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Ahlborn NG, Montoya CA, Roy NC, Ye A, Samuelsson LM, Wieliczko RJ, McNabb WC. Heat Treatment and Homogenization Influence the Gastric Digestion of Bovine Milk Protein in Growing Pigs as an Adult Human Model. J Nutr 2024:S0022-3166(24)00238-4. [PMID: 38703889 DOI: 10.1016/j.tjnut.2024.04.035] [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: 02/08/2024] [Revised: 03/26/2024] [Accepted: 04/26/2024] [Indexed: 05/06/2024] Open
Abstract
BACKGROUND Bovine milk processing influences the structure of the curd formed during gastric digestion, which may alter gastric protein hydrolysis and impact amino acid (AA) release into the small intestine. OBJECTIVES This study aimed to determine the influence of heat treatment and homogenization on the gastric protein digestion and AA emptying of bovine milk. METHODS Nine-wk-old pigs (n = 144) consumed either raw, pasteurized nonhomogenized (PNH), pasteurized homogenized (PH), or ultra-high-temperature homogenized (UHT) bovine milk for 10 d. On day 11, fasted pigs received the milk treatment (500 mL) before gastric contents were collected at 0, 20, 60, 120, 180, and 300 min postprandially. The apparent degree of gastric protein hydrolysis (based on the release of free amino groups), apparent gastric disappearance of individual proteins [based on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gel band intensity], and the gastric emptying of digested protein and AA were determined. RESULTS During the first 60 min, the rate of apparent gastric protein hydrolysis was fastest in pigs fed UHT milk (0.29%/min compared with on average 0.07%/min in pigs fed raw, PNH, and PH milk). Differences in the apparent degree of gastric protein hydrolysis and emptying were reflected in the rate of digested protein entering the small intestine. The AA gastric emptying half-time was generally shorter in pigs fed PH and UHT milk than in pigs fed raw and PNH milk. For example, the gastric release of total essential AA was >2-fold faster (P < 0.01) in pigs fed PH or UHT milk than that in pigs fed raw or PNH milk (i.e., homogenized compared with nonhomogenized milk). CONCLUSIONS Heat treatment and homogenization increased the apparent gastric degree of protein hydrolysis and the release of digested protein into the small intestine. However, the rate of AA entering the small intestine was mainly increased by homogenization.
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Affiliation(s)
- Natalie G Ahlborn
- Riddet Institute, Massey University, Palmerston North, New Zealand; School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand; Smart Foods and Bioproducts Group, AgResearch Ltd, Palmerston North, New Zealand
| | - Carlos A Montoya
- Riddet Institute, Massey University, Palmerston North, New Zealand; Smart Foods and Bioproducts Group, AgResearch Ltd, Palmerston North, New Zealand.
| | - Nicole C Roy
- Riddet Institute, Massey University, Palmerston North, New Zealand; High-Value Nutrition National Science Challenge, Auckland, New Zealand; Department of Human Nutrition, University of Otago, Dunedin, New Zealand
| | - Aiqian Ye
- Riddet Institute, Massey University, Palmerston North, New Zealand; School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand
| | - Linda M Samuelsson
- Smart Foods and Bioproducts Group, AgResearch Ltd, Palmerston North, New Zealand
| | - Robert J Wieliczko
- Smart Foods and Bioproducts Group, AgResearch Ltd, Palmerston North, New Zealand
| | - Warren C McNabb
- Riddet Institute, Massey University, Palmerston North, New Zealand; High-Value Nutrition National Science Challenge, Auckland, New Zealand
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2
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Ahlborn NG, Montoya CA, Roy D, Roy NC, Stroebinger N, Ye A, Samuelsson LM, Moughan PJ, McNabb WC. Differences in small intestinal apparent amino acid digestibility of raw bovine, caprine, and ovine milk are explained by gastric amino acid retention in piglets as an infant model. Front Nutr 2023; 10:1226638. [PMID: 37731403 PMCID: PMC10507170 DOI: 10.3389/fnut.2023.1226638] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 08/21/2023] [Indexed: 09/22/2023] Open
Abstract
Background The rate of stomach emptying of milk from different ruminant species differs, suggesting that the small intestinal digestibility of nutrients could also differ across these milk types. Objective To determine the small intestinal amino acid (AA) digestibility of raw bovine, caprine, and ovine milk in the piglet as an animal model for the infant. Methods Seven-day-old piglets (n = 12) consumed either bovine, caprine, or ovine milk diets for 15 days (n = 4 piglets/milk). On day 15, fasted piglets received a single meal of fresh raw milk normalized for protein content and containing the indigestible marker titanium dioxide. Entire gastrointestinal tract contents were collected at 210 min postprandially. Apparent AA digestibility (disappearance) in different regions of the small intestine was determined. Results On average, 35% of the dietary AAs were apparently taken up in the small intestine during the first 210 min post-feeding, with 67% of the AA digestibility occurring in the first quarter (p ≤ 0.05) and 33% in the subsequent two quarters. Overall, except for isoleucine, valine, phenylalanine, and tyrosine, the small intestinal apparent digestibility of all AAs at 210 min postprandially in piglets fed ovine milk was, on average, 29% higher (p ≤ 0.05) than for those fed bovine milk. Except for lysine, there was no difference in the apparent digestibility (p > 0.05) of any AAs between piglets fed caprine milk or ovine milk. The apparent digestibility of alanine was higher (p ≤ 0.05) in piglets fed caprine milk than those fed bovine milk. When apparent digestibility was corrected for gastric AA retention, only small differences in the small intestinal apparent digestibility of AAs were observed across milk types. Conclusion Bovine, caprine and ovine milk had different apparent small intestinal AA digestibility at 210 min postprandially. When corrected for gastric AA retention, the differences in apparent digestibility across species largely disappeared. The apparent AA digestibility differed across small intestinal locations.
