L.J. Roberts

Elevated CSF prostaglandin E2 levels in patients with probable AD

OBJECTIVE To determine CSF eicosanoid concentrations and brain cyclo-oxygenase activity in AD patients and age-matched control subjects. BACKGROUND Nonsteroidal anti-inflammatory drugs may benefit AD patients by inhibiting cyclo-oxygenases and thereby reducing prostaglandin (PG) production or oxidant stress in the CNS. METHODS CSF eicosanoid and F2-isoprostane (IsoP) levels were determined in seven probable AD patients and seven age-matched control subjects. Cyclo-oxygenase activity was determined in microsomes prepared from the hippocampus of 10 definite AD patients and 8 age-matched control subjects. All measurements were made using gas chromatography/mass spectrometry. RESULTS CSF concentrations of prostaglandin (PG) E2 were increased fivefold (p < 0.01) and 6-keto-PGF1alpha was decreased fourfold (p < 0.01) in probable AD patients. There was no change in total CSF eicosanoid concentration in probable AD patients. CSF F2-IsoP, a quantitative marker of lipid peroxidation in vivo, was increased in probable AD patients (p < 0.05). Cyclo-oxygenase activity in the hippocampus from definite AD patients was not different from age-matched control subjects. CONCLUSIONS These data suggest that cyclo-oxygenase activity may not contribute significantly to CNS oxidative damage in AD. Increased CSF PGE2 concentration in probable AD patients suggest that cyclo-oxygenase inhibitors may benefit AD patients by limiting PG production.

Formation of Reactive Cyclopentenone Compounds in Vivo as Products of the Isoprostane Pathway

Cyclopentenone prostaglandins A2 and J2 are reactive compounds that possess unique biological activities. However, the extent to which they are formed in vivo remains unclear. In this study, we explored whether D2/E2-isoprostanes undergo dehydration in vivo to form A2/J2-isoprostanes. Oxidation of arachidonic acid in vitro generated a series of compounds that were confirmed to be A2/J2-isoprostanes by mass spectrometric analyses. A2/J2-isoprostanes were detected in vivo esterified to lipids in livers from normal rats at a level of 5.1 ± 2.3 ng/g, and levels increased dramatically by a mean of 24-fold following administration of CCl4. An A2-isoprostane, 15-A2t-isoprostane, was obtained and found to readily undergo Michael addition with glutathione and to adduct covalently to protein. A2/J2-isoprostanes could not be detected in the circulation, even following CCl4administration, which we hypothesized might be explained by rapid formation of adducts. This was supported by finding that essentially all the radioactivity excreted into the urine following infusion of radiolabeled 15-A2t-isoprostane into a human volunteer was in the form of a polar conjugate(s). These data identify a new class of reactive compounds that are produced in vivo as products of the isoprostane pathway that can exert biological effects relevant to the pathobiology of oxidant injury.

Resolution of Musculoskeletal Symptoms in the Carcinoid Syndrome after Treatment with the Somatostatin Analog Octreotide

Excerpt Carcinoid tumors are neoplasms of the enterochromaffin cells, the primary clinical manifestations of which include flushing, diarrhea, cardiac valvular lesions, and carcinoid crises with br...

Isolevuglandins as a gauge of lipid peroxidation in human tumors

Abstract The cellular production of free radicals or reactive oxygen species (ROS) can lead to protein, lipid or DNA modifications and tumor formation. The cellular lipids undergo structural changes through the actions of enzymes (e.g. cyclooxygenases) or free radicals to form a class of compounds called Isolevuglandins (IsoLGs). The recruitment and continued exposure of tissue to ROS and IsoLGs causes increased cell proliferation, mutagenesis, loss of normal cell function and angiogenesis. The elevated concentration of ROS in cancerous tissues suggests that these mediators play an important role in cancer development. We hypothesized that tumors with elevated ROS levels would similarly possess an increased concentration of IsoLGs when compared with normal tissue. Using D11, an ScFv recombinant antibody specific for IsoLGs, we utilized immunohistochemistry to visualize the presence of IsoLG in human tumors compared to normal adjacent tissue (NAT) to the same tumor. We found that IsoLG concentrations were elevated in human breast, colon, kidney, liver, lung, pancreatic and tongue tumor cells when compared to NAT and believe that IsoLGs can be used as a gauge indicative of lipid peroxidation in tumors. HighlightsThe concentration of reactive oxygen species (ROS) in tumor cells can be elevated.ROS can be responsible for lipid peroxidation and isolevuglandin (IsoLG) formation.D11, an antibody specific for IsoLG, was used to detect IsoLG in human tumors.IsoLG concentration was elevated in human tumors in comparison to normal tissue.IsoLG can serve as a biomarker of lipid peroxidation in human tumors.