Impaired brain connectivity is a hallmark of schizophrenia brain dysfunction. However, the effect of drug treatment and challenges on the dysconnectivity of functional networks in schizophrenia is an understudied area. In this review, we provide an overview of functional magnetic resonance imaging studies examining dysconnectivity in schizophrenia and discuss the few studies which have also attempted to probe connectivity changes with antipsychotic drug treatment. We conclude with a discussion of possible avenues for further investigation. Schizophrenia is a severe and heterogeneous brain disease with onset usually in late adolescence or early adulthood. Symptoms are typically classified as positive  or negative  . Also, cFunctional neuroimaging has been widely used to pinpoint the neural mechanisms underlying the core symptoms of schizophrenia. Early neuroimaging studies have tried to identify abnormal task-related activation patterns in localised brain areas that may underlie the symptoms of schizophrenia . A parti1a). However, antipsychotic medications, most with complex receptor binding profiles, all share an affinity for the D2 receptor. There is recent meta-analytical evidence indicating a 14% increase of striatal presynaptic dopaminergic neurotransmission in schizophrenia patients as compared to controls [2 receptor binding potentials [1 to D2 receptor signalling has been implicated in the manifestation of positive as well as negative and cognitive symptoms in schizophrenia [2 antagonism, the first generation of antipsychotics (FGAs) produced extrapyramidal side effects. However, second generation antipsychotics (SGAs) generally have a therapeutic effect at doses with lower striatal D2 receptor blockade and therefore produce less extrapyramidal side effects. It was initially proposed that SGAs would be superior in targeting negative symptoms and cognitive deficits. The beneficial effect on negative and cognitive symptoms was thought to be mediated by an antagonistic effect of some SGAs on serotoninergic neurotransmission [2 antagonism might thus improve cognitive deficits by restoring the D2:D1 receptor signalling ratio which has been proposed to be integral for efficient cognitive processing of external stimuli [The circuits thought to be involved in schizophrenia are complex, involving various neurotransmitters and receptors at the cortical and subcortical levels  interneurons, can further weaken cortical glutamatergic transmission [2 receptors might therefore promote more efficient connectivity between subcortical and cortical regions. Indeed, animal models of schizophrenia have revealed that pharmacologically-induced cortical desynchronisation can be reversed by FGAs and SGAs [A focus on ‘localisation of dysfunction’ has been replaced in recent years by an ‘impaired connectivity’ perspective which postulates that impaired functional interactions between brain regions, rather than changes in regional neuronal activity of specific cortical areas, underlie the dysfunction associated with schizophrenia , 41. Dyssmission , 47. Sucand SGAs -51. Numerous neuroimaging studies in humans have provided convergent evidence that in schizophrenia, functional brain networks express abnormal connectivity patterns both at rest and during experimental tasks , 52-56. Functional neuroimaging with positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) techniques can be used to study whole-brain functional and effective connectivity in schizophrenia. In recent years, fMRI has gained popularity over PET imaging as it is the less expensive and invasive choice of the two. Most fMRI connectivity studies use the blood oxygen level dependent (BOLD) signal as a neurovascular index of regional synaptic activity . BOLD fMBrain imaging studies have also employed methods which capture the distributed patterns of neural activity in brain networks rather than the coupling of activity changes in focal regions. Much of this work, but not all, is based on data collected while participants are at rest. Resting state networks have been found replicable across subjects and over time, and spatially overlap networks which are found in activation studies so therefore seem functionally meaningful . Multiva1b). Based on these considerations, we comment on future perspectives for neuroimaging research to unravel the impact of pharmacological interventions on impaired connectivity in schizophrenia. Although abnormal brain connectivity has been emphasised as a critical aspect of the pathophysiology of schizophrenia, only a few pharmacological neuroimaging studies have concentrated on the functional impact of psychopharmacological treatment on brain connectivity in patients with schizophrenia. This is surprising as pharmacologically-induced increases or decreases in regional neural activity do not necessarily imply that dysconnectivity has also been ameliorated. Here we will review the potential effect of antipsychotic medications on the brain connectivity of patients affected with psychosis. In order to review the literature, we will summarise abnormal connectivity patterns which, where available, have been identified in samples minimally affected by medication . We will summarise dysconnectivity of local circuits as well as distributed or topological differences in schizophrenia patients and relate these findings to reports of changes in connectivity induced by pharmacological challenges or interventions , although it attenuated neural network response to task in control subjects (n=12). Behaviourally, flumazenil also improved task performance in the patient group but worsened it in the control group (thereby decreasing between-group performance differences).The increased functional coupling of the medial prefrontal regions and the default mode network might be modulated by antipsychotic medication. Indeed, a longitudinal fMRI study using a working memory task at four and eight weeks of olanzapine treatment found that prolonged treatment with olanzapine strengthened functional connectivity between ventromedial prefrontal cortex and the default mode network, but did not affect the connectivity strength of the posterior regions which had displayed altered connectivity with the default mode network in patients compared to healthy control subjects . Greatersubjects . FlumazeHowever, the neuroimaging data on the effects of antipsychotic treatment on functional activity and connectivity in the default mode network is heterogeneous. For instance, it was shown that patients with schizophrenia still exhibited attenuated task-suppression of the medial prefrontal cortex during working memory despite being medicated and despite displaying increased connectivity to the rest of the default mode network compared to controls and unaffected relatives . Another1c) [2 receptor antagonist [et al. [Distributed patterns of functional brain connectivity have also been examined using measures which characterise each node in brain networks in relation to other network nodes. For instance, topological features of brain connectivity can be described with graph theory by estimating the number of connections a node has or the length one node takes to reach another which determines how costly a network is to maintain and use  . It has 1c) . Graph t1c) -126 as w1c) . This ha1c) . Effectstagonist . In one tagonist . But, as [et al.  have poi1 for a summary) and the modulatory effects of antipsychotic drug treatment on functional connectivity of subcortico-cortical circuits and whole-brain functional topology remain to be thoroughly investigated. Other aspects of drug-induced changes in functional brain connectivity, for example, the drug effects on cerebellar-cortical, fronto-temporal, and fronto-parietal local circuits have so far only been rudimentarily explored.Connectivity differences between patients with schizophrenia and healthy control subjects seem to be widespread and involving many of the interactions that are important for efficient information processing. However, the bulk of the neuroimaging literature in schizophrenia is merely observational, assessing brain activity and connectivity many years after the neurodevelopmental changes that lead to the illness-onset. Longitudinal neuroimaging research of high-risk populations is therefore warranted to identify causal relationships between brain connectivity, illness, and treatment. The published studies on longitudinal changes in brain connectivity before and after antipsychotic treatment are very few and some suffer from small sample sizes , the emotional and cognitive processes activated by a given task, differences in task performance between patients and control subjects , and theThere is also a need for studies to determine the causal relationship between inter-connected regions. Due to its poor temporal resolution, causal relationships can be difficult to assess with fMRI. The combination of EEG and fMRI offers the temporal resolution of EEG as well as the high spatial resolution of fMRI and potentially allows for a more sophisticated assessment of the inter-regional direction of information flow . EffectiAnother point to consider when interpreting abnormal connectivity patterns is whether alterations in brain connectivity result from regionalised deficits that reverberate across networks , 135. AlThe studies of brain connectivity changes in schizophrenia and its modification by drug treatment might ultimately help the development of effective interventions. If one assumes that dysconnectivity underlies the expression of symptoms and can be pharmacologically targeted, drug-induced changes in functional brain connectivity might provide a useful imaging marker that might inform the development of new drugs. Considering the complexity and heterogeneity of schizophrenia, it would be somehow naïve to assume that a single pharmaceutical compound will be able to globally modify all aspects of pathogenetic dysconnectivity in schizophrenia . A more If not to identify potential targets for drug development, an increased effort in prospectively assessing the changes of connectivity with drug challenges or treatment would be as importantly helpful in distinguishing drug-induced from disease-induced changes in brain activity and connectivity. The vast majority of research into schizophrenia is conducted on already-treated, chronic patients and there is a need to identify drug confounds from abnormalities inherent to the disorder in order for treatment options and understanding to progress.


