Molecular basis of hereditary methaemoglobinaemia, types I and II: two novel mutations in the NADH-cytochrome b5 reductase gene

Hereditary methaemoglobinaemia, caused by deficiency of NADH-cytochrome b₅ reductase (b5R), has been classified into two types, an erythrocyte (type I) and a generalized (type II). We analysed the b5R gene of two Thai patients and found two novel mutations. The patient with type II was homozygous for a C-to-T substitution in codon 83 that changes Arg (CGA) to a stop codon (TGA), resulting in a truncated b5R without the catalytic portion. The patient with type I was homozygous for a C-to-T substitution in codon 178 causing replacement of Ala (GCG) with Val (GTG). To characterize effects of this missense mutation, we investigated enzymatic properties of mutant b5R (Ala 178 Val). Although the mutant enzyme showed normal catalytic activity, less stability and different spectra were observed. These results suggest that this substitution influenced enzyme stability due to the slight change of structure. In conclusion, the nonsense mutation led to type II because of malfunction of the truncated protein. On the other hand, the missense mutation caused type I, due to degradation of the unstable mutant enzyme with normal activities in patient's erythrocytes, because of the lack of compensation by new protein synthesis during the long life-span of erythrocytes.     

The Role of Low Density Lipoprotein Apheresis in the Treatment of Familial Hypercholesterolemia

Abstract: The chief indication for low density lipoprotein (LDL) apheresis is the treatment of homozygous familial hypercholesterolemia (FH), a potentially fatal condition that responds poorly to conventional therapy. Dextran sulfate/cellulose adsorption columns (Kaneka) and on-line heparin precipitation (HELP) are the most popular systems used in LDL apheresis. Weekly or biweekly procedures plus concomitant drug therapy enable LDL cholesterol to be maintained at 30–50% of its untreated level, with regression of xanthomas, arrest of progression of coronary atherosclerosis, and improved life expectancy. However, aortic stenosis may progress despite apheresis and necessitate valve replacement. Better control of hypercholesterolemia results from combining apheresis with a new 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, atorvastatin. LDL apheresis can also be useful in treating drug-resistant FH heterozygotes with coronary disease. However, the FH Regression Study showed no evidence that reduction by apheresis of both LDL and lipoprotein(a), was more advantageous than reduction by combination drug therapy of LDL alone.     

阿托伐他汀钙对EA.hy926细胞全基因表达谱的影响及生物信息学分析

目的探讨阿托伐他汀钙对体外培养人脐静脉内皮细胞EA.hy926细胞基因表达谱的影响及作用的分子机制。方法取EA.hy926细胞分实验组和对照组,实验组采用10μmol/L阿托伐他汀钙体外干预人脐静脉内皮细胞EA.hy926 24h,用Affymetrix HG-U133plus 2.0全基因组表达芯片检测阿托伐他汀钙对EA.hy926细胞基因表达谱的影响。并运用基因富集分析(GSEA)软件、DAVID基因功能聚类分析软件及Cmap数据库对芯片数据进行分析,对相关靶基因进行实时定量PCR验证。结果与对照组比较,实验组基因芯片分析筛选出差异表达倍数>2倍的基因649个,其中上调基因295个,下调基因354个。经DAVID及GSEA基因富集分析显示,阿托伐他汀钙广泛下调了细胞周期调控相关基因,上调了Kruppel样转录因子等血管保护基因,Cmap数据库分析显示,阿托伐他汀钙与组蛋白去乙酰化酶抑制剂及白藜芦醇呈正相关的联强度高。结论阿托伐他汀钙从多角度发挥抗动脉粥样硬化作用,作用机制可能与组蛋白去乙酰化酶抑制剂及白藜芦醇相似。     

瑞舒伐他汀与阿托伐他汀治疗老年高脂血症患者临床疗效的比较

目的探讨瑞舒伐他汀治疗老年高脂血症患者的疗效和安全性,并与阿托伐他汀进行比较。方法选择2012年6¹2月在我院门诊干部诊疗科就诊的老年患者128例,随机分为瑞舒伐他汀组64例(瑞舒伐他汀5mg/d)和阿托伐他汀组64例(阿托伐他汀10mg/d),共治疗8周。2组患者继续原发病的常规治疗,停用其他调脂药物2周,以减少对疗效判断的干扰。结果治疗8周后,瑞舒伐他汀组TC、TG和LDL-C下降幅度分别为25.9%、13.5%和33.7%,阿托伐他汀组下降幅度分别为22.6%、12.1%和31.4%,2组下降幅度比较,差异无统计学意义(P>0.05)。瑞舒伐他汀组与阿托伐他汀组HDL-C上升幅度差异有统计学意义(9.7%vs 3.2%,P<0.05)。2组患者对药物的依从性好,无药物不良反应。结论瑞舒伐他汀5mg与阿托伐他汀10mg在降低TC、TG及LDL-C方面相似;瑞舒伐他汀可提高HDL-C水平,且在老年患者中两者安全性相同。     

Mutation of alkyl hydroperoxide reductase gene ahpC of Xanthomonas oryzae pv. oryzae affects hydrogen peroxide accumulation during the rice–pathogen interaction

Hydrogen peroxide (H₂O₂) is usually generated by normal aerobic respiration of pathogens and by the host defense response during plant–pathogen interactions. In this study, histochemical localization of H₂O₂ accumulation in rice inoculated with the wild-type strain (PXO99^A) and the gene deletion mutant (ΔahpC) of alkyl hydroperoxide reductase subunit C (AhpC) of Xanthomonas oryzae pv. oryzae (Xoo), the bacterial blight pathogen of rice, was analyzed. The ΔahpC mutant displayed a significant decrease in endogenous H₂O₂ accumulation which was induced by the compensatory increase in H₂O₂ scavenging activity. The change in the bacterial endogenous H₂O₂ level affected the total amount of H₂O₂ accumulation during the interaction with rice plants. These results suggested that Xoo contributes to H₂O₂ accumulation in rice in a compatible interaction, and pathogen-driving H₂O₂ is in association with cell collapse of rice.     

急性淋巴细胞白血病患儿MTHFR C677T基因多态性与大剂量甲氨蝶呤治疗后肝功能异常的相关性

目的：探讨急性淋巴细胞白血病（ALL）患儿亚甲基四氢叶酸还原酶（MTHFR）C677T基因多态性与大剂量甲氨蝶呤（HD-MTX）治疗后肝功能异常的相关性。方法：收集2017年10月至2020年3月温州医科大学附属第二医院育英儿童医院66例ALL患儿HD-MTX治疗的临床资料,检测MTHFR C677T的基因多态性,根据基因型将患儿分为野生型（CC）和突变型（CT+TT）,比较2组患儿经HD-MTX治疗后不良反应的发生率、肝功能指标PA、ALT、AST、AST/ALT、TP、ALB、LDH、GGT、TBIL、CHE以及48 h、72 h血药浓度的差异。结果：MTHFR C677T突变型与野生型相比肝功能异常的发生率更高（P＜0.05）,其中血清AST、ALT、CHE含量异常的患儿比例显著升高（P＜0.05）,其他肝功能指标差异无统计学意义（P＞0.05）。进一步分析不同基因型患儿HD-MTX血药浓度的差异,结果显示与野生型相比,突变型48 h、72 h血药浓度均升高（P＜0.05）。结论：MTHFR C677T突变型患儿HD-MTX治疗后,血清AST、ALT、CHE含量异常的患儿比例较高,检测MTHFR C677T基因型对预测HD-MTX治疗后肝功能异常有一定的临床应用价值。