四环素调控系统修饰永生化大鼠星形胶质细胞株的构建及鉴定

目的构建四环素及其衍生物强力霉素诱导表达目的基因的永生化大鼠星形胶质细胞株。方法用脂质体法将逆转录病毒载体四环素调控系统中的质粒pRevTet-On转染病毒包装细胞 PT67,经筛选培养后获得病毒载体RevTet-On,采用RT-PCR进行鉴定,并应用NIH313细胞测定病毒滴度。将RevTet-On感染永生化大鼠星形胶质细胞,用有限稀释法挑选阳性细胞单克隆后扩大培养,每个克隆瞬时转染含萤光素酶报告基因的质粒pRevTRE-Lue,加入强力霉素48h后分别检测其萤光素酶活性值,挑选出强力霉素诱导表达高、背景表达低的细胞株并检测其诱导表达的时效、量效关系。结果 RT-PCR结果显示逆转录病毒包装成功,病毒最高滴度为7．4×105CFU／ml。RevTet-On转染永生化大鼠星形胶质细胞后挑选出48个单克隆,瞬时转染pRevTER-Luc后筛选出1株高表达低背景细胞株, 其诱导表达值为876．1 RLU,背景表达值为42．5 RLU,诱导倍数为20．6。该细胞株在加入诱导因子强力霉素1 h后目的基因即开始表达,在24 h时达到高峰,在强力霉素浓度100-2 000 ng/ml的范围内, 其诱导表达活性与药物浓度呈剂量依赖性。结论含四环素调控系统的永生化大鼠星形胶质细胞株诱导活性可靠,可用于调控表达外源基因的研究。     

管状骨增宽牵引成骨组织形态学变化的实验研究

目的 探讨管状骨增宽牵引后新骨形成的变化。方法 在成年山羊的后肢放置2只增宽牵引器。实验组9只术后第8天牵引，对照组3只不牵引。牵引完毕后不同时期，各宰杀3只，评价管状骨增宽牵引后新骨形成的质和量。结果 实验组胫骨平均增宽7．83mm，X射线见牵引间隙逐渐变模糊，暴露侧有骨不连，非暴露侧成骨良好，牵引完毕3个月，未暴露侧新形成板层骨与原来胫骨融为一体，而暴露侧骨不连区为致密纤维组织。结论 管状骨增宽牵引成骨后，两侧牵引间隙成骨不一致，良好的血供，对新骨形成至关重要。     

过氧化脲治疗四环素牙的远期疗效

目的评价10％过氧化睬凝胶漂白剂家庭漂白（In-home bleaching）治疗四环素牙的远期临床效果。方法用含10％过氧化脲的凝胶漂白剂。通过可由患者自行取戴的漂白托盘治疗四环素牙，观察其脱色效果及牙色复原等变化情况。结果306例四环素牙患者漂白总满意率为86．6％；随访6个月的201例中，有14．9％于6个月后出现不同程度的颜色复原。1～2年后，仍有较高的满意率。其中30例。每隔2年做1次巩固治疗。随访11年临床效果良好。结论10％过氧化脲凝胶漂白剂治疗四环素牙是有效的方法，着色度越轻治疗效果越好，着色度越重治疗效果越差。同时，漂白治疗具有一定的复原性，坚持巩固治疗。远期效果令人满意。     

The tetracycline analogs minocycline and doxycycline inhibit angiogenesis in vitro by a non-metalloproteinase-dependent mechanism

The tetracycline analogs minocycline and doxycycline are inhibitors of metalloproteinases (MMPs) and have been shown to inhibit angiogenesis in vivo. To further study the mechanism of action of these compounds we tested them in an in vitro model of angiogenesis: aortic sprouting in fibrin gels. Angiogenesis was quantitated in this system by a unique application of planar morphometry. Both compounds were found to potently inhibit angiogenesis in this model. To further characterize the activity of these compounds against MMPs, we determined the IC₅₀s of both compounds against representatives of three classes of metalloproteinases: fibroblast collagenase, stromelysin, and gelatinase A. Doxycycline was found to inhibit collagenase, gelatinase A and stromelysin with IC₅₀s of 452 M, 56 M and 32 M, respectively. Minocycline was found to inhibit only stromelysin in the micromolar range with an IC₅₀ of 290 M. Since these results suggest that these compounds may not have been inhibiting in vitro angiogenesis by an MMP-dependent mechanism, we decided to test the effects of the potent MMP inhibitor BB-94. This compound failed to inhibit aortic sprouting in fibrin gels, thus strongly suggesting that both doxycycline and minocycline act by an MMP-independent mechanism. These results have implications for the mechanism of action of tetracycline analogs, particularly where they are being considered for the treatment of disorders of extracellular matrix degradation including periodontal disease, arthritis, and tumor angiogenesis.     