Bacteria spend most of their lifetime in non-growing states which allow them to survive extended periods of stress and starvation. When environments improve, they must quickly resume growth to maximize their share of limited nutrients. Cells with higher stress resistance often survive longer stress durations at the cost of needing more time to resume growth, a strong disadvantage in competitive environments. Here we analyze the basis of optimal strategies that microorganisms can use to cope with this tradeoff. We explicitly show that the prototypical inverse relation between stress resistance and growth rate can explain much of the different types of behavior observed in stressed microbial populations. Using analytical mathematical methods, we determine the environmental parameters that decide whether cells should remain vegetative upon stress exposure, downregulate their metabolism to an intermediate optimum level, or become dormant. We find that cell-cell variability, or intercellular noise, is consistently beneficial in the presence of extreme environmental fluctuations, and that it provides an efficient population-level mechanism for adaption in a deteriorating environment. Our results reveal key novel aspects of responsive phenotype switching and its role as an adaptive strategy in changing environments. To achieve this goal, unicellular populations need strategies that both enhance survival during stress and allow rapid resumption of growth as soon as the conditions improve. Controlling these strategies is important for the improvement of biotechnological processing and in the food industry, where microbial survival and regrowth is the main cause of food spoilage In their natural habitats unicellular organisms are frequently exposed to stress or starvation and only rarely encounter conditions that allow them to grow. In a competitive environment where growth and stress periods alternate, the species with the largest The question how a population can maximize its growth in a changing environment is a classic problem in microbiology. Cells can exist in different phenotypes, where each phenotype provides a growth advantage in a particular environment, but a disadvantage in other environments (compared to other phenotypes). Cells can increase long-term fitness by switching between the phenotypes. Previous works have studied the benefits of phenotypic diversity as well as of responsive and stochastic switching between phenotypes microbial life Adopting a stress resistant phenotype frequently involves growth arrest and the adoption of a metabolically downregulated state E.Coli, L. monocytogenes, M. vibrio and S. pombe, after depletion of glucose or nitrogen, exposure to heat stress, freezing, and acidic and salt stress for variable durations. In many species stress-induced and growth-induced pathways are antagonists, cf. Thus, when exposed to stress, cells face a tradeoff problem between longer survival and longer growth lags In the present article we focus on how cells tackle this tradeoff to select optimal strategies for coping with a changing environment. Can populations benefit from delaying a stress response? What determines whether dormancy is a good strategy or not? We consider both homogeneous and heterogeneous populations, taking into account the effects of continuous cell-cell variability, a hallmark of microbial populations under stress. Addressing these questions is important, e.g., for biotechnological processing and treatment of infectious diseases as mentioned above, yet experimental work that can answer them is still sparse To understand the implications of the stress-resistance vs. growth-lag tradeoff we propose a model based on the death rates and growth lags of stress resistant and vegetative (active) states. Upon stress exposure cells can enter a stress-protected state, characterized by a reduced death rate When stress ceases at time Here r” 1 cf. .The exact dependence of the growth lag on the death rate has not yet been quantified in detail. It is known, however, that the lag time increases with the stress resistance Hence, the growth lag has a minimum E.Coli, Vibrio S14, and Salmonella typhimurium mutants, and a lag phase To study the tradeoffs when adopting stress-protected states we first consider a single cycle of a stress and a regrowth phase of durations The population size ratio i) the stress duration ii) the growth period To understand which environments favor which strategy (maintaining ability to grow vs. maintaining viability) we calculate the population size ratio We thus predict that in environments which are characterized by frequent but short stress periods, a population that remains active and eventually delays its stress response can have significant growth benefits compared to populations which rapidly adopt a protected state upon stress exposure.As we have shown in the previous section, populations which remain in the vegetative state during stress can sometimes outgrow stress-resistant competitors. On the other hand it is clear that such populations will go extinct under sustained stress conditions, i.e., they will have a negative time-averaged growth rate How does the required downregulation level depend on the environmental conditions? By solving Eq. 3 with To achieve a positive net growth-rate populations must sufficiently downregulate such that the death rate during stress falls below a threshold. We showed that the degree to which stress resistance must be induced not only depends on the conditions of the stress environment but also on the durations of the growth periods.and resuming growth faster. As explained previously, the time-averaged growth rate depends on the death rate during stress and on the growth lag after stress. An interesting question to ask is whether there exist optimal induction levels of stress response systems and how these optimal induction levels depend on the characteristics of the microbial habitat. It can be seen already from In natural environments populations must not only survive but rather they must achieve a higher net growth rate than their competitors which means enhancing survival To answer this question we solve for the state In the regime of short stress durations and long growth times, the benefit of enhancing survival during stress is always smaller than the cost of a longer growth lag. Adopting a protected state upon stress exposure reduces the time-averaged growth rate, see In the regime of long stress and short growth periods no net growth is possible, as explained in the previous section, see also In the regime of intermediate stress and growth durations populations must reconcile survival with fast recovery. This is achieved at intermediate downregulation levels aA population is optimal not only in one environment advantage of intercellular noise by comparing the size of a homogeneous population For an average downregulation level Importantly, when Eq. 11 provides a reasonably good fit to a colony forming units (CFU) curve under stress, then the fitting parameters To understand the resumption of growth of a heterogeneous population we must know the distribution of downregulation levels and lag times by the time Hence, population heterogeneity of a stress protected state provides a substantial survival benefit at long stress durations. However, as shown in To understand under which conditions population heterogeneity provides a benefit during resumption of growth we must solve the population size equation, Eq. 2, for a distribution of lag times, or of downregulation levels respectively. For one cycle of stress and regrowth it reads:population growth-lag only. We therefore set It is helpful to first understand the effect of cell-cell variability on the Having considered the heterogeneous population-decline and heterogeneous population growth-lag separately so far, we now ask for the benefits of cell-cell variability in complete cycles of stress and growth During stress exposure the distribution of downregulation levels moves to ever decreasing values, due to the death of active and responsive cells. Resting state variability therefore provides a population-level mechanism that progressively sacrifices responsiveness while at the same time increasing stress resistance. This is particularly advantageous in the absence of an energy source, where an energy consuming regulatory mechanism to reliably sense and integrate environmental conditions over time and progressively downregulate individual cells, would represent an additional energetic burden.We have shown that cell-cell variability always provides a survival-advantage due to the presence of highly downregulated cells. Surprisingly, heterogeneous population recovery can also be slow compared to a homogeneous population if the growth rate after cellular recovery is too small (bulk driven recovery). In environments which are characterized by large fluctuations, intracellular noise appears as a simple strategy to increase the time averaged growth rate, whereas populations should suppress phenotypic variability in deterministically changing environments.In this article we have studied microbial stress responses as an induced phenotypic switch in stress and growth environments, including the case of cell-cell variability. We have proposed a model which parameterizes a metabolically downregulated state by a single parameter i) Delaying the induction of a stress-protected state, ii) adopting a state of intermediate downregulation, iii) adopting a dormant state, and iv) diversifying the population into cells of high and low stress resistance.We have shown that the inverse relationship between death rate and growth retardation explains and determines in which environmental regimes four commonly observed behaviors of stressed microbes provide a benefit: E.ColiE.Coli, where the iron stress response is induced only when stress durations exceed a temporal threshold. The delay is mediated by a small non-coding RNA, IsrRIsrR knock-out strains used in Time delays are a common motif in cellular decision making and frequently appear in microbial stress-responses In the other extreme, when growth durations are frequently shorter than a limit, a pessimistic strategy becomes optimal: leaving the protected state to resume growth when stress ceases can reduce the long term fitness. In this regime dormancy provides the highest fitness despite the absence of growth in short periods where growth is possible in principle and growth environments. A suitable model organism to verify this prediction are Mycobacteria with externally inducible mpr-AB promoters mpr-AB inducible strain mpr-AB inducer. We predict the existence of an optimal expression (induction) level of the stress response system. Overexpression of MprAB can increase the number of stress-surviving cells. These, however, will need too much time to degrade and dilute the growth repressors MprAB after stress and to resume the maximal growth rate. On the other hand, suboptimal expression will result in a large population fraction not surviving the stress phase.Frequently unicellular organisms do not fully shut down their metabolism when facing starvation or stress, but maintain a finite basal activity stochastic switching where fitness is maximized, when the switching rates mimic the environmental frequencies These findings have profound consequences for our current view on the role of responsive phenotype switching. When higher phenotypic fitness comes at longer transition times, i.e., when it involves morphological changes and considerable metabolic reorganization In heterogeneous populations with intercellular fluctuations of downregulation levels, highly responsive cells rapidly die when exposed to stress, whereas only downregulated subpopulations survive. This results in the prototypic non-exponential decay of colony forming unit (CFU) curves during stress exposure. We have derived an analytical expression which allows inference of cell-cell variability parameters from CFU curves, when the distribution of stress-resistance states in the population is continuous. This is particularly useful because it circumvents the extensive measurements needed to generate histograms and may therefore show great promise for better understanding population survival.In heterogeneous populations, differential cell death under stress leads to a gradually decreasing population-averaged activity. Thereby the population passively sacrifices responsiveness and increases stress resistance in a deteriorating environment. Such a passive adaptive mechanism which does not require active and energy consuming regulation provides an advantage in the absence of nutrient. An active mechanism which integrates stress conditions over time to progressively downregulate individual cells would represent an additional energetic burden and reduce population fitness.Previous works found that heterogeneity is advantageous, when individual cells cannot respond sufficiently fast to environmental changes Finally we would like to comment on the robustness of our results with respect to the specific details of the model. As yet the exact inverse dependence of the lag-time on the death-rate has not been measured in detail. In this article we have adopted a first order approximation where Recently many of the molecular players involved in microbial stress responses and cellular downregulation have been identified and the single cell regulatory kinetics have been characterized


