Hippocampal integration and separation processes with different temporal and spatial dynamics during learning for associative memory.

The hippocampus is known to be critically involved in associative memory formation. However, the role of the hippocampus during the learning of associative memory is still controversial; while the hippocampus is considered to play a critical role in the integration of related stimuli, numerous studies also suggest a role of the hippocampus in the separation of different memory traces for rapid learning. Here, we employed an associative learning paradigm consisting of repeated learning cycles. By tracking the changes in the hippocampal representations of associated stimuli on a cycle-by-cycle basis as learning progressed, we show that both integration and separation processes occur in the hippocampus with different temporal dynamics. We found that the degree of shared representations for associated stimuli decreased significantly during the early phase of learning, whereas it increased during the later phase of learning. Remarkably, these dynamic temporal changes were observed only for stimulus pairs remembered 1 day or 4 weeks after learning, but not for forgotten pairs. Further, the integration process during learning was prominent in the anterior hippocampus, while the separation process was obvious in the posterior hippocampus. These results demonstrate temporally and spatially dynamic hippocampal processing during learning that can lead to the maintenance of associative memory.

Measurement of the thickness and refractive index of a thin film by analyzing reflected interference fringes.

We propose a novel, to the best of our knowledge, method to estimate the thickness and refractive index of a thin film by analyzing the reflectance as a function of the incidence angle. In most cases, interference fringes cannot be obtained from a film within a practical angular range unless it is much thicker than the wavelength. This problem was solved by adopting a high-index material as the medium of incidence, in which case several cycles of interference fringes were observed within a small range of incidence angles near the critical angle, allowing a fringe analysis. Consequently, the thicknesses, as well as the refractive indices of dielectric thin films, could be estimated. Our proposed method gave uncertainties of 20 nm and 0.0004 for the thickness and refractive index measurements, respectively.

Border Zone Maybe Correlated with Radiation Necrosis After Radiosurgery in Metastatic Brain Tumor.

BACKGROUND: Radiation necrosis (RN) after stereotactic radiosurgery (SRS) in brain metastases has been extensively evaluated, and RN is correlated with various risk factors. However, no study comprehensively analyzed the correlation between RN and the border zones of the brain that are vulnerable to ischemia. We hypothesized that patients with tumors in the border zone are at high risk of RN. Hence, the current study aimed to assess the correlation between border zone lesions and RN, with consideration of other predetermined factors. METHODS: This retrospective study included 117 patients with 290 lesions who underwent Gamma Knife SRS. Radiological and clinical analyses were performed to identify factors possibly correlated with RN. Notably, the lesion location was classified into 2 groups (border zone and nonborder zone) based on the blood supply. RESULTS: In total, 22 (18.8%) patients with 22 (7.5%) lesions developed RN. Univariate analysis revealed a significant correlation between RN and external border zone lesions, second course of SRS administered at the same site of the previous SRS, prescribed dose, and tumor volume. Multivariate analysis showed that border zone lesions, second course of SRS at the same site of the previous SRS, and tumor volume were significantly correlated with RN. CONCLUSIONS: Patients with tumors in the border zone are at high risk of RN. The potential risks of RN can be attributed hypothetically to hypoperfusion. Hence, the association between RN and border zone lesions seems reasonable.

The Common Effects of Sleep Deprivation on Human Long-Term Memory and Cognitive Control Processes.

Sleep deprivation is known to have adverse effects on various cognitive abilities. In particular, a lack of sleep has been reported to disrupt memory consolidation and cognitive control functions. Here, focusing on long-term memory and cognitive control processes, we review the consistency and reliability of the results of previous studies of sleep deprivation effects on behavioral performance with variations in the types of stimuli and tasks. Moreover, we examine neural response changes related to these behavioral changes induced by sleep deprivation based on human fMRI studies to determine the brain regions in which neural responses increase or decrease as a consequence of sleep deprivation. Additionally, we discuss about the possibility that light as an environmentally influential factor affects our sleep cycles and related cognitive processes.

Is Reconsolidation a General Property of Memory?

Memory reconsolidation holds great hope for memory modification approaches and clinical treatments of mental disorders associated with maladaptive memories. However, it remains controversial as to whether reconsolidation is a general property of all types of memory. Especially, discrepancies have been reported in research focusing on whether declarative memory undergoes reconsolidation, and whether old memories can be reorganized after retrieval. Here, we discuss how these inconsistent results can be reconciled and what information we need to uncover for the general use of reconsolidation.

In Vivo Gene Delivery of STC2 Promotes Axon Regeneration in Sciatic Nerves.

