动脉粥样硬化性脑梗死患者血浆同型半胱氨酸水平及亚甲基四氢叶酸还原酶基因多态性

目的 探讨血浆同型半胱氨酸水平、亚甲基四氢叶酸还原酶基因多态性与动脉粥样硬化性脑梗死之间的关系.方法 选择性别、年龄匹配的动脉粥样硬化性脑梗死患者(脑梗死组)68例及对照组50例,采用荧光偏振免疫法测定血浆同型半胱氨酸水平,聚合酶链反应-限制性片长多态性技术检测亚甲基四氢叶酸还原酶基因多态性.结果 脑梗死组TT基因型(36.8%比16.0%)及T等位基因频率(59.6%比38.0%)均显著高于对照组(P<0.05).脑梗死组血浆同型半胱氨酸水平显著高于对照组(P<0.05).脑梗死组和对照组亚甲基四氢叶酸还原酶 677TT纯合子血浆同型半胱氨酸水平均显著高于CT型和CC型者(P<0.05).结论 血浆同型半胱氨酸水平升高是动脉粥样硬化性脑梗死的危险因素.亚甲基四氢叶酸还原酶 C677T基因多态性与血浆同型半胱氨酸水平密切相关,与动脉粥样硬化性脑梗死显著相关.     

Polygenic association with total homocysteine in the post-folic acid fortification era: The CARDIA study

Elevated plasma concentration of total homocysteine (tHcy) has been linked with many diseases. tHcy is associated with a variety of factors, including polymorphisms in genes involved in homocysteine metabolism. It is not clear whether US-mandated fortification of grain products with folic acid has affected the association of genetic variants with tHcy levels. We determined tHcy concentrations in sera from 997 Caucasians and 692 African Americans participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study before and after folic acid fortification. DNA was genotyped for variants present in four genes involved in homocysteine metabolism: cystathionine β-synthase (CBS) 844ins68, methionine synthase (MS) 2756A>G; methionine synthase reductase (MTRR) 66A>G and methylenetetrahydrofolate reductase (MTHFR) 677C>T and 1298A>C. A greater number of African Americans were homozygous for the MS 2756GG, MTRR 66GG and CBS 844ins68 genotypes compared to Caucasians, while prevalence of MTHFR 677TT and 1298CC genotypes was substantially lower in African Americans compared to Caucasians. The overall variance in tHcy levels at y 0, 7 and 15 that can be explained by the combined presence of all five variants increased slightly over time in Caucasians (17%, y 0; 21%, y 7; and 26%, y 15) and in African Americans (13%, y 0; 17% y 7; and 18% y 15) largely due to decrease in tHcy variance.     

Polymorphisms of the methylenetetrahydrofolate reductase gene and clinical outcomes in HLA-matched sibling allogeneic hematopoietic stem cell transplantation

To evaluate whether the C677T and A1298C polymorphisms of 5,10-methylenetetrahydrofolate reductase (MTHFR) are related to the toxicity of methotrexate (MTX) used in allogeneic stem cell transplantation, we performed association analysis between these genetic polymorphisms and the clinical outcomes of patients treated using human leukocyte antigen-matched sibling stem cell transplantation. Patients (n=72) with hematological malignancy or aplastic anemia were given a short course of MTX as a graft-versus-host disease prophylaxis. Patients with the 677TT genotype showed higher total bilirubin levels (677TT vs 677CT vs 677CC, 14.5 vs 8.6 vs 3.8 mg/dl, respectively; p=0.07) and higher aspartic transaminase levels (677TT vs 677CT vs 677CC, 678.9 vs 156.6 vs 111.8 IU/l; p=0.04). Platelet recovery to 20,000/μl was slower for patients with the 677TT genotype than for patients with other genotypes (677TT, 59 days; 677CT, 26 days; 677CC, 26 days; p=0.0075). The influences of the C677T polymorphism on treatment-related mortality (TRM) were also analyzed. One-year cumulative TRMs for patients with the TT genotype and the other genotypes were 66 and 30% (p=0.04) and their respective 1-year overall survivals were 30 and 56% (p=0.11). No association was observed between the A1298C polymorphism and clinical outcome for any of the different genotypes. Therefore, patients at high risk of developing hepatic toxicity and with a poor likelihood of survival could be selected by genotyping MTHFR C677T before allogeneic stem cell transplantation.     

