Quantification of F-ring and D-/E-ring isoprostanes and neuroprostanes in Alzheimer's disease.
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Aged↗
Biomedical subjects
L J Roberts
Publications and source records attributed to L J Roberts.
Brain regional quantification of F-ring and D-/E-ring isoprostanes and neuroprostanes in Alzheimer's disease.
Isoprostanes (IsoP) are produced exclusively from free radical damage to arachidonic acid, a fatty acid that is evenly distributed throughout white matter and gray matter, whereas neuroprostanes (NPs) are generated analogously from docosahexaenoic acid (DHA), a fatty acid enriched in gray matter where it is concentrated in neurons. IsoP and NPs derive from endoperoxide intermediates that isomerize to D/E-ring forms or that are reduced to F-ring compounds. We quantified F-ring and D/E-ring IsoP and NPs in temporal and parietal cortex, hippocampus, and cerebellum of nine definite Alzheimer's disease (AD) patients and 11 age-matched controls. Total NP levels (F-ring plus D/E-ring), but not total IsoP, were significantly greater in AD than controls (P: < 0.0001); only cerebral regions in AD patients had NPs greater than controls (P: < 0.05). The F-ring to D/E-ring ratio for NPs, but not IsoP, was 40 to 70% lower in all brain regions of AD patients compared to controls (P: < 0.005). These data extend results from in situ techniques, that have localized reactive products of lipid peroxidation primarily to neurons, by quantifying significantly greater free radical damage to the DHA-containing compartments in cerebrum in AD patients than controls, and suggest that one mechanism of increased oxidative stress may be diminished reducing capacity in DHA-containing compartments.
Alleles↗
Assessment of oxidant stress in allergic asthma by measurement of the major urinary metabolite of F2-isoprostane, 15-F2t-IsoP (8-iso-PGF2alpha).
Asthma is a chronic inflammatory disease of the airways which may involve an oxidant injury to the lung. Assessment of oxidant stress is difficult in vivo, but measurement of F2-isoprostanes (F2-IsoPs), free radical-catalysed products of arachidonic acid, appears to offer a reliable approach for quantitative measurement of oxidative stress status in vivo. We have recently developed a mass spectrometric assay for 2,3-dinor-5,6-dihydro-15-F2t-IsoP (15-F2t-IsoP-M), the major urinary metabolite of the F2-IsoP, 15-F2t-IsoP (8-iso-PGF2a). Measurement of the urinary excretion of this metabolite offers a reliable index of oxidative stress status in vivo that has advantages over measuring unmetabolized F2-IsoPs in urine and plasma. To assess the occurrence of oxidative stress in patients with atopic asthma following allergen exposure in vivo by measuring the urinary excretion of 15-F2t-IsoP-M. Analysis of 15-F2t-IsoP-M by GC-NICI-MS in nine mild atopic asthmatics following inhaled allergen provocation and four asthmatic subjects after inhaled challenge with methacholine. Urinary excretion of 15-F2t-IsoP-M increased at 2 h after allergen challenge and remained significantly elevated in all urine collections during the subsequent 8-h period of the study compared to the baseline value (ANOVA, and Student-Newman-Keuls multiple comparisons test). No increase in the urinary excretion of 15-F2t-IsoP-M occurred after inhalation of methacholine. Allergen challenge causes an oxidant injury in human atopic asthmatics. 15-F2t-IsoP-M is a valuable marker of oxidant stress in vivo.
Allergens↗
Enhanced hippocampal F2-isoprostane formation following kainate-induced seizures.
We attempted to obtain evidence for the occurrence of oxidant injury following seizure activity by measuring hippocampal F2-isoprostanes (F2-IsoPs), a reliable marker of free radical-induced lipid peroxidation. Formation of F2-IsoPs esterified in hippocampal phospholipids was correlated with hippocampal neuronal loss and mitochondrial aconitase inactivation, a marker of superoxide production in the kainate model. F2-IsoPs were measured in microdissected hippocampal CA1, CA3 and dentate gyrus (DG) regions at various times following kainate administration. Kainate produced a large increase in F2-IsoP levels in the highly vulnerable CA3 region 16 h post injection. The CA1 region showed small, but statistically insignificant increases in F2-IsoP levels. Interestingly, the DG, a region resistant to kainate-induced neuronal death also showed marked (2.5-5-fold) increases in F2-IsoP levels 8, 16, and 24 h post injection. The increases in F2-Isop levels in CA3 and DG were accompanied by inactivation of mitochondrial aconitase in these regions. This marked subregion-specific increase in F2-Isop following kainate administration suggests that oxidative lipid damage results from seizure activity and may play an important role in seizure-induced death of vulnerable neurons.
