Published papers

Objectives: Salivary Immunoglobulin A (IgA) plays a crucial role in mucosal immunity. However, the mechanisms that regulate its production are unclear. Spermidine (SPD), a polyamine involved in various cellular functions, has been implicated in immune modulation. In this study, we investigated the presence of SPD in rat salivary glands and its potential role in enhancing production of IgA. Methods: Male Wistar rats were fed a low-polyamine diet for eight weeks. Submandibular and parotid glands were harvested and metabolomic analysis was used to determine the SPD concentration, reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to evaluate gene expression related to polyamine metabolism and autophagy, enzyme-linked immunosorbent assay (ELISA) was used to quantify secretion of IgA, and immunohistochemistry was used to localize spermidine synthase (SRM). Results: Metabolomic analysis revealed that the concentration of SPD was significantly higher in the submandibular gland than in the parotid gland. RT-qPCR revealed higher SRM and LC3b mRNA expression, and lower Rubicon expression in the submandibular gland. Ex vivo SPD supplementation significantly increased secretion of IgA from both glands. Immunohistochemistry confirmed strong SRM expression in the acinar and ductal cells of the submandibular gland. Conclusions: These findings suggest that SPD is endogenously synthesized in rat salivary glands, particularly in the submandibular gland, and may enhance the ex vivo production capacity of IgA in salivary gland tissues. These results provide insights into the role of polyamines in mucosal immunity and suggest potential therapeutic applications of SPD in enhancing oral immune defense.

Background/Objectives: The objective of this study was to investigate the metabolomic profiles of patients with colorectal cancer (CRC) across various stages of the disease. Methods: The plasma samples were obtained from 255 subjects, including patients with CRC in stages I-IV, polyps, and controls. We employed capillary electrophoresis time-of-flight mass spectrometry and liquid chromatography triple quadrupole mass spectrometry to analyze hydrophilic metabolites comprehensively. The data were randomly divided into two groups, and consistent differences observed in both groups were analyzed. Results: Acetylated polyamines, such as N1-acetylspermine and N1, N12-diacetylspermine, consistently showed elevated concentrations in stage IV compared to stages I-III. Non-acetylated polyamines, including spermine and spermidine, exhibited increasing trends from polyp to stage IV. Other metabolites, such as histidine and o-acetylcarnitine, showed decreasing trends across stages. While acetylated polyamines have been reported as CRC detection markers, our findings suggest that they also possess diagnostic potential for distinguishing stage IV from other stages. Conclusions: This study showed stage-specific changes in metabolic profiles, including polyamines, of colorectal cancer.

The Tsuruoka Metabolomics Cohort Study (TMCS) is an ongoing population-based cohort study being conducted in the rural area of Yamagata Prefecture, Japan. This study aimed to enhance the precision prevention of multi-factorial, complex diseases, including non-communicable and aging-associated diseases, by improving risk stratification and prediction measures. At baseline, 11,002 participants aged 35–74 years were recruited in Tsuruoka City, Yamagata Prefecture, Japan, between 2012 and 2015, with an ongoing follow-up survey. Participants underwent various measurements, examinations, tests, and questionnaires on their health, lifestyle, and social factors. This study uses an integrative approach with deep molecular profiling to identify potential biomarkers linked to phenotypes that underpin disease pathophysiology and provide better mechanistic insights into social health determinants. The TMCS incorporates multi-omics data, including genetic and metabolomic analyses of 10,933 participants, and comprehensive data collection ranging from physical, psychological, behavioral, and social to biological data. The metabolome is used as a phenotypic probe because it is sensitive to changes in physiological and external conditions. The TMCS focuses on collecting outcomes for cardiovascular disease, cancer incidence and mortality, disability and functional decline due to aging and disease sequelae, and the variation in health status within the body represented by omics analysis that lies between exposure and disease. It contains several sub-studies on aging, heated tobacco products, and women’s health. This study is notable for its robust design, high participation rate (89%), and long-term repeated surveys. Moreover, it contributes to precision prevention in Japan and East Asia as a well-established multi-omics platform.

