Remimazolam and Remifentanil Anesthetics for an Adolescent Patient with Stiff-Person Syndrome: A Case Report.

Stiff-person syndrome (SPS) is a rare autoimmune disease characterized by fluctuating rigidity and stiffness of the axial muscles. There are no reports on the use of remimazolam in a patient with SPS. A 16-year-old Japanese woman with SPS was scheduled to undergo intrathecal baclofen pump exchange. General anesthesia was induced and maintained using remimazolam, remifentanil, and intermittent rocuronium bromide. No intraoperative mobility or significant autonomic symptoms were observed. Additionally, electroencephalographic signature showed sufficient anesthetic depth. The patient's emergence from general anesthesia was uneventful. In conclusion, remimazolam could be considered an effective anesthetic drug for patients with SPS.

Repeated activation of C1 neurons in medulla oblongata decreases anti-inflammatory effect via the hypofunction of the adrenal gland adrenergic response.

The immune system is known to be controlled by the autonomic nervous system including sympathetic and parasympathetic (vagus) nerves. C1 neurons in the medulla oblongata, which participate in the control of the autonomic nervous system, are responders to stressors and regulate the immune system. Short-term activation of C1 neurons suppresses inflammation, while the effect of a long-term activation of these neurons on the inflammatory reflex is unclear. We, herein, demonstrate that the coactivation of both the splenic sympathetic nerves and the adrenal gland adrenergic response are indispensable for the prognosis of acute lung injury. The chemogenetic activation of C1 neurons increased plasma catecholamine including adrenaline and noradrenaline levels. The deletion of catecholaminergic cells using local injections of viral vector in the adrenal gland abolished the protective effect against acute lung injury when the C1 neurons were stimulated by either chemogenetic or optogenetic tools. Furthermore, repeated activation of C1 neurons using chemogenetic tool inhibited the adrenal response without affecting the plasma noradrenaline levels, eliminated the protective effect against acute lung injury. This was rescued by the isoprenaline administration. We concluded that the maintenance of an adrenergic response via C1 neurons in the adrenal gland is a prerequisite for the delivery of an effective anti-inflammatory response.

Lunar gravity prevents skeletal muscle atrophy but not myofiber type shift in mice.

Skeletal muscle is sensitive to gravitational alterations. We recently developed a multiple artificial-gravity research system (MARS), which can generate gravity ranging from microgravity to Earth gravity (1 g) in space. Using the MARS, we studied the effects of three different gravitational levels (microgravity, lunar gravity [1/6 g], and 1 g) on the skeletal muscle mass and myofiber constitution in mice. All mice survived and returned to Earth, and skeletal muscle was collected two days after landing. We observed that microgravity-induced soleus muscle atrophy was prevented by lunar gravity. However, lunar gravity failed to prevent the slow-to-fast myofiber transition in the soleus muscle in space. These results suggest that lunar gravity is enough to maintain proteostasis, but a greater gravitational force is required to prevent the myofiber type transition. Our study proposes that different gravitational thresholds may be required for skeletal muscle adaptation.

Galvanic vestibular stimulation-induced activation of C1 neurons in medulla oblongata protects against acute lung injury.

Autonomic nerves, including the sympathetic and parasympathetic nerves, control the immune system along with their physiological functions. On the peripheral side, the interaction between the splenic sympathetic nerves and immune cells is important for the anti-inflammatory effects. However, the central mechanism underlying these anti-inflammatory effects remains unclear. C1 neurons respond to stressors and subsequently determine the outflow of the autonomic nervous system. We have previously shown that C1 neurons protect against acute kidney injury and found a signaling connection between peripheral vestibular organs and C1 neurons. Thus, we hypothesized that hypergravity load or galvanic vestibular stimulation (GVS) might protect against acute lung injury. We showed that C1 neurons are histologically and functionally activated by stimulating the peripheral vestibular organs. Protection against acute lung injury that was induced by a 2 G load disappeared due to vestibular lesions or the deletion of C1 neurons. This GVS-induced protective effect was also eliminated by the deletion of the C1 neurons. Furthermore, GVS increased splenic sympathetic nerve activity in conscious mice, and splenic sympathetic denervation abolished the GVS-induced protection against acute lung injury. Therefore, the activated pathway between C1 neurons and splenic sympathetic nerves is indispensable for GVS-induced protection against acute lung injury.

