Teresa Davis | Baylor College of Medicine (original) (raw)
Papers by Teresa Davis
The FASEB Journal, Apr 1, 2013
Orogastric tube feeding is recommended in neonates unable to ingest food normally, and can be adm... more Orogastric tube feeding is recommended in neonates unable to ingest food normally, and can be administered by intermittent bolus (INT) or continuous (CON) infusion. Recently, we showed that INT compared to CON feeding enhances lean tissue accretion by increasing muscle protein synthesis in neonates. To determine the mechanism for this response, neonatal pigs (n=6, 6‐d‐old) were fed the same diet in equivalent amounts continuously or intermittently (meal every 4h) for 21d. Insulin receptor and insulin receptor substrate 1 expression and protein kinase B phosphorylation in skeletal muscle were unaffected by feeding modality. Formation of the active eukaryotic initiation factor (eIF) 4E‐eIF4G complex and phosphorylation of ribosomal protein S6 kinase were higher and phosphorylation of eIF2α was lower in INT compared to CON fed pigs indicating increased translation initiation (P<0.05). Sodium‐coupled neutral amino acid transporter 2, but not L‐type amino acid transporter 1, expression was higher in INT compared to CON pigs suggesting enhanced glutamine transport (P<0.05). Abundance of the ubiquitin ligases, muscle RING finger‐1 and F‐box protein atrogin‐1/MAFbx, was higher for INT compared to CON pigs (P<0.05). These results suggest that intermittent feeding enhances lean tissue accretion by increasing amino acid transport and protein turnover. (Supported by NIH AR444474 and USDA/ARS 6250–51000‐055)
Energy and protein metabolism and nutrition. 3rd EAAP International Symposium on Energy and Protein Metabolism and Nutrition, Parma, Italy, 6-10 September, 2010, 2010
Energy and protein metabolism and nutrition. 3rd EAAP International Symposium on Energy and Protein Metabolism and Nutrition, Parma, Italy, 6-10 September, 2010., 2010
The FASEB Journal, Apr 1, 2012
The FASEB Journal, Apr 1, 2011
Advances in Nutrition, 2016
Additional resources on what your abstract will be scored on and how to present can be found on t... more Additional resources on what your abstract will be scored on and how to present can be found on this page as well as on the ASN website. Make sure to choose an abstract category from the drop down list, pictured to the left.
Wageningen Academic Publishers eBooks, 2013
Orogastric tube feeding is indicated in neonates with impaired ability to ingest food normally an... more Orogastric tube feeding is indicated in neonates with impaired ability to ingest food normally and can be administered by intermittent bolus (INT) or continuous (CON) infusion. Insulin and amino acids play important roles in the regulation of protein synthesis in the neonate. While the sensitivity to insulin is developmentally regulated (Davis et al., 1998) and greatly diminishes with age (Wray-Cahen et al., 1997), amino acids exert a positive effect on muscle protein synthesis throughout life (Denne et al., 1991; Davis et al., 1998; Volpi et al., 1998). In addition to providing amino acids to other organs when dietary supplies are insufficient, high rates of proteolysis are necessary to provide amino acids for ongoing tissue modeling and rapid growth. The two most important proteolytic pathways in skeletal muscle are thought to be the ubiquitin-proteasome and autophagy-lysosome systems (Ventadour and Attaix, 2006). The aim of this study was to determine if these feeding modalities affect growth and lean tissue accretion, and the mechanisms for this response.
