Michael Nündel

α-Ketoglutarate Application in Hemodialysis Patients Improves Amino Acid Metabolism

In hemodialysis patients, free amino acids and α-ketoacids in plasma were determined by fluorescence HPLC to assess the effect of α-ketoglutarate administration in combination with the phosphate binde

THE KINETICS OF CONTACT INHIBITION IN MAMMALIAN CELLS

To elucidate the process of contact inhibition in mammalian cells, we investigated the kinetics of growth arrest in [3H]thymidine labelled embryonic chinese hamster (Cricetulus griseus L.) cells after the addition of various concentrations of unlabelled cells. It was observed that after the contact inhibition concentration had been reached, the cells grew undisturbed for one more generation. In the following 24 hr the concentration fell back to the level at the beginning of the experiment and stayed there.

Changes in the Concentrations of Hydroxyproline, Glycine and Serine in the Plasma of Haemodialysis Patients Undergoing, Erythropoietin Therapy

The concentrations of proline, hydroxyproline, glycine and serine were determined in the plasma of 39 haemodialysis patients and 18 healthy subjects, using liquid chromatography with fluorescence detection. Plasma concentrations of the N-terminal immunoreactive parathyrin were also measured. In haemodialysis patients, the plasma concentrations of glycine (p less than 0.01), hydroxyproline (p less than 0.05) and proline (p less than 0.10) were significantly increased, whereas the serine concentrations (p less than 0.01) were decreased, compared with those of the healthy controls. Haemodialysis patients showed greatly elevated plasma N-terminal immunoreactive parathyrin values (greater than 30 pmol/l), which showed a significant correlation with the hydroxyproline values (r = 0.79). Fourteen haemodialysis patients received erythropoietin therapy. In these patients, changes in the concentrations of plasma amino acids were observed up to one year after the beginning of therapy. In the course of the erythropoietin therapy, the plasma concentrations of glycine (p less than 0.05) and hydroxyproline (p less than 0.10) of the haemodialysis patients decreased, whereas the concentration of serine increased (p less than 0.05) to approximately normal values. The results indicate that erythropoietin therapy leads to a normalization of amino acid metabolism.

Synthesis of 10.11-epoxy-6.7-trans-2.3-trans-farnesyl-[2.3-3H] propenylether, a juvenile hormone efficient compound with very high specific radioactivity

Abstract 10.11-epoxy-6.7-trans-2.3-trans-farnesyl[2.3- 3 H] propenylether with a specific activity of 28.7 Ci m-mole −1 is synthesized. The four steps of synthesis and purification and identification are described.

An automatic counter for autoradiographed cells in Petri dishes.

A simple automatic counting device for cells on Petri dishes is described. The device is tested up to 1 × 104 cells (0·01 m)−2 and counts linearly without coincidence error. The counting time for each dish is c. 3– 4 min including the time required to place the dish in the apparatus.

Die Epidermis von Tenebrio molitor L. Puppen als Zielorgan für das Juvenilhormonanaloge 10.11-Epoxy-6.7-trans-2.3-trans-farnesylpropenyläther / The Epidermis of the Pupae of Tenebrio molitor L. as Target Organ for the Juvenile Hormone Analogue 10,11-Epoxy-6,7-trans-2,3-trans-farnesylpropenylether

In vivo tests give evidence that the epidermis is the target organ for the juvenile hormone of insects. A study of the distribution of injected 10,11-epoxy-6,7-trans-2,5-trawi-farnesyl-propenylether and of its metabolic products in epidermis, lymphae, and other organs demonstrated that the unaltered ether accumulates in the epidermis against a concentration gradient and is more slowly metabolised there than in the non-target organs.

Ein Receptorprotein für das Juvenilhormonanaloge 10.11-Epoxy-6.7-trans-2.3-trans-farnesylpropenyläther aus den Epidermiszellen der Puppen von Tenebrio molitor L. / A Receptor Protein for the Juvenile Hormone Analogue 10,11-Epoxy-6,7-trans-2,3-trans-farnesylpropenylether from the Epidermis Cells of the Pupae of Tenebrio molitor L.

A receptor protein was isolated from the epidermis cells of the pupae of Tenebrio molitor L. The affinity constant of the complex of this receptor protein and a juvenile hormone analogue was found to be 4.4 · 1010 l/mole. Its molecular weight is about 3.5·105. The isoelectric point is 4.4.