RESUMEN
Astrocyte diversity is greatly influenced by local environmental modulation. Here we report that the majority of astrocytes across the mouse brain possess a singular primary cilium localized to the cell soma. Comparative single-cell transcriptomics reveals that primary cilia mediate canonical SHH signaling to modulate astrocyte subtype-specific core features in synaptic regulation, intracellular transport, energy and metabolism. Independent of canonical SHH signaling, primary cilia are important regulators of astrocyte morphology and intracellular signaling balance. Dendritic spine analysis and transcriptomics reveal that perturbation of astrocytic cilia leads to disruption of neuronal development and global intercellular connectomes in the brain. Mice with primary ciliary-deficient astrocytes show behavioral deficits in sensorimotor function, sociability, learning and memory. Our results uncover a critical role for primary cilia in transmitting local cues that drive the region-specific diversification of astrocytes within the developing brain.
Asunto(s)
Astrocitos , Cilios , Proteínas Hedgehog , Transducción de Señal , Animales , Cilios/metabolismo , Cilios/fisiología , Astrocitos/metabolismo , Ratones , Transducción de Señal/fisiología , Proteínas Hedgehog/metabolismo , Proteínas Hedgehog/genética , Encéfalo/metabolismo , Encéfalo/crecimiento & desarrollo , Neurogénesis/fisiología , Ratones Endogámicos C57BL , MasculinoRESUMEN
OBJECTIVES: This systematic review and meta-analysis evaluated the diagnostic accuracy of CT and MRI for differentiating atypical lipomatous tumors and malignant liposarcomas from benign lipomatous lesions. METHODS: MEDLINE, EMBASE, Scopus, the Cochrane Library, and the gray literature from inception to January 2022 were systematically evaluated. Original studies with > 5 patients evaluating the accuracy of CT and/or MRI for detecting liposarcomas with a histopathological reference standard were included. Meta-analysis was performed using a bivariate mixed-effects regression model. Risk of bias was evaluated using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). This study is registered on PROSPERO, number CRD42022306479. RESULTS: Twenty-six studies with a total of 2613 patients were included. Mean/median reported patient ages ranged between 50 and 63 years. The summary sensitivity and specificity of radiologist gestalt for detecting liposarcomas was 85% (79-90% 95% CI) and 63% (52-72%), respectively. Deep depth to fascia, thickened septations, enhancing components, and lesion size (≥ 10 cm) all demonstrated sensitivities ≥ 85%. Other imaging characteristics including heterogenous/amorphous signal intensity, irregular tumor margin, and nodules present demonstrated lower sensitivities ranging from 43 to 65%. Inter-reader reliability for radiologist gestalt within studies ranged from fair to substantial (k = 0.23-0.7). Risk of bias was predominantly mixed for patient selection, low for index test and reference standard, and unclear for flow and timing. CONCLUSION: Higher sensitivities for detecting liposarcomas were achieved with radiologist gestalt, deep depth to fascia, thickened septations, enhancing components, and large size. Combined clinical and imaging scoring and/or radiomics both show promise for optimal performance, though require further analysis with prospective study designs. CLINICAL RELEVANCE: This pooled analysis evaluates the accuracy of CT and MRI for detecting atypical lipomatous tumors and malignant liposarcomas. Radiologist gestalt, deep depth to fascia, thickened septations, enhancing components, and large size demonstrate the highest overall sensitivities. KEY POINTS: ⢠The summary sensitivity and specificity of radiologist gestalt for detecting liposarcomas was 85% (79-90% 95% CI) and 63% (52-72%), respectively. ⢠Radiologist gestalt, deep depth to fascia, thickened septations, enhancing components, and large tumor size (≥ 10 cm) showed the highest sensitivities for detecting atypical lipomatous tumors/well-differentiated liposarcomas and malignant liposarcomas. ⢠A combined clinical and imaging scoring system and/or radiomics is likely to provide the best overall diagnostic accuracy, although currently proposed scoring systems and radiomic feature analysis require further study with prospective study designs.
Asunto(s)
Lipoma , Liposarcoma , Humanos , Persona de Mediana Edad , Reproducibilidad de los Resultados , Estudios Prospectivos , Imagen por Resonancia Magnética , Liposarcoma/diagnóstico por imagen , Liposarcoma/patología , Lipoma/diagnóstico por imagen , Lipoma/patología , Tomografía Computarizada por Rayos X , Sensibilidad y EspecificidadRESUMEN
BACKGROUND: Differentiating atypical lipomatous tumors (ALTs) and well-differentiated liposarcomas (WDLs) from benign lipomatous lesions is important for guiding clinical management, though conventional visual analysis of these lesions is challenging due to overlap of imaging features. Radiomics-based approaches may serve as a promising alternative and/or supplementary diagnostic approach to conventional imaging. PURPOSE: The purpose of this study is to review the practice of radiomics-based imaging and systematically evaluate the literature available for studies evaluating radiomics applied to differentiating ALTs/WDLs from benign lipomas. REVIEW: A background review of the radiomic workflow is provided, outlining the steps of image acquisition, segmentation, feature extraction, and model development. Subsequently, a systematic review of MEDLINE, EMBASE, Scopus, the Cochrane Library, and the grey literature was performed from inception to June 2022 to identify size studies using radiomics for differentiating ALTs/WDLs from benign lipomas. Radiomic models were shown to outperform conventional analysis in all but one model with a sensitivity ranging from 68 to 100% and a specificity ranging from 84 to 100%. However, current approaches rely on user input and no studies used a fully automated method for segmentation, contributing to interobserver variability and decreasing time efficiency. CONCLUSION: Radiomic models may show improved performance for differentiating ALTs/WDLs from benign lipomas compared to conventional analysis. However, considerable variability between radiomic approaches exists and future studies evaluating a standardized radiomic model with a multi-institutional study design and preferably fully automated segmentation software are needed before clinical application can be more broadly considered.
