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At least 235 records · Page 13Linked to original sources
PubMed2005

Single-molecule fluorescence imaging of the remote TiO2 photocatalytic oxidation.

The remote TiO2 photocatalytic oxidation reaction of single dyes has been investigated by the single-molecule fluorescent imaging technique. The present results suggest that the active oxygen species (Ox) is most probably the .OH radical, which is generated from the photodecomposition of H2O2 by UV light. The analyses of the number, intensity, and spectrum of individual fluorescence spots at the single-molecule level also indicate that unoxidized and oxidized dyes exist during the bleaching processes of single dyes.

Journal Article↗
PubMed2003

A multispectral fluorescence imaging system: design and initial clinical tests in intra-operative Photofrin-photodynamic therapy of brain tumors.

BACKGROUND AND OBJECTIVES: Intra-operative identification of tumor by fluorescence may improve surgical resection or photodynamic therapy (PDT). A novel instrument was designed, constructed, and tested for this purpose. STUDY DESIGN/MATERIALS AND METHODS: The instrument was designed to provide high-resolution, multi-spectral (five band) fluorescence imaging, and non-contact point spectroscopy, with long working distance ( approximately 50 cm), large field-of-view ( approximately 3 cm diameter), large depth of view ( approximately 2 cm), and 'point-and-shoot' operation. Its performance was determined in tissue-simulating phantoms and in pilot studies in brain tumor resection patients, with or without intra-operative Photofrin-PDT. RESULTS: In phantoms the imaging resolution was approximately 150 microm, while Photofrin concentrations as low as 0.05 or 0.1 microg/g could be detected at the tissue surface or at 0.5 mm depth, respectively. Red Photofrin fluorescence could be clearly visualized post radical resection in all PDT patients, with biopsy confirmation of residual tumor tissue in regions that were not seen as tumor under white light. Photobleaching of Photofrin during PDT was also demonstrated. CONCLUSIONS: The system performed to specification under realistic operating conditions and could reveal unresected residual tumor tissue. It may be used for either PDT dosimetry/monitoring and/or for surgical guidance.

Adult↗
PubMed1995

Mitochondrial Ca2+ overload in primary cultures of rat renal cortical epithelial cells by cytotoxic concentrations of cyclosporine: a digitized fluorescence imaging study.

Cyclosporine (CsA) has been reported to disrupt Ca2+ efflux from mitochondria, which suggests that CsA interference with Ca2+ homeostasis may be related to its nephrotoxicity. Therefore, the purpose of this study was (1) to determine intracellular free Ca2+ concentration ([Ca2+]i) and mitochondrial free Ca2+ concentration ([Ca2+]m) after primary cultures of rat renal cortical epithelial cells were exposed to cytotoxic concentrations of CsA; and (2) to explore the role of disruption of intracellular and mitochondrial Ca2+ homeostasis in CsA-induced cytotoxicity. [Ca2+]i in single kidney cells was examined by digitized fluorescence imaging (DFI) of the Ca2+ fluorescent probe, fura-2, and [Ca2+]m in single cells was observed by DFI of fura-2 entrapped in mitochondria after selective permeabilization of plasma membrane and other non-mitochondrial organelles by digitonin. Mitochondrial membrane potential (delta psi) in single kidney cells was examined by rhodamine 123 (Rh-123) with DFI. Intracellular ATP in kidney cells was determined by a HPLC method. CsA resulted in an elevation in [Ca2+]i and [Ca2+]m, dissipation of delta psi and depletion of ATP in a dose- and time-dependent manner. The elevation of [Ca2+]i and [Ca2+]m and depletion of ATP preceded CsA-induced cytotoxicity in kidney cells as measured by lactate dehydrogenase (LDH) leakage. We conclude that CsA-induced alterations in mitochondrial Ca2+ homeostasis and a subsequent loss of energy supply may play a key role in CsA-induced cytotoxicity in primary cultures of rat renal cortical epithelial cells.

Adenosine Triphosphate↗
PubMed2006

Studies of plasma membrane mechanics and plasma membrane-cytoskeleton interactions using optical tweezers and fluorescence imaging.

We use optical tweezers in conjunction with an optical position-sensing system, which spectrally filters signals generated by a trapped fluorescent microsphere to study plasma membrane (PM) mechanics and its interactions with cytoskeleton. We dynamically measure the PM tethering force on human embryonic kidney cells that are a standard cultured cell line. Recorded tethering force vs. PM displacement profiles, revealed the tether formation process, initiated with linear deformation of the PM, followed by a nonlinear regime and terminated with the local separation of PM. Tethering force vs. displacement profiles were used to estimate tether formation force and stiffness parameter of the PM. Integration of the force-displacement profiles yielded the work of tether formation, including linear and nonlinear components. Our results demonstrate that spectral filtering of the optically trapped fluorescent microsphere image formed on the position-sensing system overcomes the artifacts introduced by the transillumination imaging and allows accurate measures of PM mechanics before and during the initial stages of tether formation.

