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Masking the taste of the conditioned taste aversion agent levamisole using an ion-exchange resin, for practical application in wildlife management.

For a conditioned taste aversion (CTA) agent to be successful in wildlife management applications, the compound must not be detectable by the animal. Levamisole is an effective CTA agent when administered by oral intubation, but it is readily detected by a number of species when mixed directly in food. This paper describes the development of an ion-exchange resin complex (resinate) to mask the taste of levamisole. Two different resins were evaluated, Amberlite IRP-64 and Amberlite IRP-69, and release studies indicated that the resinate formed using IRP-64 resin would be most suitable for use in wildlife management. Although it contained a relatively low loading of levamisole (77 g kg(-1)), the results indicated that the IRP-64 resinate should be stable in the mouth and release the levamisole quickly in the acid environment of the stomach (93% of levamisole was released into 0.1 M HCl in 5 min). In a bioassay using laboratory rats (Rattus norvegicus Berk), we showed that the taste of levamisole was successfully masked in a biscuit bait using the IRP-64 resinate and that a CTA was generated to untreated bait. The use of ion-exchange resins is a new approach in the taste-masking of CTA agents and could be applied to other wildlife management applications.

Animals↗

Cytotoxicity of a new toothpaste based on an ion exchange resin mixture.

PURPOSE: To evaluate the effects for cytotoxicity of two dentifrices: a toothpaste commercially available (Crest Extra-Whitening toothpaste) and a new experimental toothpaste based on a mixture of ion-exchange resins (named NMTD) that supplies calcium, fluoride, phosphate and zinc ions. METHODS: Cultures of mouse fibroblasts cells L929 were used in a MTT assay for in vitro cytotoxicity of the dentifrices. Cells were cultured in Eagle's minimal essential medium supplemented with 10% fetal bovine serum. Cultures were incubated at 37 degrees C in a humidified atmosphere of 5% CO2 and collected by tripsinization (0.05% trypsin/0.5mM EDTA). A 96-well microplate method was employed for the MTT colorimetric assay. Positive control consisted of 10 microl of phenol in 5 ml of 6% media, a dose that produces zero percent cell survival. Negative control was prepared by adding 0.5 ml of HBSS to 4.5 ml of 6% media. The plates were incubated for 24 and 48 hours at 37 degrees C in a 5% CO2 atmosphere. RESULTS: Means and standard deviations of absorbance values for each group and percentage inhibitory dosage (%ID) for each test material were calculated. None of the dentifrices resulted in a percentage of inhibition higher than 50% and did not observe marked increases in cytotoxicity with time of incubation. The positive control gave almost zero percent cell survival, whereas the negative control gave a hundred percent cell survival. Analysis of the results indicated that test dentifrice dose had no significant effect towards the cell viability (P<0.05).

Animals↗

Ion-exchange resins in the isolation of nitrogen compounds from petroleum residues.

In this work, preparative liquid chromatography was used for the separation of the nitrogen compounds in a sample of heavy gas oil from a Brazilian petroleum. Initially it took place a pre-fractionation by neutral aluminium oxide and the compounds were separated in different classes such as: hydrocarbons, resins (compounds of low molecular mass and intermediate polarity) and asphalthenes (polar compounds with high molecular mass). A comparison of the fraction of resins was performed by re-fractionating with modified silica (with potassium hydroxide and hydrochloric acid), or with ion exchange resins (Amberlyst A-27 and A-15), being isolated the basic and neutral compounds, that were analyzed by GC-MS in the scan and selected ion monitoring modes. Quinolines, benzoquinolines, tetrahydroquinolines were found in the basic fraction and carbazoles derivatives were found in the neutral fraction.

Gas Chromatography-Mass Spectrometry↗