Statin administration ameliorates ischemia-induced overactive bladder with improvement of blood flow and anti-inflammatory effects in rats.

AIMS: Statins are widely used to treat dyslipidemia and have been shown to reduce the risk of ischemic heart disease and cerebrovascular disease. The effects of statins on ischemia-induced overactive bladder (OAB) and the associated mechanisms were investigated in a rat model of chronic pelvic ischemia. METHODS: A pelvic ischemia model was created by iliac arterial injury (AI) and a high-fat diet using male Sprague-Dawley rats. Rats were assigned to 3 groups: control group, AI group, and AI + statin group. The control group underwent sham operation and was fed a normal diet. The AI group underwent AI surgery and was fed a high-cholesterol diet. The AI + statin group was administered a statin for 4 weeks. Cystometry was performed for 8 weeks after surgery. Blood flow was evaluated by laser meter. Thickness of the iliac arteries was measured, and microvascular density in the lamina propria was evaluated by immunostaining for CD31. Expressions of inflammatory cytokines in the bladder were measured by real-time PCR. RESULTS: Cystometry showed a significantly shorter voiding interval and lower bladder capacity in the AI group than in the control group. The AI + statin group showed improvement of these findings. The AI group showed decreased bladder blood flow, increased iliac arterial wall thickening, and decreased microvascular density compared to the control group. Statin administration improved blood flow. Iliac arterial wall thickening was suppressed, and microvascular density was increased by statin administration, though not significantly. Real-time PCR showed significantly higher expressions of inflammatory cytokines (IL-6, IL-8, and TNF-α) in the AI group than in the control group, and IL-6 and IL-8 expressions were lower in the AI + statin group than in the AI group. CONCLUSIONS: The present results suggest that statins are effective in OAB caused by arteriosclerosis and ischemia. The mechanism of their effects involves improved bladder blood flow and decreased bladder inflammation.

Prostate-specific antigen follow-up and management for patients undergoing holmium laser enucleation of the prostate.

OBJECTIVES: To investigate who needs a careful postoperative monitoring for prostate cancer (PCa) after holmium laser enucleation of the prostate (HoLEP). We examined characteristics and oncological outcomes of HoLEP-related PCa. METHODS: Patients who underwent HoLEP during 2002-2017 in a Japanese tertiary center were retrospectively analyzed. Patients were divided into non-PCa, PCa with HoLEP specimen (PCa-Ope), and PCa diagnosed during follow-up (PCa-Post). Outcomes of all HoLEP-related PCa were monitored. RESULTS: Of the total 758, 60 (7.9%) were diagnosed with PCa from resected specimen of HoLEP and 9 (1.2%) were diagnosed postoperatively. Preoperative prostate-specific antigen (iPSA), postoperative PSA (pPSA), and PSA density were significantly higher in both PCa groups than those in non-PCa group. While iPSA significantly correlated to prostate volume (PV), pPSA was not associated with PV. A receiver-operating-characteristics curve demonstrated that pPSA 1.2 ng/mL achieved the optimal cut-off (AUC 0.95) for the incidence of PCa-Post. In addition to the incidence of PCa and iPSA, lower enucleation efficiency (enucleated volume /PV) was significantly associated with pPSA >1.2 ng/mL. Among PCa-Ope, 51 were Grade Group (GG) ≤2 and 42 were followed-up with active surveillance, whereas 8 of 9 PCa-Post were GG ≥3 and 2 progressed to death. CONCLUSIONS: Patients undergoing HoLEP are associated with some risk of potential PCa. While oncological outcomes were favorable among PCa-Ope, postoperative PSA should be carefully monitored even if not diagnosed with PCa with HoLEP specimen. Enucleation efficiency should be also considered not to misread pPSA value.

Can displaced Anguilla marmorata return to their original habitat? Daily tracking study of their homing behavior.