Changes in metabolism and vestibular function depend on gravitational load in mice.

The vestibular system is known to participate in controlling posture and metabolism. Different gravitational environments, including microgravity or hypergravity, cause plastic alteration of the vestibular system, and plasticity is important for adaptation to a novel gravitational environment. However, it is unclear whether the degree of change in vestibular-related physiological function depends on gravitational loading. To examine this, we used a hypergravity environment including 1.33 G, 1.67 G, and 2 G for 29 days. We found that a gravitational threshold induces physiological changes, including vestibular-related posture control and metabolism in mice. Body mass did not return to the preloading level in 1.67 G and 2 G mice. A significant drop in food intake, observed on the first day of hypergravity load, disappeared in all mice after longer exposure. However, a reduction in water intake was sustained in 2 G mice but not 1.33 G and 1.67 G mice. Body temperature did not return to the preloading level in 2 G mice by the final day. A decrease in the skill of the righting reflex was observed in 2 G mice but not 1.33 G and 1.67 G mice. In conclusion, this study showed that hypergravity-induced changes in metabolism and vestibular function depended on the amount of gravitational loading. The 2 G load affected vestibular-related posture control and metabolism considerably, compared with 1.33 G and 1.67 G loads.NEW & NOTEWORTHY It is unclear whether the degree of change in vestibular-related physiological function depends on gravitational loading. Present study showed that exposure to hypergravity-induced degrees of change in metabolism and vestibular function depended on the gravitational loading. The response of body mass depended on the gravitational loading size. Especially in 2 G environment, water intake, body temperature, and vestibular function were influenced. These changes could involve plastic alteration of vestibular-related autonomic and motor functions.

Hypergravity load-induced hyperglycemia occurs due to hypothermia and increased plasma corticosterone level in mice.

Hypothermia has been observed during hypergravity load in mice and rats. This response is beneficial for maintaining blood glucose level, although food intake decreases. However, saving glucose is not enough to maintain blood glucose level during hypergravity load. In this study, we examined the contribution of humoral factors related to glycolysis in maintaining blood glucose level in a 2 G environment. Increased plasma corticosterone levels were observed in mice with intact peripheral vestibular organs, but not in mice with vestibular lesions. Plasma glucagon levels did not change, and decrease in plasma adrenaline levels was observed in mice with intact peripheral vestibular organs. Accordingly, it is possible that increase in plasma corticosterone level and hypothermia contribute to prevent hypoglycemia in a 2 G environment.

Study of mouse behavior in different gravity environments.

Many experiments have analyzed the effect of the space environment on various organisms. However, except for the group-rearing of mice in space, there has been little information on the behavior of organisms in response to gravity changes. In this study, we developed a simple Active Inactive Separation (AIS) method to extract activity and inactivity in videos obtained from the habitat cage unit of a space experiment. This method yields an activity ratio as a ratio of 'activity' within the whole. Adaptation to different gravitational conditions from 1g to hypergravity (HG) and from microgravity (MG) to artificial 1g (AG) was analyzed based on the amount of activity to calculate the activity ratio and the active interval. The result for the activity ratios for the ground control experiment using AIS were close to previous studies, so the effectiveness of this method was indicated. In the case of changes in gravity from 1g to HG, the ratio was low at the start of centrifugation, recovered sharply in the first week, and entered a stable period in another week. The trend in the AG and HG was the same; adapting to different gravity environments takes time.

Induced genetic ablation of Rest leads to the alteration of stimulus-induced response of the vagal nerve.

Rest (RE1-silencing transcription factor, also called Nrsf) is involved in the maintenance of the undifferentiated state of neuronal stem/progenitor cells by preventing precocious expression of neuronal genes. In order to further investigate the function of Rest in neurons, we generated and examined mice evoking genetic ablation of Rest specifically in neural tissues by generating Rest conditional knockout mice. As the Rest knockout mice are embryonically lethal, we used a Sox1-Cre allele to excise the floxed Rest gene from the early stage of nerve cell differentiation including neural crest-derived nerve cells. Using this conditional Rest knockout Sox1-Cre; Restflox/flox mice, we have revealed the role of Rest in the parasympathetic nervous system in the stomach and heart.