Biomechanical Phenomena↗
PubMed1997

Experimental and clinical study of detection of glioma at surgery using fluorescent imaging by a surgical microscope after fluorescein administration.

Total resection is the optimal treatment for malignant gliomas. However, an unexpected residual tumor mass is sometimes found on magnetic resonance imaging performed after an operation because of a macroscopically unclear margin of the tumor at surgery. This study was designed to evaluate the effectiveness of fluorescent imaging by a surgical microscope after fluorescein administration for the detection of gliomas at surgery. For this study, we produced two filters for the excitation and emission of fluorescein that can be easily fitted to and removed from a surgical microscope manually during the operation. For the experimental study, Wistar rat brains bearing C6 glioma were removed at appropriate intervals after intravenous administration of 10-20 mg kg-1 body weight of sodium fluorescein, and their surface and coronal section through the tumor were observed using a surgical microscope with the filters. In clinical cases, 1000 mg of sodium fluorescein was intravenously administered to five patients with glioma before tumor resection. In the experimental study, the C6 glioma itself and the edematous brain adjacent to the tumor (within 2-3 mm of the gross surface of the tumor) were well stained a brilliant yellowish green for a few hours. The normal brain was not stained. In clinical cases, the tumors were stained a brilliant yellowish green under fluorescent observation at surgery. The patients had no side effects. At all times the fluorescent observation could be quickly changed to ordinary observation by removing the filters from the surgical microscope. The tumor was also stained a faint yellow under ordinary nonfluorescent observation. Although this contributed to detection of the tumor, the fluorescent staining demarcated the tumor more clearly than nonfluorescent staining. These results suggest that this imaging technique by a surgical microscope with special filters at surgery may be practical and useful for detection of gliomas and warrants further clinical evaluations.

Animals↗
PubMed2003

Near-infrared fluorescence imaging of lymph nodes using a new enzyme sensing activatable macromolecular optical probe.

The aim of this study was to validate the use of near infrared fluorescence imaging (NIRF) using enzyme-sensitive optical probes for lymph node detection. An optical contrast probe that is activated by cystein proteases, such as cathepsin B, was used to visualize lymph nodes by NIRF reflectance imaging. In order to quantitate the uptake of the optical probe in lymphatic tissue, the biodistribution was assessed using the Indium-111 labeled optical probe. Sixteen Balb-c mice were injected either intravenously (i.v.) or subcutaneously (s.c.) with the NIRF-probe (2 micromol cyanine (Cy)/animal; i.v., n=10; s.c., n=6) and imaged 24 h after injection. Signal intensities and target-to-background ratios of various lymph nodes were measured by manual regions of interest (ROIs). Additional signal intensity measurements were performed of excised lymph nodes (n=21) from i.v. injected mice (24 h after injection) and compared with excised lymph nodes (n=8) of non-injected mice. The probe employed in this study was lymphotropic with approximately 3-4% accumulation in lymph nodes (3.4+/-0.8% ID/g). Measurements of the excised lymph nodes (after i.v. injection) confirmed a significant increase in lymph node fluorescence signal from baseline 26+/-7.6 arbitary units (AU) to 146+/-10.9 AU (p<0.0001). A significant increase in lymph node fluorescence signal was also seen in vivo throughout the body after i.v. injection (96+/-7.8 AU) and/or regionally after s.c. injection (141+/-11.5 AU) in comparison with baseline autofluorescence (26+/-7.6 AU). Target-to-background ratio was significantly higher after s.c. injection (6.6%+/-0.81) compared with i.v. injection (4.8+/-0.67%). Detection and visualization of lymph nodes is feasible by NIRF imaging using a cystein-protease sensitive optical probe.

Animals↗
PubMed1990

The importance of calcium regulation in toxic cell injury. Studies utilizing the technology of digital imaging fluorescence microscopy.

The regulation of ions within the cell is of critical importance in both acute and chronic toxicology. Recently, new methods have been developed for measuring such changes in living cells and correlating them with studies of structure, function, and biochemistry. A major revolution has occurred from the linkage between the computer and the light microscope, which has resulted in the use of digital imaging fluorescence microscopy and video intensification microscopy coupled with image analysis. These methods have already yielded much additional information and it is anticipated that their further application by pathologists and toxicologists will continue to uncover the important role of ion deregulation and toxic cell injury.

Animals↗
PubMed2000

Fluorescence imaging of frit effects in capillary separations.

