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Find video protocols related to scientific articles indexed in Pubmed.
Transferring biomarker into molecular probe: melanin nanoparticle as a naturally active platform for multimodality imaging.
J. Am. Chem. Soc.
PUBLISHED: 10-16-2014
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Developing multifunctional and easily prepared nanoplatforms with integrated different modalities is highly challenging for molecular imaging. Here, we report the successful transfer of an important molecular target, melanin, into a novel multimodality imaging nanoplatform. Melanin is abundantly expressed in melanotic melanomas and thus has been actively studied as a target for melanoma imaging. In our work, the multifunctional biopolymer nanoplatform based on ultrasmall (<10 nm) water-soluble melanin nanoparticle (MNP) was developed and showed unique photoacoustic property and natural binding ability with metal ions (for example, (64)Cu(2+), Fe(3+)). Therefore, MNP can serve not only as a photoacoustic contrast agent, but also as a nanoplatform for positron emission tomography (PET) and magnetic resonance imaging (MRI). Traditional passive nanoplatforms require complicated and time-consuming processes for prebuilding reporting moieties or chemical modifications using active groups to integrate different contrast properties into one entity. In comparison, utilizing functional biomarker melanin can greatly simplify the building process. We further conjugated ?v?3 integrins, cyclic c(RGDfC) peptide, to MNPs to allow for U87MG tumor accumulation due to its targeting property combined with the enhanced permeability and retention (EPR) effect. The multimodal properties of MNPs demonstrate the high potential of endogenous materials with multifunctions as nanoplatforms for molecular theranostics and clinical translation.
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Detection and quantitation of circulating tumor cell dynamics by bioluminescence imaging in an orthotopic mammary carcinoma model.
PLoS ONE
PUBLISHED: 09-04-2014
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Circulating tumor cells (CTCs) have been detected in the bloodstream of both early-stage and advanced cancer patients. However, very little is know about the dynamics of CTCs during cancer progression and the clinical relevance of longitudinal CTC enumeration. To address this, we developed a simple bioluminescence imaging assay to detect CTCs in mouse models of metastasis. In a 4T1 orthotopic metastatic mammary carcinoma mouse model, we demonstrated that this quantitative method offers sensitivity down to 2 CTCs in 0.1-1mL blood samples and high specificity for CTCs originating from the primary tumor, independently of their epithelial status. In this model, we simultaneously monitored blood CTC dynamics, primary tumor growth, and lung metastasis progression over the course of 24 days. Early in tumor development, we observed low numbers of CTCs in blood samples (10-15 cells/100 µL) and demonstrated that CTC dynamics correlate with viable primary tumor growth. To our knowledge, these data represent the first reported use of bioluminescence imaging to detect CTCs and quantify their dynamics in any cancer mouse model. This new assay is opening the door to the study of CTC dynamics in a variety of animal models. These studies may inform clinical decision on the appropriate timing of blood sampling and value of longitudinal CTC enumeration in cancer patients.
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(18)F-FPPRGD2 PET/CT: Pilot Phase Evaluation of Breast Cancer Patients.
Radiology
PUBLISHED: 07-16-2014
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Purpose To present data from the first prospective pilot phase trial of breast cancer participants imaged with fluorine 18 ((18)F)-2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid ( RGD arginine-glycine-aspartic acid ) peptide (PEG3-E[c{ RGD arginine-glycine-aspartic acid yk}]2) ( FPPRGD2 2-fluoropropionyl labeled PEGylated dimeric RGD peptide (PEG3-E[c{RGDyk}]2) ), a radiopharmaceutical agent used in positron emission tomographic (PET) imaging. Materials and Methods The local institutional review board approved the HIPAA-compliant protocol. Written informed consent was obtained from each patient. Eight women (age range, 44-67 years; mean age, 54.3 years ± 8.8 [standard deviation]) with newly diagnosed or recurrent breast cancer were recruited between November 2010 and February 2011. (18)F- FPPRGD2 2-fluoropropionyl labeled PEGylated dimeric RGD peptide (PEG3-E[c{RGDyk}]2) PET/computed tomographic (CT) and (18)F-fluorodeoxyglucose ( FDG fluorine 18 fluorodeoxyglucose ) PET/CT examinations were performed within 3 weeks of each other. Dynamic (18)F- FPPRGD2 2-fluoropropionyl labeled PEGylated dimeric RGD peptide (PEG3-E[c{RGDyk}]2) PET and two whole-body static (18)F- FPPRGD2 2-fluoropropionyl labeled PEGylated dimeric RGD peptide (PEG3-E[c{RGDyk}]2) PET/CT scans were obtained. During this time, vital signs and electrocardiograms were recorded at regular intervals. Blood samples were obtained before the injection of (18)F- FPPRGD2 2-fluoropropionyl labeled PEGylated dimeric RGD peptide (PEG3-E[c{RGDyk}]2) and at 24 hours and 1 week after injection to evaluate for toxicity. A nonparametric version of multivariate analysis of variance was used to assess the safety outcome measures simultaneously across time points. A paired two-sample t test was performed to compare the maximum standardized uptake values ( SUVmax maximum standardized uptake value ). Results (18)F- FPPRGD2 2-fluoropropionyl labeled PEGylated dimeric RGD peptide (PEG3-E[c{RGDyk}]2) was well tolerated, without noticeable changes in vital signs, on electrocardiograms, or in laboratory values. A total of 30 lesions were evaluated at (18)F- FDG fluorine 18 fluorodeoxyglucose PET/CT and (18)F- FPPRGD2 2-fluoropropionyl labeled PEGylated dimeric RGD peptide (PEG3-E[c{RGDyk}]2) PET/CT. The primary breast lesions had (18)F- FPPRGD2 2-fluoropropionyl labeled PEGylated dimeric RGD peptide (PEG3-E[c{RGDyk}]2) uptake with SUVmax maximum standardized uptake value of 2.4-9.4 (mean, 5.6 ± 2.8) 60 minutes after injection, compared with (18)F- FDG fluorine 18 fluorodeoxyglucose uptake with SUVmax maximum standardized uptake value of 2.8-18.6 (mean, 10.4 ± 7.2). Metastatic lesions also showed (18)F- FPPRGD2 2-fluoropropionyl labeled PEGylated dimeric RGD peptide (PEG3-E[c{RGDyk}]2) uptake, with SUVmax maximum standardized uptake value of 2.4-9.7 (mean, 5.0 ± 2.3) at 60 minutes, compared with (18)F- FDG fluorine 18 fluorodeoxyglucose uptake with SUVmax maximum standardized uptake value of 2.2-14.6 (mean, 6.6 ± 4.2). Conclusion Data from this pilot phase study suggest that (18)F- FPPRGD2 2-fluoropropionyl labeled PEGylated dimeric RGD peptide (PEG3-E[c{RGDyk}]2) is a safe PET radiopharmaceutical agent. Evaluation of (18)F- FPPRGD2 2-fluoropropionyl labeled PEGylated dimeric RGD peptide (PEG3-E[c{RGDyk}]2) in participants with breast cancer demonstrated significant uptake in the primary lesion and in the metastases. Larger cohorts are required to confirm these preliminary findings. © RSNA, 2014.
