Fasting-Refeeding Impacts Immune Cell Dynamics and Mucosal Immune Responses.

Nutritional status potentially influences immune responses; however, how nutritional signals regulate cellular dynamics and functionality remains obscure. Herein, we report that temporary fasting drastically reduces the number of lymphocytes by ∼50% in Peyer's patches (PPs), the inductive site of the gut immune response. Subsequent refeeding seemingly restored the number of lymphocytes, but whose cellular composition was conspicuously altered. A large portion of germinal center and IgA+ B cells were lost via apoptosis during fasting. Meanwhile, naive B cells migrated from PPs to the bone marrow during fasting and then back to PPs during refeeding when stromal cells sensed nutritional signals and upregulated CXCL13 expression to recruit naive B cells. Furthermore, temporal fasting before oral immunization with ovalbumin abolished the induction of antigen-specific IgA, failed to induce oral tolerance, and eventually exacerbated food antigen-induced diarrhea. Thus, nutritional signals are critical in maintaining gut immune homeostasis.

p38α plays differential roles in hematopoietic stem cell activity dependent on aging contexts.

Hematopoietic stem cells (HSCs) and their progeny sustain lifetime hematopoiesis. Aging alters HSC function, number, and composition and increases risk of hematological malignancies, but how these changes occur in HSCs remains unclear. Signaling via p38 mitogen-activated kinase (p38MAPK) has been proposed as a candidate mechanism underlying induction of HSC aging. Here, using genetic models of both chronological and premature aging, we describe a multimodal role for p38α, the major p38MAPK isozyme in hematopoiesis, in HSC aging. We report that p38α regulates differentiation bias and sustains transplantation capacity of HSCs in the early phase of chronological aging. However, p38α decreased HSC transplantation capacity in the late progression phase of chronological aging. Furthermore, codeletion of p38α in mice deficient in ataxia-telangiectasia mutated, a model of premature aging, exacerbated aging-related HSC phenotypes seen in ataxia-telangiectasia mutated single-mutant mice. Overall, these studies provide new insight into multiple functions of p38MAPK, which both promotes and suppresses HSC aging context dependently.

Big Trajectory Data Mining: A Survey of Methods, Applications, and Services.

The increasingly wide usage of smart infrastructure and location-aware terminals has helped increase the availability of trajectory data with rich spatiotemporal information. The development of data mining and analysis methods has allowed researchers to use these trajectory datasets to identify urban reality (e.g., citizens' collective behavior) in order to solve urban problems in transportation, environment, public security, etc. However, existing studies in this field have been relatively isolated, and an integrated and comprehensive review is lacking the problems that have been tackled, methods that have been tested, and services that have been generated from existing research. In this paper, we first discuss the relationships among the prevailing trajectory mining methods and then, classify the applications of trajectory data into three major groups: social dynamics, traffic dynamics, and operational dynamics. Finally, we briefly discuss the services that can be developed from studies in this field. Practical implications are also delivered for participants in trajectory data mining. With a focus on relevance and association, our review is aimed at inspiring researchers to identify gaps among tested methods and guiding data analysts and planners to select the most suitable methods for specific problems.

Quantitative imaging mass spectroscopy reveals roles of heme oxygenase-2 for protecting against transhemispheric diaschisis in the brain ischemia.

Carbon monoxide-generating heme oxygenase-2 is expressed in neurons and plays a crucial role for regulating hypoxic vasodilation through mechanisms unlocking carbon monoxide-dependent inhibition of H2S-generating cystathionine ß-synthase expressed in astrocytes. This study aims to examine whether heme oxygenase-2 plays a protective role in mice against stroke. Focal ischemia was induced by middle cerebral artery occlusion. Regional differences in metabolites among ipsilateral and contralateral hemispheres were analysed by quantitative imaging mass spectrometry equipped with an image-processing platform to optimize comparison of local metabolite contents among different animals. Under normoxia, blood flow velocity in precapillary arterioles were significantly elevated in heme oxygenase-2-null mice vs controls, while metabolic intermediates of central carbon metabolism and glutamate synthesis were elevated in the brain of heme oxygenase-2-null mice, suggesting greater metabolic demands to induce hyperemia in these mice. In response to focal ischemia, heme oxygenase-2-null mice exhibited greater regions of ischemic core that coincide with notable decreases in energy metabolism in the contralateral hemisphere as well as in penumbra. In conclusion, these findings suggest that heme oxygenase-2 is involved in mechanisms by which not only protects against compromised energy metabolism of the ipsilateral hemisphere but also ameliorates transhemispheric diaschisis of the contralateral hemisphere in ischemic brain.