Roles of Olfactomedin 1 in Muscle and Bone Alterations Induced by Gravity Change in Mice.

Microgravity causes both muscle and bone loss. Although we previously revealed that gravity change influences muscle and bone through the vestibular system in mice, its detailed mechanism has not been elucidated. In this study, we investigated the roles of olfactomedin 1 (OLFM1), whose expression was upregulated during hypergravity in the soleus muscle, in mouse bone cells. Vestibular lesion significantly blunted OLFM1 expression in the soleus muscle and serum OLFM1 levels enhanced by hypergravity in mice. Moreover, a phosphatidylinositol 3-kinase inhibitor antagonized shear stress-enhanced OLFM1 expression in C2C12 myotubes. As for the effects of OLFM1 on bone cells, OLFM1 inhibited osteoclast formation from mouse bone marrow cells and mouse preosteoclastic RAW264.7 cells. Moreover, OLFM1 suppressed RANKL expression and nuclear factor-κB signaling in mouse osteoblasts. Serum OLFM1 levels were positively related to OLFM1 mRNA levels in the soleus muscle and trabecular bone mineral density of mice. In conclusion, we first showed that OLFM1 suppresses osteoclast formation and RANKL expression in mouse cells.

VGLUT2-expressing neurons in the vestibular nuclear complex mediate gravitational stress-induced hypothermia in mice.

The vestibular system, which is essential for maintaining balance, contributes to the sympathetic response. Although this response is involved in hypergravity load-induced hypothermia in mice, the underlying mechanism remains unknown. This study showed that hypergravity (2g) decreased plasma catecholamines, which resulted in hypoactivity of the interscapular brown adipose tissue (iBAT). Hypothermia induced by 2g load was significantly suppressed by administration of beta-adrenergic receptor agonists, suggesting the involvement of decrease in iBAT activity through sympathoinhibition. Bilateral chemogenetic activation of vesicular glutamate transporter 2 (VGLUT2)-expressing neurons in the vestibular nuclear complex (VNC) induced hypothermia. The VGLUT2-expressing neurons contributed to 2g load-induced hypothermia, since their deletion suppressed hypothermia. Although activation of vesicular gamma-aminobutyric acid transporter-expressing neurons in the VNC induced slight hypothermia instead of hyperthermia, their deletion did not affect 2g load-induced hypothermia. Thus, we concluded that 2g load-induced hypothermia resulted from sympathoinhibition via the activation of VGLUT2-expressing neurons in the VNC.

Roles of Dkk2 in the Linkage from Muscle to Bone during Mechanical Unloading in Mice.

Mechanical unloading simultaneously induces muscle and bone loss, but its mechanisms are not fully understood. The interactions between skeletal muscle and bone have been recently noted. Although canonical wingless-related integration site (Wnt)/ß-catenin signaling is crucial for bone metabolism, its roles in the muscle and bone interactions have remained unknown. Here, we performed comprehensive DNA microarray analyses to clarify humoral factors linking muscle to bone in response to mechanical unloading and hypergravity with 3 g in mice. We identified Dickkopf (Dkk) 2, a Wnt/ß-catenin signaling inhibitor, as a gene whose expression was increased by hindlimb unloading (HU) and reduced by hypergravity in the soleus muscle of mice. HU significantly elevated serum Dkk2 levels and Dkk2 mRNA levels in the soleus muscle of mice whereas hypergravity significantly decreased those Dkk2 levels. In the simple regression analyses, serum Dkk2 levels were negatively and positively related to trabecular bone mineral density and mRNA levels of receptor activator of nuclear factor-kappa B ligand (RANKL) in the tibia of mice, respectively. Moreover, shear stress significantly suppressed Dkk2 mRNA levels in C2C12 cells, and cyclooxygenase inhibitors significantly antagonized the effects of shear stress on Dkk2 expression. On the other hand, Dkk2 suppressed the mRNA levels of osteogenic genes, alkaline phosphatase activity and mineralization, and it increased RANKL mRNA levels in mouse osteoblasts. In conclusion, we showed that muscle and serum Dkk2 levels are positively and negatively regulated during mechanical unloading and hypergravity in mice, respectively. An increase in Dkk2 expression in the skeletal muscle might contribute to disuse- and microgravity-induced bone and muscle loss.

