Fatty Acids of Acylceramides From Comedones and From the Skin Surface of Acne Patients and Control Subjects

Comedonal lipids and skin surface lipids were collected from six acne patients and surface lipids were collected from sex- and age-matched controls without acne. Six series of ceramides were found in each sample, the relative amounts of which were determined by thin-layer chromatography/photodensitometry. Acylceramides (ceramide 1) were isolated by preparative thin-layer chromatography and their ester-linked fatty acids were analyzed by gas-liquid chromatography. The comedonal acylceramides contained higher proportions of 16:0, 16:1Δ6, and 18:1Δ6+Δ8 and much less linoleate (18: 2Δ9,12) than the acylceramides from the skin surface. In the surface lipids from legs, acylceramides from the acne patients contained less linoleate than the acylceramides from control subjects. Free fatty acids from the comedones were also isolated and analyzed, and had a composition very similar to the esterified fatty acids of comedonal acylceramides. The results confirm that fatty acids derived from sebum become incorporated into comedonal acylceramides, displacing linoleate, and show that this process even affects the acylceramides of surface epidermis, more so in acne patients than in normal subjects

Egyptian Architecture and Mathematics

An analysis of the relationship between mathematics and architecture in ancient Egypt requires, first of all, an analysis of the terms involved in the discussion. Mathematics, mathematicians, architecture, and architect are modern terms that convey a range of meanings that may or may not find a precise correspondence in the ancient Egyptian culture. Textual, iconographic, and archaeological sources provide a significant amount of pieces of the puzzle representing the complex task of building a monument, and yet some important aspects still remain unclear. Mathematical knowledge was deeply intertwined with the architectural practice, but defining its nature and boundaries is not easy. The extant mathematical texts are schoolbooks and cast a relatively limited light on the way in which numbers and geometrical figures were used in the planning and building process; in particular, it is difficult to establish who decided the shape and the dimensions of the buildings and of their architectural elements. The overall impression is that building a monument was a collective enterprise, carried out by a long line of individuals, the majority of whom remained anonymous