959
pharmacologists. The past decade, however, has seen an awakening of interest in the condition and an improvement in both the quantity and the quality of research. Many important and interesting, but still unsolved, problems connected with the disease have emerged, and its economic and financial consequences are only now beginning to be understood. Moreover, the emergence of penicillin-resistant, -lactamase-producing gonococci has called into question world-wide antibiotic policies, especially the ease with which antibiotics can be obtained without prescription in many countries. This excellent book contains most of what is known of the subject. It is invaluable for all those who treat patients with sexually transmitted diseases, and should be read by postgraduate students in this subject ; it is also an excellent reference book for epidemiologists, physicians in other branches of medicine, and microbiologists. The text is precise, clearly written, and lightened from time to time by Dr Morton’s attractive sense of humour; besides being easy to read it is illustrated by helpful photographs and tables. Each chapter ends with a full list of references. The best sections of the book are those on the history of gonorrhoea, gonococcal septicaemia, and the size and nature of the problem gonorrhoea poses. In his concluding chapter on the control of gonorrhoea, Morton is pessimistic; he believes that modem social, behavioural, and medical trends will result in a high prevalence of the disease for the rest of this century at least. Politicians, health administrators, and all those who plan and
Reviews of Books
Abortion MALCOLM POTTS, PETER DIGGORV, and JOHN PEEL. London and New York. Cambridge University Press. 1977. Pp. 575. 17.50
(paperback 3.95). THIS is a valuable and extensive review of abortion throughout the world and over the course of time. It has a British bias because of the origin of the authors; the sociological evidence is interesting and well analysed; and the book has a uniformity of style and approach. Those who have followed the abortion debate will know from the names of the authors the sort of conclusions which will be reached. They have convinced themselves of the necessity for abortion, judiciously used with contraception, and they wish to convince others of the validity of their case, stated in elaborate detail which is difficult to find in summary elsewhere. Their case is convincing, though that will not be conceded by everyone. They try hard to do justice to their opponents, but Roman Catholic theologians and some doctors are criticised severely, and sometimes with conscious cleverness. This will not rout the dissenters who, nevertheless, should listen to this generally well argued exegesis. Abortion has been used by all societies. It has been, and is a problem which will not go away. Whether society, through its legislators, lawyers, doctors, and moralists, welcomes termination of pregnancy or rejects it is of small consequence. Many women and their helpers have made their decisions known in action, and the evidence is clearly documented here that abortion will probably remain a feature of fertility control for some time to come. The reader can like it or lump it, but if at the moment he can only lump it because of what, to him, are important ethical considerations, then this book may help him to define those more closely and compare them with those of others. There is fodder for all sides of the argument, but interpretation depends on many inexplicit factors not necessarily amenable to reason. Sir Thomas Browne might be allowed the last word on what it is all about. "As Reason is a Rebel unto Faith, so Passion unto Reason: as the propositions of Faith seem absurd unto Reason, so the Theorems of Reason unto Passion, and both unto Reason". Exactly. So the debate must continue, but with the hope that it will be conducted at the high level of tolerance shown in this book. The authors’ bouts of passionate polemic, comparatively rare, might be overlooked in the same spirit.
Gonorrhcea R. S. MORTON, F.R.C.P.E., The Royal Infirmary, Sheffield. London and Philadelphia: Saunders. 1977. Pp 292. [,10.
has risen
the past twenty than 250 000 000 mfections with gonorrhoea a year throughout the world. Control measures have clearly failed. The disease has, until lately, THE incidence of
gonorrhoea
years and it is estimated that there
been neglected by
over
are more
physicians, microbiologists, epidemiologists,
51 Nielsen, K.H., White, R.G.Nature, 1974, 250, 234. 52 Pepys, M. B. ibid. 1972, 237, 157 53 Pepys, M.B J. exp.Med. 1974, 140, 126. 54 Pepys, M.B. Transplantn Rev. 1976, 32, 93. 55 Pepys, M. B., Brighton, W. D., Hewitt, B. E., Bryant, D. E., Pepys, J. Clin. exp.Immun.1977, 27, 397. 56 Crane, C. G., Rowley, M. J., Warburton, M. F., Mackay, I. R. Clin. Sci. 1972, 43, 869. 57 Papamichail, M., Gutierrez, C., Embling, P., Johnson, P., Holborow, E. J., Pepys, M.B.Scand. J.Immun. 1975, 4, 343. 58 Terry, R. J., Freeman, J., Hudson, K. M., Longstaffe, J. A. Trans. R. Soc. trop Med.Hyg. 1973, 67, 263. 59 Diamantstein, T., Keppler, W., Blitstein-Willinger, E., Ben-Effraim, S. Immunology, 1976, 30, 401.
health-care services should heed his words and ensure that modern facilities for diagnosis and treatment are available, including contact tracing and improved health education.