Understanding vestibular-related physiological functions could provide clues on adapting to a new gravitational environment.

The peripheral vestibular organs are sensors for linear acceleration (gravity and head tilt) and rotation. Further, they regulate various body functions, including body stability, ocular movement, autonomic nerve activity, arterial pressure, body temperature, and muscle and bone metabolism. The gravitational environment influences these functions given the highly plastic responsiveness of the vestibular system. This review demonstrates that hypergravity or microgravity induces changes in vestibular-related physiological functions, including arterial pressure, muscle and bone metabolism, feeding behavior, and body temperature. Hopefully, this review contributes to understanding how human beings can adapt to a new gravitational environment, including the moon and Mars, in future.

Roles of the vestibular system in obesity and impaired glucose metabolism in high-fat diet-fed mice.

The vestibular system controls balance, posture, blood pressure, and gaze. However, the roles of the vestibular system in energy and glucose metabolism remain unknown. We herein examined the roles of the vestibular system in obesity and impaired glucose metabolism using mice with vestibular lesions (VL) fed a high-sucrose/high-fat diet (HSHFD). VL was induced by surgery or arsenic. VL significantly suppressed body fat enhanced by HSHFD in mice. Glucose intolerance was improved by VL in mice fed HSHFD. VL blunted the levels of adipogenic factors and pro-inflammatory adipokines elevated by HSHFD in the epididymal white adipose tissue of mice. A ß-blocker antagonized body fat and glucose intolerance enhanced by HSHFD in mice. The results of an RNA sequencing analysis showed that HSHFD induced alterations in genes, such as insulin-like growth factor-2 and glial fibrillary acidic protein, in the vestibular nuclei of mice through the vestibular system. In conclusion, we herein demonstrated that the dysregulation of the vestibular system influences an obese state and impaired glucose metabolism induced by HSHFD in mice. The vestibular system may contribute to the regulation of set points under excess energy conditions.

Mechanism underlying the negative inotropic effect in rat left ventricle in hyperthermia: the role of TRPV1.

We have previously reported that the negative inotropic effects of hyperthermia (42 °C) on left ventricular (LV) mechanoenergetics using the excised, cross-circulated rat heart model. Here, we investigated the role of TRPV1 on LV mechanoenergetics in hyperthermia. We analyzed the LV end-systolic pressure-volume relation (ESPVR) and the linear relation between the myocardial oxygen consumption per beat (VO2) and the systolic pressure-volume area (PVA; a total mechanical energy per beat) during infusion of capsazepine (CPZ) in hyperthermia, or capsaicin (Cap) under 300 bpm pacing. LV ESP decreased in each LV volume and the resultant downward-shift of LV ESPVR was suppressed by CPZ infusion in hyperthermia-hearts. In Cap-treated hearts, LV ESPVR shifted downward from the control ESPVR, similar to hyperthermia-hearts. The slopes of VO2-PVA relationship were unchanged. The VO2 intercepts in hyperthermia-hearts did not decrease because of decreased E-C coupling VO2, and inversely increased basal metabolic VO2, which was suppressed by CPZ, though the VO2 intercepts in Cap-treated hearts significantly decreased. The levels of phosphorylated phospholamban at serine 16 decreased significantly in hyperthermia-hearts, as well as Cap-treated hearts. These results indicate that a Cap-induced decrease in the LV contractility, like in cases of hyperthermia, are due to the down-regulation of the total calcium handling in E-C coupling, suggesting that negative inotropic effect in hyperthermia-heart is, at least in part, mediated through TRPV1 signaling pathway.

Proteomic analysis revealed different responses to hypergravity of soleus and extensor digitorum longus muscles in mice.