Introduction: As the high mortality rate of gastric cancer (GC) is due to delayed diagnosis, early detection is vital for improved patient outcomes. Metabolic deregulation plays an important role in GC. Although various metabolite-level biomarkers for early detection have been assessed, there is still no unified early detection method. We conducted a plasma metabolome study to assess metabolites that may distinguish GC samples from non-GC samples. Methods: Blood samples were collected from 72 GC patients and 29 control participants (non-GC group) at the Tokyo Medical University Hospital between March 2020 and November 2020. Hydrophilic metabolites were identified and quantified using liquid chromatography-time-of-flight mass spectrometry. Differences in metabolite concentrations between the GC and non-GC groups were evaluated using the Mann-Whitney test. The discrimination ability of each metabolite was evaluated by the area under the receiver operating characteristic curve. A radial basis function (RBF) kernel-based support vector machine (SVM) model was developed to assess the discrimination ability of multiple metabolites. The selection of variables used for the SVM utilized a step-wise regression method. Results: Of the 96 quantified metabolites, 8 were significantly different between the GC and non-GC groups. Of these, N1-acetylspermine, succinate, and histidine were used in the RBF-SVM model to discriminate GC samples from non-GC samples. The area under the curve (AUC) of the RBF-SVM model was higher (0.915; 95% CI: 0.865-0.965, p < 0.0001), indicating good performance of the RBF-SVM model. The application of this RBF-SVM to the validation dataset resulted from the AUC of the RBF-SVM model was (0.885; 95% CI: 0.797-0.973, p < 0.0001), indicating the good performance of the RBF-SVM model. The sensitivity of the RBF-SVM model was better (69.0%) than those of the common tumor markers carcinoembryonic antigen (CEA) (10.5%) and carbohydrate antigen 19-9 (CA19-9) (2.86%). The RBF-SVM showed a low correlation with CEA and CA19-9, indicating its independence. Conclusion: We analyzed plasma metabolomics, and a combination of the quantified metabolites showed high sensitivity for the detection of GC. The independence of the RBF-SVM from tumor markers suggested that their complementary use would be helpful for GC screening.

Epithelial–mesenchymal transition (EMT)—a fundamental process in embryogenesis and wound healing—promotes tumor metastasis and resistance to chemotherapy. While studies have identified signaling components and transcriptional factors responsible in the TGF-β-dependent EMT, whether and how intracellular metabolism is integrated with EMT remains to be fully elucidated. Here, we showed that TGF-β induces reprogramming of intracellular amino acid metabolism, which is necessary to promote EMT in non-small cell lung cancer cells. Combined metabolome and transcriptome analysis identified prolyl 4-hydroxylase α3 (P4HA3), an enzyme implicated in cancer metabolism, to be upregulated during TGF-β stimulation. Further, knockdown of P4HA3 diminished TGF-β-dependent changes in amino acids, EMT, and tumor metastasis. Conversely, manipulation of extracellular amino acids induced EMT-like responses without TGF-β stimulation. These results suggest a previously unappreciated requirement for the reprogramming of amino acid metabolism via P4HA3 for TGF-β-dependent EMT and implicate a P4HA3 inhibitor as a potential therapeutic agent for cancer.

N1‐methyladenosine (m1A) modification widely participates in the occurrence and progression of numerous diseases. Nevertheless, the potential roles of m1A in the tumor immune mi-croenvironment (TIME) are still not fully understood. Based on 10 m1A methylation regulators, we comprehensively explored the m1A modification patterns in 502 patients with oral squamous cell carcinoma (OSCC). The m1A modification patterns were correlated with TIME characteristics and the m1A score was established to evaluate the effect of the m1A modification patterns on individual OSCC patients. The TIME characteristics and survival outcomes under the three m1A modification patterns were significantly distinct. OSCC patients in the high m1A score group were characterized by poorer prognosis, lower immune infiltration, lower ssGSEA score, lower expression levels of immune checkpoint molecules, and higher tumor mutation loads. The present study revealed that m1A modification might be associated with the TIME in OSCC, and has potential predictive ability for the prognosis of OSCC.