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A Radiofluorinated Divalent Cystine Knot Peptide for Tumor PET Imaging.
Mol. Pharm.
PUBLISHED: 04-28-2014
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A divalent knottin containing two separate integrin binding epitopes (RGD) in the adjacent loops, 3-4A, was recently developed and reported in our previous publication. In the current study, 3-4A was radiofluorinated with a 4-nitrophenyl 2-(18)F-fluoropropinate ((18)F-NFP) group and the resulting divalent positron emission tomography (PET) probe, (18)F-FP-3-4A, was evaluated as a novel imaging probe to detect integrin ?v?3 positive tumors in living animals. Knottin 3-4A was synthesized by solid phase peptide synthesis, folded, and site-specifically conjugated with (18/19)F-NFP to produce the fluorinated peptide (18/19)F-fluoropropinate-3-4A ((18/19)F-FP-3-4A). The stability of (18)F-FP-3-4A was tested in both phosphate buffered saline (PBS) buffer and mouse serum. Cell uptake assays of the radiolabeled peptides were performed using U87MG cells. In addition, small animal PET imaging and biodistribution studies of (18)F-FP-3-4A were performed in U87MG tumor-bearing mice. The receptor targeting specificity of the radiolabeled peptide was also verified by coinjecting the probe with a blocking peptide cyclo(RGDyK). Our study showed that (18)F-FP-3-4A exhibited excellent stability in PBS buffer (pH 7.4) and mouse serum. Small animal PET imaging and biodistribution data revealed that (18)F-FP-3-4A exhibited rapid and good tumor uptake (3.76 ± 0.59% ID/g and 2.22 ± 0.62% ID/g at 0.5 and 1 h, respectively). (18)F-FP-3-4A was rapidly cleared from the normal tissues, resulting in excellent tumor-to-normal tissue contrasts. For example, liver uptake was only 0.39 ± 0.07% ID/g and the tumor to liver ratio was 5.69 at 1 h p.i. Furthermore, coinjection of cyclo(RGDyK) with (18)F-FP-3-4A significantly inhibited tumor uptake (0.41 ± 0.12 vs 1.02 ± 0.19% ID/g at 2.5 h) in U87MG xenograft models, demonstrating specific accumulation of the probe in the tumor. In summary, the divalent probe (18)F-FP-3-4A is characterized by rapid and high tumor uptake and excellent tumor-to-normal tissue ratios. (18)F-FP-3-4A is a highly promising knottin based PET probe for translating into clinical imaging of tumor angiogenesis.
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Selective uptake of single-walled carbon nanotubes by circulating monocytes for enhanced tumour delivery.
Nat Nanotechnol
PUBLISHED: 02-26-2014
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In cancer imaging, nanoparticle biodistribution is typically visualized in living subjects using 'bulk' imaging modalities such as magnetic resonance imaging, computerized tomography and whole-body fluorescence. Accordingly, nanoparticle influx is observed only macroscopically, and the mechanisms by which they target cancer remain elusive. Nanoparticles are assumed to accumulate via several targeting mechanisms, particularly extravasation (leakage into tumour). Here, we show that, in addition to conventional nanoparticle-uptake mechanisms, single-walled carbon nanotubes are almost exclusively taken up by a single immune cell subset, Ly-6C(hi) monocytes (almost 100% uptake in Ly-6C(hi) monocytes, below 3% in all other circulating cells), and delivered to the tumour in mice. We also demonstrate that a targeting ligand (RGD) conjugated to nanotubes significantly enhances the number of single-walled carbon nanotube-loaded monocytes reaching the tumour (P < 0.001, day 7 post-injection). The remarkable selectivity of this tumour-targeting mechanism demonstrates an advanced immune-based delivery strategy for enhancing specific tumour delivery with substantial penetration.
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99mTc-labeled cystine knot peptide targeting integrin ?v?6 for tumor SPECT imaging.
Mol. Pharm.
PUBLISHED: 02-24-2014
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Integrin ?v?6 is overexpressed in a variety of cancers, and its expression is often associated with poor prognosis. Therefore, there is a need to develop affinity reagents for noninvasive imaging of integrin ?v?6 expression since it may provide early cancer diagnosis, more accurate prognosis, and better treatment planning. We recently engineered and validated highly stable cystine knot peptides that selectively bind integrin ?v?6 with no cross-reactivity to integrins ?v?5, ?5?1, or ?v?3, also known to be overexpressed in many cancers. Here, we developed a single photon emission computed tomography (SPECT) probe for imaging integrin ?v?6 positive tumors. Cystine knot peptide, S02, was first conjugated with a single amino acid chelate (SAAC) and labeled with [(99m)Tc(H2O)3(CO)3](+). The resulting probe, (99m)Tc-SAAC-S02, was then evaluated by in vitro cell uptake studies using two ?v?6 positive cell lines (human lung adenocarcinoma cell line HCC4006 and pancreatic cancer cell line BxPC-3) and two ?v?6 negative cell lines (human lung adenocarcinoma cell line H838 and human embryonic kidney cell line 293T). Next, SPECT/CT and biodistribution studies were performed in nude mice bearing HCC4006 and H838 tumor xenografts to evaluate the in vivo performance of (99m)Tc-SAAC-S02. Significant differences in the uptake of (99m)Tc-SAAC-S02 were observed in ?v?6 positive vs negative cells (P < 0.05). Biodistribution and small animal SPECT/CT studies revealed that (99m)Tc-SAAC-S02 accumulated to moderate levels in antigen positive tumors (?2% ID/g at 1 and 6 h postinjection, n = 3 or 4/group). Moreover, the probe demonstrated tumor-to-background tissue ratios of 6.81 ± 2.32 (tumor-to-muscle) and 1.63 ± 0.18 (tumor-to-blood) at 6 h postinjection in ?v?6 positive tumor xenografts. Co-incubation of the probe with excess amount of unlabeled S02 as a blocking agent demonstrated significantly reduced tumor uptake, which is consistent with specific binding to the target. Renal filtration was the main route of clearance. In conclusion, knottin peptides are excellent scaffolds for which to develop highly stable imaging probes for a variety of oncological targets. (99m)Tc-SAAC-S02 demonstrates promise for use as a SPECT agent to image integrin ?v?6 expression in living systems.
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Ultrasound molecular imaging in a human CD276 expression-modulated murine ovarian cancer model.
Clin. Cancer Res.
PUBLISHED: 01-03-2014
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To develop a mouse ovarian cancer model that allows modulating the expression levels of human vascular targets in mouse xenograft tumors and to test whether expression of CD276 during tumor angiogenesis can be visualized by molecularly targeted ultrasound in vivo.
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Investigation of 6-[¹?F]-fluoromaltose as a novel PET tracer for imaging bacterial infection.
