3D genomic mapping reveals multifocality of human pancreatic precancers.

Pancreatic intraepithelial neoplasias (PanINs) are the most common precursors of pancreatic cancer, but their small size and inaccessibility in humans make them challenging to study. Critically, the number, dimensions and connectivity of human PanINs remain largely unknown, precluding important insights into early cancer development. Here, we provide a microanatomical survey of human PanINs by analysing 46 large samples of grossly normal human pancreas with a machine-learning pipeline for quantitative 3D histological reconstruction at single-cell resolution.

Conservative Treatments of Adolescent Idiopathic Scoliosis: Physical Therapists' Perspectives.

This study aimed to examine physical therapists' perspectives in conservative treatments of pediatric patients with adolescent idiopathic scoliosis (AIS). A cross-sectional survey design was used. A validated questionnaire was distributed to physical therapists, and the responses were analyzed.

Three-dimensional genomic mapping of human pancreatic tissue reveals striking multifocality and genetic heterogeneity in precancerous lesions.

Pancreatic intraepithelial neoplasia (PanIN) is a precursor to pancreatic cancer and represents a critical opportunity for cancer interception. However, the number, size, shape, and connectivity of PanINs in human pancreatic tissue samples are largely unknown. In this study, we quantitatively assessed human PanINs using CODA, a novel machine-learning pipeline for 3D image analysis that generates quantifiable models of large pieces of human pancreas with single-cell resolution.

The Bering Strait was flooded 10,000 years before the Last Glacial Maximum.

The cyclic growth and decay of continental ice sheets can be reconstructed from the history of global sea level. Sea level is relatively well constrained for the Last Glacial Maximum (LGM, 26,500 to 19,000 y ago, 26.5 to 19 ka) and the ensuing deglaciation.

Influence of sample volume on nitrate N and O isotope ratio analyses with the denitrifier method.

Rationale: Analyses of the isotope ratios of nitrogen ( N/ N) and oxygen ( O/ O) in nitrate (NO ) with the denitrifier method require relatively high sample volumes at low concentrations (≤1 μM) to afford sufficient analyte for mass spectrometry, resulting in isotopic offsets compared to more concentrated samples of the same isotopic composition.

Methods: To uncover the origins of isotopic offsets, we analyzed the N and O isotope ratios of NO reference materials spanning concentrations of 0.5-20 μM.

Validation of an Age-Appropriate Screening Tool for Female Athlete Triad and Relative Energy Deficiency in Sport in Young Athletes.

Background The purpose of this study was to determine the concurrent validity of a newly created relative energy deficiency in sport (RED-S) specific screening tool (RST) by comparing scores with the validated pre-participation gynecological examination (PPGE). We hypothesized that the investigators would observe no significant difference between the means of the RST and the PPGE survey. Methods This was a crossover study of 39 female subjects who completed both the RST and the PPGE.

The influence of sample matrix on the accuracy of nitrite N and O isotope ratio analyses with the azide method.

Rationale: The isotope ratios of nitrogen ( N/ N) and oxygen ( O/ O) in nitrite (NO ) can be measured by conversion of the nitrite into nitrous oxide (N O) with azide, followed by mass spectrometric analysis of N O by gas chromatography isotope ratio mass spectrometry (GC/IRMS). While applying this method to brackish samples, we noticed that the N and O isotope ratio measurements of NO are highly sensitive to sample salinity and to the pH at which samples are preserved.

Methods: We investigated the influence of sample salinity and sample preservation pH on the N and O isotope ratios of the N O produced from the reaction of NO with azide.

Constraining the Oxygen Isotopic Composition of Nitrate Produced by Nitrification.

Measurements of the stable isotope ratios of nitrogen (N/N) and oxygen (O/O) in nitrate (NO) enable identification of sources, dispersal, and fate of natural and contaminant NO in aquatic environments. The O/O of NO produced by nitrification is often assumed to reflect the proportional contribution of oxygen atom sources, water, and molecular oxygen, in a 2:1 ratio. Culture and seawater incubations, however, indicate oxygen isotopic equilibration between nitrite (NO) and water, and kinetic isotope effects for oxygen atom incorporation, which modulate the NO O/O produced during nitrification.

Isotopic overprinting of nitrification on denitrification as a ubiquitous and unifying feature of environmental nitrogen cycling.

Natural abundance nitrogen and oxygen isotopes of nitrate (δN and δO) provide an important tool for evaluating sources and transformations of natural and contaminant nitrate (NO) in the environment. Nevertheless, conventional interpretations of NO isotope distributions appear at odds with patterns emerging from studies of nitrifying and denitrifying bacterial cultures. To resolve this conundrum, we present results from a numerical model of NO isotope dynamics, demonstrating that deviations in δO vs.

The contamination of commercial 15N2 gas stocks with 15N-labeled nitrate and ammonium and consequences for nitrogen fixation measurements.

We report on the contamination of commercial 15-nitrogen (15N) N2 gas stocks with 15N-enriched ammonium, nitrate and/or nitrite, and nitrous oxide. 15N2 gas is used to estimate N2 fixation rates from incubations of environmental samples by monitoring the incorporation of isotopically labeled 15N2 into organic matter. However, the microbial assimilation of bioavailable 15N-labeled N2 gas contaminants, nitrate, nitrite, and ammonium, is liable to lead to the inflation or false detection of N2 fixation rates.

Eukaryotic assimilatory nitrate reductase fractionates N and O isotopes with a ratio near unity.

In order to (i) establish the biological systematics necessary to interpret nitrogen (N) and oxygen (O) isotope ratios of nitrate ((15)N/(14)N and (18)O/(16)O) in the environment and (ii) investigate the potential for isotopes to elucidate the mechanism of a key N cycle enzyme, we measured the nitrate N and O isotope effects ((15)ε and (18)ε) for nitrate reduction by two assimilatory eukaryotic nitrate reductase (eukNR) enzymes. The (15)ε for purified extracts of NADPH eukNR from the fungus Aspergillus niger and the (15)ε for NADH eukNR from cell homogenates of the marine diatom Thalassiosira weissflogii were indistinguishable, yielding a mean (15)ε for the enzyme of 26.6 ± 0.

Removal of nitrite with sulfamic acid for nitrate N and O isotope analysis with the denitrifier method.

In environmental water samples that contain both nitrate (NO3-) and nitrite (NO2-), isotopic analysis of nitrate alone by all currently available methods requires pretreatment to remove nitrite. Sulfamic acid addition, used previously for this purpose (Wu JP, Calvert SE, Wong CS. Deep-Sea Research Part I - Oceanographic Research Papers 1997; 44: 287), is shown here to be compatible with the denitrifier method for both N and O isotope analysis of nitrate.