Mutual oligosynaptic inhibition of group Ia afferents between the anterior and posterior parts of the deltoid in humans.

The anterior (DA) and posterior parts of the deltoid (DP) show alternating contraction during shoulder flexion and extension movements. It is expected that an inhibitory spinal reflex between the DA and DP exists. In this study, spinal reflexes between the DA and DP were examined in healthy human subjects using post-stimulus time histogram (PSTH) and electromyogram averaging (EMG-A). Electrical conditioning stimulation was delivered to the axillary nerve branch that innervates the DA (DA nerve) and DP (DP nerve) with the intensity below the motor threshold. In the PSTH study, the stimulation to the DA and DP nerves inhibited (decrease in the firing probability) 31 of 54 DA motor units and 31 of 51 DP motor units. The inhibition was not provoked by cutaneous stimulation. The central synaptic delay of the inhibition between the DA and DP nerves was 1.5 ± 0.5 ms and 1.4 ± 0.4 ms (mean ± SD) longer than those of the homonymous facilitation of the DA and DP, respectively. In the EMG-A study, conditioning stimulation to the DA and DP nerves inhibited the rectified and averaged EMG of the DP and DA, respectively. The inhibition diminished with tonic vibration stimulation to the DA and DP and recovered 20-30 min after vibration removal. These findings suggest that oligo(di or tri)-synaptic inhibition mediated by group Ia afferents between the DA and DP exists in humans.

Two-session embolization of portosystemic shunt presenting with hepatic encephalopathy via transvenous and trans-paraumbilical approaches: A case report.

We describe the endovascular embolization of a 65-year-old man with chronic hepatic encephalopathy. A contrast-enhanced computed tomography demonstrated a splenorenal shunt and a recanalized paraumbilical vein as a continuous portal shunt connecting the left branch of the portal vein and the right common femoral vein. A 2-session embolization was performed for the splenorenal shunt. First, the transvenous approach was used for coil embolization of the splenorenal shunt. It was difficult to advance the catheter system to the embolization site, and it was unstable during coil placement. Second, the paraumbilical venous approach was used to place additional coils. The catheter system had good maneuverability and easily reached the embolization site. Additionally, the stable system allowed for densely packed additional coil implantations. This report demonstrated the paraumbilical venous approach's effectiveness in catheter maneuverability and system stability during coil embolization.

Comparison of Echocardiography and Myocardial Scintigraphy to Detect Cancer Therapy-Related Cardiovascular Toxicity in Breast Cancer Patients.

The mortality rate of cancer patients has been decreasing; however, patients often suffer from cardiac disorders due to chemotherapy or other cancer therapies (e.g., cancer-therapy-related cardiovascular toxicity (CVR-CVT)). Therefore, the field of cardio-oncology has drawn more attention in recent years. The first European Society of Cardiology (ESC) guidelines on cardio-oncology was established last year. Echocardiography is the gold standard for the diagnosis of CVR-CVT, but many breast cancer patients are unable to undergo echocardiography due to their surgery wounds or anatomical reasons. We performed a study to evaluate the usefulness of myocardial scintigraphy using Iodine-123 ß-methyl-P-iodophenyl-pentadecanoic acid (123I-BMIPP) in comparison with echocardiography and published the results in the Journal of Imaging last year. This is the secondary analysis following our previous study. A total of 114 breast cancer patients who received chemotherapy within 3 years underwent echocardiography, as well as Thallium (201Tl) and 123I-BMIPP myocardial perfusion and metabolism scintigraphy. The ratio of isotope uptake reduction was scored by Heart Risk View-S software (Nihon Medi-Physics). The scores were then compared with the echocardiography parameters. All the patients' charts and data from January 2022 to November 2023 were reviewed for the secondary analysis. Echocardiogram parameters were obtained from 99 patients (87% of total patients). No correlations were found between the echocardiography parameters and Heart Risk View-S scores of 201Tl myocardial perfusion scintigraphy, nor those of the BMIPP myocardial metabolism scintigraphy. In total, 8 patients out of 114 (7.0%) died within 22 months, while 3 patients out of 26 CVR-CVT patients (11.5%) died within 22 months. Evaluation by echocardiography was sometimes difficult to perform on breast cancer patients. However, other imaging modalities, including myocardial scintigraphy, cannot serve as alternatives to echocardiography. Cardiac scintigraphy detects circulation disorder or metabolism disorder in the myocardium; therefore, it should be able to reveal myocardial damage to some extent. The mortality rate of breast cancer patients was higher with CVR-CVT. A new modality to detect CVR-CVT besides echocardiography can possibly be anticipated for patients who cannot undergo echocardiography.

