Airfares fluctuate due to demand shocks and intertemporal variation in willingness to pay. I estimate a model of dynamic airline pricing accounting for both sources of price adjustments using ...flight‐level data. I use the model estimates to evaluate the welfare effects of dynamic airline pricing. Relative to uniform pricing, dynamic pricing benefits early‐arriving, leisure consumers at the expense of late‐arriving, business travelers. Although dynamic pricing ensures seat availability for business travelers, these consumers are then charged higher prices. When aggregated over markets, welfare is higher under dynamic pricing than under uniform pricing. The direction of the welfare effect at the market level depends on whether dynamic price adjustments are mainly driven by demand shocks or by changes in the overall demand elasticity.
Recent insights into the neural circuits controlling energy balance and glucose homeostasis have rekindled the hope for development of novel treatments for obesity and diabetes. However, many ...therapies contribute relatively modest beneficial gains with accompanying side effects, and the mechanisms of action for other interventions remain undefined. This Review summarizes current knowledge linking the neural circuits regulating energy and glucose balance with current and potential pharmacotherapeutic and surgical interventions for the treatment of obesity and diabetes.
Weight control and metabolic disease have as much or more to do with neural circuits as with food consumption and digestion. Understanding and therapeutically targeting these circuits may lead to better treatments for diabetes and other metabolic disorders.
Over the past two centuries, prevalent models of energy and glucose homeostasis have emerged from careful anatomical descriptions in tandem with an understanding of cellular physiology. More recent ...technological advances have culminated in the identification of peripheral and central factors that influence neural circuits regulating metabolism. This Review highlights contributions to our understanding of peripheral and central factors regulating food intake and energy expenditure.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A carbohydrate-restricted diet is a widely recommended intervention for non-alcoholic fatty liver disease (NAFLD), but a systematic perspective on the multiple benefits of this diet is lacking. Here, ...we performed a short-term intervention with an isocaloric low-carbohydrate diet with increased protein content in obese subjects with NAFLD and characterized the resulting alterations in metabolism and the gut microbiota using a multi-omics approach. We observed rapid and dramatic reductions of liver fat and other cardiometabolic risk factors paralleled by (1) marked decreases in hepatic de novo lipogenesis; (2) large increases in serum β-hydroxybutyrate concentrations, reflecting increased mitochondrial β-oxidation; and (3) rapid increases in folate-producing Streptococcus and serum folate concentrations. Liver transcriptomic analysis on biopsy samples from a second cohort revealed downregulation of the fatty acid synthesis pathway and upregulation of folate-mediated one-carbon metabolism and fatty acid oxidation pathways. Our results highlight the potential of exploring diet-microbiota interactions for treating NAFLD.
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•A low-carbohydrate diet (LCD) improves liver fat metabolism in NAFLD patients•The LCD promotes rapid shifts in the gut microbiota composition of NAFLD patients•The LCD-induced microbial changes are associated with increased circulating folate•The LCD increases folate-dependent one-carbon metabolism gene expression in liver
Mardinoglu et al. use multi-omics to investigate the effects of a carbohydrate-restricted diet in obese NAFLD patients. They show that the diet improves liver fat metabolism, promotes rapid shifts in the gut microbiota, increases circulating folate, and upregulates expression of genes involved in folate-dependent one-carbon metabolism in the liver.
Serotonin 2C receptors (5-HT
2CRs) expressed by pro-opiomelanocortin (POMC) neurons of hypothalamic arcuate nucleus regulate food intake, energy homeostasis and glucose metabolism. However, the ...cellular mechanisms underlying the effects of 5-HT to regulate POMC neuronal activity via 5-HT
2CRs have not yet been identified. In the present study, we found the putative transient receptor potential C (TRPC) channels mediate the activation of a subpopulation of POMC neurons by mCPP (a 5-HT
2CR agonist). Interestingly, mCPP-activated POMC neurons were found to be a distinct population from those activated by leptin. Together, our data suggest that 5-HT
2CR and leptin receptors are expressed by distinct subpopulations of arcuate POMC neurons and that both 5-HT and leptin exert their actions in POMC neurons via TRPC channels.
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► 5-HT2CRs excite arcuate POMC neurons independent of altering GIRK channel activity ► Arcuate POMC 5-HT2CRs activate a Na
+/Ca
2+ permeable mixed-cation conductance ► 5-HT2CR-induced excitation of arcuate POMC neurons requires a putative TRPC channel ► 5-HT2CR- and LepR-activated arcuate POMC neurons are anatomically segregated
Melanocortin 4 receptors (MC4Rs) in the central nervous system are key regulators of energy and glucose homeostasis. Notably, obese patients with MC4R mutations are hyperinsulinemic and resistant to ...obesity-induced hypertension. Although these effects are probably dependent upon the activity of the autonomic nervous system, the cellular effects of MC4Rs on parasympathetic and sympathetic neurons remain undefined. Here, we show that MC4R agonists inhibit parasympathetic preganglionic neurons in the brainstem. In contrast, MC4R agonists activate sympathetic preganglionic neurons in the spinal cord. Deletion of MC4Rs in cholinergic neurons resulted in elevated levels of insulin. Furthermore, re-expression of MC4Rs specifically in cholinergic neurons (including sympathetic preganglionic neurons) restores obesity-associated hypertension in MC4R null mice. These findings provide a cellular correlate of the autonomic side effects associated with MC4R agonists and demonstrate a role for MC4Rs expressed in cholinergic neurons in the regulation of insulin levels and in the development of obesity-induced hypertension.
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► MC4Rs inhibit parasympathetic preganglionic neurons in the brainstem ► MC4Rs activate sympathetic preganglionic neurons in the spinal cord ► MC4Rs expressed by cholinergic neurons regulate insulin levels ► MC4Rs expressed by cholinergic neurons contribute to obesity-induced hypertension.
