Effects of lecithin in salad dressing on the plasma appearance of fat-soluble micronutrients consumed in salads: contributions of chylomicrons and large VLDL

ABSTRACT Provitamin A carotenoids, tocopherols, and phylloquinone, as the major fat-soluble micronutrients in salad vegetables, play essential roles in maintaining various physiological processes, such as cell differentiation and proliferation, normal organogenesis, and blood clotting. The non-provitamin A carotenoids, particularly lutein, zeaxanthin, and lycopene are important for maintaining ocular health and preventing chronic diseases. The intestinal uptake of fat-soluble micronutrients involves both simple diffusion and receptor-mediated transport. Various exogenous factors are able to affect the uptake process, e.g. food matrix and processing, dietary fat and fiber, and nutrient species and stereoisomers. Transferring fat-soluble micronutrients into the blood circulation depends on the normal synthesis of apolipoproteinB (apoB) and apoB-containing lipoprotein, which is promoted by the presence of sufficient lipids and suppressed by insulin. Overall, dietary fat is an elementary factor regulating the absorption of fat-soluble micronutrients. Lecithin may influence the bioavailability of fat-soluble micronutrients. The role of the large very-low-density lipoprotein (VLDLA) plasma fraction in postprandial fat-soluble micronutrient transport is not clearly defined. Therefore, we conducted a human study to investigate the effects of the lecithin/oil ratio in salad dressing on the absorption of: 1) carotenoids, phylloquinone, and tocopherols from salad vegetables; 2) retinyl palmitate formed in the intestine from the provitamin A carotenoids. An additional objective was to investigate the origin of plasma chylomicrons and VLDLA and their roles in the transport of the absorbed fat-soluble micronutrients. Healthy women (n = 12) each consumed three salads with salad dressings containing: 1) 4 g soybean oil and 0 g hydroxylated soy lecithin (Solec® 8120, Solae, St. Louis, MO); 2) 3.8 g soybean oil and 0.2 g Solec® 8120; or 3) 3.2 g of soybean oil and 0.8 g Solec® 8120. The order in which the salads were consumed was randomly assigned according to a Williams Latin square design; salads were separated by ≥ 2 weeks. Blood was collected at baseline and 2, 3.5, 5, 7, and 9.5 h postprandially. Chylomicrons and VLDLA fractions were analyzed by HPLC with coulometric array electrochemical detection. ApoB-48 and apoB-100 contents in chylomicrons and VLDLA were determined by ELISA. There were no significant differences among the salad dressings in the resulting AUC values of the fat-soluble micronutrients in the chylomicron and VLDLA fractions. The exception was a decrease in the AUC value of phylloquinone in the chylomicron fraction when the salad dressing containing 0.8 g was compared with that containing 0 g Solec® 8120 (P \u3c 0.02). The AUC values for α-carotene, β-carotene, lycopene, retinyl palmitate, and phylloquinone were substantially higher in the VLDLA than in the chylomicron fraction (P \u3c 0.05). Both chylomicron and VLDLA fractions contained apoB-48 and apoB-100. ApoB-48 and apoB-100 were predominantly found in the VLDLA fraction (P \u3c 0.0001). The AUC value of apoB-100 in VLDLA was significantly higher than that of apoB-48 in chylomicrons (P \u3c 0.0001). We concluded that the hydroxylated soy lecithin in the amounts added to the salad dressing did not enhance the absorption of carotenoids, retinyl palmitate, phylloquinone, or tocopherols. The majority of the newly absorbed carotenoids, retinyl palmitate, and phylloquinone, as well as enterogenous (apoB-48) and hepatogenous (apoB-100) lipoprotein particles, were contained within large VLDL. Thus this lipoprotein subfraction has a major role in the transport of newly absorbed carotenoids and fat-soluble vitamins