PLoS ONE
PUBLISHED: 01-01-2014
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Despite advances in the field of nuclear medicine, the imaging of bacterial infections has remained a challenge. The existing reagents suffer from poor sensitivity and specificity. In this study we investigate the potential of a novel PET (positron emission tomography) tracer that overcomes these limitations.
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Imaging circulating tumor cells in freely moving awake small animals using a miniaturized intravital microscope.
PLoS ONE
PUBLISHED: 01-01-2014
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Metastasis, the cause for 90% of cancer mortality, is a complex and poorly understood process involving the invasion of circulating tumor cells (CTCs) into blood vessels. These cells have potential prognostic value as biomarkers for early metastatic risk. But their rarity and the lack of specificity and sensitivity in measuring them render their interrogation by current techniques very challenging. How and when these cells are circulating in the blood, on their way to potentially give rise to metastasis, is a question that remains largely unanswered. In order to provide an insight into this "black box" using non-invasive imaging, we developed a novel miniature intravital microscopy (mIVM) strategy capable of real-time long-term monitoring of CTCs in awake small animals. We established an experimental 4T1-GL mouse model of metastatic breast cancer, in which tumor cells express both fluorescent and bioluminescent reporter genes to enable both single cell and whole body tumor imaging. Using mIVM, we monitored blood vessels of different diameters in awake mice in an experimental model of metastasis. Using an in-house software algorithm we developed, we demonstrated in vivo CTC enumeration and computation of CTC trajectory and speed. These data represent the first reported use we know of for a miniature mountable intravital microscopy setup for in vivo imaging of CTCs in awake animals.
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High-resolution, serial intravital microscopic imaging of nanoparticle delivery and targeting in a small animal tumor model.
Nano Today
PUBLISHED: 11-26-2013
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Nanoparticles are under active investigation for the detection and treatment of cancer. Yet our understanding of nanoparticle delivery to tumors is limited by our ability to observe the uptake process on its own scale in living subjects. We chose to study single-walled carbon nanotubes (SWNTs) because they exhibit among the highest levels of tumor uptake across the wide variety of available nanoparticles. We target them using RGD (arginine-glycine-aspartic acid) peptide which directs them to integrins overexpressed on tumor vasculature and on the surface of some tumor cells (e.g., U87MG as used here). We employ intravital microscopy (IVM) to quantitatively examine the spatiotemporal framework of targeted SWNT uptake in a murine tumor model. IVM provided a dynamic microscale window into nanoparticle circulation, binding to tumor blood vessels, extravasation, binding to tumor cells, and tumor retention. RGD-SWNTs bound to tumor vasculature significantly more than controls (P<0.0001). RGD-SWNTs extravasated similarly compared to control RAD-SWNTs, but post-extravasation we observed as RGD-SWNTs eventually bound to individual tumor cells significantly more than RAD-SWNTs (p<0.0001) over time. RGD-SWNTs and RAD-SWNTs displayed similar signal in tumor for a week, but over time their curves significantly diverged (p<0.001) showing increasing RGD-SWNTs relative to untargeted SWNTs. We uncovered the complex spatiotemporal interplay between these competing uptake mechanisms. Specific uptake was delimited to early (1-6 hours) and late (1-4 weeks) time-points, while non-specific uptake dominated from 6 hours to 1 week. Our analysis revealed critical, quantitative insights into the dynamic, multifaceted mechanisms implicated in ligand-targeted SWNT accumulation in tumor using real-time observation.
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A Novel Engineered Anti-CD20 Tracer Enables Early Time PET Imaging in a Humanized Transgenic Mouse Model of B-cell Non-Hodgkins Lymphoma.
Clin. Cancer Res.
PUBLISHED: 10-04-2013
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The aim of this article was to evaluate the use of a novel engineered anti-CD20 protein based on the 10 kDa human fibronectin type 3 domain (FN3) and subsequently compare with (64)Cu-rituximab for positron emission tomography (PET) imaging of CD20.
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Imaging tumor angiogenesis: the road to clinical utility.
AJR Am J Roentgenol
PUBLISHED: 07-26-2013
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Tumor growth and progression require the formation of new blood vessels from preexisting vasculature, a process called angiogenesis. The ability to noninvasively visualize angiogenesis may provide new opportunities to more appropriately select patients for antiangiogenesis treatment and to monitor treatment efficacy.
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Evaluation of 89Zr-rituximab tracer by Cerenkov luminescence imaging and correlation with PET in a humanized transgenic mouse model to image NHL.
Mol Imaging Biol
PUBLISHED: 03-09-2013
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This research aimed to study the use of Cerenkov luminescence imaging (CLI) for non-Hodgkins lymphoma (NHL) using 89Zr-rituximab positron emission tomography (PET) tracer with a humanized transgenic mouse model that expresses human CD20 and the correlation of CLI with PET.
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Pilot prospective evaluation of 99mTc-MDP scintigraphy, 18F NaF PET/CT, 18F FDG PET/CT and whole-body MRI for detection of skeletal metastases.
Clin Nucl Med
PUBLISHED: 03-05-2013
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The aim of this study was to compare 99mTc-MDP bone scanning, 18F NaF PET/CT, 18F FDG PET/CT, and whole-body MRI (WBMRI) for detection of known osseous metastases.
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Single-cell photonic nanocavity probes.
Nano Lett.
PUBLISHED: 02-14-2013
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In this report, we demonstrate for the first time photonic nanocavities operating inside single biological cells. Here we develop a nanobeam photonic crystal (PC) cavity as an advanced cellular nanoprobe, active in nature, and configurable to provide a multitude of actions for both intracellular sensing and control. Our semiconductor nanocavity probes emit photoluminescence (PL) from embedded quantum dots (QD) and sustain high quality resonant photonic modes inside cells. The probes are shown to be minimally cytotoxic to cells from viability studies, and the beams can be loaded in cells and tracked for days at a time, with cells undergoing regular division with the beams. We present in vitro label-free protein sensing with our probes to detect streptavidin as a path towards real-time biomarker and biomolecule detection inside single cells. The results of this work will enable new areas of research merging the strengths of photonic nanocavities with fundamental cell biology.
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Molecular photoacoustic imaging of follicular thyroid carcinoma.
Clin. Cancer Res.
PUBLISHED: 01-24-2013
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To evaluate the potential of targeted photoacoustic imaging as a noninvasive method for detection of follicular thyroid carcinoma.
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Non-invasive imaging of phosphoinositide-3-kinase-catalytic-subunit-alpha (PIK3CA) promoter modulation in small animal models.
