In Vitro Assessment of Cytotoxicity and Estrogenicity of Vivera® Retainers.

AIM: To investigate the cytotoxicity and estrogenicity of Vivera® retainers by assessing their biological behavioral effects as-received from the manufacturer and after retrieved from patients. MATERIALS AND METHODS: In this, in vitro investigation six sets (maxillary and mandibular) of Vivera® retainers, three as received and three retrieved after four weeks of use by patients of an orthodontic postgraduate clinic, were immersed in the normal saline solution for 14 days following different modes of sterilization. The estrogenicity assays involved two cell lines, namely the estrogen-sensitive MCF-7 and the estrogen-insensitive MDA-MB-231. Following a 6 day incubation with the solutions to be tested, at concentrations varying from 5% to 20% v/v in medium supplemented with 2% fetal calf serum devoid of endogenous estrogens, estrogenicity was assessed by cell counting; p-Estradiol was used as positive control. The statistical analysis of data was performed with two-way analysis of variance (ANOVA) with appliance and concentration as predictors. Differences were further investigated with the Tukey multiple comparison tests at the 0.05 level of significance. RESULTS: No significant MCF-7 proliferation was induced by the three samples compared either to the eluents from as-received retainers or to the negative control. As expected, p-estradiol induced a potent stimulation of MCF-7 cell proliferation, while no effect was observed on MDA-MB-231 cells. CONCLUSION: Under the conditions of this experiment eluents of as-received and retrieved Vivera® retainers did not seem to exhibit xenoestrogenic activity. CLINICAL SIGNIFICANCE: Vivera® retainers can be used as part-time removable oral appliances following the manufacturer's instructions.

Rapid assessment of the physiological status of Streptococcus macedonicus by flow cytometry and fluorescence probes.

Flow cytometry in combination with fluorescence probes was applied to rapidly assess the physiological status of Streptococcus macedonicus ACA-DC 198, a newly described member of the lactic acid bacteria group with technologically important features (e.g. lantibiotic production). A sonication procedure was developed for disaggregating typical streptococci chains in order to optimize cell preparations for single cell analysis. Single stained live and dead populations of S. macedonicus cells were clearly resolved based on membrane potential by bis-oxonol [DiBAC(4)(3)], membrane integrity by Propidium Iodide (PI) and enzymatic activity as well as membrane integrity by Carboxyfluorescein Diacetate (cFDA). Further, estimation of both live and dead cells by a cFDA/PI two-colour flow cytometric assay showed excellent correlation with the dead cells in the samples (dead(FCM)=0.9945 dead(S)-0.806, R(2)=0.9986 and live(FCM)=-0.978 dead(S)+98.895, R(2)=0.9992). Finally, the assay was applied to study the physiology of S. macedonicus after acid stress. Interestingly, in situ assessment of the physiological status of stressed S. macedonicus cells by flow cytometry and single cell sorting revealed the coexistence of three distinct subpopulations according to their fluorescence labelling behaviour and culturability, representing intact/culturable, permeabilized/dead and potentially injured cells with the latter exhibiting both metabolic activity and membrane permeabilization as well as decreased culturability.

Greek centenarians: assessment of functional health status and life-style characteristics.

Centenarians represent an intriguing model for ageing studies, since they demonstrate extreme longevity by definition, and at the same time a proportion of them have aged successfully. Here, we present data from the first nationwide study on Greek centenarians concerning their functional health status and life-style characteristics. We have identified 489 individuals (77% women) born in 1900 or before who were still alive between the years 2000 and 2002. Socio-demographic characteristics, activities of daily living (ADLs), living conditions, dependence on other people, former and current diseases and health disorders, current medication, nutrition and personal habits were recorded for every subject. Interestingly, only 2% of Greek centenarians lived in nursing homes, while the majority lived with their family or relatives. Furthermore, 6% were free from severe health disorders, autonomous (based on simple criteria for ADLs) and also leading an active social life, and hence may be considered as being in optimal condition. This group of centenarians may serve as a valuable source of information on genetic, environmental, and psychosocial determinants of successful ageing.