Endurance performance involves the prolonged maintenance of constant or self-regulated power/velocity or torque/force. While the impact of numerous determinants of endurance performance has been previously reviewed, the impact of fatigue on subsequent endurance performance still needs to be documented. This review aims to present the impact of fatigue induced by physical or mental exertion on subsequent endurance performance. For the purpose of this review, endurance performance refers to performance during whole-body or single-joint endurance exercise soliciting mainly the aerobic energy system. First, the impact of physical and mental exertion on force production capacity is presented, with specific emphasize on the fact that solely physical exertion and not mental exertion induces a decrease in force production capacity of the working muscles. Then, the negative impact of fatigue induced by physical exertion and mental exertion on subsequent endurance performance is highlighted based on experimental data. Perception of effort being identified as the variable altered by both prior physical exertion and mental exertion, future studies should investigate the underlying mechanisms increasing perception of effort overtime and in presence of fatigue during endurance exercise. Perception of effort should be considered not only as marker of exercise intensity, but also as a factor limiting endurance performance. Therefore, using a psychophysiological approach to explain the regulation of endurance performance would allow a better understanding of the interaction between physiological and psychological phenomena known to impact endurance performance. Endurance performance involves the prolonged maintenance of constant or self-regulated power/velocity ; or single-joint exercises . While whole-body exercises present the advantage of replicating real sport events in laboratory conditions, single-joint exercises provide a unique exercise model to investigate underlying mechanisms thought to impact endurance performance. As an example, single-joint exercises present the advantage of reducing the time delay between the end of the endurance exercise and the start of neuromuscular testing  of endurance performance has been previously reviewed  compared to voluntary contractions (−6.4%), thus in relation to the extent of KE MVC reduction . To the best of our knowledge, this study is the first to report a decrease in endurance performance induced by fatigue of a muscle group involved in subsequent endurance exercise. Similar results were observed by Amann and Dempsey  force production capacity, using either electromyostimulation or voluntary contractions, on the VO Dempsey  with a d Dempsey . For thi Dempsey  performe Dempsey , 2002. MIn 1984, Sherman and colleagues demonstrated that completion of a marathon decreases the amount of work performed during a work capacity test consisting in the repetition of 50 maximal leg extensions (duration of the endurance exercise ~2 min). This impairment in endurance performance was confirmed by Neyroud et al. . In this2max (−14%) achieved during a graded exercise  and testing a lower body (or upper body) muscle group endurance performance. With regard to endurance performance of the controlateral limb, Amann et al.  demonstrSince the first study of Marcora et al.  demonstrTo the best of our knowledge, only one study investigated the impact of prior mental exertion on endurance performance. In this study, Pageaux et al.  demonstrAs demonstrated by the studies included in this review , defined as “the feeling of how hard, heavy and strenuous a physical task is” Marcora, , is a coBy integrating experimental results from different exercise modes and published by different research groups, this review provides evidence that fatigue induced by prior physical or mental exertion impairs subsequent endurance performance. While impairments in endurance performance are not associated with a common physiological alteration, perceived exertion seems to be the common variable altered by fatigue. Consequently, future studies should investigate the cause of the progressive increase in perceived exertion overtime during endurance exercise and consider perceived exertion not only as marker of exercise intensity, but also as a factor limiting endurance performance. Furthermore, as psychological interventions such as self-talk  and the Fonds Européen de Développement Régional (FEDER). The funders of the postdoctoral position had no role in decision to publish, or preparation of the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Interventions using the “Four Immeasurables Meditations” (FIM) are effective for various outcomes; however, whether increased meditation practice in these interventions leads to better results has not been well investigated. This systematic review included 22 FIM interventions that reported associations between the amount of meditation practice and its outcomes. Despite the heterogeneity in intervention components and outcome variables, there were generally few significant associations between amount of meditation practice and its outcomes. Specifically, only five studies reported that more than half of the calculated results were significant. In comparison with correlations between total amount of practice and overall outcomes, the short-term influence of meditation practice was evaluated in fewer studies; however, it had a better association with outcomes. More studies are required that address the underlying mechanisms that elucidate how meditation practice leads to outcome changes in daily life. In this study, two promising mechanisms with initial evidence were discussed. This review also summarized common methodological issues including a lack of experimental manipulation and inaccurate measuring of meditation practice. Buddhism emphasizes the cultivation of four “sublime” or “noble” attitudes toward all beings: loving-kindness (friendliness), compassion (willing to cease suffering), appreciative joy (feeling happy for others), and equanimity . These are known as the “four immeasurables” Sujiva, . These aEmpirical studies on the effects of FIM have increased sharply in recent years, and a series of studies evaluated the effects of interventions based on FIM on various outcomes  AND Joy] OR equanimity OR metta OR mudita OR karuna OR upekkha” combined with “MeditatThe inclusion criteria were (a) articles published in a peer-reviewed journal in English, (b) empirical studies addressing interventions wherein at least 50% of major practices were FIM, and (c) studies that reported a relationship between the amount of meditation practice and other variables.The first two authors reviewed the titles and abstracts of unduplicated records to identify potential relevant articles for full text review; then, they extracted information about the amount of meditation practice from empirical studies on FIM. The reference lists of identified empirical studies were checked for missing articles. We attempted to contact the authors for unexplained selective reports; however, some researchers had not provided contact information or did not reply.N = 1509) were collected and 135 articles were obtained for full text review. Among them, 77 articles were identified as empirical studies on FIM, and one more article  articles on FIM interventions evaluated the relationship between amount of meditation practice and dependent (and/or independent) variables, which reflects the fact that current studies on amount of meditation practice or more generally, on active components, are still limited. Among them, four studies , five studies used biological or physiological indicators , and five studies measured brain activation in different tasks , but effect of amount of meditation practice existed. Pace et al.  noted thAnother issue, pointed out by reviewers of current article, is that the length of reviewed interventions was no longer than 8 weekly sessions, which was far shorter than years of meditation practice in traditional Buddhist training. Therefore, researchers should be cautious when generalizing the conclusion. Furthermore, the limited duration of interventions also limit the variance in amount of meditation practice; therefore, it is possible that larger differences in meditation experience , to predict the outcomes. Only four studies measured daily outcomes and explored their relationship with daily meditation practice  assumption that meditation practice has its effects in a cumulative way through long-term practice, while few researchers explored a pattern of short-term change. In addition, although most Buddhist traditions encourage long-term meditation practice, Zen Buddhism claims a potential “sudden change,” which asserts that the enlightenment can occur with an instant revelation Suzuki, . AlthougHow meditation practice leads to changes in daily life was not well explained. For example, Fredrickson et al.  identifiFrom meditation practice to daily outcomes, one of the potential mechanisms is that repeated meditation practice makes practitioners more effective in an active application of FIM. Therefore, this enhances the effectiveness of emotional regulation when this is needed by practitioners. For example, previous studies showed that active application of CM when seeing the suffering of others generated positive feelings, which could regulate practitioners' emotions and let them approach and help suffering people (Klimecki et al., Another mechanism for further investigation is that daily FIM practice affects short-term mental status, such as by inducing positive moods, and this leads to further change in daily life. This mechanism is more consistent with those studies that explored the short-term associations between amount of practice and outcomes as discussed above. Current studies indicated that FIM practice on a given day can influence one's life the same morning (Fredrickson et al., The importance of meditation practice was supported by the correlations between the amount of meditation practice and outcomes; however, it is worth noting that this result may be confounded by other factors. The fundamental issue here is that the relationship between amount of meditation and effects in the reviewed studies is essentially correlational. That is, the researchers did not manipulate the amount of meditation practice into high vs. low levels, thus the causal relationships between meditation practice and outcomes cannot be confirmed. Fredrickson et al.  and MascAt the same time, methodological issues can obscure the relationship between meditation practice and effects, even when this relationship exists. The low reliability of meditation practice records has been noted above. Researchers also noted the possibility that the quality of practice is more important than the amount of practice (Shapiro et al., Two major limitations of the current review should be noted. First, this review was limited to articles published in journals; other resources, such as dissertations, might add more information. However, we believe the published articles represent the current paradigm in investigating the effects of meditation practice, and our summary of different perspectives and methodological issues should not have been heavily impacted by missing unpublished studies. Second, we discussed the issue of selective reporting, but did not provide a comprehensive risk of bias assessment. This is because the current review focused on associations between amount of meditation practice and outcome variables, which is largely limited to FIM intervention groups and was less concerned with typical risks of bias such as randomization between groups or allocation concealment.Whether more meditation practice leads to better outcomes in FIM interventions has received insufficient research attention. Current evidence shows that the amount of meditation practice has limited associations with outcomes. In addition to correlations between total amount of practice and daily outcomes, the short-term influence of FIM and the ability of actively applying FIM skills present promising perspectives to understand the contribution of meditation practice. Experimental