PLoS ONE
PUBLISHED: 01-04-2013
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Activation of the PI3K/Akt pathway, a critical step for survival in cancer cells is often associated with decreased sensitivity to several chemotherapeutic drugs. PIK3CA gene amplification is observed in 16-24% of epithelial ovarian cancer (EOC) patients in conjunction with p53 mutations. A 900 bp long PIK3CA promoter is shown to be negatively regulated by p53 in ovarian surface epithelial cells but the consequence of chemotherapeutic drug treatments on this promoter in ovarian cancer cells is largely unknown. We aim to study the modulation of this promoter by cisplatin using an improved fusion reporter in ovarian cancer cells and tumor xenografts by non-invasive imaging approach. A PIK3CA sensor was developed using a bi-fusion reporter from a newly constructed library of bi- and tri-fusion vectors comprising of two mutant far red fluorescent proteins (mcherry/mch and tdTomato/tdt), a mutant firefly luciferase (fluc2), and a PET reporter protein (ttk). In vivo imaging of mice implanted with 293T cells transiently expressing these bi- and tri-fusion reporters along with respective controls revealed comparable activity of each reporter in the fusion background and fluc2-tdt as the most sensitive one. Repression of the PIK3CA sensor by drugs was inversely proportional to cellular p53 level in a germline (PA1) and in an EOC (A2780) cell line but not in a p53 deficient EOC (SKOV3) cell line. Bioluminescence imaging of tumor xenografts stably expressing the PIK3CA sensor in PA1 and A2780 cells exhibited attenuating activity without any change in SKOV3 tumors expressing the PIK3CA sensor after cisplatin treatment. Sequential mutation at p53 binding sites showed gradual increase in promoter activity and decreased effects of the drugs. These newly developed PIK3CA-fluc2-tdt and the mutant reporter sensors thus would be extremely useful for screening new drugs and for functional assessment of PIK3CA expression from intact cells to living subjects.
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Development and validation of non-integrative, self-limited, and replicating minicircles for safe reporter gene imaging of cell-based therapies.
PLoS ONE
PUBLISHED: 01-01-2013
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Reporter gene (RG) imaging of cell-based therapies provides a direct readout of therapeutic efficacy by assessing the fate of implanted cells. To permit long-term cellular imaging, RGs are traditionally required to be integrated into the cellular genome. This poses a potential safety risk and regulatory bottleneck for clinical translation as integration can lead to cellular transformation. To address this issue, we have developed non-integrative, replicating minicircles (MCs) as an alternative platform for safer monitoring of cells in living subjects. We developed both plasmids and minicircles containing the scaffold/matrix attachment regions (S/MAR) of the human interferon-beta gene, driven by the CMV promoter, and expressing the bioluminescence RG firefly luciferase. Constructs were transfected into breast cancer cells, and expanded S/MAR minicircle clones showed luciferase signal for greater than 3 months in culture and minicircles remained as episomes. Importantly, luciferase activity in clonal populations was slowly lost over time and this corresponded to a loss of episome, providing a way to reversibly label cells. To monitor cell proliferation in vivo, 1.5 × 10(6) cells carrying the S/MAR minicircle were implanted subcutaneously into mice (n = 5) and as tumors developed significantly more bioluminescence signal was noted at day 35 and 43 compared to day 7 post-implant (p<0.05). To our knowledge, this is the first work examining the use of episomal, self-limited, replicating minicircles to track the proliferation of cells using non-invasive imaging in living subjects. Continued development of S/MAR minicircles will provide a broadly applicable vector platform amenable with any of the numerous RG technologies available to allow therapeutic cell fate to be assessed in individual patients, and to achieve this without the need to manipulate the cells genome so that safety concerns are minimized. This will lead to safe tools to assess treatment response at earlier time points and improve the precision of cell-based therapies.
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Immunomodulation of curcumin on adoptive therapy with T cell functional imaging in mice.
Cancer Prev Res (Phila)
PUBLISHED: 12-01-2011
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Adoptive T-cell therapy involves the ex vivo expansion and subsequent transfusion of tumor-specific T lymphocytes to eliminate tumors. Using immune modulators to block immunosuppressive factors in the tumor microenvironment has emerged as a promising strategy to enhance T-cell-mediated tumor regression. Curcumin, a major component of turmeric, has been shown to possess antitumor and immunomodulatory effects by regulating a diverse range of molecular targets. Thus, we hypothesize that these beneficial effects of curcumin may improve the therapeutic efficacy of adoptive therapy. Here, we have shown that curcumin enhances cytotoxicity of CD8(+) T cells toward tumors via alteration of the tumor microenvironment when combined with adoptive therapy. We found that T-cell accumulation and function were increased in combined treatment due to the blockade of different immunosuppressors, including TGF-?, indoleamine 2,3-dioxygenase, and regulatory T cells. Furthermore, bioluminescent imaging with a granzyme B promoter-conjugated optical reporter also reflected improved cytotoxicity of antigen-specific CD8(+) T cells in tumor-bearing mice during treatment. These findings suggest that combination of multitargeting drugs, such as curcumin, with adoptive therapy may have potential for clinical application. In addition, using a granzyme B-specific imaging reporter to assess T-cell function may also be applied for the development and therapeutic evaluation of new immunotherapy in preclinical studies.
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Synthesis of 2-deoxy-2-[18F]fluoro-9-?-D-arabinofuranosylguanine: a novel agent for imaging T-cell activation with PET.
Mol Imaging Biol
PUBLISHED: 11-11-2011
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9-(?-D-Arabinofuranosyl)guanine (AraG) is a guanosine analog that has a proven efficacy in the treatment of T-cell lymphoblastic disease. To test the possibility of using a radiofluorinated AraG as an imaging agent, we have synthesized 2-deoxy-2-[(18)F]fluoro-9-?-D-arabinofuranosylguanine ([(18)F]F-AraG) and investigated its uptake in T cells.
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A hybrid least squares and principal component analysis algorithm for Raman spectroscopy.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 08-29-2011
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The least squares fitting algorithm is the most commonly used algorithm in Raman spectroscopy. In this paper, however, we show that it is sensitive to variations in the background signal when the signal of interest is weak. To address this problem, we propose a novel algorithm to analyze measured spectra in Raman spectroscopy. The method is a hybrid least squares and principal component analysis algorithm. It explicitly accounts for any variations expected in the reference spectra used in the signal decomposition. We compare the novel algorithm to the least squares method with a low-order polynomial residual model, and demonstrate the novel algorithms superior performance by comparing quantitative error metrics. Our experiments use both simulated data and data acquired from an in vitro solution of Raman-enhanced gold nanoparticles.
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Non-invasive imaging of cysteine cathepsin activity in solid tumors using a 64Cu-labeled activity-based probe.
PLoS ONE
PUBLISHED: 08-23-2011
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The papain family of cysteine cathepsins are actively involved in multiple stages of tumorigenesis. Because elevated cathepsin activity can be found in many types of human cancers, they are promising biomarkers that can be used to target radiological contrast agents for tumor detection. However, currently there are no radiological imaging agents available for these important molecular targets. We report here the development of positron emission tomography (PET) radionuclide-labeled probes that target the cysteine cathepsins by formation of an enzyme activity-dependent bond with the active site cysteine. These probes contain an acyloxymethyl ketone (AOMK) functional group that irreversibly labels the active site cysteine of papain family proteases attached to a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) tag for labeling with (64)Cu for PET imaging studies. We performed biodistribution and microPET imaging studies in nude mice bearing subcutaneous tumors expressing various levels of cysteine cathepsin activity and found that the extent of probe uptake by tumors correlated with overall protease activity as measured by biochemical methods. Furthermore, probe signals could be reduced by pre-treatment with a general cathepsin inhibitor. We also found that inclusion of a Cy5 tag on the probe increased tumor uptake relative to probes lacking this fluorogenic dye. Overall, these results demonstrate that small molecule activity-based probes carrying radio-tracers can be used to image protease activity in living subjects.
