Zircon geochemistry from early evolved terranes records coeval stagnant- and mobile-lid tectonic regimes.

Determining the mechanisms by which the earliest continental crust was generated and reworked is important for constraining the evolution of Earth's geodynamic, surface, and atmospheric conditions. However, the details of early plate tectonic settings often remain obscured by the intervening ~4 Ga of crustal recycling. Covariations of U, Nb, Sc, and Yb in zircon have been shown to faithfully reflect Phanerozoic whole-rock-based plate-tectonic discriminators and are therefore useful in distinguishing zircons crystallized in ridge, plume, and arc-like environments, both in the present and in deep time. However, application of these proxies to deciphering tectonic settings on the early Earth has thus far been limited to select portions of the detrital zircon record. Here, we present in situ trace-element and oxygen isotope compositions for magmatic zircons from crystalline crustal rocks of the Acasta Gneiss Complex and the Saglek-Hebron Complex, Canada. Integrated with information from whole-rock geochemistry and zircon U-Pb, Hf, and O isotopes, our zircon U-Nb-Sc-Yb results reveal that melting of hydrated basalt was not restricted to a single tectonomagmatic process during the Archean but was operative during the reworking of Hadean protocrust and the generation of juvenile crust within two cratons, as early as 3.9 Ga. We observe zircon trace-element compositions indicative of hydrous melting in settings that otherwise host seemingly differing whole-rock geochemistry, zircon Hf, and zircon O isotopes, suggesting contemporaneous operation of stagnant-lid (oceanic plateau) and mobile-lid (arc-like) regimes in the early Archean.

Retrospective Application of Sinusoidal Obstruction Syndrome/Veno-occlusive Disease Diagnostic Criteria in a Pediatric Hematopoietic Stem Cell Transplant Cohort.

Sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) posthematopoietic stem cell transplantation (HSCT) is often diagnosed using the modified Seattle (MS) or European Society for Blood and Marrow Transplantation (EBMT) criteria. We hypothesized that strict application of these criteria could affect the timing of diagnosis and incidence of SOS/VOD. We collected data on 215 transplants performed in 184 patients at a single pediatric hematopoietic stem cell transplantation center, which were divided into 3 cohorts. Clinical diagnosis and treatment of SOS/VOD was documented in 13% of transplants (cohort 1). On retrospective review, 49% of transplant events met either MS and/or EBMT criteria, however, were not diagnosed with SOS/VOD (cohort 2); remaining 38% of transplant events did not meet MS or EBMT criteria and were not diagnosed with SOS/VOD (cohort 3). Day+100 overall survival was significantly inferior for cohort 1 (78%) compared with cohorts 2 or 3 (92% and 95%, P=0.01) with no difference between cohorts 2 and 3 (P=0.5). Patients diagnosed with SOS/VOD >day+13 had worse day+100 overall survival when compared with those diagnosed ≤day13 (64.3% and 100%, respectively, P=0.02). This study highlights the value of careful clinical assessment to guide diagnosis and the need to refine diagnostic criteria for SOS/VOD in children.

Evaluation of Commercial Molecular Diagnostic Methods for Detection and Determination of Macrolide Resistance in Mycoplasma pneumoniae.

We evaluated six commercial molecular tests targeting Mycoplasma pneumoniae, namely, the BioFire FilmArray respiratory panel (RP), the Meridian Alethia Mycoplasma Direct, the GenMark ePlex respiratory pathogen panel (RPP), the Luminex NxTAG RPP, the ELITech ELITe InGenius Mycoplasma MGB research use only (RUO) PCR, and the SpeeDx Resistance Plus MP assays. Laboratory-developed PCR assays at the University of Alabama at Birmingham and the Centers for Disease Control and Prevention were used as reference standards. Among 428 specimens, 212 were designated confirmed positives for M. pneumoniae The highest clinical sensitivities were found with the InGenius PCR (99.5%) and the FilmArray RP (98.1%). The Resistance Plus MP identified 93.3% of the confirmed-positive specimens, whereas 83.6, 64.6, and 55.7% were identified by the ePlex RPP, NxTAG RPP, and Mycoplasma Direct assays, respectively. There was no significant difference between the sensitivity of the reference methods and that of the FilmArray RP and InGenius assays, but the remaining four assays detected significantly fewer positive specimens (P < 0.05). Specificities of all assays were 99.5 to 100%. The Resistance Plus MP assay detected macrolide resistance in 27/33 specimens, resulting in a sensitivity of 81.8%. This study provides the first large-scale comparison of commercial molecular assays for detection of M. pneumoniae in the United States and identified clear differences among their performance. Additional studies are necessary to explore the impact of various test performances on patient outcome.

Cytomegalovirus and Epstein-Barr virus infections among pediatric kidney transplant recipients at a center using universal Valganciclovir Prophylaxis.

BACKGROUND: CMV is associated with adverse effects in renal transplant recipients. The objective of this study was to characterize the incidence and timing of CMV and EBV infections in relation to valGCV prophylaxis in a pediatric renal transplant cohort. METHODS: Retrospective cohort of pediatric renal transplant patients given universal valGCV prophylaxis and universal viral surveillance was evaluated. Demographics, prophylaxis, acute rejection, and CMV and EBV infections were abstracted. RESULTS: A total of 92 pediatric renal allograft recipients, 2008-2013, were included. One or more viral infections developed in 77/92 (83.7%) of the patients. EBV was the most common in 62/92 (67%) patients, irrespective of valGCV (82% of episodes occurring on valGCV). CMV DNAemia occurred in 30/92 (33%) patients, 14 episodes (47%) occurring on valGCV. Incidence of breakthrough CMV on prophylaxis was 15% and was associated with persistent DNAemia (OR 7.8, CI:1.6-32.9, P < 0.02). CMV tissue-invasive disease was not seen. CMV syndrome occurred in 10% of the cohort, only in CMV D+ patients, and only one symptomatic breakthrough infection required treatment. Out of 92, 21 (23%) had simultaneous co-infections with 2-3 viruses. CONCLUSIONS: Viral infections in pediatric renal transplant recipients receiving universal valGCV prophylaxis were common. EBV infections were not reduced by valGCV prophylaxis, and nearly half of CMV infections occurred on valGCV. Symptomatic CMV infection while on prophylaxis was rare. valGCV prophylaxis may prevent symptomatic CMV infection but not EBV infection, and frequent CMV surveillance in pediatric renal transplant recipients on prophylaxis may not be necessary.