The gradient of five dansylated amino acids in a capillary-based separation system commonly used in capillary liquid chromatography (LC) or capillary electrochromatography (CEC) was followed and examined in detail using a detection method based on laser-induced fluorescence imaging. The detection system consisted of an XeCl excimer laser and an image-intensified charge-coupled device (CCD) camera. Fluorescence intensity profiles along the capillary column were displayed and continuously updated on a computer screen. The detector system enabled the separation dynamics in the column to be monitored. The experiments were focused on the course of events, especially at interfaces. The processes occurring at the beginning of the reversed-phase packing material were studied as well as at the transition from stationary phase to the outlet frit and the open tubular area. Striking differences in signal intensity and separation efficiency were revealed depending on where on the column detection was performed. Furthermore, adsorption of the analytes on the frits was observed.

Amino Acids↗
PubMed2002

Noninvasive fluorescent imaging reliably estimates biomass in vivo.

Whole-body optical imaging of small animals has emerged as a powerful, user friendly, and high-throughput tool for assaying molecular and cellular processes as they occur in vivo. As with any imaging method, the utility of such technology relies on its ability to provide quantitative, biologically meaningful information about the physiologic or pathologic process of interest. Here we used an animal tumor model to evaluate the extent of correlation between noninvasively measured fluorescence and more traditional measurements of biomass (tumor volume and tumor weight). C57/BL6 mice were injected subcutaneously with murine colon adenocarcinoma cells that were engineered to express GFP. Serial measurements of fluorescence intensities were performed with a macroscopic in vivo fluorescence system. The progressive increases in intensity correlated strongly with growth in tumor volume, as determined by caliper measurements (R2 = 0.99). A more stringent correlation was found between fluorescence intensity and tumor weight (R2 = 0.97) than between volume and weight (R2 = 0.89). In a treatment experiment using tumor necrosis factor-alpha, fluorescence intensity (but not tumor volume) was able to differentiate between treated and control groups on day 1 post-treatment. These results validate the ability of noninvasive fluorescent imaging to quantify the number of viable, fluorescent cells in vivo.

Adenocarcinoma↗
PubMed1998

Application of synchrotron radiation X-ray fluorescence imaging combined with histochemical staining to the renal section of mercury-treated rats.

A combination method consisting of synchrotron radiation X-ray fluorescence imaging and histochemical staining was employed to examine the detailed distribution of metal elements and morphological changes in the kidney section of rats exposed simultaneously to mercurial. A single injection of mercuric chloride (5 mg kg (-1)) to rats resulted in significant urinary leakages of the biological markers for acute mercury intoxication. Under this condition (i) a striking damage of brush border, cell loss and a dominant accumulation of mercury in the proximal tubules, (ii) a good correlation between the tubular damage caused by mercury and localization of the toxic metal, and (iii) an obvious distribution difference between zinc and sulfur following mercury exposure, were successfully shown by the present procedure with a 20 micron thick specimen.

Journal Article↗
PubMed1993

A digitized fluorescence imaging study of intracellular free calcium, mitochondrial integrity and cytotoxicity in rat renal cells exposed to ionomycin, a calcium ionophore.

The objective of this study was to explore the role of extracellular Ca2+ and mitochondrial integrity in ionomycin-induced cytotoxicity in primary cultures of rat kidney cortical epithelial cells using digitized fluorescence imaging (DFI), which is a powerful tool for continuously observing the dynamic intracellular biochemistry of single living cells. Using DFI, intracellular free calcium ion concentration ([Ca2+]i), mitochondrial membrane potential and loss of cell viability in individual rat renal cortical epithelial cells were examined temporally by fura-2, rhodamine 123 (Rh-123) and propidium iodide (PI), respectively. Images were taken within 10 min after exposure to 5 and 10 microM ionomycin. These three parameters, [Ca2+]i, mitochondrial membrane potential and cell viability, were also measured in populations of cells by a multiwell fluorescence scanner with fluo-3, Rh-123 and PI, respectively. Cytotoxicity was also assessed by two colorimetric cytotoxicity tests (LDH leakage and mitochondrial MTT reduction). Using DFI, the fluorescence scanner and the colorimetric cytotoxicity tests, we found that exposure of primary cultures of rat kidney cortical epithelial cells to high concentrations of ionomycin (5 and 10 microM) caused a rapid and sustained rise in [Ca2+]i, which preceded dissipation of the mitochondrial membrane potential and loss of cell viability and that chelation of extracellular Ca2+ with EGTA attenuated these responses. We demonstrated the value of using DFI to continuously observe the dynamic intracellular biochemistry of single living cells by establishing a sequence of elevated [Ca2+]i, dissipation of mitochondrial membrane potential and cytotoxicity. We conclude that a combination of the influx of extracellular Ca2+ and loss of mitochondrial integrity may be responsible for the cytotoxicity observed in individual renal cells and populations of renal cells after treatment with ionomycin.

Aniline Compounds↗
PubMed2001

The clinical value of lung imaging fluorescence endoscopy for detecting synchronous lung cancer.

