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Michael S Davis - One of the best experts on this subject based on the ideXlab platform.

  • acylcarnitine profile in alaskan Sled Dogs during submaximal multiday exercise points out metabolic flexibility and liver role in energy metabolism
    PLOS ONE, 2021
    Co-Authors: Irene Tosi, Tatiana Art, Francois Boemer, D Votion, Michael S Davis
    Abstract:

    Alaskan Sled Dogs develop a particular metabolic strategy during multiday submaximal exercise, allowing them to switch from intra-muscular to extra-muscular energy substrates thus postponing fatigue. Specifically, a progressively increasing stimulus for hepatic glycogenolysis and gluconeogenesis provides glucose for both fueling exercise and replenishing the depleted muscle glycogen. Moreover, recent studies have shown that with continuation of exercise Sled Dogs increase their insulin-sensitivity and their capacity to transport and oxidize glucose and carbohydrates rather than oxidizing fatty acids. Carnitine and acylcarnitines (AC) play an essential role as metabolic regulators in both fat and glucose metabolism; they serve as biomarkers in different species in both physiologic and pathologic conditions. We assessed the effect of multiday exercise in conditioned Sled Dogs on plasma short (SC), medium (MC) and long (LC) chain AC by tandem mass spectrometry (MS/MS). Our results show chain-specific modification of AC profiles during the exercise challenge: LCACs maintained a steady increase throughout exercise, some SCACs increased during the last phase of exercise and acetylcarnitine (C2) initially increased before decreasing during the later phase of exercise. We speculated that SCACs kinetics could reflect an increased protein catabolism and C2 pattern could reflect its hepatic uptake for energy-generating purposes to sustain gluconeogenesis. LCACs may be exported by muscle to avoid their accumulation to preserve glucose oxidation and insulin-sensitivity or they could be distributed by liver as energy substrates. These findings, although representing a "snapshot" of blood as a crossing point between different organs, shed further light on Sled Dogs metabolism that is liver-centric and more carbohydrate-dependent than fat-dependent and during prolonged submaximal exercise.

  • glucocentric metabolism in ultra endurance Sled Dogs
    Integrative and Comparative Biology, 2021
    Co-Authors: Michael S Davis
    Abstract:

    The total energy expenditure of a racing Sled dog can exceed 500 kcal/kg bodyweight during typical events spanning a week or more. Based on early research, as well as practical considerations, modern commercial diets are formulated to meet these energy requirements using fat and protein. However, more recent research provides a clear picture of a canine athlete with glucocentric metabolism, including many conditioning-induced adaptations oriented towards sustaining submaximal exercise with glucose as the primary metabolic fuel despite the consumption of fat as the primary dietary energy source. The specific strategies used by racing Sled Dogs to maintain a robust supply of glucose during exercise, as well as the possible role of fat in facilitating that metabolic priority, is the subject of ongoing research.

  • orthopedic and ultrasonographic examination findings in 128 shoulders of 64 ultra endurance alaskan Sled Dogs
    Veterinary Surgery, 2021
    Co-Authors: Dirsko J F Von Pfeil, Michael S Davis, William D Liska, Clinton George, Scott Secrest
    Abstract:

    Objective To determine the location and periarticular shoulder-muscle-abnormalities detected via orthopedic examinations and ultrasonography in ultra-endurance Alaskan Sled-Dogs, returned from an ultra-endurance Sled-dog-race prior to finishing it. Study design Prospective clinical study. Sample population Sixty-four Dogs (128 shoulders). Methods Dogs were classified based on clinical evidence of shoulder pain (SP versus control). Orthopedic examination findings, shoulder-abduction-angles (SAA; before- and during-anesthesia), and ultrasonographic findings were recorded. Relationships between orthopedic and ultrasonographic abnormalities were compared. Results Pain was elicited on 55/128 shoulders; 73 shoulders were pain-free. The most common painful structures included the biceps-tendon (BT; 30%), triceps-muscle (28%), and infraspinatus-muscle (25%). SAA ranged between 25° and 75° among groups, including pain-free shoulders in Dogs without lameness. SAA was greater when Dogs were anesthetized (46.3° ± 14.0° vs. 47.8° ± 12.0°; p = .03), especially in SP (mean increase of 3.49° ± 8.85°) compared to control (0.03° ± 7.71°, p = .009). Overall, 103 ultrasonographic abnormalities were detected (SP: 44; control: 59). The most common ultrasonographic abnormality was fluid surrounding the biceps tendon, similarly distributed between groups (SP: 39/44; control: 57/59). Most chronic ultrasonographic abnormalities affected the BT (15/103 abnormalities). No associations were detected between ultrasonographic abnormalities and clinical findings. Conclusion Shoulder abduction varied greatly and reached up to 75° in normal joints. Ultrasonographic shoulder-muscle abnormalities were common but did not seem associated with clinical findings. Clinical significance Interpretation of shoulder abduction warrants caution, and the presence of fluid around the BT may reflect a physiologic adaptation to racing, rather than a pathologic change in ultra-endurance Alaskan Sled-Dogs.

