Michal Anděl

Genetic variants of homocysteine metabolizing enzymes and the risk of coronary artery disease.

It is unresolved whether elevated homocysteine in coronary artery disease (CAD) is the cause of arteriosclerosis or its consequence. In contrast, genetic variants of enzymes that metabolize homocysteine cannot be altered by arteriosclerosis. Consequently, their association with CAD would permit to imply causality. We modeled by regression analysis the effect of 11 variants in the methionine cycle upon CAD manifestation in 591 controls and 278 CAD patients. Among the examined variants only the carriership for the c.844ins68 in the cystathionine beta-synthase (CBS) gene was associated with a significantly lowered risk of CAD (OR=0.56; 95% CI=0.35-0.90 in the univariable, and OR=0.41, 95% CI=0.19-0.89 for obese people in the multivariable analysis, respectively). Healthy carriers of the c.844ins68 variant exhibited, compared to the wild type controls, significantly higher postload ratios of blood S-adenosylmethionine to S-adenosylhomocysteine (61.4 vs. 54.9, p=0.001) and of plasma total cysteine to homocysteine (8.6 vs. 7.3, p=0.004). The changes in these metabolites are compatible with an improved methylation status and with enhanced activity of homocysteine transsulfuration. In conclusion, the coincidence of clinical and biochemical effects of a common c.844ins68 CBS variant supports the hypothesis that compounds relating to homocysteine metabolism may play role in the development and/or progression of CAD.

Frequent intravenous pulses of growth hormone together with glutamine supplementation in prolonged critical illness after multiple trauma: Effects on nitrogen balance, insulin resistance, and substrate oxidation*

Objectives:To estimate the efficacy and metabolic effects of growth hormone substitution as intravenous pulses together with alanyl-glutamine supplementation and tight blood glucose control in prolonged critical illness. Design:Prospective double-blind, randomized trial with open-label control arm. Setting:Intensive care unit of tertiary level hospital. Patients:Thirty multiple trauma patients (median Injury Severity Score 34). Interventions:Patients were randomized, at day 4 after trauma, to receive intravenous alanyl-glutamine supplementation (0.3 g/kg·day−1 from day 4 until day 17) and intravenous growth hormone (administered days 7–17, full dose 50 &mgr;g/kg·day−1 from day 10 onward) (group 1, n = 10) or alanyl-glutamine and placebo (group 2, n = 10). Group 3 (n = 10) received isocaloric isonitrogenous nutrition (proteins 1.5 g/kg·day−1) without alanyl-glutamine. Measurements and Main Results:Cumulative nitrogen balance for the whole study period was −97 ± 38 g of nitrogen for group 1, −193 ± 50 g of nitrogen for group 2, and −198 ± 77 g of nitrogen for group 3 (p < .001). This represents a daily saving of 300 g of lean body mass in group 1. Insulin-mediated glucose disposal, during euglycemic clamp, as a measure of insulin sensitivity, significantly worsened between days 4 and 17 in group 1 but improved in groups 2 and 3. Group 1 required significantly more insulin to control blood glucose, resulting in higher insulinemia (∼70 mIU in group 1 vs. ∼25 mIU in groups 2 and 3). Despite this, growth hormone treatment caused an increase in plasma nonesterified fatty acid (∼0.5–0.6 mM in group 1 in comparison with ∼0.2–0.3 mM in groups 2 and 3) but did not influence lipid oxidation. There were no differences in morbidity, mortality, or 6-month outcome among the groups. Conclusions:Treatment with frequent intravenous pulses of low-dose growth hormone together with alanyl-glutamine supplementation improves nitrogen economy in patients with prolonged critical illness after multiple trauma but worsens insulin sensitivity. Tight blood glucose control is possible but requires higher doses of insulin.

Lipophilic Triphenylphosphonium Cations Inhibit Mitochondrial Electron Transport Chain and Induce Mitochondrial Proton Leak

Background The lipophilic positively charged moiety of triphenylphosphonium (TPP+) has been used to target a range of biologically active compounds including antioxidants, spin-traps and other probes into mitochondria. The moiety itself, while often considered biologically inert, appears to influence mitochondrial metabolism. Methodology/Principal Findings We used the Seahorse XF flux analyzer to measure the effect of a range of alkylTPP+ on cellular respiration and further analyzed their effect on mitochondrial membrane potential and the activity of respiratory complexes. We found that the ability of alkylTPP+ to inhibit the respiratory chain and decrease the mitochondrial membrane potential increases with the length of the alkyl chain suggesting that hydrophobicity is an important determinant of toxicity. Conclusions/Significance More hydrophobic TPP+ derivatives can be expected to have a negative impact on mitochondrial membrane potential and respiratory chain activity in addition to the effect of the biologically active moiety attached to them. Using shorter linker chains or adding hydrophilic functional groups may provide a means to decrease this negative effect.