Cervus elaphus) and this ungulate exhibits significant sexual size dimorphism, life history traits and segregation, we hypothesized that tick parasitism on males and hinds would be differentially influenced by each of these factors. To test the hypothesis, ticks from 306 red deer—182 males and 124 females—were collected during 7 years in a red deer population in south-central Spain. By using generalized linear models, with a negative binomial error distribution and a logarithmic link function, we modeled tick abundance on deer with 20 potential predictors. Three models were developed: one for red deer males, another for hinds, and one combining data for males and females and including “sex” as factor. Our rationale was that if tick burdens on males and hinds relate to the explanatory factors in a differential way, it is not possible to precisely and accurately predict the tick burden on one sex using the model fitted on the other sex, or with the model that combines data from both sexes. Our results showed that deer males were the primary target for ticks, the weight of each factor differed between sexes, and each sex specific model was not able to accurately predict burdens on the animals of the other sex. That is, results support for sex-biased differences. The higher weight of host individual and population factors in the model for males show that intrinsic deer factors more strongly explain tick burden than environmental host-seeking tick abundance. In contrast, environmental variables predominated in the models explaining tick burdens in hinds.The interactions between host individual, host population, and environmental factors modulate parasite abundance in a given host population. Since adult exophilic ticks are highly aggregated in red deer ( Tick distribution in their hosts is frequently found to be highly aggregated in a few individuals within the host population, which determines that a few hosts are responsible for feeding large amounts of ticks  males display a “live hard, die young” strategy  found no sex-related effect on tick burdens  and Eurasian wild boar (Sus scrofa) but also small numbers of mouflon (Ovis aries musimon) and aoudad (Ammotragus lervia). Orography in the estate is formed by hill chains (up to 100 m high) bordering three main valleys. Hills are covered by Mediterranean shrub ecosystem composed by scattered Quercus ilex trees and shrub dominated by Cystus spp. Pistacia spp., Rosmarinus spp., Erica spp., Arbutus unedo, and Phyllirea spp. Valleys are dedicated to grow seasonal cereal crops for game feeding. Climate is continental Mediterranean with cold winters and very hot and dry summers and rainfall—ranging 300–700 mm annually—is highly seasonal. Supplementary food  is available ad-libitum along the year for deer on selective feeders located at the bottom of valleys (8 feeding points). Additionally, water supply is maintained all-over the year in eight water ponds distributed along riverbeds in valleys.The study area comprised a 900 ha hunting estate located in Ciudad Real province  of which 700 ha are dedicated to game rearing for hunting purposes, mostly Iberian red deer  was collected while a representative subsample of ticks were collected in highly parasitized individuals (>30 ticks). Every immature stage located was collected from deer carcasses. Collected ticks were identified to species level Manilla, .Every deer surveyed was subjected to a detailed necropsy to detect any lesion caused by macro or microparasites  located in the study hunting estate  greatly condition tick phenology, activity, and survival /n]1/2  and expressed in percentage.For descriptive analyses of parasitization rates the statistical uncertainty was assessed by calculating the 95% confidence interval for each of the proportions according to the expression 95%C.I. = 1.96[Using an inductive approach we quantified the effect of the main factors able to explain tick burdens on red deer, at individual level. Predictors were considered in generalized linear models with a negative binomial distribution and a logarithmic link function , or with the model that combines data for males and hinds. However, if parasite loads on males and hinds similarly responded to the explanatory factors, then any of the independent models could precisely determine the rates of either sex, and in this occasion better adjust terms and more accurate predictions could be attained with the model carried out by combining data from males and hinds than with the independent model for each sex. Two analytical procedures were used in order to compare the model in the previous terms: variation partitioning and cross-validation.Variation partitioning procedures , Rh. bursa , Rh. sanguineus , and Dermacentor marginatus  and nymphs belonged to Hy. lusitanicum  and Rh. bursa . Annual average adult tick abundance per deer experienced a decrease along study years , Alzaga et al. , and consequently both influence tick burden in a positive proportional direction. Body size was selected as the most appropriate measure of animal's body surface exposed to questing ticks because body mass could be modulated by ad-libitum availability of supplementary food. Similar results relating KFI and parasitism in males were obtained for red deer parasitized by Elaphostrongylus cervi in south-central Spain  DRB-2 haplotype 2 displayed significantly higher probability of being lowly parasitized by ticks with respect individuals displaying the other three most abundant MHC-II-DRB-2 haplotypes in the estate. Data from a second study was re-analyzed for this study and showed that haplotype 2 was more frequent in hinds than in males (Fernández-de-Mera et al., Another individual trait that could rely behind male-biased tick parasitism is innate genetic resistance. Fernández-de-Mera et al. —in the sDensity of hosts was selected in the independent models for each sex as related to tick burden, probably due to the fact that host densities regulate the percentage of adult ticks in the population that find a host and reproduce, thus contributing to densities of host-seeking ticks (Ruiz-Fons et al., Hyalomma spp. ticks (Ruiz-Fons et al., Wild boar are efficient hosts for Hy. lusitanicum in the study estate which peaks in late spring and early autumn when mean temperatures are high.Environmental factor captured most of the variation explained in tick burdens in individual models, especially in hinds Table . ClimateThe higher weight of host individual and host population factors in the model for males show that intrinsic deer factors are more efficient predictors of tick burden than environmental host-seeking tick abundance, at least when food availability is not a constraint. According to these results, controlling ticks in males such as acaricide spread on males through selective feeders or application of anti-tick vaccines to males only, would hypothetically result in a reduction of tick burdens in hinds since host-seeking tick abundance would be reduced significantly. Whether such an specific tick control measure on males would result in an immediate increase of tick burdens on hinds or in a substantial reduction should be specifically tested in the future.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.


Developmental programing is gaining considerable leverage as a conceptual framework for understanding individual variability in human behavioral and somatic health. The current mini-review examines some of the key conceptual and methodological challenges for developmental programing research focused on fetal sex steroid exposure and physical, behavioral, physiological, and health outcomes. Specifically, we consider the bases for focusing on sex steroids, methods for assessing prenatal steroid hormone exposure, confounding factors, and the most relevant postnatal outcomes. We conclude with a brief consideration, based on current knowledge, of the applications of the existing findings for further research and practice. The developmental origins of health and disease hypothesis and the programing mechanisms that underlie it are a major focus of current basic science and clinical health research. A common theme is that stress  experienced by the mother is transmitted to the fetus and the ensuing developmental changes may have long-lasting effects on offspring biology and behavior. The hypothalamic–pituitary–adrenal (HPA) axis – and particularly glucocorticoid exposure – has attracted attention as a likely mediating mechanism –3. HowevIt is natural that HPA axis-mediated programing mechanisms have attracted substantial research attention given the dominant role of prenatal stress as a “risk phenotype” in the animal and, more recently, human research. The mediating role of glucocorticoids in programing fetal physiology may extend beyond prenatal psychosocial stress to also include exposure to other types of stressors, such as nutritional deprivation. Moreover, there are equally compelling reasons why an exclusive focus on a glucocorticoid-mediated mechanism will be inadequate and consideration of complementary mechanisms, notably sex steroid hormones, could be informative. For example, the HPA and hypothalamic–pituitary–gonadal (HPG) axes show considerable overlap and interaction ; just asOne way of evaluating the likely importance of sex steroids in developmental programing is to examine sex differences in the associations between prenatal stress and outcomes in offspring. For instance, in animal models, male and female offsprings often show different patterns of developmental programing . In someWhether or not there are sex differences in human studies of the effects of prenatal stress/anxiety on child outcomes is far from clear. Some examples have been reported for behavioral and cognitive development , 9 and tTwo lines of study provide evidence of sex steroid involvement in stress-related developmental programing. In animal models, prenatal stress is associated with changes in anogenital distance (AGD), a marker of prenatal androgen exposure; these associations have now been noted in humans –15. CritThere are several methodological challenges for future research on the possible programing role of prenatal sex steroid exposure; we consider several in this mini-review.The first, most basic question is how to assess fetal exposure to sex steroid hormones. Several studies have inferred fetal exposure to sex steroids from prenatal maternal distress , 23, altin utero is an essential but difficult task for research. The availability of non-intrusive and reliable estimates of fetal exposure has proved difficult and is a central challenge to overcome in future research.Indexing fetal exposure to sex steroids Distinguishing the impact of sex steroid hormones from other sources of programing is another major challenge for research. For example, cortisol and testosterone are positively correlated in fetal blood  and in aOn the other hand, it is unclear if the findings can be generalized to non-clinical populations with fetal hormonal exposures within the normal range of variation. Other means of differentiating between glucocorticoid and sex steroid-based programing within healthy populations are needed. It is an interesting possibility that the developmental programing studies associated with maternal prenatal distress may have over-attributed effects to stress hormones because they have (largely) ignored sex steroids.A novel and potentially promising approach to indexing fetal steroid hormone exposure is to examine placental gene expression and epigenetic changes. As the main maternal–fetal interface, the placenta is of inarguable importance for understanding developmental programing. To date, research has been influenced by a glucocorticoid-mediated model. For instance, there has been great interest in the effects of stress on placental production of 11-β-hydroxysteroid dehydrogenase 2 (11BHSD2), an enzyme which shields the fetus from maternal cortisol by converting it to inactive cortisone . HoweverThere are obviously substantial hurdles to assessing placental gene expression; it is a methodology that poses significant collection, cost, and laboratory demands. In healthy pregnancies, moreover, we are limited to looking at placental morphology and physiology at birth rather than at critical periods earlier in gestation. Nevertheless, examining placental variation, particularly in steroidogenesis pathway activity, in relation to prenatal exposures and postnatal outcomes requires attention given the (other) inherent challenges of estimating fetal exposure to sex steroids in a non-intrusive, reliable way.A final challenge to be considered is the selection of relevant postnatal phenotypes. Traits with notable sex differences may be the most fruitful starting points. Autism spectrum disorders and associated traits, for instance, differ quite notably in prevalence and presentation between the sexes . Play bein utero sex steroid programing. Studies showing sex differences in infancy are interesting because there are minimally detectable levels of sex hormones in circulation; that means that these infant sex differences may be induced by prenatal sex steroid exposure. There are other well-known differences between the sexes that are evident early in development, including physical growth and brain development, e.g., Ref. (Levels of circulating sex hormones are extremely low from shortly after birth until puberty. Nevertheless, even in infancy there appears to be sex differences in neurodevelopmental traits , suggestg., Ref. . A challResearch on human health and development is just beginning to translate the animal work on developmental programing effects of sex steroids. Further studies are needed to substantiate this emerging line of investigation and to provide a broader biological context in which to interpret the sizable research based on developmental programing associated with prenatal stress and HPA axis mechanisms, a literature which has begun to influence practice and policy, e.g., Ref. . ProgresThe 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.


