Induction of complementary immunogenic necroptosis and apoptosis cell death pathways inhibits cancer metastasis and relapse.

Interactions of light-sensitive drugs and materials with Cerenkov radiation-emitting radiopharmaceuticals generate cytotoxic reactive oxygen species (ROS) to inhibit localized and disseminated cancer progression, but the cell death mechanisms underlying this radionuclide stimulated dynamic therapy (RaST) remain elusive. Using ROS-regenerative nanophotosensitizers coated with a tumor-targeting transferrin-titanocene complex (TiO2-TC-Tf) and radiolabeled 2-fluorodeoxyglucose (18FDG), we found that adherent dying cells maintained metabolic activity with increased membrane permeabilization. Mechanistic assessment of these cells revealed that RaST activated the expression of RIPK-1 and RIPK-3, which mediate necroptosis cell death. Subsequent recruitment of the nuclear factors kappa B and the executioner mixed lineage kinase domain-like pseudo kinase (MLKL) triggered plasma membrane permeabilization and pore formation, respectively, followed by the release of cytokines and immunogenic damage-associated molecular patterns (DAMPs). In immune-deficient breast cancer models with adequate stroma and growth factors that recapitulate the human tumor microenvironment, RaST failed to inhibit tumor progression and the ensuing lung metastasis. A similar aggressive tumor model in immunocompetent mice responded to RaST, achieving a remarkable partial response (PR) and complete response (CR) with no evidence of lung metastasis, suggesting active immune system engagement. RaST recruited antitumor CD11b+, CD11c+, and CD8b+ effector immune cells after initiating dual immunogenic apoptosis and necroptosis cell death pathways in responding tumors in vivo. Over time, cancer cells upregulated the expression of negative immune regulating cytokine (TGF-ß) and soluble immune checkpoints (sICP) to challenge RaST effect in the CR mice. Using a signal-amplifying cancer-imaging agent, LS301, we identified latent minimal residual disseminated tumors in the lymph nodes (LNs) of the CR group. Despite increased protumor immunogens in the CR mice, RaST prevented cancer relapse and metastasis through dynamic redistribution of ROS-regenerative TiO2 from bones at the early treatment stage to the spleen and LNs, maintaining active immunity against cancer progression and migration. This study reveals the immune-mechanistic underpinnings of RaST-mediated antitumor immune response and highlights immunogenic reprogramming of tumors in response to RaST. Overcoming apoptosis resistance through complementary necroptosis activation paves the way for strategic drug combinations to improve cancer treatment.

Development of New CD38 Targeted Peptides for Cancer Imaging.