Medical Selection of Life Risks R. D. C.
1977.
BRACKENRIDGE,
F.R.C.P.E.
London: Undershaft Press.
Pp. 765.[15.
WHILST most doctors frequently fill up forms on their patients for the benefit of life-insurance schemes, few have much idea of what happens next-or how the risk is calculated. The insurance companies turn in healthy profits and few become bankrupt, so their methods must be efficient from a business point of view. Dr Brackenridge’s survey of the medical side of life insurance is an up-to-date and well-written account of how risk is calculated. Since his first review 15 years ago the results of many long-term epidemiological studies concerned with mortality risk have made a reference manual for the insurance medical officer a necessity-and this book is it. However, it is also relevant to other disciplines. The first part of the book deals with the principles of selection and the rating systems used by insurance medical officers on "substandard" lives. The second part provides a detailed analysis of the prognosis of a wide spectrum of treated and untreated disease-each section ending with practical advice to the examining doctor as to how to assess the risk. Despite the fact that there is a measurable difference between the mortality of "insured lives" (upon which most of the vital statistics presented are based) and that of the general population, the book provides a useful reference for people concerned with prospective surveys of mortality and morbidity and the review of world literature appears comprehensive. For this reason too, clinicians will find useful tables of prognostication to compare with their own experience and to help in advising patients and their relatives of the likely outcome of particular diagnosis and operations. The statistics apply to groups of patients, and the art is knowing how to apply them to the individual case. To help the clinician the author includes between the tables and the risk-rating paragraphs, good clinical sections on each disease, highlighting the prognostic features. His philosophy with regard to minor ailments and their relationship to the whole patient is stimulating and his attitude towards stress-related illness enlightened. The book is well presented; and the tables, with one or two exceptions, are easy to understand, and there is a comprehensive index.
960 Haemostasia British Medical Bulletin: vol. XXXIII, no. 3. Edited by DUNCAN THOMAS. London: British Council. 1977. Pp. 292. 4.50 ([,5 over-
seas). THE British Medical Bulletin usually provides nourishing fare, and the September, 1977, issue is no exception. Here, the normal haemostatic mechanism and some of its major disorders have been reviewed. The number of reviews on haemostasis and thrombosis has swelled from a trickle to a flood in recent years. This collection of essays on haemostasis is too brief for the specialist, but it does provide useful information for non-specialist biochemists and clinicians with an interest in haemostasis and thrombosis. The first four chapters, which deal with the platelet and its abnormalities, start with a reminder by J. F. Mustard and M. A. Packham of the extent to which major research in platelet biochemistry is carried out overseas. This is followed by a section on coagulation where Dr Esnouf has had the herculean task of reviewing the biochemistry of coagulation in one chapter; but he has had to omit large quantities of important information (for example, the nature of the different types of thrombin). Professor Bloom has given a good account of the different theories on the nature of factor vm, whilst the fibrinolytic mechanisms have been well covered by Dr Kernoff and Professor McNicol. Dr Rizza is on firm ground whilst writing about the clinical management of haemophilia although, clinicians will feel the need for further discussion on the use of prothrombin concentrates for the treatment of factor-viii inhibitors. Useful, clinically oriented chapters are provided by P. T. Flute, G. 1. C. Ingram, S. J. Urbaniak, and J. D. Cash, whilst A. A. Sharp emphasises the difficulty of evaluating treatment in disseminated intravascular coagulation. The final chapter by T. W. Meade and W. R. S. North is an important attempt to apply epidemiological techniques to haemostatic variables. The chief conclusion would seem to be that factors affecting haemostasis are indeed variable, thus confirming observations that levels of factors vin and v and results of tests of fibrinolysis and platelet function do fluctuate within an individual. It is probable that more accurate detection of individuals at risk for thrombotic diseases may require studies of activated clotting factors, or components derived from platelets, as well as turnover studies.
wards an extreme mechanistic interpretation of behaviour, this is an excellent book, superbly produced and illustrated, and packed with thought-provoking facts. It will be invaluable for those interested in the electrical and molecular basis of neuro-
physiology. Current Respiratory Care Edited by KENNETH F. MACDONNELL and MAURICE S. SEGAL. Boston: Little, Brown, Beckenham: Quest. 1977. Pp. 489.
