Plasma Isotope Research Articles

Unveiling the Origin of Copper Accumulation in Plasma with Aging.

Aging is intricately linked to various diseases including cancers, neurodegenerative disorders, and metabolic irregularities. Copper (Cu) overexposure has been found to be linked to many diseases during aging, particularly neurodegenerative diseases. Meanwhile, as an essential element, Cu has been implicated in key processes associated with aging, raising questions about its role in age-related health issues. This study delves into the mechanisms behind the copper imbalance during aging. By analyzing blood copper concentrations of healthy individuals (including data from healthy subjects (26 ≤ age ≤ 90, n = 62) and publicly available data from the National Health and Nutrition Examination Survey (18 ≤ age < 80, n = 1624)) and employing C57BL/6N male mice models (n = 22), we reveal a consistent age-related increase in copper levels, particularly in plasma. Utilizing stable copper isotopic analysis, copper-associated protein analysis, and metabolomic analysis, we trace the sources of Cu imbalance associated with aging. Our findings reveal that aged mice had a higher copper concentrations and an enrichment of light copper isotope (63Cu) in plasma compared to controls. Additionally, copper reductases and copper transporters are upregulated in the intestine tract, associated with the AMPK and mTOR signaling pathways. We suggest that aged mice have an abnormally high copper intake requirement, probably due to deregulated nutrient sensing, leading to increased expression levels of copper reductases and copper transporters for extra copper absorption in the intestines. This research provides a copper-centric perspective on the connection between deregulated nutrient sensing and aging, thus shedding light on the aspect of aging and copper overexposure.

Assessing Human Iron Kinetics Using Stable Iron Isotopic Techniques.

Stable iron isotope techniques are critical for developing strategies to combat iron deficiency anemia, a leading cause of global disability. There are four primary stable iron isotope methods to assess ferrokinetics in humans. (i) The fecal recovery method applies the principles of a metabolic balance study but offers enhanced accuracy because the amount of iron isotope present in feces can be directly traced back to the labeled dose, distinguishing it from endogenous iron lost in stool from shed intestinal cells. (ii) In the plasma isotope appearance method, plasma samples are collected for several hours after oral dosing to evaluate the rate, quantity, and pattern of iron absorption. Key metrics include the time of peak isotope concentration and the area under the curve. (iii) The erythrocyte iron incorporation method measures iron bioavailability (absorption and erythrocyte iron utilization) from a whole blood sample collected 2 weeks after oral dosing. Simultaneous administration of oral and intravenous tracers allows for separate measurements of iron absorption and iron utilization. These threemethods determine iron absorption by measuring tracer concentrations in feces, serum, or erythrocytes after administration of a tracer. In contrast, (iv) in iron isotope dilution, an innovative new approach, iron of natural composition acts as the tracer, diluting an ad hoc modified isotopic signature obtained via prior isotope administration and equilibration with body iron. This technique enables highly accurate long-term studies of iron absorption, loss, and gain. This review discusses the application of these kinetic methods and their potential to address important questions in hematology andiron biology.

Sustainable H2O2 production via solution plasma catalysis

Clean production of hydrogen peroxide (H2O2) with water, oxygen, and renewable energy is considered an important green synthesis route, offering a valuable substitute for the traditional anthraquinone method. Currently, renewable energy-driven production of H2O2 mostly relies on soluble additives, such as electrolytes and sacrificial agents, inevitably compromising the purity and sustainability of H2O2. Herein, we develop a solution plasma catalysis technique that eliminates the need for soluble additives, enabling eco-friendly production of concentrated H2O2 directly from water and O2. Screening over 40 catalysts demonstrates the superior catalytic performance of carbon nitride interacting with discharge plasma in water. High-throughput density functional theory calculations for 68 models, along with machine learning using 29 descriptors, identify cyano carbon nitride (CCN) as the most efficient catalyst. Solution plasma catalysis with the CCN achieves concentrated H2O2 of 20 mmol L-1, two orders of magnitude higher than photocatalysis by the same catalyst. Plasma diagnostics, isotope labeling, and COMSOL simulations collectively validate that the interplay of solution plasma and the CCN accounts for the significantly increased production of singlet oxygen and H2O2 thereafter. Our findings offer an efficient and sustainable pathway for H2O2 production, promising wide-ranging applications across the chemical industry, public health, and environmental remediation.

