Prostatic stromal tumour of uncertain malignant potential in a dog.

An 11-year-old male Miniature Dachshund dog was presented with dyschezia. Computed tomography examination 35 days after the initial visit revealed a prostate mass (4.0 × 3.5 × 2.7 cm) and prostatectomy and orchiectomy were performed 13 days later. Grossly, the prostate was rubbery and the cut surface of the mass was swollen. The mass was whitish and demarcated from the surrounding tissues. Microscopically, the mass had a capsulate consisting of atypical spindloid stromal cells arranged in a phyllode pattern and also in a fasciculated pattern admixed with acinar ductal cells. Atypical stromal cells contained round-to-oval finely hyperchromatic nuclei that had distinct nuclei and abundant eosinophilic cytoplasm. Immunohistochemically, the atypical stromal cells were positive for vimentin, CD34, desmin, α-smooth muscle actin, progesterone receptor and androgen receptor but negative for cytokeratin AE1/AE3, p63, c-Kit, DOG-1 and SOX10. On the basis of these findings, the tumour was diagnosed as a prostatic stromal tumour of uncertain malignant potential.

Dendritic cell vaccination in combination with erlotinib in a patient with inoperable lung adenocarcinoma: a case report.

BACKGROUND: Satisfactory treatment for patients with unresectable advanced lung cancer has not yet been established. We report a case of unresectable advanced lung cancer (stage IIIb: T2aN3M0) treated with a total of 15 doses of dendritic cells pulsed with a Wilms' tumor 1 and mucin 1 vaccine in combination with erlotinib, a small molecule epidermal growth factor receptor tyrosine kinase inhibitor, for more than 699 days without recurrence or metastasis. CASE PRESENTATION: A 63-year-old Korean woman was diagnosed with lung adenocarcinoma by pathology and computed tomography. The adenocarcinoma showed an epidermal growth factor receptor (EGFR) mutation, no anaplastic lymphoma kinase expression, and less than 1% expression of programmed death ligand 1. She received erlotinib alone for approximately 1 month. She then received erlotinib and the dendritic cells pulsed with Wilms' tumor 1 and mucin 1 vaccine. The diameter of the erythema at the vaccinated sites was 30 mm at 48 hours after the first vaccination. Moreover, it was maintained at more than 20 mm during the periods of vaccination. These results suggested the induction of antitumor immunity by the vaccine. Remarkably, the tumor size decreased significantly to 12 mm, a 65.7% reduction, after combined therapy with eight doses of the dendritic cells pulsed with Wilms' tumor 1 and mucin 1 vaccine and erlotinib for 237 days based on fluorodeoxyglucose uptake by positron emission tomography/computed tomography and computed tomography. Interestingly, after 321 days of combination therapy, the clinical findings improved, and no tumor was detected based on computed tomography. Validation of the tumor's disappearance persisted for at least 587 days after treatment initiation, without any indication of recurrence or metastasis. CONCLUSION: Standard anticancer therapy combined with the dendritic cells pulsed with Wilms' tumor 1 and mucin 1 vaccine may have therapeutic effects for such patients with unresectable lung adenocarcinoma.

Gene expression profiling of pancreatic neuroendocrine carcinoma and mixed neuroendocrine-non-neuroendocrine neoplasm.

Pancreatic neuroendocrine carcinoma (NEC) and mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) are rare pancreatic malignant tumors, and comprehensive gene analyses are scarce. In this study, six NECs and six MiNENs were collected, immunohistochemistry for synaptophysin, chromogranin A, INSM1, Ki-67, and Rb was conducted, and KRAS mutational status was examined. Among these cases, comprehensive gene expression analysis of oncogene pathways using nCounter® were performed with six NECs and four MiNENs, and those data were compared with that of three pancreatic ductal adenocarcinomas (PDACs), with that of three normal pancreatic ducts, and with each other. By dividing NEC and MiNEN cases into KRAS-mutated group and KRAS-wild group, the difference of clinicopathological data and gene expression profiling data were examined between the two groups. Compared to the data of normal pancreatic epithelium, all 13 cancer-related pathways were upregulated in PDAC, MiNEN, and NEC group with more upregulation in this order. Compared to the data of PDAC, genes of DNA Damage repair pathway was most upregulated both in NECs and MiNENs. Regarding the difference between KRAS-mutated and KRAS-wild groups, several genes were differentially expressed between the two, where MMP7 was the upregulated gene with highest p-value and NKD1 was the downregulated gene with highest p-value in KRAS-mutated group. From the extent of upregulation of 13 pathways, MiNEN was considered more progressed stage than PDAC, and NEC was considered more progressed than MiNEN. From the comparison of KRAS-mutated and KRAS-wild NECs and MiNENs, several differentially expressed genes were identified in this study.

