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971.
ObjectiveTo determine whether vitamin E supplementation influences the incidence or rate of progression of age related maculopathy (AMD).DesignProspective randomised placebo controlled clinical trial.SettingAn urban study centre in a residential area supervised by university research staff.Participants1193 healthy volunteers aged between 55 and 80 years; 73% completed the trial on full protocol.InterventionsVitamin E 500 IU or placebo daily for four years.ResultsThe incidence of early age related macular degeneration (early AMD 3) was 8.6% in those receiving vitamin E versus 8.1% in those on placebo (relative risk 1.05, 95% confidence interval 0.69 to 1.61). For late disease the incidence was 0.8% versus 0.6% (1.36, 0.67 to 2.77). Further analysis showed no consistent differences in secondary outcomes.ConclusionDaily supplement with vitamin E supplement does not prevent the development or progression of early or later stages of age related macular degeneration.

What is already known on this topic

Age related macular degeneration is the leading cause of loss of vision and blindness in elderly people; for people aged ⩾90 years, two out of every three will be affected and one in four will become blindCurrently, there are no methods of prevention or treatment in most cases, though a third of cases are due to cigarette smokingAntioxidant vitamins have been suggested as a possible prevention

What this study adds

Daily supplementation with 500 mg vitamin E for four years did not alter the incidence or progression of AMD  相似文献   
972.
With accelerating rates of obesity and type 2 diabetes world-wide, interest in studying the adipocyte and adipose tissue is increasing. Human adipose derived stem cells - differentiated to adipocytes in vitro - are frequently used as a model system for white adipocytes, as most of their pathways and functions resemble mature adipocytes in vivo. However, these cells are not completely like in vivo mature adipocytes. Hosting the cells in a more physiologically relevant environment compared to conventional two-dimensional cell culturing on plastic surfaces, can produce spatial cues that drive the cells towards a more mature state. We investigated the adipogenesis of adipose derived stem cells on electro spun polycaprolactone matrices and compared functionality to conventional two-dimensional cultures as well as to human primary mature adipocytes. To assess the degree of adipogenesis we measured cellular glucose-uptake and lipolysis and used a range of different methods to evaluate lipid accumulation. We compared the averaged results from a whole population with the single cell characteristics – studied by coherent anti-Stokes Raman scattering microscopy - to gain a comprehensive picture of the cell phenotypes. In adipose derived stem cells differentiated on a polycaprolactone-fiber matrix; an increased sensitivity in insulin-stimulated glucose uptake was detected when cells were grown on either aligned or random matrices. Furthermore, comparing differentiation of adipose derived stem cells on aligned polycaprolactone-fiber matrixes, to those differentiated in two-dimensional cultures showed, an increase in the cellular lipid accumulation, and hormone sensitive lipase content. In conclusion, we propose an adipocyte cell model created by differentiation of adipose derived stem cells on aligned polycaprolactone-fiber matrices which demonstrates increased maturity, compared to 2D cultured cells.  相似文献   
973.
Soil organic matter (SOM) turnover is crucial for soil quality and fertility in biogeochemical carbon cycle dynamics that can influence the fluxes of greenhouse gases. This research was focused to acquire deeper understanding of the mechanisms leading to decomposition of plant tissue and SOM persistence against both aerobic and anaerobic biodegradation. Decomposition rates of a various biomass types were studied conducting experiments in both aerobic and anaerobic environments. Different analytical approaches were applied in order to characterize biomass at chemical and physical levels. Combined statistical approaches were used to examine the relationships between carbon mineralization and chemical/physical characteristics. The obtained results revealed that degradation was significantly and negatively correlated with the micro-porosity surface (surface of pores of 0.3–1.5 nm of diameter). The multiple regressions performed by using partial least squares modelling enabled describing biomass biodegradability under either aerobic and anaerobic condition by using micro-porosity and aromatic-C content (assumed to be representative of lignin) as independent variables (R2 = 0.97, R cv 2  = 0.95 for aerobic condition; R2 = 0.99, R cv 2  = 0.98 for anaerobic condition, respectively). These results corroborate the hypothesis that plant tissues are physically protected from enzymatic attack by a microporous “sheath” that limits enzyme penetration into cell wall, and demonstrate the key role played by aromatic carbon, because of its chemical protection of the other cell wall polymers and its contribution to the three-dimensional (3D) cell wall structure.  相似文献   
974.
