Clinical outcome of pediatric medulloblastoma patients with Li-Fraumeni syndrome

BACKGROUND

The prognosis for Li-Fraumeni syndrome (LFS) patients with medulloblastoma (MB) is poor. Comprehensive clinical data for this patient group is lacking, challenging the development of novel therapeutic strategies. Here, we present clinical and molecular data on a retrospective cohort of pediatric LFS MB patients.

METHODS

In this multinational, multicenter retrospective cohort study, LFS patients under 21 years with MB and class 5 or class 4 constitutional TP53 variants were included. TP53 mutation status, methylation subgroup, treatment, progression free- (PFS) and overall survival (OS), recurrence patterns, and incidence of subsequent neoplasms were evaluated.

RESULTS

The study evaluated 47 LFS individuals diagnosed with MB, mainly classified as DNA methylation subgroup "SHH_3" (86%). The majority (74%) of constitutional TP53 variants represented missense variants. The 2- and 5-year (y-) PFS were 36% and 20%, and 2- and 5y-OS were 53% and 23%, respectively. Patients who received postoperative radiotherapy (RT) (2y-PFS: 44%, 2y-OS: 60%) or chemotherapy before RT (2y-PFS: 32%, 2y-OS: 48%) had significantly better clinical outcome then patients who were not treated with RT (2y-PFS: 0%, 2y-OS: 25%). Patients treated according to protocols including high-intensity chemotherapy and patients who received only maintenance-type chemotherapy showed similar outcomes (2y-PFS: 42% and 35%, 2y-OS: 68% and 53%, respectively).

CONCLUSIONS

LFS MB patients have a dismal prognosis. In the presented cohort use of RT significantly increased survival rates, whereas chemotherapy intensity did not influence their clinical outcome. Prospective collection of clinical data and development of novel treatments are required to improve the outcome of LFS MB patients.

Recurrent TRAK1::RAF1 Fusions in pediatric low-grade gliomas

Fusions involving CRAF (RAF1) are infrequent oncogenic drivers in pediatric low-grade gliomas, rarely identified in tumors bearing features of pilocytic astrocytoma, and involving a limited number of known fusion partners. We describe recurrent TRAK1::RAF1 fusions, previously unreported in brain tumors, in three pediatric patients with low-grade glial-glioneuronal tumors. We present the associated clinical, histopathologic and molecular features. Patients were all female, aged 8 years, 15 months, and 10 months at diagnosis. All tumors were located in the cerebral hemispheres and predominantly cortical, with leptomeningeal involvement in 2/3 patients. Similar to previously described activating RAF1 fusions, the breakpoints in RAF1 all occurred 5' of the kinase domain, while the breakpoints in the 3' partner preserved the N-terminal kinesin-interacting domain and coiled-coil motifs of TRAK1. Two of the three cases demonstrated methylation profiles (v12.5) compatible with desmoplastic infantile ganglioglioma (DIG)/desmoplastic infantile astrocytoma (DIA) and have remained clinically stable and without disease progression/recurrence after resection. The remaining tumor was non-classifiable; with focal recurrence 14 months after initial resection; the patient remains symptom free and without further recurrence/progression (5 months post re-resection and 19 months from initial diagnosis). Our report expands the landscape of oncogenic RAF1 fusions in pediatric gliomas, which will help to further refine tumor classification and guide management of patients with these alterations.

[Current status of influencing factors for postoperative anastomotic leakage in low rectal cancer]

The incidence of anastomotic leakage, a common and serious postoperative complication of low rectal cancer, remains high. Clarifying the risk factors for anastomotic leakage in patients with low rectal cancer after surgery can help guide clinical treatment and help patients improve their prognosis. The current literature suggests that the risk factors affecting the occurrence of anastomotic leakage after low rectal cancer include three aspects: (1) individual factors: male gender, high body mass index, malnutrition, smoking, alcoholism, and metabolic diseases; (2) tumor factors: the lower margin of tumor <5 cm from the anal verge, tumor diameter >2.5 cm, late tumor stage, high level of tumor markers and preoperative intestinal obstruction; (3) surgical factors: long operative time (>180 min), intraoperative bleeding (≥70 ml), more than 2 cartridges of stapling for anastomosis, contamination of the operative field, epidural analgesia and intraoperative hypothermia. Notably, the surgical approach (laparoscopic, open and hand-assisted laparoscopic surgery) was not a factor influencing the occurrence of postoperative anastomotic leakage in low rectal cancer. The findings on the effects of receiving neoadjuvant therapy, gut microbiota,intestinal bowel preparation, insufficient time for preoperative antibiotic prophylaxis, left colonic artery dissection, intraoperative blood transfusion, pelvic drainage, transanal drainage and combined organ resection, and postoperative diarrhea on postoperative anastomotic leakage in low rectal cancer are controversial. However, clinical workers can still take measures to reduce the risk of anastomotic leakage according to the above risk factors by making a good assessment before surgery, actively avoiding them during and after surgery, and taking measures for each step, so as to bring maximum benefits to patients.

