Low-dose biliatresone treatment of pregnant mice causes subclinical biliary disease in their offspring: Evidence for a spectrum of neonatal injury.

Biliary atresia is a neonatal disease characterized by damage, inflammation, and fibrosis of the liver and bile ducts and by abnormal bile metabolism. It likely results from a prenatal environmental exposure that spares the mother and affects the fetus. Our aim was to develop a model of fetal injury by exposing pregnant mice to low-dose biliatresone, a plant toxin implicated in biliary atresia in livestock, and then to determine whether there was a hepatobiliary phenotype in their pups. Pregnant mice were treated orally with 15 mg/kg/d biliatresone for 2 days. Histology of the liver and bile ducts, serum bile acids, and liver immune cells of pups from treated mothers were analyzed at P5 and P21. Pups had no evidence of histological liver or bile duct injury or fibrosis at either timepoint. In addition, growth was normal. However, serum levels of glycocholic acid were elevated at P5, suggesting altered bile metabolism, and the serum bile acid profile became increasingly abnormal through P21, with enhanced glycine conjugation of bile acids. There was also immune cell activation observed in the liver at P21. These results suggest that prenatal exposure to low doses of an environmental toxin can cause subclinical disease including liver inflammation and aberrant bile metabolism even in the absence of histological changes. This finding suggests a wide potential spectrum of disease after fetal biliary injury.

Single-cell NAD(H) levels predict clonal lymphocyte expansion dynamics.

Adaptive immunity requires the expansion of high-affinity lymphocytes from a heterogeneous pool. Whereas current models explain this through signal transduction, we hypothesized that antigen affinity tunes discrete metabolic pathways to license clonal lymphocyte dynamics. Here, we identify nicotinamide adenine dinucleotide (NAD) biosynthesis as a biochemical hub for the T cell receptor affinity-dependent metabolome. Through this central anabolic role, we found that NAD biosynthesis governs a quiescence exit checkpoint, thereby pacing proliferation. Normalizing cellular NAD(H) likewise normalizes proliferation across affinities, and enhancing NAD biosynthesis permits the expansion of lower affinity clones. Furthermore, single-cell differences in NAD(H) could predict division potential for both T and B cells, before the first division, unmixing proliferative heterogeneity. We believe that this supports a broader paradigm in which complex signaling networks converge on metabolic pathways to control single-cell behavior.

Bile acid metabolism mediates cholesterol homeostasis and promotes tumorigenesis in clear cell renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC) incidence has risen steadily over the last decade. Elevated lipid uptake and storage is required for ccRCC cell viability. As stored cholesterol is the most abundant component in ccRCC intracellular lipid droplets, it may also play an important role in ccRCC cellular homeostasis. In support of this hypothesis, ccRCC cells acquire exogenous cholesterol through the HDL receptor SCARB1, inhibition or suppression of which induces apoptosis. Here, we showed that elevated expression of 3 beta-hydroxy steroid dehydrogenase type 7 (HSD3B7), which metabolizes cholesterol-derived oxysterols in the bile acid biosynthetic pathway, is also essential for ccRCC cell survival. Development of an HSD3B7 enzymatic assay and screening for small molecule inhibitors uncovered the compound celastrol as a potent HSD3B7 inhibitor with low micromolar activity. Repressing HSD3B7 expression genetically or treating ccRCC cells with celastrol resulted in toxic oxysterol accumulation, impaired proliferation, and increased apoptosis in vitro and in vivo. These data demonstrate that bile acid synthesis regulates cholesterol homeostasis in ccRCC and identifies HSD3B7 as a plausible therapeutic target.

The Curious Case of Lip Tongue Fusion: A Consequence of Suboptimal Oral Care.

Oral care is an often difficult and an unappreciated part of hospital life. Patients who are unable to provide their own care rely on assistance from hospital personnel. Most sequelae from suboptimal oral care often present over months if not years, in the form of dental caries and periodontal disease. We present an exception, where a 66-year-old patient who experienced widespread ulceration and necrosis from Capnocytophaga-related sepsis received suboptimal oral care, resulting in their tongue being fused to their lip. This was later divided by the oral and maxillofacial team resulting in restoration of full function. Future cases can be avoided in patients with similar symptoms, such as Stevens-Johnson syndrome or erythema multiforme, if rigorous oral care can be provided.