PURPOSE: Multiple myeloma (MM) affects over 35,000 patients each year in the US. There remains a need for versatile Positron Emission Tomography (PET) tracers for the detection, accurate staging, and monitoring of treatment response of MM that have optimal specificity and translational attributes. CD38 is uniformly overexpressed in MM and thus represents an ideal target to develop CD38-targeted small molecule PET radiopharmaceuticals to address these challenges. PROCEDURES: Using phage display peptide libraries and pioneering algorithms, we identified novel CD38 specific peptides. Imaging bioconjugates were synthesized using solid phase peptide chemistry, and systematically analyzed in vitro and in vivo in relevant MM systems. RESULTS: The CD38-targeted bioconjugates were radiolabeled with copper-64 (64Cu) with100% radiochemical purity and an average specific activity of 3.3 - 6.6 MBq/nmol. The analog NODAGA-PEG4-SL022-GGS (SL022: Thr-His-Tyr-Pro-Ile-Val-Ile) had a Kd of 7.55 ± 0.291 nM and was chosen as the lead candidate. 64Cu-NODAGA-PEG4-SL022-GGS demonstrated high binding affinity to CD38 expressing human myeloma MM.1S-CBR-GFP-WT cells, which was blocked by the non-radiolabeled version of the peptide analog and anti-CD38 clinical antibodies, daratumumab and isatuximab, by 58%, 73%, and 78%, respectively. The CD38 positive MM.1S-CBR-GFP-WT cells had > 68% enhanced cellular binding when compared to MM.1S-CBR-GFP-KO cells devoid of CD38. Furthermore, our new CD38-targeted radiopharmaceutical allowed visualization of tumors located in marrow rich bones, remaining there for up to 4 h. Clearance from non-target organs occurred within 60 min. Quantitative PET data from a murine disseminated tumor model showed significantly higher accumulation in the bones of tumor-bearing animals compared to tumor-naïve animals (SUVmax 2.06 ± 0.4 versus 1.24 ± 0.4, P = 0.02). Independently, tumor uptake of the target compound was significantly higher (P = 0.003) compared to the scrambled peptide, 64Cu-NODAGA-PEG4-SL041-GGS (SL041: Thr-Tyr-His-Ile-Pro-Ile-Val). The subcutaneous MM model demonstrated significantly higher accumulation in tumors compared to muscle at 1 and 4 h after tracer administration (SUVmax 0.8 ± 0.2 and 0.14 ± 0.04, P = 0.04 at 1 h; SUVmax 0.89 ± 0.01 and 0.09 ± 0.01, P = 0.0002 at 4 h). CONCLUSIONS: The novel CD38-targeted, radiolabeled bioconjugates were specific and allowed visualization of MM, providing a starting point for the clinical translation of such tracers for the detection of MM.

Side-chain modification of collagen-targeting peptide prevents dye aggregation for improved molecular imaging of arthritic joints.

Near-infrared (NIR) dye-peptide conjugates are widely used for tissue-targeted molecular fluorescence imaging of pathophysiologic conditions. However, the significant contribution of both dye and peptide to the net mass of these bioconjugates implies that small changes in either component could alter their photophysical and biological properties. Here, we synthesized and conjugated a type I collagen targeted peptide, RRANAALKAGELYKCILY, to either a hydrophobic (LS1000) or hydrophilic (LS1006) NIR fluorescent dye. Spectroscopic analysis revealed rapid self-assembly of both LS1000 and LS1006 in aqueous media to form stable dimeric/H aggregates, regardless of the free dye's solubility in water. We discovered that replacing the cysteine residue in LS1000 and LS1006 with acetamidomethyl cysteine to afford LS1001 and LS1107, respectively, disrupted the peptide's self-assembly and activated the previously quenched dye's fluorescence in aqueous conditions. These results highlight the dominant role of the octadecapeptide, but not the dye molecules, in controlling the photophysical properties of these conjugates by likely sequestering or extruding the hydrophobic or hydrophilic dyes, respectively. Application of the compounds for imaging collagen-rich tissue in an animal model of inflammatory arthritis showed enhanced uptake of all four conjugates, which retained high collagen-binding affinity, in inflamed joints. Moreover, LS1001 and LS1107 improved the arthritic joint-to-background contrast, suggesting that reduced aggregation enhanced the clearance of these compounds from non-target tissues. Our results highlight a peptide-driven strategy to alter the aggregation states of molecular probes in aqueous solutions, irrespective of the water-solubilizing properties of the dye molecules. The interplay between the monomeric and aggregated forms of the conjugates using simple thiol-modifiers lends the peptide-driven approach to diverse applications, including the effective imaging of inflammatory arthritis joints.

Nanoarchitectonics of g-C3N4 Nanosheets with a AuCu Enhancement Effect for Superior Photo- and Electrochemical Activity.