Aconitate Hydratase↗
Increase in plasma esterified F2-isoprostanes following intravenous iron infusion in patients on hemodialysis.
BACKGROUND: In epoetin-treated dialysis patients, currently iron is administered by the intravenous route to maintain optimum erythropoiesis. However, rapid infusion of iron in excess of transferrin binding capacity can lead to the availability of unbound iron that can theoretically catalyze peroxidation of lipids, such as low-density lipoprotein (LDL), which when oxidatively modified is proinflammatory and promotes atherogenesis. METHODS: To address this issue, our study used one of the most specific measures of lipid peroxidation available, namely gas chromatography/mass spectometry (GC/MS) analysis of F2-isoprostanes. Using a prospective design, blood samples were collected 15 minutes before (pre) and 30 minutes after (post) a one-hour infusion of 700 mg bolus of intravenous iron in 22 adult home-hemodialysis patients on a non-hemodialysis day. RESULTS: With iron-dextran infusion, serum iron markedly increased (mean +/- SE, 42 +/- 4 vs. 311 +/- 92 microg/dL, P < 0.0001) and exceeded the transferrin saturation of 100% in 22 out of 22 patients (pre 23 +/- 3 vs. post 165 +/- 8%, P < 0.0001). Plasma concentrations of free F2-isoprostanes did not change significantly following infusion of iron (pre 40 +/- 5 vs. post 39 +/- 6 pg/mL). However, levels of F2-isoprostanes esterified in plasma lipoproteins increased significantly in the postinfusion samples (pre 199 +/- 19 vs. post 233 +/- 25 pg/mL, P < 0.004). Pre-infusion levels of serum iron correlated directly with pre-infusion levels of esterified F2-isoprostanes (r = 0.56, P = 0.008), which persisted in the postinfusion period (r = 0.43, P = 0.04). However, there was no correlation between esterified F2-isoprostanes and serum ferritin levels. In the last four patients in whom blood samples were collected five hours after the intravenous iron infusion, there were further increases in esterified F2-isoprostanes that very closely correlated with postinfusion serum iron levels (r = 0.99, P = 0.013). In a control study, the in vitro addition of iron dextran to blood samples did not increase free or esterified F2-isoprostanes, suggesting that the increase in esterified F2-isoprostanes seen in vivo after iron infusion in patients is not due to a procedural artifact. CONCLUSION: Collectively our data suggest that high levels of serum iron appearing soon after a large bolus of iron infusion is associated with significant, albeit modest, increases in levels of F2-isoprostanes esterified in plasma lipoproteins that tended to increase with time. Although it is uncertain whether this degree of lipid peroxidation may have deleterious effects, it may be sagacious to explore whether this can be prevented by slow infusion of frequent smaller doses of iron and, if necessary, along with administration of antioxidants.
Adult↗
Outcome of intrathecal opioids in chronic non-cancer pain.
Eighty-eight patients (58 women and 30 men; mean age 53.4 years) with chronic non-cancer pain present on average for 9.8 years were evaluated following treatment with intrathecal opioids for an average duration of 36.2 months. Outcome measures were global pain relief, physical activity levels, medication consumption, work status, intrathecal opioid side-effects, proportion of patients who ceased therapy and patient satisfaction. The most common diagnosis in this group was lumbar spinal or radicular pain after failed spinal surgery (n= 55, 63%). At the time of follow-up, mean pain relief was 60% with 74% of patients (36 of 49) reporting increased activity levels. Oral medication intake was significantly reduced (Medication Quantification Scale Score prior to implantation 31.0+/-2.6 and at follow-up 12.7+/-1.4; n= 48; p< 0.0001). These gains were not accompanied by a change in work status (43 of 50 working age patients not working at follow-up). There were frequent reports of opioid side-effects, including sexual dysfunction and menstrual disturbance. Technical complications occurred with the drug administration device, most often catheter related, requiring at least one further surgical procedure in 32 patients (40%). Patient satisfaction with intrathecal opioids was high, with 45 of 51 (88%) reporting satisfaction. Mean intrathecal morphine dose increased from 9.95+/-1.49 mg/day (mean+/-SEM) at 6 months to 15.26+/-2.52 mg/day 36 months after initiation of therapy. Drug administration systems were permanently removed in five patients (6%). Intrathecal opioid therapy appears to have a place in the management of chronic non-cancer pain. Therapy does not seem to be significantly inhibited by the development of tolerance.
Activities of Daily Living↗
Supplementation with vitamin E but not with vitamin C lowers lipid peroxidation in vivo in mildly hypercholesterolemic men.