Explaining the contribution of host and pathogen factors in driving infection dynamics is a major ambition in parasitology. There is increasing recognition that analyses based on single summary measures of an infection  do not adequately capture infection dynamics and so, the appropriate use of statistical techniques to analyse dynamics is necessary to understand infections and, ultimately, control parasites. However, the complexities of within-host environments mean that tracking and analysing pathogen dynamics within infections and among hosts poses considerable statistical challenges. Simple statistical models make assumptions that will rarely be satisfied in data collected on host and parasite parameters. In particular, model residuals (unexplained variance in the data) should not be correlated in time or space. Here we demonstrate how failure to account for such correlations can result in incorrect biological inference from statistical analysis. We then show how mixed effects models can be used as a powerful tool to analyse such repeated measures data in the hope that this will encourage better statistical practices in parasitology. Parasitologists aim to understand the factors that determine the outcome of infections , and how these factors change in response to a new intervention or other environmental variables. However, infections are complex and dynamic: multiple interacting factors shape parasite traits, and within-host environments vary over time and between different niches Recent years have seen the increasing use of statistical tools, such as mixed effects models, which allow researchers to analyse pathogen dynamics within infections while controlling for issues of pseudo-replication arising from repeated measurements on the same host  contain potential sources of non-independence, which are not present when individuals are only measured once. In particular for time-series data, unmeasured factors can produce correlations in the data  over days, weeks, or months . These correlations can be strong and, importantly, may lead to the appearance of spurious patterns in the data  and 2. FThere are straightforward solutions to the problems caused by temporal auto-correlation that are routinely used in other biological disciplines, but remain rarely implemented in parasitology. While previous reviews have highlighted the need to track infection dynamics e.g.,  and encop-value for which a significant difference is accepted There are various ways in which violations of the auto-correlation assumption can be dealt with. One approach is to make tests more conservative by reducing the When analysing time course data, researchers should apply the following approach: 1) fit grouping variables as a random effect if required, 2) add temporal auto-correlation structure to the model at the appropriate level within the random effects structure, 3) compare the above models to test whether the auto-correlation structure improves the fit, 4) retain the auto-correlation structure if the fit is improved and exclude it if not, 5) ensure the inclusion or exclusion of an auto-correlation structure is reported in the analysis methods or results section of manuscripts.http://www.R-project.org) a linear mixed effects model asking whether parasite density varies during infections sampled daily in different experimental treatments in mice would be coded as:For example, in the R statistical software package (The R Foundation for Statistical Computing; Advances in statistical methodology should provide important and useful tools for understanding infections and disease in just the same way as do advances in genetic, molecular, and immunological methods. Investing in learning how to effectively use tools, such as mixed effects models, pays by providing robust and novel insight into the roles of hosts and parasites in shaping patterns of disease. However, as with other methodological advances, the improvements to biological understanding they provide depend crucially on them being applied and interpreted correctly. Temporal correlation in time-course data can compromise statistical analyses by increasing the likelihood of false positives, yet this problem has been largely overlooked in parasitology. We strongly support the implementation of more sophisticated statistical analyses in which the assumptions underlying models are fulfilled to safeguard against inaccurate or misleading results and provide a solid foundation from which to progress understanding of disease.


Pancreatic cancer is a devastating disease with an unacceptably high mortality to incidence ratio. Traditional therapeutic approaches such as surgery in combination with chemo- or radiotherapy have had limited efficacy in improving the outcome of this disease. Up until just under a decade ago, the prominent desmoplastic reaction which is a characteristic of the majority of pancreatic ductal adenocarcinomas (PDAC) had been largely ignored. However, since the identification of the pancreatic stellate cell (PSC) as the key cell responsible for the production of the collagenous stroma in PDAC, increasing attention has been paid to the role of the stromal reaction in pancreatic cancer pathobiology. There is now compelling evidence that PSCs interact not only with cancer cells themselves, but with several other cell types in the stroma  to promote cancer progression. This review summarizes current knowledge in the field about the influence of PSCs and the stromal microenvironment on cancer behavior and discusses novel therapeutic approaches which reflect an increasing awareness amongst clinicians and researchers that targeting cancer cells alone is no longer sufficient to improve patient outcome and that combinatorial treatments targeting the stroma as well as the cancer cells will be required to change the clinical course of this disease. Pancreatic cancer  is a lethal disease. It is the fourth leading cause of cancer related death in developed countries , all of which have the potential to influence local growth and distant spread of pancreatic tumors.PSCs were first described by Watari et al. . These rin vitro and in vivo. Since 1998, PSCs have been extensively characterized and their roles in fibrogenesis and tumor stromal interactions have been delineated in some detail , proliferate, migrate, and produce excessive amounts of ECM proteins, resulting in a loss of the balance between ECM production and degradation and leading eventually to fibrosis. During an acute episode of pancreatic injury, PSCs are activated early, and secrete excess ECM proteins that lay down a lattice for regenerating epithelial cells. As the injury resolves, activated PSCs are lost most likely through apoptosis , vimentin, and nestin (intermediate filament proteins) as well as the neuroectodermal markers such as nerve growth factor (NGF) and neural cell adhesion molecule; the expression of these selective markers differentiates PSCs from fibroblasts Figure . At the Role in pancreatic exocrine secretion: The secretagogue cholecystokinin (CCK) has been shown to directly stimulate exocrine secretion from rodent pancreatic acinar cells by binding to CCK receptors on the cell surface. However, there has been some controversy in the published literature regarding the direct effects of CCK on human pancreatic acinar cells, with Ji et al. reporting in 2001 and 2002  and support a role for PSCs in pancreatic cancer progression.In recent years, several studies have reported orthotopic models of pancreatic cancer involving direct implantation/injection into the mouse pancreas of human pancreatic cancer cells  with or without human PSCs (hPSCs)  compared to tumors produced by the injection of cancer cells only, suggesting that PSCs stimulate angiogenesis in pancreatic cancer  but also within metastatic nodules in the mediastinum, liver, and diaphragm. These observations indicate that PSCs can travel to distant metastatic sites (possibly with cancer cells), where they may be reasonably postulated to play a role in the seeding, survival, and proliferation of cancer cells. A subsequent study reported similar findings in a model of lung cancer , KPGC mice , and TGFβ type II receptor organ specific knockout in the mouse pancreas . The lesions in these models progress from preinvasive ductal changes (PanIN lesions) to overt carcinoma and metastases, with an associated progressive increase in the surrounding stromal reaction. Importantly, activated PSCs have been observed in the earliest PanIN lesions  models exhibit the development of spontaneous pancreatic cancer with a prominent endogenously produced stromal reaction , they are activated and manifest increased proliferation, migration, and ECM production , has been reported to induce significantly greater effects on cancer cell proliferation and invasion than CD10One of the major factors responsible for the poor prognosis of pancreatic cancer is its propensity for recurrence, with recurrent tumors postulated to arise from a niche of drug resistant cancer stem cells. Recent evidence suggests that PSCs may play a role in facilitating such a stem cell niche in pancreatic cancer. Hamada et al.  have repAs the interactions between cancer cells and PSCs have become increasingly recognized, factors mediating these interactions have also attracted much interest. The increased proliferation of PSCs induced by cancer cells is likely mediated by platelet-derived growth factor , which stimulates mitogen-activated protein kinase signaling (MAPK) in PSCs  are strongly supported by in vitro studies. PSCs have been shown to stimulate tube formation (a measure of angiogenesis) of human microvascular endothelial cells, an effect mediated by vascular endothelial growth factor (VEGF) secreted by PSCs  implies that PSCs can migrate through an endothelial layer. Using a Boyden chamber method with a porous membrane coated by a monolayer of endothelial cells, Xu et al.  have shoin vivo evidence to suggest that PSCs may play a role in this immune evasion by sequestering CD8+ T cells and reducing their infiltration around tumor cells, thus preventing the T cells from exerting their anti-tumor effects. In vitro support for this concept comes from studies showing that PSCs exert a chemotactic effect on CD8+ T cells, and that this effect is mediated by the PSC-derived chemokine CXCL12  has been observed in intraductal papillary mucinous neoplasms of the human pancreas , fibronectin synthesis, and MMP expression  or with targeted drugs such as growth factor inhibitors or with soluble taxanes such as Abraxane. The most recent studies combining gemcitabine with Abraxane (nab-Paclitaxel)   was developed to overcome the issues of solubility and to enhance drug delivery through albumin facilitated receptor-mediated transcytosis Yardley, . AdminisWith regard to targeting the immune cells in PDAC stroma, Beatty et al.  have demAngiotensin II receptor antagonists: Angiotensin II, a component of the renin-angiotensin system, has been shown to induce PSC proliferation, ECM synthesis and migration, and to increase the production of growth factors by PSCs. Thus, angiotensin II receptor blockade, already in clinical use in hypertension, has been recently assessed in a subcutaneous xenograft model of pancreatic cancer. Using the inhibitor olmasartan, Masamune et al.  report aIn vitro studies showed that pirfenidone inhibited PSC proliferation, invasion, and migration, and interrupted the interaction between pancreatic cancer cells and PSCs; these effects were associated with decreased expression of PDGF-A, HGF, periostin, collagen type I, and fibronectin in PSCs, as well as reduced PSC activation (decreased α-SMA expression) : Treatment with this compound using subcutaneous and orthotopic models of pancreatic cancer has been reported to decrease the growth of tumors produced by the injection of a mixture of pancreatic cancer cells and PSCs, but not that of tumors produced by cancer cells alone : This compound enzymatically degrades one of the predominant components of the ECM, hyaluronan. PEGPH20 treatment of KPC mice resulted in stromal depletion and decompression of tumor vessels leading to an increase in tumor vascular patency without increasing vessel density. PEGPH20 also increased fenestrations in endothelia and interendothelial junction gaps that increased the permeability of the endothelium to macromolecules. When combined with gemcitabine, PEGPH20 treatment improved the delivery of gemcitabine to tumor cells inhibiting tumor growth and extending the median survival of the mice  warrant attention as potentially useful, additional therapeutic targets in this disease. The challenge in this field of research will be to ensure that preclinical testing is carried out with experimental models (or a range of models) that not only closely simulate the pathology, but also account for the heterogeneity of human pancreatic cancer, so as to successfully translate research findings into clinically effective therapies.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.


