Ammonium-adduct chemical ionization to investigate anthropogenic oxygenated gas-phase organic compounds in urban air.

Volatile chemical products (VCPs) and other non-combustion-related sources have become important for urban air quality, and bottom-up calculations report emissions of a variety of functionalized compounds that remain understudied and uncertain in emissions estimates. Using a new instrumental configuration, we present online measurements of oxygenated organic compounds in a U.S. megacity over a 10-day wintertime sampling period, when biogenic sources and photochemistry were less active. Measurements were conducted at a rooftop observatory in upper Manhattan, New York City, USA using a Vocus chemical ionization time-of-flight mass spectrometer with ammonium (NH4 +) as the reagent ion operating at 1 Hz. The range of observations spanned volatile, intermediate-volatility, and semi-volatile organic compounds with targeted analyses of ~150 ions whose likely assignments included a range of functionalized compound classes such as glycols, glycol ethers, acetates, acids, alcohols, acrylates, esters, ethanolamines, and ketones that are found in various consumer, commercial, and industrial products. Their concentrations varied as a function of wind direction with enhancements over the highly-populated areas of the Bronx, Manhattan, and parts of New Jersey, and included abundant concentrations of acetates, acrylates, ethylene glycol, and other commonly-used oxygenated compounds. The results provide top-down constraints on wintertime emissions of these oxygenated/functionalized compounds with ratios to common anthropogenic marker compounds, and comparisons of their relative abundances to two regionally-resolved emissions inventories used in urban air quality models.

DNA-enabled rational design of fluorescence-Raman bimodal nanoprobes for cancer imaging and therapy.

Recently, surface-enhanced Raman scattering nanoprobes have shown tremendous potential in oncological imaging owing to the high sensitivity and specificity of their fingerprint-like spectra. As current Raman scanners rely on a slow, point-by-point spectrum acquisition, there is an unmet need for faster imaging to cover a clinically relevant area in real-time. Herein, we report the rational design and optimization of fluorescence-Raman bimodal nanoparticles (FRNPs) that synergistically combine the specificity of Raman spectroscopy with the versatility and speed of fluorescence imaging. DNA-enabled molecular engineering allows the rational design of FRNPs with a detection limit as low as 5 × 10-15 M. FRNPs selectively accumulate in tumor tissue mouse cancer models and enable real-time fluorescence imaging for tumor detection, resection, and subsequent Raman-based verification of clean margins. Furthermore, FRNPs enable highly efficient image-guided photothermal ablation of tumors, widening the scope of the NPs into the therapeutic realm.

Detection of Premalignant Gastrointestinal Lesions Using Surface-Enhanced Resonance Raman Scattering-Nanoparticle Endoscopy.

Cancers of the gastrointestinal (GI) tract are among the most frequent and most lethal cancers worldwide. An important reason for this high mortality is that early disease is typically asymptomatic, and patients often present with advanced, incurable disease. Even in high-risk patients who routinely undergo endoscopic screening, lesions can be missed due to their small size or subtle appearance. Thus, current imaging approaches lack the sensitivity and specificity to accurately detect incipient GI tract cancers. Here we report our finding that a single dose of a high-sensitivity surface-enhanced resonance Raman scattering nanoparticle (SERRS-NP) enables reliable detection of precancerous GI lesions in animal models that closely mimic disease development in humans. Some of these animal models have not been used previously to evaluate imaging probes for early cancer detection. The studies were performed using a commercial Raman imaging system, a newly developed mouse Raman endoscope, and finally a clinically applicable Raman endoscope for larger animal studies. We show that this SERRS-NP-based approach enables robust detection of small, premalignant lesions in animal models that faithfully recapitulate human esophageal, gastric, and colorectal tumorigenesis. This method holds promise for much earlier detection of GI cancers than currently possible and could lead therefore to marked reduction of morbidity and mortality of these tumor types.

Blockade of surface-bound TGF-ß on regulatory T cells abrogates suppression of effector T cell function in the tumor microenvironment.

