Showing papers by "University of Nice Sophia Antipolis published in 1993"
TL;DR: It is proposed that the rapid and persistent nuclear transfer of p42mapk and p44mapk during the entire G0-G1 period is crucial for the function of these kinases in mediating the growth response.
Abstract: Mitogen-activated protein kinases (p42mapk and p44mapk) are serine/threonine kinases that are activated rapidly in cells stimulated with various extracellular signals. This activation is mediated via MAP kinase kinase (p45mapkk), a dual specificity kinase which phosphorylates two key regulatory threonine and tyrosine residues of MAP kinases. We reported previously that the persistent phase of MAP kinase activation is essential for mitogenically stimulated cells to pass the "restriction point" of the cell cycle. Here, using specific polyclonal antibodies and transfection of epitope-tagged recombinant MAP kinases we demonstrate that these signaling protein kinases undergo distinct spatio-temporal localization in growth factor-stimulated cells. In G0-arrested hamster fibroblasts the activator p45mapkk and MAP kinases (p42mapk, p44mapk) are mainly cytoplasmic. Subsequent to mitogenic stimulation by serum or alpha-thrombin both MAP kinase isoforms translocate into the nucleus. This translocation is rapid (seen in 15 min), persistent (at least during the entire G1 period up to 6 h), reversible (by removal of the mitogenic stimulus) and apparently 'coupled' to the mitogenic potential; it does not occur in response to nonmitogenic agents such as alpha-thrombin-receptor synthetic peptides and phorbol esters that fail to activate MAP kinases persistently. When p42mapk and p44mapk are expressed stably at high levels, they are found in the nucleus of resting cells; this nuclear localization is also apparent with kinase-deficient mutants (p44mapk T192A or Y194F). In marked contrast the p45mapkk activator remains cytoplasmic even during prolonged growth factor stimulation and even after high expression levels achieved by transfection. We propose that the rapid and persistent nuclear transfer of p42mapk and p44mapk during the entire G0-G1 period is crucial for the function of these kinases in mediating the growth response.
662 citations
Journal Article•
TL;DR: An explanation for the observed difference of physiological effects between amiloride and HOE694 is suggested, and a new Na+/H+ exchanger inhibitor possessing anti-ischemic properties on myocardial cells is identified as a useful tool for studies of Na-H+ exchange.
Abstract: A fibroblast mutant cell line devoid of Na+/H+ exchange was used to stably express cDNAs encoding the NHE1, NHE2, and NHE3 Na+/H+ antiporters. Pharmacological studies using amiloride and two of its 5-N-substituted derivatives, 5-N-dimethyl amiloride and 5-N-(methyl-propyl)amiloride (MPA), demonstrate that the NHE1 isoform is the ubiquitously expressed amiloride-sensitive Na+/H+ antiporter (Ki of 0.08 microM for MPA), whereas the NHE2 and NHE3 isoforms exhibit a lower affinity for these inhibitors (Ki of 0.5 microM and 10 microM, respectively, for MPA) and are therefore likely to be members of the epithelial Na+/H+ exchanger's family. In addition, we have used this system to test a new Na+/H+ exchanger inhibitor possessing anti-ischemic properties on myocardial cells [(3-methylsulphonyl-4-piperidinobenzoyl) guanidine methanesulphonate]. This compound inhibits competitively NHE1 (Ki of 0.16 microM) with a much greater affinity than NHE2 and NHE3 (Ki of 5 microM and 650 microM, respectively) and therefore appears to be much more discriminative between these two classes of antiporter isoforms than the amiloride-related molecules. These results suggest an explanation for the observed difference of physiological effects between amiloride and HOE694, and identify this new inhibitor as a useful tool for studies of Na+/H+ exchange.
249 citations
TL;DR: Seaweed and seagrass populations on the coasts of Monaco and Cap Martin have been significantly reduced or destroyed because of invasion by C. taxifolia.