YAP1-MAML2 fusion in a pediatric NF2-wildtype intraparenchymal brainstem schwannoma

Biallelic inactivation of NF2 represents the primary or sole oncogenic driver event in the vast majority of schwannomas. We report on a four-year-old female who underwent subtotal resection of a right medullary intraparenchymal schwannoma. RNA sequencing revealed an in-frame fusion between exon 5 of YAP1 and exon 2 of MAML2. YAP1-MAML2 fusions have previously been reported in a variety of tumor types, but not schwannomas. Our report expands the spectrum of oncogenic YAP1 gene fusions an alternative to NF2 inactivation to include sporadic schwannoma, analogous to what has recently been described in NF2-wildtype pediatric meningiomas. Appropriate somatic and germline molecular testing should be undertaken in all young patients with solitary schwannoma and meningioma given the high prevalence of an underlying tumor predisposition syndrome. In such patients, the identification of a somatic non-NF2 driver alteration such as this newly described YAP1 fusion, can help ascertain the diagnosis of a sporadic schwannoma.

PATH-15. Molecular and clinical landscape of CNS tumors arising among adolescents and young adults (AYA) at Memorial Sloan Kettering Cancer Center (MSKCC): a single-institutional experience

BACKGROUND: The management of CNS tumors arising among AYA represents an unmet challenge. Treatment may be split between pediatric and adult centers, often with conflicting approaches. Biology also appears to be distinct compared to younger/older age groups but has yet to be fully characterized. Such features would have important implications for prognostication and informing vulnerabilities for targeted therapies.METHODS: To establish the clinical and molecular landscape of these tumors, we analyzed all cases in patients aged 15-39 years old who were treated at MSKCC between 2018-2021. RESULTS: 302 patients with accompanying MSK-IMPACT targeted sequencing, copy number analysis, Archer fusion panel, and clinical data were found. 239/302 cases (79%) were gliomas, with the remaining consisting mainly of neuro-epithelial tumors (n=15; 5%), meningiomas (9; 3%), ependymomas (10; 3%), and embryonal tumors (7; 2%). Among gliomas, 163/239 (68%) had IDH1/2 mutations, which were significantly more enriched for TP53 (121/163; 74%) and ATRX (90/163; 55%) co-mutations compared to IDH-wild type (IDH-WT) (q&lt;0.0001). In comparison, IDH-WT gliomas (n=76) were enriched for alterations in BRAF (16/76 with SNV, 9/76 fusion; q&lt;0.0001), H3F3A (14/76; q&lt;0.0001), PTEN (10/76; q=0.038), and CDKN2A (16/76; q=0.038). Among 113 patients with high-grade gliomas (WHO grade 3/4), those with IDH-WT tumors (n=34) had a poorer prognosis that those with IDH-mutant tumors (n=79) (1 and 5-year OS of 68% and 28% vs. 97% and 76%, respectively) (p&lt;0.0001). Further, a lower frequency of alterations in TERT (26/113; 23%), EGFR (6/113; 5%), and PDGFRA (4/113; 4%) were observed compared to previous studies for adult-only cohorts (~50-70%, 40%, and 10%, respectively). CONCLUSIONS: IDH-mutant gliomas were the most common tumor type seen in this AYA cohort. However, some alterations characteristic of adult high-grade gliomas (TERT, EGFR, PDGFRA) were not as frequently observed. Additional identification of molecular features that predict response to conventional and targeted therapies is underway.

Pediatric Pineoblastoma: A pooled outcome study of North American and Australian therapeutic data

Background

Pineoblastoma is a rare brain tumor usually diagnosed in children. Given its rarity, no pineoblastoma specific trials have been conducted. Studies have included pineoblastoma accruing for other embryonal tumors over the past 30 years. These included only occasional children with pineoblastoma, making clinical features difficult to interpret and determinants of outcome difficult to ascertain.

