Usefulness of sputum gram stain for etiologic diagnosis in community-acquired pneumonia: a systematic review and meta-analysis

Background: implementation of sputum Gram stain in the initial assessment of community-acquired pneumonia (CAP) patients is still controversial. We performed a systematic review and meta-analysis to investigate the usefulness of sputum Gram stain for defining the etiologic diagnosis of CAP in adult patients. Methods: we systematically searched the Medline, Embase, Science Direct, Scopus and LILACS databases for full-text articles. Relevant studies were reviewed by at least three investigators who extracted the data, pooled them using a random effects model, and carried out quality assessment. For each bacterium (Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, and Gram-negative bacilli), pooled sensitivity, specificity, positive and negative likelihood ratios were reported. Results: after a review of 3539 abstracts, 20 articles were included in the present meta-analysis. The studies included yielded 5619 patients with CAP. Pooled sensitivity and pooled specificity of sputum Gram stain were 0.59 (95% CI, 0.56-0.62) and 0.87 (95% CI, 0.86-0.89) respectively for S. pneumoniae, 0.78 (95% CI, 0.72-0.84) and 0.96 (95% CI, 0.94-0.97) for H. influenzae, 0.72 (95% CI, 0.53-0.87) and 0.97 (95% CI, 0.95-0.99) for S. aureus, and 0.64 (95% CI, 0.49-0.77) and 0.99 (95% CI, 0.97-0.99) for Gram-negative bacilli. Conclusion: Sputum Gram stain test is sensitive and highly specific for identifying the main causative pathogens in adult patients with CAP

The Basolateral Amygdala Is Essential for Rapid Escape: A Human and Rodent Study.

Rodent research delineates how the basolateral amygdala (BLA) and central amygdala (CeA) control defensive behaviors, but translation of these findings to humans is needed. Here, we compare humans with natural-selective bilateral BLA lesions to rats with a chemogenetically silenced BLA. We find, across species, an essential role for the BLA in the selection of active escape over passive freezing during exposure to imminent yet escapable threat (T <sub>imm</sub> ). In response to T <sub>imm</sub> , BLA-damaged humans showed increased startle potentiation and BLA-silenced rats demonstrated increased startle potentiation, freezing, and reduced escape behavior as compared to controls. Neuroimaging in humans suggested that the BLA reduces passive defensive responses by inhibiting the brainstem via the CeA. Indeed, T <sub>imm</sub> conditioning potentiated BLA projections onto an inhibitory CeA pathway, and pharmacological activation of this pathway rescued deficient T <sub>imm</sub> responses in BLA-silenced rats. Our data reveal how the BLA, via the CeA, adaptively regulates escape behavior from imminent threat and that this mechanism is evolutionary conserved across rodents and humans

A consensus protocol for functional connectivity analysis in the rat brain

Task-free functional connectivity in animal models provides an experimental framework to examine connectivity phenomena under controlled conditions and allows for comparisons with data modalities collected under invasive or terminal procedures. Currently, animal acquisitions are performed with varying protocols and analyses that hamper result comparison and integration. Here we introduce StandardRat, a consensus rat functional magnetic resonance imaging acquisition protocol tested across 20 centers. To develop this protocol with optimized acquisition and processing parameters, we initially aggregated 65 functional imaging datasets acquired from rats across 46 centers. We developed a reproducible pipeline for analyzing rat data acquired with diverse protocols and determined experimental and processing parameters associated with the robust detection of functional connectivity across centers. We show that the standardized protocol enhances biologically plausible functional connectivity patterns relative to previous acquisitions. The protocol and processing pipeline described here is openly shared with the neuroimaging community to promote interoperability and cooperation toward tackling the most important challenges in neuroscience

