Papers by Jorge Maldonado
Experimental and clinical cardiology
Background: Exacerbated post-surgery inflammation likely leads to adverse clinical outcomes (ACO)... more Background: Exacerbated post-surgery inflammation likely leads to adverse clinical outcomes (ACO). Given the antiinflammatory properties of n-3LC-PUFA potential beneficial effects are expected in patients with myocardial revascularization.
![Research paper thumbnail of [Homocysteine after a methionine load in healthy subjects with adequate B-vitamin status]](https://attachments.academia-assets.com/44986643/thumbnails/1.jpg)
Cirugía y cirujanos
Plasma homocysteine (Hcy) determination at 6-8 h after an oral methionine load (OML) allows for i... more Plasma homocysteine (Hcy) determination at 6-8 h after an oral methionine load (OML) allows for identification of some, but not all, individuals at risk to develop cardiovascular disease. It is probable that in some cases the Hcy increases occur later, or it elevates between normal ranges but in a sustained manner. However, the entire Hcy response curve has not been described. We undertook this study to determine Hcy concentrations from baseline to 24- and 48-h after an OML in non-B-vitamin deficient adult subjects with other risk factors for high levels of Hcy such as smoking and overweight. In a cross-over, clinical design, Hcy concentrations were determined at 2-h intervals throughout 12 h and at 24 h and 48 h after an OML (0.1 g/kg). Hcy and vitamin B6 (VB6) concentrations were measured by high-performance liquid chromatography (HPLC). Folic acid (FA) and vitamin B12 (VB12) were measured by radioimmunoassay (RIA). Statistical analysis included delta values and areas under the cu...
![Research paper thumbnail of The [ 13 C]Glucose Breath Test Is a Reliable Method to Identify Insulin Resistance in Mexican Adults Without Diabetes: Comparison with Other Insulin Resistance Surrogates](https://attachments.academia-assets.com/44986679/thumbnails/1.jpg)
Diabetes Technology & Therapeutics, 2014
Background: Insulin resistance (IR) precedes type 2 diabetes, but tests used to detect it in clin... more Background: Insulin resistance (IR) precedes type 2 diabetes, but tests used to detect it in clinical settings reported poor reproducibility. We assessed the reliability of the [ 13 C]glucose breath test ( 13 C-GBT) in a sample of subjects without diabetes. Repeatability of the test was compared with that of other IR surrogates derived from the fasting or oral glucose tolerance test (OGTT). Subjects and Methods: Eighty-six healthy volunteers received an oral load of 75 g of glucose in 150 mL of water followed by 1.5 mg/kg of [U-13 C]glucose in 50 mL of water. Breath and blood samples were collected at baseline and at 10, 20, 30, 60, 90, 120, 150, and 180 min following the glucose load; the same procedure was repeated within 1 week. The enrichment of breath 13 CO 2 was measured by ratio mass spectrometry and expressed as percentage oxidized dose at a given time period. Intrasubject variability was assessed with Bland-Altman plots and coefficients of variation (CVs). Results: The overall CV of the 13 C-GBT was 12.99 -11.61%, compared with 18.42% of fasting insulin, 19.44% for homeostasis model assessment, 17.06% of the composite insulin sensitivity index, and 29.99% for insulin in the 2-h oral glucose tolerance test. The variability of the 13 C-GBT tended to be higher in lean (17.40%) than in overweight (10.17%) and obese (12.61%) individuals. Conclusions: The variability of the 13 C-GBT is lower than that of other IR surrogates, making it a reproducible method to estimate insulin sensitivity in overweight and obese adults without diabetes. Because the individuals did not have diabetes but were within a high range of insulin sensitivity, the test should have application in clinical and population-based studies, given the evidence for the utility and limitations of this surrogate.
Clinical Chemistry and Laboratory Medicine (CCLM), 2015
Metabolic syndrome (MS) is an important risk factor in pediatric population for the early onset o... more Metabolic syndrome (MS) is an important risk factor in pediatric population for the early onset of type 2 diabetes mellitus and cardiovascular disease. New non-invasive tools are required to identify MS in at risk populations; the aim of this study was to determine an optimal cut-off point for the 13C-glucose breath test (13C-GBT) for the diagnosis of MS in adolescents. A total of 136 adolescents between 10 and 16 years old were recruited. MS was defined as: waist circumference >90th percentile and at least two of the following; high density lipoprotein-cholesterol (HDL-C) <50 mg/dL, triglycerides >110 mg/dL, diastolic and/or systolic blood pressure >90th percentile adjusted by age, gender and height, and/or fasting glucose >100 mg/dL. After the ingestion of a glucose load of 1.75 g/kg of body weight (up to 75 g) and an oral dose of 1.5 mg of universally labeled 13C-glucose/kg dissolved in water, breath samples were taken at baseline, 30, 60, 90, 120, 150 and 180 min. Exhaled 13CO2 in breath samples was measured by isotope ratio mass spectrometry. 13C-GBT data, expressed as adjusted cumulative percentage of oxidized dose (A% OD) at 180 min, was significantly higher in the healthy subjects group (17.72%±4.9%) in comparison with subjects with ≥3, 2 or 1 components of the MS (9.95%±4.73%, 14.3%±4.47% and 14.62%±4.62%, respectively). The optimal cut-off point for the A% OD was 16.09, with a sensitivity of 81.5% and a specificity of 66.7%. Our results demonstrate that the 13C-glucose breath test could be a valid screening method to identify MS in adolescents.
