Upper back, neck, and shoulder pain during labor epidural analgesia: a quality improvement initiative.

BACKGROUND: Severe upper back/interscapular, neck and shoulder pain during labor epidural analgesia (PLEA) is not uncommon. The objective of this quality initiative was to evaluate the incidence, demographic associations and management of PLEA. METHODS: An eight-month, single-center quality improvement initiative was performed for the detection and management of PLEA. After survey-based consensus among obstetric anaesthetist attendings and fellows, a three-step PLEA treatment protocol with interventions and numeric rating scale (NRS, 0 - 10 scale) pain assessments was introduced. Demographic data and outcomes were compared among parturients with and without PLEA. RESULTS: Among 2888 women who received labor epidural analgesia from October 2022 through May 2023, 36 (1.2% [95% CI 0.9% to 1.7%]) reported PLEA. Women with PLEA were younger, more likely to be nulliparous, and had a higher body mass index (BMI) than women without PLEA (p < 0.05 for all). A total of 72.2% (26/36) of women with PLEA received at least one protocol treatment. Twenty-three women received first-line therapy, with pain relief in 91.3% (21/23). The median NRS score decreased from 9 [IQR 8-10] to 3 [1-4]. Women with PLEA had a higher incidence of cesarean delivery (CD) and a longer interval between epidural placement and delivery; 52.8 vs. 17.5% (p < 0.001) and 16.5 vs. 6.9 hours (p < 0.001), respectively. CONCLUSIONS: The incidence of PLEA was higher than previously reported. Patients with PLEA were younger, more commonly nulliparous, had higher BMI, longer epidural infusion times and higher CD rates. A three-step treatment protocol was successful in managing PLEA.

Ventriculo-gallbladder shunt: case series and literature review.

BACKGROUND: The ventriculoperitoneal shunt (VPS) is the gold-standard surgical technique to treat hypertensive hydrocephalus; however, it may fail in 20 to 70% of cases. The present study shows an alternative for patients with contraindications to VPS. METHODS: A case series of nine patients. The medical records of all patients under 17 years of age who underwent ventriculo-gallbladder (VGB) shunt at a pediatric hospital from January 2014 to October 2022 were reviewed. RESULTS: There were 6 (66.7%) males and 3 (33.3%) females. The average age of 73.6 months or 6.1 years at the time of surgery. They had undergone, on average, 5.1 VPS reviews before the VGB shunt. Five (55.5%) had complications of VGB shunt: infection (11.1%), atony (11.1%), hypodrainage (11.1%), and ventriculoenteric fistula (22.2%); all these patients got better at surgical reapproach, and in two of them, the VGB shunt was re-implanted. CONCLUSION: This case series shows a lower risk of death and a similar risk of complications compared to other alternative shunts. This article spotlighted VGB as a viable alternative when VPS fails or has contraindications.

Combination treatment with statins and bezafibrate induces myotoxicity via inhibition of geranylgeranyl pyrophosphate biosynthesis and Rho activation in L6 myoblasts and myotube cells.

Statins and fibrates are frequently used to treat hyperlipidemia; however, these drugs may have adverse effects such as rhabdomyolysis. The incidence of rhabdomyolysis due to fibrates and statins is low (0.0028-0.0096%) when administered as monotherapy, however it increases to 0.015-0.021% when the drugs are used in combination. The mechanism underlying myotoxicity induced by the combination of statins and fibrates is yet unclear. Here, we investigated the mechanisms underlying induced myotoxicity in rat myoblasts L6 and differentiated L6 cells (myotubes) using a combination of statins and fibrates. We found that cell death induced by a combination of fluvastatin or simvastatin with bezafibrate or fenofibrate in L6 myoblasts and myotubes was mediated by inhibition of geranylgeranyl pyrophosphate (GGPP) production. Additionally, the drug combination inhibited Rho activation in L6 myoblasts and myotube cells. In L6 myoblasts, the combination of statins and bezafibrate enhanced p27 expression and induced G1 arrest and apoptosis. Furthermore, combined treatment suppressed Akt activation and enhanced Bim expression in L6 myotubes but did not affect extracellular regulated protein kinase 1/2 activation. These results suggested that combined administration of statins and fibrates induced death of L6 myoblasts and myotube cells by inhibiting GGPP biosynthesis and Rho pathway activation. Supplementation with GGPP may be therapeutically beneficial for preventing myotoxicity associated with combined statin and fibrates treatment.

