The finding of differences i n the activity of the enzyme 5'-nucleotidase between the anterior and posterior portions of the molecular layer of the cerebellum of the mouse was reported recently from this laboratory (Scott, '63). In addition, sections cut in the horizontal plane showed the enzyme to be distributed in certain bands running in an antero-posterior direction. In view of the reported absence of different cytoarchitectonic regions in the cerebellum (e.g. Kappers et al., '36; Jansen and Brodal, '54), it was decided to pursue the matter further in the hope that some correlation with the known data 011 functional localization would emerge. MATERIAL AND METHODSThe mice ( G strain) were killed by chloroform anesthesia and the brains were immediately dissected out. These were then frozen onto the chuck of a Pearse-Slee cold microtome by solid CO,. Sections were cut 10 thick at -17°C in sagittal, horizontal or vertical planes. In two mice sections were cut semiserially, every tenth section being used for demonstrating the enzyme. The finished serial sections were then photographed and enlarged to a 20 X magnification. The photographs were mounted on card to a final thickness 01 2 mm. The images of the sections were then cut out and mounted one upon the other in order to obtain a better understanding of the three-dimensional distribution of the enzyme.The enzyme itself was demonstrated by the lead sulphide technique described by Naidoo ('62) after the air-dried and mounted sections had been fixed for 20 minutes in formol/calciurn ( 4 % v/v and 1% w/v respectively) at 4°C. RESULTSIn sagittal sections the cerebellum of the mouse can be seen to be in the shape of a somewhat distorted triangle (fig.

The distribution of the enzyme 5'-nucleotidase in the brain of the mouse is described in detail. The structures showing the greatest amount of activity are the corpus striatum, the substantia gelatinosa, the lateral longitudinal stria, the nodulus of the cerebellum and parts of the retina. In the cerebellum in particular, and to some extent in the hippocampus, the distribution is such as to suggest that the enzyme may be actively involved not only in simple biochemical processes but possibly also in some neurophysiological function.

5'-Nucleotidase in the brain of the mouse was examined histochemically. By means of various fixatives, substrate omission, heat effects, pH variation, ionic activators and inhibitors, an antigenic inhibitor (cobra venom antiserum) and substrate specificity, it was shown that the histochemical technique is specific for 5'-nucleotidase, and that it did not depend upon non-specific phosphatases. The enzyme was also show to hydrolyze seven different mononucleotides, but not a dinucleotide, two trinucleotides nor ribose 5-phosphate. Evidence is presented that the hydrolysis of the various mononucleotide substrates may be due either to separate 5'-nucleotidases or to isoenzymes.

5'-Nucleotidase (5'-ribonucleotide phosphohydrolase, EC 3.1.3.5) has been shown to have a wide specificity for nucleoside 5'-monophosphates (Heppel & Hilmoe, 1951; Levin & Bodansky, 1966). Attempts have been made to resolve this enzyme into active components by electrophoresis in starch gel (Kowlessar,

Two hundred and forty-seven strains of micro-organisms were isolated from the urinary tract of 121 patients with neurological complaints leading to paraplegia. The commonest infecting organism was E. coli and the commonest type of Proteus was P. mirabilis. Infections with more than one type of organism were prcsent in 37% of urine specimens, and in such cases the incidence of E. coli was lower and that of Strep. faecalis higher than the incidences in infections with only one type of organism.No evidence was found which might suggest that the various bacterial species encountered showed either an undue degree of synergism or of mutual antagonism.Coliforms were the commonest primary pathogens, but Strep. faecalis and Proteus species occurred with the same frequency as the coliforms when they were considered as secondary invaders.The variance between the incidence-of various species as reported by different workers is considered to be due to the different illne33es and conditions which predispose to urinary tract infection. It appears that infections in the urinary tract by more than one type of organism at a time occur more frequently in those patients with the more chronic predisposing causes.(Some disparity in findings may also reisult from the di-ffering taxonomic methods employed by ditferent workers, but this is probably insufficiently important to account for the largest differences.)In the course of routine examination of the urines of paraplegic patients in this hospital the high incidence of infected urines containing more than one type of organism was noted. It was decided to investigate paraplegic urines with specific reference to the frequency of various bacterial species, the possibility of the bacteria in multiple infections exerting mutual antagonism or synergism, and the relative importance of organisms as primary pathogens and as secondary invaders of the urinary tract. It is proposed to discuss the results against a review of the findings of certain other workers in other branches of medical and surgical practice. Material and MethodsThe number of patients with urinary tract infections investigated in one calendar year was 121. All of the patients had paraplegia in some form or another and in no case could it be shown that the infection began suddenly as, for example, in an acute pyelonephritis. Whenever possible specimens of urine were *Present address-Department of Pathology, The Hospital for Sick Children, Great Ormond Street, London, W.C.1. obtained for culture from women by catheterization and from men by catheterization or by the "midstream" technique, but many patients at one time or another were on some form of bladder drainage, and this was then used as the means of obtaining the specimen. The organisms were isolated primarily on McConkey's bile salt lactose agar and blood agar.