Modulating the Activity of the Human Organic Cation Transporter 2 Emerges as a Potential Strategy to Mitigate Unwanted Toxicities Associated with Cisplatin Chemotherapy.

Cisplatin (CDDP) stands out as an effective chemotherapeutic agent; however, its application is linked to the development of significant adverse effects, notably nephro- and ototoxicity. The human organic cation transporter 2 (hOCT2), found in abundance in the basolateral membrane domain of renal proximal tubules and the Corti organ, plays a crucial role in the initiation of nephro- and ototoxicity associated with CDDP by facilitating its uptake in kidney and ear cells. Given its limited presence in cancer cells, hOCT2 emerges as a potential druggable target for mitigating unwanted toxicities associated with CDDP. Potential strategies for mitigating CDDP toxicities include competing with the uptake of CDDP by hOCT2 or inhibiting hOCT2 activity through rapid regulation mediated by specific signaling pathways. This study investigated the interaction between the already approved cationic drugs disopyramide, imipramine, and orphenadrine with hOCT2 that is stably expressed in human embryonic kidney cells. Regarding disopyramide, its influence on CDDP cellular transport by hOCT2 was further characterized through inductively coupled plasma isotope dilution mass spectrometry. Additionally, its potential protective effects against cellular toxicity induced by CDDP were assessed using a cytotoxicity test. Given that hOCT2 is typically expressed in the basolateral membrane of polarized cells, with specific regulatory mechanisms, this work studied the regulation of hOCT2 that is stably expressed in Madin-Darby Canine Kidney (MDCK) cells. These cells were cultured in a matrix to induce the formation of cysts, exposing hOCT2 in the basolateral plasma membrane domain, which was freely accessible to experimental solutions. The study specifically tested the regulation of ASP+ uptake by hOCT2 in MDCK cysts through the inhibition of casein kinase II (CKII), calmodulin, or p56lck tyrosine kinase. Furthermore, the impact of this manipulation on the cellular toxicity induced by CDDP was examined using a cytotoxicity test. All three drugs-disopyramide, imipramine, and orphenadrine-demonstrated inhibition of ASP+ uptake, with IC50 values in the micromolar (µM) range. Notably, disopyramide produced a significant reduction in the CDDP cellular toxicity and platinum cellular accumulation when co-incubated with CDDP. The activity of hOCT2 in MDCK cysts experienced a significant down-regulation under inhibition of CKII, calmodulin, or p56lck tyrosine kinase. Interestingly, only the inhibition of p56lck tyrosine kinase demonstrated the capability to protect the cells against CDDP toxicity. In conclusion, certain interventions targeting hOCT2 have demonstrated the ability to reduce CDDP cytotoxicity, at least in vitro. Further investigations in in vivo systems are warranted to ascertain their potential applicability as co-treatments for mitigating undesired toxicities associated with CDDP in patients.

Characteristic of spatiotemporal evolution of hydrogen isotope in laser-induced plasma under low-pressure environment

The elemental analysis of hydrogen (H) and its isotopes, deuterium (D) and tritium (T) is important for fuel retention detections in plasma-facing materials of nuclear fusion devices, H abundance assessment in geochemistry and so on. Laser-induced breakdown spectroscopy (LIBS) is one of the most promising technology to analyze the H isotopes due to its excellent real-time and in situ analytical ability. However, the laser ablation plasma is a transient plasma with inhomogeneous spatiotemporal evolution. Especially in low-pressure background, the particles with different masses may separate in the plasma plume. This will result in the loss of accuracy of LIBS measurement. In this work, the characteristic of spatiotemporal evolution of spectra from laser-induced plasma on the frozen D2O-H2O mixture under low-pressure environment has been investigated. The spectral intensity of Dα and electron density decrease with radial direction and delay time. The intensities ratio of Dα and Hα, ID/(ID + IH), are almost constant at different radial positions and delay times under the background pressure of 1 × 10−1 mbar. However, when the pressure decreases to 1 × 10−4 mbar, ID/(ID + IH) decreases from the center to the edge of the plasma due to plume separation by the different atomic masses of isotopes. The degree of separation increases from the center to the edge of the plasma. The results will be useful for better understanding of characteristic of spatiotemporal evolution of LIBS plasma in low pressure and improvement of LIBS measurement for H isotopes.

