Phenidone-ascorbic acid development in electronmicroscopic autoradiography

Ultrastructural changes associated with the induction of premature chromosome condensation in Vicia faba root meristem cells

PCC induction is regulated by several signaling pathways, and all observed effects associated with PCC induction are strongly dependent on the mechanism of action of each PCC inducer used. Electron microscopic observations of cells with symptoms of premature chromosome condensation (PCC) showed that the interphase chromatin and mitotic chromosomes differed with respect to a chemical compound inducing PCC. Induction of this process under the influence of hydroxyurea and caffeine as well as hydroxyurea and sodium metavanadate led to a slight decrease in interphase chromatin condensation and the formation of chromosomes with a considerably loosened structure in comparison with the control. Incubation in the mixture of hydroxyurea and 2-aminopurine brought about clear chromatin dispersion in interphase and very strong mitotic chromosome condensation. Electron microscopic examinations also revealed the characteristic features of the structural organization of cytoplasm of Vicia faba root meristems, which seemed to be dependent on the type of the PCC inducer used. The presence of the following was observed: (i) large plastids filled with starch grains (caffeine), (ii) mitochondria and plastids of electron dense matrix with dilated invaginations of their internal membranes (2-aminopurine), and (iii) large mitochondria of electron clear matrix and plastids containing protein crystals in their interior (sodium metavanadate). Moreover, since caffeine causes either the most effective loosening of chromatin fibrils (within the prematurely condensed chromosomes) or induction of starch formation (in the plastids surrounding the nuclei), this may be a proof that demonstrates the existence of a link between physical accessibility to chromatin and the effectiveness of cellular signaling (e.g., phosphothreonine-connected).

New pyrazoles incorporating pyrazolylpyrazole moiety: synthesis, anti-HCV and antitumor activity

Three series of novel pyrazole derivatives 2b-d, 4a-d and 6a-d were synthesized via two step procedure that utilizes hydrazonoyl chlorides 1a-d and enaminones 3a-d and 5a-d, respectively as starting materials. The structures of all the newly synthesized products have been established on the basis of analytical and spectral data. Moreover, some of the products 2-6 were tested against HCV and Subacute Sclerosing Panencephalitis (SSPE). In addition, compounds 2-6 were also tested for the inhibition of peroxynitrite-induced tyrosine nitration and antioxidant activity. The tested compounds are highly effective at very low concentration as anti-HCV, SSPE antioxidant and anticancer in the following ascending order 2d, 4c, 6b, 3b, 6c, 4d, 2b, 2c, 2a, 6a, 5b, 5a, 3a, 4b and 5c. It is worth to mention that all tested compounds are more potent than the reference standards used for comparing activity. All the measurements revealed that the mechanism of action of the anti cancer activities of all the tested compounds is topoisomerase I inhibitor.

Putative acidic amino acid transmitters in the cerebellum. II. Electron microscopic localization of transport sites

In structurally preserved cerebellar slices, the sites of high affinity uptake of acidic amino acids were analyzed using the nonmetabolizable analogue, D-[3H]aspartate. Electron microscopic autoradiography showed the greatest accumulation of grains to be over glial structures. The labelling of the perikarya, dendrites and axons of the putatively glutamatergic granule cells was very low. However, "hypothetical grain" analysis indicated that the terminals of these cells are probable sources of radioactivity even though they contained less than 9% of the total grains in the molecular layer. The resolution of the autoradiographic technique did not permit definitive conclusion, as the parallel fibre terminals are too small and are ensheathed by thin glial processes. Nevertheless, further supporting evidence for some D-[3H]aspartate uptake into parallel fibre terminals was obtained using mechanically chopped cerebellar slices in which compared with glia presynaptic structures are selectively preserved. It is concluded that in line with hypotheses relating to the compartmentation of glutamate metabolism, the principal sites of uptake of acidic amino acids in the cerebellum are the glial cells. The results have clear implications regarding the use of high affinity uptake as a marker for glutamatergic nerve terminals.

Localization of high affinity [3H]glycine transport sites in the cerebellar cortex

A study was made of [3H]glycine uptake sites in a preparation greatly enriched in large pieces of the cerebellar glomeruli (glomerulus particles) and in morphologically well preserved slices of rat cerebellum. Electron microscopic autoradiography revealed that of the neurones in the cerebellar cortex only Golgi cells transported [3H]glycine at the low concentration used. Glial cells also took up [3H]glycine but to a lesser extent than the Golgi neurons. It was also confirmed that under comparable conditions Golgi cells transport [3H]GABA. Kinetic studies utilizing the Golgi axon terminal-containing glomerulus particles showed that glycine is a weak non-competitive inhibitor of [3H]GABA uptake (Ki over 600 microM vs the Kt of about 20 microM) and that GABA is an even weaker inhibitor of [3H]glycine uptake. These observations indicated that glycine and GABA do not share the same carrier. Quantitative electron microscopic autoradiography showed that the uptake of the two amino acids, in terms of the unit area of labelled Golgi axon terminals, was not additive. In contrast, their uptake in terms of unit protein was strictly additive. These observations, the first relating to unit volume and the latter to the total volume of Golgi terminals, are consistent with the view that there are two biochemically separate populations of Golgi neurons, one transporting glycine the other GABA. Saturable [3H]strychnine binding was detected in the preparations of glomerulus particles, but in comparison with those from the spinal cord the affinity was lower and [3H]strychnine was not displaced by glycine. Available information on glycine receptors, however, suggest that this should not exclude the possibility of strychnine resistant glycine receptors in the rat cerebellum.

Resolution of a gold latensification-elon ascorbic acid developer for Ilford L4 emulsion

The electron-microscopical autoradiographical resolution of a gold latensification-elon ascorbic acid (GEA) developer for Ilford L4 emulsion was determined experimentally, using radioactive line sources of tritiated albumin (Heijnen and Geuze, 1977). For sections with a thickness of 62 nm (SD +/- 11), which were covered with a carbon layer about 5 nm thick and a slightly overlapping monolayer of L4 silver bromide crystals, the measured half-distance (HD) of resolution was 115 nm. This improvement in resolution, the high efficiency of the GEA developer for L4 emulsion (Wisse and Tates, 1968), and the excellent visibility of the cellular structures under the small silver grains, mean that the L4-GEA combination deserves preverence as a method for quantitative electron-microscopical autoradiography.