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Biomedical subjects

G Hausmann

Publications and source records attributed to G Hausmann.

11 recordsLinked to original sources

Immunopathologic study of skin lesions in dermatomyositis.

To determine the phenotype of skin infiltrates in affected and uninvolved skin from patients with dermatomyositis, immunohistochemical studies with 10 murine monoclonal antibodies were carried out on 25 skin biopsy specimens. Dermal infiltrates consisted predominantly of HLA-DR-expressing macrophages and T lymphocytes, especially of the CD4 subset. B lymphocytes, as defined by positive staining for Leu-12, were absent. Epidermal Langerhans cells were absent or decreased in some areas of affected skin but the total number was normal. OKT6+ cells were present in some dermal mononuclear infiltrates in close contact with lymphocytes. We observed reduced HLA-DR positivity of dermal capillary endothelia. These findings are apparently different from dermatomyositis muscle infiltrates but are similar to those in skin affected by cutaneous lupus erythematosus. Our observations support the concept that, in autoimmune diseases, cellular infiltrates may be more organ-specific than disease-specific.

Antibodies, Monoclonal

[The Winer dilated pore].

Dilated pore (Winer) is a not uncommon adnexal benign tumor with follicular differentiation. Clinically the lesion looks like a giant comedo, usually located on the facial area of the elderly. Due to annular elevation of the borders, differential diagnosis needs to be made with basal cell epithelioma and senile sebaceous adenoma. The histology shows a typical infundibular dilatation with subinfundibular atrophy of hair structures. The authors report two typical cases of this badly known but not infrequent lesions.

Adenoma

Control of prostanoid synthesis: role of reincorporation of released precursor fatty acids.

Prostanoid synthesis is limited by the availability of free arachidonic acid. This polyunsaturated fatty acid is liberated by phospholipases and usually is an intermediate of the deacylation-reacylation cycle of membrane phospholipids. In rat peritoneal macrophages, ethylmercurisalicylate (merthiolate) or N-ethylmaleimide (NEM) dose dependently inhibited the incorporation of arachidonic acid into cellular phospholipids, at lower concentrations specifically into phosphatidylcholine. Furthermore, merthiolate could be shown to be a rather selective inhibitor of lysophosphatidylcholine acyltransferase. In contrast, phospholipase A2 activity was not affected over a wide dose range. Consequently, macrophages showed a large increase in prostanoid synthesis (prostaglandin E, prostacyclin and thromboxane) in the presence of both lysophosphatide acyltransferase inhibiting agents. Similar results were obtained with human platelets, in which merthiolate increased the release of thromboxane. Addition of free arachidonic acid also enhanced prostanoid synthesis in macrophages. At optimal concentrations, merthiolate had no further augmenting effect. It is concluded that the rate of prostanoid synthesis is not only controlled by phospholipase A2 activity, but rather by the activity of the reacylating enzymes, mainly lysophosphatide acyltransferase.

Animals

Stimulation of macrophage activity by 12-O-tetradecanoylphorbol-13-acetate.

Treatment of resident murine peritoneal macrophages with 12-O-tetradecanoyl phorbol-13-acetate (TPA) rapidly converted the cells to tumour cytostatic and cytolytic effector cells, as determined by growth inhibition or lysis of T-lymphoma cells (Eb, EL4) in vitro. The effective TPA concentrations were 10(-8) to 10(-7)M. Macrophages became cytotoxic as early as one to two hours after exposure to TPA, and tumour cytotoxicity persisted up to 48 hours. TPA did not interfere with the action of the lymphokine macrophage activating factor (MAF) but acted in synergy with it. Generation of antitumour-active macrophages by TPA was accompanied by other metabolic and functional changes, such as an enhancement of the hexose monophosphate shunt, glucosamine incorporation, RNA and protein synthesis, release of prostaglandin E2, thromboxane and prostacyclin, as well as pinocytosis. These data show that TPA may be a valuable model substance to complement studies of MAF; furthermore, use of TPA may help to clarify the role of activated macrophages during tumour promotion and tumour defense.

Animals