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PubMedDate not supplied

Synthesis and application of a water-soluble near-infrared dye for cancer detection using optical imaging.

A novel water-soluble 2-[2-(2-chloro-3-{2-[3,3-dimethyl-5-sulfo-1-(4-sulfo-butyl)-3H-indol-2-yl]-vinyl}-cyclohex-2-enylidene)-ethylidene]-3,3-dimethyl-1-(4-sulfo-butyl)-2,3-dihydro-1H-indole-5-carboxylic acid (dye 2) was developed via an asymmetric approach. With an additional sulfonate group, the near-infrared feature of this dye exhibited a 2-fold increase in quantum yield compared to the previous generation. The current synthetic strategy provided a single carboxylic group as a handle for conjugation, thus allowing selectivity for bioconjugation. The stability of this dye was demonstrated by labeling peptides via solid-phase peptide chemistry. The in vivo optical imaging showed potential and broad applications of this dye in developing molecular-based beacons for cancer detection.

Animals↗
PubMed2005

In vitro anticancer activities and optical imaging of novel intercalative non-cisplatin conjugates.

The first pi-conjugated macrocyclic diimine and triaza DNA-binding intercalators and their platinum(II) conjugates have been synthesized by direct Schiff base cyclocondensation. The in vitro anticancer activities of compounds 3, 4, and 5 were tested on five cancer cell lines: MCF-7, A549, P388, A2780, and A2780cisR. Ovarian tumors were included specifically to evaluate the new conjugates' ability to circumvent A2780cisR resistance. Antitumor effects of the newly conjugated compounds were compared to those of cisplatin. The data clearly indicate that improved drug efficiencies are achieved as a result of the intercalative moieties. The luminescent probe that was integrated in complexes 8-10 made it possible to monitor drug penetration using optical imaging. Enhanced targeting of tumor nuclei by the study compounds was confirmed by confocal microscopy. This paper describes a new class of platinum-based antitumorals differing from cisplatin in several critical aspects with the potential for significantly improving clinical outcomes in cancer patients.

Antineoplastic Agents↗
PubMed1998

Time-resolved and nonlinear optical imaging for medical applications.

In this article, we have presented an overview of emerging novel techniques for early-light transillumination imaging as well as nonlinear optical tomography of body organs. The use of light for probing and imaging biomedical media offers the promise for development of safe, noninvasive, and inexpensive clinical imaging modalities with diagnostic ability. The strong scattering of light by biological tissues buries the shadowgram formed by forward-propatating image-bearing photons in the background noise of multiple-scattered light. Several methods for extraction of image-bearing light that capitalize on spatial, temporal and polarization characteristics of transmitted light are reviewed. More recently emerging nonlinear-optical histopathology methods for imaging subsurface structures of tissues in terms of its local spatial symmetry and molecular content are introduced. The progress made so far indicates that some of these techniques are apt to make a transition from laboratory to useful clinical modalities.

Animals↗
PubMedDate not supplied

Optical imaging of orientation and ocular dominance maps in area 17 of cats with convergent strabismus.

Strabismus (or squint) is both a well-established model for developmental plasticity of the brain and a frequent clinical symptom. While the layout and topographic relationship of functional domains in area 17 of divergently squinting cats has been analyzed extensively in recent years (e.g. Löwel et al., 1998), functional maps in convergently squinting animals have so far not been visualized with comparable detail. We have therefore investigated the functional organization of area 17 in adult cats with a surgically induced convergent squint angle. In these animals, visual acuity was determined by both behavioral tests and recordings of visual evoked potentials, and animals with comparable acuities in both eyes were selected for further experiments. The functional layout of area 17 was visualized using optical imaging of intrinsic signals. Monocular iso-orientation domains had a patchy appearance and their layout was different for left and right eye stimulation, so that segregated ocular dominance domains could be visualized. Iso-orientation domains exhibited a pinwheel-like organization, as previously described for normal and divergently squinting cats. Mean pinwheel density was the same in the experimental and control animals (3.4 pinwheel centers per mm2 cortical surface), but significantly (P < 0.00001) higher than that reported previously for normal and divergently squinting cats (2.7/mm2). A comparison of orientation with ocular dominance maps revealed that iso-orientation domains were continuous across the borders of ocular dominance domains and tended to intersect these borders at steep angles. However, in contrast to previous reports in normally raised cats, orientation pinwheel centers showed no consistent topographical relationship to the peaks of ocular dominance domains. Taken together, these observations indicate an overall similarity between the functional layout of orientation and ocular dominance maps in area 17 of convergently and divergently squinting cats. The higher pinwheel densities compared with previous reports suggest that animals from different gene pools might generally differ in this parameter and therefore also in the space constants of their cortical orientation maps.

