Estrogen fluoroimmunoassay with a fluorimeter designed for low-intensity light detection

A small, highly sensitive, inexpensive fluorimeter for the detection of very low fluorescence intensities for analytical and clinical purposes is described. High sensitivity is achieved by use of an inexpensive continuous wave laser with a power of a few milliwatts. The optical arrangement of the instrument has been thoroughly designed so that the effects of Rayleigh and Raman scattering are minimized. Fluorescence is dected through optical filters with a side-on photomultiplier. Concentrations of rhodamine B in ethanol as low as 10^?11 M can be measured. To use this instrument for a fluoroimmunoassay of urinary estrogens (10^?9?10^?7 M), a purified monoclonal IgG, raised against estradiol, was labelled with RITC (rhodamine isothiocyanate) in a 1:1 molar ratio. It was possible to measure IgG-RITC concentrations between 10^?9 and 10^?10 M with good accuracy and reproducibility.     

In Silico Investigation of the Biological Implications of Complex DNA Damage with Emphasis in Cancer Radiotherapy through a Systems Biology Approach

Different types of DNA lesions forming in close vicinity, create clusters of damaged sites termed as “clustered/complex DNA damage” and they are considered to be a major challenge for DNA repair mechanisms resulting in significant repair delays and induction of genomic instability. Upon detection of DNA damage, the corresponding DNA damage response and repair (DDR/R) mechanisms are activated. The inability of cells to process clustered DNA lesions efficiently has a great impact on the normal function and survival of cells. If complex lesions are left unrepaired or misrepaired, they can lead to mutations and if persistent, they may lead to apoptotic cell death. In this in silico study, and through rigorous data mining, we have identified human genes that are activated upon complex DNA damage induction like in the case of ionizing radiation (IR) and beyond the standard DNA repair pathways, and are also involved in cancer pathways, by employing stringent bioinformatics and systems biology methodologies. Given that IR can cause repair resistant lesions within a short DNA segment (a few nm), thereby augmenting the hazardous and toxic effects of radiation, we also investigated the possible implication of the most biologically important of those genes in comorbid non-neoplastic diseases through network integration, as well as their potential for predicting survival in cancer patients.     

Structural investigation of a new variety of the low dimensional conductor with 2 m = 5 + 5: P 4 W 10 O 38

A new variety of P ₄ W ₁₀ O ₃₈ , m = 5 member of the monophosphate tungsten-bronze family with pentagonal tunnels (MPTB p), , has been isolated and studied by X-ray diffraction measurements. The structure has been solved by direct methods from single crystal X-ray data. The monoclinic unit cell corresponds to a regular stacking of WO ₃ -type slabs which are all five-WO ₆ -octahedra thick and connected through PO ₄ tetrahedra. This structure is comparable to that previously described for the MPTB p'series with m = 4 (P ₄ W ₈ O ₃₂ ) and m = 6 (P ₄ W ₁₂ O ₄₄ ). An X-ray diffuse scattering investigation has revealed that this member is subjected to charge density wave instabilities (CDW) located on chains running along the directions. Two CDW transitions have been observed at and , bearing some resemblance with those exhibited by the m = 4 member. The corresponding modulation wave vectors can be accounted for by a hidden nesting mechanism which connects the crossing points of differently oriented quasi-planar Fermi surfaces, as found for the low m (4 and 6) members of the MPTB's. Received 12 March 1999 and received in final form 20 May 1999     

Lignans and neolignans from Myristica argentea Warb

The petrol extract from mace of Myristica argentea Warb. afforded six phenylpropenes, three lignans, three neolignans and a dilignan, bis erythro-argenteane (4) or rel-(8R,8'S,8"S,8"'R)-5',5"'-bis(7-(3,4-methylenedioxyphenyl)-7'-(4'-hydroxy-3'-methoxyphenyl)-8.8'-lignane]. The last-named compound is a new natural product.     

Ab initio fermi surface calculation for charge-density wave instability in transition metal oxide bronzes

The electronic structure of the charge density wave (CDW) bronze (PO2)(4)(WO3)(2m), m = 4, is determined using ab initio density functional theory. The calculation shows that the Fermi surface (FS) consists in the superposition of three one-dimensional FS's associated with three types of chains. The q dependence of the electronic response function calculated from the electronic structure quantitatively accounts for the anisotropy of the fluctuations probed by x-ray diffuse scattering. The results validate the hidden nesting mechanism proposed for the CDW transitions in this series of bronzes.     

Chiral Anthranyl Trifluoromethyl Alcohols: Structures,Oxidative Dearomatization and Chiroptical Properties

Chiral trifluoromethyl alcohol groups were introduced at the hindered ortho positions of 9,10-diphenylanthracenes to investigate their effects on the physical properties and reactivity towards oxidative dearomatization. In such compact structures, the position in different quadrants and the preferred orientation of the −CH(OH)CF₃ groups were determined by the relative and absolute configurations of each stereoisomer, respectively. As a consequence, the stereochemistry governs the organization of the H-bonded molecules in single crystals (homochiral dimers vs ribbon), whereas in chlorinated solvents, they all behave as discrete compounds. Concerning their reactivity, the stereospecific dearomative oxidation of these molecules leads to 9,10-bis-spiro-isobenzofuran-anthracenes, when using organic single-electron transfer oxidants. The chiroptical properties of the alcohols and the corresponding dearomatized products were compared and showed an important modulation of the intensity.