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61.
C Capdeville F el Bouhtoury R M Parache R G Boulu J Guillou J Atkinson 《Life sciences》1990,47(6):539-546
Global cerebral ischemia (four vessel model) was induced in renovascular hypertensive rats (two kidney, one clip model) chronically treated with intraperitoneal administration of angiotensin I converting enzyme inhibitors, either captopril (100 mg/kg per day) or Wy-44,655 (10 mg/kg per day). Mortality following cerebral ischemia was higher in renovascular hypertensive rats than in normotensive controls. Reduction of blood pressure with captopril or Wy-44,655, lowered mortality. In surviving renovascular hypertensive and normotensive rats cerebral ischemia induced hyperactivity and lesions of the CA1 area of the hippocampus. Prolonged treatment with captopril--but not with Wy-44,655--reduced hyperactivity and the extent of the CA1 lesions. In conclusion, hypertension increases mortality following cerebral ischemia but does not affect the extent of brain injury in survivors. Prior treatment with converting enzyme inhibitors lowers mortality. Treatment with captopril attenuates brain injury in survivors. 相似文献
62.
Arachidonic acid, cellulase, CuSO4, a sonicate of Phytophthora infestans mycelium and a spore suspension of Penicillium chrysogenum all elicited the formation of the sesquiterpenoid phytoalexins lubimin, 3-hydroxylubimin and rishitin in fruit cavities of Datura stramonium. 3-Hydroxylubimin was the predominant phytoalexin formed after treatment of the fruits with arachidonic acid, cellulase and the P. infestans preparation. Copper sulphate was a potent elicitor of lubimin but not 3-hydroxylubimin. The fungus P. chrysogenum metabolized lubimin and 3-hydroxylubimin to 15-dihydrolubimin and 3-hydroxy-15-dihydrolubimin respectively, both in fruit cavities inoculated with spores of this fungus and in pure culture. The 15-dihydrolubimin formed in the fruits by the fungus was further metabolized (by the fruits) to both isolubimin and 3-hydroxy-15-dihydrolubimin. The precursor-product relationships between all of the subject compounds was investigated by feeding experiments with 3H-labelled compounds. 2-Dehydro-[15-3H1]lubimin was rapidly and efficiently incorporated into lubimin and may be the direct precursor of lubimin in planta. 3-Hydroxy[2-3H1]lubimin was incorporated into the nor-eudesmane rishitin but 10-epi-3-hydroxy[2-3H1]lubimin was not. An updated scheme for the biosynthesis and metabolism of lubimin and related compounds in infected tissues of solanaceous plants is presented.We thank Mr Vic Swetez for the provision of plant material, Mrs Margaret Huffee for technical assistance, Dr David Ewing for help with obtaining NMR spectra, and the Agricultural and Food Research Council for financial support. 相似文献
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65.
Syringolide 1 Triggers Ca2+ Influx,K+ Efflux,and Extracellular Alkalization in Soybean Cells Carrying the Disease-Resistance Gene Rpg4 总被引:1,自引:0,他引:1 下载免费PDF全文
Alleles of avirulence gene D (avrD) specify the production by bacteria of syringolides that elicit the hypersensitive response in soybean (Glycine max) plants carrying the disease-resistance gene Rpg4, but not rpg4 plants. Syringolide 1 caused extracellular alkalization, K+ efflux, and Ca2+ influx about 30 min after addition to suspension-cultured cells of two Rpg4 cultivars, Harosoy and Flambeau, but not in two rpg4 cultivars, Acme and Merit. All responses were sustained for at least 1.5 h and were inhibited by La3+, which blocks certain Ca2+ channels. These results suggest that syringolide 1 activates a Ca2+ influx-dependent signaling pathway only in Rpg4 soybean cells. 相似文献
66.
Richard L. Atkinson Roy C. Blank Judy F. Loper Donald Schumacher Richard A. Lutes 《Obesity (Silver Spring, Md.)》1995,3(Z4):497S-500S
Pharmacological treatment of obesity has been neglected as a viable therapeutic option for many years. Recent long term studies with combinations of obesity drugs gives promise that drugs may play a role in weight maintenance, which classically has been the most difficult aspect of treating obesity. Currently available obesity drugs include centrally acting adrenergic agents and serotonin agonists. Drugs still in development include a lipase inhibitor that produces fat malabsorption, a combined adrenergic-serotonergic reuptake inhibitor, various gut-central nervous system peptides, and a number of beta-3 agonists. Any of these obesity drugs given alone produces modest weight loss, and for most, weight loss continues for as long as medication is given. The most successful drug regimens to date are combinations of phentermine and fenfluramine or of ephedrine, caffeine, and/or aspirin. The former combination produces reduction in body weight and complications of obesity for 2 to almost 4 years in clinical trials to date. More research is needed to document long term efficacy and particularly the long term safety of these and other combinations. 相似文献
67.