Comparison of guidewires for successful cannulation of biliary stenosis and targeting of biliary branches in ERCP.

Background and study aims Guidewires play a crucial role in endoscopic retrograde cholangiopancreatography. The ability to pass through stenosis, and the ability to seek the desired biliary branch are particularly important. In this study, we aimed to compare these specific abilities in various guidewires by using a bile duct model. Patients and methods Seven 0.025-inch angle-type guidewires (VisiGlide2, Fielder 25, EndoSelector, NaviPro, Jagwire Plus, RevoWave DualMaster, and J-WIRE prologue ST) were evaluated. To compare these, a bile duct silicone model was prepared. The time from the entry of the guidewire into the common bile duct with the stenosis to the emergence of the guidewire from the common bile duct after reaching two target intrahepatic bile duct branches was measured. Results VisiGlide 2 and Fielder 25 were the fastest guidewires, whereas Jagwire Plus was the slowest. Conclusions In this study, a guidewire with a tip deflection height of approximately 9 mm and a hydrophilic coating length of 7 to 8 cm achieved the fastest completion time for the course. In clinical practice, it is important to consider the performance required in various scenarios and to select the most appropriate guidewire. The results of this model test, which focused on the time required to complete the course around the model, can serve as a foundation for guidewire selection. This method holds potential utility in future guidewire development.

Sphincter of Oddi dysfunction that could not be diagnosed with Rome IV: a case report.

A 30-year-old female patient presented with monthly episodes of severe intermittent upper abdominal pain, especially after consuming fatty meals. Over a period of 5 years, she visited the emergency department 21 times due to the intensity of the pain. Although the pain appeared consistent with biliary pain, both blood and imaging tests showed no abnormalities. Despite not meeting the Rome IV criteria, we suspected sphincter of Oddi dysfunction (SOD). To further investigate, we conducted hepatobiliary scintigraphy (HBS), which revealed a clear delay in bile excretion. With the patient's informed consent, we performed endoscopic sphincterotomy (EST) and as of 10 months later, there have been no recurrences. This case demonstrates an instance of SOD that could not be diagnosed using the Rome IV criteria alone but was successfully identified through HBS. It underscores the possibility of hidden cases of SOD among patients who regularly experience severe epigastric pain, where routine blood or imaging tests may not provide a diagnosis. HBS may be a useful non-invasive test in confirming the presence of previously undiagnosed SOD. As SOD can be easily treated with EST, updating the current diagnostic criteria to include such types of SOD should be considered in the future.

The spatiotemporal electrogram dispersion ablation targeting rotors is more effective for elderly patients than non-elderly population.

Background: Modulating atrial fibrillation (AF) drivers has been proposed as one of the effective ablation strategies for non-paroxysmal AF (non-PAF). However, the optimal non-PAF ablation strategy is still under debate because the exact mechanisms of AF persistence including focal activity and/or rotational activity, are not well-understood. Recently, spatiotemporal electrogram dispersion (STED) assumed to indicate rotors in the form of rotational activity is proposed as an effective target for non-PAF ablation. We aimed to clarify the effectiveness of STED ablation for modulating AF drivers. Methods: STED ablation plus pulmonary vein isolation was applied in 161 consecutive non-PAF patients not undergoing previous ablation. STED areas within the entire left and right atria were identified and ablated during AF. After the procedures, the STED ablation's acute and long-term outcomes were investigated. Results: (1) Despite a more effective acute outcome of the STED ablation for both AF termination and non-inducibility of atrial tachyarrhythmias (ATAs), Kaplan-Meier curves showed that the 24-month freedom ratio from ATAs was 49%, which resulted from the higher recurrence ratio of atrial tachycardia (AT) rather than AF. (2) A multivariate analysis showed that the determinant of ATA recurrences was only a non-elderly age, not long-standing persistent AF, and an enlarged left atrium, which were conventionally considered as key factors. Conclusions: STED ablation targeting rotors was effective in elderly non-PAF patients. Therefore, the main mechanism of AF persistency and the component of the fibrillatory conduction might vary between elders and non-elders. However, we should be careful about post-ablation ATs following substrate modification.

