Comparison of figures of merit for fluorimetric analysis of rhodamine complexes of gallium and indium by excitation with pulsed laser and by xenon arc sources

Optimum conditions have been established for formation and extraction of indium-Rhodamine complexes, and limits of detection found for fluorimetric determination of gallium and indium by means of Rhodamine dyes, using the excitation with pulsed laser and xenon arc sources.     

Direct observation of eta 2-imine formation through beta-H abstraction between amide ligands. Neutron and X-ray diffraction structure of a dihydride imine ditantalum complex

Reactions of Ta(NMe2)5 with D2SiR'Ph (R' = Me, Ph) were found to give a dideuteride eta 2-imine complex (Me2N)3Ta(mu-D)2(mu-N-eta 2-N,C-CH2NMe)Ta(NMe2)3(1-d2) through C-H activation of an amide ligand via beta-H abstraction, and the structure of 1 was confirmed by single crystal neutron and X-ray diffraction.     

Simultaneous determination of noradrenaline and dopamine in Portulaca oleracea L. by capillary zone electrophoresis

A simple and rapid capillary electrophoretic method was developed for the simultaneous determination of noradrenaline (NA) and dopamine (DA) in Portulaca oleracea L. The buffer solution used in this method was 40 mM tris (hydroxymethyl) aminomethane (Tris)-H3PO4 at pH 2.00 containing 15% methanol. The effects of pH value, organic modifier, and applied voltage were investigated. The linear ranges of NA and DA were 0.5-100 microg/mL (r=0.9952) and 6.25-200 microg/mL (r=0.9992), respectively. The relative standard deviations of the corrected peak area were 6.73% and 4.26%, respectively. NA and DA in Portulaca oleracea L. were simultaneous determined successfully within 5.6 min. In this way, the contents of NA and DA in different parts (stem, leaves, and seeds) of P. oleracea L. and in different extracts of leaves with different solvents (distilled water, 50% methanol, and methanol) were studied.     

Quantitation of the global secondary structure of globular proteins by FTIR spectroscopy: Comparison with X-ray crystallographic structure

Fourier transform infrared spectroscopy (FTIR) is potentially a powerful tool for determining the global secondary structure of proteins in solution, providing the spectra are analyzed using a statistically and theoretically justified methodology. We have performed FTIR experiments on 14 globular proteins and two synthetic polypeptides whose X-ray crystal structures are known to exhibit varying types and amounts of secondary structures. Calculation of the component structural elements of the vibrational bands was accomplished using nonlinear regression analysis, by fitting both the amide I and amide II bands of the Fourier self-deconvoluted spectra, the second-derivative spectra, and the original spectra. The methodology was theoretically justified by comparing (via nonlinear regression analysis) the global secondary structure determined after deconvolving into component bands the vibrational amide I envelopes with the calculated structure determined by first principles from Ramachandran analysis of the X-ray crystallographic structure of 14 proteins from the Brookhaven protein data bank. Justification of the nonlinear regression analysis model with respect to experimental and instrumental considerations was achieved by the decomposition of all the bands of benzene and an aqueous solution of ammonium acetate into component bands while floating the Gaussian/Lorentzian character of the line shapes. The results for benzene yield all pure Lorentzian line shapes with no Gaussian character while the ammonium acetate spectra yielded all Gaussian line shapes with no Lorentzian character. In addition, all-protein spectra yielded pure Gaussian line shapes with no Lorentzian character. Finally, the model was statistically justified by recognizing random deviation patterns in the regression analysis from all fits and by the extra sum of squares F-test which uses the degrees of freedom and the root mean square values as a tool to determine the optimum number of component bands required for the nonlinear regression analysis. Results from this study demonstrate that the globular secondary structure calculated from the amide I envelope for these 14 proteins from FTIR is in excellent agreement with the values calculated from the X-ray crystallographic data using three-dimensional Ramachandran analysis, providing that the proper contribution from GLN and ASN side chains to the 1667 and 1650 cm(-1) component bands has been taken into account. The standard deviation of the regression analysis for the per cent helix, extended, turn and irregular conformations was found to be 3.49%, 2.07%, 3.59% and 3.20%, respectively.     

Discrimination of basal cell carcinoma from normal dermal stroma by quantitative multiphoton imaging

We performed multiphoton fluorescence (MF) and second-harmonic generation (SHG) imaging on human basal cell carcinoma samples. In the dermis, basal cell carcinomas can be identified by masses of autofluorescent cells with relatively large nuclei and marked peripheral palisading. In the normal dermis, SHG from dermal collagen contributes largely to the multiphoton signal. However, within the cancer stroma, SHG signals diminish and are replaced by autofluorescent signals, indicating that normal collagen structures responsible for SHG have been altered. To better delineate the cancer cells and cancer stroma from the normal dermis, a quantitative MF to SHG index is developed. We demonstrate that this index can be used to differentiate cancer cells and adjacent cancer stroma from the normal dermis. Our work shows that MF and SHG imaging can be an alternative for Mohs' surgery in the real-time guidance of the secure removal of basal cell carcinoma.