Background: Postoperative delirium (POD) is a severe complication associated with various adverse outcomes, especially in older patients. Although the incidence and risk factors for POD have been explored in general surgery, they have not been fully elucidated. Early identification of high-risk patients and active preoperative intervention are considered essential for the prevention of POD. Recently, psychiatric consultation intervention have been shown to prevent delirium. This study investigated the effect of preoperative psychiatric interventions on preventing POD in our specific surgical context. Materials and Methods: This retrospective, single-center observational study included 86 patients who underwent major oral and maxillofacial surgery with free flap reconstruction between 2016 and 2023. The effect of psychiatric intervention were compared between patients with and without delirium. Results: Preoperative psychiatric intervention did not reduce the incidence of POD. The incidence of POD was 29.1 %. Univariate analyses showed no significant associations between POD and any clinical variables. Conclusion: There was no difference in the incidence of POD between patients who received preoperative psychiatric intervention and those who did not, and further investigation is needed to determine the efficacy of preoperative psychiatric intervention in the prevention of POD.

Disorders pertaining to 5-methylcytosine (m5C) modifications are involved in the pathological process of many diseases. However, the effect of m5C on the tumorigenesis and progression of oral squamous cell carcinoma (OSCC) remains unclear. In this study, we integrated the genomic and clinical data of 558 OSCC samples to comprehensively evaluate m5C modification patterns. Based on 16 m5C methylation regulators, two m5C modification clusters were identified with distinct tumor immune microenvironment (TIME) characteristics and prognosis in OSCC. We then performed weighted gene co-expression network analysis (WGCNA) to identify m5C modification cluster-related modules. Genes in the selected module were chosen to construct the m5Cscore scoring system for evaluating m5C modification pattern in individual OSCC patients. Patients with a high m5Cscore had higher immune, stromal, and ESTIMATE scores; lower tumor purity score; lower immune activity; and higher tumor mutational burden. The overall survival rate and progression-free survival rate were markedly worse and the tumor recurrence rate was higher in OSCC patients with a high m5Cscore. Furthermore, patients with oral leukoplakia who also had a high m5Cscore had a higher risk of deterioration to OSCC. This study demonstrated that m5C modification patterns might affect the TIME in OSCC. m5Cscore may provide a new approach for predicting the prognosis and progression of OSCC.

Oral mucositis (OM) is one of the most frequently observed adverse oral events in radiation therapy for patients with head and neck cancer. Thus, objective evaluation of OM severity is needed for early and timely intervention. Here, we analyzed the time-course of salivary metabolomic profiles during the radiation therapy. The severity of OM (National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events v3.0) of nine patients with head and neck cancer was evaluated. Partial least squares regression-discriminant analysis, using samples collected before radiation therapy, showed that histidine and tyrosine highly discriminated high-grade OM from low-grade OM before the start of radiation therapy (significant difference, p = 0.048 for both metabolites). Further, the pretreatment concentrations of gamma-aminobutyric acid and 2-aminobutyric acids were higher in the high-grade OM group. Although further validations are still necessary, this study showed potentially associated metabolites with worse radiotherapy-related OM among patients with head and neck cancer.

Background/Objectives: Sepsis is a life-threatening condition characterized by organ dysfunction due to a dysregulated host response to infection. Mitochondrial dysfunction is considered a key contributor to the pathogenesis of sepsis, but its molecular mechanisms remain unclear. Methods: In this study, we used a cecal ligation and puncture (CLP) model to induce sepsis in wild-type (WT) and cyclophilin D knockout (CypD KO) mice. Liver tissues were collected at 0, 6, and 18 h post-CLP and analyzed using liquid chromatography–tandem mass spectrometry (LC-MS/MS). Results: Metabolomic profiling revealed that lactate levels significantly increased in the WT mice but remained stable in the KO mice. While AMP levels were preserved in the KO mice, these mice had significantly higher glutathione disulfide (GSSG) and spermidine concentrations than the WT mice at 18 h (p < 0.05). The levels of malondialdehyde (MDA), a marker of oxidative stress, were also significantly lower in the KO mice at 18 h (p < 0.05). These findings suggest that CypD deficiency preserves mitochondrial function, enhances resistance to oxidative stress, and mitigates septic liver injury. Conclusions: Our results highlight the potential of targeting mitochondrial permeability transition as a therapeutic strategy for sepsis.