manipulation and better measurement of meditation practice are needed in future studies.XZ, FL, and XL designed the study. XZ and FC reviewed articles and analyzed the data. XZ and TO wrote the paper. All authors discussed the results and commented on the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Invaginating structures at chemical synapses in the mammalian nervous system exist in presynaptic axon terminals, postsynaptic spines or dendrites, and glial processes. These invaginating structures can be divided into three categories. The first category includes slender protrusions invaginating into axonal terminals, postsynaptic spines, or glial processes. Best known examples of this category are spinules extending from postsynaptic spines into presynaptic terminals in forebrain synapses. Another example of this category are protrusions from inhibitory presynaptic terminals invaginating into postsynaptic neuronal somas. Regardless of the direction and location, the invaginating structures of the first category do not have synaptic active zones within the invagination. The second category includes postsynaptic spines invaginating into presynaptic terminals, whereas the third category includes presynaptic terminals invaginating into postsynaptic spines or dendrites. Unlike the first category, the second and third categories have active zones within the invagination. An example of the second category are mossy terminal synapses of the hippocampal CA3 region, in which enlarged spine-like structures invaginate partly or entirely into mossy terminals. An example of the third category is the neuromuscular junction (NMJ) where substantial invaginations of the presynaptic terminals invaginate into the muscle fibers. In the retina, rod and cone synapses have invaginating processes from horizontal and bipolar cells. Because horizontal cells act both as post and presynaptic structures, their invaginating processes represent both the second and third category. These invaginating structures likely play broad yet specialized roles in modulating neuronal cell signaling. The classic image of a neuronal synapse with a bulbous presynaptic terminal separated from a postsynaptic dendrite shaft or spine Figure  is oftenThese invaginating protrusions can be derived from the postsynaptic, presynaptic or glial components of synapses. Although active zones often lie adjacent to the invaginating structures, they do not have any active zone within the invagination  and contain active zones within the invagination Figure .A modest variety of invaginating presynaptic terminal structures occur, including in developing auditory nerve endbulbs on neuron somas in the cat, vestibular nerve terminals on neuron somas of the rat lateral vestibular nucleus, crested dendrites in the rat interpeduncular nucleus, and cup-shaped spines  of most animals, invertebrate and vertebrate, presynaptic terminals are indenting or invaginating into muscle fibers; thus, some kinds of terminals are found in a shallow, elongate indention (“gutter”) on the surface of the fiber, while others are invaginating completely into the fiber Figure . Most skcategory 2; Petralia et al., Mossy fiber terminal (MFT) synapses in the CA3 area  of the hippocampus form unusual synapses with invaginating postsynaptic, spine-like processes called thorny excrescences (category 1) are common on excrescences  including two from horizontal cell neurons and one or two from bipolar cell neurons ; these can be presynaptic to both the photoreceptor terminal and the bipolar cell processes. It is common to find numerous vesicles in the invaginated horizontal cell processes; good examples are found in rats, monkeys and humans; in addition, there is good evidence that the latter processes can be GABAergic (Petralia et al., Interestingly, at least the horizontal cell processes also appear to act as invaginating presynaptic terminals (Invaginating structures are common at synapses and are associated either with developmental plasticity or are integral to the mature synapse structure. In some cases, like the hippocampal MFTs or NMJs, mammals may show particularly well-developed invaginating synaptic structures, reflecting perhaps evolutionary enhancements in the mammalian brain and in brain-muscle coordination. The three categories differ in structure, but in all cases, the invaginated synapse forms a special, enclosed environment that allows wide movement of neurotransmitters and/or other chemicals while excluding other substances, leading to modifications in neurotransmission or selective chemical signaling between the neurons. The invagination also may be specialized for signaling via ephaptic conduction. This has been studied so far in only a few areas such as the retina, but it is likely a widespread mechanism for synaptic modulation, as noted by Gardner et al. .RSP, MPM and PJY wrote the manuscript and RSP, Y-XW and PJY contributed to the figures.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Deeper exploration of the brain’s vast synaptic networks will require new tools for high-throughput structural and molecular profiling of the diverse populations of synapses that compose those networks. Fluorescence microscopy (FM) and electron microscopy (EM) offer complementary advantages and disadvantages for single-synapse analysis. FM combines exquisite molecular discrimination capacities with high speed and low cost, but rigorous discrimination between synaptic and non-synaptic fluorescence signals is challenging. In contrast, EM remains the gold standard for reliable identification of a synapse, but offers only limited molecular discrimination and is slow and costly. To develop and test single-synapse image analysis methods, we have used datasets from conjugate array tomography (cAT), which provides voxel-conjugate FM and EM (annotated) images of the same individual synapses. We report a novel unsupervised probabilistic method for detection of synapses from multiplex FM (muxFM) image data, and evaluate this method both by comparison to EM gold standard annotated data and by examining its capacity to reproduce known important features of cortical synapse distributions. The proposed probabilistic model-based synapse detector accepts molecular-morphological synapse models as user queries, and delivers a volumetric map of the probability that each voxel represents part of a synapse. Taking human annotation of cAT EM data as ground truth, we show that our algorithm detects synapses from muxFM data alone as successfully as human annotators seeing only the muxFM data, and accurately reproduces known architectural features of cortical synapse distributions. This approach opens the door to data-driven discovery of new synapse types and their density. We suggest that our probabilistic synapse detector will also be useful for analysis of standard confocal and super-resolution FM images, where EM cross-validation is not practical. Brain function results from communication between neurons connected by complex synaptic networks. Synapses are themselves highly complex and diverse signaling machines, containing protein products of hundreds of different genes, some in hundreds of copies, precisely arranged at each individual synapse. Synapses are fundamental not only to synaptic network function but also to network development, adaptation, and memory. In addition, abnormalities of synapse numbers or their molecular components have been implicated in a variety of mental and neurological disorders. Despite their obvious importance, mammalian synapse populations have so far resisted detailed quantitative study. In human brains and most animal nervous systems, synapses are very small and very densely packed: there are approximately 1 billion synapses per cubic millimeter of human cortex. This volumetric density poses very substantial challenges to proteometric analysis at the critical level of the individual synapse. The present work describes new probabilistic image analysis methods suitable for single-synapse analysis of synapse populations in both animal and human brains, in health and disorder. Deeper understanding of the basic mechanisms and pathologies of the brain’s synaptic networks will require advances in our quantitative understanding of structural, molecular, and functional diversity within the vast populations of individual synapses that define those networks  2] 3]  [3] 2] [  [3] 2] unsupervised framework. The probabilistic detection algorithm we introduce has perhaps its closest precedent in probabilistic synapse detectors that were introduced recently for the analysis of Focussed Ion Beam Scanning Electron Microscope (FIBSEM) images [The synapse detection methodology described here is not the first to grapple with the challenges of detecting synapses in immunofluorescence images  7] 8]  [8] 7] [  [8] 7] ) images  13]. Th. ThunsupSingle-synapse profiling of large and diverse synapse populations poses formidable challenges  15] [16 [1615]  18]. Un. Un18]. In designing the algorithm and software reported here, we first relied on images acquired with conjugate array tomography (cAT), which combines the strengths of FM-AT with those of electron microscopic array tomography (EM-AT), allowing both EM and muxFM imaging of individual cortical specimens. Array tomography’s ultrathin physical sectioning provides z-axis resolution far beyond the light microscopic diffraction limit, as well as high sensitivity and high lateral resolution, while greatly simplifying voxel-conjugate registration of FM-AT and EM-AT images. FM-AT can moreover multiplex large numbers of synaptic markers by its combination of sequential and spectral label multiplexing. Thus, cAT provides an ideal platform for the development and rigorous design and testing of algorithms aimed at single-synapse molecular analysis and population molecular profiling.The remarkable structural and molecular diversity within mammalian synapse populations challenges our present biological understanding of how to define a synapse . DifficuThe unsupervised probabilistic synapse detector reported here accepts molecular-morphological synapse models in the form of user queries, and delivers a volumetric map of the probability that each voxel represents part of a synapse. These maps can then be used directly to detect, classify, and map putative synapses, with confidence statistics for each. Taking human annotation of cAT EM data as ground truth, we show that our algorithm detects synapses from muxFM data alone as effectively as human annotators (while seeing only the muxFM data), and can reproduce known architectural features of cortical synapse distributions. The algorithm is actually validated with the most comprehensive AT datasets currently available. Though we here address only array tomography image data, our probabilistic synapse detector may also be useful for analysis of widely available confocal and super-resolution FM images.The proposed algorithm is inspired from biological knowledge of synapse characteristics. Synapses include two major structural components: a presynaptic terminal and a postsynaptic terminal. Detecting synapses using data from immunofluorescence imaging involves identifying such adjacent presynaptic and postsynaptic antibody markers, as shown in Manual synapse identification involves determining the punctum size and brightness in one channel, and then considering adjacency to similarly-defined puncta in other channels. However, without corresponding EM data, detections using only IF data have an associated degree of uncertainty. Thus, we propose a query-based probabilistic synapse detection method that reflects the thought process underlying expert manual synapse detection.The first step is to distinguish signal from background noise. This calculation encodes the probability that the pixel value represents authentic antigen detection. The second step is to determine whether the foreground pixels correspond to a 2D punctum, since photons emanating from only a single pixel usually reflect noise. Therefore, adjacent ‘positive’ pixels, more likely to reflect a synaptic punctum, are augmented. Third, puncta that span multiple slices have a higher probability of