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.     

红蓝光联合多西环素治疗面部中重度痤疮的效果

目的 探究红蓝光联合多西环素治疗面部中重度痤疮的临床效果。方法 选取2021年3月-2022年12月清镇市第一人民医院收治的60例面部中、重度痤疮患者,经随机数字表法分对照组和治疗组,每组30例。对照组采用多西环素治疗,治疗组联合红蓝光治疗,比较两组临床效果、皮损情况及皮肤病生活质量评分。结果 治疗组治疗总有效率为93.33%,高于对照组的73.33%（P＜0.05）;治疗组治疗后皮损数目、面积均小于对照组（P＜0.05）;治疗组治疗后皮肤病生活质量评分为（3.07±0.87）分,低于对照组的（6.28±1.24）分（P＜0.05）。结论 红蓝光联合多西环素治疗面部中重度痤疮疗效较为理想,可减轻患者皮损程度,有助于提升患者生活质量,尽早恢复正常生活。     

pTet-on骨骺干细胞株的建立和pTRE-甲状旁腺相关蛋白(1-36)反应质粒的构建

目的 建立pTet-on骨骺干细胞株,克隆甲状旁腺相关蛋白[PTHrP(1-36)]基因并构建反应质粒pTRE-PTHHrP(1-36).方法 用脂质体介导的基因转染技术将pTet-on质粒转染于永生化骨骺干细胞,G418筛选得到稳定克隆,再瞬时转染pTRE-2Hyg-Luc质粒并筛选出高水平诱导、低背景表达的永生化骨骺干细胞系.以RT-PCR方法获得带有酶切位点PTHrP(1-36)基因片段,与载体pTRE-2Hyg均双酶切后连接,转化扩增后对重组质粒进行提取和酶切、测序鉴定.结果 筛选到1株诱导后荧光素酶的表达活性增加50倍的骨骺干细胞系;经酶切图谱分析和DNA序列测定证实目的基因已经插入重组质粒.结论 筛选得到的永生化骨骺干细胞株受强力霉素诱导后能够低背景、高水平表达;成功克隆PTHrP(1-36)基因并构建了反应质粒pTRE-PTHrP(1-36),为进一步精确调控PTHrP(1-36)基因的表达奠定了基础.     

盐酸多西环素胶囊治疗寻常痤疮的临床观察

目的：为评价盐酸多西环素胶囊治疗寻常痤疮的疗效及不良反应。方法：对60例寻常痤疮随机分为二组治疗,A组（30例）用盐酸多西环素胶囊治疗,B组（30例）用二甲胺四环素胶囊治疗, 治疗时间为21天,结果：治疗前后,A组和B组的炎性皮损数减少明显（P＜0．05）,盐酸多西环素胶囊组无明显不良反应,结论：盐酸多西环素胶囊治疗寻常痤疮有效,副作用少。     

Pin1在皮肤组织中的表达以及可诱导转基因小鼠模型的建立

目的 观察Pin1在皮肤中的表达情况,构建Pin1在皮肤中可诱导表达的转基因小鼠模型。方法 将小鼠Pin1基因克隆到改造过的可与Myc标签蛋白融合的pTRE2载体中,并将线性化的DNA通过显微注射的方式构建TRE-Pin1小鼠。结果 我们成功获得TRE-Pin1转基因首建鼠,该小鼠与上皮特异的K14-rtTA转基因小鼠配繁,获得Pin1在皮肤上皮特异性的可诱导表达的双转基因小鼠;我们通过将多西霉素（又名强力霉素, Doxycycline）加入饮水的方式诱导Pin1基因的表达,并通过Western blot,免疫组织化学等方式证明了Pin1蛋白在皮肤上皮中能特异性地过表达。我们还发现内源的Pin1在皮肤中主要表达于上皮细胞。结论 我们成功地构建Pin1在皮肤中可诱导表达的转基因小鼠模型,为后续研究Pin1在皮肤中的功能奠定基础。     

Do antibacterial and antifungal combinations have better activity against clinically relevant fusarium species? in vitro synergism

The aim of this study was to evaluate the susceptibility of 20 clinical isolates of Fusarium spp. to classic antifungals [amphotericin B (AmB), itraconazole (ITR), voriconazole (VRC) and caspofungin (CAS)] and to non-antifungal agents [amiodarone (AMD), doxycycline (DOX) and moxifloxacin (MFX)] by the broth microdilution method. Combinations between these antifungal and non-antifungal agents were also evaluated to determine the fractional inhibitory concentration indices using the chequerboard technique. Synergistic interactions were observed for the following combinations (% synergism): AMD?+?VRC, 80%; MFX?+?AmB, 75%; AMD?+?AmB, 65%; DOX?+?VRC, 60%; MFX?+?VRC, 55%; DOX?+?AmB, 50%; and AMD?+?CAS, 30%. Synergism was not observed for associations with ITR. Antagonism was not seen in any combination. These findings suggest that the combinations of AMD, DOX or MFX with AmB or VRC to have potential for future in vivo investigations.     