$14.50,[9.60. THIS book consists of specialist essays on selected aspects of respiratory medicine. The aim is to inform physicians, anasthetists, physiotherapists, and nurses of each others’ specialised activities in the care of respiratory patients. Theoretically, this is excellent but in practice some of the chapters demonstrate that the gulf between members of the respiratory team is uncomfortably wide--can the average nurse or physician be expected to understand the intricate workings of a mechanical ventilator, for example? The essays are based on a postgraduate course on respiratory therapy held annually at Tufts University. The style varies widely between the various contributions, and so does the intellectual demand made by them. Some of the chapters are very valuable, and indeed unique among textbooks. One example is the contribution on sputum, with the problems it brings to respiratory therapists. Other contributions are very sketchy, and it seems pointless to include them when so many others cover the same subject in more detail and more clearly (examples include the immunological contribution and some of the purely descriptive clinical essays). The value of the book lies mainly in the detailed descriptions of many techniques involved in respiratory care, particularly those associated with mechanical ventilation. Unfortunately, several commonly required techniques are not fully covered; bronchoscopy is dealt with rather summarily, with no mention of the segmental anatomy, and techniques such as pleural aspiration and biopsy do not receive attention. Nevertheless, the book contains many items of great interest and can be recommended, particularly to those concerned with the intensive care of respiratory patients. Advanced Medicine 13 1977.
An Introduction to Behavioral Neurobiology. ERIC R. KANDEL. San Francisco: Freeman. 1976. Pp. 727.$45.
THE first
chapter of this book claims that "an effective biology of behavior can best be achieved by concentrating on a specific organism". The organism selected is Aplysia californica, a marine mollusc in which the approach central
to
cellular
nervous
system consists of
by G. M. BESSER. Tunbridge Wells: Pp. 497. £ 8.50.
Edited
Cellular Basis of Behavior
no more
ganglia containing relatively large
nerve
than cells.
a
series of
Compared
with vertebrate nerve cells, the mollusc neurons are simple structures; in many cases their specific interconnections can be readily determined. Moreover, cells can often be individually identified, making it possible to study the same neuron in individual animals under different conditions. This and other features make Aplysia especially suitable for the study of inter-ceii connections and for relating types of neuronal circuits with types of activity. A large part of the book is devoted to detailed descriptions of Dr Kandel’s own research; he has shown, for example, how motor and sensory circuits interact to control feeding, locomotion, and defensive reflexes. But are these basic activities "behaviour"? Kandel is in no doubt: "... the contraction of muscles, changes in visceral tone, and secretions of the glands are the basic elements of observable behavior. They are the only aspects of mental processes that can be studied directly." Others may feel that the complexity of behaviour in man and higher animals, while founded on the basic elements, ultimately requires explanation in different terms even at the level of neurophysiology. But apart from this bias to-
Pitman Medical.
THIS book is the latest in a series published by the Royal College of Physicians. The editor’s aim is to review, in an easily assimilable fashion, areas in medicine of general interest to clinicians in which there has been recent growth. Professor Besser has succeeded and this book is a pleasure to read. Neur-
ology, oncology, endocrinology, genital medicine, cardiorespiratory medicine, and gastroenterology are well covered. There also sections on new methods and treatments. This book must for doctors preparing for higher examinations, while experienced doctors who read it will find themselves repaid, The high standard of medical writing should encourage other authors to pay more attention to presentation and style. are
is
a
New Editions Current Therapy 1977-Edited by Howard F. Conn. and London: Saunders. 1977. Pp. 986.$24.50; k20.25.
Philadelplua
A Short Textbook of Surgery--4th ed. By Selwyn Taylor and Leonard Cotton. London: Hodder & Stoughton. 1977. Pp. 634. ’.4
(paperback 3.95). The Shorter Bergey’s Manual of Determinative Bacceriolog.B8!h ed. Edited by John G. Holt. Baltimore: Williams & Wilkins. London Quest. 1977. Pp. 356.$15.95; 10.55. Fundamentals of Obstetrics & Gynaecology: vol. I, Obstetrics-B Derek Llewellyn-Jones. London: Faber & Faber. 1977. Pp. 471. 1, kQ
(hardback 12).
