Background-The presence of lymph node metastases is an important prognostic marker with regard to non-small-cell lung cancer (NSCLC). Assessment of the sentinel lymph node (SLN) for the presence of tumor may improve staging. Our objective was to develop an optical noninvasive imaging tool that would permit intraoperative SLN mapping and provide real-time visual feedback for image-guided localization and resection.

Objectives-With conventional methodology, sentinel lymph node (SLN) mapping of invasive urinary bladder cancer is technically challenging. This study was performed to determine the utility of invisible, near-infrared fluorescent (NIRF) light for patient-specific SLN mapping, in real time under complete image guidance.Methods-Lymphatic tracers, injection volume, NIRF excitation fluence rate, light collection of emitted fluorescence, and degree of bladder distension were systematically optimized in normal dogs and pigs. SLN mapping was then performed in pet dogs with naturally occurring invasive transitional cell carcinoma (InvTCC) of the urinary bladder, which closely mimics the human disease.Results-NIRF albumin (hydrodynamic diameter [HD], 7.4 nm) and NIRF quantum dots (15-20 nm HD) injected into the bladder wall resulted in identification of draining lymph nodes (LNs) in under 3 min. In both species, considerable variability in the lymphatic drainage was observed among individuals. Optimal SLN mapping was achieved with the use of superficial, serosal injection of NIRF tracer, with the bladder distended to an intraluminal pressure of 20-40 cm H 2 O. In dogs with InvTCC, NIRF tracers identified SLNs that were confirmed histologically to harbor metastases.Conclusions-The use of invisible NIRF light permits real-time, patient-specific identification of SLNs that drain bladder cancer. Intraluminal bladder pressure is a key parameter that needs to be controlled for optimal results. KeywordsBladder cancer; Fluorescence; Intraoperative imaging; Sentinel lymph node mapping * Corresponding author. Purdue University, Department of Veterinary Clinical Sciences, Lynn Hall of Veterinary Medicine, 625 Harrison St, West Lafayette, IN 47907-2026. Tel.765-494-9900; Fax: 765-496-1108. E-mail address: knappd@purdue.edu (D.W. Knapp). Take-home message This article describes successful use of intraoperative near-infrared light to identify sentinel lymph nodes (SLNs) draining invasive urinary bladder cancer in animals. This technology will permit studies of a new approach to identify SLNs at the time of cystectomy.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers

The recruitment of corepressors by DNA-bound repressors is likely to be a critical rate-limiting step in the transcriptional regulation of many genes. An excellent paradigm for such an interaction is the association of the basic helix-loop-helix zipper protein Mad1 with the corepressor mSin3A. When bound together, the Sin3 interaction domain (SID) of Mad1 forms extensive hydrophobic contacts with the four-helix bundle formed by the paired amphipathic helix 2 (PAH2) domain of mSin3A. Using the costructure to predict the principle residues required for binding, we have carried out an extensive mutational analysis to examine the Mad1 SID-mSin3A PAH2 interaction in vitro and in vivo. Bulky hydrophobic residues in the ␣1 (I308 and V311) and ␣2 (L329 and L332) helices of the PAH2 domain are necessary to accommodate the precise arrangement of bulky (L12) and short (A15 and A16) hydrophobic residues in the amphipathic Mad1 SID. We have also used phage display to derive an optimal SID, which shows an essentially identical arrangement of key residues. By manipulating these key residues, we have generated altered-specificity Mad1 SID mutants that bind only to a PAH2 domain with a reciprocal mutation, permitting us to demonstrate for the first time that these domains interact directly in vivo. We have also found that the integrity of the PAH1 domain affects the Mad1 SID-PAH2 interaction. It is conceivable that cross talk between different PAH domains and their binding partners helps to determine the subunit composition and order of assembly of mSin3A complexes.An important mechanistic link between transcriptional regulation and chromatin structure is the association of sequencespecific DNA-binding transcription factors with coactivators and corepressors (3,11,46,57). Coactivator and corepressor recruitment is generally considered to underlie the gene-specific alterations in chromatin structure that accompany changes in gene expression during differentiation, development, and oncogenesis. An emerging theme is that many different transcription factors recruit the same set of coactivators and corepressors. For example, transcriptional activation mediated by p53, c-Myb, CREB, MyoD, MEF2, and different nuclear hormone receptors, among others, involves recruitment of the coactivator p300 or CBP, each of which possesses and binds histone acetyltransferases (for a review, see reference 54). Similarly, corepressor complexes such as mSin3 and NURD have been found to interact with many DNA-binding repressors as well as with histone deacetylases (HDACs) and other factors involved in the modification of chromatin to a repressive state (for reviews, see references 4 and 28). Given this multiplicity of associations, both the nature and the specificity of the interactions between transcription factors and their coactivators and corepressors take on considerable importance.We have been studying the interactions between Mad proteins and the mSin3A corepressor complex. Mad family proteins (comprising Mad1, Mxi1, Mad3, and Mad4) belong to the ...

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