Nadia Koubaa

Dietary virgin olive oil protects against lipid peroxidation and improves antioxidant status in the liver of rats chronically exposed to ethanol

Excessive ethanol intake induces severe tissue damage particularly in the liver through the generation of reactive oxygen species. The aim of this study was to determine the effect of a virgin olive oil-rich diet on oxidative stress induced by chronic ethanol exposure in rats. Wistar rats were treated daily with a 35% ethanol solution for 6 weeks and fed with a standard chow or a diet containing 5% virgin olive oil. By administering ethanol to rats, a severe toxicity occurred in their liver, as assessed by the significantly elevated levels of serum transaminases. The hepatic malondialdehyde level, indicator of lipid peroxidation, was also increased in ethanol-treated rats, whereas the hepatic antioxidant enzyme activities, namely, superoxide dismutase, glutathione peroxidase, and catalase were significantly reduced. The activity of glutathione reductase remained unchanged in rats. Fatty acid composition of the liver was also significantly changed with ethanol intake. In contrast, virgin olive oil intake during ethanol treatment in rats resulted in a higher antioxidant activity and inhibited toxicity to the liver, as monitored by the reduction of transaminases levels and hepatic lipid peroxidation. Rats showed a better profile of the antioxidant system with normal glutathione peroxidase activity and ameliorated superoxide dismutase and catalase activities. In conclusion, results of this study indicate that olive oil ingestion by rats protects the liver from ethanol-induced oxidative damage by affecting the cellular redox potential.

Relationship between genetic polymorphisms of angiotensin-converting enzyme and methylenetetrahydrofolate reductase as risk factors for type 2 diabetes in Tunisian patients.

BACKGROUND/AIMS The role of methylenetetrahydrofolate reductase (MTHFR) and angiotensin-converting enzyme (ACE) gene polymorphisms as being risk factors for diabetes is still controversial. The aim was to investigate the distribution of ACE and MTHFR genotypes as well as to evaluate the role of plasmatic total homocysteine levels (tHcy) and ACE activity in Tunisian patients with type 2 diabetes mellitus (T2DM). DESIGN AND METHODS 115 T2DM patients compared to 116 healthy volunteers. RESULTS The ACE I/D polymorphism was significantly associated with diabetes (p<0.0001). The DD genotype and D allele were more frequent in patients compared to control group [DD: OR=4.93; p<0.0001; 95 % CI: 2.71-8.97; D: OR=3.08, 95% CI: 2.09-4.51 p<0.0001]. MTHFR allele and genotype frequencies did not differ between patients and controls. The susceptibility to diabetes in individuals with genotypes DD+vTT was 13.39 and in the individuals with DD+CT was 6.57 times that of the controls. However, individuals with genotypes ID+CC or II+CT have a protective effect against diabetes. The DD and TT genotypes were associated with significantly higher ACE activity and tHcy levels in diabetics. CONCLUSION Our data suggest that ACE ID polymorphism may act synergistically with MTHFR C677T polymorphism to assess diabetes risk.

Association of homocysteine thiolactonase activity and PON1 polymorphisms with the severity of acute coronary syndrome.

INTRODUCTION Excess of total homocysteine (tHcy) and decrease of thiolactonase activities (HTase) have been proposed as risk factors for coronary artery diseases (CAD). OBJECTIVES We evaluated the relationship of tHcy and HTase with paraoxonase 1 (PON1) gene polymorphism according to CAD severity. DESIGN AND METHODS 118 healthy volunteers and 91 CAD patients were compared. RESULTS Serum levels of tHcy and oxidized LDL (ox-LDL) increased significantly by 26% and 48% in CAD patients and were associated with significantly lower levels of HDL cholesterol (p=0.02) and 42% of decrease in HTase activities (p<0.05). In these patients the HTase activity was negatively associated with tHcy and Hs CRP levels (r=-0.622, p=0.00 and r=-0.355, p=0.007 respectively) but positively associated with apoB and triglyceride levels (r=0.35, p=0.042 and r=0.308, p=0.003 respectively). HTase activity decreased inversely to the number of affected vessels and according to PON1 polymorphism. PON1 Q192R RR and PON1 L55M MM genotypes were associated with higher HTase activities. Only PON1 L55M (MM) genotype frequency was significantly higher in CAD patients than in controls (P<0.05), while its frequency was similar between the two subgroups according to CAD severity. In a multivariate analysis, tHcy levels were the only independent factor affecting the severity of cardiovascular disease (p=0.029). CONCLUSIONS High tHcy levels are associated with the severity of cardiovascular disease and may be partly explained by the diminished HTase activities in these patients.

Genotypic interactions of renin-angiotensin system genes with diabetes type 2 in a Tunisian population.