Gene, 2014
During pregnancy and lactation, metabolic adaptations involve changes in expression of desaturase... more During pregnancy and lactation, metabolic adaptations involve changes in expression of desaturases and elongases (Elovl2 and Elovl5) in the mammary gland and liver for the synthesis of long-chain polyunsaturated fatty acids (LC-PUFAs) such as arachidonic acid (AA) required for fetal and postnatal growth. Adipose tissue is a pool of LC-PUFAs. The response of adipose tissue for the synthesis of these fatty acids in a lipid-deficient diet of dams is unknown. The aim of this study was to explore the role of maternal tissue in the synthesis of LC-PUFAs in rats fed a low-lipid diet during pregnancy and lactation. Fatty acid composition (indicative of enzymatic activity) and gene expression of encoding enzymes for fatty acid synthesis were measured in liver, mammary gland and adipose tissue in rats fed a low-lipid diet. Gene expression of desaturases, elongases, fatty acid synthase (Fasn) and their regulator Srebf-1c was increased in the mammary gland, liver and adipose tissue of rats fed a low-lipid diet compared with rats from the adequate-lipid diet group throughout pregnancy and lactation. Genes with the highest (P<0.05) expression in the mammary gland, liver and adipose tissue were Elovl5 (1333%), Fads2 (490%) and Fasn (6608%), respectively, in a low-lipid diet than in adequate-lipid diet. The percentage of AA in the mammary gland was similar between the low-lipid diet and adequate-lipid diet groups during the second stage of pregnancy and during lactation. The percentage of monounsaturated and saturated fatty acids was significantly (P<0.05) increased throughout pregnancy and lactation in all tissues in rats fed a low-lipid diet than in rats fed an adequate-lipid diet. Results suggest that maternal metabolic adaptations used to compensate for lipid-deficient diet during pregnancy and lactation include increased expression of genes involved in LC-PUFAs synthesis in a stage- and tissue-specific manner and elevated lipogenic activity (saturated and monounsaturated fatty acid synthesis) of maternal tissues including adipose tissue.
Food and Nutrition Sciences, 2013
The type of fat consumed in the Mexican diet could predispose to the development of Metabolic Syn... more The type of fat consumed in the Mexican diet could predispose to the development of Metabolic Syndrome (MS) which has been associated with an increased risk to develop cardiovascular disease and type 2 diabetes mellitus. Our study included adolescents between 12 and 16 years of age, divided in two groups: Control Group (n = 31) and MS Group (n = 44). Waist circumference, blood pressure, fasting glucose, triglycerides, and HDL-cholesterol were determined. Erythrocytes' fatty acids methyl esthers were quantified using gas chromatography with ionized flame detector. We identified 16 fatty acids (FA) with chain lengths from C12 to C24, with emphasis in four trans FA (TFA) isomers: vaccenic (C18:1n7t), elaidic (C18:1n9t), linoelaidic (C18:2n6t), and conjugated linoelaidic acids (C18:2n7t). MS Group had a less proportion of: myristic (C14), palmitoleic (C16:1), C18:1n7t, and linoleic acids (C18:2); and a higher one of C18:1n9t, C18:2n7t, and nervonic acids (C24:1) when compared to the control group. C24:1 and C18:1n9t had a significant positive association with MS (OR = 14.17 and OR = 12.94, respectively); whereas C14 (OR = 0.14), C18:1n7t (OR = 0.14), and C18:2 (OR = 0.22) appear to have a protective effect against the disease. The proportion of specific FAs in erythrocytes' membranes differs between adolescents with MS and healthy controls; these FA not only showed a strong association with MS, but also correlated with most of its individual components. Interestingly, TFA displayed an antagonic behavior; while C18:1n9t had a strong association with MS, apparently C18:1n7t confers a protective effect; these results suggest that analyzing each TFA separately will constitute a more accurate approach to determine the role of TFAs in the pathogenesis of MS or other related metabolic disorders.
