Energy decomposition and waterswapping analysis to investigate the SNP associated DPD mediated 5-FU resistance

5-fluorouracil is an essential component of systemic chemotherapy for colon, breast, head, and neck cancer patients. However, tumoral overexpression of the dihydropyrimidine dehydrogenase has rendered 5-FU clinically ineffective by inactivating it to 5'-6'-dihydro fluorouracil. The responses to 5-FU in terms of efficacy and toxicity greatly differ depending upon the population group, because of variability in the DPD activity levels. In the current study, key active site amino acids involved in the 5-FU inactivation were investigated by modelling the 3D structure of human DPD in a complex with 5-FU. The identified amino acids were analyzed for their possible missense mutations available in dbSNP database. Out of 12 missense SNPs, four were validated either by sequencing in the 1000 Genomes project or frequency/genotype data. The recorded validated missense SNPs were further considered to analyze the effect of their respective alterations on 5-FU binding. Overall findings suggested that population bearing the Glu611Val DPD mutation (rs762523739) is highly vulnerable to 5-FU resistance. From the docking, electrostatic complementarity, dynamics, and energy decomposition analyses it was found that the above mutation showed superior scores than the wild DPD -5FU complex. Therefore, prescribing prodrug NUC-3373 or DPD inhibitors (Gimeracil/3-Cyano-2,6-Dihydroxypyridines) as adjuvant therapy may overcome the 5-FU resistance.

LGG-45. Genetic dependencies inMYB/MYBL1-driven pediatric low-grade glioma models

AIM: Pediatric low-grade gliomas (pLGGs) are a heterogenous group of tumors, diverse in their localization, histology, mutational landscape, clinical behavior, and treatment response. Genomic alterations impacting the MYB family of transcription factors were identified in two distinct pLGG subtypes: Angiocentric Gliomas (AG) and Diffuse Astrocytomas (DA). The molecular profiles and therapeutic vulnerabilities associated with these genomic alterations remain unexplored. In this study we highlight the use of genome-wide CRISPR/Cas9 knock-out screens for an unbiased identification of translatable therapeutic targets. METHODOLOGY: Given the lack of patient-derived pLGG cell lines, we engineered in vitro pLGG mouse and human neural stem cell (NSC) models to harbor pLGG-relevant genomic alterations. We performed single cell RNA sequencing to investigate the transcriptional profiles driven by these mutations and to dissect the central regulatory networks enabling tumorigenesis. Specific genetic dependencies associated with MYB/MYBL1 mutations were screened using the Brie genome-wide mouse CRISPR lentiviral knock-out pooled library, consisting of 78,637 single guide RNAs (sgRNAs) targeting 19,674 mouse genes. RESULTS: We have successfully generated in vitro NSC-based pLGG models crucial to deepening our knowledge on pLGG biology and the identification of translatable therapeutic targets. Genome-scale CRISPR/Cas9 knock-out screens in isogenic NSCs models, expressing distinct MYB/MYBL1 alterations or a control transgene, revealed several differential genetic dependencies. Among the top identified dependencies are regulators of cell-stress response, cell-cycle progression, and modulators of the ubiquitin-proteasome degradation pathway. CONCLUSION: Genome-wide CRISPR knock-out screens are a powerful tool for the unbiased identification of mutation-specific genetic dependencies that can be explored as candidates for precision medicine approaches.

Tau pathology mediates age effects on medial temporal lobe structure

Hippocampal atrophy is endemic in 'normal aging' but it is unclear what factors drive age-related changes in medial temporal lobe (MTL) structural measures. We investigated cross-sectional (n = 191) and longitudinal (n = 164) MTL atrophy patterns in cognitively normal older adults from ADNI-GO/2 with no to low cerebral β-amyloid and assessed whether white matter hyperintensities (WMHs) and cerebrospinal fluid (CSF) phospho tau (p-tau) levels can explain age-related changes in the MTL. Age was significantly associated with hippocampal volumes and Brodmann Area (BA) 35 thickness, regions affected early by neurofibrillary tangle pathology, in the cross-sectional analysis and with anterior and/or posterior hippocampus, entorhinal cortex and BA35 in the longitudinal analysis. CSF p-tau was significantly associated with hippocampal volumes and atrophy rates. Mediation analyses showed that CSF p-tau levels partially mediated age effects on hippocampal atrophy rates. No significant associations were observed for WMHs. These findings point toward a role of tau pathology, potentially reflecting Primary Age-Related Tauopathy, in age-related MTL structural changes and suggests a potential role for tau-targeted interventions in age-associated neurodegeneration and memory decline.