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Affiliation(s)
- Natalie G. Ahlborn
- Riddet Institute, Massey University, Palmerston North, New Zealand
- School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand
- Smart Foods and Bioproducts Group, AgResearch Ltd, Palmerston North, New Zealand
| | - Carlos A. Montoya
- Riddet Institute, Massey University, Palmerston North, New Zealand
- Smart Foods and Bioproducts Group, AgResearch Ltd, Palmerston North, New Zealand
| | - Debashree Roy
- Riddet Institute, Massey University, Palmerston North, New Zealand
- School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand
| | - Nicole C. Roy
- Riddet Institute, Massey University, Palmerston North, New Zealand
- Department of Human Nutrition, University of Otago, Dunedin, New Zealand
- High-Value Nutrition National Science Challenge, Auckland, New Zealand
| | | | - Aiqian Ye
- Riddet Institute, Massey University, Palmerston North, New Zealand
- School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand
| | - Linda M. Samuelsson
- Smart Foods and Bioproducts Group, AgResearch Ltd, Palmerston North, New Zealand
| | - Paul J. Moughan
- Riddet Institute, Massey University, Palmerston North, New Zealand
| | - Warren C. McNabb
- Riddet Institute, Massey University, Palmerston North, New Zealand
- High-Value Nutrition National Science Challenge, Auckland, New Zealand
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3
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Teng F, Samuelsson LM, Milan AM, Subbaraj A, Agnew M, Shrestha A, Cameron-Smith D, Day L. Postprandial lipemic response in dairy-avoiding females following an equal volume of sheep milk relative to cow milk: A randomized controlled trial. Front Nutr 2023; 9:1029813. [PMID: 36687710 PMCID: PMC9846784 DOI: 10.3389/fnut.2022.1029813] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Accepted: 11/14/2022] [Indexed: 01/06/2023] Open
Abstract
Background Sheep milk (SM) is an alternate dairy source, which despite many similarities, has both compositional and structural differences in lipids compared to cow milk (CM). Studies are yet to examine the apparent digestibility of SM lipids, relative to CM, and the potential impact on the plasma lipidome. Objective To determine the response of the circulatory lipidome to equal volume servings of SM and CM, in females who avoid dairy products. Method In a double-blinded, randomized, cross-over trial, self-described dairy avoiding females (n = 30; 24.4 ± 1.1 years) drank SM or CM (650 mL; 33.4 vs. 21.3 g total lipid content; reconstituted from spray dried milk powders) following an overnight fast. Blood samples were collected at fasting and at regular intervals over 4 h after milk consumption. The plasma lipidome was analyzed by LC-MS and fatty acids were quantified by GC-FID. Results The overall postprandial triglyceride (TG) response was similar between SM and CM. TG concentrations were comparable at fasting for both groups, however they were higher after CM consumption at 30 min (interaction milk × time p = 0.003), well before any postprandial lipemic response. This was despite greater quantities provided by SM. However, there were notable differences in the postprandial fatty acid response, with SM leading to an increase in short- and medium-chain fatty acids (MCFAs) (C6:0, C8:0, and C10:0) and several long-chain fatty acids (LCFAs) (C18:1 t11, c9, t11-CLA, and C20:0; interaction time × milk p < 0.05). This corresponded to a greater postprandial response for medium chain triglycerides (MCTs) C10:0, including TG(10:0/14:0/18:1), TG(16:0/10:0/12:0), and TG(16:0/10:0/14:0) (interaction time × milk p < 0.05). Conclusions Despite a higher fat content, SM ingestion resulted in a greater circulating abundance of MCTs, without increasing total postprandial triglyceride response, when compared to CM. The greater abundance and postprandial appearance of MCTs may provide advantageous metabolic responses in children and adults. Unique identifier and registry U1111-1209-7768; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375324.
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Affiliation(s)
- Fei Teng
- AgResearch Ltd., Grasslands Research Centre, Palmerston North, New Zealand
| | | | - Amber Marie Milan
- AgResearch Ltd., Grasslands Research Centre, Palmerston North, New Zealand,The Liggins Institute, The University of Auckland, Auckland, New Zealand
| | - Arvind Subbaraj
- AgResearch Ltd., Lincoln Research Center, Lincoln, New Zealand
| | - Michael Agnew
- AgResearch Ltd., Grasslands Research Centre, Palmerston North, New Zealand
| | - Aahana Shrestha
- The Liggins Institute, The University of Auckland, Auckland, New Zealand,Riddet Institute, Palmerston North, New Zealand
| | - David Cameron-Smith
- The Liggins Institute, The University of Auckland, Auckland, New Zealand,AgResearch Ltd., Lincoln Research Center, Lincoln, New Zealand,College of Health, Medicine and Wellbeing, University of Newcastle, Callaghan, NSW, Australia
| | - Li Day
- AgResearch Ltd., Grasslands Research Centre, Palmerston North, New Zealand,*Correspondence: Li Day
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Ahlborn NG, Montoya CA, Hodgkinson SM, Dave A, Ye A, Samuelsson LM, Roy NC, McNabb WC. Heat treatment and homogenization of bovine milk loosened gastric curd structure and increased gastric emptying in growing pigs. Food Hydrocoll 2022. [DOI: 10.1016/j.foodhyd.2022.108380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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5
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Wegrzyn TF, Henare S, Ahlborn N, Ahmed Nasef N, Samuelsson LM, Loveday SM. The plasma amino acid response to blended protein beverages: a randomised crossover trial. Br J Nutr 2022; 128:1555-1564. [PMID: 35105389 DOI: 10.1017/s0007114521004591] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Soya-dairy protein blends can extend post-exercise muscle synthesis in young people more than whey protein control. Older adults differ metabolically from young people, and their ability to absorb amino acids from dietary protein is important for muscle function. The objective was to determine how protein source affects postprandial plasma amino acid response and/or metabolomic profile in older adults via a single-blind randomised crossover trial (n 16, males 50-70 years), using three nutritionally equivalent meal replacement drinks containing 30 g protein, from a 1:1 (mass ratio) soya:dairy blend, a 1:2 soya:dairy blend or whey protein. The outcome measures were plasma amino acid concentrations at 0-300 min postprandially and urine metabolomic fingerprint. Soya:dairy drinks gave similar amino acid response in plasma over time and similar urinary metabolite fingerprints. However, there were significant differences in plasma amino acid concentrations and AUC values for the soya:dairy drinks v. the whey protein drink. AUC for Leu, Trp and Lys was lower and AUC for Phe and Pro was higher for the soya:dairy drinks. Differences partly reflected the amino acid profiles of the drinks, but overall plasma amino acid response patterns were qualitatively unchanged. Plasma amino acid differences between the whey protein drink and the soya:dairy blends were reflected in urine metabolite patterns. In conclusion, postprandial plasma amino acid responses were broadly similar, irrespective of protein source (and soya:dairy ratio). There were significant differences for some plasma amino acid concentrations, reflecting different amino acid profiles of the protein source and influencing urine metabolite fingerprints.
