A new oral erosion controlled drug delivery system with a late burst in the release profile

A new oral erosion controlled drug delivery system on the basis of polyvinyl alcohols with a late burst in the release profile is developed. This late burst occurs after addition of sparingly soluble substances, either excipients like carboxylic acids and neutral cellulose or drugs like theophylline and theobromine. The onset time between 4 and 12 h and the extent of the burst between 20 and 60% are well reproducible and depend on the type of the used additive and the particle size of the basic polymer. For dissociating additives like glutamic acid, the pH within the swelling and eroding hydrocolloid tablet is decisive, differing from the pH of the dissolution medium and controlling the release process. Only polyvinyl alcohols with a ratio of viscosity number to degree of hydrolysis in the range from 2.3 to 3 exhibit acceleration of release in the final phase. As mechanism of the burst, enforced erosion of the gel layer, surrounding the tablet core, could be identified.     

经伤椎椎弓根内固定联合椎间植骨融合术在下腰椎爆裂性骨折治疗中的应用

[目的]探讨经伤椎椎弓根内固定联合椎间植骨融合术在下腰椎爆裂性骨折治疗中的应用价值。[方法]采用经伤椎椎弓根内固定联合椎间植骨融合术治疗下腰椎爆裂性骨折,并比较手术前后X线检查和脊髓神经恢复情况。[结果]在随访期间复查128例患者的X射线片显示内固定位置良好,未出现螺钉松动、断钉、断棒等现象;未发生感染、排异等不良反应;椎体前缘高度、椎体后缘高度及Cobb角与术前比较有明显差异,且差异具有统计学意义(P﹤0.05)。这表明伤椎高度、生理曲度恢复良好;随访期间伤椎椎体高度、脊椎序列及椎管形态维持良好。CT平扫显示椎管内骨块复位良好,伤椎经撑开复位后的空隙被植骨充填;神经功能不全损伤患者均有不同程度功能恢复。[结论]经伤椎椎弓根内固定联合椎间植骨融合术不仅能复位骨折,重建脊柱高度,而且能提供晚期脊柱的稳定性,防止高度丢失,减少内固定并发症,是一种较为理想的治疗方法。     

A novel nested liposome drug delivery vehicle capable of ultrasound triggered release of its payload

The use of focused ultrasound can be an effective method to locally highlight tumor tissue and specifically trigger the activation of echogenic drug delivery vehicles in an effort to reduce systemic chemotherapy side effects. Here we demonstrate a unique ultrasound triggered vehicle design and fabrication method where the payload and a perfluorocarbon gas microbubble are both encapsulated within the internal aqueous space of a liposome. This nested lipid shell geometry both stabilized the microbubble and ensured it was spatially close enough to interact with the liposome membrane at all times. The internal microbubble was shown to fragment the outer liposome membrane upon exposure to ultrasound at intensities of 1-1.5 MPa. The focused ultrasound allowed the release of the internal payload to localized regions within tissue phantoms. The vehicles showed high payload loading efficiency of 16%, stability in blood of several hours, and low level macrophage recognition in vitro. High speed fluorescent videos present the first optical images of such vehicles interacting with ultrasound. This ability to open the outer membrane in small regions of deep tissue could provide a second level of spatial and temporal control beyond biochemical targeting, making these particles promising for in vivo animal studies.     

钾离子浓度及离子通道电导对海马CA1区神经元自发放电的影响

目的 分析在胞外钾离子浓度[K+]0和离子通道电导变化的情况下,海马CA1区单个神经元自发放电频率和放电模式的变化.方法 对 Warman等提出的模型进行改进,应用计算机软件MATLAB建立一个包括16个房室的海马CA1区锥体细胞单个神经元的电缆模型.其中树突室不含有源通道,而胞体室含有5个离子通道(INa、INap、...     

前后联合入路治疗严重腰椎爆裂性骨折

目的 探讨前后联合入路治疗严重腰椎爆裂性骨折的疗效.方法 回顾性分析2000年2月至2006年12月收治并获得随访的34例严重腰椎爆裂性骨折患者,男31例,女3例;年龄23～48岁,平均35.4岁.损伤部位:L_1 10例,L_2 14例,L_3 6例,L_4 4例;骨折按AO分型均为A3型;脊髓神经损伤按Frankel分级:A级4例,B级10例,C级14例,D级6例.术前椎体前缘高度丢失37%～71%,平均丢失46.6%±5.1%;后凸Cobb角5°～45°,平均25.5°±3.1°;腰椎管骨块侵入占椎管矢状径百分比为57%～98%,平均72.5%±3.1%.其中采用一期前后路手术19例,分期前后路手术15例. 结果 手术时间3.5～5.0 h,平均4.3 h;术中出血1400～2200 mL,平均1700 mL;输血1000～1600 mL,平均1280mL.术后椎体前缘高度恢复至正常的95%～100%,平均98.6%;后凸Cobb角-11°～9°,平均-2.0°±1.1°,与术前比较差异均有统计学意义(P<0.05).29例椎管得到彻底减压,无骨折块占位,其余5例椎管侧方仍有少量骨块.所有患者随访11～84个月,平均42.5个月.最后随访时伤椎前缘高度及后凸Cobb无明显丢失,与术后比较差异无统计学意义(P>0.05).无假关节形成,未出现内固定松动、断裂现象.脊髓神经功能除4例A级无变化外,其余均有Ⅰ～Ⅲ级的恢复,最后恢复到C级2例,D级15例,E级13例. 结论 前后联合入路是治疗严重腰椎爆裂性骨折的有效方法 ,但应严格把握手术适应证.     