Animals↗
PubMedDate not supplied

Single-cell optical imaging of the phagocyte NADPH oxidase.

The phagocyte NADPH oxidase is a key component of the innate immune response against invading microorganisms, because the generation of superoxide (O(2)(-)) inside the phagocytic vacuole by this enzyme is responsible for microbial killing by mechanisms that are directly or indirectly dependent on reactive oxygen species (ROS) formation. Most of what is known about the membrane-embedded and cytosolic NADPH oxidase subunits and their intricate network of interactions on assembly and activation has been derived from biochemical and biophysical studies involving subcellular fractionation or reconstituted cell-free systems. Such investigations can be complemented by single-cell microscopy on phagocytes, which may reveal spatial and/or temporal details about NADPH oxidase assembly that cannot be obtained from fractionated-cell assays. In recent years, we have investigated the NADPH oxidase in neutrophils using two complementary optical imaging techniques: Raman microscopy, a vibrational spectroscopic technique that does not require protein labeling, and live-cell fluorescence microscopy, which sheds light on the dynamics of NADPH oxidase assembly in individual cells. Here, we briefly introduce these techniques, compare their characteristics, and show their potential for studying NADPH oxidase at the single-cell level. New microscopy data are presented to illustrate the versatility of Raman and fluorescence microscopy on intact neutrophils.

Adult↗
PubMed2001

Improved data processing for optical imaging of developing neuronal connectivity in the neonatal mouse barrel cortex.

Optical recording methods using voltage-sensitive dyes have proven valuable for the analysis of neuronal networks both in vivo and in vitro. This technique detects membrane potential changes as changes in the absorption or fluorescence of voltage-sensitive dyes incorporated into the cellular plasma membranes. The reliability of the optical recording technique is dependent on the dye-related response being fast enough to follow the electrical activity and of the response being more or less proportional to the amplitude of the membrane potential change. A high spatial resolution can be achieved using an appropriate imaging system and a dye with a response of sufficiently high signal-to-noise ratio. Thus, it is now anticipated that this method will be able to shed more light on the spatio-temporal information processing of neocortical circuitry. While the FUJIX HR Deltaron 1700 optical imaging system offers a reasonably high time (0.6 ms) and space-resolution (7 microm at 10x magnification), one drawback of this system, however, is its relatively poor data processing capabilities. We have therefore developed a protocol to improve the signal-to-noise ratio by modifying the calculation algorithm of the optical data. Consequently, we characterized optical responses in thalamocortical slices to find developmental landmarks of thalamocortical and intracortical connectivity in the neonatal mouse barrel cortex. Successful application of this method has been published on the analysis of thalamocortical glutamatergic connectivity [8].

Algorithms↗
PubMed2001

The correlation between polarization modulated near-field optical images and the anisotropy of the probe.

The true anisotropic images taken with the polarization modulation near-field optical microscope are often influenced by the linear dichroism of the tapered fibre probe. In this paper, we develop a new method to separate the anisotropic image form probe's dichroism. Our calculations show that the near-field optical image is simply a vector sum of the sample's dichroism and the probe's dichroism, when the probe's anisotropy is small. With this result, we demonstrate the true anisotropic images of poly(phenylene vinylene) (PPV) thin films. The PPV films show non-uniform mesoscale dichroic domains with average domain size, approximately 0.3 mm, and the coefficient for linear dichroism is 1.25 x 10(4) cm(-1).

Journal Article↗
PubMed2006

Effects of interactions among wave aberrations on optical image quality.

