The reaction of guanosine with 3,4-epoxy-1-butene in acetic acid gives two main products of N-7 alkylation. After acidic hydrolysis the two aglycones have been isolated by h.p.l.c. and shown to be ...the regioisomeric 7-(2-hydroxy-3-buten-1-yl) guanine (I) and 7-(1-hydroxy-3-buten-2-yl) guanine (II), arising through nucleophilic attack by N-7 of the purine at the two oxirane carbons of 3,4-epoxy-1-butene. Spectral characteristics of both compounds are presented, including u.v., 1H-n.m.r. and mass spectra. Deoxyguanosine reacts with 3,4-epoxy-1-butene in 50% methanol-water at 37 degrees C to give the N-7 alkylated deoxynucleosides corresponding to I and II in a 59:41 ratio. The reaction rate depends on the nucleoside concentration, with second order rate constants at 37 degrees C of 1.6 X 10(-2) and 1.1 X 10(-2) h-1 M-1 for the formation of the two deoxynucleoside adduct corresponding to I and II, respectively. The same two compounds I and II in a similar (54:46) ratio have been identified after acidic or thermal hydrolysis of DNA which had been reacted with 3,4-epoxy-1-butene under similar conditions. The half life for the spontaneous depurination of I and II in the adducted DNA under physiological conditions (37 degrees C, pH 7.2) is 50 h.
A 65-year-old man with sclerosing mesenteritis developed the nephrotic syndrome. Percutaneous renal biopsy revealed classical histologic findings of minimal change nephropathy with a mild ...interstitial nephritis. Immunomodulation with prednisone led to a rapid and complete remission of the proteinuria but did not alter the course of the underlying sclerosing mesenteritis. The association of lymphomatous and nonlymphomatous neoplasms with minimal change nephropathy has been well-described. Our review of the literature indicates a parallel association of malignant lymphoma with sclerosing mesenteritis and a variety of disorders that constitute a spectrum of disease. The occurrence of this histopathologic form of renal injury and therapeutic response in the setting of a known lymphoreticular disorder suggests a role for a generalized alteration in cell-mediated immunity and not a tumor-induced elaboration of a factor(s) that directly damages the glomerular filtration barrier.
Cassini/VIMS observations of the moon Bellucci, G.; Brown, R.H.; Formisano, V. ...
Advances in space research,
01/2002, Letnik:
30, Številka:
8
Journal Article
Recenzirano
In this paper, we present preliminary scientific results obtained from the analysis of VIMS (Visible and Infrared Mapping Spectrometer) lunar images and spectra. These data were obtained during the ...Cassini Earth flyby in August 1999. Spectral ratios have been produced in order to derive lunar mineralogical maps. Some spectra observed at the north-east lunar limb, show few unusual absorption features located at 0.357, 0.430 and 0.452 μm, the origin of which is presently unknown.
IPSE is a micro-laboratory for Mars soil and environment analysis. It provides the capability to serve and handle scientific miniaturised instruments accommodated inside its envelope. The instruments ...have the goal to perform in situ study of the collected martian samples, thus quantitatively characterizing the mineralogy, the composition, the microphysical structure of the materials of the Martian soils down to the depth available to the sampling mechanism. Given the complex structure of the surface material it will be essential to perform in-situ science, both at the surface and at different depths. This is done in order to validate remote sensing observations through specific measurements, identify local characteristics of the selected landing areas, document sample collection both for in situ and sample return. IPSE is an example of a small and flexible lab, that can be integrated on different Landers and Megarovers. IPSE contains: •Scientific instruments•A small robotic arm - with five degrees of freedom - to provide samples to the IPSE instruments.•Power conditioning.•Electronics for system and thermal control, communications and instrument data handling.
The Phase A report for all the IPSE instruments has been already provided to the Italian Space Agency. The experiments MAGO, IRMA, MA_FLUX are inherited from previous space qualified instruments and breadboards of them already exist. DOSE is a new experiment, however, a breadboard of the detector and of the photomultiplier is under development.
We report on a novel concept of silicon microstrips and straw tubes detector, where integration is accomplished by a straw module with straws not subjected to mechanical tension in a Rohacell/spl ...reg/ lattice and carbon fiber reinforced plastic shell.
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