belonging to a synapse than those that do not. To visualize this effect, the probability of a punctum belonging to a synapse is attenuated based on whether the prospective punctum spans multiple slices. The last step in computing the synapse probability map is to evaluate the presence of adjacent presynaptic and postsynaptic puncta by correlating the corresponding IF volumes. This produces a probability map, where the value at each voxel is the probability it belongs to a synapse. This algorithm provides a general framework for the evaluation of a wide variety of synapse subtypes, user-defined by setting the presynaptic and postsynaptic antibodies and puncta size.supervised training). EM data allows the user to differentiate between symmetric and asymmetric synapses, but does not allow for subtype identification (limited labels/supervision). Thus, the support vector machine (SVM) classifier used in 19]. ThesAll the primary antibodies used are from commercial sources see  and havepsynap, from each query was thresholded, and adjacent voxels that lie over the threshold were grouped into detections.The proposed method was first evaluated on the cAT dataset published in  using thThe ground truth used in this work is obtained from the EM data since it represents the current ‘gold standard’ for manual synapse identification. Prior to imaging with scanning electron microscope (SEM), the tissue was embedded in Lowicryl, which preserves fine ultrastucture detail . Not eveWe report in IF only indicator, we observe that the algorithm performs at human level (approximately 90% accuracy), with false positives and false negatives limited to cases which human experts (including co-authors of this manuscript) are also not confident of their own result  [27 [27μm3 oFor this dataset, the query parameters were adjusted to reflect the different synaptic markers used. Tables Once the probability maps were computed , they wePrevious quantitative electron microscopy indicates that the synapse density should be higher in Layer IV than in Layer V , consistThe threshold of the estimated probability can be set to optimize a specific desired property (density in this case), thereby becoming an additional ‘query.’ The threshold can actually add flexibility, since different thresholds might lead to selective detection of different types of synapses. This possibility will be studied when new data becomes available, now that the unsupervised algorithm here introduced can be applied to such data . This means that the only non-straightforwardly physical parameter of the proposed algorithm  can add flexibility to the technique. Finally, the threshold can be ignored if we work directly with the probability map 2, a number found by [Thresholding in  was donefound by  to be thThe proposed synapse detection method serves the potential future needs of both basic and clinical neuroscience. Methods for large-scale synapse detection could analyze image volumes large enough to contain complete neural arbors, and thus allow the discernment of the relationships between detected synapses and their presynaptic and postsynaptic parent neurons. An understanding of the statistics of synapse variation in any given synaptic network is certain to be critical to interpreting and modeling results of mechanistic physiological study. Moreover, advances in imaging methods for tracing complete axonal and dendritic arbors  are likeThis work introduces a model-based unsupervised synapse detection algorithm that incorporates fundamental biological knowledge of how synapses are identified in the immunofluorescence data. We created a series of probabilistic excitatory detectors for various subtypes of synapses, and included the 3D spatial relationships typical of synaptic structures. This novel approach provides a probabilistic-based detection algorithm yielding not only detection but detection with confidence values. The implementation of synapse detection as a probability map , as opposed to a binary detection / no-detection result may provide a powerful tool to assist experts throughout the exploratory process to gain new insights from the immunofluorescence data, including potentially discovering new subtypes of synapses. The influence of different biological and AT components on the actual probability values, from the noise of the system to the expression level of the proteins and the subclass of the synapses, an important new topic of investigation, will become possible when the proposed algorithm is applied to large new datasets, currently being generated. Creating conjugate Array Tomography datasets require specialized equipment, including the use of a Field Emission Scanning Electron Microscope (FESEM) to provide ground truth validation of synapse results. The computational work presented in this paper, together with the publicly available code and data, is a step in the direction of making this kind of analysis robust enough to no longer require expensive FESEM validation.The algorithm is computationally very simple and the only parameters are the user’s definition of a synapse subtype, rendering it ready for massive datasets. The results were validated with the best available cAT and AT data, producing state-of-the-art results without the need for supervised training. As demonstrated here, the proposed framework can be exploited for the explicit detection of synapses or their properties, the latter being critical for the discovery of new subtypes as well as the patterns of distributions of known subtypes. These, and the potential consequences of the approach here proposed to other modalities, are the subjects of our current efforts.


Hippocampal volume was reduced in the perinatal brain injury group relative to controls  and was positively correlated with striatal dopamine synthesis capacity . This is the first evidence in humans linking neonatal hippocampal injury to adult dopamine dysfunction, and provides a potential mechanism linking early life risk factors to adult mental illness.Perinatal brain injuries, including hippocampal lesions, cause lasting changes in dopamine function in rodents, but it is not known if this occurs in humans. We compared adults who were born very preterm with perinatal brain injury to those born very preterm without perinatal brain injury, and age-matched controls born at full term using [18F]-DOPA PET and structural MRI. Dopamine synthesis capacity was reduced in the perinatal brain injury group relative to those without brain injury  have abnormal levels of dopamine. Changes in brain dopamine levels may explain why early-life brain injury is linked to later mental illness. But first scientists must study whether similar changes occur in humans with an early-life brain injury.Now, Froudist-Walsh et al. use brain imaging to show that people born very early who suffered a brain injury have lower dopamine levels than other adults. Imaging techniques were used to scan the brains of 13 adults who were born before 32 weeks and who had a brain injury around birth, 13 adults born before 32 weeks without a brain injury, and 13 adults born at “full term” (around 39 to 40 weeks). Individuals with low dopamine levels reported difficulty concentrating and a lack of motivation and enjoyment in their lives. Both can be warning signs of mental health problems.People born prematurely without a brain injury had normal dopamine levels and did not report such symptoms. More studies may help scientists understand how early brain injuries may cause brain chemical differences later in life, and how these brain changes affect individual’s mental health. They may also help scientists develop treatments to prevent or treat mental illness in people who experienced a brain injury after a very early birth. More than 10% of babies born in the USA are born preterm (born before 37 weeks of gestation), and about 2% are born very preterm  . PrematuThe second and third trimesters of gestation are critical periods for neurodevelopment, particularly for axon and synapse formation, glial proliferation and the development of neurotransmitter systems including the dopaminergic system . Thus, VThe sequelae of VPT birth include long-lasting and widespread structural brain alterations, with hippocampal and prefrontal cortical development consistently affected . There iIn rodents, neonatal hippocampal lesions lead to disrupted development of the prefrontal cortex . We haveHowever, it is not known if perinatal brain injury is associated with dopaminergic alterations in adulthood in humans, or how this relates to hippocampal and prefrontal structural alterations. We aimed to disentangle the preclinical, post-mortem and indirect clinical evidence regarding the effects of early brain insults on later dopamine function by directly comparing two contrasting hypotheses, namely that early brain injury leads to hyper-, or alternatively hypo-dopaminergia in the striatum. Moreover, in view of the preclinical findings showing that perinatal hippocampal lesions can lead to lasting alterations to the dopamine system , and theWe set out to test these hypotheses by studying striatal dopamine synthesis capacity using [18F]-DOPA PET scans and hippocampal volume using structural MRI in adults who were born VPT with evidence of macroscopic perinatal brain injury who have been followed longitudinally for their entire lives, and compared them to two control groups, one group of individuals born VPT without evidence of macroscopic perinatal brain injury, and a group of controls without a history of VPT birth or perinatal brain injury.Seventeen individuals from the VPT-perinatal brain injury group, fourteen from the VPT-no diagnosed injury group and fourteen from the term-born control group were recruited. One VPT-perinatal brain injury participant was excluded from both PET and MRI analysis as a diagnosis of hypothyroidism was discovered at assessment. Incomplete PET data were acquired in one subject from the VPT-no diagnosed injury group because the participant felt unwell and finished the PET scan early. This participant was also excluded from further analysis. In addition to the two participants  excluded from the PET study, four further participants  were not included in the MRI study due to contraindications to scanning. Thus, thirteen individuals from the VPT-perinatal brain injury group, thirteen from the VPT-no diagnosed injury group and thirteen from the term-born control group had complete PET- and MRI-derived measures.VPT-perinatal brain injury participants had a lower gestational age and birth weight than VPT-no diagnosed injury participants . This waicer corresponding to a partial eta-squared of 0.233  and controls  in the whole striatum with large effect sizes  in the whole striatum  and the caudate nucleus  but not the nucleus accumbens . Furthermore, when just including the participants who also took part in the MRI study , reduced Kicer in the VPT-perinatal brain injury group remained significant in the whole striatum , the caudate nucleus  and in the nucleus accumbens .Additional sensitivity analyses showed that the reduction in Kicer in the VPT-perinatal brain injury group remained significant when co-varying for age, IQ, region-of-interest  volume and intracranial volume in the whole striatum , the caudate nucleus  and in the nucleus accumbens .The reduction in Kicer, perinatal brain injury remained a significant predictor of dopamine synthesis capacity , but neither gestational age at birth , nor birth weight  significantly predicted dopamine synthesis capacity.The two VPT groups differed not only on perinatal brain injury status, but also on gestational age at birth and birth weight . Furthericer varied across striatal subregions, we performed a repeated-measures ANOVA with striatal subregion as the within-subjects factor, group as the between subjects factor and Kicer as the dependent variable. There was no significant subregion-by-group interaction . As expected, there were significant effects of subregion (F = 81.26 p<0.001) and group .In order to further probe whether group differences in KThere was a significant difference in hippocampal volumes across the three groups . The VPTOn assessing striatal