Although the use of vitamin E supplements has been associated with a reduction in coronary events, assumed to be due to lowered lipid peroxidation, there are no previous long-term clinical trials into the effects of vitamin C or E supplementation on lipid peroxidation in vivo. Here, we have studied the long-term effects of vitamins C and E on plasma F2-isoprostanes, a widely used marker of lipid peroxidation in vivo. As a study cohort, a subset of the "Antioxidant Supplementation in Atherosclerosis Prevention" (ASAP) study was used. ASAP is a double-masked placebo-controlled randomized clinical trial to study the long-term effect of vitamin C (500 mg of slow release ascorbate daily), vitamin E (200 mg of D-alpha-tocopheryl acetate daily), both vitamins (CellaVie), or placebo on lipid peroxidation, atherosclerotic progression, blood pressure and myocardial infarction (n = 520 at baseline). Lipid peroxidation measurements were carried out in 100 consecutive men at entry and repeated at 12 months. The plasma F2-isoprostane concentration was lowered by 17.3% (95% CI 3.9-30.8%) in the vitamin E group (p = 0.006 for the change, as compared with the placebo group). On the contrary, vitamin C had no significant effect on plasma F2-isoprostanes as compared with the placebo group. There was also no interaction in the effect between these vitamins. In conclusion, long-term oral supplementation of clinically healthy, but hypercholesterolemic men, who have normal vitamin C and E levels with a reasonable dose of vitamin E lowers lipid peroxidation in vivo, but a relatively high dose of vitamin C does not. This observation may provide a mechanism for the observed ability of vitamin E supplements to prevent atherosclerosis.
Aged↗
2,3-Dinor-5,6-dihydro-15-F(2t)-isoprostane: a bioactive prostanoid metabolite.
15-F(2t)-isoprostane (15-F(2t)-IsoP), also termed 8-isoprostaglandin F(2alpha), is one of a series of prostanoids formed by free radical-mediated peroxidation of arachidonic acid and exerts potent biological actions such as vasoconstriction. We recently demonstrated that 15-F(2t)-IsoP is metabolized in humans to a major metabolite, 2,3-dinor-5,6-dihydro-15-F(2t)-IsoP (15-F(2t)-IsoP-M). 15-F(2t)-IsoP-M can also potentially be formed as a product of free radical-induced oxidation of the low abundance fatty acid gamma-linolenic acid. We confirmed that 15-F(2t)-IsoP-M is generated during oxidation of gamma-linolenic acid and explored whether it may exhibit biological activity. 15-F(2t)-IsoP-M caused marked constriction of porcine surface retinal and intraparenchymal brain microvessels, comparable to that observed with 15-F(2t)-IsoP. These effects were associated with increased thromboxane A(2) (TXA(2)) formation and were virtually abolished by TXA(2)-synthase and -receptor inhibitors (CGS-12970 and L-670596). Vasoconstriction induced by either 15-F(2t)-IsoP or 15-F(2t)-IsoP-M on perfused ocular choroid was also abrogated by TXA(2)-synthase inhibition as well as by removal of endothelium. Similar to 15-F(2t)-IsoP, 15-F(2t)-IsoP-M evoked vasoconstriction and TXA(2) generation by activating Ca(2+) influx from nonvoltage-gated channels (SK&F96365 sensitive) in the retina and from both nonvoltage- and N-type voltage-gated Ca(2+) channels (omega-conotoxin MVIIA sensitive), respectively, in brain endothelial and astroglial cells; smooth muscle cells were unresponsive to both agents. Cross-desensitization experiments further suggest that 15-F(2t)-IsoP and 15-F(2t)-IsoP-M act on the same receptor mechanism. Findings reveal a novel concept by which a beta-oxidation metabolite of 15-F(2t)-IsoP that can also be formed by nonenzymatic oxidation of gamma-linolenic acid is equivalently bioactive to 15-F(2t)-IsoP and may prolong the vascular actions of F(2)-IsoPs.
15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
Retro-orbital tumour--an uncommon cause of headache in pregnancy.
Retro-orbital tumour was the cause of headache and neuropathic facial pain in a 31-year-old pregnant woman. The diagnosis had been overlooked as a result of a long history of migraine. There was exacerbation of the pain throughout the pregnancy, particularly in the third trimester. Pharmacological agents commonly used to manage neuropathic pain states were relatively contraindicated due to potential adverse effects on the fetus. Cognisant of such limitations imposed by pregnancy, we used multimodal therapy in an attempt to control the pain. This included morphine, paracetamol, amitriptyline, ketamine and psychological support. The management challenges are described.
