Substrate and regulatory functions of eicosapentaenoic and docosahexaenoic acids for the 5-lipoxygenase pathway. Implications for pulmonary responses.
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Animals↗
Biomedical subjects
R A Lewis
Publications and source records attributed to R A Lewis.
Intracellular retention of the 5-lipoxygenase pathway product, leukotriene B4, by human neutrophils activated with unopsonized zymosan.
The cellular and extracellular distribution of leukotriene B4 (LTB4) generated in human neutrophilic polymorphonuclear leukocytes (PMN) stimulated with unopsonized zymosan has been compared with that generated in PMN activated by the calcium ionophore. The amounts of extracellular and intracellular LTB4 were quantitated by radioimmunoassay. The authenticity of the immunoreactive LTB4 was confirmed by the elution of a single immunoreactive peak after reverse phase-high performance liquid chromatography (RP-HPLC) at the retention time of synthetic LTB4, by the identical elution time of a peak of radiolabeled product derived from [3H]arachidonic acid-labeled PMN with the immunoreactive product, and by the comparable chemotactic activity on a weight basis of immunoreactive LTB4 and synthetic LTB4 standard. Under optimal conditions of stimulation by unopsonized zymosan, more than 78% of the generated immunoreactive LTB4 remained intracellular, whereas with optimal activation by the ionophore, less than 8.6% of immunoreactive LTB4 was retained. Resolution by RP-HPLC of the products from the supernatants and cell extracts of [3H]arachidonic acid-labeled PMN stimulated with unopsonized zymosan and those stimulated with calcium ionophore allowed identification and measurement of 5-hydroxyeicosatetraenoic acid (5-HETE), 6-trans-LTB4, LTB4, and omega oxidation products of LTB4 by radioactivity. With zymosan stimulation of PMN, 5-HETE and the 6-trans-LTB4 diastereoisomers were not released, LTB4 was partially released, and the omega oxidation products of LTB4 were preferentially extracellular in distribution. In contrast, with ionophore stimulation, only 5-HETE had any duration of intracellular residence being equally distributed intra- and extracellularly throughout the 30-min period of observation; 6-trans-LTB4, LTB4, and the omega oxidation products of LTB4 were retained at less than 19%. The respective distributions of 5-HETE after zymosan and ionophore stimulation were not altered by the introduction of albumin to the reaction mixtures to prevent reacylation, or by hydrolysis of the cell extract to uncover any product that had been reacylated. The finding that stimulation of PMN with unopsonized zymosan results in the cellular retention of 5-lipoxygenase products suggests that release of these metabolites may be an event that is regulated separately from their generation.
Arachidonate Lipoxygenases↗
Choroideremia is linked to the restriction fragment length polymorphism DXYS1 at XQ13-21.
Choroideremia (McK30310), an X-linked hereditary retinal dystrophy, causes night-blindness, progressive peripheral visual field loss, and, ultimately, central blindness in affected males. The location of choroideremia on the X chromosome is unknown. We have used restriction fragment length polymorphisms from the X chromosome to determine the regional localization of choroideremia by linkage analysis in families with this disease. One such polymorphic locus, DXYS1, located on the long arm (Xq) within bands q13-q21, shows no recombination with choroideremia at lod = 5.78. Therefore, with 90% probability, choroideremia maps within 9 centiMorgans (cM) of DXYS1. Another polymorphic locus, DXS11, located within Xq24-q26, also shows no recombination with choroideremia, although at a smaller lod score of 1.54 (90% probability limit theta less than 30 cM). This linkage with DXS11, a marker that is distal to DXYS1, suggests that the locus for choroideremia is also distal to DXYS1 and lies between these two markers in the region Xq13-q24. These results provide regional mapping for the disease that may be useful for prenatal diagnosis and, perhaps ultimately, for isolating the gene locus for choroideremia.
Choroid↗
Modulation of the generation and release of leukotrienes from leukocytes.
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Arachidonate Lipoxygenases↗
Subclass-specific receptors for sulfidopeptide leukotrienes.
