Biophysical and structural characterization of the impacts of MET phosphorylation on tepotinib binding.

The receptor tyrosine kinase MET is activated by hepatocyte growth factor binding, followed by phosphorylation of the intracellular kinase domain (KD) mainly within the activation loop (A-loop) on Y1234 and Y1235. Dysregulation of MET can lead to both tumor growth and metastatic progression of cancer cells. Tepotinib is a highly selective, potent type Ib MET inhibitor and approved for treatment of non-small cell lung cancer harboring METex14 skipping alterations. Tepotinib binds to the ATP site of unphosphorylated MET with critical π-stacking contacts to Y1230 of the A-loop, resulting in a high residence time. In our study, we combined protein crystallography, biophysical methods (surface plasmon resonance, differential scanning fluorimetry), and mass spectrometry to clarify the impacts of A-loop conformation on tepotinib binding using different recombinant MET KD protein variants. We solved the first crystal structures of MET mutants Y1235D, Y1234E/1235E, and F1200I in complex with tepotinib. Our biophysical and structural data indicated a linkage between reduced residence times for tepotinib and modulation of A-loop conformation either by mutation (Y1235D), by affecting the overall Y1234/Y1235 phosphorylation status (L1195V and F1200I) or by disturbing critical π-stacking interactions with tepotinib (Y1230C). We corroborated these data with target engagement studies by fluorescence cross-correlation spectroscopy using KD constructs in cell lysates or full-length receptors from solubilized cellular membranes as WT or activated mutants (Y1235D and Y1234E/1235E). Collectively, our results provide further insight into the MET A-loop structural determinants that affect the binding of the selective inhibitor tepotinib.

Welding PROxAb Shuttles: A Modular Approach for Generating Bispecific Antibodies via Site-Specific Protein-Protein Conjugation.

Targeted protein degradation is an innovative therapeutic strategy to selectively eliminate disease-causing proteins. Exemplified by proteolysis-targeting chimeras (PROTACs), they have shown promise in overcoming drug resistance and targeting previously undruggable proteins. However, PROTACs face challenges, such as low oral bioavailability and limited selectivity. The recently published PROxAb Shuttle technology offers a solution enabling the targeted delivery of PROTACs using antibodies fused with PROTAC-binding domains derived from camelid single-domain antibodies (VHHs). Here, a modular approach to quickly generate PROxAb Shuttles by enzymatically coupling PROTAC-binding VHHs to off-the-shelf antibodies was developed. The resulting conjugates retained their target binding and internalization properties, and incubation with BRD4-targeting PROTACs resulted in formation of defined PROxAb-PROTAC complexes. These complexes selectively induced degradation of the BRD4 protein, resulting in cytotoxicity specifically to cells expressing the antibody's target. The chemoenzymatic approach described herein provides a versatile and efficient solution for generating antibody-VHH conjugates for targeted protein degradation applications, but it could also be used to combine antibodies and VHH binders to generate bispecific antibodies for further applications.

Protection from UV light is an evolutionarily conserved feature of the haematopoietic niche.

Haematopoietic stem and progenitor cells (HSPCs) require a specific microenvironment, the haematopoietic niche, which regulates HSPC behaviour1,2. The location of this niche varies across species, but the evolutionary pressures that drive HSPCs to different microenvironments remain unknown. The niche is located in the bone marrow in adult mammals, whereas it is found in other locations in non-mammalian vertebrates, for example, in the kidney marrow in teleost fish. Here we show that a melanocyte umbrella above the kidney marrow protects HSPCs against ultraviolet light in zebrafish. Because mutants that lack melanocytes have normal steady-state haematopoiesis under standard laboratory conditions, we hypothesized that melanocytes above the stem cell niche protect HSPCs against ultraviolet-light-induced DNA damage. Indeed, after ultraviolet-light irradiation, unpigmented larvae show higher levels of DNA damage in HSPCs, as indicated by staining of cyclobutane pyrimidine dimers and have reduced numbers of HSPCs, as shown by cmyb (also known as myb) expression. The umbrella of melanocytes associated with the haematopoietic niche is highly evolutionarily conserved in aquatic animals, including the sea lamprey, a basal vertebrate. During the transition from an aquatic to a terrestrial environment, HSPCs relocated into the bone marrow, which is protected from ultraviolet light by the cortical bone around the marrow. Our studies reveal that melanocytes above the haematopoietic niche protect HSPCs from ultraviolet-light-induced DNA damage in aquatic vertebrates and suggest that during the transition to terrestrial life, ultraviolet light was an evolutionary pressure affecting the location of the haematopoietic niche.