SMAD2/3 signaling regulates initiation of mouse Wolffian ducts and proximal differentiation in Müllerian ducts.

Male and female reproductive tracts develop from anterior intermediate mesoderm with similar differentiation processes. The anterior intermediate mesoderm develops into the mesonephros, and the Wolffian duct initiates by epithelialization in the mesonephros. The Müllerian duct invaginates from the coelomic epithelium of the cranial mesonephros for ductal formation and is then regionalized into proximal to caudal female reproductive tracts. In this study, we focused on the epithelialization of the Wolffian duct, initiation of the Müllerian duct, and the regionalization step of the Müllerian ducts as a continuous process. By using intermediate mesodermal cells from mouse pluripotent stem cells, we identified that inhibition of SMAD2/3 signaling might be involved in the differentiation into mesenchymal cells, after which mesonephric cells might be then epithelialized during differentiation of the Wolffian duct. Aggregation of coelomic epithelial cells might be related to initiation of the Müllerian duct. Transcriptomic analysis predicted that consensus sequences of SMAD3/4 were enriched among highly expressed genes in the proximal Müllerian duct. SMAD2/3 signaling to regulate differentiation of the Wolffian duct was continuously activated in the proximal Müllerian duct and was involved in proximal and oviductal regionalization. Therefore, SMAD2/3 signaling may be finely tuned to regulate differentiation from initiation to regionalization steps.

A case of percutaneous transhepatic portal vein stenting without using iodinated contrast media for post pancreatectomy portal vein obstruction.

Postoperative portal vein obstruction could occur as a complication of portal vein reconstruction during hepatic lobectomy or pancreaticoduodenectomy. We report a case of patient with postoperative portal vein obstruction treated with percutaneous transhepatic portal vein stenting without using iodinated contrast media owing to a history of severe allergic reactions. Under ultrasound guidance, carbon dioxide angiography, and appropriate device selection, successful stenting was achieved without serious adverse events. After the operation, portal vein blood flow and clinical symptoms improved, enabling adjuvant chemotherapy. To the best of our knowledge, this is the first case report wherein percutaneous transhepatic portal vein stenting was successfully performed in a patient with an iodine allergy.

Survey of diversity awareness and environment among members of the Pediatric Rheumatology Association of Japan.

BACKGROUND: Diversity management has gained traction in Japan. The Pediatric Rheumatology Association of Japan (PRAJ) has an Advisory Committee for Diversity Promotion with a broader focus on promoting diversity. The objectives of this study were to better understand the problems faced by PRAJ members regarding the work environment, childcare and nursing care, and work-life balance. METHODS: A web-based questionnaire was administered to members of the PRAJ and 79 responses were evaluated. RESULTS: Of the respondents, 73% were male and 27% were female. A total of 14% worked for more than 12 h on weekdays, and 22% worked for more than 60 h per week and 38% had fewer than 4 days off per month. Regarding childcare, 54% of the respondents were raising preschool children and 83% had taken parental leave for less than 1 year. A total of 17% of participants had family members in need of care. For both childcare and caregiving, the burden was greater for women. Only 18% of the respondents reported a well-balanced work-life balance, and the most common reasons for a lack of balance were not having enough time, heavy workload, and heavy housework load. CONCLUSIONS: The working hours of the respondents were long, and female members had a greater burden of childcare and caregiving, which was considered a barrier to the career development of women. In the future, there will be a need to promote a sense of equality in diverse human resources, develop support for family life, and shorten working hours.

