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91.
Human papilloma virus E6/E7 genes can expand the lifespan of human corneal fibroblasts 总被引:2,自引:0,他引:2
Donna M. Peters Nathan Dowd Curtis Brandt Teresa Compton 《In vitro cellular & developmental biology. Animal》1996,32(5):279-284
Summary Human corneal fibroblasts were infected with a retroviral delivery vector containing the E6 and E7 genes from human Papilloma
virus type 16 in order to produce cell lines that have an expanded lifespan in culture. Morphologically, some of the trasfected
corneal fibroblast lines appeared to have the normal spindle-shape morphology of diploid fibroblasts, whereas other lines
appeared to have a more elongated morphology. All the cell lines were anchorage-dependent. Cells that had a normal morphology
grew at a rate similar to normal diploid human corneal fibroblasts and had a population doubling time of 48 h. All E6/E7 expressing
cell lines, regardless of morphology, produce types I, III, and V collagen, at levels similar to those observed in the parent
corneal diploid fibroblast. These corneal fibroblast lines will be a usefulin vitro system to study collagen expression and fibril formation, as well as normal stroma development. These results also demonstrate
that the use of E6/E7 genes to expand a cell’s lifespan can be a powerful tool because it does not appear to alter either
the growth rate of the cell or collagen expression. 相似文献
92.
Human immunodeficiency virus type 1 envelope protein does not stimulate either prostaglandin formation or the expression of prostaglandin H synthase in THP-1 human monocytes/macrophages. 下载免费PDF全文
R Hui J F Curtis M T Sumner S B Shears W C Glasgow T E Eling 《Journal of virology》1995,69(12):8020-8026
Prostaglandin E2 is observed at elevated levels during human immunodeficiency virus (HIV) infection and thus may contribute to the HIV-dependent immunosuppression. The mechanisms responsible for this increase are not understood. Evidence indicates that the viral envelope proteins perturb membrane signaling mediated by the CD4 receptor, suggesting that the free envelope protein and/or the intact virus may be responsible for the increase in prostaglandin E2 levels. In this study, we have used THP-1 human monocytes and THP-1 cells differentiated by 12-O-tetradecanoylphorbol-13-acetate treatment into macrophages to determine if the HIV envelope protein, gp120, or an anti-CD4 receptor antibody stimulates prostaglandin formation by interacting with the CD4 receptor. Incubation of THP-1 cells with OKT4A antibody greatly stimulated the CD4-p56lck receptor complex as estimated by enhanced p56lck autophosphorylation, while the gp120 gave small but significant responses. Monocytic THP-1 cells poorly metabolized arachidonic acid to prostaglandin E2 and thromboxane B2 as measured by high-pressure liquid chromatography analysis. Western blot (immunoblot) and Northern (RNA) blot analyses revealed that unstimulated monocytes expressed little prostaglandin H synthase 1 and 2 (PGHS-1 and -2). Incubation of the monocytes with lipopolysaccharide, OKT4A, or gp120 did not increase the formation of prostaglandins. The expression of PGHS-1 or PGHS-2 was also not increased. Differentiation of the monocytes to macrophages by 12-O-tetradecanoylphorbol-13-acetate treatment resulted in increased expression of PGHS-1 and increased formation of prostaglandins compared with that for the monocytes. Lipopolysaccharide stimulation of the macrophages increased the formation of prostaglandins and increased the expression of PGHS-2 in the macrophages. However, OKT4A or gp120 preparation, at concentrations that stimulated p56lck autophosphorylation, did not enhance the formation of prostaglandins or the expression of PGHS-1 or PGHS-2. OKT4A and gp120 also did not stimulate the release of arachidonic acid, indicating that phospholipase A2 was not activated by the CD4 receptor in either the THP-1 monocytes or macrophages. These results indicate that activation of the CD4-p56lck receptor signal transduction pathway by the HIV envelope protein does not increase prostaglandin formation. 相似文献
93.
Curtis W. Adams Oliver Nanassy Reid C. Johnson & Kelly T. Hughes 《Molecular microbiology》1997,24(6):1235-1247
The Hin recombinase mediates the site-specific inversion of a segment of the Salmonella chromosome between two flanking 26 bp hix DNA recombination sites. Mutations in two amino acid residues, R43 and R69 of the catalytic domain of the Hin recombinase, were identified that can compensate for loss of binding resulting from elimination of certain major and minor groove contacts within the hix recombination sites. With one exception, the R43 and R69 mutants were also able to bind a hix sequence with an additional 4 bp added to the centre of the site, unlike wild-type Hin. Purified Hin mutants R43H and R69C had both partial cleavage and inversion activities in vitro while mutants R43L, R43C, R69S, and R69P had no detectable cleavage and inversion activities. These data support a model in which the catalytic domain plays a role in DNA-binding specificity, and suggest that the arginine residues at positions 43 and 69 function to position the Hin recombinase on the DNA for a step in the recombination reaction which occurs either at and/or prior to DNA cleavage. 相似文献
94.
95.
Restriction fragment length polymorphism analysis, using peroxidase, O-methyltransferase, phenylalanine ammonia-lyase, and coniferyl alcohol dehydrogenase cDNAs isolated from Stylosanthes humilis, as probes, provided molecular evidence for the genetic origin of the naturally occuring allotetraploid genotype Stylosanthes hamata cv. Verano (2n = 4x = 40). Hybridization patterns strongly suggest that the likely progenitors of S. hamata cv. Verano were a diploid S. humilis (2n = 2x = 20) and a diploid S. hamata (2n = 2x = 20) species. 相似文献
96.