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Affiliation(s)
- Teresa F Wegrzyn
- Riddet Institute, Massey University, Palmerston North4442, New Zealand
| | - Sharon Henare
- School of Health Sciences, College of Health, Massey University, Palmerston North, New Zealand
| | - Natalie Ahlborn
- Smart Foods Innovation Centre of Excellence, AgResearch Limited, Tennent Drive, Palmerston North, New Zealand
| | - Noha Ahmed Nasef
- Riddet Institute, Massey University, Palmerston North4442, New Zealand
| | - Linda M Samuelsson
- Smart Foods Innovation Centre of Excellence, AgResearch Limited, Tennent Drive, Palmerston North, New Zealand
| | - Simon M Loveday
- Riddet Institute, Massey University, Palmerston North4442, New Zealand
- Smart Foods Innovation Centre of Excellence, AgResearch Limited, Tennent Drive, Palmerston North, New Zealand
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Samuelsson LM, Smolenski G, Boggs I, Choe J, Farouk MM, Brad Kim YH. Metabolomic and proteomic characterisation of aged and packaged lamb loins with different colour stability. J Food Compost Anal 2022. [DOI: 10.1016/j.jfca.2022.104639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Soni A, Samuelsson LM, Loveday SM, Gupta TB. Applications of novel processing technologies to enhance the safety and bioactivity of milk. Compr Rev Food Sci Food Saf 2021; 20:4652-4677. [PMID: 34427048 DOI: 10.1111/1541-4337.12819] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 02/11/2021] [Revised: 06/16/2021] [Accepted: 07/07/2021] [Indexed: 01/20/2023]
Abstract
Bioactive compounds in food can have high impacts on human health, such as antioxidant, antithrombotic, antitumor, and anti-inflammatory activities. However, many of them are sensitive to thermal treatments incurred during processing, which can reduce their availability and activity. Milk, including ovine, caprine, bovine, and human is a rich source of bioactive compounds, including immunoglobulins, vitamins, and amino acids. However, processing by various novel thermal and non-thermal technologies has different levels of impacts on these compounds, according to the studies reported in the literature, predominantly in the last 10 years. The reported effect of these technologies either covers microbial inactivation or the bioactive composition; however, there is a lack of comprehensive compilation of studies that compare the effect of these technologies on bioactive compounds in milk (especially, caprine and ovine) to microbial inactivation at similar settings. This research gap makes it challenging to conclude on the specific processing parameters that could be optimized to achieve targets of microbial safety and nutritional quality at the same time. This review covers the effect of a wide range of thermal and non-thermal processing technologies including high-pressure processing, pressure-assisted thermal sterilization, pulsed-electric field treatment, cold plasma, microwave-assisted thermal sterilization, ultra-high-pressure homogenization, ultrasonication, irradiation on the bioactive compounds as well as on microbial inactivation in milk. Although a combination of more than one technology could improve the reduction of bacterial contaminants to meet the required food safety standards and retain bioactive compounds, there is still scope for research on these hurdle approaches to simultaneously achieve food safety and bioactivity targets.
