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81.
Andrea Manni Rita Wechter Lisa Wei Daniel Heitjan Laurence Demers 《Journal of cellular physiology》1995,163(1):129-136
Polyamines (PA) have been shown to be critical mediators of estradiol-induced breast cancer cell proliferation. This finding suggests that constitutive activation of the PA pathway may promote tumor progression, possibly leading to hormone independence. To test this hypothesis, we transfected hormone-responsive MCF-7 breast cancer cells with a complementary DNA coding for ornithine-decarboxylase (ODC), the first rate-limiting enzyme in PA biosynthesis. Marked ODC over-expression observed in stably transfected clones was associated with a selective increase in cellular putrescine content, while spermidine and spermine levels were not altered. ODC-overexpressing MCF-7 cells were resistant to the antiproliferative effects of low but not high concentrations of the enzyme inhibitor, α-difluoromethylornithine. In agreement with our hypothesis, sensitivity to the growth-promoting action of estradiol was reduced by approximately one third (P < 0.001) in ODC-overexpressing MCF-7 cells compared with vector-only transfected clones. Basal growth under anchorage-dependent conditions was only marginally increased by ODC overexpression (P = 0.048), while clonogenicity in soft agar was actually reduced. These data suggest that activation of PA biosynthesis may contribute in part to the acquisition of estrogen independence by breast cancer cells. Since only putrescine content was increased as a result of ODC overexpression, these data may underestimate the overall influence of the PA pathway on breast cancer phenotype. © 1995 Wiley-Liss, Inc. 相似文献
82.
83.
Susanne Metzger Andrea Erxleben B. Lippert 《Journal of biological inorganic chemistry》1997,2(2):256-264
The analogy between H-bonded nucleobase pairs and their metalated analogues is extended to the hemiprotonated pair of 7,9-dimethylguanine
(7,9-DimeG) and the Watson-Crick and reversed Watson-Crick pair between 7,9-dimethylguaninium (7,9-DimeGH+) and 1-methylcytosine (1-MeC). The crystal structure analyses of two model compounds, trans–[Pt(CH3NH2)2(7,9-DimeG-N1)2](NO3)2 (1) and trans–[Pt(NH3)2(1-MeC-N3)(7, 9-DimeG-N1)](PF6)2· 2.5 H2O (3a) are reported. Pt binding is through N1 of 7,9-DimeG and N3 of 1-MeC. In solution, 3a exists in a mixture with Watson-Crick and reversed Watson-Crick arrangements of the two bases, depending on solvent, concentration
and anions.
Received: 16 October 1996 / Accepted: 27 January 1997 相似文献
84.
Dall'Olio Fabio; Mariani Erminia; Tarozzi Andrea; Meneghetti Alessandra; Chiricolo Mariella; Lau Joseph T. Y.; Facchini Andrea 《Glycobiology》1997,7(4):507-513
The extent of processing of N-linked oligosaccharides and thesialylation of the target cell membranes has been positivelycorrelated with resistance to lysis mediated by NK cells, buta conclusive evidence has never been reached. Colon cancer tissuesexpress an increased activity of ß-ga-lactoside 相似文献
85.
Blackburn Alexia Schmitt Andrea Schmidt Peter Wanke Rudiger Hermanns Walter Brem Gottfried Wolf Eckhard 《Transgenic research》1997,6(3):213-222
To characterize long-term actions and interactions of growth hormone (GH) and insulin-like growth factor-II (IGF-II) on postnatal body and organ growth, hemizygous phosphoenolpyruvate carboxykinase (PEPCK)-human IGF-II transgenic mice were crossed with hemizygous PEPCK-bovine GH transgenic mice. The latter are characterized by two-fold increased serum levels of IGF-I and exhibit markedly increased body, skeletal and organ growth. Four different genetic groups were obtained: mice harbouring the IGF-II transgene (I), the bGH transgene (B), or both transgenes (IB), and non- transgenic controls (C). These groups of mice have previously been studied for circulating IGF-I levels (Wolf et al., 1995a), whereas the present study deals with body and organ growth. Growth curves (week 3 to 12) were estimated by regression with linear and quadratic components of age on body weight and exhibited significantly (p < 0.001) greater linear coefficients in B and IB than in I and C mice. The linear coefficients of male I and C mice were significantly (p < 0.001) greater than those of their female counterparts, whereas this sex-related difference was absent in the bGH transgenic groups. The weights of internal organs as well as the weights of abdominal fat, skin and carcass were recorded from 3.5- to 8- month-old mice. In addition, organ weight-to-body weight-ratios (relative organ weights) were calculated. Except for the weight of abdominal fat, absolute organ weights were as a rule significantly greater in B and IB than in I and C mice. IGF-II overproduction as a tendency increased the weights of kidneys, adrenal glands, pancreas and uterus both in the absence and presence of the bGH transgene. Analysis of relative organ weights demonstrated significant (p < 0.05) effects of elevated IGF- II on the relative growth of kidneys (males and females) and adrenal glands (females), confirming our previous report on organ growth of PEPCK-IGF-II transgenic mice. In females, IGF-II and GH overproduction were additive in stimulating the growth of spleen and uterus, providing evidence for tissue-specific postnatal growth promoting effects by IGF-II in the presence of elevated IGF-I 相似文献
86.