LGG-35. FUNCTIONAL GENOMIC APPROACHES TO IDENTIFY THERAPEUTIC TARGETS IN MYB AND MYBL1 EXPRESSING PEDIATRIC LOW-GRADE GLIOMAS

AIM

Recurrent structural variants involving MYB and MYBL1 transcription factors were recently identified in pediatric low-grade gliomas (pLGGs), such as the MYB-QKI rearrangement in Angiocentric Gliomas and truncations of MYBL1 (MYBL1tr) in Diffuse Astrocytomas. However, therapeutic dependencies induced by these alterations remain unexplored.

METHODOLOGY

We have generated in vitro pLGG mouse neural stem cell (NSCs) models engineered to harbor distinct MYB/MYBL1 genomic alterations. We used single cell RNA sequencing approaches to determine the transcriptional profile and dissect the central regulatory networks of our in vitro pLGG models over time. To identify specific genetic dependencies associated with MYB/MYBL1 mutations, we employed the Brie genome-wide mouse CRISPR lentiviral knockout pooled library, consisting of 78,637 single guide RNAs (sgRNAs) targeting 19,674 mouse genes.

RESULTS

MYB/MYBL1 expression in neural stem cells induced activation of cell-cycle related, glioma-related and senescence-related pathways that are involved in normal development, including activation of MAPK and mTOR signaling which are also activated in human pLGG samples. Genome-scale CRISPR-cas9 screens in isogenic NSCs expressing MYB-QKI or MYBL1tr identified differential genetic dependencies relative to GFP controls. These included regulators of cell-cycle progression and several modulators of the ubiquitin-proteasome degradation pathway. Analysis of RNA-sequencing data from human tumors revealed several of these dependencies identified in the cell line model to be differentially expressed in MYB-altered pLGG tumors relative to normal brain.

CONCLUSION

Expression of MYB family alterations induces expression of key developmental and oncogenic pathways and genetic dependencies that represent potential therapeutic targets for MYB or MYBL1 rearranged pLGGs.

Neurobiological support to the diagnosis of ADHD in stimulant-naïve adults: pattern recognition analyses of MRI data

OBJECTIVE

In adulthood, the diagnosis of attention-deficit/hyperactivity disorder (ADHD) has been subject of recent controversy. We searched for a neuroanatomical signature associated with ADHD spectrum symptoms in adults by applying, for the first time, machine learning-based pattern classification methods to structural MRI and diffusion tensor imaging (DTI) data obtained from stimulant-naïve adults with childhood-onset ADHD and healthy controls (HC).

METHOD

Sixty-seven ADHD patients and 66 HC underwent high-resolution T1-weighted and DTI acquisitions. A support vector machine (SVM) classifier with a non-linear kernel was applied on multimodal image features extracted on regions of interest placed across the whole brain.

RESULTS

The discrimination between a mixed-gender ADHD subgroup and individually matched HC (n = 58 each) yielded area-under-the-curve (AUC) and diagnostic accuracy (DA) values of up to 0.71% and 66% (P = 0.003) respectively. AUC and DA values increased to 0.74% and 74% (P = 0.0001) when analyses were restricted to males (52 ADHD vs. 44 HC).

CONCLUSION

Although not at the level of clinically definitive DA, the neuroanatomical signature identified herein may provide additional, objective information that could influence treatment decisions in adults with ADHD spectrum symptoms.

