Sex-dependent impact of a short rest after lunch on hemodynamics as assessed by Doppler sonography.

PURPOSE: Taking a short rest after lunch suppresses increases in blood flow to the digestive organs and maintains blood flow to the brain in the afternoon, possibly providing beneficial effects in preventing post-prandial drowsiness. The present study investigated sex-dependent influences on changes in hemodynamics produced by taking a short rest after lunch. METHODS: Subjects comprised 20 healthy young adults (10 men, 10 women; mean age 21 ± 1 years). Doppler sonography was performed to measure blood flow in the superior mesenteric artery (SMA) and common carotid artery (CCA) before and after lunch every hour on each day, with and without a 15-min rest with eyes closed after lunch. Blood pressure and heart rate (HR) were also measured. RESULTS: For both men and women, peak systolic velocity (PSV) in the SMA was suppressed by taking a rest. PSV in the CCA in men was increased at 0.5 h after lunch in the resting condition but was decreased in the non-resting condition (median 109%, interquartile range [IQR] 102-120% vs. median 98%, IQR 90-107%; P = 0.037). No such differences were observed in women. Although post-prandial increases in HR were observed in women, a similar increase was only found for men in the resting condition. CONCLUSION: An increase in CCA blood flow was observed only in men. The present study suggests that a short rest after lunch could better promote the maintenance of blood flow to the brain in men than in women.

Close relationships between neck and upper-back stiffness and transverse cervical artery flow velocity.

PURPOSE: Neck and upper-back stiffness is encountered in daily life, with symptoms appearing as dullness or aches predominantly in the trapezius muscle (TM). Our previous study demonstrated that TM hardness as measured with a muscle hardness meter correlates well with transverse cervical artery (TCA) flow supplying the TM. Muscle hardness meters, however, cannot measure hardness in the TM alone. Meanwhile, recent advances in ultrasound elastography have enabled the evaluation of localized hardness in targeted tissues. The present study, therefore, aimed to clarify the relationship between TM hardness as measured by elastography and TCA hemodynamics as measured on Doppler sonography, with reference to daily symptoms of upper-back stiffness. METHODS: The study population comprised 66 healthy young adults (32 males, 34 females; mean age, 21 ± 1 years). Relationships were evaluated between TM hardness as a negative correlate of strain ratio from elastography and TCA hemodynamics on Doppler sonography. Hemodynamics in the TCA were evaluated according to the frequency of neck and upper-back stiffness. RESULTS: TM strain ratio correlated with peak systolic velocity (PSV) in the TCA (r = 0.273, p = 0.036), particularly in symptomatic subjects (r = 0.417, p = 0.022). PSV in the TCA decreased with increasing frequency of daily symptoms (p = 0.045). CONCLUSION: TCA hemodynamics correlated with muscle hardness when evaluating localized TM hardness. This relationship and low PSV in the TCA were evident in symptomatic subjects. These results suggest that PSV in the TCA is associated with neck and upper-back stiffness.

Plasma free amino acid profiles are associated with serum high molecular weight adiponectin levels in Japanese medical check-up population without type 2 diabetes mellitus.

To prevent the progression of type 2 diabetes mellitus (T2DM), early detection and intervention are important. Several studies have already shown that the serum adiponectin level could be useful for evaluating the future risk of T2DM. Recently, plasma free amino acid (PFAA) concentrations have also emerged as potential biomarkers that predict the future onset of T2DM. In this study, we aimed to further characterise PFAA profiles by elucidating the association with the serum high molecular weight (HMW) adiponectin level in this cross-sectional study. A total of 1000 Japanese subjects who underwent medical check-ups were enrolled, and their plasma concentrations of 21 amino acids and clinical parameters were measured. The subjects without T2DM were divided into quartiles (Q1-4) by serum HMW adiponectin level, and the association with between PFAA concentrations was analysed. Concentrations of glutamate, alanine, proline, tyrosine, histidine, methionine, lysine, branched-chain amino acids (BCAAs) and tryptophan varied significantly according to the adiponectin quartile. Furthermore, serum adiponectin levels showed significant inverse correlations with these amino acids. The change in the PFAA profile in the group with the lowest adiponectin concentrations (Q1) was similar to that of T2DM patients. Although both adiponectin levels and PFAA concentrations are known to be altered by the accumulation of visceral fat and insulin resistance, the levels of glutamate, BCAA, lysine and tryptophan remain significantly associated with adiponectin level after adjustment for age, body mass index and homeostasis model assessment of insulin resistance, showing the direct association between PFAA concentrations and the serum HMW adiponectin level. Registration number: University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) UMIN000029920, registered on Nov 13th 2017 (prospectively registered).

