Search PubMed⌕ Search

Biomedical subjects

P Viallet

Publications and source records attributed to P Viallet.

At least 37 records · Page 2Linked to original sources
PubMed1988

[Use of 1,4 diacetoxy-2,3 dicyanobenzol in microspectrofluorometry for determining the intracellular pH of isolated living cells].

Microspectrofluorometry allows to obtain the fluorescence spectrum of an isolated living cell. When cells are preincubated with 1,4 diacetoxy-2,3 dicyanobenzol the cellular fluorescence spectrum can be resolved in its components i.e. the characteristic fluorescence spectrum of each ionized forms of the probe and the intrinsic cell fluorescence spectrum due to NAD(P)H. This allows the determination of the intracellular pH with good accuracy. Furthermore, comparison between the intensity of the intrinsic cell fluorescence and the probe fluorescence intensity offers us an opportunity to monitor the intracellular amount of the drug.

Animals↗
PubMed1987

Microspectrofluorometric comparison of benzo(a)pyrene and dibenzo(c,h)acridine metabolism in single living 3T3 fibroblasts.

The purpose of this study was to determine if dibenzo(c,h)acridine could be used as a probe for the N-heterocyclic aromatic compound detoxification system. The determination was achieved by cell population studies (histograms) using microspectrofluorimetry on single living cells. The results show a similar metabolic distribution pattern between dibenzo(c,h)acridine and benzo(a)pyrene, whereas important differences appear between 6-aminochrysene and dibenzo(c,h)acridine, respectively amine aromatic and N-heterocyclic aromatic compounds. No differences were observed in the metabolism of benzo(a)pyrene in untreated cells and those treated with constant concentrations of dibenzo(c,h)acridine. However, inhibition of dibenzo(c,h)acridine metabolism was observed in the presence of benzo(a)pyrene, indicating that this compound should be a preferential substrate for a cell detoxification system.

Acridines↗
PubMed1986

[Demonstration of the intracellular accumulation of intermediary fluorescent metabolites of various polycyclic aromatic hydrocarbons by resolution of the fluorescence spectra of isolated living cells].

Using microspectrofluorimetry, we have studied some spectral modifications induced by the accumulation of fluorescent metabolites from some PAH in single living cells (3T3 and RTG2 fibroblasts). Whatever the parent compound under study, no spectral deformation has been detected in the 3T3 cells. On the contrary, the characteristic fluorescence spectra were strongly modified in RTG2 cells when the parent compound was either B(a)P or CPAP. The B(a)P metabolites have been identified as 3-OH-B(a)P and 9-OH-B(a)P.

Animals↗
PubMed1986

[Demonstration of the heterogeneity of the intracellular activity of oxidases by quantitative microspectrofluorimetry: comparison of two cell strains].

A microspectrofluorimeter has been used for kinetic studies of the decrease of polycyclic aromatic hydrocarbons (PAH) fluorescence in single living cells (3T3 and RTG2 fibroblasts). These studies allow the determination of activation rate constants (k) for PAH. The distribution of the cellular populations has been represented as a function of k. The histograms show: an heterogeneity of the cellular population; differences between the metabolic activities of the two strains; modifications of the metabolization depending upon the probe tested.

Animals↗
PubMed1984

Quantitative microspectrofluorimetry study of the "blocking effect" of 6-aminochrysene on benzo[a]pyrene metabolism using single living cells.

By microspectrofluorimetry on single living cells (murine fibroblasts 3T3), we have obtained monoexponential decreases of fluorescence intensity for benzo[a]pyrene (B[a]P) and 6-aminochrysene (6a-chrysene) metabolism. These kinetics are characteristics of B[a]P and 6a-chrysene metabolism and histograms can be drawn from the rate constants. We have studied the influence of 6a-chrysene on B[alpha]P metabolism. Using different methods of incubation, it has been observed that the presence of 6a-chrysene leads to modifications of the histogram profiles during B[a]P metabolism. Polycyclic aromatic hydrocarbons (PAH) are used to induce B[a]P metabolism. Whatever the experimental conditions we never detected such a phenomenon with 6a-chrysene. On the contrary we have observed an inhibition of B[a]P metabolism by 6a-chrysene, which can reach 80% of the aryl hydrocarbon hydroxylase (AHH) activity when 6a-chrysene remains constant in the cells. Compared with the results previously observed "in vitro" which presented 50% mean inhibition) we show that inhibition acts in an all-or-nothing mechanism at the cellular level.

