Lipocalin‐2 (LCN2) has diverse functions in multiple pathophysiological conditions; however, its pathogenic role in vascular dementia (VaD) is unknown. Here, we investigated the role of LCN2 in VaD ...using rodent models of global cerebral ischemia and hypoperfusion with cognitive impairment and neuroinflammation. Mice subjected to transient bilateral common carotid artery occlusion (tBCCAo) for 50 min showed neuronal death and gliosis in the hippocampus at 7 days post‐tBCCAo. LCN2 expression was observed predominantly in the hippocampal astrocytes, whereas its receptor was mainly detected in neurons, microglia, and astrocytes. Furthermore, Lcn2‐deficient mice, compared with wild‐type animals, showed significantly weaker CA1 neuronal loss, cognitive decline, white matter damage, blood–brain barrier permeability, glial activation, and proinflammatory cytokine production in the hippocampus after tBCCAo. Lcn2 deficiency also attenuated hippocampal neuronal death and cognitive decline at 30 days after unilateral common carotid artery occlusion (UCCAo). Furthermore, intracerebroventricular (i.c.v) injection of recombinant LCN2 protein elicited CA1‐neuronal death and a cognitive deficit. Our studies using cultured glia and hippocampal neurons supported the decisive role of LCN2 in hippocampal neurotoxicity and microglial activation, and the role of the HIF‐1α–LCN2–VEGFA axis of astrocytes in vascular injury. Additionally, plasma levels of LCN2 were significantly higher in patients with VaD than in the healthy control subjects. These results indicate that hippocampal damage and cognitive impairment are mediated by LCN2 secreted from reactive astrocytes in VaD.
Main Points
Astrocyte‐derived LCN2 mediates hippocampal damage in rodent models of vascular dementia, with higher plasma levels of LCN2 protein in patients with vascular dementia, suggesting the possibility of effective glia‐based treatment for vascular dementia.
The associative network of hippocampal CA3 is thought to contribute to rapid formation of contextual memory from one-trial learning, but the network mechanisms underlying decorrelation of neuronal ...ensembles in CA3 is largely unknown. Kv1.2 expressions in rodent CA3 pyramidal cells (CA3-PCs) are polarized to distal apical dendrites, and its downregulation specifically enhances dendritic responses to perforant pathway (PP) synaptic inputs. We found that haploinsufficiency of Kv1.2 (Kcna2+/-) in CA3-PCs, but not Kv1.1 (Kcna1+/-), lowers the threshold for long-term potentiation (LTP) at PP-CA3 synapses, and that the Kcna2+/- mice are normal in discrimination of distinct contexts but impaired in discrimination of similar but slightly distinct contexts. We further examined the neuronal ensembles in CA3 and dentate gyrus (DG), which represent the two similar contexts using in situ hybridization of immediate early genes, Homer1a and Arc. The size and overlap of CA3 ensembles activated by the first visit to the similar contexts were not different between wild type and Kcna2+/- mice, but these ensemble parameters diverged over training days between genotypes, suggesting that abnormal plastic changes at PP-CA3 synapses of Kcna2+/- mice is responsible for the impaired pattern separation. Unlike CA3, DG ensembles were not different between two genotype mice. The DG ensembles were already separated on the first day, and their overlap did not further evolve. Eventually, the Kcna2+/- mice exhibited larger CA3 ensemble size and overlap upon retrieval of two contexts, compared to wild type or Kcna1+/- mice. These results suggest that sparse LTP at PP-CA3 synapse probably supervised by mossy fiber inputs is essential for gradual decorrelation of CA3 ensembles.
