Sterility testing of germ-free mouse colonies.

In biomedical research, germ-free and gnotobiotic mouse models enable the mechanistic investigation of microbiota-host interactions and their role on (patho)physiology. Throughout any gnotobiotic experiment, standardized and periodic microbiological testing of defined gnotobiotic housing conditions is a key requirement. Here, we review basic principles of germ-free isolator technology, the suitability of various sterilization methods, and the use of sterility testing methods to monitor germ-free mouse colonies. We also discuss their effectiveness and limitations, and share the experience with protocols used in our facility. In addition, possible sources of isolator contamination are discussed and an overview of reported contaminants is provided.

Intravital Imaging of Thrombosis Models in Mice.

Intravital microscopy is a powerful tool to study thrombosis in real time. The kinetics of thrombus formation and progression in vivo is studied after inflicting damage to the endothelium through mechanical, chemical, or laser injury. Mouse models of atherosclerosis are also used to induce thrombus formation. Vessels of different sizes and from different vascular beds such as carotid artery or vena cava, mesenteric or cremaster arterioles, can be targeted. Using fluorescent dyes, antibodies, or reporter mouse strains allows to visualize key cells and factors mediating the thrombotic processes. Here, we review the latest literature on using intravital microscopy to study thrombosis as well as thromboinflammation following transient middle cerebral artery occlusion, infection-induced immunothrombosis, and liver ischemia reperfusion.

Microbiota-derived tryptophan metabolites in vascular inflammation and cardiovascular disease.

The essential amino acid tryptophan (Trp) is metabolized by gut commensals, yielding in compounds that affect innate immune cell functions directly, but also acting on the aryl hydrocarbon receptor (AHR), thus regulating the maintenance of group 3 innate lymphoid cells (ILCs), promoting T helper 17 (TH17) cell differentiation, and interleukin-22 production. In addition, microbiota-derived Trp metabolites have direct effects on the vascular endothelium, thus influencing the development of vascular inflammatory phenotypes. Indoxyl sulfate was demonstrated to promote vascular inflammation, whereas indole-3-propionic acid and indole-3-aldehyde had protective roles. Furthermore, there is increasing evidence for a contributory role of microbiota-derived indole-derivatives in blood pressure regulation and hypertension. Interestingly, there are indications for a role of the kynurenine pathway in atherosclerotic lesion development. Here, we provide an overview on the emerging role of gut commensals in the modulation of Trp metabolism and its influence in cardiovascular disease development.

An evaluation of the serological and epidemiological effects of the outer envelope vaccine to leptospira.

BACKGROUND: The Shanghai Institute of Biological Products manufactured successfully a new outer envelope vaccine for leptospira in 1978. It has been confirmed by using animal tests and a number of human body trials that this vaccine is safe and effective, However, results regarding serological and epidemiological effects of the vaccine in population has not been reported. The objective of this study was to evaluate serological and epidemiological effects of this vaccine. METHODS: From May 1998 to May 1999, an evaluation of the serological and epidemiological effects of the outer envelope vaccine for leptospira made by Shanghai Institute of Biological Products was conducted among agricultural population aged 5 to approximately 60 years in an epidemic area of leptospirosis, in Jingzhou District, Jingzhou City, Hubei Province, China by microscopic agglutination test (MAT), cohort study, matched case-control study and screening method. RESULTS: The serological surveillance results of 77 students immunized showed that the successful rates of vaccination with the outer envelope vaccine of L. icterohaemorrhagiae sero-group and L. hebdomadis sero-group leptospira were 79.22% and 77.92%, respectively, the antibody geometric mean titer (GMT) of the two groups were 1:106.71 and 1:63.31, respectively, with 6.7-fold and 4.7-fold rises comparing with the group of those of the antibody before inoculation, and the antibody protective rates of the two groups of outer membrane protein vaccine of leptospira all were 100% at one month after immunization. Higher level antibody against L. icterohaemorrhagiae sero-group leptospira was still maintained at one year after injection. The results of cohort analysis showed that the protective rate of the outer envelope vaccine of leptospira for the same serological groups of leptospira was 75.17%, and the effective index of the vaccine was 4.03. The protective rate of vaccines obtained from 1:2 matched case-control studies was 81.25%, while that estimated by screening method was 75%. CONCLUSIONS: The study results showed that the serological and epidemiological efficiencies of leptospira vaccine all were ideal. In addition, this vaccine had partly protective effect against other sero-groups of leptospira.