Prevalence of genetic thrombophilic polymorphisms in the Sri Lankan population — implications for association study design and clinical genetic testing services

We investigated the prevalence of genotypes/alleles of single nucleotide polymorphisms (SNP) and haplotypes defined by them in three genes in which variations are associated with venous thromboembolism in 80 Sinhalese, 80 Sri Lankan Tamils and 80 Moors in the Sri Lankan population and compared the SNP data with that of other populations in Southern India and haplotype data with that of HapMap populations. The genes and polymorphisms investigated were Methylenetetrahydrofolate reductase (MTHFR) — 677C>T (rs1801133), 1298A>C (rs1801131), 1317T>C, 1793G>A (rs2274976); Factor V (F5) — 1691G>A (rs6025) and 4070A>G (rs1800595); and prothrombin (F2) — 20210G>A (rs1799963). The polymorphisms were genotyped using PCR/RFLP methods. The prevalence of the variant alleles of each polymorphism in the Sinhalese, Tamils, and Moors was MTHFR 677T: Sinhalese — 13%, Tamils — 9%, Moors — 9%. 1317T>C: Sinhalese — 0%; Tamils — 0%; Moors — 0%. 1793A: Sinhalese — 19%, Tamils — 19%, Moors — 19%. F5 1691A: Sinhalese — 2%, Tamils — 3%, Moors — 2%. 4070G: Sinhalese — 6%, Tamils — 5%, Moors — 8%. F2 20210A: Sinhalese — 0%, Tamils — 0%, Moors — 0%. The frequencies observed were similar to data from other South Indian populations; the haplotype data showed haplotypes unique to the Sri Lankan population when compared to HapMap populations. rs9651118 was identified as a SNP that splits the haplotypes harbouring the functionally significant 677T allele in the MTHFR gene. This data would be useful in planning genetic association studies in the Sri Lankan population and in deciding on which genetic variants should be tested in a clinical genetic testing service.     

Review and pooled analysis of studies on MTHFR C677T polymorphism and esophageal cancer

Esophageal cancer has been associated with tobacco and alcohol consumption, gastric reflux, exposure to nitrosamines from food or other environmental sources, and diets lacking folate. Susceptibility to esophageal cancer may be modified by functional polymorphisms in genes along the folate metabolic pathway, such as methylenetetrahydrofolate reductase (MTHFR). The C677T polymorphism is the most common functional variant, leading to a reduction in enzyme activity. We report a pooled analysis of 5 studies on the association of MTHFR C677T polymorphism and esophageal cancer, including 725 cases and 1531 controls. A significant association between the MTHFR 677 TT genotype and esophageal cancer was observed (OR=2.63, 95% CI: 1.75-3.94), although there was significant heterogeneity between studies. A sensitivity analysis excluded one study; the association between TT genotype and esophageal cancer was still present, although of reduced magnitude (OR=1.57, 95% CI: 0.96-2.56). A significant interaction between smoking and TT genotype on esophageal cancer risk was observed, while no interaction was observed between alcohol consumption and genotype.     

