Mixture Of Chloramphenicol Research Articles

Застосування нового УЕРХ-МС/МС мультиметоду визначення залишкових кількостей антимікробних препаратів для контролю безпеки меду

У статті представлено результати впровадження розробленого УЕРХ-МС/МС мультиметоду для кількісного визначення залишків різних груп антимікробних препаратів у меді. Основною перевагою цього методу є простота, експресність та економічна ефективність, оскільки аналіз проводиться за однієї пробопідготовки. Методику апробовано при аналізі нативно контамінованих та фортифікованих зразків меду, а також при проведенні міжлабораторних досліджень. За період 2018-2019 років з використанням розробленого нами мультиметоду було проаналізовано 809 експортних партій меду за показниками безпеки, а також 946 зразків – для вхідного контролю сировини. Найчастіше проводились дослідження меду на вміст залишків метронідазолу та хлорамфеніколу, а саме – 68 % та 52 % аналізованих зразків, відповідно. Виявлено, що серед зразків вхідного контролю меду 297 містили цільові аналіти на рівні, вищому за межу виявлення методу. Це чітко свідчить про непоодинокі факти використання українськими бджолярами незареєстрованих антимікробних препаратів для лікування та/або профілактики хвороб бджіл. Отримані дані не претендують на високу репрезентативність, оскільки базуються на аналізі зразків меду безпосередньо від замовників, а не отримані внаслідок моніторингу шляхом випадкового вибору проб.

Effect of organic toxicants on the activity of denitrifying granular sludge

Denitrification plays a key role in the biological nitrogen removal from the wastewater using granular sludge as the integral part of a high-rate denitrification technology. It is helpful to evaluate the effect of typical organic toxicants on the activity of denitrifying granular sludge for the application of denitrification technology. In this study, four typical organic toxicants, namely, penicillin, chloramphenicol, 2,4-dinitrophenol and polymyxin B sulphate were used to assess the effect of organic toxicants on the activity of denitrifying granular sludge. The results of individual toxicity indicated that penicillin, chloramphenicol and 2,4-dinitrophenol had significant inhibition, whose half-inhibitory concentrations were 0.534, 0.162 and 0.474 g/L with respective inhibitory magnitudes of 90.79%/(g/L), 282.5%/(g/L) and 138.83%/(g/L). Polymyxin B sulphate showed no significant inhibition. The results of combined toxicity indicated that the binary mixture of penicillin and chloramphenicol had an antagonistic effect, both the binary mixture of penicillin and 2,4-dinitrophenol and the binary mixture of chloramphenicol and 2,4-dinitrophenol had additive effects. The ternary mixture of penicillin, chloramphenicol and 2,4-dinitrophenol had a partial additive effect.

Evidence for the biological turnover of thiols in anoxic marine sediments

The concentrations of methanethiol (MSH) and 3-mercaptopropionate (3-MPA) increased for a period of up to 24 h in fresh slurries of anoxic Biscayne Bay sediments. Other endogenous thiols such as glutathione (GSH) deceased immediately after slurry preparation or were not detectable at all. The maximum concentrations reached by 3-MPA and MSH were sometimes as high as 1 μM, but were usually in the 100 to 300 nM range. After the initial increases, the concentrations of these thiols decreased rapidly to nearly constant levels of ∼20 nM for MSH and < 1nM for 3-MPA. In pre-incubated slurries, which had constant levels of thiols, the addition of microbial inhibitors including tungstate, molybdate, chloroform, and a mixture of chloramphenicol plus tetracycline caused MSH and 3-MPA to accumulate steadily. In the presence of inhibitors, accumulation rates of MSH ranged from 18 to 730 nM · d-1 and those of 3-MPA ranged from 0 to 185 nM · d-1. Tungstate and chloroform generally gave the highest accumulation rates, while molybdate gave the lowest, possibly due to its complexation with sulfhydryl compounds. BES (2-Bromoethanesulfonate) was also tested for its effects, but no 3-MPA and only trace amounts (19 nM · d-1) of MSH accumulated with this treatment. However, additions of BES (10 mM) to sulfidic sediments caused significant (∼8 μM · d-1) production of 2-mercaptoethanesulfonate (HS-CoM). Formation of HS-CoM was abiotic and was due to sulfide attack on the bromine atom in BES. The accumulations of 3-MPA and MSH in the presence of several different microbial inhibitors, suggests that these thiols may turn over in anoxic sediments. The relatively low concentrations of thiols observed in pore water profiles may be due to continuous microbial removal of these compounds. Much larger amounts of thiols were associated with sediment particles than present in the pore water. Evidence is presented which suggests that bound thiols may be exchangeable with the porewater, and therefore potentially available for microbial consumption.

Sulfur-Containing Amino Acids as Precursors of Thiols in Anoxic Coastal Sediments

Sulfur-containing amino acids were examined as precursors for thiols in anoxic coastal sediments. Substrates (10 to 100 muM) were anaerobically incubated with sediment slurries; thiols were assayed as isoindole derivatives by high-performance liquid chromatography; and microbial transformations of thiols, in contrast to their chemical binding by sediment particles, were identified by inhibition with a mixture of chloramphenicol and tetracycline. Methionine and homocysteine were transformed to methanethiol and 3-mercaptopropionate (3-MPA); methionine stimulated mainly methanethiol production, whereas homocysteine generated more 3-MPA than methanethiol. 2-Keto-4-methiolbutyrate yielded results similar to those with methionine, indicating that demethiolation yields methanethiol at the keto-acid level. Glutathione gave rise to cysteine, which was further transformed to 3-mercaptopyruvate and thence to mercaptoacetate and mercaptoethanol. Mercaptoethanol was oxidized to mercaptoacetate, which was biologically consumed. In conclusion, sulfurcontaining amino acids contribute to the range of thiols that occur in anoxic coastal sediments. New metabolic and environmental transformations were identified: the production of 3-MPA as a metabolite of methionine and the transformation of mercaptopyruvate to mercaptoethanol and mercaptoacetate.

Prophylactic Antibiotics in Cataract Surgery

The value of preoperative cultures, sensitivity tests and prophylactic preoperative antibiotic treatment was evaluated in a group of senile, uncomplicated lens extractions. Sulfacetamide or a mixture of chloramphenicol and polymixin were applied preoperatively for 1 week and an injection of penicillin and streptomycin was given postoperatively. A control group of 140 cases without treatment was also studied. No postoperative infections developed in either group. The number of pathogenic cultures was significantly smaller in the treated group as compared with the untreated one; the mixture of chloramphenicol and polymixin B sulfate was found to be superior to sulfacetamide, different clinical data was compared in the two groups. No postoperative infections developed in either group.

Determination of Chloramphenicol by Gas-Liquid Chromatography

Convenient gas-liquid chromatographic methods for the analysis of chloramphenicols have been described. A mixture of chloramphenicol and its acetates was completely separated and identified. For estimation, pharmaceuticals or plasma was extracted with appropriate solvent and chromatographed directly without extensive treatment utilizing hydrogen flame or electron capture detector system, respectively. The methods have speed, simplicity, and accuracy.