Investigating protein abundance profiles is important to understand the differences in the slow and fast skeletal muscle characteristics. The profiles in soleus (Sol) and extensor digitorum longus (EDL) muscles in mice exposed to 1 g or 3 g for 28 d were compared. The biological implications of the profiles revealed that hypergravity exposure activated a larger number of pathways involved in protein synthesis in Sol. In contrast, the inactivation of signalling pathways involved in oxidative phosphorylation were conspicuous in EDL. These results suggested that the reactivity of molecular pathways in Sol and EDL differed. Additionally, the levels of spermidine synthase and spermidine, an important polyamine for cell growth, increased in both muscles following hypergravity exposure, whereas the level of spermine oxidase (SMOX) increased in EDL alone. The SMOX level was negatively correlated with spermine content, which is involved in muscle atrophy, and was higher in EDL than Sol, even in the 1 g group. These results indicated that the contribution of SMOX to the regulation of spermidine and spermine contents in Sol and EDL differed. However, contrary to expectations, the difference in the SMOX level did not have a significant impact on the growth of these muscles following hypergravity exposure. SIGNIFICANCE: The skeletal muscle-specific protein abundance profiles result in differences in the characteristics of slow and fast skeletal muscles. We investigated differences in the profiles in mouse slow-twitch Sol and fast-twitch EDL muscles following 28-d of 1 g and 3 g exposure by LC-MS/MS analysis and label-free quantitation. A two-step solubilisation of the skeletal muscle proteins increased the coverage of proteins identified by LC-MS/MS analysis. Additionally, this method reduced the complexity of samples more easily than protein or peptide fractionation by SDS-PAGE and offline HPLC while maintaining the high operability of samples and was reproducible. A larger number of hypergravity-responsive proteins as well as a prominent increase in the wet weights was observed in Sol than EDL muscles. The biological implications of the difference in the protein abundance profiles in 1 g and 3 g groups revealed that the reactivity of each molecular pathway in Sol and EDL muscles to hypergravity exposure differed significantly. In addition, we found that the biosynthetic and interconversion pathway of polyamines, essential factors for cell growth and survival in mammals, was responsive to hypergravity exposure; spermidine and spermine contents in Sol and EDL muscles were regulated by different mechanisms even in the 1 g group. However, our results indicated that the difference in the mechanism regulating polyamine contents is unlikely to have a significant effect on the differences in Sol and EDL muscle growth following hypergravity exposure.

Hypergravity-induced plastic alteration of the vestibulo-sympathetic reflex involves decrease in responsiveness of CAMK2-expressing neurons in the vestibular nuclear complex.

The vestibular system contributes to not only eye movement and posture but also the sympathetic response. Plastic alteration of the vestibulo-sympathetic reflex is induced by hypergravity load; however, the mechanism remains unknown. Here, we examined 2 g-induced changing in responsiveness of CAMK2-expressing neurons in the vestibular nucleus complex using optogenetic tools. The excitatory photostimulation of the CAMK2-expressing neurons in the unilateral vestibular nuclear complex induced body tilt to the contralateral side, while inhibitory photostimulation showed the opposite response. Photoactivation of either cell body or the axonal terminal in the rostral ventrolateral medulla showed sympathoexcitation followed by the pressor response. Furthermore, this response was significantly attenuated (49.8 ± 4%) after the 1st day of 2 g loading, and this value was further reduced by the 5th day (22.4 ± 3%), suggesting that 2 g-induced attenuation of the vestibulo-sympathetic reflex involves at least decrease in responsiveness of CAMK2-expressing neurons in the vestibular nuclear complex.

The energy-saving effect of a new myosin activator, omecamtiv mecarbil, on LV mechanoenergetics in rat hearts with blood-perfused isovolumic contraction model.

