ABSTRACTS OF MEMBERS PAPERS 401 PART I: ABSTRACTS OF MEMBERS' PROFFERED PAPERS ENHANCEMENT OF CHEMICALLY- Pregnant rats were injected with ethyl- INDUCED NEOPLASIA BY PROXI- nitrosourea to induce cerebral gliomas in a MAL ENTERECTOMY. R. C. N. WIL- high proportion of the offspring. With a dose LIAMSON, F. L. R. BAUER and R. A. MALT, of 40-50 mg/kg body weight the average United Bristol Hospitals and MlVassachusetts latent period for these brain tumours is 246 General Hospital, Boston, U.S.A. (Introduced days. Cultures have been prepared at by M. 0. Symes). different times after transplacental exposure Azoxymethane-induced tumours in the but before a tumour is visible. It has been rat, morphologically indistinguishable from reported previously (Roscoe and Claisse those arising in man, affect the duodenum, (1976) Nature, Lond., 262, 314) that there is jejunum and colon, but usually spare the a marked difference in the behaviour of ileum (Ward, J. M. (1975) Vet. Pathol., 12, cultures prepared 138-145 days p.i. and 2 165). Proximal small-bowel resection (PSBR) days p.i. These experiments have been causes prompt ileal hyperplasia, with a lesser extended and are reported here. Cultures response in the colon. To test the possible prepared 111-112 days p.i. were similar to adjuvant effect of postresectional hyper- those derived 138-145 days p.i. They con- plasia on intestinal carcinogenesis, rats tained cells like those found in tumour (n= 76) were submitted to 5000 PSBR 10 cultures which can predominate in culture days after the last of 16 weekly injections of and are tumourigenic. Similar cells observed azoxymethane (10 mg/kg s.c.) or vehicle. in cultures prepared 90-91 days p.i. appear Controls were unoperated. Nucleic acid to be lost on sub-culturing. These cells were contents of upper ileal mucosa in rats receiv- not seen when cultures were initiated at still ing vehicle alone showed increments of 76% earlier times (60, 34-35, 5, 3, 2 days p.i.). (RNA) and 680, (DNA) 3 nionths after However it has been shown that cultures PSBR (P < 0-001). The number and distri- prepared 2 days p.i. yield cells which are bution of intestinal tumours were noted in tumourigenic on prolonged culturing. These rats sacrificed at 30 weeks, or dying of cancer results provide a framework for further in the preceding 4 weeks. Intestinal tumours analysis of the latent period and more detailed occurred in all but 1 of the rats receiving studies are in progress. No. tumours par rat (after azoxymothane) Duodenojejunum Ileum Colon Ear canal Control 18 1 3 0.1 1-6 0-8 PSBR 16 0 8 nil 2 * 9 1 2 NS NS P<0-02 NS azoxymethane, but in none of those injected FIBRINOLYTIC ACTIVITY ASSOCI- with vehicle. Proximal enterectomy raised ATED WITH RAT BRAIN CELLS the incidence of colonic tumours but failed to EXPOSED TRANSPLACENTALLY TO induce ileal carcinogenesis, despite promoting THE CARCINOGEN ETHYLNITRO- marked mucosal hyperplasia. We conclude SOUREA. T. A. HINCE and J. P. ROSCOE, that postresectional hyperplasia cannot over- Department of Cell Pathology, School of Patho- come the relative insusceptibility of the ileum logy, Middlesex Hospital Medical School. to neoplasia, but that it enhances the induc- tion of tumours in colon previously exposed An increased fibrinolytic activity of to chemical carcinogens. tumour and transformed cells, as a result of increased amounts of plasminogen activator, AN INVESTIGATION OF ETHYL- has been proposed as another marker for NITROSOUREA-INDUCED CARCINO- transformed cells (Jones et al. (1976) Cancer GENESIS IN THE RAT BRAIN BY AN Res., 36, 2863). In this study we have investi- IN VIVO-IN VITRO METHOD. J. P. gated the fibrinolytic activity of cell lines RoSCOE and P. J. CLAISSE, Department of derived from cerebral gliomas of the rat brain Cell Pathology, School of Pathology, Middlesex and cultures derived from the brains of rats Hospital Medical School. after their transplacental exposure to the 402 B.A.C.R. 18TH ANNUAL GENERAL MEETING carcinogen ethylnitrosourea (ENU) using inflammatory response with consequenit leak- an in vivo/in vitro system (Roscoe and Claisse, age of serum; the plasminogen would then be 1976, Nature, Lond., 262, 314). Using a fibrin- locally activated by the tumour cells which overlay method (Jones et al., 1975, Cell, 5, *Would then divide at a faster rate. 323) we have demonstrated that cell lines derived from a cerebral glioma and from rat brains 111-112 days after their exposure to the carcinogen show a very high level of fibrinolytic activity. In contrast, control cells CONTROL OF HAEMOPOIETIC and cultures derived from the brains of STEM-CELL POPULATIONS. E. G. animals exposed to buffer alone show low WRIGHT, Paterson Laboratories, Christie Hos- levels of activity. A detailed study of the pital and Holt Radium Institute, Manchester. relationship between fibrinolytic activity, (Introduced by R. Schofield). measured as the percentage of total colonies giving lysis, and cell colony size indicated