Toxicity, organ specific effects

Measurement of exoenzymatic activities is potentially useful in detecting the effects of toxicants on heterotrophic biofilm communities. Sensitivity and direct relationship with organic matter use and, therefore, microbial growth make extracellular enzyme activities a relevant tool to assess the toxicity of specific compounds. Use of novel approaches that combine enzymatic and microscopic tools (e.g. ELF-phosphatase) may be extremely useful to detect anomalies at the sub-cellular scale. 

For most types of toxic effects (e.g., organ-specific, neurological, immunological, non-genotoxic carcinogenicity, reproductive, developmental), it is generally considered that there is a dose or... 

As this enzyme does not exist in mammals and man, potential specific inhibitors could serve as non-toxic, no side effect antibiotics against gram-negative pathogenic organisms imder consideration. 

The disposition or localization, and in some cases metabolism, of foreign compounds may be dependent upon the characteristics of a particular tissue or organ, which may in turn affect the toxicity. There are many examples of organotropy in toxicology, but the mechanisms underlying such organ-specific toxic effects are often unknown. 

A general rule for concentration techniques in their transit function is that selectivity of the transfer of a specific effect facilitates the identification of responsible compounds. A so-called general concentration procedure with an optimal recovery of all organic compounds turns out to be a utopian scheme in many cases. The interface is too broad and too extensive to transmit clearly distinctive signals. Such a broad interface, capable of transmitting simultaneously many different signals, is of use when toxicities of different environmental systems have to be compared with each other. 

Because of the pressing contemporary need to assess an ever-growing number of chemicals and complex environmental samples, the development and use of small-scale toxicity tests (also called micro-scale toxicity tests or microbiotests ) have increased because of their attractive features. Simply defined as a test involving the exposure of a unicellular or small multicellular organism to a liquid or solid sample in order to measure a specific effect , small-scale tests are generally simple to execute and characterized by traits which can include small sample volume requirements, rapid turnaround time to results, enhanced sample throughput and hence cost-effectiveness (Blaise et al., 1998a). 

Treatment in an investigation or study that duplicates all the conditions and factors that might affect the results of the investigation, except the specific condition that is being studied. In an aquatic toxicity test, the control must duplicate all the conditions of the exposure treatment(s), but must contain no added test material or substance. The control is used to determine the absence of measurable toxicity due to basic test conditions (e.g., temperature, health of test organisms, or effects due to their handling or manipulation). Volume 1(2), Volume 2(5). 

A number of zinc compounds with organic constituents (e.g., zinc salts of organic acids) have therapeutic uses. These include antidandruff zinc pyridinethione, antifungal zinc undecylenate used to treat athlete s foot, zinc stearate and palmitate (zinc soap), and antibacterial zinc bacitracin. Zinc naphthenate is used as a low-toxicity wood preservative, and zinc phenolsulfonate has insecticidal properties and was once used as an intestinal antiseptic. The inhalation of zinc soaps by infants has been known to cause acute fatal pneumonitis characterized by lung lesions similar to, but more serious than, those caused by talc. Zinc pyridine thione (zinc 2-pyridinethiol-l-oxide) has been shown to cause retinal detachment and blindness in dogs this is an apparently species-specific effect because laboratory tests at the same and even much higher dosages in monkeys and rodents do not show the same effect. 

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