Microglia survey brain parenchyma, responding to injury and infections. Microglia also respond to systemic disease, but the role of blood-brain barrier (BBB) integrity in this process remains ...unclear. Using simultaneous in vivo imaging, we demonstrated that systemic inflammation induces CCR5-dependent migration of brain resident microglia to the cerebral vasculature. Vessel-associated microglia initially maintain BBB integrity via expression of the tight-junction protein Claudin-5 and make physical contact with endothelial cells. During sustained inflammation, microglia phagocytose astrocytic end-feet and impair BBB function. Our results show microglia play a dual role in maintaining BBB integrity with implications for elucidating how systemic immune-activation impacts neural functions.
Recent advances in microscopy techniques, especially in electron microscopy, are transforming biomedical studies by acquiring large quantities of high-precision 3D cell image stacks. To examine cell ...morphology and connectivity in organs such as the brain, scientists need to conduct cell segmentation, which extracts individual cell regions of different shapes and sizes from a 3D image. This is challenging due to the indistinct images often encountered in real biomedical research: in many cases, automatic segmentation methods inevitably contain numerous mistakes in the segmentation results, even when using advanced deep learning methods. To analyze 3D cell images effectively, a semi-automated software solution is needed that combines powerful deep learning techniques with the ability to perform post-processing, generate accurate segmentations, and incorporate manual corrections. To address this gap, we developed Seg2Link, which takes deep learning predictions as inputs and use watershed 2D + cross-slice linking to generate more accurate automatic segmentations than previous methods. Additionally, it provides various manual correction tools essential for correcting mistakes in 3D segmentation results. Moreover, our software has been optimized for efficiently processing large 3D images in diverse organisms. Thus, Seg2Link offers an practical solution for scientists to study cell morphology and connectivity in 3D image stacks.
We previously generated an ischemic stroke in a zebrafish model using N2 gas perfusion; however, this model was an unsuitable drug screening system due to low throughput. In this study, we examined a ...zebrafish ischemic stroke model using an oxygen absorber to assess drug effects. Hypoxic exposure more than 2 h using the oxygen absorber significantly induced cell death in the brain and damage to the neuronal cells. To confirm the utility of the ischemic model induced by the oxygen absorber, we treated zebrafish with neuroprotective agents. MK-801, an N-methyl-d-aspartate (NMDA) receptor antagonist, significantly suppressed cell death in the brain, and edaravone, a free radical scavenger, significantly reduced the number of dead cells. These results suggest that the activation of NMDA receptors and the production of reactive oxygen species induce neuronal cell damage in accordance with previous mammalian reports. We demonstrate the suitability of an ischemic stroke model in zebrafish larvae using the oxygen absorber, enabling a high throughput drug screening.
Oligodendrocyte precursor cells (OPC) arise from restricted regions of the central nervous system (CNS) and differentiate into myelin-forming cells after migration, but their ultrastructural ...characteristics have not been fully elucidated. This study examined the three-dimensional ultrastructure of OPCs in comparison with other glial cells in the early postnatal optic nerve by serial block-face scanning electron microscopy. We examined 70 putative OPCs (pOPC) that were distinct from other glial cells according to established morphological criteria. The pOPCs were unipolar in shape with relatively few processes, and their Golgi apparatus were localized in the perinuclear region with a single cisterna. Astrocytes abundant in the optic nerve were distinct from pOPCs and had a greater number of processes and more complicated Golgi apparatus morphology. All pOPCs and astrocytes contained a pair of centrioles (basal bodies). Among them, 45% of pOPCs extended a short cilium, and 20% of pOPCs had centrioles accompanied by vesicles, whereas all astrocytes with basal bodies had cilia with invaginated ciliary pockets. These results suggest that the fine structures of pOPCs during the developing and immature stages may account for their distinct behavior. Additionally, the vesicular transport of the centrioles, along with a short cilium length, suggests active ciliogenesis in pOPCs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
When a train repeatedly runs on a track, track irregularities, which are distortions of the track, gradually increase with repetition of wheel load. Tracks are normally inspected periodically so that ...maintenance can be carried out when a large track irregularities are detected. However, in rare cases, the magnitude of a track irregularity may rapidly increase locally. To ensure the safety of train operations, preventive maintenance is required to detect the signs of such rapid increases in the magnitude of irregularities and to perform maintenance before large irregularities occur. In this study, to identify in advance locations where large track irregularities are likely to occur, we developed a mathematical model that applies cluster analysis to historical data for track irregularities and maintenance records.
New neurons, continuously added in the adult olfactory bulb (OB) and hippocampus, are involved in information processing in neural circuits. Here, we show that synaptic pruning of adult-born neurons ...by microglia depends on phosphatidylserine (PS), whose exposure on dendritic spines is inversely correlated with their input activity. To study the role of PS in spine pruning by microglia in vivo, we developed an inducible transgenic mouse line, in which the exposed PS is masked by a dominant-negative form of milk fat globule-EGF-factor 8 (MFG-E8), MFG-E8D89E. In this transgenic mouse, the spine pruning of adult-born neurons by microglia is impaired in the OB and hippocampus. Furthermore, the electrophysiological properties of these adult-born neurons are altered in MFG-E8D89E mice. These data suggest that PS is involved in the microglial spine pruning and the functional maturation of adult-born neurons. The MFG-E8D89E-based genetic approach shown in this study has broad applications for understanding the biology of PS-mediated phagocytosis in vivo.
