The formation of aligned fibrous apatite crystals in enamel is predominantly attributed to the involvement of amelogenin proteins. We developed a model to study interactions of matrix proteins with apatite mineral in vitro and tested the hypothesis that amelogenin solubility affects the ability to induce protein-guided mineralization. Crystal growth experiments were performed on fluoroapatite (FAP) glass-ceramics in mineralizing solutions containing recombinant full-length amelogenin (rH174) at different concentrations. Using atomic force microscopy, we observed that mineral precipitated randomly on the substrate, but also formed thin layers (height, 10 nm) on FAP within 24 hrs. This growth pattern was unaffected when 0.4 mg/mL of rH174 was added. In contrast, crystals grew on FAP at a rate up to 20 times higher, at 1.6 mg/mL protein. Furthermore, nanospheres and mineral bound specifically to FAP and aligned in strings approximately parallel to the c-axis of FAP, leading us to the conclusion that amelogenin proteins indeed control direction and rate of growth of apatite in enamel.

BACKGROUND: Specialty societies, including the Infectious Diseases Society of America, strive to address gender and racial inequities in professional advancement. Microaggressions remain a persistent and pervasive barrier to these goals. Nonprofessional speaker introductions are a manifestation of race- and gender-based microaggressions, which have not been previously assessed at IDWeek. We assessed disparities in speaker introductions at IDWeek over a 7-year period that included formal gender equity initiatives introduced in 2016. METHODS: We conducted a retrospective observational study of video-recorded IDWeek speaker introductions from 2013 to 2019. Trained coders reviewed presentation video archives to assess a primary outcome of nonprofessional introductions: when a speakers professional title was not used as the first introduction. We used descriptive statistics, Fisher exact tests, Cochrane-Armitage trend tests, and multivariable logistic regression to characterize relationships between speaker introductions and presentation year, speaker demographics, and speaker-moderator demographic concordance. RESULTS: Of 1940 videos reviewed, 48.9% of IDWeek speakers received nonprofessional introductions during and before 2016 vs 41.5% of speakers after 2016 (P = .0013). There was an increasing linear trend in the frequency of professional introductions by speaker age group from 47.1% for age <40 years to 65.3% for age >60 years (P < .0001). White moderators more frequently used nonprofessional introductions than moderators from backgrounds underrepresented in medicine (47.7% vs 29.1%, P = .0014). Women-men speaker-moderator pairs had more nonprofessional introductions (54.6%, P < .001). CONCLUSIONS: In the largest assessment of microaggressions in speaker introductions at a national medical specialty conference, we highlighted some progress over time and ample opportunity to further standardize equitable speaker introductions, especially for women and junior speakers.

Vancomycin (VAN) and daptomycin (DAP) are approved as a monotherapy for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. A regimen of daptomycin plus ceftaroline (DAP+CPT) has shown promise in published case series of MRSA salvage therapy, but no comparative data exist to compare up-front DAP+CPT head-to-head therapy versus standard monotherapy as an initial treatment. In a pilot study, we evaluated 40 adult patients who were randomized to receive 6 to 8 mg/kg of body weight per day of DAP and 600 mg intravenous (i.v.) CPT every 8 h (q8h) (n = 17) or standard monotherapy (n = 23) with vancomycin (VAN; dosed to achieve serum trough concentrations of 15 to 20 mg/liter; n = 21) or 6 to 8 mg/kg/day DAP (n = 2). Serum drawn on the first day of bacteremia was sent to a reference laboratory post hoc for measurement of interleukin-10 (IL-10) concentrations and correlation to in-hospital mortality. Sources of bacteremia, median Pitt bacteremia scores, Charlson comorbidity indices, and median IL-10 serum concentrations were similar in both groups. Although the study was initially designed to examine bacteremia duration, we observed an unanticipated in-hospital mortality difference of 0% (0/17) for combination therapy and 26% (6/23) for monotherapy (P = 0.029), causing us to halt the study. Among patients with an IL-10 concentration of >5 pg/ml, 0% (0/14) died in the DAP+CPT group versus 26% (5/19) in the monotherapy group (P = 0.057). Here, we share the full results of this preliminary (but aborted) assessment of early DAP+CPT therapy versus standard monotherapy in MRSA bacteremia, hoping to encourage a more definitive clinical trial of its potential benefits against this leading cause of infection-associated mortality. (The clinical study discussed in this paper has been registered at ClinicalTrials.gov under identifier NCT02660346.).