Search PubMed⌕ Search

Biomedical subjects

L Dubertret

Publications and source records attributed to L Dubertret.

At least 253 records · Page 14Linked to original sources
PubMed1990

[New valvular homografts. Prospects and limits of their viability. Report of 42 implantations].

The regain of interest in aortic homograft bioprostheses is related to the prospects of improved viability resulting from explanation from organ donors, preservation in rich tissue culture media, together with the progress made in techniques of cryopreservation. Viability studies examining morphology of electron microscopy and tests of tissue culture confirm this notion of longer viability. These properties raise hopes of satisfactory long-term results while acknowledging outstanding antigenic problems which require strict A-B-O system compatibility. The results of a preliminary series of 42 valve homografts implanted at Henri Mondor Hospital over the last 5 years are reported. Twenty-one bioprostheses were implanted on the right side in congenital heart disease with good results in every case. Twenty-one were implanted in the aortic position in children and show no signs of degeneration as yet. One poor result was related to a technical error in calibration. The rebirth of this technique raises certain hopes, especially in aortic valve replacement.

Adolescent↗
PubMed1990

[Viability of new valvular homografts. An evaluation at the Henri Mondor Hospital].

The renewed interest in valvular homograft is due to the new concept of their viability. This viability requires procurement from organ donors and preparation in rich tissue culture medium immediately prior to cryopreservation. This viability, confirmed by morphological tests especially electron microscopy, and by cell culture tests is the basis for satisfactory long-term results. Antigenic aspects justify rigorous respect of A-B-O compatibility. A preliminary clinical series of 35 valvular homografts (16 on the right side and 19 in the aortic position), implanted especially in children over the last five years at the Henri Mondor Hospital, is reported here, No tissue failures have been reported to date.

Aortic Valve↗
PubMed1990

[Stimulation of epidermal growth in equivalent skin by tissue inhibitor of metalloproteases].

Tissue inhibitor of metalloproteases (TIMP) is a major regulator of extracellular matrix synthesis and degradation. Moreover elevated tissue inhibitor of metalloproteases levels are found in the blister fluid of many diseases, suggesting that tissue inhibitor of metalloproteases plays a role in epidermal and dermal wound healing. The aim of this work was to study the effects of human recombinant tissue inhibitor of metalloproteases in a skin equivalent model used to evaluate the effects of drugs on epidermal and dermal components. Planimetry, DNA assays, and histologic studies showed that tissue inhibitor of metalloproteases enhanced the growth of normal human keratinocytes on dermal equivalent. Thus, the extracellular matrix regulator tissue inhibitor of metalloproteases also stimulates the growth of keratinocytes. Identity of the gene encoding tissue inhibitor of metalloproteases and Erythroid Potentiating Activity (EPA) has been reported. The effects of tissue inhibitor of metalloproteases on keratinocytes described herein are reminiscent of the stimulating effect of erythroid potentiating activity on the growth of erythroid precursors.

DNA↗
PubMed1989

[Mixed lympho-epidermal cell cultures: value in bone marrow grafts].

Graft-versus-host disease (GVHD) is the major complication of allogeneic HLA-identical bone marrow transplantation. GVHD is induced by the activation of mature T cells in the graft which react against minor antigens of the recipient. Mixed epidermal cell-lymphocyte cultures (MELC), which constitute an in vitro model of epidermal cell-lymphocyte interactions, make it possible to study the presentation of antigens to the lymphoid cells by epidermal Langerhans cells. We performed MELC in 66 patients who had received an HLA-identical bone marrow transplant for malignant blood disease. The bone marrow received by 29 recipients had been depleted of mature T cells, whereas 37 recipients had received a non-depleted bone marrow. A complete, uni- and multivariate statistical analysis was carried out on recipients of non-depleted bone marrow to evaluate the risk factors for acute and chronic GVHD. This study showed that MELC between donor and recipient was the most predictive parameter for the occurrence of GVHD. Other factors were a history of previous pregnancies in female donors and a diagnosis of chronic myelogenous leukaemia. These results may be of value in the selection of donors and for a better determination of the need for bone marrow depletion.

Animals↗
PubMed1989

Photosensitization of Wi26-VA4 transformed human fibroblasts by low density lipoprotein loaded with the anticancer porphyrin mixture photofrin II: evidence for endoplasmic reticulum alteration.

Wi26 VA4 cells (SV40-transformed human lung fibroblasts) were incubated with low density lipoprotein (LDL) loaded with the anticancer porphyrin mixture photofrin II (P2). After labelling with 51Cr sodium chromate, cells were exposed to near UV light. After light exposure, kinetics of 51Cr release by cells were studied as a probe of cell damage. The activity of acyl-coenzyme A:cholesterol-O-acyltransferase, a key enzyme of cholesterol metabolism localized in endoplasmic reticulum (ER), was decreased as a function of the irradiation time in cells pre-incubated with P2-LDL. This result suggests that ER alteration occurred during cell photosensitization by P2-LDL.

