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Biomedical subjects

L Dubertret

Publications and source records attributed to L Dubertret.

At least 289 records · Page 16Linked to original sources
PubMed1986

A possible predictive test for graft-versus-host disease in bone marrow graft recipients: the mixed-epidermal cell-lymphocyte reaction.

The possible ability of the mixed-epidermal-cell-lymphocyte reaction (MECLR) to detect alloreactivities in HLA-identical MLR negative siblings has been investigated before grafting in 30 donor-recipients pairs and their families. Results indicate that recipients' epidermal cells (EC) can induce proliferative responses of HLA-identical MLR-negative donors' lymphocytes in 55% of the pairs tested. Moreover, further evaluation of 21 patients shows that the positivity of the MECLR before the graft is correlated with later appearance of acute and chronic GVHD, and especially with the severity of cutaneous injury. EC have been shown to be more efficient antigen presenting cells than peripheral blood lymphocytes for in vitro primary proliferative responses, so these reactions could be directed against some minor histocompatibility antigens, thus leading to possible improvement in selecting bone marrow graft donors and to the detection of donor-recipient pairs with a high risk of GVHD.

Adolescent↗
PubMed1986

Transfer of melanosomes in a skin equivalent model in vitro.

The transfer of pigment granules from melanocytes to keratinocytes was studied using a new living skin equivalent (SE) model in vitro. The model was constructed by plating human neonatal melanocytes onto a dermal equivalent (DE) before it was overgrown with keratinocytes. The dermal component of the SE arises in vitro through the action of fibroblasts, which compact matrix proteins into a tissue. It becomes keratinized as keratinocytes migrate out of 2-mm punch biopsies of human neonatal skin embedded in the DE; keratinocytes from the biopsies covered the lattice in 14 days. A basal lamina develops at the dermal-epidermal junction in vitro. Exposure of some SEs to UVB irradiation for 14 days stimulated and enhanced pigment transfer. Pigment transfer from melanocytes to keratinocytes was documented in light and electron microscopic studies. Melanosomes, identified by their pigment as well as by dopa oxidase staining, were dispersed throughout the keratinocyte cytoplasm. We conclude that the SE model is valuable for studying the relationship between melanocytes and keratinocytes in vitro; since the SE has been shown to serve as a skin replacement, pigmenting it may be expected to increase its usefulness.

Biological Transport↗
PubMed1986

A new method for studying epidermalization in vitro.

A new method for studying epidermalization in vitro is described. It consists of inserting a punch biopsy that serves as a source of epidermis into dermal equivalent freshly made up, with fibroblasts mixed in a collagen matrix. Fibroblasts cling to collagen fibrils and contract the matrix, leading in 3 days to a resistant dermal equivalent holding the punch biopsy firmly in place. At day 5, a culture medium favouring epidermal growth was used and a fringe of a new epidermis appeared around the punch, the area of which grew linearly with time. This new epidermis showed a pattern of differentiation similar to epidermis in vivo, with cuboidal basal cells, keratohyalin granules, membrane coating granules and the expression of the 65-67 kd keratin subset. The method seems to combine the advantages of the explant technique and of classical keratinocyte cultures, providing the researcher with a large quantity of differentiated epidermis, the pharmacologist with simple and quantitative system in which to study modifications of growth and differentiation of epidermis, and the plastic surgeon with a possible material for skin grafting.

Biopsy↗
PubMed1986

Mixed epidermal cell-lymphocyte reaction in prediction of acute graft-versus-host disease in bone marrow recipients.

Peripheral blood lymphocytes (PBL) and epidermal cells (EC) of 44 patients to be grafted with bone marrow from an HLA-identical sibling have been used as stimulator cells in primary cultures with effector PBL of one or several potential donors. Proliferative responses against PBL did not differ from those obtained with effector cells cultured in medium alone, whereas EC induced clearly positive proliferation in 21/53 (40%) of the pairs tested. Evaluation of 30 patients followed for more than 3 months after the graft shows that a high level of response in the mixed epidermal cell lymphocyte reaction is directly correlated with the incidence of acute graft-versus-host disease.

Acute Disease↗
PubMed1986

Depletion of histidine and tryptophan serum levels in porphyria cutanea tarda and congenital erythropoietic porphyria patients after irradiation with visible light.

We have studied the photosensitized oxidation, via singlet oxygen production, of histidine (His) and tryptophan (Trp) in the serum of porphyria patients and in the serum of healthy volunteers before or after addition of hematoporphyrin. It was observed that free plasma His and Trp are good probes of singlet oxygen production in the blood under visible light irradiation. However, Trp, which is mostly bound to serum albumin, is much less susceptible to photooxidation than His, which remains free in the plasma. These results must not be ignored in systemic effects of porphyrias and in photochemotherapy with hematoporphyrin derivatives.

