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Biomedical subjects

C Escoffier

Publications and source records attributed to C Escoffier.

10 recordsLinked to original sources
PubMed2000

Interaction of CD46 with measles virus: accessory role of CD46 short consensus repeat IV.

To define further the accessory role(s) of the CD46 (membrane cofactor protein) short consensus repeat (SCR) III and IV domains in the interaction of CD46 with measles virus (MV), chimeric proteins were generated by substituting domains from the structurally related protein decay accelerating factor (DAF, CD55): x3DAF (exchange of CD46 SCR III) and x4DAF (exchange of SCR IV). Transfected CHO cell lines that stably expressed these chimeric proteins were compared for MV binding and infection. Compared with wild-type CD46 (I-II-III-IV), a significant decrease in MV binding was observed with x4DAF. Despite this limited binding, these cells were still capable of supporting virus entry. In a quantitative fusion assay, no significant differences in fusion were observed as a result of the exchange of either CD46 SCR III or IV. However, the down-regulation of cell surface CD46 typically observed following MV infection was abolished with x4DAF, as was the redistribution of CD46 on the cell surface. Thus, CD46 SCR IV appears to be required for optimal virus binding and receptor down-regulation, although importantly, in spite of these functional limitations, x4DAF can still be used for MV entry.

Animals↗
PubMed1999

Effects of fibronectin on hydroxyapatite formation.

There is increasing evidence that noncollagenous matrix proteins initiate bone mineralization in vivo. Fibronectin, which is present during the early phases of mineralization, may contribute to this process in bone tissues. In this context, the mineralization potential of fibronectin was tested in an agarose gel precipitation system and a metastable calcium phosphate solution. The protein inhibited the precipitation of calcium phosphate crystals in solution but had no apparent effect in gel. Conversely, fibronectin stimulated crystal formation when apatite powder was used to seed crystal growth in gel. Although these results in vitro do not clearly indicate that fibronectin is involved in the mineralization process, they are consistent with in vivo events. Free fibronectin (e.g. in biological fluids) could inhibit crystal growth but might also activate the mineralization process when absorbed on apatite powder in a bone environment and areas of ectopic mineralization.

Animals↗
PubMed1999

Nonstructural C protein is required for efficient measles virus replication in human peripheral blood cells.

The P gene of measles virus (MV) encodes the phosphoprotein, a component of the virus ribonucleoprotein complex, and two nonstructural proteins, C and V, with unknown functions. Growth of recombinant MV, defective in C or V expression, was explored in human peripheral blood mononuclear cells (PBMC). The production of infectious recombinant MV V- was comparable to that of parental MV tag in simian Vero fibroblasts and in PBMC. In contrast, MV C- progeny was strongly reduced in PBMC but not in Vero cells. Consistently, the expression of both hemagglutinin and fusion proteins, as well as that of nucleoprotein mRNA, was lower in MV C--infected PBMC. Thus, efficient replication of MV in natural host cells requires the expression of the nonstructural C protein. The immunosuppression that accompanies MV infection is associated with a decrease in the in vitro lymphoproliferative response to mitogens. MV C- was as potent as MV tag or MV V- in inhibiting the phytohemagglutinin-induced proliferation of PBMC, indicating that neither the C protein nor the V protein is directly involved in this effect.

Animals↗
PubMed1999

Infection of chicken embryonic fibroblasts by measles virus: adaptation at the virus entry level.

Measles virus (MV) has a tropism restricted to humans and primates and uses the human CD46 molecule as a cellular receptor. MV has been adapted to grow in chicken embryonic fibroblasts (CEF) and gave rise to an attenuated live vaccine. Hallé and Schwarz MV strains were compared in their ability to infect both simian Vero cells and CEF. Whereas both strains infected Vero cells, only the CEF-adapted Schwarz strain was able to efficiently infect CEF. Since the expression of the human MV receptor CD46 rendered the chicken embryonic cell line TCF more permissive to the infection by the Hallé MV strain, the MV entry into CEF appeared to be a limiting step in the absence of prior MV adaptation. CEF lacked reactivity with anti-CD46 antibodies but were found to express another protein allowing MV binding as an alternative receptor to CD46.

Adaptation, Physiological↗
PubMed1997

CD46 short consensus repeats III and IV enhance measles virus binding but impair soluble hemagglutinin binding.

The binding of a recombinant soluble form of the measles virus (MV) hemagglutinin (sH) to cells expressing hybrid CD46/CD4 proteins was compared to that of purified virus. For binding of both ligands, both CD46 external short consensus repeats I and II (SCR I and II) in the natural order were essential. The addition of SCR III and IV enhanced virus binding but inhibited sH binding. Accordingly, this lowered the ability of sH to compete with MV binding. Antihemagglutinin monoclonal antibodies selectively inhibited the binding of either sH or MV. Thus, sH and MV share a common binding site in SCR I and II but differ in their apparent avidity to CD46 under the influence of SCR III and IV.

