不同规格怀牛膝不同极性部位HPLC指纹图谱

目的研究并比较不同规格怀牛膝不同极性部位的HPLC指纹图谱,探索其内部质量差异,为该药材的规格标准完善及临床用药提供参考。方法将怀牛膝用体积分数75%乙醇水浴回流提取,得体积分数75%乙醇回流提取物,用40 mL水溶解后,依次用石油醚、三氯甲烷、乙酸乙酯、正丁醇进行萃取,得到各萃取相及萃取后的水相,浓缩至浸膏,采集各部位HPLC指纹图谱;运用相似度、综合聚类法进行数据分析,同时对其不同部位的指纹图谱进行比对分析。结果石油醚、氯仿部位均标定了11个共有峰,乙酸乙酯部位标定了10个共有峰,正丁醇部位标定了19个共有峰,水部位标定8个共有峰;氯仿部位指纹图谱相似度差异较大,其他部位指纹图谱相似度差异较小,均在0.9以上;石油醚部位指纹图谱差异主要体现在峰高,乙酸乙酯部位、氯仿部位、水部位的化学成分种类及峰高均存在差异;综合聚类分析能将不同规格怀牛膝区分开。结论不同规格怀牛膝内部质量存在差异;实验中所建立的HPLC指纹图谱可以全面反映不同规格怀牛膝的化学成分分布,为不同规格怀牛膝的整体质量评价提供参考。     

The effect of three rotational speed settings on torque and apical force with vortex rotary instruments in vitro

Introduction

Both the number of rotations in curved canals and torque are related to fracture resistance of nickel-titanium rotaries via the respective mechanisms of brittle and flexural failure. Increased rotational speed (rotations per minute [RPM]) may lead to higher cutting ability and could overcompensate for increased fatigue. The impact of three RPM settings on peak torque (Nmm) and apically directed force (N) during root canal preparation were investigated in vitro.

Methods

S-shaped canals in plastic blocks (n = 12/group) were instrumented with Vortex rotaries (Dentsply Tulsa Dental, Tulsa, OK) sizes #15 to 30 with a .04 taper. Rotaries were used in a manufacturer-recommended sequence: #30, 25, and 20 in a crown-down approach progressively deeper into the canal, #15 to the working length, and apical enlargement with sizes 20 and 25 to WL. A total of 216 preparation procedures were performed using a custom testing platform. RPM was set at 200, 400, or 600; automated axial feed mirrored clinical handling, resulting in two in-and-out movements, each to preset insertion depths. Torque and apical force were continuously recorded and peak values statistically contrasted using analysis of variances.

Results

No file fractures were observed in any of the three experimental groups. Peak torques and forces varied by instrument size and were highest at 200 RPM for all sizes; torque and force were reduced by 32% and 48%, respectively, at 400 RPM (P < .001). Increasing RPM to 600 did not result in further reductions. The number of discernible peaks for torque (threshold: 0.3 Nmm) and force (threshold: 0.2 N) significantly decreased from 200 RPM to 400 RPM and did not decrease further with 600 RPM.

Conclusions

Under the present experimental conditions, rotational speed had a significant impact on preparation with Vortex rotaries, with instruments at 400 RPM generating less torque and force compared with 200 RPM.     

INAUGURAL ARTICLE by a Recently Elected Academy Member:Helicity and singular structures in fluid dynamics

