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排序方式: 共有197条查询结果,搜索用时 31 毫秒
1.
Twenty-nine adult patients with primary myelodysplastic syndromes (MDS) and an excess of marrow blasts were treated by aggressive chemotherapy while still in MDS phase (20 cases) or after progression to ANLL (9 cases). Median age was 47.5 (range 18-68). Twenty-eight patients received a combination of Rubidazone and Ara C and 1 received High dose Ara C. Fourteen patients (48%) achieved complete remission (CR), 5 (17%) were treatment failures (F) and 10 (35%) died during therapy induced aplasia (DA). Median disease free survival was 8.5 months. Median survival of the whole population was 6 months from the onset of treatment, and 17 months in patients achieving CR. These results were significantly less favorable than those obtained at our institution in de novo ANLL with the same chemotherapy regimens. No statistically significant prognostic factors of treatment outcome emerged but patients with normal cytogenetic findings seemed to have both a higher CR rate and longer remissions than patients with abnormal karyotypes. Patients under 50 did not have higher CR rates than older patients, although they had longer remissions (with 3 out of 6 CRs exceeding 2 years). Finally, treatment outcome and survival were identical in patients treated in the MDS phase and in those treated after progression to ANLL. Combination chemotherapy is a highly toxic approach in MDS and essentially seems to benefit younger patients with a normal karyotype, in whom some long remissions can be obtained. 相似文献
2.
The mechanism of insulin stimulation of (Na+,K+)-ATPase transport activity in muscle 总被引:8,自引:0,他引:8
Since the mechanism underlying the insulin stimulation of (Na+,K+)-ATPase transport activity observed in multiple tissues has remained undetermined, we have examined (Na+,K+)-ATPase transport activity (ouabain-sensitive 86Rb+ uptake) and Na+/H+ exchange transport (amiloride-sensitive 22Na+ influx) in differentiated BC3H-1 cultured myocytes as a model of insulin action in muscle. The active uptake of 86Rb+ was sensitive to physiological insulin concentrations (1 nM), yielding a maximum increase of 60% without any change in 86Rb+ permeability. In order to determine the mechanism of insulin stimulation of (Na+,K+)-ATPase activity, we demonstrated that insulin also stimulates passive 22Na+ influx by Na+/H+ exchange transport (maximal 200% increase) and an 80% increase in intracellular Na+ concentration with an identical time course and dose-response curve as insulin-stimulated (Na+,K+)-ATPase transport activity. Incubation of the cells with high [Na+] (195 mM) significantly potentiated insulin stimulation of ouabain-inhibitable 86Rb+ uptake. The ionophore monensin, which also promotes passive Na+ entry into BC3H-1 cells, mimics the insulin stimulation of ouabain-inhibitable 86Rb+ uptake. In contrast, incubation with amiloride or low [Na+] (10 mM), both of which inhibit Na+/H+ exchange transport, abolished the insulin stimulation of (Na+,K+)-ATPase transport activity. Furthermore, each of these insulin-stimulated transport activities displayed a similar sensitivity to amiloride. These results indicate that insulin stimulates a large increase in Na+/H+ exchange transport and that the resulting Na+ influx increases the intracellular Na+ concentration, thus activating the internal Na+ transport sites of the (Na+,K+)-ATPase. This Na+ influx is, therefore, the mediator of the insulin-induced stimulation of membrane (Na+,K+)-ATPase transport activity classically observed in muscle. 相似文献
3.
Genetic variation at the Major Histocompatibility Complex locus DQ beta was
analyzed in 233 beluga whales (Delphinapterus leucas) from seven
populations: St. Lawrence Estuary, eastern Beaufort Sea, eastern Chukchi
Sea, western Hudson Bay, eastern Hudson Bay, southeastern Baffin Island,
and High Arctic and in 12 narwhals (Monodon monoceros) sympatric with the
High Arctic beluga population. Variation was assessed by amplification of
the exon coding for the peptide binding region via the polymerase chain
reaction, followed by either cloning and DNA sequencing or single-stranded
conformation polymorphism analysis. Five alleles were found across the
beluga populations and one in the narwhal. Pairwise comparisons of these
alleles showed a 5:1 ratio of nonsynonymous to synonymous substitutions per
site leading to eight amino acid differences, five of which were
nonconservative substitutions, centered around positions previously shown
to be important for peptide binding. Although the amount of allelic
variation is low when compared with terrestrial mammals, the nature of the
substitutions in the peptide binding sites indicates an important role for
the DQ beta locus in the cellular immune response of beluga whales.