volume with repeated-measures ANOVA, with striatal sub-region volume as a within-subjects factor and group as a between-subjects factor, we found no significant main effect of group (p=0.081) and no significant group*subregion interaction (p=0.123).Analysing the whole striatum and each sub-region separately using one-way ANOVAs and post-hoc t-tests confirmed that there were no significant between-group volumetric differences in the striatum .We additionally analysed the estimated striatal volumes for all individuals with PET scans (i.e. including those without MRI), and again found that there were no significant between group differences in striatal volume as a whole  or in any striatal subregion after FDR correction for multiple comparisons , although there was a trend for differences between groups in the volume of the nucleus accumbens, which did not reach significance .There were no statistically significant differences between the control group and both VPT groups in dlPFC volume .icer in the caudate .A significant correlation was observed between hippocampal volume and Kicer as the dependent variable. We found a significant effect of hippocampal volume , but no hippocampal volume by striatal subregion interaction . Additionally, there was no significant effect of ICV on Kicer . We then examined whether the relationship between hippocampal volume and striatal Kicer varied significantly by group, again by using region as a within-subjects factor, and this time having group and the group-by-hippocampal-volume interaction term as between-subjects factors. Again we found a significant main effect of group , but no group by hippocampal volume interaction .In order to test the interaction between hippocampal volume and striatal subregion, we again performed a repeated-measures ANOVA, with subregion as the within-subject factor, hippocampal volume and intracranial volume as covariates and and KWe recently conducted a large-scale structural analysis in an overlapping sample . In thaticer in the two subregions of the striatum which previously showed significant associations with hippocampal volume, namely the caudate nucleus and the nucleus accumbens, and used hippocampal and dlPFC volumes as independent variables. In the caudate model, hippocampal volume was still a significant predictor of dopamine synthesis capacity , but dlPFC volume was not . This was also the case when using relative, instead of raw dlPFC volumes . In the nucleus accumbens model, neither the hippocampus  nor the dlPFC  significantly predicted dopamine synthesis. Again, using relative dlPFC volumes did not alter the result .Using a general linear model, we used as dependent variables KWe recently demonstrated that in adulthood individuals born very preterm continue to display impairments in executive function, which are associated with less real-life achievement . StriataWe performed an additional exploratory analysis to assess whether dopamine synthesis capacity was associated with performance on the Hayling Sentence Completion Test , ControlWe found no significant associations between striatal dopamine synthesis capacity and executive function in any group .We recently showed in an expanded sample, including the subjects from the present study, that adults born very preterm are more likely to exhibit subclinical symptoms across a range of symptom dimensions , as asseWe found that, across the entire study sample, there was a negative correlation between dopamine synthesis capacity in the nucleus accumbens, and cognitive symptoms identified by the CAARMS .At a group level, there was a significant negative correlation between nucleus accumbens dopamine synthesis capacity in the VPT-PBI group, and both cognitive  and negative symptoms . There were no significant correlations between dopamine synthesis capacity and subclinical symptoms in the other two groups, or in other striatal subregions .Adults with a history of macroscopic perinatal brain injury associated with VPT birth had reduced dopamine synthesis capacity in the striatum compared to controls born VPT and those born at term, and reduced hippocampal volume compared to individuals born at term. Individuals born similarly preterm but without evidence of macroscopic brain injury showed no significant differences in presynaptic dopamine synthesis capacity from controls, suggesting that preterm birth in the absence of macroscopic brain injury is not sufficient to disrupt striatal dopaminergic function in adult life.It is possible that perinatal brain insults resulted in a long-lasting reduction in the number of dopaminergic neurons  or causeWe also found that reduced striatal dopamine synthesis capacity was associated with reduced hippocampal volume. Several preclinical models, including the MAM model  and adul2 receptor antagonist  concentrations indicating reduced dopamine synthesis in response to stress and amphetamine in the lesioned group compared to controls . AnotherThis suggests that similar behavioural symptoms can be evoked by either increased presynaptic dopamine synthesis and release or other mechanisms, such as increased postsynaptic D2 receptor sensitivity. The present study suggests that the first mechanism is not present in humans who were born very preterm or suffered perinatal brain injury. It should also be recognized that reduced presynaptic dopamine synthesis could be a secondary consequence of increased autoregulatory feedback , potentiDopamine also has effects on neurodevelopment, influencing neuronal migration, neurite outgrowth and synapse formation , and theWe did not find evidence of a link between dlPFC volume and presynaptic striatal dopamine synthesis in the present sample. It is possible that measures of fronto-striatal connectivity may be more sensitive to detect the effects of prefrontal cortex on striatal dopamine transmission than volumes . AlternaThese results may have implications for cognitive function in people born preterm. While the current group of study participants were not cognitively impaired, cognitive deficits are commonly found in individuals born VPT, and are exacerbated following perinatal brain injury . Both loIn the present study, we did not find an association between striatal dopamine synthesis and several measures of executive function. An important limitation of this finding is that our battery of cognitive tests did not include a comprehensive assessment of working memory. Working memory is a particularly common deficit in children born with perinatal brain injury , and is Reduced dopamine synthesis capacity is also associated with substance dependence , major dWe recently found that individuals born very preterm experience elevated subclinical psychiatric symptoms across a broad range of symptom dimensions . Here, iIn contrast, dopamine synthesis capacity is increased in the majority of people with schizophrenia  and peopIn contrast to the increased dopamine synthesis capacity seen in most schizophrenia patients, those who develop schizophrenia-like psychoses following abuse of drugs , and thoOur finding that there are not marked alterations in dopamine synthesis capacity in the VPT-no diagnosed injury group is also important for the large numbers of people born preterm, as it indicates that the development of the dopamine system, or at least those aspects related to dopamine synthesis, is not disrupted long-term in the absence of macroscopic perinatal brain injury. The VPT-perinatal brain injury and VPT-no diagnosed injury groups in the present study also differed in gestational age, and birth weight, as these neonatal risk factors tend to co-occur . NonetheFrom a methodological perspective, it is possible that between-group differences in the accuracy of image registration may contribute to the apparent reduction in dopamine synthesis capacity seen in the VPT-perinatal brain injury group. However, we used the subject’s own MRI to define the PET region of interest which should mitigate, although not entirely avoid, this risk. Moreover, the results remained significant after controlling for both striatal and total intracranial volume or excluding subjects without MRI scans, suggesting that volume reductions or normalisation differences do not account for the findings. The postnatal ultrasound scans exclude macroscopic brain injury in the VPT-no diagnosed injury group but do not exclude a variety of other microscopic alterations. However, this would not explain our results, as it would, if anything, reduce group differences. Lastly, the final sample size for individuals with combined PET and MRI data of 13 individuals per group is not large. However, PET studies of presynaptic dopamine synthesis with clinical samples have consistently been able to detect group differences with group sizes of between 5 and 12 individuals . NonetheIn summary, we found reduced presynaptic dopamine synthesis capacity in the striatum in individuals born VPT with macroscopic perinatal brain injury. This may help to guide pharmacological interventions for cognitive deficits in this group. We additionally found significant associations between dopaminergic function and reduced hippocampal volume. These results indicate there are long-term neurochemical and structural consequences of perinatal brain injury.We assessed a group of individuals born VPT who were admitted to the Neonatal Unit of University College Hospital, London in 1979–1985. These individuals were enrolled in a longitudinal study and have been studied periodically for their entire lives.Macroscopic perinatal brain injury was qualitatively assessed in all participants born VPT and diagnosis of perinatal brain injury was made after consensus between at least two neuroradiologists with a special interest in neonatology. Hemorrhage into the germinal matrix, and those extending to the lateral ventricles or brain parenchyma was labeled as periventricular hemorrhage , with thParticipants who gave consent at previous study time-points to be contacted regarding the study were recruited using the contact details provided previously, and control participants were recruited via advertisements in the local community. Exclusion criteria for all groups were history of post-natal head injury, neurological condition  or significant physical illness (such as endocrine or metabolic disorder requiring treatment), substance dependence or abuse, psychotic disorder, current antipsychotic use, and pregnancy. The study was undertaken with the understanding and written informed consent and consent to publish of each subject, with the approval of the London Bentham Research Ethics Committee (Study 11/LO/0732), and in compliance with national legislation and the Code of Ethical Principles for Medical Research Involving Human Subjects of the World Medical Association (Declaration of Helsinki). Birth weight was recorded for all VPT participants and socio-economic status measured in all subjects using the Standard Occupational Classification .In adulthood, all participants underwent a 3,4-dihydroxy-6-[18F]-fluoro-/-phenylalanine ([18F]-DOPA) scan in a Biograph 6 PET/CT scanner with Truepoint gantry . Subjects were asked to fast from midnight and abstain from smoking tobacco and consuming food and liquids (except for buttered toast and water) from midnight before the day of imaging to ensure there were no group differences in amino acid consumption prior to the scan. On the day of the PET scan, a negative urinary drug screen was required and a negative pregnancy test was required in all female subjects. Subjects received carbidopa 150 mg and entacapone 400 mg orally 1 hr before imaging to reduce the formation of radiolabeled [18F]-DOPA metabolites . Head po3.On a separate day an MRI scan was performed on a 3 Tesla GE Signa MR scanner . T1-weighted images were acquired , allowing for 196 slices with no gap and an isotropic resolution of 1.1 × 1.1 × 1.1 mmTo correct for head movement, nonattenuation-corrected dynamic images were denoised using a level 2, order 64 Battle-Lemarie wavelet filter , and indAutomatic reconstruction of the hippocampus, caudate nucleus, putamen, nucleus accumbens and cerebellum was performed in the native space of each of the participants