RESUMEN
Individual testing of samples is time- and cost-intensive, particularly during an ongoing pandemic. Better practical alternatives to individual testing can significantly decrease the burden of disease on the healthcare system. Herein, we presented the clinical validation of Segtnan™ on 3929 patients. Segtnan™ is available as a mobile application entailing an AI-integrated personalized risk assessment approach with a novel data-driven equation for pooling of biological samples. The AI was selected from a comparison between 15 machine learning classifiers (highest accuracy = 80.14%) and a feed-forward neural network with an accuracy of 81.38% in predicting the rRT-PCR test results based on a designed survey with minimal clinical questions. Furthermore, we derived a novel pool-size equation from the pooling data of 54 published original studies. The results demonstrated testing capacity increase of 750%, 60%, and 5% at prevalence rates of 0.05%, 22%, and 50%, respectively. Compared to Dorfman's method, our novel equation saved more tests significantly at high prevalence, i.e., 28% (p = 0.006), 40% (p = 0.00001), and 66% (p = 0.02). Lastly, we illustrated the feasibility of the Segtnan™ usage in clinically complex settings like emergency and psychiatric departments.
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COVID-19 , Humanos , Prevalencia , Ahorro de Costo , Aprendizaje Automático , Medición de RiesgoRESUMEN
Adult-born cells, arriving daily into the rodent olfactory bulb, either integrate into the neural circuitry or get eliminated. However, whether these two populations differ in their morphological or functional properties remains unclear. Using longitudinal in vivo two-photon imaging, we monitored dendritic morphogenesis, odor-evoked responsiveness, ongoing Ca2+ signaling, and survival/death of adult-born juxtaglomerular neurons (abJGNs). We found that the maturation of abJGNs is accompanied by a significant reduction in dendritic complexity, with surviving and subsequently eliminated cells showing similar degrees of dendritic remodeling. Surprisingly, â¼63% of eliminated abJGNs acquired odor responsiveness before death, with amplitudes and time courses of odor-evoked responses similar to those recorded in surviving cells. However, the subsequently eliminated cell population exhibited significantly higher ongoing Ca2+ signals, with a difference visible even 10 days before death. Quantitative supervised machine learning analysis revealed a relationship between the abJGNs' activity and survival probability, with low neuronal activity being supportive for survival.
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Neuronas , Bulbo Olfatorio , Neuronas/fisiología , Interneuronas , Odorantes , Transducción de SeñalRESUMEN
The development and survival of adult-born neurons are believed to be driven by sensory signaling. Here, in vivo analyses of motility, morphology and Ca2+ signaling, as well as transcriptome analyses of adult-born juxtaglomerular cells with reduced endogenous excitability (via cell-specific overexpression of either Kv1.2 or Kir2.1 K+ channels), revealed a pronounced impairment of migration, morphogenesis, survival, and functional integration of these cells into the mouse olfactory bulb, accompanied by a reduction in cytosolic Ca2+ fluctuations, phosphorylation of CREB and pCREB-mediated gene expression. Moreover, K+ channel overexpression strongly downregulated genes involved in neuronal migration, differentiation, and morphogenesis and upregulated apoptosis-related genes, thus locking adult-born cells in an immature and vulnerable state. Surprisingly, cells deprived of sensory-driven activity developed normally. Together, the data reveal signaling pathways connecting the endogenous intermittent neuronal activity/Ca2+ fluctuations as well as enhanced Kv1.2/Kir2.1 K+ channel function to migration, maturation, and survival of adult-born neurons.
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Neuronas , Bulbo Olfatorio , Ratones , Animales , Bulbo Olfatorio/metabolismo , Neuronas/metabolismo , Neurogénesis/genética , Diferenciación Celular , Movimiento CelularRESUMEN
Intrinsic neuronal activity is a hallmark of the developing brain. In rodents, a handful of such activities were described in different cortical areas but the unifying macroscopic perspective is still lacking. Here we combined large-scale in vivo Ca2+ imaging of the dorsal cortex in non-anesthetized neonatal mice with mathematical analyses to reveal unique behavioral state-specific maps of intrinsic activity. These maps were remarkably stable over time within and across experiments and used patches of correlated activity with little hemispheric symmetry as well as stationary and propagating waves as building blocks. Importantly, the maps recorded during motion and rest were almost inverse, with frontoparietal areas active during motion and posterior-lateral areas active at rest. The retrosplenial cortex engaged in both resting- and motion-related activities via functional long-range connections with respective cortical areas. The data obtained bind different region-specific activity patterns described so far into a single consistent picture and set the stage for future inactivation studies, probing the exact function of this complex activity pattern for cortical wiring in neonates.
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Encéfalo , Neuronas , Animales , RatonesRESUMEN
Peripheral inflammation is known to impact brain function, resulting in lethargy, loss of appetite and impaired cognitive abilities. However, the channels for information transfer from the periphery to the brain, the corresponding signaling molecules and the inflammation-induced interaction between microglia and neurons remain obscure. Here, we used longitudinal in vivo two-photon Ca2+ imaging to monitor neuronal activity in the mouse cortex throughout the early (initiation) and late (resolution) phases of peripheral inflammation. Single peripheral lipopolysaccharide injection induced a substantial but transient increase in ongoing neuronal activity, restricted to the initiation phase, whereas the impairment of visual processing was selectively observed during the resolution phase of systemic inflammation. In the frontal/motor cortex, the initiation phase-specific cortical hyperactivity was seen in the deep (layer 5) and superficial (layer 2/3) pyramidal neurons but not in the axons coming from the somatosensory cortex, and was accompanied by reduced activity of layer 2/3 cortical interneurons. Moreover, the hyperactivity was preserved after depletion of microglia and in NLRP3-/- mice but absent in TNF-α-/- mice. Together, these data identify microglia-independent and TNF-α-mediated reduction of cortical inhibition as a likely cause of the initiation phase-specific cortical hyperactivity and reveal the resolution phase-specific impairment of sensory processing, presumably caused by activated microglia.
