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Integrin αIIbβ3, a transmembrane heterodimer, mediates platelet aggregation when it switches from an inactive to an active ligand-binding conformation following platelet stimulation. Central to regulating αIIbβ3 activity is the interaction between the αIIb and β3 extracellular stalks, which form a tight heterodimer in the inactive state and dissociate in the active state. Here, we demonstrate that alanine replacements of sensitive positions in the heterodimer stalk interface destabilize the inactive conformation sufficiently to cause constitutive αIIbβ3 activation. To determine the structural basis for this effect, we performed a structural bioinformatics analysis and found that perturbing intersubunit contacts with favorable interaction geometry through substitutions to alanine quantitatively accounted for the degree of constitutive αIIbβ3 activation. This mutational study directly assesses the relationship between favorable interaction geometry at mutation-sensitive positions and the functional activity of those mutants, giving rise to a simple model that highlights the importance of interaction geometry in contributing to the stability between protein-protein interactions.

The Salmonella Syst-OMICS consortium is sequencing 4,500 Salmonella genomes and building an analysis pipeline for the study of Salmonella genome evolution, antibiotic resistance and virulence genes. Metadata, including phenotypic as well as genomic data, for isolates of the collection are provided through the Salmonella Foodborne Syst-OMICS database (SalFoS), at https://salfos.ibis.ulaval.ca/. Here, we present our strategy and the analysis of the first 3,377 genomes. Our data will be used to draw potential links between strains found in fresh produce, humans, animals and the environment. The ultimate goals are to understand how Salmonella evolves over time, improve the accuracy of diagnostic methods, develop control methods in the field, and identify prognostic markers for evidence-based decisions in epidemiology and surveillance.

Objective Students in health profession education programs were severely affected by the COVID-19 pandemic at both didactic and clinical training levels. The purpose for this American Society for Clinical Pathology Board of Certification (ASCP BOC) study was to determine the impact of the COVID-19 pandemic on graduates. This study represents the perspectives of laboratory professional graduates who sat for the BOC certification in their respective professional disciplines. Methods A survey was sent to all graduates from the National Accrediting Agency for Clinical Laboratory Science (NAACLS), Accrediting Bureau of Health Education Schools (ABHES), and Commission on Accreditation of Allied Health Education Programs (CAAHEP) accredited programs who sat for the ASCP BOC examination in 2020 and 2021 to determine the impact of COVID-19 on laboratory professional graduates during the pandemic. Results A total of 180 graduates responded to the survey. The majority of graduates indicated that at least 1 didactic program component was shifted to an online system during the pandemic and that both clinical and nonclinical student laboratories were affected. Although program completion for most graduates was not delayed, one-third of graduates delayed taking their respective BOC exam. Due to the lack of knowledge application through practical hands-on laboratory experience in their educational programs, graduates reported feeling a lack of readiness with regards to preparing for the national certification examination as well as for employment. Conclusion The study results showed the pandemic greatly impacted the education experience and readiness for the ASCP BOC examinations for graduates. Factors such as the absence of in-person learning and hands-on experience—both crucial aspects in laboratory training—and the ripple effects as a result of the pandemic, such as job loss, financial constraints, and health concerns, contributed to the decreased quality of education for graduates. [ABSTRACT FROM AUTHOR]

αIIbβ3 activation in platelets is followed by activation of the tyrosine kinase c-Src associated with the carboxyl terminus of the β3 cytosolic tail. Exogenous peptides designed to interact with the αIIb transmembrane (TM) domain activate single αIIbβ3 molecules in platelets by binding to the αIIb TM domain and causing separation of the αIIbβ3 TM domain heterodimer. Here we asked whether directly activating single αIIbβ3 molecules in platelets using the designed peptide anti-αIIb TM also initiates αIIbβ3-mediated outside-in signaling by causing activation of β3-associated c-Src. Anti-αIIb TM caused activation of β3-associated c-Src and the kinase Syk, but not the kinase FAK, under conditions that precluded extracellular ligand binding to αIIbβ3. c-Src and Syk are activated by trans-autophosphorylation, suggesting that activation of individual αIIbβ3 molecules can initiate αIIbβ3 clustering in the absence of ligand binding. Consistent with this possibility, incubating platelets with anti-αIIb TM resulted in the redistribution of αIIbβ3 from a homogenous ring located at the periphery of discoid platelets into nodular densities consistent with clustered αIIbβ3. Thus, these studies indicate that not only is resting αIIbβ3 poised to undergo a conformational change that exposes its ligand-binding site, but it is poised to rapidly assemble into intracellular signal-generating complexes as well.

Objective Health professions education programs were severely affected by the COVID-19 pandemic at clinical and didactic training levels. The purpose for this American Society for Clinical Pathology–Board of Certification (BOC) study was to determine the impact of the COVID-19 pandemic on the graduates who sat for BOC certification in their respective professional disciplines from the perspective of program directors (PDs). A separate article will be published on the graduates' perspective. Methods A survey was sent to all PDs from the National Accrediting Agency for Clinical Laboratory Science, Accrediting Bureau of Health Education Schools, and Commission on Accreditation of Allied Health Education Programs, accredited programs whose graduates are certified by the BOC, to determine the impact of COVID-19 on healthcare graduates and education programs during the pandemic. Results A total of 201 PDs responded. All programs consistently reported that the pandemic had a negative impact on their students' BOC pass rate and scores. When asked what educational formats were used, all groups used virtual live lectures and recorded lectures. University programs were found to use more online student laboratories and simulation laboratory sessions than the hospital programs, affecting the psychomotor skills of their students. Conclusion The results indicated that the effects from the COVID-19 pandemic were related to the inherent differences between hospital and university programs. This study revealed that the pandemic affected university programs more than hospital programs. [ABSTRACT FROM AUTHOR]