Laser-induced fluorescence (LIF) measurements of OH(X 2Π) production following electron impact on water have been carried out over an energy range from threshold to 300 eV. Data have been made absolute using existing measurements of OH(X) production via dissociative attachment. The cross section reaches a maximum value of 2.1×10−16 cm2 at an energy of 75 eV. Dipole-allowed processes are shown to dominate the production of OH(X) particularly via the A(1B1) repulsive state, though significant population of higher rotational levels is demonstrated, indicating the relevance of other channels as in photodissociation.
Aims Lipoprotein(a) (Lp(a)) levels are generally constant throughout an individual’s lifetime and current guidelines recommend that a single measurement is sufficient to assess the risk of coronary artery disease (CAD). However, it is unclear whether a single measurement of Lp(a) in individuals with acute myocardial infarction (MI) is indicative of the Lp(a) level six months following the event. Methods and Results Lp(a) levels were obtained from individuals with NSTEMI or STEMI (n = 99) within 24 hours of hospital admission and after six months, who were enrolled in two randomized trials of evolocumab and placebo, and in individuals with NSTEMI or STEMI (n = 9) who enrolled in a small observation arm of the two protocols and did not receive study drug, but whose levels were obtained at the same time points. Median Lp(a) levels increased from 53.5 nmol/L [19,165] during hospital admission to 58.0 nmol/L [14.8, 176.8] six months after the acute infarction (p = 0.02). Subgroup analysis demonstrated no difference in the baseline, six-month, or change between the baseline and six-month Lp(a) values between the STEMI and NSTEMI groups and between the group which received evolocumab and the group that did not. Conclusion This study demonstrated that Lp(a) levels in individuals with acute MI are significantly higher six months after the initial event. Therefore, a single measurement of Lp(a) in the peri-infarction setting is not sufficient to predict the Lp(a)-associated CAD risk in the post-infarction period. Trial registration number Evolocumab in Acute Coronary Syndrome Trial [EVACS I] NCT03515304, Evolocumab in Patients with Acute Myocardial Infarction [EVACS II], NCT04082442
Aims Platelet activation and endothelial dysfunction contribute to adverse outcomes in patients with acute coronary syndromes (ACS). The goals of this study were to assess the impact of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition on markers of platelet activation and endothelial dysfunction in ACS patients and the interaction among PCSK9, platelets, and endothelial cells (ECs) on left internal mammary artery (LIMA) vascular endothelium using specimens obtained during coronary artery bypass surgery (CABG). Methods and Results ACS patients enrolled in the Evolocumab in Acute Coronary Syndrome trials were randomized to placebo or a single dose of 420 mg evolocumab within 24 hours of hospitalization. Serum samples for analysis of platelet factor 4 (PF4) and P-selectin, markers of platelet activation, and von Willebrand factor (vWF), a marker of endothelial dysfunction, were obtained at baseline and 30 days. Additionally, LIMA segments obtained during CABG from patients who were and were not receiving evolocumab were immunostained with PCSK9; CD61, a platelet-specific marker; and CD31, an endothelial cell-specific marker. Forty-six participants were randomized to placebo or to evolocumab. Controlling for baseline levels, PF4 and vWF were significantly lower in the evolocumab, than in the placebo, group at 30 days. Immunostaining of LIMA specimens from twelve participants undergoing CABG revealed colocalization of PCSK9, CD61, and CD31 at the vascular endothelium. Administration of evolocumab was associated with decreased overlap of PCSK9, CD61, and CD31. Conclusions PCSK9 inhibition decreases markers of platelet activation and endothelial dysfunction in ACS patients. PCSK9 is associated with platelets and vascular ECs in LIMA segments and PCSK9 inhibition decreases that interaction.
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