Anguilla marmorata collected in the Odana River lower reaches were passive integrated transponder-tagged displaced and released into the upper river reaches (54 up-transported eels), and eels collected in the upper reaches were tagged and released downstream (52 down-transported eels). Their movements were detected once per day for 10 days using a portable radio-frequency identification (RFID) system. The homing rate of the down-transported eels was 38.9%, compared to 3.7% for the up-transported eels, suggesting that eels inhabiting upstream areas have relatively high fidelity to their habitats and downstream eels have less fidelity.

Ectopic endometriosis in the pelvic cavity evokes bladder hypersensitivity via transient receptor potential ankyrin 1 hyperexpression in rats.

INTRODUCTION AND HYPOTHESIS: In women with chronic pelvic pain (CPP), interstitial cystitis/bladder pain syndrome (IC/BPS) and endometriosis frequently coexist. The mechanism of these diseases coexisting is explained by cross-sensitization between endometriosis and IC/BPS. The overlapped symptoms may be related to cross-sensitization with transient receptor potential vanilloid 1 (TRPV1) and/or transient receptor potential ankyrin 1 (TRPA1) hyperexpression. This study was aimed at exploring whether bladder hypersensitivity is evoked in the surgically induced ectopic endometriosis rat and whether TRPV1 and/or TRPA1 play a vital role. METHODS: A total of 63 Sprague-Dawley female rats were divided into two groups, 39 for physiological examination and 24 for molecular analysis. Surgical induction of ectopic endometriosis (ENDO, n=27), surgical sham treatment (n=18), and treatment for endometriosis by GnRH analog (ENDO-G) (n=18) were performed. Bladder function was investigated by cystometry (for TRPV1 in the sham [n=6] and ENDO [n=9] groups and for TRPA1 in the sham [n=6], ENDO [n=9], and ENDO+G [n=9] groups), and TRPV1 and TRPA1 mRNA expressions were measured using real-time qPCR in the bladder and dorsal root ganglia (DRGs). RESULTS: On cystometry, the relative intercontraction interval (ICI) after/before resiniferatoxin (RTx; TRPV1 activator) infusion to the bladder showed no significant difference between the two groups, whereas relative ICI after/before allyl isothiocyanate (AITC; TRPA1 activator) infusion was significantly lower in the ENDO group than in the sham group. TRPA1 mRNA expression in the bladder and L5 DRG was considerably higher in the ENDO group than in the sham group on real-time qPCR. TRPA1 mRNA hyperexpression and bladder hypersensitivity after AITC infusion were reduced in the ENDO-G group. CONCLUSIONS: Bladder cross-sensitization in ENDO rats occurs in association with hyperexpression of TRPA1 at both the DRG and the bladder mucosa. This can be understood by the "cross-sensitization of endometriosis to bladder" theory explaining overlapping symptoms among BPS/IC and ectopic endometriosis.

Research on Omnidirectional Stereo Measurement Using Convex Mirrors and Vertical Disparity.

We propose an omnidirectional measurement method without blind spots by using a convex mirror, which in principle does not cause chromatic aberration, and by using vertical disparity by installing cameras at the top and bottom of the image. In recent years, there has been significant research in the fields of autonomous cars and robots. In these fields, three-dimensional measurements of the surrounding environment have become indispensable. Depth sensing with cameras is one of the most important sensors for recognizing the surrounding environment. Previous studies have attempted to measure a wide range of areas using fisheye and full spherical panoramic cameras. However, these approaches have limitations such as blind spots and the need for multiple cameras to measure all directions. Therefore, this paper describes a stereo camera system that uses a device capable of taking an omnidirectional image with a single shot, enabling omnidirectional measurement with only two cameras. This achievement was challenging to attain with conventional stereo cameras. The results of experiments confirmed an improvement in accuracy of up to 37.4% compared to previous studies. In addition, the system succeeded in generating depth image that can recognize distances in all directions in a single frame, demonstrating the possibility of omnidirectional measurement with two cameras.