  • serum metabolomics of alaskan Sled Dogs during endurance racing
    Comparative Exercise Physiology, 2018
    Co-Authors: Laurijo Gamble, Cristina M Hansen, Michael S Davis, C W Frye, Jason W Locasale, Xiaojing Liu, Joseph J. Wakshlag
    Abstract:

    Long distance racing Sled Dogs are fed diets high in fat since lipid metabolism has long been thought to be the major substrate utilised during endurance racing. However, recent studies suggests th...

  • Effect of pre-exercise massage on exercise-induced muscle injury in Sled Dogs
    Comparative Exercise Physiology, 2015
    Co-Authors: H.w. Huneycutt, Michael S Davis
    Abstract:

    Previous necropsy studies have shown that up to 60% of Sled Dogs competing in endurance Sled dog races have areas of muscle damage. Human athletes and trainers have maintained a strong belief, based mostly on personal experiences, that massage can be effective for pre-race preparation and expedited recovery between consecutive events. We proposed that massage could lessen the degree of creatine phosphokinase (CPK) release when utilised prior to endurance activities. A randomised crossover study was performed using minimally conditioned Sled Dogs from a Sled dog racing kennel. Each dog in the treatment group received a 14 min massage immediately prior to controlled endurance exercise. The pre-exercise CPK activity was 64±11 IU/l (mean ± standard deviation). The difference between pre-exercise CPK and post-exercise CPK for both groups was expressed as delta CPK. The delta CPK for the massage group was 62±22 IU/l and 74±55 IU/l for the control group. There was no significant change in concentration of CPK be...

Lawrence K Duffy - One of the best experts on this subject based on the ideXlab platform.

  • Sled Dogs as a model for pm2 5 exposure from wildfires in alaska
    Environment International, 2021
    Co-Authors: Jacob J Witkop, Arleigh J Reynolds, Lawrence K Duffy, Theresa Vertigan, Bahareh Barati, Scott P Jerome, Kriya L Dunlap
    Abstract:

    Abstract Particulate matter 2.5 (PM2.5) exposure induces oxidative stress associated with many negative health outcomes such as respiratory disorders, cardiovascular disease and neurodegenerative disease. Research shows that diet and exercise can improve antioxidant defense against oxidative stress. This study is the first to use an Arctic animal model to investigate the cumulative effects of two lifestyle interventions on the antioxidant response before, during, and after ambient PM 2.5 exposure from wildfire: antioxidant supplementation (Arthrospira platensis) and exercise. In a two-factorial, longitudinal design, this study divided Sled Dogs (n = 48) into four groups (exercise and supplemented, exercise, supplemented, and control) to (1) test the effects of a 30-day exercise and antioxidant supplementation protocol on antioxidant response; and (2) measure the antioxidant response of all groups during and after a natural wildfire event. Commercial assays for total antioxidant power (TAP) and the enzymatic antioxidant superoxide dismutase (SOD) were used as markers for antioxidant status and response. During the forest fire, SOD was increased 5- to 10-fold over pre/post-exposure levels in all groups suggesting an endogenous upregulation of defense systems in response to the acute environmental stress. TAP was lower in all groups at peak PM2.5 exposure compared to 48 h after peak exposure in all groups except the exercise alone group which may indicate that exercise offers improved endogenous defense.

  • the effect of acute exercise on glut4 levels in peripheral blood mononuclear cells of Sled Dogs
    Biochemistry and biophysics reports, 2015
    Co-Authors: Theresia M. Schnurr, Arleigh J Reynolds, Lawrence K Duffy, Alyssa M Komac, Kriya L Dunlap
    Abstract:

    Using Sled Dogs as exercise model, our objectives of this study were to 1) assess the effects of one acute bout of high-intensity exercise on surface GLUT4 concentrations on easily accessible peripheral blood mononuclear cells (PBMC) and 2) compare our findings with published research on exercise induced GLUT4 in skeletal muscle. During the exercise bout, Dogs ran 5 miles at approximately 90% of VO2 max. PMBC were collected before exercise (baseline), immediately after exercise and after 24h recovery.GLUT4 was measured via ELISA. Acute exercise resulted in a significant increase on surface GLUT4 content on PBMC. GLUT4 was increased significantly immediately after exercise (~ 50%; p 0.05). An effect of acute exercise on GLUT4 levels translocated to the cell membrane was observed, with GLUT4 levels not yet returned to baseline after 24h post-exercise. In conclusion, the present investigation demonstrated that acute high-intensity exercise increased GLUT4 content at the surface of PBMC of Sled Dogs as it has been reported in skeletal muscle in other species. Our findings underline the potential use of peripheral blood mononuclear cell GLUT4 protein content as minimally invasive proxy to investigate relationships between insulin sensitivity, insulin resistance, GLUT4 expression and glucose metabolism.