Patients and Methods

Centrally or independently reviewed series with treatment and survival data from North American and Australian cases were pooled. To investigate associations between variables, Fisher’s exact tests, Wilcoxon-Mann-Whitney tests, and Spearman correlations were used. Kaplan-Meier plots, log-rank tests, and Cox proportional hazards models were used in survival analyses.

Results

We describe a pooled cohort of 178 pineoblastoma cases from Children’s Oncology Group (n=82) and institutional series (n=96) over 30 years. Children &lt;3 years of age have significantly worse survival compared to older children, with 5-year progression free survival and overall survival estimates of 13.5±5.1% and 16.2±5.3% respectively compared with 60.8±5.6% and 67.3±5.0% for ≥3 years old (both p&lt;0.0001). Multivariable analysis showed male sex was associated with worse PFS in children &lt;3 years of age (Hazard Ratio 3.93, 95% CI 1.80-8.55; p=0.0006), suggestive of sex specific risks needing future validation. For children ≥3 years of age, disseminated disease at diagnosis was significantly associated with an inferior 5-year PFS of 39.2±9.7% (HR 2.88, 95% CI 1.52-5.45; p=0.0012) and 5-year OS of 49.8±9.1% (HR 2.87, 95% CI 1.49-5.53; p=0.0016).

Conclusion

Given the rarity of this tumor, prospective, collaborative international studies will be vital to improving the long-term survival of these patients.

[Treatment strategy of gastrointestinal stromal tumors in the background of COVID-19]

COVID-19, caused by SARS-COV-2, has the characteristics of world epidemic, highly infectious and large base of death. In China, transmission route of SARS-COV-2 has been contained so effectively that COVID-19 has been well controlled due to the proactive national prevention and control strategy. However, not only does it bring a huge impact on the existing medical structure model, but also an objective impact on the treatment of patients with chronic diseases such as malignant tumors. Based on the progress reported in the domestic and international literatures and the actual management experience of our team, this paper reflects on the treatment strategies for patients with gastrointestinal stromal tumor (GIST) during the epidemic period of COVID-19. We focus on risk stratification for primary GIST and forming treatment strategies accordingly. Major considerations include the impact of delayed operation, the burden of medical resources, the waiting time for elective operation, and the principle of emergency operation. In addition, we focus on the level of evidence for non-surgical approaches with a view to developing a holistic strategy of "priority management principles" to guide clinical treatment in the context of limited resources and different GIST priorities.

[Anatomical controversies involved in radical resection of rectal cancer]

The concept of total mesorectal resection provides a quality control standard that can be followed for radical resection of rectal cancer, but some anatomical problems are still controversial. Compared with traditional open surgery, laparoscopic radical rectal surgery has better surgical vision, better neurological protection, better operating space. However, if the surgeon has insufficient understanding of the anatomy, collateral damage may occur, such as uncontrollable bleeding during the operation, postoperative urination and defecation dysfunction and so on. Based on the interpretation of the researches at home and abroad, combined with the clinical experience, we elucidate some associated issues, including anatomic variation of inferior mesenteric vessels, the controversy of inferior mesenteric artery ligation plane, the controversy of lymph node dissection in No. 253, the anatomical variation of middle rectal artery, and the anatomical controversy of lateral lymph node dissection in rectal cancer, in order to provide better cognitive process for the clinical front-line surgeons.

PATH-24. MOLECULAR CLASSIFICATION OF HIGH RISK INFANT EMBRYONAL BRAIN TUMORS ENROLLED IN THE ACNS0334 TRIAL: A REPORT FROM THE CHILDREN’S ONCOLOGY GROUP

