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Rao VS, Ivey-Miranda JB, Cox ZL, Moreno-Villagomez J, Maulion C, Bellumkonda L, Chang J, Field MP, Wiederin DR, Butler J, Collins SP, Turner JM, Wilson FP, Inzucchi SE, Wilcox CS, Ellison DH, Testani JM. Empagliflozin in Heart Failure: Regional Nephron Sodium Handling Effects. J Am Soc Nephrol 2024; 35:189-201. [PMID: 38073038 PMCID: PMC10843196 DOI: 10.1681/asn.0000000000000269] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 10/25/2023] [Indexed: 02/02/2024] Open
Abstract
SIGNIFICANCE STATEMENT The effect of sodium-glucose cotransporter-2 inhibitors (SGLT2i) on regional tubular sodium handling is poorly understood in humans. In this study, empagliflozin substantially decreased lithium reabsorption in the proximal tubule (PT) (a marker of proximal tubular sodium reabsorption), a magnitude out of proportion to that expected with only inhibition of sodium-glucose cotransporter-2. This finding was not driven by an "osmotic diuretic" effect; however, several parameters changed in a manner consistent with inhibition of the sodium-hydrogen exchanger 3. The large changes in proximal tubular handling were acutely buffered by increased reabsorption in both the loop of Henle and the distal nephron, resulting in the observed modest acute natriuresis with these agents. After 14 days of empagliflozin, natriuresis waned due to increased reabsorption in the PT and/or loop of Henle. These findings confirm in humans that SGLT2i have complex and important effects on renal tubular solute handling. BACKGROUND The effect of SGLT2i on regional tubular sodium handling is poorly understood in humans but may be important for the cardiorenal benefits. METHODS This study used a previously reported randomized, placebo-controlled crossover study of empagliflozin 10 mg daily in patients with diabetes and heart failure. Sodium handling in the PT, loop of Henle (loop), and distal nephron was assessed at baseline and day 14 using fractional excretion of lithium (FELi), capturing PT/loop sodium reabsorption. Assessments were made with and without antagonism of sodium reabsorption through the loop using bumetanide. RESULTS Empagliflozin resulted in a large decrease in sodium reabsorption in the PT (increase in FELi=7.5%±10.6%, P = 0.001), with several observations suggesting inhibition of PT sodium hydrogen exchanger 3. In the absence of renal compensation, this would be expected to result in approximately 40 g of sodium excretion/24 hours with normal kidney function. However, rapid tubular compensation occurred with increased sodium reabsorption both in the loop ( P < 0.001) and distal nephron ( P < 0.001). Inhibition of sodium-glucose cotransporter-2 did not attenuate over 14 days of empagliflozin ( P = 0.14). However, there were significant reductions in FELi ( P = 0.009), fractional excretion of sodium ( P = 0.004), and absolute fractional distal sodium reabsorption ( P = 0.036), indicating that chronic adaptation to SGLT2i results primarily from increased reabsorption in the loop and/or PT. CONCLUSIONS Empagliflozin caused substantial redistribution of intrarenal sodium delivery and reabsorption, providing mechanistic substrate to explain some of the benefits of this class. Importantly, the large increase in sodium exit from the PT was balanced by distal compensation, consistent with SGLT2i excellent safety profile. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER ClinicalTrials.gov ( NCT03027960 ).