Nutrition, 2009
Objective: We examined the effect of different amounts of dietary corn oil rich in linoleic acid ... more Objective: We examined the effect of different amounts of dietary corn oil rich in linoleic acid (LA) on the endogenous synthesis of arachidonic acid (AA), uptake of its precursor LA, and fatty acid composition of tissues involved in the supply of long-chain polyunsaturated fatty acids for milk synthesis. Methods: Female Sprague Dawley rats received one of the following diets during pregnancy and lactation: a low-lipid diet (LLD; 2%), an adequate-lipid diet (ALD; 5%), or a high-lipid diet (HLD; 10%). Lipids were provided by corn oil. On day 12 of lactation we measured the endogenous synthesis of AA and quantified the conversion of 13 C-LA to 13 C-AA and the metabolic fate of 13 C-LA from all dietary groups.
Nutrition, 2006
Objective: We tested the hypothesis of whether a pharmacologic, orogastric dose of docosahexaenoi... more Objective: We tested the hypothesis of whether a pharmacologic, orogastric dose of docosahexaenoic acid (DHA) administered during the acute phase of sepsis protects the nutritional status of neonates. Methods: A randomized, placebo-controlled trial was conducted. Neonates who developed sepsis after a surgical procedure were randomly assigned to receive daily 100 mg of DHA or 100 mg of olive oil as placebo for 14 d. At selection, illness severity was evaluated and a blood sample was obtained to measure erythrocyte fatty acid composition. Energy intake and type of feeding were recorded daily. Body composition was also determined at selection and after 14 d of follow-up with the deuterium dilution technique. Body composition differences between d 14 and baseline were calculated and compared between groups. Confounders were analyzed in a multiple regression model. Results: In all, 16 DHA and 11 placebo cases were followed up. Both groups showed an increase in length and head circumference, but length gain tended to be greater in neonates with DHA (P ϭ 0.07). The DHA group presented increases in body mass (50 g, P ϭ 0.03) and fat mass (70 g, P ϭ 0.03), whereas infants in the placebo group did not show an increase in any body composition components. Gain in fat mass was positively related with the DHA of erythrocytes and whether or not infants received DHA. Conclusions: Orogastric DHA administered in the acute phase of infection likely protects the nutritional status of neonates with sepsis.
The Lancet, 2004
Obstacles to health information for all. By - Zoilo Cuellar-Montoya, Jorge E Maldonado, Alvaro Mo... more Obstacles to health information for all. By - Zoilo Cuellar-Montoya, Jorge E Maldonado, Alvaro Moncayo.
Clinical Chemistry and Laboratory Medicine, 2000
Hyperhomocysteinemia (Hhcy) is considered an independent risk factor for vascular diseases and, m... more Hyperhomocysteinemia (Hhcy) is considered an independent risk factor for vascular diseases and, more recently, for dementia. The methionine loading test (MLT) is useful for diagnosing additional subjects with moderate Hhcy. However, it is a complex and time-consuming procedure. A noninvasive test for the diagnosis of moderate Hhcy is desirable. The study protocol consisted of three consecutive visits. During the first visit, we performed an MLT to characterize the Hhcy status of 75 healthy adult subjects. For the breath test protocol, we selected a subsample and assigned to the control group 17 subjects with fasting and post-loading homocysteine (Hcy) ≤12 and <42.3 μmol/L, respectively, and to the Hhcy group 16 subjects with fasting Hcy ≤12 and >42.3 μmol/L after loading. Selected subjects were requested to have a second visit to perform a breath test within 1-4 weeks following the MLT test and received an oral dose of 2.5 mg/kg of 1-13C-methionine dissolved in water. Breath samples were collected at basal, 20, 40, 60, 80, 100 and 120 min (test 1). The same procedure was repeated within 1 week (test 2). MLT was useful for diagnosing almost twice the number of individuals with Hhcy (24%) in comparison with the fasting determination alone (13.3%). The 13C-methionine breath test reported a sensitivity of 81.3% and a specificity of 64.7% against the MLT. The coefficient of variation between breath test 1 and breath test 2 was 9.0±5.4%. The 13C-methionine breath test is a valid and reliable method for identifying subjects with moderate Hhcy.
