J López-Hellin

University Hospital Vall d'Hebron, Barcino, Catalonia, Spain

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Publications (11)26.76 Total impact

  • e-SPEN the European e-Journal of Clinical Nutrition and Metabolism 01/2010; 5(5).
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    ABSTRACT: The metabolic response to injury includes major alterations in protein metabolism; however, little is known about alterations in the synthesis of individual proteins and their role in the stress response. Our aim was to study how individual proteins in liver and muscle are altered by abdominal surgery. Changes produced in mRNA and proteins by abdominal surgery were studied in rats using RAP (random arbitrary priming)-PCR, to investigate mRNA alterations, and standard or isotopic (with in vivo radioactive labelling of proteins) two-dimensional electrophoresis/MS proteomic analyses, to study differential expression of proteins. Many of the differentially expressed proteins identified in blood were specifically synthesized by the liver to participate in the stress response. The hepatic proteins (antioxidant proteins, serine protease inhibitors, acute-phase proteins and transport proteins) were secreted into the bloodstream to produce a systemic action, indicating the central role of the liver in the stress response. Overexpressed proteins identified in liver were associated with the glycolytic processes and the folding of nascent proteins, confirming the high metabolic activity of the liver after surgery. The role of skeletal muscle protein as an amino acid donor to fuel the processes involved in the stress response was shown by the decrease in high-molecular-mass myofibrillar proteins. Combined use of the three techniques studied, differential RAP-PCR and standard and isotopic proteome analysis, provided complementary information on the differentially expressed proteins in a rat model of surgical stress.
    Clinical Science 03/2005; 108(2):167-78. · 4.86 Impact Factor
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    ABSTRACT: The metabolic response to surgery includes a net loss of proteins that influences negatively the clinical evolution of the patients. We investigated the effect of perioperative nutrition on protein metabolism alterations immediately after surgery. A control group of 21 surgery patients were submitted to conventional perioperative nutritional protocol (18 h of fasting plus low-dose glucose after surgery). An experimental group of eight similar patients was given complete parenteral nutrition during 24 h before and 24 h after surgery. Nitrogen balance, whole body protein synthesis, breakdown, and 3-methylhistidine were determined before surgery and 24 h after surgery. The immediate response to surgery with conventional nutritional management was a net protein loss (-1.023 g prot. kg(-1) day(-1)), caused by an increase in the protein breakdown (137.9% of preoperative values), while the protein synthesis remained unchanged (98.4%). The 3-methylhistidine excretion was not increased in respect to perioperative values, suggesting that the degraded protein was not from muscular origin. The experimental group with perioperative nutrition showed neither protein loss (+0.075 g prot. kg(-1) day(-1)) nor changes in protein synthesis or breakdown vs. preoperative values (96.3% and 88.0%, respectively). Perioperative nutrition prevents the early protein losses after gastrointestinal surgery.
    Clinical Nutrition 11/2004; 23(5):1001-8. · 3.30 Impact Factor
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    ABSTRACT: Biochemical indicators are used to assess the adequacy of nutritional support given to postoperative patients. However, the metabolic alterations present in these patients diminish the efficiency of these indicators. The objective of this work is to determine the usefulness of short-lived proteins as indicators to assess the nutritional support administered to patients during the metabolic stress phase produced by surgery. The nitrogen balance and plasma concentrations of transthyretin, retinol binding protein, and insulin-like growth factor-1 were determined in 24 patients who received 4 different nutritional regimens during 7 days after surgery. Transthyretin and retinol binding protein, although sensitive to nutritional intake (P<0.0005 and P<0.04 respectively), were strongly affected by the stress response (P<0.008 and P<0.0003 respectively), thus limiting their usefulness for nutrition assessment. Insulin-like growth factor-1 was not influenced by the stress response and was sensitive to the nutritional supply (P<0.0001). Insulin-like growth factor-1 was the only component that showed similar efficiency than nitrogen balance as nutritional indicator. Transthyretin and retinol binding protein are not adequate to assess the nutritional supply during the stress phase after surgery, while insulin-like growth factor-1 is a suitable indicator of the adequacy of recent intake in this situation, similar in performance to nitrogen balance.
