Search PubMed⌕ Search

Biomedical subjects

F A Green

Publications and source records attributed to F A Green.

At least 37 records · Page 2Linked to original sources
PubMed1989

Lipoxygenase activities of the epithelial cells of the human buccal cavity.

The lipoxygenase activities of cultured human buccal epithelial cells and cells taken ex vivo from the human buccal cavity were compared. Lipoxygenation by cultured cells exhibited exclusively omega-6 positional specificity. A membrane-damaging event such as freezing was required for activation. In contrast, after simple addition of arachidonic acid, the ex vivo buccal cells produced predominantly 12-hydroxyeicosatetraenoic acid. Chromatography on chiral columns yielded products which had an (S) configuration at the site of oxygen insertion. 5-hydroxyeicosatetraenoic acid was transformed by ex vivo buccal cells to 5(S),12(S)-dihydroxyeicosatetraenoic acid. These products could have a role in modulation of inflammatory states of the oral cavity.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1989

Generation and metabolism of lipoxygenase products in normal and membrane-damaged cultured human keratinocytes.

The production and metabolism of lipoxygenase eicosanoids were studied in cultured human keratinocytes. The identity of these eicosanoid structures was established by a variety of chromatographic and analytical techniques. Normal cultured keratinocytes did not produce lipoxygenase eicosanoids either spontaneously or when given arachidonic acid in the presence of permeabilizing concentrations of ethanol or dimethyl sulfoxide. Freeze-thawing of human neonatal and adult keratinocytes resulted in a rapid release of linoleic and arachidonic acids over time. Activation of a latent 15-lipoxygenase was demonstrated by the synthesis of 15-hydroxyeicosatetraenoic acid (15-HETE) and 13-hydroxyoctadecadienoic acid, and both these products were greatly increased in amount when the corresponding fatty acid precursor was added. Eicosanoid production by cells of newborn and adult origin was indistinguishable. Rapid metabolism of exogenous 15-HETE by normal keratinocytes was observed. Measurable quantities of esterified 15-HETE were found after 1 min, but by 18-20 h all the esterified 15-HETE was degraded to the extent that 80% of the recovered radioactivity was found in water-soluble form. In contrast, when labeled or unlabeled 5-HETE was used a much larger fraction was esterified intact (30% as opposed to 10%) and at the end of 18-20 hours a substantial peak of esterified 5-HETE remained. Intact esterified [3H] HETE were recovered only in the triacylglycerol fraction. The key findings that omega-6 lipoxygenase products are generated but not esterified by membrane-damaged keratinocytes, whereas these products are esterified but not generated by normal keratinocytes, may be of importance in transcellular metabolic control.

Adult↗
PubMed1989

Cytochrome P-450 mediated metabolism in active murine systemic lupus erythematosus.

In a comparison of NZB/NZW female mice either with active systemic lupus erythematosus (SLE) (28-33 weeks of age) or without overt SLE (7-13 weeks), the hepatic microsomal activities of ethoxycoumarin O-deethylation and aminopyrine N-demethylation were decreased 32% (p less than 0.05) and 28% (p less than 0.03), respectively, and cytochrome P-450 levels were decreased 34% (p less than 0.01) in the mice with active SLE. These changes were not associated with age differences alone in 2 nonautoimmune strains. Active murine SLE is thus associated with significant depressions in both hepatic cytochrome P-450 levels and microsomal enzyme activities. The metabolism of drugs and endogenous substrates may thus be impaired in active SLE.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1988

Intracellular cold trapping of exogenous arachidonic acid and activation of the 5-lipoxygenase pathway of human neutrophils.

Exogenous arachidonic acid was trapped in human leukocytes with ethanol at 0 degrees C and 16 degrees C. Leukotriene B4 and its isomers were produced from the trapped substrate, and this production continued for at least 24 h at 0 degrees C. Synthesis from trapped substrate of these eicosanoids increased as a function of the incubation temperature. The ability to study leukotriene synthesis and intercellular transfer from exogenous but intracellularly trapped substrate without the multiple effects of cell activators may be of value in elucidating the metabolism and regulatory properties of these lipoxygenase products.

Arachidonate 5-Lipoxygenase↗
PubMed1988

Leukotriene production associated with leukocyte membrane destruction: evidence of a terminal signal.

Four methods of severe disruption of human neutrophil membrane integrity resulted in the formation of substantial amounts of leukotriene B4 and its isomers. This synthesis took place from endogenous substrate in the absence of any cell activators. It is postulated that leukotriene formation could be a preserved cell function and that generation at this stage could constitute a terminal chemotactic signal.