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Affiliation(s)
- Veena S. Rao
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Juan B. Ivey-Miranda
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Hospital de Cardiologia, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | - Zachary L. Cox
- Department of Pharmacy Practice, Lipscomb University College of Pharmacy, Nashville, Tennessee
- Department of Pharmacy, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Julieta Moreno-Villagomez
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Facultad de Estudios Superiores Iztacala, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico
| | - Christopher Maulion
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Lavanya Bellumkonda
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - John Chang
- Section of General Internal Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Department of Medicine, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | | | | | - Javed Butler
- Baylor Scott and White Research Institute, Dallas, Texas
| | - Sean P. Collins
- Department of Emergency Medicine, Geriatric Research, Education and Clinical Center (GRECC), Vanderbilt University Medical Center and Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee
| | - Jeffrey M. Turner
- Division of Nephrology, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - F. Perry Wilson
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Clinical and Translational Research Accelerator, Yale University School of Medicine, New Haven, Connecticut
| | - Silvio E. Inzucchi
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Christopher S. Wilcox
- Division of Nephrology and Hypertension Center, Georgetown University, Washington, DC
| | - David H. Ellison
- Oregon Clinical and Translational Research Institute, Oregon Health and Science University, Portland, Oregon
| | - Jeffrey M. Testani
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
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Quarles CD, Macke M, Michalke B, Zischka H, Karst U, Sullivan P, Field MP. LC-ICP-MS method for the determination of "extractable copper" in serum. Metallomics 2021; 12:1348-1355. [PMID: 32789408 DOI: 10.1039/d0mt00132e] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Copper is an essential element for biological functions within humans and animals. There are several known diseases associated with Cu deficiency or overload, such as Menkes disease and Wilson disease, respectively. A common clinical method for determining extractable Cu levels in serum, which is thought to be potentially dangerous if in excess, is to subtract the value of tightly incorporated Cu in ceruloplasmin from total serum Cu. In this work, an automated sample preparation and liquid chromatography (LC) system was combined with inductively coupled plasma-mass spectrometry (ICP-MS) to determine bound Cu and extractable Cu in serum. This LC-ICP-MS method took 250 s for sample preparation and analysis, followed by a column recondition/system reset, thus, a 6 minute sample-to-sample time including sample preparation. The method was validated using serum collected from either control (Atp7b+/-) or Wilson disease rats (Atp7b-/-). The extractable Cu was found to be 4.0 ± 2.3 μM Cu in healthy control rats, but 2.1 ± 0.6 μM Cu in healthy Wilson rats, and 27 ± 16 μM Cu in diseased Wilson rats, respectively. In addition, the extractable Cu/bound Cu ratio was found to be 6.4 ± 3.5%, 38 ± 29%, and 34 ± 22%, respectively. These results suggest that the developed method could be of diagnostic value for Wilson disease, and possibly other copper related diseases.
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Affiliation(s)
- C Derrick Quarles
- Elemental Scientific, Inc., 7277 World Communications Dr., Omaha, NE, USA.
| | - Marcel Macke
- University of Münster, Institute of Inorganic and Analytical Chemistry, Corrensstrasse 30, 48149 Münster, Germany
| | - Bernhard Michalke
- Research Unit Analytical BioGeoChemistry, Helmholtz Center Munich, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
| | - Hans Zischka
- Institute of Molecular Toxicology and Pharmacology, Helmholtz Center Munich, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany and Technical University Munich, School of Medicine, Institute of Toxicology and Environmental Hygiene, Biedersteiner Strasse 29, 80802 Munich, Germany
| | - Uwe Karst
- University of Münster, Institute of Inorganic and Analytical Chemistry, Corrensstrasse 30, 48149 Münster, Germany
| | - Patrick Sullivan
- Elemental Scientific, Inc., 7277 World Communications Dr., Omaha, NE, USA.
| | - M Paul Field
- Elemental Scientific, Inc., 7277 World Communications Dr., Omaha, NE, USA.
