生物可吸收性涂层补片的细胞毒性和遗传毒性研究

生物可吸收性涂层补片在应用于临床前必须进行一系列生物学评价以保证其安全性,细胞毒性和遗传毒性研究是其体外筛选部分。细胞毒性研究以补片浸提液接触受试细胞,观察细胞的毒性反应。生物可吸收性涂层补片浸提液1.5 cm2/ml时,细胞毒性反应1级;生物可吸收性涂层补片浸提液3 cm2/ml时,细胞毒性反应2级。遗传毒性研究包括两个试验,细菌回复突变试验结果表明生物可吸收性涂层补片的浸提液对鼠伤寒沙门氏菌受试株无致突变性;体外哺乳动物细胞染色体畸变试验中,任一处理组的细胞生长率均与阴性对照处于同一水平,表明没有诱导哺乳动物体细胞产生染色体畸变。     

羟基磷灰石涂层钛合金材料生物相容性研究初探

目的探讨一种新型的代骨材料--羟基磷灰石涂层的钛合金材料的生物相容性。方法制备羟基磷灰石涂层钛合金材料浸提液后,采用细胞毒性实验以观察实验样品浸提液对L929小鼠成纤维细胞的毒性反应;通过对小鼠尾静脉及腹腔注射试验样品浸提液后,观察其对小鼠的急性全身毒性反应;Ames实验及迟发型超敏反应实验对其遗传毒性及致敏性进行安全性评价。结果羟基磷灰石涂层钛合金材料浸提液对L929小鼠成纤维细胞的相对增殖率(RGR)为96.9%,细胞毒性反应为1级,无细胞毒性反应;对小鼠亦无明显的急性全身毒性作用,实验样品组与阴性对照组动物体质量差异无统计学意义(P0.05);遗传毒性Ames实验表明,在活化与非活化条件下,该材料浸提液对鼠伤寒沙门氏菌株的回变菌落数与对照组比均未增加2倍,对该菌株无诱变性;迟发型超敏反应实验显示,该材料浸提液无潜在的皮肤接触致敏性。结论羟基磷灰石涂层的钛合金材料具有良好的生物相容性。     

纳米TiO2:C薄膜涂层的生物相容性评价

背景：前期实验采用溶胶-凝胶法在纯钛片表面制备了纳米TiO₂:C薄膜涂层。 目的：评估纳米TiO₂:C薄膜涂层的生物相容性。 方法：①溶血实验：取新西兰大白兔静脉血,分别加到TiO₂-生理盐水、TiO₂:C-生理盐水、蒸馏水和生理盐水中。②细胞毒性实验：将TiO₂:C浸提液加入对数生长期的L929 细胞培养基中。③短期全身毒性实验：将60只BALB/C小白鼠随机分为3组,分别灌胃给予TiO₂浸提液、TiO₂:C浸提液及生理盐水。④口腔黏膜刺激实验：将牙胶圆片与TiO₂:C纳米薄膜涂片分别缝合固定于仓地鼠颊黏膜上。 结果与结论：纳米TiO₂:C涂层未引起急性溶血,毒性等级为0-1 级,未对细胞产生明显毒性,细胞周期未见明显异常;TiO₂:C浸提液对小鼠无短期全身毒性;对仓鼠口腔黏膜无刺激性。表明纳米TiO₂:C薄膜涂层具有良好的生物安全性。     