Abstract: The first report of Caulerpa taxifolia in the Mediterranean is from 1984. The alga was found on the rocky shore at Monaco, below the Oceanographic Museum, where it had been on display in tropical aquaria. Within five years, there was an abundance of C. taxifolia on the shores around the first point of observation. In 1987, C. taxifolia appeared on the French coast, 3 km east of Monaco, at Cap Martin. By late 1991, 30 ha of shore in the vicinity of Monaco was covered with the alga. New points of colonization were in Livorno, Italy, 240 km east of Monaco, and to the west at Agay, Le Lavandou, Hyeres, Toulon, Les Lecques, Saint Cyprien, 50 to 370 km from Monaco. The westernmost point of colonization, noted in September 1992, was 600 km from Monaco, at Majorca (Balearic island, Spain). Most types of substrata, between 0 and 50 m depth, are susceptible to colonization by C. taxifolia. Seaweed and seagrass populations on the coasts of Monaco and Cap Martin have been significantly reduced or destroyed because of invasion by C. taxifolia.
166 citations
141 citations
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TL;DR: In this article, different aspects of the solar interior from both experimental and theoretical points of view are discussed, including photospheric abundances, neutrinos and acoustic mode measurements. But the theoretical approach mainly concerns the classical framework of stellar evolution, nevertheless, particle interpretation of the data and astrophysical solutions invoked in the last 10 years are coherently examined.
136 citations
TL;DR: The clearance from blood circulation of fluorinated liposomes made with perfluoroalkylated phosphatidylcholines was investigated in mice using liposome‐entrapped 5(6)‐carboxyfluorescein and was similar to that of some polyethylene glycol (PEG)‐labelled ‘stealth’liposomes and was dose‐independent in a 3.3–330 body weight dose range.
121 citations
TL;DR: In this article, a 3D simulation of the Coulomb wedge was used to study the formation of transfer zones in the wedge, separating two domains of homogenous behaviour and connecting thrust planes in different domains, and the results of analogue modelling suggest that the development of transfer zone is directly linked to variations in the boundary conditions between two adjacent parts of a thrust wedge.
121 citations
TL;DR: Results support the idea that the columnlike aggregates which have been found in ER fIuids should have a bct structure and an exact analytical derivation of an expression describing the many-body electrostatic forces among spherical polarizable particles in terms of the multipole moments.
Abstract: We present a general method based on a multipole-expansion theory that allows us to calculate efficiently and accurately the electrostatic forces and the dielectric constant of an assembly of spheres. This method is applied to the study of two aspects which play an important role in the behavior of electrorheological (ER) Auids. The first one concerns the calculation of the principal values e~~ and e& of the dielectric tensor of the body-centered-tetragonal (bct) lattice, and the calculation of the induced dipole on the particles in this lattice. These are rigorous calculations on physical properties of interest in the study of ER Auids. These results support the idea that the columnlike aggregates which have been found in ER fIuids should have a bct structure. Although calculations based on the dipolar approach were previously presented, no results are available that confirm this idea rigorously. The second point concerns an exact analytical derivation of an expression describing the many-body electrostatic forces among spherical polarizable particles in terms of the multipole moments. We have compared this force expression, in the case of two-particle interactions, to some results from the literature. It agrees very well with some analytical two-particle expressions for perfectly conducting spheres and also with some recent results concerning the interactions between two polarizable spheres. Furthermore, we present results for three-particle contributions to the electrostatic force and show that these contributions are unexpectedly large. In particular, the rate of divergence of the force between two conducting spheres can be considerably changed by the presence of a third one.
119 citations
TL;DR: This paper presents the implementation of the strategy used in the weather forecasting arpege/ifs project to produce the adjoint code from the code representing the numerical model, and describes the Odyssee system, an open system built as a toolkit, written in a high-level programming language adapted to this purpose.
Abstract: This paper describes the design of Odyssee , a system for fortran programs manipulations and its application to automatic differentiation. The Odyssee system manipulates fortran programs as symbolic objects. It is an open system built as a toolkit, written in a high-level programming language adapted to this purpose. The use of a variational method to perform data assimilation requires the computation of the gradient of a cost function represented by a large-size fortran program. The usual drawback in the reverse automatic differentiation method is the storage requirement. The Odyssee system allows one to implement storage/recomputation strategies in order to fit the needed compromizes. We present the implementation of the strategy used in the weather forecasting arpege/ifs project to produce the adjoint code from the code representing the numerical model. Odyssee produces the same code as the hand-written adjoint code for thearpege/ifs project. DOI: 10.1034/j.1600-0870.1993.00016.x
110 citations
TL;DR: Data suggest that ACS is a highly regulated enzyme with a potentially important control function in lipid metabolism, and it is demonstrated that both nutritional composition and liver proliferation trigger ACS gene expression in liver.