血浆同型半胱氨酸水平及N5,N10-亚甲四氢叶酸还原酶基因多态性与老年期抑郁症的关联研究

目的探讨血浆同型半胱氨酸(Hcy)水平及N5,N10-亚甲四氢叶酸还原酶(MTHFR)基因多态性与老年期抑郁症发病的关系.方法采用毛细管电泳-紫外检测法、聚合酶链反应-限制性片段长度多态性技术测定60例老年期抑郁症患者(抑郁症组)和80名正常人(对照组)的血浆总Hcy水平和MTHFR基因多态性.患者入组时评定汉密尔顿抑郁量表(HAMD),治疗第6周末评定疗效(HAMD减分率≥50%为有效,<50%为无效).结果 (1)抑郁症组的血浆Hcy水平[(17±6)μmol/L]明显高于对照组[(12±4)μmol/L],差异有统计学意义(P<0.01).<60岁首次发病(以下简称首发)患者(n=30)的血浆Hcy水平[(16±5)μmol/L]与≥60岁首发患者[n=30,(19±6)μmol/L]的差异无统计学意义(P>0.05);单次发作患者(n=17)的血浆Hcy水平[(18±6)μmol/L]与反复发作患者[n=43,(17±5)μmol/L]的差异无统计学意义(P>0.05);伴心脑血管疾病患者(n=27)的血浆Hcy水平[(19±6)μmol/L]与不伴心脑血管疾病患者[n=33,(16±5)μmol/L]的差异无统计学意义(P>0.05);治疗有效患者(n=40)的血浆Hcy水平[(18±5)μmol/L]与治疗无效患者 [n=20,(17±6)μmol/L]的差异无统计学意义(P>0.05).(2)抑郁症组治疗前后HAMD评分的减分率与血浆Hcy水平无显著相关性(P>0.05).(3)MTHFR C677T基因型有3种,即纯合子突变型(T/T)、杂合子突变型(T/C)和野生型(C/C).抑郁症组的基因型及等位基因频率与对照组比较,差异均无统计学意义(P>0.05).抑郁症组患者的首发年龄、发病次数、是否伴发心脑血管疾病及抗抑郁药治疗第6周末的疗效与MTHFR C677T基因型分布均无关联(P>0.05).(4)不同基因型的受试者(不论是抑郁症组还是对照组)血浆Hcy水平的差异无统计学意义(P>0.05).结论血浆Hcy水平升高可能是老年期抑郁症发病的一个独立危险因素.     

两种快速方法联合检测结核分枝杆菌耐药性

目的建立联合检测结核分枝杆菌耐药性试验方法,以提高耐药检测方法的灵敏度和特异度。方法对126株已知耐药浓度的结核分枝杆菌耐药株和敏感株分别采用硝酸盐还原试验(Nitrate Reductase Assay,NRA)和反向斑点杂交试验(reverse-dot blot hybridization,RBH),检测其对异烟肼(INH)、利福平(RFP)、链霉素(SM)和乙胺丁醇(EMB)的耐药性,并将结果与绝对浓度法结果相比较。结果硝酸盐还原试验和反向斑点杂交试验联合检测与绝对浓度法比较具有高度的一致性(P﹥0.05),异烟肼灵敏度95.5%,特异度100%;利福平灵敏度100%,特异度98.1%;链霉素灵敏度93.2%,特异度92.7%;乙胺丁醇灵敏度94.1%,特异度94.6%。结论硝酸盐还原试验和反向斑点杂交试验联合检测可作为快速结核分枝杆菌耐药性试验方法。     

同型半胱氨酸代谢相关酶基因多态性与心肌梗死关系的研究

目的研究同型半胱氨酸代谢相关酶亚甲基四氢叶酸还原酶(MTHFR)、胱硫醚-β-合成酶(CBS)及蛋氨酸合成酶(MS)基因多态性与心肌梗死(MI)相关性。方法应用聚合酶链反应-限制性内切酶片段长度多态性(PCR-RFLP)和聚合酶链反应(PCR)产物直接电泳技术,检测121例MI患者(患者组)和500例健康人(正常对照组)的MTHFR C677T、CBS 844 ins68和MS A2756G基因多态性。结果MTHFR C677T基因型分别为:CC野生型、CT杂合型、TT突变型。其在患者组分布频率分别为14.0%、46.3%、39.7%,T等位基因频率为62.85%,C等位基因频率为37.15%;正常对照组中为35.6%、44.0%2、0.4%,T等位基因频率为42.4%,C等位基因频率为57.6%。两组间各基因频率及等位基因频率比较差异均具有统计学意义(P<0.05)。而CBS 844ins 68和MSA2756G的基因型频率分布,两组间差异均无统计学意义(P>0.05)。结论MTHFR基因TT基因型,T等位基因与MI具有相关性;而CBS 844 ins68及MS A2756G基因多态性可能与MI发生无直接相关性。     

