The introduction of combined anti-retroviral therapy (cART) in 1996, along with a continual breakthrough in anti-human immunodeficiency virus-1 (HIV-1) drugs, has improved the life expectancies of HIV-1-infected individuals. However, the incidence of drug-resistant viruses between individuals undergoing cART and treatment-naïve individuals is a common challenge. Therefore, there is a requirement to explore potential drug targets by considering various stages of the viral life cycle. For instance, the late stage, or viral release stage, remains uninvestigated extensively in antiviral drug discovery. In this study, we prepared a natural plant library and selected candidate plant extracts that inhibited HIV-1 release based on our laboratory-established screening system. The plant extracts from Epilobium hirsutum L. and Chamerion angustifolium (L.) Holub, belonging to the family Onagraceae, decreased HIV-1 release and accelerated the apoptosis in HIV-1-infected T cells but not uninfected T cells. A flavonol glycoside quercetin with oenothein B in Onagraceae reduced HIV-1 release in HIV-1-infected T cells. Moreover, extracts from Chamerion angustifolium (L.) Holub and Senna alexandrina Mill. inhibited the infectivity of progeny viruses. Together, these results suggest that C. angustifolium (L.) Holub contains quercetin with oenothein B that synergistically blocks viral replication and kills infected cells via an apoptotic pathway. Consequently, the plant extracts from the plant library of Turkey might be suitable candidates for developing novel anti-retroviral drugs that target the late phase of the HIV-1 life cycle.

Although polymethoxyflavones have been reported to exhibit various pharmacological actions, the effects of polymethoxyflavones sudachitin and demethoxysudachitin from the peel of Citrus sudachi on the cardiovascular system have not been clarified. This study investigated the mechanisms of vasorelaxation induced by sudachitin and demethoxysudachitin in rat aorta. Both compounds inhibited phenylephrine-induced contractions in a concentration-dependent manner. This was also observed in the case of potassium chloride (KCl)-induced contractions although the inhibitory effect was weak. In both contraction types, no differences were found in the inhibitory effects of sudachitin and demethoxysudachitin between endothelium-intact and -denuded aorta. The relaxant effects of sudachitin in endothelium-intact aortas were not affected by the nitric oxide synthase inhibitor N-nitro-L-arginine methyl ester hydrochloride (L-NAME) or the cyclooxygenase inhibitor indomethacin. In endothelium-denuded aorta, propranolol did not affect the relaxant effect of sudachitin. Both the adenylate cyclase activator forskolin- and soluble guanylate cyclase activator sodium nitroprusside-induced relaxant effects were potentiated by preincubation of sudachitin. Furthermore, the relaxant effect of sudachitin was not affected by the adenylate and guanylate cyclase inhibitors SQ22536 and or 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxaline-1-one (ODQ), respectively. Finally, we examined the effect of phosphodiesterase inhibition. Phosphodiesterase inhibitors (3-isobutyl-1-methylxanthine, cilostamide or sildenafil) alone, sudachitin alone, and a combination of phosphodiesterase inhibitors with sudachitin exhibited relaxant effects, while the lack of any interaction between each phosphodiesterase inhibitor and sudachitin indicated an additive effect between the two substance categories. These results suggest that sudachitin and demethoxysudachitin cause endothelial-independent relaxation, and that the mechanism of vasorelaxation by sudachitin is associated with the enhancement of cAMP- and guanosine 3′,5′-cyclic monophosphate (cGMP)-dependent pathways.