All-Organic Composite Films for High Flexibility and Giant Nonlinear Optical Limiting Responses.

Given the substantial π-electron delocalization observed in 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST), a high third-order nonlinear optical response can be expected that might manifest itself in various ways for potential applications. To probe the possibility and assess its potential, all-organic DAST-polymethyl methacrylate (PMMA) composite films were prepared by a simple solution casting method, and their nonlinear absorption performances were measured by an open-aperture Z-scan system. The results reveal that under irradiation by a 380 fs laser pulse at 520 nm or a 6 ns laser pulse at 532 nm, the DAST-PMMA composite films with a DAST concentration of 0.125 wt % exhibit similar giant optical limiting (OL) responses with OL threshold of 7.84 or 0.37 GW cm-2, both superior to those of most organic and inorganic OL materials measured under similar conditions. These all-organic composite films show high flexibility, and interestingly, their OL responses can remain stable even after exposure to air for 3 months. The superior OL behaviors of such materials in the femtosecond and nanosecond regimes are attributed to the two-photon absorption and the combination of two-photon absorption and excited-state absorption, respectively. The simple preparation, high flexibility, giant OL responses, and excellent environmental stability suggest that such novel all-organic composite films hold great potential for applications in flexible OL devices.

Bcl-xL Enforces a Slow-Cycling State Necessary for Survival in the Nutrient-Deprived Microenvironment of Pancreatic Cancer.

Solid tumors possess heterogeneous metabolic microenvironments where oxygen and nutrient availability are plentiful (fertile regions) or scarce (arid regions). While cancer cells residing in fertile regions proliferate rapidly, most cancer cells in vivo reside in arid regions and exhibit a slow-cycling state that renders them chemoresistant. Here, we developed an in vitro system enabling systematic comparison between these populations via transcriptome analysis, metabolomic profiling, and whole-genome CRISPR screening. Metabolic deprivation led to pronounced transcriptional and metabolic reprogramming, resulting in decreased anabolic activities and distinct vulnerabilities. Reductions in anabolic, energy-consuming activities, particularly cell proliferation, were not simply byproducts of the metabolic challenge, but rather essential adaptations. Mechanistically, Bcl-xL played a central role in the adaptation to nutrient and oxygen deprivation. In this setting, Bcl-xL protected quiescent cells from the lethal effects of cell-cycle entry in the absence of adequate nutrients. Moreover, inhibition of Bcl-xL combined with traditional chemotherapy had a synergistic antitumor effect that targeted cycling cells. Bcl-xL expression was strongly associated with poor patient survival despite being confined to the slow-cycling fraction of human pancreatic cancer cells. These findings provide a rationale for combining traditional cancer therapies that target rapidly cycling cells with those that target quiescent, chemoresistant cells associated with nutrient and oxygen deprivation. SIGNIFICANCE: The majority of pancreatic cancer cells inhabit nutrient- and oxygen-poor tumor regions and require Bcl-xL for their survival, providing a compelling antitumor metabolic strategy.

Quantitative subcellular acyl-CoA analysis reveals distinct nuclear metabolism and isoleucine-dependent histone propionylation.

Quantitative subcellular metabolomic measurements can explain the roles of metabolites in cellular processes but are subject to multiple confounding factors. We developed stable isotope labeling of essential nutrients in cell culture-subcellular fractionation (SILEC-SF), which uses isotope-labeled internal standard controls that are present throughout fractionation and processing to quantify acyl-coenzyme A (acyl-CoA) thioesters in subcellular compartments by liquid chromatography-mass spectrometry. We tested SILEC-SF in a range of sample types and examined the compartmentalized responses to oxygen tension, cellular differentiation, and nutrient availability. Application of SILEC-SF to the challenging analysis of the nuclear compartment revealed a nuclear acyl-CoA profile distinct from that of the cytosol, with notable nuclear enrichment of propionyl-CoA. Using isotope tracing, we identified the branched chain amino acid isoleucine as a major metabolic source of nuclear propionyl-CoA and histone propionylation, thus revealing a new mechanism of crosstalk between metabolism and the epigenome.

Single-Electron Tunneling PbS/InP Heterostructure Nanoplatelets for Synaptic Operations.