OXYTOCIN FACILITATES AVOIDANCE LEARNING BY REDUCTION OF FREEZING RESPONSES IN A CORTICO- AMYGDALOID CIRCUIT

When we come across a possible danger, the brain circuits that encode emotional responses of fear will react to increase the chances for survival. Depending on the proximity of danger (distant or imminent), we will chose either to freeze or to escape and avoid the threat, a decision that can be influenced by our anxiety levels. But how do we choose, or decide, whether to escape or to stay paralyzed?, variability in behavioural traits can be explained in terms of modulation and functional connectivity between the prefrontal cortex and the amygdala, two brain areas known to modulate the salience of emotions like fear. By the use of a test in which rats learned to avoid threats, two behavioural populations were formed according with their avoidance success: high avoiders/low freezers and low avoiders/ high freezers. Using fMRI and behavioural test, I further characterized these populations to know their innate traits of anxiety and sociability before the avoidance conditioning. After the avoidance conditioning, I observed a potentiation in resting state fMRI networks and functional connectivity (amygdala and prefrontal cortex) in low avoiders, compared with high avoiders and non trained animals. This network potentiation was stronger in low avoiders, with higher scores in freezing, anxiety and lower scores in sociability. Then, knowing that oxytocin mediates inhibition of amygdala and prefrontal cortex, I sought to uncover the modulatory and plastic mechanism for which oxytocin, favours avoidance or escape behaviour upon suppression of freezing. I found out that oxytocin stimulates GABAerigic neurons in these areas, and can make a switch from passive (freezing) to active (avoidance) coping strategies, in animals that have learned to avoid threats. Moreover, in the central amygdala I observed that a synaptic potentiation on cells expressing the oxytocin receptor underlies successful avoidance learning. From there, I targeted the learning phase of avoidance, and observed that oxytocin is necessary to acquire avoidance behaviours by the suppression of freezing responses, in the amygdala and prelimbic cortex. Such influence in avoidance learning is underlined by oxytocin-dependent long-term synaptic potentiation in central amygdala. Overall, this study showed a modulatory and plastic mechanism through which oxytocin increased active coping at suppressing freezing. These findings could be applied in the future as therapeutical targets for fear and anxiety disorders. -- Lorsque nous rencontrons un danger potentiel, les circuits cérébraux qui codent les réponses émotionnelles de la peur vont réagir pour augmenter les chances de survie. Selon la proximité du danger (lointain ou imminent), nous choisirons soit de rester immobile, soit de fuir et d'éviter la menace. Cette décision peut être influencée par notre niveau d'anxiété. Mais comment choisir, décider, de s'échapper ou de rester immobile ? La variabilité des traits comportementaux s'explique en termes de modulation et de connectivité fonctionnelle entre le cortex préfrontal et l'amygdale, deux zones du cerveau connues pour moduler l'importance des émotions comme la peur. En utilisant un test comportemental au cours duquel les rats apprennent à éviter les menaces, on observe deux profils comportementaux en fonction de leur succès d’évitement : les Low avoiders (LA) dont le capacité à fuir est faible et le comportement d’immobilité élevé (freezing) et Les high avoiders (LA) caractérisés par haute capacité à fuir. En utilisant l'IRMf et des tests comportementaux, nous avons évalué ces deux profils pour connaître leurs niveaux d'anxiété constitutifs et de sociabilité avant de les conditionner au test l'évitement actif de la peur. Après le conditionnement d'évitement, nous avons observé avec l'IRMf, une potentialisation des réseaux, en comparaison avec l'état de repos et une connectivité fonctionnelle entre l’amygdale et le cortex préfrontal chez les LA par rapport aux HA et aux animaux non entraînés. Cette potentialisation du réseau est plus forte chez les individus (LA) qui évitent peu, avec des scores plus élevés pour le freezing et l'anxiété, et des scores plus faibles pour la sociabilité. Puis, sachant que l'ocytocine intervient dans l'inhibition de l'amygdale et du cortex préfrontal, nous avons cherché à découvrir le mécanisme modulatoire et plastique par lequel ce neurotransmetteur favorise les comportements d'évitement ou d'échappement lors de la suppression du freezing. Nous avons découvert que l'ocytocine stimule les neurones GABAerigic dans ces régions, et qu'elle peut permettre de passer de stratégies passives (freezing) à des stratégies actives (évitement). De plus, dans l'amygdale centrale, Nous avons observé qu'une potentialisation synaptique sur les cellules exprimant le récepteur de l'ocytocine sous-tend un apprentissage réussi de l'évitement. A la suite de cela, nous avons ciblé la phase d'apprentissage de l'évitement, et j'ai observé que l'ocytocine est nécessaire pour acquérir des comportements d'évitement par la suppression des réponses de freezing, dans l’amygdale et le cortex prélimbique. Une telle influence dans l'apprentissage de l'évitement est soulignée par la potentialisation synaptique à long terme dépendant de l'ocytocine dans l'amygdale centrale. Dans l'ensemble, cette étude a montré un mécanisme modulateur et plastique par lequel l'ocytocine augmente la capacité d'adaptation