Abstract: Several enzymes of the beta-oxidation pathway have been shown to be induced after stimulation with peroxisomal proliferators, including several hypolipidemic drugs. We investigated the regulation of the long-chain-acyl-CoA synthetase (ACS) gene in the liver. Fenofibrate, a hypolipidemic drug and potent peroxisomal proliferator, induced ACS gene expression in several tissues. In liver, large increases in ACS mRNA levels and ACS activity were observed after fenofibrate administration. Adipose tissue ACS mRNA levels and ACS activity were also stimulated upon fibrate treatment but to a lesser extent in comparison with liver ACS mRNA. Kidney ACS mRNA was only weakly induced, except for the highest dose and the longest treatment period, where a strong induction was observed. In contrast to these tissues, heart ACS mRNA and ACS activity remained almost unchanged after fenofibrate treatment. These effects of fenofibrate could be reproduced by other fibrates such as clofibrate. In addition, it is demonstrated that both nutritional composition and liver proliferation trigger ACS gene expression in liver. Consequently, these data suggest that ACS is a highly regulated enzyme with a potentially important control function in lipid metabolism.
109 citations
TL;DR: It is suggested that HCV could be a frequent triggering factor for sporadic porphyria cutanea tarda.
Abstract: We have studied the prevalence of hepatitis C virus antibodies (anti-HCV) in 13 patients suffering from sporadic porphyria cutanea tarda. The sera were tested by Abbott second-generation enzyme immunoassay; seropositivity was confirmed by Ortho second-generation recombinant immunoblot assay. Ten cases (76.1%) were anti-HCV positive; one patient was also seropositive for HIV. This preliminary study suggests that HCV could be a frequent triggering factor for sporadic porphyria cutanea tarda.
TL;DR: The Ivory Coast-Ghana (ICG) marginal ridge is a prominent feature of the ICG transform margin and includes a fossil ridge partially buried by a thick, undeformed sedimentary cover as discussed by the authors.
TL;DR: An integrated overview of the major advances so made in the chemistry and molecular biology of melanin pigmentation is provided to draw attention to certain peculiarities of the melanization processes of hair with respect to those underlying skin pigmentation.
TL;DR: In this paper, the authors studied the Capillary-gravity solitary waves with damped oscillations and showed that these waves exist for all values of the Froude number smaller than one.
TL;DR: Caulerpenyne, the major metabolite of C. taxifolia, is the most active on sea urchin eggs and may represent an ecological risk for microorganisms and the eggs of multicellular animals living close to this alga.
Abstract: Caulerpa taxifolia (Vahl) C. Agardh (Ulvophyceae, Caulerpales) is an alga of tropical origin that was accidentally introduced into the Mediterranean sea in 1984, where this species can reach an abundance that has never been described in tropical endemic regions. It is known that caulerpacean algae can develop an efficient strategy against grazers consisting of the synthesis of repulsive of toxic secondary metabolites: we report here the first study of the toxicity of purified secondary metabolites and raw extracts fromC. taxifolia from the Mediterranean. Toxicity was evaluated on three models: mice (lethality), mammalian cells in culture (cytotoxicity) and sea urchin eggs (disturbance of cell proliferation). Aqueous extracts are only active on fibroblasts and mice. In the three toxicity models a seasonal variation of toxicity is observed for the crude methanol extract as well as a decrease of this activity whenC. taxifolia from the Mediterranean is kept in aquaria. Pure compounds exhibit different toxicity depending on the assay. 10,11-epoxycaulerpenyne is the most active substance on mice and fibroblasts whereas taxifolial A and D are inactive or only weakly toxic. Among the four tested compounds caulerpenyne, the major metabolite ofC. taxifolia, is the most active on sea urchin eggs. Caulerpenyne may therefore represent an ecological risk for microorganisms and the eggs of multicellular animals living close to this alga. The ecological impact of this toxicity on marine organisms and the interaction of this alga with the herbivorous fauna are discussed.
