Removal of oxytetracycline and determining its biosorption properties on aerobic granular sludge

This study investigates biosorption of Oxytetracycline, a broad-spectrum antibiotic, using aerobic granular sludge as an adsorbent in aqueous solutions. A sequencing batch reactor fed by a synthetic wastewater was operated to create aerobic granular sludge. Primarily, the pore structure and surface area of granular sludge, the chemical structure and the molecular sizes of the pharmaceutical, operating conditions, such as pH, stirring rate, initial concentration of Oxytetracycline, during adsorption process was verified. Subsequently, thermodynamic and kinetic aspects of the adsorption were examined and adsorption isotherm studies were carried out. It was shown that the aerobic granular sludge was a good alternative for biosorption of this pharmaceutical. The pharmaceutical was adsorbed better at pH values of 6–8. The adsorption efficiency increased with rising ionic strength. Also, it was seen that the adsorption process was an exothermic process in terms of thermodynamics. The adsorption can be well explained by Langmuir isotherm model.     

土霉素氧化锌膏治疗干槽症的临床研究

目的 观察土霉素氧化锌膏治疗干槽症的临床疗效.方法 将248例干槽症患者随机分为两组,局麻行牙槽窝刮治后,治疗组(136例)在牙槽窝内置土霉素氧化锌膏,对照组(112例)在牙槽窝置滴入丁香油的碘仿纱条.观察1～5 d,比较两组的疗效.结果 治疗组136例中,完全止痛40例,基本止痛66例,疼痛减轻30例,总有效率为100％.对照组112例中,完全止痛20例,基本止痛40例,疼痛减轻20例,无效32例,总有效率71.3％.两组总有效率比较有统计学意义(x2=44.61,P＜0.01).结论 土霉素氧化锌膏是治疗干槽症的有效方法之一.     

药物性胆管消失综合征2例

临床约10%的急性肝炎由药物性肝损伤(DILI)所引起。而药物或其代谢产物以胆管上皮为损伤靶点可诱发胆管消失综合征(VBDS)。VBDS在临床诊疗中时常被忽视或与其他胆管性疾病相混淆。因此,需要临床医生予以重视并加以鉴别。现报告2例VBDS典型病例。     

高效液相色谱法测定土霉素片的含量

目的建立土霉素片的含量测定方法。方法高效液相色谱法。采用Luna-C18色谱柱,以0.05 mol/L草酸铵溶液-二甲基甲酰胺-0.2 mol/L磷酸氢二铵(70∶25∶5)为流动相,用紫外检测器在282 nm波长处检测。结果土霉素片浓度在0.01¹ mg/mL范围内与峰面积线性关系良好(r=0.9990),平均回收率为100.1%。结论高效液相色谱法快速、简便、准确,可用于土霉素片的含量测定。     

龟裂链霉菌工业菌中zwf1基因的阻断对土霉素生物合成影响

目的运用代谢工程手段对龟裂链霉菌工业菌(Industrial Streptomyces rimosus,SRI)进行基因改造,提高土霉素(oxytetracycline,OTC)产量。方法利用pKC1139质粒阻断SRI基因组中葡萄糖-6-磷酸脱氢酶(glucose-6-phosphate dehydrogenase)编码基因zwf1。结果筛选得到一株OTC高产突变株,将突变株与原始菌株进行发酵,发现OTC产量比原始菌株提高了36.2%。结论 SRI基因组中zwf1基因的缺失使细胞合成土霉素的能力增强;龟裂链霉菌中初级代谢关键基因调控会影响次级代谢。     

Avoidance behavior of Eisenia fetida in oxytetracycline- and heavy metal-contaminated soils

To determine the behavior of oxytetracycline (OTC) and heavy metals in soil, this study assessed the pollutant-induced avoidance behavior of earthworms (E. fetida) exposed to zinc (Zn²⁺), lead (Pb²⁺), and OTC in soil. The results showed a clear avoidance response within 48 h of exposure to the highest concentrations of pollutants. Moreover, E. fetida was shown to be more sensitive to Zn²⁺ than to Pb²⁺ and OTC. Compared with OTC alone, the net response of earthworms increased in the OTC-Zn²⁺ and OTC-Pb²⁺ combined treatments, indicating a synergistic effect. Moreover, the net response (NR) of the earthworms was higher for OTC-Zn²⁺ than it was for OTC-Pb²⁺, possibly reflecting the differences in essential characteristics of Zn and Pb.     