Diagnostic Performance of Preoperative Imaging in Endometrial Cancer.

BACKGROUND: Endometrial cancer is one of the most common gynecological malignancies. Because the findings mentioned in radiogram interpretation reports issued by diagnostic radiologists influence treatment strategies, we aimed to evaluate the diagnostic accuracy of preoperative computed tomography (CT) and magnetic resonance imaging (MRI) interpretation results in clinically relevant settings. METHODS: The clinical records of patients diagnosed with endometrial cancer treated at Tohoku University Hospital from January 2012 to December 2021 were reviewed. The preoperative and pathologically estimated cancer stages were compared based on the results mentioned in the radiogram interpretation report. RESULTS: The preoperative and postoperative cancer stages were concordant in 70.0% of the patients. By contrast, the cancer stage was underdiagnosed and overdiagnosed in 21.7% and 8.2% of the patients, respectively. The sensitivities of MRI for deep myometrial invasion, cervical stromal invasion, vaginal invasion, and adnexal metastasis were 65.1%, 58.2%, 33.3%, and 18.4%, respectively. The sensitivity and specificity for pelvic lymph node metastasis using a combination of CT and MRI were 40.9% and 98.4%, respectively. Those for para-aortic lymph node metastases using CT were 37.0% and 99.5%, respectively. CONCLUSIONS: The low sensitivity observed in this study clarified the limitations of preoperative diagnostic performance in current clinical practice.

Comparative analysis of gonadal transcriptomes between turtle and alligator identifies common molecular cues activated during the temperature-sensitive period for sex determination.

The mode of sex determination in vertebrates can be categorized as genotypic or environmental. In the case of genotypic sex determination (GSD), the sexual fate of an organism is determined by the chromosome composition with some having dominant genes, named sex-determining genes, that drive the sex phenotypes. By contrast, many reptiles exhibit environmental sex determination (ESD), whereby environmental stimuli drive sex determination, and most notably temperature. To date, temperature-dependent sex determination (TSD) has been found in most turtles, some lizards, and all crocodylians, but commonalities in the controlling processes are not well established. Recent innovative sequencing technology has enabled investigations into gonadal transcriptomic profiles during temperature-sensitive periods (TSP) in various TSD species which can help elucidate the controlling mechanisms. In this study, we conducted a time-course analysis of the gonadal transcriptome during the male-producing temperature (26℃) of the Reeve's turtle (Chinese three-keeled pond turtle) Mauremys reevesii. We then compared the transcriptome profiles for this turtle species during the TSP with that for the American alligator Alligator mississippiensis to identify conserved reptilian TSD-related genes. Our transcriptome-based findings provide an opportunity to retrieve the candidate molecular cues that are activated during TSP and compare these target responses between TSD and GSD turtle species, and between TSD species.

Hepatic compartment syndrome treated with damage control surgery and transarterial embolization: A case report.