Young children with embryonal brain tumors including medulloblastoma (MB), supratentorial primitive neuro-ectodermal tumor, or pineoblastoma have historically been considered high-risk patients with poor outcomes despite the use of intensive radiation-sparing treatment. In the ACNS0334 phase III trial, 91 consented children <36 months old with the above diagnoses were randomized to intensive induction chemotherapy with or without methotrexate followed by consolidation with stem cell rescue. Here we present the results of a centralized integrated molecular analysis including global methylation profiling (65/91), and whole exome sequencing of tumor (46/91) and germline (35/91) DNA. Unsupervised clustering analyses of methylation profiles using multiple orthogonal methods against a reference dataset of 1200 pediatric brain tumors, revealed known and new molecular entities. For tumors diagnosed as MB on central pathology review, 7.3% (3/41) had a non-MB molecular diagnosis (2 embryonal tumor with multiple rosettes/ETMR, 1 group MYC pineoblastoma), with the remainder as MB Group SHH (11/41), Group3 (25/41), and Group4 (2/41). Among histologic non-MBs, 3/24 (12.5%) were molecular entities not intended for trial inclusion (1 each for ATRT, pleomorphic xanthoastrocytoma, and high-grade glioma). ETMR, historically considered a rare entity, was molecularly identified in a significant proportion (14/65; 21.5%) of samples. Among MB-SHH, we detected deleterious PTCH1 mutations in 6/9 tumors but none among 5 germline samples tested; a germline SUFU frameshift mutation with tumor LOH was also observed in MB-SHH. Correlation of these and other molecular features to the parallel clinical analysis will yield important markers of risk stratification and predictors of treatment response.

ETMR-21. META-ANALYSIS OF PINEAL REGION TUMOURS DEMONSTRATES MOLECULAR SUBGROUPS WITH DISTINCT CLINICO-PATHOLOGICAL FEATURES: A CONSENSUS STUDY

Pineoblastomas (PB) are rare, aggressive pineal gland tumours with poor global OS of 50–70% and only 15–49% OS for patients <4 years, despite intensive treatments. Recently, three independent groups (German Cancer Research Centre, Rare Brain Tumour Consortium/SickKids, St. Jude Children’s Research Hospital) collectively analyzed large tumour cohorts and revealed molecular sub-groups of PB. To harmonize and better characterize clinico-pathologic associations of these sub-groups, we undertook a meta-analysis of molecular and clinical data of the combined cohorts. Unsupervised consensus cluster analyses of global methylation data from 227 unique cases identified five robust molecular sub-groups of pineal region tumours: PB_miRNA_1, PB_miRNA_2, PB_MYC/FOXR2, and PB_RB, mainly comprised of pediatric WHO grade 4 PBs and PNETs; and a fifth group: named PPTID, comprised of mainly pineal parenchymal tumours of intermediate differentiation, a WHO grade 2–3 tumour common in adults. PB_miRNA_1 and PB_miRNA_2 tumours, primarily arising in children (median ages 7.7, 11.4y, respectively), were characterized by alterations of miRNA biogenesis genes DICER1, DROSHA, and DGCR8. PB_MYC/FOXR2 and PB_RB groups, arising in infants/toddlers (median ages 1.4, 2.0y, respectively), were distinguished by recurrent MYC gain/amplification and RB1 loss, respectively. The PPTID group affected mainly adults (median age 33y) and exhibited limited CNAs. Higher rates of metastasis were observed with PB_miRNA_1 (42%), PB_MYC/FOXR2 (38%), and PB_RB (75%) tumours, compared to PB_miRNA_2 (20%) and PPTID (25%). Results from ongoing integrative survival analyses of this large cohort will provide critical data for design of future clinical trials.

[Treatment strategies for colorectal cancer patients in tumor hospitals under the background of corona virus disease 2019]

In December 2019, a new outbreak of corona virus disease 2019 began to occur. Its pathogen is 2019-nCoV, which has the characteristics of strong infectivity and general susceptibility. The current situation of prevention and control of new coronavirus pneumonia is severe. In this context, as front-line medical workers bearing important responsibilities and pressure, while through strict management strategy, we can minimize the risk of infection exposure. By summarizing the research progress and guidelines in recent years in the fields of colorectal cancer disease screening, treatment strategies (including early colorectal cancer, locally advanced colorectal cancer, obstructive colorectal cancer, metastatic colorectal cancer and the treatment of patients after neoadjuvant therapy), the choice of medication and time limit for adjuvant therapy, the protective measures for patients undergoing emergency surgery, the re-examination of postoperative patients and the protection of medical staff, etc., authors improve treatment strategies in order to provide more choices for patients to obtain the best treatment under the severe epidemic situation of new coronavirus pneumonia. Meanwhile we hope that it can also provide more timely treatment modeling schemes for colleagues.

