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41.
Maura Turriani Rossana Pesi Antonella Nardone Gino Turchi Francesco Sgarrella Pier Luigi Ipata Maria Grazia Tozzi 《Journal of biochemical and molecular toxicology》1994,9(1):51-57
Nucleoside phosphotransferase acting on inosine and deoxyinosine has been partially purified from cultured Chinese hamster lung fibroblasts (V79). The activity is associated with a cytosolic 5′-nucleotidase acting on IMP and deoxyIMP. The transfer of the phosphate group from IMP to inosine catalyzed by this enzyme was activated by ATP and 2,3-bisphosphoglycerate. Inosine, deoxyinosine, guanosine, deoxyguanosine, and the nucleoside analogs 2′,3′-dideoxyinosine and 8-azaguanosine are substrates, while adenosine and deoxyadenosine are not. IMP, deoxyIMP, GMP, and deoxyGMP are the best phosphate donors. The cytosolic 5′-nucleotidase/phosphotransferase substrate, 8-azaguanosine, was found to be very toxic for cultured fibroblasts (LD50 = 0.32 μM). Mutants resistant to either 8-azaguanosine and the correspondent base 8-azaguanine were isolated and characterized. Our results indicated that the 8-azaguanosine-resistant cells were lacking both cytosolic 5′-nucleotidase and hypoxanthine-guanine phosphoribosyltransferase, while 8-azaguanine resistant cells were lacking only the latter enzyme. Despite this observation, both mutants displayed 8-azaguanosine resistance, thus indicating that cytosolic 5′-nucleotidase is not essential for the activation of this nucleoside analog. 相似文献
42.
Luigi Bosco Cristiana Valle Daniela Willems 《Development, growth & differentiation》1993,35(3):257-270
After lentectomy of larval Xenopus laevis , the outer cornea undergoes tissue transformation resulting in formation of a new lens. This lens regeneration is triggered and sustained by neural retina. In the present study, lens-forming transformation of the outer cornea was completed in vitro when the outer cornea was cultured within the lentectomized eye-cup. Well-differentiated lens fiber cells, which showed positive immunofluorescence for total crystallins, were also formed when the outer cornea was cultivated with the retina. No lens tissue was formed when the cornea was cultured alone. Lens-forming transformation, originating from the cornea three and five days after lentectomy, completely regressed when the tissue was isolated in vitro . Fom the present and previous findings, we concluded that, the interaction of corneal cells with the retina plays a decisive role in lens regeneration in situ . 相似文献
43.
44.
Kay Huebner Teresa Druck Sal LaForgia Jerzy Lasota Carlo M. Croce Luisa Lanfrancone Emilio Donti Gina Pengue Girolama La Mantia Pier-Giuseppe Pelicci Luigi Lania 《Human genetics》1993,91(3):217-222
cDNA clones encoding zinc finger motifs were isolated by screening human placenta and T-cell (Peer) cDNA libraries with zinc finger (ZNF) consensus sequences. Unique cDNA clones were mapped in the human genome by rodent-human somatic cell hybrid analysis and in some cases in situ chromosomal hybridization. ZNF 80 mapped to 3p12-3qter, ZNF 7 was previously mapped to 8q24 and is here shown by in situ hybridization and use of appropriate hybrids to map telomeric to the MYC locus. ZNF 79 mapped to 9q34 centromeric to the ABL gene and between a constitutional chromosomal translocation on the centromeric side and the CML specific ABL translocation on the telomeric side. ZNF77 mapped to 19p while ZNF 78L1 (pT3) mapped to 19q. Chromosome 19 carries many ZNF loci and other genes with zinc finger encoding motifs; the pT3 clone additionally detected a locus designated ZNF 78L2, which mapped to chromosome region 1p, most likely in the region 1p32 where the MYCL and JUN loci map. 相似文献
45.
