Previous studies have demonstrated the potential for large errors to occur when analyzing waters containing organic contaminants using isotope ratio infrared spectroscopy (IRIS). In an attempt to address this problem, IRIS manufacturers now provide post-processing spectral analysis software capable of identifying samples with the types of spectral interference that compromises their stable isot...

Here we provide the geochemical dataset that our research group has collected after 10 years of investigation in the Sierra Nevada National Park in southern Spain. These data come from Holocene sedimentary records from four alpine sites (ranging from ∼2500 to ∼3000 masl): two peatlands and two shallow lakes. Different kinds of organic and inorganic analyses have been conducted. The organic matt...

It is currently controversial whether mucosal hyperproliferation is involved in colorectal cancerogenesis. The purpose of the present study was to examine protein synthetic rate as an indicator of potential tissue proliferation in grossly normal rectal mucosa from cancer-bearing subjects and to compare this rate with that in mucosa from subjects posttumor removal. Six postabsorptive patients wi...

Continuous flow analysis using an elemental analyzer interfaced with an isotope ratio mass spectrometer (EA-IRMS) is faster and requires much less material than conventional analytical methods. Although using an EA-IRMS is simple and fast, accurate calibration strongly depends on matching sample and reference peak heights by adjusting the sample weight. This paper describes a new modification f...

Quantification of muscle protein synthesis (MPS) remains a cornerstone for understanding the control of muscle mass. Traditional [(13)C]amino acid tracer methodologies necessitate sustained bed rest and intravenous cannulation(s), restricting studies to ~12 h, and thus cannot holistically inform on diurnal MPS. This limits insight into the regulation of habitual muscle metabolism in health, agi...

BACKGROUND Carbon isotope ratio methods are used in doping control to determine whether urinary steroids are endogenous or pharmaceutical. METHODS Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) was used to determine the delta(13)C values for 5 beta-androstane-3 alpha,17 beta-diyl diacetate (5 beta A), 5 alpha-androstane-3 alpha,17 beta-diyl diacetate (5 alpha A), an...

We present a new method for analyzing the delta(13)C isotopic composition of several oxygenated volatile organic compounds (OVOCs) from direct sources and ambient atmospheric samples. Guided by the requirements for analysis of trace components in air, a gas chromatograph isotope ratio mass spectrometer (GC-IRMS) system was developed with the goal of increasing sensitivity, reducing dead-volume ...

Stable hydrogen-isotope ratios (deltaD) of keratin provide a novel means for tracking geographical movements of birds and other species. Here we describe a rapid, low cost, analytical approach to facilitate online continuous-flow isotope-ratio mass spectrometry (CF-IRMS) deltaD analyses of keratins (120-160 samples per day) through the use of calibrated keratin working standards and "comparativ...

Prospective epidemiologic studies generally rely on 1 baseline biologic sample from participants for measurement of prediagnostic biomarkers, assuming that 1 measurement adequately represents the participant's "typical" level. The body of work assessing the reproducibility of circulating serum 25-hydroxyvitamin D (25(OH)D) levels over time focuses almost exclusively on populations of European d...

In the current context of finding plant alternatives to animal proteins, pea would be a good option regarding its high protein content and well-balanced amino acid (AA) profile. However, we must examine digestibility, main criteria nutritional quality. The aim this study was determine real ileal AA nitrogen (N) digestibility (RIDAA RIDN) as compared milk casein in humans. We also evaluated thei...