In order to make the lab-on-a-chip concept a reality, it is desirable to have an integrated component capable of pumping fluids through microchannels. We have developed novel, electrically actuated micropumps and have integrated them with microfluidic systems. These devices utilize the build-up of electrolysis gases to achieve pressure-driven pumping, only require small voltages (approximately 10 V), and have approximate dimensions of 5 cm x 3 cm x 2 cm. Furthermore, these micropumps are composed of relatively inexpensive materials, and the reversible sealability of their poly(dimethylsiloxane) body to different microfluidic arrays enables repeated uses of the same pump. Under an applied potential of 10 V, three different micropumps had average flow rates of 8-13 microL min(-1) for water being pumped through five different 2 cm-long, 5500 microm(2) cross-sectional-area channels in poly(methyl methacrylate), in approximate agreement with predicted pump rates. We have also evaluated pump operation at the lower applied potential of 8 V and observed an average flow rate of 6.1 microL min(-1) for a pump-channel system. The current micropump design is capable of sustaining pumping pressures in the range of 300 kPa. The various advantages of these micropumps make them well suited for use in lab-on-a-chip analysis techniques.

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This is the first comprehensive treatise on the disorders of muscle to appear in the English language. It will surprise many to discover what a wide variety of diseases find a reflection in some pathological change in striated muscle. The emphasis of this aspect makes this a valuable reference book for the physician as well as the neurologist, and the physiologist may well ponder the evidence supplied by disease indicating that muscle tissues have other functions apart from contractility.The authors have attempted to present a clear and systematic picture of the present state of knowledge of striated muscle and its reaction to disease, as well as those disordered processes which seem peculiar to the neuromuscular mechanism. In so doing, they have indicated not only what is known, but by their orderly approach have shown clearly the very large gaps in our knowledge.The book consists of three main sections. The first deals with the developmental, morphological and physiological aspects of muscle. This is the most difficult section to read because of the compression of such a wide range of information into two chapters. It is unfortunate that much new evidence concerning neuromuscular function has appeared while this book was in press. The introduction of intracellular microelectrodes has resulted in a great increase in our knowledge of the resting, action and end-plate potentials of muscle, and many of the older ideas can now be expressed with far greater clarity. The recent electron-microscopical results have simplified the morphological aspects of the structure of the muscle fibre and the sarcolemmal sheath. The section on the innervation of muscle is most helpful, and contains one of the best accounts of the motor end-plate region easily available.In the second section the experimental pathology and the general reaction of human muscle to disease are considered. This is a most important contribution. It illustrates clearly that only with a thorough knowledge of the reaction of muscle to a wide variety of insults, both internal and external, is one in a position to decide whether a diseased muscle is primarily at fault or secondarily involved.The final section on the pathology of muscle diseases occupies half the book and nine of the thirteen chapters. It is an excellent presentation of a most diffuse aspect of medicine. Its scope is astonishing-from the shin soreness of athletes to generalized myositis ossificans; from the bite of the latrodectus to thyrotoxic myopathy. The extensive experience of the authors in experimental pathology and the clinic has resulted in a lucid and authoritative discussion of each disease.The book is beautifully printed on art paper throughout, and no praise can be too high for the superb illustrations. Apart from the intrinsic merit of the 315

Book Reviews part of the book. Valuable suimmaries in Italian, English and German occupy the terminal twenty-four pages of text: these are followed by a bibliography of about a thousand separate publications. This excellent monograph, which forms so timely an addition to the literature of endocrinology, merits a more robust form of binding. KENDAL C. DIXON.

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