Pneumococcal Neuraminidases Increase Platelet Killing by Pneumolysin.

BACKGROUND: Platelets prevent extravasation of capillary fluids into the pulmonary interstitial tissue by sealing gaps in inflamed endothelium. This reduces respiratory distress associated with pneumonia. Streptococcus pneumoniae is the leading cause of severe community-acquired pneumonia. Pneumococci produce pneumolysin (PLY), which forms pores in membranes of eukaryotic cells including platelets. Additionally, pneumococci express neuraminidases, which cleave sialic acid residues from eukaryotic glycoproteins. In this study, we investigated the effect of desialylation on PLY binding and pore formation on platelets. MATERIALS AND METHODS: We incubated human platelets with purified neuraminidases and PLY, or nonencapsulated S. pneumoniae D39/TIGR4 and isogenic mutants deficient in PLY and/or NanA. We assessed platelet desialylation, PLY binding, and pore formation by flow cytometry. We also analyzed the inhibitory potential of therapeutic immunoglobulin G preparations (IVIG [intravenous immunoglobulin]). RESULTS: Wild-type pneumococci cause desialylation of platelet glycoproteins by neuraminidases, which is reduced by 90 to 100% in NanA-deficient mutants. NanC, cleaving only α2,3-linked sialic acid, induced platelet desialylation. PLY binding to platelets then x2doubled (p = 0.0166) and pore formation tripled (p = 0.0373). A neuraminidase cleaving α2,3-, α2,6-, and α2,8-linked sialic acid like NanA was even more efficient. Addition of polyvalent IVIG (5 mg/mL) decreased platelet desialylation induced by NanC up to 90% (p = 0.263) and reduced pore formation >95% (p < 0.0001) when incubated with pneumococci. CONCLUSION: Neuraminidases are key virulence factors of pneumococci and desialylate platelet glycoproteins, thereby unmasking PLY-binding sites. This enhances binding of PLY and pore formation showing that pneumococcal neuraminidases and PLY act in concert to kill platelets. However, human polyvalent immunoglobulin G preparations are promising agents for therapeutic intervention during severe pneumococcal pneumonia.

Perspectives of US Youths on Participation of Transgender Individuals in Competitive Sports: A Qualitative Study.

Importance: Rights and access for transgender individuals, including the participation of transgender athletes in sports, have long been debated. These discussions often center around fairness and mental health impacts on youths associated with identity-based inclusion in sports. Objective: To assess the experiences and perspectives of adolescents and young adults on the inclusion of transgender individuals in competitive sports. Design, Setting, and Participants: In this qualitative study, 5 open-ended survey questions were sent to the MyVoice cohort from December 10 to 17, 2021. MyVoice is a nationwide text-message polling platform of US youths aged 14 to 24 years. All coding and subsequent analysis was completed between January 10 and December 11, 2022. Main Outcomes and Measures: Qualitative perspectives of youths regarding transgender athlete participation in sports as measured by survey responses. Responses were reviewed using an inductive approach to qualitative thematic analysis to develop a codebook. The codes were independently applied to all responses by 2 investigators; discrepancies were resolved with discussion. Summary statistics were calculated for demographic characteristics and code frequencies, and χ2 tests (α = .05, 2-tailed) were used to evaluate differences in opinion based on gender identity and participation in competitive sports. Results: A total of 905 of 1199 youths (75%) responded to the survey. Respondents had a mean (SD) age of 20 (2) years; 482 (53%) identified as male, 29 (3%) identified as transgender, and 306 (34%) reported having participated in high school and/or collegiate athletics. Three themes emerged: (1) youths differed regarding the inclusion of transgender athletes based on gender identity vs sex assigned at birth, (2) many youths did not have personal experience related to the inclusion of transgender athletes, and (3) youths were uncertain about the impacts of gender identity-based participation on cisgender individuals but perceived positive impacts for transgender individuals. Nearly half of respondents (327 of 691 [47%]) thought that transgender athletes should participate based on their gender identity or personal preference, whereas 240 (35%) favored participation based on sex assigned at birth or in a transgender-only category. Respondents mentioned concern about the fairness of identity-based participation, specifically for cisgender women, but many (410 of 697 [59%]) also reported that it would be affirming for transgender athletes to participate based on gender identity. Conclusions and Relevance: The youths in our study differed in their opinions regarding sports participation of transgender youths, but many felt that inclusive policies would affirm and support the mental health of transgender individuals. Negative impacts on fairness were noted by some respondents. These findings suggest that nuanced policies are needed to address the participation of transgender athletes in competitive sports and should consider the impacts on and perspectives of youths most affected.