Power consumption, thermal management, and wiring challenge of the binary serial architecture drive the search for alternative paradigms to computing. Of special interest is neuromorphic computing, in which materials and device structures are designed to mimic neuronal functionalities with energy-efficient non-linear responses and both short- and long-term plasticities. In this work, we explore and report on the enabling potential of single-electron tunneling (SET) in PbS nanoplatelets epitaxially grown in the liquid phase on InP, which present these key features. By extrapolating the experimental data in the SET regime, we predict and model synaptic operations. The low-energy (

Cholesterol Auxotrophy as a Targetable Vulnerability in Clear Cell Renal Cell Carcinoma.

Clear cell renal cell carcinoma (ccRCC) is characterized by large intracellular lipid droplets containing free and esterified cholesterol; however, the functional significance of cholesterol accumulation in ccRCC cells is unknown. We demonstrate that, surprisingly, genes encoding cholesterol biosynthetic enzymes are repressed in ccRCC, suggesting a dependency on exogenous cholesterol. Mendelian randomization analyses based on 31,000 individuals indicate a causal link between elevated circulating high-density lipoprotein (HDL) cholesterol and ccRCC risk. Depriving ccRCC cells of either cholesterol or HDL compromises proliferation and survival in vitro and tumor growth in vivo; in contrast, elevated dietary cholesterol promotes tumor growth. Scavenger Receptor B1 (SCARB1) is uniquely required for cholesterol import, and inhibiting SCARB1 is sufficient to cause ccRCC cell-cycle arrest, apoptosis, elevated intracellular reactive oxygen species levels, and decreased PI3K/AKT signaling. Collectively, we reveal a cholesterol dependency in ccRCC and implicate SCARB1 as a novel therapeutic target for treating kidney cancer. SIGNIFICANCE: We demonstrate that ccRCC cells are auxotrophic for exogenous cholesterol to maintain PI3K/AKT signaling pathway and ROS homeostasis. Blocking cholesterol import through the HDL transporter SCARB1 compromises ccRCC cell survival and tumor growth, suggesting a novel pharmacologic target for this disease. This article is highlighted in the In This Issue feature, p. 2945.

Porous and nanowire-structured NiO/AgNWs composite electrodes for significantly-enhanced supercapacitive and electrochromic performances.

NiO/AgNWs composite films which specially contain both porous and one-dimensional (1D) nanowire structures are prepared uniformly via a simple chemical bath deposition method. The supercapacitive electrodes constructed by the as-prepared NiO/AgNWs composite films exhibit a high specific capacitance (980 F g-1at 1 A g-1), much higher than that of the pure NiO films. Particularly, a large optical modulation (84.3% at 550 nm) and short switching times for the coloration and bleaching (5.4 and 6.5 s) are also observed if these NiO/AgNWs films serve as the electrochromic materials. The superior capacitive and electrochromic properties of the NiO/AgNWs composite films are attributed to the large electrochemically effective surface areas and enhanced conductivity induced by the addition of 1D AgNWs, which efficiently shorten the ions/electrons diffusion paths and accelerate the reversible redox reactions. Therefore, the NiO/AgNWs composite films hold a great potential for applications as a novel electrode material in supercapacitive and electrochromic devices.

Broadband Terahertz Near-Perfect Absorbers.

Broadband terahertz (THz) absorbers are highly desired in detection, modulation, receiving, and imaging devices. We report the design and successful implementation of a novel broadband THz metasurface with a near-perfect absorption. Different from the traditional metal/dielectric/metal three-layer structures, the as-designed THz absorber has one more metal layer and a dielectric spacer on top, both of which are 200 nm thick. Although the total thickness increased by ∼7%, the near-perfect THz absorption band significantly broadened by 4×, achieving a broadband absorption of 270 GHz. Broadband, polarization-insensitive, and near-perfect THz absorptions were also observed over wide incident angles in these meta-absorbers, where the electric field and power loss were mainly concentrated in the additional thin dielectric layer. Such a broadband THz absorption was achieved through electromagnetic coupling between the top and middle metal layers and the resultant overlapping of the resonance frequencies. This strategy can be adapted to other spectrum-shaping devices.

Metabolic flux analysis and fluxomics-driven determination of reaction free energy using multiple isotopes.