Clinical utility of the "balloon lever technique" in the right inferior pulmonary vein cryoballoon ablation.

Background: The acute success rate of pulmonary vein isolation (PVI) with cryoballoon (CB) is reported to be lower in the right inferior pulmonary vein (RIPV). This study aimed to investigate the utility of the "balloon lever technique (BLT)" for RIPV CB ablation. Methods: We retrospectively studied consecutive patients who underwent CB-PVI for atrial fibrillation between February 21, 2020 and June 3, 2022. RIPV cryoablation was performed according to a specific protocol. The patients underwent RIPV cryoablation using the conventional method. If the method was found ineffective, BLT cryoablation was performed. The acute success rate of RIPV CB ablation was examined. We also investigated the RIPV isolation rate and procedural parameters during conventional and BLT cryoablation. Results: Ninety-three patients were included in the analysis. RIPV isolation was achieved in 89.2% (83/93) of the patients using conventional method and subsequent BLT cryoablation. Meanwhile, 68 patients underwent BLT cryoablation because the conventional method was ineffective. RIPV was isolated with BLT in 85.3% (58/68) of patients. Additionally, BLT was found to be superior to conventional cryoablation in terms of nadir balloon temperature, freezing time, and thawing time to a specific temperature in patients who underwent both conventional and BLT cryoablations. Conclusions: BLT is useful in RIPV cryoablation when the conventional method is ineffective. BLT cryoablation may be helpful, mainly because of the BLT-mediated contact of the balloon with the bottom of the RIPV, which leads to optimal RIPV occlusion.

Establishment of a BRAF V595E-mutant canine prostate cancer cell line and the antitumor effects of MEK inhibitors against canine prostate cancer.

Canine prostate cancer (cPCa) is a malignant neoplasm with no effective therapy. The BRAF V595E mutation, corresponding to the human BRAF V600E mutation, is found frequently in cPCa. Activating BRAF mutations are recognized as oncogenic drivers, and blockade of MAPK/ERK phosphorylation may be an effective therapeutic target against BRAF-mutated tumours. The aim of this study was to establish a novel cPCa cell line and to clarify the antitumor effects of MEK inhibitors on cPCa in vitro and in vivo. We established the novel CHP-2 cPCa cell line that was derived from the prostatic tissue of a cPCa patient. Sequencing of the canine BRAF gene in two cPCa cell lines revealed the presence of the BRAF V595E mutation. MEK inhibitors (trametinib, cobimetinib and mirdametinib) strongly suppressed cell proliferation in vitro, and trametinib showed the highest efficacy against cPCa cells with minimal cytotoxicity to non-cancer COPK cells. Furthermore, we orally administered 0.3 or 1.0 mg/kg trametinib to CHP-2 xenografted mice and examined its antitumor effects in vivo. Trametinib reduced tumour volume, decreased phosphorylated ERK levels, and lowered Ki-67 expression in xenografts in a dose-dependent manner. Although no clear adverse events were observed with administration, trametinib-treated xenografts showed osteogenesis that was independent of dosage. Our results indicate that trametinib induces cell cycle arrest by inhibiting ERK activation, resulting in cPCa tumour regression in a dose-dependent manner. MEK inhibitors, in addition to BRAF inhibitors, may be a targeted agent option for cPCa with the BRAF V595E mutation.

COVID-19 vaccination benefits in preventing severe disease in mild-to-moderate cases: An analysis in the first specialized hospital for COVID-19 in Japan.

BACKGROUND: In Japan, the fourth round of coronavirus disease (COVID-19) vaccination is ongoing and is targeted at medical staff and nursing home workers, individuals aged ≥60 years, and those with comorbidities or other high-risk factors, including body mass index (BMI) ≥30 kg/m2. The incidence of severe COVID-19 decreased markedly after widespread COVID-19 vaccination drives, and our hospital experienced a similar trend. We, therefore, examined the characteristics of our patients to clarify who benefited the most from vaccination. METHODS: We retrospectively investigated all patients hospitalized for COVID-19 in Osaka City Juso Hospital between March 1, 2021, and June 30, 2022. Using multivariable logistic analysis, we calculated the adjusted odds ratios (aORs) for severe disease after vaccination in the whole dataset and in subsets stratified by age, sex, BMI, smoking history, pre-hospitalization location, and comorbidities. RESULTS: The analysis included 1041 patients. Multivariable logistic analysis showed that vaccination was associated with a low risk of severe disease, with an aOR of 0.21 (95% confidence interval: 0.12-0.36, p < 0.001). On stratifying the analysis according to background characteristics, lower aORs for severe COVID-19 were found for patients aged ≥60 years and for those with diabetes or hypertension. Notably, patients with BMI >30 kg/m2 and those with BMI ≥18 kg/m2 and ≤30 kg/m2 benefited from vaccination. CONCLUSIONS: Individuals with diabetes or hypertension and those of age ≥60 years benefited more from vaccination than did their counterparts. We recommend extending the fourth round of vaccinations to individuals with a BMI of 18-30 kg/m2.