State-dependent microstructural white matter changes in drug-naïve patients with first-episode psychosis

BACKGROUND

Diffusion tensor imaging (DTI) studies have consistently shown white matter (WM) microstructural abnormalities in schizophrenia. Whether or not such alterations could vary depending on clinical status (i.e. acute psychosis v. remission) remains to be investigated.

METHODS

Twenty-five treatment-naïve first-episode psychosis (FEP) patients and 51 healthy-controls (HC) underwent MRI scanning at baseline. Twenty-one patients were re-scanned as soon as they achieved sustained remission of symptoms; 36 HC were also scanned twice. Rate-of-change maps of longitudinal DTI changes were calculated for in order to examine WM alterations associated with changes in clinical status. We conducted voxelwise analyses of fractional anisotropy (FA) and trace (TR) maps.

RESULTS

At baseline, FEP presented reductions of FA in comparison with HC [p < 0.05, false-discovery rate (FDR)-corrected] affecting fronto-limbic WM and associative, projective and commissural fasciculi. After symptom remission, patients showed FA increase over time (p < 0.001, uncorrected) in some of the above WM tracts, namely the right anterior thalamic radiation, right uncinate fasciculus/inferior fronto-occipital fasciculus, and left inferior fronto-occipital fasciculus/inferior longitudinal fasciculus. We also found significant correlations between reductions in PANSS scores and FA increases over time (p < 0.05, FDR-corrected).

CONCLUSIONS

WM changes affecting brain tracts critical to the integration of perceptual information, cognition and emotions are detectable soon after the onset of FEP and may partially reverse in direct relation to the remission of acute psychotic symptoms. Our findings reinforce the view that WM abnormalities in brain tracts are a key neurobiological feature of acute psychotic disorders, and recovery from such WM pathology can lead to amelioration of symptoms.

Volumetric Analysis from a Harmonized Multisite Brain MRI Study of a Single Subject with Multiple Sclerosis

BACKGROUND AND PURPOSE

MR imaging can be used to measure structural changes in the brains of individuals with multiple sclerosis and is essential for diagnosis, longitudinal monitoring, and therapy evaluation. The North American Imaging in Multiple Sclerosis Cooperative steering committee developed a uniform high-resolution 3T MR imaging protocol relevant to the quantification of cerebral lesions and atrophy and implemented it at 7 sites across the United States. To assess intersite variability in scan data, we imaged a volunteer with relapsing-remitting MS with a scan-rescan at each site.

MATERIALS AND METHODS

All imaging was acquired on Siemens scanners (4 Skyra, 2 Tim Trio, and 1 Verio). Expert segmentations were manually obtained for T1-hypointense and T2 (FLAIR) hyperintense lesions. Several automated lesion-detection and whole-brain, cortical, and deep gray matter volumetric pipelines were applied. Statistical analyses were conducted to assess variability across sites, as well as systematic biases in the volumetric measurements that were site-related.

RESULTS

Systematic biases due to site differences in expert-traced lesion measurements were significant (P < .01 for both T1 and T2 lesion volumes), with site explaining >90% of the variation (range, 13.0-16.4 mL in T1 and 15.9-20.1 mL in T2) in lesion volumes. Site also explained >80% of the variation in most automated volumetric measurements. Output measures clustered according to scanner models, with similar results from the Skyra versus the other 2 units.

CONCLUSIONS

Even in multicenter studies with consistent scanner field strength and manufacturer after protocol harmonization, systematic differences can lead to severe biases in volumetric analyses.

Relationship between APOE Genotype and Structural MRI Measures throughout Adulthood in the Study of Health in Pomerania Population-Based Cohort

BACKGROUND AND PURPOSE

The presence of the apolipoprotein E ε4 allele is the strongest sporadic Alzheimer disease genetic risk factor. We hypothesized that apolipoprotein E ε4 carriers and noncarriers may already differ in imaging patterns in midlife. We therefore sought to identify the effect of apolipoprotein E genotype on brain atrophy across almost the entire adult age span by using advanced MR imaging-based pattern analysis.