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Affiliation(s)
- Aswathi Soni
- Food System Integrity, Consumer Food Interface, AgResearch Ltd, Palmerston North, New Zealand
| | - Linda M Samuelsson
- Smart Foods Innovation Centre of Excellence, AgResearch Ltd, Palmerston North, New Zealand
| | - Simon M Loveday
- Smart Foods Innovation Centre of Excellence, AgResearch Ltd, Palmerston North, New Zealand.,Riddet Institute, Massey University, Palmerston North, New Zealand
| | - Tanushree B Gupta
- Food System Integrity, Consumer Food Interface, AgResearch Ltd, Palmerston North, New Zealand
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8
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Cônsolo NRB, Silva J, Buarque VLM, Samuelsson LM, Miller P, Maclean PH, Moraes TB, Barbosa LCGS, Higuera-Padilla A, Colnago LA, Saran Netto A, Gerrard DE, Silva SL. Using TD-NMR relaxometry and 1D 1H NMR spectroscopy to evaluate aging of Nellore beef. Meat Sci 2021; 181:108606. [PMID: 34146920 DOI: 10.1016/j.meatsci.2021.108606] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 12/27/2020] [Revised: 06/05/2021] [Accepted: 06/10/2021] [Indexed: 10/21/2022]
Abstract
The aim of this study was to explore the use of TD-NMR relaxometry and 1H NMR spectroscopy-based for detecting differences in meat quality attributes. There was limited association between various TD-NMR signals and any physicochemical parameters of fresh and aged meat differing in tenderness ratings. Samples were then divided into three groups based on statistical changes in metabolite concentration. Group A samples possessed near linear increases in metabolite concentration over aging time; whereas samples assigned to Groups B and C were characterized by increases in metabolites that peaked between 7 and 14 days, and up to 14 days aging, respectively. 1H NMR spectroscopy discriminated meat quality using changes in metabolites reflective of glycolysis, the citric acid cycle, protein degradation, amino acid generation and purine metabolisms. These data suggest segregation of meat quality is possible using both NMR technologies but additional work is necessary to understand fully their utility in a commercial industry setting.
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Affiliation(s)
- Nara R B Cônsolo
- Universidade de São Paulo, Faculdade de Zootecnia e Engenharia de Alimentos (FZEA-USP), Duque de Caxias Norte 225, Pirassununga, SP 13635-900, Brazil.
| | - Juliana Silva
- Universidade de São Paulo, Faculdade de Zootecnia e Engenharia de Alimentos (FZEA-USP), Duque de Caxias Norte 225, Pirassununga, SP 13635-900, Brazil.
| | - Vicente L M Buarque
- Universidade de São Paulo, Faculdade de Zootecnia e Engenharia de Alimentos (FZEA-USP), Duque de Caxias Norte 225, Pirassununga, SP 13635-900, Brazil.
| | - Linda M Samuelsson
- AgResearch, Grasslands Research Centre, Tennent Drive, 11 Dairy Farm Rd, Palmerston North 4442, New Zealand.
| | - Poppy Miller
- AgResearch, Grasslands Research Centre, Tennent Drive, 11 Dairy Farm Rd, Palmerston North 4442, New Zealand.
| | - Paul H Maclean
- AgResearch, Grasslands Research Centre, Tennent Drive, 11 Dairy Farm Rd, Palmerston North 4442, New Zealand.
| | - Tiago B Moraes
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais (UFMG), Av. Antônio Carlos 6627, Belo Horizonte, MG 31270-901, Brazil.
| | - Luis C G S Barbosa
- EMBRAPA Instrumentação, XV de Novembro 1452, São Carlos, SP 13560-970, Brazil.
| | | | - Luiz A Colnago
- EMBRAPA Instrumentação, XV de Novembro 1452, São Carlos, SP 13560-970, Brazil.
| | - Arlindo Saran Netto
- Universidade de São Paulo, Faculdade de Zootecnia e Engenharia de Alimentos (FZEA-USP), Duque de Caxias Norte 225, Pirassununga, SP 13635-900, Brazil.
| | - David E Gerrard
- Virginia Polytechnic Institute and State University, Department of Animal and Poultry Sciences, 3480 Litton-Reaves Hall, Blacksburg, VA 24061, United States.
| | - Saulo L Silva
- Universidade de São Paulo, Faculdade de Zootecnia e Engenharia de Alimentos (FZEA-USP), Duque de Caxias Norte 225, Pirassununga, SP 13635-900, Brazil.
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Shrestha A, Samuelsson LM, Sharma P, Day L, Cameron-Smith D, Milan AM. Comparing Response of Sheep and Cow Milk on Acute Digestive Comfort and Lactose Malabsorption: A Randomized Controlled Trial in Female Dairy Avoiders. Front Nutr 2021; 8:603816. [PMID: 33659266 PMCID: PMC7917135 DOI: 10.3389/fnut.2021.603816] [Citation(s) in RCA: 6] [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: 09/08/2020] [Accepted: 01/22/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Sheep milk (SM) is a possible alternate dairy source for those who experience digestive symptoms with cow milk (CM). While both the milks contain lactose, one of the causes for self-reported intolerance to CM, the composition of SM and CM also differs across proteins and fats, which have been shown to impact digestive processes. Objective: To compare the acute digestive comfort and lactose malabsorption of SM to CM in female dairy avoiders. Method: In a double-blinded, randomized cross over trial, 30 dairy-avoiding females (aged 20-30 years) drank 650 mL of SM or CM (each reconstituted from spray dried powder) following an overnight fast, on two separate occasions at least 1 week apart. Blood samples were collected for glucose and insulin assessment, and single nucleotide polymorphisms of the lactase (LCT) gene (C/T13910 and G/A22018). Breath H2 and visual analog scale (VAS) digestive symptom scores were recorded at fasting and regular intervals over 4 h after ingestion. Results: Eighty percentage of study participants were lactase non-persistent (LNP; CC13910 and GG22018 genotype). Digestive symptoms, including abdominal cramps, distension, rumbling, bloating, belching, diarrhea, flatulence, vomiting, and nausea, were similar in response to SM and CM ingestion (milk × time, P > 0.05). Breath H2 was greater after CM than SM (72 ± 10 vs. 43 ± 6 ppm at 240 min, P < 0.001), which may be due to greater lactose content in CM (33 vs. 25 g). Accordingly, when corrected for the lactose content breath H2 did not differ between the two milks. The response remained similar when analyzed in the LNP subset alone (n = 20). Conclusions: Despite a higher energy and nutrient content, SM did not increase adverse digestive symptoms after ingestion, relative to CM, although there was a reduced breath H2 response, which could be attributed to the lower lactose content in SM. The tolerability of SM should be explored in populations without lactose intolerance for whom underlying trigger for intolerance is unknown.
