Selective early cardiolipin peroxidation after traumatic brain injury: an oxidative lipidomics analysis

OBJECTIVE: Enhanced lipid peroxidation is well established in traumatic brain injury. However, its molecular targets, identity of peroxidized phospholipid species, and their signaling role have not been deciphered. METHODS: Using controlled cortical impact as a model of traumatic brain injury, we employed a newly developed oxidative lipidomics approach to qualitatively and quantitatively characterize the lipid peroxidation response. RESULTS: Electrospray ionization and matrix-assisted laser desorption/ionization mass spectrometry analysis of rat cortical mitochondrial/synaptosomal fractions demonstrated the presence of highly oxidizable molecular species containing C(22:6) fatty acid residues in all major classes of phospholipids. However, the pattern of phospholipid oxidation at 3 hours after injury displayed a nonrandom character independent of abundance of oxidizable species and included only one mitochondria-specific phospholipid, cardiolipin (CL). This selective CL peroxidation was followed at 24 hours by peroxidation of other phospholipids, most prominently phosphatidylserine, but also phosphatidylcholine and phosphatidylethanolamine. CL oxidation preceded appearance of biomarkers of apoptosis (caspase-3 activation, terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling-positivity) and oxidative stress (loss of glutathione and ascorbate). INTERPRETATION: The temporal sequence combined with the recently demonstrated role of CL hydroperoxides (CL-OOH) in in vitro models of apoptosis suggest that CL-OOH may be both a key in vivo trigger of apoptotic cell death and a therapeutic target in experimental traumatic brain injury.     

Mechanism-based chemopreventive strategies against etoposide-induced acute myeloid leukemia: free radical/antioxidant approach.

Etoposide (VP-16) is extensively used to treat cancer, yet its efficacy is calamitously associated with an increased risk of secondary acute myelogenous leukemia. The mechanisms for the extremely high susceptibility of myeloid stem cells to the leukemogenic effects of etoposide have not been elucidated. We propose a mechanism to account for the etoposide-induced secondary acute myelogenous leukemia and nutritional strategies to prevent this complication of etoposide therapy. We hypothesize that etoposide phenoxyl radicals (etoposide-O(.)) formed from etoposide by myeloperoxidase are responsible for its genotoxic effects in bone marrow progenitor cells, which contain constitutively high myeloperoxidase activity. Here, we used purified human myeloperoxidase, as well as human leukemia HL60 cells with high myeloperoxidase activity and provide evidence of the following. 1) Etoposide undergoes one-electron oxidation to etoposide-O(.) catalyzed by both purified myeloperoxidase and myeloperoxidase activity in HL60 cells; formation of etoposide-O(.)radicals is completely blocked by myeloperoxidase inhibitors, cyanide and azide. 2) Intracellular reductants, GSH and protein sulfhydryls (but not phospholipids), are involved in myeloperoxidase-catalyzed etoposide redox-cycling that oxidizes endogenous thiols; pretreatment of HL60 cells with a maleimide thiol reagent, ThioGlo1, prevents redox-cycling of etoposide-O(.) radicals and permits their direct electron paramagnetic resonance detection in cell homogenates. VP-16 redox-cycling by purified myeloperoxidase (in the presence of GSH) or by myeloperoxidase activity in HL60 cells is accompanied by generation of thiyl radicals, GS(.), determined by HPLC assay of 5, 5-dimethyl-1-pyrroline glytathionyl N-oxide glytathionyl nitrone adducts. 3) Ascorbate directly reduces etoposide-O(.), thus competitively inhibiting etoposide-O(.)-induced thiol oxidation. Ascorbate also diminishes etoposide-induced topo II-DNA complex formation in myeloperoxidase-rich HL60 cells (but not in HL60 cells with myeloperoxidase activity depleted by pretreatment with succinyl acetone). 4) A vitamin E homolog, 2,2,5,7, 8-pentamethyl-6-hydroxychromane, a hindered phenolic compound whose phenoxyl radicals do not oxidize endogenous thiols, effectively competes with etoposide as a substrate for myeloperoxidase, thus preventing etoposide-O(.)-induced redox-cycling. We conclude that nutritional antioxidant strategies can be targeted at minimizing etoposide conversion to etoposide-O(.), thus minimizing the genotoxic effects of the radicals in bone marrow myelogenous progenitor cells, i.e., chemoprevention of etoposide-induced acute myelogenous leukemia.     