AIMS To explore the role of genetic variants of angiotensinogen (AGT M235T), angiotensin-converting enzyme (ACE I/D), and angiotensin type 1 receptor (AT1R A1166C) as predictors of diabetes risk and to examine their combined effects on type 2 diabetes mellitus (T2DM) patients. MAIN METHODS One hundred and fourteen T2DM patients were compared to 175 healthy controls with similar age and sex. KEY FINDINGS The genotypic frequencies for all three genes alone were significantly associated with increased risk of developing diabetes. Logistic regression analysis of classic coronary risk factors and the genetic polymorphisms demonstrated that hypertension and ACE DD genotype were the most significant contributors to T2DM. For the renin-angiotensin system (RAS) genes, the risk of T2DM in individuals with one risk genotype was 1.9 (95%CI: 1.1-3.0, p=0.017) higher than those with zero risk genotype. Individuals who carried two risk genotypes had a 4.0 (95%CI 1.7-9.4, p=0.001) times higher risk of T2DM than those who did not carry any risk genotypes of the RAS genes. Most interestingly, the risk of T2DM for individuals with three risk genotypes was 26.2 (95%CI: 5.8-117.9, p<0.001) higher than those with zero risk genotype. SIGNIFICANCE The results of the present study imply that genotyping of renin-angiotensin system genes could become an important part of the clinical process of risk identification for T2DM in Tunisian population.

Relationship between thiolactonase activity and hyperhomocysteinemia according to MTHFR gene polymorphism in Tunisian Behçet's disease patients.

Abstract Background: Behçets disease (BD) is a multisystemic immuno-inflammatory disorder. Inflammatory processes may cause lipid peroxidation, alteration of lipid profile and increase the risk of atherosclerosis. The aim of this study was to evaluate the association between thiolactonase (HTLase) activity and plasma homocysteine levels (tHcy) in a BD population and to investigate their association with methylenetetrahydrofolate reductase (MTHFR) 677C→T genotype. Method: A total of 35 BD patients were compared to 39 healthy volunteers. Results: Significantly higher tHcy levels associated with lower HTLase activities were found in BD patients as compared to healthy controls (p<0.001). These patients also exhibited lower values of triglycerides and high-density lipoprotein cholesterol (HDL-C). Homozygosity for the T allele of the MTHFR gene was more frequent in BD patients (14.3% vs. 7.7%). It was associated with significantly higher tHcy levels (16.9 μmol/L for n=17 vs. 13.1 μmol/L for n=18; p<0.05) and markedly lower HTLase activity (362.6±156.7 U/L vs. 414.2±180.2 U/L) for the (TT+CT) and CC genotypes, respectively. Moreover, HDL-C levels were inversely correlated with tHcy (r=–0.5; p=0.004) but positively associated with HTLase activity (r=0.374; p=0.038). These correlations were also present in several clinical manifestations, such as ocular, neurological involvement or thrombosis. Conclusions: Homozygosity of the T allele of the MTHFR gene is prevalent in BD patients. High levels of tHcy associated with low HTLase activities may be one of the causes leading to thrombosis in BD patients. Clin Chem Lab Med 2008;46:187–92.

Prevalence of diabetes mellitus among non institutionalized elderly in Monastir City

BackgroundDiabetes is a major public health problem worldwide. This problem is particularly relevant to the elderly. The prevalence of each condition increase with age. The present study aimed to determine the prevalence of Diabetes Mellitus (DM) among elderly; we also examined socio-economic factors and life style that are likely to be associated with DM.MethodsA cross-sectional study was conducted in 2008–2009, and used a multistage cluster sampling method to select a representative sample among non institutionalized elderly in Monastir City. A total of 598 elderly aged 65 to 95 years were included.ResultsThe prevalence of DM was 27.4% (29.2% in males’ vs 26.5% in females). Elderly with DM showed higher prevalence of hypertension, obesity and abdominal obesity. DM prevalence decreased with advancing ages in both men and women. Urban residents had a higher prevalence than did their rural counterparts. In multivariate analysis, DM was associated with abdominal obesity (OR [95% CI], 2.6 [1.1-6]; p <0.01), co-existing diseases (3.8 [2.4-6]; p <0.01), and hypertension (2.7 [1.6-4.5] ; p <0.01).ConclusionThe study highlights the DM problem in Tunisia. An ageing population together with social, economic and lifestyle changes have led to a dramatic increase in DM. These data emphasize the urgent need for a comprehensive integrated population-based intervention program to ameliorate the growing problem of DM.

Awareness, treatment and control of hypertension among the elderly living in their home in Tunisia

BackgroundHypertension is a cardiovascular disorder rapidly emerging as a major public health problem in developing countries. However, the acknowledgement of the prevalence and the significant impact of hypertension in elderly are very important for health policy. The objective of the present investigation was to evaluate the prevalence, awareness and treatment of hypertension among the elderly living in their home in Tunisia at Monastir City. We also examined the impact of socio-demographic characteristics and known risk factors for high blood pressure.MethodsA community based sample of 598 non-institutionalized elderly (age ≥ 65 years), was selected using probabilistic multistage cluster sampling.ResultsThere was a predominance of female (66%) and mean age was 72.3 ± 7.4 years. The prevalence of hypertension was 52% (n = 311), awareness (81%, n = 252), treatment (78.4%, n = 244) and only 30.7% (n = 75) are correctly treated. The prevalence of hypertension was higher for the female population (55.5%) when compared to males (45%). No urban/rural differences were observed and no difference was observed by educational level. Multiple logistic regression analyses identified a higher body mass index, diabetes mellitus and disability as important correlates of the prevalence of hypertension.ConclusionThese findings provide important information on the prevalence, awareness and control of hypertension in Monastir City and confirm their association with other cardio-vascular risk factors. Effective public health measures and strategies are needed to improve prevention, diagnosis and access to treatment of this elderly population.

