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Montana AV, Mildon A, Daniel AI, Pitino MA, Baxter JAB, Beggs MR, Unger SL, O'Connor DL, Walton K. Is Maternal Body Weight or Composition Associated with Onset of Lactogenesis II, Human Milk Production, or Infant Consumption of Mother's Own Milk? A Systematic Review and Meta-Analysis. Adv Nutr 2024:100228. [PMID: 38609047 DOI: 10.1016/j.advnut.2024.100228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 04/05/2024] [Accepted: 04/09/2024] [Indexed: 04/14/2024] Open
Abstract
Maternal adiposity impacts lactation performance, but the pathways are unclear. We conducted a systematic review to understand whether maternal adiposity (body mass index [BMI] or percentage fat mass) is associated with onset of lactogenesis II (copious milk; hours), human milk production (expressed volume/24 h), and infant consumption of mother's own milk (volume/24 h). We used random-effects standard meta-analyses to compare the relative risk (RR) of delayed lactogenesis II (>72 h) between mothers classified as underweight (BMI <18.5 kg/m2), healthy weight (BMI, 18.5-24.9 kg/m2), and overweight/obese (BMI >25 kg/m2) and random-effects meta-regressions to examine associations with hours to lactogenesis II and infant milk consumption. The certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation approach. We included 122 articles. Mothers with underweight (RR: 0.61; 95% CI: 0.46, 0.83; I2 = 46.27%; 8 articles/data points) or healthy weight status (RR: 0.72; 95% CI: 0.61, 0.84; I2 = 64.41%; 15 articles/data points) were less likely to experience delayed lactogenesis II than mothers with overweight/obesity. We found no association between maternal BMI and time onset of lactogenesis II (β: 1.45 h; 95% CI: -3.19, 6.09 h; P = 0.52, I2 = 0.00%; 8 articles, 15 data points). Due to limited data, we narratively reviewed articles examining BMI or percentage fat mass and milk production (n = 6); half reported an inverse association and half no association. We found no association between maternal BMI (β: 5.84 mL; 95% CI: -11.92, 23.60 mL; P = 0.51, I2 = 44.18%; 58 articles, 75 data points) or percentage fat mass (β: 6.54 mL; 95% CI: -3.60, 16.68 mL; P = 0.20, I2 = 21.40%; 30 articles, 32 data points) and infant milk consumption. The certainty of evidence for all outcomes was very low. In conclusion, mothers with overweight/obesity may be at risk of delayed lactogenesis II. The available data do not support an association with infant milk consumption, but the included studies do not adequately represent mothers with obesity. This study was registered in PROSPERO as 285344.
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Affiliation(s)
- Amanda V Montana
- Translational Medicine, The Hospital for Sick Children, Toronto ON, Canada; Department of Nutritional Sciences, University of Toronto, Toronto ON, Canada
| | - Alison Mildon
- Department of Nutritional Sciences, University of Toronto, Toronto ON, Canada
| | | | - Michael A Pitino
- Translational Medicine, The Hospital for Sick Children, Toronto ON, Canada; Department of Nutritional Sciences, University of Toronto, Toronto ON, Canada
| | - Jo-Anna B Baxter
- Department of Nutritional Sciences, University of Toronto, Toronto ON, Canada
| | - Megan R Beggs
- Translational Medicine, The Hospital for Sick Children, Toronto ON, Canada; Department of Nutritional Sciences, University of Toronto, Toronto ON, Canada
| | - Sharon L Unger
- Department of Nutritional Sciences, University of Toronto, Toronto ON, Canada; Paediatrics, Mount Sinai Hospital, Toronto ON, Canada; Division of Neonatology, The Hospital for Sick Children, Toronto ON, Canada
| | - Deborah L O'Connor
- Translational Medicine, The Hospital for Sick Children, Toronto ON, Canada; Department of Nutritional Sciences, University of Toronto, Toronto ON, Canada; Paediatrics, Mount Sinai Hospital, Toronto ON, Canada
| | - Kathryn Walton
- Translational Medicine, The Hospital for Sick Children, Toronto ON, Canada; Department of Family Relations & Applied Nutrition, University of Guelph, Guelph, ON, Canada.
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Beggs MR, Ashkin A, Larsen BMK, Garros D. Measuring Energy Requirements of Traumatic Brain Injury Patients in Pediatric Intensive Care With Indirect Calorimetry: A Comparison With Empiric Methods. Pediatr Crit Care Med 2023; 24:e468-e475. [PMID: 37125799 DOI: 10.1097/pcc.0000000000003266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
OBJECTIVES Energy requirements following moderate or severe pediatric traumatic brain injury (TBI) have not been fully elucidated. Indirect calorimetry (IC) is the gold standard for measuring resting energy expenditure (MREE) in PICU. However, technical complexity limits its use. We aimed to determine whether MREE differs from standard of care energy estimation and delivery in a cohort of pediatric patients following moderate to severe TBI during PICU admission. DESIGN Retrospective case series study. SETTING Single-center, 16-bed general PICU in Canada between May 2011 and January 2019. PATIENTS Children (0-18 yr) admitted to a PICU for moderate (Glasgow Coma Scale [GCS] 9-12) to severe TBI (GCS < 9) and had an IC study performed while mechanically ventilated. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS During the study period, 245 patients were admitted with the diagnosis of trauma with TBI. The study includes a convenience sample of 26 patients with severe ( n = 23) and moderate ( n = 3) TBI who underwent a total of 34 IC measurements. MREE varied considerably from 29% to 144% of predicted energy expenditure. Using Bland-Altman comparative analysis, neither Schofield nor World Health Organization predictive equations were in agreement with MREE. Only one measurement revealed that the patient was appropriately fed (energy provided in nutrition support was within 10% of MREE); 10 (38%) measurements revealed overfeeding and 15 (58%) underfeeding at the time of testing. CONCLUSIONS The present study adds to the small body of literature highlighting the limitations of predictive equations to evaluate energy requirements following moderate to severe pediatric TBI. IC, when feasible, should be used as the preferred method to orient PICU teams to feed such vulnerable patients.
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Affiliation(s)
- Megan R Beggs
- Nutrition Services, Alberta Health Services, Edmonton, AB, Canada
- Women and Children's Health Research Institute (WCHRI), University of Alberta, Edmonton, AB, Canada
| | - Allison Ashkin
- Nutrition Services, Alberta Health Services, Edmonton, AB, Canada
- Pediatric Intensive Care Unit, Stollery Children's Hospital, Edmonton, AB, Canada
| | - Bodil M K Larsen
- Nutrition Services, Alberta Health Services, Edmonton, AB, Canada
- Pediatric Intensive Care Unit, Stollery Children's Hospital, Edmonton, AB, Canada
- Department of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, AB, Canada
| | - Daniel Garros
- Pediatric Intensive Care Unit, Stollery Children's Hospital, Edmonton, AB, Canada
- Division of Critical Care, Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
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MacDonald T, Beggs MR, O'Neill D, Kozuka K, Dimke H, Alexander RT. Increased Slc34a2 expression and paracellular phosphate permeability contribute to high intestinal phosphate absorption in young mice. Acta Physiol (Oxf) 2023; 239:e14029. [PMID: 37563989 DOI: 10.1111/apha.14029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/12/2023]
Abstract
AIM Phosphorus is a critical constituent of bone as a component of hydroxyapatite. Bone mineral content accrues rapidly early in life necessitating a positive phosphorus balance, which could be established by a combination of increased renal reabsorption and intestinal absorption. Intestinal absorption can occur via a transcellular pathway mediated by the apical sodium-phosphate cotransporter, Slc34a2/NaPiIIb or via the paracellular pathway. We sought to determine how young mammals increase dietary phosphorus absorption from the small intestine to establish a positive phosphorus balance, a prerequisite for rapid bone growth. METHODS The developmental expression profile of genes mediating phosphate absorption from the small intestine was determined in mice by qPCR and immunohistochemistry. Additionally, Ussing chamber studies were performed on small bowel of young (p7-p14) and older (8- to 17-week-old) mice to examine developmental changes in paracellular Pi permeability and transcellular Pi transport. RESULTS Blood and urinary Pi levels were higher in young mice. Intestinal paracellular phosphate permeability of young mice was significantly increased relative to older mice across all intestinal segments. NaPiIIb expression was markedly increased in juvenile mice, in comparison to adult animals. Consistent with this, young mice had increased transcellular phosphate flux across the jejunum and ileum relative to older animals. Moreover, transcellular phosphate transport was attenuated by the NaPiIIb inhibitor NTX1942 in the jejunum and ileum of young mice. CONCLUSION Our results are consistent with young mice increasing phosphate absorption via increasing paracellular permeability and the NaPiIIb-mediated transcellular pathway.
