Linear Growth Velocity Research Articles

Body composition in uremic children and the effects of chronic hemodialysis

Chronically uremic children seldom grow normally; growth while on extended hemodialysis is usually not adequate. In order to delineate more precisely the components of this growth failure and the changes in body composition with chronic dialysis, 46 simultaneous measurements of total body water and of extracellular water (ECW) were determined in 24 children aged 2–17 yrs. The data were divided into two groups: uremic children dialyzed <3 mos and those dialyzed >6 mos. Published data of Cheek for healthy children of similar age were used for comparison. In the uremic children body weight (BW) and height (Ht) were below normal for age. ECW was significantly higher in both groups for Ht and BW, and its fluctuations tended to confuse interpretation of weight changes. In both groups, cell mass (CM), derived from calculated intracellular water, was low in relation to BW and Ht. While on dialysis, Ht, BW, and CM tended to increase; CM as per cent BW did not change, and increases in CM with Ht were less rapid than in normals. Correlation between changes in CM with change in Ht was low. Nutritional status was a factor in rate of increase in CM and in Ht. Although normal linear growth velocity may be observed on dialysis, catch-up growth is uncommon. Growth occurred without restoration of the normal relationship of CM to Ht. These studies have proved useful in defining the character of body composition in uremic children and in evaluating changes in body composition in individual patients with time, variations in caloric intake, and with growth.

On the dendritic growth of NH4C1 crystals from aqueous solutions

The dendrite growth of NH4C1 crystals from aqueous solutions was studied, and the linear growth velocity of the tip measured as function of supersaturation and temperature. At low supersaturation the increase of the growth velocity may be represented by a straight line, which however, seems to result from a superposition of a sequence of nonlinear functions. The temperature dependence of the straight line is rather strong. At higher supersaturation one observes a sudden increase of the growth velocity by a factor of almost ten. The growth velocity of these “fast” dendrites varies much stronger with supersaturation than that of the “slow” dendrites, while the temperature dependence is weaker.