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Microbial ecology of the gut
294
Reviews of recent publications--fd
a major environmental factor in disease, and how their effects might be predicted and prevented. During its ten meetings the Group discussed the monitoring of health, the effects of environmental lead, the environmental causes of cancer and testing procedures for the identification of carcinogens, the significance of mutagenic and teratogenic chemicals in the environment, sources of exposure to toxic materials in everyday life, the value and limitations of evidence derived from wild life, linkage of records on health, employment and exposure to chemicals, and the major gaps in existing knowledge and research. One of the Group’s most important conclusions was that toxicity testing of new chemicals and drugs tended to be a “sterile routine” of exposure of many animals, without attention to mechanisms. Yet an understanding of toxic mechanisms was essential for any extrapolation of test findings across species and from large doses to levels of human exposure. Nutritional and other variables that could alter susceptibility to toxic effects by an order of magnitude or more were also considered to be poorly understood and little studied. It was thought unlikely that any group of currently available tests for carcinogenicity could provide a quantitative measure of the human risk, and although mutagenicity tests promised to be of value, they needed to be validated by animal studies and correlated with human experience. There was disagreement about the extent to which environmental carcinogens were likely to be industrial in origin, and about the possible importance of other co-carcinogenic factors, and some members thought that research and prevention should be focused on food intake and other aspects of life style. All agreed, however, that the social cost of removing many chemicals from industrial use could be far greater than any potential benefit. The Group regarded existing systems for monitoring trends in human disease as inadequate, and suggested that the Office of Population Censuses and Surveys should monitor not only mortality, as at present, but also other aspects of health such as haemoglobin and cholesterol levels. Improvements were also considered necessary in the current systems of cancer registration and notification of congenital anomalies, and in the health monitoring of industrial workers exposed to new chemicals. To facilitate the detection and measurement of human risks, records of exposure to industrial and other hazards should be linked with hospital discharge and mortality data. Manufacturers should be required to publish toxicity data on compounds about to be marketed, with appropriate provisos to protect patents, and data should also be published on related chemicals that have not been commercially developed, especially when development has been stopped because of toxic effects. It is to be hoped that the conclusions and recommendations of this succinct report will be given serious and immediate consideration by the appropriate authorities. Microbial Ecology of the Gut. Edited by R. T. J. Clarke and T. Bauchop. Academic Press Inc. (London) Ltd., 1977. pp. xvii + 410. f13.50.
Cosmer. T&co/.
Vol. 17, No. 3
The intestinal tract is a complex ecological system. since microorganisms are present not only in a bewildering variety of types but often also in enormous numbers, sometimes 10’“-lO” organisms per gram of gut contents. Allied to this complexity are the difficulties involved in culturing, isolating and identifying the members of the gut flora. Suitable techniques have only recently been developed fully and the opening chapters of this book are therefore devoted to reviews of the methods available for studying gut microbes and to brief descriptions of the various types encountered. The longest chapter in the book is, not surprisingly. on the biochemical activities of the gut flora of several animal species and includes an interesting section on the unusual methods of energy transformation in anaerobic organisms. Although there is a good deal of emphasis on the gut flora of ruminants, the floras of other animals are considered in some detail, and afficionados of the esoteric will no doubt be thrilled by the (albeit short) accounts of foregut fermentations in the hippopotamus and in macropod marsupials such as the quokka. Any attempt to describe the gut flora from an ecological standpoint must obviously consider hostmicrobe interactions. Hence the chapter on the interaction of the hoSt and its microbes, by D. C. Savage. and that on the gnotobiotic animals, by M. E. Coates and R. Fuller, are perhaps the most important and certainly the most fascinating in the book. They also serve to highlight some large gaps in our knowledge of the gut-flora ecosystem. Carcinogenicity Testing: Principles and Problems. Edited by A. D. Dayan and R. W. Brimblecombe. MTP Press Ltd., Lancaster, 1978. pp. xi + 128. f8.95. A short symposium which covered most of the imtesting was portant aspects of carcinogenicity organized in London, at the Royal College of Physicians, in December 1977. An edited account of this meeting has now been published. The topics discussed feature most of the pertinent problems, ranging from the biochemical mechanisms involved in carcinogenicity to long-term and short-term tests to evaluate carcinogenic and mutagenic potential, the cost to industry of screening for carcinogens and last, but not least, the attitude of the UK regulatory authorities. The contributors to the symposium were all experts in their respective fields and their experience has been harnessed into compact, concise chapters which form complete entities in themselves. Each chapter is followed by a short commentary which forms an effective summing up. The central theme is the assessment of carcinogenic hazard, and there is only one chapter concerning carcinogenic mechanisms, a topic that would, in its own right, sustain a complete book. Nevertheless it keys the underlying problem of the number of variables involved in the production, detoxification and removal of carcinogenic molecules to the question of designing tests for carcinogenicity. The conventional long-term tests for carcinogenicity are considered from the point of view of experimental design, pathological interpretation, mathematical analysis and extrapolation of data to man. Con-
