Treatment of polycythaemia vera.

Abstract

Age, per se, plays no direct part in determining rate of change of pressure in these populations even though, as is seen in Figs. 1 and 2, mean pressures are much higher in the old than in the young and even though almost all old people in these populations have high pressures. Age appears to play a part solely because the blood-pressure changes on average are positive and increase with higher pressures.'he relation between change of pressure and mean pressure also appears to be a graded phenomenon-the higher the pressure the greater the rate of increase-and seems partially to reconcile the conflicting views on the nature of unexplained hypertension.If this relation were found to be causal it could explain the observations that some individuals and some races show no apparent increase in pressure with age. For example, the populations in Oceania studied by Maddocks (1961) and Lovell (1963), where old people have the same pressures as young adults, have mean pressures below the levels at which our data suggest that a self-perpetuating mechanism could be implicated. But our analysis has shown only an association between change of pressure and mean pressure, not a causal relationship. It is possible that minor but sustained increases of pressure, due to a variety of environmental and genetic influences, could lead to changes in function and structure which perpetuate a vicious circle, but some other factor acting in a similar fashion may underlie the relationship found.A controlled therapeutic trial might show whether the pressure attained determines the subsequent increments in pressure; if, for example, it could be shown that after a reduction in pressure effected by hypotensive drugs the subsequent changes in pressure of previously hypertensive subjects revert to those occurring spontaneously in subjects with lower pressures, this would be strong evidence for a causal relationship. SummaryData obtained from the longitudinal surveys of arterial blood pressure in two general population samples have been used to examine the relation between change of blood pressure, the mean pressure attained, and age.It has been shown, by multiple regression analysis of change of pressure on mean pressure and age, that in these populations changes in pressure during intervals of 10 and 8O years are highly significantly related to mean pressures, but only indirectly related to age. This implies that ageing plays no direct part in determining the rate of change of pressure; age appears to play a part solely because the blood-pressure changes are positive and increase with higher pressures.If change of pressure is determined.by attained pressure, this would explain the observation that some individuals and some races show no apparent increase of pressure with age, and would partially reconcile the conflicting views on the nature of unexplained hypertension. However, the evidence has shown only association, not causality.We wish to record our thanks to the people of the Rhondda Fach and Vale of Glamorgan who so willingly continue to c...

Serum Immunoglobulin Levels in Children with Acute Lymphoblastic Leukaemia and Their Mothers and Sibs

“…Radiation is the only leukaemogenic agent which is firmly established on the basis of studies on the survivors of the atomic bomb explosions in Japan (Bizzozero, Johnson, and Ciocco, 1966), and from data on therapeutic irradiation (Watkins, Fairley, and Scott, 1967). There is considerable evidence implicating viruses in the causation of malignancies including leukaemia in animals (Burdette, 1966).…”