Microsatellite instability in the high-grade dysplasia component of duodenal adenoma is associated with progression to adenocarcinoma.

PURPOSE: We examined the microsatellite instability of duodenal tumors to evaluate their molecular features associated with the adenoma-carcinoma sequence. METHODS: Fifty-two non-ampullary duodenal epithelial tumors collected by endoscopic mucosal resection or surgical resection were studied. When a tumor had two or more dysplasia grades, the highest grade was considered. Representative areas were macro-dissected and subjected to a microsatellite instability analysis and immunohistochemical staining. RESULTS: The 52 tumors were classified as either adenoma with low-grade dysplasia (n = 18), adenoma with high-grade dysplasia (n = 20), or adenocarcinomas (n = 14). Among these, 3 adenocarcinoma cases showed microsatellite instability and the remaining 49 tumors showed microsatellite stability. Of the 14 adenocarcinoma cases, 3 contained both high-grade dysplasia and adenocarcinoma components, and 11 contained only the adenocarcinoma component. Interestingly, all three adenocarcinoma + high-grade dysplasia cases were microsatellite instability-high in both the adenocarcinoma and high-grade dysplasia components. Immunohistochemical staining of mismatch repair proteins showed mismatch repair deficiency in three microsatellite instability-high adenocarcinoma + high-grade dysplasia cases. CONCLUSIONS: Only adenocarcinoma cases with high-grade dysplasia components were microsatellite instability-high (in both the adenocarcinoma and high-grade dysplasia components). This suggests that microsatellite instability in the high-grade dysplasia component of duodenal adenoma is associated with progression to adenocarcinoma.

Possible effects of short rest after lunch on hemodynamics in the afternoon.

PURPOSE: Drowsiness is often experienced in the afternoon after lunch. Decreases in blood flow to the brain secondary to increases in blood flow to the digestive organs after food intake could represent an underlying cause. As various beneficial effects of short rests on mental activities have been reported, the present study investigated hemodynamics using Doppler sonography of the common carotid artery (CCA) and superior mesenteric artery (SMA) after lunch, comparing resting and non-resting cases. METHODS: Subjects comprised 24 healthy young adults (10 men, 14 women; mean age 22 ± 1 years). Sonography was performed to measure blood flow before and after lunch on each day, with and without a 15-min lying rest with eyes closed after lunch in each subject. RESULTS: The timing of the peak velocity-time integral in the SMA in resting cases was delayed to 1.5 h after lunch compared to 0.5 h in non-resting cases. Although end-diastolic velocity in the CCA decreased after lunch, this decrease was suppressed in resting cases compared to non-resting cases even 4.5 h after lunch (median 96%, interquartile range [IQR] 83-102% vs. median 87%, IQR 77-92%; P = 0.037). Mean velocity (MV) in the CCA maintained unchanged after lunch in resting cases (P = 0.318), whereas non-resting cases showed decreased MV after lunch (P < 0.001). CONCLUSION: These findings suggest that a short lying rest with eyes closed suppresses increases in blood flow to the digestive organ and maintains blood flow to the brain after lunch. These hemodynamic changes might help explain the benefits of afternoon rests.

First description of Lachnoanaerobaculum orale as a possible cause of human bacteremia.

Lachnoanaerobaculum spp. is an obligate anaerobic, gram-positive, spore-forming, rod-shaped bacillus. Here, we report the first known case of bacteremia due to L. orale, which was detected in a patient with acute lymphoblastic leukemia. A 69-year-old man developed neutropenic fever with severe stomatitis during chemotherapy for leukemia. The bacteria strain isolated from blood culture was successfully identified as L. orale via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Susceptibility testing revealed that the strains showed low minimum inhibitory concentrations (MICs) of beta-lactams, clindamycin, and metronidazole, but higher MICs of fluoroquinolones. The present case study indicates that Lachnoanaerobaculum can be a cause of human infection, including bloodstream infection.

Development of a novel ß-1,6-glucan-specific detection system using functionally-modified recombinant endo-ß-1,6-glucanase.

