Thoracic Aortic Graft Salvage after Sternal Wound Infection with Antibiotic Beads and Flap Coverage.

Infections involving thoracic aortic grafts are difficult to treat and have devastating consequences. The traditional approaches to surgical management include aggressive debridement with graft explantation and replacement. Despite treatment, the reported morbidity and mortality rates are high. The purpose of this study was to present our experience with an innovative approach to aortic graft salvage in the setting of sternal wound infection using antibiotic impregnated polymethylmethacrylate beads followed by definitive wound closure with flap coverage. A retrospective review identified patients with surgical wounds after aortic graft or cardiac valve placement over a 7-year period at a single institution. Patients were treated using an algorithm consisting of repeated surgical debridement and placement of antibiotic beads followed by flap coverage after suppression of the infection. A total of 20 patients were treated for surgical wounds, including 19 sternal and one thoracotomy wound. Culture positive surgical site infections were documented in 16 patients. One patient required a bead exchange before definitive closure. There were no in-hospital mortalities. All but two patients achieved successful infection suppression and wound closure with flap coverage. The use of antibiotic beads with serial debridement and flap closure may offer a valid option for aortic graft salvage in the setting of infected sternal wounds in the appropriate patient population. The proposed algorithm showed that patients may be successfully treated, and their infection suppressed without the need for graft removal. Mortality rates were lower from those previously reported in the literature.

A comparison of four commercially available RNA extraction kits for wastewater surveillance of SARS-CoV-2 in a college population.

Localized wastewater surveillance has allowed for public health officials to gain a broader understanding of SARS-CoV-2 viral prevalence in the community allowing public health officials time to prepare for impending outbreaks. Given variable levels of virus in the population through public health interventions, proper concentration and extraction of viral RNA is a key step in ensuring accurate detections. With many commercial RNA extraction kits and methodologies available, the performance of 4 different kits were evaluated for SARS-CoV-2 RNA detection in wastewater, specifically focusing on their applicability to lower population densities such as those at university campus dorms. Raw wastewater samples were collected at 4 sites on a college campus over a 24 hour period as a composite sample. Included in these sites was an isolation site that housed students that tested positive for Covid-19 via nasopharyngeal swabs. These samples were analyzed using the following kits: Qiagen All Prep PowerViral DNA/RNA kit, New England BioLabs Monarch RNA MiniPrep Kit, and Zymo Quick RNA-Viral Kit, and the Zymo Quick-RNA Fecal/Soil Microbe MicroPrep Kit. All four sites were processed according to the manufacturer's guidelines. Extractions were then quantified with RT-qPCR one-step reactions using an N2 primer and a linearized plasmid standard. While the Zymo Quick-RNA Fecal/Soil Microbe MicroPrep Kit (also known as the Zymo Environ Water RNA Kit) only recovered approximately 73% (±38%) SARS-CoV-2 RNA compared to the Zymo Quick-RNA Viral kit, it was the most time efficient kit to yield comparable results. This extraction kit had a cumulative processing time of approximately 5 h compared, while the other three kits had processing times between approximately 9 and 9.5 h. Based on the current research, the most effective kits for smaller population densities are pellet based and include a homogenization, inhibitor removal, and RNA preservation step.

Original research in the classroom: why do zebrafish spawn in the morning?

As part of an upper level undergraduate developmental biology course at the University of Minnesota Duluth, we developed a unit in which students carried out original research as part of a cooperative class project. Students had the opportunity to gain experience in the scientific method from experimental design all of the way through to the preparation of publication on their research that included text, figures, and tables. This kind of inquiry-based learning has been shown to have many benefits for students, including increased long-term learning and a better understanding of the process of scientific discovery. In our project, students designed experiments to explore why zebrafish typically spawn in the first few hours after the lights come on in the morning. The results of our experiments suggest that spawning still occurs when the dark-to-light transition is altered or absent. This is consistent with the work of others that demonstrates that rhythmic spawning behavior is regulated by an endogenous circadian clock. Our successes and failures carrying out original research as part of an undergraduate course should contribute to the growing approaches for using zebrafish to bring the excitement of experimental science to the classroom.