Browsing by Author "Wozniak, Marcin"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    An observational cohort feasibility study to identify microvesicle and miRNA biomarkers of acute kidney injury following paediatric cardiac surgery
    (Wolters Kluwer, 2018-09) Sullo, Nikol; Mariani, Silvia; JnTala, Maria; Kumar, Tracy; Wozniak, Marcin; Pais, Paolo; Westrope, Claire; Lotto, Attilio; Murphy, Gavin; Smallwood, Dawn T.
    Objectives: Micro-RNA, small noncoding RNA fragments involved in gene regulation, and microvesicles, membrane-bound particles less than 1 μm known to regulate cellular processes including responses to injury, may serve as disease-specific biomarkers of acute kidney injury. We evaluated the feasibility of measuring these signals as well as other known acute kidney injury biomarkers in a mixed pediatric cardiac surgery population. Design: Single center prospective cohort feasibility study. Setting: PICU. Patients: Twenty-four children (≤ 17 yr) undergoing cardiac surgery with cardiopulmonary bypass without preexisting inflammatory state, acute kidney injury, or extracorporeal life support. Interventions: None. Measurements and Main Results: Acute kidney injury was defined according to modified Kidney Diseases Improving Global Outcomes criteria. Blood and urine samples were collected preoperatively and at 6–12 and 24 hours. Microvesicles derivation was assessed using flow cytometry and NanoSight analysis. Micro-RNAs were isolated from plasma and analyzed by microarray and quantitative real-time polymerase chain reaction. Data completeness for the primary outcomes was 100%. Patients with acute kidney injury (n = 14/24) were younger, underwent longer cardiopulmonary bypass, and required greater inotrope support. Acute kidney injury subjects had different fractional content of platelets and endothelial-derived microvesicles before surgery. Platelets and endothelial microvesicles levels were higher in acute kidney injury patients. A number of micro-RNA species were differentially expressed in acute kidney injury patients. Pathway analysis of candidate target genes in the kidney suggested that the most often affected pathways were phosphatase and tensin homolog and signal transducer and activator of transcription 3 signaling. Conclusions: Microvesicles and micro-RNAs expression patterns in pediatric cardiac surgery patients can be measured in children and potentially serve as tools for stratification of patients at risk of acute kidney injury.
  • Thumbnail Image
    ItemEmbargo
    A Phase I study to determine the pharmacokinetic profile, safety and tolerability of sildenafil (Revatio® ) in cardiac surgery: the REVAKI-1 study.
    (Wiley, 2016-12-01) Ring, Arne; Morris, Tom; Wozniak, Marcin; Sullo, N.; Dott, W.; Verheyden, Veerle; Kumar, Tracey; Brunskill, Nigel; Vaja, Rakesh; Murphy, G. J.
    AIMS: Acute kidney injury (AKI) is a common and severe complication of cardiac surgery. There is no effective prevention or treatment. Sildenafil citrate (Revatio® , Pfizer Inc.), a phosphodiesterase type 5 inhibitor, prevents post cardiac surgery AKI in pre-clinical studies, however its use is contraindicated in patients with symptomatic cardiovascular disease. The aim of this study is to assess the safety and pharmacokinetics of intravenous sildenafil in cardiac surgery patients. METHODS: We conducted an open label, dose escalation study with six patients per dose level. The six doses were 2.5 mg, 5 mg or 10 mg as a bolus, either alone or followed by an additional 2 h infusion of 2.5 mg sildenafil. RESULTS: Thirty-six patients entered the trial, of which 33 completed it. The mean age was 69.9 years. One patient died during surgery, two others were removed from the trial before dosing (all at dose level 5 mg + 2.5 mg). The pharmacokinetic profile of sildenafil was similar to previously published studies. For a dose of 10 mg administered as a bolus followed by 2.5 mg administered over 2 h the results were AUC∞ 537 ng h ml-1 , Cmax 189.4 ng ml-1 and t1/2 10.5 h. The drug was well tolerated with no serious adverse events related to drug administration. Higher sildenafil doses stabilized post-surgery nitric oxide bioavailability. CONCLUSIONS: Pharmacokinetics of sildenafil during cardiopulmonary bypass were comparable to those of other patient groups. The drug was well tolerated at therapeutic plasma levels. These results support the further evaluation of sildenafil for the prevention of AKI in cardiac surgery.