Differences in Sustained Cellular Effects of MET inhibitors Are Driven by Prolonged Target Engagement and Lysosomal Retention.

Intracellular distribution of drug compounds is dependent on physicochemical characteristics and may have a significant bearing on the extent of target occupancy and, ultimately, drug efficacy. We assessed differences in the physicochemical profiles of MET inhibitors capmatinib, crizotinib, savolitinib, and tepotinib and their effects on cell viability and MET phosphorylation under steady-state and washout conditions (to mimic an open organic system) in a human lung cancer cell line. To examine the differences of the underlying molecular mechanisms at the receptor level, we investigated the residence time at the kinase domain and the cellular target engagement. We found that the ranking of the drugs for cell viability was different under steady-state and washout conditions and that under washout conditions, tepotinib displayed the most potent inhibition of phosphorylated MET. Postwashout effects were correlated with the partitioning of the drug into acidic subcellular compartments such as lysosomes, and the tested MET inhibitors were grouped according to their ability to access lysosomes (crizotinib and tepotinib) or not (capmatinib and savolitinib). Reversible lysosomal retention may represent a valuable intracellular storage mechanism for MET inhibitors, enabling prolonged receptor occupancy in dynamic, open-physiologic systems and may act as a local drug reservoir. The use of washout conditions to simulate open systems and investigate intracellular drug distribution is a useful characterization step that deserves further investigation. SIGNIFICANCE STATEMENT: Generally, determination of potency and receptor occupancy is performed under steady-state conditions. In vivo conditions are more complex due to concentration differences between compartments and equilibrium processes. Experiments under steady state cannot explore effects such as sustained target inhibition. This study has shown that differences between MET inhibitors are observable by applying washout conditions to in vitro assays. This important finding applies to most compound classes and may inspire readers to rethink their assay designs in the future.

Diffusion MRI in Peripheral Nerves: Optimized b Values and the Role of Non-Gaussian Diffusion.

Background Diffusion-weighted imaging (DWI) provides specific in vivo information about tissue microstructure, which is increasingly recognized for various applications outside the central nervous system. However, standard sequence parameters are commonly adopted from optimized central nervous system protocols, thus potentially neglecting differences in tissue-specific diffusional behavior. Purpose To characterize the optimal tissue-specific diffusion imaging weighting scheme over the b domain in peripheral nerves under physiologic and pathologic conditions. Materials and Methods In this prospective cross-sectional study, 3-T MR neurography of the sciatic nerve was performed in healthy volunteers (n = 16) and participants with type 2 diabetes (n = 12). For DWI, 16 b values in the range of 0-1500 sec/mm2 were acquired in axial and radial diffusion directions of the nerve. With a region of interest-based approach, diffusion-weighted signal behavior as a function of b was estimated using standard monoexponential, biexponential, and kurtosis fitting. Goodness of fit was assessed to determine the optimal b value for two-point DWI/diffusion tensor imaging (DTI). Results Non-Gaussian diffusional behavior was observed beyond b values of 600 sec/mm2 in the axial and 800 sec/mm2 in the radial diffusion direction in both participants with diabetes and healthy volunteers. Accordingly, the biexponential and kurtosis models achieved a better curve fit compared with the standard monoexponential model (Akaike information criterion >99.9% in all models), but the kurtosis model was preferred in the majority of cases. Significant differences between healthy volunteers and participants with diabetes were found in the kurtosis-derived parameters Dk and K. The results suggest an upper bound b value of approximately 700 sec/mm2 for optimal standard DWI/DTI in peripheral nerve applications. Conclusion In MR neurography, an ideal standard diffusion-weighted imaging/diffusion tensor imaging protocol with b = 700 sec/mm2 is suggested. This is substantially lower than in the central nervous system due to early-occurring non-Gaussian diffusion behavior and emphasizes the need for tissue-specific b value optimization. Including higher b values, kurtosis-derived parameters may represent promising novel imaging markers of peripheral nerve disease. ©RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Jang and Du in this issue.

