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Crawford SG, Coker RH, Rea LD. Preliminary comparisons between a point-of-care ketometer and reference method using Steller sea lion pup whole blood and plasma. CONSERVATION PHYSIOLOGY 2024; 12:coad104. [PMID: 38293642 PMCID: PMC10823332 DOI: 10.1093/conphys/coad104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 11/27/2023] [Accepted: 12/12/2023] [Indexed: 02/01/2024]
Abstract
We evaluated the Precision Xtra™ ketometer as part of a larger study categorizing fasting status of free-ranging Steller sea lion (Eumetopias jubatus; SSL) pups which necessitated the identification of plasma β-hydroxybutyrate concentrations ([β-HBA]) around a threshold of <0.3 and ≥0.3 mmol/l. Whole blood samples mixed with sodium heparin (NaHep) or ethylenediaminetetraacetic acid liquid anticoagulants were tested <10 minutes after collection (n = 14; triplicate technical replicates). Plasma (stored at -80°C, NaHep, Thaw1) measured via our laboratory's Reference Assay (Sigma Aldrich, St. Louis, MO, Kit #MAK041) served as the standard [β-HBA] for ketometer comparisons. Our observed β-HBA range (0.0-1.6 mmol/l), consistent with published [β-HBA] of free-ranging Otariid pups, represented the lower 20% of the ketometer's range (0.0-8.0 mmol/l). The maximal coefficient of variation (%CV) of ketometer technical replicates was 9.1% (NaHep, whole blood). The majority of ketometer technical replicate sets (84%, including all matrices, anticoagulants and thawings) were identical (CV = 0%). We found linear relationships and agreement of ketometer [β-HBA] between whole blood preserved with different anticoagulants and between whole blood and plasma (Thaw1) measurements. The ketometer produced results with linearity to the Reference Assay for both whole blood and plasma (Thaw1). We identified a non-linear relationship between plasma at Thaw1 and Thaw2 (tested four months apart, NaHep), as only samples with higher SSL [β-HBA] decreased in concentration, and all others remained the same. With respect to categorizing SSL pup fasting in our larger study, the ketometer's %Accuracy, %Sensitivity and %Specificity for samples with Reference Assay β-HBA <0.2 and >0.4 mmol/l were 100%. We adopted a modified procedure: plasma samples with mean ketometer concentrations ±0.1 mmol/l of 0.3 mmol/l β-HBA were re-evaluated using the Reference Assay, improving measurement precision from tenths (ketometer) to thousandths (assay) mmol/l. The Precision Xtra™ ketometer was valuable to our application over the range of [β-HBA] observed in SSL pup plasma and whole blood samples.
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Affiliation(s)
- Stephanie G Crawford
- Department of Biology and Wildlife and Institute of Northern Engineering, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, Alaska 99775, USA
| | - Robert H Coker
- Montana Center for Work Physiology and Exercise Metabolism, University of Montana, 101 McGill Hall, 32 Campus Drive, Missoula, Montana 59812, USA
| | - Lorrie D Rea
- Institute of Northern Engineering, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, Alaska 99775, USA
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Skinner JP, Tuomi PA, Mellish JAE. The influence of time in captivity, food intake and acute trauma on blood analytes of juvenile Steller sea lions, Eumetopias jubatus. CONSERVATION PHYSIOLOGY 2015; 3:cov008. [PMID: 27293693 PMCID: PMC4778467 DOI: 10.1093/conphys/cov008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 01/31/2015] [Accepted: 02/02/2015] [Indexed: 06/06/2023]
Abstract
The Steller sea lion, Eumetopias jubatus, has experienced regionally divergent population trends over recent decades. One potential mechanism for this disparity is that local factors cause reduced health and, therefore, reduced survival of individuals. The use of blood parameters to assess sea lion health may help to identify whether malnutrition, disease and stress are important drivers of current trends, but such assessments require species-specific knowledge of how parameters respond to various health challenges. We used principal components analysis to identify which key blood parameters (principal analytes) best described changes in health for temporarily captive juvenile Steller sea lions in known conditions. Generalized additive mixed models were used to estimate the changes in principal analytes with food intake, time in captivity and acute trauma associated with hot-iron branding and transmitter implant surgery. Of the 17 blood parameters examined, physiological changes for juvenile sea lions were best described using the following six principal analytes: red blood cell counts, white blood cell counts, globulin, platelets, glucose and total bilirubin. The white blood cell counts and total bilirubin declined over time in captivity, whereas globulin increased. Elevated red blood cell counts, white blood cell counts and total bilirubin and reduced globulin values were associated with lower food intake. After branding, white blood cell counts were elevated for the first 30 days, while globulin and platelets were elevated for the first 15 days only. After implant surgery, red blood cell counts and globulin remained elevated for 30 days, while white blood cell counts remained elevated during the first 15 days only. Glucose was unassociated with the factors we studied. These results were used to provide expected ranges for principal analytes at different levels of food intake and in response to the physical challenges of branding and implant surgery. These results provide a more detailed reference for future evaluations of health-related assessments.
