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[Multicellular spheroids for use in radiobiological experiments].

Cell spheroids are conglomerates of closely arranged cells with reciprocal effects among them. Spheroids are histologically similar to nodulary tumours. Cells constituting these spheroids are heterogenous in their sensitivity to X-rays and fast neutrons. Radiosensitivity of cells in a small spheroid is lower than that of similar cells grown in a monolayer.

Cell Survival↗
PubMed1982

Supracellular structural principle of multicellular organisms.

All the supracellular structures composed of compact aggregates of constituent units are subordinate to a single structural principle. It is a particular space division called equilibrium space division (ESD) by the author. EDS is a geometrical expression of the second law of thermodynamics corresponding to a state of minimized potential energy of the system of constituent units assembled by uniform or polarized centripetal force. It is a statistical process under incomplete mechanical restrictions and cannot entirely be reduced to deterministic mechanisms. Supracellular structures are accordingly not directly prescribed by genetic information based upon the template function of DNA molecules. Blood vessels are essentially localized on the edges of ESD, so that their geometry is influenced by this particular space division. Some geometrical parameters of arteries are theoretically derived from the geometry of ESD, partly with the aid of a model of space division by uniform beta-tetrakaidecahedra, which approximately replaces ESD.

Animals↗
PubMed1980

[Multicellular spiking of the cat somatosensory cortex at rest and during spontaneous EEG activation].

In chronical experiments on unanesthetized unrestrained cat multineuronal discharges and EEG were simultaneously recorded from the somatosensory cortex by the same semimi-croelectrode. The discharges were automaticaly separated into three amplitude levels. Three types of basic multineuronal discharge patterns were classified: continuous, bursting and grouped ones. During visually similar periods of spontaneous EEG activation the multineuronal discharges exhibited different and variable changes. The amplitude discrimination method revealed at different discharge levels parallel discharge frequency rise or fall or absence of changes in the average frequency. The kind of multineuronal discharge reorganization depended on the intensity of the EEG activation. The computer analysis showed the prevalence of the excitatory effects (55%), but inhibitory changes were also rather significant (21%). The experimental data suggest a complicated and highly dynamic functional structure of the spontaneous brain activation process at the level of neuronal populations.

Animals↗
PubMed1995

The (2'-5')oligoadenylate synthetase is present in the lowest multicellular organisms, the marine sponges. Demonstration of the existence and identification of its reaction products.

We have proved the presence of (2'-5')oligoadenylates [(2'-5')An] and oligoadenylate synthetase [(2'-5')An synthetase] in the marine sponge Geodia cydonium. (2'-5')An isolated from sponge crude extract competed with authentic (2'-5')An for binding to polyclonal antiserum against (2'-5')An. HPLC analysis revealed the presence of nucleotides eluting with molecular markers for (2'-5')A oligomers. The biological activity of sponge (2'-5')An was demonstrated by inhibiting the protein biosynthesis in rabbit reticulocyte lysate. The activity of the (2'-5')An synthetase, present in crude sponge extract, was found to be high compared to that in mammalian interferon-treated cell extract. The (2'-5')An synthetase from sponge extract binds to poly(I).poly(C) as does the mammalian enzyme. Western blot analysis with antibodies to recombinant rat 43-kDa (2'-5')An synthetase revealed in sponge immunologically related proteins with molecular masses of approximately 110, 65, 61 and 34 kDa. We conclude, that the (2'-5')An system has evolved from receptors and enzymes involved in cell adhesion and/or growth control.

2',5'-Oligoadenylate Synthetase↗