Faculty Bibliography

Delineation of tumor margins is a critical and challenging objective during brain cancer surgery. A tumor-targeting deep-blue nanoparticle-based visible contrast agent is described, which, for the first time, offers in vivo tumor-specific visible color staining. This technology thus enables color-guided tumor resection in real time, with no need for extra equipment or special lighting conditions. The visual contrast agent consists of polyacrylamide nanoparticles covalently linked to Coomassie Blue molecules (for nonleachable blue color contrast), which are surface-conjugated with polyethylene glycol and F3 peptides for efficient in vivo circulation and tumor targeting, respectively.

Thoracic vertebral compression fractures are a known complication of generalized tetanus. The authors report the first known case of an L-2 burst fracture leading to cauda equina syndrome, as a result of generalized tetanus. This 51-year-old man had generalized tetanus with a constellation of symptoms including compartment syndrome requiring fasciotomies, severe axial spasms and spasms of the extremities, autonomic dysreflexia, hypercarbic respiratory failure, and rhabdomyolysis. During the course of his illness, areflexic paraparesis developed in his lower extremities. He was found to have an L-2 burst fracture with retropulsion of a bone fragment resulting in cauda equina syndrome. Operative intervention was undertaken to decompress the cauda equina and stabilize the spine. The natural progression of tetanus can be complex, with a mixed picture ranging from spasms plus increased tone and reflexes to reduced tone and reflexes as presynaptic nerve terminals become damaged. The authors suggest that all sudden changes in the neurological examination should prompt consideration of diagnostic imaging before attributing such changes to natural progression of the disease.

Distinguishing a tumor from non-neoplastic tissue is a challenging task during cancer surgery. Several attempts have been made to use visible or fluorescent agents to aid in the visualization of a tumor during surgery. We describe a novel method to delineate brain tumors, using a highly sensitive photoacoustic imaging technique that is enhanced by tumor-targeting blue nanoparticles serving as a contrast agent. Experiments on phantoms and on rat brains, ex vivo, demonstrate the high sensitivity of photoacoustic imaging in delineating tumors containing contrast agent at a concentration much lower than needed for visualization by the naked eye. The limit of detection of the system for the nanoparticles is about 0.77 μg/mL in water (equivalent to 0.84 μmol/L Coomassie Blue dye). The present exploratory study suggests that photoacoustic imaging, when used with strongly optical absorbing contrast agents, could facilitate cancer surgery intraoperatively by revealing the distribution and extent of the tumor.

Methylene blue-conjugated polyacrylamide nanoparticles are prepared through a microemulsion polymerization, after conjugation of the dye with a monomer. The nanoparticles have a 50-60 nm diameter in solution. This conjugation method enables a large increase in loading of methylene blue per nanoparticle and also minimizes dye leaching out of the nanoparticle. Furthermore, the dye content can be controlled by variation of the dye amount, enabling a more refined control of the singlet oxygen production ability. The nanoparticles are coated with F3 peptides, which give specific targeting to selected tumor cells, 9L, MDA-MB-435, and F98, in vitro. In addition, MTT assays reveal that the nanoparticles have no dark toxicity but excellent PDT efficacy increasing with the nanoparticle dose and irradiation time.

Transorbital penetrating injury (TPI), an uncommon subset of head trauma, requires prompt multidisciplinary surgical intervention. While numerous case reports appear in the literature, there is a lack of discrete recommendations for initial evaluation, surgical intervention, and postoperative care of patients with TPI. A retrospective review of 4 cases of TPI at the University of Michigan Health System was undertaken to assess for diagnosis, treatment, and follow-up. In addition, a PubMed search using the terms "penetrating orbital trauma," "penetrating orbital injury," "transorbital penetration," and "transorbital penetrating injury" were used to search for articles discussing the presentation and management of penetrating orbital trauma. All 4 of the patients at the University of Michigan underwent focused physical examination performed by a multidisciplinary trauma team followed by dedicated maxillofacial and head CT scanning. The patients' treatments varied, depending on the mechanism and extent of the injury. An analysis of the case series presented here as well as other published cases suggests an algorithm for diagnosis and treatment for patients with TPI, which includes focused evaluation, diagnostic imaging with maxillofacial CT scanning, and management of the injury that focuses on the path of penetration and the presence of the foreign body in situ at the time of presentation. Magnetic resonance imaging is indicated in patients who have indwelling wooden foreign bodies. Angiography should be performed in patients with suspected vascular injury. Treatment decisions should be made by a multidisciplinary team with input from neurosurgery, ophthalmology, otolaryngology, and maxillofacial surgery.

The evaluation of candidate optical contrast agents for brain tumor delineation in ex vivo models may not accurately predict their activity in vivo. This study describes an in vivo model system designed to assess optical contrast agents for brain tumor delineation. The brain tumor window (BTW) model was created by performing biparietal craniectomies on 8-week-old Sprague-Dawley rats, injecting 9L glioma cells into the cortex and bonding a cover slip to the cranial defect with cyanoacrylate glue. Tumor growth was followed serially and occurred in an exponential fashion. Once tumors on the cortical surface achieved a 1mm radius, intravenous contrast agents were injected while the appearance of the cortical surface was recorded. Computerized image analysis was used to quantitatively evaluate visible differences between tumor and normal brain. Tumor margins became readily apparent following contrast administration in the BTW model. Based on red component intensity, tumor delineation improved fourfold at 50 min post-contrast administration in the BTW model (P<0.002). In summary, window placement overlying an implanted glioma is technically possible and well tolerated in the rat. The BTW model is a valid system for assessing the in vivo activity of optical contrast agents.