The FASEB Journal, Apr 1, 2007
Journal of Parenteral and Enteral Nutrition, Oct 10, 2022
Current developments in nutrition, Jun 1, 2022
Journal of Animal Science, Oct 8, 2021
Continuous feeding does not elicit an optimal anabolic response but is required for some prematur... more Continuous feeding does not elicit an optimal anabolic response but is required for some premature infants. We reported previously that intermittent intravenous pulses of Leu (800 μmol Leu·kg-1·h-1 every 4 h) to continuously fed pigs born at term enhanced skeletal muscle mTOR signaling and protein synthesis (PS). The objective of this study was to determine if the anabolic response of skeletal muscle to intermittent Leu pulses is altered following premature birth. Pigs delivered 10 d preterm by cesarean section were advanced to full oral feeding over four days (195 kcal·kg-1·d-1; 13.5 g protein·kg-1·d-1). Pigs were assigned to 1 of 4 treatments: 1) ALA (continuous feeding; 800 μmol Ala·kg-1·h-1 every 4 h; n = 7); 2) L1× (continuous feeding; 800 μmol Leu·kg-1·h-1 every 4 h; n = 6); 3) L2× (continuous feeding; 1600 μmol Leu·kg-1·h-1 every 4 h; n = 6); and 4) INT (intermittent feeding every 4 h; n = 5). Pigs received a Phe tracer 30 min following the amino acid pulse or intermittent feeding to measure PS in longissimus dorsi muscle. Anabolic signaling downstream of mTOR was determined by immunoblot.ResultsPS was higher in L2× and INT compared to ALA (P < 0.05) but was not different between L2× and INT; PS in L1× was intermediate and not different from other groups. Phosphorylation of 4EBP1 and S6K1 was higher in INT compared to L1× and ALA groups (P < 0.05) but was not different compared to L2×. Phosphorylation of 4EBP1, but not S6K1, was higher in L2× compared to ALA (P < 0.05); phosphorylation of 4EBP1 and S6K1 was not different between L1× and L2×.ConclusionsThese results demonstrate that intravenous Leu enhances mTOR activation and PS in LD muscle of continuously fed preterm pigs. However, the amount required may be higher than in pigs born at term.Source of Research SupportNIH and USDA.
The FASEB Journal, Apr 1, 2016
When neonatal pigs continuously fed formula are supplemented with leucine pulses, muscle protein ... more When neonatal pigs continuously fed formula are supplemented with leucine pulses, muscle protein synthesis and body weight gain are enhanced. To identify the responsible mechanisms, we combined plasma metabolomic analysis with transcriptome expression of the transcriptome and protein catabolic pathways in skeletal muscle. Piglets (n = 23, 7-day-old) were fed continuously a milk replacement formula via orogastric tube for 21 days with an additional parenteral infusion (800 μmol kg −1 h −1) of either leucine (LEU) or alanine (CON) for 1 h every 4 h. Plasma metabolites were measured by liquid chromatography-mass spectrometry. Gene and protein expression analyses of longissimus dorsi muscle were performed by RNA-seq and Western blot, ✉
Journal of Animal Science, Nov 3, 2020
Postnatal growth failure reduces lean mass accretion and increases adiposity. Previously we showe... more Postnatal growth failure reduces lean mass accretion and increases adiposity. Previously we showed that preterm birth impairs the feeding-induced stimulation of mechanistic target of rapamycin (mTOR), translation initiation, and protein synthesis in skeletal muscle of neonatal pigs. Considering that pig body weight can vary widely at birth, we wished to differentiate the effect of prematurity versus BW on these responses. Pigs delivered by caesarean section at preterm (103 d) or term (112 d) gestation were fed parenterally for 4 d. On day 4, all pigs were fasted for 4 h and were either fasted one additional hour or fed an elemental meal by oral gavage, yielding four treatment groups: preterm fasted, preterm fed, term fasted, and term fed. A flooding dose of L-[4-3H]Phe was injected into pigs 30 min after feeding (30 min before euthanasia). Preterm and term pigs were stratified according to birth weight such that preterm pigs with the highest birth weight were compared to term pigs with the lowest birth weight (n = 10–13 per group). Despite similar birth weight of pigs in these two subgroups, relative body weight gain of preterm pigs was 33% lower than term pigs (22.0 vs. 32.9 ± 1.6 g·kg-1·d-1, P < 0.001). Gastrocnemius protein synthesis increased after feeding in both preterm and term pigs, but the increase was 18% lower in preterm than in term pigs pigs (Table 1). Feeding-induced AKT phosphorylation and mTOR-dependent 4EBP1 and S6K1 phosphorylation mirrored the pattern in protein synthesis. These results suggest that prematurity (rather than low birth weight, which is frequently associated with preterm birth) perturbs mTOR activation and protein synthesis after feeding. However, it is unclear whether an inadequate response to feeding also underpins poor growth in intrauterine growth restricted piglets. Research was supported by NIH and USDA.
Critical Care Medicine, Dec 1, 2006
The FASEB Journal, Apr 1, 2015
Sepsis decreases protein synthesis (PS) in skeletal muscle and mitigates the anabolic response to... more Sepsis decreases protein synthesis (PS) in skeletal muscle and mitigates the anabolic response to Leucine (Leu) in mature animals. To determine if supplemental Leu can stimulate muscle PS in the ne...
The FASEB Journal, Apr 1, 2015
In neonatal animals, protein synthesis and degradation rates are high. Administration of the bran... more In neonatal animals, protein synthesis and degradation rates are high. Administration of the branched-chain amino acid, leucine (Leu), stimulates muscle protein synthesis in neonatal pigs but less ...