AuCu alloy nanoparticles (NPs) were embedded in superior thin g-C3N4 nanosheets by a mechanochemical pre-reaction and subsequent thermal polymerization at high temperature. The introduction of AuCu NPs increased conductivity, decreased the band gap, expended light absorption, and improved the separation and transfer efficiencies of photogenerated electrons and holes. Moreover, the uniform distribution of AuCu NPs in g-C3N4 nanosheets is ascribed to the pre-reaction of bulk g-C3N4 and metal salts to create activity cites. The adsorption ability in the visible light region was improved due to the plasma effect of Au. AuCu/g-C3N4 composites (AuCu/CN-1%) with optimized component ratios revealed the highest transient photocurrent responses, the lowest electrochemical impedance arc radius, and the best photocatalytic H2 evolution rate of 930.2 µmol g-1 h-1. These findings exhibited that loading AuCu bimetallic NPs could efficiently offset some disadvantages of g-C3N4 and improve its photocatalytic performances.

Orthogonal targeting of osteoclasts and myeloma cells for radionuclide stimulated dynamic therapy induces multidimensional cell death pathways.

Rationale: Multiple myeloma (MM) is a multifocal malignancy of bone marrow plasma cells, characterized by vicious cycles of remission and relapse that eventually culminate in death. The disease remains mostly incurable largely due to the complex interactions between the bone microenvironment (BME) and MM cells (MMC). In the "vicious cycle" of bone disease, abnormal activation of osteoclasts (OCs) by MMC causes severe osteolysis, promotes immune evasion, and stimulates the growth of MMC. Disrupting these cancer-stroma interactions would enhance treatment response. Methods: To disrupt this cycle, we orthogonally targeted nanomicelles (NM) loaded with non-therapeutic doses of a photosensitizer, titanocene (TC), to VLA-4 (α4ß1, CD49d/CD29) expressing MMC (MM1.S) and αvß3 (CD51/CD61) expressing OC. Concurrently, a non-lethal dose of a radiopharmaceutical, 18F-fluorodeoxyglucose ([18F]FDG) administered systemically interacted with TC (radionuclide stimulated therapy, RaST) to generate cytotoxic reactive oxygen species (ROS). The in vitro and in vivo effects of RaST were characterized in MM1.S cell line, as well as in xenograft and isograft MM animal models. Results: Our data revealed that RaST induced non-enzymatic hydroperoxidation of cellular lipids culminating in mitochondrial dysfunction, DNA fragmentation, and caspase-dependent apoptosis of MMC using VLA-4 avid TC-NMs. RaST upregulated the expression of BAX, Bcl-2, and p53, highlighting the induction of apoptosis via the BAK-independent pathway. The enhancement of multicopper oxidase enzyme F5 expression, which inhibits lipid hydroperoxidation and Fenton reaction, was not sufficient to overcome RaST-induced increase in the accumulation of irreversible function-perturbing α,ß-aldehydes that exerted significant and long-lasting damage to both DNA and proteins. In vivo, either VLA-4-TC-NM or αvß3-TC-NMs RaST induced a significant therapeutic effect on immunocompromised but not immunocompetent MM-bearing mouse models. Combined treatment with both VLA-4-TC-NM and αvß3-TC-NMs synergistically inhibited osteolysis, reduced tumor burden, and prevented rapid relapse in both in vivo models of MM. Conclusions: By targeting MM and bone cells simultaneously, combination RaST suppressed MM disease progression through a multi-prong action on the vicious cycle of bone cancer. Instead of using the standard multidrug approach, our work reveals a unique photophysical treatment paradigm that uses nontoxic doses of a single light-sensitive drug directed orthogonally to cancer and bone cells, followed by radionuclide-stimulated generation of ROS to inhibit tumor progression and minimize osteolysis in both immunocompetent murine and immunocompromised human MM models.

Ultrabright fluorescent nanoscale labels for the femtomolar detection of analytes with standard bioassays.

