Or the care and use of research animals under the GermanOr the care and use

Or the care and use of research animals under the German
Or the care and use of research animals under the German Animal Protection Law. Animal experiments were approved by the local government (Regierungspr idium T ingen).In vivo PET imaging studiesinformation about the importance of air or 100 oxygen breathing on [18F]FAZA uptake during the preincubation time and the first hour after [18F]FAZA administration, we designed a third protocol in which mice breathed 100 oxygen 2 minutes prior and 1 h after [18F]FAZA administration (P2). Moreover, we analyzed the role of air breathing in between the PET scans (P1 vs. P2). Breathing protocols were as follows (Figure 1A): ?P0: room air during the entire procedure (n = 10; 21 oxygen); ?P1: 100 oxygen 1 h prior to tracer injection and during the entire scan time (n = 7); ?P2: 100 oxygen 2 min prior to tracer injection, 1 h p.i. and during the scans, which were performed at 2 h and 3 h p.i. The mice breathed room air between the scans (n = 7). Mice were kept in a chamber under 100 oxygen at a flow rate of 0.6 L/min without anesthesia during the pre-injection time (P1, P2) and during the uptake phase after the injection. During the scans, the animals were placed in a custom-made chamber on the scanner bed (Figure 1B). Mice were kept conscious except during tracer injection (1 min) and PET scans (10 min). Again, [18F]FDG scans were preemptively performed to confirm the viability of the tumor tissue. We divided the CT26 colon carcinoma-bearing mice into two groups as CT26 colon carcinomas reach an exponential growth phase at day 12 to 14 after CT26 cell inoculation which, in turn, would cause a higher heterogeneity of the tumors, as the larger CT26 tumors showed a tendency toward higher [18F]FAZA uptake (Table 1). The first group (n = 4) was scanned under the P0 protocol and on the subsequent day under the P1 protocol; the second group (n = 3) was scanned under the P0 and P2 protocols. In addition, we scanned mice individually using the breathing protocols P0 (n = 6), P1 (n = 3) and P2 (n = 4) to obtain at least seven mice per breathing protocol group (P0, P1 and P2) for analysis.PET data analysisPET studies investigating the tumor type-dependent uptake of [ 18 F]FAZA were conducted with PyV-mT C57/BL6 mice (n = 9 mice, n = 20 tumors) and CT26 tumor-bearing BALB/c mice (n = 10 mice, n = 10 tumors). Under isoflurane anesthesia, the tail veins of the mice were injected with 14.2 ?0.5 MBq [18F]FDG or 12.3 ?1.0 MBq [18F]FAZA on two consecutive days. [18F]FDG scans were performed to UNC0642 supplier identify large necrotic tumor regions in mice with large PyV-mT mammary carcinomas (> 1.5 cm3) that were subsequently ignored during [18F]FAZA PET image analysis. In addition we performed [ 18 F]FDG PET scans in some CT26 colon carcinoma bearing mice and could not detect large necrotic areas. For [ 18 F]FDG, a 1 h uptake time was allowed prior to a 10 min static scan. Mice were kept under 1.5 isoflurane anesthesia with an air flow rate of 0.6 L/min using a dedicated vaporizer (Vetland, Louisville, KY, USA) for the entire uptake and scan time. The body temperature of mice was maintained at 37 on the scanner bed and in the incubation chambers by using heating pads. During the [18F]FAZA uptake time, mice were kept conscious in room air. The main study was performed using static PET scan protocols described in the next section (breathing protocols). However, prior to onset of our study we performed antecedent PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/26104484 dynamic studies to ensure that the static PET scans are performed dur.