Moorflpi

Ten minutes after the first prick was performed images were captured with a Dino-Lite Pro digital dermascope polarizer with a resolution of 1.3 megapixel (Dino-Lite, Naarden, Holland) to identify incidents of bleeding not readily visible by regular visual inspection. The speckle contrast flowmetry (MoorFLPI, Moor Instruments, Devon, UK) were performed to measure the mean superficial perfusion. The distance between the speckle contrast flowmetry and the application area was 45 cm, the total exposure time was 8.3 ms and the gain setting was 150 units. The images from the speckle contrast flowmetry were analysed on appertaining software (MoorFLPI Review V 4.0, Moor instruments) to assess the flare intensity within the predefined squares. Using an averaged region of interest approach the mean superficial perfusion for each square was found. Additionally, the diameters of the wheals were measured on the longitudinal diameter and on the orthogonal midpoint diameter with a transparent ruler with mm resolution. One investigator measured the wheal diameters in the same order that the SPTs had been applied and the lack of wheals, e.g. in response to saline was noted.

Experiments were performed in a rat embolic model established previously [12 (link),16 (link)]. Briefly, 9-week-old Sprague Dawley (SD) rats (363 ± 5 g, n = 25; BioLASCO, Taipei, Taiwan) were anesthetized with Inactin (100 mg/kg), followed by tracheostomy and cannulation of the carotid artery for blood pressure measurement. The right iliac artery was cannulated with a catheter for injection of the clot, which was lodged in the left iliac artery. The MNP or MNP-rtPA was injected and guided with an NdFeB magnet (4.9 kG) in a reciprocating motion from aortic bifurcation to the hind limb for one hour. Aortic/iliac flow measurement and tissue perfusion were measured with ultrasonic flowmetry (T206, Transonic Systems; Ithaca, NY, USA) and a laser Doppler perfusion imager (MoorFLPI; Moor Instruments, Devon, UK), respectively. Half reperfusion time was defined as the time required to restore iliac blood flow to 50% of the basal level after drug administration. At the end of the experiment, blood samples were collected by cardiac puncture for hematology analysis by a cell analyzer (HEMAVET^® 950LV; Drew Scientific, Cumbria, UK).

Microcirculation of the injured skin was measured via a high resolution laser speckle imaging device (LSI; Moor FLPI, Moor Instruments Inc., Wilmington, DE, USA), positioned 10–20 cm from each wound. Image acquisition settings were: Gain: 200, Exposure time: 4 ms, Time constant: 1.0 s, Filter: 250 frames, Sample interval: 20 s, Image resolution: 760 × 568. To achieve image analysis, all frames obtained were merged together into one image. Three regions of interest were drawn including one area of wound flux and two areas of background flux (normal skin perfusion) on opposite sides of the wound. Calculations comprised the fold change of Median Wound Flux/Median Background flux for each wound.

Blood flow was assessed by laser speckle contrast imaging (LSCI; MoorFLPI, Moor Instruments Ltd., Axminster, UK) placed parallel to the surface of the tissue at a distance of 25 cm.¹⁵ By LSCI, blood flow was obtained in real time without tissue contact.¹⁵ Regions of interest (ROIs) were marked on the liver (segment 3), the stomach (antrum: 3 cm from the pylorus, and corpus: 3 cm from the greater curvature), the small intestine (10 cm from the cecum), and the upper lip. Also, blood flow was assessed on the snout by laser Doppler flowmetry (LDF)¹⁶ chosen because, here, the prone position of the pig prohibited perpendicular positioning of the LSCI camera. Blood flow in the selected ROIs was determined post hoc by a programmed algorithm¹⁵ (Python versus 2.7.6, Python Software Foundation, Wilmington, USA). All measurements (LSCI/LDF) during the study were obtained at the same ROIs and represent recordings over 30 seconds.