Morphological and gonadal histological characteristics of the silver-phase male Indo-Pacific eel Anguilla marmorata.

Eight silver-phase male Indo-Pacific eels (giant mottled eels) Anguilla marmorata were collected from three small rivers on subtropical Amami-Oshima Island, Japan, and their morphological and gonadal-histological characteristics were examined. The total length, body mass and age of the silver eels were 543.8 ± 49.3 (496-659) mm, 376.0 ± 116.0 (282-660) g and 14.6 ± 2.3 (11-19) years old, respectively. The silvering-related characteristics (eye index, pectoral-fin index, gut-somatic index) and reproductive characteristics (gonadosomatic index, histological stage) of the silver eels were significantly advanced compared to those of yellow eels, which is similar to other anguillid species.

Increasing Heme Oxygenase-1-Expressing Macrophages Indicates a Tendency of Poor Prognosis in Advanced Colorectal Cancer.

BACKGROUND: Many cancers express heme oxygenase-1 -(HO-1) at a higher frequency than healthy tissues, and this elevated expression is associated with cancer prognosis. Here, we aim to clarify the correlation between HO-1-expressing macrophage numbers and clinicopathological parameters of advanced colorectal cancer. MATERIALS AND METHODS: Formalin-fixed and paraffin-embedded tissues of patients with advanced colorectal cancer were used. To detect HO-1 expression in macrophages, immunohistochemistry was performed. The number of positive cells was measured. Furthermore, HO-1 mRNA in colorectal cancer was examined by reverse transcription polymerase chain reaction. RESULTS: Among the HO-1-negative and HO-1-positive groups, 58.02 and 85.00% of cases, respectively, were positive for lymph node metastasis. The disease-free survival (DFS) time was significantly shorter (p < 0.05) in the -HO-1-positive group (2.44 years) than in the HO-1-negative group (4.09 years). However, according to the Cox proportional-hazards regression model, the HO-1-positive group could not be a risk factor of poor prognosis. HO-1 mRNA expression was confirmed in colorectal normal and cancer tissues. CONCLUSION: In this study, the correlation between HO-1-expressing macrophages and clinicopathological parameters in the tumor microenvironment of colorectal cancer was studied for the first time, and the expression was associated with lymph node metastasis and shortening of DFS.

Distribution of anguillid leptocephali and possible spawning areas in the South Pacific Ocean.

Seven South Pacific anguillid eel species live from New Guinea to French Polynesia, but their spawning areas and life histories are mostly unknown despite previous sampling surveys. A July-October 2016 research cruise was conducted to study the spawning areas and times, and larval distributions of South Pacific anguillid eels, which included a short 155°E station-line northeast of New Guinea and five long transects (5-25°S, 160°E-140°W) crossing the South Equatorial (SEC) and other currents. This survey collected nearly 4000 anguilliform leptocephali at 179 stations using an Isaacs-Kidd Midwater Trawl accompanied by 104 CTD casts. Based on mor-phometric observations and DNA sequencing, 74 anguillid leptocephali were collected, which in the southern areas included 29 larvae of six species: Anguilla bicolor pacifica, A. marmorata, A. australis, A. reinhardtii, A. megastoma, and A. obscura (all anguillid species of the region were caught except A. dieffenbachii). Small A. australis (9.0-16.8 mm) and A. reinhardtii (12.4, 12.5 mm) leptocephali were collected south of the Solomon Islands, other A. australis (10.8-12.0 mm) larvae were caught northwest of Fiji along with an A. obscura (20.0 mm) larva, and an A. marmorata (7.8 mm) larva was collected near Samoa. Considering collection sites, larval ages from otolith analysis, and westward SEC drift, multiple spawning locations occurred from south of the Solomon Islands and the Fiji area (16-20 days old larvae) to near Samoa (19 days old larva) during June and July in areas where high-salinity Subtropical Underwater (STUW, ~150 m depth) and the warm, low-salinity surface Fresh Pool were present. Five long hydrographic sections showed the strong Fresh Pool in the west and the STUW formation area in the east.

