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121.
Urinary excretion of oxidized nucleobases and nucleosides has been used as a biomarker of oxidative DNA damage and repair. Most studies have focused on the measurements of 8-oxo-7,8-dihydro-2'-deoxyguanosine; however, the urinary levels of other DNA modifications may represent useful indicators of oxidative stress. We developed a method for the determination of 5-hydroxymethyluraciI (5-HMUra), consisting of the separation of the modified base in urine by HPLC and quantification by GC/MS in the selective ion monitoring mode. This experimental approach was subsequently validated in human samples, with the effect of storage and the inter- and intra-individual variations in 5-HMUra excretion being evaluated. Results showed that 5-HMUra is stable in samples frozen at-80 °C for at least 4 months. Inter-individual variations in 5-HMUra excretion were observed when the results were expressed either as nmoles excreted per kg per day (1.2-2.4) or corrected by creatinine values (7.2-12.2 nmoles 5-HMUra per mmoles creatinine). Intra-individual variability was low, varying slightly at different time collections for several individuals. Differences in the excretion of 5-HMUra in urine collected at three different 8-h intervals during the day were not significant and, in particular, the levels of 5-HMUra calculated from the overnight or the 24-h samples were highly correlated. These results indicate that monitoring urinary levels of 5-HMUra could be a suitable indicator of oxidative damage in human studies. 相似文献
122.
Paola Maraschio Rossella Tupler Laura Barbierato Eleonora Dainotti Daniela Larizza Franca Bernardi Heidi Hoeller Angiolina Garau Luciano Tiepolo 《Human genetics》1996,97(3):375-381
We characterized by fluorescence in situ hybridization and Southern blotting 14 partial Xq monosomies, 11 due to terminal deletions and 3 secondary to X/autosome translocations. Three cases were mosaics with a XO cell line. In view of the possible role played by telomeres in chromosome segregation, we hypothesize a relationship between the loss of telomeric sequences in terminal deletions and the presence of 45,X cells. A correlation between phenotype and extent of deletion revealed that there is no correspondence between the size of the deletion and impairment of gonadal function. Turner stigmata are absent in patients without an XO cell line, when the breakpoint is distal to Xg24. A low birthweight is present whenever the breakpoint is at q22 or more proximal. 相似文献
123.
Pierre Leblond Gilles Fischer François-Xavier Francou Franca Berger Michel Guérineau & Bernard Decaris 《Molecular microbiology》1996,19(2):261-271
Physical maps of the chromosomes of three strains of Streptomyces ambofaciens were constructed by ordering Ase I fragments generated from the genomic DNA as a single linear chromosome of about 8 Mb. The physical maps of the three strains were very similar. For strain DSM40697, a Dra I map was obtained by positioning the Dra I sites relative to the Ase I map. Eighteen genetic markers as well as the deletable and amplifiable region were assigned to the Ase I and Dra I fragments in this strain. The resulting genetic map resembled that of Streptomyces coelicolor A3(2). The twoterminal Ase I fragments exhibited retarded pulsed-field gel electrophoresis mobility, demonstrating that proteins are covalently bound at this position. A restriction map of this region was made using four additional endonucleases. Repeated sequences present at both ends of the chromosome were mapped as long terminal inverted repeats stretching over 210 kb. This corresponds to the longest terminal inverted repeats so far characterized. The deletable region of S. ambofaciens was localized at the chromosomal extremities. 相似文献
124.
Giselle Rôças Cláudia Franca Barros Fábio Rubio Scarano 《Trees - Structure and Function》1997,11(8):469-473
Alchornea triplinervia trees occur in a montane Atlantic rainforest at the Macaé de Cima State Ecological Reserve (Nova Friburgo, RJ, Brazil). They
are found in two adjacent secondary forests at distinct successional stages: a late-secondary (shaded and humid) and an early-secondary
forest (drier, higher light intensities reaching the understory). Leaf samples collected in these environments were compared
in regard to various anatomic parameters. Histochemical tests, anatomic measurements and counting indicated no significant
variation for the basic leaf anatomy. Nevertheless, as compared to the late-secondary forest, the leaves of the early-secondary
forest individuals showed an increased bulk of sclerenchyma at the main nervation and petiole, gelatinous fibers with hygroscopic
walls all along the central vascular system, thicker cuticle, a higher abaxial stomatal density, abundance of tannin in the
mesophyll, a significantly thicker palisade and spongy parenchyma, and compactation of the spongy parenchyma. This anatomical
variation indicates an increased xeromorphism of leaves under the drier conditions of the early-secondary forest. Leaf anatomy
plasticity may contribute to the high ecological plasticity of this widespread neotropical species.