The FASEB Journal, Mar 1, 2006
Current Developments in Nutrition
Journal of Animal Science
Extrauterine growth restriction is a common complication of preterm birth and is associated with ... more Extrauterine growth restriction is a common complication of preterm birth and is associated with reduced lean growth and long-term morbidities. We previously showed that intermittent pulses of leucine during continuous orogastric feeding increases mTORC1 signaling to protein synthesis in skeletal muscle of neonatal pigs born at term. The objective of this study was to determine the extent to which leucine pulses during continuous feeding would promote lean growth by enhancing mTORC1 signaling in a preterm piglet model. Pigs delivered by cesarean section at 105 d gestation were continuously fed a protein and energy balanced milk-replacer diet [195 kcal ME and 13.5 g protein (kg body weight; BW)-1·d-1)]. Pigs (n=11-12) were randomly assigned to Leucine (LEU) or Alanine (ALA, isonitrogenous control) groups and treatments were administered as a pulse (1.6 mmol·kg BW-1·h-1) for 1 h every 4 h for 21 d. Body composition was determined by DXA and indices of amino acid signaling and mTORC1 a...
Current Developments in Nutrition
Objectives Previous work in our lab showed that continuous feeding blunts muscle protein synthesi... more Objectives Previous work in our lab showed that continuous feeding blunts muscle protein synthesis compared to intermittent bolus feeding in neonatal pigs born at term (a highly translatable model for the human neonate). However, continuous feeding is still indicated in some infants due to feeding intolerance. Our lab has demonstrated that leucine acts as a nutrient signal to stimulate protein synthesis and that intermittent parenteral leucine (Leu) pulses during continuous orogastric feeding increases skeletal muscle mTORC1 signaling and protein synthesis in neonatal pigs born at term. We hypothesized that leucine pulsing during continuous feeding enhances mTORC1 signaling to protein synthesis and lean growth in a preterm piglet model. Methods Pigs delivered by cesarean section at 105 d gestation were gradually transitioned over 7 d from parenteral to enteral feeding, via an orogastric tube, and continuously fed a protein and energy balanced milk-replacer diet (ME = 195 kcal/kg/d; ...
The FASEB Journal, Apr 1, 2013
Orogastric tube feeding is recommended in neonates unable to ingest food normally, and can be adm... more Orogastric tube feeding is recommended in neonates unable to ingest food normally, and can be administered by intermittent bolus (INT) or continuous (CON) infusion. Recently, we showed that INT compared to CON feeding enhances lean tissue accretion by increasing muscle protein synthesis in neonates. To determine the mechanism for this response, neonatal pigs (n=6, 6‐d‐old) were fed the same diet in equivalent amounts continuously or intermittently (meal every 4h) for 21d. Insulin receptor and insulin receptor substrate 1 expression and protein kinase B phosphorylation in skeletal muscle were unaffected by feeding modality. Formation of the active eukaryotic initiation factor (eIF) 4E‐eIF4G complex and phosphorylation of ribosomal protein S6 kinase were higher and phosphorylation of eIF2α was lower in INT compared to CON fed pigs indicating increased translation initiation (P<0.05). Sodium‐coupled neutral amino acid transporter 2, but not L‐type amino acid transporter 1, expression was higher in INT compared to CON pigs suggesting enhanced glutamine transport (P<0.05). Abundance of the ubiquitin ligases, muscle RING finger‐1 and F‐box protein atrogin‐1/MAFbx, was higher for INT compared to CON pigs (P<0.05). These results suggest that intermittent feeding enhances lean tissue accretion by increasing amino acid transport and protein turnover. (Supported by NIH AR444474 and USDA/ARS 6250–51000‐055)
Energy and protein metabolism and nutrition. 3rd EAAP International Symposium on Energy and Protein Metabolism and Nutrition, Parma, Italy, 6-10 September, 2010, 2010
Energy and protein metabolism and nutrition. 3rd EAAP International Symposium on Energy and Protein Metabolism and Nutrition, Parma, Italy, 6-10 September, 2010., 2010
The FASEB Journal, Apr 1, 2012
The FASEB Journal, Apr 1, 2011
Advances in Nutrition, 2016
Additional resources on what your abstract will be scored on and how to present can be found on t... more Additional resources on what your abstract will be scored on and how to present can be found on this page as well as on the ASN website. Make sure to choose an abstract category from the drop down list, pictured to the left.