ß-1,3-d-Glucan is a ubiquitous glucose polymer produced by plants, bacteria, and most fungi. It has been used as a diagnostic tool in patients with invasive mycoses via a highly-sensitive reagent consisting of the blood coagulation system of horseshoe crab. However, no method is currently available for measuring ß-1,6-glucan, another primary ß-glucan structure of fungal polysaccharides. Herein, we describe the development of an economical and highly-sensitive and specific assay for ß-1,6-glucan using a modified recombinant endo-ß-1,6-glucanase having diminished glucan hydrolase activity. The purified ß-1,6-glucanase derivative bound to the ß-1,6-glucan pustulan with a KD of 16.4 nm We validated the specificity of this ß-1,6-glucan probe by demonstrating its ability to detect cell wall ß-1,6-glucan from both yeast and hyphal forms of the opportunistic fungal pathogen Candida albicans, without any detectable binding to glucan lacking the long ß-1,6-glucan branch. We developed a sandwich ELISA-like assay with a low limit of quantification for pustulan (1.5 pg/ml), and we successfully employed this assay in the quantification of extracellular ß-1,6-glucan released by >250 patient-derived strains of different Candida species (including Candida auris) in culture supernatant in vitro We also used this assay to measure ß-1,6-glucan in vivo in the serum and in several organs in a mouse model of systemic candidiasis. Our work describes a reliable method for ß-1,6-glucan detection, which may prove useful for the diagnosis of invasive fungal infections.

Extent of disease affects the usefulness of fecal biomarkers in ulcerative colitis.

BACKGROUND: Fecal biomarkers are considered to be useful surrogate markers for endoscopic activity. Given the mechanisms of fecal biomarkers, we hypothesized that the extent of ulcerative colitis (UC; pancolitis, left-sided colitis, and proctitis) could affect the usefulness of fecal biomarkers for assessing endoscopic and clinical disease activity; however, few studies have evaluated the utility of fecal biomarkers in the disease extent of UC. METHODS: Fecal calprotectin, a fecal immunochemical test for hemoglobin, and fecal lactoferrin were used as fecal biomarkers. UC patients, who underwent colonoscopy within 30 days of the fecal biomarker test, participated in this observational study. Clinical and endoscopic disease activity was assessed using the Lichtiger Index and Mayo endoscopic subscore (MES), respectively. RESULTS: A total of 162 colonoscopies were performed on 133 UC patients. A correlation analysis between each biomarker and the MES for each disease-extent subgroup showed a decreased correlation in the proctitis compared with the other groups. With the exception of proctitis, it was possible to distinguish between MES 0 and MES ≥ 1 with high area-under-the-curve values for fecal calprotectin and fecal lactoferrin. The fecal immunochemical test for hemoglobin was superior at discriminating MES 0 for proctitis. CONCLUSIONS: For the practical application of fecal biomarkers for UC patients, it is necessary to consider disease extent before use. In particular, patients with proctitis exhibit a low correlation between stool biomarkers and endoscopic findings. The usefulness of these biomarkers for endoscopic remission is reduced, except for the fecal immunochemical test for hemoglobin.

A case of infective endocarditis caused by "Neisseria skkuensis".

"Neisseria skkuensis" is a gram-negative coccus that is endemic in the human oral cavity, with only few reports of infection in humans. Herein, we report a case of a male patient in his sixties presenting with infective endocarditis (IE) caused by "N. skkuensis". To our knowledge, this is the second case of IE confirmed using 16S rRNA gene to have been caused by "N. skkuensis". The accurate diagnosis of rare or difficult-to-identify pathogens is a major challenge for clinical microbiological laboratories. Although Neisseria spp. are common in the oral cavity and are often seen in routine tests, identification of their biochemical properties and mass spectrometric analysis are difficult. In this case report, we describe the accurate identification of "N. skkuensis" by 16S rRNA gene sequencing analysis compared to other identification methods. Further cases of "N. skkuensis" are needed to fully evaluate the clinical approach of this detection method.

Establishing an internal quality control method for the stable extraction of nucleic acids of severe acute respiratory syndrome coronavirus 2 and RT-PCR-based detection.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the coronavirus disease 2019 (COVID-19), is detected using real-time RT-PCR. However, there are limitations pertaining to quality control, particularly with respect to establishing quality control measures for extraction of viral nucleic acids. Here, we investigated the quality control measures for the various processes using an extrinsic quality control substance and quality control charts. METHODS: An extrinsic quality control substance was added to the sample, and then, real-time RT-PCR was performed. Samples with negative test results and the corresponding data were analyzed; a quality control chart was created and examined. RESULTS: Data analysis and the quality control charts indicated that SARS-CoV-2 could be reliably detected using real-time RT-PCR, even when different nucleic acid extraction methods were used or when different technicians were employed. CONCLUSION: With the use of quality control substances, it is possible to achieve quality control throughout the process-from nucleic acid extraction to nucleic acid detection-even upon using varying extraction methods. Further, generating quality control charts would guarantee the stable detection of SARS-CoV-2.