with MRI data, allowing for both individual masks and regional volume information extraction, using FreeSurfer version 5.1 . FreeSurA linear transformation was created between each participant’s T1-weighted structural scan and their individual PET image using FSL FLIRT . This trIn addition to the two participants  excluded from the PET study, four further participants  were not included in the MRI study due to contraindications to scanning. In order allow for the inclusion of these participants’ data in the PET analysis, we created a study-specific PET template using Advanced Normalization Tools (ANTs) . The temicer (min–1)], for each ROI using the Gjedde-Patlak graphic analysis adapted for a reference tissue input function   assessedTwo subtests from the Cambridge Neuropsychological Test Automated Battery (CANTAB)  were incAssessment of subclinical psychiatric symptoms was taken from a larger study  using thicer as the dependent variable, group as the independent variable and possible confounds  as covariates. Separately, in those participants born very preterm, we tested for the independent effects of three neonatal risk factors  on dopamine synthesis capacity in the whole striatum using an ANCOVA, with Kicer as the independent variable, group  as an independent variable and gestational age at birth and birth weight as covariates. In order to test for regional differences in the effect of VPT birth and perinatal brain injury on dopamine synthesis capacity , we performed a repeated-measures ANOVA with striatal subregion as the within-subjects factor, group as the between-subjects factor and Kicer as the dependent variable. To test for a hippocampal volume by striatal subregion interaction, we again performed a repeated-measures ANOVA, with subregion as the within-subject factor, hippocampal volume and intracranial volume as covariates and and Kicer as the dependent variable. To examine whether the relationship between hippocampal volume and striatal Kicer varied significantly by group, we used region as a within-subjects factor, with group and the group-by-hippocampal-volume interaction term as between-subjects factors. A two tailed p value<0.05 was taken as significant.ANOVA was used to test the primary hypotheses that there was an effect of group on whole striatal dopamine synthesis capacity and hippocampal volume. p-values from the ANOVAs were adjusted using FDR correction across striatal subregions (appropriate for positively correlated samples) . AdditioSCR_001622) and SPSS Version 23 (RRID:SCR_002865).In our exploratory analyses the following methods were used. To assess the relationship between dlPFC volume, hippocampal volume and striatal dopamine synthesis capacity, we used a general linear model, with dlPFC volume and hippocampal volume as dependent variables, and either caudate nucleus or nucleus accumbens dopamine synthesis as independent variables. The relationship between dopamine synthesis capacity and both executive function measures was assessed with Spearman correlations. Statistical analysis was performed in MATLAB 9.2 , is a member of our Board of Reviewing Editors, and the evaluation has been overseen by Sabine Kastner as the Senior Editor. The following individual involved in review of your submission has agreed to reveal their identity: Philip Corlett (Reviewer #2).Thank you for submitting your article "The effect of perinatal brain injury on dopaminergic function and hippocampal volume in adult life" for consideration by The reviewers have discussed the reviews with one another and the Reviewing Editor has drafted this decision to help you prepare a revised submission.Summary of manuscriptAnimal studies have shown that perinatal brain lesions, for example including the hippocampus, can induce long-term changes in dopaminergic transmission. This study examines whether a similar effect is found in humans with brain lesions acquired during the perinatal period. [18F]-DOPA positron emission tomography (PET) and structural MRI were used to compare three groups: adults who were born very preterm (VPT) with versus without perinatal brain injury and age-matched controls. The study finds that dopamine synthesis capacity was reduced in VPT adults with perinatal brain injury compared to the two other groups. Similarly, hippocampal volume was smaller in VPT adults with perinatal brain injury compared to the control group. Hippocampal volume and dopamine synthesis capacity were positively correlated.Summary of reviewsBoth reviewers agreed that the study was novel and important as it provides the first evidence in humans in favour of a relation between perinatal brain lesions and dopamine function. The main criticism, expressed by both reviewers, is that the interpretation of the results needs further thought and critical discussion, in particular with respect to the existing animal literature.The policy of the journal is to provide you with a single set of comments which reflect the consensus view amongst reviewers. These comments can be found below and are divided into essential or major issues, which must be addressed convincingly, and minor issues. We hope that you will find these comments helpful to further improve the paper.Essential revisions1) The finding of reduced DA synthesis capacity after perinatal brain injury is very interesting but is not easily reconciled with previous preclinical results. That is, the results of this study somewhat contradict findings that neonatal ventral hippocampal lesions can alter prefrontal neural function and increase dopamine synthesis capacity subcortically  and Meyer-Lindenberg ). While we do not consider this a fundamental problem, we do think any discrepancies should be identified clearly and discussed in more depth in the paper. At the moment, the reader may get the impression that inconsistencies are brushed under the carpet. For example, the statement in subsection “Cognitive Implications” …") is potentially misleading since the cited paper suggests increased (not decreased) DA transmission after experimentally induced hippocampal lesions. A more detailed discussion of these issues would further strengthen the paper. For example, there may be a difference between experimentally induced focal hippocampal lesions in animals and diffuse macroscopic injury in VPT human individuals, where hippocampal volume loss could represent a non-specific effect ?2) Did you examine the structural integrity of the dorsolateral prefrontal cortex (DLPFC) in the present sample? Could it mediate the link between changes in hippocampal volume and dopaminergic function? Essential revisions1) The finding of reduced DA synthesis capacity after perinatal brain injury is very interesting but is not easily reconciled with previous preclinical results. That is, the results of this study somewhat contradict findings that neonatal ventral hippocampal lesions can alter prefrontal neural function and increase dopamine synthesis capacity subcortically  and Meyer-Lindenberg ). While we do not consider this a fundamental problem, we do think any discrepancies should be identified clearly and discussed in more depth in the paper. At the moment, the reader may get the impression that inconsistencies are brushed under the carpet. For example, the statement in subsection “Cognitive Implications” …") is potentially misleading since the cited paper suggests increased (not decreased) DA transmission after experimentally induced hippocampal lesions. A more detailed discussion of these issues would further strengthen the paper. For example, there may be a difference between experimentally induced focal hippocampal lesions in animals and diffuse macroscopic injury in VPT human individuals, where hippocampal volume loss could represent a non-specific effect ?We thank the reviewers for their insightful and helpful comments on the manuscript.We agree that the relationship between the present study and related preclinical studies requires further discussion. Several preclinical models involving similar designs, such as the MAM model, and the adult ventral hippocampal lesion lead to increased striatal dopamine release and behavioral effects including hyperresponsiveness to stress and amphetamine. Interestingly, while the neonatal ventral hippocampal lesion model leads to similar behavioural effects, there appears to be little evidence of an increase in presynaptic striatal dopamine synthesis or increased release. Increased sensitivity of postsynaptic dopamine D2 receptors may reconcile the discordant neurobiological and behavioural results, and suggests a hypothesis to test in future studies, that could explain the increased risk of psychosis in adulthood for individuals born very preterm and those with perinatal brain injury.We have amended the Introduction and Discussion as follows:Introduction:“Several animal models of schizophrenia have linked hippocampal lesions at different life stages to altered dopaminergic function.[…] In contrast, both adult hippocampal lesions and pre-natal injection of the mitotoxin methylazoxymethanol acetate (MAM) into the ventral hippocampus lead to similar behavioural effects and increased presynaptic dopaminergic activity .”Discussion;“Several preclinical models, including the MAM model  and adult hippocampal lesions , have linked hippocampal damage to increased striatal dopaminergic synthesis and release, and behavioral effects including hyperresponsiveness to stress and amphetamine, which are traditionally associated with hyperdopaminergia . […] Whether increased postsynaptic D2 receptor sensitivity or increased synaptic dopamine levels are seen in humans born very preterm should be tested in further studies.”2) Did you examine the structural integrity of the dorsolateral prefrontal cortex (DLPFC) in the present sample? Could it mediate the link between changes in hippocampal volume and dopaminergic function?We have now included an analysis of dlPFC volume , taken from a recent study in an overlapping sample .We have included the following statement in the Introduction:“In rodents, neonatal hippocampal lesions lead to disrupted development of the prefrontal cortex . We have previously demonstrated structural and functional cortico-striatal connectivity alterations following very preterm birth , which could have significant effects on dopamine transmission .”Results:“There were no statistically significant differences between the control group and both VPT groups in dorsolateral prefrontal cortex volume .”“Dorsolateral Prefrontal Cortex and Dopamine SynthesisWe recently conducted a large-scale structural analysis in an overlapping sample. In that study, we found evidence of accelerated maturation of the prefrontal cortex, and slower maturation of the caudate nucleus in adults born very preterm. […] In this caudate model, the hippocampal volume was still a significant predictor of dopamine synthesis capacity , but dlPFC volume was not . This was also the case when using relative, instead of raw dlPFC volumes . In the nucleus accumbens model, neither the hippocampus  nor the dlPFC  significantly predicted dopamine synthesis. Again, using relative dlPFC volumes did not alter the result .”Discussion:“Dorsolateral prefrontal cortex and striatal dopamineWe did not find evidence of a link between dorsolateral prefrontal cortex volume and presynaptic striatal dopamine synthesis in the present sample. […] Alternatively, other striatal dopaminergic mechanisms, such as dopamine release, may be more directly affected by prefrontal input to the striatum . “Materials and methods:“Dorsolateral Prefrontal Cortex VolumesRelative and absolute volumes of the dorsolateral prefrontal cortex were taken from a recent large scale study of volumetric alterations following preterm birth . […] We analysed both raw dorsolateral prefrontal cortex volume, and relative volume .”“To assess the relationship between dorsolateral prefrontal cortex volume, hippocampal volume and striatal dopamine synthesis capacity, we used a general linear model, with dorsolateral prefrontal cortex volume and hippocampal volume as dependent variables, and either caudate nucleus or nucleus accumbens dopamine synthesis as independent variables.”


