Figure 1.

 Agarose gel electrophoresis of polymerase chain reaction (PCR) products obtained from transmural bowel specimens following IS900 [L/AV] nested PCR (Crohn’s disease cases, two samples tested per case). Site of tissue sampling indicated as (C) colon, (R) rectum, and (IL) ileum. Lanes 1C, 2C, 3C, 4R, 5C, 6R, 7IL, 10IL, positive samples (+) with a specific amplification product of 298 bp. Lanes 8IL, 9IL, 11IL, 12IL, negative samples (−). Note variation in band intensity of the amplified products on the gels. Regarding lanes 5C and 10IL, both samples were positive. Positive controls consisted of a plasmid (pIDL60) containing a single copy of IS900. Inhibition controls consisted of pIDL60 “spiked” into each sample after processing.