Metabolite concentrations, fluxes, and free energies constitute the basis for understanding and controlling metabolism. Mass spectrometry and stable isotopes are integral tools in quantifying these metabolic features. For absolute metabolite concentration and flux measurement, 13C internal standards and tracers have been the gold standard. In contrast, no established methods exist for comprehensive thermodynamic quantitation under physiological environments. Recently, using high-resolution mass spectrometry and multi-isotope tracing, flux quantitation has been increasingly adopted in broader metabolism. The improved flux quantitation led to determination of Gibbs free energy of reaction (ΔG) in central carbon metabolism using a relationship between reaction reversibility and thermodynamic driving force. Here we highlight recent advances in multi-isotope tracing for metabolic flux and free energy analysis.

A high performance electroformed single-crystallite VO2 threshold switch.

Threshold switches (TSs) are an effective approach for resolving the sneak path problem within a memristor array. VO2 is a promising material for fabricating high-performance TSs. Here we report a single crystal VO2-based TS device with high switching performance. The single crystal monoclinic VO2 channel is obtained by electroforming in a composite vanadium oxide film consisting of VO2, V2O5 and V3O7. The formation mechanism on single crystal VO2 is thoroughly investigated by means of X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The single crystal VO2-based TS device exhibits better switching performance than the polycrystalline monoclinic VO2 counterpart. The TS device based on a single crystal channel with the (2[combining macron]11) orientation exhibits a steep turn-on voltage slope of <0.5 mV dec-1, a fast switching speed of 23 ns, an excellent endurance over 109 cycles, a high Ion/Ioff ratio of 143 and a low sample-to-sample variance. The enhanced switching performance originates from the single crystal feature and specified crystal orientation.

Intermediate bosonic metallic state in the superconductor-insulator transition.

Whether a metallic ground state exists in a two-dimensional system beyond Anderson localization remains an unresolved question. We studied how quantum phase coherence evolves across superconductor-metal-insulator transitions through magnetoconductance quantum oscillations in nanopatterned high-temperature superconducting films. We tuned the degree of phase coherence by varying the etching time of our films. Between the superconducting and insulating regimes, we detected a robust intervening anomalous metallic state characterized by saturating resistance and oscillation amplitude at low temperatures. Our measurements suggest that the anomalous metallic state is bosonic and that the saturation of phase coherence plays a prominent role in its formation.

Salisbury Screen Terahertz Absorber Formed with an Insulator: 4-N,N-Dimethylamino-4'-N'-methyl-stilbazolium Tosylate (DAST).

A novel Salisbury screen absorber (SSA) based on a 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST) crystalline film was designed and fabricated. Different from the conventional SSA, an insulating organic DAST film replaced the normally highly conductive top surface metal layer. The absorption spectra and the structure of this SSA were optimized with a transmission line model to correspond to the DAST absorption peak at 1.1 THz, whose results were further verified by numerical simulations. If the thickness of the DAST film is 4 µm, a nearly perfect terahertz (THz) absorption is possible with this strategy, whereas the absorption of a bare 4 µm thick DAST film would be 4 times lower. The design allows the terahertz response of this DAST system to be tuned by adjusting either the thickness of the DAST film or the spacer, both of which remain in deep sub-wavelength to broaden the range of applications.

Trap-Free Heterostructure of PbS Nanoplatelets on InP(001) by Chemical Epitaxy.

Semiconductor nanocrystalline heterostructures can be produced by the immersion of semiconductor substrates into an aqueous precursor solution, but this approach usually leads to a high density of interfacial traps. In this work, we study the effect of a chemical passivation of the substrate prior to the nanocrystalline growth. PbS nanoplatelets grown on sulfur-treated InP (001) surfaces at temperatures as low as 95 °C exhibit abrupt crystalline interfaces that allow a direct and reproducible electron transfer to the InP substrate through the nanometer-thick nanoplatelets with scanning tunnelling spectroscopy. It is in sharp contrast with the less defined interface and the hysteresis of the current-voltage characteristics found without the passivation step. Based on a tunnelling effect occurring at energies below the bandgap of PbS, we show the formation of a type II, trap-free, epitaxial heterointerface, with a quality comparable to that grown on a nonreactive InP (110) substrate by molecular beam epitaxy. Our scheme offers an attractive alternative to the fabrication of semiconductor heterostructures in the gas phase.

