LOD

LoD
  • 文章类型: English Abstract
    在日本官方检测未经授权的转基因(GM)木瓜的方法中,具有DNA聚合酶的两种类型的实时PCR试剂之一(TaqMan基因主混合物[TaqMan基因]或FastGeneQPCR探针Mastermixw/ROX[FastGene])主要用于测量。2022年,我们对未经授权的转基因木瓜品系PRSV-YK进行了实验室性能研究,结果表明,使用TaqMan基因与7500Fast和7500Real-TimePCR系统(ABI7500)和QuantStudio12KFlex(QS12K)获得了PRSV-YK检测测试的高阈值循环(Cq)值,表明假阴性的可能性。需要评估所有未经授权的GM木瓜线检测测试出现类似问题的可能性。在这项研究中,我们对未经授权的转基因木瓜品系(PRSV-YK,PRSV-SC,和PRSV-HN),花椰菜花叶病毒35S启动子(CaM),和木瓜阳性对照(Chy),并检查了每种测试的检测限(LOD)如何受到两种类型的DNA聚合酶(TaqMan基因和FastGene)和三种类型的实时PCR仪器(ABI7500,QS12K,和LightCycler480仪器II[LC480])。在使用ABI7500和QS12K的PRSV-YK和PRSV-SC检测试验中,用TaqMan基因测量显示比FastGene更高的LOD。在这种情况下,在扩增图上证实了指数扩增曲线;然而,扩增曲线没有越过ΔRn阈值线,并且在阈值线=0.2的情况下没有获得正确的Cq值。其他测试(PRSV-HN,CaM,和Chy与ABI7500和QS12K,使用LC480)进行的所有检测测试均显示,使用两种DNA聚合酶进行的每次测试的LOD均无重要差异。因此,用ABI7500或QS12K进行PRSV-YK和PRSV-SC检测测试时,FastGene应用于避免在低混合水平下含有GM木瓜系PRSV-YK和PRSV-SC的食物的假阴性。
    In the Japanese official detection method for unauthorized genetically modified (GM) papayas, one of two types of real-time PCR reagents with DNA polymerase (TaqMan Gene Master Mix [TaqMan Gene] or FastGene QPCR Probe Mastermix w/ROX [FastGene]) is primarily used for measurement. In 2022, we conducted a laboratory performance study on the unauthorized GM papaya line PRSV-YK, and the results revealed that high threshold cycle (Cq) values for the PRSV-YK detection test were obtained using TaqMan Gene with the 7500 Fast & 7500 Real-Time PCR System (ABI7500) and QuantStudio 12K Flex (QS12K), indicating the possibility of false negatives. The possibility of similar problems with all unauthorized GM papaya lines detection tests needs to be evaluated. In this study, we performed detection tests on unauthorized GM papaya lines (PRSV-YK, PRSV-SC, and PRSV-HN), the cauliflower mosaic virus 35S promotor (CaM), and a papaya positive control (Chy), and examined how the limits of detection (LOD) for each test are affected by two types of DNA polymerases (TaqMan Gene and FastGene) and three types of real-time PCR instruments (ABI7500, QS12K, and LightCycler 480 Instrument II [LC480]). In the PRSV-YK and PRSV-SC detection tests using ABI7500 and QS12K, measurement with TaqMan Gene showed a higher LOD than FastGene. In this case, an exponential amplification curve was confirmed on the amplification plot; however, the amplification curve did not cross the ΔRn threshold line and the correct Cq value was not obtained with a threshold line=0.2. The other tests (PRSV-HN, CaM, and Chy with ABI7500 and QS12K, and all detection tests with LC480) showed no important differences in the LOD for each test using either DNA polymerase. Therefore, when performing PRSV-YK and PRSV-SC detection tests with the ABI7500 or QS12K, FastGene should be used to avoid false negatives for foods containing GM papaya lines PRSV-YK and PRSV-SC at low mixing levels.
