Proposal of a Network System to Solve the Problem of Small Volume in Liver Transplantation; Catholic Medical Center Network.

INTRODUCTION: Liver transplantation (LT) is a complex and demanding procedure associated with significant perioperative challenges and risks. Concerns have arisen regarding LT outcomes in low-volume centers. We implemented an integrated training and surgical team network to address these concerns within the Catholic Medical Center (CMC) network. This study presents a comprehensive review of our 9-year LT experience within the CMC medical network. METHOD: A retrospective study of LT procedures conducted between January 2013 and August 2021 in 6 CMC-affiliated hospitals was performed. One center was categorized as a high-volume center, conducting over 60 cases annually, and the remaining 5 were considered small-volume centers. The primary endpoints assessed were 1-year and 5-year survival rates. RESULTS: A total of 793 LTs were performed during the study period. The high-volume center performed 411 living donor LT (LDLT) cases and 127 deceased donor LT (DDLT) cases. Also, 146 LDLT cases and 109 DDLT cases were performed in 5 small-volume centers. One-year and 5-year patient survival for LDLT recipients was 88.3% and 78.8% in the high-volume center and 85.6% and 80.6% in the low-volume center. Five-year survival was not significantly different in small-volume centers (P = .903). For DDLT recipients, 1-year and 5-year patient survival was 80.3% and 70.6% in the high-volume center and 76.1% and 67.6% in the low-volume center. In DDLT cases, 5-year survival was not significantly different in small-volume centers (P = .445). CONCLUSION: In conclusion, comparable outcomes for liver transplantation can be obtained in a small-volume center with a high level of integrated training systems and networks.

Molecular Decrowding by Tissue Expansion Allows Precise Determination of the Spatial Distribution of Synaptic Proteins at a Nanometer Scale by exTEM.

To understand how the molecular machinery of synapses works, it is essential to determine an inventory of synaptic proteins at a subsynaptic resolution. Nevertheless, synaptic proteins are difficult to localize because of the low expression levels and limited access to immunostaining epitopes. Here, we report on the exTEM (epitope-exposed by expansion-transmission electron microscopy) method that enables the imaging of synaptic proteins in situ. This method combines TEM with nanoscale resolution and expandable tissue-hydrogel hybrids for enhanced immunolabeling with better epitope accessibility via molecular decrowding, allowing successful probing of the distribution of various synapse-organizing proteins. We propose that exTEM can be employed for studying the mechanisms underlying the regulation of synaptic architecture and function by providing nanoscale molecular distribution of synaptic proteins in situ. We also envision that exTEM is widely applicable for investigating protein nanostructures located in densely packed environments by immunostaining of commercially available antibodies at nanometer resolution.

Spatial Transcriptomics: Technical Aspects of Recent Developments and Their Applications in Neuroscience and Cancer Research.

Spatial transcriptomics is a newly emerging field that enables high-throughput investigation of the spatial localization of transcripts and related analyses in various applications for biological systems. By transitioning from conventional biological studies to "in situ" biology, spatial transcriptomics can provide transcriptome-scale spatial information. Currently, the ability to simultaneously characterize gene expression profiles of cells and relevant cellular environment is a paradigm shift for biological studies. In this review, recent progress in spatial transcriptomics and its applications in neuroscience and cancer studies are highlighted. Technical aspects of existing technologies and future directions of new developments (as of March 2023), computational analysis of spatial transcriptome data, application notes in neuroscience and cancer studies, and discussions regarding future directions of spatial multi-omics and their expanding roles in biomedical applications are emphasized.

A Single Center Experience of the Prognosis After Liver Transplantation From Discarded Graft Due to Poor Graft Conditions in Prioritized Centers.

BACKGROUND: Liver transplantation (LT) has the limitation of graft shortage. Therefore, to increase the donor pool, even marginal grafts are being transplanted depending on the recipient's condition. This study was conducted to analyze the post-LT prognosis using discarded liver grafts. METHODS AND MATERIALS: From January 2010 to September 2020, deceased-donor LT was performed in 160 patients in our center. Among them, 121 patients (allocated group) were preferentially allocated to our center, and the remaining 39 patients (24.4%, discarded group) received liver grafts that were discarded by prioritized centers. RESULTS: The preoperative model for end-stage liver disease score were 27.0 ± 10.41 and 27.0 ±11.79 for each group (P = .99). There were no differences between the 2 groups in operation time (P = .06) and intraoperative packed red cell transfusion (P = .90). There were no differences between the 2 groups in early allograft dysfunction (P = .48) and hospital stay (P = .26) after deceased-donor LT. In-hospital mortality occurred in 10 patients (8.3%) in the allocated group and 4 patients (10.3%) in the discarded group. Only the length of intensive care unit stay was significantly longer in the discarded group (P = 0.04). The 5-year survival rate was 73.8% in the allocated group and 72.2% in the discarded group. CONCLUSIONS: The outcome of the discarded group is never worse than that of the allocated group. deceased-donor LT from the discarded graft can be acceptable. As a result, the number of discarded grafts can be reduced.

A forebrain neural substrate for behavioral thermoregulation.

