Facilitated Assessment of Tissue Loss Following Traumatic Brain Injury

All experimental models of traumatic brain injury (TBI) result in a progressive loss of brain tissue. The extent of tissue loss reflects the injury severity and can be measured to evaluate the potential neuroprotective effect of experimental treatments. Quantitation of tissue volumes is commonly performed using evenly spaced brain sections stained using routine histochemical methods and digitally captured. The brain tissue areas are then measured and the corresponding volumes are calculated using the distance between the sections. Measurements of areas are usually performed using a general purpose image analysis software and the results are then transferred to another program for volume calculations. To facilitate the measurement of brain tissue loss we developed novel algorithms which automatically separate the areas of brain tissue from the surrounding image background and identify the ventricles. We implemented these new algorithms by creating a new computer program (SectionToVolume) which also has functions for image organization, image adjustments and volume calculations. We analyzed brain sections from mice subjected to severe focal TBI using both SectionToVolume and ImageJ, a commonly used image analysis program. The volume measurements made by the two programs were highly correlated and analysis using SectionToVolume required considerably less time. The inter-rater reliability was high. Given the extensive use of brain tissue loss measurements in TBI research, SectionToVolume will likely be a useful tool for TBI research. We therefore provide both the source code and the program as attachments to this article

Selective Inhibition of the Mitochondrial Permeability Transition Pore Protects against Neurodegeneration in Experimental Multiple Sclerosis

The mitochondrial permeability transition pore is a recognized drug target for neurodegenerative conditions such as multiple sclerosis and for ischemia-reperfusion injury in the brain and heart. The peptidylprolyl isomerase, cyclophilin D (CypD, PPIF), is a positive regulator of the pore, and genetic downregulation or knock-out improves outcomes in disease models. Current inhibitors of peptidylprolyl isomerases show no selectivity between the tightly conserved cyclophilin paralogs and exhibit significant off-target effects, immunosuppression, and toxicity. We therefore designed and synthesized a new mitochondrially targeted CypD inhibitor, JW47, using a quinolinium cation tethered to cyclosporine. X-ray analysis was used to validate the design concept, and biological evaluation revealed selective cellular inhibition of CypD and the permeability transition pore with reduced cellular toxicity compared with cyclosporine. In an experimental autoimmune encephalomyelitis disease model of neurodegeneration in multiple sclerosis, JW47 demonstrated significant protection of axons and improved motor assessments with minimal immunosuppression. These findings suggest that selective CypD inhibition may represent a viable therapeutic strategy for MS and identify quinolinium as a mitochondrial targeting group for <i>in vivo</i> use

Emotional behavior in aquatic organisms? Lessons from crayfish and zebrafish

Experimental animal models are a valuable tool to study the neurobiology of emotional behavior and mechanisms underlying human affective disorders. Mounting evidence suggests that various aquatic organisms, including both vertebrate (e.g., zebrafish) and invertebrate (e.g., crayfish) species, may be relevant to study animal emotional response and its deficits. Ideally, model organisms of disease should possess considerable genetic and physiological homology to mammals, display robust behavioral and physiological responses to stress, and should be sensitive to a wide range of drugs known to modulate stress and affective behaviors. Here, we summarize recent findings in the field of zebrafish- and crayfish-based tests of stress, anxiety, aggressiveness and social preference, and discuss further perspectives of using these novel model organisms in translational biological psychiatry. Outlining the remaining questions in this field, we also emphasize the need in further development and a wider use of crayfish and zebrafish models to study the pathogenesis of affective disorders. © 2019 Wiley Periodicals, Inc.MCS is currently supported by National Funds through FCT ‐ Foundation for Science and Technology. AVK is supported by the Russian Science Foundation grant 19‐15‐00053. KAD is supported by the Fellowship of the President of Russia and SPSU Rector Productivity Fellowship for PhD Students. CM is supported by CNPq/Brazil under Edital Universal 2016 (400726/2016‐5). PMA and FB are supported by the strategic plan of MARE ‐ Marine and Environmental Sciences Centre (UID/MAR/04292/2019)

Tamm Review: On the nature of the nitrogen limitation to plant growth in Fennoscandian boreal forests