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  • 文章类型: Journal Article
    氟化物检测在化学领域发挥着重要作用,生物,和医药领域,特别是保持身体健康和抵抗环境污染。在这里,成功开发了一种具有良好灵敏度的尿石素B荧光探针,选择性,抗干扰能力强。检测下限(LOD)为0.156μM,并且对F-的即时响应时间小于1s。该探针适用于在425(蓝色)和566nm(橙色)具有两个不同发射带的溶液中的F-的定量和定性比率检测,CIE的坐标从(0.38,0.41)变为(0.22,0.11)。尿石素B对F-表现出显著的比率荧光响应。通过NMR和电子光谱实验结合随时间变化的密度泛函理论计算,进一步提出了检测机理。
    Fluoride detection has been playing an important role in chemical, biological, and medicinal field, especially for keeping physical health and resisting environmental pollution. Herein, a urolithin B fluorescent probe has been successfully developed with good sensitivity, selectivity, anti-interference ability. The low limit of detection (LOD) refers to 0.156 μM, and the instant response time to F- is less than 1 s. The probe is suitable for quantitatively and qualitatively ratiometric detection for F- in solution with two distinct emission bands at 425 (blue) and 566 nm (orange), with the coordinate change of CIE from (0.38, 0.41) to (0.22, 0.11). Urolithin B displayed a remarkable ratiometric fluorescence response towards F-. The detection mechanistic was further proposed by NMR and electronic spectroscopic experiments combining with time-dependent density functional theoretical calculation.
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  • 文章类型: Journal Article
    癌症诊断最近一直处于医学研究的前沿,正在努力开发用于检测患者癌症的设备和技术。用于癌症诊断的一种有前景的方法是检测血液样品中的循环肿瘤细胞(CTC)。从不同背景的血细胞中分离出这些稀有细胞并对其进行分析可以为疾病的阶段和致死性提供有价值的见解。在这里,我们介绍了在聚合物圆盘上利用离心力进行细胞分离的离心微流体平台的设计和制造。分离单元利用主动和被动两种方法。换句话说,除了为通道引入新颖的几何形状外,外部磁场也用于将靶细胞与背景细胞分离。为了使外部字段发挥作用,必须首先用抗体缀合的纳米颗粒标记CTC;然后应进行分离过程。在实验测试之前,进行了数值研究以确定最佳参数;角速度和磁化强度研究表明,2000rpm和868,000(kA/m)是所设计设备达到白细胞(WBC)和CTC效率100%的最佳条件。这些结果表明,通道的被动区域主要有助于靶细胞的聚焦,并表明,与之字形几何相比,在膨胀-收缩几何中的聚焦效应更为明显。此外,结果证明,在分离效率方面,弯曲通道的几何形状比直线通道的几何形状表现更好。然而,如果分离仅依赖于通道几何形状,大多数细胞将被引导到非目标腔室,导致次优结果。这是由于作用在细胞上的力的方向。然而,包括外部磁场改善了净力的方向并提高了分离效率。最后,对研究的数值和实验结果进行了比较,引入弯曲的膨胀-收缩通道作为具有100%和92%CTC分离效率的最佳几何形状,分别。
    Cancer diagnosis has recently been at the forefront of recent medical research, with ongoing efforts to develop devices and technologies for detecting cancer in patients. One promising approach for cancer diagnosis is the detection of Circulating Tumor Cells (CTCs) in blood samples. Separating these rare cells from the diverse background of blood cells and analyzing them can provide valuable insights into the disease\'s stage and lethality. Here we present the design and fabrication of a centrifugal microfluidic platform on a polymeric disk that utilizes centrifugal forces for cell isolation. The separation units exploit both active and passive methods. In other words, in addition to introducing novel geometry for channels, an external magnetic field is also employed to separate the target cells from the background cells. In order for the external field to function, the CTCs must first be labeled with antibody-conjugated nanoparticles; the separation process should be then performed. Before the experimental tests, a numerical study was done to determine the optimum parameters; the angular velocity and magnetization investigations showed that 2000 rpm and 868,000 (kA/m) are the optimum conditions for the designed device to reach the efficiency of 100% for both White Blood Cells (WBCs) and CTCs. These results indicate that the passive region of the channels primarily contributes to the focusing of the target cells, and showed that the focusing effect is more pronounced in the expansion-contraction geometry compared to the zigzag geometry. Additionally, the results proved that curved channel geometries performed better than straight ones in terms of separation efficiency. However, if the separation relies solely on channel geometry, the majority of cells would be directed towards the non-target chamber, leading to suboptimal results. This is due to the direction of the forces acting on the cells. However, including an external magnetic field improves the direction of the net force and enhances the separation efficiency. Finally, the numerical and experimental results of the study were compared, and the curved expansion-contraction channel is introduced as the best geometry having 100% and ∼92% CTC separation efficiency, respectively.