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Affiliation(s)
- Aahana Shrestha
- The Liggins Institute, The University of Auckland, Auckland, New Zealand.,Riddet Institute, Palmerston North, New Zealand
| | | | - Pankaja Sharma
- The Liggins Institute, The University of Auckland, Auckland, New Zealand.,Riddet Institute, Palmerston North, New Zealand
| | - Li Day
- AgResearch Ltd., Te Ohu Rangahau Kai, Palmerston North, New Zealand
| | - David Cameron-Smith
- The Liggins Institute, The University of Auckland, Auckland, New Zealand.,Riddet Institute, Palmerston North, New Zealand.,Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research, Singapore, Singapore
| | - Amber M Milan
- The Liggins Institute, The University of Auckland, Auckland, New Zealand.,AgResearch Ltd., Te Ohu Rangahau Kai, Palmerston North, New Zealand
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10
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Milan AM, Samuelsson LM, Shrestha A, Sharma P, Day L, Cameron-Smith D. Circulating Branched Chain Amino Acid Concentrations Are Higher in Dairy-Avoiding Females Following an Equal Volume of Sheep Milk Relative to Cow Milk: A Randomized Controlled Trial. Front Nutr 2020; 7:553674. [PMID: 33240914 PMCID: PMC7678490 DOI: 10.3389/fnut.2020.553674] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [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: 05/22/2020] [Accepted: 10/07/2020] [Indexed: 12/23/2022] Open
Abstract
Background: Intolerances to bovine dairy are a motivating factor in consumers seeking alternate-or replacement-dairy beverages and foods. Sheep milk (SM) is an alternate dairy source, with greater protein, although similar amino acid composition compared to cow milk (CM). Studies are yet to address the appearance of circulating amino acids following consumption of SM, relative to CM, in humans. Objective: To clinically determine the appearance of branched chain amino acids, and other amino acids, in circulation in response to equal servings of SM and CM, in females who avoid dairy products. Design: In a double-blinded, randomized, cross-over trial, 30 self-described dairy avoiding females (20-40 years) drank 650 mL of SM or CM that were reconstituted from the spray dried powders (30 and 25 g in 180 mL water, respectively) on separate occasions, following an overnight fast. After reconstitution, the energy and protein provided by SM was higher than for CM (2,140 vs. 1,649 kJ; 29.9 vs. 19.4 g protein); content of branched chain amino acids (BCAAs) were 10.5 and 6.5 mg·mL-1, respectively. Blood samples were collected at fasting and at regular intervals over 5 h after milk consumption. Plasma amino acids were measured by HPLC. Results: 80% of subjects self-identified as lactose intolerant, and the majority (47%) "avoided drinking milk" "most of the time". SM resulted in greater plasma appearance of BCAAs at 60 min (641.1 ± 16.3 vs. 563.5 ± 14.4 μmol·L-1; p < 0.001) compared with CM. SM similarly resulted in elevated postprandial concentrations of the amino acids lysine, methionine, and proline, particularly at 240 min (time × milk interactions p = 0.011, 0.017, and p = 0.002, respectively). Postprandial increases in plasma alanine concentrations were sustained to 120 min after CM (time × milk interaction p = 0.001) but not after SM, despite greater quantities provided by SM. Conclusions: SM is a rich source of protein, and relative to CM, provides a greater quantity of BCAAs, with a corresponding elevation of the postprandial circulating BCAA response. SM is therefore a possible dairy alternative of benefit to those who need to increase total protein intake or for individuals with heightened protein requirements. Unique Identifier and Registry: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375324, identifier U1111-1209-7768.
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Affiliation(s)
- Amber M. Milan
- The Liggins Institute, The University of Auckland, Auckland, New Zealand
- AgResearch Ltd, Grasslands Research Center, Palmerston North, New Zealand
| | | | - Aahana Shrestha
- The Liggins Institute, The University of Auckland, Auckland, New Zealand
- Riddet Institute, Palmerston North, New Zealand
| | - Pankaja Sharma
- The Liggins Institute, The University of Auckland, Auckland, New Zealand
- Riddet Institute, Palmerston North, New Zealand
| | - Li Day
- AgResearch Ltd, Grasslands Research Center, Palmerston North, New Zealand
| | - David Cameron-Smith
- The Liggins Institute, The University of Auckland, Auckland, New Zealand
- AgResearch Ltd, Grasslands Research Center, Palmerston North, New Zealand
- Riddet Institute, Palmerston North, New Zealand
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11
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Cônsolo NRB, Samuelsson LM, Barbosa LCGS, Monaretto T, Moraes TB, Buarque VLM, Higuera-Padilla AR, Colnago LA, Silva SL, Reis MM, Fonseca AC, Araújo CSDS, Leite BGDS, Roque FA, Araújo LF. Characterization of chicken muscle disorders through metabolomics, pathway analysis, and water relaxometry: a pilot study. Poult Sci 2020; 99:6247-6257. [PMID: 33142543 PMCID: PMC7647706 DOI: 10.1016/j.psj.2020.06.066] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 06/18/2020] [Accepted: 06/29/2020] [Indexed: 02/06/2023] Open
Abstract
Metabolite profiles of chicken breast extracts and water mobility in breasts were studied using proton nuclear magnetic resonance (1H-NMR) spectroscopy and time-domain NMR (TD-NMR) relaxometry, respectively, using normal breast (NB), and wooden breast (WB) and white striping (WS) myopathies in broilers. One thousand eight hundred sixty broilers were raised to commercial standards, receiving the same diets that were formulated as per the different growth stages. At 49 D of age, 200 animals were slaughtered following routine commercial procedures, and at 4 h postmortem, the whole breast (pectoralis major muscle) was removed and visually inspected by an experienced meat inspector who selected NB (without myopathies) and samples with the presence of WS and WB myopathies. Fifteen breasts (5 each of NB, WS, and WB) were analyzed through TD-NMR relaxometry, and samples of approximately 20 g were taken from each breast and frozen at -80°C for metabolite profiling through 1H-NMR spectroscopy. Multivariate statistical analysis was used to evaluate the effect on water relaxometry and metabolite profile in accordance with the presence and type of myopathy in the breast. 1H-NMR data showed that the metabolite profiles in WS and WB breasts were different from each other and from NB. This pilot study shows that myopathies appear to be related to hypoxia, connective tissue deposition, lower mitochondrial function, and greater oxidative stress compared with NB. The longitudinal and transverse relaxation time of the breasts determined by TD-NMR relaxometry was shorter for NB than that for WS and WB, indicating greater water mobility in breasts affected by myopathies. 1H-NMR spectroscopy can be used to differentiate the metabolism of WS, WB, and NB, and TD-NMR has the potential to be a fast, simple, and noninvasive method to distinguish NB from WB and WS. As a practical application, the metabolomic profile as per the occurrence of breast myopathies may be used for a better understanding of these issues, which opens a gap to mitigate the incidence and severity of WS and WB. In addition, the present study brings an opportunity for the development of a new and objective tool to classify the incidence of breast myopathies through TD-NMR relaxometry.
