Maladaptation after a virus host switch leads to increased activation of the pro-inflammatory NF-κB pathway.

Myxoma virus (MYXV) causes localized cutaneous fibromas in its natural hosts, tapeti and brush rabbits; however, in the European rabbit, MYXV causes the lethal disease myxomatosis. Currently, the molecular mechanisms underlying this increased virulence after cross-species transmission are poorly understood. In this study, we investigated the interaction between MYXV M156 and the host protein kinase R (PKR) to determine their crosstalk with the proinflammatory nuclear factor kappa B (NF-κB) pathway. Our results demonstrated that MYXV M156 inhibits brush rabbit PKR (bPKR) more strongly than European rabbit PKR (ePKR). This moderate ePKR inhibition could be improved by hyperactive M156 mutants. We hypothesized that the moderate inhibition of ePKR by M156 might incompletely suppress the signal transduction pathways modulated by PKR, such as the NF-κB pathway. Therefore, we analyzed NF-κB pathway activation with a luciferase-based promoter assay. The moderate inhibition of ePKR resulted in significantly higher NF-κB­dependent reporter activity than complete inhibition of bPKR. We also found a stronger induction of the NF-κB target genes TNFα and IL-6 in ePKR-expressing cells than in bPKR-expressing cells in response to M156 in both transfection and infections assays. Furthermore, a hyperactive M156 mutant did not cause ePKR-dependent NF-κB activation. These observations indicate that M156 is maladapted for ePKR inhibition, only incompletely blocking translation in these hosts, resulting in preferential depletion of short­half-life proteins, such as the NF-κB inhibitor IκBα. We speculate that this functional activation of NF-κB induced by the intermediate inhibition of ePKR by M156 may contribute to the increased virulence of MYXV in European rabbits.

Effect of Myxoma Virus Species Jump on Iberian Hare Populations.

The myxoma virus species jump from European rabbits (Oryctolagus cuniculus) to Iberian hares (Lepus granatensis) has raised concerns. We assess the decline suffered by Iberian hare populations on the Iberian Peninsula and discuss the association between the effect of myxomatosis and the average abundance index, which we estimated by using hunting bags.

High Levels of Extracellular Potassium Can Delay Myxoma Virus Replication by Preventing Release of Virions from the Endosomes.

Potassium (K+) is one of the most abundant cations in the human body. Under normal conditions, the vast majority of K+ is found within cells, and the extracellular [K+] is tightly regulated to within 3.0 to 5.0 mM. However, it has recently been shown that high levels of localized necrosis can increase the extracellular concentration of K+ to above 50 mM. This raises the possibility that elevated extracellular K+ might influence a variety of biological processes that occur within regions of necrotic tissue. For example, K+ has been shown to play a central role in the replication cycles of numerous viral families, and in cases of lytic infection, localized regions containing large numbers of necrotic cells can be formed. Here, we show that the replication of the model poxvirus myxoma virus (MYXV) is delayed by elevated levels of extracellular K+. These increased K+ concentrations alter the cellular endocytic pathway, leading to increased phagocytosis but a loss of endosomal/lysosomal segregation. This slows the release of myxoma virus particles from the endosomes, resulting in delays in genome synthesis and infectious particle formation as well as reduced viral spread. Additionally, mathematical modeling predicts that the extracellular K+ concentrations required to impact myxoma virus replication can be reached in viral lesions under a variety of conditions. Taken together, these data suggest that the extracellular [K+] plays a role in determining the outcomes of myxoma infection and that this effect could be physiologically relevant during pathogenic infection. IMPORTANCE Intracellular K+ homeostasis has been shown to play a major role in the replication of numerous viral families. However, the potential impact of altered extracellular K+ concentrations is less well understood. Our work demonstrates that increased concentrations of extracellular K+ can delay the replication cycle of the model poxvirus MYXV by inhibiting virion release from the endosomes. Additionally, mathematical modeling predicts that the levels of extracellular K+ required to impact MYXV replication can likely be reached during pathogenic infection. These results suggest that localized viral infection can alter K+ homeostasis and that these alterations might directly affect viral pathogenesis.