Abnormal hematopoiesis and hematopoietic stem cell niche.

During steady-state conditions, hematopoietic stem cells (HSCs) maintain a quiescent status in the cell cycle. Upon infection or inflammation, bone marrow HSCs begin proliferating and generating differentiated hematopoietic cells via multi-lineage differentiation and self-renewal; this effect is partially due to the alteration of their surrounding microenvironment or niche. In addition, recent studies have revealed that the bone marrow niche critically contributes to abnormal hematopoiesis, including leukemogenesis. In this review, we discuss the recent advances in our understanding of HSC/niche functions and the regulatory machineries employed during homeostasis, stress hematopoiesis, or disease conditions.

Hypoxia regulates the hematopoietic stem cell niche.

Bone marrow, the site of hematopoiesis throughout adulthood, is a physiologically hypoxic organ. Thus, various biological oxygen sensors and their signaling cascades play a pivotal role in hematopoietic systems in the bone marrow under both physiologic and pathologic conditions. Hypoxia-inducible factors (HIFs) are hypoxic stress sensor proteins that are stabilized under homeostatic or stress-induced hypoxia. In the hypoxic bone marrow, HIFs play crucial roles in hematopoietic stem cells (HSCs) and in the cells of the HSC niche. The signals downstream of the HIFs maintain HSC quiescence, survival, and metabolic homeostasis through both cell-autonomous and non-cell-autonomous mechanisms. Leukemic stem cells (LSCs) hijack these delicate hypoxia-sensing mechanisms to sustain their self-renewal potential, promoting disease progression and drug resistance even under normoxic conditions. This review focuses on HIF-mediated oxygen-sensing mechanisms of adult HSCs and LSCs and their niche cells in the hypoxic bone marrow.

Leukocyte plugging and cortical capillary flow after subarachnoid hemorrhage.

BACKGROUND: It is believed that increased intracranial pressure immediately after subarachnoid hemorrhage (SAH) causes extensive brain ischemia and results in worsening clinical status. Arterial flow to the cerebral surfaces is clinically well maintained during clipping surgery regardless of the severity of the World Federation of Neurological Societies grade after SAH. To explore what kinds of changes occur in the cortical microcirculation, not at the cerebral surface, we examined cortical microcirculation after SAH using two-photon laser scanning microscopy (TPLSM). METHODS: SAH was induced in mice with an endovascular perforation model. Following continuous injection of rhodamine 6G, velocities of labeled platelets and leukocytes and unlabeled red blood cells (RBCs) were measured in the cortical capillaries 60 min after SAH with a line-scan method using TPLSM, and the data were compared to a sham group and P-selectin monoclonal antibody-treated group. RESULTS: Velocities of leukocytes, platelets, and RBCs in capillaries decreased significantly 60 min after SAH. Rolling and adherent leukocytes suddenly prevented other blood cells from flowing in the capillaries. Flowing blood cells also decreased significantly in each capillary after SAH. This no-reflow phenomenon induced by plugging leukocytes was often observed in the SAH group but not in the sham group. The decreased velocities of blood cells were reversed by pretreatment with the monoclonal antibody of P-selection, an adhesion molecule expressed on the surfaces of both endothelial cells and platelets. CONCLUSIONS: SAH caused sudden worsening of cortical microcirculation at the onset. Leukocyte plugging in capillaries is one of the reasons why cortical microcirculation is aggravated after SAH.

Hypoxic regulation of the cerebral microcirculation is mediated by a carbon monoxide-sensitive hydrogen sulfide pathway.