The involvement of serotonin (5-HT) and/or noradrenaline in acute pruriceptive processing in the central nervous system (CNS) has been reported using antidepressants, such as milnacipran, a serotonin and noradrenaline reuptake inhibitor, and mirtazapine, a noradrenergic and specific serotonergic antidepressant; however, the roles of 5-HT receptor family in acute pruriceptive processing have not been fully elucidated in the CNS. In the present study, scratching behavior induced by chloroquine (CQ) was ameliorated by milnacipran or mirtazapine, and these effects were reversed by SB207266, a 5-HT₄ antagonist, or SB258585, a 5-HT₆ antagonist, but not by SB258585, a 5-HT₅ antagonist. Moreover, CQ-induced scratches were mitigated by intrathecal injection of 5-HT₄ agonists, such as BIMU8 and ML10302, and the 5-HT₆ agonist, WAY208466. Conversely, histamine-induced scratches were not affected by the 5-HT₄ agonists or a 5-HT₆ agonist. Similarly, the amelioration of histamine-induced scratches by these antidepressants was not reversed by the 5-HT₄, 5-HT₅, or 5-HT₆ receptor antagonist. Therefore, 5-HT is involved in the amelioration of CQ-induced scratches by milnacipran and mirtazapine, and 5-HT₄, 5-HT₅, and 5-HT₆ receptors play differential roles in acute pruriceptive processing after administration of CQ or histamine.

The modified Cockcroft–Gault (CG) equation, previously developed for an aged-oriented cohort, was validated in a newly obtained dataset. Estimates of creatinine clearance (CCr) using this equation were found to be more accurate than those determined using the conventional CG equation, particularly for patients exceeding 65 years of age. We identified a subset of patients in this cohort whose estimates were inadequate. Using statistical analysis, we found that the deviation from estimates was attributed to a decreased albumin level. In addition, we determined a reduced albumin cutoff value for the modified CG equation to obtain a good estimate. Univariate linear regression analysis was applied to measure the CCr in this cohort and identify parameters related to body composition, and we found that extracellular water (ECW)/total body water (TBW) and body fat (%) were relevant. Using measured values of ECW/TBW and body fat (%), a multivariate linear regression (MLR) estimating equation was developed based on the modified CG equation. This equation was applied to a cohort over 65 years of age, and it was found that a good estimate was obtained for older patients with low albumin levels. Thus, we propose a flow diagram that illustrates conditions for selecting an appropriate estimating equation from among the CG, modified CG, and MLR equations.

Several cases of severe hyponatremia induced by linezolid (LZD) were reported. However, severe infections could also cause hyponatremia by increasing vasopressin secretion. To prove that hyponatremia is associated with LZD rather than infection, we compared the incidence and risk of developing hyponatremia between patients receiving LZD and those receiving vancomycin (VCM). A retrospective, single-center, observational cohort study was conducted in patients aged 18 years or older who received intravenous LZD or VCM for 7 d or longer. Hyponatremia was defined as serum sodium level lower than 134 mEq/L and more than 5% decrease from baseline after treatment initiation. The incidence and risk of developing hyponatremia were analyzed between LZD and VCM groups using chi-square test. Four hundred and fifty patients who satisfied the selection criteria were divided into LZD (n = 97) and VCM groups (n = 353). Significant differences in patient characteristics between LZD and VCM groups were observed before propensity score matching, but no significant differences were found after matching. LZD group showed a significantly higher incidence and risk of developing hyponatremia compared to VCM group both before (LZD: 16.5%, VCM: 5.4%; p < 0.001, odds ratio 3.472 [95% confidence interval (CI) 1.711–7.048]) and after (LZD: 17.8%, VCM: 5.5%; p = 0.020, odds ratio 3.738 [95% CI 1.157–12.076]) propensity score matching. In conclusion, propensity score analyses suggest that the risk of hyponatremia associated with LZD is approximately 3.7-fold higher than that associated with VCM, regardless of patient background.

