Adaptive stimulus selection for consolidation in the hippocampus.

Associative memories guide behavioural adaptation by binding together outcome-predictive sensory stimuli1,2. However, in a feature-rich environment, only a subset of stimuli may predict a desired outcome3,4. How neural circuits enable behavioural adaptation by selectively and durably representing subsets of sensory stimuli that are pertinent to a specific outcome is not known. We investigated this feature selection process in the hippocampus during memory acquisition and subsequent consolidation. Two-photon calcium imaging of CA3 axonal projections to CA1 combined with simultaneous local field potential recordings revealed that CA3 projections that encode behaviourally informative sensory stimuli were selectively recruited during the memory replay events that underlie hippocampal memory consolidation5. These axonal projections formed sequential assemblies that conjunctively link sensory features to spatial location and thus reward proximity. By contrast, axons encoding uninformative, peripatetic sensory cues were notably suppressed during memory replay. Thus, while the hippocampus comprehensively encodes the real-time sensory environment, it implements a flexible filtering mechanism to maximize the utility of memories destined for long-term storage. We propose that utility-dependent recruitment of sensory experience during memory consolidation is a general coding principle for associative learning.

Anatomy education for medical students in a virtual reality workspace: A pilot study.

The COVID-19 pandemic has posed a challenge for many medical schools, as they have had to adjust their curricula into an online format. This was particularly problematic for anatomy courses as in person dissections have historically been preferred for providing students with a three-dimensional learning environment. In this study, we aim to share our experience with conducting anatomy lectures for medical student using a virtual reality (VR) workspace. Additionally, we discuss the advantages of using VR and expand on how it may be used to improve students' understanding of anatomy in comparison to various other online lecture formats. To do this, we utilized a post-lecture survey to gain feedback from the medical students that participated in a VR anatomy workspace. We found that many of our participants expressed that having access to their course material from anywhere and anytime via a virtual space, and being able to manipulate anatomical structures by moving and modifying them provided the student with a strong advantage. Although there are still limitations, we hope that our experience will assist other anatomy teachers with improving their lecture methods, especially during the pandemic.

A new option for education during surgical procedures and related clinical anatomy in a virtual reality workspace.

The COVID-19 pandemic and mandatory social distancing has brought challenges to anatomy educators who generally need in-person classes. The purpose of this study is to share the experience of a distant online lecture on a surgical procedure and related anatomy in a three-dimensional (3D) virtual reality (VR) workspace and to compare it with reported teaching methods, that is, an in-person class and a Zoom online class. The lecture was delivered by three authors of this article in a VR workspace that enables people to meet through VR. The lectures were about combinations of dental surgical procedures and related clinical anatomy. Physically, the attendees could have been located anywhere in the world, so lecturers joined from the United States and the attendees were all from Japan. VR environment and its flexibility enabled attendees to join the lecture actively, helping them to gain understanding of the surgical procedure and anatomy more efficiently. The use of VR technology with a live communication tool demonstrated in this study has several advantages over previous education methods, although there are still technical issues or disadvantages that need to be addressed. Development of the technology and app/software is required so that more data can be processed at higher speed. Use of VR technology with a live communication tool could be an alternative teaching method. Its overall advantages are a closer look at the slides/monitor and concurrent observation of the multiple assets in various directions by multiple attendees. These advantages cannot be achieved by any other teaching method without VR assets with the workspace provided by Spatial. Even during the mandatory social distancing due to the COVID-19 pandemic, this could enable us to foster 3D understanding of surgery and related anatomy. Further study is now needed to evaluate the effectiveness of this newly proposed teaching method by comparing it with traditional in-person and online classes with a live communication tool.

Easy three-dimensional scanning technology for anatomy education using a free cellphone app.

The COVID-19 pandemic has brought difficult times to anatomy educators and medical/dental students. Under normal circumstances, gross anatomy classes give students opportunities to touch and observe human bones and cadaveric tissues, thus enhancing their understanding; such morphology is difficult to learn from textbooks alone. As many studies have shown, three-dimensional (3D) technologies used in online lectures can serve as alternatives to real specimens for providing knowledge of anatomy. However, such technologies are often expensive. The goal of this study was to create 3D anatomy models for online lectures using a free cellphone app. Free application software (Qlone) was used to create 3D anatomical models. The extracranium and intracranium of adult skull, fetal skull, mandible, temporal bone, second cervical vertebra, and ilium were all scanned and exported to the computer in 3D format. A total of 53 anatomical structures were evaluated by nine observers. Although the 53 structures used in this study did not include all the structures that students need to learn, visibility was good/acceptable for most of the 53. The free and simple 3D scanning app used in this study could enable anatomy educators to provide better content to students during online lectures.