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Prospective comparison of combined 18F-FDG and 18F-NaF PET/CT vs. 18F-FDG PET/CT imaging for detection of malignancy.
Eur. J. Nucl. Med. Mol. Imaging
PUBLISHED: 07-07-2011
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Typically, (18)F-FDG PET/CT and (18)F-NaF PET/CT scans are done as two separate studies on different days to allow sufficient time for the radiopharmaceutical from the first study to decay. This is inconvenient for the patients and exposes them to two doses of radiation from the CT component of the examinations. In the current study, we compared the clinical usefulness of a combined (18)F-FDG/(18)F-NaF PET/CT scan with that of a separate (18)F-FDG-only PET/CT scan.
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Multimodality imaging of ?-cells in mouse models of type 1 and 2 diabetes.
Diabetes
PUBLISHED: 03-25-2011
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?-Cells that express an imaging reporter have provided powerful tools for studying ?-cell development, islet transplantation, and ?-cell autoimmunity. To further expedite diabetes research, we generated transgenic C57BL/6 "MIP-TF" mice that have a mouse insulin promoter (MIP) driving the expression of a trifusion (TF) protein of three imaging reporters (luciferase/enhanced green fluorescent protein/HSV1-sr39 thymidine kinase) in their ?-cells. This should enable the noninvasive imaging of ?-cells by charge-coupled device (CCD) and micro-positron emission tomography (PET), as well as the identification of ?-cells at the cellular level by fluorescent microscopy.
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MYC phosphorylation, activation, and tumorigenic potential in hepatocellular carcinoma are regulated by HMG-CoA reductase.
Cancer Res.
PUBLISHED: 01-24-2011
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MYC is a potential target for many cancers but is not amenable to existing pharmacologic approaches. Inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase) by statins has shown potential efficacy against a number of cancers. Here, we show that inhibition of HMG-CoA reductase by atorvastatin (AT) blocks both MYC phosphorylation and activation, suppressing tumor initiation and growth in vivo in a transgenic model of MYC-induced hepatocellular carcinoma (HCC) as well as in human HCC-derived cell lines. To confirm specificity, we show that the antitumor effects of AT are blocked by cotreatment with the HMG-CoA reductase product mevalonate. Moreover, by using a novel molecular imaging sensor, we confirm that inhibition of HMG-CoA reductase blocks MYC phosphorylation in vivo. Importantly, the introduction of phosphorylation mutants of MYC at Ser62 or Thr58 into tumors blocks their sensitivity to inhibition of HMG-CoA reductase. Finally, we show that inhibition of HMG-CoA reductase suppresses MYC phosphorylation through Rac GTPase. Therefore, HMG-CoA reductase is a critical regulator of MYC phosphorylation, activation, and tumorigenic properties. The inhibition of HMG-CoA reductase may be a useful target for the treatment of MYC-associated HCC as well as other tumors.
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Cancer stem cells from human breast tumors are involved in spontaneous metastases in orthotopic mouse models.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 10-04-2010
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To examine the role of breast cancer stem cells (BCSCs) in metastasis, we generated human-in-mouse breast cancer orthotopic models using patient tumor specimens, labeled with optical reporter fusion genes. These models recapitulate human cancer features not captured with previous models, including spontaneous metastasis in particular, and provide a useful platform for studies of breast tumor initiation and progression. With noninvasive imaging approaches, as few as 10 cells of stably labeled BCSCs could be tracked in vivo, enabling studies of early tumor growth and spontaneous metastasis. These advances in BCSC imaging revealed that CD44(+) cells from both primary tumors and lung metastases are highly enriched for tumor-initiating cells. Our metastatic cancer models, combined with noninvasive imaging techniques, constitute an integrated approach that could be applied to dissect the molecular mechanisms underlying the dissemination of metastatic CSCs (MCSCs) and to explore therapeutic strategies targeting MCSCs in general or to evaluate individual patient tumor cells and predict response to therapy.
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Design, synthesis, and imaging of an activatable photoacoustic probe.
J. Am. Chem. Soc.
PUBLISHED: 08-12-2010
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Photoacoustic tomography is a rapidly growing imaging modality that can provide images of high spatial resolution and high contrast at depths up to 5 cm. We report here the design, synthesis, and evaluation of an activatable probe that shows great promise for enabling detection of the cleaved probe in the presence of high levels of nonactivated, uncleaved probe, a difficult task to attain in absorbance-based modality. Before the cleavage by its target, proteolytic enzyme MMP-2, the probe, an activatable cell-penetrating peptide, Ceeee[Ahx]PLGLAGrrrrrK, labeled with two chromophores, BHQ3 and Alexa750, shows photoacoustic signals of similar intensity at the two wavelengths corresponding to the absorption maxima of the chromophores, 675 and 750 nm. Subtraction of the images taken at these two wavelengths makes the probe effectively photoacoustically silent, as the signals at these two wavelengths essentially cancel out. After the cleavage, the dye associated with the cell-penetrating part of the probe, BHQ3, accumulates in the cells, while the other dye diffuses away, resulting in photoacoustic signal seen at only one of the wavelengths, 675 nm. Subtraction of the photoacoustic images at two wavelengths reveals the location of the cleaved (activated) probe. In the search for the chromophores that are best suited for photoacoustic imaging, we have investigated the photoacoustic signals of five chromophores absorbing in the near-infrared region. We have found that the photoacoustic signal did not correlate with the absorbance and fluorescence of the molecules, as the highest photoacoustic signal arose from the least absorbing quenchers, BHQ3 and QXL 680.
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Near-infrared fluorescent nanoprobes for cancer molecular imaging: status and challenges.
Trends Mol Med
PUBLISHED: 06-22-2010
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Near-infrared fluorescence (NIRF) imaging promises to improve cancer imaging and management; advances in nanomaterials allow scientists to combine new nanoparticles with NIRF imaging techniques, thereby fulfilling this promise. Here, we present a synopsis of current developments in NIRF nanoprobes, their use in imaging small living subjects, their pharmacokinetics and toxicity, and finally their integration into multimodal imaging strategies. We also discuss challenges impeding the clinical translation of NIRF nanoprobes for molecular imaging of cancer. Whereas utilization of most NIRF nanoprobes remains at a proof-of-principle stage, optimizing the impact of nanomedicine in cancer patient diagnosis and management will probably be realized through persistent interdisciplinary amalgamation of diverse research fields.
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Ultrahigh sensitivity carbon nanotube agents for photoacoustic molecular imaging in living mice.
Nano Lett.
