Genetic toxicity assessment using liver cell models: past,present, and future

ABSTRACT

Genotoxic compounds may be detoxified to non-genotoxic metabolites while many pro-carcinogens require metabolic activation to exert their genotoxicity in vivo. Standard genotoxicity assays were developed and utilized for risk assessment for over 40 years. Most of these assays are conducted in metabolically incompetent rodent or human cell lines. Deficient in normal metabolism and relying on exogenous metabolic activation systems, the current in vitro genotoxicity assays often have yielded high false positive rates, which trigger unnecessary and costly in vivo studies. Metabolically active cells such as hepatocytes have been recognized as a promising cell model in predicting genotoxicity of carcinogens in vivo. In recent years, significant advances in tissue culture and biological technologies provided new opportunities for using hepatocytes in genetic toxicology. This review encompasses published studies (both in vitro and in vivo) using hepatocytes for genotoxicity assessment. Findings from both standard and newly developed genotoxicity assays are summarized. Various liver cell models used for genotoxicity assessment are described, including the potential application of advanced liver cell models such as 3D spheroids, organoids, and engineered hepatocytes. An integrated strategy, that includes the use of human-based cells with enhanced biological relevance and throughput, and applying the quantitative analysis of data, may provide an approach for future genotoxicity risk assessment.     

放射性心脏损伤动物模型相关实验研究进展

当利用放射线对胸部恶性肿瘤进行治疗时，位于纵隔的心脏会不可幸免受到照射，从而诱发放射性心脏损伤（radiation-induced heart disease, RIHD）。随着手术以及放化疗技术的提升，肿瘤患者生存时间得到延长，使得RIHD这一放疗远期并发症被越来越多的报道。因此，学者们对于RIHD的研究逐渐升温。目前国内外学者关于该疾病尚未形成统一的认识，临床上缺乏有效阻止其发生的方法。动物模型研究可为临床该疾病治疗及预防提供可靠证据，为此本文回顾分析近年来放射性心脏损伤动物模型实验研究情况，旨在为后续实验开展及临床应用提供参考。     

Endodontic treatment of a hypertaurodontic mandibular left second molar in a patient with many taurodonts combined with multiple pulp stones

Taurodontism is a rare embryologic anomaly of teeth, defined by an apical displacement of the furcation of roots and enlarged pulp chambers. Taurodontism has been classified as hypo‐, meso‐ or hypertaurodontism according to the severity of the anomaly. The aim of this case report was to illustrate a clinical case with multiple bilateral taurodonts and to describe the endodontic management of the hypertaurodontic mandibular left second molar with a C‐shaped canal and extensive dental pulp calcifications. A healthy 20‐year‐old male patient was referred for the endodontic treatment of his lower left second molar. Cone beam computed tomography revealed a C‐shaped root canal configuration and several dental pulp calcifications in this tooth. The endodontic treatment was performed in two appointments under an operating dental microscope. A panoramic radiograph, made during the 18 months follow‐up appointment, revealed nine other taurodontic molars, most of them associated with dental pulp calcifications.     

金水宝片联合依诺肝素对维持性血液透析患者血脂代谢的影响

目的：探究金水宝片联合依诺肝素对维持性血液透析患者血脂代谢的影响。方法：选取2018年12月至2019年3月马鞍山十七冶医院血液净化中心进行透析的患者154例作为研究对象，根据用药不同分为对照组和观察组,每组77例。对照组常规应用依诺肝素抗凝，观察组在对照组抗凝基础上加用金水宝片，各组均干预3个月，比较2组患者血脂变化及持续血液透析并发症发生情况。结果：治疗后，观察组患者三酰甘油、总胆固醇及低密度脂蛋白胆固醇水平下降，高密度脂蛋白胆固醇升高，与治疗前比较差异均有统计学意义（P<0.05），与对照组治疗后比较，差异有统计学意义（P<0.05）；观察组总并发症发生率明显低于对照组，2组比较差异有统计学意义（P<0.05）；2组患者维持性血液透析不良反应发生率均较低，组间比较差异无统计学意义（P>0.05）。结论：金水宝片联合依诺肝素有助于改善维持性血液透析患者血脂代谢水平，降低维持性血液透析相关并发症，值得临床推广应用。     

Protein kinase Cδ mediates trimethyltin-induced neurotoxicity in mice in vivo via inhibition of glutathione defense mechanism