Arachidonic Acids↗
PubMed1988

Suppression of leukotriene synthesis in human leukocytes by a urea extract of Bordetella pertussis: evidence for mediation by adenylate cyclase toxin.

Incubation of human leukocytes with a urea extract of Bordetella pertussis led to inhibition of zymosan-induced leukotriene generation. The proteins in this extract are known to include an adenylate cyclase which suppresses certain defense mechanisms of leukocytes against bacterial invasion. The formation of leukotriene B4 and leukotriene C4, induced by serum-coated zymosan, was almost completely inhibited in the presence of 75 micrograms of urea-extracted proteins/ml cell suspension. This suppression by the bacterial urea extract was rapid, with the maximum effect occurring in the first min of incubation. The reduction in leukotriene generation was accompanied by a dramatic increase in intracellular cyclic AMP levels. Since leukotrienes are potent pro-inflammatory compounds, the present study indicates that Bordetella pertussis-induced suppression of leukotriene formation might be an important factor in the increased susceptibility to secondary bacterial infection, which occurs as a result of this disease.

Adenylate Cyclase Toxin↗
PubMed1988

Binding affinity of serum immunoglobulin G to cardiolipin and other phospholipids in patients with systemic lupus erythematosus and syphilis.

Qualitative and quantitative assays for human antibodies to cardiolipin and other phospholipids were used in tests for these reactions in sera from patients with systemic lupus erythematosus (SLE) and syphilis. Of 22 SLE serum samples tested by the qualitative assay, 8 showed positive staining to cardiolipin, phosphatidic acid, and/or phosphatidylserine. All 47 syphilitic sera reacted with these three phospholipids. The apparent affinity of anticardiolipin binding was estimated by normalizing absolute binding levels as a function of serum concentration to the maximum percent bound. It was evident that antibody affinity was four- to fivefold lower in the SLE sera than in the syphilitic sera. Twelve serum samples from patients with one or more features of the anti-cardiolipin syndrome demonstrated mean binding values which were not distinguishable from binding in other SLE sera. In sera from patients with active SLE, binding affinity for cardiolipin was somewhat greater than that in samples from patients with inactive disease, but the differences were not statistically significant. The low anticardiolipin binding affinity which was observed in patients with SLE compared with that in patients with syphilis casts doubt on a pathogenic role for these reactions.

Adult↗
PubMed1988

Central nervous system lupus erythematosus: the value of magnetic resonance imaging.

Magnetic resonance imaging was sued to examine the brains of 13 patients with systemic lupus erythematosus (SLE) who had experienced symptoms and signs of encephalopathy. All the patients had normal computerized tomographic scans. Four patients with abnormal magnetic resonance imaging studies had active central nervous system disease. None of the 9 patients with normal scans had active nervous system involvement at the time of study. Parenchymal lesions were usually located in the region of the corticomedullary junction or in the deep periventricular white matter. In coronal sections, some of the corticomedullary lesions extended centripetally as thin irregular lines into the white matter approximating the course of penetrating arterioles of the brain. The parenchymal lesions resolved in 4 months in 1 patient, but persisted unchanged in the others despite clinical improvement or a stable clinical course. It is likely that the parenchymal lesions of these patients represent intrinsic vasculopathy of small cerebral vessels and perivascular microinfarctions associated with SLE.

Adult↗
PubMed1987

In vivo generation of 5-lipoxygenase products in frogs and toads.

Eicosanoid production by inflammatory cells which resulted from infection of the peritoneal cavity of Rana catesbeiana and Bufo americanus was studied after addition of exogenous arachidonic acid and for metabolites generated in vivo. From exogenous substrate, the cells of Rana catesbeiana produced substantial amounts of 5-hydroxyeicosatetraenoic acid, leukotriene B4, the non-enzymatic isomers of leukotriene B4 and leukotriene C4. From endogenous substrate, 5-hydroxyeicosatetraenoic acid and leukotriene B4 were produced. Cells from Bufo americanus produced leukotriene B4 and 5-hydroxyeicosatetraenoic acid, from both exogenous and endogenous substrate. These observations of in vivo eicosanoid production confirm the participation of 5-lipoxygenase activity in the inflammatory response to infection.

Animals↗
PubMed1987

Leukotrienes and related eicosanoids are produced by frog leukocytes.