No reliable anatomical or functional alterations have been confirmed in psychiatric neuroimaging; however it can become reliable with translational impact on clinical practice when considering crucial methodological issues. We provide guidelines to authors, editors and reviewers in the implementation/evaluation of neuroimaging studies to bend neuroimaging to be more than basic neuroscience. More than three decades after Johnstone’s first computerised axial tomography of the brain of individuals with schizophrenia , no consA number of methodological problems may underlie the inconsistencies across studies and the difficulty of identifying reliable results. Heterogeneity in psychiatric neuroimaging originates from multiple differences across studies: in conceptual issues underlying psychiatric diagnoses and psychopathology ,3, the i“the excess significance may be due to unpublished negative results, or it may be due to negative results having been turned into positive results through selective exploratory analyses”[localization of the potential brain abnormalities, which should be based on a whole-brain analysis of the differences between patients and controls. To make an analogy, it’s as if an attorney decides to investigate only an arbitrary subgroup of the suspects of a crime, and not to report any proof, which may involve individuals which he wants to keep untarnished.The latter point is critically addressed by the recent study of Ioannidis . He statanalyses”. Becauseanalyses”. Additioanalyses”. These pAs Ioannidis acknowledged these concerns do mainly refer to morphometry studies and not directly extend to automated whole-brain voxel-based studies or functional imaging studies. In particular, voxel-based meta-analyses have the potential to overcome the limited sample size of individual studies revealing structural differences at specific brain coordinates rather than differences in volumes of pre-specified ROIs. A recently developed meta-analytic method, Signed Differential Mapping ,8, consiOnly by overcoming these biases, the results of psychiatric neuroimaging can become more reliable and have a translational impact on clinical practice. The study by Ioannidis represents a milestone in psychiatric imaging, pointing to crucial methodological issues at the level of imaging analysis. Although the Ioannidis study makes general recommendations, this manuscript tries to formulate a checklist of practical guidelines for authors, editors and reviewers that are easy to implement and follow. This may help to ultimately bend psychiatric neuroimaging to be something more than basic neuroscience:i. With an increasing number of ways of preprocessing the data becoming available, this should be described in enough detail by the authors to allow exact replication;ii. ROI studies  should first report standard whole brain results and acknowledge if no significant clusters were detected at whole brain level before presenting the ROI findings;iii. Both ROIs and whole brain studies should first report the results significant at p < 0.05 corrected for multiple comparisons  and then employ more liberal thresholds;iv. When several ROIs are used, correction for multiple comparisons should be based on a mask which includes all of them rather than considering each ROI separately;v. Authors should be encouraged to blind the statistical analyses of the imaging datasets to avoid ROI analyses be built post-hoc on the basis of the results;vi. All studies should report a statistical analysis modelling an agreed set of possible confounding variables; these could include, for instance, gender, age and handedness. In addition, studies would have the option of reporting further statistical analyses modelling additional study-specific confounding variables;vii. All studies should acknowledge the number of analyses or brain correlations performed, giving a clear rationale for each, to avoid conducting exploratory analyses and reporting the most significant result;viii. The potential overlapping of the patient and control group with previously published studies should be clearly acknowledged, and the spatial coordinates always reported, to assist future voxel-based meta-analyses in the field;ix. Peer-reviews should be as strict when assessing the methods of a study reporting abnormalities in expected brain regions, as when assessing the methods of a study not finding any expectable finding;x. Acceptance or rejection of a manuscript should not depend on whether abnormalities are detected or not, nor on the specific brain regions found to be abnormal.The authors’ declare that they have no competing interests.SB and PFP conceived these guidelines and drafted the manuscript. JR and AM helped discussing the limitations of imaging analysis. All authors read and approved the final manuscript.


Neurotrophic factors are best known for their roles in both development and continued maintenance of the nervous system. Their strong potential to elicit pro-survival and pro-functional responses in neurons of the peripheral and central nervous system make them good drug candidates for treatment of a multitude of neurodegenerative disorders. However, significant obstacles remain and need to be overcome before translating the potential of neurotrophins into the therapeutic arena. This article addresses current efforts and advances in resolving these challenges and provides an overview of roadmaps for future translational research and neurotrophin-based drug developments. NTR). The spatial and temporal balance achieved between neuronal survival and death depends on the overall level of neurotrophin present and the type of receptors that are expressed [Neurotrophic factors or neurotrophins are a group of growth factors which have been classically described for their ability to regulate differentiation and to support growth during development of the vertebrate nervous system. The family of neurotrophins consists of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT3), and neurotrophin 4 (NT4). In order to elicit a survival response, each binds to one member of the tyrosine receptor kinase (Trk) family: NGF binds to TrkA, BDNF and NT4 bind to TrkB, and NT3 binds to TrkC. Each of the neurotrophins can similarly respond through an apoptotic pathway initiated by binding to the 75 kD neurotrophin receptor  pathway, the phosphatidylinositol 3-kinases (PI3K)/ the protein kinase B  pathway, and the phospholipase C-γ pathway Figure . BindingGiven the critical role played by neurotrophins in regulating neuronal functions, it is not surprising then that a significant number of psychiatric and neurodegenerative disorders is associated with altered NGF and BDNF levels and with changed expression of their receptors. For example, neurodegenerative phenotypes similar to Alzheimer’s disease (AD) are observed in a mouse model in which half of the NGF level is neutralized by antibodies . In factThe key role for NGF was discovered in early studies on transected fimbria in which administering NGF upon transection was able to markedly reduce cholinergic neuron death, which was typically induced by the procedure . In addiWhile it is still unclear as to why certain areas of the brain are more vulnerable in various disorders over other areas of the brain, one effect that is certain is that the synaptic loss and neuronal dysfunction in these areas lead to detrimental changes to overall synaptic transmission -27. IndeThe well documented role for neurotrophic factors to prevent cell death and to maintain cellular function has led scientists to investigate their translational benefit(s). To date, the potential beneficial effect of neurotrophins, NGF and BDNF, in particular, have been explored in light of several neurodegenerative disorders, including but not limited to AD, Amyotrophic lateral sclerosis (ALS) , HuntingAlthough there are strong rationales suggesting that increasing supply of neurotrophins to degenerating neurons may be a potent way to restore neuronal function in neurodegenerative conditions, delivering neurotrophins into the brain has proven to be a non-trivial matter. Notoriously, CNS diseases are difficult to treat due to the presence of the blood brain barrier (BBB) that makes it almost impossible for large proteins and complex compounds to cross from the blood into the brain. In addition, the cortical and subcortical circuits of the brain are interconnected resulting in crosstalk among multiple regions, so coming up with a treatment strategy that selectively targets affected neurons only, but not those unaffected ones, is a great challenge that has to be carefully considered. To further compound these issues, neurotrophins are relatively large, polar molecules that cannot readily cross BBB and therefore must be administered directly into the central nervous system (CNS). Indeed, all current delivery strategies involve invasive procedures as discussed below.To bypass the inability of neurotrophins to cross BBB, purified neurotrophins can be directly infused to the brain by intracerebroventricular (ICV) injection. This delivery route is particularly suitable for NGF to treat BFCN degeneration, since BFCNs extend their axons throughout the hippocampus and neocortex. NGF that is infused into the lateral ventricle can act on the TrkA receptor located at the axonal termini to retrogradely transmit trophic support signal for BFCNs. This approach has been proven especially effective in preventing loss of BFCNs in rodents associated with lesions and aging as mentioned above. However, clinical trial with NGF infusion showed that, although long-term NGF administration by ICV injection may cause certain potentially beneficial effects, the intraventricular route of administration is also associated with significant side effects , such asNGF involvement in pain is stemmed from its ability to activate the nociceptive response in sensory neurons . NGF as in vivo data from this dual approach is still lacking [Current efforts with infusion of other neurotrophins have yielded similarly disappointing results. For example, to increase the delivery of BDNF, one study has used intrathecal infusion of N-terminal pegylated BDNF after spinal cord injury. While the authors were able to show that pegylated BDNF was able to reach the spinal cord and induce expression in that area, they saw no improved axonal response or locomotor recovery, suggesting the amount of BDNF that was delivered was still insufficient . In a se lacking . Intrapu lacking . More im lacking . This re lacking ,45.To circumvent the lack of significant therapeutic benefits in combination with serious adverse effects associated with the infusion approach, other methods are designed to achieve more targeted delivery of neurotrophins directly to those populations of neurons affected in disease. This would allow for more controlled and increased dosing while potentially eliminating side effects through avoiding unknown interactions of the neurotrophin. Currently, two approaches of direct delivery of neurotrophic factor into subcortical sites of the brain have been developed and practiced: transfer of cells modified to express neurotrophic factor and delivery of an engineered viral vector encoding the neurotrophic factor protein. The first technique involves establishing cell lines, preferably from the donor host, to express the neurotrophic factor through transfection and selection using vectors containing the gene of interest. Once expression of the gene is assessed and optimized, the cells can be transferred into brain regions to function locally in providing neurotrophic factor Figure . Early pAt the beginning of 2001, eight subjects both male and female in early stage AD were enrolled. Primary autologous fibroblasts derived from each subject were genetically modified to produce human NGF using retroviral vectors. Once NGF production was established the cells were injected into the basal forebrain of the subjects either unilaterally or bilaterally. Of those that safely received the NGF delivery, the mean Mini-Mental Status Examination (MMSE) scores showed a mean rate-of-decline reduction of 51 % over a period of 22 months, and an even higher reduction during the 6–18 months when NGF production remained robust. In addition, there were cognitive improvements and increased PET scan activity in several areas of the brain. Post-mortem analysis of one subject which died 5 weeks after NGF delivery confirmed that there was robust NGF expression in the cell grafts and that cholinergic axons showed sprouting. Overall this study provided the first clinical evidence that directed neurotrophic factor delivery could provide therapeutic benefit without side effects commonly associated with neurotrophic factor infusion. Only hemorrhages in two subjects were observed during injection that may be due to unwanted movements during the procedure. One patient did not recover and died shortly after surgery. General anesthesia has been since adopted to mitigate the problem . CurrentThis technique has also been applied successfully for grafting of BDNF and NT-3 in the treatment of spinal cord injuries. Although not yet performed in human patients, fibroblasts that were modified to express BDNF or GDNF and NT-3 and were grafted into sites of spinal cord injury induced sustained regenerative and sprouting responses into the sites of injury in rats ,56. Overin vivo studies that have been performed thus far [Due to advances in molecular research in the past decade, viral vector-mediated gene delivery may prove to be a more optimal approach Figure . Deliverthus far . Similarthus far . AAV-medthus far . Studiesthus far ,62. Howethus far , indicatViral treatment has also been explored for treating other disorders such as the lysosomal storage disease, late infantile neuronal ceroid lipofuscinosis  in whichIt is worth mentioning that many of the challenges facing either direct infusion of neurotrophic factor or cell-, viral vector-mediated gene delivery methods may be overcome with small molecules that target the receptor for the neurotrophic factor instead of introducing the neurotrophic factor itself. This would allow for specific activation of only one type of receptor, such as TrkA or TrkB and not p75, or vice versa, potentially alleviating the side effects. To this end, the discovery and use of peptide mimetics, short peptides that have improved bioavailability and lower degree of proteolysis , and smaNeurodegenerative disorders are very complex diseases. Although neurotrophic factor-based strategies have offered great potential, the biggest unknown is whether such approach by itself is adequate in halting and reversing the course of progression of these diseases.As years have passed and many clinical trials later, the idea that “a single magic bullet approach” or one drug can act as the sole solution for treating neurodegenerative disorders has proven not very successful. This is highlighted well in the case of Alzheimer’s disease. For example, acetyl cholinesterase inhibitors (Aricept) and N-methyl-D-Aspartate (NMDA) receptor antagonists (Mementine) have been approved for the treatment of AD, but both treat symptoms and show only moderate efficacy. Unfortunately, both fail to slow the rate of cognitive decline in AD patients . FurtherGoing forward, the idea of combinational therapies for treating various neurodegenerative disorders is worth serious consideration, given the fact that so many attempts with monotherapies have not yielded any success. For many non-neurodegenerative disorders co-therapies targeting multiple disease pathways and symptoms are actively being used and evaluated. For rheumatoid arthritis, disease modifying antirhematic drugs (DMARDS) are used in combination with fast acting glucocorticoids to alleviate the symptoms of inflammation quickly . The comNGF and its other family members provide potent trophic support to neurons. Their robust effects in rescuing degenerating neurons cannot be matched in this regard by any small molecules or compounds identified thus far. Neurotrophin-based therapies may well prove to be an effective means to combat epidemic neurodegenerative diseases. Yet, many daunting challenges remain to be resolved. Furthermore, it remains to be seen if such strategies that aim at a single target will be sufficient to cure these diseases. In the end, the inherent complexity of neurodegenerative diseases may require combinational therapies that target multiple pathways for effective treatment.The authors declare that they have no competing interests.AW drafted the manuscript, CW critically revised the manuscript. Both authors read and approved the final manuscript.