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Affiliation(s)
- Tate MacDonald
- Department of Physiology, The University of Alberta, Edmonton, Alberta, Canada
- The Women and Children's Health Research Institute, Edmonton, Alberta, Canada
| | - Megan R Beggs
- Department of Physiology, The University of Alberta, Edmonton, Alberta, Canada
- The Women and Children's Health Research Institute, Edmonton, Alberta, Canada
| | - Debbie O'Neill
- Department of Physiology, The University of Alberta, Edmonton, Alberta, Canada
| | | | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
- Department of Nephrology, Odense University Hospital, Odense, Denmark
| | - R Todd Alexander
- Department of Physiology, The University of Alberta, Edmonton, Alberta, Canada
- The Women and Children's Health Research Institute, Edmonton, Alberta, Canada
- Department of Pediatrics, The University of Alberta, Edmonton, Alberta, Canada
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Beggs MR, Young K, Plain A, O'Neill DD, Raza A, Flockerzi V, Dimke H, Alexander RT. Maternal Epidermal Growth Factor Promotes Neonatal Claudin-2 Dependent Increases in Small Intestinal Calcium Permeability. Function (Oxf) 2023; 4:zqad033. [PMID: 37575484 PMCID: PMC10413934 DOI: 10.1093/function/zqad033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 06/01/2023] [Accepted: 06/12/2023] [Indexed: 08/15/2023] Open
Abstract
A higher concentration of calcium in breast milk than blood favors paracellular calcium absorption enabling growth during postnatal development. We aimed to determine whether suckling animals have greater intestinal calcium permeability to maximize absorption and to identify the underlying molecular mechanism. We examined intestinal claudin expression at different ages in mice and in human intestinal epithelial (Caco-2) cells in response to hormones or human milk. We also measured intestinal calcium permeability in wildtype, Cldn2 and Cldn12 KO mice and Caco-2 cells in response to hormones or human milk. Bone mineralization in mice was assessed by μCT. Calcium permeability across the jejunum and ileum of mice were 2-fold greater at 2 wk than 2 mo postnatal age. At 2 wk, Cldn2 and Cldn12 expression were greater, but only Cldn2 KO mice had decreased calcium permeability compared to wildtype. This translated to decreased bone volume, cross-sectional thickness, and tissue mineral density of femurs. Weaning from breast milk led to a 50% decrease in Cldn2 expression in the jejunum and ileum. Epidermal growth factor (EGF) in breast milk specifically increased only CLDN2 expression and calcium permeability in Caco-2 cells. These data support intestinal permeability to calcium, conferred by claudin-2, being greater in suckling mice and being driven by EGF in breast milk. Loss of the CLDN2 pathway leads to suboptimal bone mineralization at 2 wk of life. Overall, EGF-mediated control of intestinal claudin-2 expression contributes to maximal intestinal calcium absorption in suckling animals.
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Affiliation(s)
- Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
- The Women's & Children's Health Research Institute, Edmonton, AB T6G 1C9, Canada
| | - Kennedi Young
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Allen Plain
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Debbie D O'Neill
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ahsan Raza
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, 66421 Homburg, Germany
| | - Veit Flockerzi
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, 66421 Homburg, Germany
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense C DK-5000, Demark
- Department of Nephrology, Odense University Hospital, 5000 Odense C, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
- The Women's & Children's Health Research Institute, Edmonton, AB T6G 1C9, Canada
- Department of Pediatrics, University of Alberta, Edmonton, AB T6G 1C9, Canada
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Pitino MA, Beggs MR, O'Connor DL, Doyen A, Pouliot Y, Sergius-Ronot M, Unger S. Donor human milk processing and its impact on infant digestion: A systematic scoping review of in vitro and in vivo studies. Adv Nutr 2023; 14:173-189. [PMID: 36811588 PMCID: PMC10102984 DOI: 10.1016/j.advnut.2022.11.004] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 11/02/2022] [Accepted: 11/23/2022] [Indexed: 12/27/2022] Open
Abstract
When there is an inadequate supply of mother's milk, pasteurized donor human milk is preferred over formula to supplement feeds for preterm infants. Although providing donor milk helps to improve feeding tolerance and reduce necrotizing enterocolitis, changes to its composition and reductions in bioactivity during processing, are thought to contribute to the slower growth often exhibited by these infants. To improve the clinical outcomes of recipient infants by maximizing the quality of donor milk, research is currently investigating strategies to optimize all aspects of processing, including pooling, pasteurization, and freezing; however, reviews of this literature typically only summarize the impact of a processing technique on composition or bioactivity. Reviews of published research investigating the impact of donor milk processing on infant digestion/absorption are lacking and thus, was the objective for this systematic scoping review, Open Science Framework (https://doi.org/10.17605/OSF.IO/PJTMW). Databases were searched for primary research studies evaluating donor milk processing for pathogen inactivation or other rationale and subsequent effect on infant digestion/absorption. Non-human milk studies or those assessing other outcomes were excluded. Overall, 24 articles from 12,985 records screened were included. Most studied thermal methods to inactivate pathogens, predominantly Holder pasteurization (HoP) (62.5°C, 30 min) and high-temperature short-time. Heating consistently decreased lipolysis and increased proteolysis of lactoferrin and caseins; however, protein hydrolysis was unaffected from in vitro studies. The abundance and diversity of released peptides remain unclear and should be further explored. Greater investigation into less-harsh methods for pasteurization, such as high-pressure processing, is warranted. Only 1 study assessed the impact of this technique and found minimal impact on digestion outcomes compared with HoP. Fat homogenization appeared to positively impact fat digestion (n = 3 studies), and only 1 eligible study investigated freeze-thawing. Identified knowledge gaps regarding optimal methods of processing should be further explored to improve the quality and nutrition of donor milk.
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Affiliation(s)
- Michael A Pitino
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Megan R Beggs
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Deborah L O'Connor
- Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Department of Pediatrics, Sinai Health, Toronto, Ontario, Canada; Rogers Hixon Ontario Human Milk Bank, Sinai Health System, Toronto, Ontario, Canada
| | - Alain Doyen
- Université Laval, Département des Sciences des Aliments, Institut sur la nutrition et les aliments fonctionnels (INAF) Québec, Québec, Canada
| | - Yves Pouliot
- Université Laval, Département des Sciences des Aliments, Institut sur la nutrition et les aliments fonctionnels (INAF) Québec, Québec, Canada
| | - Mélanie Sergius-Ronot
- Université Laval, Département des Sciences des Aliments, Institut sur la nutrition et les aliments fonctionnels (INAF) Québec, Québec, Canada
| | - Sharon Unger
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Department of Pediatrics, Sinai Health, Toronto, Ontario, Canada; Rogers Hixon Ontario Human Milk Bank, Sinai Health System, Toronto, Ontario, Canada; Department of Pediatrics, Temerty Faculty of Medicine, University of Toronto, Ontario, Canada.