PUBLISHED: 05-27-2010
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Photoacoustic imaging is an emerging modality that overcomes to a great extent the resolution and depth limitations of optical imaging while maintaining relatively high-contrast. However, since many diseases will not manifest an endogenous photoacoustic contrast, it is essential to develop exogenous photoacoustic contrast agents that can target diseased tissue(s). Here we present a novel photoacoustic contrast agent, Indocyanine Green dye-enhanced single walled carbon nanotube (SWNT-ICG). We conjugated this contrast agent with cyclic Arg-Gly-Asp (RGD) peptides to molecularly target the alpha(v)beta(3) integrins, which are associated with tumor angiogenesis. Intravenous administration of this tumor-targeted contrast agent to tumor-bearing mice showed significantly higher photoacoustic signal in the tumor than in mice injected with the untargeted contrast agent. The new contrast agent gave a markedly 300 times higher photoacoustic contrast in living tissues than previously reported SWNTs, leading to subnanomolar sensitivities. Finally, we show that the new contrast agent can detect approximately 20 times fewer cancer cells than previously reported SWNTs.
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Cetuximab-based immunotherapy and radioimmunotherapy of head and neck squamous cell carcinoma.
Clin. Cancer Res.
PUBLISHED: 03-09-2010
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To show the relationship between antibody delivery and therapeutic efficacy in head and neck cancers, in this study we evaluated the pharmacokinetics and pharmacodynamics of epidermal growth factor receptor (EGFR)-targeted immunotherapy and radioimmunotherapy by quantitative positron emission tomography (PET) imaging.
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Photoacoustic ocular imaging.
Opt Lett
PUBLISHED: 02-04-2010
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We developed a photoacoustic ocular imaging device and demonstrated its utility in imaging the deeper layers of the eye including the retina, choroid, and optic nerve. Using safe laser intensity, the photoacoustic system was able to visualize the blood distribution of an enucleated pigs eye and an eye of a living rabbit. Ultrasound images, which were simultaneously acquired, were overlaid on the photoacoustic images to visualize the eyes anatomy. Such a system may be used in the future for early detection and improved management of neovascular ocular diseases, including wet age-related macular degeneration and proliferative diabetic retinopathy.
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Evaluation of a (64)Cu-labeled cystine-knot peptide based on agouti-related protein for PET of tumors expressing alphavbeta3 integrin.
J. Nucl. Med.
PUBLISHED: 02-04-2010
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Recently, a truncated form of the agouti-related protein (AgRP), a 4-kDa cystine-knot peptide of human origin, was used as a scaffold to engineer mutants that bound to alpha(v)beta(3) integrin with high affinity and specificity. In this study, we evaluated the potential of engineered integrin-binding AgRP peptides for use as cancer imaging agents in living subjects.
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An engineered knottin peptide labeled with 18F for PET imaging of integrin expression.
Bioconjug. Chem.
PUBLISHED: 11-14-2009
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Knottins are small constrained polypeptides that share a common disulfide-bonded framework and a triple-stranded beta-sheet fold. Previously, directed evolution of the Ecballium elaterium trypsin inhibitor (EETI-II) knottin led to the identification of a mutant that bound to tumor-specific alpha(v)beta(3) and alpha(v)beta(5) integrin receptors with low nanomolar affinity. The objective of this study was to prepare and evaluate a radiofluorinated version of this knottin (termed 2.5D) for microPET imaging of integrin positive tumors in living subjects. Knottin peptide 2.5D was prepared by solid-phase synthesis and folded in vitro, and its free N-terminal amine was reacted with N-succinimidyl-4-18/19F-fluorobenzoate (18/19F-SFB) to produce the fluorinated peptide 18/19F-FB-2.5D. The binding affinities of unlabeled knottin peptide 2.5D and 19F-FB-2.5D to U87MG glioblastoma cells were measured by competition binding assay using 125I-labeled echistatin. It was found that unlabeled 2.5D and 19F-FB-2.5D competed with 125I-echistatin for binding to cell surface integrins with IC(50) values of 20.3 +/- 7.3 and 13.2 +/- 5.4 nM, respectively. Radiosynthesis of 18F-FB-2.5D resulted in a product with high specific activity (ca. 100 GBq/micromol). Next, biodistribution and positron emission tomography (PET) imaging studies were performed to evaluate the in vivo behavior of 18F-FB-2.5D. Approximately 3.7 MBq 18F-FB-2.5D was injected into U87MG tumor-bearing mice via the tail vein. Biodistribution studies demonstrated that 18F-FB-2.5D had moderate tumor uptake at 0.5 h post injection, and coinjection of a large excess of the unlabeled peptidomimetic c(RGDyK) as a blocking agent significantly reduced tumor uptake (1.90 +/- 1.15 vs 0.57 +/- 0.14%ID/g, 70% inhibition, P < 0.05). In vivo microPET imaging showed that 18F-FB-2.5D rapidly accumulated in the tumor and quickly cleared from the blood through the kidneys, allowing excellent tumor-to-normal tissue contrast to be obtained. Collectively, 18F-FB-2.5D allows integrin-specific PET imaging of U87MG tumors with good contrast and further demonstrates that knottins are excellent peptide scaffolds for development of PET probes with potential for clinical translation.
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Development and intra-institutional and inter-institutional validation of a comprehensive new hepatobiliary software: Part 1--Liver and gallbladder function.
Nucl Med Commun
PUBLISHED: 10-28-2009
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To develop a software tool for quantification of liver and gallbladder function, and to assess the repeatability and reproducibility of measurements made with it.
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BRET3: a red-shifted bioluminescence resonance energy transfer (BRET)-based integrated platform for imaging protein-protein interactions from single live cells and living animals.
FASEB J.
PUBLISHED: 04-07-2009
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Taking advantage of the bioluminescence resonance energy transfer (BRET) phenomenon, we report the development of a highly photon-efficient, self-illuminating fusion protein combining a mutant red fluorescent protein (mOrange) and a mutant Renilla reniformis luciferase (RLuc8). This new BRET fusion protein (BRET3) exhibits severalfold improvement in light intensity in comparison with existing BRET fusion proteins. BRET3 also exhibits the most red-shifted light output (564-nm peak wavelength) of any reported bioluminescent protein that utilizes its natural substrate coelenterazine, a benefit of which is demonstrated at various tissue depths in small animals. The imaging utility of BRET3 at the single-cell level is demonstrated using an intramolecular sensor incorporating two mammalian target of rapamycin pathway proteins (FKBP12 and FRB) that dimerize only in the presence of rapamycin. With its increased photon intensity, red-shifted light output, and good spectral resolution (approximately 85 nm), BRET3 shows improved spatial and temporal resolution for measuring intracellular events in single cells and in living small animal models. The development of further BRET3-based assays will allow imaging of protein-protein interactions using a single assay directly scalable from intact living cells to small living subjects, allowing accelerated drug discovery.
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A comparison between time domain and spectral imaging systems for imaging quantum dots in small living animals.
Mol Imaging Biol
PUBLISHED: 03-25-2009
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We quantified the performance of time-domain imaging (TDI) and spectral imaging (SI) for fluorescence imaging of quantum dots (QDs) in three distinct imaging instruments: eXplore Optix (TDI, Advanced Research Technologies Inc.), Maestro (SI, CRi Inc.), and IVIS-Spectrum (SI, Caliper Life Sciences Inc.).