Comparisons of allele frequencies among populations show the High Arctic
population to be different (P < or = .005) from the other beluga
populations surveyed. In these other populations an allele, Dele-DQ
beta*0101-2, was found in 98% of the animals, while in the High Arctic it
was found in only 52% of the animals. Two other alleles were found at high
frequencies in the High Arctic population, one being very similar to the
single allele found in narwhal.
相似文献
4.
Variation in testosterone (T) is thought to affect the allocation of effort between reproductive and parenting strategies. Here, using a large sample of elderly American men (n = 754) and women (n = 669) we examined the relationship between T and self-reported parenthood, as well as the relationship between T and number of reported children. Results supported previous findings from the literature, showing that fathers had lower T levels than men who report no children. Furthermore, we found that among fathers T levels were positively associated with the number of children a man reports close to the end of his lifespan. Results were maintained when controlling for a number of relevant factors such as time of T sampling, participant age, educational attainment, BMI, marital status and reported number of sex partners. In contrast, T was not associated with either motherhood or the number of children women had, suggesting that, at least in this sample, T does not influence the allocation of effort between reproductive and parenting strategies among women. Findings from this study contribute to the growing body of literature suggesting that, among men, pair bonding and paternal care are associated with lower T levels, while searching and acquiring sex partners is associated with higher T levels. 相似文献
5.
Improving foliar applications of entomopathogenic nematodes by selecting adjuvants and spray nozzles
B. Beck E. Brusselman M. Moens S. Pollet F. Temmerman 《Biocontrol Science and Technology》2013,23(5):507-520
This study explores the influence of a selection of adjuvants and of three different nozzle sizes on the foliar application of entomopathogenic nematodes (EPNs). Two EPN species were studied: Steinernema feltiae and Steinernema carpocapsae. A viability test of EPNs suspended in different solutions of adjuvants showed that all selected alcohol ethoxylates and an alkyl polysaccharide have an immobilising effect on the selected nematode species. In a sedimentation test, xanthan gum proved to be the only adjuvant in a broad selection, capable of delaying sedimentation of EPNs in suspension. Without xanthan gum, sedimentation of S. carpocapsae and S. feltiae was noticeable after 20 and 10 minutes, respectively. When xanthan gum (0.3 g/L) was added to the suspension, no signs of sedimentation were noticed after 20 minutes with both EPN species. An ISO 02 flat fan nozzle can clog when spraying S. carpocapsae. A deposition test determined that an ISO 04 standard flat fan nozzle provides a higher relative deposition on cauliflower leaves and is therefore a better nozzle choice than the bigger ISO 08 standard flat fan nozzle for spraying S. carpocapsae. The addition of a spreading agent improved the deposition of S. carpocapsae. Adding xanthan gum to the EPN-spreading agent mixtures did not further improve deposition. 相似文献
6.
Lapierre C Pilate G Pollet B Mila I Leplé JC Jouanin L Kim H Ralph J 《Phytochemistry》2004,65(3):313-321
A series of transgenic poplars down-regulated for cinnamyl alcohol dehydrogenase (CAD) was analyzed by thioacidolysis. Among the lignin-derived monomers, the indene compounds that were recently shown to originate from sinapaldehyde incorporated into lignins through 8-O-4-cross-coupling, were found to increase as a function of CAD deficiency level. While these syringyl markers were recovered in substantial amounts in the most severely depressed lines, the markers for coniferaldehyde incorporation were recovered in only low amounts. In conjunction with these additional sinapaldehyde units and relative to the control samples, lignins in CAD-deficient poplar lines had less conventional syringyl-units and beta-O-4-bonds and more free phenolic groups. We found that almost half of the polymers in the most deficient lines could be solubilized in alkali and at room temperature. This unusual behavior suggests that lignins in CAD-deficient poplars occur as small, alkali-leachable lignin domains. That mainly sinapaldehyde incorporates into the lignins of CAD-deficient poplars suggests that the recently identified sinapyl alcohol dehydrogenase (SAD), which is structurally distinct from the CAD enzyme targeted herein, does not play any substantial role in constitutive lignification in poplar. 相似文献
7.