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Young K, Beggs MR, Grimbly C, Alexander RT. Regulation of 1 and 24 hydroxylation of vitamin D metabolites in the proximal tubule. Exp Biol Med (Maywood) 2022; 247:1103-1111. [PMID: 35482362 PMCID: PMC9335508 DOI: 10.1177/15353702221091982] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Calcium and phosphate are critical for numerous physiological processes. Consequently, the plasma concentration of these ions are tightly regulated. Calcitriol, the active form of vitamin D, is a positive modulator of mineralization as well as calcium and phosphate metabolism. The molecular and physiological effects of calcitriol are well documented. Calcitriol increases blood calcium and phosphate levels by increasing absorption from the intestine, and resorption of bone. Calcitriol synthesis is a multistep process. A precursor is first made via skin exposure to UV, it is then 25-hydroxylated in the liver to form 25-hydroxyitamin D. The next hydroxylation step occurs in the renal proximal tubule via the 1-αhydroxylase enzyme (encoded by CYP27B1) thereby generating 1,25-dihydroxyvitamin D, that is, calcitriol. At the same site, the 25-hydroxyvitamin D 24-hydroxlase enzyme encoded by CYP24A1 can hydroxylate 25-hydroxyvitamin D or calcitriol to deactivate the hormone. Plasma calcitriol levels are primarily determined by the regulated expression of CYP27B1 and CYP24A1. This occurs in response to parathyroid hormone (increases CYP27B1), calcitriol itself (decreases CYP27B1 and increases CYP24A1), calcitonin (increases or decreases CYP24A1 and increases CYP27B1), FGF23 (decreases CYP27B1 and increases CYP24A1) and potentially plasma calcium and phosphate levels themselves (mixed effects). Herein, we review the regulation of CYP27B1 and CYP24A1 transcription in response to the action of classic phophocalciotropic hormones and explore the possibility of direct regulation by plasma calcium.
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Affiliation(s)
- Kennedi Young
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada,Women and Children’s Health Institute, Edmonton, AB T6G 1C9, Canada
| | - Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada,Women and Children’s Health Institute, Edmonton, AB T6G 1C9, Canada
| | - Chelsey Grimbly
- Department of Paediatrics, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada,Women and Children’s Health Institute, Edmonton, AB T6G 1C9, Canada,Department of Paediatrics, University of Alberta, Edmonton, AB T6G 1C9, Canada,R Todd Alexander.
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Beggs MR, Bhullar H, Dimke H, Alexander RT. The contribution of regulated colonic calcium absorption to the maintenance of calcium homeostasis. J Steroid Biochem Mol Biol 2022; 220:106098. [PMID: 35339651 DOI: 10.1016/j.jsbmb.2022.106098] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/05/2022] [Accepted: 03/20/2022] [Indexed: 11/20/2022]
Abstract
Calcium absorption and secretion can occur along the length of the small and large intestine. To date, the focus of research into intestinal calcium absorption has been the small intestine, the site contributing the majority of intestinal calcium absorption. However, evidence that the colon contributes as much as 10% of enteral calcium transport has been available for decades. Transcellular calcium absorption and bidirectional paracellular calcium flux contributing to either net absorption or secretion have been observed in the colon, depending on the physiological state. Moreover, the calcium transport pathways contributing to colonic absorption or secretion are regulated by a variety of hormones, including calcitriol, plasma calcium and dietary factors, including prebiotics. Herein we review historical and recent research highlighting the role of colonic calcium transport in overall maintenance of calcium balance, and suggest these data are consistent with the colon being a site of significant regulated transepithelial calcium transport.
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Affiliation(s)
- Megan R Beggs
- Department of Physiology, University of Alberta, Canada; Women's and Children's Health Institute, Alberta, Canada
| | | | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Demark; Department of Nephrology, Odense University Hospital, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Canada; Women's and Children's Health Institute, Alberta, Canada; Department of Paediatrics, University of Alberta, Canada.
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Beggs MR, Bando N, Unger S, O'Connor DL. State of the evidence from clinical trials on human milk fortification for preterm infants. Acta Paediatr 2022; 111:1115-1120. [PMID: 35143058 DOI: 10.1111/apa.16283] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 02/08/2022] [Indexed: 12/22/2022]
Abstract
Infants born preterm or low birth weight are at risk for morbidity, mortality and later neuroimpairment. Appropriate early post-natal growth is associated with better outcomes in-hospital and post-discharge. Therefore, nutritional strategies that support growth may improve the long-term health of this population. Mother's milk with donor milk as a supplement are preferred sources of nutrition for these infants but may not always support growth, especially amongst infants born of very low birth weight (<1500 g) and or those with a major morbidity. Systematic reviews of randomised controlled trials to date demonstrate that multi-nutrient fortification of human milk improves in-hospital growth of preterm infants although data on long-term neurodevelopment are lacking. Further, individualised approaches to fortification based on milk analysis or the infant's metabolic response may improve growth over standard fortification. The evidence is insufficient to inform the timing of introducing fortifier, routine fortification of feeds post-discharge or routine use of fortifiers made from human instead of bovine milk. Importantly, there is insufficient data to determine if these fortification practices improve relevant clinical or neurodevelopmental outcomes. In sum, there is an urgent need for well-designed clinical trials to assess potential benefits and risks of fortification practices and at what cost.