Neurons are vulnerable to injury, and failure to activate self-protective systems after injury leads to neuronal death. However, sensory neurons in dorsal root ganglions (DRGs) mostly survive and regenerate their axons. To understand the mechanisms of the neuronal injury response, we analyzed the injury-responsive transcriptome and found that Stc2 is immediately upregulated after axotomy. Stc2 is required for axon regeneration in vivo and in vitro, indicating that Stc2 is a neuronal factor regulating axonal injury response. The application of the secreted stanniocalcin 2 to injured DRG neurons promotes regeneration. Stc2 thus represents a potential secretory protein with a feedback function regulating regeneration. Finally, the in vivo gene delivery of STC2 increases regenerative growth after injury in peripheral nerves in mice. These results suggest that Stc2 is an injury-responsive gene required for axon regeneration and a potential target for developing therapeutic applications.

Correction: ßPix-d promotes tubulin acetylation and neurite outgrowth through a PAK/Stathmin1 signaling pathway.

[This corrects the article DOI: 10.1371/journal.pone.0230814.].

ßPix-d promotes tubulin acetylation and neurite outgrowth through a PAK/Stathmin1 signaling pathway.

Microtubules are a major cytoskeletal component of neurites, and the regulation of microtubule stability is essential for neurite morphogenesis. ßPix (ARHGEF7) is a guanine nucleotide exchange factor for the small GTPases Rac1 and Cdc42, which modulate the organization of actin filaments and microtubules. ßPix is expressed as alternatively spliced variants, including the ubiquitous isoform ßPix-a and the neuronal isoforms ßPix-b and ßPix-d, but the function of the neuronal isoforms remains unclear. Here, we reveal the novel role of ßPix neuronal isoforms in regulating tubulin acetylation and neurite outgrowth. At DIV4, hippocampal neurons cultured from ßPix neuronal isoform knockout (ßPix-NIKO) mice exhibit defects in neurite morphology and tubulin acetylation, a type of tubulin modification which often labels stable microtubules. Treating ßPix-NIKO neurons with paclitaxel, which stabilizes the microtubules, or reintroducing either neuronal ßPix isoform to the KO neurons overcomes the impairment in neurite morphology and tubulin acetylation, suggesting that neuronal ßPix isoforms may promote microtubule stabilization during neurite development. ßPix-NIKO neurons also exhibit lower phosphorylation levels for Stathmin1, a microtubule-destabilizing protein, at Ser16. Expressing either ßPix neuronal isoform in the ßPix-NIKO neurons restores Stathmin1 phosphorylation levels, with ßPix-d having a greater effect than ßPix-b. Furthermore, we find that the recovery of neurite length and Stathmin1 phosphorylation via ßPix-d expression requires PAK kinase activity. Taken together, our study demonstrates that ßPix-d regulates the phosphorylation of Stathmin1 in a PAK-dependent manner and that neuronal ßPix isoforms promote tubulin acetylation and neurite morphogenesis during neuronal development.

COVID-19 and Adverse Pregnancy Outcome: A Systematic Review of 104 Cases.

(1) Background: Until now, several reports about pregnant women with confirmed coronavirus disease 2019 (COVID-19) have been published. However, there are no comprehensive systematic reviews collecting all case series studies on data regarding adverse pregnancy outcomes, especially association with treatment modalities. (2) Objective: We aimed to synthesize the most up-to-date and relevant available evidence on the outcomes of pregnant women with laboratory-confirmed infection with COVID-19. (3) Methods: PubMed, Scopus, MEDLINE, Google scholar, and Embase were explored for studies and papers regarding pregnant women with COVID-19, including obstetrical, perinatal, and neonatal outcomes and complications published from 1 January 2020 to 4 May 2020. Systematic review and search of the published literature was done using the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA). (4) Results: In total, 11 case series studies comprising 104 pregnant women with COVID-19 were included in our review. Fever (58.6%) and cough (30.7%) were the most common symptoms. Other symptoms included dyspnea (14.4%), chest discomfort (3.9%), sputum production (1.0%), sore throat (2.9%), and nasal obstruction (1.0%). Fifty-two patients (50.0%) eventually demonstrated abnormal chest CT, and of those with ground glass opacity (GGO), 23 (22.1%) were bilateral and 10 (9.6%) were unilateral. The most common treatment for COVID-19 was administration of antibiotics (25.9%) followed by antivirals (17.3%). Cesarean section was the mode of delivery for half of the women (50.0%), although no information was available for 28.8% of the cases. Regarding obstetrical and neonatal outcomes, fetal distress (13.5%), pre-labor rupture of membranes (9.6%), prematurity (8.7%), fetal death (4.8%), and abortion (2.9%) were reported. There are no positive results of neonatal infection by RT-PCR. (5) Conclusions: Although we have found that pregnancy with COVID-19 has significantly higher maternal mortality ratio compared to that of pregnancy without the disease, the evidence is too weak to state that COVID-19 results in poorer maternal outcome due to multiple factors. The number of COVID-19 pregnancy outcomes was not large enough to draw a conclusion and long-term outcomes are yet to be determined as the pandemic is still unfolding. Active and intensive follow-up is needed in order to provide robust data for future studies.