后路两种术式治疗胸腰椎爆裂性骨折临床效果对比

目的:比较后路两种术式治疗胸腰椎爆裂性骨折患者的临床疗效。方法:对54例胸腰椎爆裂性骨折患者的病例资料进行回顾性分析,按照治疗手段的不同分为两组:直接减压组24例,间接减压组30例,治疗后根据文中的指标进行评分,统计术后并发症,最后统计学方法检验两组患者治疗结果的差异性。结果:直接减压组生活能力评分(20.22±4.87)分,疼痛评分(34.43±7.22)分,3例出现术后并发症,间接减压组生活能力评分(31.25±5.02)分,疼痛评分(17.98±4.33)分,无术后并发症现象,与间接减压组有明显差异(P<0.05)。结论:间接减压法治疗胸腰椎爆裂性骨折具有显著的临床疗效。     

Femtosecond-UVA-riboflavin (FUR) cross-linking approach to penetrating keratoplasty and anterior lamellar keratoplasty

Purpose

To introduce femtosecond laser wound design combined with riboflavin/ultraviolet light-A (UVA) collagen cross-linking at the wound for penetrating (PKP) and anterior lamellar keratoplasty (ALK). Primary outcomes were intraocular pressure (IOP in mmHg) at burst point for the PKP group, and tensile strength (kPa) until dehiscence for the ALK group.

Methods

Human corneoscleral rims (N = 20) were mounted on artificial anterior chambers. PKP specimens underwent FUR, femtosecond laser-cut without cross-linking, or conventional corneal transplantation. PKP maximum burst IOP with progressive suture removal was assessed by a digital manometer, in triplicate and by three observers. ALK involved whole human globes (N = 10) divided into three groups using a 200-micron, 8 mm diameter donor lenticule, with or without cross-linking. Cross-linked specimens were exposed to UVA light (3 mW/cm² irradiance, 3.4 J, 370 nm wavelength) for 30 min with 0.1% riboflavin (20% Dextran) applied every 2-min. ALK tensile strength was determined using a digital tensiometer.

Results

In PKP, burst IOP was 31.32 mmHg greater for corneas that underwent the UVA-riboflavin treatment than for those that did not (p < 0.05). There was no significant relationship (p = 0.719) established between cut design (femtosecond versus conventional). On multivariate analysis, there was a mean of 15.82 mmHg higher sustainable pressure for each stabilization suture present (p < 0.0001). In ALK, specimens comprised of human donor and human recipient tissue combined with UVA-riboflavin therapy experienced the greatest level of adhesion strength (954.7 ± 290.4 kPa) as shown by the force required to separate the tissues, and compared to non-cross-linked specimens. Electron microscopy of ALK specimens showed non-fused and fused longitudinal cross-linked collagen fibers as well as bridges, densities, attachment plaques and primitive plasmalemmal densities.

Conclusions

Cross-linking effects of the FUR technique enable a stronger graft-recipient adhesion compared to conventional penetrating and anterior lamellar keratoplasty. Electron microscopy enabled visualization of cross-linked interface and potential bonding. The FUR approach may further lead to sutureless transplantation techniques in the future.

Setting/venue

ImagePlus Laser Eye Centre, Winnipeg, and University of Ottawa Eye Institute, Ottawa, Canada.     

两种植骨方式治疗L1椎体爆裂骨折的有限元研究

目的　建立L1椎体爆裂骨折的有限元模型,分析比较经椎弓根椎体内植骨和经椎管椎体内植骨的应力分布。 方法　通过CT扫描、Mimics三维重建、ANSYS前处理等方法建立胸腰段T12~L2有限元模型,据此建立L1椎体爆裂骨折后经椎弓根椎体内植骨和经椎管椎体内植骨加椎弓根钉棒后路固定模型。并对模型在前屈、后伸、侧弯和旋转下加载350N/8Nm,观察分析应力分布情况。 结果　正常胸腰段、L1椎体爆裂骨折、经椎弓根植骨和经椎管植骨模型的等效应力峰值如下,前屈：6.89、54.10、8.03、5.92 MPa;后伸：56.70、109.00、12.50、8.61 MPa;侧弯：6.83、47.50、11.30、3.60 MPa;旋转：23.80、112.00、13.10、7.65 MPa。未植骨时应力主要集中于螺钉的尾部和连接棒,植骨后应力明显降低,并向螺钉中部分散分布。 结论　两种植骨方式的模型均重建了伤椎的强度,增加即时稳定性,但经椎管椎体内植骨更充分、更有效减小内固定应力,增加其力学安全性,从生物力学角度是一种植得推广的术式。