Helicity is, like energy, a quadratic invariant of the Euler equations of ideal fluid flow, although, unlike energy, it is not sign definite. In physical terms, it represents the degree of linkage of the vortex lines of a flow, conserved when conditions are such that these vortex lines are frozen in the fluid. Some basic properties of helicity are reviewed, with particular reference to (i) its crucial role in the dynamo excitation of magnetic fields in cosmic systems; (ii) its bearing on the existence of Euler flows of arbitrarily complex streamline topology; (iii) the constraining role of the analogous magnetic helicity in the determination of stable knotted minimum-energy magnetostatic structures; and (iv) its role in depleting nonlinearity in the Navier-Stokes equations, with implications for the coherent structures and energy cascade of turbulence. In a final section, some singular phenomena in low Reynolds number flows are briefly described.This inaugural article, although long delayed, is now fortuitously quite timely for various reasons. First, helicity in fluid dynamics is a measure of the knottedness and/or linkage of the vortex lines of a flow (1), invariant under ideal-fluid Euler evolution. Knotted vortices were first conceived by Lord Kelvin (then Sir William Thomson) in 1868 (2), but have only recently been unambiguously observed: a vortex in the form of a trefoil knot has been generated in a remarkable experiment by Kleckner and Irvine (3) by means of an ingenious technique that can in principle be adapted to generate vortices of arbitrarily linked or knotted form. The possible existence of knotted vortices is therefore no longer a matter of mere speculation!Second, helicity has long been known to be of crucial importance in turbulent dynamo theory—the theory of the spontaneous growth of a magnetic field in a conducting fluid in turbulent motion. The associated chirality of the flow is responsible for the α-effect (4), which is a crucial ingredient of the dynamo process in stars and planets. The von Karman sodium (VKS) experiment (5) developed in France over the last decade has at last provided convincing evidence for a turbulent dynamo mechanism that undoubtedly involves this α-effect in conjunction with differential rotation and strong diffusive processes.Third, the process of magnetic relaxation of a knotted magnetic flux tube in a perfectly conducting fluid under the topological constraint of invariant helicity leads in a natural physical way to the concept of the energy spectrum of knots and links (6). The minimum energy configurations obtained by this procedure are, with certain qualifications, essentially the same as the ideal or tight knot configurations introduced by Katritch et al. (7) which minimize the length-to-diameter ratio of knotted tubes. Tight knots have found wide application in polymer physics and molecular biology, as discussed in recent workshops of the Isaac Newton Institute for Mathematical Sciences (8, 9), and huge progress has been made in determining all tight configurations for links and knots up to 9 and 10 crossings, respectively (10). In particle physics, a striking correlation has been noted between the knot/link energies and the mass/energies of glueballs in the quark–gluon plasma (11); the subject has perhaps come full circle since the time of Kelvin!The time is therefore ripe to review some of the salient features of these and related phenomena in which helicity plays a central role, and I take this welcome opportunity to do so. I include also, at the suggestion of a referee of this article, a section on certain structures that can arise in flows that are dominated by viscosity, and that nevertheless exhibit structures of nontrivial topology.     

Left ventricular blood flow patterns at rest and under dobutamine stress in healthy pigs

Intracardiac blood flow patterns are affected by the morphology of cardiac structures and are set up to support the heart's pump function. Exercise affects contractility and chamber size as well as pre‐ and afterload. The aim of this study was to test the feasibility of four‐dimensional phase contrast cardiovascular MRI under pharmacological stress and to study left ventricular blood flow under stress. 4D flow data were successfully acquired and analysed in 12 animals. During dobutamine infusion, heart rate and ejection fraction increased (82 ± 5 bpm versus 124 ± 3 bpm/46 ± 9% versus 65 ± 7%; both p < 0.05). A decrease in left ventricular end‐diastolic volume (72 ± 14 mL versus 55 ± 8 mL; p < 0.05) and end‐systolic volume (40 ± 15 mL versus 19 ± 6 mL; p < 0.05) but no change in stroke volume were observed. Trans‐mitral diastolic inflow velocity increased under dobutamine and the trajectory of inflowing blood was directed towards the anterior septum with increased inflow angle (26 ± 5°) when compared with controls (15 ± 2°). In 5/6 animals undergoing stress diastolic vortices developed later, and in 3/6 animals vortices collapsed earlier with significantly smaller cross‐sectional area during diastole. The vorticity index was not affected. Under the stress condition direct flow (% ejection within the next heart beat) increased from 43 ± 6% to 53 ± 8%. 4D MRI blood flow acquisition and analysis are feasible in pig hearts under dobutamine‐induced stress. Flow patterns characterized by high blood velocity and antero‐septally oriented diastolic inflow as well as decreased ventricular volumes are unfavourable conditions for diastolic vortex development under pharmacological stress, and cardiac output is increased by a rise in heart rate and directly ejected left ventricular blood volume.     