Animals↗
PubMed1990

Reversal effects of topical retinoic acid on the skin of kidney transplant recipients under systemic corticotherapy.

The systemic long-term corticosteroid treatment administered to kidney graft recipients (KGR) within the framework of the required immunosuppressive therapy induces an atrophy of the skin, from the sixth month onwards. We studied the effect of topical all-trans retinoic acid (0.05%; Galderma Labs.) applied to the forearms of 27 KGR (14 men, 13 women) over a 6-month period. Twenty-four subjects completed the trial. The following results were obtained in the treated forearm versus the untreated forearm (excipient alone): clinically, an increase in skin thickness; by noninvasive techniques, an increase in skin thickness, skin elasticity, skin conductance, and TEWL, and a reduction in the size of the corneocytes. No change in stratum corneum lipid content was observed. A sex-related difference was noted in the response to treatment under our experimental conditions, the female patients responding better. A punch biopsy (4 mm) was performed on both forearms of four patients after the 6-month period. Histologic and ultrastructural examination revealed epidermal and dermal changes evoking increased cellular metabolism in the retinoic acid-treated forearms.

Administration, Topical↗
PubMed1989

Assessment of aging of the human skin by in vivo ultrasonic imaging.

The ultrasonic imaging technique that we have developed provides cross-sectional images of human skin in vivo with a resolution of about 80 microns axially (i.e., deep into the skin) and 250 microns lateral (parallel to the surface). In order to study aging skin, we obtained ultrasonic images from the mid-forearm (volar and dorsal sides) of 142 women. Ultrasonically, on the images, the dermis appears composed of two bands: a dark superficial one where the ultrasonic waves are propagated in a relatively homogeneous or non-echogenic medium, and a deeper one, which is lighter in color, suggesting a heterogeneous medium. Our results show that skin is thicker on the dorsal than on the volar forearm. In contrast to previously published results, skin thickness remains constant until the seventh decade of life, diminishing thereafter. The relative thickness of the two bands show marked variations with age: a progressive thickening of the dark band, from zero in infants to approximately 75% of total skin thickness in aged subjects, while the light band shows the inverse trend. Comparing the amplitude of the bands on the volar and dorsal forearm, the relative thickness of the dark band is larger on the dorsal (exposed) side and increases with age. These findings and the analysis of variously stained biopsies taken in some of our patients lead us to assign this dark band to a zone in the upper dermis where the collagen network is delicate, dense, and well organized. This is supported by some data in the literature. The thickness of this subepidermal non-echo-genic band appears to be a far more sensitive marker of skin aging at the dermal level than is the measurement of skin thickness.

Aging↗
PubMed1989

Age-related mechanical properties of human skin: an in vivo study.

We have investigated in vivo how various viscoelastic parameters that describe the mechanical properties of the human skin may vary with age. Accordingly, we have used a mechanical device that records the torsional extensibility of the skin. When submitted to a low torque, the time-response curve of the skin affords the determination of the immediate extensibility (UE), the immediate recovery (UR), the viscoelastic part of the deformation (UV), the elastic recovery (UR/UE), and the creep relaxation time (tau). Because the skin thickness varies with age and primarily governs the mechanical properties, it was measured through an ultrasound technique at the same sites (forearm) where the torque was applied. The results show that the skin maintains its thickness and extensibility up to the seventh decade as opposed to its elasticity or recovery capacities, which decrease from an early age. The viscous part of the deformation is constant through life, whereas the creep relaxation time decreases linearily with age. Except for skin thickness, no differences in these parameters between men and women were detected. The significance of these results are discussed in terms of structure alterations. The determination of the elastic recovery (UR/UE) appears to be a parameter of choice for illustrating skin aging.

Adolescent↗
PubMedDate not supplied

[Quality of life of children: importance of its evaluation. Comparison of children in good health with those at risk (psychological, social, somatic)].

A multicentric study was performed in France and Spain: 490 children were evaluated with a previously validated questionnaire including open-ended questions and structured response format questions. Children are either in good health or suffering from somatic diseases, psychological problems or social difficulties; 38% of the children are Spanish, 62% are French; the questionnaire validation was checked again, and confirmed. Children are happy about their leisure, and unhappy when separated from their families. Among the factors affecting the answers to the structured format questions the most important are the social difficulties and to a lesser extent the psychological problems. Somatic diseases impair the child's quality of life in Spain. Children differ according to the country where they live. Among children in good health, Spanish children report a better quality of life than French children. Open-ended answers were only studied in France. They were very different when children with social difficulties or psychological problems filled out the questionnaire and were compared to children in good health or with somatic diseases. Both children with psychological and social difficulties mention more often the relationship domain. Children with social problems never mention their activities as a source of happiness.

Child↗