Studies of Functional Neural Tumors VII. Urinary Excretion of Phenolic Pyruvic Acids

Quality control of benserazide-levodopa and carbidopa-levodopa tablets by capillary zone electrophoresis

In modern practice, the treatment of Parkinson's disease and syndrome is carried out using pharmaceutical formulations containing a combination of levodopa and a decarboxylation inhibitor (carbidopa or benserazide). Two pharmaceutical formulations were quantified by capillary zone electrophoresis using two procedures which differed only in the kind of background electrolyte used. One procedure used a 25 mM phosphate buffer, pH 2.5, while the second one used a 25 mM borate buffer, pH 8.5. The electrophoretic analysis was carried out using an uncoated fused- silica capillary, a separation voltage of 20 kV with currents typically less than 60 microA, and spectrophotometric detection at 205 nm. Calibration curves were performed for levodopa (concentration range 1-100 microg/mL), for carbidopa and benserazide (1-50 microg/mL), and the plots of the peak area versus concentration were found to be linear with a correlation coefficient better than 0.9990. Satisfactory results were obtained when commercial tablets were analyzed in terms of accuracy (98-102%), repeatability (0.6-2.0%), and intermediate precision (1.1-2.6%).

Adrenocortical response to single and repeated doses of chloroform in rats

The influence of single and repeated doses of chloroform on the adrenocortical function was studied in young male albino rats. One day after oral administration of a single dose of 1.5 g chloroform/kg body weight, adrenal hypertrophy developed and persisted for at least 12 days. The adrenal cholesterol content started to drop 3 h after the application, remained low for 1 day, then increased and remained elevated during the next 12 days. The plasma corticosterone content increased 15 min after the treatment and remained high during the next 4 h; 6 h after the treatment, when the anesthetic effects of CHCl3 had disappeared, it decreased somewhat; after 12 h it increased again, and the peak value was observed after 1 day. This was followed by a gradual drop, and after 8 days it reached the normal level. A second dose, administered 4 or 8 days after the first one, was still capable of stimulating the adrenocortical function. This was evidenced 24 and 48 h after the second dose. The response, however, was smaller than that observed after a single dose of the same stressor. The influence of a single dose of chloroform on corticosterone decay in the circulation 1 and 9 days after treatment, was tested in adrenalectomized rats injected with non-radioactive corticosterone, and in intact rats injected with 1,2-3H-corticosterone. Results for the adrenalectomized animals were inconclusive, whereas those for the intact ones proved that the treated animals metabolized corticosterone as well as the controls did.

Gas chromatographic determination of urinary vanilglycolic acid, vanilglycol, vanilacetic acid and vanillactic acid-chemical parameters for the diagnosis of neurogenic tumours and the evaluation of their treatment

A gas chromatographic method is described for the determination of urinary vanilglycolic acid, vanilglycol, vanilacetic acid and vanillactic acid as their trimethylsilyl derivatives. These metabolites are chemical parameters for the dignosis of neurogenic tumours. Their determination is especially recommended in order to evaluate the effect of the therapy. Results in normals and controls are given. Data in a number of selected patients with neuroblastoma, ganglioneuroma and phaeochromocytoma are presented and discussed.

The function of the retina in the perfused eye

The data show that the enucleated eye of the cat can be maintained in apparently physiologically functioning condition by appropriate arterial perfusion. Under appropriate conditions, photically evoked electrical mass responses can be recorded from various parts of the isolated, perfused eye for 8 to 10 hours. ERGs as well as responses from axonal bundles of the optic nerve exhibit shapes, amplitudes and time courses comparable to their counterparts in vivo. Homeostasis of the perfusion ensures the stability of these light-evoked electrical responses. Transient changes in biophysical parameters of the perfusate rapidly induce marked, although reversible, changes in the amplitudes of b-waves of the ERGs. Increases or decreases in the flow rate of the perfusate induce parallel increases or decreases in the amplitudes of the b-waves as well as of the optic nerve responses. Similar alterations in the oxygen concentration of the perfusate induce similar and proportional changes in the amplitudes of the b-waves. It is concluded, that low flow rates of hemoglobin-free perfusate induce hypoxia; consequently, acceleration of the flow can compensate for hypoxia in a certain range. Previous studies on the effects of and recovery after transient hypoxia in mammalian retina are in concordance with the present data. Progressive decrease of temperature induces gradual and reversible reductions in the amplitudes of the b-waves and increases their latencies and peak-times. It is suggested, that initial hypothermia, which occurs during the period of cannulation, reduces the deliterious effects of the coincident unavoidable hypoxia on retinal neuronal elements. Since light-evoked electrical responses can be maintained for many hours in these preparations and since movements of cardiovascular and respiratory origin, invariably present to varying extent in the in vivo experiments, are eliminated, this preparation is suitable for intracellular recordings from neuronal elements of the retina. Potentials were recorded from cells in various layers of the retina of the cat; intracellular recordings from horizontal cells (S-potentials) are described in detail. Spectral analysis of S-potentials allowed to distinguish between three types according to their inputs: a mixed, rod-cone type, which was most frequently encountered, a pure cone- and a pure rod-type. Light- and electronmicroscopic investigation of the retina after perfusion revealed that (1) the extent of cellular damage depends on the flow rate of the perfusate; (2) little cellular damage is observed if medium flow rates, which maintain physiologic responsiveness of the isolated eye to light, were applied for two hours; (3) high flow rates applied for two hours, or medium flow rates applied for 7 hours appear to induce cystic changes in the pigment epithelium, but only minor changes in the cells of the inner nuclear layer.