Wageningen Academic Publishers eBooks, 2013
Orogastric tube feeding is indicated in neonates with impaired ability to ingest food normally an... more Orogastric tube feeding is indicated in neonates with impaired ability to ingest food normally and can be administered by intermittent bolus (INT) or continuous (CON) infusion. Insulin and amino acids play important roles in the regulation of protein synthesis in the neonate. While the sensitivity to insulin is developmentally regulated (Davis et al., 1998) and greatly diminishes with age (Wray-Cahen et al., 1997), amino acids exert a positive effect on muscle protein synthesis throughout life (Denne et al., 1991; Davis et al., 1998; Volpi et al., 1998). In addition to providing amino acids to other organs when dietary supplies are insufficient, high rates of proteolysis are necessary to provide amino acids for ongoing tissue modeling and rapid growth. The two most important proteolytic pathways in skeletal muscle are thought to be the ubiquitin-proteasome and autophagy-lysosome systems (Ventadour and Attaix, 2006). The aim of this study was to determine if these feeding modalities affect growth and lean tissue accretion, and the mechanisms for this response.
The FASEB Journal, Apr 1, 2007
Journal of Parenteral and Enteral Nutrition, Oct 10, 2022
Current developments in nutrition, Jun 1, 2022
Journal of Animal Science, Oct 8, 2021
Continuous feeding does not elicit an optimal anabolic response but is required for some prematur... more Continuous feeding does not elicit an optimal anabolic response but is required for some premature infants. We reported previously that intermittent intravenous pulses of Leu (800 μmol Leu·kg-1·h-1 every 4 h) to continuously fed pigs born at term enhanced skeletal muscle mTOR signaling and protein synthesis (PS). The objective of this study was to determine if the anabolic response of skeletal muscle to intermittent Leu pulses is altered following premature birth. Pigs delivered 10 d preterm by cesarean section were advanced to full oral feeding over four days (195 kcal·kg-1·d-1; 13.5 g protein·kg-1·d-1). Pigs were assigned to 1 of 4 treatments: 1) ALA (continuous feeding; 800 μmol Ala·kg-1·h-1 every 4 h; n = 7); 2) L1× (continuous feeding; 800 μmol Leu·kg-1·h-1 every 4 h; n = 6); 3) L2× (continuous feeding; 1600 μmol Leu·kg-1·h-1 every 4 h; n = 6); and 4) INT (intermittent feeding every 4 h; n = 5). Pigs received a Phe tracer 30 min following the amino acid pulse or intermittent feeding to measure PS in longissimus dorsi muscle. Anabolic signaling downstream of mTOR was determined by immunoblot.ResultsPS was higher in L2× and INT compared to ALA (P < 0.05) but was not different between L2× and INT; PS in L1× was intermediate and not different from other groups. Phosphorylation of 4EBP1 and S6K1 was higher in INT compared to L1× and ALA groups (P < 0.05) but was not different compared to L2×. Phosphorylation of 4EBP1, but not S6K1, was higher in L2× compared to ALA (P < 0.05); phosphorylation of 4EBP1 and S6K1 was not different between L1× and L2×.ConclusionsThese results demonstrate that intravenous Leu enhances mTOR activation and PS in LD muscle of continuously fed preterm pigs. However, the amount required may be higher than in pigs born at term.Source of Research SupportNIH and USDA.