Genetic determination of the role of PU.1 in macrophage gene expression.

PU.1, an Ets family transcription factor, mediates macrophage effector function in inflammation by regulating gene expression. But, the extent and nature of PU.1 function in gene expression has not been genetically determined because ablation of PU.1 gene abolishes macrophage development. Here, we epigenetically suppressed PU.1 by stably expressing PU.1 specific siRNA in macrophages, and determined the effect of PU.1 deficiency on expressions of key inflammatory genes: Toll-like receptor 4 (TLR4), cyclooxygenase-2 (COX-2), and macrophage inflammatory protein-1alpha (MIP-1alpha). PU.1-silenced cell lines expressed lower TLR4 mRNA and COX-2 protein, but higher MIP-1alpha protein, than controls. Over-expression of PU.1 suppressed lipopolysaccharide-induced MIP-1alpha production. PU.1 occupied proximal and distal cognate sites in the endogenous MIP-1alpha promoter, but dissociated only from the distal sites in response to lipopolysaccharide, suggesting a novel negative regulatory mechanism by PU.1. Together, our results defined PU.1 function in differentially regulating expressions of TLR4, COX-2, and MIP-1alpha.

A rapid and reliable chromosome analysis method for products of conception using interphase nuclei.

BACKGROUND: Karyotype determination has a central role in the genetic workup of pregnancy loss, as aneuploidy (trisomy and monosomy) and polyploidy (triploidy and tetraploidy) are the cause in at least 50% of first trimester, 25% of second trimester, and 11% of third trimester miscarriages. There are several limitations with the current approaches of obtaining a karyotype using traditional cytogenetics, fluorescence in situ hybridization with a limited number of probes, and chromosomal microarray. These include culture failure, incomplete results, lower sensitivity, and longer reporting time. METHODS: To overcome current limitations, a novel molecular assay is developed with a Standard Resolution Interphase Chromosome Profiling probe set which is a variation of the recently developed High Resolution probe set. It generates a molecular karyotype that can detect all major changes commonly associated with pregnancy loss. Initial familiarization of signal patterns from the probe set was used, followed by validation of the method using 83 samples from miscarriages in a blind study from three different laboratories. Finally, the clinical utility of the method was tested on 291 clinical samples in two commercial reference laboratory settings on two different continents. RESULTS: The new molecular approach not only identified all the chromosome changes observed by current methods, but also significantly improved abnormality detection by characterizing derivative chromosomes and finding subtle subtelomeric rearrangements, balanced and unbalanced. All Robertsonian translocations were also detected. The abnormality rate was 54% on clinical samples from commercial laboratory 1 and 63% from laboratory 2. CONCLUSION: The attributes of this method make it an ideal choice for the genetic workup of miscarriages, namely (1) near 100% successful results, (2) greater sensitivity than conventional chromosome analysis or FISH panels, (3) rapid reporting time, and (4) favorable comparisons with chromosomal microarray.

Expression of MYCN in Multipotent Sympathoadrenal Progenitors Induces Proliferation and Neural Differentiation, but Is Not Sufficient for Tumorigenesis.

Neuroblastoma is a pediatric malignancy of the sympathetic ganglia and adrenal glands, hypothesized to originate from progenitors of the developing sympathetic nervous system. Amplification of the MYCN oncogene is a genetic marker of risk in this disease. Understanding the impact of oncogene expression on sympathoadrenal progenitor development may improve our knowledge of neuroblastoma initiation and progression. We isolated sympathoadrenal progenitor cells from the postnatal murine adrenal gland by sphere culture and found them to be multipotent, generating differentiated colonies of neurons, Schwann cells, and myofibroblasts. MYCN overexpression in spheres promoted commitment to the neural lineage, evidenced by an increased frequency of neuron-containing colonies. MYCN promoted proliferation of both sympathoadrenal progenitor spheres and differentiated neurons derived from these spheres, but there was also an increase in apoptosis. The proliferation, apoptosis, and neural lineage commitment induced by MYCN are tumor-like characteristics and thereby support the hypothesis that multipotent adrenal medullary progenitor cells are cells of origin for neuroblastoma. We find, however, that MYCN overexpression is not sufficient for these cells to form tumors in nude mice, suggesting that additional transforming mutations are necessary for tumorigenesis.

