EQUIPMENT FOR LEUKEMIA RESEARCH INSTALLED

Press, Volume CIII, Issue 30543, 11 September 1964, Page 14

EQUIPMENT FOR LEUKEMIA RESEARCH INSTALLED

New equipment for leukemia research has been bought at a cost of more than £3OOO from Golden Kiwi funds for the Canterbury and Westland division of the New Zealand Cancer Society and installed in its Cytogenetics Unit laboratory in St. Asaph street, where it will be used in a new research programme planned by the honorary director of the unit (Dr. F. W. Gunz). A British research worker in leukemia, Dr. A. J. Hale, of the St. Thomas’s Hospital Medical School, London, has come to Christchurch at the request of the society to help to set up the equipment and train and advise the staff who will use it. The equipment is an integrating microdenistometer, which gives the weights of minute quantities of material by measuring the extent to which they interrupt a light beam. In the research to be carried out in the Cytogenetics Unit, the object will be to measure the amounts of D.N.A. (deoxyribose nucleic acid) in individual white blood cells. D.N.A. is the material forming the chromosomes of living cells—the threads within the cell nucleus which largely direct

the functioning of the cell. The weight of material involved in each cell is about a picogram (a millionmillionth of a gram). To make D.N.A. absorb the beam of the microdensitometer, a special strain known as Feulgen strain, is used which is specific to D.N.A. The microdensitometer will be used in conjunction with a radioactive isotope technique to estimate the rate of manufacture of D.N.A. in normal and leukemic cells from its constituent nucleotides. In leukemias and certain other cancers, the amount of D.N.A. in the cell changes because the chromosome pattern changes; but very little is known about the relationship between the change in the chromosome pattern and the change in the mechanism of D.N.A. synthesis (production). This matter is very important because the basic error in cancer cells is that they keep on dividing and I cease carrying out most of their normal activities; and for cell-division, D.N.A. synthesis is necessary. The nucleotide used in the radioactive tracer technique is thymidine, labelled with tritium (radioactive hydro-

gen) or, occasionally, carbon--14. A slide bearing a smear of cells is first clamped next to a photographic emulsion, on which the tritium disintegrations will show up as silver grains, which are counted: and then each cell is examined under the microdensitometer and its amount of D.N.A. measured. Tritium emission has a very short path length, and there is usually no difficulty in deciding in which cell a disintegration has taken place. The examination of individual cells is essential in leukemia research because there are several basic types of both leukemic and normal cells, and each type varies in its characteristics as it ages. The examination of a “population” of cells gives, therefore, only average values which may not vary significantly as between a leukemic patient and a normal person.

Dr. Hale said that radioactive labelling techniques and microdensitometer measurements had each been used in leukemia research by various laboratories, but the group at St. Thomas’s was the first to correlate the two methods. At St. Thomas’s, the main object of the

current programme in this field was to elucidate the basic mechanism of control of the synthesis of D.N.A.; Dr. Gunz’s group was more interested in chromosome abnormalities and their relation to D.N.A. synthesis. The staff members being instructed by Dr. Hale are Mr P. H. Fitzgerald, the associate director, and Miss P. O’Connor, a laboratory assist- 1 ant.