Transcriptomic approach and membrane fatty acid analysis to study the response mechanisms of Escherichia coli to thyme essential oil, carvacrol, 2-(E)-hexanal and citral exposure.

AIMS: The application of essential oils (EOs) and their components as food preservatives is promising but requires a deeper understanding of their mechanisms of action. This study aims to evaluate the effects of thyme EO, carvacrol, citral and 2-(E)-hexenal, on whole-genome gene expression (the transcriptome), as well as the fatty acid (FA) composition of the cell membranes of Escherichia coli K12. METHODS AND RESULTS: Therefore, we studied the response against 1 h of exposure to sublethal concentrations of natural antimicrobials, of exponentially growing E. coli K12, using DNA microarray technology and a gas chromatographic method. The results show that treatment with a sublethal concentration of the antimicrobials strongly affects global gene expression in E. coli for all antimicrobials used. Major changes in the expression of genes involved in metabolic pathways as well as in FA biosynthesis and protection against oxidative stress were evidenced. Moreover, the sublethal treatments resulted in increased levels of unsaturated and cyclic FAs as well as an increase in the chain length compared to the controls. CONCLUSIONS: The down-regulation of genes involved in aerobic metabolism indicates a shift from respiration to fermentative growth. Moreover, the results obtained suggest that the cytoplasmic membrane of E. coli is the major cellular target of EOs and their components. In addition, the key role of membrane unsaturated FAs in the response mechanisms of E. coli to natural antimicrobials has been confirmed in this study. SIGNIFICANCE AND IMPACT OF THE STUDY: The transcriptomic data obtained signify a further step to understand the mechanisms of action of natural antimicrobials also when sublethal concentrations and short-term exposure. In addition, this research goes in deep correlating the transcriptomic modification with the changes in E. coli FA composition of cell membrane identified as the main target of the natural antimicrobials.

Influence of climatic variables on acute myocardial infarction hospital admissions.

BACKGROUND: Seasonal peaks in acute myocardial infarction (AMI) incidence have been widely reported. Weather has been postulated to be one of the elements at the basis of this association. The aim of our study was to determine the influence of seasonal variations and weather on AMI hospital admissions. METHODS: We correlated the daily number of AMI cases admitted to a western Sicily hospital over twelve years and weather conditions on a day-to-day basis. Information on temperature, humidity, wind force and direction, precipitation, sunny hours and atmospheric pressure was obtained from the local Birgi Air Force base. A total of 3918 consecutive patients were admitted with AMI over the period 1987-1998 (2822 men, 1096 women; M/F: 2,58). RESULTS AND CONCLUSIONS: A seasonal variation was found with a significant winter peak. The results of multivariate Poisson analysis show in both sexes a significant association as regards the incidence relative ratio between the daily number of AMI hospital admission and minimal daily temperature and maximal daily humidity. The incidence relative ratios (95% confidence intervals) were, in males, 0.95 (0.92-0.98) (p<0.001) as regards minimal temperature and 0.97 (0.94-0.99) (p=0.017) as regards maximal humidity. The corresponding values in females were respectively 0.91 (0.86-0.95) (p<0.001) and 0.94 (0.90-0.98) (p=0.009). Environmental temperature, and also humidity, may play an important role in the pathogenesis of AMI. These data may help in understanding the mechanisms whereby AMI events are triggered and in organizing better the assistance to ischemic patients throughout the year.

Increased plasma levels of fibrinogen in acute and chronic ischemic coronary syndromes.

BACKGROUND: The aim of this study was to evaluate the pathophysiological role of fibrinogen in patients with chronic or acute ischemic coronary syndromes on the basis of epidemiological and clinical evidences showing the importance of fibrinogen as a risk factor for cardiovascular diseases and atherosclerosis progression. METHODS: We evaluated the behavior of plasma fibrinogen in 310 hospitalized patients with 1) acute myocardial infarction (n = 98); 2) unstable angina (n = 87); 3) chronic ischemic heart disease (n = 75); and 4) in controls without myocardial ischemia (n = 50). Fibrinogen was evaluated, by using the Clauss method, on day 1 and 5 during in hospital-stay and at 6-month follow-up in patients suffering from acute myocardial infarction. RESULTS: Plasma levels of fibrinogen were higher in patients with chronic ischemic heart disease (335.3 +/- 81.2 mg/dl, p < 0.001) and especially in patients with acute myocardial infarction (454.72 +/- 69.5 mg/dl, p < 0.00001) and unstable angina (382.6 +/- 101.3 mg/dl, p < 0.00025) in comparison with controls (271.28 +/- 62.4 mg/dl). Q wave myocardial infarction showed higher levels of fibrinogen than non-Q wave (461.3 +/- 95.8 vs 422.5 +/- 71.3 mg/dl, p < 0.02). Patients with acute myocardial infarction showed a further increase in fibrinogen on day 5 in comparison with entry levels (525.88 +/- 87.3 vs 454.7 +/- 69.5 mg/dl, p < 0.00001) regardless of the fibrinolytic treatment. Patients who died (n = 6) or had severe arrhythmias (n = 4) during in-hospital stay as well as those with post-infarction angina (n = 20) showed higher fibrinogen levels. CONCLUSIONS: Our results confirm the role of fibrinogen as a risk factor for ischemic heart disease, especially in patients with unstable angina and acute myocardial infarction. In the latter, elevated fibrinogen values seem also to be associated with a worsen prognosis during hospitalization.