Evaluation of MR-neurography in diagnosis and treatment in peripheral nerve surgery of the upper extremity: A matched cohort study.

INTRODUCTION: "Watch and wait"-strategies from 3 to 6 months for peripheral nerve injuries are standard of care in specialized centers. However, this contradiction between delayed decision-making and the demand for fast reinnervation, especially of the motoric endplate, has not yet been overcome. Therefore, this study aimed to investigate the time-sparing effects by accelerated decision-making due to the complementary MR-neurography application combined with established diagnostics like electroneurography and neurosonography from the first admission to the determination of the treatment plan. PATIENTS AND METHODS: A retrospective matched-pair chart review analysis with Supplementary MR-neurography in the period between 2014 and 2017 was designed. Matching was performed by the parameters of nerve type, localization of the nerve injury, patient age, and treatment of the injury. Twenty-nine patients were included and matched in the study. MR-neurography imaging was performed by a 3T magnetic resonance imaging with a sampling perfection with application optimized contrasts using different flip angle evolution short tau inversion recovery sequence for the brachial plexus and gradient echo accurate fast imaging with steady-state free precession sequence for the upper extremity. Time to decision-making was investigated for or against a surgical intervention for patients with or without a Supplementary MR-neurography. RESULTS: In general, MR-neurography accelerated decision-making for 28 days, with results of 37.5 + 5.4 days with Supplementary MR-neurography and 65.3 + 9.7 days without Supplementary MR-neurography (p = .05). Within the first 90 days following trauma, patients with MR-neurography (38.2 ± 7.7 days) benefit under a significant faster decision-making (p = .05) than patients without MR-neurography (79.0 + 14.2 days). After 90 days, no evidence of accelerated decision-making was found with the addition of MR-neurography (p = .6). In 10 of the 29 patients, despite additional electroneurography and neurosonography, no decision could be made and the MR-neurography has been used primarily as a diagnostic tool. CONCLUSION: MR-neurography has significant time-sparing effects on the decision-making for approximately 4 weeks within the first 90 days after the trauma. This may help overcome the paradigm of "watch and wait"-strategies during the first 3-6 months after the peripheral nerve injury.

GCA: Better ✓check for third cranial nerve involvement!

KEY POINTS: • The intriguing "Check Mark Sign" suggests 3rd cranial nerve involvement in GCA.

Reliability and reproducibility of sciatic nerve magnetization transfer imaging and T2 relaxometry.

OBJECTIVES: To assess the interreader and test-retest reliability of magnetization transfer imaging (MTI) and T2 relaxometry in sciatic nerve MR neurography (MRN). MATERIALS AND METHODS: In this prospective study, 21 healthy volunteers were examined three times on separate days by a standardized MRN protocol at 3 Tesla, consisting of an MTI sequence, a multi-echo T2 relaxometry sequence, and a high-resolution T2-weighted sequence. Magnetization transfer ratio (MTR), T2 relaxation time, and proton spin density (PSD) of the sciatic nerve were assessed by two independent observers, and both interreader and test-retest reliability for all readout parameters were reported by intraclass correlation coefficients (ICCs) and standard error of measurement (SEM). RESULTS: For the sciatic nerve, overall mean ± standard deviation MTR was 26.75 ± 3.5%, T2 was 64.54 ± 8.2 ms, and PSD was 340.93 ± 78.8. ICCs ranged between 0.81 (MTR) and 0.94 (PSD) for interreader reliability and between 0.75 (MTR) and 0.94 (PSD) for test-retest reliability. SEM for interreader reliability was 1.7% for MTR, 2.67 ms for T2, and 21.3 for PSD. SEM for test-retest reliability was 1.7% for MTR, 2.66 ms for T2, and 20.1 for PSD. CONCLUSIONS: MTI and T2 relaxometry of the sciatic nerve are reliable and reproducible. The values of measurement imprecision reported here may serve as a guide for correct interpretation of quantitative MRN biomarkers in future studies. KEY POINTS: • Magnetization transfer imaging (MTI) and T2 relaxometry of the sciatic nerve are reliable and reproducible. • The imprecision that is unavoidably associated with different scans or different readers can be estimated by the here presented SEM values for the biomarkers T2, PSD, and MTR. • These values may serve as a guide for correct interpretation of quantitative MRN biomarkers in future studies and possible clinical applications.

