LDHB contributes to the regulation of lactate levels and basal insulin secretion in human pancreatic ß cells.

Using 13C6 glucose labeling coupled to gas chromatography-mass spectrometry and 2D 1H-13C heteronuclear single quantum coherence NMR spectroscopy, we have obtained a comparative high-resolution map of glucose fate underpinning ß cell function. In both mouse and human islets, the contribution of glucose to the tricarboxylic acid (TCA) cycle is similar. Pyruvate fueling of the TCA cycle is primarily mediated by the activity of pyruvate dehydrogenase, with lower flux through pyruvate carboxylase. While the conversion of pyruvate to lactate by lactate dehydrogenase (LDH) can be detected in islets of both species, lactate accumulation is 6-fold higher in human islets. Human islets express LDH, with low-moderate LDHA expression and ß cell-specific LDHB expression. LDHB inhibition amplifies LDHA-dependent lactate generation in mouse and human ß cells and increases basal insulin release. Lastly, cis-instrument Mendelian randomization shows that low LDHB expression levels correlate with elevated fasting insulin in humans. Thus, LDHB limits lactate generation in ß cells to maintain appropriate insulin release.

Utility of cortical tissue analysis in normal pressure hydrocephalus.

Clinical improvement following neurosurgical cerebrospinal fluid shunting for presumed idiopathic normal pressure hydrocephalus is variable. Idiopathic normal pressure hydrocephalus patients may have undetected Alzheimer's disease-related cortical pathology that confounds diagnosis and clinical outcomes. In this study, we sought to determine the utility of cortical tissue immuno-analysis in predicting shunting outcomes in idiopathic normal pressure hydrocephalus patients. We performed a pooled analysis using a systematic review as well as analysis of a new, original patient cohort. Of the 2707 screened studies, 3 studies with a total of 229 idiopathic normal pressure hydrocephalus patients were selected for inclusion in this meta-analysis alongside our original cohort. Pooled statistics of shunting outcomes for the 229 idiopathic normal pressure hydrocephalus patients and our new cohort of 36 idiopathic normal pressure hydrocephalus patients revealed that patients with Aß + pathology were significantly more likely to exhibit shunt nonresponsiveness than patients with negative pathology. Idiopathic normal pressure hydrocephalus patients with Alzheimer's disease -related cortical pathology may be at a higher risk of treatment facing unfavorable outcomes following cerebrospinal fluid shunting. Thus, cortical tissue analysis from living patients may be a useful diagnostic and prognostic adjunct for patients with presumed idiopathic normal pressure hydrocephalus and potentially other neurodegenerative conditions affecting the cerebral cortex.

Cases of familial idiopathic normal pressure hydrocephalus implicate genetic factors in disease pathogenesis.

Idiopathic normal pressure hydrocephalus is a disorder of unknown pathophysiology whose diagnosis is paradoxically made by a positive response to its proposed treatment with cerebrospinal fluid diversion. There are currently no idiopathic normal pressure hydrocephalus disease genes or biomarkers. A systematic analysis of familial idiopathic normal pressure hydrocephalus could aid in clinical diagnosis, prognosis, and treatment stratification, and elucidate disease patho-etiology. In this 2-part analysis, we review literature-based evidence for inheritance of idiopathic normal pressure hydrocephalus in 22 pedigrees, and then present a novel case series of 8 familial idiopathic normal pressure hydrocephalus patients. For the case series, demographics, familial history, pre- and post-operative symptoms, and cortical pathology were collected. All novel familial idiopathic normal pressure hydrocephalus patients exhibited improvement following shunt treatment and absence of neurodegenerative cortical pathology (amyloid-beta and hyperphosphorylated tau), in contrast to many sporadic cases of idiopathic normal pressure hydrocephalus with variable clinical responses. Analysis of the 30 total familial idiopathic normal pressure hydrocephalus cases reported herein is highly suggestive of an autosomal dominant mechanism of inheritance. This largest-ever presentation of multiply affected idiopathic normal pressure hydrocephalus pedigrees provides strong evidence for Mendelian inheritance and autosomal dominant transmission of an idiopathic normal pressure hydrocephalus trait in a subset of patients that positively respond to shunting and lack neurodegenerative pathology. Genomic investigation of these families may identify the first bona fide idiopathic normal pressure hydrocephalus disease gene.

Segmentation of cellular ultrastructures on sparsely labeled 3D electron microscopy images using deep learning.

Focused ion beam-scanning electron microscopy (FIB-SEM) images can provide a detailed view of the cellular ultrastructure of tumor cells. A deeper understanding of their organization and interactions can shed light on cancer mechanisms and progression. However, the bottleneck in the analysis is the delineation of the cellular structures to enable quantitative measurements and analysis. We mitigated this limitation using deep learning to segment cells and subcellular ultrastructure in 3D FIB-SEM images of tumor biopsies obtained from patients with metastatic breast and pancreatic cancers. The ultrastructures, such as nuclei, nucleoli, mitochondria, endosomes, and lysosomes, are relatively better defined than their surroundings and can be segmented with high accuracy using a neural network trained with sparse manual labels. Cell segmentation, on the other hand, is much more challenging due to the lack of clear boundaries separating cells in the tissue. We adopted a multi-pronged approach combining detection, boundary propagation, and tracking for cell segmentation. Specifically, a neural network was employed to detect the intracellular space; optical flow was used to propagate cell boundaries across the z-stack from the nearest ground truth image in order to facilitate the separation of individual cells; finally, the filopodium-like protrusions were tracked to the main cells by calculating the intersection over union measure for all regions detected in consecutive images along z-stack and connecting regions with maximum overlap. The proposed cell segmentation methodology resulted in an average Dice score of 0.93. For nuclei, nucleoli, and mitochondria, the segmentation achieved Dice scores of 0.99, 0.98, and 0.86, respectively. The segmentation of FIB-SEM images will enable interpretative rendering and provide quantitative image features to be associated with relevant clinical variables.