Safety evaluation of surgical materials by cytotoxicity testing

The cytotoxicity of three kinds of commercially available absorbable hemostats [oxidized cellulose (Surgicel, gauze and cotton types), microfibrillar collagen (Avitene), and cotton-type collagen (Integran)] and one adhesion barrier [sodium hyaluronate and carboxymethyl-cellulose membrane (Seprafilm)] were comparatively assessed by a colony assay using V79 cells and a minimum essential medium (MEM) elution assay in combination with a neutral red assay using L929 cells. Strong cytotoxicity was detected for Surgicel by both the MEM elution assay and the colony assay. For Avitene, both methods revealed weak cytotoxicity. For Seprafilm, no cytotoxicity was detected by the MEM elution assay, while a moderate degree of cytotoxicity was observed in the colony assay. For Integran cytotoxicity was not detected by either the MEM elution or the colony assay. The results of the different methods showed some inconsistency in terms of the degree of cytotoxicity of the materials. It is proposed that the combination of two or more sensitive cytotoxicity testing methods for the evaluation of biomaterials is necessary to avoid false-negative results for biomaterials at the preclinical stage. Furthermore, investigation of the correlation between the cytotoxicity and the extraction period of the surgical materials is helpful for predicting the effect of prolonged in vivo use of biomaterials on surrounding cells, tissues, and organs.     

荧光光谱法分析煤焦油组分

研究煤焦油组分时,为了防止组分相互之间的干扰,在测定前用几种不同极性的溶剂:石油醚;80%石油醚-20%甲苯;60%石油醚-40%甲苯;40%石滑醚-60%甲苯;20%石油醚-80%甲苯;甲苯;氯仿;50%氟仿-50%甲醇;甲醇进行洗提,从煤焦油中得到9个级分。然后用荧光法从9个级分中鉴定出28个组分:茶、苊、联苯、三甲基酚、菲、异喹啉、芴、对氨基酚、联苯胺、蒽醌、四氢萘、2,5-二甲酚、蒽、咔唑、间苯二酚、二乙基苯胺、喹啉、吲哚醌、1,3,5-三甲苯、1,2,4-三甲苯、萘醌、菲醌、窟、苾、氧芴、1,2-苯并蒽、2,3-苯并蒽、3,4-苯并苾。同时定量了氯仿和甲醇级分中氧芴、(艹屈)、联苯胺、苾、菲、蒽、咔唑、四氢蔡咔、四氢萘、苯醌、喹啉、8-羟基喹啉等12个组分的含量。     

国产洋红霉素对P388细胞单链DNA断裂及核仁超微结构的影响

用碱洗脱技术观察了国产洋红霉素（ＤＭＮ）引起小鼠淋巴白血病Ｐ３８８细胞单链ＤＮＡ的断裂作用。在ＣＭＮ０．２５－２．０μｇ／ｍｌ范围内,这种作用是剂量依赖性的。电镜观察研究ＣＭＮ对Ｐ３８８细胞核仁超微结构的影响。ＣＭＮ１．０μｇ／ｍｌ作用２小时,核仁空泡增多、微球体出现;作用４小时,核仁仁空增多、微球体出现;作用４小时,核仁“帽”形成;作用８小时,部分细胞核仁成分碎裂。     

葛根药材HPLC指纹图谱研究

目的 :对不同来源的葛根药材指纹图谱比较研究。方法 :应用RP HPLC法、Kromasil C₁₈分析柱、乙腈 水二元梯度洗脱 ,流速为 1.0mL·min^-1,检测波长 250nm。结果与结论 :不同来源的葛根药材所含黄酮类成分均得到很好的分离 ,该法可用于鉴别葛根的品种 ,并为葛根注射液及含葛根药材的中药复方注射液指纹图谱研究奠定基础。     

银黄胶囊质量标准研究

目的:建立银黄胶囊质量标准.方法:C1s柱(Hypersil ODS Agilent,4.6×200mm,5μm),流动相:甲醇与0.1%磷酸溶液进行梯度洗脱,检测波长为318mm,流速为1ml·min-1,柱温为室温.结果:绿原酸加样回收率为99.37%;RSD为0.35%;黄芩苷加样回收率为100.17%,RSD为1.23%.结论:方法简便、准确,可用于银黄胶囊的质量控制.     