Inhibitors of heat shock protein 70 (Hsp70) with enhanced metabolic stability reduce tau levels.

The molecular chaperone, Heat Shock Protein 70 (Hsp70), is an emerging drug target for neurodegenerative diseases, because of its ability to promote degradation of microtubule-associated protein tau (MAPT/tau). Recently, we reported YM-08 as a brain penetrant, allosteric Hsp70 inhibitor, which reduces tau levels. However, the benzothiazole moiety of YM-08 is vulnerable to metabolism by CYP3A4, limiting its further application as a chemical probe. In this manuscript, we designed and synthesized seventeen YM-08 derivatives by systematically introducing halogen atoms to the benzothiazole ring and shifting the position of the heteroatom in a distal pyridine. In microsome assays, we found that compound JG-23 has 12-fold better metabolic stability and it retained the ability to reduce tau levels in two cell-based models. These chemical probes of Hsp70 are expected to be useful tools for studying tau homeostasis.

Dynamics of somatic cell count (SCC) and differential SCC during and following intramammary infections.

Somatic cell count is frequently used as an indicator of intramammary infections (IMI) in dairy cattle worldwide. The newly introduced differential SCC (DSCC) can potentially contribute to detection of IMI. The purpose of this study was to investigate the dynamics of SCC and DSCC after IMI. We used a data set with monthly samples from 2 Danish dairy herds through 1 yr, using bacterial culture to identify IMI. The dynamics of SCC and DSCC with regard to IMI were assessed at quarter level following new IMI with each of 3 defined pathogen groups, major, minor, or "other" pathogens, using general additive models. Both SCC and DSCC increased after IMI, with a more pronounced increase if major or other pathogens were detected compared with minor pathogens. We found that DSCC increased after IMI with other pathogens in both herds and, in herd 2, after IMI caused by major and minor pathogens. We also estimated the duration of increased SCC and DSCC when they exceeded a threshold, done separately for each pathogen group. Major pathogens had the longest-lasting effect in both herds for both SCC and DSCC. We conclude that the magnitude and duration of response of SCC and DSCC to IMI differs between herds and causative pathogens.

Isomorphic diffuse glioma is a morphologically and molecularly distinct tumour entity with recurrent gene fusions of MYBL1 or MYB and a benign disease course.

The "isomorphic subtype of diffuse astrocytoma" was identified histologically in 2004 as a supratentorial, highly differentiated glioma with low cellularity, low proliferation and focal diffuse brain infiltration. Patients typically had seizures since childhood and all were operated on as adults. To define the position of these lesions among brain tumours, we histologically, molecularly and clinically analysed 26 histologically prototypical isomorphic diffuse gliomas. Immunohistochemically, they were GFAP-positive, MAP2-, OLIG2- and CD34-negative, nuclear ATRX-expression was retained and proliferation was low. All 24 cases sequenced were IDH-wildtype. In cluster analyses of DNA methylation data, isomorphic diffuse gliomas formed a group clearly distinct from other glial/glio-neuronal brain tumours and normal hemispheric tissue, most closely related to paediatric MYB/MYBL1-altered diffuse astrocytomas and angiocentric gliomas. Half of the isomorphic diffuse gliomas had copy number alterations of MYBL1 or MYB (13/25, 52%). Gene fusions of MYBL1 or MYB with various gene partners were identified in 11/22 (50%) and were associated with an increased RNA-expression of the respective MYB-family gene. Integrating copy number alterations and available RNA sequencing data, 20/26 (77%) of isomorphic diffuse gliomas demonstrated MYBL1 (54%) or MYB (23%) alterations. Clinically, 89% of patients were seizure-free after surgery and all had a good outcome. In summary, we here define a distinct benign tumour class belonging to the family of MYB/MYBL1-altered gliomas. Isomorphic diffuse glioma occurs both in children and adults, has a concise morphology, frequent MYBL1 and MYB alterations and a specific DNA methylation profile. As an exclusively histological diagnosis may be very challenging and as paediatric MYB/MYBL1-altered diffuse astrocytomas may have the same gene fusions, we consider DNA methylation profiling very helpful for their identification.