More than 50% of women with migraine report an association with menstruation. Attacks are most likely to occur during the two days before menstruation and the first three days of bleeding and are typically without aura, even in women who have attacks with aura at other times of the cycle. The majority of menstrual attacks can be controlled with symptomatic treatment alone. If this is inadequate, pre-emptive treatment with perimenstrual estradiol, triptans or non-steroidal anti-inflammatory drugs (NSAIDs) may be effective.Suppression of the menstrual cycle with anovulatory contraceptive agents is an additional option for management, particularly for women who also require contraception. Using combined hormonal contraception continuously, without a break, can prevent estrogen “withdrawal” migraine during the hormone-free interval.Limited research suggests that high levels of estrogen, such as occur with use of combined hormonal contraceptives (CHCs), can trigger migraine with aura. Since aura and CHCs are independent risk factors for ischaemic stroke, the appropriateness of CHCs solely for contraception in women who have migraine with aura needs careful consideration.During pregnancy, migraine follows a benign course with improvement in migraine without aura likely by the second trimester. However, the high oestrogen state is associated with increased migraine aura in susceptible women. In these women, hypertensive disorders of pregnancy and stroke are more likely to occur although the absolute risk remains small. Women benefit from early advice on drugs that can be continued during pregnancy in order to optimize control and avoid unnecessary concern


The majority of adolescents report to have smoked a cigarette at least once. Adolescence is a critical period of brain development during which maturation of areas involved in cognitive functioning, such as the medial prefrontal cortex (mPFC), is still ongoing. Tobacco smoking during this age may compromise the normal course of prefrontal development and lead to cognitive impairments in later life. In addition, adolescent smokers suffer from attention deficits, which progress with the years of smoking. Recent studies in rodents reveal the molecular changes induced by adolescent nicotine exposure that alter the functioning of synapses in the PFC and underlie the lasting effects on cognitive function. In particular, the expression and function of metabotropic glutamate receptors (mGluRs) are changed and this has an impact on short- and long-term plasticity of glutamatergic synapses in the PFC and ultimately on the attention performance. Here, we review and discuss these recent findings. Adolescence is an important developmental period when a child has to make a transition to an independent status of adult. Such transition demands an ability to take risks and a taste for novelty but also emergence of self-control and more adult decision-making strategies. Also, brain development is not complete by adolescence, especially maturation of areas involved in cognitive functioning, such as the medial prefrontal cortex (mPFC), is still ongoing. Brain development continues throughout adolescence, though the speed and timing of maturation varies for different brain areas , which take part in cholinergic signalling. Twelve genes have been identified encoding neuronal nicotinic receptors , is based on Hebb's postulate often summarized as “r” Hebb, . It atter” Hebb, . In PFC,r” Hebb, . We showr” Hebb, . In PFC r” Hebb, . Nicotinr” Hebb, . In layer” Hebb, . Thus, n3H-epibatidine labeled high-affinity nicotinic receptors in the mPFC, but not in occipital cortex. Adolescent, but not adult nicotine exposure increases 3H-Epi-binding of mPFC receptors on the first day of abstinence following 10 days of nicotine injections. This is paralleled by an mPFC-specific increase in expression of nAChRs containing α4 and β2 (but not α5) subunits or high-affinity nAChRs. The increased expression of high-affinity nAChRs in adolescents is accompanied by an increase in nicotine-stimulated GABAergic synaptic transmission in the mPFC  are significantly upregulated during adolescent nicotine exposure Figure  Counott. This shMetabotropic GluR2s are located presynaptically on glutamatergic synapses and their activation reduces the probability of glutamate release. Thereby, an upregulation of mGluR2 levels diminishes activity of excitatory glutamatergic synapses in the PFC. Thus, increases in functional nAChR on inhibitory neurons and increased nicotine-stimulated excitation in deep layers of the PFC may be counteracted by reduced excitatory synaptic activity mediated by increased mGluR2 activity. Blocking mGluR2s with MPPG restored spike-timing-dependent potentiation following nicotine exposure during adolescence back to levels observed in animals that received saline treatment during adolescence  nAChRs in deep layers. The latter effect, however, is most likely counteracted by elevated presynaptic mGluR2 levels. This general increase in inhibition plays a role in the plasticity and refinement of cortical connections (reduced STDP in nicotine) and thus may have functional implications for cognitive processing and maturation of prefrontal network.Smoking during adolescence is associated with disturbances in working memory and attention as well as reduced PFC activation  is reduced in adult animals as a result of nicotine exposure during adolescence (Counotte et al., in vivo whole-cell recordings in cortical neurons during whisker deflection directly demonstrated that synaptic depression of thalamic input to the cortex contributes to rapid adaptation of sensory responses (Chung et al., STD may equip the synapse with low-pass filtering properties, by which the synapse will pass on the first of stimulus in a train of stimuli unaltered, while the rest are attenuated. In this manner it shapes the information transfer by synaptic networks and gives rise to sensory and behavioral phenomena Zucker, . For exaWe recently found that glutamatergic synapses in the PFC show increased spike-timing-dependent LTP 5 weeks after nicotine exposure during adolescence Figure  Gorioun. This waWhat is the mechanism underlying the long-term effects of nicotine exposure during adolescence on STDP? We hypothesized that altered levels of mGluR2 receptors can explain the lasting effects on STDP. Reduced mGluR2 signalling in adult rats after nicotine exposure (Counotte et al., STDP depends on the precise timing of the synaptic input and the postsynaptic action potential and this temporal relationship resembles typical features of associative learning (Letzkus et al., The prefrontal cortex, the brain area responsible for executive functions and attention performance, is one of the last brain areas to mature and is still in the process of developing during adolescence. This places the adolescent brain in a vulnerable state of imbalance, susceptible to the influence of psychoactive substances such as nicotine. In prefrontal networks nicotine modulates information processing on multiple levels by activating and desensitizing nicotine receptors on different cell types and in this way affects cognition. The adolescent brain is particularly sensitive to the effects of nicotine. Studies in human subjects indicate that smoking during adolescence increases the risk of developing psychiatric disorders and cognitive impairment in later life. In addition, adolescent smokers suffer from attention deficits, which progress with the years of smoking.From studies in the rodent brain it is becoming clear that on the short-term, adolescent, but not adult, nicotine exposure increases the expression of nAChRs containing α4 and β2 subunits in the mPFC, which leads to an increase in nicotine-induced GABAergic synaptic transmission. In addition, mGluR2 levels on presynaptic glutamatergic terminals in the PFC are increased, causing a reduction in glutamatergic synapse strength and reducing STDP Figure . ChangesNew questions and opportunities arise from these recent findings. The long-term adaptations involving mGluR2s can have profound implications for network functioning and affect more complex levels of information processing. What are the steps that lead from nicotine exposure and nAChR activation in the adolescent brain to adaptations in synaptic mGluR2 levels? Unveiling the signaling routes involved may provide a broader view on the adaptation strategies used during brain development in response to environmental factors. Another interesting question would be whether mGluR2 signaling is involved in a broader spectrum of attention impairments with different etiology. If changes in mGluR2 signaling are a common underlying mechanism for attention malfunction it would make it a suitable pharmacological target for therapy.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.