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Stem cell-mediated accelerated bone healing observed with in vivo molecular and small animal imaging technologies in a model of skeletal injury.
J. Orthop. Res.
PUBLISHED: 03-18-2009
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Adult stem cells are promising therapeutic reagents for skeletal regeneration. We hope to validate by molecular imaging technologies the in vivo life cycle of adipose-derived multipotent cells (ADMCs) in an animal model of skeletal injury. Primary ADMCs were lentivirally transfected with a fusion reporter gene and injected intravenously into mice with bone injury or sham operation. Bioluminescence imaging (BLI), [(18)F]FHBG (9-(fluoro-hydroxy-methyl-butyl-guanine)-micro-PET, [(18)F]Fluoride ion micro-PET and micro-CT were performed to monitor stem cells and their effect. Bioluminescence microscopy and immunohistochemistry were done for histological confirmation. BLI showed ADMCs traffic from the lungs then to the injury site. BLI microscopy and immunohistochemistry confirmed the ADMCs in the bone defect. Micro-CT measurements showed increased bone healing in the cell-injected group compared to the noninjected group at postoperative day 7 (p < 0.05). Systemically administered ADMCs traffic to the site of skeletal injury and facilitate bone healing, as demonstrated by molecular and small animal imaging. Molecular imaging technologies can validate the usage of adult adipose tissue-derived multipotent cells to promote fracture healing. Imaging can in the future help establish therapeutic strategies including dosage and administration route.
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Novel strategy for a cocktail 18F-fluoride and 18F-FDG PET/CT scan for evaluation of malignancy: results of the pilot-phase study.
J. Nucl. Med.
PUBLISHED: 03-16-2009
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(18)F-FDG PET/CT is used for detecting cancer and monitoring cancer response to therapy. However, because of the variable rates of glucose metabolism, not all cancers are identified reliably. Sodium (18)F was previously used for bone imaging and can be used as a PET/CT skeletal tracer. The combined administration of (18)F and (18)F-FDG in a single PET/CT study for cancer detection has not been reported to date.
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64Cu-labeled affibody molecules for imaging of HER2 expressing tumors.
Mol Imaging Biol
PUBLISHED: 03-10-2009
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The development of molecular probes based on novel engineered protein constructs is under active investigation due to the great potential of this generalizable strategy for imaging a variety of tumor targets.
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Engineered knottin peptides: a new class of agents for imaging integrin expression in living subjects.
Cancer Res.
PUBLISHED: 03-10-2009
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There is a critical need for molecular imaging agents to detect cell surface integrin receptors that are present in human cancers. Previously, we used directed evolution to engineer knottin peptides that bind with high affinity ( approximately 10 to 30 nmol/L) to integrin receptors that are overexpressed on the surface of tumor cells and the tumor neovasculature. To evaluate these peptides as molecular imaging agents, we site-specifically conjugated Cy5.5 or (64)Cu-1,4,7,10-tetra-azacyclododecane-N,N,N,N-tetraacetic acid (DOTA) to their N termini, and used optical and positron emission tomography (PET) imaging to measure their uptake and biodistribution in U87MG glioblastoma murine xenograft models. NIR fluorescence and microPET imaging both showed that integrin binding affinity plays a strong role in the tumor uptake of knottin peptides. Tumor uptake at 1 hour postinjection for two high-affinity (IC(50), approximately 20 nmol/L) (64)Cu-DOTA-conjugated knottin peptides was 4.47% +/- 1.21% and 4.56% +/- 0.64% injected dose/gram (%ID/g), compared with a low-affinity knottin peptide (IC(50), approximately 0.4 mumol/L; 1.48 +/- 0.53%ID/g) and c(RGDyK) (IC(50), approximately 1 mumol/L; 2.32 +/- 0.55%ID/g), a low-affinity cyclic pentapeptide under clinical development. Furthermore, (64)Cu-DOTA-conjugated knottin peptides generated lower levels of nonspecific liver uptake ( approximately 2%ID/g) compared with c(RGDyK) ( approximately 4%ID/g) 1 hour postinjection. MicroPET imaging results were confirmed by in vivo biodistribution studies. (64)Cu-DOTA-conjugated knottin peptides were stable in mouse serum, and in vivo metabolite analysis showed minimal degradation in the blood or tumor upon injection. Thus, engineered integrin-binding knottin peptides show great potential as clinical diagnostics for a variety of cancers.
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Controlling the selection stringency of phage display using a microfluidic device.
Lab Chip
PUBLISHED: 03-03-2009
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We report the utilization of microfluidic technology to phage selection and demonstrate that accurate control of washing stringency in our microfluidic magnetic separator (MMS) directly impacts the diversity of isolated peptide sequences. Reproducible generation of magnetic and fluidic forces allows controlled washing conditions that enable rapid convergence of selected peptide sequences. These findings may provide a foundation for the development of automated microsystems for rapid in vitro directed evolution of affinity reagents.
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Combined 18F-fluoride and 18F-FDG PET/CT scanning for evaluation of malignancy: results of an international multicenter trial.
J. Nucl. Med.
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(18)F-FDG PET/CT is used in a variety of cancers, but because of variable rates of glucose metabolism, not all cancers are reliably identified. (18)F(-) PET/CT allows for the acquisition of highly sensitive and specific images of the skeleton. We prospectively evaluated combined (18)F(-)/(18)F-FDG as a single PET/CT examination for evaluation of cancer patients and compared it with separate (18)F(-) PET/CT and (18)F-FDG PET/CT scans.
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Improving image quality by accounting for changes in water temperature during a photoacoustic tomography scan.
PLoS ONE
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The emerging field of photoacoustic tomography is rapidly evolving with many new system designs and reconstruction algorithms being published. Many systems use water as a coupling medium between the scanned object and the ultrasound transducers. Prior to a scan, the water is heated to body temperature to enable small animal imaging. During the scan, the water heating system of some systems is switched off to minimize the risk of bubble formation, which leads to a gradual decrease in water temperature and hence the speed of sound. In this work, we use a commercially available scanner that follows this procedure, and show that a failure to model intra-scan temperature decreases as small as 1.5°C leads to image artifacts that may be difficult to distinguish from true structures, particularly in complex scenes. We then improve image quality by continuously monitoring the water temperature during the scan and applying variable speed of sound corrections in the image reconstruction algorithm. While upgrading to an air bubble-free heating pump and keeping it running during the scan could also solve the changing temperature problem, we show that a software correction for the temperature changes provides a cost-effective alternative to a hardware upgrade. The efficacy of the software corrections was shown to be consistent across objects of widely varying appearances, namely physical phantoms, ex vivo tissue, and in vivo mouse imaging. To the best of our knowledge, this is the first study to demonstrate the efficacy of modeling temporal variations in the speed of sound during photoacoustic scans, as opposed to spatial variations as focused on by previous studies. Since air bubbles pose a common problem in ultrasonic and photoacoustic imaging systems, our results will be useful to future small animal imaging studies that use scanners with similarly limited heating units.