  • glucose transporter 4 in white blood cells of young and old Sled Dogs a model for human biomarker development
    Polar Record, 2015
    Co-Authors: Theresia M. Schnurr, Arleigh J Reynolds, Lawrence K Duffy, Kriya L Dunlap
    Abstract:

    The insulin responsive glucose transporter, GLUT4 is found predominantly in muscle and adipose cells. Maratou and others (2007) reported that there is GLUT4 in white blood cells (WBC) collected from human subjects in response to insulin activation. This study was designed to validate the presence of GLUT4 in white blood cells of Sled Dogs and furthermore to investigate whether changes in levels of the GLUT4 protein might be associated with aging. Additionally, we examined the blood insulin concentration of two populations of Dogs, young and old, before and after a meal to observe their insulin response. It is documented in skeletal muscle that GLUT4 expression is increased as a result of conditioning, making Sled Dogs an excellent model in the circumpolar north for studying the effects of exercise, nutrition and diabetes (Felsburg 2002; Kararli 2006). Blood was withdrawn from 11 healthy Sled Dogs: 6 young (1-5 years) and physically fit, conditioned for racing and 5 old (7-13 years), retired from racing. The insulin response was determined using blood plasma and ELISA. The buffy coat (containing WBC) was collected with a glass pipette after centrifugation and washed and suspended in 1x phosphate buffer. GLUT4 was measured using ELISA kits (USCN Life Sciences). The results validate that GLUT4 is present in white blood cells in Sled Dogs. Age had no significant effect in the concentration of GLUT4 between the populations of old and young Dogs. A significant difference in insulin levels pre and post meal in young (0.13 ± 0.03 ng/mL (pre), 0.22 ± 0.04 ng/mL (post), p 0.05). Detecting GLUT4 via an ELISA in white blood cells, opens up minimally invasive avenues for studying the underlying molecular mechanisms associated with insulin resistance in more complex, dynamic and physiological systems. This project was the first step in developing a protocol for this simple, technique with a potential clinical application for diagnosing insulin resistance.

  • Conditioning causes an increase in glucose transporter-4 levels in mononuclear cells in Sled Dogs.
    The international journal of biochemistry & cell biology, 2014
    Co-Authors: Theresia M. Schnurr, Arleigh J Reynolds, Lawrence K Duffy, Sally J. Gustafson, Kriya L Dunlap
    Abstract:

    Abstract This study was designed to investigate the effects of physical conditioning on the expression of the insulin sensitive glucose transporter-4 protein (GLUT4) on mononuclear cells and HOMA-IR levels in Dogs and compared to results reported in human skeletal muscle and the skeletal muscle of rodent models. Blood was sampled from conditioned Dogs (n = 8) and sedentary Dogs (n = 8). The conditioned Dogs were exercised four months prior the experiment and were following a uniform training protocol, whereas the sedentary Dogs were not. GLUT4 expression in mononuclear cells and plasma insulin levels were measured using commercially available enzyme-linked immunosorbent assay (ELISA). Blood glucose levels were determined using blood plasma. HOMA-IR was calculated using plasma insulin and blood glucose levels using the linear approximation formula. Our results indicate that the state of conditioning had a significant effect on the GLUT4 expression at the surface of mononuclear cells. HOMA-IR was also affected by conditioning in Dogs. GLUT4 levels in mononuclear cells of Sled Dogs were inversely correlated with the homeostasis model assessment of insulin sensitivity. This study demonstrates that conditioning increases GLUT4 levels in mononuclear cells of Sled Dogs as it has been previously reported in skeletal muscle. Our results support the potential of white blood cells as a proxy tissue for studying insulin signaling and may lead to development of a minimally invasive and direct marker of insulin resistance. This may be the first report of GLUT4 in mononuclear cells in response to exercise and measured with ELISA.

  • selected plasma fatty acid levels in subsistence fed Sled Dogs along the yukon river a pilot study for biomonitoring
    Polar Record, 2012
    Co-Authors: Kriya L Dunlap, Arleigh J Reynolds, Lawrence K Duffy, Craig S Gerlach, Philip A Loring, Marilyn Cleroux, Jeanphilippe Godin
    Abstract:

    The introduction of the ‘western diet’ marked a decline in omega–3 fatty acids rich foods and a concurrent increase in saturated and omega–6 fatty acids that persists today. Historically, circumpolar people have had a low incidence of obesity, diabetes and cardiovascular disease and this has been largely attributed to polyphenolic compounds and omega–3 fatty acids offered from subsistence foods. In this report, we studied Sled Dogs as an Arctic sentinel species for monitoring the effect of a changing diet on lipid profiles along the Yukon River. Subsistence fed village Sled Dogs along the Yukon River, maintained largely on salmon were compared with a control kennel maintained on commercial food. Profiles showed higher levels for long chain omega–3 fatty acids in village subsistence fed Dogs compared to control Dogs and an opposite trend for omega–6 fatty acids, establishing baseline levels for follow up studies. A comparison with data for previously published mercury levels from the same cohort of Dogs revealed a positive correlation with alpha–linolenic fatty acid and a negative correlation with linoleic fatty acid. Food and nutritional security is a concern in the Arctic as the impacts of climate change and transport of contaminants become obvious. This study supports not only the nutritional value of a subsistence diet but also the utility of Sled Dogs as a sentinel for human dietary change.