Regulatory T cells (Tregs) suppress antitumor immunity by inhibiting the killing of tumor cells by antigen-specific CD8+ T cells. To better understand the mechanisms involved, we used ex vivo three-dimensional collagen-fibrin gel cultures of dissociated B16 melanoma tumors. This system recapitulated the in vivo suppression of antimelanoma immunity, rendering the dissociated tumor cells resistant to killing by cocultured activated, antigen-specific T cells. Immunosuppression was not observed when tumors excised from Treg-depleted mice were cultured in this system. Experiments with neutralizing antibodies showed that blocking transforming growth factor-ß (TGF-ß) also prevented immunosuppression. Immunosuppression depended on cell-cell contact or cellular proximity because soluble factors from the collagen-fibrin gel cultures did not inhibit tumor cell killing by T cells. Moreover, intravital, two-photon microscopy showed that tumor-specific Pmel-1 effector T cells physically interacted with tumor-resident Tregs in mice. Tregs isolated from B16 tumors alone were sufficient to suppress CD8+ T cell-mediated killing, which depended on surface-bound TGF-ß on the Tregs Immunosuppression of CD8+ T cells correlated with a decrease in the abundance of the cytolytic protein granzyme B and an increase in the cell surface amount of the immune checkpoint receptor programmed cell death protein 1 (PD-1). These findings suggest that contact between Tregs and antitumor T cells in the tumor microenvironment inhibits antimelanoma immunity in a TGF-ß-dependent manner and highlight potential ways to inhibit intratumoral Tregs therapeutically.

Confocal microscopy with strip mosaicing for rapid imaging over large areas of excised tissue.

Confocal mosaicing microscopy is a developing technology platform for imaging tumor margins directly in freshly excised tissue, without the processing required for conventional pathology. Previously, mosaicing on 12-×-12 mm² of excised skin tissue from Mohs surgery and detection of basal cell carcinoma margins was demonstrated in 9 min. Last year, we reported the feasibility of a faster approach called "strip mosaicing," which was demonstrated on a 10-×-10 mm² of tissue in 3 min. Here we describe further advances in instrumentation, software, and speed. A mechanism was also developed to flatten tissue in order to enable consistent and repeatable acquisition of images over large areas. We demonstrate mosaicing on 10-×-10 mm² of skin tissue with 1-µm lateral resolution in 90 s. A 2.5-×-3.5 cm² piece of breast tissue was scanned with 0.8-µm lateral resolution in 13 min. Rapid mosaicing of confocal images on large areas of fresh tissue potentially offers a means to perform pathology at the bedside. Imaging of tumor margins with strip mosaicing confocal microscopy may serve as an adjunct to conventional (frozen or fixed) pathology for guiding surgery.

Detection of intra-tumor self antigen recognition during melanoma tumor progression in mice using advanced multimode confocal/two photon microscope.

Determining how tumor immunity is regulated requires understanding the extent to which the anti-tumor immune response "functions" in vivo without therapeutic intervention. To better understand this question, we developed advanced multimodal reflectance confocal/two photon fluorescence intra-vital imaging techniques to use in combination with traditional ex vivo analysis of tumor specific T cells. By transferring small numbers of melanoma-specific CD8+ T cells (Pmel-1), in an attempt to mimic physiologic conditions, we found that B16 tumor growth alone was sufficient to induce naive Pmel-1 T cell proliferation and acquisition of effector phenotype. Tumor -primed Pmel-1 T cells, are capable of killing target cells in the periphery and secrete IFNγ, but are unable to mediate tumor regression. Within the tumor, Pmel-1 T cells have highly confined mobility, displaying long term interactions with tumor cells. In contrast, adoptively transferred non tumor-specific OT-I T cells show neither confined mobility, nor long term interaction with B16 tumor cells, suggesting that intra-tumor recognition of cognate self antigen by Pmel-1 T cells occurs during tumor growth. Together, these data indicate that lack of anti-tumor efficacy is not solely due to ignorance of self antigen in the tumor microenvironment but rather to active immunosuppressive influences preventing a protective immune response.

Rapid confocal imaging of large areas of excised tissue with strip mosaicing.

Imaging large areas of tissue rapidly and with high resolution may enable rapid pathology at the bedside. The limited field of view of high-resolution microscopes requires the merging of multiple images that are taken sequentially to cover a large area. This merging or mosaicing of images requires long acquisition and processing times, and produces artifacts. To reduce both time and artifacts, we developed a mosaicing method on a confocal microscope that images morphology in large areas of excised tissue with sub-cellular detail. By acquiring image strips with aspect ratios of 10:1 and higher (instead of the standard ~1:1) and "stitching" them in software, our method images 10 × 10 mm(2) area of tissue in about 3 min. This method, which we call "strip mosaicing," is currently three times as fast as our previous method.

In vivo microcartography and subcellular imaging of tumor angiogenesis: a novel platform for translational angiogenesis research.

