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Biomedical subjects

A G Romualdez

Publications and source records attributed to A G Romualdez.

5 recordsLinked to original sources
PubMed1976

Further studies on the C5-derived chemotactic factor for tumor cells.

A factor has been studied that is chemotactic in vitro for Walker carcinosarcoma and Novikoff hepatoma cells of rats and for murine mastocytoma cells, but not for neutrophils. This chemotactic factor is generated by the incubation of normal serum with a crude extract from tumor cells. The generation of the tumor cell chemotactic factor is time and temperature dependent and results in greater than 30% reduction of serum complement activity. The tumor cell chemotatic factor appears to be a small cleavage product of the fifth complement component (C5) which binds to serum globulin. This has been shown by the use of agammaglobulinemic serum. By the use of isolated C5 fragments there is direct evidence that the tumor cell chemotactic factor is structurally derived from a larger C5 leukotactic fragment. The study of tumor cell chemotaxis, particularly the involvement of the complement system in this phenomenon, may suggest a novel approach to the investigation of the mechanism of metastasis in the malignant process.

Agammaglobulinemia↗
PubMed1976

Relationship between the C5 peptides chemotactic for leukocytes and tumor cells.

A reciprocal relationship has been demonstrated between the generation of the leukotactic and the tumor cell chemotactic peptides from C5. Trypsin-produced C5 leukotactic peptides can be converted into tumor cell chemotactic factors by treatment with tumor cell extracts or by incubation with the alpha-globulin chemotactic factor inactivator (CFI) isolated from human serum. A similar CFI isolated from rat serum can, like the alpha-globulin CFI from human serum, generate the tumor cell chemotactic factor from the whole human serum. These results suggest that the tumor cell chemotactic factor derives from the same portion of the C5 molecule as the leukotactic peptide. Furthermore, it appears that the critical change may be cleavage of the amino-terminal portion of the leukotactic peptide. In addition, it has been shown that most normal tissues contain an enzyme-like material that is able to generate in normal human serum a factor chemotactic for tumor cells. The implications of these findings are discussed.

Alpha-Globulins↗
PubMed1975

A unique complement derived chemotactic factor for tumor cells.

A factor chemotactic for Walker carcinosarcoma and Novikoff hepatoma tumor cells can be generated by incubation of serum with an extract from tumor cells. The chemotactic factor has no activity for neutrophilic leukocytes, and three factors chemotactic for leukocytes are not chemotactic for tumor cells. By the use of complement deficient serums as well as purified complement components, the chemotactic factor for tumor cells has been found to be a fragment of the fifth component (C5) of complement and appears to result from direct interaction of C5 with an enzyme in the extract. The chemotactic factor for tumor cells can be classified as a functionally unique fragment of C5 that may significantly influence the behavior of tumor cells in vivo.

Animals↗