A study to explore opinions and attitudes of Saudi Arabian MR professionals on the current status of routine MR scanner quality assurance testing in the Kingdom of Saudi Arabia

IntroductionInternationally it is recommended that quality assurance (QA) testing of MR systems is the responsibility of MR professionals to ensure efficient scanner performance. This study aims to explore the opinions and attitudes of MR professionals in the Kingdom of Saudi Arabia (KSA) regarding the current status of routine QA testing within MRI departments.MethodsA qualitative approach was adopted, with MR professionals working in public, semi-public and private hospitals in the KSA invited to participate in this interview-based study. A total of 52 individual semi-structured interviews were conducted with purposive sampling of MR radiographers and medical physicists based at 19 major centres across the three main geographical regions in the KSA. Data went through duration of coding following qualitative data analysis framework based on Miles and Huberman's philosophical underpinnings.ResultsThe findings demonstrated that 89.5% (n = 17) of the MRI departments surveyed rely on the service provided by the equipment vendor in order to ensure ongoing MR scanner performance. Overall, the level of MR radiographer participation in weekly MR scanner QA testing was low (13.3%, n = 3). Lack of legal requirement, professional organisation and knowledge were highlighted as the principal factors limiting radiographer involvement in the weekly MR QA in the KSA.ConclusionThe results of this study support the establishment of a legal requirement and national policy in order to encourage radiographers in the KSA to take an active role in MRI QA testing to enable suboptimal MR scanner performance to be identified before it becomes clinically evident.     

Aortic and innominate routes for transcatheter aortic valve implantation

Objectives

This study aimed at evaluating the efficacy and safety of the transaortic approach for the transcatheter aortic valve implantation procedure using balloon-expandable and self-expanding devices.

The serine-threonine protein phosphatase PPM1D is frequently activated through amplification in aggressive primary breast tumours

Summary The serine–threonine protein phosphatase PPM1D is likely to play an important role in tumorigenesis. Through inactivation of p38 MAPK, PPM1D acts as a negative feedback regulator of p53 tumour suppressor gene and controls the expression of other cell cycle regulatory proteins, such as CCND1. In addition, recent knock-out mouse studies implicated PPM1D in the regulation of p16 expression and the RB tumour suppressor pathway. Here we explored the role of PPM1D aberrations in primary breast cancer. PPM1D copy number analysis showed amplification in 11% (13/117) of the tumours and quantitative real-time RT-PCR revealed a significant correlation (p=0.0148) between PPM1D amplification and increased expression. PPM1D amplification occurred almost exclusively in tumours with wild-type p53 suggesting that these events are mutually exclusive and further confirming the role of PPM1D as a negative regulator of p53. Interestingly, PPM1D amplification was associated with ERBB2 expression (p=0.0001) thus implying that PPM1D aberrations occurs in tumours with poor prognosis. We also explored the expression levels of two possible downstream targets of PPM1D. However, immunohistochemical analyses revealed no differences in the staining patterns of CCND1 and p16 proteins in tumours with or without PPM1D aberrations, thus suggesting that previous data from animal model experiments is not directly transferable to primary human tumours. On the other hand, these key cellular proteins are likely to be regulated through a complex fashion in breast cancer and apparently PPM1D represents only one of these mechanisms. Taken together, our findings substantiate an important role for PPM1D in breast cancer.     

99mTc-PPM应用于肺肿瘤的显像和导向手术的研究

背景与目的:肉眼判断和冰冻切片病理检查是我们在术中判断肿瘤的良恶性及其侵袭范围的常规方法,但肉眼判断缺乏准确性,术中冰冻检查需要等待一段时间;而术中用手持式γ探测仪( gamma detecting probe, GDP)判断肿瘤的浸润范围及转移程度,可以帮助术者快速准确地决定手术切除范围及治疗方案,使手术更加合理化及个体化.本研究以 99mTc 培普利欧霉素( peplomycin,PPM)为肿瘤示踪剂,进行肺癌显像和放射性核素导向手术的初步临床研究.方法:对 37例肺肿瘤患者注射 99mTc PPM,术前进行肺肿瘤的显像,以 ROI(region of interest)法处理并计算 T/NT;术中以手持式γ探测仪 (GDP)对手术标本进行放射性探测,以正常肺组织为本底组织( NT)计算 T/NT比值,以比值的高低来确定探测标本的性质.结果:良、恶性肿瘤对 99mTc PPM的摄取值 (良性病变 N/NT 1.04± 0.08,肺癌 N/NT 1.41±0.16)的差异有统计学意义( P< 0.01) ;以良性病变 T/NT的 x± 2s为判断良恶性病变的阈值, 99mTc PPM显像对肺癌诊断灵敏度为 90%,特异性为 87.5%,准确度为 89.3%;应用 GDP能够准确地探测出肿瘤的侵袭范围,并可以判定肿瘤的淋巴结转移情况,其灵敏度、特异性和准确率分别达到 91.0%、 88.0%和 90.0%.结论:可以将 99mTc PPM作为肿瘤示踪剂对肿瘤进行术前诊断和术中 GDP探测.术中应用 GDP探测,可以有效地判断肺癌的浸润范围及淋巴结转移,对肺癌手术的实施有一定的指导意义.     

