The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Edward G Stopa - One of the best experts on this subject based on the ideXlab platform.
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labeling of human retinohypothalamic tract with the Carbocyanine dye dii
Brain Research, 1991Co-Authors: Deborah I Friedman, Kelly J Johnson, Regina L Chorsky, Edward G StopaAbstract:Abstract The Carbocyanine dye, DiI, was used to demonstrate human retinohypothalamic tract (RHT) projections in 6 normal human postmortem brains. In 5 of 6 brains, labeling was seen extending from the site of implantation in the distal optic nerve to both the ipsilateral and contralateral suprachiasmatic nuclei. This study confirms the presence of RHT projections in humans, and demonstrates the usefulness of DiI for neuronal tracing in human postmortem tissue.
Harvey J. Karten - One of the best experts on this subject based on the ideXlab platform.
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Tracing developing pathways in the brain: A comparison of Carbocyanine dyes and cholera toxin B subunit
Neuroscience, 2003Co-Authors: R.m. Russell, R.t Nguyen, Harvey J. KartenAbstract:Abstract The present study examined the efficiency of fluorescent Carbocyanine dye 1,1′-dioctadecyl-3,3,3′,3′-tetramethylinodoCarbocyanine perchlorate and cholera toxin B subunit in tracing the crossed tectal projection to the nucleus rotundus of the thalamus (tectorotundal pathways) of paraformaldehyde-fixed and living chick embryos. The tracers were injected into the optic tectum under three experimental conditions (Carbocyanine postfix, Carbocyanine in vivo , and cholera toxin B subunit in vivo ) and the anterograde transport of the nucleus rotundus was monitored and compared. In the Carbocyanine postfix method, small crystals of Carbocyanine dye were inserted into the tectum of paraformaldehyde-fixed embryos. A 6-month post-insertion period was required to label the crossed tectorotundal pathway. Results showed that tectal neurons did not begin to innervate the ipsilateral nucleus rotundus until embryonic day 9 and the contralateral nucleus rotundus until embryonic day 17. This slow progression of labeling through the crossed tectal projection resulted in significant contrast of the labeling between the ipsilateral and contralateral nuclei rotundus. In the Carbocyanine in vivo method, a small volume of Carbocyanine dye solution was injected into the tectum of living embryos. A 8- to 12-h survival period was sufficient enough to label the tectorotundal pathway. By embryonic day 8, the labeled axons terminated in the ipsilateral nucleus rotundus and the crossed tectorotundal projection was first detected by embryonic day 10. Similarly, in the cholera toxin B subunit in vivo method, a small volume of cholera toxin B subunit solution was injected into the tectum of living embryos. After a 6- to 10-h survival period, heavily labeled axons were found to innervate bilaterally the nucleus rotundus by embryonic day 8. This appeared to be the earliest schedule for detecting the crossed tectorotundal projection, compared with that of both the postfix and in vivo methods of Carbocyanine dye. Based on the differences in the detectability of the crossed tectorotundal projection between the postfix and in vivo methods, the present data suggest that the former method is of limited purpose for labeling tectal collaterals during embryogenesis. Moreover, given the rapid transport rate and absence of photobleaching, which is often seen when using Carbocyanine dye, the cholera toxin B subunit in vivo method appears to be the tracer of choice for investigating embryonic pathways.
Kathryn B. Grant - One of the best experts on this subject based on the ideXlab platform.
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Oxidative cleavage of DNA by pentamethine Carbocyanine dyes irradiated with long-wavelength visible light.
Bioorganic & medicinal chemistry letters, 2013Co-Authors: Carla T. Mapp, Maged Henary, Eric A. Owens, Kathryn B. GrantAbstract:Abstract Here we report the synthesis of seven symmetrical Carbocyanine dyes in which two nitrogen-substituted benz[ e ]indolium rings are joined by a pentamethine bridge that is meso -substituted with chlorine or bromine versus hydrogen. The heteroatom of benz[ e ]indolium is modified with a phenylpropyl, methyl, or cationic quaternary ammonium group. In reactions containing micro molar concentrations of halogenated dye, irradiation at 575, 588, 623, or 700 nm produces good photocleavage of plasmid DNA. UV–visible spectra show that the Carbocyanines are in their H-aggregated and monomeric forms. Scavenger experiments point to the involvement of singlet oxygen and hydroxyl radicals in DNA photocleavage.
Samuel Achilefu - One of the best experts on this subject based on the ideXlab platform.
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near infrared dichromic fluorescent Carbocyanine molecules
Angewandte Chemie, 2008Co-Authors: Zongren Zhang, Mikhail Y Berezin, Jeff L F Kao, Andre Davignon, Mingfeng Bai, Samuel AchilefuAbstract:Central to major advances in biochemical assays, molecularsensor technologies, and molecular optical imaging arefluorescent materials that provide high detection sensitivityformolecularprocesses.Inbiologicalopticalimaging,thelowtissueautofluorescenceandthedeeppenetrationoflightintothetissuesobservedatwavelengthsbetween650 and900nmallow the use of near-infrared (NIR) fluorescent dyes ascontrast agents in heterogeneous systems.