OBJECTIVE:Optical contrast agents for brain tumor delineation have been previously evaluated in ex vivo specimens from animals with implanted gliomas and may not reflect the true visual parameters encountered during surgery. This study describes a novel model system designed to evaluate optical contrast agents for tumor delineation in vivo. METHODS:Biparietal craniectomies were performed on 8-week-old Sprague-Dawley rats. 9L glioma cells were injected intraparenchymally. A cover slip was bonded to the cranial defect with cyanoacrylate glue. When the tumor radius reached 1 mm, Coomassie Blue was administered intravenously while the appearance of the cortical surface was recorded. Computerized image analysis of the red/green/blue color components was used to quantify visible differences between tumor and nonneoplastic tissue and to compare delineation in the brain tumor window (BTW) model with the conventional 9L glioma model. RESULTS:The tumor margin in the BTW model was poorly defined before contrast administration but readily apparent after contrast administration. Based on red component intensity, tumor delineation improved 4-fold at 50 minutes after contrast administration in the BTW model (P < .002). The conventional 9L glioma model overestimated the degree of delineation compared with the BTW model at the same dose of Coomassie Blue (P < .03). CONCLUSION/CONCLUSIONS:Window placement overlying an implanted glioma is technically possible and well tolerated in the rat. The BTW model is a valid system for evaluating optical contrast agents designed to delineate brain tumor margins. To our knowledge, we have described the first in vivo model system for evaluating optical contrast agents for tumor delineation.

BACKGROUND:Anterior cervical hyperosteophytosis describes the excessive formation of osteophytes along the ventral spine. Dysphagia due to ACH is considered an uncommon entity described mainly in case reports. Symptomatic ACH has been attributed to multiple etiologies including DISH, trauma, postlaminectomy syndromes, and cervical spondylosis. We report one of the largest series of patients with ACH-induced dysphagia requiring surgery. METHODS:After IRB approval, a retrospective chart review was completed. From 2001 to 2006, 9 patients presented with dysphagia due to ACH requiring surgical treatment. RESULTS:Eight patients were male, and the mean age was 65.1 years. Cervical spine x-rays and CT clearly demonstrated ACH in each case. Esophagram or a video fluoroscopic swallowing study was used to verify that dysphagia was caused by osteophytic overgrowth in all instances but one. In 2 patients, a focal osteophyte had formed adjacent to a previously fused segment. Of the remaining 7 patients, osteophytic formation was attributed to cervical spondylosis in 2 patients and DISH in 5 patients. All patients underwent osteophytectomy without spinal fusion. Average follow-up was 9.8 months. Although all 9 patients experienced resolution of dysphagia, improvement was delayed in 2 patients. CONCLUSIONS:Diffuse idiopathic skeletal hyperostosis and spondylosis are the most common etiologies accounting for ACH-induced dysphagia. Adjacent segment disease may also be a potential cause of symptomatic ACH and has not been previously reported. Regardless of etiology, surgical resection is highly successful if conservative measures fail.

OBJECTIVE:To synthesize and complete in vitro characterization of a novel, tumor-targeted nanodevice for visible intraoperative delineation of brain tumors. METHODS:The ability of dye-loaded polyacrylamide nanoparticles (NP) containing methylene blue, Coomassie blue, or indocyanine green to cause color change in the 9L glioma cell lines was evaluated. Cells were incubated with dye-loaded NPs, photographed, and analyzed colorimetrically. Confocal microscopy was used to determine subcellular localization of NPs in treated cells. RESULTS:Incubation of glioma cell lines with dye-loaded NPs resulted in clearly visible, quantifiable cell tagging in a dose- and time-dependent manner. Dye-loaded NPs were observed to bind to the surface and become internalized by glioma cells. Coating the NP surface with F3, a peptide that binds to the tumor cell surface receptor nucleolin, significantly increased NP affinity for glioma cells. F3 targeting also significantly increased the rate of cell tagging by dye-loaded NPs. Finally, F3-targeted NPs demonstrated specificity for targeting various cancer cell lines based on their surface expression of cell surface nucleolin. CONCLUSION/CONCLUSIONS:F3-targeted dye-loaded NPs efficiently cause definitive color change in glioma cells. This report represents the first use of targeted NPs to cause a visible color change in tumor cell lines. Similar nanodevices may be used in the future to enable visible intraoperative tumor delineation during tumor resection.

E2F-mediated control of gene expression is believed to have an essential role in the control of cellular proliferation. Using a conditional gene-targeting approach, we show that the targeted disruption of the entire E2F activator subclass composed of E2f1, E2f2, and E2f3 in mouse embryonic fibroblasts leads to the activation of p53 and the induction of p53 target genes, including p21(CIP1). Consequently, cyclin-dependent kinase activity and retinoblastoma (Rb) phosphorylation are dramatically inhibited, leading to Rb/E2F-mediated repression of E2F target gene expression and a severe block in cellular proliferation. Inactivation of p53 in E2f1-, E2f2-, and E2f3-deficient cells, either by spontaneous mutation or by conditional gene ablation, prevented the induction of p21(CIP1) and many other p53 target genes. As a result, cyclin-dependent kinase activity, Rb phosphorylation, and E2F target gene expression were restored to nearly normal levels, rendering cells responsive to normal growth signals. These findings suggest that a critical function of the E2F1, E2F2, and E2F3 activators is in the control of a p53-dependent axis that indirectly regulates E2F-mediated transcriptional repression and cellular proliferation.