Tumor PD-L1 and VEGF Expression, and CD8 T Cell Infiltration Predict Clinical Response to Immune Checkpoint Inhibitors in Non-small Cell Lung Cancer.

BACKGROUND/AIM: We evaluated the efficacy of "the tumor immune microenvironment (TIME) classification" for predicting clinical response to immune checkpoint inhibitors (ICIs) in patients with non-small cell lung cancer (NSCLC). In addition, we aimed to evaluate the "modified TIME classification", which adds the vascular endothelial growth factor (VEGF) status to TIME. MATERIALS AND METHODS: Programmed cell death receptor ligand-1 (PD-L1), CD8 T cell tumor-infiltrating lymphocytes (CD8+TILs) count and VEGF expression analyses were performed using immuno - histochemistry in 44 patients who had undergone ICI monotherapy. RESULTS: Regarding TIME classification, type-I (PD-L1 high and CD8+TILs high) had a significantly higher response than the other types. Using the modified TIME classification, type-IA (PD-L1 high, CD8+TILs high, and VEGF low) had a significantly higher response than the other types. CONCLUSION: The modified TIME classification, which adds tumor VEGF expression to "the TIME classification", could be useful in predicting clinical response to ICI monotherapy.

S-1 and oxaliplatin versus tegafur-uracil and leucovorin as post-operative adjuvant chemotherapy in patients with high-risk stage III colon cancer: updated 5-year survival of the phase III ACTS-CC 02 trial.

BACKGROUND: The ACTS-CC 02 trial demonstrated that S-1 plus oxaliplatin (SOX) was not superior to tegafur-uracil and leucovorin (UFT/LV) in terms of disease-free survival (DFS) as adjuvant chemotherapy for high-risk stage III colon cancer (any T, N2, or positive nodes around the origin of the feeding arteries). We now report the final overall survival (OS) and subgroup analysis according to the pathological stage (TNM 7th edition) for treatment efficacy. PATIENTS AND METHODS: Patients who underwent curative resection for pathologically confirmed high-risk stage III colon cancer were randomly assigned to receive either UFT/LV (300 mg/m2 of UFT and 75 mg/day of LV on days 1-28, every 35 days, five cycles) or SOX (100 mg/m2 of oxaliplatin on day 1 and 80 mg/m2/day of S-1 on days 1-14, every 21 days, eight cycles). The primary endpoint was DFS and the patients' data were updated in February 2020. RESULTS: A total of 478 patients in the UFT/LV group and 477 patients in the SOX group were included in the final analysis. With a median follow-up time of 74.3 months, the 5-year DFS rate was 55.2% in the UFT/LV group and 58.1% in the SOX group [stratified hazard ratio (HR) 0.92; 95% confidence interval (CI) 0.76-1.11; P = 0.3973], and the 5-year OS rates were 78.3% and 79.1%, respectively (stratified HR 0.97; 95% CI 0.76-1.24; P = 0.8175). In the subgroup analysis, the 5-year OS rates in patients with T4N2b disease were 51.0% and 64.1% in the UFT/LV and SOX groups, respectively (HR 0.72; 95% CI 0.40-1.31). CONCLUSION: Our final analysis reconfirmed that SOX as adjuvant chemotherapy is not superior to UFT/LV in terms of DFS in patients with high-risk stage III colon cancer. The 5-year OS rate was similar in the UFT/LV and SOX groups.

Three-dimensional conformal radiation therapy for canine aortic body tumour: 6 cases (2014-2019).

OBJECTIVE: To determine the feasibility of three-dimensional conformal radiation therapy for canine aortic body tumours. MATERIALS AND METHODS: Medical records of dogs that had undergone three-dimensional conformal radiation therapy with presumptive diagnosis of aortic body tumour were reviewed for clinical characteristics, treatment modality and outcomes. RESULTS: Eight dogs were diagnosed with aortic body tumour and were treated with three-dimensional conformal radiation therapy. One dog had proliferation of a mass in the right atrium during treatment and died of respiratory distress. Another dog did not undergo follow-up CT to evaluate the treatment response due to the increased blood urea nitrogen values. The remaining 6 dogs were included in the case series. Radiotherapy was performed using a median dose per fraction of 7 Gy (3.3-7.14 Gy), a median of seven divided doses (7-15) and a total median dose of 49 Gy (45-50 Gy). The median number of CT scans during the follow-up period was 5 (range: 3-8 times). CT revealed acute side effects in four dogs-grade 1 effects related to the lung (n = 4) and skin (n = 2). Self-limiting or asymptomatic late side effects (grade 1 lung-related effect) were observed in three dogs. After therapy, one dog demonstrated a complete response, another demonstrated a partial response and the disease remained stable in four animals. The median follow-up period was 514.5 (235-1219) days. After three-dimensional conformal radiation therapy, the aortic body tumour reduced gradually over time without regrowth in all these 6 dogs. CLINICAL SIGNIFICANCE: In this small case series, aortic body tumours responded to three-dimensional conformal radiation therapy. Transient and self-limiting side effects of the treatments were common. Further controlled studies are required to prove the effectiveness and the safety of this intervention.

