Dietary Fat-Accelerating Leptin Signaling Promotes Protumorigenic Gastric Environment in Mice.

Excess of fat intake leads to obesity and causes a variety of metabolic diseases and cancer. We previously demonstrated that high-lard diet induces intestinal metaplasia, a precancerous lesion of the stomach mediated by leptin signaling. This study aims to investigate which kinds of dietary fat cause the intestinal metaplasia onset. We fed eight kinds of high-fat diets (HFDs) of animal or plant origin to mice evaluated their effect on gastric pathogenesis. Five types of dietary fat were divided according to their observed effects: Obese with high metaplasia (group I; beef tallow, lard, and hydrogenated coconut oil), non-obese with high metaplasia (group II; linseed oil), obese without metaplasia (group III; corn oil and olive oil), non-obese without metaplasia (group IV, soybean oil) and lean without metaplasia (group V; cocoa butter). The group I and II diets induced leptin, phosphorylated leptin receptor (ObR), signal transducer and activator 3 (STAT3), and increased intracellular ß-catenin accumulation in the stomach. Moreover, mice fed these HFDs with 1-methyl-3-nitro-1-nitrosoguanidine (MNNG), a gastric carcinogen, and further accelerated dysplasia in the stomach. Lactobacillus occupancy in the stomach increased in all HFDs except hydrogenated coconut oil. Our findings suggest that HFDs inducing leptin signaling accelerate the enhancement of protumorigenic gastric microenvironment independent of body mass gain or microbiome changes.

Spin-probe ESR study on the dynamics of liquid molecules in the MCM-41 nanochannel: temperature dependence on 2-propanol and water.

A spin-probe ESR study has been made on the dynamics of 2-propanol and water molecules in the nanochannel of MCM-41 at various temperatures. In the former system, 2-propanol is separated into two phases: one with molecules immobilized in the ESR time scale and the other with mobile ones, even at temperatures more than 40 degrees higher than the bulk melting point. In the case of water, on the other hand, only the "immobilized" water was detected at a temperature as high as 313 K. At higher temperature, spin-probe molecule undergoes anisotropic rotational diffusion to reduce resistance from the solvent molecules in the nanochannel. These results are explained in relation to the intermolecular network intensified in the nanochannel. Static as well as dynamic structures of these solutions have been discussed.

Entrapment of organic solutes by the water cage in the nanochannel of MCM-41.

The effect of MCM-41 on the ESR spectrum of an aqueous spin probe solution was observed. The sharp ESR spectrum turns into a rather broad characteristic one leaving a sharper signal as the minor component, immediately after the addition of MCM-41 powder to the system. This observation indicates that MCM-41 traps the solute molecule into the nanochannel by letting the solvent water form a rather stable molecular cage, since the ESR line shape indicates that the nitroxide radical undergoes anisotropic rotation without being adsorbed on the wall. Thermodynamic parameters for this process are estimated from the temperature dependencies of the trapping efficiency. This process is explained in terms of the surface enthalpy of the liquid specifically intensified in the nanospace.

Spin-probe ESR study on the entrapment of organic solutes by the nanochannel of MCM-41 in benzene.

An ESR study has been made on the adsorption of three types of aminoxyl radicals with different substituent groups in the nanochannel of MCM-41 in benzene. In the suspensions of MCM-41, all the aminoxyl radicals, usually called as spin probes, show the ESR spectra composed of two signals: the main broader one from the spin probes trapped in the nanochannel, and a sharp minor signal from those in the bulk. The spin probes adsorbed in the nanochannel retain considerable mobility especially at higher temperatures over 300 K. When fumed silica, having a surface structure similar to that of MCM-41, is employed, on the other hand, the relatively hydrophobic spin probe mainly remains in the bulk, but the hydrophilic one is mostly adsorbed and immobilized rigidly. From these results, the adsorption by the MCM-41 nanochannel in benzene is characterized by medium selectivity and considerable motional allowance to the adsorbate molecule. The mobility of the spin probe in the MCM-41 nanochannel increases and the adsorption efficiency decreases by either of the following changes made to the system: (a) increasing the channel diameter, (b) increasing the hydrophobicity of the spin probe, (c) adding a small amount of 2-propanol in the solution, (d) methylation of the surface OH groups of the nanochannel, and (e) elevating the system temperature. A model of this special type of adsorption has been proposed on the basis of the thermodynamic parameters and the ESR spectra for the modified systems including those with different solvents.