聚乳酸/纳米羟基磷灰石复合微球的生物安全性评价

背景：纳米材料以及包含纳米相的医疗器械,因为纳米材料具有尺寸小、比表面积大等独特特性,可能会引发特殊的生物效应,其生物安全性成为人们关注的重点。目的：评价聚乳酸/纳米羟基磷灰石复合微球的生物安全性。方法：采用乳液溶剂挥发法制备聚乳酸/纳米羟基磷灰石复合微球。(1)细胞毒性实验：将聚乳酸/纳米羟基磷灰石复合微球浸提液与小鼠成纤维细胞共培养,同时设置空白对照(完全培养基)、阴性对照(高密度聚乙烯树脂浸提液)与阳性对照(二乙基二硫代氨基甲酸锌浸提液),采用MTT法评价细胞毒性;(2)致敏反应：将复合微球分别进行极性浸提和非极性浸提,进行豚鼠皮内诱导和激发实验,记录结果;(3)皮内反应：将复合微球进行极性浸提和非极性浸提,兔皮内注射后即刻及24,48,72 h,观察各注射部位状况;(4)全身急性毒反应：将复合微球分别进行极性浸提和非极性浸提,通过静脉和腹腔注射到KM小鼠体内,观察小鼠体质量变化;(5)热源反应：将复合微球进行极性浸提,通过耳缘静脉注射至兔体内,记录体温变化;(6)骨植入实验：将圆柱状的复合微球与高密度聚乙烯棒分别植入兔胫骨缺损部位,进行大体观察和局部组织病理学观察。结果与结论：...     

新型医用无镍不锈钢的生物相容性评价

背景：BIOSSN4无镍不锈钢是一种奥氏体医用不锈钢材料,在中国药品生物制品检定所通过了标准的溶血实验、细胞毒性实验和致敏实验。 目的：评价新型医用BIOSSN4无镍不锈钢的体外细胞毒性及抗腐蚀性。 方法：将小鼠L929成纤维细胞悬液以1×108 L-1的浓度接种于96孔板,分5组培养,分别加入BIOSSN4无镍不锈钢浸提液、316L不锈钢浸提液、金合金浸提液、铅材料浸提液(阳性对照)及RPMI1640培养液(阴性对照)。培养1,2,3 d,观察细胞形态,采用MTT法检测各组吸光度值,计算细胞相对增殖率,评价毒性分级。在模拟口腔环境中,检测BIOSSN4无镍不锈钢、316L不锈钢及金合金的自腐蚀电位、自腐蚀电流密度及极化电阻。 结果与结论：培养3 d内,铅材料浸提液组细胞皱缩,细胞数量明显减少,细胞相对增殖率低于其余4组(P < 0.05);其余4组细胞形态良好,增殖旺盛,细胞相对增殖率均在75%以上。BIOSSN4无镍不锈钢浸提液、316L不锈钢浸提液与金合金浸提液的毒性均为1级,铅材料浸提液的毒性为2至3级,表明BIOSSN4无镍不锈钢具有良好的生物相容性。BIOSSN4无镍不锈钢的抗腐蚀性高于316L不锈钢,低于金合金。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

煅烧骨的安全性

背景：经高温处理的煅烧骨具有类似自然骨的连续微孔结构,良好的生物相容性和降解性。 目的：观察牛煅烧骨的生物相容性、细胞相容性及毒性。 方法：①细胞相容性实验：将牛煅烧骨与第3 代已诱导的Wistar大鼠骨髓间充质干细胞复合培养。②溶血实验：将煅烧骨浸提液、生理盐水与双蒸水加入兔血中。③凝血实验：将煅烧骨加入兔血浆中。④急性毒性实验：在昆明种小鼠尾静脉分别注射煅烧骨浸提液、生理盐水。⑤微核实验：在小鼠腹腔分别注射煅烧骨浸提液、生理盐水与环磷酰胺。⑥局部刺激性实验：将煅烧骨浸提液、生理盐水分别注射于兔两侧脊柱皮下。⑦热源检测实验：在兔耳静脉注射煅烧骨浸提液。⑧皮下植入实验：将煅烧骨材料植入Wistar大鼠背部皮下。 结果与结论：煅烧骨材料无细胞毒性,具有良好的细胞及血液相容性;对皮肤、肌肉无刺激作用;对心、肝、肾重要器官无毒性作用;皮下植入后对周围组织无刺激作用,能够部分降解吸收并被机体组织替代;无致热作用,对凝血功能无影响,对小鼠骨髓细胞无抑制及毒性作用。     

