidence of neuroglial injury in both acute and late disease and these correlate with dysregulated innate and adaptive immune responses acutely

Modelling nutrient-periphyton dynamics in streams: the importance of transient storage zones

The dynamics of a nutrient-limited periphyton community in a segment of stream was modeled. The stream segment was assumed to consist of two zones, free-flowing water and a boundary zone of zero water flow, which acted as a transient storage zone for nutrients. Studies with a biologically unreactive tracer solute (sodium chloride) were used to obtain parameters for diffusion of solute into the transient storage zone. Two simple alternative functional responses representing nutrient-limited periphyton growth were formulated, one with only nutrient limitation on periphyton growth and one that additionally included density-dependent limitation of periphyton growth. Attempts to fit the two alternative functional responses for periphyton growth and to predict nutrient levels in the transient storage zone showed that the two alternatives had very different implications for the steady state and dynamics of the storage zone. Empirical studies of periphyton biomass and nutrient turnover give support for the second alternative function. The model results suggests some additional experiments that can be performed to test the two alternatives. © 1995.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Heart valve function: a biomechanical perspective

Heart valves (HVs) are cardiac structures whose physiological function is to ensure directed blood flow through the heart over the cardiac cycle. While primarily passive structures that are driven by forces exerted by the surrounding blood and heart, this description does not adequately describe their elegant and complex biomechanical function. Moreover, they must replicate their cyclic function over an entire lifetime, with an estimated total functional demand of least 3×109 cycles. As in many physiological systems, one can approach HV biomechanics from a multi-length-scale approach, since mechanical stimuli occur and have biological impact at the organ, tissue and cellular scales. The present review focuses on the functional biomechanics of HVs. Specifically, we refer to the unique aspects of valvular function, and how the mechanical and mechanobiological behaviours of the constituent biological materials (e.g. extracellular matrix proteins and cells) achieve this remarkable feat. While we focus on the work from the authors' respective laboratories, the works of most investigators known to the authors have been included whenever appropriate. We conclude with a summary and underscore important future trends