HPLC identification of isoniazid residues in bovine milk

Antituberculosis drug isoniazid degraded by electro-Fenton and photoelectro-Fenton processes using a boron-doped diamond anode and a carbon-PTFE air-diffusion cathode

Solutions with 0.65 mM of the antituberculosis drug isoniazid (INH) in 0.050 M Na₂SO₄ at pH 3.0 were treated by electro-Fenton (EF) and UVA photoelectro-Fenton (PEF) processes using a cell with a BDD anode and a carbon-PTFE air-diffusion cathode. The influence of current density on degradation, mineralization rate, and current efficiency has been thoroughly evaluated in EF. The effect of the metallic catalyst (Fe²⁺ or Fe³⁺) and the formation of products like short-chain linear aliphatic carboxylic acids were assessed in PEF. Two consecutive pseudo-first-order kinetic regions were found using Fe²⁺ as catalyst. In the first region, at short time, the drug was rapidly oxidized by ^●OH, whereas in the second region, at longer time, a resulting Fe(III)-INH complex was much more slowly removed by oxidants. INH disappeared completely at 300 min by EF, attaining 88 and 94% mineralization at 66.6 and 100 mA cm^-2, respectively. Isonicotinamide and its hydroxylated derivative were identified as aromatic products of INH by GC-MS and oxalic, oxamic, and formic acids were quantified by ion-exclusion HPLC. The PEF treatment of a real wastewater polluted with the drug led to slower INH and TOC abatements because of the parallel destruction of its natural organic matter content.

Isoniazid treatment of Mycobacterium bovis in cattle as a model for human tuberculosis

Cattle infected with Mycobacterium bovis spoligotype 9 were treated with Isoniazid (INH) from three to 14 weeks post infection, rested for fourweeks to allow INH depletion and then challenged with M. bovis spoligotype 35. Post mortem examination (PME) 35 weeks after the initial infection showed partial protection against infectious challenge following INH-attenuated infection compared with the spoligotype 35 challenge controls. Antigen-specific IFN-gamma responses decreased over time with INH therapy, following a similar pattern to that observed in the treatment of M. tuberculosis infection in humans. Following cessation of therapy, specific IFN-gamma responses increased more strongly in those calves that were visibly lesioned at PME. IFN-gamma responses were also used to identify two antigens, TB10.4 and Acr2, that induced anamnestic responses in INH-treated, re-challenged calves, suggesting a role for both antigens in protective immunity. Specific IL-10 responses were observed in all calves following treatment with INH suggesting a role for IL-10 in the resolution of infection.

Is interleukin-4delta3 splice variant expression in bovine tuberculosis a marker of protective immunity?

Splice variants of the interleukin-4 (IL-4) cytokine gene have been described for humans, mice, and cattle. IL-4 splice variants have been shown to inhibit IL-4-mediated cellular responses and thus act as IL-4 antagonists. Recent work has highlighted the possibility of a correlation between IL-4 splice variants and protection against clinical tuberculosis. In this study we investigated the potential role of IL-4 splice variants IL-4delta2 and IL-4delta3 in cattle with bovine tuberculosis, using quantitative real-time reverse transcription-PCR. For this analysis we used naturally exposed tuberculin skin test-positive field reactor cattle, uninfected control cattle, and cattle from two experimental models of protective immunity against Mycobacterium bovis: (i) vaccination with M. bovis BCG and challenge with virulent M. bovis and (ii) infection with M. bovis and treatment with isoniazid (INH) prior to rechallenge. The cytokine levels of field reactor cattle were compared to the levels of uninfected controls, while in kinetic studies of BCG vaccination and INH treatment we compared pre-experimental values with sequential samples for each individual animal. The data revealed a significant increase in IL-4delta3 mRNA expression in field reactor cattle, which had no visible pathology compared to cattle with gross pathology typical of bovine tuberculosis. Increased IL-4delta3 expression in both cattle models of protective immunity (BCG vaccination and INH treatment) was transient over time, reaching significance in the INH treatment model. Our results support the hypothesis that IL-4delta3 is involved in protective immunity against M. bovis infection in cattle and are in accordance with clinical studies that have suggested a role for IL-4 splice variants in protective immunity in tuberculosis.