Cell Line↗
PubMed1989

Synthetic retinoids inhibit the antigen presenting properties of epidermal cells in vitro.

The clinical efficacy of retinoids in benign and malignant skin diseases involving immune mechanisms suggests that they affect the immunologic functions of the epidermis. However, these effects have yet to be demonstrated. The action of vitamin A (retinol) and the synthetic retinoids, isotretinoin, etretinate, acitretin, and arotinoid-free acid have been studied on the lymphocyte proliferation induced by phytohemagglutinin (PHA), by the mixed lymphocyte reaction (MLR), and the mixed epidermal cell-lymphocyte reaction (MECLR). The results for PHA-induced proliferations were highly variable for all the retinoids. However, in MECLR, the synthetic retinoids consistently reduced the proliferation by 20%-30%. This occurred at therapeutic drug concentrations of about 10(-7)M. In MLR, a minor decrease of 10%-15% was only found for higher concentrations (10(-5)M). Retinol induced no effect in either reaction. Further analysis of acitretin on MECLR showed that it reduced lymphocyte proliferation in a dose-dependent fashion. This reduction was combined with a decrease in cytotoxic T-lymphocyte induction (CTL). Addition of 10(-6)M acitretin at various times also revealed that its presence at cell culture initiation was necessary to inhibit proliferation significantly. Furthermore, cell treatments prior to MECLR showed that exposure of epidermal cells to acitretin was essential to produce this inhibition, suggesting that it acts directly on epidermal cells. Consequently, it is suggested that the specific inhibitory effect of synthetic retinoids on lymphocyte activation in MECLR may partly account for their therapeutic action on the skin.

Acitretin↗
PubMed1989

Diagnosis of adult linear IgA dermatosis by immunoelectronmicroscopy in 16 patients with linear IgA deposits.

Homogeneous linear IgA deposits at the dermo-epidermal junction (DEJ) shown by direct immunofluorescence are characteristic of what is termed linear IgA bullous dermatosis. However, it is not yet certain that this disease constitutes an entity distinct from other subepidermal blistering diseases, especially when IgG deposits are also present. Sixty-one cases of subepidermal blistering disease in adults were therefore investigated by immunoelectron microscopy (IEM), and the 16 patients observed to have homogeneous linear IgA deposits were compared with the 45 who had no IgA but had IgG and/or C3. In 11 of the 16 patients with IgA (four of whom also had IgG), the deposits were linear and formed a mirror image pattern on each side of the lamina densa from which they were separated by a clear space. In contrast to this monomorphic IEM pattern, clinical and other laboratory findings were very heterogeneous, making exact clinical diagnosis difficult. Of the remaining five patients in this group of sixteen, three (all with both IgA and IgG) had bullous pemphigoid, epidermolysis bullosa acquisita, and cicatricial pemphigoid, respectively, on IEM and clinical investigation. In the remaining two patients (one with both IgA and IgG, and one with IgA only) the deposits were located in the lamina lucida, making precise classification impossible. None of the 45 patients with isolated IgG and/or C3 deposition displayed the mirror image pattern. We conclude that this IEM pattern may constitute a specific diagnostic criterion of linear IgA dermatosis.

Adult↗
PubMed1989

Influence of human dermal fibroblasts on epidermalization.

Using a method that allowed the reconstruction of simplified living human skin in vitro, we investigated the effects of collagen texture and dermal fibroblasts on epidermal growth. Like in vivo skin, our in vitro model comprised two tissues: a dermal equivalent and an overlying epidermis. It permitted measurement of epidermal growth and therefore evaluation of the effect of the dermal equivalent on this growth. Epidermal growth was enhanced when the collagen matrix had previously been reorganized by fibroblasts, and was greatest when living fibroblasts persisted in this matrix. On cell-free collagen gel and on collagen matrices containing dead fibroblasts, epidermal growth increased when the medium was conditioned by fibroblasts grown in monolayers. We conclude that the function of the fibroblasts is not only to synthesize and degrade the extracellular matrix, but also to regulate epidermalization; on the one hand by remodeling the collagen fibers, and on the other by secreting diffusible factors that promote epidermal growth. These results underline the importance of fibroblasts in dermo-epidermal interactions, and show that the skin equivalent culture model provides a way to quantitatively study these interactions.

Adult↗
PubMed1989

Eosinophilic pustular folliculitis (Ofuji's disease): efficacy of isotretinoin.

The case of a 30-year-old man with a 6-year history of eosinophilic pustular folliculitis (EPF) is reported. Isotretinoin (1 mg/kg/day) led to a dramatic improvement of all the lesions within 2 weeks. The withdrawal of the drug was followed by a recurrence after 10 days of the papulopustular, follicular and pruritic lesions. Reintroduction of isotretinoin was successful. The benefits of isotretinoin in the treatment of EPF have, to the best of our knowledge, never been reported previously. The mechanisms underlying this efficacy may involve the inhibition of the eosinophilic chemotactic factors thought to be present in sebaceous lipids and in the stratum corneum of patients suffering from EPF.