961
THE.LANCET
Hyperviscosity
in Disease
Two years ago we reviewed the factors which influence blood viscosity in health and diseased Since then, several more reports have linked viscosity
changes to disease. But, intriguing as these are, we still await proof that changes in viscosity precede the clinical manifestations and are the prime factor. Usually a raised viscosity is secondary to some other lesion. In sickle-cell disease, for instance, though an increase of blood viscosity precedes peripheral occlusion,2the basis of the disease is an abnormal haemoglobin. Manipulation of blood viscosity, though it may relieve some of the complications, is unlikely to be a complete solution. Furthermore, we still know little about how to change blood viscosity for optimum blood-flow. Reducing the hxmatocrit or plasma-fibrinogen is not necessarily beneficial. This week a group from Queen Square present evidence that patients with a haematocrit over 46% tend to have a low cerebral blood-flow; and they attribute the depression of blood-flow to the increased peripheral resistance which results from raised viscosity. By reducing the haematocrit from 49.3% to 42-6% they raised the mean cerebral blood-flow by half-from 41.1 to 62.1ml/100 g/min. In the succeeding article, a St. Mary’s group likewise link hyperviscosity with haematocrit, in patients with angina. The relation between haematocrit and blood-flow is probably more complex than these workers suggest; viscosity may be only part of the mechanism. Cardiac output is determined approximately by arterial pressure divided by peripheral resistance. The main pressure drop occurs across the vessels of the microcirculation. Peripheral resistance is influenced by the geometry and size of these vessels and by blood viscosity. Both groups reporting this week assume that the change of peripheral blood-flow results directly from an effect of haematocrit on blood viscosity; but this may be wrong. Firstly, there is evidence that the haematocrit is lower in arterioles and capillaries than in large arteries and veins. There is no evidence that an increase in the arterial-venous haema1. Lancet, 1975, i, 113. Chien, S., Usami, S., Bertles, J. F. J. clin. Invest. 1970, 49, 623.
2
tocrit produces a corresponding increase in the haematocrit of the microcirculation. Even if it did, this would not greatly alter the blood viscosity in this region of the circulation. The influence of hxmatocrit on blood viscosity falls steadily with decreasing vessel bore,until in vessels of 4 to 15 (im bore it has no effect.3 Similarly the influence of shear-rate is unlikely to be important. Irrespective of conflicting views as to whether the shear-rate in capillaries is high or low, the effect of shear-rate decreases with hsematocrit, and hsematocrit, as we have said, is reduced. The physical nature of flow in small vessels is not the same as that in large arteries and veins. The relation of flow-rate to driving-pressure in small vessels is linear, irrespective of the haematocrit. 3,4 The suggestion that a reduction of haematocrit gives rise to an increase in cardiac output,S,7 owing to a reduction of blood viscosity, also requires more convincing evidence than we have yet seen. The increased blood-flow is more likely to be due to lowered oxygen transport, associated with the lowering of the haemoglobin content ; and to assess this accurately we need to know not only the haematocrit but also the shape of the ozygen-dissociation curve, the difference of arterial to venous Po2, and the pH changes involved. The clinical improvement reported by the Queen Square group may result, as they suggest, simply from increased blood-flow, but there are other possible explanations. A factor not so far considered is the improvement in temperature which accompanies increased flow. Perfusion in turn improves as vessels dilate and the blood viscosity falls (particularly at low shear-rates). The influence of temperature on blood viscosity has not been system-
atically investigated as a means of improving tissue perfusion and reducing venous thrombosis. There is good evidence that blood viscosity in the microcirculation is determined predominantly by the plasma viscosity and erythrocyte flexibility. In this respect the paper of BARNES and others8 suggesting an association of erythrocyte flexibility with the degree of diabetic microangiopathy is of particular interest. One difficulty in accepting these data is their earlier work9 with the same filtration technique, showing that erythrocyte flexibility does not contribute to whole-blood viscosity at any shear-rate. What factor, then, accounts for the variation of whole-blood viscosity observed in normal subjects and patients at high shear-rates? The other difficulty is that a similar range of variation of 3. Jay, A. W. L., Rowlands, S., Skibo, L. Can. J. Physiol. Pharmac. 1972, 50, 1007. 4. Gregersen, M. I., Bryant, C. A., Hammerle, W. E., Usami, S., Chien, S.