Received: 11 November 1996 / Accepted: 5 February 1997 相似文献
125.
Monica Angelini Marta Calbi Annachiara Ferrari Beatrice Sbriscia-Fioretti Michele Franca Vittorio Gallese Maria Alessandra Umiltà 《PloS one》2016,11(3)
Proactive and reactive inhibition are generally intended as mechanisms allowing the withholding or suppression of overt movements. Nonetheless, inhibition could also play a pivotal role during covert actions (i.e., potential motor acts not overtly performed, despite the activation of the motor system), such as Motor Imagery (MI). In a previous EEG study, we analyzed cerebral activities reactively triggered during two cued Go/NoGo tasks, requiring execution or withholding of overt or covert imagined actions, respectively. This study revealed activation of pre-supplementary motor area (pre-SMA) and right inferior frontal gyrus (rIFG), key nodes of the network underpinning reactive inhibition of overt responses in NoGo trials, also during MI enactment, enabling the covert nature of the imagined motor response. Taking into account possible proactive engagement of inhibitory mechanisms by cue signals, for an exhaustive interpretation of these previous findings in the present study we analyzed EEG activities elicited during the preparatory phase of our cued overt and covert Go/NoGo tasks. Our results demonstrate a substantial overlap of cerebral areas activated during proactive recruitment and subsequent reactive implementation of motor inhibition in both overt and covert actions; also, different involvement of pre-SMA and rIFG emerged, in accord with the intended type (covert or overt) of incoming motor responses. During preparation of the overt Go/NoGo task, the cue is encoded in a pragmatic mode, as it primes the possible overt motor response programs in motor and premotor cortex and, through preactivation of a pre-SMA-related decisional mechanism, it triggers a parallel preparation for successful response selection and/or inhibition during the response phase. Conversely, the preparatory strategy for the covert Go/NoGo task is centered on priming of an inhibitory mechanism in rIFG, tuned to the instructed covert modality of motor performance and instantiated during subsequent MI, which allows the imagined response to remain a potential motor act. 相似文献
126.
Astréa M. Giesbrecht Nídia C. Franca Otto R. Gottlieb Arnaldo I. Da Rocha 《Phytochemistry》1974,13(10):2285-2293
The trunk wood of Licaria canella contains, besides dillapiol and elemicin, the neolignans canellin-A, -B and -C, for which the respective structures of 1-allyl-4,8-dihydroxy-3,5-dimethoxy-7-methyl-6-piperonylbicyclo-[3,2,1]octane; 3a-allyl-4,5-dimethoxy-3-methyl-2-piperonyl-2,3,3a,6,7,7a-hexahydro-6-oxobenzofuran and 1-allyl-4,8-dihydroxy-5-methoxy-7-methyl-6-piperonyl-3-oxobicyclo-[3,2,1] octane are proposed. 相似文献
127.