Wave aberrations degrade the optical quality of the eye relative to the diffraction limit, but there are situations in which having slightly aberrated optics can provide some relative visual benefits. This fact led us to consider whether interactions among aberrations in the eye's wavefront produce an advantage for image quality relative to wavefronts with randomized combinations of aberrations with the same total RMS error. Total ocular wave aberrations from two experimental groups and corneal wave aberrations from one group were measured and expressed as Zernike polynomial expansions through the seventh-order. In a series of Monte Carlo simulations, modulation transfer functions (MTFs) for the measured wave aberrations were compared to distributions of artificial MTFs for wavefronts created by randomizing the sign or orientation of the aberrations, while maintaining the RMS error within each Zernike order. In a control condition, "synthetic" model eyes were produced by choosing each individual aberration term at random from individuals in the experimental group, and again MTFs were compared for original and randomized signs. Results were summarized by the MTF ratio: real MTF/mean simulated MTF, as a function of spatial frequency. For a 6mm pupil, the mean MTF ratio for total ocular aberrations was greater than 1.0 up to 60 cycles per degree, suggesting that the eye's aberrations are not independent and that there may be a positive functional consequences to their interrelations. This positive relation did not hold for corneal aberrations alone, or for the synthetic eyes.

Adult↗
PubMed2006

Differentiating hemodynamic responses in rat primary somatosensory cortex during non-noxious and noxious electrical stimulation by optical imaging.

Nociception in the primary somatosensory (S1) cortex remains in need of further elucidation. The spatiotemporal comparison on changes of the cerebral blood volume evoked by graded peripheral electrical stimulation was performed in rat contralateral somatosensory cortex with optical intrinsic signal imaging (OISI, optical reflectance at 550 nm). Non-noxious electrical stimulus was applied with 5 Hz pulses (0.5 ms peak duration) for 2 s at the threshold current for muscle twitch, while noxious stimulus was delivered at currents of 10x and 20x amplitude of the predetermined threshold. Although the dimensions of peak response defined in the spatial domain (cerebral blood volume increase) in the S1 cortex presented no significant difference under non-/noxious stimuli, its early response component (about 1 s after stimulation onset) revealed by OISI technique was suggested to differentiate the loci of activated cortical region due to different stimulation in this study. The magnitude and duration of the optical intrinsic signal (OIS) response was found increasing with the varying stimulus intensity. Regions activated by the delivery of a noxious stimulus were surrounded by a ring of inverted optical intrinsic signal, the amplitude of that was inversely proportional to the strength of the optical signal attributable to activation. Intense stimuli significantly augmented the inverted optical signal in magnitude and spatial extent. These results indicated that noxious stimulation evoked different response patterns in the contralateral S1 cortex. The magnitude-dependent inverted optical signal might contribute to the differentiation of nociceptive input in the S1 cortex.

Afferent Pathways↗
PubMed2005

Optical imaging of cervical pre-cancers with structured illumination: an integrated approach.

OBJECTIVE: Structured illumination microscopy is an inexpensive alternative to confocal microscopy that allows optical sectioning at a sub-cellular resolution. However, its application in imaging biological tissue has been limited by inadequate contrast present in them especially in reflectance imaging. Novel, optically active contrast agents like gold nanoparticles and quantum dots targeted against biomarkers of cancer can be integrated with structured illumination to image both the morphological and biochemical changes associated with epithelial pre-cancers. METHODS: We modified the optical path of a widefield microscope to implement structured illumination both in reflectance and fluorescence modes. For imaging, we used 25-nm-diameter gold nanoparticles and CdSe quantum dots for reflectance and fluorescence imaging, respectively, to label three-dimensional tissue constructs of SiHa cervical cancer cells. Contrast agents were targeted against the epidermal growth factor receptor (EGFR) using an anti-EGFR monoclonal antibody. Agents targeted with a non-specific IgG antibody served as a control to monitor non-specific labeling. RESULTS: Our result shows that optically sectioned images taken with structured illumination are very comparable to those obtained using confocal microscopy. Moreover, images of three-dimensional cultures stained with the anti-EGFR agents show significantly more image intensity than those stained with the IgG targeted control. CONCLUSION: Our findings suggest that the combination of novel optical contrast agents and structured illumination can differentiate neoplastic cells which overexpress EGFR from normal cells in intact tissue. Combining structured illumination microscopy with novel contrast agents can potentially provide a powerful and inexpensive tool to aid in the detection of cervical pre-cancers.

Antibodies, Monoclonal↗
PubMedDate not supplied

Polarization properties of bent-type optical fibre probe for magneto-optical imaging.

