The Accuracy of Readily Available Consumer-Grade Oxygen Saturation Monitors in Pediatric Patients.

BACKGROUND: Pulse oximetry measurement is ubiquitous in acute health care settings in high-income countries and is familiar to any parent whose child has been treated in such a setting. Oximeters for home use are readily available online and are incorporated in several smartphones and smartwatches. METHODS: We wished to determine how accurate are oximeters available online that are designated for adult and pediatric use, and the saturation monitor integrated in a smartphone, when used in children, compared to reference, hospital-grade oximeters. We evaluated a fingertip oximeter marketed for children purchased online; an adult fingertip oximeter purchased online; the oximeter integrated in a smartphone; and reference, hospital-grade oximeters. Participants were < 18 y of age. Bland-Altman charts were generated, and the estimated root mean square error (EARMS) was calculated. Rates of failure to obtain a measurement, relationship between device and time to successful measurement, relationship between age and time to successful measurement, and relationship between error (vs the reference device) and age were evaluated for each consumer-grade device. RESULTS: We measured SpO2 in 74 children between 0.1-17.0 y of age. Subjects weighing < 30 kg had a median (interquartile range [IQR]) age of 2 (1.0 month-1.4 y) months, and subjects weighing ≥ 30 kg had a median (IQR) age of 14.3 (11.9-16.2) y. Readings could not be obtained in 7.5, 0, and 38.8% of subjects using the pediatric, adult, and smartphone oximeters, respectively. The time to successful reading had a modest negative correlation with age with the inexpensive adult and pediatric oximeters. The inexpensive pediatric oximeter had an overall negative bias, with a mean difference from the reference device of -4.5% (SD 7.9%) and an error that ranged from > 8% to < 33% the reference device. The EARMS was 7.92%. The inexpensive adult oximeter demonstrated no obvious trend in error in the limited saturation range evaluated of 87-99%. The overall mean difference was -0.7% (SD 2.5%). EARMS was 2.5%. The smartphone oximeter underestimated SpO2 at saturations < 94% and overestimated SpO2 for saturations > 94%. Saturations could read as much as > 4%, or < 17%, than the reference oximeter. The mean difference was -2.9% (SD 5.2%). EARMS was 5.1%. CONCLUSIONS: Our findings suggest that the performance of consumer-grade devices varies considerably by both subject age and device. The pediatric fingertip device and smartphone application we tested are poorly suited for use in infants. The adult fingertip device we tested performed quite well in larger children with relatively normal oxygen saturations, and the pediatric fingertip device performed moderately well in subjects > 1 y of age who weighed < 30 kg. Given the vast number of devices available online and ever-changing technology, research to evaluate nonclinical oximeters will continue to be required.

Structural Analysis of the Ash2L/Dpy-30 Complex Reveals a Heterogeneity in H3K4 Methylation.

Dpy-30 is a regulatory subunit controlling the histone methyltransferase activity of the KMT2 enzymes in vivo. Paradoxically, in vitro methyltransferase assays revealed that Dpy-30 only modestly participates in the positive heterotypic allosteric regulation of these methyltransferases. Detailed genome-wide, molecular and structural studies reveal that an extensive network of interactions taking place at the interface between Dpy-30 and Ash2L are critical for the correct placement, genome-wide, of H3K4me2 and H3K4me3 but marginally contribute to the methyltransferase activity of KMT2 enzymes in vitro. Moreover, we show that H3K4me2 peaks persisting following the loss of Dpy-30 are found in regions of highly transcribed genes, highlighting an interplay between Complex of Proteins Associated with SET1 (COMPASS) kinetics and the cycling of RNA polymerase to control H3K4 methylation. Overall, our data suggest that Dpy-30 couples its modest positive heterotypic allosteric regulation of KMT2 methyltransferase activity with its ability to help the positioning of SET1/COMPASS to control epigenetic signaling.

Recognizing asymmetry in pseudo-symmetry; structural insights into the interaction between amphipathic α-helices and X-bundle proteins.

An α-helix bundle is a small and compact protein fold always composed of more than 2 α-helices that typically run nearly parallel or antiparallel to each other. The repertoire of arrangements of α-helix bundle is such that these domains bind to a myriad of molecular entities including DNA, RNA, proteins and small molecules. A special instance of α-helical bundle is the X-type in which the arrangement of two α-helices interact at 45° to form an X. Among those, some X-helix bundle proteins bind to the hydrophobic section of an amphipathic α-helix in a seemingly orientation and sequence specific manner. In this review, we will compare the binding mode of amphipathic α-helices to X-helix bundle and α-helical bundle proteins. From these structures, we will highlight potential regulatory paradigms that may control the specific interactions of X-helix bundle proteins to amphipathic α-helices. This article is part of a Special Issue entitled: Biophysics in Canada, edited by Lewis Kay, John Baenziger, Albert Berghuis and Peter Tieleman.