👤 Kurt Leibundgut

OxPL-apoB (oxidized phospholipids [OxPL] on apoB-100), which include OxPL present on Lp(a) (lipoprotein[a]), are associated with higher cardiovascular risk. Experimental studies suggest that OxPL may influence platelet function. This observational study assessed the association of OxPL-apoB with intrinsic and on‑clopidogrel platelet reactivity and long-term cardiovascular events in patients undergoing coronary angiography with or without percutaneous coronary intervention in 2040 patients in the EXCELSIOR trial (Impact of Extent of Clopidogrel-Induced Platelet Inhibition During Elective Stent Implantation on Clinical Event Rate). The association of OxPL-apoB to expression of CD62P, CD41, or PAC-1 levels and intrinsic and on-clopidogrel platelet reactivity to collagen and ADP was determined. The relationship of OxPL-apoB and Lp(a) to myocardial infarction-free survival and all-cause mortality at a median of 7 years was assessed using Cox regression models. Elevated levels of OxPL-apoB were associated with the severity of coronary obstruction, and higher prevalence of prior myocardial infarction, percutaneous coronary intervention, and coronary artery bypass graft surgery. No significant associations were present between OxPL-apoB and intrinsic or on-clopidogrel platelet reactivity or activation of platelet receptors. Analyzed individually in separate multivariable models, both OxPL-apoB (hazard ratio, 1.022 [95% CI, 1.005-1.040]; In patients undergoing coronary angiography with or without percutaneous coronary intervention, OxPL-apoB was not associated with intrinsic and on-clopidogrel platelet reactivity mediated by collagen or ADP. The association of OxPL-apoB and Lp(a) suggests that the accumulation of OxPL on Lp(a) may be a key determinant of long-term cardiovascular outcomes. URL: https://www.clinicaltrials.gov; Unique identifier: NCT00457236. Show less

Fatal hyperammonemia secondary to chemotherapy for hematological malignancies or following bone marrow transplantation has been described in few patients so far. In these, the pathogenesis of hyperammonemia remained unclear and was suggested to be multifactorial. We observed severe hyperammonemia (maximum 475 μmol/L) in a 2-year-old male patient, who underwent high-dose chemotherapy with carboplatin, etoposide and melphalan, and autologous hematopoietic stem cell transplantation for a neuroblastoma stage IV. Despite intensive care treatment, hyperammonemia persisted and the patient died due to cerebral edema. The biochemical profile with elevations of ammonia and glutamine (maximum 1757 μmol/L) suggested urea cycle dysfunction. In liver homogenates, enzymatic activity and protein expression of the urea cycle enzyme carbamoyl phosphate synthetase 1 (CPS1) were virtually absent. However, no mutation was found in CPS1 cDNA from liver and CPS1 mRNA expression was only slightly decreased. We therefore hypothesized that the acute onset of hyperammonemia was due to an acquired, chemotherapy-induced (posttranscriptional) CPS1 deficiency. This was further supported by in vitro experiments in HepG2 cells treated with carboplatin and etoposide showing a dose-dependent decrease in CPS1 protein expression. Due to severe hyperlactatemia, we analysed oxidative phosphorylation complexes in liver tissue and found reduced activities of complexes I and V, which suggested a more general mitochondrial dysfunction. This study adds to the understanding of chemotherapy-induced hyperammonemia as drug-induced CPS1 deficiency is suggested. Moreover, we highlight the need for urgent diagnostic and therapeutic strategies addressing a possible secondary urea cycle failure in future patients with hyperammonemia during chemotherapy and stem cell transplantation. Show less