Background: Hepatic compartment syndrome (HCS) is a complication of nonoperative management in patients with blunt hepatic injury. Although decompression of elevated intrahepatic pressure through surgical exploration or drainage and hemorrhage control are required to manage this condition, evidence for such a management for this complication is insufficient. Herein, we report a pediatric patient treated with a planned combination strategy of surgical decompression with perihepatic packing to reduce intrahepatic pressure and subcapsular hemorrhage control as well as angioembolization to control intraparenchymal hemorrhage. Case presentation: A 12-year-old boy was referred to our emergency department 5 h after sustaining severe bruising in the upper abdomen in a traffic accident. Computed tomography (CT) showed an intraparenchymal hematoma in the right lobe of the liver; nonoperative management was selected based on stable hemodynamic status. Two days after the injury, he complained of severe abdominal pain and shock. CT showed an intraparenchymal and large subcapsular hematoma with right branch compression of the portal vein and extravasation of contrast material. Laboratory data showed progression of hepatocellular damage. We successfully managed this patient with a planned combination strategy of surgical decompression with perihepatic packing for reduction of intrahepatic pressure and subcapsular hemorrhage control, followed by angioembolization for control of intraparenchymal hemorrhage. Conclusion: Our study suggests that for the management of HCS, a planned combination strategy of damage control surgery and angioembolization is a therapeutic option.

Development of microfluidic devices for on-site water quality testing using glass molding process.

The demand for multi-point water quality monitoring is increasing to solve the global problem of safe drinking water supply and environmental water contamination by industries. Therefore, compact devices are needed for on-site water quality analysis. On-site devices require low cost and high durability because they are placed outdoors, exposing them to strong ultraviolet rays and a wide range of temperatures. Our previous study reported on a compact and low-cost water quality meter that uses microfluidic devices with resin to monitor chemicals. In this study, we extended the fabrication range of the glass molding method to fabricate a glass microfluidic device with a 300 µm deep channel on a 50 mm in diameter substrate for constructing a low-cost and high-durability device. Finally, we developed a low-cost, highly robust glass device with a diamond-like carbon-coated channel surface to measure residual chlorine. The experimental results indicated that this device can endure outdoor conditions and be attached to small internet of things devices for analyzing chemical substances, such as residual chlorine.

Evolutionary differentiation of androgen receptor is responsible for sexual characteristic development in a teleost fish.

Teleost fishes exhibit complex sexual characteristics in response to androgens, such as fin enlargement and courtship display. However, the molecular mechanisms underlying their evolutionary acquisition remain largely unknown. To address this question, we analyse medaka (Oryzias latipes) mutants deficient in teleost-specific androgen receptor ohnologs (ara and arb). We discovered that neither ar ohnolog was required for spermatogenesis, whilst they appear to be functionally redundant for the courtship display in males. However, both were required for reproductive success: ara for tooth enlargement and the reproductive behaviour eliciting female receptivity, arb for male-specific fin morphogenesis and sexual motivation. We further showed that differences between the two ar ohnologs in their transcription, cellular localisation of their encoded proteins, and their downstream genetic programmes could be responsible for the phenotypic diversity between the ara and arb mutants. These findings suggest that the ar ohnologs have diverged in two ways: first, through the loss of their roles in spermatogenesis and second, through gene duplication followed by functional differentiation that has likely resolved the pleiotropic roles derived from their ancestral gene. Thus, our results provide insights into how genome duplication impacts the massive diversification of sexual characteristics in the teleost lineage.

Iodine-123 ß-methyl-P-iodophenyl-pentadecanoic Acid (123I-BMIPP) Myocardial Scintigraphy for Breast Cancer Patients and Possible Early Signs of Cancer-Therapeutics-Related Cardiac Dysfunction (CTRCD).