[Thinking of treatment strategies for colorectal cancer patients in tumor hospitals under the background of coronavirus pneumonia]

In December 2019, a new outbreak of coronavirus pneumonia began to occur. Its pathogen is 2019-nCoV, which has the characteristics of strong infectivity and general susceptibility. The current situation of prevention and control of new coronavirus pneumonia is severe. In this context, as front-line medical workers bearing important responsibilities and pressure, while through strict management strategy, we can minimize the risk of infection exposure. By summarizing the research progress and guidelines in recent years in the fields of colorectal cancer disease screening, treatment strategies(including early colorectal cancer, locally advanced colorectal cancer, obstructive colorectal cancer, metastatic colorectal cancer and the treatment of patients after neoadjuvant therapy), the choice of medication and time limit for adjuvant therapy, the protective measures for patients undergoing emergency surgery, the re-examination of postoperative patients and the protection of medical staff, etc., authors improve treatment strategies in order to provide more choices for patients to obtain the best treatment under the severe epidemic situation of new coronavirus pneumonia. Meanwhile we hope that it can also provide more timely treatment modeling schemes for colleagues.

Pineoblastoma segregates into molecular sub-groups with distinct clinico-pathologic features: a Rare Brain Tumor Consortium registry study

Pineoblastomas (PBs) are rare, aggressive pediatric brain tumors of the pineal gland with modest overall survival despite intensive therapy. We sought to define the clinical and molecular spectra of PB to inform new treatment approaches for this orphan cancer. Tumor, blood, and clinical data from 91 patients with PB or supratentorial primitive neuroectodermal tumor (sPNETs/CNS-PNETs), and 2 pineal parenchymal tumors of intermediate differentiation (PPTIDs) were collected from 29 centres in the Rare Brain Tumor Consortium. We used global DNA methylation profiling to define a core group of PB from 72/93 cases, which were delineated into five molecular sub-groups. Copy number, whole exome and targeted sequencing, and miRNA expression analyses were used to evaluate the clinico-pathologic significance of each sub-group. Tumors designated as group 1 and 2 almost exclusively exhibited deleterious homozygous loss-of-function alterations in miRNA biogenesis genes (DICER1, DROSHA, and DGCR8) in 62 and 100% of group 1 and 2 tumors, respectively. Recurrent alterations of the oncogenic MYC-miR-17/92-RB1 pathway were observed in the RB and MYC sub-group, respectively, characterized by RB1 loss with gain of miR-17/92, and recurrent gain or amplification of MYC. PB sub-groups exhibited distinct clinical features: group 1-3 arose in older children (median ages 5.2-14.0 years) and had intermediate to excellent survival (5-year OS of 68.0-100%), while Group RB and MYC PB patients were much younger (median age 1.3-1.4 years) with dismal survival (5-year OS 37.5% and 28.6%, respectively). We identified age < 3 years at diagnosis, metastatic disease, omission of upfront radiation, and chr 16q loss as significant negative prognostic factors across all PBs. Our findings demonstrate that PB exhibits substantial molecular heterogeneity with sub-group-associated clinical phenotypes and survival. In addition to revealing novel biology and therapeutics, molecular sub-grouping of PB can be exploited to reduce treatment intensity for patients with favorable biology tumors.

Pediatric embryonal brain tumors in the molecular era

Introduction: Embryonal brain tumors (EBTs) are highly aggressive malignancies predominantly affecting children. They include medulloblastoma (MB), atypical rhabdoid/teratoid tumors (ATRT), pineoblastoma (PB), embryonal tumor multiple rosettes (ETMR)/C19MC-altered tumors, and newly recognized embryonal tumors with FOXR2 activation or BCOR alteration.Areas covered: This review will provide a comprehensive overview and updated of the literature on each of these EBTs. The evolution from location- and histopathology-based diagnosis to more specific and robust molecular-based classification schemes, as well as treatment modalities, will be discussed.Expert commentary: The subgrouping of EBTs with multi-omic profiling has had important implications for risk stratification and discovery of targetable driver pathways. However, these innovations are unlikely to significantly improve survival among high-risk patients until robust preclinical studies are conducted, followed by validation in biology-informed clinical trials.