Acute variceal bleeding (AVB) is a life-threatening complication in patients with cirrhosis. Hemostatic therapy of AVB includes early administration of vasoactive drugs that should be combined with endoscopic therapy, preferably banding ligation. However, failure to control bleeding or early rebleed within 5 days still occurs in 15–20% of patients with AVB. In these cases, a second endoscopic therapy may be attempted  or we can use a balloon tamponade as a bridge to definitive derivative treatment . Esophageal balloon tamponade provides initial control in up to 80% of AVB, but it carries a high risk of major complications, especially in cases of long duration of tamponade (>24 h) and when tubes are inserted by inexperienced staff. Preliminary reports suggest that self-expandable covered esophageal metallic stents effectively control refractory AVB  with a low incidence of complications. Thus, covered self-expanding metal stents may represent an alternative to the Sengstaken-Blakemore balloon for the temporary control of bleeding in treatment failures. Further studies are required to determine the role of this new device in AVB. Acute variceal bleeding (AVB) is a severe complication of portal hypertension causing 70% of all upper gastrointestinal bleeding episodes in patients with portal hypertension . BleedinTherapy of AVB should be aimed at correcting hypovolemia, preventing complications associated with gastrointestinal bleeding, and achieving hemostasis. Therefore, after initial general management including resuscitation, airway protection, and prevention of potential complications (including administration of prophylactic antibiotics), we must proceed to provide specific therapy and to confirm the diagnosis of the source of bleeding by emergency endoscopy, which should be performed within 12 hours from arrival to hospital. Primary therapy of AVB includes early administration of vasoactive drugs  that should be combined with endoscopic therapy preferably esophageal banding ligation (EBL) once emergency endoscopy confirms bleeding from varices .  FigureIn 10 to 20% of patients, AVB is not controlled with this primary endoscopic and pharmacological therapy (failure to control bleeding or early rebleeding) . To reduce the incidence of treatment failure and death, more aggressive therapies may be used in patients at high risk of treatment failure. In this sense, a recent randomized controlled trial has shown that early transjugular intrahepatic portosystemic shunt (TIPS) using PTFE-covered stents within 72 hours (preferably within ≤24 hours) markedly reduced treatment failure as well as short-term and 1-year mortality in high-risk patients (those Child class C < 14 points or Child with active bleeding despite being vasoactive drug therapy). Control patients received the standard therapy plus rescue TIPS in case of treatment failure. The Baveno V consensus conference recommended that “early >TIPS should be considered in patients at high risk of treatment failure  after initial endoscopic and pharmacological therapy” .Experts agree that TIPS with PTFE-coated stents is the treatment of choice in most patients who fail medical and endoscopic therapy . HoweverBalloon tamponade is aimed at obtaining hemostasis by direct compression of the bleeding varices. The type of the balloon varies according to the site of bleeding: the Linton-Nachlas tube in gastric fundal varices and the Sengstaken-Blakemore tube  in esophIn this context, preliminary studies have evaluated the use of self-expandable covered esophageal metallic stents as an alternative to balloon tamponade for the temporary control of bleeding in treatment failures.The SX-Ella Danis stent  is a removable, covered, and self-expanding metal stent that can be deployed in the lower esophagus without radiological or endoscopic assistance . The steInitial studies came from the center who developed the technique. Hubmann and coworkers reported the results in 20 patients with massive ongoing bleeding despite previous endoscopic treatment or balloon tamponade . InteresA group of British investigators published their experience in 10 patients with variceal hemorrhage with contraindications to TIPS insertion  or balloon tamponade  . The SX-Potential indications for esophageal stenting not only relate to refractory variceal bleeding but also to cover large esophageal tears , 13, maiSince the SX-Ella Danis stent could remain in place up to 7 days (and has been used for up to 14 days) –13, thisIf safety is confirmed in large series, it could also be proposed to use esophageal stents earlier in the course of bleeding, before declaring it “refractory” to standard therapy .Gastric varices will not be adequately compressed by the stent whereas the gastric balloon of the Sengstaken-Blakemore tube may have a role in some patients (GOV1 and some cases of GOV2). Nevertheless, it should be considered that most fundal varices (IGV1 and the majority of GOV2) will not be correctly treated by either the SX-Ella Danis stent or the Sengstaken-Blakemore tube. In these cases, endoscopic obturation with bucrylate is indicated, and tamponade with a Linton-Nachlas tube may be used in failures as a bridge to TIPS.In patients with massive bleeding, in whom esophageal stent was deployed without previous diagnostic endoscopy, the persistence of bleeding strongly raises the suspicion of bleeding gastric varices . In thesAlthough both balloon tamponade and esophageal stenting could be deployed at the emergency room or the endoscopy room, the characteristics of the patients requiring such therapies advise to admit them to an intensive surveillance facility  attended by experienced physicians and nurses.In this sense, it should be noted that therapy of ABV is not only directed at achieving hemostasis, but also at preventing bleeding-related complications  , 3.The technical requirements to insert either a Sengstaken-Blakemore tube or an SX-Ella Danis stent are scarce. In fact, both devices could be inserted and inflated/deployed without radiological or endoscopic assistance. It should be taken into account that most of the published cases of esophageal stents to treat AVB were deployed in the lower esophagus over an endoscopically placed guide wire –12 althoAfter the placement of both the balloon or the stent, a chest radiograph must be taken to confirm that the device is correctly positioned.As previously mentioned, balloon tamponade can be associated with severe complications the most dreadful being esophageal perforation . UsuallyTo avoid this often lethal complication, the SX-Ella Danis stent has a security pressure valve that does not allow the gastric balloon being inflated against resistance. This minimizes the risk of esophageal perforation in inexperienced hands. Moreover, as some authors described , 13, theFortunately, esophageal perforation is not the most frequent complication of balloon tamponade. This first position is reserved for aspiration pneumonia. The high incidence of this complication (47% in our unit) leads to the recommendation of protecting the patient's airway by means of endotracheal intubation whenever a Sengstaken-Blakemore tube is in place. Aspiration in many cases occurs during placement of the Sengstaken-Blakemore tube in an actively bleeding patients; in others, it is due to the fact that supraglottic secretions accumulate over the esophageal balloon and enter the tracheobronchial tree despite the presence of an esophageal aspiration port . EsophagIn addition, the presence of an esophageal stent is not a problem for maintaining oral nutrition, which is an essential component for the recovery of the patients.According to reported data, the experts meeting at the Baveno V consensus conference agreed that “uncontrolled data suggest that self-expanding covered esophageal metal stent may be an option in refractory esophageal variceal bleeding” . It shouNevertheless, further studies, preferably randomized controlled trials, are required to determine the role of covered self-expanding metal stents in acute variceal bleeding.


