LC–MS/MS progress in newborn screening

Newborn screening programs detect treatable disorders in infants before they become symptomatic. Liquid chromatography-tandem mass spectrometry (LC–MS/MS) has greatly increased the screening possibilities by monitoring levels of amino acids and acylcarnitines. After the initial screening step, LC–MS/MS can also be used in screening positive samples as a second tier test to differentiate between true and false positive samples.As the list of disorders screened for by LC-tandem MS increases, questions arise about screening for untreatable disorders, such as some lysosomal storage diseases (LSDs). For LSDs screening methods are being developed and tested more quickly than treatments are becoming available. This goes against one of the main tenets of newborn screening which requires that a treatment be available.LC–MS/MS can detect several disorders with a single injection, which is important in high throughput laboratories. Measuring different amino acids and acylcarnitines can be used to detect up to 45 different inherited disorders depending on how diseases are counted. The LSD assays are designed in a similar way to detect multiple disorders with common sample preparation and a single injection. The clinical implications of applying this technology to NBS on a large scale in many jurisdictions across the world are discussed.     

Continence in MS

Urinary and faecal incontinence can be problems in patients with multiple sclerosis. This article updates readers on the types of MS and its medical management and examines the products and drugs available in the treatment of incontinence.     

ID-LC/MS/MS方法测量血清未结合雌三醇的协作研究

摘要：目的用同位素稀释液相色谱串联质谱（ID-LC/MS/MS）候选参考方法进行实验室间血清未结合雌三醇（uE3）协作研究,通过该研究进一步确认方法的性能特征（正确度和精密度）,并将该方法在国内参考实验室推广,推动uE3标准化进程。方法依据ISO/WD 15725-1和GB/T 6379标准,拟定我国血清uE3协作研究方案。协作研究分为两个阶段：初步试验和正式试验,共9家参考实验室参加。按要求收集5个浓度水平样品并进行均匀性评价,分发到各实验室,每个样品重复测量5次,连续测量3天。计算各实验室测量结果的偏移和精密度。测量结果采用格拉布斯（Grubbs）检验和柯克伦（Cochran）检验,识别离群值和离群实验室。根据合格实验室的结果计算靶值,并向离群实验室和偏出允许范围的实验室提供整改建议。结果（1）样品均匀性评价,所有样品测量结果计算F值均小于F0.05（9, 20）临界值,样品中uE3是均匀的。（2）初步试验：Grubbs检验,1个实验室测量结果为离群值;Cochran检验2个实验室检验结果为离群值。剔除离群值后计算靶值,分别为2017E301:（22.08±0.24）nmol/L;2017E302：（33.46±1.67）nmol/L。2个实验室结果超出允许范围。（3）正式试验：Grubbs检验,所有实验室测量结果均未检出离群值。Cochran检验3个实验室数据出现离群值。剔除离群值后计算靶值,分别为2017E303:（10.36±0.35）nmol/L;2017E304:（15.47±0.26）nmol/L;2017E305:（46.97±1.19）nmol/L。;各实验室间测量结果不精密度分别为（1.14%～2.21%,0.79%～1.93%,0.60%～2.09%）,测量结果偏移分别为（-6.18%～4.83%,-2.26%～2.39%,-4.19%～4.07%）。结论通过组织开展协作研究,确认了各参考实验室通过协作研究方案能够快速建立并运行uE3候选参考方法,除个别实验室外各实验室的检测性能满足预定要求（不精密度<3.0%,偏移<7.5%）,进一步确认了该方法的性能和各实验室运行参考方法的能力。通过初步研究和正式研究对研究方案的各实验环节进行了验证和完善;推动了uE3项目参考方法在我国参考实验室的运行,为后续厂商试剂主校准品联合定值或标准物质研制搭建了平台,促进uE3项目的标准化。     

串联质谱和高效液相色谱-串联质谱二次筛查联合应用于新生儿MMA筛查

目的探讨串联质谱和高效液相色谱-串联质谱二次筛查联合应用在甲基丙二酸血症(MMA)中的筛查价值。方法收集新生儿串联质谱初筛结果中C3、C3/C2、C3/C0单一或多个指标异常的新生儿干血滤纸片标本,用高效液相色谱-串联质谱的方法定量检测原始血片中甲基丙二酸、甲基枸橼酸和高半胱氨酸,对二次筛查后疑似阳性的新生儿进行召回复查,并进行尿气相色谱/质谱检测。临床诊断患儿进一步予以基因检测进行确诊。结果共收集423例C3、C3/C2、C3/C0单一或多个指标异常的新生儿筛查标本,初筛阳性率约为1%,行联合筛查检测结果发现8例标本中甲基丙二酸和同型半胱氨酸表达水平明显升高,召回复查尿气相色谱质谱提示甲基丙二酸轻度升高。结论串联质谱和高效液相色谱-串联质谱联合应用可以提高新生儿MMA筛查的阳性预测值、降低假阳性率,在新生儿遗传代谢病筛查中具有重要价值。     

LC-MS/MS systematic toxicological analysis: comparison of MS/MS spectra obtained with different instruments and settings