Immunological Response of Pigs to Human Cells, Including Issues Such as the Production of Natural Antibodies in Newborns.

Pigs have recently become very popular for use not only in xenotransplantation field, but in regeneration studies as well, sometimes with pigs being used as the scaffold. We have already presented our findings related to the pig immune system against human cells, including the complement systems, natural antibodies (NAs), and NK cells. In this study, we investigated the pig innate immunological reaction against human cells further. Our investigations included issues such as the production of NAs in newborns, day 0 and day 1, and sow colostrum. The alternative pathway for pig complement reacted with human cells, and pig NK cells and macrophages directly injured human aortic endothelial cells. Pig serum clearly contains the natural antibodies IgG and IgM to human peripheral blood mononuclear cells (PBMCs). Pig plasma from day 1 newborns contained almost the same levels of these natural antibodies to human PBMCs as those of sow plasma. On the other hand, pig plasma from day 0 newborns did not contain IgG and IgM to human PBMCs. In addition, sow colostrum clearly contained both IgG and IgM to human PBMCs. As expected, the pig innate immunity system reacted to human cells, including natural antibodies. However, the NAs of pigs, both IgM and IgG, against human cells do not exist in pig serum at day 0, but at day 1 and in mother's milk, indicating that NAs in newborns did not come from the placenta but from sow colostrum.

Impact of COX2 Inhibitor for Regulation of PD-L1 Expression in Non-small Cell Lung Cancer.

BACKGROUND/AIM: There is no clear evidence in the literature regarding the regulation of programmed cell death-ligand 1 (PD-L1) expression by cyclo-oxygenase-2 (COX2). In this study, whether PD-L1 expression was regulated by COX2 activity was examined in vitro. MATERIALS AND METHODS: Resected lung cancer specimens were analyzed for PD-L1 and COX2 expression by immunohistochemical analysis. Next, co-localization of PD-L1 and COX2 expression was analyzed by double-fluorescence staining. Lastly, the effect of COX2 inhibition on the expression of PD-L1 was examined using lung cancer cell lines. RESULTS: PD-L1 expression was significantly correlated with COX2 expression in the resected specimens. The majority of cancer cells that expressed PD-L1 also co-expressed COX2. However, treatment of lung cancer cell lines with a COX2 inhibitor had no impact on PD-L1 expression. CONCLUSION: Our results suggest that COX2 inhibition might have no effect on the usage of immune checkpoint inhibitors in lung cancer treatment.

WISP1/CCN4 aggravates cartilage degeneration in experimental osteoarthritis.

OBJECTIVE: Increased Wisp1 expression was previously reported in experimental and human osteoarthritis (OA). Moreover, adenoviral overexpression of Wisp1 in naïve mouse knee joints resulted in early OA-like cartilage lesions. Here, we determined how the matricellular protein WISP1 is involved in the pathology that occurs in the complex osteoarthritic environment with aging and experimental OA in wild type (WT) and Wisp1-/- mice. METHODS: WT and Wisp1-/- mice were aged or experimental OA was induced with intraarticular collagenase injection, destabilization of the medial meniscus (DMM) or anterior cruciate ligament transection (ACLT). Joint pathology was assessed using histology and microCT. Protease expression was evaluated with qRT-PCR and activity was determined by immunohistochemical staining of the aggrecan neoepitope NITEGE. Protease expression in human end-stage OA synovial tissue was determined with qRT-PCR after stimulation with WISP1. RESULTS: With aging, spontaneous cartilage degeneration in Wisp1-/- was not decreased compared to their WT controls. However, we observed significantly decreased cartilage degeneration in Wisp1-/- mice after induction of three independent experimental OA models. While the degree of osteophyte formation was comparable between WT and Wisp1-/- mice, increased cortical thickness and reduced trabecular spacing was observed in Wisp1-/- mice. In addition, we observed decreased MMP3/9 and ADAMTS4/5 expression in Wisp1-/- mice, which was accompanied by decreased levels of NITEGE. In line with this, stimulation of human OA synovium with WISP1 increased the expression of various proteases. CONCLUSIONS: WISP1 plays an aggravating role in the development of post-traumatic experimental OA.

