Regressional changes of human cerebellar cortex and hypoglossal nucleus during development.

In the development of nervous system, two processes are of a particular interest. It is well known that after a primary migration of cells, there appears a consecutive regression in cellular number, closely connected with the maturation of the nervous system. The dynamics of this reduction was investigated following the changes in number of cells in nucleus hypoglossus as well as that of Purkinje cells in two structures of cerebellar cortex--in vermis and in hemispheres. Cell nuclei were counted using the stereological technique, after a usual preparation. Data were collected from 20 human brains of different gestation age, i.e. at 12.5, 14, 17.5, 19.5, 24, 31, weeks of gestation and 6 day old newborn. After the graphical and numerical analysis of the data obtained, an adequate mathematical model was proposed. It is confirmed that a close agreement between biological data and decreasing two-exponential equation can be demonstrated, pointing out that the cellular reduction shows a proportional relation. The possible explanation could be that only the cells forming proper and useful connections and entering the informational system have a privilege to survive, and that all improper contacts lead to the rejection of cells or even of groups of cells.

Effect of simultaneous Tc-99m diethyl-IDA and sulfobromophthalein administration on liver excretory function in rats.

Competition of diethyl-IDA and BSP during their synchronous passage through the liver was examined on an animal model. Rats were divided in three groups, according to the amount of diethyl-IDA or BSP administered. No significant influence of diethyl-IDA on the liver uptake of BSP was noticed compared to the controls, while BSP demonstrated a significant inhibitory effect on diethyl-IDA plasma-activity decrease. On the biliary pole of hepatocyte, a reciprocal inhibitory influence of both compounds was present, with significantly diminished biliary excretion of both BSP and diethyl-IDA. As the input of BSP was not decreased, there evidently appeared a storage of BSP within the liver. A mathematical model of both plasma and bile changes of the concentration (or activity) of these compounds was also proposed. For the vascular compartment the model is correct, while biliary excretion of diethyl-IDA is significantly changed in presence of BSP and the satisfactory fit cannot be easily obtained.

A routine fitting of kinetic data to sums of exponentials with a programmable calculator.

The effects of prolonged ingestion of ethyl alcohol on the elimination kinetics of bromsulphalein (BSP) from the plasma and the excretion of the dye into bile after a single intravenous injection into the circulation of the rat were examined by means of the colorimetrical technique. Simple numerical methods for fitting the experimental data to polyexponential and convex upward functions were also proposed. Two multioptional programs written for the Texas Instrument 59 programmable calculator and for the Sharp 1500 pocket computer were developed which provide for fully automated exponential stripping of pharmacokinetic data and which will allow workers to calculate the numerical values of all the coefficients and exponents for the tracer function fitting the monotone sequences of data.

Bromsulphalein plasma kinetics after obstruction of the common bile duct in rats: curve fitting with a programmable calculator.

Plasma kinetics of bromsulphalein (BSP) after a single injection into the bloodstream of the rat with total obstruction of the common bile duct was examined. The concentrations of BSP were determined colorimetrically. A monoexponential plus a general first-degree function in time with four unknown parameters was fitted. Two programs were developed for the Texas Instruments 59 programmable calculator to estimate the values of all the parameters by an iteration procedure. The programs executed at about twice normal speed.

A numerical method for biphasic curve fitting with a programmable calculator.

Elimination kinetics of bromsulphalein (BSP) after a single injection into the circulation of rats were examined by means of a four-compartment model. BSP plasma concentrations were measured colorimetrically. A program written for the Texas Instruments TI-59 programmable calculator is presented, which will calculate the fractional blood clearance of BSP using an iteration procedure. A simple method of fitting biphasic decay curves to experimental data is also proposed.