Effect of tumor necrosis factor-α and interferon-γ on the growth of a human salivary gland cell line
Ava J. Wu Regina H. Kurrasch Joseph Katz Philip C. Fox Bruce J. Baum Jane C. Atkinson 《Journal of cellular physiology》1994,161(2):217-226
Interferon-γ (IFN-γ) is a product of activated T-lymphocytes, and tumor necrosis factor-α (TNF-α) is a product of both lymphocytes and macrophages. These cell types are often present at sites of tissue damage secondary to chronic infection or autoimmune disease. The purpose of this study was to characterize the effects of TNF-α and IFN-γ on a human submandibular gland epithelial cell line (HSG). IFN-γ caused a concentration-dependent decrease in HSG cell growth (~70% in 6 days). Conversely, TNF-α alone had little effect on the growth of these cells. When these cytokines were added in combination (20 units/ml TNF-α and 1,000 units/ml of IFN-γ), there was a synergistic antiproliferative effect; no apparent cell growth was observed. The cytokine-induced antiproliferative effect was reversible. After the apparent cessation of cell growth for 3–6 days, removal of the cytokines permitted complete growth recovery. Further, cells that recovered and exhibited growth patterns that were similar to control cells remained susceptible to the antiproliferative effects of the cytokines. Flow cytometry revealed that the percentage of cells in G0/G1 with the combination of cytokines was significantly increased by 24 h. The antiproliferative effect of IFN-γ alone and that of IFN-γ and TNF-α in combination were blocked completely using an antibody to the IFN-γ receptor. A hypothesized mechanism of tissue damage in autoimmune inflammatory disorders is via up-regulation of cell surface markers such as intercellular adhesion molecule type I (ICAM-1) and histocompatibility antigen HLA-DR which can exacerbate the inflammatory process. Treatment of HSG cells with IFN-γ, with or without TNF-α, resulted in increased levels of ICAM-1 and the acquisition of HLA-DR expression. These aggregate data suggest that IFN-γ alone can regulate the expression of cell surface markers involved in the inflammatory process as well as cause a potent yet reversible inhibition of HSG cell growth that is modulated by the presence of TNF-α. © 1994 Wiley-Liss, Inc. 1 This article is a US Government work and, as such, is in the public domain in the United States of America. 相似文献
68.
Binding of measles virus to membrane cofactor protein (CD46): importance of disulfide bonds and N-glycans for the receptor function. 总被引:16,自引:12,他引:4 下载免费PDF全文
A Maisner J Schneider-Schaulies M K Liszewski J P Atkinson G Herrler 《Journal of virology》1994,68(10):6299-6304
Two cellular proteins, membrane cofactor protein (MCP) and moesin, were reported recently to be functionally associated with the initiation of a measles virus infection. We have analyzed the interaction of measles virus with cell surface proteins, using an overlay binding assay with cellular proteins immobilized on nitrocellulose. Among surface-biotinylated proteins from a human rectal tumor cell line (HRT), measles virus was able to bind only to a 67-kDa protein that was identified as MCP. The virus recognized different isoforms of MCP expressed from human (HRT and HeLa) and simian (Vero) cell lines. The binding of measles virus to MCP was abolished after cleavage of the disulfide bonds by reducing agents as well as after enzymatic release of N-linked oligosaccharides. By contrast, removal of sialic acid or O-linked oligosaccharides did not affect the recognition of MCP measles virus. These data indicate that the receptor determinant of MCP is dependent on a conformation of the protein that is maintained by disulfide bonds and N-glycans present in the complement binding domains. Our results are consistent with a role of MCP as primary attachment site for measles virus in the initial stage of an infection. The functional relationship between MCP and moesin in a measles virus infection is discussed. 相似文献
69.
The functional units of a peptostreptococcal protein L 总被引:4,自引:0,他引:4
Jonathan P. Murphy Clive J. Duggleby Max A. Atkinson † Angus R. Trowern Tony Atkinson Christopher R. Goward 《Molecular microbiology》1994,12(6):911-920
Protein L is a cell-surface protein from Peptostreptococcus which interacts with immunoglobulin kappa light chains. A gene from Peptostreptococcus strain 3316 coding for protein L and fragments thereof were expressed in Escherichia coli. The peptides were examined for binding to immunoglobulin and serum albumin. The four C units were shown to be responsible for binding to immunoglobulin and the four D units for binding to albumin. This protein L molecule therefore binds to albumin at a site separate from that involved in binding to immunoglobulin. The albumin-binding units have high amino acid sequence identity with the albumin-binding units of streptococcal cell-surface proteins. The gene contains three sites available for internal initiation of translation resulting in three active proteins. The protein L molecule presented in this report was compared with a previously reported protein from Peptostreptococcus strain 312. The two proteins differ in several respects, including size and the number and types of repeat units. 相似文献
70.
Using standard hybridoma technology and hierarchical screening, monoclonal antibodies (MAbs) were obtained with specific reactivity against two developmental stages of Globodera pallida. The procedure was based on enzyme-linked immunosorbent assay (ELISA) with homogenates prepared from second-stage juveniles, young adult females, and potato roots. Hybridomas were formed by fusing myelomas with splenocytes derived from mice immunized with either infective juveniles or females of G. pallida. About 600 hybridoma lines were screened from the fusion involving the mouse immunized with juveniles. Two MAbs (LJMAbl &2) were identified with high reactivity toward second-stage juveniles but no reactivity with either potato roots or females of G. pallida. A total of 630 cell lines was screened from the corresponding fusion involving the spleen of a mouse receiving immunogens from adult female nematodes. One MAb (LFMAbl) was obtained with the required specificity against only adult female G. pallida. This work extends the application of monoclonal antibodies in nematology from valuable probes for research and species identification to recognition of developmental stages. These specific MAbs have potential value in plant breeding programs for screening for resistant lines unable to support nematode development. 相似文献