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Query: UMLS:C0152030 (skin irritation)
 2,146 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The variability in human skin irritation responses has been well documented and can confound our ability to accurately assess differences in skin reactivity between human subpopulations. In the current analysis, results were compiled from nine acute irritation patch test studies, conducted at three test facilities over a 5-year period. Four irritant test chemicals, 20% sodium dodecyl sulphate, 100% decanol, 100% octanoic acid and 10% acetic acid, were tested in sufficient numbers of test subjects to enable the stratification of results for different human subpopulations. An increased reactivity was noted for Asian versus Caucasian subjects for each of three test chemicals, in contrast to the previously described individual study results from which these data were drawn. Male subjects were directionally or significantly more reactive to each of the test chemicals than female subjects. The oldest age cluster of subjects (56-74 years of age) was directionally or significantly less reactive than younger age clusters. There was virtually identical reactivity between self-assessed 'sensitive' and normal skin groups. Lastly, there was little correlation between the results from individual subjects tested in two or more studies with the same chemicals. These results add to our general understanding of population differences in skin reactivity and the potential implications for ingredient and product skin safety testing and risk assessment.
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PMID:Population differences in acute skin irritation responses. Race, sex, age, sensitive skin and repeat subject comparisons. 1191 1

Human head lice Pediculus humanus capitis (De Geer) (Phthiraptera: Pediculidae) are insect parasites closely associated with humans, feeding on the blood of their hosts and causing them skin irritation and probable secondary infections. Despite being a severe nuisance, very few studies have reported on intraspecific chemical communication in head lice. Here, we evaluated the attractive response of head lice to the volatile compounds and solvent extracts from their feces. We also chemically analyzed the main volatile components of these feces and those of the feces' extracts. Head lice were attracted to the methanol extract of their feces but not to the hexane or dichloromethane extracts, suggesting the polar nature of bioactive chemicals present in head louse feces. Follow-up chemical identifications, in fact, showed the presence of hypoxanthine, uric acid, and another purine tentatively identified as either guanine or iso-guanine. Additionally, head lice were significantly attracted by volatiles emitted from samples containing feces. The volatiles emanated from feces alone contained 19 identified substances: 2-pentanone, hexanal, heptanal, 3-methyl-3-buten-1-ol, octanal, sulcatone, nonanal, acetic acid, 2-ethyl-1-hexanol, decanal, 1-octanol, butyric acid, 1-nonanol, hexanoic acid, octanoic acid, 2,6-dimethyl-7-octen-2-ol, 2-undecanone, geranylacetone, and hexadecane. The major compounds found were decanal, nonanal, hexanal, and acetic acid, together representing approximately 60% of the identified compounds. This work represents the first chemical evidence of intraspecies communication among head lice. The results support the existence of active substances present in the feces of P. humanus capitis that may be involved in its aggregation behavior.
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PMID:Head Louse Feces: Chemical Analysis and Behavioral Activity. 3165 19