The CNS melanocortin 4 receptor (MC4R) and the autonomic nervous system represent key regulators of metabolism. Sohn et al. demonstrate the reciprocal regulation of sympathetic and parasympathetic tones by MC4Rs and its contribution to insulin regulation and obesity-induced hypertension.
Cellular lipid requirements are achieved through a combination of biosynthesis and import programs. Using isotope tracer analysis, we show that type I interferon (IFN) signaling shifts the balance of ...these programs by decreasing synthesis and increasing import of cholesterol and long chain fatty acids. Genetically enforcing this metabolic shift in macrophages is sufficient to render mice resistant to viral challenge, demonstrating the importance of reprogramming the balance of these two metabolic pathways in vivo. Unexpectedly, mechanistic studies reveal that limiting flux through the cholesterol biosynthetic pathway spontaneously engages a type I IFN response in a STING-dependent manner. The upregulation of type I IFNs was traced to a decrease in the pool size of synthesized cholesterol and could be inhibited by replenishing cells with free cholesterol. Taken together, these studies delineate a metabolic-inflammatory circuit that links perturbations in cholesterol biosynthesis with activation of innate immunity.
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•Identification of a cholesterol metabolism-type I interferon (IFN) inflammatory circuit•Type I interferon reprograms cholesterol homeostasis•Perturbing cholesterol synthesis engages type I IFN signaling•STING/TBK1 links cholesterol metabolism with type I interferon pathway
Cholesterol metabolism and type I interferon response are co-regulated in macrophages, creating an immuno-metabolic circuit that allows innate immune cells to coordinate metabolism changes with immune activation required for antiviral responses.
This paper provides miscellaneous taxonomic updates for diurnal velvet ants in the USA. Six valid species of Dasymutilla Ashmead, 1899, one valid species of Ephuta Say, 1836 and six valid species of ...Pseudomethoca Ashmead, 1896 are regarded. Two new species are described: Pseudomethoca peremptrix sp. nov. and P. sonorae sp. nov. The female formerly associated with Dasymutilla zelaya (Blake, 1871) is recognized as a color variant of D. vestita (Lepeletier, 1845). Sixteen new synonymies are proposed: Dasymutilla chisos Mickel, 1928, syn. nov. under D. gloriosa (Saussure, 1868); D. cotulla Mickel, 1928, syn. nov., D. homole Mickel, 1928, syn. nov. and D. vandala Mickel, 1928, syn. nov. under D. vestita (Lepeletier, 1845); D. dorippa Mickel, 1928, syn. nov. under D. flammifera Mickel, 1928; D. ocydrome Mickel, 1928, syn. nov. under D. connectens (Cameron, 1895); Mutilla phaon Fox, 1899, syn. nov. under D. pseudopappus (Cockerell, 1895); M. zelaya Blake, 1871, syn. nov. under D. gorgon (Blake, 1871); Ephuta tentativa Schuster, 1951, syn. nov. under E. scrupea Say, 1836; P. dentifrontalis Bradley in Mickel, 1924, syn. nov. under P. athamas (Fox, 1899); P. albicoma Mickel, 1924, syn. nov., P. contumeliosa Mickel, 1935, syn. nov., P. manca Mickel, 1924, syn. nov. and P. oculissima Mickel, 1924, syn. nov. under P. contumax (Cresson, 1865); M. aeetis Fox, 1899, syn. nov. under P. sanbornii (Blake, 1871); and P. (Nomiaephagus) vanduzei Bradley, 1916, syn. nov. under P. wickhami (Cockerell & Casad, 1895).
The application market for Photonic Integrated Circuits (PICs) is rapidly growing. Photonic integration is the dominant technology in high bandwidth communications and is set to become dominant in ...many fields of photonics, just like microelectronics in the field of electronics. PICs offer compelling performance advances in terms of precision, bandwidth, and energy efficiency. To enable uptake in new sectors, the availability of highly standardized (generic) photonic integration platform technologies is of key importance as this separates design from technology, reducing barriers for new entrants. The major platform technologies today are Indium Phosphide (InP)-based monolithic integration and Silicon Photonics. In this perspective paper, we will describe the current status and future developments of InP-based generic integration platforms.
•Stability of WPI-stabilized fish O/W emulsions was dependent on pH.•At pH 3 and 5, flocculation and creaming occurred due to WPI-XG-LBG complexes.•At pH 3 and 5, XG or XG-LBG mixtures increased ...droplet sizes and viscosity.•At pH 7, emulsions with XG-LBG mixtures were the most stable to creaming.•XG-LBG complexes reduced lipid oxidation of emulsions at both pH 3 and 7.
The impact of pH on the physicochemical properties of 10% menhaden oil-in-water (O/W) emulsions containing 2% whey protein isolate (WPI) and 0.1% xanthan (XG)-locust bean gum (LBG) mixtures was investigated. The O/W emulsions containing 0.1% XG-LBG mixtures were compared to emulsions with 0.1% XG and 0.1% LBG. The results indicated that stability is dependent on pH and biopolymer type. At both pH 3 and 5, emulsions containing either XG or XG-LBG mixtures had large particle sizes, viscosity, droplet aggregation, and creaming index, resulting in poor physical stability which can be related to the adsorbed protein-polysaccharide interactions. At pH7, the XG-LBG emulsions showed the greatest resistance to phase separation and resulted in stable emulsions. Lipid oxidation measurements also indicated that XG-LBG mixtures can be used to form stable emulsions at pH 3 and pH 7. These results have significant implications for the development of novel structures containing lipid phases susceptible to lipid oxidation.
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