Resident Perceptions of Simulcast Teaching: A Qualitative Study.

OBJECTIVES: During the COVID-19 pandemic, medical education programs were challenged to optimize learning while balancing social interaction with exposure risk. In response, our internal medicine (IM) residency program transitioned to "simulcast" educational sessions. In simulcast sessions, multiple small groups of learners met in person in separate rooms and connected to the large-group session via videoconferencing. This qualitative study describes IM residents' perceptions regarding the advantages and disadvantages of learning in simulcast compared to virtual and in-person settings during the pandemic. METHODS: Categorical IM residents at Penn State during the academic year 2020-2021 were invited to participate. Eligible residents participated in one 30-min virtual, semistructured focus group. We used inductive thematic coding to analyze resident responses. RESULTS: Forty-eight percent (n = 29/60) of invited residents participated in focus groups. In the simulcast setting, participants felt more accountability to participate in their small groups compared to a larger group or virtual setting. Educational experiences varied based upon facilitator skill level. Overall, in-person settings were preferred to virtual, when possible, due to increased social connection. Respondents identified educator enthusiasm and presentation quality as key to engagement regardless of setting. CONCLUSION: Residents had variable responses to the simulcast setting based upon their comfort with participation by group size, desire for social connection, and perception of teaching strategies. The key identified pitfalls to simulcast teaching were resident discomfort in small groups, heterogeneous learning experience, lack of engagement, and technology challenges. These pitfalls can be mitigated through strategic distribution of learners in groups, trained facilitators, and interactive teaching modalities. Given that simulcast and mixed (simulcast, virtual, and in-person) teaching settings are here to stay postpandemic, anticipating pitfalls and creating adaptable educational content that translates in multiple settings is crucial.

Experimentally Induced Pain Results in Reduced Activity of the Rotator Cuff Muscles in Healthy Subjects.

Shoulder pain is a complex, prevalent problem that is multifactorial in nature. While there are many potential causes, one common suspect is the rotator cuff musculature. The purpose of the present study was to induce pain in the supraspinatus muscle of healthy subjects and observe the resulting changes in muscle activity. Eight muscles on 23 subjects were assessed using electromyography: anterior, middle, and posterior deltoid; pectoralis major; upper trapezius; latissimus dorsi; serratus anterior; supraspinatus; and infraspinatus. It was hypothesized that the rotator cuff muscles would display reduced activity during pain, and that reductions in activity would remain after the pain had dissipated. Both of the rotator cuff muscles measured did indeed display reduced activity in a majority of the dynamic, isometric, and maximal contractions. Many of those reductions remained after the pain had subsided.

USPSTF recommends aspirin to prevent CVD in adults 40 to 59 y as an individual decision; not recommended for adults ≥60 y.

SOURCE CITATION: Davidson KW, Barry MJ, Mangione CM, et al. Aspirin use to prevent cardiovascular disease: US Preventive Services Task Force recommendation statement. JAMA. 2022;327:1577-84. 35471505.

Hv 1 Proton Channels in Dinoflagellates: Not Just for Bioluminescence?

Bioluminescence in dinoflagellates is controlled by HV 1 proton channels. Database searches of dinoflagellate transcriptomes and genomes yielded hits with sequence features diagnostic of all confirmed HV 1, and show that HV 1 is widely distributed in the dinoflagellate phylogeny including the basal species Oxyrrhis marina. Multiple sequence alignments followed by phylogenetic analysis revealed three major subfamilies of HV 1 that do not correlate with presence of theca, autotrophy, geographic location, or bioluminescence. These data suggest that most dinoflagellates express a HV 1 which has a function separate from bioluminescence. Sequence evidence also suggests that dinoflagellates can contain more than one HV 1 gene.

Spatial factors influence arithmetic performance: the case of the minus sign.

Spatial features of mathematical equations may influence how people solve and interpret those equations. This study examined whether manipulations of spatial features affected how participants solved and interpreted equations involving the minus sign. Undergraduate participants (N = 91) solved multioperation arithmetic equations involving addition, subtraction, and multiplication (e.g., 25 - 3 + 2 × 5 = __). We varied the spacing of the final three operands and the position of the first operator relative to the adjacent operands. Participants also generated a story problem to correspond with a given equation. We evaluated the procedures that participants used in solving the equations by analysing both their solutions and their written work. Both close spacing of the final three operands and position of the first operation sign influenced the procedures that participants used. Both of the spatial manipulations also influenced participants' interpretations of the conceptual structure of the equations, as revealed in the story problems that they generated. These results have implications for understanding how people process mathematical symbols and for mathematics education.

TILLING and ecotilling for rice.

Mutagenesis is frequently used to test gene function and to aid in crop improvement. Targeting Induced Local Lesions in Genomes (TILLING) is a reverse genetic strategy first developed to identify induced point mutations in Arabidopsis. This general strategy has since been applied to many plant and animal species. Here, we describe a protocol for high-throughput TILLING in rice. Gene segments are amplified using fluorescently tagged primers, and products are denatured and reannealed to form heteroduplexes between the mutated and wild-type sequences. These heteroduplexes are substrates for cleavage by single-strand-specific nucleases. Following cleavage, products are analyzed on denaturing polyacrylamide gels using the LI-COR DNA analyzer system. Several rice TILLING populations have been described, and a public mutation screening service is now available. The basic methods used for TILLING can be adapted for the discovery and cataloguing of natural nucleotide variation in populations, a strategy known as Ecotilling, which was first used to study genetic diversity among Arabidopsis ecotypes, and has since been applied to crop plants.