Objective: We investigated the metabolic changes in pancreatic ductal adenocarcinoma to identify the mechanisms of treatment response of neoadjuvant chemoradiation therapy. Methods: Frozen tumor and non-neoplastic pancreas tissues were prospectively obtained from 88 patients with pancreatic ductal adenocarcinoma who underwent curative-intent surgery. Sixty-two patients received neoadjuvant chemoradiation therapy and 26 patients did not receive neoadjuvant therapy (control group). Comprehensive analysis of metabolites in tumor and non-neoplastic pancreatic tissue was performed by capillary electrophoresis-mass spectrometry. Results: Capillary electrophoresis-mass spectrometry detected 90 metabolites for analysis among more than 500 ionic metabolites quantified. There were significant differences in 27 tumor metabolites between the neoadjuvant chemoradiation therapy and control groups. There were significant differences in eight metabolites [1-MethylnNicotinamide, Carnitine, Glucose, Glutathione (red), N-acetylglucosamine 6-phosphate, N-acetylglucosamine 1-phosphate, UMP, Phosphocholine] between good responder and poor responder for neoadjuvant chemoradiation therapy. Among these metabolites, phosphocholine, Carnitine and Glutathione were associated with recurrence-free survival only in the neoadjuvant chemoradiation therapy group. Microarray confirmed marked gene suppression of choline transporters [CTL1-4 (SLC44A1-44A4)] in pancreatic ductal adenocarcinoma tissue of neoadjuvant chemoradiation therapy group. Conclusion: The present study identifies several important metabolic consequences and potential neoadjuvant chemoradiation therapy targets in pancreatic ductal adenocarcinoma. Choline metabolism is one of the key pathways involved in recurrence of the patients with pancreatic ductal adenocarcinoma who received neoadjuvant chemoradiation therapy.

Background/Aim: Treatment-related bladder toxicities are a primary concern in the management of prostate cancer radiotherapy. This study aimed to identify urinary metabolites that can predict early radiation cystitis-related toxicities in patients undergoing radiotherapy for prostate cancer. Patients and Methods: Patients’ clinical characteristics and urine samples were collected before, two weeks after, at the end, and three months after the initiation of radiotherapy and subsequently analyzed. Capillary electrophoresis- mass spectrometry and liquid chromatography-mass spectrometry were used for comprehensive quantification of urinary metabolites. Multivariate analysis was conducted to identify potential protective factors against the early toxicities of radiation cystitis. Results: A total of 176 samples were obtained from 44 patients. Betaine, tartrate, N,N-dimethylglycine, and homocarnosine were identified as independent protective factors against early toxicities of radiation cystitis among various potential confounding metabolic factors. Comorbid diabetes mellitus was also identified as a protective factor. Conclusion: Betaine, tartrate, N,N-dimethylglycine, and homocarnosine were identified as protective urinary metabolites against early radiation cystitis. Urinary metabolomic profiling may be a useful tool for investigating disease metabolism in metabolic disorders and cancers. Its ease of use and repeatability make it an optimal method for patient follow-up.

This study aimed to validate and reanalyze urinary biomarkers for detecting colorectal cancers (CRCs). We previously conducted urinary metabolomic analyses using capillary electro-phoresis-mass spectrometry and found a significant difference in various metabolites, especially polyamines, between patients with CRC and healthy controls (HC). We analyzed additional samples and confirmed consistency between the newly and previously analyzed data. In total, we included 36 HC, 34 adenoma (AD), and 214 CRC samples, which were used for subsequent analyses. Among the 132 quantified metabolites, 16 exhibited consistent differences in both datasets, which included polyamines, etc. Pathway analyses of the integrated data revealed significant differences in many metabolites, such as glutamine, and metabolites of the TCA and urea cycles. The discrimination ability of the combination of multiple metabolites among the three groups was evaluated, which yielded higher sensitivity than tumor markers. The Mann–Whitney test was employed to evaluate the prognosis predictivity of the assessed metabolites and the difference between the patients with or without recurrence, which yielded 16 significantly different metabolites. Among these 16 metabolites, 11 presented significant prognosis predictivity. These data indicated the potential of metabolite-based discrimination of patients with CRC and AD from HC and prognosis predic-tivity of the monitored metabolites.