A novel myosin activator, omecamtiv mecarbil (OM), is a cardiac inotropic agent with a unique new mechanism of action, which is thought to arise from an increase in the transition rate of myosin into the actin-bound force-generating state without increasing calcium (Ca2+) transient. There remains, however, considerable controversy about the effects of OM on cardiac contractility and energy expenditure. In the present study, we investigated the effects of OM on left ventricular (LV) mechanical work and energetics, i.e., mechanoenergetics in rat normal hearts (CTL) and failing hearts induced by chronic administration of isoproterenol (1.2 mg/kg/day) for 4 weeks (ISO-HF). We analyzed the LV end-systolic pressure-volume relation (ESPVR) and the linear relation between the myocardial oxygen consumption per beat (VO2) and systolic pressure-volume area (PVA; a total mechanical energy per beat) in isovolumically contracting rat hearts at 240- or 300-bpm pacing in the absence or presence of OM. OM did not change the ESPVR in CTL and ISO-HF. OM, however, significantly decreased the slope of VO2-PVA relationship in both CTL and ISO-HF, and significantly increased the mean VO2 intercept without changes in basal metabolism in ISO-HF. These results suggested that OM improved the oxygen cost of PVA (contractile efficiency) with the unchanged LV contractility in both CTL and ISO-HF but increased VO2 for Ca2+ handling in excitation-contraction (E-C) coupling in ISO-HF. We concluded that OM improves contractile efficiency in normal and failing hearts but increases O2 consumption of Ca2+ handling in failing hearts in isovolumically contracting rat model.

FGF2-responsive genes in human dental pulp cells assessed using a rat spinal cord injury model.

The central nervous system in adult mammals does not heal spontaneously after spinal cord injury (SCI). However, SCI treatment has been improved recently following the development of cell transplantation therapy. We recently reported that fibroblast growth factor (FGF) 2-pretreated human dental pulp cells (hDPCs) can improve recovery in a rat model of SCI. This study aimed to investigate mechanisms underlying the curative effect of SCI enhanced via FGF2 pretreatment; we selected three hDPC lines upon screening for the presence of mesenchymal stem cell markers and of their functionality in a rat model of SCI, as assessed using the Basso, Beattie, and Bresnahan score of locomotor functional scale, electrophysiological tests, and morphological analyses. We identified FGF2-responsive genes via gene expression analyses in these lines. FGF2 treatment upregulated GABRB1, MMP1, and DRD2, which suggested to contribute to SCI or central the nervous system. In an expanded screening of additional lines, GABRB1 displayed rather unique and interesting behavior; two lines with the lowest sensitivity of GABRB1 to FGF2 treatment displayed an extremely minor effect in the SCI model. These findings provide insights into the role of FGF2-responsive genes, especially GABRB1, in recovery from SCI, using hDPCs treated with FGF2.

Left ventricular mechanoenergetics in excised, cross-circulated rat hearts under hypo-, normo-, and hyperthermic conditions.

We investigated the effects of altering cardiac temperature on left ventricular (LV) myocardial mechanical work and energetics using the excised, cross-circulated rat heart model. We analyzed the LV end-systolic pressure-volume relationship (ESPVR) and linear relationship between myocardial oxygen consumption per beat (VO2) and systolic pressure-volume area (PVA; total mechanical energy per beat) in isovolumically contracting rat hearts during hypo- (32 °C), normo- (37 °C), and hyperthermia (42 °C) under a 300-beats per minute pacing. LV ESPVR shifted downward with increasing cardiac temperature. The VO2-PVA relationship was superimposable in these different thermal conditions; however, each data point of VO2-PVA shifted left-downward during increasing cardiac temperature on the superimposable VO2-PVA relationship line. VO2 for Ca2+ handling in excitation-contraction coupling decreased, which was associated with increasing cardiac temperature, during which sarcoplasmic reticulum Ca2+-ATPase (SERCA) activity was suppressed, due to phospholamban phosphorylation inhibition, and instead, O2 consumption for basal metabolism was increased. The O2 cost of LV contractility for Ca2+ also increased with increasing cardiac temperature. Logistic time constants evaluating LV relaxation time were significantly shortened with increasing cardiac temperature related to the acceleration of the detachment in cross-bridge (CB) cycling, indicating increased myosin ATPase activity. The results suggested that increasing cardiac temperature induced a negative inotropic action related to SERCA activity suppression in Ca2+ handling and increased myosin ATPase activity in CB cycling. We concluded that thermal intervention could modulate cardiac inotropism by changing CB cycling, Ca2+ handling, and basal metabolism in rat hearts.