Precolumn derivatization LC-MS/MS method to simultaneous quantitation of 10 monosaccharides in rat plasma

Monosaccharides are essential for maintaining the normal physiological functions of living organisms. Under disease states, metabolic disorders in vivo will inevitably affect the levels of monosaccharides, which brings the possibility of monosaccharides as a biomarker of some diseases. In this study, a method was developed and validated for simultaneously determining 10 monosaccharides (glucose, galactose, mannose, rhamnose, fucose, xylose, iduronic acid, glucuronic acid, N-acetylgalactosamine and N-acetylglucosamine) in SD rat plasma using liquid chromatography-tandem mass spectrometry. The method employed 1-phenyl-3-methyl-5-pyrazolone (PMP) as a derivatization reagent, considerably improved the chromatographic retention and ionization efficiency of monosaccharides. After protein precipitation of plasma samples, monosaccharides and isotope internal standards were derivatized and liquid-liquid extraction was performed to remove excess PMP. To achieve the baseline separation of several isomers, the resulting derivatives were chromatographed on a Bridged ethyl hybrid (BEH) Phenyl column using gradient elution with a total run time of 8 min. The method was linear within the range of 0.0100–5.00 μg/mL for rhamnose, 0.0500–25.0 μg/mL for fucose, xylose, iduronic acid, glucuronic acid, N-acetylgalactosamine and N-acetylglucosamine, 1.00–500 μg/mL for galactose, 10.0–5000 μg/mL for mannose, and 50.0–25,000 μg/mL for glucose. And the accuracy and precision verification of surrogate matrix samples and plasma samples met the required criteria. The method has been used successfully to study the effect of hepatic insufficiency on monosaccharide levels in rats. It was found that the concentration of glucuronic acid in SD rat plasma was abnormally increased in rats with liver injury.

Feldspar Pb isotope evidence of cryptic impact-driven hydrothermal alteration in the Paleoproterozoic

Hypervelocity impacts throughout Earth's history have profoundly affected the evolution of the continental crust. Accessory minerals like zircon are typically used to date impact events and rock-forming minerals like quartz are routinely used as shock barometers. However, feldspar group minerals – a major constituent of most crustal rocks – are generally underutilized in the documentation of impact-induced deformation and alteration. Alkali feldspar contains appreciable amounts of Pb and analysis of Pb isotopes in feldspar may offer the opportunity to identify impact-related isotopic modifications of shocked crustal target rocks and estimate their timing. Here, we apply a combination of laser ablation inductively coupled plasma (LA-ICP) and thermal ionization mass spectrometry (TIMS) Pb isotope analysis with imaging techniques, including electron backscatter diffraction (EBSD), cathodoluminescence (CL), and time of flight secondary ion mass spectrometry (ToF-SIMS), to shocked alkali feldspar from monzogranite in the oldest confirmed terrestrial impact structure (2229 ± 5 Ma) at Yarrabubba, Western Australia. Alkali feldspar preserves microstructures such as sub-planar and irregular fractures, sets of planar deformation bands that accommodate misorientations of up to ∼20°, sets of damage lamellae, and broad domains of lattice damage that can be linked to impact-related deformation. The Pb isotope compositions in alkali feldspar correlate with variations in electron diffraction band contrast – a proxy for crystallinity – and also the degree of misorientation and CL response. Less damaged alkali feldspar yields Pb model ages similar to the igneous zircon U–Pb crystallization age of the host monzogranite (∼2650 Ma), whereas younger Pb model ages correspond to zones of damage (high relative misorientation, low crystallinity, weak CL response). The observed Pb isotope behaviour implies radiogenic ingrowth of Pb, from decay of U and Th within damaged alkali feldspar, and therefore mixing with a grain-scale Pb reservoir that formed at the time of impact. The U and Th zonation in some shock-deformed alkali feldspar is broadly similar and follows the orientation of sub-planar fractures and damage lamellae. Detailed imaging reveals the zones of U and Th enrichment are associated with trains of monazite micro-inclusions, in conjunction with magnetite and/or hematite in places, which are inferred to have precipitated during impact-induced hydrothermal circulation. Hence, the Pb isotopic data record grain-scale hydrothermal alteration in superficially weakly altered monzogranite target rocks.