Enhancement of cerebral blood flow by hypoxia is critical for brain function, but signaling systems underlying its regulation have been unclear. We report a pathway mediating hypoxia-induced cerebral vasodilation in studies monitoring vascular disposition in cerebellar slices and in intact mouse brains using two-photon intravital laser scanning microscopy. In this cascade, hypoxia elicits cerebral vasodilation via the coordinate actions of H(2)S formed by cystathionine ß-synthase (CBS) and CO generated by heme oxygenase (HO)-2. Hypoxia diminishes CO generation by HO-2, an oxygen sensor. The constitutive CO physiologically inhibits CBS, and hypoxia leads to increased levels of H(2)S that mediate the vasodilation of precapillary arterioles. Mice with targeted deletion of HO-2 or CBS display impaired vascular responses to hypoxia. Thus, in intact adult brain cerebral cortex of HO-2-null mice, imaging mass spectrometry reveals an impaired ability to maintain ATP levels on hypoxia.

SDHAF1 confers metabolic resilience to aging hematopoietic stem cells by promoting mitochondrial ATP production.

Aging generally predisposes stem cells to functional decline, impairing tissue homeostasis. Here, we report that hematopoietic stem cells (HSCs) acquire metabolic resilience that promotes cell survival. High-resolution real-time ATP analysis with glucose tracing and metabolic flux analysis revealed that old HSCs reprogram their metabolism to activate the pentose phosphate pathway (PPP), becoming more resistant to oxidative stress and less dependent on glycolytic ATP production at steady state. As a result, old HSCs can survive without glycolysis, adapting to the physiological cytokine environment in bone marrow. Mechanistically, old HSCs enhance mitochondrial complex II metabolism during stress to promote ATP production. Furthermore, increased succinate dehydrogenase assembly factor 1 (SDHAF1) in old HSCs, induced by physiological low-concentration thrombopoietin (TPO) exposure, enables rapid mitochondrial ATP production upon metabolic stress, thereby improving survival. This study provides insight into the acquisition of resilience through metabolic reprogramming in old HSCs and its molecular basis to ameliorate age-related hematopoietic abnormalities.

Context-dependent modification of PFKFB3 in hematopoietic stem cells promotes anaerobic glycolysis and ensures stress hematopoiesis.

Metabolic pathways are plastic and rapidly change in response to stress or perturbation. Current metabolic profiling techniques require lysis of many cells, complicating the tracking of metabolic changes over time after stress in rare cells such as hematopoietic stem cells (HSCs). Here, we aimed to identify the key metabolic enzymes that define differences in glycolytic metabolism between steady-state and stress conditions in murine HSCs and elucidate their regulatory mechanisms. Through quantitative 13C metabolic flux analysis of glucose metabolism using high-sensitivity glucose tracing and mathematical modeling, we found that HSCs activate the glycolytic rate-limiting enzyme phosphofructokinase (PFK) during proliferation and oxidative phosphorylation (OXPHOS) inhibition. Real-time measurement of ATP levels in single HSCs demonstrated that proliferative stress or OXPHOS inhibition led to accelerated glycolysis via increased activity of PFKFB3, the enzyme regulating an allosteric PFK activator, within seconds to meet ATP requirements. Furthermore, varying stresses differentially activated PFKFB3 via PRMT1-dependent methylation during proliferative stress and via AMPK-dependent phosphorylation during OXPHOS inhibition. Overexpression of Pfkfb3 induced HSC proliferation and promoted differentiated cell production, whereas inhibition or loss of Pfkfb3 suppressed them. This study reveals the flexible and multilayered regulation of HSC glycolytic metabolism to sustain hematopoiesis under stress and provides techniques to better understand the physiological metabolism of rare hematopoietic cells.

Subjective evaluations of self and others' driving behaviors: A comparative study involving data from drivers in Japan, China, and Vietnam.