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Affiliation(s)
- Megan R. Beggs
- Translational Medicine Program The Hospital for Sick Children Toronto Ontario Canada
| | - Nicole Bando
- Translational Medicine Program The Hospital for Sick Children Toronto Ontario Canada
- Department of Nutritional Sciences, Temerty Faculty of Medicine University of Toronto Toronto Ontario Canada
| | - Sharon Unger
- Department of Nutritional Sciences, Temerty Faculty of Medicine University of Toronto Toronto Ontario Canada
- Department of Pediatrics Sinai Health Toronto Ontario Canada
| | - Deborah L. O'Connor
- Translational Medicine Program The Hospital for Sick Children Toronto Ontario Canada
- Department of Nutritional Sciences, Temerty Faculty of Medicine University of Toronto Toronto Ontario Canada
- Department of Pediatrics Sinai Health Toronto Ontario Canada
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Megen WH, Beggs MR, An S, Ferreira PG, Lee JJ, Wolf MT, Alexander RT, Dimke H. Gentamicin induces calciuresis by blocking TRPV5. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r3385] [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] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Wouter H. Megen
- Department of Cardiovascular and Renal ResearchUniversity of Southern DenmarkOdense
| | - Megan R. Beggs
- PhysiologyUniversity of AlbertaAlbertaAB
- Women's and Children's Health InstituteAlbertaAB
| | - Sung‐Wan An
- PediatricsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Patrícia G. Ferreira
- Department of Cardiovascular and Renal ResearchUniversity of Southern DenmarkOdense
| | | | - Matthias T. Wolf
- PediatricsUniversity of Texas Southwestern Medical CenterDallasTX
| | - R. T. Alexander
- PhysiologyUniversity of AlbertaAlbertaAB
- Women's and Children's Health InstituteAlbertaAB
- PaediatricsUniversity of AlbertaAlbertaAB
- PhysiologyUniversity of AlbertaAlbertaAB
| | - Henrik Dimke
- Department of Cardiovascular and Renal ResearchUniversity of Southern DenmarkOdense
- NephrologyOdense University HospitalOdense
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van Megen WH, Beggs MR, An SW, Ferreira PG, Lee JJ, Wolf MT, Alexander RT, Dimke H. Gentamicin Inhibits Ca 2+ Channel TRPV5 and Induces Calciuresis Independent of the Calcium-Sensing Receptor-Claudin-14 Pathway. J Am Soc Nephrol 2022; 33:547-564. [PMID: 35022312 PMCID: PMC8975070 DOI: 10.1681/asn.2021030392] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 12/19/2021] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Treatment with the aminoglycoside antibiotic gentamicin can be associated with severe adverse effects, including renal Ca2+ wasting. The underlying mechanism is unknown but it has been proposed to involve activation of the Ca2+-sensing receptor (CaSR) in the thick ascending limb, which would increase expression of claudin-14 (CLDN14) and limit Ca2+ reabsorption. However, no direct evidence for this hypothesis has been presented. METHODS We studied the effect of gentamicin in vivo using mouse models with impaired Ca2+ reabsorption in the proximal tubule and the thick ascending limb. We used a Cldn14 promoter luciferase reporter assay to study CaSR activation and investigated the effect of gentamicin on activity of the distal nephron Ca2+ channel transient receptor potential vanilloid 5 (TRPV5), as determined by patch clamp in HEK293 cells. RESULTS Gentamicin increased urinary Ca2+ excretion in wild-type mice after acute and chronic administration. This calciuretic effect was unaltered in mice with genetic CaSR overactivation and was present in furosemide-treated animals, whereas the calciuretic effect in Cldn14-/- mice and mice with impaired proximal tubular Ca2+ reabsorption (claudin-2 [CLDN2]-deficient Cldn2-/- mice) was equivalent to that of wild-type mice. In vitro, gentamicin failed to activate the CaSR. In contrast, patch clamp analysis revealed that gentamicin strongly inhibited rabbit and human TRPV5 activity and chronic gentamicin administration downregulated distal nephron Ca2+ transporters. CONCLUSIONS Gentamicin does not cause hypercalciuria via activation of the CaSR-CLDN14 pathway or by interfering with proximal tubular CLDN2-dependent Ca2+ reabsorption. Instead, gentamicin blocks distal Ca2+ reabsorption by direct inhibition of the Ca2+ channel TRPV5. These findings offer new insights into Ca2+ wasting in patients treated with gentamicin.
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Affiliation(s)
- Wouter H. van Megen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Megan R. Beggs
- Department of Physiology, University of Alberta, Canada,Women and Children's Health Institute, Alberta, Canada
| | - Sung-Wan An
- Department of Pediatrics, Division of Pediatric Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Patrícia G. Ferreira
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Justin J. Lee
- Department of Physiology, University of Alberta, Canada
| | - Matthias T. Wolf
- Department of Pediatrics, Division of Pediatric Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - R. Todd Alexander
- Department of Physiology, University of Alberta, Canada,Women and Children's Health Institute, Alberta, Canada,Department of Pediatrics, University of Alberta, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark .,Department of Nephrology, Odense University Hospital, Denmark
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Lansing M, Slim G, Wizzard P, Rafii M, Pencharz PB, Nation PN, Beggs MR, Alexander RT, Wales PW, Turner JM, Ball RO. Intestinal resection affects whole-body arginine synthesis in neonatal piglets. Pediatr Res 2021; 89:1420-1426. [PMID: 32920606 DOI: 10.1038/s41390-020-01139-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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] [Received: 06/04/2020] [Revised: 08/01/2020] [Accepted: 08/06/2020] [Indexed: 11/09/2022]
Abstract
BACKGROUND Previous studies in piglets show a direct relationship between intestinal mass and arginine (Arg) synthesis. We aimed to study the effects of 75% intestinal resection on whole-body Arg synthesis. METHODS Piglets were allocated to sham or jejunocolic (JC) surgery and to enteral nutrition (EN) at 20% [sham (n = 8), JC (n = 10)], or 40% [sham (n = 4), JC (n = 5)]. A gastric tube was placed for EN and a venous catheter for parenteral nutrition and blood sampling. On day 6, a primed bolus and constant infusion of Arg m + 2 label and proline m + 1 label was delivered. In addition, 40% EN piglets received a citrulline (Cit) m + 3 tracer. Blood sampling was undertaken and whole-body Arg synthesis was calculated. On day 7, intestinal length was measured, and samples were collected for gene expression (PCR quantification) and histopathology. RESULTS On Day 7, sham piglets showed intestinal lengthening compared to JC (p = 0.02). Whole-body Arg synthesis was similar between groups (p = 0.50). Adjusting for absolute small intestinal length, JC piglets had greater Arg synthesis (p = 0.01). Expression of arginosuccinase was upregulated in the jejunum of JC compared to sham on 20% EN (p = 0.03). CONCLUSION This demonstrates for the first-time adaptive changes in intestinal Arg synthesis following intestinal resection. IMPACT The intestine makes a critical contribution to whole-body arginine synthesis, particularly in neonates, a human population at risk for short bowel syndrome. Therefore, we studied intestinal arginine synthesis in a neonatal piglet model of short bowel syndrome and demonstrated adaptive changes in the intestine that may preserve whole-body arginine synthesis, despite loss of intestinal mass. This research adds new information to our understanding of the effects a massive intestinal resection has on amino acid metabolism during neonatal development.
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Affiliation(s)
- Marihan Lansing
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - George Slim
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - Pamela Wizzard
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - Mahroukh Rafii
- Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Paul B Pencharz
- Departments of Pediatrics and Nutritional Sciences, University of Toronto, Toronto, ON, Canada
| | - Patrick N Nation
- Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada
| | - Megan R Beggs
- Department of Physiology at the University of Alberta, Edmonton, AB, Canada
| | - R Todd Alexander
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada.,Department of Physiology at the University of Alberta, Edmonton, AB, Canada
| | - Paul W Wales
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada.,Research Institute, The Hospital for Sick Children, Toronto, ON, Canada.,Division of General and Thoracic Surgery, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Justine M Turner
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada.
| | - Ron O Ball
- Department of Agricultural, Life & Environmental Sciences, University of Alberta, Edmonton, AB, Canada
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12
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Curry JN, Saurette M, Askari M, Pei L, Filla MB, Beggs MR, Rowe PS, Fields T, Sommer AJ, Tanikawa C, Kamatani Y, Evan AP, Totonchi M, Alexander RT, Matsuda K, Yu AS. Claudin-2 deficiency associates with hypercalciuria in mice and human kidney stone disease. J Clin Invest 2020; 130:1948-1960. [PMID: 32149733 PMCID: PMC7108907 DOI: 10.1172/jci127750] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [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] [Received: 02/01/2019] [Accepted: 01/08/2020] [Indexed: 12/29/2022] Open
Abstract
The major risk factor for kidney stone disease is idiopathic hypercalciuria. Recent evidence implicates a role for defective calcium reabsorption in the renal proximal tubule. We hypothesized that claudin-2, a paracellular cation channel protein, mediates proximal tubule calcium reabsorption. We found that claudin-2-null mice have hypercalciuria due to a primary defect in renal tubule calcium transport and papillary nephrocalcinosis that resembles the intratubular plugs in kidney stone formers. Our findings suggest that a proximal tubule defect in calcium reabsorption predisposes to papillary calcification, providing support for the vas washdown hypothesis. Claudin-2-null mice were also found to have increased net intestinal calcium absorption, but reduced paracellular calcium permeability in the colon, suggesting that this was due to reduced intestinal calcium secretion. Common genetic variants in the claudin-2 gene were associated with decreased tissue expression of claudin-2 and increased risk of kidney stones in 2 large population-based studies. Finally, we describe a family in which males with a rare missense variant in claudin-2 have marked hypercalciuria and kidney stone disease. Our findings indicate that claudin-2 is a key regulator of calcium excretion and a potential target for therapies to prevent kidney stones.