Quantitative evaluation of magneto-optical parameters is necessary in order to apply scanning near-field optical microscope (SNOM) technology to the study of magnetism on the mesoscopic scale. For this purpose, quantitative knowledge of polarization transmission properties through an optical fibre probe is required. We therefore determined the Stokes parameters of the bent-type optical fibre probe that is used as a cantilever for atomic force microscope operation in our SNOM system. As a result, it is found that the degree of polarization is maintained in the light emitted from the probe, although the probe acts as if it were a wave plate. This anisotropic polarization state of the light emitted from the probe was compensated for by using a Berek compensator placed in front of the fibre coupler.

Journal Article↗
PubMed2000

Physician experience with an optical image guidance system for sinus surgery.

OBJECTIVES/HYPOTHESIS: Intraoperative guidance systems have been developed which use infrared tracking technology to assist with anatomical localization during sinus surgery. Although the introduction of this technology is intended to increase the safety and efficacy of sinus surgery, little is known about its actual impact in the clinical setting. The objective of this report was to study the application and utilization of an image guidance system shared by multiple sinus surgeons in a specialty hospital. STUDY DESIGN: Combined prospective case study and retrospective analysis of physician surveys. METHODS: An optical-based image guidance system (LandmarX, Xomed, Inc., Jacksonville, FL) was used by 34 physicians to perform 754 sinonasal surgeries over a 2.5-year period at Massachusetts Eye and Ear Infirmary. In 19 cases, system registration was repeated during surgery to measure the effect of fiducial placement on system accuracy. RESULTS: The measured accuracy of anatomical localization at the start of surgery (mean value, 1.69 +/- 0.38 mm) was comparable to the perceived accuracy of 1 to 3 mm that was reported by 79% of surgeons surveyed. Operating room time (mean period, 130.6 +/- 41.1 min) correlated with the surgical procedure performed (P < .05), but not with the disease stage or revision rate. According to a majority of surgeons, use of the image guidance equipment increased operating room time by 15 to 30 minutes during initial cases and by 5 to 15 minutes once experience with the equipment had been acquired. More than 90% of surgeons anticipated their continued use of the image guidance equipment for sinus surgery at a similar or greater level in the future. CONCLUSION: An optical-based image guidance system can be successfully integrated into a multisurgeon operating room environment. Use of the system provides accurate anatomical localization during sinus surgery and results in a relatively high level of physician satisfaction.

Adolescent↗
PubMedDate not supplied

Optical imaging of tumor hypoxia and evaluation of efficacy of a hypoxia-targeting drug in living animals.

Solid tumors containing more hypoxic regions show a more malignant phenotype by increasing the expression of genes encoding angiogenic and metastatic factors. Hypoxia-inducible factor-1 (HIF-1) is a master transcriptional activator of such genes, and thus, imaging and targeting hypoxic tumor cells where HIF-1 is active are important in cancer therapy. In the present study, HIF-1 activity was monitored via an optical in vivo imaging system by using a luciferase reporter gene under the regulation of an artificial HIF-1-dependent promoter, 5HRE. To monitor tumor hypoxia, we isolated a stable reporter-transfectant, HeLa/5HRE-Luc, which expressed more than 100-fold luciferase in response to hypoxic stress, and observed bioluminescence from its xenografts. Immunohistochemical analysis of the xenografts with a hypoxia marker, pimonidazole, confirmed that the luciferase-expressing cells were hypoxic. Evaluation of the efficacy of a hypoxia-targeting prodrug, TOP3, using this optical imaging system revealed that hypoxic cells were significantly diminished by TOP3 treatment. Immunohistochemical analysis of the TOP3-treated xenografts confirmed that hypoxic cells underwent apoptosis and were removed after TOP3 treatment. These results demonstrate that this model system using the 5HRE-luciferase reporter construct provides qualitative information (hypoxic status) of solid tumors and enables one to conveniently evaluate the efficacy of cancer therapy on hypoxia in malignant solid tumors.

Animals↗
PubMed2007

Molecular optical imaging of therapeutic targets of cancer.