Investigation of an InP-based image converter with optical excitation

An image converter based on an indium phosphide has been developed to measure the two-dimensional spatial profile of the incident photon flux by probing the rapid change of the refractive index in the semiconductor. The spatial resolution, dynamic range, and temporal response of this image converter have been investigated with optical methods. The results show that the spatial resolution is ∼15 cycles/mm at the percent modulation transfer function of 0.5, the dynamic range is about 100, and the time response is in the order of 600 ps. This scheme can provide an alternative choice as an imaging diagnostic for experiments in the area of high-energy density physics.

Surveillance imaging and radiation exposure in the detection of relapsed neuroblastoma

BACKGROUND

More than half of children with high-risk neuroblastoma (NB) will experience recurrence. Radiologic imaging is used for initial staging and during therapy to assess response. However, the role of surveillance imaging in the detection of relapse has not been well studied. Surveillance potentially results in high cumulative exposure to ionizing radiation, which may be associated with an increased risk of developing second malignancies.

PROCEDURE

We reviewed NB cases at our institution between 2000 and 2011. We calculated radiation exposure due to imaging (during diagnosis, treatment, and posttherapy surveillance) using cumulative effective dose (CED) estimates and determined whether cross-sectional imaging identified recurrences.

RESULTS

Fifty of 183 patients with NB experienced a recurrence. The median time from diagnosis to relapse was 1.20 years (range: 0.18-6.66 years). Most patients had evidence of metastases and only 4 of 50 patients presented with isolated primary tumor site recurrences. The mean CED prior to relapse was 125.2 mSv (range: 24.5-259.7), 64% of which was from computed tomography (CT) scans. Thirty-seven of 50 patients had clinically evident or measurable disease detected by X-ray (XR), ultrasound (US), or urinary catecholamines (UCats), and the addition of metaiodobenzylguanidine (MIBG) scans identified eight additional recurrences. Thus, cross-sectional imaging (CT/MRI, where MRI is magnetic resonance imaging) was only required to identify 10% (5/50) of cases.

CONCLUSION

Relapsed disease was detected in most patients by symptoms/exam, MIBG scan, UCats, and/or XR/US, supporting reduced use of CT imaging in posttherapy surveillance, thereby decreasing cumulative radiation dose. Refinement of surveillance imaging may be further guided by risk stratification, disease sites, and potentially biomolecular markers.

Influence of suppression of CapG gene expression by siRNA on the growth and metastasis of human prostate cancer cells

This study investigated CapG gene expression in prostate cancer cell lines; in addition, we explored the effects of CapG suppression on DU145 cell growth, and the underlying mechanism with which CapG affects DU145 cell growth and invasiveness. The expression of CapG and 18 related genes in DU145 cells was analyzed by flow cytometry, quantitative polymerase chain reaction (qPCR), CCK8 assay, western blot, and the trans-well assay. DU145 cells were transfected with designed small interfering RNA (siRNA). CapG expression was quantified by qPCR and western blot. DU145 cell proliferation and invasiveness was analyzed using the CCK8, flow cytometric, and trans-well assays. CapG, TMPRSS1, EGFR, ETS-1, ERBB2, AKT, Cyclin D1, P21, Bcl-2, and Bak1 gene and Bcl-2, Cyclin D1, and CapG protein expressions were significantly lower in the siRNA group compared to the negative control group (P < 0.05). The proliferation of CapG siRNA DU145 cells was lower than that of the two control groups, 48 h after transfection. The cell inhibition rate was 24.5, 35.4, and 16,5% at 24, 48, and 72 h, respectively. The growth curve indicated that CapG siRNA DU145 cells showed a significantly slower proliferation rate (P < 0.05). The trans-well assay showed a significant decrease in the migratory and invasive capacities of DU145 cells in the siRNA group (P < 0.05). The suppression of CapG expression caused a significant decrease in the proliferation, invasiveness, and metastasis of DU145 cells. The mechanism with which CapG, with other oncogenes, influences cancer cell cycle remains to be elucidated.

Clinical and genetic characterization of complete androgen insensitivity syndrome in a Chinese family

We studied a family with two cousins who were diagnosed with complete androgen insensitivity syndrome, an X-linked disorder caused by mutations in the androgen receptor gene. A pedigree analysis and a molecular study using PCR and DNA sequencing clarified each female family member's androgen receptor status and revealed a mutation consisting of the deletion of exon 2 and surrounding introns of the androgen receptor gene. Based on the relative nucleotide positions, we concluded that the deletion mutation in exon 2 and its surrounding introns was approximately 6000 to 7000 bp. This mutation, never previously fully characterized using DNA sequencing, was responsible for complete androgen insensitivity syndrome in this family. Pedigree analysis with a molecular study of the androgen receptor gene in affected families facilitates genetic counseling provided to family members.