We investigated whether protein kinase C (PKC) is involved in trimethyltin (TMT)-induced neurotoxicity. TMT treatment (2.8 mg/kg, i.p.) significantly increased PKCδ expression out of PKC isozymes (i.e., α, βI, βII, δ, and ?) in the hippocampus of wild-type (WT) mice. Consistently, treatment with TMT resulted in significant increases in cleaved PKCδ expression. Genetic or pharmacological inhibition (PKCδ knockout or rottlerin) was less susceptible to TMT-induced seizures than WT mice. TMT treatment increased glutathione oxidation, lipid peroxidation, protein oxidation, and levels of reactive oxygen species. These effects were more pronounced in the WT mice than in PKCδ knockout mice. In addition, the ability of TMT to induce nuclear translocation of Nrf2, Nrf2 DNA-binding activity, and upregulation of γ-glutamylcysteine ligase was significantly increased in the PKCδ knockout mice and rottlerin (10 or 20 mg/kg, p.o. × 6)-treated WT mice. Furthermore, neuronal degeneration (as shown by nuclear chromatin clumping and TUNEL staining) in WT mice was most pronounced 2 days after TMT. At the same time, TMT-induced inhibition of phosphoinositol 3-kinase (PI3K)/Akt signaling was evident, thereby decreasing phospho-Bad, expression of Bcl-xL and Bcl-2, and the interaction between phospho-Bad and 14-3-3 protein, and increasing Bax expression and caspase-3 cleavage were observed. Rottlerin or PKCδ knockout significantly protected these changes in anti- and pro-apoptotic factors. Importantly, treatment of the PI3K inhibitor LY294002 (0.8 or 1.6 µg, i.c.v.) 4 h before TMT counteracted protective effects (i.e., Nrf-2-dependent glutathione induction and pro-survival phenomenon) of rottlerin. Therefore, our results suggest that down-regulation of PKCδ and up-regulations of Nrf2-dependent glutathione defense mechanism and PI3K/Akt signaling are critical for attenuating TMT neurotoxicity.     

软组织损伤引起慢性疼痛的治疗

目的：综述运动系统软组织损伤引起慢性疼痛的各种治疗方法的研究进展。资料来源：应用计算机检索Medline1980—01／2006—04与运动系统软组织损伤引起慢性疼痛的治疗相关文章，检索词“Soft tissue injury，pain．chronic，comprehensive therapy”，并限定文章语言种类为“English”；同时计算机检索中国期刊全文数据库1994—01／2006-04期间的相关文章，检索词“软组织损伤、慢性疼痛、治疗方法”，并限定语言种类为中文。同时手工查阅相关书籍。资料选择：对资料进行初审，所选文献内容符合：①软组织损伤引起的慢性疼痛药物治疗的研究。②软组织损伤引起的慢性疼痛微创治疗的研究。③软组织损伤引起的慢性疼痛运动疗法的研究。④软组织损伤引起的慢性疼痛心理治疗的研究。⑤软组织损伤引起的慢性疼痛其他疗法的研究。排除重复性研究的文献。资料提炼：共收集到40篇关于软组织损伤引起的慢性疼痛治疗方法的文献，均为全文，23篇符合纳入标准，排除17篇重复性研究。同时录入书籍3本。资料综合：软组织损伤引起的慢性疼痛的产生是生理、心理及社会因素复杂结合的结果，个体表现差异较大，目前尚无特效治疗方法，常用的治疗方法有：药物治疗、微创治疗、运动疗法、心理治疗、物理疗法及其他疗法。结论：对于软组织损伤引起的慢性疼痛的治疗必须以整体的观点对其进行合理的评估和个体化治疗，才能收到良好的效果。     

Soluble triggering receptor expressed on myeloid cells-1 in acute respiratory infections.

Levels of the soluble form of the triggering receptor expressed on myeloid cells (sTREM)-1 are elevated in severe sepsis. However, it is not known whether sTREM-1 measurements can distinguish milder bacterial infections from noninfectious inflammation. The present authors studied whether serum sTREM-1 levels differ in community-acquired pneumonia, exacerbations of chronic obstructive pulmonary disease (COPD), asthma and controls, and whether sTREM-1 may be used as a surrogate marker for the need for antibiotics. Serum sTREM-1 levels in 150 patients with pneumonia, COPD and asthma exacerbations and 62 healthy controls were measured. Serum sTREM-1 levels were significantly elevated in pneumonia (median 295.2 ng x mL(-1)), COPD (280.3 ng x mL(-1)) and asthma exacerbations (184.0 ng x mL(-1)) compared with controls (83.1 ng x mL(-1)). Levels were higher in pneumonia and Anthonisen type 1 COPD exacerbations than in type 2 and 3 COPD and asthma exacerbations. The area under the receiver operating characteristics curve for sTREM-1 as a surrogate marker for the need for antibiotics was 0.77. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 were elevated predominantly in pneumonia and Anthonisen type 1 COPD exacerbations versus type 2 and 3 chronic obstructive pulmonary disease exacerbations, asthma and controls. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 has moderate but insufficient accuracy as a surrogate marker for the need for antibiotics in lower respiratory tract infections.