Despite the fact that liver fibrosis is an intractable disease with a poor prognosis, effective therapeutic agents are not available. In this study, we focused on bone morphogenetic factor 7 (BMP7) that inhibits transforming growth factor (TGF)-β signaling, which is involved in liver fibrosis. We prepared an albumin-fused BMP7 (HSA-BMP7) that is retained in the blood and evaluated its inhibitory effect on liver fibrosis. Bile duct ligated mice were used as an acute liver fibrosis model, and carbon tetrachloride-induced liver fibrosis mice were used as a chronic model. All mice were administered HSA-BMP7 once per week. In the mice with bile duct ligation, the administration of HSA-BMP7 significantly suppressed the infiltration of inflammatory cells, the area of fibrosis around the bile duct, and decreased in the level of hydroxyproline as compared with saline administration. The mRNA expression of TGF-β and its downstream fibrosis-associated genes (α-SMA and Col1a2) were also suppressed by the administration of HSA-BMP7. In the carbon tetrachloride-induced liver fibrosis mice, the HSA-BMP7 administration significantly decreased the hepatic fibrosis area and the level of hydroxyproline. Based on these results, it appears that HSA-BMP7 has the potential for serving as a therapeutic agent for the treatment of liver fibrosis.

The yeast strain Saccharomyces cerevisiae is an eukaryotic organism that has been widely used for the production of fermented foods. Most cells secrete extracellular vesicles (EVs), small particles composed of lipid membranes. Elucidating the role of EVs as a new intercellular communication system and developing novel EV-based therapies have attracted the increased attention of researchers. Although recent studies have reported the secretion of EVs from S. cerevisiae, their in vivo fate and subsequent EV-mediated biological responses in the host are unclear. In this study, we characterized both the biodistribution of locally (intradermally and subcutaneously) administered Saccharomyces cerevisiae-derived EVs (S-EVs) and the EV-mediated immune responses to evaluate their potential use as biocompatible vaccine adjuvants. S-EVs were round but heterogeneous in size and contained glucan, DNA, and RNA. Their mean particle sizes and zeta potentials were approximately 177.5 nm and −14.6 mV, respectively. We provided evidence that locally administered S-EVs were delivered to the lymph nodes, mainly reaching the B-cell zone. Measurement of host immune reactions revealed that administration of S-EVs increased the expression of cytokine (tumor necrosis factor (TNF)-α) and costimulatory molecules (CD40, CD80, CD86), which are indicators of immune activation. Especially, subcutaneously injected S-EVs showed potent adjuvanticity, indicating that subcutaneous administration of S-EVs is the desirable approach for achieving effective immune stimulation. These findings will facilitate the development of novel EV-based immunotherapies.

Osteoporosis is treated with oral and parenteral bone resorption inhibitors such as bisphosphonates, and parenteral osteogenic drugs including parathyroid hormone (PTH) analogues and anti-sclerostin antibodies. In the present study, we synthesized KY-054, a 4,6-substituted coumarin derivative, and found that it potently promoted osteoblast differentiation with an increase in alkaline phosphatase (ALP) activity at 0.01–1 µM in mouse-derived mesenchymal stem cells (ST2 cells) and rat bone marrow-derived mesenchymal stem cells (BMSCs). In the ovariectomized (OVX) rats, KY-054 (10 mg/kg/d, 8 weeks) increased plasma bone-type ALP activity, suggesting in vivo promoting effects on osteoblast differentiation and/or activation. In dual-energy X-ray absorption (DEXA) scanning, KY-054 significantly increased the distal and diaphyseal femurs areal bone mineral density (aBMD) that was decreased by ovariectomy, indicating its beneficial effects on bone mineral contents (BMC) and/or bone volume (BV). In micro-computed tomography (micro-CT) scanning, KY-054 had no effect on metaphysis trabecular bone loss and microarchitecture parameters weakened by ovariectomy, but instead increased metaphysis and diaphysis cortical bone volume (Ct.BV) and cortical BMC (Ct.BMC) without reducing medullary volume (Med.V), resulting in increased bone strength parameters. It is concluded that KY-054 preferentially promotes metaphysis and diaphysis cortical bone osteogenesis with little effect on metaphysis trabecular bone resorption, and is a potential orally active osteogenic anti-osteoporosis drug candidate.