起搏器封装用环氧树脂材料的细胞毒性研究

对两种环氧树脂进行细胞毒性研究,探讨环氧树脂对L929成纤维细胞的细胞增殖影响,为其在植入式人工心脏起搏器的封装应用提供依据.按照GB/T 16886制备样品及材料的浸提液,在48 h、72 h、96 h对细胞生长状况进行拍照观察,并通过MTT方法,检测材料浸提液对成纤维细胞的细胞毒性作用,根据细胞相对增值率,对材料毒性进行分级.细胞在两种环氧树脂浸提液中生长正常,细胞形态良好,实验期内浸提液对成纤维细胞的相对增殖率均在90%以上,材料细胞毒性分级为0-1级.说明实验选用的两种环氧树脂与L929细胞相容性良好,无细胞毒性,符合心脏起搏器植入材料的细胞毒性要求.     

新型可注射可降解磷酸钙骨水泥的生物相容性

背景：体外实验已证实新型磷酸钙骨水泥有良好的可注射性、力学性能、抗溃散性及体外降解性能。 目的：验证新型可注射、可降解磷酸钙骨水泥的生物相容性。 方法：①急性毒性实验：分别向昆明小鼠尾静脉可注射新型磷酸钙骨水泥浸提液与生理盐水。②热源实验：在新西兰兔耳缘静脉注射新型磷酸钙骨水泥浸提液。③溶血实验：在兔抗凝血分别加入新型磷酸钙骨水泥浸提液、生理盐水及双蒸水。④迟发型超敏反应实验：在豚鼠肩胛骨内侧部位分别注射可注射新型磷酸钙骨水泥浸提液与生理盐水,并进行敷贴激发实验。⑤体外细胞毒性实验：在L929系小鼠成纤维细胞株培养液中分别加入可注射新型磷酸钙骨水泥浸提液、聚乙烯浸提液及苯酚溶液。⑥微核实验：分别在昆明小鼠腹腔注射可注射新型磷酸钙骨水泥浸提液、生理盐水与环磷酰胺。⑦肌肉植入实验：将新型磷酸钙骨水泥植入新西兰兔脊柱两侧肌肉内。 结果与结论：新型可注射磷酸钙骨水泥无毒,无刺激性及致敏性,无热源反应,具有良好的血液相容性,植入动物肌肉后为非组织刺激物,具有良好的生物相容性,因而具有较好的生物安全性。     

磁性壳聚糖微球的生物相容性

背景：采用壳聚糖对磁性氧化铁纳米颗粒表面进行改性,一方面可改善磁性纳米氧化铁颗粒的团聚性,增加其稳定性,另一方面将来可用于肿瘤热疗及基因治疗。 目的：制备将来可用于肿瘤热疗及基因治疗的磁性壳聚糖微球,评价其生物相容性。 方法：采用改良的化学沉淀法制备磁性氧化铁纳米颗粒。采用超声乳化法将壳聚糖加入到磁性氧化铁纳米颗粒中制备磁性壳聚糖微球,进行以下实验：①MTT实验检测磁性壳聚糖微球浸提液的细胞毒性：分别以1640培养液、聚丙烯酰胺单体溶液、100%,75%,50%,25%的磁性壳聚糖微球浸提液培养L-929细胞。②溶血实验：在兔抗凝血中分别加入磁性壳聚糖微球浸提液、生理盐水及蒸馏水。③微核实验：在昆明小鼠腹腔分别注射含氧化铁磁流体5,3.75,2.5,1.25 g/kg的磁性壳聚糖微球混悬液、环磷酰胺及生理盐水。 结果与结论：磁性壳聚糖微球粒径200-300 nm,分散效果有所提高。不同浓度的磁性壳聚糖微球浸提液对L-929 细胞毒性为1级,属对细胞无毒性范畴。磁性壳聚糖微球浸提液的溶血率为0.69%,小于5%,符合医用材料的溶血实验要求。磁性壳聚糖微球混悬液未导致细胞DNA断裂和非整倍体化,未导致微核产生的遗传毒理作用,材料无致畸或致突变作用,因此磁性壳聚糖微球具有良好的生物相容性。     