Slc39a4 in the small intestine predicts zinc absorption and utilization: a comprehensive analysis of zinc transporter expression in response to diets of varied zinc content in young mice

Zinc homeostasis is primarily maintained by zinc transporters that regulate zinc uptake and efflux in the small intestine; however, the relative contribution of the many zinc transporters identified (Slc39a1-14, Slc30a1-10) to dietary zinc absorption and utilization remains unknown. The objective of this study was to determine the expression of Slc39a1-14 and Slc30a1-10 in the small intestine and their relative contribution to dietary zinc absorption in mice. Five-week-old male C57BL/6J mice were fed modified AIN-93G diets containing <1, 30, or 100ppm zinc (n=15 mice/diet). Following 1 week of feeding, mice were given an oral gavage containing 67Zn and liver and plasma isotope appearance was determined 6-h later by ICP-MS. Expression of Slc39a1-14 and Slc30a1-10 was determined in mucosa from duodenum, jejunum, and ileum. Plasma and liver total zinc concentrations were not different after one week of feeding (P>.05). Liver and plasma appearance of 67Zn was greater in mice fed <1ppm compared to the 30ppm (P<.0001) and 100ppm (P<.0001) zinc diets. With the exception of Slc39a2, Slc39a12, Slc30a3, and Slc30a8, the remaining zinc transporters were expressed across all diets and intestinal segments. Expression of Slc39a4, Slc39a11, and Slc30a6 changed with diet (Pdiet<.05 for all); expression of Slc39a5, Slc39a7, Slc39a11, Slc39a14, Slc30a1, Slc30a2, Slc30a4, Slc30a5, Slc30a7, and Slc30a10 changed by intestinal segment (Psegment<.05 for all). Slc39a4 was the only transporter positively associated with liver (r2=0.316, P<.001) and plasma (r2=0.189, P<.01) 67Zn appearance. Although most zinc transporters are expressed in the small intestine, intestinal Slc39a4 predicts fractional zinc absorption and utilization in young mice.

Review of Element Analysis of Industrial Materials by In-Line Laser—Induced Breakdown Spectroscopy (LIBS)

Laser-induced breakdown spectroscopy (LIBS) is a rapidly developing technique for chemical materials analysis. LIBS is applied for fundamental investigations, e.g., the laser plasma matter interaction, for element, molecule, and isotope analysis, and for various technical applications, e.g., minimal destructive materials inspection, the monitoring of production processes, and remote analysis of materials in hostile environment. In this review, we focus on the element analysis of industrial materials and the in-line chemical sensing in industrial production. After a brief introduction we discuss the optical emission of chemical elements in laser-induced plasma and the capability of LIBS for multi-element detection. An overview of the various classes of industrial materials analyzed by LIBS is given. This includes so-called Technology materials that are essential for the functionality of modern high-tech devices (smartphones, computers, cars, etc.). The LIBS technique enables unique applications for rapid element analysis under harsh conditions where other techniques are not available. We present several examples of LIBS-based sensors that are applied in-line and at-line of industrial production processes.

Old subcontinental mantle zircon below Oahu

Our understanding of mantle evolution suffers from a lack of age data for when the mantle geochemical variants (mantle components) developed. Traditionally, the components are ascribed to subduction of ocean floor over Earth history, but their isotopic signatures require prolonged storage to evolve. Here we report U-Pb age results for mantle-derived zircon from pyroxenite xenoliths in Oahu, Hawaii, using laser ablation inductively coupled plasma mass spectrometry and isotope dilution - thermal ionization mass spectrometry. The zircon grains have 14 million-year-old rims, Cretaceous cores, and Proterozoic Lu-Hf model ages which are difficult to reconcile with transport of the pyroxenites in the Hawaiian mantle plume because the ages would have been reset by high temperatures. We suggest the zircons may have been preserved in sub-continental lithospheric mantle. They possibly reached Oahu by asthenospheric transport after subduction at Papua New Guinea or may represent fragments of sub-continental lithospheric mantle stranded during Pangean breakup.

