BackgroundThe presence of resistant bacteria in the oral cavity can be the major cause of dental antibiotic prophylaxis failure. Multidrug efflux has been described for many organisms, including bacteria and fungi as part of their drugs resistance strategy. The discovery of a new efflux pump inhibitor could extend the useful lifetime of some antibiotics.MethodsIn this study, the MICs of thymoquinone (TQ), tetracycline and benzalkonium chloride (BC) were determined in absence and in presence of a sub-MIC doses of thymoquinone (1/2 MIC). In addition the 4,6-diamidino-2-phenylindole (DAPI) efflux assay was carried out to determine the effect of TQ on DAPI cells accumulation.ResultsTQ induced a selective antimicrobial activity. Its synergic effect resulted in at least a 4-fold potentiation of the tested antibiotics and antiseptic. In addition, TQ inhibited the DAPI efflux activity in a concentration-dependent manner. The rate of DAPI accumulation in clinical isolates was enhanced with TQ (0 to 200 μg/ml). There is also a decrease in loss of DAPI from bacteria in the presence of TQ. The concentration causing 50% of DAPI efflux inhibition after 15 minutes was approximately 59 μg/ml for Pseudomonas aeroginosa and 100 μg/ml and Staphylococcus aureus respectively.ConclusionsTQ possesses a selective antibacterial activity against oral bacteria. It is therefore suggested that TQ could be used as a source of natural products with resistance-modifying activity. Further investigation is needed to assess their clinical relevance.
BackgroundDisturbance of the equilibrium between reactive oxygen species (ROS) and anti-oxidants (AOX) has been implicated in various diseases, including atherosclerosis, the most common pathologic process underlying coronary heart disease (CHD). Thus, the defense systems against ROS are critical protecting blood vessel walls against oxidative damage. In this study, we investigate whether Ala16Val MnSOD and Pro198Leu GPx polymorphisms are associated with CHD susceptibility and/or severity.MethodsBoth polymorphisms were genotyped in a sample of 203 controls and 164 patients. CHD risk and severity, antioxidant status (enzymatic and/or non enzymatic) and biochemical parameters were assessed and analysed by genotype.ResultsA significant association of MnSOD variant to CHD risk was revealed in males. Males harboring the Val/Val genotype were approximately at twofold increased risk of CHD compared to controls (Ala carriers vs Val/Val, adjusted OR 1.89; 95 % CI 1.18‒3.42, p = 0.03). Significant decreases in SOD activity and total antioxidant status (TAS) were observed in Val carriers and by CHD status. Whereas, no association of GPx variant genotype (Leu/Leu) and activity to cardiopathy events was discerned. CHD severity, as demonstrated by the number of vessel stenosis, was associated with significantly higher frequency of Val allele and LDL levels in CHD subjects.ConclusionsOur results showed a lack of association of Pro198Leu GPx polymorphism to CHD risk and severity. However, they suggest that Ala16Val MnSOD polymorphism and decreased antioxidant defences are likely contributed to CHD risk in Tunisian men. Furthermore, the Val encoding MnSOD allele and decreased SOD activity were significantly correlated with CHD stenosis progression.
Barley Yellow Dwarf (BYD) is a serious Luteovirus disease that affects small grain production worldwide. The aphid-transmitted virus (BYDV) infects practically all members of the Graminae (Poaceae) and is responsible for serious losses in cultivated species such as barley, wheat and oats. The study of BYD is complex, as it involves interactions among a vector, a plant and a virus. Hence, symptom expression is highly dependent on environmental conditions, serotypes plant genetic background and physiological stage of inoculation. Consequently, tolerance to BYDV is also difficult to study and understand. This review explores the basic biology of BYD, its symptoms, its viruses and yield losses it can cause.
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