Direct stimulatory effect of ghrelin on pituitary release of LH through a nitric oxide-dependent mechanism that is modulated by estrogen

Ghrelin, a gut peptide with key actions on food intake and GH secretion, has been recently recognized as potential regulator of reproductive function. Thus, in adult female rats, ghrelin has been proven to modulate GnRH/LH secretion, with predominant inhibitory effects in vivo. We analyze herein potential direct pituitary effects of ghrelin on basal and GnRH-stimulated gonadotropin secretion in prepubertal female rats, and its interplay with ovarian inputs, nitric oxide (NO), and hypothalamic differentiation. In the experimental setting, pituitaries from intact and ovariectomized prepubertal female rats were challenged with ghrelin in vitro and LH secretion was monitored. Our results demonstrate that 1) ghrelin consistently stimulated in vitro pituitary LH secretion under different experimental conditions; 2) the sensitivity to ghrelin, expressed either as the minimal effective dose or the amplitude of the LH response, was modulated by ovarian inputs; 3) the blockade of estrogen action significantly augmented the stimulatory effect of ghrelin; 4) the stimulatory effect of ghrelin on LH secretion required proper NO synthesis; and 5) the ability of ghrelin to elicit LH secretion in vitro was preserved after alteration (masculinization) of brain sexual differentiation. Overall, our present data reinforce the concept that ghrelin participates in the control of LH secretion, with potential stimulatory actions at the pituitary level that require the presence of NO and are modulated by ovarian signals.     

Cover Image,Volume 98, Issue 8

The cover image, by Rosario Sánchez‐Gómez et al., is based on the Research Article The Microvine, a plant model to study the effect of vine‐shoot extract on the accumulation of glycosylated aroma precursors in grapes, DOI: 10.1002/jsfa.8802 .

     

High performance liquid chromatographic determination of soluble carbohydrates in commercial drinks

High performance liquid chromatography was carried out to determine the soluble sugar content in canned soft drinks and commercial fruit juices stored in different types of containers. The total amount of sugars ranged from 9.2 to 13.5 g 100 ml^?1 for the soft drinks, 10 to 14 g 100 ml^?1 in fruit nectars and 3 g 100 ml^?1 in tomato juice. The individual sugar content of soft drinks varied between different batches, although the total amount remained fairly constant for each kind of drink or juice. Only in tomato juice where sucrose was not present, did the values for glucose and fructose remain constant.     

Micropores and Their Relationship with Carotenoids Stability: A New Tool to Study Preservation of Solid Foods

Carotenoids were encapsulated by means of coacervation by using a nanostructured material (NE) prepared with alginate/zeolite valfor 100 (1:3) and another that was non-nanostructured (AA) prepared with alginate at 2 %. The diameter of the AA and NE capsules was ≈1,200 μm. The NE protected the carotenoids at higher water activities (a _w) than the AA. The highest retention of carotenoids (7,200 mg/kg dry solids for NE and 2,230 mg/kg dry solids for AA) was observed at water activities corresponding to the minimal integral entropy (≈0.35–0.45 for NE and ≈0.1 for AA). According to the enthalpy–entropy compensation, the water adsorption in the AA capsules was enthalpy driven at a _w range of 0.115–0.973. However, the NE showed two zones: (1) at low a _w (0.115–0.4), the water adsorption was controlled by entropy and (2) over an a _w range of 0.4–0.973, controlled by enthalpy. Atomic force microscope images, moisture content corresponding to micropore volume and thermodynamic properties suggest that the adsorption process and the carotenoids stability were controlled by entropic barriers when the water molecules were adsorbed in the micropores (nanopores with pore diameter <2 nm). The practical use of these results is that increasing the number of micropores in the solid matrix of wall materials is possible to improve the preservation of nutrients and functional substances during processing and storage of foods.     