OBJECTIVES: To compare the mass spectra obtained using a linear-ion-trap (LIT) tandem mass spectrometer (QTRAP) operated in the "enhanced product ion scan" (EPI) mode with those obtained in the classical triple-quadrupole product ion scan (PIS) mode run on the same as well as on two other instruments (TSQ-Quantum and Quattro-Micro). DESIGN AND METHODS: After tentative standardization of ion fragmentation and transmission in both polarities using a reference compound (glafenine) on the three instruments, eight test compounds detected in the positive mode and five in the negative mode were systematically infused in different ionization sources and spectral acquisition performed over approximately 5 s. The relative intensity of the ions present in the resulting spectra was quantitatively and statistically compared. Also, the intra-day and inter-day variabilities of these relative intensities, as well as the effect of increasing compound concentration, were studied using QTRAP operated in EPI mode. RESULTS: The EPI and PIS modes operated on a single LIT MS/MS instrument resulted in significant differences in relative ion intensities in both polarities, and so did the other two instruments despite prior standardization with glafenine. Some fragments could be absent in certain spectra, but no unexpected or unique fragments showed up. Intra-day variability was smaller in the LIT EPI than in the regular PIS mode and in the positive than in the negative polarity. In EPI mode, both intra- and inter-day variabilities increased when the relative intensity decreased. The effect of increasing concentration on the relative intensity of major and minor ions was small but significant in both polarities. Finally, contamination and cleansing of the ionization source also had noticeable effects on MS/MS spectra, though the cause is unclear. CONCLUSIONS: MS/MS spectra do not offer the expected inter-instrument reproducibility despite an attempt at standardizing the fragmentation conditions using a reference compound. However, although the inter-instrument differences in ion relative intensity were significant, the spectra obtained looked almost similar. This suggests that in library searching algorithms, higher weight should be assigned for the m/z ratios than for their relative intensity in the spectra.     

Intermittent self-catheterisation in MS

People with multiple sclerosis may experience complex bladder problems; intermittent self-catheterisation can be used in cases of incomplete bladder emptying. This literature review examines the qualitative research on the use of ISC in patients with MS, focusing on concordance, training and quality of life.     

Cytokines in MS lesion

A variety of cytokines are involved in the pathogenesis of multiple sclerosis(MS), either in induction phase and effector phase. In order to interact with immune cells, the cells in the brain have to express MHC antigens which they do not usually express. Cytokines such as IFN gamma, IL-3 and TNF alpha induce MHC antigen expression on neural cells. IFN gamma also induces costimulatory molecule for antigen presentation and also induce IL-12, a critical cytokine in T helper cell differentiation, in microglia. Although TNF alpha is a critical cytokines in effector phase, other cytokines and chemokines have also been shown to play roles on the development of inflammatory demyelination and gliosis. In this chapter, we will review the cytokine profile of MS lesions.     

Random walks with shape prior for cochlea segmentation in ex vivo $$\mu \hbox {CT}$$

Purpose

Cochlear implantation is a safe and effective surgical procedure to restore hearing in deaf patients. However, the level of restoration achieved may vary due to differences in anatomy, implant type and surgical access. In order to reduce the variability of the surgical outcomes, we previously proposed the use of a high-resolution model built from \(\mu \hbox {CT}\) images and then adapted to patient-specific clinical CT scans. As the accuracy of the model is dependent on the precision of the original segmentation, it is extremely important to have accurate \(\mu \hbox {CT}\) segmentation algorithms.

Methods

We propose a new framework for cochlea segmentation in ex vivo \(\mu \hbox {CT}\) images using random walks where a distance-based shape prior is combined with a region term estimated by a Gaussian mixture model. The prior is also weighted by a confidence map to adjust its influence according to the strength of the image contour. Random walks is performed iteratively, and the prior mask is aligned in every iteration.

Results

We tested the proposed approach in ten \(\mu \hbox {CT}\) data sets and compared it with other random walks-based segmentation techniques such as guided random walks (Eslami et al. in Med Image Anal 17(2):236–253, 2013) and constrained random walks (Li et al. in Advances in image and video technology. Springer, Berlin, pp 215–226, 2012). Our approach demonstrated higher accuracy results due to the probability density model constituted by the region term and shape prior information weighed by a confidence map.

Conclusion

The weighted combination of the distance-based shape prior with a region term into random walks provides accurate segmentations of the cochlea. The experiments suggest that the proposed approach is robust for cochlea segmentation.

     

国产MALDI-TOF MS系统microTyper MS对革兰阴性菌的鉴定性能评估

目的 评估国产基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)系统microTyper MS鉴定革兰阴性菌的性能.方法 使用国产MALDI-TOF MS系统microTyper MS与进口质谱系统VITEK MS系统同步鉴定该实验室储存的标准菌株及2018年6月至2019年6月临床分离的革兰阴性菌株.鉴定结果不一致时,使用表型试验或16 s rDNA测序进行确认,以此评估microTyper MS对革兰阴性菌的鉴定能力.结果 纳入鉴定的革兰阴性菌株一共45属4509株.VITEK MS系统准确鉴定4419株,准确率为98.0％;microTyper MS准确鉴定4405株,准确率为97.7％.结论 microTyper MS在革兰阴性菌鉴定方面具有与VITEK MS系统相仿的临床细菌鉴定能力.