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Affiliation(s)
- Nara R B Cônsolo
- Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga 13635-900, SP, Brazil
| | - Linda M Samuelsson
- AgResearch, Grasslands Research Centre, Palmerston North 4442, New Zealand
| | - Luís C G S Barbosa
- School of Veterinary Medicine and Animal Sciences, University of São Paulo, Pirassununga 13635-900, SP, Brazil
| | - Tatiana Monaretto
- São Carlos Institute of Chemistry, University of São Paulo, São Carlos 13566-590, SP, Brazil
| | - Tiago B Moraes
- Department of Chemistry, Institute of Exact Sciences, Federal University of Minas Gerais, Belo Horizonte 31270-901, MG, Brazil
| | - Vicente L M Buarque
- Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga 13635-900, SP, Brazil
| | | | - Luiz A Colnago
- EMBRAPA Instrumentação, São Carlos 13560-970, SP, Brazil
| | - Saulo L Silva
- Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga 13635-900, SP, Brazil
| | - Marlon M Reis
- AgResearch, Grasslands Research Centre, Palmerston North 4442, New Zealand
| | - André C Fonseca
- School of Veterinary Medicine and Animal Sciences, University of São Paulo, Pirassununga 13635-900, SP, Brazil
| | - Cristiane S da S Araújo
- School of Veterinary Medicine and Animal Sciences, University of São Paulo, Pirassununga 13635-900, SP, Brazil
| | - Bruna G de S Leite
- Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga 13635-900, SP, Brazil
| | - Fabricia A Roque
- Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga 13635-900, SP, Brazil
| | - Lúcio F Araújo
- Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga 13635-900, SP, Brazil.
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Cônsolo NR, Olivecrona N, Samuelsson LM, Reis MG, Edwards PJ, Reis MM. Investigation of metabolites associated with confinement odour in chilled vacuum-packed lamb by proton nuclear magnetic resonance (1H NMR) spectroscopy. Meat Sci 2020; 169:108207. [DOI: 10.1016/j.meatsci.2020.108207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 06/02/2020] [Accepted: 06/02/2020] [Indexed: 02/04/2023]
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Ahlborn N, Young W, Mullaney J, Samuelsson LM. In Vitro Fermentation of Sheep and Cow Milk Using Infant Fecal Bacteria. Nutrients 2020; 12:E1802. [PMID: 32560419 PMCID: PMC7353214 DOI: 10.3390/nu12061802] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [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: 04/30/2020] [Revised: 06/03/2020] [Accepted: 06/07/2020] [Indexed: 12/15/2022] Open
Abstract
While human milk is the optimal food for infants, formulas that contain ruminant milk can have an important role where breastfeeding is not possible. In this regard, cow milk is most commonly used. However, recent years have brought interest in other ruminant milk. While many similarities exist between ruminant milk, there are likely enough compositional differences to promote different effects in the infant. This may include effects on different bacteria in the large bowel, leading to different metabolites in the gut. In this study sheep and cow milk were digested using an in vitro infant digestive model, followed by fecal fermentation using cultures inoculated with fecal material from two infants of one month and five months of age. The effects of the cow and sheep milk on the fecal microbiota, short-chain fatty acids (SCFA), and other metabolites were investigated. Significant differences in microbial, SCFA, and metabolite composition were observed between fermentation of sheep and cow milk using fecal inoculum from a one-month-old infant, but comparatively minimal differences using fecal inoculum from a five-month-old infant. These results show that sheep milk and cow milk can have differential effects on the gut microbiota, while demonstrating the individuality of the gut microbiome.
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Affiliation(s)
- Natalie Ahlborn
- AgResearch Ltd., Grasslands Research Centre, Palmerston North 4442, New Zealand; (N.A.); (W.Y.); (J.M.)
- Faculty of Life Sciences, Rhine-Waal University of Applied Sciences, 47533 Kleve, Germany
| | - Wayne Young
- AgResearch Ltd., Grasslands Research Centre, Palmerston North 4442, New Zealand; (N.A.); (W.Y.); (J.M.)