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  • 文章类型: Journal Article
    在这项研究中,我们评估了内部开发的针对SARS-CoV-2RNA的rRT-PCR检测方法的性能,该方法靶向包膜(E)和核衣壳(N)基因,内部对照为人RNA酶P。通过参考试剂盒在第1位点测试了50例SARS-CoV-2阳性样品和50例阴性样品,并在第2位点盲目测试了这些样品中的一个子集(30例阳性和16例阴性)。通过使用复制缺陷的完整SARS-CoV-2基因组和已知拷贝数来计算检测限(LoD),其中使用伪病毒样品来评估准确性。在站点1上,在50个SARS-CoV-2阳性样本中,有24、18和8个样本显示为高(Ct&lt;26),中等(26<Ct≤32),病毒载量低(32<Ct≤38),分别,而在站点2中,在30个SARS-CoV-2阳性样本中,高,中度,在10个样本中的每个样本中都发现了低病毒载量。然而,在阴性样品中未检测到SARS-CoV-2。所以,两个位点的内部检测均显示100%的灵敏度和特异性,在RTPCR机器之间没有观察到差异.内部试剂盒的Ct值与参考试剂盒具有非常好的相关性。LoD被确定为100拷贝/mL。它还在突变型和野生型SARS-CoV-2病毒中显示出100%的准确性。与商业进口的CE-IVD标记的FDA授权试剂盒相比,该Bangasure™RT-PCR试剂盒在检测SARS-CoV-2病毒RNA方面表现出优异的性能。
    In this study, we evaluated the performance of the in-house developed rRT-PCR assay for SARS-CoV-2 RNA targeting the envelope (E) and nucleocapsid (N) genes with internal control as human RNase P. A total of 50 positive samples and 50 negative samples of SARS-CoV-2 were tested by a reference kit at site 1 and a subset (30 positives and 16 negatives) of these samples are tested blindly at site 2. The limit of detection (LoD) was calculated by using a replication-deficient complete SARS-CoV-2 genome and known copy numbers, where Pseudo-virus samples were used to evaluate accuracy. On site 1, among the 50 SARS-CoV-2 positive samples 24, 18, and eight samples showed high (Ct < 26), moderate (26 < Ct ≤ 32), and low (32 < Ct ≤ 38) viral load, respectively, whereas in site 2, out of 30 SARS-CoV-2 positive samples, high, moderate, and low viral loads were found in each of the 10 samples. However, SARS-CoV-2 was not detected in the negative sample. So, in-house assays at both sites showed 100% sensitivity and specificity with no difference observed between RT PCR machines. The Ct values of the in-house kit had a very good correlation with the reference kits. LoD was determined as 100 copies/mL. It also displayed 100% accuracy in mutant and wild-type SARS-CoV-2 virus. This Bangasure™ RT-PCR kit shows excellent performance in detecting SARS-CoV-2 viral RNA compared to commercially imported CE-IVD marked FDA authorized kits.