Coronary Vasculitis Induced in Mice by the Cell Wall Mannoprotein of Candida krusei.

Kawasaki disease (KD) is an inflammatory disease that was identified by Professor Tomisaku Kawasaki in 1961. Candida albicans-derived substances, such as the hot water extract of C. albicans (CADS) and Candida water-soluble fraction (CAWS), induced coronary vasculitis similar to KD in mice. An increasing proportion of deep-seated candidiasis cases are caused by non-albicans Candida and are often resistant to antifungal drugs. We herein investigated whether the hot water extract of C. krusei, inherently resistant to fluconazole, induces vasculitis in mice. Three strains of C. krusei, NBRC1395, NBRC1162, and NBRC10737, were cultured in natural (Y) and chemically defined (C) media and cell wall mannoprotein (MN) fractions were prepared by autoclaving cells (CKY1395MN, CKC1395MN, CKY1162MN, CKC1162MN, CKY10737MN, and CKC10737MN). All MN fractions reacted strongly with Concanavalin A (Con A) and dectin-2 and induced anaphylactoid shock in ICR mice. MNs induced severe coronary vasculitis in DBA/2 mice, resulting in cardiac hypertrophy. MNs also induced coronary vasculitis in C57Bl/6 mice. These results suggest that the MNs of non-albicans Candida, such as C. krusei, induce similar toxicity to those of C. albicans.

APC:T1556fs and STK11 mutations in duodenal adenomas and adenocarcinomas.

PURPOSE: Duodenal adenoma and adenocarcinoma (AC) are rare tumors, and few studies have examined their genetic features. We aimed to determine the key genetic changes in duodenal adenoma and AC, and to clarify the possible involvement of the adenoma-carcinoma sequence in duodenal tumor carcinogenesis. METHODS: Nineteen duodenal tumors collected by endoscopic mucosal resection or surgical resection were classified as AC, adenoma with high-grade dysplasia (HGD), or adenoma with low-grade dysplasia (LGD) per the World Health Organization tumor classification. When a tumor contained two or more components with different dysplasia grades, the highest grade was assigned as the tumor grade. Representative areas of these components with different grades were microdissected and evaluated by a genomic analysis. Mutational hotspots involving 50 oncogenes and tumor suppressor genes were analyzed by next-generation sequencing, and their association with the dysplasia grade was investigated. RESULTS: We analyzed 27 tumor components of AC or adenoma, with 11 normal mucosal samples obtained from 19 patients with duodenal tumors. The most prevalent abnormality among 50 genes tested was the KRAS mutation, which was detected in 12/19 (63.2%) patients, followed by APC and TP53 mutations (47.4 and 36.8%, respectively). According to the tumor dysplasia grading of each component, KRAS mutations were found in 5/8 (62.5%) tumors with AC components, 6/9 (66.7%) tumors with HGD components, and 3/10 (30.0%) tumors with LGD components. TP53 mutations were found in 4/8 (50.0%) tumors with AC components, 3/9 (33.3%) tumors with HGD components, and 1/10 (10.0%) tumors with LGD components. APC mutations were found in 2/8 (25.0%) tumors with AC components, 6/9 (66.7%) tumors with HGD components, and 5/10 (50.0%) tumors with LGD components. Notably, an APC:T1556fs mutation was detected in six cases (31.6%), five of which were adenoma cases. Furthermore, STK11 mutations were confirmed in 2/8 (25.0%) AC cases and in 1/11 (9.1%) adenoma cases. CONCLUSION: APC:T1556fs and STK11 mutations found in duodenal adenomas/ACs highlight the importance of proteins encoded by these genes in tumor development. APC mutations were identified in duodenal adenomas more frequently than in duodenal ACs, which differed from the observations of typical adenoma-carcinoma sequences seen in colorectal cancer, suggesting the limited involvement of this mechanism in duodenal cancer development.

Preoperative evaluation of intraoperative blood loss during malignant soft tissue tumor resection by ultrasonography.

