Faculty Bibliography

Nitric oxide (NO) can participate in cellular signaling. In this study, monoclonal antibodies against proteins from the growth factor-mediated signalling pathway were used to identify a set of 126-, 56-, 43-, and 40-kDa proteins phosphorylated on tyrosine at NO stimulation of murine fibroblasts overexpressing the human epidermal growth factor receptor. The band corresponding to the 126-kDa protein was FAK. The 56-kDa protein was Src kinase, and the doublet 43- and 40-kDa protein corresponded to the extracellular-regulated MAP kinases (ERK1/ERK2). The effects of NO on focal adhesion complexes were also investigated. FAK was constitutively associated with the adapter protein Grb2 in HER14 cells. Treatment of the cells with the NO donor, sodium nitroprusside, or with EGF did not change this association. We also detected a basal constitutive association of Src kinase with FAK in HER14 cells. In NO-treated cells, this association was stimulated. The doublet 43/40-kDa protein was identical to the ERK1/ERK2 MAP kinases. NO stimulated an increase in ERK1/ERK2 phosphorylation as assessed by a shift in its eletrophoretic mobility and by increased phosphotyrosine immunoreactivity. Furthermore, NO-dependent activation of ERK1/ERK2 depended on the intracellular redox status. Inhibition of glutathione synthesis was necessary to promote activation of the kinases

BACKGROUND: Stroke occurs in 1% to 7% of heart surgery. Aortic arch atherosclerosis is a risk factor for intraoperative stroke, and endarterectomy has been proposed to prevent stroke during heart surgery in patients with arch atheromas. METHODS AND RESULTS: Intraoperative transesophageal echocardiography was performed in 3404 patients undergoing heart surgery between 1990 and 1996. Use of transesophageal echocardiography was unselected and based on equipment availability. Aortic arch atheromas (>/=5 mm, or mobile) were seen in 268 (8%) patients. They were evaluated for intraoperative stroke (confirmed by a neurologist and cerebral infarction on computed tomography or magnetic resonance imaging). Arch endarterectomy was performed in 43 patients as an adjunct to their cardiac procedure in an attempt to prevent intraoperative stroke. The intraoperative stroke rate in all 268 patients with atheromas was high (15.3%). On univariate analysis, age, previous stroke, and arch endarterectomy were significantly associated with intraoperative stroke. On multivariate analysis, age (odds ratio 3.9, P =.01) and arch endarterectomy (odds ratio 3.6, P =.001) were independently predictive of intraoperative stroke. Mortality rate in all 268 patients was high (14.9%). These patients with atheromas also had a long recovery room, intensive care unit, and total hospital length of stay (48 days). CONCLUSIONS: Patients with protruding aortic arch atheromas are at high risk for intraoperative stroke, significant and multiple morbidity, prolonged hospital stay, and death resulting from heart surgery. Aortic arch endarterectomy is strongly associated with intraoperative stroke; its use should be carefully considered in light of these results

The isoprostanes (IsoPs) are a unique series of prostaglandin-like compounds formed in vivo from the free radical-catalyzed peroxidation of arachidonic acid. This review summarizes our current knowledge regarding these compounds. Novel aspects of the biochemistry and bioactivity of IsoPs are detailed and methods by which these compounds are analyzed are discussed. A considerable portion of this review deals with the utility of measuring IsoPs as markers of oxidant injury in human diseases particularly in association with risk factors that predispose to atherosclerosis, a condition in which excessive oxidative stress has been causally implicated.

The development of a specific, reliable and noninvasive method for measuring oxidative stress in humans is essential for establishing the role of free radicals in human diseases. Currently, accurate techniques to assess oxidant injury in vivo are extremely limited although a number of approaches are being investigated. Of these, the measurement of specific products of nonenzymatic lipid peroxidation, the F2-isoprostanes (F2-IsoPs), appears to be a more accurate marker of oxidative stress in vivo in humans than other available methods. The purpose of this brief review is to acquaint the reader with the IsoPs from a biochemical perspective and to provide information regarding the utility of quantifying these compounds as indicators of oxidant stress

Since the generation of superoxide and hydrogen peroxide by NADPH oxidase and nitric oxide (NO) by NO synthase (NOS) in granulocytes is NADPH-dependent, we investigated the production of NO, superoxide and H2O2 in glucose 6-phosphate dehydrogenase (G6PD)-deficient human granulocytes. Our results showed that upon stimulation with either 5 microg/ml of lipopolysaccharide (LPS) or 10 microM of phorbol 12-myristate 13-acetate (PMA), the production of nitrite in normal granulocytes was elevated, 252 +/- 135% and 239 +/- 72%, respectively, compared to the resting stage. In contrast, G6PD-deficient granulocytes did not produce more nitrite upon stimulation with either LPS or PMA compared to the resting stage. Western blot analysis indicated a normal expression pattern of inducible NOS in G6PD-deficient granulocytes. In addition, the production of H2O2 and superoxide was also significantly impaired in G6PD-deficient granulocytes compared to control cells. These data demonstrate that G6PD deficiency causes an impairment in the production of NO, superoxide and H2O2

Cardiac compression is a potentially life-threatening complication of heart surgery. This syndrome often has atypical manifestations, challenging our ability to make a rapid diagnosis and to institute emergent, life-saving treatment. We recently evaluated one such patient who showed cardiac compression caused by an unusual paracardiac mass. The addition of transesophageal echocardiography to the usual transthoracic study may have played more than just a diagnostic role in this case

Strand breakage of supercoiled pBR322 DNA by a Fenton system is increased in the presence of palladium or platinum (Pt) ions. Neither Pd nor Pt ions can substitute for iron in the Fenton system. We have obtained several lines of evidence that Pd and Pt ions in the presence of a Fenton system can augment the production of OH., as monitored by a spectrophotometric method quantifying hydroxylated salicylate or by a fluorometric method quantifying catechol production. Furthermore, the promoting effect of both metal ions on OH. production was substantiated by the identification of multiple hydroxylated products of salicylate [2,3-dihydroxybenzoate (A), 2,5-dihydroxybenzoate (B), and catechol (C)] using HPLC. The concentrations of A, B, and C produced in the control were 4.5, 8.0, and 2.0 microM, respectively; whereas, their respective concentrations increased to 23.6, 42.0 and 10.0 microM with the addition of Pd ions. The observed phenomenon was further confirmed by the identification of HO-DMPO spin adducts using ESR spectroscopy. Taken together, our data suggest that the mechanism of Pd or Pt ion-mediated exacerbation of DNA damage by a Fenton system is due to the promotion of OH. production by these metal ions