脱细胞软骨生物支架材料的生物学特性

目的 探讨脱细胞软骨生物支架材料（ACM）在细胞毒性、溶血试验、急性全身毒性等方面的生物学特性：方法①ACM的制备：猪膝关节软骨冻干加工为粉末，胰酶消化，曲拉通洗脱，蒸馏水洗净冻干，紫外线照射（UVI）后成型；③细胞毒性测定：材料浸提液培养细胞进行细胞形态人体观察，MTT法观察细胞活性；③急性全身毒性反应：材料浸提液注射入SD大鼠腹腔观察材料对动物表现及体重变化的影响；④溶血试验：材料浸提液与稀释动物鲜血混合观察红细胞溶解情况，492nm下检测OD值计算相对溶血率；结果 ①细胞毒性试验：24h、48h、72h各时间段内三组细胞OD值两两比较（P〉0．05），无显著差异，ACM细胞毒性为0级；②动物急性毒性实验：Ⅰ生物材料处理组和Ⅱ生理盐水处理组对动物体重影响没有差异（P〉0．05），Ⅰ生物材料处珊组和Ⅲ苯酚处理组对动物体重有显著差异（P〈0．05）；③溶血试验：材料相对溶血率为2.92％，低于5％的标准，尢明显溶血现象；结论ACM存细胞毒性、溶血实验、动物急性毒件反应方面符合软骨组织工程中对于支架材料的要求，提示支架材料何良好的牛物相容性和安全性。     

汽油和甲醇两种燃料的汽车尾气的TK基因突变试验比较

甲醇燃料极有希望成为更清洁的汽油替代品,然而有关甲醇燃料汽车尾气对健康影响的研究报道极少,更未见对甲醇和汽油两种燃料汽车尾气的遗传毒性进行比较研究。为此本课题在同样的车型,同样的工况条件下采集了甲醇尾气和汽油尾气,选用L 5 178Y细胞Thymidine kinase(TK)基因突变试验,在同样的剂量范围进行了两种尾气的遗传毒性检测,并与微核试验和彗星试验的结果进行了比较。结果显示,在33～133ml/ m l范围内,汽油尾气的遗传毒性强于甲醇尾气,但是甲醇尾气的细胞毒性强于汽油尾气;与微核试验和彗星试验比较证实,L 5 178Y细胞TK基因试验检测基因突变更加灵敏。     

Evidence for indirect involvement of thymidine kinase in excision repair processes in mouse cell lines

Wild-type cells and thymidine kinase-deficient clones from two mouse lymphoma cell lines, P388 and L5178Y, were compared for sensitivity to killing by the mutagens, ultraviolet irradiation (UV), ethyl methane sulfonate (EMS), and N-methyl-N-nitro-N-nitrosoguanidine (MNNG). Two out of three thymidine kinase-deficient P388 clones showed significantly enhanced sensitivity to killing by all three mutagens. This increased sensitivity to killing was also reflected in increased mutagenesis by the three mutagens. In the L5178Y cell line, wild-type cells showed little difference to two thymidine kinase-deficient clones in terms of mutagen sensitivity. This indicates that thymidine kinase may be significant for DNA repair processes in P388 but not in L5178Y cells. Unscheduled DNA synthesis (UDS) experiments were carried out on P388 and L5178Y wild-type cells and wild-type Friend leukemia cells (which are mutagen-sensitive when deficient in thymidine kinase). The UDS experiments showed the L5178Y cells were low in excision repair abilities relative to the P388 cells and the Friend cell clone. This indicates that the increased mutagen sensitivity in thymidine kinase-deficient P388 and clone 707 Friend cells may be due to thymidine kinase playing an indirect role in DNA excision repair, a process which is of little significance in the L5178Y cell line.     