Anatomical basis for simultaneous block of greater and third occipital nerves, with an ultrasound-guided technique.

PURPOSE: In some headache disorders, for which the greater occipital nerve block is partly effective, the third occipital nerve is also suggested to be involved. We aimed to establish a simple technique for simultaneously blocking the greater and third occipital nerves. METHODS: We performed a detailed examination of dorsal neck anatomy in 33 formalin-fixed cadavers, and deduced two candidate target points for blocking both the greater and third occipital nerves. These target points were tested on three Thiel-fixed cadavers. We performed ultrasound-guided dye injections into these points, examined the results by dissection, and selected the most suitable injection point. Finally, this target point was tested in three healthy volunteers. We injected 4 ml of local anesthetic and 1 ml of radiopaque material at the selected point, guided with a standard ultrasound system. Then, the pattern of local anesthetic distribution was imaged with computed tomography. RESULTS: We deduced that the most suitable injection point was the medial head of the semispinalis capitis muscle at the C1 level of the cervical vertebra. Both nerves entered this muscle, in close proximity, with little individual variation. In healthy volunteers, an anesthetic injected was confined to the muscle and induced anesthesia in the skin areas innervated by both nerves. CONCLUSIONS: The medial head of the semispinalis capitis muscle is a suitable landmark for blocking the greater and third occipital nerves simultaneously, by which occipital nerve involvement in various headache disorders may be rapidly examined and treated.

Lack of interleukin-6 in the tumor microenvironment augments type-1 immunity and increases the efficacy of cancer immunotherapy.

Conquering immunosuppression in tumor microenvironments is crucial for effective cancer immunotherapy. It is well known that interleukin (IL)-6, a pleiotropic cytokine, is produced in the tumor-bearing state. In the present study, we investigated the precise effects of IL-6 on antitumor immunity and the subsequent tumorigenesis in tumor-bearing hosts. CT26 cells, a murine colon cancer cell line, were intradermally injected into wild-type and IL-6-deficient mice. As a result, we found that tumor growth was decreased significantly in IL-6-deficient mice compared with wild-type mice and the reduction was abrogated by depletion of CD8+ T cells. We further evaluated the immune status of tumor microenvironments and confirmed that mature dendritic cells, helper T cells and cytotoxic T cells were highly accumulated in tumor sites under the IL-6-deficient condition. In addition, higher numbers of interferon (IFN)-γ-producing T cells were present in the tumor tissues of IL-6-deficient mice compared with wild-type mice. Surface expression levels of programmed death-ligand 1 (PD-L1) and MHC class I on CT26 cells were enhanced under the IL-6-deficient condition in vivo and by IFN-γ stimulation in vitro. Finally, we confirmed that in vivo injection of an anti-PD-L1 antibody or a Toll-like receptor 3 ligand, polyinosinic-polycytidylic acid, effectively inhibited tumorigenesis under the IL-6-deficient condition. Based on these findings, we speculate that a lack of IL-6 produced in tumor-bearing host augments induction of antitumor effector T cells and inhibits tumorigenesis in vivo, suggesting that IL-6 signaling may be a promising target for the development of effective cancer immunotherapies.

The key role of IL-6-arginase cascade for inducing dendritic cell-dependent CD4(+) T cell dysfunction in tumor-bearing mice.

Evaluation of immune dysfunction during the tumor-bearing state is a critical issue in combating cancer. In this study, we initially found that IL-6, one of the cachectic factors, suppressed CD4(+) T cell-mediated immunity through downregulation of MHC class II by enhanced arginase activity of dendritic cells (DC) in tumor-bearing mice. We demonstrated that administration of Ab against IL-6R (anti-IL-6R mAb) greatly enhanced T cell responses and inhibited the growth of tumor in vivo. We also found that IL-6 upregulated the expression of arginase-1 and arginase activity of DC in vitro. Tumor-infiltrating CD11c(+) DC exhibited upregulated mRNA expression of arginase-1 but reduced expression of MHC class II in parallel with the increase in serum IL-6 levels at the late stage in tumor-bearing hosts. However, the administration of anti-IL-6R mAb into tumor-bearing mice inhibited both the downmodulation of MHC class II and the upregulation of arginase-1 mRNA levels in DC. Furthermore, we noted that N(ω)-hydroxy-L-arginine or L-arginine, an arginase-1 inhibitor, blocked the reduction in MHC class II levels on CD11c(+) DC during the tumor-bearing state. Finally, we demonstrated that the administration of N(ω)-hydroxy-L-arginine at the peritumor site significantly enhanced CD4(+) T cell responses and inhibited tumor growth. Thus, IL-6-mediated arginase activation and the subsequent reduction in MHC class II expression on DC appeared to be critical mechanisms for inducing dysfunction of the immune system in the tumor-bearing state. Blockade of the IL-6-arginase cascade is a promising tool to overcome the dysfunction of antitumor immunity in tumor-bearing hosts.

