TAMI-09. INTRAOPERATIVE MICRODIALYSIS AS A FEASIBLE PLATFORM FOR METABOLIC AND PHARMACODYNAMIC BIOMARKER DISCOVERY

BACKGROUND Progress for gliomas is slowed in part by the paucity of mechanistic feedback during treatment with experimental therapies. Access to extracellular tumor pharmacodynamic biomarkers could provide an avenue to accelerate progress. We have initiated a program of intra-operative microdialysis to accelerate biomarker discovery and to identify candidate outcome measures for translational therapies. METHODS Intraoperative microdialysis was performed with M-dialysis 100kDA catheters and 107 variable rate pumps under an IDE. Four IDH-mutant and two IDH-WT lesions were studied intraoperatively with 3 divergently placed catheters. Microperfusate (artifical CSF+ 3% dextran) was perfused at 2uL/min and collected in 20 min increments. Paired CSF was also obtained when accessible. A parallel cohort of nude mice bearing human IDH-mutant, IDH-WT, or sham intracranial xenografts (n=6-12) underwent intratumoral microdialysis. A pilot murine study of intracranial drug delivery was performed via concurrent microdialysis during convection-enhanced delivery (CED) of saline or the IDH-inhibitor AG120. RESULTS Microdialysate from IDH-mutant intracranial xenografts revealed >100 differentially abundant metabolites compared to sham or IDH-WT tumors, including D2-HG (21x) and MTA(18x), p< 10^-5. The most significantly abundant metabolite was DMA (4x, p< 10^-10). 15-1000uM D2HG was recovered from intra-operative human IDH-mutant tumors and 1-2uM from normal brain adjacent to IDH-WT gliomas and < 1uM in all IDH-WT samples. Forty metabolites differentiated enhancing tumor from adjacent brain in 3/3 paired human samples including upregulated Aminoacyl-tRNA biosynthesis and downregulated purine metabolism. Serial aliquots of microdialysate during saline CED yielded steady D2-HG levels whereas CED with AG120 yielded undetectable D2-HG within 6 hours. CONCLUSION The extracellular metabolic landscape of glioma is diverse, dynamic and reflects tumor biology and response to therapy. Collectively, these studies suggest that intra-tumoral drug testing should be feasible with realistic expectation of gaining metabolic feedback within a short timeframe. Leveraging this paradigm can provide opportunities to accelerate therapeutic translation for gliomas.

Atomic Force Microscope Nanoindentation Analysis of Diffuse Astrocytic Tumor Elasticity: Relation with Tumor Histopathology

This study aims to investigate the influence of isocitrate dehydrogenase gene family (IDH) mutations, World Health Organization (WHO) grade, and mechanical preconditioning on glioma and adjacent brain elasticity through standard monotonic and repetitive atomic force microscope (AFM) nanoindentation. The elastic modulus was measured ex vivo on fresh tissue specimens acquired during craniotomy from the tumor and the peritumoral white matter of 16 diffuse glioma patients. Linear mixed-effects models examined the impact of tumor traits and preconditioning on tissue elasticity. Tissues from IDH-mutant cases were stiffer than those from IDH-wildtype ones among anaplastic astrocytoma patients (p = 0.0496) but of similar elasticity to IDH-wildtype cases for diffuse astrocytoma patients (p = 0.480). The tumor was found to be non-significantly softer than white matter in anaplastic astrocytomas (p = 0.070), but of similar elasticity to adjacent brain in diffuse astrocytomas (p = 0.492) and glioblastomas (p = 0.593). During repetitive indentation, both tumor (p = 0.002) and white matter (p = 0.003) showed initial stiffening followed by softening. Stiffening was fully reversed in white matter (p = 0.942) and partially reversed in tumor (p = 0.015). Tissue elasticity comprises a phenotypic characteristic closely related to glioma histopathology. Heterogeneity between patients should be further explored.

High Grade tumor vs stroke. Utility of PET and MRI corregistration

Sometimes, the clinical presentation of a brain tumour mimics that of stroke or viceversa. In these cases it is useful to evaluate follow-up with MR. The coregistration of PET and MR images improves the diagnostic performance of both techniques. In the area of interest, FDG uptake of any degree, with reference to the adjacent brain tissue uptake, should be considered suggestive of tumor if it corresponds to brain injury in MR, even when the FDG uptake is equal to or lower than that of the normal cerebral cortex. We present a case in which coregistration of images from both techniques contributed to the differential diagnosis of stroke and high-grade glioma, whole-body PET/CT ruled out metastatic etiology, and the results led to surgery.