Genotoxicity and toxicity of the potential cancer-preventive agent polyphenon E

The potential health benefits of green tea continue to attract public and scientific interests and are attributed in part to polyphenolic catechin constituents. Polyphenon E (Poly E) is a decaffeinated green tea catechin mixture containing about 50% epigallocatechin gallate and 30% other catechins. We evaluated the toxicity and genotoxicity of Poly E by using two in vitro assays: bacterial mutagenesis in a Salmonella typhimurium-E. coli assay and the L5178Y mouse lymphoma cell thymidine kinase (Tk) gene mutation assay. In addition, we used two in vivo genotoxicity assays: the mouse micronucleus assay and the Big Blue cII transgenic mouse mutation assay. Repeat-dose toxicity evaluations were performed in mice in parallel with the Big Blue transgenic mutation assays. No significant increases in the revertant colonies were found in the bacterial mutagenesis assay, but a significant increase in the mutant frequency (MF) at the Tk locus was observed in the mouse lymphoma test system. We observed toxicity in mice when Poly E was administered at doses of 2,000 mg/kg/day. Lower doses produced no significant increases in micronucleated erythrocytes in the bone marrow of Swiss-Webster mice and no significant increases in cII transgene MF in the liver, lung, or spleen compared with controls. These results indicate that Poly E, although toxic at high doses (2,000 mg/kg/day), poses minimal genotoxic concern. In addition, these studies highlight the importance of using both in vitro and in vivo systems in genetic toxicity screening of pharmaceuticals before they are administered to humans.     

Mutagenicity and clastogenicity of acrylamide in L5178Y mouse lymphoma cells

Acrylamide was tested without exogenous activation in L5178Y/TK+/- -3.7.2C cells for mutation at the thymidine kinase locus and for clastogenicity. Acrylamide gave a positive induced mutagenic response (approximately 70 mutants/10(6) survivors) when tested at 600-650 micrograms/ml. The highest dose tested (850 micrograms/ml) resulted in an induced mutant frequency of approximately 380 mutants/10(6) survivors (survival = 13%). Acrylamide induced almost exclusively small-colony mutants, indicating that it might be acting by a clastogenic mechanism. As predicted, acrylamide was clastogenic, inducing both chromatid and chromosome breaks and rearrangements. A clearly positive clastogenic response was observed at both the 750 micrograms/ml and 850 micrograms/ml doses, which showed 16 and 64 aberrations per 100 cells, respectively (background = 3 aberrations per 100 cells). These studies indicate that the L5178Y/TK+/- mouse lymphoma assay can detect some chromosomal mutagens (clastogens) that show little activity in other single gene mutation assays, the CHO/HPRT and Salmonella.     

Locked nucleic acid (LNA): Based single‐stranded oligonucleotides are not genotoxic

Over the last decade, single stranded oligonucleotides (ON) have gained increased attention as a new drug modality. Because the assessment of genotoxicity risk during early development of pharmaceuticals is essential, we evaluated the potential of locked nucleic acids (LNA)‐ONs to induce DNA damage in L5178Y tk^+/? cells both with the mouse lymphoma assay (MLA) and the micronucleus test (MNT). Further, the MLA was performed to assess gene and chromosome mutation over 3 and 24h (± metabolic activation). In addition, the MNT was performed to assess, in addition, a potential aneugenic liability. None of the experiments demonstrated a genotoxic effect for the five tested LNA‐ONs. We further show data from four proprietary LNA‐ONs tested in standard genotoxicity assays in vitro and partially in vivo, which were all negative. In addition, cellular and nuclear uptake of LNA‐ONs in L5178Y tk^+/? cells was demonstrated. Based on the results presented here as well as in the literature about other representatives of this class, we consider LNA‐ONs as generally not DNA reactive and question whether genotoxicity testing of this class of ONs should be required. This is in line with recent recommendation made by the OSWG that extensively assessed the genotoxicity of oligonucleotides. Environ. Mol. Mutagen. 58:112–121, 2017. © 2017 Wiley Periodicals, Inc.     