Kriya L Dunlap - One of the best experts on this subject based on the ideXlab platform.

  • Sled Dogs as a model for pm2 5 exposure from wildfires in alaska
    Environment International, 2021
    Co-Authors: Jacob J Witkop, Arleigh J Reynolds, Lawrence K Duffy, Theresa Vertigan, Bahareh Barati, Scott P Jerome, Kriya L Dunlap
    Abstract:

    Abstract Particulate matter 2.5 (PM2.5) exposure induces oxidative stress associated with many negative health outcomes such as respiratory disorders, cardiovascular disease and neurodegenerative disease. Research shows that diet and exercise can improve antioxidant defense against oxidative stress. This study is the first to use an Arctic animal model to investigate the cumulative effects of two lifestyle interventions on the antioxidant response before, during, and after ambient PM 2.5 exposure from wildfire: antioxidant supplementation (Arthrospira platensis) and exercise. In a two-factorial, longitudinal design, this study divided Sled Dogs (n = 48) into four groups (exercise and supplemented, exercise, supplemented, and control) to (1) test the effects of a 30-day exercise and antioxidant supplementation protocol on antioxidant response; and (2) measure the antioxidant response of all groups during and after a natural wildfire event. Commercial assays for total antioxidant power (TAP) and the enzymatic antioxidant superoxide dismutase (SOD) were used as markers for antioxidant status and response. During the forest fire, SOD was increased 5- to 10-fold over pre/post-exposure levels in all groups suggesting an endogenous upregulation of defense systems in response to the acute environmental stress. TAP was lower in all groups at peak PM2.5 exposure compared to 48 h after peak exposure in all groups except the exercise alone group which may indicate that exercise offers improved endogenous defense.

  • the effect of acute exercise on glut4 levels in peripheral blood mononuclear cells of Sled Dogs
    Biochemistry and biophysics reports, 2015
    Co-Authors: Theresia M. Schnurr, Arleigh J Reynolds, Lawrence K Duffy, Alyssa M Komac, Kriya L Dunlap
    Abstract:

    Using Sled Dogs as exercise model, our objectives of this study were to 1) assess the effects of one acute bout of high-intensity exercise on surface GLUT4 concentrations on easily accessible peripheral blood mononuclear cells (PBMC) and 2) compare our findings with published research on exercise induced GLUT4 in skeletal muscle. During the exercise bout, Dogs ran 5 miles at approximately 90% of VO2 max. PMBC were collected before exercise (baseline), immediately after exercise and after 24h recovery.GLUT4 was measured via ELISA. Acute exercise resulted in a significant increase on surface GLUT4 content on PBMC. GLUT4 was increased significantly immediately after exercise (~ 50%; p 0.05). An effect of acute exercise on GLUT4 levels translocated to the cell membrane was observed, with GLUT4 levels not yet returned to baseline after 24h post-exercise. In conclusion, the present investigation demonstrated that acute high-intensity exercise increased GLUT4 content at the surface of PBMC of Sled Dogs as it has been reported in skeletal muscle in other species. Our findings underline the potential use of peripheral blood mononuclear cell GLUT4 protein content as minimally invasive proxy to investigate relationships between insulin sensitivity, insulin resistance, GLUT4 expression and glucose metabolism.

  • glucose transporter 4 in white blood cells of young and old Sled Dogs a model for human biomarker development
    Polar Record, 2015
    Co-Authors: Theresia M. Schnurr, Arleigh J Reynolds, Lawrence K Duffy, Kriya L Dunlap
    Abstract:

    The insulin responsive glucose transporter, GLUT4 is found predominantly in muscle and adipose cells. Maratou and others (2007) reported that there is GLUT4 in white blood cells (WBC) collected from human subjects in response to insulin activation. This study was designed to validate the presence of GLUT4 in white blood cells of Sled Dogs and furthermore to investigate whether changes in levels of the GLUT4 protein might be associated with aging. Additionally, we examined the blood insulin concentration of two populations of Dogs, young and old, before and after a meal to observe their insulin response. It is documented in skeletal muscle that GLUT4 expression is increased as a result of conditioning, making Sled Dogs an excellent model in the circumpolar north for studying the effects of exercise, nutrition and diabetes (Felsburg 2002; Kararli 2006). Blood was withdrawn from 11 healthy Sled Dogs: 6 young (1-5 years) and physically fit, conditioned for racing and 5 old (7-13 years), retired from racing. The insulin response was determined using blood plasma and ELISA. The buffy coat (containing WBC) was collected with a glass pipette after centrifugation and washed and suspended in 1x phosphate buffer. GLUT4 was measured using ELISA kits (USCN Life Sciences). The results validate that GLUT4 is present in white blood cells in Sled Dogs. Age had no significant effect in the concentration of GLUT4 between the populations of old and young Dogs. A significant difference in insulin levels pre and post meal in young (0.13 ± 0.03 ng/mL (pre), 0.22 ± 0.04 ng/mL (post), p 0.05). Detecting GLUT4 via an ELISA in white blood cells, opens up minimally invasive avenues for studying the underlying molecular mechanisms associated with insulin resistance in more complex, dynamic and physiological systems. This project was the first step in developing a protocol for this simple, technique with a potential clinical application for diagnosing insulin resistance.

  • Conditioning causes an increase in glucose transporter-4 levels in mononuclear cells in Sled Dogs.
    The international journal of biochemistry & cell biology, 2014
    Co-Authors: Theresia M. Schnurr, Arleigh J Reynolds, Lawrence K Duffy, Sally J. Gustafson, Kriya L Dunlap
    Abstract:

    Abstract This study was designed to investigate the effects of physical conditioning on the expression of the insulin sensitive glucose transporter-4 protein (GLUT4) on mononuclear cells and HOMA-IR levels in Dogs and compared to results reported in human skeletal muscle and the skeletal muscle of rodent models. Blood was sampled from conditioned Dogs (n = 8) and sedentary Dogs (n = 8). The conditioned Dogs were exercised four months prior the experiment and were following a uniform training protocol, whereas the sedentary Dogs were not. GLUT4 expression in mononuclear cells and plasma insulin levels were measured using commercially available enzyme-linked immunosorbent assay (ELISA). Blood glucose levels were determined using blood plasma. HOMA-IR was calculated using plasma insulin and blood glucose levels using the linear approximation formula. Our results indicate that the state of conditioning had a significant effect on the GLUT4 expression at the surface of mononuclear cells. HOMA-IR was also affected by conditioning in Dogs. GLUT4 levels in mononuclear cells of Sled Dogs were inversely correlated with the homeostasis model assessment of insulin sensitivity. This study demonstrates that conditioning increases GLUT4 levels in mononuclear cells of Sled Dogs as it has been previously reported in skeletal muscle. Our results support the potential of white blood cells as a proxy tissue for studying insulin signaling and may lead to development of a minimally invasive and direct marker of insulin resistance. This may be the first report of GLUT4 in mononuclear cells in response to exercise and measured with ELISA.

  • selected plasma fatty acid levels in subsistence fed Sled Dogs along the yukon river a pilot study for biomonitoring
    Polar Record, 2012
    Co-Authors: Kriya L Dunlap, Arleigh J Reynolds, Lawrence K Duffy, Craig S Gerlach, Philip A Loring, Marilyn Cleroux, Jeanphilippe Godin
    Abstract:

    The introduction of the ‘western diet’ marked a decline in omega–3 fatty acids rich foods and a concurrent increase in saturated and omega–6 fatty acids that persists today. Historically, circumpolar people have had a low incidence of obesity, diabetes and cardiovascular disease and this has been largely attributed to polyphenolic compounds and omega–3 fatty acids offered from subsistence foods. In this report, we studied Sled Dogs as an Arctic sentinel species for monitoring the effect of a changing diet on lipid profiles along the Yukon River. Subsistence fed village Sled Dogs along the Yukon River, maintained largely on salmon were compared with a control kennel maintained on commercial food. Profiles showed higher levels for long chain omega–3 fatty acids in village subsistence fed Dogs compared to control Dogs and an opposite trend for omega–6 fatty acids, establishing baseline levels for follow up studies. A comparison with data for previously published mercury levels from the same cohort of Dogs revealed a positive correlation with alpha–linolenic fatty acid and a negative correlation with linoleic fatty acid. Food and nutritional security is a concern in the Arctic as the impacts of climate change and transport of contaminants become obvious. This study supports not only the nutritional value of a subsistence diet but also the utility of Sled Dogs as a sentinel for human dietary change.

Arleigh J Reynolds - One of the best experts on this subject based on the ideXlab platform.