    Clinical Nutrition 05/2002; 21(2):119-25. · 3.30 Impact Factor
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    ABSTRACT: To investigate the amino acid requirements of the senescent rat, as part of a study directed toward nutritional support in the aged, it was necessary to determine amino acid levels in plasma and tissue, but also regional blood flow of the animals subjected to fast. Only this latter allows the determination of the amounts of each amino acid present in the tissue before starvation by extrapolation of values measured during starvation. As plasma and tissue amino acid had been previously determined, the aim of this study had been to measure regional blood flow in the liver, kidney, testis, spleen, stomach, small intestine and large intestine in senescent rats submitted to 1, 5, 9 and 15 days of starvation. Twenty-four-month-old male Wistar rats (n = 16) were divided into four groups (n = 4), and submitted to starvation for 1, 5, 9 and 15 days. Blood flow in the liver, kidney, testis, spleen, stomach, and small and large intestine was measured by injecting 0.5 ml of a microsphere solution (15 microns diameter) labelled with 57Co, 0.25 microCi/ml. Over the 15-day period studied, the response to starvation showed two distinct phases: an early effect (from day 1 to day 9) in which there were decreases in the weight of the organs and in organ blood flow, and a second phase (from day 9 to day 15) in which blood flow and organ weight were maintained. However, organ blood flow related to mass was not substantially affected by starvation. This implies that measurement of substrate plasma concentration alone can reliably reflect organ substrate flow.
    Archives of Physiology and Biochemistry 09/1998; 105(4):337-41.
  • E García-Arumí, A L Andreu, J López-Hellín, S Schwartz
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    ABSTRACT: 1. Oxidative damage has been associated with ageing, but there is no agreement as to whether or not it is produced by a decrease in antioxidant defences with the ageing process. In purified lymphocytes from 47 healthy elderly (75.27 +/- 0.91 years) and 47 healthy young (29.87 +/- 0.53 years) volunteers, we studied the levels of antioxidant enzyme activity (superoxide dismutase, catalase and glutathione peroxidase), protein oxidative damage (as protein carbonyl content) and lysosomal proteolytic activity (cathepsins B, H and L), with and without exposure to oxidative stress produced by 25 mumol/l H2O2. 2. There were no differences in antioxidant enzyme activities in the stressed and non-stressed samples between the young and elderly subjects, indicating that there was no relationship between age and antioxidant enzyme activity even in oxidative stress. However, a dissimilar response to oxidative stress was observed in protein oxidative damage and cathepsin B and L activities, depending on the age of the donor. 3. With these results we conclude that oxidative stress produces greater protein oxidative damage and increased protein degradation in elderly subjects than in young ones; this effect cannot be attributed to dissimilar antioxidant enzyme responses to oxidative stress, since these did not differ between the two age groups.
    Clinical Science 05/1998; 94(4):447-52. · 4.86 Impact Factor
  • J Lopez-Hellin, E Garcia-Arumi, S Schwartz
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    ABSTRACT: Cumulative damage in cells from aged people could lead to a greater fragility against acute oxidative stress. The effects of acute oxidative stress on cell viability, cAMP and cGMP concentrations, and protein synthesis rates were studied in lymphocytes from 25 young and 26 elderly subjects. Lymphocytes were exposed to stress by hydrogen peroxide 25 micromol/l and incubated for 18 hours. Cell viability after stress was lower (p<0.0001, Student's t test) in cells from the elderly (63.4%) than in cells from the young donors (73.2%). The protein synthesis rate was also lower after stress (p<0.04, Mann-Whitney U test) in cells from the elderly (47.3% vs. non-stressed cells), than in cells from the young (82.19% vs. non-stressed cells). After oxidative stress, cAMP and cGMP concentrations showed no significant changes in cells from young subjects; there were, however, significant decreases in these cyclic nucleotides in cells from the elderly (p<0.008 for both nucleotides, paired Student's t test). There were no differences in basal cAMP or cGMP levels between the two groups. These results show that mortality and metabolic changes due to oxidative stress are greater in lymphocytes proceeding from elderly subjects than in those from young subjects.
