another in the animal body. The full demonstration of the importance of transmethylation and of its relationship to the metabolism of choline, betaine, creatine, sarcosine, and a number of other methylated substances involved research that extended over a number of years. The discussion forms the subject matter of three of the chapters and requires considerably more than one-half of the book. I...

Most of the positive effects of solar radiation are mediated via ultraviolet-B (UVB) induced production of vitamin D in skin. However, several other pathways may exist for the action of ultraviolet (UV) radiation on humans as focused on in this review. One is induction of cosmetic tanning (immediate pigment darkening, persistent pigment darkening and delayed tanning). UVB-induced, delayed tanni...

Vitamin D, a fat-soluble vitamin naturally present in very few foods, is synthesized when ultraviolet rays from sunlight contact the skin. Research suggests that vitamin D insufficiency may result from lack of exposure to sunlight and ultraviolet-B radiation. Individuals from geographic areas of high latitude and low sunlight exposure may be at increased risk for vitamin D deficiency. Emerging ...

Humans evolved in sunlight and had depended on sunlight for its life giving properties that was appreciated by our early ancestors. However, for more than 40 years the lay press and various medical and dermatology associations have denounced sun exposure because of its association with increased risk for skin cancer. The goal of this review is to put into perspective the many health benefits th...

1 Ultraviolet-B radiation (UV-B, 280-320 nm) was surveyed in a mixed deciduous forest in Maryland, USA, using a Robertson-Berger meter. A smaller number of comparable measurements were made in closed-canopy forests in Chile, Panama, and Washington State, USA, and under two canopies recently disturbed by hurricanes, in Virginia, USA, and Mexico. Simultaneous measurements of photosynthetically ac...

Ultraviolet B (UVB) rays vary with time and season and are the major cause of sunburns. Sunburned skin is a leading risk factor for melanoma and non-melanoma skin cancers. Protection against exposure to UVB rays may be achieved by a combination of various approaches such as use of broad spectrum sunscreen formulations. UV radiations (UVR) absorbed by the skin surface can produce harmful compoun...

Leaf discs from expanding leaves of Rumex patientia L. were exposed to 7 hours of visible plus different levels of ultraviolet radiation in the 290 to 315 nm waveband (UV-B) and then placed in darkness. Leaf disc expansion was reduced and anthocyanin production was increased in discs exposed to moderate or high levels of UV-B radiation when compared to control discs. The possibility that the in...