Since three-dimensional (3D)-printed tablets were approved by the United States Food and Drug Administration (FDA), 3D printing technology has garnered increasing interest for the fabrication of medical and pharmaceutical devices. With various dosing devices being designed for manufacture by 3D printing, 3D-printed ophthalmic formulations to release drugs have been one such target of investigation. In the current study, 3D-printed contact lenses designed for the controlled release of the antibiotic azithromycin were produced by vat photopolymerization, and the effect of the printer ink composition and a second curing process was investigated. The azithromycin-loaded contact lenses were composed of the cross-linking reagent polyethylene glycol diacrylate (PEGDA), PEG 400 as a solvent, a photoinitiator, and azithromycin. The 3D-printed contact lenses were fabricated successfully, and formulations with lower PEGDA concentrations produced thicker lenses. The mechanical strength of the PEGDA-based contact lenses was dependent on the amount of PEGDA and was improved by a second curing process. Drug release from 3D-printed contact lenses was reduced in the samples with a second curing process. The azithromycin-loaded contact lenses exhibited antimicrobial effects in vitro for both Gram-positive and -negative bacteria. These results suggest that 3D-printed contact lenses containing antibiotics are an effective model for treating eye infections by controlling drug release.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by inflammation and the destruction of bone and cartilage in affected joints. One of the unmet medical needs in the treatment of RA is to effectively prevent the structural destruction of joints, especially bone, which progresses because of resistance to conventional drugs that mainly have anti-inflammatory effects, and directly leads to a decline in the QOL of patients. We previously developed a novel and orally available type II kinase inhibitor of colony-stimulating factor-1 receptor (CSF1R), JTE-952. CSF1R is specifically expressed by monocytic-lineage cells, including bone-resorbing osteoclasts, and is important for promoting the differentiation and proliferation of osteoclasts. In the present study, we investigated the therapeutic effect of JTE-952 on methotrexate (MTX)-refractory joint destruction in a clinically established adjuvant-induced arthritis rat model. JTE-952 did not suppress paw swelling under inflammatory conditions, but it inhibited the destruction of joint structural components including bone and cartilage in the inflamed joints. In addition, decreased range of joint motion and mechanical hyperalgesia after disease onset were suppressed by JTE-952. These results suggest that JTE-952 is expected to prevent the progression of the structural destruction of joints and its associated effects on joint motion and pain by inhibiting CSF1/CSF1R signaling in RA pathology, which is resistant to conventional disease-modifying anti-rheumatic drugs such as MTX.

Metallothionein (MT) 1 and 2 are ubiquitously expressed cysteine-rich, low molecular weight proteins. MT expression is upregulated in skeletal muscle during aging. MTs also play role in multiple types of skeletal muscle atrophy. Meanwhile, it has been reported that MT1 and MT2 gene deficiency increases myogenesis in MT knockout (MTKO) mice. However, little is known about the effect of MTs on muscle formation and atrophy. In this study, we investigated the effect of MT1 and MT2 gene knock-out using the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (CRISPR-Cas9) system in an in vitro skeletal muscle differentiation model (C2C12 cell line). MT deficiency promoted myogenic differentiation and myotube formation in C2C12 cells. Muscle-specific transcription factors MyoD and myogenin were found to be upregulated at the late stage of myotube differentiation in MTKO cells. Furthermore, the fast-twitch myosin heavy chain (MyHC) protein expression was similar in MTKO and mock-transfected myotubes, but slow-MyHC expression was higher in MTKO cells than in mock cells. The MT gene deletion did not affect the number of fast MyHC-positive myotubes but increased the number of slow MyHC-positive myotubes. Treatment with the antioxidant N-acetylcysteine (NAC) inhibited the increase in the number of slow MyHC-positive myotubes as well as slow-MyHC expression in MTKO cells. In contrast, NAC treatment did not alter the number of fast MyHC-positive myotubes or the expression of fast-MyHC in MTKO cells. These results suggest that the antioxidant effects of MTs may be involved in slow-twitch myofiber formation in skeletal muscle.

