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FUNDAMENTALS OF RADIOBIOLOGY
2. M. Bacq, Professor in the University of LiBge, and Peter Alexander, Chester Beatty Research Institute, Institute of Cancer Research, Royal Cancer Hospital, London. Academic Press, Inc., New York, 1955. xii + 389 pp. Figs. and tables. 14.5 X 22 cm. 56.50. BECAUSEradiation biology includes such a variety of phenomena, it is difficult t o d e h e its limits as a particular field of research or specialization. Certainly, however, our knowledge of the complex series of events induced by absorption of ionizing rediation in living systems-from the primary radiation interaction to the ultimate hialogiesl response--must necessarily depend on the collaborative research efforts of the physicist, chemist., and hiologist. It is necessary, too, that from time to time an attempt he made to bring the entire field into focus and t o correlate the information obtained in the various fields of radiation research. Thirr is difficult task as witnessed by the faet that few have attempted it. Lea's "Actions of Radiation on Living Cells" provided a view of the subject as it appeared to a physioist up to World War 11. The present volume, written by a physical chemist and a biologist in collaboration, gives us a review of the field to date. The &st four chapters present asurvey of radiation physics and basic processes of radiation chemistry for solid, liquid, and gaseous systems. Considerable space is given to recent studies of reaction mechanism in the radiation chemistry of water, of aqueous solution, and of mscromaleeulcs, both synthetic and natural. Radical formetion in water, reactions of water radicals with dissolved materials, reactions induced by direct interaction with organic material, and the mechanisms of energy transfer are treated. Some of the mare general concepts of radiation effects in biological systems are developed in terms of the fundamental processes of radiation chemistry. For the most part, these chapters give a straightforward account of current ideas, and are concise yet informative. Chapters 5 and 6 are devoted to the subject of chemical changes in the nuclei and protoplasm of irradiated cells. In a discussion of radiation-induced chromosome hrenhage, the viewpoint is developed that injury cannot be interpreted solely on the basis of a direct action of radiation. The authors conclude that the experimental evidence strongly supports the idea that an indirect action involving biochemical intermediates is involved and may be a predominant factor. They emphasize here, however, that ". . .it cannot (therefore) he concluded that any effect which can be protected against by the addition of chemicals must invariably be the result of reactions with free radicals produced in the surrounding medium!' This fact which has long been reeognieed both in photochemistry and radiation chemistry has often been overlooked in interpreting- ~roteetive action in biological . systems. Chemical substances which simulate the biological effects of radiation are discussed in Chapter 7. The effects of these (radiomimetric) aeents me described in terms of their mutaeenic-.
are recent studies of the relationship between chemical structure of such agents and their biologicel activity. Possible mechanisms of action me considered on the basis of recent work which indicates that many of the r~diamimetricsubstances axe alkylati ing agents containing two or more functional groups. Chapter 8 is devoted to a discussion of the effeete of oxygen on
radiation biological phenomena. Although the faet that arganisms become more resistant to radiation a t low oxygen pressure was first reported over 30 years ago, i t has been only within the last 10 years that the effect has been considered in detail. Interest in this phase of radiobiology was reawakened primarily as a result of the findings in radiation chemicd studies of water and aqueous solution. The authors point out that, although oxygen may influence a biological response induced by direct interaction, it is generally assumed that an oxygen effect is one of thestrongest pieces of evidence for the view that indirect action plays a predominant part in produoing lesions. A large number of detailed publications on this subject are reviewed. Difficulties associated with the study of mammals a t low oxygen pressures are discussed as are the possible practical aspects of the oxygen effect in rsdiation therapy. The remainder of the book is devated primarily to the subjects of radiation protection and the treatment of radiation sickness. Considerable space is devoted t o an informative discussion of the role of sulfhydryl compounds in radiohiachomistry. The authors emphasize that, although (1) -SH groups in simple campounds and in various enzymes me preferentially oxidized in uitro, and (2) many -SH derivatives (cysteine and cystamine) protect against radiation, there is, nevertheless, no evidence that -SH oxidation represents the lesion produced by ionizing radiation in uivo. I n developing a theory of the physicochemical mechanisms of radiohiology, the authors place oonsiderahle emphasis on the importance of H02radical reactions in vlvo. A similar view baa, of course, been expressed by others elsewhere. The main point here, however, is t h a t the authors purport to show on the basis of results obtained from radiation chemical atudies that specific reactions for HOz e m be descrihed, and that this information provides a basis for interpreting certain biological effects. Although this is not the appropriate place far a. discussion of the specialized concepts involved, it should be emphasized, nevertheless, that objections may he rai~isedto a number of the conclusions which are presented. This book is, however, an outstanding accomplishment. In i t the authors have been remarkably successful, considering the inherent difficulties imposed by the subject matter itself, in attaining their professed goal which was to present the phenomena of radiation biology as an integrated whole. WARREN M. GARRISOU
U N I V E R B IOF T ~CALIBORNI* B ~ n a s ~ s Cr ~. L r s o n N r A
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REFLECTIONS OF A PHYSICIST
P. W. Bridgman.
Second edition. The Philosophical Library, New York, 1955. 576 pp. 15 X 22 cm. 56. THIBsecond edition of the well known 1949 collection comprises the hulk of the non-technical writing of Dr. Bridgman. Ten papers have been added. All of these have appeared in print before, but the advantage of finding them in the one-volume collection is reason enough far the issuance of a second edition. Dr. Bridgman has maintained his "operational point of view." Those students of the relationships between science and society particularly will be interested in his 1954 analysis of The Task Before Us and Some Implications of Recent Points of View in Physics. W. F. K.