Ontogenetic plasticity in cranial morphology is associated with a change in the food processing behavior in Alpine newts.

BACKGROUND: The feeding apparatus of salamanders consists mainly of the cranium, mandible, teeth, hyobranchial apparatus and the muscles of the cranial region. The morphology of the feeding apparatus in turn determines the boundary conditions for possible food processing (i.e., intraoral mechanical reduction) mechanisms. However, the morphology of the feeding apparatus changes substantially during metamorphosis, prompting the hypothesis that larvae might use a different food processing mechanism than post-metamorphic adults. Salamandrid newts with facultative metamorphosis are suitable for testing this hypothesis as adults with divergent feeding apparatus morphologies often coexist in the same population, share similar body sizes, and feed on overlapping prey spectra. METHODS: We use high-speed videography to quantify the in vivo movements of key anatomical elements during food processing in paedomorphic and metamorphic Alpine newts (Ichthyosaura alpestris). Additionally, we use micro-computed tomography (µCT) to analyze morphological differences in the feeding apparatus of paedomorphic and metamorphic Alpine newts and sort them into late-larval, mid-metamorphic and post-metamorphic morphotypes. RESULTS: Late-larval, mid-metamorphic and post-metamorphic individuals exhibited clear morphological differences in their feeding apparatus. Regardless of the paedomorphic state being externally evident, paedomorphic specimens can conceal different morphotypes (i.e., late-larval and mid-metamorphic morphotypes). Though feeding on the same prey under the same (aquatic) condition, food processing kinematics differed between late-larval, mid-metamorphic and post-metamorphic morphotypes. CONCLUSIONS: The food processing mechanism in the Alpine newt changes along with morphology of the feeding apparatus during ontogeny, from a mandible-based to a tongue-based processing mechanism as the changing morphology of the mandible prevents chewing and the tongue allows enhanced protraction. These results could indicate that early tetrapods, in analogy to salamanders, may have developed new feeding mechanisms in their aquatic environment and that these functional innovations may have later paved the way for terrestrial feeding mechanisms.

Flexibility of intraoral food processing in the salamandrid newt Triturus carnifex: effects of environment and prey type.

Intraoral food processing mechanisms are known for all major vertebrate groups, but the form and function of systems used to crush, grind or puncture food items can differ substantially between and within groups. Most vertebrates display flexible mechanisms of intraoral food processing with respect to different environmental conditions or food types. It has recently been shown that newts use cyclical loop-motions of the tongue to rasp prey against the palatal dentition. However, it remains unknown whether newts can adjust their food processing behavior in response to different food types or environmental conditions. Newts are interesting models for studying the functional adaptation to different conditions because of their unique and flexible lifestyle: they seasonally change between aquatic and terrestrial habitats, adapt their prey-capture mode to the respective environment, and consume diverse food types with different mechanical properties. Using X-ray high-speed recordings, anatomical investigations, behavioral analyses and mechanical property measurements, we tested the effects of the medium in which feeding occurs (water/air) and the food type (maggot, earthworm, cricket) on the processing behavior in Triturus carnifex We discovered that food processing, by contrast to prey capture, differed only slightly between aquatic and terrestrial habitats. However, newts adjusted the number of processing cycles to different prey types: while maggots were processed extensively, earthworm pieces were barely processed at all. We conclude that, in addition to food mechanical properties, sensory feedback such as smell and taste appear to induce flexible processing responses, while the medium in which feeding occurs appears to have less of an effect.