Image reconstructions with the rotating RF coil

Recent studies have shown that rotating a single RF transceive coil (RRFC) provides a uniform coverage of the object and brings a number of hardware advantages (i.e. requires only one RF channel, averts coil-coil coupling interactions and facilitates large-scale multi-nuclear imaging). Motion of the RF coil sensitivity profile however violates the standard Fourier Transform definition of a time-invariant signal, and the images reconstructed in this conventional manner can be degraded by ghosting artifacts. To overcome this problem, this paper presents Time Division Multiplexed-Sensitivity Encoding (TDM-SENSE), as a new image reconstruction scheme that exploits the rotation of the RF coil sensitivity profile to facilitate ghost-free image reconstructions and reductions in image acquisition time. A transceive RRFC system for head imaging at 2 Tesla was constructed and applied in a number of in vivo experiments. In this initial study, alias-free head images were obtained in half the usual scan time. It is hoped that new sequences and methods will be developed by taking advantage of coil motion.

Abstract B1: Chemotherapy induces NEDP1-mediated destabilization of MDM2

MDM2 is an E3 ligase that promotes ubiquitin-mediated destruction of p53. Cellular stresses such as DNA damage can lead to p53 activation due in part to MDM2 destabilization. Here, we show that the stability of MDM2 is regulated by an ubiquitin-like NEDD8 pathway and identify NEDP1 as a chemotherapy-induced isopeptidase that deneddylates MDM2, resulting in MDM2 destabilization concomitant with p53 activation. Concordantly, RNA-imediated knockdown of endogenous NEDP1 blocked diminution of MDM2 levels and increased chemoresistance of tumor cells. These findings unveil the regulation of MDM2 stability via NEDP1 as a common molecular determinant governing chemotherapy-induced p53-dependent cell death.

Citation Information: Cancer Res 2009;69(23 Suppl):B1.

An efficient BiCGstab solved impedance method for induced field evaluation with a hyperthermia applicator

This paper presents a stabilized Bi-conjugate gradient algorithm that can significantly improve the performance of the impedance method, which has been widely applied to model low-frequency field induction phenomena in voxel phantoms. The improved quasi-static impedance method offers remarkable computational advantages in terms of convergence performance and memory consumption over the conventional, stationary iterative method-based algorithm. The scheme has been validated against other numerical/analytical solutions on a lossy, multilayered sphere phantom with an ideal coil loop excitation. To further demonstrate the computational performance and application capability of the developed algorithm, the induced fields inside a whole body human phantom responding to hyperthermia device was evaluated. The simulation results show the numerical accuracy and superior performance of the method.

An inverse methodology for high frequency RF head coil design with preemphasized B/sub 1/ field in MRI

An inverse methodology to assist in the design of radio-frequency (RF) head coils for high field MRI application is described in this work. Free space time-harmonic electromagnetic Green's functions and preemphasized B/sub 1/ field are used to calculate the current density on the coil cylinder. With B/sub 1/ field preemphasized and lowered in the middle of the RF transverse plane, the calculated current distribution can generate an internal magnetic field that can reduce the EM field/tissue interactions at high frequencies. The current distribution of a head coil operating at 4 T is calculated using inverse methodology with preemphasized B/sub 1/ fields. FDTD is employed to calculate B/sub 1/ field and signal intensity inside a homogenous cylindrical phantom and human head. A comparison with conventional RF birdcage coil is reported here and demonstrated that inverse-method designed coil with preemphasized B/sub 1/ field can help in decreasing the notorious bright region caused by EM field/tissue interactions in the human head images at 4 T.

A New Decoupling Method for Quadrature Coils in Magnetic Resonance Imaging

A powerful decoupling method is introduced to obtain decoupled signal voltages from quadrature coils in magnetic resonance imaging (MRI). The new method uses the knowledge of the position of the signal source in MRI, the active slice, to define a new mutual impedance which accurately quantifies the coupling voltages and enables them to be removed almost completely. Results show that by using the new decoupling method, the percentage errors in the decoupled voltages are of the order of 10(-7) % and isolations between two coils are more than 170 dB.