Night-Time Urinary Frequency Is Increased after the Great East Japan Earthquake along with Seasonal Variation: A Five-Year Longitudinal Study in Kesennuma City.

Disasters influence various health conditions; however, little has been reported about urinary symptoms. The objective of this study is to evaluate whether night-time urinary frequency was influenced by the Great East Japan Earthquake (GEJE) in March 2011. We also evaluated seasonal variation of night-time frequency, which may affect the primary objective. A retrospective chart review was conducted on 300 evaluable patients who resided in the impacted area: 263 men with benign prostatic hyperplasia and/or overactive bladder and 37 women with overactive bladder. Data concerning night-time frequency were collected repeatedly every three months from March 2009 until March 2014, then compared yearly and seasonally among same patients. In addition, night-time frequency was analyzed for potential relations to sex, age, comorbidities, and whether residences had been destroyed. There was a significant increase of night-time frequency during 2011-2013 when compared yearly with 2009 and 2010. In seasonal comparisons of the entire period, night-time frequency was greater during autumn and winter compared with summer. In quarterly comparisons, a sudden increase was not observed after the GEJE, but night-time frequency was increased significantly in spring, summer and autumn in 2011 when compared with the corresponding seasons in 2010. While hypertension was related to exacerbation of night-time frequency during winter, we did not find any factors associated with increase after the disaster out of sex, age, comorbidities or residential situations. In conclusion, night-time urinary frequency is increased shortly after the GEJE and remains elevated for the following three years along with seasonal variation.

Distribution of wild and stocked Japanese eels in the lower reaches of the Tone River catchment revealed by otolith stable-isotope ratios.

The natural occurrence of Japanese eels Anguilla japonica in Japan's highly altered catchments is a critical measure of habitat restoration and ecosystem health, yet this metric may be obscured by the incidence of co-occurring cultured eels. Distribution of wild and stocked A. japonica in the lower reaches of the Tone River cachment was investigated using otolith oxygen and carbon stable-isotope ratios (δ18 O and δ13 C). We developed a discrimination model to classify wild and cultured eels for 560 individuals and applied it to eels captured in the lower reaches of the Tone River catchment. Wild eels were found at all study sites of this part of the catchment, indicating natural recruitment of the species occurred from the estuary to third-order streams at least as far as Lake Imbanuma. The proportion of wild eels ranged from 86 to 100% at river and stream sites and was only 23% at upstream Lake Imbanuma sites. This difference probably depends on whether or not eels were released near the corresponding site. More than 50% of stocked eels occurred at sites proximate to release locations, indicating limited dispersal by cultured eels.

[Availability of Local Therapy to Castration-Resistant Prostate Cancer for M0 Patients with Initial Prostate Specific Antigen 100 ng/ml or Higher].

Prostate cancer patients with initial PSA 100 ng/ml or greater who received transrectal ultrasoundguided prostate biopsy and were staged as M0 by imaging studies from 2011 to 2014 in seven hospitals, were enrolled in the study. Castration-resistant prostate cancer (CRPC)-free survival was compared between the two treatment groups : androgen deprivation therapy (ADT) alone and ADT plus local therapy. Of 142 prostate cancer patients with initial PSA 100 ng/ml or greater, 49 (34.5%) had no metastases and final analysis was performed on 46 patients. Thirty one M0 patients received ADT alone, and 15 received ADT plus local therapy. During follow-up (median 31 months, range 1-56 months) 13 patients (42%) in the ADT alone group progressed to CRPC. One- and two-year CRPC-free survival rates were 72.5 and 53%, respectively. No patients with ADT plus local therapy developed CRPC, and time to CRPC was prolonged significantly (p=0.002). On multivariate analysis for the group with ADT alone, PSA nadir of more than 0. 2 ng/ml and cN1 were independent predictors for progression to CRPC (p=0.009, 0.031). About one third of prostate cancer patients with initial PSA 100 ng/ml or greater had clinically no metastases. Local therapy to prostate combined with ADT may prolong time to CRPC compared with ADT alone. A subset of men with a PSA nadir of more than 0.2 ng/ml after ADT and cN1 could benefit from local therapy.

