Biomedical subjects

P Leprat

Publications and source records attributed to P Leprat.

4 recordsLinked to original sources

PubMed2004

Involvement of reactive oxygen species in the bactericidal activity of activated carbon fibre supporting silver; Bactericidal activity of ACF(Ag) mediated by ROS.

An activated carbon fibre supporting silver (ACF(Ag)) was tested for its antibacterial capacity against Escherichia coli (E. coli). Water that has passed through ACF(Ag) demonstrated strong bactericidal ability. This activity decreased over the time suggesting that generated bactericidal species were short lifespan. Since formation of reactive oxygen species (ROS) might be catalysed by silver impregnated and/or ACF itself, implication of ROS and silver was evaluated by the use of ROS scavengers and a silver ions neutralizing agent. The role of ROS in the E. coli mortality was confirmed by the use of a molecular approach which revealed a strong expression of oxidative stress genes.

Escherichia coli↗

PubMed1990

A new method for testing cell ageing using two mitochondria specific fluorescent probes.

Cell culture techniques have considerably improved our understanding of the numerous changes related to aging. For instance, murine lymphocytes obtained from animals older than 6 months progressively lose their, in vitro, proliferative capacity. Numerous studies have shown that this loss is due to changes in the mitochondrial compartment such as reduction in the transmembrane potential and/or membrane mass. Using two mitochondria specific probes with a potential-dependent (Rhodamine 123) or independent (Nonyl Acridine Orange) uptake, we found that the decline in the respiratory activity in the mouse occurred approximately 6 months prior to the decrease in mitochondrial membrane mass. The analysis of the Rh 123/NAO fluorescence ratio measured in splenocytes obtained from mice aged more than 6 months, showed that there was a linear loss of respiratory efficiency per unit of mitochondrial membrane mass. Moreover, cells with a ratio of less than 0.85 were incapable of proliferating and remained quiescent. The time separating the infection points of the two dye uptake curves might provide informations about the regulation and coordination of nuclear and/or mitochondrial genomes. Moreover, the ratio between the two fluorescent probes, in particular during the linear phase, may also have a predictive value.

Acridine Orange↗

PubMed1990

Use of nonyl acridine orange and rhodamine 123 to follow biosynthesis and functional assembly of mitochondrial membrane during L1210 cell cycle.

Specific mitochondrial incorporation of 10 N-nonyl acridine orange (NAO) is demonstrated by subcellular fractionation of rat hepatocytes. Moreover, comparative studies with NAO and rhodamine 123 (Rh 123) prove that acridine orange-derivative uptake is independent of transmembrane mitochondrial potential, a property allowing its utilization for the assessment of mitochondrial membrane mass modifications under various physiological states. Using NAO and Rh 123, we have respectively followed the biosynthesis of mitochondrial membrane and its assembly under a functional state during the L1210 cell cycle. Their evolution occurs in two stages according to a well-defined sequential order. Mitochondrial biogenesis, as revealed by NAO incorporation, occurs essentially in the G1 phase (probably mitochondrion enlargement) but also starts in late S phase (probably mitochondrion division). The increased amount of functional mitochondrial membrane, monitored by Rh 123 uptake, is emphasized in late G1 (prerequisite to DNA synthesis) and during G2M phases (prerequisite to mitosis). This alternative succession of phases displays the existence of a time-lag between the biosynthesis of mitochondrial membrane and its functional organization. Such an analysis confirms the potential of the NAO probe to evaluate mitochondrial membrane mass changes in various biological fields.

Acridine Orange↗

PubMed1988

In situ flow cytometric analysis of nonyl acridine orange-stained mitochondria from splenocytes.

Due to its spectral characteristics, the fluorochrome nonyl acridine orange (NAO) (lambda abs:489 nm, lambda em:525 nm), which is spontaneously incorporated by mitochondria with a high relative specificity, provides a new probe for the in situ study of these organelles by flow cytometry. In 15 min at 20 degrees C, the dye at 4.75 X 10(-6) M saturates the mitochondrial binding sites present in 1.5 X 10(6) cells. Unlike Rh 123, the fixation of the probe is not affected by the action of uncouplers and ionophores. Unlike acridine orange, its binding is not sensitive to nucleases. By studying the mitochondrial incorporation of the fluorochrome during the cell cycle of murine splenocytes, it was possible to show that the biogenesis of NAO-stained mitochondrial constituents mainly occurs during the G1 phase.

Acridine Orange↗