MATERIALS AND METHODS

We analyzed MR imaging scans of 1472 participants from the Study of Health in Pomerania (22-90 years of age). We studied the association among age, apolipoprotein E ε4 carrier status, and brain atrophy, which was quantified by using 2 MR imaging-based indices: Spatial Pattern of Atrophy for Recognition of Brain Aging (summarizing age-related brain atrophy) and Spatial Pattern of Abnormality for Recognition of Early Alzheimer Disease (summarizing Alzheimer disease-like brain atrophy patterns), as well as the gray matter volumes in several Alzheimer disease- and apolipoprotein E-related ROIs (lateral frontal, lateral temporal, medial frontal, and hippocampus).

RESULTS

No significant association was found between apolipoprotein E ε4 carrier status and the studied ROIs or the MR imaging-based indices in linear regression models adjusted for age, sex, and education, including an interaction term between apolipoprotein E and age.

CONCLUSIONS

Our study indicates that measurable apolipoprotein E-related brain atrophy does not occur in early adulthood and midlife and suggests that such atrophy may only occur more proximal to the onset of clinical symptoms of dementia.

Working Length Determination of Root Canal of Young Permanent Tooth: An In vitro Study

BACKGROUND

Determination of correct working length is one of the keys to success in endodontic therapy.

AIM

The aim of this study was to evaluate the diagnostic efficacy of various methods to determine working length of root canal.

MATERIALS AND METHODS

Tactile method was assessed using digital radiography and compared with electronic method using apex locator. A total sample of 30 single rooted young permanent teeth the (mandibular first premolars) with matured apices were selected for the study. Access cavity preparation was carried out. Working length was measured by tactile method using digital radiography and electronic method using apex locator with no 15 K file. Actual working length was established by grinding of cementum and dentine from the root apex and was observed under stereomicroscope. Data was collected and statistical analysis was carried out with the help of SPSS-15.

RESULTS

The results of this study showed that there was a significant difference between tactile method assessed by digital radiography and electronic method using apex locator.

CONCLUSION

Apex locator was found to be more reliable and accurate when compared with the actual length.

Schwannoma of the ansa cervicalis

Schwannomas are rare neoplasms that originate from Schwann cells. We present a case report of schwannoma of the ansa cervicalis in a patient where preoperative imaging suggested thyroid pathology. A 25-year-old man presented to the otolaryngology department with a one-year history of an asymptomatic, anterior triangle neck swelling. Imaging and FNA suggested a cystic lesion of the thyroid. However, intraoperatively, the lesion was found between the right sternohyoid and thyrohoid and histology showed findings consistent with a diagnosis of schwannoma, determined to originate from the ansa cervicalis based on its anatomical position. Schwannoma of the ansa cervicalis is extremely rare and there have only been four reported cases in the literature. Schwannomas are often misdiagnosed and confused for other lesions. In our case report we add to the sparse literature on this pathology and highlight common pitfalls in diagnosis and discuss the principles of management of this rare condition.

Navigational systems in rhinology: should we all be using them?

The proximity of the paranasal sinuses to important anatomical structures creates the potential for serious complications following endoscopic sinus surgery. Over recent years, navigational systems have been developed and are increasingly being used by some centres. We summarise the history and principles of navigational sinus surgery, review the medical literature on the topic, and try to assess what role navigational systems should play in modern day rhinology practice.

Post-tonsillectomy morbidity statistics: are they underestimated?

Background:

Post-tonsillectomy morbidity statistics are obtained when patients present to hospital with complications. The two common morbidities are pain and haemorrhage. Hospital-recorded morbidity rates may be an underestimation, as some patients are treated by general practitioners and are therefore not included in hospital audits.

Methods:

Prospective, cohort, questionnaire study to assess: the post-tonsillectomy haemorrhage rate (i.e. actual rate versus hospital recorded rate); and the number of patients with post-operative pain and/or bleeding who were treated with antibiotics by their general practitioner.

Results:

The response rate was 76 per cent (70/92). The actual rate of secondary haemorrhage was three times that noted in the hospital records (15.7 vs 5.7 per cent, respectively). Fifteen patients (21 per cent) required extra analgesia after discharge. General practitioners prescribed antibiotics for pain alone in six patients (11 per cent).