A salamander that chews using complex, three-dimensional mandible movements.

Most non-mammal tetrapods have a hinge-like jaw operation restricted to vertical opening and closing movements. Many mammal jaw joints, by contrast, operate in more complex, three-dimensional (3D) ways, involving not only vertical but also propalinal (rostro-caudal) and transverse (lateral) movements. Data on intraoral food processing in lissamphibians and sauropsids has prompted a generally accepted view that these groups mostly swallow food unreduced, and that in those cases where lissamphibians and sauropsids chew, they mostly use simple vertical jaw movements for food processing. The exception to this generally accepted view is the occurrence of some propalinal chewing in sauropsids. We combined 3D kinematics and morphological analyses from biplanar high-speed video fluoroscopy and micro-computed tomography to determine how the paedomorphic salamander Siren intermedia treats captured food. We discovered not only that S. intermedia uses intraoral food processing but also that the elaborated morphology of its jaw joint facilitates mandibular motions in all three planes, resulting in complex 3D chewing. Thus, our data challenge the commonly held view that complex 3D chewing movements are exclusive to mammals, by suggesting that such mechanisms might have evolved early in the tetrapod evolution.

Quantitative Association of Anatomical and Functional Classes of Olfactory Bulb Neurons.

Juxtaglomerular cells (JGCs) of the olfactory bulb (OB) glomerular layer (GL) play a fundamental role in olfactory information processing. Their variability in morphology, physiology, and connectivity suggests distinct functions. The quantitative understanding of population-wise morphological and physiological properties and a comprehensive classification based on quantitative parameters, however, is still lacking, impeding the analysis of microcircuits. Here, we provide multivariate clustering of 95 in vitro sampled cells from the GL of the mouse (male or female C57BL/6) OB and perform detailed morphological and physiological characterization for the seven computed JGC types. Using a classifier based on a subselection of parameters, we identified the neuron types in paired recordings to characterize their functional connectivity. We found that 4 of the 7 clusters comply with prevailing concepts of GL cell types, whereas the other 3 represent own distinct entities. We have labeled these entities horizontal superficial tufted cell (hSTC), vertical superficial tufted cell, and microglomerular cell (MGC): The hSTC is a tufted cell with a lateral dendrite that much like mitral cells and tufted cells receives excitatory inputs from the external tufted cell but likewise serves as an excitatory element for glomerular interneurons. The vertical superficial tufted cell, on the other hand, represents a tufted cell type with vertically projecting basal dendrites. We further define the MGC, characterized by a small dendritic tree and plateau action potentials. In addition to olfactory nerve-driven and external tufted cell driven interneurons, these MGCs represent a third functionally distinct type, the hSTC-driven interneurons. The presented correlative analysis helps to bridge the gap between branching patterns and cellular functional properties, permitting the integration of results from in vivo recordings, advanced morphological tools, and connectomics.SIGNIFICANCE STATEMENT The variance of neuron properties is a feature across mammalian cerebral circuits, contributing to signal processing and adding computational robustness to the networks. It is particularly noticeable in the glomerular layer of the olfactory bulb, the first site of olfactory information processing. We provide the first unbiased population-wise multivariate analysis to correlate morphological and physiological parameters of juxtaglomerular cells. We identify seven cell types, including four previously described neuron types, and identify further three distinct classes. The presented correlative analysis of morphological and physiological parameters gives an opportunity to predict morphological classes from physiological measurements or the functional properties of neurons from morphology and opens the way to integrate results from in vivo recordings, advanced morphological tools, and connectomics.

Amyotrophic Lateral Sclerosis versus Multifocal Motor Neuropathy: Utility of MR Neurography.

