Genome instability is an increasingly well-appreciated aspect of tumorigenesis, and genome rearrangements, such as translocations, copy number changes, and aneuploidy, are seen in many cancers. The Kolodner Laboratory has developed a variety of assays to study the formation of Gross Chromosomal Rearrangements (GCRs) in the model organism Saccharomyces cerevisiae, and our goal based on this work is to leverage the power of yeast genetics to gain insights in to the mechanisms by which increased genome instability contributes to cancer in humans. In Chapter 1, we describe collaborative efforts that used a large-scale screen to identify all the genes and pathways that interact to suppress genome instability in budding yeast. This led to the identification of 183 genes that directly suppress the accumulation of GCRs, 65 of which have not been previously identified. Bioinformatic analysis of cancer genome databases found that the human homologs of these genes are mutated in 90% and 70% of ovarian and colorectal cancers, respectively. Among the 65 novel suppressors was CDC73, a member of the Paf1 Complex that functions in transcription elongation and whose human homolog is a tumor suppressor. In Chapter 2, we investigate the mechanisms by which this gene suppresses genome instability. We demonstrate loss of CDC73 synergizes with mutations in telomere maintenance genes, and we show that increased GCRs rates are due to defects in telomerase and the accumulation of recombinogenic RNA: DNA hybrids. In Chapter 3, we expand this analysis to the rest of the Paf1 Complex members and demonstrate there is not a direct correlation between loss of complex function and an increase in GCR rate. We also defined an approximately 100 residue region of Cdc73 that is necessary and sufficient for its function and determined this region is necessary for nuclear localization and binding to Paf1. These findings on the structure and function of Cdc73 provide insights into how the human homolog functions as a tumor suppressor

Background

Acute pericarditis is a diffuse inflammation of the pericardial sac with many well-defined etiologies. Acute pericarditis as a vaccine-related adverse event is a rare entity, and the association between pericarditis and the immunogenic response to Coronavirus disease 2019 (COVID-19) vaccines is still being fully characterized.

Case report

A previously healthy 18-year-old man presented with fever, pleuritic chest pain, and shortness of breath 3 weeks after receiving the first dose of a COVID-19 mRNA-based vaccine. The patient was found to have a large pericardial effusion with early tamponade physiology requiring pericardiocentesis. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: As COVID-19 vaccination becomes more prevalent globally, physicians should be aware of pericarditis as a rare but potentially serious adverse reaction. Although a direct causal link cannot be demonstrated, we present this case to increase awareness among emergency physicians of pericarditis as a rare, but potentially serious adverse event associated with COVID-19 vaccination.

Background

In-hospital cardiac arrest (IHCA) carries a high mortality and providing resuscitation to COVID-19 patients presents additional challenges for emergency physicians. Our objective was to describe outcomes of COVID-19 patients suffering IHCA at a rural hospital in Southern California.

Methods

Single-center retrospective observational study. A hospital registry of COVID-19 patients was queried for all patients who suffered IHCA and received cardiopulmonary resuscitation (CPR) between May 1st and July 31st, 2020. A manual chart review was performed to obtain patient demographics, oxygen requirement prior to cardiac arrest (CA), details of the resuscitation including presence of an emergency physician, and final disposition.

Results

Twenty-one patients were identified, most of whom were Hispanic, male, and aged 50-70. The most common medical comorbidities were diabetes and hypertension. Most patients suffered respiratory arrest, with an initial rhythm of pulseless electrical activity or asystole. Return of spontaneous circulation (ROSC) was achieved in 3/9 patients already receiving mechanical ventilation, but all 3 expired within the following 24 h. ROSC was achieved in 10/12 patients not already intubated, though most also expired within a few days. The only 2 patients who survived to discharge suffered respiratory arrest after their oxygen delivery device dislodged.

Conclusion

At a small rural hospital with limited resources and a predominantly Hispanic population, cardiac arrest in a COVID-19 patient portends an extremely poor prognosis. A better appreciation of these outcomes should help inform emergency providers and patients when discussing code status and attempts at resuscitation, particularly in resource limited settings.

Background: Testicular torsion is a surgical emergency that needs prompt diagnosis and treatment. Point-of-Care ultrasound (POCUS) can not only establish the diagnosis but also guide the Emergency Physician in evaluating the response to manual detorsion. Case Report: We describe the case of a 13-year-old male who presented with acute scrotal pain. We demonstrate how bedside ultrasound was used to make the diagnosis of testicular torsion, guide the technique for manual detorsion, and confirm adequate return of blood flow. Our case illustrates the ease with which POCUS can be used in real time to diagnose and treat organ-threatening pathology, but more importantly, it shows how real-time POCUS was used to detorse a testicle that was refractory to the standard detorsion technique. Conclusion: The acute scrotum is a time-sensitive presentation and if testicular torsion is present, the diagnosis should be made as soon as possible. Many Emergency Departments do not have 24-hour coverage of ultrasound technicians, which would delay the diagnosis and treatment. Moreover, when manual detorsion is attempted, it often does not work because the testicle may need more than the standard 180 degree medial to lateral rotation. POCUS provides real-time analysis of return of blood flow and can thus guide further rotation, or opposite direction rotation, as needed.