Percolation-amplified infrared sensitivity in titanium oxide-multi-walled carbon nanotube composite films.

Titanium dioxide (TiO2)-multi-walled carbon nanotube (MWCNT) thin films were prepared and studied systematically for the effects of the concentration of MWCNTs on the electro-optical properties. Result shows that the addition of MWCNTs not only improves the optical absorption and electrical conductivity, but also reduces the 1/f noise of the films. Percolation phenomenon is observed at MWCNT concentrations of 0.20-0.25 wt%. In this concentration range, the composite films exhibit an abrupt rise of the temperature coefficient of resistance value (-2.93% K-1) and large general thermal parameter, both of which are desirable for applications in uncooled infrared detectors.

Radiofrequency Ablation vs. Cryoablation for Localized Hepatocellular Carcinoma: A Propensity-matched Population Study.

BACKGROUND/AIM: To compare overall survival (OS) and liver cancer-specific survival (LCSS) of Surveillance, Epidemiology and End Results (SEER) hepatocellular carcinoma (HCC) database patients treated with cryoablation (cryo) or radiofrequency ablation (RFA). MATERIALS AND METHODS: This was a retrospective review of Stage I or II HCC patients from the SEER database treated with cryo and RFA from 2004-2013. Kaplan-Meier and Cox regressions were performed on pooled and propensity-matched cohort. RESULTS: Out of 3,239 patients, RFA showed a significant survival advantage over cryo in liver cancer specific survival (LCSS) (HR=1.634 p=0.0004). A total of 91 propensity-matched pairs had similar OS (HR=1.006 p=0.9768), but no difference in LCSS was observed between the groups [HR=1.412 (95%CI=0.933-2.137) p=0.1023]. Survival Cox models did not reveal treatment type as an independent prognostic factor. CONCLUSION: Propensity-matched cohort showed no significant difference in terms of OS and LCSS was found for patients treated with either cryo or RFA for localized HCC.

Exploring Modifications of an HIV-1 Capsid Inhibitor: Design, Synthesis, and Mechanism of Action.

Recent efforts by both academic and pharmaceutical researchers have focused on the HIV-1 capsid (CA) protein as a new therapeutic target. An interprotomer pocket within the hexamer configuration of the CA, which is also a binding site for key host dependency factors, is the target of the most widely studied CA inhibitor compound PF-3450074 (PF-74). Despite its popularity, PF-74 suffers from properties that limit its usefulness as a lead, most notably it's extremely poor metabolic stability. To minimize unfavorable qualities, we investigated bioisosteric modification of the PF-74 scaffold as a first step in redeveloping this compound. Using a field-based bioisostere identification method, coupled with biochemical and biological assessment, we have created four new compounds that inhibit HIV-1 infection and that bind to the assembled CA hexamer. Detailed mechanism of action studies indicates that the modifications alter the manner in which these new compounds affect HIV-1 capsid core stability, as compared to the parental compound. Further investigations are underway to redevelop these compounds to optimize potency and drug-like characteristics and to deeply define the mechanism of action.

Characterization of diverse homoserine lactone synthases in Escherichia coli.

Quorum sensing networks have been identified in over one hundred bacterial species to date. A subset of these networks regulate group behaviors, such as bioluminescence, virulence, and biofilm formation, by sending and receiving small molecules called homoserine lactones (HSLs). Bioengineers have incorporated quorum sensing pathways into genetic circuits to connect logical operations. However, the development of higher-order genetic circuitry is inhibited by crosstalk, in which one quorum sensing network responds to HSLs produced by a different network. Here, we report the construction and characterization of a library of ten synthases including some that are expected to produce HSLs that are incompatible with the Lux pathway, and therefore show no crosstalk. We demonstrated their function in a common lab chassis, Escherichia coli BL21, and in two contexts, liquid and solid agar cultures, using decoupled Sender and Receiver pathways. We observed weak or strong stimulation of a Lux receiver by longer-chain or shorter-chain HSL-generating Senders, respectively. We also considered the under-investigated risk of unintentional release of incompletely deactivated HSLs in biological waste. We found that HSL-enriched media treated with bleach were still bioactive, while autoclaving deactivates LuxR induction. This work represents the most extensive comparison of quorum signaling synthases to date and greatly expands the bacterial signaling toolkit while recommending practices for disposal based on empirical, quantitative evidence.