Myelinating glia of the nervous system are in extraordinary high demand for lipids which are required to form the multi-layered membranous myelin sheaths that enwrap and insulate axons, allowing and refining efficient neuronal impulse propagation. This reliance is highlighted by various myelin pathologies that are observed in several diseases affecting lipid metabolism [Various lipids are essential constituents of diverse biological membranes. With the exception of cholesterol, such membrane lipids share the use of fatty acids as building blocks. Besides structural functions, fatty acids and the derived lipids are also involved in other central biological processes, such as providing an important energy source, acting as signaling molecules, being modulators of gene regulation, and generating post-translational modifications of proteins . Howevertabolism . In parttabolism . This catabolism . Neverthtabolism . This prde novo lipid synthesis in Schwann cells of genetically modified mice caused a partial block in the onset of myelination. Further analyses revealed that lipogenic activation of the transcriptional network regulated by the transcription factor PPARγ contributes to driving the initiation of myelination [We found recently that FASN plays an essential role in Schwann cells, the myelinating glia of the peripheral nervous system . Lack oflination . HoweverIn our experimental setting, some Schwann cells still managed to start myelination in the absence of FASN. Why would this occur? Our findings suggest that one answer may lie in the relative localization of these cells in the tissue, more specifically in their proximity to blood vessels as a source for fatty acid uptake. Whether these observations reflect a regulated compensatory mechanism remains to be clarified. In addition, we found that adipocytes associated with peripheral nerves responded to a lack of fatty acid synthesis in Schwann cells by undergoing lipolysis suggesting another potential compensatory reaction . We specRemarkably, increasing dietary intake of fatty acids by putting the mutant mice on a high-fat diet did not ameliorate the observed impaired myelination. Instead, this treatment resulted in worsening of the phenotype in nerves of mutant mice, although no effect was observed in nerves of control mice . Furtherde novo fatty acid synthesis and fatty acid-based regulation in establishing and refining suitable connectivity in the central nervous system remain a major task for the future [Many questions remain open in the context of our study. Most closely related, the detailed roles of e future .


With the expansion of the nanomedicine field, the knowledge focusing on the behavior of nanoparticles in the biological milieu has rapidly escalated. Upon introduction to a complex biological system, nanomaterials dynamically interact with all the encountered biomolecules and form the protein “bio-corona.” The decoration with these surface biomolecules endows nanoparticles with new properties. The present review will address updates of the protein bio-corona characteristics as influenced by nanoparticle’s physicochemical properties and by the particularities of the encountered biological milieu. Undeniably, bio-corona generation influences the efficacy of the nanodrug and guides the actions of innate and adaptive immunity. Exploiting the dynamic process of protein bio-corona development in combination with the new engineered horizons of drugs linked to nanoparticles could lead to innovative functional nanotherapies. Therefore, bio-medical nanotechnologies should focus on the interactions of nanoparticles with the immune system for both safety and efficacy reasons. The evolvement of the immune system during human’s phylogeny and ontogeny was accomplished through exposure to different chemical, physical and biological agents. All the immune mechanisms have been adapting to human environments through the course of history Danilova . Thus, tWhen aggressors reach the organism, the first defense layer is the physical barrier that is constituted by skin and mucosae. These layers can make use of constitutive defense weapons like cutaneous/mucosal secretion, reflexes like nociceptive reflexes or defensive vomiting to rapidly get rid of any harmful aggressors. When this barrier is breached, pathogens or injuries that threaten the body homeostasis are subjected to the action of the immune system. Two different branches of the immune system work together to restore homeostasis: the innate and adaptive immune systems. These sentinels monitor vertebrate tissues and use different tactics to recognize and overcome threats. These two branches are inherently different as regarding the sensors and mechanisms employed in order to provide either immediate protection with broad specificity (innate immunity) or delayed and prolonged protection with exquisite specificity (adaptive immunity). Furthermore, the two branches must effectively coordinate a response and physiologically down-regulate its intensity in order to prevent excessive or inappropriately targeted inflammation Janeway .During our evolution, as humans we were exposed to food and environmental particles, a myriad of them being in the nanoparticle ranges. Airborne nanoparticles have cohabitated with humans throughout the evolutionary process, but the exposure has significantly increased in the last 100 years owing to industrial revolution  can reach intra-cellular structures that were previously accessible only to biological aggressors. On the other hand, NPs reaching subcellular structures can be therapeutics in the rapidly evolving nanomedicine field, where applications rely on nanoscale interactions. This concept, however, is not so simple as in biological milieu, NPs interact with molecules that will completely alter their initial chemical structure  nature. Noteworthy, ECM constituents interact with cell surface receptors, growth factors and cytokines, leading to numerous signaling cascades which are closely related to cell behavior , immunoglobulin (IgG) and fibrinogen were found to be the major hard corona proteins binding firmly on to the NP surfaces and showing distinctive stability , it stands to reason that protein corona formation should depend on physical and chemical characteristics of both NPs and their biological surroundings  under conditions of similar surface charge, titanium and silicon dioxide NPs adsorb related proteins  which differ considerably from those adsorbed by zinc oxide NPs   and reduce protein binding. By inhibiting the generation of the biomolecular corona, a remarkably rapid transport of NPs across the endothelium can be achieved. One added advantage of this approach is the possibility to control PEG density on NP surface, allowing for longer circulation in the blood stream. Alternatively to PEG, silicon may also be used as a coating agent, exhibiting the same beneficial effect on protein adsorption  was treated with 15-nm gold NPs in both DMEM and RPMI media, and in continuation, various viability assays were performed. This approach revealed substantial differences in cellular uptake, dynamics and NP–protein complexes bio-distribution. Thus, in RPMI-cultured cells, NP–protein complexes were internalized to a markedly higher extent as compared to DMEM-cultured cells, leading to enhanced cytotoxic effects. Furthermore, RPMI-induced protein corona was inferior in abundance and stability compared to the protein corona formed in the DMEM culture  using pattern recognition receptors. The immune system also responds to the altered self, namely to tissue damage, a process triggered by the so-called danger- or damage-associated molecular patterns (DAMPs) or “alarmins” Fadeel  Fig. 2)2).Fig. 2driving force is the need to detect and protect against danger focusing more on endogenous than on exogenous signals. The cues represent the alarm signal that originates from an injured tissue , fibrinogen interacted with TiO2 and CeO2 NPs with high affinity, while with Al2O3, the affinity was low and in an 1:1 ratio type. In contrast, HSA interacted with TiO2, CeO2 and Al2O3 NPs with low affinity according to a conformational change model. Moreover, fibrinogen associated faster with NPs, while HSA exhibited a lower association pattern  bind to copolymer NPs with much higher affinity than other lipoproteins, probably mediated by apolipoprotein A-I, which is its major component. In brief, together with the alternate protein-binding patterns in the corona, copolymer NPs bind complete HDL complexes and may be recognized by living systems as HDL complexes . Current research in the field of nanomedicine is focused on how modulating the formation of bio-corona in complex biological environments can result in obtaining more targeted nanodrugs and in decreasing rapid recognition by mononuclear phagocyte system (MPS) and the elimination of the NPs from the body.Nanomedicine applications together with nanopharmaceutics benefit from the rapidly advancing nanotechnology. Nanomedicine research and state-of-the-art advances in nanobiotechnology are closely linked. Research advances have brought high-tech nanoscale measurement that has facilitated the investigation of cellular biological processes; these investigations open the door for nanomedicine  prior to intravenous injection. This coating influences the bio-corona formation and the NP bio-kinetics. Albumin NPs exhibited increased accumulation in lungs, spleen and brain in comparison with the control cit-AuNP. Protein conjugation reduces also liver retention  (PLGA) containing antigen, plus ligands that activate TLR4 and TLR7 can induce higher titers of antigen-specific, neutralizing antibodies compared to immunization with NPs specific for just one TLR. This model proved its usefulness in protecting against lethal avian and swine influenza virus strains. This vaccination type was also tested in non-human primates that show a different TLR7 expression on DCs as we compared to murine strains (Kasturi et al. Another application with good future perspectives is vaccination. We have discussed in the previous sections that nanomaterials interact with innate immune cells through TLRs but as well as with other immune molecular systems such as the complement system. Nanomaterials that carry the complex bio-corona can activate the inflammasome in macrophages leading to pro-inflammatory cytokines cascade. Importantly, these findings can be manipulated in developing novel classes of immunostimulatory agents (Hubbell et al. It is well established that certain small molecules, non-immunogenic haptens, can elicit an immune response when coupled to a protein carrier (Boraschi et al. Several aspects within this section were touched upon in the previous sections, but some final highlights of the toxicological aspects that are raised by the protein bio-corona need to be resolved. Due to NPs’ physical characteristics and high surface area–volume ratio, there remain unknown toxicity mechanisms within the biological systems that remain to be unraveled (Oberdorster As indicated above, the bio-corona is a dynamic entity and the toxicological impact of it needs to be determined by unveiling toxicologically relevant phenomena at the nano-bio-interface (Westmeier et al. Understanding the complex interaction of NPs with the biological microenvironments of the host organism and the resulting biological actions is one of the goals of nanotoxicology and the nanomedicine field. All the physicochemical properties that characterize NPs alter the immune interactions. Specific adsorption of biomolecules bestows onto the NP a new immunological identity Fadeel . UnderstPinpointing individual nanomaterial characteristics (Fadeel et al.


