Splatter generated by oral surgery irrigation and its implication for infection control.

OBJECTIVES: This study aimed to evaluate the splatter contamination generated by rotary instrumentation and irrigation during simulations of surgical extractions. Specifically, comparisons of the splatters generated were made between traditional assistant-based irrigation and self-irrigating drills and between saline and hydrogen peroxide irrigant. MATERIALS AND METHODS: A fluorescein solution was infiltrated into the irrigation system of high-speed drills, and the surgical extraction procedures were performed on manikins with the typodont teeth. Filter papers were placed at the predetermined locations around the operatory to absorb the fluorescein splatters; these samples underwent photographic image analysis. RESULTS: The patient chest showed the largest area of splatters, followed by the assistant's face shield. Procedures using the hydrogen peroxide irrigant generated a larger area of splatter than those using the saline irrigant. There was no difference between the splatters produced by assistant irrigation and self-irrigating drill procedures. CONCLUSIONS: Clinicians should observe and disinfect the locations contaminated by splatters to prevent the spread of infection, since using alternative irrigant or irrigation methods did not reduce the formation of splatters. CLINICAL RELEVANCE: Oral surgery drills with irrigation generate aerosols and splatters, which have potential to spread airborne pathogens. It is important to understand the patterns of splatters to mitigate contamination.

The effect of smartphone filming on student confidence in dental anesthesia techniques: A randomized trial.

OBJECTIVES: To examine the effect of individualized smartphone-recorded video review on dental student confidence in performing local anesthesia (LA) techniques, in a manikin-based simulation environment. METHODS: All University of Minnesota second-year dental students were invited to participate in this randomized trial developed following the Consolidated Standards of Reporting Trials statement, in 2020. With a parallel trial design, 104 students were randomly divided into two groups (52 per group) prior to the learning experience. Students and researchers were not blinded to group assignments. All students learned LA techniques in the same manikin-based simulation setting. The experimental group incorporated individualized smartphone filming into simulation training, and the control group did not. A paper-based questionnaire with 19 5-point Likert scale questions assessed the students' self-rated confidence levels in LA techniques before, immediately after, and approximately one month after the training. RESULTS: The final sample included 45 students in the experimental group (48.4%) and 48 in the control group (51.6%). In both groups, student confidence in performing LA techniques increased after completion of the training (p < 0.001), with no harm reported. The experimental group reported greater confidence in inferior alveolar nerve injection (p = 0.038), and in local anesthetic administration rate (p = 0.029), compared with the control group. CONCLUSIONS: This study suggested that the incorporation of smartphone-recorded video review in simulation training is beneficial for learning LA techniques. Further investigation on teaching methods to enhance student confidence and performance in LA administration is indicated.

The Applications and Challenges of the Development of In Vitro Tumor Microenvironment Chips.

The tumor microenvironment (TME) plays a critical, yet mechanistically elusive role in tumor development and progression, as well as drug resistance. To better understand the pathophysiology of the complex TME, a reductionist approach has been employed to create in vitro microfluidic models called "tumor chips". Herein, we review the fabrication processes, applications, and limitations of the tumor chips currently under development for use in cancer research. Tumor chips afford capabilities for real-time observation, precise control of microenvironment factors (e.g. stromal and cellular components), and application of physiologically relevant fluid shear stresses and perturbations. Applications for tumor chips include drug screening and toxicity testing, assessment of drug delivery modalities, and studies of transport and interactions of immune cells and circulating tumor cells with primary tumor sites. The utility of tumor chips is currently limited by the ability to recapitulate the nuances of tumor physiology, including extracellular matrix composition and stiffness, heterogeneity of cellular components, hypoxic gradients, and inclusion of blood cells and the coagulome in the blood microenvironment. Overcoming these challenges and improving the physiological relevance of in vitro tumor models could provide powerful testing platforms in cancer research and decrease the need for animal and clinical studies.

Identifying the core genome of the nucleus-forming bacteriophage family and characterization of Erwinia phage RAY.

We recently discovered that some bacteriophages establish a nucleus-like replication compartment (phage nucleus), but the core genes that define nucleus-based phage replication and their phylogenetic distribution were unknown. By studying phages that encode the major phage nucleus protein chimallin, including previously sequenced yet uncharacterized phages, we discovered that chimallin-encoding phages share a set of 72 highly conserved genes encoded within seven distinct gene blocks. Of these, 21 core genes are unique to this group, and all but one of these unique genes encode proteins of unknown function. We propose that phages with this core genome comprise a novel viral family we term Chimalliviridae. Fluorescence microscopy and cryo-electron tomography studies of Erwinia phage vB_EamM_RAY confirm that many of the key steps of nucleus-based replication encoded in the core genome are conserved among diverse chimalliviruses, and reveal that non-core components can confer intriguing variations on this replication mechanism. For instance, unlike previously studied nucleus-forming phages, RAY doesn't degrade the host genome, and its PhuZ homolog appears to form a five-stranded filament with a lumen. This work expands our understanding of phage nucleus and PhuZ spindle diversity and function, providing a roadmap for identifying key mechanisms underlying nucleus-based phage replication.

Identifying the core genome of the nucleus-forming bacteriophage family and characterization of Erwinia phage RAY.

We recently discovered that some bacteriophages establish a nucleus-like replication compartment (phage nucleus), but the core genes that define nucleus-based phage replication and their phylogenetic distribution were still to be determined. Here, we show that phages encoding the major phage nucleus protein chimallin share 72 conserved genes encoded within seven gene blocks. Of these, 21 core genes are unique to nucleus-forming phage, and all but one of these genes encode proteins of unknown function. We propose that these phages comprise a novel viral family we term Chimalliviridae. Fluorescence microscopy and cryoelectron tomography studies of Erwinia phage vB_EamM_RAY confirm that many of the key steps of nucleus-based replication are conserved among diverse chimalliviruses and reveal variations on this replication mechanism. This work expands our understanding of phage nucleus and PhuZ spindle diversity and function, providing a roadmap for identifying key mechanisms underlying nucleus-based phage replication.

An Inexpensive Cardiovascular Flow Simulator for Cardiac Catheterization Procedure Using a Pulmonary Artery Catheter.

Cardiac catheterization associated with central vein cannulation can involve potential thrombotic and infectious complications due to multiple cannulation trials or improper placement. To minimize the risks, medical simulators are used for training. Simulators are also employed to test medical devices such as catheters before performing animal tests because they are more cost-effective and still reveal necessary improvements. However, commercial simulators are expensive, simplified for their purpose, and provide limited access sites. Inexpensive and anatomical cardiovascular simulators with central venous access for cannulation are sparse. Here, we developed an anatomically and physiologically accurate cardiovascular flow simulator to help train medical professionals and test medical devices. Our simulator includes an anatomical right atrium/ventricle, femoral and radial access sites, and considers the variability of arm position. It simulates physiological pulsatile blood flow with a setting for constant flow from 3 to 6 L/min and mimics physiological temperature (37°C). We demonstrated simulation by inserting a catheter into the system at radial/femoral access sites, passing it through the vasculature, and advancing it into the heart. We expect that our simulator can be used as an educational tool for cardiac catheterization as well as a testing tool that will allow for design iteration before moving to animal trials.