en faveur d’un comportement actif couplé avec la suppression du comportement de freezing. Ces résultats pourraient être utilisés à l'avenir comme cibles thérapeutiques pour la peur et les troubles anxieux. -- When we come across a possible danger, the brain circuits that encode emotional responses of fear will react to increase the chances for survival. Depending on the proximity of danger (distant or imminent), we will chose either to freeze or to escape and avoid the threat, a decision that can be influenced by our anxiety levels. But how do we choose, or decide, whether to escape or to stay paralyzed? Variability in behavioural traits can be explained in terms of connectivity between brain areas known to modulate emotions like fear, some of these areas are the amygdala and the prefrontal cortex. I my thesis I first trained animals to avoid dangers, some animals were very good at doing it (high avoiders), as they never get paralyzed by their fear; the others were always paralyzed and were not good at avoiding the danger (low avoiders). I wanted to know more about these animal populations and I discovered that the animals that paralyzed often with fear (low avoiders) are animals with innate predisposition for high anxiety and low sociability. In addition, by doing images of their brains after avoidance training, low avoiders showed more activity and connectivity in amygdala and prefrontal cortex. Then I used oxytocin, which is a molecule that decreases anxiety and increases sociability, to modulate the avoidance behaviour of different rats in the amygdala amd prefrontal cortex. Oxytocin in these areas can make a switch from passive (freezing) to active (avoidance) behaviours, by modulating the inhibition of those areas (very activated in anxious subjects). In addition, successful avoidance learning potentiated the oxytocin connections in the amygdala, which lead me to think that oxytocin may mediate avoidance learning and consolidation itself. Then I discovered that oxytocin is necessary for the learning of avoidance behaviour in the amygdala and the prefrontal cortex, by the suppression of freezing. This effect depends of the strengthening of connections (synapses) in the cells that react to oxytocin in the central amygdala. Overall, I found that there is a variability to react to danger that can be explained by the modulation of oxytocin in the amygdala and the prefrontal cortex, as well as by innate levels of anxiety and sociability. Oxytocin seems important for the learning, consolidation and expression of avoidance behaviour upon freezing suppression, a mechanism that could be potentially used to treat fear and anxiety disorders. -- Lorsque nous rencontrons un danger possible, les circuits cérébraux qui codent les réponses émotionnelles de la peur vont réagir pour augmenter les chances de survie. Selon la proximité du danger (lointain ou imminent), nous choisirons soit de s’immobiliser, soit de fuir et d'éviter la menace, une décision qui peut être influencée par notre niveau d'anxiété. Mais comment choisir, décider, de s'échapper ou de rester? La variabilité des réponses comportementales au sein d’un groupe d’individus, peut s'expliquer par la connectivité entre différentes zones du cerveau connues pour moduler les émotions comme la peur . On retrouve parmi celle-ci l'amygdale et le cortex préfrontal. Dans ma thèse, j'ai d'abord appris à des animaux à éviter le danger, certains animaux étaient très doués pour le faire (High escapers), car ils ne sont jamais paralysés par leur alors que d’autres restaient toujours paralysés et ne prenaient jamais la fuite (low escapers). Je voulais en savoir plus sur ces populations et j'ai découvert que les animaux qui restent paralysés par la peur (ceux qui évitent peu) sont également prédisposé à présenter une forte anxiété et une faible sociabilité. De plus, en faisant des images de leur cerveau à la suite d’un apprentissage d'évitement, les low escapers ont montré plus d'activité et de connectivité dans l'amygdale et le cortex préfrontal. J'ai ensuite utilisé l'ocytocine, une molécule qui diminue l'anxiété et augmente la sociabilité, pour moduler au niveau de l’amygdale et du cortex préfrontal le comportement d'évitement des différents types de rats. L'ocytocine injectée dans ces zones entraine des modifications de comportement, passant d’un comportement passif (immobilité) à actif (évitement), en modulant l'inhibition de ces zones (très activé chez les sujets anxieux). De plus, un apprentissage d'évitement réussi potentialise les connexions de l'ocytocine dans l'amygdale, ce qui laisse penser que l'ocytocine peut servir de médiateur pour l'apprentissage et la consolidation de l'évitement. J'ai finalement mis en évidence que l'ocytocine est nécessaire à l'apprentissage d'évitement dans l'amygdale et le cortex préfrontal, par la suppression du comportement d’immobilité. Cet effet dépend du renforcement des connexions (synapses) dans les cellules qui réagissent à l'oxytocine dans l'amygdale centrale. Dans l'ensemble, il existe une variabilité de réponses au danger qui peut s'expliquer par la modulation de l'oxytocine au niveau de l’amygdale et du cortex préfrontal, ainsi que par des niveaux d'anxiété et de sociabilité différents. Pour résumé, l'ocytocine semble importante pour l'apprentissage, la consolidation et l'expression du comportement d'évitement couplé à la suppression du comportement d immobilité, un mécanisme qui pourrait être potentiellement utilisé pour traiter les troubles anxieux et la peur

