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排序方式: 共有513条查询结果,搜索用时 15 毫秒
51.
Cyracure UVR 6105 is a cycloaliphatic epoxy monomer and has both carboxylate and epoxy groups, with the potential for rapid polymerization. It is widely used in industry for the preparation of inks, resins, coatings, and was proposed for incorporation into dental composites. The objective of this study was to determine the mutagenic potential of this chemical related to its metabolite products. Several doses of Cyracure UVR 6105 were dissolved in DMSO and subjected to the Ames Salmonella mutagenicity assay. A metabolic activation system (S9-mix) was used consisting of Arochlor-induced liver S9 homogenate enriched with NADP and glucose-6-phosphate cofactors. In contrast to studies without S9-mix, Cyracure UVR 6105 exhibited enhanced genotoxic activities with strains TA100 and TA1535 in the presence of liver S9-mix. From in vitro metabolism of Cyracure UVR 6105 with S9-mix, as used in the Ames assay, several metabolites were identified. The alcohol metabolite, 3,4-epoxycyclohexylmethanol, containing intact epoxy group was identified in the organic solvent extract. This metabolite was synthesized and proved to be mutagenic against TA100 when assayed in the presence and absence of S9-mix. Results showed that the increased mutagenicity of Cyracure UVR-6105 in the presence of liver enzymes is due to the formation of the mutagenic metabolite 3,4-epoxycyclohexylmethanol. 相似文献
52.
Pruneda A Pinart E Bonet S Yeung CH Cooper TG 《Molecular reproduction and development》2006,73(7):859-865
Concentrations of D-glucose, D-fructose and D-sorbitol were quantified in porcine epididymal fluid by spectrofluorimetric assays and aldose reductase (AR) and sorbitol dehydrogenase (SDH) were located immunohistochemically in the epididymal epithelium. Glucose and fructose concentrations were low (<1 mM) and decreased in the cauda whereas sorbitol concentration (4-7 mM) was rather uniform along the duct. AR was luminally located on microvilli in the caput and corpus with less presence distally and was present in the lumen. SDH was present apically and basally in epithelial cells throughout the epididymis and in the lumen. The observations are consistent with diffusion of circulating glucose into the lumen, its conversion via AR to sorbitol which accumulates in the lumen and the action of SDH on sorbitol to produce fructose. Sperm metabolism of glucose and fructose may explain their lower concentrations in the cauda and sorbitol could be a metabolic substrate or osmolyte required for volume regulation. 相似文献
53.
Effect of ice melting on bacterial carbon fluxes channelled by viruses and protists in the Arctic Ocean 总被引:1,自引:0,他引:1
Julia A. Boras M. Montserrat Sala Jesus M. Arrieta Elisabet L. Sà Jorge Felipe Susana Agustí Carlos M. Duarte Dolors Vaqué 《Polar Biology》2010,33(12):1695-1707
During the last few years, extensive sea ice melting in the Arctic due to climate change has been detected, which could potentially
modify the organic carbon fluxes in these waters. In this study, the effect of sea ice melting on bacterial carbon channelling
by phages and protists has been evaluated in the northern Greenland Sea and Arctic Ocean. Grazing on bacteria by protists
was evaluated using the FLB disappearance method. Lysis of bacteria due to viral infections was measured using the virus reduction
approach. Losses of bacterial production caused by protists (PMMBP) dominated losses caused by viruses (VMMBP) throughout the study. Lysogenic viral production was detected in 7 out of 21 measurements and constituted from 33.9 to 100.0%
of the total viral production. Significantly higher PMMBP and lower VMMBP were detected in waters affected by ice melting compared with unaffected waters. Consequently, significantly more bacterial
carbon was channelled to the higher trophic levels in affected waters (13.05 ± 5.98 μgC l−1 day−1) than in unaffected waters (8.91 ± 8.33 μgC l−1 day−1). Viruses channelled 2.63 ± 2.45 μgC l−1 day−1 in affected waters and 4.27 ± 5.54 μgC l−1 day−1 in unaffected waters. We conclude that sea ice melting in the Arctic could modify the carbon flow through the microbial food
web. This process may be especially important in the case of massive sea ice melting due to climate change. 相似文献
54.