The Role of Medical Student Government in Responding to COVID-19.

The COVID-19 outbreak has sown clinical and administrative chaos at academic health centers throughout the country. As COVID-19-related burdens on the health care system and medical schools piled up, questions from medical students far outweighed the capacity of medical school administrators to respond in an adequate or timely manner, leaving students feeling confused and without clear guidance. In this article, incoming and outgoing executive leaders of the University of Michigan Medical School Student Council and medical school deans outline the specific ways they were able to bridge the gap between medical students and administrators in a time of crisis. To illustrate the value of student government during uncertain times, the authors identify the most pressing problems faced by students at each phase of the curriculum-preclerkship, clerkship, and postclerkship-and explain how Student Council leadership partnered with administrators to find creative solutions to these problems and provide guidance to learners. They end by reflecting on the role of student government more broadly, identifying 3 guiding principles of student leadership and how these principles enable effective student representation.

The Sinus Membrane-Maxillary Lateral Wall Complex: Histologic Description and Clinical Implications for Maxillary Sinus Floor Elevation.

Maxillary sinus floor elevation has been documented as a safe and predictable procedure for gaining vertical bone height in the atrophic posterior maxillae. Conversely, there is a lack of basic research on the characteristics of the union between the sinus membrane (SM) and the bone. Clinical implications of an impaired union in healthy or pathologic membranes remain unknown. The objective of this study was to present a comprehensive histologic and morphologic description of the sinus membrane-lateral bone wall complex. In 14 fresh cadaver heads, 28 lateral wall sinus augmentation procedures were performed to obtain SM samples. Samples were assessed using hematoxylin-eosin, Masson trichrome, and toluidine blue staining and immunofluorescence and immunohistochemistry procedures. Specimens were coded and studied by a trained examiner using an optical microscope at ×4, ×10, ×40, and ×100 objectives. Thickness and inflammation status were assessed in these samples. Overall SM thickness of the samples was 0.40 ± 0.12 mm and was positively correlated to the inflammatory condition of the membranes. Such low values are the consequence of limited inflammation. Most of the fibers and cells in the deeper layers of the SM ran in a horizontal direction, oriented parallel to the underlying bone wall. In the immunohistochemistry study, 3 out of 7 samples showed a certain degree of nestin expression, suggesting osteogenic potential in spite of the elderly specimens. Large variations in thickness across the SM were found. These were noted to be partially correlated to the SM inflammatory status. The vast majority of the fibers were oriented parallel to the maxillary lateral wall, and only a few isolated areas showed a stronger perpendicular attachment. This might indicate the surpassing importance of the SM inflammatory status, operator skill, and other anatomical factors over the sinus membrane-maxillary lateral wall complex interface. Moreover, about half of the SM investigated were positive for nestin, indicating their osteogenic potential.

Multigrowth Factor Delivery via Immobilization of Gene Therapy Vectors.

Molecules can be immobilized onto biomaterials by a chemical vapor deposition (CVD) coating strategy. Pentafluorophenolester groups react with amine side chains on antibodies, which can selectively immobilize adenoviral vectors for gene delivery of growth factors. These vectors can produce functional proteins within defined regions of biomaterials to produce customizable structures for targeted tissue regeneration.

Integration of 3D Printed and Micropatterned Polycaprolactone Scaffolds for Guidance of Oriented Collagenous Tissue Formation In Vivo.