The detection and quantification of low-abundance molecular biomarkers in biological samples is challenging. Here, we show that a plasmonic nanoscale construct serving as an 'add-on' label for a broad range of bioassays improves their signal-to-noise ratio and dynamic range without altering their workflow and readout devices. The plasmonic construct consists of a bovine serum albumin scaffold with approximately 210 IRDye 800CW fluorophores (with a fluorescence intensity approximately 6,700-fold that of a single 800CW fluorophore), a polymer-coated gold nanorod acting as a plasmonic antenna and biotin as a high-affinity biorecognition element. Its emission wavelength can be tuned over the visible and near-infrared spectral regions by modifying its size, shape and composition. It improves the limit of detection in fluorescence-linked immunosorbent assays by up to 4,750-fold and is compatible with multiplexed bead-based immunoassays, immunomicroarrays, flow cytometry and immunocytochemistry methods, and it shortens overall assay times (to 20 min) and lowers sample volumes, as shown for the detection of a pro-inflammatory cytokine in mouse interstitial fluid and of urinary biomarkers in patient samples.

Selective imaging of solid tumours via the calcium-dependent high-affinity binding of a cyclic octapeptide to phosphorylated Annexin A2.

The heterogeneity and continuous genetic adaptation of tumours complicate their detection and treatment via the targeting of genetic mutations. However, hallmarks of cancer such as aberrant protein phosphorylation and calcium-mediated cell signalling provide broadly conserved molecular targets. Here, we show that, for a range of solid tumours, a cyclic octapeptide labelled with a near-infrared dye selectively binds to phosphorylated Annexin A2 (pANXA2), with high affinity at high levels of calcium. Because of cancer-cell-induced pANXA2 expression in tumour-associated stromal cells, the octapeptide preferentially binds to the invasive edges of tumours and then traffics within macrophages to the tumour's necrotic core. As proof-of-concept applications, we used the octapeptide to detect tumour xenografts and metastatic lesions, and to perform fluorescence-guided surgical tumour resection, in mice. Our findings suggest that high levels of pANXA2 in association with elevated calcium are present in the microenvironment of most solid cancers. The octapeptide might be broadly useful for selective tumour imaging and for delivering drugs to the edges and to the core of solid tumours.

Electrospray Functionalization of Titanium Dioxide Nanoparticles with Transferrin for Cerenkov Radiation Induced Cancer Therapy.

Titanium dioxide (TiO2) nanoparticles have shown success as photosensitizers in the form of light-based cancer therapy called Cerenkov radiation induced therapy (CRIT). While TiO2 nanoparticles have been reported to be an effective therapeutic agent, there has been little work to control their functionalization and stability in aqueous suspension. In this work, the controlled coating of 25 nm diameter TiO2 nanoparticles with the glycoprotein transferrin (Tf) for application in CRIT was demonstrated using an electrospray system. Monodisperse nanoscale droplets containing TiO2 and Tf were dried during flight, coating the proteins on the surface of the metal oxide nanoparticles. Real-time scanning mobility particle sizing, dynamic light scattering, and transmission electron microscopy show efficient control of the Tf coating thickness when varying the droplet size and the ratio of Tf to TiO2 in the electrospray precursor suspension. Further, the functionality of Tf-coated TiO2 nanoparticles was demonstrated, and these particles were found to have enhanced targeting activity of Tf to the Tf receptor after electrospray processing. The electrospray-coated Tf/TiO2 particles were also found to be more effective at killing the multiple myeloma cell line MM1.S than that of nanoparticles prepared by other reported functionalization methods. In summary, this investigation not only provides a single-step functionalization technique for nanomaterials used in Cerenkov radiation induced therapy but also elucidates an electrospray coating technique for nanomaterials that can be used for a wide range of drug design and delivery purposes.

Dural lymphatics regulate clearance of extracellular tau from the CNS.

