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R L Dimond

Publications and source records attributed to R L Dimond.

66 records · Page 4Linked to original sources
PubMed1976

Measurement of the staphylococcal epidermolytic toxin: a comparison of bioassay, radial immunodiffusion, and radioimmunoassay.

Three methods of measuring the epidermolytic toxin Staphylococcus aureus-bioassay in newborn mice, radial immunodiffusion, and radioimmunoassay-were compared for reproducibility, specificity, and sensitivity. The bioassay is highly specific and remains the only functional assay. It is reproducible only if newborn mice of the same age are used. The time required for epidermolysis follows a dose-response relationship only if concentrations of toxin large enough to cause peeling in 90 min or less are used. This limits the sensitivity of the bioassay to about 5 mug per ml. Single radial immunodiffusion in agar is a specific and reproducible assay method, but its sensitivity is also about 5 mug per ml. A radioimmunoassay was established by the Farr technique using purified epidermolysin radiolabeled with 125iodine. This assay was highly reproducible and specific. The staphylococcal products, alpha-toxin and enterotoxins A and B, did not cross-react with anti-epidermolysin antibodies. The sensitivity of the radioimmunoassay is 20 ng per ml.

Animals↗
PubMed1976

Purification and characterization of a staphylococcal epidermolytic toxin.

A staphylococcal exotoxin that causes epidermolysis when injected into the skin of the newborn mouse and man was highly purified by coventional biochemical techniques. With Staphylococcus aureus EV, the epidermolytic toxin was a major protein component of supernatant culture fluids. The initial step in purification was zone electrophoresis in Pevikon carried out at pH 9.0, the isoelectric point of alpha-hemolytic toxin, which remained near the origin. Fractions containing the epidermolytic toxin, but free of alpha-toxin, were then subjected to cation exchange chromatography on carboxymethyl-Sephadex C-50 to remove trace contaminants. A major highly purified epidermolytic toxin migrated as a single band in polyacrylamide gel electrophoresis, sedimented as a single component in the analytical ultracentrifuge, and elicited a single precipitating antibody after injection into rabbits. A smaller amount of a second epidermolytic toxin, identical in molecular weight and antigenicity but differing in electrophoretic behavior from the major molecular species, was also identified. The epidermolytic factor had a molecular weight of 28,600 +/- 400 by sodium dodecyl sulfate-acrylamide electrophoresis and 32,500 +/- 120 by approach to sedimentation equilibrium.

Animals↗
PubMed1976

The role of divalent cations in epidermolysis.

In experiments designed to elucidate the role of divalent cations in maintaining the integrity of the epidermis, newborn mouse skin was incubated in ethylenediamine tetraacetic acid (EDTA) or ethylene glycol tetraacetic acid (EGTA). In EDTA, epidermolysis occurred and was confirmed by rubbing the specimen to demonstrate that a sheet of epidermis could be split off. After 30 min incubation in 0-01 mol/EDTA the split occurred in the lower granular-upper spinous layer; after 45 min, it was in a spinous-suprabasilar location and at 60 min and later at the dermal-epidermal junction. Ultrastructurally, a clear zone of apparent intracellular oedema occurred along the cell membranes. The split then occurred intracytoplasmally through this clear zone and the adjacent cell membrane was lost. Since incubation in EGTA at pH 7-4 did not result in epidermolysis, we suggest that the removal of magnesium rather than calcium is responsible for epidermolysis. Thirty min after the addition of either calcium or magnesium to EDTA-treated specimens, epidermolysis could no longer be demonstrated.

Animals↗
PubMed1976

Epidermal nevus and rhabdomyosarcoma.

A child with an epidermal nevus was diagnosed at the age of 15 months as having an embryonal rhabdomyosarcoma of the bladder. This child also had pigmentary abnormalities characteristic of the epidermal nevus syndrome. The question is again asked whether patients with epidermal nevi have an increased incidence of tumors. It is suggested that the thorough evaluation of these patients as recommended by Solomon should also include an alertness for the development of earlier-than-anticipated neoplasms.