[Combined Use of a Videolaryngoscope and a Transilluminating Device for Intubation with Two Difficult Airways].

Videolaryngoscope is useful in patients with difficult airways, but it may not be in some patients. We report the use of a lighted stylet to facilitate tracheal intubation in 2 patients in whom laryngoscopy with a videolaryngoscope was difficult. Case 1: A 52-year-old female with loose teeth and lockjaw presented for a scoliosis surgery under general anesthesia. Laryngoscopy using a blade 3 of a Glide-Scope® (Laerdal Medical Corporation, New York, NY, USA) videolaryngoscope (GVL) showed a Cormack-Lehanne grade 3 view. Bag mask ventilation was easily achieved. By using the Trachilight™ (Saturn Biomedical System Burnaby, BC, Canada) with the GVL, we could intubate the trachea succesfully. Case 2: A 16-year-old male with a history of difficult tracheal intubation due to a limited cervical spine movement presented for an external fixation of a femur under general anesthesia. After induction of anaesthesia, bag mask ventilation was easily achieved but the GVL laryngoscopy did not provide a good view of the glottis (Cormack-Lehanne grade 3). Combined use of the Trachilight™ with the GVL, facilitated tracheal intubation. The Trachilight™ is a recognized aid to facilitate trachal intubation but the device is now commercially not available. Neverthless, we believe that a lighted stylet is potentially useful for tracheal intubation when the view of the glottis with a videolaryngoscopy is not ideal.

[Anesthesia for ten patients with Prader-Willi syndrome].

Previous reports indicate that Prader-Willi syndrome may present various problems during anesthesia and the perioperative period. We retrospectively investigated anesthesia records of 10 patients (2 adults and 8 children) who were diagnosed to have Prader-Willi syndrome, and who had an operation under anesthesia. Three patients had small mouths, small jaws or both. Decreased musle mass was observed in 2 patients. Two patients were morbidly obese (BMI 33, and 51). General anesthesia was used in 9 patients. Spinal anesthesia under fluoroscopy was performed in the remaining one patient who was morbidly obese (BMI 51). Among 9 patients who received general anesthesia, mask ventilation was difficult in one patient, but insertion of an oral airway relieved the problem. Difficult tracheal intubation occurred in one patient. No other major problems occurred. We conclude that the incidence of problems during anesthesia and postoperative period in patients with Prader-Willi syndrome would be less than previously considered.

Inhibitory plasticity supports replay generalization in the hippocampus.

Memory consolidation assimilates recent experiences into long-term memory. This process requires the replay of learned sequences, although the content of these sequences remains controversial. Recent work has shown that the statistics of replay deviate from those of experience: stimuli that are experientially salient may be either recruited or suppressed from sharp-wave ripples. In this study, we found that this phenomenon can be explained parsimoniously and biologically plausibly by a Hebbian spike-time-dependent plasticity rule at inhibitory synapses. Using models at three levels of abstraction-leaky integrate-and-fire, biophysically detailed and abstract binary-we show that this rule enables efficient generalization, and we make specific predictions about the consequences of intact and perturbed inhibitory dynamics for network dynamics and cognition. Finally, we use optogenetics to artificially implant non-generalizable representations into the network in awake behaving mice, and we find that these representations also accumulate inhibition during sharp-wave ripples, experimentally validating a major prediction of our model. Our work outlines a potential direct link between the synaptic and cognitive levels of memory consolidation, with implications for both normal learning and neurological disease.

Trisomy 12 compromises the mesendodermal differentiation propensity of human pluripotent stem cells.

Trisomy 12 is one of the most frequent chromosomal abnormalities in cultured human pluripotent stem cells (hPSCs). Although potential oncogenic properties and augmented cell cycle caused by trisomy 12 have been reported, the consequences of trisomy 12 in terms of cell differentiation, which is the basis for regenerative medicine, drug development, and developmental biology studies, have not yet been investigated. Here, we report that trisomy 12 compromises the mesendodermal differentiation of hPSCs. We identified sublines of hPSCs carrying trisomy 12 after their prolonged culture. Transcriptome analysis revealed that these hPSC sublines carried abnormal gene expression patterns in specific signaling pathways in addition to cancer-related cell cycle pathways. These hPSC sublines showed a lower propensity for mesendodermal differentiation in embryoid bodies cultured in a serum-free medium. BMP4-induced exit from the self-renewal state was impaired in the trisomy 12 hPSC sublines, with less upregulation of key transcription factor gene expression. As a consequence, the differentiation efficiency of hematopoietic and hepatic lineages was also impaired in the trisomy 12 hPSC sublines. We reveal that trisomy 12 disrupts the genome-wide expression patterns that are required for proper mesendodermal differentiation.

