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2.
W A Pryor 《Free radical biology & medicine》1987,3(3):189-191
In the Forum that follows, four authorities in nutrition and vitaminology present their divergent views on the use of antioxidant vitamin supplements. In this introduction, the basic dilemma between setting RDAs that insure an absence of deficiency symptoms and those that insure optimal health is discussed, as well as other factors that must be considered to reach a consensus on this controversial topic. 相似文献
3.
Isolation of a flax (Linum usitatissimum) gene induced during susceptible infection by flax rust (Melampsora lini) 总被引:2,自引:0,他引:2
In a susceptible infection of flax ( Linum usitatissimum ), the obligate rust pathogen ( Melampsora lini ) can grow in the leaf without triggering the hypersensitive resistance response. The rust establishes specialized structures (haustoria) in plant mesophyll cells and induces changes in plant subcellular organization. Subtraction hybridization methods were used to isolate cDNA clones of mRNAs that have altered expression in infected leaves. Most of the cDNAs recovered were of fungal origin, but one clone, pFIS1 ( f lax i nducible s equence No. 1), recovered from several independent experiments, was a plant-specified mRNA that showed a 10-fold increase in steady-state levels during susceptible growth. The increase in fis1 mRNA levels was not seen in the resistant reaction (hypersensitive reaction) and the predicted protein sequence (551 amino acids with a predicted molecular weight of 61 kDa) has no similarity to known pathogenesis-related proteins. Searches of sequence data bases showed that fis1 encodes a protein which contains amino acid sequence motifs that are conserved in all previously characterized aldehyde dehydrogenases. 相似文献
4.
Effects of slitting the zona pellucida and its subsequent sealing on freeze-thaw survival of Day 7 bovine embryos 总被引:1,自引:0,他引:1
The effects of slitting the zona pellucida and its subsequent sealing by either embedding in agar or surrounding with an additional zona pellucida on the development of frozen/thawed Day 7 bovine embryos were investigated in vitro and in vivo. A total of 225 embryos was frozen and thawed rapidly as controls (Group 1), after slitting the zona pellucida (Group 2), after slitting and subsequent sealing of the zona pellucida with agar (Group 3), or after slitting the zona pellucida (Grothen transferring the embryo into an additional zona pellucida (Group 4). The survival rate (embryos classified morphologically as excellent, good, or poor) was 95.1, 95.4, 92.2, and 94.3% for Groupsl, 2, 3, and 4, respectively. Culture of 145 embryos in vitro for 60 h revealed that 57.1, 59.5, 47.4, and 57.1% developed to hatching and hatched blastocysts in Groups 1, 2, 3, and 4, respectively. Within Group 3, however, a significantly (P < 0.05) lower percentage of the embryos continued to develop when the agar was not removed after thawing (31.8%) compared with embryos from which the agar had been removed (68.8%). After nonsurgical transfer of 78 embryos, the pregnancy rate was significantly (P < 0.05) lower (8.3%) with embryos of Group 3 compared with controls (61.5%) or embryos of Group 2 (42.9%). No significant difference existed between controls and embryos of Group 2. We conclude that an intact zona pellucida prior to rapid freezing is not essential for the survival of Day 7 bovine embryos. 相似文献
5.
T Yoshikawa W Flory D H Giamalva L P Ruhr D F Church W A Pryor 《Biochemistry international》1987,15(1):147-151
Male Sprague-Dawley rats were treated ip with beta-naphthoflavone (40 mg/kg/day) in corn oil or in DMSO for three days. Diphenaldehyde (90 mg/kg in DMSO) was injected ip 24 hr after pretreatment. The increase in the levels of aspartate aminotransferase, alanine aminotransferase, sorbitol dehydrogenase, gamma glutamyl transpeptidase, and lactate dehydrogenase was significantly lower in rats pretreated with BNF. This suggests that the BNF-induced P-450 isozyme systems have a protective effect against the acute hepatotoxicity of diphenaldehyde. 相似文献
6.
Potassium-mediated stimulation of hepatic glycogenolysis 总被引:1,自引:0,他引:1
Increased extracellular potassium concentrations ([K+]o) stimulated transient increases in glucose release and 45Ca2+ washout in the perfused rat liver. Stimulated glucose release had a K0.5 of about 26 mM for [K+]o, was not desensitized by successive infusion intervals of increased [K+]o, was not affected by altering the direction of perfusion, was absolutely dependent on the presence of [Ca2+]o, and was blocked by 2 mM cobalt or 10 microM verapamil. The increase in 45Ca2+ washout resulting from increased [K+]o also was blocked by 2 mM cobalt or 10 microM verapamil. Inhibitors of vascular tone (nitroprusside, atriopeptin II), arachidonic acid metabolism (indomethacin, nordihydroguaiaretic acid), and alpha- or beta-adrenergic or muscarinic nerve stimulation/secretion (phentolamine, propranolol, atropine) were unable to inhibit the [K+]o-stimulated glucose release. ATP, ADP, and AMP concentrations in tissue freeze-clamped 2 min after the onset of infusion of 50 mM K+ were not significantly different from control tissue. Glucose release from freshly isolated suspensions or primary cultured monolayers of hepatocytes or from liver slices, all of which responded to glucagon or phenylephrine, did not respond to increased [K+]o. The results indicate that glycogenolysis stimulated by depolarizing gradients of K+ is dependent on an intact perfused vasculature and may be mediated by potential-sensitive Ca2+ channels present in the vascular endothelium of the liver. 相似文献
7.
