Reversing tozasertib resistance in glioma through inhibition of pyruvate dehydrogenase kinases

Acquired resistance to conventional chemotherapeutic agents limits their effectiveness and can cause cancer treatment to fail. Because enzymes in the aurora kinase family are vital regulators of several mitotic events, we reasoned that targeting these kinases with tozasertib, a pan‐aurora kinase inhibitor, would not only cause cytokinesis defects, but also induce cell death in high‐grade pediatric and adult glioma cell lines. We found that tozasertib induced cell cycle arrest, increased mitochondrial permeability and reactive oxygen species generation, inhibited cell growth and migration, and promoted cellular senescence and pro‐apoptotic activity. However, sustained exposure to tozasertib at clinically relevant concentrations conferred resistance, which led us to examine the mechanistic basis for the emergence of drug resistance. RNA‐sequence analysis revealed a significant upregulation of the gene encoding pyruvate dehydrogenase kinase isoenzyme 4 (PDK4), a pyruvate dehydrogenase (PDH) inhibitory kinase that plays a crucial role in the control of metabolic flexibility under various physiological conditions. Upregulation of PDK1, PDK2, PDK3, or PDK4 protein levels was positively correlated with tozasertib‐induced resistance through inhibition of PDH activity. Tozasertib‐resistant cells exhibited increased mitochondrial mass as measured by 10‐N‐nonyl‐Acridine Orange. Inhibition of PDK with dichloroacetate resulted in increased mitochondrial permeability and cell death in tozasertib‐resistant glioma cell lines. Based on these results, we believe that PDK is a selective target for the tozasertib resistance phenotype and should be considered for further preclinical evaluations.     

Deficits in Behavioral and Neuronal Pattern Separation in Temporal Lobe Epilepsy

In temporal lobe epilepsy, the ability of the dentate gyrus to limit excitatory cortical input to the hippocampus breaks down, leading to seizures. The dentate gyrus is also thought to help discriminate between similar memories by performing pattern separation, but whether epilepsy leads to a breakdown in this neural computation, and thus to mnemonic discrimination impairments, remains unknown. Here we show that temporal lobe epilepsy is characterized by behavioral deficits in mnemonic discrimination tasks, in both humans (females and males) and mice (C57Bl6 males, systemic low-dose kainate model). Using a recently developed assay in brain slices of the same epileptic mice, we reveal a decreased ability of the dentate gyrus to perform certain forms of pattern separation. This is because of a subset of granule cells with abnormal bursting that can develop independently of early EEG abnormalities. Overall, our results linking physiology, computation, and cognition in the same mice advance our understanding of episodic memory mechanisms and their dysfunction in epilepsy.SIGNIFICANCE STATEMENT People with temporal lobe epilepsy (TLE) often have learning and memory impairments, sometimes occurring earlier than the first seizure, but those symptoms and their biological underpinnings are poorly understood. We focused on the dentate gyrus, a brain region that is critical to avoid confusion between similar memories and is anatomically disorganized in TLE. We show that both humans and mice with TLE experience confusion between similar situations. This impairment coincides with a failure of the dentate gyrus to disambiguate similar input signals because of pathologic bursting in a subset of neurons. Our work bridges seizure-oriented and memory-oriented views of the dentate gyrus function, suggests a mechanism for cognitive symptoms in TLE, and supports a long-standing hypothesis of episodic memory theories.     

Functional variability in butyrylcholinesterase activity regulates intrathecal cytokine and astroglial biomarker profiles in patients with Alzheimer's disease

Butyrylcholinesterase (BuChE) activity is associated with activated astrocytes in Alzheimer's disease brain. The BuChE-K variant exhibits 30%–60% reduced acetylcholine (ACh) hydrolyzing capacity. Considering the increasing evidence of an immune–regulatory role of ACh, we investigated if genetic heterogeneity in BuChE affects cerebrospinal fluid (CSF) biomarkers of inflammation and cholinoceptive glial function. Alzheimer's disease patients (n = 179) were BCHE–K-genotyped. Proteomic and enzymatic analyses were performed on CSF and/or plasma. BuChE genotype was linked with differential CSF levels of glial fibrillary acidic protein, S100B, interleukin-1β, and tumor necrosis factor (TNF)-α. BCHE-K noncarriers displayed 100%–150% higher glial fibrillary acidic protein and 64%–110% higher S100B than BCHE-K carriers, who, in contrast, had 40%–80% higher interleukin-1β and 21%–27% higher TNF-α compared with noncarriers. A high level of CSF BuChE enzymatic phenotype also significantly correlated with higher CSF levels of astroglial markers and several factors of the innate complement system, but lower levels of proinflammatory cytokines. These individuals also displayed beneficial paraclinical and clinical findings, such as high cerebral glucose utilization, low β-amyloid load, and less severe progression of clinical symptoms. In vitro analysis on human astrocytes confirmed the involvement of a regulated BuChE status in the astroglial responses to TNF-α and ACh. Histochemical analysis in a rat model of nerve injury-induced neuroinflammation, showed focal assembly of astroglial cells in proximity of BuChE-immunolabeled sites. In conclusion, these results suggest that BuChE enzymatic activity plays an important role in regulating intrinsic inflammation and activity of cholinoceptive glial cells and that this might be of clinical relevance. The dissociation between astroglial markers and inflammatory cytokines indicates that a proper activation and maintenance of astroglial function is a beneficial response, rather than a disease-driving mechanism. Further studies are needed to explore the therapeutic potential of manipulating BuChE activity or astroglial functional status.     