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  • 文章类型: Journal Article
    在这篇评论文章中,我们从2007年到2021年对头发中NPS的提取和色谱分析方法进行了概述,评估了检测限(LOD),定量限(LOQ),报告限制(LOR),和每个NPS报告的识别极限(LOI)值。我们的评论旨在强调现代头发分析技术的局限性,以及正确评估和使用与NPS头发分析目标相关的分析结果的先决条件。在选定的研究中,报告了总共280NPS的检测。检测到的NPS属于七个类别:具有109种不同物质的合成大麻素,合成阿片类药物58,卡西诺酮50,苯乙胺34,其他NPS15,色胺10,和哌嗪与四种物质。对真实法医/临床病例的NPS头发分析报告仅检测到80个NPS(在280个目标病例中),明显高于各自的LOD。本文对NPS头发分析的分析方案显示,识别尽可能多的NPS的趋势不断增长;提取方法似乎有有限的改进潜力,而各种质谱技术和相关仪器为开发和应用提供了广阔的领域。头发是过去慢性的生物指标,亚慢性,and,甚至,在某些情况下,急性暴露于外源性物质。因此,该领域的未来研究可以促进NPS头发分析,并旨在监测NPS的扩展和社区使用程度。
    In this review article, we performed an overview of extraction and chromatographic analysis methods of NPS in hair from 2007 to 2021, evaluating the limit of detection (LOD), limit of quantification (LOQ), limit of reporting (LOR), and limit of identification (LOI) values reported for each NPS. Our review aimed to highlight the limitations of modern hair analytical techniques, and the prerequisites for the proper evaluation and use of analytical results in relation to the objectives of NPS hair analysis. In the selected studies the detection of a total of 280 NPS was reported. The detected NPS belonged to seven classes: synthetic cannabinoids with 109 different substances, synthetic opioids with 58, cathinones with 50, phenethylamines with 34, other NPS with 15, tryptamines with ten, and piperazines with four substances. The NPS hair analysis of real forensic/ clinical cases reported the detection of only 80 NPS (out of the 280 targeted), in significantly higher levels than the respective LODs. The analytical protocols reviewed herein for NPS hair analysis showed continuously growing trends to identify as many NPS as possible; the extraction methods seem to have a limited potential to improve, while the various mass spectroscopic techniques and relevant instrumentation provide an enormous field for development and application. Hair is a biological indicator of the past chronic, sub-chronic, and, even, in certain cases, acute exposure to xenobiotics. Therefore, future research in the field could progress NPS hair analysis and aim the monitoring of NPS expansion and extent of use in the community.
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  • 文章类型: Clinical Trial, Phase II
    OBJECTIVE: Patients with chronic hepatitis C virus (HCV) infection and prior null response (<2 log HCV RNA decline after ⩾ 12 weeks of PegIFN/RBV) have limited options. We evaluated daclatasvir plus once- or twice-daily asunaprevir in non-cirrhotic genotype 1 null responders.
    METHODS: In this randomized, phase 2a, open-label, 24-week treatment study, 101 patients received daclatasvir (60 mg) once-daily. In addition, 38 genotype 1b patients received asunaprevir (200mg) twice- (DUAL A1) or once-daily (DUAL A2); 36 genotype 1a and 5 genotype 1b patients received asunaprevir twice- (QUAD B1) or once-daily (QUAD B2) plus PegIFN/RBV; and 18 genotype 1a and 4 genotype 1b patients received asunaprevir twice-daily plus ribavirin (TRIPLE B3). The primary endpoint was undetectable HCV RNA 12 weeks post-treatment (sustained virologic response, SVR12).
    RESULTS: Across all groups, mean HCV RNA was ⩾ 6 log IU/ml, and 99% of patients had a non-CC IL28B genotype. SVR12 rates were 78% (A1), 65% (A2), 95% (B1), and 95% (B2). In B3, most genotype 1a patients experienced virologic breakthrough. The most common adverse events were headache, diarrhea, and asthenia. Grade 3-4 aminotransferase elevations were infrequent and not treatment-limiting.