BACKGROUND: Alzheimer's disease is characterized by two main neuropathological hallmarks: extracellular plaques of amyloid-ß (Aß) protein and intracellular aggregates of tau protein. Although tau is normally a soluble monomer that bind microtubules, in disease it forms insoluble, hyperphosphorylated aggregates in the cell body. Aside from its role in AD, tau is also involved in several other neurodegenerative disorders collectively called tauopathies, such as progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), some forms of frontotemporal dementia, and argyrophilic grain disease (AGD). The prion hypothesis suggests that after an initial trigger event, misfolded forms of tau are released into the extracellular space, where they spread through different brain regions, enter cells, and seeding previously normal forms. Thus understanding mechanisms regulating the clearance of extracellular tau from the CNS is important. The discovery of a true lymphatic system in the dura and its potential role in mediating Aß pathology prompted us to investigate its role in regulating extracellular tau clearance. METHODS: To study clearance of extracellular tau from the brain, we conjugated monomeric human tau with a near-infrared dye cypate, and injected this labeled tau in the parenchyma of both wild-type and K14-VEGFR3-Ig transgenic mice, which lack a functional CNS lymphatic system. Following injection we performed longitudinal imaging using fluorescence molecular tomography (FMT) and quantified fluorescence to calculate clearance of tau from the brain. To complement this, we also measured tau clearance to the periphery by measuring plasma tau in both groups of mice. RESULTS: Our results show that a significantly higher amount of tau is retained in the brains of K14-VEGFR3-Ig vs. wild type mice at 48 and 72 h post-injection and its subsequent clearance to the periphery is delayed. We found that clearance of reference tracer human serum albumin (HSA) was also significantly delayed in the K14-VEGFR3-Ig mice. CONCLUSIONS: The dural lymphatic system appears to play an important role in clearance of extracellular tau, since tau clearance is impaired in the absence of functional lymphatics. Based on our baseline characterization of extracellular tau clearance, future studies are warranted to look at the interaction between tau pathology and efficiency of lymphatic function.

Utilizing the Multiradionuclide Resolving Power of SPECT and Dual Radiolabeled Single Molecules to Assess Treatment Response of Tumors.

PURPOSE: Single photon emission computed tomography (SPECT) radionuclide pairs having distinct decay rates and different energy maxima enable simultaneous detection of dual gamma signals and real-time assessment of dynamic functional and molecular processes in vivo. Here, we report image acquisition and quantification protocols for a single molecule labeled with two different radionuclides for functional SPECT imaging. PROCEDURES: LS370 and LS734 were prepared using modular solid phase peptide synthesis. Each agent has a caspase-3 cleavable reporting motif, flanked by a tyrosine residue and a chelator at the opposite end of molecule. Cell uptake and efflux were assessed in human MDA-MB-231 breast cancer cells. Biodistribution studies were conducted in tumor naive and orthotopic 4T1 metastatic breast cancer tumor mice. NanoSPECT dual-imaging validation and attenuation correction parameters were developed using phantom vials containing varying radionuclide concentrations. Proof-of-principle SPECT imaging was performed in MMTV-PyMT transgenic mice. RESULTS: LS370 and LS734 were singly or dually radiolabeled with (125)I and (111)In or (99m)Tc. Cell assays demonstrated 11-fold higher percent uptake (P < 0.001) of [(125)I]LS734 (3.6 ± 0.5) compared to [(125)I]LS370 (0.3 ± 0.3) at 2 h. Following chemotherapy, cellular retention of [(125)I]LS734 was 3-fold higher (P < 0.05) than untreated cells. Pharmacokinetics at 1 h postinjection demonstrated longer blood retention (%ID/g) for [(125)I]LS734 (3.2 ± 0.9) compared to [(125)I]LS370 (1.6 ± 0.1). In mice bearing bilateral orthotopic 4T1 tumors, the uptake (%ID/g) was 2.4 ± 0.3 for [(125)I]LS734 and 1.2 ± 0.03 for [(125)I]LS370. The iodinated tyrosine peptide residue label was stable under in vitro conditions for up to 24 h; rapid systemic deiodination (high thyroid uptake) was observed in vivo. Phantom studies using standards demonstrated deconvolution of radionuclide signals based on different gamma ray energies. In MMTV-PyMT mice imaged with dual-labeled [(111)In]-[(125)I]LS734, the gamma signals were separable and quantifiable. CONCLUSIONS: Image processing protocols were developed for quantitative signal separation resulting from a caspase-3 responsive dual-radiolabeled SPECT probe. Crosstalk unmixing was obtained for multiradionuclide NanoSPECT imaging. In vitro and in vivo data demonstrated structure-activity relationships for developing functional agents for ratiometric SPECT imaging.