10× single-cell sequencing revealed cellular composition heterogeneity in cardiac myxoma with malignant glandular properties.

Cardiac myxoma is the most common primary cardiac tumor in adults. The histogenesis and cellular composition of myxoma are still unclear. This study aims to reveal the role of myxoma cell components and their gene expression in tumor development. We obtained single living cells by enzymatic digestion of tissues from 4 cases of surgically resected cardiac myxoma. Of course, there was 1 case of glandular myxoma and 3 cases of nonglandular myxoma. Then, 10× single-cell sequencing was performed. We identified 12 types and 11 types of cell populations in glandular myxoma and nonglandular myxoma, respectively. Heterogeneous epithelial cells are the main components of glandular myxoma. The similarities and differences in T cells in both glandular and nonglandular myxoma were analyzed by KEGG and GO. The most important finding was that there was active communication between T cells and epithelial cells. These results clarify the possible tissue occurrence and heterogeneity of cardiac myxoma and provide a theoretical basis and guidance for clinical diagnosis and treatment.

Multimodality Imaging of Cardiac Myxomas.

Cardiac myxomas are the most common benign cardiac neoplasms. Echocardiography is the first-line imaging modality used to analyze cardiac masses, allowing the detection of tumor location, size, and mobility. However, additional imaging techniques are required to confirm the diagnosis, evaluate tissue characteristics of the mass, and assess potential invasion of surrounding structures. Second-line imaging includes cardiac magnetic resonance imaging (MRI) and/or computed tomography (CT) depending on availability and the patient's characteristics and preferences. The advantages of CT include its wide availability and fast scanning, which allows good image quality even in patients who have difficulty cooperating. MRI has excellent soft-tissue resolution and is the gold standard technique for noninvasive tissue characterization. In some cases, evaluation of the tumor metabolism using 18F-fluorodeoxyglucose positron emission tomography with CT may be useful, mainly if the differential diagnosis includes primary or metastatic cardiac malignancies. A cardiac myxoma can be identified by its characteristic location within the atria, typically in the left atrium attached to the interatrial septum. The main differential diagnoses include physiological structures in the atria like crista terminalis in the right atrium and the coumadin ridge in the left atrium, intracardiac thrombi, as well as other benign and malignant cardiac tumors. In this review paper, we describe the characteristics of cardiac myxomas identified using multimodality imaging and provide tips on how to differentiate myxomas from other cardiac masses.

Comparative analysis of two novel complete genomes of myxoma virus vaccine strains.

Myxoma virus (MYXV) is a double-stranded DNA-containing virus of the family Poxviridae, genus Leporipoxvirus. MYXV is an important model virus for evolutionary and immunological research and a promising oncolytic. In this study, we sequenced and analyzed two complete genomes of MYXV virus vaccine strains B-82 and Rabbivac-B, which are widely used for vaccine production in Russia. Here, we first show that MYXV vaccine strains B-82 and Rabbivac-B share a common origin with the American recombinant MYXV MAV vaccine strain. In addition, our data suggest that the MYXV B-82 and Rabbivac-B strains contain a number of genes at the 5' and 3' ends that are identical to the virulent MYXV Lausanne strain. Several unique genetic signatures were identified in the M013L, M017L, M023, and M121R genes, helping to achieve high genetic resolution between vaccine strains. Overall, these findings highlight the evolutionary flexibility of certain genes in the MYXV genome and provide insights into the molecular epidemiology of the virus and subsequent vaccine development.

Atypical cellular neurothekeoma of the oral mucosa: A rare case report and literature review.