Adult↗
PubMed1989

Biological and cellular responses to grass pollen in sensitive patients.

Using a noninvasive skin chamber technique, we studied the in vivo development of anaphylactic reactions in 8 pollen-sensitive patients suffering from seasonal allergic rhinitis/conjunctivitis/asthma and showing positive cutaneous reactions after intradermal allergen challenge. As agonists, histamine and pollen were introduced into the skin chambers and left in contact with superficial dermis during 6 h. The release of mediators (histamine and prostaglandin [PG] D2) and the modifications in protein diffusion occurring during the immediate (30 min) and the late (6 and 24 h) cutaneous reaction phases were quantitatively analyzed. 24 h after agonist introduction, the recruitment of inflammatory cells on the superficial dermis was studied by use of Rebuck's windows. Histamine release in pollen-containing skin chambers was immediate and persisted until the 24th h despite replacement of the agonists by control medium at the 6th h. An intense PGD2 release occurred as soon as the first 30 min in chambers containing either exogenous histamine or pollen and was maintained until the 24th h. Protein diffusion induced by histamine and pollen was similar to the control one at 30 min but was intensely enhanced at the 6th h. At the 24th h, pollen-induced protein diffusion was still intense whereas that induced by histamine was analogous to the control one. 24 h after pollen challenge, numerous eosinophils were recruited on the superficial dermis but almost none were observed after control medium or histamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Eosinophils↗
PubMed1989

[Viability of new valvular homografts. Myth or reality?].

Use in cardiac surgery of aortic homografts as a valvular substitute is old and was specially developed in France by F. Fontan. In fact, these first allografts were non-viable and the results, in aortic position, were not better than current bioprosthesis. Renewed interest is related to the important notion of "viability" allowed by an immediate procurement (organ donors), preparation in nutrient medium RPMI with low doses of antibiotics and final storage at -196 degrees C (cryopreservation). We have reviewed our initial experience concerning 32 implanted homografts in children either in reconstruction of the right ventricular outflow tract (in many forms of congenital heart disease) or in aortic position. No mortality was observed. The only failure was due to an initial sizing mistake leading to an aortic valve replacement at 13 months. No late deterioration (mean follow-up: 12.5 months) was detected by echocardiography. These results seem to confirm other larger series (as O'Brien's, Brisbane, Australia). Biologic, histological and immunological assessments of "viable" homografts are discussed. The limits of the technique are reported.

Adolescent↗
PubMed1989

[Questions raised by the clinical and biological polymorphism of atopic dermatitis].

AD is not clearly located amongst the diseases of allergy, but it has some common features with respiratory tract allergy. 1. The disregulation of IgE and also T cell abnormalities. 2. Long-lasting inflammatory flare-up of AD resembles more delayed-type mechanisms of hypersensitivity than the precocious immediate type of respiratory allergy. Furthermore, the accumulation of inflammatory cells (PMN and monocytes-macrophages) in the sites involved in AD have not yet been thoroughly investigated. 3. Another feature of AD is its frequent association with respiratory tract allergy, though the immediate type reactions observed with respiratory symptoms are not necessarily linked by common mechanisms to AD cutaneous lesions. 4. Cutaneous lesions that suggest AD are often seen in disorders where there are genetic abnormalities, though in spite of a common eczematous aspect, the etiology and prognosis are entirely different from AD.

Age Factors↗
PubMed1988

Biochemical and morphological modifications in dexamethasone-treated mouse bone marrow-derived mast cells.

Addition of 1 microM dexamethasone (DM) to bone marrow-derived mast cells (BMMC) induced a time-dependent increase in cell histamine content. The latter reached a plateau of 2.5 micrograms/1 x 10(6) cells after 11 days in culture, compared with 100 ng/1 x 10(6) for untreated BMMC. Steroids, such as beta-estradiol, androsterone, and testosterone (1 microM), did not alter the histamine content of BMMC, whereas progesterone (1 microM) induced a moderate increase. Other glucocorticosteroids also enhanced histamine content, suggesting that the observed increase was specific for glucocorticosteroid. Treatment of BMMC with 1 microM DM for 14 days inhibited the Ag-induced, IgE-mediated release of histamine, beta-hexosaminidase, platelet-activating factor-acether, LTB4, and LTC4 by 65 +/- 3%, 66 +/- 1%, 93 +/- 3%, 66 +/- 2%, and 74 +/- 10%, respectively (mean +/- 1 SD, n = 3). In contrast with untreated cells which produce less than 2 ng/1 x 10(6) cells PGD2 after Ag challenge, DM-treated BMMC generated 16.8 +/- 0.3 ng/1 x 10(6) cells PGD2. Moreover, most of DM-treated BMMC became Alcian blue+/safranin+ and by ultrastructure, exhibited numerous cytoplasmic granules filled with abundant and uniform electron-dense matrix. The present results indicate that DM-treated BMMC exhibit biochemical and functional properties different from immature untreated cells, suggesting that a maturation-like process occurred in vitro during DM treatment.

Alcian Blue↗