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Affiliation(s)
- Joshua N Curry
- Department of Molecular and Integrative Physiology and
- Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Matthew Saurette
- Department of Pediatrics and
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Masomeh Askari
- Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, Academic Center for Education, Culture and Research (ACECR), Tehran, Iran
| | - Lei Pei
- Division of Nephrology and Hypertension, Department of Internal Medicine, and
| | - Michael B Filla
- Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, USA
- Division of Nephrology and Hypertension, Department of Internal Medicine, and
| | - Megan R Beggs
- Department of Pediatrics and
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Peter Sn Rowe
- Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, USA
- Division of Nephrology and Hypertension, Department of Internal Medicine, and
| | - Timothy Fields
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Andre J Sommer
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio, USA
| | - Chizu Tanikawa
- Laboratory of Genome Technology, Human Genome Center, Institute of Medical Science, Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan
| | - Yoichiro Kamatani
- Laboratory for Statistical Analysis, RIKEN Center for Integrative Medical Sciences, Kanagawa, Japan
| | - Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Mehdi Totonchi
- Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, Academic Center for Education, Culture and Research (ACECR), Tehran, Iran
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - R Todd Alexander
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Koichi Matsuda
- Laboratory of Genome Technology, Human Genome Center, Institute of Medical Science, Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan
- Laboratory of Clinical Genome Sequencing, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan
| | - Alan Sl Yu
- Department of Molecular and Integrative Physiology and
- Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, USA
- Division of Nephrology and Hypertension, Department of Internal Medicine, and
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13
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Plain A, Pan W, O’Neill D, Ure M, Beggs MR, Farhan M, Dimke H, Cordat E, Alexander RT. Claudin-12 Knockout Mice Demonstrate Reduced Proximal Tubule Calcium Permeability. Int J Mol Sci 2020; 21:ijms21062074. [PMID: 32197346 PMCID: PMC7139911 DOI: 10.3390/ijms21062074] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/11/2020] [Accepted: 03/15/2020] [Indexed: 01/13/2023] Open
Abstract
The renal proximal tubule (PT) is responsible for the reabsorption of approximately 65% of filtered calcium, primarily via a paracellular pathway. However, which protein(s) contribute this paracellular calcium pore is not known. The claudin family of tight junction proteins confers permeability properties to an epithelium. Claudin-12 is expressed in the kidney and when overexpressed in cell culture contributes paracellular calcium permeability (PCa). We therefore examined claudin-12 renal localization and its contribution to tubular paracellular calcium permeability. Claudin-12 null mice (KO) were generated by replacing the single coding exon with β-galactosidase from Escherichia coli. X-gal staining revealed that claudin-12 promoter activity colocalized with aquaporin-1, consistent with the expression in the PT. PTs were microperfused ex vivo and PCa was measured. PCa in PTs from KO mice was significantly reduced compared with WT mice. However, urinary calcium excretion was not different between genotypes, including those on different calcium containing diets. To assess downstream compensation, we examined renal mRNA expression. Claudin-14 expression, a blocker of PCa in the thick ascending limb (TAL), was reduced in the kidney of KO animals. Thus, claudin-12 is expressed in the PT, where it confers paracellular calcium permeability. In the absence of claudin-12, reduced claudin-14 expression in the TAL may compensate for reduced PT calcium reabsorption.
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Affiliation(s)
- Allein Plain
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Wanling Pan
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Deborah O’Neill
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Megan Ure
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Megan R. Beggs
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
- The Women’s & Children’s Health Research Institute, 11405-87 Avenue, Edmonton, AB T6G 1C9 Canada;
| | - Maikel Farhan
- The Women’s & Children’s Health Research Institute, 11405-87 Avenue, Edmonton, AB T6G 1C9 Canada;
- Department of Pediatrics, The University of Alberta, Edmonton, AB T6J 2R7, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, 5230 Odense, Denmark;
- Department of Nephrology, Odense University Hospital, 5000 Odense, Denmark
| | - Emmanuelle Cordat
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - R. Todd Alexander
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
- The Women’s & Children’s Health Research Institute, 11405-87 Avenue, Edmonton, AB T6G 1C9 Canada;
- Department of Pediatrics, The University of Alberta, Edmonton, AB T6J 2R7, Canada
- Correspondence: ; Tel.: +1-(780)-248-5560
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14
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Beggs MR, Lee JJ, Busch K, Raza A, Dimke H, Weissgerber P, Engel J, Flockerzi V, Alexander RT. TRPV6 and Ca v1.3 Mediate Distal Small Intestine Calcium Absorption Before Weaning. Cell Mol Gastroenterol Hepatol 2019; 8:625-642. [PMID: 31398491 PMCID: PMC6889763 DOI: 10.1016/j.jcmgh.2019.07.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 07/15/2019] [Accepted: 07/17/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Intestinal Ca2+ absorption early in life is vital to achieving optimal bone mineralization. The molecular details of intestinal Ca2+ absorption have been defined in adults after peak bone mass is obtained, but they are largely unexplored during development. We sought to delineate the molecular details of transcellular Ca2+ absorption during this critical period. METHODS Expression of small intestinal and renal calcium transport genes was assessed by using quantitative polymerase chain reaction. Net calcium flux across small intestinal segments was measured in Ussing chambers, including after pharmacologic inhibition or genetic manipulation of TRPV6 or Cav1.3 calcium channels. Femurs were analyzed by using micro-computed tomography and histology. RESULTS Net TRPV6-mediated Ca2+ flux across the duodenum was absent in pre-weaned (P14) mice but present after weaning. In contrast, we found significant transcellular Ca2+ absorption in the jejunum at 2 weeks but not 2 months of age. Net jejunal Ca2+ absorption observed at P14 was not present in either Trpv6 mutant (D541A) mice or Cav1.3 knockout mice. We observed significant nifedipine-sensitive transcellular absorption across the ileum at P14 but not 2 months. Cav1.3 knockout pups exhibited delayed bone mineral accrual, compensatory nifedipine-insensitive Ca2+ absorption in the ileum, and increased expression of renal Ca2+ reabsorption mediators at P14. Moreover, weaning pups at 2 weeks reduced jejunal and ileal Cav1.3 expression. CONCLUSIONS We have detailed novel pathways contributing to transcellular Ca2+ transport across the distal small intestine of mice during development, highlighting the complexity of the multiple mechanisms involved in achieving a positive Ca2+ balance early in life.
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Affiliation(s)
- Megan R. Beggs
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada,The Women’s & Children’s Health Research Institute, Edmonton, Alberta, Canada
| | - Justin J. Lee
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada,The Women’s & Children’s Health Research Institute, Edmonton, Alberta, Canada
| | - Kai Busch
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Homburg, Germany
| | - Ahsan Raza
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Homburg, Germany
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Petra Weissgerber
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Homburg, Germany
| | - Jutta Engel
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, School of Medicine, Homburg, Germany
| | - Veit Flockerzi
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Homburg, Germany
| | - R. Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada,The Women’s & Children’s Health Research Institute, Edmonton, Alberta, Canada,Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada,Correspondence Address correspondence to: R. Todd Alexander, MD, PhD, Department of Pediatrics, 4-585 Edmonton Clinic Health Academy, 11405 – 87 Avenue, University of Alberta, Edmonton, Alberta T6G 2R7, Canada. fax: (780) 248-5556.