A shift towards obtaining emergency contraceptives without a prescription have been discussed in Japan. In response to this social background, we aimed at investigating the background of sexual intercourse, emergency contraceptive use, and knowledge of sexual and reproductive health education among women of reproductive age in Japan. In this study, we conducted a national wide cross-sectional questionnaire survey using a total of 4 web-based domains (background, sexual history, emergency contraceptives, and sexual and reproduction-related knowledge) composed of 50 questions. We obtained responses from a total of 4,631 participants of varying age groups (18–25, 26–35, and 36–45 years old) and 47 prefectures (84 to 118 from each prefecture). Among participant responses, 69.7% are sexually active, of which 49.0% had experiences of sexual intercourse with an unknown person. The responses from a total of 737 participants who have sexual intercourse, know of emergency contraceptives, and have experienced a situation that necessitated the use of emergency contraceptives, were analyzed. Of these participants, 46.4% (342/737) took emergency contraceptives, while 43.6% (321/737) participants did not take emergency contraceptives. Participants who have the knowledge for obtaining emergency contraceptives through the correct means were 52.6% (2438/4631). This study showed that approximately half of participants may not have correct knowledge of emergency contraceptives. In addition, approximately half of sexually active participants are facing unintended pregnancies due to a lack of sexual and reproductive awareness. Hence, comprehensive sex education is necessary to achieve social and regulatory changes centered on emergency contraceptives.

Recently, microneedling as a cosmetic product has attracted attention as one way to improve skin barrier function and moisturizing function to reduce wrinkle formation. However, some cases of erythema and edema have been reported as side effects. In order to develop safer microneedle cosmetics, we investigated whether microneedles can improve skin barrier function and moisturizing function even when applied in a non-invasive manner that does not penetrate the stratum corneum. We established the condition of non-penetrating microneedle application on reconstructed human full-thickness skin models and examined the effect on the skin models when microneedles were applied under this condition. Microneedle application increased the gene expression of serine palmitoyltransferase long chain base subunit (SPTLC) 3, filaggrin, and transglutaminase 1. The amount of ceramide produced by SPTLC was also increased by microneedle application. Gene expression of filaggrin-degrading enzymes and the amount of free amino acids, a product of filaggrin degradation, were also increased by microneedling. These results suggest that non-invasive microneedle application can improve skin barrier function and moisturizing function by increasing the amount of ceramide and natural moisturizing factors.

Ca_v3.2 channels belong to the T-type calcium channel (T-channel) family, i.e., low voltage-activated calcium channels, and are abundantly expressed in the nociceptors, playing a principal role in the development of pathological pain. The channel activity of Ca_v3.2 is suppressed by zinc under physiological conditions. We thus tested whether dietary zinc deficiency would cause Ca_v3.2-dependent nociceptive hypersensitivity in mice. In the mice fed with zinc deficient diet for 2 weeks, plasma zinc levels declined by more than half, and mechanical allodynia developed. The dietary zinc deficiency-induced allodynia was restored by T-channel inhibitors or by Ca_v3.2 gene silencing. These data demonstrate that zinc deficiency induces Ca_v3.2-dependent nociceptive hypersensitivity in mice, thereby suggesting that pain experienced by patients with diseases accompanied by zinc deficiency (e.g., chronic kidney disease) might involve the increased Ca_v3.2 activity.

Bortezomib, an anticancer drug for multiple myeloma and mantle cell lymphoma, causes severe adverse events and leads to peripheral neuropathy. The associated neuropathy limits the use of bortezomib and could lead to discontinuation of the treatment; therefore, effective intervention is crucial. In the present study, we statistically searched for a drug that could alleviate bortezomib-induced peripheral neuropathy using adverse event self-reports. We observed that specific inhibitors of the mechanistic target of rapamycin (mTOR) lowered the incidence of bortezomib-induced peripheral neuropathy. These findings were experimentally validated in mice, which exhibited long-lasting mechanical hypersensitivity after repeated bortezomib treatment. This effect was inhibited for hours after a systemic injection with rapamycin or everolimus in a dose-dependent manner. Bortezomib-induced allodynia was accompanied by the activation of spinal astrocytes, and intrathecal injection of mTOR inhibitors or an inhibitor of ribosomal protein S6 kinase 1, a downstream target of mTOR, exhibited considerable analgesic effects in a dose-dependent manner. These results suggest that mTOR inhibitors, which are readily available to patients prescribed bortezomib, are one of the most effective therapeutics for bortezomib-induced peripheral neuropathy.

