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At least 1,621 records · Page 90Linked to original sources
PubMed2002

Susceptibility of recombinant porcine endogenous retrovirus reverse transcriptase to nucleoside and non-nucleoside inhibitors.

Transplantation of organs, tissues or cells from pigs to humans could be a potential solution to the shortage of human organs for transplantation. Porcine endogenous retroviruses (PERVs) remain a major safety concern for porcine xenotransplantation. Thus, finding drugs that could be used as virological prophylaxis (or therapy) against PERV replication would be desirable. One of the most effective ways to block retroviral multiplication is to inhibit the enzyme reverse transcriptase (RT) which catalyzes the reverse transcription of viral RNA to proviral double-stranded DNA. We report here the cloning and expression of PERV RT and its susceptibility to several inhibitors. Our data demonstrate PERV susceptibility in vitro to the triphosphorylated nucleoside analog of zidovudine (AZT) and to ddGTP and to a lesser extent to ddTTP but almost no susceptibility to the non-nucleoside RT inhibitors tested.

Amino Acid Sequence↗
PubMed2006

Cadmium restores in vitro splicing activity inhibited by zinc-depletion.

Zinc (Zn)-depletion inhibits the second step of RNA splicing, namely exon-ligation. To investigate the effects of cadmium (Cd) and other metal ions on RNA splicing inhibited by Zn-depletion, we measured in vitro splicing activities in the presence of these metals. Zn-depletion in the splicing reaction mixture was achieved by addition of a Zn-chelator, 1,10-phenanthroline. Cd(II) at 1, 5 and 10 microM restored the splicing activity to 2, 24 and 72% of that in the control reaction mixture, while higher concentrations of Cd(II) decreased the splicing activity, and more than 50 microM Cd(II) showed a complete absence of spliced products. Hg(II) also restored the splicing activity, albeit to a lesser extent, since 5 and 10 microM Hg(II) restored the splicing activity to 3 and 4% of the control value. The other metal ions examined in this study, Co(II), Cu(II), Mg(II) and Mn(II), did not show any restoration of the splicing activity. We concluded that Cd(II) could restore the in vitro splicing activity inhibited by Zn-depletion, although higher concentrations of Cd(II) prevented progress of the RNA splicing reaction. These results suggest that Cd(II) has a bifunctional property regarding RNA splicing, and is stimulatory at low concentrations and inhibitory at high concentrations.

Animals↗
PubMed2004

Randomized single blind trial of two low-volume bowel preparations for screening computed tomographic colonography.

BACKGROUND: Bowel preparation is an important part of computed tomographic colonography (CTC); we evaluated two small-volume preparations for screening CTC with regard to quality of preparation and patient acceptability. METHODS: Asymptomatic subjects at average risk for colorectal cancer from a community-based CTC screening program were randomized to bowel preparation comprising magnesium/bisacodyl/picolax or polyethylene glycol (PEG)/picolax. CTC images were evaluated by a blinded investigator for residual feces and fluid; subjects completed a questionnaire regarding acceptability of the preparation. RESULTS: In 176 subjects randomized to magnesium/bisacodyl/picolax (n = 82) or PEG/picolax (n = 94), the former preparation was discontinued because of syncope or presyncope in four (5%) subjects. Another 137 subjects received PEG/picolax without a significant adverse event. There were no other major differences in acceptability of the preparations as reported by subjects. The quality of bowel preparations for reporting CTC was similar. CONCLUSION: For subjects having screening CTC, both small-volume bowel preparations are generally well tolerated and result in minimal fluid and fecal residue; however, the magnesium/bisacodyl/picolax preparation was accompanied by an unacceptable incidence of syncope and is no longer used by us.

Bisacodyl↗
PubMed2006

Effect of salt nutrients on mannitol production by Lactobacillus intermedius NRRL B-3693.

The effects of four salt nutrients (ammonium citrate, sodium phosphate, magnesium sulfate, and manganese sulfate) on the production of mannitol by Lactobacillus intermedius NRRL B-3693 in a simplified medium containing 300 g fructose, 5 g soy peptone, and 50 g corn steep liquor per liter in pH-controlled fermentation at 5.0 at 37 degrees C were evaluated using a fractional factorial design. Only manganese sulfate was found to be essential for mannitol production. Added manganese sulfate concentration of 0.033 g/l was found to support maximum production. The bacterium produced 200.6 +/- 0.2 g mannitol, 61.9 +/- 0.1 g lactic acid, and 40.4 +/- 0.3 g acetic acid from 300 g fructose per liter in 67 h.

Biotechnology↗
PubMed1988

Stimulation of the ATP, Mg-dependent protein phosphatase by p-nitrophenyl phosphate.

The phosphorylase phosphatase activity of the ATP,Mg-dependent protein phosphatase is stimulated by p-nitrophenyl phosphate (pNPP). All the active forms of this type of enzyme show this property, which seems to be unrelated to any pNPP-hydrolyzing activity. The increase in activity is due to an increase in Vm, the Km being unchanged. The possibility that pNPP acts as a deinhibitor is excluded. pNPP acts as a competitive inhibitor on the phosphorylase phosphatase activity of the different polycation-stimulated protein phosphatases. Stimulation by pNPP can be used as a differential criterion in a specific assay of the active forms of the ATP,Mg-dependent phosphatase.

Adenosine Triphosphate↗
PubMed1992

The effects of magnesium and fluoride on the hydrolysis of octacalcium phosphate.

The adsorption of Mg ions on octacalcium phosphate (OCP) and its effect on OCP hydrolysis, with and without F, were studied. The Mg adsorption isotherm was fitted by the Langmuir model with an affinity constant of 0.74 ml/mumol and maximum number of sites, 31.19 mumol/g. The hydrolysis rates were measured in a pH stat by titration of base and were strongly temperature dependent. The products were examined by X-ray diffraction and chemical analysis. OCP hydrolysis takes place in two stages: the fast initial process, which is attributed to the surface topotactical conversion, followed by the main, slower process, which involves the nucleation and crystal growth. Mg ions, as 1 mmol/l MgCl2, prevented the initial surface reaction and decreased the nucleation rate dramatically and the growth rate slightly; F increased the rates of surface reaction and both the nucleation and crystal growth processes. The Ca/P ratio (1.53) and the line broadening in the X-ray diffraction patterns of the apatitic products were not significantly affected by the F. Mg also did not affect the Ca/P ratio and the line broadening at (002) diffraction, but decreased the line broadening at (310) diffraction.

Adsorption↗
PubMed1975

Availability of monovalent and divalent cations within intact chloroplasts for the action of ionophores nigericin and A23187.

1. A23187 will uncouple electron transport by broken chloroplasts in a divalent cation dependent manner provided that they have been treated with a low concentration of EDTA. 2. A23187 stimulates oxaloacetate-dependent oxygen evolution and inhibits phosphoglycerate reduction by intact chloroplasts isolated in a cation-free medium whereas the full effect of nigericin was dependent on the presence of external K+. 3. Uncoupling of oxaloacetate reduction by A23187 in intact chloroplasts is inhibited by EDTA and this effect is overcome by excess Mg2+. 4. The results suggest that divalent and not monovalent cations are available for collapsing the light-induced H+ gradient within the intact organelle.

Anti-Bacterial Agents↗