Animals↗
PubMed1981

Slower step of the polycyclic aromatic hydrocarbons metabolism: kinetic data from microspectrofluorometric techniques.

A microspectrofluorometer has been used for kinetic studies of the decrease of benzo(a)pyrene and benzo(k)fluoranthene fluorescence. This decrease is observed for single living cells: L cells and human peripheral blood monocytes, after their incubation which culture medium containing these compounds and washing the petri dish with fresh medium. The entire fluorescence spectra is recorded at given time intervals in order to watch at some eventual spectral modification. The fluorescence decrease is monoexponential and its parameters are computed with a program based on the least squares fit method. Such determination shows no difference between the calculated rate constants of metabolisation for B(a)P and B(k)F and, as long as we consider L cells with a similar morphological shape, only statistical fluctuations of the rate constants of metabolism are observed. As compared, monocytes show faster kinetics of the decrease of the B(a)P intracellular fluorescence due to B(a)P metabolism, and also a more reached dispersion of the values of the rate constant than the one observed for L cells indicating some heterogeneity in the monocyte population of each donor.

Aryl Hydrocarbon Hydroxylases↗
PubMed1979

[Kinetics of the penetration of benzo(a)pyrene and benzo(k)fluoranthene into cells].

Microspectrofluorometric methods have been used to study the kinetics of the increase of fluorescence due to the intake of Benzo(k)Fluoranthène and Benzo(a)Pyrène in single living L cells. A computer program based on the methods of the least square fit has allowed the determination of the kinetic parameters. The results show that pinocytosis cannot be the unique mechanism of intake.

Animals↗
PubMed1979

[Measurement of fluorescence decay of substances absorbed by an isolated living cell: an experimental device and early results].

A microfluorometric system allowing the mesurements of fluorescence decay (i.e. fluorescence lifetime) has been built. It will complete the microspectrofluorometric studies of absorbed compounds-polycyclic aromatic hydrocarbons, metabolites of benzo (a) pyrene-by single living cells and allows a better understanding of the intake and metabolisation of these compounds. The preliminary results with benzo (a) pyrene, dibenzocarbazole, pyrene are shown.

Benzopyrenes↗
PubMed1979

Correlation between macrophage intracellular electrical potentials and malignant melanoma growth in a murine model.

Peritoneal macrophages were collected from mice at varying periods after transplantation of an allogeneic malignant melanoma in the hind limb. The intracellular electrical potentials of these macrophages were measured and a correlation was found to exist between tumor growth measured by size and pathological examination, and the development of large negative intracellular potentials. We propose that this change in intracellular potential is correlated with changes in the immune system and may be triggered by membrane permeability changes possibly in response to calcium ions.

Animals↗
PubMed1978

The effect of atebrine and an acridine analog (BCMA) on the coenzyme fluorescence spectra of cultured melanoma and Ehrlich ascites (EL2) cells.

Coenzyme fluorescence spectra of single living cells are due to free pyridine nucleotides (folded configuration), bound pyridine nucleotides (unfolded configuration) and a third component, possibly a mixture or flavins. Such spectra can be used to recognize possible differences in coenzyme composition between cell lines or changes of metabolic pathways due to chemicals acting at levels below or above cytotoxicity, by high resolution spectrofluorometry. A study of spectra recorded from cultured Ehrlich ascites (EL2), and Harding Passey melanoma cells (HPM-67 and HPM-73 line) grown under comparable conditions, shows that free NAD(P)H predominates in HPM-67 and EL2, while this coenzyme is bound in HPM-73. The free/bound ratio may be profoundly modifed by chemicals, e.g. in the HPM-73 increase of free and decrease of bound NAD(P)H occurred upon treatment with 10(-6) oligomycin. When atebrine at levels (10(-6) M) below cytotoxicity was added, there was a decrease of the free NAD(P)H spectrum possibly through energy transfer from NAD(P)H to atebrine. Consideration of long range energy transfer i.e., excitation of atebrine by fluorescence of NAD(P)H vs. short range transfer of excitation energy from free NAD(P)H to atebrine, favors the latter mechanism. A transient (reversible) increase in atebrine fluorescence is seen following intracellular microinjection of substrate (e.g. glucose-6-P) leading to an increase in free NAD(P)H. At cytotoxic levels of atebrine (e.g 2 x 10(-5) M) an irreversible increase of atebrine fluorescence is seen. The microspectrofluorometric technique appears therefore well suited to study physiological processes at the level of intracellular coenzymes, as well as possible processes of intermolecular energy transfer in the microenvironment.

Acridines↗