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Synthesis, metal coordination, and cellular internalization of a siderophore-bearing NIR fluorescent Carbocyanine probe
Optical Molecular Probes for Biomedical Applications, 2006Co-Authors: Sharon Bloch, Samuel AchilefuAbstract:In order to explore novel NIR fluorescent probes for optical imaging in biomedicines, one desferrioxamine (DFO)-bearing NIR fluorescent probe was designed and synthesized based on a dicarboxylic acid-containing Carbocyanine (Cypate). Similar to the free DFO, the resulting conjugate Cypate-DFO showed high binding affinity with Fe(III) and Ga(III) as identified by ES-MS. Nevertheless, the iron binding was found to quench its fluorescent emission significantly, suggesting that the siderophore moiety might perturb the spectroscopic properties of the attached Carbocyanine fluorophore through metal binding. As observed by fluorescence microscopy, Cypate-DFO showed significant cellular internalization in A549 cells in vitro. Further studies on novel Cypate-DFO derivatives of this type may reveal some exciting properties and biological activities.
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Multivalent Carbocyanine molecular probes: synthesis and applications.
Bioconjugate chemistry, 2005Co-Authors: Sharon Bloch, Jeffery Kao, Samuel AchilefuAbstract:Synergistic multivalent interactions can amplify desired chemical or biological molecular recognitions. We report a new class of multicarboxylate-containing Carbocyanine dye constructs for use as o...
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Polyvalent Carbocyanine Molecular Beacons for Molecular Recognitions
Journal of the American Chemical Society, 2004Co-Authors: Sharon Bloch, Samuel AchilefuAbstract:Polyvalent carboxylate-terminating near-infrared (NIR) Carbocyanine molecular beacons were prepared by homologation of reactive carboxyl groups of the beacon with imino diacetic acid. Their conjugation with unprotected d-(+)-glucosamine gave dendritic arrays of the carbohydrate on an inner NIR chromophore core. In vivo evaluation of the dendritic glucosamine constructs shows enhanced uptake in proliferating tumor cells relative to surrounding normal tissue. The structural framework of these polyvalent beacons permits the amplification by synergistic effects of a variety of bioactive motifs or chemical sensors in molecular recognition interactions without dramatic change of their desirable NIR spectral properties.
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Synthesis, in vitro receptor binding, and in vivo evaluation of fluorescein and Carbocyanine peptide-based optical contrast agents.
Journal of medicinal chemistry, 2002Co-Authors: Samuel Achilefu, Hermo N. Jimenez, Richard B. Dorshow, Joseph E. Bugaj, Elizabeth G. Webb, R. Randy Wilhelm, Raghavan Rajagopalan, Jill Johler, Jack L. ErionAbstract:Site-specific delivery of drugs and contrast agents to tumors protects normal tissues from the cytotoxic effects of drugs and enhances the contrast between normal and pathologic tissues. One approach to achieve selectivity is to target overexpressed receptors on the membranes of tumor cells and to visualize the tumors by a noninvasive optical imaging method. Accordingly, we conjugated fluorescein and Carbocyanine dyes to somatostatin and bombesin receptor-avid peptides and examined their receptor binding affinities. We also prepared potential dual imaging probes consisting of a bioactive peptide for tumor targeting, a biocompatible dye for optical imaging, and a radioactive or paramagnetic metal chelator for scintigraphic or magnetic resonance imaging of tumors. Using these approaches, the resulting Carbocyanine derivatives of somatostatin and bombesin analogues retained high binding for their respective receptors. Further evaluation of representative molecules in rats bearing somatostatin- and bombesin-positive tumors showed selective uptake of the agents by the tumor cells. Unlike Carbocyanine derivatives, the receptor binding of fluorescein-somatostatin peptide conjugates was highly sensitive to the type of linker and the site of fluorescein attachment on the nonreceptor binding region of the peptide. In general, the presence of flexible linkers disrupted binding affinity, possibly due to the interaction of the linker's thiourea group with the peptide's cyclic disulfide bond. While the receptor binding affinity of the dual probes was not dependent on the type of chelating group examined, it was affected by the relative positions of fluorescein and chelator on the lysine linker. For somatostatin compounds, best results were obtained when the chelator was on the alpha-amino lysine linker and fluorescein was on the epsilon-amino group. In contrast, conjugation of the chelator to epsilon- and fluorescein to the alpha-amino lysine linker of bombesin peptides resulted in high receptor binding. These findings indicate that despite their small size, conjugation of dyes to truncated somatostatin and bombesin peptide analogues results in promising diagnostic agents that retain high receptor binding activity in vitro. The results further show that these contrast agents can selectively and specifically localize in receptor-positive tumors in rat models.
Tomoyuki Kinoshita - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and analysis of UV/visible spectra of Carbocyanine dimer models
Dyes and Pigments, 2008Co-Authors: Masaru Kimura, Takeshi Fukai, Tomoyuki KinoshitaAbstract:Abstract Dimers 1 and 2 , having a pair of the Carbocyanine moieties connected at the meso -positions by an –O–Ph–O– or –S–Ph–S– bridge, were prepared. Their UV/visible spectra displayed a first absorption maxima at ca. 750 nm, a second absorption maxima at ca. 800 nm and a shoulder at ca. 850 nm. Since MOPAC calculations indicated that the configuration of the dimers was folded, but twisted, strong H-type coupling together with weaker J-type coupling takes place along the longer axis of the dimers. The UV/visible spectra of the dimers were characterized by a split in the long wavelength absorption of the corresponding Carbocyanine chromophore into a more intense blue shift and a less intense red shift. Remarkably, the dimers showed greater sensitivity to solvent polarity than the monomers 3 and 4 .