Primary Photo Processes In Biology And Medicine

Recently there have been major developments in the experimental techniques available for the study of the primary events following the absorption of ultra-violet and visible radiation by biological systems. These techniques, which include absorption, emission, resonance Raman, electron spin resonance, nuclear magnetic resonance and photoacoustic spectroscopies, can be used to study the fate of transient species with lifetimes ranging from seconds to nanoseconds and extending in some cases, such as laser flash photolysis, to pico 12 15 (10- S)- and even femtoseconds (10- s). In parallel with these developments there has been a dramatic increase in the use of light in medicine via the direct photochemical alteration of endogenous molecules (phototherapy) or via the photoactivation of drugs in the skin or other tissue (photochemotherapy). Thus neonatal hyperbili rubinaemia can be routinely treated by phototherapy and psoriasis is frequently treated by PUVA photochemotherapy. A promising new photo chemotherapy used the phototoxicity of porphyrin drugs activated by red light to destroy solid malignant tumors. While some of the overall qualitative effects of such treatments are known, only recently have we begun to understand the associated molecular mechanisms. The primary molecular processes involve short-lived species. The pur pose of this Advanced Study Institute was to review some newer experi mental techniques for the study of such species, the application of these techniques to biological and medical systems and to examine the value of such information in phototherapeutic situations.

Almost all life depends on light for its survival. It is the ultimate basis for the food we eat (photosynthesis), and many organisms make use of it in basic sensory mechanisms for guiding their behaviour, be it through the complex process of vision, or by the relatively more simple photosens itivity of microorganis~urthermore, light has profound implications for the field of medicine, both as a cause of disease (ie UV damage of DNA), and as a therapeutic agent (ie photodynamic therapy). These and other processes are the basis for the science of photobiolog~ which could be defined as the study of the effects of (visible and ultraviolet) light (from both the sun and artificial sources) on living matter. By its very nature, therefore, it is a multidisciplinary science involving branches of biology, chemistry, physics and medicine. This book contains a selection of papers which have been chosen to highlight recent advances in the various disciplines that make up photo biology. Although no book on photobiology can hope to be comprehensive, we hope that this volume includes a representative sample of much of what is new in the field. It is, however, inevitable that some areas will be better represented than others reflecting the biases of conference org anisers and editors.

The first edition of The Science of Photobiology was published in 1977, and was the first textbook to cover all of the major areas of photobiology. The science of photobiology is currently divided into 14 subspecialty areas by the American Society for Photobiology. In this edition, however, the topics of phototechnology and spectroscopy have been com bined in a new chapter entitled "Photophysics." The other subspecialty areas remain the same, i.e., Photochemistry, Photosensitization, UV Radiation Effects, Environmental Photobiology, Photomedicine, Circadian Rhythms, Extraretinal Photoreception, Vision, Photomorphogenesis, Photomovement, Photosynthesis, and Bioluminescence. This book has been written as a textbook to introduce the science of photobiology to advanced undergraduate and graduate students. The chapters are written to provide a broad overview of each topic. They are designed to contain the amount of information that might be presented in a one-to two-hour general lecture. The references are not meant to be exhaustive, but key references are included to give students an entry into the literature. Frequently a more recent reference that reviews the literature will be cited rather than the first paper by the author making the original discovery. The chapters are not meant to be a repository of facts for research workers in the field, but rather are concerned with demon strating the importance of each specialty area of photobiology, and documenting its relevance to current and/or future problems of man.

First multi-year cumulation covers six years: 1965-70.

First multi-year cumulation covers six years: 1965-70.