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de la Vega E, Foster GL, Martínez-Botí MA, Anagnostou E, Field MP, Kim MH, Watson P, Wilson PA. Automation of boron chromatographic purification for δ 11 B analysis of coral aragonite. Rapid Commun Mass Spectrom 2020; 34:e8762. [PMID: 32067285 DOI: 10.1002/rcm.8762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 01/31/2020] [Accepted: 02/17/2020] [Indexed: 06/10/2023]
Abstract
RATIONALE To detect the small changes in past pH, the boron isotope ratio of coral carbonates, expressed as the δ11 B value, needs to be both precise and accurate (2sd <<1‰). Boron measurements by Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) require the boron to be carefully purified before analysis, which is time consuming, and requires specialist training. Here, we use the prepFAST-MC method that enables the automatic extraction of B (up to 25 ng load) from a CaCO3 matrix. METHODS Samples were purified using the prepFAST-MC automated system with a ~25-μL column of Amberlite IRA743 resin. Boron isotope measurements were performed by MC-ICPMS. The effects of matrix load, speed of sample loading onto the column, and blank contamination were tested to evaluate the effects on the purification process. The optimised protocol was tested on various standards and samples of aragonite corals. RESULTS The blank contribution for the approach is ~60 pg and is negligible given our sample size (<0.2% sample size). Efficiency of matrix removal is demonstrated with the addition of up to 1.6 mg of dissolved low-B calcium carbonate to NIST SRM 951 with no impact on the accuracy of δ11 B values. The Japanese Geological Survey Porites reference material JCp-1, boric acid standard NIST SRM 951, and seawater, all processed on the prepFAST-MC system, give δ11 B values within error of literature values (δ11 BJCp-1 = 24.31 ± 0.20‰ (2sd, n = 20); δ11 BNIST 951 = -0.02 ± 0.15‰ (2sd, n = 13) and δ11 BSeawater = 39.50 ± 0.06‰ (2sd, n = 2)). Results obtained from the coral Siderastrea siderea purified with the prepFAST-MC system show an average offset from the manual ion-exchange protocols of Δδ11 B = 0.01 ± 0.28‰ (2sd, n = 12). CONCLUSIONS Our study demonstrates the capacity of the prepFAST-MC method to generate accurate and reproducible δ11 B values for a range of materials, without fractionation, with efficient matrix removal and with negligible blank contribution.
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Affiliation(s)
- Elwyn de la Vega
- School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, SO14 3ZH, UK
| | - Gavin L Foster
- School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, SO14 3ZH, UK
| | - Miguel Angel Martínez-Botí
- School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, SO14 3ZH, UK
| | - Eleni Anagnostou
- School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, SO14 3ZH, UK
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstraße 1-3, 24148, Kiel, Germany
| | - M Paul Field
- Elemental Scientific, Inc, 7277 World Communications Drive, Omaha, NE, 68122, USA
| | - M Hwan Kim
- Elemental Scientific, Inc, 7277 World Communications Drive, Omaha, NE, 68122, USA
| | - Paul Watson
- Elemental Scientific, Inc, 7277 World Communications Drive, Omaha, NE, 68122, USA
| | - Paul A Wilson
- School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, SO14 3ZH, UK
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Metzger SC, Ticknor BW, Tevepaugh KN, Bostick DA, McBay EH, Field MP, Kim H, Hexel CR. Reproducible automated renewable column generation. SEP SCI TECHNOL 2020. [DOI: 10.1080/01496395.2019.1577439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Shalina C. Metzger
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Brian W. Ticknor
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Kayron N. Tevepaugh
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Debra A. Bostick
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Eddy H. McBay
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | | | - Hwan Kim
- Elemental Scientific Inc, Omaha, NE, USA
| | - Cole R. Hexel
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
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Shapses SA, Sukumar D, Schneider SH, Schlussel Y, Sherrell RM, Field MP, Ambia-Sobhan H. Vitamin D supplementation and calcium absorption during caloric restriction: a randomized double-blind trial. Am J Clin Nutr 2013; 97:637-45. [PMID: 23364004 PMCID: PMC3578405 DOI: 10.3945/ajcn.112.044909] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Weight loss (WL) is associated with a decrease in calcium absorption and may be one mechanism that induces bone loss with weight reduction. OBJECTIVE Because vitamin D supplementation has been shown to increase true fractional calcium absorption (TFCA), the goal of this study was to examine the effect of vitamin D during WL or weight maintenance (WM). DESIGN A randomized, placebo-controlled, double-blind 6-wk study was conducted in 82 postmenopausal women [BMI (in kg/m(2); ±SD): 30.2 ± 3.7] with 25-hydroxyvitamin D [25(OH)D] concentrations <70 nmol/L during either WL or WM. All women were given 10 μg vitamin D(3)/d and 1.2 g Ca/d and either weekly vitamin D(3) (375 μg) or a placebo equivalent to 63 μg (2500 IU)/d and 10 μg (400 IU)/d, respectively. We measured TFCA with the use of dual-stable isotopes, 25(OH)D, parathyroid hormone, estradiol, calcitriol, and urinary calcium at baseline and 6 wk in weight loss and vitamin D(3)-supplementation (WL-D; n = 19), weight maintenance and vitamin D(3)-supplementation (WM-D; n = 20), weight loss and placebo (n = 22), and weight maintenance and placebo (n = 21) groups. RESULTS WL groups lost 3.8 ± 1.1% of weight with no difference between vitamin D(3) supplementation and the placebo. The rise in serum 25(OH)D was greatest in the WL-D group (19.8 ± 14.5 nmol/L) compared with in WM-D (9.1 ± 10.3 nmol/L) and placebo groups (1.5 ± 10.9 nmol/L). TFCA increased with vitamin D(3) supplementation compared with placebo treatment (P < 0.01) and decreased during WL compared with WM. Serum 25(OH)D or 1,25-dihyroxyvitamin D did not correlate with TFCA. CONCLUSION These data show that vitamin D supplementation increases TFCA and that WL decreases TFCA and suggest that, when calcium intake is 1.2 g/d, either 10 or 63 μg vitamin D/d is sufficient to maintain the calcium balance. This trial was registered at clinicaltrials.gov as NCT00473031.
