Porous Polyethylene Implants for Nasal Reconstruction: Clinical and Histologic Studies

This paper describes a technique of using Medpor porous high-density polyethylene implants for nasal reconstruction and chin augmentation. This biocompatible material has been used successfully during the last decade for various applications in the reconstruction of the facial skeleton. Among its most frequent uses are repair of the orbital floor and reconstruction of the burned ear, which became standard methods at many centers. Relatively little experience is, at present, on hand concerning the use of porous polyethylene in reconstruction of the nasal framework. Twenty-three consecutive, difficult nasal reconstructions were performed using this method since 1996. Patients were followed up for from 1 to 3 years (mean, 2 years). The results were durable and stable over the time. Eight patients had saddle nose deformity and 15 had catastrophe noses, mostly referrals, previously operated on from one to four times. My aesthetic goals were correction of the depressed nasal dorsum, creation of an acceptable nasal dorsum in the thick and/or twisted noses, and tip elevation. For nasal applications Medpor is available as a strut or sheet. Its body, once implanted, becomes rapidly vascularized and both soft tissue ingrowth and collagen deposition occur. This was confirmed by the microscopic investigation of biopsies. One patient of Vietnamese origin had an aesthetically pleasing result, but her family refused to accept her westernized nose. This gave me a unique opportunity to study the whole Medpor implant 6 months after implantation. There were two complications, one small implant exposure and one low-virulent infection involving the nasal tip. Following revision and antibiotic treatment, both patients healed without sequel. All reconstructions were successful in restoring nasal aesthetics and function. Four patients underwent chin augmentations with an uneventful clinical course.     

Degradation Kinetics of BMP 777, an Elastase Inhibitor

Purpose. The objective was to evaluate the degradation profile of the elastase inhibitor DMP 777 and lay the foundation for formulation development. Methods. The pK_a was determined by potentiometric titration in mixed-aqueous solvents. The degradation kinetics were studied as a function of pH, buffer concentration, ionic strength, methanol concentration and temperature using a stability-indicating HPLC assay. The degradation products were identified by LC-MS, NMR, and by comparison with authentic samples. Results. The pK_a for the protonated piperazine nitrogen was estimated to be 7.04. The pH-rate profile is described by specific acid-, water-, and specific base-catalyzed pathways. The pH of maximum stability is in the range of 4 to 4.5 where water is the principal catalyst in the reaction. Buffer catalysis, primary salt effects and medium effects were observed. The proposed mechanism for acid catalyzed degradation is the rarely observed A_AL1 which involves alkyl-nitrogen heterolysis. The driving force for the reaction appears to lie in the stability of the benzylic carbocation. The proposed mechanism for base catalyzed degradation is B_AC2 which involves -lactam ring opening. The -lactam ring of DMP 777, a monolactam, appears to be as reactive as that in benzylpenicillin in the k _OH controlled region where a similar mechanism of hydrolysis should be operative. A contributing factor to this increased reactivity may lie in the reduced basicity of the -lactam nitrogen making it a good leaving group. Conclusions. The degradation profile indicates that development of a solution dosage form of DMP 777 with adequate shelf-life stability at room temperature is feasible.     

Stability of aztreonam in a portable pump reservoir used for home intravenous antibiotic treatment (HIVAT)

The stability of the monocyclic -lactam antibiotic aztreonam in portable pump reservoirs was studied during storage at temperatures of-20°C and +5°C and during drug delivery at 37°C. Three 100-ml drug reservoirs and three glass containers containing 60 mg/ml aztreonam were stored at-20°C and 2-ml samples were analysed in the freshly prepared solution and after thawing at days 7, 21, 28, 70 and after 6 months of storage. A separate triplicate batch of 100-ml prefilled drug reservoirs and glass containers containing a similar aztreonam concentration (60 mg/ml) were refrigerated and tested immediately after preparation and daily for 8 days and after 70 days. Solutions of aztreonam in duplicate freshly prepared reservoirs were tested for stability when the solution was pumped at 37°C over a 24-h period. All solutions were inspected for visual changes and tested for pH. Drug concentration was analysed by high-performance liquid chromatography. No colour changes or pH differences were observed in any of the solutions in the reservoirs or containers. No statistically significant decrease in aztreonam concentration could be detected after 6 months of storage at-20°C. Aztreonam was stable at 5°C for at least 8 days. A 24-h pumping period at 37°C showed a 3.6% decrease in aztreonam concentration. Aztreonam at a concentration of 60 mg/ml in a pump reservoir is sufficiently stable to be used in home intravenous antibiotic treatment programmes.     

Stability of Interleukin 1β (IL-1β) in Aqueous Solution: Analytical Methods,Kinetics, Products,and Solution Formulation Implications

The thermal stability of IL-1 in aqueous solution as a function of temperature (5–60°C), pH (2–9), buffer (acetate, citrate, tris, and phosphate), and cyroprotectants (sugars, HSA) was investigated in this study. The analytical methodologies included RP-HPLC, SEC, ELISA, IEF-PAGE, SDS-PAGE, and bioassay. The degradation and inactivation of IL-1 at or above 39°C were attributed to autoxidation of the two cysteine residues in the denatured protein, followed by hydrophobic/covalent aggregation and precipitation. At or below 30°C, IEF- and SDS-PAGE results suggest a possible deamidation reaction. The difference in mechanism of degradation precludes the prediction of formulation shelf life from accelerated temperature data. Nonetheless, the good stability observed at 5°C suggests that a solution formulation may be feasible for IL-1.     