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Unexpected dissemination patterns in lymphoma progression revealed by serial imaging within a murine lymph node.
Cancer Res.
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Non-Hodgkin lymphoma (NHL) is a heterogeneous and highly disseminated disease, but the mechanisms of its growth and dissemination are not well understood. Using a mouse model of this disease, we used multimodal imaging, including intravital microscopy (IVM) combined with bioluminescence, as a powerful tool to better elucidate NHL progression. We injected enhanced green fluorescent protein and luciferase-expressing E?-Myc/Arf(-/-) (Cdkn2a(-/-)) mouse lymphoma cells (EL-Arf(-/-)) into C57BL/6NCrl mice intravenously. Long-term observation inside a peripheral lymph node was enabled by a novel lymph node internal window chamber technique that allows chronic, sequential lymph node imaging under in vivo physiologic conditions. Interestingly, during early stages of tumor progression we found that few if any lymphoma cells homed initially to the inguinal lymph node (ILN), despite clear evidence of lymphoma cells in the bone marrow and spleen. Unexpectedly, we detected a reproducible efflux of lymphoma cells from spleen and bone marrow, concomitant with a massive and synchronous influx of lymphoma cells into the ILN, several days after injection. We confirmed a coordinated efflux/influx of tumor cells by injecting EL-Arf(-/-) lymphoma cells directly into the spleen and observing a burst of lymphoma cells, validating that the burst originated in organs remote from the lymph nodes. Our findings argue that in NHL an efflux of tumor cells from one disease site to another, distant site in which they become established occurs in discrete bursts.
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Endoscopic imaging of Cerenkov luminescence.
Biomed Opt Express
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We demonstrate feasibility of endoscopic imaging of Cerenkov light originated when charged nuclear particles, emitted from radionuclides, travel through a biological tissue of living subjects at superluminal velocity. The endoscopy imaging system consists of conventional optical fiber bundle/ clinical endoscopes, an optical imaging lens system, and a sensitive low-noise charge coupled device (CCD) camera. Our systematic studies using phantom samples show that Cerenkov light from as low as 1 µCi of radioactivity emitted from (18)F-Fluorodeoxyglucose (FDG) can be coupled and transmitted through conventional optical fibers and endoscopes. In vivo imaging experiments with tumor bearing mice, intravenously administered with (18)F-FDG, further demonstrated that Cerenkov luminescence endoscopy is a promising new tool in the field of endoscopic molecular imaging.
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A hybrid least squares and principal component analysis algorithm for Raman spectroscopy.
PLoS ONE
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Raman spectroscopy is a powerful technique for detecting and quantifying analytes in chemical mixtures. A critical part of Raman spectroscopy is the use of a computer algorithm to analyze the measured Raman spectra. The most commonly used algorithm is the classical least squares method, which is popular due to its speed and ease of implementation. However, it is sensitive to inaccuracies or variations in the reference spectra of the analytes (compounds of interest) and the background. Many algorithms, primarily multivariate calibration methods, have been proposed that increase robustness to such variations. In this study, we propose a novel method that improves robustness even further by explicitly modeling variations in both the background and analyte signals. More specifically, it extends the classical least squares model by allowing the declared reference spectra to vary in accordance with the principal components obtained from training sets of spectra measured in prior characterization experiments. The amount of variation allowed is constrained by the eigenvalues of this principal component analysis. We compare the novel algorithm to the least squares method with a low-order polynomial residual model, as well as a state-of-the-art hybrid linear analysis method. The latter is a multivariate calibration method designed specifically to improve robustness to background variability in cases where training spectra of the background, as well as the mean spectrum of the analyte, are available. We demonstrate the novel algorithms superior performance by comparing quantitative error metrics generated by each method. The experiments consider both simulated data and experimental data acquired from in vitro solutions of Raman-enhanced gold-silica nanoparticles.
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Shape matters: intravital microscopy reveals surprising geometrical dependence for nanoparticles in tumor models of extravasation.
Nano Lett.
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Delivery is one of the most critical obstacles confronting nanoparticle use in cancer diagnosis and therapy. For most oncological applications, nanoparticles must extravasate in order to reach tumor cells and perform their designated task. However, little understanding exists regarding the effect of nanoparticle shape on extravasation. Herein we use real-time intravital microscopic imaging to meticulously examine how two different nanoparticles behave across three different murine tumor models. The study quantitatively demonstrates that high-aspect ratio single-walled carbon nanotubes (SWNTs) display extravasational behavior surprisingly different from, and counterintuitive to, spherical nanoparticles although the nanoparticles have similar surface coatings, area, and charge. This work quantitatively indicates that nanoscale extravasational competence is highly dependent on nanoparticle geometry and is heterogeneous.
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Deep tissue photoacoustic imaging using a miniaturized 2-D capacitive micromachined ultrasonic transducer array.
IEEE Trans Biomed Eng
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In this paper, we demonstrate 3-D photoacoustic imaging (PAI) of light absorbing objects embedded as deep as 5 cm inside strong optically scattering phantoms using a miniaturized (4 mm × 4 mm × 500 ?m), 2-D capacitive micromachined ultrasonic transducer (CMUT) array of 16 × 16 elements with a center frequency of 5.5 MHz. Two-dimensional tomographic images and 3-D volumetric images of the objects placed at different depths are presented. In addition, we studied the sensitivity of CMUT-based PAI to the concentration of indocyanine green dye at 5 cm depth inside the phantom. Under optimized experimental conditions, the objects at 5 cm depth can be imaged with SNR of about 35 dB and a spatial resolution of approximately 500 ?m. Results demonstrate that CMUTs with integrated front-end amplifier circuits are an attractive choice for achieving relatively high depth sensitivity for PAI.
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Proof-of-concept study of monitoring cancer drug therapy with cerenkov luminescence imaging.
J. Nucl. Med.
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Cerenkov luminescence imaging (CLI) has emerged as a less expensive, easier-to-use, and higher-throughput alternative to other nuclear imaging modalities such as PET. It is expected that CLI will find many applications in biomedical research such as cancer detection, probe development, drug screening, and therapy monitoring. In this study, we explored the possibility of using CLI to monitor drug efficacy by comparisons against PET. To assess the performance of both modalities in therapy monitoring, 2 murine tumor models (large cell lung cancer cell line H460 and prostate cancer cell line PC3) were given bevacizumab versus vehicle treatments. Two common radiotracers, 3-deoxy-3-(18)F-fluorothymidine ((18)F-FLT) and (18)F-FDG, were used to monitor bevacizumab treatment efficacy.
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Positron emission tomography of 64Cu-DOTA-Rituximab in a transgenic mouse model expressing human CD20 for clinical translation to image NHL.
Mol Imaging Biol
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This study aims to evaluate (64)Cu-DOTA-rituximab (PETRIT) in a preclinical transgenic mouse model expressing human CD20 for potential clinical translation.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.