Tunable ultrasmall visible-to-extended near-infrared emitting silver sulfide quantum dots for integrin-targeted cancer imaging.

The large size of many near-infrared (NIR) fluorescent nanoparticles prevents rapid extravasation from blood vessels and subsequent diffusion to tumors. This confines in vivo uptake to the peritumoral space and results in high liver retention. In this study, we developed a viscosity modulated approach to synthesize ultrasmall silver sulfide quantum dots (QDs) with distinct tunable light emission from 500 to 1200 nm and a QD core diameter between 1.5 and 9 nm. Conjugation of a tumor-avid cyclic pentapeptide (Arg-Gly-Asp-DPhe-Lys) resulted in monodisperse, water-soluble QDs (hydrodynamic diameter < 10 nm) without loss of the peptide's high binding affinity to tumor-associated integrins (KI = 1.8 nM/peptide). Fluorescence and electron microscopy showed that selective integrin-mediated internalization was observed only in cancer cells treated with the peptide-labeled QDs, demonstrating that the unlabeled hydrophilic nanoparticles exhibit characteristics of negatively charged fluorescent dye molecules, which typically do not internalize in cells. The biodistribution profiles of intravenously administered QDs in different mouse models of cancer reveal an exceptionally high tumor-to-liver uptake ratio, suggesting that the small sized QDs evaded conventional opsonization and subsequent high uptake in the liver and spleen. The seamless tunability of the QDs over a wide spectral range with only a small increase in size, as well as the ease of labeling the bright and noncytotoxic QDs with biomolecules, provides a platform for multiplexing information, tracking the trafficking of single molecules in cells, and selectively targeting disease biomarkers in living organisms without premature QD opsonization in circulating blood.

Dual-radiolabeled nanoparticle SPECT probes for bioimaging.

A gold nanoparticle was radiolabeled with (125)I and (111)In and functionalized with an MMP9-cleavable peptide to form a multispectral SPECT imaging contrast agent. Peptide cleavage from the nanoprobe by MMP9 was observed in vitro, and distinct pharmacokinetic properties of the contrast agent were observed between tumors with high or low MMP9 expression.

Ultrashort pulsed laser treatment inactivates viruses by inhibiting viral replication and transcription in the host nucleus.

Ultrashort pulsed laser irradiation is a new method for virus reduction in pharmaceuticals and blood products. Current evidence suggests that ultrashort pulsed laser irradiation inactivates viruses through an impulsive stimulated Raman scattering process, resulting in aggregation of viral capsid proteins. However, the specific functional defect(s) in viruses inactivated in this manner have not been demonstrated. This information is critical for the optimization and the extension of this treatment platform to other applications. Toward this goal, we investigated whether viral internalization, replication, or gene expression in cells were altered by ultrashort pulsed laser irradiation. Murine Cytomegalovirus (MCMV), an enveloped DNA virus, was used as a model virus. Using electron and fluorescence microscopy, we found that laser-treated MCMV virions successfully internalized in cells, as evidenced by the detection of intracellular virions, which was confirmed by the detection of intracellular viral DNA via PCR. Although the viral DNA itself remained polymerase-amplifiable after laser treatment, no viral replication or gene expression was observed in cells infected with laser-treated virus. These results, along with evidence from previous studies, support a model whereby the laser treatment stabilizes the capsid, which inhibits capsid uncoating within cells. By targeting the mechanical properties of viral capsids, ultrashort pulsed laser treatment represents a unique potential strategy to overcome viral mutational escape, with implications for combatting emerging or drug-resistant pathogens.