    Life Sciences 02/1998; 63(1):13-21. · 2.56 Impact Factor
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    ABSTRACT: This work attempts to determine if there are differences in protein metabolism in post-surgical patients who receive parenteral nutrition with amino acids plus glucose (G+AA) or conventional gluco-salinal solution (GS). Eighteen patients submitted to gastrointestinal surgery were randomized and double-blindly administered either G+AA (1 g AA/kg x d and 28 kJ/kg x d), or GS (28 kJ/kg x d). Protein metabolism was determined 12 h after surgery (day 0) and after 5 days of nutritional support. On day 0, protein breakdown was similarly elevated, with respect to reference values, in both groups (GS: 4.62 +/- 0.25; G+AA: 5.25 +/- 0.50 g prot/kg x d) as a result of surgical stress. These values increased significantly at day 5 (P < 0.03) with the administration of GS to 6.93 +/- 1.00 g prot/kg x d, while they decreased (P < 0.002, 3.30 +/- 0.42 g prot/kg x d) with G+AA. Protein synthesis was increased (5.69 +/- 0.86 g prot/kg x d) with GS (P < 0.02), and was decreased (2.79 +/- 0.44 g prot/kg x d) with G+AA (P < 0.0002). Both synthesis and breakdown were inside normal reference values after 5 days for group G+AA. In both groups, nitrogen balance did not change significantly at day 5 compared to day 0. G+AA is effective in curbing the hypermetabolism produced by postoperative stress, achieving normal protein metabolism in 5 days, while GS increases the protein breakdown and synthesis. Nitrogen balance does not detect these modifications of the protein metabolism. Undernutrition on prognosis is not yet fully recognized.
    Clinical Nutrition 04/1997; 16(2):67-73. · 3.30 Impact Factor
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    ABSTRACT: We have studied the effects of hypocaloric diets with different supplements on liver and jejunal mucosa protein synthesis. The supplements assayed were medium chain triglycerides (diet MCT, with 50% carbohydrates: 25% long chain triglycerides (LCT): 25% medium chain triglycerides (MCT), standard amino acids), branched-chain amino acids (diet BCA, identical to control diet L50, with 15.3% of nitrogen replaced by branched-chain amino acids) and glutamine (diet GLN, identical to diet L50, with 15.3% of nitrogen replaced by glutamine). The control diet (L50) had 50% carbohydrates: 50% LCT and standard amino acids. The diets were assayed on 86 rats with femoral fracture immobilized by Kirschner pin insertion. Nutrition was administered for 4 days. On the fifth day, liver and jejunal mucosa protein synthesis was determined. A branched-chain amino acid supply in a proportion higher than 21.2% of amino acid nitrogen significantly decreased liver and jejunal mucosa protein synthesis, while the same amount of glutamine did not modify it. MCT had no effect on jejunal mucosa protein synthesis, while it was decreased significantly in the liver.
    Physiological research / Academia Scientiarum Bohemoslovaca 02/1997; 46(3):181-6. · 1.53 Impact Factor
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    ABSTRACT: The aim of this work was to study the effects of low energy parenteral diets with different lipid/glucose ratios on rat liver and jejunal mucosa protein synthesis. The studied diets were: L0 (100% glucose, control diet), L25 (25% lipids: 75% glucose), L50 (50% lipids: 50% glucose) and L75 (75% lipids: 25 % glucose). All diets were isoenergetic and isonitrogenated, with a standard amino acid content. The diets were assayed in 93 rats with open femoral fracture immobilized by Kirschner pin insertion. The diets were administered for 4 days. On the fifth day, liver and jejunal mucosa protein synthesis were determined. Highest liver protein synthesis rates were obtained with the diet compositions: lipid/carbohydrate ratio: 25% lipids and 75% carbohydrates (expressed as energy ratio). A higher proportion of lipids significantly decreases liver protein synthesis (p <0.05). Jejunal mucosa protein synthesis followed the same pattern, with the same statistical differences.
    Physiological research / Academia Scientiarum Bohemoslovaca 01/1997; 46(3):187-91. · 1.53 Impact Factor
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    ABSTRACT: To investigate the effect of glutamine-enriched total parenteral nutrition (TPN) on the protein synthesis and morphology of jejunal mucosa in non-hypercatabolic stress, sixty-two male Sprague-Dawley rats were subjected to surgical stress by femoral fracture. The rats were divided into 3 groups and received TPN for 8 days. One group received a standard amino acid solution without glutamine, the second group a standard solution enriched with glycine and glutamic acid, and the third group a standard solution enriched with glycyl-glutamine. All regimens were isocaloric and isonitrogenous-nitrogen (2.2 g/kg.day), glucose (150 Kcal/kg.day), and lipids (150 Kcal/kg.day). There were no statistically significant differences in jejunal mucosal thickness, DNA content, protein content, fractional synthesis rate or absolute protein synthesis among the groups after eight days of parenteral nutrition. In conclusion, the addition of glutamine to TPN did not influence either protein metabolism or morphology of the jejunal mucosa in non-hypercatabolic surgical stress.
    Physiological research / Academia Scientiarum Bohemoslovaca 02/1995; 44(4):233-9. · 1.53 Impact Factor