Objective

The treatment of outpatient COVID-19 patients at high risk of disease progression has been challenging, as both the virus and available therapeutics change. Here, we sought to evaluate the effect of vaccination status on the use of sotrovimab during the early phase of the Omicron surge.

Methods

This was a retrospective observational study performed at El Centro Regional Medical Center, a rural hospital on the southern Californian border. The electronic medical record was queried for all emergency department (ED) patients who received an infusion of sotrovimab between January 6 and February 6, 2022. We obtained patient demographics, COVID-19 vaccination status, medical comorbidities, and whether patients returned to the ED within 30 days. We stratified our cohort according to vaccination status and performed a multivariable logistic regression model to evaluate the relationship between these factors.

Results

One hundred seventy patients received an infusion of sotrovimab in the ED. The patient cohort had a median age of 65 years, 78.2% were Hispanic, and obesity (63.5%) was the most common comorbidity. A total of 73.5% of patients were vaccinated against COVID-19. A total of 12/125 (9.6%) of vaccinated patients returned to the ED within 30 days, versus 10/45 (22.2%) in the unvaccinated cohort, which was statically significant (P = 0.03). The presence of medical comorbidities was not associated with the primary outcome.

Conclusion

Of patients who received sotrovimab, those who were vaccinated were less likely to return to the ED within 30 days compared to those who were unvaccinated. Given the effectiveness of the COVID-19 vaccination campaign, and with the emergence of new variants, it is unclear what role monoclonal antibody therapy should play in the treatment of outpatient COVID-19 patients.

Pneumomediastinum is a rare complication of substance use, likely due to a Valsalva maneuver after drug inhalation. There are no previously documented associations between pneumomediastinum and opioid use. A 30-year-old man with a history of recent heroin and fentanyl inhalation presented to the emergency department in respiratory distress requiring intubation. His course was complicated by pneumomediastinum which subsequently developed tension physiology. He required emergent surgical decompression with a "blowhole incision" to his anterior chest. Although a rare complication of polysubstance use, pneumomediastinum can progress to tension physiology, requiring prompt diagnosis and management.

Defects in the genes encoding the Paf1 complex can cause increased genome instability. Loss of Paf1, Cdc73, and Ctr9, but not Rtf1 or Leo1, caused increased accumulation of gross chromosomal rearrangements (GCRs). Combining the cdc73Δ mutation with individual deletions of 43 other genes, including TEL1 and YKU80, which are involved in telomere maintenance, resulted in synergistic increases in GCR rates. Whole genome sequence analysis of GCRs indicated that there were reduced relative rates of GCRs mediated by de novo telomere additions and increased rates of translocations and inverted duplications in cdc73Δ single and double mutants. Analysis of telomere lengths and telomeric gene silencing in strains containing different combinations of cdc73Δ, tel1Δ and yku80Δ mutations suggested that combinations of these mutations caused increased defects in telomere maintenance. A deletion analysis of Cdc73 revealed that a central 105 amino acid region was necessary and sufficient for suppressing the defects observed in cdc73Δ strains; this region was required for the binding of Cdc73 to the Paf1 complex through Ctr9 and for nuclear localization of Cdc73. Taken together, these data suggest that the increased GCR rate of cdc73Δ single and double mutants is due to partial telomere dysfunction and that Ctr9 and Paf1 play a central role in the Paf1 complex potentially by scaffolding the Paf1 complex subunits or by mediating recruitment of the Paf1 complex to the different processes it functions in.

Gross chromosomal rearrangements (GCRs) play an important role in human diseases, including cancer. The identity of all Genome Instability Suppressing (GIS) genes is not currently known. Here multiple Saccharomyces cerevisiae GCR assays and query mutations were crossed into arrays of mutants to identify progeny with increased GCR rates. One hundred eighty two GIS genes were identified that suppressed GCR formation. Another 438 cooperatively acting GIS genes were identified that were not GIS genes, but suppressed the increased genome instability caused by individual query mutations. Analysis of TCGA data using the human genes predicted to act in GIS pathways revealed that a minimum of 93% of ovarian and 66% of colorectal cancer cases had defects affecting one or more predicted GIS gene. These defects included loss-of-function mutations, copy-number changes associated with reduced expression, and silencing. In contrast, acute myeloid leukaemia cases did not appear to have defects affecting the predicted GIS genes.