T Yoshikawa W Flory D H Giamalva L P Ruhr D F Church W A Pryor 《Biochemistry international》1988,16(5):929-934
Male Sprague-Dawley rats were pretreated i.p. with corn oil or DMSO (1.5 ml/kg/day), or with beta-naphthoflavone (BNF, 40 mg/kg/day) in corn oil or DMSO for 3 days. 1-Nitropyrene (1-NP, 150 mg/kg) in DMSO was injected i.p. 24 hr after pretreatment. A significant increase in the levels of several serum enzymes was seen in rats pretreated with corn oil alone 24 hr after 1-NP injection. The increase in enzyme activities was significantly reduced by a 3-day pretreatment with DMSO or BNF. 相似文献
8.
The effects of dietary (n-3) fatty acid supplementation on lipid dynamics and composition in rat lymphocytes and liver microsomes 总被引:1,自引:0,他引:1
D M Conroy C D Stubbs J Belin C L Pryor A D Smith 《Biochimica et biophysica acta》1986,861(3):457-462
Rats were fed diets devoid of (n-3) fatty acids (olive oil supplementation) or high in (n-3) fatty acids (fish oil supplementation) for a period of 10 days. In spleen lymphocytes and liver microsomes derived from animals fed fish oil diets, relatively high levels of (n-3) eicosapentaenoic (20:5), docosapentaenoic (22:5) and docosahexaenoic acids (22:6) were obtained compared to minimal levels when fed the olive oil diet. When the average lipid motional properties were examined by measuring the fluorescence anisotropy of diphenylhexatriene, no significant different was found between intact liver microsomes from animals fed the two diets. However, when lipid motion was examined in vesicles of phosphatidylcholine, isolated from the microsomes from fish oil fed animals (21.4% (n-3) fatty acids), the fluorescence anisotropy was significantly less than the corresponding phosphatidylcholine from olive oil fed animals (5.6% (n-3) fatty acids), indicating a more disordered or fluid bilayer in the presence of higher levels of (n-3) fatty acids. Phosphatidylethanolamine (n-3) fatty acids were also elevated after fish oil supplementation (41.3% of total fatty acids), compared to the level after olive oil supplementation (21.4%). The major effect of the fish oil supplementation was a replacement of (n-6) arachidonic acid by the (n-3) fatty acids and when this was 'modeled', using liposomes of synthetic lipids, 1-palmitoyl-2-arachidonyl(n-6) or docosahexaenoyl(n-3)-phosphatidylcholine, significant differences in lipid motional properties were found, with the docosahexaenoate conferring a more disordered or fluid lipid environment. Thus it appears that although lipid order/fluidity can be significantly decreased by increases in the highly unsaturated (n-3) fatty acid levels, alterations in membrane domain organization and/or phospholipid molecular species composition effectively compensated for the changes, at least as far as average lipid motional properties in the intact membranes was concerned. 相似文献
9.
A comparison of the rates of ozonation of biological antioxidants and oleate and linoleate esters 总被引:3,自引:0,他引:3
D Giamalva D F Church W A Pryor 《Biochemical and biophysical research communications》1985,133(2):773-779
The rates of reaction with ozone of some biological antioxidants and simple polyunsaturated fatty acids (PUFA) have been measured in water or in aqueous micellar solutions. At pH 7.0 the rate constants are ca. 10(6) M-1 sec-1 for urate, alpha-tocopherol, and PUFA, and 6 X 10(7) M-1 sec-1 for ascorbate. When ozone-containing air is breathed, ascorbate in the lung may undergo direct ozonation. However, alpha-tocopherol is probably spared direct reaction with ozone because it doesn't effectively compete with PUFA in pulmonary membranes; rather, tocopherol is used to scavenge radicals produced from the ozone-PUFA reaction. 相似文献
10.
The effects of dopamine and octopamine on adenylate cyclase activity were studied on the head homogenate of adult Culex pipiens mosquitoes in vitro. Both dopamine and octopamine were shown to increase the cyclic AMP content in the homogenate. The antagonist haloperidol blocked the production of cyclic AMP induced from dopamine but had no effect on the production of cyclic AMP induced by octopamine at the concentrations tested. The opiate agonist etorphine was ineffective at reducing cyclic AMP levels induced by either dopamine or octopamine at the concentrations tested. 相似文献