Characterization of the genotoxicity of nitrilotriacetic acid

The chelating agent nitrilotriacetic acid (NTA), classified as an epigenetic rodent carcinogen, was assessed in the in vivo rodent Comet assay on isolated kidney cells. Unexpected potent increases in DNA damage were obtained in both the short (3-6 hr) and long-term (22-26 hr) expression times after a single oral treatment at 1,000-2,000 mg/kg bw. NTA was assayed in the Ames test using TA1537, TA98, TA100, and TA102 tester strains, and in the in vitro micronucleus assay on L5178Y mouse lymphoma cells and on CTLL2 and CTLL2/Bcl2 cells coupled to the apoptosis measurement, both with and without metabolic activation by aroclor 1254-induced liver or kidney rat S9-mix. Whatever the S9 origin, neither genotoxicity nor apoptosis was detected, while a strong increase in the micronuclei formation was observed without S9 without any apoptosis induction. The direct genotoxicity of NTA was confirmed in the mouse lymphoma tk+/- gene mutation assay and in the chromosomal aberrations test on human lymphocytes. When tested in combination with an excess of Ca2+, NTA gave negative results on L5178Y mouse lymphoma cells in the in vitro Comet and micronucleus assays but still induced DNA damage on rat primary kidney cells. The higher sensitivity of renal cells to Ca2+ variations could explained the positive response observed in vivo. The carcinogenicity of NTA could be a consequence of the survival of kidney cells to intracellular variations of Ca2+, leading to a local and indirect genotoxicity. This suggests that threshold dose exists beyond which tumor-generating events will be displayed.     

Loss of P53 heterozygosity is not responsible for the small colony thymidine kinase mutant phenotype in L5178Y mouse lymphoma cells

The mouse lymphoma L5178Y Tk+/- 3.7.2C assay is a well-characterized in vitro system used for the study of somatic cell mutation. It was determined that this cell line has a heterozygous mutation in exon 5 of Trp53. Based on this assumption that the cell line is heterozygous for the Trp53 gene, it was postulated that the small colony thymidine kinase (Tk) mutant phenotype may be due to a newly induced mutation/deletion in both the Trp53 and Tk1 alleles. The resultant Tk-/- mutants would also be Trp53+/0 or Trp53+/+ and would lose their ability to grow at normal rates. Subsequently, we published our evaluation of the Trp53 status in L5178Y cells. This analysis included sequencing of Trp53 exon 4 and determined that the mouse lymphoma cell line has a mutation in both of the Trp53 alleles and, therefore, no wild-type Trp53 allele in either Tk+/- cells or Tk-/- mutants. Because the cells have no wild-type Trp53, it is not possible that the small colony phenotype results from a newly induced loss of both functional Trp53 and Tk. To determine whether small colonies might, however, include the deletion of both Trp53 and Tk we evaluated, using microsatellite marker analysis, a series of small colony mutants. We also utilized in situ hybridization to determine that the Trp53 alleles are, in fact, in their normal chromosome 11 location in Tk+/- 3.7.2C mouse lymphoma cells. From all of these analyses we can conclude that the small colony mutant phenotype is not caused by deletion of both Trp53 and Tk1.     

Genotoxic effects of p-aminophenol in chinese hamster ovary and mouse lymphoma cells: Results of a multiple endpoint test