Maura Francolini Marialuisa Lavitrano Carla Lora Lamia Deborah French Luigi Frati Franco Cotelli Corrado Spadafora 《Molecular reproduction and development》1993,34(2):133-139
Mature sperm cells have the spontaneous capacity to take up exogenous DNA. Such DNA specifically interacts with the subacrosomal segment of the sperm head corresponding to the nuclear area. Part of the sperm-bound foreign DNA is further internalized into nuclei. Using end-labelled plasmid DNA we have found that 15–22% of the total sperm bound DNA is associated with nuclei as determined on isolated nuclei. On the basis of autoradiographic analysis, nuclear permeability to exogenous DNA seems to be a wide phenomenon involving the majority of the sperm nuclei. In fact, the foreign DNA, incubated with sperm cells for different lengths of time, is found in 45% (10 min) to 65% (2 hr) of the sperm nuclei. Ultrastructural autoradiography on thin sections of mammalian spermatozoa, preincubated with end-labelled plasmid DNA, shows that the exogenous DNA is internalized into the nucleus. This conclusion is further supported by ultrastructural autoradiographic analysis on thin sections of nuclei isolated from spermatozoa preincubated with end-labelled DNA. © 1993 Wiley-Liss, Inc. 相似文献
46.
Xu Yuping Wang Lu Tang Quehui Naselli-Flores Luigi Jeppesen Erik Han Bo-Ping 《Ecosystems》2023,26(4):752-767
Ecosystems - The relationship between species diversity and ecosystem functioning is one of central topics in modern ecology, but variable and controversial patterns have been found depending on... 相似文献
47.
Raffaello Romeo Giuseppe Arena Luigi Mons Scolaro Maria Rosario Plutino 《Inorganica chimica acta》1995,240(1-2):81-92
The rates of displacement of dimethyl sulfoxide from the cation [Pt(phen) (CH3) (Me2SO)]+ by a series of uncharged and negatively charged nucleophiles have been measured in a methanol/water (19:1 vol./vol.) mixture. The starting complex and the reaction products were characterized either as solids or in solution by their IR and 1H NMR spectra. The substitution reactions take place by way of a direct bimolecular attack of the ligand on the substrate. The sequence of reactivity observed is as expected on the basis of a nucleophilicity scale relevant for + 1 charged substrates ([Pt(en) (NH3)Cl]+ used as standard). The difference of reactivity between the first (t-BuNH2) and the last (SeCN−) members of the series spans five orders of magnitude. The value measured for the nucleophilic discrimination (1.55) is the highest found so far for cationic substrates. This is a result of the easy transfer of some of the electron density brought in by the incoming ligand into the ancillary ligands. When the reaction is carried out in a series of protic and dipolar aprotic solvents, using chloride ion as nucleophile, the rate of formation of [Pt (phen) (CH3)Cl] is dominated by the extent of solvation of Cl−, as measured by its values of the Gibbs molar energy of transfer ΔtG0. Conductivity measurements at 25°C in dichloromethane were fitted to the Fuoss equation and the values of the dissociation constants Kd for the ion pairs were calculated as follows: 2.27 × 10−5 M for Bu4NCl, 2.75 × 10−5 M for Bu4NSCN and 17.05 × 10−5 M for [Pt(phen) (CH3) (Me2SO)]PF6. The pseudo-first-order rate constants kobs for the reactions with Bu4NCl, Bu4NBr, Bu4NSCN and Bu4NI showed a curvilinear dependence on the concentration of the salt which levels off very soon (at concentrations higher than 0.005 M the kinetics are zero order in [Bu4NX]). On addition of the inert electrolyte Bu4NPF6 the rates slow down and the kinetics follow the rate law kobs = kKip[Bu4NX]/[Bu4NPF6] + Kip[Bu4NX]). These findings fit well with a reaction scheme which involves a pre-equilibrium Kip between ion pairs, followed by unimolecular substitution within the contact ion pair [Pt(phen) (CH3) (Me2SO)X]ip. Values of the equilibrium constants Kip for ion-pair exchange and of the internal substitution rates k were derived. The latter showed that the discrimination in reactivity between Cl−, Br−, SCN− and I− is greatly reduced with respect to aqueous solutions. The reason behind this may be desolvation of the ions coupled to the fact that a contact ion pair is already at a certain distance along the reaction coordinate in the direction of the transition state. Applications of the special salt effect and of ion pairing to synthesis are discussed. 相似文献
48.