Adult↗
Identification of platelet-activating factor as the inflammatory lipid mediator in CCl4-metabolizing rat liver.
Unmitigated oxidative stress is deleterious, as epitomized by CCl4 intoxication. In this well-characterized model of free radical-initiated damage, liver metabolism of CCl4 to CCl3. causes lipid peroxidation, F-ring isoprostane formation, and pathologic leukocyte activation. The nature of the mediator that couples oxidation to the hepatotoxic inflammatory response is uncharacterized. We found that oxidatively modified phosphatidylcholines were present in the livers of CCl4-exposed rats and not in livers from control animals, that CCl4 metabolism generated lipids that activated 293 cells stably transfected with the human platelet-activating factor (PAF) receptor, and that this PAF-like activity was formed as rapidly as isoprostane-containing phosphatidylcholine (iPC) during oxidation. iPC and the PAF-like activity also had similar chromatographic properties. The potential for iPC activation of the PAF receptor has been unexplored, but we conclude that iPC themselves did not activate the PAF receptor, as phospholipase A1 hydrolysis completely destroyed iPC, but none of the PAF-like bioactivity. Oxidatively fragmented phospholipids are potent agonists of the PAF receptor, but mass spectrometry characterized PAF as the major inflammatory component coeluting with iPC. Oxidatively fragmented phospholipids and iPC are markers of free radical generation in CCl4-intoxicated liver, but PAF generation by activated hepatic cells generated the inflammatory agent.
Animals↗
Science, medicine, and the future: Leishmaniasis.
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Animals↗
Formation of novel D-ring and E-ring isoprostane-like compounds (D4/E4-neuroprostanes) in vivo from docosahexaenoic acid.
Free radical-mediated oxidant injury and lipid peroxidation have been implicated in a number of neural disorders. We have reported that bioactive prostaglandin D2/E2-like compounds, termed D2/E2-isoprostanes, are produced in vivo by the free radical-catalyzed peroxidation of arachidonic acid. Docosahexaenoic acid, in contrast to arachidonic acid, is the most abundant unsaturated fatty acid in brain. We therefore questioned whether D/E-isoprostane-like compounds (D4/E4-neuroprostanes) are formed from the oxidation of docosahexaenoic acid. Levels of putative D4/E4-neuroprostanes increased 380-fold after oxidation of docosahexaenoic acid in vitro from 15.2 +/- 6.3 to 5773 +/- 1024 ng/mg of docosahexaenoic acid. Subsequently, chemical approaches and liquid chromatography electrospray ionization tandem mass spectrometry definitively identified these compounds as D4/E4-neuroprostanes. We then explored the formation of D4/E4-neuroprostanes from a biological source, rat brain synaptosomes. Basal levels of D4/E4-neuroprostanes were 3.8 +/- 0.6 ng/mg of protein and increased 54-fold after oxidation (n = 4). We also detected these compounds in fresh brain tissue from rats at levels of 12.1 +/- 2.4 ng/g of brain tissue (n = 3) and in human brain tissue at levels of 9.2 +/- 4.1 ng/g of brain tissue (n = 4). Thus, these studies have identified novel D/E-ring isoprostane-like compounds that are derived from docosahexaenoic acid and that are formed in brain in vivo. The fact that they are readily detectable suggests that ongoing oxidative stress is present in the central nervous system of humans and animals. Further, identification of these compounds provides a rationale for examining their role in neurological disorders associated with oxidant stress.
Animals↗
Measurement of F(2)-isoprostanes as an index of oxidative stress in vivo.
In 1990 we discovered the formation of prostaglandin F(2)-like compounds, F(2)-isoprostanes (F(2)-IsoPs), in vivo by nonenzymatic free radical-induced peroxidation of arachidonic acid. F(2)-IsoPs are initially formed esterified to phospholipids and then released in free form. There are several favorable attributes that make measurement of F(2)-IsoPs attractive as a reliable indicator of oxidative stress in vivo: (i) F(2)-IsoPs are specific products of lipid peroxidation; (ii) they are stable compounds; (iii) levels are present in detectable quantities in all normal biological fluids and tissues, allowing the definition of a normal range; (iv) their formation increases dramatically in vivo in a number of animal models of oxidant injury; (v) their formation is modulated by antioxidant status; and (vi) their levels are not effected by lipid content of the diet. Measurement of F(2)-IsoPs in plasma can be utilized to assess total endogenous production of F(2)-IsoPs whereas measurement of levels esterified in phospholipids can be used to determine the extent of lipid peroxidation in target sites of interest. Recently, we developed an assay for a urinary metabolite of F(2)-IsoPs, which should provide a valuable noninvasive integrated approach to assess total endogenous production of F(2)-IsoPs in large clinical studies.