Quantum dot (QD) light-emitting diodes (LEDs) are ideal for large-panel displays because of their excellent efficiency, colour purity, reliability and cost-effective fabrication
. Intensive efforts ...have produced red-, green- and blue-emitting QD-LEDs with efficiencies of 20.5 per cent
, 21.0 per cent
and 19.8 per cent
, respectively, but it is still desirable to improve the operating stability of the devices and to replace their toxic cadmium composition with a more environmentally benign alternative. The performance of indium phosphide (InP)-based materials and devices has remained far behind those of their Cd-containing counterparts. Here we present a synthetic method of preparing a uniform InP core and a highly symmetrical core/shell QD with a quantum yield of approximately 100 per cent. In particular, we add hydrofluoric acid to etch out the oxidative InP core surface during the growth of the initial ZnSe shell and then we enable high-temperature ZnSe growth at 340 degrees Celsius. The engineered shell thickness suppresses energy transfer and Auger recombination in order to maintain high luminescence efficiency, and the initial surface ligand is replaced with a shorter one for better charge injection. The optimized InP/ZnSe/ZnS QD-LEDs showed a theoretical maximum external quantum efficiency of 21.4 per cent, a maximum brightness of 100,000 candelas per square metre and an extremely long lifetime of a million hours at 100 candelas per square metre, representing a performance comparable to that of state-of-the-art Cd-containing QD-LEDs. These as-prepared InP-based QD-LEDs could soon be usable in commercial displays.
Aim
To determine the tensile load capacity (TLC) and the tearing characteristics for interrupted and vertical mattress sutures with different insertion points from the wound margin, and the effect of ...the bite size when using vertical mattress sutures.
Materials and Methods
A total of 120 gingiva and lining mucosa samples obtained from pig jaws were divided into groups according to the suturing technique (interrupted and vertical mattress sutures), distance of the insertion points from the wound margin (margin, 1, 3, and 5 mm) and bite size (1, 3, and 5 mm). The TLC of the suture and the tearing characteristics were evaluated using a tensile tester device.
Results
The TLC was significantly higher for vertical mattress sutures than for interrupted sutures regardless of the distance of the insertion points from the wound margin (intergroup p < .001). This distance significantly influenced the TLC for vertical mattress sutures (p < .05) but not for interrupted sutures (p > .05). Testing the tearing characteristics revealed that no tissue tearing occurred in groups when the insertion points were more than 3 mm from the wound margin.
Conclusion
The TLC is higher for vertical mattress sutures than for interrupted sutures, and it increases when the insertion points are farther from the wound margin.
Astrocytes, which are homeostatic cells of the central nervous system (CNS), display remarkable heterogeneity in their morphology and function. Besides their physical and metabolic support to ...neurons, astrocytes modulate the blood-brain barrier, regulate CNS synaptogenesis, guide axon pathfinding, maintain brain homeostasis, affect neuronal development and plasticity, and contribute to diverse neuropathologies via secreted proteins. The identification of astrocytic proteome and secretome profiles has provided new insights into the maintenance of neuronal health and survival, the pathogenesis of brain injury, and neurodegeneration. Recent advances in proteomics research have provided an excellent catalog of astrocyte-secreted proteins. This review categorizes astrocyte-secreted proteins and discusses evidence that astrocytes play a crucial role in neuronal activity and brain function. An in-depth understanding of astrocyte-secreted proteins and their pathways is pivotal for the development of novel strategies for restoring brain homeostasis, limiting brain injury/inflammation, counteracting neurodegeneration, and obtaining functional recovery.
Aim
To determine the healing outcome following grafting with deproteinized porcine bone mineral (DPBM) with or without collagen membrane coverage in two‐wall (both buccal and lingual)‐damaged ...extraction sockets.
Materials and methods
Distal roots of three mandibular premolars in six beagle dogs were extracted, and the whole buccal and lingual bony walls were surgically removed. Three treatment protocols were then applied according to the following group allocation: no graft (None), grafting DPBM (BG), and grafting DPBM with coverage by a collagen membrane (BG + M). Two observational periods (2 and 8 weeks) were used with the split‐mouth design, and quantitative and qualitative analyses were performed by microcomputed tomography and histology.
Results
The dimensions of the alveolar ridge at both grafted sites (BG and BG + M) remained similar to those of the pristine ridge in the histologic and radiographic analyses, whereas the ungrafted sites (None) collapsed both vertically and horizontally. Both grafting protocols produced substantial bony regeneration, but the addition of a covering membrane enhanced the proportion of mineralized tissue within the augmented area, and the BG + M group also showed a significantly larger area of regenerated ridge than the None group (p < .05).
Conclusions
Bone grafting with collagen membrane can maintain the alveolar ridge dimensions with substantial bone regeneration in a two‐wall‐damaged extraction socket.
