Historical perspective on the use of visual grading scales in evaluating skin irritation and sensitization.

Visual assessment of skin reactions has long been used to evaluate the safety of chemicals and preparations that contact the skin, and to meet regulatory requirements. This article reviews the history of visual grading scales, and the results of investigations into the reliability of the method. Some examples are provided to illustrate the diverse array of protocols that use visual scoring to evaluate skin irritation. Furthermore, as bioengineering methods are developed that can quantitate certain aspects of skin irritant and sensitization reactions, it is important to consider whether such measures should supplement or replace visual assessment. Examples of investigations comparing the outcomes of studies that use visual scoring and those that use bioengineering methods are discussed. These examples provide little evidence that bioengineering measures provide an improvement in overall quality in comparison with current testing methods that rely on visual assessment. In addition, such measuring techniques can add considerably to the complexity of testing protocols. When benefits and cost are weighed in the balance, the visual assessment scales popularized by Draize and others remain an effective, practical method of evaluation.

Preliminary characterization of the normal microbiota of the human vulva using cultivation-independent methods.

The objective of this study was to perform a preliminary characterization of the microbial populations of the normal human vulva. Genomic DNA was isolated from samples of the labia majora and labia minora from four healthy women, and sequences of bacterial 16S rRNA genes in each were determined. The sequences were compared with those of known bacterial species to classify the numerically abundant populations in these communities. Even among this limited number of individuals, the microbiota of the human vulva was found to be quite diverse. Each woman had a distinctive microbiota and no single species was common to all women. The microbiota of the labia majora and labia minora differed, although both had appreciable numbers of lactobacilli and strict anaerobes. A greater diversity of populations inhabited the labia majora compared with the labia minora. The results indicated that the microbiota of the vulva includes populations known to be commensals of the microbiota of the skin, colon and vagina, and is much more complex than previously thought, suggesting that more extensive investigations are warranted.

Increased susceptibility of renal epithelial cells to TNFalpha-induced apoptosis following treatment with fumonisin B1.

Previous studies have shown that tumor necrosis factor alpha (TNFalpha) is involved in the pathogenic events following exposure to fumonisin B(1) (FB(1)), a potent inhibitor of ceramide synthase and sphingolipid biosynthesis. The intimate role of sphingolipid mediators in TNFalpha signaling and cellular death suggests that FB(1) may alter the sensitivity of cells to TNFalpha-induced apoptosis. We tested the hypothesis that FB(1) treatment will increase the sensitivity of porcine renal epithelial cells to TNFalpha. Porcine renal epithelial cells (LLC-PK(1)) were treated with FB(1) for 48 h prior to treatment with TNFalpha. A dose-dependent increase in TNFalpha-induced apoptosis was observed in cells pretreated with FB(1). Cells treated with FB(1) showed increased DNA fragmentation and terminal uridine nucleotide end labeling in response to TNFalpha treatment. FB(1) increased DNA synthesis and resulted in cell cycle arrest in the G(2)/M phase of the cell cycle. Flow cytometric analysis of the cell cycle indicated that TNFalpha predominantly killed cells in the G(2)/M phase. The activation of JNK, a mitogen-activated protein kinase (MAPK), was increased following 48 h exposure to FB(1). Phosphorylation of p38 and ERK remained unchanged following treatment with FB(1). FB(1) also increased free sphingoid base levels under identical treatment conditions. Results suggest that FB(1) increased free sphingoid base levels and the population of cells in the G(2)/M phase. This population was shown to be most susceptible to TNFalpha-induced apoptosis. Phosphorylation of pro-apoptotic JNK may play an important role in these effects.