The novel BMI-1 inhibitor PTC596 downregulates MCL-1 and induces p53-independent mitochondrial apoptosis in acute myeloid leukemia progenitor cells.

Disease recurrence is the major problem in the treatment of acute myeloid leukemia (AML). Relapse is driven by leukemia stem cells, a chemoresistant subpopulation capable of re-establishing disease. Patients with p53 mutant AML are at an extremely high risk of relapse. B-cell-specific Moloney murine leukemia virus integration site 1 (BMI-1) is required for the self-renewal and maintenance of AML stem cells. Here we studied the effects of a novel small molecule inhibitor of BMI-1, PTC596, in AML cells. Treatment with PTC596 reduced MCL-1 expression and triggered several molecular events consistent with induction of mitochondrial apoptosis: loss of mitochondrial membrane potential, BAX conformational change, caspase-3 cleavage and phosphatidylserine externalization. PTC596 induced apoptosis in a p53-independent manner. PTC596 induced apoptosis along with the reduction of MCL-1 and phosphorylated AKT in patient-derived CD34+CD38low/- stem/progenitor cells. Mouse xenograft models demonstrated in vivo anti-leukemia activity of PTC596, which inhibited leukemia cell growth in vivo while sparing normal hematopoietic cells. Our results indicate that PTC596 deserves further evaluation in clinical trials for refractory or relapsed AML patients, especially for those with unfavorable complex karyotype or therapy-related AML that are frequently associated with p53 mutations.

Expression of a Synthetic Gene of CTDM by Transgenic Animals.

BACKGROUND: The purpose of this study was to produce molecules that can precisely regulate the complement and coagulation system and to assess the expression of such molecules in transgenic animals. METHODS: The CTDM gene, which is composed of the delta-1-99 amino acid (aa) C1-INH, EGF domain 4-6 of thrombomoduline (TM), short consensus repeat (SCR) 2-4 of DAF(CD55), and SCR 2-4 of MCP(CD46) was established. The codon usage for expression in mammals was adopted. The cDNA of CTDM was subcloned into the pCPI site (the human insulin promoter and a cytomegalovirus enhancer). pCPI-CTDM was transfected into pig endothelial cells (PEC). The expression of the molecule was clearly assessed by means of flow cytometry. RESULTS: BD3F1 female mice were induced to superovulate and were then crossed with BD3F1 males. Micro-injection and embryo transfer were performed by standard methods, thus generating transgenic mice that express CTDM. The mice carried the CTDM plasmid, as verified by PCR. Tissue expression levels in transgenic mouse lines generated with the constructs were follows: pancreas, 1.0; brain, 5.4; thymus, 0.3; heart, 0.2; lung, 1.2; liver, 0.1; kidney, 0.1; intestine, 0.4; and spleen, 1.6. A naive control mouse was also analyzed in the exact manner as for the transgenic mice. CONCLUSIONS: A synthetic CTDM gene with codon usage optimized to the mammalian system represents a critical factor in the development of transgenic animals.

Studies of Pig Complement: Measurement of Pig CH50, ACH50, and Components.

BACKGROUND: On the basis of a comparison of the hemolytic complement titer in pigs with that in humans, the complement system of pigs was investigated. The response of innate immunity, such as the natural antibodies, against humans was also examined. METHODS: Hemolytic complement activity of pig serum was measured with the use of a microtitration technique. CH50 was determined according to the method of Mayer. ACH50 was assayed according to the methods of Platts-Milles and Ishizaka. Hemolytic activities of C1, C4, C2, C3, C5, C8, and C9 were estimated through the use of intermediate cells and reagents, as described previously. In addition, the pig natural anti-human antibody was studied with the use of human peripheral blood mononuclear cells (PBMCs). Human PBMCs were stained with 5% pig serum, followed by staining with fluorescein isothiocyanate-labeled goat anti-pig IgG and IgM. The resulting stained cells were quantified by use of a FACScalibur system. The alternative pathway of pig complement was also measured with the use of human erythrocytes and normal pooled pig serum with or without Mg(++)EGTA. RESULTS: Both the CH50 and ACH50 titers were lower than those of humans. Concerning the components, except for C3, each component, that is, C1, C4, C2, C5, C8, and C9, was also lower than that of humans, based on measured values for human complement components. Pig serum clearly contains natural antibodies, IgG and IgM, to human PBMCs. The alternative pathway of pig complement reacted with human erythrocytes. CONCLUSIONS: As a whole, pig innate immunity, the complement system and natural antibody, recognizes the surfaces of human cells.