Salicylic acid (SA), which is known as a signal molecule in the induction of defense mechanisms in plants, could be a promising compound for the reduction of stress sensitivity. The aim of the present work was to investigate the distribution of SA in young pea (Pisum sativum L.) seedlings grown from seeds soaked in 3H-labeled SA solution before sowing, and to study the physiological changes induced by this seed treatment. The most pronounced changes in SA levels occurred in the epicotyl and the seeds. Radioactivity was detected only in the bound form of SA, the majority of which was localized in the seeds, and only a very low level of radioactivity was detected in the epicotyl. SA pre-treatment increased the expression of the chorismate synthase and isochorismate synthase genes in the epicotyl. Pre-soaking the seeds in SA increased the activities of some antioxidant enzymes, namely ascorbate peroxidase (EC 1.11.1.11) and guaiacol peroxidase (EC 1.11.1.7) and the level of ortho-hydroxycinnamic acid, but decreased the level of polyamines. These results suggest that the increased level of free and bound SA detected in plants growing from seeds soaked in SA solution before sowing is the product of de novo synthesis, rather than having been taken up and mobilized by the plants.  相似文献   
975.
Transforming growth factor beta 1 (TGF-beta 1) and insulin-like growth factor I (IGF-I) have contrasting effects on cell cycle regulation in thyroid cells and TGF-beta 1 induces a dramatic decrease in IGF-I-induced cell proliferation. The aim of the present study was to investigate the molecular mechanism of cross-talk between TGF-beta 1 and IGF-I in FRTL-5 cells. TGF-beta 1 affected IGF-I-stimulated insulin receptor substrate 1 (IRS-1) tyrosine phosphorylation and its association with Grb2 protein. Moreover, TGF-beta 1 decreased the IGF-I-induced tyrosine phosphorylation of the adaptor protein CrkII and its association with the IGF-I receptor. These results were accompanied by TGF-beta 1 inhibition of IGF-I-stimulated mitogen-activated protein kinase phosphorylation and activation. Conversely, TGF-beta 1 did not alter IGF-I-stimulated IRS-1-associated phosphatidylinositol 3-kinase activity, IGF-I-induced tyrosine phosphorylation of Shc, and its binding to Grb2. Taken together, these findings provide a molecular basis for the growth-inhibitory action of TGF-beta 1 on the IGF-I-induced mitogenic effect.  相似文献   
976.
Nitric oxide (NO) is a signaling molecule implicated in a spectrum of cellular processes including neuronal differentiation. The signaling pathway triggered by NO in physiological processes involves the activation of soluble guanylate cyclase and S-nitrosylation of proteins, and, as recently proposed, nitration of tyrosine residues in proteins. However, little is known about the mechanisms involved and the target proteins for endogenous NO during the progression of neuronal differentiation. To address this question, we investigated the presence, localization, and subcellular distribution of nitrated proteins during neurotrophin-induced differentiation of PC12 cells. We find that some proteins show basal levels of tyrosine nitration in PC12 cells grown in the absence of nerve growth factor (NGF) and that nitration levels increase significantly after 2 days of incubation with this neurotrophin. Nitrated proteins accumulate over a period of several days in the presence of NGF. We demonstrate that this nitration is coupled to activation of nitric oxide synthase. The subcellular distribution of nitrated proteins changes during PC12 cell differentiation, displaying a shift from the cytosolic to the cytoskeletal fraction and we identified alpha-tubulin as the major target of nitration in PC12 cells by N-terminal sequence and MALDI-TOF analyses. We conclude that tyrosine nitration of proteins could be a novel molecular mechanism involved in the signaling pathway by which NO modulates NGF-induced differentiation in PC12 cells.  相似文献   
977.
