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Biomedical subjects

N Pascal

Publications and source records attributed to N Pascal.

14 recordsLinked to original sources
PubMed2001

Design, characterization and preclinical efficacy of a cationic lipid adjuvant for influenza split vaccine.

We prepared a series of cationic lipid vesicles comprising a cationic cholesterol derivative, DC-Chol with or without a neutral phospholipid, DOPC or DOPE. The vesicles were tested for their ability to bind and adjuvant split inactivated influenza vaccines. We found that DC-Chol-containing liposomes are capable to strongly bind influenza vaccine antigens upon simple mixing with the vaccine. The resulting formulations induced robust anti-influenza immune responses both after s.c. and i.n. administration in BALB/c mice while neutral Cholesterol/DOPC liposomes displayed virtually no stable antigen binding and no adjuvant effect. The parenteral adjuvant effect of DC-Chol on trivalent split influenza vaccines was then confirmed in outbred mice and monkeys. Among the most potent formulations tested, a simple mixture of the vaccine with a microfluidized dispersion of DC-Chol in an aqueous buffer is being considered for further development to produce an improved influenza vaccine.

Adjuvants, Immunologic↗
PubMed2000

A convenient semi-quantitative method for the diagnosis of Epstein-Barr virus reactivation.

A semi-quantitative determination of Epstein-Barr virus (EBV) viremia has been devised. Peripheral blood mononuclear cells are recovered by Ficoll gradient and numerated. Five microl aliquots of recovered cell suspension and 5 microl of two standard dilutions (containing 500 and 100 cells, respectively) are subjected to a nested polymerase chain reaction (PCR). This technique has been evaluated over 3 years for the follow-up of 45 patients attending the Bone Marrow Transplantation Unit of the "Centre Hospitalier et Universitaire de Nancy". EBV reactivation was diagnosed in 13 patients (28%). Positivity of PCR for 100 cells was found in 9 patients of whom 6 developed lymphoma or lymphoproliferative disorder. This technique is easy to perform and doesn't necessitate any specific material besides the one necessary for routine genic amplification.

Adolescent↗
PubMed1994

Inhibition of fatty acid desaturation in sycamore cells deprived of iron.

The growth of isolated sycamore cells in a medium devoid of iron induced a marked reduction of the unsaturation level of fatty acids: the proportion of linolenic acid (C18:3) in polar lipids (phospholipids and galactolipids) decreased whereas a parallel increase in the proportions of oleic (C18:1) and linoleic (C18:2) acid was observed. In our experimental conditions, no direct effect of iron deprivation on fatty acid and glycerolipid biosynthesis could be observed. When sycamore cells were incubated in the presence of [14C]acetate, the level of unsaturation in fatty acids was very strongly reduced: no polyunsaturated fatty acids were synthesized in iron-deprived cells: only [14C]palmitic and [14C]oleic acids accumulated in glycerolipids. In contrast, sycamore cells grown in an iron-containing medium in the presence of [14C]acetate were able to synthesize glycerolipids containing 14C-labelled C18:2 and C18:3. We concluded that, in sycamore cells, iron is essential for C18:1-->C18:2-->C18:3 desaturations. In contrast, C18:0-->C18:1 desaturation is much less sensitive to iron deprivation under our experimental conditions.

Acetates↗
PubMed1993

13C nuclear magnetic resonance studies of malate and citrate synthesis and compartmentation in higher plant cells.

The synthesis of malate and citrate by sycamore cells (Acer pseudoplatanus L.) perfused with KH13CO3 was analyzed using 13C NMR. To perform in vivo experiments, cells were compressed in a 25-mm tube and perfused with an arrangement enabling tight control of the circulating nutrient medium. An original method using paramagnetic Mn2+ that induced a complete loss of the vacuolar malate and citrate signals was developed to discriminate between cytoplasmic and vacuolar pools of malate and citrate. Our results indicated the following. (a) The accumulation of appreciable amounts of malate in sycamore cells required rather high (1 mM) concentrations of bicarbonate at all the pH values tested. (b) Malate was equally labeled at C-1 and C-4, suggesting that malate labeled at C-1 was produced by randomization of C-1 and C-4 by mitochondrial fumarase. Indeed, the separation of the intact organelles from the lysed protoplasts indicated that fumarase activity was essentially limited to the mitochondria. Similarly, citrate was equally enriched at C-1 and C-5 + C-6 carboxyls. (c) Malate appeared first in the cytoplasmic compartment; and when a threshold of cytoplasmic malate concentration was attained, malate molecules were expelled into the vacuole, where they accumulated. On the other hand, citrate accumulated steadily in the vacuole. Pulse-chase experiments demonstrated the central role played by the tonoplast in governing the vacuolar influx of citrate and the permanent exchange of malate between the cytoplasm and the vacuole.

Bicarbonates↗
PubMed1990

Comparison of the Kinetic Behavior toward Pyridine Nucleotides of NAD-Linked Dehydrogenases from Plant Mitochondria.

In this article we compare the kinetic behavior toward pyridine nucleotides (NAD(+), NADH) of NAD(+)-malic enzyme, pyruvate dehydrogenase, isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, and glycine decarboxylase extracted from pea (Pisum sativum) leaf and potato (Solanum tuberosum) tuber mitochondria. NADH competitively inhibited all the studied dehydrogenases when NAD(+) was the varied substrate. However, the NAD(+)-linked malic enzyme exhibited the weakest affinity for NAD(+) and the lowest sensitivity for NADH. It is suggested that NAD(+)-linked malic enzyme, when fully activated, is able to raise the matricial NADH level up to the required concentration to fully engage the rotenone-resistant internal NADH-dehydrogenase, whose affinity for NADH is weaker than complex I.

Journal Article↗
PubMed1989

Fc fragment from human IgG induces PGE2 secretion. II. Negative regulation in B cell differentiation.

In humans, in vitro, Fc fragment of IgG at a low concentration induces plasma cell generation. However, Fc fragment at a high concentration induces PGE2 release of monocyte activation capable of inhibiting this differentiation. The levels of PGE2 in the supernatant culture from mononuclear cells from normal donors were examined as a function of culture duration and concentration of Fc, Fab fragments and IgG. Plasma cells containing intracytoplasmic Ig were demonstrated by immunofluorescence with a polyvalent antiserum to human immunoglobulin(s). PGE2 levels, from mononuclear cell cultures, were analyzed by the RIA test. The results indicated that the Fc fragments are able to induce PGE2 secretion. The maximal release of PGE2 occurs after 24 hr of culture; this level is proportionate to the quantity of Fc fragments introduced. The addition of indomethacin in the cell culture stimulated by a high concentration of Fc fragments reestablishes the percentage of plasma cells. These results suggest the regulatory role of Fc fragment by PGE2 secretion in B cell differentiation.

Adult↗
PubMed1978

[Isosorbide dinitrate and bupranolol in the therapy of coronary heart disease (author's transl)].

Sixteen patients with coronary heart disease (CHD) and three healthy volunteers were treated with a combination of a long-acting nitrite and a beta-receptor blocking agent. The drug proved effective in diminishing haemodynamic changes after physical and mental stress, respectively. The implications of these findings are discussed in the light of recent knowledge on CHD pathogenetic mechanisms.

Blood Pressure↗