Asunto(s)
Lipoma , Liposarcoma , Humanos , Liposarcoma/patología , Lipoma/diagnóstico por imagenRESUMEN
L-Lactate, traditionally considered a metabolic waste product, is increasingly recognized as an important intercellular energy currency in mammals. To enable investigations of the emerging roles of intercellular shuttling of L-lactate, we now report an intensiometric green fluorescent genetically encoded biosensor for extracellular L-lactate. This biosensor, designated eLACCO1.1, enables cellular resolution imaging of extracellular L-lactate in cultured mammalian cells and brain tissue.
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Proteínas Bacterianas/metabolismo , Técnicas Biosensibles/métodos , Proteínas Fluorescentes Verdes/metabolismo , Ácido Láctico/análisis , Proteínas Periplasmáticas/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , Proteínas Bacterianas/genética , Sitios de Unión/genética , Línea Celular Tumoral , Cristalografía por Rayos X , Fluorescencia , Proteínas Fluorescentes Verdes/química , Proteínas Fluorescentes Verdes/genética , Células HEK293 , Células HeLa , Humanos , Ácido Láctico/metabolismo , Microscopía Fluorescente , Proteínas Periplasmáticas/genética , Unión Proteica , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Reproducibilidad de los ResultadosRESUMEN
Very-low-frequency oscillations in microvascular diameter cause fluctuations in oxygen delivery that are important for fueling the brain and for functional imaging. However, little is known about how the brain regulates ongoing oscillations in cerebral blood flow. In mouse and rat cortical brain slice arterioles, we find that selectively enhancing tone is sufficient to recruit a TRPV4-mediated Ca2+ elevation in adjacent astrocyte endfeet. This endfoot Ca2+ signal triggers COX-1-mediated "feedback vasodilators" that limit the extent of evoked vasoconstriction, as well as constrain fictive vasomotion in slices. Astrocyte-Ptgs1 knockdown in vivo increases the power of arteriole oscillations across a broad range of very low frequencies (0.01-0.3 Hz), including ultra-slow vasomotion (â¼0.1 Hz). Conversely, clamping astrocyte Ca2+in vivo reduces the power of vasomotion. These data demonstrate bidirectional communication between arterioles and astrocyte endfeet to regulate oscillatory microvasculature activity.
Asunto(s)
Arteriolas/fisiología , Astrocitos/fisiología , Ciclooxigenasa 1/metabolismo , Retroalimentación Fisiológica , Estrés Mecánico , Canales Catiónicos TRPV/metabolismo , Animales , Calcio/metabolismo , Femenino , Masculino , Ratones Endogámicos C57BL , Ratas Sprague-Dawley , Vasoconstricción , VasodilataciónRESUMEN
Whole brain irradiation (WBI) therapy is an important treatment for brain metastases and potential microscopic malignancies. WBI promotes progressive cognitive dysfunction in over half of surviving patients, yet, the underlying mechanisms remain obscure. Astrocytes play critical roles in the regulation of neuronal activity, brain metabolism, and cerebral blood flow, and while neurons are considered radioresistant, astrocytes are sensitive to γ-irradiation. Hallmarks of astrocyte function are the ability to generate stimulus-induced intercellular Ca2+ signals and to move metabolic substrates through the connected astrocyte network. We tested the hypothesis that WBI-induced cognitive impairment associates with persistent impairment of astrocytic Ca2+ signaling and/or gap junctional coupling. Mice were subjected to a clinically relevant protocol of fractionated WBI, and 12 to 15 months after irradiation, we confirmed persistent cognitive impairment compared to controls. To test the integrity of astrocyte-to-astrocyte gap junctional coupling postWBI, astrocytes were loaded with Alexa-488-hydrazide by patch-based dye infusion, and the increase of fluorescence signal in neighboring astrocyte cell bodies was assessed with 2-photon microscopy in acute slices of the sensory-motor cortex. We found that WBI did not affect astrocyte-to-astrocyte gap junctional coupling. Astrocytic Ca2+ responses induced by bath administration of phenylephrine (detected with Rhod-2/AM) were also unaltered by WBI. However, an electrical stimulation protocol used in long-term potentiation (theta burst), revealed attenuated astrocyte Ca2+ responses in the astrocyte arbor and soma in WBI. Our data show that WBI causes a long-lasting decrement in synaptic-evoked astrocyte Ca2+ signals 12-15 months postirradiation, which may be an important contributor to cognitive decline seen after WBI.