Background Differential diagnosis between amyotrophic lateral sclerosis (ALS) and multifocal motor neuropathy (MMN) relies on clinical examination and electrophysiological criteria. Peripheral nerve imaging might assist this differential diagnosis. Purpose To assess diagnostic accuracy of MR neurography in the differential diagnosis of ALS and MMN. Materials and Methods This prospective study was conducted between December 2015 and April 2017. Study participants with ALS or MMN underwent MR neurography of the lumbosacral plexus, midthigh, proximal calf, and midupper arm of the clinically more affected side using high-resolution T2-weighted sequences. Matched healthy study participants who underwent MR neurography served as a control group. Two blinded readers independently rated fascicular lesions and muscle denervation signs on a five-point scale and made an image-only diagnosis, which was compared with the clinical diagnosis to assess diagnostic accuracy (reported for ALS vs non-ALS and MMN vs non-MMN). The Kruskal-Wallis test was used to compare readers' scoring results. Results Twenty-two participants with ALS (12 men and 10 women; mean age ± standard deviation, 62.3 years ± 9.0), eight participants with MMN (seven men and one woman; mean age, 57.6 years ± 18.6), and 15 healthy participants (seven men and eight women; mean age, 59.1 years ± 10.9) were enrolled in this study. Nerves of participants with ALS either appeared normal or showed T2-weighted hyperintensities without fascicular enlargement (reader 1, 22 of 22 participants; reader 2, 21 of 22 participants). In contrast, nerves in MMN were characterized by fascicular swellings (reader 1, six of eight participants; reader 2, seven of eight participants). Muscle denervation signs were more prominent in ALS than in MMN. Inter-rater reliability for blinded diagnosis was κ of 0.82. By consensus, the sensitivity to diagnose ALS (vs MMN and healthy control participants) was 19 of 22 (86% [95% confidence interval {CI}: 67%, 95%]). The corresponding specificity was 23 of 23 (100% [95% CI: 86%, 100%]). The sensitivity to diagnose MMN (vs ALS and healthy control participants) was seven of eight (88% [95% CI: 53%, 99%]). The corresponding specificity was 37 of 37 (100% [95% CI: 91%, 100%]). Conclusion MR neurography is an accurate method for assisting in the differential diagnosis of amyotrophic lateral sclerosis and multifocal motor neuropathy. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Andreisek in this issue.

Dorsal root ganglia volume differentiates schwannomatosis and neurofibromatosis 2.

Schwannomatosis and neurofibromatosis type 2 are hereditary tumor syndromes, and peripheral neuropathy has been reported in both. We prospectively applied in vivo morphometric measurement of dorsal root ganglia volume in 16 schwannomatosis patients, 14 neurofibromatosis type 2 patients, and 26 healthy controls by magnetic resonance neurography. Compared to healthy controls, dorsal root ganglia hypertrophy was a consistent finding in neurofibromatosis type 2 (L3, + 267%; L4, + 235%; L5, + 241%; S1, + 300%; S2, + 242%; Bonferroni-adjusted p < 0.001) but not in schwannomatosis. Dorsal root ganglia may be a vulnerable site in origination of areflexia and sensory loss and a useful diagnostic marker in neurofibromatosis type 2. Ann Neurol 2018;83:854-857.

Susceptibility-weighted imaging in malignant melanoma brain metastasis.