    CONCLUSIONS: In genotype 1 null responders, daclatasvir plus twice-daily asunaprevir DUAL therapy is effective for most genotype 1b patients, and daclatasvir, asunaprevir, and PegIFN/RBV QUAD therapy is effective for nearly all genotype 1a and 1b patients; but neither DUAL nor TRIPLE therapy is effective for genotype 1a patients. Interferon-free regimens including daclatasvir and twice-daily asunaprevir for genotype 1 null responders should be tailored to subtype.
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  • 文章类型: Journal Article
    背景:脑静脉血栓形成(CVT)是一种罕见的疾病,与其他部位的血栓形成相比有一些差异,包括年轻人的频率更高,女性和口服避孕药使用者。凝血酶激活的纤维蛋白溶解抑制剂(TAFI)是纤维蛋白溶解的调节剂,其水平受基因控制,其增加与血栓形成有关。我们的目的是在一项病例对照研究中,与其他部位静脉血栓形成和对照相比,CVT和TAFI单核苷酸多态性(SNP)及其单倍型之间的关联。
    方法:将72例CVT患者与143例无血栓栓塞事件史的患者(对照组)和128例四肢深静脉血栓形成和/或肺栓塞患者(静脉血栓栓塞-VTE组)进行比较。通过限制性片段长度多态性或等位基因特异性PCR对F220210G>A的SNP进行基因分型,F51691G>A,TAFI(-1053C>T,-438G>A,505G>A,1040C>T和+1542C>G)。
    结果:TAFI505G>A/1040C>T/+1542C>GSNP的GTC单倍型与与对照组[比值比(OR)2.67,95%置信区间(CI):1.13-6.34)和VTE组(OR2.51,95CI:1.07-8.06)相比,CVT风险增加。在评估无源性或激素相关血栓形成病例时,CVT风险变得更加明显:CVT与对照组(OR3.24,95CI:1.19-8.82)和VTE组(OR4.32,95CI:1.27-14.63)相比。
    结论:我们的数据表明,与对照组和VTE病例相比,TAFI505G>A/1040C>T/+1542C>GSNP的GTC单倍型增加了CVT的风险。需要进一步的研究来证实我们的发现。
    BACKGROUND: Cerebral venous thrombosis (CVT) is an uncommon disease with some differences compared to other-site thrombosis, including a higher frequency in young people, female sex and oral contraceptive users. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a regulator of fibrinolysis, whose levels are genetically controlled and its increase is associated to thrombosis. Our objective was to investigate in a case-control study the association between CVT and TAFI single nucleotide polymorphisms (SNPs) and its haplotypes in comparison to other-site venous thrombosis and controls.
    METHODS: Seventy two patients with CVT were compared to 143 individuals with no history of thromboembolic events (control group) and to 128 patients with deep vein thrombosis in the limbs and/or pulmonary embolism (venous thromboembolism-VTE group). SNPs were genotyped by restriction fragment length polymorphism or allele-specific PCR for F2 20210G>A, F5 1691G>A, TAFI (-1053C>T, -438G>A, 505G>A, 1040C>T and +1542C>G).
    RESULTS: The GTC haplotype for TAFI 505G>A/1040C>T/+1542C>G SNPs was associated with an increased risk of CVT compared to controls [odds ratio (OR) 2.67, 95% confidence interval (CI): 1.13 - 6.34) and VTE group (OR 2.51, 95%CI: 1.07 - 8.06). The CVT risk became even more pronounced when evaluating unprovoked or hormone-related thrombosis cases: CVT compared to controls (OR 3.24, 95%CI: 1.19 - 8.82) and VTE group (OR 4.32, 95%CI: 1.27 - 14.63).
    CONCLUSIONS: Our data indicate that the GTC haplotype for TAFI 505G>A/1040C>T/+1542C>G SNPs increased the risk of CVT in comparison to controls and VTE cases. Further studies are required to confirm our findings.
