Crystal structure and functional analysis of tetracenomycin ARO/CYC: implications for cyclization specificity of aromatic polyketides

Polyketides are a class of natural products with highly diverse chemical structures and pharmaceutical activities. Polyketide cyclization, promoted by the aromatase/cyclase (ARO/CYC), helps diversify aromatic polyketides. How the ARO/CYC promotes highly specific cyclization is not well understood because of the lack of a first-ring ARO/CYC structure. The 1.9 A crystal structure of Tcm ARO/CYC reveals that the enzyme belongs to the Bet v1-like superfamily (or STAR domain family) with a helix-grip fold, and contains a highly conserved interior pocket. Docking, mutagenesis, and an in vivo assay show that the size, shape, and composition of the pocket are important to orient and specifically fold the polyketide chain for C9-C14 first-ring and C7-C16 second-ring cyclizations. Two pocket residues, R69 and Y35, were found to be essential for promoting first- and second-ring cyclization specificity. Different pocket residue mutations affected the polyketide product distribution. A mechanism is proposed based on the structure-mutation-docking results. These results strongly suggest that the regiospecific cyclizations of the first two rings and subsequent aromatizations take place in the interior pocket. The chemical insights gleaned from this work pave the foundation toward defining the molecular rules for the ARO/CYC cyclization specificity, whose rational control will be important for future endeavors in the engineered biosynthesis of novel anticancer and antibiotic aromatic polyketides.     

Auto-inflammatory challenge of the endolymphatic sac – Cochlear damage measured by distortion product oto-acoustic emissions

Conclusion: Twenty-five rats were challenged by an immunologic attack of the endolymphatic sac. After 6 months, distortion product oto-acoustic emissions (DPOAE) revealed a dysfunction of the outer hair cells and immunological active cells were observed in the endolymphatic sac. This information could contribute to the understanding of Ménière’s disease. Objectives: This study investigated if an autoimmune challenge of the endolymphatic sac could affect DPOAE output measurements in rats. Also, a potential autoimmune cell infiltration of the endolymphatic sac was investigated. Methods: Eighteen Lewis rats were immunized with a crude endolymphatic sac extract in complete Freund’s adjuvant. Seven control animals were injected with Freund’s adjuvant in saline. Cochlear damage was estimated by DPOAE dynamics 3 weeks and 6 months after the immunization. Infiltrative cells in the endolymphatic sac were investigated with transmission electron microscopy. Results: The hearing assessment 6 months after immunization revealed a reduction of the DPOAE, on the full range of frequencies (2–63 kHz) in an average of the mean, of 2 dB ± 1.1 in the immunized group compared to the controls (p < 0.05). The same test showed a 2.5 dB decrease from 2 to 5 kHz (p < 0.01). Immunological active cells were observed in the endolymphatic sac in most of the immunized rats.     

四川医疗器械产品质量监督抽验现状及对策探讨

目的：探索四川医疗器械产品质量监督抽验优势与不足,促进产品质量监管的规范化、制度化。方法：通过文献查阅,到质量监管部门调研与访谈,分析影响因素,提出思考与对策。结果：四川产品质量监督取得显著成绩的同时,在抽验品种数、范围和抽样任务等方面不适应产品发展需要。结论：要保证产品质量,必须扩大抽验范围、增加样品来源、提高抽验人员素质、强化政府监管职能,才能促进四川医疗器械健康发展。     

Intraoperative 3D imaging control during subthalamic Deep Brain Stimulation procedures using O-arm® technology: Experience in 15 patients