- Riddet Institute, Massey University, Palmerston North 4474, New Zealand
- High Value Nutrition, National Science Challenges, The Liggins Institute at the University of Auckland, Auckland 1010, New Zealand
| | - Jane Mullaney
- AgResearch Ltd., Grasslands Research Centre, Palmerston North 4442, New Zealand; (N.A.); (W.Y.); (J.M.)
- Riddet Institute, Massey University, Palmerston North 4474, New Zealand
- High Value Nutrition, National Science Challenges, The Liggins Institute at the University of Auckland, Auckland 1010, New Zealand
| | - Linda M. Samuelsson
- AgResearch Ltd., Grasslands Research Centre, Palmerston North 4442, New Zealand; (N.A.); (W.Y.); (J.M.)
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Kim YHB, Kemp R, Samuelsson LM. Effects of dry-aging on meat quality attributes and metabolite profiles of beef loins. Meat Sci 2015; 111:168-76. [PMID: 26437054 DOI: 10.1016/j.meatsci.2015.09.008] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [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: 05/06/2015] [Revised: 08/10/2015] [Accepted: 09/23/2015] [Indexed: 01/14/2023]
Abstract
The objectives of this study were to evaluate different dry-aging regimes and their impacts on quality attributes and metabolite profiles of beef loins. Thirty loins (M. longissimus lumborum) from 15 beef carcasses at 2 days post-mortem were obtained. Each loin was cut in half yielding 60 sections, which were randomly assigned to six treatments including 4 dry-aging (2 temperatures (1 or 3°C) × 2 air-velocities (0.2 or 0.5 m/s)) and 2 wet-aging regimes for 3 weeks; n=10/treatment. The sensory panel found that dry-aged loins had better flavour and overall liking (P<0.05), but there were no differences in tenderness and juiciness. No differences in drip/cook-loss and colour were observed. Metabolite analysis showed that 7 metabolites, including several flavour precursors, were more abundant in the dry-aged beef compared to the wet-aged beef, which may contribute to the enhanced flavours of the dry-aged beef. Overall, dry-aging loins at 3°C with 0.2m/s resulted in the greatest improvement in beef palatability.
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Affiliation(s)
- Yuan H Brad Kim
- AgResearch Ltd., Ruakura Research Centre, Bisley Road, Private Bag 3123, Hamilton 3240, New Zealand; Meat Science and Muscle Biology Laboratory, Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Robert Kemp
- AgResearch Ltd., Ruakura Research Centre, Bisley Road, Private Bag 3123, Hamilton 3240, New Zealand
| | - Linda M Samuelsson
- AgResearch Ltd., Grasslands Research Centre, Tennent Drive, Private Bag 11008, Palmerston North 4412, New Zealand.
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Samuelsson LM, Björlenius B, Förlin L, Larsson DGJ. Reproducible (1)H NMR-based metabolomic responses in fish exposed to different sewage effluents in two separate studies. Environ Sci Technol 2011; 45:1703-1710. [PMID: 21261249 DOI: 10.1021/es104111x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Treated sewage effluents contain complex mixtures of micropollutants, raising concerns about effects on aquatic organisms. The addition of advanced treatment steps has therefore been suggested. However, some of these could potentially produce effluents affecting exposed organisms by unknown modes of action. Here, (1)H NMR (proton nuclear magnetic resonance spectroscopy) metabolomics of fish blood plasma was used to explore potential responses not identified by more targeted (chemical or biological) assays. Rainbow trout was exposed in parallel to six differently treated effluents (e.g., conventional activated sludge, addition of sand filter, further addition of ozonation and/or a moving bed biofilm reactor or a separate membrane bioreactor line). Multivariate data analysis showed changes in the metabolome (HDL, LDL, VLDL and glycerol-containing lipids, cholesterol, glucose, phosphatidylcholine, glutamine, and alanine) between treatment groups. This formed the basis for postulating a hypothesis on how exposure to effluent treated by certain processes, including ozonation, would affect the metabolic profiles of exposed fish. The hypothesis withstood testing in an independent study the following year. To conclude, (1)H NMR metabolomics proved suitable for identifying physiological responses not identified by more targeted assays used in parallel studies. Whether these changes are linked to adverse effects remains to be tested.
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Affiliation(s)
- Linda M Samuelsson
- Institute of Neuroscience and Physiology, Department of Physiology, The Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
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Kullgren A, Samuelsson LM, Larsson DGJ, Björnsson BT, Bergman EJ. A metabolomics approach to elucidate effects of food deprivation in juvenile rainbow trout (Oncorhynchus mykiss). Am J Physiol Regul Integr Comp Physiol 2010; 299:R1440-8. [DOI: 10.1152/ajpregu.00281.2010] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The aim of this study was to evaluate whether NMR-based metabolomics is a suitable method to generate an integrated view on metabolic processes during food deprivation in salmonid fish. Juvenile rainbow trout ( Oncorhynchus mykiss ) weighing 43–115 g were either fed ad libitum or deprived of food for 28 days at 10°C to investigate catabolic effects on energy reserves and metabolite patterns. The NMR analysis of plasma, liver, and muscle extracts revealed significant fasting-induced changes in the metabolome. Altered plasma lipoprotein levels and tissue-specific patterns of fatty acid mobilization were the most prominent responses, emphasizing the role of lipids as the primary energy source during fasting. In plasma, very-low-density lipoprotein levels increased in food-deprived fish compared with fed fish, whereas levels of high-density lipoprotein decreased. Signs of muscle protein catabolism were also observed as changes in the alanine dynamics. The results further suggest that mechanisms to preserve liver glycogen are present in the food-deprived fish. This study thus demonstrates the utility of NMR-based metabolomics of tissue extracts and plasma to describe the integrated metabolic status of fish.