Reviews of recent publications--fd
a major environmental factor in disease, and how their effects might be predicted and prevented. During its ten meetings the Group discussed the monitoring of health, the effects of environmental lead, the environmental causes of cancer and testing procedures for the identification of carcinogens, the significance of mutagenic and teratogenic chemicals in the environment, sources of exposure to toxic materials in everyday life, the value and limitations of evidence derived from wild life, linkage of records on health, employment and exposure to chemicals, and the major gaps in existing knowledge and research. One of the Group’s most important conclusions was that toxicity testing of new chemicals and drugs tended to be a “sterile routine” of exposure of many animals, without attention to mechanisms. Yet an understanding of toxic mechanisms was essential for any extrapolation of test findings across species and from large doses to levels of human exposure. Nutritional and other variables that could alter susceptibility to toxic effects by an order of magnitude or more were also considered to be poorly understood and little studied. It was thought unlikely that any group of currently available tests for carcinogenicity could provide a quantitative measure of the human risk, and although mutagenicity tests promised to be of value, they needed to be validated by animal studies and correlated with human experience. There was disagreement about the extent to which environmental carcinogens were likely to be industrial in origin, and about the possible importance of other co-carcinogenic factors, and some members thought that research and prevention should be focused on food intake and other aspects of life style. All agreed, however, that the social cost of removing many chemicals from industrial use could be far greater than any potential benefit. The Group regarded existing systems for monitoring trends in human disease as inadequate, and suggested that the Office of Population Censuses and Surveys should monitor not only mortality, as at present, but also other aspects of health such as haemoglobin and cholesterol levels. Improvements were also considered necessary in the current systems of cancer registration and notification of congenital anomalies, and in the health monitoring of industrial workers exposed to new chemicals. To facilitate the detection and measurement of human risks, records of exposure to industrial and other hazards should be linked with hospital discharge and mortality data. Manufacturers should be required to publish toxicity data on compounds about to be marketed, with appropriate provisos to protect patents, and data should also be published on related chemicals that have not been commercially developed, especially when development has been stopped because of toxic effects. It is to be hoped that the conclusions and recommendations of this succinct report will be given serious and immediate consideration by the appropriate authorities. Microbial Ecology of the Gut. Edited by R. T. J. Clarke and T. Bauchop. Academic Press Inc. (London) Ltd., 1977. pp. xvii + 410. f13.50.
Cosmer. T&co/.
Vol. 17, No. 3
The intestinal tract is a complex ecological system. since microorganisms are present not only in a bewildering variety of types but often also in enormous numbers, sometimes 10’“-lO” organisms per gram of gut contents. Allied to this complexity are the difficulties involved in culturing, isolating and identifying the members of the gut flora. Suitable techniques have only recently been developed fully and the opening chapters of this book are therefore devoted to reviews of the methods available for studying gut microbes and to brief descriptions of the various types encountered. The longest chapter in the book is, not surprisingly. on the biochemical activities of the gut flora of several animal species and includes an interesting section on the unusual methods of energy transformation in anaerobic organisms. Although there is a good deal of emphasis on the gut flora of ruminants, the floras of other animals are considered in some detail, and afficionados of the esoteric will no doubt be thrilled by the (albeit short) accounts of foregut fermentations in the hippopotamus and in macropod marsupials such as the quokka. Any attempt to describe the gut flora from an ecological standpoint must obviously consider hostmicrobe interactions. Hence the chapter on the interaction of the hoSt and its microbes, by D. C. Savage. and that on the gnotobiotic animals, by M. E. Coates and R. Fuller, are perhaps the most important and certainly the most fascinating in the book. They also serve to highlight some large gaps in our knowledge of the gut-flora ecosystem. Carcinogenicity Testing: Principles and Problems. Edited by A. D. Dayan and R. W. Brimblecombe. MTP Press Ltd., Lancaster, 1978. pp. xi + 128. f8.95. A short symposium which covered most of the imtesting was portant aspects of carcinogenicity organized in London, at the Royal College of Physicians, in December 1977. An edited account of this meeting has now been published. The topics discussed feature most of the pertinent problems, ranging from the biochemical mechanisms involved in carcinogenicity to long-term and short-term tests to evaluate carcinogenic and mutagenic potential, the cost to industry of screening for carcinogens and last, but not least, the attitude of the UK regulatory authorities. The contributors to the symposium were all experts in their respective fields and their experience has been harnessed into compact, concise chapters which form complete entities in themselves. Each chapter is followed by a short commentary which forms an effective summing up. The central theme is the assessment of carcinogenic hazard, and there is only one chapter concerning carcinogenic mechanisms, a topic that would, in its own right, sustain a complete book. Nevertheless it keys the underlying problem of the number of variables involved in the production, detoxification and removal of carcinogenic molecules to the question of designing tests for carcinogenicity. The conventional long-term tests for carcinogenicity are considered from the point of view of experimental design, pathological interpretation, mathematical analysis and extrapolation of data to man. Con-