ObjectiveO-arm^® now gives us the opportunity not only to perform 2D but also 3D scans during deep brain stimulation (DBS) procedures. We present our experience with the intraoperative use of this device. Our objective was to measure the geometrical accuracy of electrode placement during surgical procedures driven under O-arm^® control.MethodsFifteen patients underwent STN-DBS. For the first 4 patients, 3D scans were performed at the end of the procedure. We calculated the accuracy of electrode positioning, i.e. the distance between final electrode positioning and the planned trajectory. For the next 11 patients, who underwent both intraoperative and final 3D scan, we also calculated the accuracy of the microelectrode positioning.ResultsAverage stimulation-induced improvement of UPDRS-III score was 52.5 ± 15%. For the first 4 patients, the mean electrode positioning accuracy was 1.46 ± 0.56 mm. For the 11 patients who underwent intraoperative 3D scan, the mean microelectrodes positioning accuracy was 1.59 ± 1.1 mm. Aberrant positioning was detected in two cases, and was analyzed by fusing 3D scan with preoperative MR images. The definite electrodes positioning accuracy was 1.05 ± 0.54 mm.ConclusionIntraoperative 3D scan is feasible, and can help us detect and correct early aberrant trajectories.     

Editorial comment: variables affecting the presence of mesenchymal stromal cells in the peripheral blood and their relationship with apheresis product

Paediatric haematology began to establish itself as a speciality in the UK just over 60 years ago. In that time, clinical trials involving all the specialist centres in the country, and based on scientific advances, have dramatically improved the outlook for children with a range of malignant and non-malignant disorders, but particularly acute leukaemia. As in many specialties, multidisciplinary teams have played a major role in delivering these advances. With these structures in place at a national level, perhaps, of all specialities, paediatric haematology is poised to benefit from the new developments in precision medicine, gene editing and immunotherapy.     

Lyophilization Process Design and Development: A Single-Step Drying Approach

High-throughput lyophilization process was designed and developed for protein formulations using a single-step drying approach at a shelf temperature (T_s) of ≥40°C. Model proteins were evaluated at different protein concentrations in amorphous-only and amorphous-crystalline formulations. Single-step drying resulted in product temperature (T_p) above the collapse temperature (T_c) and a significant reduction (of at least 40%) in process time compared to the control cycle (wherein T_p < T_c). For the amorphous-only formulation at a protein concentration of ≤25 mg/mL, single-step drying resulted in product shrinkage and partial collapse, whereas a 50 mg/mL concentration showed minor product shrinkage. The presence of a crystallizing bulking agent improved product appearance at ≤25 mg/mL protein concentration for single-step drying. No impact to other product quality attributes was observed for single-step drying. Vial type, fill height, and scale-up considerations (i.e., choked flow, condenser capacity, lyophilizer design and geometry) were the important factors identified for successful implementation of single-step drying. Although single-step drying showed significant reduction in the edge vial effect, the scale-up considerations need to be addressed critically. Finally, the single-step drying approach can indeed make the lyophilization process high throughput compared to traditional freeze-drying process (i.e., 2-step drying).     

盐制对杜仲治疗去卵巢大鼠骨质疏松症影响的研究

目的：研究杜仲及其盐制品对去卵巢大鼠骨质疏松症的治疗作用,并探讨盐制对其治疗作用的影响。方法40只SD雌性大鼠分为伪手术组、模型对照组、杜仲生品治疗组和杜仲盐制品治疗组,除假手术组施行假手术外,其余均行手术彻底摘除卵巢,术后4周开始杜仲生品及盐制品水提液灌胃给药（4．0 g／kg?d）,实验过程称体质量,连续给药12周后,颈动脉取血,测定血钙（S－Ca）、血磷（S－P）含量,ELISA试剂盒双抗体夹心法测定血清碱性磷酸酶（ALP）、骨钙素（OCN）、雌二醇（E2）含量;动物处死后剥取完整子宫称重,采用HE染色法进行子宫病理学检查,剥离双侧股骨,双能X射线衍射法测定大鼠股骨骨密度。 HE染色法观察股骨骨小梁形态和成骨细胞数量,micro－CT扫描观察股骨骨小梁微体系结构。结果杜仲生品及盐制品能有效抑制去卵巢所致的大鼠体重增加,升高血清钙、雌二醇的含量,降低血磷、碱性磷酸酶和骨钙素的含量。增加大鼠股骨骨密度,改善股骨骨小梁微体系结构,增加股骨骨小梁成骨细胞数量,且长期用药对子宫无明显刺激作用。结论杜仲生品及盐制品对于大鼠去卵巢所引起的骨质疏松症有良好治疗作用,且盐制品效果优于生品。