Outcomes in novel hospital-at-home model for patients with COVID-19: a multicentre retrospective cohort study.

BACKGROUND: Hospital-at-home (HaH) care has been proposed as an alternative to inpatient care for patients with coronavirus disease (COVID-19). Previous reports were hospital-led and involved patients triaged at the hospitals. To reduce the burden on hospitals, we constructed a novel HaH care model organized by a team of local primary care clinics. METHODS: We conducted a multicentre retrospective cohort study of the COVID-19 patients who received our HaH care from 1 January to 31 March 2022. Patients who were not able to be triaged for the need for hospitalization by the Health Center solely responsible for the management of COVID-19 patients in Osaka city were included. The primary outcome was receiving medical care beyond the HaH care defined as a composite outcome of any medical consultation, hospitalization, or death within 30 days from the initial treatment. RESULTS: Of 382 eligible patients, 34 (9%) were triaged for hospitalization immediately after the initial visit. Of the remaining 348 patients followed up, 37 (11%) developed the primary outcome, while none died. Obesity, fever, and gastrointestinal symptoms at baseline were independently associated with an increased risk of needing medical care beyond the HaH care. A further 129 (37%) patients were managed online alone without home visit, and 170 (50%) required only 1 home visit in addition to online treatment. CONCLUSIONS: The HaH care model with a team of primary care clinics was able to triage patients with COVID-19 who needed immediate hospitalization without involving hospitals, and treated most of the remaining patients at home.

3D-Printed Fast-Dissolving Oral Dosage Forms via Fused Deposition Modeling Based on Sugar Alcohol and Poly(Vinyl Alcohol)-Preparation, Drug Release Studies and In Vivo Oral Absorption.

Three-dimensional printing technology holds marked promise for the pharmaceutical industry and is now under intense investigation. Most research is aimed at a greater efficiency in printing oral dosage forms using powder bed printing or fused deposition modeling (FDM). Oral dosage forms printed by FDM tend to be hard objects, which reduce the risk of cracking and chipping. However, one challenge in printing oral dosage forms via FDM is achieving rapid drug release, because the materials for FDM are basically thermoplastic polymers with slow drug release properties. In this study, we investigated printing a fast-dissolving oral dosage form by adding sugar alcohol to a poly(vinyl alcohol)-based formulation for FDM. Filaments which contain sugar alcohol were successfully prepared, and objects were printed with them as oral dosage forms by FDM. On drug release testing, a printed oral dosage form in a ring shape which contained 55% maltitol showed a more than 85% drug release in 15 min. In vivo oral absorption of this printed oral dosage form in dogs was comparable to that of a conventional fast-dissolving tablet. Of particular interest, the drug release profile and drug amount of the oral dosage forms can be easily controlled by a change in shape using 3D Computer Aided Design. These characteristics will encourage the prevalence of FDM by the pharmaceutical industry, and contribute to the promotion of personalized medicine.

Ionoacoustic application of an optical hydrophone to detect proton beam range in water.