Thermoregulatory behavior is a basic motivated behavior for body temperature homeostasis. Despite its fundamental importance, a forebrain region or defined neural population required for this process has yet to be established. Here, we show that Vgat-expressing neurons in the lateral hypothalamus (LHVgat neurons) are required for diverse thermoregulatory behaviors. The population activity of LHVgat neurons is increased during thermoregulatory behavior and bidirectionally encodes thermal punishment and reward (P&R). Although this population also regulates feeding and caloric reward, inhibition of parabrachial inputs selectively impaired thermoregulatory behaviors and encoding of thermal stimulus by LHVgat neurons. Furthermore, two-photon calcium imaging revealed a subpopulation of LHVgat neurons bidirectionally encoding thermal P&R, which is engaged during thermoregulatory behavior, but is largely distinct from caloric reward-encoding LHVgat neurons. Our data establish LHVgat neurons as a required neural substrate for behavioral thermoregulation and point to the key role of the thermal P&R-encoding LHVgat subpopulation in thermoregulatory behavior.

Lateral Septum Somatostatin Neurons are Activated by Diverse Stressors.

The lateral septum (LS) is a forebrain structure that has been implicated in a wide range of behavioral and physiological responses to stress. However, the specific populations of neurons in the LS that mediate stress responses remain incompletely understood. Here, we show that neurons in the dorsal lateral septum (LSd) that express the somatostatin gene (hereafter, LSdSst neurons) are activated by diverse stressors. Retrograde tracing from LSdSst neurons revealed that these neurons are directly innervated by neurons in the locus coeruleus (LC), the primary source of norepinephrine well-known to mediate diverse stress-related functions in the brain. Consistently, we found that norepinephrine increased excitatory synaptic transmission onto LSdSst neurons, suggesting the functional connectivity between LSdSst neurons and LC noradrenergic neurons. However, optogenetic stimulation of LSdSst neurons did not affect stress-related behaviors or autonomic functions, likely owing to the functional heterogeneity within this population. Together, our findings show that LSdSst neurons are activated by diverse stressors and suggest that norepinephrine released from the LC may modulate the activity of LSdSst neurons under stressful circumstances.

Expansion Microscopy with a Thermally Adjustable Expansion Factor Using Thermoresponsive Biospecimen-Hydrogel Hybrids.

Expansion microscopy (ExM) is a technique in which swellable hydrogel-embedded biological samples are physically expanded to effectively increase imaging resolution. Here, we develop thermoresponsive reversible ExM (T-RevExM), in which the expansion factor can be thermally adjusted in a reversible manner. In this method, samples are embedded in thermoresponsive hydrogels and partially digested to allow for reversible swelling of the sample-gel hybrid in a temperature-dependent manner. We first synthesized hydrogels exhibiting lower critical solution temperature (LCST)- and upper critical solution temperature (UCST)-phase transition properties with N-alkyl acrylamide or sulfobetaine monomers, respectively. We then formed covalent hybrids between the LCST or UCST hydrogel and biomolecules across the cultured cells and tissues. The resulting hybrid could be reversibly swelled or deswelled in a temperature-dependent manner, with LCST- and UCST-based hybrids negatively and positively responding to the increase in temperature (termed thermonegative RevExM and thermopositive RevExM, respectively). We further showed reliable imaging of both unexpanded and expanded cells and tissues and demonstrated minimal distortions from the original sample using conventional confocal microscopy. Thus, T-RevExM enables easy adjustment of the size of biological samples and therefore the effective magnification and resolution of the sample, simply by changing the sample temperature.

A neural circuit mechanism for mechanosensory feedback control of ingestion.

Mechanosensory feedback from the digestive tract to the brain is critical for limiting excessive food and water intake, but the underlying gut-brain communication pathways and mechanisms remain poorly understood1-12. Here we show that, in mice, neurons in the parabrachial nucleus that express the prodynorphin gene (hereafter, PBPdyn neurons) monitor the intake of both fluids and solids, using mechanosensory signals that arise from the upper digestive tract. Most individual PBPdyn neurons are activated by ingestion as well as the stimulation of the mouth and stomach, which indicates the representation of integrated sensory signals across distinct parts of the digestive tract. PBPdyn neurons are anatomically connected to the digestive periphery via cranial and spinal pathways; we show that, among these pathways, the vagus nerve conveys stomach-distension signals to PBPdyn neurons. Upon receipt of these signals, these neurons produce aversive and sustained appetite-suppressing signals, which discourages the initiation of feeding and drinking (fully recapitulating the symptoms of gastric distension) in part via signalling to the paraventricular hypothalamus. By contrast, inhibiting the same population of PBPdyn neurons induces overconsumption only if a drive for ingestion exists, which confirms that these neurons mediate negative feedback signalling. Our findings reveal a neural mechanism that underlies the mechanosensory monitoring of ingestion and negative feedback control of intake behaviours upon distension of the digestive tract.

Scalable and Isotropic Expansion of Tissues with Simply Tunable Expansion Ratio.

Tissue expansion techniques physically expand swellable gel-embedded biological specimens to overcome the resolution limit of light microscopy. As the benefits of expansion come at the expense of signal concentration, imaging volume and time, and mechanical integrity of the sample, the optimal expansion ratio may widely differ depending on the experiment. However, existing expansion methods offer only fixed expansion ratios that cannot be easily adjusted to balance the gain and loss associated with expansion. Here, a hydrogel conversion-based expansion method is presented, that enables easy adjustment of the expansion ratio for individual needs, simply by changing the duration of a heating step. This method, termed ZOOM, isotropically expands samples up to eightfold in a single expansion process. ZOOM preserves biomolecules for post-processing labelings and supports multi-round expansion for the imaging of a single sample at multiple zoom factors. ZOOM can be flexibly and scalably applied to nanoscale imaging of diverse samples, ranging from cultured cells to thick tissues, as well as bacteria, exoskeletal Caenorhabditis elegans, and human brain samples.