Health Behaviors, Nutritional Status, and Anthropometric Parameters of Roma and Non-Roma Mothers and Their Infants in the Czech Republic

OBJECTIVE To compare maternal health behaviors, maternal nutritional status, and infant size at birth of Romas and non-Romas in the Czech Republic. DESIGN Maternal interviews and food frequency questionnaire, maternal blood samples, physical measurements of mothers and infants. SETTING Hospital, maternal/child care center; 2-4 days postpartum. PARTICIPANTS 76 Roma mothers and 151 mothers from the majority population. MAIN OUTCOME MEASURES Infant length/weight; maternal height/weight; weight gain during pregnancy; duration of pregnancy; maternal smoking habits; dietary intake; use of food supplements during pregnancy; and maternal blood levels of folate, beta-carotene, retinol, and alpha-tocopherol. ANALYSIS Comparison of ethnic groups by 2-sample Wilcoxon test, chi-square, Fischers exact test, relative risk, and analysis of variance (ANOVA). RESULTS Pregnancy duration was about 1 week shorter in Roma women (P < .001), and their infants had lower birth weight (P < .001) and shorter length (P < .001). Prevalence of smoking was significantly higher among Roma mothers (P < .001). Roma women used food supplements less frequently than non-Roma women (P < .001) and had significantly lower mean blood concentrations of folate (P < .001), beta-carotene (P < .001), retinol (P < .02), and alpha-tocopherol (P < .02). CONCLUSIONS AND IMPLICATIONS The nutritional status of Roma mothers is worse than that of mothers from the majority Czech population. The dietary and smoking habits of pregnant Roma women should be of special concern to family doctors, obstetricians, nutrition educators, and social workers.

Palmitate-Induced Cell Death and Mitochondrial Respiratory Dysfunction in Myoblasts are Not Prevented by Mitochondria-Targeted Antioxidants

Background/Aims: Deleterious effects of saturated fatty acids in skeletal muscle cells are well known but their impact on mitochondrial respiration has not been well studied. Mitochondrial oxidative damage has been implicated to play a role in their effect. The purpose of this study was to evaluate viability, mtDNA integrity and mitochondrial respiration in C2C12 myoblasts and myotubes exposed to palmitate and to test the effect of mitochondria-targeted antioxidants MitoQ and MitoTEMPOL in preventing palmitate-induced damage. Methods: Cells were treated with tested compounds, mtDNA damage was detected by quantitative PCR and mitochondrial respiration was measured using an extracellular flux analyzer XF24. Results: Palmitate caused mtDNA damage, which was associated with reduced mitochondrial respiration and cell death in myoblasts but not in myotubes. MitoTEMPOL was able to prevent palmitate-induced mtDNA damage in myoblasts but failed to prevent cell death. MitoQ did not show any protective effect and both compounds markedly inhibited mitochondrial respiration. Conclusion: Our results indicate that skeletal muscle progenitor cells could be the first target of the deleterious action of palmitate, as myoblasts appeared to be more sensitive to its effects than myotubes possibly in part due to a lower spare respiratory capacity in the former. Only MitoTEMPOL prevented palmitate-induced mtDNA damage but neither antioxidant was able to prevent cell death and both antioxidants had a marked negative effect on respiration.

Low Glucose but Not Galactose Enhances Oxidative Mitochondrial Metabolism in C2C12 Myoblasts and Myotubes

Background Substituting galactose for glucose in cell culture media has been suggested to enhance mitochondrial metabolism in a variety of cell lines. We studied the effects of carbohydrate availability on growth, differentiation and metabolism of C2C12 myoblasts and myotubes. Methodology/Principal Findings We measured growth rates, ability to differentiate, citrate synthase and respiratory chain activities and several parameters of mitochondrial respiration in C2C12 cells grown in media with varying carbohydrate availability (5 g/l glucose, 1 g/l glucose, 1 g/l galactose, and no added carbohydrates). C2C12 myoblasts grow more slowly without glucose irrespective of the presence of galactose, which is not consumed by the cells, and they fail to differentiate without glucose in the medium. Cells grown in a no-glucose medium (with or without galactose) have lower maximal respiration and spare respiratory capacity than cells grown in the presence of glucose. However, increasing glucose concentration above physiological levels decreases the achievable maximal respiration. C2C12 myotubes differentiated at a high glucose concentration showed higher dependency on oxidative respiration under basal conditions but had lower maximal and spare respiratory capacity when compared to cells differentiated under low glucose condition. Citrate synthase activity or mitochondrial yield were not significantly affected by changes in the available substrate concentration but a trend towards a higher respiratory chain activity was observed at reduced glucose levels. Conclusions/Significance Our results show that using galactose to increase oxidative metabolism may not be applicable to every cell line, and the changes in mitochondrial respiratory parameters associated with treating cells with galactose are mainly due to glucose deprivation. Moderate concentrations of glucose (1 g/l) in a growth medium are optimal for mitochondrial respiration in C2C12 cell line while supraphysiological concentrations of glucose cause mitochondrial dysfunction in C2C12 myoblasts and myotubes.

Intensive blood glucose control in acute and prolonged critical illness: endogenous secretion contributes more to plasma insulin than exogenous insulin infusion.