HLA-G1, but Not HLA-G3, Suppresses Human Monocyte/Macrophage-mediated Swine Endothelial Cell Lysis.

The inhibitory function of HLA-G1, a class Ib molecule, on monocyte/macrophage-mediated cytotoxicity was examined. The expression of inhibitory receptors that interact with HLA-G, immunoglobulin-like transcript 2 (ILT2), ILT4, and KIR2DL4 (CD158d) on in vitro-generated macrophages obtained from peripheral blood mononuclear cells and the phorbol 12-myristate 13-acetate (PMA)-activated THP-1 cells were examined by flow cytometry. cDNAs of HLA-G1, HLA-G3, HLA-E, and human ß2-microglobulin were prepared, transfected into pig endothelial cells (PECs), and macrophage- and the THP-1 cell-mediated PEC cytolysis was then assessed. In vitro-generated macrophages expressed not only ILT2 and ILT4 but CD158d as well. The transgenic HLA-G1 on PEC indicated a significant suppression in macrophage-mediated cytotoxicity, which was equivalent to that of transgenic HLA-E. HLA-G1 was clearly expressed on the cell surface of PEC, whereas the levels of HLA-G3 were much lower and remained in the intracellular space. On the other hand, the PMA-activated THP-1 cell was less expressed these inhibitory molecules than in vitro-generated macrophages. Therefore, the HLA-G1 on PECs showed a significant but relatively smaller suppression to THP-1 cell-mediated cytotoxicity compared to in vitro-generated macrophages. These results indicate that by generating HLA-G1, but not HLA-G3, transgenic pigs can protect porcine grafts from monocyte/macrophage-mediated cytotoxicity.

Supplemental Analysis for N-linked Sugars in Adult Pig Islets.

The pig pancreas is considered to be one of the most suitable sources of islets for clinical xenotransplantation. However, after producing α1-3galactosyltransferase knockout pigs, most of the organs of these pigs showed less antigenicity to the human body. Wild-type adult pig islets (APIs) that originally produced negligible levels of α-Gal, different from neonatal porcine islet-like cell clusters, showed a clear antigenicity to human serum. Concerning the so-called non-Gal epitopes, many studies related to glycoproteins and glycolipids are ongoing in efforts to identify them. However, our knowledge of non-Gal glycoantigens remains incomplete. In our previous study, N-glycans were isolated from APIs, and the structures of 28 of the N-glycans were detected. In this study, to identify additional structures, further analyses were performed by liquid chromatography-mass spectrometry (LC-MS). N-glycans were isolated from APIs by the method described by O'Neil et al with minor modifications and LC-MS-based structural analyses were then performed. The detected N-glycan peaks in the LC-MS spectra were selected using the FLexAnalysis software program and the structures of the glycans were predicted using the GlyocoMod Tool. The API preparation contained 11 peaks and 16 structures were then nominated as containing N-linked sugars. Among them, 5 sulfated glycans were estimated, confirming the existence of sulfate structures in N-glycans in API. In addition, these data may supplement several N-glycan structures that contain two deoxyhexose units, such as fucose, to our previous report. The data herein will be helpful for future studies of antigenicity associated with API.

Knockout of Cytidine Monophospho-N-Acetylneuraminic Acid (CMP-NeuAc) Hydroxylase From Porcine Endothelial Cells by a CRISPR System.