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Inflamación , Microglía , Animales , Ratones , Neuronas , Células Piramidales , Corteza SomatosensorialRESUMEN
The rodent olfactory bulb (OB) is continuously supplied with adult-born cells maturing into GABAergic neurons. Using in vivo ratiometric Ca2+ imaging to readout ongoing and sensory-driven activity, we asked whether mature adult-born cells (mABCs) in the glomerular layer of the bulb become functionally identical to resident GABAergic (ResGABA) neurons. In awake head-restrained mice the two cell populations differed significantly in terms of ongoing spontaneous activity, with 24% of mABCs contributing to a strongly active cell cluster, absent among ResGABA cells. Odor-evoked responses of mABCs were sparse, less reliable, and had smaller amplitudes compared with ResGABA cells. The opposite was seen under anesthesia, with response reliability increasing and response size of mABCs becoming larger than that of ResGABA cells. Furthermore, ongoing activity of mABCs showed increased sensitivity to ketamine/xylazine and was selectively blocked by the antagonist of serotonin receptors methysergide. These functional features of mABCs clearly distinguish them from other OB interneurons.
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Neuronas GABAérgicas/metabolismo , Interneuronas/metabolismo , Bulbo Olfatorio/metabolismo , Animales , Ratones , OdorantesRESUMEN
Throughout the lifespan, microglia, the primary innate immune cells of the brain, fulfill a plethora of homeostatic as well as active immune defense functions, and their aging-induced dysfunctionality is now considered as a key trigger of aging-related brain disorders. Recent evidence suggests that both organism's sex and age critically impact the functional state of microglia but in vivo determinants of such state(s) remain unclear. Therefore, we analyzed in vivo the sex-specific functional states of microglia in young adult, middle aged and old wild type mice by means of multicolor two-photon imaging, using the microglial Ca2 + signaling and directed process motility as main readouts. Our data revealed the sex-specific differences in microglial Ca2 + signaling at all ages tested, beginning with young adults. Furthermore, for both sexes it showed that during the lifespan the functional state of microglia changes at least twice. Already at middle age the cells are found in the reactive or immune alerted state, characterized by heightened Ca2 + signaling but normal process motility whereas old mice harbor senescent microglia with decreased Ca2 + signaling, and faster but disorganized directed movement of microglial processes. The 6-12 months long caloric restriction (70% of ad libitum food intake) counteracted these aging-induced changes shifting many but not all functional properties of microglia toward a younger phenotype. The improvement of Ca2 + signaling was more pronounced in males. Importantly, even short-term (6-week-long) caloric restriction beginning at old age strongly improved microglial process motility and induced a significant albeit weaker improvement of microglial Ca2 + signaling. Together, these data provide first sex-specific in vivo characterization of functional properties of microglia along the lifespan and identify caloric restriction as a potent, cost-effective, and clinically relevant tool for rejuvenation of microglia.
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Envejecimiento/metabolismo , Encéfalo/diagnóstico por imagen , Encéfalo/metabolismo , Restricción Calórica , Microglía/metabolismo , Animales , Calcio/metabolismo , Movimiento Celular , Femenino , Microscopía Intravital , Masculino , Ratones , Ratones Endogámicos C57BL , Microscopía Confocal , Fenotipo , Rejuvenecimiento , Factores Sexuales , Transducción de SeñalRESUMEN
Peripheral inflammation is known to trigger a mirror inflammatory response in the brain, involving brain's innate immune cells - microglia. However, the functional phenotypes, which these cells adopt in the course of peripheral inflammation, remain obscure. In vivo two-photon imaging of microglial Ca2+ signaling as well as process motility reveals two distinct functional states of cortical microglia during a lipopolysaccharide-induced peripheral inflammation: an early "sensor state" characterized by dramatically increased intracellular Ca2+ signaling but ramified morphology and a later "effector state" characterized by slow normalization of intracellular Ca2+ signaling but hypertrophic morphology, substantial IL-1ß production in a subset of cells as well as increased velocity of directed process extension and loss of coordination between individual processes. Thus, lipopolysaccharide-induced microglial Ca2+ signaling might represent the central element connecting receptive and executive functions of microglia.
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Inflamación , Microglía , Encéfalo , Humanos , Lipopolisacáridos , Transducción de SeñalRESUMEN
Neuronal hyperactivity is the emerging functional hallmark of Alzheimer's disease (AD) in both humans and different mouse models, mediating an impairment of memory and cognition. The mechanisms underlying neuronal hyperactivity remain, however, elusive. In vivo Ca2+ imaging of somatic, dendritic, and axonal activity patterns of cortical neurons revealed that both healthy aging and AD-related mutations augment neuronal hyperactivity. The AD-related enhancement occurred even without amyloid deposition and neuroinflammation, mainly due to presenilin-mediated dysfunction of intracellular Ca2+ stores in presynaptic boutons, likely causing more frequent activation of synaptic NMDA receptors. In mutant but not wild-type mice, store emptying reduced both the frequency and amplitude of presynaptic Ca2+ transients and, most importantly, normalized neuronal network activity. Postsynaptically, the store dysfunction was minor and largely restricted to hyperactive cells. These findings identify presynaptic Ca2+ stores as a key element controlling AD-related neuronal hyperactivity and as a target for disease-modifying treatments.