Orthostatic challenge produced by upright posture may lead to syncope if the cardiovascular system is unable to maintain adequate brain perfusion. This review outlines orthostatic intolerance related to the aging process, long-term bedrest confinement, drugs, and disease. Aging-associated illness or injury due to falls often leads to hospitalization. Older patients spend up to 83% of hospital admission lying in bed and thus the consequences of bedrest confinement such as physiological deconditioning, functional decline, and orthostatic intolerance represent a central challenge in the care of the vulnerable older population. This review examines current scientific knowledge regarding orthostatic intolerance and how it comes about and provides a framework for understanding of (patho-) physiological concepts of cardiovascular (in-) stability in ambulatory and bedrest confined senior citizens as well as in individuals with disease conditions  or those on multiple medications (polypharmacy). Understanding these aspects, along with cardio-postural interactions, is particularly important as blood pressure destabilization leading to orthostatic intolerance affects 3–4% of the general population, and in 4 out of 10 cases the exact cause remains elusive. Reviewed also are countermeasures to orthostatic intolerance such as exercise, water drinking, mental arithmetic, cognitive training, and respiration training in SCI patients. We speculate that optimally applied countermeasures such as mental challenge maintain sympathetic activity, and improve venous return, stroke volume, and consequently, blood pressure during upright standing. Finally, this paper emphasizes the importance of an active life style in old age and why early re-mobilization following bedrest confinement or bedrest is crucial in preventing orthostatic intolerance, falls and falls-related injuries in older persons. In most persons, the hemodynamic and neurovascular responses to orthostatic challenge produced by standing up are adequate to stabilize arterial blood pressure and to maintain cerebral blood flow after standing. However, numerous patients come to clinics with the complaint of dizziness upon standing  leading to increasing public health costs as well as costs for older people and their families. The negative consequences of aging such as illness or injury often require admission to hospital. However, the bedrest confinement that occurs during hospitalization is considered a major factor in physiological deconditioning and functional decline and can contribute to a downhill spiral of increasing risk of frailty, and orthostatic intolerance, leading to falls  position, the hemodynamic responses may not be enough to sustain the arterial blood pressure, and syncope may ensue. In a healthy person, upon standing up, 10–15% (~700 mL) of blood volume can pool due to gravitational effects in the legs  to naturally optimize body positioning  was observed, a new physiological model—Recently, Rodriguez et al.  reportedOrthostatic hypotension is common in older adults. The prevalence of asymptomatic orthostatic hypotension  in 5,201 randomly selected persons aged 65 and older with natural history of—or with risk factors for—cerebrovascular or cardiovascular diseases was found to be 16.2% , and after taking into account all the confounders, orthostatic hypotension risk was found to be 64% higher in summer  is the arbitrary decrease in systolic BP ≥ 20 mmHg or postprandial reduction in systolic BP to <90 mmHg within 2 h following a meal  show blood pressure reducing effect , who were free from coronary heart disease or heart failure and participating in a general health checkup. A higher prevalence of cerebral lacunar infarctions as evidenced by MRI was shown in subjects with postprandial hypotension compared with controls , concussion and long term bedrest itself. Orthostatic intolerance can also arise in patients with stroke  signaling, resulting in constant sympathetic activity, which over time can increase resistance at adrenergic beta-receptors to stimulation or there may be a greater inhibition of sympathetic catecholamine release. Patients with hypertension, stroke, and chronic heart disease often display this type of reactivity and the Rodriguez et al. . Following exercise it was observed that MAP decreased in patients with cervical SCI (−9.3 ± 2 mmHg) but increased in thoracic SCI . They suggested that these effects might partially arise due to the loss of descending sympathetic nervous control of the heart and vasculature, which accompanies SCI of higher levels. However, these data were obtained from a sample of younger persons. Therefore, interpretations in terms of effects of exercise in older people with SCI must be applied with caution.OH that accompanies SCI can also complicate a patient's participation in rehabilitation, especially when carrying out exercises conditioning, muscle loss, cardiovascular and vestibular effects, is followed. Such an approach will lead to more effective management of bedrest confinement, reduced orthostatic intolerance and falls and falls-related injury, and consequently decrease public health costs, costs for older people and their families as well as decrease secondary care dependency.Outlined below are some of the possible countermeasures that are currently in use or being examined. While not all of these interventions have been tested in older persons, we present here some evidence that these countermeasures can reduce orthostatic intolerance in young and middle aged persons.Physical exercise is therapeutic for many medical disorders  fail to even maintain calf muscle strength and size under bedrest conditions  are still lacking for hospitalized older people. As a result, in many hospitals, the acute care of older persons does not incorporate procedures to promote remobilization early enough. Physical exercise interventions are often delayed and the procedures implemented may be based on individual therapist experience leading to non-standardized interventions which are often only applied after substantial loss of muscle mass and function has occurred. Thus patients may be discharged without recovering sufficient physical function leading to a vicious circle of hospital deconditioning leading to injury and further hospitalization and further dependency (Singh et al., The responses to water consumption in young healthy persons are complex with a simultaneous increase in vagal tone, as evidenced by bradycardia and an increase in the high-frequency component of the HRV, and some vasoconstriction, as evidenced by a rise in peripheral resistance (Brown et al., In older persons, the effects of water drinking has been sparsely studied. However, one study has clearly shown that drinking half a liter of water leads to acute increases in blood pressure also in older subjects (Jordan et al., Mental challenge increases heart rate, cardiac output, force of cardiac contraction, and blood pressure (Lackner et al., In a pilot study, Goswami et al.  have shoMental challenge-induced increases in sympathetic activity also affect the venous system. As 70% of total blood volume is approximately in the venous system, and veins are strongly controlled by the sympathetic system (reviewed in Pang, The responses to mental challenge conducted in upright position are unsurprising, as mental challenge induced central drive modulates physiological responses (e.g., cardiovascular reflexes, Ross and Steptoe, Mental arithmetic, Stroop color-word conflict, and public speaking are commonly used mental stressors (Steptoe and Vogele, exact timing of the application. Lackner et al. (Goswami et al.  propose r et al.  have repr et al. . For insr et al. . As longr et al.  recommenStanding up slowly in older persons with histories of orthostatic hypotension has been shown to antagonize the blood pressure decreases within the first 15 sec of changes in posture/ standing (de Bruïne et al., Some other countermeasures that could potentially prevent orthostatic intolerance include standing up slowly (de Bruïne et al., Recent evidence also suggests that cognitive training (Goswami et al., The concept of using cognitive training as a countermeasure in preventing functional decline originates from the observations that cognitive interventions promote functional outcomes, particularly improvements in mobility in older sedentary persons (Verghese et al., Finally, as mental challenge causes increased blood flow in skeletal muscles (Kuipers et al., −1 · d−1 provided by red lean meat has been shown to improve the effects of progressive resistant training on lean tissue mass and muscle strength in older women (Daly et al., Nutritional therapy, along with resistance training affects muscle mass in healthy older adults (Strandberg et al., Inspiratory-expiratory pressure threshold respiratory training has recently been shown to reduce the incidence of orthostatic hypotension in more than 50% of patients with SCI (Aslan et al., This review outlines orthostatic intolerance connected to age, bedrest confinement, and diseases. Aging-associated illness or injury due to falls often leads to hospitalization. As older patients spend significant amounts of time during hospital admission lying in bed, the consequences of bedrest confinement such as physiological deconditioning, functional decline, and orthostatic intolerance represent a central challenge in the care of the vulnerable older population.timing of the countermeasure application is also considered. Finally, this paper emphasizes the importance of an active life style in old age and why early re-mobilization following bedrest confinement is crucial in preventing orthostatic intolerance, falls and falls-related injuries in older persons.The review also discusses contributing mechanisms of orthostatic intolerance and examines countermeasures such as exercise, water drinking, and mental arithmetic. The There is a need to integrate cerebrovascular and cardiovascular variables into a combined analysis to allow for the development of improved orthostatic intolerance and fall risk-screening monitoring in older persons. Hand held devices for the analysis of global HRV (a key aspect for monitoring autonomic function (Grote et al., Additionally, rehabilitation post-stroke could benefit from combination of mobile monitoring of the autonomic and cardiovascular systems with effective physical therapy interventions to ensure that older persons are protected from muscle wasting and muscle loss after stroke. Future sit-to-stand protocols that include MSNA evaluation, by which the magnitude and timing of sympathetic responses could be measured, could be carried out to clarify the relationship between MSNA and