(1) Background: The mortality of breast cancer has decreased due to the advancement of cancer therapies. However, more patients are suffering from cancer-therapeutics-related cardiac dysfunction (CTRCD). Diagnostic and treatment guidelines for CTRCD have not been fully established yet. Ultrasound cardiogram (UCG) is the gold standard for diagnosis of CTRCD, but many breast cancer patients cannot undergo UCG due to the surgery wounds or anatomical reasons. The purpose of the study is to evaluate the usefulness of myocardial scintigraphy using Iodine-123 ß-methyl-P-iodophenyl-pentadecanoic acid (123I-BMIPP) in comparison with UCG. (2) Methods: 100 breast cancer patients who received chemotherapy within 3 years underwent Thallium (201Tl) and 23I-BMIPP myocardial perfusion and metabolism scintigraphy. The images were visually evaluated by doctors and radiological technologists, and the grade of uptake reduction was scored by Heart Risk View-S software (Nihon Medi-Physics). The scores were deployed in a 17-segment model of the heart. The distribution of the scores were analyzed. (3) Results: Nine patients (9%) could not undergo UCG. No correlation was found between left ventricular ejection fraction (LVEF) and Heart Risk View-S scores of 201Tl myocardial perfusion scintigraphy nor those of BMIPP myocardial metabolism scintigraphy. In a 17-segment model of the heart, the scores of the middle rings were higher than for the basal ring. (4) Conclusions: Evaluation by UCG is not possible for some patients. Myocardial scintigraphy cannot serve as a perfect alternative to UCG. However, it will become the preferable second-choice screening test, as it could point out the early stage of CTRCD.

Monosynaptic facilitation of flexor digitorum superficialis motoneurons mediated by Group Ia afferents from the extensor carpi radialis in humans.

Wrist position is known to affect the grip strength. We focused on the spinal reflex arc, which would support the movement, and investigated the effects of low-threshold afferents from the extensor carpi radialis (ECR) on the excitability of the flexor digitorum superficialis (FDS) motoneurons using the post-stimulus time-histogram (PSTH) and electromyogram-averaging (EMG-A) methods. Electrical conditioning stimulation of an intensity below the motor threshold was applied to the radial nerve branch innervating the ECR. In the PSTH study, changes in the firing probability of single motor units after electrical conditioning stimulation were investigated in seven subjects. An early and significant peak (increase in the firing probability: facilitation) was recorded for 36/60 FDS motor units. The remaining 24 motor units did not show any effects. Weak mechanical conditioning stimulation of the ECR muscle belly induced a similar peak. The central latency of the facilitation was equivalent to that of the homonymous monosynaptic facilitation. In the EMG-A study, changes in the rectified and averaged electromyograms of FDS induced by conditioning stimulation were examined in 12 subjects. An early and significant peak (facilitation) was induced by both electrical and mechanical conditioning stimulations. The facilitation decreased after withdrawal of the vibration to the ECR muscle belly. The facilitation was never induced by cutaneous nerve stimulation in the PSTH and EMG-A studies. These findings suggest that Group Ia afferents from the ECR increase the excitability of FDS motoneurons through a monosynaptic path in the spinal cord. These reflex arcs likely facilitate hand grasping movements.

Gel-electrophoresis based method for biomolecular interaction.

Electrophoresis is one of the most important analytical technologies for characterization of macromolecules and their interactions. Among them, native gel electrophoresis is used to analyze the macromolecules in the native structure. It differs in principle and information from those obtained by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) or blue native polyacrylamide gel electrophoresis (BN-PAGE). SDS-PAGE is carried out in the presence of strong denaturant, SDS, while BN-PAGE is done in the presence of negatively charged dye, e.g., Coomassie brilliant blue, G-250. Here, we describe native gel electrophoresis using agarose gel and a buffer at pH 6.1 composed of histidine and 2-(N-morpholino) ethanesulfonic acid. First, a protocol for vertical and horizontal formats of agarose native gel electrophoresis is described followed by different staining procedures. Then, various examples obtained using the developed procedure will be shown to demonstrate how the technology can be applied to specific cases and the advantages or caveats of the present technology.

Diagnosis and Pathogenesis of Sarcopenia in Chronic Liver Disease Using Liver Magnetic Resonance Imaging.