Chronic hepatitis C in Latinos: natural history, treatment eligibility, acceptance, and outcomes

OBJECTIVES: The natural history of chronic hepatitis C and treatment response are different between blacks and Caucasians, but little comparable data is available about Latinos. METHODS: A cross-sectional secondary analysis to investigate differences between 421 anti-HCV-positive, treatment-na?ve, HCV-viremic Latinos and 2,510 Caucasians in 24 VA medical centers enrolled in a prospective study. RESULTS: Latinos were infected at a younger age and were less likely to have blood contact during combat, surgery, and needle stick injury, but were more frequently HIV coinfected (20.4%vs 3.9%, p < 0.0001) and prior HAV infection (39.9%vs 26.4%, p= 0.0001). Latinos were more likely to be treatment candidates, but less likely to actually initiate treatment. Liver histology (123 Latinos, 743 Caucasians) showed no difference in fibrosis or fibrosis rate, but steatosis (54.7%vs 43.2%, p= 0.038) was more common in Latinos. Eighty-eight Latinos and 481 Caucasians were subsequently treated with interferon-ribavirin: body mass index (BMI), duration of infection, baseline tests, liver histology and genotype distribution were similar. Compared with Caucasians, Latinos discontinued treatment prematurely more often (39.8%vs 28.9%, p= 0.043) and tended to have lower sustained virological response (SVR) rates (14.8%vs 22.5%, p= 0.10). Multivariate analysis found Latino race and history of recent alcohol use to be associated with early treatment discontinuation, whereas genotype and viral load but not ethnicity to be associated with SVR. CONCLUSIONS: Latinos were infected younger, more frequently HIV coinfected, more likely to meet criteria for antiviral therapy yet less likely to initiate treatment and had a trend toward lower SVR rates than Caucasians, but not in severity of liver disease. Latino ethnicity was associated with early discontinuation but not as an independent predictor of SVR.     

Transferring AAC intervention to the home

Purpose: To evaluate the acquisition of AAC skills during an initial clinical trial and assess subsequent transfer of the training to the home setting. Method: A 12-year-old male with autism was first seen in a clinical setting to establish the use of a voice-output communication device. After learning to use the device to request access to preferred objects in the clinical trial, the intervention was transferred to the home. Follow-up with the parent was conducted via e-mail and telephone. Videotapes were made of initial home-based sessions to enable evaluation of the participant's progress. Results: The programme was successful in teaching the participant to use a portable AAC device to make requests during the clinical trial and then in two home-based activities. Conclusion: An initial clinical trial with follow-up support for parents may be an efficient method for beginning AAC intervention and transferring the training procedures to the home setting.     

Immune hemolytic anemia associated with tolmetin and suprofen

This article reports the first case of immune hemolytic anemia possibly associated with the ingestion of suprofen. The patient suffered from massive hemoglobinuria and acute renal failure. Serologic studies of the patient's serum revealed suprofen-dependent red cell antibodies. However, tolmetin-dependent antibodies were also found in the serum, showing the same properties as the suprofen antibodies and an even higher titer. The patient not only had drug-dependent antibodies in the serum, but also had developed autoantibodies, a phenomenon that has been described for several other drugs. The working mechanism by which suprofen and tolmetin caused immune hemolysis had properties of both the immune complex model and the induction of autoimmunity. Although it was unclear whether the immune hemolytic anemia was the result of suprofen, tolmetin, or cross-reacting antibodies, we feel that suprofen should be added to the list of nonsteroidal anti-inflammatory drugs associated with a positive direct antiglobulin test.