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971.
972.
We have determined the abilities of (E)-ferulic acid, (E)-p-coumaric acid and (E,E)-5-5-dehydrodiferulic acid to protect against different types of mutation in a simple bacterial model. These antimutagenic properties were compared with those of the related compound curcumin, and also with those of an extract containing hydroxycinnamic acids obtained by the saponification of the cell walls of wheat coleoptiles. Three known mutagens, bleomycin, hydrogen peroxide and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) were used to chemically induce reversion mutation, while the known antimutagen Trolox was used as a positive control. Both the pure hydroxycinnamic acids and the extract from the cell walls showed antimutagenic properties. It is known that hydroxycinnamic acids ester-linked to plant cell walls can be released in the human colon by the action of microbial esterases. Providing the current data extrapolate to mammalian cells, they suggest that antimutagenic properties of hydroxycinnamic acids released from plant cell walls could play a role in dietary fibre protection against cancer. 相似文献
973.
Su BN Kang YH Pinos RE Santarsiero BD Mesecar AD Soejarto DD Fong HH Pezzuto JM Kinghorn AD 《Phytochemistry》2003,64(1):293-302
Coussaric acid (1), a triterpenoid based on an ursane skeleton, and an oleanane-type triterpene acid, 3-epi-spathodic acid (2), as well as four known compounds, barbinervic acid, scutellaric acid, stigmasterol and stigmasterol glucoside, have been isolated from an EtOAc-soluble extract of the stems of Coussarea brevicaulis. The structures of compounds 1 and 2 were elucidated on the basis of spectroscopic investigation, and single-crystal X-ray crystallography was used to confirm the structure of 1. The absolute stereochemistry of 1 was established by chemical transformations and by the Mosher ester procedure. The potential of the isolates and chemical transformation products to induce quinone reductase was evaluated in mouse Hepa lclc7 hepatoma cells. 相似文献
974.
Mathy JA Lenton K Nacamuli RP Fong KD Song HM Fang TD Yang GP Longaker MT 《Plastic and reconstructive surgery》2003,112(2):528-539
975.
Nacamuli RP Fong KD Warren SM Fang TD Song HM Helms JA Longaker MT 《Plastic and reconstructive surgery》2003,112(5):1328-1335
976.
Fong KD Warren SM Loboa EG Henderson JH Fang TD Cowan CM Carter DR Longaker MT 《Plastic and reconstructive surgery》2003,112(5):1312-1327
The human brain grows rapidly during the first 2 years of life. This growth generates tensile strain in the overlying dura mater and neurocranium. Interestingly, it is largely during this 2-year growth period that infants are able to reossify calvarial defects. This clinical observation is important because it suggests that calvarial healing is most robust during the period of active intracranial volume expansion. With a rat model, it was previously demonstrated that immature dura mater proliferates more rapidly and produces more osteogenic cytokines and markers of osteoblast differentiation than does mature dura mater. It was therefore hypothesized that mechanical strain generated by the growing brain induces immature dura mater proliferation and increases osteogenic cytokine expression necessary for growth and healing of the overlying calvaria. Human and rat (n = 40) intracranial volume expansion was calculated as a function of age. These calculations demonstrated that 83 percent of human intracranial volume expansion is complete by 2 years of age and 90 percent of Sprague-Dawley rat intracranial volume expansion is achieved by 2 months of age. Next, the maximal daily circumferential tensile strains that could be generated in immature rat dura mater were calculated, and the corresponding daily biaxial tensile strains in the dura mater during this 2-month period were determined. With the use of a three-parameter monomolecular growth curve, it was calculated that rat dura mater experiences daily equibiaxial strains of at most 9.7 percent and 0.1 percent at birth (day 0) and 60 days of age, respectively. Because it was noted that immature dural cells may experience tensile strains as high as approximately 10 percent, neonatal rat dural cells were subjected to 10 percent equibiaxial strain in vitro, and dural cell proliferation and gene expression profiles were analyzed. When exposed to mechanical strain, immature dural cells rapidly proliferated (5.8-fold increase in proliferating cell nuclear antigen expression at 24 hours). Moreover, mechanical strain induced marked up-regulation of dural cell osteogenic cytokine production; transforming growth factor-beta1 messenger RNA levels increased 3.4-fold at 3 hours and fibroblast growth factor-2 protein levels increased 4.5-fold at 24 hours and 5.6-fold at 48 hours. Finally, mechanical strain increased dural cell expression of markers of osteoblast differentiation (2.8-fold increase in osteopontin levels at 3 hours). These findings suggest that mechanical strain can induce changes in dura mater biological processes and gene expression that may play important roles in coordinating the growth and healing of the neonatal calvaria. 相似文献
977.
Hayashi K Fong KS Mercier F Boyd CD Csiszar K Hayashi M 《Journal of molecular histology》2004,35(8-9):845-855
Lysyl oxidase (LOX) and lysyl oxidase-like (LOXL) are extracellular enzymes that deaminate peptidyl lysyl residues involved in the cross-linking of fibrillar collagens and elastin. While LOX is required for the survival of newborn mice, the role of LOXL during development remains unclear. Studies have shown that the same cell types express LOX and LOXL in the same tissues, but no functional differences have been established. We have compared the immunohistochemical localization of LOX and LOXL in various tissues from normal, young adult mice. LOX and LOXL were co-localized in the skin, aorta, heart, lung, liver and cartilage, but were localized to different areas in the kidney, stomach, small intestine, colon, retina, ovary, testis and brain. LOXL expression was further examined in tissues from different developmental stages. In embryonic mice (10.5–14.5 dpc), LOXL immunostaining was abundant in the heart, liver, intestine, and neural tube. LOXL was present in most major organs in late fetal (16.5 dpc) and newborn mice, but generally diminished as animals aged. Immunoreactivity was significantly reduced in the heart, lung, kidney and liver of 2 year-old mice, but remained prevalent in the skin and tongue. LOX and LOXL were also found in the nuclei of cells in a number of tissues. These results indicate that LOXL has a role during mouse development and in the maintenance of adult tissues. 相似文献
978.
Predicting specificity in bZIP coiled-coil protein interactions 总被引:2,自引:0,他引:2
We present a method for predicting protein-protein interactions mediated by the coiled-coil motif. When tested on interactions between nearly all human and yeast bZIP proteins, our method identifies 70% of strong interactions while maintaining that 92% of predictions are correct. Furthermore, cross-validation testing shows that including the bZIP experimental data significantly improves performance. Our method can be used to predict bZIP interactions in other genomes and is a promising approach for predicting coiled-coil interactions more generally. 相似文献
979.
Genetic and physical irregularities associated with the mating type locus of the oomycete, Phytophthora infestans, were revealed by analyzing a contig spanning the locus that was constructed using a bacterial artificial chromosome library. Contigs from both homologs of an A1 strain A/a genotype at mating type locus) had chromosome-specific differences, flanked by regions of similarity. Such heteromorphism was detected within multiple isolates. The mating type locus was narrowed to a 60-70kb interval by genetic mapping of candidate genes, identified using a cDNA library. During these analyses, an unusual isolate of P. infestans was identified in which the mating type determinant had apparently translocated from its location in typical strains. Comparative mapping of the cDNAs between P. infestans and P. parasitica revealed partial synteny between the species however; substantial rearrangements existed and no cDNA was tightly linked to mating type in P. parasitica. These findings add to previous observations of unusual genetic behavior involving mating type in Phytophthora. 相似文献
980.