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15
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Lee JJ, Liu X, O'Neill D, Beggs MR, Weissgerber P, Flockerzi V, Chen XZ, Dimke H, Alexander RT. Activation of the calcium sensing receptor attenuates TRPV6-dependent intestinal calcium absorption. JCI Insight 2019; 5:128013. [PMID: 31013259 DOI: 10.1172/jci.insight.128013] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Plasma calcium (Ca2+) is maintained by amending the release of parathyroid hormone and through direct effects of the Ca2+ sensing receptor (CaSR) in the renal tubule. Combined, these mechanisms alter intestinal Ca2+ absorption by modulating 1,25-dihydroxy vitamin D3 production, bone resorption, and renal Ca2+ excretion. The CaSR is a therapeutic target in the treatment of secondary hyperparathyroidism and hypocalcemia a common complication of calcimimetic therapy. The CaSR is also expressed in intestinal epithelium, however, a direct role in regulating local intestinal Ca2+ absorption is unknown. Chronic CaSR activation decreased expression of genes involved in Ca2+ absorption. In Ussing chambers, increasing extracellular Ca2+ or basolateral application of the calcimimetic cinacalcet decreased net Ca2+ absorption across intestinal preparations acutely. Conversely, Ca2+ absorption increased with decreasing extracellular Ca2+ concentration. These responses were absent in mice expressing a non-functional TRPV6, TRPV6D541A. Cinacalcet also attenuated Ca2+ fluxes through TRPV6 in Xenopus oocytes when co-expressed with the CaSR. Moreover, the phospholipase C inhibitor, U73122, prevented cinacalcet-mediated inhibition of Ca2+ flux. These results reveal a regulatory pathway whereby activation of the CaSR in the basolateral membrane of the intestine directly attenuates local Ca2+ absorption via TRPV6 to prevent hypercalcemia and help explain how calcimimetics induce hypocalcemia.
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Affiliation(s)
- Justin J Lee
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.,The Women's and Children's Health Research Institute, Edmonton, Alberta, Canada
| | - Xiong Liu
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Debbie O'Neill
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.,The Women's and Children's Health Research Institute, Edmonton, Alberta, Canada
| | - Petra Weissgerber
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Hamburg, Germany
| | - Veit Flockerzi
- Experimentelle und Klinische Pharmakologie und Toxikologie, Saarland University, Hamburg, Germany
| | - Xing-Zhen Chen
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.,Department of Nephrology, Odense University Hospital, Odense, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.,The Women's and Children's Health Research Institute, Edmonton, Alberta, Canada.,Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
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16
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Beggs MR, Plain A, Lee JJ, Alexander RT. Claudin‐2 Confers Calcium Permeability to the Jejunum and Ileum in Early Life. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.575.16] [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] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Allen Plain
- PhysiologyUniversity of AlbertaEdmontonABCanada
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17
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Lian J, Watts R, Quiroga AD, Beggs MR, Alexander RT, Lehner R. Ces1d deficiency protects against high-sucrose diet-induced hepatic triacylglycerol accumulation. J Lipid Res 2019; 60:880-891. [PMID: 30737251 PMCID: PMC6446703 DOI: 10.1194/jlr.m092544] [Citation(s) in RCA: 14] [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] [Received: 01/16/2019] [Indexed: 12/20/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Triacylglycerol accumulation in the liver is a hallmark of NAFLD. Metabolic studies have confirmed that increased hepatic de novo lipogenesis (DNL) in humans contributes to fat accumulation in the liver and to NAFLD progression. Mice deficient in carboxylesterase (Ces)1d expression are protected from high-fat diet-induced hepatic steatosis. To investigate whether loss of Ces1d can also mitigate steatosis induced by over-activated DNL, WT and Ces1d-deficient mice were fed a lipogenic high-sucrose diet (HSD). We found that Ces1d-deficient mice were protected from HSD-induced hepatic lipid accumulation. Mechanistically, Ces1d deficiency leads to activation of AMP-activated protein kinase and inhibitory phosphorylation of acetyl-CoA carboxylase. Together with our previous demonstration that Ces1d deficiency attenuated high-fat diet-induced steatosis, this study suggests that inhibition of CES1 (the human ortholog of Ces1d) might represent a novel pharmacological target for prevention and treatment of NAFLD.
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Affiliation(s)
- Jihong Lian
- Group on Molecular and Cell Biology of Lipids University of Alberta, Alberta, Canada; Departments of Pediatrics, University of Alberta, Alberta, Canada
| | - Russell Watts
- Group on Molecular and Cell Biology of Lipids University of Alberta, Alberta, Canada; Departments of Pediatrics, University of Alberta, Alberta, Canada
| | - Ariel D Quiroga
- Instituto de Fisiología Experimental (IFISE), Área Morfología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, UNR, Rosario, Argentina
| | | | - R Todd Alexander
- Departments of Pediatrics, University of Alberta, Alberta, Canada; Physiology, University of Alberta, Alberta, Canada
| | - Richard Lehner
- Group on Molecular and Cell Biology of Lipids University of Alberta, Alberta, Canada; Departments of Pediatrics, University of Alberta, Alberta, Canada; Cell Biology, University of Alberta, Alberta, Canada.
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18
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Lee J, Liu X, O'Neill D, Beggs MR, Weissgerber P, Flockerzi V, Chen X, Dimke H, Alexander T. Basolateral Calcium Sensing Receptor Mediated Regulation of TRPV6‐dependent Transcellular Calcium Absorption. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.575.17] [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] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Justin Lee
- PhysiologyUniversity of AlbertaEdmontonABCanada
- Women and Children's Health Research InstituteEdmontonABCanada
| | - Xiong Liu
- PhysiologyUniversity of AlbertaEdmontonABCanada
| | | | - Megan R Beggs
- PhysiologyUniversity of AlbertaEdmontonABCanada
- Women and Children's Health Research InstituteEdmontonABCanada
| | | | | | | | - Henrik Dimke
- Department of Cardiovascular and Renal ResearchUniversity of Southern DenmarkOdenseDenmark
| | - Todd Alexander
- PhysiologyUniversity of AlbertaEdmontonABCanada
- PaediatricsUniversity of AlbertaEdmontonABCanada
- Women and Children's Health Research InstituteEdmontonABCanada
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19
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Larsen BMK, Beggs MR, Leong AY, Kang SH, Persad R, Garcia Guerra G. Can energy intake alter clinical and hospital outcomes in PICU? Clin Nutr ESPEN 2018; 24:41-46. [PMID: 29576361 DOI: 10.1016/j.clnesp.2018.02.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 02/08/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Energy is essential for the treatment and recovery of children admitted to Pediatric Intensive Care Units (PICU). There are significant immediate and long-term health consequences of both under- and over-feeding in this population. Energy requirements of critically ill children vary depending on age, nutritional status, sepsis, fever, pharmacotherapy, and duration and stage of critical illness. This study aimed to determine the incidence of over- and under-feeding and to compare hospital outcomes between these feeding categories. Secondary outcomes were collected to describe the association between feeding categories and biochemistries (serum lactate, triglycerides, C-reactive protein). METHODS An ethics approved retrospective study of children admitted to PICU was performed. All intubated patients admitted to PICU (2008-2013) were included, except those in which an IC test was not feasible. Data collection included demographics, the primary outcome variable reported as under feeding (<90%MREE), appropriate (MREE ±10%) or overfeeding (>110% MREE) determined through comparison of measured resting energy expenditure (MREE) using indirect calorimetry (IC) to actual energy intake based on predicted basal metabolic rate (PBMR) and clinical outcomes mechanical ventilation and PICU length of stay (LOS). Data were analysed with descriptive methods, ANOVA and linear regression models. RESULTS A total of 139 patients aged 10 (range 0.03-204) months were included. Sixty (43%) were female and 77 (55%) were admitted after a surgical procedure. A total of 210 IC tests were conducted showing a statistically significant difference between MREE measurements and PBMR (p = 0.019). Of the 210 measurements, only 26 measures (12.4%) demonstrated appropriate feeding, while 72 (34.3) were underfed and 112 (53.3%) were overfed. Children who were overfed had significantly longer PICU LOS (median 45.5, IQR 47.8 days) compared to those children in the appropriately fed (median 21.0, IQR 54.5 days), and underfed groups (median 16.5, IQR 21.3 days). There was a mean difference between the over and under feeding category and ventilation days after adjusting for age and PRISM score (p = 0.026), suggesting decreased mechanical ventilation days for underfed. Children who were underfed had significantly higher CRP (median 75.5, IQR 152.8 mg/L) compared to those children in the appropriately fed (median 57.8, IQR 90.9 mg/L) and overfed groups (median 22.4, IQR 56.2 mg/L). CONCLUSIONS This retrospective study confirms that estimations of energy expenditure in critically ill children are inaccurate leading to unintended under and overfeeding. Importantly under feeding seems to be associated with fewer mechanical ventilation days and PICU LOS. Further research is required to elucidate the role of optimal nutrition in altering clinical variables in this population.