BACKGROUND: Preoperative evaluation of the risk of surgery-related blood loss in malignant soft tissue tumor resection is difficult because of wide variations in histological subtype, malignancy, location, and size. Ultrasonography is useful for the evaluation of blood flow around a soft tissue tumor and has the potential to preoperatively estimate intraoperative blood loss in tumor resection. To date, there has been no report regarding blood loss evaluation using ultrasonography in this field. PATIENTS AND METHODS: The usefulness of information obtained by ultrasonography, including tumor size, vessel density in the tumor, and blood flow volume in the vessels, was analyzed for the prediction of intraoperative blood loss in malignant soft tissue tumor resection. RESULTS: Vessel density in the tumor and blood flow in the vessels were identified as independent risk factors for blood loss. Using these factors, a new index for the prediction of blood loss was established. Receiver operating characteristic analyses revealed a high area under the curve value (0.80), confirming the accuracy of the index for the prediction of blood loss. CONCLUSION: Ultrasonography is a useful modality for predicting intraoperative blood loss in malignant soft tissue tumor surgery.

Relationship between epicardial adipose tissue thickness and early impairment of left ventricular systolic function in patients with preserved ejection fraction.

Epicardial adipose tissue (EAT) is metabolically bioactive fat. The present study aimed to clarify the relationship between EAT amount and early impairment of left ventricular (LV) systolic function in patients with preserved ejection fraction (EF), all evaluated echocardiographically. Participants comprised 62 elderly women (mean age ± standard deviation, 68 ± 11 years) with lifestyle-related diseases and EF ≥ 60 %. EAT amount was evaluated as thickness. Parameters suggesting early impairment of systolic function such as decreases in systolic mitral annular velocity (S') and tissue mitral annular displacement percentage (TMAD %) were evaluated along with EF. Correlations between EAT thickness and these LV systolic functions were assessed. Influences of various factors on the resultant significant relationships were also assessed. EAT thickness correlated inversely with S' and TMAD % (r = -0.402, p = 0.001 and r = -0.585, p < 0.001, respectively), but did not correlate with EF (r = 0.054, not significant). These significant relationships were maintained after considering factors such as body mass index, age, presence of lifestyle-related diseases and blood test results. A significant relationship existed between EAT amount and early impairment of LV systolic function in patients with preserved EF. Accumulation of EAT might contribute to the initial development of LV systolic dysfunction.

Relationship between Pericardial Adipose Tissue Thickness and Early Impairment of Left Ventricular Function, Both Evaluated on Echocardiography.

Epicardial adipose tissue (EAT) is metabolically bioactive, and accumulation of this tissue is related to early impairment of left ventricular (LV) systolic function as well as diastolic function. However, pericardial adi- pose tissue (PAT), located outside the EAT, has recently been demonstrated to be more closely associated with metabolic risk factors than EAT. The present study aimed to clarify whether PAT thickness is related to early impairment of LV function in a similar manner to EAT thickness, with both evaluated echocardio- graphically. Subjects were 49 women (mean age, 68ill years) composed of both patients with metabolic diseases and those with other diseases, and ejection fraction (EF) >55%. Systolic function was assessed by measuring EF, systolic mitral annular velocity (S'), and tissue mitral annular displacement percentage (TMAD%). Diastolic function was assessed by measuring early rapid filling wave velocity (E)/late filling wave velocity due to atrial contraction (A) ratio (E/A), peak early diastolic mitral annular velocity (e'), and E/e' ratio. Correlations between EAT or PAT thickness and LV systolic or diastolic function were assessed. EAT thickness correlated with S' and TMAD%(r=-0.399, p=0.005 and r=-0.570, p<0.001, respective- ly), but not with EF. However, PAT thickness was not correlated with any of these. EAT thickness corre- lated with E/A, e' and E/e'(r=-0.382, p=0.007; r=-0.493, p<0.001; and r=0.331, p=0.020, respective- ly). Again, PAT thickness was not correlated with any of these. PAT thickness appears unrelated to early impairment of LV function.

[Study on the Sample Preservation Temperature and Period in Circulating MicroRNA Quantification Using Spike-In Control].