Scaffold design incorporating multiscale cues for clinically relevant, aligned tissue regeneration has potential to improve structural and functional integrity of multitissue interfaces. The objective of this preclinical study is to develop poly(ε-caprolactone) (PCL) scaffolds with mesoscale and microscale architectural cues specific to human ligament progenitor cells and assess their ability to form aligned bone-ligament-cementum complexes in vivo. PCL scaffolds are designed to integrate a 3D printed bone region with a micropatterned PCL thin film consisting of grooved pillars. The patterned film region is seeded with human ligament cells, fibroblasts transduced with bone morphogenetic protein-7 genes seeded within the bone region, and a tooth dentin segment positioned on the ligament region prior to subcutaneous implantation into a murine model. Results indicate increased tissue alignment in vivo using micropatterned PCL films, compared to random-porous PCL. At week 6, 30 µm groove depth significantly enhances oriented collagen fiber thickness, overall cell alignment, and nuclear elongation relative to 10 µm groove depth. This study demonstrates for the first time that scaffolds with combined hierarchical mesoscale and microscale features can align cells in vivo for oral tissue repair with potential for improving the regenerative response of other bone-ligament complexes.

Menarche? A Case of Abdominal Pain and Vaginal Bleeding in a Preadolescent Girl.

Abdominal pain is one of the most common complaints in the pediatric ED. Because of the broad range of potential diagnoses, it can pose challenges in diagnosis and therapy in the preadolescent girl. An 11-year-old previously healthy girl presented to our pediatric ED with fever, decreased appetite, vaginal bleeding, and abdominal pain. Initial evaluation yielded elevated creatinine levels, leukocytosis with bandemia, elevated inflammatory markers, and urine concerning for a urinary tract infection. She began receiving antibiotics for presumed pyelonephritis and was admitted to the hospital. After worsening respiratory status and continued abdominal pain, a computed tomography scan was obtained and a pelvic foreign body and abscess were identified. Adolescent gynecology was consulted for examination under anesthesia for abscess drainage and foreign body removal. A foreign body in the vagina or uterus can present as vaginal discharge, vaginal bleeding, abdominal pain, dysuria, or hematuria. Because symptoms can be diverse, an intravaginal or uterine foreign body should be considered in the preteen female patient presenting to the ED with abdominal pain.

Cell population kinetics of collagen scaffolds in ex vivo oral wound repair.

Biodegradable collagen scaffolds are used clinically for oral soft tissue augmentation to support wound healing. This study sought to provide a novel ex vivo model for analyzing healing kinetics and gene expression of primary human gingival fibroblasts (hGF) within collagen scaffolds. Sponge type and gel type scaffolds with and without platelet-derived growth factor-BB (PDGF) were assessed in an hGF containing matrix. Morphology was evaluated with scanning electron microscopy, and hGF metabolic activity using MTT. We quantitated the population kinetics within the scaffolds based on cell density and distance from the scaffold border of DiI-labled hGFs over a two-week observation period. Gene expression was evaluated with gene array and qPCR. The sponge type scaffolds showed a porous morphology. Absolute cell number and distance was higher in sponge type scaffolds when compared to gel type scaffolds, in particular during the first week of observation. PDGF incorporated scaffolds increased cell numbers, distance, and formazan formation in the MTT assay. Gene expression dynamics revealed the induction of key genes associated with the generation of oral tissue. DKK1, CYR61, CTGF, TGFBR1 levels were increased and integrin ITGA2 levels were decreased in the sponge type scaffolds compared to the gel type scaffold. The results suggest that this novel model of oral wound healing provides insights into population kinetics and gene expression dynamics of biodegradable scaffolds.

Bat-cave catchment areas: using stable isotopes (deltaD) to determine the probable origins of hibernating bats.

The application of stable hydrogen isotope (deltaD) techniques has swiftly advanced our understanding of animal movements, but this progression is dominated by studies of birds and relatively long-distance, north-south migrants. This dominance reflects the challenge of incorporating multiple sources of error into geographic assignments and the nature of spatially explicit deltaD models, which possess greater latitudinal than longitudinal resolution. However, recent progress in likelihood-based assignments that incorporate multiple sources of isotopic error and Bayesian approaches that include additional sources of information may advance finer-scale understanding of animal movements. We develop a stable-isotope method for determining probable origins of bats within hibernacula and show that this method produces spatially explicit, continuous assignments with regional resolution. We outline how these assignments can be used to infer hibernacula connectivity, an application that could inform spatial modeling of white-nose syndrome. Additionally, estimates of seasonal and annual flight distances for many cave-dwelling bat species can be derived from this approach. We also discuss how this application can be used in general to provide insights into variable migratory and foraging strategies within bat populations.