In HeLa cells the expression of the BAG-3 gene, a member of the BAG family, is regulated by heavy metals and temperature, with kinetics of accumulation of mRNAs similar to Hsp70 and metallothioneins. Western blot assays performed with a polyclonal anti-BAG-3 antibody confirmed that higher levels of the protein were present in the cells following heat and metal exposure. By immunofluorescence techniques and cell fractionation assays we demonstrated that following stress BAG-3 protein concentrated in the rough endoplasmic reticulum and associated with the heavy membrane fraction. The role of BAG-3 protein during apoptosis and cellular stress is discussed.  相似文献   
978.
Seven Y-chromosome microsatellite loci (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, and DYS393) were analyzed in three populations from sub-Saharan Africa: the Bamileke and Ewondo populations from Cameroon and the Hutu from Rwanda. Complete typing was obtained for 112 individuals, and a total of 53 different haplotypes was observed. The single-locus gene diversity, averaged across populations, ranges from 0.100 for the DYS392 locus to 0.610 for the DYS389I locus. The haplotype diversity ranges from 0.832 (Ewondo) to 0.965 (Hutu), with an intermediate value of 0.918 in the Bamileke. The diversity among Bamileke, Ewondo, Hutu, and other sub-Saharan populations selected from the literature was analyzed using both a classical (F(ST)) and a stepwise-based (R(ST)) genetic distance method. The pattern of interpopulational diversity based on F(ST) was congruent with anthropological knowledge, while that based on R(ST) revealed unexpected and unconvincing population affinities. From a practical point of view, our study indicates that Y-chromosome microsatellite data may provide useful information for analyses of interpopulational diversity among sub-Saharan populations if an adequate number of loci and individuals along with an appropriate genetic distance method are used. On a theoretical ground, we propose that the lesser performance of R(ST) compared to F(ST) could be explained by the important role played by genetic drift in shaping the relationships among examined populations.  相似文献   
979.
No evidence of fetal DNA persistence in maternal plasma after pregnancy   总被引:8,自引:0,他引:8  
Short- and long-term persistence of fetal DNA in maternal plasma has been investigated. Short-term persistence at very low concentration was detected in 47 out of 105 women within two days after delivery. Twelve out of 13 samples re-tested within three days scored negative. No long-term persistence was detected in 172 women who had previous sons or abortions. Molecular microchimerism due to circulating fetal DNA persisting from previous pregnancies should not hamper non-invasive plasma-based prenatal testing.  相似文献   
980.
The shoot apical meristem (SAM), initially formed during embryogenesis, gives rise to the aboveground portion of the maize (Zea mays) plant. The shootless phenotype (sml) described here is caused by disruption of SAM formation due to the synergistic interaction of mutations at two genetic loci. Seedlings must be homozygous for both sml (shootmeristemless), and the unlinked dgr (distorted growth) loci for a SAM-less phenotype to occur. Seedlings mutant only for sml are impaired in their morphogenesis to different extents, whereas the dgr mutation alone does not have a recognisable phenotype. Thus, dgr can be envisaged as being a dominant modifier of sml and the 12 (normal):3 (distorted growth):1 (shoot meristemless) segregation observed in the F(2) of the double heterozygote is the result of the interaction between the sml and dgr genes. Other segregation patterns were also observed in the F(2), suggesting instability of the dgr gene. Efforts to rescue mutant embryos by growth on media enriched with hormones have been unsuccessful so far. However, mutant roots grow normally on medium supplemented with kinetin at a concentration that suppresses wild-type root elongation, suggesting possible involvement of the mutant in the reception or transduction of the kinetin signal or transport of the hormone. The shootless mutant appears to be a valuable tool with which to investigate the organization of the shoot meristem in monocots as well as a means to assay the origins and relationships between organs such as the scutellum, the coleoptile, and leaves that are initiated during the embryogenic process.  相似文献   
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