Blood↗
PubMed1985

Psoriatic fibroblasts induce hyperproliferation of normal keratinocytes in a skin equivalent model in vitro.

A skin equivalent model has been used to fabricate tissues with psoriatic and normal cells. Psoriatic fibroblasts can induce hyperproliferative activity in normal keratinocytes. The psoriatic epidermis from lesions continues to proliferate at high rates for at least 15 days in this model, and normal fibroblasts are unable to suppress this hyperproliferation. The primary defect in psoriatic skin may reside in the dermal fibroblast.

Adult↗
PubMed1985

Lichen planus pemphigoides: an immuno-electron microscopic study.

We report a case of lichen planus pemphigoides. Immuno-electron localization of G-immunoglobulin and C3 showed that in the peribullous zone these were in the lamina lucida, as in typical bullous pemphigoid, but in the bulla itself they were along the floor, and not along the roof as in bullous pemphigoid. We conclude that bullous pemphigoid antigen and lichen planus pemphigoides antigen have different localizations.

Adult↗
PubMed1985

Maintenance treatment of psoriasis by Tigason: a double-blind randomized clinical trial.

Extensive lesions on 36 patients with psoriasis were treated by Tigason, I mg/kg/day plus PUVA until skin clearance. A clinical score was calculated for each body area, and erythema, scaling, thickness and pruritus of the lesions were scored from 0 to 3. Skin clearing was defined as a clinical score less than 10% of the initial score. Double-blind maintenance treatment was then started. This was Tigason at half of the maximal dose tolerated during the clearing phase of the treatment v. placebo. Relapse of the disease was defined as the occurrence of a clinical score greater than 50% of the initial score. Among the 36 patients randomized, 20 received placebo and 16 received Tigason. Relapses increased quickly in the patients on placebo, but occurred in few patients treated by Tigason with 60% remaining clear after 1 year (P less than 0.05). Surprisingly, the kinetics of disappearance of the most frequent side effect, cheilitis, was the same in the Tigason group and in the placebo group. This double-blind randomized clinical trial shows that Tigason at low doses is an efficient and well-tolerated maintenance treatment of psoriasis.

Adult↗
PubMed1985

Involvement of macrophages in the pathology of toxic epidermal necrolysis.

In toxic epidermal necrolysis (TEN), as in the 'epidermal type' of erythema multiforme, the necrotic epidermis is infiltrated with mononuclear cells. We studied the epidermal infiltrate in seven cases of TEN. About half the cells obtained from pieces of cleaved epidermis dissociated by trypsin were non-epithelial. On cytologic analysis, 80% of these foreign cells exhibited markers of macrophages, 15% were granulocytes and only 5% were lymphocytes (almost exclusively OKT8 T lymphocytes). Semi-thin sections of early prenecrotic lesions showed exocytosis of mononuclear cells within the epidermis with features of satellite cell necrosis and formation of colloid bodies. Almost all these mononuclear cells were macrophages as evidenced by endogenous peroxidase-positive granules. These findings suggest that some kind of macrophage-mediated cytotoxicity may play a role in the necrosis of epidermal cells during TEN.

Adolescent↗
PubMed1985

The effect of anthralin (dithranol) on mitochondria.

The short-term effect of topical application of anthralin (dithranol) on normal human skin was investigated by electron microscopy. Mitochondria appeared markedly damaged. By contrast other cellular structures, particularly the nuclear and cytoplasmic membranes were unchanged. In vitro experiments were therefore performed on isolated rat liver mitochondria and it was shown that anthralin acts as an uncoupler of oxidative phosphorylation. These results suggest that anthralin can inhibit the adenosine triphosphate supply in epidermal cells. This loss of energy supply in keratinocytes could explain, at least in part, the therapeutic efficiency of anthralin in psoriasis.

Animals↗
PubMed1985

A simple method for studying chemotaxis, vascular permeability and histological modifications induced by mediators of inflammation in vivo in man.

A new method is described allowing the quantitative and kinetic analysis, in vivo in human skin, of the chemotaxis of inflammatory cells, of the modifications of vascular permeability and of the histological and cytological events induced by certain mediators of inflammation. In order to illustrate the usefulness of the method, the effects of chronic contact to human skin of two potent mediators of inflammation, LTB4 and Paf-acether, are described.

Capillary Permeability↗