INTRODUCTION: This study explored the influence of personal attributes on subjectively-reported aggressive driving behaviors, with an emphasis on the inter-influences between subjectively-reported aggressive driving behaviors between self and other individuals. To determine this, a survey was conducted comprising participants' socio-demographic data, information on their history with automotive accidents, and subjective scales to report on the driving behaviors between self and others. More specifically, a four-factor shortened version of the Manchester Driver Behavior Questionnaire was used to collect data on the aberrant driving behaviors of "self" and "others." METHOD: Participants were recruited from three countries, namely, Japan (1,250 responses), China (1,250), and Vietnam (1,000). This study only considered the "aggressive violations' factor," which was referred to as self-aggressive driving behaviors (SADB) and others' aggressive driving behaviors (OADB). After collecting the data, univariate and bivariate multiple regression models were employed to better understand the response patterns from both scales. RESULTS: This study found that accident experience had the strongest influence on the reporting of aggressive driving behaviors (followed by education level). However, variation in countries was also found between both the rate of engagement in aggressive driving behavior and its recognition. In this study, highly educated Japanese drivers tended to evaluate others as safe, whereas highly educated Chinese drivers tended to evaluate others as aggressive. This discrepancy can likely be attributed to cultural norms and values. Meanwhile, evaluations from Vietnamese drivers seemed to differ depending on whether they drove cars or bikes, with additional influences as a result of the driving frequency. Furthermore, this study found that it was most difficult to explain the driving behaviors on the "other" scale reported by Japanese drivers. PRACTICAL APPLICATIONS: These findings can aid policymakers and planners to develop road safety measures that reflect the behaviors of drivers in their respective countries.

Quantitative Analysis of Sympathetic and Nociceptive Innervation Across Bone Marrow Regions in Mice.

Bone marrow (BM) innervation regulates the mobilization of hematopoietic stem and progenitor cells (HSPCs) from BM and stress hematopoiesis either by acting directly on HSPCs or by altering the niche function of mesenchymal and endothelial cells. However, the spatial distribution of BM innervation across bone regions is yet to be fully elucidated. Thus, we aimed to characterize the distribution of sympathetic and nociceptive nerves in each bone and BM region using three-dimensional quantitative microscopy. We discovered that sympathetic and nociceptive nerves were the major fibers throughout the BM. Compared with other femoral regions, central parts of the femoral BM were more densely innervated by both sympathetic and nociceptive nerves. Each region of the sternum was similarly innervated by sympathetic and nociceptive nerves. Further, the majority of sympathetic and nociceptive nerves in the BM ran parallel with arteries and arterioles, whereas the degree varied according to the bone type or BM region. In conclusion, this study provides spatial, topological, and functional information on BM innervation in a quantitative manner and illustrates that sympathetic and nociceptive nerves are two major components in BM innervation, mostly associated with arteries and arterioles.

The effects of cilostazol on tissue oxygenation upon an ischemic-reperfusion injury in the mouse cerebrum.

Although cilostazol, an inhibitor of cyclic nucleotide phosphodiesterase 3 (PDE3), is known to exert a potent antiplatelet function by raising intracellular cAMP concentration, its effect on cerebral microcirculation upon an ischemic insult is not clearly understood. To examine effects of cilostazol on the global ischemic injury in the brain, we first measured the plasma leakage using modified Miles assay after mice had been subjected to 60 min of a bilateral common carotid artery (BCCA) occlusion followed by reperfusion for 4 h. Oral treatment with cilostazol (30 mg/kg) significantly increased plasma leakage. This result led us to examine if the treatment with cilostazol recruits more capillaries leading to an increase in surface area for exchange and oxygen transport to tissues. To do so, we simultaneously measured degrees of tissue hypoxia and vessel perfusion. Pimonidazol was injected intraperitoneally 1 h before sacrifice and capillary patency was assessed by fluorescein isothiocyanate-labeled Lycopersicon esculentum lectin bound to the endothelial surface. Treatment with cilostazol markedly increased the capillary patency which was accompanied by a reduction in the hypoxic area. Although the treatment with cilostazol caused an increase in the flux of plasma proteins across endothelial barrier that may imply an adverse role after a BCCA occlusion, this increase in protein leakage was attributable to the increased surface area for exchange which in turn brought about a reduction in tissue hypoxia. Taken together cilostazol appears to produce a protective effect against the ischemic-reperfusion injury.

Influence of personality traits on aberrant driving behaviors: A comparison of Japanese, Chinese, and Vietnamese drivers.