Cellular neurothekeoma (CN) is a benign dermal neoplasm that most often affects the head and neck region and rarely occurs in the oral mucosa. We report a rare case of CN with atypical features on the floor of the mouth and summarize the reported cases of oral CN in English-language literature. A 62-year-old woman presented with a 6-month history of a painless mass on the floor of the mouth. Histopathological analysis of the excised specimen revealed a proliferation of neoplastic cells with oval to spindle morphology arranged in a vaguely nested and multinodular architecture separated by scarce hyaline collagen within a predominantly myxoid-rich stroma. The tumor cells were positive for NSE, and CD63 (NKI/C3), and negative for S100 protein, CD34, and SMA. Thus, the final diagnosis was CN. In addition, we summarized all clinicopathological data on oral CNs reported in the English-language literature. Nineteen cases were reviewed. Among them, only one case affected the floor of the mouth of a young girl, in contrast to the present case that occurred in an elderly woman. CN is particularly rare in this location and may be a diagnostic challenge for oral pathologists due to its rarity and morphological similarity with other lesions.

Sarcomas of synovial origin in dogs: An updated review.

The purpose of this review is to clarify the terminology, possible cells of origin, and expected behavior of the most common synovial tumors in dogs. The synovial lining consists of 2 cell types, type A and type B. Type A synoviocytes are histiocytes of bone marrow origin that are immunoreactive with antibodies against typical markers of histiocyte origin, such as CD18, Iba-1, and CD204. Certain breeds and dogs with previous injury to a joint, especially cranial cruciate ligament rupture, are predisposed to synovial histiocytic sarcoma. Type B synoviocytes are mesenchymal cells that produce synovial fluid. There are no specific markers of type B synoviocytes, but based on their gross and microscopic appearance, synovial myxosarcomas (previously considered synovial myxomas) are presumed to be of type B synoviocyte origin. These can infiltrate into surrounding tissues, but are slow-growing and rarely metastasize, and then only to regional lymph nodes. Synovial histiocytic sarcomas and myxosarcomas can cause lysis in multiple bones surrounding the joint, but they have different prognoses and require histopathology and sometimes immunohistochemistry to diagnose them. Synovial sarcoma and synovial cell sarcoma are terms used in the human medical literature for a tumor that is not of synovial origin; these terms should not be used in veterinary medicine.

Myxoma with rich blood supply in the left atrium.

Cardiac myxoma is the most common primary benign cardiac tumors, mostly found in the left atrium. It was previously reported that the main component of myxoma was myxoid stroma riched in acid-mucopolysaccharide, the blood vessels in which were sparsely distributed, being characterized as hypovascular tumor by contrast echocardiography (CE) and computed tomography angiography (CTA). There are few reports of myxoma with rich blood supply and we report one in the left atrium.

Intramuscular myxoma: unusual observation of spontaneous tumor size shrinkage.

Soft tissue tumors, whether benign or malignant, may grow over time or remain stable, but they usually do not spontaneously decrease in size. However, there are exceptions, such as inflammatory conditions, desmoid tumors, or benign cysts. Intramuscular myxomas are benign soft tissue tumors that typically present as a solitary, slow-growing, painless mass. They are generally treated by surgical resection, after which recurrence is rare. Here, we present a brief series of three unusual cases of intramuscular myxomas that spontaneously decreased in size. They were located in the cervical region, the right lower extremity, and the paravertebral lumbar region. Imaging findings and percutaneous biopsies confirmed the diagnosis in all cases. Follow-up imaging showed a spontaneous reduction in lesion volume over time, far exceeding the amount of tissue sample removed during biopsy. This unusual observation of spontaneous shrinkage may call into question the subsequent therapeutic approach to these lesions.

Incidental finding of atrial myxoma following curative treatment for paediatric neuroblastoma.

Cardiac tumours are uncommon in the general population and even more so in the paediatric population. Here we present a case of an asymptomatic 7-year-old male with history of high-risk neuroblastoma who underwent 1-year post-treatment surveillance scan with an incidental finding of intracardiac lesion found to be an atrial myxoma.

Pulmonary embolism from right ventricular myxoma in a child with undiagnosed Carney complex.

Pediatric pulmonary embolism occurs in 8.6-57 per 100,000 hospitalised children. We report a novel case of bilateral pulmonary emboli in a child presenting with dyspnoea who was found to have large right ventricular myxoma and subsequent diagnosis of Carney complex. After resection of the right ventricular myxoma and bilateral pulmonary embolectomy, she had a full recovery and an excellent outcome.

Long-term control of haemorrhagic brain metastases from atrial myxoma after radiotherapy.