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Affiliation(s)
- Sue A Shapses
- Department of Nutritional Sciences and Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA.
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Rosenthal Y, Field MP, Sherrell RM. Precise determination of element/calcium ratios in calcareous samples using sector field inductively coupled plasma mass spectrometry. Anal Chem 2012; 71:3248-53. [PMID: 21662913 DOI: 10.1021/ac981410x] [Citation(s) in RCA: 230] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new method was developed for rapid and precise simultaneous determination of Mg/Ca, Sr/Ca, Mn/Ca, Cd/Ca, Ba/Ca and U/Ca ratios in foraminiferal shells using sector field inductively coupled plasma mass spectrometry (ICPMS). Element/calcium ratios were determined directly from intensity ratios using external, matrix-matched standard to correct for instrumental mass discrimination. Because of large differences in the abundance of chemical constituents of the foraminiferal shell, major elemental ratios were determined in analog mode (using (24)Mg, (43)Ca, (44)Ca, (55)Mn, and (88)Sr) whereas trace elemental ratios were determined in pulse-counting mode (using (111)Cd, (138)Ba, (238)U, and the low-abundance (46)Ca isotope). Matrix-induced variations in mass discrimination over a calcium concentration range of 2.0-24.5 mM were observed only for Mg/Ca and Cd/Ca ratios. However, these effects are negligible if the samples and standard calcium concentration are within a factor of 2-3. Multiratio method reproducibility was better than previously reported for other ICPMS methods yielding precision (1σ) of Sr/Ca = 0.45%; Mg/Ca = 0.45%, Mn/Ca = 0.8%, Cd/Ca = 1.7%, Ba/Ca = 0.7%, and U/Ca = 1.4% for foraminifera samples as small as 25 μg. Using this approach for a single-ratio analysis, Sr/Ca ratios were determined with precision of 0.06% (1σ) on carbonate samples as small as a single foraminifera shell (<10 μg). The new method is more sensitive, more precise, and simpler to use than previously available ICPMS techniques. It provides an efficient tool for simultaneous determination of several elemental ratios of paleoceanographic interest in a single foraminiferal sample, thereby reducing overall sample size requirement and analysis time.
