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Biomedical subjects

R M Sayre

Publications and source records attributed to R M Sayre.

51 records · Page 3Linked to original sources
PubMed1979

Performance of six sunscreen formulations on human skin: a comparison.

Indoor and outdoor tests were performed on human volunteers to determine the protection offered by six commercially available products containing single sunscreen ingredients and combinations of ingredients. Indoor solar simulator studies were performed to determine the inherent efficacy of each product, including use of a whirlpool treatment to evaluate the resistance of each product to wash off. The outdoor study included a ten-minute swimming period followed by sunlight exposure. In all tests, the combination of 7% octyl-dimethyl p-aminobenzoic acid ester and 3% oxybenzone was substantially more effective in protecting against sunburn than any other formula tested, including 5% p-aminobenzoic acid (PABA).

4-Aminobenzoic Acid↗
PubMed1978

The correlation of indoor solar simulator and natural sunlight: testing of a sunscreen preparation.

To determine the equivalence of xenon arc solar simulator and natural sunlight test results, the sun protection factor (SPF) for an experimental sunscreen preparation was determined using each light source. The minimal erythemal doses (MEDs) were shown to be equivalent on unprotected skin. It was necessary to supply additional heat to the treated skin prior to solar simulator exposures to obtain comparable SPFs. By careful control of the subjects' environment, natural sunlight effects can be duplicated with a solar simulator.

Dermatology↗
PubMed1977

Bacterial parasite of a plant nematode: morphology and ultrastructure.

The life cycle of a bacterial endoparasite of the plant-parasitic nematode Meloidogyne incognita was examined by scanning and transmission electron microscopy. The infective stage begins with the attachment of an endospore to the surface of the nematode. A germ tube then penetrates the cuticle, and mycelil colonies form in the pseudocoelom. Sporulation is initiated when terminal cells of the mycelium enlarge to form sporangia. A septum within each sporangium divides the forespore from the basal or parasporal portion of the cell. The forespore becomes enclosed by several laminar coats. The parasporal cell remains attached to the forespore and forms the parasporal microfibers. After the newly formed spores are released into the soil, these microfibers apparently enable a mature spore to attach to the nematode. These results indicate that the endoparasite is a procaryotic organism having structural features that are more common to members of Actinomycetales and to the bacterium Pasteuria ramosa than to the sporozoans or to the family Bacillaceae, as previous investigatios have concluded.

Actinomycetales↗
PubMed1977

Occurrence in Monia rectirostris (Cladocera: Daphnidae) of a parasite morphologically similar to Pasteuria ramosa (Metchnikoff, 1888).

Pasteuria ramosa, a bacterial parasite of the cladocerans Daphnia pulex and D. magna, was described by Metchnikoff in 1888. Because the organism could not be cultured, it was subsequently lost. However, the original illustrations and descriptions of the life cycle of P. ramosa are similar to a bacterial spore parasite of nematodes (BSPN) that was recently described in Meloidogyne. As a result of these similarities, a search for P. ramosa was initiated. An organism resembling P. ramosa was found infecting Moina rectirostris, a member of the Daphnidae and a new host for the bacterium. Photomicrographs and scanning electron micrographs of the parasite indicated that the morphology of this organism was similar to the descriptions and illustrations presented by Metchnikoff. Morphological features of this newly described parasite also indicated that the bacterium is similar to the BSPN.

Animals↗
PubMedDate not supplied

Pasteuria thornei sp. nov. and Pasteuria penetrans sensu stricto emend., mycelial and endospore-forming bacteria parasitic, respectively, on plant-parasitic nematodes of the genera Pratylenchus and Meloidogyne.

Descriptions are presented of two members of the Pasteuria penetrans group of mycelial and endospore-forming bacteria, parasitic on plant-parasitic nematodes. In one case, the epithet P. penetrans sensu stricto emend. has now been limited to members of this group with cup-shaped sporangia and ellipsoidal endospores, parasitic primarily on the root-knot nematode Meloidogyne incognita. The second organism, with rhomboidal sporangia and nearly spherical endospores, which is parasitic primarily on the root-lesion nematode Pratylenchus brachyurus, is assigned to P. thornei sp. nov. An updated and emended description is offered of the genus Pasteuria Metchnikoff 1888 emend. The relationships are analysed among these two nematode parasites and the type species of this genus, P. ramosa Metchnikoff 1888, a parasite of cladoceran invertebrates. Because none of these microbes has been publicly reported to have been cultivated axenically, these relationships are based mainly on morphological, developmental, and pathological criteria.

Animals↗
PubMedDate not supplied

Protection against photodynamic therapy (PDT)-induced photosensitivity by fabric materials.

"Special" highly protective fabrics are now available that offer broad-spectrum protection in preventing sunburn, and possibly other types of photodamage. It is important to know to what extent these fabrics are capable of protecting the wearer against skin cancer, photosensitivity disorders, and inadvertent phototoxic reactions from photodynamic therapy (PDT). We assess the ability of one such special (Solumbra) fabric and one "typical" summer fabric to provide protection against PDT phototoxicity produced in tape-stripped Sk-1 hairless mice by topical 5-aminolevulinic acid (ALA) and (primarily) visible light (360-800 nm). Since ALA-derived photosensitizers absorb most of the visible spectrum, results from these studies give a good indication of the photoprotective capability of these fabrics throughout this region. Mice were irradiated dorsally with a Kodak slide projector equipped with a 300 W tungsten-halogen lamp (I0 = 48.3 mW/cm2). After determining the minimal phototoxic dose (MPD) to be 1.40 +/- 0.4 J/cm2, we irradiated the tape-stripped ALA-sensitized mice through the stretched test fabrics with appropriate multiples of the MPD. The special fabric provided protection against 25-30 MPD visible light between 360-800 nm in 14/14 mice. The typical fabric failed to provide protection against 2.5 MPD of the same spectrum. No phototoxic or other adverse responses were seen with either the ALA or light control. In conclusion, the Solumbra fabric is much more protective against ALA photosensitization than the typical fabric. Both appear better at blocking UV than visible light.

Aminolevulinic Acid↗