Background Liver magnetic resonance imaging (MRI) is rarely used to evaluate sarcopenia. This study sought to develop new diagnostic criteria for MRI in Asians and investigate the relationship between adipopenia and sarcopenia using MRI proton density fat fraction (PDFF), which is correlated with body fat mass. Methodology This study included 512 patients with chronic liver disease (CLD) who underwent magnetic resonance elastography (MRE). The following parameters were assessed: paraspinal muscle area/height index (PSMI) measured at the level of the superior mesenteric artery and PDFF. The cutoff PSMI and PDFF values for the diagnosis of sarcopenia and adipopenia, respectively, were determined using receiver operating characteristic analysis of Asians with low body mass index. Results Among patients with CLD, the prevalence rates of sarcopenia and adipopenia were 25% and 17%, respectively. We found that sarcopenia increased from stage 3 fibrosis and was inversely correlated with steatosis grade. Multivariate analysis found that MRI-PDFF was associated with sarcopenia. The Kaplan-Meier method in cirrhosis (n = 122) showed that the non-sarcopenia, sarcopenia, and sarcopenia/adipopenia groups had three-year survival rates of 97%, 55% (p < 0.01), and 23%, respectively. The Cox proportional hazards model identified the Child-Pugh score and sarcopenia/adipopenia as independent prognostic factors. Conclusions The new diagnostic criteria for sarcopenia confirmed that the prognosis of cirrhosis can be stratified. Furthermore, sarcopenia with adipopenia was shown to be a phenotype of severe sarcopenia in cirrhosis, and screening for sarcopenia should include cases in the precirrhotic stage.

Effect of thyroid hormone-disrupting chemicals on swim bladder inflation and thyroid hormone-related gene expression in Japanese medaka and zebrafish.

We compared the influence of thyroid hormone-disrupting chemicals (heptafluorobutanoic acid, PFBA and tris[1,3-dichloro-2-propyl] phosphate, TDCPP) and thyroid hormone (3,3',5-triiodo-L-thyronine, T3) on swim bladder inflation and thyroid hormone-related gene expression in Japanese medaka and zebrafish. The swim bladder of most larvae had inflated at 4 h post hatching (hph) in Japanese medaka and at 48 hph in zebrafish in controls. In both fish species, the swim bladder inflation was inhibited in larvae exposed to PFBA (lowest observed effect concentration [LOEC] in medaka: 40 mg/L; in zebrafish: 80 mg/L), TDCPP (LOEC in medaka: 1 mg/L; in zebrafish: 0.5 mg/L), and T3 (no inhibition in Japanese medaka; LOEC in zebrafish: 7.5 µg/L). We also examined the influence of PFBA, TDCPP, and T3 on the expression of thyroid stimulating hormone subunit beta (tshß) or thyroid hormone receptor alpha (trα) and beta (trß). No changes were observed in the expression of genes after PFBA and TDCPP exposure; however, T3 exposure upregulated trα and trß expression in both fish species. When the results were compared between Japanese medaka and zebrafish, swim bladder inflation in both species was found to be inhibited by exposure to thyroid hormone-disrupting chemicals. Our results show that inhibition of the swim bladder inflation at 4 hph in Japanese medaka and 48 hph in zebrafish is a potential indicator of thyroid hormone-disturbing activity of chemicals.

Longitudinal increase in albumin-bilirubin score is associated with non-malignancy-related mortality and quality of life in patients with liver cirrhosis.

Due to the developments in the treatment for hepatitis, it is possible to prevent the progression of liver fibrosis and improve patients' prognosis even if it has already led to liver cirrhosis (LC). Consequently, a two-step study was conducted. To begin with, a retrospective study was conducted to identify the potential predictors of non-malignancy-related mortality from LC. Then, we prospectively analyzed the validity of these parameters as well as their association with patients' quality of life. In the retrospective study, 89 cases were included, and the multivariate Cox regression analysis indicated that age (P = 0.012), model for end-stage liver disease (MELD) score (P = 0.012), and annual rate of change of the albumin-bilirubin (ALBI) score (P < 0.001) were significantly associated with LC prognosis. In the prospective study, 70 patients were included, and the patients were divided into cirrhosis progression and non-progression groups. The univariate logistic regression analysis indicated the serum procollagen type III N-terminal peptide level (P = 0.040) and MELD score (P = 0.010) were significantly associated with the annual rate of change of the ALBI score. Furthermore, the mean Chronic Liver Disease Questionnaire score worsened from 5.3 to 4.9 in the cirrhosis progression group (P = 0.034). In conclusion, a longitudinal increase in the ALBI score is closely associated with non-malignancy-related mortality and quality of life.