Adult↗
PubMed1976

Histology and cytochemistry of human skin. XXXVI. The nose and lips.

The skin of the nose is characterized by often conspicuously dilated openings of the ducts of many subaceous follicles. Histological sections are dominated by gigantic sebaceous follicles, but there are also numerous vellus hairs with small sebaceous glands. All hair follicles on the surface of the nose and in the vestibule are completely invested with nerve end organs. In the vestibule, the glabrous upper surface has intraepidermal nerves and a few mucocutaneous end organs. the vermillion zone of the lip, which seperates the skin of the external lip and the mucosa of the inner lip, is keratinizing glabrous epithelium, often with numerous sebaceous glands in the upperlip. The transitional area between the keratinizing epithelium of the vermillion and the nonkeratinizing epithelium of the labial mucosa is abundantly supplied with mucocutaneous end organs, with only a few in the labial mucosa. The mucoserous glands of the labial mucosa are richly innervated.

Adult↗
PubMed1975

Toxic epidermal necrolysis. Rapid differentiation between staphylococcal- and drug-induced disease.

Based on the difference in the level of epidermal split, staphylococcal-induced toxic epidermal necrolysis (TEN) can be rapidly differentiated from drug-induced TEN. The microscopic pathologic findings of the staphylococcal-induced disease shows epidermal cleavage high in the malpighian layer, while the nonstaphylococcal-induced disease shows a subepidermal split. Rapid differentiation is accomplished by histologically examining a frozen section of peeled skin obtained from a fresh lesion of TEN and by performing a Tzanck preparation on the denuded base. In order to illustrate these techniques, we present the cases of two adult patients with TEN; in one the disease was staphylococcal-induced while in the other it was drug-induced.

Diagnosis, Differential↗
PubMed1975

Studies of the mechanism of epidermal injury by a Staphylococcal epidermolytic toxin.

Experimental animal models of the two forms of toxic epidermal necrolysis have been reviewed: a murine model of staphylococcal-induced epidermolysis and a hamster model of graft-versus-host disease. In the former, a protein exotoxin, epidermolysin, has been purified and characterized. The exotoxin has a molecular weight of approximately 30,000 and causes a split beneath the granular layer. It is effective at 3 times 10(-12) moles. Epidermolysin does not require an intact complement system for its action since B10D2 mice deficient in C5 or mice injected with the decomplementing agent in cobra venom factor were susceptible to its epidermolytic effects. Neither are immunocompetent thymocytes required for the action of the toxin since hairless, athymic adult (nu/nu) mice are susceptible. A few reports of epidermolysis due to an exotoxin of group I Staphylococcus aureus have appeared. This toxin is antigenically different from the exotoxin of group II organisms. A model of drug-induced toxic epidermal necrolysis has been described in hamsters, but the toxic principle released from sensitized lymphoid cells has not yet been characterized.

Animals↗
PubMed1973

Mutations affecting N-acetylglucosaminidase in Dictyostelium discoideum.

A procedure for screening several thousand clones for alterations in a specific gene product was apapplied to mutagenized cultures of Dictyostelium discoideum. Six strains were recovered which had less N-acetylglucosaminidase (EC 3.2.1.30) than the wild type. In addition, we isolated four strains in which the enzyme was temperature-sensitive. The enzyme from one of these strains had an altered substrate affinity.N-Acetylglucosaminidase is present at a low level in cells grown on bacteria and increases up to 10-fold during the aggregation stage of development. The enzyme appears to be essential to maintain migrating pseudoplasmodia of normal size, as shown by the fact that all of the mutant strains which accumulate very little N-acetyl-glucosaminidase formed only small migrating pseudoplasmodia containing less than 10% the number of cells found in the wild-type pseudoplasmodia. The small pseudoplasmodia migrated at less than a third the rate of wild-type pseudoplasmodia and ultimately formed diminutive fruiting bodies. N-Acetylglucosaminidase thus appears to be a developmental enzyme that functions during the migration stage.

Acetamides↗