TRIM59靶向调控PPM1B对鼻咽癌侵袭和迁移的作用

目的 探讨TRIM59能否通过靶向PPM1B影响鼻咽癌侵袭和迁移。方法 TCGA数据库分析TRIM59在鼻咽癌中的表达;Western blot实验检测TRIM59和PPM1B在鼻咽癌和癌旁组织中的表达情况;RT-PCR和Western blot实验分别检测鼻咽癌细胞系中TRIM59和PPM1B mRNA和蛋白的相对表达量;建立HNE1细胞TRIM59过表达及抑制表达的稳定细胞系,实验设未转染组（Control）、模拟物阴性对照组（mimic NC）、TRIM59 模拟物组（mimic-TRIM59）、抑制剂阴性对照组（inhibitor NC）及TRIM59抑制剂组（si-TRIM59）。Western blot和荧光素酶报告基因实验检测TRIM59和PPM1B靶向关系;Transwell小室检测HNE1细胞侵袭和迁移能力的变化。结果 TCGA数据库结果表明,TRIM59在鼻咽癌组织中的表达明显高于癌旁组织（P= 0.006）;TRIM59在鼻咽癌组织中表达增加（P=0.01）且PPM1B 表达下降（P=0.03）;与HNEpC细胞相比,TRIM59在HNE1细胞中相对表达量显著增加（P=0.04）,PPM1B在HNE1细胞中相对表达量显著下降（P=0.02）;PPM1B为TRIM59下游靶基因且与TRIM59表达呈负相关（P=0.01）;Transwell结果显示,上调TRIM59表达,HNE1细胞侵袭和迁移能力增强（P=0.01,P=0.02）,下调TRIM59表达,HNE1细胞侵袭和迁移能力受到显著抑制（P=0.01）;同时下调TRIM59且上调PPM1B表达后,HNE1细胞侵袭和迁移能力均较单独下调TRIM59表达显著被抑制（P=0.02,P=0.01）。结论 TRIM59通过靶向调控PPM1B影响鼻咽癌细胞侵袭和转移。     

Medulloblastomas overexpress the p53-inactivating oncogene <Emphasis Type="Italic">WIP1/PPM1D</Emphasis>

Medulloblastoma is the most common malignant brain tumor of childhood. Despite numerous advances, clinical challenges range from recurrent and progressive disease to long-term toxicities in survivors. The lack of more effective, less toxic therapies results from our limited understanding of medulloblastoma growth. Although TP53 is the most commonly altered gene in cancers, it is rarely mutated in medulloblastoma. Accumulating evidence, however, indicates that TP53 pathways are disrupted in medulloblastoma. Wild-type p53-induced phosphatase 1 (WIP1 or PPM1D) encodes a negative regulator of p53. WIP1 amplification (17q22-q23) and its overexpression have been reported in diverse cancer types. We examined primary medulloblastoma specimens and cell lines, and detected WIP1 copy gain and amplification prevalent among but not exclusively in the tumors with 17q gain and isochromosome 17q (i17q), which are among the most common cytogenetic lesions in medulloblastoma. WIP1 RNA levels were significantly higher in the tumors with 17q gain or i17q. Immunoblots confirmed significant WIP1 protein in primary tumors, generally higher in those with 17q gain or i17q. Under basal growth conditions and in response to the chemotherapeutic agent, etoposide, WIP1 antagonized p53-mediated apoptosis in medulloblastoma cell lines. These results indicate that medulloblastoma express significant levels of WIP1 that modulate genotoxic responsiveness by negatively regulating p53.     

Identification of differentially expressed genes after PPM1D silencing in breast cancer

Amplification and overexpression of PPM1D (protein phosphatase magnesium-dependent 1 delta) has been observed in various cancer cell lines and primary tumors and has also been associated with cancers of poor prognosis. In addition to the negative feedback regulation of p38-p53 signaling, PPM1D inhibits other tumor suppressor activities and is involved in the control of DNA damage and repair pathways. To elucidate the functional significance of PPM1D in breast cancer, we employed RNA interference to downregulate PPM1D expression in BT-474, MCF7, and ZR-75-1 breast cancer cell lines and then investigated the effects of PPM1D silencing on global gene expression patterns and signaling pathways using oligonucleotide microarrays. We identified 1798 differentially expressed (at least a two-fold change) gene elements with functions related to key cellular processes, such as regulation of cell cycle, assembly of various intracellular structures and components, and regulation of signaling pathways and metabolic cascades. For instance, genes involved in apoptosis (NR4A1, RAB25, PLK1), formation of nucleosome structure (HIST1H2AC, HIST1H2BF, HIST1H2BO, HIST1H1D), and hormone related activities (NR4A1, ESR1, STC1) were among the differentially expressed genes. Overall, our findings suggest that PPM1D contributes to breast cancer associated phenotypic characteristics by directly or indirectly affecting several important cellular signaling pathways.     

PPM EMAT for Defect Detection in 90-Degree Pipe Bend

Aircraft pipelines are mainly used for the storage and transportation of fuel, hydraulic oil and water, which are mostly bent pipes of non-ferromagnetic materials. We used PPM (Periodic Permanent Magnet) EMAT (Electromagnetic Acoustic Transducer) to detect the defects at 90-degree bends. A simulation model was established by finite element software to study the propagation characteristics and defect detection capability of T (0, 1) mode-guided wave in aluminum pipe bend. In terms of propagation characteristics, the energy of the guided wave was focused in the extrados of the bend, and the guided waves in the intrados and extrados of the bend were separated due to the difference in propagation distance. Regarding defect detection capability, T (0, 1) mode-guided wave had the highest detection sensitivity for the defect in the extrados of the bend and the lowest detection sensitivity for the defect in the middle area of the bend. We designed a PPM EMAT for 320 kHz to verify the simulation results experimentally, and the experimental results are in good agreement with the simulation results.