The Drosophila lingerer protein cooperates with Orb2 in long-term memory formation.

Recently mated Drosophila females were shown to be reluctant to copulate and to exhibit rejecting behavior when courted by a male. Males that experience mate refusal by a mated female subsequently attenuate their courtship effort toward not only mated females but also virgin females. This courtship suppression persists for more than a day, and thus represents long-term memory. The courtship long-term memory has been shown to be impaired in heterozygotes as well as homozygotes of mutants in orb2, a locus encoding a set of CPEB RNA-binding proteins. We show that the impaired courtship long-term memory in orb2-mutant heterozygotes is restored by reducing the activity of lig, another putative RNA-binding protein gene, yet on its own the loss-of-function lig mutation is without effect. We further show that Lig forms a complex with Orb2. We infer that a reduction in the Lig levels compensates the Orb2 deficiency by mitigating the negative feedback for Orb2 expression and thereby alleviating defects in long-term memory.

Docetaxel, cisplatin and 5-fluorouracil chemotherapy with concurrent radiation for unresectable advanced urethral carcinoma.

The present case report describes two cases of unresectable advanced primary urethral carcinoma. Case 1 was a 61-year-old man with squamous cell carcinoma of the urethra that directly invaded into the perineal skin. Case 2 was a 64-year-old woman with adenocarcinoma, and solitary lung and lymph node metastases. Both patients received docetaxel/cisplatin/5-fluorouracil chemotherapy with concurrent radiation. The docetaxel/cisplatin/5-fluorouracil chemotherapy regimen consisted of docetaxel (75 mg/m(2) ) on day 2, cisplatin (100 mg/m(2) ) on day 2 and 5-fluorouracil (1000 mg/m(2) ) on days 1 to 5 and was repeated every 4 weeks. Complete response was achieved after two cycles of chemotherapy combined with radiation in case 1. In case 2, complete response was achieved locally after six cycles of chemotherapy combined with radiation, but the solitary lung lesion remained viable. We experienced two cases with advanced urethral carcinoma for whom docetaxel/cisplatin/5-fluorouracil chemotherapy chemotherapy with radiation was effective.

A case of testicular tumor and respiratory failure caused by choriocarcinoma syndrome managed through modified chemotherapy and extracorporeal membrane oxygenation.

Introduction: Choriocarcinoma syndrome with multiple lung metastases has a poor prognosis and causes respiratory failure due to alveolar hemorrhage. We encountered a case where the introduction of extracorporeal membrane oxygenation effectively sustained oxygenation until chemotherapy took effect on lung metastases of testicular tumors. Case presentation: A 35-year-old man with dyspnea was referred to our hospital. He showed left testicular tumor with multiple lung metastases. Serum human chorionic gonadotropin level was also elevated. Reduced chemotherapy was initiated and extracorporeal membrane oxygenation was administered because of low oxygen levels on the fourth day. Chemotherapy successfully reduced the size of the lung masses, and extracorporeal membrane oxygenation was discontinued. Respiratory status improved substantially, but the patient died of brain metastases 4 months later. Conclusion: Extracorporeal membrane oxygenation may be a useful option for managing respiratory failure resulting from choriocarcinoma syndrome until the respiratory condition is improved by chemotherapy for testicular tumors.

Expression of acetylated and dimethylated histone H3 in colorectal cancer.