Improving the accuracy of chloride measurements through participation in regular external quality assessment programme

BackgroundA chloride test is an integral part of a basic metabolic panel that is essential for the assessment of a patient’s acid-base and electrolyte status. While many methods are available commercially for the routine measurement of chloride, there is a need to address the accuracy and variability among the measurement results, especially with the prevalence of patients seeking treatment across different healthcare providers for alternative opinions. MethodA method based on sector field inductively coupled plasma isotope dilution mass spectrometry (SF-ICP-IDMS) was developed for the measurement of chloride in human serum. The SF-ICP-IDMS method was then used to assign the target values in the Health Sciences Authority (HSA) External Quality Assessment (EQA) Programme to evaluate the results of chloride test from participating clinical laboratories. ResultsThe accuracy of the measurements was evaluated by comparing the results with the certified values of Electrolytes in Frozen Human Serum Certified Reference Materials (SRM 956c and SRM 956d) from the National Institute of Standards and Technology (NIST) at different chloride concentration levels. Over a five-year period from 2014–2018, the number of clinical laboratories which participated in the EQA Programme increased from 23 to 33. Comparison of robust means from the laboratories’ results with our assigned target values revealed a reduction in relative deviation over time. The relationship between the deviation of each brand of clinical analysers and the chloride levels was established, where a larger deviation was uncovered at low chloride concentration. The SF-ICP-IDMS method was further demonstrated to be comparable with methods used by other metrology institutes in an international comparison organised by HSA under the auspice of the Consultative Committee for Amount of Substance – Metrology in Chemistry and Biology (CCQM). ConclusionThe use of metrologically traceable assigned target values enabled the study of method biasness from a small pool of dataset in each of the four brands of clinical analysers in HSA EQA Programme. This work underscores the need to improve the accuracy of chloride measurements by regular participation in an accuracy-based EQA Programme.

Spatial characterization of edge zonal flows in the TJ-II stellarator: the roles of plasma heating and isotope mass

In this article, we report the latest results for the impacts of the isotope mass and the plasma heating scenario on the spatiotemporal characteristics of the low-frequency zonal flow (ZF)-like electrostatic oscillation found in the plasma edge of the TJ-II stellarator. The radial profile of the toroidal cross-coherence in low-frequency floating potential fluctuations (1 < f < 25 kHz), known as long-range correlations (LRCs), was explored along the plasma boundary region by a dual Langmuir probe system. The study was performed using electron cyclotron resonance heating (ECRH)- and neutral beam injection (NBI)-heated plasmas with two different isotope concentrations: pure hydrogen plasmas and plasmas dominated by deuterium (). The highest toroidal coherence levels are detected for floating potential oscillations at less than 10 kHz in hydrogen and deuterium plasmas, in both the ECRH and NBI heating schemes. The radial extent of the LRC profile is clearly larger in the ECRH than in the NBI-heated plasma scenarios. While the maximum amplitude of the LRC does not show a significant dependence on isotope mass, the relation between the LRCs’ radial sizes in plasmas and different isotope masses increases with the isotope mass in NBI-heated scenarios. These results provide the first experimental observation of ZFs with a larger radial size in deuterium than in hydrogen plasmas.

Energy deficit increases hepcidin and exacerbates declines in dietary iron absorption following strenuous physical activity: a randomized-controlled cross-over trial

Strenuous physical activity promotes inflammation and depletes muscle glycogen, which may increase the iron regulatory hormone hepcidin. Hepcidin reduces dietary iron absorption and may contribute to declines in iron status frequently observed following strenuous physical activity. To determine the effects of strenuous physical activity on hepcidin and dietary iron absorption and whether energy deficit compared with energy balance modifies those effects. This was a randomized, cross-over, controlled-feeding trial in healthy male subjects (n=10, mean±SD age: 22.4±5.4 y, weight: 87.3±10.9 kg) with sufficient iron status (serum ferritin 77.0±36.7 ng/mL). Rest measurements were collected before participants began a 72-h simulated sustained military operation (SUSOPS), designed to elicit high energy expenditure, glycogen depletion, and inflammation, followed by a 7-d recovery period. Two 72-h SUSOPS trials were performed where participants were randomly assigned to consume either energy matched (±10%) to their individual estimated total daily energy expenditure (BAL) or energy at 45% of total daily energy expenditure to induce energy deficit (DEF). On the rest day and at the completion of BAL and DEF, participants consumed a beverage containing 3.8 mg of a stable iron isotope, and plasma isotope appearance was measured over 6 h. Muscle glycogen declined during DEF and was preserved during BAL (-188±179 mmol/kg, P-adjusted<0.01). Despite similar increases in interleukin-6, plasma hepcidin increased during DEF but not BAL, such that hepcidin was 108% greater during DEF compared with BAL (7.8±12.2 ng/mL, P-adjusted<0.0001). Peak plasma isotope appearance at 120 min was 74% lower with DEF (59±38% change from 0 min) and 49% lower with BAL (117±81%) compared with rest (230±97%, P-adjusted<0.01 for all comparisons). Strenuous physical activity decreases dietary iron absorption compared with rest. Energy deficit exacerbates both the hepcidin response to physical activity and declines in dietary iron absorption compared with energy balance. This trial was registered at clinicaltrials.gov as NCT03524690.