The FASEB Journal, Apr 1, 2016
When neonatal pigs continuously fed formula are supplemented with leucine pulses, muscle protein ... more When neonatal pigs continuously fed formula are supplemented with leucine pulses, muscle protein synthesis and body weight gain are enhanced. To identify the responsible mechanisms, we combined plasma metabolomic analysis with transcriptome expression of the transcriptome and protein catabolic pathways in skeletal muscle. Piglets (n = 23, 7-day-old) were fed continuously a milk replacement formula via orogastric tube for 21 days with an additional parenteral infusion (800 μmol kg −1 h −1) of either leucine (LEU) or alanine (CON) for 1 h every 4 h. Plasma metabolites were measured by liquid chromatography-mass spectrometry. Gene and protein expression analyses of longissimus dorsi muscle were performed by RNA-seq and Western blot, ✉
Journal of Animal Science, Nov 3, 2020
Postnatal growth failure reduces lean mass accretion and increases adiposity. Previously we showe... more Postnatal growth failure reduces lean mass accretion and increases adiposity. Previously we showed that preterm birth impairs the feeding-induced stimulation of mechanistic target of rapamycin (mTOR), translation initiation, and protein synthesis in skeletal muscle of neonatal pigs. Considering that pig body weight can vary widely at birth, we wished to differentiate the effect of prematurity versus BW on these responses. Pigs delivered by caesarean section at preterm (103 d) or term (112 d) gestation were fed parenterally for 4 d. On day 4, all pigs were fasted for 4 h and were either fasted one additional hour or fed an elemental meal by oral gavage, yielding four treatment groups: preterm fasted, preterm fed, term fasted, and term fed. A flooding dose of L-[4-3H]Phe was injected into pigs 30 min after feeding (30 min before euthanasia). Preterm and term pigs were stratified according to birth weight such that preterm pigs with the highest birth weight were compared to term pigs with the lowest birth weight (n = 10–13 per group). Despite similar birth weight of pigs in these two subgroups, relative body weight gain of preterm pigs was 33% lower than term pigs (22.0 vs. 32.9 ± 1.6 g·kg-1·d-1, P < 0.001). Gastrocnemius protein synthesis increased after feeding in both preterm and term pigs, but the increase was 18% lower in preterm than in term pigs pigs (Table 1). Feeding-induced AKT phosphorylation and mTOR-dependent 4EBP1 and S6K1 phosphorylation mirrored the pattern in protein synthesis. These results suggest that prematurity (rather than low birth weight, which is frequently associated with preterm birth) perturbs mTOR activation and protein synthesis after feeding. However, it is unclear whether an inadequate response to feeding also underpins poor growth in intrauterine growth restricted piglets. Research was supported by NIH and USDA.
Critical Care Medicine, Dec 1, 2006
The FASEB Journal, Apr 1, 2015
Sepsis decreases protein synthesis (PS) in skeletal muscle and mitigates the anabolic response to... more Sepsis decreases protein synthesis (PS) in skeletal muscle and mitigates the anabolic response to Leucine (Leu) in mature animals. To determine if supplemental Leu can stimulate muscle PS in the ne...
The FASEB Journal, Apr 1, 2015
In neonatal animals, protein synthesis and degradation rates are high. Administration of the bran... more In neonatal animals, protein synthesis and degradation rates are high. Administration of the branched-chain amino acid, leucine (Leu), stimulates muscle protein synthesis in neonatal pigs but less ...
The FASEB Journal, Mar 1, 2006
Current Developments in Nutrition
Journal of Animal Science
Extrauterine growth restriction is a common complication of preterm birth and is associated with ... more Extrauterine growth restriction is a common complication of preterm birth and is associated with reduced lean growth and long-term morbidities. We previously showed that intermittent pulses of leucine during continuous orogastric feeding increases mTORC1 signaling to protein synthesis in skeletal muscle of neonatal pigs born at term. The objective of this study was to determine the extent to which leucine pulses during continuous feeding would promote lean growth by enhancing mTORC1 signaling in a preterm piglet model. Pigs delivered by cesarean section at 105 d gestation were continuously fed a protein and energy balanced milk-replacer diet [195 kcal ME and 13.5 g protein (kg body weight; BW)-1·d-1)]. Pigs (n=11-12) were randomly assigned to Leucine (LEU) or Alanine (ALA, isonitrogenous control) groups and treatments were administered as a pulse (1.6 mmol·kg BW-1·h-1) for 1 h every 4 h for 21 d. Body composition was determined by DXA and indices of amino acid signaling and mTORC1 a...
Current Developments in Nutrition
Objectives Previous work in our lab showed that continuous feeding blunts muscle protein synthesi... more Objectives Previous work in our lab showed that continuous feeding blunts muscle protein synthesis compared to intermittent bolus feeding in neonatal pigs born at term (a highly translatable model for the human neonate). However, continuous feeding is still indicated in some infants due to feeding intolerance. Our lab has demonstrated that leucine acts as a nutrient signal to stimulate protein synthesis and that intermittent parenteral leucine (Leu) pulses during continuous orogastric feeding increases skeletal muscle mTORC1 signaling and protein synthesis in neonatal pigs born at term. We hypothesized that leucine pulsing during continuous feeding enhances mTORC1 signaling to protein synthesis and lean growth in a preterm piglet model. Methods Pigs delivered by cesarean section at 105 d gestation were gradually transitioned over 7 d from parenteral to enteral feeding, via an orogastric tube, and continuously fed a protein and energy balanced milk-replacer diet (ME = 195 kcal/kg/d; ...