Experimental human endotoxemia
All endotoxemia-related procedures were performed according to our standard continuous LPS-infusion protocol (12). In short, subjects were admitted to the research unit situated on the Medium Care department of the Radboud university medical center for approximately ten hours. Subjects had to refrain from consumption of alcohol and caffeine (24 h), and food and drinks (12 h) prior to LPS administration. Upon admission on the first LPS challenge day, two antebrachial venous cannulas were placed to allow administration of fluids, study medication and LPS. A radial artery catheter (BD Infusion Therapy Systems, Sandy, Utah, USA) was placed under ultrasound guidance to allow serial blood sampling and continuous hemodynamic monitoring. To reduce the risk of vasovagal responses (14), hydration fluids (2.5% glucose/0.45% sodium chloride) were administered as an initial prehydration bolus of 1.5L in the 45 min prior to LPS administration, and at a rate of 150 mL/hr for the remainder of the experiment. After prehydration, a bodyweight adjusted bolus dose of 1 ng/kg LPS (E. coli type O:113, lot no. 94332B1; List Biological Laboratories, Campbell, USA) was administered intravenously, directly followed by continuous infusion of LPS at a rate of 0.5 ng/kg/hr for three hours. Blood samples were serially obtained to construct time-concentration curves of circulating cytokines. Heart rate and intra-arterial blood pressure were measured using a 4-lead electrocardiogram (M50 Monitor, Philips, Eindhoven, the Netherlands) and a radial artery pressure transducer (Edwards Lifesciences, Irvine, California, USA). Hemodynamic parameters were recorded every 5 s using in-house developed software. Every 30 min, body temperature was measured using a tympanic thermometer (FirstTemp Genius 2, Covidien, Dublin, Ireland). Flu-like symptoms (headache, nausea, cold shivers, myalgia and back pain) were scored every 30 min using a numeric six-point Likert scale (0 = no symptoms, 5 = worst ever experienced). A composite score was then calculated as the sum of all previous elements, resulting in a total symptom score ranging from 0 to 25. Furthermore, general malaise was scored on an eleven-point scale (0 = no symptoms, 10 = worst ever experienced).
• Product #9433 – GMP LPS Lipopolysaccharide List™ Hpt™ From Escherichia Coli Type O113