ANKRD1 acts as a transcriptional repressor of MMP13 via the AP-1 site.

The transcriptional cofactor ANKRD1 is sharply induced during wound repair, and its overexpression enhances healing. We recently found that global deletion of murine Ankrd1 impairs wound contraction and enhances necrosis of ischemic wounds. A quantitative PCR array of Ankrd1(-/-) (KO) fibroblasts indicated that ANKRD1 regulates MMP genes. Yeast two-hybrid and coimmunoprecipitation analyses associated ANKRD1 with nucleolin, which represses AP-1 activation of MMP13. Ankrd1 deletion enhanced both basal and phorbol 12-myristate 13-acetate (PMA)-induced MMP13 promoter activity; conversely, Ankrd1 overexpression in control cells decreased PMA-induced MMP13 promoter activity. Ankrd1 reconstitution in KO fibroblasts decreased MMP13 mRNA, while Ankrd1 knockdown increased these levels. MMP13 mRNA and protein were elevated in intact skin and wounds of KO versus Ankrd1(fl/fl) (FLOX) mice. Electrophoretic mobility shift assay gel shift patterns suggested that additional transcription factors bind to the MMP13 AP-1 site in the absence of Ankrd1, and this concept was reinforced by chromatin immunoprecipitation analysis as greater binding of c-Jun to the AP-1 site in extracts from FLOX versus KO fibroblasts. We propose that ANKRD1, in association with factors such as nucleolin, represses MMP13 transcription. Ankrd1 deletion additionally relieved MMP10 transcriptional repression. Nuclear ANKRD1 appears to modulate extracellular matrix remodeling by MMPs.

Lipopolysaccharide-dependent interaction between PU.1 and c-Jun determines production of lipocalin-type prostaglandin D synthase and prostaglandin D2 in macrophages.

Previously, we reported that expression of lipocalin-prostaglandin D synthase (L-PGDS) is inducible in macrophages and protects from Pseudomonas pneumonia. Here, we investigated the mechanism by which L-PGDS gene expression is induced in macrophages. A promoter analysis of the murine L-PGDS promoter located a binding site of PU.1, a transcription factor essential for macrophage development and inflammatory gene expression. A chromatin immunoprecipitation assay showed that PU.1 bound to the cognate site in the endogenous L-PGDS promoter in response to LPS. Overexpression of PU.1, but not of PU.1(S148A), a mutant inert to casein kinase II (CKII) or NF-kappaB-inducing kinase (NIK), induced L-PGDS in RAW 264.7 cells. Conversely, siRNA silencing of PU.1 expression blunted productions of L-PGDS and prostaglandin D2 (PGD(2)). LPS treatment induced formation of the complex of PU.1 and cJun on the PU.1 site, but inactivation of cJun by treatment with JNK or p38 kinase inhibitor abolished the complex, and suppressed PU.1 transcriptional activity for L-PGDS gene expression. Together, these results show that PU.1, activated by CKII or NIK, cooperates with MAPK-activated cJun to maximally induce L-PGDS expression in macrophages following LPS treatment, and suggest that PU.1 participates in innate immunity through the production of L-PGDS and PGD(2).

Induction and function of lipocalin prostaglandin D synthase in host immunity.

Although mainly expressed in neuronal cells, lipocalin-type PGD synthase (L-PGDS) is detected in the macrophages infiltrated to atherosclerotic plaques. However, the regulation and significance of L-PGDS expression in macrophages are unknown. Here, we found that treatment of macrophages with bacterial endotoxin (LPS) or Pseudomonas induced L-PGDS expression. Epigenetic suppression of L-PGDS expression in macrophages blunted a majority of PGD(2) produced after LPS treatment. Chromatin immunoprecipitation assays show that L-PGDS induction was regulated positively by AP-1, but negatively by p53. L-PGDS expression was detected in whole lung and alveolar macrophages treated with LPS or Pseudomonas. L-PGDS overexpressing transgenic mice improved clearance of Pseudomonas from the lung compared with nontransgenic mice. Similarly, intratracheal instillation of PGD(2) enhanced removal of Pseudomonas from the lung in mice. In contrast, L-PGDS knockout mice were impaired in their ability to remove Pseudomonas from the lung. Together, our results identify induction of L-PGDS expression by inflammatory stimuli or bacterial infection, the regulatory mechanism of L-PGDS induction, and the protective role of L-PGDS expression in host immune response. Our study suggests a potential therapeutic usage of L-PGDS or PGD(2) against Pseudomonas pneumonia.