INTRODUCTION: This study aims to explore the influence of Big Five personality traits in combination with various socio-demographic factors and experiences of accident involvement on aberrant driving behaviors. The study also compares the effects of the level of development (i.e., developed or developing) of three countries on the personality traits and driving behaviors. METHOD: The four-factor Driver Behavior Questionnaire was used to collect data on aberrant driving behaviors, while a short version of the 10-item Big Five Inventory was used to collect data on personality traits. Responses were collected from Japan (1,250 responses), China (1,250), and Vietnam (1,000). A latent variable model was applied after controlling data in each category (e.g., age). RESULTS: This study revealed that respondents who experienced accidents in the past and scored higher on Agreeableness were less likely to commit aggressive violations in Japan, China, and Vietnam. Further, Japanese and Vietnamese female drivers who scored high on Conscientiousness were found to be less likely to commit ordinary violations. Neuroticism was positively correlated with aggressive violations only in the case of Vietnamese drivers, irrespective of the history of accident involvement. CONCLUSIONS: Drivers with particular personality types that are linked with aberrant driving behavior may need to receive additional training on behavior management. Practical Applications: This study may help road traffic policymakers predict future driving behaviors of Vietnamese and Chinese drivers based on those of Chinese and Japanese drivers, respectively, and act accordingly.

Identification and local manipulation of bone marrow vasculature during intravital imaging.

Physiological regulation of blood flow in bone marrow is important to maintain oxygen and glucose supplies but also the physiological hypoxic state of the hematopoietic stem cell (HSC) niche. However, regulatory mechanisms underlying microcirculation in the bone marrow (BM) niche remain unclear. Here, we identify vessels functioning in control of blood flow in bone marrow and assess their contractility. To evaluate contractile potential of Alexa Fluor 633 (AF633; an arterial marker)-positive vessels, we performed immunohistochemistry for α-smooth muscle actin (α-SMA) and found it expressed around AF633+ vessels in the femoral and calvarial marrow. To validate AF633+ vessel contractility, we developed a simple system to locally administer vasoactive agents that penetrate BM through transcalvarial vessels. After exposure of the calvarial surface to FITC-dextran (70 kDa), FITC intensity in calvarial bone marrow gradually increased. When we evaluated the effect of transcalvarial administration (TCA) of norepinephrine (NE) on vascular tone of AF633+ arteries and behavior of transplanted blood cells, NE administration decreased artery diameter and transendothelial migration of transplanted cells, suggesting that adrenergic signaling regulates the HSC niche microcirculation and blood cell migration into the BM via effects on BMarteries. We conclude that TCA is a useful tool for bone marrow research.

Dataset on commuting patterns and mode-switching behavior under prospective policy scenarios for public transport.

This paper covers a broadly used methodology used in travel behavior research aiming at determining individual and alternative-specific variables that influence the choice of the transportation mode for commuting trips. Data used in the analysis were obtained in July 2015 by means of a computer-assisted telephonic interview survey conducted in Cluj Metropolitan Area, Romania. The survey collected a wide range of day-by-day travel patterns, socioeconomic data, and attitudes and perceptions toward urban transportation services. Given the lack of studies from emerging, post-socialist countries, the survey assigned a section dedicated to an alternative ticketing policy for public transport services in order to evaluate the willingness of commuters to switch to a more sustainable transportation through non-coercive interventions. A revealed preference - stated preference modelling methodology was adopted in order to reveal the role of socioeconomic characteristics, along with features of transport supply and built environment in explaining commuting patterns and forecast sustainable modal splits. Both the survey and the methodology are scalable and flexible to be used, adapted, and applied in a wide range of transport policies regarding modal shifting strategies.

Potential involvement of semaphorin 3A in maintaining intervertebral disc tissue homeostasis.

