res 55 179 stappenbeck t s hooper l v amp gordon j i 2002 proc natl acad sci usa 99 15451 15455 this assay employs confocal laser scanning microscopy of 120 u03bcm thick sections of intestine harvested from mice that have been subjected to ventricular perfusion with a solution of either fluroescein conjugated high molecular weight dextran or rhodamine b labeled gelatin two sets of comparisons may be made a adult germ free fvb n cr2 tox176 transgenic versus normal littermates i e animals without and with paneth cells in jejunal crypts respectively b adult germ free nmri mice versus age and gender matched ex germ free animals colonized for 10 and 35 d with an unfractionated ileal cecal microbiota purified angiogenin 4 can be assayed for bactericidal activity using conventional methods for instance it can be incubated with members of the normal intestinal flora e g e coli b thetaiotaomicron clostridium spp lactobacillus spp various intestinal pathogens e g s typhimurium shigella flexneri campylobacter jejuni a rnase with known bactericidal activity is suitably used as a positive control human eosinophil cationic protein lehrer r i et al 1989 j immunol 142 4428 4434 purified angiogenin 4 obtained as described in example 2 was assayed for bactericidal activity against several gram positive and gram negative intestinal pathogens and commensals the percentage of colony forming units cfus remaining after exposure to increasing concentrations of purified ang4 was determined and is shown in fig1 a bacteria were grown to mid log phase and resuspended in 10 mm sodium phosphate buffer ph 7 2 initial bacterial concentrations ranged from 10 5 to 10 6 cfu ml after incubation.