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991.
Zhang K Aruva MR Shanthly N Cardi CA Patel CA Rattan S Cesarone G Wickstrom E Thakur ML 《Regulatory peptides》2007,144(1-3):91-100
Vasoactive intestinal peptide and pituitary adenylate cyclase activating peptide have high affinity for VPAC1, VPAC2 and PAC1 receptors overexpressed on human cancer cells. Four potent analogues of these peptides, TP3939, TP3982, TP4200 and TP3805 were labeled with (64)Cu and evaluated ex vivo and in vivo to asses their biological activity and receptor specificity. The ultimate goal is to utilize (64)Cu analogues for positron emission tomography (PET) imaging of breast cancers in humans. Radiochemical purity of each analogue was >92%. The muscle relaxivity assay revealed IC(50) to be 5.3x10(-8) M, 4.4x10(-8) M, 8.1x10(-8) M, 8.1x10(-9) M and Kd values determined by receptor specific cell binding assays were 3.3 nM, 0.33 nM, 0.2 nM and 0.72 nM for TP3805, TP3939, TP3982, and TP4200 respectively. The receptor affinity, using human breast cancer tissues, was 10.93 times greater than normal breast tissues. RT-PCR confirmed increased VPAC1 receptor expression on human breast tumor cells over normal cells and corroborated with autoradiography data. The blood clearance was rapid and in vivo translocation of (64)Cu to plasma protein was <15%. Data demonstrate that these analogues are potent, have uncompromised biological activity and are worthy of further evaluation for accurate PET imaging of human breast cancers and in determining malignant and benign lesions. 相似文献
992.
Alterations in the genome and the epigenome are common in most cancers. Changes in epigenetic signatures, including aberrant DNA methylation and histone deacetylation, are among the most prevalent modifications in cancer and lead to dramatic changes in gene expression patterns. Because DNA methylation and histone deacetylation are reversible processes, they have become attractive as targets for cancer epigenetic therapy, both as single agents and as 'enhancing' agents for other treatment strategies. In this review we discuss our current view of the mammalian epigenome, this view has changed over the years because of the availability of novel technologies. We further demonstrate how the profound understanding of epigenetic alterations in cancer will help develop novel strategies for epigenetic therapies. 相似文献
993.
The role of secondary vegetation in restoring soil fertility during shifting cultivation in the tropics is well known. Yet
the effect of secondary succession on the spatial patterns of soil properties has received little attention. To determine
whether changes in the plant community as a result of shifting cultivation affect the scale of spatial dependence for biologically
important soil nutrients, we sampled three dry tropical forest stands in Campeche, Mexico. These stands represented a gradient
of cultivation history: one mature forest stand, a forest fallow that had undergone one cultivation-fallow cycle, and a forest
fallow that had undergone two cultivation-fallow cycles. We used an analysis of semivariance to quantify the scale and magnitude
of spatial dependence for organic matter content (OM), phosphorus (P), potassium (K), and aluminum (Al) in each stand. The
scale of spatial dependence varied with cultivation history, but the degree of spatial dependence did not differ among stands.
In the mature forest P and K were autocorrelated over distances >7.5 m. In the forest fallows 48–88% of the variation in soil
P and K was autocorrelated over distances up to 1.1–5.1 m. In contrast, the range of autocorrelation for Al (∼2.5 m) did not
differ among stands. We conclude that shifting cultivation changes the range of autocorrelation for biologically important
soil nutrients at a scale that may influence plant growth. The finer scaled pattern of soil nutrients in forest fallows is
likely to persist with continued shifting cultivation, since fallows are cleared every 3–15 years. 相似文献
994.