Anti-IL-6 receptor mAb eliminates myeloid-derived suppressor cells and inhibits tumor growth by enhancing T-cell responses.

CD11b(+) Gr-1(+) immature myeloid cells (ImCs), which are abnormally increased in tumor-bearing mice, were classified into three different subsets according to their phenotypic and morphological characteristics: Gr-1(low) F4/80(+) macrophages (MΦ-ImCs), Gr-1(mid) stab neutrophils (Neut(stab)-ImCs), and Gr-1(high) segmented neutrophils (Neut(seg)-ImCs). In the spleen, only MΦ-ImCs but not Neut(stab)-ImCs and Neut(seg)-ImCs exhibited a significant immunosuppressive activity in MLR. In contrast, tumor-infiltrating leukocytes (TILs) contained only two ImC subsets, MΦ-ImCs and Neut(seg)-ImC, both of which exhibited stronger inhibitory activity against T cells compared with spleen-MΦ-ImCs. Thus, we concluded that tumor-infiltrating MΦ-ImCs and Neut(seg)-ImCs were fully differentiated myeloid-derived suppressor cells (MDSCs) with stronger T-cell inhibitory activity. Indeed, spleen MΦ-ImCs were converted into stronger MΦ-MDSCs by tumor-derived factor (TDF). Moreover, both spleen Neut(stab)-ImCs and Neut(seg)-ImCs differentiated into Neut(seg)-MDSCs with suppressive activity after culture with TDF. We first demonstrated that administration of anti-IL-6R mAb could downregulate the accumulation of MΦ-MDSCs and Neut(seg)-MDSCs in tumor-bearing mice. The elimination of those MDSCs caused subsequent enhancement of antitumor T-cell responses, including IFN-γ-production. The therapeutic effect of anti-IL-6R mAb was further enhanced by combination with gemcitabine (GEM). Thus, we propose that anti-IL-6R mAb could become a novel tool for the downmodulation of MDSCs to enhance antitumor T-cell responses in tumor-bearing hosts.

Antibiofilm Property and Biocompatibility of Siloxane-Based Polymer Coatings Applied to Biomaterials.

Biofilm infections sometimes occur on biomaterials inserted into the body because biomaterials can block the attack of immune cells such as macrophages, promoting biofilm formation by invading bacteria. Owing to their use in antifouling applications, including biofilm formation, siloxane-based polymer coatings are considered a promising method to prevent biofilm formation on the surface of biomaterials. In this study, we explored the antibiofilm property and biocompatibility of siloxane-based polymer coatings. Biofilm formation and cytotoxicity tests were performed using Escherichia coli and Staphylococcus epidermidis to quantify the biofilms while U937 cells were used to measure the time course of viable cell concentration and viability, respectively. In both the biofilm formation and cytotoxicity tests, stainless steel SUS316L plates and titanium plates coated with the siloxane-based polymer and sterilized in an autoclave were used as the biomaterials. The amount of biofilm formed on the polymer-coated titanium plate was substantially higher than that on a noncoated titanium plate in the case of S. epidermidis. The viable cell concentration and viability of U937 cultured on the polymer-coated titanium plate were lower than those of U937 cultured on the noncoated titanium plate. The same trend was observed between polymer-coated and noncoated SUS316L plates. These results indicate that the siloxane-based polymer coatings need additional treatment to achieve a satisfactory antibiofilm property and that they are sensitive to autoclave treatment, resulting in cytotoxicity.

Timing of the administration of suramin treatment after muscle injury.

INTRODUCTION: It has been reported that suramin treatment can improve muscle healing; however, details about optimizing the dosing requirements remain unclear. The purpose of this study was to determine the optimal timing of suramin administration and investigate the effects it had on the expression of myostatin, follistatin, and muscle vascularity after muscle injury. METHODS: Contusion injured muscles of mice were treated with suramin at 1, 2, or 3 weeks post-injury and evaluated histologically and physiologically at 1, 2, and 10 days after injection. RESULTS: Suramin treatment initiated at 2 weeks post-injury was observed to promote muscle regeneration and muscle strength, and to decrease fibrosis. Suramin reduced myostatin expression and increased follistatin expression and vascularity in injured skeletal muscle. CONCLUSIONS: Suramin's positive effect on muscle regeneration is thought to be due to its enhancement of follistatin expression which increases neoangiogenesis and inhibits myostatin's promotion of fibrosis.