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Affiliation(s)
- Y Rosenthal
- Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901-8521
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Shapses SA, Kendler DL, Robson R, Hansen KE, Sherrell RM, Field MP, Woolf E, Berd Y, Mantz AM, Santora AC. Effect of alendronate and vitamin D₃ on fractional calcium absorption in a double-blind, randomized, placebo-controlled trial in postmenopausal osteoporotic women. J Bone Miner Res 2011; 26:1836-44. [PMID: 21448918 DOI: 10.1002/jbmr.395] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Menopause and increasing age are associated with a decrease in calcium absorption that can contribute to the pathogenesis of osteoporosis. We hypothesized that alendronate plus vitamin D(3) (ALN + D) would increase fractional calcium absorption (FCA). In this randomized, double-blind, placebo-controlled multicenter clinical trial, 56 postmenopausal women with 25-hydroxyvitamin D [25(OH)D] concentrations of 25 ng/mL or less and low bone mineral density (BMD) received 5 weekly doses of placebo or alendronate 70 mg plus vitamin D(3) 2800 IU (ALN + D). Calcium intake was stabilized to approximately 1200 mg/d prior to randomization. FCA was determined using a dual-tracer stable-calcium isotope method. FCA and 25(OH)D were similar between treatment groups at baseline (0.31 ± 0.12 ng/mL and 19.8 ± 4.7 ng/mL, respectively). After 1 month of treatment, subjects randomized to ALN + D experienced a significant least squares (LS) mean [95% confidence interval (CI)] increase in FCA [0.070 (0.042, 0.098)], whereas FCA did not change significantly in the placebo group [-0.016 (-0.044, 0.012)]. After ALN + D treatment, patients had higher 25(OH)D levels (LS mean difference 7.3 ng/mL, p < .001). The rise in serum 1,25-dihydroxyvitamin D(3) (p < .02) and parathyroid hormone (p < .001) were greater in the ALN + D group than in placebo-treated patients. ALN + D was associated with an increase in FCA of 0.07. To our knowledge, there is no other trial showing such a marked rise in calcium absorption owing to treatment with a bisphosphonate or owing to a small rise in 25(OH)D. This unique response of ALN + D is important for the treatment of osteoporosis, but the exact mechanism requires further study.
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Affiliation(s)
- Sue A Shapses
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
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Murphy KR, Paul Field M, David Waite T, Ruiz GM. Trace elements in ships' ballast water as tracers of mid-ocean exchange. Sci Total Environ 2008; 393:11-26. [PMID: 18237765 DOI: 10.1016/j.scitotenv.2007.12.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Revised: 11/23/2007] [Accepted: 12/01/2007] [Indexed: 05/25/2023]
Abstract
Recent regulation mandates that ships conduct mid-ocean ballast water exchange (BWE) prior to discharging foreign ballast in U.S. territorial waters. We investigated the utility of dissolved concentration measurements for 6 elements (Ba, P, Mn, U, V and Mo) in the ballast tanks of ships operating in the North Pacific and Atlantic oceans as tracers of mid-ocean BWE. Relatively conservative elements Mo, U and V provided little additional information beyond that obtained from salinity, whereas nonconservative Ba, P and Mn offered greater resolution. The utility of Ba, P and Mn was further examined in the context of three criteria: (1) stability, or whether tracers maintain stable concentrations in ballast tanks over time; (2) fidelity, or the degree to which tracer concentrations in ballast tanks faithfully reflect concentrations at their ocean source; and (3) predictability, or the degree to which ballast tanks have a predictable and restricted range of tracer concentrations following BWE. We found that in water held in ballast tanks over time, average stability increased for Mn<P<Ba, as reflected by decreasing coefficients of variation (30%>21%>3%) and fidelity increased in the same direction. While Ba and P usually increased discrimination at high salinities, Mn was typically the most sensitive indicator of BWE and the presence of residual port water in partially exchanged tanks. Ba, P and Mn in tanks exchanged in the Atlantic exhibited different concentration ranges compared to tanks exchanged in the Pacific, suggesting that if trace elements are to be used to verify BWE, criteria for discriminating between exchanged and unexchanged ballast tanks may need to be basin-specific.
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Affiliation(s)
- Kathleen R Murphy
- Smithsonian Environmental Research Center, PO Box 28, Edgewater MD 21037, USA.
