Journal Article

OsteoSense, Animals; Fluorescence; Fluorescent Dyes/*diagnostic use; Guinea Pigs; Lymph Node Excision/*methods; Male; Models, Animal; *Molecular Imaging; Retroperitoneal Space

OBJECTIVES: To propose that fluorescent molecular imaging has utility in specifically identifying the lymph nodes, thereby enabling more definitive lymph node visualization and dissection. Retroperitoneal lymph node dissection (RPLND) is an invasive procedure with significant morbidity. A minimally invasive approach would be of great clinical benefit but has been limited by the extensive perivascular dissection required to remove all lymphatic tissue. Directed lymph node visualization would allow a limited dissection, making a laparoscopic approach more feasible. METHODS: Ten male Hartley guinea pigs underwent nonsurvival RPLND, 5 with the protease activatable in vivo fluorescent molecular imaging agent, ProSense and 5 without image guidance (control). ProSense was administered 24 hours before surgery and detected 24 hours later using a photodynamic detector. In group 1, RPLND was first performed without molecular imaging followed by image-guided lymph node dissection for residual nodes. In group 2, the near infrared detector was used initially for lymph node excision followed by traditionally unassisted extraction of the residual lymph nodes. The lymph nodes were extracted, counted, and sent for histopathologic analysis. RESULTS: With the assistance of molecular imaging, no additional lymph nodes were identified after complete dissection, and all tissue identified by ProSense was confirmed by histopathologic analysis to be lymph nodes. Without molecular imaging, all lymph nodes were not identified, and in 2 instances, the tissue was incorrectly thought to be lymphatic tissue. CONCLUSIONS: Molecular image-guided RPLND is a promising technique to improve in vivo, live visualization and dissection of lymph nodes and has the potential for application in improving the diagnosis and treatment of other urologic malignancies.

Journal Article

Abscess; Animals; Bacterial Proteins; Bioware; Culture Media; Disease Models, Animal; DNA Ligases; Female; Gene Expression Regulation, Bacterial; Genes, Essential; Humans; Isopropyl Thiogalactoside; Mice; Mutation; Staphylococcal Skin Infections; Staphylococcus aureus; Xen29

A conditional expression system has been developed using the isopropyl-beta-d-thiogalactopyranoside (IPTG)-inducible Pspac promoter to validate essential genes of Staphylococcus aureus in vivo. The system has been applied to prove the essentiality of ligA and to evaluate the function of tarI, which was found to be essential in vitro but not in vivo.

Journal Article

IVIS, Xen29, Xen 29, Staphylococcus aureus Xen29, Animals; Coagulase/metabolism; Endocarditis, Bacterial/*diagnosis; Mice; Microscopy, Fluorescence; Positron-Emission Tomography; Protein Engineering; Prothrombin/*diagnostic use/*metabolism; Quorum Sensing/physiology; Staphylococcus aureus/*metabolism/pathogenicity

Coagulase-positive Staphylococcus aureus (S. aureus) is the major causal pathogen of acute endocarditis, a rapidly progressing, destructive infection of the heart valves. Bacterial colonization occurs at sites of endothelial damage, where, together with fibrin and platelets, the bacteria initiate the formation of abnormal growths known as vegetations. Here we report that an engineered analog of prothrombin could be used to detect S. aureus in endocarditic vegetations via noninvasive fluorescence or positron emission tomography (PET) imaging. These prothrombin derivatives bound staphylocoagulase and intercalated into growing bacterial vegetations. We also present evidence for bacterial quorum sensing in the regulation of staphylocoagulase expression by S. aureus. Staphylocoagulase expression was limited to the growing edge of mature vegetations, where it was exposed to the host and co-localized with the imaging probe. When endocarditis was induced with an S. aureus strain with genetic deletion of coagulases, survival of mice improved, highlighting the role of staphylocoagulase as a virulence factor.

Journal Article

Abdominal Wall; Animals; Bioware; Female; Luminescent Measurements; Mice; Mice, Inbred BALB C; Polypropylenes; Polytetrafluoroethylene; pXen-5; Staphylococcal Infections; Staphylococcus aureus; Surgical Mesh; Xen29

OBJECTIVE To study the influence of morphology of surgical meshes on the course of bacterial infection under the influence of the host immune system in an in vivo chronic bacterial infection model. BACKGROUND The use of prosthetic meshes has increased dramatically the last decades in abdominal wall reconstructive surgery. Whereas infection is becoming a more frequent complication, attention is increasingly drawn to the influence of the surgeon's mesh choice on the course of this complication. METHODS Samples of 6 often applied surgical meshes were contaminated with a bioluminescent strain of Staphylococcus aureus and implanted subcutaneously in an immunocompetent BALB/c mouse. The intensity and the spreading of bioluminescence (ie, p/s/cm/sr) were analyzed non-invasively in vivo during a 10-day follow-up period. RESULTS Over the course of infection, multifilament polypropylene and hydrophobic materials showed a significantly higher persistence of bacteria as well as spreading of infection compared to all other meshes. In contrast, infection resolved in almost all animals with a low-weight polyester mesh. CONCLUSION The results of this study are in accordance with circumstantial evidence from limited clinical reports on infection involving surgical meshes and suggest that multifilament and hydrophobic meshes significantly increase bacterial persistence or spreading in the infected area in contrast to monofilament polypropylene and lightweight meshes. Therefore, the surgeon should consider this outcome when choosing a mesh graft for limiting infection in abdominal wall repair.

Journal Article

Animals, B16-F10-luc2, B16F10-luc2; Antibodies, Monoclonal/diagnostic use/immunology; *Diagnostic Imaging; Female; Fluorodeoxyglucose F18/diagnostic use; Glycoproteins/*immunology; Humans; Inflammation/*complications/immunology/pathology; Iodine Radioisotopes/diagnostic use/pharmacokinetics; Luminescent Measurements; Lymph Nodes/immunology/pathology/*radionuclide imaging; *Lymphangiogenesis; Lymphatic Metastasis; Melanoma, Experimental/*complications/immunology/pathology; Mice; Mice, Inbred C57BL; Mice, Transgenic; *Positron-Emission Tomography; Prognosis; Radiopharmaceuticals/diagnostic use; Skin/metabolism; Tissue Distribution; Vascular Endothelial Growth Factor C/metabolism; Vascular Endothelial Growth Factor Receptor-3/immunology

Metastasis to regional lymph nodes (LN) is a prognostic indicator for cancer progression. There is a great demand for sensitive and noninvasive methods to detect metastasis to LNs. Whereas conventional in vivo imaging approaches have focused on the detection of cancer cells, lymphangiogenesis within tumor-draining LNs might be the earliest sign of metastasis. In mouse models of LN lymphangiogenesis, we found that systemically injected antibodies to lymphatic epitopes accumulated in the lymphatic vasculature in tissues and LNs. Using a (124)I-labeled antibody against the lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), we imaged, for the first time, inflammation- and tumor-draining LNs with expanded lymphatic networks in vivo by positron emission tomography (PET). Anti-LYVE-1 immuno-PET enabled visualization of lymphatic vessel expansion in LNs bearing metastases that were not detected by [(18)F]fluorodeoxyglucose-PET, which is clinically applied to detect cancer metastases. Immuno-PET with lymphatic-specific antibodies may open up new avenues for the early detection of metastasis, and the images obtained might be used as biomarkers for the progression of diseases associated with lymphangiogenesis.