Science, 1967, 157, 825. 5. Dormandy, J. A. Br. med. J. 1971, iv, 716. 6. Prothero, J., Burton, A. C. Biophys. J. 1962, 2, 199. 7. Segal, N., Bishop, J. M. J. clin. Invest. 1966, 45, 1555. 8. Barnes, A. J., Locke, P., Scudder, P. R., Dormandy, T. L.,
Dormandy, J. A., Slack, J. Lancet, 1977, ii, 789. 9. Reid, H. L., Dormandy, J. A., Barnes, A. J., Lock, P. J., Dormandy, T. L. ibid. 1976, i, 666.
pharmacologists. The past decade, however, has seen an awakening of interest in the condition and an improvement in both the quantity and the quality of research. Many important and interesting, but still unsolved, problems connected with the disease have emerged, and its economic and financial consequences are only now beginning to be understood. Moreover, the emergence of penicillin-resistant, -lactamase-producing gonococci has called into question world-wide antibiotic policies, especially the ease with which antibiotics can be obtained without prescription in many countries. This excellent book contains most of what is known of the subject. It is invaluable for all those who treat patients with sexually transmitted diseases, and should be read by postgraduate students in this subject ; it is also an excellent reference book for epidemiologists, physicians in other branches of medicine, and microbiologists. The text is precise, clearly written, and lightened from time to time by Dr Morton’s attractive sense of humour; besides being easy to read it is illustrated by helpful photographs and tables. Each chapter ends with a full list of references. The best sections of the book are those on the history of gonorrhoea, gonococcal septicaemia, and the size and nature of the problem gonorrhoea poses. In his concluding chapter on the control of gonorrhoea, Morton is pessimistic; he believes that modem social, behavioural, and medical trends will result in a high prevalence of the disease for the rest of this century at least. Politicians, health administrators, and all those who plan and
Reviews of Books
Abortion MALCOLM POTTS, PETER DIGGORV, and JOHN PEEL. London and New York. Cambridge University Press. 1977. Pp. 575. 17.50
(paperback 3.95). THIS is a valuable and extensive review of abortion throughout the world and over the course of time. It has a British bias because of the origin of the authors; the sociological evidence is interesting and well analysed; and the book has a uniformity of style and approach. Those who have followed the abortion debate will know from the names of the authors the sort of conclusions which will be reached. They have convinced themselves of the necessity for abortion, judiciously used with contraception, and they wish to convince others of the validity of their case, stated in elaborate detail which is difficult to find in summary elsewhere. Their case is convincing, though that will not be conceded by everyone. They try hard to do justice to their opponents, but Roman Catholic theologians and some doctors are criticised severely, and sometimes with conscious cleverness. This will not rout the dissenters who, nevertheless, should listen to this generally well argued exegesis. Abortion has been used by all societies. It has been, and is a problem which will not go away. Whether society, through its legislators, lawyers, doctors, and moralists, welcomes termination of pregnancy or rejects it is of small consequence. Many women and their helpers have made their decisions known in action, and the evidence is clearly documented here that abortion will probably remain a feature of fertility control for some time to come. The reader can like it or lump it, but if at the moment he can only lump it because of what, to him, are important ethical considerations, then this book may help him to define those more closely and compare them with those of others. There is fodder for all sides of the argument, but interpretation depends on many inexplicit factors not necessarily amenable to reason. Sir Thomas Browne might be allowed the last word on what it is all about. "As Reason is a Rebel unto Faith, so Passion unto Reason: as the propositions of Faith seem absurd unto Reason, so the Theorems of Reason unto Passion, and both unto Reason". Exactly. So the debate must continue, but with the hope that it will be conducted at the high level of tolerance shown in this book. The authors’ bouts of passionate polemic, comparatively rare, might be overlooked in the same spirit.
Gonorrhcea R. S. MORTON, F.R.C.P.E., The Royal Infirmary, Sheffield. London and Philadelphia: Saunders. 1977. Pp 292. [,10.
has risen
the past twenty than 250 000 000 mfections with gonorrhoea a year throughout the world. Control measures have clearly failed. The disease has, until lately, THE incidence of
gonorrhoea
years and it is estimated that there
been neglected by
over
are more
physicians, microbiologists, epidemiologists,
51 Nielsen, K.H., White, R.G.Nature, 1974, 250, 234. 52 Pepys, M. B. ibid. 1972, 237, 157 53 Pepys, M.B J. exp.Med. 1974, 140, 126. 54 Pepys, M.B. Transplantn Rev. 1976, 32, 93. 55 Pepys, M. B., Brighton, W. D., Hewitt, B. E., Bryant, D. E., Pepys, J. Clin. exp.Immun.1977, 27, 397. 56 Crane, C. G., Rowley, M. J., Warburton, M. F., Mackay, I. R. Clin. Sci. 1972, 43, 869. 57 Papamichail, M., Gutierrez, C., Embling, P., Johnson, P., Holborow, E. J., Pepys, M.B.Scand. J.Immun. 1975, 4, 343. 58 Terry, R. J., Freeman, J., Hudson, K. M., Longstaffe, J. A. Trans. R. Soc. trop Med.Hyg. 1973, 67, 263. 59 Diamantstein, T., Keppler, W., Blitstein-Willinger, E., Ben-Effraim, S. Immunology, 1976, 30, 401.
health-care services should heed his words and ensure that modern facilities for diagnosis and treatment are available, including contact tracing and improved health education.