D R Curtis R Malik 《Proceedings of the Royal Society of London. Series B, Containing papers of a Biological character. Royal Society (Great Britain)》1984,223(1230):25-33
Although GABA and piperidine-4-sulphonic acid depolarize I a afferent terminations in the cat spinal cord by activation of bicuculline-sensitive GABA receptors, no evidence was obtained for a bicuculline-sensitive alteration by either gabamimetic of the electrical threshold of rubrospinal terminations in the spinal intermediate nucleus. The terminal axonal arborizations in the spinal cord of neurons in the red nucleus thus do not have GABA receptors similar to those on the cell bodies. The results are discussed in relation to the depolarizing action of GABA on some central neurons, and on neurons with peripheral cell bodies, and to probable differences in the intracellular chloride content of neurons having peripheral or central cell bodies, and thus of different embryological origin. A presynaptic depolarizing inhibitory process mediated by GABA appears to be confined to the terminals of primary afferent fibres in the mammalian central nervous system. 相似文献
97.
The effect of enzymatic lipid peroxidation on the molecular order of microsomal membranes was evaluated by ESR spectroscopy using the spin probes 5-, 12-, and 16-doxyl-stearic acid. Rat liver microsomal membranes were peroxidized by the NADPH-dependent reaction in the presence of the chelate ADP-Fe3+. Peroxidation resulted in a preferential depletion of polyenoic fatty acids and an increase in the percentage composition of shorter fatty acyl chains. There was no change in the cholesterol/phospholipid ratio of the peroxidized microsomes. The molecular order of both control and peroxidized membranes decreased toward the central region of the bilayer, and the order parameter (S) of each probe was temperature dependent. Peroxidation of the microsomal membrane lipids resulted in an increase in the order parameter determined with the three stearic acid spin probes. Of the three probes, 12-doxylstearic acid was the most sensitive to the changes in membrane organization caused by peroxidation. These data indicate that ESR spectroscopy is a sensitive method of detecting changes in membrane order accompanying peroxidation of membrane lipids. 相似文献
98.
Roy W. Curtis 《Journal of Plant Growth Regulation》1984,3(1-3):157-168
The biological activities of methyl jasmonate, ABA, methyl abscisate, and malformin were compared in a variety ofVigna radiata abscission tests. Although each compound diminished or completely negated the antiethylene properties of Ag+, differences in potency were observed. ABA and ABA-Me stimulated leaf abscission in the dark, potentiated abscission with low concentrations of ethephon, and interacted synergistically with malformin, whereas methyl jasmonate was inactive in each of these tests. Methyl jasmonate was most active in potentiating leaf abscission induced by high ethephon concentrations and stimulated petiole abscission, whether applied proximally or distally, from debladed explants. In two tests, negation of Ag+ activity and interaction with malformin, ABA concentrations as low as 0.1 M were biologically active and indicated that ABA can be a highly active abscission-inducing compound. Based on differences in biological activity, it was concluded that the modes of action of methyl jasmonate, ABA, and malformin were different.Journal Paper No. 9811 of the Purdue Agricultural Experiment Station. 相似文献
99.
James C. Willey Clementh E. Moser Jr. Curtis C. Harris 《Cell biology and toxicology》1984,1(1):145-154
The effects of aplysiatoxin and debromoaplysiatoxin on the clonal growth rate, cross-linked envelope formation and plasminogen activator secretion of normal human bronchial epithelial cells were studied. Neither compound was mitogenic over a wide range of concentrations (10–13 to 10–7M). Both aplysiatoxin and debromoaplysiatoxin inhibited clonal growth rate with 50% inhibitory concentrations of 3 × 10–11M and 10–10M, respectively. Both compounds induced the formation of cross-linked envelopes and increased plasminogen activator secretion with equal potency. These data are similar to those previously obtained with 12-0-tetradecanoylphorbol-13-acetate and teleocidin B and suggest that aplysiatoxin and debromoaplysiatoxin induce terminal squamous differentiation in normal human bronchial epithelial cells.Abbreviations TPA
12-0-tetradecanoylphorbol-13-acetate
- NHBE
Normal Human bronchial epithelial
- ID50
50% inhibitory concentration (dose)
- PA
Plasminogen activator
- CLE
Cross-linked envelope
- LHC
Laboratory of Human Carcinogenesis 相似文献
100.
Segregation of Cytoplasmic Incompatibility Properties in CULEX PIPIENS FATIGANS 总被引:2,自引:2,他引:0 下载免费PDF全文
Sarala K. Subbarao B. S. Krishnamurthy C. F. Curtis T. Adak R. K. Chandrahas 《Genetics》1977,87(2):381-390
Maternally inherited variants, which arose within a laboratory colony of Culex pipiens fatigans, have been studied by rearing cultures from single egg rafts. Segregation, i.e, variation of cytoplasmic incompatibility properties between the male progeny of individual females, was demonstrated. Also, from the daughters of individual females, sub-lines were derived within which all the males showed the same incompatibility or compatibility properties. Among the descendants of tetracycline-treated individuals were lines which superficially simulated these phenomena, but theses lines ultimately reverted to the cytoplasmic compatibility type of the strain which was submitted to the treatment. The types of variation s in cytoplasmic incompatibility properties that have been studied are discussed. 相似文献