Logical Fallacies in Missed Diagnosis of Stridorous Patients: A Case Report.

Tracheal stenosis and paradoxical vocal fold motion are both common laryngological diagnoses that can present with similar symptoms of dyspnea. Co-morbid psychiatric issues can complicate diagnostic accuracy and lead to logical fallacies in the attribution of symptom etiology. We present a case of a 38-year-old female who presented repeatedly to the emergency department with respiratory distress, inspiratory stridor, wheezing, and anxiety. On examination, she had stridor that appeared to correlate with episodes of elevated anxiety and bedside laryngoscopy which showed intermittent paradoxical vocal fold motion. A computed tomography scan showed 40% narrowing of the distal tracheal lumen, but symptoms were felt to be inconsistent and out of proportion to stenosis. She was seen several more times in the ED and eventually followed up in the laryngology clinic, where she had a tracheoscopy showing Cotton Meyer grade III stenosis. This unique case highlights the logical fallacies that may lead to misdiagnosis when evaluating stridorous patients with comorbid personality and anxiety disorders.

Periprosthetic distal femur fractures treated by retrograde intramedullary nails with a 10-degree distal bend achieve significantly better post-operative radiographic alignment when compared to conventional retrograde nails.

INTRODUCTION: Periprosthetic distal femur fractures (PPDFFs) are a common complication after total knee arthroplasty (TKA). In the setting of well-fixed TKA components, treatment options include retrograde intramedullary nailing (rIMN) or lateral locked plating. Treatment with rIMN has historically been associated with potential for extension deformity when using conventional nails. We hypothesized that the PPDFFs treated with an intramedullary nail with a specifically designed 10-degree distal bend for periprosthetic fractures would result in improved post-operative sagittal alignment compared to conventional intramedullary nails. MATERIALS AND METHODS: The study was conducted at a level-1 trauma center over a 12-year period (2010 - 2022). Patients over the age of 18 who sustained a PPDFF treated with rIMN were identified. The primary outcomes of the study were post-operative coronal and sagittal alignment determined by reviewing post-operative radiographs. RESULTS: A total of 50 patients were included. Twenty-three patients were treated with a rIMN with a 10° distal bend. Twenty-seven patients were treated with a rIMN with distal bend of 5° The mean aPDFA for the 10° distal bend group was 81.7° compared to 92.8° in the 5° distal bend group (p<0.001). There were 3/23 (13%) significant sagittal plane deformities the 10° distal bend group compared to 11/27 (41%) in the 5° distal bend group (p = 0.03). There was one patient with a post-operative extension deformity in the 10° distal bend group compared to 11 patients in the 5° distal bend group (p = 0.02). CONCLUSION: Retrograde intramedullary nailing of PPDFF with a 10° distal bend results in significantly better alignment in the sagittal plane when compared to a conventional 5° nail. The use of a 5° nail resulted in an extension deformity significantly more frequently. We therefore recommend the utilization of a rIMN with a 10° distal bend when treating PPDFFs. SUMMARY: Periprosthetic distal femur fractures are a common complication following total knee arthroplasty. While several studies report on the use of retrograde intramedullary nails in the treatment of periprosthetic distal femur fractures, there are limited reports of the use of a novel retrograde intramedullary nail with a 10° distal bend in the treatment of these injuries. Herein we present a radiographic study comparing coronal and sagittal postoperative alignment following treatment with retrograde intramedullary nails with a 10° distal bend versus conventional retrograde nails with a 5° distal bend.

Treatment of Diaphyseal Tibial Fractures Distal to a Total Knee Arthroplasty by Intramedullary Nailing Is Safe and Effective.

OBJECTIVES: To report the clinical result of a series of patients who underwent intramedullary nailing (IMN) of tibial shaft fractures distal to a total knee arthroplasty (TKA). DESIGN: Retrospective case series. SETTING: Level-1 trauma center. PATIENTS/PARTICIPANTS: Patients who sustained a tibial shaft fracture distal to a TKA treated with an IMN. INTERVENTION: IMN of tibial shaft fractures distal to a TKA. MAIN OUTCOME MEASUREMENTS: Postoperative weight-bearing status, readmissions, and complications or failure of treatment within 90 days; Knee Injury and Osteoarthritis Outcome Scores at the final follow-up; failure of treatment; and revision surgery. RESULTS: Nine patients were included. The average age was 71.4 years (range 55-87 years). All TKAs were cemented. The average distance between the tibial keel and the cortical density of the tibial tubercle was 24.1 mm (range 19.5-26.7 mm). Six nails were inserted using an infrapatellar portal, 2 were inserted using a suprapatellar portal, and 1 was inserted using a lateral parapatellar approach. The median nail diameter was 10 mm (range 9-12 mm). All fractures were healed at the final follow-up. There were no infections or arthroplasty-related complications. Knee Injury and Osteoarthritis Outcome Scores ranged from 100% to 74% (median 82%). CONCLUSION: Overall, we report on the largest cohort in the literature undergoing IMN of a tibial shaft fracture distal to a TKA. We demonstrate that IMN of diaphyseal tibial fractures distal to a TKA can be performed safely. We additionally demonstrate that this treatment is highly effective in achieving fracture union with no arthroplasty-related complications. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Systematic analysis of F-box proteins reveals a new branch of the yeast mating pathway.

The mating pathway in yeast Saccharomyces cerevisiae has long been used to reveal new mechanisms of signal transduction. The pathway comprises a pheromone receptor, a heterotrimeric G protein, and intracellular effectors of morphogenesis and transcription. Polarized cell growth, in the direction of a potential mating partner, is accomplished by the G-protein ßγ subunits and the small G-protein Cdc42. Transcription induction, needed for cell-cell fusion, is mediated by Gßγ and the mitogen-activated protein kinase (MAPK) scaffold protein Ste5. A potential third pathway is initiated by the G-protein α subunit Gpa1. Gpa1 signaling was shown previously to involve the F-box adaptor protein Dia2 and an endosomal effector protein, the phosphatidylinositol 3-kinase Vps34. Vps34 is also required for proper vacuolar sorting and autophagy. Here, using a panel of reporter assays, we demonstrate that mating pheromone stimulates vacuolar targeting of a cytoplasmic reporter protein and that this process depends on Vps34. Through a systematic analysis of F-box deletion mutants, we show that Dia2 is required to sustain pheromone-induced vacuolar targeting. We also found that other F-box proteins selectively regulate morphogenesis (Ydr306, renamed Pfu1) and transcription (Ucc1). These findings point to the existence of a new and distinct branch of the pheromone-signaling pathway, one that likely leads to vacuolar engulfment of cytoplasmic proteins and recycling of cellular contents in preparation for mating.

The elemental sulfur-responsive protein (SipA) from the hyperthermophilic archaeon Pyrococcus furiosus is regulated by sulfide in an iron-dependent manner.

The gene (sipA) encoding the sulfur-induced protein A (PF2025) is highly upregulated during growth of Pyrococcus furiosus on elemental sulfur (S(0)). Expression of sipA is regulated by sulfide, the product of S(0) reduction, but in an iron-dependent manner. SipA is proposed to play a role in intracellular iron sulfide detoxification.