BACKGROUND: Cardiac myxoma is a rare, benign tumour that commonly originates in the left atrium and may lead to embolic events. Parenchymal brain metastases represent a rare neurological manifestation. While surgical intervention is commonly used, there is limited information on long-term outcomes after radiotherapy treatment. This report describes a case of successful treatment of haemorrhagic brain metastases with radiotherapy and offers a literature review of long-term results after radiotherapy treatment. CASE REPORT: A 49-year-old woman presented with multiple haemorrhagic brain lesions and a cardiac mass. Surgical removal of the cardiac mass and the symptomatic brain lesion confirmed metastatic cardiac myxoma. Post-surgery, she experienced fatigued and neurocognitive impairment and was closely monitored. However, the metastases progressed. She subsequently received whole-brain radiotherapy, resulting in complete response. Seven years later, she remains in remission, although with enduring neurocognitive impairment. CONCLUSIONS: Whole-brain radiotherapy can provide long-term control of haemorrhagic brain metastases arising from cardiac myxoma. Radiotherapy dose and treatment volume need careful consideration to reduce toxicity.

The Role of Methylation Analysis in Distinguishing Cellular Myxoma from Low-Grade Myxofibrosarcoma.

Cellular myxoma is a benign soft tissue tumor frequently associated with GNAS mutation that may morphologically resemble low-grade myxofibrosarcoma. This study aimed to identify the undescribed methylation profile of cellular myxoma and compare it to myxofibrosarcoma. We performed molecular analysis on twenty cellular myxomas and nine myxofibrosarcomas and analyzed the results using the methylation-based DKFZ sarcoma classifier. A total of 90% of the cellular myxomas had GNAS mutations (four loci had not been previously described). Copy number variations were found in all myxofibrosarcomas but in none of the cellular myxomas. In the classifier, none of the cellular myxomas reached the 0.9 threshold. Unsupervised t-SNE analysis demonstrated that cellular myxomas form their own clusters, distinct from myxofibrosarcomas. Our study shows the diagnostic potential and the limitations of molecular analysis in cases where morphology and immunohistochemistry are not sufficient to distinguish cellular myxoma from myxofibrosarcoma, particularly regarding GNAS wild-type tumors. The DKFZ sarcoma classifier only provided a valid prediction for one myxofibrosarcoma case; this limitation could be improved by training the tool with a more considerable number of cases. Additionally, the classifier should be introduced to a broader spectrum of mesenchymal neoplasms, including benign tumors like cellular myxoma, whose distinct methylation pattern we demonstrated.

Myxoma embolization during electroconvulsive therapy. An unusual presentation.

We describe a comatose female patient after electroconvulsive therapy. Head imaging showed diffuse cerebral emboli. Transesophageal echocardiography showed left atrial myxoma which was resected soon thereafter. The article describes the presentation, complications and treatment of myxomas and discusses electroconvulsive therapy, its adverse events and the possible relation to myxoma embolization.

Autocrine Regulation of Interleukin-6 via the Activation of STAT3 and Akt in Cardiac Myxoma Cells.

Plasma concentrations of a pleiotropic cytokine, interleukin (IL)-6, are increased in patients with cardiac myxoma. We investigated the regulation of IL-6 in cardiac myxoma. Immunohistochemical staining and reverse transcription-polymerase chain reaction (RT-PCR) revealed that IL-6 and its receptors, IL-6 receptor (IL-6R) and gp130, co-existed in the myxoma cells. Myxoma cells were cultured, and an antibody array assay showed that a conditioned medium derived from the cultured myxoma cells contained increased amounts of IL-6. Signal transducer and activator of transcription (STAT) 3 and Akt were constitutively phosphorylated in the myxoma cells. An enzyme-linked immunosorbent assay (ELISA) showed that the myxoma cells spontaneously secreted IL-6 into the culture medium. Real-time PCR revealed that stimulation with IL-6 + soluble IL-6R (sIL6R) significantly increased IL-6 mRNA in the myxoma cells. Pharmacological inhibitors of STAT3 and Akt inhibited the IL-6 + sIL-6R-induced gene expression of IL-6 and the spontaneous secretion of IL-6. In addition, IL-6 + sIL-6R-induced translocation of phosphorylated STAT3 to the nucleus was also blocked by STAT3 inhibitors. This study has demonstrated that IL-6 increases its own production via STAT3 and Akt pathways in cardiac myxoma cells. Autocrine regulation of IL-6 may play an important role in the pathophysiology of patients with cardiac myxoma.