Первые результаты комплексных исследований современных микроорганизмов физико-химическими и минералого-геохимическими методами

We studied 14 samples of gram-negative and gram-positive bacteria, unicellular yeasts and green algae using optical, atomic force and analytical scanning electron microscopy, thermal analysis, gas chromatography, infrared spectroscopy, inductively coupled plasma mass spectrometry and isotope mass spectrometry. In shape, the cells of microorganisms vary from rod-shaped to lenticular and coccoid, in size they range from mesonanometer to micrometer. A strong positive correlation was found between the extreme cell sizes. An admixture of inorganic chemical elements — Mg, Ca, Ba, Na, K, Cu, Zn, P, S, Cl and submicron-sized precipitates of mineral phases — carbonates, phosphate sulfates, hydrogen sulfate phosphates, hydrogen phosphates, halite, kaolinite, was found in the chemical composition of the studied microorganisms, metal alloys of brass composition, baddeleyite. Among the 45 microelements identified in microorganisms, there were 7 essential elements (E), 17 physiogenically active (FA) and 19 abiotic (AB). The total concentration of trace elements ranged from 0.003—0.26 wt. %. The value of the essential coefficient — E / AB — averaged 196 ± 153. Microorganisms were characterized by a mixed fat-protein elemental composition, they contained 14 amino acids belonging to the aliphatic, aromatic, basic, acidic, hydroxyl, imino and sulfur-containing groups. The total amino acid content ranged from 409 to 942 (682 ± 221) mg/g. Up to half of the amino acids were represented by the left (L) and right (D) enantiomers. The degree of racemization (D / L) ranged from 0.01 to 0.37. Yeast and chlorella were characterized by the most isotopically heavy composition of carbon in combination with relatively isotopically light nitrogen. In bacteria, a statistically lighter carbon was found in combination with a much heavier nitrogen. According to a number of properties — the chemical composition of organic matter, microelements, the degree of enrichment with antibiotic elements, the content of amino acids and the degree of their racemization — gram-negative and gram-positive bacteria differed. In general, the studied biological microorganisms were fundamentally different from the abiogenic organic substances found in meteorites and products of modern volcanism regarding their elemental and amino acid composition, carbon and nitrogen isotopes.

Thermally driven countercurrent plasma centrifuge

ABSTRACT Renewed interest in plasma isotope separation stems from the need to produce certain isotopes more inexpensively. These include isotopes of groups I and II, rare earth and some other elements of the periodic table. While gas centrifuge cascades, developed for uranium enrichment, are capable of a wider range of separation applications, they are limited to elements that can form volatile gaseous compounds at room temperature. In the absence of a suitable compound, more expensive separation techniques are used, consuming considerable electrical power for relatively low throughputs. We believe that a new type of plasma centrifuge can be a viable alternative.

Stable isotope analysis of multiple tissues from Hawaiian honeycreepers indicates elevational movement.

We have limited knowledge of the patterns, causes, and prevalence of elevational migration despite observations of seasonal movements of animals along elevational gradients in montane systems worldwide. While a third of extant Hawaiian landbird species are estimated to be elevational migrants this assumption is based primarily on early naturalist's observations with limited empirical evidence. In this study, we compared stable hydrogen isotopes (δ2H) of metabolically inert (feathers) and active (blood plasma, red blood cells) tissues collected from the same individual to determine if present day populations of Hawaiian honeycreepers undergo elevational movements to track areas of seasonally high flower bloom that constitute significant food resources. We also measured stable carbon isotopes (δ13C) and stable nitrogen isotopes (δ15N) to examine potential changes in diet between time periods. We found that the majority of 'apapane (Himatione sanguinea) and Hawai'i 'amakihi (Chlorodrepanis virens) captured at high elevation, high bloom flowering sites in the fall were not year-round residents at the capture locations, but had molted their feathers at lower elevations presumably in the summer after breeding. δ2H values of feathers for all individuals sampled were higher than blood plasma isotope values after accounting for differences in tissue-specific discrimination. We did not find a difference in the propensity of elevational movement between 'apapane and Hawai'i 'amakihi, even though the 'amakihi is considered more sedentary. However, consistent with a more generalist diet, δ15N values indicated that Hawai'i 'amakihi had a more diverse diet across trophic levels than 'apapane, and a greater reliance on nectar in the fall. We demonstrate that collecting multiple tissue samples, which grow at different rates or time periods, from a single individual can provide insights into elevational movements of Hawaiian honeycreepers over an extended time period.