Background: Massage and aromatherapy are frequently used by older adults as alternative interventions to enhance immunity and induce relaxation. This pilot study evaluated the effect of massage therapy with oil and aromatherapy alone and in combination using objective biological indices. Methods: Twenty-eight participants recruited by convenience sampling included adults aged between 25 and 65 years (Group 1), elderly individuals over 65 years without nursing care (Group 2), and older adults over 65 needing long-term nursing support (Group 3). A multiple-group pretest-post-test design was employed, and the effect among the three groups was compared. Interventions included: (i) oil massage therapy; (ii) aromatherapy; and (iii) aroma oil massage therapy. Each therapy session lasted 5 min, with 3 min of observation before and after the session and 10 min interval between sessions. Group 3 omitted one therapy (2: aromatherapy) to reduce their physical burden. An electroencephalogram (EEG) was recorded for α, β, and θ activities of brain waves. EEG data were collected at three points: before, during, and after each treatment. Salivary secretory immunoglobulin A (s-IgA) concentration, oxygen saturation (SPO2), and pulse rate were measured before and after each session. Results: Across all therapy modalities, there was a noticeable increase in the α wave, indicative of relaxation, during the treatment. Significant differences were observed before and during the oil massage in both Group 1 and Group 2. Aromatherapy demonstrated a significant difference before and during treatment in Group 1. Among the biological parameters, s-IgA levels indicated no significant changes. The pulse rate decreased with oil massage. Significant differences were noted before and after therapy in all cases for SPO2 and in Group 2 for pulse rate. Conclusions: Three therapies induced EEG and physiological changes in the adult group and older adults without nursing care. However, these effects are limited in older adults requiring nursing care.

Background/Aim: Underwater exercise is aimed at preventing aging, maintaining, and improving motor function, and improving physical function. However, its rehabilitation effects have not been well evaluated. In order to gain insight into the molecular basis of its rehabilitation effects, possible changes in the salivary metabolites of four older persons with disability (mean age: 72.5 years) during underwater exercise were investigated. Materials and Methods: Halitosis was measured by Breathtron; salivary bacterial number by bacterial counter; amino acids by amino acid analyzer; 8-oxoguanine by ELISA; and intracellular metabolites by capillary electrophoresis, time-of-flight mass spectrometry, liquid chromatography, and triode quadrupole mass spectrometry. Results: Underwater exercise induced apparent declines in two major salivary amino acids (glycine and proline) and bacterial numbers in the cheek mucosa and salivary, without apparent changes in the halitosis and urine 8-oxoguanine concentration. Older subjects showed higher concentrations of most of 166 metabolites compared to young volunteers (mean age: 38.8 years old). Fifteen compounds were significantly reduced with the progression of underwater exercise. Conclusion: Improvement of upright balance function with underwater exercise is correlated with several salivary components.

Symptoms of oral discomfort such as dry mouth are common in older people wearing dentures. Such symptoms are mainly treated symptomatically. Many of these symptoms are related to saliva, and associations with salivary volume have been reported. Although denture treatment improves symptoms by increasing the amount of saliva, the effects on salivary components remain unclear. This study aimed to investigate the effects of denture treatment on salivary metabolite changes based on salivary metabolome analyses. We enrolled 21 patients requiring denture treatment. At the first visit, and after completion of denture treatment, saliva outflow was measured under resting and stimulated conditions, samples for salivary metabolite analysis were collected, and masticatory efficiency was tested. In all participants, masticatory efficiency increased after denture treatment. Moreover, the amounts of resting and stimulated saliva were increased. Using salivary metabolome analysis, 61 salivary metabolites were detected. Substantial concentration changes were observed for 4 and 21 metabolites in resting and stimulated saliva, respectively. The four metabolites common to both saliva tests had significantly lower concentrations after treatment. These results suggest that the improvement in masticatory function by dentures is related not only to salivary secretion volume, but also to salivary metabolite composition.