Some patients with non-small cell lung cancer (NSCLC) will also have a synchronous malignant lesion. The lung imaging fluorescence endoscopy (LIFE) has proven better than conventional white light bronchoscopy (WLB) for visualizing premalignant lesions or early stages of lung cancer. In this study, the additional value of LIFE in diagnosing synchronous lung cancers as well as the impact of these findings on definite therapy was analyzed. Seventy-two patients with recently diagnosed NSCLC or pulmonary lesions highly suspect of lung cancer were studied. Patients underwent WLB, followed by LIFE. Apart from the primary lesions, additional abnormal and suspicious lesions seen at WLB and LIFE were scored separately and biopsied. Sixty-nine patients had NSCLC and three patients had small cell lung carcinoma. Apart from the primary lesion, one up to six additional endobronchial lesions were visualized in 48 patients by WLB and/or LIFE. High-grade dysplastic lesions were detected in ten patients, three of whom were eligible for surgery of the primary tumor after completion of the investigations. Three other patients (4.3%) had synchronous cancers (NSCLC). In one patient, the lesion was visualized by LIFE and by WLB. The other two malignant lesions were detected only by LIFE. In these three latter patients, diagnostic work-up and definite treatment was changed, as a result of detection of synchronous lesions. In conclusion, LIFE has additional value in detecting synchronous malignant lesions in patients with primary lung cancer. The detection of these lesions changed diagnostic work-up and definite treatment plan. Therefore, LIFE should be used in the work-up of patients with primary lung cancer.

Adult↗
PubMed2002

Simultaneous collection of topographic and fluorescent images of barley chromosomes by scanning near-field optical/atomic force microscopy.

The present study investigated the applicability of scanning near-field optical/atomic force microscopy (SNOM/AFM) to observations of YOYO-1 stained barley chromosomes. Using this technique, topographic and fluorescent images in the same portion were obtained simultaneously, thus enabling the precise analysis of fluorescent structures in relation to the morphology of chromosomes. In YOYO-1 stained chromosomes, the fluorescent intensity roughly reflected the local amount and/or density of DNA in chromosomes. R-banding of chromosomes stained with YOYO-1 and methyl green was also observed clearly as bright spots of various sizes by this microscope. Thus, the SNOM/AFM is expected to become a useful tool for analysing the structure and function of chromosomes more precisely than before.

Benzoxazoles↗
PubMed2005

Distribution of UV-shielding of the epidermis of sun and shade leaves of the beech (Fagus sylvatica L.) as monitored by multi-colour fluorescence imaging.

Plants can protect against damaging ultraviolet (UV) radiation by accumulating UV-absorbing substances in the epidermis of the leaves. Sun and shade leaves of a free standing beech tree (Fagus sylvatica L.) were studied for the differences in UV-shielding of the epidermis by means of multi-colour fluorescence images taken with UV and blue excitation. The distribution of the fluorescence intensity was detected over intact leaves in the emission maxima in the blue at 440 nm (F440), in the green at 520 nm (F520), in the red at 690 nm (F690) and in the far red at 740 nm (F740). Images of the logarithmic ratio between F690 excited in the blue and the UV (log ((B)F690/(UV)F690)) were calculated representing the relative absorption of UV in the epidermis and thus the degree of UV-shielding. It was found that UV-shielding is stronger for sun leaves than for shade leaves and better for the upper (adaxial) leaf side than for the lower (abaxial) leaf side of both leaf types. Within one leaf the highest value for the ratio log ((B)F690/(UV)F690) and thus the highest UV-shielding was found at the leaf rim which in broad leaves contains young tissue.

Fagus↗
PubMed2003

Dual-color fluorescence imaging distinguishes tumor cells from induced host angiogenic vessels and stromal cells.

We have developed a simple yet powerful technique for delineating the morphological events of tumor-induced angiogenesis and other tumor-induced host processes with dual-color fluorescence. The method clearly images implanted tumors and adjacent stroma, distinguishing unambiguously the host and tumor-specific components of the malignancy. The dual-color fluorescence imaging is effected by using red fluorescent protein (RFP)-expressing tumors growing in GFP-expressing transgenic mice. This model shows with great clarity the details of the tumor-stroma interaction, especially tumor-induced angiogenesis and tumor-infiltrating lymphocytes. The GFP-expressing tumor vasculature, both nascent and mature, could be readily distinguished interacting with the RFP-expressing tumor cells. GFP-expressing dendritic cells were observed contacting RFP-expressing tumor cells with their dendrites. GFP-expressing macrophages were observed engulfing RFP-expressing cancer cells. GFP lymphocytes were seen surrounding cells of the RFP tumor, which eventually regressed. Dual-color fluorescence imaging visualizes the tumor-host interaction by whole-body imaging and at the cellular level in fresh tissues, dramatically expanding previous studies in fixed and stained preparations.

Animals↗