The role of cellular polyploidy in the regeneration of the cirrhotic liver in rats and humans.

Polyploidy is a condition in which a cell has multiple diploid sets of chromosomes. Two forms of polyploidy are known. One of them, generative polyploidy, is characteristic of all cells of the organism, while the other form develops only in some somatic tissues at certain stages of postnatal ontogenesis.

An appreciation of the prescience of Don Gilbert (1930-2011): master of the theory and experimental unravelling of biochemical and cellular oscillatory dynamics.

We review Don Gilbert's pioneering seminal contributions that both detailed the mathematical principles and the experimental demonstration of several of the key dynamic characteristics of life. Long before it became evident to the wider biochemical community, Gilbert proposed that cellular growth and replication necessitate autodynamic occurrence of cycles of oscillations that initiate, coordinate and terminate the processes of growth, during which all components are duplicated and become spatially re-organised in the progeny. Initiation and suppression of replication exhibit switch-like characteristics, that is, bifurcations in the values of parameters that separate static and autodynamic behaviour.

Melatonin as the most effective organizer of the rhythm of protein synthesis in hepatocytes in vitro and in vivo.

Recent data has extended a large array of melatonin functions by the discovery of melatonin's involvement in the organization and regulation of the rhythm of intracellular protein synthesis. An ultradian rhythm in total protein synthesis has been detected in primary hepatocyte cultures 5 min after addition of 1-5 nM melatonin to the medium. The melatonin effect was mediated via its receptors (as shown in experiments with luzindole), leading to the cell synchronization as well as the mean rate of protein synthesis rate being increased.

Involvement of protein kinases in self-organization of the rhythm of protein synthesis by direct cell-cell communication.

Primary cultures of rat hepatocytes grown on slides were studied in serum-free medium. Ultradian protein synthesis rhythm was used as a marker of synchronization of individual oscillations, resulting in the formation of a common rhythm of the cell population, i.e.

Direct cell-cell communication: a new approach derived from recent data on the nature and self-organisation of ultradian (circahoralian) intracellular rhythms.

Recent data concerning ultradian (circahoralian) intracellular rhythms are used to assess the biochemical mechanisms of direct cell-cell communication. New results and theoretical considerations suggest a fractal nature of ultradian rhythms and their self-organisation. The fundamental and innate nature of these rhythms relates to their self-similarity at different levels of cell and tissue organisation.

The Embryos Obtained from the Karyoplasts of Starfish Oocytes: Their Development and Sensitivity to Cytostatic Neurotransmitter Antagonists: (karyoplasts/oocytes/sensitivity to neurochemicals).

Karyoplasts obtained from full-grown oocytes of the starfish Aphelasterias japonica have practically no cytoplams and are incapable of maturation. Karyoplasts of oocytes of starfishes Marthasterias glacialis and Acanthaster planci have the cytoplasm (10%-15% of the total karyoplast volume) and are often capable of maturation, fertilization and one or several cleavage divisions. The embryoskaryoplasts completely lose supersensitivity and retain usual sensitivity to cytostatic antagonists of neurotransmitters.