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Affiliation(s)
- Bodil M K Larsen
- Nutrition Services, Alberta Health Services, Edmonton, Alberta, Canada; Department of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, Alberta, Canada; Women and Children's Health Research Institute (WCHRI), University of Alberta, Edmonton, Alberta, Canada; Department of Pediatrics, University of Alberta, Stollery Children's Hospital, Edmonton, Alberta, Canada.
| | - Megan R Beggs
- Nutrition Services, Alberta Health Services, Edmonton, Alberta, Canada; Women and Children's Health Research Institute (WCHRI), University of Alberta, Edmonton, Alberta, Canada
| | - Amanda Y Leong
- Department of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Sung Hyun Kang
- Women and Children's Health Research Institute (WCHRI), University of Alberta, Edmonton, Alberta, Canada
| | - Rabin Persad
- Department of Pediatrics, University of Alberta, Stollery Children's Hospital, Edmonton, Alberta, Canada
| | - Gonzalo Garcia Guerra
- Department of Pediatrics, University of Alberta, Stollery Children's Hospital, Edmonton, Alberta, Canada
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20
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Krishnan D, Pan W, Beggs MR, Trepiccione F, Chambrey R, Eladari D, Cordat E, Dimke H, Alexander RT. Deficiency of Carbonic Anhydrase II Results in a Urinary Concentrating Defect. Front Physiol 2018; 8:1108. [PMID: 29354070 PMCID: PMC5760551 DOI: 10.3389/fphys.2017.01108] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 12/14/2017] [Indexed: 01/23/2023] Open
Abstract
Carbonic anhydrase II (CAII) is expressed along the nephron where it interacts with a number of transport proteins augmenting their activity. Aquaporin-1 (AQP1) interacts with CAII to increase water flux through the water channel. Both CAII and aquaporin-1 are expressed in the thin descending limb (TDL); however, the physiological role of a CAII-AQP1 interaction in this nephron segment is not known. To determine if CAII was required for urinary concentration, we studied water handling in CAII-deficient mice. CAII-deficient mice demonstrate polyuria and polydipsia as well as an alkaline urine and bicarbonaturia, consistent with a type III renal tubular acidosis. Natriuresis and hypercalciuria cause polyuria, however, CAII-deficient mice did not have increased urinary sodium nor calcium excretion. Further examination revealed dilute urine in the CAII-deficient mice. Urinary concentration remained reduced in CAII-deficient mice relative to wild-type animals even after water deprivation. The renal expression and localization by light microscopy of NKCC2 and aquaporin-2 was not altered. However, CAII-deficient mice had increased renal AQP1 expression. CAII associates with and increases water flux through aquaporin-1. Water flux through aquaporin-1 in the TDL of the loop of Henle is essential to the concentration of urine, as this is required to generate a concentrated medullary interstitium. We therefore measured cortical and medullary interstitial concentration in wild-type and CAII-deficient mice. Mice lacking CAII had equivalent cortical interstitial osmolarity to wild-type mice: however, they had reduced medullary interstitial osmolarity. We propose therefore that reduced water flux through aquaporin-1 in the TDL in the absence of CAII prevents the generation of a maximally concentrated medullary interstitium. This, in turn, limits urinary concentration in CAII deficient mice.
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Affiliation(s)
- Devishree Krishnan
- Department of Physiology, University of Alberta, Edmonton, AB, Canada.,The Women's and Children's Health Research Institute, Edmonton, AB, Canada
| | - Wanling Pan
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, AB, Canada.,The Women's and Children's Health Research Institute, Edmonton, AB, Canada
| | - Francesco Trepiccione
- Department of Cardio-Thoracic and Respiratory Science, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Régine Chambrey
- Institut National de la Santé et de la Recherche Médicale Diabète athérothrombose Thérapies Réunion Océan Indien (DéTROI) Université de La Réunion, CYROI, La Réunion, France.,Centre National de la Recherche Scientifique, Délégation Paris Michel-Ange, Sainte-Clotilde, France
| | - Dominique Eladari
- Institut National de la Santé et de la Recherche Médicale Diabète athérothrombose Thérapies Réunion Océan Indien (DéTROI) Université de La Réunion, CYROI, La Réunion, France.,Service d'Explorations Fonctionnelles Rénales, Hôpital Felix Guyon, Centre Hospitalier Universitaire de la Réunion, La Réunion, France
| | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, AB, Canada.,The Women's and Children's Health Research Institute, Edmonton, AB, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB, Canada.,The Women's and Children's Health Research Institute, Edmonton, AB, Canada.,Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
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Abstract
Calcium and phosphate are critical for a myriad of physiological and cellular processes within the organism. Consequently, plasma levels of calcium and phosphate are tightly regulated. This occurs through the combined effects of the phospho- and calciotropic hormones, parathyroid hormone (PTH), active vitamin D
3, and fibroblast growth factor 23 (FGF23). The organs central to this are the kidneys, intestine, and bone. In the kidney, the proximal tubule reabsorbs the majority of filtered calcium and phosphate, which amounts to more than 60% and 90%, respectively. The basic molecular mechanisms responsible for phosphate reclamation are well described, and emerging work is delineating the molecular identity of the paracellular shunt wherein calcium permeates the proximal tubular epithelium. Significant experimental work has delineated the molecular effects of PTH and FGF23 on these processes as well as their regulation of active vitamin D
3 synthesis in this nephron segment. The integrative effects of both phospho- and calciotropic hormones on proximal tubular solute transport and subsequently whole body calcium-phosphate balance thus have been further complicated. Here, we first review the molecular mechanisms of calcium and phosphate reabsorption from the proximal tubule and how they are influenced by the phospho- and calciotropic hormones acting on this segment and then consider the implications on both renal calcium and phosphate handling as well as whole body mineral balance.
