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Biomedical subjects

P Viallet

Publications and source records attributed to P Viallet.

At least 55 records · Page 3Linked to original sources
PubMed1978

[Kinetics of decrease and apparent transformation of fluorescence spectra of benzo(a)pyrene absorbed by living cells: case of lymphocytes and macrophages].

A home made microspectrofluorimeter is used in order to follow the decrease of fluorescence intensity of Benzo(a)Pyrene after its absorption by single living cells. The kinetics look to be a first order one; fluorescent metabolite can be detected when peritoneal macrophages of Mice are used but not with human periferic lymphocytes pretreated with mitogens.

Absorption↗
PubMed1978

[Rapid recording of the fluorescence spectrum emitted by an isolated living cell].

In order to use the selectivity of fluorescence emission for biomedical purposes, a microspectrofluorimeter has been built around an inverted microscope. The excitation is supplied by a 450 W Xenon lamp coupled with a monochromator allowing excitation from 230 to 600 nm. The fluorescence is analysed by a Grism (association prism-grating) and the spectrum focused on the 500 channels of the target of an Optical Multichannel Analyser. Related to good resolution and dispersion (0.44 nm/channel), improvement of signal to noise ratio (dark current suppression, and accumulation of spectra), this microspectrofluorimeter with high sensitivity is well adapted to the study of biological mechanism in single living cells (macrophages, monocytes, lumphocytes).

Cells↗
PubMed1977

[The use of arteriography in the pharmacological study of a vasodilator substance].

The administration of a vasodilator substance is followed by the development of a higher contrast gradient in a given film in comparison with a reference X-ray carried out in the same subject under comparable technical conditions. Comparative densitometric measurement of the contrast gradient in the two successive arteriographic series, one with and one without the injection, arterial or venous, of a vasodilator substance (Couramine-Rutine) represents a valuable method for the study in man of the action of the substance in a visceral territory. The present study was limited to the kedney (79 cases), ans the territory of the superior mesenteric (46 cases). The absence of any densitometric difference between the two renal series at too low doses of vasodilator substance leads to the supposition of the possibility of a threshold dose of pharmacological activity.

Absorptiometry, Photon↗
PubMed1976

Rapid microspectrofluorometric studies in EL2 cells following intracellular accumulation of dibenzocarbazoles.

Microspectrofluorometric observations were carried out in EL2 ascites cancer cells and dibenzo(a,e)fluoranthene (diB(a,e)F)-grown EL2 cells, following treatment (5 min) with three dibenzocarbazoles (1,2,7,8; 1,2,5,6 and 3,4,5,6). After microinjection of glucose-6-P leading to reduction of NAD(P), a sequence of difference spectra (after substrate minus before) is recorded. In dibenzocarbazole-untreated cells, maximum (NAD(P) reduction (emission maximum at 465-475 nm) is attained within 5 s, followed by a gradual return to initial fluorescence within 20 to 200 s (faster in the diB(a,e)F-grown). In dibenzocarbazole-treated cells there is a rather regular increase in the intensity of the difference spectrum up to approximately 300-500 s. Initially the increase is more predominant in the region around 460-470 nm, but it gains later prominence in the shorter wavelength region (420-430 nm) characteristic of the hydrocarbon (higher and steadier increase in the 3,4,5,6, dibenzocarbazole-treated diB(a,e)F-grown). Subsequently there is a gradual decrease of fluorescence which may or may or not return to initial level. The observed increase spectra require evaluation in terms of possible components (e.g. a mixture of NAD(P)H and hydrocarbon, binding changes, succession of fluorescent metabolites).

Carbazoles↗
PubMed1976

A preliminary microspectrofluorometric study of NAD(P) reduction in dibenzo(a, e) fluoranthene-treated single living cells.

The fluorescence increase, due to NAD(P) reduction, following microelectrophoretic injection of glucose 6-P (G6P) into EL2 and NCTC 8739 single living cells treated with diBenzo(ae) Fluoranthene (diB(ae)F) and non-treated, has been studied with a rapid microspectrofluorometer. This study shows the enhanced capacity of treated cells to utilize larger doses (6-10 times more) of G6P than control cells. The time course of the return to the initial fluorescence level is essentially related to the magnitude of the injection dose. There are alterations (e.g. red & blue shifts) in the fluorescence spectrum of diB(ae)F-treated cells before injection and in the increase spectrum after injection of G6P, as compared to the same spectra in the diB(ae)F-untreated cells. This is discussed in reference to the metabolization of diB(ae)F as an alternative pathway for the reoxidation of NAD(P)H.

Animals↗
PubMed1976

[Capacity of cells in culture to a accumulate polycyclic aromatic hydrocarbons at microspectrofluoremetric detectable levels. Preliminary results].