Separate receptors for LTC4 and LTD4 have been identified and characterized by physiologic and radioligand binding criteria. LTD4 receptors appear to be plasma-membrane-associated and to display characteristics previously described for many hormone receptors, such as inhibition of agonist binding by guanine nucleotides and Na+, suggesting a postreceptor linkage to adenylate cyclase of an inhibitory nature. LTC4 receptors have a substantial subcellular distribution; agonist binding to the receptor is not influenced by monovalent ions or guanine nucleotides but is enhanced by divalent cations. Within these two major subclass receptors with specificity for LTC4 and LTD4, respectively, there is an additional heterogeneity in terms of affinities. It is considered likely that a third receptor mediates the distinct actions of LTE4 on a guinea pig tracheal spirals, where this agonist exhibits greater contractile potency than LTD4 and LTC4 and elicits hyperreactivity to histamine that is not a nonspecific response to a prior contraction.
Animals↗
Regulation of mediator release from mouse bone marrow-derived mast cells by glucocorticoids.
Mouse bone marrow-derived mast cells (BMMC), which were differentiated from their bone marrow precursors during 14 days of culture in the presence of a T cell lymphokine, were cultured in the absence or in the presence of 0.01 to 5 microM dexamethasone (DEX) for periods of 6 to 96 hr to assess the effects of steroid treatment on stimulus-dependent mediator release. Preincubation of the BMMC for 24 hr with DEX inhibited the subsequent immunoglobulin (Ig) E-dependent release of beta-hexosaminidase in a dose-dependent manner by up to 38% (mean, n = 7) at 1 microM DEX, and the decrease was statistically significant at DEX concentrations greater than or equal to 0.5 microM. DEX (1 microM) inhibited granule secretion from BMMC in a time-dependent manner; the decrease was statistically significant after a preincubation period of 6 hr, was maximal after preincubation times greater than or equal to 24 hr, and was reversible by 24 hr of incubation in medium lacking the steroid. Preincubation for 24 hr with DEX also inhibited the IgE-dependent biosynthesis and release of the immunoreactive leukotrienes (LT)C4 and LTB4 in a dose-dependent manner by up to 56% (n = 7) and 54% (n = 7), respectively, at 1 microM DEX, and the decrease was statistically significant for each product at DEX concentrations greater than or equal to 0.1 microM. In contrast, BMMC preincubated with DEX for 24 hr before sensitization and antigen challenge demonstrated a statistically significant increase in the release of immunoreactive prostaglandin (PG) D2 at DEX concentrations greater than or equal to 0.1 microM and a maximal enhancement of 188% (n = 3) at 1 microM DEX. The effect of 1 microM DEX on the enhancement of IgE-dependent PGD2 generation was significant after 6 hr, and was maximal by 72 hr. The inhibitory effects of DEX on the antigen-induced release of 5-lipoxygenase pathway products were confirmed by the physical measurements of 5-hydroxy-eicosatetraenoic acid (5-HETE) and LTC4, and by isotopic measurement of [3H]LTC4 after reverse-phase high performance liquid chromatography (RP-HPLC). As assessed by fluorescence cytofluorography of IgE-sensitized BMMC that were interacted with F(ab')2 rabbit anti-mouse epsilon and fluorescein isothiocyanate-labeled F(ab')2 goat anti-rabbit IgG-F(ab')2, the number of IgE-Fc receptors on the cell surface decreased by more than 55% after treatment for 24 hr with 1 microM DEX.+
Animals↗
Immunisation of 4-6 month old Gambian infants with Edmonston-Zagreb measles vaccine.
Five different vaccination schedules were used to immunise Gambian infants aged 4-6 months against measles with the attenuated Edmonston-Zagreb strain of virus, which has a history of passage in human diploid cells. Vaccine aerosol given either by mask in a dose of 3500 or 7000 plaque-forming units (PFU) or from a plastic bag at a dose of 7000 PFU raised haemagglutinin-inhibiting or plaque-inhibiting measles antibody 16-24 weeks after vaccination to a titre of 1 in 8 or greater in all but 3 of the 51 children so vaccinated. All 21 infants given 11 400 PFU of vaccine intradermally in two divided doses and the 21 given 39 000 PFU of the virus subcutaneously also had satisfactory levels of measles antibody 16 weeks after vaccination. None of the vaccinated children had clinical evidence of measles in the 12 to 17 months after vaccination. The Edmonston-Zagreb vaccine, given subcutaneously or by other routes at 4-6 months, may be useful in preventing measles in infants in African cities, where 15-30% of children have measles before they are 9 months old, which is the recommended age for immunisation with the chick-cell-adapted strains of measles virus.