BackgroundAsthma requires individually tailored and careful management to control and prevent symptoms and exacerbations. Selection of the most appropriate treatment is dependent on both the choice of drugs and inhaler device; however, financial pressures may result in patients being switched to alternative medications and devices in an attempt to reduce costs.AimThis review aimed to examine the published literature in order to ascertain whether switching a patient’s asthma medications or device negatively impacts clinical and economic outcomes.Materials and methodsA literature search of MEDLINE (2001–13 September 2011) was conducted to identify English-language articles focused on the direct impact of switching medications and inhaler devices and switching from fixed-dose combination to monocomponent therapy via separate inhalers in patients with asthma; the indirect impacts of switching were also assessed.ResultsEvidence showed that non-consented switching of medications and inhalers in patients with asthma can be associated with a range of negative outcomes, at both individual and organisational levels. Factors that reduce adherence may lead to compromised symptom control resulting in increased healthcare resource utilisation and poorer patient quality of life.DiscussionThe consequences of a non-consented switch should be weighed carefully against arguments supporting an inhaler switch without the patient’s consent for non-medical/budgetary reasons, such as potential reductions in initial acquisition costs, which may be associated with subsequent additional healthcare needs.ConclusionGiven the increasing pressure for reduced costs and efficient allocation of limited healthcare resources, an additional investment in ensuring high medication adherence may lead to greater savings due to a potentially decreased demand for healthcare services. In contrast, savings achieved in acquisition costs may result in a greater net loss due to increased healthcare consumption caused by decreased asthma control. A literature search of the MEDLINE database was conducted to identify English-language articles with content specific to the direct impact of switching medications and inhaler devices and switching from fixed-dose combination to monocomponent therapy via separate inhalers in patients with asthma; the indirect impacts of switching were also assessed. Conference abstracts were not included.Switching medications and inhaler devices in patients with asthma without their consent or a medical need can result in increased demand for healthcare services. Prescribers should, therefore, not only consider the acquisition costs that may be potentially reduced by switching patients to lower cost products but also the potential subsequent costs of additional healthcare needs.Asthma is a complex disease requiring careful and individually tailored treatment There are a large variety of inhaler devices available, and differences in design, handling technique, durability (i.e. shelf-life) and price between branded and analogue products can be great. Successful management of asthma symptoms is dependent on a number of factors Figure–. One keyNon-consented switching means that patients do not receive any counselling from their healthcare provider about the new medication and device, which may result in poor inhalation technique. This can negatively impact adherence and asthma control, and evidence suggests that treating asthma medications as interchangeable on an interclass basis can have detrimental effects on patient outcomes The objective of this review, which primarily focused on dry powder inhalers (DPIs), was to review the published literature to obtain a clearer picture regarding whether switching a patient’s asthma medications or device negatively impacts clinical and economic outcomes.Data were derived from published English-language papers listed in MEDLINE, and accessed via PubMed according to defined search terms. Searches were limited to full publications only; conference abstracts were not included. Only articles published between 2001 and 13 September 2011 were included. Three different searches were performed using keywords to identify publications that focused on:Monocomponents vs. fixed-dose combination (FDC) therapy: searches combined the terms bronchodilator and inhaled corticosteroids (ICS), asthma, single inhaler and combination inhaler.Consequences of switching devices: searches combined the terms bronchodilator and ICS, asthma, FDC or free-combination therapy, switching, device or inhaler , adherence or compliance, asthma or symptom control and healthcare utilisation or costs.Adherence, cost-effectiveness and quality of life: searches combined the terms bronchodilator agents or ICS or glucocorticoid, adherence or compliance, cost-effectiveness or cost or health economics, quality of life, device or inhaler, training or technique or education or instruction, fixed or combination therapy or single inhaler therapy or separate inhaler or FDC or free combination or monotherapy or monocomponents and asthma. Resource use and resource utilisation were not included as search terms. This search was also limited to articles published between 2001 and 13 September 2011.Abstracts of the articles identified via the three searches were analysed for content specific to the following topics:Direct impact of switching, including switching from combination therapy to monotherapyPharmaceutical performanceInhalation techniqueAdherenceAsthma controlIndirect impact of switchingHealthcare resource consumption and costs.The direct impact of switching has implications for pharmaceutical performance, inhalation technique and adherence, all factors that ultimately affect asthma control and quality of life Currently, there are a large number of DPIs available; these devices differ greatly in their design and features Dry powder inhalers also differ with respect to inhalation technique. Correct technique is critical for delivering the correct drug dose to the airways, and patient education is crucial Successful switching requires instruction on the correct inhaler technique and regular monitoring; incorrect use of a device is one of the most frequent concerns patients express after switching When a patient follows an instruction leaflet, the first attempt to use a new device is often unsuccessful with a high probability of handling errors Adherence to treatment is essential for optimal asthma control; however, studies indicate that patients are poorly adherent and generally underuse their asthma medications It is important that prescribers consider patient needs and preferences when choosing the most appropriate treatment choice as these factors contribute greatly to adherence Adherence is also dependent on several non-drug- or -device-related factors, including patient–physician partnership and level of patient satisfaction with their device 2-agonists (LABA) compared with ICS plus LABA administered via separate inhalers, as a true double-dummy technique is not possible. However, data from an open-label, randomised study and two retrospective observational analyses show that adherence tends to be higher with FDCs administered via a single inhaler rather than monocomponents via separate inhalers Few studies have directly assessed adherence to FDCs of ICS/long-acting βn–=–19) The consequences of a non-consented inhaler switch were assessed qualitatively by Doyle et–al. via semi-structured face-to-face interviews with patients (n–=–499) from Australia, Canada, France, Germany and the UK using a Delphi process Important themes associated with interchangeability of DPIs were identified in a survey of asthma patients or parents of children aged 5–14–years with asthma  Reduced medication adherence is directly related to reduced asthma control The increased probability of handling errors resulting from unfamiliar inhalation techniques may also result in reduced asthma control as a result of under-dosing The causal relationship between poor device handling and poor asthma control has been investigated in two studies Non-adherence leads to numerous adverse events associated with uncontrolled asthma Non-consented switching and switching for non-medical reasons can have direct negative effects on disease control, resulting in increased healthcare resource consumption and costs The difference in costs of scheduled and unscheduled asthma healthcare visits in Europe was estimated by Williams et–al. In other chronic diseases, FDC therapies have been shown to improve adherence compared with individual monocomponents, thereby improving disease control The causal chain of events discussed above, and outlined in Figure–To conclude, given the continually increasing pressure for reduced costs and efficient allocation of limited healthcare resources, an additional investment in ensuring high medication adherence may lead to greater savings because of potentially decreased demand for healthcare services. In contrast, savings achieved in acquisition costs may result in a greater net loss because of increased healthcare consumption, caused by decreased asthma control.