John A. Carver Peter J. Duggan Heath Ecroyd Yanqin Liu Adam G. Meyer C. Elisabet Tranberg 《Bioorganic & medicinal chemistry》2010,18(1):222-228
Reduced and carboxymethylated-κ-casein (RCM-κ-CN) is a milk-derived amyloidogenic protein that readily undergoes nucleation-dependent aggregation and amyloid fibril formation via a similar pathway to disease-specific amyloidogenic peptides like amyloid beta (Aβ), which is associated with Alzheimer’s disease. In this study, a series of flavonoids, many known to be inhibitors of Aβ fibril formation, were screened for their ability to inhibit RCM-κ-CN fibrilisation, and the results were compared with literature data on Aβ inhibition. Flavonoids that had a high degree of hydroxylation and molecular planarity gave good inhibition of RCM-κ-CN fibril formation. IC50 values were between 10- and 200-fold higher with RCM-κ-CN than literature results for Aβ fibril inhibition, however, with few exceptions, they showed a similar trend in potency. The convenience and reproducibility of the RCM-κ-CN assay make it an economic alternative first screen for Aβ inhibitory activity, especially for use with large compound libraries. 相似文献
55.
Hanschmann EM Lönn ME Schütte LD Funke M Godoy JR Eitner S Hudemann C Lillig CH 《The Journal of biological chemistry》2010,285(52):40699-40705
The proteins from the thioredoxin family are crucial actors in redox signaling and the cellular response to oxidative stress. The major intracellular source for oxygen radicals are the components of the respiratory chain in mitochondria. Here, we show that the mitochondrial 2-Cys peroxiredoxin (Prx3) is not only substrate for thioredoxin 2 (Trx2), but can also be reduced by glutaredoxin 2 (Grx2) via the dithiol reaction mechanism. Grx2 reduces Prx3 exhibiting catalytic constants (K(m), 23.8 μmol·liter(-1); V(max), 1.2 μmol·(mg·min)(-1)) similar to Trx2 (K(m), 11.2 μmol·liter(-1); V(max), 1.1 μmol·(mg·min)(-1)). The reduction of the catalytic disulfide of the atypical 2-Cys Prx5 is limited to the Trx system. Silencing the expression of either Trx2 or Grx2 in HeLa cells using specific siRNAs did not change the monomer:dimer ratio of Prx3 detected by a specific 2-Cys Prx redox blot. Only combined silencing of the expression of both proteins led to an accumulation of oxidized protein. We further demonstrate that the distribution of Prx3 in different mouse tissues is either linked to the distribution of Trx2 or Grx2. These results introduce Grx2 as a novel electron donor for Prx3, providing further insights into pivotal cellular redox signaling mechanisms. 相似文献
56.
SNPStats: a web tool for the analysis of association studies 总被引:4,自引:0,他引:4
57.
Abramsson-Zetterberg L Durling LJ Yang-Wallentin F Rytter E Vessby B 《Mutation research》2006,603(1):33-40
Folic acid has a well-documented stabilising effect on chromosomes. A correlation between folate status and chromosome stability in humans has been reported in studies that were restricted to certain subpopulations, e.g., folate-deficient persons. The goal of the present investigation was to clarify if there also is a correlation between folate status and chromosome stability among individuals without any folate deficiency. The method used here is the recently developed flow cytometry-based micronucleus assay in human transferrin-positive reticulocytes (MN-Trf-Ret). In a blood sample, separation of the very young reticulocytes from the mature erythrocytes makes this micronucleus assay possible. This investigation comprises three studies (cross-sectional, giving baseline data), two of which are connected to an intervention study. In the three cross-sectional studies (total number of subjects, 99) the frequency of MN-Trf-Ret (fMN-Trf-Ret) was measured and compared with the serum folate status. In two of the studies also serum homocysteine and Vitamin B12 were measured and compared with the baseline fMN-Trf-Ret. Combining the results from the three cross-sectional studies, a negative correlation between folate status and fMN-Trf-Ret was obtained (p<0.05). The goal of the intervention studies was to clarify if different nutritional supplementations had any effect on the fMN-Trf-Ret and the cell proliferation (percentage polychromatic erythrocytes, PCE). Each of the two studies involved two groups, one placebo and one supplemented group. In one of the studies the supplementation was folic acid, 1000 microg/day during 1 week (n=30, both sexes); in the other intervention study, folic acid (800 microg/day), B12 (20 microg/day) and B6 (4 mg/day) were taken during 1 week (n=29, both sexes). No significant difference in %PCE or fMN-Trf-Ret between the two groups was found in either of the two intervention studies. 相似文献
58.
