Plasma antioxidants and human aging: a study on healthy elderly Tunisian population.

The aging has been described by several theories. It was proposed that free radicals are the major factor involved in this process. This gave birth to the free radical theory of aging. This current theory provides the most popular explanation for how aging occurs at the biochemical/molecular level. Ever since 1956, this theory has received widespread attention and a large body of evidence has been accumulated in support of its hypotheses which were subsequently refined. The free radical theory of aging postulates that age-associated reductions in physiological functions are caused by an irreversible accumulation of oxidative alterations to macromolecules. This accumulation increases with age and is associated with the life expectancy of organisms. Moreover, this theory suggests the existence of an imbalance between reactive oxygen species (ROS)-producing pathways and (ROS)-scavenging pathways, which is responsible for the generation of oxidative stress syndrome. In this article, we evaluate the antioxidant status in a population of healthy elderly Tunisians in comparison with a group of healthy young Tunisian subjects. This study sets out to investigate the age-related changes in glutathione peroxidase (GPx), superoxide dismutase (SOD) activities, and in total antioxidant status (TAS) of human plasma. We have concluded that healthy aging is accompanied with a disturbed antioxidant status.

Hormonal status of cortisol and dehydroepiandrosterone sulfate in an elderly Tunisian population.

Adrenal function and aging have been the object of intense interest recently, especially as regards dehydroepiandrosterone sulfate (DHEA-S), which is of major importance, since it is distinct from cortisol and aldosterone in declining with age. In a group of healthy old Tunisians, we investigated the association between cortisol and DHEA-S, on the one hand, and age, sex, lifestyle, physical health, including the body mass index (BMI), physical activity, and smoking indicators, on the other hand. We observed that cortisol concentrations did not change with aging, while DHEA-S concentrations decrease with age in both sexes. Cortisol/DHEA-S ratio, however, increases with aging. Our results revealed that DHEA-S levels are affected neither by physical activity nor by weight. It appears also that current smoking could not affect the level of DHEA-S. Relationships were found between DHEA-S concentrations and BMI, then between DHEA-S levels and serum cholesterol, triglycerides and calcium. No modification in the morning serum cortisol was found to be associated with aging. Decrease in DHEA-S levels is, however, clearly associated with this phenomenon. High cortisol/DHEA-S ratio accelerates the occurrence of some adult diseases, such as diabetes mellitus, atherosclerosis, dementia, and osteoporosis. Generally, the adrenal insufficiency marked by a cognitive impairment, immune disorders, sexual dysfunction, and scores for depression and anxiety can be corrected by a replacement of deficient DHEA-S.

Antibiotic resistance genes detected by multiplex PCR assays in Staphylococcus epidermidis strains isolated from dialysis fluid and needles in a dialysis service.

The rate of the onset of methicillin-resistant Staphylococcus epidermidis infections is increasing in Tunisia. We have isolated 32 S. epidermidis strains from dialysis fluid and needle cultures in dialysis service. The strains were identified by classic methods (colonial morphology, Gram staining, catalase test, coagulase test, and DNase test) as well as by API ID32 Staph. Susceptibilities to 18 antibiotics were tested with the ATB Staph kit. Most of the tested strains were resistant to penicillin. In addition, the presence of multidrug resistant strains that showed resistance to different antibiotics was recorded. We have characterized these strains by multiplex PCR assay to identify intercellular adhesion genes icaA/icaD associated with the adhesiveness of staphylococci in biomaterials, and to identify representative resistant genes: oxacillin resistance, mecA; erythromycin methylase (ermA, ermB, and ermC), and macrolide efflux gene (msrA and mef). The frequency of the carriage of these genes was icaA/icaD (71.9%), mecA (78.1%), ermA (12.5%), ermB (31.3%), ermC (53.1%), msrA (68.8%), and mef (O%). Although the carriage of the genes and the results of susceptibility testing did not match exactly, it could be judged that the PCR identification of antibiotic resistance genes is rapid and supplementary methods for identifying staphylococci or epidemiological study used for the control of nosocomial infection.