Regulation of mouse and human mast cell development, survival and function by stem cell factor, the ligand for the c-kit receptor

Stem cell factor (SCF), the ligand for the receptor (SCFR) that is encoded by the c-kit proto-oncogene, has many important effects in mouse and human mast cell development, survival, and function. SCF can promote mast cell survival by suppressing apoptosis, induce mast cell hyperplasia in murine rodents, experimental primates and humans, directly induce SCFR-dependent mast cell mediator release, and significantly modulate the extent of mast cell activation by Fc epsilon RI-dependent mechanisms. These findings raise several clinical issues and, in some cases, point to potentially significant therapeutic opportunities.     

The effects of intraruminal infusions of urea on the voluntary intake and milk production of cows receiving grass silage diets

Responses of dairy cows given silage diets to the intraruminal infusion of urea in progressively increasing doses were studied in four experiments, two with non-lactating cows and two with lactating cows. No clinical symptoms of NH3 toxicity were observed in any of the experiments. When urea was infused continuously, silage intake was depressed (P less than 0.05) when the total supply of N exceeded the equivalent of 250 g crude protein (CP)/kg DM in the total diet. However, when the urea load was administered twice daily, as opposed to continuously, intake depression (P less than 0.05) occurred at the equivalent of 170 g CP/kg DM. At the higher doses of urea, concentrations of NH3 in peripheral blood increased and were accompanied by increased concentrations of glucose and reduced levels of insulin in plasma. In general, responses of milk production followed those of silage intake but there was evidence of greater proportional reductions in the yield of lactose relative to that of fat and protein. It is concluded that the voluntary intake of high-protein silages may be depressed by factors associated with high rates of absorption of NH3 from the rumen.     

Hypnotic effect of GABA from rice germ and/or tryptophan in a mouse model of pentothal-induced sleep

γ-Aminobutyric acid (GABA), a primary inhibitory neurotransmitter, and tryptophan (Trp), a substrate for melatonin, are found in functional foods and exert hypnotic effects. The hypnotic effects of 3 doses of GABA and a combined-preparation of GABA and Trp (GABA+Trp) were investigated in mice. Hypnotic activity was evaluated using pentothal-induced sleep time testing. Treatments included low, middle, and high doses of GABA and GABA+Trp. Low doses of GABA (low-GABA) and low-GABA+Trp reduced sleep latency and significantly (p<0.05) prolonged the sleep time induced by pentothal, compared with controls, although the melatonin concentration in the serum was not affected. On the other hand, the adenosine A1 receptor (AA1R) immunoreactivity in the suprachiasmatic nucleus of the hypothalamus was significantly (p<0.05) increased after administration of low-GABA and/or low-GABA+Trp, compared to controls. Low doses of GABA and/or Trp cause hypnotic effects that may be related to AA1R activation.     

NH3 removal using the dielectric barrier discharge plasma-V-TiO2 photocatalytic hybrid system

This study investigates the photocatalytic performance of V-TiO₂ for removal of highly concentrated ammonia (1,000 ppm) in the dielectric barrier discharge (DBD), plasma-photocatalytic, hybrid system. The V (1.0, 5.0, 10.0 mol-%)-TiO₂ photocatalysts were prepared by using the conventional sol-gel method. Their surface areas were decreased with increasing vanadium component. The UV-visible absorption band slightly shifted to more visible wavelengths in V-TiO₂ compared to that in pure TiO₂. The NH₃-TPD result confirmed that the ability of NH₃ adsorption on the surface of V-TiO₂ increased with increasing vanadium content, and was maximized for 5.0-mol% V-TiO₂. The NH₃ decomposition was enhanced with the photocatalyst compared to the decomposition rate without catalysts, while the decomposition was further increased with the applied plasma voltage. The NH₃ decomposition reached 90% after 400 min at an applied plasma voltage of 10.0 kV, and various intermediates, such as-NH₂,-NH, and NO, were also identified by using the Fourier transform infrared (FT-IR) spectra. In addition, the NH₃ decomposition reached 100% in the plasma-5.0 mol% V-TiO₂, photocatalytic, hybrid system after 25 min, compared to 98% in the pure V-TiO₂ photocatalytic system after 150 min. In addition, the various undesirable byproducts were depressed when V-TiO₂ photocatalyst was used compared to that in the non-catalytic system.     

Three naphthalenes from root bark of Hibiscus syriacus

Three new naphthalenes, designated as syriacusins A-C, were isolated from the root bark of Hibiscus syriacus. These compounds were identified as 2,7-dihydroxy-6-methyl-8-methoxy-1-naphthalenecarbaldehyde, 2-hydroxy-6-hydroxymethyl-7,8-dimethoxy-1-naphthalenecarbaldehyde, 1-carboxy-2,8-dihydroxy-6-methyl-7-methoxynaphthalenecarbolactone (1-->8), respectively, on the basis of various spectral studies. The compounds inhibited lipid peroxidation with IC50s of 0.54, 5.90 and 1.02 micrograms ml-1, respectively. The first compound also showed cytotoxicity against some human cancer cell lines with an ED50 of 1.5-2.4 micrograms ml-1.