Acute coronary syndrome (ACS) is a life-threatening condition that requires a prompt diagnosis and therapeutic intervention. Although serum troponin I and creatinine kinase-MB (CK-MB) are established biomarkers for ACS, reaching diagnostic values for ACS may take several hours. In this study, we attempted to explore novel biomarkers for ACS with higher sensitivity than that of troponin I and CK-MB. The metabolomic profiles of 18 patients with ACS upon hospital arrival and those of the age-matched control (HC) group of 24 healthy volunteers were analyzed using liquid chromatography time-of-flight mass spectrometry. Volcano plots showed 24 metabolites whose concentrations differed significantly between the ACS and HC groups. Using these data, we developed a multiple logistic regression model for the ACS diagnosis, in which lysine, isocitrate, and tryptophan were selected as minimum-independent metabolites. The area under the receiver operating characteristic curve value for discriminating ACS from HC was 1.00 (95% confidence interval [CI]: 1.00–1.00). In contrast, those for troponin I and CK-MB were 0.917 (95% confidence interval [CI]: 0.812–1.00) and 0.988 (95% CI: 0.966–1.00), respectively. This study showed the potential for combining three plasma metabolites to discriminate ACS from HC with a higher sensitivity than troponin I and CK-MB.

Aim: This study aims to investigate eye tracking in the practical training of incontinence pad change, which is commonly required in older adult nursing. Background: Some competencies possessed by skilled and experienced personnel are difficult to verbalize into textbooks. However, this is crucial for education, especially nursing practice education. Eye-gaze analysis is one such tool that can aid the efficient transfer of knowledge to students. Therefore, eye-gaze analysis, a novel technology for visualizing situational awareness and decision-making, has recently gained traction in healthcare. Design: An observation study Methods: Ten nursing faculty members and 13 nursing students with prior incontinence pad change experience participated in this study using an older adult simulator. There were two groups of students – S1 with more recent experience in older adult care and incontinence pad changing and S2 with less. Areas of interest (AOIs) during incontinence pad preparation and fitting were determined based on gaze fixation and the time spent fixating on these areas was compared. Results: Students took longer than nursing faculty members. When visualizing the eye movements between the AOIs in the network, the faculty nurses and S1 alternated their gaze between the new incontinence pad and the buttocks and between other AOIs. Simultaneously, S2 tended to gaze or stare only at the new incontinence pad. Conclusion: The presented data may help interpret visual-based situational awareness and establish effective nursing education, especially in acquiring skills that are difficult to verbalize.

AbstractObjectivesTo synthesize how eye-tracking technology has been applied in nursing simulation and identify its contributions to educational design, learner assessment, and skill development.DesignA scoping review following the Arksey and O’Malley framework and PRISMA-ScR guidelines.Data sourcesPubMed, EBSCOhost, Scopus, and Web of Science were searched (September 2025), supplemented by manual screening.Review methodsEligible studies involved nursing participants, used eye-tracking as a primary method, and were conducted in simulation-based learning settings.ResultsFourteen studies met the inclusion criteria. Three themes emerged: (1) expert-novice gaze pattern differences, showing broader AOI coverage and more efficient scanning among experts; (2) cognitive-load indicators such as pupil dilation and fixation duration that varied by task complexity and experience; and (3) gaze-based feedback that enhanced reflective learning using visualizations, including heatmaps and gaze replays.ConclusionsEye-tracking provides objective insight into learners’ cognitive processes, supporting improved simulation design, assessment of clinical judgment and situational awareness, and the extraction of teachable visual-scanning strategies. Standardization and multimodal approaches are needed to advance future research.

Background: Nurses are responsible for comprehensively identifying patient conditions and associated environments. We hypothesize that gaze trajectories of nurses differ based on their experiences, even under the same situation. Methods: An eye-tracking device monitored the gaze trajectories of nurses with various levels of experience, and nursing students during the intravenous injection task on a human patient simulator. Results: The areas of interest (AOIs) were identified in the recorded movies, and the gaze durations of AOIs showed different patterns between experienced nurses and nursing students. A state transition diagram visualized the recognition errors of the students and the repeated confirmation of the vital signs of the patient simulator. Clustering analysis of gaze durations also indicated similarity among the participants with similar experiences. Conclusions: As expected, gaze trajectories differed among the participants. The developed gaze transition diagram visualized their differences and helped in interpreting their situational awareness based on visual perception. The demonstrated method can help in establishing an effective nursing education, particularly for learning the skills that are difficult to be verbalized.