59.
Peña C Wahlberg N Weingartner E Kodandaramaiah U Nylin S Freitas AV Brower AV 《Molecular phylogenetics and evolution》2006,40(1):29-49
We have inferred the first empirically supported hypothesis of relationships for the cosmopolitan butterfly subfamily Satyrinae. We used 3090 base pairs of DNA from the mitochondrial gene COI and the nuclear genes EF-1alpha and wingless for 165 Satyrinae taxa representing 4 tribes and 15 subtribes, and 26 outgroups, in order to test the monophyly of the subfamily and elucidate phylogenetic relationships of its major lineages. In a combined analysis, the three gene regions supported an almost fully resolved topology, which recovered Satyrinae as polyphyletic, and revealed that the current classification of suprageneric taxa within the subfamily is comprised almost completely of unnatural assemblages. The most noteworthy findings are that Manataria is closely related to Melanitini; Palaeonympha belongs to Euptychiina; Oressinoma, Orsotriaena and Coenonympha group with the Hypocystina; Miller's (1968). Parargina is polyphyletic and its components group with multiple distantly related lineages; and the subtribes Elymniina and Zetherina fall outside the Satyrinae. The three gene regions used in a combined analysis prove to be very effective in resolving relationships of Satyrinae at the subtribal and tribal levels. Further sampling of the taxa closely related to Satyrinae, as well as more extensive sampling of genera within the tribes and subtribes for this group will be critical to test the monophyly of the subfamily and establish a stronger basis for future biogeographical and evolutionary studies. 相似文献
60.
Lídia Perea Lorena Rodríguez-Rubio Juan C Nieto Carlos Zamora Elisabet Cant German Soriano Maria Poca Pedro Blanco-Picazo Ferran Navarro Maite Muniesa Silvia Vidal 《Experimental biology and medicine (Maywood, N.J.)》2021,246(11):1263
Bacteriophages are present in fluids from cirrhosis patients. However, their effect on the immune response is unknown. In this work, we explore the role of phages in the phenotype, function, and cytokine production of monocytes. We stimulated healthy monocytes with five different butanol-purified phage suspensions infective for Gram-negative and Gram-positive bacteria. We studied the expression of the monocyte markers involved in lipopolysaccharide recognition (LPS; CD14), antigen presentation (HLA-DR) and co-stimulation (CD86), and the concentration of induced cytokines (TNF-α, IFN-α, and IL-10) by phages. To confirm the direct role of phages without the interference of contaminating soluble LPS in phage suspensions, polymyxin B was added to the cell cultures. Phagocytosis experiments were assessed by flow cytometry using labeled phage suspensions. We observed that butanol-purified phages reduced the surface levels of CD14 and CD86 in monocytes and increased the secreted levels of TNF-α and IL-10 compared with the control sample containing only butanol buffer. All phage suspensions showed downregulation of HLA-DR expression but only Staphylococcus aureus phage contaminated with Escherichia coli reached statistical significance. The addition of polymyxin B did not restore the monocytic response induced by phages, suggesting that the effect was not caused by the presence of LPS. Monocytes were able to phagocyte phages in a dose- and time-dependent manner. To conclude, the phagocytosis of butanol-purified phages altered the phenotype and cytokine production of monocytes suggesting they become tolerogenic. 相似文献