Recent progress in discerning the molecular events that accompany carcinogenesis has led to development of new cancer therapies directly targeted against the molecular changes of neoplasia. Molecular-targeted therapeutics have shown significant improvements in response rates and decreased toxicity as compared to conventional cytotoxic therapies which lack specificity for tumor cells. In order to fully explore the potential of molecular-targeted therapy, a new set of tools is required to dynamically and quantitatively image and monitor the heterogeneous molecular profiles of tumors in vivo. Currently, molecular markers can only be visualized in vitro using complex immunohistochemical staining protocols. In this chapter, we discuss emerging optical tools to image in vivo a molecular profile of risk-based hallmarks of cancer for selecting and monitoring therapy. We present the combination of optically active, targeted nanoparticles for molecular imaging with advances in minimally invasive optical imaging systems, which can be used to dynamically image both a molecular and phenotypic profile of risk and to monitor changes in this profile during therapy.

Animals↗
PubMed1998

Stationary headband for clinical time-of-flight optical imaging at the bedside.

Conventional brain-imaging modalities may be limited by high cost, difficulty of bedside use, noncontinuous operation, invasiveness or an inability to obtain measurements of tissue function, such as oxygenation during stroke. Our goal was to develop a bedside clinical device able to generate continuous, noninvasive, tomographic images of the brain using low-power nonionizing optical radiation. We modified an existing stage-based time-of-flight optical tomography system to allow imaging of patients under clinical conditions. First, a stationary head-band consisting of thin, flexible optical fibers was constructed. The headband was then calibrated and tested, including an assessment of fiber lengths, the existing system software was modified to collect headband data and to perform simultaneous collection of data and image reconstruction, and the existing hardware was modified to scan optically using this headband. The headband was tested on resin models and allowed for the generation of tomographic images in vitro; the headband was tested on critically ill infants and allowed for optical tomographic images of the neonatal brain to be obtained in vivo.

Brain↗
PubMed1989

Improved control of image optical density with low-dose digital and conventional radiography in bedside imaging.

The technical and diagnostic performance of simultaneously acquired low-dose (44% of standard dose) storage-phosphor digital radiographs (system resolution = 0.2 mm, 10 bits) were compared with those of standard-dose conventional bedside radiographs of the chest in 32 patients. The mean optical density (OD) of the lungs (800 measurements) was closer to the ideal density with digital radiography (1.45 OD +/- 0.20 [standard deviation] vs 1.75 OD +/- 0.53) and was less often outside the usable range (2.5% vs 42.5%). Receiver operating characteristic analysis for detection of simulated nodules and monitoring devices (nine readers, 4,608 observations) showed that digital radiography was superior to conventional radiography (P less than .05) for four of the nine readers and equivalent to conventional radiography for five readers. The authors concluded that digital radiography produces more consistent and ideal image density and performs at least as well as conventional radiography under phantom test conditions.

Absorptiometry, Photon↗
PubMed2007

[Optical imaging of fluorescence in the near infrared. From passive to enzymatically activated contrast medium].

The molecular imaging of specific targets using optical methods is currently possible in vivo, in part due to the advances in imaging modalities (epifluorescence, fluorescent endoscopy, fluorescence mediated tomography, intravital fluorescence microscopy), and in part due to the development of better contrast media. These are composed of a suitable fluorochrome, usually with emission in the near infrared due to tissue penetration, as well as by molecular specific contrast media from ligands. The latest generation of contrast media is not fluorescent in its unactivated state. Fluorescence first occurs after contact with certain (e.g. disease specific) enzymes by which a minimally unspecific fluorescent background as well as molecular specificity is made possible.

Biomarkers↗
PubMed2005

Gold nanocages: bioconjugation and their potential use as optical imaging contrast agents.

Gold nanocages of <40 nm in dimension have been synthesized using the galvanic replacement reaction between Ag nanocubes and HAuCl4 in an aqueous solution. By controlling the molar ratio between Ag and HAuCl4, the gold nanocages could be tuned to display surface plasmon resonance peaks around 800 nm, a wavelength commonly used in optical coherence tomography (OCT) imaging. OCT measurements on phantom samples indicate that these gold nanocages have a moderate scattering cross-section of approximately 8.10 x 10(-16) m2 but a very large absorption cross-section of approximately 7.26 x 10(-15) m2, suggesting their potential use as a new class of contrast agents for optical imaging. When bioconjugated with antibodies, the gold nanocages have also been demonstrated for specific targeting of breast cancer cells.

Cell Line, Tumor↗