Evaluation of a triple-helical peptide with quenched FluorSophores for optical imaging of MMP-2 and MMP-9 proteolytic activity.

Matrix metalloproteinases (MMP) 2 and 9, the gelatinases, have consistently been associated with tumor progression. The development of gelatinase-specific probes will be critical for identifying in vivo gelatinoic activity to understand the molecular role of the gelatinases in tumor development. Recently, a self-assembling homotrimeric triple-helical peptide (THP), incorporating a sequence from type V collagen, with high substrate specificity to the gelatinases has been developed. To determine whether this THP would be suitable for imaging protease activity, 5-carboxyfluorescein (5FAM) was conjugated, resulting in 5FAM3-THP and 5FAM6-THP, which were quenched up to 50%. 5FAM6-THP hydrolysis by MMP-2 and MMP-9 displayed kcat/KM values of 1.5 × 104 and 5.4 × 103 M-1 s-1, respectively. Additionally 5FAM6-THP visualized gelatinase activity in gelatinase positive HT-1080 cells, but not in gelatinase negative MCF-7 cells. Furthermore, the fluorescence in the HT-1080 cells was greatly attenuated by the addition of a MMP-2 and MMP-9 inhibitor, SB-3CT, indicating that the observed fluorescence release was mediated by gelatinase proteolysis and not non-specific proteolysis of the THPs. These results demonstrate that THPs fully substituted with fluorophores maintain their substrate specificity to the gelatinases in human cancer cells and may be useful in in vivo molecular imaging of gelatinase activity.

Synthesis of dye conjugates to visualize the cancer cells using fluorescence microscopy.

The clinical diagnosis of most cancers is based on evaluation of histology microscopic slides to view the size and shape of cellular nuclei and morphological structure of tissue. To achieve this goal for in vivo and in-deep tissues, near infrared dyes-bovine serum albumin and immunoglobulin G conjugates were synthesized. The spectral study shows that the absorption and fluorescence of the dye conjugates are in the "tissue optical window" spectral ranges between 650 and 900 nm. The internalization and pinocytosis of the synthesized compounds were investigated at cell level using fluorescence microscopy to obtain the optimal concentration and staining time.

Tryptophan as the fingerprint for distinguishing aggressiveness among breast cancer cell lines using native fluorescence spectroscopy.

Tryptophan is investigated as the key native marker in cells to determine the level of metastasis competence in breast cell lines using native fluorescence spectroscopy. The ratio of fluorescence intensity at 340 nm to intensity at 460 nm is associated with aggressiveness of the cancer cells. We found that the fluorescence of aggressive breast cancer cell has a much higher contribution from tryptophan compared with that from the normal cells and nonaggressive breast cancer cell.

Probing distance-dependent plasmon-enhanced near-infrared fluorescence using polyelectrolyte multilayers as dielectric spacers.

Owing to their applications in biodetection and molecular bioimaging, near-infrared (NIR) fluorescent dyes are being extensively investigated. Most of the existing NIR dyes exhibit poor quantum yield, which hinders their translation to preclinical and clinical settings. Plasmonic nanostructures are known to act as tiny antennae for efficiently focusing the electromagnetic field into nanoscale volumes. The fluorescence emission from NIR dyes can be enhanced by more than thousand times by precisely placing them in proximity to gold nanorods. We have employed polyelectrolyte multilayers fabricated using layer-by-layer assembly as dielectric spacers for precisely tuning the distance between gold nanorods and NIR dyes. The aspect ratio of the gold nanorods was tuned to match the longitudinal localized surface plasmon resonance wavelength with the absorption maximum of the NIR dye to maximize the plasmonically enhanced fluorescence. The design criteria derived from this study lays the groundwork for ultrabright fluorescence bullets for in vitro and in vivo molecular bioimaging.

Native fluorescence spectroscopy reveals spectral differences among prostate cancer cell lines with different risk levels.