Characterization of a Small Family (CAIII) of Microsatellite-Containing Sequences with X-Y Homology 总被引:4,自引:0,他引:4
Patrizia Malaspina Bianca Maria Ciminelli Luigi Viggiano Carla Jodice Fulvio Cruciani Piero Santolamazza Daniele Sellitto Rosaria Scozzari Luciano Terrenato Mariano Rocchi Andrea Novelletto 《Journal of molecular evolution》1997,44(6):652-659
Four X-linked loci showing homology with a previously described Y-linked polymorphic locus (DYS413) were identified and characterized.
By fluorescent in situ hybridization (FISH), somatic cell hybrids, and YAC screening, the X-linked members of this small family
of sequences (CAIII) all map in Xp22, while the Y members map in Yq11. These loci contribute to the overall similarity of
the two genomic regions. All of the CAIII loci contain an internal microsatellite of the (CA)n type. The microsatellites display extensive length polymorphism in two of the X-linked members as well as in the Y members.
In addition, common sequence variants are found in the portions flanking the microsatellites in two of the X-linked members.
Our results indicate that, during the evolution of this family, length variation on the Y chromosome was accumulated at a
rate not slower than that on the X chromosome. Finally, these sequences represent a model system with which to analyze human
populations for similar X- and Y-linked polymorphisms.
Received: 29 July 1996 / Accepted: 15 January 1997 相似文献
87.
Andrea Robitzki Alexandra Mack Arnaud Chatonnet Paul G. Layer 《Journal of neurochemistry》1997,69(2):823-833
Abstract: The function of the enzyme butyrylcholinesterase (BChE) in the developing and mature brain is still unclear. We have inserted 577 bp of the 5' upstream region plus 106 bp of the exon 1 of the rabbit BChE gene in reverse orientation under control of an SV40 early promoter derivative in an expression vector. This vector was introduced by calcium phosphate-mediated transfection into embryonic chicken retina cells during the first days of reaggregation culture. Depending on the retinal origin, the transfected cell population forms histotypic retina-like spheres, so-called rosetted or stratified retinospheroids. We show that antisense 5'-BChE gene expression decreased the steady-state mRNA level of BChE and the translation of the BChE protein, inhibited proliferation, and accelerated histogenesis in both cellular systems. The pronounced effects of antisense 5'-BChE transfection of spheroids document a key role of BChE during the early reaggregation process of retinal cells, most likely by regulating their growth and differentiation. 相似文献
88.
Lun He Kurt J. Isselbacher Jack R. Wands Howard M. Goodman Chiaho Shih Andrea Quaroni 《In vitro cellular & developmental biology. Plant》1984,20(6):493-504
Summary A human hepatocellular carcinoma cell line (FOCUS—Friendship of China and United States) was derived from a patient with primary
hepatocellular carcinoma. This cell line has been in continuous culture over an 18-mo period. The morphological and ultrastructural
features of FOCUS are consistent with its neoplastic hepatocellular orgin. FOCUS cells contain aspartate aminotransferase
and glucose-6-phosphatase activity. In addition, α1-antitrypsin, fibrinogen, alpha fetoprotein, and carcinoembryonic antigens were detectble in the cytoplasm of the cultured
cells by immunochemical staining techniques. The karyotype of the FOCUS cell is human in origin and it contains human DNA
sequences as detected by molecular hybridization analysis. The FOCUS cells do not show evidence of density-dependent inhibition
of growth under confluent conditions. Repeated growth curves over an 18-mo period were identical, revealing a doubling time
of 42 to 48 h. The malignant potential of FOCUS cells was further demonstrated by their ability to lead to gross tumor formation
after subcutaneous infection into nude mice. From one of the solid tumors grown in nude mice, recultured cell lines have been
established and found to have properties identical to the original FOCUS cell line. This FOCUS cell line represents an additional
model for further investigation of tumor specific antigens and the relationship between hepatitis B virus (HBV) and hepatocellular
carcinoma. Preliminary molecular characterization has indicated the existence of integrated HBV sequences within the FOCUS
genome. 相似文献
89.
90.
Summary
D. melanogaster males of
bb/O genetic constitution undergoing rDNA magnification were mated singly to XXbb
+/O females, yielding
bb/O male progeny, and to XNO-w sn bb
+ fameles, yielding
bb/XNO- females. The male and female offspring were scored for the bb
+ phenotype.Results show that there is a higher percentage of bb
+ flies in the
bb/O male progeny than in
bb/XNO- females progeny, in single crosses as well as in the combined data. rRNA/DNA hybridization experiments agree with this observation, by showing that the rDNA content in the progeny of premagnified flies was higher in the sons than in the daughters.These data indicate that the increase of ribosomal RNA genes is not due to a stable event such as an unequal mitotic sister exchange, whereas they do not contrast with the extracopy model. 相似文献