Conclusion:

The actual post-tonsillectomy haemorrhage rate is much higher than that recorded in hospital statistics. General practitioners differ in their treatment of post-tonsillectomy patients presenting with pain alone; some prescribe antibiotics in addition to analgesia.

Grisel syndrome: a delayed presentation in an asymptomatic patient

Grisel syndrome is a rare condition characterised by atlanto-axial subluxation following an inflammatory process in the head and neck region. It occurs more commonly in children and usually presents with cervical pain and torticollis, in addition to symptoms of the primary infection. We present the case of an asymptomatic 78-year-old man who was incidentally found to have atlanto-axial subluxation on a routine follow-up computed tomography scan, three months following successful treatment of a skull base infection. This case emphasises the importance of appropriate follow-up imaging for patients with skull base infections, even if they respond clinically to medical treatment.

A survey of undergraduate otolaryngology experience at Newcastle University Medical School

Introduction: Due to the ‘modernizing medical careers’ changes, doctors with a firm career intention will be able to enter a speciality-specific training programme after their foundation years.

Materials and methods: A questionnaire was emailed to all 204 final year medical students at Newcastle Medical School asking about their ENT undergraduate experience and if they felt it was sufficient to consider a career in otolaryngology.

Results: One hundred and forty-four completed questionnaires (71 per cent) were returned, with respondents giving the following information: 54 per cent had had a formal ENT attachment (average seven and a half days); 24/144 (17 per cent) and 60/144 (42 per cent) respectively had not attended ENT clinic or theatre; less than 50 per cent had seen common ENT operations; 12/144 (8 per cent) had never heard of a septoplasty; two-thirds (24/36) of aspiring general practitioners had never seen a tonsillectomy or grommet insertion; and only 6/30 (20 per cent) of aspiring surgeons felt their ENT experience had been enough to consider the speciality as a career.

Discussion: Alternative methods of delivering an otolaryngology curriculum should be considered. We must promote otolaryngology to medical students at every opportunity.

Observational study of bone-anchored hearing aid infection rates using different post-operative dressings

Introduction: Avoidance of infection at the implant site is a crucial element to the success of bone-anchored hearing aid (BAHA) implantation. However, little evidence exists to suggest the best post-operative wound dressing to use.

Material and methods: We report our experience with 160 consecutive BAHA patients, using four types of post-operative BAHA wound dressing (Tri-adcortyl®, Mepitel®, Allevyn®, and Acticoat 7® with Allevyn). Patients were reviewed at week one and week two post-operatively. Infection was defined as a positive wound swab culture or evidence of cellulitis at the BAHA site.

Results: Post-operative BAHA infection rates were 16 per cent, 50 per cent, 10 per cent and 5 per cent, for each of the four dressings respectively, and the mean number of additional visits to wound care clinic were 1.5, 3.7, one and 0.4, respectively.

Discussion: Acticoat 7 with Allevyn produced the lowest infection rate and thus became the dressing of choice for our BAHA programme.

Obsessive compulsive neurosis: treatment of 28 cases by behaviour therapy

Twenty-eight cases of obsessive compulsive neurosis were treated with a behaviour therapy package and good results were obtained in 15 (53.6%). Relaxation, thought-stopping, implosion, modelling, response prevention, electrical aversion and positive reinforcement wei; the techniques employed. Chronicity, previous treatments, follow-up data, drop-outs and the use of behaviour therapy in our setting are discussed in this paper.

Evaluation of cognitive effects of ect (preliminary observations)

The aim of present double blind controlled study is to evaluate the effects of ECT in Schizophrenia and Depression. 20 depressed and 20 schizophrenic patients of either sex, in the age group 18 to 65 years fulfilling the inclusion and exclusion criteria were taken for study. The psychiatric evaluations were carried out before the treatment, and at the end of 3, 6, 8 and 10 treatments. Cognitive test battery was administered before the treatment and 48 hours after the last treatment. No Post ECT cognitive deficit was observed on the test battery though some patients did complain of forgetfulness subjectively.