BACKGROUND
Transfusion‐transmitted bacterial infections (TTBIs) often have serious consequences for patients. The Japanese Red Cross (JRC) has not implemented culture screening for platelet ...concentrate (PC), but it has maintained a shelf life of 85 hours for PC.
STUDY DESIGN AND METHODS
The JRC collected reports of suspected TTBI and investigated causal relationships using PC samples and patient blood samples. PCs showing apparent abnormalities were retrieved and cultured and analyzed for bacterial growth.
RESULTS
The JRC analyzed 86 samples available from 135 transfused PCs with suspected TTBIs that were collected over the past 12 years; 17 (19.8%) were culture‐positive. One, 6, and 10 TTBIs developed in patients on Days 1, 2, and 3 after PC collection, respectively. Assuming that PC is transfused on the day of issue, the TTBI risk was fourfold higher on Day 3 than on Day 2, after adjusting the TTBI incidence for the number of PCs issued per day. Compared with the model of issuing all PCs on Day 3, issuing PCs with the current distribution of storage time could have decreased the TTBI incidence by 56%. During the past 8 years, the JRC retrieved 960 PC units because of apparent abnormalities, 2.8% of which were culture‐positive.
CONCLUSION
The short shelf life of PC is associated with a low incidence of reported TTBIs, more than half of which occurred on Day 3 relative to earlier time points. Visual inspection of PC before transfusion is crucial in detecting bacterially contaminated PC despite its low positive predictive value.
Oligodendrocyte precursor cells (OPC) arise from restricted regions of the central nervous system (CNS) and differentiate into myelin-forming cells after migration, but their ultrastructural ...characteristics have not been fully elucidated. This study examined the three-dimensional ultrastructure of OPCs in comparison with other glial cells in the early postnatal optic nerve by serial block-face scanning electron microscopy. We examined 70 putative OPCs (pOPC) that were distinct from other glial cells according to established morphological criteria. The pOPCs were unipolar in shape with relatively few processes, and their Golgi apparatus were localized in the perinuclear region with a single cisterna. Astrocytes abundant in the optic nerve were distinct from pOPCs and had a greater number of processes and more complicated Golgi apparatus morphology. All pOPCs and astrocytes contained a pair of centrioles (basal bodies). Among them, 45% of pOPCs extended a short cilium, and 20% of pOPCs had centrioles accompanied by vesicles, whereas all astrocytes with basal bodies had cilia with invaginated ciliary pockets. These results suggest that the fine structures of pOPCs during the developing and immature stages may account for their distinct behavior. Additionally, the vesicular transport of the centrioles, along with a short cilium length, suggests active ciliogenesis in pOPCs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Serial block-face scanning electron microscopy (SBF-SEM) was used here to study tobacco male meiosis. Three-dimensional ultrastructural analyses revealed that intercellular nuclear migration (INM) ...occurs in 90-100% of tobacco meiocytes. At the very beginning of meiosis, every meiocyte connected with neighboring cells by more than 100 channels was capable of INM. At leptotene and zygotene, the nucleus in most tobacco meiocytes approached the cell wall and formed nuclear protuberances (NPs) that crossed the cell wall through the channels and extended into the cytoplasm of a neighboring cell. The separation of NPs from the migrating nuclei and micronuclei formation were not observed. In some cases, the NPs and nuclei of neighboring cells appeared apposed to each other, and the gap between their nuclear membranes became invisible. At pachytene, NPs retracted into their own cells. After that, the INM stopped. We consider INM a normal part of tobacco meiosis, but the reason for such behavior of nuclei is unclear. The results obtained by SBF-SEM suggest that there are still many unexplored features of plant meiosis hidden by limitations of common types of microscopy and that SBF-SEM can turn over a new leaf in plant meiosis research.
Background and Purpose
Glaucoma, the leading cause of blindness, damages the retinal ganglion cells. Elevated intraocular pressure (IOP) is a high‐risk factor for glaucoma, so topical hypotensive ...drugs are usually used for treatment. Because not all patients do not respond adequately to current treatments, there is a need to identify a new molecular target to reduce IOP. Here, we have assessed the role of P2Y1 receptors in mediating elevated IOP.
Experimental Approach
P2Y1 receptor agonist was instilled into the eyes of mice, and the IOP changes were measured by a rebound‐type tonometer. Expression of P2Y1 receptors was estimated by immunohistochemistry. Ocular function was measured by a multifocal electroretinogram.
Key Results
A single dose of the P2Y1 receptor agonist transiently reduced IOP and such effects were absent in P2Y1 receptor‐deficient (P2Y1KO) mice. P2Y1 receptors were functionally expressed in the ciliary body, trabecular meshwork and Schlemm's canal. Activation of P2Y1 receptors negatively regulated aquaporin 4 (AQP4) function but up‐regulated endothelial NOS (eNOS). P2Y1KO mice showed chronic ocular hypertension regardless of age. P2Y1KO mice at 3 months old showed no damage to retinal ganglion cells, whereas 12‐month‐old mice showed a significant loss of these cells and impairment of ocular functions. Damage to retinal ganglion cells was attenuated by chronic administration of an IOP‐reducing agent.
Conclusion and Implications
Activation of P2Y1 receptors reduced IOP via dual pathways including AQP4 and eNOS. Loss of P2Y1 receptors resulted in glaucomatous optic neuropathy, suggesting that P2Y1 receptors might provide an effective target in the treatment of glaucoma.
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