HRV. All these aspects are important in the asssement of orthostatic intolerance risk in patients during hospitalization and upon discharge.Finally, there is a need to implement more integrated screening procedures during hospital admission to personalize countermeasures against orthostatic intolerance, which can arise due to bedrest confinement.NG conceived the idea and wrote the manuscript. AB supported in editing the manuscript and contributed to sections related to cardio-postural interactions. HH-S helped in writing the manuscript. J-PM supported in editing the manuscript and contributed to sections related to water drinking as well as post-prandial hypotension.The section related to mental stress is based on the Doctoral work of NG. The other authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Feline allergic skin disease presents a unique set of challenges to the veterinary practitioner. Although there is some similarity to what is seen in the allergic canine patient, cutaneous hypersensitivity dermatoses in cats can manifest with strikingly different clinical signs, treatment options and outcomes, and secondary complications/disease entities. Additionally, less is known about the pathogenesis of feline allergic skin diseases, particularly “feline atopic syndrome” when compared to dogs or people. This article aims to review what is currently known in regards to allergic skin disease in the feline patient, with focus on non-flea, non-food hypersensitivity dermatitis. Although it is often noted throughout the veterinary profession that cats are not small dogs, this fact becomes particularly apparent with regards to the manifestation of feline dermatological abnormalities. Cats present a unique clinical entity in terms of their manifestation of inflammatory skin disease, particularly the cutaneous hypersensitivity dermatoses. Frequently, the allergic feline patient will present with at least one of the four common cutaneous reaction patterns indicative of pruritus and inflammation: head/neck/pinnal pruritus with excoriations, self-induced alopecia, miliary dermatitis, and/or eosinophilic lesions  . The reaAs with dogs, hypersensitivity skin diseases in cats fall into three main categories; however, the nomenclature is a bit different. Flea (and other insect bite) bite hypersensitivity and food induced hypersensitivity dermatitis (cutaneous adverse food reaction) are similar between dogs and cats, but atopic dermatitis is where the two species separate. Due to the lack of conclusively demonstrated influence of IgE (immunoglobulin E) on disease pathogenesis , the terFlea allergy dermatitis (FAD) has historically been considered the most frequently diagnosed hypersensitivity condition in the cat . ClassicAs in the dog, flea bite hypersensitivity reflects a type I (immediate-type) and/or type IV (delayed-type) hypersensitivity reaction in the cat . IntradeA somewhat closely related hypersensitivity condition in the feline patient is mosquito bite hypersensitivity. Also a type I (immediate-type) hypersensitivity reaction, mosquito bite hypersensitivity shares several features with FAD. The most common lesion reported is miliary dermatitis; eosinophils are rather easily demonstrated on lesions of affected cats. Head, neck and pinnal pruritus are commonly reported as lesions often concentrate along the convex surface of the pinnae as well as along the bridge of the nose. Paw pads may occasionally be implicated in disease presentation as well . While lThe mainstay of therapy involves avoidance as much as possible. Ideally, affected cats should be kept indoor where mosquito exposure is decreased. It is important to note that many insect repellents designed for humans are not safe to use on cats . Permethrin-based products should also be avoided due to toxicity seen in the feline species . The newToxoplasma gondii, lending concern for the role of endoparasitism in the development of food induced hypersensitivity dermatitis [In a cat with non-seasonal pruritus, and where parasitic and infectious causes of pruritus have been ruled out, food induced hypersensitivity dermatitis should be a considered differential diagnosis. Although information sources disagree on the prevalence of cutaneous reactions to food in the feline patient, with incidence ranging from 1% to 6% of all feline dermatological abnormalities , most sormatitis . The invrmatitis  may alsoNon-seasonal pruritus is the hallmark of feline food hypersensitivity. The condition presents similarly to NFNFHD in the cat in that one or more cutaneous reaction patterns may be noted. Although other body regions may be affected and the pruritus may be considered generalized in some cats, several reports identify pruritus as often disproportionally severe and more commonly involving the head, neck, and pinnae in cats with CAFR ,16. ConcPrior to investigating CAFR in the feline patient, parasitic and infectious causes of pruritus should be ruled out. Additionally, adulticidal flea prevention should be instituted to address sole or concurrent FAD. With regards to testing for food sensitivity, the only accurate way to diagnose the condition is with a strict elimination diet trial followed by a provocative food trial to confirm the food sensitivity. Without dietary challenge following improvement with a novel protein or hydrolyzed diet, food sensitivity can only be presumed. Serum allergy testing for IgE antibodies and intradermal testing with food allergens has been investigated in both dogs and people; both tests have been shown to be inaccurate and insensitive in the dog ,21. AlthAs with dogs, the length recommended for the hypoallergenic diet trial and dietary choice varies among veterinary dermatologists. Evidence based review of several sources found that more than 80% of cats with CAFR showed improvement with dietary manipulation within 6 weeks, however extending the diet trial to 8 weeks lead to complete remission in approximately 90% of cats and dogs with food sensitivity . WhetherThe term “feline atopy” was first introduced into the veterinary literature in 1982 . The desWith regards to the pathogenesis surrounding NFNFHD in cats, the disease does share some similarities to both human and canine AD. Although less well described in cats, genetic influence of disease development does seem possible as is true for dogs and people . ExposurClinical signs of NFNFHD in cats revolve around the presence of pruritus. Lesion/pruritus distribution may include any one or more of the four cutaneous reaction patterns. As NFNFHD is a diagnosis of exclusion, as is true for AD in dogs and other species, ruling out parasites, infections, and other allergic diseases  is imperative. In dogs and people, concurrent bacterial pyoderma secondary to underlying AD is considered to be a very common finding. The role of staphylococcal infections with regards to epidermal barrier function and the pathogenesis of AD in people has been well evaluated for several years; findings from various studies have changed the overall understanding of the disease and focus of therapeutic recommendations . As dogsAs with bacterial pyoderma, Malassezia species overgrowth is considered to be a common concurrent finding in dogs and people with AD. Historically, secondary Malassezia overgrowth in feline patients with allergic skin disease has only been reported anecdotally. More frequently, Malassezia overgrowth was noted in cats with systemic illnesses including thymoma-associated dermatitis, paraneoplastic alopecia , and catAlong with the cutaneous reactions patterns noted in cats with NFNFHD, other non-cutaneous clinical signs may be concurrently present. This may include allergic otitis, sinusitis, and conjunctivitis  as well Although pinnal pruritus is a fairly common manifestation of feline NFNFHD, the ear canals themselves are frequently normal in appearance. This is in contrast to atopic dogs who frequently present with erythematous otitis externa secondary to allergic disease . Some caSneezing may be a frequent concurrent clinical sign in cats with NFNFHD which may be indicative of sinusitis. Some sources cite prevalence in up to 50% of cats with NFNFHD . As wellFeline small-airway disease or feline asthma is a complex syndrome; however, many cats have an allergic pathogenesis . A pilotAs with AD in other species, there is no cure for NFNFHD in cats. Rather, the goal of managing the disease relies on decreasing the severity and frequency of pruritic flares along with other cutaneous and non-cutaneous complications. Care should be taken to identify and manage any secondary disease entities such as parasites and infections as this will compound the degree of pruritus appreciated. Additionally, any other flare factors should be recognized and addressed.®, Elanco) is recommended in veterinary species due to more predictable absorption and bioavailability [®, Zoetis), a Janus kinase inhibitor labeled for the treatment of allergic pruritus and AD in dogs, has shown efficacy in reducing clinical signs in a small population of cats with NFNFHD [®, Zoetis) for the management of canine AD is not recommended for cats due to the likelihood of severe adverse reactions to the foreign protein [Various therapeutic entities are available for managing feline NFNFHD. As no one specific treatment may be ideal, each option should be carefully evaluated for each feline patient. Medical therapeutic treatments to address the signs and symptoms associated with feline NFNFHD can be broken into conservative options and more aggressive medical therapy. Conservative treatment options include fatty acid supplementation and antihistamines . More aglability . Oclacith NFNFHD . This me protein . Allerge protein . Various protein . It is iCutaneous hypersensitivity diseases in cats, while showing parallels to the similar allergic diseases in dogs, presents with several differences in regards to clinical signs, pathogenesis, and specific treatment recommendations. As with dogs, it is important to identify and address secondary complications of pruritus including ectoparasites and infections prior to embarking down the journey of working up the allergic feline patient. Imperative to keep in mind is that concurrent allergic diseases may present in the same patient. Addressing flea bite hypersensitivity and other insect allergies as well as food allergy prior to evaluating non-flea, non-food hypersensitivity dermatitis is key to successful disease control. Once a diagnosis of NFNFHD is reached, continuously assessing the presence of secondary complications and flare factors as well as evaluating options and differences in therapeutic recommendations will lead to improved patient care and disease management.