Detrimental host effect

The underlying idea of the mechanism of action of the sulfonamides is quite general in the search for agents effective against pathogens but safe for humans find a clear biochemical difference between the host and its infectious agent and seek ways to exploit that difference to the benefit of the host and the detriment of the infectious agent. This is exactly what happens with the p-lactam antibiotics, to which we now turn. 

Some important bacterial toxins are produced in the host and have a detrimental effect on the host. For example, such toxins are synthesized by Clostridium tetani, common soil bacteria that enter the body largely through puncture wounds. 

Yarwood, in defining predisposition, wrote that if a chemical or physical treatment affects disease through its effect on the host, the condition is referred to as predisposition if it acts directly on the pathogen the condition is called activation. Predisposition may be both beneficial when disease on the weed host increases or detrimental when the chemical stimulates the weed host to produce a phytoalexin which in turn prevents disease (46). 

However, not all conditions that meet the technical definition of di.sease%re detrimental to plants. Nodules on the roots of peas and beans are caused by bacteria, and they do interrupt some of the normal plant functions, so they are a disease. Their net effect, however, is beneficial because these bacteria take nitrogen from the air and convert it into a form that plants can use. Similarly, the roots of almost all plants are infected with mycorrhizal fungi. Although they sap some food from plants, these beneficial fungi help their host plants garner nutrients from the soil by increasing the effective surface area of the root system. 

The properties of zeotype host-guest composites described above - i e, spatial organization, protection and stabilization of guest species - will become more important as molecules exhibit further properties that are essential for their use as materials. The well-developed synthetic methods for molecular compounds allow the preparation of designed molecular entities that possess predictable properties. However, no such thoroughly elaborated synthetic methods are available for the construction of organized arrays of functional molecules in their solid structures [36]. This is cumbersome since often the arrangement of the molecules in their solid compounds is detrimental to the effects (e g. non-linear optical, ferroelectric, electro-optical) that are to be exploited in materials. For example, many structures of molecules in the solid state are centrosymmetric. Also, molecular... 

A variety of helminths belonging to the class nematoda (roundworms), trema-toda (flatworms or flukes) and cestoda (tapeworms) are known to infect humans and domestic animals. The diseases caused by these worms are not only responsible for occasional deaths and wide range of health problems in man, but also exert detrimental effect on the nutritional and immune status of the host resulting in low resistance against other infections. The presence of helminth infections in livestock leads to decrease in output of animal products (milk, fat, butter, meat, eggs, wool and leather etc.) and has, therefore, strong socio-economic impact in countries with agro-and dairy-based industries [7]. 

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. 

In addition to their afore-mentioned beneficial effects, chemokines can participate in deleterious reactions and at times are pre-empted by pathogens to the detriment of the host. Chemokines may also have undesirable injurious side-effects by contributing to autoimmune diseases and participate in reperfusion injury. In addition, certain microbial organisms, including Plasmodium vivax and HIV-1, have been found to exploit chemokine receptors as sites for host cell entry (Fauci, 1996). Furthermore, a number of viral gene products are homologous to the chemokines or chemokine receptors and... 

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