Medical Selection of Life Risks R. D. C.
1977.
BRACKENRIDGE,
F.R.C.P.E.
London: Undershaft Press.
Pp. 765.[15.
WHILST most doctors frequently fill up forms on their patients for the benefit of life-insurance schemes, few have much idea of what happens next-or how the risk is calculated. The insurance companies turn in healthy profits and few become bankrupt, so their methods must be efficient from a business point of view. Dr Brackenridge’s survey of the medical side of life insurance is an up-to-date and well-written account of how risk is calculated. Since his first review 15 years ago the results of many long-term epidemiological studies concerned with mortality risk have made a reference manual for the insurance medical officer a necessity-and this book is it. However, it is also relevant to other disciplines. The first part of the book deals with the principles of selection and the rating systems used by insurance medical officers on "substandard" lives. The second part provides a detailed analysis of the prognosis of a wide spectrum of treated and untreated disease-each section ending with practical advice to the examining doctor as to how to assess the risk. Despite the fact that there is a measurable difference between the mortality of "insured lives" (upon which most of the vital statistics presented are based) and that of the general population, the book provides a useful reference for people concerned with prospective surveys of mortality and morbidity and the review of world literature appears comprehensive. For this reason too, clinicians will find useful tables of prognostication to compare with their own experience and to help in advising patients and their relatives of the likely outcome of particular diagnosis and operations. The statistics apply to groups of patients, and the art is knowing how to apply them to the individual case. To help the clinician the author includes between the tables and the risk-rating paragraphs, good clinical sections on each disease, highlighting the prognostic features. His philosophy with regard to minor ailments and their relationship to the whole patient is stimulating and his attitude towards stress-related illness enlightened. The book is well presented; and the tables, with one or two exceptions, are easy to understand, and there is a comprehensive index.
960 Haemostasia British Medical Bulletin: vol. XXXIII, no. 3. Edited by DUNCAN THOMAS. London: British Council. 1977. Pp. 292. 4.50 ([,5 over-
seas). THE British Medical Bulletin usually provides nourishing fare, and the September, 1977, issue is no exception. Here, the normal haemostatic mechanism and some of its major disorders have been reviewed. The number of reviews on haemostasis and thrombosis has swelled from a trickle to a flood in recent years. This collection of essays on haemostasis is too brief for the specialist, but it does provide useful information for non-specialist biochemists and clinicians with an interest in haemostasis and thrombosis. The first four chapters, which deal with the platelet and its abnormalities, start with a reminder by J. F. Mustard and M. A. Packham of the extent to which major research in platelet biochemistry is carried out overseas. This is followed by a section on coagulation where Dr Esnouf has had the herculean task of reviewing the biochemistry of coagulation in one chapter; but he has had to omit large quantities of important information (for example, the nature of the different types of thrombin). Professor Bloom has given a good account of the different theories on the nature of factor vm, whilst the fibrinolytic mechanisms have been well covered by Dr Kernoff and Professor McNicol. Dr Rizza is on firm ground whilst writing about the clinical management of haemophilia although, clinicians will feel the need for further discussion on the use of prothrombin concentrates for the treatment of factor-viii inhibitors. Useful, clinically oriented chapters are provided by P. T. Flute, G. 1. C. Ingram, S. J. Urbaniak, and J. D. Cash, whilst A. A. Sharp emphasises the difficulty of evaluating treatment in disseminated intravascular coagulation. The final chapter by T. W. Meade and W. R. S. North is an important attempt to apply epidemiological techniques to haemostatic variables. The chief conclusion would seem to be that factors affecting haemostasis are indeed variable, thus confirming observations that levels of factors vin and v and results of tests of fibrinolysis and platelet function do fluctuate within an individual. It is probable that more accurate detection of individuals at risk for thrombotic diseases may require studies of activated clotting factors, or components derived from platelets, as well as turnover studies.
wards an extreme mechanistic interpretation of behaviour, this is an excellent book, superbly produced and illustrated, and packed with thought-provoking facts. It will be invaluable for those interested in the electrical and molecular basis of neuro-
physiology. Current Respiratory Care Edited by KENNETH F. MACDONNELL and MAURICE S. SEGAL. Boston: Little, Brown, Beckenham: Quest. 1977. Pp. 489.
