Effect on host

Intracellular symbiosis is extremely widespread in invertebrates. For example, mutualistic symbioses with intracellular bacteria can be found in almost all animal phyla, including sponges, cnidaria, nematodes, anellids, mollusca and arthropoda. Buchner (1965) thoroughly reviews most information published on bacterial symbiosis in animals up to 1964. After this monumental work, various reviews on more specific subjects have been published (e.g. Baumann, 1998, and references therein) including some recent reviews on Wolbachia (O Neill et al., 1997 Werren, 1997). In most of these papers, the term symbiosis is apparently used with a broad meaning the intracellular bacterium is usually referred to as an endosymbiont even in the absence of data on effects on host fitness. Here only key points on intracellular symbiosis and Wolbachia will be summarized, so as to put the information available on symbiosis in filarial nematodes into a broader context. 

Antibiotic curing experiments provide a powerful approach in investigating endosymbiont effects on host biology and have been widely used in work on arthropod Wolbachia. A number of such experiments have been inadvertently conducted on filarial worms, in the course of testing... 

At least some of the cannabinoid-induced modulation of immune cells, and effects on host resistance to infection, are mediated directly by binding of cannabinoids to CBRs, particularly CBR2. Host immunity to microbes, however, involves many cell types, both immune and non-immune, as well as soluble factors including cytokines, chemokines, neurocytokines, and hormones related to the HP axis. It is therefore likely that a variety of cellular and molecular mechanisms whereby cannabinoids, including THC, affect immune function. 

Zhang, X., Gramlich, G., Wang, X. and Nau, W.M. (2002) A joint structural, kinetic, and thermodynamic investigation of substituent effects on host-guest complexation of bicyclic azoalkanes by -cyclodextrin./. Am. Chem. Soc., 124 (2), 254-263. 

FINCH, S., Volatile plant chemicals and their effect on host plant finding by the cabbage root fly. Entomol. Exp. Appl., 1978,24, 150-159. 

Brandes, B., Godbold, D. L., Kuhn, A. J. Jentschke, G. (1998). Nitrogen and phosphorus acquisition by the mycelium of the ectomycorrhizal fungus Paxillus involutus and its effect on host nutrition. New Phytologist, 140, 735 3. 

Solvent Effects on Host/Guest Complexation Equilibria [294-299]... 

In addition to exerting a beneficial effect on host health, prebiotics can be incorporated into foods as they possess various physiochemical properties. Pla)me and Crittenden [48] identified desirable attributes for these oligosaccharides (O Table 6). Currently the Japanese are the market leaders as regards prebiotic food stuffs, but America and Europe are slowly catching up. 

General effect on host Little not generally lethal Will usually kill the host if not treated... 

The biological activity of polycarboxylates, polynucleotides and small molecular weight interferon inducers (e.g tilorone) is not restricted to interferon production. In vivo, they exert many other effects on host defense mechanisms, including an increase of the body temperature (pyrogenicity), a stimulation of humoral and cellular immune responses (immuno-adjuvant effect), and an enhancement of the reticulo-endothelial cell activity (phagocytosis) (Fig. 8). 

In vivo, interferon inducers exert a wide variety of effects on host defense mechanisms interferon production, pyrogenicity, stimulation of cellular and humoral immunity and stimulation of reticulo-endothelial activity. It is not surprising, therefore, that interferon inducers increase the host s resistance to both viral and non-viral (bacterial, fungal, protozoal) infections and tumor growth. A major obstacle confronting the clinical usefulness of interferon inducers is their toxicity. Are interferon induction and toxicity necessarily coupled or can they be disconnected Preliminary evidence suggests that, at least with poly(I) poly(C), toxicity and activity could be uncoupled. 

Some antibiotics are active against both bacterial and mammalian cells. One example is chloramphenicol, which inhibits peptidyltransferase in both bacterial and mitochondrial ribosomes, although eukaryotic cytoplasmic ribosomes are unaffected. Such a drug may be clinically useful if a concentration range can be maintained in the patient in which the antibacterial action is substantial but toxic effects on host cells are minimal. However, because of the potential for toxicity, such antibiotics are used only in serious infections when other drugs fail. 

The fluid and protein shift into the abdomen (called third-spacing) may be so dramatic that circulating blood volume is decreased, which causes decreased cardiac output and hypovolemic shock. Accompanying fever, vomiting, or diarrhea may worsen the fluid imbalance. A reflex sympathetic response, manifested by sweating, tachycardia, and vasoconstriction, may be evident. With an inflamed peritoneum, bacteria and endotoxins are absorbed easily into the bloodstream (translocation), and this may result in septic shock. Other foreign substances present in the peritoneal cavity potentiate peritonitis. These adjuvants, notably feces, dead tissues, barium, mucus, bile, and blood, have detrimental effects on host defense mechanisms, particularly on bacterial phagocytosis. 

Selective toxicity is the ability of an antimicrobial agent to act on an infecting organism without toxic effects on host cells. The extent of selective toxicity depends on its mechanisms of action, of which there are five basic categories, as shown in Table V-l-1. 

In most plant-microorganism relationships, there are costs and few benefits for the host plants in the interaction. However, infections by Balansia species can yield benefits in addition to any adverse effects on hosts. For instance,... 

Recent studies have revealed that the human tumor viruses EBV, HHV-8, human papillomavirus, HBV, HCV, and HTLV-1 express proteins that are targeted to the mitochondria (8). Because the mitochondria play a critical role in energy production, cell death, calcium homeostasis, and redox balance, these proteins have profound effects on host cell physiology. Further study of these proteins and their interactions with mitochondria will aid in the understanding the mechanisms of viral replication and tumorigenesis and could reveal important new targets for anti-tumor therapy. 

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