Pazopanib is one of recommended treatment for metastatic renal cell carcinoma (RCC). Despite its effectiveness, patients often difficult to continue pazopanib treatment due to adverse events (AEs). We established an ambulatory care pharmacy practice that enables pharmacist–urologist collaboration to manage patients with RCC. This study evaluated the usefulness of this collaborative management. We retrospectively reviewed the medical records of 51 consecutive patients with metastatic RCC receiving pazopanib at the Kobe City Medical Center General Hospital between April 2014 and December 2020. Our collaborative management was implemented in October 2016. The time to pazopanib discontinuation was compared between patients who started pazopanib before (n = 30) and after (n = 21) the implementation of the collaborative management. A multivariate Cox regression analysis was performed to analyze the factors associated with pazopanib discontinuation. In the collaborative management, the oncology pharmacists had a total of 245 face-to-face patient consultations, and provided 286 suggestions [according to supportive care in pazopanib treatment (214 suggestions) were most frequent], and 236 (82.5%) were accepted by urologists. The median time to discontinuation (6.1 months vs. 2.4 months, p = 0.024) was significantly longer in the after group. Multivariate analysis showed that collaborative management (hazard ratio (HR) 0.49, 95% confidence interval (CI) 0.26–0.88, p = 0.017), and Eastern Cooperative Oncology Group performance status (ECOG PS) ≥2 at pazopanib initiation (HR 3.87, 95% CI 1.47–9.13, p = 0.008) were significantly associated with pazopanib discontinuation. These results suggested that, compared to conventional management, collaborative management is effective at prolonging the time to pazopanib discontinuation.

Since small extracellular vesicle (sEVs) are involved in cell-to-cell communication via transfer of certain bioactive molecules and have the capability to overcome biological barriers against drug transport, their use as a drug delivery system (DDS) has been demonstrated in treatment of a diverse range of diseases. However, some issues in drug encapsulation have been pointed out, including low encapsulation efficiency and poor reproducibility. It was previously reported that liposomes containing phosphatidylserine (PS) can fuse together in the presence of calcium ion, which allows for drug encapsulation into the resultant liposomes (i.e., calcium fusion method). On the other hand, PS is reportedly present in lipid membrane of sEVs as a distinct lipid composition. We therefore hypothesized that PS-mediated membrane fusion of sEVs with PS-liposomes encapsulating therapeutic agents via the calcium fusion method can be applied to convenient drug encapsulation into sEVs. Membrane fusion of PS-liposomes and sEVs derived from murine melanoma B16F1 cells (B16-sEVs) was firstly confirmed. The obtained nanoparticles, termed chimeric nanoparticles (CM-NP), showed comparable cellular uptake to B16-sEVs into B16F1 cells. Moreover, CM-NP encapsulating an anticancer drug doxorubicin (DOX) (CM-NP-DOX) could be prepared by membrane fusion of PS-liposomes encapsulating DOX (PS-Lipo-DOX) and B16-sEVs. CM-NP-DOX exhibited a superior anticancer effect on B16F1 cells in vitro compared with PS-Lipo-DOX. These findings suggest that the calcium fusion method could be applied for membrane fusion of sEVs and PS-liposomes, and that this approach would likely be useful for efficient drug encapsulation into sEVs, as well as increasing liposome functionality.