  • Sled Dogs as a model for pm2 5 exposure from wildfires in alaska
    Environment International, 2021
    Co-Authors: Jacob J Witkop, Arleigh J Reynolds, Lawrence K Duffy, Theresa Vertigan, Bahareh Barati, Scott P Jerome, Kriya L Dunlap
    Abstract:

    Abstract Particulate matter 2.5 (PM2.5) exposure induces oxidative stress associated with many negative health outcomes such as respiratory disorders, cardiovascular disease and neurodegenerative disease. Research shows that diet and exercise can improve antioxidant defense against oxidative stress. This study is the first to use an Arctic animal model to investigate the cumulative effects of two lifestyle interventions on the antioxidant response before, during, and after ambient PM 2.5 exposure from wildfire: antioxidant supplementation (Arthrospira platensis) and exercise. In a two-factorial, longitudinal design, this study divided Sled Dogs (n = 48) into four groups (exercise and supplemented, exercise, supplemented, and control) to (1) test the effects of a 30-day exercise and antioxidant supplementation protocol on antioxidant response; and (2) measure the antioxidant response of all groups during and after a natural wildfire event. Commercial assays for total antioxidant power (TAP) and the enzymatic antioxidant superoxide dismutase (SOD) were used as markers for antioxidant status and response. During the forest fire, SOD was increased 5- to 10-fold over pre/post-exposure levels in all groups suggesting an endogenous upregulation of defense systems in response to the acute environmental stress. TAP was lower in all groups at peak PM2.5 exposure compared to 48 h after peak exposure in all groups except the exercise alone group which may indicate that exercise offers improved endogenous defense.

  • the effect of acute exercise on glut4 levels in peripheral blood mononuclear cells of Sled Dogs
    Biochemistry and biophysics reports, 2015
    Co-Authors: Theresia M. Schnurr, Arleigh J Reynolds, Lawrence K Duffy, Alyssa M Komac, Kriya L Dunlap
    Abstract:

    Using Sled Dogs as exercise model, our objectives of this study were to 1) assess the effects of one acute bout of high-intensity exercise on surface GLUT4 concentrations on easily accessible peripheral blood mononuclear cells (PBMC) and 2) compare our findings with published research on exercise induced GLUT4 in skeletal muscle. During the exercise bout, Dogs ran 5 miles at approximately 90% of VO2 max. PMBC were collected before exercise (baseline), immediately after exercise and after 24h recovery.GLUT4 was measured via ELISA. Acute exercise resulted in a significant increase on surface GLUT4 content on PBMC. GLUT4 was increased significantly immediately after exercise (~ 50%; p 0.05). An effect of acute exercise on GLUT4 levels translocated to the cell membrane was observed, with GLUT4 levels not yet returned to baseline after 24h post-exercise. In conclusion, the present investigation demonstrated that acute high-intensity exercise increased GLUT4 content at the surface of PBMC of Sled Dogs as it has been reported in skeletal muscle in other species. Our findings underline the potential use of peripheral blood mononuclear cell GLUT4 protein content as minimally invasive proxy to investigate relationships between insulin sensitivity, insulin resistance, GLUT4 expression and glucose metabolism.

  • glucose transporter 4 in white blood cells of young and old Sled Dogs a model for human biomarker development
    Polar Record, 2015
    Co-Authors: Theresia M. Schnurr, Arleigh J Reynolds, Lawrence K Duffy, Kriya L Dunlap
    Abstract:

    The insulin responsive glucose transporter, GLUT4 is found predominantly in muscle and adipose cells. Maratou and others (2007) reported that there is GLUT4 in white blood cells (WBC) collected from human subjects in response to insulin activation. This study was designed to validate the presence of GLUT4 in white blood cells of Sled Dogs and furthermore to investigate whether changes in levels of the GLUT4 protein might be associated with aging. Additionally, we examined the blood insulin concentration of two populations of Dogs, young and old, before and after a meal to observe their insulin response. It is documented in skeletal muscle that GLUT4 expression is increased as a result of conditioning, making Sled Dogs an excellent model in the circumpolar north for studying the effects of exercise, nutrition and diabetes (Felsburg 2002; Kararli 2006). Blood was withdrawn from 11 healthy Sled Dogs: 6 young (1-5 years) and physically fit, conditioned for racing and 5 old (7-13 years), retired from racing. The insulin response was determined using blood plasma and ELISA. The buffy coat (containing WBC) was collected with a glass pipette after centrifugation and washed and suspended in 1x phosphate buffer. GLUT4 was measured using ELISA kits (USCN Life Sciences). The results validate that GLUT4 is present in white blood cells in Sled Dogs. Age had no significant effect in the concentration of GLUT4 between the populations of old and young Dogs. A significant difference in insulin levels pre and post meal in young (0.13 ± 0.03 ng/mL (pre), 0.22 ± 0.04 ng/mL (post), p 0.05). Detecting GLUT4 via an ELISA in white blood cells, opens up minimally invasive avenues for studying the underlying molecular mechanisms associated with insulin resistance in more complex, dynamic and physiological systems. This project was the first step in developing a protocol for this simple, technique with a potential clinical application for diagnosing insulin resistance.

