Book Reviews

Enzyme and Protein Changes in Myelin Breakdown and Multiple Sclerosis, Vol. 3, No. 4, Progress in Histochemistry and Cytochemistry. By J. F. Hallpike. Gusta Fischer Verlag, Stuttgart and Portland, Oregon, 1972. Paperbounds DM 36 (preference price for subscribers to series DM 29). 38 pp. 27 figs. In 1850 Waller published his pioneering experiments on section of the glossopharyneal and hypoglossal nerves of frog. This report ushered in a new era in neurobiology and simultaneously gave Wallenian degeneration, a potent experimental model for myelin breakdown, to neuroscientists. However, many problems still remain despite the enormous post-Wallerian advance in our knowledge of the biology and pathology of the myelin sheath. Among these problems myelin breakdown in health and in disease would rank high in any contemporary list of neurologic subjects urgently requiring elucidation. Hallpike has undertaken, in the span of this brief (37-page) monograph, to review briefly the biochemical, histochemical and pathologic literature bearing on this subject. The primary purpose of this monograph, however, is to set forth and examine the hypothesis first suggested by Adams and Tuquan in 1961 that myelin breakdown in Wallerian degeneration and certain other conditions, notably multiple sclerosis, may be associated with damage to a specific myelin protein, the myelin basic protein, brought about by the activity of neural proteases. Gutman and Holubar in 1950 first suggested that increased proteolysis may be a mechanism for early breakdown of myelin after neurotomy. Subsequently a number of workers showed that increased levels of neutral and acid (lysosomal) protease activity occur in degenerating peripheral nerve following section. Professor Adams, Dr. Hallpike and colleagues at Guy’s Hospital Medical School in London have made noteworthy histochemical, biochemical and histopathologic contributions to this area of research and it is to recent findings of this group that the present opus is largely devoted. The monograph commences with a brief review of the present status of the biochemically and histochemically defined myelin proteins and their relations with the myelin lipids. After considering the various hydrolases and other enzymes purportedly present in association with myelin, the author goes on to discuss enzyme changes in Wallenian degeneration with particular reference to neutral and acid proteases, acid phosphatase and leucine aminopeptidase. Diphthenitic neuropathy, an experimental model of peripheral nerve demyelination with axonal sparing, and multiple sclerosis plaques, the clinical counterpart of the latter in the central nervous system of man, are presented as possible examples of in vivo proteolysis. Experiments are then described which indicate an in vitro loss of basic myelin protein brought about by soluble proteases from peripheral nerve. Extracts from degenerating nerve are more effective than those from control nerve, presumably because the former contain higher protease activities. Thus, in vivo proteolysis is feasible. It is interesting to note that Hallpike and associates (Csejtey et a!., J Neunochem 19:1931, 1972) have recently found that the so-called trypsin-resistant “neurokeratin” protein, the ‘J” band, of peripheral myelin is degraded by tryptic digestion and disappears pan passu with the basic myelin proteins during Wallenian degeneration (Adams et a!., J Neurochem 19: 1043, 1972). Thus, although the ink on this monograph is hardly dry, its central hypothesis is already in need of revision! A timely reminder of the mortality of hypotheses, on rather, of the increasing tempo of new discoveries. All in all, this is a stimulating and balanced presentation of multidisciplinary research into a subject of vital interest to histochemists, neurochemists, neuropathologists and other workers concerned with the nervous system. This slender volume is warmly recommended reading. Harold Koenig Veterans Administration Research Hospital and Northwestern University Medical School