Aerosols↗
Characterization and biologic properties of 5,12-dihydroxy derivatives of eicosapentaenoic acid, including leukotriene B5 and the double lipoxygenase product.
Leukotriene B5 (LTB5) and three stereoisomers were prepared biosynthetically from eicosapentaenoic acid and compared with the analogous derivatives of arachidonic acid for their chemotactic and aggregating effects on human neutrophilic polymorphonuclear leukocytes. Leukotriene B4 (LTB4), LTB5, and the 6-trans-diastereoisomers of each were generated by activating polymorphonuclear leukocytes with the calcium ionophore A23187 in the presence of 14C-labeled and unlabeled arachidonic acid or 14C-labeled and unlabeled eicosapentaenoic acid, respectively. The double lipoxygenase products, (5S,12S)-6-trans-8-cis-LTB4 and (5S,12S)-6-trans-8-cis-LTB5, were generated from 5S-hydroxyeicosatetraenoic acid and racemic 5-hydroxyeicosapentaenoic acid intermediates by incubation with platelet sonicates. The products of each reaction were isolated by reverse-phase-high performance liquid chromatography and identified by their retention times relative to the appropriate totally synthetic standards, ultraviolet absorption spectra, immunoreactivity in a radioimmunoassay for LTB4, and, for all but the double lipoxygenase products, by incorporation of radiolabel from the specific polyunsaturated fatty acid source. When the concentration of LTB5 eliciting maximum chemotactic response of human polymorphonuclear leukocytes, 50 ng/ml (1.5 X 10(-7) M), and that eliciting a maximum aggregation response, 20 ng/ml (5.9 X 10(-8) M), were compared with the interpolated values of LTB4 eliciting comparable effects, the potency of LTB5 relative to LTB4 was approximately 1:8 as a chemotactic agent and about 1:20 as an aggregating agent. The double lipoxygenase products and the resolved 6-trans-diastereoisomers of the pentaene and tetraene series were about 2 logs less active as chemotactic factors than LTB4 and only (5S,12S)-6-trans-8-cis-LTB4 had even minimal aggregating activity.
Arachidonic Acid↗
Trabeculectomy v thermosclerostomy. A five-year follow-up.
Thirty-seven eyes with open-angle glaucoma were treated by trabeculectomy and 34 eyes were treated by thermosclerostomy. Thermosclerostomy lowered intraocular pressure to a slightly greater extent than trabeculectomy; however, the average difference was not statistically significant except for the second year. After five years, IOPs were less than 22 mm Hg without additional medications or surgery in 24 (65%) of eyes undergoing trabeculectomy and in 14 (41%) of eyes undergoing thermosclerostomy. When eyes were included that were treated with medication or additional glaucoma or cataract surgery, over 90% of eyes in each group had an IOP less than 22 mm Hg. Visual acuity declined frequently in both groups, and progression of cataract was the most common cause. Loss of visual acuity occurred much more frequently in patients who were older than 60 years than in younger patients.
Adult↗
Neovascular glaucoma after photoradiation therapy for uveal melanoma.
We describe two patients (two eyes) with neovascular glaucoma following photoradiation therapy (PRT) for ciliary body and iris melanoma. Histopathologic examination in one eye eight months after treatment disclosed widespread tumor necrosis. The second patient with iris melanoma showed total clinical disappearance of the lesion and regression of iris neovascularization six months later. The cause of the neovascular glaucoma is uncertain. The marked tumor necrosis induced by PRT might have resulted in release of a vasoproliferative factor that, in turn, led to the development of rubeosis and neovascular glaucoma.
Aged↗
Ethoxzolamide analogue gel. A topical carbonic anhydrase inhibitor.
An analogue of ethoxzolamide, 6-hydroxyethoxzolamide, was synthesized to enhance corneal permeability yet retain carbonic anhydrase inhibitory activity for use in lowering intraocular pressure. In a 1% suspension, the analogue caused a small but statistically significant unilateral reduction of IOP when applied to one eye of normal rabbits. When formulated in a gel vehicle, 6-hydroxyethoxzolamide caused a more prolonged and larger reduction in IOP in normal and ocular hypertensive rabbits compared with its effect in suspension or with the parent compound.