Intervertebral discs (IVDs) are avascular; however, ingrowth of blood vessels into their outer regions has been noted during the progression of degeneration. The mechanisms underlying vascularization in IVD degeneration are not completely understood. Semaphorin 3A (Sema3A), originally characterized as a chemorepulsive factor for growing axons in the developing nervous system, inhibits angiogenesis. This study aimed to elucidate the potential involvement of Sema3A in maintaining tissue homeostasis within the avascular IVD. We demonstrated that the mRNA expression of Sema3A was higher in rat annulus fibrosus (AF) than in nucleus pulposus (NP) and that its expression level decreased with age. Both mRNA and protein expression level of Sema3A was also markedly suppressed in AF tissues of a rat IVD degeneration model. Both real-time RT-PCR and Western blot clearly indicated that Sema3A expression significantly reduced by treating inflammatory cytokines in rat AF cells. In a gain- and loss-of-function study, we observed that Sema3A reduced the catabolic shift in rat AF cells. In addition, our results indicated that Sema3A potentially inhibited the IL-6/JAK/STAT pathway. Finally, BrdU assay and tube formation assay revealed that treatment of recombinant Sema3A significantly blocks both proliferation and tube formation of HUVEC. Our results indicate that Sema3A may help maintain IVD tissue homeostasis. Thus, although further studies are needed, Sema3A may be a potential molecular target for suppressing IVD degeneration. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Environmental Optimization Enables Maintenance of Quiescent Hematopoietic Stem Cells Ex Vivo.

Hematopoietic stem cells (HSCs) maintain lifelong hematopoiesis by remaining quiescent in the bone marrow niche. Recapitulation of a quiescent state in culture has not been achieved, as cells rapidly proliferate and differentiate in vitro. After exhaustive analysis of different environmental factor combinations and concentrations as a way to mimic physiological conditions, we were able to maintain engraftable quiescent HSCs for 1 month in culture under very low cytokine concentrations, hypoxia, and very high fatty acid levels. Exogenous fatty acids were required likely due to suppression of intrinsic fatty acid synthesis by hypoxia and low cytokine conditions. By contrast, high cytokine concentrations or normoxia induced HSC proliferation and differentiation. Our culture system provides a means to evaluate properties of steady-state HSCs and test effects of defined factors in vitro under near-physiological conditions.

Gold-nanofève surface-enhanced Raman spectroscopy visualizes hypotaurine as a robust anti-oxidant consumed in cancer survival.

Gold deposition with diagonal angle towards boehmite-based nanostructure creates random arrays of horse-bean-shaped nanostructures named gold-nanofève (GNF). GNF generates many electromagnetic hotspots as surface-enhanced Raman spectroscopy (SERS) excitation sources, and enables large-area visualization of molecular vibration fingerprints of metabolites in human cancer xenografts in livers of immunodeficient mice with sufficient sensitivity and uniformity. Differential screening of GNF-SERS signals in tumours and those in parenchyma demarcated tumour boundaries in liver tissues. Furthermore, GNF-SERS combined with quantum chemical calculation identified cysteine-derived glutathione and hypotaurine (HT) as tumour-dominant and parenchyma-dominant metabolites, respectively. CD44 knockdown in cancer diminished glutathione, but not HT in tumours. Mechanisms whereby tumours sustained HT under CD44-knockdown conditions include upregulation of PHGDH, PSAT1 and PSPH that drove glycolysis-dependent activation of serine/glycine-cleavage systems to provide one-methyl group for HT synthesis. HT was rapidly converted into taurine in cancer cells, suggesting that HT is a robust anti-oxidant for their survival under glutathione-suppressed conditions.

Use of Imaging Techniques to Illuminate Dynamics of Hematopoietic Stem Cells and Their Niches.

Continuous generation of blood cells over an organism's lifetime is supported by hematopoietic stem/progenitor cells (HSPCs) capable of producing all hematopoietic cell subtypes. Adult mammalian HSPCs are localized to bone marrow and regulated by their neighboring microenvironment, or "niche." Because interactions of HSPCs with their niches are highly dynamic and complex, the recent development of imaging technologies provides a powerful new tool to understand stem cell/niche biology. In this review, we discuss recent advances in our understanding of dynamic HSPC/niche interactions during development, homeostasis, disease states or aging with a focus on studies advanced by imaging analysis. We also summarize methods to visualize HSPCs and niche cells in vivo, including use of HSPC reporter mice and chemical probes. Findings emerging from these investigations could suggest novel therapies for diseases and aging.