Vitamin A Absorption Determined in Rats Using a Plasma Isotope Ratio Method

ABSTRACTBackgroundBetter methods are needed for determining vitamin A absorption efficiency.ObjectiveOur objective was to measure vitamin A absorption in rats by adapting a plasma isotope ratio method previously used to determine cholesterol absorption.MethodsMale Sprague-Dawley rats [n = 14; 340 ± 16 g (mean ± SD)] received an oral tracer dose of [3H]retinyl acetate in oil plus an intravenous dose of [14C]vitamin A–labeled lymph prepared in a donor rat that had received [14C]retinyl acetate intraduodenally. Blood samples were collected on days 1, 2, 3, 6, 9, and 12, and plasma was analyzed for 3H and 14C; vitamin A absorption was calculated for each sample as (fraction of oral dose/fraction of intravenous dose) × 100. Radioactivity was also measured in feces and urine collected as pools on days 3, 6, 9, and 12 and in liver and remaining carcass on day 12.ResultsVitamin A absorption calculated as the plasma isotope ratio was >100% on day 1, 78% ± 5% on day 6, 76% ± 5% on day 9, and 74% ± 5% on day 12; fitting the data to an exponential function plus a constant predicted an absorption of 75% by day 14. Recovery of the oral dose in feces (day 0 to day 6) was low (6.2% ± 0.84%, n = 10) and the mean isotope ratio in day 9–12 urine pool was lower than that in plasma.ConclusionsThe plasma isotope ratio holds promise for estimating vitamin A absorption, but additional work is needed to determine how long studies need to be and if the doses should be administered simultaneously. For application of this method in humans, artificial chylomicrons labeled with a stable isotope of retinyl acetate could be used for the intravenous dose, with a different isotope required for the oral dose.

The Effects of Short-Term Zinc Feeding on Zinc Absorption and Zinc Transporter Expression in the Small Intestine of Mice

Abstract Objectives Zinc homeostasis is primarily maintained by zinc transporters that regulate zinc uptake and efflux in the small intestine; however, no study to date has comprehensively examined zinc transporter expression in the small intestine of mice fed varying levels of dietary zinc. The objective of this study was to determine the effects of zinc absorption and zinc transporter expression in the small intestine of mice fed varying levels of zinc for one week. Methods Seven-week-old male C57BL/6 J mice were randomized to either a standard AIN-93 G diet containing 30 ppm zinc (zinc adequate) or modified AIN-93 G diets containing &amp;lt;1 ppm (zinc deficient) or 100 ppm zinc (zinc supplemented) for one week (n = 5–10/diet). Mice were given an oral gavage containing a slurry of zinc deficient feed and 10 μg 67 Zn; plasma isotope appearance was determined 6-h later by ICP-MS. Gene expression of Slc39a1–14 and Slc30a1–10 was determined in each intestinal segment (duodenum, jejunum, and ileum) by RT-qPCR. Results Plasma and liver zinc concentrations were not different after one week of feeding (P &amp;gt; 0.05 for both). Plasma appearance of 67 Zn was greater in mice fed the zinc deficient (mean ± SD: 0.36 ± 0.03 ng/mL) compared to the zinc adequate (0.22 ± 0.03 ng/mL) and zinc supplemented (0.22 ± 0.03 ng/mL, P &amp;lt; 0.0001 for both) diets. With the exception of Slc39a12, Slc30a3, and Slc30a8, the remaining zinc transporters were expressed across all diets and intestinal segments. Expression of Slc39a1, Slc39a4, Slc39a5, Slc39a7, Slc39a9, Slc39a11, Slc39a14, Slc30a2, Slc30a4, Slc30a5, Slc30a6, and Slc30a9 changed with diet (Pdiet &amp;lt; 0.05 for all); expression of Slc39a3, Slc39a7, Slc39a9 and Slc30a5 changed by intestinal segment (Psegment &amp;lt; 0.05 for all). Of those transporters expressed, Slc39a4 was positively associated with plasma appearance of 67 Zn (r = 0.645, P &amp;lt; 0.0001) and increased 7-fold in mice consuming the zinc deficient diet compared to the zinc adequate and zinc supplemented diets (P &amp;lt; 0.0001 for both). Conclusions Although most zinc transporters are expressed in the small intestine and likely function in concert, fluctuations in fractional zinc absorption are positively correlated with Slc39a4 expression in the small intestine. Funding Sources The views expressed herein are those of the authors and do not reflect official policy of the Army, DoD, or US Government. Supported by MRDC.