Regional ecosystem structure and function: ecological insights from remote sensing of tropical forests 总被引:7,自引:1,他引:6
Chambers JQ Asner GP Morton DC Anderson LO Saatchi SS Espírito-Santo FD Palace M Souza C 《Trends in ecology & evolution》2007,22(8):414-423
Ecological studies in tropical forests have long been plagued by difficulties associated with sampling the crowns of large canopy trees and large inaccessible regions, such as the Amazon basin. Recent advances in remote sensing have overcome some of these obstacles, enabling progress towards tackling difficult ecological problems. Breakthroughs have helped transform the dialog between ecology and remote sensing, generating new regional perspectives on key environmental gradients and species assemblages with ecologically relevant measures such as canopy nutrient and moisture content, crown area, leaf-level drought responses, woody tissue and surface litter abundance, phenological patterns, and land-cover transitions. Issues that we address here include forest response to altered precipitation regimes, regional disturbance and land-use patterns, invasive species and landscape carbon balance. 相似文献
995.
Water deficits accelerate ripening and induce changes in gene expression regulating flavonoid biosynthesis in grape berries 总被引:9,自引:0,他引:9
Water deficits consistently promote higher concentrations of anthocyanins in red winegrapes and their wines. However, controversy
remains as to whether there is any direct effect on berry metabolism other than inhibition of growth. Early (ED) and late
(LD) season water deficits, applied before or after the onset of ripening (veraison), were imposed on field grown Vitis vinifera “Cabernet Sauvignon”, and the responses of gene expression in the flavonoid pathway and their corresponding metabolites were
determined. ED accelerated sugar accumulation and the onset of anthocyanin synthesis. Both ED and LD increased anthocyanin
accumulation after veraison. Expression profiling revealed that the increased anthocyanin accumulation resulted from earlier
and greater expression of the genes controlling flux through the anthocyanin biosynthetic pathway, including F3H, DFR, UFGT and GST. Increases in total anthocyanins resulted predominantly from an increase of 3′4′5′-hydroxylated forms through the differential
regulation of F3′H and F3′5′H. There were limited effects on proanthocyanidin, other flavonols, and on expression of genes committed to their synthesis.
These results demonstrate that manipulation of abiotic stress through applied water deficits not only modulates compositional
changes during berry ripening, but also alters the timing of particular aspects of the ripening process. 相似文献
996.
Lip reconstruction remains challenging. Accurate analysis of the defect and a thorough understanding of the anatomy and options for reconstruction will maintain the functional and aesthetic quality of this sensitive area. 相似文献
997.
998.
999.
Stone KL Bjornson RD Blasko GG Bruce C Cofrancesco R Carriero NJ Colangelo CM Crawford JK Crawford JM daSilva NC Deluca JD Elliott JI Elliott MM Flory PJ Folta-Stogniew EJ Gulcicek E Kong Y Lam TT Lee JY Lin A LoPresti MB Mane SM McMurray WJ Tikhonova IR Westman S Williams NA Wu TL Hongyu Z Williams KR 《The Yale journal of biology and medicine》2007,80(4):195-211
1000.
Zysling DA Demas GE 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2007,177(3):339-347
Individuals of many species experience marked seasonal variation in environmental conditions and must adapt to potentially
large fluctuations in energy availability and expenditure. Seasonal changes in immunity have likely evolved as an adaptive
mechanism to cope with seasonal stressors. In addition, these changes may be constrained by seasonal fluctuations in energy
availability. The goal of this study was to assess the role of energetic trade-offs associated with seasonal variation in
immunity. In addition to body fat stores, metabolic fuels (e.g., glucose) may affect immune function in seasonally breeding
rodents. In this study we experimentally reduced energy availability via injections of the metabolic inhibitor 2-deoxy-d-glucose (2-DG) in long- and short-day housed Siberian hamsters (Phodopus sungorus) and then examined antigen-specific antibody production. Metabolic stress decreased antibody response compared with control
animals in long days. In contrast, no difference was observed between treatment groups in short days. These data suggest that
reductions in energy availability suppress immunity and short days buffer organisms against glucoprivation-induced immunosuppression. 相似文献