We investigated the contribution of impaired insulin secretion (observed as dynamics of C-peptide) and insulin resistance (measured by euglycemic clamps) to glucose dysregulation in 20 critically ill patients after severe trauma during feeding and intensive glucose control with intravenous insulin. Between the fourth and seventh day when insulin sensitivity is lowest, insulin secretion is highest and supranormal despite tight control of blood glucose by exogenous insulin. Afterward, plasma C-peptide decreases together with an improvement in insulin sensitivity. Multiple regression analysis revealed that plasma insulin is determined more by endogenous secretion than insulin infusion, even during the acute phase when exogenous insulin requirements are high.

Higher insulin sensitivity in vegans is not associated with higher mitochondrial density

BACKGROUND/OBJECTIVES:Vegans have a lower incidence of insulin resistance (IR)-associated diseases and a higher insulin sensitivity (IS) compared with omnivores. The aim of this study was to examine whether the higher IS in vegans relates to markers of mitochondrial biogenesis and to intramyocellular lipid (IMCL) content.SUBJECTS/METHODS:Eleven vegans and 10 matched (race, age, sex, body mass index, physical activity and energy intake) omnivorous controls were enrolled in a case–control study. Anthropometry, bioimpedance (BIA), ultrasound measurement of visceral and subcutaneous fat layer, parameters of glucose and lipid homeostasis, hyperinsulinemic euglycemic clamp and muscle biopsies were performed. Citrate synthase (CS) activity, mitochondrial DNA (mtDNA) and IMCL content were assessed in skeletal muscle samples.RESULTS:Both groups were comparable in anthropometric and BIA parameters, physical activity and protein–energy intake. Vegans had significantly higher glucose disposal (M-value, vegans 8.11±1.51 vs controls 6.31±1.57 mg/kg/min, 95% confidence interval: 0.402 to 3.212, P=0.014), slightly lower IMCL content (vegans 13.91 (7.8 to 44.0) vs controls 17.36 (12.4 to 78.5) mg/g of muscle, 95% confidence interval: −7.594 to 24.550, P=0.193) and slightly higher relative muscle mtDNA amount (vegans 1.36±0.31 vs controls 1.13±0.36, 95% confidence interval:−0.078 to 0.537, P=0.135). No significant differences were found in CS activity (vegans 18.43±5.05 vs controls 18.16±5.41 μmol/g/min, 95% confidence interval: −4.503 to 5.050, P=0.906).Conclusions:Vegans have a higher IS, but comparable mitochondrial density and IMCL content with omnivores. This suggests that a decrease in whole-body glucose disposal may precede muscle lipid accumulation and mitochondrial dysfunction in IR development.

Nutritional Status Assessment of Institutionalized Elderly in Prague, Czech Republic

Background: There are few studies in the Czech Republic describing and evaluating the nutritional status of institutionalized elderly. Methods: Data were collected from 659 women and 156 men aged 65 years and older and living in retirement homes in and around Prague. Data included: a Mini-Nutritional Assessment (MNA questionnaire), anthropometric measurements and biochemical evaluations. Results: According to the MNA questionnaire, 10.2% of these elderly individuals were malnourished and 39.4% were at risk of malnutrition. More women than men were malnourished (OR = 0.59 and 95% CI 0.42-0.86). Mean BMI values were 25.5 for females and 27.5 for males. MNA was positively correlated mostly with immobility (r = 0.63; p < 0.001), BMI (r = 0.57; p < 0.001) and mid-arm circumference (r = 0.56; p < 0.001). Serum albumin levels were <28 g/l in 1.3% (1.3% of the women and 1.36% of the men) and between 29.0 - 34.0 g/l in 21% (22.5% of the women and 14.4% of the men). Statistically significant differences between groups according to MNA scores were found for albumin, prealbumin, transferrin and creatinine. Prevalence of smoking was significantly higher among males. Conclusion: The study results confirmed that institutionalized elderly, especially women, should be considered a nutritionally vulnerable population group that needs attention.

Short-Term Dietary Intake of C18:1 Trans Fatty Acids Decreases the Function of Cellular Immunity in Healthy Young Men

Aim: In this study, we tested the impact of short-term intake of increased amounts of C18:1 trans fatty acids (TFAs) on parameters of cellular and humoral immunity in healthy young men. Methods: Twenty-seven healthy young men were subsequently exposed to a standard diet for 7 days and an experimental TFA-enriched diet for 4 days. The mean energy content of these diets was 2,453 and 2,455 kcal/day, with 10, 35 and 55% of energy from proteins, fats and carbohydrates, respectively. Standard diet contained about 0.8 g and experimental diet 10.4 g TFAs. Plasma levels of C18:1 TFAs and immunological parameters were measured. Results: The 4-day increased consumption of C18:1 TFAs led to a significant decrease in mitogen-induced CD69 expression on CD8+ T cells as well as decreased phagocytic activity on neutrophils. After returning to the participants’ habitual diet (1 week after the end of the experimental diet), we observed a significant decrease in the mean level of circulating immune complexes. Concentrations of plasma immunoglobulins remained unchanged throughout the study. Conclusions: Acute impact of higher dietary C18:1 TFA intake on phagocytosis and cell-mediated immunity seems to be suppressive. This finding differs from results describing proinflammatory effects associated with long-term exposure to TFAs.