Axeldb is a database storing and integrating gene expression patterns and DNA sequences identified in a large-scale in situ hybridization study in Xenopus laevis embryos. The data are organised in a format appropriate for comprehensive analysis, and enable comparison of images of expression pattern for any given set of genes. Information on literature, cDNA clones and their availability, nucleotide sequences, expression pattern and accompanying pictures are available. Current developments are aimed toward the interconnection with other databases and the integration of data from the literature. Axeldb is implemented using an ACEDB database system, and available through the web at http://www.dkfz-heidelberg.de/abt0135/axeldb.htm 相似文献
8.
Elongation factor-1 alpha occurs as two copies in bees: implications for phylogenetic analysis of EF-1 alpha sequences in insects 总被引:5,自引:1,他引:4
We report the complete sequence of a paralogous copy of elongation factor-1
alpha (EF-1 alpha) in the honeybee, Apis mellifera (Hymenoptera: Apidae).
This copy differs from a previously described copy in the positions of five
introns and in 25% of the nucleotide sites in the coding regions. The
existence of two paralogous copies of EF-1 alpha in Drosophila and Apis
suggests that two copies of EF-1 alpha may be widespread in the
holometabolous insect orders. To distinguish between a single, ancient gene
duplication and parallel, independent fly and bee gene duplications, we
performed a phylogenetic analysis of hexapod EF-1 alpha sequences.
Unweighted parsimony analysis of nucleotide sequences suggests an ancient
gene duplication event, whereas weighted parsimony analysis of nucleotides
and unweighted parsimony analysis of amino acids suggests the contrary:
that EF-1 alpha underwent parallel gene duplications in the Diptera and the
Hymenoptera. The hypothesis of parallel gene duplication is supported both
by congruence among nucleotide and amino acid data sets and by
topology-dependent permutation tail probability (T-PTP) tests. The
resulting tree topologies are also congruent with current views on the
relationships among the holometabolous orders included in this study
(Diptera, Hymenoptera, and Lepidoptera). More sequences, from diverse
orders of holometabolous insects, will be needed to more accurately assess
the historical patterns of gene duplication in EF-1 alpha.
相似文献
9.
10.
Do CT Pollet B Thévenin J Sibout R Denoue D Barrière Y Lapierre C Jouanin L 《Planta》2007,226(5):1117-1129
Two methylation steps are necessary for the biosynthesis of monolignols, the lignin precursors. Caffeic acid O-methyltransferase (COMT) O-methylates at the C5 position of the phenolic ring. COMT is responsible for the biosynthesis of sinapyl alcohol, the precursor
of syringyl lignin units. The O-methylation at the C3 position of the phenolic ring involves the Caffeoyl CoA 3-O-methyltransferase (CCoAOMT). The CCoAOMT 1 gene (At4g34050) is believed to encode the enzyme responsible for the first O-methylation in Arabidopsis thaliana. A CCoAOMT1 promoter-GUS fusion and immunolocalization experiments revealed that this gene is strongly and exclusively expressed in
the vascular tissues of stems and roots. An Arabidopsis T-DNA null mutant named ccomt 1 was identified and characterised. The mutant stems are slightly smaller than wild-type stems in short-day growth conditions
and has collapsed xylem elements. The lignin content of the stem is low and the S/G ratio is high mainly due to fewer G units.
These results suggest that this O-methyltransferase is involved in G-unit biosynthesis but does not act alone to perform this step in monolignol biosynthesis.
To determine which O-methyltransferase assists CCoAOMT 1, a comt 1 ccomt1 double mutant was generated and studied. The development of comt 1 ccomt1 is arrested at the plantlet stage in our growth conditions. Lignins of these plantlets are mainly composed of p-hydroxyphenyl units. Moreover, the double mutant does not synthesize sinapoyl malate, a soluble phenolic. These results suggest
that CCoAOMT 1 and COMT 1 act together to methylate the C3 position of the phenolic ring of monolignols in Arabidopsis. In addition, they are both involved in the formation of sinapoyl malate and isorhamnetin. 相似文献