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  • 文章类型: Journal Article
    Indoor pesticide exposure is a growing concern, particularly for pyrethroids, a commonly used class of pesticides. Pyrethroid concentrations may be especially high in homes of immigrant farm worker families, who often live in close proximity to agricultural fields and are faced with poor housing conditions, potentially causing high pest infestation and pesticide use. We investigate levels of pyrethroids in the house dust of farm worker family homes in a study of mothers and children living in Mendota, CA, within the population-based Mexican Immigration to California: Agricultural Safety and Acculturation (MICASA) Study. We present pesticide use data and levels of pyrethroid pesticides in indoor dust collected in 2009 as measured by questionnaires and a GC/MS analysis of the pyrethroids cis- and trans-permethrin, cypermethrin, deltamethrin, esfenvalerate and resmethrin in single dust samples collected from 55 households. Cis- and trans-permethrin had the highest detection frequencies at 67%, with median concentrations of 244 and 172ng/g dust, respectively. Cypermethrin was detected in 52% of the homes and had a median concentration of 186ng/g dust. Esfenvalerate, resmethrin and deltamethrin were detected in less than half the samples. We compared the pyrethroid concentrations found in our study to other studies looking at both rural and urban homes and daycares. Lower detection frequencies and/or lower median concentrations of cis- and trans-permethrin and cypermethrin were observed in our study as compared to those studies. However, deltamethrin, esfenvalerate and resmethrin were detected more frequently in the house dust from our study than in the other studies. Because households whose children had higher urinary pyrethroid metabolite levels were more likely to be analyzed in this study, a positive bias in our estimates of household pyrethroid levels may be expected. A positive association was observed with reported outdoor pesticide use and cypermethrin levels found in the indoor dust samples (rs=0.28, p=0.0450). There was also a positive association seen with summed pyrethroid levels in house dust and the results of a pesticide inventory conducted by field staff (rs=0.32, p=0.018), a potentially useful predictor of pesticide exposure in farm worker family homes. Further research is warranted to fully investigate the utility of such a measure.
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  • 文章类型: Evaluation Study
    Amino acids, as the main contributors to taste, are usually found in relatively high levels in bitter foods. In this work, we focused on seeking a rapid, sensitive and simple method to determine FAA for large batches of micro-samples and to explore the relationship between FAA and bitterness. Overall condition optimisation indicated that the new UDME technique offered higher derivatisation yields and extraction efficiencies than traditional methods. Only 35min was needed in the whole operation process. Very low LLOQ (Lower limit of quantification: 0.21-5.43nmol/L) for FAA in twelve bitter foods was obtained, with which BTT (bitter taste thresholds) and CABT (content of FAA at BTT level) were newly determined. The ratio of CABT to BTT increased with decreasing of BTT. This work provided powerful potential for the high-throughput trace analysis of micro-sample and also a methodology to study the relationship between the chemical constituents and the taste.
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  • 文章类型: Journal Article
    The immunotoxicity of the synthetic pyrethroid α-cypermethrin (αCYP) was assessed in 30 occupationally exposed greenhouse workers and 30 non-exposed controls by comparing plasma levels of IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, TNF-α, TNF-β and INF-γ. Urinary 3-phenoxybenzoic acid was used as an exposure biomarker. Exposed workers showed neither clinical signs of immunosuppression nor alterations in total leukocytes or leukocyte subpopulations, whereas significant differences (p<0.05) were found for IL-12p70 and highly significant differences (p<0.001) for INF-γ, IL-2 and IL-8, which are involved in antitumor immunity and response to infection. Proinflammatory cytokines IL-2, IL-8, IL-12p70 and IFN-γ play a significant role against infection and cancer. We report the first data on the ability of αCYP to reduce proinflammatory cytokine levels in an exposed healthy human population. Findings support the hypothesis that pyrethroid exposure may reduce host defenses against infection and cancer, particularly in subjects with impaired immune capacity.
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