p-Aminophenol (PAP), a metabolite of aniline and acetaminophen, has been reported to be mutagenic in the L5178Y mouse lymphoma assay, but not in the CHO/HGPRT assay. In the present study, the effects of PAP in these two cells lines were examined to determine if the difference in activity is related to an intrinsic difference in the cell lines. CHO and L5178Y ^+/? mouse lymphoma cells were treated with PAP for 4 hr and assayed for 3 genetic endpoints: gene mutation at the HGPRT or TK locus, respectively; chromosomal aberrations at approximately 20 hr after initiation of treatment; and single-stand DNA breaks as detected by the single cell electrophoresis assay immediately after treatment. All treatments were conducted in the absence of S9. There was a dose-related, significant increase in TFT-resistant mouse lymphoma cells at dose levels that reduced survival to ?=50% of concurrent controls. In CHO cells, however, there was no increase in thioguanine-resistant cells at dose levels that reduced cell survival to < 20%. These results are consistent with published reports on PAP. While the CHO cells were slightly more resistant to the toxic effects of PAP, the dose levels used in the two cell lines did not differ by more than 2-fold. At equivalent survival levels, PAP induced a significant (up to 20% aberrant cells) number of aberrations, primarily complex rearrangements, in both cell lines. In the single cell electrophoresis assay, there was a reproducible dose-related increase in cells with single-strand DNA breaks with both the L5178Y cells and the CHO cells. The induction of single-strand breaks and chromosome aberrations by PAP suggests that, mechanistically, PAP produces similar genetic damage in both CHO and L5178Y cell lines, but intrinsic differences between assay systems are responsible for the divergent gene mutation results. © 1995 Wiley-liss, Inc.     

Mutagenic screening of marker grenade dyes by the Salmonella reversion assay, L5178Y/TK+/- mouse lymphoma assay, and in vivo sister chromatid exchange analysis in mice

Two dyes (C.I. Solvent Yellow No. 33 and a mixture of C.I. Solvent Yellow No. 33 and C.I. Solvent Green No. 3) were tested for mutagenicity in the Salmonella reversion assay and the L5178Y/TK+/- mouse lymphoma assay, and also for sister chromatid exchange (SCE) induction in vivo in C57B1/6J mice. In addition, a greater than 99.9% pure sample of the yellow dye [2-(2'-quinolyl)-1,3-indandione] was tested with and without exogenous activation in the Salmonella reversion assay and the L5178Y/TK+/- mouse lymphoma assay. Neither C.I. Solvent Yellow No. 33 nor the C.I. Solvent Yellow No. 33 and Solvent Green No. 3 mixture was positive for inducing SCEs in vivo. All three dyes were tested in the standard plate incorporation test in seven Salmonella strains TA98, TA100, TA102, TA104, TA1535, TA1537, and TA1538. The dyes were negative with and without exogenous activation in TA98, TA1535, and TA1538. One test with TA1537 was positive with the greater than 99.9% purified yellow dye. All three dyes gave weakly positive results (less than a twofold increase) with S-9 in TA100 and were clearly positive in TA102 and TA104 both with and without S-9. They also induced mutation at the thymidine kinase locus in mouse lymphoma cells, produced both large- and small-colony trifluorothymidine-resistant mutants, and were clastogenic. The purified yellow dye was further tested for SCE induction in mouse lymphoma cells and was determined to give a slightly positive response in the presence of S-9.     

Mutagenicity and cytotoxicity of malonaldehyde in mammalian cells.

Malonaldehyde (MA), a lipid peroxidation product derived from polyunsaturated fatty acids, is cytotoxic to a murine L5178Y lymphoma cell line cultured in vitro. Exposure of cells for 24 hours to as little as 20 microM MA produced detectable cytotoxicity as well as an increased number of mutants among survivors, using thymidine or methotrexate resistance as genetic markers. The induced mutation frequency, within the range of MA concentrations tested (10-100 microM), is dose-dependent. Significant division delay, which results in unbalanced growth, is also observed in MA-treated cells. It is suggested that MA crosslinks with DNA and mutagenizes cells through the error-prone repair system. In order to relate the degree of mutagenicity of MA in reference to other mutagenic agents in mammalian cells, the mutation frequency of the thymidine-resistance marker in L5178Y induced by X-irradiation is also presented. The significance of lipid peroxidation in relation to carcinogenesis and the various theories of aging will be briefly discussed.