Deletion of the phosphoinositide 3-kinase p110gamma gene attenuates murine atherosclerosis

Inflammatory cell activation by chemokines requires intracellular signaling through phosphoinositide 3-kinase (PI3-kinase) and the PI3-kinase-dependent protein serine/threonine kinase Akt. Atherosclerosis is a chronic inflammatory process driven by oxidatively modified (atherogenic) lipoproteins, chemokines, and other agonists that activate PI3-kinase. Here we show that macrophage PI3-kinase/Akt is activated by oxidized low-density lipoprotein, inflammatory chemokines, and angiotensin II. This activation is markedly reduced or absent in macrophages lacking p110gamma, the catalytic subunit of class Ib PI3-kinase. We further demonstrate activation of macrophage/foam cell PI3-kinase/Akt in atherosclerotic plaques from apolipoprotein E (apoE)-null mice, which manifest an aggressive form of atherosclerosis, whereas activation of PI3-kinase/Akt was undetectable in lesions from apoE-null mice lacking p110gamma despite the presence of class Ia PI3-kinase. Moreover, plaques were significantly smaller in apoE-/-p110gamma-/- mice than in apoE-/-p110gamma+/+ or apoE-/-p110gamma+/-mice at all ages studied. In marked contrast to the embryonic lethality seen in mice lacking class Ia PI3-kinase, germ-line deletion of p110gamma results in mice that exhibit normal viability, longevity, and fertility, with relatively well tolerated defects in innate immune and inflammatory responses that may play a role in diseases such as atherosclerosis and multiple sclerosis. Our results not only shed mechanistic light on inflammatory signaling during atherogenesis, but further identify p110gamma as a possible target for pharmacological intervention in the primary and secondary prevention of human atherosclerotic cardiovascular disease.     

Shared Decision-Making and Patient Empowerment in Preventive Cardiology

Shared decision-making, central to evidence-based medicine and good patient care, begins and ends with the patient. It is the process by which a clinician and a patient jointly make a health decision after discussing options, potential benefits and harms, and considering the patient’s values and preferences. Patient empowerment is crucial to shared decision-making and occurs when a patient accepts responsibility for his or her health. They can then learn to solve their own problems with information and support from professionals. Patient empowerment begins with the provider acknowledging that patients are ultimately in control of their care and aims to increase a patient’s capacity to think critically and make autonomous, informed decisions about their health. This article explores the various components of shared decision-making in scenarios such as hypertension and hyperlipidemia, heart failure, and diabetes. It explores barriers and the potential for improving medication adherence, disease awareness, and self-management of chronic disease.     

Incremental value of live/real time three‐dimensional transthoracic echocardiography over the two‐dimensional technique in assessing carcinoid heart disease involving the aortic valve

We present a case of an adult with metastatic carcinoid heart disease, in whom live/real time three‐dimensional transthoracic echocardiography provided incremental value over two‐dimensional transthoracic echocardiography in assessing involvement of the aortic valve.     

Hyperpigmented Plaques of the Alar Crease: An Unusual Presentation of Acanthosis Nigricans

Although acanthosis nigricans of the posterior neck and intertriginous areas is common, acanthosis nigricans of the supra‐alar creases is rare. We present the case of an obese 16‐year‐old African American boy with hyperpigmented plaques along the supra‐alar creases of his nose. Clinicians should be aware of this rare manifestation, because newly diagnosed acanthosis nigricans should prompt examination for insulin resistance.     

In Vivo Thermal Ablation Monitoring Using Ultrasound Echo Decorrelation Imaging

Previous work indicated that ultrasound echo decorrelation imaging can track and quantify changes in echo signals to predict thermal damage during in vitro radiofrequency ablation (RFA). In the in vivo studies reported here, the feasibility of using echo decorrelation imaging as a treatment monitoring tool was assessed. RFA was performed on normal swine liver (N = 5), and ultrasound ablation using image-ablate arrays was performed on rabbit liver implanted with VX2 tumors (N = 2). Echo decorrelation and integrated backscatter were computed from Hilbert transformed pulse-echo data acquired during RFA and ultrasound ablation treatments. Receiver operating characteristic (ROC) curves were employed to assess the ability of echo decorrelation imaging and integrated backscatter to predict ablation. Area under the ROC curves (AUROC) was determined for RFA and ultrasound ablation using echo decorrelation imaging. Ablation was predicted more accurately using echo decorrelation imaging (AUROC = 0.832 and 0.776 for RFA and ultrasound ablation, respectively) than using integrated backscatter (AUROC = 0.734 and 0.494).