Evaluation of Pericardial Effusion in Dogs and Successful Treatment Using a Hemodialysis Fistula Needle: A Retrospective Study

FUS regulates RAN translation through modulating the G-quadruplex structure of GGGGCC repeat RNA in C9orf72-linked ALS/FTD

Abnormal expansions of GGGGCC repeat sequence in the noncoding region of the C9orf72 gene is the most common cause of familial amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). The expanded repeat sequence is translated into dipeptide repeat proteins (DPRs) by noncanonical repeat-associated non-AUG (RAN) translation. Since DPRs play central roles in the pathogenesis of C9-ALS/FTD, we here investigate the regulatory mechanisms of RAN translation, focusing on the effects of RNA-binding proteins (RBPs) targeting GGGGCC repeat RNAs. Using C9-ALS/FTD model flies, we demonstrated that the ALS/FTD-linked RBP FUS suppresses RAN translation and neurodegeneration in an RNA-binding activity-dependent manner. Moreover, we found that FUS directly binds to and modulates the G-quadruplex structure of GGGGCC repeat RNA as an RNA chaperone, resulting in the suppression of RAN translation in vitro. These results reveal a previously unrecognized regulatory mechanism of RAN translation by G-quadruplex-targeting RBPs, providing therapeutic insights for C9-ALS/FTD and other repeat expansion diseases.

Antisense, but not sense, repeat expanded RNAs activate PKR/eIF2α-dependent ISR in C9ORF72 FTD/ALS

GGGGCC (G4C2) hexanucleotide repeat expansion in the C9ORF72 gene is the most common genetic cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). The repeat is bidirectionally transcribed and confers gain of toxicity. However, the underlying toxic species is debated, and it is not clear whether antisense CCCCGG (C4G2) repeat expanded RNAs contribute to disease pathogenesis. Our study shows that C9ORF72 antisense C4G2 repeat expanded RNAs trigger the activation of the PKR/eIF2α-dependent integrated stress response independent of dipeptide repeat proteins that are produced through repeat-associated non-AUG-initiated translation, leading to global translation inhibition and stress granule formation. Reducing PKR levels with either siRNA or morpholinos mitigates integrated stress response and toxicity caused by the antisense C4G2 RNAs in cell lines, primary neurons, and zebrafish. Increased phosphorylation of PKR/eIF2α is also observed in the frontal cortex of C9ORF72 FTD/ALS patients. Finally, only antisense C4G2, but not sense G4C2, repeat expanded RNAs robustly activate the PKR/eIF2α pathway and induce aberrant stress granule formation. These results provide a mechanism by which antisense C4G2 repeat expanded RNAs elicit neuronal toxicity in FTD/ALS caused by C9ORF72 repeat expansions.

Retrospective evaluation of clinical signs, clinical course, and prognosis between dogs with left atrial rupture secondary to myxomatous mitral valve disease and those with neoplastic cardiac tamponade (2015-2019): 70 cases

OBJECTIVE

To describe the clinical signs, clinical course, and prognosis of suspected left atrial rupture (LAR) secondary to myxomatous mitral valve disease (MMVD) in dogs and to compare them with dogs with suspected neoplastic cardiac tamponade (NCT).

DESIGN

Retrospective study from November 2015 to October 2019 SETTING: An out-of-hours Emergency Animal Hospital.

ANIMALS

Twenty-three dogs with LAR secondary to MMVD (LAR group) and 47 dogs with NCT (NCT group).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The following were the characteristics of the study population (LAR group vs NCT groups) with P < 0.05 as the significance threshold: male sex, 83% vs 66%; median age, 11.9 vs 12.5 years; and median weight, 3.8 vs 6.4 kg (P < 0.001). Chihuahuas and Miniature Dachshunds were overrepresented in the LAR and NCT groups, respectively. Statistically different clinical findings between the 2 groups were as follows (LAR vs NCT): pulmonary edema, 43% vs 0%; pericardial thrombus, 70% vs 6% (P < 0.001); ineffectiveness of pericardiocentesis (whether aspiration of pericardial fluid was successful or not), 58% vs 2% (P < 0.001); mortality rate within 48 hours of visiting hospital, 35% vs 9% (P < 0.01). No significant difference was observed in survival time after discharge between the 2 groups.

CONCLUSIONS

The proportion of dogs with a diagnosis of LAR secondary to MMVD in dogs with cardiac tamponade was higher than the previously reported rate. Furthermore, the frequency of pulmonary edema, ineffectiveness of pericardiocentesis, and short-term mortality rate was higher in the LAR group than in the NCT group.

Case Report: Septic Pericarditis With Achromobacter xyloxidans in an Immunosuppressed Dog

A 5-year-old female spayed French Bulldog presented for anorexia and increased respiratory rate. On presentation, she was dyspneic with stridor and increased bronchovesicular sounds. Point-of-care ultrasound identified pericardial effusion. Thoracic radiographs identified pleural effusion, a wide cranial mediastinum, and multifocal unstructured interstitial pulmonary opacities. Bloodwork revealed a moderate leukocytosis characterized by a mature neutrophilia with a left shift, hypoalbuminemia, mildly increased alkaline phosphatase activity, and moderate hypokalemia. Thoracic CT findings revealed moderate pericardial and bilateral pleural effusion, mediastinal effusion, and moderate cranial mediastinal lymphadenopathy. Diagnostic thoracocentesis and pericardiocentesis revealed septic exudates with bacilli. Two days later, a median sternotomy and pericardiectomy were performed. Aerobic cultures of the effusions grew Achromobacter xylosoxidans ss deitrificans. The patient was treated with Amoxicillin-clavulanate and enrofloxacin for 12 weeks and clinically fully recovered. Achromobacter xylosoxidans has not been reported as a cause of purulent pericarditis and pyothorax in a dog. Uniquely, this patient is suspected of developing this infection secondary to immunosuppression.