Paolo Parenti Franca V. Sacchi Giorgio M. Hanozet Barbara Giordana 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1986,156(4):549-556
Summary A net absorption of sodium ions and ofl-phenylalanine, in the absence of chemical gradients, occurs across the isolated midgut of the cockroachBlabera gigantea. Both sodium and amino acid net fluxes were abolished by the haemolymphatic addition of the Na–K ATPase inhibitor ouabain, at a concentration 1 mM. A purified fraction of brush border membranes, prepared from the midgut tissue by Ca-precipitation, was used to investigate the occurrence of a cotransport system in the luminal membrane of the cockroach enterocyte. An inwardly directed Na gradient (100 mM outside the vesicles, 0 mM inside) drives the uphill movement of phenylalanine into the vesicular space, whilst other monovalent cations fail to induce the concentrative uptake of the amino acid. Moreover, the amino acid uptake seems to be dependent on the transmembrane potential, since inwardly directed gradients of different sodium salts determine a decreasing rate of phenylalanine uptake in agreement with the presumptive permeabilities of Na counterions. These data suggest the presence of a Na-phenylalanine cotransport system located on the brush border membrane ofB. gigantea midgut.Abbreviations
BBMV
brush border membrane vesicles
-
HEPES
N-2-hydroxyethyl-piperazine-N-2-ethanesulfonic acid
-
PD
transepithelial electrical potential difference
-
TMA
tetramethylammonium
-
Tris
tris-(hydroxymethyl) aminomethane 相似文献
128.
G. Simoni G. Gimelli Cristina Cuoco Lorenza Romitti G. Terzoli Silvana Guerneri Franca Rossella Luisa Pescetto Annalisa Pezzolo Simona Porta B. Brambati E. Porro M. Fraccaro 《Human genetics》1986,72(3):203-209
Summary Cytogenetic investigations for diagnostic purposes were performed on 1000 first trimester samples of chorionic villi (CVS) in two laboratories using similar techniques. Fetal karyotyping was the primary indication for CVS in 912 and maternal age was the major indication in 758 of them. The risk category previous child/fetus with chromosome abnormality included 74 diagnoses, while the category chromosome abnormality in one of the parents included 38 diagnoses. Sex determination was the primary indication for CVS in 53 pregnancies. The overall incidence of chromosomal abnormalities was 70, of which 47 were balanced and 23 unbalanced. The results are detailed for each of the risk categories and the incidence of abnormal karyotypes is given for each year of maternal age. In the maternal age of 35–37 years the incidence of unbalanced karyotypes was 2.9% and in the years 38 onwards it was 6.6%. The incidence of unbalanced karyotypes was about 4% when the sampling was made in the weeks 9 to 12 but six abnormal karyotypes were found among 39 CVS performed at the eight week of gestation. The 11 trisomies of the type not found at birth were clustered between the 8th and the 10th week of pregnancy. The technical problems encountered in this experience and the preliminary estimates of fetal loss are discussed. 相似文献
129.
Cyclization of squalene-2,3-epoxide to 10α-cucurbita-5,24-dien-3β-ol by microsomes from Cucurbita maxima seedlings 总被引:1,自引:0,他引:1
Gianni Balliano Otto Caputo Franca Viola Laura Delprino Luigi Cattel 《Phytochemistry》1983,22(4):915-921
Labelled 10α-cucurbita-5,24-dien-3β-ol was obtained from [3-3H]squalene-2,3-epoxide incubated with microsomes of Cucurbita maxima seedlings. By contrast the lanostane triterpenoids [2-3H]cycloartenol, [2-3H]parkeol and their corresponding derivatives [2,12-3H]11-ketocycloartenol and [2-3H]24,25-dihydro-90α,11a-epoxyparkeol, incubated under the same conditions, gave no rearranged products with a cucurbitane skeleton. These results suggest that biosynthesis of cucurbitane triterpenoids from squalene-2,3-epoxide occurs through direct cyclization without the intermediacy of lanostane-type triterpenoids such as cycloartenol or parkeol. Labelled cycloartenol, α-amyrin, β-amyrin and 24-methylenecycloartanol were also obtained from [3-3H]squalene-2,3-epoxide in the same enzymatic system yielding labelled 10α-cucurbitadienol. 相似文献
130.
Complex-type glycopeptides from Human Tamm-Horsfall glycoprotein were fractionated by affinity chromatography on leucoagglutinin-agarose. An oligosaccharide species was retained by the lectin-gel, suggesting that it contains an -mannose residue of the trimannosyl core substituted at C-2 and C-6 positions with -N-acetylglucosamine, as in tetraantennary oligosaccharides. The carbohydrate composition supported this branching pattern. The agglutination of neuraminidase-treated human erythrocytes induced by leucoagglutinin was selectively inhibited by the tetraantennary glycopeptide fraction. 相似文献