AIM: The expression of acetylated and dimethylated histone H3 in colorectal cancer was examined by immunohistochemistry and chromatin immunoprecipitation (ChIP)/Western blot (WB) assay. The correlation between the expression of histone H3 and clinicopathological findings was analyzed. METHODS: Formalin-fixed and paraffin-embedded sections obtained from 80 operated cases of colorectal cancer were immunostained with anti-acetylated histone H3 (H3Ac) antibody and anti-dimethylated histone H3 lysine 4 (H3K4) antibody. Positive immunoreactivity was evaluated using the Allred scoring system. Furthermore, the expression was confirmed by ChIP/WB assay using formalin-fixed and paraffin-embedded sections. RESULTS: There was good correlation between immunostaining and expression on ChIP/WB assay (p = 0.0005). There was a significant difference between the Allred score of H3K4 and the depth of tumor invasion (p = 0.0003) and the pathological stages (p = 0.0065). In overall survival classified by Allred scores of H3Ac (p = 0.0072) and H3K4 (p = 0.0187), the highest scores represented significantly worse prognoses than the other scores. Specifically, in stages II and III, the highest scores represented significantly worse prognoses than the other scores (p < 0.0001 and p = 0.0173, respectively). CONCLUSION: The expression of H3Ac and H3K4 may estimate patient prognosis.

[A case of relapsed colon cancer successfully treated by capecitabine].

We report a case of advanced relapsed colon cancer, which had multiple liver and spleen metastasis, controlled for about two years by capecitabine therapy. A 60-year-old female had been diagnosed with ileus due to sigmoid colon cancer in August, 2005. She received sigmoidectomy and adjuvant chemotherapy (Leucovorin/5-fluorouracil therapy). In postoperative observation, multiple liver and spleen metastasis were detected by computed tomography in February, 2008. Therefore, she was administered twenty courses of FOLFOX therapy. However, a peripheral nerve disturbance appeared. There fore chemotherapy was changed from FOLFOX therapy to FOLFIRI therapy. After 2 courses of FOLFIRI therapy, she had severe nausea, vomiting, appetite loss and diarrhea. Therefore, chemotherapy was changed from FOLFIRI therapy to capecitabine therapy. After capecitabine therapy, her multiple liver and spleen metastasis disappeared, and complete response has continued for about 2 years. She has remained on capecitabine therapy and has a good quality of life.

INPP5D modulates TREM2 loss-of-function phenotypes in a ß-amyloidosis mouse model.

The genetic associations of TREM2 loss-of-function variants with Alzheimer disease (AD) indicate the protective roles of microglia in AD pathogenesis. Functional deficiencies of TREM2 disrupt microglial clustering around amyloid ß (Aß) plaques, impair their transcriptional response to Aß, and worsen neuritic dystrophy. However, the molecular mechanism underlying these phenotypes remains unclear. In this study, we investigated the pathological role of another AD risk gene, INPP5D, encoding a phosphoinositide PI(3,4,5)P3 phosphatase expressed in microglia. In a Tyrobp-deficient TREM2 loss-of-function mouse model, Inpp5d haplodeficiency restored the association of microglia with Aß plaques, partially restored plaque compaction, and astrogliosis, and reduced phosphorylated tau+ dystrophic neurites. Mechanistic analyses suggest that TREM2/TYROBP and INPP5D exert opposing effects on PI(3,4,5)P3 signaling pathways as well as on phosphoproteins involved in the actin assembly. Our results suggest that INPP5D acts downstream of TREM2/TYROBP to regulate the microglial barrier against Aß toxicity, thereby modulates Aß-dependent pathological conversion of tau.

Effect of Different Approaches to Antimicrobial Therapy with Cefmetazole and Meropenem on the Time to Defervescence in Non-Severe Extended-Spectrum ß-Lactamase-Producing Escherichia coli Bacteremia.