PURPOSE: To eliminate the variable of tumor heterogeneity from a novel in vivo model of tumor angiogenesis. EXPERIMENTAL DESIGN: We developed a method to navigate tumor neovasculature in a living tissue microenvironment, enabling relocation of a cell- or microregion-of-interest, for serial in vivo imaging. Orthotopic melanoma was grown, in immunocompetent Tie2GFP mice. Intravital multiphoton fluorescence and confocal reflectance imaging was performed, on a custom microscope with motorized stage and coordinate navigation software. A point within a Tie2GFP+ microvessel was selected for relocation. Custom software predicted target coordinates based upon reference points (tissue-embedded polystyrene beads) and baseline target coordinates. Mice were removed from the stage to make previously-obtained target coordinates invalid in subsequent imaging. RESULTS: Coordinate predictions always relocated target points, in vivo, to within 10-200 microm (within a single 40x field-of-view). The model system provided a virtual living histology of tumor neovascularization and microenvironment, with subcellular spatial resolution and hemodynamic information. CONCLUSIONS: The navigation procedure, termed in vivo microcartography, permits control of tissue heterogeneity, as a variable. Tie2 may be the best reporter gene identified, to-date, for intravital microscopy of tumor angiogenesis. This novel model system should strengthen intravital microscopy in its historical role as a vital tool in oncology, angiogenesis research, and angiotherapeutic drug development.

Dual mode reflectance and fluorescence confocal laser scanning microscopy for in vivo imaging melanoma progression in murine skin.

A system was designed and developed for simultaneous fluorescence and reflectance contrast in vivo confocal imaging of murine skin using 488 nm (fluorescence mode) and 830 nm (reflectance mode) laser light sources. B16 melanoma cells and B16-enhanced green fluorescent protein (EGFP) cells were inoculated intradermally into transgenic C57BL/6-TgN (ACTbEGFP) 10sb and non-transgenic C57BL/6 mice, respectively. The inoculation sites were imaged sequentially over a 20 d period. The in vivo confocal images were correlated with ex vivo conventional microscopy. The combined modality system provided single-cell resolution and adequate image registration. In fluorescence mode, B16 melanoma cells appeared as dark objects in the bright background of the GFP expressing murine cells of the C57BL/6 transgenic mouse, and the B16-EGFP melanoma cells had a bright signal within a dark background in C57BL/6 mice. In the C57BL/6 transgenic mouse, a population of fluorescent dendritic cells was observed in the vicinity of the tumor cells. The reflectance images provide a useful reference for those areas in the dermal tissues lacking a fluorescent signal. Combined reflectance/fluorescence in vivo confocal laser scanning microscopy holds significant promise for studies of tumor progression in murine skin.

Correcting common errors in identifying cancer-specific serum peptide signatures.

"Molecular signatures" are the qualitative and quantitative patterns of groups of biomolecules (e.g., mRNA, proteins, peptides, or metabolites) in a cell, tissue, biological fluid, or an entire organism. To apply this concept to biomarker discovery, the measurements should ideally be noninvasive and performed in a single read-out. We have therefore developed a peptidomics platform that couples magnetics-based, automated solid-phase extraction of small peptides with a high-resolution MALDI-TOF mass spectrometric readout (Villanueva, J.; Philip, J.; Entenberg, D.; Chaparro, C. A.; Tanwar, M. K.; Holland, E. C.; Tempst, P. Anal. Chem. 2004, 76, 1560-1570). Since hundreds of peptides can be detected in microliter volumes of serum, it allows to search for disease signatures, for instance in the presence of cancer. We have now evaluated, optimized, and standardized a number of clinical and analytical chemistry variables that are major sources of bias; ranging from blood collection and clotting, to serum storage and handling, automated peptide extraction, crystallization, spectral acquisition, and signal processing. In addition, proper alignment of spectra and user-friendly visualization tools are essential for meaningful, certifiable data mining. We introduce a minimal entropy algorithm, "Entropycal", that simplifies alignment and subsequent statistical analysis and increases the percentage of the highly distinguishing spectral information being retained after feature selection of the datasets. Using the improved analytical platform and tools, and a commercial statistics program, we found that sera from thyroid cancer patients can be distinguished from healthy controls based on an array of 98 discriminant peptides. With adequate technological and computational methods in place, and using rigorously standardized conditions, potential sources of patient related bias (e.g., gender, age, genetics, environmental, dietary, and other factors) may now be addressed.