90 research outputs found
Theoretical Design of a New Allosteric Switch and Fluorescence Chemosensor Double Functional Devices of Aza-Crown Ether
A novel molecular device (<i>trans</i>-azobenzene embedded <i>N</i>-(11-pyrenyl methyl)Âaza-21-<i>crown</i>-7) with
double functional devices was designed on the basis of theoretical
calculations. Pyrenyl methyl covalently bonded to aza-21-<i>crown</i>-7 at the nitrogen position interacting with a series of alkaline-earth
metal cations (Mg<sup>2+</sup>, Ca<sup>2+</sup>, Sr<sup>2+</sup>,
and Ba<sup>2+</sup>) was investigated. The fully optimized geometries
and real frequency calculations were investigated using a computational
strategy based on density functional theory at B3LYP/6-31GÂ(d) level.
Free ligand (<b>L</b>) and their metal cation complexes (<b>L</b>/M<sup>2+</sup>) were studied using mixed basis set (6-31GÂ(d)
for the atoms C, H, O, and N and LANL2DZ for alkaline-earth metal
cations Mg<sup>2+</sup>, Ca<sup>2+</sup>, Sr<sup>2+</sup>, and Ba<sup>2+</sup>. The natural bond orbital analysis that is based on optimized
geometric structures was used to explore the interaction of <b>L</b>/M<sup>2+</sup> molecules. The absorption spectra of <b>L</b> and <b>L</b>/M<sup>2+</sup>, excitation energies,
and absorption wavelength for their excited states were studied by
time-dependent density functional theory with 6-31GÂ(d) and LANL2DZ.
A new type of molecular device is found, which has the selectivity
to Ca<sup>2+</sup> and the emission fluorescence of <b>L</b>/Ca<sup>2+</sup> under the condition of illumination. This molecular
device would serve as an allosteric switch and a fluorescence chemosensor
Uptake and Accumulation of Nephrotoxic and Carcinogenic Aristolochic Acids in Food Crops Grown in Aristolochia clematitis-Contaminated Soil and Water
Emerging
evidence has suggested aristolochic acids (AAs) are linked
to the development of Balkan endemic nephropathy (BEN), a chronic
renal disease affecting numerous farmers living in the Balkan peninsula.
However, the pathway by which AAs enter the human food chain and cause
kidney disease remains poorly understood. Using our previously developed
analytical method with high sensitivity and selectivity (Chan, W.;
Lee, K. C.; Liu, N.; Cai, Z. <i>J. Chromatogr. A</i> <b>2007</b>, <i>1164</i>, 113–119), we quantified
AAs in lettuce, tomato, and spring onion grown in AA-contaminated
soil and culture medium. Our study revealed that AAs were being taken
up from the soil and bioaccumulated in food crops in a time- and dose-dependent
manner. To the best of our knowledge, this study is the first to identify
one of the possible pathways by which AAs enter our food chain to
cause chronic food poisoning. Results also demonstrated that AAs were
resistant to the microbial activity of the soil/water
Rate-Limiting Nutrient Delivery System for Microbial Enhanced Oil Recovery
A limitation of biostimulation for microbial enhanced oil recovery and in situ bioremediation is loss of injectivity that can be encountered when microorganisms grow in the high nutrient concentrations found near the injection well. By encapsulating rate-limiting nutrients, it is hoped that they can be delivered to the target zone without causing near-wellbore biofouling.<br><br>Poster presented at 6<sup>th</sup> Annual Graduate Research Poster
Competition, University of Kansas School of Engineering, Lawrence, KS. 11 April
2013.<b><br><br></b><br><br><br><br
Quantification of DNA and Protein Adducts of 1‑Nitropyrene: Significantly Higher Levels of Protein than DNA Adducts in the Internal Organs of 1‑Nitropyrene Exposed Rats
1-Nitropyrene (1NP)
level is closely associated with the mutagenicity
of diesel exhaust and is being used as the marker molecule for diesel
exhaust. Thus, quantitation of the exposure to 1NP may provide an
efficient method for biomonitoring human exposure to diesel exhaust
and risk assessment. Using ultra-performance liquid chromatography
coupled with fluorescence or tandem mass spectrometric detection methods,
we quantitated and compared in this study the DNA and protein adducts
of 1NP in internal organs of 1NP-exposed rats. While previous studies
using radioactivity-based detection methods were descriptive in nature
and focused on the mutation-associated genetic materials, the results
of our quantitative analysis showed, for the first time, a significantly
higher concentration of the protein adduct than the DNA adduct in
the tissue samples. The data also revealed higher in vivo stability
of the protein adduct than that of the DNA adduct. Our results provide
solid evidence that demonstrates that the protein adduct might be
a more-sensitive dosimeter for 1-NP and, thus, diesel-exhaust exposure
The Epidemiology of Critique
<p>Measurement results of the straight-line distance at the X-axis (unit: mm).</p
Determination of fitting method center points.
<p>Determination of fitting method center points.</p
Measurement results of the straight-line distance at the Z-axis (unit: mm).
<p>Measurement results of the straight-line distance at the Z-axis (unit: mm).</p
Determination of contact method center points.
<p>Determination of contact method center points.</p
Registration of mark points for upper and lower edentulous jaw models and dentures using the RPS registration command.
<p>Registration of mark points for upper and lower edentulous jaw models and dentures using the RPS registration command.</p
Lysine Adduction by Reactive Metabolite(s) of Monocrotaline
Pyrrolizidine
alkaloids (PAs) are known hepatotoxins. The execution of the toxicities
of the alkaloids requires metabolic activation. Protein modification
by reactive metabolites of PAs has been suggested to be an important
mechanism of the toxic actions of PAs. The objectives of the present
study were to define the interactions of dehydromonocrotaline (DHM)
with lysine, lysine derivatives, a model peptide, and bovine serum
albumin and to explore the lysine modification of hepatic proteins
of animals given monocrotaline. DHM was found to react with the ε-amino
group of all model compounds tested after incubation with DHM, and
the modification reaction preferentially occurred at C<sub>7</sub> of the necine base. The lysine residue modification with the same
regioselectivity was also observed in hepatic proteins of mice treated
with monocrotaline. The observed modification increased with the increase
in doses administered to the animals. This work allowed us to better
understand the mechanisms of the hepatotoxicity of monocrotaline
- …