Sequential, free and Y internal thoracic artery grafts.

The internal thoracic artery (ITA) has excellent durability and its ability to survive for 10 years or more far exceeds the saphenous vein graft (SVG). In an attempt to improve long-term survival from coronary artery bypass grafting (CABG), three or more (up to six) ITA coronary anastomoses have been placed in 718 patients since 1982. Initial flow in the ITA immediately after grafting is critical to the success of the operation. Careful dissection and preparation of the ITA pedicle to prevent injury and spasm, constructing parallel and perpendicular anastomoses so the most proximal portion of the ITA is used for anastomosis and the use of the free right ITA to increase length of graft available are measures employed to increase critical flow. Actuarial survival at 6 years is 92.5% in this group of patients, which includes elderly patients, patients with left ventricular dysfunction and patients undergoing emergency operations.

The complete nucleotide sequence of the lux regulon of Vibrio fischeri and the luxABN region of Photobacterium leiognathi and the mechanism of control of bacterial bioluminescence.

We have determined the complete nucleotide sequence of a 7622 base pair fragment of DNA from Vibrio fischeri strain ATCC7744 that contains all the information required to confer plasmid-borne, regulated bioluminescence upon strains of Escherichia coli. The lux regulon from V. fischeri consists of two divergently transcribed operons, L (left) and R (right), and at least seven genes, luxR (L operon) and luxICDABE (R operon) and the intervening control region. The luxA and luxB genes encode respectively the alpha and beta subunits of luciferase. The gene order luxCDABE seen in V. fischeri is the same as for V. harveyi. We have determined the sequence of the luxAB and flanking regions from Photobacterium leiognathi and have found upstream sequences homologous with luxC from the Vibrio species, but between luxB and luxE, there is an open reading frame encoding a protein of 227 amino acids (26,229 molecular weight) that is not found in this location in the Vibrio species. The amino terminal amino acid sequence of the encoded protein is nearly identical to that determined by O'Kane and Lee (University of Georgia) for the non-fluorescent flavoprotein from a closely related Photobacterium species (Dr Dennis O'Kane, personal communication). We have therefore designated this gene luxN. There is a 20-base inverted repeat ACCTGTAGGAxTCGTACAGGT, centred between bases 927 and 928 in the region between the two operons of V. fischeri. This region appears to fulfil two functions: it is critical for the LuxR protein to exert its effect and it is a consensus binding site for the E. coli LexA protein, a negative regulatory protein involved with the SOS response. There are sequences within the luxR coding region that appear to function in a cis-acting fashion to repress transcription from both the leftward and rightward promoters in the absence of the respective transcriptional activator proteins, thereby resulting in low basal levels of transcription. It now appears clear that there are multiple levels of control on the lux system allowing for a modulation of the intensity of bioluminescence of over four orders of magnitude.