Escherichia coli tetracycline efflux determinants in relation to tetracycline residues in chicken

ObjectiveTo screen for Escherichia coli (E. coli) resistant to tetracycline, followed by identification of tet efflux genes by polymerase chain reaction (PCR). In addition, detection of tetracycline residues in chicken livers and kidneys were conducted using high performance liquid chromatography-tandem quadrupole mass spectrometry (HPLC-MS-MS).MethodsStrains of E. coli were isolated from samples of chicken colon and screened for tetracycline resistance. Tetracycline genes conferring resistance (Tc^r) were detected by polymerase chain reaction (PCR). Most of the isolates were resistant to tetracycline (97.9%).ResultsPCR analysis indicated that Tc^r E. coli R-plasmids contained tet(A), tet(B) and a combination of both efflux genes. None of the isolates contained other efflux tet genes tet (C, D, E and Y). High performance liquid chromatography-tandem quadrupole mass spectrometry (HPLC-MS-MS), a sensitive technique, was used to detect residues of chlortetracycline (CTC), oxytetracycline (OTC), doxycycline (DC) in chicken livers and kidneys. The samples containing tetracycline residues were at 0.13-0.65 pg/μL levels.ConclusionsTetracycline and other antibiotics are commonly used in the poultry and meat production industry for prevention of microbial infections. Multiple antibiotic resistant bacteria in Oman have increased to alarming levels, threatening public health, domestic and may have adverse effect on environment.     

色谱柱参数对盐酸四环素有关物质HPLC分析的影响研究

摘要：目的 分析色谱柱参数对盐酸四环素有关物质HPLC分析的影响，筛选影响关键杂质分离度以及理论塔板数的主要 柱参数。方法 针对《中国药典》2020版中盐酸四环素有关物质检查的色谱条件，使用多个品牌不同型号的色谱柱进行色谱分 析，使用SPSS软件进行模型回归，得到柱参数与目标因子分离度及理论塔板数的回归方程，并用实测值进行验证。结果 色谱 柱参数C是影响杂质4-差向四环素和土霉素分离度(R12)的重要参数，利用柱参数C可快速预测不同色谱柱的相似度，进而筛选 适宜四环素分析的色谱柱；探讨了金霉素理论塔板数(R5N)与柱参数之间的关系，其中参数B2对R5N影响较大。结论 建立柱参 数与色谱分析目标因子之间的联系，为盐酸四环素有关物质测定选择合适的色谱柱提供便利与指导。     

In-vitro activity of the novel fluorocycline eravacycline against carbapenem non-susceptible Acinetobacter baumannii

The activity of eravacycline was compared with that of anti-Acinetobacter reference antimicrobials against carbapenem non-susceptible Acinetobacter baumannii isolates associated with an acquired OXA or up-regulation of the intrinsic OXA-51-like enzyme. Antimicrobial susceptibility testing was performed by broth microdilution of 286 non–duplicate, carbapenem non-susceptible A. baumannii isolates to eravacycline, amikacin colistin, doxycycline, imipenem, levofloxacin, meropenem, minocycline, sulbactam, tigecycline and tobramycin.Eravacycline showed greater activity than the comparators of the tetracycline class, levofloxacin, amikacin, tobramycin and colistin. The eravacycline MIC_50/90 values were 0.5/1?mg/L and those for tigecycline, minocycline and doxycycline were 1/2, 4/8 and 32/?≥?64?mg/L, respectively. In conclusion, eravacycline was the most potent antibiotic of those tested against A. baumannii, including isolates that were resistant to sulbactam, imipenem/meropenem, levofloxacin and amikacin/tobramycin. Eravacycline has the potential to become a useful addition to the limited armamentarium of drugs that can be used to treat this problem pathogen.     

盐酸美他环素致色素沉着3例分析

美他环素属四环素类抗生素,用于衣原体感染、立克次体病、支原体肺炎、回归热等非细菌性感染及敏感细菌所致胃肠道、泌尿系统、呼吸系统、皮肤软组织感染等有较好的疗效.近几年使用过程中发现个别患者有轻微的光敏反应,虽然反应发生率小,反应程度较低,但也应引起足够的重视,以免给患者带来身体及精神上的痛苦.     

UPLC-ESI-MS/MS检测畜、禽肉中土霉素、四环素、金霉素残留量

目的：建立超高效液相色谱-电喷雾串联四极杆质谱快速测定畜、禽肉中土霉素、四环素、金霉素的方法。方法：采用超高效液相色谱-电喷雾串联四极杆质谱仪,多离子反应监测（MRM）定量法,通过对试样净化预处理、色谱条件、质谱参数等的优化选择和方法回收率、精密度等的验证,建立了同步准确定量测定肉类食品中土霉素、四环素、金霉素的理想方法。结果：土霉素、四环素、金霉素的最低检出限（LOD）分别为0.1、0.1、0.5μg/kg,在5.0-80.0 ng/ml的线性范围内,相关系数r均大于0.99,回收率在82.6%-111%。结论：采用液相色谱-电喷雾串联四极杆质谱仪,可快速测定畜、禽肉样品中土霉素、四环素、金霉素含量,结果准确可靠,重复性好,灵敏度高。     

联合用药治疗非淋球菌性尿道炎疗效观察

目的:寻求一种快速治疗非淋球菌性生殖道炎症(粘液脓性宫颈炎)和减少交叉感染的治疗方法.方法:共280例患者,第一组用阿奇霉素口服,第二组用阿齐霉素口服 四环素外用,第三组阿奇霉素、加替沙星口服 四环素外用治疗.结果:第一组、第二组及第三组的有效率分别为71%、82%及94%.结论:阿奇霉素、加替沙星口服 四环素外用治疗非淋菌性生殖道炎症,疗效好,疗程短,可获满意疗效.