Fly-TILL: reverse genetics using a living point mutation resource.

Mutagenesis with ethylmethanesulfonate (EMS) has been the standard for traditional genetic screens, and in recent years has been applied to reverse genetics. However, reverse-genetic strategies require maintaining a viable germline library so that mutations that are discovered can subsequently be recovered. In applying our TILLING (Targeting Induced Local Lesions IN Genomes) method to establish a Drosophila reverse-genetic service (Fly-TILL), we chose to screen the Zuker lines, a large collection of EMS-mutagenized second- and third-chromosome balanced lines that had been established for forward-genetic screening. For the past four years, our Fly-TILL service has screened this collection to provide approximately 150 allelic series of point mutations for the fly community. Our analysis of >2000 point mutations and indels have provided a glimpse into the population dynamics of this valuable genetic resource. We found evidence for selection and differential recovery of mutations, depending on distance from balancer breakpoints. Although this process led to variable mutational densities, we have nevertheless been able to deliver potentially valuable mutations in genes selected by Fly-TILL users. We anticipate that our findings will help guide the future implementation of point-mutation resources for the Drosophila community.

Retention of induced mutations in a Drosophila reverse-genetic resource.

Targeting induced local lesions in genomes (TILLING) is a reverse-genetic method for identifying point mutations in chemically mutagenized populations. For functional genomics, it is ideal to have a stable collection of heavily mutagenized lines that can be screened over an extended period of time. However, long-term storage is impractical for Drosophila, so mutant strains must be maintained by continual propagation of live cultures. Here we evaluate a strategy in which ethylmethane sulfonate (EMS) mutagenized chromosomes were maintained as heterozygotes with balancer chromosomes for >100 generations before screening. The strategy yielded a spectrum of point mutations similar to those found in previous studies of EMS-induced mutations, as well as 2.4% indels (insertions and deletions). Our analysis of 1887 point mutations in 148 targets showed evidence for selection against deleterious lesions and differential retention of lesions among targets on the basis of their position relative to balancer breakpoints, leading to a broad distribution of mutational densities. Despite selection and differential retention, the success of a user-funded service based on screening a large collection several years after mutagenesis indicates sufficient stability for use as a long-term reverse-genetic resource. Our study has implications for the use of balancer chromosomes to maintain mutant lines and provides the first large-scale quantitative assessment of the limitations of using breeding populations for repositories of genetic variability.

TILLING to detect induced mutations in soybean.

BACKGROUND: Soybean (Glycine max L. Merr.) is an important nitrogen-fixing crop that provides much of the world's protein and oil. However, the available tools for investigation of soybean gene function are limited. Nevertheless, chemical mutagenesis can be applied to soybean followed by screening for mutations in a target of interest using a strategy known as Targeting Induced Local Lesions IN Genomes (TILLING). We have applied TILLING to four mutagenized soybean populations, three of which were treated with ethyl methanesulfonate (EMS) and one with N-nitroso-N-methylurea (NMU). RESULTS: We screened seven targets in each population and discovered a total of 116 induced mutations. The NMU-treated population and one EMS mutagenized population had similar mutation density (approximately 1/140 kb), while another EMS population had a mutation density of approximately 1/250 kb. The remaining population had a mutation density of approximately 1/550 kb. Because of soybean's polyploid history, PCR amplification of multiple targets could impede mutation discovery. Indeed, one set of primers tested in this study amplified more than a single target and produced low quality data. To address this problem, we removed an extraneous target by pretreating genomic DNA with a restriction enzyme. Digestion of the template eliminated amplification of the extraneous target and allowed the identification of four additional mutant alleles compared to untreated template. CONCLUSION: The development of four independent populations with considerable mutation density, together with an additional method for screening closely related targets, indicates that soybean is a suitable organism for high-throughput mutation discovery even with its extensively duplicated genome.

Adaptive evolution of the histone fold domain in centromeric histones.

Centromeric DNA, being highly repetitive, has been refractory to molecular analysis. However, centromeric structural proteins are encoded by single-copy genes, and these can be analyzed by using standard phylogenetic tools. The centromere-specific histone, CenH3, replaces histone H3 in centromeric nucleosomes, and is required for the proper distribution of chromosomes during cell division. Whereas histone H3s are nearly identical between species, CenH3s are divergent, with an N-terminal tail that is highly variable in length and sequence. Both the N-terminal tail and histone fold domain (HFD) are subject to adaptive evolution in Drosophila. Similarly, comparisons between Arabidopsis thaliana and Arabidopsis arenosa detected adaptive evolution, but only in the N-terminal tail. We have extended our evolutionary analyses of CenH3s to other members of the Brassicaceae, which allowed the detection of positive selection in both the N-terminal tail and in the HFD. We find that adaptively evolving sites in the HFD can potentially interact with DNA, including sites in the loop 1 region of the HFD that are required for centromeric targeting in Drosophila. Other adaptively evolving sites in the HFD can be localized on the structure of the nucleosome core particle, revealing an extended surface in addition to loop 1 in which conformational changes might alter histone-DNA contacts or water bridges. The identification of adaptively evolving sites provides a structural basis for the interaction between centromeric DNA and the protein that is thought to underlie the evolution of centromeres and the accumulation of pericentric heterochromatin.