Individualized diversity in the extracellular metabolome of live human gliomas

Gliomas present a formidable challenge for translational progress. Heterogeneity within and between tumors may demand empirically individualized insights, though relatively little is known about the biochemical milieu within which malignant cells thrive in the in vivo human glioma. We performed a pilot study of intraoperative high molecular weight microdialysis to sample the extracellular tumor environment within three locations in each of five molecularly diverse human gliomas spanning WHO grade 2 oligodendroglioma to WHO grade 4 glioblastoma (GBM). Microdialysates were subjected to targeted (D/L-2-hydroxyglutarate (2-HG)) and untargeted metabolomic analyses, enabling correlation, clustering, fold change, and enrichment analyses. IDH-mutant tumor microdialysate contained markedly higher levels of D2-HG than IDH-wild type tumors. However, IDH status was not predictive of the global metabolomic signature. Rather, two distinct metabolic phenotypes (α and β) emerged, with IDH-WT and IDH-mutant patient samples in each group. Individualized metabolic signatures of enhancing tumor versus adjacent brain were conserved across patients with glioblastoma regardless of metabolic phenotype. Untargeted metabolomic analysis additionally enabled correlative quantification of multiple peri-operatively administered drugs, illustrating regional heterogeneity of blood-brain barrier permeability. As such, acute intraoperative microdialysis affords a previously unharnessed window into individualized heterogeneous microenvironments within and between live human gliomas. Such access to the interstitial milieu of live human gliomas may provide a complementary tool for the development of individualized glioma therapies.

Dynein Light Chain Protein Tctex1: A Novel Prognostic Marker and Molecular Mediator in Glioblastoma

The purpose of this study was to determine the role of Tctex1 (DYNLT1, dynein light chain-1) in the pathophysiology of glioblastoma (GBM). To this end, we performed immunohistochemical analyses on tissues from GBM patients (n = 202). Tctex1 was additionally overexpressed in two different GBM cell lines, which were then evaluated in regard to their proliferative and invasive properties. We found that Tctex1 levels were significantly higher in GBM compared to healthy adjacent brain tissues. Furthermore, high Tctex1 expression was significantly associated with the short overall- (p = 0.002, log-rank) and progression-free (p = 0.028, log-rank) survival of GBM patients and was an independent predictor of poor overall survival in multivariate Cox-regression models. In vitro, Tctex1 promoted the metabolic activity, anchorage-independent growth and proliferation of GBM cells. This phenomenon was previously shown to occur via the phosphorylation of retinoblastoma protein (phospho-RB). Here, we found a direct and significant correlation between the levels of Tctex1 and phospho-RB (Ser807/801) in tissues from GBM patients (p = 0.007, Rho = 0.284, Spearman’s rank). Finally, Tctex1 enhanced the invasiveness of GBM cells and the release of pro-invasive matrix metalloprotease 2 (MMP2). These findings indicate that Tctex1 promotes GBM progression and therefore might be a useful therapeutic target in this type of cancer.

ACOUSTIC SCHWANNOMA WITH INTRATUMORAL HEMORRHAGE –REPORT OF AN UNUSUAL COMPLICATION

Acoustic Schwannoma is a benign neoplasm of the 8th cranial nerve pair, and accounts for 8-10% of all intracranialtumors. Intratumoral haemorrhage is unusual in these tumors and can lead to hydrocephalus or aggravate a preexisting condition. This paper reports a case of acoustic Schwannoma in a child with complication with intratumoral hemorrhage that lead patient to death. Female patient, 9 years old, presented anacusis on the right, sudden, progressing with vomiting, intense headache and vertigo. Magnetic resonance imaging of the skull showed expansive lesion in the cistern of the right cerebellar angle, with content inside the internalauditory canal, with compression of the adjacent brain stem. The diagnostic hypothesis was acoustic Schwannoma. It progressed with worsening of headache, initially controlled with medication and later loss of consciousness. Computed tomography of the skull revealed an expansive lesion in the cistern of the right cerebellar angle with signs of bleeding with extension to the ventricular system. External ventricular shunt was performed, but the patient evolved with several complications, septic shock and death. Intratumoral hemorrhage in the acoustic Schwannoma is a rare event, but its occurrence worsens the clinical picture and may lead to death of the patients due to intracranial hypertension.