Oliver Renn Heinz Rüegger Luigi M. Venanzi Jürgen Gallus Volker Gramlich Arianna Martelletti 《Inorganica chimica acta》1995,240(1-2):575-580
It is shown that the reaction of RhCl3·3H2O with acetonitrile normally produces mixtures of mer- and fac-[RhCl3(CH3CN)3] (1a and 1b, respectively). The IR and 1H NMR spectra of these isomers were re-investigated. Their two-dimensional (103Rh,1H) NMR spectra were also recorded. Equilibrium and exchange studies of 1a and 1b in CD3C were performed. It was found that in 1a the exchange rate of the nitrile molecule trans to Cl is much faster than those of mutually trans nitriles. Also the nitrile molecules in 1b underwent fast exchange in CD3CN; however, their rate was slightly faster than that of the more labile CH3CN in 1a. The X-ray crystal structure of mer-[RhCl3(CH3CN)3]·CH3CN (1c) was determined. Crystal data: triclinic space group . 相似文献
49.
Luigi A. M. Castagnetta Orazia M. Granata Vincenzo Bellavia Rosalba Amodio Eugenia Scaccianoce Monica Notarbartolo Maria R. Follari M. Dora Miceli Giuseppe Carruba 《The Journal of steroid biochemistry and molecular biology》1997,61(3-6):287-292
We investigated conversion rates of androgens to estrogens in cultured, hormone-responsive prostate (LNCaP) and breast (MCF-7) human cancer cells. For this purpose, we adopted an intact cell analysis, whereby cells were incubated for different incubation times in the presence of close-to-physiological (1 nM) or supraphysiological (1 μM) concentrations of labelled androgen precursors, i.e. testosterone (T) and androstenedione (Δ4Ad). The aromatase activity, as measured by estrogen formation, was detected in LNCaP cells (0.5 pmol/ml), even though to a significantly lower extent than in MCF-7 cells (5.4 pmol/ml), using 1 μM T after 72 h incubation. Surprisingly, LNCaP cells displayed a much higher aromatase activity when T was used as a substrate with respect to Δ4Ad. In either cell line, T transformation to Δ4Ad was relatively low, attaining only 2.8% in LNCaP and 7.5% MCF-7 cells. However, T was mostly converted to conjugates (over 95%), glucuronides and some sulphates, in LNCaP cells, whereas it was only partly converted to sulphates (<10%) in MCF-7 cells. Aromatase activity seems to be inconsistent in LNCaP cells, being strongly affected by culture conditions, especially by fetal calf serum (FCS). Further studies should assess the regulation of aromatase expression by serum or growth factors in different human cancer cells, also using anti-aromatase and/or anti-estrogen compounds, in different culture conditions. 相似文献
50.
Adobati Elena; Panza Luigi; Russo Giovanni; Colnaghi Maria I.; Canevari Silvana 《Glycobiology》1997,7(2):173-178
The murine monoclonal antibody (Mab) MBr1, raised against thebreast cancer cell line MCF7, recognizes a saccharidic epitopeoverexpressed on a high percentage of human breast, ovary, andlung carcinomas. This antigen was originally identified on theimmunogen as a globo-series glycosphingolipid with an H-likedeterminant at its terminus (globo-H). We report here the biologicalcharacterization of the entire globo-H hexasaccharide and fivesynthetic oligosaccharides representing fragments of the entirestructure andlor different anomeric configurations. Using competitivebinding assays on live cells, we identified the residues andthe linkages essential for mimicry of the cellular antigensrecognized by Mab MBr1 on the breast carcinoma cell line MCF7and small cell lung cancer cell line POVD. The terminal tetrasaccharidicfragment of globo-H is the oligosaccharide that most resemblesthe MBr1-defined epitope both on glycolipids and on glycoproteins.This information will help in the rational design of a highlyspecific reagent for active specific immunotherapy of carcinomasoverexpressing the MBr1-defined antigen. CaMBr1 immunotherapy monoclonal antibody oligosaccharides tumor-associated antigen 相似文献