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Biomedical subjects

L F Patrick

Publications and source records attributed to L F Patrick.

5 recordsLinked to original sources
PubMed1991

Time-dependent decrease in sunscreen protection against chronic photodamage in UVB-irradiated hairless mouse skin.

To determine the time dependence of sunscreen protection against chronic photodamage in hairless mice, the time was varied (0-8 h) between topical sunscreen treatment and UVB radiation exposure. Sunscreen products with labeled sun protection factor (SPF) values of 2, 4 and 8 were evaluated; these values were verified in a guinea pig model for SPF determinations. When applied immediately prior to UVB radiation exposure, these sunscreen products were very effective in prevention of skin wrinkling and tumor formation. Onset of photodamage was delayed, the delay being greater with higher SPF values. However, the sunscreen actives were rapidly lost from the skin surface, and their protective effect diminished strikingly as the time between treatment and irradiation increased. For daily protection against chronic photodamage, this suggests a need for photoprotectants with greater substantivity to achieve a high level of protection throughout the day.

Animals↗
PubMed1987

Role of protein and calcium in stratum corneum cell cohesion.

The work reported here indicates that protein and calcium have roles in stratum corneum cell cohesion. A zwitterionic surfactant, 6-octadecyldimethyl ammoniohexanoate (C18AH), was found to completely disaggregate pig and human stratum corneum into intact, individual cells. This method of disaggregation provided a tool to determine the role of tissue components in cell cohesion. The C18AH disaggregation of pig and human stratum corneum was accelerated by proteolytic enzyme and ethylenediaminetetraacetate (EDTA). The C18AH disaggregation could be blocked by pretreatment of the stratum corneum with the serine-type proteolytic enzyme inhibitor phenylmethylsulfonyl fluoride (PMSF). The blockage could be overcome by addition of proteolytic enzyme or divalent metal ion chelator. These and other data indicate the importance of protein and calcium in stratum corneum cell cohesion.

Animals↗
PubMed1975

Teratology studies of a mixture of tallow alkyl ethoxylate and linear alkylbenzene sulfonate in rats and rabbits.

A mixture of 55% tallow alkyl ethoxylate sulfate (TAE3S) and 45% of linear alkylbenzene sulfonate (LAS) was fed to two generations of rats at dietary levels of 0.1, 0.5 or 1.0%. The rats were fed the surfactant mixture either continuously or during the organogenesis (days 6-15) period of six pregnancies. In addition, pregnant New Zealand rabbits were given 50, 100 or 300 mg/kg doses of the surfactant mixture by intubation on days 2-16 of gestation during a single pregnancy. No adverse effects were noted on conception, fetal viability or post-natal survival in either generation of rats. There were no statistical differences among the groups of rat fetuses taken by Caesarian section and examined for birth defects. Of 1210 rat fetuses, the overall incidence of abnormal young was 9.0%. Similarly, no adverse effects were seen in rabbits treated with the surfactant mixture. Of 855 rabbit fetuses, 5.7% were abnormal, but the incidences of defective fetuses in the test groups were not significantly different from those in controls. Thus, no test related effects were seen on reproduction or embryonic development in either animal species.

Abnormalities, Drug-Induced↗