The anticancer drug oxaliplatin is associated with peripheral neuropathy as a side effect accompanied by mechanical and cold allodynia. Although the superficial layer of the spinal cord dorsal horn is known to receive information primarily from peripheral pain nerves, to our knowledge, no in vivo electrophysiological analyses have been conducted to determine whether oxaliplatin administration increases the excitability of superficial layer neurons. Therefore, in vivo extracellular recordings were performed to measure action potentials in the deep and superficial layers of the spinal cord dorsal horn in rats treated with a single dose (6 mg/kg) of oxaliplatin. Action potentials were produced by mechanical stimulation with von Frey filaments to the hindlimb receptive fields. The results revealed that the firing frequency of action potentials increased relative to the intensity of mechanical stimulation, and that both deep and superficial layer neurons in the spinal cord dorsal horn increased significantly in oxaliplatin-treated compared with vehicle-treated rats, especially in the superficial layer. Several superficial layer neurons showed spontaneous firing that was not seen in vehicle-treated rats. In addition, a clear increase was seen in the firing frequency of neurons in the superficial layer of oxaliplatin-treated rats in response to a cold stimulus (here, the addition of acetone to the hindlimb receptive field). This study suggests that the superficial spinal cord dorsal horn strongly reflects the pain pathophysiology in peripheral neuropathy induced by oxaliplatin administration, and that the superficial layer neurons are useful for in vivo electrophysiological analysis using this pathological model.

Tramadol is metabolized by CYP2D6 to an active metabolite, which in turn acts as an analgesic. This study aimed to investigate the impact of CYP2D6 genotype on the analgesic effect of tramadol in clinical practice. A retrospective cohort study was performed in patients treated with tramadol for postoperative pain after arthroscopic surgery for rotator cuff injury during April 2017–March 2019. The impact of CYP2D6 genotypes on the analgesic effects was assessed by the numeric rating scale (NRS) pain scoring and analyzed by the Mann–Whitney U test. Stepwise multiple linear regression analysis was performed to identify predictive factors for the area under the time-NRS curve (NRS-AUC), which was calculated using the linear trapezoidal method. Among the 85 enrolled Japanese patients, the number of phenotypes with CYP2D6 normal metabolizer (NM) and intermediate metabolizer (IM) was n = 69 (81.1%) and n = 16 (18.9%), respectively. The NRS and NRS-AUC in the IM group were significantly higher than those in the NM group until Day 7 (p < 0.05). The multiple linear regression analysis indicated that the CYP2D6 polymorphism was a prediction factor of the high NRS-AUC levels in Days 0–7 (β = 9.52, 95% CI 1.30–17.7). In IM patients, the analgesic effect of tramadol was significantly reduced one week after orthopedic surgery in clinical practice. Therefore, dose escalation of tramadol or the use of alternative analgesic medications can be recommended for IM patients.

Transient receptor potential (TRP) channels play a significant role in taste perception. TRP ankyrin 1 (TRPA1) is present in the afferent sensory neurons and is activated by food-derived ingredients, such as Japanese horseradish, cinnamon, and garlic. The present study aimed to investigate the expression of TRPA1 in taste buds, and determine its functional roles in taste perception using TRPA1-deficient mice. In circumvallate papillae, TRPA1 immunoreactivity colocalised with P2X2 receptor-positive taste nerves but not with type II or III taste cell markers. Behavioural studies showed that TRPA1 deficiency significantly reduced sensitivity to sweet and umami tastes, but not to salty, bitter, and sour tastes, compared to that in wild-type animals. Furthermore, administration of the TRPA1 antagonist HC030031 significantly decreased taste preference to sucrose solution compared to that in the vehicle-treated group in the two-bottle preference tests. TRPA1 deficiency did not affect the structure of circumvallate papillae or the expression of type II or III taste cell and taste nerve markers. Adenosine 5′-O-(3-thio)triphosphate evoked inward currents did not differ between P2X2- and P2X2/TRPA1-expressing human embryonic kidney 293T cells. TRPA1-deficient mice had significantly decreased c-fos expression in the nucleus of the solitary tract in the brain stem following sucrose stimulation than wild-type mice. Taken together, the current study suggested that TRPA1 in the taste nerve contributes to the sense of sweet taste in mice.