Declines in Dietary Iron Absorption Following Simulated Military Operations Are Exacerbated by Energy Deficit

Abstract Objectives Iron status declines with military training; however, the reason for the decline is not known. The objective of this study was to determine whether dietary iron absorption is reduced following military training and whether energy deficit during training modifies the effect. Methods This was a randomized, cross-over, controlled-feeding trial in healthy, active duty military males (n = 10, age 22.4 ± 5.4 y, weight 87.3 ± 10.9 kg) with normal iron status (serum ferritin 77.0 ± 36.7 ng/mL). Following a rest day (no exercise), participants completed a 72-h simulated sustained military operations (SUSOPS) followed by a 7-d recovery period. SUSOPS was comprised of military tasks designed to elicit high energy expenditures, muscle damage, and sleep deprivation. During SUSOPS, participants were randomized to consume ± 10% of estimated total daily energy expenditure (BAL) or 45% of total daily energy expenditure to induce severe negative energy balance (NEG BAL), but an equivalent amount of dietary iron. Two hours after rest, BAL, and NEG BAL participants consumed a beverage containing 3.8 mg of a stable iron isotope and plasma isotope appearance and hepcidin were determined 0, 20, 40, 60, 120, 240, and 360 min later. Results BAL maintained weight (−0.03 ± 0.8 kg) and muscle glycogen (4.1 ± 68.1% change), while NEG BAL lost weight (−2.38 ± 1.7 kg, P &amp;lt; 0.01) and muscle glycogen (−47.6 ± 17.8% change, P = 0.08) during SUSOPS. C-reactive protein (rest 1.2 ± 0.9, BAL 4.7 ± 3.6, NEG BAL 4.8 ± 3.5 mg/L, Pphase &amp;lt; 0.001) increased with SUSOPS compared to rest regardless of energy balance. Peak plasma isotope appearance at 120 min was 49% lower with BAL (116.9 ± 81.4% change from 0 min) and 74% lower with NEG BAL (58.9 ± 38.1%) compared to rest (229.7 ± 97.3%, P &amp;lt; 0.01 for all comparisons). Plasma hepcidin was not different at 0 min (rest 7.2 ± 1.6, BAL 6.7 ± 2.4, NEG BAL 6.8 ± 1.7 ng/mL, P = 0.79) and peaked at 360 min (rest 19.4 ± 9.5, BAL 9.5 ± 4.7, NEG BAL 13.7 ± 8.9 ng/mL, P = 0.03). Conclusions Dietary iron absorption is reduced following SUSOPS in healthy males with normal iron status and the reduction is exacerbated with energy deficit. Circulating concentrations of hepcidin following 72-h SUSOPS do not appear to mediate the reduction in dietary iron absorption. Funding Sources The views expressed are those of the authors and do not reflect official policy of the Army, DoD, or US Government. Supported by MRDC.

Preliminary Study on Characterization of Edible Oils Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Isotope Ratio Mass Spectrometry (IRMS)

In recent years, increasing attention has been paid to oils consumed by humans. The human body uses oils in the diet for three purposes: energy source, structural component and powerful biological regulators. Elemental profiling of macro-, essential elements constitutes an important tool for quality control in terms of nutritional values of these products. Regarding this, Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) determinations were performed to assess the quantitative complement of essential mineral and toxic metals content of different edible oil types, from Romania market, summing 33 samples, after microwave digestion. Additionally, the carbon stable isotope ratios (13C) were determined by Isotope Ratio Mass Spectrometry (IRMS) in order to differentiate the specific fingerprint of investigated oils.