Effect of residual doxycycline concentrations on resistance selection and transfer in porcine commensal Escherichia coli

Pig feed may contain various levels of antimicrobial residues due to cross-contamination. A previous study showed that a 3% carry-over level of doxycycline (DOX) in the feed results in porcine faecal concentrations of approximately 4?mg/L.The aim of this study was to determine the effect of residual DOX concentrations (1 and 4?mg/L) in vitro on selection of DOX–resistant porcine commensal Escherichia coli and transfer of their resistance plasmids.Three different DOX–resistant porcine commensal E. coli strains and their plasmids were characterised. These strains were each brought in competition with a susceptible strain in a medium containing 0, 1 and 4?mg/L DOX. Resistant bacteria, susceptible bacteria and transconjugants were enumerated after 24?h and 48?h.The tet(A)–carrying plasmids showed genetic backbones that are also present among human E. coli isolates. Ratios of resistant to susceptible bacteria were significantly higher at 1 and 4?mg/L DOX compared with the blank control, but there was no significant difference between 1 and 4?mg/L. Plasmid transfer frequencies were affected by 1 or 4?mg/L DOX in the medium for only one of the resistance plasmids.In conclusion, DOX concentrations of 1 and 4?mg/L can select for resistant E. coli in vitro. Further research is needed to determine the effect of these concentrations in the complex environment of the porcine intestinal microbiota.     

The effect of doxycycline treatment on the postvaccinal immune response in pigs

The effect of a seven-day antibiotic therapy with doxycycline was investigated on the postvaccinal humoral and cellular immune response in pigs. The selected parameters of non-specific immunity were also studied. Fifty pigs were used (control not vaccinated (C, n = 10), control vaccinated (CV, n = 20), and experimental — received doxycycline (DOXY, n = 20)). For vaccination live-attenuated vaccine against pseudorabies (PR) was used. From day − 1 to day 5 pigs from DOXY group received doxycycline orally with drinking water, at the recommended dose. Pigs from DOXY and CV groups were vaccinated at 8 and 10 weeks of age. The results of the present study showed that cell-mediated postvaccinal immune response can be modulated by oral treatment with doxycycline. Significantly lower values of stimulation index were observed after PRV restimulation in doxycycline-treated pigs. Moreover, in the DOXY group a significant decrease in IFN-γ production after PRV restimulation was noted. The significantly lower number of CD4+CD8 + cells was also observed in doxy-treated, vaccinated pigs, 2 weeks after final vaccination. Simultaneously, specific humoral response was not disturbed. This study demonstrated the importance of defining the immune modulatory activity of doxycycline because it may alter the immune responses to vaccines. The exact mechanism of T-cell response suppression by doxycycline remains to be elucidated, however the influence of doxycycline on the secretion of various cytokines, including IFN-γ, may be considered as a possible cause. The present observations should prompt further studies on the practical significance of such phenomena in terms of clinical implications.     

壳聚糖宫颈抗菌膜联合多西环素治疗非淋菌性宫颈炎疗效观察

目的 观察壳聚糖宫颈抗菌膜联合多西环素治疗非淋菌性宫颈炎的疗效及安全性.方法 选取非淋菌性宫颈炎患者135例,根据治疗方案的不同分为研究组（90例）与对照组（45例）.研究组给予壳聚糖宫颈抗菌膜联合多西环素进行治疗,对照组仅给予多西环素治疗.观察两组患者的治疗有效率、病原体转阴率及不良反应发生率等.结果 研究组总治疗有效率为88.89％,显著高于对照组的53.33％ （P ＜0.05）;研究组病原体转阴率为77.78％,显著高于对照组额的44.44％ （P ＜0.05）.治疗期间,研究组患者头晕、恶心、食欲不振、上腹部不适等不良反应与对照组相比无显著差异（P＞0.05）.结论 壳聚糖宫颈抗菌膜联合多西环素治疗非淋菌性宫颈炎的临床疗效确切,能够有效提高治疗有效率,提高病原体的转阴率,且不良反应低,值得推广.     

Doxycycline attenuates acute lung injury following cardiopulmonary bypass: involvement of matrix metalloproteinases

Acute lung injury (ALI) was one of the major complications after cardiopulmonary bypass (CPB). Matrix metalloproteinases (MMPs) play an important role in ALI following CPB. In this study, we investigated the effects of doxycycline (DOX), a potent MMP inhibitor, on MMP-9 and ALI in the rat model of CPB. 48 adult male Sprague-Dawley rats were randomized into four groups: group I (Control group, underwent cannulation + heparinization only); group II (CPB group, underwent 60-minutes of normothermic CPB); group III (Low-dose treatment group, underwent 60-minutes of normothermic CPB with DOX gavage 30 mg/kg ×1 week ahead of CPB); and group IV (High-dose treatment group, underwent 60-minutes of normothermic CPB with DOX gavage 60 mg/kg ×1 week ahead of CPB). The effects of doxycycline on ALI were determined by measuring the lung Wet/Dry ratio, the inflammation of bronchoalveolar lavage fluid (BALF) and the ultrastructural changes of the lungs. The role of doxycycline on MMP-9 was assessed by the plasma concentration, the activity and the expression in lung tissue. Our results demonstrated that the lung Wet/Dry weight ratio and the inflammatory mediators (TNF-α, IL-1β) in BALF were decreased significantly with doxycycline treatment. The lung damages were attenuated by doxycycline. The levels of plasma concentration, the activity and the expression of MMP-9 in lung tissue were suppressed with doxycycline and the effects were dose dependent. Doxycycline could suppress the expression of MMP-9 and cytokines, and improve the ALI following CPB.