Treatment of Batch in the Detection, Calibration, and Quantification of Immunoassays in Large-scale Epidemiologic Studies

Many laboratory assays measure biomarkers via a 2-stage process. Direct measurement yields relative measures that are subsequently transformed to the unit of interest by using a calibration experiment. The calibration experiment is performed within the main experiment and uses a validation set for which true values are known and relative values are measured by assays to estimate the relation between relative and absolute values. Immunoassays, polymerase chain reaction, and chromatographic approaches are among assays performed in this manner. METHODS: For studies with multiple batches, data from more than a single calibration experiment are available. Conventionally, calibration of assays based on the standard curve is performed specific to each batch; the calibration experiment from each batch is used to calibrate each batch independently. This batch-specific approach incorporates batch variability but, due to the small number of calibration measurements in each batch, may not be best suited for this purpose. RESULTS: Mixed-effects models have been described to address interassay variability and to provide a measure of quality assurance. Conversely, when interbatch variability is negligible, a model that does not incorporate batch effect may be used to estimate an overall calibration curve. CONCLUSION: We explore approaches for use of calibration data in studies with many batches. Using a real data example with biomarker and outcome information, we show that risk estimates may vary depending on the calibration approach used. We demonstrate the potential for bias when using simulations. Under minimal interbatch variability, as seen in our data, conventional batch-specific calibration does not best use information available in the data and results in attenuated risk estimates

Ultrasound modulates neuronal potassium currents via ionotropic glutamate receptors

Background Focused ultrasound stimulation (FUS) has the potential to provide non-invasive neuromodulation of deep brain regions with unparalleled spatial precision. However, the cellular and molecular consequences of ultrasound stimulation on neurons remains poorly understood. We previously reported that ultrasound stimulation induces increases in neuronal excitability that persist for hours following stimulation in vitro. In the present study we sought to further elucidate the molecular mechanisms by which ultrasound regulates neuronal excitability and synaptic function. Objectives To determine the effect of ultrasound stimulation on voltage-gated ion channel function and synaptic plasticity. Methods Primary rat cortical neurons were exposed to a 40 s, 200 kHz pulsed ultrasound stimulus or sham-stimulus. Whole-cell patch clamp electrophysiology, quantitative proteomics and high-resolution confocal microscopy were employed to determine the effects of ultrasound stimulation on molecular regulators of neuronal excitability and synaptic function. Results We find that ultrasound exposure elicits sustained but reversible increases in whole-cell potassium currents. In addition, we find that ultrasound exposure activates synaptic signalling cascades that result in marked increases in excitatory synaptic transmission. Finally, we demonstrate the requirement of ionotropic glutamate receptor (AMPAR/NMDAR) activation for ultrasound-induced modulation of neuronal potassium currents. Conclusion These results suggest specific patterns of pulsed ultrasound can induce contemporaneous enhancement of both neuronal excitability and synaptic function, with implications for the application of FUS in experimental and therapeutic settings. Further study is now required to deduce the precise molecular mechanisms through which these changes occur

Relationship between Type-D personality, physical activity behaviour and climacteric symptoms.

A number of factors have been identified which might influence the variation observed in climacteric symptoms in peri- and post-menopausal women. We examined the role of the distressed or Type-D personality and mode of physical activity or exercise on the climacteric symptoms experienced by peri- or post-menopausal women

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A

On 2017 August 17, the gravitational-wave event GW170817 was observed by the Advanced LIGO and Virgo detectors, and the gamma-ray burst (GRB) GRB 170817A was observed independently by the Fermi Gamma-ray Burst Monitor, and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory. The probability of the near-simultaneous temporal and spatial observation of GRB 170817A and GW170817 occurring by chance is $5.0\times {10}^{-8}$. We therefore confirm binary neutron star mergers as a progenitor of short GRBs. The association of GW170817 and GRB 170817A provides new insight into fundamental physics and the origin of short GRBs. We use the observed time delay of $(+1.74\pm 0.05)\,{\rm{s}}$ between GRB 170817A and GW170817 to: (i) constrain the difference between the speed of gravity and the speed of light to be between $-3\times {10}^{-15}$ and $+7\times {10}^{-16}$ times the speed of light, (ii) place new bounds on the violation of Lorentz invariance, (iii) present a new test of the equivalence principle by constraining the Shapiro delay between gravitational and electromagnetic radiation. We also use the time delay to constrain the size and bulk Lorentz factor of the region emitting the gamma-rays. GRB 170817A is the closest short GRB with a known distance, but is between 2 and 6 orders of magnitude less energetic than other bursts with measured redshift. A new generation of gamma-ray detectors, and subthreshold searches in existing detectors, will be essential to detect similar short bursts at greater distances. Finally, we predict a joint detection rate for the Fermi Gamma-ray Burst Monitor and the Advanced LIGO and Virgo detectors of 0.1-1.4 per year during the 2018-2019 observing run and 0.3-1.7 per year at design sensitivity

Self-collected dried blood spots as a tool for measuring ovarian reserve in young female cancer survivors.

Study questionAre female young cancer survivors (YCS) able to self-collect high-quality dried blood spots (DBSs) at home to provide biospecimens for studying ovarian reserve?Summary answerYCS can self-collect high-quality DBS specimens in non-clinical settings, and anti-Mullerian hormone (AMH) levels can be assayed in such specimens.What is known alreadyLarge-scale biosample collection is a barrier to studying ovarian reserve in YCS. DBS collected by research personnel has high acceptability. AMH levels measured in DBS are highly correlated with those measured by serum-based methods.Study design, size, durationIn a prospective cohort study, YCS were recruited to self-collect DBS samples. AMH levels were assayed in 112 samples.Participants/materials, setting, methodsYCS participants, ages 18-44, were recruited from a nationwide longitudinal cohort and DBS collection materials were posted to them. AMH levels were assayed by the Ansh DBS AMH ELISA and compared according to participant characteristics.Main results and the role of chanceAmong 163 potential participants, 123 (75%) were enrolled. Of those enrolled, 112 (91%) were able to complete DBS self-collection and submit mailed samples adequate for measuring AMH. Participants (mean age 31.6 [SD 5.5]) were 85% white, 87% college graduates and 46% reported higher income. Common cancer types were lymphoma and leukemia (34%), breast cancer (30%) and thyroid or skin cancer (8%). The geometric mean (95% confidence interval) AMH level in DBS samples was 0.24 ng/ml (0.16-0.36). In adjusted analysis, AMH levels for survivors of breast cancer (0.02 ng/ml [0.01-0.07]) or leukemia/lymphoma (0.03 ng/ml [0.01-0.08]) were lower than the levels in thyroid or skin cancer survivors (0.12 ng/ml [0.03-0.44]). Pelvic radiation remained associated with lower AMH levels (0.20 ng/ml [0.10-0.40] in unexposed versus 0.02 ng/ml [0.01-0.06] in exposed). Amenorrheic survivors had AMH levels (0.02 ng/ml [0.01-0.06]) that were lower than those of YCS with 7-9 (0.09 ng/ml [0.03-0.32]) or ≥10 (0.17 ng/ml [0.08-0.37]) menstrual periods in the past year.Limitations, reasons for cautionThe results are generalizable to a population of highly educated, higher income YCS. It is unclear how generalizable the results are to other populations.Wider implications of the findingsSelf-collected DBS is a patient-friendly and minimally invasive tool for studying ovarian reserve in geographically diverse populations.Study funding/competing interestsResearch related to the development of this paper was supported by the National Institutes of Health, grants UL1 RR024926 pilot and HD080952-02, and by the American Cancer Society MRSG-08-110-01-CCE. The authors report no competing interests