Association of the C677T MTHFR Polymorphism With Homocysteine, Ox-LDL Levels, and Thiolactonase Activities in the Severity of Coronary Syndrome

Coronary artery diseases (CAD) are influenced by multiple genes of modest effect as the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism, related to MTHFR activity and total plasma homocysteine (tHcy) concentration. This study was designed to evaluate tHcy, oxidized low-density lipoprotein (LDL) (ox-LDL), high-sensibility C-reactive protein (Hs CRP) levels, and homocysteine thiolactonase (HTase) activities as new risk factors for CAD and to investigate an association between MTHFR polymorphism tHcy concentrations and coronary syndrome severity. Our results showed significantly higher levels of tHcy and ox-LDL in patients associated with lower HTase activities. These levels increased proportionally to disease severity. Total plasma Hcy levels were negatively correlated to HTase activities in patients where the TT genotype was significantly more frequent. In a multivariate analysis, tHcy level was the only independent factor affecting the coronary syndrome severity. High tHcy levels are associated with coronary syndrome severity and may be explained either by the elevated prevalence of TT genotype or by the diminished HTase activities.

Identification of long and very long chain fatty acids, plasmalogen-C16:0 and phytanic acid as new lipid biomarkers in Tunisian coronary artery disease patients

Long and very long chain fatty acids (LCFAs and VLCFAs) may play an active role in coronary artery diseases (CAD) etiology. Our aim was to evaluate the associations between LCPUFAs (C20:4n-6; C20:5n-3 and C22:6n-3) and VLCSFAs (C22:0, C24:0; and C26:0), as well as markers of peroxisomal integrity evaluated by phytanic acid and plasmalogen-C16:0 (PL-C16:0) in addition to the markers of lipid peroxidation (malondialdehyde [MDA] and conjugated dienes [CD]) and inflammation (high sensitivity C-reactive protein [hs-CRP]) with vascular severity evaluated by Gensini score in order to determine their possible effects on CAD in Tunisian population. Lipidomic strategy based on GC/MS-SIM was used to quantify LCPUFAs, VLCSFAs, and PL-C16:0 in red blood cells of CAD patients, non-CAD patients, and controls. We observed a significant increase in phytanic acid, PL-C16:0 and VLCFAs, particularly C26:0, in CAD group compared to controls. Further our findings showed positive correlations of C26:0 with MDA and with vascular severity score (Gensini score). In addition, a significant negative correlation was shown between hs-CRP and C22:6 n-3 (r=-0.297; p=0.002) and a significant positive association was observed between hs-CRP and C20:4 n-6 levels (r=0.196; p=0.039). Our results show changes in LCPUFAs and VLCSFAs concentrations in RBC among study groups, and suggest alterations in fatty acids metabolism regulated by elongase and desaturase enzymes. The positive correlations of C20:4n-6 and the negative correlations of C22:6n-3, simultaneously with Gensini score and hs-CRP, suggest a link of both inflammation and vascular severity complication of CAD with LCPUFAs and VLCSFAs. Induction of lipid oxidation, can be one of the outcomes of LCFAs and VLCFAs accumulation in vascular tissues and, thus, playing an important role in the pathogenesis of atherosclerosis. Quantification of LCPUFAs and VLCSFAs, phytanic acid and PL-C16:0 simultaneously, would be of great value for the screening of peroxisomal disorders in vascular tissue of CAD patients.

0143: Serum thiolactonase activity and paraoxonase gene polymorphism in coronary artery Tunisian patients with or without diabetes

Serum homocysteine thiolactonase activity is closely related to homocysteine and ox-LDL levels in coronary artery disease patients. Homocysteine thiolactonase activities are the result of environmental factors and genetic polymorphisms of paroxosonase. The relevance of gene polymorphism in coronary patients with or without diabetes was investigated in a case-control study. Methods The population included 140 control subjects, 47 coronary artery disease patient without diabetes and 44 patients with type 2 diabetes. Results Serum thiolactonase activity decreased significantly in coronary artery disease patients: 318.9±156 U/l those without diabetes and 388.8±180 in the diabetic ones compared with the controls: 568.8±250U/l (p Conclusions The difference in allele frequency for the paroxonase R gene polymorphism may be the cause of the high thiolactonase activity observed in coronary patients with type 2 diabetes mellitus. Further studies are needed to be conducted to elucidate the role of the enzyme in the development of vascular complications in these patients.