Structural study of yeast SNARE proteins on membrane by EPR

Membrane fusion is a basic biophysical process involved in cell\u27s physiological activities. The value of studying the exocytosis of mammalian cells and yeast cells lies in that a highly conserved SNARE (Soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein super family mediates this process and is proposed to be the core protein machinery for the membrane. The SNARE proteins located on plasma membrane and vesicle membrane are assembled together to form a trans-SNARE bridging two separate membranes and initiating membrane.;My research centers on how SNARE assembly involved in yeast cells\u27 exocytosis promotes membrane fusion between yeast vesicle and plasma membrane. Site-directed spin labeling (SDSL) and electron paramagnetic resonance (EPR) are well established techniques in membrane protein structural study. Fluorescent labeled Lipid mixing assay is employed to test the functional activity of SNARE. The data from trans-SNARE assembly on membrane indicates its potential catalyst role in membrane fusion; The transmembrane organization of neural syntaxin-analogue Sso1p is a well defined alpha helix across membrane based on accessibility profile of magnetic reagents; Transmembrane domain of Sso1p tends to form oligomers of stoichiometries ranging from 3 to 6 in the membrane, which likely act as a scaffold of formation and clustering of multimeric trans-SNARE supra complex prior to lipid mixing; Sso1p TMD conformational change involved in the transition from trans- to cis-SNARE is also disclosed by EPR spectra, shedding light on the structural and temporal relationship between SNARE assembly intermediates and substeps of membrane fusion

IRGAN: A Minimax Game for Unifying Generative and Discriminative Information Retrieval Models

This paper provides a unified account of two schools of thinking in information retrieval modelling: the generative retrieval focusing on predicting relevant documents given a query, and the discriminative retrieval focusing on predicting relevancy given a query-document pair. We propose a game theoretical minimax game to iteratively optimise both models. On one hand, the discriminative model, aiming to mine signals from labelled and unlabelled data, provides guidance to train the generative model towards fitting the underlying relevance distribution over documents given the query. On the other hand, the generative model, acting as an attacker to the current discriminative model, generates difficult examples for the discriminative model in an adversarial way by minimising its discrimination objective. With the competition between these two models, we show that the unified framework takes advantage of both schools of thinking: (i) the generative model learns to fit the relevance distribution over documents via the signals from the discriminative model, and (ii) the discriminative model is able to exploit the unlabelled data selected by the generative model to achieve a better estimation for document ranking. Our experimental results have demonstrated significant performance gains as much as 23.96% on Precision@5 and 15.50% on MAP over strong baselines in a variety of applications including web search, item recommendation, and question answering.Comment: 12 pages; appendix adde

On instability of a generic compressible two-fluid model in R3\mathbb R^3

We are concerned with the instability of a generic compressible two-fluid model in the whole space $\mathbb{R}^3$, where the capillary pressure $f(\alpha^-\rho^-)=P^+-P^-\neq 0$ is taken into account. For the case that the capillary pressure is a strictly decreasing function near the equilibrium, namely, $f'(1)<0$, Evje-Wang-Wen established global stability of the constant equilibrium state for the three-dimensional Cauchy problem under some smallness assumptions. Recently, Wu-Yao-Zhang proved global stability of the constant equilibrium state for the case $P^+=P^-$ (corresponding to $f'(1)=0$). In this work, we investigate the instability of the constant equilibrium state for the case that the capillary pressure is a strictly increasing function near the equilibrium, namely, $f'(1)>0$. First, by employing Hodge decomposition technique and making detailed analysis of the Green's function for the corresponding linearized system, we construct solutions of the linearized problem that grow exponentially in time in the Sobolev space $H^k$, thus leading to a global instability result for the linearized problem. Moreover, with the help of the global linear instability result and a local existence theorem of classical solutions to the original nonlinear system, we can then show the instability of the nonlinear problem in the sense of Hadamard by making a delicate analysis on the properties of the semigroup. Therefore, our result shows that for the case $f'(1)>0$, the constant equilibrium state of the two-fluid model is linearly globally unstable and nonlinearly locally unstable in the sense of Hadamard, which is in contrast to the cases $f'(1)<0$ and $P^+=P^-$ (corresponding to $f'(1)=0$) where the constant equilibrium state of the two--fluid model is nonlinearly globally stable.Comment: 17. arXiv admin note: substantial text overlap with arXiv:2204.10706, arXiv:2108.06974, arXiv:2010.1150