El comportamiento homosexual y sus bases neurales

Objective: Redefine the concept of homosexual behavior and its neural bases, and to discuss the role of conditioning on learnt homosexual behaviors. Development: We propose a behavioral continuum in which animals and humans may display appetitive, precopulatory, consummatory or postconsummatory homosexual behaviors with variable intensity and duration. We discuss the role of brain dimorphism on sexual behavior and partner preference. In addition, we show evidence indicating that animals may display learnt social preferences that switch into homosexual preferences if they spent sufficient time of cohabitation with an individual of the same sex under the effect of dopamine type D2 agonists. Conclusion: The evidence in this article suggests that homosexual behavior may be subtle or explicit, transitory or long-lasting, as a result of the computation that results from the activity of neurocircuitries organized by hormones during perinatal periods and by learning during later periods of life.Objetivo: Redefinir el concepto de comportamiento homosexual analizando sus bases apetitivas, precopulatorias, consumatorias y posconsumatorias; así como analizar las bases neurales y el papel del aprendizaje en el comportamiento homosexual. Desarrollo: Proponemos un continuum comportamental con el cual los humanos y animales muestran comportamientos homosexuales de expresión y duración variable. Se discute el papel del dimorfismo sexual del cerebro y la evidencia que lo correlaciona con el comportamiento y las preferencias sexuales. También se muestra evidencia reciente que sugiere que a través del condicionamiento, los animales pueden desplegar preferencias que pasan de lo social a lo homosexual de manera temporal si pasaron suficiente tiempo junto a la pareja del mismo sexo, bajo la influencia de agonistas para el receptor de dopamina tipo D2. Conclusión: la discusión en este artículo sugiere que el comportamiento homosexual puede ocurrir de manera sutil o explícita, temporal o permanentemente, dependiendo del cálculo que resulta de la actividad de neurocircuitos organizados por hormonas en periodos perinatales junto con aquellos circuitos organizados por el aprendizaje en periodos posteriores

Social buffering in rats reduces fear by oxytocin triggering sustained changes in central amygdala neuronal activity.

The presence of a companion can reduce fear, but the neural mechanisms underlying this social buffering of fear are incompletely known. We studied social buffering of fear in male and female, and its encoding in the amygdala of male, auditory fear-conditioned rats. Pharmacological, opto,- and/or chemogenetic interventions showed that oxytocin signaling from hypothalamus-to-central amygdala projections underlied fear reduction acutely with a companion and social buffering retention 24 h later without a companion. Single-unit recordings with optetrodes in the central amygdala revealed fear-encoding neurons (showing increased conditioned stimulus-responses after fear conditioning) inhibited by social buffering and blue light-stimulated oxytocinergic hypothalamic projections. Other central amygdala neurons showed baseline activity enhanced by blue light and companion exposure, with increased conditioned stimulus responses that persisted without the companion. Social buffering of fear thus switches the conditioned stimulus from encoding "fear" to "safety" by oxytocin-mediated recruitment of a distinct group of central amygdala "buffer neurons"