  • Conditioning causes an increase in glucose transporter-4 levels in mononuclear cells in Sled Dogs.
    The international journal of biochemistry & cell biology, 2014
    Co-Authors: Theresia M. Schnurr, Arleigh J Reynolds, Lawrence K Duffy, Sally J. Gustafson, Kriya L Dunlap
    Abstract:

    Abstract This study was designed to investigate the effects of physical conditioning on the expression of the insulin sensitive glucose transporter-4 protein (GLUT4) on mononuclear cells and HOMA-IR levels in Dogs and compared to results reported in human skeletal muscle and the skeletal muscle of rodent models. Blood was sampled from conditioned Dogs (n = 8) and sedentary Dogs (n = 8). The conditioned Dogs were exercised four months prior the experiment and were following a uniform training protocol, whereas the sedentary Dogs were not. GLUT4 expression in mononuclear cells and plasma insulin levels were measured using commercially available enzyme-linked immunosorbent assay (ELISA). Blood glucose levels were determined using blood plasma. HOMA-IR was calculated using plasma insulin and blood glucose levels using the linear approximation formula. Our results indicate that the state of conditioning had a significant effect on the GLUT4 expression at the surface of mononuclear cells. HOMA-IR was also affected by conditioning in Dogs. GLUT4 levels in mononuclear cells of Sled Dogs were inversely correlated with the homeostasis model assessment of insulin sensitivity. This study demonstrates that conditioning increases GLUT4 levels in mononuclear cells of Sled Dogs as it has been previously reported in skeletal muscle. Our results support the potential of white blood cells as a proxy tissue for studying insulin signaling and may lead to development of a minimally invasive and direct marker of insulin resistance. This may be the first report of GLUT4 in mononuclear cells in response to exercise and measured with ELISA.

  • selected plasma fatty acid levels in subsistence fed Sled Dogs along the yukon river a pilot study for biomonitoring
    Polar Record, 2012
    Co-Authors: Kriya L Dunlap, Arleigh J Reynolds, Lawrence K Duffy, Craig S Gerlach, Philip A Loring, Marilyn Cleroux, Jeanphilippe Godin
    Abstract:

    The introduction of the ‘western diet’ marked a decline in omega–3 fatty acids rich foods and a concurrent increase in saturated and omega–6 fatty acids that persists today. Historically, circumpolar people have had a low incidence of obesity, diabetes and cardiovascular disease and this has been largely attributed to polyphenolic compounds and omega–3 fatty acids offered from subsistence foods. In this report, we studied Sled Dogs as an Arctic sentinel species for monitoring the effect of a changing diet on lipid profiles along the Yukon River. Subsistence fed village Sled Dogs along the Yukon River, maintained largely on salmon were compared with a control kennel maintained on commercial food. Profiles showed higher levels for long chain omega–3 fatty acids in village subsistence fed Dogs compared to control Dogs and an opposite trend for omega–6 fatty acids, establishing baseline levels for follow up studies. A comparison with data for previously published mercury levels from the same cohort of Dogs revealed a positive correlation with alpha–linolenic fatty acid and a negative correlation with linoleic fatty acid. Food and nutritional security is a concern in the Arctic as the impacts of climate change and transport of contaminants become obvious. This study supports not only the nutritional value of a subsistence diet but also the utility of Sled Dogs as a sentinel for human dietary change.

K W Hinchcliff - One of the best experts on this subject based on the ideXlab platform.

  • participation in a 1 000 mile race increases the oxidation of carbohydrate in alaskan Sled Dogs
    Journal of Applied Physiology, 2015
    Co-Authors: Benjamin F Miller, Michael S Davis, K W Hinchcliff, Joshua C Drake, Frederick F Peelor, Laurie M Biela, R J Geor, Karyn L Hamilton
    Abstract:

    The Alaskan Husky has been specifically bred for endurance performance and is capable of extreme endurance performance. We examined Sled Dogs in the trained state at the beginning of the race seaso...

  • hypogammaglobulinemia in racing alaskan Sled Dogs
    Journal of Veterinary Internal Medicine, 2010
    Co-Authors: Erica C. Mckenzie, Michael S Davis, Mark E Payton, K W Hinchcliff, Christopher Lupfer, Heidi E Banse, S Love, Steven E Nelson, Manoj K Pastey
    Abstract:

    Background: Serum immunoglobulin dynamics have not been studied in racing Sled Dogs, despite hypoglobulinemia having been reported during racing events. Hypothesis/Objectives: Hypoglobulinemia in racing Sled Dogs is associated with decreases in serum IgA, IgE, IgG, and IgM concentrations during prolonged exercise. Animals: One hundred and fifty-seven Alaskan Sled Dogs that successfully completed a 1,000 mile race. Methods: Serum was obtained from 118 Sled Dogs within 1 month before the race and within 12 hours after completing the race. Serum also was obtained after 4 months of rest from 51 Dogs that successfully completed the race, including 12 previously sampled Dogs. Serum total protein ([TP]), albumin, and globulin ([Gl]) were measured, and serum IgA, IgE, IgG, and IgM were quantified by ELISA. Results: The proportion of Dogs with [Gl] ≤ 2.2 g/dL was significantly greater immediately after racing (38 of 118 Dogs, 32.2%) than before racing (21 of 118 Dogs, 17.8%, P= .005). Four months after racing, [Gl] was ≤ 2.2 g/dL in 23.5% (12 of 51) of Dogs. [IgG] was significantly lower before (8.21 ± 4.95 mg/mL) and immediately after (7.97 ± 5.62) racing compared with 4 months after racing (18.88 ± 5.76). Serum [IgM] and [IgE] were higher and [IgA] was lower before racing compared with immediately after racing. Conclusions and Clinical Importance: Sled Dogs participating in long-distance racing have substantial decreases in [IgG] in addition to decreases in [IgM] and [IgE]. The pronounced hypogammaglobulinemia observed in a large proportion of racing Sled Dogs might predispose them to infectious disease.

  • temporal pattern of skeletal muscle gene expression following endurance exercise in alaskan Sled Dogs
    Journal of Applied Physiology, 2009
    Co-Authors: Eric P Brass, K W Hinchcliff, Mette A Peters, Roger G Ulrich
    Abstract:

    Muscle responses to exercise are complex and include acute responses to exercise-induced injury, as well as longer term adaptive training responses. Using Alaskan Sled Dogs as an experimental model, changes in muscle gene expression were analyzed to test the hypotheses that important regulatory elements of the muscle's adaptation to exercise could be identified based on the temporal pattern of gene expression. Dogs were randomly assigned to undertake a 160-km run (n = 9), or to remain at rest (n = 4). Biceps femoris muscle was obtained from the unexercised Dogs and two Dogs at each of 2, 6, and 12 h after the exercise, and from three Dogs 24 h after exercise. RNA was extracted and microarray analysis used to define gene transcriptional changes. The changes in gene expression after exercise occurred in a temporal pattern. Overall, 569, 469, 316, and 223 transcripts were differentially expressed at 2, 6, 12, and 24 h postexercise, respectively, compared with unexercised Dogs (based on P ≤ 0.01 and an absolu...

  • assessment of alterations in triglyceride and glycogen concentrations in muscle tissue of alaskan Sled Dogs during repetitive prolonged exercise
    American Journal of Veterinary Research, 2008
    Co-Authors: Erica C. Mckenzie, Katherine K Williamson, Mark E Payton, K W Hinchcliff, Stephanie J Valberg, Michael S Davis
    Abstract:

    Objective—To assess changes in muscle glycogen (MG) and triglyceride (MT) concentrations in aerobically conditioned Sled Dogs during prolonged exercise. Animals—54 Alaskan Sled Dogs fed a high-fat diet. Procedures—48 Dogs ran 140-km distances on 4 consecutive days (cumulative distance, up to 560 km); 6 Dogs remained as nonexercising control animals. Muscle biopsies were performed immediately after running 140, 420, or 560 km (6 Dogs each) and subsequently after feeding and 7 hours of rest. Single muscle biopsies were performed during recovery at 28 hours in 7 Dogs that completed 560 km and at 50 and 98 hours in 7 and 6 Dogs that completed 510 km, respectively. Tissue samples were analyzed for MG and MT concentrations. Results—In control Dogs, mean ± SD MG and MT concentrations were 375 ± 37 mmol/kg of dry weight (kgDW) and 25.9 ± 10.3 mmol/kgDW, respectively. Compared with control values, MG concentration was lower after Dogs completed 140 and 420 km (137 ± 36 mmol/kgDW and 203 ± 30 mmol/kgDW, respectivel...

  • assessment of serum antibody titers against canine distemper virus canine adenovirus type ii and canine parvovirus in alaskan Sled Dogs before and after a long distance race
    Javma-journal of The American Veterinary Medical Association, 2008
    Co-Authors: Heidi E Banse, Stuart Nelson, Erica C. Mckenzie, K W Hinchcliff
    Abstract:

    Objective—To determine serum antibody titers against canine distemper virus (CDV), canine adenovirus type II (CAV-2), and canine parvovirus (CPV) in trained Sled Dogs prior to and after completion of a long-distance race. Design—Prospective cohort study. Animals—195 Alaskan Sled Dogs (from 18 kennels) that participated in the 2006 Iditarod Trail Race. Procedures—All 1,323 Dogs participating in the race had been vaccinated against the 3 viruses at 19 to 286 days prior to initial blood sample collection (obtained within the month preceding the race). Within 12 hours of race completion, blood samples were collected from 195 Dogs (convenience sample) and matched with each dog's prerace sample. Serum antibody titers (90% confidence intervals [CIs]) were determined via serum neutralization assays. Results—After racing, geometric mean titers against CDV and CPV were significantly higher (2,495 [90% CI, 321 to 16,384] and 6,323 [90% CI, 512 to 32,768], respectively) than prerace values (82 [90% CI, 11 to 362] and...