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids, 2011
Fatty acid desaturase 1 Fatty acid desaturase 2 Elongase 5 Sterol-regulatory element binding fact... more Fatty acid desaturase 1 Fatty acid desaturase 2 Elongase 5 Sterol-regulatory element binding factor Pregnancy Lactation Metabolic adaptations are triggered in the maternal organism to synthesize milk with an adequate concentration of long-chain polyunsaturated fatty acids (LC-PUFAs) required to the newborn. They may be a high uptake of dietary linoleic acid and its conversion to LC-PUFAs by desaturases of fatty acids (FADS) 1 and 2 in the mammary gland (MG). It is unknown if they also occur from onset of pregnancy. The aim of this study was to explore the participation of the MG as a mechanism involved in LC-PUFAs synthesis to support their demand during pregnancy and lactation in rats. The expression of desaturases in MG was significantly (P b 0.05) higher (12.3-fold for FADS1 and 41.2-fold for FADS2) during the late pregnancy and throughout lactation (31.7-fold for FADS1 and 67.1-fold higher for FADS2) than in nonpregnant rats. SREBF-1c showed a similar pattern of increase during pregnancy but remained higher only during the early lactation (11.7-fold, P b 0.005). Transcript of ELOVL6 and FASN increased throughout pregnancy and lactation, respectively. ELOVL5 mRNA increased in MG only during lactation (2.8 to 5.3-fold, P b 0.005). Accordingly, a higher content of LC-PUFAs was found in lactating MG than in nonpregnant rats. Results suggest that MG participates from late pregnancy and throughout lactation by expressing desaturases and elongases as a mechanism involved in LC-PUFAs synthesis, probably by SREBF-1c. Because desaturases and ELOVL5 were expressed in cultured lactocytes and such expression was downregulated by linoleic and arachidonic acid, these cells may be a useful model for understanding the regulatory mechanisms for LC-PUFAs synthesis in MG.
Water, Air, and Soil Pollution, 2008
Oikos, 2004
I. 2004. Taking trophic cascades up a level: behaviorally-modified effects of phorid flies on ant... more I. 2004. Taking trophic cascades up a level: behaviorally-modified effects of phorid flies on ants and ant prey in coffee agroecosystems. Á/ Oikos 105: 141 Á/147.
Liver Transplantation, 2009
This open-label, randomized study compared the efficacy of a regimen of corticosteroids and tacro... more This open-label, randomized study compared the efficacy of a regimen of corticosteroids and tacrolimus (standard therapy group, n ϭ 79) with a regimen of daclizumab induction therapy in combination with mycophenolate mofetil and tacrolimus (modified therapy group, n ϭ 78) in primary liver transplant recipients. The primary endpoint was biopsy-proven acute rejection (BPAR) at 24 weeks. Secondary endpoints included time to rejection and patient and graft survival. The incidence of BPAR was significantly reduced in the modified therapy group compared to the standard therapy group (11.5% versus 26.6%, respectively, P ϭ 0.017). The time to rejection was significantly shorter in the standard therapy group compared with the modified therapy group (P ϭ 0.044). There was no significant difference between groups in patient or graft survival. Hepatitis C virus-positive patients exhibited no differences from hepatitis C virus-negative patients with respect to the incidence of BPAR. A steroid-sparing regimen of daclizumab, mycophenolate mofetil, and tacrolimus was effective and well tolerated in the prevention of BPAR in adult liver transplant recipients in comparison with a standard regimen of tacrolimus and steroids. Liver Transpl 15:1542-1552, 2009 Standard immunosuppressive therapy after liver transplantation is based on calcineurin inhibitors (CNIs) and corticosteroids. 1 Although corticosteroids are still widely used as maintenance immunosuppression for most liver transplant recipients, tacrolimus has supplanted cyclosporine as the CNI of choice. 1,2 In the United States alone, 89% of liver transplant recipients currently receive ta-crolimus, whereas less than 10% receive cyclosporine. 1 However, both tacrolimus and corticosteroids are associated with serious side effects, including nephrotoxicity (tacrolimus) and hypertension and metabolic effects (corticosteroids). 2 Thus, alternative immunosuppressive regimens that minimize the use of tacrolimus or corticosteroids have been sought.
Gastrointestinal Endoscopy, 2008
Biodiversity and Conservation, 2006
Recent reports show importance of pollinators to coffee and importance of ants as pollinators or ... more Recent reports show importance of pollinators to coffee and importance of ants as pollinators or floral protectors in many systems. Arthropod and pollinator diversity, however, declines with management intensification of coffee (Coffea arabica) agroecosystems. We investigated influences of both flying pollinators and ants on coffee fruit set and fruit weight in one highshade (high-biodiversity) and one low-shade (low-biodiversity) coffee farm in Chiapas, Mexico through exclusion experiments. Contradictory to previous reports, flying pollinators alone did not affect coffee fruit set or fruit weight. Individual fruit weights, however, were higher on branches with both ants and flying pollinators (1.78 g ± 0.312 (SE)) compared to branches without ants (1.03 ± 0.029) or branches without ants or flying pollinators (1.05 ± 0.049), but only in the highshade site. Although the mechanisms producing higher fruit weights are unknown, we discuss how ants or ant-flying pollinator interactions under high-shade coffee management may contribute to increased fruit weight and the implications of high-shade management for both sustainable coffee production and biodiversity conservation.
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Papers by Jorge Maldonado