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Affiliation(s)
- Andreas Kullgren
- Fish Endocrinology Laboratory, Department of Zoology/Zoophysiology, University of Gothenburg; and
| | - Linda M. Samuelsson
- Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - D. G. Joakim Larsson
- Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Björn Thrandur Björnsson
- Fish Endocrinology Laboratory, Department of Zoology/Zoophysiology, University of Gothenburg; and
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18
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Blaikie FH, Brown SE, Samuelsson LM, Brand MD, Smith RAJ, Murphy MP. Targeting Dinitrophenol to Mitochondria: Limitations to the Development of a Self-limiting Mitochondrial Protonophore. Biosci Rep 2006; 26:231-43. [PMID: 16850251 DOI: 10.1007/s10540-006-9018-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The protonmotive force (Δp) across the mitochondrial inner membrane drives ATP synthesis. In addition, the energy stored in Δp can be dissipated by proton leak through the inner membrane, contributing to basal metabolic rate and thermogenesis. Increasing mitochondrial proton leak pharmacologically should decrease the efficiency of oxidative phosphorylation and counteract obesity by enabling fatty acids to be oxidised with decreased ATP production. While protonophores such as 2,4-dinitrophenol (DNP) increase mitochondrial proton leak and have been used to treat obesity, a slight increase in DNP concentration above the therapeutically effective dose disrupts mitochondrial function and leads to toxicity. Therefore we set out to develop a less toxic protonophore that would increase proton leak significantly at high Δp but not at low Δp. Our design concept for a potential self-limiting protonophore was to couple the DNP moiety to the lipophilic triphenylphosphonium (TPP) cation and this was achieved by the preparation of 3-(3,5-dinitro-4-hydroxyphenyl)propyltriphenylphosphonium methanesulfonate (MitoDNP). TPP cations accumulate within mitochondria driven by the membrane potential (Δψ), the predominant component of Δp. Our hypothesis was that MitoDNP would accumulate in mitochondria at high Δψ where it would act as a protonophore, but that at lower Δψ the accumulation and uncoupling would be far less. We found that MitoDNP was extensively taken into mitochondria driven by Δψ. However MitoDNP did not uncouple mitochondria as judged by its inability to either increase respiration rate or decrease Δψ. Therefore MitoDNP did not act as a protonophore, probably because the efflux of deprotonated MitoDNP was inhibited.
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Affiliation(s)
- Frances H Blaikie
- Department of Chemistry, University of Otago, P O Box 56, Dunedin, New Zealand
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Samuelsson LM, Förlin L, Karlsson G, Adolfsson-Erici M, Larsson DGJ. Using NMR metabolomics to identify responses of an environmental estrogen in blood plasma of fish. Aquat Toxicol 2006; 78:341-9. [PMID: 16762427 DOI: 10.1016/j.aquatox.2006.04.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 04/18/2006] [Accepted: 04/19/2006] [Indexed: 05/10/2023]
Abstract
Nuclear magnetic resonance (NMR) based metabolomics in combination with multivariate data analysis may become valuable tools to study environmental effects of pharmaceuticals and other chemicals in aquatic organisms. To explore the usefulness of this approach in fish, we have used 1H NMR metabolomics to compare blood plasma and plasma lipid extracts from rainbow trout exposed to the synthetic contraceptive estrogen ethinylestradiol (EE2) with plasma from control fish. The plasma metabolite profile was affected in fish exposed to 10 ng/L but not 0.87 ng/L of EE2, which was in agreement with an induced vitellogenin synthesis in the high dose group only, as measured by ELISA. The main affected metabolites were vitellogenin, alanine, phospholipids and cholesterol. The responses identified by this discovery-driven method could be put in context with previous knowledge of the effects of estrogens on fish. This adds confidence to the approach of using NMR metabolomics to identify environmental effects of pharmaceuticals and other contaminants.
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Affiliation(s)
- Linda M Samuelsson
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at Göteborg University, Box 434, SE-405 30 Göteborg, Sweden
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Samuelsson LM, Bedford JJ, Smith RAJ, Leader JP. A comparison of the counteracting effects of glycine betaine and TMAO on the activity of RNase A in aqueous urea solution. Comp Biochem Physiol A Mol Integr Physiol 2005; 141:22-8. [PMID: 15886035 DOI: 10.1016/j.cbpb.2005.03.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2004] [Revised: 03/07/2005] [Accepted: 03/08/2005] [Indexed: 11/16/2022]
Abstract
Trimethylamine-N-oxide (TMAO) and glycine betaine are counteracting osmolytes found in cellular systems under osmotic stress, often in association with high urea concentrations. TMAO is a characteristic component of cartilaginous fish and marine molluscs, while glycine betaine is more widely distributed, occurring in plants, bacteria and the mammalian kidney. As part of a project to explain and understand the action of these methylamines, the RNase A-catalysed degradation of polyuridylic acid in the presence of urea and various osmolytes (0-1.0 M) was studied using (31)P Nuclear Magnetic Resonance spectroscopy. The decrease in reaction rate induced by urea could be fully recovered with 1 molar equivalent of trimethylamine-N-oxide or 1.4 molar equivalents of glycine betaine. These results indicate that the modification of RNase A activity induced by urea is not associated with gross irreversible structural changes and that both glycine betaine and trimethylamine-N-oxide have kinetically detectable counteracting effects.
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Affiliation(s)
- L M Samuelsson
- Department of Physiology, University of Otago Medical School, University of Otago, P.O. Box 913, Dunedin 9001, New Zealand
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