冰醋酸涂剂稳定性研究

目的：研究冰醋酸涂剂的稳定性。方法：采用酸碱中和分析法和气相色谱法分别对醋酸与其不稳定产物乙酸乙酯运行定量测定。结果：在放置过程中醋酸含量下降，而乙酸乙酯含量增加。结论：《中国医院制剂规范》第2版收载的冰醋酸涂剂不稳定。     

喷雾干燥对溶菌酶一级结构的影响

目的 考察喷雾干燥对溶茵酶一级结构稳定性的影响。方法 以送料速度2.4 ml/min、进口气流温度150℃、出口气流温度70℃、雾化器转速18 000 r/min制备喷雾干燥溶茵酶。采用MALDI-TOF/MS测定喷雾干燥对溶菌酶一级结构的影响。结果 喷雾干燥溶菌酶除了具有溶菌酶相同的准分子离子峰、二聚体、三聚体、四聚体及三聚体的两电荷离子峰外,另多5个碎片离子峰。结论 喷雾干燥可造成溶菌酶一级结构破坏。     

直电极与弯电极序列人工耳蜗植入深度的比较

目的测量比较Nucleus CI 24M直电极序列和CI24 Contour弯电极序列两种型号植入体的电极植入深度。方法对41例CI 24M和8例CI 24 Contour植入者,术后拍摄耳蜗位X线平片。应用图像处理技术,比照耳蜗螺旋模板,建立电极序列的极坐标图形,测量第22号电极与耳蜗开窗处的极坐标角度,两者之差代表了电极序列的植入深度。以t检验比较两种型号植入体的植入深度状况。结果 无内耳畸形、手术条件相当的情况下,CI 24 Contour植入体的平均插入角度为413°,CI 24M植入体的平均插入角度为316°,P=0.0001。结论CI 24 Contour植入体的植入深度明显深于CI 24M。前者更有利于医师进行植入。     

阿昔洛韦软膏的稳定性研究

目的 :建立阿昔洛韦软膏高效液相色谱测定方法 ,考察该制剂的稳定性。方法 :采用高效液相色谱法测定软膏中阿昔洛韦的含量 ,考察湿度、光照及温度对阿昔洛韦软膏稳定性的影响。结果 :标准曲线方程为C=9 310×10-3A +0 159 ,r=0 9999(n=6) ;线性浓度范围为0 6～19 2μg/ml ;回收率为98 51 % ,RSD=0 42 %。阿昔洛韦软膏对湿度和强光照射不敏感 ;于40℃、60℃和80℃温度下放置10d ,其标示量分别为98 36 %、98 47 %和98 26 %。结论 :建立的方法具有简便、快速和准确度高等优点 ;该制剂对强光照射不敏感 ,室温保存稳定。     

盐酸乌拉地尔(利喜定)注射液与临床常用5种药物的配伍稳定性考察

目的 :考察盐酸乌拉地尔注射液分别与氯化钾、门冬氨酸钾镁、碳酸氢钠、维生素C、盐酸利多卡因5种注射液的配伍稳定性。方法 :采用紫外分光光度法考察各配伍液在室温条件下 (15℃～25℃ )配伍0h～8h内吸收度、吸收曲线变化 ,测定 pH值 ,同时观察其外观和普通显微镜下的变化。结果 :盐酸乌拉地尔注射液在10 %葡萄糖输液中分别与以上5种注射液混合配伍后 ,pH值、外观、普通显微镜下及紫外吸收光谱各项检查均无变化。结论 :盐酸乌拉地尔注射液分别与以上5种注射液配伍稳定。     

眼镜蛇毒高活性抗补体因子的体外溶血活性研究

目的　了解云南孟加拉眼镜蛇毒高活性抗补体因子的体外溶血活性。方法　采用由豚鼠血清、豚鼠红细胞和该抗补体因子组成的体外溶血体系 ,对其溶血活性、溶血活性稳定性以及多种二价金属离子、EDTA对其溶血活性的影响进行研究。结果　该抗补体因子溶血活性的比活力为 1 391KU·g- 1 ,其溶血活性对温度、酸碱表现出较好的稳定性 ,1、2、5mmol·L- 1 的Ca2 + 、Mg2 + 、Mn2 + 能促进抗补体因子的溶血活性 ,1、2mmol·L- 1 的Zn2 + 、Co2 + 能促进抗补体因子的溶血活性 ,而 5mmol·L- 1 的Zn2 + 、Co2 + 则抑制抗补体因子的溶血活性 ,Cu2 + 在 1、2、5mmol·L- 1 时则强烈抑制抗补体因子的溶血活性 ,EDTA能强烈抑制抗补体因子的溶血活性。结论　云南孟加拉眼镜蛇毒高活性抗补体因子具有一定的溶血活性 ,并且具有较好的温度耐受性及酸碱稳定性。多种二价金属离子及EDTA能促进或抑制这种溶血活性