Animals↗
A syndrome of microcephaly and retinal pigmentary abnormalities without mental retardation in a family with coincidental autosomal dominant hyperreflexia.
We describe two brothers with severe microcephaly, unusual retinal pigmentary anomalies, intellectual function in the average or low average range, and a strong family history of hyperreflexia. The brothers have a previously undescribed syndrome, while the hyperreflexia appears to represent a coincidental autosomal dominant Mendelian trait, perhaps linked to the Kell blood group system.
Abnormalities, Multiple↗
Phosphorylation of deoxyguanosine in rat liver mitochondria.
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Animals↗
Enhancement of deoxyguanosine kinase activity in human lung fibroblast cells infected with human cytomegalovirus.
Studies were conducted to establish the relationship between deoxyguanosine kinase activity and human cytomegalovirus (HCMV) infection. Using both PAGE and isoelectric focusing techniques, extracts from untreated and infected cells were examined for deoxyguanosine kinase activity. The analyses resulted in identical migration rates for deoxyguanosine kinase activity in both infected and uninfected extracts. These data and kinetic studies based on apparent Km values suggest that HCMV enhanced a cellular kinase activity rather than coded for a virus specific enzyme. Furthermore, our results indicated that infected cells, like normal fibroblasts, contain two deoxyguanosine kinase activities, one of mitochondrial and another of cytosolic origin. Of particular interest was the observation that HCMV infection caused an enhancement of the mitochondrial enzymatic activity while the cytosolic activity showed no change. Deoxycytidine kinase activity which is associated with cytosolic deoxyguanosine kinase was unaffected by HCMV infection.
Cells, Cultured↗
Molecular determinants for functional responses to the sulfidopeptide leukotrienes: metabolism and receptor subclasses.
The end-organ effects of generated leukotriene C4 (LTC4) are regulated by a number of events subsequent to LTC4 biosynthesis. Ongoing peptide cleavage of LTC4 to the other sulfidopeptide leukotrienes, D4 and E4, would be regulatory, since LTC4 and LTD4 possess unique separate tissue receptors, as demonstrated on nonvascular smooth muscle. Further, both neutrophils and eosinophils possess a mechanism, dependent upon triggering of the respiratory burst, that modifies the structures and functional activities of the sulfidopeptide leukotrienes. This rapid inactivation process extends the previous appreciation that the sulfidopeptide leukotrienes function as local mediators of inflammation, rather than as hormones.
Animals↗
The Gardner syndrome. Significance of ocular features.
Gardner syndrome is a dominantly inherited familial cancer syndrome characterized by intestinal polyposis, bony hamartomata, and various soft tissue tumors. The risk of malignancy during adult life is essentially 100%, but as yet no phenotypic marker nor biochemical or serological linkage have been useful to identify the presence of the gene in early life. We studied three families in which multiple and bilateral patches of congenital hypertrophy of the retinal pigment epithelium are related uniquely to other phenotypic features of the Gardner gene. This readily identifiable characteristic may be useful to identify early in life individuals at risk for malignancy. We also suggest that the Gardner syndrome may be genetically heterogeneous.
Adult↗
von Recklinghausen neurofibromatosis. II. Incidence of optic gliomata.
The association of optic glioma with von Recklinghausen neurofibromatosis (NF) is well established. However, the incidence of these tumors in a large population of NF patients, prospectively evaluated with modern radiologic techniques, has not been established. We investigated the ophthalmic and intracranial features of NF in 217 patients aged 4 weeks to 69 years, in whom the diagnosis was based on stringent criteria. Tumors at various locations along the anterior visual pathway occurred in 15% of patients and were occasionally bilateral. The mean age of patients with chiasmal tumors was approximately 15 years less than patients with tumors of the optic nerve only. Two-thirds (67%) of all tumors were neither suspected historically nor detected by ophthalmologic examination. Neither the ophthalmoscopic absence of optic atrophy nor the normal results of roentgenograms of the optic foramina were reliable predictors of tumors detected by CT scan. The presence of optic glioma is not correlated to other ocular, skeletal, neurologic, or anamnestic risk factors.
Adolescent↗