The spectral changes of native fluorophores among normal fibroblasts and cancer cell lines of different metastatic ability are investigated by fluorescence spectroscopy. The normal (fibroblast), moderately metastatic (DU-145), and advanced metastatic (PC-3) cell lines were each selectively excited at 300 nm, and their fluorescence emission spectra are analyzed using principal component analysis to explore the differences of the relative contents of tryptophan and reduced nicotinamide adenine dinucleotide in these cell lines. The results show that the tryptophan emission featured predominantly in the fluorescence spectra of the advanced metastatic cancer cells in comparison with the moderately metastatic cancer and normal cells.

Increased fluoroscopy time for central venous catheter placement by radiology residents versus staff radiologists.

PURPOSE: To evaluate differences in interventional radiology procedural fluoroscopy time (FT) for radiology residents versus staff radiologists, using central venous catheter (CVC) placement as an index service. METHODS: To minimize interservice and complexity variables, stand-alone temporary internal jugular CVC procedures were targeted for analysis. Reports and images from 1,067 temporary CVC services from 2 hospitals over 2 years were reviewed as part of a quality improvement initiative. Insertion site, catheter type (eg, smaller triple lumen versus larger hemodialysis), resident identifier, staff identifier, and documented FT were compiled and analyzed. RESULTS: Applying clinical (eg, concomitant venous angioplasty) and anatomic (eg, femoral access) exclusions, 537 cases with complete CVC procedure records were available for analysis. Radiology residents and staff radiologists were primary operators in 128 and 409 procedures, respectively. Distribution of resident procedures (82% right, 66% large lumen) was similar to that of staff (79% right, 63% large lumen). Mean FT of resident services was twice as long as that of staff services (1.24 minutes versus 0.63 minutes, P < .0001). Resident FT was independent of supervising staff radiologist. Increasing years of training for residents did not significantly reduce FT. CONCLUSIONS: When CVCs are placed by radiology residents, FT is double that for identical procedures performed by staff radiologists. Similar discrepancies likely exist for other interventional radiologic procedures. Residency training programs should initiate measures to monitor and manage fluoroscopy during interventional procedures to minimize radiation dose to patients, trainees, and other staff.

Central venous access: evolving roles of radiology and other specialties nationally over two decades.

PURPOSE: The aim of this study was to evaluate national trends in central venous access (CVA) procedures over 2 decades with regard to changing specialty group roles and places of service. METHODS: Aggregated claims data for temporary central venous catheter and long-term CVA device (CVAD) procedures were extracted from Medicare Physician/Supplier Procedure Summary Master Files from 1992 through 2011. Central venous catheter and CVAD procedure volumes by specialty group and place of service were studied. RESULTS: Between 1992 and 2011, temporary and long-term CVA placement procedures increased from 638,703 to 808,071 (+27%) and from 76,444 to 316,042 (+313%), respectively. For temporary central venous catheters, radiology (from 0.4% in 1992 to 32.6% in 2011) now exceeds anesthesiology (from 37% to 22%) and surgery (from 30.4% to 11.7%) as the dominant provider group. Surgery continues to dominate in placement and explantation of long-term CVADs (from 80.7% to 50.4% and from 81.6% to 47.7%, respectively), but radiology's share has grown enormously (from 0.7% to 37.6% and from 0.2% to 28.6%). Although volumes remain small (<10% of all procedures), midlevel practitioners have experienced >100-fold growth for most services. The inpatient hospital remains the dominant site for temporary CVA procedures (90.0% in 1992 and 81.2% in 2011), but the placement of long-term CVADs has shifted from the inpatient (from 68.9% to 45.2%) to hospital outpatient (from 26.9% to 44.3%) setting. In all hospital settings combined, radiologists place approximately half of all tunneled catheters and three-quarters all peripherally inserted central catheters. CONCLUSIONS: Over the past 2 decades, CVA procedures on Medicare beneficiaries have increased considerably. Radiology is now the dominant overall provider.