MADGAN: unsupervised medical anomaly detection GAN using multiple adjacent brain MRI slice reconstruction

Background Unsupervised learning can discover various unseen abnormalities, relying on large-scale unannotated medical images of healthy subjects. Towards this, unsupervised methods reconstruct a 2D/3D single medical image to detect outliers either in the learned feature space or from high reconstruction loss. However, without considering continuity between multiple adjacent slices, they cannot directly discriminate diseases composed of the accumulation of subtle anatomical anomalies, such as Alzheimer’s disease (AD). Moreover, no study has shown how unsupervised anomaly detection is associated with either disease stages, various (i.e., more than two types of) diseases, or multi-sequence magnetic resonance imaging (MRI) scans. Results We propose unsupervised medical anomaly detection generative adversarial network (MADGAN), a novel two-step method using GAN-based multiple adjacent brain MRI slice reconstruction to detect brain anomalies at different stages on multi-sequence structural MRI: (Reconstruction) Wasserstein loss with Gradient Penalty + 100 $$\ell _1$$ ℓ 1 loss—trained on 3 healthy brain axial MRI slices to reconstruct the next 3 ones—reconstructs unseen healthy/abnormal scans; (Diagnosis) Average $$\ell _2$$ ℓ 2 loss per scan discriminates them, comparing the ground truth/reconstructed slices. For training, we use two different datasets composed of 1133 healthy T1-weighted (T1) and 135 healthy contrast-enhanced T1 (T1c) brain MRI scans for detecting AD and brain metastases/various diseases, respectively. Our self-attention MADGAN can detect AD on T1 scans at a very early stage, mild cognitive impairment (MCI), with area under the curve (AUC) 0.727, and AD at a late stage with AUC 0.894, while detecting brain metastases on T1c scans with AUC 0.921. Conclusions Similar to physicians’ way of performing a diagnosis, using massive healthy training data, our first multiple MRI slice reconstruction approach, MADGAN, can reliably predict the next 3 slices from the previous 3 ones only for unseen healthy images. As the first unsupervised various disease diagnosis, MADGAN can reliably detect the accumulation of subtle anatomical anomalies and hyper-intense enhancing lesions, such as (especially late-stage) AD and brain metastases on multi-sequence MRI scans.

The Brain Is Globally Symmetric: An Analysis of Intra and Interhemispheric Symmetry of Subcortical Structures in the Aging Human Brain

Here we address the hemispheric interdependency of subcortical structures in the aging human brain. In particular, we investigate whether volume variation can be explained with the adjacency of structures in the same hemisphere or is due to the interhemispheric development of mirror subcortical structures in the brain. Seven subcortical structures in both hemispheres were automatically segmented in a large sample of over three 3,312 magnetic resonance imaging (MRI) studies of elderly individuals in their 70s and 80s. We perform Eigenvalue analysis to find that anatomic volumes in the limbic system and basal ganglia show similar statistical dependency when considered in the same hemisphere (intrahemispheric) or in different hemispheres (interhemispheric). Our results indicate that anatomic bilaterality is preserved in the aging human brain, supporting the hypothesis that coupling between non-adjacent brain areas could act as a mechanism to compensate for the deleterious effects of aging.

A Child with Glioblastoma Multiforme — Case Report

Introduction. Glioblastoma multiforme (GBM) is the most common central nervous system (CNS) malignancy. It is characterized by an aggressive course with the presence of rapidly growing cells, infiltrating the adjacent brain tissues. Case Report. The case report concerns a 16-year-old child with glioblastoma multiforme. The paper presents selected care problems observed in the child. Discussion. In caring for a child diagnosed with high-grade glioma, the most important care problems are severe, recurrent headaches, nausea and vomiting due to chemotherapy, chronic stress and anxiety, as well as a significant decrease in mood, resulting in e.g. social isolation. A nurse caring for a child with glioblastoma should not only focus on activities directly related to medical care, but also provide psychological support, which certainly improves the quality of life of the child and his family. Conclusions. A patient with high-grade glioma has many different types of care problems. Some are problems related to the physical sphere, others concern the psychological and social sphere. (JNNN 2020;9(4):152–159) Key Words: care, child, glioblastoma multiforme

Rules of amino acid convergence: Not how many, but who in avian vocal learning clades

Single amino acid variants (SAVs) may provide clues to understanding evolution of traits. A complex trait that has evolved convergently among species is vocal learning, the rare ability to imitate sounds heard and an important component of spoken-language. Here we assessed whether convergent vocal learning bird species have convergent SAVs (CSAVs) that could be associated with their specialized trait. We analyzed avian genomes and identified CSAVs in vocal learners, but also in most species combinations tested. The number of CSAVs among species was proportional to the product of the most recent common ancestor (MRCA; origin) branch lengths of the species in question, and vocal learning birds did not exceed the overall proportion in most test. However, genes with identical CSAVs (iCSAVs) in vocal learning species were uniquely enriched in ‘learning’ functions, and a subset of iCSAV genes were under positive selection and had enriched specialized regulation in vocal learning and their adjacent brain subdivisions. Several top candidate genes converge on the cAMP signaling pathway, including DRD1B and PRKAR2B. Our findings suggest a complex mechanism of amino acid convergences and specialized gene regulation upon which selection acts for specialized convergent traits.