Stilbenes from the roots of Pleuropterus ciliinervis and their antioxidant activities

Two stilbene glycosides, pieceid-2"-O-gallate and pieceid-2"-O-coumarate, were isolated from the MeOH extract of the roots of Pleuropterus ciliinervis Nakai (Polygonaceae), together with two known compounds, resveratrol and pieceid. Their structures were determined spectroscopically, particularly by 2D NMR spectroscopic analysis. The antioxidant activities of stilbenes isolated were determined in vitro against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, superoxide radicals and by determining their lipid peroxidation inhibitory activities. Among the compounds isolated, pieceid-2"-O-gallate had the most potent inhibitory scavenging effect on DPPH, superoxide radicals and upon lipid peroxidation inhibition with IC50 values of 16.5, 23.9 and 5.1 microM, respectively.     

Identification,expression, and import of components 17 and 23 of the inner mitochondrial membrane translocase from Arabidopsis

Characterization of components 17 and 23 of the inner mitochondrial membrane translocase (TIM17:23) from Arabidopsis indicated that there were three genes present for TIM17 and TIM23 and two for TIM44. AtTIM17 differed from the yeast (Saccharomyces cerevisiae) and mammalian homologs in that two genes encoded proteins that were longer and one gene encoded a shorter protein. All Arabidopsis TIM23 predicted proteins appeared to lack the first 34 amino acids compared with yeast TIM23. All AtTIM17 and AtTIM23 genes were expressed but displayed different tissue and developmental profiles. Complementation of deletion mutants in yeast indicated that for AtTIM17, the extension at the C terminus not present in yeast had to be removed to achieve complementation, whereas for TIM23, a preprotein and amino acid transporter domain had to be present for complementation. Import assays with AtTIM17 and AtTIM23 indicated that they both contained internal signals for integration into the inner mitochondrial membrane in a membrane potential-dependent manner. The C terminus of imported AtTIM17-2 was susceptible to degradation by externally added protease with intact mitochondria. Removal of the 85 C-terminal amino acids resulted in import and full protection of the truncated protein. This suggests that the novel extension at the C terminus of AtTIM17-2 links the outer and inner membrane in a manner analogous to yeast TIM23.     

Arsenic trioxide enhances radiation response of 9L glioma in the rat brain

Arsenic trioxide (ATO) at low doses induces leukemia cells to undergo apoptosis and at higher doses causes blood flow to solid tumors to shut down. To determine whether a potential synergistic interaction exists between ATO at the non-toxic dose level in the rat and radiation, the present study was carried out with orthotopic 9L malignant gliomas growing in the brains of rats. Animals died within 50 days of treatment when 12-day-old 9L gliomas growing in the brain of Fischer rats were treated with either the drug alone (8 mg/kg) or radiation alone (25 Gy). In contrast, the overall tumor cure rate exceeded 50% at a follow-up time of 120 days after the combined treatment with radiation and ATO. Long-term surviving animals showed no clinical or disproportionately enhanced histopathological changes in the brain parenchyma. Early changes in tumor physiology showed that the vascular leakage of FITC-dextran conjugates was apparent within 8 h of drug administration. Last, the use of diffusion magnetic resonance imaging as an early surrogate marker of therapeutic efficacy corroborated the effects of drug with and without radiation on brain histology and animal survival.     

Switch-of-function mutants based on morphology classification of Ras superfamily small GTPases

Signaling proteins from the same family can have markedly different roles in a given cellular context. Here, we show that expression of one hundred constitutively active human small GTPases induced cell morphologies that fell into nine distinct classes. We developed an algorithm for pairs of classes that predicted amino acid positions that can be exchanged to create mutants with switched functionality. The algorithm was validated by creating switch-of-function mutants for Rac1, CDC42, H-Ras, RalA, Rap2B, and R-Ras3. Contrary to expectations, the relevant residues were mostly outside known interaction surfaces and were structurally far apart from each other. Our study shows that specificity in protein families can be explored by combining genome-wide experimental functional classification with the creation of switch-of-function mutants.     

Hot-water extract from mycelia of Cordyceps sinensis as a substitute for antibiotic growth promoters

Broiler chicks were orally dosed with a hot-water extract of mycelia from Cordyceps sinensis (CS-HW) to assess possible substitution of Avilamycin as an antibiotic growth promoter (AGP). The growth performance (body weight gain and survivability) and the health index (the microflora in the small intestines and the antibody titer to Newcastle disease virus) of chicks were significantly improved in the CS-HW (600 mg/kg diet) and the Avilamycin (20 mg/kg diet) fed group in comparison with the control group (p<0.05). The Avilamycin-fed group and the CS-HW-fed group had similar growth performances but the latter gave a better microbial flora in the small intestines. These results indicate that CS-HW enhances the physiological activity in chicks and can be used as a substitute for AGPs.     

Comparison of media for enumeration of Clostridium perfringens from foods

Many media have been developed to enumerate Clostridium perfringens from foods. In this study, six media [iron sulfite (IS) agar, tryptose sulfite cycloserine (TSC) agar, Shahidi Ferguson perfringens (SFP) agar, sulfite cycloserine azide (SCA), differential clostridial agar (DCA), and oleandomycin polymyxin sulfadiazine perfringens (OPSP) agar] were compared in a prestudy, of which four (IS, TSC, SCA, and DCA) were selected for an international collaborative trial. Recovery of 15 pure strains was tested in the prestudy and recovery of one strain from foodstuffs was tested in the collaborative trial. Results from the prestudy did reveal statistical difference of the media but recoveries on all media were within the microbiological limits (+/-30%) of IS, which was set as a reference medium. Recoveries on the media tested in the collaborative trial were statistically different as well, but these differences were of no microbiological-analytical relevance. Food matrices did not affect the recovery of C. perfringens in general. DCA and SCA, in particular, are labor-intensive to prepare and DCA frequently failed to produce black colonies; gray colonies were quite common. Since IS medium is nonselective, it was concluded that TSC was the most favorable medium for the enumeration of C. perfringens from foods.