The present paper demonstrates the increased photostability of isotretinoin when loaded in microemulsion. The photodegradation of isotretinoin, in methanol and microemulsion formulation was studied under direct sun light. The photodegradation process was monitored by UV spectrophotometry. In methanol solution, isotretinoin undergoes complete photodegradation just within a few minutes of light e...

August 2005 | Volume 3 | Issue 8 | e286 | e281 According to folklore, Polynesians originated from a mythical homeland called Hawaiki. The existence of such a place, however, as well as its location, has been the subject of much speculation. Signifi cant research efforts have attempted to elucidate these claims through archeological, linguistic, and, more recently, biological evidence. Jean Trej...

Shine a flashlight on a black hole, and one is greeted with the return of a series of concentric rings of light. For a point source of light, and for perfect alignment of the lens, source, and observer, the rings are of infinite brightness (in the limit of geometric optics). In this manner, distant black holes can be revealed through their reflection of light from the Sun. Such retro-MACHO even...

The emergence and evolution of life on our planet was possible because the sun provides energy to our biosphere. Indeed, all life forms need energy for existence and proliferation in space and time. Light-energy conversion takes place in photosynthetic organisms that evolve in various environments featuring an impressive range of light intensities that span several orders of magnitude. This pro...

leaf N concentration and content, and relative leaf absorbance (αr) were measured in 1-year-old seedlings of shade-intolerant Betula papyrifera Marsh., moderately shade-tolerant Quercus rubra L. and shade-tolerant Acer rubrum L. Seedlings were grown in full sun or 26% of full sun (shade) and in ambient (350 ppm) or elevated (714 ppm) CO2 for 80 days. In the shade treatments, 80% of the daily PP...

The pl gene encodes a regulatory protein that controls the transcription of a number of structural genes of the anthocyanin biosynthetic pathway in maize. pl alleles have been classified phenotypically into two categories: dominant (Pl) alleles lead to intense, light-independent pigmentation in vegetative and floral organs of the plant; recessive "sun-red" alleles (pl) lead to light-dependent r...

Considerable evidence indicates that vitamin D may reduce the risk of several cancers, including breast cancer. This study examined associations of breast cancer with sun exposure, the principal source of vitamin D, and vitamin D receptor gene (VDR) polymorphisms (FokI, TaqI, BglI) in a population-based case-control study of Hispanic, African-American, and non-Hispanic White women aged 35-79 ye...

We do not read an article that can make us change practice very often. “Vitamin D deficiency in children and adolescents submitted to hematopoietic stem cell transplantation” by Campos DJ from the Curitiba Pediatric Transplantation group is one of these articles.1 Although vitamin D deficiency has been the theme of many publications in the last few years,2 Brazilians would tend to disregard it ...