BACKGROUND: Proton range uncertainty has been the main factor limiting the ability of proton therapy to concentrate doses to tumors to their full potential. Ionoacoustic (IA) range verification is an approach to reducing this uncertainty by detecting thermoacoustic waves emitted from an irradiated volume immediately following a pulsed proton beam delivery; however, the signal weakness has been an obstacle to its clinical application. To increase the signal-to-noise ratio (SNR) with the conventional piezoelectric hydrophone (PH), the detector-sensitive volume needs to be large, but it could narrow the range of available beam angles and disturb real-time images obtained during beam delivery. PURPOSE: To prevent this issue, we investigated a millimeter-sized optical hydrophone (OH) that exploits the laser interferometric principle. For two types of IA waves [γ-wave emitted from the Bragg peak (BP) and a spherical IA wave with resonant frequency (SPIRE) emitted from the gold fiducial marker (GM)], comparisons were made with PH in terms of waveforms, SNR, range detection accuracy, and signal intensity robustness against the small detector misalignment, particularly for SPIRE. METHODS: A 100-MeV proton beam with a 27 ns pulse width and 4 mm beam size was produced using a fixed-field alternating gradient accelerator and was irradiated to the water phantom. The GM was set on the beam's central axis. Acrylic plates of various thicknesses, up to 12 mm, were set in front of the phantoms to shift the proton range. OH was set distal and lateral to the beam, and the range was estimated using the time-of-flight method for γ-wave and by comparing with the calibration data (SPIRE intensity versus the distance between the GM and BP) derived from an IA wave transport simulation for SPIRE. The BP dose per pulse was 0.5-0.6 Gy. To measure the variation in SPIRE amplitude against the hydrophone misalignment, the hydrophone was shifted by ± 2 mm at a maximum in lateral directions. RESULTS: Despite its small size, OH could detect γ-wave with a higher SNR than the conventional PH (diameter, 29 mm), and a single measurement was sufficient to detect the beam range with a submillimeter accuracy in water. In the SPIRE measurement, OH was far more robust against the detector misalignment than the focused PH (FPH) used in our previous study [5%/mm (OH) versus 80%/mm (FPH)], and the correlation between the measured SPIRE intensity and the distance between the GM and BP agreed well with the simulation results. However, the OH sensitivity was lower than the FPH sensitivity, and about 5.6-Gy dose was required to decrease the intensity variation among measurements to less than 10%. CONCLUSION: The miniature OH was found to detect weak IA signals produced by proton beams with a BP dose used in hypofractionated regimens. The OH sensitivity improvement at the MHz regime is worth exploring as the next step.

Relaxin contributes to the elevation of monocytic myeloid-derived suppressor cells in peripheral blood of pregnant canines.

Tolerance towards fetal alloantigens in the maternal immune system is essential for maintaining pregnancy. Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells characterized by their ability to suppress immune activity and maintain maternal-fetal immune tolerance. However, the mechanisms underlying MDSC induction have not been elucidated. Herein, we investigated the myeloid-derived suppressor cells (MDSCs) in the peripheral blood of pregnant canines and its induction mechanism. By analyzing the concentration of MDSCs in the peripheral blood of pregnant canines, elevation of MDSCs has been observed during pregnancy. In addition, MDSCs from pregnant canines inhibit T cell activation. These results suggest that the elevated MDSCs in canine pregnancy may contribute to reduces maternal immune activity. To clarify the cause of MDSCs elevation in canine pregnancy, we analyzed the relationship between pregnancy-related hormones (estradiol, progesterone, and relaxin) and MDSCs. Serum relaxin levels, but not estradiol and progesterone, were correlated with the ratio of monocyte MDSCs. Additionally, relaxin induced monocytic MDSCs as well as inhibited T cell activation in vitro. Therefore, relaxin contributes to the elevation of monocytic MDSCs in the peripheral blood of pregnant canines. Our findings highlight the novel role of relaxin in pregnancy and contribute to a better understanding of maternal-fetal immune tolerance.

Quality of cauda epididymal sperm immediately after collection and after freezing-thawing from Amur leopard cats (Prionailurus bengalensis euptilurus) and a local population of the subspecies Tsushima leopard cats.

In this study, cauda epididymal sperm were collected from Amur leopard cats with various causes of death as well as Tsushima leopard cats that underwent castration surgery, and sperm quality was compared with that in domestic cats. A sufficient number of sperm similar to those in domestic cats could be collected from the cauda epididymis of Amur leopard cats. However, in old leopard cats, no or very few cauda epididymal sperm were recovered, although there were no differences in sperm motility and sperm abnormality. There were no significant differences in sperm quality immediately after collection and after freezing-thawing of cauda epididymal sperm compared with corresponding estimates in domestic cats.

The Double-Max method: a novel method for gallbladder epithelial biopsy.

Video 1A novel biopsy method for gallbladder epithelial biopsy.

A successful treatment of ganglionated plexi ablation for vagally mediated nocturnal atrioventricular block.

Patients suffering from sleep-related bradyarrhythmias are often underdiagnosed, due to the presence of asymptomatic cases. Although the consequence of increased nocturnal parasympathetic nerve activities and decreased sympathetic nerve activity during sleep are associated with nocturnal bradyarrhythmias, the detailed mechanisms are still unknown. It is well known that ganglionated plexi (GP) ablation is an effective therapeutic approach to modify autonomic nerve functions. Here, we report a case of successful treatment for the vagally mediated long ventricular pauses during sleep using autonomic modulation through GP ablation. Learning objective: Sleep-related bradyarrhythmias unrelated to sleep apnea or hypopnea are rare sleep disorders. Treatment of this disorder has not been established. High-frequency stimulation guided ganglionated plexi ablation could be an effective therapeutic approach to achieve long-term vagal attenuation to prevent vagally induced nocturnal bradyarrhythmias.