$14.50,[9.60. THIS book consists of specialist essays on selected aspects of respiratory medicine. The aim is to inform physicians, anasthetists, physiotherapists, and nurses of each others’ specialised activities in the care of respiratory patients. Theoretically, this is excellent but in practice some of the chapters demonstrate that the gulf between members of the respiratory team is uncomfortably wide--can the average nurse or physician be expected to understand the intricate workings of a mechanical ventilator, for example? The essays are based on a postgraduate course on respiratory therapy held annually at Tufts University. The style varies widely between the various contributions, and so does the intellectual demand made by them. Some of the chapters are very valuable, and indeed unique among textbooks. One example is the contribution on sputum, with the problems it brings to respiratory therapists. Other contributions are very sketchy, and it seems pointless to include them when so many others cover the same subject in more detail and more clearly (examples include the immunological contribution and some of the purely descriptive clinical essays). The value of the book lies mainly in the detailed descriptions of many techniques involved in respiratory care, particularly those associated with mechanical ventilation. Unfortunately, several commonly required techniques are not fully covered; bronchoscopy is dealt with rather summarily, with no mention of the segmental anatomy, and techniques such as pleural aspiration and biopsy do not receive attention. Nevertheless, the book contains many items of great interest and can be recommended, particularly to those concerned with the intensive care of respiratory patients. Advanced Medicine 13 1977.
An Introduction to Behavioral Neurobiology. ERIC R. KANDEL. San Francisco: Freeman. 1976. Pp. 727.$45.
THE first
chapter of this book claims that "an effective biology of behavior can best be achieved by concentrating on a specific organism". The organism selected is Aplysia californica, a marine mollusc in which the approach central
to
cellular
nervous
system consists of
by G. M. BESSER. Tunbridge Wells: Pp. 497. £ 8.50.
Edited
Cellular Basis of Behavior
no more
ganglia containing relatively large
nerve
than cells.
a
series of
Compared
with vertebrate nerve cells, the mollusc neurons are simple structures; in many cases their specific interconnections can be readily determined. Moreover, cells can often be individually identified, making it possible to study the same neuron in individual animals under different conditions. This and other features make Aplysia especially suitable for the study of inter-ceii connections and for relating types of neuronal circuits with types of activity. A large part of the book is devoted to detailed descriptions of Dr Kandel’s own research; he has shown, for example, how motor and sensory circuits interact to control feeding, locomotion, and defensive reflexes. But are these basic activities "behaviour"? Kandel is in no doubt: "... the contraction of muscles, changes in visceral tone, and secretions of the glands are the basic elements of observable behavior. They are the only aspects of mental processes that can be studied directly." Others may feel that the complexity of behaviour in man and higher animals, while founded on the basic elements, ultimately requires explanation in different terms even at the level of neurophysiology. But apart from this bias to-
Pitman Medical.
THIS book is the latest in a series published by the Royal College of Physicians. The editor’s aim is to review, in an easily assimilable fashion, areas in medicine of general interest to clinicians in which there has been recent growth. Professor Besser has succeeded and this book is a pleasure to read. Neur-
ology, oncology, endocrinology, genital medicine, cardiorespiratory medicine, and gastroenterology are well covered. There also sections on new methods and treatments. This book must for doctors preparing for higher examinations, while experienced doctors who read it will find themselves repaid, The high standard of medical writing should encourage other authors to pay more attention to presentation and style. are
is
a
New Editions Current Therapy 1977-Edited by Howard F. Conn. and London: Saunders. 1977. Pp. 986.$24.50; k20.25.
Philadelplua
A Short Textbook of Surgery--4th ed. By Selwyn Taylor and Leonard Cotton. London: Hodder & Stoughton. 1977. Pp. 634. ’.4
(paperback 3.95). The Shorter Bergey’s Manual of Determinative Bacceriolog.B8!h ed. Edited by John G. Holt. Baltimore: Williams & Wilkins. London Quest. 1977. Pp. 356.$15.95; 10.55. Fundamentals of Obstetrics & Gynaecology: vol. I, Obstetrics-B Derek Llewellyn-Jones. London: Faber & Faber. 1977. Pp. 471. 1, kQ
(hardback 12).