BACKGROUND: We attempted to knock out the expression of Hanganutziu-Deicher (H-D) antigens through the use of a CRISPR (clustered regulatory interspaced short palindromic repeat)/Cas9 system for pig cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH). METHODS: Plasmids expressing hCas9 and sgRNA for pCMAH were prepared by ligating oligos into the BbsI site of pX330. The N-terminal and C-terminal EGFP coding regions overlapping 482 bp were PCR-amplified and placed under a ubiquitous CAG promoter. The approximately 400-bp genomic fragments containing the sgRNA target sequence of pCMAH were placed into the multi-cloning sites flanked by the EGFP fragments. The pCAG-EGxxFP-target was mixed with pX330 with/without the sgRNA sequences and then introduced into HEK293T cells. RESULTS: Four oligos and primers, gSO1, gSO3, gSO4, and gSO8, were nominated from 8 candidates. Among them, gSO1 showed the best efficiency. Pig endothelial cells (PECs) from an α-Gal knockout pig were then used to examine the changes in the expression of the H-D antigen by the knockout of the CMAH genome by the pX330-gS01. CONCLUSIONS: Changes in the expression of the H-D antigen in the PECs with the CRISPR (gS01) were clear in comparison with those in the parental cells, on the basis of FACS analysis data. The expression of the H-D antigen can be knocked out by use of the CRISPR system for pCMAH, thus confirming that this system is a very convenient system for producing knockout pigs.

Human HLA-Ev (147) Expression in Transgenic Animals.

BACKGROUND: In our previous study, we reported on the development of substituting S147C for HLA-E as a useful gene tool for xenotransplantation. In this study we exchanged the codon of HLA-Ev (147), checked its function, and established a line of transgenic mice. METHODS: A new construct, a codon exchanging human HLA-Ev (147) + IRES + human beta 2-microgloblin, was established. The construct was subcloned into pCXN2 (the chick beta-actin promoter and cytomegalovirus enhancer) vector. Natural killer cell- and macrophage-mediated cytotoxicities were performed using the established the pig endothelial cell (PEC) line with the new gene. Transgenic mice with it were next produced using a micro-injection method. RESULTS: The expression of the molecule on PECs was confirmed by the transfection of the plasmid. The established molecules on PECs functioned well in regulating natural killer cell-mediated cytotoxicity and macrophage-mediated cytotoxicity. We have also successfully generated several lines of transgenic mice with this plasmid. The expression of HLA-Ev (147) in each mouse organ was confirmed by assessing the mRNA. The chick beta-actin promoter and cytomegalovirus enhancer resulted in a relatively broad expression of the gene in each organ, and a strong expression in the cases of the heart and lung. CONCLUSION: A synthetic HLA-Ev (147) gene with a codon usage optimized to a mammalian system represents a critical factor in the development of transgenic animals for xenotransplantation.

Predicting future uncertainty constraints on global warming projections.

Projections of global mean temperature changes (ΔT) in the future are associated with intrinsic uncertainties. Much climate policy discourse has been guided by "current knowledge" of the ΔTs uncertainty, ignoring the likely future reductions of the uncertainty, because a mechanism for predicting these reductions is lacking. By using simulations of Global Climate Models from the Coupled Model Intercomparison Project Phase 5 ensemble as pseudo past and future observations, we estimate how fast and in what way the uncertainties of ΔT can decline when the current observation network of surface air temperature is maintained. At least in the world of pseudo observations under the Representative Concentration Pathways (RCPs), we can drastically reduce more than 50% of the ΔTs uncertainty in the 2040 s by 2029, and more than 60% of the ΔTs uncertainty in the 2090 s by 2049. Under the highest forcing scenario of RCPs, we can predict the true timing of passing the 2 °C (3 °C) warming threshold 20 (30) years in advance with errors less than 10 years. These results demonstrate potential for sequential decision-making strategies to take advantage of future progress in understanding of anthropogenic climate change.

Pinhal virus, a new arenavirus isolated from calomys tener in Brazil

Arenavirus Sabiá was originally isolated from a fatal human infection in Brazil, and after the occurrence of the second fatal human case in São Paulo state, epidemiologic and virologic studies were performed in the area where the patient lived, aiming at the identification of the Sabiá natural rodent reservoir. A broadly cross-reactive enzyme-linked immunosorbent assay (ELISA) was used to screen for antibody-positive samples. Antibodies to arenavirus were detected in two of the 55 samples of Calomys tener, and from these results, samples of rodents were analyzed by a broad RT-PCR assay. RT-PCR amplification detected arenavirus sequences in five of the 55 C. tener samples, and sequencing showed that this virus is a distinct form of Sabiá virus. Thus, we describe here the evidence for the circulation of a new arenavirus in Brazil (proposed name Pinhal virus) and its genetic characterization compared to other arenaviruses. This study also suggests C. tener as a probable rodent reservoir for this virus and associates this new virus with the lineage C of New World arenaviruses. Although we have defined some characteristics of this virus, so far, there is no evidence of its involvement in human disease.