The metabolites of inflammatory cells produced by massive infection of the peritoneal cavity of two related European species of frogs, Rana temporaria and Rana arvalis were examined for lipoxygenase-generated products of exogenous arachidonic acid. Cells of Rana temporaria produced large amounts of 5-hydroxyeicosatetraenoic acid and leukotriene B4. Cells from Rana arvalis produced only 15-hydroxyeicosatetraenoic acid. This is the first unequivocal demonstration of such enzyme activity in lower vertebrates. There was a trend towards increased mortality in the species without evidence of 5-lipoxygenase activity.

Animals↗
PubMed1987

Divalent cation effects on the binding of human anti-phospholipid antibodies.

Anti-phospholipid antibodies from sera of subjects with documented syphilis were measured as a result of their individual interactions with cardiolipin, phosphatidylserine and phosphatidic acid, each impregnated in nitrocellulose paper from chloroform solution, followed by reaction with a labelled second antibody. Binding curves generated by increasing the cardiolipin concentration over a standard area of nitrocellulose paper showed saturation. The presence of Ca2+ or Mg2+ during the antibody binding step resulted in a complex pattern of binding as a function of the cation concentration. When the extent of binding was normalized to percent of maximum bound, virtually super-impossible patterns were seen with different sera. These patterns were distinctive for both the phospholipid and the cation. The speculation is presented, albeit without any direct evidence, that the extent of antibody binding is sensitive to a variety of intermediate phospholipid phase structures which may be initiated by the presence of the specific divalent cation at a particular concentration.

Autoantibodies↗
PubMed1987

Cholesterol effects on the interaction of cardiolipin with anti-cardiolipin antibody.

Human antibodies to cardiolipin, phosphatidic acid and phosphatidylserine were assessed by binding to nitrocellulose paper and subsequent reaction with an enzyme-linked or radioactively labelled second antibody to human IgG. The addition of cholesterol to constant amounts of cardiolipin impregnated in the nitrocellulose paper resulted in a profound fall in antibody binding beginning at a 0.5 to 1 molar ratio of cholesterol to cardiolipin and stabilizing at about 15% of the original level. Antibody binding to phosphatidic acid and phosphatidylserine also showed extensive cholesterol-induced inhibition beginning at a slightly lower molar ratio of cholesterol to phospholipid. The structural array of neither the cardiolipin alone impregnated in nitrocellulose nor the phospholipid together with cholesterol is known. It is possible that the specific cardiolipin phase structure required for human antibody recognition was disrupted by cholesterol.

Autoantibodies↗
PubMed1987

The extracellular control of intracellular aspirin hydrolysis.

We have previously presented evidence that an intra-erythrocyte arylesterase is primarily responsible for the deacetylation of aspirin to salicylate. We now report studies on extracellular control factors. The fractional acetylsalicylic acid (ASA) hydrolysis at the completion of 20-minute incubations in suspensions of washed red blood cells (RBC) with human serum albumin (HSA) decreased sharply, from 0.6 at 0 gm/dl HSA to 0.2 at 5.0 gm/dl HSA. In RBC suspensions with oleic, linoleic, and lauric acid, ASA hydrolysis increased as fatty acid:HSA ratios increased. The addition of salicylate (SA) also resulted in an increase in the fraction hydrolyzed. In a separate, more direct, ultracentrifugation assay, unbound ASA levels were similarly affected by HSA and the other ligands. When SA and oleic acid were incubated with ASA in RBC, additive competition for binding sites was apparent at relatively low levels of the fatty acid. In the presence of increasing concentrations of sodium SA, 5-amino SA, and 4-amino SA, ASA hydrolysis in RBC suspensions was increased by an average of 137%, 75%, and 54%, respectively. The most reasonable explanation for these findings is that the intact ASA molecule binds to albumin and that the binding of competing ligands can modulate the levels of free ASA in the circulation. This, in turn, affects the amount of drug available as substrate for penetration into the RBC and reaction with the intracellular hydrolase which catalyzes ASA deacetylation. Such factors controlling drug availability, if validated in vivo, could be important with regard to the antiinflammatory and anti-platelet properties of aspirin.

Aspirin↗
PubMed1987

Monohydroxyeicosatetraenoic acid and leukotriene production by the inflammatory cells of Xenopus laevis.