961
THE.LANCET
Hyperviscosity
in Disease
Two years ago we reviewed the factors which influence blood viscosity in health and diseased Since then, several more reports have linked viscosity
changes to disease. But, intriguing as these are, we still await proof that changes in viscosity precede the clinical manifestations and are the prime factor. Usually a raised viscosity is secondary to some other lesion. In sickle-cell disease, for instance, though an increase of blood viscosity precedes peripheral occlusion,2the basis of the disease is an abnormal haemoglobin. Manipulation of blood viscosity, though it may relieve some of the complications, is unlikely to be a complete solution. Furthermore, we still know little about how to change blood viscosity for optimum blood-flow. Reducing the hxmatocrit or plasma-fibrinogen is not necessarily beneficial. This week a group from Queen Square present evidence that patients with a haematocrit over 46% tend to have a low cerebral blood-flow; and they attribute the depression of blood-flow to the increased peripheral resistance which results from raised viscosity. By reducing the haematocrit from 49.3% to 42-6% they raised the mean cerebral blood-flow by half-from 41.1 to 62.1ml/100 g/min. In the succeeding article, a St. Mary’s group likewise link hyperviscosity with haematocrit, in patients with angina. The relation between haematocrit and blood-flow is probably more complex than these workers suggest; viscosity may be only part of the mechanism. Cardiac output is determined approximately by arterial pressure divided by peripheral resistance. The main pressure drop occurs across the vessels of the microcirculation. Peripheral resistance is influenced by the geometry and size of these vessels and by blood viscosity. Both groups reporting this week assume that the change of peripheral blood-flow results directly from an effect of haematocrit on blood viscosity; but this may be wrong. Firstly, there is evidence that the haematocrit is lower in arterioles and capillaries than in large arteries and veins. There is no evidence that an increase in the arterial-venous haema1. Lancet, 1975, i, 113. Chien, S., Usami, S., Bertles, J. F. J. clin. Invest. 1970, 49, 623.
2
tocrit produces a corresponding increase in the haematocrit of the microcirculation. Even if it did, this would not greatly alter the blood viscosity in this region of the circulation. The influence of hxmatocrit on blood viscosity falls steadily with decreasing vessel bore,until in vessels of 4 to 15 (im bore it has no effect.3 Similarly the influence of shear-rate is unlikely to be important. Irrespective of conflicting views as to whether the shear-rate in capillaries is high or low, the effect of shear-rate decreases with hsematocrit, and hsematocrit, as we have said, is reduced. The physical nature of flow in small vessels is not the same as that in large arteries and veins. The relation of flow-rate to driving-pressure in small vessels is linear, irrespective of the haematocrit. 3,4 The suggestion that a reduction of haematocrit gives rise to an increase in cardiac output,S,7 owing to a reduction of blood viscosity, also requires more convincing evidence than we have yet seen. The increased blood-flow is more likely to be due to lowered oxygen transport, associated with the lowering of the haemoglobin content ; and to assess this accurately we need to know not only the haematocrit but also the shape of the ozygen-dissociation curve, the difference of arterial to venous Po2, and the pH changes involved. The clinical improvement reported by the Queen Square group may result, as they suggest, simply from increased blood-flow, but there are other possible explanations. A factor not so far considered is the improvement in temperature which accompanies increased flow. Perfusion in turn improves as vessels dilate and the blood viscosity falls (particularly at low shear-rates). The influence of temperature on blood viscosity has not been system-
atically investigated as a means of improving tissue perfusion and reducing venous thrombosis. There is good evidence that blood viscosity in the microcirculation is determined predominantly by the plasma viscosity and erythrocyte flexibility. In this respect the paper of BARNES and others8 suggesting an association of erythrocyte flexibility with the degree of diabetic microangiopathy is of particular interest. One difficulty in accepting these data is their earlier work9 with the same filtration technique, showing that erythrocyte flexibility does not contribute to whole-blood viscosity at any shear-rate. What factor, then, accounts for the variation of whole-blood viscosity observed in normal subjects and patients at high shear-rates? The other difficulty is that a similar range of variation of 3. Jay, A. W. L., Rowlands, S., Skibo, L. Can. J. Physiol. Pharmac. 1972, 50, 1007. 4. Gregersen, M. I., Bryant, C. A., Hammerle, W. E., Usami, S., Chien, S.
Science, 1967, 157, 825. 5. Dormandy, J. A. Br. med. J. 1971, iv, 716. 6. Prothero, J., Burton, A. C. Biophys. J. 1962, 2, 199. 7. Segal, N., Bishop, J. M. J. clin. Invest. 1966, 45, 1555. 8. Barnes, A. J., Locke, P., Scudder, P. R., Dormandy, T. L.,
Dormandy, J. A., Slack, J. Lancet, 1977, ii, 789. 9. Reid, H. L., Dormandy, J. A., Barnes, A. J., Lock, P. J., Dormandy, T. L. ibid. 1976, i, 666.