Carbapenems are antimicrobial agents commonly used to treat extended-spectrum ß-lactamase (ESBL)-producing bacteria. Although cefmetazole (CMZ) is considered effective for ESBL-producing Escherichia coli (ESBL-EC) bacteremia, previous studies showed its limitations, including the influence of the initial antimicrobial agent. Here, we examined the effects of different approaches to antimicrobial therapy with CMZ and meropenem (MEPM) on the time to defervescence in ESBL-EC bacteremia. Notably, the influence of previous antimicrobial agents was excluded. Inpatients with ESBL-EC detected in blood cultures between April 2018 and March 2023 were included and assigned to CMZ (n = 14), MEPM (n = 8), de-escalation to CMZ (dCMZ; n = 9), or escalation to MEPM (eMEPM; n = 11) groups. The median time to defervescence was 3.5, 1.0, 2.0, and 4.0 days in the CMZ, MEPM, dCMZ, and eMEPM groups, respectively, with no significant differences. Cox proportional hazards analysis showed a significant difference in the hazard ratio (95% confidence interval) of 0.378 (0.145-0.984) for the time to defervescence with CMZ versus MEPM (p = 0.046). The extent of a delayed time to defervescence is greater with early CMZ administration than with MEPM administration in patients with non-severe ESBL-EC bacteremia.

Responses to antibiotics in human iPSC-derived neurons based on the clinical antibiotic-associated encephalopathy classification.

Antibiotic-associated encephalopathy (AAE) is a central nervous system disorder caused by antibiotics administration and classified into three types based on clinical symptoms. Type 1 AAE causes seizures and myoclonus, type 2 causes psychiatric symptoms, and type 3 is characterized by cerebellar ataxia. In this study, we investigated whether the electrical activity of in vitro human iPSC-derived neurons to antibiotics could be classified based on the 3 types of AAEs classified by clinical symptoms. Glutamatergic, GABAergic neurons and astrocytes differentiated from human iPS cells were seeded on micro-electrode array (MEA). The cumulative administration of 13 different antimicrobials detected changes in neural activity that differed according to AAE type. Next, we classified the antimicrobials by principal component analysis (PCA) and confirmed the AAE type of each agent. We found that Types 1-3 AAE agents were distributed separately. The classification of antibiotics depending on electrophysiological response characteristics was consistent with the clinical practice classification of AAEs. In conclusion, the combination of electrophysiological responses of human iPS cell-derived neural networks measured by MEA plus multivariate analysis methods will effectively detect and classify antibiotics developmental risks.

Natal origin of Pacific bluefin tuna Thunnus orientalis determined by SIMS oxygen isotope analysis of otoliths.

Accurate understanding of changing population dynamics associated with climate change is critical for managing highly migratory fish species. However, long-term data on population dynamics and the resulting recruitment variability is still lacking for many species, making it difficult to predict and integrate the effects of ocean warming into management schemes. In this study, high-resolution stable oxygen isotope (δ18O) analysis was performed on the otoliths of adult Pacific bluefin tuna Thunnus orientalis using secondary ion mass spectrometry (SIMS) to determine the natal origin of an individual fish. The core δ18Ootolith corresponding to the larval stage greatly varied among the individuals, indicating that the larvae experienced a wide range of thermal environments. The non-hierarchical cluster analysis performed on the core δ18Ootolith grouped fish into those with higher δ18Ootolith (lower temperature) and those with lower δ18Ootolith (higher temperature), most likely representing relative temperature difference experienced between fish born in the Sea of Japan and in the Nansei Islands area. The Nansei Islands area cluster showed more variability in the early otolith growth indicating a longer spawning season, which is consistent with the observed longer spawning duration in this area. The absolute temperature estimates based on the SIMS-measured core δ18Ootolith were significantly higher than those expected from sea surface temperature data, suggesting the effects of matrix-related bias on the temperature offsets. The relative temperature difference, however, matched well with the known spawning temperature range of the two spawning grounds. The recruitment contribution from each spawning ground (all year-classes pooled, n = 51) was 45% in the Sea of Japan and 55% in the Nansei Islands area. Overall, this study demonstrated the effectiveness of SIMS δ18Ootolith analysis for investigating the natal origin of fish and its potential application in fish population dynamics studies.