Effect of noradrenaline on propofol-induced mitochondrial dysfunction in human skeletal muscle cells.

BACKGROUND: Mitochondrial dysfunction is a hallmark of both critical illness and propofol infusion syndrome and its severity seems to be proportional to the doses of noradrenaline, which patients are receiving. We comprehensively studied the effects of noradrenaline on cellular bioenergetics and mitochondrial biology in human skeletal muscle cells with and without propofol-induced mitochondrial dysfunction. METHODS: Human skeletal muscle cells were isolated from vastus lateralis biopsies from patients undergoing elective hip replacement surgery (n = 14) or healthy volunteers (n = 4). After long-term (96 h) exposure to propofol (10 µg/mL), noradrenaline (100 µM), or both, energy metabolism was assessed by extracellular flux analysis and substrate oxidation assays using [14C] palmitic and [14C(U)] lactic acid. Mitochondrial membrane potential, morphology and reactive oxygen species production were analysed by confocal laser scanning microscopy. Mitochondrial mass was assessed both spectrophotometrically and by confocal laser scanning microscopy. RESULTS: Propofol moderately reduced mitochondrial mass and induced bioenergetic dysfunction, such as a reduction of maximum electron transfer chain capacity, ATP synthesis and profound inhibition of exogenous fatty acid oxidation. Noradrenaline exposure increased mitochondrial network size and turnover in both propofol treated and untreated cells as apparent from increased co-localization with lysosomes. After adjustment to mitochondrial mass, noradrenaline did not affect mitochondrial functional parameters in naïve cells, but it significantly reduced the degree of mitochondrial dysfunction induced by propofol co-exposure. The fatty acid oxidation capacity was restored almost completely by noradrenaline co-exposure, most likely due to restoration of the capacity to transfer long-chain fatty acid to mitochondria. Both propofol and noradrenaline reduced mitochondrial membrane potential and increased reactive oxygen species production, but their effects were not additive. CONCLUSIONS: Noradrenaline prevents rather than aggravates propofol-induced impairment of mitochondrial functions in human skeletal muscle cells. Its effects on bioenergetic dysfunctions of other origins, such as sepsis, remain to be demonstrated.

Burn-Induced Cardiac Dysfunction: A Brief Review and Long-Term Consequences for Cardiologists in Clinical Practice.

BACKGROUND: Severe burn injury is a specific type of trauma, which induces a unique complex of responses in the body and leads to an extreme increase in stress hormones and proinflammatory cytokines. These hypermetabolic and stress responses are desirable in the acute phase but can persist for several years and lead - due to several mechanisms - to many late complications, including myocardial dysfunction. METHODS: The databases of PubMed, ScienceDirect, National Institutes of Health (NIH) of the United States, and Google Scholar were searched. Studies relevant to the topic of late cardiovascular dysfunction after burn injury were compiled using key words. RESULTS: Burn-induced heart disease significantly increases morbidity and mortality and contributes to the reduction in the quality of life of patients after severe burn trauma. A variety of mechanisms causing myocardial dysfunction after burn trauma have been detailed but understanding all of the exact consequences is limited, especially regarding chronic cardiovascular changes. CONCLUSION: A detailed understanding of the pathophysiology of chronic cardiac changes can contribute to a comprehensive and preventive treatment plan and improve long-term outcomes of burn patients.

Parenterally administered dipeptide alanyl-glutamine prevents worsening of insulin sensitivity in multiple-trauma patients.

BACKGROUND: Dipeptide alanyl-glutamine is a commonly used substrate in major trauma patients. Its importance and effects are widely discussed; as yet, it has not been elucidated whether its administration influences glucose homeostasis. OBJECTIVE: We studied the effect of alanyl-glutamine administration on insulin resistance. DESIGN: Prospective, randomized, controlled trial. SETTING: Intensive care unit of a tertiary level hospital. PATIENTS: Multiple-trauma patients. INTERVENTIONS: Patients were randomized into two groups and assigned to receive parenterally an equal dose of amino acids either with alanyl-glutamine in the dose of 0.4 g x kg body weight(-1) x 24 hrs(-1) (group AG) or without alanyl-glutamine (control group C). This regimen started 24 hrs after injury and continued for 7 days. To assess insulin sensitivity, we performed an euglycemic clamp on day 4 and day 8 after injury. MEASUREMENTS AND MAIN RESULTS: We randomized 40 patients, 20 into each group. At day 4, insulin-mediated glucose disposal was higher in group AG (2.4 +/- 0.7 mg x kg(-1) x min(-1) glucose), with significant difference from group C (1.9 +/- 0.6 mg x kg(-1) x min(-1), p = .044). At day 8, glucose disposal was higher in group AG (2.2 +/- 0.7 mg x kg(-1) x min(-1) glucose), with significant difference in comparison with group C (1.2 +/- 0.6, p < .001). Diminution of the main glucose homeostasis variables in group C between days 4 and 8 of the study was statistically significant (p < .001); however, differences in these variables in group AG were without statistical significance. CONCLUSIONS: Parenteral supplementation of alanyl-glutamine dipeptide was associated with better insulin sensitivity in multiple-trauma patients.

Changes in cholesterol and its precursors during the first days after major trauma.

BACKGROUND: The causes of hypocholesterolemia in the critically ill, including major trauma patients, have not yet been fully elucidated. OBJECTIVE: We tested the hypothesis that hypocholesterolemia is caused by decreased production of cholesterol precursors. DESIGN: Serum concentrations of squalene, lanosterol, and lathosterol were measured on admission, and then at 24 and 48 hours after injury using gas chromatography coupled with mass spectrometry. Serum concentrations of total low-density and high-density lipoprotein cholesterol were measured on admission and every day in the first week after injury. RESULTS: 83 consecutive patients with multiple trauma were examined. Significant drops in concentrations of lanosterol and lathosterol were found in the patients in comparison with the control group. The most profound drop was in lathosterol. CONCLUSION: Decreased synthesis of cholesterol precursors is the major cause of hypocholesterolemia in patients with multiple trauma. Lathosterol concentration is proposed as a marker of cholesterol synthesis.