The supply of nitrogen commonly limits plant production in boreal forests and also affects species composition and ecosystem functions other than plant growth. These interrelations vary across the landscapes, with the highest N availability, plant growth and plant species richness in ground-water discharge areas (GDAs), typically in toe-slope positions, which receive solutes leaching from the much larger groundwater recharge areas (GRAs) uphill. Plant N sources include not only inorganic N, but, as heightened more recently, also organic N species. In general, also the ratio inorganic N over organic N sources increase down hillslopes. Here, we review recent evidence about the nature of the N limitation and its variations in Fennoscandian boreal forests and discuss its implications for forest ecology and management. The rate of litter decomposition has traditionally been seen as the determinant of the rate of N supply. However, while N-rich litter decomposes faster than N-poor litter initially, N-rich litter then decomposes more slowly, which means that the relation between N % of litter and its decomposability is complex. Moreover, in the lower part of the mor-layer, where the most superficial mycorrhizal roots first appear, and N availability matters for plants, the ratio of microbial N over total soil N is remarkably constant over the wide range in litter and soil C/N ratios of between 15 and 40 for N-rich and N-poor sites, respectively. Nitrogen-rich and -poor sites thus differ in the sizes of the total N pool and the microbial N pool, but not in the ratio between them. A more important difference is that the soil microbial N pool turns over faster in N-rich systems because the microbes are more limited by C, while microbes in N-poor systems are a stronger sink for available N. Furthermore, litter decomposition in the most superficial soil horizon (as studied by the so-called litter-bag method) is associated with a dominance of saprotrophic fungi, and absence of mycorrhizal fungi. The focal zone in the context of plant N supply in N-limited forests is further down the soil profile, where ectomycorrhizal (ECM) roots become abundant. Molecular evidence and stable isotope data indicate that in the typical N-poor boreal forests, nitrogen is retained in saprotrophic fungi, likely until they run out of energy (available C-compounds). Then, as heightened by recent research, ECM fungi, which are supplied by photosynthate from the trees, become the superior competitors for N. In N-poor boreal soils strong N retention by microorganisms keeps levels of available N very low. This is exacerbated by an increase in tree C allocation to mycorrhizal fungi (TCAM) relative to net primary production (NPP) with decreasing soil N supply, which causes ECM fungi to retain much of the available soil N for their own growth and transfer little to their tree hosts. The transfer of N through the ECM fungi, and not the rate of litter decomposition, is likely limiting the rate of tree N supply under such conditions. All but a few stress-tolerant less N-demanding plant species, like the ECM trees themselves and ericaceous dwarf shrubs, are excluded. With increasing N supply, a weakening of ECM symbiosis caused by the relative decline in TCAM contributes to shifts in soil microbial community composition from fungal dominance to bacterial dominance. Thus, bacteria, which are less C-demanding, but more likely to release N than fungi, take over. This, and the relatively high pH in GDA, allow autotrophic nitrifying bacteria to compete successfully for the NH4+ released by C-limited organisms and causes the N cycle to open up with leaching of nitrate (NO3−) and gaseous N losses through denitrification. These N-rich conditions allow species-rich communities of N-demanding plant species. Meanwhile, ECM fungi have a smaller biomass, are supplied with N in excess of their demand and will export more N to their host trees. Hence, the gradient from low to high N supply is characterized by profound variations in plant and soil microbial physiologies, especially their relations to the C-to-N supply ratio. We propose how interactions among functional groups can be understood and modelled (the plant-microbe carbon-nitrogen model). With regard to forest management these perspectives explain why the creation of larger tree-free gaps favors the regeneration of tree seedlings under N-limited conditions through reduced belowground competition for N, and why such gaps are less important under high N supply (but when light might be limiting). We also discuss perspectives on the relations between N supply, biodiversity, and eutrophication of boreal forests from N deposition or forest fertilization

Plasticity and Inflammation following Traumatic Brain Injury

Traumatic Brain Injury (TBI) mainly affects young persons in traffic accidents and the elderly in fall accidents. Improvements in the clinical management have significantly improved the outcome following TBI but survivors still suffer from depression, memory problems, personality changes, epilepsy and fatigue. The initial injury starts a series of events that give rise to a secondary injury process and despite several clinical trials there is no drug available for clinical use that targets secondary brain injury mechanisms. Some recovery of function is seen during the first months following injury but is usually limited and there are no drugs that stimulate the recovery of lost function. Some of the recovery is attributed to plasticity, the brains ability to adapt to new circumstances, and enhancing plasticity via increased axonal growth has the potential to partly restore lost function. In this thesis mice were subjected to the controlled cortical impact model of TBI and functional outcome was evaluated using Morris water maze, the cylinder test and the rotarod. Brain tissue loss was measured in all Papers but the additional histological analyses differ among the Papers. Attempts to increase axonal growth were made by interfering with Nogo receptor function in Paper I and by conditional knockout of ephA4 in Paper II. Contrary to the hypothesis cognition was impaired in Paper I but otherwise no effects of treatment were detected in Paper I and II. Much is still unknown about plasticity and despite the discouraging results of Papers I and II this treatment approach is still worth further exploration. It is firmly established that TBI results in an inflammatory response and some aspects of it may damage brain tissue. In Papers III and IV the inflammatory response was attenuated using an IL-1β directed antibody which resulted in reduced tissue loss and edema while improving cognitive function. The results from Papers III and IV are encouraging and the possibility to find a treatment based on IL-1β inhibition appears promising