E-Cannula reveals anatomical diversity in sharp-wave ripples as a driver for the recruitment of distinct hippocampal assemblies.

The hippocampus plays a critical role in spatial navigation and episodic memory. However, research on in vivo hippocampal activity dynamics mostly relies on single modalities, such as electrical recordings or optical imaging, with respectively limited spatial and temporal resolution. Here, we develop the E-Cannula, integrating fully transparent graphene microelectrodes with imaging cannula, which enables simultaneous electrical recording and two-photon calcium imaging from the exact same neural populations across an anatomically extended region of the mouse hippocampal CA1 stably across several days. The large-scale multimodal recordings show that sharp wave ripples (SWRs) exhibit spatiotemporal wave patterns along multiple axes in two-dimensional (2D) space with different spatial extents and temporal propagation modes. Notably, distinct SWR wave patterns are associated with the selective recruitment of orthogonal CA1 cell assemblies. These results demonstrate the utility of the E-Cannula as a versatile neurotechnology with the potential for future integration with other optical components.

A case of degloving injury of the whole hand reconstructed by a combination of distant flaps comprising an anterolateral thigh flap and a groin flap.

A case of degloving injury of the whole hand reconstructed by a combination of an anterolateral thigh (ALT) flap and a groin flap applied as a pedicled distant flap was reported. Despite complications of congestion of the ALT flap and superficial infection, both flaps were severed at 4 weeks after transplantation, and a useful hand was finally reconstructed. The combination of a pedicled groin flap and an ALT flap is not optimal for reconstruction of a whole-hand degloving injury but is considered to be an available procedure for covering a large skin defect without microsurgical procedures.

Fructan Improves Survival and Function of Cryopreserved Rat Islets.

Cryopreservation of pancreatic islets enables their long-term storage and subsequent transplantation; however, post-cryopreservation, islets viability, and functions are reduced to a significant extent. Islet is composed of five cells (α cell, ß cell, δ cell, ε cell, and PP cell), and blood vessels that carry the nutrition. Freezing technology of the organization has not developed a good method. This paper is studied using a fructan which has been found to effectively freeze protect a material of the cell. Islet transplantation has been established as an effective means of treating patients with type 1 diabetes. In this study, we demonstrated the effectiveness of using a fructan on the cryopreserved islets by showing valid results for diabetes. Isolated rat islets were cryopreserved using phosphate-buffered saline (PBS) supplemented with different concentrations of fructan and/or dimethyl sulfoxide (DMSO) in FBS. The survival rates of the islets were estimated at different time intervals, and insulin secretion function was tested in vitro. Furthermore, the in vivo function was tested by syngeneic transplantation into streptozotocin-induced diabetic rats, and the grafts were analyzed histologically and immunohistochemically. Fructan significantly increased islet survival; 30% fructan led to survival rates of more than 90% on day 3, which was significantly higher than those of the DMSO groups (p < 0.05). For both fructan and DMSO, the survival showed dose dependence, with the highest rates observed for 30% fructan and 10% DMSO, respectively (p < 0.05). The fructan groups showed a significantly increased insulin secretion volume in comparison to the DMSO groups (p < 0.05). Furthermore, cell clusters of pancreatic islets were well maintained in the fructan group, whereas margin collapse and vacuolation were observed in the DMSO group. Three days after transplantation of pancreatic islets preserved with 30% fructan, the blood glucose levels of diabetic rats were restored to the normal range, and removal of transplanted pancreatic islets from the kidney led to a profound increase in blood glucose levels. Together, these results show that a fructan is effective at cryopreserving rat pancreatic islets for subsequent transplantation.

Supramammillary regulation of locomotion and hippocampal activity.

Locomotor speed is a basic input used to calculate one's position, but where this signal comes from is unclear. We identified neurons in the supramammillary nucleus (SuM) of the rodent hypothalamus that were highly correlated with future locomotor speed and reliably drove locomotion when activated. Robust locomotion control was specifically identified in Tac1 (substance P)­expressing (SuMTac1+) neurons, the activation of which selectively controlled the activity of speed-modulated hippocampal neurons. By contrast, Tac1-deficient (SuMTac1−) cells weakly regulated locomotion but potently controlled the spike timing of hippocampal neurons and were sufficient to entrain local network oscillations. These findings emphasize that the SuM not only regulates basic locomotor activity but also selectively shapes hippocampal neural activity in a manner that may support spatial navigation.