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Affiliation(s)
| | - Pam A. Tuomi
- Alaska SeaLife Center, Box 1329, Seward, AK 99664, USA
| | - Jo-Ann E. Mellish
- Alaska SeaLife Center, Box 1329, Seward, AK 99664, USA
- School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
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Houser DS, Champagne CD, Crocker DE. A non-traditional model of the metabolic syndrome: the adaptive significance of insulin resistance in fasting-adapted seals. Front Endocrinol (Lausanne) 2013; 4:164. [PMID: 24198811 PMCID: PMC3814516 DOI: 10.3389/fendo.2013.00164] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 10/17/2013] [Indexed: 11/13/2022] Open
Abstract
Insulin resistance in modern society is perceived as a pathological consequence of excess energy consumption and reduced physical activity. Its presence in relation to the development of cardiovascular risk factors has been termed the metabolic syndrome, which produces increased mortality and morbidity and which is rapidly increasing in human populations. Ironically, insulin resistance likely evolved to assist animals during food shortages by increasing the availability of endogenous lipid for catabolism while protecting protein from use in gluconeogenesis and eventual oxidation. Some species that incorporate fasting as a predictable component of their life history demonstrate physiological traits similar to the metabolic syndrome during prolonged fasts. One such species is the northern elephant seal (Mirounga angustirostris), which fasts from food and water for periods of up to 4 months. During this time, ∼90% of the seals metabolic demands are met through fat oxidation and circulating non-esterified fatty acids are high (0.7-3.2 mM). All life history stages of elephant seal studied to date demonstrate insulin resistance and fasting hyperglycemia as well as variations in hormones and adipocytokines that reflect the metabolic syndrome to some degree. Elephant seals demonstrate some intriguing adaptations with the potential for medical advancement; for example, ketosis is negligible despite significant and prolonged fatty acid oxidation and investigation of this feature might provide insight into the treatment of diabetic ketoacidosis. The parallels to the metabolic syndrome are likely reflected to varying degrees in other marine mammals, most of which evolved on diets high in lipid and protein content but essentially devoid of carbohydrate. Utilization of these natural models of insulin resistance may further our understanding of the pathophysiology of the metabolic syndrome in humans and better assist the development of preventative measures and therapies.
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Affiliation(s)
- Dorian S. Houser
- Department of Conservation and Biological Research, National Marine Mammal Foundation, San Diego, CA, USA
- *Correspondence: Dorian S. Houser, Department of Conservation and Biological Research, National Marine Mammal Foundation, 2240 Shelter Island Drive, Suite 200, San Diego, CA 92106, USA e-mail:
| | - Cory D. Champagne
- Department of Conservation and Biological Research, National Marine Mammal Foundation, San Diego, CA, USA
| | - Daniel E. Crocker
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA
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Verrier D, Groscolas R, Guinet C, Arnould JPY. Development of fasting abilities in subantarctic fur seal pups: balancing the demands of growth under extreme nutritional restrictions. Funct Ecol 2011. [DOI: 10.1111/j.1365-2435.2010.01823.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Richmond JP, Jeanniard du Dot T, Rosen DAS, Zinn SA. Seasonal influence on the response of the somatotropic axis to nutrient restriction and re-alimentation in captive Steller sea lions (Eumetopias jubatus). JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL GENETICS AND PHYSIOLOGY 2010; 313:144-56. [PMID: 20084663 DOI: 10.1002/jez.584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Fluctuations in availability of prey resources can impede acquisition of sufficient energy for maintenance and growth. By investigating the hormonal mechanisms of the somatotropic axis that link nutrition, fat metabolism, and lean tissue accretion, we can assess the physiological impact of decreased nutrient intake on growth. Further, species that undergo seasonal periods of reduced intake as a part of their normal life history may have a differential seasonal response to nutrient restriction. This experiment evaluated the influence of season and age on the response of the somatotropic axis, including growth hormone (GH), insulin-like growth factor (IGF)-I, and IGF-binding proteins (BP), to reduced nutrient intake and re-alimentation in Steller sea lions. Eight captive females (five juveniles, three sub-adults) were subject to 28-day periods of food restriction, controlled re-feeding, and ad libitum recovery in summer (long-day photoperiod) and winter (short-day photoperiod). Hormone concentrations were insensitive to type of fish fed (low fat pollock vs. high fat herring), but sensitive to energy intake. Body mass, fat, and IGF-I declined, whereas GH and IGFBP-2 increased during feed restriction. Reduced IGF-I and IGFBP with increased GH during controlled re-feeding suggest that animals did not reach positive energy balance until fed ad libitum. Increased IGF-I, IGFBP-2, IGFBP-3, and reduced GH observed in summer reflected seasonal differences in energy partitioning. There was a strong season and age effect in the response to restriction and re-alimentation, indicating that older, larger animals are better able to cope with stress associated with energy deficit, regardless of season.
