Further Studies of the Kinetics of Glucose Utilization. I. A New Method of Data Analysis*

Abstract

Evidence is presented to show that the extreme variation in rate constants for blood glucose disappearance reported by different laboratories is due to the use of an incorrect equation and/or an incorrect method of data analysis. It is demonstrated that graphic (semi-log) methods are too insensitive to be used to justify equations describing blood glucose disappearance. The correct equation is shown to be one of exponential form containing an added constant term which in the normal subject is significantly less than the fasting level of blood glucose. A new method of data analysis (slope analysis) is described which results in the same specific rate constant, K, regardless of the equation employed. This method is made practical by the introduction of a mechanical slope reader which eliminates excessive calculations.

Mannose Utilization in Man*

“…The synthesis of six or more points into a single value characterizing tolerance is more logical for comparative studies than one or more single values at specific times. Whether K should be calculated from total hexose values, or from the increments above the fasting value has also led to much discussion and elaboration (31)(32)(33) without any clear evidence of practical or theoretical superiority of either method. There is some suggestion (33) that the disappearance rate of the absolute glucose level is better related to glucose utilization than the disappearance of increment blood glucose.…”

Factors controlling the washout of the interstitial space of the isolated, perfused rat heart

“…First, the logarithmic form is an insensitive way of showing change, and a fit is only meaningful for very precise data or for data covering a wide range of values. Secondly, although the addition of a constant C to the equation Y = Yoe-kt to give Y = Yoe-kt + C theoretically changes the straight line plot (log Y against t) to a curve, in practice a value of C sufficient to decrease the slope by 48 % does not significantly alter the fit to a straight line (Hlad, Elrick & Arai, 1959). In order to overcome these limitations, the washout data were first examined by plotting AY/At against Y, where AY is the amount of solute coming out in successive, equal intervals of time (At), and Y is the amount in the heart at those times.…”

The Metabolism of Gamma Globulins in Myeloma and Allied Conditions*

“…Nosslin's analysis (29) was applied to the data of the present investigation in a form based on the model shown in Figure 5. The data are plotted on a linear scale, and first derivatives of the plasma (P) and first and second derivatives of the cumulated urinary (U) curves are determined mechanically (30). Radioactivity in the degradation products distribution space (I) is determined from k, and the first derivative of U by the relationship dU = k51.…”