Adenocarcinoma of the oesophagogastric junction Siewert II: An oesophageal cancer better cured with total gastrectomy

IntroductionType II AEG is now considered as oesophageal cancer in the seventh and eighth edition of TNM classification but optimal surgical approach for these tumors remains debated. The objective of the study is to assess and compare surgical and oncological outcomes of two surgical approaches: superior polar oesogastrectomy (SPO) or total gastrectomy (TG) in patients with type II adenocarcinoma of the oesophagogastric junction (AEG).Material and methods183 patients with type II AEG treated from 1997 to 2010 in 21 French centers by SPO or TG were included in a multicenter retrospective study. The surgical and oncological outcomes were compared between these two surgical approaches.ResultsA TG was performed in 64 (35%) patients whereas 119 (65%) patients were treated by SPO with transthoracic approach in 100 of them (83.2%) and transhiatal approach with cervicotomy in 19 (16.8%). Surgical outcomes were comparable between the two approaches with a postoperative mortality rate of 4.9% and a severe operative morbidity rate within 30 days of 15.3%. Median survival in patients operated on by TG was of 46 months compared to 27 months in patients treated by SPO (p = 0.118). At multivariate analysis, TG appears to be an independent good prognostic factor compared to SPO (HR = 1.847; p = 0.008). However, TG was also associated with a higher rate of incomplete resection, (12.5% vs 5.9%; p = 0.120).ConclusionWhen TG allows obtaining tumor-free resection margins, this approach should be preferred to SPO.     

Blood-Brain Barrier Permeability of Asiaticoside,Madecassoside and Asiatic Acid in Porcine Brain Endothelial Cell Model

Neurotherapeutic potentials of Centella asiatica and its reputation to boost memory, prevent cognitive deficits and improve brain functions are widely acknowledged. The plant's bioactive compounds, i.e. asiaticoside, madecassoside and asiatic acid were reported to have central nervous system (CNS) actions, particularly in protecting the brain against neurodegenerative disorders. Hence, it is important for these compounds to cross the blood-brain barrier (BBB) to be clinically effective therapeutics. This study aimed to explore the capability of asiaticoside, madecassoside and asiatic acid to cross the BBB using in vitro BBB model from primary porcine brain endothelial cells (PBECs). Our findings showed that asiaticoside, madecassoside and asiatic acid are highly BBB permeable with apparent permeability (P_app) of 70.61 ± 6.60, 53.31 ± 12.55 and 50.94 ± 10.91 × 10^?6 cm/s respectively. No evidence of cytotoxicity and tight junction disruption of the PBECs were observed in the presence of these compounds. Asiatic acid showed cytoprotective effect towards the PBECs against oxidative stress. This study reported for the first time that Centella asiatica compounds demonstrated high capability to cross the BBB, comparable to central nervous system drugs, and therefore warrant further development as therapeutics for the treatment of neurodegenerative diseases.     

Posterior polar cataract: A review

Posterior polar cataract is a rare form of congenital cataract. It is usually inherited as an autosomal dominant disease, yet it can be sporadic. Five genes have been attributed to the formation of this disease. It is highly associated with complications during surgery, such as posterior capsule rupture and nucleus drop. The reason for this high complication rate is the strong adherence of the opacity to the weak posterior capsule. Different surgical strategies were described for the handling of this challenging entity, most of which emphasized the need for gentle maneuvering in dealing with these cases. It has a unique clinical appearance that should not be missed in order to anticipate, avoid, and minimize the impact of the complications associated with it.