TL;DR: Results suggest that neurotensin-induced internalization of the 50- and 60-kDa subunits initially present on the cell surface triggers insertion of the 100-k da subunit into the membrane from an intracellular compartment.
TL;DR: The incidence of cardiac toxoplasmosis in this group of immunodepressed subjects from an area with a high prevalence of this parasitic disease justifies regular follow up of such patients by electrocardiography and echocardiography as well as immediate administration of anti-toxoplasma treatment should sudden heart failure occur.
Abstract: OBJECTIVE--To evaluate the prevalence of cardiac toxoplasmosis in a series of 182 necropsies performed between 1987 and 1991 on patients infected with the human immunodeficiency virus (HIV), to correlate this prevalence with the ante mortem diagnosis of cardiac involvement, and to assess the role of such cardiac lesions in the immediate cause of death. PATIENTS AND METHODS--Complete necropsies of 182 HIV-infected patients (48 women, 134 men) were performed consecutively between 1987 and 1991. Risk factors, identified in 174 cases, included drug abuse (111/182), homosexuality (51/182), and blood transfusions (12/182). 16 samples were systematically obtained from each heart for histological study. If trophozoites or lymphocytic myocarditis were seen, immunohistochemical investigations were carried out with polyclonal antibodies for Toxoplasma gondii. An ultrastructural study was performed in four patients with toxoplasma myocarditis. Myocardial lesions were defined by the Dallas classification. Clinical data (and information on electrocardiograms and echocardiograms) were obtained from medical records. RESULTS--Cardiac toxoplasmosis was diagnosed at necropsy in 21 (12%) patients. Cardiac lesions were associated with toxoplasmic encephalitis in 18 patients and were solitary in three patients. Acute diffuse myocarditis was present in 6/21, rare foci of myocarditis were seen in 8/21, and intramyocytic toxoplasmic cysts without any inflammatory reaction or necrosis were seen in 4/21. Anti-toxoplasma immunolabelling showed cardiac toxoplasmosis in three patients with lymphocytic myocarditis. Particles with the ultrastructural characteristics of Toxoplasma gondii trophozoites were seen in four cases. Six patients had presented with cardiac symptoms, confirmed by electrocardiographic and echocardiographic abnormalities during their disease course, and their cardiac lesions were directly responsible for the death. CONCLUSION--Cardiac toxoplasmosis was common in this necropsy series of HIV-infected patients. Cardiac toxoplasmosis had been suspected clinically in four patients. Myocardial lesions were generally asymptomatic and were not discovered until necropsy. Solitary cardiac involvement was not uncommon reflecting parasite reactivation at a myocardial site. The incidence of cardiac toxoplasmosis in this group of immunodepressed subjects from an area with a high prevalence of this parasitic disease justifies regular follow up of such patients by electrocardiography and echocardiography as well as immediate administration of anti-toxoplasma treatment should sudden heart failure occur.
TL;DR: A finite algorithm is constructed which enables one to decide whether the class [f] contains a pseudo-Anosov element, which gives the minimal topological entropy of the isotropy class.
Abstract: Let [f] be an isotopy class of orientation-preserving homeomorphisms of the punctured disc. We construct a finite algorithm which enables one to decide whether the class [f] contains a pseudo-Anosov element. In this case the algorithm defines an invariant train track and the dilatation factor, which gives the minimal topological entropy of the isotropy class
TL;DR: The results suggest that the energy supplied by zooxanthellae photosynthates is necessary for the process of amino acid uptake, and that the Na+-dependent carrier responsible for valine uptake by G. fascicularis is similar to the B0,+ system.
