Tumor-Host Relationships

Fiber components are the principal energy source for colonic bacteria with a further contribution from digestive tract mucosal polysaccharides. Rate of fermentation varies with the chemical nature of the fiber components. Short-chain fatty acids generated by bacterial action are partiaUy absorbed through the colon waU and provide a supplementary energy source to the host. Therefore, dietary fiber is partiaUy caloric. The short-chain fatty acids also promote reabsorption of sodium and water from the colon and stimulate colonic blood flow and pancreatic secretions. Butyrate has added health benefits. Butyric acid is the preferred energy source for the colonocytes and has been shown to promote normal colonic epitheUal ceU differentiation. Butyric acid may inhibit colonic polyps and tumors. The relationships of intestinal microflora to health and disease have been reviewed (10). 

There is a complex interplay in the oncogenic virus-host relationship that complicates the study of these viruses as well as the assessment of the risk associated with working with them. Many of the tumor viruses appear to be benign in their natural host, but are oncogenic in a heterologous species. Some viruses may not cause a neoplasm or tumor in their natural host species under normal conditions, but, at times, stress or immuno-... 

Some synthetic macromolecules have shown intrinsic anticancer activity. Their mechanism of action is probably either the direct action upon the tumor cell, or the stimulation of the host s immune system [59] (Table 2). We do not exclude the use of such macromolecules as drug carriers in the future. However, the combination of a biologically active carrier with a biologically active drug makes the evaluation of the structure-property relationships more difficult. 

Kolarova, M., Host-tumor relationship XXXIII. Inhibitor of hyaluronidase in blood serum of cancer patients, Neoplasma, 22, 435, 1975. 

Cytokines may have growth inhibitory properties directly on cancer cells, cause tumor regression because of modification of the host tumor relationship, or enhance antitumor immune effects. They may also act as growth factors for malignant cells, and thus therapeutic strategies to inhibit their action become possible. They may also mediate paraneoplastic effects. 

Modification of Host-Tumor Relationships Local Spreads and Metastasis... 

It has been reported that tumor necrosis factor-a, a host-derived cytokine, stimulates egg-laying in S. mansoni worm pairs in vitro (52). This finding suggests that products of the host immune response to the parasite or products characteristic of the local environment within the host, can influence parasite reproduction. If parasites have receptors for host-derived cytokines, then the phylogenetic and functional relationship between the host cytokine network and that reported in invertebrates (53) becomes intriguing to explore in terms of parasite development. 

Nearly 100 years ago, Paul Ehrlich has proposed about the existence of certain relationship between tumor formation and host immune system [54,55]. However, this hypothesis has not been tested for a long time due to the limitations of technology in this field of research to test the theory experimentally [55]. 

SO elicited holds its secret occasional patients remain in complete remission and are cured for their natural life time. Other patients on the same therapy relapse on a scale rapidly and relendessly, or extremely slowly and living with their cancers transformed into a chronic ailment. The host-tumor relationship remains highly individualized, but the new treatment modalities shifted the balance to the favor of the vast majority of the patients. 

Indole 3-acetic acid (lAA) (17) also is found in certain bacteria. lAA is a virulence factor in the relationships of one bacterium. Pseudomonas syringae pv savastanoi, and its plant hosts, Nerium oleander (oleander, Apocynaceae) and Olea europaea (olive, Oleaceae). Virulence is assessed by the production of tumor-like outgrowths by the plants in response to secretion of phytohormones by the pathogen (Kosuge and Sanger, 1986). The bacterium produces lAA by conversion of L-tryptophan to indoleacetamide (18) and... 

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