Atypical presentation of left atrial myxoma: A case report.

Atrial Myxoma is the most common primary benign tumour of the heart, commonly found in the left atrium. It typically presents in young females with characteristic features such as, constitutional symptoms, chest pain, and cardiac murmurs. However, atypical presentations can occur; causing a diagnostic challenge. This case report describes a 75-year-old male who visited the cardiology outpatient department of Dow Institute of Cardiology, Karachi on 18th April, 2023 with a left-sided atrial myxoma in late adulthood without typical features including constitutional symptoms, chest pain, syncope, dizziness, digital clubbing or neurologic findings. Further discussed are the diagnostic techniques used to find the tumour and the treatment strategy. This case report highlights the need for cardiologists to consider Atrial Myxoma as a potential diagnosis, even in the absence of typical symptoms, in elderly male population.

Cardiac myxoma as a rare acute heart failure etiology in paediatrics: A case report.

Cardiac myxoma is extremely rare in children. However, if not treated immediately, it may cause varying symptoms until sudden death. A-9-years old male Javanese child was brought to the emergency department of Prof. Soekandar General Hospital, Mojokerto with progressive dyspnoea since one month which got worse in the left decubitus position. There was no significant past medical history. Physical examination revealed hypotension, mitral stenosis, tricuspid regurgitation, and pulmonary congestion. Transthoracic echocardiography revealed a round pedunculated 3x3.3 cm mass in the Left Atrium that swingingly moved to the Left Ventricle during diastole. This was diagnosed provisionally as Myxoma with a differential of thrombus. After stabilization, he was referred to a tertiary hospital for emergency excision. Histopathology confirmed the myxoma. There were no symptoms and activity limitations during the 6 months follow-up. To the best of our knowledge, this is the first paediatric cardiac myxoma with Acute Heart Failure symptoms reported in Indonesia. Echocardiography is imperative for diagnosing myxoma. Appropriate and timely management results in an excellent outcome.

Right Ventricular Myxoma with a Papillary Muscular Origin.

Cardiac myxomas in the right ventricle are a very rare condition. In this case report, we describe an exceptionally uncommon case involving a right ventricular cardiac myxoma, originating from a papillary muscle, extending to both the tricuspid valve and the right atrium. The valve was able to be repaired via artificial chorda implantation.

Renal Embolism Associated with the Atrial Myxoma: A Case Report and Literature Review.

Renal embolisms due to cardiac myxomas are extremely rare; the clinical course, treatment, and prognosis of this disease are not established. A 69-year-old Japanese woman who underwent a nephrectomy for renal cell carcinoma 3 years earlier was hospitalized with a right occipital lobe cerebral infarction. Her renal function suddenly worsened 3 days post-admission: her serum creatinine rose from 1.46 mg/dL to 6.57 mg/dL and then to 8.03 mg/dL the next day, and hemodialysis therapy was started. Abdominal computed tomography (CT) scans showed patchy non-contrasted low-density areas in the right kidney, and chest CT scans and transesophageal ultrasonography revealed a left atrial tumor. We diagnosed renal infarction due to a left atrial myxoma. Hemodialysis and anticoagulant therapy (heparin) were continued, followed by the cardiac myxoma's resection. The patient's renal function gradually improved post-surgery, and the hemodialysis was discontinued. Considering our patient and 19 other case reports of renal infarction associated with cardiac myxoma, the treatment for such a renal infarction and the outcomes differ depending on the embolus site. The poor outcome of abdominal aortic embolism requires a prompt embolectomy, whereas a branch renal artery embolism requires anticoagulation therapy to prevent thrombosis formation around the myxoma.