Inhibitors toxicity

The first phase, A, is called the lag phase. It will be short if the culture medium is adequate, i.e. not necessarily minimal, and is at the optimum temperature for growth. It may be longer if the medium is minimal or has to warm up to the optimum growth temperature, and prolonged if toxic substances are present other things being equal, there is a relationship between the duration of the lag phase and the amount of the toxic inhibitor. 

Let consider model of dynamics of populations in the view of shortened chain (9) of two-stages - growth and division in the presence of two toxicants (inhibitors of growth) Xi and... 

Non-toxic inhibitors of radical processes - antioxidants exhibit a wide gamut of biological activity. 

Leflunomide is a potent noncyto toxic inhibitor of the proliferation of stimulated B and T-lymphocytes, which depend on de novo pyrimidine synthesis to fulfill their metabolic needs (Breedveld and Dayer, 2000 Herrmann et al., 2000). This antiproliferative effect can be antagonized in vitro by the addition of uridine or cytidine to the cell culture medium, underscoring the significance of this mechanism of action (Cao et al., 1995 Williamson et al., 1995 Zielinski et al.,... 

The bis (o, rn and p-nitrophenyOphosphate triesters of AZT have been found to be potent and non-toxic inhibitors of HIV in TK+ strains, but display comparably poor activity in TK strains to that of AZT. Thus their mode of action differs from that of the phosphoramidates mentioned earlier in that they act as prodrugs of the free nucleoside rather than as nucleotide delivery forms. A study of several aryl phosphotriesters of AZT has revealed that the anti-HIV activity is inversely related to the pKa of the respective phenol and probably therefore related to its leaving group ability. It has been shown that the triester is hydroly.sed in human plasma to the corresponding diester which is probably dephosphorylated extracellularly and thus enters the cell as the free nucleoside by diffusion. 

We treated a PNP-deficient patient, born in January 1975, (8), with erythrocyte transfusions for more than 5 years. This regimen has resulted in a partial restoration of in vitro T cell function. Orally, and lateron intravenously administered dCyd had no additional benificial effect at all(6). The still existing T cell deficiency is reflected in the clinical condition of the patient she still shows a vulnerability to infection(9). We therefore have treated the patient again with dCyd, this time in combination with tetrahydro-uridine (THU), a potent non-toxic inhibitor of (deoxy)cytidine deaminase. We present here the metabolic and immunological results during this treatment. 

Results were obtained for chemicals with phosphono and/or carboxyl groups various types were used in order to replace very effective but toxic inhibitors, and to decrease the phosphorus content in the inhibitor. Positive correlation was found between the number of substituents with negative charge, especially with phosphono groups. As these compounds are derivatives of natural amino acids, their catabolism results in nontoxic chemicals, and the ratio of the phosphorus is lower than in the chemicals used as industrial corrosion inhibitors. Electrode impedance measurements pointed to the importance of time in the formation of a protective layer on the metal surface. 

Toxicity issues will continue to be some of the most important aspects of corrosion inhibitor technology, and meeting the demands for less toxic inhibitors will consume a large portion of the funds available to develop new formulations. Other issues such as flash point and presence of heavy metals will limit the palette available to the inhibitor formulator. A comprehensive review of "green" inhibitor technology was presented at the 2000 Ferrara, Italy inhibitor conference. ... 

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