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Affiliation(s)
- Justin J Lee
- Department of Physiology, University of Alberta, Edmonton, Canada.,The Women and Children's Health Research Institute, Edmonton, Canada
| | - Allein Plain
- Department of Physiology, University of Alberta, Edmonton, Canada.,The Women and Children's Health Research Institute, Edmonton, Canada
| | - Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, Canada.,The Women and Children's Health Research Institute, Edmonton, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, Canada.,The Women and Children's Health Research Institute, Edmonton, Canada.,Department of Pediatrics, Edmonton Clinic Health Academy, University of Alberta, Edmonton, Canada
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22
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Beggs MR, Appel I, Svenningsen P, Skjødt K, Alexander RT, Dimke H. Expression of transcellular and paracellular calcium and magnesium transport proteins in renal and intestinal epithelia during lactation. Am J Physiol Renal Physiol 2017; 313:F629-F640. [DOI: 10.1152/ajprenal.00680.2016] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 05/01/2017] [Accepted: 05/17/2017] [Indexed: 01/25/2023] Open
Abstract
Significant alterations in maternal calcium (Ca2+) and magnesium (Mg2+) balance occur during lactation. Ca2+ is the primary divalent cation mobilized into breast milk by demineralization of the skeleton and alterations in intestinal and renal Ca2+ transport. Mg2+ is also concentrated in breast milk, but the underlying mechanisms are not well understood. To determine the molecular alterations in Ca2+ and Mg2+ transport in the intestine and kidney during lactation, three groups of female mice consisting of either nonpregnant controls, lactating mice, or mice undergoing involution were examined. The fractional excretion of Ca2+, but not Mg2+, rose significantly during lactation. Renal 1-α hydroxylase and 24-OHase mRNA levels increased markedly, as did plasma 1,25 dihydroxyvitamin D levels. This was accompanied by significant increases in intestinal expression of Trpv6 and S100g in lactating mice. However, no alterations in the expression of cation-permeable claudin-2, claudin-12, or claudins-15 were found in the intestine. In the kidney, increased expression of Trpv5 and Calb1 was observed during lactation, while no changes in claudins involved in Ca2+ and Mg2+ transport (claudin-2, claudin-14, claudin-16, or claudin-19) were found. Consistent with the mRNA expression, expression of both calbindin-D28K and transient receptor potential vanilloid 5 (TRPV5) proteins increased. Colonic Trpm6 expression increased during lactation, while renal Trpm6 remained unaltered. In conclusion, proteins involved in transcellular Ca2+ and Mg2+ transport pathways increase during lactation, while expression of paracellular transport proteins remained unchanged. Increased fractional Ca2+ excretion can be explained by vitamin D-dependent intestinal hyperabsorption and bone demineralization, despite enhanced transcellular Ca2+ uptake by the kidney.
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Affiliation(s)
- Megan R. Beggs
- Membrane Protein Disease Research Group, Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Ida Appel
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Per Svenningsen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Karsten Skjødt
- Department of Cancer and Inflammation, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark; and
| | - R. Todd Alexander
- Membrane Protein Disease Research Group, Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
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23
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Abstract
Calcium is vital for many physiological functions including bone mineralization. Postnatal deposition of calcium into bone is greatest in infancy and continues through childhood and adolescence until peek mineral density is reached in early adulthood. Thereafter, bone mineral density remains static until it eventually declines in later life. A positive calcium balance, i.e. more calcium absorbed than excreted, is crucial to bone deposition during growth and thus to peek bone mineral density. Dietary calcium is absorbed from the intestine into the blood. It is then filtered by the renal glomerulus and either reabsorbed by the tubule or excreted in the urine. Calcium can be (re)absorbed across intestinal and renal epithelia via both transcellular and paracellular pathways. Current evidence suggests that significant intestinal and renal calcium transport changes occur throughout development. However, the molecular details of these alterations are incompletely delineated. Here we first briefly review the current model of calcium transport in the intestine and renal tubule in the adult. Then, we describe what is known with regard to calcium handling through postnatal development, and how alterations may aid in mediating a positive calcium balance. The role of transcellular and paracellular calcium transport pathways and the contribution of specific intestinal and tubular segments vary with age. However, the current literature highlights knowledge gaps in how specifically intestinal and renal calcium (re)absorption occurs early in postnatal development. Future research should clarify the specific changes in calcium transport throughout early postnatal development including mediators of these alterations enabling appropriate bone mineralization. Impact statement This mini review outlines the current state of knowledge pertaining to the molecules and mechanisms maintaining a positive calcium balance throughout postnatal development. This process is essential to achieving optimal bone mineral density in early adulthood, thereby lowering the lifetime risk of osteoporosis.
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Affiliation(s)
- Megan R Beggs
- 1 Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2R7, Canada
| | - R Todd Alexander
- 1 Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2R7, Canada.,2 Department of Pediatrics, University of Alberta, Edmonton, Alberta T6G 2R7, Canada
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24
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Alexander RT, Beggs MR, Zamani R, Marcussen N, Frische S, Dimke H. Ultrastructural and immunohistochemical localization of plasma membrane Ca2+-ATPase 4 in Ca2+-transporting epithelia. Am J Physiol Renal Physiol 2015; 309:F604-16. [PMID: 26180241 DOI: 10.1152/ajprenal.00651.2014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 07/11/2015] [Indexed: 01/07/2023] Open
Abstract
Plasma membrane Ca(2+)-ATPases (PMCAs) participate in epithelial Ca(2+) transport and intracellular Ca(2+) signaling. The Pmca4 isoform is enriched in distal nephron isolates and decreased in mice lacking the epithelial transient receptor potential vanilloid 5 Ca(2+) channel. We therefore hypothesized that Pmca4 plays a significant role in transcellular Ca(2+) flux and investigated the localization and regulation of Pmca4 in Ca(2+)-transporting epithelia. Using antibodies directed specifically against Pmca4, we found it expressed only in the smooth muscle layer of mouse and human intestines, whereas pan-specific Pmca antibodies detected Pmca1 in lateral membranes of enterocytes. In the kidney, Pmca4 showed broad localization to the distal nephron. In the mouse, expression was most abundant in segments coexpressing the epithelial ransient receptor potential vanilloid 5 Ca(2+) channel. Significant, albeit lower, expression was also evident in the region encompassing the cortical thick ascending limbs, macula densa, and early distal tubules as well as smooth muscle layers surrounding renal vessels. In the human kidney, a similar pattern of distribution was observed, with the highest PMCA4 expression in Na(+)-Cl(-) cotransporter-positive tubules. Electron microscopy demonstrated Pmca4 localization in distal nephron cells at both the basolateral membrane and intracellular perinuclear compartments but not submembranous vesicles, suggesting rapid trafficking to the plasma membrane is unlikely to occur in vivo. Pmca4 expression was not altered by perturbations in Ca(2+) balance, pointing to a housekeeping function of the pump in Ca(2+)-transporting epithelia. In conclusion, Pmca4 shows a divergent expression pattern in Ca(2+)-transporting epithelia, inferring diverse roles for this isoform not limited to transepithelial Ca(2+) transport.
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Affiliation(s)
- R Todd Alexander
- Department of Pediatrics, The University of Alberta, Edmonton, Alberta, Canada; Membrane Protein Disease Research Group, The University of Alberta, Edmonton, Alberta, Canada
| | - Megan R Beggs
- Membrane Protein Disease Research Group, The University of Alberta, Edmonton, Alberta, Canada
| | - Reza Zamani
- Department of Urology, Odense University Hospital, Odense, Denmark
| | - Niels Marcussen
- Department of Clinical Pathology, Odense University Hospital, Odense, Denmark
| | - Sebastian Frische
- Department of Biomedicine, University of Aarhus, Aarhus, Denmark; and
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Demark
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