Objective To establish an in vivo imaging method of normal or tumorous liver in mice by using a new type nanoparticle contrast agent, ExiTron nano 12000, coupled with micro-CT imaging.Methods Six 6-8-week old male C57BL/6J mice were randomly divided into group A and group group B, by intravenous injection of 50μL and 100μL Ex-iTron nano 12000, respectively.In vivo Micro-CT scans were performed before contrast agent injection, 3 minutes, 24 hours, 7, 14, 28 and 56 days after injection.To determine which dose is suitable for long-term studies, gray scale value a-nalysis was performed on selected region of interest ( ROI) in the left lobe and right anterior lobe of the liver, and the chan-ges of liver tissue contrast was monitored after ExiTron nano 12000 injection.Three male HBV transgenic mice bearing liver tumors ( group C) were intravenously injected with the determined dose of ExiTron nano 12000 and were monitored by mi-cro-CT scans as above described.At 56 days after ExiTron nano 12000 injection, the mice were sacrificed and liver sam-ples were taken for histological analysis.Results Cross-sectional images taken at various time points and the average gray scale value ( AGSV) analysis in the mouse liver revealed that the AGSV peaked at 24 hours after injection of contrast rea-gent and good contrast still presented in the livers within 56 days of observation for both groups, though group B showed a significantly higher contrast than group A (P＜0.01).Those data indicated that the dose of group B (100μL) was better to maintain ExiTron nano 12000 in the liver of mice for a long time.Contrast-enhanced by 100μL of ExiTron nano 12000, the liver tumor nodules in the mice of group C could be clearly delineated by Micro CT imaging during a 56 days observa-tion.Histological analysis revealed atypical hyperplasia, enlarged nuclei with hyperchromasia and cell necrosis in the tumors.Conclusions An in vivo imaging method was established to non-invasively visualize mouse liver using micro-CT combined with nanoparticle-based contrast agent and this technology may be applied to a live imaging of murine primary liv-er tumors.

Objective To analyze the Alb-cre/DTR mouse phenotype, and establish a model of induced liver damage to serve basic researches of liver diseases.Methods The introduced Alb-cre and DTR mice were crossed to obtain Alb-cre/DTR mice and the genomic DNAs were extracted from the tail tissue of the mice for genotying by PCR.Diphtheria toxin was intraperitoneally(i.p.)injected into the Alb-cre/DTR mice, then the body weights were monitored and the sera were collected for the detection of serum ALT and AST levels.Results By crossing Alb-cre and DTR mice we obtained the Alb-cre and DTR double transgenic mouse.The intraperitoneal injection of diphtheria toxin in a dose of 0.625 ng/g body weight significantly induced liver injury in these mice, as showed by the elevated levels of ALT and AST, the gross appearance of liver damage and the pathological changes such as necrosis in the liver tissue.Conclusions We have ob-tained a novel mouse strain of Alb-cre/DTR by crossing Alb-cre and DTR mice.Liver damages in those Alb-cre/DTR mice can be induced by injection of diphtheria toxin.This established mouse model of inducible liver damage is a useful platform for the studies of liver damage and recovery, as well as liver transplantation.

Objective To investigate the role of interleukin-1 receptor type 1 (IL-1R1) signaling in H1N1 influenza virus infection. Methods IL-1R1 knockout ( IL-1R1-/-) mice and wild type ( WT) mice were infected intranasally with 2×104 TCID50(50% tissue culture infective dose) of influenza virus H1N1 PR8. Changes in clinical signs, survivals and bodyweights of those mice were monitored daily for 14 consecutive days. Three mice from each group were sacrificed at 3, 7 and 14 days post infection (d. p. i), from which whole lungs were harvested. A part of the lobes was fixed in 4% paraformaldehyde for histopatho-logical assessment and the rest were split and stored at-80 centigrade for further analysis. Real-time quanti-tative PCR and cytometric bead array ( CBA) were performed to detect viral loads in lungs and inflammatory cytokines in supernatants of lung homogenates. Results The mice in both groups showed severe symptoms after the infection of PR8. The maximum bodyweight loss of IL-1R1-/- mice [(24. 22±0. 80) % at 8 d. p. i] was lower than that of WT mice [(28. 03±1. 51)% at 9 d. p. i] (P<0. 05). The IL-1R1-/- mice with PR8 infection showed a higher survival rate (90%) as compared with that of the control group (40%) (P<0. 05). No statistical differences in virus loads were observed between the two groups at 3, 7 and 14 d. p. i. The lung weight to body weight ratio of IL-1R1-/-mice [(1. 42±0. 03) %] was lower than that of WT mice [(1. 79±0. 08) %] at 3 d. p. i (P<0. 05). Pathological changes in IL-1R1-/- mice were less severe than those in WT mice. CBA detection assay revealed that the proinflammatory cytokines in lungs of IL-1R1-/-mice were less than those in WT mice. Conclusion IL-1R1 signaling plays a pathogenic role in mice infec-ted with 2×104 TCID50 of influenza virus PR8 by promoting inflammatory responses.