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PubMedDate not supplied

[Gastric leiomyoblastoma. (Review of the literature in the light of a case)].

Gastric leiomyoblastoma is a rare benign neoplasm, arising from the smooth muscle cell, that may become malignant. The most important symptoms are epigastric pain, sideropenic anaemia and upper GI bleeding, but frequently the diagnostic iter is difficult and definitive diagnosis is made only with histology after laparotomy. A personal case is reported and Literature data are reviewed; stress being laid on the uncertain biological evolution that influence mostly the choice of therapy.

Esophagoscopy↗
PubMed1999

Following angiogenin during angiogenesis: a journey from the cell surface to the nucleolus.

Angiogenin is a potent inducer of new blood vessel formation. It binds to high-affinity endothelial cell-surface receptors and, with lower affinity, to extracellular matrix. Angiogenin is the only angiogenic factor known to exhibit ribonucleolytic activity. It belongs to the pancreatic RNase superfamily of proteins. Angiogenin is the only member of the superfamily able to stimulate angiogenesis. Although the catalytic activity of the protein is rather weak, it is critical for its angiogenic properties. Angiogenin is specifically endocytosed by endothelial cells and transported to the nucleus, where it accumulates in the nucleolus. Also, the nuclear location of the angiogenic factor appears to be necessary for its angiogenic activity. The mechanism of action of the protein seems to be unusual, since it does not fit into the current paradigm of how exogenous regulatory polypeptides, including other angiogenic factors, work. Here, the role of transport of angiogenin from the cell-surface into the nucleolus and of its intracellular/nuclear mode of action in stimulation of angiogenesis is discussed.

Animals↗
PubMed1999

Lateral genomics.

More than 20 complete prokaryotic genome sequences are now publicly available, each by itself an unparalleled resource for understanding organismal biology. Collectively, these data are even more powerful: they could force a dramatic reworking of the framework in which we understand biological evolution. It is possible that a single universal phylogenetic tree is not the best way to depict relationships between all living and extinct species. Instead a web- or net-like pattern, reflecting the importance of horizontal or lateral gene transfer between lineages of organisms, might provide a more appropriate visual metaphor. Here, I ask whether this way of thinking is really justified, and explore its implications.

Evolution, Molecular↗
PubMed2000

Function of fusion regulatory proteins (FRPs) in immune cells and virus-infected cells.

Two molecules that regulate cell fusion have been identified and designated fusion regulatory protein-1 (FRP-1) and FRP-2. FRP-1 is a complex composed of a glycosylated heavy chain and a nonglycosylated light chain that are disulfide linked. FRP-1 heavy chain is identical to 4F2/CD98 heavy chain, whereas FRP-2 is identical to integrin alpha3 subunit. The FRP-1 heavy chain is a multifunctional molecule: that is, fusion regulator, amino acid transporter, integrin regulator, comitogenic factor, Na+-Ca2+ exchanger, oncogenic protein, and so on. Several aspects of the structure and function of the FRP-1 system are reviewed: fusion regulatory molecular mechanisms, cross-talk between the FRP-1 and integrin, the FRP-1 system as amino acid transporter, and FRP-1-mediated T-cell activation. The FRP-1 system is involved in virus-mediated cell fusion and multinucleated giant cell formation of blood monocytes. Monoclonal antibodies against human FRP-1 heavy chain induce polykaryocytes that have properties as osteoclasts. Multiple steps participate in molecular mechanisms regulating cell fusion. The FRP-1 heavy chain supports amino acid transport activity and the FRP-1 light chains have recently been cloned as amino acid transporters that require association with the heavy chain to exhibit their activity. Novel pathways for monocyte-dependent regulation of T-cell activation have recently been found that are mediated by the FRP-1 system. In conclusion, the FRP-1 molecules are essential factors for basic cellular functions.

Amino Acids↗
PubMed2001

Prolegomenon to a general biology.

This chapter is a slightly modified version of Chapter 1 of my book, Investigations. I discuss "autonomous agents," the origin of life, autocatalytic sets of polymers, work cycles, puzzles-about evolutionary theory, and the birth of a general biology dealing with biospheres anywhere in the universe.

Behavior↗
PubMed1996

Astrophysical and biological constraints on radiopanspermia.

We have carried out a series of calculations involving bacteria and viruses embedded in dust grains, which are ejected from our solar system by radiation pressure and travel through space to other star systems. Under many conditions this type of panspermia is impractical, primarily because the ultraviolet (UV) radiation of the present Sun inactivates the micro-organisms. However, if the organisms are shielded by an absorbing material like carbon and if ejection takes place in the red-giant phase of a one solar mass star like our Sun, there is a significant probability that the micro-organisms can reach another star system alive (i.e. with only sub-lethal damage from UV and ionizing radiation). In addition to panspermia with viable micro-organisms, it is possible to seed the Galaxy with inactivated ones whose DNA and RNA fragments may provide the initial information necessary to start biological evolution in favourable environments.

Astronomical Phenomena↗