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Affiliation(s)
- Julie P Richmond
- Department of Animal Science, University of Connecticut, Storrs, Connecticut, CT06269, USA.
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Noren DP, Rea LD, Loughlin TR. A model to predict fasting capacities and utilization of body energy stores in weaned Steller sea lions (Eumetopias jubatus) during periods of reduced prey availability. CAN J ZOOL 2009. [DOI: 10.1139/z09-074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The population decline of Steller sea lions ( Eumetopias jubatus (Schreber, 1776)) may be linked to a decline in juvenile survivorship. Limitations in prey availability may contribute to the decline, thus it is important to understand fasting capacities of Steller sea lions. For most mammals, fat catabolism is the preferred energetic pathway to ensure that protein is spared. However, marine mammals also have a conflicting requirement to conserve fat because the main site of fat storage is the blubber layer, which is also their primary thermal barrier when at sea. We developed a dynamic state variable model to demonstrate how protein and fat reserve utilization and maximum fasting duration are influenced by body condition and time spent foraging. This model was parameterized with respect to conditions faced by juvenile and subadult Steller sea lions foraging unsuccessfully during a period of reduced prey availability. The model accurately predicted changes in fat and protein mass of juvenile and subadult Steller sea lions fasting in captivity. Furthermore, the model demonstrated that body lipid content, body mass, and the proportion of time spent in water influence energy reserve catabolism and maximum fasting durations. Consequently, small, lean individuals are particularly susceptible to reductions in prey availability.
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Affiliation(s)
- D. P. Noren
- National Marine Mammal Laboratory, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center, 7600 Sand Point Way Northeast, Seattle, WA 98115, USA
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Northwest Fisheries Science Center, 2725 Montlake Boulevard East, Seattle, WA 98112, USA
- Department of Biology, University of Central Florida, 4000 Central Florida Boulevard, Orlando, FL 32816, USA
- Alaska Department of Fish and Game, Division of Wildlife Conservation, Marine Mammal Research Section, 245 O’Neill Building, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - L. D. Rea
- National Marine Mammal Laboratory, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center, 7600 Sand Point Way Northeast, Seattle, WA 98115, USA
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Northwest Fisheries Science Center, 2725 Montlake Boulevard East, Seattle, WA 98112, USA
- Department of Biology, University of Central Florida, 4000 Central Florida Boulevard, Orlando, FL 32816, USA
- Alaska Department of Fish and Game, Division of Wildlife Conservation, Marine Mammal Research Section, 245 O’Neill Building, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - T. R. Loughlin
- National Marine Mammal Laboratory, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center, 7600 Sand Point Way Northeast, Seattle, WA 98115, USA
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Northwest Fisheries Science Center, 2725 Montlake Boulevard East, Seattle, WA 98112, USA
- Department of Biology, University of Central Florida, 4000 Central Florida Boulevard, Orlando, FL 32816, USA
- Alaska Department of Fish and Game, Division of Wildlife Conservation, Marine Mammal Research Section, 245 O’Neill Building, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
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7
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ROSEN DAVIDAS. Steller sea lions
Eumetopias jubatus
and nutritional stress: evidence from captive studies. Mamm Rev 2009. [DOI: 10.1111/j.1365-2907.2009.00150.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- DAVID A. S. ROSEN
- Marine Mammal Research Unit, University of British Columbia, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada
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