Animals↗
Expression of cyclooxygenase-2 and prostaglandins by B-1 cells and B-CLL cells.
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Animals↗
Individual drinking changes following a brief intervention among college students: clinical significance in an indicated preventive context.
This study investigated the clinical significance of previously reported statistically significant mean reductions in drinking and related problems among college students in a randomized trial of a brief indicated preventive intervention (G. A. Marlatt et al., 1998). Data were analyzed over a 2-year follow-up for participants from a high-risk intervention group (n = 153), a high-risk control group (n = 160), and a functional comparison group (n = 77). A risk cutpoint for each dependent measure was based on the functional comparison group distribution. Compared with the high-risk controls, more individuals in the high-risk intervention group improved and fewer worsened, especially on alcohol-related problems and, to a lesser extent, on drinking pattern variables. These data from a prevention context clarify the magnitude and direction of individual change obscured by group means.
Adult↗
A new standard for the assessment of disease progression in murine cutaneous leishmaniasis.
Infection of mice with Leishmania major has been used both as a model for the cutaneous disease in humans and as a model for the more general control and function of helper T cells in immunity. In both cases, disease patterns and disease progression have been assessed by two complementary methods, lesion size and parasite burden in the draining lymph nodes. We propose a much improved method for the graphical representation of lesion development which conveys more information with better accuracy. We also describe a polymerase chain reaction method for determining parasite burden, which is faster and allows the analysis of larger numbers of experimental animals than the current limiting dilution analysis. Moreover, these methods are equally applicable to other infectious diseases, an obvious one being schistosomiasis.
Animals↗
Placental isoprostane is significantly increased in preeclampsia.
We determined placental tissue levels, production rates, and secretion rates of isoprostanes for placentas obtained from women with normal pregnancies and women with preeclampsia, a hypertensive disorder of pregnancy. Isoprostanes are markers of oxidative stress that exert biological actions such as vasoconstriction. Placental tissue was rinsed and immediately frozen in liquid nitrogen to determine tissue levels of total and free isoprostane. Placental tissue pieces were also incubated in serum-free DMEM for 48 h at 37 degrees C in 95% air/5% CO(2) to determine production rates. Isolated placental cotyledons were perfused for the determination of secretion rates. All samples were analyzed by EIA for isoprostane using an antibody specific for 8-Iso-PGF(2) (15-F(2t)-IsoP). In addition, medium samples were analyzed for malondialdehyde (MDA), a breakdown product of lipid peroxidation. We found that tissue levels of free isoprostane and total isoprostane (free plus esterified forms) were significantly higher for preeclamptic placentas than for normal placentas. Concentrations of isoprostane and MDA in the medium increased progressively during 48 h of incubation of placental explants. At 48 h of incubation, the mean concentrations of both isoprostane and MDA were significantly higher for the placentas from preeclamptic women than for the placentas from normal pregnant women. Concentrations of MDA were highly correlated with those of isoprostane. Induction of oxidative stress with xanthine plus xanthine oxidase increased placental production of isoprostane by normal tissue to a level similar to that of preeclamptic tissue. Placental secretion of isoprostane was eightfold greater toward the maternal side of the placenta than toward the fetal side, and was increased sixfold on the maternal side and twofold on the fetal side by inducing oxidative stress with t-butyl hydroperoxide. This study presents new information that isoprostanes are formed and secreted by the human placenta and provides convincing evidence that oxidative stress and lipid peroxidation are abnormally increased in placentas of preeclamptic women.
Adult↗
Hypogonadism in patients treated with intrathecal morphine.
OBJECTIVE: The objective of this study was to investigate the hypothalamic-pituitary-gonadal response to intrathecal opioids. PATIENTS: Thirty patients receiving intrathecal morphine for chronic nonmalignant pain were studied for clinical and biochemical evidence of hypogonadism. Ten men and 10 postmenopausal women with chronic pain of similar duration but who were not receiving any form of opioid therapy acted as control subjects. RESULTS: Men and both premenopausal and postmenopausal women had evidence of hypogonadism with low levels of serum testosterone or estrogen coupled with low levels of pituitary gonadotrophins. Control subjects had hormone levels in the expected range for their sex and age. Two men demonstrated recovery after ceasing intrathecal opioid therapy. CONCLUSIONS: Hypogonadotrophic hypogonadism is a common complication of intrathecal opioid therapy in both men and women.
Adult↗