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Adgate JL, Mongin SJ, Pratt GC, Zhang J, Field MP, Ramachandran G, Sexton K. Relationships between personal, indoor, and outdoor exposures to trace elements in PM(2.5). Sci Total Environ 2007; 386:21-32. [PMID: 17692899 DOI: 10.1016/j.scitotenv.2007.07.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2007] [Revised: 06/06/2007] [Accepted: 07/03/2007] [Indexed: 05/16/2023]
Abstract
Twenty-four hour average fine particle concentrations of 23 trace elements (TEs) were measured concurrently in (a) ambient air in three urban neighborhoods (Battle Creek-BCK; East St. Paul-ESP; and Phillips-PHI), (b) air inside residences of participants, and (c) personal air near the breathing zone of healthy, non-smoking adults. The outdoor (O), indoor (I), and personal (P) samples were collected in the Minneapolis/St. Paul metropolitan area over three seasons (Spring, Summer, Fall) using either the federal reference (O) or inertial impactor (I,P) inlets to collect PM(2.5). In addition to descriptive statistics, a hierarchical, mixed-effects statistical model was used to estimate the mutually adjusted effects of monitor location, community, and season on mean differences between monitoring locations while accounting for within-subject and within-monitoring period correlation. The relationships among P, I, and O concentrations varied across TEs. The O concentrations were usually higher than P or I for elements like Ca and Al that originate mainly from entrained crustal material, while P concentrations were often highest for other elements with non-crustal sources. Unadjusted mixed model results demonstrated that O monitors more frequently underestimated than overestimated P TE exposures for elements associated with non-crustal sources. This finding was true even though the O TE measurements were taken in the same neighborhoods as the P and I measurements. Further adjustment for community or season effects in the mixed models reduced the number of significant O-P and O-I differences compared to unadjusted models, but still indicated a tendency for underestimation of personal and indoor TE exposures by central site monitors, particularly in the PHI community. These results indicate that community and season are important covariates for developing long term TE exposure estimates, and that personal exposure to trace elements in PM(2.5) is likely to be underestimated by outdoor central site monitors.
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Affiliation(s)
- John L Adgate
- Division of Environmental Health Sciences, School of Public Health, University of Minnesota, 420 Delaware St SE, MMC 807, Minneapolis, MN 55455, USA.
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Riedt CS, Schlussel Y, von Thun N, Ambia-Sobhan H, Stahl T, Field MP, Sherrell RM, Shapses SA. Premenopausal overweight women do not lose bone during moderate weight loss with adequate or higher calcium intake. Am J Clin Nutr 2007; 85:972-80. [PMID: 17413095 PMCID: PMC4008879 DOI: 10.1093/ajcn/85.4.972] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Weight loss is associated with bone loss, but this has not been examined in overweight premenopausal women. OBJECTIVE The aim of this study was to assess whether overweight premenopausal women lose bone with moderate weight loss at recommended or higher than recommended calcium intakes. DESIGN Overweight premenopausal women [n = 44; x (+/-SD) age: 38 +/- 6.4 y; body mass index (BMI): 27.7 +/- 2.1 kg/m(2)] were randomly assigned to either a normal (1 g/d) or high (1.8 g/d) calcium intake during 6 mo of energy restriction [weight loss (WL) groups] or were recruited for weight maintenance at 1 g Ca/d intake. Regional bone mineral density and content were measured by dual-energy X-ray absorptiometry, and markers of bone turnover were measured before and after weight loss. True fractional calcium absorption (TFCA) was measured at baseline and during caloric restriction by using a dual-stable calcium isotope method. RESULTS The WL groups lost 7.2 +/- 3.3% of initial body weight. No significant decrease in BMD or rise in bone turnover was observed with weight loss at normal or high calcium intake. The group that consumed high calcium showed a strong relation (r = 0.71) between increased femoral neck bone mineral density and increased serum 25-hydroxyvitamin D. No significant effect of weight loss on TFCA was observed, and the total calcium absorbed was adequate at 238 +/- 81 and 310 +/- 91 mg/d for the normal- and high-calcium WL groups, respectively. CONCLUSION Overweight premenopausal women do not lose bone during weight loss at the recommended calcium intake, which may be explained by sufficient amounts of absorbed calcium.
