Biomedical subjects

I Schmidt

Publications and source records attributed to I Schmidt.

165 records · Page 10Linked to original sources

PubMedDate not supplied

[Total synthesis of human big gastrin I and the 32-leucine analogue (author's transl)].

Synthetic Peptide Hormones, Human Big Gastrin I. A new total synthesis of the tetratriacontapeptide amide corresponding to the proposed primary structure of human big gastrin I is described. The synthetic route was based on the preparation of six suitably protected fragments, related to sequence 28-34, 23-27, 21-22, 15-20, 9-14, and 1-8, to be used as building blocks for the total synthesis. The protecting groups were selected according to the Schwyzer-Wünsch strategy of maximum side chain protection based on tertiary alcohols, also for the imidazol function of histidine. Subsequent assembly of the six fragments by three different pathways using the highly efficient Wünsch-Weygand condensation procedure to ensure minimum racemization, followed by deprotection of the synthetic products via exposure to trifluoroacetic acid and final purification by ion-exchange chromatography on DEAE-Sephadex A-25 and partition chromatography on Sephadex G-25, led to human big gastrin I, homogeneous within the limits of the analytical methods used. The biological activity of the synthetic product proved to be 50 percent higher than that of human little gastrin I. The 32-leucine analogue of human big gastrin I was prepared in the same way.

Amino Acid Sequence↗

PubMedDate not supplied

[Effect of clonazepam on neuronal activity in the sensomotor cortex of rat brain].

In tests on flaxedyl immobilized rats the effect of clonazepam on the action produced by gamma-aminobutyric acid, acetylcholine and L-glutamate, delivered microionophoretically to neurons of the sensomotor brain cortex, was investigated. Clonazepam was found to potentiate the inhibiting action of gamma-aminobutyric acid and reduce the exciting effect of acetylcholine and L-glutamate on the spontaneous neuronal activity. The ability of clonazepam, like other tranquilizers of the benzodiazepine series, to augment the sensitivity of the receptive neurons formations to gamma-aminobutyric acid and also influence the ionic permeability of the post-synaptic membrane is suggested.

Acetylcholine↗

PubMedDate not supplied

Anaerobic ammonia oxidation with nitrogen dioxide by Nitrosomonas eutropha.

Nitrosomonas eutropha, an obligately lithoautotrophic bacterium, was able to nitrify and denitrify simultaneously under anoxic conditions when gaseous nitrogen dioxide (NO2) was supplemented to the atmosphere. In the presence of gaseous NO2, ammonia was oxidized, nitrite and nitric oxide (NO) were formed, and hydroxylamine occurred as an intermediate. Between 40 and 60% of the produced nitrite was denitrified to dinitrogen (N2). Nitrous oxide (N2O) was shown to be an intermediate of denitrification. Under an N2 atmosphere supplemented with 25 ppm NO2 and 300 ppm CO2, the amount of cell protein increased by 0.87 mg protein per mmol ammonia oxidized, and the cell number of N. eutropha increased by 5.8 x 10(9) cells per mmol ammonia oxidized. In addition, the ATP and NADH content increased by 4.3 micromol ATP (g protein)-1 and 6.3 micromol NADH (g protein)-1 and was about the same in both anaerobically and aerobically grown cells. Without NO2, the ATP content decreased by 0.7 micromol (g protein)-1, and the NADH content decreased by 1.2 micromol (g protein)-1. NO was shown to inhibit anaerobic ammonia oxidation.

Adenosine Triphosphate↗