This letter presents a position sensorless control method of brushless dc (BLDC) motors considering unbalanced zero-crossing detection of back electromotive force (back EMF). The zero-crossing point ...(ZCP) of back EMF voltage is detected by comparing the dc-link voltage with the back EMF voltage. The unbalanced ZCP detection is caused by the dc-link voltage drop, dc-link offset voltage, and a motor having asymmetric back EMFs. Because the sensorless BLDC motor control is based on unbalanced ZCP detection, issues with torque ripple and current ripple may be increased. Therefore, sensorless operation with unbalanced ZCP detection may be unstable. In this study, an improved sensorless control method based on a simple compensation algorithm using ZCP signals is proposed. Using the proposed control method, balanced commutation instants can be obtained and the benefits of high-performance operation of BLDC motors can be accomplished. Through application of the proposed method, the effectiveness of the proposed method was experimentally verified.
The burgeoning demand for commercializing self‐luminescing quantum dot (QD) light‐emitting diodes (LEDs) has stimulated extensive research into environmentally friendly and efficient QD materials. ...Hydrofluoric acid (HF) additive improves photoluminescence (PL) properties of blue‐emitting ZnSeTe QDs, ultimately reaching a remarkable quantum yield (QY) of 97% with an ultranarrow peak width of 14 nm after sufficient HF addition. The improvement in optical properties of the QDs is accompanied by a morphology change of the particles, forming cubic‐shaped defect‐free ZnSeTe QDs characterized by a zinc blende (ZB) crystal structure. This treatment improves the QD‐emitting properties by facilitating facet‐specific growth, selectively exposing stabilized (100) facets, and reducing the lattice disorders. The facet‐specific growth process gives rise to defect‐free monodispersed cubic dots that exhibit remarkably narrow and homogeneous PL spectra. Meticulous time‐resolved spectroscopic studies allow an understanding of the correlation between ZnSeTe QDs’ particle shape and performance following HF addition. These investigations shed light on the intricacies of the growth mechanism and the factors influencing the PL efficiency of the resulting QDs. The findings significantly contribute to understanding the role of HF treatment in tailoring the optical properties of ZnSeTe QDs, thereby bringing it closer to the realization of highly efficient and bright QD‐LEDs for various practical applications.
The crystal structure and spectroscopic properties of blue‐emitting ZnSeTe quantum dots (QDs) are studied to elucidate the mechanism behind the facet‐specific growth and enhanced emitting properties induced by hydrofluoric acid (HF) treatment. Not only the role of HF treatment is unveiled, but also the interplay between the lattice structure, defect density, and photoluminescence properties of ZnSeTe QDs is thoroughly analyzed.
Chlorogenic acid (CGA), an ester of caffeic acid and quinic acid, is among the phenolic acid compounds which can be naturally found in green coffee extract and tea. CGA has been studied since it ...displays significant pharmacological properties. The aim of this study was to investigate the effects of CGA on cognitive function and neuroprotection including its mechanisms in the hippocampus following transient forebrain ischemia in gerbils. Memory and learning following the ischemia was investigated by eight-arm radial maze and passive avoidance tests. Neuroprotection was examined by immunohistochemistry for neuronal nuclei-specific protein and Fluoro-Jade B histofluorescence staining. For mechanisms of the neuroprotection, alterations in copper, zinc-superoxide dismutase (SOD1), SOD2 as antioxidant enzymes, dihydroethidium and 4-hydroxy-2-nonenal as indicators for oxidative stress, and anti-inflammatory cytokines (interleukin (IL)-4 and IL-13) and pro-inflammatory cytokines (tumor necrosis factor α (TNF-α) and IL-2) were examined by Western blotting and/or immunohistochemistry. As a result, pretreatment with 30 mg/kg CGA attenuated cognitive impairment and displayed a neuroprotective effect against transient forebrain ischemia (TFI). In Western blotting, the expression levels of SOD2 and IL-4 were increased due to pretreatment with CGA and, furthermore, 4-HNE production and IL-4 expressions were inhibited by CGA pretreatment. Additionally, pretreated CGA enhanced antioxidant enzymes and anti-inflammatory cytokines and, in contrast, attenuated oxidative stress and pro-inflammatory cytokine expression. Based on these results, we suggest that CGA can be a useful neuroprotective material against ischemia-reperfusion injury due to its antioxidant and anti-inflammatory efficacies.
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