MicroRNA in body fluid is called circulating microRNA and is expected to be a non-invasive stable biomarker of various diseases. In real-time RT-PCR of circulating microRNA, synthetic non-human microRNA, such as cel-miR-39, is used as spike-in control RNA instead of endogenous control RNA. Spike-in control RNA, which is added into sera or plasma just before RNA extraction, does not reflect microRNA degradation in the period between blood sampling and RNA extraction. Therefore, it is essential to prevent degradation of circulating microRNA in this period for better reproducibility of the quantification of microRNA using spike-in control. To address this issue, we analyzed the stability of cel-miR-39 on ice and circulating miR-21 and miR-223 in whole blood and serum. The synthetic cel-miR-39 in RNase-free water was stable for at least 3 hours on ice. Degradation of miR-21 and miR-223 in whole blood was not observed for 3 hours at room temperature. However, miR-223 in serum was apparently degraded within 24 hours at 4°C and the stability levels of miR-21 and miR-223 in serum were significantly different (fold changes of miR-21 and miR- 223 within 24 hours were 0.891 and 0.485, respectively). These results show that it is essential to avoid long-term storage of sera at 4°C to prevent degradation of microRNA in the quantification of circulating microRNA using spike-in control.

A psoas abscess caused by Propionibacterium propionicum.

Pelvic actinomycosis-like disease due to Propionibacterium propionicum has been very rare and only a few cases have been reported in the literature. We herein report a probable first case of a psoas abscess caused by P. propionicum. Since P. propionicum is indistinguishable from Actinomyces israelii by morphological features or routine biochemical tests, 16S rRNA gene sequencing was useful to discriminate these two species in this case.

Detection of decreased granules in neutrophils by automated hematology analyzers XR-1000 and UniCel DxH 800.

OBJECTIVE: This study aimed to investigate the utility of neutrophil-related cell population data obtained by automated hematology analyzers in assessing myelodysplastic syndrome cases with decreased granules in neutrophils. METHODS: A total of 108 subjects were classified into normal granule (n = 35), hypogranulation (n = 37), or hypergranulation (n = 36) groups. Neutrophil cell area and granule area were measured by ImageJ. All samples were analyzed on the XR-1000 and UniCel DxH 800, and neutrophil-related parameters were compared among the 3 groups. RESULTS: Neutrophil cell area and the ratio of the granular area showed significant differences among the 3 groups; they were the highest in the hypergranulation group and lowest in the hypogranulation group. XR-1000 data showed significant differences in NE-SFL and NE-FSC among the 3 groups (P < .0001). NE-SFL and NE-FSC discriminated most accurately hypogranulation group against other groups. UniCel DxH 800 data showed significant differences in MN-V-NE, MN-MALS-N, MN-UMALS-NE, SD-UMALS-NE (P <.01), MN-LMALS-NE, and SD-LMALS-NE (P <.05) among the 3 groups. The combination of SD-V-NE and SD-LMALS-NE discriminated most accurately the hypogranulation group against the other groups. CONCLUSION: NE-SFL and NE-FSC and the combination of SD-V-NE and SD-LMALS-NE are useful in detecting cases with decreased granules in neutrophils.

A rad50 germline mutation induces tumorigenesis and ataxia-telangiectasia phenotype in a transparent medaka model.

The MRE11A-RAD50-NBS1 complex activates the ataxia-telangiectasia mutated (ATM) pathway and plays a central role in genome homeostasis. The association of RAD50 mutations with disease remains unclear; hence, we adopted a medaka rad50 mutant to demonstrate the significance of RAD50 mutation in pathogenesis using the medaka as an experimental animal. A 2-base pair deletion in the rad50 gene was introduced into transparent STIII medaka using the CRISPR/Cas9 system. The mutant was analyzed histologically for tumorigenicity and hindbrain quality, as well as for swimming behavior, to compare with existing ATM-, MRE11A-, and NBS1-mutation-related pathology. Our results revealed that the medaka rad50 mutation concurrently reproduced tumorigenesis (8 out of 10 rad50Δ2/+ medaka), had a decrease in median survival time (65.7 ± 1.1 weeks in control vs. 54.2 ± 2.6 weeks in rad50Δ2/+ medaka, p = 0.001, Welch's t-test), exhibited semi-lethality in rad50Δ2/Δ2 medaka and most of the major ataxia-telangiectasia phenotypes, including ataxia (rheotaxis ability was lower in rad50Δ2/+ medaka than in the control, Mann-Whitney U test, p < 0.05), and telangiectasia (6 out of 10 rad50Δ2/+ medaka). The fish model may aid in further understanding the tumorigenesis and phenotype of ataxia-telangiectasia-related RAD50 germline mutations and in developing novel therapeutic strategies against RAD50 molecular disorders.