MTHFR基因多态性与儿童支气管哮喘易感性及糖皮质激素疗效的相关性

目的 探讨亚甲基四氢叶酸还原酶（methylenetetrahydrofolate reductase,MTHFR）基因多态性与儿童支气管哮喘易感性及糖皮质激素（glucocorticoid,GC）疗效的相关性。 方法 选取2018年6月至2020年12月住院治疗的儿童支气管哮喘患儿173例为观察组,均接受GC雾化吸入治疗,连续3个月。选取同期体检的健康儿童178例为对照组。采用PCR检测两组受试儿MTHFR基因C677T位点的基因型,分析两组基因型分布差异性;比较观察组不同基因型患儿治疗前后血清免疫球蛋白E、白细胞介素-8（interleukin-8,IL-8）、白三烯B4（leukotriene B4,LTB4）水平,肺功能指标差异及临床疗效差异。 结果 与对照组相比,观察组TT基因型及T等位基因频率均显著升高（P<0.001）;TT/CT基因型及T等位基因是支气管哮喘易感性的独立危险因素（OR分别为6.615、7.055,P<0.001）。GC治疗后3种基因型患儿免疫球蛋白E、IL-8和LTB4水平较治疗前显著降低,第1秒用力呼气容积（forced expiratory volume in 1 second,FEV1）、用力肺活量（forced vital capacity,FVC）、FEV1/FVC%较治疗前显著升高（P<0.001）;TT基因型患儿IL-8和LTB4水平显著低于CC基因型患儿,LTB4水平明显低于CT基因型患儿,TT基因型患儿FVC明显高于CT基因型患儿,FEV1/FVC%显著高于CC基因型患儿（P<0.05）;治疗后3种基因型患儿临床GC治疗疗效比较差异有统计学意义,其中TT基因型患儿GC疗效良好比例显著高于CC基因型患儿（P<0.05）,且TT基因型是GC疗效良好的独立影响因素（OR=2.111,P=0.018）。 结论 MTHFR基因多态性与儿童哮喘易感性及GC疗效相关,携带TT/CT基因型儿童支气管哮喘发病风险更高,TT基因型对GC治疗具有更高的敏感性。     

阿托伐他汀对大鼠脑出血后血肿周围组织细胞凋亡和细胞色素c表达的影响

目的 探讨阿托伐他汀对大鼠脑出血后血肿周围组织细胞凋亡和细胞色素c(Cytochrome c,CytC)表达的影响.方法 108只雄性Sprague-Dawley大鼠随机分为假手术组、生理盐水对照组和阿托伐他汀组(每组36只),各组再分为6h、12 h、ld、3d、5d和7d时间点(每个时间点6只).采用改良二次注血法制作脑出血模型.阿托伐他汀组在模型制作后给予阿托伐他汀灌胃(20 mg/kg,1次/d),生理盐水对照组给予等体积生理盐水.采用行为学评价进行神经功能评分,TUNEL染色法检测血肿周围细胞凋亡,免疫组织化学法检测血肿周围组织CytC表达.结果 行为学评价显示,阿托伐他汀组和生理盐水对照组神经功能评分均随着时间的推移而逐渐下降,6h、12 h、1d和3d时无显著性差异,但5 d[(0.50±0.55)分对(1.50±0.55)分;t=3.162,P=0.010]和7d[(0.17±0.41)分对(1.00±0.63)分;t=2.712,P =0.022]时阿托伐他汀组神经功能评分显著性低于生理盐水对照组.TUNEL染色法显示,生理盐水对照组与阿托伐他汀组凋亡细胞数量均先增加后减少,高峰出现在模型制作后1d时.各组间相同时间点血肿周围凋亡细胞数量均存在显著性差异(P均=0.000),且生理盐水对照组显著性多于假手术组和阿托伐他汀组(P均＜0.05),但在7d时阿托伐他汀组凋亡细胞数量与假手术组无显著性差异[(12.69±3.35)个对(9.33 ±2.07)个;P=0.148].免疫组织化学法显示,生理盐水对照组与阿托伐他汀组CytC阳性细胞数量均先增加后减少,生理盐水对照组高峰出现在模型制作后12h时[(68.19±11.93)个],而阿托伐他汀组出现在模型制作后ld时[(35.64±9.12)个].各组间相同时间点血肿周围CytC阳性细胞数量均存在显著性差异(P均=0.000),且生理盐水对照组显著性多于假手术组和阿托伐他汀组(P均＜0.05),但在7d时阿托伐他汀组CytC阳性细胞数量与假手术组无显著性差异[(16.08±3.80)个对(13.67±2.94)个;P=0.349].结论 阿托伐他汀可抑制脑出血后血肿周围神经细胞CytC释放,从而抑制CytC介导的细胞凋亡,减轻脑出血后脑神经功能缺损.