Behavioral modeling of pipeline ADC building blocks

This paper presents accurate behavioral models for the basic building blocks of pipeline data converters with emphasis on the MDAC circuit. These models take into account major circuit‐level non‐idealities, including small‐ and large‐signal effects, as well as the impact of switch‐on resistance effects and thermal noise contributions. The behavioral models have been validated against transistor‐level simulations under different scenarios, showing in all cases a worst‐case deviation of 0.3 bit effective resolution. Copyright © 2011 John Wiley & Sons, Ltd.     

Physical activation of graphene: An effective,simple and clean procedure for obtaining microporous graphene for high-performance Li/S batteries

Graphene nanosheets are a promising scaffold to accommodate S for achieving high performance Li/S battery. Nanosheet activation is used as a viable strategy to induce a micropore system and further improve the battery performance. Accordingly, chemical activation methods dominate despite the need of multiple stages, which slow down the process in addition to making them tiresome. Here, a three-dimensional (3D) N-doped graphene specimen was physically activated with CO₂, a clean and single step process, and used for the preparation of a sulfur composite (A-3DNG/S). The A-3DNG/S composite exhibited outstanding electrochemical properties such as an excellent rate capability (1,000 mAh·g⁻¹ at 2C), high reversible capacity and cycling stability (average capacity ~ 800 mAh·g⁻¹ at 1C after 200 cycles), values which exceed those measured in chemically activated graphene. Therefore, these results support the use of physical activation as a simple and efficient alternative to improve the performance of carbons as an S host for high-performance Li-S batteries.

     

Steam gasification of a cellulose surrogate over a fluidizable Ni/α‐alumina catalyst: A kinetic model

Catalytic steam gasification of a cellulose surrogate using a fluidizable Ni/α‐alumina catalyst is presented. Experiments were carried out in the CREC fluidized riser simulator. On this basis, a reaction network and a kinetic model for biomass catalytic steam gasification were proposed. This kinetic model was developed using a sound reaction engineering approach where reaction rates for various species are the result of the algebraic addition of dominant reactions. The modeling procedure also included the decoupled determination of intrinsic kinetic parameters and adsorption constants as allowed in the CREC riser simulator. The implemented approach eliminates overparametrization with successfully parameter correlation. Numerical regression of the experimental data led to intrinsic kinetic parameters with narrow spans showing that the proposed kinetic model satisfactorily describe the catalytic conversion of glucose under the selected gasification conditions. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Supercritical water oxidation of flammable industrial wastewaters: economic perspectives of an industrial plant

BACKGROUND: Supercritical water oxidation (SCWO) is a promising technology that respects the environment, destroys wastes and allows energy recovery. This process has been applied to many model compounds and real wastewaters at laboratory scale. However, SCWO treatments at pilot plant scale of real wastewaters are scarce. The application of this technology to industrial wastewaters has drawbacks such as corrosion, salt deposition and high cost, so industrial scale‐up has been delayed. RESULTS: In a first stage, for safety reasons the feasibility of SCWO applied to flammable industrial wastewaters was evaluated at laboratory scale in an isothermal plug flow reactor with low concentrations (3–10 g COD L^?1), at a constant pressure of 250 bar and at different temperatures in the range 350–500 °C. In a second stage, experiments were conducted with much higher concentrations (20–90 g COD L^?1) in a SCWO reactor at pilot plant scale. Experiments at pilot plant scale demonstrated the possibility of working under autothermal conditions and the results were used to estimate the treatment costs for a SCWO plant with a capacity of 1 m³ h^?1. CONCLUSION: Results demonstrated the technical feasibility of using a SCWO process to treat flammable industrial wastewater at pilot plant scale due to the absence of operational drawbacks related to the flammability of this wastewater, such as plugging, pressurization or preheating problems and uncontrolled reactions (explosion, etc.). The economic feasibility was demonstrated, especially bearing in mind the energy recovery optimization. Copyright © 2011 Society of Chemical Industry