Crystal structure of CmABCB1 multi-drug exporter in lipidic mesophase revealed by LCP-SFX.

CmABCB1 is a Cyanidioschyzon merolae homolog of human ABCB1, a well known ATP-binding cassette (ABC) transporter responsible for multi-drug resistance in various cancers. Three-dimensional structures of ABCB1 homologs have revealed the snapshots of inward- and outward-facing states of the transporters in action. However, sufficient information to establish the sequential movements of the open-close cycles of the alternating-access model is still lacking. Serial femtosecond crystallography (SFX) using X-ray free-electron lasers has proven its worth in determining novel structures and recording sequential conformational changes of proteins at room temperature, especially for medically important membrane proteins, but it has never been applied to ABC transporters. In this study, 7.7 mono-acyl-glycerol with cholesterol as the host lipid was used and obtained well diffracting microcrystals of the 130 kDa CmABCB1 dimer. Successful SFX experiments were performed by adjusting the viscosity of the crystal suspension of the sponge phase with hy-droxy-propyl methyl-cellulose and using the high-viscosity sample injector for data collection at the SACLA beamline. An outward-facing structure of CmABCB1 at a maximum resolution of 2.22 Šis reported, determined by SFX experiments with crystals formed in the lipidic cubic phase (LCP-SFX), which has never been applied to ABC transporters. In the type I crystal, CmABCB1 dimers interact with adjacent molecules via not only the nucleotide-binding domains but also the transmembrane domains (TMDs); such an interaction was not observed in the previous type II crystal. Although most parts of the structure are similar to those in the previous type II structure, the substrate-exit region of the TMD adopts a different configuration in the type I structure. This difference between the two types of structures reflects the flexibility of the substrate-exit region of CmABCB1, which might be essential for the smooth release of various substrates from the transporter.

Summary of 17 chemicals evaluated by OECD TG229 using Japanese Medaka, Oryzias latipes in EXTEND 2016.

In June 2016, the Ministry of the Environment of Japan announced a program "EXTEND2016" on the implementation of testing and assessment for endocrine active chemicals, consisting of a two-tiered strategy. The aim of the Tier 1 screening and the Tier 2 testing is to identify the impacts on the endocrine system and to characterize the adverse effects to aquatic animals by endocrine disrupting chemicals detected in the aquatic environment in Japan. For the consistent assessment of the effects on reproduction associated with estrogenic, anti-estrogenic, androgenic, and/or anti-androgenic activities of chemicals throughout Tier 1 screening to Tier 2 testing, a unified test species, Japanese medaka (Oryzias latipes), has been used. For Tier 1 screening, the in vivo Fish Short-Term Reproduction Assay (OECD test guideline No. 229) was conducted for 17 chemicals that were nominated based on the results of environmental monitoring, existing knowledge obtained from a literature survey, and positive results in reporter gene assays using the estrogen receptor of Japanese medaka. In the 17 assays using Japanese medaka, adverse effects on reproduction (i.e., reduction in fecundity and/or fertility) were suggested for 10 chemicals, and a significant increase of hepatic vitellogenin in males, indicating estrogenic (estrogen receptor agonistic) potency, was found for eight chemicals at the concentrations in which no overt toxicity was observed. Based on these results, and the frequency and the concentrations detected in the Japanese environment, estrone, 4-nonylphenol (branched isomers), 4-tert-octylphenol, triphenyl phosphate, and bisphenol A were considered as high priority candidate substances for the Tier 2 testing.