Abstract: The characteristics of valine uptake by isolated microcolonies of Galaxea fascicularis (Linnaeus 1758) were studied under various conditions including light, dark and feeding. The results demonstrated the presence of: (1) a linear component which might represent either a diffusional transport or a low-affinity carrier-mediated transport (apparent carrier affinity >250 μmol·l−1), and (2) a high-affinity active carrier-mediated transport (apparent carrier affinity about 5 μmol·l-1). The latter is mediated by two different systems: (i) a Na+-dependent carrier, stimulated by light and operative in both fed and unfed polyps, and (ii) a Na+-independent carrier, light insensitive and present only in unfed polyps. Competition experiments with other amino acids show that the Na+-dependent carrier is highly specific for neutral amino acids, as indicated by the high inhibition constants of basic and acidic amino acids. Our results suggest that the energy supplied by zooxanthellae photosynthates is necessary for the process of amino acid uptake, and that the Na+-dependent carrier responsible for valine uptake by G. fascicularis is similar to the B0,+ system.
Journal Article•
TL;DR: The large T antigen of polyomavirus (PyLT) efficiently immortalizes rodent fibroblasts, but it is not sufficient to achieve complete oncogenic transformation, and the maintenance of a cellular contingent of germinal origin was suggested by the expression of genes normally transcribed during the premeiotic and early meiotic stages of spermatogenesis.
Abstract: The large T antigen of polyomavirus (PyLT) efficiently immortalizes rodent fibroblasts, but, unlike SV40 T antigen, it is not sufficient to achieve complete oncogenic transformation We analysed a series of transgenic mouse families that express the PyLT protein under control of the viral enhancer-promoter region In all of them, the transgene was expressed in the seminiferous epithelium of the testis (Sertoli and germ cells), with no pathological consequences during most of the animals' lives However, every old male developed large bilateral tumours of the testes, generated by the proliferation of Sertoli cell derivatives Cell lines could be readily established both from the tumours and from the still apparently normal testis before the onset of tumoral growth They retained in vitro morphological and ultrastructural features characteristic of Sertoli cells But, in addition to this major Sertoli component, the maintenance of a cellular contingent of germinal origin was suggested by the expression of genes that are normally transcribed during the premeiotic and early meiotic stages of spermatogenesis (LDH-X, Hox14 and c-kit) The two cell types remained tightly associated, even at late passages in culture, and could not be separated by conventional cloning procedures This association in culture of the two cell types whose interaction is critical for spermatogenesis may provide a useful tool for its molecular analysis
TL;DR: In this paper, the gas phase basicity scale for organic compounds up to proton affinity, PA = 1050 kJ mol−1, was reexamined in its upper part.
Abstract: By building a relative basicity ladder, the current basicity scale (Lias et al., J. Phys. Chem. Ref. Data, 17 Suppl. No. 1 (1988)) has been reexamined in its upper part, and extended for organic compounds (amenable to proton transfer measurements) up to proton affinity, PA = 1050 kJ mol−1. Structural effects involved in superbasicities are briefly discussed and routes to further extension of the gas-phase basicity scale for organic compounds are proposed.
TL;DR: The way the French perceived the Californian myth in the sixties led them to develop the fun movement around the key concept of the "whiz", that is, speed, fluidity, entertainment, freedom linked to the imaginary notion of "kick" which stands for new sensations, a sense of harmony, of risk, a taste for the extreme as mentioned in this paper.
Abstract: The way the French perceived the Californian myth in the sixties led them to develop the fun movement around the key concept of the "whiz", that is, speed, fluidity, entertainment, freedom linked to the imaginary notion of "kick" which stands for new sensations, a sense of harmony, of risk, a taste for the extreme Whether it be snow or sea surfing, fun board, skate board, paragliding, parascending, bungee jumping etc, whether it be on snow, water, concrete or in the air, fun space is a "sport" — by which is meant a space situated mid-way between myth and reality - where the whiz stars embody contradictory values
TL;DR: This immunophenotyping study suggests that SH could affect the antigen‐presenting activity of Factor XIIIa cells, i.e., the skin dermal dendrocyte.
Abstract: A case study of sinus histiocytosis of Rosai-Dorfman (SH) clinically limited to the skin is presented with immunohistochemical study of the infiltrate, in both paraffin and cryostal sections. Factor XIIIa, a dendrocyte marker, was demonstrated in the cytoplasm of histiocytes. This feature had not been previously reported in this disease. In addition, the cells expressed S100 protein, CD4, CD la, GD68, and GD11c. This immunophenotyping study suggests that SH could affect the antigen-presenting activity of Factor XIIIa cells, i.e., the skin dermal dendrocyte.