Haemopoietic cells are derived from com- that there was a marked difference between mon pluripotential spleen-colony-forming transformed and control cells. Transformed stem cells (CFU-S). The majority of these cells showed a rapid rise in fibrinolytic stem cells, in the normal steady state, are activity with increasing colony size and not proliferating, but can be stimulated into reached a plateau level >70%0 at colony cell cycle by a decrease in their population sizes of below 70 cells/colony; wihereas con- size. The nature of CFU-S proliferation con- trol cells showed a linear increase with trol is not known. There is, however, evidence colony size and much reduced levels of that it is "local" rather than humoral. The activity: <30%0 at larger colony sizes, presence of proliferating and non-proliferat- >130 cells-colony. Thus in this system an ing stem cells in, respectively, the bone mar- increased amount of fibrinolytic activity is row and spleens of phenylhydrazine (PHZ)- associated with malignant transformation. treated mice (Rencrieca et al. (1970) Blood, 36, 764) has afforded the opportunity to investigate the presence and role of local factors responsible for the control of CFU-S SV40-3T3 CELL PLASMINOGEN ACTI- proliferation. This has been done by measur- VATOR-MEDIATED INITIATION OF ing the proliferative activity of femoral and MITOSIS IN QUIESCENT 3T3 CELLS. splenic CFU-S resulting from the addition of P. WHUR, M. GORDON, D. C. WILLIAMS, C. radiation-killed splenic or bone-marrow cell URQUHART and E. WRIGHT, Marie Curie populations. When bone-marrow cells from Foundation, Oxted, Surrey and Imperial PHZ-treated mice are incubated with irradi- College, London and Royal Free Hospital, ated spleen cells taken from the same mice, Medical School, Londont. there is a marked fall in the proportion of femoral CFU-S in DNA synthesis. In the The number of dividing cells ill a popula- converse experiments, rapid triggering of tion of quiescent 3T3 cells in low serum splenic CFU-S is achieved. Changes in increases, significantly in the presence of CFU-S proliferation have also been demon- SV40-3T3 cells and added plasminogen. This strated in other situations, where cell popula- effect is attributable to plasminogen activa- tions containing proliferating and non- tion (Whur et al. (1976) Nature, Lond., 260, proliferating CFU-S are mixed. It is not, 709). The effect of plasminogen activation on therefore, a phenomenon specifically related mitosis decreases as serum stimulation to the PHZ-treated mouse. The effects on becomes optimal, suggesting that the former the proliferative activity of CFU-S resulting may potentiate the latter. Scanning electron from the incubation of haemopoietic cells micrographs show that plasminogen activa- with irradiated cell populations suggest that tion causes fissures to open between previously some part or parts of these populations con- confluent 3T3 cells; thus the diffusion boun- tain material capable of altering the rate of dary layer may become disrupted, leading to stem-cell proliferation. It seems probable a reinitiation of mitosis by serum growth that these findings represent some aspect factors. This mechanism may also operate of the local physiological CFU-S proliferation- in vivo. Tumour cells would initiate a local control process. ABSTRACTS OF MEMBERS PAPERS 40.3 THE SPECIFIC STAINING OF staining. Normal monocytes showed weak, SUGARS IN THE HISTOCHEMICAL uniform staining for sialic acid and little ANALYSIS OF BONE MARROW staining for other sugars. Malignant mono- AND THE MYELOID LEUKAEMIAS. cytes stained weakly and irregularly for R. W. STODDART, W. JACOBSON and R. D. surface sialic acid and showed very little stain COLLINS, Strangeways Research Laboratory, for galactose or mannose; some appeared to Cambridge. and Department of Pathology, show caps. In acute lymphoblastic (human Vanderbilt University, Nashville, Tennessee, and murine) and chronic lymphocytic leuk- U.S.A. aemias the malignant cells showed much less staining for sialic acid than their normal coun- In many glycoproteins of cellular surfaces, terparts, both at the plasmalemma and nu- mannosyl residues lie in the "cores" of the clear membranes. Staining for mannose was oligosaccharides, while sialic acid is always at unaltered. There were no differences between the non-reducing (exterior) terminals. Galac- B and T lymphocytes. The malignant cells of tosyl groups are usually either terminal or nodular and thymic lymphomas gave a sub-terminal to sialic acid. Fluorescent- similar result. In all types of Hodgkin's labelled concanavalin A (FL-ConA) can be disease, the neoplastic lymphocytes were used to stain for a-mannosyl (or a-glucosyl) characterized as showing a reduction in groups; the similar derivatives of Ricinus sialic acid and in sub-terminal galactosyl communis haemagglutin (FL-RCA) and of groups; Reed-Sternberg cells were weakly aprotinin (FLA) stain for /-galactosyl groups stained for all sugars.