BACKGROUND: The value of cerebral susceptibility-weighted imaging (SWI) in malignant melanoma (MM) patients remains controversial and the effect of melanin on SWI is not well understood. PURPOSE: To systematically analyze the spectrum of intracerebral findings in MM brain metastases (BM) on SWI and to determine the diagnostic value of SWI. STUDY TYPE: Retrospective. POPULATION/SUBJECTS: In all, 100 patients with melanoma BM (69 having received radiotherapy [RT] and 31 RT-naïve) and a control group of 100 melanoma patients without BM were included. For detailed analysis of signal characteristics, 175 metastases were studied. FIELD STRENGTH/SEQUENCE: Gradient echo SWI sequence at 1.5, 3.0, and 9.4 T. ASSESSMENT: Signal characteristics from melanotic and amelanotic BMs on SWI with a focus on blooming artifacts were analyzed, as well as the presence and longitudinal dynamics of isolated SWI blooming artifacts in patients with and without BM. STATISTICAL TESTS: Chi-squared and Student's t-test were used for contingency table measures and group data of signal and clinical characteristics, respectively. RESULTS: Melanotic and amelanotic metastases did not show significant differences of SWI blooming artifacts (38% vs. 43%, P = 0.61). Most metastases without an initial SWI artifact developed a signal dropout during follow-up (80%; 65/81). Isolated SWI artifacts were detected more frequently in patients with BM (20 vs. 9, P = 0.03), of which the majority were found in patients who had received RT (17 vs. 3, P = 0.08). None of these isolated SWI blooming artifacts turned into overt metastases over time (median follow-up: 8.5 months). Similar findings persisted as remnants of successfully treated metastases (88%; 7/8). DATA CONCLUSION: We conclude that SWI provides little additional diagnostic benefit over standard T1 -weighted imaging, as melanin content alone does not cause diagnostically relevant SWI blooming. Signal transition of SWI may rather indicate secondary phenomena like microbleeding and/or metal scavenging. Our results suggest that isolated SWI artifacts do not constitute vital tumor tissue but represent unspecific microbleedings, RT-related parenchymal changes or posttherapeutic remnants of former metastatic lesions. LEVEL OF EVIDENCE: 3 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2019;50:1251-1259.

Brain Morphometry Methods for Feature Extraction in Random Subspace Ensemble Neural Network Classification of First-Episode Schizophrenia.

Machine learning (ML) is a growing field that provides tools for automatic pattern recognition. The neuroimaging community currently tries to take advantage of ML in order to develop an auxiliary diagnostic tool for schizophrenia diagnostics. In this letter, we present a classification framework based on features extracted from magnetic resonance imaging (MRI) data using two automatic whole-brain morphometry methods: voxel-based (VBM) and deformation-based morphometry (DBM). The framework employs a random subspace ensemble-based artificial neural network classifier-in particular, a multilayer perceptron (MLP). The framework was tested on data from first-episode schizophrenia patients and healthy controls. The experiments differed in terms of feature extraction methods, using VBM, DBM, and a combination of both morphometry methods. Thus, features of different types were available for model adaptation. As we expected, the combination of features increased the MLP classification accuracy up to 73.12%-an improvement of 5% versus MLP-based only on VBM or DBM features. To further verify the findings, other comparisons using support vector machines in place of MLPs were made within the framework. However, it cannot be concluded that any classifier was better than another.

Chewing or not? Intraoral food processing in a salamandrid newt.

Food processing refers to any form of mechanical breakdown of food prior to swallowing. Variations of this behaviour are found within all major gnathostome groups. Chewing is by far the most commonly used intraoral processing mechanism and involves rhythmic mandibular jaw and hyobranchial (tongue) movements. Chewing occurs in chondrichthyans (sharks and rays), actinopterygians (ray-finned fishes), dipnoi (lungfishes) as well as amniotes and involves similarities in the patterns of muscle activity and movement of the feeding apparatus. It has been suggested that amniote chewing, which involves the interaction of movements of the mandibular jaw and the muscular tongue, has evolved as part of the tetrapod land invasion. However, little is known about food-processing mechanisms in lissamphibians, which might have retained many ancestral tetrapod features. Here, we identified a processing mechanism in the salamandrid newt, Triturus carnifex, which after prey capture displays cyclic head bobbing in concert with rhythmic jaw and tongue movements. We used high-speed fluoroscopy, anatomical reconstructions and analyses of stomach contents to show that newts, although not using their mandibular jaws, deploy a derived processing mechanism where prey items are rasped rhythmically against the dentition on the mouth roof, driven by a loop motion of the tongue. We then compared patterns and coordination of jaw and tongue movements across gnathostomes to conclude that food processing in this newt species shares traits with processing mechanisms in fish as well as amniotes. This discovery casts salamanders as promising models for reconstructing the evolution of intraoral processing mechanisms at the fish-tetrapod split.