Social buffering in rats reduces fear by oxytocin triggering sustained changes in central amygdala neuronal activity

Abstract The presence of a companion can reduce fear, but the neural mechanisms underlying this social buffering of fear are incompletely known. We studied social buffering of fear in male and female, and its encoding in the amygdala of male, auditory fear-conditioned rats. Pharmacological, opto,- and/or chemogenetic interventions showed that oxytocin signaling from hypothalamus-to-central amygdala projections underlied fear reduction acutely with a companion and social buffering retention 24 h later without a companion. Single-unit recordings with optetrodes in the central amygdala revealed fear-encoding neurons (showing increased conditioned stimulus-responses after fear conditioning) inhibited by social buffering and blue light-stimulated oxytocinergic hypothalamic projections. Other central amygdala neurons showed baseline activity enhanced by blue light and companion exposure, with increased conditioned stimulus responses that persisted without the companion. Social buffering of fear thus switches the conditioned stimulus from encoding “fear” to “safety” by oxytocin-mediated recruitment of a distinct group of central amygdala “buffer neurons”

Cómo aprender a comportarse� sexualmente

Learning can affect many aspects of sexual behavior. Learning may increase or decrease an animal´s sensitivity to respond to internal and external stimuli which trigger its own sexual desire and indicate who is a potencial mate and what a sexual incentive is. This occurs as a result of two learning mechanisms, Pavlovian Conditioning and Instrumental (operant) conditioning. With the former, individuals learn to associate neutral stimuli with unconditioned responses, and therefore the stimuli may become conditioned, with the potential to predict sex and unconsciously may guide our sexual preferences. With Instrumental conditioning, an individual learns how to behave to obtain a certain response, which may help explain how non-sexual behavior may become so if they predict sex. In this paper we discuss the effects of learning in critical periods of life when individuals are more sensitive to become conditioned, and therefore learn to behave sexually.A través del aprendizaje, los individuos pueden incrementar o disminuir de manera eficiente sus respuestas a estímulos internos (como las hormonas) o externos (señales del ambiente) que pueden desencadenar el deseo sexual e indicar quién es una pareja potencial para aparearse. Así mismo, el aprendizaje modifica el valor incentivo de las características de los individuos que se consideran atractivos o no. Esto ocurre principalmente a través de dos mecanismos: el condicionamiento Pavloviano y el Instrumental (operante). En el primero, los individuos aprenden a asociar estímulos neutros con respuestas incondicionadas, los cuales eventualmente se convierten en estímulos condicionados que predicen el evento sexual, y de manera inconsciente guían nuestras preferencias. En el segundo, los individuos aprenden a comportarse y a obtener una respuesta condicionada, lo cual pudiera explicar muchos rituales de cortejo en animales y humanos. En este artículo detallamos los efectos del aprendizaje desde la etapa perinatal hasta la edad adulta, haciendo énfasis en las etapas críticas en las cuales los individuos aprenden a comportarse sexualmente

An AAV-CRISPR/Cas9 strategy for gene editing across divergent rodent species: Targeting neural oxytocin receptors as a proof of concept

A major issue in neuroscience is the poor translatability of research results from preclinical studies in animals to clinical outcomes. Comparative neuroscience can overcome this barrier by studying multiple species to differentiate between species-specific and general mechanisms of neural circuit functioning. Targeted manipulation of neural circuits often depends on genetic dissection, and use of this technique has been restricted to only a few model species, limiting its application in comparative research. However, ongoing advances in genomics make genetic dissection attainable in a growing number of species. To demonstrate the potential of comparative gene editing approaches, we developed a viral-mediated CRISPR/Cas9 strategy that is predicted to target the oxytocin receptor (Oxtr) gene in >80 rodent species. This strategy specifically reduced OXTR levels in all evaluated species (n = 6) without causing gross neuronal toxicity. Thus, we show that CRISPR/Cas9-based tools can function in multiple species simultaneously. Thereby, we hope to encourage comparative gene editing and improve the translatability of neuroscientific research