Primary toxic solution

In most of our experiments, guinea pigs were sensitized by the use of a primary toxic solution (DNCB 1% in acetone). 

As in a certain number of our experiments, some investigators used primary toxic solutions of DNCB others employed primary non-toxic solutions of DNCB, as we did in some of our experiments. There are many technical differences (concentration, number of applications) in addition to numerous variations in the results obtained by experimentation on guinea pigs in different laboratories as well as in the same laboratory. 

In unsensitized guinea pigs, a primary toxic solution of 1% and 2% DNCB in acetone is applied on the acanthosed flank as well as on the normal flank. 

These facts prompted us to ask Can the young guinea pig be sensitized as easily as the adult guinea pig We sensitized new-born guinea pigs (2 days old and weighing between 60 and 80 gr.) by the epicutaneous application of a primary toxic solution of 1% DNCB in acetone, performed in the same manner as for adult guinea... 

Free cyanide is the primary toxic agent in the aquatic environment. Free cyanide refers to the sum of molecular HCN and the cyanide anion (CN ), regardless of origin. In aqueous solution with pH 9.2 and lower, the majority of the free cyanide is in the form of molecular HCN. The chemical names for HCN include hydrogen cyanide, hydrocyanic acid, cyanohydric acid, and prussic acid. 

Capsules/Tablets/Oral solution-The primary toxicity of ribavirin is hemolytic anemia, which occurs within 1 to 2 weeks of initiation of therapy. 

An important harmful effect of metals at the cellular level is the alteration of the plasma membrane permeability, leading to leakage of ions like potassium and other solutes (Passow and Rothstein, 1960 Wainwright and Woolhouse, 1978 De Filippis, 1979 De Vos et al., 1988, 1991). After supply of copper ions Ohsumi et al. (1988) demonstrated for yeast cells and De Vos et al. (1989) for root cells of Silene cucubalus that the permeability barrier (controlled by means of potassium leakage) of the plasma membrane was almost immediately lost. Oshumi et al. (1988) also reported a quick release of amino acids, especially glutamate and aspartate. After McBrien and Hassall (1965) and Overnell (1975), who studied potassium release from algal cells, the increased permeability of the plasma membrane may be considered to constitute the primary toxic effect of copper. 

We would like to insist, as have Macher and Sennlaub (1963), that the main source of error which leads to misinterpretation lies in the very small difference between the minimum concentration of the solution used in the patch test for the specific reaction of sensitization and the minimum concentration producing a primary toxic effect. 

Using a primary non toxic solution of DNCB for sensitization, de Weck and Brun (1956) obtained negative results in summer but their results were positive in winter. These experiments should be repeated. 

After 8 daily applications we observed a clear sensitization in some guinea pigs, demonstrated by the patch test on the flank (out of 10 tests, 5 were positive). After 20 to 40 applications on a single nipple, the patch tests on the flanks are positive in almost all of the guinea pigs. Therefore, a general sensitization occurs even though the multiple applications are performed on a very small surface and with a primary non-toxic solution of DNCB (Table 1). 

By intraganglional administration. Seeberg (1951) sensitized a certain number of animals but the concentration of the solution of DNCB used in this test is high (1 %), see p. 7 primary toxic reaction. 

In our experiments on the primary toxic reaction, we used a 1% solution of DNCB in acetone, which gives a well defined erythematous reaction after 14 hours (patch test for a primary toxic reaction). 

In applying a 1 % solution of DNCB on the flank without acanthosis, the primary toxic lesions already described are observed after 24 hours (sub-epidermal bullae, necrosis of the epidermis, infiltration), whereas on the flank with acanthosis there are practically no lesions (Fig. 4a and b). 

If a 1% solution of DNCB is applied on the nipple with acanthosis, there are no lesions (excision 24 hours after application). However if the same solution is applied on a nipple without acanthosis, the usual primary toxic lesions are observed (necrosis of the epidermis). 

In conclusion acanthosis protects against the primary toxic action of DNCB but only to a certain extent, for if the concentration of the solution is increased to 2%, the protection is greatly reduced. 

According to most authors, and our studies, a 0.1% primary non-toxic solution of DNCB in acetone causes no macroscopically visible reaction and no histological alterations on the flank and the nipple of guinea pigs. 

According to results obtained by various authors and ourselves, the concentrations sufficient to give an interpretable patch test, but hardly ever a primary toxic reaction, are for DNCB solutions ... 

As for the primary toxic reaction, not only the concentration of the allergen, but also the solvent, must be taken into consideration for the test. Solutions of DNCB diluted in oil are less potent than alcoholic or acetonic solutions. 

The metallic salts of trifluoromethanesulfonic acid can be prepared by reaction of the acid with the corresponding hydroxide or carbonate or by reaction of sulfonyl fluoride with the corresponding hydroxide. The salts are hydroscopic but can be dehydrated at 100°C under vacuum. The sodium salt has a melting point of 248°C and decomposes at 425°C. The lithium salt of trifluoromethanesulfonic acid [33454-82-9] CF SO Li, commonly called lithium triflate, is used as a battery electrolyte in primary lithium batteries because solutions of it exhibit high electrical conductivity, and because of the compound s low toxicity and excellent chemical stabiUty. It melts at 423°C and decomposes at 430°C. It is quite soluble in polar organic solvents and water. Table 2 shows the electrical conductivities of lithium triflate in comparison with other lithium electrolytes which are much more toxic (24). 

Coatings, Paints, and Pigments. Various slightly soluble molybdates, such as those of zinc, calcium, and strontium, provide long-term corrosion control as undercoatings on ferrous metals (90—92). The mechanism of action presumably involves the slow release of molybdate ion, which forms an insoluble ferric molybdate protective layer. This layer is insoluble in neutral or basic solution. A primary impetus for the use of molybdenum, generally in place of chromium, is the lower toxicity of the molybdenum compound. 

Melamine ia a skin test on rabbits produced neither local irritation nor systemic toxicity. As a 10% solution ia methylceUulose, it caused no irritation ia the eyes of rabbits. Human subjects were given patch tests with melamine. No evidence of either primary irritation or sensitization was found. Such results suggest that melamine crystal may be handled ia ordinary iadustrial use without special hygienic precautions. 

Purification as their N-acetyl derivatives is satisfactory for primary, and to a limited extent secondary, amines. The base is refluxed with slightly more than one equivalent of acetic anhydride for half to one hour, cooled and poured into ice-cold water. The insoluble derivative is filtered off, dried, and recrystallised from water, ethanol, aqueous ethanol or benzene (CAUTION toxic ). The derivative can be hydrolysed to the parent amine by refluxing with 70% sulfuric acid for a half to one hour. The solution is cooled, poured onto ice, and made alkaline. The amine is steam distilled or extracted as above. Alkaline hydrolysis is very slow. 

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