A reliable and sensitive method for the simultaneous determination of dopamine, noradrenaline, 5-hydroxytryptamine and 5-hydroxy-indolacetic acid in small brain samples

A sensitive and reliable fluorometric method for the simultaneous determination of dopamine, noradrenaline, 5-hydroxytryptamine and 5-hydroxy-indol acetic acid in small samples of brain tissues is described. The procedure is based on solvent extraction; catecholamines are oxidized by the Chang's method and 5-hydroxytryptamine and 5-hydroxy-indol acetic acid determined by reaction with o-phthalaldehyde, alpha-methyl-p-tyrosine causes a negligible interference with the procedure. Results of determination of these amines in different brain areas are reported.     

Genetic determination of the mitochondrial adenine nucleotide translocation system and ITS role in the eukaryotic cell

On integrating experimental data published previously, the following picture of the mitochondrial adenine nucleotide (AdN) translocation system is being presented: 1. The AdN translocation system serves not only to transport ATP synthesized within mitochondria into the cytosol but also to transport cytosolic ATP into the mitochondria when oxidative phosphorylation is not functioning. 2. The AdN translocator is coded for by nuclear genes and the mitochondrial protein synthesis is not involved in its formation. 3. The AdN translocation system must be preserved and functioning even in cells which could dispense with oxidative phosphorylation. It assures appropriate concentrations of intramitochondrial ATP. 4. The intramitochondrial ATP is required for normal replication of mitochondrial DNA. Tis supports the view that the mitochondrion is a self-replicating semi-autonomous organelle. 5. The appropriate concentration of ATP must be present in mitochondria to make possible cell growth or multiplication. This points to a direct or indirect role of mitochondria in the control of cell proliferation.     

Length of human constitutive heterochromatin in relation to chromosomal contraction

Summary Linear measurement of blocks of constitutive heterochromatin and the euchromatin portion 1q-h in three members of a family was used to study the dependence of the size of C blocks on the degree of chromosomal contraction. The results demonstrate that the size of heterochromatin portions decrease regularly with an increases of the degree of euchromatin contraction. The dependence was found to be linear, except for mitoses with an extremely high or low degree of contraction. The finding was used for the development of a new method of evaluation of constitutive heterochromatin.     

Metabolism of benzo(a)pyrene by human lung microsomal fractions

The metabolism of benzo(a)pyrene was studied using microsomal fractions obtained from human lung derived at either resection or autopsy. The rates of metabolism and metabolite distribution were monitored using high pressure liquid chromatography and the metabolic rates were noted to be similar to those obtained using rat lung microsomes. In contrast to the rat, human lung microsomes appear to form a higher percentage of the 7,8-dihydro-7, 8-diol or 9,10-dihydro-9, 10-diol of benzo(a)pyrene as a fraction of the total metabolites. However, there was a significant variation among the human lung microsomal preparations which might reflect the clinical diagnosis and/or individual variation.     

Germination inhibitors in the pine seed coat

Inhibitors from (Pinus pinea L.) seed coats were separated using paper chromatography, thin layer chromatography, and a Sephadex G-10 column. The inhibitory activity was resolved into several fractions. One of these behaved similarly to abscisic acid. It has exhibed the same properties as ABA in thin-layer chromatography, paper chromatography, and Sephadex G-10 chromatography and in UV absorption and fluorescence spectra. These germination inhibitors, present in the seed coats, are involved in the regulation of P. pinea seed germination.Abbreviations ABA abscisic acid - TLC thin-layer chromatography     

Adaptation to chronic hypobaric hypoxia and sexual hormones

The role of the gonads and their hormones on body weight was studied in rats of both sexes submitted to chronic hypoxia and their controls at sea level atmospheric pressure. Intact rats were exposed to either 4 700 or 6 000 m simulated altitude in a hypopressure chamber. Castrated rats and castrated rats daily injected with either 0.5 mg of testosterone or 20 microgram of estradiol or the vehicle, were exposed to the higher altitude. The rat weight was recorded for a period of at least eight weeks. All groups of hypoxic male animals increased their weight significantly less than the controls at sea level. Also in castrated females and in castrated injected with testosterone or the vehicle the same pattern of weight curves was observed. On the contrary, groups of intact females and castrated females injected with estradiol did not show significant differences between hypoxic and control animals. Only in a group of smaller intact females (50-80 g) the body weight increase was significantly diminished by exposure to either 4 700 or 6 000 m simulated altitude.     

Growth inhibition of a MC-induced mouse sarcoma by TCGF (IL 2)-containing preparations

Summary Supernatants from Con A-stimulated rat spleen cell cultures containing T cell growth factor inhibited growth of a transplantable 3-methylcholanthrene-induced sarcoma in syngeneic mice. The tumour-inhibitory effects were dependent on the concentration of T cell growth factor and repeated injections of the supernatants.     

Inhibition of translation by the fungal toxin cyclopiazonic acid

Cyclopiazonic acid is a toxic metabolite of fungal origin that inhibits protein synthesis in intact HeLa cells and eukaryotic cell-free systems. It has been shown that cyclopiazonic acid blocks the GTP- and EF-1-dependent binding of (³H)Phe-tRNA to 80S ribosomes. Moreover the translocation of N-Ac-(³H)Phe-tRNA by 80S ribosomes that takes place in the presence of EF-2 and GTP is also halted by cyclopiazonic acid. It is concluded that this drug affects a ribosomal site involved in the alternative interaction of elongation factors EF-1 and EF-2.