Ten frogs (Xenopus laevis) were injected with mixed bacteria to produce a septic peritonitis. Peritoneal inflammatory cells of eight animals were studied for monohydroxyeicosanoid and leukotriene production from exogenous arachidonic acid. Large amounts of 12-hydroxyeicosatetraenoic acid were produced; smaller amounts of 5- and 15-hydroxyeicosatetraenoic and leukotriene B4 were produced. Identifications were confirmed by retention times on HPLC, ultraviolet spectroscopy on all products, and gas chromatograph/mass spectrometry in the case of 12-hydroxyeicosatetraenoic acid.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1987

Lipoxygenase products from polymorphonuclear leukocytes and epithelial cells of human saliva.

Physiological mixtures of salivary cells from 10 volunteers were examined for lipoxygenase products of exogenous arachidonic acid, the intracellular penetrability of which was enhanced by ethanol. Leukotriene B4 and its nonenzymatically produced isomers as well as 5-, 12-, and 15-hydroxyeicosatetraenoic acids (HETE) were produced in all samples. Their identity was confirmed by retention time on reverse-phase high-performance liquid chromatography, ultraviolet spectroscopy, and in the case of 12-HETE, by gas chromatography/mass spectrometry. In order to determine the absolute stereo-chemistry of 12-HETE, its (-)-menthoxycarbonyl derivative was prepared and subjected to oxidative ozonolysis, methylation, and finally gas chromatography. The results indicate that the original configuration is 12(S)-HETE. The production of leukotriene B4 correlated directly with the age of the donor while production of 15-HETE varied inversely with age. Alternative stimulation of lipoxygenase production by ionophore A23187 also resulted in substantial amounts of leukotriene B4 but the amount of 12-HETE produced was less than 2% of the amount generated with the ethanol/arachidonic acid method. This would suggest that 12-HETE production took place predominantly in cells which were not capable of being stimulated by the ionophore. These results point to the epithelial cells, rather than platelets, as the source. The presence of epithelial cells and neutrophils in the saliva, both of which have active lipoxygenase activity, provide the potential for cell interactions of a regulatory nature.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1986

Ethanol-enhanced transmembrane penetration of arachidonic acid and activation of the 5-lipoxygenase pathway in human leukocytes.

Enhanced penetration by ethanol of exogenous arachidonic acid into human leukocyte preparations results in the production of large amounts of eicosanoids including 5-, 12- and 15-hydroxyeicosatetraenoic acids as well as the leukotrienes C4 delta 6-trans-leukotriene B4, 12-epi-delta 6-trans-leukotriene B4, leukotriene B4 and 5(S), 12(S)-dihydroxyeicosatetraenoic acid. The production of these compounds is affected by the concentrations of both ethanol and arachidonic acid independently in a complex manner with stimulation at lower concentrations and later relative inhibition. It was shown that the resulting leukotriene B4 exhibited the same specific activity as exogenous arachidonic acid when labelled substrate was used.

Arachidonate 5-Lipoxygenase↗
PubMed1986

Reactivity patterns of human anticardiolipin and other antiphospholipid antibodies in syphilitic sera.

Sera from patients with proven cases of syphilis were tested for the presence of antibodies to structurally important phospholipids by using qualitative and quantitative assays. All 47 sera examined qualitatively contained antibodies to cardiolipin, phosphatidic acid, and phosphatidylserine, but not antibodies to other selected phospholipids. Such reactivity was not found in normal (Red Cross) sera. Although the degree of antibody binding to phospholipids varied in individual sera, reactivity was almost always greater with cardiolipin than with phosphatidic acid or phosphatidylserine. Binding saturability was found in sera as the cardiolipin concentration was increased over a constant area of nitrocellulose paper. Anti-cardiolipin binding measured by the protein A method gave results similar to the results measured by using anti-immunoglobulin G, which supports the conclusion that binding was to the Fab portion of the immunoglobulin molecule. When measured as a function of serum concentration and plotted in double-reciprocal fashion, the anti-cardiolipin binding data for two syphilitic sera had similar Kd values but different Bmax values. Stoichiometric calculations indicated that approximately 11,000 to 16,000 mol of cardiolipin appeared to be bound per mole of labeled second antibody. These observations may mean that the anti-cardiolipin antibody does not recognize the individual cardiolipin molecule as the antigenic site but recognizes some structural form of the phospholipid or that steric hindrance related to the interaction of the phospholipid with nitrocellulose paper prevented the bulk of cardiolipin molecules from reaching. The structural specificity of the antibodies identified excludes the possibility that these antibodies are directed against the phosphodiester linkage. These findings should give impetus to future study of a potential pathogenic or marker role for these antibodies in syphilis and in other syndromes in which membrane damage may be a primary event.

Antibodies↗