Ectopic discharge originating from the ostium of the inferior vena cava that is likely to cause atrial fibrillation.

It has been established that the initiation of paroxysmal atrial fibrillation (AF) is frequently associated with ectopic beats inside the thoracic veins, including the pulmonary veins, superior vena cava, coronary sinus, and/or vein of Marshall. However, similar arrhythmogenic ectopic discharge or premature atrial contractions (PACs) originating from the inferior vena cava (IVC) have been rarely described. We present the case of a 51-year-old man with paroxysmal AF undergoing electrophysiological study. Twelve-lead electrocardiography demonstrated PACs with negative P waves in the inferior leads. Ectopic beats originating from the ostium of the IVC, which were likely to initiate AF, were observed. Furthermore, the origin of the PAC was visualized using an electroanatomical local activation timing (LAT) map and located close to the fibrotic tissue of the vasculature. Radiofrequency catheter ablation was performed at the earliest activation site, and ectopic beats were not observed after the procedure. This is the first report to demonstrate a LAT contact map of ectopic discharge arising from the IVC. If PACs with negative P waves in the inferior leads are found in a patient with AF, the IVC should be investigated for possible focal ectopic discharges. Learning objective: Non-pulmonary vein foci play a significant role in the pathogenesis of atrial fibrillation (AF). However, inferior vena cava (IVC) triggers that initiate AF have rarely been described. Premature atrial contractions with negative P waves in the inferior leads may be associated with ectopic discharges originating from the IVC, which contribute to the initiation of AF.

The COVID-19 impacts and challenges to achieving sustainability in Japan's fisheries and aquaculture.

The Japanese fisheries, aquaculture, and seafood sectors have been undergoing continuous transformation affected by economic downturns due to the new coronavirus (COVID-19) pandemic. Analyses of the COVID-19 impacts on fishery, aquaculture and seafood sectors in six sites in different parts of Japan exhibit that the impacts of the economic recession due to the pandemic differ between sectors, species, and local communities. The impacts of the COVID-19 pandemic were multiplied by other national and international policy changes as well as other factors such as fish stock depletion and the possible relocation of fish stocks due to sea water temperature change. Stagnating demand for fisheries may give incentives to reinforce conservation and introduce new schemes aimed at seafood sustainability. There can be, however, a possible driver for a vicious cycle that induces overfishing and fish price deterioration. Stakeholder ingenuity and policy innovation are required to achieve sustainable fisheries.

Identification of cap-dependent endonuclease inhibitors with broad-spectrum activity against bunyaviruses.

Viral hemorrhagic fevers caused by members of the order Bunyavirales comprise endemic and emerging human infections that are significant public health concerns. Despite the disease severity, there are few therapeutic options available, and therefore effective antiviral drugs are urgently needed to reduce disease burdens. Bunyaviruses, like influenza viruses (IFVs), possess a cap-dependent endonuclease (CEN) that mediates the critical cap-snatching step of viral RNA transcription. We screened compounds from our CEN inhibitor (CENi) library and identified specific structural compounds that are 100 to 1,000 times more active in vitro than ribavirin against bunyaviruses, including Lassa virus, lymphocytic choriomeningitis virus (LCMV), and Junin virus. To investigate their inhibitory mechanism of action, drug-resistant viruses were selected in culture. Whole-genome sequencing revealed that amino acid substitutions in the CEN region of drug-resistant viruses were located in similar positions as those of the CEN α3-helix loop of IFVs derived under drug selection. Thus, our studies suggest that CENi compounds inhibit both bunyavirus and IFV replication in a mechanistically similar manner. Structural analysis revealed that the side chain of the carboxyl group at the seventh position of the main structure of the compound was essential for the high antiviral activity against bunyaviruses. In LCMV-infected mice, the compounds significantly decreased blood viral load, suppressed symptoms such as thrombocytopenia and hepatic dysfunction, and improved survival rates. These data suggest a potential broad-spectrum clinical utility of CENis for the treatment of both severe influenza and hemorrhagic diseases caused by bunyaviruses.