铜和土霉素复合暴露对玉米幼苗生长发育的影响

目的探讨铜和土霉素复合暴露对玉米幼苗生长发育的影响。方法观察铜(Cu~(2+))和土霉素(OTC)单一暴露及Cu~(2+)+OTC复合暴露对其发芽、总根长、叶片抗氧化酶和丙二醛含量的影响。结果 OTC、Cu~(2+)单一暴露、Cu~(2+)+OTC复合暴露对玉米种子发芽率的影响无统计学意义(P0.05)。与对照组相比,Cu~(2+)(20、30 mg/L)单一暴露组总根长在8 h显著减低,随着生长时间的延续,Cu~(2+)(20、30和40 mg/L)单一暴露组总根长在96 h明显减低,差异有统计学意义(P0.05);与对照组相比,Cu~(2+)+OTC(30、40 mg/L)组处理8 h玉米幼苗根系总根长缩短,随着玉米幼苗的生长,在24 h~96 h Cu~(2+)+OTC(10~40 mg/L)复合暴露组玉米幼苗根系总根长缩短,差异有统计学意义(P0.05)。Cu~(2+)+OTC复合暴露与Cu~(2+)、OTC单一暴露对玉米幼苗叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)的活力没有明显影响(P0.05)。与对照组相比,40 mg/L Cu~(2+)单一暴露组MDA含量的升高,差异有统计学意义(P0.05);而OTC单一暴露组玉米幼苗叶片中MDA含量无明显变化(P0.05);Cu~(2+)+OTC(20~40 mg/L)复合暴露组8~120 h MDA含量增加,差异有统计学意义(P0.05)。结论 Cu~(2+)单一暴露和Cu~(2+)+OTC复合暴露对玉米幼苗总根长有一定的抑制作用,且叶片组织发生氧化损伤。     

The Effects of pH and PEG 400–Water Cosolvents on Oxytetracycline–Magnesium Complex Formation and Stability

The effects of pH and PEG 400 on the stoichiometry, conformation, and stability of the magnesium–oxytetracycline (Mg⁺²–OTC) complex were evaluated. Circular dichroism (CD) and HPLC were used to investigate Mg⁺²–OTC complex formation and determine the stability of the complexes formed. The stoichiometry of the complex was determined to be a 1:1 molar ratio of Mg⁺² to OTC regardless of changes in pH, in the range 7–10, and regardless of the percentage of polyethylene glycol (PEG) 400 in solution. CD showed that the conformation assumed by Mg⁺²–OTC complex is sensitive to changes in pH, however, little to no effect was found when the PEG 400 concentration was varied. PEG 400 was found to effect the magnitude of complexation as evident by the dependence of CD peak intensity on the cosolvent concentration in solution. The Job's method confirmed that the formation of this complex increased with increasing PEG 400 concentration and was most favored at pH 8. HPLC analyses of OTC solutions at pH 9 revealed the formation of multiple degradation products after storage at 50°C. The incidence and magnitude of OTC degradation products were reduced in the presence of Mg⁺² and PEG 400. Despite the HPLC results of maintained OTC stability in magnesium-complexed solutions over time, visual inspection showed these solutions to have darkened, indicating that an oxidative process is responsible for initial degradation of OTC. Therefore, the need for additional measures (i.e., antioxidants) was established to ensure the long-term stability of OTC in solution.     

The Interaction Between Oxytetracycline and Divalent Metal Ions in Aqueous and Mixed Solvent Systems

The effects of pH, mixed solvent systems, and divalent metal ions on oxytetracycline (OTC) solubility and the interactions between OTC and metal ions in aqueous and mixed solvent systems were investigated. OTC solubility profiles were obtained for pH 4–9. The cosolvents studied were glycerin, propylene glycol, PEG 400, and 2-pyrrolidone with the following metal ions: magnesium, calcium, and zinc. OTC and its interactions with these metal ions were evaluated by solubility, NMR, circular dichroism (CD), and electron diffraction (ED) methods. At pH 5.6, no complexation occurred with these metal ions, but OTC zwitterion formed aggregates in aqueous solutions as shown by NMR spectra. The hydration of the metal ions was observed to affect OTC aggregation, with Mg⁺² causing the greatest OTC aggregation. At pH 7.5, OTC aggregation and metal–OTC complexation were observed in solutions with Ca⁺² and Mg⁺². Zinc ion was found to decrease OTC solubility because of zincate formation, which caused anionic OTC to precipitate. Electron diffraction revealed a relationship between OTC and metal–OTC complex crystallinity and solubility behavior. The zinc–OTC complex exhibited the highest crystallinity and lowest solubility at pH 8.0. Various cosolvents generally enhanced OTC solubility, with 2-pyrrolidone having the best solubility power. In OTC–metal-2-pyrrolidone and OTC–Zn⁺²-PEG 400 systems, circular dichroism provided evidence for the formation of soluble ternary complexes.