In the course of more general microspectrofluorometric studies on intracellular metabolic control mechanisms, the behaviour of living cells was investigated in culture media containing traces of Benzo(a)Pryene (BP) difficultly recordable by spectrofluorimetry. A rapid transfer of BP to the intracellular phase with accumulation was observed. In this manner the recording of the hydrocarbon fluorescence emission spectrum from one single cell became very easy. This fact has led to the investigation of the experimental conditions required for a quantitative detection of trace amounts of aromatic hydrocarbons, and the results presented here are the initial finding of such analysis. In a first part, the requirement for a recording of the complete fluorescence emission spectrum will be emphasized as a condition for a quantitative results. The second part of the presentation is devoted to observations effectively made on fluoresence emission spectra recorded from cells grown in the presence of traces of BP. Due to the aim pursued it is evident that the cells selected for this type of studies should exhibit a relatively slow metabolization of the hydrocarbon. Two significant facts emerge: (a) in most cases the fluorescence spectrum recorded from BP-medium grown cells is not identical to that of BP in solution (less defined structure, displaced maxima, and modified relative intensities of maxima). The spectrum observed in the BP medium grown cells is apparently the result of two spectra, one corresponding to a free BP fraction, the other to a BP fraction interacting with cellular constitutents. (b) When the cells were maintained for periods up to one to three months in presence of low amounts of BP, it was noticed that the BP fractions "interacting" seemed relatively more significant than in cells non "adapted"to BP. Both results are evidently subject to biological intrpretations outside the scope of this communication. However, they permit to draw the attention on the fact, that the quantitative determination of the hydrocarbon in the living cell can be achieved only after definition of a sufficiently precise experimental protocol.

Benzopyrenes↗
PubMed1975

The UV fading of hydrocarbon fluorescence and its prevention for observations in single living cells.

Excitation intensities used for standard microspectrofluorometric observations of natural cell fluorescence, i.e. NAD(P)H, lead to fading of hydrocarbon (polycyclic aromatic, heterocyclic) fluorescence in EL2 cells incubated with such compounds. The disappearance of hydrocarbon fluorescence under excitation at 366 nm seems to be an exponential function of time. The fading prevents studies on hydrocarbon metabolization in correlation with intracellular microelectrophoretic injection of substrate, e.g. glucose-6-P. A return to 8-10 times less intense excitation conditions used in an earlier prototype microspectrofluorometer, has allowed the observation of sequential changes in the difference spectra (after glucose-6-P minus before) of hydrocarbon-treated cells (e.g. benzo(a)pyrene, dibenzocarbazols). The possible relative contributions of NAD(P)H and hydrocarbon metabolites (or alterations) to such sequential spectra are still under consideration, but the main obstacle to their observation, fading, is removed by less intense excitation.

Carcinogens↗
PubMed1958

[Radiology].

Explore the source record for details and available documents.

Humans↗
PubMedDate not supplied

Multiwavelength videomicrofluorometric study of cytotoxic properties of a marine peptide, didemnin B, using adriamycin as reference compound.

Didemnin B (DB), a marine natural product, has very encouraging biological activity in vitro (Antineoplastic, immunosuppressive, antiviral). To learn more about its intracellular effects and targets, videomicrofluorometry on single living cells and a protocol of multiple labeling: Hoechst 342 for nuclear DNA, Rhodamine 123 for mitochondria and Nile Red for plasma membrane, have been used. DB behaves differently from Adriamycin, inducing at its IC50 dose of (20 nM) an accumulation of the CEM-WT lymphoblasts in the S phase of the cell cycle while we observed a 50% decrease of the mitochondrial labeling by R123, showing a decrease of the mitochondrial energetic state. Cytostatic dose of DB (250 nM) confirms these observations. However the treatment with a dose reported as apoptotic (1000 nM) induces a much faster effect (corresponding to that of 72 hours at the IC50 dose), 24 hours incubation induced a drastic decrease of nuclear DNA content as well as of the mitochondria energetic state. The evolution of NAD(P)H cellular content exhibited an increase that seems to indicate that the decrease of mitochondrial energetic state was dependent on inhibition of the mitochondrial activity due to an effect of DB at the mitochondrial level, either direct or mediated. Furthermore, the decrease of mitochondrial labeling appears as a very early event in the mechanisms leading to apoptosis.

Apoptosis↗
PubMedDate not supplied

Multiwavelength videomicrofluorometric study of cytotoxic effects of a marine peptide, didemnin B, on normal and MDR resistant CCRF-CEM cell lines.

The development of multidrug resistance (MDR) in heterogeneous cell sensitive and resistant populations to a variety of clinically important cytotoxic drugs poses a major obstacle to cancer chemotherapy. Didemnin B, a marine cyclic depsipeptide, displays interesting biological properties: antiviral activity, inhibition of DNA, RNA and protein synthesis, initiation of apoptosis and ability to block the cell cycle. As very little is known about its mode of action, we studied the effect of increasing doses of Didemnin B on sensitive and resistant human leukemic lymphoblast cell lines. The fluorescence of living cells simultaneously stained with Hoechst 33,342, Rhodamine 123 and Nile Red, were analyzed in a multiparametric approach involving multiwavelength microfluorometry. High concentrations of Didemnin B induced, in the sensitive cell line, a very early decrease in the energetic state of the mitochondria that occurs before a significant decrease of nuclear DNA content, observed simultaneously on sensitive and resistant cells, that could be related to an apoptosis process. Furthermore low Didemnin doses (50 nM) affected CEM-WT and CEM VLB differently, while higher doses (200 nM-250 nM and over) affected the two cell lines in the same way. This indicated that, at these doses, the membranar Pgp has no effect on the mode of action of Didemnin, suggesting that Didemnin does not need to be internalized to be active.

Antineoplastic Agents↗