HPLC-DAD法测定“武当三号金银花”不同部位中芦丁和木犀草苷的含量

目的：建立HPLC－DAD法测定“武当三号金银花”不同部位中芦丁和木犀草苷的含量。方法采用Fortis Xi Phenyl柱（250 mm ×4．6 mm,5μm）;流动相为乙腈（A）—0．5％冰醋酸溶液（B）进行线性梯度洗脱;检测波长为354 nm;柱温：30℃。结果芦丁和木犀草苷在各自测定的范围内均呈良好的线性关系（r≥0．9994）,平均回收率分别为99．4％、99．3％。结论该法操作简单,灵敏度高,重现性好,为控制“武当三号金银花”不同部位芦丁和木犀草苷的质量提供了一种可靠的方法。     

Mathematical Modeling of Crystallization Elution Fractionation of Ethylene/1‐Octene Copolymers

Crystallization elution fractionation (CEF) is a relatively new polyolefin characterization technique used to estimate the chemical composition distribution (CCD) of semicrystalline copolymers. CEF is developed to enhance the resolution and reduce the analysis time of temperature rising elution fractionation (TREF) by separating polymer samples in both the crystallization and elution steps. A model based on the concept of population balance, crystallization/dissolution kinetics, and dispersion model is developed to understand the CEF fractionation mechanisms. The proposed CEF model is found to describe well the experimental CEF profiles of a series of ethylene/1‐octene copolymers with different comonomer contents.

     

Genotoxic and cytotoxic effects of 4-aroyl-1-nitrosohydrazine-carboxamides onO 6-alkylguanine-DNA alkyltransferase-positive and-negative human cell lines

Five different representatives (I–V) of a new class of bifunctional alkylating agents, the 4-aroyl-1-nitrosohydrazinecarboxamides (nitrososemicarbazides), were evaluated for their potential interaction with DNA and for their cytotoxic activity in vitro toO ⁶-alkylguanine-DNA alkyltransferase-positive (Mer⁺) and-negative (Mer^–) human cell lines. The HeLa MR cell line (Mer^–) showed up to 20-fold higher sensitivity at IC₅₀ (dose that inhibits colony formation by 50%) to agents I–V than did the HeLa S3 cell line (Mer⁺) in a colony-formation assay. These data were compared to those obtained by treatment of the two cell lines with carmustine, a currently used antitumor drug. In Mer⁺ cells comparable results to those with carmustine were obtained with compounds III, IV and V; in Mer^– cells compounds I and II showed nearly the same effects as carmustine. Whether compounds I–V produce DNA strand breaks and/or DNA-protein cross-links was investigated using an alkaline filter elution technique. In this assay all compounds produced DNA single-strand breaks; no correlation could be detected between the strand breakage frequency and cytostatic, mutagenic and antitumor activity.Abbreviations Carmustine 1,2-bis-(2-chloroethyl)-1-nitrosourea - lomustine 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea - IC₅₀ dose that inhibits colony formation by 50% - PC polycarbonate - HVLP polyvinylidene fluoride     

Transmural atrial pacing in patients with postoperative congenital heart disease

INTRODUCTION: Some patients with postoperative congenital heart disease require permanent cardiac pacing, but the use of transvenous or epicardial pacing leads may be limited by type of cardiac malformation, venous connections, body size, or fibrosis. Transmural atrial pacing may provide an alternative in difficult patients, but to date has been described in only a few articles with small patient numbers, and data from lead performance are lacking. METHODS AND RESULTS: Records were reviewed in 18 consecutive patients (4 months to 21 years old) with postoperative congenital heart disease receiving transmural atrial pacing leads from July 1994 to December 1996. Implantation materials and techniques were described. Lead sensing and capture thresholds obtained acutely and during short-term follow-up (mean: 11.0 months) were evaluated, and comparisons were made between patients with postoperative Fontan anatomy and non-Fontan patients, and between patients receiving steroid-eluting and nonsteroid leads. Overall, the median acute sensing and capture thresholds of transmural leads were 4.1 m V and 0.7 V at 0.5 msec, respectively. Median follow-up thresholds were 2.8 m V and 0.8 V, respectively. Performance of leads in Fontan patients was similar to those in non-Fontan patients. Steroid-eluting leads had a chronic capture threshold of 0.6 V versus 0.9 V for nonsteroid leads (P = 0.038). CONCLUSION: Transmural atrial pacing leads were successfully implanted in patients with diverse ages and types of postoperative congenital heart disease. Lead performance was acceptable both acutely and during the first year of follow-up.