The F-actin-microtubule crosslinker Shot is a platform for Krasavietz-mediated translational regulation of midline axon repulsion.

Axon extension and guidance require a coordinated assembly of F-actin and microtubules as well as regulated translation. The molecular basis of how the translation of mRNAs encoding guidance proteins could be closely tied to the pace of cytoskeletal assembly is poorly understood. Previous studies have shown that the F-actin-microtubule crosslinker Short stop (Shot) is required for motor and sensory axon extension in the Drosophila embryo. Here, we provide biochemical and genetic evidence that Shot functions with a novel translation inhibitor, Krasavietz (Kra, Exba), to steer longitudinally directed CNS axons away from the midline. Kra binds directly to the C-terminus of Shot, and this interaction is required for the activity of Shot to support midline axon repulsion. shot and kra mutations lead to weak robo-like phenotypes, and synergistically affect midline avoidance of CNS axons. We also show that shot and kra dominantly enhance the frequency of midline crossovers in embryos heterozygous for slit or robo, and that in kra mutant embryos, some Robo-positive axons ectopically cross the midline that normally expresses the repellent Slit. Finally, we demonstrate that Kra also interacts with the translation initiation factor eIF2beta and inhibits translation in vitro. Together, these data suggest that Kra-mediated translational regulation plays important roles in midline axon repulsion and that Shot functions as a direct physical link between translational regulation and cytoskeleton reorganization.

Hepatitis C virus core protein suppresses NF-kappaB activation and cyclooxygenase-2 expression by direct interaction with IkappaB kinase beta.

In addition to hepatocytes, hepatitis C virus (HCV) infects immune cells, including macrophages. However, little is known concerning the impact of HCV infection on cellular functions of these immune effector cells. Lipopolysaccharide (LPS) activates IkappaB kinase (IKK) signalsome and NF-kappaB, which leads to the expression of cyclooxygenase-2 (COX-2), which catalyzes production of prostaglandins, potent effectors on inflammation and possibly hepatitis. Here, we examined whether expression of HCV core interferes with IKK signalsome activity and COX-2 expression in activated macrophages. In reporter assays, HCV core inhibited NF-kappaB activation in RAW 264.7 and MH-S murine macrophage cell lines treated with bacterial LPS. HCV core inhibited IKK signalsome and IKKbeta kinase activities induced by tumor necrosis factor alpha in HeLa cells and coexpressed IKKgamma in 293 cells, respectively. HCV core was coprecipitated with IKappaKappabeta and prevented nuclear translocation of IKKbeta. NF-kappaB activation by either LPS or overexpression of IKKbeta was sufficient to induce robust expression of COX-2, which was markedly suppressed by ectopic expression of HCV core. Together, these data indicate that HCV core suppresses IKK signalsome activity, which blunts COX-2 expression in macrophages. Additional studies are necessary to determine whether interrupted COX-2 expression by HCV core contributes to HCV pathogenesis.

Binding of sulfonylurea by AtMRP5, an Arabidopsis multidrug resistance-related protein that functions in salt tolerance.

Recently, a new member of the ABC transporter superfamily of Arabidopsis, AtMRP5, was identified and characterized. In the present work, we found that AtMRP5 can bind specifically to sulfonurea when it is expressed in HEK293 cells. We also present evidence for a new role of AtMRP5 in the salt stress response of Arabidopsis. We used reverse genetics to identify an Arabidopsis mutant (atmrp5-2) in which the AtMRP5 gene was disrupted by transferred DNA insertion. In root-bending assays using Murashige and Skoog medium supplemented with 100 mm NaCl, root growth of atmrp5-2 was substantially inhibited in contrast to the almost normal growth of wild-type seedlings. This hypersensitive response of the atmrp5-2 mutant was not observed during mannitol treatment. The root growth of the wild-type plant grown in Murashige and Skoog medium supplemented with the MRP inhibitor glibenclamide and NaCl was inhibited to a very similar extent as the root growth of atmrp5-2 grown in NaCl alone. The Na(+)-dependent reduction of root growth of the wild-type plant in the presence of glibenclamide was partially restored by diazoxide, a known K+ channel opener that reverses the inhibitory effects of sulfonylureas in animal cells. Moreover, the atmrp5-2 mutant was defective in 86Rb+ uptake. When seedlings were treated with 100 mm NaCl, atmrp5-2 seedlings accumulated less K+ and more Na+ than those of the wild type. These observations suggest that AtMRP5 is a putative sulfonylurea receptor that is involved in K+ homeostasis and, thus, also participates in the NaCl stress response.