TL;DR: The results suggest that the melanin-concentrating hormone neuronal system plays an important role in integration processes relative to nocturnal regulation of water homeostasis and drinking behavior and osmotic stimulations lead to a selective and conspicuous inhibition of melan in-concence hormone gene activity in the whole hypothalamus of rat.
TL;DR: In this article, the basic ingredients for photon correlation experiments are described and the measured signal simply related to the size of the suspended liposomes undergoing a Brownian motion, and various data analysis procedures are explained.
TL;DR: 23 cases of extracerebral toxoplasmosis diagnosed between 1987 and 1991 in an autopsy series of 170 patients infected with the human immunodeficiency virus (HIV), with clinical and paraclinical findings suggested cardiac involvement in 4 patients.
Abstract: Summary Although Toxoplasma gondii frequently causes lesions of the central nervous system in AIDS, the exact incidence of extracerebral toxoplasmosis in these immunodepressed patients remains difficult to determine. Isolation of the parasite outside the central nervous system is rarely performed ante mortem, and most diagnoses of extracerebral toxoplasmosis are made post mortem. This article describes 23 cases of extracerebral toxoplasmosis diagnosed between 1987 and 1991 in an autopsy series of 170 patients infected with the human immunodeficiency virus (HIV). Ante mortem diagnosis of extracerebral involvement was affirmed in 4 of these 23 patients by identification of trophozoites in bronchoalveolar lavage fluid (2 cases), a surgical pulmonary biopsy specimen, and a bladder biopsy. Clinical and paraclinical findings suggested cardiac involvement in 4 other patients. Post mortem examination demonstrated disseminated toxoplasmosis in 18 cases and extracerebral monovisceral involvement in 5 cases. Extracerebral toxoplasmosis was directly responsible for the death of 6 patients. The most frequent extracerebral sites of Toxoplasma gondii involvement were the heart (21/23 cases; 91 %), the lungs (14/23 cases; 61 %) and the pancreas (6/23 cases; 26 %). The tissular consequences of toxoplasmic involvement varied considerably, from formation of pseudocysts or cysts without any surrounding inflammatory reaction to necrotic lesions rich in neutrophilic polynuclear cells containing numerous free parasites. Immunoperoxidase study using antitoxoplasmic antibodies contributed to the diagnosis of 8 extracerebral localizations. Electron microscopy examination of a surgical lung biopsy and myocardial specimens (2 cases) demonstrated the ultrastructural characteristics of Toxoplasma gondii trophozoites. The particularly elevated incidence of extra cerebral toxoplasmosis in this autopsy series (14 %) can be explained by the high prevalence of toxoplasmosis in France, the prolonged survival of HIV-infected patients and the high number of post mortem samples examined.
TL;DR: T3 appears to be a hormone capable of modulating both proliferation and differentiation of preadipocytes, and ceased to be necessary provided the culture medium was supplemented with high concentrations of inducers of differentiation, such as 8-bromo-cAMP or carbaprostacyclin.
TL;DR: In this paper, the primary and subsequent gas phase reactions between methanol and the isovalent rare earth metal ions Sc +, Y + and Lu + have been investigated using a Fourier transform ion cyclotron resonance mass spectrometer.
01 Jan 1993
TL;DR: In this paper, the Betti lattice in the algebraic fundamental group for the projective line minus three points is shown to be equivalent to the one in this paper, and a generalization for smooth, algebraic varieties over an arbitrary field of characteristic zero is proposed.
Abstract: Let X be an arc-connected and locally arc-connected topological space and let I be the unit interval. Applying the connected component functor to each fibre of the fibration of the total space map(I, X) over X × X, P(w) = (w(0), w(1)), we get a local system of sets (Poincare groupoid) over X × X. This construction does not have a straightforward generalization to algebraic varieties over any field. Using cosimplicial objects, we propose a generalization for smooth, algebraic varieties over an arbitrary field of characteristic zero. This leads to a definition of an algebraic fundamental group of De Rham type. We partly calculate the Betti lattice in the algebraic fundamental group for the projective line minus three points.