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Abstract
OBJECTIVE Roux-en-Y gastric bypass (RYGB) is considered to be the gold standard alternative treatment for severe obesity. Weight loss after RYGB results primarily from decreased food intake. Inadequate calcium (Ca) intake and metabolic bone disease can occur after gastric bypass. To our knowledge, whether malabsorption of Ca contributes to an altered Ca metabolism in the RYGB patient has not been addressed previously. RESEARCH METHODS AND PROCEDURES We recruited 25 extremely obese women in order to study true fractional Ca absorption (TFCA) before and 6 months after RYGB surgery, using a dual stable isotope method ((42)Ca and (43)Ca) and test load of Ca (200 mg). Hormones regulating Ca absorption and markers of bone turnover were also measured. RESULTS In 21 women (BMI 52.7 +/- 8.3 kg/m(2), age 43.9 +/- 10.4 years) who successfully completed the study, TFCA decreased from 0.36 +/- 0.08 to 0.24 +/- 0.09 (p < 0.001) after RYGB. Bone turnover markers increased significantly (p < 0.01). TFCA correlated with estradiol levels (r = 0.512, p < 0.02) and tended to correlate with 1,25 (OH)(2)D (r = 0.427, p < 0.06) at final measurement. Stepwise linear regression indicated that estradiol explained 62% of the variance for TFCA at 6 months post-surgery (p < 0.01). DISCUSSION TFCA decreases (0.12 +/- 0.08) after RYGB surgery but remains within normal range. Although only some patients were estimated to have low Ca absorption after surgery, all of the patients showed a dramatic increase in markers of bone resorption. The alteration in Ca metabolism after RYGB-induced weight loss appears to be regulated primarily by estradiol levels and might ultimately affect bone mass.
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Affiliation(s)
- Claudia S. Riedt
- Department of Nutritional Sciences, Rutgers University, New Jersey
| | | | - Robert M. Sherrell
- Institute of Marine and Coastal Sciences, Rutgers University, New Jersey
| | - M. Paul Field
- Institute of Marine and Coastal Sciences, Rutgers University, New Jersey
| | - Sue A. Shapses
- Department of Nutritional Sciences, Rutgers University, New Jersey
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Cifuentes M, Riedt CS, Brolin RE, Field MP, Sherrell RM, Shapses SA. Weight loss and calcium intake influence calcium absorption in overweight postmenopausal women. Am J Clin Nutr 2004; 80:123-30. [PMID: 15213038 PMCID: PMC4016237 DOI: 10.1093/ajcn/80.1.123] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Weight loss (WL) reduces bone mass and increases fracture risk. Mechanisms regulating calcium metabolism during WL are unclear. OBJECTIVE The objective was to assess the effect of 6 wk of WL at 2 different amounts of calcium intake [normal (NlCa): 1 g/d; high (HiCa): 1.8 g/d] on true fractional calcium absorption (TFCA), bone turnover, and bone-regulating hormones in overweight postmenopausal women. DESIGN Seventy-three women (body mass index, 26.9 +/- 1.9 kg/m(2)) were recruited either to consume a moderately energy-restricted diet (WL group) or to maintain their body weight [weight-maintenance (WM) group] and were randomly assigned to either the HiCa or the NlCa group in a double-blind manner. Subjects underwent weekly diet counseling, and measurements were taken at baseline and after 6 wk. RESULTS Fifty-seven women completed the study and had a baseline TFCA of 24.9 +/- 7.4%. Energy restriction significantly decreased the total calcium absorbed (P < 0.05) in the WL group (n = 32) compared with the WM group (n = 25; analysis of covariance). Regression analysis showed that a greater rate of weight loss suppressed TFCA and the total calcium absorbed (P < 0.05) in the HiCa group. The women in the NlCa WL group absorbed inadequate amounts of calcium (195 +/- 49 mg/d), whereas the women in the HiCa WL group absorbed adequate amounts (348 +/- 118 mg/d). Parathyroid hormone explained 22% of the variance in calcium absorbed in the NlCa group only. CONCLUSIONS We suggest that WL is associated with elevated calcium requirements that, if not met, could activate the calcium-parathyroid hormone axis to absorb more calcium. Normal intakes of calcium during energy restriction result in inadequate total calcium absorption and could ultimately compromise calcium balance and bone mass.
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Affiliation(s)
- Mariana Cifuentes
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ 08901, USA
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Field MP, Sherrell RM. Magnetic Sector ICPMS with Desolvating Micronebulization: Interference-Free Subpicogram Determination of Rare Earth Elements in Natural Samples. Anal Chem 1998; 70:4480-6. [DOI: 10.1021/ac980455v] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M. Paul Field
- Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901-8521
| | - Robert M. Sherrell
- Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901-8521
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